rev 13232 : imported patch parallel-fullgc-stefanj
rev 13237 : imported patch 8183226-periodic-rem-set-summary-accesses-uninitialized-stuff
rev 13238 : imported patch 8183226-eridk-sjohanss-review
rev 13240 : imported patch 8183128-cleanup-refinecardtableentryclosure
rev 13241 : imported patch 8183128-erikd-review
rev 13243 : [mq]: 8183121-add-information-about-scanned-skipped-cards-during-updaters

   1 /*
   2  * Copyright (c) 2001, 2017, 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 "classfile/metadataOnStackMark.hpp"
  27 #include "classfile/stringTable.hpp"
  28 #include "classfile/symbolTable.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "gc/g1/bufferingOopClosure.hpp"
  32 #include "gc/g1/concurrentG1Refine.hpp"
  33 #include "gc/g1/concurrentG1RefineThread.hpp"
  34 #include "gc/g1/concurrentMarkThread.inline.hpp"
  35 #include "gc/g1/g1Allocator.inline.hpp"
  36 #include "gc/g1/g1CollectedHeap.inline.hpp"
  37 #include "gc/g1/g1CollectionSet.hpp"
  38 #include "gc/g1/g1CollectorPolicy.hpp"
  39 #include "gc/g1/g1CollectorState.hpp"
  40 #include "gc/g1/g1EvacStats.inline.hpp"
  41 #include "gc/g1/g1FullCollector.hpp"
  42 #include "gc/g1/g1FullGCScope.hpp"
  43 #include "gc/g1/g1GCPhaseTimes.hpp"
  44 #include "gc/g1/g1HeapSizingPolicy.hpp"
  45 #include "gc/g1/g1HeapTransition.hpp"
  46 #include "gc/g1/g1HeapVerifier.hpp"
  47 #include "gc/g1/g1HotCardCache.hpp"
  48 #include "gc/g1/g1OopClosures.inline.hpp"
  49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  50 #include "gc/g1/g1Policy.hpp"
  51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  52 #include "gc/g1/g1RemSet.inline.hpp"
  53 #include "gc/g1/g1RootClosures.hpp"
  54 #include "gc/g1/g1RootProcessor.hpp"
  55 #include "gc/g1/g1StringDedup.hpp"
  56 #include "gc/g1/g1YCTypes.hpp"
  57 #include "gc/g1/heapRegion.inline.hpp"
  58 #include "gc/g1/heapRegionRemSet.hpp"
  59 #include "gc/g1/heapRegionSet.inline.hpp"
  60 #include "gc/g1/suspendibleThreadSet.hpp"
  61 #include "gc/g1/vm_operations_g1.hpp"
  62 #include "gc/shared/gcHeapSummary.hpp"
  63 #include "gc/shared/gcId.hpp"
  64 #include "gc/shared/gcLocker.inline.hpp"
  65 #include "gc/shared/gcTimer.hpp"
  66 #include "gc/shared/gcTrace.hpp"
  67 #include "gc/shared/gcTraceTime.inline.hpp"
  68 #include "gc/shared/generationSpec.hpp"
  69 #include "gc/shared/isGCActiveMark.hpp"
  70 #include "gc/shared/preservedMarks.inline.hpp"
  71 #include "gc/shared/referenceProcessor.inline.hpp"
  72 #include "gc/shared/taskqueue.inline.hpp"
  73 #include "logging/log.hpp"
  74 #include "memory/allocation.hpp"
  75 #include "memory/iterator.hpp"
  76 #include "memory/resourceArea.hpp"
  77 #include "oops/oop.inline.hpp"
  78 #include "prims/resolvedMethodTable.hpp"
  79 #include "runtime/atomic.hpp"
  80 #include "runtime/init.hpp"
  81 #include "runtime/orderAccess.inline.hpp"
  82 #include "runtime/vmThread.hpp"
  83 #include "utilities/align.hpp"
  84 #include "utilities/globalDefinitions.hpp"
  85 #include "utilities/stack.inline.hpp"
  86 
  87 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  88 
  89 // INVARIANTS/NOTES
  90 //
  91 // All allocation activity covered by the G1CollectedHeap interface is
  92 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  93 // and allocate_new_tlab, which are the "entry" points to the
  94 // allocation code from the rest of the JVM.  (Note that this does not
  95 // apply to TLAB allocation, which is not part of this interface: it
  96 // is done by clients of this interface.)
  97 
  98 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
  99  private:
 100   size_t _num_dirtied;
 101   G1CollectedHeap* _g1h;
 102   G1SATBCardTableLoggingModRefBS* _g1_bs;
 103 
 104   HeapRegion* region_for_card(jbyte* card_ptr) const {
 105     return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
 106   }
 107 
 108   bool will_become_free(HeapRegion* hr) const {
 109     // A region will be freed by free_collection_set if the region is in the
 110     // collection set and has not had an evacuation failure.
 111     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 112   }
 113 
 114  public:
 115   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 116     _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
 117 
 118   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 119     HeapRegion* hr = region_for_card(card_ptr);
 120 
 121     // Should only dirty cards in regions that won't be freed.
 122     if (!will_become_free(hr)) {
 123       *card_ptr = CardTableModRefBS::dirty_card_val();
 124       _num_dirtied++;
 125     }
 126 
 127     return true;
 128   }
 129 
 130   size_t num_dirtied()   const { return _num_dirtied; }
 131 };
 132 
 133 
 134 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 135   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 136 }
 137 
 138 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 139   // The from card cache is not the memory that is actually committed. So we cannot
 140   // take advantage of the zero_filled parameter.
 141   reset_from_card_cache(start_idx, num_regions);
 142 }
 143 
 144 // Returns true if the reference points to an object that
 145 // can move in an incremental collection.
 146 bool G1CollectedHeap::is_scavengable(const void* p) {
 147   HeapRegion* hr = heap_region_containing(p);
 148   return !hr->is_pinned();
 149 }
 150 
 151 
 152 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 153                                              MemRegion mr) {
 154   return new HeapRegion(hrs_index, bot(), mr);
 155 }
 156 
 157 // Private methods.
 158 
 159 HeapRegion*
 160 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 161   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 162   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 163     if (!_secondary_free_list.is_empty()) {
 164       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 165                                       "secondary_free_list has %u entries",
 166                                       _secondary_free_list.length());
 167       // It looks as if there are free regions available on the
 168       // secondary_free_list. Let's move them to the free_list and try
 169       // again to allocate from it.
 170       append_secondary_free_list();
 171 
 172       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 173              "empty we should have moved at least one entry to the free_list");
 174       HeapRegion* res = _hrm.allocate_free_region(is_old);
 175       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 176                                       "allocated " HR_FORMAT " from secondary_free_list",
 177                                       HR_FORMAT_PARAMS(res));
 178       return res;
 179     }
 180 
 181     // Wait here until we get notified either when (a) there are no
 182     // more free regions coming or (b) some regions have been moved on
 183     // the secondary_free_list.
 184     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 185   }
 186 
 187   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 188                                   "could not allocate from secondary_free_list");
 189   return NULL;
 190 }
 191 
 192 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 193   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 194          "the only time we use this to allocate a humongous region is "
 195          "when we are allocating a single humongous region");
 196 
 197   HeapRegion* res;
 198   if (G1StressConcRegionFreeing) {
 199     if (!_secondary_free_list.is_empty()) {
 200       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 201                                       "forced to look at the secondary_free_list");
 202       res = new_region_try_secondary_free_list(is_old);
 203       if (res != NULL) {
 204         return res;
 205       }
 206     }
 207   }
 208 
 209   res = _hrm.allocate_free_region(is_old);
 210 
 211   if (res == NULL) {
 212     log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 213                                     "res == NULL, trying the secondary_free_list");
 214     res = new_region_try_secondary_free_list(is_old);
 215   }
 216   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 217     // Currently, only attempts to allocate GC alloc regions set
 218     // do_expand to true. So, we should only reach here during a
 219     // safepoint. If this assumption changes we might have to
 220     // reconsider the use of _expand_heap_after_alloc_failure.
 221     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 222 
 223     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 224                               word_size * HeapWordSize);
 225 
 226     if (expand(word_size * HeapWordSize)) {
 227       // Given that expand() succeeded in expanding the heap, and we
 228       // always expand the heap by an amount aligned to the heap
 229       // region size, the free list should in theory not be empty.
 230       // In either case allocate_free_region() will check for NULL.
 231       res = _hrm.allocate_free_region(is_old);
 232     } else {
 233       _expand_heap_after_alloc_failure = false;
 234     }
 235   }
 236   return res;
 237 }
 238 
 239 HeapWord*
 240 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 241                                                            uint num_regions,
 242                                                            size_t word_size,
 243                                                            AllocationContext_t context) {
 244   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 245   assert(is_humongous(word_size), "word_size should be humongous");
 246   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 247 
 248   // Index of last region in the series.
 249   uint last = first + num_regions - 1;
 250 
 251   // We need to initialize the region(s) we just discovered. This is
 252   // a bit tricky given that it can happen concurrently with
 253   // refinement threads refining cards on these regions and
 254   // potentially wanting to refine the BOT as they are scanning
 255   // those cards (this can happen shortly after a cleanup; see CR
 256   // 6991377). So we have to set up the region(s) carefully and in
 257   // a specific order.
 258 
 259   // The word size sum of all the regions we will allocate.
 260   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 261   assert(word_size <= word_size_sum, "sanity");
 262 
 263   // This will be the "starts humongous" region.
 264   HeapRegion* first_hr = region_at(first);
 265   // The header of the new object will be placed at the bottom of
 266   // the first region.
 267   HeapWord* new_obj = first_hr->bottom();
 268   // This will be the new top of the new object.
 269   HeapWord* obj_top = new_obj + word_size;
 270 
 271   // First, we need to zero the header of the space that we will be
 272   // allocating. When we update top further down, some refinement
 273   // threads might try to scan the region. By zeroing the header we
 274   // ensure that any thread that will try to scan the region will
 275   // come across the zero klass word and bail out.
 276   //
 277   // NOTE: It would not have been correct to have used
 278   // CollectedHeap::fill_with_object() and make the space look like
 279   // an int array. The thread that is doing the allocation will
 280   // later update the object header to a potentially different array
 281   // type and, for a very short period of time, the klass and length
 282   // fields will be inconsistent. This could cause a refinement
 283   // thread to calculate the object size incorrectly.
 284   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 285 
 286   // Next, pad out the unused tail of the last region with filler
 287   // objects, for improved usage accounting.
 288   // How many words we use for filler objects.
 289   size_t word_fill_size = word_size_sum - word_size;
 290 
 291   // How many words memory we "waste" which cannot hold a filler object.
 292   size_t words_not_fillable = 0;
 293 
 294   if (word_fill_size >= min_fill_size()) {
 295     fill_with_objects(obj_top, word_fill_size);
 296   } else if (word_fill_size > 0) {
 297     // We have space to fill, but we cannot fit an object there.
 298     words_not_fillable = word_fill_size;
 299     word_fill_size = 0;
 300   }
 301 
 302   // We will set up the first region as "starts humongous". This
 303   // will also update the BOT covering all the regions to reflect
 304   // that there is a single object that starts at the bottom of the
 305   // first region.
 306   first_hr->set_starts_humongous(obj_top, word_fill_size);
 307   first_hr->set_allocation_context(context);
 308   // Then, if there are any, we will set up the "continues
 309   // humongous" regions.
 310   HeapRegion* hr = NULL;
 311   for (uint i = first + 1; i <= last; ++i) {
 312     hr = region_at(i);
 313     hr->set_continues_humongous(first_hr);
 314     hr->set_allocation_context(context);
 315   }
 316 
 317   // Up to this point no concurrent thread would have been able to
 318   // do any scanning on any region in this series. All the top
 319   // fields still point to bottom, so the intersection between
 320   // [bottom,top] and [card_start,card_end] will be empty. Before we
 321   // update the top fields, we'll do a storestore to make sure that
 322   // no thread sees the update to top before the zeroing of the
 323   // object header and the BOT initialization.
 324   OrderAccess::storestore();
 325 
 326   // Now, we will update the top fields of the "continues humongous"
 327   // regions except the last one.
 328   for (uint i = first; i < last; ++i) {
 329     hr = region_at(i);
 330     hr->set_top(hr->end());
 331   }
 332 
 333   hr = region_at(last);
 334   // If we cannot fit a filler object, we must set top to the end
 335   // of the humongous object, otherwise we cannot iterate the heap
 336   // and the BOT will not be complete.
 337   hr->set_top(hr->end() - words_not_fillable);
 338 
 339   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 340          "obj_top should be in last region");
 341 
 342   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 343 
 344   assert(words_not_fillable == 0 ||
 345          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 346          "Miscalculation in humongous allocation");
 347 
 348   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 349 
 350   for (uint i = first; i <= last; ++i) {
 351     hr = region_at(i);
 352     _humongous_set.add(hr);
 353     _hr_printer.alloc(hr);
 354   }
 355 
 356   return new_obj;
 357 }
 358 
 359 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 360   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 361   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 362 }
 363 
 364 // If could fit into free regions w/o expansion, try.
 365 // Otherwise, if can expand, do so.
 366 // Otherwise, if using ex regions might help, try with ex given back.
 367 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 368   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 369 
 370   _verifier->verify_region_sets_optional();
 371 
 372   uint first = G1_NO_HRM_INDEX;
 373   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 374 
 375   if (obj_regions == 1) {
 376     // Only one region to allocate, try to use a fast path by directly allocating
 377     // from the free lists. Do not try to expand here, we will potentially do that
 378     // later.
 379     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 380     if (hr != NULL) {
 381       first = hr->hrm_index();
 382     }
 383   } else {
 384     // We can't allocate humongous regions spanning more than one region while
 385     // cleanupComplete() is running, since some of the regions we find to be
 386     // empty might not yet be added to the free list. It is not straightforward
 387     // to know in which list they are on so that we can remove them. We only
 388     // need to do this if we need to allocate more than one region to satisfy the
 389     // current humongous allocation request. If we are only allocating one region
 390     // we use the one-region region allocation code (see above), that already
 391     // potentially waits for regions from the secondary free list.
 392     wait_while_free_regions_coming();
 393     append_secondary_free_list_if_not_empty_with_lock();
 394 
 395     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 396     // are lucky enough to find some.
 397     first = _hrm.find_contiguous_only_empty(obj_regions);
 398     if (first != G1_NO_HRM_INDEX) {
 399       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 400     }
 401   }
 402 
 403   if (first == G1_NO_HRM_INDEX) {
 404     // Policy: We could not find enough regions for the humongous object in the
 405     // free list. Look through the heap to find a mix of free and uncommitted regions.
 406     // If so, try expansion.
 407     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 408     if (first != G1_NO_HRM_INDEX) {
 409       // We found something. Make sure these regions are committed, i.e. expand
 410       // the heap. Alternatively we could do a defragmentation GC.
 411       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 412                                     word_size * HeapWordSize);
 413 
 414       _hrm.expand_at(first, obj_regions, workers());
 415       g1_policy()->record_new_heap_size(num_regions());
 416 
 417 #ifdef ASSERT
 418       for (uint i = first; i < first + obj_regions; ++i) {
 419         HeapRegion* hr = region_at(i);
 420         assert(hr->is_free(), "sanity");
 421         assert(hr->is_empty(), "sanity");
 422         assert(is_on_master_free_list(hr), "sanity");
 423       }
 424 #endif
 425       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 426     } else {
 427       // Policy: Potentially trigger a defragmentation GC.
 428     }
 429   }
 430 
 431   HeapWord* result = NULL;
 432   if (first != G1_NO_HRM_INDEX) {
 433     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 434                                                        word_size, context);
 435     assert(result != NULL, "it should always return a valid result");
 436 
 437     // A successful humongous object allocation changes the used space
 438     // information of the old generation so we need to recalculate the
 439     // sizes and update the jstat counters here.
 440     g1mm()->update_sizes();
 441   }
 442 
 443   _verifier->verify_region_sets_optional();
 444 
 445   return result;
 446 }
 447 
 448 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 449   assert_heap_not_locked_and_not_at_safepoint();
 450   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 451 
 452   uint dummy_gc_count_before;
 453   uint dummy_gclocker_retry_count = 0;
 454   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 455 }
 456 
 457 HeapWord*
 458 G1CollectedHeap::mem_allocate(size_t word_size,
 459                               bool*  gc_overhead_limit_was_exceeded) {
 460   assert_heap_not_locked_and_not_at_safepoint();
 461 
 462   // Loop until the allocation is satisfied, or unsatisfied after GC.
 463   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 464     uint gc_count_before;
 465 
 466     HeapWord* result = NULL;
 467     if (!is_humongous(word_size)) {
 468       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 469     } else {
 470       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 471     }
 472     if (result != NULL) {
 473       return result;
 474     }
 475 
 476     // Create the garbage collection operation...
 477     VM_G1CollectForAllocation op(gc_count_before, word_size);
 478     op.set_allocation_context(AllocationContext::current());
 479 
 480     // ...and get the VM thread to execute it.
 481     VMThread::execute(&op);
 482 
 483     if (op.prologue_succeeded() && op.pause_succeeded()) {
 484       // If the operation was successful we'll return the result even
 485       // if it is NULL. If the allocation attempt failed immediately
 486       // after a Full GC, it's unlikely we'll be able to allocate now.
 487       HeapWord* result = op.result();
 488       if (result != NULL && !is_humongous(word_size)) {
 489         // Allocations that take place on VM operations do not do any
 490         // card dirtying and we have to do it here. We only have to do
 491         // this for non-humongous allocations, though.
 492         dirty_young_block(result, word_size);
 493       }
 494       return result;
 495     } else {
 496       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 497         return NULL;
 498       }
 499       assert(op.result() == NULL,
 500              "the result should be NULL if the VM op did not succeed");
 501     }
 502 
 503     // Give a warning if we seem to be looping forever.
 504     if ((QueuedAllocationWarningCount > 0) &&
 505         (try_count % QueuedAllocationWarningCount == 0)) {
 506       log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
 507     }
 508   }
 509 
 510   ShouldNotReachHere();
 511   return NULL;
 512 }
 513 
 514 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 515                                                    AllocationContext_t context,
 516                                                    uint* gc_count_before_ret,
 517                                                    uint* gclocker_retry_count_ret) {
 518   // Make sure you read the note in attempt_allocation_humongous().
 519 
 520   assert_heap_not_locked_and_not_at_safepoint();
 521   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 522          "be called for humongous allocation requests");
 523 
 524   // We should only get here after the first-level allocation attempt
 525   // (attempt_allocation()) failed to allocate.
 526 
 527   // We will loop until a) we manage to successfully perform the
 528   // allocation or b) we successfully schedule a collection which
 529   // fails to perform the allocation. b) is the only case when we'll
 530   // return NULL.
 531   HeapWord* result = NULL;
 532   for (int try_count = 1; /* we'll return */; try_count += 1) {
 533     bool should_try_gc;
 534     uint gc_count_before;
 535 
 536     {
 537       MutexLockerEx x(Heap_lock);
 538       result = _allocator->attempt_allocation_locked(word_size, context);
 539       if (result != NULL) {
 540         return result;
 541       }
 542 
 543       if (GCLocker::is_active_and_needs_gc()) {
 544         if (g1_policy()->can_expand_young_list()) {
 545           // No need for an ergo verbose message here,
 546           // can_expand_young_list() does this when it returns true.
 547           result = _allocator->attempt_allocation_force(word_size, context);
 548           if (result != NULL) {
 549             return result;
 550           }
 551         }
 552         should_try_gc = false;
 553       } else {
 554         // The GCLocker may not be active but the GCLocker initiated
 555         // GC may not yet have been performed (GCLocker::needs_gc()
 556         // returns true). In this case we do not try this GC and
 557         // wait until the GCLocker initiated GC is performed, and
 558         // then retry the allocation.
 559         if (GCLocker::needs_gc()) {
 560           should_try_gc = false;
 561         } else {
 562           // Read the GC count while still holding the Heap_lock.
 563           gc_count_before = total_collections();
 564           should_try_gc = true;
 565         }
 566       }
 567     }
 568 
 569     if (should_try_gc) {
 570       bool succeeded;
 571       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 572                                    GCCause::_g1_inc_collection_pause);
 573       if (result != NULL) {
 574         assert(succeeded, "only way to get back a non-NULL result");
 575         return result;
 576       }
 577 
 578       if (succeeded) {
 579         // If we get here we successfully scheduled a collection which
 580         // failed to allocate. No point in trying to allocate
 581         // further. We'll just return NULL.
 582         MutexLockerEx x(Heap_lock);
 583         *gc_count_before_ret = total_collections();
 584         return NULL;
 585       }
 586     } else {
 587       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 588         MutexLockerEx x(Heap_lock);
 589         *gc_count_before_ret = total_collections();
 590         return NULL;
 591       }
 592       // The GCLocker is either active or the GCLocker initiated
 593       // GC has not yet been performed. Stall until it is and
 594       // then retry the allocation.
 595       GCLocker::stall_until_clear();
 596       (*gclocker_retry_count_ret) += 1;
 597     }
 598 
 599     // We can reach here if we were unsuccessful in scheduling a
 600     // collection (because another thread beat us to it) or if we were
 601     // stalled due to the GC locker. In either can we should retry the
 602     // allocation attempt in case another thread successfully
 603     // performed a collection and reclaimed enough space. We do the
 604     // first attempt (without holding the Heap_lock) here and the
 605     // follow-on attempt will be at the start of the next loop
 606     // iteration (after taking the Heap_lock).
