1 /*
   2  * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "code/icBuffer.hpp"
  27 #include "gc_implementation/g1/bufferingOopClosure.hpp"
  28 #include "gc_implementation/g1/concurrentG1Refine.hpp"
  29 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
  30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  31 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
  32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  33 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
  34 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
  35 #include "gc_implementation/g1/g1EvacFailure.hpp"
  36 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
  37 #include "gc_implementation/g1/g1Log.hpp"
  38 #include "gc_implementation/g1/g1MarkSweep.hpp"
  39 #include "gc_implementation/g1/g1OopClosures.inline.hpp"

  40 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  41 #include "gc_implementation/g1/heapRegion.inline.hpp"
  42 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  43 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
  44 #include "gc_implementation/g1/vm_operations_g1.hpp"
  45 #include "gc_implementation/shared/isGCActiveMark.hpp"
  46 #include "memory/gcLocker.inline.hpp"
  47 #include "memory/genOopClosures.inline.hpp"
  48 #include "memory/generationSpec.hpp"
  49 #include "memory/referenceProcessor.hpp"
  50 #include "oops/oop.inline.hpp"
  51 #include "oops/oop.pcgc.inline.hpp"
  52 #include "runtime/aprofiler.hpp"
  53 #include "runtime/vmThread.hpp"
  54 
  55 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  56 
  57 // turn it on so that the contents of the young list (scan-only /
  58 // to-be-collected) are printed at "strategic" points before / during
  59 // / after the collection --- this is useful for debugging
  60 #define YOUNG_LIST_VERBOSE 0
  61 // CURRENT STATUS
  62 // This file is under construction.  Search for "FIXME".
  63 
  64 // INVARIANTS/NOTES
  65 //
  66 // All allocation activity covered by the G1CollectedHeap interface is
  67 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  68 // and allocate_new_tlab, which are the "entry" points to the
  69 // allocation code from the rest of the JVM.  (Note that this does not
  70 // apply to TLAB allocation, which is not part of this interface: it
  71 // is done by clients of this interface.)
  72 
  73 // Notes on implementation of parallelism in different tasks.
  74 //
  75 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
  76 // The number of GC workers is passed to heap_region_par_iterate_chunked().
  77 // It does use run_task() which sets _n_workers in the task.
  78 // G1ParTask executes g1_process_strong_roots() ->
  79 // SharedHeap::process_strong_roots() which calls eventuall to
  80 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
  81 // SequentialSubTasksDone.  SharedHeap::process_strong_roots() also
  82 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
  83 //
  84 
  85 // Local to this file.
  86 
  87 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  88   SuspendibleThreadSet* _sts;
  89   G1RemSet* _g1rs;
  90   ConcurrentG1Refine* _cg1r;
  91   bool _concurrent;
  92 public:
  93   RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
  94                               G1RemSet* g1rs,
  95                               ConcurrentG1Refine* cg1r) :
  96     _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
  97   {}
  98   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
  99     bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
 100     // This path is executed by the concurrent refine or mutator threads,
 101     // concurrently, and so we do not care if card_ptr contains references
 102     // that point into the collection set.
 103     assert(!oops_into_cset, "should be");
 104 
 105     if (_concurrent && _sts->should_yield()) {
 106       // Caller will actually yield.
 107       return false;
 108     }
 109     // Otherwise, we finished successfully; return true.
 110     return true;
 111   }
 112   void set_concurrent(bool b) { _concurrent = b; }
 113 };
 114 
 115 
 116 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
 117   int _calls;
 118   G1CollectedHeap* _g1h;
 119   CardTableModRefBS* _ctbs;
 120   int _histo[256];
 121 public:
 122   ClearLoggedCardTableEntryClosure() :
 123     _calls(0)
 124   {
 125     _g1h = G1CollectedHeap::heap();
 126     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
 127     for (int i = 0; i < 256; i++) _histo[i] = 0;
 128   }
 129   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 130     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 131       _calls++;
 132       unsigned char* ujb = (unsigned char*)card_ptr;
 133       int ind = (int)(*ujb);
 134       _histo[ind]++;
 135       *card_ptr = -1;
 136     }
 137     return true;
 138   }
 139   int calls() { return _calls; }
 140   void print_histo() {
 141     gclog_or_tty->print_cr("Card table value histogram:");
 142     for (int i = 0; i < 256; i++) {
 143       if (_histo[i] != 0) {
 144         gclog_or_tty->print_cr("  %d: %d", i, _histo[i]);
 145       }
 146     }
 147   }
 148 };
 149 
 150 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
 151   int _calls;
 152   G1CollectedHeap* _g1h;
 153   CardTableModRefBS* _ctbs;
 154 public:
 155   RedirtyLoggedCardTableEntryClosure() :
 156     _calls(0)
 157   {
 158     _g1h = G1CollectedHeap::heap();
 159     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
 160   }
 161   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 162     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 163       _calls++;
 164       *card_ptr = 0;
 165     }
 166     return true;
 167   }
 168   int calls() { return _calls; }
 169 };
 170 
 171 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
 172 public:
 173   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 174     *card_ptr = CardTableModRefBS::dirty_card_val();
 175     return true;
 176   }
 177 };
 178 
 179 YoungList::YoungList(G1CollectedHeap* g1h) :
 180     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 181     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 182   guarantee(check_list_empty(false), "just making sure...");
 183 }
 184 
 185 void YoungList::push_region(HeapRegion *hr) {
 186   assert(!hr->is_young(), "should not already be young");
 187   assert(hr->get_next_young_region() == NULL, "cause it should!");
 188 
 189   hr->set_next_young_region(_head);
 190   _head = hr;
 191 
 192   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 193   ++_length;
 194 }
 195 
 196 void YoungList::add_survivor_region(HeapRegion* hr) {
 197   assert(hr->is_survivor(), "should be flagged as survivor region");
 198   assert(hr->get_next_young_region() == NULL, "cause it should!");
 199 
 200   hr->set_next_young_region(_survivor_head);
 201   if (_survivor_head == NULL) {
 202     _survivor_tail = hr;
 203   }
 204   _survivor_head = hr;
 205   ++_survivor_length;
 206 }
 207 
 208 void YoungList::empty_list(HeapRegion* list) {
 209   while (list != NULL) {
 210     HeapRegion* next = list->get_next_young_region();
 211     list->set_next_young_region(NULL);
 212     list->uninstall_surv_rate_group();
 213     list->set_not_young();
 214     list = next;
 215   }
 216 }
 217 
 218 void YoungList::empty_list() {
 219   assert(check_list_well_formed(), "young list should be well formed");
 220 
 221   empty_list(_head);
 222   _head = NULL;
 223   _length = 0;
 224 
 225   empty_list(_survivor_head);
 226   _survivor_head = NULL;
 227   _survivor_tail = NULL;
 228   _survivor_length = 0;
 229 
 230   _last_sampled_rs_lengths = 0;
 231 
 232   assert(check_list_empty(false), "just making sure...");
 233 }
 234 
 235 bool YoungList::check_list_well_formed() {
 236   bool ret = true;
 237 
 238   uint length = 0;
 239   HeapRegion* curr = _head;
 240   HeapRegion* last = NULL;
 241   while (curr != NULL) {
 242     if (!curr->is_young()) {
 243       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 244                              "incorrectly tagged (y: %d, surv: %d)",
 245                              curr->bottom(), curr->end(),
 246                              curr->is_young(), curr->is_survivor());
 247       ret = false;
 248     }
 249     ++length;
 250     last = curr;
 251     curr = curr->get_next_young_region();
 252   }
 253   ret = ret && (length == _length);
 254 
 255   if (!ret) {
 256     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 257     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 258                            length, _length);
 259   }
 260 
 261   return ret;
 262 }
 263 
 264 bool YoungList::check_list_empty(bool check_sample) {
 265   bool ret = true;
 266 
 267   if (_length != 0) {
 268     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 269                   _length);
 270     ret = false;
 271   }
 272   if (check_sample && _last_sampled_rs_lengths != 0) {
 273     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 274     ret = false;
 275   }
 276   if (_head != NULL) {
 277     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 278     ret = false;
 279   }
 280   if (!ret) {
 281     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 282   }
 283 
 284   return ret;
 285 }
 286 
 287 void
 288 YoungList::rs_length_sampling_init() {
 289   _sampled_rs_lengths = 0;
 290   _curr               = _head;
 291 }
 292 
 293 bool
 294 YoungList::rs_length_sampling_more() {
 295   return _curr != NULL;
 296 }
 297 
 298 void
 299 YoungList::rs_length_sampling_next() {
 300   assert( _curr != NULL, "invariant" );
 301   size_t rs_length = _curr->rem_set()->occupied();
 302 
 303   _sampled_rs_lengths += rs_length;
 304 
 305   // The current region may not yet have been added to the
 306   // incremental collection set (it gets added when it is
 307   // retired as the current allocation region).
 308   if (_curr->in_collection_set()) {
 309     // Update the collection set policy information for this region
 310     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 311   }
 312 
 313   _curr = _curr->get_next_young_region();
 314   if (_curr == NULL) {
 315     _last_sampled_rs_lengths = _sampled_rs_lengths;
 316     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 317   }
 318 }
 319 
 320 void
 321 YoungList::reset_auxilary_lists() {
 322   guarantee( is_empty(), "young list should be empty" );
 323   assert(check_list_well_formed(), "young list should be well formed");
 324 
 325   // Add survivor regions to SurvRateGroup.
 326   _g1h->g1_policy()->note_start_adding_survivor_regions();
 327   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 328 
 329   int young_index_in_cset = 0;
 330   for (HeapRegion* curr = _survivor_head;
 331        curr != NULL;
 332        curr = curr->get_next_young_region()) {
 333     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 334 
 335     // The region is a non-empty survivor so let's add it to
 336     // the incremental collection set for the next evacuation
 337     // pause.
 338     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 339     young_index_in_cset += 1;
 340   }
 341   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 342   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 343 
 344   _head   = _survivor_head;
 345   _length = _survivor_length;
 346   if (_survivor_head != NULL) {
 347     assert(_survivor_tail != NULL, "cause it shouldn't be");
 348     assert(_survivor_length > 0, "invariant");
 349     _survivor_tail->set_next_young_region(NULL);
 350   }
 351 
 352   // Don't clear the survivor list handles until the start of
 353   // the next evacuation pause - we need it in order to re-tag
 354   // the survivor regions from this evacuation pause as 'young'
 355   // at the start of the next.
 356 
 357   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 358 
 359   assert(check_list_well_formed(), "young list should be well formed");
 360 }
 361 
 362 void YoungList::print() {
 363   HeapRegion* lists[] = {_head,   _survivor_head};
 364   const char* names[] = {"YOUNG", "SURVIVOR"};
 365 
 366   for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
 367     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 368     HeapRegion *curr = lists[list];
 369     if (curr == NULL)
 370       gclog_or_tty->print_cr("  empty");
 371     while (curr != NULL) {
 372       gclog_or_tty->print_cr("  "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
 373                              HR_FORMAT_PARAMS(curr),
 374                              curr->prev_top_at_mark_start(),
 375                              curr->next_top_at_mark_start(),
 376                              curr->age_in_surv_rate_group_cond());
 377       curr = curr->get_next_young_region();
 378     }
 379   }
 380 
 381   gclog_or_tty->print_cr("");
 382 }
 383 
 384 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 385 {
 386   // Claim the right to put the region on the dirty cards region list
 387   // by installing a self pointer.
 388   HeapRegion* next = hr->get_next_dirty_cards_region();
 389   if (next == NULL) {
 390     HeapRegion* res = (HeapRegion*)
 391       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 392                           NULL);
 393     if (res == NULL) {
 394       HeapRegion* head;
 395       do {
 396         // Put the region to the dirty cards region list.
 397         head = _dirty_cards_region_list;
 398         next = (HeapRegion*)
 399           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 400         if (next == head) {
 401           assert(hr->get_next_dirty_cards_region() == hr,
 402                  "hr->get_next_dirty_cards_region() != hr");
 403           if (next == NULL) {
 404             // The last region in the list points to itself.
 405             hr->set_next_dirty_cards_region(hr);
 406           } else {
 407             hr->set_next_dirty_cards_region(next);
 408           }
 409         }
 410       } while (next != head);
 411     }
 412   }
 413 }
 414 
 415 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 416 {
 417   HeapRegion* head;
 418   HeapRegion* hr;
 419   do {
 420     head = _dirty_cards_region_list;
 421     if (head == NULL) {
 422       return NULL;
 423     }
 424     HeapRegion* new_head = head->get_next_dirty_cards_region();
 425     if (head == new_head) {
 426       // The last region.
 427       new_head = NULL;
 428     }
 429     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 430                                           head);
 431   } while (hr != head);
 432   assert(hr != NULL, "invariant");
 433   hr->set_next_dirty_cards_region(NULL);
 434   return hr;
 435 }
 436 
 437 void G1CollectedHeap::stop_conc_gc_threads() {
 438   _cg1r->stop();
 439   _cmThread->stop();
 440 }
 441 
 442 #ifdef ASSERT
 443 // A region is added to the collection set as it is retired
 444 // so an address p can point to a region which will be in the
 445 // collection set but has not yet been retired.  This method
 446 // therefore is only accurate during a GC pause after all
 447 // regions have been retired.  It is used for debugging
 448 // to check if an nmethod has references to objects that can
 449 // be move during a partial collection.  Though it can be
 450 // inaccurate, it is sufficient for G1 because the conservative
 451 // implementation of is_scavengable() for G1 will indicate that
 452 // all nmethods must be scanned during a partial collection.
 453 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
 454   HeapRegion* hr = heap_region_containing(p);
 455   return hr != NULL && hr->in_collection_set();
 456 }
 457 #endif
 458 
 459 // Returns true if the reference points to an object that
 460 // can move in an incremental collecction.
 461 bool G1CollectedHeap::is_scavengable(const void* p) {
 462   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 463   G1CollectorPolicy* g1p = g1h->g1_policy();
 464   HeapRegion* hr = heap_region_containing(p);
 465   if (hr == NULL) {
 466      // null
 467      assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
 468      return false;
 469   } else {
 470     return !hr->isHumongous();
 471   }
 472 }
 473 
 474 void G1CollectedHeap::check_ct_logs_at_safepoint() {
 475   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 476   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
 477 
 478   // Count the dirty cards at the start.
 479   CountNonCleanMemRegionClosure count1(this);
 480   ct_bs->mod_card_iterate(&count1);
 481   int orig_count = count1.n();
 482 
 483   // First clear the logged cards.
 484   ClearLoggedCardTableEntryClosure clear;
 485   dcqs.set_closure(&clear);
 486   dcqs.apply_closure_to_all_completed_buffers();
 487   dcqs.iterate_closure_all_threads(false);
 488   clear.print_histo();
 489 
 490   // Now ensure that there's no dirty cards.
 491   CountNonCleanMemRegionClosure count2(this);
 492   ct_bs->mod_card_iterate(&count2);
 493   if (count2.n() != 0) {
 494     gclog_or_tty->print_cr("Card table has %d entries; %d originally",
 495                            count2.n(), orig_count);
 496   }
 497   guarantee(count2.n() == 0, "Card table should be clean.");
 498 
 499   RedirtyLoggedCardTableEntryClosure redirty;
 500   JavaThread::dirty_card_queue_set().set_closure(&redirty);
 501   dcqs.apply_closure_to_all_completed_buffers();
 502   dcqs.iterate_closure_all_threads(false);
 503   gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
 504                          clear.calls(), orig_count);
 505   guarantee(redirty.calls() == clear.calls(),
 506             "Or else mechanism is broken.");
 507 
 508   CountNonCleanMemRegionClosure count3(this);
 509   ct_bs->mod_card_iterate(&count3);
 510   if (count3.n() != orig_count) {
 511     gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
 512                            orig_count, count3.n());
 513     guarantee(count3.n() >= orig_count, "Should have restored them all.");
 514   }
 515 
 516   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
 517 }
 518 
 519 // Private class members.
 520 
 521 G1CollectedHeap* G1CollectedHeap::_g1h;
 522 
 523 // Private methods.
 524 
 525 HeapRegion*
 526 G1CollectedHeap::new_region_try_secondary_free_list() {
 527   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 528   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 529     if (!_secondary_free_list.is_empty()) {
 530       if (G1ConcRegionFreeingVerbose) {
 531         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 532                                "secondary_free_list has %u entries",
 533                                _secondary_free_list.length());
 534       }
 535       // It looks as if there are free regions available on the
 536       // secondary_free_list. Let's move them to the free_list and try
 537       // again to allocate from it.
 538       append_secondary_free_list();
 539 
 540       assert(!_free_list.is_empty(), "if the secondary_free_list was not "
 541              "empty we should have moved at least one entry to the free_list");
 542       HeapRegion* res = _free_list.remove_head();
 543       if (G1ConcRegionFreeingVerbose) {
 544         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 545                                "allocated "HR_FORMAT" from secondary_free_list",
 546                                HR_FORMAT_PARAMS(res));
 547       }
 548       return res;
 549     }
 550 
 551     // Wait here until we get notifed either when (a) there are no
 552     // more free regions coming or (b) some regions have been moved on
 553     // the secondary_free_list.
 554     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 555   }
 556 
 557   if (G1ConcRegionFreeingVerbose) {
 558     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 559                            "could not allocate from secondary_free_list");
 560   }
 561   return NULL;
 562 }
 563 
 564 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
 565   assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
 566          "the only time we use this to allocate a humongous region is "
 567          "when we are allocating a single humongous region");
 568 
 569   HeapRegion* res;
 570   if (G1StressConcRegionFreeing) {
 571     if (!_secondary_free_list.is_empty()) {
 572       if (G1ConcRegionFreeingVerbose) {
 573         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 574                                "forced to look at the secondary_free_list");
 575       }
 576       res = new_region_try_secondary_free_list();
 577       if (res != NULL) {
 578         return res;
 579       }
 580     }
 581   }
 582   res = _free_list.remove_head_or_null();
 583   if (res == NULL) {
 584     if (G1ConcRegionFreeingVerbose) {
 585       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 586                              "res == NULL, trying the secondary_free_list");
 587     }
 588     res = new_region_try_secondary_free_list();
 589   }
 590   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 591     // Currently, only attempts to allocate GC alloc regions set
 592     // do_expand to true. So, we should only reach here during a
 593     // safepoint. If this assumption changes we might have to
 594     // reconsider the use of _expand_heap_after_alloc_failure.
 595     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 596 
 597     ergo_verbose1(ErgoHeapSizing,
 598                   "attempt heap expansion",
 599                   ergo_format_reason("region allocation request failed")
 600                   ergo_format_byte("allocation request"),
 601                   word_size * HeapWordSize);
 602     if (expand(word_size * HeapWordSize)) {
 603       // Given that expand() succeeded in expanding the heap, and we
 604       // always expand the heap by an amount aligned to the heap
 605       // region size, the free list should in theory not be empty. So
 606       // it would probably be OK to use remove_head(). But the extra
 607       // check for NULL is unlikely to be a performance issue here (we
 608       // just expanded the heap!) so let's just be conservative and
 609       // use remove_head_or_null().
 610       res = _free_list.remove_head_or_null();
 611     } else {
 612       _expand_heap_after_alloc_failure = false;
 613     }
 614   }
 615   return res;
 616 }
 617 
 618 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
 619                                                         size_t word_size) {
 620   assert(isHumongous(word_size), "word_size should be humongous");
 621   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 622 
 623   uint first = G1_NULL_HRS_INDEX;
 624   if (num_regions == 1) {
 625     // Only one region to allocate, no need to go through the slower
 626     // path. The caller will attempt the expasion if this fails, so
 627     // let's not try to expand here too.
 628     HeapRegion* hr = new_region(word_size, false /* do_expand */);
 629     if (hr != NULL) {
 630       first = hr->hrs_index();
 631     } else {
 632       first = G1_NULL_HRS_INDEX;
 633     }
 634   } else {
 635     // We can't allocate humongous regions while cleanupComplete() is
 636     // running, since some of the regions we find to be empty might not
 637     // yet be added to the free list and it is not straightforward to
 638     // know which list they are on so that we can remove them. Note
 639     // that we only need to do this if we need to allocate more than
 640     // one region to satisfy the current humongous allocation
 641     // request. If we are only allocating one region we use the common
 642     // region allocation code (see above).
 643     wait_while_free_regions_coming();
 644     append_secondary_free_list_if_not_empty_with_lock();
 645 
 646     if (free_regions() >= num_regions) {
 647       first = _hrs.find_contiguous(num_regions);
 648       if (first != G1_NULL_HRS_INDEX) {
 649         for (uint i = first; i < first + num_regions; ++i) {
 650           HeapRegion* hr = region_at(i);
 651           assert(hr->is_empty(), "sanity");
 652           assert(is_on_master_free_list(hr), "sanity");
 653           hr->set_pending_removal(true);
 654         }
 655         _free_list.remove_all_pending(num_regions);
 656       }
 657     }
 658   }
 659   return first;
 660 }
 661 
 662 HeapWord*
 663 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 664                                                            uint num_regions,
 665                                                            size_t word_size) {
 666   assert(first != G1_NULL_HRS_INDEX, "pre-condition");
 667   assert(isHumongous(word_size), "word_size should be humongous");
 668   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 669 
 670   // Index of last region in the series + 1.
 671   uint last = first + num_regions;
 672 
 673   // We need to initialize the region(s) we just discovered. This is
 674   // a bit tricky given that it can happen concurrently with
 675   // refinement threads refining cards on these regions and
 676   // potentially wanting to refine the BOT as they are scanning
 677   // those cards (this can happen shortly after a cleanup; see CR
 678   // 6991377). So we have to set up the region(s) carefully and in
 679   // a specific order.
 680 
 681   // The word size sum of all the regions we will allocate.
 682   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 683   assert(word_size <= word_size_sum, "sanity");
 684 
 685   // This will be the "starts humongous" region.
 686   HeapRegion* first_hr = region_at(first);
 687   // The header of the new object will be placed at the bottom of
 688   // the first region.
 689   HeapWord* new_obj = first_hr->bottom();
 690   // This will be the new end of the first region in the series that
 691   // should also match the end of the last region in the seriers.
 692   HeapWord* new_end = new_obj + word_size_sum;
 693   // This will be the new top of the first region that will reflect
 694   // this allocation.
 695   HeapWord* new_top = new_obj + word_size;
 696 
 697   // First, we need to zero the header of the space that we will be
 698   // allocating. When we update top further down, some refinement
 699   // threads might try to scan the region. By zeroing the header we
 700   // ensure that any thread that will try to scan the region will
 701   // come across the zero klass word and bail out.
 702   //
 703   // NOTE: It would not have been correct to have used
 704   // CollectedHeap::fill_with_object() and make the space look like
 705   // an int array. The thread that is doing the allocation will
 706   // later update the object header to a potentially different array
 707   // type and, for a very short period of time, the klass and length
 708   // fields will be inconsistent. This could cause a refinement
 709   // thread to calculate the object size incorrectly.
 710   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 711 
 712   // We will set up the first region as "starts humongous". This
 713   // will also update the BOT covering all the regions to reflect
 714   // that there is a single object that starts at the bottom of the
 715   // first region.
 716   first_hr->set_startsHumongous(new_top, new_end);
 717 
 718   // Then, if there are any, we will set up the "continues
 719   // humongous" regions.
 720   HeapRegion* hr = NULL;
 721   for (uint i = first + 1; i < last; ++i) {
 722     hr = region_at(i);
 723     hr->set_continuesHumongous(first_hr);
 724   }
 725   // If we have "continues humongous" regions (hr != NULL), then the
 726   // end of the last one should match new_end.
 727   assert(hr == NULL || hr->end() == new_end, "sanity");
 728 
 729   // Up to this point no concurrent thread would have been able to
 730   // do any scanning on any region in this series. All the top
 731   // fields still point to bottom, so the intersection between
 732   // [bottom,top] and [card_start,card_end] will be empty. Before we
 733   // update the top fields, we'll do a storestore to make sure that
 734   // no thread sees the update to top before the zeroing of the
 735   // object header and the BOT initialization.
 736   OrderAccess::storestore();
 737 
 738   // Now that the BOT and the object header have been initialized,
 739   // we can update top of the "starts humongous" region.
 740   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 741          "new_top should be in this region");
 742   first_hr->set_top(new_top);
 743   if (_hr_printer.is_active()) {
 744     HeapWord* bottom = first_hr->bottom();
 745     HeapWord* end = first_hr->orig_end();
 746     if ((first + 1) == last) {
 747       // the series has a single humongous region
 748       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 749     } else {
 750       // the series has more than one humongous regions
 751       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 752     }
 753   }
 754 
 755   // Now, we will update the top fields of the "continues humongous"
 756   // regions. The reason we need to do this is that, otherwise,
 757   // these regions would look empty and this will confuse parts of
 758   // G1. For example, the code that looks for a consecutive number
 759   // of empty regions will consider them empty and try to
 760   // re-allocate them. We can extend is_empty() to also include
 761   // !continuesHumongous(), but it is easier to just update the top
 762   // fields here. The way we set top for all regions (i.e., top ==
 763   // end for all regions but the last one, top == new_top for the
 764   // last one) is actually used when we will free up the humongous
 765   // region in free_humongous_region().
 766   hr = NULL;
 767   for (uint i = first + 1; i < last; ++i) {
 768     hr = region_at(i);
 769     if ((i + 1) == last) {
 770       // last continues humongous region
 771       assert(hr->bottom() < new_top && new_top <= hr->end(),
 772              "new_top should fall on this region");
 773       hr->set_top(new_top);
 774       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 775     } else {
 776       // not last one
 777       assert(new_top > hr->end(), "new_top should be above this region");
 778       hr->set_top(hr->end());
 779       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 780     }
 781   }
 782   // If we have continues humongous regions (hr != NULL), then the
 783   // end of the last one should match new_end and its top should
 784   // match new_top.
 785   assert(hr == NULL ||
 786          (hr->end() == new_end && hr->top() == new_top), "sanity");
 787 
 788   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 789   _summary_bytes_used += first_hr->used();
 790   _humongous_set.add(first_hr);
 791 
 792   return new_obj;
 793 }
 794 
 795 // If could fit into free regions w/o expansion, try.
 796 // Otherwise, if can expand, do so.
 797 // Otherwise, if using ex regions might help, try with ex given back.
 798 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 799   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 800 
 801   verify_region_sets_optional();
 802 
 803   size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
 804   uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
 805   uint x_num = expansion_regions();
 806   uint fs = _hrs.free_suffix();
 807   uint first = humongous_obj_allocate_find_first(num_regions, word_size);
 808   if (first == G1_NULL_HRS_INDEX) {
 809     // The only thing we can do now is attempt expansion.
 810     if (fs + x_num >= num_regions) {
 811       // If the number of regions we're trying to allocate for this
 812       // object is at most the number of regions in the free suffix,
 813       // then the call to humongous_obj_allocate_find_first() above
 814       // should have succeeded and we wouldn't be here.
 815       //
 816       // We should only be trying to expand when the free suffix is
 817       // not sufficient for the object _and_ we have some expansion
 818       // room available.
