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/g1HeapTransition.hpp"
  43 #include "gc/g1/g1HeapVerifier.hpp"
  44 #include "gc/g1/g1MarkSweep.hpp"
  45 #include "gc/g1/g1OopClosures.inline.hpp"
  46 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  47 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  48 #include "gc/g1/g1RemSet.inline.hpp"
  49 #include "gc/g1/g1RootClosures.hpp"
  50 #include "gc/g1/g1RootProcessor.hpp"
  51 #include "gc/g1/g1StringDedup.hpp"
  52 #include "gc/g1/g1YCTypes.hpp"
  53 #include "gc/g1/heapRegion.inline.hpp"
  54 #include "gc/g1/heapRegionRemSet.hpp"
  55 #include "gc/g1/heapRegionSet.inline.hpp"
  56 #include "gc/g1/suspendibleThreadSet.hpp"
  57 #include "gc/g1/vm_operations_g1.hpp"
  58 #include "gc/shared/gcHeapSummary.hpp"
  59 #include "gc/shared/gcId.hpp"
  60 #include "gc/shared/gcLocker.inline.hpp"
  61 #include "gc/shared/gcTimer.hpp"
  62 #include "gc/shared/gcTrace.hpp"
  63 #include "gc/shared/gcTraceTime.inline.hpp"
  64 #include "gc/shared/generationSpec.hpp"
  65 #include "gc/shared/isGCActiveMark.hpp"
  66 #include "gc/shared/referenceProcessor.inline.hpp"
  67 #include "gc/shared/taskqueue.inline.hpp"
  68 #include "logging/log.hpp"
  69 #include "memory/allocation.hpp"
  70 #include "memory/iterator.hpp"

  71 #include "oops/oop.inline.hpp"
  72 #include "runtime/atomic.inline.hpp"
  73 #include "runtime/init.hpp"
  74 #include "runtime/orderAccess.inline.hpp"
  75 #include "runtime/vmThread.hpp"
  76 #include "utilities/globalDefinitions.hpp"
  77 #include "utilities/stack.inline.hpp"
  78 
  79 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  80 
  81 // INVARIANTS/NOTES
  82 //
  83 // All allocation activity covered by the G1CollectedHeap interface is
  84 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  85 // and allocate_new_tlab, which are the "entry" points to the
  86 // allocation code from the rest of the JVM.  (Note that this does not
  87 // apply to TLAB allocation, which is not part of this interface: it
  88 // is done by clients of this interface.)
  89 
  90 // Local to this file.
  91 
  92 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  93   bool _concurrent;
  94 public:
  95   RefineCardTableEntryClosure() : _concurrent(true) { }
  96 
  97   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
  98     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
  99     // This path is executed by the concurrent refine or mutator threads,
 100     // concurrently, and so we do not care if card_ptr contains references
 101     // that point into the collection set.
 102     assert(!oops_into_cset, "should be");
 103 
 104     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 105       // Caller will actually yield.
 106       return false;
 107     }
 108     // Otherwise, we finished successfully; return true.
 109     return true;
 110   }
 111 
 112   void set_concurrent(bool b) { _concurrent = b; }
 113 };
 114 
 115 
 116 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 117  private:
 118   size_t _num_dirtied;
 119   G1CollectedHeap* _g1h;
 120   G1SATBCardTableLoggingModRefBS* _g1_bs;
 121 
 122   HeapRegion* region_for_card(jbyte* card_ptr) const {
 123     return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
 124   }
 125 
 126   bool will_become_free(HeapRegion* hr) const {
 127     // A region will be freed by free_collection_set if the region is in the
 128     // collection set and has not had an evacuation failure.
 129     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 130   }
 131 
 132  public:
 133   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 134     _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
 135 
 136   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 137     HeapRegion* hr = region_for_card(card_ptr);
 138 
 139     // Should only dirty cards in regions that won't be freed.
 140     if (!will_become_free(hr)) {
 141       *card_ptr = CardTableModRefBS::dirty_card_val();
 142       _num_dirtied++;
 143     }
 144 
 145     return true;
 146   }
 147 
 148   size_t num_dirtied()   const { return _num_dirtied; }
 149 };
 150 
 151 
 152 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 153   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 154 }
 155 
 156 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 157   // The from card cache is not the memory that is actually committed. So we cannot
 158   // take advantage of the zero_filled parameter.
 159   reset_from_card_cache(start_idx, num_regions);
 160 }
 161 
 162 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 163 {
 164   // Claim the right to put the region on the dirty cards region list
 165   // by installing a self pointer.
 166   HeapRegion* next = hr->get_next_dirty_cards_region();
 167   if (next == NULL) {
 168     HeapRegion* res = (HeapRegion*)
 169       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 170                           NULL);
 171     if (res == NULL) {
 172       HeapRegion* head;
 173       do {
 174         // Put the region to the dirty cards region list.
 175         head = _dirty_cards_region_list;
 176         next = (HeapRegion*)
 177           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 178         if (next == head) {
 179           assert(hr->get_next_dirty_cards_region() == hr,
 180                  "hr->get_next_dirty_cards_region() != hr");
 181           if (next == NULL) {
 182             // The last region in the list points to itself.
 183             hr->set_next_dirty_cards_region(hr);
 184           } else {
 185             hr->set_next_dirty_cards_region(next);
 186           }
 187         }
 188       } while (next != head);
 189     }
 190   }
 191 }
 192 
 193 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 194 {
 195   HeapRegion* head;
 196   HeapRegion* hr;
 197   do {
 198     head = _dirty_cards_region_list;
 199     if (head == NULL) {
 200       return NULL;
 201     }
 202     HeapRegion* new_head = head->get_next_dirty_cards_region();
 203     if (head == new_head) {
 204       // The last region.
 205       new_head = NULL;
 206     }
 207     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 208                                           head);
 209   } while (hr != head);
 210   assert(hr != NULL, "invariant");
 211   hr->set_next_dirty_cards_region(NULL);
 212   return hr;
 213 }
 214 
 215 // Returns true if the reference points to an object that
 216 // can move in an incremental collection.
 217 bool G1CollectedHeap::is_scavengable(const void* p) {
 218   HeapRegion* hr = heap_region_containing(p);
 219   return !hr->is_pinned();
 220 }
 221 
 222 // Private methods.
 223 
 224 HeapRegion*
 225 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 226   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 227   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 228     if (!_secondary_free_list.is_empty()) {
 229       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 230                                       "secondary_free_list has %u entries",
 231                                       _secondary_free_list.length());
 232       // It looks as if there are free regions available on the
 233       // secondary_free_list. Let's move them to the free_list and try
 234       // again to allocate from it.
 235       append_secondary_free_list();
 236 
 237       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 238              "empty we should have moved at least one entry to the free_list");
 239       HeapRegion* res = _hrm.allocate_free_region(is_old);
 240       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 241                                       "allocated " HR_FORMAT " from secondary_free_list",
 242                                       HR_FORMAT_PARAMS(res));
 243       return res;
 244     }
 245 
 246     // Wait here until we get notified either when (a) there are no
 247     // more free regions coming or (b) some regions have been moved on
 248     // the secondary_free_list.
 249     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 250   }
 251 
 252   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 253                                   "could not allocate from secondary_free_list");
 254   return NULL;
 255 }
 256 
 257 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 258   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 259          "the only time we use this to allocate a humongous region is "
 260          "when we are allocating a single humongous region");
 261 
 262   HeapRegion* res;
 263   if (G1StressConcRegionFreeing) {
 264     if (!_secondary_free_list.is_empty()) {
 265       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 266                                       "forced to look at the secondary_free_list");
 267       res = new_region_try_secondary_free_list(is_old);
 268       if (res != NULL) {
 269         return res;
 270       }
 271     }
 272   }
 273 
 274   res = _hrm.allocate_free_region(is_old);
 275 
 276   if (res == NULL) {
 277     log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 278                                     "res == NULL, trying the secondary_free_list");
 279     res = new_region_try_secondary_free_list(is_old);
 280   }
 281   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 282     // Currently, only attempts to allocate GC alloc regions set
 283     // do_expand to true. So, we should only reach here during a
 284     // safepoint. If this assumption changes we might have to
 285     // reconsider the use of _expand_heap_after_alloc_failure.
 286     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 287 
 288     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 289                               word_size * HeapWordSize);
 290 
 291     if (expand(word_size * HeapWordSize)) {
 292       // Given that expand() succeeded in expanding the heap, and we
 293       // always expand the heap by an amount aligned to the heap
 294       // region size, the free list should in theory not be empty.
 295       // In either case allocate_free_region() will check for NULL.
 296       res = _hrm.allocate_free_region(is_old);
 297     } else {
 298       _expand_heap_after_alloc_failure = false;
 299     }
 300   }
 301   return res;
 302 }
 303 
 304 HeapWord*
 305 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 306                                                            uint num_regions,
 307                                                            size_t word_size,
 308                                                            AllocationContext_t context) {
 309   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 310   assert(is_humongous(word_size), "word_size should be humongous");
 311   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 312 
 313   // Index of last region in the series.
 314   uint last = first + num_regions - 1;
 315 
 316   // We need to initialize the region(s) we just discovered. This is
 317   // a bit tricky given that it can happen concurrently with
 318   // refinement threads refining cards on these regions and
 319   // potentially wanting to refine the BOT as they are scanning
 320   // those cards (this can happen shortly after a cleanup; see CR
 321   // 6991377). So we have to set up the region(s) carefully and in
 322   // a specific order.
 323 
 324   // The word size sum of all the regions we will allocate.
 325   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 326   assert(word_size <= word_size_sum, "sanity");
 327 
 328   // This will be the "starts humongous" region.
 329   HeapRegion* first_hr = region_at(first);
 330   // The header of the new object will be placed at the bottom of
 331   // the first region.
 332   HeapWord* new_obj = first_hr->bottom();
 333   // This will be the new top of the new object.
 334   HeapWord* obj_top = new_obj + word_size;
 335 
 336   // First, we need to zero the header of the space that we will be
 337   // allocating. When we update top further down, some refinement
 338   // threads might try to scan the region. By zeroing the header we
 339   // ensure that any thread that will try to scan the region will
 340   // come across the zero klass word and bail out.
 341   //
 342   // NOTE: It would not have been correct to have used
 343   // CollectedHeap::fill_with_object() and make the space look like
 344   // an int array. The thread that is doing the allocation will
 345   // later update the object header to a potentially different array
 346   // type and, for a very short period of time, the klass and length
 347   // fields will be inconsistent. This could cause a refinement
 348   // thread to calculate the object size incorrectly.
 349   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 350 
 351   // How many words we use for filler objects.
 352   size_t word_fill_size = word_size_sum - word_size;
 353 
 354   // How many words memory we "waste" which cannot hold a filler object.
 355   size_t words_not_fillable = 0;
 356 
 357   if (word_fill_size >= min_fill_size()) {
 358     fill_with_objects(obj_top, word_fill_size);
 359   } else if (word_fill_size > 0) {
 360     // We have space to fill, but we cannot fit an object there.
 361     words_not_fillable = word_fill_size;
 362     word_fill_size = 0;
 363   }
 364 
 365   // We will set up the first region as "starts humongous". This
 366   // will also update the BOT covering all the regions to reflect
 367   // that there is a single object that starts at the bottom of the
 368   // first region.
 369   first_hr->set_starts_humongous(obj_top, word_fill_size);
 370   first_hr->set_allocation_context(context);
 371   // Then, if there are any, we will set up the "continues
 372   // humongous" regions.
 373   HeapRegion* hr = NULL;
 374   for (uint i = first + 1; i <= last; ++i) {
 375     hr = region_at(i);
 376     hr->set_continues_humongous(first_hr);
 377     hr->set_allocation_context(context);
 378   }
 379 
 380   // Up to this point no concurrent thread would have been able to
 381   // do any scanning on any region in this series. All the top
 382   // fields still point to bottom, so the intersection between
 383   // [bottom,top] and [card_start,card_end] will be empty. Before we
 384   // update the top fields, we'll do a storestore to make sure that
 385   // no thread sees the update to top before the zeroing of the
 386   // object header and the BOT initialization.
 387   OrderAccess::storestore();
 388 
 389   // Now, we will update the top fields of the "continues humongous"
 390   // regions except the last one.
 391   for (uint i = first; i < last; ++i) {
 392     hr = region_at(i);
 393     hr->set_top(hr->end());
 394   }
 395 
 396   hr = region_at(last);
 397   // If we cannot fit a filler object, we must set top to the end
 398   // of the humongous object, otherwise we cannot iterate the heap
 399   // and the BOT will not be complete.
 400   hr->set_top(hr->end() - words_not_fillable);
 401 
 402   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 403          "obj_top should be in last region");
 404 
 405   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 406 
 407   assert(words_not_fillable == 0 ||
 408          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 409          "Miscalculation in humongous allocation");
 410 
 411   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 412 
 413   for (uint i = first; i <= last; ++i) {
 414     hr = region_at(i);
 415     _humongous_set.add(hr);
 416     _hr_printer.alloc(hr);
 417   }
 418 
 419   return new_obj;
 420 }
 421 
 422 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 423   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 424   return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 425 }
 426 
 427 // If could fit into free regions w/o expansion, try.
 428 // Otherwise, if can expand, do so.
 429 // Otherwise, if using ex regions might help, try with ex given back.
 430 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 431   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 432 
 433   _verifier->verify_region_sets_optional();
 434 
 435   uint first = G1_NO_HRM_INDEX;
 436   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 437 
 438   if (obj_regions == 1) {
 439     // Only one region to allocate, try to use a fast path by directly allocating
 440     // from the free lists. Do not try to expand here, we will potentially do that
 441     // later.
 442     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 443     if (hr != NULL) {
 444       first = hr->hrm_index();
 445     }
 446   } else {
 447     // We can't allocate humongous regions spanning more than one region while
 448     // cleanupComplete() is running, since some of the regions we find to be
 449     // empty might not yet be added to the free list. It is not straightforward
 450     // to know in which list they are on so that we can remove them. We only
 451     // need to do this if we need to allocate more than one region to satisfy the
 452     // current humongous allocation request. If we are only allocating one region
 453     // we use the one-region region allocation code (see above), that already
 454     // potentially waits for regions from the secondary free list.
 455     wait_while_free_regions_coming();
 456     append_secondary_free_list_if_not_empty_with_lock();
 457 
 458     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 459     // are lucky enough to find some.
 460     first = _hrm.find_contiguous_only_empty(obj_regions);
 461     if (first != G1_NO_HRM_INDEX) {
 462       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 463     }
 464   }
 465 
 466   if (first == G1_NO_HRM_INDEX) {
 467     // Policy: We could not find enough regions for the humongous object in the
 468     // free list. Look through the heap to find a mix of free and uncommitted regions.
 469     // If so, try expansion.
 470     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 471     if (first != G1_NO_HRM_INDEX) {
 472       // We found something. Make sure these regions are committed, i.e. expand
 473       // the heap. Alternatively we could do a defragmentation GC.
 474       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 475                                     word_size * HeapWordSize);
 476 
 477 
 478       _hrm.expand_at(first, obj_regions);
 479       g1_policy()->record_new_heap_size(num_regions());
 480 
 481 #ifdef ASSERT
 482       for (uint i = first; i < first + obj_regions; ++i) {
 483         HeapRegion* hr = region_at(i);
 484         assert(hr->is_free(), "sanity");
 485         assert(hr->is_empty(), "sanity");
 486         assert(is_on_master_free_list(hr), "sanity");
 487       }
 488 #endif
 489       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 490     } else {
 491       // Policy: Potentially trigger a defragmentation GC.
 492     }
 493   }
 494 
 495   HeapWord* result = NULL;
 496   if (first != G1_NO_HRM_INDEX) {
 497     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 498                                                        word_size, context);
 499     assert(result != NULL, "it should always return a valid result");
 500 
 501     // A successful humongous object allocation changes the used space
 502     // information of the old generation so we need to recalculate the
 503     // sizes and update the jstat counters here.
 504     g1mm()->update_sizes();
 505   }
 506 
 507   _verifier->verify_region_sets_optional();
 508 
 509   return result;
 510 }
 511 
 512 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 513   assert_heap_not_locked_and_not_at_safepoint();
 514   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 515 
 516   uint dummy_gc_count_before;
 517   uint dummy_gclocker_retry_count = 0;
 518   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 519 }
 520 
 521 HeapWord*
 522 G1CollectedHeap::mem_allocate(size_t word_size,
 523                               bool*  gc_overhead_limit_was_exceeded) {
 524   assert_heap_not_locked_and_not_at_safepoint();
 525 
 526   // Loop until the allocation is satisfied, or unsatisfied after GC.
 527   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 528     uint gc_count_before;
 529 
 530     HeapWord* result = NULL;
 531     if (!is_humongous(word_size)) {
 532       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 533     } else {
 534       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 535     }
 536     if (result != NULL) {
 537       return result;
 538     }
 539 
 540     // Create the garbage collection operation...
 541     VM_G1CollectForAllocation op(gc_count_before, word_size);
 542     op.set_allocation_context(AllocationContext::current());
 543 
 544     // ...and get the VM thread to execute it.
 545     VMThread::execute(&op);
 546 
 547     if (op.prologue_succeeded() && op.pause_succeeded()) {
 548       // If the operation was successful we'll return the result even
 549       // if it is NULL. If the allocation attempt failed immediately
 550       // after a Full GC, it's unlikely we'll be able to allocate now.
 551       HeapWord* result = op.result();
 552       if (result != NULL && !is_humongous(word_size)) {
 553         // Allocations that take place on VM operations do not do any
 554         // card dirtying and we have to do it here. We only have to do
 555         // this for non-humongous allocations, though.
 556         dirty_young_block(result, word_size);
 557       }
 558       return result;
 559     } else {
 560       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 561         return NULL;
 562       }
 563       assert(op.result() == NULL,
 564              "the result should be NULL if the VM op did not succeed");
 565     }
 566 
 567     // Give a warning if we seem to be looping forever.
 568     if ((QueuedAllocationWarningCount > 0) &&
 569         (try_count % QueuedAllocationWarningCount == 0)) {
 570       log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
 571     }
 572   }
 573 
 574   ShouldNotReachHere();
 575   return NULL;
 576 }
 577 
 578 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 579                                                    AllocationContext_t context,
 580                                                    uint* gc_count_before_ret,
 581                                                    uint* gclocker_retry_count_ret) {
 582   // Make sure you read the note in attempt_allocation_humongous().
 583 
 584   assert_heap_not_locked_and_not_at_safepoint();
 585   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 586          "be called for humongous allocation requests");
 587 
 588   // We should only get here after the first-level allocation attempt
 589   // (attempt_allocation()) failed to allocate.
 590 
 591   // We will loop until a) we manage to successfully perform the
 592   // allocation or b) we successfully schedule a collection which
 593   // fails to perform the allocation. b) is the only case when we'll
 594   // return NULL.
