1 /*
   2  * Copyright (c) 2001, 2011, 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/g1MarkSweep.hpp"
  36 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
  37 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  38 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  39 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
  40 #include "gc_implementation/g1/vm_operations_g1.hpp"
  41 #include "gc_implementation/shared/isGCActiveMark.hpp"
  42 #include "memory/gcLocker.inline.hpp"
  43 #include "memory/genOopClosures.inline.hpp"
  44 #include "memory/generationSpec.hpp"
  45 #include "memory/referenceProcessor.hpp"
  46 #include "oops/oop.inline.hpp"
  47 #include "oops/oop.pcgc.inline.hpp"
  48 #include "runtime/aprofiler.hpp"
  49 #include "runtime/vmThread.hpp"
  50 
  51 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  52 
  53 // turn it on so that the contents of the young list (scan-only /
  54 // to-be-collected) are printed at "strategic" points before / during
  55 // / after the collection --- this is useful for debugging
  56 #define YOUNG_LIST_VERBOSE 0
  57 // CURRENT STATUS
  58 // This file is under construction.  Search for "FIXME".
  59 
  60 // INVARIANTS/NOTES
  61 //
  62 // All allocation activity covered by the G1CollectedHeap interface is
  63 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  64 // and allocate_new_tlab, which are the "entry" points to the
  65 // allocation code from the rest of the JVM.  (Note that this does not
  66 // apply to TLAB allocation, which is not part of this interface: it
  67 // is done by clients of this interface.)
  68 
  69 // Notes on implementation of parallelism in different tasks.
  70 //
  71 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
  72 // The number of GC workers is passed to heap_region_par_iterate_chunked().
  73 // It does use run_task() which sets _n_workers in the task.
  74 // G1ParTask executes g1_process_strong_roots() ->
  75 // SharedHeap::process_strong_roots() which calls eventuall to
  76 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
  77 // SequentialSubTasksDone.  SharedHeap::process_strong_roots() also
  78 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
  79 //
  80 
  81 // Local to this file.
  82 
  83 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  84   SuspendibleThreadSet* _sts;
  85   G1RemSet* _g1rs;
  86   ConcurrentG1Refine* _cg1r;
  87   bool _concurrent;
  88 public:
  89   RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
  90                               G1RemSet* g1rs,
  91                               ConcurrentG1Refine* cg1r) :
  92     _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
  93   {}
  94   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
  95     bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
  96     // This path is executed by the concurrent refine or mutator threads,
  97     // concurrently, and so we do not care if card_ptr contains references
  98     // that point into the collection set.
  99     assert(!oops_into_cset, "should be");
 100 
 101     if (_concurrent && _sts->should_yield()) {
 102       // Caller will actually yield.
 103       return false;
 104     }
 105     // Otherwise, we finished successfully; return true.
 106     return true;
 107   }
 108   void set_concurrent(bool b) { _concurrent = b; }
 109 };
 110 
 111 
 112 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
 113   int _calls;
 114   G1CollectedHeap* _g1h;
 115   CardTableModRefBS* _ctbs;
 116   int _histo[256];
 117 public:
 118   ClearLoggedCardTableEntryClosure() :
 119     _calls(0)
 120   {
 121     _g1h = G1CollectedHeap::heap();
 122     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
 123     for (int i = 0; i < 256; i++) _histo[i] = 0;
 124   }
 125   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 126     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 127       _calls++;
 128       unsigned char* ujb = (unsigned char*)card_ptr;
 129       int ind = (int)(*ujb);
 130       _histo[ind]++;
 131       *card_ptr = -1;
 132     }
 133     return true;
 134   }
 135   int calls() { return _calls; }
 136   void print_histo() {
 137     gclog_or_tty->print_cr("Card table value histogram:");
 138     for (int i = 0; i < 256; i++) {
 139       if (_histo[i] != 0) {
 140         gclog_or_tty->print_cr("  %d: %d", i, _histo[i]);
 141       }
 142     }
 143   }
 144 };
 145 
 146 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
 147   int _calls;
 148   G1CollectedHeap* _g1h;
 149   CardTableModRefBS* _ctbs;
 150 public:
 151   RedirtyLoggedCardTableEntryClosure() :
 152     _calls(0)
 153   {
 154     _g1h = G1CollectedHeap::heap();
 155     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
 156   }
 157   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 158     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
 159       _calls++;
 160       *card_ptr = 0;
 161     }
 162     return true;
 163   }
 164   int calls() { return _calls; }
 165 };
 166 
 167 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
 168 public:
 169   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
 170     *card_ptr = CardTableModRefBS::dirty_card_val();
 171     return true;
 172   }
 173 };
 174 
 175 YoungList::YoungList(G1CollectedHeap* g1h)
 176   : _g1h(g1h), _head(NULL),
 177     _length(0),
 178     _last_sampled_rs_lengths(0),
 179     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
 180 {
 181   guarantee( check_list_empty(false), "just making sure..." );
 182 }
 183 
 184 void YoungList::push_region(HeapRegion *hr) {
 185   assert(!hr->is_young(), "should not already be young");
 186   assert(hr->get_next_young_region() == NULL, "cause it should!");
 187 
 188   hr->set_next_young_region(_head);
 189   _head = hr;
 190 
 191   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 192   ++_length;
 193 }
 194 
 195 void YoungList::add_survivor_region(HeapRegion* hr) {
 196   assert(hr->is_survivor(), "should be flagged as survivor region");
 197   assert(hr->get_next_young_region() == NULL, "cause it should!");
 198 
 199   hr->set_next_young_region(_survivor_head);
 200   if (_survivor_head == NULL) {
 201     _survivor_tail = hr;
 202   }
 203   _survivor_head = hr;
 204   ++_survivor_length;
 205 }
 206 
 207 void YoungList::empty_list(HeapRegion* list) {
 208   while (list != NULL) {
 209     HeapRegion* next = list->get_next_young_region();
 210     list->set_next_young_region(NULL);
 211     list->uninstall_surv_rate_group();
 212     list->set_not_young();
 213     list = next;
 214   }
 215 }
 216 
 217 void YoungList::empty_list() {
 218   assert(check_list_well_formed(), "young list should be well formed");
 219 
 220   empty_list(_head);
 221   _head = NULL;
 222   _length = 0;
 223 
 224   empty_list(_survivor_head);
 225   _survivor_head = NULL;
 226   _survivor_tail = NULL;
 227   _survivor_length = 0;
 228 
 229   _last_sampled_rs_lengths = 0;
 230 
 231   assert(check_list_empty(false), "just making sure...");
 232 }
 233 
 234 bool YoungList::check_list_well_formed() {
 235   bool ret = true;
 236 
 237   size_t length = 0;
 238   HeapRegion* curr = _head;
 239   HeapRegion* last = NULL;
 240   while (curr != NULL) {
 241     if (!curr->is_young()) {
 242       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 243                              "incorrectly tagged (y: %d, surv: %d)",
 244                              curr->bottom(), curr->end(),
 245                              curr->is_young(), curr->is_survivor());
 246       ret = false;
 247     }
 248     ++length;
 249     last = curr;
 250     curr = curr->get_next_young_region();
 251   }
 252   ret = ret && (length == _length);
 253 
 254   if (!ret) {
 255     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 256     gclog_or_tty->print_cr("###   list has %d entries, _length is %d",
 257                            length, _length);
 258   }
 259 
 260   return ret;
 261 }
 262 
 263 bool YoungList::check_list_empty(bool check_sample) {
 264   bool ret = true;
 265 
 266   if (_length != 0) {
 267     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
 268                   _length);
 269     ret = false;
 270   }
 271   if (check_sample && _last_sampled_rs_lengths != 0) {
 272     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 273     ret = false;
 274   }
 275   if (_head != NULL) {
 276     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 277     ret = false;
 278   }
 279   if (!ret) {
 280     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 281   }
 282 
 283   return ret;
 284 }
 285 
 286 void
 287 YoungList::rs_length_sampling_init() {
 288   _sampled_rs_lengths = 0;
 289   _curr               = _head;
 290 }
 291 
 292 bool
 293 YoungList::rs_length_sampling_more() {
 294   return _curr != NULL;
 295 }
 296 
 297 void
 298 YoungList::rs_length_sampling_next() {
 299   assert( _curr != NULL, "invariant" );
 300   size_t rs_length = _curr->rem_set()->occupied();
 301 
 302   _sampled_rs_lengths += rs_length;
 303 
 304   // The current region may not yet have been added to the
 305   // incremental collection set (it gets added when it is
 306   // retired as the current allocation region).
 307   if (_curr->in_collection_set()) {
 308     // Update the collection set policy information for this region
 309     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 310   }
 311 
 312   _curr = _curr->get_next_young_region();
 313   if (_curr == NULL) {
 314     _last_sampled_rs_lengths = _sampled_rs_lengths;
 315     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 316   }
 317 }
 318 
 319 void
 320 YoungList::reset_auxilary_lists() {
 321   guarantee( is_empty(), "young list should be empty" );
 322   assert(check_list_well_formed(), "young list should be well formed");
 323 
 324   // Add survivor regions to SurvRateGroup.
 325   _g1h->g1_policy()->note_start_adding_survivor_regions();
 326   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 327 
 328   int young_index_in_cset = 0;
 329   for (HeapRegion* curr = _survivor_head;
 330        curr != NULL;
 331        curr = curr->get_next_young_region()) {
 332     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 333 
 334     // The region is a non-empty survivor so let's add it to
 335     // the incremental collection set for the next evacuation
 336     // pause.
 337     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 338     young_index_in_cset += 1;
 339   }
 340   assert((size_t) young_index_in_cset == _survivor_length,
 341          "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("  [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
 373                              "age: %4d, y: %d, surv: %d",
 374                              curr->bottom(), curr->end(),
 375                              curr->top(),
 376                              curr->prev_top_at_mark_start(),
 377                              curr->next_top_at_mark_start(),
 378                              curr->top_at_conc_mark_count(),
 379                              curr->age_in_surv_rate_group_cond(),
 380                              curr->is_young(),
 381                              curr->is_survivor());
 382       curr = curr->get_next_young_region();
 383     }
 384   }
 385 
 386   gclog_or_tty->print_cr("");
 387 }
 388 
 389 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 390 {
 391   // Claim the right to put the region on the dirty cards region list
 392   // by installing a self pointer.
 393   HeapRegion* next = hr->get_next_dirty_cards_region();
 394   if (next == NULL) {
 395     HeapRegion* res = (HeapRegion*)
 396       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 397                           NULL);
 398     if (res == NULL) {
 399       HeapRegion* head;
 400       do {
 401         // Put the region to the dirty cards region list.
 402         head = _dirty_cards_region_list;
 403         next = (HeapRegion*)
 404           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 405         if (next == head) {
 406           assert(hr->get_next_dirty_cards_region() == hr,
 407                  "hr->get_next_dirty_cards_region() != hr");
 408           if (next == NULL) {
 409             // The last region in the list points to itself.
 410             hr->set_next_dirty_cards_region(hr);
 411           } else {
 412             hr->set_next_dirty_cards_region(next);
 413           }
 414         }
 415       } while (next != head);
 416     }
 417   }
 418 }
 419 
 420 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 421 {
 422   HeapRegion* head;
 423   HeapRegion* hr;
 424   do {
 425     head = _dirty_cards_region_list;
 426     if (head == NULL) {
 427       return NULL;
 428     }
 429     HeapRegion* new_head = head->get_next_dirty_cards_region();
 430     if (head == new_head) {
 431       // The last region.
 432       new_head = NULL;
 433     }
 434     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 435                                           head);
 436   } while (hr != head);
 437   assert(hr != NULL, "invariant");
 438   hr->set_next_dirty_cards_region(NULL);
 439   return hr;
 440 }
 441 
 442 void G1CollectedHeap::stop_conc_gc_threads() {
 443   _cg1r->stop();
 444   _cmThread->stop();
 445 }
 446 
 447 #ifdef ASSERT
 448 // A region is added to the collection set as it is retired
 449 // so an address p can point to a region which will be in the
 450 // collection set but has not yet been retired.  This method
 451 // therefore is only accurate during a GC pause after all
 452 // regions have been retired.  It is used for debugging
 453 // to check if an nmethod has references to objects that can
 454 // be move during a partial collection.  Though it can be
 455 // inaccurate, it is sufficient for G1 because the conservative
 456 // implementation of is_scavengable() for G1 will indicate that
 457 // all nmethods must be scanned during a partial collection.
 458 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
 459   HeapRegion* hr = heap_region_containing(p);
 460   return hr != NULL && hr->in_collection_set();
 461 }
 462 #endif
 463 
 464 // Returns true if the reference points to an object that
 465 // can move in an incremental collecction.
 466 bool G1CollectedHeap::is_scavengable(const void* p) {
 467   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 468   G1CollectorPolicy* g1p = g1h->g1_policy();
 469   HeapRegion* hr = heap_region_containing(p);
 470   if (hr == NULL) {
 471      // perm gen (or null)
 472      return false;
 473   } else {
 474     return !hr->isHumongous();
 475   }
 476 }
 477 
 478 void G1CollectedHeap::check_ct_logs_at_safepoint() {
 479   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 480   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
 481 
 482   // Count the dirty cards at the start.
 483   CountNonCleanMemRegionClosure count1(this);
 484   ct_bs->mod_card_iterate(&count1);
 485   int orig_count = count1.n();
 486 
 487   // First clear the logged cards.
 488   ClearLoggedCardTableEntryClosure clear;
 489   dcqs.set_closure(&clear);
 490   dcqs.apply_closure_to_all_completed_buffers();
 491   dcqs.iterate_closure_all_threads(false);
 492   clear.print_histo();
 493 
 494   // Now ensure that there's no dirty cards.
 495   CountNonCleanMemRegionClosure count2(this);
 496   ct_bs->mod_card_iterate(&count2);
 497   if (count2.n() != 0) {
 498     gclog_or_tty->print_cr("Card table has %d entries; %d originally",
 499                            count2.n(), orig_count);
 500   }
 501   guarantee(count2.n() == 0, "Card table should be clean.");
 502 
 503   RedirtyLoggedCardTableEntryClosure redirty;
 504   JavaThread::dirty_card_queue_set().set_closure(&redirty);
 505   dcqs.apply_closure_to_all_completed_buffers();
 506   dcqs.iterate_closure_all_threads(false);
 507   gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
 508                          clear.calls(), orig_count);
 509   guarantee(redirty.calls() == clear.calls(),
 510             "Or else mechanism is broken.");
 511 
 512   CountNonCleanMemRegionClosure count3(this);
 513   ct_bs->mod_card_iterate(&count3);
 514   if (count3.n() != orig_count) {
 515     gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
 516                            orig_count, count3.n());
 517     guarantee(count3.n() >= orig_count, "Should have restored them all.");
 518   }
 519 
 520   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
 521 }
 522 
 523 // Private class members.
 524 
 525 G1CollectedHeap* G1CollectedHeap::_g1h;
 526 
 527 // Private methods.
 528 
 529 HeapRegion*
 530 G1CollectedHeap::new_region_try_secondary_free_list() {
 531   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 532   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 533     if (!_secondary_free_list.is_empty()) {
 534       if (G1ConcRegionFreeingVerbose) {
 535         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 536                                "secondary_free_list has "SIZE_FORMAT" entries",
 537                                _secondary_free_list.length());
 538       }
 539       // It looks as if there are free regions available on the
 540       // secondary_free_list. Let's move them to the free_list and try
 541       // again to allocate from it.
 542       append_secondary_free_list();
 543 
 544       assert(!_free_list.is_empty(), "if the secondary_free_list was not "
 545              "empty we should have moved at least one entry to the free_list");
 546       HeapRegion* res = _free_list.remove_head();
 547       if (G1ConcRegionFreeingVerbose) {
 548         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 549                                "allocated "HR_FORMAT" from secondary_free_list",
 550                                HR_FORMAT_PARAMS(res));
 551       }
 552       return res;
 553     }
 554 
 555     // Wait here until we get notifed either when (a) there are no
 556     // more free regions coming or (b) some regions have been moved on
 557     // the secondary_free_list.
 558     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 559   }
 560 
 561   if (G1ConcRegionFreeingVerbose) {
 562     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 563                            "could not allocate from secondary_free_list");
 564   }
 565   return NULL;
 566 }
 567 
 568 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
 569   assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
 570          "the only time we use this to allocate a humongous region is "
 571          "when we are allocating a single humongous region");
 572 
 573   HeapRegion* res;
 574   if (G1StressConcRegionFreeing) {
 575     if (!_secondary_free_list.is_empty()) {
 576       if (G1ConcRegionFreeingVerbose) {
 577         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 578                                "forced to look at the secondary_free_list");
 579       }
 580       res = new_region_try_secondary_free_list();
 581       if (res != NULL) {
 582         return res;
 583       }
 584     }
 585   }
 586   res = _free_list.remove_head_or_null();
 587   if (res == NULL) {
 588     if (G1ConcRegionFreeingVerbose) {
 589       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 590                              "res == NULL, trying the secondary_free_list");
 591     }
 592     res = new_region_try_secondary_free_list();
 593   }
 594   if (res == NULL && do_expand) {
 595     ergo_verbose1(ErgoHeapSizing,
 596                   "attempt heap expansion",
 597                   ergo_format_reason("region allocation request failed")
 598                   ergo_format_byte("allocation request"),
 599                   word_size * HeapWordSize);
 600     if (expand(word_size * HeapWordSize)) {
 601       // Even though the heap was expanded, it might not have reached
 602       // the desired size. So, we cannot assume that the allocation
 603       // will succeed.
 604       res = _free_list.remove_head_or_null();
 605     }
 606   }
 607   return res;
 608 }
 609 
 610 size_t G1CollectedHeap::humongous_obj_allocate_find_first(size_t num_regions,
 611                                                           size_t word_size) {
 612   assert(isHumongous(word_size), "word_size should be humongous");
 613   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 614 
 615   size_t first = G1_NULL_HRS_INDEX;
 616   if (num_regions == 1) {
 617     // Only one region to allocate, no need to go through the slower
 618     // path. The caller will attempt the expasion if this fails, so
 619     // let's not try to expand here too.
 620     HeapRegion* hr = new_region(word_size, false /* do_expand */);
 621     if (hr != NULL) {
 622       first = hr->hrs_index();
 623     } else {
 624       first = G1_NULL_HRS_INDEX;
 625     }
 626   } else {
 627     // We can't allocate humongous regions while cleanupComplete() is
 628     // running, since some of the regions we find to be empty might not
 629     // yet be added to the free list and it is not straightforward to
 630     // know which list they are on so that we can remove them. Note
 631     // that we only need to do this if we need to allocate more than
 632     // one region to satisfy the current humongous allocation
 633     // request. If we are only allocating one region we use the common
 634     // region allocation code (see above).
 635     wait_while_free_regions_coming();
 636     append_secondary_free_list_if_not_empty_with_lock();
 637 
 638     if (free_regions() >= num_regions) {
 639       first = _hrs.find_contiguous(num_regions);
 640       if (first != G1_NULL_HRS_INDEX) {
 641         for (size_t i = first; i < first + num_regions; ++i) {
 642           HeapRegion* hr = region_at(i);
 643           assert(hr->is_empty(), "sanity");
 644           assert(is_on_master_free_list(hr), "sanity");
 645           hr->set_pending_removal(true);
 646         }
 647         _free_list.remove_all_pending(num_regions);
 648       }
 649     }
 650   }
 651   return first;
 652 }
 653 
 654 HeapWord*
 655 G1CollectedHeap::humongous_obj_allocate_initialize_regions(size_t first,
 656                                                            size_t num_regions,
 657                                                            size_t word_size) {
 658   assert(first != G1_NULL_HRS_INDEX, "pre-condition");
 659   assert(isHumongous(word_size), "word_size should be humongous");
 660   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 661 
 662   // Index of last region in the series + 1.
 663   size_t last = first + num_regions;
 664 
 665   // We need to initialize the region(s) we just discovered. This is
 666   // a bit tricky given that it can happen concurrently with
 667   // refinement threads refining cards on these regions and
 668   // potentially wanting to refine the BOT as they are scanning
 669   // those cards (this can happen shortly after a cleanup; see CR
 670   // 6991377). So we have to set up the region(s) carefully and in
 671   // a specific order.
 672 
 673   // The word size sum of all the regions we will allocate.
 674   size_t word_size_sum = num_regions * HeapRegion::GrainWords;
 675   assert(word_size <= word_size_sum, "sanity");
 676 
 677   // This will be the "starts humongous" region.
 678   HeapRegion* first_hr = region_at(first);
 679   // The header of the new object will be placed at the bottom of
 680   // the first region.
 681   HeapWord* new_obj = first_hr->bottom();
 682   // This will be the new end of the first region in the series that
 683   // should also match the end of the last region in the seriers.
 684   HeapWord* new_end = new_obj + word_size_sum;
 685   // This will be the new top of the first region that will reflect
 686   // this allocation.
 687   HeapWord* new_top = new_obj + word_size;
 688 
 689   // First, we need to zero the header of the space that we will be
 690   // allocating. When we update top further down, some refinement
 691   // threads might try to scan the region. By zeroing the header we
 692   // ensure that any thread that will try to scan the region will
 693   // come across the zero klass word and bail out.
 694   //
 695   // NOTE: It would not have been correct to have used
 696   // CollectedHeap::fill_with_object() and make the space look like
 697   // an int array. The thread that is doing the allocation will
 698   // later update the object header to a potentially different array
 699   // type and, for a very short period of time, the klass and length
 700   // fields will be inconsistent. This could cause a refinement
 701   // thread to calculate the object size incorrectly.
 702   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 703 
 704   // We will set up the first region as "starts humongous". This
 705   // will also update the BOT covering all the regions to reflect
 706   // that there is a single object that starts at the bottom of the
 707   // first region.
 708   first_hr->set_startsHumongous(new_top, new_end);
 709 
 710   // Then, if there are any, we will set up the "continues
 711   // humongous" regions.
 712   HeapRegion* hr = NULL;
 713   for (size_t i = first + 1; i < last; ++i) {
 714     hr = region_at(i);
 715     hr->set_continuesHumongous(first_hr);
 716   }
 717   // If we have "continues humongous" regions (hr != NULL), then the
 718   // end of the last one should match new_end.
 719   assert(hr == NULL || hr->end() == new_end, "sanity");
 720 
 721   // Up to this point no concurrent thread would have been able to
 722   // do any scanning on any region in this series. All the top
 723   // fields still point to bottom, so the intersection between
 724   // [bottom,top] and [card_start,card_end] will be empty. Before we
 725   // update the top fields, we'll do a storestore to make sure that
 726   // no thread sees the update to top before the zeroing of the
 727   // object header and the BOT initialization.
 728   OrderAccess::storestore();
 729 
 730   // Now that the BOT and the object header have been initialized,
 731   // we can update top of the "starts humongous" region.
 732   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 733          "new_top should be in this region");
 734   first_hr->set_top(new_top);
 735   if (_hr_printer.is_active()) {
 736     HeapWord* bottom = first_hr->bottom();
 737     HeapWord* end = first_hr->orig_end();
 738     if ((first + 1) == last) {
 739       // the series has a single humongous region
 740       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 741     } else {
 742       // the series has more than one humongous regions
 743       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 744     }
 745   }
 746 
 747   // Now, we will update the top fields of the "continues humongous"
 748   // regions. The reason we need to do this is that, otherwise,
 749   // these regions would look empty and this will confuse parts of
 750   // G1. For example, the code that looks for a consecutive number
 751   // of empty regions will consider them empty and try to
 752   // re-allocate them. We can extend is_empty() to also include
 753   // !continuesHumongous(), but it is easier to just update the top
 754   // fields here. The way we set top for all regions (i.e., top ==
 755   // end for all regions but the last one, top == new_top for the
 756   // last one) is actually used when we will free up the humongous
 757   // region in free_humongous_region().
 758   hr = NULL;
 759   for (size_t i = first + 1; i < last; ++i) {
 760     hr = region_at(i);
 761     if ((i + 1) == last) {
 762       // last continues humongous region
 763       assert(hr->bottom() < new_top && new_top <= hr->end(),
 764              "new_top should fall on this region");
 765       hr->set_top(new_top);
 766       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 767     } else {
 768       // not last one
 769       assert(new_top > hr->end(), "new_top should be above this region");
 770       hr->set_top(hr->end());
 771       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 772     }
 773   }
 774   // If we have continues humongous regions (hr != NULL), then the
 775   // end of the last one should match new_end and its top should
 776   // match new_top.
 777   assert(hr == NULL ||
 778          (hr->end() == new_end && hr->top() == new_top), "sanity");
 779 
 780   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 781   _summary_bytes_used += first_hr->used();
 782   _humongous_set.add(first_hr);
 783 
 784   return new_obj;
 785 }
 786 
 787 // If could fit into free regions w/o expansion, try.
 788 // Otherwise, if can expand, do so.
 789 // Otherwise, if using ex regions might help, try with ex given back.
 790 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 791   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 792 
 793   verify_region_sets_optional();
 794 
 795   size_t num_regions =
 796          round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 797   size_t x_size = expansion_regions();
 798   size_t fs = _hrs.free_suffix();
 799   size_t first = humongous_obj_allocate_find_first(num_regions, word_size);
 800   if (first == G1_NULL_HRS_INDEX) {
 801     // The only thing we can do now is attempt expansion.
 802     if (fs + x_size >= num_regions) {
 803       // If the number of regions we're trying to allocate for this
 804       // object is at most the number of regions in the free suffix,
 805       // then the call to humongous_obj_allocate_find_first() above
 806       // should have succeeded and we wouldn't be here.
 807       //
 808       // We should only be trying to expand when the free suffix is
 809       // not sufficient for the object _and_ we have some expansion
 810       // room available.
 811       assert(num_regions > fs, "earlier allocation should have succeeded");
 812 
 813       ergo_verbose1(ErgoHeapSizing,
 814                     "attempt heap expansion",
 815                     ergo_format_reason("humongous allocation request failed")
 816                     ergo_format_byte("allocation request"),
 817                     word_size * HeapWordSize);
 818       if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
 819         // Even though the heap was expanded, it might not have
 820         // reached the desired size. So, we cannot assume that the
 821         // allocation will succeed.
 822         first = humongous_obj_allocate_find_first(num_regions, word_size);
 823       }
 824     }
 825   }
 826 
 827   HeapWord* result = NULL;
 828   if (first != G1_NULL_HRS_INDEX) {
 829     result =
 830       humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
 831     assert(result != NULL, "it should always return a valid result");
 832 
 833     // A successful humongous object allocation changes the used space
 834     // information of the old generation so we need to recalculate the
 835     // sizes and update the jstat counters here.
 836     g1mm()->update_sizes();
 837   }
 838 
 839   verify_region_sets_optional();
 840 
 841   return result;
 842 }
 843 
 844 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 845   assert_heap_not_locked_and_not_at_safepoint();
 846   assert(!isHumongous(word_size), "we do not allow humongous TLABs");
 847 
 848   unsigned int dummy_gc_count_before;
 849   return attempt_allocation(word_size, &dummy_gc_count_before);
 850 }
 851 
 852 HeapWord*
 853 G1CollectedHeap::mem_allocate(size_t word_size,
 854                               bool*  gc_overhead_limit_was_exceeded) {
 855   assert_heap_not_locked_and_not_at_safepoint();
 856 
 857   // Loop until the allocation is satisified, or unsatisfied after GC.
