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 
1833   os::trace_page_sizes_for_requested_size(description,
1834                                           size,
1835                                           preferred_page_size,
1836                                           rs.alignment(),
1837                                           rs.base(),
1838                                           rs.size());
1839 
1840   return result;
1841 }
1842 
1843 jint G1CollectedHeap::initialize() {
1844   CollectedHeap::pre_initialize();
1845   os::enable_vtime();
1846 
1847   // Necessary to satisfy locking discipline assertions.
1848 
1849   MutexLocker x(Heap_lock);
1850 
1851   // While there are no constraints in the GC code that HeapWordSize
1852   // be any particular value, there are multiple other areas in the
1853   // system which believe this to be true (e.g. oop->object_size in some
1854   // cases incorrectly returns the size in wordSize units rather than
1855   // HeapWordSize).
1856   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1857 
1858   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1859   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1860   size_t heap_alignment = collector_policy()->heap_alignment();
1861 
1862   // Ensure that the sizes are properly aligned.
1863   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1864   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1865   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1866 
1867   _refine_cte_cl = new RefineCardTableEntryClosure();
1868 
1869   jint ecode = JNI_OK;
1870   _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1871   if (_cg1r == NULL) {
1872     return ecode;
1873   }
1874 
1875   // Reserve the maximum.
1876 
1877   // When compressed oops are enabled, the preferred heap base
1878   // is calculated by subtracting the requested size from the
1879   // 32Gb boundary and using the result as the base address for
1880   // heap reservation. If the requested size is not aligned to
1881   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1882   // into the ReservedHeapSpace constructor) then the actual
1883   // base of the reserved heap may end up differing from the
1884   // address that was requested (i.e. the preferred heap base).
1885   // If this happens then we could end up using a non-optimal
1886   // compressed oops mode.
1887 
1888   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1889                                                  heap_alignment);
1890 
1891   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1892 
1893   // Create the barrier set for the entire reserved region.
1894   G1SATBCardTableLoggingModRefBS* bs
1895     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1896   bs->initialize();
1897   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1898   set_barrier_set(bs);
1899 
1900   // Also create a G1 rem set.
1901   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1902 
1903   // Carve out the G1 part of the heap.
1904   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1905   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1906   G1RegionToSpaceMapper* heap_storage =
1907     G1RegionToSpaceMapper::create_mapper(g1_rs,
1908                                          g1_rs.size(),
1909                                          page_size,
1910                                          HeapRegion::GrainBytes,
1911                                          1,
1912                                          mtJavaHeap);
1913   os::trace_page_sizes("Heap",
1914                        collector_policy()->min_heap_byte_size(),
1915                        max_byte_size,
1916                        page_size,
1917                        heap_rs.base(),
1918                        heap_rs.size());
1919   heap_storage->set_mapping_changed_listener(&_listener);
1920 
1921   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1922   G1RegionToSpaceMapper* bot_storage =
1923     create_aux_memory_mapper("Block Offset Table",
1924                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1925                              G1BlockOffsetTable::heap_map_factor());
1926 
1927   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1928   G1RegionToSpaceMapper* cardtable_storage =
1929     create_aux_memory_mapper("Card Table",
1930                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1931                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1932 
1933   G1RegionToSpaceMapper* card_counts_storage =
1934     create_aux_memory_mapper("Card Counts Table",
1935                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1936                              G1CardCounts::heap_map_factor());
1937 
1938   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1939   G1RegionToSpaceMapper* prev_bitmap_storage =
1940     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1941   G1RegionToSpaceMapper* next_bitmap_storage =
1942     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1943 
1944   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1945   g1_barrier_set()->initialize(cardtable_storage);
1946    // Do later initialization work for concurrent refinement.
1947   _cg1r->init(card_counts_storage);
1948 
1949   // 6843694 - ensure that the maximum region index can fit
1950   // in the remembered set structures.
1951   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1952   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1953 
1954   g1_rem_set()->initialize(max_capacity(), max_regions());
1955 
1956   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1957   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1958   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1959             "too many cards per region");
1960 
1961   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1962 
1963   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1964 
1965   {
1966     HeapWord* start = _hrm.reserved().start();
1967     HeapWord* end = _hrm.reserved().end();
1968     size_t granularity = HeapRegion::GrainBytes;
1969 
1970     _in_cset_fast_test.initialize(start, end, granularity);
1971     _humongous_reclaim_candidates.initialize(start, end, granularity);
1972   }
1973 
1974   // Create the G1ConcurrentMark data structure and thread.
1975   // (Must do this late, so that "max_regions" is defined.)
1976   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1977   if (_cm == NULL || !_cm->completed_initialization()) {
1978     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1979     return JNI_ENOMEM;
1980   }
1981   _cmThread = _cm->cmThread();
1982 
1983   // Now expand into the initial heap size.
1984   if (!expand(init_byte_size)) {
1985     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1986     return JNI_ENOMEM;
1987   }
1988 
1989   // Perform any initialization actions delegated to the policy.
1990   g1_policy()->init();
1991 
1992   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1993                                                SATB_Q_FL_lock,
1994                                                G1SATBProcessCompletedThreshold,
1995                                                Shared_SATB_Q_lock);
1996 
1997   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1998                                                 DirtyCardQ_CBL_mon,
1999                                                 DirtyCardQ_FL_lock,
2000                                                 (int)concurrent_g1_refine()->yellow_zone(),
2001                                                 (int)concurrent_g1_refine()->red_zone(),
2002                                                 Shared_DirtyCardQ_lock,
2003                                                 NULL,  // fl_owner
2004                                                 true); // init_free_ids
2005 
2006   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2007                                     DirtyCardQ_CBL_mon,
2008                                     DirtyCardQ_FL_lock,
2009                                     -1, // never trigger processing
2010                                     -1, // no limit on length
2011                                     Shared_DirtyCardQ_lock,
2012                                     &JavaThread::dirty_card_queue_set());
2013 
2014   // Here we allocate the dummy HeapRegion that is required by the
2015   // G1AllocRegion class.
2016   HeapRegion* dummy_region = _hrm.get_dummy_region();
2017 
2018   // We'll re-use the same region whether the alloc region will
2019   // require BOT updates or not and, if it doesn't, then a non-young
2020   // region will complain that it cannot support allocations without
2021   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2022   dummy_region->set_eden();
2023   // Make sure it's full.
2024   dummy_region->set_top(dummy_region->end());
2025   G1AllocRegion::setup(this, dummy_region);
2026 
2027   _allocator->init_mutator_alloc_region();
2028 
2029   // Do create of the monitoring and management support so that
2030   // values in the heap have been properly initialized.
2031   _g1mm = new G1MonitoringSupport(this);
2032 
2033   G1StringDedup::initialize();
2034 
2035   _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2036   for (uint i = 0; i < ParallelGCThreads; i++) {
2037     new (&_preserved_objs[i]) OopAndMarkOopStack();
2038   }
2039 
2040   return JNI_OK;
2041 }
2042 
2043 void G1CollectedHeap::stop() {
2044   // Stop all concurrent threads. We do this to make sure these threads
2045   // do not continue to execute and access resources (e.g. logging)
2046   // that are destroyed during shutdown.
2047   _cg1r->stop();
2048   _cmThread->stop();
2049   if (G1StringDedup::is_enabled()) {
2050     G1StringDedup::stop();
2051   }
2052 }
2053 
2054 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2055   return HeapRegion::max_region_size();
2056 }
2057 
2058 void G1CollectedHeap::post_initialize() {
2059   CollectedHeap::post_initialize();
2060   ref_processing_init();
2061 }
2062 
2063 void G1CollectedHeap::ref_processing_init() {
2064   // Reference processing in G1 currently works as follows:
2065   //
2066   // * There are two reference processor instances. One is
2067   //   used to record and process discovered references
2068   //   during concurrent marking; the other is used to
2069   //   record and process references during STW pauses
2070   //   (both full and incremental).
2071   // * Both ref processors need to 'span' the entire heap as
2072   //   the regions in the collection set may be dotted around.
2073   //
2074   // * For the concurrent marking ref processor:
2075   //   * Reference discovery is enabled at initial marking.
2076   //   * Reference discovery is disabled and the discovered
2077   //     references processed etc during remarking.
2078   //   * Reference discovery is MT (see below).
2079   //   * Reference discovery requires a barrier (see below).
2080   //   * Reference processing may or may not be MT
2081   //     (depending on the value of ParallelRefProcEnabled
2082   //     and ParallelGCThreads).
2083   //   * A full GC disables reference discovery by the CM
2084   //     ref processor and abandons any entries on it's
2085   //     discovered lists.
2086   //
2087   // * For the STW processor:
2088   //   * Non MT discovery is enabled at the start of a full GC.
2089   //   * Processing and enqueueing during a full GC is non-MT.
2090   //   * During a full GC, references are processed after marking.
2091   //
2092   //   * Discovery (may or may not be MT) is enabled at the start
2093   //     of an incremental evacuation pause.
2094   //   * References are processed near the end of a STW evacuation pause.
2095   //   * For both types of GC:
2096   //     * Discovery is atomic - i.e. not concurrent.
2097   //     * Reference discovery will not need a barrier.
2098 
2099   MemRegion mr = reserved_region();
2100 
2101   // Concurrent Mark ref processor
2102   _ref_processor_cm =
2103     new ReferenceProcessor(mr,    // span
2104                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2105                                 // mt processing
2106                            ParallelGCThreads,
2107                                 // degree of mt processing
2108                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2109                                 // mt discovery
2110                            MAX2(ParallelGCThreads, ConcGCThreads),
2111                                 // degree of mt discovery
2112                            false,
2113                                 // Reference discovery is not atomic
2114                            &_is_alive_closure_cm);
2115                                 // is alive closure
2116                                 // (for efficiency/performance)
2117 
2118   // STW ref processor
2119   _ref_processor_stw =
2120     new ReferenceProcessor(mr,    // span
2121                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2122                                 // mt processing
2123                            ParallelGCThreads,
2124                                 // degree of mt processing
2125                            (ParallelGCThreads > 1),
2126                                 // mt discovery
2127                            ParallelGCThreads,
2128                                 // degree of mt discovery
2129                            true,
2130                                 // Reference discovery is atomic
2131                            &_is_alive_closure_stw);
2132                                 // is alive closure
2133                                 // (for efficiency/performance)
2134 }
2135 
2136 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2137   return g1_policy();
2138 }
2139 
2140 size_t G1CollectedHeap::capacity() const {
2141   return _hrm.length() * HeapRegion::GrainBytes;
2142 }
2143 
2144 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2145   hr->reset_gc_time_stamp();
2146 }
2147 
2148 #ifndef PRODUCT
2149 
2150 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2151 private:
2152   unsigned _gc_time_stamp;
2153   bool _failures;
2154 
2155 public:
2156   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2157     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2158 
2159   virtual bool doHeapRegion(HeapRegion* hr) {
2160     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2161     if (_gc_time_stamp != region_gc_time_stamp) {
2162       log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2163                             region_gc_time_stamp, _gc_time_stamp);
2164       _failures = true;
2165     }
2166     return false;
2167   }
2168 
2169   bool failures() { return _failures; }
2170 };
2171 
2172 void G1CollectedHeap::check_gc_time_stamps() {
2173   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2174   heap_region_iterate(&cl);
2175   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2176 }
2177 #endif // PRODUCT
2178 
2179 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2180   _cg1r->hot_card_cache()->drain(cl, worker_i);
2181 }
2182 
2183 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2184   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2185   size_t n_completed_buffers = 0;
2186   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2187     n_completed_buffers++;
2188   }
2189   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2190   dcqs.clear_n_completed_buffers();
2191   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2192 }
2193 
2194 // Computes the sum of the storage used by the various regions.
2195 size_t G1CollectedHeap::used() const {
2196   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2197   if (_archive_allocator != NULL) {
2198     result += _archive_allocator->used();
2199   }
2200   return result;
2201 }
2202 
2203 size_t G1CollectedHeap::used_unlocked() const {
2204   return _summary_bytes_used;
2205 }
2206 
2207 class SumUsedClosure: public HeapRegionClosure {
2208   size_t _used;
2209 public:
2210   SumUsedClosure() : _used(0) {}
2211   bool doHeapRegion(HeapRegion* r) {
2212     _used += r->used();
2213     return false;
2214   }
2215   size_t result() { return _used; }
2216 };
2217 
2218 size_t G1CollectedHeap::recalculate_used() const {
2219   double recalculate_used_start = os::elapsedTime();
2220 
2221   SumUsedClosure blk;
2222   heap_region_iterate(&blk);
2223 
2224   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2225   return blk.result();
2226 }
2227 
2228 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2229   switch (cause) {
2230     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2231     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2232     case GCCause::_update_allocation_context_stats_inc: return true;
2233     case GCCause::_wb_conc_mark:                        return true;
2234     default :                                           return false;
2235   }
2236 }
2237 
2238 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2239   switch (cause) {
2240     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2241     case GCCause::_g1_humongous_allocation: return true;
2242     default:                                return is_user_requested_concurrent_full_gc(cause);
2243   }
2244 }
2245 
2246 #ifndef PRODUCT
2247 void G1CollectedHeap::allocate_dummy_regions() {
2248   // Let's fill up most of the region
2249   size_t word_size = HeapRegion::GrainWords - 1024;
2250   // And as a result the region we'll allocate will be humongous.
2251   guarantee(is_humongous(word_size), "sanity");
2252 
2253   // _filler_array_max_size is set to humongous object threshold
2254   // but temporarily change it to use CollectedHeap::fill_with_object().
2255   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2256 
2257   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2258     // Let's use the existing mechanism for the allocation
2259     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2260                                                  AllocationContext::system());
2261     if (dummy_obj != NULL) {
2262       MemRegion mr(dummy_obj, word_size);
2263       CollectedHeap::fill_with_object(mr);
2264     } else {
2265       // If we can't allocate once, we probably cannot allocate
2266       // again. Let's get out of the loop.
2267       break;
2268     }
2269   }
2270 }
2271 #endif // !PRODUCT
2272 
2273 void G1CollectedHeap::increment_old_marking_cycles_started() {
2274   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2275          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2276          "Wrong marking cycle count (started: %d, completed: %d)",
2277          _old_marking_cycles_started, _old_marking_cycles_completed);
2278 
2279   _old_marking_cycles_started++;
2280 }
2281 
2282 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2283   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2284 
2285   // We assume that if concurrent == true, then the caller is a
2286   // concurrent thread that was joined the Suspendible Thread
2287   // Set. If there's ever a cheap way to check this, we should add an
2288   // assert here.
2289 
2290   // Given that this method is called at the end of a Full GC or of a
2291   // concurrent cycle, and those can be nested (i.e., a Full GC can
2292   // interrupt a concurrent cycle), the number of full collections
2293   // completed should be either one (in the case where there was no
2294   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2295   // behind the number of full collections started.