 595   HeapWord* result = NULL;
 596   for (int try_count = 1; /* we'll return */; try_count += 1) {
 597     bool should_try_gc;
 598     uint gc_count_before;
 599 
 600     {
 601       MutexLockerEx x(Heap_lock);
 602       result = _allocator->attempt_allocation_locked(word_size, context);
 603       if (result != NULL) {
 604         return result;
 605       }
 606 
 607       if (GCLocker::is_active_and_needs_gc()) {
 608         if (g1_policy()->can_expand_young_list()) {
 609           // No need for an ergo verbose message here,
 610           // can_expand_young_list() does this when it returns true.
 611           result = _allocator->attempt_allocation_force(word_size, context);
 612           if (result != NULL) {
 613             return result;
 614           }
 615         }
 616         should_try_gc = false;
 617       } else {
 618         // The GCLocker may not be active but the GCLocker initiated
 619         // GC may not yet have been performed (GCLocker::needs_gc()
 620         // returns true). In this case we do not try this GC and
 621         // wait until the GCLocker initiated GC is performed, and
 622         // then retry the allocation.
 623         if (GCLocker::needs_gc()) {
 624           should_try_gc = false;
 625         } else {
 626           // Read the GC count while still holding the Heap_lock.
 627           gc_count_before = total_collections();
 628           should_try_gc = true;
 629         }
 630       }
 631     }
 632 
 633     if (should_try_gc) {
 634       bool succeeded;
 635       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 636                                    GCCause::_g1_inc_collection_pause);
 637       if (result != NULL) {
 638         assert(succeeded, "only way to get back a non-NULL result");
 639         return result;
 640       }
 641 
 642       if (succeeded) {
 643         // If we get here we successfully scheduled a collection which
 644         // failed to allocate. No point in trying to allocate
 645         // further. We'll just return NULL.
 646         MutexLockerEx x(Heap_lock);
 647         *gc_count_before_ret = total_collections();
 648         return NULL;
 649       }
 650     } else {
 651       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 652         MutexLockerEx x(Heap_lock);
 653         *gc_count_before_ret = total_collections();
 654         return NULL;
 655       }
 656       // The GCLocker is either active or the GCLocker initiated
 657       // GC has not yet been performed. Stall until it is and
 658       // then retry the allocation.
 659       GCLocker::stall_until_clear();
 660       (*gclocker_retry_count_ret) += 1;
 661     }
 662 
 663     // We can reach here if we were unsuccessful in scheduling a
 664     // collection (because another thread beat us to it) or if we were
 665     // stalled due to the GC locker. In either can we should retry the
 666     // allocation attempt in case another thread successfully
 667     // performed a collection and reclaimed enough space. We do the
 668     // first attempt (without holding the Heap_lock) here and the
 669     // follow-on attempt will be at the start of the next loop
 670     // iteration (after taking the Heap_lock).
 671     result = _allocator->attempt_allocation(word_size, context);
 672     if (result != NULL) {
 673       return result;
 674     }
 675 
 676     // Give a warning if we seem to be looping forever.
 677     if ((QueuedAllocationWarningCount > 0) &&
 678         (try_count % QueuedAllocationWarningCount == 0)) {
 679       log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
 680                       "retries %d times", try_count);
 681     }
 682   }
 683 
 684   ShouldNotReachHere();
 685   return NULL;
 686 }
 687 
 688 void G1CollectedHeap::begin_archive_alloc_range() {
 689   assert_at_safepoint(true /* should_be_vm_thread */);
 690   if (_archive_allocator == NULL) {
 691     _archive_allocator = G1ArchiveAllocator::create_allocator(this);
 692   }
 693 }
 694 
 695 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 696   // Allocations in archive regions cannot be of a size that would be considered
 697   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 698   // may be different at archive-restore time.
 699   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 700 }
 701 
 702 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 703   assert_at_safepoint(true /* should_be_vm_thread */);
 704   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 705   if (is_archive_alloc_too_large(word_size)) {
 706     return NULL;
 707   }
 708   return _archive_allocator->archive_mem_allocate(word_size);
 709 }
 710 
 711 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 712                                               size_t end_alignment_in_bytes) {
 713   assert_at_safepoint(true /* should_be_vm_thread */);
 714   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 715 
 716   // Call complete_archive to do the real work, filling in the MemRegion
 717   // array with the archive regions.
 718   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 719   delete _archive_allocator;
 720   _archive_allocator = NULL;
 721 }
 722 
 723 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 724   assert(ranges != NULL, "MemRegion array NULL");
 725   assert(count != 0, "No MemRegions provided");
 726   MemRegion reserved = _hrm.reserved();
 727   for (size_t i = 0; i < count; i++) {
 728     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 729       return false;
 730     }
 731   }
 732   return true;
 733 }
 734 
 735 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
 736   assert(!is_init_completed(), "Expect to be called at JVM init time");
 737   assert(ranges != NULL, "MemRegion array NULL");
 738   assert(count != 0, "No MemRegions provided");
 739   MutexLockerEx x(Heap_lock);
 740 
 741   MemRegion reserved = _hrm.reserved();
 742   HeapWord* prev_last_addr = NULL;
 743   HeapRegion* prev_last_region = NULL;
 744 
 745   // Temporarily disable pretouching of heap pages. This interface is used
 746   // when mmap'ing archived heap data in, so pre-touching is wasted.
 747   FlagSetting fs(AlwaysPreTouch, false);
 748 
 749   // Enable archive object checking in G1MarkSweep. We have to let it know
 750   // about each archive range, so that objects in those ranges aren't marked.
 751   G1MarkSweep::enable_archive_object_check();
 752 
 753   // For each specified MemRegion range, allocate the corresponding G1
 754   // regions and mark them as archive regions. We expect the ranges in
 755   // ascending starting address order, without overlap.
 756   for (size_t i = 0; i < count; i++) {
 757     MemRegion curr_range = ranges[i];
 758     HeapWord* start_address = curr_range.start();
 759     size_t word_size = curr_range.word_size();
 760     HeapWord* last_address = curr_range.last();
 761     size_t commits = 0;
 762 
 763     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 764               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 765               p2i(start_address), p2i(last_address));
 766     guarantee(start_address > prev_last_addr,
 767               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 768               p2i(start_address), p2i(prev_last_addr));
 769     prev_last_addr = last_address;
 770 
 771     // Check for ranges that start in the same G1 region in which the previous
 772     // range ended, and adjust the start address so we don't try to allocate
 773     // the same region again. If the current range is entirely within that
 774     // region, skip it, just adjusting the recorded top.
 775     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 776     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 777       start_address = start_region->end();
 778       if (start_address > last_address) {
 779         increase_used(word_size * HeapWordSize);
 780         start_region->set_top(last_address + 1);
 781         continue;
 782       }
 783       start_region->set_top(start_address);
 784       curr_range = MemRegion(start_address, last_address + 1);
 785       start_region = _hrm.addr_to_region(start_address);
 786     }
 787 
 788     // Perform the actual region allocation, exiting if it fails.
 789     // Then note how much new space we have allocated.
 790     if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
 791       return false;
 792     }
 793     increase_used(word_size * HeapWordSize);
 794     if (commits != 0) {
 795       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 796                                 HeapRegion::GrainWords * HeapWordSize * commits);
 797 
 798     }
 799 
 800     // Mark each G1 region touched by the range as archive, add it to the old set,
 801     // and set the allocation context and top.
 802     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 803     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 804     prev_last_region = last_region;
 805 
 806     while (curr_region != NULL) {
 807       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 808              "Region already in use (index %u)", curr_region->hrm_index());
 809       curr_region->set_allocation_context(AllocationContext::system());
 810       curr_region->set_archive();
 811       _hr_printer.alloc(curr_region);
 812       _old_set.add(curr_region);
 813       if (curr_region != last_region) {
 814         curr_region->set_top(curr_region->end());
 815         curr_region = _hrm.next_region_in_heap(curr_region);
 816       } else {
 817         curr_region->set_top(last_address + 1);
 818         curr_region = NULL;
 819       }
 820     }
 821 
 822     // Notify mark-sweep of the archive range.
 823     G1MarkSweep::set_range_archive(curr_range, true);
 824   }
 825   return true;
 826 }
 827 
 828 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 829   assert(!is_init_completed(), "Expect to be called at JVM init time");
 830   assert(ranges != NULL, "MemRegion array NULL");
 831   assert(count != 0, "No MemRegions provided");
 832   MemRegion reserved = _hrm.reserved();
 833   HeapWord *prev_last_addr = NULL;
 834   HeapRegion* prev_last_region = NULL;
 835 
 836   // For each MemRegion, create filler objects, if needed, in the G1 regions
 837   // that contain the address range. The address range actually within the
 838   // MemRegion will not be modified. That is assumed to have been initialized
 839   // elsewhere, probably via an mmap of archived heap data.
 840   MutexLockerEx x(Heap_lock);
 841   for (size_t i = 0; i < count; i++) {
 842     HeapWord* start_address = ranges[i].start();
 843     HeapWord* last_address = ranges[i].last();
 844 
 845     assert(reserved.contains(start_address) && reserved.contains(last_address),
 846            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 847            p2i(start_address), p2i(last_address));
 848     assert(start_address > prev_last_addr,
 849            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 850            p2i(start_address), p2i(prev_last_addr));
 851 
 852     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 853     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 854     HeapWord* bottom_address = start_region->bottom();
 855 
 856     // Check for a range beginning in the same region in which the
 857     // previous one ended.
 858     if (start_region == prev_last_region) {
 859       bottom_address = prev_last_addr + 1;
 860     }
 861 
 862     // Verify that the regions were all marked as archive regions by
 863     // alloc_archive_regions.
 864     HeapRegion* curr_region = start_region;
 865     while (curr_region != NULL) {
 866       guarantee(curr_region->is_archive(),
 867                 "Expected archive region at index %u", curr_region->hrm_index());
 868       if (curr_region != last_region) {
 869         curr_region = _hrm.next_region_in_heap(curr_region);
 870       } else {
 871         curr_region = NULL;
 872       }
 873     }
 874 
 875     prev_last_addr = last_address;
 876     prev_last_region = last_region;
 877 
 878     // Fill the memory below the allocated range with dummy object(s),
 879     // if the region bottom does not match the range start, or if the previous
 880     // range ended within the same G1 region, and there is a gap.
 881     if (start_address != bottom_address) {
 882       size_t fill_size = pointer_delta(start_address, bottom_address);
 883       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 884       increase_used(fill_size * HeapWordSize);
 885     }
 886   }
 887 }
 888 
 889 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
 890                                                      uint* gc_count_before_ret,
 891                                                      uint* gclocker_retry_count_ret) {
 892   assert_heap_not_locked_and_not_at_safepoint();
 893   assert(!is_humongous(word_size), "attempt_allocation() should not "
 894          "be called for humongous allocation requests");
 895 
 896   AllocationContext_t context = AllocationContext::current();
 897   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 898 
 899   if (result == NULL) {
 900     result = attempt_allocation_slow(word_size,
 901                                      context,
 902                                      gc_count_before_ret,
 903                                      gclocker_retry_count_ret);
 904   }
 905   assert_heap_not_locked();
 906   if (result != NULL) {
 907     dirty_young_block(result, word_size);
 908   }
 909   return result;
 910 }
 911 
 912 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 913   assert(!is_init_completed(), "Expect to be called at JVM init time");
 914   assert(ranges != NULL, "MemRegion array NULL");
 915   assert(count != 0, "No MemRegions provided");
 916   MemRegion reserved = _hrm.reserved();
 917   HeapWord* prev_last_addr = NULL;
 918   HeapRegion* prev_last_region = NULL;
 919   size_t size_used = 0;
 920   size_t uncommitted_regions = 0;
 921 
 922   // For each Memregion, free the G1 regions that constitute it, and
 923   // notify mark-sweep that the range is no longer to be considered 'archive.'
 924   MutexLockerEx x(Heap_lock);
 925   for (size_t i = 0; i < count; i++) {
 926     HeapWord* start_address = ranges[i].start();
 927     HeapWord* last_address = ranges[i].last();
 928 
 929     assert(reserved.contains(start_address) && reserved.contains(last_address),
 930            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 931            p2i(start_address), p2i(last_address));
 932     assert(start_address > prev_last_addr,
 933            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 934            p2i(start_address), p2i(prev_last_addr));
 935     size_used += ranges[i].byte_size();
 936     prev_last_addr = last_address;
 937 
 938     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 939     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 940 
 941     // Check for ranges that start in the same G1 region in which the previous
 942     // range ended, and adjust the start address so we don't try to free
 943     // the same region again. If the current range is entirely within that
 944     // region, skip it.
 945     if (start_region == prev_last_region) {
 946       start_address = start_region->end();
 947       if (start_address > last_address) {
 948         continue;
 949       }
 950       start_region = _hrm.addr_to_region(start_address);
 951     }
 952     prev_last_region = last_region;
 953 
 954     // After verifying that each region was marked as an archive region by
 955     // alloc_archive_regions, set it free and empty and uncommit it.
 956     HeapRegion* curr_region = start_region;
 957     while (curr_region != NULL) {
 958       guarantee(curr_region->is_archive(),
 959                 "Expected archive region at index %u", curr_region->hrm_index());
 960       uint curr_index = curr_region->hrm_index();
 961       _old_set.remove(curr_region);
 962       curr_region->set_free();
 963       curr_region->set_top(curr_region->bottom());
 964       if (curr_region != last_region) {
 965         curr_region = _hrm.next_region_in_heap(curr_region);
 966       } else {
 967         curr_region = NULL;
 968       }
 969       _hrm.shrink_at(curr_index, 1);
 970       uncommitted_regions++;
 971     }
 972 
 973     // Notify mark-sweep that this is no longer an archive range.
 974     G1MarkSweep::set_range_archive(ranges[i], false);
 975   }
 976 
 977   if (uncommitted_regions != 0) {
 978     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 979                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 980   }
 981   decrease_used(size_used);
 982 }
 983 
 984 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 985                                                         uint* gc_count_before_ret,
 986                                                         uint* gclocker_retry_count_ret) {
 987   // The structure of this method has a lot of similarities to
 988   // attempt_allocation_slow(). The reason these two were not merged
 989   // into a single one is that such a method would require several "if
 990   // allocation is not humongous do this, otherwise do that"
 991   // conditional paths which would obscure its flow. In fact, an early
 992   // version of this code did use a unified method which was harder to
 993   // follow and, as a result, it had subtle bugs that were hard to
 994   // track down. So keeping these two methods separate allows each to
 995   // be more readable. It will be good to keep these two in sync as
 996   // much as possible.
 997 
 998   assert_heap_not_locked_and_not_at_safepoint();
 999   assert(is_humongous(word_size), "attempt_allocation_humongous() "
1000          "should only be called for humongous allocations");
1001 
1002   // Humongous objects can exhaust the heap quickly, so we should check if we
1003   // need to start a marking cycle at each humongous object allocation. We do
1004   // the check before we do the actual allocation. The reason for doing it
1005   // before the allocation is that we avoid having to keep track of the newly
1006   // allocated memory while we do a GC.
1007   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1008                                            word_size)) {
1009     collect(GCCause::_g1_humongous_allocation);
1010   }
1011 
1012   // We will loop until a) we manage to successfully perform the
1013   // allocation or b) we successfully schedule a collection which
1014   // fails to perform the allocation. b) is the only case when we'll
1015   // return NULL.
1016   HeapWord* result = NULL;
1017   for (int try_count = 1; /* we'll return */; try_count += 1) {
1018     bool should_try_gc;
1019     uint gc_count_before;
1020 
1021     {
1022       MutexLockerEx x(Heap_lock);
1023 
1024       // Given that humongous objects are not allocated in young
1025       // regions, we'll first try to do the allocation without doing a
1026       // collection hoping that there's enough space in the heap.
1027       result = humongous_obj_allocate(word_size, AllocationContext::current());
1028       if (result != NULL) {
1029         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1030         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1031         return result;
1032       }
1033 
1034       if (GCLocker::is_active_and_needs_gc()) {
1035         should_try_gc = false;
1036       } else {
1037          // The GCLocker may not be active but the GCLocker initiated
1038         // GC may not yet have been performed (GCLocker::needs_gc()
1039         // returns true). In this case we do not try this GC and
1040         // wait until the GCLocker initiated GC is performed, and
1041         // then retry the allocation.
1042         if (GCLocker::needs_gc()) {
1043           should_try_gc = false;
1044         } else {
1045           // Read the GC count while still holding the Heap_lock.
1046           gc_count_before = total_collections();
1047           should_try_gc = true;
1048         }
1049       }
1050     }
1051 
1052     if (should_try_gc) {
1053       // If we failed to allocate the humongous object, we should try to
1054       // do a collection pause (if we're allowed) in case it reclaims
1055       // enough space for the allocation to succeed after the pause.
1056 
1057       bool succeeded;
1058       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1059                                    GCCause::_g1_humongous_allocation);
1060       if (result != NULL) {
1061         assert(succeeded, "only way to get back a non-NULL result");
1062         return result;
1063       }
1064 
1065       if (succeeded) {
1066         // If we get here we successfully scheduled a collection which
1067         // failed to allocate. No point in trying to allocate
1068         // further. We'll just return NULL.
1069         MutexLockerEx x(Heap_lock);
1070         *gc_count_before_ret = total_collections();
1071         return NULL;
1072       }
1073     } else {
1074       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1075         MutexLockerEx x(Heap_lock);
1076         *gc_count_before_ret = total_collections();
1077         return NULL;
1078       }
1079       // The GCLocker is either active or the GCLocker initiated
1080       // GC has not yet been performed. Stall until it is and
1081       // then retry the allocation.
1082       GCLocker::stall_until_clear();
1083       (*gclocker_retry_count_ret) += 1;
1084     }
1085 
1086     // We can reach here if we were unsuccessful in scheduling a
1087     // collection (because another thread beat us to it) or if we were
1088     // stalled due to the GC locker. In either can we should retry the
1089     // allocation attempt in case another thread successfully
1090     // performed a collection and reclaimed enough space.  Give a
1091     // warning if we seem to be looping forever.
1092 
1093     if ((QueuedAllocationWarningCount > 0) &&
1094         (try_count % QueuedAllocationWarningCount == 0)) {
1095       log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1096                       "retries %d times", try_count);
1097     }
1098   }
1099 
1100   ShouldNotReachHere();
1101   return NULL;
1102 }
1103 
1104 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1105                                                            AllocationContext_t context,
1106                                                            bool expect_null_mutator_alloc_region) {
1107   assert_at_safepoint(true /* should_be_vm_thread */);
1108   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1109          "the current alloc region was unexpectedly found to be non-NULL");
1110 
1111   if (!is_humongous(word_size)) {
1112     return _allocator->attempt_allocation_locked(word_size, context);
1113   } else {
1114     HeapWord* result = humongous_obj_allocate(word_size, context);
1115     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1116       collector_state()->set_initiate_conc_mark_if_possible(true);
1117     }
1118     return result;
1119   }
1120 
1121   ShouldNotReachHere();
1122 }
1123 
1124 class PostMCRemSetClearClosure: public HeapRegionClosure {
1125   G1CollectedHeap* _g1h;
1126   ModRefBarrierSet* _mr_bs;
1127 public:
1128   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1129     _g1h(g1h), _mr_bs(mr_bs) {}
1130 
1131   bool doHeapRegion(HeapRegion* r) {
1132     HeapRegionRemSet* hrrs = r->rem_set();
1133 
1134     _g1h->reset_gc_time_stamps(r);
1135 
1136     if (r->is_continues_humongous()) {
1137       // We'll assert that the strong code root list and RSet is empty
1138       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1139       assert(hrrs->occupied() == 0, "RSet should be empty");
1140     } else {
1141       hrrs->clear();
1142     }
1143     // You might think here that we could clear just the cards
1144     // corresponding to the used region.  But no: if we leave a dirty card
1145     // in a region we might allocate into, then it would prevent that card
1146     // from being enqueued, and cause it to be missed.