 858   for (int try_count = 1; /* we'll return */; try_count += 1) {
 859     unsigned int gc_count_before;
 860 
 861     HeapWord* result = NULL;
 862     if (!isHumongous(word_size)) {
 863       result = attempt_allocation(word_size, &gc_count_before);
 864     } else {
 865       result = attempt_allocation_humongous(word_size, &gc_count_before);
 866     }
 867     if (result != NULL) {
 868       return result;
 869     }
 870 
 871     // Create the garbage collection operation...
 872     VM_G1CollectForAllocation op(gc_count_before, word_size);
 873     // ...and get the VM thread to execute it.
 874     VMThread::execute(&op);
 875 
 876     if (op.prologue_succeeded() && op.pause_succeeded()) {
 877       // If the operation was successful we'll return the result even
 878       // if it is NULL. If the allocation attempt failed immediately
 879       // after a Full GC, it's unlikely we'll be able to allocate now.
 880       HeapWord* result = op.result();
 881       if (result != NULL && !isHumongous(word_size)) {
 882         // Allocations that take place on VM operations do not do any
 883         // card dirtying and we have to do it here. We only have to do
 884         // this for non-humongous allocations, though.
 885         dirty_young_block(result, word_size);
 886       }
 887       return result;
 888     } else {
 889       assert(op.result() == NULL,
 890              "the result should be NULL if the VM op did not succeed");
 891     }
 892 
 893     // Give a warning if we seem to be looping forever.
 894     if ((QueuedAllocationWarningCount > 0) &&
 895         (try_count % QueuedAllocationWarningCount == 0)) {
 896       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 897     }
 898   }
 899 
 900   ShouldNotReachHere();
 901   return NULL;
 902 }
 903 
 904 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 905                                            unsigned int *gc_count_before_ret) {
 906   // Make sure you read the note in attempt_allocation_humongous().
 907 
 908   assert_heap_not_locked_and_not_at_safepoint();
 909   assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
 910          "be called for humongous allocation requests");
 911 
 912   // We should only get here after the first-level allocation attempt
 913   // (attempt_allocation()) failed to allocate.
 914 
 915   // We will loop until a) we manage to successfully perform the
 916   // allocation or b) we successfully schedule a collection which
 917   // fails to perform the allocation. b) is the only case when we'll
 918   // return NULL.
 919   HeapWord* result = NULL;
 920   for (int try_count = 1; /* we'll return */; try_count += 1) {
 921     bool should_try_gc;
 922     unsigned int gc_count_before;
 923 
 924     {
 925       MutexLockerEx x(Heap_lock);
 926 
 927       result = _mutator_alloc_region.attempt_allocation_locked(word_size,
 928                                                       false /* bot_updates */);
 929       if (result != NULL) {
 930         return result;
 931       }
 932 
 933       // If we reach here, attempt_allocation_locked() above failed to
 934       // allocate a new region. So the mutator alloc region should be NULL.
 935       assert(_mutator_alloc_region.get() == NULL, "only way to get here");
 936 
 937       if (GC_locker::is_active_and_needs_gc()) {
 938         if (g1_policy()->can_expand_young_list()) {
 939           // No need for an ergo verbose message here,
 940           // can_expand_young_list() does this when it returns true.
 941           result = _mutator_alloc_region.attempt_allocation_force(word_size,
 942                                                       false /* bot_updates */);
 943           if (result != NULL) {
 944             return result;
 945           }
 946         }
 947         should_try_gc = false;
 948       } else {
 949         // Read the GC count while still holding the Heap_lock.
 950         gc_count_before = SharedHeap::heap()->total_collections();
 951         should_try_gc = true;
 952       }
 953     }
 954 
 955     if (should_try_gc) {
 956       bool succeeded;
 957       result = do_collection_pause(word_size, gc_count_before, &succeeded);
 958       if (result != NULL) {
 959         assert(succeeded, "only way to get back a non-NULL result");
 960         return result;
 961       }
 962 
 963       if (succeeded) {
 964         // If we get here we successfully scheduled a collection which
 965         // failed to allocate. No point in trying to allocate
 966         // further. We'll just return NULL.
 967         MutexLockerEx x(Heap_lock);
 968         *gc_count_before_ret = SharedHeap::heap()->total_collections();
 969         return NULL;
 970       }
 971     } else {
 972       GC_locker::stall_until_clear();
 973     }
 974 
 975     // We can reach here if we were unsuccessul in scheduling a
 976     // collection (because another thread beat us to it) or if we were
 977     // stalled due to the GC locker. In either can we should retry the
 978     // allocation attempt in case another thread successfully
 979     // performed a collection and reclaimed enough space. We do the
 980     // first attempt (without holding the Heap_lock) here and the
 981     // follow-on attempt will be at the start of the next loop
 982     // iteration (after taking the Heap_lock).
 983     result = _mutator_alloc_region.attempt_allocation(word_size,
 984                                                       false /* bot_updates */);
 985     if (result != NULL ){
 986       return result;
 987     }
 988 
 989     // Give a warning if we seem to be looping forever.
 990     if ((QueuedAllocationWarningCount > 0) &&
 991         (try_count % QueuedAllocationWarningCount == 0)) {
 992       warning("G1CollectedHeap::attempt_allocation_slow() "
 993               "retries %d times", try_count);
 994     }
 995   }
 996 
 997   ShouldNotReachHere();
 998   return NULL;
 999 }
1000 
1001 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1002                                           unsigned int * gc_count_before_ret) {
1003   // The structure of this method has a lot of similarities to
1004   // attempt_allocation_slow(). The reason these two were not merged
1005   // into a single one is that such a method would require several "if
1006   // allocation is not humongous do this, otherwise do that"
1007   // conditional paths which would obscure its flow. In fact, an early
1008   // version of this code did use a unified method which was harder to
1009   // follow and, as a result, it had subtle bugs that were hard to
1010   // track down. So keeping these two methods separate allows each to
1011   // be more readable. It will be good to keep these two in sync as
1012   // much as possible.
1013 
1014   assert_heap_not_locked_and_not_at_safepoint();
1015   assert(isHumongous(word_size), "attempt_allocation_humongous() "
1016          "should only be called for humongous allocations");
1017 
1018   // We will loop until a) we manage to successfully perform the
1019   // allocation or b) we successfully schedule a collection which
1020   // fails to perform the allocation. b) is the only case when we'll
1021   // return NULL.
1022   HeapWord* result = NULL;
1023   for (int try_count = 1; /* we'll return */; try_count += 1) {
1024     bool should_try_gc;
1025     unsigned int gc_count_before;
1026 
1027     {
1028       MutexLockerEx x(Heap_lock);
1029 
1030       // Given that humongous objects are not allocated in young
1031       // regions, we'll first try to do the allocation without doing a
1032       // collection hoping that there's enough space in the heap.
1033       result = humongous_obj_allocate(word_size);
1034       if (result != NULL) {
1035         return result;
1036       }
1037 
1038       if (GC_locker::is_active_and_needs_gc()) {
1039         should_try_gc = false;
1040       } else {
1041         // Read the GC count while still holding the Heap_lock.
1042         gc_count_before = SharedHeap::heap()->total_collections();
1043         should_try_gc = true;
1044       }
1045     }
1046 
1047     if (should_try_gc) {
1048       // If we failed to allocate the humongous object, we should try to
1049       // do a collection pause (if we're allowed) in case it reclaims
1050       // enough space for the allocation to succeed after the pause.
1051 
1052       bool succeeded;
1053       result = do_collection_pause(word_size, gc_count_before, &succeeded);
1054       if (result != NULL) {
1055         assert(succeeded, "only way to get back a non-NULL result");
1056         return result;
1057       }
1058 
1059       if (succeeded) {
1060         // If we get here we successfully scheduled a collection which
1061         // failed to allocate. No point in trying to allocate
1062         // further. We'll just return NULL.
1063         MutexLockerEx x(Heap_lock);
1064         *gc_count_before_ret = SharedHeap::heap()->total_collections();
1065         return NULL;
1066       }
1067     } else {
1068       GC_locker::stall_until_clear();
1069     }
1070 
1071     // We can reach here if we were unsuccessul in scheduling a
1072     // collection (because another thread beat us to it) or if we were
1073     // stalled due to the GC locker. In either can we should retry the
1074     // allocation attempt in case another thread successfully
1075     // performed a collection and reclaimed enough space.  Give a
1076     // warning if we seem to be looping forever.
1077 
1078     if ((QueuedAllocationWarningCount > 0) &&
1079         (try_count % QueuedAllocationWarningCount == 0)) {
1080       warning("G1CollectedHeap::attempt_allocation_humongous() "
1081               "retries %d times", try_count);
1082     }
1083   }
1084 
1085   ShouldNotReachHere();
1086   return NULL;
1087 }
1088 
1089 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1090                                        bool expect_null_mutator_alloc_region) {
1091   assert_at_safepoint(true /* should_be_vm_thread */);
1092   assert(_mutator_alloc_region.get() == NULL ||
1093                                              !expect_null_mutator_alloc_region,
1094          "the current alloc region was unexpectedly found to be non-NULL");
1095 
1096   if (!isHumongous(word_size)) {
1097     return _mutator_alloc_region.attempt_allocation_locked(word_size,
1098                                                       false /* bot_updates */);
1099   } else {
1100     return humongous_obj_allocate(word_size);
1101   }
1102 
1103   ShouldNotReachHere();
1104 }
1105 
1106 class PostMCRemSetClearClosure: public HeapRegionClosure {
1107   ModRefBarrierSet* _mr_bs;
1108 public:
1109   PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1110   bool doHeapRegion(HeapRegion* r) {
1111     r->reset_gc_time_stamp();
1112     if (r->continuesHumongous())
1113       return false;
1114     HeapRegionRemSet* hrrs = r->rem_set();
1115     if (hrrs != NULL) hrrs->clear();
1116     // You might think here that we could clear just the cards
1117     // corresponding to the used region.  But no: if we leave a dirty card
1118     // in a region we might allocate into, then it would prevent that card
1119     // from being enqueued, and cause it to be missed.
1120     // Re: the performance cost: we shouldn't be doing full GC anyway!
1121     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1122     return false;
1123   }
1124 };
1125 
1126 
1127 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
1128   ModRefBarrierSet* _mr_bs;
1129 public:
1130   PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1131   bool doHeapRegion(HeapRegion* r) {
1132     if (r->continuesHumongous()) return false;
1133     if (r->used_region().word_size() != 0) {
1134       _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
1135     }
1136     return false;
1137   }
1138 };
1139 
1140 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1141   G1CollectedHeap*   _g1h;
1142   UpdateRSOopClosure _cl;
1143   int                _worker_i;
1144 public:
1145   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1146     _cl(g1->g1_rem_set(), worker_i),
1147     _worker_i(worker_i),
1148     _g1h(g1)
1149   { }
1150 
1151   bool doHeapRegion(HeapRegion* r) {
1152     if (!r->continuesHumongous()) {
1153       _cl.set_from(r);
1154       r->oop_iterate(&_cl);
1155     }
1156     return false;
1157   }
1158 };
1159 
1160 class ParRebuildRSTask: public AbstractGangTask {
1161   G1CollectedHeap* _g1;
1162 public:
1163   ParRebuildRSTask(G1CollectedHeap* g1)
1164     : AbstractGangTask("ParRebuildRSTask"),
1165       _g1(g1)
1166   { }
1167 
1168   void work(int i) {
1169     RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
1170     _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
1171                                           _g1->workers()->active_workers(),
1172                                          HeapRegion::RebuildRSClaimValue);
1173   }
1174 };
1175 
1176 class PostCompactionPrinterClosure: public HeapRegionClosure {
1177 private:
1178   G1HRPrinter* _hr_printer;
1179 public:
1180   bool doHeapRegion(HeapRegion* hr) {
1181     assert(!hr->is_young(), "not expecting to find young regions");
1182     // We only generate output for non-empty regions.
1183     if (!hr->is_empty()) {
1184       if (!hr->isHumongous()) {
1185         _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1186       } else if (hr->startsHumongous()) {
1187         if (hr->capacity() == HeapRegion::GrainBytes) {
1188           // single humongous region
1189           _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1190         } else {
1191           _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1192         }
1193       } else {
1194         assert(hr->continuesHumongous(), "only way to get here");
1195         _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1196       }
1197     }
1198     return false;
1199   }
1200 
1201   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1202     : _hr_printer(hr_printer) { }
1203 };
1204 
1205 bool G1CollectedHeap::do_collection(bool explicit_gc,
1206                                     bool clear_all_soft_refs,
1207                                     size_t word_size) {
1208   assert_at_safepoint(true /* should_be_vm_thread */);
1209 
1210   if (GC_locker::check_active_before_gc()) {
1211     return false;
1212   }
1213 
1214   SvcGCMarker sgcm(SvcGCMarker::FULL);
1215   ResourceMark rm;
1216 
1217   if (PrintHeapAtGC) {
1218     Universe::print_heap_before_gc();
1219   }
1220 
1221   HRSPhaseSetter x(HRSPhaseFullGC);
1222   verify_region_sets_optional();
1223 
1224   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1225                            collector_policy()->should_clear_all_soft_refs();
1226 
1227   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1228 
1229   {
1230     IsGCActiveMark x;
1231 
1232     // Timing
1233     bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc);
1234     assert(!system_gc || explicit_gc, "invariant");
1235     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
1236     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
1237     TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC",
1238                 PrintGC, true, gclog_or_tty);
1239 
1240     TraceCollectorStats tcs(g1mm()->full_collection_counters());
1241     TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1242 
1243     double start = os::elapsedTime();
1244     g1_policy()->record_full_collection_start();
1245 
1246     wait_while_free_regions_coming();
1247     append_secondary_free_list_if_not_empty_with_lock();
1248 
1249     gc_prologue(true);
1250     increment_total_collections(true /* full gc */);
1251 
1252     size_t g1h_prev_used = used();
1253     assert(used() == recalculate_used(), "Should be equal");
1254 
1255     if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
1256       HandleMark hm;  // Discard invalid handles created during verification
1257       gclog_or_tty->print(" VerifyBeforeGC:");
1258       prepare_for_verify();
1259       Universe::verify(/* allow dirty */ true,
1260                        /* silent      */ false,
1261                        /* option      */ VerifyOption_G1UsePrevMarking);
1262 
1263     }
1264     pre_full_gc_dump();
1265 
1266     COMPILER2_PRESENT(DerivedPointerTable::clear());
1267 
1268     // Disable discovery and empty the discovered lists
1269     // for the CM ref processor.
1270     ref_processor_cm()->disable_discovery();
1271     ref_processor_cm()->abandon_partial_discovery();
1272     ref_processor_cm()->verify_no_references_recorded();
1273 
1274     // Abandon current iterations of concurrent marking and concurrent
1275     // refinement, if any are in progress.
1276     concurrent_mark()->abort();
1277 
1278     // Make sure we'll choose a new allocation region afterwards.
1279     release_mutator_alloc_region();
1280     abandon_gc_alloc_regions();
1281     g1_rem_set()->cleanupHRRS();
1282 
1283     // We should call this after we retire any currently active alloc
1284     // regions so that all the ALLOC / RETIRE events are generated
1285     // before the start GC event.
1286     _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1287 
1288     // We may have added regions to the current incremental collection
1289     // set between the last GC or pause and now. We need to clear the
1290     // incremental collection set and then start rebuilding it afresh
1291     // after this full GC.
1292     abandon_collection_set(g1_policy()->inc_cset_head());
1293     g1_policy()->clear_incremental_cset();
1294     g1_policy()->stop_incremental_cset_building();
1295 
1296     tear_down_region_sets(false /* free_list_only */);
1297     g1_policy()->set_gcs_are_young(true);
1298 
1299     // See the comments in g1CollectedHeap.hpp and
1300     // G1CollectedHeap::ref_processing_init() about
1301     // how reference processing currently works in G1.
1302 
1303     // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1304     ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1305 
1306     // Temporarily clear the STW ref processor's _is_alive_non_header field.
1307     ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1308 
1309     ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1310     ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1311 
1312     // Do collection work
1313     {
1314       HandleMark hm;  // Discard invalid handles created during gc
1315       G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1316     }
1317 
1318     assert(free_regions() == 0, "we should not have added any free regions");
1319     rebuild_region_sets(false /* free_list_only */);
1320 
1321     // Enqueue any discovered reference objects that have
1322     // not been removed from the discovered lists.
1323     ref_processor_stw()->enqueue_discovered_references();
1324 
1325     COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1326 
1327     MemoryService::track_memory_usage();
1328 
1329     if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1330       HandleMark hm;  // Discard invalid handles created during verification
1331       gclog_or_tty->print(" VerifyAfterGC:");
1332       prepare_for_verify();
1333       Universe::verify(/* allow dirty */ false,
1334                        /* silent      */ false,
1335                        /* option      */ VerifyOption_G1UsePrevMarking);
1336 
1337     }
1338 
1339     assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1340     ref_processor_stw()->verify_no_references_recorded();
1341 
1342     // Note: since we've just done a full GC, concurrent
1343     // marking is no longer active. Therefore we need not
1344     // re-enable reference discovery for the CM ref processor.
1345     // That will be done at the start of the next marking cycle.
1346     assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1347     ref_processor_cm()->verify_no_references_recorded();
1348 
1349     reset_gc_time_stamp();
1350     // Since everything potentially moved, we will clear all remembered
1351     // sets, and clear all cards.  Later we will rebuild remebered
1352     // sets. We will also reset the GC time stamps of the regions.
1353     PostMCRemSetClearClosure rs_clear(mr_bs());
1354     heap_region_iterate(&rs_clear);
1355 
1356     // Resize the heap if necessary.
1357     resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1358 
1359     if (_hr_printer.is_active()) {
1360       // We should do this after we potentially resize the heap so
1361       // that all the COMMIT / UNCOMMIT events are generated before
1362       // the end GC event.
1363 
1364       PostCompactionPrinterClosure cl(hr_printer());
1365       heap_region_iterate(&cl);
1366 
1367       _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1368     }
1369 
1370     if (_cg1r->use_cache()) {
1371       _cg1r->clear_and_record_card_counts();
1372       _cg1r->clear_hot_cache();
1373     }
1374 
1375     // Rebuild remembered sets of all regions.
1376     if (G1CollectedHeap::use_parallel_gc_threads()) {
1377       int n_workers =
1378         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1379                                        workers()->active_workers(),
1380                                        Threads::number_of_non_daemon_threads());
1381       assert(UseDynamicNumberOfGCThreads ||
1382              n_workers == workers()->total_workers(),
1383              "If not dynamic should be using all the  workers");
1384       workers()->set_active_workers(n_workers);
1385       // Set parallel threads in the heap (_n_par_threads) only
1386       // before a parallel phase and always reset it to 0 after
1387       // the phase so that the number of parallel threads does
1388       // no get carried forward to a serial phase where there
1389       // may be code that is "possibly_parallel".
1390       set_par_threads(n_workers);
1391 
1392       ParRebuildRSTask rebuild_rs_task(this);
1393       assert(check_heap_region_claim_values(
1394              HeapRegion::InitialClaimValue), "sanity check");
1395       assert(UseDynamicNumberOfGCThreads ||
1396              workers()->active_workers() == workers()->total_workers(),
1397         "Unless dynamic should use total workers");
1398       // Use the most recent number of  active workers
1399       assert(workers()->active_workers() > 0,
1400         "Active workers not properly set");
1401       set_par_threads(workers()->active_workers());
1402       workers()->run_task(&rebuild_rs_task);
1403       set_par_threads(0);
1404       assert(check_heap_region_claim_values(
1405              HeapRegion::RebuildRSClaimValue), "sanity check");
1406       reset_heap_region_claim_values();
1407     } else {
1408       RebuildRSOutOfRegionClosure rebuild_rs(this);
1409       heap_region_iterate(&rebuild_rs);
1410     }
1411 
1412     if (PrintGC) {
1413       print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1414     }
1415 
1416     if (true) { // FIXME
1417       // Ask the permanent generation to adjust size for full collections
1418       perm()->compute_new_size();
1419     }
1420 
1421     // Start a new incremental collection set for the next pause
1422     assert(g1_policy()->collection_set() == NULL, "must be");
1423     g1_policy()->start_incremental_cset_building();
1424 
1425     // Clear the _cset_fast_test bitmap in anticipation of adding
1426     // regions to the incremental collection set for the next
1427     // evacuation pause.
1428     clear_cset_fast_test();
1429 
1430     init_mutator_alloc_region();
1431 
1432     double end = os::elapsedTime();
1433     g1_policy()->record_full_collection_end();
1434 
1435 #ifdef TRACESPINNING
1436     ParallelTaskTerminator::print_termination_counts();
1437 #endif
1438 
1439     gc_epilogue(true);
1440 
1441     // Discard all rset updates
1442     JavaThread::dirty_card_queue_set().abandon_logs();
1443     assert(!G1DeferredRSUpdate
1444            || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1445   }
1446 
1447   _young_list->reset_sampled_info();
1448   // At this point there should be no regions in the
1449   // entire heap tagged as young.
1450   assert( check_young_list_empty(true /* check_heap */),
1451     "young list should be empty at this point");
1452 
1453   // Update the number of full collections that have been completed.
1454   increment_full_collections_completed(false /* concurrent */);
1455 
1456   _hrs.verify_optional();
1457   verify_region_sets_optional();
1458 
1459   if (PrintHeapAtGC) {
1460     Universe::print_heap_after_gc();
1461   }
1462   g1mm()->update_sizes();
1463   post_full_gc_dump();
1464 
1465   return true;
1466 }
1467 
1468 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1469   // do_collection() will return whether it succeeded in performing
1470   // the GC. Currently, there is no facility on the
1471   // do_full_collection() API to notify the caller than the collection
1472   // did not succeed (e.g., because it was locked out by the GC
1473   // locker). So, right now, we'll ignore the return value.
1474   bool dummy = do_collection(true,                /* explicit_gc */
1475                              clear_all_soft_refs,
1476                              0                    /* word_size */);
1477 }
1478 
1479 // This code is mostly copied from TenuredGeneration.
1480 void
1481 G1CollectedHeap::
1482 resize_if_necessary_after_full_collection(size_t word_size) {
1483   assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1484 
1485   // Include the current allocation, if any, and bytes that will be
1486   // pre-allocated to support collections, as "used".
1487   const size_t used_after_gc = used();
1488   const size_t capacity_after_gc = capacity();
1489   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1490 
1491   // This is enforced in arguments.cpp.
1492   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1493          "otherwise the code below doesn't make sense");
1494 
1495   // We don't have floating point command-line arguments
1496   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1497   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1498   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1499   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1500 
1501   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1502   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1503 
1504   // We have to be careful here as these two calculations can overflow
1505   // 32-bit size_t's.
1506   double used_after_gc_d = (double) used_after_gc;
1507   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1508   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1509 
1510   // Let's make sure that they are both under the max heap size, which
1511   // by default will make them fit into a size_t.
1512   double desired_capacity_upper_bound = (double) max_heap_size;
1513   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1514                                     desired_capacity_upper_bound);
1515   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1516                                     desired_capacity_upper_bound);
1517 
1518   // We can now safely turn them into size_t's.
1519   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1520   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1521 
1522   // This assert only makes sense here, before we adjust them
1523   // with respect to the min and max heap size.
1524   assert(minimum_desired_capacity <= maximum_desired_capacity,
1525          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1526                  "maximum_desired_capacity = "SIZE_FORMAT,
1527                  minimum_desired_capacity, maximum_desired_capacity));
1528 
1529   // Should not be greater than the heap max size. No need to adjust
1530   // it with respect to the heap min size as it's a lower bound (i.e.,
1531   // we'll try to make the capacity larger than it, not smaller).
1532   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1533   // Should not be less than the heap min size. No need to adjust it
1534   // with respect to the heap max size as it's an upper bound (i.e.,
1535   // we'll try to make the capacity smaller than it, not greater).
1536   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1537 
1538   if (capacity_after_gc < minimum_desired_capacity) {
1539     // Don't expand unless it's significant
1540     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1541     ergo_verbose4(ErgoHeapSizing,
1542                   "attempt heap expansion",
1543                   ergo_format_reason("capacity lower than "
1544                                      "min desired capacity after Full GC")
1545                   ergo_format_byte("capacity")
1546                   ergo_format_byte("occupancy")
1547                   ergo_format_byte_perc("min desired capacity"),
1548                   capacity_after_gc, used_after_gc,
1549                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1550     expand(expand_bytes);
1551 
1552     // No expansion, now see if we want to shrink
1553   } else if (capacity_after_gc > maximum_desired_capacity) {
1554     // Capacity too large, compute shrinking size
1555     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1556     ergo_verbose4(ErgoHeapSizing,
1557                   "attempt heap shrinking",
1558                   ergo_format_reason("capacity higher than "
1559                                      "max desired capacity after Full GC")
1560                   ergo_format_byte("capacity")
1561                   ergo_format_byte("occupancy")
1562                   ergo_format_byte_perc("max desired capacity"),
1563                   capacity_after_gc, used_after_gc,
1564                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1565     shrink(shrink_bytes);
1566   }
1567 }
1568 
1569 
1570 HeapWord*
1571 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1572                                            bool* succeeded) {
1573   assert_at_safepoint(true /* should_be_vm_thread */);
1574 
1575   *succeeded = true;
1576   // Let's attempt the allocation first.
1577   HeapWord* result =
1578     attempt_allocation_at_safepoint(word_size,
1579                                  false /* expect_null_mutator_alloc_region */);
1580   if (result != NULL) {
1581     assert(*succeeded, "sanity");
1582     return result;
1583   }
1584 
1585   // In a G1 heap, we're supposed to keep allocation from failing by
1586   // incremental pauses.  Therefore, at least for now, we'll favor
1587   // expansion over collection.  (This might change in the future if we can
1588   // do something smarter than full collection to satisfy a failed alloc.)
1589   result = expand_and_allocate(word_size);
1590   if (result != NULL) {
1591     assert(*succeeded, "sanity");
1592     return result;
1593   }
1594 
1595   // Expansion didn't work, we'll try to do a Full GC.
1596   bool gc_succeeded = do_collection(false, /* explicit_gc */
1597                                     false, /* clear_all_soft_refs */
1598                                     word_size);
1599   if (!gc_succeeded) {
1600     *succeeded = false;
1601     return NULL;
1602   }
1603 
1604   // Retry the allocation
1605   result = attempt_allocation_at_safepoint(word_size,
1606                                   true /* expect_null_mutator_alloc_region */);
1607   if (result != NULL) {
1608     assert(*succeeded, "sanity");
1609     return result;
1610   }
1611 
1612   // Then, try a Full GC that will collect all soft references.
