1 /*
   2  * Copyright (c) 2001, 2016, 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/g1GCPhaseTimes.hpp"
  42 #include "gc/g1/g1HeapSizingPolicy.hpp"
  43 #include "gc/g1/g1HeapTransition.hpp"
  44 #include "gc/g1/g1HeapVerifier.hpp"
  45 #include "gc/g1/g1MarkSweep.hpp"
  46 #include "gc/g1/g1OopClosures.inline.hpp"
  47 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  48 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  49 #include "gc/g1/g1RemSet.inline.hpp"
  50 #include "gc/g1/g1RootClosures.hpp"
  51 #include "gc/g1/g1RootProcessor.hpp"
  52 #include "gc/g1/g1StringDedup.hpp"
  53 #include "gc/g1/g1YCTypes.hpp"
  54 #include "gc/g1/heapRegion.inline.hpp"
  55 #include "gc/g1/heapRegionRemSet.hpp"
  56 #include "gc/g1/heapRegionSet.inline.hpp"
  57 #include "gc/g1/suspendibleThreadSet.hpp"
  58 #include "gc/g1/vm_operations_g1.hpp"
  59 #include "gc/shared/gcHeapSummary.hpp"
  60 #include "gc/shared/gcId.hpp"
  61 #include "gc/shared/gcLocker.inline.hpp"
  62 #include "gc/shared/gcTimer.hpp"
  63 #include "gc/shared/gcTrace.hpp"
  64 #include "gc/shared/gcTraceTime.inline.hpp"
  65 #include "gc/shared/generationSpec.hpp"
  66 #include "gc/shared/isGCActiveMark.hpp"
  67 #include "gc/shared/referenceProcessor.inline.hpp"
  68 #include "gc/shared/taskqueue.inline.hpp"
  69 #include "logging/log.hpp"
  70 #include "memory/allocation.hpp"
  71 #include "memory/iterator.hpp"
  72 #include "memory/resourceArea.hpp"
  73 #include "oops/oop.inline.hpp"
  74 #include "runtime/atomic.inline.hpp"
  75 #include "runtime/init.hpp"
  76 #include "runtime/orderAccess.inline.hpp"
  77 #include "runtime/vmThread.hpp"
  78 #include "utilities/globalDefinitions.hpp"
  79 #include "utilities/stack.inline.hpp"
  80 
  81 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  82 
  83 // INVARIANTS/NOTES
  84 //
  85 // All allocation activity covered by the G1CollectedHeap interface is
  86 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  87 // and allocate_new_tlab, which are the "entry" points to the
  88 // allocation code from the rest of the JVM.  (Note that this does not
  89 // apply to TLAB allocation, which is not part of this interface: it
  90 // is done by clients of this interface.)
  91 
  92 // Local to this file.
  93 
  94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  95   bool _concurrent;
  96 public:
  97   RefineCardTableEntryClosure() : _concurrent(true) { }
  98 
  99   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 100     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
 101     // This path is executed by the concurrent refine or mutator threads,
 102     // concurrently, and so we do not care if card_ptr contains references
 103     // that point into the collection set.
 104     assert(!oops_into_cset, "should be");
 105 
 106     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 107       // Caller will actually yield.
 108       return false;
 109     }
 110     // Otherwise, we finished successfully; return true.
 111     return true;
 112   }
 113 
 114   void set_concurrent(bool b) { _concurrent = b; }
 115 };
 116 
 117 
 118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 119  private:
 120   size_t _num_dirtied;
 121   G1CollectedHeap* _g1h;
 122   G1SATBCardTableLoggingModRefBS* _g1_bs;
 123 
 124   HeapRegion* region_for_card(jbyte* card_ptr) const {
 125     return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
 126   }
 127 
 128   bool will_become_free(HeapRegion* hr) const {
 129     // A region will be freed by free_collection_set if the region is in the
 130     // collection set and has not had an evacuation failure.
 131     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 132   }
 133 
 134  public:
 135   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 136     _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
 137 
 138   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 139     HeapRegion* hr = region_for_card(card_ptr);
 140 
 141     // Should only dirty cards in regions that won't be freed.
 142     if (!will_become_free(hr)) {
 143       *card_ptr = CardTableModRefBS::dirty_card_val();
 144       _num_dirtied++;
 145     }
 146 
 147     return true;
 148   }
 149 
 150   size_t num_dirtied()   const { return _num_dirtied; }
 151 };
 152 
 153 
 154 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 155   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 156 }
 157 
 158 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 159   // The from card cache is not the memory that is actually committed. So we cannot
 160   // take advantage of the zero_filled parameter.
 161   reset_from_card_cache(start_idx, num_regions);
 162 }
 163 
 164 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 165 {
 166   // Claim the right to put the region on the dirty cards region list
 167   // by installing a self pointer.
 168   HeapRegion* next = hr->get_next_dirty_cards_region();
 169   if (next == NULL) {
 170     HeapRegion* res = (HeapRegion*)
 171       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 172                           NULL);
 173     if (res == NULL) {
 174       HeapRegion* head;
 175       do {
 176         // Put the region to the dirty cards region list.
 177         head = _dirty_cards_region_list;
 178         next = (HeapRegion*)
 179           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 180         if (next == head) {
 181           assert(hr->get_next_dirty_cards_region() == hr,
 182                  "hr->get_next_dirty_cards_region() != hr");
 183           if (next == NULL) {
 184             // The last region in the list points to itself.
 185             hr->set_next_dirty_cards_region(hr);
 186           } else {
 187             hr->set_next_dirty_cards_region(next);
 188           }
 189         }
 190       } while (next != head);
 191     }
 192   }
 193 }
 194 
 195 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 196 {
 197   HeapRegion* head;
 198   HeapRegion* hr;
 199   do {
 200     head = _dirty_cards_region_list;
 201     if (head == NULL) {
 202       return NULL;
 203     }
 204     HeapRegion* new_head = head->get_next_dirty_cards_region();
 205     if (head == new_head) {
 206       // The last region.
 207       new_head = NULL;
 208     }
 209     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 210                                           head);
 211   } while (hr != head);
 212   assert(hr != NULL, "invariant");
 213   hr->set_next_dirty_cards_region(NULL);
 214   return hr;
 215 }
 216 
 217 // Returns true if the reference points to an object that
 218 // can move in an incremental collection.
 219 bool G1CollectedHeap::is_scavengable(const void* p) {
 220   HeapRegion* hr = heap_region_containing(p);
 221   return !hr->is_pinned();
 222 }
 223 
 224 // Private methods.
 225 
 226 HeapRegion*
 227 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 228   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 229   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 230     if (!_secondary_free_list.is_empty()) {
 231       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 232                                       "secondary_free_list has %u entries",
 233                                       _secondary_free_list.length());
 234       // It looks as if there are free regions available on the
 235       // secondary_free_list. Let's move them to the free_list and try
 236       // again to allocate from it.
 237       append_secondary_free_list();
 238 
 239       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 240              "empty we should have moved at least one entry to the free_list");
 241       HeapRegion* res = _hrm.allocate_free_region(is_old);
 242       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 243                                       "allocated " HR_FORMAT " from secondary_free_list",
 244                                       HR_FORMAT_PARAMS(res));
 245       return res;
 246     }
 247 
 248     // Wait here until we get notified either when (a) there are no
 249     // more free regions coming or (b) some regions have been moved on
 250     // the secondary_free_list.
 251     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 252   }
 253 
 254   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 255                                   "could not allocate from secondary_free_list");
 256   return NULL;
 257 }
 258 
 259 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 260   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 261          "the only time we use this to allocate a humongous region is "
 262          "when we are allocating a single humongous region");
 263 
 264   HeapRegion* res;
 265   if (G1StressConcRegionFreeing) {
 266     if (!_secondary_free_list.is_empty()) {
 267       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 268                                       "forced to look at the secondary_free_list");
 269       res = new_region_try_secondary_free_list(is_old);
 270       if (res != NULL) {
 271         return res;
 272       }
 273     }
 274   }
 275 
 276   res = _hrm.allocate_free_region(is_old);
 277 
 278   if (res == NULL) {
 279     log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 280                                     "res == NULL, trying the secondary_free_list");
 281     res = new_region_try_secondary_free_list(is_old);
 282   }
 283   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 284     // Currently, only attempts to allocate GC alloc regions set
 285     // do_expand to true. So, we should only reach here during a
 286     // safepoint. If this assumption changes we might have to
 287     // reconsider the use of _expand_heap_after_alloc_failure.
 288     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 289 
 290     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 291                               word_size * HeapWordSize);
 292 
 293     if (expand(word_size * HeapWordSize)) {
 294       // Given that expand() succeeded in expanding the heap, and we
 295       // always expand the heap by an amount aligned to the heap
 296       // region size, the free list should in theory not be empty.
 297       // In either case allocate_free_region() will check for NULL.
 298       res = _hrm.allocate_free_region(is_old);
 299     } else {
 300       _expand_heap_after_alloc_failure = false;
 301     }
 302   }
 303   return res;
 304 }
 305 
 306 HeapWord*
 307 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 308                                                            uint num_regions,
 309                                                            size_t word_size,
 310                                                            AllocationContext_t context) {
 311   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 312   assert(is_humongous(word_size), "word_size should be humongous");
 313   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 314 
 315   // Index of last region in the series.
 316   uint last = first + num_regions - 1;
 317 
 318   // We need to initialize the region(s) we just discovered. This is
 319   // a bit tricky given that it can happen concurrently with
 320   // refinement threads refining cards on these regions and
 321   // potentially wanting to refine the BOT as they are scanning
 322   // those cards (this can happen shortly after a cleanup; see CR
 323   // 6991377). So we have to set up the region(s) carefully and in
 324   // a specific order.
 325 
 326   // The word size sum of all the regions we will allocate.
 327   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 328   assert(word_size <= word_size_sum, "sanity");
 329 
 330   // This will be the "starts humongous" region.
 331   HeapRegion* first_hr = region_at(first);
 332   // The header of the new object will be placed at the bottom of
 333   // the first region.
 334   HeapWord* new_obj = first_hr->bottom();
 335   // This will be the new top of the new object.
 336   HeapWord* obj_top = new_obj + word_size;
 337 
 338   // First, we need to zero the header of the space that we will be
 339   // allocating. When we update top further down, some refinement
 340   // threads might try to scan the region. By zeroing the header we
 341   // ensure that any thread that will try to scan the region will
 342   // come across the zero klass word and bail out.
 343   //
 344   // NOTE: It would not have been correct to have used
 345   // CollectedHeap::fill_with_object() and make the space look like
 346   // an int array. The thread that is doing the allocation will
 347   // later update the object header to a potentially different array
 348   // type and, for a very short period of time, the klass and length
 349   // fields will be inconsistent. This could cause a refinement
 350   // thread to calculate the object size incorrectly.
 351   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 352 
 353   // How many words we use for filler objects.
 354   size_t word_fill_size = word_size_sum - word_size;
 355 
 356   // How many words memory we "waste" which cannot hold a filler object.
 357   size_t words_not_fillable = 0;
 358 
 359   if (word_fill_size >= min_fill_size()) {
 360     fill_with_objects(obj_top, word_fill_size);
 361   } else if (word_fill_size > 0) {
 362     // We have space to fill, but we cannot fit an object there.
 363     words_not_fillable = word_fill_size;
 364     word_fill_size = 0;
 365   }
 366 
 367   // We will set up the first region as "starts humongous". This
 368   // will also update the BOT covering all the regions to reflect
 369   // that there is a single object that starts at the bottom of the
 370   // first region.
 371   first_hr->set_starts_humongous(obj_top, word_fill_size);
 372   first_hr->set_allocation_context(context);
 373   // Then, if there are any, we will set up the "continues
 374   // humongous" regions.
 375   HeapRegion* hr = NULL;
 376   for (uint i = first + 1; i <= last; ++i) {
 377     hr = region_at(i);
 378     hr->set_continues_humongous(first_hr);
 379     hr->set_allocation_context(context);
 380   }
 381 
 382   // Up to this point no concurrent thread would have been able to
 383   // do any scanning on any region in this series. All the top
 384   // fields still point to bottom, so the intersection between
 385   // [bottom,top] and [card_start,card_end] will be empty. Before we
 386   // update the top fields, we'll do a storestore to make sure that
 387   // no thread sees the update to top before the zeroing of the
 388   // object header and the BOT initialization.
 389   OrderAccess::storestore();
 390 
 391   // Now, we will update the top fields of the "continues humongous"
 392   // regions except the last one.
 393   for (uint i = first; i < last; ++i) {
 394     hr = region_at(i);
 395     hr->set_top(hr->end());
 396   }
 397 
 398   hr = region_at(last);
 399   // If we cannot fit a filler object, we must set top to the end
 400   // of the humongous object, otherwise we cannot iterate the heap
 401   // and the BOT will not be complete.
 402   hr->set_top(hr->end() - words_not_fillable);
 403 
 404   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 405          "obj_top should be in last region");
 406 
 407   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 408 
 409   assert(words_not_fillable == 0 ||
 410          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 411          "Miscalculation in humongous allocation");
 412 
 413   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 414 
 415   for (uint i = first; i <= last; ++i) {
 416     hr = region_at(i);
 417     _humongous_set.add(hr);
 418     _hr_printer.alloc(hr);
 419   }
 420 
 421   return new_obj;
 422 }
 423 
 424 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 425   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 426   return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 427 }
 428 
 429 // If could fit into free regions w/o expansion, try.
 430 // Otherwise, if can expand, do so.
 431 // Otherwise, if using ex regions might help, try with ex given back.
 432 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 433   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 434 
 435   _verifier->verify_region_sets_optional();
 436 
 437   uint first = G1_NO_HRM_INDEX;
 438   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 439 
 440   if (obj_regions == 1) {
 441     // Only one region to allocate, try to use a fast path by directly allocating
 442     // from the free lists. Do not try to expand here, we will potentially do that
 443     // later.
 444     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 445     if (hr != NULL) {
 446       first = hr->hrm_index();
 447     }
 448   } else {
 449     // We can't allocate humongous regions spanning more than one region while
 450     // cleanupComplete() is running, since some of the regions we find to be
 451     // empty might not yet be added to the free list. It is not straightforward
 452     // to know in which list they are on so that we can remove them. We only
 453     // need to do this if we need to allocate more than one region to satisfy the
 454     // current humongous allocation request. If we are only allocating one region
 455     // we use the one-region region allocation code (see above), that already
 456     // potentially waits for regions from the secondary free list.
 457     wait_while_free_regions_coming();
 458     append_secondary_free_list_if_not_empty_with_lock();
 459 
 460     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 461     // are lucky enough to find some.
 462     first = _hrm.find_contiguous_only_empty(obj_regions);
 463     if (first != G1_NO_HRM_INDEX) {
 464       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 465     }
 466   }
 467 
 468   if (first == G1_NO_HRM_INDEX) {
 469     // Policy: We could not find enough regions for the humongous object in the
 470     // free list. Look through the heap to find a mix of free and uncommitted regions.
 471     // If so, try expansion.
 472     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 473     if (first != G1_NO_HRM_INDEX) {
 474       // We found something. Make sure these regions are committed, i.e. expand
 475       // the heap. Alternatively we could do a defragmentation GC.
 476       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 477                                     word_size * HeapWordSize);
 478 
 479 
 480       _hrm.expand_at(first, obj_regions);
 481       g1_policy()->record_new_heap_size(num_regions());
 482 
 483 #ifdef ASSERT
 484       for (uint i = first; i < first + obj_regions; ++i) {
 485         HeapRegion* hr = region_at(i);
 486         assert(hr->is_free(), "sanity");
 487         assert(hr->is_empty(), "sanity");
 488         assert(is_on_master_free_list(hr), "sanity");
 489       }
 490 #endif
 491       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 492     } else {
 493       // Policy: Potentially trigger a defragmentation GC.
 494     }
 495   }
 496 
 497   HeapWord* result = NULL;
 498   if (first != G1_NO_HRM_INDEX) {
 499     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 500                                                        word_size, context);
 501     assert(result != NULL, "it should always return a valid result");
 502 
 503     // A successful humongous object allocation changes the used space
 504     // information of the old generation so we need to recalculate the
 505     // sizes and update the jstat counters here.
 506     g1mm()->update_sizes();
 507   }
 508 
 509   _verifier->verify_region_sets_optional();
 510 
 511   return result;
 512 }
 513 
 514 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 515   assert_heap_not_locked_and_not_at_safepoint();
 516   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 517 
 518   uint dummy_gc_count_before;
 519   uint dummy_gclocker_retry_count = 0;
 520   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 521 }
 522 
 523 HeapWord*
 524 G1CollectedHeap::mem_allocate(size_t word_size,
 525                               bool*  gc_overhead_limit_was_exceeded) {
 526   assert_heap_not_locked_and_not_at_safepoint();
 527 
 528   // Loop until the allocation is satisfied, or unsatisfied after GC.
 529   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 530     uint gc_count_before;
 531 
 532     HeapWord* result = NULL;
 533     if (!is_humongous(word_size)) {
 534       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 535     } else {
 536       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 537     }
 538     if (result != NULL) {
 539       return result;
 540     }
 541 
 542     // Create the garbage collection operation...
 543     VM_G1CollectForAllocation op(gc_count_before, word_size);
 544     op.set_allocation_context(AllocationContext::current());
 545 
 546     // ...and get the VM thread to execute it.
 547     VMThread::execute(&op);
 548 
 549     if (op.prologue_succeeded() && op.pause_succeeded()) {
 550       // If the operation was successful we'll return the result even
 551       // if it is NULL. If the allocation attempt failed immediately
 552       // after a Full GC, it's unlikely we'll be able to allocate now.
 553       HeapWord* result = op.result();
 554       if (result != NULL && !is_humongous(word_size)) {
 555         // Allocations that take place on VM operations do not do any
 556         // card dirtying and we have to do it here. We only have to do
 557         // this for non-humongous allocations, though.
 558         dirty_young_block(result, word_size);
 559       }
 560       return result;
 561     } else {
 562       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 563         return NULL;
 564       }
 565       assert(op.result() == NULL,
 566              "the result should be NULL if the VM op did not succeed");
 567     }
 568 
 569     // Give a warning if we seem to be looping forever.
 570     if ((QueuedAllocationWarningCount > 0) &&
 571         (try_count % QueuedAllocationWarningCount == 0)) {
 572       log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
 573     }
 574   }
 575 
 576   ShouldNotReachHere();
 577   return NULL;
 578 }
 579 
 580 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 581                                                    AllocationContext_t context,
 582                                                    uint* gc_count_before_ret,
 583                                                    uint* gclocker_retry_count_ret) {
 584   // Make sure you read the note in attempt_allocation_humongous().
 585 
 586   assert_heap_not_locked_and_not_at_safepoint();
 587   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 588          "be called for humongous allocation requests");
 589 
 590   // We should only get here after the first-level allocation attempt
 591   // (attempt_allocation()) failed to allocate.
 592 
 593   // We will loop until a) we manage to successfully perform the
 594   // allocation or b) we successfully schedule a collection which
 595   // fails to perform the allocation. b) is the only case when we'll
 596   // return NULL.
 597   HeapWord* result = NULL;
 598   for (int try_count = 1; /* we'll return */; try_count += 1) {
 599     bool should_try_gc;
 600     uint gc_count_before;
 601 
 602     {
 603       MutexLockerEx x(Heap_lock);
 604       result = _allocator->attempt_allocation_locked(word_size, context);
 605       if (result != NULL) {
 606         return result;
 607       }
 608 
 609       if (GCLocker::is_active_and_needs_gc()) {
 610         if (g1_policy()->can_expand_young_list()) {
 611           // No need for an ergo verbose message here,
 612           // can_expand_young_list() does this when it returns true.
 613           result = _allocator->attempt_allocation_force(word_size, context);
 614           if (result != NULL) {
 615             return result;
 616           }
 617         }
 618         should_try_gc = false;
 619       } else {
 620         // The GCLocker may not be active but the GCLocker initiated
 621         // GC may not yet have been performed (GCLocker::needs_gc()
 622         // returns true). In this case we do not try this GC and
 623         // wait until the GCLocker initiated GC is performed, and
 624         // then retry the allocation.
 625         if (GCLocker::needs_gc()) {
 626           should_try_gc = false;
 627         } else {
 628           // Read the GC count while still holding the Heap_lock.
 629           gc_count_before = total_collections();
 630           should_try_gc = true;
 631         }
 632       }
 633     }
 634 
 635     if (should_try_gc) {
 636       bool succeeded;
 637       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 638                                    GCCause::_g1_inc_collection_pause);
 639       if (result != NULL) {
 640         assert(succeeded, "only way to get back a non-NULL result");
 641         return result;
 642       }
 643 
 644       if (succeeded) {
 645         // If we get here we successfully scheduled a collection which
 646         // failed to allocate. No point in trying to allocate
 647         // further. We'll just return NULL.
 648         MutexLockerEx x(Heap_lock);
 649         *gc_count_before_ret = total_collections();
 650         return NULL;
 651       }
 652     } else {
 653       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 654         MutexLockerEx x(Heap_lock);
 655         *gc_count_before_ret = total_collections();
 656         return NULL;
 657       }
 658       // The GCLocker is either active or the GCLocker initiated
 659       // GC has not yet been performed. Stall until it is and
 660       // then retry the allocation.
 661       GCLocker::stall_until_clear();
 662       (*gclocker_retry_count_ret) += 1;
 663     }
 664 
 665     // We can reach here if we were unsuccessful in scheduling a
 666     // collection (because another thread beat us to it) or if we were
 667     // stalled due to the GC locker. In either can we should retry the
 668     // allocation attempt in case another thread successfully
 669     // performed a collection and reclaimed enough space. We do the
 670     // first attempt (without holding the Heap_lock) here and the
 671     // follow-on attempt will be at the start of the next loop
 672     // iteration (after taking the Heap_lock).
 673     result = _allocator->attempt_allocation(word_size, context);
 674     if (result != NULL) {
 675       return result;
 676     }
 677 
 678     // Give a warning if we seem to be looping forever.