1147     // Re: the performance cost: we shouldn't be doing full GC anyway!
1148     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1149 
1150     return false;
1151   }
1152 };
1153 
1154 void G1CollectedHeap::clear_rsets_post_compaction() {
1155   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1156   heap_region_iterate(&rs_clear);
1157 }
1158 
1159 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1160   G1CollectedHeap*   _g1h;
1161   UpdateRSOopClosure _cl;
1162 public:
1163   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1164     _cl(g1->g1_rem_set(), worker_i),
1165     _g1h(g1)
1166   { }
1167 
1168   bool doHeapRegion(HeapRegion* r) {
1169     if (!r->is_continues_humongous()) {
1170       _cl.set_from(r);
1171       r->oop_iterate(&_cl);
1172     }
1173     return false;
1174   }
1175 };
1176 
1177 class ParRebuildRSTask: public AbstractGangTask {
1178   G1CollectedHeap* _g1;
1179   HeapRegionClaimer _hrclaimer;
1180 
1181 public:
1182   ParRebuildRSTask(G1CollectedHeap* g1) :
1183       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1184 
1185   void work(uint worker_id) {
1186     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1187     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1188   }
1189 };
1190 
1191 class PostCompactionPrinterClosure: public HeapRegionClosure {
1192 private:
1193   G1HRPrinter* _hr_printer;
1194 public:
1195   bool doHeapRegion(HeapRegion* hr) {
1196     assert(!hr->is_young(), "not expecting to find young regions");
1197     _hr_printer->post_compaction(hr);
1198     return false;
1199   }
1200 
1201   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1202     : _hr_printer(hr_printer) { }
1203 };
1204 
1205 void G1CollectedHeap::print_hrm_post_compaction() {
1206   if (_hr_printer.is_active()) {
1207     PostCompactionPrinterClosure cl(hr_printer());
1208     heap_region_iterate(&cl);
1209   }
1210 
1211 }
1212 
1213 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1214                                          bool clear_all_soft_refs) {
1215   assert_at_safepoint(true /* should_be_vm_thread */);
1216 
1217   if (GCLocker::check_active_before_gc()) {
1218     return false;
1219   }
1220 
1221   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1222   gc_timer->register_gc_start();
1223 
1224   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1225   GCIdMark gc_id_mark;
1226   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1227 
1228   SvcGCMarker sgcm(SvcGCMarker::FULL);
1229   ResourceMark rm;
1230 
1231   print_heap_before_gc();
1232   print_heap_regions();
1233   trace_heap_before_gc(gc_tracer);
1234 
1235   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1236 
1237   _verifier->verify_region_sets_optional();
1238 
1239   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1240                            collector_policy()->should_clear_all_soft_refs();
1241 
1242   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1243 
1244   {
1245     IsGCActiveMark x;
1246 
1247     // Timing
1248     assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1249     GCTraceCPUTime tcpu;
1250 
1251     {
1252       GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1253       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1254       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1255 
1256       G1HeapTransition heap_transition(this);
1257       g1_policy()->record_full_collection_start();
1258 
1259       // Note: When we have a more flexible GC logging framework that
1260       // allows us to add optional attributes to a GC log record we
1261       // could consider timing and reporting how long we wait in the
1262       // following two methods.
1263       wait_while_free_regions_coming();
1264       // If we start the compaction before the CM threads finish
1265       // scanning the root regions we might trip them over as we'll
1266       // be moving objects / updating references. So let's wait until
1267       // they are done. By telling them to abort, they should complete
1268       // early.
1269       _cm->root_regions()->abort();
1270       _cm->root_regions()->wait_until_scan_finished();
1271       append_secondary_free_list_if_not_empty_with_lock();
1272 
1273       gc_prologue(true);
1274       increment_total_collections(true /* full gc */);
1275       increment_old_marking_cycles_started();
1276 
1277       assert(used() == recalculate_used(), "Should be equal");
1278 
1279       _verifier->verify_before_gc();
1280 
1281       _verifier->check_bitmaps("Full GC Start");
1282       pre_full_gc_dump(gc_timer);
1283 
1284 #if defined(COMPILER2) || INCLUDE_JVMCI
1285       DerivedPointerTable::clear();
1286 #endif
1287 
1288       // Disable discovery and empty the discovered lists
1289       // for the CM ref processor.
1290       ref_processor_cm()->disable_discovery();
1291       ref_processor_cm()->abandon_partial_discovery();
1292       ref_processor_cm()->verify_no_references_recorded();
1293 
1294       // Abandon current iterations of concurrent marking and concurrent
1295       // refinement, if any are in progress.
1296       concurrent_mark()->abort();
1297 
1298       // Make sure we'll choose a new allocation region afterwards.
1299       _allocator->release_mutator_alloc_region();
1300       _allocator->abandon_gc_alloc_regions();
1301       g1_rem_set()->cleanupHRRS();
1302 
1303       // We may have added regions to the current incremental collection
1304       // set between the last GC or pause and now. We need to clear the
1305       // incremental collection set and then start rebuilding it afresh
1306       // after this full GC.
1307       abandon_collection_set(collection_set()->inc_head());
1308       collection_set()->clear_incremental();
1309       collection_set()->stop_incremental_building();
1310 
1311       tear_down_region_sets(false /* free_list_only */);
1312       collector_state()->set_gcs_are_young(true);
1313 
1314       // See the comments in g1CollectedHeap.hpp and
1315       // G1CollectedHeap::ref_processing_init() about
1316       // how reference processing currently works in G1.
1317 
1318       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1319       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1320 
1321       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1322       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1323 
1324       ref_processor_stw()->enable_discovery();
1325       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1326 
1327       // Do collection work
1328       {
1329         HandleMark hm;  // Discard invalid handles created during gc
1330         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1331       }
1332 
1333       assert(num_free_regions() == 0, "we should not have added any free regions");
1334       rebuild_region_sets(false /* free_list_only */);
1335 
1336       // Enqueue any discovered reference objects that have
1337       // not been removed from the discovered lists.
1338       ref_processor_stw()->enqueue_discovered_references();
1339 
1340 #if defined(COMPILER2) || INCLUDE_JVMCI
1341       DerivedPointerTable::update_pointers();
1342 #endif
1343 
1344       MemoryService::track_memory_usage();
1345 
1346       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1347       ref_processor_stw()->verify_no_references_recorded();
1348 
1349       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1350       ClassLoaderDataGraph::purge();
1351       MetaspaceAux::verify_metrics();
1352 
1353       // Note: since we've just done a full GC, concurrent
1354       // marking is no longer active. Therefore we need not
1355       // re-enable reference discovery for the CM ref processor.
1356       // That will be done at the start of the next marking cycle.
1357       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1358       ref_processor_cm()->verify_no_references_recorded();
1359 
1360       reset_gc_time_stamp();
1361       // Since everything potentially moved, we will clear all remembered
1362       // sets, and clear all cards.  Later we will rebuild remembered
1363       // sets. We will also reset the GC time stamps of the regions.
1364       clear_rsets_post_compaction();
1365       check_gc_time_stamps();
1366 
1367       resize_if_necessary_after_full_collection();
1368 
1369       // We should do this after we potentially resize the heap so
1370       // that all the COMMIT / UNCOMMIT events are generated before
1371       // the compaction events.
1372       print_hrm_post_compaction();
1373 
1374       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1375       if (hot_card_cache->use_cache()) {
1376         hot_card_cache->reset_card_counts();
1377         hot_card_cache->reset_hot_cache();
1378       }
1379 
1380       // Rebuild remembered sets of all regions.
1381       uint n_workers =
1382         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1383                                                 workers()->active_workers(),
1384                                                 Threads::number_of_non_daemon_threads());
1385       workers()->set_active_workers(n_workers);
1386 
1387       ParRebuildRSTask rebuild_rs_task(this);
1388       workers()->run_task(&rebuild_rs_task);
1389 
1390       // Rebuild the strong code root lists for each region
1391       rebuild_strong_code_roots();
1392 
1393       if (true) { // FIXME
1394         MetaspaceGC::compute_new_size();
1395       }
1396 
1397 #ifdef TRACESPINNING
1398       ParallelTaskTerminator::print_termination_counts();
1399 #endif
1400 
1401       // Discard all rset updates
1402       JavaThread::dirty_card_queue_set().abandon_logs();
1403       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1404 
1405       // At this point there should be no regions in the
1406       // entire heap tagged as young.
1407       assert(check_young_list_empty(true /* check_heap */),
1408              "young list should be empty at this point");
1409 
1410       // Update the number of full collections that have been completed.
1411       increment_old_marking_cycles_completed(false /* concurrent */);
1412 
1413       _hrm.verify_optional();
1414       _verifier->verify_region_sets_optional();
1415 
1416       _verifier->verify_after_gc();
1417 
1418       // Clear the previous marking bitmap, if needed for bitmap verification.
1419       // Note we cannot do this when we clear the next marking bitmap in
1420       // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1421       // objects marked during a full GC against the previous bitmap.
1422       // But we need to clear it before calling check_bitmaps below since
1423       // the full GC has compacted objects and updated TAMS but not updated
1424       // the prev bitmap.
1425       if (G1VerifyBitmaps) {
1426         ((G1CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1427       }
1428       _verifier->check_bitmaps("Full GC End");
1429 
1430       // Start a new incremental collection set for the next pause
1431       assert(collection_set()->head() == NULL, "must be");
1432       collection_set()->start_incremental_building();
1433 
1434       clear_cset_fast_test();
1435 
1436       _allocator->init_mutator_alloc_region();
1437 
1438       g1_policy()->record_full_collection_end();
1439 
1440       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1441       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1442       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1443       // before any GC notifications are raised.
1444       g1mm()->update_sizes();
1445 
1446       gc_epilogue(true);
1447 
1448       heap_transition.print();
1449 
1450       print_heap_after_gc();
1451       print_heap_regions();
1452       trace_heap_after_gc(gc_tracer);
1453 
1454       post_full_gc_dump(gc_timer);
1455     }
1456 
1457     gc_timer->register_gc_end();
1458     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1459   }
1460 
1461   return true;
1462 }
1463 
1464 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1465   // Currently, there is no facility in the do_full_collection(bool) API to notify
1466   // the caller that the collection did not succeed (e.g., because it was locked
1467   // out by the GC locker). So, right now, we'll ignore the return value.
1468   bool dummy = do_full_collection(true,                /* explicit_gc */
1469                                   clear_all_soft_refs);
1470 }
1471 
1472 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1473   // Include bytes that will be pre-allocated to support collections, as "used".
1474   const size_t used_after_gc = used();
1475   const size_t capacity_after_gc = capacity();
1476   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1477 
1478   // This is enforced in arguments.cpp.
1479   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1480          "otherwise the code below doesn't make sense");
1481 
1482   // We don't have floating point command-line arguments
1483   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1484   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1485   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1486   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1487 
1488   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1489   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1490 
1491   // We have to be careful here as these two calculations can overflow
1492   // 32-bit size_t's.
1493   double used_after_gc_d = (double) used_after_gc;
1494   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1495   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1496 
1497   // Let's make sure that they are both under the max heap size, which
1498   // by default will make them fit into a size_t.
1499   double desired_capacity_upper_bound = (double) max_heap_size;
1500   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1501                                     desired_capacity_upper_bound);
1502   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1503                                     desired_capacity_upper_bound);
1504 
1505   // We can now safely turn them into size_t's.
1506   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1507   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1508 
1509   // This assert only makes sense here, before we adjust them
1510   // with respect to the min and max heap size.
1511   assert(minimum_desired_capacity <= maximum_desired_capacity,
1512          "minimum_desired_capacity = " SIZE_FORMAT ", "
1513          "maximum_desired_capacity = " SIZE_FORMAT,
1514          minimum_desired_capacity, maximum_desired_capacity);
1515 
1516   // Should not be greater than the heap max size. No need to adjust
1517   // it with respect to the heap min size as it's a lower bound (i.e.,
1518   // we'll try to make the capacity larger than it, not smaller).
1519   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1520   // Should not be less than the heap min size. No need to adjust it
1521   // with respect to the heap max size as it's an upper bound (i.e.,
1522   // we'll try to make the capacity smaller than it, not greater).
1523   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1524 
1525   if (capacity_after_gc < minimum_desired_capacity) {
1526     // Don't expand unless it's significant
1527     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1528 
1529     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1530                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1531                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1532 
1533     expand(expand_bytes);
1534 
1535     // No expansion, now see if we want to shrink
1536   } else if (capacity_after_gc > maximum_desired_capacity) {
1537     // Capacity too large, compute shrinking size
1538     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1539 
1540     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1541                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1542                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1543 
1544     shrink(shrink_bytes);
1545   }
1546 }
1547 
1548 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1549                                                             AllocationContext_t context,
1550                                                             bool do_gc,
1551                                                             bool clear_all_soft_refs,
1552                                                             bool expect_null_mutator_alloc_region,
1553                                                             bool* gc_succeeded) {
1554   *gc_succeeded = true;
1555   // Let's attempt the allocation first.
1556   HeapWord* result =
1557     attempt_allocation_at_safepoint(word_size,
1558                                     context,
1559                                     expect_null_mutator_alloc_region);
1560   if (result != NULL) {
1561     assert(*gc_succeeded, "sanity");
1562     return result;
1563   }
1564 
1565   // In a G1 heap, we're supposed to keep allocation from failing by
1566   // incremental pauses.  Therefore, at least for now, we'll favor
1567   // expansion over collection.  (This might change in the future if we can
1568   // do something smarter than full collection to satisfy a failed alloc.)
1569   result = expand_and_allocate(word_size, context);
1570   if (result != NULL) {
1571     assert(*gc_succeeded, "sanity");
1572     return result;
1573   }
1574 
1575   if (do_gc) {
1576     // Expansion didn't work, we'll try to do a Full GC.
1577     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1578                                        clear_all_soft_refs);
1579   }
1580 
1581   return NULL;
1582 }
1583 
1584 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1585                                                      AllocationContext_t context,
1586                                                      bool* succeeded) {
1587   assert_at_safepoint(true /* should_be_vm_thread */);
1588 
1589   // Attempts to allocate followed by Full GC.
1590   HeapWord* result =
1591     satisfy_failed_allocation_helper(word_size,
1592                                      context,
1593                                      true,  /* do_gc */
1594                                      false, /* clear_all_soft_refs */
1595                                      false, /* expect_null_mutator_alloc_region */
1596                                      succeeded);
1597 
1598   if (result != NULL || !*succeeded) {
1599     return result;
1600   }
1601 
1602   // Attempts to allocate followed by Full GC that will collect all soft references.
1603   result = satisfy_failed_allocation_helper(word_size,
1604                                             context,
1605                                             true, /* do_gc */
1606                                             true, /* clear_all_soft_refs */
1607                                             true, /* expect_null_mutator_alloc_region */
1608                                             succeeded);
1609 
1610   if (result != NULL || !*succeeded) {
1611     return result;
1612   }
1613 
1614   // Attempts to allocate, no GC
1615   result = satisfy_failed_allocation_helper(word_size,
1616                                             context,
1617                                             false, /* do_gc */
1618                                             false, /* clear_all_soft_refs */
1619                                             true,  /* expect_null_mutator_alloc_region */
1620                                             succeeded);
1621 
1622   if (result != NULL) {
1623     assert(*succeeded, "sanity");
1624     return result;
1625   }
1626 
1627   assert(!collector_policy()->should_clear_all_soft_refs(),
1628          "Flag should have been handled and cleared prior to this point");
1629 
1630   // What else?  We might try synchronous finalization later.  If the total
1631   // space available is large enough for the allocation, then a more
1632   // complete compaction phase than we've tried so far might be
1633   // appropriate.
1634   assert(*succeeded, "sanity");
1635   return NULL;
1636 }
1637 
1638 // Attempting to expand the heap sufficiently
1639 // to support an allocation of the given "word_size".  If
1640 // successful, perform the allocation and return the address of the
1641 // allocated block, or else "NULL".
1642 
1643 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1644   assert_at_safepoint(true /* should_be_vm_thread */);
1645 
1646   _verifier->verify_region_sets_optional();
1647 
1648   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1649   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1650                             word_size * HeapWordSize);
1651 
1652 
1653   if (expand(expand_bytes)) {
1654     _hrm.verify_optional();
1655     _verifier->verify_region_sets_optional();
1656     return attempt_allocation_at_safepoint(word_size,
1657                                            context,
1658                                            false /* expect_null_mutator_alloc_region */);
1659   }
1660   return NULL;
1661 }
1662 
1663 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1664   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1665   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1666                                        HeapRegion::GrainBytes);
1667 
1668   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1669                             expand_bytes, aligned_expand_bytes);
1670 
1671   if (is_maximal_no_gc()) {
1672     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1673     return false;
1674   }
1675 
1676   double expand_heap_start_time_sec = os::elapsedTime();
1677   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1678   assert(regions_to_expand > 0, "Must expand by at least one region");
1679 
1680   uint expanded_by = _hrm.expand_by(regions_to_expand);
1681   if (expand_time_ms != NULL) {
1682     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1683   }
1684 
1685   if (expanded_by > 0) {
1686     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1687     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1688     g1_policy()->record_new_heap_size(num_regions());
1689   } else {
1690     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1691 
1692     // The expansion of the virtual storage space was unsuccessful.
1693     // Let's see if it was because we ran out of swap.
1694     if (G1ExitOnExpansionFailure &&
1695         _hrm.available() >= regions_to_expand) {
1696       // We had head room...
1697       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1698     }
1699   }
1700   return regions_to_expand > 0;
1701 }
1702 
1703 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1704   size_t aligned_shrink_bytes =
1705     ReservedSpace::page_align_size_down(shrink_bytes);
1706   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1707                                          HeapRegion::GrainBytes);
1708   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1709 
1710   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1711   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1712 
1713 
1714   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",
1715                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1716   if (num_regions_removed > 0) {
1717     g1_policy()->record_new_heap_size(num_regions());
1718   } else {
1719     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1720   }
1721 }
1722 
1723 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1724   _verifier->verify_region_sets_optional();
1725 
1726   // We should only reach here at the end of a Full GC which means we
1727   // should not not be holding to any GC alloc regions. The method
1728   // below will make sure of that and do any remaining clean up.