 819       assert(num_regions > fs, "earlier allocation should have succeeded");
 820 
 821       ergo_verbose1(ErgoHeapSizing,
 822                     "attempt heap expansion",
 823                     ergo_format_reason("humongous allocation request failed")
 824                     ergo_format_byte("allocation request"),
 825                     word_size * HeapWordSize);
 826       if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
 827         // Even though the heap was expanded, it might not have
 828         // reached the desired size. So, we cannot assume that the
 829         // allocation will succeed.
 830         first = humongous_obj_allocate_find_first(num_regions, word_size);
 831       }
 832     }
 833   }
 834 
 835   HeapWord* result = NULL;
 836   if (first != G1_NULL_HRS_INDEX) {
 837     result =
 838       humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
 839     assert(result != NULL, "it should always return a valid result");
 840 
 841     // A successful humongous object allocation changes the used space
 842     // information of the old generation so we need to recalculate the
 843     // sizes and update the jstat counters here.
 844     g1mm()->update_sizes();
 845   }
 846 
 847   verify_region_sets_optional();
 848 
 849   return result;
 850 }
 851 
 852 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 853   assert_heap_not_locked_and_not_at_safepoint();
 854   assert(!isHumongous(word_size), "we do not allow humongous TLABs");
 855 
 856   unsigned int dummy_gc_count_before;
 857   return attempt_allocation(word_size, &dummy_gc_count_before);
 858 }
 859 
 860 HeapWord*
 861 G1CollectedHeap::mem_allocate(size_t word_size,
 862                               bool*  gc_overhead_limit_was_exceeded) {
 863   assert_heap_not_locked_and_not_at_safepoint();
 864 
 865   // Loop until the allocation is satisified, or unsatisfied after GC.
 866   for (int try_count = 1; /* we'll return */; try_count += 1) {
 867     unsigned int gc_count_before;
 868 
 869     HeapWord* result = NULL;
 870     if (!isHumongous(word_size)) {
 871       result = attempt_allocation(word_size, &gc_count_before);
 872     } else {
 873       result = attempt_allocation_humongous(word_size, &gc_count_before);
 874     }
 875     if (result != NULL) {
 876       return result;
 877     }
 878 
 879     // Create the garbage collection operation...
 880     VM_G1CollectForAllocation op(gc_count_before, word_size);
 881     // ...and get the VM thread to execute it.
 882     VMThread::execute(&op);
 883 
 884     if (op.prologue_succeeded() && op.pause_succeeded()) {
 885       // If the operation was successful we'll return the result even
 886       // if it is NULL. If the allocation attempt failed immediately
 887       // after a Full GC, it's unlikely we'll be able to allocate now.
 888       HeapWord* result = op.result();
 889       if (result != NULL && !isHumongous(word_size)) {
 890         // Allocations that take place on VM operations do not do any
 891         // card dirtying and we have to do it here. We only have to do
 892         // this for non-humongous allocations, though.
 893         dirty_young_block(result, word_size);
 894       }
 895       return result;
 896     } else {
 897       assert(op.result() == NULL,
 898              "the result should be NULL if the VM op did not succeed");
 899     }
 900 
 901     // Give a warning if we seem to be looping forever.
 902     if ((QueuedAllocationWarningCount > 0) &&
 903         (try_count % QueuedAllocationWarningCount == 0)) {
 904       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 905     }
 906   }
 907 
 908   ShouldNotReachHere();
 909   return NULL;
 910 }
 911 
 912 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 913                                            unsigned int *gc_count_before_ret) {
 914   // Make sure you read the note in attempt_allocation_humongous().
 915 
 916   assert_heap_not_locked_and_not_at_safepoint();
 917   assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
 918          "be called for humongous allocation requests");
 919 
 920   // We should only get here after the first-level allocation attempt
 921   // (attempt_allocation()) failed to allocate.
 922 
 923   // We will loop until a) we manage to successfully perform the
 924   // allocation or b) we successfully schedule a collection which
 925   // fails to perform the allocation. b) is the only case when we'll
 926   // return NULL.
 927   HeapWord* result = NULL;
 928   for (int try_count = 1; /* we'll return */; try_count += 1) {
 929     bool should_try_gc;
 930     unsigned int gc_count_before;
 931 
 932     {
 933       MutexLockerEx x(Heap_lock);
 934 
 935       result = _mutator_alloc_region.attempt_allocation_locked(word_size,
 936                                                       false /* bot_updates */);
 937       if (result != NULL) {
 938         return result;
 939       }
 940 
 941       // If we reach here, attempt_allocation_locked() above failed to
 942       // allocate a new region. So the mutator alloc region should be NULL.
 943       assert(_mutator_alloc_region.get() == NULL, "only way to get here");
 944 
 945       if (GC_locker::is_active_and_needs_gc()) {
 946         if (g1_policy()->can_expand_young_list()) {
 947           // No need for an ergo verbose message here,
 948           // can_expand_young_list() does this when it returns true.
 949           result = _mutator_alloc_region.attempt_allocation_force(word_size,
 950                                                       false /* bot_updates */);
 951           if (result != NULL) {
 952             return result;
 953           }
 954         }
 955         should_try_gc = false;
 956       } else {
 957         // The GCLocker may not be active but the GCLocker initiated
 958         // GC may not yet have been performed (GCLocker::needs_gc()
 959         // returns true). In this case we do not try this GC and
 960         // wait until the GCLocker initiated GC is performed, and
 961         // then retry the allocation.
 962         if (GC_locker::needs_gc()) {
 963           should_try_gc = false;
 964         } else {
 965           // Read the GC count while still holding the Heap_lock.
 966           gc_count_before = total_collections();
 967           should_try_gc = true;
 968         }
 969       }
 970     }
 971 
 972     if (should_try_gc) {
 973       bool succeeded;
 974       result = do_collection_pause(word_size, gc_count_before, &succeeded);
 975       if (result != NULL) {
 976         assert(succeeded, "only way to get back a non-NULL result");
 977         return result;
 978       }
 979 
 980       if (succeeded) {
 981         // If we get here we successfully scheduled a collection which
 982         // failed to allocate. No point in trying to allocate
 983         // further. We'll just return NULL.
 984         MutexLockerEx x(Heap_lock);
 985         *gc_count_before_ret = total_collections();
 986         return NULL;
 987       }
 988     } else {
 989       // The GCLocker is either active or the GCLocker initiated
 990       // GC has not yet been performed. Stall until it is and
 991       // then retry the allocation.
 992       GC_locker::stall_until_clear();
 993     }
 994 
 995     // We can reach here if we were unsuccessul in scheduling a
 996     // collection (because another thread beat us to it) or if we were
 997     // stalled due to the GC locker. In either can we should retry the
 998     // allocation attempt in case another thread successfully
 999     // performed a collection and reclaimed enough space. We do the
1000     // first attempt (without holding the Heap_lock) here and the
1001     // follow-on attempt will be at the start of the next loop
1002     // iteration (after taking the Heap_lock).
1003     result = _mutator_alloc_region.attempt_allocation(word_size,
1004                                                       false /* bot_updates */);
1005     if (result != NULL) {
1006       return result;
1007     }
1008 
1009     // Give a warning if we seem to be looping forever.
1010     if ((QueuedAllocationWarningCount > 0) &&
1011         (try_count % QueuedAllocationWarningCount == 0)) {
1012       warning("G1CollectedHeap::attempt_allocation_slow() "
1013               "retries %d times", try_count);
1014     }
1015   }
1016 
1017   ShouldNotReachHere();
1018   return NULL;
1019 }
1020 
1021 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1022                                           unsigned int * gc_count_before_ret) {
1023   // The structure of this method has a lot of similarities to
1024   // attempt_allocation_slow(). The reason these two were not merged
1025   // into a single one is that such a method would require several "if
1026   // allocation is not humongous do this, otherwise do that"
1027   // conditional paths which would obscure its flow. In fact, an early
1028   // version of this code did use a unified method which was harder to
1029   // follow and, as a result, it had subtle bugs that were hard to
1030   // track down. So keeping these two methods separate allows each to
1031   // be more readable. It will be good to keep these two in sync as
1032   // much as possible.
1033 
1034   assert_heap_not_locked_and_not_at_safepoint();
1035   assert(isHumongous(word_size), "attempt_allocation_humongous() "
1036          "should only be called for humongous allocations");
1037 
1038   // Humongous objects can exhaust the heap quickly, so we should check if we
1039   // need to start a marking cycle at each humongous object allocation. We do
1040   // the check before we do the actual allocation. The reason for doing it
1041   // before the allocation is that we avoid having to keep track of the newly
1042   // allocated memory while we do a GC.
1043   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1044                                            word_size)) {
1045     collect(GCCause::_g1_humongous_allocation);
1046   }
1047 
1048   // We will loop until a) we manage to successfully perform the
1049   // allocation or b) we successfully schedule a collection which
1050   // fails to perform the allocation. b) is the only case when we'll
1051   // return NULL.
1052   HeapWord* result = NULL;
1053   for (int try_count = 1; /* we'll return */; try_count += 1) {
1054     bool should_try_gc;
1055     unsigned int gc_count_before;
1056 
1057     {
1058       MutexLockerEx x(Heap_lock);
1059 
1060       // Given that humongous objects are not allocated in young
1061       // regions, we'll first try to do the allocation without doing a
1062       // collection hoping that there's enough space in the heap.
1063       result = humongous_obj_allocate(word_size);
1064       if (result != NULL) {
1065         return result;
1066       }
1067 
1068       if (GC_locker::is_active_and_needs_gc()) {
1069         should_try_gc = false;
1070       } else {
1071          // The GCLocker may not be active but the GCLocker initiated
1072         // GC may not yet have been performed (GCLocker::needs_gc()
1073         // returns true). In this case we do not try this GC and
1074         // wait until the GCLocker initiated GC is performed, and
1075         // then retry the allocation.
1076         if (GC_locker::needs_gc()) {
1077           should_try_gc = false;
1078         } else {
1079           // Read the GC count while still holding the Heap_lock.
1080           gc_count_before = total_collections();
1081           should_try_gc = true;
1082         }
1083       }
1084     }
1085 
1086     if (should_try_gc) {
1087       // If we failed to allocate the humongous object, we should try to
1088       // do a collection pause (if we're allowed) in case it reclaims
1089       // enough space for the allocation to succeed after the pause.
1090 
1091       bool succeeded;
1092       result = do_collection_pause(word_size, gc_count_before, &succeeded);
1093       if (result != NULL) {
1094         assert(succeeded, "only way to get back a non-NULL result");
1095         return result;
1096       }
1097 
1098       if (succeeded) {
1099         // If we get here we successfully scheduled a collection which
1100         // failed to allocate. No point in trying to allocate
1101         // further. We'll just return NULL.
1102         MutexLockerEx x(Heap_lock);
1103         *gc_count_before_ret = total_collections();
1104         return NULL;
1105       }
1106     } else {
1107       // The GCLocker is either active or the GCLocker initiated
1108       // GC has not yet been performed. Stall until it is and
1109       // then retry the allocation.
1110       GC_locker::stall_until_clear();
1111     }
1112 
1113     // We can reach here if we were unsuccessul in scheduling a
1114     // collection (because another thread beat us to it) or if we were
1115     // stalled due to the GC locker. In either can we should retry the
1116     // allocation attempt in case another thread successfully
1117     // performed a collection and reclaimed enough space.  Give a
1118     // warning if we seem to be looping forever.
1119 
1120     if ((QueuedAllocationWarningCount > 0) &&
1121         (try_count % QueuedAllocationWarningCount == 0)) {
1122       warning("G1CollectedHeap::attempt_allocation_humongous() "
1123               "retries %d times", try_count);
1124     }
1125   }
1126 
1127   ShouldNotReachHere();
1128   return NULL;
1129 }
1130 
1131 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1132                                        bool expect_null_mutator_alloc_region) {
1133   assert_at_safepoint(true /* should_be_vm_thread */);
1134   assert(_mutator_alloc_region.get() == NULL ||
1135                                              !expect_null_mutator_alloc_region,
1136          "the current alloc region was unexpectedly found to be non-NULL");
1137 
1138   if (!isHumongous(word_size)) {
1139     return _mutator_alloc_region.attempt_allocation_locked(word_size,
1140                                                       false /* bot_updates */);
1141   } else {
1142     HeapWord* result = humongous_obj_allocate(word_size);
1143     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1144       g1_policy()->set_initiate_conc_mark_if_possible();
1145     }
1146     return result;
1147   }
1148 
1149   ShouldNotReachHere();
1150 }
1151 
1152 class PostMCRemSetClearClosure: public HeapRegionClosure {
1153   G1CollectedHeap* _g1h;
1154   ModRefBarrierSet* _mr_bs;
1155 public:
1156   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1157     _g1h(g1h), _mr_bs(mr_bs) { }
1158   bool doHeapRegion(HeapRegion* r) {
1159     if (r->continuesHumongous()) {
1160       return false;
1161     }
1162     _g1h->reset_gc_time_stamps(r);
1163     HeapRegionRemSet* hrrs = r->rem_set();
1164     if (hrrs != NULL) hrrs->clear();
1165     // You might think here that we could clear just the cards
1166     // corresponding to the used region.  But no: if we leave a dirty card
1167     // in a region we might allocate into, then it would prevent that card
1168     // from being enqueued, and cause it to be missed.
1169     // Re: the performance cost: we shouldn't be doing full GC anyway!
1170     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1171     return false;
1172   }
1173 };
1174 
1175 void G1CollectedHeap::clear_rsets_post_compaction() {
1176   PostMCRemSetClearClosure rs_clear(this, mr_bs());
1177   heap_region_iterate(&rs_clear);
1178 }
1179 
1180 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1181   G1CollectedHeap*   _g1h;
1182   UpdateRSOopClosure _cl;
1183   int                _worker_i;
1184 public:
1185   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1186     _cl(g1->g1_rem_set(), worker_i),
1187     _worker_i(worker_i),
1188     _g1h(g1)
1189   { }
1190 
1191   bool doHeapRegion(HeapRegion* r) {
1192     if (!r->continuesHumongous()) {
1193       _cl.set_from(r);
1194       r->oop_iterate(&_cl);
1195     }
1196     return false;
1197   }
1198 };
1199 
1200 class ParRebuildRSTask: public AbstractGangTask {
1201   G1CollectedHeap* _g1;
1202 public:
1203   ParRebuildRSTask(G1CollectedHeap* g1)
1204     : AbstractGangTask("ParRebuildRSTask"),
1205       _g1(g1)
1206   { }
1207 
1208   void work(uint worker_id) {
1209     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1210     _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1211                                           _g1->workers()->active_workers(),
1212                                          HeapRegion::RebuildRSClaimValue);
1213   }
1214 };
1215 
1216 class PostCompactionPrinterClosure: public HeapRegionClosure {
1217 private:
1218   G1HRPrinter* _hr_printer;
1219 public:
1220   bool doHeapRegion(HeapRegion* hr) {
1221     assert(!hr->is_young(), "not expecting to find young regions");
1222     // We only generate output for non-empty regions.
1223     if (!hr->is_empty()) {
1224       if (!hr->isHumongous()) {
1225         _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1226       } else if (hr->startsHumongous()) {
1227         if (hr->region_num() == 1) {
1228           // single humongous region
1229           _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1230         } else {
1231           _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1232         }
1233       } else {
1234         assert(hr->continuesHumongous(), "only way to get here");
1235         _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1236       }
1237     }
1238     return false;
1239   }
1240 
1241   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1242     : _hr_printer(hr_printer) { }
1243 };
1244 
1245 void G1CollectedHeap::print_hrs_post_compaction() {
1246   PostCompactionPrinterClosure cl(hr_printer());
1247   heap_region_iterate(&cl);
1248 }
1249 
1250 double G1CollectedHeap::verify(bool guard, const char* msg) {
1251   double verify_time_ms = 0.0;
1252 
1253   if (guard && total_collections() >= VerifyGCStartAt) {
1254     double verify_start = os::elapsedTime();
1255     HandleMark hm;  // Discard invalid handles created during verification
1256     gclog_or_tty->print(msg);
1257     prepare_for_verify();
1258     Universe::verify(false /* silent */, VerifyOption_G1UsePrevMarking);
1259     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
1260   }
1261 
1262   return verify_time_ms;
1263 }
1264 
1265 void G1CollectedHeap::verify_before_gc() {
1266   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
1267   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
1268 }
1269 
1270 void G1CollectedHeap::verify_after_gc() {
1271   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
1272   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
1273 }
1274 
1275 bool G1CollectedHeap::do_collection(bool explicit_gc,
1276                                     bool clear_all_soft_refs,
1277                                     size_t word_size) {
1278   assert_at_safepoint(true /* should_be_vm_thread */);
1279 
1280   if (GC_locker::check_active_before_gc()) {
1281     return false;
1282   }
1283 
1284   SvcGCMarker sgcm(SvcGCMarker::FULL);
1285   ResourceMark rm;
1286 
1287   print_heap_before_gc();
1288 
1289   size_t metadata_prev_used = MetaspaceAux::used_in_bytes();
1290 
1291   HRSPhaseSetter x(HRSPhaseFullGC);
1292   verify_region_sets_optional();
1293 
1294   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1295                            collector_policy()->should_clear_all_soft_refs();
1296 
1297   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1298 
1299   {
1300     IsGCActiveMark x;
1301 
1302     // Timing
1303     assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1304     gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1305     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1306 
1307     TraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, gclog_or_tty);
1308     TraceCollectorStats tcs(g1mm()->full_collection_counters());
1309     TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1310 
1311     double start = os::elapsedTime();
1312     g1_policy()->record_full_collection_start();
1313 
1314     // Note: When we have a more flexible GC logging framework that
1315     // allows us to add optional attributes to a GC log record we
1316     // could consider timing and reporting how long we wait in the
1317     // following two methods.
1318     wait_while_free_regions_coming();
1319     // If we start the compaction before the CM threads finish
1320     // scanning the root regions we might trip them over as we'll
1321     // be moving objects / updating references. So let's wait until
1322     // they are done. By telling them to abort, they should complete
1323     // early.
1324     _cm->root_regions()->abort();
1325     _cm->root_regions()->wait_until_scan_finished();
1326     append_secondary_free_list_if_not_empty_with_lock();
1327 
1328     gc_prologue(true);
1329     increment_total_collections(true /* full gc */);
1330     increment_old_marking_cycles_started();
1331 
1332     size_t g1h_prev_used = used();
1333     assert(used() == recalculate_used(), "Should be equal");
1334 
1335     verify_before_gc();
1336 
1337     pre_full_gc_dump();
1338 
1339     COMPILER2_PRESENT(DerivedPointerTable::clear());
1340 
1341     // Disable discovery and empty the discovered lists
1342     // for the CM ref processor.
1343     ref_processor_cm()->disable_discovery();
1344     ref_processor_cm()->abandon_partial_discovery();
1345     ref_processor_cm()->verify_no_references_recorded();
1346 
1347     // Abandon current iterations of concurrent marking and concurrent
1348     // refinement, if any are in progress. We have to do this before
1349     // wait_until_scan_finished() below.
1350     concurrent_mark()->abort();
1351 
1352     // Make sure we'll choose a new allocation region afterwards.
1353     release_mutator_alloc_region();
1354     abandon_gc_alloc_regions();
1355     g1_rem_set()->cleanupHRRS();
1356 
1357     // We should call this after we retire any currently active alloc
1358     // regions so that all the ALLOC / RETIRE events are generated
1359     // before the start GC event.
1360     _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1361 
1362     // We may have added regions to the current incremental collection
1363     // set between the last GC or pause and now. We need to clear the
1364     // incremental collection set and then start rebuilding it afresh
1365     // after this full GC.
1366     abandon_collection_set(g1_policy()->inc_cset_head());
1367     g1_policy()->clear_incremental_cset();
1368     g1_policy()->stop_incremental_cset_building();
1369 
1370     tear_down_region_sets(false /* free_list_only */);
1371     g1_policy()->set_gcs_are_young(true);
1372 
1373     // See the comments in g1CollectedHeap.hpp and
1374     // G1CollectedHeap::ref_processing_init() about
1375     // how reference processing currently works in G1.
1376 
1377     // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1378     ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1379 
1380     // Temporarily clear the STW ref processor's _is_alive_non_header field.
1381     ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1382 
1383     ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1384     ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1385 
1386     // Do collection work
1387     {
1388       HandleMark hm;  // Discard invalid handles created during gc
1389       G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1390     }
1391 
1392     assert(free_regions() == 0, "we should not have added any free regions");
1393     rebuild_region_sets(false /* free_list_only */);
1394 
1395     // Enqueue any discovered reference objects that have
1396     // not been removed from the discovered lists.
1397     ref_processor_stw()->enqueue_discovered_references();
1398 
1399     COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1400 
1401     MemoryService::track_memory_usage();
1402 
1403     verify_after_gc();
1404 
1405     assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1406     ref_processor_stw()->verify_no_references_recorded();
1407 
1408     // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1409     ClassLoaderDataGraph::purge();
1410 
1411     // Note: since we've just done a full GC, concurrent
1412     // marking is no longer active. Therefore we need not
1413     // re-enable reference discovery for the CM ref processor.
1414     // That will be done at the start of the next marking cycle.
1415     assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1416     ref_processor_cm()->verify_no_references_recorded();
1417 
1418     reset_gc_time_stamp();
1419     // Since everything potentially moved, we will clear all remembered
1420     // sets, and clear all cards.  Later we will rebuild remebered
1421     // sets. We will also reset the GC time stamps of the regions.
1422     clear_rsets_post_compaction();
1423     check_gc_time_stamps();
1424 
1425     // Resize the heap if necessary.
1426     resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1427 
1428     if (_hr_printer.is_active()) {
1429       // We should do this after we potentially resize the heap so
1430       // that all the COMMIT / UNCOMMIT events are generated before
1431       // the end GC event.
1432 
1433       print_hrs_post_compaction();
1434       _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1435     }
1436 
1437     if (_cg1r->use_cache()) {
1438       _cg1r->clear_and_record_card_counts();
1439       _cg1r->clear_hot_cache();
1440     }
1441 
1442     // Rebuild remembered sets of all regions.
1443     if (G1CollectedHeap::use_parallel_gc_threads()) {
1444       uint n_workers =
1445         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1446                                        workers()->active_workers(),
1447                                        Threads::number_of_non_daemon_threads());
1448       assert(UseDynamicNumberOfGCThreads ||
1449              n_workers == workers()->total_workers(),
1450              "If not dynamic should be using all the  workers");
1451       workers()->set_active_workers(n_workers);
1452       // Set parallel threads in the heap (_n_par_threads) only
1453       // before a parallel phase and always reset it to 0 after
1454       // the phase so that the number of parallel threads does
1455       // no get carried forward to a serial phase where there
1456       // may be code that is "possibly_parallel".
1457       set_par_threads(n_workers);
1458 
1459       ParRebuildRSTask rebuild_rs_task(this);
1460       assert(check_heap_region_claim_values(
1461              HeapRegion::InitialClaimValue), "sanity check");
1462       assert(UseDynamicNumberOfGCThreads ||
1463              workers()->active_workers() == workers()->total_workers(),
1464         "Unless dynamic should use total workers");
1465       // Use the most recent number of  active workers
1466       assert(workers()->active_workers() > 0,
1467         "Active workers not properly set");
1468       set_par_threads(workers()->active_workers());
1469       workers()->run_task(&rebuild_rs_task);
1470       set_par_threads(0);
1471       assert(check_heap_region_claim_values(
1472              HeapRegion::RebuildRSClaimValue), "sanity check");
1473       reset_heap_region_claim_values();
1474     } else {
1475       RebuildRSOutOfRegionClosure rebuild_rs(this);
1476       heap_region_iterate(&rebuild_rs);
1477     }
1478 
1479     if (G1Log::fine()) {
1480       print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1481     }
1482 
1483     if (true) { // FIXME
1484       MetaspaceGC::compute_new_size();
1485     }
1486 
1487     // Start a new incremental collection set for the next pause
1488     assert(g1_policy()->collection_set() == NULL, "must be");
1489     g1_policy()->start_incremental_cset_building();
1490 
1491     // Clear the _cset_fast_test bitmap in anticipation of adding
1492     // regions to the incremental collection set for the next
1493     // evacuation pause.
1494     clear_cset_fast_test();
1495 
1496     init_mutator_alloc_region();
1497 
1498     double end = os::elapsedTime();
1499     g1_policy()->record_full_collection_end();
1500 
1501 #ifdef TRACESPINNING
1502     ParallelTaskTerminator::print_termination_counts();
1503 #endif
1504 
1505     gc_epilogue(true);
1506 
1507     // Discard all rset updates
1508     JavaThread::dirty_card_queue_set().abandon_logs();
1509     assert(!G1DeferredRSUpdate
1510            || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1511 
1512     _young_list->reset_sampled_info();
1513     // At this point there should be no regions in the
1514     // entire heap tagged as young.
1515     assert( check_young_list_empty(true /* check_heap */),
1516       "young list should be empty at this point");
1517 
1518     // Update the number of full collections that have been completed.
1519     increment_old_marking_cycles_completed(false /* concurrent */);
1520 
1521     _hrs.verify_optional();
1522     verify_region_sets_optional();
1523 
1524     print_heap_after_gc();
1525 
1526     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1527     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1528     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1529     // before any GC notifications are raised.
1530     g1mm()->update_sizes();
1531   }
1532 
1533   post_full_gc_dump();
1534 
1535   return true;
1536 }
1537 
1538 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1539   // do_collection() will return whether it succeeded in performing
1540   // the GC. Currently, there is no facility on the
1541   // do_full_collection() API to notify the caller than the collection
1542   // did not succeed (e.g., because it was locked out by the GC
1543   // locker). So, right now, we'll ignore the return value.
1544   bool dummy = do_collection(true,                /* explicit_gc */
1545                              clear_all_soft_refs,
1546                              0                    /* word_size */);
1547 }
1548 
1549 // This code is mostly copied from TenuredGeneration.
1550 void
1551 G1CollectedHeap::
1552 resize_if_necessary_after_full_collection(size_t word_size) {
1553   assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1554 
1555   // Include the current allocation, if any, and bytes that will be
1556   // pre-allocated to support collections, as "used".
1557   const size_t used_after_gc = used();
1558   const size_t capacity_after_gc = capacity();
1559   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1560 
1561   // This is enforced in arguments.cpp.
1562   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1563          "otherwise the code below doesn't make sense");
1564 
1565   // We don't have floating point command-line arguments
1566   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1567   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1568   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1569   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1570 
1571   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1572   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1573 
1574   // We have to be careful here as these two calculations can overflow
1575   // 32-bit size_t's.
1576   double used_after_gc_d = (double) used_after_gc;
1577   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1578   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1579 
1580   // Let's make sure that they are both under the max heap size, which
1581   // by default will make them fit into a size_t.
1582   double desired_capacity_upper_bound = (double) max_heap_size;
1583   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1584                                     desired_capacity_upper_bound);
1585   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1586                                     desired_capacity_upper_bound);
1587 
1588   // We can now safely turn them into size_t's.