 679     if ((QueuedAllocationWarningCount > 0) &&
 680         (try_count % QueuedAllocationWarningCount == 0)) {
 681       log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
 682                       "retries %d times", try_count);
 683     }
 684   }
 685 
 686   ShouldNotReachHere();
 687   return NULL;
 688 }
 689 
 690 void G1CollectedHeap::begin_archive_alloc_range() {
 691   assert_at_safepoint(true /* should_be_vm_thread */);
 692   if (_archive_allocator == NULL) {
 693     _archive_allocator = G1ArchiveAllocator::create_allocator(this);
 694   }
 695 }
 696 
 697 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 698   // Allocations in archive regions cannot be of a size that would be considered
 699   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 700   // may be different at archive-restore time.
 701   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 702 }
 703 
 704 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 705   assert_at_safepoint(true /* should_be_vm_thread */);
 706   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 707   if (is_archive_alloc_too_large(word_size)) {
 708     return NULL;
 709   }
 710   return _archive_allocator->archive_mem_allocate(word_size);
 711 }
 712 
 713 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 714                                               size_t end_alignment_in_bytes) {
 715   assert_at_safepoint(true /* should_be_vm_thread */);
 716   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 717 
 718   // Call complete_archive to do the real work, filling in the MemRegion
 719   // array with the archive regions.
 720   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 721   delete _archive_allocator;
 722   _archive_allocator = NULL;
 723 }
 724 
 725 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 726   assert(ranges != NULL, "MemRegion array NULL");
 727   assert(count != 0, "No MemRegions provided");
 728   MemRegion reserved = _hrm.reserved();
 729   for (size_t i = 0; i < count; i++) {
 730     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 731       return false;
 732     }
 733   }
 734   return true;
 735 }
 736 
 737 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
 738   assert(!is_init_completed(), "Expect to be called at JVM init time");
 739   assert(ranges != NULL, "MemRegion array NULL");
 740   assert(count != 0, "No MemRegions provided");
 741   MutexLockerEx x(Heap_lock);
 742 
 743   MemRegion reserved = _hrm.reserved();
 744   HeapWord* prev_last_addr = NULL;
 745   HeapRegion* prev_last_region = NULL;
 746 
 747   // Temporarily disable pretouching of heap pages. This interface is used
 748   // when mmap'ing archived heap data in, so pre-touching is wasted.
 749   FlagSetting fs(AlwaysPreTouch, false);
 750 
 751   // Enable archive object checking in G1MarkSweep. We have to let it know
 752   // about each archive range, so that objects in those ranges aren't marked.
 753   G1MarkSweep::enable_archive_object_check();
 754 
 755   // For each specified MemRegion range, allocate the corresponding G1
 756   // regions and mark them as archive regions. We expect the ranges in
 757   // ascending starting address order, without overlap.
 758   for (size_t i = 0; i < count; i++) {
 759     MemRegion curr_range = ranges[i];
 760     HeapWord* start_address = curr_range.start();
 761     size_t word_size = curr_range.word_size();
 762     HeapWord* last_address = curr_range.last();
 763     size_t commits = 0;
 764 
 765     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 766               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 767               p2i(start_address), p2i(last_address));
 768     guarantee(start_address > prev_last_addr,
 769               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 770               p2i(start_address), p2i(prev_last_addr));
 771     prev_last_addr = last_address;
 772 
 773     // Check for ranges that start in the same G1 region in which the previous
 774     // range ended, and adjust the start address so we don't try to allocate
 775     // the same region again. If the current range is entirely within that
 776     // region, skip it, just adjusting the recorded top.
 777     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 778     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 779       start_address = start_region->end();
 780       if (start_address > last_address) {
 781         increase_used(word_size * HeapWordSize);
 782         start_region->set_top(last_address + 1);
 783         continue;
 784       }
 785       start_region->set_top(start_address);
 786       curr_range = MemRegion(start_address, last_address + 1);
 787       start_region = _hrm.addr_to_region(start_address);
 788     }
 789 
 790     // Perform the actual region allocation, exiting if it fails.
 791     // Then note how much new space we have allocated.
 792     if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
 793       return false;
 794     }
 795     increase_used(word_size * HeapWordSize);
 796     if (commits != 0) {
 797       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 798                                 HeapRegion::GrainWords * HeapWordSize * commits);
 799 
 800     }
 801 
 802     // Mark each G1 region touched by the range as archive, add it to the old set,
 803     // and set the allocation context and top.
 804     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 805     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 806     prev_last_region = last_region;
 807 
 808     while (curr_region != NULL) {
 809       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 810              "Region already in use (index %u)", curr_region->hrm_index());
 811       curr_region->set_allocation_context(AllocationContext::system());
 812       curr_region->set_archive();
 813       _hr_printer.alloc(curr_region);
 814       _old_set.add(curr_region);
 815       if (curr_region != last_region) {
 816         curr_region->set_top(curr_region->end());
 817         curr_region = _hrm.next_region_in_heap(curr_region);
 818       } else {
 819         curr_region->set_top(last_address + 1);
 820         curr_region = NULL;
 821       }
 822     }
 823 
 824     // Notify mark-sweep of the archive range.
 825     G1MarkSweep::set_range_archive(curr_range, true);
 826   }
 827   return true;
 828 }
 829 
 830 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 831   assert(!is_init_completed(), "Expect to be called at JVM init time");
 832   assert(ranges != NULL, "MemRegion array NULL");
 833   assert(count != 0, "No MemRegions provided");
 834   MemRegion reserved = _hrm.reserved();
 835   HeapWord *prev_last_addr = NULL;
 836   HeapRegion* prev_last_region = NULL;
 837 
 838   // For each MemRegion, create filler objects, if needed, in the G1 regions
 839   // that contain the address range. The address range actually within the
 840   // MemRegion will not be modified. That is assumed to have been initialized
 841   // elsewhere, probably via an mmap of archived heap data.
 842   MutexLockerEx x(Heap_lock);
 843   for (size_t i = 0; i < count; i++) {
 844     HeapWord* start_address = ranges[i].start();
 845     HeapWord* last_address = ranges[i].last();
 846 
 847     assert(reserved.contains(start_address) && reserved.contains(last_address),
 848            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 849            p2i(start_address), p2i(last_address));
 850     assert(start_address > prev_last_addr,
 851            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 852            p2i(start_address), p2i(prev_last_addr));
 853 
 854     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 855     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 856     HeapWord* bottom_address = start_region->bottom();
 857 
 858     // Check for a range beginning in the same region in which the
 859     // previous one ended.
 860     if (start_region == prev_last_region) {
 861       bottom_address = prev_last_addr + 1;
 862     }
 863 
 864     // Verify that the regions were all marked as archive regions by
 865     // alloc_archive_regions.
 866     HeapRegion* curr_region = start_region;
 867     while (curr_region != NULL) {
 868       guarantee(curr_region->is_archive(),
 869                 "Expected archive region at index %u", curr_region->hrm_index());
 870       if (curr_region != last_region) {
 871         curr_region = _hrm.next_region_in_heap(curr_region);
 872       } else {
 873         curr_region = NULL;
 874       }
 875     }
 876 
 877     prev_last_addr = last_address;
 878     prev_last_region = last_region;
 879 
 880     // Fill the memory below the allocated range with dummy object(s),
 881     // if the region bottom does not match the range start, or if the previous
 882     // range ended within the same G1 region, and there is a gap.
 883     if (start_address != bottom_address) {
 884       size_t fill_size = pointer_delta(start_address, bottom_address);
 885       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 886       increase_used(fill_size * HeapWordSize);
 887     }
 888   }
 889 }
 890 
 891 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
 892                                                      uint* gc_count_before_ret,
 893                                                      uint* gclocker_retry_count_ret) {
 894   assert_heap_not_locked_and_not_at_safepoint();
 895   assert(!is_humongous(word_size), "attempt_allocation() should not "
 896          "be called for humongous allocation requests");
 897 
 898   AllocationContext_t context = AllocationContext::current();
 899   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 900 
 901   if (result == NULL) {
 902     result = attempt_allocation_slow(word_size,
 903                                      context,
 904                                      gc_count_before_ret,
 905                                      gclocker_retry_count_ret);
 906   }
 907   assert_heap_not_locked();
 908   if (result != NULL) {
 909     dirty_young_block(result, word_size);
 910   }
 911   return result;
 912 }
 913 
 914 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 915   assert(!is_init_completed(), "Expect to be called at JVM init time");
 916   assert(ranges != NULL, "MemRegion array NULL");
 917   assert(count != 0, "No MemRegions provided");
 918   MemRegion reserved = _hrm.reserved();
 919   HeapWord* prev_last_addr = NULL;
 920   HeapRegion* prev_last_region = NULL;
 921   size_t size_used = 0;
 922   size_t uncommitted_regions = 0;
 923 
 924   // For each Memregion, free the G1 regions that constitute it, and
 925   // notify mark-sweep that the range is no longer to be considered 'archive.'
 926   MutexLockerEx x(Heap_lock);
 927   for (size_t i = 0; i < count; i++) {
 928     HeapWord* start_address = ranges[i].start();
 929     HeapWord* last_address = ranges[i].last();
 930 
 931     assert(reserved.contains(start_address) && reserved.contains(last_address),
 932            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 933            p2i(start_address), p2i(last_address));
 934     assert(start_address > prev_last_addr,
 935            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 936            p2i(start_address), p2i(prev_last_addr));
 937     size_used += ranges[i].byte_size();
 938     prev_last_addr = last_address;
 939 
 940     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 941     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 942 
 943     // Check for ranges that start in the same G1 region in which the previous
 944     // range ended, and adjust the start address so we don't try to free
 945     // the same region again. If the current range is entirely within that
 946     // region, skip it.
 947     if (start_region == prev_last_region) {
 948       start_address = start_region->end();
 949       if (start_address > last_address) {
 950         continue;
 951       }
 952       start_region = _hrm.addr_to_region(start_address);
 953     }
 954     prev_last_region = last_region;
 955 
 956     // After verifying that each region was marked as an archive region by
 957     // alloc_archive_regions, set it free and empty and uncommit it.
 958     HeapRegion* curr_region = start_region;
 959     while (curr_region != NULL) {
 960       guarantee(curr_region->is_archive(),
 961                 "Expected archive region at index %u", curr_region->hrm_index());
 962       uint curr_index = curr_region->hrm_index();
 963       _old_set.remove(curr_region);
 964       curr_region->set_free();
 965       curr_region->set_top(curr_region->bottom());
 966       if (curr_region != last_region) {
 967         curr_region = _hrm.next_region_in_heap(curr_region);
 968       } else {
 969         curr_region = NULL;
 970       }
 971       _hrm.shrink_at(curr_index, 1);
 972       uncommitted_regions++;
 973     }
 974 
 975     // Notify mark-sweep that this is no longer an archive range.
 976     G1MarkSweep::set_range_archive(ranges[i], false);
 977   }
 978 
 979   if (uncommitted_regions != 0) {
 980     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 981                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 982   }
 983   decrease_used(size_used);
 984 }
 985 
 986 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 987                                                         uint* gc_count_before_ret,
 988                                                         uint* gclocker_retry_count_ret) {
 989   // The structure of this method has a lot of similarities to
 990   // attempt_allocation_slow(). The reason these two were not merged
 991   // into a single one is that such a method would require several "if
 992   // allocation is not humongous do this, otherwise do that"
 993   // conditional paths which would obscure its flow. In fact, an early
 994   // version of this code did use a unified method which was harder to
 995   // follow and, as a result, it had subtle bugs that were hard to
 996   // track down. So keeping these two methods separate allows each to
 997   // be more readable. It will be good to keep these two in sync as
 998   // much as possible.
 999 
1000   assert_heap_not_locked_and_not_at_safepoint();
1001   assert(is_humongous(word_size), "attempt_allocation_humongous() "
1002          "should only be called for humongous allocations");
1003 
1004   // Humongous objects can exhaust the heap quickly, so we should check if we
1005   // need to start a marking cycle at each humongous object allocation. We do
1006   // the check before we do the actual allocation. The reason for doing it
1007   // before the allocation is that we avoid having to keep track of the newly
1008   // allocated memory while we do a GC.
1009   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1010                                            word_size)) {
1011     collect(GCCause::_g1_humongous_allocation);
1012   }
1013 
1014   // We will loop until a) we manage to successfully perform the
1015   // allocation or b) we successfully schedule a collection which
1016   // fails to perform the allocation. b) is the only case when we'll
1017   // return NULL.
1018   HeapWord* result = NULL;
1019   for (int try_count = 1; /* we'll return */; try_count += 1) {
1020     bool should_try_gc;
1021     uint gc_count_before;
1022 
1023     {
1024       MutexLockerEx x(Heap_lock);
1025 
1026       // Given that humongous objects are not allocated in young
1027       // regions, we'll first try to do the allocation without doing a
1028       // collection hoping that there's enough space in the heap.
1029       result = humongous_obj_allocate(word_size, AllocationContext::current());
1030       if (result != NULL) {
1031         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1032         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1033         return result;
1034       }
1035 
1036       if (GCLocker::is_active_and_needs_gc()) {
1037         should_try_gc = false;
1038       } else {
1039          // The GCLocker may not be active but the GCLocker initiated
1040         // GC may not yet have been performed (GCLocker::needs_gc()
1041         // returns true). In this case we do not try this GC and
1042         // wait until the GCLocker initiated GC is performed, and
1043         // then retry the allocation.
1044         if (GCLocker::needs_gc()) {
1045           should_try_gc = false;
1046         } else {
1047           // Read the GC count while still holding the Heap_lock.
1048           gc_count_before = total_collections();
1049           should_try_gc = true;
1050         }
1051       }
1052     }
1053 
1054     if (should_try_gc) {
1055       // If we failed to allocate the humongous object, we should try to
1056       // do a collection pause (if we're allowed) in case it reclaims
1057       // enough space for the allocation to succeed after the pause.
1058 
1059       bool succeeded;
1060       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1061                                    GCCause::_g1_humongous_allocation);
1062       if (result != NULL) {
1063         assert(succeeded, "only way to get back a non-NULL result");
1064         return result;
1065       }
1066 
1067       if (succeeded) {
1068         // If we get here we successfully scheduled a collection which
1069         // failed to allocate. No point in trying to allocate
1070         // further. We'll just return NULL.
1071         MutexLockerEx x(Heap_lock);
1072         *gc_count_before_ret = total_collections();
1073         return NULL;
1074       }
1075     } else {
1076       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1077         MutexLockerEx x(Heap_lock);
1078         *gc_count_before_ret = total_collections();
1079         return NULL;
1080       }
1081       // The GCLocker is either active or the GCLocker initiated
1082       // GC has not yet been performed. Stall until it is and
1083       // then retry the allocation.
1084       GCLocker::stall_until_clear();
1085       (*gclocker_retry_count_ret) += 1;
1086     }
1087 
1088     // We can reach here if we were unsuccessful in scheduling a
1089     // collection (because another thread beat us to it) or if we were
1090     // stalled due to the GC locker. In either can we should retry the
1091     // allocation attempt in case another thread successfully
1092     // performed a collection and reclaimed enough space.  Give a
1093     // warning if we seem to be looping forever.
1094 
1095     if ((QueuedAllocationWarningCount > 0) &&
1096         (try_count % QueuedAllocationWarningCount == 0)) {
1097       log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1098                       "retries %d times", try_count);
1099     }
1100   }
1101 
1102   ShouldNotReachHere();
1103   return NULL;
1104 }
1105 
1106 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1107                                                            AllocationContext_t context,
1108                                                            bool expect_null_mutator_alloc_region) {
1109   assert_at_safepoint(true /* should_be_vm_thread */);
1110   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1111          "the current alloc region was unexpectedly found to be non-NULL");
1112 
1113   if (!is_humongous(word_size)) {
1114     return _allocator->attempt_allocation_locked(word_size, context);
1115   } else {
1116     HeapWord* result = humongous_obj_allocate(word_size, context);
1117     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1118       collector_state()->set_initiate_conc_mark_if_possible(true);
1119     }
1120     return result;
1121   }
1122 
1123   ShouldNotReachHere();
1124 }
1125 
1126 class PostMCRemSetClearClosure: public HeapRegionClosure {
1127   G1CollectedHeap* _g1h;
1128   ModRefBarrierSet* _mr_bs;
1129 public:
1130   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1131     _g1h(g1h), _mr_bs(mr_bs) {}
1132 
1133   bool doHeapRegion(HeapRegion* r) {
1134     HeapRegionRemSet* hrrs = r->rem_set();
1135 
1136     _g1h->reset_gc_time_stamps(r);
1137 
1138     if (r->is_continues_humongous()) {
1139       // We'll assert that the strong code root list and RSet is empty
1140       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1141       assert(hrrs->occupied() == 0, "RSet should be empty");
1142     } else {
1143       hrrs->clear();
1144     }
1145     // You might think here that we could clear just the cards
1146     // corresponding to the used region.  But no: if we leave a dirty card
1147     // in a region we might allocate into, then it would prevent that card
1148     // from being enqueued, and cause it to be missed.
1149     // Re: the performance cost: we shouldn't be doing full GC anyway!
1150     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1151 
1152     return false;
1153   }
1154 };
1155 
1156 void G1CollectedHeap::clear_rsets_post_compaction() {
1157   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1158   heap_region_iterate(&rs_clear);
1159 }
1160 
1161 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1162   G1CollectedHeap*   _g1h;
1163   UpdateRSOopClosure _cl;
1164 public:
1165   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1166     _cl(g1->g1_rem_set(), worker_i),
1167     _g1h(g1)
1168   { }
1169 
1170   bool doHeapRegion(HeapRegion* r) {
1171     if (!r->is_continues_humongous()) {
1172       _cl.set_from(r);
1173       r->oop_iterate(&_cl);
1174     }
1175     return false;
1176   }
1177 };
1178 
1179 class ParRebuildRSTask: public AbstractGangTask {
1180   G1CollectedHeap* _g1;
1181   HeapRegionClaimer _hrclaimer;
1182 
1183 public:
1184   ParRebuildRSTask(G1CollectedHeap* g1) :
1185       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1186 
1187   void work(uint worker_id) {
1188     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1189     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1190   }
1191 };
1192 
1193 class PostCompactionPrinterClosure: public HeapRegionClosure {
1194 private:
1195   G1HRPrinter* _hr_printer;
1196 public:
1197   bool doHeapRegion(HeapRegion* hr) {
1198     assert(!hr->is_young(), "not expecting to find young regions");
1199     _hr_printer->post_compaction(hr);
1200     return false;
1201   }
1202 
1203   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1204     : _hr_printer(hr_printer) { }
1205 };
1206 
1207 void G1CollectedHeap::print_hrm_post_compaction() {
1208   if (_hr_printer.is_active()) {
1209     PostCompactionPrinterClosure cl(hr_printer());
1210     heap_region_iterate(&cl);
1211   }
1212 
1213 }
1214 
1215 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1216                                          bool clear_all_soft_refs) {
1217   assert_at_safepoint(true /* should_be_vm_thread */);
1218 
1219   if (GCLocker::check_active_before_gc()) {
1220     return false;
1221   }
1222 
1223   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1224   gc_timer->register_gc_start();
1225 
1226   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1227   GCIdMark gc_id_mark;
1228   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1229 
1230   SvcGCMarker sgcm(SvcGCMarker::FULL);
1231   ResourceMark rm;
1232 
1233   print_heap_before_gc();
1234   print_heap_regions();
1235   trace_heap_before_gc(gc_tracer);
1236 
1237   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1238 
1239   _verifier->verify_region_sets_optional();
1240 
1241   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1242                            collector_policy()->should_clear_all_soft_refs();
1243 
1244   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1245 
1246   {
1247     IsGCActiveMark x;
1248 
1249     // Timing
1250     assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1251     GCTraceCPUTime tcpu;
1252 
1253     {
1254       GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1255       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1256       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1257 
1258       G1HeapTransition heap_transition(this);
1259       g1_policy()->record_full_collection_start();
1260 
1261       // Note: When we have a more flexible GC logging framework that
1262       // allows us to add optional attributes to a GC log record we
1263       // could consider timing and reporting how long we wait in the
1264       // following two methods.
1265       wait_while_free_regions_coming();
1266       // If we start the compaction before the CM threads finish
1267       // scanning the root regions we might trip them over as we'll
1268       // be moving objects / updating references. So let's wait until
1269       // they are done. By telling them to abort, they should complete
1270       // early.
1271       _cm->root_regions()->abort();
1272       _cm->root_regions()->wait_until_scan_finished();
1273       append_secondary_free_list_if_not_empty_with_lock();
1274 
1275       gc_prologue(true);
1276       increment_total_collections(true /* full gc */);
1277       increment_old_marking_cycles_started();
1278 
1279       assert(used() == recalculate_used(), "Should be equal");
1280 
1281       _verifier->verify_before_gc();
1282 
1283       _verifier->check_bitmaps("Full GC Start");
1284       pre_full_gc_dump(gc_timer);
1285 
1286 #if defined(COMPILER2) || INCLUDE_JVMCI
1287       DerivedPointerTable::clear();
1288 #endif
1289 
1290       // Disable discovery and empty the discovered lists
1291       // for the CM ref processor.
1292       ref_processor_cm()->disable_discovery();
1293       ref_processor_cm()->abandon_partial_discovery();
1294       ref_processor_cm()->verify_no_references_recorded();
1295 
1296       // Abandon current iterations of concurrent marking and concurrent
1297       // refinement, if any are in progress.
1298       concurrent_mark()->abort();
1299 
1300       // Make sure we'll choose a new allocation region afterwards.
1301       _allocator->release_mutator_alloc_region();
1302       _allocator->abandon_gc_alloc_regions();
1303       g1_rem_set()->cleanupHRRS();
1304 
1305       // We may have added regions to the current incremental collection
1306       // set between the last GC or pause and now. We need to clear the
1307       // incremental collection set and then start rebuilding it afresh
1308       // after this full GC.
1309       abandon_collection_set(collection_set()->inc_head());
1310       collection_set()->clear_incremental();
1311       collection_set()->stop_incremental_building();
1312 
1313       tear_down_region_sets(false /* free_list_only */);
1314       collector_state()->set_gcs_are_young(true);
1315 
1316       // See the comments in g1CollectedHeap.hpp and
1317       // G1CollectedHeap::ref_processing_init() about
1318       // how reference processing currently works in G1.