1613   gc_succeeded = do_collection(false, /* explicit_gc */
1614                                true,  /* clear_all_soft_refs */
1615                                word_size);
1616   if (!gc_succeeded) {
1617     *succeeded = false;
1618     return NULL;
1619   }
1620 
1621   // Retry the allocation once more
1622   result = attempt_allocation_at_safepoint(word_size,
1623                                   true /* expect_null_mutator_alloc_region */);
1624   if (result != NULL) {
1625     assert(*succeeded, "sanity");
1626     return result;
1627   }
1628 
1629   assert(!collector_policy()->should_clear_all_soft_refs(),
1630          "Flag should have been handled and cleared prior to this point");
1631 
1632   // What else?  We might try synchronous finalization later.  If the total
1633   // space available is large enough for the allocation, then a more
1634   // complete compaction phase than we've tried so far might be
1635   // appropriate.
1636   assert(*succeeded, "sanity");
1637   return NULL;
1638 }
1639 
1640 // Attempting to expand the heap sufficiently
1641 // to support an allocation of the given "word_size".  If
1642 // successful, perform the allocation and return the address of the
1643 // allocated block, or else "NULL".
1644 
1645 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1646   assert_at_safepoint(true /* should_be_vm_thread */);
1647 
1648   verify_region_sets_optional();
1649 
1650   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1651   ergo_verbose1(ErgoHeapSizing,
1652                 "attempt heap expansion",
1653                 ergo_format_reason("allocation request failed")
1654                 ergo_format_byte("allocation request"),
1655                 word_size * HeapWordSize);
1656   if (expand(expand_bytes)) {
1657     _hrs.verify_optional();
1658     verify_region_sets_optional();
1659     return attempt_allocation_at_safepoint(word_size,
1660                                  false /* expect_null_mutator_alloc_region */);
1661   }
1662   return NULL;
1663 }
1664 
1665 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1666                                              HeapWord* new_end) {
1667   assert(old_end != new_end, "don't call this otherwise");
1668   assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1669 
1670   // Update the committed mem region.
1671   _g1_committed.set_end(new_end);
1672   // Tell the card table about the update.
1673   Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1674   // Tell the BOT about the update.
1675   _bot_shared->resize(_g1_committed.word_size());
1676 }
1677 
1678 bool G1CollectedHeap::expand(size_t expand_bytes) {
1679   size_t old_mem_size = _g1_storage.committed_size();
1680   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1681   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1682                                        HeapRegion::GrainBytes);
1683   ergo_verbose2(ErgoHeapSizing,
1684                 "expand the heap",
1685                 ergo_format_byte("requested expansion amount")
1686                 ergo_format_byte("attempted expansion amount"),
1687                 expand_bytes, aligned_expand_bytes);
1688 
1689   // First commit the memory.
1690   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1691   bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1692   if (successful) {
1693     // Then propagate this update to the necessary data structures.
1694     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1695     update_committed_space(old_end, new_end);
1696 
1697     FreeRegionList expansion_list("Local Expansion List");
1698     MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1699     assert(mr.start() == old_end, "post-condition");
1700     // mr might be a smaller region than what was requested if
1701     // expand_by() was unable to allocate the HeapRegion instances
1702     assert(mr.end() <= new_end, "post-condition");
1703 
1704     size_t actual_expand_bytes = mr.byte_size();
1705     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1706     assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1707            "post-condition");
1708     if (actual_expand_bytes < aligned_expand_bytes) {
1709       // We could not expand _hrs to the desired size. In this case we
1710       // need to shrink the committed space accordingly.
1711       assert(mr.end() < new_end, "invariant");
1712 
1713       size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1714       // First uncommit the memory.
1715       _g1_storage.shrink_by(diff_bytes);
1716       // Then propagate this update to the necessary data structures.
1717       update_committed_space(new_end, mr.end());
1718     }
1719     _free_list.add_as_tail(&expansion_list);
1720 
1721     if (_hr_printer.is_active()) {
1722       HeapWord* curr = mr.start();
1723       while (curr < mr.end()) {
1724         HeapWord* curr_end = curr + HeapRegion::GrainWords;
1725         _hr_printer.commit(curr, curr_end);
1726         curr = curr_end;
1727       }
1728       assert(curr == mr.end(), "post-condition");
1729     }
1730     g1_policy()->record_new_heap_size(n_regions());
1731   } else {
1732     ergo_verbose0(ErgoHeapSizing,
1733                   "did not expand the heap",
1734                   ergo_format_reason("heap expansion operation failed"));
1735     // The expansion of the virtual storage space was unsuccessful.
1736     // Let's see if it was because we ran out of swap.
1737     if (G1ExitOnExpansionFailure &&
1738         _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1739       // We had head room...
1740       vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion");
1741     }
1742   }
1743   return successful;
1744 }
1745 
1746 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1747   size_t old_mem_size = _g1_storage.committed_size();
1748   size_t aligned_shrink_bytes =
1749     ReservedSpace::page_align_size_down(shrink_bytes);
1750   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1751                                          HeapRegion::GrainBytes);
1752   size_t num_regions_deleted = 0;
1753   MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted);
1754   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1755   assert(mr.end() == old_end, "post-condition");
1756 
1757   ergo_verbose3(ErgoHeapSizing,
1758                 "shrink the heap",
1759                 ergo_format_byte("requested shrinking amount")
1760                 ergo_format_byte("aligned shrinking amount")
1761                 ergo_format_byte("attempted shrinking amount"),
1762                 shrink_bytes, aligned_shrink_bytes, mr.byte_size());
1763   if (mr.byte_size() > 0) {
1764     if (_hr_printer.is_active()) {
1765       HeapWord* curr = mr.end();
1766       while (curr > mr.start()) {
1767         HeapWord* curr_end = curr;
1768         curr -= HeapRegion::GrainWords;
1769         _hr_printer.uncommit(curr, curr_end);
1770       }
1771       assert(curr == mr.start(), "post-condition");
1772     }
1773 
1774     _g1_storage.shrink_by(mr.byte_size());
1775     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1776     assert(mr.start() == new_end, "post-condition");
1777 
1778     _expansion_regions += num_regions_deleted;
1779     update_committed_space(old_end, new_end);
1780     HeapRegionRemSet::shrink_heap(n_regions());
1781     g1_policy()->record_new_heap_size(n_regions());
1782   } else {
1783     ergo_verbose0(ErgoHeapSizing,
1784                   "did not shrink the heap",
1785                   ergo_format_reason("heap shrinking operation failed"));
1786   }
1787 }
1788 
1789 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1790   verify_region_sets_optional();
1791 
1792   // We should only reach here at the end of a Full GC which means we
1793   // should not not be holding to any GC alloc regions. The method
1794   // below will make sure of that and do any remaining clean up.
1795   abandon_gc_alloc_regions();
1796 
1797   // Instead of tearing down / rebuilding the free lists here, we
1798   // could instead use the remove_all_pending() method on free_list to
1799   // remove only the ones that we need to remove.
1800   tear_down_region_sets(true /* free_list_only */);
1801   shrink_helper(shrink_bytes);
1802   rebuild_region_sets(true /* free_list_only */);
1803 
1804   _hrs.verify_optional();
1805   verify_region_sets_optional();
1806 }
1807 
1808 // Public methods.
1809 
1810 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1811 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1812 #endif // _MSC_VER
1813 
1814 
1815 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1816   SharedHeap(policy_),
1817   _g1_policy(policy_),
1818   _dirty_card_queue_set(false),
1819   _into_cset_dirty_card_queue_set(false),
1820   _is_alive_closure_cm(this),
1821   _is_alive_closure_stw(this),
1822   _ref_processor_cm(NULL),
1823   _ref_processor_stw(NULL),
1824   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1825   _bot_shared(NULL),
1826   _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1827   _evac_failure_scan_stack(NULL) ,
1828   _mark_in_progress(false),
1829   _cg1r(NULL), _summary_bytes_used(0),
1830   _g1mm(NULL),
1831   _refine_cte_cl(NULL),
1832   _full_collection(false),
1833   _free_list("Master Free List"),
1834   _secondary_free_list("Secondary Free List"),
1835   _old_set("Old Set"),
1836   _humongous_set("Master Humongous Set"),
1837   _free_regions_coming(false),
1838   _young_list(new YoungList(this)),
1839   _gc_time_stamp(0),
1840   _retained_old_gc_alloc_region(NULL),
1841   _surviving_young_words(NULL),
1842   _full_collections_completed(0),
1843   _in_cset_fast_test(NULL),
1844   _in_cset_fast_test_base(NULL),
1845   _dirty_cards_region_list(NULL),
1846   _worker_cset_start_region(NULL),
1847   _worker_cset_start_region_time_stamp(NULL) {
1848   _g1h = this; // To catch bugs.
1849   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1850     vm_exit_during_initialization("Failed necessary allocation.");
1851   }
1852 
1853   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1854 
1855   int n_queues = MAX2((int)ParallelGCThreads, 1);
1856   _task_queues = new RefToScanQueueSet(n_queues);
1857 
1858   int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1859   assert(n_rem_sets > 0, "Invariant.");
1860 
1861   HeapRegionRemSetIterator** iter_arr =
1862     NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1863   for (int i = 0; i < n_queues; i++) {
1864     iter_arr[i] = new HeapRegionRemSetIterator();
1865   }
1866   _rem_set_iterator = iter_arr;
1867 
1868   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues);
1869   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues);
1870 
1871   for (int i = 0; i < n_queues; i++) {
1872     RefToScanQueue* q = new RefToScanQueue();
1873     q->initialize();
1874     _task_queues->register_queue(i, q);
1875   }
1876 
1877   clear_cset_start_regions();
1878 
1879   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1880 }
1881 
1882 jint G1CollectedHeap::initialize() {
1883   CollectedHeap::pre_initialize();
1884   os::enable_vtime();
1885 
1886   // Necessary to satisfy locking discipline assertions.
1887 
1888   MutexLocker x(Heap_lock);
1889 
1890   // We have to initialize the printer before committing the heap, as
1891   // it will be used then.
1892   _hr_printer.set_active(G1PrintHeapRegions);
1893 
1894   // While there are no constraints in the GC code that HeapWordSize
1895   // be any particular value, there are multiple other areas in the
1896   // system which believe this to be true (e.g. oop->object_size in some
1897   // cases incorrectly returns the size in wordSize units rather than
1898   // HeapWordSize).
1899   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1900 
1901   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1902   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1903 
1904   // Ensure that the sizes are properly aligned.
1905   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1906   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1907 
1908   _cg1r = new ConcurrentG1Refine();
1909 
1910   // Reserve the maximum.
1911   PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1912   // Includes the perm-gen.
1913 
1914   // When compressed oops are enabled, the preferred heap base
1915   // is calculated by subtracting the requested size from the
1916   // 32Gb boundary and using the result as the base address for
1917   // heap reservation. If the requested size is not aligned to
1918   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1919   // into the ReservedHeapSpace constructor) then the actual
1920   // base of the reserved heap may end up differing from the
1921   // address that was requested (i.e. the preferred heap base).
1922   // If this happens then we could end up using a non-optimal
1923   // compressed oops mode.
1924 
1925   // Since max_byte_size is aligned to the size of a heap region (checked
1926   // above), we also need to align the perm gen size as it might not be.
1927   const size_t total_reserved = max_byte_size +
1928                                 align_size_up(pgs->max_size(), HeapRegion::GrainBytes);
1929   Universe::check_alignment(total_reserved, HeapRegion::GrainBytes, "g1 heap and perm");
1930 
1931   char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1932 
1933   ReservedHeapSpace heap_rs(total_reserved, HeapRegion::GrainBytes,
1934                             UseLargePages, addr);
1935 
1936   if (UseCompressedOops) {
1937     if (addr != NULL && !heap_rs.is_reserved()) {
1938       // Failed to reserve at specified address - the requested memory
1939       // region is taken already, for example, by 'java' launcher.
1940       // Try again to reserver heap higher.
1941       addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1942 
1943       ReservedHeapSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1944                                  UseLargePages, addr);
1945 
1946       if (addr != NULL && !heap_rs0.is_reserved()) {
1947         // Failed to reserve at specified address again - give up.
1948         addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1949         assert(addr == NULL, "");
1950 
1951         ReservedHeapSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1952                                    UseLargePages, addr);
1953         heap_rs = heap_rs1;
1954       } else {
1955         heap_rs = heap_rs0;
1956       }
1957     }
1958   }
1959 
1960   if (!heap_rs.is_reserved()) {
1961     vm_exit_during_initialization("Could not reserve enough space for object heap");
1962     return JNI_ENOMEM;
1963   }
1964 
1965   // It is important to do this in a way such that concurrent readers can't
1966   // temporarily think somethings in the heap.  (I've actually seen this
1967   // happen in asserts: DLD.)
1968   _reserved.set_word_size(0);
1969   _reserved.set_start((HeapWord*)heap_rs.base());
1970   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1971 
1972   _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1973 
1974   // Create the gen rem set (and barrier set) for the entire reserved region.
1975   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1976   set_barrier_set(rem_set()->bs());
1977   if (barrier_set()->is_a(BarrierSet::ModRef)) {
1978     _mr_bs = (ModRefBarrierSet*)_barrier_set;
1979   } else {
1980     vm_exit_during_initialization("G1 requires a mod ref bs.");
1981     return JNI_ENOMEM;
1982   }
1983 
1984   // Also create a G1 rem set.
1985   if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1986     _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
1987   } else {
1988     vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1989     return JNI_ENOMEM;
1990   }
1991 
1992   // Carve out the G1 part of the heap.
1993 
1994   ReservedSpace g1_rs   = heap_rs.first_part(max_byte_size);
1995   _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1996                            g1_rs.size()/HeapWordSize);
1997   ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1998 
1999   _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
2000 
2001   _g1_storage.initialize(g1_rs, 0);
2002   _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2003   _hrs.initialize((HeapWord*) _g1_reserved.start(),
2004                   (HeapWord*) _g1_reserved.end(),
2005                   _expansion_regions);
2006 
2007   // 6843694 - ensure that the maximum region index can fit
2008   // in the remembered set structures.
2009   const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2010   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2011 
2012   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2013   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2014   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2015             "too many cards per region");
2016 
2017   HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2018 
2019   _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2020                                              heap_word_size(init_byte_size));
2021 
2022   _g1h = this;
2023 
2024    _in_cset_fast_test_length = max_regions();
2025    _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
2026 
2027    // We're biasing _in_cset_fast_test to avoid subtracting the
2028    // beginning of the heap every time we want to index; basically
2029    // it's the same with what we do with the card table.
2030    _in_cset_fast_test = _in_cset_fast_test_base -
2031                 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2032 
2033    // Clear the _cset_fast_test bitmap in anticipation of adding
2034    // regions to the incremental collection set for the first
2035    // evacuation pause.
2036    clear_cset_fast_test();
2037 
2038   // Create the ConcurrentMark data structure and thread.
2039   // (Must do this late, so that "max_regions" is defined.)
2040   _cm       = new ConcurrentMark(heap_rs, (int) max_regions());
2041   _cmThread = _cm->cmThread();
2042 
2043   // Initialize the from_card cache structure of HeapRegionRemSet.
2044   HeapRegionRemSet::init_heap(max_regions());
2045 
2046   // Now expand into the initial heap size.
2047   if (!expand(init_byte_size)) {
2048     vm_exit_during_initialization("Failed to allocate initial heap.");
2049     return JNI_ENOMEM;
2050   }
2051 
2052   // Perform any initialization actions delegated to the policy.
2053   g1_policy()->init();
2054 
2055   _refine_cte_cl =
2056     new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2057                                     g1_rem_set(),
2058                                     concurrent_g1_refine());
2059   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2060 
2061   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2062                                                SATB_Q_FL_lock,
2063                                                G1SATBProcessCompletedThreshold,
2064                                                Shared_SATB_Q_lock);
2065 
2066   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2067                                                 DirtyCardQ_FL_lock,
2068                                                 concurrent_g1_refine()->yellow_zone(),
2069                                                 concurrent_g1_refine()->red_zone(),
2070                                                 Shared_DirtyCardQ_lock);
2071 
2072   if (G1DeferredRSUpdate) {
2073     dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2074                                       DirtyCardQ_FL_lock,
2075                                       -1, // never trigger processing
2076                                       -1, // no limit on length
2077                                       Shared_DirtyCardQ_lock,
2078                                       &JavaThread::dirty_card_queue_set());
2079   }
2080 
2081   // Initialize the card queue set used to hold cards containing
2082   // references into the collection set.
2083   _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2084                                              DirtyCardQ_FL_lock,
2085                                              -1, // never trigger processing
2086                                              -1, // no limit on length
2087                                              Shared_DirtyCardQ_lock,
2088                                              &JavaThread::dirty_card_queue_set());
2089 
2090   // In case we're keeping closure specialization stats, initialize those
2091   // counts and that mechanism.
2092   SpecializationStats::clear();
2093 
2094   // Do later initialization work for concurrent refinement.
2095   _cg1r->init();
2096 
2097   // Here we allocate the dummy full region that is required by the
2098   // G1AllocRegion class. If we don't pass an address in the reserved
2099   // space here, lots of asserts fire.
2100 
2101   HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2102                                              _g1_reserved.start());
2103   // We'll re-use the same region whether the alloc region will
2104   // require BOT updates or not and, if it doesn't, then a non-young
2105   // region will complain that it cannot support allocations without
2106   // BOT updates. So we'll tag the dummy region as young to avoid that.
2107   dummy_region->set_young();
2108   // Make sure it's full.
2109   dummy_region->set_top(dummy_region->end());
2110   G1AllocRegion::setup(this, dummy_region);
2111 
2112   init_mutator_alloc_region();
2113 
2114   // Do create of the monitoring and management support so that
2115   // values in the heap have been properly initialized.
2116   _g1mm = new G1MonitoringSupport(this);
2117 
2118   return JNI_OK;
2119 }
2120 
2121 void G1CollectedHeap::ref_processing_init() {
2122   // Reference processing in G1 currently works as follows:
2123   //
2124   // * There are two reference processor instances. One is
2125   //   used to record and process discovered references
2126   //   during concurrent marking; the other is used to
2127   //   record and process references during STW pauses
2128   //   (both full and incremental).
2129   // * Both ref processors need to 'span' the entire heap as
2130   //   the regions in the collection set may be dotted around.
2131   //
2132   // * For the concurrent marking ref processor:
2133   //   * Reference discovery is enabled at initial marking.
2134   //   * Reference discovery is disabled and the discovered
2135   //     references processed etc during remarking.
2136   //   * Reference discovery is MT (see below).
2137   //   * Reference discovery requires a barrier (see below).
2138   //   * Reference processing may or may not be MT
2139   //     (depending on the value of ParallelRefProcEnabled
2140   //     and ParallelGCThreads).
2141   //   * A full GC disables reference discovery by the CM
2142   //     ref processor and abandons any entries on it's
2143   //     discovered lists.
2144   //
2145   // * For the STW processor:
2146   //   * Non MT discovery is enabled at the start of a full GC.
2147   //   * Processing and enqueueing during a full GC is non-MT.
2148   //   * During a full GC, references are processed after marking.
2149   //
2150   //   * Discovery (may or may not be MT) is enabled at the start
2151   //     of an incremental evacuation pause.
2152   //   * References are processed near the end of a STW evacuation pause.
2153   //   * For both types of GC:
2154   //     * Discovery is atomic - i.e. not concurrent.
2155   //     * Reference discovery will not need a barrier.
2156 
2157   SharedHeap::ref_processing_init();
2158   MemRegion mr = reserved_region();
2159 
2160   // Concurrent Mark ref processor
2161   _ref_processor_cm =
2162     new ReferenceProcessor(mr,    // span
2163                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2164                                 // mt processing
2165                            (int) ParallelGCThreads,
2166                                 // degree of mt processing
2167                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2168                                 // mt discovery
2169                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2170                                 // degree of mt discovery
2171                            false,
2172                                 // Reference discovery is not atomic
2173                            &_is_alive_closure_cm,
2174                                 // is alive closure
2175                                 // (for efficiency/performance)
2176                            true);
2177                                 // Setting next fields of discovered
2178                                 // lists requires a barrier.
2179 
2180   // STW ref processor
2181   _ref_processor_stw =
2182     new ReferenceProcessor(mr,    // span
2183                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2184                                 // mt processing
2185                            MAX2((int)ParallelGCThreads, 1),
2186                                 // degree of mt processing
2187                            (ParallelGCThreads > 1),
2188                                 // mt discovery
2189                            MAX2((int)ParallelGCThreads, 1),
2190                                 // degree of mt discovery
2191                            true,
2192                                 // Reference discovery is atomic
2193                            &_is_alive_closure_stw,
2194                                 // is alive closure
2195                                 // (for efficiency/performance)
2196                            false);
2197                                 // Setting next fields of discovered
2198                                 // lists requires a barrier.
2199 }
2200 
2201 size_t G1CollectedHeap::capacity() const {
2202   return _g1_committed.byte_size();
2203 }
2204 
2205 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2206                                                  DirtyCardQueue* into_cset_dcq,
2207                                                  bool concurrent,
2208                                                  int worker_i) {
2209   // Clean cards in the hot card cache
2210   concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
2211 
2212   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2213   int n_completed_buffers = 0;
2214   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2215     n_completed_buffers++;
2216   }
2217   g1_policy()->record_update_rs_processed_buffers(worker_i,
2218                                                   (double) n_completed_buffers);
2219   dcqs.clear_n_completed_buffers();
2220   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2221 }
2222 
2223 
2224 // Computes the sum of the storage used by the various regions.
2225 
2226 size_t G1CollectedHeap::used() const {
2227   assert(Heap_lock->owner() != NULL,
2228          "Should be owned on this thread's behalf.");
2229   size_t result = _summary_bytes_used;
2230   // Read only once in case it is set to NULL concurrently
2231   HeapRegion* hr = _mutator_alloc_region.get();
2232   if (hr != NULL)
2233     result += hr->used();
2234   return result;
2235 }
2236 
2237 size_t G1CollectedHeap::used_unlocked() const {
2238   size_t result = _summary_bytes_used;
2239   return result;
2240 }
2241 
2242 class SumUsedClosure: public HeapRegionClosure {
2243   size_t _used;
2244 public:
2245   SumUsedClosure() : _used(0) {}
2246   bool doHeapRegion(HeapRegion* r) {
2247     if (!r->continuesHumongous()) {
2248       _used += r->used();
2249     }
2250     return false;
2251   }
2252   size_t result() { return _used; }
2253 };
2254 
2255 size_t G1CollectedHeap::recalculate_used() const {
2256   SumUsedClosure blk;
2257   heap_region_iterate(&blk);
2258   return blk.result();
2259 }
2260 
2261 size_t G1CollectedHeap::unsafe_max_alloc() {
2262   if (free_regions() > 0) return HeapRegion::GrainBytes;
2263   // otherwise, is there space in the current allocation region?
2264 
2265   // We need to store the current allocation region in a local variable
2266   // here. The problem is that this method doesn't take any locks and
2267   // there may be other threads which overwrite the current allocation
2268   // region field. attempt_allocation(), for example, sets it to NULL
2269   // and this can happen *after* the NULL check here but before the call
2270   // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2271   // to be a problem in the optimized build, since the two loads of the
2272   // current allocation region field are optimized away.
2273   HeapRegion* hr = _mutator_alloc_region.get();
2274   if (hr == NULL) {
2275     return 0;
2276   }
2277   return hr->free();
2278 }
2279 
2280 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2281   return
2282     ((cause == GCCause::_gc_locker           && GCLockerInvokesConcurrent) ||
2283      (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
2284 }
2285 
2286 #ifndef PRODUCT
2287 void G1CollectedHeap::allocate_dummy_regions() {
2288   // Let's fill up most of the region
2289   size_t word_size = HeapRegion::GrainWords - 1024;
2290   // And as a result the region we'll allocate will be humongous.
2291   guarantee(isHumongous(word_size), "sanity");
2292 
2293   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2294     // Let's use the existing mechanism for the allocation
2295     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2296     if (dummy_obj != NULL) {
2297       MemRegion mr(dummy_obj, word_size);
2298       CollectedHeap::fill_with_object(mr);
2299     } else {
2300       // If we can't allocate once, we probably cannot allocate
2301       // again. Let's get out of the loop.
2302       break;
2303     }
2304   }
2305 }
2306 #endif // !PRODUCT
2307 
2308 void G1CollectedHeap::increment_full_collections_completed(bool concurrent) {
2309   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2310 
2311   // We assume that if concurrent == true, then the caller is a
2312   // concurrent thread that was joined the Suspendible Thread
2313   // Set. If there's ever a cheap way to check this, we should add an
2314   // assert here.
2315 
2316   // We have already incremented _total_full_collections at the start
2317   // of the GC, so total_full_collections() represents how many full
2318   // collections have been started.
2319   unsigned int full_collections_started = total_full_collections();
2320 
2321   // Given that this method is called at the end of a Full GC or of a
2322   // concurrent cycle, and those can be nested (i.e., a Full GC can
2323   // interrupt a concurrent cycle), the number of full collections
2324   // completed should be either one (in the case where there was no
2325   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2326   // behind the number of full collections started.
2327 
2328   // This is the case for the inner caller, i.e. a Full GC.
2329   assert(concurrent ||
2330          (full_collections_started == _full_collections_completed + 1) ||
2331          (full_collections_started == _full_collections_completed + 2),
2332          err_msg("for inner caller (Full GC): full_collections_started = %u "
2333                  "is inconsistent with _full_collections_completed = %u",
2334                  full_collections_started, _full_collections_completed));
2335 
2336   // This is the case for the outer caller, i.e. the concurrent cycle.
2337   assert(!concurrent ||
2338          (full_collections_started == _full_collections_completed + 1),
2339          err_msg("for outer caller (concurrent cycle): "
2340                  "full_collections_started = %u "
2341                  "is inconsistent with _full_collections_completed = %u",
2342                  full_collections_started, _full_collections_completed));
2343 
2344   _full_collections_completed += 1;
2345 
2346   // We need to clear the "in_progress" flag in the CM thread before
2347   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2348   // is set) so that if a waiter requests another System.gc() it doesn't
2349   // incorrectly see that a marking cyle is still in progress.
2350   if (concurrent) {
2351     _cmThread->clear_in_progress();
2352   }
2353 
2354   // This notify_all() will ensure that a thread that called
2355   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2356   // and it's waiting for a full GC to finish will be woken up. It is
2357   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2358   FullGCCount_lock->notify_all();
2359 }
2360 
2361 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
2362   assert_at_safepoint(true /* should_be_vm_thread */);
2363   GCCauseSetter gcs(this, cause);
2364   switch (cause) {
2365     case GCCause::_heap_inspection:
2366     case GCCause::_heap_dump: {
2367       HandleMark hm;
2368       do_full_collection(false);         // don't clear all soft refs
2369       break;
2370     }
2371     default: // XXX FIX ME
2372       ShouldNotReachHere(); // Unexpected use of this function
2373   }
2374 }
2375 
2376 void G1CollectedHeap::collect(GCCause::Cause cause) {
2377   // The caller doesn't have the Heap_lock
2378   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
2379 
2380   unsigned int gc_count_before;
2381   unsigned int full_gc_count_before;
2382   {
2383     MutexLocker ml(Heap_lock);
2384 
2385     // Read the GC count while holding the Heap_lock
2386     gc_count_before = SharedHeap::heap()->total_collections();
2387     full_gc_count_before = SharedHeap::heap()->total_full_collections();
2388   }
2389 
2390   if (should_do_concurrent_full_gc(cause)) {
2391     // Schedule an initial-mark evacuation pause that will start a
2392     // concurrent cycle. We're setting word_size to 0 which means that
2393     // we are not requesting a post-GC allocation.