 607     result = _allocator->attempt_allocation(word_size, context);
 608     if (result != NULL) {
 609       return result;
 610     }
 611 
 612     // Give a warning if we seem to be looping forever.
 613     if ((QueuedAllocationWarningCount > 0) &&
 614         (try_count % QueuedAllocationWarningCount == 0)) {
 615       log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
 616                       "retries %d times", try_count);
 617     }
 618   }
 619 
 620   ShouldNotReachHere();
 621   return NULL;
 622 }
 623 
 624 void G1CollectedHeap::begin_archive_alloc_range() {
 625   assert_at_safepoint(true /* should_be_vm_thread */);
 626   if (_archive_allocator == NULL) {
 627     _archive_allocator = G1ArchiveAllocator::create_allocator(this);
 628   }
 629 }
 630 
 631 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 632   // Allocations in archive regions cannot be of a size that would be considered
 633   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 634   // may be different at archive-restore time.
 635   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 636 }
 637 
 638 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 639   assert_at_safepoint(true /* should_be_vm_thread */);
 640   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 641   if (is_archive_alloc_too_large(word_size)) {
 642     return NULL;
 643   }
 644   return _archive_allocator->archive_mem_allocate(word_size);
 645 }
 646 
 647 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 648                                               size_t end_alignment_in_bytes) {
 649   assert_at_safepoint(true /* should_be_vm_thread */);
 650   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 651 
 652   // Call complete_archive to do the real work, filling in the MemRegion
 653   // array with the archive regions.
 654   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 655   delete _archive_allocator;
 656   _archive_allocator = NULL;
 657 }
 658 
 659 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 660   assert(ranges != NULL, "MemRegion array NULL");
 661   assert(count != 0, "No MemRegions provided");
 662   MemRegion reserved = _hrm.reserved();
 663   for (size_t i = 0; i < count; i++) {
 664     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 665       return false;
 666     }
 667   }
 668   return true;
 669 }
 670 
 671 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
 672   assert(!is_init_completed(), "Expect to be called at JVM init time");
 673   assert(ranges != NULL, "MemRegion array NULL");
 674   assert(count != 0, "No MemRegions provided");
 675   MutexLockerEx x(Heap_lock);
 676 
 677   MemRegion reserved = _hrm.reserved();
 678   HeapWord* prev_last_addr = NULL;
 679   HeapRegion* prev_last_region = NULL;
 680 
 681   // Temporarily disable pretouching of heap pages. This interface is used
 682   // when mmap'ing archived heap data in, so pre-touching is wasted.
 683   FlagSetting fs(AlwaysPreTouch, false);
 684 
 685   // Enable archive object checking used by G1MarkSweep. We have to let it know
 686   // about each archive range, so that objects in those ranges aren't marked.
 687   G1ArchiveAllocator::enable_archive_object_check();
 688 
 689   // For each specified MemRegion range, allocate the corresponding G1
 690   // regions and mark them as archive regions. We expect the ranges in
 691   // ascending starting address order, without overlap.
 692   for (size_t i = 0; i < count; i++) {
 693     MemRegion curr_range = ranges[i];
 694     HeapWord* start_address = curr_range.start();
 695     size_t word_size = curr_range.word_size();
 696     HeapWord* last_address = curr_range.last();
 697     size_t commits = 0;
 698 
 699     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 700               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 701               p2i(start_address), p2i(last_address));
 702     guarantee(start_address > prev_last_addr,
 703               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 704               p2i(start_address), p2i(prev_last_addr));
 705     prev_last_addr = last_address;
 706 
 707     // Check for ranges that start in the same G1 region in which the previous
 708     // range ended, and adjust the start address so we don't try to allocate
 709     // the same region again. If the current range is entirely within that
 710     // region, skip it, just adjusting the recorded top.
 711     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 712     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 713       start_address = start_region->end();
 714       if (start_address > last_address) {
 715         increase_used(word_size * HeapWordSize);
 716         start_region->set_top(last_address + 1);
 717         continue;
 718       }
 719       start_region->set_top(start_address);
 720       curr_range = MemRegion(start_address, last_address + 1);
 721       start_region = _hrm.addr_to_region(start_address);
 722     }
 723 
 724     // Perform the actual region allocation, exiting if it fails.
 725     // Then note how much new space we have allocated.
 726     if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
 727       return false;
 728     }
 729     increase_used(word_size * HeapWordSize);
 730     if (commits != 0) {
 731       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 732                                 HeapRegion::GrainWords * HeapWordSize * commits);
 733 
 734     }
 735 
 736     // Mark each G1 region touched by the range as archive, add it to the old set,
 737     // and set the allocation context and top.
 738     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 739     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 740     prev_last_region = last_region;
 741 
 742     while (curr_region != NULL) {
 743       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 744              "Region already in use (index %u)", curr_region->hrm_index());
 745       curr_region->set_allocation_context(AllocationContext::system());
 746       curr_region->set_archive();
 747       _hr_printer.alloc(curr_region);
 748       _old_set.add(curr_region);
 749       if (curr_region != last_region) {
 750         curr_region->set_top(curr_region->end());
 751         curr_region = _hrm.next_region_in_heap(curr_region);
 752       } else {
 753         curr_region->set_top(last_address + 1);
 754         curr_region = NULL;
 755       }
 756     }
 757 
 758     // Notify mark-sweep of the archive range.
 759     G1ArchiveAllocator::set_range_archive(curr_range, true);
 760   }
 761   return true;
 762 }
 763 
 764 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 765   assert(!is_init_completed(), "Expect to be called at JVM init time");
 766   assert(ranges != NULL, "MemRegion array NULL");
 767   assert(count != 0, "No MemRegions provided");
 768   MemRegion reserved = _hrm.reserved();
 769   HeapWord *prev_last_addr = NULL;
 770   HeapRegion* prev_last_region = NULL;
 771 
 772   // For each MemRegion, create filler objects, if needed, in the G1 regions
 773   // that contain the address range. The address range actually within the
 774   // MemRegion will not be modified. That is assumed to have been initialized
 775   // elsewhere, probably via an mmap of archived heap data.
 776   MutexLockerEx x(Heap_lock);
 777   for (size_t i = 0; i < count; i++) {
 778     HeapWord* start_address = ranges[i].start();
 779     HeapWord* last_address = ranges[i].last();
 780 
 781     assert(reserved.contains(start_address) && reserved.contains(last_address),
 782            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 783            p2i(start_address), p2i(last_address));
 784     assert(start_address > prev_last_addr,
 785            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 786            p2i(start_address), p2i(prev_last_addr));
 787 
 788     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 789     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 790     HeapWord* bottom_address = start_region->bottom();
 791 
 792     // Check for a range beginning in the same region in which the
 793     // previous one ended.
 794     if (start_region == prev_last_region) {
 795       bottom_address = prev_last_addr + 1;
 796     }
 797 
 798     // Verify that the regions were all marked as archive regions by
 799     // alloc_archive_regions.
 800     HeapRegion* curr_region = start_region;
 801     while (curr_region != NULL) {
 802       guarantee(curr_region->is_archive(),
 803                 "Expected archive region at index %u", curr_region->hrm_index());
 804       if (curr_region != last_region) {
 805         curr_region = _hrm.next_region_in_heap(curr_region);
 806       } else {
 807         curr_region = NULL;
 808       }
 809     }
 810 
 811     prev_last_addr = last_address;
 812     prev_last_region = last_region;
 813 
 814     // Fill the memory below the allocated range with dummy object(s),
 815     // if the region bottom does not match the range start, or if the previous
 816     // range ended within the same G1 region, and there is a gap.
 817     if (start_address != bottom_address) {
 818       size_t fill_size = pointer_delta(start_address, bottom_address);
 819       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 820       increase_used(fill_size * HeapWordSize);
 821     }
 822   }
 823 }
 824 
 825 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
 826                                                      uint* gc_count_before_ret,
 827                                                      uint* gclocker_retry_count_ret) {
 828   assert_heap_not_locked_and_not_at_safepoint();
 829   assert(!is_humongous(word_size), "attempt_allocation() should not "
 830          "be called for humongous allocation requests");
 831 
 832   AllocationContext_t context = AllocationContext::current();
 833   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 834 
 835   if (result == NULL) {
 836     result = attempt_allocation_slow(word_size,
 837                                      context,
 838                                      gc_count_before_ret,
 839                                      gclocker_retry_count_ret);
 840   }
 841   assert_heap_not_locked();
 842   if (result != NULL) {
 843     dirty_young_block(result, word_size);
 844   }
 845   return result;
 846 }
 847 
 848 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 849   assert(!is_init_completed(), "Expect to be called at JVM init time");
 850   assert(ranges != NULL, "MemRegion array NULL");
 851   assert(count != 0, "No MemRegions provided");
 852   MemRegion reserved = _hrm.reserved();
 853   HeapWord* prev_last_addr = NULL;
 854   HeapRegion* prev_last_region = NULL;
 855   size_t size_used = 0;
 856   size_t uncommitted_regions = 0;
 857 
 858   // For each Memregion, free the G1 regions that constitute it, and
 859   // notify mark-sweep that the range is no longer to be considered 'archive.'
 860   MutexLockerEx x(Heap_lock);
 861   for (size_t i = 0; i < count; i++) {
 862     HeapWord* start_address = ranges[i].start();
 863     HeapWord* last_address = ranges[i].last();
 864 
 865     assert(reserved.contains(start_address) && reserved.contains(last_address),
 866            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 867            p2i(start_address), p2i(last_address));
 868     assert(start_address > prev_last_addr,
 869            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 870            p2i(start_address), p2i(prev_last_addr));
 871     size_used += ranges[i].byte_size();
 872     prev_last_addr = last_address;
 873 
 874     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 875     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 876 
 877     // Check for ranges that start in the same G1 region in which the previous
 878     // range ended, and adjust the start address so we don't try to free
 879     // the same region again. If the current range is entirely within that
 880     // region, skip it.
 881     if (start_region == prev_last_region) {
 882       start_address = start_region->end();
 883       if (start_address > last_address) {
 884         continue;
 885       }
 886       start_region = _hrm.addr_to_region(start_address);
 887     }
 888     prev_last_region = last_region;
 889 
 890     // After verifying that each region was marked as an archive region by
 891     // alloc_archive_regions, set it free and empty and uncommit it.
 892     HeapRegion* curr_region = start_region;
 893     while (curr_region != NULL) {
 894       guarantee(curr_region->is_archive(),
 895                 "Expected archive region at index %u", curr_region->hrm_index());
 896       uint curr_index = curr_region->hrm_index();
 897       _old_set.remove(curr_region);
 898       curr_region->set_free();
 899       curr_region->set_top(curr_region->bottom());
 900       if (curr_region != last_region) {
 901         curr_region = _hrm.next_region_in_heap(curr_region);
 902       } else {
 903         curr_region = NULL;
 904       }
 905       _hrm.shrink_at(curr_index, 1);
 906       uncommitted_regions++;
 907     }
 908 
 909     // Notify mark-sweep that this is no longer an archive range.
 910     G1ArchiveAllocator::set_range_archive(ranges[i], false);
 911   }
 912 
 913   if (uncommitted_regions != 0) {
 914     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 915                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 916   }
 917   decrease_used(size_used);
 918 }
 919 
 920 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 921                                                         uint* gc_count_before_ret,
 922                                                         uint* gclocker_retry_count_ret) {
 923   // The structure of this method has a lot of similarities to
 924   // attempt_allocation_slow(). The reason these two were not merged
 925   // into a single one is that such a method would require several "if
 926   // allocation is not humongous do this, otherwise do that"
 927   // conditional paths which would obscure its flow. In fact, an early
 928   // version of this code did use a unified method which was harder to
 929   // follow and, as a result, it had subtle bugs that were hard to
 930   // track down. So keeping these two methods separate allows each to
 931   // be more readable. It will be good to keep these two in sync as
 932   // much as possible.
 933 
 934   assert_heap_not_locked_and_not_at_safepoint();
 935   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 936          "should only be called for humongous allocations");
 937 
 938   // Humongous objects can exhaust the heap quickly, so we should check if we
 939   // need to start a marking cycle at each humongous object allocation. We do
 940   // the check before we do the actual allocation. The reason for doing it
 941   // before the allocation is that we avoid having to keep track of the newly
 942   // allocated memory while we do a GC.
 943   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 944                                            word_size)) {
 945     collect(GCCause::_g1_humongous_allocation);
 946   }
 947 
 948   // We will loop until a) we manage to successfully perform the
 949   // allocation or b) we successfully schedule a collection which
 950   // fails to perform the allocation. b) is the only case when we'll
 951   // return NULL.
 952   HeapWord* result = NULL;
 953   for (int try_count = 1; /* we'll return */; try_count += 1) {
 954     bool should_try_gc;
 955     uint gc_count_before;
 956 
 957     {
 958       MutexLockerEx x(Heap_lock);
 959 
 960       // Given that humongous objects are not allocated in young
 961       // regions, we'll first try to do the allocation without doing a
 962       // collection hoping that there's enough space in the heap.
 963       result = humongous_obj_allocate(word_size, AllocationContext::current());
 964       if (result != NULL) {
 965         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 966         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 967         return result;
 968       }
 969 
 970       if (GCLocker::is_active_and_needs_gc()) {
 971         should_try_gc = false;
 972       } else {
 973          // The GCLocker may not be active but the GCLocker initiated
 974         // GC may not yet have been performed (GCLocker::needs_gc()
 975         // returns true). In this case we do not try this GC and
 976         // wait until the GCLocker initiated GC is performed, and
 977         // then retry the allocation.
 978         if (GCLocker::needs_gc()) {
 979           should_try_gc = false;
 980         } else {
 981           // Read the GC count while still holding the Heap_lock.
 982           gc_count_before = total_collections();
 983           should_try_gc = true;
 984         }
 985       }
 986     }
 987 
 988     if (should_try_gc) {
 989       // If we failed to allocate the humongous object, we should try to
 990       // do a collection pause (if we're allowed) in case it reclaims
 991       // enough space for the allocation to succeed after the pause.
 992 
 993       bool succeeded;
 994       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 995                                    GCCause::_g1_humongous_allocation);
 996       if (result != NULL) {
 997         assert(succeeded, "only way to get back a non-NULL result");
 998         return result;
 999       }
1000 
1001       if (succeeded) {
1002         // If we get here we successfully scheduled a collection which
1003         // failed to allocate. No point in trying to allocate
1004         // further. We'll just return NULL.
1005         MutexLockerEx x(Heap_lock);
1006         *gc_count_before_ret = total_collections();
1007         return NULL;
1008       }
1009     } else {
1010       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1011         MutexLockerEx x(Heap_lock);
1012         *gc_count_before_ret = total_collections();
1013         return NULL;
1014       }
1015       // The GCLocker is either active or the GCLocker initiated
1016       // GC has not yet been performed. Stall until it is and
1017       // then retry the allocation.
1018       GCLocker::stall_until_clear();
1019       (*gclocker_retry_count_ret) += 1;
1020     }
1021 
1022     // We can reach here if we were unsuccessful in scheduling a
1023     // collection (because another thread beat us to it) or if we were
1024     // stalled due to the GC locker. In either can we should retry the
1025     // allocation attempt in case another thread successfully
1026     // performed a collection and reclaimed enough space.  Give a
1027     // warning if we seem to be looping forever.
1028 
1029     if ((QueuedAllocationWarningCount > 0) &&
1030         (try_count % QueuedAllocationWarningCount == 0)) {
1031       log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1032                       "retries %d times", try_count);
1033     }
1034   }
1035 
1036   ShouldNotReachHere();
1037   return NULL;
1038 }
1039 
1040 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1041                                                            AllocationContext_t context,
1042                                                            bool expect_null_mutator_alloc_region) {
1043   assert_at_safepoint(true /* should_be_vm_thread */);
1044   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1045          "the current alloc region was unexpectedly found to be non-NULL");
1046 
1047   if (!is_humongous(word_size)) {
1048     return _allocator->attempt_allocation_locked(word_size, context);
1049   } else {
1050     HeapWord* result = humongous_obj_allocate(word_size, context);
1051     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1052       collector_state()->set_initiate_conc_mark_if_possible(true);
1053     }
1054     return result;
1055   }
1056 
1057   ShouldNotReachHere();
1058 }
1059 
1060 class PostCompactionPrinterClosure: public HeapRegionClosure {
1061 private:
1062   G1HRPrinter* _hr_printer;
1063 public:
1064   bool doHeapRegion(HeapRegion* hr) {
1065     assert(!hr->is_young(), "not expecting to find young regions");
1066     _hr_printer->post_compaction(hr);
1067     return false;
1068   }
1069 
1070   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1071     : _hr_printer(hr_printer) { }
1072 };
1073 
1074 void G1CollectedHeap::print_hrm_post_compaction() {
1075   if (_hr_printer.is_active()) {
1076     PostCompactionPrinterClosure cl(hr_printer());
1077     heap_region_iterate(&cl);
1078   }
1079 
1080 }
1081 
1082 void G1CollectedHeap::abort_concurrent_cycle() {
1083   // Note: When we have a more flexible GC logging framework that
1084   // allows us to add optional attributes to a GC log record we
1085   // could consider timing and reporting how long we wait in the
1086   // following two methods.
1087   wait_while_free_regions_coming();
1088   // If we start the compaction before the CM threads finish
1089   // scanning the root regions we might trip them over as we'll
1090   // be moving objects / updating references. So let's wait until
1091   // they are done. By telling them to abort, they should complete
1092   // early.
1093   _cm->root_regions()->abort();
1094   _cm->root_regions()->wait_until_scan_finished();
1095   append_secondary_free_list_if_not_empty_with_lock();
1096 
1097   // Disable discovery and empty the discovered lists
1098   // for the CM ref processor.
1099   ref_processor_cm()->disable_discovery();
1100   ref_processor_cm()->abandon_partial_discovery();
1101   ref_processor_cm()->verify_no_references_recorded();
1102 
1103   // Abandon current iterations of concurrent marking and concurrent
1104   // refinement, if any are in progress.
1105   concurrent_mark()->abort();
1106 }
1107 
1108 void G1CollectedHeap::prepare_heap_for_full_collection() {
1109   // Make sure we'll choose a new allocation region afterwards.
1110   _allocator->release_mutator_alloc_region();
1111   _allocator->abandon_gc_alloc_regions();
1112   g1_rem_set()->cleanupHRRS();
1113 
1114   // We may have added regions to the current incremental collection
1115   // set between the last GC or pause and now. We need to clear the
1116   // incremental collection set and then start rebuilding it afresh
1117   // after this full GC.
1118   abandon_collection_set(collection_set());
1119 
1120   tear_down_region_sets(false /* free_list_only */);
1121   collector_state()->set_gcs_are_young(true);
1122 }
1123 
1124 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1125   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1126   assert(used() == recalculate_used(), "Should be equal");
1127   _verifier->verify_region_sets_optional();
1128   _verifier->verify_before_gc();
1129   _verifier->check_bitmaps("Full GC Start");
1130 }
1131 
1132 void G1CollectedHeap::prepare_heap_for_mutators() {
1133   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1134   ClassLoaderDataGraph::purge();
1135   MetaspaceAux::verify_metrics();
1136 
1137   // Prepare heap for normal collections.
1138   assert(num_free_regions() == 0, "we should not have added any free regions");
1139   rebuild_region_sets(false /* free_list_only */);
1140   abort_refinement();
1141   resize_if_necessary_after_full_collection();
1142 
1143   // Rebuild the strong code root lists for each region
1144   rebuild_strong_code_roots();
1145 
1146   // Start a new incremental collection set for the next pause
1147   start_new_collection_set();
1148 
1149   _allocator->init_mutator_alloc_region();
1150 
1151   // Post collection state updates.
1152   MetaspaceGC::compute_new_size();
1153 }
1154 
1155 void G1CollectedHeap::abort_refinement() {
1156   if (_hot_card_cache->use_cache()) {
1157     _hot_card_cache->reset_card_counts();
1158     _hot_card_cache->reset_hot_cache();
1159   }
1160 
1161   // Discard all remembered set updates.
1162   JavaThread::dirty_card_queue_set().abandon_logs();
1163   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1164 }
1165 
1166 void G1CollectedHeap::verify_after_full_collection() {
1167   check_gc_time_stamps();
1168   _hrm.verify_optional();
1169   _verifier->verify_region_sets_optional();
1170   _verifier->verify_after_gc();
1171   // Clear the previous marking bitmap, if needed for bitmap verification.
1172   // Note we cannot do this when we clear the next marking bitmap in
1173   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1174   // objects marked during a full GC against the previous bitmap.
1175   // But we need to clear it before calling check_bitmaps below since
1176   // the full GC has compacted objects and updated TAMS but not updated
1177   // the prev bitmap.
1178   if (G1VerifyBitmaps) {
1179     GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1180     _cm->clear_prev_bitmap(workers());
1181   }
1182   _verifier->check_bitmaps("Full GC End");
1183 
1184   // At this point there should be no regions in the
1185   // entire heap tagged as young.
1186   assert(check_young_list_empty(), "young list should be empty at this point");
1187 
1188   // Note: since we've just done a full GC, concurrent
1189   // marking is no longer active. Therefore we need not
1190   // re-enable reference discovery for the CM ref processor.
1191   // That will be done at the start of the next marking cycle.
1192   // We also know that the STW processor should no longer
1193   // discover any new references.