1589   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1590   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1591 
1592   // This assert only makes sense here, before we adjust them
1593   // with respect to the min and max heap size.
1594   assert(minimum_desired_capacity <= maximum_desired_capacity,
1595          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1596                  "maximum_desired_capacity = "SIZE_FORMAT,
1597                  minimum_desired_capacity, maximum_desired_capacity));
1598 
1599   // Should not be greater than the heap max size. No need to adjust
1600   // it with respect to the heap min size as it's a lower bound (i.e.,
1601   // we'll try to make the capacity larger than it, not smaller).
1602   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1603   // Should not be less than the heap min size. No need to adjust it
1604   // with respect to the heap max size as it's an upper bound (i.e.,
1605   // we'll try to make the capacity smaller than it, not greater).
1606   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1607 
1608   if (capacity_after_gc < minimum_desired_capacity) {
1609     // Don't expand unless it's significant
1610     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1611     ergo_verbose4(ErgoHeapSizing,
1612                   "attempt heap expansion",
1613                   ergo_format_reason("capacity lower than "
1614                                      "min desired capacity after Full GC")
1615                   ergo_format_byte("capacity")
1616                   ergo_format_byte("occupancy")
1617                   ergo_format_byte_perc("min desired capacity"),
1618                   capacity_after_gc, used_after_gc,
1619                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1620     expand(expand_bytes);
1621 
1622     // No expansion, now see if we want to shrink
1623   } else if (capacity_after_gc > maximum_desired_capacity) {
1624     // Capacity too large, compute shrinking size
1625     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1626     ergo_verbose4(ErgoHeapSizing,
1627                   "attempt heap shrinking",
1628                   ergo_format_reason("capacity higher than "
1629                                      "max desired capacity after Full GC")
1630                   ergo_format_byte("capacity")
1631                   ergo_format_byte("occupancy")
1632                   ergo_format_byte_perc("max desired capacity"),
1633                   capacity_after_gc, used_after_gc,
1634                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1635     shrink(shrink_bytes);
1636   }
1637 }
1638 
1639 
1640 HeapWord*
1641 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1642                                            bool* succeeded) {
1643   assert_at_safepoint(true /* should_be_vm_thread */);
1644 
1645   *succeeded = true;
1646   // Let's attempt the allocation first.
1647   HeapWord* result =
1648     attempt_allocation_at_safepoint(word_size,
1649                                  false /* expect_null_mutator_alloc_region */);
1650   if (result != NULL) {
1651     assert(*succeeded, "sanity");
1652     return result;
1653   }
1654 
1655   // In a G1 heap, we're supposed to keep allocation from failing by
1656   // incremental pauses.  Therefore, at least for now, we'll favor
1657   // expansion over collection.  (This might change in the future if we can
1658   // do something smarter than full collection to satisfy a failed alloc.)
1659   result = expand_and_allocate(word_size);
1660   if (result != NULL) {
1661     assert(*succeeded, "sanity");
1662     return result;
1663   }
1664 
1665   // Expansion didn't work, we'll try to do a Full GC.
1666   bool gc_succeeded = do_collection(false, /* explicit_gc */
1667                                     false, /* clear_all_soft_refs */
1668                                     word_size);
1669   if (!gc_succeeded) {
1670     *succeeded = false;
1671     return NULL;
1672   }
1673 
1674   // Retry the allocation
1675   result = attempt_allocation_at_safepoint(word_size,
1676                                   true /* expect_null_mutator_alloc_region */);
1677   if (result != NULL) {
1678     assert(*succeeded, "sanity");
1679     return result;
1680   }
1681 
1682   // Then, try a Full GC that will collect all soft references.
1683   gc_succeeded = do_collection(false, /* explicit_gc */
1684                                true,  /* clear_all_soft_refs */
1685                                word_size);
1686   if (!gc_succeeded) {
1687     *succeeded = false;
1688     return NULL;
1689   }
1690 
1691   // Retry the allocation once more
1692   result = attempt_allocation_at_safepoint(word_size,
1693                                   true /* expect_null_mutator_alloc_region */);
1694   if (result != NULL) {
1695     assert(*succeeded, "sanity");
1696     return result;
1697   }
1698 
1699   assert(!collector_policy()->should_clear_all_soft_refs(),
1700          "Flag should have been handled and cleared prior to this point");
1701 
1702   // What else?  We might try synchronous finalization later.  If the total
1703   // space available is large enough for the allocation, then a more
1704   // complete compaction phase than we've tried so far might be
1705   // appropriate.
1706   assert(*succeeded, "sanity");
1707   return NULL;
1708 }
1709 
1710 // Attempting to expand the heap sufficiently
1711 // to support an allocation of the given "word_size".  If
1712 // successful, perform the allocation and return the address of the
1713 // allocated block, or else "NULL".
1714 
1715 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1716   assert_at_safepoint(true /* should_be_vm_thread */);
1717 
1718   verify_region_sets_optional();
1719 
1720   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1721   ergo_verbose1(ErgoHeapSizing,
1722                 "attempt heap expansion",
1723                 ergo_format_reason("allocation request failed")
1724                 ergo_format_byte("allocation request"),
1725                 word_size * HeapWordSize);
1726   if (expand(expand_bytes)) {
1727     _hrs.verify_optional();
1728     verify_region_sets_optional();
1729     return attempt_allocation_at_safepoint(word_size,
1730                                  false /* expect_null_mutator_alloc_region */);
1731   }
1732   return NULL;
1733 }
1734 
1735 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1736                                              HeapWord* new_end) {
1737   assert(old_end != new_end, "don't call this otherwise");
1738   assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1739 
1740   // Update the committed mem region.
1741   _g1_committed.set_end(new_end);
1742   // Tell the card table about the update.
1743   Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1744   // Tell the BOT about the update.
1745   _bot_shared->resize(_g1_committed.word_size());
1746 }
1747 
1748 bool G1CollectedHeap::expand(size_t expand_bytes) {
1749   size_t old_mem_size = _g1_storage.committed_size();
1750   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1751   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1752                                        HeapRegion::GrainBytes);
1753   ergo_verbose2(ErgoHeapSizing,
1754                 "expand the heap",
1755                 ergo_format_byte("requested expansion amount")
1756                 ergo_format_byte("attempted expansion amount"),
1757                 expand_bytes, aligned_expand_bytes);
1758 
1759   // First commit the memory.
1760   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1761   bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1762   if (successful) {
1763     // Then propagate this update to the necessary data structures.
1764     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1765     update_committed_space(old_end, new_end);
1766 
1767     FreeRegionList expansion_list("Local Expansion List");
1768     MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1769     assert(mr.start() == old_end, "post-condition");
1770     // mr might be a smaller region than what was requested if
1771     // expand_by() was unable to allocate the HeapRegion instances
1772     assert(mr.end() <= new_end, "post-condition");
1773 
1774     size_t actual_expand_bytes = mr.byte_size();
1775     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1776     assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1777            "post-condition");
1778     if (actual_expand_bytes < aligned_expand_bytes) {
1779       // We could not expand _hrs to the desired size. In this case we
1780       // need to shrink the committed space accordingly.
1781       assert(mr.end() < new_end, "invariant");
1782 
1783       size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1784       // First uncommit the memory.
1785       _g1_storage.shrink_by(diff_bytes);
1786       // Then propagate this update to the necessary data structures.
1787       update_committed_space(new_end, mr.end());
1788     }
1789     _free_list.add_as_tail(&expansion_list);
1790 
1791     if (_hr_printer.is_active()) {
1792       HeapWord* curr = mr.start();
1793       while (curr < mr.end()) {
1794         HeapWord* curr_end = curr + HeapRegion::GrainWords;
1795         _hr_printer.commit(curr, curr_end);
1796         curr = curr_end;
1797       }
1798       assert(curr == mr.end(), "post-condition");
1799     }
1800     g1_policy()->record_new_heap_size(n_regions());
1801   } else {
1802     ergo_verbose0(ErgoHeapSizing,
1803                   "did not expand the heap",
1804                   ergo_format_reason("heap expansion operation failed"));
1805     // The expansion of the virtual storage space was unsuccessful.
1806     // Let's see if it was because we ran out of swap.
1807     if (G1ExitOnExpansionFailure &&
1808         _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1809       // We had head room...
1810       vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion");
1811     }
1812   }
1813   return successful;
1814 }
1815 
1816 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1817   size_t old_mem_size = _g1_storage.committed_size();
1818   size_t aligned_shrink_bytes =
1819     ReservedSpace::page_align_size_down(shrink_bytes);
1820   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1821                                          HeapRegion::GrainBytes);
1822   uint num_regions_deleted = 0;
1823   MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted);
1824   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1825   assert(mr.end() == old_end, "post-condition");
1826 
1827   ergo_verbose3(ErgoHeapSizing,
1828                 "shrink the heap",
1829                 ergo_format_byte("requested shrinking amount")
1830                 ergo_format_byte("aligned shrinking amount")
1831                 ergo_format_byte("attempted shrinking amount"),
1832                 shrink_bytes, aligned_shrink_bytes, mr.byte_size());
1833   if (mr.byte_size() > 0) {
1834     if (_hr_printer.is_active()) {
1835       HeapWord* curr = mr.end();
1836       while (curr > mr.start()) {
1837         HeapWord* curr_end = curr;
1838         curr -= HeapRegion::GrainWords;
1839         _hr_printer.uncommit(curr, curr_end);
1840       }
1841       assert(curr == mr.start(), "post-condition");
1842     }
1843 
1844     _g1_storage.shrink_by(mr.byte_size());
1845     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1846     assert(mr.start() == new_end, "post-condition");
1847 
1848     _expansion_regions += num_regions_deleted;
1849     update_committed_space(old_end, new_end);
1850     HeapRegionRemSet::shrink_heap(n_regions());
1851     g1_policy()->record_new_heap_size(n_regions());
1852   } else {
1853     ergo_verbose0(ErgoHeapSizing,
1854                   "did not shrink the heap",
1855                   ergo_format_reason("heap shrinking operation failed"));
1856   }
1857 }
1858 
1859 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1860   verify_region_sets_optional();
1861 
1862   // We should only reach here at the end of a Full GC which means we
1863   // should not not be holding to any GC alloc regions. The method
1864   // below will make sure of that and do any remaining clean up.
1865   abandon_gc_alloc_regions();
1866 
1867   // Instead of tearing down / rebuilding the free lists here, we
1868   // could instead use the remove_all_pending() method on free_list to
1869   // remove only the ones that we need to remove.
1870   tear_down_region_sets(true /* free_list_only */);
1871   shrink_helper(shrink_bytes);
1872   rebuild_region_sets(true /* free_list_only */);
1873 
1874   _hrs.verify_optional();
1875   verify_region_sets_optional();
1876 }
1877 
1878 // Public methods.
1879 
1880 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1881 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1882 #endif // _MSC_VER
1883 
1884 
1885 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1886   SharedHeap(policy_),
1887   _g1_policy(policy_),
1888   _dirty_card_queue_set(false),
1889   _into_cset_dirty_card_queue_set(false),
1890   _is_alive_closure_cm(this),
1891   _is_alive_closure_stw(this),
1892   _ref_processor_cm(NULL),
1893   _ref_processor_stw(NULL),
1894   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1895   _bot_shared(NULL),
1896   _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1897   _evac_failure_scan_stack(NULL) ,
1898   _mark_in_progress(false),
1899   _cg1r(NULL), _summary_bytes_used(0),
1900   _g1mm(NULL),
1901   _refine_cte_cl(NULL),
1902   _full_collection(false),
1903   _free_list("Master Free List"),
1904   _secondary_free_list("Secondary Free List"),
1905   _old_set("Old Set"),
1906   _humongous_set("Master Humongous Set"),
1907   _free_regions_coming(false),
1908   _young_list(new YoungList(this)),
1909   _gc_time_stamp(0),
1910   _retained_old_gc_alloc_region(NULL),
1911   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1912   _old_plab_stats(OldPLABSize, PLABWeight),
1913   _expand_heap_after_alloc_failure(true),
1914   _surviving_young_words(NULL),
1915   _old_marking_cycles_started(0),
1916   _old_marking_cycles_completed(0),
1917   _in_cset_fast_test(NULL),
1918   _in_cset_fast_test_base(NULL),
1919   _dirty_cards_region_list(NULL),
1920   _worker_cset_start_region(NULL),
1921   _worker_cset_start_region_time_stamp(NULL) {
1922   _g1h = this; // To catch bugs.
1923   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1924     vm_exit_during_initialization("Failed necessary allocation.");
1925   }
1926 
1927   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1928 
1929   int n_queues = MAX2((int)ParallelGCThreads, 1);
1930   _task_queues = new RefToScanQueueSet(n_queues);
1931 
1932   int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1933   assert(n_rem_sets > 0, "Invariant.");
1934 
1935   HeapRegionRemSetIterator** iter_arr =
1936     NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues, mtGC);
1937   for (int i = 0; i < n_queues; i++) {
1938     iter_arr[i] = new HeapRegionRemSetIterator();
1939   }
1940   _rem_set_iterator = iter_arr;
1941 
1942   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1943   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1944 
1945   for (int i = 0; i < n_queues; i++) {
1946     RefToScanQueue* q = new RefToScanQueue();
1947     q->initialize();
1948     _task_queues->register_queue(i, q);
1949   }
1950 
1951   clear_cset_start_regions();
1952 
1953   // Initialize the G1EvacuationFailureALot counters and flags.
1954   NOT_PRODUCT(reset_evacuation_should_fail();)
1955 
1956   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1957 }
1958 
1959 jint G1CollectedHeap::initialize() {
1960   CollectedHeap::pre_initialize();
1961   os::enable_vtime();
1962 
1963   G1Log::init();
1964 
1965   // Necessary to satisfy locking discipline assertions.
1966 
1967   MutexLocker x(Heap_lock);
1968 
1969   // We have to initialize the printer before committing the heap, as
1970   // it will be used then.
1971   _hr_printer.set_active(G1PrintHeapRegions);
1972 
1973   // While there are no constraints in the GC code that HeapWordSize
1974   // be any particular value, there are multiple other areas in the
1975   // system which believe this to be true (e.g. oop->object_size in some
1976   // cases incorrectly returns the size in wordSize units rather than
1977   // HeapWordSize).
1978   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1979 
1980   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1981   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1982 
1983   // Ensure that the sizes are properly aligned.
1984   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1985   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1986 
1987   _cg1r = new ConcurrentG1Refine();
1988 
1989   // Reserve the maximum.
1990 
1991   // When compressed oops are enabled, the preferred heap base
1992   // is calculated by subtracting the requested size from the
1993   // 32Gb boundary and using the result as the base address for
1994   // heap reservation. If the requested size is not aligned to
1995   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1996   // into the ReservedHeapSpace constructor) then the actual
1997   // base of the reserved heap may end up differing from the
1998   // address that was requested (i.e. the preferred heap base).
1999   // If this happens then we could end up using a non-optimal
2000   // compressed oops mode.
2001 
2002   // Since max_byte_size is aligned to the size of a heap region (checked
2003   // above).
2004   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2005 
2006   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2007                                                  HeapRegion::GrainBytes);
2008 
2009   // It is important to do this in a way such that concurrent readers can't
2010   // temporarily think somethings in the heap.  (I've actually seen this
2011   // happen in asserts: DLD.)
2012   _reserved.set_word_size(0);
2013   _reserved.set_start((HeapWord*)heap_rs.base());
2014   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2015 
2016   _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2017 
2018   // Create the gen rem set (and barrier set) for the entire reserved region.
2019   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2020   set_barrier_set(rem_set()->bs());
2021   if (barrier_set()->is_a(BarrierSet::ModRef)) {
2022     _mr_bs = (ModRefBarrierSet*)_barrier_set;
2023   } else {
2024     vm_exit_during_initialization("G1 requires a mod ref bs.");
2025     return JNI_ENOMEM;
2026   }
2027 
2028   // Also create a G1 rem set.
2029   if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2030     _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2031   } else {
2032     vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2033     return JNI_ENOMEM;
2034   }
2035 
2036   // Carve out the G1 part of the heap.
2037 
2038   ReservedSpace g1_rs   = heap_rs.first_part(max_byte_size);
2039   _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2040                            g1_rs.size()/HeapWordSize);
2041 
2042   _g1_storage.initialize(g1_rs, 0);
2043   _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2044   _hrs.initialize((HeapWord*) _g1_reserved.start(),
2045                   (HeapWord*) _g1_reserved.end(),
2046                   _expansion_regions);
2047 
2048   // 6843694 - ensure that the maximum region index can fit
2049   // in the remembered set structures.
2050   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2051   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2052 
2053   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2054   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2055   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2056             "too many cards per region");
2057 
2058   HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2059 
2060   _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2061                                              heap_word_size(init_byte_size));
2062 
2063   _g1h = this;
2064 
2065    _in_cset_fast_test_length = max_regions();
2066    _in_cset_fast_test_base =
2067                    NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2068 
2069    // We're biasing _in_cset_fast_test to avoid subtracting the
2070    // beginning of the heap every time we want to index; basically
2071    // it's the same with what we do with the card table.
2072    _in_cset_fast_test = _in_cset_fast_test_base -
2073                ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2074 
2075    // Clear the _cset_fast_test bitmap in anticipation of adding
2076    // regions to the incremental collection set for the first
2077    // evacuation pause.
2078    clear_cset_fast_test();
2079 
2080   // Create the ConcurrentMark data structure and thread.
2081   // (Must do this late, so that "max_regions" is defined.)
2082   _cm = new ConcurrentMark(this, heap_rs);
2083   if (_cm == NULL || !_cm->completed_initialization()) {
2084     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2085     return JNI_ENOMEM;
2086   }
2087   _cmThread = _cm->cmThread();
2088 
2089   // Initialize the from_card cache structure of HeapRegionRemSet.
2090   HeapRegionRemSet::init_heap(max_regions());
2091 
2092   // Now expand into the initial heap size.
2093   if (!expand(init_byte_size)) {
2094     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2095     return JNI_ENOMEM;
2096   }
2097 
2098   // Perform any initialization actions delegated to the policy.
2099   g1_policy()->init();
2100 
2101   _refine_cte_cl =
2102     new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2103                                     g1_rem_set(),
2104                                     concurrent_g1_refine());
2105   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2106 
2107   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2108                                                SATB_Q_FL_lock,
2109                                                G1SATBProcessCompletedThreshold,
2110                                                Shared_SATB_Q_lock);
2111 
2112   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2113                                                 DirtyCardQ_FL_lock,
2114                                                 concurrent_g1_refine()->yellow_zone(),
2115                                                 concurrent_g1_refine()->red_zone(),
2116                                                 Shared_DirtyCardQ_lock);
2117 
2118   if (G1DeferredRSUpdate) {
2119     dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2120                                       DirtyCardQ_FL_lock,
2121                                       -1, // never trigger processing
2122                                       -1, // no limit on length
2123                                       Shared_DirtyCardQ_lock,
2124                                       &JavaThread::dirty_card_queue_set());
2125   }
2126 
2127   // Initialize the card queue set used to hold cards containing
2128   // references into the collection set.
2129   _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2130                                              DirtyCardQ_FL_lock,
2131                                              -1, // never trigger processing
2132                                              -1, // no limit on length
2133                                              Shared_DirtyCardQ_lock,
2134                                              &JavaThread::dirty_card_queue_set());
2135 
2136   // In case we're keeping closure specialization stats, initialize those
2137   // counts and that mechanism.
2138   SpecializationStats::clear();
2139 
2140   // Do later initialization work for concurrent refinement.
2141   _cg1r->init();
2142 
2143   // Here we allocate the dummy full region that is required by the
2144   // G1AllocRegion class. If we don't pass an address in the reserved
2145   // space here, lots of asserts fire.
2146 
2147   HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2148                                              _g1_reserved.start());
2149   // We'll re-use the same region whether the alloc region will
2150   // require BOT updates or not and, if it doesn't, then a non-young
2151   // region will complain that it cannot support allocations without
2152   // BOT updates. So we'll tag the dummy region as young to avoid that.
2153   dummy_region->set_young();
2154   // Make sure it's full.
2155   dummy_region->set_top(dummy_region->end());
2156   G1AllocRegion::setup(this, dummy_region);
2157 
2158   init_mutator_alloc_region();
2159 
2160   // Do create of the monitoring and management support so that
2161   // values in the heap have been properly initialized.
2162   _g1mm = new G1MonitoringSupport(this);
2163 
2164   return JNI_OK;
2165 }
2166 
2167 void G1CollectedHeap::ref_processing_init() {
2168   // Reference processing in G1 currently works as follows:
2169   //
2170   // * There are two reference processor instances. One is
2171   //   used to record and process discovered references
2172   //   during concurrent marking; the other is used to
2173   //   record and process references during STW pauses
2174   //   (both full and incremental).
2175   // * Both ref processors need to 'span' the entire heap as
2176   //   the regions in the collection set may be dotted around.
2177   //
2178   // * For the concurrent marking ref processor:
2179   //   * Reference discovery is enabled at initial marking.
2180   //   * Reference discovery is disabled and the discovered
2181   //     references processed etc during remarking.
2182   //   * Reference discovery is MT (see below).
2183   //   * Reference discovery requires a barrier (see below).
2184   //   * Reference processing may or may not be MT
2185   //     (depending on the value of ParallelRefProcEnabled
2186   //     and ParallelGCThreads).
2187   //   * A full GC disables reference discovery by the CM
2188   //     ref processor and abandons any entries on it's
2189   //     discovered lists.
2190   //
2191   // * For the STW processor:
2192   //   * Non MT discovery is enabled at the start of a full GC.
2193   //   * Processing and enqueueing during a full GC is non-MT.
2194   //   * During a full GC, references are processed after marking.
2195   //
2196   //   * Discovery (may or may not be MT) is enabled at the start
2197   //     of an incremental evacuation pause.
2198   //   * References are processed near the end of a STW evacuation pause.
2199   //   * For both types of GC:
2200   //     * Discovery is atomic - i.e. not concurrent.
2201   //     * Reference discovery will not need a barrier.
2202 
2203   SharedHeap::ref_processing_init();
2204   MemRegion mr = reserved_region();
2205 
2206   // Concurrent Mark ref processor
2207   _ref_processor_cm =
2208     new ReferenceProcessor(mr,    // span
2209                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2210                                 // mt processing
2211                            (int) ParallelGCThreads,
2212                                 // degree of mt processing
2213                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2214                                 // mt discovery
2215                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2216                                 // degree of mt discovery
2217                            false,
2218                                 // Reference discovery is not atomic
2219                            &_is_alive_closure_cm,
2220                                 // is alive closure
2221                                 // (for efficiency/performance)
2222                            true);
2223                                 // Setting next fields of discovered
2224                                 // lists requires a barrier.
2225 
2226   // STW ref processor
2227   _ref_processor_stw =
2228     new ReferenceProcessor(mr,    // span
2229                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2230                                 // mt processing
2231                            MAX2((int)ParallelGCThreads, 1),
2232                                 // degree of mt processing
2233                            (ParallelGCThreads > 1),
2234                                 // mt discovery
2235                            MAX2((int)ParallelGCThreads, 1),
2236                                 // degree of mt discovery
2237                            true,
2238                                 // Reference discovery is atomic
2239                            &_is_alive_closure_stw,
2240                                 // is alive closure
2241                                 // (for efficiency/performance)
2242                            false);
2243                                 // Setting next fields of discovered
2244                                 // lists requires a barrier.
2245 }
2246 
2247 size_t G1CollectedHeap::capacity() const {
2248   return _g1_committed.byte_size();
2249 }
2250 
2251 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2252   assert(!hr->continuesHumongous(), "pre-condition");
2253   hr->reset_gc_time_stamp();
2254   if (hr->startsHumongous()) {
2255     uint first_index = hr->hrs_index() + 1;
2256     uint last_index = hr->last_hc_index();
2257     for (uint i = first_index; i < last_index; i += 1) {
2258       HeapRegion* chr = region_at(i);
2259       assert(chr->continuesHumongous(), "sanity");
2260       chr->reset_gc_time_stamp();
2261     }
2262   }
2263 }
2264 
2265 #ifndef PRODUCT
2266 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2267 private:
2268   unsigned _gc_time_stamp;
2269   bool _failures;
2270 
2271 public:
2272   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2273     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2274 
2275   virtual bool doHeapRegion(HeapRegion* hr) {
2276     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2277     if (_gc_time_stamp != region_gc_time_stamp) {
2278       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2279                              "expected %d", HR_FORMAT_PARAMS(hr),
2280                              region_gc_time_stamp, _gc_time_stamp);
2281       _failures = true;
2282     }
2283     return false;
2284   }
2285 
2286   bool failures() { return _failures; }
2287 };
2288 
2289 void G1CollectedHeap::check_gc_time_stamps() {
2290   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2291   heap_region_iterate(&cl);
2292   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2293 }
2294 #endif // PRODUCT
2295 
2296 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2297                                                  DirtyCardQueue* into_cset_dcq,
2298                                                  bool concurrent,
2299                                                  int worker_i) {
2300   // Clean cards in the hot card cache
2301   concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
2302 
2303   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2304   int n_completed_buffers = 0;
2305   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2306     n_completed_buffers++;
2307   }
2308   g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2309   dcqs.clear_n_completed_buffers();
2310   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2311 }
2312 
2313 
2314 // Computes the sum of the storage used by the various regions.
2315 
2316 size_t G1CollectedHeap::used() const {
2317   assert(Heap_lock->owner() != NULL,
2318          "Should be owned on this thread's behalf.");
2319   size_t result = _summary_bytes_used;
2320   // Read only once in case it is set to NULL concurrently
2321   HeapRegion* hr = _mutator_alloc_region.get();
2322   if (hr != NULL)
2323     result += hr->used();
2324   return result;
2325 }
2326 
2327 size_t G1CollectedHeap::used_unlocked() const {
2328   size_t result = _summary_bytes_used;
2329   return result;
2330 }
2331 
2332 class SumUsedClosure: public HeapRegionClosure {
2333   size_t _used;
2334 public:
2335   SumUsedClosure() : _used(0) {}
2336   bool doHeapRegion(HeapRegion* r) {
2337     if (!r->continuesHumongous()) {
2338       _used += r->used();
2339     }
2340     return false;
2341   }
2342   size_t result() { return _used; }
2343 };
2344 
2345 size_t G1CollectedHeap::recalculate_used() const {
2346   SumUsedClosure blk;
2347   heap_region_iterate(&blk);
2348   return blk.result();
2349 }
2350 
2351 size_t G1CollectedHeap::unsafe_max_alloc() {
2352   if (free_regions() > 0) return HeapRegion::GrainBytes;
2353   // otherwise, is there space in the current allocation region?
2354 
2355   // We need to store the current allocation region in a local variable
2356   // here. The problem is that this method doesn't take any locks and
2357   // there may be other threads which overwrite the current allocation
2358   // region field. attempt_allocation(), for example, sets it to NULL
2359   // and this can happen *after* the NULL check here but before the call
2360   // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2361   // to be a problem in the optimized build, since the two loads of the
2362   // current allocation region field are optimized away.