2394     VM_G1IncCollectionPause op(gc_count_before,
2395                                0,     /* word_size */
2396                                true,  /* should_initiate_conc_mark */
2397                                g1_policy()->max_pause_time_ms(),
2398                                cause);
2399     VMThread::execute(&op);
2400   } else {
2401     if (cause == GCCause::_gc_locker
2402         DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2403 
2404       // Schedule a standard evacuation pause. We're setting word_size
2405       // to 0 which means that we are not requesting a post-GC allocation.
2406       VM_G1IncCollectionPause op(gc_count_before,
2407                                  0,     /* word_size */
2408                                  false, /* should_initiate_conc_mark */
2409                                  g1_policy()->max_pause_time_ms(),
2410                                  cause);
2411       VMThread::execute(&op);
2412     } else {
2413       // Schedule a Full GC.
2414       VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2415       VMThread::execute(&op);
2416     }
2417   }
2418 }
2419 
2420 bool G1CollectedHeap::is_in(const void* p) const {
2421   if (_g1_committed.contains(p)) {
2422     // Given that we know that p is in the committed space,
2423     // heap_region_containing_raw() should successfully
2424     // return the containing region.
2425     HeapRegion* hr = heap_region_containing_raw(p);
2426     return hr->is_in(p);
2427   } else {
2428     return _perm_gen->as_gen()->is_in(p);
2429   }
2430 }
2431 
2432 // Iteration functions.
2433 
2434 // Iterates an OopClosure over all ref-containing fields of objects
2435 // within a HeapRegion.
2436 
2437 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2438   MemRegion _mr;
2439   OopClosure* _cl;
2440 public:
2441   IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
2442     : _mr(mr), _cl(cl) {}
2443   bool doHeapRegion(HeapRegion* r) {
2444     if (! r->continuesHumongous()) {
2445       r->oop_iterate(_cl);
2446     }
2447     return false;
2448   }
2449 };
2450 
2451 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
2452   IterateOopClosureRegionClosure blk(_g1_committed, cl);
2453   heap_region_iterate(&blk);
2454   if (do_perm) {
2455     perm_gen()->oop_iterate(cl);
2456   }
2457 }
2458 
2459 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
2460   IterateOopClosureRegionClosure blk(mr, cl);
2461   heap_region_iterate(&blk);
2462   if (do_perm) {
2463     perm_gen()->oop_iterate(cl);
2464   }
2465 }
2466 
2467 // Iterates an ObjectClosure over all objects within a HeapRegion.
2468 
2469 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2470   ObjectClosure* _cl;
2471 public:
2472   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2473   bool doHeapRegion(HeapRegion* r) {
2474     if (! r->continuesHumongous()) {
2475       r->object_iterate(_cl);
2476     }
2477     return false;
2478   }
2479 };
2480 
2481 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
2482   IterateObjectClosureRegionClosure blk(cl);
2483   heap_region_iterate(&blk);
2484   if (do_perm) {
2485     perm_gen()->object_iterate(cl);
2486   }
2487 }
2488 
2489 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2490   // FIXME: is this right?
2491   guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2492 }
2493 
2494 // Calls a SpaceClosure on a HeapRegion.
2495 
2496 class SpaceClosureRegionClosure: public HeapRegionClosure {
2497   SpaceClosure* _cl;
2498 public:
2499   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2500   bool doHeapRegion(HeapRegion* r) {
2501     _cl->do_space(r);
2502     return false;
2503   }
2504 };
2505 
2506 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2507   SpaceClosureRegionClosure blk(cl);
2508   heap_region_iterate(&blk);
2509 }
2510 
2511 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2512   _hrs.iterate(cl);
2513 }
2514 
2515 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
2516                                                HeapRegionClosure* cl) const {
2517   _hrs.iterate_from(r, cl);
2518 }
2519 
2520 void
2521 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2522                                                  int worker,
2523                                                  int no_of_par_workers,
2524                                                  jint claim_value) {
2525   const size_t regions = n_regions();
2526   const size_t max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2527                              no_of_par_workers :
2528                              1);
2529   assert(UseDynamicNumberOfGCThreads ||
2530          no_of_par_workers == workers()->total_workers(),
2531          "Non dynamic should use fixed number of workers");
2532   // try to spread out the starting points of the workers
2533   const size_t start_index = regions / max_workers * (size_t) worker;
2534 
2535   // each worker will actually look at all regions
2536   for (size_t count = 0; count < regions; ++count) {
2537     const size_t index = (start_index + count) % regions;
2538     assert(0 <= index && index < regions, "sanity");
2539     HeapRegion* r = region_at(index);
2540     // we'll ignore "continues humongous" regions (we'll process them
2541     // when we come across their corresponding "start humongous"
2542     // region) and regions already claimed
2543     if (r->claim_value() == claim_value || r->continuesHumongous()) {
2544       continue;
2545     }
2546     // OK, try to claim it
2547     if (r->claimHeapRegion(claim_value)) {
2548       // success!
2549       assert(!r->continuesHumongous(), "sanity");
2550       if (r->startsHumongous()) {
2551         // If the region is "starts humongous" we'll iterate over its
2552         // "continues humongous" first; in fact we'll do them
2553         // first. The order is important. In on case, calling the
2554         // closure on the "starts humongous" region might de-allocate
2555         // and clear all its "continues humongous" regions and, as a
2556         // result, we might end up processing them twice. So, we'll do
2557         // them first (notice: most closures will ignore them anyway) and
2558         // then we'll do the "starts humongous" region.
2559         for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
2560           HeapRegion* chr = region_at(ch_index);
2561 
2562           // if the region has already been claimed or it's not
2563           // "continues humongous" we're done
2564           if (chr->claim_value() == claim_value ||
2565               !chr->continuesHumongous()) {
2566             break;
2567           }
2568 
2569           // Noone should have claimed it directly. We can given
2570           // that we claimed its "starts humongous" region.
2571           assert(chr->claim_value() != claim_value, "sanity");
2572           assert(chr->humongous_start_region() == r, "sanity");
2573 
2574           if (chr->claimHeapRegion(claim_value)) {
2575             // we should always be able to claim it; noone else should
2576             // be trying to claim this region
2577 
2578             bool res2 = cl->doHeapRegion(chr);
2579             assert(!res2, "Should not abort");
2580 
2581             // Right now, this holds (i.e., no closure that actually
2582             // does something with "continues humongous" regions
2583             // clears them). We might have to weaken it in the future,
2584             // but let's leave these two asserts here for extra safety.
2585             assert(chr->continuesHumongous(), "should still be the case");
2586             assert(chr->humongous_start_region() == r, "sanity");
2587           } else {
2588             guarantee(false, "we should not reach here");
2589           }
2590         }
2591       }
2592 
2593       assert(!r->continuesHumongous(), "sanity");
2594       bool res = cl->doHeapRegion(r);
2595       assert(!res, "Should not abort");
2596     }
2597   }
2598 }
2599 
2600 class ResetClaimValuesClosure: public HeapRegionClosure {
2601 public:
2602   bool doHeapRegion(HeapRegion* r) {
2603     r->set_claim_value(HeapRegion::InitialClaimValue);
2604     return false;
2605   }
2606 };
2607 
2608 void
2609 G1CollectedHeap::reset_heap_region_claim_values() {
2610   ResetClaimValuesClosure blk;
2611   heap_region_iterate(&blk);
2612 }
2613 
2614 #ifdef ASSERT
2615 // This checks whether all regions in the heap have the correct claim
2616 // value. I also piggy-backed on this a check to ensure that the
2617 // humongous_start_region() information on "continues humongous"
2618 // regions is correct.
2619 
2620 class CheckClaimValuesClosure : public HeapRegionClosure {
2621 private:
2622   jint _claim_value;
2623   size_t _failures;
2624   HeapRegion* _sh_region;
2625 public:
2626   CheckClaimValuesClosure(jint claim_value) :
2627     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2628   bool doHeapRegion(HeapRegion* r) {
2629     if (r->claim_value() != _claim_value) {
2630       gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2631                              "claim value = %d, should be %d",
2632                              HR_FORMAT_PARAMS(r),
2633                              r->claim_value(), _claim_value);
2634       ++_failures;
2635     }
2636     if (!r->isHumongous()) {
2637       _sh_region = NULL;
2638     } else if (r->startsHumongous()) {
2639       _sh_region = r;
2640     } else if (r->continuesHumongous()) {
2641       if (r->humongous_start_region() != _sh_region) {
2642         gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2643                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2644                                HR_FORMAT_PARAMS(r),
2645                                r->humongous_start_region(),
2646                                _sh_region);
2647         ++_failures;
2648       }
2649     }
2650     return false;
2651   }
2652   size_t failures() {
2653     return _failures;
2654   }
2655 };
2656 
2657 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2658   CheckClaimValuesClosure cl(claim_value);
2659   heap_region_iterate(&cl);
2660   return cl.failures() == 0;
2661 }
2662 
2663 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2664   jint   _claim_value;
2665   size_t _failures;
2666 
2667 public:
2668   CheckClaimValuesInCSetHRClosure(jint claim_value) :
2669     _claim_value(claim_value),
2670     _failures(0) { }
2671 
2672   size_t failures() {
2673     return _failures;
2674   }
2675 
2676   bool doHeapRegion(HeapRegion* hr) {
2677     assert(hr->in_collection_set(), "how?");
2678     assert(!hr->isHumongous(), "H-region in CSet");
2679     if (hr->claim_value() != _claim_value) {
2680       gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2681                              "claim value = %d, should be %d",
2682                              HR_FORMAT_PARAMS(hr),
2683                              hr->claim_value(), _claim_value);
2684       _failures += 1;
2685     }
2686     return false;
2687   }
2688 };
2689 
2690 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2691   CheckClaimValuesInCSetHRClosure cl(claim_value);
2692   collection_set_iterate(&cl);
2693   return cl.failures() == 0;
2694 }
2695 #endif // ASSERT
2696 
2697 // Clear the cached CSet starting regions and (more importantly)
2698 // the time stamps. Called when we reset the GC time stamp.
2699 void G1CollectedHeap::clear_cset_start_regions() {
2700   assert(_worker_cset_start_region != NULL, "sanity");
2701   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2702 
2703   int n_queues = MAX2((int)ParallelGCThreads, 1);
2704   for (int i = 0; i < n_queues; i++) {
2705     _worker_cset_start_region[i] = NULL;
2706     _worker_cset_start_region_time_stamp[i] = 0;
2707   }
2708 }
2709 
2710 // Given the id of a worker, obtain or calculate a suitable
2711 // starting region for iterating over the current collection set.
2712 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2713   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2714 
2715   HeapRegion* result = NULL;
2716   unsigned gc_time_stamp = get_gc_time_stamp();
2717 
2718   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2719     // Cached starting region for current worker was set
2720     // during the current pause - so it's valid.
2721     // Note: the cached starting heap region may be NULL
2722     // (when the collection set is empty).
2723     result = _worker_cset_start_region[worker_i];
2724     assert(result == NULL || result->in_collection_set(), "sanity");
2725     return result;
2726   }
2727 
2728   // The cached entry was not valid so let's calculate
2729   // a suitable starting heap region for this worker.
2730 
2731   // We want the parallel threads to start their collection
2732   // set iteration at different collection set regions to
2733   // avoid contention.
2734   // If we have:
2735   //          n collection set regions
2736   //          p threads
2737   // Then thread t will start at region floor ((t * n) / p)
2738 
2739   result = g1_policy()->collection_set();
2740   if (G1CollectedHeap::use_parallel_gc_threads()) {
2741     size_t cs_size = g1_policy()->cset_region_length();
2742     int active_workers = workers()->active_workers();
2743     assert(UseDynamicNumberOfGCThreads ||
2744              active_workers == workers()->total_workers(),
2745              "Unless dynamic should use total workers");
2746 
2747     size_t end_ind   = (cs_size * worker_i) / active_workers;
2748     size_t start_ind = 0;
2749 
2750     if (worker_i > 0 &&
2751         _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2752       // Previous workers starting region is valid
2753       // so let's iterate from there
2754       start_ind = (cs_size * (worker_i - 1)) / active_workers;
2755       result = _worker_cset_start_region[worker_i - 1];
2756     }
2757 
2758     for (size_t i = start_ind; i < end_ind; i++) {
2759       result = result->next_in_collection_set();
2760     }
2761   }
2762 
2763   // Note: the calculated starting heap region may be NULL
2764   // (when the collection set is empty).
2765   assert(result == NULL || result->in_collection_set(), "sanity");
2766   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2767          "should be updated only once per pause");
2768   _worker_cset_start_region[worker_i] = result;
2769   OrderAccess::storestore();
2770   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2771   return result;
2772 }
2773 
2774 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2775   HeapRegion* r = g1_policy()->collection_set();
2776   while (r != NULL) {
2777     HeapRegion* next = r->next_in_collection_set();
2778     if (cl->doHeapRegion(r)) {
2779       cl->incomplete();
2780       return;
2781     }
2782     r = next;
2783   }
2784 }
2785 
2786 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2787                                                   HeapRegionClosure *cl) {
2788   if (r == NULL) {
2789     // The CSet is empty so there's nothing to do.
2790     return;
2791   }
2792 
2793   assert(r->in_collection_set(),
2794          "Start region must be a member of the collection set.");
2795   HeapRegion* cur = r;
2796   while (cur != NULL) {
2797     HeapRegion* next = cur->next_in_collection_set();
2798     if (cl->doHeapRegion(cur) && false) {
2799       cl->incomplete();
2800       return;
2801     }
2802     cur = next;
2803   }
2804   cur = g1_policy()->collection_set();
2805   while (cur != r) {
2806     HeapRegion* next = cur->next_in_collection_set();
2807     if (cl->doHeapRegion(cur) && false) {
2808       cl->incomplete();
2809       return;
2810     }
2811     cur = next;
2812   }
2813 }
2814 
2815 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2816   return n_regions() > 0 ? region_at(0) : NULL;
2817 }
2818 
2819 
2820 Space* G1CollectedHeap::space_containing(const void* addr) const {
2821   Space* res = heap_region_containing(addr);
2822   if (res == NULL)
2823     res = perm_gen()->space_containing(addr);
2824   return res;
2825 }
2826 
2827 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2828   Space* sp = space_containing(addr);
2829   if (sp != NULL) {
2830     return sp->block_start(addr);
2831   }
2832   return NULL;
2833 }
2834 
2835 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2836   Space* sp = space_containing(addr);
2837   assert(sp != NULL, "block_size of address outside of heap");
2838   return sp->block_size(addr);
2839 }
2840 
2841 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2842   Space* sp = space_containing(addr);
2843   return sp->block_is_obj(addr);
2844 }
2845 
2846 bool G1CollectedHeap::supports_tlab_allocation() const {
2847   return true;
2848 }
2849 
2850 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2851   return HeapRegion::GrainBytes;
2852 }
2853 
2854 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2855   // Return the remaining space in the cur alloc region, but not less than
2856   // the min TLAB size.
2857 
2858   // Also, this value can be at most the humongous object threshold,
2859   // since we can't allow tlabs to grow big enough to accomodate
2860   // humongous objects.
2861 
2862   HeapRegion* hr = _mutator_alloc_region.get();
2863   size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2864   if (hr == NULL) {
2865     return max_tlab_size;
2866   } else {
2867     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
2868   }
2869 }
2870 
2871 size_t G1CollectedHeap::max_capacity() const {
2872   return _g1_reserved.byte_size();
2873 }
2874 
2875 jlong G1CollectedHeap::millis_since_last_gc() {
2876   // assert(false, "NYI");
2877   return 0;
2878 }
2879 
2880 void G1CollectedHeap::prepare_for_verify() {
2881   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2882     ensure_parsability(false);
2883   }
2884   g1_rem_set()->prepare_for_verify();
2885 }
2886 
2887 class VerifyLivenessOopClosure: public OopClosure {
2888   G1CollectedHeap* _g1h;
2889   VerifyOption _vo;
2890 public:
2891   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2892     _g1h(g1h), _vo(vo)
2893   { }
2894   void do_oop(narrowOop *p) { do_oop_work(p); }
2895   void do_oop(      oop *p) { do_oop_work(p); }
2896 
2897   template <class T> void do_oop_work(T *p) {
2898     oop obj = oopDesc::load_decode_heap_oop(p);
2899     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2900               "Dead object referenced by a not dead object");
2901   }
2902 };
2903 
2904 class VerifyObjsInRegionClosure: public ObjectClosure {
2905 private:
2906   G1CollectedHeap* _g1h;
2907   size_t _live_bytes;
2908   HeapRegion *_hr;
2909   VerifyOption _vo;
2910 public:
2911   // _vo == UsePrevMarking -> use "prev" marking information,
2912   // _vo == UseNextMarking -> use "next" marking information,
2913   // _vo == UseMarkWord    -> use mark word from object header.
2914   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2915     : _live_bytes(0), _hr(hr), _vo(vo) {
2916     _g1h = G1CollectedHeap::heap();
2917   }
2918   void do_object(oop o) {
2919     VerifyLivenessOopClosure isLive(_g1h, _vo);
2920     assert(o != NULL, "Huh?");
2921     if (!_g1h->is_obj_dead_cond(o, _vo)) {
2922       // If the object is alive according to the mark word,
2923       // then verify that the marking information agrees.
2924       // Note we can't verify the contra-positive of the
2925       // above: if the object is dead (according to the mark
2926       // word), it may not be marked, or may have been marked
2927       // but has since became dead, or may have been allocated
2928       // since the last marking.
2929       if (_vo == VerifyOption_G1UseMarkWord) {
2930         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2931       }
2932 
2933       o->oop_iterate(&isLive);
2934       if (!_hr->obj_allocated_since_prev_marking(o)) {
2935         size_t obj_size = o->size();    // Make sure we don't overflow
2936         _live_bytes += (obj_size * HeapWordSize);
2937       }
2938     }
2939   }
2940   size_t live_bytes() { return _live_bytes; }
2941 };
2942 
2943 class PrintObjsInRegionClosure : public ObjectClosure {
2944   HeapRegion *_hr;
2945   G1CollectedHeap *_g1;
2946 public:
2947   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2948     _g1 = G1CollectedHeap::heap();
2949   };
2950 
2951   void do_object(oop o) {
2952     if (o != NULL) {
2953       HeapWord *start = (HeapWord *) o;
2954       size_t word_sz = o->size();
2955       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2956                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2957                           (void*) o, word_sz,
2958                           _g1->isMarkedPrev(o),
2959                           _g1->isMarkedNext(o),
2960                           _hr->obj_allocated_since_prev_marking(o));
2961       HeapWord *end = start + word_sz;
2962       HeapWord *cur;
2963       int *val;
2964       for (cur = start; cur < end; cur++) {
2965         val = (int *) cur;
2966         gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2967       }
2968     }
2969   }
2970 };
2971 
2972 class VerifyRegionClosure: public HeapRegionClosure {
2973 private:
2974   bool         _allow_dirty;
2975   bool         _par;
2976   VerifyOption _vo;
2977   bool         _failures;
2978 public:
2979   // _vo == UsePrevMarking -> use "prev" marking information,
2980   // _vo == UseNextMarking -> use "next" marking information,
2981   // _vo == UseMarkWord    -> use mark word from object header.
2982   VerifyRegionClosure(bool allow_dirty, bool par, VerifyOption vo)
2983     : _allow_dirty(allow_dirty),
2984       _par(par),
2985       _vo(vo),
2986       _failures(false) {}
2987 
2988   bool failures() {
2989     return _failures;
2990   }
2991 
2992   bool doHeapRegion(HeapRegion* r) {
2993     guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2994               "Should be unclaimed at verify points.");
2995     if (!r->continuesHumongous()) {
2996       bool failures = false;
2997       r->verify(_allow_dirty, _vo, &failures);
2998       if (failures) {
2999         _failures = true;
3000       } else {
3001         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3002         r->object_iterate(&not_dead_yet_cl);
3003         if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3004           gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3005                                  "max_live_bytes "SIZE_FORMAT" "
3006                                  "< calculated "SIZE_FORMAT,
3007                                  r->bottom(), r->end(),
3008                                  r->max_live_bytes(),
3009                                  not_dead_yet_cl.live_bytes());
3010           _failures = true;
3011         }
3012       }
3013     }
3014     return false; // stop the region iteration if we hit a failure
3015   }
3016 };
3017 
3018 class VerifyRootsClosure: public OopsInGenClosure {
3019 private:
3020   G1CollectedHeap* _g1h;
3021   VerifyOption     _vo;
3022   bool             _failures;
3023 public:
3024   // _vo == UsePrevMarking -> use "prev" marking information,
3025   // _vo == UseNextMarking -> use "next" marking information,
3026   // _vo == UseMarkWord    -> use mark word from object header.
3027   VerifyRootsClosure(VerifyOption vo) :
3028     _g1h(G1CollectedHeap::heap()),
3029     _vo(vo),
3030     _failures(false) { }
3031 
3032   bool failures() { return _failures; }
3033 
3034   template <class T> void do_oop_nv(T* p) {
3035     T heap_oop = oopDesc::load_heap_oop(p);
3036     if (!oopDesc::is_null(heap_oop)) {
3037       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3038       if (_g1h->is_obj_dead_cond(obj, _vo)) {
3039         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3040                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
3041         if (_vo == VerifyOption_G1UseMarkWord) {
3042           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3043         }
3044         obj->print_on(gclog_or_tty);
3045         _failures = true;
3046       }
3047     }
3048   }
3049 
3050   void do_oop(oop* p)       { do_oop_nv(p); }
3051   void do_oop(narrowOop* p) { do_oop_nv(p); }
3052 };
3053 
3054 // This is the task used for parallel heap verification.
3055 
3056 class G1ParVerifyTask: public AbstractGangTask {
3057 private:
3058   G1CollectedHeap* _g1h;
3059   bool             _allow_dirty;
3060   VerifyOption     _vo;
3061   bool             _failures;
3062 
3063 public:
3064   // _vo == UsePrevMarking -> use "prev" marking information,
3065   // _vo == UseNextMarking -> use "next" marking information,
3066   // _vo == UseMarkWord    -> use mark word from object header.
3067   G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty, VerifyOption vo) :
3068     AbstractGangTask("Parallel verify task"),
3069     _g1h(g1h),
3070     _allow_dirty(allow_dirty),
3071     _vo(vo),
3072     _failures(false) { }
3073 
3074   bool failures() {
3075     return _failures;
3076   }
3077 
3078   void work(int worker_i) {
3079     HandleMark hm;
3080     VerifyRegionClosure blk(_allow_dirty, true, _vo);
3081     _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
3082                                           _g1h->workers()->active_workers(),
3083                                           HeapRegion::ParVerifyClaimValue);
3084     if (blk.failures()) {
3085       _failures = true;
3086     }
3087   }
3088 };
3089 
3090 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
3091   verify(allow_dirty, silent, VerifyOption_G1UsePrevMarking);
3092 }
3093 
3094 void G1CollectedHeap::verify(bool allow_dirty,
3095                              bool silent,
3096                              VerifyOption vo) {
3097   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3098     if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); }
3099     VerifyRootsClosure rootsCl(vo);
3100 
3101     assert(Thread::current()->is_VM_thread(),
3102       "Expected to be executed serially by the VM thread at this point");
3103 
3104     CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
3105 
3106     // We apply the relevant closures to all the oops in the
3107     // system dictionary, the string table and the code cache.
3108     const int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
3109 
3110     process_strong_roots(true,      // activate StrongRootsScope
3111                          true,      // we set "collecting perm gen" to true,
3112                                     // so we don't reset the dirty cards in the perm gen.
3113                          SharedHeap::ScanningOption(so),  // roots scanning options
3114                          &rootsCl,
3115                          &blobsCl,
3116                          &rootsCl);
3117 
3118     // If we're verifying after the marking phase of a Full GC then we can't
3119     // treat the perm gen as roots into the G1 heap. Some of the objects in
3120     // the perm gen may be dead and hence not marked. If one of these dead
3121     // objects is considered to be a root then we may end up with a false
3122     // "Root location <x> points to dead ob <y>" failure.
3123     if (vo != VerifyOption_G1UseMarkWord) {
3124       // Since we used "collecting_perm_gen" == true above, we will not have
3125       // checked the refs from perm into the G1-collected heap. We check those
3126       // references explicitly below. Whether the relevant cards are dirty
3127       // is checked further below in the rem set verification.
3128       if (!silent) { gclog_or_tty->print("Permgen roots "); }
3129       perm_gen()->oop_iterate(&rootsCl);
3130     }
3131     bool failures = rootsCl.failures();
3132 
3133     if (vo != VerifyOption_G1UseMarkWord) {
3134       // If we're verifying during a full GC then the region sets
3135       // will have been torn down at the start of the GC. Therefore
3136       // verifying the region sets will fail. So we only verify
3137       // the region sets when not in a full GC.
3138       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3139       verify_region_sets();
3140     }
3141 
3142     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3143     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3144       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3145              "sanity check");
3146 
3147       G1ParVerifyTask task(this, allow_dirty, vo);
3148       assert(UseDynamicNumberOfGCThreads ||
3149         workers()->active_workers() == workers()->total_workers(),
3150         "If not dynamic should be using all the workers");
3151       int n_workers = workers()->active_workers();
3152       set_par_threads(n_workers);
3153       workers()->run_task(&task);
3154       set_par_threads(0);
3155       if (task.failures()) {
3156         failures = true;
3157       }
3158 
3159       // Checks that the expected amount of parallel work was done.
3160       // The implication is that n_workers is > 0.
3161       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3162              "sanity check");
3163 
3164       reset_heap_region_claim_values();
3165 
3166       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3167              "sanity check");
3168     } else {
3169       VerifyRegionClosure blk(allow_dirty, false, vo);
3170       heap_region_iterate(&blk);
3171       if (blk.failures()) {
3172         failures = true;
3173       }
3174     }
3175     if (!silent) gclog_or_tty->print("RemSet ");
3176     rem_set()->verify();
3177 
3178     if (failures) {
3179       gclog_or_tty->print_cr("Heap:");
3180       // It helps to have the per-region information in the output to
3181       // help us track down what went wrong. This is why we call
3182       // print_extended_on() instead of print_on().