1194   assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1195   assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1196   ref_processor_stw()->verify_no_references_recorded();
1197   ref_processor_cm()->verify_no_references_recorded();
1198 }
1199 
1200 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1201   print_hrm_post_compaction();
1202   heap_transition->print();
1203   print_heap_after_gc();
1204   print_heap_regions();
1205 #ifdef TRACESPINNING
1206   ParallelTaskTerminator::print_termination_counts();
1207 #endif
1208 }
1209 
1210 void G1CollectedHeap::do_full_collection_inner(G1FullGCScope* scope) {
1211   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1212   g1_policy()->record_full_collection_start();
1213 
1214   print_heap_before_gc();
1215   print_heap_regions();
1216 
1217   abort_concurrent_cycle();
1218   verify_before_full_collection(scope->is_explicit_gc());
1219 
1220   gc_prologue(true);
1221   prepare_heap_for_full_collection();
1222 
1223   {
1224     G1FullCollector collector(scope, ref_processor_stw(), concurrent_mark()->nextMarkBitMap(), workers()->active_workers());
1225     // Prepare collection by putting reference processor
1226     // in a correct state.
1227     collector.prepare_collection();
1228 
1229     // Do the actual collection.
1230     collector.collect();
1231 
1232     collector.complete_collection();
1233   }
1234 
1235   prepare_heap_for_mutators();
1236 
1237   g1_policy()->record_full_collection_end();
1238   gc_epilogue(true);
1239 
1240   // Post collection verification.
1241   verify_after_full_collection();
1242 
1243   // Post collection logging.
1244   // We should do this after we potentially resize the heap so
1245   // that all the COMMIT / UNCOMMIT events are generated before
1246   // the compaction events.
1247   print_heap_after_full_collection(scope->heap_transition());
1248 }
1249 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1250                                          bool clear_all_soft_refs) {
1251   assert_at_safepoint(true /* should_be_vm_thread */);
1252 
1253   if (GCLocker::check_active_before_gc()) {
1254     // Full GC was not completed.
1255     return false;
1256   }
1257 
1258   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1259       collector_policy()->should_clear_all_soft_refs();
1260 
1261   G1FullGCScope scope(explicit_gc, do_clear_all_soft_refs);
1262   do_full_collection_inner(&scope);
1263 
1264   // Full collection was successfully completed.
1265   return true;
1266 }
1267 
1268 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1269   // Currently, there is no facility in the do_full_collection(bool) API to notify
1270   // the caller that the collection did not succeed (e.g., because it was locked
1271   // out by the GC locker). So, right now, we'll ignore the return value.
1272   bool dummy = do_full_collection(true,                /* explicit_gc */
1273                                   clear_all_soft_refs);
1274 }
1275 
1276 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1277   // Include bytes that will be pre-allocated to support collections, as "used".
1278   const size_t used_after_gc = used();
1279   const size_t capacity_after_gc = capacity();
1280   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1281 
1282   // This is enforced in arguments.cpp.
1283   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1284          "otherwise the code below doesn't make sense");
1285 
1286   // We don't have floating point command-line arguments
1287   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1288   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1289   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1290   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1291 
1292   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1293   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1294 
1295   // We have to be careful here as these two calculations can overflow
1296   // 32-bit size_t's.
1297   double used_after_gc_d = (double) used_after_gc;
1298   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1299   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1300 
1301   // Let's make sure that they are both under the max heap size, which
1302   // by default will make them fit into a size_t.
1303   double desired_capacity_upper_bound = (double) max_heap_size;
1304   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1305                                     desired_capacity_upper_bound);
1306   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1307                                     desired_capacity_upper_bound);
1308 
1309   // We can now safely turn them into size_t's.
1310   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1311   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1312 
1313   // This assert only makes sense here, before we adjust them
1314   // with respect to the min and max heap size.
1315   assert(minimum_desired_capacity <= maximum_desired_capacity,
1316          "minimum_desired_capacity = " SIZE_FORMAT ", "
1317          "maximum_desired_capacity = " SIZE_FORMAT,
1318          minimum_desired_capacity, maximum_desired_capacity);
1319 
1320   // Should not be greater than the heap max size. No need to adjust
1321   // it with respect to the heap min size as it's a lower bound (i.e.,
1322   // we'll try to make the capacity larger than it, not smaller).
1323   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1324   // Should not be less than the heap min size. No need to adjust it
1325   // with respect to the heap max size as it's an upper bound (i.e.,
1326   // we'll try to make the capacity smaller than it, not greater).
1327   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1328 
1329   if (capacity_after_gc < minimum_desired_capacity) {
1330     // Don't expand unless it's significant
1331     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1332 
1333     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1334                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1335                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1336 
1337     expand(expand_bytes, _workers);
1338 
1339     // No expansion, now see if we want to shrink
1340   } else if (capacity_after_gc > maximum_desired_capacity) {
1341     // Capacity too large, compute shrinking size
1342     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1343 
1344     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1345                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1346                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1347 
1348     shrink(shrink_bytes);
1349   }
1350 }
1351 
1352 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1353                                                             AllocationContext_t context,
1354                                                             bool do_gc,
1355                                                             bool clear_all_soft_refs,
1356                                                             bool expect_null_mutator_alloc_region,
1357                                                             bool* gc_succeeded) {
1358   *gc_succeeded = true;
1359   // Let's attempt the allocation first.
1360   HeapWord* result =
1361     attempt_allocation_at_safepoint(word_size,
1362                                     context,
1363                                     expect_null_mutator_alloc_region);
1364   if (result != NULL) {
1365     assert(*gc_succeeded, "sanity");
1366     return result;
1367   }
1368 
1369   // In a G1 heap, we're supposed to keep allocation from failing by
1370   // incremental pauses.  Therefore, at least for now, we'll favor
1371   // expansion over collection.  (This might change in the future if we can
1372   // do something smarter than full collection to satisfy a failed alloc.)
1373   result = expand_and_allocate(word_size, context);
1374   if (result != NULL) {
1375     assert(*gc_succeeded, "sanity");
1376     return result;
1377   }
1378 
1379   if (do_gc) {
1380     // Expansion didn't work, we'll try to do a Full GC.
1381     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1382                                        clear_all_soft_refs);
1383   }
1384 
1385   return NULL;
1386 }
1387 
1388 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1389                                                      AllocationContext_t context,
1390                                                      bool* succeeded) {
1391   assert_at_safepoint(true /* should_be_vm_thread */);
1392 
1393   // Attempts to allocate followed by Full GC.
1394   HeapWord* result =
1395     satisfy_failed_allocation_helper(word_size,
1396                                      context,
1397                                      true,  /* do_gc */
1398                                      false, /* clear_all_soft_refs */
1399                                      false, /* expect_null_mutator_alloc_region */
1400                                      succeeded);
1401 
1402   if (result != NULL || !*succeeded) {
1403     return result;
1404   }
1405 
1406   // Attempts to allocate followed by Full GC that will collect all soft references.
1407   result = satisfy_failed_allocation_helper(word_size,
1408                                             context,
1409                                             true, /* do_gc */
1410                                             true, /* clear_all_soft_refs */
1411                                             true, /* expect_null_mutator_alloc_region */
1412                                             succeeded);
1413 
1414   if (result != NULL || !*succeeded) {
1415     return result;
1416   }
1417 
1418   // Attempts to allocate, no GC
1419   result = satisfy_failed_allocation_helper(word_size,
1420                                             context,
1421                                             false, /* do_gc */
1422                                             false, /* clear_all_soft_refs */
1423                                             true,  /* expect_null_mutator_alloc_region */
1424                                             succeeded);
1425 
1426   if (result != NULL) {
1427     assert(*succeeded, "sanity");
1428     return result;
1429   }
1430 
1431   assert(!collector_policy()->should_clear_all_soft_refs(),
1432          "Flag should have been handled and cleared prior to this point");
1433 
1434   // What else?  We might try synchronous finalization later.  If the total
1435   // space available is large enough for the allocation, then a more
1436   // complete compaction phase than we've tried so far might be
1437   // appropriate.
1438   assert(*succeeded, "sanity");
1439   return NULL;
1440 }
1441 
1442 // Attempting to expand the heap sufficiently
1443 // to support an allocation of the given "word_size".  If
1444 // successful, perform the allocation and return the address of the
1445 // allocated block, or else "NULL".
1446 
1447 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1448   assert_at_safepoint(true /* should_be_vm_thread */);
1449 
1450   _verifier->verify_region_sets_optional();
1451 
1452   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1453   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1454                             word_size * HeapWordSize);
1455 
1456 
1457   if (expand(expand_bytes, _workers)) {
1458     _hrm.verify_optional();
1459     _verifier->verify_region_sets_optional();
1460     return attempt_allocation_at_safepoint(word_size,
1461                                            context,
1462                                            false /* expect_null_mutator_alloc_region */);
1463   }
1464   return NULL;
1465 }
1466 
1467 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1468   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1469   aligned_expand_bytes = align_up(aligned_expand_bytes,
1470                                        HeapRegion::GrainBytes);
1471 
1472   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1473                             expand_bytes, aligned_expand_bytes);
1474 
1475   if (is_maximal_no_gc()) {
1476     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1477     return false;
1478   }
1479 
1480   double expand_heap_start_time_sec = os::elapsedTime();
1481   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1482   assert(regions_to_expand > 0, "Must expand by at least one region");
1483 
1484   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1485   if (expand_time_ms != NULL) {
1486     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1487   }
1488 
1489   if (expanded_by > 0) {
1490     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1491     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1492     g1_policy()->record_new_heap_size(num_regions());
1493   } else {
1494     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1495 
1496     // The expansion of the virtual storage space was unsuccessful.
1497     // Let's see if it was because we ran out of swap.
1498     if (G1ExitOnExpansionFailure &&
1499         _hrm.available() >= regions_to_expand) {
1500       // We had head room...
1501       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1502     }
1503   }
1504   return regions_to_expand > 0;
1505 }
1506 
1507 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1508   size_t aligned_shrink_bytes =
1509     ReservedSpace::page_align_size_down(shrink_bytes);
1510   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1511                                          HeapRegion::GrainBytes);
1512   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1513 
1514   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1515   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1516 
1517 
1518   log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1519                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1520   if (num_regions_removed > 0) {
1521     g1_policy()->record_new_heap_size(num_regions());
1522   } else {
1523     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1524   }
1525 }
1526 
1527 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1528   _verifier->verify_region_sets_optional();
1529 
1530   // We should only reach here at the end of a Full GC which means we
1531   // should not not be holding to any GC alloc regions. The method
1532   // below will make sure of that and do any remaining clean up.
1533   _allocator->abandon_gc_alloc_regions();
1534 
1535   // Instead of tearing down / rebuilding the free lists here, we
1536   // could instead use the remove_all_pending() method on free_list to
1537   // remove only the ones that we need to remove.
1538   tear_down_region_sets(true /* free_list_only */);
1539   shrink_helper(shrink_bytes);
1540   rebuild_region_sets(true /* free_list_only */);
1541 
1542   _hrm.verify_optional();
1543   _verifier->verify_region_sets_optional();
1544 }
1545 
1546 // Public methods.
1547 
1548 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1549   CollectedHeap(),
1550   _collector_policy(collector_policy),
1551   _g1_policy(create_g1_policy()),
1552   _collection_set(this, _g1_policy),
1553   _dirty_card_queue_set(false),
1554   _is_alive_closure_cm(this),
1555   _is_alive_closure_stw(this),
1556   _ref_processor_cm(NULL),
1557   _ref_processor_stw(NULL),
1558   _bot(NULL),
1559   _hot_card_cache(NULL),
1560   _g1_rem_set(NULL),
1561   _cg1r(NULL),
1562   _g1mm(NULL),
1563   _preserved_marks_set(true /* in_c_heap */),
1564   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1565   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1566   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1567   _humongous_reclaim_candidates(),
1568   _has_humongous_reclaim_candidates(false),
1569   _archive_allocator(NULL),
1570   _free_regions_coming(false),
1571   _gc_time_stamp(0),
1572   _summary_bytes_used(0),
1573   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1574   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1575   _expand_heap_after_alloc_failure(true),
1576   _old_marking_cycles_started(0),
1577   _old_marking_cycles_completed(0),
1578   _in_cset_fast_test(),
1579   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1580   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1581 
1582   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1583                           /* are_GC_task_threads */true,
1584                           /* are_ConcurrentGC_threads */false);
1585   _workers->initialize_workers();
1586   _verifier = new G1HeapVerifier(this);
1587 
1588   _allocator = G1Allocator::create_allocator(this);
1589 
1590   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1591 
1592   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1593 
1594   // Override the default _filler_array_max_size so that no humongous filler
1595   // objects are created.
1596   _filler_array_max_size = _humongous_object_threshold_in_words;
1597 
1598   uint n_queues = ParallelGCThreads;
1599   _task_queues = new RefToScanQueueSet(n_queues);
1600 
1601   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1602 
1603   for (uint i = 0; i < n_queues; i++) {
1604     RefToScanQueue* q = new RefToScanQueue();
1605     q->initialize();
1606     _task_queues->register_queue(i, q);
1607     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1608   }
1609 
1610   // Initialize the G1EvacuationFailureALot counters and flags.
1611   NOT_PRODUCT(reset_evacuation_should_fail();)
1612 
1613   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1614 }
1615 
1616 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1617                                                                  size_t size,
1618                                                                  size_t translation_factor) {
1619   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1620   // Allocate a new reserved space, preferring to use large pages.
1621   ReservedSpace rs(size, preferred_page_size);
1622   G1RegionToSpaceMapper* result  =
1623     G1RegionToSpaceMapper::create_mapper(rs,
1624                                          size,
1625                                          rs.alignment(),
1626                                          HeapRegion::GrainBytes,
1627                                          translation_factor,
1628                                          mtGC);
1629 
1630   os::trace_page_sizes_for_requested_size(description,
1631                                           size,
1632                                           preferred_page_size,
1633                                           rs.alignment(),
1634                                           rs.base(),
1635                                           rs.size());
1636 
1637   return result;
1638 }
1639 
1640 jint G1CollectedHeap::initialize_concurrent_refinement() {
1641   jint ecode = JNI_OK;
1642   _cg1r = ConcurrentG1Refine::create(&ecode);
1643   return ecode;
1644 }
1645 
1646 jint G1CollectedHeap::initialize() {
1647   CollectedHeap::pre_initialize();
1648   os::enable_vtime();
1649 
1650   // Necessary to satisfy locking discipline assertions.
1651 
1652   MutexLocker x(Heap_lock);
1653 
1654   // While there are no constraints in the GC code that HeapWordSize
1655   // be any particular value, there are multiple other areas in the
1656   // system which believe this to be true (e.g. oop->object_size in some
1657   // cases incorrectly returns the size in wordSize units rather than
1658   // HeapWordSize).
1659   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1660 
1661   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1662   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1663   size_t heap_alignment = collector_policy()->heap_alignment();
1664 
1665   // Ensure that the sizes are properly aligned.
1666   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1667   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1668   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1669 
1670   // Reserve the maximum.
1671 
1672   // When compressed oops are enabled, the preferred heap base
1673   // is calculated by subtracting the requested size from the
1674   // 32Gb boundary and using the result as the base address for
1675   // heap reservation. If the requested size is not aligned to
1676   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1677   // into the ReservedHeapSpace constructor) then the actual
1678   // base of the reserved heap may end up differing from the
1679   // address that was requested (i.e. the preferred heap base).
1680   // If this happens then we could end up using a non-optimal
1681   // compressed oops mode.
1682 
1683   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1684                                                  heap_alignment);
1685 
1686   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1687 
1688   // Create the barrier set for the entire reserved region.
1689   G1SATBCardTableLoggingModRefBS* bs
1690     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1691   bs->initialize();
1692   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1693   set_barrier_set(bs);
1694 
1695   // Create the hot card cache.
1696   _hot_card_cache = new G1HotCardCache(this);
1697 
1698   // Carve out the G1 part of the heap.
1699   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1700   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1701   G1RegionToSpaceMapper* heap_storage =
1702     G1RegionToSpaceMapper::create_mapper(g1_rs,
1703                                          g1_rs.size(),
1704                                          page_size,
1705                                          HeapRegion::GrainBytes,
1706                                          1,
1707                                          mtJavaHeap);
1708   os::trace_page_sizes("Heap",
1709                        collector_policy()->min_heap_byte_size(),
1710                        max_byte_size,
1711                        page_size,
1712                        heap_rs.base(),
1713                        heap_rs.size());
1714   heap_storage->set_mapping_changed_listener(&_listener);
1715 
1716   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1717   G1RegionToSpaceMapper* bot_storage =
1718     create_aux_memory_mapper("Block Offset Table",
1719                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1720                              G1BlockOffsetTable::heap_map_factor());
1721 
1722   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1723   G1RegionToSpaceMapper* cardtable_storage =
1724     create_aux_memory_mapper("Card Table",
1725                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1726                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1727 
1728   G1RegionToSpaceMapper* card_counts_storage =
1729     create_aux_memory_mapper("Card Counts Table",
1730                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1731                              G1CardCounts::heap_map_factor());
1732 
1733   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1734   G1RegionToSpaceMapper* prev_bitmap_storage =
1735     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1736   G1RegionToSpaceMapper* next_bitmap_storage =
1737     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1738 
1739   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1740   g1_barrier_set()->initialize(cardtable_storage);
1741   // Do later initialization work for concurrent refinement.
1742   _hot_card_cache->initialize(card_counts_storage);
1743 
1744   // 6843694 - ensure that the maximum region index can fit
1745   // in the remembered set structures.
1746   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1747   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1748 
1749   // Also create a G1 rem set.
1750   _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1751   _g1_rem_set->initialize(max_capacity(), max_regions());
1752 
1753   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1754   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1755   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1756             "too many cards per region");
1757 
1758   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1759 
1760   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1761 
1762   {
1763     HeapWord* start = _hrm.reserved().start();
1764     HeapWord* end = _hrm.reserved().end();
1765     size_t granularity = HeapRegion::GrainBytes;
1766 
1767     _in_cset_fast_test.initialize(start, end, granularity);
1768     _humongous_reclaim_candidates.initialize(start, end, granularity);
1769   }
1770 
1771   // Create the G1ConcurrentMark data structure and thread.
1772   // (Must do this late, so that "max_regions" is defined.)
1773   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1774   if (_cm == NULL || !_cm->completed_initialization()) {
1775     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1776     return JNI_ENOMEM;
1777   }
1778   _cmThread = _cm->cmThread();
1779 
1780   // Now expand into the initial heap size.
1781   if (!expand(init_byte_size, _workers)) {
1782     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1783     return JNI_ENOMEM;
1784   }
1785 
1786   // Perform any initialization actions delegated to the policy.
1787   g1_policy()->init(this, &_collection_set);
1788 
1789   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1790                                                SATB_Q_FL_lock,
1791                                                G1SATBProcessCompletedThreshold,
1792                                                Shared_SATB_Q_lock);
1793 
1794   jint ecode = initialize_concurrent_refinement();
1795   if (ecode != JNI_OK) {
1796     return ecode;
1797   }
1798   
1799   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1800                                                 DirtyCardQ_FL_lock,
1801                                                 (int)concurrent_g1_refine()->yellow_zone(),
1802                                                 (int)concurrent_g1_refine()->red_zone(),
1803                                                 Shared_DirtyCardQ_lock,
1804                                                 NULL,  // fl_owner
1805                                                 true); // init_free_ids
1806 
1807   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1808                                     DirtyCardQ_FL_lock,
1809                                     -1, // never trigger processing
1810                                     -1, // no limit on length
1811                                     Shared_DirtyCardQ_lock,
1812                                     &JavaThread::dirty_card_queue_set());
1813 
1814   // Here we allocate the dummy HeapRegion that is required by the
1815   // G1AllocRegion class.
1816   HeapRegion* dummy_region = _hrm.get_dummy_region();
1817 
1818   // We'll re-use the same region whether the alloc region will
1819   // require BOT updates or not and, if it doesn't, then a non-young
1820   // region will complain that it cannot support allocations without
1821   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1822   dummy_region->set_eden();
1823   // Make sure it's full.
1824   dummy_region->set_top(dummy_region->end());
1825   G1AllocRegion::setup(this, dummy_region);
1826 
1827   _allocator->init_mutator_alloc_region();
1828 
1829   // Do create of the monitoring and management support so that
1830   // values in the heap have been properly initialized.
1831   _g1mm = new G1MonitoringSupport(this);
1832 
1833   G1StringDedup::initialize();
1834 
1835   _preserved_marks_set.init(ParallelGCThreads);
1836 
1837   _collection_set.initialize(max_regions());
1838 
1839   return JNI_OK;
1840 }
1841 
1842 void G1CollectedHeap::stop() {
1843   // Stop all concurrent threads. We do this to make sure these threads
1844   // do not continue to execute and access resources (e.g. logging)
1845   // that are destroyed during shutdown.
1846   _cg1r->stop();
1847   _cmThread->stop();
1848   if (G1StringDedup::is_enabled()) {
1849     G1StringDedup::stop();
1850   }
1851 }
1852 
1853 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1854   return HeapRegion::max_region_size();
1855 }
1856 
1857 void G1CollectedHeap::post_initialize() {
1858   ref_processing_init();
1859 }
1860 
1861 void G1CollectedHeap::ref_processing_init() {
1862   // Reference processing in G1 currently works as follows:
1863   //
1864   // * There are two reference processor instances. One is
1865   //   used to record and process discovered references
1866   //   during concurrent marking; the other is used to
1867   //   record and process references during STW pauses
1868   //   (both full and incremental).