2296 
2297   // This is the case for the inner caller, i.e. a Full GC.
2298   assert(concurrent ||
2299          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2300          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2301          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2302          "is inconsistent with _old_marking_cycles_completed = %u",
2303          _old_marking_cycles_started, _old_marking_cycles_completed);
2304 
2305   // This is the case for the outer caller, i.e. the concurrent cycle.
2306   assert(!concurrent ||
2307          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2308          "for outer caller (concurrent cycle): "
2309          "_old_marking_cycles_started = %u "
2310          "is inconsistent with _old_marking_cycles_completed = %u",
2311          _old_marking_cycles_started, _old_marking_cycles_completed);
2312 
2313   _old_marking_cycles_completed += 1;
2314 
2315   // We need to clear the "in_progress" flag in the CM thread before
2316   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2317   // is set) so that if a waiter requests another System.gc() it doesn't
2318   // incorrectly see that a marking cycle is still in progress.
2319   if (concurrent) {
2320     _cmThread->set_idle();
2321   }
2322 
2323   // This notify_all() will ensure that a thread that called
2324   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2325   // and it's waiting for a full GC to finish will be woken up. It is
2326   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2327   FullGCCount_lock->notify_all();
2328 }
2329 
2330 void G1CollectedHeap::collect(GCCause::Cause cause) {
2331   assert_heap_not_locked();
2332 
2333   uint gc_count_before;
2334   uint old_marking_count_before;
2335   uint full_gc_count_before;
2336   bool retry_gc;
2337 
2338   do {
2339     retry_gc = false;
2340 
2341     {
2342       MutexLocker ml(Heap_lock);
2343 
2344       // Read the GC count while holding the Heap_lock
2345       gc_count_before = total_collections();
2346       full_gc_count_before = total_full_collections();
2347       old_marking_count_before = _old_marking_cycles_started;
2348     }
2349 
2350     if (should_do_concurrent_full_gc(cause)) {
2351       // Schedule an initial-mark evacuation pause that will start a
2352       // concurrent cycle. We're setting word_size to 0 which means that
2353       // we are not requesting a post-GC allocation.
2354       VM_G1IncCollectionPause op(gc_count_before,
2355                                  0,     /* word_size */
2356                                  true,  /* should_initiate_conc_mark */
2357                                  g1_policy()->max_pause_time_ms(),
2358                                  cause);
2359       op.set_allocation_context(AllocationContext::current());
2360 
2361       VMThread::execute(&op);
2362       if (!op.pause_succeeded()) {
2363         if (old_marking_count_before == _old_marking_cycles_started) {
2364           retry_gc = op.should_retry_gc();
2365         } else {
2366           // A Full GC happened while we were trying to schedule the
2367           // initial-mark GC. No point in starting a new cycle given
2368           // that the whole heap was collected anyway.
2369         }
2370 
2371         if (retry_gc) {
2372           if (GCLocker::is_active_and_needs_gc()) {
2373             GCLocker::stall_until_clear();
2374           }
2375         }
2376       }
2377     } else {
2378       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2379           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2380 
2381         // Schedule a standard evacuation pause. We're setting word_size
2382         // to 0 which means that we are not requesting a post-GC allocation.
2383         VM_G1IncCollectionPause op(gc_count_before,
2384                                    0,     /* word_size */
2385                                    false, /* should_initiate_conc_mark */
2386                                    g1_policy()->max_pause_time_ms(),
2387                                    cause);
2388         VMThread::execute(&op);
2389       } else {
2390         // Schedule a Full GC.
2391         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2392         VMThread::execute(&op);
2393       }
2394     }
2395   } while (retry_gc);
2396 }
2397 
2398 bool G1CollectedHeap::is_in(const void* p) const {
2399   if (_hrm.reserved().contains(p)) {
2400     // Given that we know that p is in the reserved space,
2401     // heap_region_containing() should successfully
2402     // return the containing region.
2403     HeapRegion* hr = heap_region_containing(p);
2404     return hr->is_in(p);
2405   } else {
2406     return false;
2407   }
2408 }
2409 
2410 #ifdef ASSERT
2411 bool G1CollectedHeap::is_in_exact(const void* p) const {
2412   bool contains = reserved_region().contains(p);
2413   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2414   if (contains && available) {
2415     return true;
2416   } else {
2417     return false;
2418   }
2419 }
2420 #endif
2421 
2422 bool G1CollectedHeap::obj_in_cs(oop obj) {
2423   HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2424   return r != NULL && r->in_collection_set();
2425 }
2426 
2427 // Iteration functions.
2428 
2429 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2430 
2431 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2432   ExtendedOopClosure* _cl;
2433 public:
2434   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2435   bool doHeapRegion(HeapRegion* r) {
2436     if (!r->is_continues_humongous()) {
2437       r->oop_iterate(_cl);
2438     }
2439     return false;
2440   }
2441 };
2442 
2443 // Iterates an ObjectClosure over all objects within a HeapRegion.
2444 
2445 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2446   ObjectClosure* _cl;
2447 public:
2448   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2449   bool doHeapRegion(HeapRegion* r) {
2450     if (!r->is_continues_humongous()) {
2451       r->object_iterate(_cl);
2452     }
2453     return false;
2454   }
2455 };
2456 
2457 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2458   IterateObjectClosureRegionClosure blk(cl);
2459   heap_region_iterate(&blk);
2460 }
2461 
2462 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2463   _hrm.iterate(cl);
2464 }
2465 
2466 void
2467 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2468                                          uint worker_id,
2469                                          HeapRegionClaimer *hrclaimer,
2470                                          bool concurrent) const {
2471   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2472 }
2473 
2474 // Clear the cached CSet starting regions and (more importantly)
2475 // the time stamps. Called when we reset the GC time stamp.
2476 void G1CollectedHeap::clear_cset_start_regions() {
2477   assert(_worker_cset_start_region != NULL, "sanity");
2478   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2479 
2480   for (uint i = 0; i < ParallelGCThreads; i++) {
2481     _worker_cset_start_region[i] = NULL;
2482     _worker_cset_start_region_time_stamp[i] = 0;
2483   }
2484 }
2485 
2486 // Given the id of a worker, obtain or calculate a suitable
2487 // starting region for iterating over the current collection set.
2488 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2489   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2490 
2491   HeapRegion* result = NULL;
2492   unsigned gc_time_stamp = get_gc_time_stamp();
2493 
2494   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2495     // Cached starting region for current worker was set
2496     // during the current pause - so it's valid.
2497     // Note: the cached starting heap region may be NULL
2498     // (when the collection set is empty).
2499     result = _worker_cset_start_region[worker_i];
2500     assert(result == NULL || result->in_collection_set(), "sanity");
2501     return result;
2502   }
2503 
2504   // The cached entry was not valid so let's calculate
2505   // a suitable starting heap region for this worker.
2506 
2507   // We want the parallel threads to start their collection
2508   // set iteration at different collection set regions to
2509   // avoid contention.
2510   // If we have:
2511   //          n collection set regions
2512   //          p threads
2513   // Then thread t will start at region floor ((t * n) / p)
2514 
2515   result = collection_set()->head();
2516   uint cs_size = collection_set()->region_length();
2517   uint active_workers = workers()->active_workers();
2518 
2519   uint end_ind   = (cs_size * worker_i) / active_workers;
2520   uint start_ind = 0;
2521 
2522   if (worker_i > 0 &&
2523       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2524     // Previous workers starting region is valid
2525     // so let's iterate from there
2526     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2527     OrderAccess::loadload();
2528     result = _worker_cset_start_region[worker_i - 1];
2529   }
2530 
2531   for (uint i = start_ind; i < end_ind; i++) {
2532     result = result->next_in_collection_set();
2533   }
2534 
2535   // Note: the calculated starting heap region may be NULL
2536   // (when the collection set is empty).
2537   assert(result == NULL || result->in_collection_set(), "sanity");
2538   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2539          "should be updated only once per pause");
2540   _worker_cset_start_region[worker_i] = result;
2541   OrderAccess::storestore();
2542   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2543   return result;
2544 }
2545 
2546 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2547   HeapRegion* r = collection_set()->head();
2548   while (r != NULL) {
2549     HeapRegion* next = r->next_in_collection_set();
2550     if (cl->doHeapRegion(r)) {
2551       cl->incomplete();
2552       return;
2553     }
2554     r = next;
2555   }
2556 }
2557 
2558 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2559                                                   HeapRegionClosure *cl) {
2560   if (r == NULL) {
2561     // The CSet is empty so there's nothing to do.
2562     return;
2563   }
2564 
2565   assert(r->in_collection_set(),
2566          "Start region must be a member of the collection set.");
2567   HeapRegion* cur = r;
2568   while (cur != NULL) {
2569     HeapRegion* next = cur->next_in_collection_set();
2570     if (cl->doHeapRegion(cur) && false) {
2571       cl->incomplete();
2572       return;
2573     }
2574     cur = next;
2575   }
2576   cur = collection_set()->head();
2577   while (cur != r) {
2578     HeapRegion* next = cur->next_in_collection_set();
2579     if (cl->doHeapRegion(cur) && false) {
2580       cl->incomplete();
2581       return;
2582     }
2583     cur = next;
2584   }
2585 }
2586 
2587 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2588   HeapRegion* result = _hrm.next_region_in_heap(from);
2589   while (result != NULL && result->is_pinned()) {
2590     result = _hrm.next_region_in_heap(result);
2591   }
2592   return result;
2593 }
2594 
2595 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2596   HeapRegion* hr = heap_region_containing(addr);
2597   return hr->block_start(addr);
2598 }
2599 
2600 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2601   HeapRegion* hr = heap_region_containing(addr);
2602   return hr->block_size(addr);
2603 }
2604 
2605 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2606   HeapRegion* hr = heap_region_containing(addr);
2607   return hr->block_is_obj(addr);
2608 }
2609 
2610 bool G1CollectedHeap::supports_tlab_allocation() const {
2611   return true;
2612 }
2613 
2614 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2615   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2616 }
2617 
2618 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2619   return young_list()->eden_used_bytes();
2620 }
2621 
2622 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2623 // must be equal to the humongous object limit.
2624 size_t G1CollectedHeap::max_tlab_size() const {
2625   return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2626 }
2627 
2628 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2629   AllocationContext_t context = AllocationContext::current();
2630   return _allocator->unsafe_max_tlab_alloc(context);
2631 }
2632 
2633 size_t G1CollectedHeap::max_capacity() const {
2634   return _hrm.reserved().byte_size();
2635 }
2636 
2637 jlong G1CollectedHeap::millis_since_last_gc() {
2638   // assert(false, "NYI");
2639   return 0;
2640 }
2641 
2642 void G1CollectedHeap::prepare_for_verify() {
2643   _verifier->prepare_for_verify();
2644 }
2645 
2646 void G1CollectedHeap::verify(VerifyOption vo) {
2647   _verifier->verify(vo);
2648 }
2649 
2650 class PrintRegionClosure: public HeapRegionClosure {
2651   outputStream* _st;
2652 public:
2653   PrintRegionClosure(outputStream* st) : _st(st) {}
2654   bool doHeapRegion(HeapRegion* r) {
2655     r->print_on(_st);
2656     return false;
2657   }
2658 };
2659 
2660 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2661                                        const HeapRegion* hr,
2662                                        const VerifyOption vo) const {
2663   switch (vo) {
2664   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2665   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2666   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
2667   default:                            ShouldNotReachHere();
2668   }
2669   return false; // keep some compilers happy
2670 }
2671 
2672 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2673                                        const VerifyOption vo) const {
2674   switch (vo) {
2675   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2676   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2677   case VerifyOption_G1UseMarkWord: {
2678     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2679     return !obj->is_gc_marked() && !hr->is_archive();
2680   }
2681   default:                            ShouldNotReachHere();
2682   }
2683   return false; // keep some compilers happy
2684 }
2685 
2686 void G1CollectedHeap::print_heap_regions() const {
2687   Log(gc, heap, region) log;
2688   if (log.is_trace()) {
2689     ResourceMark rm;
2690     print_regions_on(log.trace_stream());
2691   }
2692 }
2693 
2694 void G1CollectedHeap::print_on(outputStream* st) const {
2695   st->print(" %-20s", "garbage-first heap");
2696   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2697             capacity()/K, used_unlocked()/K);
2698   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2699             p2i(_hrm.reserved().start()),
2700             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2701             p2i(_hrm.reserved().end()));
2702   st->cr();
2703   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2704   uint young_regions = _young_list->length();
2705   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2706             (size_t) young_regions * HeapRegion::GrainBytes / K);
2707   uint survivor_regions = _young_list->survivor_length();
2708   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2709             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2710   st->cr();
2711   MetaspaceAux::print_on(st);
2712 }
2713 
2714 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2715   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2716                "HS=humongous(starts), HC=humongous(continues), "
2717                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2718                "AC=allocation context, "
2719                "TAMS=top-at-mark-start (previous, next)");
2720   PrintRegionClosure blk(st);
2721   heap_region_iterate(&blk);
2722 }
2723 
2724 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2725   print_on(st);
2726 
2727   // Print the per-region information.
2728   print_regions_on(st);
2729 }
2730 
2731 void G1CollectedHeap::print_on_error(outputStream* st) const {
2732   this->CollectedHeap::print_on_error(st);
2733 
2734   if (_cm != NULL) {
2735     st->cr();
2736     _cm->print_on_error(st);
2737   }
2738 }
2739 
2740 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2741   workers()->print_worker_threads_on(st);
2742   _cmThread->print_on(st);
2743   st->cr();
2744   _cm->print_worker_threads_on(st);
2745   _cg1r->print_worker_threads_on(st);
2746   if (G1StringDedup::is_enabled()) {
2747     G1StringDedup::print_worker_threads_on(st);
2748   }
2749 }
2750 
2751 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2752   workers()->threads_do(tc);
2753   tc->do_thread(_cmThread);
2754   _cg1r->threads_do(tc);
2755   if (G1StringDedup::is_enabled()) {
2756     G1StringDedup::threads_do(tc);
2757   }
2758 }
2759 
2760 void G1CollectedHeap::print_tracing_info() const {
2761   g1_rem_set()->print_summary_info();
2762   concurrent_mark()->print_summary_info();
2763   g1_policy()->print_yg_surv_rate_info();
2764 }
2765 
2766 #ifndef PRODUCT
2767 // Helpful for debugging RSet issues.