1729   _allocator->abandon_gc_alloc_regions();
1730 
1731   // Instead of tearing down / rebuilding the free lists here, we
1732   // could instead use the remove_all_pending() method on free_list to
1733   // remove only the ones that we need to remove.
1734   tear_down_region_sets(true /* free_list_only */);
1735   shrink_helper(shrink_bytes);
1736   rebuild_region_sets(true /* free_list_only */);
1737 
1738   _hrm.verify_optional();
1739   _verifier->verify_region_sets_optional();
1740 }
1741 
1742 // Public methods.
1743 
1744 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1745   CollectedHeap(),
1746   _g1_policy(policy_),
1747   _collection_set(this),
1748   _dirty_card_queue_set(false),
1749   _is_alive_closure_cm(this),
1750   _is_alive_closure_stw(this),
1751   _ref_processor_cm(NULL),
1752   _ref_processor_stw(NULL),
1753   _bot(NULL),
1754   _cg1r(NULL),
1755   _g1mm(NULL),
1756   _refine_cte_cl(NULL),
1757   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1758   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1759   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1760   _humongous_reclaim_candidates(),
1761   _has_humongous_reclaim_candidates(false),
1762   _archive_allocator(NULL),
1763   _free_regions_coming(false),
1764   _young_list(new YoungList(this)),
1765   _gc_time_stamp(0),
1766   _summary_bytes_used(0),
1767   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1768   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1769   _expand_heap_after_alloc_failure(true),
1770   _old_marking_cycles_started(0),
1771   _old_marking_cycles_completed(0),
1772   _heap_summary_sent(false),
1773   _in_cset_fast_test(),
1774   _dirty_cards_region_list(NULL),
1775   _worker_cset_start_region(NULL),
1776   _worker_cset_start_region_time_stamp(NULL),
1777   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1778   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1779   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1780   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
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   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1790 
1791   // Override the default _filler_array_max_size so that no humongous filler
1792   // objects are created.
1793   _filler_array_max_size = _humongous_object_threshold_in_words;
1794 
1795   uint n_queues = ParallelGCThreads;
1796   _task_queues = new RefToScanQueueSet(n_queues);
1797 
1798   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1799   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1800   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1801 
1802   for (uint i = 0; i < n_queues; i++) {
1803     RefToScanQueue* q = new RefToScanQueue();
1804     q->initialize();
1805     _task_queues->register_queue(i, q);
1806     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1807   }
1808   clear_cset_start_regions();
1809 
1810   // Initialize the G1EvacuationFailureALot counters and flags.
1811   NOT_PRODUCT(reset_evacuation_should_fail();)
1812 
1813   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1814 }
1815 
1816 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1817                                                                  size_t size,
1818                                                                  size_t translation_factor) {
1819   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1820   // Allocate a new reserved space, preferring to use large pages.
1821   ReservedSpace rs(size, preferred_page_size);
1822   G1RegionToSpaceMapper* result  =
1823     G1RegionToSpaceMapper::create_mapper(rs,
1824                                          size,
1825                                          rs.alignment(),
1826                                          HeapRegion::GrainBytes,
1827                                          translation_factor,
1828                                          mtGC);
1829   if (TracePageSizes) {
1830     tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1831                   description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1832   }
1833   return result;
1834 }
1835 
1836 jint G1CollectedHeap::initialize() {
1837   CollectedHeap::pre_initialize();
1838   os::enable_vtime();
1839 
1840   // Necessary to satisfy locking discipline assertions.
1841 
1842   MutexLocker x(Heap_lock);
1843 
1844   // While there are no constraints in the GC code that HeapWordSize
1845   // be any particular value, there are multiple other areas in the
1846   // system which believe this to be true (e.g. oop->object_size in some
1847   // cases incorrectly returns the size in wordSize units rather than
1848   // HeapWordSize).
1849   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1850 
1851   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1852   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1853   size_t heap_alignment = collector_policy()->heap_alignment();
1854 
1855   // Ensure that the sizes are properly aligned.
1856   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1857   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1858   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1859 
1860   _refine_cte_cl = new RefineCardTableEntryClosure();
1861 
1862   jint ecode = JNI_OK;
1863   _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1864   if (_cg1r == NULL) {
1865     return ecode;
1866   }
1867 
1868   // Reserve the maximum.
1869 
1870   // When compressed oops are enabled, the preferred heap base
1871   // is calculated by subtracting the requested size from the
1872   // 32Gb boundary and using the result as the base address for
1873   // heap reservation. If the requested size is not aligned to
1874   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1875   // into the ReservedHeapSpace constructor) then the actual
1876   // base of the reserved heap may end up differing from the
1877   // address that was requested (i.e. the preferred heap base).
1878   // If this happens then we could end up using a non-optimal
1879   // compressed oops mode.
1880 
1881   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1882                                                  heap_alignment);
1883 
1884   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1885 
1886   // Create the barrier set for the entire reserved region.
1887   G1SATBCardTableLoggingModRefBS* bs
1888     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1889   bs->initialize();
1890   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1891   set_barrier_set(bs);
1892 
1893   // Also create a G1 rem set.
1894   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1895 
1896   // Carve out the G1 part of the heap.
1897   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1898   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1899   G1RegionToSpaceMapper* heap_storage =
1900     G1RegionToSpaceMapper::create_mapper(g1_rs,
1901                                          g1_rs.size(),
1902                                          page_size,
1903                                          HeapRegion::GrainBytes,
1904                                          1,
1905                                          mtJavaHeap);
1906   os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1907                        max_byte_size, page_size,
1908                        heap_rs.base(),
1909                        heap_rs.size());
1910   heap_storage->set_mapping_changed_listener(&_listener);
1911 
1912   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1913   G1RegionToSpaceMapper* bot_storage =
1914     create_aux_memory_mapper("Block offset table",
1915                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1916                              G1BlockOffsetTable::heap_map_factor());
1917 
1918   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1919   G1RegionToSpaceMapper* cardtable_storage =
1920     create_aux_memory_mapper("Card table",
1921                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1922                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1923 
1924   G1RegionToSpaceMapper* card_counts_storage =
1925     create_aux_memory_mapper("Card counts table",
1926                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1927                              G1CardCounts::heap_map_factor());
1928 
1929   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1930   G1RegionToSpaceMapper* prev_bitmap_storage =
1931     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1932   G1RegionToSpaceMapper* next_bitmap_storage =
1933     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1934 
1935   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1936   g1_barrier_set()->initialize(cardtable_storage);
1937    // Do later initialization work for concurrent refinement.
1938   _cg1r->init(card_counts_storage);
1939 
1940   // 6843694 - ensure that the maximum region index can fit
1941   // in the remembered set structures.
1942   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1943   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1944 
1945   G1RemSet::initialize(max_regions());
1946 
1947   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1948   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1949   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1950             "too many cards per region");
1951 
1952   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1953 
1954   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1955 
1956   {
1957     HeapWord* start = _hrm.reserved().start();
1958     HeapWord* end = _hrm.reserved().end();
1959     size_t granularity = HeapRegion::GrainBytes;
1960 
1961     _in_cset_fast_test.initialize(start, end, granularity);
1962     _humongous_reclaim_candidates.initialize(start, end, granularity);
1963   }
1964 
1965   // Create the G1ConcurrentMark data structure and thread.
1966   // (Must do this late, so that "max_regions" is defined.)
1967   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1968   if (_cm == NULL || !_cm->completed_initialization()) {
1969     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1970     return JNI_ENOMEM;
1971   }
1972   _cmThread = _cm->cmThread();
1973 
1974   // Now expand into the initial heap size.
1975   if (!expand(init_byte_size)) {
1976     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1977     return JNI_ENOMEM;
1978   }
1979 
1980   // Perform any initialization actions delegated to the policy.
1981   g1_policy()->init();
1982 
1983   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1984                                                SATB_Q_FL_lock,
1985                                                G1SATBProcessCompletedThreshold,
1986                                                Shared_SATB_Q_lock);
1987 
1988   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1989                                                 DirtyCardQ_CBL_mon,
1990                                                 DirtyCardQ_FL_lock,
1991                                                 (int)concurrent_g1_refine()->yellow_zone(),
1992                                                 (int)concurrent_g1_refine()->red_zone(),
1993                                                 Shared_DirtyCardQ_lock,
1994                                                 NULL,  // fl_owner
1995                                                 true); // init_free_ids
1996 
1997   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1998                                     DirtyCardQ_CBL_mon,
1999                                     DirtyCardQ_FL_lock,
2000                                     -1, // never trigger processing
2001                                     -1, // no limit on length
2002                                     Shared_DirtyCardQ_lock,
2003                                     &JavaThread::dirty_card_queue_set());
2004 
2005   // Here we allocate the dummy HeapRegion that is required by the
2006   // G1AllocRegion class.
2007   HeapRegion* dummy_region = _hrm.get_dummy_region();
2008 
2009   // We'll re-use the same region whether the alloc region will
2010   // require BOT updates or not and, if it doesn't, then a non-young
2011   // region will complain that it cannot support allocations without
2012   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2013   dummy_region->set_eden();
2014   // Make sure it's full.
2015   dummy_region->set_top(dummy_region->end());
2016   G1AllocRegion::setup(this, dummy_region);
2017 
2018   _allocator->init_mutator_alloc_region();
2019 
2020   // Do create of the monitoring and management support so that
2021   // values in the heap have been properly initialized.
2022   _g1mm = new G1MonitoringSupport(this);
2023 
2024   G1StringDedup::initialize();
2025 
2026   _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2027   for (uint i = 0; i < ParallelGCThreads; i++) {
2028     new (&_preserved_objs[i]) OopAndMarkOopStack();
2029   }
2030 
2031   return JNI_OK;
2032 }
2033 
2034 void G1CollectedHeap::stop() {
2035   // Stop all concurrent threads. We do this to make sure these threads
2036   // do not continue to execute and access resources (e.g. logging)
2037   // that are destroyed during shutdown.
2038   _cg1r->stop();
2039   _cmThread->stop();
2040   if (G1StringDedup::is_enabled()) {
2041     G1StringDedup::stop();
2042   }
2043 }
2044 
2045 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2046   return HeapRegion::max_region_size();
2047 }
2048 
2049 void G1CollectedHeap::post_initialize() {
2050   CollectedHeap::post_initialize();
2051   ref_processing_init();
2052 }
2053 
2054 void G1CollectedHeap::ref_processing_init() {
2055   // Reference processing in G1 currently works as follows:
2056   //
2057   // * There are two reference processor instances. One is
2058   //   used to record and process discovered references
2059   //   during concurrent marking; the other is used to
2060   //   record and process references during STW pauses
2061   //   (both full and incremental).
2062   // * Both ref processors need to 'span' the entire heap as
2063   //   the regions in the collection set may be dotted around.
2064   //
2065   // * For the concurrent marking ref processor:
2066   //   * Reference discovery is enabled at initial marking.
2067   //   * Reference discovery is disabled and the discovered
2068   //     references processed etc during remarking.
2069   //   * Reference discovery is MT (see below).
2070   //   * Reference discovery requires a barrier (see below).
2071   //   * Reference processing may or may not be MT
2072   //     (depending on the value of ParallelRefProcEnabled
2073   //     and ParallelGCThreads).
2074   //   * A full GC disables reference discovery by the CM
2075   //     ref processor and abandons any entries on it's
2076   //     discovered lists.
2077   //
2078   // * For the STW processor:
2079   //   * Non MT discovery is enabled at the start of a full GC.
2080   //   * Processing and enqueueing during a full GC is non-MT.
2081   //   * During a full GC, references are processed after marking.
2082   //
2083   //   * Discovery (may or may not be MT) is enabled at the start
2084   //     of an incremental evacuation pause.
2085   //   * References are processed near the end of a STW evacuation pause.
2086   //   * For both types of GC:
2087   //     * Discovery is atomic - i.e. not concurrent.
2088   //     * Reference discovery will not need a barrier.
2089 
2090   MemRegion mr = reserved_region();
2091 
2092   // Concurrent Mark ref processor
2093   _ref_processor_cm =
2094     new ReferenceProcessor(mr,    // span
2095                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2096                                 // mt processing
2097                            ParallelGCThreads,
2098                                 // degree of mt processing
2099                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2100                                 // mt discovery
2101                            MAX2(ParallelGCThreads, ConcGCThreads),
2102                                 // degree of mt discovery
2103                            false,
2104                                 // Reference discovery is not atomic
2105                            &_is_alive_closure_cm);
2106                                 // is alive closure
2107                                 // (for efficiency/performance)
2108 
2109   // STW ref processor
2110   _ref_processor_stw =
2111     new ReferenceProcessor(mr,    // span
2112                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2113                                 // mt processing
2114                            ParallelGCThreads,
2115                                 // degree of mt processing
2116                            (ParallelGCThreads > 1),
2117                                 // mt discovery
2118                            ParallelGCThreads,
2119                                 // degree of mt discovery
2120                            true,
2121                                 // Reference discovery is atomic
2122                            &_is_alive_closure_stw);
2123                                 // is alive closure
2124                                 // (for efficiency/performance)
2125 }
2126 
2127 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2128   return g1_policy();
2129 }
2130 
2131 size_t G1CollectedHeap::capacity() const {
2132   return _hrm.length() * HeapRegion::GrainBytes;
2133 }
2134 
2135 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2136   hr->reset_gc_time_stamp();
2137 }
2138 
2139 #ifndef PRODUCT
2140 
2141 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2142 private:
2143   unsigned _gc_time_stamp;
2144   bool _failures;
2145 
2146 public:
2147   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2148     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2149 
2150   virtual bool doHeapRegion(HeapRegion* hr) {
2151     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2152     if (_gc_time_stamp != region_gc_time_stamp) {
2153       log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2154                             region_gc_time_stamp, _gc_time_stamp);
2155       _failures = true;
2156     }
2157     return false;
2158   }
2159 
2160   bool failures() { return _failures; }
2161 };
2162 
2163 void G1CollectedHeap::check_gc_time_stamps() {
2164   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2165   heap_region_iterate(&cl);
2166   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2167 }
2168 #endif // PRODUCT
2169 
2170 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2171   _cg1r->hot_card_cache()->drain(cl, worker_i);
2172 }
2173 
2174 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2175   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2176   size_t n_completed_buffers = 0;
2177   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2178     n_completed_buffers++;
2179   }
2180   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2181   dcqs.clear_n_completed_buffers();
2182   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2183 }
2184 
2185 // Computes the sum of the storage used by the various regions.
2186 size_t G1CollectedHeap::used() const {
2187   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2188   if (_archive_allocator != NULL) {
2189     result += _archive_allocator->used();
2190   }
2191   return result;
2192 }
2193 
2194 size_t G1CollectedHeap::used_unlocked() const {
2195   return _summary_bytes_used;
2196 }
2197 
2198 class SumUsedClosure: public HeapRegionClosure {
2199   size_t _used;
2200 public:
2201   SumUsedClosure() : _used(0) {}
2202   bool doHeapRegion(HeapRegion* r) {
2203     _used += r->used();
2204     return false;
2205   }
2206   size_t result() { return _used; }
2207 };
2208 
2209 size_t G1CollectedHeap::recalculate_used() const {
2210   double recalculate_used_start = os::elapsedTime();
2211 
2212   SumUsedClosure blk;
2213   heap_region_iterate(&blk);
2214 
2215   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2216   return blk.result();
2217 }
2218 
2219 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2220   switch (cause) {
2221     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2222     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2223     case GCCause::_update_allocation_context_stats_inc: return true;
2224     case GCCause::_wb_conc_mark:                        return true;
2225     default :                                           return false;
2226   }
2227 }
2228 
2229 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2230   switch (cause) {
2231     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2232     case GCCause::_g1_humongous_allocation: return true;
2233     default:                                return is_user_requested_concurrent_full_gc(cause);
2234   }
2235 }
2236 
2237 #ifndef PRODUCT
2238 void G1CollectedHeap::allocate_dummy_regions() {
2239   // Let's fill up most of the region
2240   size_t word_size = HeapRegion::GrainWords - 1024;
2241   // And as a result the region we'll allocate will be humongous.
2242   guarantee(is_humongous(word_size), "sanity");
2243 
2244   // _filler_array_max_size is set to humongous object threshold
2245   // but temporarily change it to use CollectedHeap::fill_with_object().
2246   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2247 
2248   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2249     // Let's use the existing mechanism for the allocation
2250     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2251                                                  AllocationContext::system());
2252     if (dummy_obj != NULL) {
2253       MemRegion mr(dummy_obj, word_size);
2254       CollectedHeap::fill_with_object(mr);
2255     } else {
2256       // If we can't allocate once, we probably cannot allocate
2257       // again. Let's get out of the loop.
2258       break;
2259     }
2260   }
2261 }
2262 #endif // !PRODUCT
2263 
2264 void G1CollectedHeap::increment_old_marking_cycles_started() {
2265   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2266          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2267          "Wrong marking cycle count (started: %d, completed: %d)",
2268          _old_marking_cycles_started, _old_marking_cycles_completed);
2269 
2270   _old_marking_cycles_started++;
2271 }
2272 
2273 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2274   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2275 
2276   // We assume that if concurrent == true, then the caller is a
2277   // concurrent thread that was joined the Suspendible Thread
2278   // Set. If there's ever a cheap way to check this, we should add an
2279   // assert here.
2280 
2281   // Given that this method is called at the end of a Full GC or of a
2282   // concurrent cycle, and those can be nested (i.e., a Full GC can
2283   // interrupt a concurrent cycle), the number of full collections
2284   // completed should be either one (in the case where there was no
2285   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2286   // behind the number of full collections started.
2287 
2288   // This is the case for the inner caller, i.e. a Full GC.
2289   assert(concurrent ||
2290          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2291          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2292          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2293          "is inconsistent with _old_marking_cycles_completed = %u",
2294          _old_marking_cycles_started, _old_marking_cycles_completed);
2295 
2296   // This is the case for the outer caller, i.e. the concurrent cycle.
2297   assert(!concurrent ||
2298          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2299          "for outer caller (concurrent cycle): "
2300          "_old_marking_cycles_started = %u "
2301          "is inconsistent with _old_marking_cycles_completed = %u",
2302          _old_marking_cycles_started, _old_marking_cycles_completed);
2303 
2304   _old_marking_cycles_completed += 1;
2305 
2306   // We need to clear the "in_progress" flag in the CM thread before
2307   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2308   // is set) so that if a waiter requests another System.gc() it doesn't
2309   // incorrectly see that a marking cycle is still in progress.
2310   if (concurrent) {
2311     _cmThread->set_idle();
2312   }
2313 
2314   // This notify_all() will ensure that a thread that called
2315   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2316   // and it's waiting for a full GC to finish will be woken up. It is
2317   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2318   FullGCCount_lock->notify_all();
2319 }
2320 
2321 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2322   GCIdMarkAndRestore conc_gc_id_mark;
2323   collector_state()->set_concurrent_cycle_started(true);
2324   _gc_timer_cm->register_gc_start(start_time);
2325 
2326   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2327   trace_heap_before_gc(_gc_tracer_cm);
2328   _cmThread->set_gc_id(GCId::current());
2329 }
2330 
2331 void G1CollectedHeap::register_concurrent_cycle_end() {
2332   if (collector_state()->concurrent_cycle_started()) {
2333     GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2334     if (_cm->has_aborted()) {
2335       _gc_tracer_cm->report_concurrent_mode_failure();
2336 
2337       // ConcurrentGCTimer will be ended as well.