1869   // * Both ref processors need to 'span' the entire heap as
1870   //   the regions in the collection set may be dotted around.
1871   //
1872   // * For the concurrent marking ref processor:
1873   //   * Reference discovery is enabled at initial marking.
1874   //   * Reference discovery is disabled and the discovered
1875   //     references processed etc during remarking.
1876   //   * Reference discovery is MT (see below).
1877   //   * Reference discovery requires a barrier (see below).
1878   //   * Reference processing may or may not be MT
1879   //     (depending on the value of ParallelRefProcEnabled
1880   //     and ParallelGCThreads).
1881   //   * A full GC disables reference discovery by the CM
1882   //     ref processor and abandons any entries on it's
1883   //     discovered lists.
1884   //
1885   // * For the STW processor:
1886   //   * Non MT discovery is enabled at the start of a full GC.
1887   //   * Processing and enqueueing during a full GC is non-MT.
1888   //   * During a full GC, references are processed after marking.
1889   //
1890   //   * Discovery (may or may not be MT) is enabled at the start
1891   //     of an incremental evacuation pause.
1892   //   * References are processed near the end of a STW evacuation pause.
1893   //   * For both types of GC:
1894   //     * Discovery is atomic - i.e. not concurrent.
1895   //     * Reference discovery will not need a barrier.
1896 
1897   MemRegion mr = reserved_region();
1898 
1899   // Concurrent Mark ref processor
1900   _ref_processor_cm =
1901     new ReferenceProcessor(mr,    // span
1902                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
1903                                 // mt processing
1904                            ParallelGCThreads,
1905                                 // degree of mt processing
1906                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1907                                 // mt discovery
1908                            MAX2(ParallelGCThreads, ConcGCThreads),
1909                                 // degree of mt discovery
1910                            false,
1911                                 // Reference discovery is not atomic
1912                            &_is_alive_closure_cm);
1913                                 // is alive closure
1914                                 // (for efficiency/performance)
1915 
1916   // STW ref processor
1917   _ref_processor_stw =
1918     new ReferenceProcessor(mr,    // span
1919                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
1920                                 // mt processing
1921                            ParallelGCThreads,
1922                                 // degree of mt processing
1923                            (ParallelGCThreads > 1),
1924                                 // mt discovery
1925                            ParallelGCThreads,
1926                                 // degree of mt discovery
1927                            true,
1928                                 // Reference discovery is atomic
1929                            &_is_alive_closure_stw);
1930                                 // is alive closure
1931                                 // (for efficiency/performance)
1932 }
1933 
1934 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1935   return _collector_policy;
1936 }
1937 
1938 size_t G1CollectedHeap::capacity() const {
1939   return _hrm.length() * HeapRegion::GrainBytes;
1940 }
1941 
1942 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1943   hr->reset_gc_time_stamp();
1944 }
1945 
1946 #ifndef PRODUCT
1947 
1948 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1949 private:
1950   unsigned _gc_time_stamp;
1951   bool _failures;
1952 
1953 public:
1954   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1955     _gc_time_stamp(gc_time_stamp), _failures(false) { }
1956 
1957   virtual bool doHeapRegion(HeapRegion* hr) {
1958     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1959     if (_gc_time_stamp != region_gc_time_stamp) {
1960       log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1961                             region_gc_time_stamp, _gc_time_stamp);
1962       _failures = true;
1963     }
1964     return false;
1965   }
1966 
1967   bool failures() { return _failures; }
1968 };
1969 
1970 void G1CollectedHeap::check_gc_time_stamps() {
1971   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1972   heap_region_iterate(&cl);
1973   guarantee(!cl.failures(), "all GC time stamps should have been reset");
1974 }
1975 #endif // PRODUCT
1976 
1977 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1978   _hot_card_cache->drain(cl, worker_i);
1979 }
1980 
1981 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1982   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1983   size_t n_completed_buffers = 0;
1984   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1985     n_completed_buffers++;
1986   }
1987   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1988   dcqs.clear_n_completed_buffers();
1989   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1990 }
1991 
1992 // Computes the sum of the storage used by the various regions.
1993 size_t G1CollectedHeap::used() const {
1994   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1995   if (_archive_allocator != NULL) {
1996     result += _archive_allocator->used();
1997   }
1998   return result;
1999 }
2000 
2001 size_t G1CollectedHeap::used_unlocked() const {
2002   return _summary_bytes_used;
2003 }
2004 
2005 class SumUsedClosure: public HeapRegionClosure {
2006   size_t _used;
2007 public:
2008   SumUsedClosure() : _used(0) {}
2009   bool doHeapRegion(HeapRegion* r) {
2010     _used += r->used();
2011     return false;
2012   }
2013   size_t result() { return _used; }
2014 };
2015 
2016 size_t G1CollectedHeap::recalculate_used() const {
2017   double recalculate_used_start = os::elapsedTime();
2018 
2019   SumUsedClosure blk;
2020   heap_region_iterate(&blk);
2021 
2022   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2023   return blk.result();
2024 }
2025 
2026 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2027   switch (cause) {
2028     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2029     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2030     case GCCause::_update_allocation_context_stats_inc: return true;
2031     case GCCause::_wb_conc_mark:                        return true;
2032     default :                                           return false;
2033   }
2034 }
2035 
2036 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2037   switch (cause) {
2038     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2039     case GCCause::_g1_humongous_allocation: return true;
2040     default:                                return is_user_requested_concurrent_full_gc(cause);
2041   }
2042 }
2043 
2044 #ifndef PRODUCT
2045 void G1CollectedHeap::allocate_dummy_regions() {
2046   // Let's fill up most of the region
2047   size_t word_size = HeapRegion::GrainWords - 1024;
2048   // And as a result the region we'll allocate will be humongous.
2049   guarantee(is_humongous(word_size), "sanity");
2050 
2051   // _filler_array_max_size is set to humongous object threshold
2052   // but temporarily change it to use CollectedHeap::fill_with_object().
2053   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2054 
2055   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2056     // Let's use the existing mechanism for the allocation
2057     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2058                                                  AllocationContext::system());
2059     if (dummy_obj != NULL) {
2060       MemRegion mr(dummy_obj, word_size);
2061       CollectedHeap::fill_with_object(mr);
2062     } else {
2063       // If we can't allocate once, we probably cannot allocate
2064       // again. Let's get out of the loop.
2065       break;
2066     }
2067   }
2068 }
2069 #endif // !PRODUCT
2070 
2071 void G1CollectedHeap::increment_old_marking_cycles_started() {
2072   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2073          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2074          "Wrong marking cycle count (started: %d, completed: %d)",
2075          _old_marking_cycles_started, _old_marking_cycles_completed);
2076 
2077   _old_marking_cycles_started++;
2078 }
2079 
2080 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2081   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2082 
2083   // We assume that if concurrent == true, then the caller is a
2084   // concurrent thread that was joined the Suspendible Thread
2085   // Set. If there's ever a cheap way to check this, we should add an
2086   // assert here.
2087 
2088   // Given that this method is called at the end of a Full GC or of a
2089   // concurrent cycle, and those can be nested (i.e., a Full GC can
2090   // interrupt a concurrent cycle), the number of full collections
2091   // completed should be either one (in the case where there was no
2092   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2093   // behind the number of full collections started.
2094 
2095   // This is the case for the inner caller, i.e. a Full GC.
2096   assert(concurrent ||
2097          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2098          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2099          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2100          "is inconsistent with _old_marking_cycles_completed = %u",
2101          _old_marking_cycles_started, _old_marking_cycles_completed);
2102 
2103   // This is the case for the outer caller, i.e. the concurrent cycle.
2104   assert(!concurrent ||
2105          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2106          "for outer caller (concurrent cycle): "
2107          "_old_marking_cycles_started = %u "
2108          "is inconsistent with _old_marking_cycles_completed = %u",
2109          _old_marking_cycles_started, _old_marking_cycles_completed);
2110 
2111   _old_marking_cycles_completed += 1;
2112 
2113   // We need to clear the "in_progress" flag in the CM thread before
2114   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2115   // is set) so that if a waiter requests another System.gc() it doesn't
2116   // incorrectly see that a marking cycle is still in progress.
2117   if (concurrent) {
2118     _cmThread->set_idle();
2119   }
2120 
2121   // This notify_all() will ensure that a thread that called
2122   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2123   // and it's waiting for a full GC to finish will be woken up. It is
2124   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2125   FullGCCount_lock->notify_all();
2126 }
2127 
2128 void G1CollectedHeap::collect(GCCause::Cause cause) {
2129   assert_heap_not_locked();
2130 
2131   uint gc_count_before;
2132   uint old_marking_count_before;
2133   uint full_gc_count_before;
2134   bool retry_gc;
2135 
2136   do {
2137     retry_gc = false;
2138 
2139     {
2140       MutexLocker ml(Heap_lock);
2141 
2142       // Read the GC count while holding the Heap_lock
2143       gc_count_before = total_collections();
2144       full_gc_count_before = total_full_collections();
2145       old_marking_count_before = _old_marking_cycles_started;
2146     }
2147 
2148     if (should_do_concurrent_full_gc(cause)) {
2149       // Schedule an initial-mark evacuation pause that will start a
2150       // concurrent cycle. We're setting word_size to 0 which means that
2151       // we are not requesting a post-GC allocation.
2152       VM_G1IncCollectionPause op(gc_count_before,
2153                                  0,     /* word_size */
2154                                  true,  /* should_initiate_conc_mark */
2155                                  g1_policy()->max_pause_time_ms(),
2156                                  cause);
2157       op.set_allocation_context(AllocationContext::current());
2158 
2159       VMThread::execute(&op);
2160       if (!op.pause_succeeded()) {
2161         if (old_marking_count_before == _old_marking_cycles_started) {
2162           retry_gc = op.should_retry_gc();
2163         } else {
2164           // A Full GC happened while we were trying to schedule the
2165           // initial-mark GC. No point in starting a new cycle given
2166           // that the whole heap was collected anyway.
2167         }
2168 
2169         if (retry_gc) {
2170           if (GCLocker::is_active_and_needs_gc()) {
2171             GCLocker::stall_until_clear();
2172           }
2173         }
2174       }
2175     } else {
2176       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2177           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2178 
2179         // Schedule a standard evacuation pause. We're setting word_size
2180         // to 0 which means that we are not requesting a post-GC allocation.
2181         VM_G1IncCollectionPause op(gc_count_before,
2182                                    0,     /* word_size */
2183                                    false, /* should_initiate_conc_mark */
2184                                    g1_policy()->max_pause_time_ms(),
2185                                    cause);
2186         VMThread::execute(&op);
2187       } else {
2188         // Schedule a Full GC.
2189         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2190         VMThread::execute(&op);
2191       }
2192     }
2193   } while (retry_gc);
2194 }
2195 
2196 bool G1CollectedHeap::is_in(const void* p) const {
2197   if (_hrm.reserved().contains(p)) {
2198     // Given that we know that p is in the reserved space,
2199     // heap_region_containing() should successfully
2200     // return the containing region.
2201     HeapRegion* hr = heap_region_containing(p);
2202     return hr->is_in(p);
2203   } else {
2204     return false;
2205   }
2206 }
2207 
2208 #ifdef ASSERT
2209 bool G1CollectedHeap::is_in_exact(const void* p) const {
2210   bool contains = reserved_region().contains(p);
2211   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2212   if (contains && available) {
2213     return true;
2214   } else {
2215     return false;
2216   }
2217 }
2218 #endif
2219 
2220 // Iteration functions.
2221 
2222 // Iterates an ObjectClosure over all objects within a HeapRegion.
2223 
2224 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2225   ObjectClosure* _cl;
2226 public:
2227   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2228   bool doHeapRegion(HeapRegion* r) {
2229     if (!r->is_continues_humongous()) {
2230       r->object_iterate(_cl);
2231     }
2232     return false;
2233   }
2234 };
2235 
2236 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2237   IterateObjectClosureRegionClosure blk(cl);
2238   heap_region_iterate(&blk);
2239 }
2240 
2241 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2242   _hrm.iterate(cl);
2243 }
2244 
2245 void G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2246                                               uint worker_id,
2247                                               HeapRegionClaimerBase *hrclaimer) const {
2248   _hrm.par_iterate(cl, worker_id, hrclaimer);
2249 }
2250 
2251 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2252   _collection_set.iterate(cl);
2253 }
2254 
2255 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2256   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2257 }
2258 
2259 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2260   HeapRegion* hr = heap_region_containing(addr);
2261   return hr->block_start(addr);
2262 }
2263 
2264 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2265   HeapRegion* hr = heap_region_containing(addr);
2266   return hr->block_size(addr);
2267 }
2268 
2269 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2270   HeapRegion* hr = heap_region_containing(addr);
2271   return hr->block_is_obj(addr);
2272 }
2273 
2274 bool G1CollectedHeap::supports_tlab_allocation() const {
2275   return true;
2276 }
2277 
2278 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2279   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2280 }
2281 
2282 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2283   return _eden.length() * HeapRegion::GrainBytes;
2284 }
2285 
2286 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2287 // must be equal to the humongous object limit.
2288 size_t G1CollectedHeap::max_tlab_size() const {
2289   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2290 }
2291 
2292 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2293   AllocationContext_t context = AllocationContext::current();
2294   return _allocator->unsafe_max_tlab_alloc(context);
2295 }
2296 
2297 size_t G1CollectedHeap::max_capacity() const {
2298   return _hrm.reserved().byte_size();
2299 }
2300 
2301 jlong G1CollectedHeap::millis_since_last_gc() {
2302   // See the notes in GenCollectedHeap::millis_since_last_gc()
2303   // for more information about the implementation.
2304   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2305     _g1_policy->collection_pause_end_millis();
2306   if (ret_val < 0) {
2307     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2308       ". returning zero instead.", ret_val);
2309     return 0;
2310   }
2311   return ret_val;
2312 }
2313 
2314 void G1CollectedHeap::prepare_for_verify() {
2315   _verifier->prepare_for_verify();
2316 }
2317 
2318 void G1CollectedHeap::verify(VerifyOption vo) {
2319   _verifier->verify(vo);
2320 }
2321 
2322 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2323   return true;
2324 }
2325 
2326 const char* const* G1CollectedHeap::concurrent_phases() const {
2327   return _cmThread->concurrent_phases();
2328 }
2329 
2330 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2331   return _cmThread->request_concurrent_phase(phase);
2332 }
2333 
2334 class PrintRegionClosure: public HeapRegionClosure {
2335   outputStream* _st;
2336 public:
2337   PrintRegionClosure(outputStream* st) : _st(st) {}
2338   bool doHeapRegion(HeapRegion* r) {
2339     r->print_on(_st);
2340     return false;
2341   }
2342 };
2343 
2344 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2345                                        const HeapRegion* hr,
2346                                        const VerifyOption vo) const {
2347   switch (vo) {
2348   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2349   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2350   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
2351   default:                            ShouldNotReachHere();
2352   }
2353   return false; // keep some compilers happy
2354 }
2355 
2356 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2357                                        const VerifyOption vo) const {
2358   switch (vo) {
2359   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2360   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2361   case VerifyOption_G1UseMarkWord: {
2362     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2363     return !obj->is_gc_marked() && !hr->is_archive();
2364   }
2365   default:                            ShouldNotReachHere();
2366   }
2367   return false; // keep some compilers happy
2368 }
2369 
2370 void G1CollectedHeap::print_heap_regions() const {
2371   Log(gc, heap, region) log;
2372   if (log.is_trace()) {
2373     ResourceMark rm;
2374     print_regions_on(log.trace_stream());
2375   }
2376 }
2377 
2378 void G1CollectedHeap::print_on(outputStream* st) const {
2379   st->print(" %-20s", "garbage-first heap");
2380   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2381             capacity()/K, used_unlocked()/K);
2382   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2383             p2i(_hrm.reserved().start()),
2384             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2385             p2i(_hrm.reserved().end()));
2386   st->cr();
2387   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2388   uint young_regions = young_regions_count();
2389   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2390             (size_t) young_regions * HeapRegion::GrainBytes / K);
2391   uint survivor_regions = survivor_regions_count();
2392   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2393             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2394   st->cr();
2395   MetaspaceAux::print_on(st);
2396 }
2397 
2398 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2399   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2400                "HS=humongous(starts), HC=humongous(continues), "
2401                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2402                "AC=allocation context, "
2403                "TAMS=top-at-mark-start (previous, next)");
2404   PrintRegionClosure blk(st);
2405   heap_region_iterate(&blk);
2406 }
2407 
2408 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2409   print_on(st);
2410 
2411   // Print the per-region information.
2412   print_regions_on(st);
2413 }
2414 
2415 void G1CollectedHeap::print_on_error(outputStream* st) const {
2416   this->CollectedHeap::print_on_error(st);
2417 
2418   if (_cm != NULL) {
2419     st->cr();
2420     _cm->print_on_error(st);
2421   }
2422 }
2423 
2424 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2425   workers()->print_worker_threads_on(st);
2426   _cmThread->print_on(st);
2427   st->cr();
2428   _cm->print_worker_threads_on(st);
2429   _cg1r->print_worker_threads_on(st); // also prints the sample thread
2430   if (G1StringDedup::is_enabled()) {
2431     G1StringDedup::print_worker_threads_on(st);
2432   }
2433 }
2434 
2435 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2436   workers()->threads_do(tc);
2437   tc->do_thread(_cmThread);
2438   _cm->threads_do(tc);
2439   _cg1r->threads_do(tc); // also iterates over the sample thread
2440   if (G1StringDedup::is_enabled()) {
2441     G1StringDedup::threads_do(tc);
2442   }
2443 }
2444 
2445 void G1CollectedHeap::print_tracing_info() const {
2446   g1_rem_set()->print_summary_info();
2447   concurrent_mark()->print_summary_info();
2448 }
2449 
2450 #ifndef PRODUCT
2451 // Helpful for debugging RSet issues.
2452 
2453 class PrintRSetsClosure : public HeapRegionClosure {
2454 private:
2455   const char* _msg;
2456   size_t _occupied_sum;
2457 
2458 public:
2459   bool doHeapRegion(HeapRegion* r) {
2460     HeapRegionRemSet* hrrs = r->rem_set();
2461     size_t occupied = hrrs->occupied();
2462     _occupied_sum += occupied;
2463 
2464     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2465     if (occupied == 0) {
2466       tty->print_cr("  RSet is empty");
2467     } else {
2468       hrrs->print();
2469     }
2470     tty->print_cr("----------");
2471     return false;
2472   }
2473 
2474   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2475     tty->cr();
2476     tty->print_cr("========================================");
2477     tty->print_cr("%s", msg);
2478     tty->cr();
2479   }
2480 
2481   ~PrintRSetsClosure() {
2482     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2483     tty->print_cr("========================================");
2484     tty->cr();
2485   }
2486 };
2487 
2488 void G1CollectedHeap::print_cset_rsets() {
2489   PrintRSetsClosure cl("Printing CSet RSets");
2490   collection_set_iterate(&cl);
2491 }
2492 
2493 void G1CollectedHeap::print_all_rsets() {
2494   PrintRSetsClosure cl("Printing All RSets");;
2495   heap_region_iterate(&cl);
2496 }
2497 #endif // PRODUCT
2498 
2499 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2500 
2501   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2502   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2503   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2504 
2505   size_t eden_capacity_bytes =
2506     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2507 
2508   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2509   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2510                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2511 }
2512 
2513 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2514   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2515                        stats->unused(), stats->used(), stats->region_end_waste(),
2516                        stats->regions_filled(), stats->direct_allocated(),
2517                        stats->failure_used(), stats->failure_waste());
2518 }
2519 
2520 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2521   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2522   gc_tracer->report_gc_heap_summary(when, heap_summary);
2523 
2524   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2525   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2526 }
2527 
2528 G1CollectedHeap* G1CollectedHeap::heap() {
2529   CollectedHeap* heap = Universe::heap();
2530   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2531   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2532   return (G1CollectedHeap*)heap;
2533 }
2534 
2535 void G1CollectedHeap::gc_prologue(bool full) {
2536   // always_do_update_barrier = false;
2537   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2538 
2539   // This summary needs to be printed before incrementing total collections.
2540   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2541 
2542   // Update common counters.
2543   increment_total_collections(full /* full gc */);
2544   if (full) {
2545     increment_old_marking_cycles_started();
2546     reset_gc_time_stamp();
2547   } else {
2548     increment_gc_time_stamp();
2549   }
2550 
2551   // Fill TLAB's and such
2552   double start = os::elapsedTime();
2553   accumulate_statistics_all_tlabs();
2554   ensure_parsability(true);
2555   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2556 }
2557 
2558 void G1CollectedHeap::gc_epilogue(bool full) {
2559   // Update common counters.
2560   if (full) {
2561     // Update the number of full collections that have been completed.
2562     increment_old_marking_cycles_completed(false /* concurrent */);
2563   }
2564 
2565   // We are at the end of the GC. Total collections has already been increased.
2566   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2567 
2568   // FIXME: what is this about?
2569   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2570   // is set.