1319 
1320       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1321       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1322 
1323       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1324       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1325 
1326       ref_processor_stw()->enable_discovery();
1327       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1328 
1329       // Do collection work
1330       {
1331         HandleMark hm;  // Discard invalid handles created during gc
1332         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1333       }
1334 
1335       assert(num_free_regions() == 0, "we should not have added any free regions");
1336       rebuild_region_sets(false /* free_list_only */);
1337 
1338       // Enqueue any discovered reference objects that have
1339       // not been removed from the discovered lists.
1340       ref_processor_stw()->enqueue_discovered_references();
1341 
1342 #if defined(COMPILER2) || INCLUDE_JVMCI
1343       DerivedPointerTable::update_pointers();
1344 #endif
1345 
1346       MemoryService::track_memory_usage();
1347 
1348       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1349       ref_processor_stw()->verify_no_references_recorded();
1350 
1351       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1352       ClassLoaderDataGraph::purge();
1353       MetaspaceAux::verify_metrics();
1354 
1355       // Note: since we've just done a full GC, concurrent
1356       // marking is no longer active. Therefore we need not
1357       // re-enable reference discovery for the CM ref processor.
1358       // That will be done at the start of the next marking cycle.
1359       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1360       ref_processor_cm()->verify_no_references_recorded();
1361 
1362       reset_gc_time_stamp();
1363       // Since everything potentially moved, we will clear all remembered
1364       // sets, and clear all cards.  Later we will rebuild remembered
1365       // sets. We will also reset the GC time stamps of the regions.
1366       clear_rsets_post_compaction();
1367       check_gc_time_stamps();
1368 
1369       resize_if_necessary_after_full_collection();
1370 
1371       // We should do this after we potentially resize the heap so
1372       // that all the COMMIT / UNCOMMIT events are generated before
1373       // the compaction events.
1374       print_hrm_post_compaction();
1375 
1376       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1377       if (hot_card_cache->use_cache()) {
1378         hot_card_cache->reset_card_counts();
1379         hot_card_cache->reset_hot_cache();
1380       }
1381 
1382       // Rebuild remembered sets of all regions.
1383       uint n_workers =
1384         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1385                                                 workers()->active_workers(),
1386                                                 Threads::number_of_non_daemon_threads());
1387       workers()->set_active_workers(n_workers);
1388 
1389       ParRebuildRSTask rebuild_rs_task(this);
1390       workers()->run_task(&rebuild_rs_task);
1391 
1392       // Rebuild the strong code root lists for each region
1393       rebuild_strong_code_roots();
1394 
1395       if (true) { // FIXME
1396         MetaspaceGC::compute_new_size();
1397       }
1398 
1399 #ifdef TRACESPINNING
1400       ParallelTaskTerminator::print_termination_counts();
1401 #endif
1402 
1403       // Discard all rset updates
1404       JavaThread::dirty_card_queue_set().abandon_logs();
1405       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1406 
1407       // At this point there should be no regions in the
1408       // entire heap tagged as young.
1409       assert(check_young_list_empty(true /* check_heap */),
1410              "young list should be empty at this point");
1411 
1412       // Update the number of full collections that have been completed.
1413       increment_old_marking_cycles_completed(false /* concurrent */);
1414 
1415       _hrm.verify_optional();
1416       _verifier->verify_region_sets_optional();
1417 
1418       _verifier->verify_after_gc();
1419 
1420       // Clear the previous marking bitmap, if needed for bitmap verification.
1421       // Note we cannot do this when we clear the next marking bitmap in
1422       // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1423       // objects marked during a full GC against the previous bitmap.
1424       // But we need to clear it before calling check_bitmaps below since
1425       // the full GC has compacted objects and updated TAMS but not updated
1426       // the prev bitmap.
1427       if (G1VerifyBitmaps) {
1428         GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1429         _cm->clear_prev_bitmap(workers());
1430       }
1431       _verifier->check_bitmaps("Full GC End");
1432 
1433       // Start a new incremental collection set for the next pause
1434       assert(collection_set()->head() == NULL, "must be");
1435       collection_set()->start_incremental_building();
1436 
1437       clear_cset_fast_test();
1438 
1439       _allocator->init_mutator_alloc_region();
1440 
1441       g1_policy()->record_full_collection_end();
1442 
1443       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1444       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1445       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1446       // before any GC notifications are raised.
1447       g1mm()->update_sizes();
1448 
1449       gc_epilogue(true);
1450 
1451       heap_transition.print();
1452 
1453       print_heap_after_gc();
1454       print_heap_regions();
1455       trace_heap_after_gc(gc_tracer);
1456 
1457       post_full_gc_dump(gc_timer);
1458     }
1459 
1460     gc_timer->register_gc_end();
1461     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1462   }
1463 
1464   return true;
1465 }
1466 
1467 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1468   // Currently, there is no facility in the do_full_collection(bool) API to notify
1469   // the caller that the collection did not succeed (e.g., because it was locked
1470   // out by the GC locker). So, right now, we'll ignore the return value.
1471   bool dummy = do_full_collection(true,                /* explicit_gc */
1472                                   clear_all_soft_refs);
1473 }
1474 
1475 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1476   // Include bytes that will be pre-allocated to support collections, as "used".
1477   const size_t used_after_gc = used();
1478   const size_t capacity_after_gc = capacity();
1479   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1480 
1481   // This is enforced in arguments.cpp.
1482   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1483          "otherwise the code below doesn't make sense");
1484 
1485   // We don't have floating point command-line arguments
1486   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1487   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1488   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1489   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1490 
1491   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1492   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1493 
1494   // We have to be careful here as these two calculations can overflow
1495   // 32-bit size_t's.
1496   double used_after_gc_d = (double) used_after_gc;
1497   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1498   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1499 
1500   // Let's make sure that they are both under the max heap size, which
1501   // by default will make them fit into a size_t.
1502   double desired_capacity_upper_bound = (double) max_heap_size;
1503   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1504                                     desired_capacity_upper_bound);
1505   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1506                                     desired_capacity_upper_bound);
1507 
1508   // We can now safely turn them into size_t's.
1509   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1510   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1511 
1512   // This assert only makes sense here, before we adjust them
1513   // with respect to the min and max heap size.
1514   assert(minimum_desired_capacity <= maximum_desired_capacity,
1515          "minimum_desired_capacity = " SIZE_FORMAT ", "
1516          "maximum_desired_capacity = " SIZE_FORMAT,
1517          minimum_desired_capacity, maximum_desired_capacity);
1518 
1519   // Should not be greater than the heap max size. No need to adjust
1520   // it with respect to the heap min size as it's a lower bound (i.e.,
1521   // we'll try to make the capacity larger than it, not smaller).
1522   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1523   // Should not be less than the heap min size. No need to adjust it
1524   // with respect to the heap max size as it's an upper bound (i.e.,
1525   // we'll try to make the capacity smaller than it, not greater).
1526   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1527 
1528   if (capacity_after_gc < minimum_desired_capacity) {
1529     // Don't expand unless it's significant
1530     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1531 
1532     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1533                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1534                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1535 
1536     expand(expand_bytes);
1537 
1538     // No expansion, now see if we want to shrink
1539   } else if (capacity_after_gc > maximum_desired_capacity) {
1540     // Capacity too large, compute shrinking size
1541     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1542 
1543     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1544                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1545                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1546 
1547     shrink(shrink_bytes);
1548   }
1549 }
1550 
1551 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1552                                                             AllocationContext_t context,
1553                                                             bool do_gc,
1554                                                             bool clear_all_soft_refs,
1555                                                             bool expect_null_mutator_alloc_region,
1556                                                             bool* gc_succeeded) {
1557   *gc_succeeded = true;
1558   // Let's attempt the allocation first.
1559   HeapWord* result =
1560     attempt_allocation_at_safepoint(word_size,
1561                                     context,
1562                                     expect_null_mutator_alloc_region);
1563   if (result != NULL) {
1564     assert(*gc_succeeded, "sanity");
1565     return result;
1566   }
1567 
1568   // In a G1 heap, we're supposed to keep allocation from failing by
1569   // incremental pauses.  Therefore, at least for now, we'll favor
1570   // expansion over collection.  (This might change in the future if we can
1571   // do something smarter than full collection to satisfy a failed alloc.)
1572   result = expand_and_allocate(word_size, context);
1573   if (result != NULL) {
1574     assert(*gc_succeeded, "sanity");
1575     return result;
1576   }
1577 
1578   if (do_gc) {
1579     // Expansion didn't work, we'll try to do a Full GC.
1580     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1581                                        clear_all_soft_refs);
1582   }
1583 
1584   return NULL;
1585 }
1586 
1587 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1588                                                      AllocationContext_t context,
1589                                                      bool* succeeded) {
1590   assert_at_safepoint(true /* should_be_vm_thread */);
1591 
1592   // Attempts to allocate followed by Full GC.
1593   HeapWord* result =
1594     satisfy_failed_allocation_helper(word_size,
1595                                      context,
1596                                      true,  /* do_gc */
1597                                      false, /* clear_all_soft_refs */
1598                                      false, /* expect_null_mutator_alloc_region */
1599                                      succeeded);
1600 
1601   if (result != NULL || !*succeeded) {
1602     return result;
1603   }
1604 
1605   // Attempts to allocate followed by Full GC that will collect all soft references.
1606   result = satisfy_failed_allocation_helper(word_size,
1607                                             context,
1608                                             true, /* do_gc */
1609                                             true, /* clear_all_soft_refs */
1610                                             true, /* expect_null_mutator_alloc_region */
1611                                             succeeded);
1612 
1613   if (result != NULL || !*succeeded) {
1614     return result;
1615   }
1616 
1617   // Attempts to allocate, no GC
1618   result = satisfy_failed_allocation_helper(word_size,
1619                                             context,
1620                                             false, /* do_gc */
1621                                             false, /* clear_all_soft_refs */
1622                                             true,  /* expect_null_mutator_alloc_region */
1623                                             succeeded);
1624 
1625   if (result != NULL) {
1626     assert(*succeeded, "sanity");
1627     return result;
1628   }
1629 
1630   assert(!collector_policy()->should_clear_all_soft_refs(),
1631          "Flag should have been handled and cleared prior to this point");
1632 
1633   // What else?  We might try synchronous finalization later.  If the total
1634   // space available is large enough for the allocation, then a more
1635   // complete compaction phase than we've tried so far might be
1636   // appropriate.
1637   assert(*succeeded, "sanity");
1638   return NULL;
1639 }
1640 
1641 // Attempting to expand the heap sufficiently
1642 // to support an allocation of the given "word_size".  If
1643 // successful, perform the allocation and return the address of the
1644 // allocated block, or else "NULL".
1645 
1646 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1647   assert_at_safepoint(true /* should_be_vm_thread */);
1648 
1649   _verifier->verify_region_sets_optional();
1650 
1651   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1652   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1653                             word_size * HeapWordSize);
1654 
1655 
1656   if (expand(expand_bytes)) {
1657     _hrm.verify_optional();
1658     _verifier->verify_region_sets_optional();
1659     return attempt_allocation_at_safepoint(word_size,
1660                                            context,
1661                                            false /* expect_null_mutator_alloc_region */);
1662   }
1663   return NULL;
1664 }
1665 
1666 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1667   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1668   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1669                                        HeapRegion::GrainBytes);
1670 
1671   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1672                             expand_bytes, aligned_expand_bytes);
1673 
1674   if (is_maximal_no_gc()) {
1675     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1676     return false;
1677   }
1678 
1679   double expand_heap_start_time_sec = os::elapsedTime();
1680   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1681   assert(regions_to_expand > 0, "Must expand by at least one region");
1682 
1683   uint expanded_by = _hrm.expand_by(regions_to_expand);
1684   if (expand_time_ms != NULL) {
1685     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1686   }
1687 
1688   if (expanded_by > 0) {
1689     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1690     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1691     g1_policy()->record_new_heap_size(num_regions());
1692   } else {
1693     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1694 
1695     // The expansion of the virtual storage space was unsuccessful.
1696     // Let's see if it was because we ran out of swap.
1697     if (G1ExitOnExpansionFailure &&
1698         _hrm.available() >= regions_to_expand) {
1699       // We had head room...
1700       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1701     }
1702   }
1703   return regions_to_expand > 0;
1704 }
1705 
1706 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1707   size_t aligned_shrink_bytes =
1708     ReservedSpace::page_align_size_down(shrink_bytes);
1709   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1710                                          HeapRegion::GrainBytes);
1711   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1712 
1713   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1714   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1715 
1716 
1717   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",
1718                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1719   if (num_regions_removed > 0) {
1720     g1_policy()->record_new_heap_size(num_regions());
1721   } else {
1722     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1723   }
1724 }
1725 
1726 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1727   _verifier->verify_region_sets_optional();
1728 
1729   // We should only reach here at the end of a Full GC which means we
1730   // should not not be holding to any GC alloc regions. The method
1731   // below will make sure of that and do any remaining clean up.
1732   _allocator->abandon_gc_alloc_regions();
1733 
1734   // Instead of tearing down / rebuilding the free lists here, we
1735   // could instead use the remove_all_pending() method on free_list to
1736   // remove only the ones that we need to remove.
1737   tear_down_region_sets(true /* free_list_only */);
1738   shrink_helper(shrink_bytes);
1739   rebuild_region_sets(true /* free_list_only */);
1740 
1741   _hrm.verify_optional();
1742   _verifier->verify_region_sets_optional();
1743 }
1744 
1745 // Public methods.
1746 
1747 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1748   CollectedHeap(),
1749   _g1_policy(policy_),
1750   _collection_set(this),
1751   _dirty_card_queue_set(false),
1752   _is_alive_closure_cm(this),
1753   _is_alive_closure_stw(this),
1754   _ref_processor_cm(NULL),
1755   _ref_processor_stw(NULL),
1756   _bot(NULL),
1757   _cg1r(NULL),
1758   _g1mm(NULL),
1759   _refine_cte_cl(NULL),
1760   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1761   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1762   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1763   _humongous_reclaim_candidates(),
1764   _has_humongous_reclaim_candidates(false),
1765   _archive_allocator(NULL),
1766   _free_regions_coming(false),
1767   _young_list(new YoungList(this)),
1768   _gc_time_stamp(0),
1769   _summary_bytes_used(0),
1770   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1771   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1772   _expand_heap_after_alloc_failure(true),
1773   _old_marking_cycles_started(0),
1774   _old_marking_cycles_completed(0),
1775   _in_cset_fast_test(),
1776   _dirty_cards_region_list(NULL),
1777   _worker_cset_start_region(NULL),
1778   _worker_cset_start_region_time_stamp(NULL),
1779   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1780   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1781 
1782   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1783                           /* are_GC_task_threads */true,
1784                           /* are_ConcurrentGC_threads */false);
1785   _workers->initialize_workers();
1786   _verifier = new G1HeapVerifier(this);
1787 
1788   _allocator = G1Allocator::create_allocator(this);
1789 
1790   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1791 
1792   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1793 
1794   // Override the default _filler_array_max_size so that no humongous filler
1795   // objects are created.
1796   _filler_array_max_size = _humongous_object_threshold_in_words;
1797 
1798   uint n_queues = ParallelGCThreads;
1799   _task_queues = new RefToScanQueueSet(n_queues);
1800 
1801   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1802   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1803   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1804 
1805   for (uint i = 0; i < n_queues; i++) {
1806     RefToScanQueue* q = new RefToScanQueue();
1807     q->initialize();
1808     _task_queues->register_queue(i, q);
1809     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1810   }
1811   clear_cset_start_regions();
1812 
1813   // Initialize the G1EvacuationFailureALot counters and flags.
1814   NOT_PRODUCT(reset_evacuation_should_fail();)
1815 
1816   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1817 }
1818 
1819 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1820                                                                  size_t size,
1821                                                                  size_t translation_factor) {
1822   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1823   // Allocate a new reserved space, preferring to use large pages.
1824   ReservedSpace rs(size, preferred_page_size);
1825   G1RegionToSpaceMapper* result  =
1826     G1RegionToSpaceMapper::create_mapper(rs,
1827                                          size,
1828                                          rs.alignment(),
1829                                          HeapRegion::GrainBytes,
1830                                          translation_factor,
1831                                          mtGC);
1832   if (TracePageSizes) {
1833     tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1834                   description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1835   }
1836   return result;
1837 }
1838 
1839 jint G1CollectedHeap::initialize() {
1840   CollectedHeap::pre_initialize();
1841   os::enable_vtime();
1842 
1843   // Necessary to satisfy locking discipline assertions.
1844 
1845   MutexLocker x(Heap_lock);
1846 
1847   // While there are no constraints in the GC code that HeapWordSize
1848   // be any particular value, there are multiple other areas in the
1849   // system which believe this to be true (e.g. oop->object_size in some
1850   // cases incorrectly returns the size in wordSize units rather than
1851   // HeapWordSize).
1852   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1853 
1854   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1855   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1856   size_t heap_alignment = collector_policy()->heap_alignment();
1857 
1858   // Ensure that the sizes are properly aligned.
1859   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1860   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1861   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1862 
1863   _refine_cte_cl = new RefineCardTableEntryClosure();
1864 
1865   jint ecode = JNI_OK;
1866   _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1867   if (_cg1r == NULL) {
1868     return ecode;
1869   }
1870 
1871   // Reserve the maximum.
1872 
1873   // When compressed oops are enabled, the preferred heap base
1874   // is calculated by subtracting the requested size from the
1875   // 32Gb boundary and using the result as the base address for
1876   // heap reservation. If the requested size is not aligned to
1877   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1878   // into the ReservedHeapSpace constructor) then the actual
1879   // base of the reserved heap may end up differing from the
1880   // address that was requested (i.e. the preferred heap base).
1881   // If this happens then we could end up using a non-optimal
1882   // compressed oops mode.
1883 
1884   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1885                                                  heap_alignment);
1886 
1887   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1888 
1889   // Create the barrier set for the entire reserved region.
1890   G1SATBCardTableLoggingModRefBS* bs
1891     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1892   bs->initialize();
1893   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1894   set_barrier_set(bs);
1895 
1896   // Also create a G1 rem set.
1897   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1898 
1899   // Carve out the G1 part of the heap.
1900   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1901   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1902   G1RegionToSpaceMapper* heap_storage =
1903     G1RegionToSpaceMapper::create_mapper(g1_rs,
1904                                          g1_rs.size(),
1905                                          page_size,
1906                                          HeapRegion::GrainBytes,
1907                                          1,
1908                                          mtJavaHeap);
1909   os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1910                        max_byte_size, page_size,
1911                        heap_rs.base(),
1912                        heap_rs.size());
1913   heap_storage->set_mapping_changed_listener(&_listener);
1914 
1915   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1916   G1RegionToSpaceMapper* bot_storage =
1917     create_aux_memory_mapper("Block offset table",
1918                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1919                              G1BlockOffsetTable::heap_map_factor());
1920 
1921   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1922   G1RegionToSpaceMapper* cardtable_storage =
1923     create_aux_memory_mapper("Card table",
1924                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1925                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1926 
1927   G1RegionToSpaceMapper* card_counts_storage =
1928     create_aux_memory_mapper("Card counts table",
1929                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1930                              G1CardCounts::heap_map_factor());
1931 
1932   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1933   G1RegionToSpaceMapper* prev_bitmap_storage =
1934     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1935   G1RegionToSpaceMapper* next_bitmap_storage =
1936     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1937 
1938   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1939   g1_barrier_set()->initialize(cardtable_storage);
1940    // Do later initialization work for concurrent refinement.
1941   _cg1r->init(card_counts_storage);
1942 
1943   // 6843694 - ensure that the maximum region index can fit
1944   // in the remembered set structures.
1945   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1946   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1947 
1948   g1_rem_set()->initialize(max_capacity(), max_regions());
1949 
1950   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1951   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1952   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1953             "too many cards per region");
1954 
1955   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1956 
1957   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1958 
1959   {
1960     HeapWord* start = _hrm.reserved().start();
1961     HeapWord* end = _hrm.reserved().end();
1962     size_t granularity = HeapRegion::GrainBytes;
1963 
1964     _in_cset_fast_test.initialize(start, end, granularity);
1965     _humongous_reclaim_candidates.initialize(start, end, granularity);
1966   }
1967 
1968   // Create the G1ConcurrentMark data structure and thread.
1969   // (Must do this late, so that "max_regions" is defined.)
1970   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1971   if (_cm == NULL || !_cm->completed_initialization()) {
1972     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1973     return JNI_ENOMEM;
1974   }
1975   _cmThread = _cm->cmThread();
1976 
1977   // Now expand into the initial heap size.
1978   if (!expand(init_byte_size)) {
1979     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1980     return JNI_ENOMEM;
1981   }
1982 
1983   // Perform any initialization actions delegated to the policy.
1984   g1_policy()->init();
1985 
1986   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1987                                                SATB_Q_FL_lock,
1988                                                G1SATBProcessCompletedThreshold,
1989                                                Shared_SATB_Q_lock);
1990 
1991   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1992                                                 DirtyCardQ_CBL_mon,
1993                                                 DirtyCardQ_FL_lock,
1994                                                 (int)concurrent_g1_refine()->yellow_zone(),
1995                                                 (int)concurrent_g1_refine()->red_zone(),
1996                                                 Shared_DirtyCardQ_lock,
1997                                                 NULL,  // fl_owner
1998                                                 true); // init_free_ids
1999 
2000   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2001                                     DirtyCardQ_CBL_mon,
2002                                     DirtyCardQ_FL_lock,
2003                                     -1, // never trigger processing
2004                                     -1, // no limit on length
2005                                     Shared_DirtyCardQ_lock,
2006                                     &JavaThread::dirty_card_queue_set());
2007 
2008   // Here we allocate the dummy HeapRegion that is required by the
2009   // G1AllocRegion class.
2010   HeapRegion* dummy_region = _hrm.get_dummy_region();
2011 
2012   // We'll re-use the same region whether the alloc region will
2013   // require BOT updates or not and, if it doesn't, then a non-young
2014   // region will complain that it cannot support allocations without
2015   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2016   dummy_region->set_eden();
2017   // Make sure it's full.
2018   dummy_region->set_top(dummy_region->end());
2019   G1AllocRegion::setup(this, dummy_region);
2020 
2021   _allocator->init_mutator_alloc_region();
2022 
2023   // Do create of the monitoring and management support so that
2024   // values in the heap have been properly initialized.