2338       _cm->register_concurrent_gc_end_and_stop_timer();
2339     } else {
2340       _gc_timer_cm->register_gc_end();
2341     }
2342 
2343     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2344 
2345     // Clear state variables to prepare for the next concurrent cycle.
2346     collector_state()->set_concurrent_cycle_started(false);
2347     _heap_summary_sent = false;
2348   }
2349 }
2350 
2351 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2352   if (collector_state()->concurrent_cycle_started()) {
2353     // This function can be called when:
2354     //  the cleanup pause is run
2355     //  the concurrent cycle is aborted before the cleanup pause.
2356     //  the concurrent cycle is aborted after the cleanup pause,
2357     //   but before the concurrent cycle end has been registered.
2358     // Make sure that we only send the heap information once.
2359     if (!_heap_summary_sent) {
2360       GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2361       trace_heap_after_gc(_gc_tracer_cm);
2362       _heap_summary_sent = true;
2363     }
2364   }
2365 }
2366 
2367 void G1CollectedHeap::collect(GCCause::Cause cause) {
2368   assert_heap_not_locked();
2369 
2370   uint gc_count_before;
2371   uint old_marking_count_before;
2372   uint full_gc_count_before;
2373   bool retry_gc;
2374 
2375   do {
2376     retry_gc = false;
2377 
2378     {
2379       MutexLocker ml(Heap_lock);
2380 
2381       // Read the GC count while holding the Heap_lock
2382       gc_count_before = total_collections();
2383       full_gc_count_before = total_full_collections();
2384       old_marking_count_before = _old_marking_cycles_started;
2385     }
2386 
2387     if (should_do_concurrent_full_gc(cause)) {
2388       // Schedule an initial-mark evacuation pause that will start a
2389       // concurrent cycle. We're setting word_size to 0 which means that
2390       // we are not requesting a post-GC allocation.
2391       VM_G1IncCollectionPause op(gc_count_before,
2392                                  0,     /* word_size */
2393                                  true,  /* should_initiate_conc_mark */
2394                                  g1_policy()->max_pause_time_ms(),
2395                                  cause);
2396       op.set_allocation_context(AllocationContext::current());
2397 
2398       VMThread::execute(&op);
2399       if (!op.pause_succeeded()) {
2400         if (old_marking_count_before == _old_marking_cycles_started) {
2401           retry_gc = op.should_retry_gc();
2402         } else {
2403           // A Full GC happened while we were trying to schedule the
2404           // initial-mark GC. No point in starting a new cycle given
2405           // that the whole heap was collected anyway.
2406         }
2407 
2408         if (retry_gc) {
2409           if (GCLocker::is_active_and_needs_gc()) {
2410             GCLocker::stall_until_clear();
2411           }
2412         }
2413       }
2414     } else {
2415       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2416           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2417 
2418         // Schedule a standard evacuation pause. We're setting word_size
2419         // to 0 which means that we are not requesting a post-GC allocation.
2420         VM_G1IncCollectionPause op(gc_count_before,
2421                                    0,     /* word_size */
2422                                    false, /* should_initiate_conc_mark */
2423                                    g1_policy()->max_pause_time_ms(),
2424                                    cause);
2425         VMThread::execute(&op);
2426       } else {
2427         // Schedule a Full GC.
2428         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2429         VMThread::execute(&op);
2430       }
2431     }
2432   } while (retry_gc);
2433 }
2434 
2435 bool G1CollectedHeap::is_in(const void* p) const {
2436   if (_hrm.reserved().contains(p)) {
2437     // Given that we know that p is in the reserved space,
2438     // heap_region_containing() should successfully
2439     // return the containing region.
2440     HeapRegion* hr = heap_region_containing(p);
2441     return hr->is_in(p);
2442   } else {
2443     return false;
2444   }
2445 }
2446 
2447 #ifdef ASSERT
2448 bool G1CollectedHeap::is_in_exact(const void* p) const {
2449   bool contains = reserved_region().contains(p);
2450   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2451   if (contains && available) {
2452     return true;
2453   } else {
2454     return false;
2455   }
2456 }
2457 #endif
2458 
2459 bool G1CollectedHeap::obj_in_cs(oop obj) {
2460   HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2461   return r != NULL && r->in_collection_set();
2462 }
2463 
2464 // Iteration functions.
2465 
2466 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2467 
2468 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2469   ExtendedOopClosure* _cl;
2470 public:
2471   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2472   bool doHeapRegion(HeapRegion* r) {
2473     if (!r->is_continues_humongous()) {
2474       r->oop_iterate(_cl);
2475     }
2476     return false;
2477   }
2478 };
2479 
2480 // Iterates an ObjectClosure over all objects within a HeapRegion.
2481 
2482 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2483   ObjectClosure* _cl;
2484 public:
2485   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2486   bool doHeapRegion(HeapRegion* r) {
2487     if (!r->is_continues_humongous()) {
2488       r->object_iterate(_cl);
2489     }
2490     return false;
2491   }
2492 };
2493 
2494 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2495   IterateObjectClosureRegionClosure blk(cl);
2496   heap_region_iterate(&blk);
2497 }
2498 
2499 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2500   _hrm.iterate(cl);
2501 }
2502 
2503 void
2504 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2505                                          uint worker_id,
2506                                          HeapRegionClaimer *hrclaimer,
2507                                          bool concurrent) const {
2508   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2509 }
2510 
2511 // Clear the cached CSet starting regions and (more importantly)
2512 // the time stamps. Called when we reset the GC time stamp.
2513 void G1CollectedHeap::clear_cset_start_regions() {
2514   assert(_worker_cset_start_region != NULL, "sanity");
2515   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2516 
2517   for (uint i = 0; i < ParallelGCThreads; i++) {
2518     _worker_cset_start_region[i] = NULL;
2519     _worker_cset_start_region_time_stamp[i] = 0;
2520   }
2521 }
2522 
2523 // Given the id of a worker, obtain or calculate a suitable
2524 // starting region for iterating over the current collection set.
2525 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2526   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2527 
2528   HeapRegion* result = NULL;
2529   unsigned gc_time_stamp = get_gc_time_stamp();
2530 
2531   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2532     // Cached starting region for current worker was set
2533     // during the current pause - so it's valid.
2534     // Note: the cached starting heap region may be NULL
2535     // (when the collection set is empty).
2536     result = _worker_cset_start_region[worker_i];
2537     assert(result == NULL || result->in_collection_set(), "sanity");
2538     return result;
2539   }
2540 
2541   // The cached entry was not valid so let's calculate
2542   // a suitable starting heap region for this worker.
2543 
2544   // We want the parallel threads to start their collection
2545   // set iteration at different collection set regions to
2546   // avoid contention.
2547   // If we have:
2548   //          n collection set regions
2549   //          p threads
2550   // Then thread t will start at region floor ((t * n) / p)
2551 
2552   result = collection_set()->head();
2553   uint cs_size = collection_set()->region_length();
2554   uint active_workers = workers()->active_workers();
2555 
2556   uint end_ind   = (cs_size * worker_i) / active_workers;
2557   uint start_ind = 0;
2558 
2559   if (worker_i > 0 &&
2560       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2561     // Previous workers starting region is valid
2562     // so let's iterate from there
2563     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2564     OrderAccess::loadload();
2565     result = _worker_cset_start_region[worker_i - 1];
2566   }
2567 
2568   for (uint i = start_ind; i < end_ind; i++) {
2569     result = result->next_in_collection_set();
2570   }
2571 
2572   // Note: the calculated starting heap region may be NULL
2573   // (when the collection set is empty).
2574   assert(result == NULL || result->in_collection_set(), "sanity");
2575   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2576          "should be updated only once per pause");
2577   _worker_cset_start_region[worker_i] = result;
2578   OrderAccess::storestore();
2579   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2580   return result;
2581 }
2582 
2583 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2584   HeapRegion* r = collection_set()->head();
2585   while (r != NULL) {
2586     HeapRegion* next = r->next_in_collection_set();
2587     if (cl->doHeapRegion(r)) {
2588       cl->incomplete();
2589       return;
2590     }
2591     r = next;
2592   }
2593 }
2594 
2595 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2596                                                   HeapRegionClosure *cl) {
2597   if (r == NULL) {
2598     // The CSet is empty so there's nothing to do.
2599     return;
2600   }
2601 
2602   assert(r->in_collection_set(),
2603          "Start region must be a member of the collection set.");
2604   HeapRegion* cur = r;
2605   while (cur != NULL) {
2606     HeapRegion* next = cur->next_in_collection_set();
2607     if (cl->doHeapRegion(cur) && false) {
2608       cl->incomplete();
2609       return;
2610     }
2611     cur = next;
2612   }
2613   cur = collection_set()->head();
2614   while (cur != r) {
2615     HeapRegion* next = cur->next_in_collection_set();
2616     if (cl->doHeapRegion(cur) && false) {
2617       cl->incomplete();
2618       return;
2619     }
2620     cur = next;
2621   }
2622 }
2623 
2624 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2625   HeapRegion* result = _hrm.next_region_in_heap(from);
2626   while (result != NULL && result->is_pinned()) {
2627     result = _hrm.next_region_in_heap(result);
2628   }
2629   return result;
2630 }
2631 
2632 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2633   HeapRegion* hr = heap_region_containing(addr);
2634   return hr->block_start(addr);
2635 }
2636 
2637 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2638   HeapRegion* hr = heap_region_containing(addr);
2639   return hr->block_size(addr);
2640 }
2641 
2642 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2643   HeapRegion* hr = heap_region_containing(addr);
2644   return hr->block_is_obj(addr);
2645 }
2646 
2647 bool G1CollectedHeap::supports_tlab_allocation() const {
2648   return true;
2649 }
2650 
2651 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2652   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2653 }
2654 
2655 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2656   return young_list()->eden_used_bytes();
2657 }
2658 
2659 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2660 // must be equal to the humongous object limit.
2661 size_t G1CollectedHeap::max_tlab_size() const {
2662   return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2663 }
2664 
2665 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2666   AllocationContext_t context = AllocationContext::current();
2667   return _allocator->unsafe_max_tlab_alloc(context);
2668 }
2669 
2670 size_t G1CollectedHeap::max_capacity() const {
2671   return _hrm.reserved().byte_size();
2672 }
2673 
2674 jlong G1CollectedHeap::millis_since_last_gc() {
2675   // assert(false, "NYI");
2676   return 0;
2677 }
2678 
2679 void G1CollectedHeap::prepare_for_verify() {
2680   _verifier->prepare_for_verify();
2681 }
2682 
2683 void G1CollectedHeap::verify(VerifyOption vo) {
2684   _verifier->verify(vo);
2685 }
2686 
2687 class PrintRegionClosure: public HeapRegionClosure {
2688   outputStream* _st;
2689 public:
2690   PrintRegionClosure(outputStream* st) : _st(st) {}
2691   bool doHeapRegion(HeapRegion* r) {
2692     r->print_on(_st);
2693     return false;
2694   }
2695 };
2696 
2697 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2698                                        const HeapRegion* hr,
2699                                        const VerifyOption vo) const {
2700   switch (vo) {
2701   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2702   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2703   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
2704   default:                            ShouldNotReachHere();
2705   }
2706   return false; // keep some compilers happy
2707 }
2708 
2709 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2710                                        const VerifyOption vo) const {
2711   switch (vo) {
2712   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2713   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2714   case VerifyOption_G1UseMarkWord: {
2715     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2716     return !obj->is_gc_marked() && !hr->is_archive();
2717   }
2718   default:                            ShouldNotReachHere();
2719   }
2720   return false; // keep some compilers happy
2721 }
2722 
2723 void G1CollectedHeap::print_heap_regions() const {
2724   LogHandle(gc, heap, region) log;
2725   if (log.is_trace()) {
2726     ResourceMark rm;
2727     print_regions_on(log.trace_stream());
2728   }
2729 }
2730 
2731 void G1CollectedHeap::print_on(outputStream* st) const {
2732   st->print(" %-20s", "garbage-first heap");
2733   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2734             capacity()/K, used_unlocked()/K);
2735   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2736             p2i(_hrm.reserved().start()),
2737             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2738             p2i(_hrm.reserved().end()));
2739   st->cr();
2740   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2741   uint young_regions = _young_list->length();
2742   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2743             (size_t) young_regions * HeapRegion::GrainBytes / K);
2744   uint survivor_regions = _young_list->survivor_length();
2745   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2746             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2747   st->cr();
2748   MetaspaceAux::print_on(st);
2749 }
2750 
2751 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2752   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2753                "HS=humongous(starts), HC=humongous(continues), "
2754                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2755                "AC=allocation context, "
2756                "TAMS=top-at-mark-start (previous, next)");
2757   PrintRegionClosure blk(st);
2758   heap_region_iterate(&blk);
2759 }
2760 
2761 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2762   print_on(st);
2763 
2764   // Print the per-region information.
2765   print_regions_on(st);
2766 }
2767 
2768 void G1CollectedHeap::print_on_error(outputStream* st) const {
2769   this->CollectedHeap::print_on_error(st);
2770 
2771   if (_cm != NULL) {
2772     st->cr();
2773     _cm->print_on_error(st);
2774   }
2775 }
2776 
2777 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2778   workers()->print_worker_threads_on(st);
2779   _cmThread->print_on(st);
2780   st->cr();
2781   _cm->print_worker_threads_on(st);
2782   _cg1r->print_worker_threads_on(st);
2783   if (G1StringDedup::is_enabled()) {
2784     G1StringDedup::print_worker_threads_on(st);
2785   }
2786 }
2787 
2788 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2789   workers()->threads_do(tc);
2790   tc->do_thread(_cmThread);
2791   _cg1r->threads_do(tc);
2792   if (G1StringDedup::is_enabled()) {
2793     G1StringDedup::threads_do(tc);
2794   }
2795 }
2796 
2797 void G1CollectedHeap::print_tracing_info() const {
2798   g1_rem_set()->print_summary_info();
2799   concurrent_mark()->print_summary_info();
2800   g1_policy()->print_yg_surv_rate_info();
2801 }
2802 
2803 #ifndef PRODUCT
2804 // Helpful for debugging RSet issues.
2805 
2806 class PrintRSetsClosure : public HeapRegionClosure {
2807 private:
2808   const char* _msg;
2809   size_t _occupied_sum;
2810 
2811 public:
2812   bool doHeapRegion(HeapRegion* r) {
2813     HeapRegionRemSet* hrrs = r->rem_set();
2814     size_t occupied = hrrs->occupied();
2815     _occupied_sum += occupied;
2816 
2817     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2818     if (occupied == 0) {
2819       tty->print_cr("  RSet is empty");
2820     } else {
2821       hrrs->print();
2822     }
2823     tty->print_cr("----------");
2824     return false;
2825   }
2826 
2827   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2828     tty->cr();
2829     tty->print_cr("========================================");
2830     tty->print_cr("%s", msg);
2831     tty->cr();
2832   }
2833 
2834   ~PrintRSetsClosure() {
2835     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2836     tty->print_cr("========================================");
2837     tty->cr();
2838   }
2839 };
2840 
2841 void G1CollectedHeap::print_cset_rsets() {
2842   PrintRSetsClosure cl("Printing CSet RSets");
2843   collection_set_iterate(&cl);
2844 }
2845 
2846 void G1CollectedHeap::print_all_rsets() {
2847   PrintRSetsClosure cl("Printing All RSets");;
2848   heap_region_iterate(&cl);
2849 }
2850 #endif // PRODUCT
2851 
2852 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2853   YoungList* young_list = heap()->young_list();
2854 
2855   size_t eden_used_bytes = young_list->eden_used_bytes();
2856   size_t survivor_used_bytes = young_list->survivor_used_bytes();
2857 
2858   size_t eden_capacity_bytes =
2859     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2860 
2861   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2862   return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes, num_regions());
2863 }
2864 
2865 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2866   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2867                        stats->unused(), stats->used(), stats->region_end_waste(),
2868                        stats->regions_filled(), stats->direct_allocated(),
2869                        stats->failure_used(), stats->failure_waste());
2870 }
2871 
2872 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2873   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2874   gc_tracer->report_gc_heap_summary(when, heap_summary);
2875 
2876   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2877   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2878 }
2879 
2880 
2881 G1CollectedHeap* G1CollectedHeap::heap() {
2882   CollectedHeap* heap = Universe::heap();
2883   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2884   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2885   return (G1CollectedHeap*)heap;
2886 }
2887 
2888 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2889   // always_do_update_barrier = false;
2890   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2891   // Fill TLAB's and such
2892   accumulate_statistics_all_tlabs();
2893   ensure_parsability(true);
2894 
2895   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2896 }
2897 
2898 void G1CollectedHeap::gc_epilogue(bool full) {
2899   // we are at the end of the GC. Total collections has already been increased.
2900   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2901 
2902   // FIXME: what is this about?
2903   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2904   // is set.
2905 #if defined(COMPILER2) || INCLUDE_JVMCI
2906   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2907 #endif
2908   // always_do_update_barrier = true;
2909 
2910   resize_all_tlabs();
2911   allocation_context_stats().update(full);
2912 
2913   // We have just completed a GC. Update the soft reference
2914   // policy with the new heap occupancy
2915   Universe::update_heap_info_at_gc();
2916 }
2917 
2918 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2919                                                uint gc_count_before,
2920                                                bool* succeeded,
2921                                                GCCause::Cause gc_cause) {
2922   assert_heap_not_locked_and_not_at_safepoint();
2923   VM_G1IncCollectionPause op(gc_count_before,
2924                              word_size,
2925                              false, /* should_initiate_conc_mark */
2926                              g1_policy()->max_pause_time_ms(),
2927                              gc_cause);
2928 
2929   op.set_allocation_context(AllocationContext::current());
2930   VMThread::execute(&op);
2931 
2932   HeapWord* result = op.result();
2933   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2934   assert(result == NULL || ret_succeeded,
2935          "the result should be NULL if the VM did not succeed");
2936   *succeeded = ret_succeeded;
2937 
2938   assert_heap_not_locked();
2939   return result;
2940 }
2941 
2942 void
2943 G1CollectedHeap::doConcurrentMark() {
2944   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2945   if (!_cmThread->in_progress()) {
2946     _cmThread->set_started();
2947     CGC_lock->notify();
2948   }
2949 }
2950 
2951 size_t G1CollectedHeap::pending_card_num() {
2952   size_t extra_cards = 0;
2953   JavaThread *curr = Threads::first();
2954   while (curr != NULL) {
2955     DirtyCardQueue& dcq = curr->dirty_card_queue();
2956     extra_cards += dcq.size();
2957     curr = curr->next();
2958   }
2959   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2960   size_t buffer_size = dcqs.buffer_size();
2961   size_t buffer_num = dcqs.completed_buffers_num();
2962 
2963   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2964   // in bytes - not the number of 'entries'. We need to convert
2965   // into a number of cards.