2363   HeapRegion* hr = _mutator_alloc_region.get();
2364   if (hr == NULL) {
2365     return 0;
2366   }
2367   return hr->free();
2368 }
2369 
2370 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2371   switch (cause) {
2372     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2373     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2374     case GCCause::_g1_humongous_allocation: return true;
2375     default:                                return false;
2376   }
2377 }
2378 
2379 #ifndef PRODUCT
2380 void G1CollectedHeap::allocate_dummy_regions() {
2381   // Let's fill up most of the region
2382   size_t word_size = HeapRegion::GrainWords - 1024;
2383   // And as a result the region we'll allocate will be humongous.
2384   guarantee(isHumongous(word_size), "sanity");
2385 
2386   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2387     // Let's use the existing mechanism for the allocation
2388     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2389     if (dummy_obj != NULL) {
2390       MemRegion mr(dummy_obj, word_size);
2391       CollectedHeap::fill_with_object(mr);
2392     } else {
2393       // If we can't allocate once, we probably cannot allocate
2394       // again. Let's get out of the loop.
2395       break;
2396     }
2397   }
2398 }
2399 #endif // !PRODUCT
2400 
2401 void G1CollectedHeap::increment_old_marking_cycles_started() {
2402   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2403     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2404     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2405     _old_marking_cycles_started, _old_marking_cycles_completed));
2406 
2407   _old_marking_cycles_started++;
2408 }
2409 
2410 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2411   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2412 
2413   // We assume that if concurrent == true, then the caller is a
2414   // concurrent thread that was joined the Suspendible Thread
2415   // Set. If there's ever a cheap way to check this, we should add an
2416   // assert here.
2417 
2418   // Given that this method is called at the end of a Full GC or of a
2419   // concurrent cycle, and those can be nested (i.e., a Full GC can
2420   // interrupt a concurrent cycle), the number of full collections
2421   // completed should be either one (in the case where there was no
2422   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2423   // behind the number of full collections started.
2424 
2425   // This is the case for the inner caller, i.e. a Full GC.
2426   assert(concurrent ||
2427          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2428          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2429          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2430                  "is inconsistent with _old_marking_cycles_completed = %u",
2431                  _old_marking_cycles_started, _old_marking_cycles_completed));
2432 
2433   // This is the case for the outer caller, i.e. the concurrent cycle.
2434   assert(!concurrent ||
2435          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2436          err_msg("for outer caller (concurrent cycle): "
2437                  "_old_marking_cycles_started = %u "
2438                  "is inconsistent with _old_marking_cycles_completed = %u",
2439                  _old_marking_cycles_started, _old_marking_cycles_completed));
2440 
2441   _old_marking_cycles_completed += 1;
2442 
2443   // We need to clear the "in_progress" flag in the CM thread before
2444   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2445   // is set) so that if a waiter requests another System.gc() it doesn't
2446   // incorrectly see that a marking cyle is still in progress.
2447   if (concurrent) {
2448     _cmThread->clear_in_progress();
2449   }
2450 
2451   // This notify_all() will ensure that a thread that called
2452   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2453   // and it's waiting for a full GC to finish will be woken up. It is
2454   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2455   FullGCCount_lock->notify_all();
2456 }
2457 
2458 void G1CollectedHeap::collect(GCCause::Cause cause) {
2459   assert_heap_not_locked();
2460 
2461   unsigned int gc_count_before;
2462   unsigned int old_marking_count_before;
2463   bool retry_gc;
2464 
2465   do {
2466     retry_gc = false;
2467 
2468     {
2469       MutexLocker ml(Heap_lock);
2470 
2471       // Read the GC count while holding the Heap_lock
2472       gc_count_before = total_collections();
2473       old_marking_count_before = _old_marking_cycles_started;
2474     }
2475 
2476     if (should_do_concurrent_full_gc(cause)) {
2477       // Schedule an initial-mark evacuation pause that will start a
2478       // concurrent cycle. We're setting word_size to 0 which means that
2479       // we are not requesting a post-GC allocation.
2480       VM_G1IncCollectionPause op(gc_count_before,
2481                                  0,     /* word_size */
2482                                  true,  /* should_initiate_conc_mark */
2483                                  g1_policy()->max_pause_time_ms(),
2484                                  cause);
2485 
2486       VMThread::execute(&op);
2487       if (!op.pause_succeeded()) {
2488         if (old_marking_count_before == _old_marking_cycles_started) {
2489           retry_gc = op.should_retry_gc();
2490         } else {
2491           // A Full GC happened while we were trying to schedule the
2492           // initial-mark GC. No point in starting a new cycle given
2493           // that the whole heap was collected anyway.
2494         }
2495 
2496         if (retry_gc) {
2497           if (GC_locker::is_active_and_needs_gc()) {
2498             GC_locker::stall_until_clear();
2499           }
2500         }
2501       }
2502     } else {
2503       if (cause == GCCause::_gc_locker
2504           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2505 
2506         // Schedule a standard evacuation pause. We're setting word_size
2507         // to 0 which means that we are not requesting a post-GC allocation.
2508         VM_G1IncCollectionPause op(gc_count_before,
2509                                    0,     /* word_size */
2510                                    false, /* should_initiate_conc_mark */
2511                                    g1_policy()->max_pause_time_ms(),
2512                                    cause);
2513         VMThread::execute(&op);
2514       } else {
2515         // Schedule a Full GC.
2516         VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2517         VMThread::execute(&op);
2518       }
2519     }
2520   } while (retry_gc);
2521 }
2522 
2523 bool G1CollectedHeap::is_in(const void* p) const {
2524   if (_g1_committed.contains(p)) {
2525     // Given that we know that p is in the committed space,
2526     // heap_region_containing_raw() should successfully
2527     // return the containing region.
2528     HeapRegion* hr = heap_region_containing_raw(p);
2529     return hr->is_in(p);
2530   } else {
2531     return false;
2532   }
2533 }
2534 
2535 // Iteration functions.
2536 
2537 // Iterates an OopClosure over all ref-containing fields of objects
2538 // within a HeapRegion.
2539 
2540 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2541   MemRegion _mr;
2542   ExtendedOopClosure* _cl;
2543 public:
2544   IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2545     : _mr(mr), _cl(cl) {}
2546   bool doHeapRegion(HeapRegion* r) {
2547     if (!r->continuesHumongous()) {
2548       r->oop_iterate(_cl);
2549     }
2550     return false;
2551   }
2552 };
2553 
2554 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2555   IterateOopClosureRegionClosure blk(_g1_committed, cl);
2556   heap_region_iterate(&blk);
2557 }
2558 
2559 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2560   IterateOopClosureRegionClosure blk(mr, cl);
2561   heap_region_iterate(&blk);
2562 }
2563 
2564 // Iterates an ObjectClosure over all objects within a HeapRegion.
2565 
2566 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2567   ObjectClosure* _cl;
2568 public:
2569   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2570   bool doHeapRegion(HeapRegion* r) {
2571     if (! r->continuesHumongous()) {
2572       r->object_iterate(_cl);
2573     }
2574     return false;
2575   }
2576 };
2577 
2578 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2579   IterateObjectClosureRegionClosure blk(cl);
2580   heap_region_iterate(&blk);
2581 }
2582 
2583 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2584   // FIXME: is this right?
2585   guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2586 }
2587 
2588 // Calls a SpaceClosure on a HeapRegion.
2589 
2590 class SpaceClosureRegionClosure: public HeapRegionClosure {
2591   SpaceClosure* _cl;
2592 public:
2593   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2594   bool doHeapRegion(HeapRegion* r) {
2595     _cl->do_space(r);
2596     return false;
2597   }
2598 };
2599 
2600 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2601   SpaceClosureRegionClosure blk(cl);
2602   heap_region_iterate(&blk);
2603 }
2604 
2605 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2606   _hrs.iterate(cl);
2607 }
2608 
2609 void
2610 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2611                                                  uint worker_id,
2612                                                  uint no_of_par_workers,
2613                                                  jint claim_value) {
2614   const uint regions = n_regions();
2615   const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2616                              no_of_par_workers :
2617                              1);
2618   assert(UseDynamicNumberOfGCThreads ||
2619          no_of_par_workers == workers()->total_workers(),
2620          "Non dynamic should use fixed number of workers");
2621   // try to spread out the starting points of the workers
2622   const HeapRegion* start_hr =
2623                         start_region_for_worker(worker_id, no_of_par_workers);
2624   const uint start_index = start_hr->hrs_index();
2625 
2626   // each worker will actually look at all regions
2627   for (uint count = 0; count < regions; ++count) {
2628     const uint index = (start_index + count) % regions;
2629     assert(0 <= index && index < regions, "sanity");
2630     HeapRegion* r = region_at(index);
2631     // we'll ignore "continues humongous" regions (we'll process them
2632     // when we come across their corresponding "start humongous"
2633     // region) and regions already claimed
2634     if (r->claim_value() == claim_value || r->continuesHumongous()) {
2635       continue;
2636     }
2637     // OK, try to claim it
2638     if (r->claimHeapRegion(claim_value)) {
2639       // success!
2640       assert(!r->continuesHumongous(), "sanity");
2641       if (r->startsHumongous()) {
2642         // If the region is "starts humongous" we'll iterate over its
2643         // "continues humongous" first; in fact we'll do them
2644         // first. The order is important. In on case, calling the
2645         // closure on the "starts humongous" region might de-allocate
2646         // and clear all its "continues humongous" regions and, as a
2647         // result, we might end up processing them twice. So, we'll do
2648         // them first (notice: most closures will ignore them anyway) and
2649         // then we'll do the "starts humongous" region.
2650         for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2651           HeapRegion* chr = region_at(ch_index);
2652 
2653           // if the region has already been claimed or it's not
2654           // "continues humongous" we're done
2655           if (chr->claim_value() == claim_value ||
2656               !chr->continuesHumongous()) {
2657             break;
2658           }
2659 
2660           // Noone should have claimed it directly. We can given
2661           // that we claimed its "starts humongous" region.
2662           assert(chr->claim_value() != claim_value, "sanity");
2663           assert(chr->humongous_start_region() == r, "sanity");
2664 
2665           if (chr->claimHeapRegion(claim_value)) {
2666             // we should always be able to claim it; noone else should
2667             // be trying to claim this region
2668 
2669             bool res2 = cl->doHeapRegion(chr);
2670             assert(!res2, "Should not abort");
2671 
2672             // Right now, this holds (i.e., no closure that actually
2673             // does something with "continues humongous" regions
2674             // clears them). We might have to weaken it in the future,
2675             // but let's leave these two asserts here for extra safety.
2676             assert(chr->continuesHumongous(), "should still be the case");
2677             assert(chr->humongous_start_region() == r, "sanity");
2678           } else {
2679             guarantee(false, "we should not reach here");
2680           }
2681         }
2682       }
2683 
2684       assert(!r->continuesHumongous(), "sanity");
2685       bool res = cl->doHeapRegion(r);
2686       assert(!res, "Should not abort");
2687     }
2688   }
2689 }
2690 
2691 class ResetClaimValuesClosure: public HeapRegionClosure {
2692 public:
2693   bool doHeapRegion(HeapRegion* r) {
2694     r->set_claim_value(HeapRegion::InitialClaimValue);
2695     return false;
2696   }
2697 };
2698 
2699 void G1CollectedHeap::reset_heap_region_claim_values() {
2700   ResetClaimValuesClosure blk;
2701   heap_region_iterate(&blk);
2702 }
2703 
2704 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2705   ResetClaimValuesClosure blk;
2706   collection_set_iterate(&blk);
2707 }
2708 
2709 #ifdef ASSERT
2710 // This checks whether all regions in the heap have the correct claim
2711 // value. I also piggy-backed on this a check to ensure that the
2712 // humongous_start_region() information on "continues humongous"
2713 // regions is correct.
2714 
2715 class CheckClaimValuesClosure : public HeapRegionClosure {
2716 private:
2717   jint _claim_value;
2718   uint _failures;
2719   HeapRegion* _sh_region;
2720 
2721 public:
2722   CheckClaimValuesClosure(jint claim_value) :
2723     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2724   bool doHeapRegion(HeapRegion* r) {
2725     if (r->claim_value() != _claim_value) {
2726       gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2727                              "claim value = %d, should be %d",
2728                              HR_FORMAT_PARAMS(r),
2729                              r->claim_value(), _claim_value);
2730       ++_failures;
2731     }
2732     if (!r->isHumongous()) {
2733       _sh_region = NULL;
2734     } else if (r->startsHumongous()) {
2735       _sh_region = r;
2736     } else if (r->continuesHumongous()) {
2737       if (r->humongous_start_region() != _sh_region) {
2738         gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2739                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2740                                HR_FORMAT_PARAMS(r),
2741                                r->humongous_start_region(),
2742                                _sh_region);
2743         ++_failures;
2744       }
2745     }
2746     return false;
2747   }
2748   uint failures() { return _failures; }
2749 };
2750 
2751 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2752   CheckClaimValuesClosure cl(claim_value);
2753   heap_region_iterate(&cl);
2754   return cl.failures() == 0;
2755 }
2756 
2757 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2758 private:
2759   jint _claim_value;
2760   uint _failures;
2761 
2762 public:
2763   CheckClaimValuesInCSetHRClosure(jint claim_value) :
2764     _claim_value(claim_value), _failures(0) { }
2765 
2766   uint failures() { return _failures; }
2767 
2768   bool doHeapRegion(HeapRegion* hr) {
2769     assert(hr->in_collection_set(), "how?");
2770     assert(!hr->isHumongous(), "H-region in CSet");
2771     if (hr->claim_value() != _claim_value) {
2772       gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2773                              "claim value = %d, should be %d",
2774                              HR_FORMAT_PARAMS(hr),
2775                              hr->claim_value(), _claim_value);
2776       _failures += 1;
2777     }
2778     return false;
2779   }
2780 };
2781 
2782 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2783   CheckClaimValuesInCSetHRClosure cl(claim_value);
2784   collection_set_iterate(&cl);
2785   return cl.failures() == 0;
2786 }
2787 #endif // ASSERT
2788 
2789 // Clear the cached CSet starting regions and (more importantly)
2790 // the time stamps. Called when we reset the GC time stamp.
2791 void G1CollectedHeap::clear_cset_start_regions() {
2792   assert(_worker_cset_start_region != NULL, "sanity");
2793   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2794 
2795   int n_queues = MAX2((int)ParallelGCThreads, 1);
2796   for (int i = 0; i < n_queues; i++) {
2797     _worker_cset_start_region[i] = NULL;
2798     _worker_cset_start_region_time_stamp[i] = 0;
2799   }
2800 }
2801 
2802 // Given the id of a worker, obtain or calculate a suitable
2803 // starting region for iterating over the current collection set.
2804 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2805   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2806 
2807   HeapRegion* result = NULL;
2808   unsigned gc_time_stamp = get_gc_time_stamp();
2809 
2810   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2811     // Cached starting region for current worker was set
2812     // during the current pause - so it's valid.
2813     // Note: the cached starting heap region may be NULL
2814     // (when the collection set is empty).
2815     result = _worker_cset_start_region[worker_i];
2816     assert(result == NULL || result->in_collection_set(), "sanity");
2817     return result;
2818   }
2819 
2820   // The cached entry was not valid so let's calculate
2821   // a suitable starting heap region for this worker.
2822 
2823   // We want the parallel threads to start their collection
2824   // set iteration at different collection set regions to
2825   // avoid contention.
2826   // If we have:
2827   //          n collection set regions
2828   //          p threads
2829   // Then thread t will start at region floor ((t * n) / p)
2830 
2831   result = g1_policy()->collection_set();
2832   if (G1CollectedHeap::use_parallel_gc_threads()) {
2833     uint cs_size = g1_policy()->cset_region_length();
2834     uint active_workers = workers()->active_workers();
2835     assert(UseDynamicNumberOfGCThreads ||
2836              active_workers == workers()->total_workers(),
2837              "Unless dynamic should use total workers");
2838 
2839     uint end_ind   = (cs_size * worker_i) / active_workers;
2840     uint start_ind = 0;
2841 
2842     if (worker_i > 0 &&
2843         _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2844       // Previous workers starting region is valid
2845       // so let's iterate from there
2846       start_ind = (cs_size * (worker_i - 1)) / active_workers;
2847       result = _worker_cset_start_region[worker_i - 1];
2848     }
2849 
2850     for (uint i = start_ind; i < end_ind; i++) {
2851       result = result->next_in_collection_set();
2852     }
2853   }
2854 
2855   // Note: the calculated starting heap region may be NULL
2856   // (when the collection set is empty).
2857   assert(result == NULL || result->in_collection_set(), "sanity");
2858   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2859          "should be updated only once per pause");
2860   _worker_cset_start_region[worker_i] = result;
2861   OrderAccess::storestore();
2862   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2863   return result;
2864 }
2865 
2866 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2867                                                      uint no_of_par_workers) {
2868   uint worker_num =
2869            G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2870   assert(UseDynamicNumberOfGCThreads ||
2871          no_of_par_workers == workers()->total_workers(),
2872          "Non dynamic should use fixed number of workers");
2873   const uint start_index = n_regions() * worker_i / worker_num;
2874   return region_at(start_index);
2875 }
2876 
2877 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2878   HeapRegion* r = g1_policy()->collection_set();
2879   while (r != NULL) {
2880     HeapRegion* next = r->next_in_collection_set();
2881     if (cl->doHeapRegion(r)) {
2882       cl->incomplete();
2883       return;
2884     }
2885     r = next;
2886   }
2887 }
2888 
2889 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2890                                                   HeapRegionClosure *cl) {
2891   if (r == NULL) {
2892     // The CSet is empty so there's nothing to do.
2893     return;
2894   }
2895 
2896   assert(r->in_collection_set(),
2897          "Start region must be a member of the collection set.");
2898   HeapRegion* cur = r;
2899   while (cur != NULL) {
2900     HeapRegion* next = cur->next_in_collection_set();
2901     if (cl->doHeapRegion(cur) && false) {
2902       cl->incomplete();
2903       return;
2904     }
2905     cur = next;
2906   }
2907   cur = g1_policy()->collection_set();
2908   while (cur != r) {
2909     HeapRegion* next = cur->next_in_collection_set();
2910     if (cl->doHeapRegion(cur) && false) {
2911       cl->incomplete();
2912       return;
2913     }
2914     cur = next;
2915   }
2916 }
2917 
2918 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2919   return n_regions() > 0 ? region_at(0) : NULL;
2920 }
2921 
2922 
2923 Space* G1CollectedHeap::space_containing(const void* addr) const {
2924   Space* res = heap_region_containing(addr);
2925   return res;
2926 }
2927 
2928 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2929   Space* sp = space_containing(addr);
2930   if (sp != NULL) {
2931     return sp->block_start(addr);
2932   }
2933   return NULL;
2934 }
2935 
2936 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2937   Space* sp = space_containing(addr);
2938   assert(sp != NULL, "block_size of address outside of heap");
2939   return sp->block_size(addr);
2940 }
2941 
2942 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2943   Space* sp = space_containing(addr);
2944   return sp->block_is_obj(addr);
2945 }
2946 
2947 bool G1CollectedHeap::supports_tlab_allocation() const {
2948   return true;
2949 }
2950 
2951 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2952   return HeapRegion::GrainBytes;
2953 }
2954 
2955 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2956   // Return the remaining space in the cur alloc region, but not less than
2957   // the min TLAB size.
2958 
2959   // Also, this value can be at most the humongous object threshold,
2960   // since we can't allow tlabs to grow big enough to accomodate
2961   // humongous objects.
2962 
2963   HeapRegion* hr = _mutator_alloc_region.get();
2964   size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2965   if (hr == NULL) {
2966     return max_tlab_size;
2967   } else {
2968     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
2969   }
2970 }
2971 
2972 size_t G1CollectedHeap::max_capacity() const {
2973   return _g1_reserved.byte_size();
2974 }
2975 
2976 jlong G1CollectedHeap::millis_since_last_gc() {
2977   // assert(false, "NYI");
2978   return 0;
2979 }
2980 
2981 void G1CollectedHeap::prepare_for_verify() {
2982   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2983     ensure_parsability(false);
2984   }
2985   g1_rem_set()->prepare_for_verify();
2986 }
2987 
2988 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2989                                               VerifyOption vo) {
2990   switch (vo) {
2991   case VerifyOption_G1UsePrevMarking:
2992     return hr->obj_allocated_since_prev_marking(obj);
2993   case VerifyOption_G1UseNextMarking:
2994     return hr->obj_allocated_since_next_marking(obj);
2995   case VerifyOption_G1UseMarkWord:
2996     return false;
2997   default:
2998     ShouldNotReachHere();
2999   }
3000   return false; // keep some compilers happy
3001 }
3002 
3003 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3004   switch (vo) {
3005   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3006   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3007   case VerifyOption_G1UseMarkWord:    return NULL;
3008   default:                            ShouldNotReachHere();
3009   }
3010   return NULL; // keep some compilers happy
3011 }
3012 
3013 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3014   switch (vo) {
3015   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3016   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3017   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
3018   default:                            ShouldNotReachHere();
3019   }
3020   return false; // keep some compilers happy
3021 }
3022 
3023 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3024   switch (vo) {
3025   case VerifyOption_G1UsePrevMarking: return "PTAMS";
3026   case VerifyOption_G1UseNextMarking: return "NTAMS";
3027   case VerifyOption_G1UseMarkWord:    return "NONE";
3028   default:                            ShouldNotReachHere();
3029   }
3030   return NULL; // keep some compilers happy
3031 }
3032 
3033 class VerifyLivenessOopClosure: public OopClosure {
3034   G1CollectedHeap* _g1h;
3035   VerifyOption _vo;
3036 public:
3037   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3038     _g1h(g1h), _vo(vo)
3039   { }
3040   void do_oop(narrowOop *p) { do_oop_work(p); }
3041   void do_oop(      oop *p) { do_oop_work(p); }
3042 
3043   template <class T> void do_oop_work(T *p) {
3044     oop obj = oopDesc::load_decode_heap_oop(p);
3045     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3046               "Dead object referenced by a not dead object");
3047   }
3048 };
3049 
3050 class VerifyObjsInRegionClosure: public ObjectClosure {
3051 private:
3052   G1CollectedHeap* _g1h;
3053   size_t _live_bytes;
3054   HeapRegion *_hr;
3055   VerifyOption _vo;
3056 public:
3057   // _vo == UsePrevMarking -> use "prev" marking information,
3058   // _vo == UseNextMarking -> use "next" marking information,
3059   // _vo == UseMarkWord    -> use mark word from object header.
3060   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3061     : _live_bytes(0), _hr(hr), _vo(vo) {
3062     _g1h = G1CollectedHeap::heap();
3063   }
3064   void do_object(oop o) {
3065     VerifyLivenessOopClosure isLive(_g1h, _vo);
3066     assert(o != NULL, "Huh?");
3067     if (!_g1h->is_obj_dead_cond(o, _vo)) {
3068       // If the object is alive according to the mark word,
3069       // then verify that the marking information agrees.
3070       // Note we can't verify the contra-positive of the
3071       // above: if the object is dead (according to the mark
3072       // word), it may not be marked, or may have been marked
3073       // but has since became dead, or may have been allocated
3074       // since the last marking.
3075       if (_vo == VerifyOption_G1UseMarkWord) {
3076         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3077       }
3078 
3079       o->oop_iterate_no_header(&isLive);
3080       if (!_hr->obj_allocated_since_prev_marking(o)) {
3081         size_t obj_size = o->size();    // Make sure we don't overflow
3082         _live_bytes += (obj_size * HeapWordSize);
3083       }
3084     }
3085   }
3086   size_t live_bytes() { return _live_bytes; }
3087 };
3088 
3089 class PrintObjsInRegionClosure : public ObjectClosure {
3090   HeapRegion *_hr;
3091   G1CollectedHeap *_g1;
3092 public:
3093   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3094     _g1 = G1CollectedHeap::heap();
3095   };
3096 
3097   void do_object(oop o) {
3098     if (o != NULL) {
3099       HeapWord *start = (HeapWord *) o;
3100       size_t word_sz = o->size();
3101       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3102                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3103                           (void*) o, word_sz,
3104                           _g1->isMarkedPrev(o),
3105                           _g1->isMarkedNext(o),
3106                           _hr->obj_allocated_since_prev_marking(o));
3107       HeapWord *end = start + word_sz;
3108       HeapWord *cur;
3109       int *val;
3110       for (cur = start; cur < end; cur++) {
3111         val = (int *) cur;
3112         gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3113       }
3114     }
3115   }
3116 };
3117 
3118 class VerifyRegionClosure: public HeapRegionClosure {
3119 private:
3120   bool             _par;
3121   VerifyOption     _vo;
3122   bool             _failures;
3123 public:
3124   // _vo == UsePrevMarking -> use "prev" marking information,
3125   // _vo == UseNextMarking -> use "next" marking information,
3126   // _vo == UseMarkWord    -> use mark word from object header.
3127   VerifyRegionClosure(bool par, VerifyOption vo)
3128     : _par(par),
3129       _vo(vo),
3130       _failures(false) {}
3131 
3132   bool failures() {
3133     return _failures;
3134   }
3135 
3136   bool doHeapRegion(HeapRegion* r) {
3137     if (!r->continuesHumongous()) {
3138       bool failures = false;
3139       r->verify(_vo, &failures);
3140       if (failures) {
3141         _failures = true;
3142       } else {
3143         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3144         r->object_iterate(&not_dead_yet_cl);
3145         if (_vo != VerifyOption_G1UseNextMarking) {
3146           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3147             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3148                                    "max_live_bytes "SIZE_FORMAT" "
3149                                    "< calculated "SIZE_FORMAT,
3150                                    r->bottom(), r->end(),
3151                                    r->max_live_bytes(),
3152                                  not_dead_yet_cl.live_bytes());
3153             _failures = true;
3154           }
3155         } else {
3156           // When vo == UseNextMarking we cannot currently do a sanity
3157           // check on the live bytes as the calculation has not been
3158           // finalized yet.
3159         }
3160       }
3161     }
3162     return false; // stop the region iteration if we hit a failure
3163   }
3164 };
3165 
3166 class YoungRefCounterClosure : public OopClosure {
3167   G1CollectedHeap* _g1h;
3168   int              _count;
3169  public:
3170   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3171   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
3172   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3173 
3174   int count() { return _count; }
3175   void reset_count() { _count = 0; };
3176 };
3177 
3178 class VerifyKlassClosure: public KlassClosure {
3179   YoungRefCounterClosure _young_ref_counter_closure;
3180   OopClosure *_oop_closure;
3181  public:
3182   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3183   void do_klass(Klass* k) {
3184     k->oops_do(_oop_closure);
3185 
3186     _young_ref_counter_closure.reset_count();
3187     k->oops_do(&_young_ref_counter_closure);
3188     if (_young_ref_counter_closure.count() > 0) {
3189       guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3190     }
3191   }
3192 };
3193 
3194 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3195 //       pass it as the perm_blk to SharedHeap::process_strong_roots.
3196 //       When process_strong_roots stop calling perm_blk->younger_refs_iterate
3197 //       we can change this closure to extend the simpler OopClosure.