2025   _g1mm = new G1MonitoringSupport(this);
2026 
2027   G1StringDedup::initialize();
2028 
2029   _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2030   for (uint i = 0; i < ParallelGCThreads; i++) {
2031     new (&_preserved_objs[i]) OopAndMarkOopStack();
2032   }
2033 
2034   return JNI_OK;
2035 }
2036 
2037 void G1CollectedHeap::stop() {
2038   // Stop all concurrent threads. We do this to make sure these threads
2039   // do not continue to execute and access resources (e.g. logging)
2040   // that are destroyed during shutdown.
2041   _cg1r->stop();
2042   _cmThread->stop();
2043   if (G1StringDedup::is_enabled()) {
2044     G1StringDedup::stop();
2045   }
2046 }
2047 
2048 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2049   return HeapRegion::max_region_size();
2050 }
2051 
2052 void G1CollectedHeap::post_initialize() {
2053   CollectedHeap::post_initialize();
2054   ref_processing_init();
2055 }
2056 
2057 void G1CollectedHeap::ref_processing_init() {
2058   // Reference processing in G1 currently works as follows:
2059   //
2060   // * There are two reference processor instances. One is
2061   //   used to record and process discovered references
2062   //   during concurrent marking; the other is used to
2063   //   record and process references during STW pauses
2064   //   (both full and incremental).
2065   // * Both ref processors need to 'span' the entire heap as
2066   //   the regions in the collection set may be dotted around.
2067   //
2068   // * For the concurrent marking ref processor:
2069   //   * Reference discovery is enabled at initial marking.
2070   //   * Reference discovery is disabled and the discovered
2071   //     references processed etc during remarking.
2072   //   * Reference discovery is MT (see below).
2073   //   * Reference discovery requires a barrier (see below).
2074   //   * Reference processing may or may not be MT
2075   //     (depending on the value of ParallelRefProcEnabled
2076   //     and ParallelGCThreads).
2077   //   * A full GC disables reference discovery by the CM
2078   //     ref processor and abandons any entries on it's
2079   //     discovered lists.
2080   //
2081   // * For the STW processor:
2082   //   * Non MT discovery is enabled at the start of a full GC.
2083   //   * Processing and enqueueing during a full GC is non-MT.
2084   //   * During a full GC, references are processed after marking.
2085   //
2086   //   * Discovery (may or may not be MT) is enabled at the start
2087   //     of an incremental evacuation pause.
2088   //   * References are processed near the end of a STW evacuation pause.
2089   //   * For both types of GC:
2090   //     * Discovery is atomic - i.e. not concurrent.
2091   //     * Reference discovery will not need a barrier.
2092 
2093   MemRegion mr = reserved_region();
2094 
2095   // Concurrent Mark ref processor
2096   _ref_processor_cm =
2097     new ReferenceProcessor(mr,    // span
2098                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2099                                 // mt processing
2100                            ParallelGCThreads,
2101                                 // degree of mt processing
2102                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2103                                 // mt discovery
2104                            MAX2(ParallelGCThreads, ConcGCThreads),
2105                                 // degree of mt discovery
2106                            false,
2107                                 // Reference discovery is not atomic
2108                            &_is_alive_closure_cm);
2109                                 // is alive closure
2110                                 // (for efficiency/performance)
2111 
2112   // STW ref processor
2113   _ref_processor_stw =
2114     new ReferenceProcessor(mr,    // span
2115                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2116                                 // mt processing
2117                            ParallelGCThreads,
2118                                 // degree of mt processing
2119                            (ParallelGCThreads > 1),
2120                                 // mt discovery
2121                            ParallelGCThreads,
2122                                 // degree of mt discovery
2123                            true,
2124                                 // Reference discovery is atomic
2125                            &_is_alive_closure_stw);
2126                                 // is alive closure
2127                                 // (for efficiency/performance)
2128 }
2129 
2130 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2131   return g1_policy();
2132 }
2133 
2134 size_t G1CollectedHeap::capacity() const {
2135   return _hrm.length() * HeapRegion::GrainBytes;
2136 }
2137 
2138 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2139   hr->reset_gc_time_stamp();
2140 }
2141 
2142 #ifndef PRODUCT
2143 
2144 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2145 private:
2146   unsigned _gc_time_stamp;
2147   bool _failures;
2148 
2149 public:
2150   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2151     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2152 
2153   virtual bool doHeapRegion(HeapRegion* hr) {
2154     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2155     if (_gc_time_stamp != region_gc_time_stamp) {
2156       log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2157                             region_gc_time_stamp, _gc_time_stamp);
2158       _failures = true;
2159     }
2160     return false;
2161   }
2162 
2163   bool failures() { return _failures; }
2164 };
2165 
2166 void G1CollectedHeap::check_gc_time_stamps() {
2167   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2168   heap_region_iterate(&cl);
2169   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2170 }
2171 #endif // PRODUCT
2172 
2173 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2174   _cg1r->hot_card_cache()->drain(cl, worker_i);
2175 }
2176 
2177 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2178   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2179   size_t n_completed_buffers = 0;
2180   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2181     n_completed_buffers++;
2182   }
2183   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2184   dcqs.clear_n_completed_buffers();
2185   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2186 }
2187 
2188 // Computes the sum of the storage used by the various regions.
2189 size_t G1CollectedHeap::used() const {
2190   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2191   if (_archive_allocator != NULL) {
2192     result += _archive_allocator->used();
2193   }
2194   return result;
2195 }
2196 
2197 size_t G1CollectedHeap::used_unlocked() const {
2198   return _summary_bytes_used;
2199 }
2200 
2201 class SumUsedClosure: public HeapRegionClosure {
2202   size_t _used;
2203 public:
2204   SumUsedClosure() : _used(0) {}
2205   bool doHeapRegion(HeapRegion* r) {
2206     _used += r->used();
2207     return false;
2208   }
2209   size_t result() { return _used; }
2210 };
2211 
2212 size_t G1CollectedHeap::recalculate_used() const {
2213   double recalculate_used_start = os::elapsedTime();
2214 
2215   SumUsedClosure blk;
2216   heap_region_iterate(&blk);
2217 
2218   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2219   return blk.result();
2220 }
2221 
2222 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2223   switch (cause) {
2224     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2225     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2226     case GCCause::_update_allocation_context_stats_inc: return true;
2227     case GCCause::_wb_conc_mark:                        return true;
2228     default :                                           return false;
2229   }
2230 }
2231 
2232 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2233   switch (cause) {
2234     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2235     case GCCause::_g1_humongous_allocation: return true;
2236     default:                                return is_user_requested_concurrent_full_gc(cause);
2237   }
2238 }
2239 
2240 #ifndef PRODUCT
2241 void G1CollectedHeap::allocate_dummy_regions() {
2242   // Let's fill up most of the region
2243   size_t word_size = HeapRegion::GrainWords - 1024;
2244   // And as a result the region we'll allocate will be humongous.
2245   guarantee(is_humongous(word_size), "sanity");
2246 
2247   // _filler_array_max_size is set to humongous object threshold
2248   // but temporarily change it to use CollectedHeap::fill_with_object().
2249   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2250 
2251   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2252     // Let's use the existing mechanism for the allocation
2253     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2254                                                  AllocationContext::system());
2255     if (dummy_obj != NULL) {
2256       MemRegion mr(dummy_obj, word_size);
2257       CollectedHeap::fill_with_object(mr);
2258     } else {
2259       // If we can't allocate once, we probably cannot allocate
2260       // again. Let's get out of the loop.
2261       break;
2262     }
2263   }
2264 }
2265 #endif // !PRODUCT
2266 
2267 void G1CollectedHeap::increment_old_marking_cycles_started() {
2268   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2269          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2270          "Wrong marking cycle count (started: %d, completed: %d)",
2271          _old_marking_cycles_started, _old_marking_cycles_completed);
2272 
2273   _old_marking_cycles_started++;
2274 }
2275 
2276 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2277   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2278 
2279   // We assume that if concurrent == true, then the caller is a
2280   // concurrent thread that was joined the Suspendible Thread
2281   // Set. If there's ever a cheap way to check this, we should add an
2282   // assert here.
2283 
2284   // Given that this method is called at the end of a Full GC or of a
2285   // concurrent cycle, and those can be nested (i.e., a Full GC can
2286   // interrupt a concurrent cycle), the number of full collections
2287   // completed should be either one (in the case where there was no
2288   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2289   // behind the number of full collections started.
2290 
2291   // This is the case for the inner caller, i.e. a Full GC.
2292   assert(concurrent ||
2293          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2294          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2295          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2296          "is inconsistent with _old_marking_cycles_completed = %u",
2297          _old_marking_cycles_started, _old_marking_cycles_completed);
2298 
2299   // This is the case for the outer caller, i.e. the concurrent cycle.
2300   assert(!concurrent ||
2301          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2302          "for outer caller (concurrent cycle): "
2303          "_old_marking_cycles_started = %u "
2304          "is inconsistent with _old_marking_cycles_completed = %u",
2305          _old_marking_cycles_started, _old_marking_cycles_completed);
2306 
2307   _old_marking_cycles_completed += 1;
2308 
2309   // We need to clear the "in_progress" flag in the CM thread before
2310   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2311   // is set) so that if a waiter requests another System.gc() it doesn't
2312   // incorrectly see that a marking cycle is still in progress.
2313   if (concurrent) {
2314     _cmThread->set_idle();
2315   }
2316 
2317   // This notify_all() will ensure that a thread that called
2318   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2319   // and it's waiting for a full GC to finish will be woken up. It is
2320   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2321   FullGCCount_lock->notify_all();
2322 }
2323 
2324 void G1CollectedHeap::collect(GCCause::Cause cause) {
2325   assert_heap_not_locked();
2326 
2327   uint gc_count_before;
2328   uint old_marking_count_before;
2329   uint full_gc_count_before;
2330   bool retry_gc;
2331 
2332   do {
2333     retry_gc = false;
2334 
2335     {
2336       MutexLocker ml(Heap_lock);
2337 
2338       // Read the GC count while holding the Heap_lock
2339       gc_count_before = total_collections();
2340       full_gc_count_before = total_full_collections();
2341       old_marking_count_before = _old_marking_cycles_started;
2342     }
2343 
2344     if (should_do_concurrent_full_gc(cause)) {
2345       // Schedule an initial-mark evacuation pause that will start a
2346       // concurrent cycle. We're setting word_size to 0 which means that
2347       // we are not requesting a post-GC allocation.
2348       VM_G1IncCollectionPause op(gc_count_before,
2349                                  0,     /* word_size */
2350                                  true,  /* should_initiate_conc_mark */
2351                                  g1_policy()->max_pause_time_ms(),
2352                                  cause);
2353       op.set_allocation_context(AllocationContext::current());
2354 
2355       VMThread::execute(&op);
2356       if (!op.pause_succeeded()) {
2357         if (old_marking_count_before == _old_marking_cycles_started) {
2358           retry_gc = op.should_retry_gc();
2359         } else {
2360           // A Full GC happened while we were trying to schedule the
2361           // initial-mark GC. No point in starting a new cycle given
2362           // that the whole heap was collected anyway.
2363         }
2364 
2365         if (retry_gc) {
2366           if (GCLocker::is_active_and_needs_gc()) {
2367             GCLocker::stall_until_clear();
2368           }
2369         }
2370       }
2371     } else {
2372       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2373           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2374 
2375         // Schedule a standard evacuation pause. We're setting word_size
2376         // to 0 which means that we are not requesting a post-GC allocation.
2377         VM_G1IncCollectionPause op(gc_count_before,
2378                                    0,     /* word_size */
2379                                    false, /* should_initiate_conc_mark */
2380                                    g1_policy()->max_pause_time_ms(),
2381                                    cause);
2382         VMThread::execute(&op);
2383       } else {
2384         // Schedule a Full GC.
2385         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2386         VMThread::execute(&op);
2387       }
2388     }
2389   } while (retry_gc);
2390 }
2391 
2392 bool G1CollectedHeap::is_in(const void* p) const {
2393   if (_hrm.reserved().contains(p)) {
2394     // Given that we know that p is in the reserved space,
2395     // heap_region_containing() should successfully
2396     // return the containing region.
2397     HeapRegion* hr = heap_region_containing(p);
2398     return hr->is_in(p);
2399   } else {
2400     return false;
2401   }
2402 }
2403 
2404 #ifdef ASSERT
2405 bool G1CollectedHeap::is_in_exact(const void* p) const {
2406   bool contains = reserved_region().contains(p);
2407   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2408   if (contains && available) {
2409     return true;
2410   } else {
2411     return false;
2412   }
2413 }
2414 #endif
2415 
2416 bool G1CollectedHeap::obj_in_cs(oop obj) {
2417   HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2418   return r != NULL && r->in_collection_set();
2419 }
2420 
2421 // Iteration functions.
2422 
2423 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2424 
2425 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2426   ExtendedOopClosure* _cl;
2427 public:
2428   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2429   bool doHeapRegion(HeapRegion* r) {
2430     if (!r->is_continues_humongous()) {
2431       r->oop_iterate(_cl);
2432     }
2433     return false;
2434   }
2435 };
2436 
2437 // Iterates an ObjectClosure over all objects within a HeapRegion.
2438 
2439 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2440   ObjectClosure* _cl;
2441 public:
2442   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2443   bool doHeapRegion(HeapRegion* r) {
2444     if (!r->is_continues_humongous()) {
2445       r->object_iterate(_cl);
2446     }
2447     return false;
2448   }
2449 };
2450 
2451 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2452   IterateObjectClosureRegionClosure blk(cl);
2453   heap_region_iterate(&blk);
2454 }
2455 
2456 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2457   _hrm.iterate(cl);
2458 }
2459 
2460 void
2461 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2462                                          uint worker_id,
2463                                          HeapRegionClaimer *hrclaimer,
2464                                          bool concurrent) const {
2465   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2466 }
2467 
2468 // Clear the cached CSet starting regions and (more importantly)
2469 // the time stamps. Called when we reset the GC time stamp.
2470 void G1CollectedHeap::clear_cset_start_regions() {
2471   assert(_worker_cset_start_region != NULL, "sanity");
2472   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2473 
2474   for (uint i = 0; i < ParallelGCThreads; i++) {
2475     _worker_cset_start_region[i] = NULL;
2476     _worker_cset_start_region_time_stamp[i] = 0;
2477   }
2478 }
2479 
2480 // Given the id of a worker, obtain or calculate a suitable
2481 // starting region for iterating over the current collection set.
2482 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2483   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2484 
2485   HeapRegion* result = NULL;
2486   unsigned gc_time_stamp = get_gc_time_stamp();
2487 
2488   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2489     // Cached starting region for current worker was set
2490     // during the current pause - so it's valid.
2491     // Note: the cached starting heap region may be NULL
2492     // (when the collection set is empty).
2493     result = _worker_cset_start_region[worker_i];
2494     assert(result == NULL || result->in_collection_set(), "sanity");
2495     return result;
2496   }
2497 
2498   // The cached entry was not valid so let's calculate
2499   // a suitable starting heap region for this worker.
2500 
2501   // We want the parallel threads to start their collection
2502   // set iteration at different collection set regions to
2503   // avoid contention.
2504   // If we have:
2505   //          n collection set regions
2506   //          p threads
2507   // Then thread t will start at region floor ((t * n) / p)
2508 
2509   result = collection_set()->head();
2510   uint cs_size = collection_set()->region_length();
2511   uint active_workers = workers()->active_workers();
2512 
2513   uint end_ind   = (cs_size * worker_i) / active_workers;
2514   uint start_ind = 0;
2515 
2516   if (worker_i > 0 &&
2517       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2518     // Previous workers starting region is valid
2519     // so let's iterate from there
2520     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2521     OrderAccess::loadload();
2522     result = _worker_cset_start_region[worker_i - 1];
2523   }
2524 
2525   for (uint i = start_ind; i < end_ind; i++) {
2526     result = result->next_in_collection_set();
2527   }
2528 
2529   // Note: the calculated starting heap region may be NULL
2530   // (when the collection set is empty).
2531   assert(result == NULL || result->in_collection_set(), "sanity");
2532   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2533          "should be updated only once per pause");
2534   _worker_cset_start_region[worker_i] = result;
2535   OrderAccess::storestore();
2536   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2537   return result;
2538 }
2539 
2540 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2541   HeapRegion* r = collection_set()->head();
2542   while (r != NULL) {
2543     HeapRegion* next = r->next_in_collection_set();
2544     if (cl->doHeapRegion(r)) {
2545       cl->incomplete();
2546       return;
2547     }
2548     r = next;
2549   }
2550 }
2551 
2552 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2553                                                   HeapRegionClosure *cl) {
2554   if (r == NULL) {
2555     // The CSet is empty so there's nothing to do.
2556     return;
2557   }
2558 
2559   assert(r->in_collection_set(),
2560          "Start region must be a member of the collection set.");
2561   HeapRegion* cur = r;
2562   while (cur != NULL) {
2563     HeapRegion* next = cur->next_in_collection_set();
2564     if (cl->doHeapRegion(cur) && false) {
2565       cl->incomplete();
2566       return;
2567     }
2568     cur = next;
2569   }
2570   cur = collection_set()->head();
2571   while (cur != r) {
2572     HeapRegion* next = cur->next_in_collection_set();
2573     if (cl->doHeapRegion(cur) && false) {
2574       cl->incomplete();
2575       return;
2576     }
2577     cur = next;
2578   }
2579 }
2580 
2581 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2582   HeapRegion* result = _hrm.next_region_in_heap(from);
2583   while (result != NULL && result->is_pinned()) {
2584     result = _hrm.next_region_in_heap(result);
2585   }
2586   return result;
2587 }
2588 
2589 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2590   HeapRegion* hr = heap_region_containing(addr);
2591   return hr->block_start(addr);
2592 }
2593 
2594 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2595   HeapRegion* hr = heap_region_containing(addr);
2596   return hr->block_size(addr);
2597 }
2598 
2599 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2600   HeapRegion* hr = heap_region_containing(addr);
2601   return hr->block_is_obj(addr);
2602 }
2603 
2604 bool G1CollectedHeap::supports_tlab_allocation() const {
2605   return true;
2606 }
2607 
2608 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2609   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2610 }
2611 
2612 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2613   return young_list()->eden_used_bytes();
2614 }
2615 
2616 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2617 // must be equal to the humongous object limit.
2618 size_t G1CollectedHeap::max_tlab_size() const {
2619   return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2620 }
2621 
2622 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2623   AllocationContext_t context = AllocationContext::current();
2624   return _allocator->unsafe_max_tlab_alloc(context);
2625 }
2626 
2627 size_t G1CollectedHeap::max_capacity() const {
2628   return _hrm.reserved().byte_size();
2629 }
2630 
2631 jlong G1CollectedHeap::millis_since_last_gc() {
2632   // assert(false, "NYI");
2633   return 0;
2634 }
2635 
2636 void G1CollectedHeap::prepare_for_verify() {
2637   _verifier->prepare_for_verify();
2638 }
2639 
2640 void G1CollectedHeap::verify(VerifyOption vo) {
2641   _verifier->verify(vo);
2642 }
2643 
2644 class PrintRegionClosure: public HeapRegionClosure {
2645   outputStream* _st;
2646 public:
2647   PrintRegionClosure(outputStream* st) : _st(st) {}
2648   bool doHeapRegion(HeapRegion* r) {
2649     r->print_on(_st);
2650     return false;
2651   }
2652 };
2653 
2654 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2655                                        const HeapRegion* hr,
2656                                        const VerifyOption vo) const {
2657   switch (vo) {
2658   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2659   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2660   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
2661   default:                            ShouldNotReachHere();
2662   }
2663   return false; // keep some compilers happy
2664 }
2665 
2666 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2667                                        const VerifyOption vo) const {
2668   switch (vo) {
2669   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2670   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2671   case VerifyOption_G1UseMarkWord: {
2672     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2673     return !obj->is_gc_marked() && !hr->is_archive();
2674   }
2675   default:                            ShouldNotReachHere();
2676   }
2677   return false; // keep some compilers happy
2678 }
2679 
2680 void G1CollectedHeap::print_heap_regions() const {
2681   Log(gc, heap, region) log;
2682   if (log.is_trace()) {
2683     ResourceMark rm;
2684     print_regions_on(log.trace_stream());
2685   }
2686 }
2687 
2688 void G1CollectedHeap::print_on(outputStream* st) const {
2689   st->print(" %-20s", "garbage-first heap");
2690   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2691             capacity()/K, used_unlocked()/K);
2692   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2693             p2i(_hrm.reserved().start()),
2694             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2695             p2i(_hrm.reserved().end()));
2696   st->cr();
2697   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2698   uint young_regions = _young_list->length();
2699   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2700             (size_t) young_regions * HeapRegion::GrainBytes / K);
2701   uint survivor_regions = _young_list->survivor_length();
2702   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2703             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2704   st->cr();
2705   MetaspaceAux::print_on(st);
2706 }
2707 
2708 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2709   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2710                "HS=humongous(starts), HC=humongous(continues), "
2711                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2712                "AC=allocation context, "
2713                "TAMS=top-at-mark-start (previous, next)");
2714   PrintRegionClosure blk(st);
2715   heap_region_iterate(&blk);
2716 }
2717 
2718 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2719   print_on(st);
2720 
2721   // Print the per-region information.
2722   print_regions_on(st);
2723 }
2724 
2725 void G1CollectedHeap::print_on_error(outputStream* st) const {
2726   this->CollectedHeap::print_on_error(st);
2727 
2728   if (_cm != NULL) {
2729     st->cr();
2730     _cm->print_on_error(st);
2731   }
2732 }
2733 
2734 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2735   workers()->print_worker_threads_on(st);
2736   _cmThread->print_on(st);
2737   st->cr();
2738   _cm->print_worker_threads_on(st);
2739   _cg1r->print_worker_threads_on(st);
2740   if (G1StringDedup::is_enabled()) {
2741     G1StringDedup::print_worker_threads_on(st);
2742   }
2743 }
2744 
2745 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2746   workers()->threads_do(tc);
2747   tc->do_thread(_cmThread);
2748   _cg1r->threads_do(tc);
2749   if (G1StringDedup::is_enabled()) {
2750     G1StringDedup::threads_do(tc);
2751   }
2752 }
2753 
2754 void G1CollectedHeap::print_tracing_info() const {
2755   g1_rem_set()->print_summary_info();
2756   concurrent_mark()->print_summary_info();
2757   g1_policy()->print_yg_surv_rate_info();
2758 }
2759 
2760 #ifndef PRODUCT
2761 // Helpful for debugging RSet issues.