2966   return (buffer_size * buffer_num + extra_cards) / oopSize;
2967 }
2968 
2969 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2970  private:
2971   size_t _total_humongous;
2972   size_t _candidate_humongous;
2973 
2974   DirtyCardQueue _dcq;
2975 
2976   // We don't nominate objects with many remembered set entries, on
2977   // the assumption that such objects are likely still live.
2978   bool is_remset_small(HeapRegion* region) const {
2979     HeapRegionRemSet* const rset = region->rem_set();
2980     return G1EagerReclaimHumongousObjectsWithStaleRefs
2981       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2982       : rset->is_empty();
2983   }
2984 
2985   bool is_typeArray_region(HeapRegion* region) const {
2986     return oop(region->bottom())->is_typeArray();
2987   }
2988 
2989   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2990     assert(region->is_starts_humongous(), "Must start a humongous object");
2991 
2992     // Candidate selection must satisfy the following constraints
2993     // while concurrent marking is in progress:
2994     //
2995     // * In order to maintain SATB invariants, an object must not be
2996     // reclaimed if it was allocated before the start of marking and
2997     // has not had its references scanned.  Such an object must have
2998     // its references (including type metadata) scanned to ensure no
2999     // live objects are missed by the marking process.  Objects
3000     // allocated after the start of concurrent marking don't need to
3001     // be scanned.
3002     //
3003     // * An object must not be reclaimed if it is on the concurrent
3004     // mark stack.  Objects allocated after the start of concurrent
3005     // marking are never pushed on the mark stack.
3006     //
3007     // Nominating only objects allocated after the start of concurrent
3008     // marking is sufficient to meet both constraints.  This may miss
3009     // some objects that satisfy the constraints, but the marking data
3010     // structures don't support efficiently performing the needed
3011     // additional tests or scrubbing of the mark stack.
3012     //
3013     // However, we presently only nominate is_typeArray() objects.
3014     // A humongous object containing references induces remembered
3015     // set entries on other regions.  In order to reclaim such an
3016     // object, those remembered sets would need to be cleaned up.
3017     //
3018     // We also treat is_typeArray() objects specially, allowing them
3019     // to be reclaimed even if allocated before the start of
3020     // concurrent mark.  For this we rely on mark stack insertion to
3021     // exclude is_typeArray() objects, preventing reclaiming an object
3022     // that is in the mark stack.  We also rely on the metadata for
3023     // such objects to be built-in and so ensured to be kept live.
3024     // Frequent allocation and drop of large binary blobs is an
3025     // important use case for eager reclaim, and this special handling
3026     // may reduce needed headroom.
3027 
3028     return is_typeArray_region(region) && is_remset_small(region);
3029   }
3030 
3031  public:
3032   RegisterHumongousWithInCSetFastTestClosure()
3033   : _total_humongous(0),
3034     _candidate_humongous(0),
3035     _dcq(&JavaThread::dirty_card_queue_set()) {
3036   }
3037 
3038   virtual bool doHeapRegion(HeapRegion* r) {
3039     if (!r->is_starts_humongous()) {
3040       return false;
3041     }
3042     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3043 
3044     bool is_candidate = humongous_region_is_candidate(g1h, r);
3045     uint rindex = r->hrm_index();
3046     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3047     if (is_candidate) {
3048       _candidate_humongous++;
3049       g1h->register_humongous_region_with_cset(rindex);
3050       // Is_candidate already filters out humongous object with large remembered sets.
3051       // If we have a humongous object with a few remembered sets, we simply flush these
3052       // remembered set entries into the DCQS. That will result in automatic
3053       // re-evaluation of their remembered set entries during the following evacuation
3054       // phase.
3055       if (!r->rem_set()->is_empty()) {
3056         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3057                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3058         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3059         HeapRegionRemSetIterator hrrs(r->rem_set());
3060         size_t card_index;
3061         while (hrrs.has_next(card_index)) {
3062           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3063           // The remembered set might contain references to already freed
3064           // regions. Filter out such entries to avoid failing card table
3065           // verification.
3066           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3067             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3068               *card_ptr = CardTableModRefBS::dirty_card_val();
3069               _dcq.enqueue(card_ptr);
3070             }
3071           }
3072         }
3073         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3074                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3075                hrrs.n_yielded(), r->rem_set()->occupied());
3076         r->rem_set()->clear_locked();
3077       }
3078       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3079     }
3080     _total_humongous++;
3081 
3082     return false;
3083   }
3084 
3085   size_t total_humongous() const { return _total_humongous; }
3086   size_t candidate_humongous() const { return _candidate_humongous; }
3087 
3088   void flush_rem_set_entries() { _dcq.flush(); }
3089 };
3090 
3091 void G1CollectedHeap::register_humongous_regions_with_cset() {
3092   if (!G1EagerReclaimHumongousObjects) {
3093     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3094     return;
3095   }
3096   double time = os::elapsed_counter();
3097 
3098   // Collect reclaim candidate information and register candidates with cset.
3099   RegisterHumongousWithInCSetFastTestClosure cl;
3100   heap_region_iterate(&cl);
3101 
3102   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3103   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3104                                                                   cl.total_humongous(),
3105                                                                   cl.candidate_humongous());
3106   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3107 
3108   // Finally flush all remembered set entries to re-check into the global DCQS.
3109   cl.flush_rem_set_entries();
3110 }
3111 
3112 class VerifyRegionRemSetClosure : public HeapRegionClosure {
3113   public:
3114     bool doHeapRegion(HeapRegion* hr) {
3115       if (!hr->is_archive() && !hr->is_continues_humongous()) {
3116         hr->verify_rem_set();
3117       }
3118       return false;
3119     }
3120 };
3121 
3122 #ifdef ASSERT
3123 class VerifyCSetClosure: public HeapRegionClosure {
3124 public:
3125   bool doHeapRegion(HeapRegion* hr) {
3126     // Here we check that the CSet region's RSet is ready for parallel
3127     // iteration. The fields that we'll verify are only manipulated
3128     // when the region is part of a CSet and is collected. Afterwards,
3129     // we reset these fields when we clear the region's RSet (when the
3130     // region is freed) so they are ready when the region is
3131     // re-allocated. The only exception to this is if there's an
3132     // evacuation failure and instead of freeing the region we leave
3133     // it in the heap. In that case, we reset these fields during
3134     // evacuation failure handling.
3135     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3136 
3137     // Here's a good place to add any other checks we'd like to
3138     // perform on CSet regions.
3139     return false;
3140   }
3141 };
3142 #endif // ASSERT
3143 
3144 uint G1CollectedHeap::num_task_queues() const {
3145   return _task_queues->size();
3146 }
3147 
3148 #if TASKQUEUE_STATS
3149 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3150   st->print_raw_cr("GC Task Stats");
3151   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3152   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3153 }
3154 
3155 void G1CollectedHeap::print_taskqueue_stats() const {
3156   if (!log_develop_is_enabled(Trace, gc, task, stats)) {
3157     return;
3158   }
3159   LogHandle(gc, task, stats) log;
3160   ResourceMark rm;
3161   outputStream* st = log.trace_stream();
3162 
3163   print_taskqueue_stats_hdr(st);
3164 
3165   TaskQueueStats totals;
3166   const uint n = num_task_queues();
3167   for (uint i = 0; i < n; ++i) {
3168     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3169     totals += task_queue(i)->stats;
3170   }
3171   st->print_raw("tot "); totals.print(st); st->cr();
3172 
3173   DEBUG_ONLY(totals.verify());
3174 }
3175 
3176 void G1CollectedHeap::reset_taskqueue_stats() {
3177   const uint n = num_task_queues();
3178   for (uint i = 0; i < n; ++i) {
3179     task_queue(i)->stats.reset();
3180   }
3181 }
3182 #endif // TASKQUEUE_STATS
3183 
3184 void G1CollectedHeap::wait_for_root_region_scanning() {
3185   double scan_wait_start = os::elapsedTime();
3186   // We have to wait until the CM threads finish scanning the
3187   // root regions as it's the only way to ensure that all the
3188   // objects on them have been correctly scanned before we start
3189   // moving them during the GC.
3190   bool waited = _cm->root_regions()->wait_until_scan_finished();
3191   double wait_time_ms = 0.0;
3192   if (waited) {
3193     double scan_wait_end = os::elapsedTime();
3194     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3195   }
3196   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3197 }
3198 
3199 bool
3200 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3201   assert_at_safepoint(true /* should_be_vm_thread */);
3202   guarantee(!is_gc_active(), "collection is not reentrant");
3203 
3204   if (GCLocker::check_active_before_gc()) {
3205     return false;
3206   }
3207 
3208   _gc_timer_stw->register_gc_start();
3209 
3210   GCIdMark gc_id_mark;
3211   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3212 
3213   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3214   ResourceMark rm;
3215 
3216   wait_for_root_region_scanning();
3217 
3218   print_heap_before_gc();
3219   print_heap_regions();
3220   trace_heap_before_gc(_gc_tracer_stw);
3221 
3222   _verifier->verify_region_sets_optional();
3223   _verifier->verify_dirty_young_regions();
3224 
3225   // This call will decide whether this pause is an initial-mark
3226   // pause. If it is, during_initial_mark_pause() will return true
3227   // for the duration of this pause.
3228   g1_policy()->decide_on_conc_mark_initiation();
3229 
3230   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3231   assert(!collector_state()->during_initial_mark_pause() ||
3232           collector_state()->gcs_are_young(), "sanity");
3233 
3234   // We also do not allow mixed GCs during marking.
3235   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3236 
3237   // Record whether this pause is an initial mark. When the current
3238   // thread has completed its logging output and it's safe to signal
3239   // the CM thread, the flag's value in the policy has been reset.
3240   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3241 
3242   // Inner scope for scope based logging, timers, and stats collection
3243   {
3244     EvacuationInfo evacuation_info;
3245 
3246     if (collector_state()->during_initial_mark_pause()) {
3247       // We are about to start a marking cycle, so we increment the
3248       // full collection counter.
3249       increment_old_marking_cycles_started();
3250       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3251     }
3252 
3253     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3254 
3255     GCTraceCPUTime tcpu;
3256 
3257     FormatBuffer<> gc_string("Pause ");
3258     if (collector_state()->during_initial_mark_pause()) {
3259       gc_string.append("Initial Mark");
3260     } else if (collector_state()->gcs_are_young()) {
3261       gc_string.append("Young");
3262     } else {
3263       gc_string.append("Mixed");
3264     }
3265     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3266 
3267     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3268                                                                   workers()->active_workers(),
3269                                                                   Threads::number_of_non_daemon_threads());
3270     workers()->set_active_workers(active_workers);
3271 
3272     g1_policy()->note_gc_start(active_workers);
3273 
3274     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3275     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3276 
3277     // If the secondary_free_list is not empty, append it to the
3278     // free_list. No need to wait for the cleanup operation to finish;
3279     // the region allocation code will check the secondary_free_list
3280     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3281     // set, skip this step so that the region allocation code has to
3282     // get entries from the secondary_free_list.
3283     if (!G1StressConcRegionFreeing) {
3284       append_secondary_free_list_if_not_empty_with_lock();
3285     }
3286 
3287     G1HeapTransition heap_transition(this);
3288     size_t heap_used_bytes_before_gc = used();
3289 
3290     assert(check_young_list_well_formed(), "young list should be well formed");
3291 
3292     // Don't dynamically change the number of GC threads this early.  A value of
3293     // 0 is used to indicate serial work.  When parallel work is done,
3294     // it will be set.
3295 
3296     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3297       IsGCActiveMark x;
3298 
3299       gc_prologue(false);
3300       increment_total_collections(false /* full gc */);
3301       increment_gc_time_stamp();
3302 
3303       if (VerifyRememberedSets) {
3304         log_info(gc, verify)("[Verifying RemSets before GC]");
3305         VerifyRegionRemSetClosure v_cl;
3306         heap_region_iterate(&v_cl);
3307       }
3308 
3309       _verifier->verify_before_gc();
3310 
3311       _verifier->check_bitmaps("GC Start");
3312 
3313 #if defined(COMPILER2) || INCLUDE_JVMCI
3314       DerivedPointerTable::clear();
3315 #endif
3316 
3317       // Please see comment in g1CollectedHeap.hpp and
3318       // G1CollectedHeap::ref_processing_init() to see how
3319       // reference processing currently works in G1.
3320 
3321       // Enable discovery in the STW reference processor
3322       if (g1_policy()->should_process_references()) {
3323         ref_processor_stw()->enable_discovery();
3324       } else {
3325         ref_processor_stw()->disable_discovery();
3326       }
3327 
3328       {
3329         // We want to temporarily turn off discovery by the
3330         // CM ref processor, if necessary, and turn it back on
3331         // on again later if we do. Using a scoped
3332         // NoRefDiscovery object will do this.
3333         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3334 
3335         // Forget the current alloc region (we might even choose it to be part
3336         // of the collection set!).
3337         _allocator->release_mutator_alloc_region();
3338 
3339         // This timing is only used by the ergonomics to handle our pause target.
3340         // It is unclear why this should not include the full pause. We will
3341         // investigate this in CR 7178365.
3342         //
3343         // Preserving the old comment here if that helps the investigation:
3344         //
3345         // The elapsed time induced by the start time below deliberately elides
3346         // the possible verification above.
3347         double sample_start_time_sec = os::elapsedTime();
3348 
3349         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3350 
3351         if (collector_state()->during_initial_mark_pause()) {
3352           concurrent_mark()->checkpointRootsInitialPre();
3353         }
3354 
3355         g1_policy()->finalize_collection_set(target_pause_time_ms);
3356 
3357         evacuation_info.set_collectionset_regions(collection_set()->region_length());
3358 
3359         // Make sure the remembered sets are up to date. This needs to be
3360         // done before register_humongous_regions_with_cset(), because the
3361         // remembered sets are used there to choose eager reclaim candidates.
3362         // If the remembered sets are not up to date we might miss some
3363         // entries that need to be handled.
3364         g1_rem_set()->cleanupHRRS();
3365 
3366         register_humongous_regions_with_cset();
3367 
3368         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3369 
3370         _cm->note_start_of_gc();
3371         // We call this after finalize_cset() to
3372         // ensure that the CSet has been finalized.
3373         _cm->verify_no_cset_oops();
3374 
3375         if (_hr_printer.is_active()) {
3376           HeapRegion* hr = collection_set()->head();
3377           while (hr != NULL) {
3378             _hr_printer.cset(hr);
3379             hr = hr->next_in_collection_set();
3380           }
3381         }
3382 
3383 #ifdef ASSERT
3384         VerifyCSetClosure cl;
3385         collection_set_iterate(&cl);
3386 #endif // ASSERT
3387 
3388         // Initialize the GC alloc regions.
3389         _allocator->init_gc_alloc_regions(evacuation_info);
3390 
3391         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3392         pre_evacuate_collection_set();
3393 
3394         // Actually do the work...
3395         evacuate_collection_set(evacuation_info, &per_thread_states);
3396 
3397         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3398 
3399         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3400         free_collection_set(collection_set()->head(), evacuation_info, surviving_young_words);
3401 
3402         eagerly_reclaim_humongous_regions();
3403 
3404         collection_set()->clear_head();
3405 
3406         record_obj_copy_mem_stats();
3407         _survivor_evac_stats.adjust_desired_plab_sz();
3408         _old_evac_stats.adjust_desired_plab_sz();
3409 
3410         // Start a new incremental collection set for the next pause.
3411         collection_set()->start_incremental_building();
3412 
3413         clear_cset_fast_test();
3414 
3415         // Don't check the whole heap at this point as the
3416         // GC alloc regions from this pause have been tagged
3417         // as survivors and moved on to the survivor list.
3418         // Survivor regions will fail the !is_young() check.
3419         assert(check_young_list_empty(false /* check_heap */),
3420           "young list should be empty");
3421 
3422         _young_list->reset_auxilary_lists();
3423 
3424         if (evacuation_failed()) {
3425           set_used(recalculate_used());
3426           if (_archive_allocator != NULL) {
3427             _archive_allocator->clear_used();
3428           }
3429           for (uint i = 0; i < ParallelGCThreads; i++) {
3430             if (_evacuation_failed_info_array[i].has_failed()) {
3431               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3432             }
3433           }
3434         } else {
3435           // The "used" of the the collection set have already been subtracted
3436           // when they were freed.  Add in the bytes evacuated.
3437           increase_used(g1_policy()->bytes_copied_during_gc());
3438         }
3439 
3440         if (collector_state()->during_initial_mark_pause()) {
3441           // We have to do this before we notify the CM threads that
3442           // they can start working to make sure that all the
3443           // appropriate initialization is done on the CM object.
3444           concurrent_mark()->checkpointRootsInitialPost();
3445           collector_state()->set_mark_in_progress(true);
3446           // Note that we don't actually trigger the CM thread at
3447           // this point. We do that later when we're sure that
3448           // the current thread has completed its logging output.
3449         }
3450 
3451         allocate_dummy_regions();
3452 
3453         _allocator->init_mutator_alloc_region();
3454 
3455         {
3456           size_t expand_bytes = g1_policy()->expansion_amount();
3457           if (expand_bytes > 0) {
3458             size_t bytes_before = capacity();
3459             // No need for an ergo logging here,
3460             // expansion_amount() does this when it returns a value > 0.
3461             double expand_ms;
3462             if (!expand(expand_bytes, &expand_ms)) {
3463               // We failed to expand the heap. Cannot do anything about it.
3464             }
3465             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3466           }
3467         }
3468 
3469         // We redo the verification but now wrt to the new CSet which
3470         // has just got initialized after the previous CSet was freed.
3471         _cm->verify_no_cset_oops();
3472         _cm->note_end_of_gc();
3473 
3474         // This timing is only used by the ergonomics to handle our pause target.
3475         // It is unclear why this should not include the full pause. We will
3476         // investigate this in CR 7178365.
3477         double sample_end_time_sec = os::elapsedTime();
3478         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3479         size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3480         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3481 
3482         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3483         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3484 
3485         MemoryService::track_memory_usage();
3486 
3487         // In prepare_for_verify() below we'll need to scan the deferred
3488         // update buffers to bring the RSets up-to-date if
3489         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3490         // the update buffers we'll probably need to scan cards on the
3491         // regions we just allocated to (i.e., the GC alloc
3492         // regions). However, during the last GC we called
3493         // set_saved_mark() on all the GC alloc regions, so card
3494         // scanning might skip the [saved_mark_word()...top()] area of
3495         // those regions (i.e., the area we allocated objects into
3496         // during the last GC). But it shouldn't. Given that
3497         // saved_mark_word() is conditional on whether the GC time stamp
3498         // on the region is current or not, by incrementing the GC time
3499         // stamp here we invalidate all the GC time stamps on all the
3500         // regions and saved_mark_word() will simply return top() for
3501         // all the regions. This is a nicer way of ensuring this rather
3502         // than iterating over the regions and fixing them. In fact, the
3503         // GC time stamp increment here also ensures that
3504         // saved_mark_word() will return top() between pauses, i.e.,
3505         // during concurrent refinement. So we don't need the
3506         // is_gc_active() check to decided which top to use when
3507         // scanning cards (see CR 7039627).