3198 class VerifyRootsClosure: public OopsInGenClosure {
3199 private:
3200   G1CollectedHeap* _g1h;
3201   VerifyOption     _vo;
3202   bool             _failures;
3203 public:
3204   // _vo == UsePrevMarking -> use "prev" marking information,
3205   // _vo == UseNextMarking -> use "next" marking information,
3206   // _vo == UseMarkWord    -> use mark word from object header.
3207   VerifyRootsClosure(VerifyOption vo) :
3208     _g1h(G1CollectedHeap::heap()),
3209     _vo(vo),
3210     _failures(false) { }
3211 
3212   bool failures() { return _failures; }
3213 
3214   template <class T> void do_oop_nv(T* p) {
3215     T heap_oop = oopDesc::load_heap_oop(p);
3216     if (!oopDesc::is_null(heap_oop)) {
3217       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3218       if (_g1h->is_obj_dead_cond(obj, _vo)) {
3219         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3220                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
3221         if (_vo == VerifyOption_G1UseMarkWord) {
3222           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3223         }
3224         obj->print_on(gclog_or_tty);
3225         _failures = true;
3226       }
3227     }
3228   }
3229 
3230   void do_oop(oop* p)       { do_oop_nv(p); }
3231   void do_oop(narrowOop* p) { do_oop_nv(p); }
3232 };
3233 
3234 // This is the task used for parallel heap verification.
3235 
3236 class G1ParVerifyTask: public AbstractGangTask {
3237 private:
3238   G1CollectedHeap* _g1h;
3239   VerifyOption     _vo;
3240   bool             _failures;
3241 
3242 public:
3243   // _vo == UsePrevMarking -> use "prev" marking information,
3244   // _vo == UseNextMarking -> use "next" marking information,
3245   // _vo == UseMarkWord    -> use mark word from object header.
3246   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3247     AbstractGangTask("Parallel verify task"),
3248     _g1h(g1h),
3249     _vo(vo),
3250     _failures(false) { }
3251 
3252   bool failures() {
3253     return _failures;
3254   }
3255 
3256   void work(uint worker_id) {
3257     HandleMark hm;
3258     VerifyRegionClosure blk(true, _vo);
3259     _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3260                                           _g1h->workers()->active_workers(),
3261                                           HeapRegion::ParVerifyClaimValue);
3262     if (blk.failures()) {
3263       _failures = true;
3264     }
3265   }
3266 };
3267 
3268 void G1CollectedHeap::verify(bool silent) {
3269   verify(silent, VerifyOption_G1UsePrevMarking);
3270 }
3271 
3272 void G1CollectedHeap::verify(bool silent,
3273                              VerifyOption vo) {
3274   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3275     if (!silent) { gclog_or_tty->print("Roots "); }
3276     VerifyRootsClosure rootsCl(vo);
3277 
3278     assert(Thread::current()->is_VM_thread(),
3279       "Expected to be executed serially by the VM thread at this point");
3280 
3281     CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
3282     VerifyKlassClosure klassCl(this, &rootsCl);
3283 
3284     // We apply the relevant closures to all the oops in the
3285     // system dictionary, the string table and the code cache.
3286     const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3287 
3288     // Need cleared claim bits for the strong roots processing
3289     ClassLoaderDataGraph::clear_claimed_marks();
3290 
3291     process_strong_roots(true,      // activate StrongRootsScope
3292                          false,     // we set "is scavenging" to false,
3293                                     // so we don't reset the dirty cards.
3294                          ScanningOption(so),  // roots scanning options
3295                          &rootsCl,
3296                          &blobsCl,
3297                          &klassCl
3298                          );
3299 
3300     bool failures = rootsCl.failures();
3301 
3302     if (vo != VerifyOption_G1UseMarkWord) {
3303       // If we're verifying during a full GC then the region sets
3304       // will have been torn down at the start of the GC. Therefore
3305       // verifying the region sets will fail. So we only verify
3306       // the region sets when not in a full GC.
3307       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3308       verify_region_sets();
3309     }
3310 
3311     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3312     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3313       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3314              "sanity check");
3315 
3316       G1ParVerifyTask task(this, vo);
3317       assert(UseDynamicNumberOfGCThreads ||
3318         workers()->active_workers() == workers()->total_workers(),
3319         "If not dynamic should be using all the workers");
3320       int n_workers = workers()->active_workers();
3321       set_par_threads(n_workers);
3322       workers()->run_task(&task);
3323       set_par_threads(0);
3324       if (task.failures()) {
3325         failures = true;
3326       }
3327 
3328       // Checks that the expected amount of parallel work was done.
3329       // The implication is that n_workers is > 0.
3330       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3331              "sanity check");
3332 
3333       reset_heap_region_claim_values();
3334 
3335       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3336              "sanity check");
3337     } else {
3338       VerifyRegionClosure blk(false, vo);
3339       heap_region_iterate(&blk);
3340       if (blk.failures()) {
3341         failures = true;
3342       }
3343     }
3344     if (!silent) gclog_or_tty->print("RemSet ");
3345     rem_set()->verify();
3346 
3347     if (failures) {
3348       gclog_or_tty->print_cr("Heap:");
3349       // It helps to have the per-region information in the output to
3350       // help us track down what went wrong. This is why we call
3351       // print_extended_on() instead of print_on().
3352       print_extended_on(gclog_or_tty);
3353       gclog_or_tty->print_cr("");
3354 #ifndef PRODUCT
3355       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3356         concurrent_mark()->print_reachable("at-verification-failure",
3357                                            vo, false /* all */);
3358       }
3359 #endif
3360       gclog_or_tty->flush();
3361     }
3362     guarantee(!failures, "there should not have been any failures");
3363   } else {
3364     if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
3365   }
3366 }
3367 
3368 class PrintRegionClosure: public HeapRegionClosure {
3369   outputStream* _st;
3370 public:
3371   PrintRegionClosure(outputStream* st) : _st(st) {}
3372   bool doHeapRegion(HeapRegion* r) {
3373     r->print_on(_st);
3374     return false;
3375   }
3376 };
3377 
3378 void G1CollectedHeap::print_on(outputStream* st) const {
3379   st->print(" %-20s", "garbage-first heap");
3380   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3381             capacity()/K, used_unlocked()/K);
3382   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3383             _g1_storage.low_boundary(),
3384             _g1_storage.high(),
3385             _g1_storage.high_boundary());
3386   st->cr();
3387   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3388   uint young_regions = _young_list->length();
3389   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3390             (size_t) young_regions * HeapRegion::GrainBytes / K);
3391   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3392   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3393             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3394   st->cr();
3395   MetaspaceAux::print_on(st);
3396 }
3397 
3398 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3399   print_on(st);
3400 
3401   // Print the per-region information.
3402   st->cr();
3403   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3404                "HS=humongous(starts), HC=humongous(continues), "
3405                "CS=collection set, F=free, TS=gc time stamp, "
3406                "PTAMS=previous top-at-mark-start, "
3407                "NTAMS=next top-at-mark-start)");
3408   PrintRegionClosure blk(st);
3409   heap_region_iterate(&blk);
3410 }
3411 
3412 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3413   if (G1CollectedHeap::use_parallel_gc_threads()) {
3414     workers()->print_worker_threads_on(st);
3415   }
3416   _cmThread->print_on(st);
3417   st->cr();
3418   _cm->print_worker_threads_on(st);
3419   _cg1r->print_worker_threads_on(st);
3420 }
3421 
3422 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3423   if (G1CollectedHeap::use_parallel_gc_threads()) {
3424     workers()->threads_do(tc);
3425   }
3426   tc->do_thread(_cmThread);
3427   _cg1r->threads_do(tc);
3428 }
3429 
3430 void G1CollectedHeap::print_tracing_info() const {
3431   // We'll overload this to mean "trace GC pause statistics."
3432   if (TraceGen0Time || TraceGen1Time) {
3433     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3434     // to that.
3435     g1_policy()->print_tracing_info();
3436   }
3437   if (G1SummarizeRSetStats) {
3438     g1_rem_set()->print_summary_info();
3439   }
3440   if (G1SummarizeConcMark) {
3441     concurrent_mark()->print_summary_info();
3442   }
3443   g1_policy()->print_yg_surv_rate_info();
3444   SpecializationStats::print();
3445 }
3446 
3447 #ifndef PRODUCT
3448 // Helpful for debugging RSet issues.
3449 
3450 class PrintRSetsClosure : public HeapRegionClosure {
3451 private:
3452   const char* _msg;
3453   size_t _occupied_sum;
3454 
3455 public:
3456   bool doHeapRegion(HeapRegion* r) {
3457     HeapRegionRemSet* hrrs = r->rem_set();
3458     size_t occupied = hrrs->occupied();
3459     _occupied_sum += occupied;
3460 
3461     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3462                            HR_FORMAT_PARAMS(r));
3463     if (occupied == 0) {
3464       gclog_or_tty->print_cr("  RSet is empty");
3465     } else {
3466       hrrs->print();
3467     }
3468     gclog_or_tty->print_cr("----------");
3469     return false;
3470   }
3471 
3472   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3473     gclog_or_tty->cr();
3474     gclog_or_tty->print_cr("========================================");
3475     gclog_or_tty->print_cr(msg);
3476     gclog_or_tty->cr();
3477   }
3478 
3479   ~PrintRSetsClosure() {
3480     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3481     gclog_or_tty->print_cr("========================================");
3482     gclog_or_tty->cr();
3483   }
3484 };
3485 
3486 void G1CollectedHeap::print_cset_rsets() {
3487   PrintRSetsClosure cl("Printing CSet RSets");
3488   collection_set_iterate(&cl);
3489 }
3490 
3491 void G1CollectedHeap::print_all_rsets() {
3492   PrintRSetsClosure cl("Printing All RSets");;
3493   heap_region_iterate(&cl);
3494 }
3495 #endif // PRODUCT
3496 
3497 G1CollectedHeap* G1CollectedHeap::heap() {
3498   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3499          "not a garbage-first heap");
3500   return _g1h;
3501 }
3502 
3503 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3504   // always_do_update_barrier = false;
3505   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3506   // Call allocation profiler
3507   AllocationProfiler::iterate_since_last_gc();
3508   // Fill TLAB's and such
3509   ensure_parsability(true);
3510 }
3511 
3512 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3513   // FIXME: what is this about?
3514   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3515   // is set.
3516   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3517                         "derived pointer present"));
3518   // always_do_update_barrier = true;
3519 
3520   // We have just completed a GC. Update the soft reference
3521   // policy with the new heap occupancy
3522   Universe::update_heap_info_at_gc();
3523 }
3524 
3525 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3526                                                unsigned int gc_count_before,
3527                                                bool* succeeded) {
3528   assert_heap_not_locked_and_not_at_safepoint();
3529   g1_policy()->record_stop_world_start();
3530   VM_G1IncCollectionPause op(gc_count_before,
3531                              word_size,
3532                              false, /* should_initiate_conc_mark */
3533                              g1_policy()->max_pause_time_ms(),
3534                              GCCause::_g1_inc_collection_pause);
3535   VMThread::execute(&op);
3536 
3537   HeapWord* result = op.result();
3538   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3539   assert(result == NULL || ret_succeeded,
3540          "the result should be NULL if the VM did not succeed");
3541   *succeeded = ret_succeeded;
3542 
3543   assert_heap_not_locked();
3544   return result;
3545 }
3546 
3547 void
3548 G1CollectedHeap::doConcurrentMark() {
3549   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3550   if (!_cmThread->in_progress()) {
3551     _cmThread->set_started();
3552     CGC_lock->notify();
3553   }
3554 }
3555 
3556 size_t G1CollectedHeap::pending_card_num() {
3557   size_t extra_cards = 0;
3558   JavaThread *curr = Threads::first();
3559   while (curr != NULL) {
3560     DirtyCardQueue& dcq = curr->dirty_card_queue();
3561     extra_cards += dcq.size();
3562     curr = curr->next();
3563   }
3564   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3565   size_t buffer_size = dcqs.buffer_size();
3566   size_t buffer_num = dcqs.completed_buffers_num();
3567 
3568   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3569   // in bytes - not the number of 'entries'. We need to convert
3570   // into a number of cards.
3571   return (buffer_size * buffer_num + extra_cards) / oopSize;
3572 }
3573 
3574 size_t G1CollectedHeap::cards_scanned() {
3575   return g1_rem_set()->cardsScanned();
3576 }
3577 
3578 void
3579 G1CollectedHeap::setup_surviving_young_words() {
3580   assert(_surviving_young_words == NULL, "pre-condition");
3581   uint array_length = g1_policy()->young_cset_region_length();
3582   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3583   if (_surviving_young_words == NULL) {
3584     vm_exit_out_of_memory(sizeof(size_t) * array_length,
3585                           "Not enough space for young surv words summary.");
3586   }
3587   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3588 #ifdef ASSERT
3589   for (uint i = 0;  i < array_length; ++i) {
3590     assert( _surviving_young_words[i] == 0, "memset above" );
3591   }
3592 #endif // !ASSERT
3593 }
3594 
3595 void
3596 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3597   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3598   uint array_length = g1_policy()->young_cset_region_length();
3599   for (uint i = 0; i < array_length; ++i) {
3600     _surviving_young_words[i] += surv_young_words[i];
3601   }
3602 }
3603 
3604 void
3605 G1CollectedHeap::cleanup_surviving_young_words() {
3606   guarantee( _surviving_young_words != NULL, "pre-condition" );
3607   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3608   _surviving_young_words = NULL;
3609 }
3610 
3611 #ifdef ASSERT
3612 class VerifyCSetClosure: public HeapRegionClosure {
3613 public:
3614   bool doHeapRegion(HeapRegion* hr) {
3615     // Here we check that the CSet region's RSet is ready for parallel
3616     // iteration. The fields that we'll verify are only manipulated
3617     // when the region is part of a CSet and is collected. Afterwards,
3618     // we reset these fields when we clear the region's RSet (when the
3619     // region is freed) so they are ready when the region is
3620     // re-allocated. The only exception to this is if there's an
3621     // evacuation failure and instead of freeing the region we leave
3622     // it in the heap. In that case, we reset these fields during
3623     // evacuation failure handling.
3624     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3625 
3626     // Here's a good place to add any other checks we'd like to
3627     // perform on CSet regions.
3628     return false;
3629   }
3630 };
3631 #endif // ASSERT
3632 
3633 #if TASKQUEUE_STATS
3634 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3635   st->print_raw_cr("GC Task Stats");
3636   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3637   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3638 }
3639 
3640 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3641   print_taskqueue_stats_hdr(st);
3642 
3643   TaskQueueStats totals;
3644   const int n = workers() != NULL ? workers()->total_workers() : 1;
3645   for (int i = 0; i < n; ++i) {
3646     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3647     totals += task_queue(i)->stats;
3648   }
3649   st->print_raw("tot "); totals.print(st); st->cr();
3650 
3651   DEBUG_ONLY(totals.verify());
3652 }
3653 
3654 void G1CollectedHeap::reset_taskqueue_stats() {
3655   const int n = workers() != NULL ? workers()->total_workers() : 1;
3656   for (int i = 0; i < n; ++i) {
3657     task_queue(i)->stats.reset();
3658   }
3659 }
3660 #endif // TASKQUEUE_STATS
3661 
3662 void G1CollectedHeap::log_gc_header() {
3663   if (!G1Log::fine()) {
3664     return;
3665   }
3666 
3667   gclog_or_tty->date_stamp(PrintGCDateStamps);
3668   gclog_or_tty->stamp(PrintGCTimeStamps);
3669 
3670   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3671     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3672     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3673 
3674   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3675 }
3676 
3677 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3678   if (!G1Log::fine()) {
3679     return;
3680   }
3681 
3682   if (G1Log::finer()) {
3683     if (evacuation_failed()) {
3684       gclog_or_tty->print(" (to-space exhausted)");
3685     }
3686     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3687     g1_policy()->phase_times()->note_gc_end();
3688     g1_policy()->phase_times()->print(pause_time_sec);
3689     g1_policy()->print_detailed_heap_transition();
3690   } else {
3691     if (evacuation_failed()) {
3692       gclog_or_tty->print("--");
3693     }
3694     g1_policy()->print_heap_transition();
3695     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3696   }
3697   gclog_or_tty->flush();
3698 }
3699 
3700 bool
3701 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3702   assert_at_safepoint(true /* should_be_vm_thread */);
3703   guarantee(!is_gc_active(), "collection is not reentrant");
3704 
3705   if (GC_locker::check_active_before_gc()) {
3706     return false;
3707   }
3708 
3709   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3710   ResourceMark rm;
3711 
3712   print_heap_before_gc();
3713 
3714   HRSPhaseSetter x(HRSPhaseEvacuation);
3715   verify_region_sets_optional();
3716   verify_dirty_young_regions();
3717 
3718   // This call will decide whether this pause is an initial-mark
3719   // pause. If it is, during_initial_mark_pause() will return true
3720   // for the duration of this pause.
3721   g1_policy()->decide_on_conc_mark_initiation();
3722 
3723   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3724   assert(!g1_policy()->during_initial_mark_pause() ||
3725           g1_policy()->gcs_are_young(), "sanity");
3726 
3727   // We also do not allow mixed GCs during marking.
3728   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3729 
3730   // Record whether this pause is an initial mark. When the current
3731   // thread has completed its logging output and it's safe to signal
3732   // the CM thread, the flag's value in the policy has been reset.
3733   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3734 
3735   // Inner scope for scope based logging, timers, and stats collection
3736   {
3737     if (g1_policy()->during_initial_mark_pause()) {
3738       // We are about to start a marking cycle, so we increment the
3739       // full collection counter.
3740       increment_old_marking_cycles_started();
3741     }
3742     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3743 
3744     int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3745                                 workers()->active_workers() : 1);
3746     double pause_start_sec = os::elapsedTime();
3747     g1_policy()->phase_times()->note_gc_start(active_workers);
3748     log_gc_header();
3749 
3750     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3751     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3752 
3753     // If the secondary_free_list is not empty, append it to the
3754     // free_list. No need to wait for the cleanup operation to finish;
3755     // the region allocation code will check the secondary_free_list
3756     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3757     // set, skip this step so that the region allocation code has to
3758     // get entries from the secondary_free_list.
3759     if (!G1StressConcRegionFreeing) {
3760       append_secondary_free_list_if_not_empty_with_lock();
3761     }
3762 
3763     assert(check_young_list_well_formed(),
3764       "young list should be well formed");
3765 
3766     // Don't dynamically change the number of GC threads this early.  A value of
3767     // 0 is used to indicate serial work.  When parallel work is done,
3768     // it will be set.
3769 
3770     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3771       IsGCActiveMark x;
3772 
3773       gc_prologue(false);
3774       increment_total_collections(false /* full gc */);
3775       increment_gc_time_stamp();
3776 
3777       verify_before_gc();
3778 
3779       COMPILER2_PRESENT(DerivedPointerTable::clear());
3780 
3781       // Please see comment in g1CollectedHeap.hpp and
3782       // G1CollectedHeap::ref_processing_init() to see how
3783       // reference processing currently works in G1.
3784 
3785       // Enable discovery in the STW reference processor
3786       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3787                                             true /*verify_no_refs*/);
3788 
3789       {
3790         // We want to temporarily turn off discovery by the
3791         // CM ref processor, if necessary, and turn it back on
3792         // on again later if we do. Using a scoped
3793         // NoRefDiscovery object will do this.
3794         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3795 
3796         // Forget the current alloc region (we might even choose it to be part
3797         // of the collection set!).
3798         release_mutator_alloc_region();
3799 
3800         // We should call this after we retire the mutator alloc
3801         // region(s) so that all the ALLOC / RETIRE events are generated
3802         // before the start GC event.
3803         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3804 
3805         // This timing is only used by the ergonomics to handle our pause target.
3806         // It is unclear why this should not include the full pause. We will
3807         // investigate this in CR 7178365.
3808         //
3809         // Preserving the old comment here if that helps the investigation:
3810         //
3811         // The elapsed time induced by the start time below deliberately elides
3812         // the possible verification above.
3813         double sample_start_time_sec = os::elapsedTime();
3814         size_t start_used_bytes = used();
3815 
3816 #if YOUNG_LIST_VERBOSE
3817         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3818         _young_list->print();
3819         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3820 #endif // YOUNG_LIST_VERBOSE
3821 
3822         g1_policy()->record_collection_pause_start(sample_start_time_sec,
3823                                                    start_used_bytes);
3824 
3825         double scan_wait_start = os::elapsedTime();
3826         // We have to wait until the CM threads finish scanning the
3827         // root regions as it's the only way to ensure that all the
3828         // objects on them have been correctly scanned before we start
3829         // moving them during the GC.
3830         bool waited = _cm->root_regions()->wait_until_scan_finished();
3831         double wait_time_ms = 0.0;
3832         if (waited) {
3833           double scan_wait_end = os::elapsedTime();
3834           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3835         }
3836         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3837 
3838 #if YOUNG_LIST_VERBOSE
3839         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3840         _young_list->print();
3841 #endif // YOUNG_LIST_VERBOSE
3842 
3843         if (g1_policy()->during_initial_mark_pause()) {
3844           concurrent_mark()->checkpointRootsInitialPre();
3845         }
3846 
3847 #if YOUNG_LIST_VERBOSE
3848         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3849         _young_list->print();
3850         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3851 #endif // YOUNG_LIST_VERBOSE
3852 
3853         g1_policy()->finalize_cset(target_pause_time_ms);
3854 
3855         _cm->note_start_of_gc();
3856         // We should not verify the per-thread SATB buffers given that
3857         // we have not filtered them yet (we'll do so during the
3858         // GC). We also call this after finalize_cset() to
3859         // ensure that the CSet has been finalized.
3860         _cm->verify_no_cset_oops(true  /* verify_stacks */,
3861                                  true  /* verify_enqueued_buffers */,
3862                                  false /* verify_thread_buffers */,
3863                                  true  /* verify_fingers */);
3864 
3865         if (_hr_printer.is_active()) {
3866           HeapRegion* hr = g1_policy()->collection_set();
3867           while (hr != NULL) {
3868             G1HRPrinter::RegionType type;
3869             if (!hr->is_young()) {
3870               type = G1HRPrinter::Old;
3871             } else if (hr->is_survivor()) {
3872               type = G1HRPrinter::Survivor;
3873             } else {
3874               type = G1HRPrinter::Eden;
3875             }
3876             _hr_printer.cset(hr);
3877             hr = hr->next_in_collection_set();
3878           }
3879         }
3880 
3881 #ifdef ASSERT
3882         VerifyCSetClosure cl;
3883         collection_set_iterate(&cl);
3884 #endif // ASSERT
3885 
3886         setup_surviving_young_words();
3887 
3888         // Initialize the GC alloc regions.
3889         init_gc_alloc_regions();
3890 
3891         // Actually do the work...
3892         evacuate_collection_set();
3893 
3894         // We do this to mainly verify the per-thread SATB buffers
3895         // (which have been filtered by now) since we didn't verify
3896         // them earlier. No point in re-checking the stacks / enqueued
3897         // buffers given that the CSet has not changed since last time
3898         // we checked.
3899         _cm->verify_no_cset_oops(false /* verify_stacks */,
3900                                  false /* verify_enqueued_buffers */,
3901                                  true  /* verify_thread_buffers */,
3902                                  true  /* verify_fingers */);
3903 
3904         free_collection_set(g1_policy()->collection_set());
3905         g1_policy()->clear_collection_set();
3906 
3907         cleanup_surviving_young_words();
3908 
3909         // Start a new incremental collection set for the next pause.
3910         g1_policy()->start_incremental_cset_building();
3911 
3912         // Clear the _cset_fast_test bitmap in anticipation of adding
3913         // regions to the incremental collection set for the next
3914         // evacuation pause.
3915         clear_cset_fast_test();
3916 
3917         _young_list->reset_sampled_info();
3918 
3919         // Don't check the whole heap at this point as the
3920         // GC alloc regions from this pause have been tagged
3921         // as survivors and moved on to the survivor list.
3922         // Survivor regions will fail the !is_young() check.
3923         assert(check_young_list_empty(false /* check_heap */),
3924           "young list should be empty");
3925 
3926 #if YOUNG_LIST_VERBOSE
3927         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3928         _young_list->print();
3929 #endif // YOUNG_LIST_VERBOSE
3930 
3931         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3932                                             _young_list->first_survivor_region(),
3933                                             _young_list->last_survivor_region());
3934 
3935         _young_list->reset_auxilary_lists();
3936 
3937         if (evacuation_failed()) {
3938           _summary_bytes_used = recalculate_used();
3939         } else {
3940           // The "used" of the the collection set have already been subtracted
3941           // when they were freed.  Add in the bytes evacuated.
3942           _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
3943         }
3944 
3945         if (g1_policy()->during_initial_mark_pause()) {
3946           // We have to do this before we notify the CM threads that
3947           // they can start working to make sure that all the
3948           // appropriate initialization is done on the CM object.
3949           concurrent_mark()->checkpointRootsInitialPost();
3950           set_marking_started();
3951           // Note that we don't actually trigger the CM thread at
3952           // this point. We do that later when we're sure that
3953           // the current thread has completed its logging output.
3954         }
3955 
3956         allocate_dummy_regions();
3957 
3958 #if YOUNG_LIST_VERBOSE
3959         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3960         _young_list->print();
3961         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3962 #endif // YOUNG_LIST_VERBOSE
3963 
3964         init_mutator_alloc_region();
3965 
3966         {
3967           size_t expand_bytes = g1_policy()->expansion_amount();
3968           if (expand_bytes > 0) {
3969             size_t bytes_before = capacity();
3970             // No need for an ergo verbose message here,
3971             // expansion_amount() does this when it returns a value > 0.
3972             if (!expand(expand_bytes)) {
3973               // We failed to expand the heap so let's verify that
3974               // committed/uncommitted amount match the backing store
3975               assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3976               assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3977             }
3978           }
3979         }
3980 
3981         // We redo the verificaiton but now wrt to the new CSet which
3982         // has just got initialized after the previous CSet was freed.
3983         _cm->verify_no_cset_oops(true  /* verify_stacks */,
3984                                  true  /* verify_enqueued_buffers */,
3985                                  true  /* verify_thread_buffers */,
3986                                  true  /* verify_fingers */);
3987         _cm->note_end_of_gc();
3988 
3989         // This timing is only used by the ergonomics to handle our pause target.
3990         // It is unclear why this should not include the full pause. We will
3991         // investigate this in CR 7178365.
3992         double sample_end_time_sec = os::elapsedTime();
3993         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3994         g1_policy()->record_collection_pause_end(pause_time_ms);
3995 
3996         MemoryService::track_memory_usage();
3997 
3998         // In prepare_for_verify() below we'll need to scan the deferred
3999         // update buffers to bring the RSets up-to-date if
4000         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4001         // the update buffers we'll probably need to scan cards on the
4002         // regions we just allocated to (i.e., the GC alloc
4003         // regions). However, during the last GC we called
4004         // set_saved_mark() on all the GC alloc regions, so card
4005         // scanning might skip the [saved_mark_word()...top()] area of
4006         // those regions (i.e., the area we allocated objects into
4007         // during the last GC). But it shouldn't. Given that
4008         // saved_mark_word() is conditional on whether the GC time stamp
4009         // on the region is current or not, by incrementing the GC time
4010         // stamp here we invalidate all the GC time stamps on all the
4011         // regions and saved_mark_word() will simply return top() for
4012         // all the regions. This is a nicer way of ensuring this rather
4013         // than iterating over the regions and fixing them. In fact, the
4014         // GC time stamp increment here also ensures that
4015         // saved_mark_word() will return top() between pauses, i.e.,
4016         // during concurrent refinement. So we don't need the
4017         // is_gc_active() check to decided which top to use when
4018         // scanning cards (see CR 7039627).