2762 
2763 class PrintRSetsClosure : public HeapRegionClosure {
2764 private:
2765   const char* _msg;
2766   size_t _occupied_sum;
2767 
2768 public:
2769   bool doHeapRegion(HeapRegion* r) {
2770     HeapRegionRemSet* hrrs = r->rem_set();
2771     size_t occupied = hrrs->occupied();
2772     _occupied_sum += occupied;
2773 
2774     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2775     if (occupied == 0) {
2776       tty->print_cr("  RSet is empty");
2777     } else {
2778       hrrs->print();
2779     }
2780     tty->print_cr("----------");
2781     return false;
2782   }
2783 
2784   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2785     tty->cr();
2786     tty->print_cr("========================================");
2787     tty->print_cr("%s", msg);
2788     tty->cr();
2789   }
2790 
2791   ~PrintRSetsClosure() {
2792     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2793     tty->print_cr("========================================");
2794     tty->cr();
2795   }
2796 };
2797 
2798 void G1CollectedHeap::print_cset_rsets() {
2799   PrintRSetsClosure cl("Printing CSet RSets");
2800   collection_set_iterate(&cl);
2801 }
2802 
2803 void G1CollectedHeap::print_all_rsets() {
2804   PrintRSetsClosure cl("Printing All RSets");;
2805   heap_region_iterate(&cl);
2806 }
2807 #endif // PRODUCT
2808 
2809 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2810   YoungList* young_list = heap()->young_list();
2811 
2812   size_t eden_used_bytes = young_list->eden_used_bytes();
2813   size_t survivor_used_bytes = young_list->survivor_used_bytes();
2814   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2815 
2816   size_t eden_capacity_bytes =
2817     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2818 
2819   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2820   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2821                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2822 }
2823 
2824 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2825   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2826                        stats->unused(), stats->used(), stats->region_end_waste(),
2827                        stats->regions_filled(), stats->direct_allocated(),
2828                        stats->failure_used(), stats->failure_waste());
2829 }
2830 
2831 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2832   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2833   gc_tracer->report_gc_heap_summary(when, heap_summary);
2834 
2835   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2836   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2837 }
2838 
2839 G1CollectedHeap* G1CollectedHeap::heap() {
2840   CollectedHeap* heap = Universe::heap();
2841   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2842   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2843   return (G1CollectedHeap*)heap;
2844 }
2845 
2846 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2847   // always_do_update_barrier = false;
2848   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2849   // Fill TLAB's and such
2850   accumulate_statistics_all_tlabs();
2851   ensure_parsability(true);
2852 
2853   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2854 }
2855 
2856 void G1CollectedHeap::gc_epilogue(bool full) {
2857   // we are at the end of the GC. Total collections has already been increased.
2858   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2859 
2860   // FIXME: what is this about?
2861   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2862   // is set.
2863 #if defined(COMPILER2) || INCLUDE_JVMCI
2864   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2865 #endif
2866   // always_do_update_barrier = true;
2867 
2868   resize_all_tlabs();
2869   allocation_context_stats().update(full);
2870 
2871   // We have just completed a GC. Update the soft reference
2872   // policy with the new heap occupancy
2873   Universe::update_heap_info_at_gc();
2874 }
2875 
2876 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2877                                                uint gc_count_before,
2878                                                bool* succeeded,
2879                                                GCCause::Cause gc_cause) {
2880   assert_heap_not_locked_and_not_at_safepoint();
2881   VM_G1IncCollectionPause op(gc_count_before,
2882                              word_size,
2883                              false, /* should_initiate_conc_mark */
2884                              g1_policy()->max_pause_time_ms(),
2885                              gc_cause);
2886 
2887   op.set_allocation_context(AllocationContext::current());
2888   VMThread::execute(&op);
2889 
2890   HeapWord* result = op.result();
2891   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2892   assert(result == NULL || ret_succeeded,
2893          "the result should be NULL if the VM did not succeed");
2894   *succeeded = ret_succeeded;
2895 
2896   assert_heap_not_locked();
2897   return result;
2898 }
2899 
2900 void
2901 G1CollectedHeap::doConcurrentMark() {
2902   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2903   if (!_cmThread->in_progress()) {
2904     _cmThread->set_started();
2905     CGC_lock->notify();
2906   }
2907 }
2908 
2909 size_t G1CollectedHeap::pending_card_num() {
2910   size_t extra_cards = 0;
2911   JavaThread *curr = Threads::first();
2912   while (curr != NULL) {
2913     DirtyCardQueue& dcq = curr->dirty_card_queue();
2914     extra_cards += dcq.size();
2915     curr = curr->next();
2916   }
2917   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2918   size_t buffer_size = dcqs.buffer_size();
2919   size_t buffer_num = dcqs.completed_buffers_num();
2920 
2921   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2922   // in bytes - not the number of 'entries'. We need to convert
2923   // into a number of cards.
2924   return (buffer_size * buffer_num + extra_cards) / oopSize;
2925 }
2926 
2927 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2928  private:
2929   size_t _total_humongous;
2930   size_t _candidate_humongous;
2931 
2932   DirtyCardQueue _dcq;
2933 
2934   // We don't nominate objects with many remembered set entries, on
2935   // the assumption that such objects are likely still live.
2936   bool is_remset_small(HeapRegion* region) const {
2937     HeapRegionRemSet* const rset = region->rem_set();
2938     return G1EagerReclaimHumongousObjectsWithStaleRefs
2939       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2940       : rset->is_empty();
2941   }
2942 
2943   bool is_typeArray_region(HeapRegion* region) const {
2944     return oop(region->bottom())->is_typeArray();
2945   }
2946 
2947   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2948     assert(region->is_starts_humongous(), "Must start a humongous object");
2949 
2950     // Candidate selection must satisfy the following constraints
2951     // while concurrent marking is in progress:
2952     //
2953     // * In order to maintain SATB invariants, an object must not be
2954     // reclaimed if it was allocated before the start of marking and
2955     // has not had its references scanned.  Such an object must have
2956     // its references (including type metadata) scanned to ensure no
2957     // live objects are missed by the marking process.  Objects
2958     // allocated after the start of concurrent marking don't need to
2959     // be scanned.
2960     //
2961     // * An object must not be reclaimed if it is on the concurrent
2962     // mark stack.  Objects allocated after the start of concurrent
2963     // marking are never pushed on the mark stack.
2964     //
2965     // Nominating only objects allocated after the start of concurrent
2966     // marking is sufficient to meet both constraints.  This may miss
2967     // some objects that satisfy the constraints, but the marking data
2968     // structures don't support efficiently performing the needed
2969     // additional tests or scrubbing of the mark stack.
2970     //
2971     // However, we presently only nominate is_typeArray() objects.
2972     // A humongous object containing references induces remembered
2973     // set entries on other regions.  In order to reclaim such an
2974     // object, those remembered sets would need to be cleaned up.
2975     //
2976     // We also treat is_typeArray() objects specially, allowing them
2977     // to be reclaimed even if allocated before the start of
2978     // concurrent mark.  For this we rely on mark stack insertion to
2979     // exclude is_typeArray() objects, preventing reclaiming an object
2980     // that is in the mark stack.  We also rely on the metadata for
2981     // such objects to be built-in and so ensured to be kept live.
2982     // Frequent allocation and drop of large binary blobs is an
2983     // important use case for eager reclaim, and this special handling
2984     // may reduce needed headroom.
2985 
2986     return is_typeArray_region(region) && is_remset_small(region);
2987   }
2988 
2989  public:
2990   RegisterHumongousWithInCSetFastTestClosure()
2991   : _total_humongous(0),
2992     _candidate_humongous(0),
2993     _dcq(&JavaThread::dirty_card_queue_set()) {
2994   }
2995 
2996   virtual bool doHeapRegion(HeapRegion* r) {
2997     if (!r->is_starts_humongous()) {
2998       return false;
2999     }
3000     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3001 
3002     bool is_candidate = humongous_region_is_candidate(g1h, r);
3003     uint rindex = r->hrm_index();
3004     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3005     if (is_candidate) {
3006       _candidate_humongous++;
3007       g1h->register_humongous_region_with_cset(rindex);
3008       // Is_candidate already filters out humongous object with large remembered sets.
3009       // If we have a humongous object with a few remembered sets, we simply flush these
3010       // remembered set entries into the DCQS. That will result in automatic
3011       // re-evaluation of their remembered set entries during the following evacuation
3012       // phase.
3013       if (!r->rem_set()->is_empty()) {
3014         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3015                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3016         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3017         HeapRegionRemSetIterator hrrs(r->rem_set());
3018         size_t card_index;
3019         while (hrrs.has_next(card_index)) {
3020           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3021           // The remembered set might contain references to already freed
3022           // regions. Filter out such entries to avoid failing card table
3023           // verification.
3024           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3025             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3026               *card_ptr = CardTableModRefBS::dirty_card_val();
3027               _dcq.enqueue(card_ptr);
3028             }
3029           }
3030         }
3031         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3032                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3033                hrrs.n_yielded(), r->rem_set()->occupied());
3034         r->rem_set()->clear_locked();
3035       }
3036       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3037     }
3038     _total_humongous++;
3039 
3040     return false;
3041   }
3042 
3043   size_t total_humongous() const { return _total_humongous; }
3044   size_t candidate_humongous() const { return _candidate_humongous; }
3045 
3046   void flush_rem_set_entries() { _dcq.flush(); }
3047 };
3048 
3049 void G1CollectedHeap::register_humongous_regions_with_cset() {
3050   if (!G1EagerReclaimHumongousObjects) {
3051     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3052     return;
3053   }
3054   double time = os::elapsed_counter();
3055 
3056   // Collect reclaim candidate information and register candidates with cset.
3057   RegisterHumongousWithInCSetFastTestClosure cl;
3058   heap_region_iterate(&cl);
3059 
3060   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3061   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3062                                                                   cl.total_humongous(),
3063                                                                   cl.candidate_humongous());
3064   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3065 
3066   // Finally flush all remembered set entries to re-check into the global DCQS.
3067   cl.flush_rem_set_entries();
3068 }
3069 
3070 class VerifyRegionRemSetClosure : public HeapRegionClosure {
3071   public:
3072     bool doHeapRegion(HeapRegion* hr) {
3073       if (!hr->is_archive() && !hr->is_continues_humongous()) {
3074         hr->verify_rem_set();
3075       }
3076       return false;
3077     }
3078 };
3079 
3080 #ifdef ASSERT
3081 class VerifyCSetClosure: public HeapRegionClosure {
3082 public:
3083   bool doHeapRegion(HeapRegion* hr) {
3084     // Here we check that the CSet region's RSet is ready for parallel
3085     // iteration. The fields that we'll verify are only manipulated
3086     // when the region is part of a CSet and is collected. Afterwards,
3087     // we reset these fields when we clear the region's RSet (when the
3088     // region is freed) so they are ready when the region is
3089     // re-allocated. The only exception to this is if there's an
3090     // evacuation failure and instead of freeing the region we leave
3091     // it in the heap. In that case, we reset these fields during
3092     // evacuation failure handling.
3093     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3094 
3095     // Here's a good place to add any other checks we'd like to
3096     // perform on CSet regions.
3097     return false;
3098   }
3099 };
3100 #endif // ASSERT
3101 
3102 uint G1CollectedHeap::num_task_queues() const {
3103   return _task_queues->size();
3104 }
3105 
3106 #if TASKQUEUE_STATS
3107 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3108   st->print_raw_cr("GC Task Stats");
3109   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3110   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3111 }
3112 
3113 void G1CollectedHeap::print_taskqueue_stats() const {
3114   if (!log_is_enabled(Trace, gc, task, stats)) {
3115     return;
3116   }
3117   Log(gc, task, stats) log;
3118   ResourceMark rm;
3119   outputStream* st = log.trace_stream();
3120 
3121   print_taskqueue_stats_hdr(st);
3122 
3123   TaskQueueStats totals;
3124   const uint n = num_task_queues();
3125   for (uint i = 0; i < n; ++i) {
3126     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3127     totals += task_queue(i)->stats;
3128   }
3129   st->print_raw("tot "); totals.print(st); st->cr();
3130 
3131   DEBUG_ONLY(totals.verify());
3132 }
3133 
3134 void G1CollectedHeap::reset_taskqueue_stats() {
3135   const uint n = num_task_queues();
3136   for (uint i = 0; i < n; ++i) {
3137     task_queue(i)->stats.reset();
3138   }
3139 }
3140 #endif // TASKQUEUE_STATS
3141 
3142 void G1CollectedHeap::wait_for_root_region_scanning() {
3143   double scan_wait_start = os::elapsedTime();
3144   // We have to wait until the CM threads finish scanning the
3145   // root regions as it's the only way to ensure that all the
3146   // objects on them have been correctly scanned before we start
3147   // moving them during the GC.
3148   bool waited = _cm->root_regions()->wait_until_scan_finished();
3149   double wait_time_ms = 0.0;
3150   if (waited) {
3151     double scan_wait_end = os::elapsedTime();
3152     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3153   }
3154   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3155 }
3156 
3157 bool
3158 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3159   assert_at_safepoint(true /* should_be_vm_thread */);
3160   guarantee(!is_gc_active(), "collection is not reentrant");
3161 
3162   if (GCLocker::check_active_before_gc()) {
3163     return false;
3164   }
3165 
3166   _gc_timer_stw->register_gc_start();
3167 
3168   GCIdMark gc_id_mark;
3169   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3170 
3171   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3172   ResourceMark rm;
3173 
3174   wait_for_root_region_scanning();
3175 
3176   print_heap_before_gc();
3177   print_heap_regions();
3178   trace_heap_before_gc(_gc_tracer_stw);
3179 
3180   _verifier->verify_region_sets_optional();
3181   _verifier->verify_dirty_young_regions();
3182 
3183   // We should not be doing initial mark unless the conc mark thread is running
3184   if (!_cmThread->should_terminate()) {
3185     // This call will decide whether this pause is an initial-mark
3186     // pause. If it is, during_initial_mark_pause() will return true
3187     // for the duration of this pause.
3188     g1_policy()->decide_on_conc_mark_initiation();
3189   }
3190 
3191   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3192   assert(!collector_state()->during_initial_mark_pause() ||
3193           collector_state()->gcs_are_young(), "sanity");
3194 
3195   // We also do not allow mixed GCs during marking.
3196   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3197 
3198   // Record whether this pause is an initial mark. When the current
3199   // thread has completed its logging output and it's safe to signal
3200   // the CM thread, the flag's value in the policy has been reset.
3201   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3202 
3203   // Inner scope for scope based logging, timers, and stats collection
3204   {
3205     EvacuationInfo evacuation_info;
3206 
3207     if (collector_state()->during_initial_mark_pause()) {
3208       // We are about to start a marking cycle, so we increment the
3209       // full collection counter.
3210       increment_old_marking_cycles_started();
3211       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3212     }
3213 
3214     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3215 
3216     GCTraceCPUTime tcpu;
3217 
3218     FormatBuffer<> gc_string("Pause ");
3219     if (collector_state()->during_initial_mark_pause()) {
3220       gc_string.append("Initial Mark");
3221     } else if (collector_state()->gcs_are_young()) {
3222       gc_string.append("Young");
3223     } else {
3224       gc_string.append("Mixed");
3225     }
3226     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3227 
3228     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3229                                                                   workers()->active_workers(),
3230                                                                   Threads::number_of_non_daemon_threads());
3231     workers()->set_active_workers(active_workers);
3232 
3233     g1_policy()->note_gc_start();
3234 
3235     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3236     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3237 
3238     // If the secondary_free_list is not empty, append it to the
3239     // free_list. No need to wait for the cleanup operation to finish;
3240     // the region allocation code will check the secondary_free_list
3241     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3242     // set, skip this step so that the region allocation code has to
3243     // get entries from the secondary_free_list.
3244     if (!G1StressConcRegionFreeing) {
3245       append_secondary_free_list_if_not_empty_with_lock();
3246     }
3247 
3248     G1HeapTransition heap_transition(this);
3249     size_t heap_used_bytes_before_gc = used();
3250 
3251     assert(check_young_list_well_formed(), "young list should be well formed");
3252 
3253     // Don't dynamically change the number of GC threads this early.  A value of
3254     // 0 is used to indicate serial work.  When parallel work is done,
3255     // it will be set.
3256 
3257     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3258       IsGCActiveMark x;
3259 
3260       gc_prologue(false);
3261       increment_total_collections(false /* full gc */);
3262       increment_gc_time_stamp();
3263 
3264       if (VerifyRememberedSets) {
3265         log_info(gc, verify)("[Verifying RemSets before GC]");
3266         VerifyRegionRemSetClosure v_cl;
3267         heap_region_iterate(&v_cl);
3268       }
3269 
3270       _verifier->verify_before_gc();
3271 
3272       _verifier->check_bitmaps("GC Start");
3273 
3274 #if defined(COMPILER2) || INCLUDE_JVMCI
3275       DerivedPointerTable::clear();
3276 #endif
3277 
3278       // Please see comment in g1CollectedHeap.hpp and
3279       // G1CollectedHeap::ref_processing_init() to see how
3280       // reference processing currently works in G1.
3281 
3282       // Enable discovery in the STW reference processor
3283       if (g1_policy()->should_process_references()) {
3284         ref_processor_stw()->enable_discovery();
3285       } else {
3286         ref_processor_stw()->disable_discovery();
3287       }
3288 
3289       {
3290         // We want to temporarily turn off discovery by the
3291         // CM ref processor, if necessary, and turn it back on
3292         // on again later if we do. Using a scoped
3293         // NoRefDiscovery object will do this.
3294         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3295 
3296         // Forget the current alloc region (we might even choose it to be part
3297         // of the collection set!).
3298         _allocator->release_mutator_alloc_region();
3299 
3300         // This timing is only used by the ergonomics to handle our pause target.
3301         // It is unclear why this should not include the full pause. We will
3302         // investigate this in CR 7178365.
3303         //
3304         // Preserving the old comment here if that helps the investigation:
3305         //
3306         // The elapsed time induced by the start time below deliberately elides
3307         // the possible verification above.
3308         double sample_start_time_sec = os::elapsedTime();
3309 
3310         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3311 
3312         if (collector_state()->during_initial_mark_pause()) {
3313           concurrent_mark()->checkpointRootsInitialPre();
3314         }
3315 
3316         g1_policy()->finalize_collection_set(target_pause_time_ms);
3317 
3318         evacuation_info.set_collectionset_regions(collection_set()->region_length());
3319 
3320         // Make sure the remembered sets are up to date. This needs to be
3321         // done before register_humongous_regions_with_cset(), because the
3322         // remembered sets are used there to choose eager reclaim candidates.
3323         // If the remembered sets are not up to date we might miss some
3324         // entries that need to be handled.
3325         g1_rem_set()->cleanupHRRS();
3326 
3327         register_humongous_regions_with_cset();
3328 
3329         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3330 
3331         _cm->note_start_of_gc();
3332         // We call this after finalize_cset() to
3333         // ensure that the CSet has been finalized.
3334         _cm->verify_no_cset_oops();
3335 
3336         if (_hr_printer.is_active()) {
3337           HeapRegion* hr = collection_set()->head();
3338           while (hr != NULL) {
3339             _hr_printer.cset(hr);
3340             hr = hr->next_in_collection_set();
3341           }
3342         }
3343 
3344 #ifdef ASSERT
3345         VerifyCSetClosure cl;
3346         collection_set_iterate(&cl);
3347 #endif // ASSERT
3348 
3349         // Initialize the GC alloc regions.
3350         _allocator->init_gc_alloc_regions(evacuation_info);
3351 
3352         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3353         pre_evacuate_collection_set();
3354 
3355         // Actually do the work...
3356         evacuate_collection_set(evacuation_info, &per_thread_states);
3357 
3358         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3359 
3360         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3361         free_collection_set(collection_set()->head(), evacuation_info, surviving_young_words);
3362 
3363         eagerly_reclaim_humongous_regions();
3364 
3365         collection_set()->clear_head();
3366 
3367         record_obj_copy_mem_stats();
3368         _survivor_evac_stats.adjust_desired_plab_sz();
3369         _old_evac_stats.adjust_desired_plab_sz();
3370 
3371         // Start a new incremental collection set for the next pause.
3372         collection_set()->start_incremental_building();
3373 
3374         clear_cset_fast_test();
3375 
3376         // Don't check the whole heap at this point as the
3377         // GC alloc regions from this pause have been tagged
3378         // as survivors and moved on to the survivor list.
3379         // Survivor regions will fail the !is_young() check.
3380         assert(check_young_list_empty(false /* check_heap */),
3381           "young list should be empty");
3382 
3383         _young_list->reset_auxilary_lists();
3384 
3385         if (evacuation_failed()) {
3386           set_used(recalculate_used());
3387           if (_archive_allocator != NULL) {
3388             _archive_allocator->clear_used();
3389           }
3390           for (uint i = 0; i < ParallelGCThreads; i++) {
3391             if (_evacuation_failed_info_array[i].has_failed()) {
3392               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3393             }
3394           }
3395         } else {
3396           // The "used" of the the collection set have already been subtracted
3397           // when they were freed.  Add in the bytes evacuated.
3398           increase_used(g1_policy()->bytes_copied_during_gc());
3399         }
3400 
3401         if (collector_state()->during_initial_mark_pause()) {
3402           // We have to do this before we notify the CM threads that
3403           // they can start working to make sure that all the
3404           // appropriate initialization is done on the CM object.
3405           concurrent_mark()->checkpointRootsInitialPost();
3406           collector_state()->set_mark_in_progress(true);
3407           // Note that we don't actually trigger the CM thread at
3408           // this point. We do that later when we're sure that
3409           // the current thread has completed its logging output.
3410         }
3411 
3412         allocate_dummy_regions();
3413 
3414         _allocator->init_mutator_alloc_region();
3415 
3416         {
3417           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3418           if (expand_bytes > 0) {
3419             size_t bytes_before = capacity();
3420             // No need for an ergo logging here,
3421             // expansion_amount() does this when it returns a value > 0.