2768 
2769 class PrintRSetsClosure : public HeapRegionClosure {
2770 private:
2771   const char* _msg;
2772   size_t _occupied_sum;
2773 
2774 public:
2775   bool doHeapRegion(HeapRegion* r) {
2776     HeapRegionRemSet* hrrs = r->rem_set();
2777     size_t occupied = hrrs->occupied();
2778     _occupied_sum += occupied;
2779 
2780     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2781     if (occupied == 0) {
2782       tty->print_cr("  RSet is empty");
2783     } else {
2784       hrrs->print();
2785     }
2786     tty->print_cr("----------");
2787     return false;
2788   }
2789 
2790   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2791     tty->cr();
2792     tty->print_cr("========================================");
2793     tty->print_cr("%s", msg);
2794     tty->cr();
2795   }
2796 
2797   ~PrintRSetsClosure() {
2798     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2799     tty->print_cr("========================================");
2800     tty->cr();
2801   }
2802 };
2803 
2804 void G1CollectedHeap::print_cset_rsets() {
2805   PrintRSetsClosure cl("Printing CSet RSets");
2806   collection_set_iterate(&cl);
2807 }
2808 
2809 void G1CollectedHeap::print_all_rsets() {
2810   PrintRSetsClosure cl("Printing All RSets");;
2811   heap_region_iterate(&cl);
2812 }
2813 #endif // PRODUCT
2814 
2815 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2816   YoungList* young_list = heap()->young_list();
2817 
2818   size_t eden_used_bytes = young_list->eden_used_bytes();
2819   size_t survivor_used_bytes = young_list->survivor_used_bytes();
2820   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2821 
2822   size_t eden_capacity_bytes =
2823     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2824 
2825   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2826   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2827                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2828 }
2829 
2830 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2831   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2832                        stats->unused(), stats->used(), stats->region_end_waste(),
2833                        stats->regions_filled(), stats->direct_allocated(),
2834                        stats->failure_used(), stats->failure_waste());
2835 }
2836 
2837 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2838   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2839   gc_tracer->report_gc_heap_summary(when, heap_summary);
2840 
2841   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2842   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2843 }
2844 
2845 G1CollectedHeap* G1CollectedHeap::heap() {
2846   CollectedHeap* heap = Universe::heap();
2847   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2848   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2849   return (G1CollectedHeap*)heap;
2850 }
2851 
2852 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2853   // always_do_update_barrier = false;
2854   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2855   // Fill TLAB's and such
2856   accumulate_statistics_all_tlabs();
2857   ensure_parsability(true);
2858 
2859   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2860 }
2861 
2862 void G1CollectedHeap::gc_epilogue(bool full) {
2863   // we are at the end of the GC. Total collections has already been increased.
2864   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2865 
2866   // FIXME: what is this about?
2867   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2868   // is set.
2869 #if defined(COMPILER2) || INCLUDE_JVMCI
2870   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2871 #endif
2872   // always_do_update_barrier = true;
2873 
2874   resize_all_tlabs();
2875   allocation_context_stats().update(full);
2876 
2877   // We have just completed a GC. Update the soft reference
2878   // policy with the new heap occupancy
2879   Universe::update_heap_info_at_gc();
2880 }
2881 
2882 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2883                                                uint gc_count_before,
2884                                                bool* succeeded,
2885                                                GCCause::Cause gc_cause) {
2886   assert_heap_not_locked_and_not_at_safepoint();
2887   VM_G1IncCollectionPause op(gc_count_before,
2888                              word_size,
2889                              false, /* should_initiate_conc_mark */
2890                              g1_policy()->max_pause_time_ms(),
2891                              gc_cause);
2892 
2893   op.set_allocation_context(AllocationContext::current());
2894   VMThread::execute(&op);
2895 
2896   HeapWord* result = op.result();
2897   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2898   assert(result == NULL || ret_succeeded,
2899          "the result should be NULL if the VM did not succeed");
2900   *succeeded = ret_succeeded;
2901 
2902   assert_heap_not_locked();
2903   return result;
2904 }
2905 
2906 void
2907 G1CollectedHeap::doConcurrentMark() {
2908   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2909   if (!_cmThread->in_progress()) {
2910     _cmThread->set_started();
2911     CGC_lock->notify();
2912   }
2913 }
2914 
2915 size_t G1CollectedHeap::pending_card_num() {
2916   size_t extra_cards = 0;
2917   JavaThread *curr = Threads::first();
2918   while (curr != NULL) {
2919     DirtyCardQueue& dcq = curr->dirty_card_queue();
2920     extra_cards += dcq.size();
2921     curr = curr->next();
2922   }
2923   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2924   size_t buffer_size = dcqs.buffer_size();
2925   size_t buffer_num = dcqs.completed_buffers_num();
2926 
2927   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2928   // in bytes - not the number of 'entries'. We need to convert
2929   // into a number of cards.
2930   return (buffer_size * buffer_num + extra_cards) / oopSize;
2931 }
2932 
2933 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2934  private:
2935   size_t _total_humongous;
2936   size_t _candidate_humongous;
2937 
2938   DirtyCardQueue _dcq;
2939 
2940   // We don't nominate objects with many remembered set entries, on
2941   // the assumption that such objects are likely still live.
2942   bool is_remset_small(HeapRegion* region) const {
2943     HeapRegionRemSet* const rset = region->rem_set();
2944     return G1EagerReclaimHumongousObjectsWithStaleRefs
2945       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2946       : rset->is_empty();
2947   }
2948 
2949   bool is_typeArray_region(HeapRegion* region) const {
2950     return oop(region->bottom())->is_typeArray();
2951   }
2952 
2953   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2954     assert(region->is_starts_humongous(), "Must start a humongous object");
2955 
2956     // Candidate selection must satisfy the following constraints
2957     // while concurrent marking is in progress:
2958     //
2959     // * In order to maintain SATB invariants, an object must not be
2960     // reclaimed if it was allocated before the start of marking and
2961     // has not had its references scanned.  Such an object must have
2962     // its references (including type metadata) scanned to ensure no
2963     // live objects are missed by the marking process.  Objects
2964     // allocated after the start of concurrent marking don't need to
2965     // be scanned.
2966     //
2967     // * An object must not be reclaimed if it is on the concurrent
2968     // mark stack.  Objects allocated after the start of concurrent
2969     // marking are never pushed on the mark stack.
2970     //
2971     // Nominating only objects allocated after the start of concurrent
2972     // marking is sufficient to meet both constraints.  This may miss
2973     // some objects that satisfy the constraints, but the marking data
2974     // structures don't support efficiently performing the needed
2975     // additional tests or scrubbing of the mark stack.
2976     //
2977     // However, we presently only nominate is_typeArray() objects.
2978     // A humongous object containing references induces remembered
2979     // set entries on other regions.  In order to reclaim such an
2980     // object, those remembered sets would need to be cleaned up.
2981     //
2982     // We also treat is_typeArray() objects specially, allowing them
2983     // to be reclaimed even if allocated before the start of
2984     // concurrent mark.  For this we rely on mark stack insertion to
2985     // exclude is_typeArray() objects, preventing reclaiming an object
2986     // that is in the mark stack.  We also rely on the metadata for
2987     // such objects to be built-in and so ensured to be kept live.
2988     // Frequent allocation and drop of large binary blobs is an
2989     // important use case for eager reclaim, and this special handling
2990     // may reduce needed headroom.
2991 
2992     return is_typeArray_region(region) && is_remset_small(region);
2993   }
2994 
2995  public:
2996   RegisterHumongousWithInCSetFastTestClosure()
2997   : _total_humongous(0),
2998     _candidate_humongous(0),
2999     _dcq(&JavaThread::dirty_card_queue_set()) {
3000   }
3001 
3002   virtual bool doHeapRegion(HeapRegion* r) {
3003     if (!r->is_starts_humongous()) {
3004       return false;
3005     }
3006     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3007 
3008     bool is_candidate = humongous_region_is_candidate(g1h, r);
3009     uint rindex = r->hrm_index();
3010     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3011     if (is_candidate) {
3012       _candidate_humongous++;
3013       g1h->register_humongous_region_with_cset(rindex);
3014       // Is_candidate already filters out humongous object with large remembered sets.
3015       // If we have a humongous object with a few remembered sets, we simply flush these
3016       // remembered set entries into the DCQS. That will result in automatic
3017       // re-evaluation of their remembered set entries during the following evacuation
3018       // phase.
3019       if (!r->rem_set()->is_empty()) {
3020         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3021                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3022         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3023         HeapRegionRemSetIterator hrrs(r->rem_set());
3024         size_t card_index;
3025         while (hrrs.has_next(card_index)) {
3026           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3027           // The remembered set might contain references to already freed
3028           // regions. Filter out such entries to avoid failing card table
3029           // verification.
3030           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3031             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3032               *card_ptr = CardTableModRefBS::dirty_card_val();
3033               _dcq.enqueue(card_ptr);
3034             }
3035           }
3036         }
3037         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3038                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3039                hrrs.n_yielded(), r->rem_set()->occupied());
3040         r->rem_set()->clear_locked();
3041       }
3042       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3043     }
3044     _total_humongous++;
3045 
3046     return false;
3047   }
3048 
3049   size_t total_humongous() const { return _total_humongous; }
3050   size_t candidate_humongous() const { return _candidate_humongous; }
3051 
3052   void flush_rem_set_entries() { _dcq.flush(); }
3053 };
3054 
3055 void G1CollectedHeap::register_humongous_regions_with_cset() {
3056   if (!G1EagerReclaimHumongousObjects) {
3057     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3058     return;
3059   }
3060   double time = os::elapsed_counter();
3061 
3062   // Collect reclaim candidate information and register candidates with cset.
3063   RegisterHumongousWithInCSetFastTestClosure cl;
3064   heap_region_iterate(&cl);
3065 
3066   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3067   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3068                                                                   cl.total_humongous(),
3069                                                                   cl.candidate_humongous());
3070   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3071 
3072   // Finally flush all remembered set entries to re-check into the global DCQS.
3073   cl.flush_rem_set_entries();
3074 }
3075 
3076 class VerifyRegionRemSetClosure : public HeapRegionClosure {
3077   public:
3078     bool doHeapRegion(HeapRegion* hr) {
3079       if (!hr->is_archive() && !hr->is_continues_humongous()) {
3080         hr->verify_rem_set();
3081       }
3082       return false;
3083     }
3084 };
3085 
3086 #ifdef ASSERT
3087 class VerifyCSetClosure: public HeapRegionClosure {
3088 public:
3089   bool doHeapRegion(HeapRegion* hr) {
3090     // Here we check that the CSet region's RSet is ready for parallel
3091     // iteration. The fields that we'll verify are only manipulated
3092     // when the region is part of a CSet and is collected. Afterwards,
3093     // we reset these fields when we clear the region's RSet (when the
3094     // region is freed) so they are ready when the region is
3095     // re-allocated. The only exception to this is if there's an
3096     // evacuation failure and instead of freeing the region we leave
3097     // it in the heap. In that case, we reset these fields during
3098     // evacuation failure handling.
3099     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3100 
3101     // Here's a good place to add any other checks we'd like to
3102     // perform on CSet regions.
3103     return false;
3104   }
3105 };
3106 #endif // ASSERT
3107 
3108 uint G1CollectedHeap::num_task_queues() const {
3109   return _task_queues->size();
3110 }
3111 
3112 #if TASKQUEUE_STATS
3113 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3114   st->print_raw_cr("GC Task Stats");
3115   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3116   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3117 }
3118 
3119 void G1CollectedHeap::print_taskqueue_stats() const {
3120   if (!log_is_enabled(Trace, gc, task, stats)) {
3121     return;
3122   }
3123   Log(gc, task, stats) log;
3124   ResourceMark rm;
3125   outputStream* st = log.trace_stream();
3126 
3127   print_taskqueue_stats_hdr(st);
3128 
3129   TaskQueueStats totals;
3130   const uint n = num_task_queues();
3131   for (uint i = 0; i < n; ++i) {
3132     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3133     totals += task_queue(i)->stats;
3134   }
3135   st->print_raw("tot "); totals.print(st); st->cr();
3136 
3137   DEBUG_ONLY(totals.verify());
3138 }
3139 
3140 void G1CollectedHeap::reset_taskqueue_stats() {
3141   const uint n = num_task_queues();
3142   for (uint i = 0; i < n; ++i) {
3143     task_queue(i)->stats.reset();
3144   }
3145 }
3146 #endif // TASKQUEUE_STATS
3147 
3148 void G1CollectedHeap::wait_for_root_region_scanning() {
3149   double scan_wait_start = os::elapsedTime();
3150   // We have to wait until the CM threads finish scanning the
3151   // root regions as it's the only way to ensure that all the
3152   // objects on them have been correctly scanned before we start
3153   // moving them during the GC.
3154   bool waited = _cm->root_regions()->wait_until_scan_finished();
3155   double wait_time_ms = 0.0;
3156   if (waited) {
3157     double scan_wait_end = os::elapsedTime();
3158     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3159   }
3160   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3161 }
3162 
3163 bool
3164 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3165   assert_at_safepoint(true /* should_be_vm_thread */);
3166   guarantee(!is_gc_active(), "collection is not reentrant");
3167 
3168   if (GCLocker::check_active_before_gc()) {
3169     return false;
3170   }
3171 
3172   _gc_timer_stw->register_gc_start();
3173 
3174   GCIdMark gc_id_mark;
3175   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3176 
3177   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3178   ResourceMark rm;
3179 
3180   wait_for_root_region_scanning();
3181 
3182   print_heap_before_gc();
3183   print_heap_regions();
3184   trace_heap_before_gc(_gc_tracer_stw);
3185 
3186   _verifier->verify_region_sets_optional();
3187   _verifier->verify_dirty_young_regions();
3188 
3189   // We should not be doing initial mark unless the conc mark thread is running
3190   if (!_cmThread->should_terminate()) {
3191     // This call will decide whether this pause is an initial-mark
3192     // pause. If it is, during_initial_mark_pause() will return true
3193     // for the duration of this pause.
3194     g1_policy()->decide_on_conc_mark_initiation();
3195   }
3196 
3197   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3198   assert(!collector_state()->during_initial_mark_pause() ||
3199           collector_state()->gcs_are_young(), "sanity");
3200 
3201   // We also do not allow mixed GCs during marking.
3202   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3203 
3204   // Record whether this pause is an initial mark. When the current
3205   // thread has completed its logging output and it's safe to signal
3206   // the CM thread, the flag's value in the policy has been reset.
3207   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3208 
3209   // Inner scope for scope based logging, timers, and stats collection
3210   {
3211     EvacuationInfo evacuation_info;
3212 
3213     if (collector_state()->during_initial_mark_pause()) {
3214       // We are about to start a marking cycle, so we increment the
3215       // full collection counter.