4019         increment_gc_time_stamp();
4020 
4021         verify_after_gc();
4022 
4023         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4024         ref_processor_stw()->verify_no_references_recorded();
4025 
4026         // CM reference discovery will be re-enabled if necessary.
4027       }
4028 
4029       // We should do this after we potentially expand the heap so
4030       // that all the COMMIT events are generated before the end GC
4031       // event, and after we retire the GC alloc regions so that all
4032       // RETIRE events are generated before the end GC event.
4033       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4034 
4035       if (mark_in_progress()) {
4036         concurrent_mark()->update_g1_committed();
4037       }
4038 
4039 #ifdef TRACESPINNING
4040       ParallelTaskTerminator::print_termination_counts();
4041 #endif
4042 
4043       gc_epilogue(false);
4044     }
4045 
4046     // Print the remainder of the GC log output.
4047     log_gc_footer(os::elapsedTime() - pause_start_sec);
4048 
4049     // It is not yet to safe to tell the concurrent mark to
4050     // start as we have some optional output below. We don't want the
4051     // output from the concurrent mark thread interfering with this
4052     // logging output either.
4053 
4054     _hrs.verify_optional();
4055     verify_region_sets_optional();
4056 
4057     TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4058     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4059 
4060     print_heap_after_gc();
4061 
4062     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4063     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4064     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4065     // before any GC notifications are raised.
4066     g1mm()->update_sizes();
4067   }
4068 
4069   if (G1SummarizeRSetStats &&
4070       (G1SummarizeRSetStatsPeriod > 0) &&
4071       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
4072     g1_rem_set()->print_summary_info();
4073   }
4074 
4075   // It should now be safe to tell the concurrent mark thread to start
4076   // without its logging output interfering with the logging output
4077   // that came from the pause.
4078 
4079   if (should_start_conc_mark) {
4080     // CAUTION: after the doConcurrentMark() call below,
4081     // the concurrent marking thread(s) could be running
4082     // concurrently with us. Make sure that anything after
4083     // this point does not assume that we are the only GC thread
4084     // running. Note: of course, the actual marking work will
4085     // not start until the safepoint itself is released in
4086     // ConcurrentGCThread::safepoint_desynchronize().
4087     doConcurrentMark();
4088   }
4089 
4090   return true;
4091 }
4092 
4093 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4094 {
4095   size_t gclab_word_size;
4096   switch (purpose) {
4097     case GCAllocForSurvived:
4098       gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4099       break;
4100     case GCAllocForTenured:
4101       gclab_word_size = _old_plab_stats.desired_plab_sz();
4102       break;
4103     default:
4104       assert(false, "unknown GCAllocPurpose");
4105       gclab_word_size = _old_plab_stats.desired_plab_sz();
4106       break;
4107   }
4108 
4109   // Prevent humongous PLAB sizes for two reasons:
4110   // * PLABs are allocated using a similar paths as oops, but should
4111   //   never be in a humongous region
4112   // * Allowing humongous PLABs needlessly churns the region free lists
4113   return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4114 }
4115 
4116 void G1CollectedHeap::init_mutator_alloc_region() {
4117   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4118   _mutator_alloc_region.init();
4119 }
4120 
4121 void G1CollectedHeap::release_mutator_alloc_region() {
4122   _mutator_alloc_region.release();
4123   assert(_mutator_alloc_region.get() == NULL, "post-condition");
4124 }
4125 
4126 void G1CollectedHeap::init_gc_alloc_regions() {
4127   assert_at_safepoint(true /* should_be_vm_thread */);
4128 
4129   _survivor_gc_alloc_region.init();
4130   _old_gc_alloc_region.init();
4131   HeapRegion* retained_region = _retained_old_gc_alloc_region;
4132   _retained_old_gc_alloc_region = NULL;
4133 
4134   // We will discard the current GC alloc region if:
4135   // a) it's in the collection set (it can happen!),
4136   // b) it's already full (no point in using it),
4137   // c) it's empty (this means that it was emptied during
4138   // a cleanup and it should be on the free list now), or
4139   // d) it's humongous (this means that it was emptied
4140   // during a cleanup and was added to the free list, but
4141   // has been subseqently used to allocate a humongous
4142   // object that may be less than the region size).
4143   if (retained_region != NULL &&
4144       !retained_region->in_collection_set() &&
4145       !(retained_region->top() == retained_region->end()) &&
4146       !retained_region->is_empty() &&
4147       !retained_region->isHumongous()) {
4148     retained_region->set_saved_mark();
4149     // The retained region was added to the old region set when it was
4150     // retired. We have to remove it now, since we don't allow regions
4151     // we allocate to in the region sets. We'll re-add it later, when
4152     // it's retired again.
4153     _old_set.remove(retained_region);
4154     bool during_im = g1_policy()->during_initial_mark_pause();
4155     retained_region->note_start_of_copying(during_im);
4156     _old_gc_alloc_region.set(retained_region);
4157     _hr_printer.reuse(retained_region);
4158   }
4159 }
4160 
4161 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers) {
4162   _survivor_gc_alloc_region.release();
4163   // If we have an old GC alloc region to release, we'll save it in
4164   // _retained_old_gc_alloc_region. If we don't
4165   // _retained_old_gc_alloc_region will become NULL. This is what we
4166   // want either way so no reason to check explicitly for either
4167   // condition.
4168   _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4169 
4170   if (ResizePLAB) {
4171     _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4172     _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4173   }
4174 }
4175 
4176 void G1CollectedHeap::abandon_gc_alloc_regions() {
4177   assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4178   assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4179   _retained_old_gc_alloc_region = NULL;
4180 }
4181 
4182 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4183   _drain_in_progress = false;
4184   set_evac_failure_closure(cl);
4185   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4186 }
4187 
4188 void G1CollectedHeap::finalize_for_evac_failure() {
4189   assert(_evac_failure_scan_stack != NULL &&
4190          _evac_failure_scan_stack->length() == 0,
4191          "Postcondition");
4192   assert(!_drain_in_progress, "Postcondition");
4193   delete _evac_failure_scan_stack;
4194   _evac_failure_scan_stack = NULL;
4195 }
4196 
4197 void G1CollectedHeap::remove_self_forwarding_pointers() {
4198   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4199 
4200   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4201 
4202   if (G1CollectedHeap::use_parallel_gc_threads()) {
4203     set_par_threads();
4204     workers()->run_task(&rsfp_task);
4205     set_par_threads(0);
4206   } else {
4207     rsfp_task.work(0);
4208   }
4209 
4210   assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4211 
4212   // Reset the claim values in the regions in the collection set.
4213   reset_cset_heap_region_claim_values();
4214 
4215   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4216 
4217   // Now restore saved marks, if any.
4218   if (_objs_with_preserved_marks != NULL) {
4219     assert(_preserved_marks_of_objs != NULL, "Both or none.");
4220     guarantee(_objs_with_preserved_marks->length() ==
4221               _preserved_marks_of_objs->length(), "Both or none.");
4222     for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
4223       oop obj   = _objs_with_preserved_marks->at(i);
4224       markOop m = _preserved_marks_of_objs->at(i);
4225       obj->set_mark(m);
4226     }
4227 
4228     // Delete the preserved marks growable arrays (allocated on the C heap).
4229     delete _objs_with_preserved_marks;
4230     delete _preserved_marks_of_objs;
4231     _objs_with_preserved_marks = NULL;
4232     _preserved_marks_of_objs = NULL;
4233   }
4234 }
4235 
4236 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4237   _evac_failure_scan_stack->push(obj);
4238 }
4239 
4240 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4241   assert(_evac_failure_scan_stack != NULL, "precondition");
4242 
4243   while (_evac_failure_scan_stack->length() > 0) {
4244      oop obj = _evac_failure_scan_stack->pop();
4245      _evac_failure_closure->set_region(heap_region_containing(obj));
4246      obj->oop_iterate_backwards(_evac_failure_closure);
4247   }
4248 }
4249 
4250 oop
4251 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
4252                                                oop old) {
4253   assert(obj_in_cs(old),
4254          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4255                  (HeapWord*) old));
4256   markOop m = old->mark();
4257   oop forward_ptr = old->forward_to_atomic(old);
4258   if (forward_ptr == NULL) {
4259     // Forward-to-self succeeded.
4260 
4261     if (_evac_failure_closure != cl) {
4262       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4263       assert(!_drain_in_progress,
4264              "Should only be true while someone holds the lock.");
4265       // Set the global evac-failure closure to the current thread's.
4266       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4267       set_evac_failure_closure(cl);
4268       // Now do the common part.
4269       handle_evacuation_failure_common(old, m);
4270       // Reset to NULL.
4271       set_evac_failure_closure(NULL);
4272     } else {
4273       // The lock is already held, and this is recursive.
4274       assert(_drain_in_progress, "This should only be the recursive case.");
4275       handle_evacuation_failure_common(old, m);
4276     }
4277     return old;
4278   } else {
4279     // Forward-to-self failed. Either someone else managed to allocate
4280     // space for this object (old != forward_ptr) or they beat us in
4281     // self-forwarding it (old == forward_ptr).
4282     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4283            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4284                    "should not be in the CSet",
4285                    (HeapWord*) old, (HeapWord*) forward_ptr));
4286     return forward_ptr;
4287   }
4288 }
4289 
4290 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4291   set_evacuation_failed(true);
4292 
4293   preserve_mark_if_necessary(old, m);
4294 
4295   HeapRegion* r = heap_region_containing(old);
4296   if (!r->evacuation_failed()) {
4297     r->set_evacuation_failed(true);
4298     _hr_printer.evac_failure(r);
4299   }
4300 
4301   push_on_evac_failure_scan_stack(old);
4302 
4303   if (!_drain_in_progress) {
4304     // prevent recursion in copy_to_survivor_space()
4305     _drain_in_progress = true;
4306     drain_evac_failure_scan_stack();
4307     _drain_in_progress = false;
4308   }
4309 }
4310 
4311 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4312   assert(evacuation_failed(), "Oversaving!");
4313   // We want to call the "for_promotion_failure" version only in the
4314   // case of a promotion failure.
4315   if (m->must_be_preserved_for_promotion_failure(obj)) {
4316     if (_objs_with_preserved_marks == NULL) {
4317       assert(_preserved_marks_of_objs == NULL, "Both or none.");
4318       _objs_with_preserved_marks =
4319         new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4320       _preserved_marks_of_objs =
4321         new (ResourceObj::C_HEAP, mtGC) GrowableArray<markOop>(40, true);
4322     }
4323     _objs_with_preserved_marks->push(obj);
4324     _preserved_marks_of_objs->push(m);
4325   }
4326 }
4327 
4328 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4329                                                   size_t word_size) {
4330   if (purpose == GCAllocForSurvived) {
4331     HeapWord* result = survivor_attempt_allocation(word_size);
4332     if (result != NULL) {
4333       return result;
4334     } else {
4335       // Let's try to allocate in the old gen in case we can fit the
4336       // object there.
4337       return old_attempt_allocation(word_size);
4338     }
4339   } else {
4340     assert(purpose ==  GCAllocForTenured, "sanity");
4341     HeapWord* result = old_attempt_allocation(word_size);
4342     if (result != NULL) {
4343       return result;
4344     } else {
4345       // Let's try to allocate in the survivors in case we can fit the
4346       // object there.
4347       return survivor_attempt_allocation(word_size);
4348     }
4349   }
4350 
4351   ShouldNotReachHere();
4352   // Trying to keep some compilers happy.
4353   return NULL;
4354 }
4355 
4356 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4357   ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4358 
4359 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4360   : _g1h(g1h),
4361     _refs(g1h->task_queue(queue_num)),
4362     _dcq(&g1h->dirty_card_queue_set()),
4363     _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4364     _g1_rem(g1h->g1_rem_set()),
4365     _hash_seed(17), _queue_num(queue_num),
4366     _term_attempts(0),
4367     _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4368     _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4369     _age_table(false),
4370     _strong_roots_time(0), _term_time(0),
4371     _alloc_buffer_waste(0), _undo_waste(0) {
4372   // we allocate G1YoungSurvRateNumRegions plus one entries, since
4373   // we "sacrifice" entry 0 to keep track of surviving bytes for
4374   // non-young regions (where the age is -1)
4375   // We also add a few elements at the beginning and at the end in
4376   // an attempt to eliminate cache contention
4377   uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4378   uint array_length = PADDING_ELEM_NUM +
4379                       real_length +
4380                       PADDING_ELEM_NUM;
4381   _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4382   if (_surviving_young_words_base == NULL)
4383     vm_exit_out_of_memory(array_length * sizeof(size_t),
4384                           "Not enough space for young surv histo.");
4385   _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4386   memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4387 
4388   _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4389   _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;
4390 
4391   _start = os::elapsedTime();
4392 }
4393 
4394 void
4395 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4396 {
4397   st->print_raw_cr("GC Termination Stats");
4398   st->print_raw_cr("     elapsed  --strong roots-- -------termination-------"
4399                    " ------waste (KiB)------");
4400   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts"
4401                    "  total   alloc    undo");
4402   st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4403                    " ------- ------- -------");
4404 }
4405 
4406 void
4407 G1ParScanThreadState::print_termination_stats(int i,
4408                                               outputStream* const st) const
4409 {
4410   const double elapsed_ms = elapsed_time() * 1000.0;
4411   const double s_roots_ms = strong_roots_time() * 1000.0;
4412   const double term_ms    = term_time() * 1000.0;
4413   st->print_cr("%3d %9.2f %9.2f %6.2f "
4414                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4415                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4416                i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4417                term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4418                (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4419                alloc_buffer_waste() * HeapWordSize / K,
4420                undo_waste() * HeapWordSize / K);
4421 }
4422 
4423 #ifdef ASSERT
4424 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4425   assert(ref != NULL, "invariant");
4426   assert(UseCompressedOops, "sanity");
4427   assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4428   oop p = oopDesc::load_decode_heap_oop(ref);
4429   assert(_g1h->is_in_g1_reserved(p),
4430          err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4431   return true;
4432 }
4433 
4434 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4435   assert(ref != NULL, "invariant");
4436   if (has_partial_array_mask(ref)) {
4437     // Must be in the collection set--it's already been copied.
4438     oop p = clear_partial_array_mask(ref);
4439     assert(_g1h->obj_in_cs(p),
4440            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4441   } else {
4442     oop p = oopDesc::load_decode_heap_oop(ref);
4443     assert(_g1h->is_in_g1_reserved(p),
4444            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4445   }
4446   return true;
4447 }
4448 
4449 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4450   if (ref.is_narrow()) {
4451     return verify_ref((narrowOop*) ref);
4452   } else {
4453     return verify_ref((oop*) ref);
4454   }
4455 }
4456 #endif // ASSERT
4457 
4458 void G1ParScanThreadState::trim_queue() {
4459   assert(_evac_cl != NULL, "not set");
4460   assert(_evac_failure_cl != NULL, "not set");
4461   assert(_partial_scan_cl != NULL, "not set");
4462 
4463   StarTask ref;
4464   do {
4465     // Drain the overflow stack first, so other threads can steal.
4466     while (refs()->pop_overflow(ref)) {
4467       deal_with_reference(ref);
4468     }
4469 
4470     while (refs()->pop_local(ref)) {
4471       deal_with_reference(ref);
4472     }
4473   } while (!refs()->is_empty());
4474 }
4475 
4476 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4477                                      G1ParScanThreadState* par_scan_state) :
4478   _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4479   _par_scan_state(par_scan_state),
4480   _worker_id(par_scan_state->queue_num()),
4481   _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4482   _mark_in_progress(_g1->mark_in_progress()) { }
4483 
4484 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4485 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4486 #ifdef ASSERT
4487   HeapRegion* hr = _g1->heap_region_containing(obj);
4488   assert(hr != NULL, "sanity");
4489   assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4490 #endif // ASSERT
4491 
4492   // We know that the object is not moving so it's safe to read its size.
4493   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4494 }
4495 
4496 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4497 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4498   ::mark_forwarded_object(oop from_obj, oop to_obj) {
4499 #ifdef ASSERT
4500   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4501   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4502   assert(from_obj != to_obj, "should not be self-forwarded");
4503 
4504   HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4505   assert(from_hr != NULL, "sanity");
4506   assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4507 
4508   HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4509   assert(to_hr != NULL, "sanity");
4510   assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4511 #endif // ASSERT
4512 
4513   // The object might be in the process of being copied by another
4514   // worker so we cannot trust that its to-space image is
4515   // well-formed. So we have to read its size from its from-space
4516   // image which we know should not be changing.
4517   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4518 }
4519 
4520 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4521 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4522   ::copy_to_survivor_space(oop old) {
4523   size_t word_sz = old->size();
4524   HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4525   // +1 to make the -1 indexes valid...
4526   int       young_index = from_region->young_index_in_cset()+1;
4527   assert( (from_region->is_young() && young_index >  0) ||
4528          (!from_region->is_young() && young_index == 0), "invariant" );
4529   G1CollectorPolicy* g1p = _g1->g1_policy();
4530   markOop m = old->mark();
4531   int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4532                                            : m->age();
4533   GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4534                                                              word_sz);
4535   HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4536 #ifndef PRODUCT
4537   // Should this evacuation fail?
4538   if (_g1->evacuation_should_fail()) {
4539     if (obj_ptr != NULL) {
4540       _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4541       obj_ptr = NULL;
4542     }
4543   }
4544 #endif // !PRODUCT
4545 
4546   if (obj_ptr == NULL) {
4547     // This will either forward-to-self, or detect that someone else has
4548     // installed a forwarding pointer.
4549     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4550     return _g1->handle_evacuation_failure_par(cl, old);
4551   }
4552 
4553   oop obj = oop(obj_ptr);
4554 
4555   // We're going to allocate linearly, so might as well prefetch ahead.
4556   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4557 
4558   oop forward_ptr = old->forward_to_atomic(obj);
4559   if (forward_ptr == NULL) {
4560     Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4561     if (g1p->track_object_age(alloc_purpose)) {
4562       // We could simply do obj->incr_age(). However, this causes a
4563       // performance issue. obj->incr_age() will first check whether
4564       // the object has a displaced mark by checking its mark word;
4565       // getting the mark word from the new location of the object
4566       // stalls. So, given that we already have the mark word and we
4567       // are about to install it anyway, it's better to increase the
4568       // age on the mark word, when the object does not have a
4569       // displaced mark word. We're not expecting many objects to have
4570       // a displaced marked word, so that case is not optimized
4571       // further (it could be...) and we simply call obj->incr_age().
4572 
4573       if (m->has_displaced_mark_helper()) {
4574         // in this case, we have to install the mark word first,
4575         // otherwise obj looks to be forwarded (the old mark word,
4576         // which contains the forward pointer, was copied)
4577         obj->set_mark(m);
4578         obj->incr_age();
4579       } else {
4580         m = m->incr_age();
4581         obj->set_mark(m);
4582       }
4583       _par_scan_state->age_table()->add(obj, word_sz);
4584     } else {
4585       obj->set_mark(m);
4586     }
4587 
4588     size_t* surv_young_words = _par_scan_state->surviving_young_words();
4589     surv_young_words[young_index] += word_sz;
4590 
4591     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4592       // We keep track of the next start index in the length field of
4593       // the to-space object. The actual length can be found in the
4594       // length field of the from-space object.
4595       arrayOop(obj)->set_length(0);
4596       oop* old_p = set_partial_array_mask(old);
4597       _par_scan_state->push_on_queue(old_p);
4598     } else {
4599       // No point in using the slower heap_region_containing() method,
4600       // given that we know obj is in the heap.
4601       _scanner.set_region(_g1->heap_region_containing_raw(obj));
4602       obj->oop_iterate_backwards(&_scanner);
4603     }
4604   } else {
4605     _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4606     obj = forward_ptr;
4607   }
4608   return obj;
4609 }
4610 
4611 template <class T>
4612 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4613   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4614     _scanned_klass->record_modified_oops();
4615   }
4616 }
4617 
4618 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4619 template <class T>
4620 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4621 ::do_oop_work(T* p) {
4622   oop obj = oopDesc::load_decode_heap_oop(p);
4623   assert(barrier != G1BarrierRS || obj != NULL,
4624          "Precondition: G1BarrierRS implies obj is non-NULL");
4625 
4626   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4627 
4628   // here the null check is implicit in the cset_fast_test() test
4629   if (_g1->in_cset_fast_test(obj)) {
4630     oop forwardee;
4631     if (obj->is_forwarded()) {
4632       forwardee = obj->forwardee();
4633     } else {
4634       forwardee = copy_to_survivor_space(obj);
4635     }
4636     assert(forwardee != NULL, "forwardee should not be NULL");
4637     oopDesc::encode_store_heap_oop(p, forwardee);
4638     if (do_mark_object && forwardee != obj) {
4639       // If the object is self-forwarded we don't need to explicitly
4640       // mark it, the evacuation failure protocol will do so.
4641       mark_forwarded_object(obj, forwardee);
4642     }
4643 
4644     // When scanning the RS, we only care about objs in CS.
4645     if (barrier == G1BarrierRS) {
4646       _par_scan_state->update_rs(_from, p, _worker_id);
4647     } else if (barrier == G1BarrierKlass) {
4648       do_klass_barrier(p, forwardee);
4649     }
4650   } else {
4651     // The object is not in collection set. If we're a root scanning
4652     // closure during an initial mark pause (i.e. do_mark_object will
4653     // be true) then attempt to mark the object.
4654     if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4655       mark_object(obj);
4656     }
4657   }
4658 
4659   if (barrier == G1BarrierEvac && obj != NULL) {
4660     _par_scan_state->update_rs(_from, p, _worker_id);
4661   }
4662 
4663   if (do_gen_barrier && obj != NULL) {
4664     par_do_barrier(p);
4665   }
4666 }
4667 
4668 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4669 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4670 
4671 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4672   assert(has_partial_array_mask(p), "invariant");
4673   oop from_obj = clear_partial_array_mask(p);
4674 
4675   assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4676   assert(from_obj->is_objArray(), "must be obj array");
4677   objArrayOop from_obj_array = objArrayOop(from_obj);
4678   // The from-space object contains the real length.
4679   int length                 = from_obj_array->length();
4680 
4681   assert(from_obj->is_forwarded(), "must be forwarded");
4682   oop to_obj                 = from_obj->forwardee();
4683   assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4684   objArrayOop to_obj_array   = objArrayOop(to_obj);
4685   // We keep track of the next start index in the length field of the
4686   // to-space object.
4687   int next_index             = to_obj_array->length();
4688   assert(0 <= next_index && next_index < length,
4689          err_msg("invariant, next index: %d, length: %d", next_index, length));
4690 
4691   int start                  = next_index;
4692   int end                    = length;
4693   int remainder              = end - start;
4694   // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4695   if (remainder > 2 * ParGCArrayScanChunk) {
4696     end = start + ParGCArrayScanChunk;
4697     to_obj_array->set_length(end);
4698     // Push the remainder before we process the range in case another
4699     // worker has run out of things to do and can steal it.
4700     oop* from_obj_p = set_partial_array_mask(from_obj);
4701     _par_scan_state->push_on_queue(from_obj_p);
4702   } else {
4703     assert(length == end, "sanity");
4704     // We'll process the final range for this object. Restore the length
4705     // so that the heap remains parsable in case of evacuation failure.
4706     to_obj_array->set_length(end);
4707   }
4708   _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4709   // Process indexes [start,end). It will also process the header
4710   // along with the first chunk (i.e., the chunk with start == 0).
4711   // Note that at this point the length field of to_obj_array is not
4712   // correct given that we are using it to keep track of the next
4713   // start index. oop_iterate_range() (thankfully!) ignores the length
4714   // field and only relies on the start / end parameters.  It does
4715   // however return the size of the object which will be incorrect. So
4716   // we have to ignore it even if we wanted to use it.
4717   to_obj_array->oop_iterate_range(&_scanner, start, end);
4718 }
4719 
4720 class G1ParEvacuateFollowersClosure : public VoidClosure {
4721 protected:
4722   G1CollectedHeap*              _g1h;
4723   G1ParScanThreadState*         _par_scan_state;
4724   RefToScanQueueSet*            _queues;
4725   ParallelTaskTerminator*       _terminator;
4726 
4727   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4728   RefToScanQueueSet*      queues()         { return _queues; }
4729   ParallelTaskTerminator* terminator()     { return _terminator; }
4730 
4731 public:
4732   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4733                                 G1ParScanThreadState* par_scan_state,
4734                                 RefToScanQueueSet* queues,
4735                                 ParallelTaskTerminator* terminator)
4736     : _g1h(g1h), _par_scan_state(par_scan_state),
4737       _queues(queues), _terminator(terminator) {}
4738 
4739   void do_void();
4740 
4741 private:
4742   inline bool offer_termination();
4743 };
4744 
4745 bool G1ParEvacuateFollowersClosure::offer_termination() {
4746   G1ParScanThreadState* const pss = par_scan_state();
4747   pss->start_term_time();
4748   const bool res = terminator()->offer_termination();
4749   pss->end_term_time();
4750   return res;
4751 }
4752 
4753 void G1ParEvacuateFollowersClosure::do_void() {
4754   StarTask stolen_task;
4755   G1ParScanThreadState* const pss = par_scan_state();
4756   pss->trim_queue();
4757 
4758   do {
4759     while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4760       assert(pss->verify_task(stolen_task), "sanity");
4761       if (stolen_task.is_narrow()) {
4762         pss->deal_with_reference((narrowOop*) stolen_task);
4763       } else {
4764         pss->deal_with_reference((oop*) stolen_task);
4765       }
4766 
4767       // We've just processed a reference and we might have made
4768       // available new entries on the queues. So we have to make sure
4769       // we drain the queues as necessary.
4770       pss->trim_queue();
4771     }
4772   } while (!offer_termination());
4773 
4774   pss->retire_alloc_buffers();
4775 }
4776 
4777 class G1KlassScanClosure : public KlassClosure {
4778  G1ParCopyHelper* _closure;
4779  bool             _process_only_dirty;
4780  int              _count;
4781  public:
4782   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4783       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4784   void do_klass(Klass* klass) {
4785     // If the klass has not been dirtied we know that there's
4786     // no references into  the young gen and we can skip it.
4787    if (!_process_only_dirty || klass->has_modified_oops()) {
4788       // Clean the klass since we're going to scavenge all the metadata.
4789       klass->clear_modified_oops();
4790 
4791       // Tell the closure that this klass is the Klass to scavenge
4792       // and is the one to dirty if oops are left pointing into the young gen.