3183       print_extended_on(gclog_or_tty);
3184       gclog_or_tty->print_cr("");
3185 #ifndef PRODUCT
3186       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3187         concurrent_mark()->print_reachable("at-verification-failure",
3188                                            vo, false /* all */);
3189       }
3190 #endif
3191       gclog_or_tty->flush();
3192     }
3193     guarantee(!failures, "there should not have been any failures");
3194   } else {
3195     if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
3196   }
3197 }
3198 
3199 class PrintRegionClosure: public HeapRegionClosure {
3200   outputStream* _st;
3201 public:
3202   PrintRegionClosure(outputStream* st) : _st(st) {}
3203   bool doHeapRegion(HeapRegion* r) {
3204     r->print_on(_st);
3205     return false;
3206   }
3207 };
3208 
3209 void G1CollectedHeap::print_on(outputStream* st) const {
3210   st->print(" %-20s", "garbage-first heap");
3211   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3212             capacity()/K, used_unlocked()/K);
3213   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3214             _g1_storage.low_boundary(),
3215             _g1_storage.high(),
3216             _g1_storage.high_boundary());
3217   st->cr();
3218   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3219   size_t young_regions = _young_list->length();
3220   st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
3221             young_regions, young_regions * HeapRegion::GrainBytes / K);
3222   size_t survivor_regions = g1_policy()->recorded_survivor_regions();
3223   st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
3224             survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
3225   st->cr();
3226   perm()->as_gen()->print_on(st);
3227 }
3228 
3229 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3230   print_on(st);
3231 
3232   // Print the per-region information.
3233   st->cr();
3234   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), HS=humongous(starts), HC=humongous(continues), CS=collection set, F=free, TS=gc time stamp, PTAMS=previous top-at-mark-start, NTAMS=next top-at-mark-start)");
3235   PrintRegionClosure blk(st);
3236   heap_region_iterate(&blk);
3237 }
3238 
3239 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3240   if (G1CollectedHeap::use_parallel_gc_threads()) {
3241     workers()->print_worker_threads_on(st);
3242   }
3243   _cmThread->print_on(st);
3244   st->cr();
3245   _cm->print_worker_threads_on(st);
3246   _cg1r->print_worker_threads_on(st);
3247   st->cr();
3248 }
3249 
3250 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3251   if (G1CollectedHeap::use_parallel_gc_threads()) {
3252     workers()->threads_do(tc);
3253   }
3254   tc->do_thread(_cmThread);
3255   _cg1r->threads_do(tc);
3256 }
3257 
3258 void G1CollectedHeap::print_tracing_info() const {
3259   // We'll overload this to mean "trace GC pause statistics."
3260   if (TraceGen0Time || TraceGen1Time) {
3261     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3262     // to that.
3263     g1_policy()->print_tracing_info();
3264   }
3265   if (G1SummarizeRSetStats) {
3266     g1_rem_set()->print_summary_info();
3267   }
3268   if (G1SummarizeConcMark) {
3269     concurrent_mark()->print_summary_info();
3270   }
3271   g1_policy()->print_yg_surv_rate_info();
3272   SpecializationStats::print();
3273 }
3274 
3275 #ifndef PRODUCT
3276 // Helpful for debugging RSet issues.
3277 
3278 class PrintRSetsClosure : public HeapRegionClosure {
3279 private:
3280   const char* _msg;
3281   size_t _occupied_sum;
3282 
3283 public:
3284   bool doHeapRegion(HeapRegion* r) {
3285     HeapRegionRemSet* hrrs = r->rem_set();
3286     size_t occupied = hrrs->occupied();
3287     _occupied_sum += occupied;
3288 
3289     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3290                            HR_FORMAT_PARAMS(r));
3291     if (occupied == 0) {
3292       gclog_or_tty->print_cr("  RSet is empty");
3293     } else {
3294       hrrs->print();
3295     }
3296     gclog_or_tty->print_cr("----------");
3297     return false;
3298   }
3299 
3300   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3301     gclog_or_tty->cr();
3302     gclog_or_tty->print_cr("========================================");
3303     gclog_or_tty->print_cr(msg);
3304     gclog_or_tty->cr();
3305   }
3306 
3307   ~PrintRSetsClosure() {
3308     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3309     gclog_or_tty->print_cr("========================================");
3310     gclog_or_tty->cr();
3311   }
3312 };
3313 
3314 void G1CollectedHeap::print_cset_rsets() {
3315   PrintRSetsClosure cl("Printing CSet RSets");
3316   collection_set_iterate(&cl);
3317 }
3318 
3319 void G1CollectedHeap::print_all_rsets() {
3320   PrintRSetsClosure cl("Printing All RSets");;
3321   heap_region_iterate(&cl);
3322 }
3323 #endif // PRODUCT
3324 
3325 G1CollectedHeap* G1CollectedHeap::heap() {
3326   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3327          "not a garbage-first heap");
3328   return _g1h;
3329 }
3330 
3331 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3332   // always_do_update_barrier = false;
3333   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3334   // Call allocation profiler
3335   AllocationProfiler::iterate_since_last_gc();
3336   // Fill TLAB's and such
3337   ensure_parsability(true);
3338 }
3339 
3340 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3341   // FIXME: what is this about?
3342   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3343   // is set.
3344   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3345                         "derived pointer present"));
3346   // always_do_update_barrier = true;
3347 
3348   // We have just completed a GC. Update the soft reference
3349   // policy with the new heap occupancy
3350   Universe::update_heap_info_at_gc();
3351 }
3352 
3353 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3354                                                unsigned int gc_count_before,
3355                                                bool* succeeded) {
3356   assert_heap_not_locked_and_not_at_safepoint();
3357   g1_policy()->record_stop_world_start();
3358   VM_G1IncCollectionPause op(gc_count_before,
3359                              word_size,
3360                              false, /* should_initiate_conc_mark */
3361                              g1_policy()->max_pause_time_ms(),
3362                              GCCause::_g1_inc_collection_pause);
3363   VMThread::execute(&op);
3364 
3365   HeapWord* result = op.result();
3366   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3367   assert(result == NULL || ret_succeeded,
3368          "the result should be NULL if the VM did not succeed");
3369   *succeeded = ret_succeeded;
3370 
3371   assert_heap_not_locked();
3372   return result;
3373 }
3374 
3375 void
3376 G1CollectedHeap::doConcurrentMark() {
3377   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3378   if (!_cmThread->in_progress()) {
3379     _cmThread->set_started();
3380     CGC_lock->notify();
3381   }
3382 }
3383 
3384 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
3385                                                        bool young) {
3386   return _g1_policy->predict_region_elapsed_time_ms(hr, young);
3387 }
3388 
3389 void G1CollectedHeap::check_if_region_is_too_expensive(double
3390                                                            predicted_time_ms) {
3391   _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
3392 }
3393 
3394 size_t G1CollectedHeap::pending_card_num() {
3395   size_t extra_cards = 0;
3396   JavaThread *curr = Threads::first();
3397   while (curr != NULL) {
3398     DirtyCardQueue& dcq = curr->dirty_card_queue();
3399     extra_cards += dcq.size();
3400     curr = curr->next();
3401   }
3402   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3403   size_t buffer_size = dcqs.buffer_size();
3404   size_t buffer_num = dcqs.completed_buffers_num();
3405   return buffer_size * buffer_num + extra_cards;
3406 }
3407 
3408 size_t G1CollectedHeap::max_pending_card_num() {
3409   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3410   size_t buffer_size = dcqs.buffer_size();
3411   size_t buffer_num  = dcqs.completed_buffers_num();
3412   int thread_num  = Threads::number_of_threads();
3413   return (buffer_num + thread_num) * buffer_size;
3414 }
3415 
3416 size_t G1CollectedHeap::cards_scanned() {
3417   return g1_rem_set()->cardsScanned();
3418 }
3419 
3420 void
3421 G1CollectedHeap::setup_surviving_young_words() {
3422   guarantee( _surviving_young_words == NULL, "pre-condition" );
3423   size_t array_length = g1_policy()->young_cset_region_length();
3424   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
3425   if (_surviving_young_words == NULL) {
3426     vm_exit_out_of_memory(sizeof(size_t) * array_length,
3427                           "Not enough space for young surv words summary.");
3428   }
3429   memset(_surviving_young_words, 0, array_length * sizeof(size_t));
3430 #ifdef ASSERT
3431   for (size_t i = 0;  i < array_length; ++i) {
3432     assert( _surviving_young_words[i] == 0, "memset above" );
3433   }
3434 #endif // !ASSERT
3435 }
3436 
3437 void
3438 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3439   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3440   size_t array_length = g1_policy()->young_cset_region_length();
3441   for (size_t i = 0; i < array_length; ++i)
3442     _surviving_young_words[i] += surv_young_words[i];
3443 }
3444 
3445 void
3446 G1CollectedHeap::cleanup_surviving_young_words() {
3447   guarantee( _surviving_young_words != NULL, "pre-condition" );
3448   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3449   _surviving_young_words = NULL;
3450 }
3451 
3452 #ifdef ASSERT
3453 class VerifyCSetClosure: public HeapRegionClosure {
3454 public:
3455   bool doHeapRegion(HeapRegion* hr) {
3456     // Here we check that the CSet region's RSet is ready for parallel
3457     // iteration. The fields that we'll verify are only manipulated
3458     // when the region is part of a CSet and is collected. Afterwards,
3459     // we reset these fields when we clear the region's RSet (when the
3460     // region is freed) so they are ready when the region is
3461     // re-allocated. The only exception to this is if there's an
3462     // evacuation failure and instead of freeing the region we leave
3463     // it in the heap. In that case, we reset these fields during
3464     // evacuation failure handling.
3465     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3466 
3467     // Here's a good place to add any other checks we'd like to
3468     // perform on CSet regions.
3469     return false;
3470   }
3471 };
3472 #endif // ASSERT
3473 
3474 #if TASKQUEUE_STATS
3475 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3476   st->print_raw_cr("GC Task Stats");
3477   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3478   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3479 }
3480 
3481 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3482   print_taskqueue_stats_hdr(st);
3483 
3484   TaskQueueStats totals;
3485   const int n = workers() != NULL ? workers()->total_workers() : 1;
3486   for (int i = 0; i < n; ++i) {
3487     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3488     totals += task_queue(i)->stats;
3489   }
3490   st->print_raw("tot "); totals.print(st); st->cr();
3491 
3492   DEBUG_ONLY(totals.verify());
3493 }
3494 
3495 void G1CollectedHeap::reset_taskqueue_stats() {
3496   const int n = workers() != NULL ? workers()->total_workers() : 1;
3497   for (int i = 0; i < n; ++i) {
3498     task_queue(i)->stats.reset();
3499   }
3500 }
3501 #endif // TASKQUEUE_STATS
3502 
3503 bool
3504 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3505   assert_at_safepoint(true /* should_be_vm_thread */);
3506   guarantee(!is_gc_active(), "collection is not reentrant");
3507 
3508   if (GC_locker::check_active_before_gc()) {
3509     return false;
3510   }
3511 
3512   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3513   ResourceMark rm;
3514 
3515   if (PrintHeapAtGC) {
3516     Universe::print_heap_before_gc();
3517   }
3518 
3519   HRSPhaseSetter x(HRSPhaseEvacuation);
3520   verify_region_sets_optional();
3521   verify_dirty_young_regions();
3522 
3523   {
3524     // This call will decide whether this pause is an initial-mark
3525     // pause. If it is, during_initial_mark_pause() will return true
3526     // for the duration of this pause.
3527     g1_policy()->decide_on_conc_mark_initiation();
3528 
3529     // We do not allow initial-mark to be piggy-backed on a mixed GC.
3530     assert(!g1_policy()->during_initial_mark_pause() ||
3531             g1_policy()->gcs_are_young(), "sanity");
3532 
3533     // We also do not allow mixed GCs during marking.
3534     assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3535 
3536     char verbose_str[128];
3537     sprintf(verbose_str, "GC pause ");
3538     if (g1_policy()->gcs_are_young()) {
3539       strcat(verbose_str, "(young)");
3540     } else {
3541       strcat(verbose_str, "(mixed)");
3542     }
3543     if (g1_policy()->during_initial_mark_pause()) {
3544       strcat(verbose_str, " (initial-mark)");
3545       // We are about to start a marking cycle, so we increment the
3546       // full collection counter.
3547       increment_total_full_collections();
3548     }
3549 
3550     // if PrintGCDetails is on, we'll print long statistics information
3551     // in the collector policy code, so let's not print this as the output
3552     // is messy if we do.
3553     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
3554     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
3555     TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
3556 
3557     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3558     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3559 
3560     // If the secondary_free_list is not empty, append it to the
3561     // free_list. No need to wait for the cleanup operation to finish;
3562     // the region allocation code will check the secondary_free_list
3563     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3564     // set, skip this step so that the region allocation code has to
3565     // get entries from the secondary_free_list.
3566     if (!G1StressConcRegionFreeing) {
3567       append_secondary_free_list_if_not_empty_with_lock();
3568     }
3569 
3570     assert(check_young_list_well_formed(),
3571       "young list should be well formed");
3572 
3573     // Don't dynamically change the number of GC threads this early.  A value of
3574     // 0 is used to indicate serial work.  When parallel work is done,
3575     // it will be set.
3576 
3577     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3578       IsGCActiveMark x;
3579 
3580       gc_prologue(false);
3581       increment_total_collections(false /* full gc */);
3582       increment_gc_time_stamp();
3583 
3584       if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
3585         HandleMark hm;  // Discard invalid handles created during verification
3586         gclog_or_tty->print(" VerifyBeforeGC:");
3587         prepare_for_verify();
3588         Universe::verify(/* allow dirty */ false,
3589                          /* silent      */ false,
3590                          /* option      */ VerifyOption_G1UsePrevMarking);
3591 
3592       }
3593 
3594       COMPILER2_PRESENT(DerivedPointerTable::clear());
3595 
3596       // Please see comment in g1CollectedHeap.hpp and
3597       // G1CollectedHeap::ref_processing_init() to see how
3598       // reference processing currently works in G1.
3599 
3600       // Enable discovery in the STW reference processor
3601       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3602                                             true /*verify_no_refs*/);
3603 
3604       {
3605         // We want to temporarily turn off discovery by the
3606         // CM ref processor, if necessary, and turn it back on
3607         // on again later if we do. Using a scoped
3608         // NoRefDiscovery object will do this.
3609         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3610 
3611         // Forget the current alloc region (we might even choose it to be part
3612         // of the collection set!).
3613         release_mutator_alloc_region();
3614 
3615         // We should call this after we retire the mutator alloc
3616         // region(s) so that all the ALLOC / RETIRE events are generated
3617         // before the start GC event.
3618         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3619 
3620         // The elapsed time induced by the start time below deliberately elides
3621         // the possible verification above.
3622         double start_time_sec = os::elapsedTime();
3623         size_t start_used_bytes = used();
3624 
3625 #if YOUNG_LIST_VERBOSE
3626         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3627         _young_list->print();
3628         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3629 #endif // YOUNG_LIST_VERBOSE
3630 
3631         g1_policy()->record_collection_pause_start(start_time_sec,
3632                                                    start_used_bytes);
3633 
3634 #if YOUNG_LIST_VERBOSE
3635         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3636         _young_list->print();
3637 #endif // YOUNG_LIST_VERBOSE
3638 
3639         if (g1_policy()->during_initial_mark_pause()) {
3640           concurrent_mark()->checkpointRootsInitialPre();
3641         }
3642         perm_gen()->save_marks();
3643 
3644         // We must do this before any possible evacuation that should propagate
3645         // marks.
3646         if (mark_in_progress()) {
3647           double start_time_sec = os::elapsedTime();
3648 
3649           _cm->drainAllSATBBuffers();
3650           double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
3651           g1_policy()->record_satb_drain_time(finish_mark_ms);
3652         }
3653         // Record the number of elements currently on the mark stack, so we
3654         // only iterate over these.  (Since evacuation may add to the mark
3655         // stack, doing more exposes race conditions.)  If no mark is in
3656         // progress, this will be zero.
3657         _cm->set_oops_do_bound();
3658 
3659         if (mark_in_progress()) {
3660           concurrent_mark()->newCSet();
3661         }
3662 
3663 #if YOUNG_LIST_VERBOSE
3664         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3665         _young_list->print();
3666         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3667 #endif // YOUNG_LIST_VERBOSE
3668 
3669         g1_policy()->choose_collection_set(target_pause_time_ms);
3670 
3671         if (_hr_printer.is_active()) {
3672           HeapRegion* hr = g1_policy()->collection_set();
3673           while (hr != NULL) {
3674             G1HRPrinter::RegionType type;
3675             if (!hr->is_young()) {
3676               type = G1HRPrinter::Old;
3677             } else if (hr->is_survivor()) {
3678               type = G1HRPrinter::Survivor;
3679             } else {
3680               type = G1HRPrinter::Eden;
3681             }
3682             _hr_printer.cset(hr);
3683             hr = hr->next_in_collection_set();
3684           }
3685         }
3686 
3687         // We have chosen the complete collection set. If marking is
3688         // active then, we clear the region fields of any of the
3689         // concurrent marking tasks whose region fields point into
3690         // the collection set as these values will become stale. This
3691         // will cause the owning marking threads to claim a new region
3692         // when marking restarts.
3693         if (mark_in_progress()) {
3694           concurrent_mark()->reset_active_task_region_fields_in_cset();
3695         }
3696 
3697 #ifdef ASSERT
3698         VerifyCSetClosure cl;
3699         collection_set_iterate(&cl);
3700 #endif // ASSERT
3701 
3702         setup_surviving_young_words();
3703 
3704         // Initialize the GC alloc regions.
3705         init_gc_alloc_regions();
3706 
3707         // Actually do the work...
3708         evacuate_collection_set();
3709 
3710         free_collection_set(g1_policy()->collection_set());
3711         g1_policy()->clear_collection_set();
3712 
3713         cleanup_surviving_young_words();
3714 
3715         // Start a new incremental collection set for the next pause.
3716         g1_policy()->start_incremental_cset_building();
3717 
3718         // Clear the _cset_fast_test bitmap in anticipation of adding
3719         // regions to the incremental collection set for the next
3720         // evacuation pause.
3721         clear_cset_fast_test();
3722 
3723         _young_list->reset_sampled_info();
3724 
3725         // Don't check the whole heap at this point as the
3726         // GC alloc regions from this pause have been tagged
3727         // as survivors and moved on to the survivor list.
3728         // Survivor regions will fail the !is_young() check.
3729         assert(check_young_list_empty(false /* check_heap */),
3730           "young list should be empty");
3731 
3732 #if YOUNG_LIST_VERBOSE
3733         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3734         _young_list->print();
3735 #endif // YOUNG_LIST_VERBOSE
3736 
3737         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3738                                             _young_list->first_survivor_region(),
3739                                             _young_list->last_survivor_region());
3740 
3741         _young_list->reset_auxilary_lists();
3742 
3743         if (evacuation_failed()) {
3744           _summary_bytes_used = recalculate_used();
3745         } else {
3746           // The "used" of the the collection set have already been subtracted
3747           // when they were freed.  Add in the bytes evacuated.
3748           _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
3749         }
3750 
3751         if (g1_policy()->during_initial_mark_pause()) {
3752           concurrent_mark()->checkpointRootsInitialPost();
3753           set_marking_started();
3754           // CAUTION: after the doConcurrentMark() call below,
3755           // the concurrent marking thread(s) could be running
3756           // concurrently with us. Make sure that anything after
3757           // this point does not assume that we are the only GC thread
3758           // running. Note: of course, the actual marking work will
3759           // not start until the safepoint itself is released in
3760           // ConcurrentGCThread::safepoint_desynchronize().
3761           doConcurrentMark();
3762         }
3763 
3764         allocate_dummy_regions();
3765 
3766 #if YOUNG_LIST_VERBOSE
3767         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3768         _young_list->print();
3769         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3770 #endif // YOUNG_LIST_VERBOSE
3771 
3772         init_mutator_alloc_region();
3773 
3774         {
3775           size_t expand_bytes = g1_policy()->expansion_amount();
3776           if (expand_bytes > 0) {
3777             size_t bytes_before = capacity();
3778             if (!expand(expand_bytes)) {
3779               // We failed to expand the heap so let's verify that
3780               // committed/uncommitted amount match the backing store
3781               assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3782               assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3783             }
3784           }
3785         }
3786 
3787         double end_time_sec = os::elapsedTime();
3788         double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
3789         g1_policy()->record_pause_time_ms(pause_time_ms);
3790         int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3791                                 workers()->active_workers() : 1);
3792         g1_policy()->record_collection_pause_end(active_workers);
3793 
3794         MemoryService::track_memory_usage();
3795 
3796         // In prepare_for_verify() below we'll need to scan the deferred
3797         // update buffers to bring the RSets up-to-date if
3798         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3799         // the update buffers we'll probably need to scan cards on the
3800         // regions we just allocated to (i.e., the GC alloc
3801         // regions). However, during the last GC we called
3802         // set_saved_mark() on all the GC alloc regions, so card
3803         // scanning might skip the [saved_mark_word()...top()] area of
3804         // those regions (i.e., the area we allocated objects into
3805         // during the last GC). But it shouldn't. Given that
3806         // saved_mark_word() is conditional on whether the GC time stamp
3807         // on the region is current or not, by incrementing the GC time
3808         // stamp here we invalidate all the GC time stamps on all the
3809         // regions and saved_mark_word() will simply return top() for
3810         // all the regions. This is a nicer way of ensuring this rather
3811         // than iterating over the regions and fixing them. In fact, the
3812         // GC time stamp increment here also ensures that
3813         // saved_mark_word() will return top() between pauses, i.e.,
3814         // during concurrent refinement. So we don't need the
3815         // is_gc_active() check to decided which top to use when
3816         // scanning cards (see CR 7039627).
3817         increment_gc_time_stamp();
3818 
3819         if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
3820           HandleMark hm;  // Discard invalid handles created during verification
3821           gclog_or_tty->print(" VerifyAfterGC:");
3822           prepare_for_verify();
3823           Universe::verify(/* allow dirty */ true,
3824                            /* silent      */ false,
3825                            /* option      */ VerifyOption_G1UsePrevMarking);
3826         }
3827 
3828         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3829         ref_processor_stw()->verify_no_references_recorded();
3830 
3831         // CM reference discovery will be re-enabled if necessary.
3832       }
3833 
3834       {
3835         size_t expand_bytes = g1_policy()->expansion_amount();
3836         if (expand_bytes > 0) {
3837           size_t bytes_before = capacity();
3838           // No need for an ergo verbose message here,
3839           // expansion_amount() does this when it returns a value > 0.
3840           if (!expand(expand_bytes)) {
3841             // We failed to expand the heap so let's verify that
3842             // committed/uncommitted amount match the backing store
3843             assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3844             assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3845           }
3846         }
3847       }
3848 
3849       // We should do this after we potentially expand the heap so
3850       // that all the COMMIT events are generated before the end GC
3851       // event, and after we retire the GC alloc regions so that all
3852       // RETIRE events are generated before the end GC event.
3853       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3854 
3855       // We have to do this after we decide whether to expand the heap or not.
3856       g1_policy()->print_heap_transition();
3857 
3858       if (mark_in_progress()) {
3859         concurrent_mark()->update_g1_committed();
3860       }
3861 
3862 #ifdef TRACESPINNING
3863       ParallelTaskTerminator::print_termination_counts();
3864 #endif
3865 
3866       gc_epilogue(false);
3867     }
3868 
3869     if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
3870       gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
3871       print_tracing_info();
3872       vm_exit(-1);
3873     }
3874   }
3875 
3876   _hrs.verify_optional();
3877   verify_region_sets_optional();
3878 
3879   TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
3880   TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3881 
3882   if (PrintHeapAtGC) {
3883     Universe::print_heap_after_gc();
3884   }
3885   g1mm()->update_sizes();
3886 
3887   if (G1SummarizeRSetStats &&
3888       (G1SummarizeRSetStatsPeriod > 0) &&
3889       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3890     g1_rem_set()->print_summary_info();
3891   }
3892 
3893   return true;
3894 }
3895 
3896 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
3897 {
3898   size_t gclab_word_size;
3899   switch (purpose) {
3900     case GCAllocForSurvived:
3901       gclab_word_size = YoungPLABSize;
3902       break;
3903     case GCAllocForTenured:
3904       gclab_word_size = OldPLABSize;
3905       break;
3906     default:
3907       assert(false, "unknown GCAllocPurpose");
3908       gclab_word_size = OldPLABSize;
3909       break;
3910   }
3911   return gclab_word_size;
3912 }
3913 
3914 void G1CollectedHeap::init_mutator_alloc_region() {
3915   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
3916   _mutator_alloc_region.init();
3917 }
3918 
3919 void G1CollectedHeap::release_mutator_alloc_region() {
3920   _mutator_alloc_region.release();
3921   assert(_mutator_alloc_region.get() == NULL, "post-condition");
3922 }
3923 
3924 void G1CollectedHeap::init_gc_alloc_regions() {
3925   assert_at_safepoint(true /* should_be_vm_thread */);
3926 
3927   _survivor_gc_alloc_region.init();
3928   _old_gc_alloc_region.init();
3929   HeapRegion* retained_region = _retained_old_gc_alloc_region;
3930   _retained_old_gc_alloc_region = NULL;
3931 
3932   // We will discard the current GC alloc region if:
3933   // a) it's in the collection set (it can happen!),
3934   // b) it's already full (no point in using it),
3935   // c) it's empty (this means that it was emptied during
3936   // a cleanup and it should be on the free list now), or
3937   // d) it's humongous (this means that it was emptied
3938   // during a cleanup and was added to the free list, but
3939   // has been subseqently used to allocate a humongous
3940   // object that may be less than the region size).
3941   if (retained_region != NULL &&
3942       !retained_region->in_collection_set() &&
3943       !(retained_region->top() == retained_region->end()) &&
3944       !retained_region->is_empty() &&
3945       !retained_region->isHumongous()) {
3946     retained_region->set_saved_mark();
3947     // The retained region was added to the old region set when it was
3948     // retired. We have to remove it now, since we don't allow regions
3949     // we allocate to in the region sets. We'll re-add it later, when
3950     // it's retired again.
3951     _old_set.remove(retained_region);
3952     _old_gc_alloc_region.set(retained_region);
3953     _hr_printer.reuse(retained_region);
3954   }
3955 }
3956 
3957 void G1CollectedHeap::release_gc_alloc_regions() {
3958   _survivor_gc_alloc_region.release();
3959   // If we have an old GC alloc region to release, we'll save it in
3960   // _retained_old_gc_alloc_region. If we don't
3961   // _retained_old_gc_alloc_region will become NULL. This is what we
3962   // want either way so no reason to check explicitly for either
3963   // condition.