3216       increment_old_marking_cycles_started();
3217       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3218     }
3219 
3220     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3221 
3222     GCTraceCPUTime tcpu;
3223 
3224     FormatBuffer<> gc_string("Pause ");
3225     if (collector_state()->during_initial_mark_pause()) {
3226       gc_string.append("Initial Mark");
3227     } else if (collector_state()->gcs_are_young()) {
3228       gc_string.append("Young");
3229     } else {
3230       gc_string.append("Mixed");
3231     }
3232     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3233 
3234     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3235                                                                   workers()->active_workers(),
3236                                                                   Threads::number_of_non_daemon_threads());
3237     workers()->set_active_workers(active_workers);
3238 
3239     g1_policy()->note_gc_start();
3240 
3241     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3242     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3243 
3244     // If the secondary_free_list is not empty, append it to the
3245     // free_list. No need to wait for the cleanup operation to finish;
3246     // the region allocation code will check the secondary_free_list
3247     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3248     // set, skip this step so that the region allocation code has to
3249     // get entries from the secondary_free_list.
3250     if (!G1StressConcRegionFreeing) {
3251       append_secondary_free_list_if_not_empty_with_lock();
3252     }
3253 
3254     G1HeapTransition heap_transition(this);
3255     size_t heap_used_bytes_before_gc = used();
3256 
3257     assert(check_young_list_well_formed(), "young list should be well formed");
3258 
3259     // Don't dynamically change the number of GC threads this early.  A value of
3260     // 0 is used to indicate serial work.  When parallel work is done,
3261     // it will be set.
3262 
3263     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3264       IsGCActiveMark x;
3265 
3266       gc_prologue(false);
3267       increment_total_collections(false /* full gc */);
3268       increment_gc_time_stamp();
3269 
3270       if (VerifyRememberedSets) {
3271         log_info(gc, verify)("[Verifying RemSets before GC]");
3272         VerifyRegionRemSetClosure v_cl;
3273         heap_region_iterate(&v_cl);
3274       }
3275 
3276       _verifier->verify_before_gc();
3277 
3278       _verifier->check_bitmaps("GC Start");
3279 
3280 #if defined(COMPILER2) || INCLUDE_JVMCI
3281       DerivedPointerTable::clear();
3282 #endif
3283 
3284       // Please see comment in g1CollectedHeap.hpp and
3285       // G1CollectedHeap::ref_processing_init() to see how
3286       // reference processing currently works in G1.
3287 
3288       // Enable discovery in the STW reference processor
3289       if (g1_policy()->should_process_references()) {
3290         ref_processor_stw()->enable_discovery();
3291       } else {
3292         ref_processor_stw()->disable_discovery();
3293       }
3294 
3295       {
3296         // We want to temporarily turn off discovery by the
3297         // CM ref processor, if necessary, and turn it back on
3298         // on again later if we do. Using a scoped
3299         // NoRefDiscovery object will do this.
3300         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3301 
3302         // Forget the current alloc region (we might even choose it to be part
3303         // of the collection set!).
3304         _allocator->release_mutator_alloc_region();
3305 
3306         // This timing is only used by the ergonomics to handle our pause target.
3307         // It is unclear why this should not include the full pause. We will
3308         // investigate this in CR 7178365.
3309         //
3310         // Preserving the old comment here if that helps the investigation:
3311         //
3312         // The elapsed time induced by the start time below deliberately elides
3313         // the possible verification above.
3314         double sample_start_time_sec = os::elapsedTime();
3315 
3316         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3317 
3318         if (collector_state()->during_initial_mark_pause()) {
3319           concurrent_mark()->checkpointRootsInitialPre();
3320         }
3321 
3322         g1_policy()->finalize_collection_set(target_pause_time_ms);
3323 
3324         evacuation_info.set_collectionset_regions(collection_set()->region_length());
3325 
3326         // Make sure the remembered sets are up to date. This needs to be
3327         // done before register_humongous_regions_with_cset(), because the
3328         // remembered sets are used there to choose eager reclaim candidates.
3329         // If the remembered sets are not up to date we might miss some
3330         // entries that need to be handled.
3331         g1_rem_set()->cleanupHRRS();
3332 
3333         register_humongous_regions_with_cset();
3334 
3335         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3336 
3337         _cm->note_start_of_gc();
3338         // We call this after finalize_cset() to
3339         // ensure that the CSet has been finalized.
3340         _cm->verify_no_cset_oops();
3341 
3342         if (_hr_printer.is_active()) {
3343           HeapRegion* hr = collection_set()->head();
3344           while (hr != NULL) {
3345             _hr_printer.cset(hr);
3346             hr = hr->next_in_collection_set();
3347           }
3348         }
3349 
3350 #ifdef ASSERT
3351         VerifyCSetClosure cl;
3352         collection_set_iterate(&cl);
3353 #endif // ASSERT
3354 
3355         // Initialize the GC alloc regions.
3356         _allocator->init_gc_alloc_regions(evacuation_info);
3357 
3358         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3359         pre_evacuate_collection_set();
3360 
3361         // Actually do the work...
3362         evacuate_collection_set(evacuation_info, &per_thread_states);
3363 
3364         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3365 
3366         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3367         free_collection_set(collection_set()->head(), evacuation_info, surviving_young_words);
3368 
3369         eagerly_reclaim_humongous_regions();
3370 
3371         collection_set()->clear_head();
3372 
3373         record_obj_copy_mem_stats();
3374         _survivor_evac_stats.adjust_desired_plab_sz();
3375         _old_evac_stats.adjust_desired_plab_sz();
3376 
3377         // Start a new incremental collection set for the next pause.
3378         collection_set()->start_incremental_building();
3379 
3380         clear_cset_fast_test();
3381 
3382         // Don't check the whole heap at this point as the
3383         // GC alloc regions from this pause have been tagged
3384         // as survivors and moved on to the survivor list.
3385         // Survivor regions will fail the !is_young() check.
3386         assert(check_young_list_empty(false /* check_heap */),
3387           "young list should be empty");
3388 
3389         _young_list->reset_auxilary_lists();
3390 
3391         if (evacuation_failed()) {
3392           set_used(recalculate_used());
3393           if (_archive_allocator != NULL) {
3394             _archive_allocator->clear_used();
3395           }
3396           for (uint i = 0; i < ParallelGCThreads; i++) {
3397             if (_evacuation_failed_info_array[i].has_failed()) {
3398               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3399             }
3400           }
3401         } else {
3402           // The "used" of the the collection set have already been subtracted
3403           // when they were freed.  Add in the bytes evacuated.
3404           increase_used(g1_policy()->bytes_copied_during_gc());
3405         }
3406 
3407         if (collector_state()->during_initial_mark_pause()) {
3408           // We have to do this before we notify the CM threads that
3409           // they can start working to make sure that all the
3410           // appropriate initialization is done on the CM object.
3411           concurrent_mark()->checkpointRootsInitialPost();
3412           collector_state()->set_mark_in_progress(true);
3413           // Note that we don't actually trigger the CM thread at
3414           // this point. We do that later when we're sure that
3415           // the current thread has completed its logging output.
3416         }
3417 
3418         allocate_dummy_regions();
3419 
3420         _allocator->init_mutator_alloc_region();
3421 
3422         {
3423           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3424           if (expand_bytes > 0) {
3425             size_t bytes_before = capacity();
3426             // No need for an ergo logging here,
3427             // expansion_amount() does this when it returns a value > 0.
3428             double expand_ms;
3429             if (!expand(expand_bytes, &expand_ms)) {
3430               // We failed to expand the heap. Cannot do anything about it.
3431             }
3432             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3433           }
3434         }
3435 
3436         // We redo the verification but now wrt to the new CSet which
3437         // has just got initialized after the previous CSet was freed.
3438         _cm->verify_no_cset_oops();
3439         _cm->note_end_of_gc();
3440 
3441         // This timing is only used by the ergonomics to handle our pause target.
3442         // It is unclear why this should not include the full pause. We will
3443         // investigate this in CR 7178365.
3444         double sample_end_time_sec = os::elapsedTime();
3445         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3446         size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3447         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3448 
3449         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3450         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3451 
3452         MemoryService::track_memory_usage();
3453 
3454         // In prepare_for_verify() below we'll need to scan the deferred
3455         // update buffers to bring the RSets up-to-date if
3456         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3457         // the update buffers we'll probably need to scan cards on the
3458         // regions we just allocated to (i.e., the GC alloc
3459         // regions). However, during the last GC we called
3460         // set_saved_mark() on all the GC alloc regions, so card
3461         // scanning might skip the [saved_mark_word()...top()] area of
3462         // those regions (i.e., the area we allocated objects into
3463         // during the last GC). But it shouldn't. Given that
3464         // saved_mark_word() is conditional on whether the GC time stamp
3465         // on the region is current or not, by incrementing the GC time
3466         // stamp here we invalidate all the GC time stamps on all the
3467         // regions and saved_mark_word() will simply return top() for
3468         // all the regions. This is a nicer way of ensuring this rather
3469         // than iterating over the regions and fixing them. In fact, the
3470         // GC time stamp increment here also ensures that
3471         // saved_mark_word() will return top() between pauses, i.e.,
3472         // during concurrent refinement. So we don't need the
3473         // is_gc_active() check to decided which top to use when
3474         // scanning cards (see CR 7039627).
3475         increment_gc_time_stamp();
3476 
3477         if (VerifyRememberedSets) {
3478           log_info(gc, verify)("[Verifying RemSets after GC]");
3479           VerifyRegionRemSetClosure v_cl;
3480           heap_region_iterate(&v_cl);
3481         }
3482 
3483         _verifier->verify_after_gc();
3484         _verifier->check_bitmaps("GC End");
3485 
3486         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3487         ref_processor_stw()->verify_no_references_recorded();
3488 
3489         // CM reference discovery will be re-enabled if necessary.
3490       }
3491 
3492 #ifdef TRACESPINNING
3493       ParallelTaskTerminator::print_termination_counts();
3494 #endif
3495 
3496       gc_epilogue(false);
3497     }
3498 
3499     // Print the remainder of the GC log output.
3500     if (evacuation_failed()) {
3501       log_info(gc)("To-space exhausted");
3502     }
3503 
3504     g1_policy()->print_phases();
3505     heap_transition.print();
3506 
3507     // It is not yet to safe to tell the concurrent mark to
3508     // start as we have some optional output below. We don't want the
3509     // output from the concurrent mark thread interfering with this
3510     // logging output either.
3511 
3512     _hrm.verify_optional();
3513     _verifier->verify_region_sets_optional();
3514 
3515     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3516     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3517 
3518     print_heap_after_gc();
3519     print_heap_regions();
3520     trace_heap_after_gc(_gc_tracer_stw);
3521 
3522     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3523     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3524     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3525     // before any GC notifications are raised.
3526     g1mm()->update_sizes();
3527 
3528     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3529     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3530     _gc_timer_stw->register_gc_end();
3531     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3532   }
3533   // It should now be safe to tell the concurrent mark thread to start
3534   // without its logging output interfering with the logging output
3535   // that came from the pause.
3536 
3537   if (should_start_conc_mark) {
3538     // CAUTION: after the doConcurrentMark() call below,
3539     // the concurrent marking thread(s) could be running
3540     // concurrently with us. Make sure that anything after
3541     // this point does not assume that we are the only GC thread
3542     // running. Note: of course, the actual marking work will
3543     // not start until the safepoint itself is released in
3544     // SuspendibleThreadSet::desynchronize().
3545     doConcurrentMark();
3546   }
3547 
3548   return true;
3549 }
3550 
3551 void G1CollectedHeap::restore_preserved_marks() {
3552   G1RestorePreservedMarksTask rpm_task(_preserved_objs);
3553   workers()->run_task(&rpm_task);
3554 }
3555 
3556 void G1CollectedHeap::remove_self_forwarding_pointers() {
3557   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3558   workers()->run_task(&rsfp_task);
3559 }
3560 
3561 void G1CollectedHeap::restore_after_evac_failure() {
3562   double remove_self_forwards_start = os::elapsedTime();
3563 
3564   remove_self_forwarding_pointers();
3565   restore_preserved_marks();
3566 
3567   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3568 }
3569 
3570 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3571   if (!_evacuation_failed) {
3572     _evacuation_failed = true;
3573   }
3574 
3575   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3576 
3577   // We want to call the "for_promotion_failure" version only in the
3578   // case of a promotion failure.
3579   if (m->must_be_preserved_for_promotion_failure(obj)) {
3580     OopAndMarkOop elem(obj, m);
3581     _preserved_objs[worker_id].push(elem);
3582   }
3583 }
3584 
3585 bool G1ParEvacuateFollowersClosure::offer_termination() {
3586   G1ParScanThreadState* const pss = par_scan_state();
3587   start_term_time();
3588   const bool res = terminator()->offer_termination();
3589   end_term_time();
3590   return res;
3591 }
3592 
3593 void G1ParEvacuateFollowersClosure::do_void() {
3594   G1ParScanThreadState* const pss = par_scan_state();
3595   pss->trim_queue();
3596   do {
3597     pss->steal_and_trim_queue(queues());
3598   } while (!offer_termination());
3599 }
3600 
3601 class G1ParTask : public AbstractGangTask {
3602 protected:
3603   G1CollectedHeap*         _g1h;
3604   G1ParScanThreadStateSet* _pss;
3605   RefToScanQueueSet*       _queues;
3606   G1RootProcessor*         _root_processor;
3607   ParallelTaskTerminator   _terminator;
3608   uint                     _n_workers;
3609 
3610 public:
3611   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3612     : AbstractGangTask("G1 collection"),
3613       _g1h(g1h),
3614       _pss(per_thread_states),
3615       _queues(task_queues),
3616       _root_processor(root_processor),
3617       _terminator(n_workers, _queues),
3618       _n_workers(n_workers)
3619   {}
3620 
3621   void work(uint worker_id) {
3622     if (worker_id >= _n_workers) return;  // no work needed this round
3623 
3624     double start_sec = os::elapsedTime();
3625     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3626 
3627     {
3628       ResourceMark rm;
3629       HandleMark   hm;
3630 
3631       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3632 
3633       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3634       pss->set_ref_processor(rp);
3635 
3636       double start_strong_roots_sec = os::elapsedTime();
3637 
3638       _root_processor->evacuate_roots(pss->closures(), worker_id);
3639 
3640       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3641 
3642       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3643       // treating the nmethods visited to act as roots for concurrent marking.
3644       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3645       // objects copied by the current evacuation.
3646       size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3647                                                                              pss->closures()->weak_codeblobs(),
3648                                                                              worker_id);
3649 
3650       _pss->add_cards_scanned(worker_id, cards_scanned);
3651 
3652       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3653 
3654       double term_sec = 0.0;
3655       size_t evac_term_attempts = 0;
3656       {
3657         double start = os::elapsedTime();
3658         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3659         evac.do_void();
3660 
3661         evac_term_attempts = evac.term_attempts();
3662         term_sec = evac.term_time();
3663         double elapsed_sec = os::elapsedTime() - start;
3664         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3665         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3666         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3667       }
3668 
3669       assert(pss->queue_is_empty(), "should be empty");
3670 
3671       if (log_is_enabled(Debug, gc, task, stats)) {
3672         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3673         size_t lab_waste;
3674         size_t lab_undo_waste;
3675         pss->waste(lab_waste, lab_undo_waste);
3676         _g1h->print_termination_stats(worker_id,
3677                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3678                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3679                                       term_sec * 1000.0,                          /* evac term time */
3680                                       evac_term_attempts,                         /* evac term attempts */
3681                                       lab_waste,                                  /* alloc buffer waste */
3682                                       lab_undo_waste                              /* undo waste */
3683                                       );
3684       }
3685 
3686       // Close the inner scope so that the ResourceMark and HandleMark
3687       // destructors are executed here and are included as part of the
3688       // "GC Worker Time".