4793       _closure->set_scanned_klass(klass);
4794 
4795       klass->oops_do(_closure);
4796 
4797       _closure->set_scanned_klass(NULL);
4798     }
4799     _count++;
4800   }
4801 };
4802 
4803 class G1ParTask : public AbstractGangTask {
4804 protected:
4805   G1CollectedHeap*       _g1h;
4806   RefToScanQueueSet      *_queues;
4807   ParallelTaskTerminator _terminator;
4808   uint _n_workers;
4809 
4810   Mutex _stats_lock;
4811   Mutex* stats_lock() { return &_stats_lock; }
4812 
4813   size_t getNCards() {
4814     return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4815       / G1BlockOffsetSharedArray::N_bytes;
4816   }
4817 
4818 public:
4819   G1ParTask(G1CollectedHeap* g1h,
4820             RefToScanQueueSet *task_queues)
4821     : AbstractGangTask("G1 collection"),
4822       _g1h(g1h),
4823       _queues(task_queues),
4824       _terminator(0, _queues),
4825       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4826   {}
4827 
4828   RefToScanQueueSet* queues() { return _queues; }
4829 
4830   RefToScanQueue *work_queue(int i) {
4831     return queues()->queue(i);
4832   }
4833 
4834   ParallelTaskTerminator* terminator() { return &_terminator; }
4835 
4836   virtual void set_for_termination(int active_workers) {
4837     // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4838     // in the young space (_par_seq_tasks) in the G1 heap
4839     // for SequentialSubTasksDone.
4840     // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4841     // both of which need setting by set_n_termination().
4842     _g1h->SharedHeap::set_n_termination(active_workers);
4843     _g1h->set_n_termination(active_workers);
4844     terminator()->reset_for_reuse(active_workers);
4845     _n_workers = active_workers;
4846   }
4847 
4848   void work(uint worker_id) {
4849     if (worker_id >= _n_workers) return;  // no work needed this round
4850 
4851     double start_time_ms = os::elapsedTime() * 1000.0;
4852     _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4853 
4854     {
4855       ResourceMark rm;
4856       HandleMark   hm;
4857 
4858       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4859 
4860       G1ParScanThreadState            pss(_g1h, worker_id);
4861       G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, rp);
4862       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4863       G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, rp);
4864 
4865       pss.set_evac_closure(&scan_evac_cl);
4866       pss.set_evac_failure_closure(&evac_failure_cl);
4867       pss.set_partial_scan_closure(&partial_scan_cl);
4868 
4869       G1ParScanExtRootClosure        only_scan_root_cl(_g1h, &pss, rp);
4870       G1ParScanMetadataClosure       only_scan_metadata_cl(_g1h, &pss, rp);
4871 
4872       G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4873       G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
4874 
4875       bool only_young                 = _g1h->g1_policy()->gcs_are_young();
4876       G1KlassScanClosure              scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
4877       G1KlassScanClosure              only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
4878 
4879       OopClosure*                    scan_root_cl = &only_scan_root_cl;
4880       G1KlassScanClosure*            scan_klasses_cl = &only_scan_klasses_cl_s;
4881 
4882       if (_g1h->g1_policy()->during_initial_mark_pause()) {
4883         // We also need to mark copied objects.
4884         scan_root_cl = &scan_mark_root_cl;
4885         scan_klasses_cl = &scan_mark_klasses_cl_s;
4886       }
4887 
4888       G1ParPushHeapRSClosure          push_heap_rs_cl(_g1h, &pss);
4889 
4890       int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
4891 
4892       pss.start_strong_roots();
4893       _g1h->g1_process_strong_roots(/* is scavenging */ true,
4894                                     SharedHeap::ScanningOption(so),
4895                                     scan_root_cl,
4896                                     &push_heap_rs_cl,
4897                                     scan_klasses_cl,
4898                                     worker_id);
4899       pss.end_strong_roots();
4900 
4901       {
4902         double start = os::elapsedTime();
4903         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4904         evac.do_void();
4905         double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4906         double term_ms = pss.term_time()*1000.0;
4907         _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4908         _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4909       }
4910       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4911       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4912 
4913       if (ParallelGCVerbose) {
4914         MutexLocker x(stats_lock());
4915         pss.print_termination_stats(worker_id);
4916       }
4917 
4918       assert(pss.refs()->is_empty(), "should be empty");
4919 
4920       // Close the inner scope so that the ResourceMark and HandleMark
4921       // destructors are executed here and are included as part of the
4922       // "GC Worker Time".
4923     }
4924 
4925     double end_time_ms = os::elapsedTime() * 1000.0;
4926     _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4927   }
4928 };
4929 
4930 // *** Common G1 Evacuation Stuff
4931 
4932 // Closures that support the filtering of CodeBlobs scanned during
4933 // external root scanning.
4934 
4935 // Closure applied to reference fields in code blobs (specifically nmethods)
4936 // to determine whether an nmethod contains references that point into
4937 // the collection set. Used as a predicate when walking code roots so
4938 // that only nmethods that point into the collection set are added to the
4939 // 'marked' list.
4940 
4941 class G1FilteredCodeBlobToOopClosure : public CodeBlobToOopClosure {
4942 
4943   class G1PointsIntoCSOopClosure : public OopClosure {
4944     G1CollectedHeap* _g1;
4945     bool _points_into_cs;
4946   public:
4947     G1PointsIntoCSOopClosure(G1CollectedHeap* g1) :
4948       _g1(g1), _points_into_cs(false) { }
4949 
4950     bool points_into_cs() const { return _points_into_cs; }
4951 
4952     template <class T>
4953     void do_oop_nv(T* p) {
4954       if (!_points_into_cs) {
4955         T heap_oop = oopDesc::load_heap_oop(p);
4956         if (!oopDesc::is_null(heap_oop) &&
4957             _g1->in_cset_fast_test(oopDesc::decode_heap_oop_not_null(heap_oop))) {
4958           _points_into_cs = true;
4959         }
4960       }
4961     }
4962 
4963     virtual void do_oop(oop* p)        { do_oop_nv(p); }
4964     virtual void do_oop(narrowOop* p)  { do_oop_nv(p); }
4965   };
4966 
4967   G1CollectedHeap* _g1;
4968 
4969 public:
4970   G1FilteredCodeBlobToOopClosure(G1CollectedHeap* g1, OopClosure* cl) :
4971     CodeBlobToOopClosure(cl, true), _g1(g1) { }
4972 
4973   virtual void do_code_blob(CodeBlob* cb) {
4974     nmethod* nm = cb->as_nmethod_or_null();
4975     if (nm != NULL && !(nm->test_oops_do_mark())) {
4976       G1PointsIntoCSOopClosure predicate_cl(_g1);
4977       nm->oops_do(&predicate_cl);
4978 
4979       if (predicate_cl.points_into_cs()) {
4980         // At least one of the reference fields or the oop relocations
4981         // in the nmethod points into the collection set. We have to
4982         // 'mark' this nmethod.
4983         // Note: Revisit the following if CodeBlobToOopClosure::do_code_blob()
4984         // or MarkingCodeBlobClosure::do_code_blob() change.
4985         if (!nm->test_set_oops_do_mark()) {
4986           do_newly_marked_nmethod(nm);
4987         }
4988       }
4989     }
4990   }
4991 };
4992 
4993 // This method is run in a GC worker.
4994 
4995 void
4996 G1CollectedHeap::
4997 g1_process_strong_roots(bool is_scavenging,
4998                         ScanningOption so,
4999                         OopClosure* scan_non_heap_roots,
5000                         OopsInHeapRegionClosure* scan_rs,
5001                         G1KlassScanClosure* scan_klasses,
5002                         int worker_i) {
5003 
5004   // First scan the strong roots
5005   double ext_roots_start = os::elapsedTime();
5006   double closure_app_time_sec = 0.0;
5007 
5008   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5009 
5010   // Walk the code cache w/o buffering, because StarTask cannot handle
5011   // unaligned oop locations.
5012   G1FilteredCodeBlobToOopClosure eager_scan_code_roots(this, scan_non_heap_roots);
5013 
5014   process_strong_roots(false, // no scoping; this is parallel code
5015                        is_scavenging, so,
5016                        &buf_scan_non_heap_roots,
5017                        &eager_scan_code_roots,
5018                        scan_klasses
5019                        );
5020 
5021   // Now the CM ref_processor roots.
5022   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5023     // We need to treat the discovered reference lists of the
5024     // concurrent mark ref processor as roots and keep entries
5025     // (which are added by the marking threads) on them live
5026     // until they can be processed at the end of marking.
5027     ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5028   }
5029 
5030   // Finish up any enqueued closure apps (attributed as object copy time).
5031   buf_scan_non_heap_roots.done();
5032 
5033   double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5034 
5035   g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5036 
5037   double ext_root_time_ms =
5038     ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5039 
5040   g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5041 
5042   // During conc marking we have to filter the per-thread SATB buffers
5043   // to make sure we remove any oops into the CSet (which will show up
5044   // as implicitly live).
5045   double satb_filtering_ms = 0.0;
5046   if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5047     if (mark_in_progress()) {
5048       double satb_filter_start = os::elapsedTime();
5049 
5050       JavaThread::satb_mark_queue_set().filter_thread_buffers();
5051 
5052       satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5053     }
5054   }
5055   g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5056 
5057   // Now scan the complement of the collection set.
5058   if (scan_rs != NULL) {
5059     g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
5060   }
5061   _process_strong_tasks->all_tasks_completed();
5062 }
5063 
5064 void
5065 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
5066                                        OopClosure* non_root_closure) {
5067   CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5068   SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
5069 }
5070 
5071 // Weak Reference Processing support
5072 
5073 // An always "is_alive" closure that is used to preserve referents.
5074 // If the object is non-null then it's alive.  Used in the preservation
5075 // of referent objects that are pointed to by reference objects
5076 // discovered by the CM ref processor.
5077 class G1AlwaysAliveClosure: public BoolObjectClosure {
5078   G1CollectedHeap* _g1;
5079 public:
5080   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5081   void do_object(oop p) { assert(false, "Do not call."); }
5082   bool do_object_b(oop p) {
5083     if (p != NULL) {
5084       return true;
5085     }
5086     return false;
5087   }
5088 };
5089 
5090 bool G1STWIsAliveClosure::do_object_b(oop p) {
5091   // An object is reachable if it is outside the collection set,
5092   // or is inside and copied.
5093   return !_g1->obj_in_cs(p) || p->is_forwarded();
5094 }
5095 
5096 // Non Copying Keep Alive closure
5097 class G1KeepAliveClosure: public OopClosure {
5098   G1CollectedHeap* _g1;
5099 public:
5100   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5101   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5102   void do_oop(      oop* p) {
5103     oop obj = *p;
5104 
5105     if (_g1->obj_in_cs(obj)) {
5106       assert( obj->is_forwarded(), "invariant" );
5107       *p = obj->forwardee();
5108     }
5109   }
5110 };
5111 
5112 // Copying Keep Alive closure - can be called from both
5113 // serial and parallel code as long as different worker
5114 // threads utilize different G1ParScanThreadState instances
5115 // and different queues.
5116 
5117 class G1CopyingKeepAliveClosure: public OopClosure {
5118   G1CollectedHeap*         _g1h;
5119   OopClosure*              _copy_non_heap_obj_cl;
5120   OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5121   G1ParScanThreadState*    _par_scan_state;
5122 
5123 public:
5124   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5125                             OopClosure* non_heap_obj_cl,
5126                             OopsInHeapRegionClosure* metadata_obj_cl,
5127                             G1ParScanThreadState* pss):
5128     _g1h(g1h),
5129     _copy_non_heap_obj_cl(non_heap_obj_cl),
5130     _copy_metadata_obj_cl(metadata_obj_cl),
5131     _par_scan_state(pss)
5132   {}
5133 
5134   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5135   virtual void do_oop(      oop* p) { do_oop_work(p); }
5136 
5137   template <class T> void do_oop_work(T* p) {
5138     oop obj = oopDesc::load_decode_heap_oop(p);
5139 
5140     if (_g1h->obj_in_cs(obj)) {
5141       // If the referent object has been forwarded (either copied
5142       // to a new location or to itself in the event of an
5143       // evacuation failure) then we need to update the reference
5144       // field and, if both reference and referent are in the G1
5145       // heap, update the RSet for the referent.
5146       //
5147       // If the referent has not been forwarded then we have to keep
5148       // it alive by policy. Therefore we have copy the referent.
5149       //
5150       // If the reference field is in the G1 heap then we can push
5151       // on the PSS queue. When the queue is drained (after each
5152       // phase of reference processing) the object and it's followers
5153       // will be copied, the reference field set to point to the
5154       // new location, and the RSet updated. Otherwise we need to
5155       // use the the non-heap or metadata closures directly to copy
5156       // the refernt object and update the pointer, while avoiding
5157       // updating the RSet.
5158 
5159       if (_g1h->is_in_g1_reserved(p)) {
5160         _par_scan_state->push_on_queue(p);
5161       } else {
5162         assert(!ClassLoaderDataGraph::contains((address)p),
5163                err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5164                               PTR_FORMAT, p));
5165           _copy_non_heap_obj_cl->do_oop(p);
5166         }
5167       }
5168     }
5169 };
5170 
5171 // Serial drain queue closure. Called as the 'complete_gc'
5172 // closure for each discovered list in some of the
5173 // reference processing phases.
5174 
5175 class G1STWDrainQueueClosure: public VoidClosure {
5176 protected:
5177   G1CollectedHeap* _g1h;
5178   G1ParScanThreadState* _par_scan_state;
5179 
5180   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5181 
5182 public:
5183   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5184     _g1h(g1h),
5185     _par_scan_state(pss)
5186   { }
5187 
5188   void do_void() {
5189     G1ParScanThreadState* const pss = par_scan_state();
5190     pss->trim_queue();
5191   }
5192 };
5193 
5194 // Parallel Reference Processing closures
5195 
5196 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5197 // processing during G1 evacuation pauses.
5198 
5199 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5200 private:
5201   G1CollectedHeap*   _g1h;
5202   RefToScanQueueSet* _queues;
5203   FlexibleWorkGang*  _workers;
5204   int                _active_workers;
5205 
5206 public:
5207   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5208                         FlexibleWorkGang* workers,
5209                         RefToScanQueueSet *task_queues,
5210                         int n_workers) :
5211     _g1h(g1h),
5212     _queues(task_queues),
5213     _workers(workers),
5214     _active_workers(n_workers)
5215   {
5216     assert(n_workers > 0, "shouldn't call this otherwise");
5217   }
5218 
5219   // Executes the given task using concurrent marking worker threads.
5220   virtual void execute(ProcessTask& task);
5221   virtual void execute(EnqueueTask& task);
5222 };
5223 
5224 // Gang task for possibly parallel reference processing
5225 
5226 class G1STWRefProcTaskProxy: public AbstractGangTask {
5227   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5228   ProcessTask&     _proc_task;
5229   G1CollectedHeap* _g1h;
5230   RefToScanQueueSet *_task_queues;
5231   ParallelTaskTerminator* _terminator;
5232 
5233 public:
5234   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5235                      G1CollectedHeap* g1h,
5236                      RefToScanQueueSet *task_queues,
5237                      ParallelTaskTerminator* terminator) :
5238     AbstractGangTask("Process reference objects in parallel"),
5239     _proc_task(proc_task),
5240     _g1h(g1h),
5241     _task_queues(task_queues),
5242     _terminator(terminator)
5243   {}
5244 
5245   virtual void work(uint worker_id) {
5246     // The reference processing task executed by a single worker.
5247     ResourceMark rm;
5248     HandleMark   hm;
5249 
5250     G1STWIsAliveClosure is_alive(_g1h);
5251 
5252     G1ParScanThreadState pss(_g1h, worker_id);
5253 
5254     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5255     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5256     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5257 
5258     pss.set_evac_closure(&scan_evac_cl);
5259     pss.set_evac_failure_closure(&evac_failure_cl);
5260     pss.set_partial_scan_closure(&partial_scan_cl);
5261 
5262     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5263     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5264 
5265     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5266     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5267 
5268     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5269     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5270 
5271     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5272       // We also need to mark copied objects.
5273       copy_non_heap_cl = &copy_mark_non_heap_cl;
5274       copy_metadata_cl = &copy_mark_metadata_cl;
5275     }
5276 
5277     // Keep alive closure.
5278     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5279 
5280     // Complete GC closure
5281     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5282 
5283     // Call the reference processing task's work routine.
5284     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5285 
5286     // Note we cannot assert that the refs array is empty here as not all
5287     // of the processing tasks (specifically phase2 - pp2_work) execute
5288     // the complete_gc closure (which ordinarily would drain the queue) so
5289     // the queue may not be empty.
5290   }
5291 };
5292 
5293 // Driver routine for parallel reference processing.
5294 // Creates an instance of the ref processing gang
5295 // task and has the worker threads execute it.
5296 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5297   assert(_workers != NULL, "Need parallel worker threads.");
5298 
5299   ParallelTaskTerminator terminator(_active_workers, _queues);
5300   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5301 
5302   _g1h->set_par_threads(_active_workers);
5303   _workers->run_task(&proc_task_proxy);
5304   _g1h->set_par_threads(0);
5305 }
5306 
5307 // Gang task for parallel reference enqueueing.
5308 
5309 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5310   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5311   EnqueueTask& _enq_task;
5312 
5313 public:
5314   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5315     AbstractGangTask("Enqueue reference objects in parallel"),
5316     _enq_task(enq_task)
5317   { }
5318 
5319   virtual void work(uint worker_id) {
5320     _enq_task.work(worker_id);
5321   }
5322 };
5323 
5324 // Driver routine for parallel reference enqueing.
5325 // Creates an instance of the ref enqueueing gang
5326 // task and has the worker threads execute it.
5327 
5328 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5329   assert(_workers != NULL, "Need parallel worker threads.");
5330 
5331   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5332 
5333   _g1h->set_par_threads(_active_workers);
5334   _workers->run_task(&enq_task_proxy);
5335   _g1h->set_par_threads(0);
5336 }
5337 
5338 // End of weak reference support closures
5339 
5340 // Abstract task used to preserve (i.e. copy) any referent objects
5341 // that are in the collection set and are pointed to by reference
5342 // objects discovered by the CM ref processor.
5343 
5344 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5345 protected:
5346   G1CollectedHeap* _g1h;
5347   RefToScanQueueSet      *_queues;
5348   ParallelTaskTerminator _terminator;
5349   uint _n_workers;
5350 
5351 public:
5352   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5353     AbstractGangTask("ParPreserveCMReferents"),
5354     _g1h(g1h),
5355     _queues(task_queues),
5356     _terminator(workers, _queues),
5357     _n_workers(workers)
5358   { }
5359 
5360   void work(uint worker_id) {
5361     ResourceMark rm;
5362     HandleMark   hm;
5363 
5364     G1ParScanThreadState            pss(_g1h, worker_id);
5365     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5366     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5367     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5368 
5369     pss.set_evac_closure(&scan_evac_cl);
5370     pss.set_evac_failure_closure(&evac_failure_cl);
5371     pss.set_partial_scan_closure(&partial_scan_cl);
5372 
5373     assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5374 
5375 
5376     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5377     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5378 
5379     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5380     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5381 
5382     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5383     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5384 
5385     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5386       // We also need to mark copied objects.
5387       copy_non_heap_cl = &copy_mark_non_heap_cl;
5388       copy_metadata_cl = &copy_mark_metadata_cl;
5389     }
5390 
5391     // Is alive closure
5392     G1AlwaysAliveClosure always_alive(_g1h);
5393 
5394     // Copying keep alive closure. Applied to referent objects that need
5395     // to be copied.
5396     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5397 
5398     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5399 
5400     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5401     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5402 
5403     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5404     // So this must be true - but assert just in case someone decides to
5405     // change the worker ids.
5406     assert(0 <= worker_id && worker_id < limit, "sanity");
5407     assert(!rp->discovery_is_atomic(), "check this code");
5408 
5409     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5410     for (uint idx = worker_id; idx < limit; idx += stride) {
5411       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5412 
5413       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5414       while (iter.has_next()) {
5415         // Since discovery is not atomic for the CM ref processor, we
5416         // can see some null referent objects.
5417         iter.load_ptrs(DEBUG_ONLY(true));
5418         oop ref = iter.obj();
5419 
5420         // This will filter nulls.
5421         if (iter.is_referent_alive()) {
5422           iter.make_referent_alive();
5423         }
5424         iter.move_to_next();
5425       }
5426     }
5427 
5428     // Drain the queue - which may cause stealing
5429     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5430     drain_queue.do_void();
5431     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5432     assert(pss.refs()->is_empty(), "should be");
5433   }
5434 };
5435 
5436 // Weak Reference processing during an evacuation pause (part 1).
5437 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5438   double ref_proc_start = os::elapsedTime();
5439 
5440   ReferenceProcessor* rp = _ref_processor_stw;
5441   assert(rp->discovery_enabled(), "should have been enabled");
5442 
5443   // Any reference objects, in the collection set, that were 'discovered'
5444   // by the CM ref processor should have already been copied (either by
5445   // applying the external root copy closure to the discovered lists, or
5446   // by following an RSet entry).
5447   //
5448   // But some of the referents, that are in the collection set, that these
5449   // reference objects point to may not have been copied: the STW ref
5450   // processor would have seen that the reference object had already
5451   // been 'discovered' and would have skipped discovering the reference,
5452   // but would not have treated the reference object as a regular oop.
5453   // As a reult the copy closure would not have been applied to the
5454   // referent object.
5455   //
5456   // We need to explicitly copy these referent objects - the references
5457   // will be processed at the end of remarking.
5458   //
5459   // We also need to do this copying before we process the reference
5460   // objects discovered by the STW ref processor in case one of these
5461   // referents points to another object which is also referenced by an
5462   // object discovered by the STW ref processor.
5463 
5464   assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5465            no_of_gc_workers == workers()->active_workers(),
5466            "Need to reset active GC workers");
5467 
5468   set_par_threads(no_of_gc_workers);
5469   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5470                                                  no_of_gc_workers,
5471                                                  _task_queues);
5472 
5473   if (G1CollectedHeap::use_parallel_gc_threads()) {
5474     workers()->run_task(&keep_cm_referents);
5475   } else {
5476     keep_cm_referents.work(0);
5477   }
5478 
5479   set_par_threads(0);
5480 
5481   // Closure to test whether a referent is alive.
5482   G1STWIsAliveClosure is_alive(this);
5483 
5484   // Even when parallel reference processing is enabled, the processing
5485   // of JNI refs is serial and performed serially by the current thread
5486   // rather than by a worker. The following PSS will be used for processing
5487   // JNI refs.
5488 
5489   // Use only a single queue for this PSS.
5490   G1ParScanThreadState pss(this, 0);
5491 
5492   // We do not embed a reference processor in the copying/scanning
5493   // closures while we're actually processing the discovered
5494   // reference objects.
5495   G1ParScanHeapEvacClosure        scan_evac_cl(this, &pss, NULL);
5496   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5497   G1ParScanPartialArrayClosure    partial_scan_cl(this, &pss, NULL);
5498 
5499   pss.set_evac_closure(&scan_evac_cl);
5500   pss.set_evac_failure_closure(&evac_failure_cl);
5501   pss.set_partial_scan_closure(&partial_scan_cl);
5502 
5503   assert(pss.refs()->is_empty(), "pre-condition");
5504 
5505   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5506   G1ParScanMetadataClosure       only_copy_metadata_cl(this, &pss, NULL);
5507 
5508   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5509   G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5510 
5511   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5512   OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5513 
5514   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5515     // We also need to mark copied objects.
5516     copy_non_heap_cl = &copy_mark_non_heap_cl;
5517     copy_metadata_cl = &copy_mark_metadata_cl;
5518   }
5519 
5520   // Keep alive closure.
5521   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5522 
5523   // Serial Complete GC closure
5524   G1STWDrainQueueClosure drain_queue(this, &pss);
5525 
5526   // Setup the soft refs policy...
5527   rp->setup_policy(false);
5528 
5529   if (!rp->processing_is_mt()) {
5530     // Serial reference processing...
5531     rp->process_discovered_references(&is_alive,
5532                                       &keep_alive,
5533                                       &drain_queue,
5534                                       NULL);
5535   } else {
5536     // Parallel reference processing
5537     assert(rp->num_q() == no_of_gc_workers, "sanity");
5538     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5539 
5540     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5541     rp->process_discovered_references(&is_alive, &keep_alive, &drain_queue, &par_task_executor);
5542   }
5543 
5544   // We have completed copying any necessary live referent objects
5545   // (that were not copied during the actual pause) so we can
5546   // retire any active alloc buffers
5547   pss.retire_alloc_buffers();
5548   assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5549 
5550   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5551   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5552 }
5553 
5554 // Weak Reference processing during an evacuation pause (part 2).
5555 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5556   double ref_enq_start = os::elapsedTime();
5557 
5558   ReferenceProcessor* rp = _ref_processor_stw;
5559   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5560 
5561   // Now enqueue any remaining on the discovered lists on to
5562   // the pending list.
5563   if (!rp->processing_is_mt()) {
5564     // Serial reference processing...
5565     rp->enqueue_discovered_references();
5566   } else {
5567     // Parallel reference enqueuing
5568 
5569     assert(no_of_gc_workers == workers()->active_workers(),
5570            "Need to reset active workers");
5571     assert(rp->num_q() == no_of_gc_workers, "sanity");
5572     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5573 
5574     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5575     rp->enqueue_discovered_references(&par_task_executor);
5576   }
5577 
5578   rp->verify_no_references_recorded();
5579   assert(!rp->discovery_enabled(), "should have been disabled");
5580 
5581   // FIXME
5582   // CM's reference processing also cleans up the string and symbol tables.
5583   // Should we do that here also? We could, but it is a serial operation
5584   // and could signicantly increase the pause time.
5585 
5586   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5587   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5588 }
5589 
5590 void G1CollectedHeap::evacuate_collection_set() {
5591   _expand_heap_after_alloc_failure = true;
5592   set_evacuation_failed(false);
5593 
5594   // Should G1EvacuationFailureALot be in effect for this GC?
5595   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5596 
5597   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5598   concurrent_g1_refine()->set_use_cache(false);
5599   concurrent_g1_refine()->clear_hot_cache_claimed_index();
5600 
5601   uint n_workers;
5602   if (G1CollectedHeap::use_parallel_gc_threads()) {
5603     n_workers =
5604       AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5605                                      workers()->active_workers(),
5606                                      Threads::number_of_non_daemon_threads());
5607     assert(UseDynamicNumberOfGCThreads ||
5608            n_workers == workers()->total_workers(),
5609            "If not dynamic should be using all the  workers");
5610     workers()->set_active_workers(n_workers);
5611     set_par_threads(n_workers);
5612   } else {
5613     assert(n_par_threads() == 0,
5614            "Should be the original non-parallel value");
5615     n_workers = 1;
5616   }
5617 
5618   G1ParTask g1_par_task(this, _task_queues);
5619 
5620   init_for_evac_failure(NULL);
5621 
5622   rem_set()->prepare_for_younger_refs_iterate(true);
5623 
5624   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5625   double start_par_time_sec = os::elapsedTime();
5626   double end_par_time_sec;
5627 
5628   {
5629     StrongRootsScope srs(this);
5630 
5631     if (G1CollectedHeap::use_parallel_gc_threads()) {
5632       // The individual threads will set their evac-failure closures.