3964   _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
3965 }
3966 
3967 void G1CollectedHeap::abandon_gc_alloc_regions() {
3968   assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
3969   assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
3970   _retained_old_gc_alloc_region = NULL;
3971 }
3972 
3973 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3974   _drain_in_progress = false;
3975   set_evac_failure_closure(cl);
3976   _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3977 }
3978 
3979 void G1CollectedHeap::finalize_for_evac_failure() {
3980   assert(_evac_failure_scan_stack != NULL &&
3981          _evac_failure_scan_stack->length() == 0,
3982          "Postcondition");
3983   assert(!_drain_in_progress, "Postcondition");
3984   delete _evac_failure_scan_stack;
3985   _evac_failure_scan_stack = NULL;
3986 }
3987 
3988 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3989 private:
3990   G1CollectedHeap* _g1;
3991   DirtyCardQueue *_dcq;
3992   CardTableModRefBS* _ct_bs;
3993 
3994 public:
3995   UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3996     _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3997 
3998   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3999   virtual void do_oop(      oop* p) { do_oop_work(p); }
4000   template <class T> void do_oop_work(T* p) {
4001     assert(_from->is_in_reserved(p), "paranoia");
4002     if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
4003         !_from->is_survivor()) {
4004       size_t card_index = _ct_bs->index_for(p);
4005       if (_ct_bs->mark_card_deferred(card_index)) {
4006         _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
4007       }
4008     }
4009   }
4010 };
4011 
4012 class RemoveSelfPointerClosure: public ObjectClosure {
4013 private:
4014   G1CollectedHeap* _g1;
4015   ConcurrentMark* _cm;
4016   HeapRegion* _hr;
4017   size_t _prev_marked_bytes;
4018   size_t _next_marked_bytes;
4019   OopsInHeapRegionClosure *_cl;
4020 public:
4021   RemoveSelfPointerClosure(G1CollectedHeap* g1, HeapRegion* hr,
4022                            OopsInHeapRegionClosure* cl) :
4023     _g1(g1), _hr(hr), _cm(_g1->concurrent_mark()),  _prev_marked_bytes(0),
4024     _next_marked_bytes(0), _cl(cl) {}
4025 
4026   size_t prev_marked_bytes() { return _prev_marked_bytes; }
4027   size_t next_marked_bytes() { return _next_marked_bytes; }
4028 
4029   // <original comment>
4030   // The original idea here was to coalesce evacuated and dead objects.
4031   // However that caused complications with the block offset table (BOT).
4032   // In particular if there were two TLABs, one of them partially refined.
4033   // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
4034   // The BOT entries of the unrefined part of TLAB_2 point to the start
4035   // of TLAB_2. If the last object of the TLAB_1 and the first object
4036   // of TLAB_2 are coalesced, then the cards of the unrefined part
4037   // would point into middle of the filler object.
4038   // The current approach is to not coalesce and leave the BOT contents intact.
4039   // </original comment>
4040   //
4041   // We now reset the BOT when we start the object iteration over the
4042   // region and refine its entries for every object we come across. So
4043   // the above comment is not really relevant and we should be able
4044   // to coalesce dead objects if we want to.
4045   void do_object(oop obj) {
4046     HeapWord* obj_addr = (HeapWord*) obj;
4047     assert(_hr->is_in(obj_addr), "sanity");
4048     size_t obj_size = obj->size();
4049     _hr->update_bot_for_object(obj_addr, obj_size);
4050     if (obj->is_forwarded() && obj->forwardee() == obj) {
4051       // The object failed to move.
4052       assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
4053       _cm->markPrev(obj);
4054       assert(_cm->isPrevMarked(obj), "Should be marked!");
4055       _prev_marked_bytes += (obj_size * HeapWordSize);
4056       if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
4057         _cm->markAndGrayObjectIfNecessary(obj);
4058       }
4059       obj->set_mark(markOopDesc::prototype());
4060       // While we were processing RSet buffers during the
4061       // collection, we actually didn't scan any cards on the
4062       // collection set, since we didn't want to update remebered
4063       // sets with entries that point into the collection set, given
4064       // that live objects fromthe collection set are about to move
4065       // and such entries will be stale very soon. This change also
4066       // dealt with a reliability issue which involved scanning a
4067       // card in the collection set and coming across an array that
4068       // was being chunked and looking malformed. The problem is
4069       // that, if evacuation fails, we might have remembered set
4070       // entries missing given that we skipped cards on the
4071       // collection set. So, we'll recreate such entries now.
4072       obj->oop_iterate(_cl);
4073       assert(_cm->isPrevMarked(obj), "Should be marked!");
4074     } else {
4075       // The object has been either evacuated or is dead. Fill it with a
4076       // dummy object.
4077       MemRegion mr((HeapWord*)obj, obj_size);
4078       CollectedHeap::fill_with_object(mr);
4079       _cm->clearRangeBothMaps(mr);
4080     }
4081   }
4082 };
4083 
4084 void G1CollectedHeap::remove_self_forwarding_pointers() {
4085   UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
4086   DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
4087   UpdateRSetDeferred deferred_update(_g1h, &dcq);
4088   OopsInHeapRegionClosure *cl;
4089   if (G1DeferredRSUpdate) {
4090     cl = &deferred_update;
4091   } else {
4092     cl = &immediate_update;
4093   }
4094   HeapRegion* cur = g1_policy()->collection_set();
4095   while (cur != NULL) {
4096     assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
4097     assert(!cur->isHumongous(), "sanity");
4098 
4099     if (cur->evacuation_failed()) {
4100       assert(cur->in_collection_set(), "bad CS");
4101       RemoveSelfPointerClosure rspc(_g1h, cur, cl);
4102 
4103       // In the common case we make sure that this is done when the
4104       // region is freed so that it is "ready-to-go" when it's
4105       // re-allocated. However, when evacuation failure happens, a
4106       // region will remain in the heap and might ultimately be added
4107       // to a CSet in the future. So we have to be careful here and
4108       // make sure the region's RSet is ready for parallel iteration
4109       // whenever this might be required in the future.
4110       cur->rem_set()->reset_for_par_iteration();
4111       cur->reset_bot();
4112       cl->set_region(cur);
4113       cur->object_iterate(&rspc);
4114 
4115       // A number of manipulations to make the TAMS be the current top,
4116       // and the marked bytes be the ones observed in the iteration.
4117       if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
4118         // The comments below are the postconditions achieved by the
4119         // calls.  Note especially the last such condition, which says that
4120         // the count of marked bytes has been properly restored.
4121         cur->note_start_of_marking(false);
4122         // _next_top_at_mark_start == top, _next_marked_bytes == 0
4123         cur->add_to_marked_bytes(rspc.prev_marked_bytes());
4124         // _next_marked_bytes == prev_marked_bytes.
4125         cur->note_end_of_marking();
4126         // _prev_top_at_mark_start == top(),
4127         // _prev_marked_bytes == prev_marked_bytes
4128       }
4129       // If there is no mark in progress, we modified the _next variables
4130       // above needlessly, but harmlessly.
4131       if (_g1h->mark_in_progress()) {
4132         cur->note_start_of_marking(false);
4133         // _next_top_at_mark_start == top, _next_marked_bytes == 0
4134         // _next_marked_bytes == next_marked_bytes.
4135       }
4136     }
4137     cur = cur->next_in_collection_set();
4138   }
4139   assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
4140 
4141   // Now restore saved marks, if any.
4142   if (_objs_with_preserved_marks != NULL) {
4143     assert(_preserved_marks_of_objs != NULL, "Both or none.");
4144     guarantee(_objs_with_preserved_marks->length() ==
4145               _preserved_marks_of_objs->length(), "Both or none.");
4146     for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
4147       oop obj   = _objs_with_preserved_marks->at(i);
4148       markOop m = _preserved_marks_of_objs->at(i);
4149       obj->set_mark(m);
4150     }
4151     // Delete the preserved marks growable arrays (allocated on the C heap).
4152     delete _objs_with_preserved_marks;
4153     delete _preserved_marks_of_objs;
4154     _objs_with_preserved_marks = NULL;
4155     _preserved_marks_of_objs = NULL;
4156   }
4157 }
4158 
4159 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4160   _evac_failure_scan_stack->push(obj);
4161 }
4162 
4163 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4164   assert(_evac_failure_scan_stack != NULL, "precondition");
4165 
4166   while (_evac_failure_scan_stack->length() > 0) {
4167      oop obj = _evac_failure_scan_stack->pop();
4168      _evac_failure_closure->set_region(heap_region_containing(obj));
4169      obj->oop_iterate_backwards(_evac_failure_closure);
4170   }
4171 }
4172 
4173 oop
4174 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
4175                                                oop old,
4176                                                bool should_mark_root) {
4177   assert(obj_in_cs(old),
4178          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4179                  (HeapWord*) old));
4180   markOop m = old->mark();
4181   oop forward_ptr = old->forward_to_atomic(old);
4182   if (forward_ptr == NULL) {
4183     // Forward-to-self succeeded.
4184 
4185     // should_mark_root will be true when this routine is called
4186     // from a root scanning closure during an initial mark pause.
4187     // In this case the thread that succeeds in self-forwarding the
4188     // object is also responsible for marking the object.
4189     if (should_mark_root) {
4190       assert(!oopDesc::is_null(old), "shouldn't be");
4191       _cm->grayRoot(old);
4192     }
4193 
4194     if (_evac_failure_closure != cl) {
4195       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4196       assert(!_drain_in_progress,
4197              "Should only be true while someone holds the lock.");
4198       // Set the global evac-failure closure to the current thread's.
4199       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4200       set_evac_failure_closure(cl);
4201       // Now do the common part.
4202       handle_evacuation_failure_common(old, m);
4203       // Reset to NULL.
4204       set_evac_failure_closure(NULL);
4205     } else {
4206       // The lock is already held, and this is recursive.
4207       assert(_drain_in_progress, "This should only be the recursive case.");
4208       handle_evacuation_failure_common(old, m);
4209     }
4210     return old;
4211   } else {
4212     // Forward-to-self failed. Either someone else managed to allocate
4213     // space for this object (old != forward_ptr) or they beat us in
4214     // self-forwarding it (old == forward_ptr).
4215     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4216            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4217                    "should not be in the CSet",
4218                    (HeapWord*) old, (HeapWord*) forward_ptr));
4219     return forward_ptr;
4220   }
4221 }
4222 
4223 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4224   set_evacuation_failed(true);
4225 
4226   preserve_mark_if_necessary(old, m);
4227 
4228   HeapRegion* r = heap_region_containing(old);
4229   if (!r->evacuation_failed()) {
4230     r->set_evacuation_failed(true);
4231     _hr_printer.evac_failure(r);
4232   }
4233 
4234   push_on_evac_failure_scan_stack(old);
4235 
4236   if (!_drain_in_progress) {
4237     // prevent recursion in copy_to_survivor_space()
4238     _drain_in_progress = true;
4239     drain_evac_failure_scan_stack();
4240     _drain_in_progress = false;
4241   }
4242 }
4243 
4244 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4245   assert(evacuation_failed(), "Oversaving!");
4246   // We want to call the "for_promotion_failure" version only in the
4247   // case of a promotion failure.
4248   if (m->must_be_preserved_for_promotion_failure(obj)) {
4249     if (_objs_with_preserved_marks == NULL) {
4250       assert(_preserved_marks_of_objs == NULL, "Both or none.");
4251       _objs_with_preserved_marks =
4252         new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
4253       _preserved_marks_of_objs =
4254         new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
4255     }
4256     _objs_with_preserved_marks->push(obj);
4257     _preserved_marks_of_objs->push(m);
4258   }
4259 }
4260 
4261 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4262                                                   size_t word_size) {
4263   if (purpose == GCAllocForSurvived) {
4264     HeapWord* result = survivor_attempt_allocation(word_size);
4265     if (result != NULL) {
4266       return result;
4267     } else {
4268       // Let's try to allocate in the old gen in case we can fit the
4269       // object there.
4270       return old_attempt_allocation(word_size);
4271     }
4272   } else {
4273     assert(purpose ==  GCAllocForTenured, "sanity");
4274     HeapWord* result = old_attempt_allocation(word_size);
4275     if (result != NULL) {
4276       return result;
4277     } else {
4278       // Let's try to allocate in the survivors in case we can fit the
4279       // object there.
4280       return survivor_attempt_allocation(word_size);
4281     }
4282   }
4283 
4284   ShouldNotReachHere();
4285   // Trying to keep some compilers happy.
4286   return NULL;
4287 }
4288 
4289 #ifndef PRODUCT
4290 bool GCLabBitMapClosure::do_bit(size_t offset) {
4291   HeapWord* addr = _bitmap->offsetToHeapWord(offset);
4292   guarantee(_cm->isMarked(oop(addr)), "it should be!");
4293   return true;
4294 }
4295 #endif // PRODUCT
4296 
4297 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4298   ParGCAllocBuffer(gclab_word_size),
4299   _should_mark_objects(false),
4300   _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
4301   _retired(false)
4302 {
4303   //_should_mark_objects is set to true when G1ParCopyHelper needs to
4304   // mark the forwarded location of an evacuated object.
4305   // We set _should_mark_objects to true if marking is active, i.e. when we
4306   // need to propagate a mark, or during an initial mark pause, i.e. when we
4307   // need to mark objects immediately reachable by the roots.
4308   if (G1CollectedHeap::heap()->mark_in_progress() ||
4309       G1CollectedHeap::heap()->g1_policy()->during_initial_mark_pause()) {
4310     _should_mark_objects = true;
4311   }
4312 }
4313 
4314 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
4315   : _g1h(g1h),
4316     _refs(g1h->task_queue(queue_num)),
4317     _dcq(&g1h->dirty_card_queue_set()),
4318     _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4319     _g1_rem(g1h->g1_rem_set()),
4320     _hash_seed(17), _queue_num(queue_num),
4321     _term_attempts(0),
4322     _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4323     _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4324     _age_table(false),
4325     _strong_roots_time(0), _term_time(0),
4326     _alloc_buffer_waste(0), _undo_waste(0)
4327 {
4328   // we allocate G1YoungSurvRateNumRegions plus one entries, since
4329   // we "sacrifice" entry 0 to keep track of surviving bytes for
4330   // non-young regions (where the age is -1)
4331   // We also add a few elements at the beginning and at the end in
4332   // an attempt to eliminate cache contention
4333   size_t real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4334   size_t array_length = PADDING_ELEM_NUM +
4335                         real_length +
4336                         PADDING_ELEM_NUM;
4337   _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
4338   if (_surviving_young_words_base == NULL)
4339     vm_exit_out_of_memory(array_length * sizeof(size_t),
4340                           "Not enough space for young surv histo.");
4341   _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4342   memset(_surviving_young_words, 0, real_length * sizeof(size_t));
4343 
4344   _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4345   _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;
4346 
4347   _start = os::elapsedTime();
4348 }
4349 
4350 void
4351 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4352 {
4353   st->print_raw_cr("GC Termination Stats");
4354   st->print_raw_cr("     elapsed  --strong roots-- -------termination-------"
4355                    " ------waste (KiB)------");
4356   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts"
4357                    "  total   alloc    undo");
4358   st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4359                    " ------- ------- -------");
4360 }
4361 
4362 void
4363 G1ParScanThreadState::print_termination_stats(int i,
4364                                               outputStream* const st) const
4365 {
4366   const double elapsed_ms = elapsed_time() * 1000.0;
4367   const double s_roots_ms = strong_roots_time() * 1000.0;
4368   const double term_ms    = term_time() * 1000.0;
4369   st->print_cr("%3d %9.2f %9.2f %6.2f "
4370                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4371                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4372                i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4373                term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4374                (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4375                alloc_buffer_waste() * HeapWordSize / K,
4376                undo_waste() * HeapWordSize / K);
4377 }
4378 
4379 #ifdef ASSERT
4380 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4381   assert(ref != NULL, "invariant");
4382   assert(UseCompressedOops, "sanity");
4383   assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4384   oop p = oopDesc::load_decode_heap_oop(ref);
4385   assert(_g1h->is_in_g1_reserved(p),
4386          err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4387   return true;
4388 }
4389 
4390 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4391   assert(ref != NULL, "invariant");
4392   if (has_partial_array_mask(ref)) {
4393     // Must be in the collection set--it's already been copied.
4394     oop p = clear_partial_array_mask(ref);
4395     assert(_g1h->obj_in_cs(p),
4396            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4397   } else {
4398     oop p = oopDesc::load_decode_heap_oop(ref);
4399     assert(_g1h->is_in_g1_reserved(p),
4400            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4401   }
4402   return true;
4403 }
4404 
4405 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4406   if (ref.is_narrow()) {
4407     return verify_ref((narrowOop*) ref);
4408   } else {
4409     return verify_ref((oop*) ref);
4410   }
4411 }
4412 #endif // ASSERT
4413 
4414 void G1ParScanThreadState::trim_queue() {
4415   assert(_evac_cl != NULL, "not set");
4416   assert(_evac_failure_cl != NULL, "not set");
4417   assert(_partial_scan_cl != NULL, "not set");
4418 
4419   StarTask ref;
4420   do {
4421     // Drain the overflow stack first, so other threads can steal.
4422     while (refs()->pop_overflow(ref)) {
4423       deal_with_reference(ref);
4424     }
4425 
4426     while (refs()->pop_local(ref)) {
4427       deal_with_reference(ref);
4428     }
4429   } while (!refs()->is_empty());
4430 }
4431 
4432 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
4433   _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4434   _par_scan_state(par_scan_state),
4435   _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4436   _mark_in_progress(_g1->mark_in_progress()) { }
4437 
4438 template <class T> void G1ParCopyHelper::mark_object(T* p) {
4439   // This is called from do_oop_work for objects that are not
4440   // in the collection set. Objects in the collection set
4441   // are marked after they have been evacuated.
4442 
4443   T heap_oop = oopDesc::load_heap_oop(p);
4444   if (!oopDesc::is_null(heap_oop)) {
4445     oop obj = oopDesc::decode_heap_oop(heap_oop);
4446     HeapWord* addr = (HeapWord*)obj;
4447     if (_g1->is_in_g1_reserved(addr)) {
4448       _cm->grayRoot(oop(addr));
4449     }
4450   }
4451 }
4452 
4453 oop G1ParCopyHelper::copy_to_survivor_space(oop old, bool should_mark_root,
4454                                                      bool should_mark_copy) {
4455   size_t    word_sz = old->size();
4456   HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4457   // +1 to make the -1 indexes valid...
4458   int       young_index = from_region->young_index_in_cset()+1;
4459   assert( (from_region->is_young() && young_index > 0) ||
4460           (!from_region->is_young() && young_index == 0), "invariant" );
4461   G1CollectorPolicy* g1p = _g1->g1_policy();
4462   markOop m = old->mark();
4463   int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4464                                            : m->age();
4465   GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4466                                                              word_sz);
4467   HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4468   oop       obj     = oop(obj_ptr);
4469 
4470   if (obj_ptr == NULL) {
4471     // This will either forward-to-self, or detect that someone else has
4472     // installed a forwarding pointer.
4473     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4474     return _g1->handle_evacuation_failure_par(cl, old, should_mark_root);
4475   }
4476 
4477   // We're going to allocate linearly, so might as well prefetch ahead.
4478   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4479 
4480   oop forward_ptr = old->forward_to_atomic(obj);
4481   if (forward_ptr == NULL) {
4482     Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4483     if (g1p->track_object_age(alloc_purpose)) {
4484       // We could simply do obj->incr_age(). However, this causes a
4485       // performance issue. obj->incr_age() will first check whether
4486       // the object has a displaced mark by checking its mark word;
4487       // getting the mark word from the new location of the object
4488       // stalls. So, given that we already have the mark word and we
4489       // are about to install it anyway, it's better to increase the
4490       // age on the mark word, when the object does not have a
4491       // displaced mark word. We're not expecting many objects to have
4492       // a displaced marked word, so that case is not optimized
4493       // further (it could be...) and we simply call obj->incr_age().
4494 
4495       if (m->has_displaced_mark_helper()) {
4496         // in this case, we have to install the mark word first,
4497         // otherwise obj looks to be forwarded (the old mark word,
4498         // which contains the forward pointer, was copied)
4499         obj->set_mark(m);
4500         obj->incr_age();
4501       } else {
4502         m = m->incr_age();
4503         obj->set_mark(m);
4504       }
4505       _par_scan_state->age_table()->add(obj, word_sz);
4506     } else {
4507       obj->set_mark(m);
4508     }
4509 
4510     // Mark the evacuated object or propagate "next" mark bit
4511     if (should_mark_copy) {
4512       if (!use_local_bitmaps ||
4513           !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
4514         // if we couldn't mark it on the local bitmap (this happens when
4515         // the object was not allocated in the GCLab), we have to bite
4516         // the bullet and do the standard parallel mark
4517         _cm->markAndGrayObjectIfNecessary(obj);
4518       }
4519 
4520       if (_g1->isMarkedNext(old)) {
4521         // Unmark the object's old location so that marking
4522         // doesn't think the old object is alive.
4523         _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4524       }
4525     }
4526 
4527     size_t* surv_young_words = _par_scan_state->surviving_young_words();
4528     surv_young_words[young_index] += word_sz;
4529 
4530     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4531       arrayOop(old)->set_length(0);
4532       oop* old_p = set_partial_array_mask(old);
4533       _par_scan_state->push_on_queue(old_p);
4534     } else {
4535       // No point in using the slower heap_region_containing() method,
4536       // given that we know obj is in the heap.
4537       _scanner->set_region(_g1->heap_region_containing_raw(obj));
4538       obj->oop_iterate_backwards(_scanner);
4539     }
4540   } else {
4541     _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4542     obj = forward_ptr;
4543   }
4544   return obj;
4545 }
4546 
4547 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4548 template <class T>
4549 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4550 ::do_oop_work(T* p) {
4551   oop obj = oopDesc::load_decode_heap_oop(p);
4552   assert(barrier != G1BarrierRS || obj != NULL,
4553          "Precondition: G1BarrierRS implies obj is nonNull");
4554 
4555   // Marking:
4556   // If the object is in the collection set, then the thread
4557   // that copies the object should mark, or propagate the
4558   // mark to, the evacuated object.
4559   // If the object is not in the collection set then we
4560   // should call the mark_object() method depending on the
4561   // value of the template parameter do_mark_object (which will
4562   // be true for root scanning closures during an initial mark
4563   // pause).
4564   // The mark_object() method first checks whether the object
4565   // is marked and, if not, attempts to mark the object.
4566 
4567   // here the null check is implicit in the cset_fast_test() test
4568   if (_g1->in_cset_fast_test(obj)) {
4569     if (obj->is_forwarded()) {
4570       oopDesc::encode_store_heap_oop(p, obj->forwardee());
4571       // If we are a root scanning closure during an initial
4572       // mark pause (i.e. do_mark_object will be true) then
4573       // we also need to handle marking of roots in the
4574       // event of an evacuation failure. In the event of an
4575       // evacuation failure, the object is forwarded to itself
4576       // and not copied. For root-scanning closures, the
4577       // object would be marked after a successful self-forward
4578       // but an object could be pointed to by both a root and non
4579       // root location and be self-forwarded by a non-root-scanning
4580       // closure. Therefore we also have to attempt to mark the
4581       // self-forwarded root object here.
4582       if (do_mark_object && obj->forwardee() == obj) {
4583         mark_object(p);
4584       }
4585     } else {
4586       // During an initial mark pause, objects that are pointed to
4587       // by the roots need to be marked - even in the event of an
4588       // evacuation failure. We pass the template parameter
4589       // do_mark_object (which is true for root scanning closures
4590       // during an initial mark pause) to copy_to_survivor_space
4591       // which will pass it on to the evacuation failure handling
4592       // code. The thread that successfully self-forwards a root
4593       // object to itself is responsible for marking the object.
4594       bool should_mark_root = do_mark_object;
4595 
4596       // We need to mark the copied object if we're a root scanning
4597       // closure during an initial mark pause (i.e. do_mark_object
4598       // will be true), or the object is already marked and we need
4599       // to propagate the mark to the evacuated copy.
4600       bool should_mark_copy = do_mark_object ||
4601                               _during_initial_mark ||
4602                               (_mark_in_progress && !_g1->is_obj_ill(obj));
4603 
4604       oop copy_oop = copy_to_survivor_space(obj, should_mark_root,
4605                                                  should_mark_copy);
4606       oopDesc::encode_store_heap_oop(p, copy_oop);
4607     }
4608     // When scanning the RS, we only care about objs in CS.
4609     if (barrier == G1BarrierRS) {
4610       _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4611     }
4612   } else {
4613     // The object is not in collection set. If we're a root scanning
4614     // closure during an initial mark pause (i.e. do_mark_object will
4615     // be true) then attempt to mark the object.
4616     if (do_mark_object) {
4617       mark_object(p);
4618     }
4619   }
4620 
4621   if (barrier == G1BarrierEvac && obj != NULL) {
4622     _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4623   }
4624 
4625   if (do_gen_barrier && obj != NULL) {
4626     par_do_barrier(p);
4627   }
4628 }
4629 
4630 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4631 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4632 
4633 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4634   assert(has_partial_array_mask(p), "invariant");
4635   oop old = clear_partial_array_mask(p);
4636   assert(old->is_objArray(), "must be obj array");
4637   assert(old->is_forwarded(), "must be forwarded");
4638   assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4639 
4640   objArrayOop obj = objArrayOop(old->forwardee());
4641   assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4642   // Process ParGCArrayScanChunk elements now
4643   // and push the remainder back onto queue
4644   int start     = arrayOop(old)->length();
4645   int end       = obj->length();
4646   int remainder = end - start;
4647   assert(start <= end, "just checking");
4648   if (remainder > 2 * ParGCArrayScanChunk) {
4649     // Test above combines last partial chunk with a full chunk
4650     end = start + ParGCArrayScanChunk;
4651     arrayOop(old)->set_length(end);
4652     // Push remainder.
4653     oop* old_p = set_partial_array_mask(old);
4654     assert(arrayOop(old)->length() < obj->length(), "Empty push?");
4655     _par_scan_state->push_on_queue(old_p);
4656   } else {
4657     // Restore length so that the heap remains parsable in
4658     // case of evacuation failure.
4659     arrayOop(old)->set_length(end);
4660   }
4661   _scanner.set_region(_g1->heap_region_containing_raw(obj));
4662   // process our set of indices (include header in first chunk)
4663   obj->oop_iterate_range(&_scanner, start, end);
4664 }
4665 
4666 class G1ParEvacuateFollowersClosure : public VoidClosure {
4667 protected:
4668   G1CollectedHeap*              _g1h;
4669   G1ParScanThreadState*         _par_scan_state;
4670   RefToScanQueueSet*            _queues;
4671   ParallelTaskTerminator*       _terminator;
4672 
4673   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4674   RefToScanQueueSet*      queues()         { return _queues; }
4675   ParallelTaskTerminator* terminator()     { return _terminator; }
4676 
4677 public:
4678   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4679                                 G1ParScanThreadState* par_scan_state,
4680                                 RefToScanQueueSet* queues,
4681                                 ParallelTaskTerminator* terminator)
4682     : _g1h(g1h), _par_scan_state(par_scan_state),
4683       _queues(queues), _terminator(terminator) {}
4684 
4685   void do_void();
4686 
4687 private:
4688   inline bool offer_termination();
4689 };
4690 
4691 bool G1ParEvacuateFollowersClosure::offer_termination() {
4692   G1ParScanThreadState* const pss = par_scan_state();
4693   pss->start_term_time();
4694   const bool res = terminator()->offer_termination();
4695   pss->end_term_time();
4696   return res;
4697 }
4698 
4699 void G1ParEvacuateFollowersClosure::do_void() {
4700   StarTask stolen_task;
4701   G1ParScanThreadState* const pss = par_scan_state();
4702   pss->trim_queue();
4703 
4704   do {
4705     while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4706       assert(pss->verify_task(stolen_task), "sanity");
4707       if (stolen_task.is_narrow()) {
4708         pss->deal_with_reference((narrowOop*) stolen_task);
4709       } else {
4710         pss->deal_with_reference((oop*) stolen_task);
4711       }
4712 
4713       // We've just processed a reference and we might have made
4714       // available new entries on the queues. So we have to make sure
4715       // we drain the queues as necessary.