3689     }
3690     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3691   }
3692 };
3693 
3694 void G1CollectedHeap::print_termination_stats_hdr() {
3695   log_debug(gc, task, stats)("GC Termination Stats");
3696   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3697   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3698   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3699 }
3700 
3701 void G1CollectedHeap::print_termination_stats(uint worker_id,
3702                                               double elapsed_ms,
3703                                               double strong_roots_ms,
3704                                               double term_ms,
3705                                               size_t term_attempts,
3706                                               size_t alloc_buffer_waste,
3707                                               size_t undo_waste) const {
3708   log_debug(gc, task, stats)
3709               ("%3d %9.2f %9.2f %6.2f "
3710                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3711                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3712                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3713                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3714                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3715                alloc_buffer_waste * HeapWordSize / K,
3716                undo_waste * HeapWordSize / K);
3717 }
3718 
3719 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3720 private:
3721   BoolObjectClosure* _is_alive;
3722   int _initial_string_table_size;
3723   int _initial_symbol_table_size;
3724 
3725   bool  _process_strings;
3726   int _strings_processed;
3727   int _strings_removed;
3728 
3729   bool  _process_symbols;
3730   int _symbols_processed;
3731   int _symbols_removed;
3732 
3733 public:
3734   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3735     AbstractGangTask("String/Symbol Unlinking"),
3736     _is_alive(is_alive),
3737     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3738     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3739 
3740     _initial_string_table_size = StringTable::the_table()->table_size();
3741     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3742     if (process_strings) {
3743       StringTable::clear_parallel_claimed_index();
3744     }
3745     if (process_symbols) {
3746       SymbolTable::clear_parallel_claimed_index();
3747     }
3748   }
3749 
3750   ~G1StringSymbolTableUnlinkTask() {
3751     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3752               "claim value %d after unlink less than initial string table size %d",
3753               StringTable::parallel_claimed_index(), _initial_string_table_size);
3754     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3755               "claim value %d after unlink less than initial symbol table size %d",
3756               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3757 
3758     log_info(gc, stringtable)(
3759         "Cleaned string and symbol table, "
3760         "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3761         "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3762         strings_processed(), strings_removed(),
3763         symbols_processed(), symbols_removed());
3764   }
3765 
3766   void work(uint worker_id) {
3767     int strings_processed = 0;
3768     int strings_removed = 0;
3769     int symbols_processed = 0;
3770     int symbols_removed = 0;
3771     if (_process_strings) {
3772       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3773       Atomic::add(strings_processed, &_strings_processed);
3774       Atomic::add(strings_removed, &_strings_removed);
3775     }
3776     if (_process_symbols) {
3777       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3778       Atomic::add(symbols_processed, &_symbols_processed);
3779       Atomic::add(symbols_removed, &_symbols_removed);
3780     }
3781   }
3782 
3783   size_t strings_processed() const { return (size_t)_strings_processed; }
3784   size_t strings_removed()   const { return (size_t)_strings_removed; }
3785 
3786   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3787   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3788 };
3789 
3790 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3791 private:
3792   static Monitor* _lock;
3793 
3794   BoolObjectClosure* const _is_alive;
3795   const bool               _unloading_occurred;
3796   const uint               _num_workers;
3797 
3798   // Variables used to claim nmethods.
3799   nmethod* _first_nmethod;
3800   volatile nmethod* _claimed_nmethod;
3801 
3802   // The list of nmethods that need to be processed by the second pass.
3803   volatile nmethod* _postponed_list;
3804   volatile uint     _num_entered_barrier;
3805 
3806  public:
3807   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3808       _is_alive(is_alive),
3809       _unloading_occurred(unloading_occurred),
3810       _num_workers(num_workers),
3811       _first_nmethod(NULL),
3812       _claimed_nmethod(NULL),
3813       _postponed_list(NULL),
3814       _num_entered_barrier(0)
3815   {
3816     nmethod::increase_unloading_clock();
3817     // Get first alive nmethod
3818     NMethodIterator iter = NMethodIterator();
3819     if(iter.next_alive()) {
3820       _first_nmethod = iter.method();
3821     }
3822     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
3823   }
3824 
3825   ~G1CodeCacheUnloadingTask() {
3826     CodeCache::verify_clean_inline_caches();
3827 
3828     CodeCache::set_needs_cache_clean(false);
3829     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3830 
3831     CodeCache::verify_icholder_relocations();
3832   }
3833 
3834  private:
3835   void add_to_postponed_list(nmethod* nm) {
3836       nmethod* old;
3837       do {
3838         old = (nmethod*)_postponed_list;
3839         nm->set_unloading_next(old);
3840       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3841   }
3842 
3843   void clean_nmethod(nmethod* nm) {
3844     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3845 
3846     if (postponed) {
3847       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3848       add_to_postponed_list(nm);
3849     }
3850 
3851     // Mark that this thread has been cleaned/unloaded.
3852     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3853     nm->set_unloading_clock(nmethod::global_unloading_clock());
3854   }
3855 
3856   void clean_nmethod_postponed(nmethod* nm) {
3857     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3858   }
3859 
3860   static const int MaxClaimNmethods = 16;
3861 
3862   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
3863     nmethod* first;
3864     NMethodIterator last;
3865 
3866     do {
3867       *num_claimed_nmethods = 0;
3868 
3869       first = (nmethod*)_claimed_nmethod;
3870       last = NMethodIterator(first);
3871 
3872       if (first != NULL) {
3873 
3874         for (int i = 0; i < MaxClaimNmethods; i++) {
3875           if (!last.next_alive()) {
3876             break;
3877           }
3878           claimed_nmethods[i] = last.method();
3879           (*num_claimed_nmethods)++;
3880         }
3881       }
3882 
3883     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3884   }
3885 
3886   nmethod* claim_postponed_nmethod() {
3887     nmethod* claim;
3888     nmethod* next;
3889 
3890     do {
3891       claim = (nmethod*)_postponed_list;
3892       if (claim == NULL) {
3893         return NULL;
3894       }
3895 
3896       next = claim->unloading_next();
3897 
3898     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3899 
3900     return claim;
3901   }
3902 
3903  public:
3904   // Mark that we're done with the first pass of nmethod cleaning.
3905   void barrier_mark(uint worker_id) {
3906     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3907     _num_entered_barrier++;
3908     if (_num_entered_barrier == _num_workers) {
3909       ml.notify_all();
3910     }
3911   }
3912 
3913   // See if we have to wait for the other workers to
3914   // finish their first-pass nmethod cleaning work.
3915   void barrier_wait(uint worker_id) {
3916     if (_num_entered_barrier < _num_workers) {
3917       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3918       while (_num_entered_barrier < _num_workers) {
3919           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3920       }
3921     }
3922   }
3923 
3924   // Cleaning and unloading of nmethods. Some work has to be postponed
3925   // to the second pass, when we know which nmethods survive.
3926   void work_first_pass(uint worker_id) {
3927     // The first nmethods is claimed by the first worker.
3928     if (worker_id == 0 && _first_nmethod != NULL) {
3929       clean_nmethod(_first_nmethod);
3930       _first_nmethod = NULL;
3931     }
3932 
3933     int num_claimed_nmethods;
3934     nmethod* claimed_nmethods[MaxClaimNmethods];
3935 
3936     while (true) {
3937       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3938 
3939       if (num_claimed_nmethods == 0) {
3940         break;
3941       }
3942 
3943       for (int i = 0; i < num_claimed_nmethods; i++) {
3944         clean_nmethod(claimed_nmethods[i]);
3945       }
3946     }
3947   }
3948 
3949   void work_second_pass(uint worker_id) {
3950     nmethod* nm;
3951     // Take care of postponed nmethods.
3952     while ((nm = claim_postponed_nmethod()) != NULL) {
3953       clean_nmethod_postponed(nm);
3954     }
3955   }
3956 };
3957 
3958 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3959 
3960 class G1KlassCleaningTask : public StackObj {
3961   BoolObjectClosure*                      _is_alive;
3962   volatile jint                           _clean_klass_tree_claimed;
3963   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3964 
3965  public:
3966   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3967       _is_alive(is_alive),
3968       _clean_klass_tree_claimed(0),
3969       _klass_iterator() {
3970   }
3971 
3972  private:
3973   bool claim_clean_klass_tree_task() {
3974     if (_clean_klass_tree_claimed) {
3975       return false;
3976     }
3977 
3978     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3979   }
3980 
3981   InstanceKlass* claim_next_klass() {
3982     Klass* klass;
3983     do {
3984       klass =_klass_iterator.next_klass();
3985     } while (klass != NULL && !klass->is_instance_klass());
3986 
3987     // this can be null so don't call InstanceKlass::cast
3988     return static_cast<InstanceKlass*>(klass);
3989   }
3990 
3991 public:
3992 
3993   void clean_klass(InstanceKlass* ik) {
3994     ik->clean_weak_instanceklass_links(_is_alive);
3995   }
3996 
3997   void work() {
3998     ResourceMark rm;
3999 
4000     // One worker will clean the subklass/sibling klass tree.
4001     if (claim_clean_klass_tree_task()) {
4002       Klass::clean_subklass_tree(_is_alive);
4003     }
4004 
4005     // All workers will help cleaning the classes,
4006     InstanceKlass* klass;
4007     while ((klass = claim_next_klass()) != NULL) {
4008       clean_klass(klass);
4009     }
4010   }
4011 };
4012 
4013 // To minimize the remark pause times, the tasks below are done in parallel.
4014 class G1ParallelCleaningTask : public AbstractGangTask {
4015 private:
4016   G1StringSymbolTableUnlinkTask _string_symbol_task;
4017   G1CodeCacheUnloadingTask      _code_cache_task;
4018   G1KlassCleaningTask           _klass_cleaning_task;
4019 
4020 public:
4021   // The constructor is run in the VMThread.
4022   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4023       AbstractGangTask("Parallel Cleaning"),
4024       _string_symbol_task(is_alive, process_strings, process_symbols),
4025       _code_cache_task(num_workers, is_alive, unloading_occurred),
4026       _klass_cleaning_task(is_alive) {
4027   }
4028 
4029   // The parallel work done by all worker threads.
4030   void work(uint worker_id) {
4031     // Do first pass of code cache cleaning.
4032     _code_cache_task.work_first_pass(worker_id);
4033 
4034     // Let the threads mark that the first pass is done.
4035     _code_cache_task.barrier_mark(worker_id);
4036 
4037     // Clean the Strings and Symbols.
4038     _string_symbol_task.work(worker_id);
4039 
4040     // Wait for all workers to finish the first code cache cleaning pass.
4041     _code_cache_task.barrier_wait(worker_id);
4042 
4043     // Do the second code cache cleaning work, which realize on
4044     // the liveness information gathered during the first pass.
4045     _code_cache_task.work_second_pass(worker_id);
4046 
4047     // Clean all klasses that were not unloaded.
4048     _klass_cleaning_task.work();
4049   }
4050 };
4051 
4052 
4053 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4054                                         bool process_strings,
4055                                         bool process_symbols,
4056                                         bool class_unloading_occurred) {
4057   uint n_workers = workers()->active_workers();
4058 
4059   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4060                                         n_workers, class_unloading_occurred);
4061   workers()->run_task(&g1_unlink_task);
4062 }
4063 
4064 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4065                                                      bool process_strings, bool process_symbols) {
4066   { // Timing scope
4067     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4068     workers()->run_task(&g1_unlink_task);
4069   }
4070 }
4071 
4072 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4073  private:
4074   DirtyCardQueueSet* _queue;
4075   G1CollectedHeap* _g1h;
4076  public:
4077   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4078     _queue(queue), _g1h(g1h) { }
4079 
4080   virtual void work(uint worker_id) {
4081     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4082     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4083 
4084     RedirtyLoggedCardTableEntryClosure cl(_g1h);
4085     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4086 
4087     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4088   }
4089 };
4090 
4091 void G1CollectedHeap::redirty_logged_cards() {
4092   double redirty_logged_cards_start = os::elapsedTime();
4093 
4094   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4095   dirty_card_queue_set().reset_for_par_iteration();
4096   workers()->run_task(&redirty_task);
4097 
4098   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4099   dcq.merge_bufferlists(&dirty_card_queue_set());
4100   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4101 
4102   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4103 }
4104 
4105 // Weak Reference Processing support
4106 
4107 // An always "is_alive" closure that is used to preserve referents.
4108 // If the object is non-null then it's alive.  Used in the preservation
4109 // of referent objects that are pointed to by reference objects
4110 // discovered by the CM ref processor.
4111 class G1AlwaysAliveClosure: public BoolObjectClosure {
4112   G1CollectedHeap* _g1;
4113 public:
4114   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4115   bool do_object_b(oop p) {
4116     if (p != NULL) {
4117       return true;
4118     }
4119     return false;
4120   }
4121 };
4122 
4123 bool G1STWIsAliveClosure::do_object_b(oop p) {
4124   // An object is reachable if it is outside the collection set,
4125   // or is inside and copied.
4126   return !_g1->is_in_cset(p) || p->is_forwarded();
4127 }
4128 
4129 // Non Copying Keep Alive closure
4130 class G1KeepAliveClosure: public OopClosure {
4131   G1CollectedHeap* _g1;
4132 public:
4133   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4134   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4135   void do_oop(oop* p) {
4136     oop obj = *p;
4137     assert(obj != NULL, "the caller should have filtered out NULL values");
4138 
4139     const InCSetState cset_state = _g1->in_cset_state(obj);
4140     if (!cset_state.is_in_cset_or_humongous()) {
4141       return;
4142     }
4143     if (cset_state.is_in_cset()) {
4144       assert( obj->is_forwarded(), "invariant" );
4145       *p = obj->forwardee();
4146     } else {
4147       assert(!obj->is_forwarded(), "invariant" );
4148       assert(cset_state.is_humongous(),
4149              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4150       _g1->set_humongous_is_live(obj);
4151     }
4152   }
4153 };
4154 
4155 // Copying Keep Alive closure - can be called from both
4156 // serial and parallel code as long as different worker
4157 // threads utilize different G1ParScanThreadState instances
4158 // and different queues.