3508         increment_gc_time_stamp();
3509 
3510         if (VerifyRememberedSets) {
3511           log_info(gc, verify)("[Verifying RemSets after GC]");
3512           VerifyRegionRemSetClosure v_cl;
3513           heap_region_iterate(&v_cl);
3514         }
3515 
3516         _verifier->verify_after_gc();
3517         _verifier->check_bitmaps("GC End");
3518 
3519         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3520         ref_processor_stw()->verify_no_references_recorded();
3521 
3522         // CM reference discovery will be re-enabled if necessary.
3523       }
3524 
3525 #ifdef TRACESPINNING
3526       ParallelTaskTerminator::print_termination_counts();
3527 #endif
3528 
3529       gc_epilogue(false);
3530     }
3531 
3532     // Print the remainder of the GC log output.
3533     if (evacuation_failed()) {
3534       log_info(gc)("To-space exhausted");
3535     }
3536 
3537     g1_policy()->print_phases();
3538     heap_transition.print();
3539 
3540     // It is not yet to safe to tell the concurrent mark to
3541     // start as we have some optional output below. We don't want the
3542     // output from the concurrent mark thread interfering with this
3543     // logging output either.
3544 
3545     _hrm.verify_optional();
3546     _verifier->verify_region_sets_optional();
3547 
3548     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3549     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3550 
3551     print_heap_after_gc();
3552     print_heap_regions();
3553     trace_heap_after_gc(_gc_tracer_stw);
3554 
3555     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3556     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3557     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3558     // before any GC notifications are raised.
3559     g1mm()->update_sizes();
3560 
3561     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3562     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3563     _gc_timer_stw->register_gc_end();
3564     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3565   }
3566   // It should now be safe to tell the concurrent mark thread to start
3567   // without its logging output interfering with the logging output
3568   // that came from the pause.
3569 
3570   if (should_start_conc_mark) {
3571     // CAUTION: after the doConcurrentMark() call below,
3572     // the concurrent marking thread(s) could be running
3573     // concurrently with us. Make sure that anything after
3574     // this point does not assume that we are the only GC thread
3575     // running. Note: of course, the actual marking work will
3576     // not start until the safepoint itself is released in
3577     // SuspendibleThreadSet::desynchronize().
3578     doConcurrentMark();
3579   }
3580 
3581   return true;
3582 }
3583 
3584 void G1CollectedHeap::restore_preserved_marks() {
3585   G1RestorePreservedMarksTask rpm_task(_preserved_objs);
3586   workers()->run_task(&rpm_task);
3587 }
3588 
3589 void G1CollectedHeap::remove_self_forwarding_pointers() {
3590   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3591   workers()->run_task(&rsfp_task);
3592 }
3593 
3594 void G1CollectedHeap::restore_after_evac_failure() {
3595   double remove_self_forwards_start = os::elapsedTime();
3596 
3597   remove_self_forwarding_pointers();
3598   restore_preserved_marks();
3599 
3600   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3601 }
3602 
3603 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3604   if (!_evacuation_failed) {
3605     _evacuation_failed = true;
3606   }
3607 
3608   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3609 
3610   // We want to call the "for_promotion_failure" version only in the
3611   // case of a promotion failure.
3612   if (m->must_be_preserved_for_promotion_failure(obj)) {
3613     OopAndMarkOop elem(obj, m);
3614     _preserved_objs[worker_id].push(elem);
3615   }
3616 }
3617 
3618 bool G1ParEvacuateFollowersClosure::offer_termination() {
3619   G1ParScanThreadState* const pss = par_scan_state();
3620   start_term_time();
3621   const bool res = terminator()->offer_termination();
3622   end_term_time();
3623   return res;
3624 }
3625 
3626 void G1ParEvacuateFollowersClosure::do_void() {
3627   G1ParScanThreadState* const pss = par_scan_state();
3628   pss->trim_queue();
3629   do {
3630     pss->steal_and_trim_queue(queues());
3631   } while (!offer_termination());
3632 }
3633 
3634 class G1ParTask : public AbstractGangTask {
3635 protected:
3636   G1CollectedHeap*         _g1h;
3637   G1ParScanThreadStateSet* _pss;
3638   RefToScanQueueSet*       _queues;
3639   G1RootProcessor*         _root_processor;
3640   ParallelTaskTerminator   _terminator;
3641   uint                     _n_workers;
3642 
3643 public:
3644   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3645     : AbstractGangTask("G1 collection"),
3646       _g1h(g1h),
3647       _pss(per_thread_states),
3648       _queues(task_queues),
3649       _root_processor(root_processor),
3650       _terminator(n_workers, _queues),
3651       _n_workers(n_workers)
3652   {}
3653 
3654   void work(uint worker_id) {
3655     if (worker_id >= _n_workers) return;  // no work needed this round
3656 
3657     double start_sec = os::elapsedTime();
3658     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3659 
3660     {
3661       ResourceMark rm;
3662       HandleMark   hm;
3663 
3664       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3665 
3666       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3667       pss->set_ref_processor(rp);
3668 
3669       double start_strong_roots_sec = os::elapsedTime();
3670 
3671       _root_processor->evacuate_roots(pss->closures(), worker_id);
3672 
3673       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3674 
3675       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3676       // treating the nmethods visited to act as roots for concurrent marking.
3677       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3678       // objects copied by the current evacuation.
3679       size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3680                                                                              pss->closures()->weak_codeblobs(),
3681                                                                              worker_id);
3682 
3683       _pss->add_cards_scanned(worker_id, cards_scanned);
3684 
3685       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3686 
3687       double term_sec = 0.0;
3688       size_t evac_term_attempts = 0;
3689       {
3690         double start = os::elapsedTime();
3691         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3692         evac.do_void();
3693 
3694         evac_term_attempts = evac.term_attempts();
3695         term_sec = evac.term_time();
3696         double elapsed_sec = os::elapsedTime() - start;
3697         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3698         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3699         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3700       }
3701 
3702       assert(pss->queue_is_empty(), "should be empty");
3703 
3704       if (log_is_enabled(Debug, gc, task, stats)) {
3705         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3706         size_t lab_waste;
3707         size_t lab_undo_waste;
3708         pss->waste(lab_waste, lab_undo_waste);
3709         _g1h->print_termination_stats(worker_id,
3710                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3711                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3712                                       term_sec * 1000.0,                          /* evac term time */
3713                                       evac_term_attempts,                         /* evac term attempts */
3714                                       lab_waste,                                  /* alloc buffer waste */
3715                                       lab_undo_waste                              /* undo waste */
3716                                       );
3717       }
3718 
3719       // Close the inner scope so that the ResourceMark and HandleMark
3720       // destructors are executed here and are included as part of the
3721       // "GC Worker Time".
3722     }
3723     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3724   }
3725 };
3726 
3727 void G1CollectedHeap::print_termination_stats_hdr() {
3728   log_debug(gc, task, stats)("GC Termination Stats");
3729   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3730   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3731   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3732 }
3733 
3734 void G1CollectedHeap::print_termination_stats(uint worker_id,
3735                                               double elapsed_ms,
3736                                               double strong_roots_ms,
3737                                               double term_ms,
3738                                               size_t term_attempts,
3739                                               size_t alloc_buffer_waste,
3740                                               size_t undo_waste) const {
3741   log_debug(gc, task, stats)
3742               ("%3d %9.2f %9.2f %6.2f "
3743                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3744                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3745                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3746                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3747                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3748                alloc_buffer_waste * HeapWordSize / K,
3749                undo_waste * HeapWordSize / K);
3750 }
3751 
3752 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3753 private:
3754   BoolObjectClosure* _is_alive;
3755   int _initial_string_table_size;
3756   int _initial_symbol_table_size;
3757 
3758   bool  _process_strings;
3759   int _strings_processed;
3760   int _strings_removed;
3761 
3762   bool  _process_symbols;
3763   int _symbols_processed;
3764   int _symbols_removed;
3765 
3766 public:
3767   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3768     AbstractGangTask("String/Symbol Unlinking"),
3769     _is_alive(is_alive),
3770     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3771     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3772 
3773     _initial_string_table_size = StringTable::the_table()->table_size();
3774     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3775     if (process_strings) {
3776       StringTable::clear_parallel_claimed_index();
3777     }
3778     if (process_symbols) {
3779       SymbolTable::clear_parallel_claimed_index();
3780     }
3781   }
3782 
3783   ~G1StringSymbolTableUnlinkTask() {
3784     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3785               "claim value %d after unlink less than initial string table size %d",
3786               StringTable::parallel_claimed_index(), _initial_string_table_size);
3787     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3788               "claim value %d after unlink less than initial symbol table size %d",
3789               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3790 
3791     log_debug(gc, stringdedup)("Cleaned string and symbol table, "
3792                                "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3793                                "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3794                                strings_processed(), strings_removed(),
3795                                symbols_processed(), symbols_removed());
3796   }
3797 
3798   void work(uint worker_id) {
3799     int strings_processed = 0;
3800     int strings_removed = 0;
3801     int symbols_processed = 0;
3802     int symbols_removed = 0;
3803     if (_process_strings) {
3804       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3805       Atomic::add(strings_processed, &_strings_processed);
3806       Atomic::add(strings_removed, &_strings_removed);
3807     }
3808     if (_process_symbols) {
3809       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3810       Atomic::add(symbols_processed, &_symbols_processed);
3811       Atomic::add(symbols_removed, &_symbols_removed);
3812     }
3813   }
3814 
3815   size_t strings_processed() const { return (size_t)_strings_processed; }
3816   size_t strings_removed()   const { return (size_t)_strings_removed; }
3817 
3818   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3819   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3820 };
3821 
3822 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3823 private:
3824   static Monitor* _lock;
3825 
3826   BoolObjectClosure* const _is_alive;
3827   const bool               _unloading_occurred;
3828   const uint               _num_workers;
3829 
3830   // Variables used to claim nmethods.
3831   nmethod* _first_nmethod;
3832   volatile nmethod* _claimed_nmethod;
3833 
3834   // The list of nmethods that need to be processed by the second pass.
3835   volatile nmethod* _postponed_list;
3836   volatile uint     _num_entered_barrier;
3837 
3838  public:
3839   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3840       _is_alive(is_alive),
3841       _unloading_occurred(unloading_occurred),
3842       _num_workers(num_workers),
3843       _first_nmethod(NULL),
3844       _claimed_nmethod(NULL),
3845       _postponed_list(NULL),
3846       _num_entered_barrier(0)
3847   {
3848     nmethod::increase_unloading_clock();
3849     // Get first alive nmethod
3850     NMethodIterator iter = NMethodIterator();
3851     if(iter.next_alive()) {
3852       _first_nmethod = iter.method();
3853     }
3854     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
3855   }
3856 
3857   ~G1CodeCacheUnloadingTask() {
3858     CodeCache::verify_clean_inline_caches();
3859 
3860     CodeCache::set_needs_cache_clean(false);
3861     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3862 
3863     CodeCache::verify_icholder_relocations();
3864   }
3865 
3866  private:
3867   void add_to_postponed_list(nmethod* nm) {
3868       nmethod* old;
3869       do {
3870         old = (nmethod*)_postponed_list;
3871         nm->set_unloading_next(old);
3872       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3873   }
3874 
3875   void clean_nmethod(nmethod* nm) {
3876     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3877 
3878     if (postponed) {
3879       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3880       add_to_postponed_list(nm);
3881     }
3882 
3883     // Mark that this thread has been cleaned/unloaded.
3884     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3885     nm->set_unloading_clock(nmethod::global_unloading_clock());
3886   }
3887 
3888   void clean_nmethod_postponed(nmethod* nm) {
3889     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3890   }
3891 
3892   static const int MaxClaimNmethods = 16;
3893 
3894   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
3895     nmethod* first;
3896     NMethodIterator last;
3897 
3898     do {
3899       *num_claimed_nmethods = 0;
3900 
3901       first = (nmethod*)_claimed_nmethod;
3902       last = NMethodIterator(first);
3903 
3904       if (first != NULL) {
3905 
3906         for (int i = 0; i < MaxClaimNmethods; i++) {
3907           if (!last.next_alive()) {
3908             break;
3909           }
3910           claimed_nmethods[i] = last.method();
3911           (*num_claimed_nmethods)++;
3912         }
3913       }
3914 
3915     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3916   }
3917 
3918   nmethod* claim_postponed_nmethod() {
3919     nmethod* claim;
3920     nmethod* next;
3921 
3922     do {
3923       claim = (nmethod*)_postponed_list;
3924       if (claim == NULL) {
3925         return NULL;
3926       }
3927 
3928       next = claim->unloading_next();
3929 
3930     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3931 
3932     return claim;
3933   }
3934 
3935  public:
3936   // Mark that we're done with the first pass of nmethod cleaning.
3937   void barrier_mark(uint worker_id) {
3938     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3939     _num_entered_barrier++;
3940     if (_num_entered_barrier == _num_workers) {
3941       ml.notify_all();
3942     }
3943   }
3944 
3945   // See if we have to wait for the other workers to
3946   // finish their first-pass nmethod cleaning work.
3947   void barrier_wait(uint worker_id) {
3948     if (_num_entered_barrier < _num_workers) {
3949       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3950       while (_num_entered_barrier < _num_workers) {
3951           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3952       }
3953     }
3954   }
3955 
3956   // Cleaning and unloading of nmethods. Some work has to be postponed
3957   // to the second pass, when we know which nmethods survive.
3958   void work_first_pass(uint worker_id) {
3959     // The first nmethods is claimed by the first worker.
3960     if (worker_id == 0 && _first_nmethod != NULL) {
3961       clean_nmethod(_first_nmethod);
3962       _first_nmethod = NULL;
3963     }
3964 
3965     int num_claimed_nmethods;
3966     nmethod* claimed_nmethods[MaxClaimNmethods];
3967 
3968     while (true) {
3969       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3970 
3971       if (num_claimed_nmethods == 0) {
3972         break;
3973       }
3974 
3975       for (int i = 0; i < num_claimed_nmethods; i++) {
3976         clean_nmethod(claimed_nmethods[i]);
3977       }
3978     }
3979   }
3980 
3981   void work_second_pass(uint worker_id) {
3982     nmethod* nm;
3983     // Take care of postponed nmethods.
3984     while ((nm = claim_postponed_nmethod()) != NULL) {
3985       clean_nmethod_postponed(nm);
3986     }
3987   }
3988 };
3989 
3990 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3991 
3992 class G1KlassCleaningTask : public StackObj {
3993   BoolObjectClosure*                      _is_alive;
3994   volatile jint                           _clean_klass_tree_claimed;
3995   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3996 
3997  public:
3998   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3999       _is_alive(is_alive),
4000       _clean_klass_tree_claimed(0),
4001       _klass_iterator() {
4002   }
4003 
4004  private:
4005   bool claim_clean_klass_tree_task() {
4006     if (_clean_klass_tree_claimed) {
4007       return false;
4008     }
4009 
4010     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4011   }
4012 
4013   InstanceKlass* claim_next_klass() {
4014     Klass* klass;
4015     do {
4016       klass =_klass_iterator.next_klass();
4017     } while (klass != NULL && !klass->is_instance_klass());
4018 
4019     // this can be null so don't call InstanceKlass::cast
4020     return static_cast<InstanceKlass*>(klass);
4021   }
4022 
4023 public:
4024 
4025   void clean_klass(InstanceKlass* ik) {
4026     ik->clean_weak_instanceklass_links(_is_alive);
4027   }
4028 
4029   void work() {
4030     ResourceMark rm;
4031 
4032     // One worker will clean the subklass/sibling klass tree.
4033     if (claim_clean_klass_tree_task()) {
4034       Klass::clean_subklass_tree(_is_alive);
4035     }
4036 
4037     // All workers will help cleaning the classes,
4038     InstanceKlass* klass;
4039     while ((klass = claim_next_klass()) != NULL) {
4040       clean_klass(klass);
4041     }
4042   }
4043 };
4044 
4045 // To minimize the remark pause times, the tasks below are done in parallel.
4046 class G1ParallelCleaningTask : public AbstractGangTask {
4047 private:
4048   G1StringSymbolTableUnlinkTask _string_symbol_task;
4049   G1CodeCacheUnloadingTask      _code_cache_task;
4050   G1KlassCleaningTask           _klass_cleaning_task;
4051 
4052 public:
4053   // The constructor is run in the VMThread.
4054   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4055       AbstractGangTask("Parallel Cleaning"),
4056       _string_symbol_task(is_alive, process_strings, process_symbols),
4057       _code_cache_task(num_workers, is_alive, unloading_occurred),
4058       _klass_cleaning_task(is_alive) {
4059   }
4060 
4061   // The parallel work done by all worker threads.
4062   void work(uint worker_id) {
4063     // Do first pass of code cache cleaning.
4064     _code_cache_task.work_first_pass(worker_id);
4065 
4066     // Let the threads mark that the first pass is done.
4067     _code_cache_task.barrier_mark(worker_id);
4068 
4069     // Clean the Strings and Symbols.
4070     _string_symbol_task.work(worker_id);
4071 
4072     // Wait for all workers to finish the first code cache cleaning pass.
4073     _code_cache_task.barrier_wait(worker_id);
4074 
4075     // Do the second code cache cleaning work, which realize on
4076     // the liveness information gathered during the first pass.
4077     _code_cache_task.work_second_pass(worker_id);
4078 
4079     // Clean all klasses that were not unloaded.
4080     _klass_cleaning_task.work();
4081   }
4082 };
4083 
4084 
4085 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4086                                         bool process_strings,
4087                                         bool process_symbols,
4088                                         bool class_unloading_occurred) {
4089   uint n_workers = workers()->active_workers();
4090 
4091   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4092                                         n_workers, class_unloading_occurred);
4093   workers()->run_task(&g1_unlink_task);
4094 }
4095 
4096 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4097                                                      bool process_strings, bool process_symbols) {
4098   {
4099     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4100     workers()->run_task(&g1_unlink_task);
4101   }
4102 
4103   if (G1StringDedup::is_enabled()) {
4104     G1StringDedup::unlink(is_alive);
4105   }
4106 }
4107 
4108 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4109  private:
4110   DirtyCardQueueSet* _queue;
4111   G1CollectedHeap* _g1h;
4112  public:
4113   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4114     _queue(queue), _g1h(g1h) { }
4115 
4116   virtual void work(uint worker_id) {
4117     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4118     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4119 
4120     RedirtyLoggedCardTableEntryClosure cl(_g1h);
4121     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4122 
4123     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4124   }
4125 };
4126 
4127 void G1CollectedHeap::redirty_logged_cards() {
4128   double redirty_logged_cards_start = os::elapsedTime();
4129 
4130   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4131   dirty_card_queue_set().reset_for_par_iteration();
4132   workers()->run_task(&redirty_task);
4133 
4134   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4135   dcq.merge_bufferlists(&dirty_card_queue_set());
4136   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4137 
4138   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4139 }
4140 
4141 // Weak Reference Processing support
4142 
4143 // An always "is_alive" closure that is used to preserve referents.