2571 #if defined(COMPILER2) || INCLUDE_JVMCI
2572   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2573 #endif
2574   // always_do_update_barrier = true;
2575 
2576   double start = os::elapsedTime();
2577   resize_all_tlabs();
2578   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2579 
2580   allocation_context_stats().update(full);
2581 
2582   MemoryService::track_memory_usage();
2583   // We have just completed a GC. Update the soft reference
2584   // policy with the new heap occupancy
2585   Universe::update_heap_info_at_gc();
2586 }
2587 
2588 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2589                                                uint gc_count_before,
2590                                                bool* succeeded,
2591                                                GCCause::Cause gc_cause) {
2592   assert_heap_not_locked_and_not_at_safepoint();
2593   VM_G1IncCollectionPause op(gc_count_before,
2594                              word_size,
2595                              false, /* should_initiate_conc_mark */
2596                              g1_policy()->max_pause_time_ms(),
2597                              gc_cause);
2598 
2599   op.set_allocation_context(AllocationContext::current());
2600   VMThread::execute(&op);
2601 
2602   HeapWord* result = op.result();
2603   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2604   assert(result == NULL || ret_succeeded,
2605          "the result should be NULL if the VM did not succeed");
2606   *succeeded = ret_succeeded;
2607 
2608   assert_heap_not_locked();
2609   return result;
2610 }
2611 
2612 void
2613 G1CollectedHeap::doConcurrentMark() {
2614   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2615   if (!_cmThread->in_progress()) {
2616     _cmThread->set_started();
2617     CGC_lock->notify();
2618   }
2619 }
2620 
2621 size_t G1CollectedHeap::pending_card_num() {
2622   size_t extra_cards = 0;
2623   JavaThread *curr = Threads::first();
2624   while (curr != NULL) {
2625     DirtyCardQueue& dcq = curr->dirty_card_queue();
2626     extra_cards += dcq.size();
2627     curr = curr->next();
2628   }
2629   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2630   size_t buffer_size = dcqs.buffer_size();
2631   size_t buffer_num = dcqs.completed_buffers_num();
2632 
2633   return buffer_size * buffer_num + extra_cards;
2634 }
2635 
2636 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2637  private:
2638   size_t _total_humongous;
2639   size_t _candidate_humongous;
2640 
2641   DirtyCardQueue _dcq;
2642 
2643   // We don't nominate objects with many remembered set entries, on
2644   // the assumption that such objects are likely still live.
2645   bool is_remset_small(HeapRegion* region) const {
2646     HeapRegionRemSet* const rset = region->rem_set();
2647     return G1EagerReclaimHumongousObjectsWithStaleRefs
2648       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2649       : rset->is_empty();
2650   }
2651 
2652   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2653     assert(region->is_starts_humongous(), "Must start a humongous object");
2654 
2655     oop obj = oop(region->bottom());
2656 
2657     // Dead objects cannot be eager reclaim candidates. Due to class
2658     // unloading it is unsafe to query their classes so we return early.
2659     if (heap->is_obj_dead(obj, region)) {
2660       return false;
2661     }
2662 
2663     // Candidate selection must satisfy the following constraints
2664     // while concurrent marking is in progress:
2665     //
2666     // * In order to maintain SATB invariants, an object must not be
2667     // reclaimed if it was allocated before the start of marking and
2668     // has not had its references scanned.  Such an object must have
2669     // its references (including type metadata) scanned to ensure no
2670     // live objects are missed by the marking process.  Objects
2671     // allocated after the start of concurrent marking don't need to
2672     // be scanned.
2673     //
2674     // * An object must not be reclaimed if it is on the concurrent
2675     // mark stack.  Objects allocated after the start of concurrent
2676     // marking are never pushed on the mark stack.
2677     //
2678     // Nominating only objects allocated after the start of concurrent
2679     // marking is sufficient to meet both constraints.  This may miss
2680     // some objects that satisfy the constraints, but the marking data
2681     // structures don't support efficiently performing the needed
2682     // additional tests or scrubbing of the mark stack.
2683     //
2684     // However, we presently only nominate is_typeArray() objects.
2685     // A humongous object containing references induces remembered
2686     // set entries on other regions.  In order to reclaim such an
2687     // object, those remembered sets would need to be cleaned up.
2688     //
2689     // We also treat is_typeArray() objects specially, allowing them
2690     // to be reclaimed even if allocated before the start of
2691     // concurrent mark.  For this we rely on mark stack insertion to
2692     // exclude is_typeArray() objects, preventing reclaiming an object
2693     // that is in the mark stack.  We also rely on the metadata for
2694     // such objects to be built-in and so ensured to be kept live.
2695     // Frequent allocation and drop of large binary blobs is an
2696     // important use case for eager reclaim, and this special handling
2697     // may reduce needed headroom.
2698 
2699     return obj->is_typeArray() && is_remset_small(region);
2700   }
2701 
2702  public:
2703   RegisterHumongousWithInCSetFastTestClosure()
2704   : _total_humongous(0),
2705     _candidate_humongous(0),
2706     _dcq(&JavaThread::dirty_card_queue_set()) {
2707   }
2708 
2709   virtual bool doHeapRegion(HeapRegion* r) {
2710     if (!r->is_starts_humongous()) {
2711       return false;
2712     }
2713     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2714 
2715     bool is_candidate = humongous_region_is_candidate(g1h, r);
2716     uint rindex = r->hrm_index();
2717     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2718     if (is_candidate) {
2719       _candidate_humongous++;
2720       g1h->register_humongous_region_with_cset(rindex);
2721       // Is_candidate already filters out humongous object with large remembered sets.
2722       // If we have a humongous object with a few remembered sets, we simply flush these
2723       // remembered set entries into the DCQS. That will result in automatic
2724       // re-evaluation of their remembered set entries during the following evacuation
2725       // phase.
2726       if (!r->rem_set()->is_empty()) {
2727         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2728                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2729         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2730         HeapRegionRemSetIterator hrrs(r->rem_set());
2731         size_t card_index;
2732         while (hrrs.has_next(card_index)) {
2733           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2734           // The remembered set might contain references to already freed
2735           // regions. Filter out such entries to avoid failing card table
2736           // verification.
2737           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2738             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2739               *card_ptr = CardTableModRefBS::dirty_card_val();
2740               _dcq.enqueue(card_ptr);
2741             }
2742           }
2743         }
2744         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2745                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2746                hrrs.n_yielded(), r->rem_set()->occupied());
2747         r->rem_set()->clear_locked();
2748       }
2749       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2750     }
2751     _total_humongous++;
2752 
2753     return false;
2754   }
2755 
2756   size_t total_humongous() const { return _total_humongous; }
2757   size_t candidate_humongous() const { return _candidate_humongous; }
2758 
2759   void flush_rem_set_entries() { _dcq.flush(); }
2760 };
2761 
2762 void G1CollectedHeap::register_humongous_regions_with_cset() {
2763   if (!G1EagerReclaimHumongousObjects) {
2764     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2765     return;
2766   }
2767   double time = os::elapsed_counter();
2768 
2769   // Collect reclaim candidate information and register candidates with cset.
2770   RegisterHumongousWithInCSetFastTestClosure cl;
2771   heap_region_iterate(&cl);
2772 
2773   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2774   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2775                                                                   cl.total_humongous(),
2776                                                                   cl.candidate_humongous());
2777   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2778 
2779   // Finally flush all remembered set entries to re-check into the global DCQS.
2780   cl.flush_rem_set_entries();
2781 }
2782 
2783 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2784   public:
2785     bool doHeapRegion(HeapRegion* hr) {
2786       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2787         hr->verify_rem_set();
2788       }
2789       return false;
2790     }
2791 };
2792 
2793 uint G1CollectedHeap::num_task_queues() const {
2794   return _task_queues->size();
2795 }
2796 
2797 #if TASKQUEUE_STATS
2798 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2799   st->print_raw_cr("GC Task Stats");
2800   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2801   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2802 }
2803 
2804 void G1CollectedHeap::print_taskqueue_stats() const {
2805   if (!log_is_enabled(Trace, gc, task, stats)) {
2806     return;
2807   }
2808   Log(gc, task, stats) log;
2809   ResourceMark rm;
2810   outputStream* st = log.trace_stream();
2811 
2812   print_taskqueue_stats_hdr(st);
2813 
2814   TaskQueueStats totals;
2815   const uint n = num_task_queues();
2816   for (uint i = 0; i < n; ++i) {
2817     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2818     totals += task_queue(i)->stats;
2819   }
2820   st->print_raw("tot "); totals.print(st); st->cr();
2821 
2822   DEBUG_ONLY(totals.verify());
2823 }
2824 
2825 void G1CollectedHeap::reset_taskqueue_stats() {
2826   const uint n = num_task_queues();
2827   for (uint i = 0; i < n; ++i) {
2828     task_queue(i)->stats.reset();
2829   }
2830 }
2831 #endif // TASKQUEUE_STATS
2832 
2833 void G1CollectedHeap::wait_for_root_region_scanning() {
2834   double scan_wait_start = os::elapsedTime();
2835   // We have to wait until the CM threads finish scanning the
2836   // root regions as it's the only way to ensure that all the
2837   // objects on them have been correctly scanned before we start
2838   // moving them during the GC.
2839   bool waited = _cm->root_regions()->wait_until_scan_finished();
2840   double wait_time_ms = 0.0;
2841   if (waited) {
2842     double scan_wait_end = os::elapsedTime();
2843     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2844   }
2845   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2846 }
2847 
2848 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2849 private:
2850   G1HRPrinter* _hr_printer;
2851 public:
2852   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2853 
2854   virtual bool doHeapRegion(HeapRegion* r) {
2855     _hr_printer->cset(r);
2856     return false;
2857   }
2858 };
2859 
2860 void G1CollectedHeap::start_new_collection_set() {
2861   collection_set()->start_incremental_building();
2862 
2863   clear_cset_fast_test();
2864 
2865   guarantee(_eden.length() == 0, "eden should have been cleared");
2866   g1_policy()->transfer_survivors_to_cset(survivor());
2867 }
2868 
2869 bool
2870 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2871   assert_at_safepoint(true /* should_be_vm_thread */);
2872   guarantee(!is_gc_active(), "collection is not reentrant");
2873 
2874   if (GCLocker::check_active_before_gc()) {
2875     return false;
2876   }
2877 
2878   _gc_timer_stw->register_gc_start();
2879 
2880   GCIdMark gc_id_mark;
2881   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2882 
2883   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2884   ResourceMark rm;
2885 
2886   g1_policy()->note_gc_start();
2887 
2888   wait_for_root_region_scanning();
2889 
2890   print_heap_before_gc();
2891   print_heap_regions();
2892   trace_heap_before_gc(_gc_tracer_stw);
2893 
2894   _verifier->verify_region_sets_optional();
2895   _verifier->verify_dirty_young_regions();
2896 
2897   // We should not be doing initial mark unless the conc mark thread is running
2898   if (!_cmThread->should_terminate()) {
2899     // This call will decide whether this pause is an initial-mark
2900     // pause. If it is, during_initial_mark_pause() will return true
2901     // for the duration of this pause.
2902     g1_policy()->decide_on_conc_mark_initiation();
2903   }
2904 
2905   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2906   assert(!collector_state()->during_initial_mark_pause() ||
2907           collector_state()->gcs_are_young(), "sanity");
2908 
2909   // We also do not allow mixed GCs during marking.
2910   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2911 
2912   // Record whether this pause is an initial mark. When the current
2913   // thread has completed its logging output and it's safe to signal
2914   // the CM thread, the flag's value in the policy has been reset.
2915   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2916 
2917   // Inner scope for scope based logging, timers, and stats collection
2918   {
2919     EvacuationInfo evacuation_info;
2920 
2921     if (collector_state()->during_initial_mark_pause()) {
2922       // We are about to start a marking cycle, so we increment the
2923       // full collection counter.
2924       increment_old_marking_cycles_started();
2925       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2926     }
2927 
2928     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2929 
2930     GCTraceCPUTime tcpu;
2931 
2932     FormatBuffer<> gc_string("Pause ");
2933     if (collector_state()->during_initial_mark_pause()) {
2934       gc_string.append("Initial Mark");
2935     } else if (collector_state()->gcs_are_young()) {
2936       gc_string.append("Young");
2937     } else {
2938       gc_string.append("Mixed");
2939     }
2940     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2941 
2942     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2943                                                                   workers()->active_workers(),
2944                                                                   Threads::number_of_non_daemon_threads());
2945     workers()->update_active_workers(active_workers);
2946     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2947 
2948     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2949     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
2950 
2951     // If the secondary_free_list is not empty, append it to the
2952     // free_list. No need to wait for the cleanup operation to finish;
2953     // the region allocation code will check the secondary_free_list
2954     // and wait if necessary. If the G1StressConcRegionFreeing flag is
2955     // set, skip this step so that the region allocation code has to
2956     // get entries from the secondary_free_list.
2957     if (!G1StressConcRegionFreeing) {
2958       append_secondary_free_list_if_not_empty_with_lock();
2959     }
2960 
2961     G1HeapTransition heap_transition(this);
2962     size_t heap_used_bytes_before_gc = used();
2963 
2964     // Don't dynamically change the number of GC threads this early.  A value of
2965     // 0 is used to indicate serial work.  When parallel work is done,
2966     // it will be set.
2967 
2968     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2969       IsGCActiveMark x;
2970 
2971       gc_prologue(false);
2972 
2973       if (VerifyRememberedSets) {
2974         log_info(gc, verify)("[Verifying RemSets before GC]");
2975         VerifyRegionRemSetClosure v_cl;
2976         heap_region_iterate(&v_cl);
2977       }
2978 
2979       _verifier->verify_before_gc();
2980 
2981       _verifier->check_bitmaps("GC Start");
2982 
2983 #if defined(COMPILER2) || INCLUDE_JVMCI
2984       DerivedPointerTable::clear();
2985 #endif
2986 
2987       // Please see comment in g1CollectedHeap.hpp and
2988       // G1CollectedHeap::ref_processing_init() to see how
2989       // reference processing currently works in G1.
2990 
2991       // Enable discovery in the STW reference processor
2992       if (g1_policy()->should_process_references()) {
2993         ref_processor_stw()->enable_discovery();
2994       } else {
2995         ref_processor_stw()->disable_discovery();
2996       }
2997 
2998       {
2999         // We want to temporarily turn off discovery by the
3000         // CM ref processor, if necessary, and turn it back on
3001         // on again later if we do. Using a scoped
3002         // NoRefDiscovery object will do this.
3003         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3004 
3005         // Forget the current alloc region (we might even choose it to be part
3006         // of the collection set!).
3007         _allocator->release_mutator_alloc_region();
3008 
3009         // This timing is only used by the ergonomics to handle our pause target.
3010         // It is unclear why this should not include the full pause. We will
3011         // investigate this in CR 7178365.
3012         //
3013         // Preserving the old comment here if that helps the investigation:
3014         //
3015         // The elapsed time induced by the start time below deliberately elides
3016         // the possible verification above.
3017         double sample_start_time_sec = os::elapsedTime();
3018 
3019         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3020 
3021         if (collector_state()->during_initial_mark_pause()) {
3022           concurrent_mark()->checkpointRootsInitialPre();
3023         }
3024 
3025         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3026 
3027         evacuation_info.set_collectionset_regions(collection_set()->region_length());
3028 
3029         // Make sure the remembered sets are up to date. This needs to be
3030         // done before register_humongous_regions_with_cset(), because the
3031         // remembered sets are used there to choose eager reclaim candidates.
3032         // If the remembered sets are not up to date we might miss some
3033         // entries that need to be handled.
3034         g1_rem_set()->cleanupHRRS();
3035 
3036         register_humongous_regions_with_cset();
3037 
3038         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3039 
3040         // We call this after finalize_cset() to
3041         // ensure that the CSet has been finalized.
3042         _cm->verify_no_cset_oops();
3043 
3044         if (_hr_printer.is_active()) {
3045           G1PrintCollectionSetClosure cl(&_hr_printer);
3046           _collection_set.iterate(&cl);
3047         }
3048 
3049         // Initialize the GC alloc regions.
3050         _allocator->init_gc_alloc_regions(evacuation_info);
3051 
3052         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3053         pre_evacuate_collection_set();
3054 
3055         // Actually do the work...
3056         evacuate_collection_set(evacuation_info, &per_thread_states);
3057 
3058         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3059 
3060         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3061         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3062 
3063         eagerly_reclaim_humongous_regions();
3064 
3065         record_obj_copy_mem_stats();
3066         _survivor_evac_stats.adjust_desired_plab_sz();
3067         _old_evac_stats.adjust_desired_plab_sz();
3068 
3069         double start = os::elapsedTime();
3070         start_new_collection_set();
3071         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3072 
3073         if (evacuation_failed()) {
3074           set_used(recalculate_used());
3075           if (_archive_allocator != NULL) {
3076             _archive_allocator->clear_used();
3077           }
3078           for (uint i = 0; i < ParallelGCThreads; i++) {
3079             if (_evacuation_failed_info_array[i].has_failed()) {
3080               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3081             }
3082           }
3083         } else {
3084           // The "used" of the the collection set have already been subtracted
3085           // when they were freed.  Add in the bytes evacuated.
3086           increase_used(g1_policy()->bytes_copied_during_gc());
3087         }
3088 
3089         if (collector_state()->during_initial_mark_pause()) {
3090           // We have to do this before we notify the CM threads that
3091           // they can start working to make sure that all the
3092           // appropriate initialization is done on the CM object.
3093           concurrent_mark()->checkpointRootsInitialPost();
3094           collector_state()->set_mark_in_progress(true);
3095           // Note that we don't actually trigger the CM thread at
3096           // this point. We do that later when we're sure that
3097           // the current thread has completed its logging output.
3098         }
3099 
3100         allocate_dummy_regions();
3101 
3102         _allocator->init_mutator_alloc_region();
3103 
3104         {
3105           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3106           if (expand_bytes > 0) {
3107             size_t bytes_before = capacity();
3108             // No need for an ergo logging here,
3109             // expansion_amount() does this when it returns a value > 0.
3110             double expand_ms;
3111             if (!expand(expand_bytes, _workers, &expand_ms)) {
3112               // We failed to expand the heap. Cannot do anything about it.
3113             }
3114             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3115           }
3116         }
3117 
3118         // We redo the verification but now wrt to the new CSet which
3119         // has just got initialized after the previous CSet was freed.
3120         _cm->verify_no_cset_oops();
3121 
3122         // This timing is only used by the ergonomics to handle our pause target.
3123         // It is unclear why this should not include the full pause. We will
3124         // investigate this in CR 7178365.
3125         double sample_end_time_sec = os::elapsedTime();
3126         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3127         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3128         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3129 
3130         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3131         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3132 
3133         if (VerifyRememberedSets) {
3134           log_info(gc, verify)("[Verifying RemSets after GC]");
3135           VerifyRegionRemSetClosure v_cl;
3136           heap_region_iterate(&v_cl);
3137         }
3138 
3139         _verifier->verify_after_gc();
3140         _verifier->check_bitmaps("GC End");
3141 
3142         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3143         ref_processor_stw()->verify_no_references_recorded();
3144 
3145         // CM reference discovery will be re-enabled if necessary.
3146       }
3147 
3148 #ifdef TRACESPINNING
3149       ParallelTaskTerminator::print_termination_counts();
3150 #endif
3151 
3152       gc_epilogue(false);
3153     }
3154 
3155     // Print the remainder of the GC log output.
3156     if (evacuation_failed()) {
3157       log_info(gc)("To-space exhausted");
3158     }
3159 
3160     g1_policy()->print_phases();
3161     heap_transition.print();
3162 
3163     // It is not yet to safe to tell the concurrent mark to
3164     // start as we have some optional output below. We don't want the
3165     // output from the concurrent mark thread interfering with this
3166     // logging output either.
3167 
3168     _hrm.verify_optional();
3169     _verifier->verify_region_sets_optional();
3170 
3171     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3172     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3173 
3174     print_heap_after_gc();
3175     print_heap_regions();
3176     trace_heap_after_gc(_gc_tracer_stw);
3177 
3178     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3179     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3180     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3181     // before any GC notifications are raised.
3182     g1mm()->update_sizes();
3183 
3184     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3185     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3186     _gc_timer_stw->register_gc_end();
3187     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3188   }
3189   // It should now be safe to tell the concurrent mark thread to start
3190   // without its logging output interfering with the logging output
3191   // that came from the pause.
3192 
3193   if (should_start_conc_mark) {
3194     // CAUTION: after the doConcurrentMark() call below,
3195     // the concurrent marking thread(s) could be running
3196     // concurrently with us. Make sure that anything after
3197     // this point does not assume that we are the only GC thread
3198     // running. Note: of course, the actual marking work will
3199     // not start until the safepoint itself is released in
3200     // SuspendibleThreadSet::desynchronize().