3422             double expand_ms;
3423             if (!expand(expand_bytes, &expand_ms)) {
3424               // We failed to expand the heap. Cannot do anything about it.
3425             }
3426             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3427           }
3428         }
3429 
3430         // We redo the verification but now wrt to the new CSet which
3431         // has just got initialized after the previous CSet was freed.
3432         _cm->verify_no_cset_oops();
3433         _cm->note_end_of_gc();
3434 
3435         // This timing is only used by the ergonomics to handle our pause target.
3436         // It is unclear why this should not include the full pause. We will
3437         // investigate this in CR 7178365.
3438         double sample_end_time_sec = os::elapsedTime();
3439         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3440         size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3441         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3442 
3443         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3444         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3445 
3446         MemoryService::track_memory_usage();
3447 
3448         // In prepare_for_verify() below we'll need to scan the deferred
3449         // update buffers to bring the RSets up-to-date if
3450         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3451         // the update buffers we'll probably need to scan cards on the
3452         // regions we just allocated to (i.e., the GC alloc
3453         // regions). However, during the last GC we called
3454         // set_saved_mark() on all the GC alloc regions, so card
3455         // scanning might skip the [saved_mark_word()...top()] area of
3456         // those regions (i.e., the area we allocated objects into
3457         // during the last GC). But it shouldn't. Given that
3458         // saved_mark_word() is conditional on whether the GC time stamp
3459         // on the region is current or not, by incrementing the GC time
3460         // stamp here we invalidate all the GC time stamps on all the
3461         // regions and saved_mark_word() will simply return top() for
3462         // all the regions. This is a nicer way of ensuring this rather
3463         // than iterating over the regions and fixing them. In fact, the
3464         // GC time stamp increment here also ensures that
3465         // saved_mark_word() will return top() between pauses, i.e.,
3466         // during concurrent refinement. So we don't need the
3467         // is_gc_active() check to decided which top to use when
3468         // scanning cards (see CR 7039627).
3469         increment_gc_time_stamp();
3470 
3471         if (VerifyRememberedSets) {
3472           log_info(gc, verify)("[Verifying RemSets after GC]");
3473           VerifyRegionRemSetClosure v_cl;
3474           heap_region_iterate(&v_cl);
3475         }
3476 
3477         _verifier->verify_after_gc();
3478         _verifier->check_bitmaps("GC End");
3479 
3480         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3481         ref_processor_stw()->verify_no_references_recorded();
3482 
3483         // CM reference discovery will be re-enabled if necessary.
3484       }
3485 
3486 #ifdef TRACESPINNING
3487       ParallelTaskTerminator::print_termination_counts();
3488 #endif
3489 
3490       gc_epilogue(false);
3491     }
3492 
3493     // Print the remainder of the GC log output.
3494     if (evacuation_failed()) {
3495       log_info(gc)("To-space exhausted");
3496     }
3497 
3498     g1_policy()->print_phases();
3499     heap_transition.print();
3500 
3501     // It is not yet to safe to tell the concurrent mark to
3502     // start as we have some optional output below. We don't want the
3503     // output from the concurrent mark thread interfering with this
3504     // logging output either.
3505 
3506     _hrm.verify_optional();
3507     _verifier->verify_region_sets_optional();
3508 
3509     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3510     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3511 
3512     print_heap_after_gc();
3513     print_heap_regions();
3514     trace_heap_after_gc(_gc_tracer_stw);
3515 
3516     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3517     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3518     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3519     // before any GC notifications are raised.
3520     g1mm()->update_sizes();
3521 
3522     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3523     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3524     _gc_timer_stw->register_gc_end();
3525     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3526   }
3527   // It should now be safe to tell the concurrent mark thread to start
3528   // without its logging output interfering with the logging output
3529   // that came from the pause.
3530 
3531   if (should_start_conc_mark) {
3532     // CAUTION: after the doConcurrentMark() call below,
3533     // the concurrent marking thread(s) could be running
3534     // concurrently with us. Make sure that anything after
3535     // this point does not assume that we are the only GC thread
3536     // running. Note: of course, the actual marking work will
3537     // not start until the safepoint itself is released in
3538     // SuspendibleThreadSet::desynchronize().
3539     doConcurrentMark();
3540   }
3541 
3542   return true;
3543 }
3544 
3545 void G1CollectedHeap::restore_preserved_marks() {
3546   G1RestorePreservedMarksTask rpm_task(_preserved_objs);
3547   workers()->run_task(&rpm_task);
3548 }
3549 
3550 void G1CollectedHeap::remove_self_forwarding_pointers() {
3551   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3552   workers()->run_task(&rsfp_task);
3553 }
3554 
3555 void G1CollectedHeap::restore_after_evac_failure() {
3556   double remove_self_forwards_start = os::elapsedTime();
3557 
3558   remove_self_forwarding_pointers();
3559   restore_preserved_marks();
3560 
3561   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3562 }
3563 
3564 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3565   if (!_evacuation_failed) {
3566     _evacuation_failed = true;
3567   }
3568 
3569   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3570 
3571   // We want to call the "for_promotion_failure" version only in the
3572   // case of a promotion failure.
3573   if (m->must_be_preserved_for_promotion_failure(obj)) {
3574     OopAndMarkOop elem(obj, m);
3575     _preserved_objs[worker_id].push(elem);
3576   }
3577 }
3578 
3579 bool G1ParEvacuateFollowersClosure::offer_termination() {
3580   G1ParScanThreadState* const pss = par_scan_state();
3581   start_term_time();
3582   const bool res = terminator()->offer_termination();
3583   end_term_time();
3584   return res;
3585 }
3586 
3587 void G1ParEvacuateFollowersClosure::do_void() {
3588   G1ParScanThreadState* const pss = par_scan_state();
3589   pss->trim_queue();
3590   do {
3591     pss->steal_and_trim_queue(queues());
3592   } while (!offer_termination());
3593 }
3594 
3595 class G1ParTask : public AbstractGangTask {
3596 protected:
3597   G1CollectedHeap*         _g1h;
3598   G1ParScanThreadStateSet* _pss;
3599   RefToScanQueueSet*       _queues;
3600   G1RootProcessor*         _root_processor;
3601   ParallelTaskTerminator   _terminator;
3602   uint                     _n_workers;
3603 
3604 public:
3605   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3606     : AbstractGangTask("G1 collection"),
3607       _g1h(g1h),
3608       _pss(per_thread_states),
3609       _queues(task_queues),
3610       _root_processor(root_processor),
3611       _terminator(n_workers, _queues),
3612       _n_workers(n_workers)
3613   {}
3614 
3615   void work(uint worker_id) {
3616     if (worker_id >= _n_workers) return;  // no work needed this round
3617 
3618     double start_sec = os::elapsedTime();
3619     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3620 
3621     {
3622       ResourceMark rm;
3623       HandleMark   hm;
3624 
3625       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3626 
3627       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3628       pss->set_ref_processor(rp);
3629 
3630       double start_strong_roots_sec = os::elapsedTime();
3631 
3632       _root_processor->evacuate_roots(pss->closures(), worker_id);
3633 
3634       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3635 
3636       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3637       // treating the nmethods visited to act as roots for concurrent marking.
3638       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3639       // objects copied by the current evacuation.
3640       size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3641                                                                              pss->closures()->weak_codeblobs(),
3642                                                                              worker_id);
3643 
3644       _pss->add_cards_scanned(worker_id, cards_scanned);
3645 
3646       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3647 
3648       double term_sec = 0.0;
3649       size_t evac_term_attempts = 0;
3650       {
3651         double start = os::elapsedTime();
3652         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3653         evac.do_void();
3654 
3655         evac_term_attempts = evac.term_attempts();
3656         term_sec = evac.term_time();
3657         double elapsed_sec = os::elapsedTime() - start;
3658         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3659         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3660         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3661       }
3662 
3663       assert(pss->queue_is_empty(), "should be empty");
3664 
3665       if (log_is_enabled(Debug, gc, task, stats)) {
3666         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3667         size_t lab_waste;
3668         size_t lab_undo_waste;
3669         pss->waste(lab_waste, lab_undo_waste);
3670         _g1h->print_termination_stats(worker_id,
3671                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3672                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3673                                       term_sec * 1000.0,                          /* evac term time */
3674                                       evac_term_attempts,                         /* evac term attempts */
3675                                       lab_waste,                                  /* alloc buffer waste */
3676                                       lab_undo_waste                              /* undo waste */
3677                                       );
3678       }
3679 
3680       // Close the inner scope so that the ResourceMark and HandleMark
3681       // destructors are executed here and are included as part of the
3682       // "GC Worker Time".
3683     }
3684     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3685   }
3686 };
3687 
3688 void G1CollectedHeap::print_termination_stats_hdr() {
3689   log_debug(gc, task, stats)("GC Termination Stats");
3690   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3691   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3692   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3693 }
3694 
3695 void G1CollectedHeap::print_termination_stats(uint worker_id,
3696                                               double elapsed_ms,
3697                                               double strong_roots_ms,
3698                                               double term_ms,
3699                                               size_t term_attempts,
3700                                               size_t alloc_buffer_waste,
3701                                               size_t undo_waste) const {
3702   log_debug(gc, task, stats)
3703               ("%3d %9.2f %9.2f %6.2f "
3704                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3705                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3706                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3707                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3708                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3709                alloc_buffer_waste * HeapWordSize / K,
3710                undo_waste * HeapWordSize / K);
3711 }
3712 
3713 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3714 private:
3715   BoolObjectClosure* _is_alive;
3716   int _initial_string_table_size;
3717   int _initial_symbol_table_size;
3718 
3719   bool  _process_strings;
3720   int _strings_processed;
3721   int _strings_removed;
3722 
3723   bool  _process_symbols;
3724   int _symbols_processed;
3725   int _symbols_removed;
3726 
3727 public:
3728   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3729     AbstractGangTask("String/Symbol Unlinking"),
3730     _is_alive(is_alive),
3731     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3732     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3733 
3734     _initial_string_table_size = StringTable::the_table()->table_size();
3735     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3736     if (process_strings) {
3737       StringTable::clear_parallel_claimed_index();
3738     }
3739     if (process_symbols) {
3740       SymbolTable::clear_parallel_claimed_index();
3741     }
3742   }
3743 
3744   ~G1StringSymbolTableUnlinkTask() {
3745     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3746               "claim value %d after unlink less than initial string table size %d",
3747               StringTable::parallel_claimed_index(), _initial_string_table_size);
3748     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3749               "claim value %d after unlink less than initial symbol table size %d",
3750               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3751 
3752     log_info(gc, stringtable)(
3753         "Cleaned string and symbol table, "
3754         "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3755         "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3756         strings_processed(), strings_removed(),
3757         symbols_processed(), symbols_removed());
3758   }
3759 
3760   void work(uint worker_id) {
3761     int strings_processed = 0;
3762     int strings_removed = 0;
3763     int symbols_processed = 0;
3764     int symbols_removed = 0;
3765     if (_process_strings) {
3766       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3767       Atomic::add(strings_processed, &_strings_processed);
3768       Atomic::add(strings_removed, &_strings_removed);
3769     }
3770     if (_process_symbols) {
3771       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3772       Atomic::add(symbols_processed, &_symbols_processed);
3773       Atomic::add(symbols_removed, &_symbols_removed);
3774     }
3775   }
3776 
3777   size_t strings_processed() const { return (size_t)_strings_processed; }
3778   size_t strings_removed()   const { return (size_t)_strings_removed; }
3779 
3780   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3781   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3782 };
3783 
3784 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3785 private:
3786   static Monitor* _lock;
3787 
3788   BoolObjectClosure* const _is_alive;
3789   const bool               _unloading_occurred;
3790   const uint               _num_workers;
3791 
3792   // Variables used to claim nmethods.
3793   nmethod* _first_nmethod;
3794   volatile nmethod* _claimed_nmethod;
3795 
3796   // The list of nmethods that need to be processed by the second pass.
3797   volatile nmethod* _postponed_list;
3798   volatile uint     _num_entered_barrier;
3799 
3800  public:
3801   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3802       _is_alive(is_alive),
3803       _unloading_occurred(unloading_occurred),
3804       _num_workers(num_workers),
3805       _first_nmethod(NULL),
3806       _claimed_nmethod(NULL),
3807       _postponed_list(NULL),
3808       _num_entered_barrier(0)
3809   {
3810     nmethod::increase_unloading_clock();
3811     // Get first alive nmethod
3812     NMethodIterator iter = NMethodIterator();
3813     if(iter.next_alive()) {
3814       _first_nmethod = iter.method();
3815     }
3816     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
3817   }
3818 
3819   ~G1CodeCacheUnloadingTask() {
3820     CodeCache::verify_clean_inline_caches();
3821 
3822     CodeCache::set_needs_cache_clean(false);
3823     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3824 
3825     CodeCache::verify_icholder_relocations();
3826   }
3827 
3828  private:
3829   void add_to_postponed_list(nmethod* nm) {
3830       nmethod* old;
3831       do {
3832         old = (nmethod*)_postponed_list;
3833         nm->set_unloading_next(old);
3834       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3835   }
3836 
3837   void clean_nmethod(nmethod* nm) {
3838     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3839 
3840     if (postponed) {
3841       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3842       add_to_postponed_list(nm);
3843     }
3844 
3845     // Mark that this thread has been cleaned/unloaded.
3846     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3847     nm->set_unloading_clock(nmethod::global_unloading_clock());
3848   }
3849 
3850   void clean_nmethod_postponed(nmethod* nm) {
3851     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3852   }
3853 
3854   static const int MaxClaimNmethods = 16;
3855 
3856   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
3857     nmethod* first;
3858     NMethodIterator last;
3859 
3860     do {
3861       *num_claimed_nmethods = 0;
3862 
3863       first = (nmethod*)_claimed_nmethod;
3864       last = NMethodIterator(first);
3865 
3866       if (first != NULL) {
3867 
3868         for (int i = 0; i < MaxClaimNmethods; i++) {
3869           if (!last.next_alive()) {
3870             break;
3871           }
3872           claimed_nmethods[i] = last.method();
3873           (*num_claimed_nmethods)++;
3874         }
3875       }
3876 
3877     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3878   }
3879 
3880   nmethod* claim_postponed_nmethod() {
3881     nmethod* claim;
3882     nmethod* next;
3883 
3884     do {
3885       claim = (nmethod*)_postponed_list;
3886       if (claim == NULL) {
3887         return NULL;
3888       }
3889 
3890       next = claim->unloading_next();
3891 
3892     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3893 
3894     return claim;
3895   }
3896 
3897  public:
3898   // Mark that we're done with the first pass of nmethod cleaning.
3899   void barrier_mark(uint worker_id) {
3900     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3901     _num_entered_barrier++;
3902     if (_num_entered_barrier == _num_workers) {
3903       ml.notify_all();
3904     }
3905   }
3906 
3907   // See if we have to wait for the other workers to
3908   // finish their first-pass nmethod cleaning work.
3909   void barrier_wait(uint worker_id) {
3910     if (_num_entered_barrier < _num_workers) {
3911       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3912       while (_num_entered_barrier < _num_workers) {
3913           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3914       }
3915     }
3916   }
3917 
3918   // Cleaning and unloading of nmethods. Some work has to be postponed
3919   // to the second pass, when we know which nmethods survive.
3920   void work_first_pass(uint worker_id) {
3921     // The first nmethods is claimed by the first worker.
3922     if (worker_id == 0 && _first_nmethod != NULL) {
3923       clean_nmethod(_first_nmethod);
3924       _first_nmethod = NULL;
3925     }
3926 
3927     int num_claimed_nmethods;
3928     nmethod* claimed_nmethods[MaxClaimNmethods];
3929 
3930     while (true) {
3931       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3932 
3933       if (num_claimed_nmethods == 0) {
3934         break;
3935       }
3936 
3937       for (int i = 0; i < num_claimed_nmethods; i++) {
3938         clean_nmethod(claimed_nmethods[i]);
3939       }
3940     }
3941   }
3942 
3943   void work_second_pass(uint worker_id) {
3944     nmethod* nm;
3945     // Take care of postponed nmethods.
3946     while ((nm = claim_postponed_nmethod()) != NULL) {
3947       clean_nmethod_postponed(nm);
3948     }
3949   }
3950 };
3951 
3952 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3953 
3954 class G1KlassCleaningTask : public StackObj {
3955   BoolObjectClosure*                      _is_alive;
3956   volatile jint                           _clean_klass_tree_claimed;
3957   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3958 
3959  public:
3960   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3961       _is_alive(is_alive),
3962       _clean_klass_tree_claimed(0),
3963       _klass_iterator() {
3964   }
3965 
3966  private:
3967   bool claim_clean_klass_tree_task() {
3968     if (_clean_klass_tree_claimed) {
3969       return false;
3970     }
3971 
3972     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3973   }
3974 
3975   InstanceKlass* claim_next_klass() {
3976     Klass* klass;
3977     do {
3978       klass =_klass_iterator.next_klass();
3979     } while (klass != NULL && !klass->is_instance_klass());
3980 
3981     // this can be null so don't call InstanceKlass::cast
3982     return static_cast<InstanceKlass*>(klass);
3983   }
3984 
3985 public:
3986 
3987   void clean_klass(InstanceKlass* ik) {
3988     ik->clean_weak_instanceklass_links(_is_alive);
3989   }
3990 
3991   void work() {
3992     ResourceMark rm;
3993 
3994     // One worker will clean the subklass/sibling klass tree.
3995     if (claim_clean_klass_tree_task()) {
3996       Klass::clean_subklass_tree(_is_alive);
3997     }
3998 
3999     // All workers will help cleaning the classes,
4000     InstanceKlass* klass;
4001     while ((klass = claim_next_klass()) != NULL) {
4002       clean_klass(klass);
4003     }
4004   }
4005 };
4006 
4007 // To minimize the remark pause times, the tasks below are done in parallel.
4008 class G1ParallelCleaningTask : public AbstractGangTask {
4009 private:
4010   G1StringSymbolTableUnlinkTask _string_symbol_task;
4011   G1CodeCacheUnloadingTask      _code_cache_task;
4012   G1KlassCleaningTask           _klass_cleaning_task;
4013 
4014 public:
4015   // The constructor is run in the VMThread.
4016   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4017       AbstractGangTask("Parallel Cleaning"),
4018       _string_symbol_task(is_alive, process_strings, process_symbols),
4019       _code_cache_task(num_workers, is_alive, unloading_occurred),
4020       _klass_cleaning_task(is_alive) {
4021   }
4022 
4023   // The parallel work done by all worker threads.
4024   void work(uint worker_id) {
4025     // Do first pass of code cache cleaning.
4026     _code_cache_task.work_first_pass(worker_id);
4027 
4028     // Let the threads mark that the first pass is done.
4029     _code_cache_task.barrier_mark(worker_id);
4030 
4031     // Clean the Strings and Symbols.
4032     _string_symbol_task.work(worker_id);
4033 
4034     // Wait for all workers to finish the first code cache cleaning pass.
4035     _code_cache_task.barrier_wait(worker_id);
4036 
4037     // Do the second code cache cleaning work, which realize on
4038     // the liveness information gathered during the first pass.
4039     _code_cache_task.work_second_pass(worker_id);
4040 
4041     // Clean all klasses that were not unloaded.
4042     _klass_cleaning_task.work();
4043   }
4044 };
4045 
4046 
4047 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4048                                         bool process_strings,
4049                                         bool process_symbols,
4050                                         bool class_unloading_occurred) {
4051   uint n_workers = workers()->active_workers();
4052 
4053   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4054                                         n_workers, class_unloading_occurred);
4055   workers()->run_task(&g1_unlink_task);
4056 }
4057 
4058 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4059                                                      bool process_strings, bool process_symbols) {
4060   { // Timing scope
4061     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4062     workers()->run_task(&g1_unlink_task);
4063   }
4064 }
4065 
4066 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4067  private:
4068   DirtyCardQueueSet* _queue;
4069   G1CollectedHeap* _g1h;
4070  public:
4071   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4072     _queue(queue), _g1h(g1h) { }
4073 
4074   virtual void work(uint worker_id) {
4075     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4076     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4077 
4078     RedirtyLoggedCardTableEntryClosure cl(_g1h);
4079     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4080 
4081     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4082   }
4083 };
4084 
4085 void G1CollectedHeap::redirty_logged_cards() {
4086   double redirty_logged_cards_start = os::elapsedTime();
4087 
4088   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4089   dirty_card_queue_set().reset_for_par_iteration();
4090   workers()->run_task(&redirty_task);
4091 
4092   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4093   dcq.merge_bufferlists(&dirty_card_queue_set());
4094   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4095 
4096   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4097 }
4098 
4099 // Weak Reference Processing support
4100 
4101 // An always "is_alive" closure that is used to preserve referents.
4102 // If the object is non-null then it's alive.  Used in the preservation
4103 // of referent objects that are pointed to by reference objects
4104 // discovered by the CM ref processor.
4105 class G1AlwaysAliveClosure: public BoolObjectClosure {
4106   G1CollectedHeap* _g1;
4107 public:
4108   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4109   bool do_object_b(oop p) {
4110     if (p != NULL) {
4111       return true;
4112     }
4113     return false;
4114   }
4115 };
4116 
4117 bool G1STWIsAliveClosure::do_object_b(oop p) {
4118   // An object is reachable if it is outside the collection set,
4119   // or is inside and copied.
4120   return !_g1->is_in_cset(p) || p->is_forwarded();
4121 }
4122 
4123 // Non Copying Keep Alive closure
4124 class G1KeepAliveClosure: public OopClosure {
4125   G1CollectedHeap* _g1;
4126 public:
4127   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4128   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4129   void do_oop(oop* p) {
4130     oop obj = *p;
4131     assert(obj != NULL, "the caller should have filtered out NULL values");
4132 
4133     const InCSetState cset_state = _g1->in_cset_state(obj);
4134     if (!cset_state.is_in_cset_or_humongous()) {
4135       return;
4136     }
4137     if (cset_state.is_in_cset()) {
4138       assert( obj->is_forwarded(), "invariant" );
4139       *p = obj->forwardee();
4140     } else {
4141       assert(!obj->is_forwarded(), "invariant" );
4142       assert(cset_state.is_humongous(),
4143              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4144       _g1->set_humongous_is_live(obj);
4145     }
4146   }
4147 };
4148 
4149 // Copying Keep Alive closure - can be called from both
4150 // serial and parallel code as long as different worker
4151 // threads utilize different G1ParScanThreadState instances
4152 // and different queues.