4716       pss->trim_queue();
4717     }
4718   } while (!offer_termination());
4719 
4720   pss->retire_alloc_buffers();
4721 }
4722 
4723 class G1ParTask : public AbstractGangTask {
4724 protected:
4725   G1CollectedHeap*       _g1h;
4726   RefToScanQueueSet      *_queues;
4727   ParallelTaskTerminator _terminator;
4728   int _n_workers;
4729 
4730   Mutex _stats_lock;
4731   Mutex* stats_lock() { return &_stats_lock; }
4732 
4733   size_t getNCards() {
4734     return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4735       / G1BlockOffsetSharedArray::N_bytes;
4736   }
4737 
4738 public:
4739   G1ParTask(G1CollectedHeap* g1h,
4740             RefToScanQueueSet *task_queues)
4741     : AbstractGangTask("G1 collection"),
4742       _g1h(g1h),
4743       _queues(task_queues),
4744       _terminator(0, _queues),
4745       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4746   {}
4747 
4748   RefToScanQueueSet* queues() { return _queues; }
4749 
4750   RefToScanQueue *work_queue(int i) {
4751     return queues()->queue(i);
4752   }
4753 
4754   ParallelTaskTerminator* terminator() { return &_terminator; }
4755 
4756   virtual void set_for_termination(int active_workers) {
4757     // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4758     // in the young space (_par_seq_tasks) in the G1 heap
4759     // for SequentialSubTasksDone.
4760     // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4761     // both of which need setting by set_n_termination().
4762     _g1h->SharedHeap::set_n_termination(active_workers);
4763     _g1h->set_n_termination(active_workers);
4764     terminator()->reset_for_reuse(active_workers);
4765     _n_workers = active_workers;
4766   }
4767 
4768   void work(int i) {
4769     if (i >= _n_workers) return;  // no work needed this round
4770 
4771     double start_time_ms = os::elapsedTime() * 1000.0;
4772     _g1h->g1_policy()->record_gc_worker_start_time(i, start_time_ms);
4773 
4774     ResourceMark rm;
4775     HandleMark   hm;
4776 
4777     ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4778 
4779     G1ParScanThreadState            pss(_g1h, i);
4780     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, rp);
4781     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4782     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, rp);
4783 
4784     pss.set_evac_closure(&scan_evac_cl);
4785     pss.set_evac_failure_closure(&evac_failure_cl);
4786     pss.set_partial_scan_closure(&partial_scan_cl);
4787 
4788     G1ParScanExtRootClosure        only_scan_root_cl(_g1h, &pss, rp);
4789     G1ParScanPermClosure           only_scan_perm_cl(_g1h, &pss, rp);
4790 
4791     G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4792     G1ParScanAndMarkPermClosure    scan_mark_perm_cl(_g1h, &pss, rp);
4793 
4794     OopClosure*                    scan_root_cl = &only_scan_root_cl;
4795     OopsInHeapRegionClosure*       scan_perm_cl = &only_scan_perm_cl;
4796 
4797     if (_g1h->g1_policy()->during_initial_mark_pause()) {
4798       // We also need to mark copied objects.
4799       scan_root_cl = &scan_mark_root_cl;
4800       scan_perm_cl = &scan_mark_perm_cl;
4801     }
4802 
4803     G1ParPushHeapRSClosure          push_heap_rs_cl(_g1h, &pss);
4804 
4805     pss.start_strong_roots();
4806     _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4807                                   SharedHeap::SO_AllClasses,
4808                                   scan_root_cl,
4809                                   &push_heap_rs_cl,
4810                                   scan_perm_cl,
4811                                   i);
4812     pss.end_strong_roots();
4813 
4814     {
4815       double start = os::elapsedTime();
4816       G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4817       evac.do_void();
4818       double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4819       double term_ms = pss.term_time()*1000.0;
4820       _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4821       _g1h->g1_policy()->record_termination(i, term_ms, pss.term_attempts());
4822     }
4823     _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4824     _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4825 
4826     // Clean up any par-expanded rem sets.
4827     HeapRegionRemSet::par_cleanup();
4828 
4829     if (ParallelGCVerbose) {
4830       MutexLocker x(stats_lock());
4831       pss.print_termination_stats(i);
4832     }
4833 
4834     assert(pss.refs()->is_empty(), "should be empty");
4835     double end_time_ms = os::elapsedTime() * 1000.0;
4836     _g1h->g1_policy()->record_gc_worker_end_time(i, end_time_ms);
4837   }
4838 };
4839 
4840 // *** Common G1 Evacuation Stuff
4841 
4842 // This method is run in a GC worker.
4843 
4844 void
4845 G1CollectedHeap::
4846 g1_process_strong_roots(bool collecting_perm_gen,
4847                         SharedHeap::ScanningOption so,
4848                         OopClosure* scan_non_heap_roots,
4849                         OopsInHeapRegionClosure* scan_rs,
4850                         OopsInGenClosure* scan_perm,
4851                         int worker_i) {
4852 
4853   // First scan the strong roots, including the perm gen.
4854   double ext_roots_start = os::elapsedTime();
4855   double closure_app_time_sec = 0.0;
4856 
4857   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4858   BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4859   buf_scan_perm.set_generation(perm_gen());
4860 
4861   // Walk the code cache w/o buffering, because StarTask cannot handle
4862   // unaligned oop locations.
4863   CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
4864 
4865   process_strong_roots(false, // no scoping; this is parallel code
4866                        collecting_perm_gen, so,
4867                        &buf_scan_non_heap_roots,
4868                        &eager_scan_code_roots,
4869                        &buf_scan_perm);
4870 
4871   // Now the CM ref_processor roots.
4872   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4873     // We need to treat the discovered reference lists of the
4874     // concurrent mark ref processor as roots and keep entries
4875     // (which are added by the marking threads) on them live
4876     // until they can be processed at the end of marking.
4877     ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4878   }
4879 
4880   // Finish up any enqueued closure apps (attributed as object copy time).
4881   buf_scan_non_heap_roots.done();
4882   buf_scan_perm.done();
4883 
4884   double ext_roots_end = os::elapsedTime();
4885 
4886   g1_policy()->reset_obj_copy_time(worker_i);
4887   double obj_copy_time_sec = buf_scan_perm.closure_app_seconds() +
4888                                 buf_scan_non_heap_roots.closure_app_seconds();
4889   g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4890 
4891   double ext_root_time_ms =
4892     ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4893 
4894   g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4895 
4896   // Scan strong roots in mark stack.
4897   if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4898     concurrent_mark()->oops_do(scan_non_heap_roots);
4899   }
4900   double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4901   g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4902 
4903   // Now scan the complement of the collection set.
4904   if (scan_rs != NULL) {
4905     g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4906   }
4907 
4908   _process_strong_tasks->all_tasks_completed();
4909 }
4910 
4911 void
4912 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4913                                        OopClosure* non_root_closure) {
4914   CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4915   SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
4916 }
4917 
4918 // Weak Reference Processing support
4919 
4920 // An always "is_alive" closure that is used to preserve referents.
4921 // If the object is non-null then it's alive.  Used in the preservation
4922 // of referent objects that are pointed to by reference objects
4923 // discovered by the CM ref processor.
4924 class G1AlwaysAliveClosure: public BoolObjectClosure {
4925   G1CollectedHeap* _g1;
4926 public:
4927   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4928   void do_object(oop p) { assert(false, "Do not call."); }
4929   bool do_object_b(oop p) {
4930     if (p != NULL) {
4931       return true;
4932     }
4933     return false;
4934   }
4935 };
4936 
4937 bool G1STWIsAliveClosure::do_object_b(oop p) {
4938   // An object is reachable if it is outside the collection set,
4939   // or is inside and copied.
4940   return !_g1->obj_in_cs(p) || p->is_forwarded();
4941 }
4942 
4943 // Non Copying Keep Alive closure
4944 class G1KeepAliveClosure: public OopClosure {
4945   G1CollectedHeap* _g1;
4946 public:
4947   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4948   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4949   void do_oop(      oop* p) {
4950     oop obj = *p;
4951 
4952     if (_g1->obj_in_cs(obj)) {
4953       assert( obj->is_forwarded(), "invariant" );
4954       *p = obj->forwardee();
4955     }
4956   }
4957 };
4958 
4959 // Copying Keep Alive closure - can be called from both
4960 // serial and parallel code as long as different worker
4961 // threads utilize different G1ParScanThreadState instances
4962 // and different queues.
4963 
4964 class G1CopyingKeepAliveClosure: public OopClosure {
4965   G1CollectedHeap*         _g1h;
4966   OopClosure*              _copy_non_heap_obj_cl;
4967   OopsInHeapRegionClosure* _copy_perm_obj_cl;
4968   G1ParScanThreadState*    _par_scan_state;
4969 
4970 public:
4971   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4972                             OopClosure* non_heap_obj_cl,
4973                             OopsInHeapRegionClosure* perm_obj_cl,
4974                             G1ParScanThreadState* pss):
4975     _g1h(g1h),
4976     _copy_non_heap_obj_cl(non_heap_obj_cl),
4977     _copy_perm_obj_cl(perm_obj_cl),
4978     _par_scan_state(pss)
4979   {}
4980 
4981   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4982   virtual void do_oop(      oop* p) { do_oop_work(p); }
4983 
4984   template <class T> void do_oop_work(T* p) {
4985     oop obj = oopDesc::load_decode_heap_oop(p);
4986 
4987     if (_g1h->obj_in_cs(obj)) {
4988       // If the referent object has been forwarded (either copied
4989       // to a new location or to itself in the event of an
4990       // evacuation failure) then we need to update the reference
4991       // field and, if both reference and referent are in the G1
4992       // heap, update the RSet for the referent.
4993       //
4994       // If the referent has not been forwarded then we have to keep
4995       // it alive by policy. Therefore we have copy the referent.
4996       //
4997       // If the reference field is in the G1 heap then we can push
4998       // on the PSS queue. When the queue is drained (after each
4999       // phase of reference processing) the object and it's followers
5000       // will be copied, the reference field set to point to the
5001       // new location, and the RSet updated. Otherwise we need to
5002       // use the the non-heap or perm closures directly to copy
5003       // the refernt object and update the pointer, while avoiding
5004       // updating the RSet.
5005 
5006       if (_g1h->is_in_g1_reserved(p)) {
5007         _par_scan_state->push_on_queue(p);
5008       } else {
5009         // The reference field is not in the G1 heap.
5010         if (_g1h->perm_gen()->is_in(p)) {
5011           _copy_perm_obj_cl->do_oop(p);
5012         } else {
5013           _copy_non_heap_obj_cl->do_oop(p);
5014         }
5015       }
5016     }
5017   }
5018 };
5019 
5020 // Serial drain queue closure. Called as the 'complete_gc'
5021 // closure for each discovered list in some of the
5022 // reference processing phases.
5023 
5024 class G1STWDrainQueueClosure: public VoidClosure {
5025 protected:
5026   G1CollectedHeap* _g1h;
5027   G1ParScanThreadState* _par_scan_state;
5028 
5029   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5030 
5031 public:
5032   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5033     _g1h(g1h),
5034     _par_scan_state(pss)
5035   { }
5036 
5037   void do_void() {
5038     G1ParScanThreadState* const pss = par_scan_state();
5039     pss->trim_queue();
5040   }
5041 };
5042 
5043 // Parallel Reference Processing closures
5044 
5045 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5046 // processing during G1 evacuation pauses.
5047 
5048 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5049 private:
5050   G1CollectedHeap*   _g1h;
5051   RefToScanQueueSet* _queues;
5052   FlexibleWorkGang*  _workers;
5053   int                _active_workers;
5054 
5055 public:
5056   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5057                         FlexibleWorkGang* workers,
5058                         RefToScanQueueSet *task_queues,
5059                         int n_workers) :
5060     _g1h(g1h),
5061     _queues(task_queues),
5062     _workers(workers),
5063     _active_workers(n_workers)
5064   {
5065     assert(n_workers > 0, "shouldn't call this otherwise");
5066   }
5067 
5068   // Executes the given task using concurrent marking worker threads.
5069   virtual void execute(ProcessTask& task);
5070   virtual void execute(EnqueueTask& task);
5071 };
5072 
5073 // Gang task for possibly parallel reference processing
5074 
5075 class G1STWRefProcTaskProxy: public AbstractGangTask {
5076   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5077   ProcessTask&     _proc_task;
5078   G1CollectedHeap* _g1h;
5079   RefToScanQueueSet *_task_queues;
5080   ParallelTaskTerminator* _terminator;
5081 
5082 public:
5083   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5084                      G1CollectedHeap* g1h,
5085                      RefToScanQueueSet *task_queues,
5086                      ParallelTaskTerminator* terminator) :
5087     AbstractGangTask("Process reference objects in parallel"),
5088     _proc_task(proc_task),
5089     _g1h(g1h),
5090     _task_queues(task_queues),
5091     _terminator(terminator)
5092   {}
5093 
5094   virtual void work(int i) {
5095     // The reference processing task executed by a single worker.
5096     ResourceMark rm;
5097     HandleMark   hm;
5098 
5099     G1STWIsAliveClosure is_alive(_g1h);
5100 
5101     G1ParScanThreadState pss(_g1h, i);
5102 
5103     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5104     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5105     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5106 
5107     pss.set_evac_closure(&scan_evac_cl);
5108     pss.set_evac_failure_closure(&evac_failure_cl);
5109     pss.set_partial_scan_closure(&partial_scan_cl);
5110 
5111     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5112     G1ParScanPermClosure           only_copy_perm_cl(_g1h, &pss, NULL);
5113 
5114     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5115     G1ParScanAndMarkPermClosure    copy_mark_perm_cl(_g1h, &pss, NULL);
5116 
5117     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5118     OopsInHeapRegionClosure*       copy_perm_cl = &only_copy_perm_cl;
5119 
5120     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5121       // We also need to mark copied objects.
5122       copy_non_heap_cl = &copy_mark_non_heap_cl;
5123       copy_perm_cl = &copy_mark_perm_cl;
5124     }
5125 
5126     // Keep alive closure.
5127     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5128 
5129     // Complete GC closure
5130     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5131 
5132     // Call the reference processing task's work routine.
5133     _proc_task.work(i, is_alive, keep_alive, drain_queue);
5134 
5135     // Note we cannot assert that the refs array is empty here as not all
5136     // of the processing tasks (specifically phase2 - pp2_work) execute
5137     // the complete_gc closure (which ordinarily would drain the queue) so
5138     // the queue may not be empty.
5139   }
5140 };
5141 
5142 // Driver routine for parallel reference processing.
5143 // Creates an instance of the ref processing gang
5144 // task and has the worker threads execute it.
5145 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5146   assert(_workers != NULL, "Need parallel worker threads.");
5147 
5148   ParallelTaskTerminator terminator(_active_workers, _queues);
5149   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5150 
5151   _g1h->set_par_threads(_active_workers);
5152   _workers->run_task(&proc_task_proxy);
5153   _g1h->set_par_threads(0);
5154 }
5155 
5156 // Gang task for parallel reference enqueueing.
5157 
5158 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5159   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5160   EnqueueTask& _enq_task;
5161 
5162 public:
5163   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5164     AbstractGangTask("Enqueue reference objects in parallel"),
5165     _enq_task(enq_task)
5166   { }
5167 
5168   virtual void work(int i) {
5169     _enq_task.work(i);
5170   }
5171 };
5172 
5173 // Driver routine for parallel reference enqueing.
5174 // Creates an instance of the ref enqueueing gang
5175 // task and has the worker threads execute it.
5176 
5177 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5178   assert(_workers != NULL, "Need parallel worker threads.");
5179 
5180   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5181 
5182   _g1h->set_par_threads(_active_workers);
5183   _workers->run_task(&enq_task_proxy);
5184   _g1h->set_par_threads(0);
5185 }
5186 
5187 // End of weak reference support closures
5188 
5189 // Abstract task used to preserve (i.e. copy) any referent objects
5190 // that are in the collection set and are pointed to by reference
5191 // objects discovered by the CM ref processor.
5192 
5193 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5194 protected:
5195   G1CollectedHeap* _g1h;
5196   RefToScanQueueSet      *_queues;
5197   ParallelTaskTerminator _terminator;
5198   int _n_workers;
5199 
5200 public:
5201   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5202     AbstractGangTask("ParPreserveCMReferents"),
5203     _g1h(g1h),
5204     _queues(task_queues),
5205     _terminator(workers, _queues),
5206     _n_workers(workers)
5207   { }
5208 
5209   void work(int i) {
5210     ResourceMark rm;
5211     HandleMark   hm;
5212 
5213     G1ParScanThreadState            pss(_g1h, i);
5214     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
5215     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5216     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
5217 
5218     pss.set_evac_closure(&scan_evac_cl);
5219     pss.set_evac_failure_closure(&evac_failure_cl);
5220     pss.set_partial_scan_closure(&partial_scan_cl);
5221 
5222     assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5223 
5224 
5225     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5226     G1ParScanPermClosure           only_copy_perm_cl(_g1h, &pss, NULL);
5227 
5228     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5229     G1ParScanAndMarkPermClosure    copy_mark_perm_cl(_g1h, &pss, NULL);
5230 
5231     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5232     OopsInHeapRegionClosure*       copy_perm_cl = &only_copy_perm_cl;
5233 
5234     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5235       // We also need to mark copied objects.
5236       copy_non_heap_cl = &copy_mark_non_heap_cl;
5237       copy_perm_cl = &copy_mark_perm_cl;
5238     }
5239 
5240     // Is alive closure
5241     G1AlwaysAliveClosure always_alive(_g1h);
5242 
5243     // Copying keep alive closure. Applied to referent objects that need
5244     // to be copied.
5245     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5246 
5247     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5248 
5249     int limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5250     int stride = MIN2(MAX2(_n_workers, 1), limit);
5251 
5252     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5253     // So this must be true - but assert just in case someone decides to
5254     // change the worker ids.
5255     assert(0 <= i && i < limit, "sanity");
5256     assert(!rp->discovery_is_atomic(), "check this code");
5257 
5258     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5259     for (int idx = i; idx < limit; idx += stride) {
5260       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5261 
5262       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5263       while (iter.has_next()) {
5264         // Since discovery is not atomic for the CM ref processor, we
5265         // can see some null referent objects.
5266         iter.load_ptrs(DEBUG_ONLY(true));
5267         oop ref = iter.obj();
5268 
5269         // This will filter nulls.
5270         if (iter.is_referent_alive()) {
5271           iter.make_referent_alive();
5272         }
5273         iter.move_to_next();
5274       }
5275     }
5276 
5277     // Drain the queue - which may cause stealing
5278     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5279     drain_queue.do_void();
5280     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5281     assert(pss.refs()->is_empty(), "should be");
5282   }
5283 };
5284 
5285 // Weak Reference processing during an evacuation pause (part 1).
5286 void G1CollectedHeap::process_discovered_references() {
5287   double ref_proc_start = os::elapsedTime();
5288 
5289   ReferenceProcessor* rp = _ref_processor_stw;
5290   assert(rp->discovery_enabled(), "should have been enabled");
5291 
5292   // Any reference objects, in the collection set, that were 'discovered'
5293   // by the CM ref processor should have already been copied (either by
5294   // applying the external root copy closure to the discovered lists, or
5295   // by following an RSet entry).
5296   //
5297   // But some of the referents, that are in the collection set, that these
5298   // reference objects point to may not have been copied: the STW ref
5299   // processor would have seen that the reference object had already
5300   // been 'discovered' and would have skipped discovering the reference,
5301   // but would not have treated the reference object as a regular oop.
5302   // As a reult the copy closure would not have been applied to the
5303   // referent object.
5304   //
5305   // We need to explicitly copy these referent objects - the references
5306   // will be processed at the end of remarking.
5307   //
5308   // We also need to do this copying before we process the reference
5309   // objects discovered by the STW ref processor in case one of these
5310   // referents points to another object which is also referenced by an
5311   // object discovered by the STW ref processor.
5312 
5313   int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5314                         workers()->active_workers() : 1);
5315 
5316   assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5317            active_workers == workers()->active_workers(),
5318            "Need to reset active_workers");
5319 
5320   set_par_threads(active_workers);
5321   G1ParPreserveCMReferentsTask keep_cm_referents(this, active_workers, _task_queues);
5322 
5323   if (G1CollectedHeap::use_parallel_gc_threads()) {
5324     workers()->run_task(&keep_cm_referents);
5325   } else {
5326     keep_cm_referents.work(0);
5327   }
5328 
5329   set_par_threads(0);
5330 
5331   // Closure to test whether a referent is alive.
5332   G1STWIsAliveClosure is_alive(this);
5333 
5334   // Even when parallel reference processing is enabled, the processing
5335   // of JNI refs is serial and performed serially by the current thread
5336   // rather than by a worker. The following PSS will be used for processing
5337   // JNI refs.
5338 
5339   // Use only a single queue for this PSS.
5340   G1ParScanThreadState pss(this, 0);
5341 
5342   // We do not embed a reference processor in the copying/scanning
5343   // closures while we're actually processing the discovered
5344   // reference objects.
5345   G1ParScanHeapEvacClosure        scan_evac_cl(this, &pss, NULL);
5346   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5347   G1ParScanPartialArrayClosure    partial_scan_cl(this, &pss, NULL);
5348 
5349   pss.set_evac_closure(&scan_evac_cl);
5350   pss.set_evac_failure_closure(&evac_failure_cl);
5351   pss.set_partial_scan_closure(&partial_scan_cl);
5352 
5353   assert(pss.refs()->is_empty(), "pre-condition");
5354 
5355   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5356   G1ParScanPermClosure           only_copy_perm_cl(this, &pss, NULL);
5357 
5358   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5359   G1ParScanAndMarkPermClosure    copy_mark_perm_cl(this, &pss, NULL);
5360 
5361   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5362   OopsInHeapRegionClosure*       copy_perm_cl = &only_copy_perm_cl;
5363 
5364   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5365     // We also need to mark copied objects.
5366     copy_non_heap_cl = &copy_mark_non_heap_cl;
5367     copy_perm_cl = &copy_mark_perm_cl;
5368   }
5369 
5370   // Keep alive closure.
5371   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_perm_cl, &pss);
5372 
5373   // Serial Complete GC closure
5374   G1STWDrainQueueClosure drain_queue(this, &pss);
5375 
5376   // Setup the soft refs policy...
5377   rp->setup_policy(false);
5378 
5379   if (!rp->processing_is_mt()) {
5380     // Serial reference processing...
5381     rp->process_discovered_references(&is_alive,
5382                                       &keep_alive,
5383                                       &drain_queue,
5384                                       NULL);
5385   } else {
5386     // Parallel reference processing
5387     assert(rp->num_q() == active_workers, "sanity");
5388     assert(active_workers <= rp->max_num_q(), "sanity");
5389 
5390     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, active_workers);
5391     rp->process_discovered_references(&is_alive, &keep_alive, &drain_queue, &par_task_executor);
5392   }
5393 
5394   // We have completed copying any necessary live referent objects
5395   // (that were not copied during the actual pause) so we can
5396   // retire any active alloc buffers
5397   pss.retire_alloc_buffers();
5398   assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5399 
5400   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5401   g1_policy()->record_ref_proc_time(ref_proc_time * 1000.0);
5402 }
5403 
5404 // Weak Reference processing during an evacuation pause (part 2).
5405 void G1CollectedHeap::enqueue_discovered_references() {
5406   double ref_enq_start = os::elapsedTime();
5407 
5408   ReferenceProcessor* rp = _ref_processor_stw;
5409   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5410 
5411   // Now enqueue any remaining on the discovered lists on to
5412   // the pending list.
5413   if (!rp->processing_is_mt()) {
5414     // Serial reference processing...
5415     rp->enqueue_discovered_references();
5416   } else {
5417     // Parallel reference enqueuing
5418 
5419     int active_workers = (ParallelGCThreads > 0 ? workers()->active_workers() : 1);
5420     assert(active_workers == workers()->active_workers(),
5421            "Need to reset active_workers");
5422     assert(rp->num_q() == active_workers, "sanity");
5423     assert(active_workers <= rp->max_num_q(), "sanity");
5424 
5425     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, active_workers);
5426     rp->enqueue_discovered_references(&par_task_executor);
5427   }
5428 
5429   rp->verify_no_references_recorded();
5430   assert(!rp->discovery_enabled(), "should have been disabled");
5431 
5432   // FIXME
5433   // CM's reference processing also cleans up the string and symbol tables.
5434   // Should we do that here also? We could, but it is a serial operation
5435   // and could signicantly increase the pause time.
5436 
5437   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5438   g1_policy()->record_ref_enq_time(ref_enq_time * 1000.0);
5439 }
5440 
5441 void G1CollectedHeap::evacuate_collection_set() {
5442   set_evacuation_failed(false);
5443 
5444   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5445   concurrent_g1_refine()->set_use_cache(false);
5446   concurrent_g1_refine()->clear_hot_cache_claimed_index();
5447 
5448   int n_workers;
5449   if (G1CollectedHeap::use_parallel_gc_threads()) {
5450     n_workers =
5451       AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5452                                      workers()->active_workers(),
5453                                      Threads::number_of_non_daemon_threads());
5454     assert(UseDynamicNumberOfGCThreads ||
5455            n_workers == workers()->total_workers(),
5456            "If not dynamic should be using all the  workers");
5457     workers()->set_active_workers(n_workers);
5458     set_par_threads(n_workers);
5459   } else {
5460     assert(n_par_threads() == 0,
5461            "Should be the original non-parallel value");
5462     n_workers = 1;
5463   }
5464 
5465   G1ParTask g1_par_task(this, _task_queues);
5466 
5467   init_for_evac_failure(NULL);
5468 
5469   rem_set()->prepare_for_younger_refs_iterate(true);
5470 
5471   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5472   double start_par = os::elapsedTime();
5473 
5474   if (G1CollectedHeap::use_parallel_gc_threads()) {
5475     // The individual threads will set their evac-failure closures.