4159 
4160 class G1CopyingKeepAliveClosure: public OopClosure {
4161   G1CollectedHeap*         _g1h;
4162   OopClosure*              _copy_non_heap_obj_cl;
4163   G1ParScanThreadState*    _par_scan_state;
4164 
4165 public:
4166   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4167                             OopClosure* non_heap_obj_cl,
4168                             G1ParScanThreadState* pss):
4169     _g1h(g1h),
4170     _copy_non_heap_obj_cl(non_heap_obj_cl),
4171     _par_scan_state(pss)
4172   {}
4173 
4174   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4175   virtual void do_oop(      oop* p) { do_oop_work(p); }
4176 
4177   template <class T> void do_oop_work(T* p) {
4178     oop obj = oopDesc::load_decode_heap_oop(p);
4179 
4180     if (_g1h->is_in_cset_or_humongous(obj)) {
4181       // If the referent object has been forwarded (either copied
4182       // to a new location or to itself in the event of an
4183       // evacuation failure) then we need to update the reference
4184       // field and, if both reference and referent are in the G1
4185       // heap, update the RSet for the referent.
4186       //
4187       // If the referent has not been forwarded then we have to keep
4188       // it alive by policy. Therefore we have copy the referent.
4189       //
4190       // If the reference field is in the G1 heap then we can push
4191       // on the PSS queue. When the queue is drained (after each
4192       // phase of reference processing) the object and it's followers
4193       // will be copied, the reference field set to point to the
4194       // new location, and the RSet updated. Otherwise we need to
4195       // use the the non-heap or metadata closures directly to copy
4196       // the referent object and update the pointer, while avoiding
4197       // updating the RSet.
4198 
4199       if (_g1h->is_in_g1_reserved(p)) {
4200         _par_scan_state->push_on_queue(p);
4201       } else {
4202         assert(!Metaspace::contains((const void*)p),
4203                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4204         _copy_non_heap_obj_cl->do_oop(p);
4205       }
4206     }
4207   }
4208 };
4209 
4210 // Serial drain queue closure. Called as the 'complete_gc'
4211 // closure for each discovered list in some of the
4212 // reference processing phases.
4213 
4214 class G1STWDrainQueueClosure: public VoidClosure {
4215 protected:
4216   G1CollectedHeap* _g1h;
4217   G1ParScanThreadState* _par_scan_state;
4218 
4219   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4220 
4221 public:
4222   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4223     _g1h(g1h),
4224     _par_scan_state(pss)
4225   { }
4226 
4227   void do_void() {
4228     G1ParScanThreadState* const pss = par_scan_state();
4229     pss->trim_queue();
4230   }
4231 };
4232 
4233 // Parallel Reference Processing closures
4234 
4235 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4236 // processing during G1 evacuation pauses.
4237 
4238 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4239 private:
4240   G1CollectedHeap*          _g1h;
4241   G1ParScanThreadStateSet*  _pss;
4242   RefToScanQueueSet*        _queues;
4243   WorkGang*                 _workers;
4244   uint                      _active_workers;
4245 
4246 public:
4247   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4248                            G1ParScanThreadStateSet* per_thread_states,
4249                            WorkGang* workers,
4250                            RefToScanQueueSet *task_queues,
4251                            uint n_workers) :
4252     _g1h(g1h),
4253     _pss(per_thread_states),
4254     _queues(task_queues),
4255     _workers(workers),
4256     _active_workers(n_workers)
4257   {
4258     g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4259   }
4260 
4261   // Executes the given task using concurrent marking worker threads.
4262   virtual void execute(ProcessTask& task);
4263   virtual void execute(EnqueueTask& task);
4264 };
4265 
4266 // Gang task for possibly parallel reference processing
4267 
4268 class G1STWRefProcTaskProxy: public AbstractGangTask {
4269   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4270   ProcessTask&     _proc_task;
4271   G1CollectedHeap* _g1h;
4272   G1ParScanThreadStateSet* _pss;
4273   RefToScanQueueSet* _task_queues;
4274   ParallelTaskTerminator* _terminator;
4275 
4276 public:
4277   G1STWRefProcTaskProxy(ProcessTask& proc_task,
4278                         G1CollectedHeap* g1h,
4279                         G1ParScanThreadStateSet* per_thread_states,
4280                         RefToScanQueueSet *task_queues,
4281                         ParallelTaskTerminator* terminator) :
4282     AbstractGangTask("Process reference objects in parallel"),
4283     _proc_task(proc_task),
4284     _g1h(g1h),
4285     _pss(per_thread_states),
4286     _task_queues(task_queues),
4287     _terminator(terminator)
4288   {}
4289 
4290   virtual void work(uint worker_id) {
4291     // The reference processing task executed by a single worker.
4292     ResourceMark rm;
4293     HandleMark   hm;
4294 
4295     G1STWIsAliveClosure is_alive(_g1h);
4296 
4297     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4298     pss->set_ref_processor(NULL);
4299 
4300     // Keep alive closure.
4301     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4302 
4303     // Complete GC closure
4304     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4305 
4306     // Call the reference processing task's work routine.
4307     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4308 
4309     // Note we cannot assert that the refs array is empty here as not all
4310     // of the processing tasks (specifically phase2 - pp2_work) execute
4311     // the complete_gc closure (which ordinarily would drain the queue) so
4312     // the queue may not be empty.
4313   }
4314 };
4315 
4316 // Driver routine for parallel reference processing.
4317 // Creates an instance of the ref processing gang
4318 // task and has the worker threads execute it.
4319 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4320   assert(_workers != NULL, "Need parallel worker threads.");
4321 
4322   ParallelTaskTerminator terminator(_active_workers, _queues);
4323   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4324 
4325   _workers->run_task(&proc_task_proxy);
4326 }
4327 
4328 // Gang task for parallel reference enqueueing.
4329 
4330 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4331   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4332   EnqueueTask& _enq_task;
4333 
4334 public:
4335   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4336     AbstractGangTask("Enqueue reference objects in parallel"),
4337     _enq_task(enq_task)
4338   { }
4339 
4340   virtual void work(uint worker_id) {
4341     _enq_task.work(worker_id);
4342   }
4343 };
4344 
4345 // Driver routine for parallel reference enqueueing.
4346 // Creates an instance of the ref enqueueing gang
4347 // task and has the worker threads execute it.
4348 
4349 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4350   assert(_workers != NULL, "Need parallel worker threads.");
4351 
4352   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4353 
4354   _workers->run_task(&enq_task_proxy);
4355 }
4356 
4357 // End of weak reference support closures
4358 
4359 // Abstract task used to preserve (i.e. copy) any referent objects
4360 // that are in the collection set and are pointed to by reference
4361 // objects discovered by the CM ref processor.
4362 
4363 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4364 protected:
4365   G1CollectedHeap*         _g1h;
4366   G1ParScanThreadStateSet* _pss;
4367   RefToScanQueueSet*       _queues;
4368   ParallelTaskTerminator   _terminator;
4369   uint                     _n_workers;
4370 
4371 public:
4372   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4373     AbstractGangTask("ParPreserveCMReferents"),
4374     _g1h(g1h),
4375     _pss(per_thread_states),
4376     _queues(task_queues),
4377     _terminator(workers, _queues),
4378     _n_workers(workers)
4379   {
4380     g1h->ref_processor_cm()->set_active_mt_degree(workers);
4381   }
4382 
4383   void work(uint worker_id) {
4384     G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4385 
4386     ResourceMark rm;
4387     HandleMark   hm;
4388 
4389     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4390     pss->set_ref_processor(NULL);
4391     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4392 
4393     // Is alive closure
4394     G1AlwaysAliveClosure always_alive(_g1h);
4395 
4396     // Copying keep alive closure. Applied to referent objects that need
4397     // to be copied.
4398     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4399 
4400     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4401 
4402     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4403     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4404 
4405     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4406     // So this must be true - but assert just in case someone decides to
4407     // change the worker ids.
4408     assert(worker_id < limit, "sanity");
4409     assert(!rp->discovery_is_atomic(), "check this code");
4410 
4411     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4412     for (uint idx = worker_id; idx < limit; idx += stride) {
4413       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4414 
4415       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4416       while (iter.has_next()) {
4417         // Since discovery is not atomic for the CM ref processor, we
4418         // can see some null referent objects.
4419         iter.load_ptrs(DEBUG_ONLY(true));
4420         oop ref = iter.obj();
4421 
4422         // This will filter nulls.
4423         if (iter.is_referent_alive()) {
4424           iter.make_referent_alive();
4425         }
4426         iter.move_to_next();
4427       }
4428     }
4429 
4430     // Drain the queue - which may cause stealing
4431     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4432     drain_queue.do_void();
4433     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4434     assert(pss->queue_is_empty(), "should be");
4435   }
4436 };
4437 
4438 void G1CollectedHeap::process_weak_jni_handles() {
4439   double ref_proc_start = os::elapsedTime();
4440 
4441   G1STWIsAliveClosure is_alive(this);
4442   G1KeepAliveClosure keep_alive(this);
4443   JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4444 
4445   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4446   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4447 }
4448 
4449 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4450   double preserve_cm_referents_start = os::elapsedTime();
4451   // Any reference objects, in the collection set, that were 'discovered'
4452   // by the CM ref processor should have already been copied (either by
4453   // applying the external root copy closure to the discovered lists, or
4454   // by following an RSet entry).
4455   //
4456   // But some of the referents, that are in the collection set, that these
4457   // reference objects point to may not have been copied: the STW ref
4458   // processor would have seen that the reference object had already
4459   // been 'discovered' and would have skipped discovering the reference,
4460   // but would not have treated the reference object as a regular oop.
4461   // As a result the copy closure would not have been applied to the
4462   // referent object.
4463   //
4464   // We need to explicitly copy these referent objects - the references
4465   // will be processed at the end of remarking.
4466   //
4467   // We also need to do this copying before we process the reference
4468   // objects discovered by the STW ref processor in case one of these
4469   // referents points to another object which is also referenced by an
4470   // object discovered by the STW ref processor.
4471 
4472   uint no_of_gc_workers = workers()->active_workers();
4473 
4474   G1ParPreserveCMReferentsTask keep_cm_referents(this,
4475                                                  per_thread_states,
4476                                                  no_of_gc_workers,
4477                                                  _task_queues);
4478   workers()->run_task(&keep_cm_referents);
4479 
4480   g1_policy()->phase_times()->record_preserve_cm_referents_time_ms((os::elapsedTime() - preserve_cm_referents_start) * 1000.0);
4481 }
4482 
4483 // Weak Reference processing during an evacuation pause (part 1).
4484 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4485   double ref_proc_start = os::elapsedTime();
4486 
4487   ReferenceProcessor* rp = _ref_processor_stw;
4488   assert(rp->discovery_enabled(), "should have been enabled");
4489 
4490   // Closure to test whether a referent is alive.
4491   G1STWIsAliveClosure is_alive(this);
4492 
4493   // Even when parallel reference processing is enabled, the processing
4494   // of JNI refs is serial and performed serially by the current thread
4495   // rather than by a worker. The following PSS will be used for processing
4496   // JNI refs.
4497 
4498   // Use only a single queue for this PSS.
4499   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4500   pss->set_ref_processor(NULL);
4501   assert(pss->queue_is_empty(), "pre-condition");
4502 
4503   // Keep alive closure.
4504   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4505 
4506   // Serial Complete GC closure
4507   G1STWDrainQueueClosure drain_queue(this, pss);
4508 
4509   // Setup the soft refs policy...
4510   rp->setup_policy(false);
4511 
4512   ReferenceProcessorStats stats;
4513   if (!rp->processing_is_mt()) {
4514     // Serial reference processing...
4515     stats = rp->process_discovered_references(&is_alive,
4516                                               &keep_alive,
4517                                               &drain_queue,
4518                                               NULL,
4519                                               _gc_timer_stw);
4520   } else {
4521     uint no_of_gc_workers = workers()->active_workers();
4522 
4523     // Parallel reference processing
4524     assert(no_of_gc_workers <= rp->max_num_q(),
4525            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4526            no_of_gc_workers,  rp->max_num_q());
4527 
4528     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4529     stats = rp->process_discovered_references(&is_alive,
4530                                               &keep_alive,
4531                                               &drain_queue,
4532                                               &par_task_executor,
4533                                               _gc_timer_stw);
4534   }
4535 
4536   _gc_tracer_stw->report_gc_reference_stats(stats);
4537 
4538   // We have completed copying any necessary live referent objects.
4539   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4540 
4541   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4542   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4543 }
4544 
4545 // Weak Reference processing during an evacuation pause (part 2).
4546 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4547   double ref_enq_start = os::elapsedTime();
4548 
4549   ReferenceProcessor* rp = _ref_processor_stw;
4550   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4551 
4552   // Now enqueue any remaining on the discovered lists on to
4553   // the pending list.
4554   if (!rp->processing_is_mt()) {
4555     // Serial reference processing...
4556     rp->enqueue_discovered_references();
4557   } else {
4558     // Parallel reference enqueueing
4559 
4560     uint n_workers = workers()->active_workers();
4561 
4562     assert(n_workers <= rp->max_num_q(),
4563            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4564            n_workers,  rp->max_num_q());
4565 
4566     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4567     rp->enqueue_discovered_references(&par_task_executor);
4568   }
4569 
4570   rp->verify_no_references_recorded();
4571   assert(!rp->discovery_enabled(), "should have been disabled");
4572 
4573   // FIXME
4574   // CM's reference processing also cleans up the string and symbol tables.
4575   // Should we do that here also? We could, but it is a serial operation
4576   // and could significantly increase the pause time.
4577 
4578   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4579   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4580 }
4581 
4582 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4583   double merge_pss_time_start = os::elapsedTime();
4584   per_thread_states->flush();
4585   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4586 }
4587 
4588 void G1CollectedHeap::pre_evacuate_collection_set() {
4589   _expand_heap_after_alloc_failure = true;
4590   _evacuation_failed = false;
4591 
4592   // Disable the hot card cache.
4593   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4594   hot_card_cache->reset_hot_cache_claimed_index();
4595   hot_card_cache->set_use_cache(false);
4596 
4597   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4598 }
4599 
4600 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4601   // Should G1EvacuationFailureALot be in effect for this GC?
4602   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4603 
4604   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4605   double start_par_time_sec = os::elapsedTime();
4606   double end_par_time_sec;
4607 
4608   {
4609     const uint n_workers = workers()->active_workers();
4610     G1RootProcessor root_processor(this, n_workers);
4611     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4612     // InitialMark needs claim bits to keep track of the marked-through CLDs.
4613     if (collector_state()->during_initial_mark_pause()) {
4614       ClassLoaderDataGraph::clear_claimed_marks();
4615     }
4616 
4617     print_termination_stats_hdr();
4618 
4619     workers()->run_task(&g1_par_task);
4620     end_par_time_sec = os::elapsedTime();
4621 
4622     // Closing the inner scope will execute the destructor
4623     // for the G1RootProcessor object. We record the current
4624     // elapsed time before closing the scope so that time
4625     // taken for the destructor is NOT included in the
4626     // reported parallel time.