5633       if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5634       // These tasks use ShareHeap::_process_strong_tasks
5635       assert(UseDynamicNumberOfGCThreads ||
5636              workers()->active_workers() == workers()->total_workers(),
5637              "If not dynamic should be using all the  workers");
5638       workers()->run_task(&g1_par_task);
5639     } else {
5640       g1_par_task.set_for_termination(n_workers);
5641       g1_par_task.work(0);
5642     }
5643     end_par_time_sec = os::elapsedTime();
5644 
5645     // Closing the inner scope will execute the destructor
5646     // for the StrongRootsScope object. We record the current
5647     // elapsed time before closing the scope so that time
5648     // taken for the SRS destructor is NOT included in the
5649     // reported parallel time.
5650   }
5651 
5652   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5653   g1_policy()->phase_times()->record_par_time(par_time_ms);
5654 
5655   double code_root_fixup_time_ms =
5656         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5657   g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5658 
5659   set_par_threads(0);
5660 
5661   // Process any discovered reference objects - we have
5662   // to do this _before_ we retire the GC alloc regions
5663   // as we may have to copy some 'reachable' referent
5664   // objects (and their reachable sub-graphs) that were
5665   // not copied during the pause.
5666   process_discovered_references(n_workers);
5667 
5668   // Weak root processing.
5669   // Note: when JSR 292 is enabled and code blobs can contain
5670   // non-perm oops then we will need to process the code blobs
5671   // here too.
5672   {
5673     G1STWIsAliveClosure is_alive(this);
5674     G1KeepAliveClosure keep_alive(this);
5675     JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5676   }
5677 
5678   release_gc_alloc_regions(n_workers);
5679   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5680 
5681   concurrent_g1_refine()->clear_hot_cache();
5682   concurrent_g1_refine()->set_use_cache(true);
5683 
5684   finalize_for_evac_failure();
5685 
5686   if (evacuation_failed()) {
5687     remove_self_forwarding_pointers();
5688 
5689     // Reset the G1EvacuationFailureALot counters and flags
5690     // Note: the values are reset only when an actual
5691     // evacuation failure occurs.
5692     NOT_PRODUCT(reset_evacuation_should_fail();)
5693   }
5694 
5695   // Enqueue any remaining references remaining on the STW
5696   // reference processor's discovered lists. We need to do
5697   // this after the card table is cleaned (and verified) as
5698   // the act of enqueuing entries on to the pending list
5699   // will log these updates (and dirty their associated
5700   // cards). We need these updates logged to update any
5701   // RSets.
5702   enqueue_discovered_references(n_workers);
5703 
5704   if (G1DeferredRSUpdate) {
5705     RedirtyLoggedCardTableEntryFastClosure redirty;
5706     dirty_card_queue_set().set_closure(&redirty);
5707     dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5708 
5709     DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5710     dcq.merge_bufferlists(&dirty_card_queue_set());
5711     assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5712   }
5713   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5714 }
5715 
5716 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5717                                      size_t* pre_used,
5718                                      FreeRegionList* free_list,
5719                                      OldRegionSet* old_proxy_set,
5720                                      HumongousRegionSet* humongous_proxy_set,
5721                                      HRRSCleanupTask* hrrs_cleanup_task,
5722                                      bool par) {
5723   if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5724     if (hr->isHumongous()) {
5725       assert(hr->startsHumongous(), "we should only see starts humongous");
5726       free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5727     } else {
5728       _old_set.remove_with_proxy(hr, old_proxy_set);
5729       free_region(hr, pre_used, free_list, par);
5730     }
5731   } else {
5732     hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5733   }
5734 }
5735 
5736 void G1CollectedHeap::free_region(HeapRegion* hr,
5737                                   size_t* pre_used,
5738                                   FreeRegionList* free_list,
5739                                   bool par) {
5740   assert(!hr->isHumongous(), "this is only for non-humongous regions");
5741   assert(!hr->is_empty(), "the region should not be empty");
5742   assert(free_list != NULL, "pre-condition");
5743 
5744   *pre_used += hr->used();
5745   hr->hr_clear(par, true /* clear_space */);
5746   free_list->add_as_head(hr);
5747 }
5748 
5749 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5750                                      size_t* pre_used,
5751                                      FreeRegionList* free_list,
5752                                      HumongousRegionSet* humongous_proxy_set,
5753                                      bool par) {
5754   assert(hr->startsHumongous(), "this is only for starts humongous regions");
5755   assert(free_list != NULL, "pre-condition");
5756   assert(humongous_proxy_set != NULL, "pre-condition");
5757 
5758   size_t hr_used = hr->used();
5759   size_t hr_capacity = hr->capacity();
5760   size_t hr_pre_used = 0;
5761   _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5762   // We need to read this before we make the region non-humongous,
5763   // otherwise the information will be gone.
5764   uint last_index = hr->last_hc_index();
5765   hr->set_notHumongous();
5766   free_region(hr, &hr_pre_used, free_list, par);
5767 
5768   uint i = hr->hrs_index() + 1;
5769   while (i < last_index) {
5770     HeapRegion* curr_hr = region_at(i);
5771     assert(curr_hr->continuesHumongous(), "invariant");
5772     curr_hr->set_notHumongous();
5773     free_region(curr_hr, &hr_pre_used, free_list, par);
5774     i += 1;
5775   }
5776   assert(hr_pre_used == hr_used,
5777          err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5778                  "should be the same", hr_pre_used, hr_used));
5779   *pre_used += hr_pre_used;
5780 }
5781 
5782 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5783                                        FreeRegionList* free_list,
5784                                        OldRegionSet* old_proxy_set,
5785                                        HumongousRegionSet* humongous_proxy_set,
5786                                        bool par) {
5787   if (pre_used > 0) {
5788     Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5789     MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5790     assert(_summary_bytes_used >= pre_used,
5791            err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5792                    "should be >= pre_used: "SIZE_FORMAT,
5793                    _summary_bytes_used, pre_used));
5794     _summary_bytes_used -= pre_used;
5795   }
5796   if (free_list != NULL && !free_list->is_empty()) {
5797     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5798     _free_list.add_as_head(free_list);
5799   }
5800   if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5801     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5802     _old_set.update_from_proxy(old_proxy_set);
5803   }
5804   if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5805     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5806     _humongous_set.update_from_proxy(humongous_proxy_set);
5807   }
5808 }
5809 
5810 class G1ParCleanupCTTask : public AbstractGangTask {
5811   CardTableModRefBS* _ct_bs;
5812   G1CollectedHeap* _g1h;
5813   HeapRegion* volatile _su_head;
5814 public:
5815   G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5816                      G1CollectedHeap* g1h) :
5817     AbstractGangTask("G1 Par Cleanup CT Task"),
5818     _ct_bs(ct_bs), _g1h(g1h) { }
5819 
5820   void work(uint worker_id) {
5821     HeapRegion* r;
5822     while (r = _g1h->pop_dirty_cards_region()) {
5823       clear_cards(r);
5824     }
5825   }
5826 
5827   void clear_cards(HeapRegion* r) {
5828     // Cards of the survivors should have already been dirtied.
5829     if (!r->is_survivor()) {
5830       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5831     }
5832   }
5833 };
5834 
5835 #ifndef PRODUCT
5836 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5837   G1CollectedHeap* _g1h;
5838   CardTableModRefBS* _ct_bs;
5839 public:
5840   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5841     : _g1h(g1h), _ct_bs(ct_bs) { }
5842   virtual bool doHeapRegion(HeapRegion* r) {
5843     if (r->is_survivor()) {
5844       _g1h->verify_dirty_region(r);
5845     } else {
5846       _g1h->verify_not_dirty_region(r);
5847     }
5848     return false;
5849   }
5850 };
5851 
5852 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5853   // All of the region should be clean.
5854   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5855   MemRegion mr(hr->bottom(), hr->end());
5856   ct_bs->verify_not_dirty_region(mr);
5857 }
5858 
5859 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5860   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5861   // dirty allocated blocks as they allocate them. The thread that
5862   // retires each region and replaces it with a new one will do a
5863   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5864   // not dirty that area (one less thing to have to do while holding
5865   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5866   // is dirty.
5867   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5868   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5869   ct_bs->verify_dirty_region(mr);
5870 }
5871 
5872 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5873   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5874   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5875     verify_dirty_region(hr);
5876   }
5877 }
5878 
5879 void G1CollectedHeap::verify_dirty_young_regions() {
5880   verify_dirty_young_list(_young_list->first_region());
5881 }
5882 #endif
5883 
5884 void G1CollectedHeap::cleanUpCardTable() {
5885   CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5886   double start = os::elapsedTime();
5887 
5888   {
5889     // Iterate over the dirty cards region list.
5890     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5891 
5892     if (G1CollectedHeap::use_parallel_gc_threads()) {
5893       set_par_threads();
5894       workers()->run_task(&cleanup_task);
5895       set_par_threads(0);
5896     } else {
5897       while (_dirty_cards_region_list) {
5898         HeapRegion* r = _dirty_cards_region_list;
5899         cleanup_task.clear_cards(r);
5900         _dirty_cards_region_list = r->get_next_dirty_cards_region();
5901         if (_dirty_cards_region_list == r) {
5902           // The last region.
5903           _dirty_cards_region_list = NULL;
5904         }
5905         r->set_next_dirty_cards_region(NULL);
5906       }
5907     }
5908 #ifndef PRODUCT
5909     if (G1VerifyCTCleanup || VerifyAfterGC) {
5910       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5911       heap_region_iterate(&cleanup_verifier);
5912     }
5913 #endif
5914   }
5915 
5916   double elapsed = os::elapsedTime() - start;
5917   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5918 }
5919 
5920 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
5921   size_t pre_used = 0;
5922   FreeRegionList local_free_list("Local List for CSet Freeing");
5923 
5924   double young_time_ms     = 0.0;
5925   double non_young_time_ms = 0.0;
5926 
5927   // Since the collection set is a superset of the the young list,
5928   // all we need to do to clear the young list is clear its
5929   // head and length, and unlink any young regions in the code below
5930   _young_list->clear();
5931 
5932   G1CollectorPolicy* policy = g1_policy();
5933 
5934   double start_sec = os::elapsedTime();
5935   bool non_young = true;
5936 
5937   HeapRegion* cur = cs_head;
5938   int age_bound = -1;
5939   size_t rs_lengths = 0;
5940 
5941   while (cur != NULL) {
5942     assert(!is_on_master_free_list(cur), "sanity");
5943     if (non_young) {
5944       if (cur->is_young()) {
5945         double end_sec = os::elapsedTime();
5946         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5947         non_young_time_ms += elapsed_ms;
5948 
5949         start_sec = os::elapsedTime();
5950         non_young = false;
5951       }
5952     } else {
5953       if (!cur->is_young()) {
5954         double end_sec = os::elapsedTime();
5955         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5956         young_time_ms += elapsed_ms;
5957 
5958         start_sec = os::elapsedTime();
5959         non_young = true;
5960       }
5961     }
5962 
5963     rs_lengths += cur->rem_set()->occupied();
5964 
5965     HeapRegion* next = cur->next_in_collection_set();
5966     assert(cur->in_collection_set(), "bad CS");
5967     cur->set_next_in_collection_set(NULL);
5968     cur->set_in_collection_set(false);
5969 
5970     if (cur->is_young()) {
5971       int index = cur->young_index_in_cset();
5972       assert(index != -1, "invariant");
5973       assert((uint) index < policy->young_cset_region_length(), "invariant");
5974       size_t words_survived = _surviving_young_words[index];
5975       cur->record_surv_words_in_group(words_survived);
5976 
5977       // At this point the we have 'popped' cur from the collection set
5978       // (linked via next_in_collection_set()) but it is still in the
5979       // young list (linked via next_young_region()). Clear the
5980       // _next_young_region field.
5981       cur->set_next_young_region(NULL);
5982     } else {
5983       int index = cur->young_index_in_cset();
5984       assert(index == -1, "invariant");
5985     }
5986 
5987     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5988             (!cur->is_young() && cur->young_index_in_cset() == -1),
5989             "invariant" );
5990 
5991     if (!cur->evacuation_failed()) {
5992       MemRegion used_mr = cur->used_region();
5993 
5994       // And the region is empty.
5995       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5996       free_region(cur, &pre_used, &local_free_list, false /* par */);
5997     } else {
5998       cur->uninstall_surv_rate_group();
5999       if (cur->is_young()) {
6000         cur->set_young_index_in_cset(-1);
6001       }
6002       cur->set_not_young();
6003       cur->set_evacuation_failed(false);
6004       // The region is now considered to be old.
6005       _old_set.add(cur);
6006     }
6007     cur = next;
6008   }
6009 
6010   policy->record_max_rs_lengths(rs_lengths);
6011   policy->cset_regions_freed();
6012 
6013   double end_sec = os::elapsedTime();
6014   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6015 
6016   if (non_young) {
6017     non_young_time_ms += elapsed_ms;
6018   } else {
6019     young_time_ms += elapsed_ms;
6020   }
6021 
6022   update_sets_after_freeing_regions(pre_used, &local_free_list,
6023                                     NULL /* old_proxy_set */,
6024                                     NULL /* humongous_proxy_set */,
6025                                     false /* par */);
6026   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6027   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6028 }
6029 
6030 // This routine is similar to the above but does not record
6031 // any policy statistics or update free lists; we are abandoning
6032 // the current incremental collection set in preparation of a
6033 // full collection. After the full GC we will start to build up
6034 // the incremental collection set again.
6035 // This is only called when we're doing a full collection
6036 // and is immediately followed by the tearing down of the young list.
6037 
6038 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6039   HeapRegion* cur = cs_head;
6040 
6041   while (cur != NULL) {
6042     HeapRegion* next = cur->next_in_collection_set();
6043     assert(cur->in_collection_set(), "bad CS");
6044     cur->set_next_in_collection_set(NULL);
6045     cur->set_in_collection_set(false);
6046     cur->set_young_index_in_cset(-1);
6047     cur = next;
6048   }
6049 }
6050 
6051 void G1CollectedHeap::set_free_regions_coming() {
6052   if (G1ConcRegionFreeingVerbose) {
6053     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6054                            "setting free regions coming");
6055   }
6056 
6057   assert(!free_regions_coming(), "pre-condition");
6058   _free_regions_coming = true;
6059 }
6060 
6061 void G1CollectedHeap::reset_free_regions_coming() {
6062   assert(free_regions_coming(), "pre-condition");
6063 
6064   {
6065     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6066     _free_regions_coming = false;
6067     SecondaryFreeList_lock->notify_all();
6068   }
6069 
6070   if (G1ConcRegionFreeingVerbose) {
6071     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6072                            "reset free regions coming");
6073   }
6074 }
6075 
6076 void G1CollectedHeap::wait_while_free_regions_coming() {
6077   // Most of the time we won't have to wait, so let's do a quick test
6078   // first before we take the lock.
6079   if (!free_regions_coming()) {
6080     return;
6081   }
6082 
6083   if (G1ConcRegionFreeingVerbose) {
6084     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6085                            "waiting for free regions");
6086   }
6087 
6088   {
6089     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6090     while (free_regions_coming()) {
6091       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6092     }
6093   }
6094 
6095   if (G1ConcRegionFreeingVerbose) {
6096     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6097                            "done waiting for free regions");
6098   }
6099 }
6100 
6101 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6102   assert(heap_lock_held_for_gc(),
6103               "the heap lock should already be held by or for this thread");
6104   _young_list->push_region(hr);
6105 }
6106 
6107 class NoYoungRegionsClosure: public HeapRegionClosure {
6108 private:
6109   bool _success;
6110 public:
6111   NoYoungRegionsClosure() : _success(true) { }
6112   bool doHeapRegion(HeapRegion* r) {
6113     if (r->is_young()) {
6114       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6115                              r->bottom(), r->end());
6116       _success = false;
6117     }
6118     return false;
6119   }
6120   bool success() { return _success; }
6121 };
6122 
6123 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6124   bool ret = _young_list->check_list_empty(check_sample);
6125 
6126   if (check_heap) {
6127     NoYoungRegionsClosure closure;
6128     heap_region_iterate(&closure);
6129     ret = ret && closure.success();
6130   }
6131 
6132   return ret;
6133 }
6134 
6135 class TearDownRegionSetsClosure : public HeapRegionClosure {
6136 private:
6137   OldRegionSet *_old_set;
6138 
6139 public:
6140   TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6141 
6142   bool doHeapRegion(HeapRegion* r) {
6143     if (r->is_empty()) {
6144       // We ignore empty regions, we'll empty the free list afterwards
6145     } else if (r->is_young()) {
6146       // We ignore young regions, we'll empty the young list afterwards
6147     } else if (r->isHumongous()) {
6148       // We ignore humongous regions, we're not tearing down the
6149       // humongous region set
6150     } else {
6151       // The rest should be old
6152       _old_set->remove(r);
6153     }
6154     return false;
6155   }
6156 
6157   ~TearDownRegionSetsClosure() {
6158     assert(_old_set->is_empty(), "post-condition");
6159   }
6160 };
6161 
6162 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6163   assert_at_safepoint(true /* should_be_vm_thread */);
6164 
6165   if (!free_list_only) {
6166     TearDownRegionSetsClosure cl(&_old_set);
6167     heap_region_iterate(&cl);
6168 
6169     // Need to do this after the heap iteration to be able to
6170     // recognize the young regions and ignore them during the iteration.
6171     _young_list->empty_list();
6172   }
6173   _free_list.remove_all();
6174 }
6175 
6176 class RebuildRegionSetsClosure : public HeapRegionClosure {
6177 private:
6178   bool            _free_list_only;
6179   OldRegionSet*   _old_set;
6180   FreeRegionList* _free_list;
6181   size_t          _total_used;
6182 
6183 public:
6184   RebuildRegionSetsClosure(bool free_list_only,
6185                            OldRegionSet* old_set, FreeRegionList* free_list) :
6186     _free_list_only(free_list_only),
6187     _old_set(old_set), _free_list(free_list), _total_used(0) {
6188     assert(_free_list->is_empty(), "pre-condition");
6189     if (!free_list_only) {
6190       assert(_old_set->is_empty(), "pre-condition");
6191     }
6192   }
6193 
6194   bool doHeapRegion(HeapRegion* r) {
6195     if (r->continuesHumongous()) {
6196       return false;
6197     }
6198 
6199     if (r->is_empty()) {
6200       // Add free regions to the free list
6201       _free_list->add_as_tail(r);
6202     } else if (!_free_list_only) {
6203       assert(!r->is_young(), "we should not come across young regions");
6204 
6205       if (r->isHumongous()) {
6206         // We ignore humongous regions, we left the humongous set unchanged
6207       } else {
6208         // The rest should be old, add them to the old set
6209         _old_set->add(r);
6210       }
6211       _total_used += r->used();
6212     }
6213 
6214     return false;
6215   }
6216 
6217   size_t total_used() {
6218     return _total_used;
6219   }
6220 };
6221 
6222 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6223   assert_at_safepoint(true /* should_be_vm_thread */);
6224 
6225   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6226   heap_region_iterate(&cl);
6227 
6228   if (!free_list_only) {
6229     _summary_bytes_used = cl.total_used();
6230   }
6231   assert(_summary_bytes_used == recalculate_used(),
6232          err_msg("inconsistent _summary_bytes_used, "
6233                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6234                  _summary_bytes_used, recalculate_used()));
6235 }
6236 
6237 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6238   _refine_cte_cl->set_concurrent(concurrent);
6239 }
6240 
6241 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6242   HeapRegion* hr = heap_region_containing(p);
6243   if (hr == NULL) {
6244     return false;
6245   } else {
6246     return hr->is_in(p);
6247   }
6248 }
6249 
6250 // Methods for the mutator alloc region
6251 
6252 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6253                                                       bool force) {
6254   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6255   assert(!force || g1_policy()->can_expand_young_list(),
6256          "if force is true we should be able to expand the young list");
6257   bool young_list_full = g1_policy()->is_young_list_full();
6258   if (force || !young_list_full) {
6259     HeapRegion* new_alloc_region = new_region(word_size,
6260                                               false /* do_expand */);
6261     if (new_alloc_region != NULL) {
6262       set_region_short_lived_locked(new_alloc_region);
6263       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6264       return new_alloc_region;
6265     }
6266   }
6267   return NULL;
6268 }
6269 
6270 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6271                                                   size_t allocated_bytes) {
6272   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6273   assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6274 
6275   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6276   _summary_bytes_used += allocated_bytes;
6277   _hr_printer.retire(alloc_region);
6278   // We update the eden sizes here, when the region is retired,
6279   // instead of when it's allocated, since this is the point that its
6280   // used space has been recored in _summary_bytes_used.
6281   g1mm()->update_eden_size();
6282 }
6283 
6284 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6285                                                     bool force) {
6286   return _g1h->new_mutator_alloc_region(word_size, force);
6287 }
6288 
6289 void G1CollectedHeap::set_par_threads() {
6290   // Don't change the number of workers.  Use the value previously set
6291   // in the workgroup.
6292   assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6293   uint n_workers = workers()->active_workers();
6294   assert(UseDynamicNumberOfGCThreads ||
6295            n_workers == workers()->total_workers(),
6296       "Otherwise should be using the total number of workers");
6297   if (n_workers == 0) {
6298     assert(false, "Should have been set in prior evacuation pause.");
6299     n_workers = ParallelGCThreads;
6300     workers()->set_active_workers(n_workers);
6301   }
6302   set_par_threads(n_workers);
6303 }
6304 
6305 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6306                                        size_t allocated_bytes) {
6307   _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6308 }
6309 
6310 // Methods for the GC alloc regions
6311 
6312 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6313                                                  uint count,
6314                                                  GCAllocPurpose ap) {
6315   assert(FreeList_lock->owned_by_self(), "pre-condition");
6316 
6317   if (count < g1_policy()->max_regions(ap)) {
6318     HeapRegion* new_alloc_region = new_region(word_size,
6319                                               true /* do_expand */);
6320     if (new_alloc_region != NULL) {
6321       // We really only need to do this for old regions given that we
6322       // should never scan survivors. But it doesn't hurt to do it
6323       // for survivors too.
6324       new_alloc_region->set_saved_mark();
6325       if (ap == GCAllocForSurvived) {
6326         new_alloc_region->set_survivor();
6327         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6328       } else {
6329         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6330       }
6331       bool during_im = g1_policy()->during_initial_mark_pause();
6332       new_alloc_region->note_start_of_copying(during_im);
6333       return new_alloc_region;
6334     } else {
6335       g1_policy()->note_alloc_region_limit_reached(ap);
6336     }
6337   }
6338   return NULL;
6339 }
6340 
6341 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6342                                              size_t allocated_bytes,
6343                                              GCAllocPurpose ap) {
6344   bool during_im = g1_policy()->during_initial_mark_pause();
6345   alloc_region->note_end_of_copying(during_im);
6346   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6347   if (ap == GCAllocForSurvived) {
6348     young_list()->add_survivor_region(alloc_region);
6349   } else {
6350     _old_set.add(alloc_region);
6351   }
6352   _hr_printer.retire(alloc_region);
6353 }
6354 
6355 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6356                                                        bool force) {
6357   assert(!force, "not supported for GC alloc regions");
6358   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6359 }
6360 
6361 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6362                                           size_t allocated_bytes) {
6363   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6364                                GCAllocForSurvived);
6365 }
6366 
6367 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6368                                                   bool force) {
6369   assert(!force, "not supported for GC alloc regions");
6370   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6371 }
6372 
6373 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6374                                      size_t allocated_bytes) {
6375   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6376                                GCAllocForTenured);
6377 }
6378 // Heap region set verification
6379 
6380 class VerifyRegionListsClosure : public HeapRegionClosure {
6381 private:
6382   FreeRegionList*     _free_list;
6383   OldRegionSet*       _old_set;
6384   HumongousRegionSet* _humongous_set;
6385   uint                _region_count;
6386 
6387 public:
6388   VerifyRegionListsClosure(OldRegionSet* old_set,
6389                            HumongousRegionSet* humongous_set,
6390                            FreeRegionList* free_list) :
6391     _old_set(old_set), _humongous_set(humongous_set),
6392     _free_list(free_list), _region_count(0) { }
6393 
6394   uint region_count() { return _region_count; }
6395 
6396   bool doHeapRegion(HeapRegion* hr) {
6397     _region_count += 1;
6398 
6399     if (hr->continuesHumongous()) {
6400       return false;
6401     }
6402 
6403     if (hr->is_young()) {
6404       // TODO
6405     } else if (hr->startsHumongous()) {
6406       _humongous_set->verify_next_region(hr);
6407     } else if (hr->is_empty()) {
6408       _free_list->verify_next_region(hr);
6409     } else {
6410       _old_set->verify_next_region(hr);
6411     }
6412     return false;
6413   }
6414 };
6415 
6416 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6417                                              HeapWord* bottom) {
6418   HeapWord* end = bottom + HeapRegion::GrainWords;
6419   MemRegion mr(bottom, end);
6420   assert(_g1_reserved.contains(mr), "invariant");
6421   // This might return NULL if the allocation fails
6422   return new HeapRegion(hrs_index, _bot_shared, mr);
6423 }
6424 
6425 void G1CollectedHeap::verify_region_sets() {
6426   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6427 
6428   // First, check the explicit lists.
6429   _free_list.verify();
6430   {
6431     // Given that a concurrent operation might be adding regions to
6432     // the secondary free list we have to take the lock before
6433     // verifying it.
6434     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6435     _secondary_free_list.verify();
6436   }
6437   _old_set.verify();
6438   _humongous_set.verify();
6439 
6440   // If a concurrent region freeing operation is in progress it will
6441   // be difficult to correctly attributed any free regions we come
6442   // across to the correct free list given that they might belong to
6443   // one of several (free_list, secondary_free_list, any local lists,
6444   // etc.). So, if that's the case we will skip the rest of the
6445   // verification operation. Alternatively, waiting for the concurrent
6446   // operation to complete will have a non-trivial effect on the GC's
6447   // operation (no concurrent operation will last longer than the
6448   // interval between two calls to verification) and it might hide
6449   // any issues that we would like to catch during testing.
6450   if (free_regions_coming()) {
6451     return;
6452   }
6453 
6454   // Make sure we append the secondary_free_list on the free_list so
6455   // that all free regions we will come across can be safely
6456   // attributed to the free_list.
6457   append_secondary_free_list_if_not_empty_with_lock();
6458 
6459   // Finally, make sure that the region accounting in the lists is
6460   // consistent with what we see in the heap.
6461   _old_set.verify_start();
6462   _humongous_set.verify_start();
6463   _free_list.verify_start();
6464 
6465   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6466   heap_region_iterate(&cl);
6467 
6468   _old_set.verify_end();
6469   _humongous_set.verify_end();
6470   _free_list.verify_end();
6471 }
--- EOF ---