3201     doConcurrentMark();
3202   }
3203 
3204   return true;
3205 }
3206 
3207 void G1CollectedHeap::remove_self_forwarding_pointers() {
3208   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3209   workers()->run_task(&rsfp_task);
3210 }
3211 
3212 void G1CollectedHeap::restore_after_evac_failure() {
3213   double remove_self_forwards_start = os::elapsedTime();
3214 
3215   remove_self_forwarding_pointers();
3216   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3217   _preserved_marks_set.restore(&task_executor);
3218 
3219   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3220 }
3221 
3222 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3223   if (!_evacuation_failed) {
3224     _evacuation_failed = true;
3225   }
3226 
3227   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3228   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3229 }
3230 
3231 bool G1ParEvacuateFollowersClosure::offer_termination() {
3232   G1ParScanThreadState* const pss = par_scan_state();
3233   start_term_time();
3234   const bool res = terminator()->offer_termination();
3235   end_term_time();
3236   return res;
3237 }
3238 
3239 void G1ParEvacuateFollowersClosure::do_void() {
3240   G1ParScanThreadState* const pss = par_scan_state();
3241   pss->trim_queue();
3242   do {
3243     pss->steal_and_trim_queue(queues());
3244   } while (!offer_termination());
3245 }
3246 
3247 class G1ParTask : public AbstractGangTask {
3248 protected:
3249   G1CollectedHeap*         _g1h;
3250   G1ParScanThreadStateSet* _pss;
3251   RefToScanQueueSet*       _queues;
3252   G1RootProcessor*         _root_processor;
3253   ParallelTaskTerminator   _terminator;
3254   uint                     _n_workers;
3255 
3256 public:
3257   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3258     : AbstractGangTask("G1 collection"),
3259       _g1h(g1h),
3260       _pss(per_thread_states),
3261       _queues(task_queues),
3262       _root_processor(root_processor),
3263       _terminator(n_workers, _queues),
3264       _n_workers(n_workers)
3265   {}
3266 
3267   void work(uint worker_id) {
3268     if (worker_id >= _n_workers) return;  // no work needed this round
3269 
3270     double start_sec = os::elapsedTime();
3271     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3272 
3273     {
3274       ResourceMark rm;
3275       HandleMark   hm;
3276 
3277       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3278 
3279       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3280       pss->set_ref_processor(rp);
3281 
3282       double start_strong_roots_sec = os::elapsedTime();
3283 
3284       _root_processor->evacuate_roots(pss->closures(), worker_id);
3285 
3286       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3287       // treating the nmethods visited to act as roots for concurrent marking.
3288       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3289       // objects copied by the current evacuation.
3290       _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3291                                                       pss->closures()->weak_codeblobs(),
3292                                                       worker_id);
3293 
3294       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3295 
3296       double term_sec = 0.0;
3297       size_t evac_term_attempts = 0;
3298       {
3299         double start = os::elapsedTime();
3300         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3301         evac.do_void();
3302 
3303         evac_term_attempts = evac.term_attempts();
3304         term_sec = evac.term_time();
3305         double elapsed_sec = os::elapsedTime() - start;
3306         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3307         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3308         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3309       }
3310 
3311       assert(pss->queue_is_empty(), "should be empty");
3312 
3313       if (log_is_enabled(Debug, gc, task, stats)) {
3314         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3315         size_t lab_waste;
3316         size_t lab_undo_waste;
3317         pss->waste(lab_waste, lab_undo_waste);
3318         _g1h->print_termination_stats(worker_id,
3319                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3320                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3321                                       term_sec * 1000.0,                          /* evac term time */
3322                                       evac_term_attempts,                         /* evac term attempts */
3323                                       lab_waste,                                  /* alloc buffer waste */
3324                                       lab_undo_waste                              /* undo waste */
3325                                       );
3326       }
3327 
3328       // Close the inner scope so that the ResourceMark and HandleMark
3329       // destructors are executed here and are included as part of the
3330       // "GC Worker Time".
3331     }
3332     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3333   }
3334 };
3335 
3336 void G1CollectedHeap::print_termination_stats_hdr() {
3337   log_debug(gc, task, stats)("GC Termination Stats");
3338   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3339   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3340   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3341 }
3342 
3343 void G1CollectedHeap::print_termination_stats(uint worker_id,
3344                                               double elapsed_ms,
3345                                               double strong_roots_ms,
3346                                               double term_ms,
3347                                               size_t term_attempts,
3348                                               size_t alloc_buffer_waste,
3349                                               size_t undo_waste) const {
3350   log_debug(gc, task, stats)
3351               ("%3d %9.2f %9.2f %6.2f "
3352                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3353                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3354                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3355                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3356                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3357                alloc_buffer_waste * HeapWordSize / K,
3358                undo_waste * HeapWordSize / K);
3359 }
3360 
3361 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3362 private:
3363   BoolObjectClosure* _is_alive;
3364   G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3365 
3366   int _initial_string_table_size;
3367   int _initial_symbol_table_size;
3368 
3369   bool  _process_strings;
3370   int _strings_processed;
3371   int _strings_removed;
3372 
3373   bool  _process_symbols;
3374   int _symbols_processed;
3375   int _symbols_removed;
3376 
3377   bool _process_string_dedup;
3378 
3379 public:
3380   G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3381     AbstractGangTask("String/Symbol Unlinking"),
3382     _is_alive(is_alive),
3383     _dedup_closure(is_alive, NULL, false),
3384     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3385     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3386     _process_string_dedup(process_string_dedup) {
3387 
3388     _initial_string_table_size = StringTable::the_table()->table_size();
3389     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3390     if (process_strings) {
3391       StringTable::clear_parallel_claimed_index();
3392     }
3393     if (process_symbols) {
3394       SymbolTable::clear_parallel_claimed_index();
3395     }
3396   }
3397 
3398   ~G1StringAndSymbolCleaningTask() {
3399     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3400               "claim value %d after unlink less than initial string table size %d",
3401               StringTable::parallel_claimed_index(), _initial_string_table_size);
3402     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3403               "claim value %d after unlink less than initial symbol table size %d",
3404               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3405 
3406     log_info(gc, stringtable)(
3407         "Cleaned string and symbol table, "
3408         "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3409         "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3410         strings_processed(), strings_removed(),
3411         symbols_processed(), symbols_removed());
3412   }
3413 
3414   void work(uint worker_id) {
3415     int strings_processed = 0;
3416     int strings_removed = 0;
3417     int symbols_processed = 0;
3418     int symbols_removed = 0;
3419     if (_process_strings) {
3420       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3421       Atomic::add(strings_processed, &_strings_processed);
3422       Atomic::add(strings_removed, &_strings_removed);
3423     }
3424     if (_process_symbols) {
3425       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3426       Atomic::add(symbols_processed, &_symbols_processed);
3427       Atomic::add(symbols_removed, &_symbols_removed);
3428     }
3429     if (_process_string_dedup) {
3430       G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3431     }
3432   }
3433 
3434   size_t strings_processed() const { return (size_t)_strings_processed; }
3435   size_t strings_removed()   const { return (size_t)_strings_removed; }
3436 
3437   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3438   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3439 };
3440 
3441 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3442 private:
3443   static Monitor* _lock;
3444 
3445   BoolObjectClosure* const _is_alive;
3446   const bool               _unloading_occurred;
3447   const uint               _num_workers;
3448 
3449   // Variables used to claim nmethods.
3450   CompiledMethod* _first_nmethod;
3451   volatile CompiledMethod* _claimed_nmethod;
3452 
3453   // The list of nmethods that need to be processed by the second pass.
3454   volatile CompiledMethod* _postponed_list;
3455   volatile uint            _num_entered_barrier;
3456 
3457  public:
3458   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3459       _is_alive(is_alive),
3460       _unloading_occurred(unloading_occurred),
3461       _num_workers(num_workers),
3462       _first_nmethod(NULL),
3463       _claimed_nmethod(NULL),
3464       _postponed_list(NULL),
3465       _num_entered_barrier(0)
3466   {
3467     CompiledMethod::increase_unloading_clock();
3468     // Get first alive nmethod
3469     CompiledMethodIterator iter = CompiledMethodIterator();
3470     if(iter.next_alive()) {
3471       _first_nmethod = iter.method();
3472     }
3473     _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3474   }
3475 
3476   ~G1CodeCacheUnloadingTask() {
3477     CodeCache::verify_clean_inline_caches();
3478 
3479     CodeCache::set_needs_cache_clean(false);
3480     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3481 
3482     CodeCache::verify_icholder_relocations();
3483   }
3484 
3485  private:
3486   void add_to_postponed_list(CompiledMethod* nm) {
3487       CompiledMethod* old;
3488       do {
3489         old = (CompiledMethod*)_postponed_list;
3490         nm->set_unloading_next(old);
3491       } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3492   }
3493 
3494   void clean_nmethod(CompiledMethod* nm) {
3495     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3496 
3497     if (postponed) {
3498       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3499       add_to_postponed_list(nm);
3500     }
3501 
3502     // Mark that this thread has been cleaned/unloaded.
3503     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3504     nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3505   }
3506 
3507   void clean_nmethod_postponed(CompiledMethod* nm) {
3508     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3509   }
3510 
3511   static const int MaxClaimNmethods = 16;
3512 
3513   void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3514     CompiledMethod* first;
3515     CompiledMethodIterator last;
3516 
3517     do {
3518       *num_claimed_nmethods = 0;
3519 
3520       first = (CompiledMethod*)_claimed_nmethod;
3521       last = CompiledMethodIterator(first);
3522 
3523       if (first != NULL) {
3524 
3525         for (int i = 0; i < MaxClaimNmethods; i++) {
3526           if (!last.next_alive()) {
3527             break;
3528           }
3529           claimed_nmethods[i] = last.method();
3530           (*num_claimed_nmethods)++;
3531         }
3532       }
3533 
3534     } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3535   }
3536 
3537   CompiledMethod* claim_postponed_nmethod() {
3538     CompiledMethod* claim;
3539     CompiledMethod* next;
3540 
3541     do {
3542       claim = (CompiledMethod*)_postponed_list;
3543       if (claim == NULL) {
3544         return NULL;
3545       }
3546 
3547       next = claim->unloading_next();
3548 
3549     } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3550 
3551     return claim;
3552   }
3553 
3554  public:
3555   // Mark that we're done with the first pass of nmethod cleaning.
3556   void barrier_mark(uint worker_id) {
3557     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3558     _num_entered_barrier++;
3559     if (_num_entered_barrier == _num_workers) {
3560       ml.notify_all();
3561     }
3562   }
3563 
3564   // See if we have to wait for the other workers to
3565   // finish their first-pass nmethod cleaning work.
3566   void barrier_wait(uint worker_id) {
3567     if (_num_entered_barrier < _num_workers) {
3568       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3569       while (_num_entered_barrier < _num_workers) {
3570           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3571       }
3572     }
3573   }
3574 
3575   // Cleaning and unloading of nmethods. Some work has to be postponed
3576   // to the second pass, when we know which nmethods survive.
3577   void work_first_pass(uint worker_id) {
3578     // The first nmethods is claimed by the first worker.
3579     if (worker_id == 0 && _first_nmethod != NULL) {
3580       clean_nmethod(_first_nmethod);
3581       _first_nmethod = NULL;
3582     }
3583 
3584     int num_claimed_nmethods;
3585     CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3586 
3587     while (true) {
3588       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3589 
3590       if (num_claimed_nmethods == 0) {
3591         break;
3592       }
3593 
3594       for (int i = 0; i < num_claimed_nmethods; i++) {
3595         clean_nmethod(claimed_nmethods[i]);
3596       }
3597     }
3598   }
3599 
3600   void work_second_pass(uint worker_id) {
3601     CompiledMethod* nm;
3602     // Take care of postponed nmethods.
3603     while ((nm = claim_postponed_nmethod()) != NULL) {
3604       clean_nmethod_postponed(nm);
3605     }
3606   }
3607 };
3608 
3609 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3610 
3611 class G1KlassCleaningTask : public StackObj {
3612   BoolObjectClosure*                      _is_alive;
3613   volatile jint                           _clean_klass_tree_claimed;
3614   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3615 
3616  public:
3617   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3618       _is_alive(is_alive),
3619       _clean_klass_tree_claimed(0),
3620       _klass_iterator() {
3621   }
3622 
3623  private:
3624   bool claim_clean_klass_tree_task() {
3625     if (_clean_klass_tree_claimed) {
3626       return false;
3627     }
3628 
3629     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3630   }
3631 
3632   InstanceKlass* claim_next_klass() {
3633     Klass* klass;
3634     do {
3635       klass =_klass_iterator.next_klass();
3636     } while (klass != NULL && !klass->is_instance_klass());
3637 
3638     // this can be null so don't call InstanceKlass::cast
3639     return static_cast<InstanceKlass*>(klass);
3640   }
3641 
3642 public:
3643 
3644   void clean_klass(InstanceKlass* ik) {
3645     ik->clean_weak_instanceklass_links(_is_alive);
3646   }
3647 
3648   void work() {
3649     ResourceMark rm;
3650 
3651     // One worker will clean the subklass/sibling klass tree.
3652     if (claim_clean_klass_tree_task()) {
3653       Klass::clean_subklass_tree(_is_alive);
3654     }
3655 
3656     // All workers will help cleaning the classes,
3657     InstanceKlass* klass;
3658     while ((klass = claim_next_klass()) != NULL) {
3659       clean_klass(klass);
3660     }
3661   }
3662 };
3663 
3664 class G1ResolvedMethodCleaningTask : public StackObj {
3665   BoolObjectClosure* _is_alive;
3666   volatile jint      _resolved_method_task_claimed;
3667 public:
3668   G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3669       _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3670 
3671   bool claim_resolved_method_task() {
3672     if (_resolved_method_task_claimed) {
3673       return false;
3674     }
3675     return Atomic::cmpxchg(1, (jint*)&_resolved_method_task_claimed, 0) == 0;
3676   }
3677 
3678   // These aren't big, one thread can do it all.
3679   void work() {
3680     if (claim_resolved_method_task()) {
3681       ResolvedMethodTable::unlink(_is_alive);
3682     }
3683   }
3684 };
3685 
3686 
3687 // To minimize the remark pause times, the tasks below are done in parallel.
3688 class G1ParallelCleaningTask : public AbstractGangTask {
3689 private:
3690   G1StringAndSymbolCleaningTask _string_symbol_task;
3691   G1CodeCacheUnloadingTask      _code_cache_task;
3692   G1KlassCleaningTask           _klass_cleaning_task;
3693   G1ResolvedMethodCleaningTask  _resolved_method_cleaning_task;
3694 
3695 public:
3696   // The constructor is run in the VMThread.
3697   G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3698       AbstractGangTask("Parallel Cleaning"),
3699       _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3700       _code_cache_task(num_workers, is_alive, unloading_occurred),
3701       _klass_cleaning_task(is_alive),
3702       _resolved_method_cleaning_task(is_alive) {
3703   }
3704 
3705   // The parallel work done by all worker threads.
3706   void work(uint worker_id) {
3707     // Do first pass of code cache cleaning.
3708     _code_cache_task.work_first_pass(worker_id);
3709 
3710     // Let the threads mark that the first pass is done.
3711     _code_cache_task.barrier_mark(worker_id);
3712 
3713     // Clean the Strings and Symbols.
3714     _string_symbol_task.work(worker_id);
3715 
3716     // Clean unreferenced things in the ResolvedMethodTable
3717     _resolved_method_cleaning_task.work();
3718 
3719     // Wait for all workers to finish the first code cache cleaning pass.
3720     _code_cache_task.barrier_wait(worker_id);
3721 
3722     // Do the second code cache cleaning work, which realize on
3723     // the liveness information gathered during the first pass.
3724     _code_cache_task.work_second_pass(worker_id);
3725 
3726     // Clean all klasses that were not unloaded.
3727     _klass_cleaning_task.work();
3728   }
3729 };
3730 
3731 
3732 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3733                                         bool class_unloading_occurred) {
3734   uint n_workers = workers()->active_workers();
3735 
3736   G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3737   workers()->run_task(&g1_unlink_task);
3738 }
3739 
3740 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3741                                        bool process_strings,
3742                                        bool process_symbols,
3743                                        bool process_string_dedup) {
3744   if (!process_strings && !process_symbols && !process_string_dedup) {
3745     // Nothing to clean.
3746     return;
3747   }
3748 
3749   G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3750   workers()->run_task(&g1_unlink_task);
3751 
3752 }
3753 
3754 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3755  private:
3756   DirtyCardQueueSet* _queue;
3757   G1CollectedHeap* _g1h;
3758  public:
3759   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3760     _queue(queue), _g1h(g1h) { }
3761 
3762   virtual void work(uint worker_id) {
3763     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3764     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3765 
3766     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3767     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3768 
3769     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3770   }
3771 };
3772 
3773 void G1CollectedHeap::redirty_logged_cards() {
3774   double redirty_logged_cards_start = os::elapsedTime();
3775 
3776   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3777   dirty_card_queue_set().reset_for_par_iteration();
3778   workers()->run_task(&redirty_task);
3779 
3780   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3781   dcq.merge_bufferlists(&dirty_card_queue_set());
3782   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3783 
3784   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3785 }
3786 
3787 // Weak Reference Processing support
3788 
3789 // An always "is_alive" closure that is used to preserve referents.
3790 // If the object is non-null then it's alive.  Used in the preservation
3791 // of referent objects that are pointed to by reference objects
3792 // discovered by the CM ref processor.
3793 class G1AlwaysAliveClosure: public BoolObjectClosure {
3794   G1CollectedHeap* _g1;
3795 public:
3796   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3797   bool do_object_b(oop p) {
3798     if (p != NULL) {
3799       return true;
3800     }
3801     return false;
3802   }
3803 };
3804 
3805 bool G1STWIsAliveClosure::do_object_b(oop p) {
3806   // An object is reachable if it is outside the collection set,
3807   // or is inside and copied.
3808   return !_g1->is_in_cset(p) || p->is_forwarded();
3809 }
3810 
3811 // Non Copying Keep Alive closure
3812 class G1KeepAliveClosure: public OopClosure {
3813   G1CollectedHeap* _g1;
3814 public:
3815   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3816   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3817   void do_oop(oop* p) {
3818     oop obj = *p;
3819     assert(obj != NULL, "the caller should have filtered out NULL values");
3820 
3821     const InCSetState cset_state = _g1->in_cset_state(obj);
3822     if (!cset_state.is_in_cset_or_humongous()) {
3823       return;
3824     }
3825     if (cset_state.is_in_cset()) {
3826       assert( obj->is_forwarded(), "invariant" );
3827       *p = obj->forwardee();
3828     } else {
3829       assert(!obj->is_forwarded(), "invariant" );
3830       assert(cset_state.is_humongous(),
3831              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3832       _g1->set_humongous_is_live(obj);
3833     }
3834   }
3835 };
3836 
3837 // Copying Keep Alive closure - can be called from both
3838 // serial and parallel code as long as different worker
3839 // threads utilize different G1ParScanThreadState instances
3840 // and different queues.
3841 
3842 class G1CopyingKeepAliveClosure: public OopClosure {
3843   G1CollectedHeap*         _g1h;
3844   OopClosure*              _copy_non_heap_obj_cl;
3845   G1ParScanThreadState*    _par_scan_state;
3846 
3847 public:
3848   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3849                             OopClosure* non_heap_obj_cl,
3850                             G1ParScanThreadState* pss):
3851     _g1h(g1h),
3852     _copy_non_heap_obj_cl(non_heap_obj_cl),
3853     _par_scan_state(pss)
3854   {}
3855 
3856   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3857   virtual void do_oop(      oop* p) { do_oop_work(p); }
3858 
3859   template <class T> void do_oop_work(T* p) {
3860     oop obj = oopDesc::load_decode_heap_oop(p);
3861 
3862     if (_g1h->is_in_cset_or_humongous(obj)) {
3863       // If the referent object has been forwarded (either copied
3864       // to a new location or to itself in the event of an
3865       // evacuation failure) then we need to update the reference
3866       // field and, if both reference and referent are in the G1
3867       // heap, update the RSet for the referent.
3868       //
3869       // If the referent has not been forwarded then we have to keep
3870       // it alive by policy. Therefore we have copy the referent.
3871       //
3872       // If the reference field is in the G1 heap then we can push
3873       // on the PSS queue. When the queue is drained (after each
3874       // phase of reference processing) the object and it's followers
3875       // will be copied, the reference field set to point to the
3876       // new location, and the RSet updated. Otherwise we need to
3877       // use the the non-heap or metadata closures directly to copy
3878       // the referent object and update the pointer, while avoiding
3879       // updating the RSet.
3880 
3881       if (_g1h->is_in_g1_reserved(p)) {
3882         _par_scan_state->push_on_queue(p);
3883       } else {
3884         assert(!Metaspace::contains((const void*)p),
3885                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3886         _copy_non_heap_obj_cl->do_oop(p);
3887       }
3888     }
3889   }
3890 };
3891 
3892 // Serial drain queue closure. Called as the 'complete_gc'
3893 // closure for each discovered list in some of the
3894 // reference processing phases.
3895 
3896 class G1STWDrainQueueClosure: public VoidClosure {
3897 protected:
3898   G1CollectedHeap* _g1h;
3899   G1ParScanThreadState* _par_scan_state;
3900 
3901   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3902 
3903 public:
3904   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3905     _g1h(g1h),
3906     _par_scan_state(pss)
3907   { }
3908 
3909   void do_void() {
3910     G1ParScanThreadState* const pss = par_scan_state();
3911     pss->trim_queue();
3912   }
3913 };
3914 
3915 // Parallel Reference Processing closures
3916 
3917 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3918 // processing during G1 evacuation pauses.
3919 
3920 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3921 private:
3922   G1CollectedHeap*          _g1h;
3923   G1ParScanThreadStateSet*  _pss;
3924   RefToScanQueueSet*        _queues;
3925   WorkGang*                 _workers;
3926   uint                      _active_workers;
3927 
3928 public:
3929   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3930                            G1ParScanThreadStateSet* per_thread_states,
3931                            WorkGang* workers,
3932                            RefToScanQueueSet *task_queues,
3933                            uint n_workers) :
3934     _g1h(g1h),
3935     _pss(per_thread_states),
3936     _queues(task_queues),
3937     _workers(workers),
3938     _active_workers(n_workers)
3939   {
3940     g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3941   }
3942 
3943   // Executes the given task using concurrent marking worker threads.