4153 
4154 class G1CopyingKeepAliveClosure: public OopClosure {
4155   G1CollectedHeap*         _g1h;
4156   OopClosure*              _copy_non_heap_obj_cl;
4157   G1ParScanThreadState*    _par_scan_state;
4158 
4159 public:
4160   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4161                             OopClosure* non_heap_obj_cl,
4162                             G1ParScanThreadState* pss):
4163     _g1h(g1h),
4164     _copy_non_heap_obj_cl(non_heap_obj_cl),
4165     _par_scan_state(pss)
4166   {}
4167 
4168   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4169   virtual void do_oop(      oop* p) { do_oop_work(p); }
4170 
4171   template <class T> void do_oop_work(T* p) {
4172     oop obj = oopDesc::load_decode_heap_oop(p);
4173 
4174     if (_g1h->is_in_cset_or_humongous(obj)) {
4175       // If the referent object has been forwarded (either copied
4176       // to a new location or to itself in the event of an
4177       // evacuation failure) then we need to update the reference
4178       // field and, if both reference and referent are in the G1
4179       // heap, update the RSet for the referent.
4180       //
4181       // If the referent has not been forwarded then we have to keep
4182       // it alive by policy. Therefore we have copy the referent.
4183       //
4184       // If the reference field is in the G1 heap then we can push
4185       // on the PSS queue. When the queue is drained (after each
4186       // phase of reference processing) the object and it's followers
4187       // will be copied, the reference field set to point to the
4188       // new location, and the RSet updated. Otherwise we need to
4189       // use the the non-heap or metadata closures directly to copy
4190       // the referent object and update the pointer, while avoiding
4191       // updating the RSet.
4192 
4193       if (_g1h->is_in_g1_reserved(p)) {
4194         _par_scan_state->push_on_queue(p);
4195       } else {
4196         assert(!Metaspace::contains((const void*)p),
4197                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4198         _copy_non_heap_obj_cl->do_oop(p);
4199       }
4200     }
4201   }
4202 };
4203 
4204 // Serial drain queue closure. Called as the 'complete_gc'
4205 // closure for each discovered list in some of the
4206 // reference processing phases.
4207 
4208 class G1STWDrainQueueClosure: public VoidClosure {
4209 protected:
4210   G1CollectedHeap* _g1h;
4211   G1ParScanThreadState* _par_scan_state;
4212 
4213   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4214 
4215 public:
4216   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4217     _g1h(g1h),
4218     _par_scan_state(pss)
4219   { }
4220 
4221   void do_void() {
4222     G1ParScanThreadState* const pss = par_scan_state();
4223     pss->trim_queue();
4224   }
4225 };
4226 
4227 // Parallel Reference Processing closures
4228 
4229 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4230 // processing during G1 evacuation pauses.
4231 
4232 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4233 private:
4234   G1CollectedHeap*          _g1h;
4235   G1ParScanThreadStateSet*  _pss;
4236   RefToScanQueueSet*        _queues;
4237   WorkGang*                 _workers;
4238   uint                      _active_workers;
4239 
4240 public:
4241   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4242                            G1ParScanThreadStateSet* per_thread_states,
4243                            WorkGang* workers,
4244                            RefToScanQueueSet *task_queues,
4245                            uint n_workers) :
4246     _g1h(g1h),
4247     _pss(per_thread_states),
4248     _queues(task_queues),
4249     _workers(workers),
4250     _active_workers(n_workers)
4251   {
4252     g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4253   }
4254 
4255   // Executes the given task using concurrent marking worker threads.
4256   virtual void execute(ProcessTask& task);
4257   virtual void execute(EnqueueTask& task);
4258 };
4259 
4260 // Gang task for possibly parallel reference processing
4261 
4262 class G1STWRefProcTaskProxy: public AbstractGangTask {
4263   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4264   ProcessTask&     _proc_task;
4265   G1CollectedHeap* _g1h;
4266   G1ParScanThreadStateSet* _pss;
4267   RefToScanQueueSet* _task_queues;
4268   ParallelTaskTerminator* _terminator;
4269 
4270 public:
4271   G1STWRefProcTaskProxy(ProcessTask& proc_task,
4272                         G1CollectedHeap* g1h,
4273                         G1ParScanThreadStateSet* per_thread_states,
4274                         RefToScanQueueSet *task_queues,
4275                         ParallelTaskTerminator* terminator) :
4276     AbstractGangTask("Process reference objects in parallel"),
4277     _proc_task(proc_task),
4278     _g1h(g1h),
4279     _pss(per_thread_states),
4280     _task_queues(task_queues),
4281     _terminator(terminator)
4282   {}
4283 
4284   virtual void work(uint worker_id) {
4285     // The reference processing task executed by a single worker.
4286     ResourceMark rm;
4287     HandleMark   hm;
4288 
4289     G1STWIsAliveClosure is_alive(_g1h);
4290 
4291     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4292     pss->set_ref_processor(NULL);
4293 
4294     // Keep alive closure.
4295     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4296 
4297     // Complete GC closure
4298     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4299 
4300     // Call the reference processing task's work routine.
4301     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4302 
4303     // Note we cannot assert that the refs array is empty here as not all
4304     // of the processing tasks (specifically phase2 - pp2_work) execute
4305     // the complete_gc closure (which ordinarily would drain the queue) so
4306     // the queue may not be empty.
4307   }
4308 };
4309 
4310 // Driver routine for parallel reference processing.
4311 // Creates an instance of the ref processing gang
4312 // task and has the worker threads execute it.
4313 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4314   assert(_workers != NULL, "Need parallel worker threads.");
4315 
4316   ParallelTaskTerminator terminator(_active_workers, _queues);
4317   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4318 
4319   _workers->run_task(&proc_task_proxy);
4320 }
4321 
4322 // Gang task for parallel reference enqueueing.
4323 
4324 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4325   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4326   EnqueueTask& _enq_task;
4327 
4328 public:
4329   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4330     AbstractGangTask("Enqueue reference objects in parallel"),
4331     _enq_task(enq_task)
4332   { }
4333 
4334   virtual void work(uint worker_id) {
4335     _enq_task.work(worker_id);
4336   }
4337 };
4338 
4339 // Driver routine for parallel reference enqueueing.
4340 // Creates an instance of the ref enqueueing gang
4341 // task and has the worker threads execute it.
4342 
4343 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4344   assert(_workers != NULL, "Need parallel worker threads.");
4345 
4346   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4347 
4348   _workers->run_task(&enq_task_proxy);
4349 }
4350 
4351 // End of weak reference support closures
4352 
4353 // Abstract task used to preserve (i.e. copy) any referent objects
4354 // that are in the collection set and are pointed to by reference
4355 // objects discovered by the CM ref processor.
4356 
4357 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4358 protected:
4359   G1CollectedHeap*         _g1h;
4360   G1ParScanThreadStateSet* _pss;
4361   RefToScanQueueSet*       _queues;
4362   ParallelTaskTerminator   _terminator;
4363   uint                     _n_workers;
4364 
4365 public:
4366   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4367     AbstractGangTask("ParPreserveCMReferents"),
4368     _g1h(g1h),
4369     _pss(per_thread_states),
4370     _queues(task_queues),
4371     _terminator(workers, _queues),
4372     _n_workers(workers)
4373   {
4374     g1h->ref_processor_cm()->set_active_mt_degree(workers);
4375   }
4376 
4377   void work(uint worker_id) {
4378     G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4379 
4380     ResourceMark rm;
4381     HandleMark   hm;
4382 
4383     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4384     pss->set_ref_processor(NULL);
4385     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4386 
4387     // Is alive closure
4388     G1AlwaysAliveClosure always_alive(_g1h);
4389 
4390     // Copying keep alive closure. Applied to referent objects that need
4391     // to be copied.
4392     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4393 
4394     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4395 
4396     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4397     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4398 
4399     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4400     // So this must be true - but assert just in case someone decides to
4401     // change the worker ids.
4402     assert(worker_id < limit, "sanity");
4403     assert(!rp->discovery_is_atomic(), "check this code");
4404 
4405     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4406     for (uint idx = worker_id; idx < limit; idx += stride) {
4407       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4408 
4409       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4410       while (iter.has_next()) {
4411         // Since discovery is not atomic for the CM ref processor, we
4412         // can see some null referent objects.
4413         iter.load_ptrs(DEBUG_ONLY(true));
4414         oop ref = iter.obj();
4415 
4416         // This will filter nulls.
4417         if (iter.is_referent_alive()) {
4418           iter.make_referent_alive();
4419         }
4420         iter.move_to_next();
4421       }
4422     }
4423 
4424     // Drain the queue - which may cause stealing
4425     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4426     drain_queue.do_void();
4427     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4428     assert(pss->queue_is_empty(), "should be");
4429   }
4430 };
4431 
4432 void G1CollectedHeap::process_weak_jni_handles() {
4433   double ref_proc_start = os::elapsedTime();
4434 
4435   G1STWIsAliveClosure is_alive(this);
4436   G1KeepAliveClosure keep_alive(this);
4437   JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4438 
4439   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4440   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4441 }
4442 
4443 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4444   double preserve_cm_referents_start = os::elapsedTime();
4445   // Any reference objects, in the collection set, that were 'discovered'
4446   // by the CM ref processor should have already been copied (either by
4447   // applying the external root copy closure to the discovered lists, or
4448   // by following an RSet entry).
4449   //
4450   // But some of the referents, that are in the collection set, that these
4451   // reference objects point to may not have been copied: the STW ref
4452   // processor would have seen that the reference object had already
4453   // been 'discovered' and would have skipped discovering the reference,
4454   // but would not have treated the reference object as a regular oop.
4455   // As a result the copy closure would not have been applied to the
4456   // referent object.
4457   //
4458   // We need to explicitly copy these referent objects - the references
4459   // will be processed at the end of remarking.
4460   //
4461   // We also need to do this copying before we process the reference
4462   // objects discovered by the STW ref processor in case one of these
4463   // referents points to another object which is also referenced by an
4464   // object discovered by the STW ref processor.
4465 
4466   uint no_of_gc_workers = workers()->active_workers();
4467 
4468   G1ParPreserveCMReferentsTask keep_cm_referents(this,
4469                                                  per_thread_states,
4470                                                  no_of_gc_workers,
4471                                                  _task_queues);
4472   workers()->run_task(&keep_cm_referents);
4473 
4474   g1_policy()->phase_times()->record_preserve_cm_referents_time_ms((os::elapsedTime() - preserve_cm_referents_start) * 1000.0);
4475 }
4476 
4477 // Weak Reference processing during an evacuation pause (part 1).
4478 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4479   double ref_proc_start = os::elapsedTime();
4480 
4481   ReferenceProcessor* rp = _ref_processor_stw;
4482   assert(rp->discovery_enabled(), "should have been enabled");
4483 
4484   // Closure to test whether a referent is alive.
4485   G1STWIsAliveClosure is_alive(this);
4486 
4487   // Even when parallel reference processing is enabled, the processing
4488   // of JNI refs is serial and performed serially by the current thread
4489   // rather than by a worker. The following PSS will be used for processing
4490   // JNI refs.
4491 
4492   // Use only a single queue for this PSS.
4493   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4494   pss->set_ref_processor(NULL);
4495   assert(pss->queue_is_empty(), "pre-condition");
4496 
4497   // Keep alive closure.
4498   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4499 
4500   // Serial Complete GC closure
4501   G1STWDrainQueueClosure drain_queue(this, pss);
4502 
4503   // Setup the soft refs policy...
4504   rp->setup_policy(false);
4505 
4506   ReferenceProcessorStats stats;
4507   if (!rp->processing_is_mt()) {
4508     // Serial reference processing...
4509     stats = rp->process_discovered_references(&is_alive,
4510                                               &keep_alive,
4511                                               &drain_queue,
4512                                               NULL,
4513                                               _gc_timer_stw);
4514   } else {
4515     uint no_of_gc_workers = workers()->active_workers();
4516 
4517     // Parallel reference processing
4518     assert(no_of_gc_workers <= rp->max_num_q(),
4519            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4520            no_of_gc_workers,  rp->max_num_q());
4521 
4522     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4523     stats = rp->process_discovered_references(&is_alive,
4524                                               &keep_alive,
4525                                               &drain_queue,
4526                                               &par_task_executor,
4527                                               _gc_timer_stw);
4528   }
4529 
4530   _gc_tracer_stw->report_gc_reference_stats(stats);
4531 
4532   // We have completed copying any necessary live referent objects.
4533   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4534 
4535   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4536   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4537 }
4538 
4539 // Weak Reference processing during an evacuation pause (part 2).
4540 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4541   double ref_enq_start = os::elapsedTime();
4542 
4543   ReferenceProcessor* rp = _ref_processor_stw;
4544   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4545 
4546   // Now enqueue any remaining on the discovered lists on to
4547   // the pending list.
4548   if (!rp->processing_is_mt()) {
4549     // Serial reference processing...
4550     rp->enqueue_discovered_references();
4551   } else {
4552     // Parallel reference enqueueing
4553 
4554     uint n_workers = workers()->active_workers();
4555 
4556     assert(n_workers <= rp->max_num_q(),
4557            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4558            n_workers,  rp->max_num_q());
4559 
4560     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4561     rp->enqueue_discovered_references(&par_task_executor);
4562   }
4563 
4564   rp->verify_no_references_recorded();
4565   assert(!rp->discovery_enabled(), "should have been disabled");
4566 
4567   // FIXME
4568   // CM's reference processing also cleans up the string and symbol tables.
4569   // Should we do that here also? We could, but it is a serial operation
4570   // and could significantly increase the pause time.
4571 
4572   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4573   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4574 }
4575 
4576 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4577   double merge_pss_time_start = os::elapsedTime();
4578   per_thread_states->flush();
4579   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4580 }
4581 
4582 void G1CollectedHeap::pre_evacuate_collection_set() {
4583   _expand_heap_after_alloc_failure = true;
4584   _evacuation_failed = false;
4585 
4586   // Disable the hot card cache.
4587   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4588   hot_card_cache->reset_hot_cache_claimed_index();
4589   hot_card_cache->set_use_cache(false);
4590 
4591   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4592 }
4593 
4594 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4595   // Should G1EvacuationFailureALot be in effect for this GC?
4596   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4597 
4598   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4599   double start_par_time_sec = os::elapsedTime();
4600   double end_par_time_sec;
4601 
4602   {
4603     const uint n_workers = workers()->active_workers();
4604     G1RootProcessor root_processor(this, n_workers);
4605     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4606     // InitialMark needs claim bits to keep track of the marked-through CLDs.
4607     if (collector_state()->during_initial_mark_pause()) {
4608       ClassLoaderDataGraph::clear_claimed_marks();
4609     }
4610 
4611     print_termination_stats_hdr();
4612 
4613     workers()->run_task(&g1_par_task);
4614     end_par_time_sec = os::elapsedTime();
4615 
4616     // Closing the inner scope will execute the destructor
4617     // for the G1RootProcessor object. We record the current
4618     // elapsed time before closing the scope so that time
4619     // taken for the destructor is NOT included in the
4620     // reported parallel time.
4621   }
4622 
4623   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4624 
4625   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4626   phase_times->record_par_time(par_time_ms);
4627 
4628   double code_root_fixup_time_ms =
4629         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4630   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4631 }
4632 
4633 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4634   // Process any discovered reference objects - we have
4635   // to do this _before_ we retire the GC alloc regions
4636   // as we may have to copy some 'reachable' referent
4637   // objects (and their reachable sub-graphs) that were
4638   // not copied during the pause.
4639   if (g1_policy()->should_process_references()) {
4640     preserve_cm_referents(per_thread_states);
4641     process_discovered_references(per_thread_states);
4642   } else {
4643     ref_processor_stw()->verify_no_references_recorded();
4644     process_weak_jni_handles();
4645   }
4646 
4647   if (G1StringDedup::is_enabled()) {
4648     double fixup_start = os::elapsedTime();
4649 
4650     G1STWIsAliveClosure is_alive(this);
4651     G1KeepAliveClosure keep_alive(this);
4652     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4653 
4654     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4655     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4656   }
4657 
4658   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4659 
4660   if (evacuation_failed()) {
4661     restore_after_evac_failure();
4662 
4663     // Reset the G1EvacuationFailureALot counters and flags
4664     // Note: the values are reset only when an actual
4665     // evacuation failure occurs.
4666     NOT_PRODUCT(reset_evacuation_should_fail();)
4667   }
4668 
4669   // Enqueue any remaining references remaining on the STW
4670   // reference processor's discovered lists. We need to do
4671   // this after the card table is cleaned (and verified) as
4672   // the act of enqueueing entries on to the pending list
4673   // will log these updates (and dirty their associated
4674   // cards). We need these updates logged to update any
4675   // RSets.
4676   if (g1_policy()->should_process_references()) {
4677     enqueue_discovered_references(per_thread_states);
4678   } else {
4679     g1_policy()->phase_times()->record_ref_enq_time(0);
4680   }
4681 
4682   _allocator->release_gc_alloc_regions(evacuation_info);
4683 
4684   merge_per_thread_state_info(per_thread_states);
4685 
4686   // Reset and re-enable the hot card cache.
4687   // Note the counts for the cards in the regions in the
4688   // collection set are reset when the collection set is freed.
4689   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4690   hot_card_cache->reset_hot_cache();
4691   hot_card_cache->set_use_cache(true);
4692 
4693   purge_code_root_memory();
4694 
4695   redirty_logged_cards();
4696 #if defined(COMPILER2) || INCLUDE_JVMCI
4697   DerivedPointerTable::update_pointers();
4698 #endif
4699 }
4700 
4701 void G1CollectedHeap::record_obj_copy_mem_stats() {
4702   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4703 
4704   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4705                                                create_g1_evac_summary(&_old_evac_stats));
4706 }
4707 
4708 void G1CollectedHeap::free_region(HeapRegion* hr,
4709                                   FreeRegionList* free_list,
4710                                   bool par,
4711                                   bool locked) {
4712   assert(!hr->is_free(), "the region should not be free");
4713   assert(!hr->is_empty(), "the region should not be empty");
4714   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4715   assert(free_list != NULL, "pre-condition");
4716 
4717   if (G1VerifyBitmaps) {
4718     MemRegion mr(hr->bottom(), hr->end());
4719     concurrent_mark()->clearRangePrevBitmap(mr);
4720   }
4721 
4722   // Clear the card counts for this region.
4723   // Note: we only need to do this if the region is not young
4724   // (since we don't refine cards in young regions).
4725   if (!hr->is_young()) {
4726     _cg1r->hot_card_cache()->reset_card_counts(hr);
4727   }
4728   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
4729   free_list->add_ordered(hr);
4730 }
4731 
4732 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4733                                             FreeRegionList* free_list,
4734                                             bool par) {
4735   assert(hr->is_humongous(), "this is only for humongous regions");
4736   assert(free_list != NULL, "pre-condition");
4737   hr->clear_humongous();
4738   free_region(hr, free_list, par);
4739 }
4740 
4741 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4742                                            const uint humongous_regions_removed) {
4743   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4744     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4745     _old_set.bulk_remove(old_regions_removed);
4746     _humongous_set.bulk_remove(humongous_regions_removed);
4747   }
4748 
4749 }
4750 
4751 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4752   assert(list != NULL, "list can't be null");
4753   if (!list->is_empty()) {
4754     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4755     _hrm.insert_list_into_free_list(list);
4756   }
4757 }
4758 
4759 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4760   decrease_used(bytes);
4761 }
4762 
4763 class G1ParCleanupCTTask : public AbstractGangTask {
4764   G1SATBCardTableModRefBS* _ct_bs;
4765   G1CollectedHeap* _g1h;
4766   HeapRegion* volatile _su_head;
4767 public:
4768   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
4769                      G1CollectedHeap* g1h) :
4770     AbstractGangTask("G1 Par Cleanup CT Task"),
4771     _ct_bs(ct_bs), _g1h(g1h) { }
4772 
4773   void work(uint worker_id) {
4774     HeapRegion* r;
4775     while (r = _g1h->pop_dirty_cards_region()) {
4776       clear_cards(r);
4777     }
4778   }
4779 
4780   void clear_cards(HeapRegion* r) {
4781     // Cards of the survivors should have already been dirtied.
4782     if (!r->is_survivor()) {
4783       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4784     }
4785   }
4786 };
4787 
4788 class G1ParScrubRemSetTask: public AbstractGangTask {
4789 protected:
4790   G1RemSet* _g1rs;
4791   HeapRegionClaimer _hrclaimer;
4792 
4793 public:
4794   G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4795     AbstractGangTask("G1 ScrubRS"),
4796     _g1rs(g1_rs),
4797     _hrclaimer(num_workers) {
4798   }
4799 
4800   void work(uint worker_id) {
4801     _g1rs->scrub(worker_id, &_hrclaimer);
4802   }
4803 };
4804 
4805 void G1CollectedHeap::scrub_rem_set() {
4806   uint num_workers = workers()->active_workers();
4807   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4808   workers()->run_task(&g1_par_scrub_rs_task);
4809 }
4810 
4811 void G1CollectedHeap::cleanUpCardTable() {
4812   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
4813   double start = os::elapsedTime();
4814 
4815   {
4816     // Iterate over the dirty cards region list.