5476     StrongRootsScope srs(this);
5477     if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5478     // These tasks use ShareHeap::_process_strong_tasks
5479     assert(UseDynamicNumberOfGCThreads ||
5480            workers()->active_workers() == workers()->total_workers(),
5481            "If not dynamic should be using all the  workers");
5482     workers()->run_task(&g1_par_task);
5483   } else {
5484     StrongRootsScope srs(this);
5485     g1_par_task.set_for_termination(n_workers);
5486     g1_par_task.work(0);
5487   }
5488 
5489   double par_time = (os::elapsedTime() - start_par) * 1000.0;
5490   g1_policy()->record_par_time(par_time);
5491 
5492   set_par_threads(0);
5493 
5494   // Process any discovered reference objects - we have
5495   // to do this _before_ we retire the GC alloc regions
5496   // as we may have to copy some 'reachable' referent
5497   // objects (and their reachable sub-graphs) that were
5498   // not copied during the pause.
5499   process_discovered_references();
5500 
5501   // Weak root processing.
5502   // Note: when JSR 292 is enabled and code blobs can contain
5503   // non-perm oops then we will need to process the code blobs
5504   // here too.
5505   {
5506     G1STWIsAliveClosure is_alive(this);
5507     G1KeepAliveClosure keep_alive(this);
5508     JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5509   }
5510 
5511   release_gc_alloc_regions();
5512   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5513 
5514   concurrent_g1_refine()->clear_hot_cache();
5515   concurrent_g1_refine()->set_use_cache(true);
5516 
5517   finalize_for_evac_failure();
5518 
5519   // Must do this before clearing the per-region evac-failure flags
5520   // (which is currently done when we free the collection set).
5521   // We also only do this if marking is actually in progress and so
5522   // have to do this before we set the mark_in_progress flag at the
5523   // end of an initial mark pause.
5524   concurrent_mark()->complete_marking_in_collection_set();
5525 
5526   if (evacuation_failed()) {
5527     remove_self_forwarding_pointers();
5528     if (PrintGCDetails) {
5529       gclog_or_tty->print(" (to-space overflow)");
5530     } else if (PrintGC) {
5531       gclog_or_tty->print("--");
5532     }
5533   }
5534 
5535   // Enqueue any remaining references remaining on the STW
5536   // reference processor's discovered lists. We need to do
5537   // this after the card table is cleaned (and verified) as
5538   // the act of enqueuing entries on to the pending list
5539   // will log these updates (and dirty their associated
5540   // cards). We need these updates logged to update any
5541   // RSets.
5542   enqueue_discovered_references();
5543 
5544   if (G1DeferredRSUpdate) {
5545     RedirtyLoggedCardTableEntryFastClosure redirty;
5546     dirty_card_queue_set().set_closure(&redirty);
5547     dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5548 
5549     DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5550     dcq.merge_bufferlists(&dirty_card_queue_set());
5551     assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5552   }
5553   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5554 }
5555 
5556 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5557                                      size_t* pre_used,
5558                                      FreeRegionList* free_list,
5559                                      OldRegionSet* old_proxy_set,
5560                                      HumongousRegionSet* humongous_proxy_set,
5561                                      HRRSCleanupTask* hrrs_cleanup_task,
5562                                      bool par) {
5563   if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5564     if (hr->isHumongous()) {
5565       assert(hr->startsHumongous(), "we should only see starts humongous");
5566       free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5567     } else {
5568       _old_set.remove_with_proxy(hr, old_proxy_set);
5569       free_region(hr, pre_used, free_list, par);
5570     }
5571   } else {
5572     hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5573   }
5574 }
5575 
5576 void G1CollectedHeap::free_region(HeapRegion* hr,
5577                                   size_t* pre_used,
5578                                   FreeRegionList* free_list,
5579                                   bool par) {
5580   assert(!hr->isHumongous(), "this is only for non-humongous regions");
5581   assert(!hr->is_empty(), "the region should not be empty");
5582   assert(free_list != NULL, "pre-condition");
5583 
5584   *pre_used += hr->used();
5585   hr->hr_clear(par, true /* clear_space */);
5586   free_list->add_as_head(hr);
5587 }
5588 
5589 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5590                                      size_t* pre_used,
5591                                      FreeRegionList* free_list,
5592                                      HumongousRegionSet* humongous_proxy_set,
5593                                      bool par) {
5594   assert(hr->startsHumongous(), "this is only for starts humongous regions");
5595   assert(free_list != NULL, "pre-condition");
5596   assert(humongous_proxy_set != NULL, "pre-condition");
5597 
5598   size_t hr_used = hr->used();
5599   size_t hr_capacity = hr->capacity();
5600   size_t hr_pre_used = 0;
5601   _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5602   hr->set_notHumongous();
5603   free_region(hr, &hr_pre_used, free_list, par);
5604 
5605   size_t i = hr->hrs_index() + 1;
5606   size_t num = 1;
5607   while (i < n_regions()) {
5608     HeapRegion* curr_hr = region_at(i);
5609     if (!curr_hr->continuesHumongous()) {
5610       break;
5611     }
5612     curr_hr->set_notHumongous();
5613     free_region(curr_hr, &hr_pre_used, free_list, par);
5614     num += 1;
5615     i += 1;
5616   }
5617   assert(hr_pre_used == hr_used,
5618          err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5619                  "should be the same", hr_pre_used, hr_used));
5620   *pre_used += hr_pre_used;
5621 }
5622 
5623 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5624                                        FreeRegionList* free_list,
5625                                        OldRegionSet* old_proxy_set,
5626                                        HumongousRegionSet* humongous_proxy_set,
5627                                        bool par) {
5628   if (pre_used > 0) {
5629     Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5630     MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5631     assert(_summary_bytes_used >= pre_used,
5632            err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5633                    "should be >= pre_used: "SIZE_FORMAT,
5634                    _summary_bytes_used, pre_used));
5635     _summary_bytes_used -= pre_used;
5636   }
5637   if (free_list != NULL && !free_list->is_empty()) {
5638     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5639     _free_list.add_as_head(free_list);
5640   }
5641   if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5642     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5643     _old_set.update_from_proxy(old_proxy_set);
5644   }
5645   if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5646     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5647     _humongous_set.update_from_proxy(humongous_proxy_set);
5648   }
5649 }
5650 
5651 class G1ParCleanupCTTask : public AbstractGangTask {
5652   CardTableModRefBS* _ct_bs;
5653   G1CollectedHeap* _g1h;
5654   HeapRegion* volatile _su_head;
5655 public:
5656   G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5657                      G1CollectedHeap* g1h) :
5658     AbstractGangTask("G1 Par Cleanup CT Task"),
5659     _ct_bs(ct_bs), _g1h(g1h) { }
5660 
5661   void work(int i) {
5662     HeapRegion* r;
5663     while (r = _g1h->pop_dirty_cards_region()) {
5664       clear_cards(r);
5665     }
5666   }
5667 
5668   void clear_cards(HeapRegion* r) {
5669     // Cards of the survivors should have already been dirtied.
5670     if (!r->is_survivor()) {
5671       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5672     }
5673   }
5674 };
5675 
5676 #ifndef PRODUCT
5677 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5678   G1CollectedHeap* _g1h;
5679   CardTableModRefBS* _ct_bs;
5680 public:
5681   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5682     : _g1h(g1h), _ct_bs(ct_bs) { }
5683   virtual bool doHeapRegion(HeapRegion* r) {
5684     if (r->is_survivor()) {
5685       _g1h->verify_dirty_region(r);
5686     } else {
5687       _g1h->verify_not_dirty_region(r);
5688     }
5689     return false;
5690   }
5691 };
5692 
5693 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5694   // All of the region should be clean.
5695   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5696   MemRegion mr(hr->bottom(), hr->end());
5697   ct_bs->verify_not_dirty_region(mr);
5698 }
5699 
5700 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5701   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5702   // dirty allocated blocks as they allocate them. The thread that
5703   // retires each region and replaces it with a new one will do a
5704   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5705   // not dirty that area (one less thing to have to do while holding
5706   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5707   // is dirty.
5708   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5709   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5710   ct_bs->verify_dirty_region(mr);
5711 }
5712 
5713 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5714   CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5715   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5716     verify_dirty_region(hr);
5717   }
5718 }
5719 
5720 void G1CollectedHeap::verify_dirty_young_regions() {
5721   verify_dirty_young_list(_young_list->first_region());
5722   verify_dirty_young_list(_young_list->first_survivor_region());
5723 }
5724 #endif
5725 
5726 void G1CollectedHeap::cleanUpCardTable() {
5727   CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5728   double start = os::elapsedTime();
5729 
5730   {
5731     // Iterate over the dirty cards region list.
5732     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5733 
5734     if (G1CollectedHeap::use_parallel_gc_threads()) {
5735       set_par_threads();
5736       workers()->run_task(&cleanup_task);
5737       set_par_threads(0);
5738     } else {
5739       while (_dirty_cards_region_list) {
5740         HeapRegion* r = _dirty_cards_region_list;
5741         cleanup_task.clear_cards(r);
5742         _dirty_cards_region_list = r->get_next_dirty_cards_region();
5743         if (_dirty_cards_region_list == r) {
5744           // The last region.
5745           _dirty_cards_region_list = NULL;
5746         }
5747         r->set_next_dirty_cards_region(NULL);
5748       }
5749     }
5750 #ifndef PRODUCT
5751     if (G1VerifyCTCleanup || VerifyAfterGC) {
5752       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5753       heap_region_iterate(&cleanup_verifier);
5754     }
5755 #endif
5756   }
5757 
5758   double elapsed = os::elapsedTime() - start;
5759   g1_policy()->record_clear_ct_time(elapsed * 1000.0);
5760 }
5761 
5762 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
5763   size_t pre_used = 0;
5764   FreeRegionList local_free_list("Local List for CSet Freeing");
5765 
5766   double young_time_ms     = 0.0;
5767   double non_young_time_ms = 0.0;
5768 
5769   // Since the collection set is a superset of the the young list,
5770   // all we need to do to clear the young list is clear its
5771   // head and length, and unlink any young regions in the code below
5772   _young_list->clear();
5773 
5774   G1CollectorPolicy* policy = g1_policy();
5775 
5776   double start_sec = os::elapsedTime();
5777   bool non_young = true;
5778 
5779   HeapRegion* cur = cs_head;
5780   int age_bound = -1;
5781   size_t rs_lengths = 0;
5782 
5783   while (cur != NULL) {
5784     assert(!is_on_master_free_list(cur), "sanity");
5785     if (non_young) {
5786       if (cur->is_young()) {
5787         double end_sec = os::elapsedTime();
5788         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5789         non_young_time_ms += elapsed_ms;
5790 
5791         start_sec = os::elapsedTime();
5792         non_young = false;
5793       }
5794     } else {
5795       if (!cur->is_young()) {
5796         double end_sec = os::elapsedTime();
5797         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5798         young_time_ms += elapsed_ms;
5799 
5800         start_sec = os::elapsedTime();
5801         non_young = true;
5802       }
5803     }
5804 
5805     rs_lengths += cur->rem_set()->occupied();
5806 
5807     HeapRegion* next = cur->next_in_collection_set();
5808     assert(cur->in_collection_set(), "bad CS");
5809     cur->set_next_in_collection_set(NULL);
5810     cur->set_in_collection_set(false);
5811 
5812     if (cur->is_young()) {
5813       int index = cur->young_index_in_cset();
5814       assert(index != -1, "invariant");
5815       assert((size_t) index < policy->young_cset_region_length(), "invariant");
5816       size_t words_survived = _surviving_young_words[index];
5817       cur->record_surv_words_in_group(words_survived);
5818 
5819       // At this point the we have 'popped' cur from the collection set
5820       // (linked via next_in_collection_set()) but it is still in the
5821       // young list (linked via next_young_region()). Clear the
5822       // _next_young_region field.
5823       cur->set_next_young_region(NULL);
5824     } else {
5825       int index = cur->young_index_in_cset();
5826       assert(index == -1, "invariant");
5827     }
5828 
5829     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5830             (!cur->is_young() && cur->young_index_in_cset() == -1),
5831             "invariant" );
5832 
5833     if (!cur->evacuation_failed()) {
5834       MemRegion used_mr = cur->used_region();
5835 
5836       // And the region is empty.
5837       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5838 
5839       // If marking is in progress then clear any objects marked in
5840       // the current region. Note mark_in_progress() returns false,
5841       // even during an initial mark pause, until the set_marking_started()
5842       // call which takes place later in the pause.
5843       if (mark_in_progress()) {
5844         assert(!g1_policy()->during_initial_mark_pause(), "sanity");
5845         _cm->nextMarkBitMap()->clearRange(used_mr);
5846       }
5847 
5848       free_region(cur, &pre_used, &local_free_list, false /* par */);
5849     } else {
5850       cur->uninstall_surv_rate_group();
5851       if (cur->is_young()) {
5852         cur->set_young_index_in_cset(-1);
5853       }
5854       cur->set_not_young();
5855       cur->set_evacuation_failed(false);
5856       // The region is now considered to be old.
5857       _old_set.add(cur);
5858     }
5859     cur = next;
5860   }
5861 
5862   policy->record_max_rs_lengths(rs_lengths);
5863   policy->cset_regions_freed();
5864 
5865   double end_sec = os::elapsedTime();
5866   double elapsed_ms = (end_sec - start_sec) * 1000.0;
5867 
5868   if (non_young) {
5869     non_young_time_ms += elapsed_ms;
5870   } else {
5871     young_time_ms += elapsed_ms;
5872   }
5873 
5874   update_sets_after_freeing_regions(pre_used, &local_free_list,
5875                                     NULL /* old_proxy_set */,
5876                                     NULL /* humongous_proxy_set */,
5877                                     false /* par */);
5878   policy->record_young_free_cset_time_ms(young_time_ms);
5879   policy->record_non_young_free_cset_time_ms(non_young_time_ms);
5880 }
5881 
5882 // This routine is similar to the above but does not record
5883 // any policy statistics or update free lists; we are abandoning
5884 // the current incremental collection set in preparation of a
5885 // full collection. After the full GC we will start to build up
5886 // the incremental collection set again.
5887 // This is only called when we're doing a full collection
5888 // and is immediately followed by the tearing down of the young list.
5889 
5890 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5891   HeapRegion* cur = cs_head;
5892 
5893   while (cur != NULL) {
5894     HeapRegion* next = cur->next_in_collection_set();
5895     assert(cur->in_collection_set(), "bad CS");
5896     cur->set_next_in_collection_set(NULL);
5897     cur->set_in_collection_set(false);
5898     cur->set_young_index_in_cset(-1);
5899     cur = next;
5900   }
5901 }
5902 
5903 void G1CollectedHeap::set_free_regions_coming() {
5904   if (G1ConcRegionFreeingVerbose) {
5905     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5906                            "setting free regions coming");
5907   }
5908 
5909   assert(!free_regions_coming(), "pre-condition");
5910   _free_regions_coming = true;
5911 }
5912 
5913 void G1CollectedHeap::reset_free_regions_coming() {
5914   {
5915     assert(free_regions_coming(), "pre-condition");
5916     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5917     _free_regions_coming = false;
5918     SecondaryFreeList_lock->notify_all();
5919   }
5920 
5921   if (G1ConcRegionFreeingVerbose) {
5922     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5923                            "reset free regions coming");
5924   }
5925 }
5926 
5927 void G1CollectedHeap::wait_while_free_regions_coming() {
5928   // Most of the time we won't have to wait, so let's do a quick test
5929   // first before we take the lock.
5930   if (!free_regions_coming()) {
5931     return;
5932   }
5933 
5934   if (G1ConcRegionFreeingVerbose) {
5935     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5936                            "waiting for free regions");
5937   }
5938 
5939   {
5940     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5941     while (free_regions_coming()) {
5942       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5943     }
5944   }
5945 
5946   if (G1ConcRegionFreeingVerbose) {
5947     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5948                            "done waiting for free regions");
5949   }
5950 }
5951 
5952 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5953   assert(heap_lock_held_for_gc(),
5954               "the heap lock should already be held by or for this thread");
5955   _young_list->push_region(hr);
5956 }
5957 
5958 class NoYoungRegionsClosure: public HeapRegionClosure {
5959 private:
5960   bool _success;
5961 public:
5962   NoYoungRegionsClosure() : _success(true) { }
5963   bool doHeapRegion(HeapRegion* r) {
5964     if (r->is_young()) {
5965       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5966                              r->bottom(), r->end());
5967       _success = false;
5968     }
5969     return false;
5970   }
5971   bool success() { return _success; }
5972 };
5973 
5974 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5975   bool ret = _young_list->check_list_empty(check_sample);
5976 
5977   if (check_heap) {
5978     NoYoungRegionsClosure closure;
5979     heap_region_iterate(&closure);
5980     ret = ret && closure.success();
5981   }
5982 
5983   return ret;
5984 }
5985 
5986 class TearDownRegionSetsClosure : public HeapRegionClosure {
5987 private:
5988   OldRegionSet *_old_set;
5989 
5990 public:
5991   TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
5992 
5993   bool doHeapRegion(HeapRegion* r) {
5994     if (r->is_empty()) {
5995       // We ignore empty regions, we'll empty the free list afterwards
5996     } else if (r->is_young()) {
5997       // We ignore young regions, we'll empty the young list afterwards
5998     } else if (r->isHumongous()) {
5999       // We ignore humongous regions, we're not tearing down the
6000       // humongous region set
6001     } else {
6002       // The rest should be old
6003       _old_set->remove(r);
6004     }
6005     return false;
6006   }
6007 
6008   ~TearDownRegionSetsClosure() {
6009     assert(_old_set->is_empty(), "post-condition");
6010   }
6011 };
6012 
6013 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6014   assert_at_safepoint(true /* should_be_vm_thread */);
6015 
6016   if (!free_list_only) {
6017     TearDownRegionSetsClosure cl(&_old_set);
6018     heap_region_iterate(&cl);
6019 
6020     // Need to do this after the heap iteration to be able to
6021     // recognize the young regions and ignore them during the iteration.
6022     _young_list->empty_list();
6023   }
6024   _free_list.remove_all();
6025 }
6026 
6027 class RebuildRegionSetsClosure : public HeapRegionClosure {
6028 private:
6029   bool            _free_list_only;
6030   OldRegionSet*   _old_set;
6031   FreeRegionList* _free_list;
6032   size_t          _total_used;
6033 
6034 public:
6035   RebuildRegionSetsClosure(bool free_list_only,
6036                            OldRegionSet* old_set, FreeRegionList* free_list) :
6037     _free_list_only(free_list_only),
6038     _old_set(old_set), _free_list(free_list), _total_used(0) {
6039     assert(_free_list->is_empty(), "pre-condition");
6040     if (!free_list_only) {
6041       assert(_old_set->is_empty(), "pre-condition");
6042     }
6043   }
6044 
6045   bool doHeapRegion(HeapRegion* r) {
6046     if (r->continuesHumongous()) {
6047       return false;
6048     }
6049 
6050     if (r->is_empty()) {
6051       // Add free regions to the free list
6052       _free_list->add_as_tail(r);
6053     } else if (!_free_list_only) {
6054       assert(!r->is_young(), "we should not come across young regions");
6055 
6056       if (r->isHumongous()) {
6057         // We ignore humongous regions, we left the humongous set unchanged
6058       } else {
6059         // The rest should be old, add them to the old set
6060         _old_set->add(r);
6061       }
6062       _total_used += r->used();
6063     }
6064 
6065     return false;
6066   }
6067 
6068   size_t total_used() {
6069     return _total_used;
6070   }
6071 };
6072 
6073 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6074   assert_at_safepoint(true /* should_be_vm_thread */);
6075 
6076   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6077   heap_region_iterate(&cl);
6078 
6079   if (!free_list_only) {
6080     _summary_bytes_used = cl.total_used();
6081   }
6082   assert(_summary_bytes_used == recalculate_used(),
6083          err_msg("inconsistent _summary_bytes_used, "
6084                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6085                  _summary_bytes_used, recalculate_used()));
6086 }
6087 
6088 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6089   _refine_cte_cl->set_concurrent(concurrent);
6090 }
6091 
6092 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6093   HeapRegion* hr = heap_region_containing(p);
6094   if (hr == NULL) {
6095     return is_in_permanent(p);
6096   } else {
6097     return hr->is_in(p);
6098   }
6099 }
6100 
6101 // Methods for the mutator alloc region
6102 
6103 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6104                                                       bool force) {
6105   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6106   assert(!force || g1_policy()->can_expand_young_list(),
6107          "if force is true we should be able to expand the young list");
6108   bool young_list_full = g1_policy()->is_young_list_full();
6109   if (force || !young_list_full) {
6110     HeapRegion* new_alloc_region = new_region(word_size,
6111                                               false /* do_expand */);
6112     if (new_alloc_region != NULL) {
6113       set_region_short_lived_locked(new_alloc_region);
6114       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6115       return new_alloc_region;
6116     }
6117   }
6118   return NULL;
6119 }
6120 
6121 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6122                                                   size_t allocated_bytes) {
6123   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6124   assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6125 
6126   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6127   _summary_bytes_used += allocated_bytes;
6128   _hr_printer.retire(alloc_region);
6129   // We update the eden sizes here, when the region is retired,
6130   // instead of when it's allocated, since this is the point that its
6131   // used space has been recored in _summary_bytes_used.
6132   g1mm()->update_eden_size();
6133 }
6134 
6135 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6136                                                     bool force) {
6137   return _g1h->new_mutator_alloc_region(word_size, force);
6138 }
6139 
6140 void G1CollectedHeap::set_par_threads() {
6141   // Don't change the number of workers.  Use the value previously set
6142   // in the workgroup.
6143   assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6144   int n_workers = workers()->active_workers();
6145   assert(UseDynamicNumberOfGCThreads ||
6146            n_workers == workers()->total_workers(),
6147       "Otherwise should be using the total number of workers");
6148   if (n_workers == 0) {
6149     assert(false, "Should have been set in prior evacuation pause.");
6150     n_workers = ParallelGCThreads;
6151     workers()->set_active_workers(n_workers);
6152   }
6153   set_par_threads(n_workers);
6154 }
6155 
6156 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6157                                        size_t allocated_bytes) {
6158   _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6159 }
6160 
6161 // Methods for the GC alloc regions
6162 
6163 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6164                                                  size_t count,
6165                                                  GCAllocPurpose ap) {
6166   assert(FreeList_lock->owned_by_self(), "pre-condition");
6167 
6168   if (count < g1_policy()->max_regions(ap)) {
6169     HeapRegion* new_alloc_region = new_region(word_size,
6170                                               true /* do_expand */);
6171     if (new_alloc_region != NULL) {
6172       // We really only need to do this for old regions given that we
6173       // should never scan survivors. But it doesn't hurt to do it
6174       // for survivors too.
6175       new_alloc_region->set_saved_mark();
6176       if (ap == GCAllocForSurvived) {
6177         new_alloc_region->set_survivor();
6178         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6179       } else {
6180         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6181       }
6182       return new_alloc_region;
6183     } else {
6184       g1_policy()->note_alloc_region_limit_reached(ap);
6185     }
6186   }
6187   return NULL;
6188 }
6189 
6190 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6191                                              size_t allocated_bytes,
6192                                              GCAllocPurpose ap) {
6193   alloc_region->note_end_of_copying();
6194   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6195   if (ap == GCAllocForSurvived) {
6196     young_list()->add_survivor_region(alloc_region);
6197   } else {
6198     _old_set.add(alloc_region);
6199   }
6200   _hr_printer.retire(alloc_region);
6201 }
6202 
6203 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6204                                                        bool force) {
6205   assert(!force, "not supported for GC alloc regions");
6206   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6207 }
6208 
6209 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6210                                           size_t allocated_bytes) {
6211   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6212                                GCAllocForSurvived);
6213 }
6214 
6215 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6216                                                   bool force) {
6217   assert(!force, "not supported for GC alloc regions");
6218   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6219 }
6220 
6221 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6222                                      size_t allocated_bytes) {
6223   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6224                                GCAllocForTenured);
6225 }
6226 // Heap region set verification
6227 
6228 class VerifyRegionListsClosure : public HeapRegionClosure {
6229 private:
6230   FreeRegionList*     _free_list;
6231   OldRegionSet*       _old_set;
6232   HumongousRegionSet* _humongous_set;
6233   size_t              _region_count;
6234 
6235 public:
6236   VerifyRegionListsClosure(OldRegionSet* old_set,
6237                            HumongousRegionSet* humongous_set,
6238                            FreeRegionList* free_list) :
6239     _old_set(old_set), _humongous_set(humongous_set),
6240     _free_list(free_list), _region_count(0) { }
6241 
6242   size_t region_count()      { return _region_count;      }
6243 
6244   bool doHeapRegion(HeapRegion* hr) {
6245     _region_count += 1;
6246 
6247     if (hr->continuesHumongous()) {
6248       return false;
6249     }
6250 
6251     if (hr->is_young()) {
6252       // TODO
6253     } else if (hr->startsHumongous()) {
6254       _humongous_set->verify_next_region(hr);
6255     } else if (hr->is_empty()) {
6256       _free_list->verify_next_region(hr);
6257     } else {
6258       _old_set->verify_next_region(hr);
6259     }
6260     return false;
6261   }
6262 };
6263 
6264 HeapRegion* G1CollectedHeap::new_heap_region(size_t hrs_index,
6265                                              HeapWord* bottom) {
6266   HeapWord* end = bottom + HeapRegion::GrainWords;
6267   MemRegion mr(bottom, end);
6268   assert(_g1_reserved.contains(mr), "invariant");
6269   // This might return NULL if the allocation fails
6270   return new HeapRegion(hrs_index, _bot_shared, mr, true /* is_zeroed */);
6271 }
6272 
6273 void G1CollectedHeap::verify_region_sets() {
6274   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6275 
6276   // First, check the explicit lists.
6277   _free_list.verify();
6278   {
6279     // Given that a concurrent operation might be adding regions to
6280     // the secondary free list we have to take the lock before
6281     // verifying it.
6282     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6283     _secondary_free_list.verify();
6284   }
6285   _old_set.verify();
6286   _humongous_set.verify();
6287 
6288   // If a concurrent region freeing operation is in progress it will
6289   // be difficult to correctly attributed any free regions we come
6290   // across to the correct free list given that they might belong to
6291   // one of several (free_list, secondary_free_list, any local lists,
6292   // etc.). So, if that's the case we will skip the rest of the
6293   // verification operation. Alternatively, waiting for the concurrent
6294   // operation to complete will have a non-trivial effect on the GC's
6295   // operation (no concurrent operation will last longer than the
6296   // interval between two calls to verification) and it might hide
6297   // any issues that we would like to catch during testing.
6298   if (free_regions_coming()) {
6299     return;
6300   }
6301 
6302   // Make sure we append the secondary_free_list on the free_list so
6303   // that all free regions we will come across can be safely
6304   // attributed to the free_list.
6305   append_secondary_free_list_if_not_empty_with_lock();
6306 
6307   // Finally, make sure that the region accounting in the lists is
6308   // consistent with what we see in the heap.
6309   _old_set.verify_start();
6310   _humongous_set.verify_start();
6311   _free_list.verify_start();
6312 
6313   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6314   heap_region_iterate(&cl);
6315 
6316   _old_set.verify_end();
6317   _humongous_set.verify_end();
6318   _free_list.verify_end();
6319 }