3944   virtual void execute(ProcessTask& task);
3945   virtual void execute(EnqueueTask& task);
3946 };
3947 
3948 // Gang task for possibly parallel reference processing
3949 
3950 class G1STWRefProcTaskProxy: public AbstractGangTask {
3951   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3952   ProcessTask&     _proc_task;
3953   G1CollectedHeap* _g1h;
3954   G1ParScanThreadStateSet* _pss;
3955   RefToScanQueueSet* _task_queues;
3956   ParallelTaskTerminator* _terminator;
3957 
3958 public:
3959   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3960                         G1CollectedHeap* g1h,
3961                         G1ParScanThreadStateSet* per_thread_states,
3962                         RefToScanQueueSet *task_queues,
3963                         ParallelTaskTerminator* terminator) :
3964     AbstractGangTask("Process reference objects in parallel"),
3965     _proc_task(proc_task),
3966     _g1h(g1h),
3967     _pss(per_thread_states),
3968     _task_queues(task_queues),
3969     _terminator(terminator)
3970   {}
3971 
3972   virtual void work(uint worker_id) {
3973     // The reference processing task executed by a single worker.
3974     ResourceMark rm;
3975     HandleMark   hm;
3976 
3977     G1STWIsAliveClosure is_alive(_g1h);
3978 
3979     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
3980     pss->set_ref_processor(NULL);
3981 
3982     // Keep alive closure.
3983     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3984 
3985     // Complete GC closure
3986     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3987 
3988     // Call the reference processing task's work routine.
3989     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3990 
3991     // Note we cannot assert that the refs array is empty here as not all
3992     // of the processing tasks (specifically phase2 - pp2_work) execute
3993     // the complete_gc closure (which ordinarily would drain the queue) so
3994     // the queue may not be empty.
3995   }
3996 };
3997 
3998 // Driver routine for parallel reference processing.
3999 // Creates an instance of the ref processing gang
4000 // task and has the worker threads execute it.
4001 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4002   assert(_workers != NULL, "Need parallel worker threads.");
4003 
4004   ParallelTaskTerminator terminator(_active_workers, _queues);
4005   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4006 
4007   _workers->run_task(&proc_task_proxy);
4008 }
4009 
4010 // Gang task for parallel reference enqueueing.
4011 
4012 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4013   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4014   EnqueueTask& _enq_task;
4015 
4016 public:
4017   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4018     AbstractGangTask("Enqueue reference objects in parallel"),
4019     _enq_task(enq_task)
4020   { }
4021 
4022   virtual void work(uint worker_id) {
4023     _enq_task.work(worker_id);
4024   }
4025 };
4026 
4027 // Driver routine for parallel reference enqueueing.
4028 // Creates an instance of the ref enqueueing gang
4029 // task and has the worker threads execute it.
4030 
4031 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4032   assert(_workers != NULL, "Need parallel worker threads.");
4033 
4034   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4035 
4036   _workers->run_task(&enq_task_proxy);
4037 }
4038 
4039 // End of weak reference support closures
4040 
4041 // Abstract task used to preserve (i.e. copy) any referent objects
4042 // that are in the collection set and are pointed to by reference
4043 // objects discovered by the CM ref processor.
4044 
4045 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4046 protected:
4047   G1CollectedHeap*         _g1h;
4048   G1ParScanThreadStateSet* _pss;
4049   RefToScanQueueSet*       _queues;
4050   ParallelTaskTerminator   _terminator;
4051   uint                     _n_workers;
4052 
4053 public:
4054   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4055     AbstractGangTask("ParPreserveCMReferents"),
4056     _g1h(g1h),
4057     _pss(per_thread_states),
4058     _queues(task_queues),
4059     _terminator(workers, _queues),
4060     _n_workers(workers)
4061   {
4062     g1h->ref_processor_cm()->set_active_mt_degree(workers);
4063   }
4064 
4065   void work(uint worker_id) {
4066     G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4067 
4068     ResourceMark rm;
4069     HandleMark   hm;
4070 
4071     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4072     pss->set_ref_processor(NULL);
4073     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4074 
4075     // Is alive closure
4076     G1AlwaysAliveClosure always_alive(_g1h);
4077 
4078     // Copying keep alive closure. Applied to referent objects that need
4079     // to be copied.
4080     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4081 
4082     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4083 
4084     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4085     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4086 
4087     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4088     // So this must be true - but assert just in case someone decides to
4089     // change the worker ids.
4090     assert(worker_id < limit, "sanity");
4091     assert(!rp->discovery_is_atomic(), "check this code");
4092 
4093     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4094     for (uint idx = worker_id; idx < limit; idx += stride) {
4095       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4096 
4097       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4098       while (iter.has_next()) {
4099         // Since discovery is not atomic for the CM ref processor, we
4100         // can see some null referent objects.
4101         iter.load_ptrs(DEBUG_ONLY(true));
4102         oop ref = iter.obj();
4103 
4104         // This will filter nulls.
4105         if (iter.is_referent_alive()) {
4106           iter.make_referent_alive();
4107         }
4108         iter.move_to_next();
4109       }
4110     }
4111 
4112     // Drain the queue - which may cause stealing
4113     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4114     drain_queue.do_void();
4115     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4116     assert(pss->queue_is_empty(), "should be");
4117   }
4118 };
4119 
4120 void G1CollectedHeap::process_weak_jni_handles() {
4121   double ref_proc_start = os::elapsedTime();
4122 
4123   G1STWIsAliveClosure is_alive(this);
4124   G1KeepAliveClosure keep_alive(this);
4125   JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4126 
4127   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4128   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4129 }
4130 
4131 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4132   // Any reference objects, in the collection set, that were 'discovered'
4133   // by the CM ref processor should have already been copied (either by
4134   // applying the external root copy closure to the discovered lists, or
4135   // by following an RSet entry).
4136   //
4137   // But some of the referents, that are in the collection set, that these
4138   // reference objects point to may not have been copied: the STW ref
4139   // processor would have seen that the reference object had already
4140   // been 'discovered' and would have skipped discovering the reference,
4141   // but would not have treated the reference object as a regular oop.
4142   // As a result the copy closure would not have been applied to the
4143   // referent object.
4144   //
4145   // We need to explicitly copy these referent objects - the references
4146   // will be processed at the end of remarking.
4147   //
4148   // We also need to do this copying before we process the reference
4149   // objects discovered by the STW ref processor in case one of these
4150   // referents points to another object which is also referenced by an
4151   // object discovered by the STW ref processor.
4152   double preserve_cm_referents_time = 0.0;
4153 
4154   // To avoid spawning task when there is no work to do, check that
4155   // a concurrent cycle is active and that some references have been
4156   // discovered.
4157   if (concurrent_mark()->cmThread()->during_cycle() &&
4158       ref_processor_cm()->has_discovered_references()) {
4159     double preserve_cm_referents_start = os::elapsedTime();
4160     uint no_of_gc_workers = workers()->active_workers();
4161     G1ParPreserveCMReferentsTask keep_cm_referents(this,
4162                                                    per_thread_states,
4163                                                    no_of_gc_workers,
4164                                                    _task_queues);
4165     workers()->run_task(&keep_cm_referents);
4166     preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4167   }
4168 
4169   g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4170 }
4171 
4172 // Weak Reference processing during an evacuation pause (part 1).
4173 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4174   double ref_proc_start = os::elapsedTime();
4175 
4176   ReferenceProcessor* rp = _ref_processor_stw;
4177   assert(rp->discovery_enabled(), "should have been enabled");
4178 
4179   // Closure to test whether a referent is alive.
4180   G1STWIsAliveClosure is_alive(this);
4181 
4182   // Even when parallel reference processing is enabled, the processing
4183   // of JNI refs is serial and performed serially by the current thread
4184   // rather than by a worker. The following PSS will be used for processing
4185   // JNI refs.
4186 
4187   // Use only a single queue for this PSS.
4188   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4189   pss->set_ref_processor(NULL);
4190   assert(pss->queue_is_empty(), "pre-condition");
4191 
4192   // Keep alive closure.
4193   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4194 
4195   // Serial Complete GC closure
4196   G1STWDrainQueueClosure drain_queue(this, pss);
4197 
4198   // Setup the soft refs policy...
4199   rp->setup_policy(false);
4200 
4201   ReferenceProcessorStats stats;
4202   if (!rp->processing_is_mt()) {
4203     // Serial reference processing...
4204     stats = rp->process_discovered_references(&is_alive,
4205                                               &keep_alive,
4206                                               &drain_queue,
4207                                               NULL,
4208                                               _gc_timer_stw);
4209   } else {
4210     uint no_of_gc_workers = workers()->active_workers();
4211 
4212     // Parallel reference processing
4213     assert(no_of_gc_workers <= rp->max_num_q(),
4214            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4215            no_of_gc_workers,  rp->max_num_q());
4216 
4217     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4218     stats = rp->process_discovered_references(&is_alive,
4219                                               &keep_alive,
4220                                               &drain_queue,
4221                                               &par_task_executor,
4222                                               _gc_timer_stw);
4223   }
4224 
4225   _gc_tracer_stw->report_gc_reference_stats(stats);
4226 
4227   // We have completed copying any necessary live referent objects.
4228   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4229 
4230   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4231   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4232 }
4233 
4234 // Weak Reference processing during an evacuation pause (part 2).
4235 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4236   double ref_enq_start = os::elapsedTime();
4237 
4238   ReferenceProcessor* rp = _ref_processor_stw;
4239   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4240 
4241   // Now enqueue any remaining on the discovered lists on to
4242   // the pending list.
4243   if (!rp->processing_is_mt()) {
4244     // Serial reference processing...
4245     rp->enqueue_discovered_references();
4246   } else {
4247     // Parallel reference enqueueing
4248 
4249     uint n_workers = workers()->active_workers();
4250 
4251     assert(n_workers <= rp->max_num_q(),
4252            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4253            n_workers,  rp->max_num_q());
4254 
4255     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4256     rp->enqueue_discovered_references(&par_task_executor);
4257   }
4258 
4259   rp->verify_no_references_recorded();
4260   assert(!rp->discovery_enabled(), "should have been disabled");
4261 
4262   // FIXME
4263   // CM's reference processing also cleans up the string and symbol tables.
4264   // Should we do that here also? We could, but it is a serial operation
4265   // and could significantly increase the pause time.
4266 
4267   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4268   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4269 }
4270 
4271 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4272   double merge_pss_time_start = os::elapsedTime();
4273   per_thread_states->flush();
4274   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4275 }
4276 
4277 void G1CollectedHeap::pre_evacuate_collection_set() {
4278   _expand_heap_after_alloc_failure = true;
4279   _evacuation_failed = false;
4280 
4281   // Disable the hot card cache.
4282   _hot_card_cache->reset_hot_cache_claimed_index();
4283   _hot_card_cache->set_use_cache(false);
4284 
4285   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4286   _preserved_marks_set.assert_empty();
4287 
4288   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4289 
4290   // InitialMark needs claim bits to keep track of the marked-through CLDs.
4291   if (collector_state()->during_initial_mark_pause()) {
4292     double start_clear_claimed_marks = os::elapsedTime();
4293 
4294     ClassLoaderDataGraph::clear_claimed_marks();
4295 
4296     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4297     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4298   }
4299 }
4300 
4301 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4302   // Should G1EvacuationFailureALot be in effect for this GC?
4303   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4304 
4305   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4306 
4307   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4308 
4309   double start_par_time_sec = os::elapsedTime();
4310   double end_par_time_sec;
4311 
4312   {
4313     const uint n_workers = workers()->active_workers();
4314     G1RootProcessor root_processor(this, n_workers);
4315     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4316 
4317     print_termination_stats_hdr();
4318 
4319     workers()->run_task(&g1_par_task);
4320     end_par_time_sec = os::elapsedTime();
4321 
4322     // Closing the inner scope will execute the destructor
4323     // for the G1RootProcessor object. We record the current
4324     // elapsed time before closing the scope so that time
4325     // taken for the destructor is NOT included in the
4326     // reported parallel time.
4327   }
4328 
4329   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4330   phase_times->record_par_time(par_time_ms);
4331 
4332   double code_root_fixup_time_ms =
4333         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4334   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4335 }
4336 
4337 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4338   // Process any discovered reference objects - we have
4339   // to do this _before_ we retire the GC alloc regions
4340   // as we may have to copy some 'reachable' referent
4341   // objects (and their reachable sub-graphs) that were
4342   // not copied during the pause.
4343   if (g1_policy()->should_process_references()) {
4344     preserve_cm_referents(per_thread_states);
4345     process_discovered_references(per_thread_states);
4346   } else {
4347     ref_processor_stw()->verify_no_references_recorded();
4348     process_weak_jni_handles();
4349   }
4350 
4351   if (G1StringDedup::is_enabled()) {
4352     double fixup_start = os::elapsedTime();
4353 
4354     G1STWIsAliveClosure is_alive(this);
4355     G1KeepAliveClosure keep_alive(this);
4356     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4357 
4358     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4359     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4360   }
4361 
4362   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4363 
4364   if (evacuation_failed()) {
4365     restore_after_evac_failure();
4366 
4367     // Reset the G1EvacuationFailureALot counters and flags
4368     // Note: the values are reset only when an actual
4369     // evacuation failure occurs.
4370     NOT_PRODUCT(reset_evacuation_should_fail();)
4371   }
4372 
4373   _preserved_marks_set.assert_empty();
4374 
4375   // Enqueue any remaining references remaining on the STW
4376   // reference processor's discovered lists. We need to do
4377   // this after the card table is cleaned (and verified) as
4378   // the act of enqueueing entries on to the pending list
4379   // will log these updates (and dirty their associated
4380   // cards). We need these updates logged to update any
4381   // RSets.
4382   if (g1_policy()->should_process_references()) {
4383     enqueue_discovered_references(per_thread_states);
4384   } else {
4385     g1_policy()->phase_times()->record_ref_enq_time(0);
4386   }
4387 
4388   _allocator->release_gc_alloc_regions(evacuation_info);
4389 
4390   merge_per_thread_state_info(per_thread_states);
4391 
4392   // Reset and re-enable the hot card cache.
4393   // Note the counts for the cards in the regions in the
4394   // collection set are reset when the collection set is freed.
4395   _hot_card_cache->reset_hot_cache();
4396   _hot_card_cache->set_use_cache(true);
4397 
4398   purge_code_root_memory();
4399 
4400   redirty_logged_cards();
4401 #if defined(COMPILER2) || INCLUDE_JVMCI
4402   double start = os::elapsedTime();
4403   DerivedPointerTable::update_pointers();
4404   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4405 #endif
4406   g1_policy()->print_age_table();
4407 }
4408 
4409 void G1CollectedHeap::record_obj_copy_mem_stats() {
4410   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4411 
4412   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4413                                                create_g1_evac_summary(&_old_evac_stats));
4414 }
4415 
4416 void G1CollectedHeap::free_region(HeapRegion* hr,
4417                                   FreeRegionList* free_list,
4418                                   bool skip_remset,
4419                                   bool skip_hot_card_cache,
4420                                   bool locked) {
4421   assert(!hr->is_free(), "the region should not be free");
4422   assert(!hr->is_empty(), "the region should not be empty");
4423   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4424   assert(free_list != NULL, "pre-condition");
4425 
4426   if (G1VerifyBitmaps) {
4427     MemRegion mr(hr->bottom(), hr->end());
4428     concurrent_mark()->clearRangePrevBitmap(mr);
4429   }
4430 
4431   // Clear the card counts for this region.
4432   // Note: we only need to do this if the region is not young
4433   // (since we don't refine cards in young regions).
4434   if (!skip_hot_card_cache && !hr->is_young()) {
4435     _hot_card_cache->reset_card_counts(hr);
4436   }
4437   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4438   free_list->add_ordered(hr);
4439 }
4440 
4441 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4442                                             FreeRegionList* free_list,
4443                                             bool skip_remset) {
4444   assert(hr->is_humongous(), "this is only for humongous regions");
4445   assert(free_list != NULL, "pre-condition");
4446   hr->clear_humongous();
4447   free_region(hr, free_list, skip_remset);
4448 }
4449 
4450 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4451                                            const uint humongous_regions_removed) {
4452   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4453     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4454     _old_set.bulk_remove(old_regions_removed);
4455     _humongous_set.bulk_remove(humongous_regions_removed);
4456   }
4457 
4458 }
4459 
4460 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4461   assert(list != NULL, "list can't be null");
4462   if (!list->is_empty()) {
4463     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4464     _hrm.insert_list_into_free_list(list);
4465   }
4466 }
4467 
4468 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4469   decrease_used(bytes);
4470 }
4471 
4472 class G1ParScrubRemSetTask: public AbstractGangTask {
4473 protected:
4474   G1RemSet* _g1rs;
4475   HeapRegionClaimer _hrclaimer;
4476 
4477 public:
4478   G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4479     AbstractGangTask("G1 ScrubRS"),
4480     _g1rs(g1_rs),
4481     _hrclaimer(num_workers) {
4482   }
4483 
4484   void work(uint worker_id) {
4485     _g1rs->scrub(worker_id, &_hrclaimer);
4486   }
4487 };
4488 
4489 void G1CollectedHeap::scrub_rem_set() {
4490   uint num_workers = workers()->active_workers();
4491   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4492   workers()->run_task(&g1_par_scrub_rs_task);
4493 }
4494 
4495 class G1FreeCollectionSetTask : public AbstractGangTask {
4496 private:
4497 
4498   // Closure applied to all regions in the collection set to do work that needs to
4499   // be done serially in a single thread.
4500   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4501   private:
4502     EvacuationInfo* _evacuation_info;
4503     const size_t* _surviving_young_words;
4504 
4505     // Bytes used in successfully evacuated regions before the evacuation.
4506     size_t _before_used_bytes;
4507     // Bytes used in unsucessfully evacuated regions before the evacuation
4508     size_t _after_used_bytes;
4509 
4510     size_t _bytes_allocated_in_old_since_last_gc;
4511 
4512     size_t _failure_used_words;
4513     size_t _failure_waste_words;
4514 
4515     FreeRegionList _local_free_list;
4516   public:
4517     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4518       HeapRegionClosure(),
4519       _evacuation_info(evacuation_info),
4520       _surviving_young_words(surviving_young_words),
4521       _before_used_bytes(0),
4522       _after_used_bytes(0),
4523       _bytes_allocated_in_old_since_last_gc(0),
4524       _failure_used_words(0),
4525       _failure_waste_words(0),
4526       _local_free_list("Local Region List for CSet Freeing") {
4527     }
4528 
4529     virtual bool doHeapRegion(HeapRegion* r) {
4530       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4531 
4532       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4533       g1h->clear_in_cset(r);
4534 
4535       if (r->is_young()) {
4536         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4537                "Young index %d is wrong for region %u of type %s with %u young regions",
4538                r->young_index_in_cset(),
4539                r->hrm_index(),
4540                r->get_type_str(),
4541                g1h->collection_set()->young_region_length());
4542         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4543         r->record_surv_words_in_group(words_survived);
4544       }
4545 
4546       if (!r->evacuation_failed()) {
4547         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4548         _before_used_bytes += r->used();
4549         g1h->free_region(r,
4550                          &_local_free_list,
4551                          true, /* skip_remset */
4552                          true, /* skip_hot_card_cache */
4553                          true  /* locked */);
4554       } else {
4555         r->uninstall_surv_rate_group();
4556         r->set_young_index_in_cset(-1);
4557         r->set_evacuation_failed(false);
4558         // When moving a young gen region to old gen, we "allocate" that whole region
4559         // there. This is in addition to any already evacuated objects. Notify the
4560         // policy about that.
4561         // Old gen regions do not cause an additional allocation: both the objects
4562         // still in the region and the ones already moved are accounted for elsewhere.
4563         if (r->is_young()) {
4564           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4565         }
4566         // The region is now considered to be old.
4567         r->set_old();
4568         // Do some allocation statistics accounting. Regions that failed evacuation
4569         // are always made old, so there is no need to update anything in the young
4570         // gen statistics, but we need to update old gen statistics.
4571         size_t used_words = r->marked_bytes() / HeapWordSize;
4572 
4573         _failure_used_words += used_words;
4574         _failure_waste_words += HeapRegion::GrainWords - used_words;
4575 
4576         g1h->old_set_add(r);
4577         _after_used_bytes += r->used();
4578       }
4579       return false;
4580     }
4581 
4582     void complete_work() {
4583       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4584 
4585       _evacuation_info->set_regions_freed(_local_free_list.length());
4586       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4587 
4588       g1h->prepend_to_freelist(&_local_free_list);
4589       g1h->decrement_summary_bytes(_before_used_bytes);
4590 
4591       G1Policy* policy = g1h->g1_policy();
4592       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4593 
4594       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4595     }
4596   };
4597 
4598   G1CollectionSet* _collection_set;
4599   G1SerialFreeCollectionSetClosure _cl;
4600   const size_t* _surviving_young_words;
4601 
4602   size_t _rs_lengths;
4603 
4604   volatile jint _serial_work_claim;
4605 
4606   struct WorkItem {
4607     uint region_idx;
4608     bool is_young;
4609     bool evacuation_failed;
4610 
4611     WorkItem(HeapRegion* r) {
4612       region_idx = r->hrm_index();
4613       is_young = r->is_young();
4614       evacuation_failed = r->evacuation_failed();
4615     }
4616   };
4617 
4618   volatile size_t _parallel_work_claim;
4619   size_t _num_work_items;
4620   WorkItem* _work_items;
4621 
4622   void do_serial_work() {
4623     // Need to grab the lock to be allowed to modify the old region list.