4817     G1ParCleanupCTTask cleanup_task(ct_bs, this);
4818 
4819     workers()->run_task(&cleanup_task);
4820 #ifndef PRODUCT
4821     _verifier->verify_card_table_cleanup();
4822 #endif
4823   }
4824 
4825   double elapsed = os::elapsedTime() - start;
4826   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
4827 }
4828 
4829 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4830   size_t pre_used = 0;
4831   FreeRegionList local_free_list("Local List for CSet Freeing");
4832 
4833   double young_time_ms     = 0.0;
4834   double non_young_time_ms = 0.0;
4835 
4836   // Since the collection set is a superset of the the young list,
4837   // all we need to do to clear the young list is clear its
4838   // head and length, and unlink any young regions in the code below
4839   _young_list->clear();
4840 
4841   G1CollectorPolicy* policy = g1_policy();
4842 
4843   double start_sec = os::elapsedTime();
4844   bool non_young = true;
4845 
4846   HeapRegion* cur = cs_head;
4847   int age_bound = -1;
4848   size_t rs_lengths = 0;
4849 
4850   while (cur != NULL) {
4851     assert(!is_on_master_free_list(cur), "sanity");
4852     if (non_young) {
4853       if (cur->is_young()) {
4854         double end_sec = os::elapsedTime();
4855         double elapsed_ms = (end_sec - start_sec) * 1000.0;
4856         non_young_time_ms += elapsed_ms;
4857 
4858         start_sec = os::elapsedTime();
4859         non_young = false;
4860       }
4861     } else {
4862       if (!cur->is_young()) {
4863         double end_sec = os::elapsedTime();
4864         double elapsed_ms = (end_sec - start_sec) * 1000.0;
4865         young_time_ms += elapsed_ms;
4866 
4867         start_sec = os::elapsedTime();
4868         non_young = true;
4869       }
4870     }
4871 
4872     rs_lengths += cur->rem_set()->occupied_locked();
4873 
4874     HeapRegion* next = cur->next_in_collection_set();
4875     assert(cur->in_collection_set(), "bad CS");
4876     cur->set_next_in_collection_set(NULL);
4877     clear_in_cset(cur);
4878 
4879     if (cur->is_young()) {
4880       int index = cur->young_index_in_cset();
4881       assert(index != -1, "invariant");
4882       assert((uint) index < collection_set()->young_region_length(), "invariant");
4883       size_t words_survived = surviving_young_words[index];
4884       cur->record_surv_words_in_group(words_survived);
4885 
4886       // At this point the we have 'popped' cur from the collection set
4887       // (linked via next_in_collection_set()) but it is still in the
4888       // young list (linked via next_young_region()). Clear the
4889       // _next_young_region field.
4890       cur->set_next_young_region(NULL);
4891     } else {
4892       int index = cur->young_index_in_cset();
4893       assert(index == -1, "invariant");
4894     }
4895 
4896     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4897             (!cur->is_young() && cur->young_index_in_cset() == -1),
4898             "invariant" );
4899 
4900     if (!cur->evacuation_failed()) {
4901       MemRegion used_mr = cur->used_region();
4902 
4903       // And the region is empty.
4904       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
4905       pre_used += cur->used();
4906       free_region(cur, &local_free_list, false /* par */, true /* locked */);
4907     } else {
4908       cur->uninstall_surv_rate_group();
4909       if (cur->is_young()) {
4910         cur->set_young_index_in_cset(-1);
4911       }
4912       cur->set_evacuation_failed(false);
4913       // When moving a young gen region to old gen, we "allocate" that whole region
4914       // there. This is in addition to any already evacuated objects. Notify the
4915       // policy about that.
4916       // Old gen regions do not cause an additional allocation: both the objects
4917       // still in the region and the ones already moved are accounted for elsewhere.
4918       if (cur->is_young()) {
4919         policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
4920       }
4921       // The region is now considered to be old.
4922       cur->set_old();
4923       // Do some allocation statistics accounting. Regions that failed evacuation
4924       // are always made old, so there is no need to update anything in the young
4925       // gen statistics, but we need to update old gen statistics.
4926       size_t used_words = cur->marked_bytes() / HeapWordSize;
4927       _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
4928       _old_set.add(cur);
4929       evacuation_info.increment_collectionset_used_after(cur->used());
4930     }
4931     cur = next;
4932   }
4933 
4934   evacuation_info.set_regions_freed(local_free_list.length());
4935   policy->record_max_rs_lengths(rs_lengths);
4936   policy->cset_regions_freed();
4937 
4938   double end_sec = os::elapsedTime();
4939   double elapsed_ms = (end_sec - start_sec) * 1000.0;
4940 
4941   if (non_young) {
4942     non_young_time_ms += elapsed_ms;
4943   } else {
4944     young_time_ms += elapsed_ms;
4945   }
4946 
4947   prepend_to_freelist(&local_free_list);
4948   decrement_summary_bytes(pre_used);
4949   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
4950   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
4951 }
4952 
4953 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4954  private:
4955   FreeRegionList* _free_region_list;
4956   HeapRegionSet* _proxy_set;
4957   uint _humongous_regions_removed;
4958   size_t _freed_bytes;
4959  public:
4960 
4961   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4962     _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4963   }
4964 
4965   virtual bool doHeapRegion(HeapRegion* r) {
4966     if (!r->is_starts_humongous()) {
4967       return false;
4968     }
4969 
4970     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4971 
4972     oop obj = (oop)r->bottom();
4973     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4974 
4975     // The following checks whether the humongous object is live are sufficient.
4976     // The main additional check (in addition to having a reference from the roots
4977     // or the young gen) is whether the humongous object has a remembered set entry.
4978     //
4979     // A humongous object cannot be live if there is no remembered set for it
4980     // because:
4981     // - there can be no references from within humongous starts regions referencing
4982     // the object because we never allocate other objects into them.
4983     // (I.e. there are no intra-region references that may be missed by the
4984     // remembered set)
4985     // - as soon there is a remembered set entry to the humongous starts region
4986     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4987     // until the end of a concurrent mark.
4988     //
4989     // It is not required to check whether the object has been found dead by marking
4990     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4991     // all objects allocated during that time are considered live.
4992     // SATB marking is even more conservative than the remembered set.
4993     // So if at this point in the collection there is no remembered set entry,
4994     // nobody has a reference to it.
4995     // At the start of collection we flush all refinement logs, and remembered sets
4996     // are completely up-to-date wrt to references to the humongous object.
4997     //
4998     // Other implementation considerations:
4999     // - never consider object arrays at this time because they would pose
5000     // considerable effort for cleaning up the the remembered sets. This is
5001     // required because stale remembered sets might reference locations that
5002     // are currently allocated into.
5003     uint region_idx = r->hrm_index();
5004     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5005         !r->rem_set()->is_empty()) {
5006       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",
5007                                region_idx,
5008                                (size_t)obj->size() * HeapWordSize,
5009                                p2i(r->bottom()),
5010                                r->rem_set()->occupied(),
5011                                r->rem_set()->strong_code_roots_list_length(),
5012                                next_bitmap->isMarked(r->bottom()),
5013                                g1h->is_humongous_reclaim_candidate(region_idx),
5014                                obj->is_typeArray()
5015                               );
5016       return false;
5017     }
5018 
5019     guarantee(obj->is_typeArray(),
5020               "Only eagerly reclaiming type arrays is supported, but the object "
5021               PTR_FORMAT " is not.", p2i(r->bottom()));
5022 
5023     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",
5024                              region_idx,
5025                              (size_t)obj->size() * HeapWordSize,
5026                              p2i(r->bottom()),
5027                              r->rem_set()->occupied(),
5028                              r->rem_set()->strong_code_roots_list_length(),
5029                              next_bitmap->isMarked(r->bottom()),
5030                              g1h->is_humongous_reclaim_candidate(region_idx),
5031                              obj->is_typeArray()
5032                             );
5033 
5034     // Need to clear mark bit of the humongous object if already set.
5035     if (next_bitmap->isMarked(r->bottom())) {
5036       next_bitmap->clear(r->bottom());
5037     }
5038     do {
5039       HeapRegion* next = g1h->next_region_in_humongous(r);
5040       _freed_bytes += r->used();
5041       r->set_containing_set(NULL);
5042       _humongous_regions_removed++;
5043       g1h->free_humongous_region(r, _free_region_list, false);
5044       r = next;
5045     } while (r != NULL);
5046 
5047     return false;
5048   }
5049 
5050   uint humongous_free_count() {
5051     return _humongous_regions_removed;
5052   }
5053 
5054   size_t bytes_freed() const {
5055     return _freed_bytes;
5056   }
5057 };
5058 
5059 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5060   assert_at_safepoint(true);
5061 
5062   if (!G1EagerReclaimHumongousObjects ||
5063       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5064     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5065     return;
5066   }
5067 
5068   double start_time = os::elapsedTime();
5069 
5070   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5071 
5072   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5073   heap_region_iterate(&cl);
5074 
5075   remove_from_old_sets(0, cl.humongous_free_count());
5076 
5077   G1HRPrinter* hrp = hr_printer();
5078   if (hrp->is_active()) {
5079     FreeRegionListIterator iter(&local_cleanup_list);
5080     while (iter.more_available()) {
5081       HeapRegion* hr = iter.get_next();
5082       hrp->cleanup(hr);
5083     }
5084   }
5085 
5086   prepend_to_freelist(&local_cleanup_list);
5087   decrement_summary_bytes(cl.bytes_freed());
5088 
5089   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5090                                                                     cl.humongous_free_count());
5091 }
5092 
5093 // This routine is similar to the above but does not record
5094 // any policy statistics or update free lists; we are abandoning
5095 // the current incremental collection set in preparation of a
5096 // full collection. After the full GC we will start to build up
5097 // the incremental collection set again.
5098 // This is only called when we're doing a full collection
5099 // and is immediately followed by the tearing down of the young list.
5100 
5101 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5102   HeapRegion* cur = cs_head;
5103 
5104   while (cur != NULL) {
5105     HeapRegion* next = cur->next_in_collection_set();
5106     assert(cur->in_collection_set(), "bad CS");
5107     cur->set_next_in_collection_set(NULL);
5108     clear_in_cset(cur);
5109     cur->set_young_index_in_cset(-1);
5110     cur = next;
5111   }
5112 }
5113 
5114 void G1CollectedHeap::set_free_regions_coming() {
5115   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5116 
5117   assert(!free_regions_coming(), "pre-condition");
5118   _free_regions_coming = true;
5119 }
5120 
5121 void G1CollectedHeap::reset_free_regions_coming() {
5122   assert(free_regions_coming(), "pre-condition");
5123 
5124   {
5125     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5126     _free_regions_coming = false;
5127     SecondaryFreeList_lock->notify_all();
5128   }
5129 
5130   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5131 }
5132 
5133 void G1CollectedHeap::wait_while_free_regions_coming() {
5134   // Most of the time we won't have to wait, so let's do a quick test
5135   // first before we take the lock.
5136   if (!free_regions_coming()) {
5137     return;
5138   }
5139 
5140   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5141 
5142   {
5143     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5144     while (free_regions_coming()) {
5145       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5146     }
5147   }
5148 
5149   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5150 }
5151 
5152 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5153   return _allocator->is_retained_old_region(hr);
5154 }
5155 
5156 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5157   _young_list->push_region(hr);
5158 }
5159 
5160 class NoYoungRegionsClosure: public HeapRegionClosure {
5161 private:
5162   bool _success;
5163 public:
5164   NoYoungRegionsClosure() : _success(true) { }
5165   bool doHeapRegion(HeapRegion* r) {
5166     if (r->is_young()) {
5167       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5168                             p2i(r->bottom()), p2i(r->end()));
5169       _success = false;
5170     }
5171     return false;
5172   }
5173   bool success() { return _success; }
5174 };
5175 
5176 bool G1CollectedHeap::check_young_list_empty(bool check_heap) {
5177   bool ret = _young_list->check_list_empty();
5178 
5179   if (check_heap) {
5180     NoYoungRegionsClosure closure;
5181     heap_region_iterate(&closure);
5182     ret = ret && closure.success();
5183   }
5184 
5185   return ret;
5186 }
5187 
5188 class TearDownRegionSetsClosure : public HeapRegionClosure {
5189 private:
5190   HeapRegionSet *_old_set;
5191 
5192 public:
5193   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5194 
5195   bool doHeapRegion(HeapRegion* r) {
5196     if (r->is_old()) {
5197       _old_set->remove(r);
5198     } else {
5199       // We ignore free regions, we'll empty the free list afterwards.
5200       // We ignore young regions, we'll empty the young list afterwards.
5201       // We ignore humongous regions, we're not tearing down the
5202       // humongous regions set.
5203       assert(r->is_free() || r->is_young() || r->is_humongous(),
5204              "it cannot be another type");
5205     }
5206     return false;
5207   }
5208 
5209   ~TearDownRegionSetsClosure() {
5210     assert(_old_set->is_empty(), "post-condition");
5211   }
5212 };
5213 
5214 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5215   assert_at_safepoint(true /* should_be_vm_thread */);
5216 
5217   if (!free_list_only) {
5218     TearDownRegionSetsClosure cl(&_old_set);
5219     heap_region_iterate(&cl);
5220 
5221     // Note that emptying the _young_list is postponed and instead done as
5222     // the first step when rebuilding the regions sets again. The reason for
5223     // this is that during a full GC string deduplication needs to know if
5224     // a collected region was young or old when the full GC was initiated.
5225   }
5226   _hrm.remove_all_free_regions();
5227 }
5228 
5229 void G1CollectedHeap::increase_used(size_t bytes) {
5230   _summary_bytes_used += bytes;
5231 }
5232 
5233 void G1CollectedHeap::decrease_used(size_t bytes) {
5234   assert(_summary_bytes_used >= bytes,
5235          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5236          _summary_bytes_used, bytes);
5237   _summary_bytes_used -= bytes;
5238 }
5239 
5240 void G1CollectedHeap::set_used(size_t bytes) {
5241   _summary_bytes_used = bytes;
5242 }
5243 
5244 class RebuildRegionSetsClosure : public HeapRegionClosure {
5245 private:
5246   bool            _free_list_only;
5247   HeapRegionSet*   _old_set;
5248   HeapRegionManager*   _hrm;
5249   size_t          _total_used;
5250 
5251 public:
5252   RebuildRegionSetsClosure(bool free_list_only,
5253                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5254     _free_list_only(free_list_only),
5255     _old_set(old_set), _hrm(hrm), _total_used(0) {
5256     assert(_hrm->num_free_regions() == 0, "pre-condition");
5257     if (!free_list_only) {
5258       assert(_old_set->is_empty(), "pre-condition");
5259     }
5260   }
5261 
5262   bool doHeapRegion(HeapRegion* r) {
5263     if (r->is_empty()) {
5264       // Add free regions to the free list
5265       r->set_free();
5266       r->set_allocation_context(AllocationContext::system());
5267       _hrm->insert_into_free_list(r);
5268     } else if (!_free_list_only) {
5269       assert(!r->is_young(), "we should not come across young regions");
5270 
5271       if (r->is_humongous()) {
5272         // We ignore humongous regions. We left the humongous set unchanged.
5273       } else {
5274         // Objects that were compacted would have ended up on regions
5275         // that were previously old or free.  Archive regions (which are
5276         // old) will not have been touched.
5277         assert(r->is_free() || r->is_old(), "invariant");
5278         // We now consider them old, so register as such. Leave
5279         // archive regions set that way, however, while still adding
5280         // them to the old set.
5281         if (!r->is_archive()) {
5282           r->set_old();
5283         }
5284         _old_set->add(r);
5285       }
5286       _total_used += r->used();
5287     }
5288 
5289     return false;
5290   }
5291 
5292   size_t total_used() {
5293     return _total_used;
5294   }
5295 };
5296 
5297 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5298   assert_at_safepoint(true /* should_be_vm_thread */);
5299 
5300   if (!free_list_only) {
5301     _young_list->empty_list();
5302   }
5303 
5304   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5305   heap_region_iterate(&cl);
5306 
5307   if (!free_list_only) {
5308     set_used(cl.total_used());
5309     if (_archive_allocator != NULL) {
5310       _archive_allocator->clear_used();
5311     }
5312   }
5313   assert(used_unlocked() == recalculate_used(),
5314          "inconsistent used_unlocked(), "
5315          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5316          used_unlocked(), recalculate_used());
5317 }
5318 
5319 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5320   _refine_cte_cl->set_concurrent(concurrent);
5321 }
5322 
5323 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5324   HeapRegion* hr = heap_region_containing(p);
5325   return hr->is_in(p);
5326 }
5327 
5328 // Methods for the mutator alloc region
5329 
5330 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5331                                                       bool force) {
5332   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5333   assert(!force || g1_policy()->can_expand_young_list(),
5334          "if force is true we should be able to expand the young list");
5335   bool young_list_full = g1_policy()->is_young_list_full();
5336   if (force || !young_list_full) {
5337     HeapRegion* new_alloc_region = new_region(word_size,
5338                                               false /* is_old */,
5339                                               false /* do_expand */);
5340     if (new_alloc_region != NULL) {
5341       set_region_short_lived_locked(new_alloc_region);
5342       _hr_printer.alloc(new_alloc_region, young_list_full);
5343       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5344       return new_alloc_region;
5345     }
5346   }
5347   return NULL;
5348 }
5349 
5350 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5351                                                   size_t allocated_bytes) {
5352   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5353   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5354 
5355   collection_set()->add_eden_region(alloc_region);
5356   increase_used(allocated_bytes);
5357   _hr_printer.retire(alloc_region);
5358   // We update the eden sizes here, when the region is retired,
5359   // instead of when it's allocated, since this is the point that its
5360   // used space has been recored in _summary_bytes_used.
5361   g1mm()->update_eden_size();
5362 }
5363 
5364 // Methods for the GC alloc regions
5365 
5366 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5367   if (dest.is_old()) {
5368     return true;
5369   } else {
5370     return young_list()->survivor_length() < g1_policy()->max_survivor_regions();
5371   }
5372 }
5373 
5374 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5375   assert(FreeList_lock->owned_by_self(), "pre-condition");
5376 
5377   if (!has_more_regions(dest)) {
5378     return NULL;
5379   }
5380 
5381   const bool is_survivor = dest.is_young();
5382 
5383   HeapRegion* new_alloc_region = new_region(word_size,
5384                                             !is_survivor,
5385                                             true /* do_expand */);
5386   if (new_alloc_region != NULL) {
5387     // We really only need to do this for old regions given that we
5388     // should never scan survivors. But it doesn't hurt to do it
5389     // for survivors too.
5390     new_alloc_region->record_timestamp();
5391     if (is_survivor) {
5392       new_alloc_region->set_survivor();
5393       young_list()->add_survivor_region(new_alloc_region);
5394       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5395     } else {
5396       new_alloc_region->set_old();
5397       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5398     }
5399     _hr_printer.alloc(new_alloc_region);
5400     bool during_im = collector_state()->during_initial_mark_pause();
5401     new_alloc_region->note_start_of_copying(during_im);
5402     return new_alloc_region;
5403   }
5404   return NULL;
5405 }
5406 
5407 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5408                                              size_t allocated_bytes,
5409                                              InCSetState dest) {
5410   bool during_im = collector_state()->during_initial_mark_pause();
5411   alloc_region->note_end_of_copying(during_im);
5412   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5413   if (dest.is_old()) {
5414     _old_set.add(alloc_region);
5415   }
5416   _hr_printer.retire(alloc_region);
5417 }
5418 
5419 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5420   bool expanded = false;
5421   uint index = _hrm.find_highest_free(&expanded);
5422 
5423   if (index != G1_NO_HRM_INDEX) {
5424     if (expanded) {
5425       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5426                                 HeapRegion::GrainWords * HeapWordSize);
5427     }
5428     _hrm.allocate_free_regions_starting_at(index, 1);
5429     return region_at(index);
5430   }
5431   return NULL;
5432 }
5433 
5434 // Optimized nmethod scanning
5435 
5436 class RegisterNMethodOopClosure: public OopClosure {
5437   G1CollectedHeap* _g1h;
5438   nmethod* _nm;
5439 
5440   template <class T> void do_oop_work(T* p) {
5441     T heap_oop = oopDesc::load_heap_oop(p);
5442     if (!oopDesc::is_null(heap_oop)) {
5443       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5444       HeapRegion* hr = _g1h->heap_region_containing(obj);
5445       assert(!hr->is_continues_humongous(),
5446              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5447              " starting at " HR_FORMAT,
5448              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5449 
5450       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5451       hr->add_strong_code_root_locked(_nm);
5452     }
5453   }
5454 
5455 public:
5456   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5457     _g1h(g1h), _nm(nm) {}
5458 
5459   void do_oop(oop* p)       { do_oop_work(p); }
5460   void do_oop(narrowOop* p) { do_oop_work(p); }
5461 };
5462 
5463 class UnregisterNMethodOopClosure: public OopClosure {
5464   G1CollectedHeap* _g1h;
5465   nmethod* _nm;
5466 
5467   template <class T> void do_oop_work(T* p) {
5468     T heap_oop = oopDesc::load_heap_oop(p);
5469     if (!oopDesc::is_null(heap_oop)) {
5470       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5471       HeapRegion* hr = _g1h->heap_region_containing(obj);
5472       assert(!hr->is_continues_humongous(),
5473              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5474              " starting at " HR_FORMAT,
5475              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5476 
5477       hr->remove_strong_code_root(_nm);
5478     }
5479   }
5480 
5481 public:
5482   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5483     _g1h(g1h), _nm(nm) {}
5484 
5485   void do_oop(oop* p)       { do_oop_work(p); }
5486   void do_oop(narrowOop* p) { do_oop_work(p); }
5487 };
5488 
5489 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5490   CollectedHeap::register_nmethod(nm);
5491 
5492   guarantee(nm != NULL, "sanity");
5493   RegisterNMethodOopClosure reg_cl(this, nm);
5494   nm->oops_do(&reg_cl);
5495 }
5496 
5497 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5498   CollectedHeap::unregister_nmethod(nm);
5499 
5500   guarantee(nm != NULL, "sanity");
5501   UnregisterNMethodOopClosure reg_cl(this, nm);
5502   nm->oops_do(&reg_cl, true);
5503 }
5504 
5505 void G1CollectedHeap::purge_code_root_memory() {
5506   double purge_start = os::elapsedTime();
5507   G1CodeRootSet::purge();
5508   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5509   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5510 }
5511 
5512 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5513   G1CollectedHeap* _g1h;
5514 
5515 public:
5516   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5517     _g1h(g1h) {}
5518 
5519   void do_code_blob(CodeBlob* cb) {
5520     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5521     if (nm == NULL) {
5522       return;
5523     }
5524 
5525     if (ScavengeRootsInCode) {
5526       _g1h->register_nmethod(nm);
5527     }
5528   }
5529 };
5530 
5531 void G1CollectedHeap::rebuild_strong_code_roots() {
5532   RebuildStrongCodeRootClosure blob_cl(this);
5533   CodeCache::blobs_do(&blob_cl);
5534 }