4627   }
4628 
4629   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4630 
4631   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4632   phase_times->record_par_time(par_time_ms);
4633 
4634   double code_root_fixup_time_ms =
4635         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4636   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4637 }
4638 
4639 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4640   // Process any discovered reference objects - we have
4641   // to do this _before_ we retire the GC alloc regions
4642   // as we may have to copy some 'reachable' referent
4643   // objects (and their reachable sub-graphs) that were
4644   // not copied during the pause.
4645   if (g1_policy()->should_process_references()) {
4646     preserve_cm_referents(per_thread_states);
4647     process_discovered_references(per_thread_states);
4648   } else {
4649     ref_processor_stw()->verify_no_references_recorded();
4650     process_weak_jni_handles();
4651   }
4652 
4653   if (G1StringDedup::is_enabled()) {
4654     double fixup_start = os::elapsedTime();
4655 
4656     G1STWIsAliveClosure is_alive(this);
4657     G1KeepAliveClosure keep_alive(this);
4658     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4659 
4660     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4661     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4662   }
4663 
4664   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4665 
4666   if (evacuation_failed()) {
4667     restore_after_evac_failure();
4668 
4669     // Reset the G1EvacuationFailureALot counters and flags
4670     // Note: the values are reset only when an actual
4671     // evacuation failure occurs.
4672     NOT_PRODUCT(reset_evacuation_should_fail();)
4673   }
4674 
4675   // Enqueue any remaining references remaining on the STW
4676   // reference processor's discovered lists. We need to do
4677   // this after the card table is cleaned (and verified) as
4678   // the act of enqueueing entries on to the pending list
4679   // will log these updates (and dirty their associated
4680   // cards). We need these updates logged to update any
4681   // RSets.
4682   if (g1_policy()->should_process_references()) {
4683     enqueue_discovered_references(per_thread_states);
4684   } else {
4685     g1_policy()->phase_times()->record_ref_enq_time(0);
4686   }
4687 
4688   _allocator->release_gc_alloc_regions(evacuation_info);
4689 
4690   merge_per_thread_state_info(per_thread_states);
4691 
4692   // Reset and re-enable the hot card cache.
4693   // Note the counts for the cards in the regions in the
4694   // collection set are reset when the collection set is freed.
4695   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4696   hot_card_cache->reset_hot_cache();
4697   hot_card_cache->set_use_cache(true);
4698 
4699   purge_code_root_memory();
4700 
4701   redirty_logged_cards();
4702 #if defined(COMPILER2) || INCLUDE_JVMCI
4703   DerivedPointerTable::update_pointers();
4704 #endif
4705 }
4706 
4707 void G1CollectedHeap::record_obj_copy_mem_stats() {
4708   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4709 
4710   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4711                                                create_g1_evac_summary(&_old_evac_stats));
4712 }
4713 
4714 void G1CollectedHeap::free_region(HeapRegion* hr,
4715                                   FreeRegionList* free_list,
4716                                   bool par,
4717                                   bool locked) {
4718   assert(!hr->is_free(), "the region should not be free");
4719   assert(!hr->is_empty(), "the region should not be empty");
4720   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4721   assert(free_list != NULL, "pre-condition");
4722 
4723   if (G1VerifyBitmaps) {
4724     MemRegion mr(hr->bottom(), hr->end());
4725     concurrent_mark()->clearRangePrevBitmap(mr);
4726   }
4727 
4728   // Clear the card counts for this region.
4729   // Note: we only need to do this if the region is not young
4730   // (since we don't refine cards in young regions).
4731   if (!hr->is_young()) {
4732     _cg1r->hot_card_cache()->reset_card_counts(hr);
4733   }
4734   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
4735   free_list->add_ordered(hr);
4736 }
4737 
4738 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4739                                             FreeRegionList* free_list,
4740                                             bool par) {
4741   assert(hr->is_humongous(), "this is only for humongous regions");
4742   assert(free_list != NULL, "pre-condition");
4743   hr->clear_humongous();
4744   free_region(hr, free_list, par);
4745 }
4746 
4747 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4748                                            const uint humongous_regions_removed) {
4749   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4750     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4751     _old_set.bulk_remove(old_regions_removed);
4752     _humongous_set.bulk_remove(humongous_regions_removed);
4753   }
4754 
4755 }
4756 
4757 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4758   assert(list != NULL, "list can't be null");
4759   if (!list->is_empty()) {
4760     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4761     _hrm.insert_list_into_free_list(list);
4762   }
4763 }
4764 
4765 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4766   decrease_used(bytes);
4767 }
4768 
4769 class G1ParCleanupCTTask : public AbstractGangTask {
4770   G1SATBCardTableModRefBS* _ct_bs;
4771   G1CollectedHeap* _g1h;
4772   HeapRegion* volatile _su_head;
4773 public:
4774   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
4775                      G1CollectedHeap* g1h) :
4776     AbstractGangTask("G1 Par Cleanup CT Task"),
4777     _ct_bs(ct_bs), _g1h(g1h) { }
4778 
4779   void work(uint worker_id) {
4780     HeapRegion* r;
4781     while (r = _g1h->pop_dirty_cards_region()) {
4782       clear_cards(r);
4783     }
4784   }
4785 
4786   void clear_cards(HeapRegion* r) {
4787     // Cards of the survivors should have already been dirtied.
4788     if (!r->is_survivor()) {
4789       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4790     }
4791   }
4792 };
4793 
4794 class G1ParScrubRemSetTask: public AbstractGangTask {
4795 protected:
4796   G1RemSet* _g1rs;
4797   HeapRegionClaimer _hrclaimer;
4798 
4799 public:
4800   G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4801     AbstractGangTask("G1 ScrubRS"),
4802     _g1rs(g1_rs),
4803     _hrclaimer(num_workers) {
4804   }
4805 
4806   void work(uint worker_id) {
4807     _g1rs->scrub(worker_id, &_hrclaimer);
4808   }
4809 };
4810 
4811 void G1CollectedHeap::scrub_rem_set() {
4812   uint num_workers = workers()->active_workers();
4813   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4814   workers()->run_task(&g1_par_scrub_rs_task);
4815 }
4816 
4817 void G1CollectedHeap::cleanUpCardTable() {
4818   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
4819   double start = os::elapsedTime();
4820 
4821   {
4822     // Iterate over the dirty cards region list.
4823     G1ParCleanupCTTask cleanup_task(ct_bs, this);
4824 
4825     workers()->run_task(&cleanup_task);
4826 #ifndef PRODUCT
4827     _verifier->verify_card_table_cleanup();
4828 #endif
4829   }
4830 
4831   double elapsed = os::elapsedTime() - start;
4832   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
4833 }
4834 
4835 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4836   size_t pre_used = 0;
4837   FreeRegionList local_free_list("Local List for CSet Freeing");
4838 
4839   double young_time_ms     = 0.0;
4840   double non_young_time_ms = 0.0;
4841 
4842   // Since the collection set is a superset of the the young list,
4843   // all we need to do to clear the young list is clear its
4844   // head and length, and unlink any young regions in the code below
4845   _young_list->clear();
4846 
4847   G1CollectorPolicy* policy = g1_policy();
4848 
4849   double start_sec = os::elapsedTime();
4850   bool non_young = true;
4851 
4852   HeapRegion* cur = cs_head;
4853   int age_bound = -1;
4854   size_t rs_lengths = 0;
4855 
4856   while (cur != NULL) {
4857     assert(!is_on_master_free_list(cur), "sanity");
4858     if (non_young) {
4859       if (cur->is_young()) {
4860         double end_sec = os::elapsedTime();
4861         double elapsed_ms = (end_sec - start_sec) * 1000.0;
4862         non_young_time_ms += elapsed_ms;
4863 
4864         start_sec = os::elapsedTime();
4865         non_young = false;
4866       }
4867     } else {
4868       if (!cur->is_young()) {
4869         double end_sec = os::elapsedTime();
4870         double elapsed_ms = (end_sec - start_sec) * 1000.0;
4871         young_time_ms += elapsed_ms;
4872 
4873         start_sec = os::elapsedTime();
4874         non_young = true;
4875       }
4876     }
4877 
4878     rs_lengths += cur->rem_set()->occupied_locked();
4879 
4880     HeapRegion* next = cur->next_in_collection_set();
4881     assert(cur->in_collection_set(), "bad CS");
4882     cur->set_next_in_collection_set(NULL);
4883     clear_in_cset(cur);
4884 
4885     if (cur->is_young()) {
4886       int index = cur->young_index_in_cset();
4887       assert(index != -1, "invariant");
4888       assert((uint) index < collection_set()->young_region_length(), "invariant");
4889       size_t words_survived = surviving_young_words[index];
4890       cur->record_surv_words_in_group(words_survived);
4891 
4892       // At this point the we have 'popped' cur from the collection set
4893       // (linked via next_in_collection_set()) but it is still in the
4894       // young list (linked via next_young_region()). Clear the
4895       // _next_young_region field.
4896       cur->set_next_young_region(NULL);
4897     } else {
4898       int index = cur->young_index_in_cset();
4899       assert(index == -1, "invariant");
4900     }
4901 
4902     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4903             (!cur->is_young() && cur->young_index_in_cset() == -1),
4904             "invariant" );
4905 
4906     if (!cur->evacuation_failed()) {
4907       MemRegion used_mr = cur->used_region();
4908 
4909       // And the region is empty.
4910       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
4911       pre_used += cur->used();
4912       free_region(cur, &local_free_list, false /* par */, true /* locked */);
4913     } else {
4914       cur->uninstall_surv_rate_group();
4915       if (cur->is_young()) {
4916         cur->set_young_index_in_cset(-1);
4917       }
4918       cur->set_evacuation_failed(false);
4919       // When moving a young gen region to old gen, we "allocate" that whole region
4920       // there. This is in addition to any already evacuated objects. Notify the
4921       // policy about that.
4922       // Old gen regions do not cause an additional allocation: both the objects
4923       // still in the region and the ones already moved are accounted for elsewhere.
4924       if (cur->is_young()) {
4925         policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
4926       }
4927       // The region is now considered to be old.
4928       cur->set_old();
4929       // Do some allocation statistics accounting. Regions that failed evacuation
4930       // are always made old, so there is no need to update anything in the young
4931       // gen statistics, but we need to update old gen statistics.
4932       size_t used_words = cur->marked_bytes() / HeapWordSize;
4933       _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
4934       _old_set.add(cur);
4935       evacuation_info.increment_collectionset_used_after(cur->used());
4936     }
4937     cur = next;
4938   }
4939 
4940   evacuation_info.set_regions_freed(local_free_list.length());
4941   policy->record_max_rs_lengths(rs_lengths);
4942   policy->cset_regions_freed();
4943 
4944   double end_sec = os::elapsedTime();
4945   double elapsed_ms = (end_sec - start_sec) * 1000.0;
4946 
4947   if (non_young) {
4948     non_young_time_ms += elapsed_ms;
4949   } else {
4950     young_time_ms += elapsed_ms;
4951   }
4952 
4953   prepend_to_freelist(&local_free_list);
4954   decrement_summary_bytes(pre_used);
4955   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
4956   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
4957 }
4958 
4959 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4960  private:
4961   FreeRegionList* _free_region_list;
4962   HeapRegionSet* _proxy_set;
4963   uint _humongous_regions_removed;
4964   size_t _freed_bytes;
4965  public:
4966 
4967   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4968     _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4969   }
4970 
4971   virtual bool doHeapRegion(HeapRegion* r) {
4972     if (!r->is_starts_humongous()) {
4973       return false;
4974     }
4975 
4976     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4977 
4978     oop obj = (oop)r->bottom();
4979     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4980 
4981     // The following checks whether the humongous object is live are sufficient.
4982     // The main additional check (in addition to having a reference from the roots
4983     // or the young gen) is whether the humongous object has a remembered set entry.
4984     //
4985     // A humongous object cannot be live if there is no remembered set for it
4986     // because:
4987     // - there can be no references from within humongous starts regions referencing
4988     // the object because we never allocate other objects into them.
4989     // (I.e. there are no intra-region references that may be missed by the
4990     // remembered set)
4991     // - as soon there is a remembered set entry to the humongous starts region
4992     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4993     // until the end of a concurrent mark.
4994     //
4995     // It is not required to check whether the object has been found dead by marking
4996     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4997     // all objects allocated during that time are considered live.
4998     // SATB marking is even more conservative than the remembered set.
4999     // So if at this point in the collection there is no remembered set entry,
5000     // nobody has a reference to it.
5001     // At the start of collection we flush all refinement logs, and remembered sets
5002     // are completely up-to-date wrt to references to the humongous object.
5003     //
5004     // Other implementation considerations:
5005     // - never consider object arrays at this time because they would pose
5006     // considerable effort for cleaning up the the remembered sets. This is
5007     // required because stale remembered sets might reference locations that
5008     // are currently allocated into.
5009     uint region_idx = r->hrm_index();
5010     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5011         !r->rem_set()->is_empty()) {
5012       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",
5013                                region_idx,
5014                                (size_t)obj->size() * HeapWordSize,
5015                                p2i(r->bottom()),
5016                                r->rem_set()->occupied(),
5017                                r->rem_set()->strong_code_roots_list_length(),
5018                                next_bitmap->isMarked(r->bottom()),
5019                                g1h->is_humongous_reclaim_candidate(region_idx),
5020                                obj->is_typeArray()
5021                               );
5022       return false;
5023     }
5024 
5025     guarantee(obj->is_typeArray(),
5026               "Only eagerly reclaiming type arrays is supported, but the object "
5027               PTR_FORMAT " is not.", p2i(r->bottom()));
5028 
5029     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",
5030                              region_idx,
5031                              (size_t)obj->size() * HeapWordSize,
5032                              p2i(r->bottom()),
5033                              r->rem_set()->occupied(),
5034                              r->rem_set()->strong_code_roots_list_length(),
5035                              next_bitmap->isMarked(r->bottom()),
5036                              g1h->is_humongous_reclaim_candidate(region_idx),
5037                              obj->is_typeArray()
5038                             );
5039 
5040     // Need to clear mark bit of the humongous object if already set.