4624     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4625     _collection_set->iterate(&_cl);
4626   }
4627 
4628   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4629     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4630 
4631     HeapRegion* r = g1h->region_at(region_idx);
4632     assert(!g1h->is_on_master_free_list(r), "sanity");
4633 
4634     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4635 
4636     if (!is_young) {
4637       g1h->_hot_card_cache->reset_card_counts(r);
4638     }
4639 
4640     if (!evacuation_failed) {
4641       r->rem_set()->clear_locked();
4642     }
4643   }
4644 
4645   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4646   private:
4647     size_t _cur_idx;
4648     WorkItem* _work_items;
4649   public:
4650     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4651 
4652     virtual bool doHeapRegion(HeapRegion* r) {
4653       _work_items[_cur_idx++] = WorkItem(r);
4654       return false;
4655     }
4656   };
4657 
4658   void prepare_work() {
4659     G1PrepareFreeCollectionSetClosure cl(_work_items);
4660     _collection_set->iterate(&cl);
4661   }
4662 
4663   void complete_work() {
4664     _cl.complete_work();
4665 
4666     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4667     policy->record_max_rs_lengths(_rs_lengths);
4668     policy->cset_regions_freed();
4669   }
4670 public:
4671   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4672     AbstractGangTask("G1 Free Collection Set"),
4673     _cl(evacuation_info, surviving_young_words),
4674     _collection_set(collection_set),
4675     _surviving_young_words(surviving_young_words),
4676     _serial_work_claim(0),
4677     _rs_lengths(0),
4678     _parallel_work_claim(0),
4679     _num_work_items(collection_set->region_length()),
4680     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4681     prepare_work();
4682   }
4683 
4684   ~G1FreeCollectionSetTask() {
4685     complete_work();
4686     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4687   }
4688 
4689   // Chunk size for work distribution. The chosen value has been determined experimentally
4690   // to be a good tradeoff between overhead and achievable parallelism.
4691   static uint chunk_size() { return 32; }
4692 
4693   virtual void work(uint worker_id) {
4694     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4695 
4696     // Claim serial work.
4697     if (_serial_work_claim == 0) {
4698       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4699       if (value == 0) {
4700         double serial_time = os::elapsedTime();
4701         do_serial_work();
4702         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4703       }
4704     }
4705 
4706     // Start parallel work.
4707     double young_time = 0.0;
4708     bool has_young_time = false;
4709     double non_young_time = 0.0;
4710     bool has_non_young_time = false;
4711 
4712     while (true) {
4713       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4714       size_t cur = end - chunk_size();
4715 
4716       if (cur >= _num_work_items) {
4717         break;
4718       }
4719 
4720       double start_time = os::elapsedTime();
4721 
4722       end = MIN2(end, _num_work_items);
4723 
4724       for (; cur < end; cur++) {
4725         bool is_young = _work_items[cur].is_young;
4726 
4727         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4728 
4729         double end_time = os::elapsedTime();
4730         double time_taken = end_time - start_time;
4731         if (is_young) {
4732           young_time += time_taken;
4733           has_young_time = true;
4734         } else {
4735           non_young_time += time_taken;
4736           has_non_young_time = true;
4737         }
4738         start_time = end_time;
4739       }
4740     }
4741 
4742     if (has_young_time) {
4743       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4744     }
4745     if (has_non_young_time) {
4746       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4747     }
4748   }
4749 };
4750 
4751 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4752   _eden.clear();
4753 
4754   double free_cset_start_time = os::elapsedTime();
4755 
4756   {
4757     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4758     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4759 
4760     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4761 
4762     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4763                         cl.name(),
4764                         num_workers,
4765                         _collection_set.region_length());
4766     workers()->run_task(&cl, num_workers);
4767   }
4768   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4769 
4770   collection_set->clear();
4771 }
4772 
4773 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4774  private:
4775   FreeRegionList* _free_region_list;
4776   HeapRegionSet* _proxy_set;
4777   uint _humongous_objects_reclaimed;
4778   uint _humongous_regions_reclaimed;
4779   size_t _freed_bytes;
4780  public:
4781 
4782   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4783     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4784   }
4785 
4786   virtual bool doHeapRegion(HeapRegion* r) {
4787     if (!r->is_starts_humongous()) {
4788       return false;
4789     }
4790 
4791     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4792 
4793     oop obj = (oop)r->bottom();
4794     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4795 
4796     // The following checks whether the humongous object is live are sufficient.
4797     // The main additional check (in addition to having a reference from the roots
4798     // or the young gen) is whether the humongous object has a remembered set entry.
4799     //
4800     // A humongous object cannot be live if there is no remembered set for it
4801     // because:
4802     // - there can be no references from within humongous starts regions referencing
4803     // the object because we never allocate other objects into them.
4804     // (I.e. there are no intra-region references that may be missed by the
4805     // remembered set)
4806     // - as soon there is a remembered set entry to the humongous starts region
4807     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4808     // until the end of a concurrent mark.
4809     //
4810     // It is not required to check whether the object has been found dead by marking
4811     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4812     // all objects allocated during that time are considered live.
4813     // SATB marking is even more conservative than the remembered set.
4814     // So if at this point in the collection there is no remembered set entry,
4815     // nobody has a reference to it.
4816     // At the start of collection we flush all refinement logs, and remembered sets
4817     // are completely up-to-date wrt to references to the humongous object.
4818     //
4819     // Other implementation considerations:
4820     // - never consider object arrays at this time because they would pose
4821     // considerable effort for cleaning up the the remembered sets. This is
4822     // required because stale remembered sets might reference locations that
4823     // are currently allocated into.
4824     uint region_idx = r->hrm_index();
4825     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4826         !r->rem_set()->is_empty()) {
4827       log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT "  with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
4828                                region_idx,
4829                                (size_t)obj->size() * HeapWordSize,
4830                                p2i(r->bottom()),
4831                                r->rem_set()->occupied(),
4832                                r->rem_set()->strong_code_roots_list_length(),
4833                                next_bitmap->isMarked(r->bottom()),
4834                                g1h->is_humongous_reclaim_candidate(region_idx),
4835                                obj->is_typeArray()
4836                               );
4837       return false;
4838     }
4839 
4840     guarantee(obj->is_typeArray(),
4841               "Only eagerly reclaiming type arrays is supported, but the object "
4842               PTR_FORMAT " is not.", p2i(r->bottom()));
4843 
4844     log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
4845                              region_idx,
4846                              (size_t)obj->size() * HeapWordSize,
4847                              p2i(r->bottom()),
4848                              r->rem_set()->occupied(),
4849                              r->rem_set()->strong_code_roots_list_length(),
4850                              next_bitmap->isMarked(r->bottom()),
4851                              g1h->is_humongous_reclaim_candidate(region_idx),
4852                              obj->is_typeArray()
4853                             );
4854 
4855     // Need to clear mark bit of the humongous object if already set.
4856     if (next_bitmap->isMarked(r->bottom())) {
4857       next_bitmap->clear(r->bottom());
4858     }
4859     _humongous_objects_reclaimed++;
4860     do {
4861       HeapRegion* next = g1h->next_region_in_humongous(r);
4862       _freed_bytes += r->used();
4863       r->set_containing_set(NULL);
4864       _humongous_regions_reclaimed++;
4865       g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4866       r = next;
4867     } while (r != NULL);
4868 
4869     return false;
4870   }
4871 
4872   uint humongous_objects_reclaimed() {
4873     return _humongous_objects_reclaimed;
4874   }
4875 
4876   uint humongous_regions_reclaimed() {
4877     return _humongous_regions_reclaimed;
4878   }
4879 
4880   size_t bytes_freed() const {
4881     return _freed_bytes;
4882   }
4883 };
4884 
4885 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4886   assert_at_safepoint(true);
4887 
4888   if (!G1EagerReclaimHumongousObjects ||
4889       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4890     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4891     return;
4892   }
4893 
4894   double start_time = os::elapsedTime();
4895 
4896   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4897 
4898   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4899   heap_region_iterate(&cl);
4900 
4901   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4902 
4903   G1HRPrinter* hrp = hr_printer();
4904   if (hrp->is_active()) {
4905     FreeRegionListIterator iter(&local_cleanup_list);
4906     while (iter.more_available()) {
4907       HeapRegion* hr = iter.get_next();
4908       hrp->cleanup(hr);
4909     }
4910   }
4911 
4912   prepend_to_freelist(&local_cleanup_list);
4913   decrement_summary_bytes(cl.bytes_freed());
4914 
4915   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4916                                                                     cl.humongous_objects_reclaimed());
4917 }
4918 
4919 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4920 public:
4921   virtual bool doHeapRegion(HeapRegion* r) {
4922     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4923     G1CollectedHeap::heap()->clear_in_cset(r);
4924     r->set_young_index_in_cset(-1);
4925     return false;
4926   }
4927 };
4928 
4929 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4930   G1AbandonCollectionSetClosure cl;
4931   collection_set->iterate(&cl);
4932 
4933   collection_set->clear();
4934   collection_set->stop_incremental_building();
4935 }
4936 
4937 void G1CollectedHeap::set_free_regions_coming() {
4938   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4939 
4940   assert(!free_regions_coming(), "pre-condition");
4941   _free_regions_coming = true;
4942 }
4943 
4944 void G1CollectedHeap::reset_free_regions_coming() {
4945   assert(free_regions_coming(), "pre-condition");
4946 
4947   {
4948     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4949     _free_regions_coming = false;
4950     SecondaryFreeList_lock->notify_all();
4951   }
4952 
4953   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4954 }
4955 
4956 void G1CollectedHeap::wait_while_free_regions_coming() {
4957   // Most of the time we won't have to wait, so let's do a quick test
4958   // first before we take the lock.
4959   if (!free_regions_coming()) {
4960     return;
4961   }
4962 
4963   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4964 
4965   {
4966     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4967     while (free_regions_coming()) {
4968       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4969     }
4970   }
4971 
4972   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
4973 }
4974 
4975 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4976   return _allocator->is_retained_old_region(hr);
4977 }
4978 
4979 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4980   _eden.add(hr);
4981   _g1_policy->set_region_eden(hr);
4982 }
4983 
4984 #ifdef ASSERT
4985 
4986 class NoYoungRegionsClosure: public HeapRegionClosure {
4987 private:
4988   bool _success;
4989 public:
4990   NoYoungRegionsClosure() : _success(true) { }
4991   bool doHeapRegion(HeapRegion* r) {
4992     if (r->is_young()) {
4993       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4994                             p2i(r->bottom()), p2i(r->end()));
4995       _success = false;
4996     }
4997     return false;
4998   }
4999   bool success() { return _success; }
5000 };
5001 
5002 bool G1CollectedHeap::check_young_list_empty() {
5003   bool ret = (young_regions_count() == 0);
5004 
5005   NoYoungRegionsClosure closure;
5006   heap_region_iterate(&closure);
5007   ret = ret && closure.success();
5008 
5009   return ret;
5010 }
5011 
5012 #endif // ASSERT
5013 
5014 class TearDownRegionSetsClosure : public HeapRegionClosure {
5015 private:
5016   HeapRegionSet *_old_set;
5017 
5018 public:
5019   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5020 
5021   bool doHeapRegion(HeapRegion* r) {
5022     if (r->is_old()) {
5023       _old_set->remove(r);
5024     } else if(r->is_young()) {
5025       r->uninstall_surv_rate_group();
5026     } else {
5027       // We ignore free regions, we'll empty the free list afterwards.
5028       // We ignore humongous regions, we're not tearing down the
5029       // humongous regions set.
5030       assert(r->is_free() || r->is_humongous(),
5031              "it cannot be another type");
5032     }
5033     return false;
5034   }
5035 
5036   ~TearDownRegionSetsClosure() {
5037     assert(_old_set->is_empty(), "post-condition");
5038   }
5039 };
5040 
5041 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5042   assert_at_safepoint(true /* should_be_vm_thread */);
5043 
5044   if (!free_list_only) {
5045     TearDownRegionSetsClosure cl(&_old_set);
5046     heap_region_iterate(&cl);
5047 
5048     // Note that emptying the _young_list is postponed and instead done as
5049     // the first step when rebuilding the regions sets again. The reason for
5050     // this is that during a full GC string deduplication needs to know if
5051     // a collected region was young or old when the full GC was initiated.
5052   }
5053   _hrm.remove_all_free_regions();
5054 }
5055 
5056 void G1CollectedHeap::increase_used(size_t bytes) {
5057   _summary_bytes_used += bytes;
5058 }
5059 
5060 void G1CollectedHeap::decrease_used(size_t bytes) {
5061   assert(_summary_bytes_used >= bytes,
5062          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5063          _summary_bytes_used, bytes);
5064   _summary_bytes_used -= bytes;
5065 }
5066 
5067 void G1CollectedHeap::set_used(size_t bytes) {
5068   _summary_bytes_used = bytes;
5069 }
5070 
5071 class RebuildRegionSetsClosure : public HeapRegionClosure {
5072 private:
5073   bool            _free_list_only;
5074   HeapRegionSet*   _old_set;
5075   HeapRegionManager*   _hrm;
5076   size_t          _total_used;
5077 
5078 public:
5079   RebuildRegionSetsClosure(bool free_list_only,
5080                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5081     _free_list_only(free_list_only),
5082     _old_set(old_set), _hrm(hrm), _total_used(0) {
5083     assert(_hrm->num_free_regions() == 0, "pre-condition");
5084     if (!free_list_only) {
5085       assert(_old_set->is_empty(), "pre-condition");
5086     }
5087   }
5088 
5089   bool doHeapRegion(HeapRegion* r) {
5090     if (r->is_empty()) {
5091       // Add free regions to the free list
5092       r->set_free();
5093       r->set_allocation_context(AllocationContext::system());
5094       _hrm->insert_into_free_list(r);
5095     } else if (!_free_list_only) {
5096 
5097       if (r->is_humongous()) {
5098         // We ignore humongous regions. We left the humongous set unchanged.
5099       } else {
5100         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5101         // We now consider all regions old, so register as such. Leave
5102         // archive regions set that way, however, while still adding
5103         // them to the old set.
5104         if (!r->is_archive()) {
5105           r->set_old();
5106         }
5107         _old_set->add(r);
5108       }
5109       _total_used += r->used();
5110     }
5111 
5112     return false;
5113   }
5114 
5115   size_t total_used() {
5116     return _total_used;
5117   }
5118 };
5119 
5120 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5121   assert_at_safepoint(true /* should_be_vm_thread */);
5122 
5123   if (!free_list_only) {
5124     _eden.clear();
5125     _survivor.clear();
5126   }
5127 
5128   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5129   heap_region_iterate(&cl);
5130 
5131   if (!free_list_only) {
5132     set_used(cl.total_used());
5133     if (_archive_allocator != NULL) {
5134       _archive_allocator->clear_used();
5135     }
5136   }
5137   assert(used_unlocked() == recalculate_used(),
5138          "inconsistent used_unlocked(), "
5139          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5140          used_unlocked(), recalculate_used());
5141 }
5142 
5143 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5144   HeapRegion* hr = heap_region_containing(p);
5145   return hr->is_in(p);
5146 }
5147 
5148 // Methods for the mutator alloc region
5149 
5150 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5151                                                       bool force) {
5152   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5153   bool should_allocate = g1_policy()->should_allocate_mutator_region();
5154   if (force || should_allocate) {
5155     HeapRegion* new_alloc_region = new_region(word_size,
5156                                               false /* is_old */,
5157                                               false /* do_expand */);
5158     if (new_alloc_region != NULL) {
5159       set_region_short_lived_locked(new_alloc_region);
5160       _hr_printer.alloc(new_alloc_region, !should_allocate);
5161       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5162       return new_alloc_region;
5163     }
5164   }
5165   return NULL;
5166 }
5167 
5168 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5169                                                   size_t allocated_bytes) {
5170   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5171   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5172 
5173   collection_set()->add_eden_region(alloc_region);
5174   increase_used(allocated_bytes);
5175   _hr_printer.retire(alloc_region);
5176   // We update the eden sizes here, when the region is retired,
5177   // instead of when it's allocated, since this is the point that its
5178   // used space has been recored in _summary_bytes_used.
5179   g1mm()->update_eden_size();
5180 }
5181 
5182 // Methods for the GC alloc regions
5183 
5184 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5185   if (dest.is_old()) {
5186     return true;
5187   } else {
5188     return survivor_regions_count() < g1_policy()->max_survivor_regions();
5189   }
5190 }
5191 
5192 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5193   assert(FreeList_lock->owned_by_self(), "pre-condition");
5194 
5195   if (!has_more_regions(dest)) {
5196     return NULL;
5197   }
5198 
5199   const bool is_survivor = dest.is_young();
5200 
5201   HeapRegion* new_alloc_region = new_region(word_size,
5202                                             !is_survivor,
5203                                             true /* do_expand */);
5204   if (new_alloc_region != NULL) {
5205     // We really only need to do this for old regions given that we
5206     // should never scan survivors. But it doesn't hurt to do it
5207     // for survivors too.
5208     new_alloc_region->record_timestamp();
5209     if (is_survivor) {
5210       new_alloc_region->set_survivor();
5211       _survivor.add(new_alloc_region);
5212       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5213     } else {
5214       new_alloc_region->set_old();
5215       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5216     }
5217     _hr_printer.alloc(new_alloc_region);
5218     bool during_im = collector_state()->during_initial_mark_pause();
5219     new_alloc_region->note_start_of_copying(during_im);
5220     return new_alloc_region;
5221   }
5222   return NULL;
5223 }
5224 
5225 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5226                                              size_t allocated_bytes,
5227                                              InCSetState dest) {
5228   bool during_im = collector_state()->during_initial_mark_pause();
5229   alloc_region->note_end_of_copying(during_im);
5230   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5231   if (dest.is_old()) {
5232     _old_set.add(alloc_region);
5233   }
5234   _hr_printer.retire(alloc_region);
5235 }
5236 
5237 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5238   bool expanded = false;
5239   uint index = _hrm.find_highest_free(&expanded);
5240 
5241   if (index != G1_NO_HRM_INDEX) {
5242     if (expanded) {
5243       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5244                                 HeapRegion::GrainWords * HeapWordSize);
5245     }
5246     _hrm.allocate_free_regions_starting_at(index, 1);
5247     return region_at(index);
5248   }
5249   return NULL;
5250 }
5251 
5252 // Optimized nmethod scanning
5253 
5254 class RegisterNMethodOopClosure: public OopClosure {
5255   G1CollectedHeap* _g1h;
5256   nmethod* _nm;
5257 
5258   template <class T> void do_oop_work(T* p) {
5259     T heap_oop = oopDesc::load_heap_oop(p);
5260     if (!oopDesc::is_null(heap_oop)) {
5261       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5262       HeapRegion* hr = _g1h->heap_region_containing(obj);
5263       assert(!hr->is_continues_humongous(),
5264              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5265              " starting at " HR_FORMAT,
5266              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5267 
5268       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5269       hr->add_strong_code_root_locked(_nm);
5270     }
5271   }
5272 
5273 public:
5274   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5275     _g1h(g1h), _nm(nm) {}
5276 
5277   void do_oop(oop* p)       { do_oop_work(p); }
5278   void do_oop(narrowOop* p) { do_oop_work(p); }
5279 };
5280 
5281 class UnregisterNMethodOopClosure: public OopClosure {
5282   G1CollectedHeap* _g1h;
5283   nmethod* _nm;
5284 
5285   template <class T> void do_oop_work(T* p) {
5286     T heap_oop = oopDesc::load_heap_oop(p);
5287     if (!oopDesc::is_null(heap_oop)) {
5288       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5289       HeapRegion* hr = _g1h->heap_region_containing(obj);
5290       assert(!hr->is_continues_humongous(),
5291              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5292              " starting at " HR_FORMAT,
5293              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5294 
5295       hr->remove_strong_code_root(_nm);
5296     }
5297   }
5298 
5299 public:
5300   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5301     _g1h(g1h), _nm(nm) {}
5302 
5303   void do_oop(oop* p)       { do_oop_work(p); }
5304   void do_oop(narrowOop* p) { do_oop_work(p); }
5305 };
5306 
5307 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5308   CollectedHeap::register_nmethod(nm);
5309 
5310   guarantee(nm != NULL, "sanity");
5311   RegisterNMethodOopClosure reg_cl(this, nm);
5312   nm->oops_do(&reg_cl);
5313 }
5314 
5315 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5316   CollectedHeap::unregister_nmethod(nm);
5317 
5318   guarantee(nm != NULL, "sanity");
5319   UnregisterNMethodOopClosure reg_cl(this, nm);
5320   nm->oops_do(&reg_cl, true);
5321 }
5322 
5323 void G1CollectedHeap::purge_code_root_memory() {
5324   double purge_start = os::elapsedTime();
5325   G1CodeRootSet::purge();
5326   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5327   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5328 }
5329 
5330 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5331   G1CollectedHeap* _g1h;
5332 
5333 public:
5334   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5335     _g1h(g1h) {}
5336 
5337   void do_code_blob(CodeBlob* cb) {
5338     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5339     if (nm == NULL) {
5340       return;
5341     }
5342 
5343     if (ScavengeRootsInCode) {
5344       _g1h->register_nmethod(nm);
5345     }
5346   }
5347 };
5348 
5349 void G1CollectedHeap::rebuild_strong_code_roots() {
5350   RebuildStrongCodeRootClosure blob_cl(this);
5351   CodeCache::blobs_do(&blob_cl);
5352 }
--- EOF ---