5041     if (next_bitmap->isMarked(r->bottom())) {
5042       next_bitmap->clear(r->bottom());
5043     }
5044     do {
5045       HeapRegion* next = g1h->next_region_in_humongous(r);
5046       _freed_bytes += r->used();
5047       r->set_containing_set(NULL);
5048       _humongous_regions_removed++;
5049       g1h->free_humongous_region(r, _free_region_list, false);
5050       r = next;
5051     } while (r != NULL);
5052 
5053     return false;
5054   }
5055 
5056   uint humongous_free_count() {
5057     return _humongous_regions_removed;
5058   }
5059 
5060   size_t bytes_freed() const {
5061     return _freed_bytes;
5062   }
5063 };
5064 
5065 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5066   assert_at_safepoint(true);
5067 
5068   if (!G1EagerReclaimHumongousObjects ||
5069       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5070     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5071     return;
5072   }
5073 
5074   double start_time = os::elapsedTime();
5075 
5076   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5077 
5078   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5079   heap_region_iterate(&cl);
5080 
5081   remove_from_old_sets(0, cl.humongous_free_count());
5082 
5083   G1HRPrinter* hrp = hr_printer();
5084   if (hrp->is_active()) {
5085     FreeRegionListIterator iter(&local_cleanup_list);
5086     while (iter.more_available()) {
5087       HeapRegion* hr = iter.get_next();
5088       hrp->cleanup(hr);
5089     }
5090   }
5091 
5092   prepend_to_freelist(&local_cleanup_list);
5093   decrement_summary_bytes(cl.bytes_freed());
5094 
5095   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5096                                                                     cl.humongous_free_count());
5097 }
5098 
5099 // This routine is similar to the above but does not record
5100 // any policy statistics or update free lists; we are abandoning
5101 // the current incremental collection set in preparation of a
5102 // full collection. After the full GC we will start to build up
5103 // the incremental collection set again.
5104 // This is only called when we're doing a full collection
5105 // and is immediately followed by the tearing down of the young list.
5106 
5107 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5108   HeapRegion* cur = cs_head;
5109 
5110   while (cur != NULL) {
5111     HeapRegion* next = cur->next_in_collection_set();
5112     assert(cur->in_collection_set(), "bad CS");
5113     cur->set_next_in_collection_set(NULL);
5114     clear_in_cset(cur);
5115     cur->set_young_index_in_cset(-1);
5116     cur = next;
5117   }
5118 }
5119 
5120 void G1CollectedHeap::set_free_regions_coming() {
5121   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5122 
5123   assert(!free_regions_coming(), "pre-condition");
5124   _free_regions_coming = true;
5125 }
5126 
5127 void G1CollectedHeap::reset_free_regions_coming() {
5128   assert(free_regions_coming(), "pre-condition");
5129 
5130   {
5131     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5132     _free_regions_coming = false;
5133     SecondaryFreeList_lock->notify_all();
5134   }
5135 
5136   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5137 }
5138 
5139 void G1CollectedHeap::wait_while_free_regions_coming() {
5140   // Most of the time we won't have to wait, so let's do a quick test
5141   // first before we take the lock.
5142   if (!free_regions_coming()) {
5143     return;
5144   }
5145 
5146   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5147 
5148   {
5149     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5150     while (free_regions_coming()) {
5151       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5152     }
5153   }
5154 
5155   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5156 }
5157 
5158 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5159   return _allocator->is_retained_old_region(hr);
5160 }
5161 
5162 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5163   _young_list->push_region(hr);
5164 }
5165 
5166 class NoYoungRegionsClosure: public HeapRegionClosure {
5167 private:
5168   bool _success;
5169 public:
5170   NoYoungRegionsClosure() : _success(true) { }
5171   bool doHeapRegion(HeapRegion* r) {
5172     if (r->is_young()) {
5173       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5174                             p2i(r->bottom()), p2i(r->end()));
5175       _success = false;
5176     }
5177     return false;
5178   }
5179   bool success() { return _success; }
5180 };
5181 
5182 bool G1CollectedHeap::check_young_list_empty(bool check_heap) {
5183   bool ret = _young_list->check_list_empty();
5184 
5185   if (check_heap) {
5186     NoYoungRegionsClosure closure;
5187     heap_region_iterate(&closure);
5188     ret = ret && closure.success();
5189   }
5190 
5191   return ret;
5192 }
5193 
5194 class TearDownRegionSetsClosure : public HeapRegionClosure {
5195 private:
5196   HeapRegionSet *_old_set;
5197 
5198 public:
5199   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5200 
5201   bool doHeapRegion(HeapRegion* r) {
5202     if (r->is_old()) {
5203       _old_set->remove(r);
5204     } else {
5205       // We ignore free regions, we'll empty the free list afterwards.
5206       // We ignore young regions, we'll empty the young list afterwards.
5207       // We ignore humongous regions, we're not tearing down the
5208       // humongous regions set.
5209       assert(r->is_free() || r->is_young() || r->is_humongous(),
5210              "it cannot be another type");
5211     }
5212     return false;
5213   }
5214 
5215   ~TearDownRegionSetsClosure() {
5216     assert(_old_set->is_empty(), "post-condition");
5217   }
5218 };
5219 
5220 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5221   assert_at_safepoint(true /* should_be_vm_thread */);
5222 
5223   if (!free_list_only) {
5224     TearDownRegionSetsClosure cl(&_old_set);
5225     heap_region_iterate(&cl);
5226 
5227     // Note that emptying the _young_list is postponed and instead done as
5228     // the first step when rebuilding the regions sets again. The reason for
5229     // this is that during a full GC string deduplication needs to know if
5230     // a collected region was young or old when the full GC was initiated.
5231   }
5232   _hrm.remove_all_free_regions();
5233 }
5234 
5235 void G1CollectedHeap::increase_used(size_t bytes) {
5236   _summary_bytes_used += bytes;
5237 }
5238 
5239 void G1CollectedHeap::decrease_used(size_t bytes) {
5240   assert(_summary_bytes_used >= bytes,
5241          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5242          _summary_bytes_used, bytes);
5243   _summary_bytes_used -= bytes;
5244 }
5245 
5246 void G1CollectedHeap::set_used(size_t bytes) {
5247   _summary_bytes_used = bytes;
5248 }
5249 
5250 class RebuildRegionSetsClosure : public HeapRegionClosure {
5251 private:
5252   bool            _free_list_only;
5253   HeapRegionSet*   _old_set;
5254   HeapRegionManager*   _hrm;
5255   size_t          _total_used;
5256 
5257 public:
5258   RebuildRegionSetsClosure(bool free_list_only,
5259                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5260     _free_list_only(free_list_only),
5261     _old_set(old_set), _hrm(hrm), _total_used(0) {
5262     assert(_hrm->num_free_regions() == 0, "pre-condition");
5263     if (!free_list_only) {
5264       assert(_old_set->is_empty(), "pre-condition");
5265     }
5266   }
5267 
5268   bool doHeapRegion(HeapRegion* r) {
5269     if (r->is_empty()) {
5270       // Add free regions to the free list
5271       r->set_free();
5272       r->set_allocation_context(AllocationContext::system());
5273       _hrm->insert_into_free_list(r);
5274     } else if (!_free_list_only) {
5275       assert(!r->is_young(), "we should not come across young regions");
5276 
5277       if (r->is_humongous()) {
5278         // We ignore humongous regions. We left the humongous set unchanged.
5279       } else {
5280         // Objects that were compacted would have ended up on regions
5281         // that were previously old or free.  Archive regions (which are
5282         // old) will not have been touched.
5283         assert(r->is_free() || r->is_old(), "invariant");
5284         // We now consider them old, so register as such. Leave
5285         // archive regions set that way, however, while still adding
5286         // them to the old set.
5287         if (!r->is_archive()) {
5288           r->set_old();
5289         }
5290         _old_set->add(r);
5291       }
5292       _total_used += r->used();
5293     }
5294 
5295     return false;
5296   }
5297 
5298   size_t total_used() {
5299     return _total_used;
5300   }
5301 };
5302 
5303 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5304   assert_at_safepoint(true /* should_be_vm_thread */);
5305 
5306   if (!free_list_only) {
5307     _young_list->empty_list();
5308   }
5309 
5310   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5311   heap_region_iterate(&cl);
5312 
5313   if (!free_list_only) {
5314     set_used(cl.total_used());
5315     if (_archive_allocator != NULL) {
5316       _archive_allocator->clear_used();
5317     }
5318   }
5319   assert(used_unlocked() == recalculate_used(),
5320          "inconsistent used_unlocked(), "
5321          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5322          used_unlocked(), recalculate_used());
5323 }
5324 
5325 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5326   _refine_cte_cl->set_concurrent(concurrent);
5327 }
5328 
5329 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5330   HeapRegion* hr = heap_region_containing(p);
5331   return hr->is_in(p);
5332 }
5333 
5334 // Methods for the mutator alloc region
5335 
5336 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5337                                                       bool force) {
5338   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5339   assert(!force || g1_policy()->can_expand_young_list(),
5340          "if force is true we should be able to expand the young list");
5341   bool young_list_full = g1_policy()->is_young_list_full();
5342   if (force || !young_list_full) {
5343     HeapRegion* new_alloc_region = new_region(word_size,
5344                                               false /* is_old */,
5345                                               false /* do_expand */);
5346     if (new_alloc_region != NULL) {
5347       set_region_short_lived_locked(new_alloc_region);
5348       _hr_printer.alloc(new_alloc_region, young_list_full);
5349       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5350       return new_alloc_region;
5351     }
5352   }
5353   return NULL;
5354 }
5355 
5356 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5357                                                   size_t allocated_bytes) {
5358   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5359   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5360 
5361   collection_set()->add_eden_region(alloc_region);
5362   increase_used(allocated_bytes);
5363   _hr_printer.retire(alloc_region);
5364   // We update the eden sizes here, when the region is retired,
5365   // instead of when it's allocated, since this is the point that its
5366   // used space has been recored in _summary_bytes_used.
5367   g1mm()->update_eden_size();
5368 }
5369 
5370 // Methods for the GC alloc regions
5371 
5372 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5373   if (dest.is_old()) {
5374     return true;
5375   } else {
5376     return young_list()->survivor_length() < g1_policy()->max_survivor_regions();
5377   }
5378 }
5379 
5380 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5381   assert(FreeList_lock->owned_by_self(), "pre-condition");
5382 
5383   if (!has_more_regions(dest)) {
5384     return NULL;
5385   }
5386 
5387   const bool is_survivor = dest.is_young();
5388 
5389   HeapRegion* new_alloc_region = new_region(word_size,
5390                                             !is_survivor,
5391                                             true /* do_expand */);
5392   if (new_alloc_region != NULL) {
5393     // We really only need to do this for old regions given that we
5394     // should never scan survivors. But it doesn't hurt to do it
5395     // for survivors too.
5396     new_alloc_region->record_timestamp();
5397     if (is_survivor) {
5398       new_alloc_region->set_survivor();
5399       young_list()->add_survivor_region(new_alloc_region);
5400       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5401     } else {
5402       new_alloc_region->set_old();
5403       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5404     }
5405     _hr_printer.alloc(new_alloc_region);
5406     bool during_im = collector_state()->during_initial_mark_pause();
5407     new_alloc_region->note_start_of_copying(during_im);
5408     return new_alloc_region;
5409   }
5410   return NULL;
5411 }
5412 
5413 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5414                                              size_t allocated_bytes,
5415                                              InCSetState dest) {
5416   bool during_im = collector_state()->during_initial_mark_pause();
5417   alloc_region->note_end_of_copying(during_im);
5418   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5419   if (dest.is_old()) {
5420     _old_set.add(alloc_region);
5421   }
5422   _hr_printer.retire(alloc_region);
5423 }
5424 
5425 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5426   bool expanded = false;
5427   uint index = _hrm.find_highest_free(&expanded);
5428 
5429   if (index != G1_NO_HRM_INDEX) {
5430     if (expanded) {
5431       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5432                                 HeapRegion::GrainWords * HeapWordSize);
5433     }
5434     _hrm.allocate_free_regions_starting_at(index, 1);
5435     return region_at(index);
5436   }
5437   return NULL;
5438 }
5439 
5440 // Optimized nmethod scanning
5441 
5442 class RegisterNMethodOopClosure: public OopClosure {
5443   G1CollectedHeap* _g1h;
5444   nmethod* _nm;
5445 
5446   template <class T> void do_oop_work(T* p) {
5447     T heap_oop = oopDesc::load_heap_oop(p);
5448     if (!oopDesc::is_null(heap_oop)) {
5449       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5450       HeapRegion* hr = _g1h->heap_region_containing(obj);
5451       assert(!hr->is_continues_humongous(),
5452              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5453              " starting at " HR_FORMAT,
5454              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5455 
5456       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5457       hr->add_strong_code_root_locked(_nm);
5458     }
5459   }
5460 
5461 public:
5462   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5463     _g1h(g1h), _nm(nm) {}
5464 
5465   void do_oop(oop* p)       { do_oop_work(p); }
5466   void do_oop(narrowOop* p) { do_oop_work(p); }
5467 };
5468 
5469 class UnregisterNMethodOopClosure: public OopClosure {
5470   G1CollectedHeap* _g1h;
5471   nmethod* _nm;
5472 
5473   template <class T> void do_oop_work(T* p) {
5474     T heap_oop = oopDesc::load_heap_oop(p);
5475     if (!oopDesc::is_null(heap_oop)) {
5476       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5477       HeapRegion* hr = _g1h->heap_region_containing(obj);
5478       assert(!hr->is_continues_humongous(),
5479              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5480              " starting at " HR_FORMAT,
5481              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5482 
5483       hr->remove_strong_code_root(_nm);
5484     }
5485   }
5486 
5487 public:
5488   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5489     _g1h(g1h), _nm(nm) {}
5490 
5491   void do_oop(oop* p)       { do_oop_work(p); }
5492   void do_oop(narrowOop* p) { do_oop_work(p); }
5493 };
5494 
5495 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5496   CollectedHeap::register_nmethod(nm);
5497 
5498   guarantee(nm != NULL, "sanity");
5499   RegisterNMethodOopClosure reg_cl(this, nm);
5500   nm->oops_do(&reg_cl);
5501 }
5502 
5503 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5504   CollectedHeap::unregister_nmethod(nm);
5505 
5506   guarantee(nm != NULL, "sanity");
5507   UnregisterNMethodOopClosure reg_cl(this, nm);
5508   nm->oops_do(&reg_cl, true);
5509 }
5510 
5511 void G1CollectedHeap::purge_code_root_memory() {
5512   double purge_start = os::elapsedTime();
5513   G1CodeRootSet::purge();
5514   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5515   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5516 }
5517 
5518 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5519   G1CollectedHeap* _g1h;
5520 
5521 public:
5522   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5523     _g1h(g1h) {}
5524 
5525   void do_code_blob(CodeBlob* cb) {
5526     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5527     if (nm == NULL) {
5528       return;
5529     }
5530 
5531     if (ScavengeRootsInCode) {
5532       _g1h->register_nmethod(nm);
5533     }
5534   }
5535 };
5536 
5537 void G1CollectedHeap::rebuild_strong_code_roots() {
5538   RebuildStrongCodeRootClosure blob_cl(this);
5539   CodeCache::blobs_do(&blob_cl);
5540 }