4144 // If the object is non-null then it's alive.  Used in the preservation
4145 // of referent objects that are pointed to by reference objects
4146 // discovered by the CM ref processor.
4147 class G1AlwaysAliveClosure: public BoolObjectClosure {
4148   G1CollectedHeap* _g1;
4149 public:
4150   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4151   bool do_object_b(oop p) {
4152     if (p != NULL) {
4153       return true;
4154     }
4155     return false;
4156   }
4157 };
4158 
4159 bool G1STWIsAliveClosure::do_object_b(oop p) {
4160   // An object is reachable if it is outside the collection set,
4161   // or is inside and copied.
4162   return !_g1->is_in_cset(p) || p->is_forwarded();
4163 }
4164 
4165 // Non Copying Keep Alive closure
4166 class G1KeepAliveClosure: public OopClosure {
4167   G1CollectedHeap* _g1;
4168 public:
4169   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4170   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4171   void do_oop(oop* p) {
4172     oop obj = *p;
4173     assert(obj != NULL, "the caller should have filtered out NULL values");
4174 
4175     const InCSetState cset_state = _g1->in_cset_state(obj);
4176     if (!cset_state.is_in_cset_or_humongous()) {
4177       return;
4178     }
4179     if (cset_state.is_in_cset()) {
4180       assert( obj->is_forwarded(), "invariant" );
4181       *p = obj->forwardee();
4182     } else {
4183       assert(!obj->is_forwarded(), "invariant" );
4184       assert(cset_state.is_humongous(),
4185              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4186       _g1->set_humongous_is_live(obj);
4187     }
4188   }
4189 };
4190 
4191 // Copying Keep Alive closure - can be called from both
4192 // serial and parallel code as long as different worker
4193 // threads utilize different G1ParScanThreadState instances
4194 // and different queues.
4195 
4196 class G1CopyingKeepAliveClosure: public OopClosure {
4197   G1CollectedHeap*         _g1h;
4198   OopClosure*              _copy_non_heap_obj_cl;
4199   G1ParScanThreadState*    _par_scan_state;
4200 
4201 public:
4202   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4203                             OopClosure* non_heap_obj_cl,
4204                             G1ParScanThreadState* pss):
4205     _g1h(g1h),
4206     _copy_non_heap_obj_cl(non_heap_obj_cl),
4207     _par_scan_state(pss)
4208   {}
4209 
4210   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4211   virtual void do_oop(      oop* p) { do_oop_work(p); }
4212 
4213   template <class T> void do_oop_work(T* p) {
4214     oop obj = oopDesc::load_decode_heap_oop(p);
4215 
4216     if (_g1h->is_in_cset_or_humongous(obj)) {
4217       // If the referent object has been forwarded (either copied
4218       // to a new location or to itself in the event of an
4219       // evacuation failure) then we need to update the reference
4220       // field and, if both reference and referent are in the G1
4221       // heap, update the RSet for the referent.
4222       //
4223       // If the referent has not been forwarded then we have to keep
4224       // it alive by policy. Therefore we have copy the referent.
4225       //
4226       // If the reference field is in the G1 heap then we can push
4227       // on the PSS queue. When the queue is drained (after each
4228       // phase of reference processing) the object and it's followers
4229       // will be copied, the reference field set to point to the
4230       // new location, and the RSet updated. Otherwise we need to
4231       // use the the non-heap or metadata closures directly to copy
4232       // the referent object and update the pointer, while avoiding
4233       // updating the RSet.
4234 
4235       if (_g1h->is_in_g1_reserved(p)) {
4236         _par_scan_state->push_on_queue(p);
4237       } else {
4238         assert(!Metaspace::contains((const void*)p),
4239                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4240         _copy_non_heap_obj_cl->do_oop(p);
4241       }
4242     }
4243   }
4244 };
4245 
4246 // Serial drain queue closure. Called as the 'complete_gc'
4247 // closure for each discovered list in some of the
4248 // reference processing phases.
4249 
4250 class G1STWDrainQueueClosure: public VoidClosure {
4251 protected:
4252   G1CollectedHeap* _g1h;
4253   G1ParScanThreadState* _par_scan_state;
4254 
4255   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4256 
4257 public:
4258   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4259     _g1h(g1h),
4260     _par_scan_state(pss)
4261   { }
4262 
4263   void do_void() {
4264     G1ParScanThreadState* const pss = par_scan_state();
4265     pss->trim_queue();
4266   }
4267 };
4268 
4269 // Parallel Reference Processing closures
4270 
4271 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4272 // processing during G1 evacuation pauses.
4273 
4274 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4275 private:
4276   G1CollectedHeap*          _g1h;
4277   G1ParScanThreadStateSet*  _pss;
4278   RefToScanQueueSet*        _queues;
4279   WorkGang*                 _workers;
4280   uint                      _active_workers;
4281 
4282 public:
4283   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4284                            G1ParScanThreadStateSet* per_thread_states,
4285                            WorkGang* workers,
4286                            RefToScanQueueSet *task_queues,
4287                            uint n_workers) :
4288     _g1h(g1h),
4289     _pss(per_thread_states),
4290     _queues(task_queues),
4291     _workers(workers),
4292     _active_workers(n_workers)
4293   {
4294     assert(n_workers > 0, "shouldn't call this otherwise");
4295   }
4296 
4297   // Executes the given task using concurrent marking worker threads.
4298   virtual void execute(ProcessTask& task);
4299   virtual void execute(EnqueueTask& task);
4300 };
4301 
4302 // Gang task for possibly parallel reference processing
4303 
4304 class G1STWRefProcTaskProxy: public AbstractGangTask {
4305   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4306   ProcessTask&     _proc_task;
4307   G1CollectedHeap* _g1h;
4308   G1ParScanThreadStateSet* _pss;
4309   RefToScanQueueSet* _task_queues;
4310   ParallelTaskTerminator* _terminator;
4311 
4312 public:
4313   G1STWRefProcTaskProxy(ProcessTask& proc_task,
4314                         G1CollectedHeap* g1h,
4315                         G1ParScanThreadStateSet* per_thread_states,
4316                         RefToScanQueueSet *task_queues,
4317                         ParallelTaskTerminator* terminator) :
4318     AbstractGangTask("Process reference objects in parallel"),
4319     _proc_task(proc_task),
4320     _g1h(g1h),
4321     _pss(per_thread_states),
4322     _task_queues(task_queues),
4323     _terminator(terminator)
4324   {}
4325 
4326   virtual void work(uint worker_id) {
4327     // The reference processing task executed by a single worker.
4328     ResourceMark rm;
4329     HandleMark   hm;
4330 
4331     G1STWIsAliveClosure is_alive(_g1h);
4332 
4333     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4334     pss->set_ref_processor(NULL);
4335 
4336     // Keep alive closure.
4337     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4338 
4339     // Complete GC closure
4340     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4341 
4342     // Call the reference processing task's work routine.
4343     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4344 
4345     // Note we cannot assert that the refs array is empty here as not all
4346     // of the processing tasks (specifically phase2 - pp2_work) execute
4347     // the complete_gc closure (which ordinarily would drain the queue) so
4348     // the queue may not be empty.
4349   }
4350 };
4351 
4352 // Driver routine for parallel reference processing.
4353 // Creates an instance of the ref processing gang
4354 // task and has the worker threads execute it.
4355 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4356   assert(_workers != NULL, "Need parallel worker threads.");
4357 
4358   ParallelTaskTerminator terminator(_active_workers, _queues);
4359   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4360 
4361   _workers->run_task(&proc_task_proxy);
4362 }
4363 
4364 // Gang task for parallel reference enqueueing.
4365 
4366 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4367   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4368   EnqueueTask& _enq_task;
4369 
4370 public:
4371   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4372     AbstractGangTask("Enqueue reference objects in parallel"),
4373     _enq_task(enq_task)
4374   { }
4375 
4376   virtual void work(uint worker_id) {
4377     _enq_task.work(worker_id);
4378   }
4379 };
4380 
4381 // Driver routine for parallel reference enqueueing.
4382 // Creates an instance of the ref enqueueing gang
4383 // task and has the worker threads execute it.
4384 
4385 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4386   assert(_workers != NULL, "Need parallel worker threads.");
4387 
4388   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4389 
4390   _workers->run_task(&enq_task_proxy);
4391 }
4392 
4393 // End of weak reference support closures
4394 
4395 // Abstract task used to preserve (i.e. copy) any referent objects
4396 // that are in the collection set and are pointed to by reference
4397 // objects discovered by the CM ref processor.
4398 
4399 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4400 protected:
4401   G1CollectedHeap*         _g1h;
4402   G1ParScanThreadStateSet* _pss;
4403   RefToScanQueueSet*       _queues;
4404   ParallelTaskTerminator   _terminator;
4405   uint                     _n_workers;
4406 
4407 public:
4408   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4409     AbstractGangTask("ParPreserveCMReferents"),
4410     _g1h(g1h),
4411     _pss(per_thread_states),
4412     _queues(task_queues),
4413     _terminator(workers, _queues),
4414     _n_workers(workers)
4415   { }
4416 
4417   void work(uint worker_id) {
4418     G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4419 
4420     ResourceMark rm;
4421     HandleMark   hm;
4422 
4423     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4424     pss->set_ref_processor(NULL);
4425     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4426 
4427     // Is alive closure
4428     G1AlwaysAliveClosure always_alive(_g1h);
4429 
4430     // Copying keep alive closure. Applied to referent objects that need
4431     // to be copied.
4432     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4433 
4434     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4435 
4436     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4437     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4438 
4439     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4440     // So this must be true - but assert just in case someone decides to
4441     // change the worker ids.
4442     assert(worker_id < limit, "sanity");
4443     assert(!rp->discovery_is_atomic(), "check this code");
4444 
4445     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4446     for (uint idx = worker_id; idx < limit; idx += stride) {
4447       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4448 
4449       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4450       while (iter.has_next()) {
4451         // Since discovery is not atomic for the CM ref processor, we
4452         // can see some null referent objects.
4453         iter.load_ptrs(DEBUG_ONLY(true));
4454         oop ref = iter.obj();
4455 
4456         // This will filter nulls.
4457         if (iter.is_referent_alive()) {
4458           iter.make_referent_alive();
4459         }
4460         iter.move_to_next();
4461       }
4462     }
4463 
4464     // Drain the queue - which may cause stealing
4465     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4466     drain_queue.do_void();
4467     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4468     assert(pss->queue_is_empty(), "should be");
4469   }
4470 };
4471 
4472 void G1CollectedHeap::process_weak_jni_handles() {
4473   double ref_proc_start = os::elapsedTime();
4474 
4475   G1STWIsAliveClosure is_alive(this);
4476   G1KeepAliveClosure keep_alive(this);
4477   JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4478 
4479   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4480   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4481 }
4482 
4483 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4484   double preserve_cm_referents_start = os::elapsedTime();
4485   // Any reference objects, in the collection set, that were 'discovered'
4486   // by the CM ref processor should have already been copied (either by
4487   // applying the external root copy closure to the discovered lists, or
4488   // by following an RSet entry).
4489   //
4490   // But some of the referents, that are in the collection set, that these
4491   // reference objects point to may not have been copied: the STW ref
4492   // processor would have seen that the reference object had already
4493   // been 'discovered' and would have skipped discovering the reference,
4494   // but would not have treated the reference object as a regular oop.
4495   // As a result the copy closure would not have been applied to the
4496   // referent object.
4497   //
4498   // We need to explicitly copy these referent objects - the references
4499   // will be processed at the end of remarking.
4500   //
4501   // We also need to do this copying before we process the reference
4502   // objects discovered by the STW ref processor in case one of these
4503   // referents points to another object which is also referenced by an
4504   // object discovered by the STW ref processor.
4505 
4506   uint no_of_gc_workers = workers()->active_workers();
4507 
4508   G1ParPreserveCMReferentsTask keep_cm_referents(this,
4509                                                  per_thread_states,
4510                                                  no_of_gc_workers,
4511                                                  _task_queues);
4512   workers()->run_task(&keep_cm_referents);
4513 
4514   g1_policy()->phase_times()->record_preserve_cm_referents_time_ms((os::elapsedTime() - preserve_cm_referents_start) * 1000.0);
4515 }
4516 
4517 // Weak Reference processing during an evacuation pause (part 1).
4518 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4519   double ref_proc_start = os::elapsedTime();
4520 
4521   ReferenceProcessor* rp = _ref_processor_stw;
4522   assert(rp->discovery_enabled(), "should have been enabled");
4523 
4524   // Closure to test whether a referent is alive.
4525   G1STWIsAliveClosure is_alive(this);
4526 
4527   // Even when parallel reference processing is enabled, the processing
4528   // of JNI refs is serial and performed serially by the current thread
4529   // rather than by a worker. The following PSS will be used for processing
4530   // JNI refs.
4531 
4532   // Use only a single queue for this PSS.
4533   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4534   pss->set_ref_processor(NULL);
4535   assert(pss->queue_is_empty(), "pre-condition");
4536 
4537   // Keep alive closure.
4538   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4539 
4540   // Serial Complete GC closure
4541   G1STWDrainQueueClosure drain_queue(this, pss);
4542 
4543   // Setup the soft refs policy...
4544   rp->setup_policy(false);
4545 
4546   ReferenceProcessorStats stats;
4547   if (!rp->processing_is_mt()) {
4548     // Serial reference processing...
4549     stats = rp->process_discovered_references(&is_alive,
4550                                               &keep_alive,
4551                                               &drain_queue,
4552                                               NULL,
4553                                               _gc_timer_stw);
4554   } else {
4555     uint no_of_gc_workers = workers()->active_workers();
4556 
4557     // Parallel reference processing
4558     assert(rp->num_q() == no_of_gc_workers, "sanity");
4559     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
4560 
4561     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4562     stats = rp->process_discovered_references(&is_alive,
4563                                               &keep_alive,
4564                                               &drain_queue,
4565                                               &par_task_executor,
4566                                               _gc_timer_stw);
4567   }
4568 
4569   _gc_tracer_stw->report_gc_reference_stats(stats);
4570 
4571   // We have completed copying any necessary live referent objects.
4572   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4573 
4574   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4575   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4576 }
4577 
4578 // Weak Reference processing during an evacuation pause (part 2).
4579 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4580   double ref_enq_start = os::elapsedTime();
4581 
4582   ReferenceProcessor* rp = _ref_processor_stw;
4583   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4584 
4585   // Now enqueue any remaining on the discovered lists on to
4586   // the pending list.
4587   if (!rp->processing_is_mt()) {
4588     // Serial reference processing...
4589     rp->enqueue_discovered_references();
4590   } else {
4591     // Parallel reference enqueueing
4592 
4593     uint n_workers = workers()->active_workers();
4594 
4595     assert(rp->num_q() == n_workers, "sanity");
4596     assert(n_workers <= rp->max_num_q(), "sanity");
4597 
4598     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4599     rp->enqueue_discovered_references(&par_task_executor);
4600   }
4601 
4602   rp->verify_no_references_recorded();
4603   assert(!rp->discovery_enabled(), "should have been disabled");
4604 
4605   // FIXME
4606   // CM's reference processing also cleans up the string and symbol tables.
4607   // Should we do that here also? We could, but it is a serial operation
4608   // and could significantly increase the pause time.
4609 
4610   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4611   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4612 }
4613 
4614 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4615   double merge_pss_time_start = os::elapsedTime();
4616   per_thread_states->flush();
4617   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4618 }
4619 
4620 void G1CollectedHeap::pre_evacuate_collection_set() {
4621   _expand_heap_after_alloc_failure = true;
4622   _evacuation_failed = false;
4623 
4624   // Disable the hot card cache.
4625   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4626   hot_card_cache->reset_hot_cache_claimed_index();
4627   hot_card_cache->set_use_cache(false);
4628 
4629   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4630 }
4631 
4632 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4633   // Should G1EvacuationFailureALot be in effect for this GC?
4634   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4635 
4636   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4637   double start_par_time_sec = os::elapsedTime();
4638   double end_par_time_sec;
4639 
4640   {
4641     const uint n_workers = workers()->active_workers();
4642     G1RootProcessor root_processor(this, n_workers);
4643     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4644     // InitialMark needs claim bits to keep track of the marked-through CLDs.
4645     if (collector_state()->during_initial_mark_pause()) {
4646       ClassLoaderDataGraph::clear_claimed_marks();
4647     }
4648 
4649     print_termination_stats_hdr();
4650 
4651     workers()->run_task(&g1_par_task);
4652     end_par_time_sec = os::elapsedTime();
4653 
4654     // Closing the inner scope will execute the destructor
4655     // for the G1RootProcessor object. We record the current
4656     // elapsed time before closing the scope so that time
4657     // taken for the destructor is NOT included in the
4658     // reported parallel time.
4659   }
4660 
4661   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4662 
4663   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4664   phase_times->record_par_time(par_time_ms);
4665 
4666   double code_root_fixup_time_ms =
4667         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4668   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4669 }
4670 
4671 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4672   // Process any discovered reference objects - we have
4673   // to do this _before_ we retire the GC alloc regions
4674   // as we may have to copy some 'reachable' referent
4675   // objects (and their reachable sub-graphs) that were
4676   // not copied during the pause.
4677   if (g1_policy()->should_process_references()) {
4678     preserve_cm_referents(per_thread_states);
4679     process_discovered_references(per_thread_states);
4680   } else {
4681     ref_processor_stw()->verify_no_references_recorded();
4682     process_weak_jni_handles();
4683   }
4684 
4685   if (G1StringDedup::is_enabled()) {
4686     double fixup_start = os::elapsedTime();
4687 
4688     G1STWIsAliveClosure is_alive(this);
4689     G1KeepAliveClosure keep_alive(this);
4690     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4691 
4692     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4693     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4694   }
4695 
4696   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4697 
4698   if (evacuation_failed()) {
4699     restore_after_evac_failure();
4700 
4701     // Reset the G1EvacuationFailureALot counters and flags
4702     // Note: the values are reset only when an actual
4703     // evacuation failure occurs.
4704     NOT_PRODUCT(reset_evacuation_should_fail();)
4705   }
4706 
4707   // Enqueue any remaining references remaining on the STW
4708   // reference processor's discovered lists. We need to do
4709   // this after the card table is cleaned (and verified) as
4710   // the act of enqueueing entries on to the pending list
4711   // will log these updates (and dirty their associated
4712   // cards). We need these updates logged to update any
4713   // RSets.
4714   if (g1_policy()->should_process_references()) {
4715     enqueue_discovered_references(per_thread_states);
4716   } else {
4717     g1_policy()->phase_times()->record_ref_enq_time(0);
4718   }
4719 
4720   _allocator->release_gc_alloc_regions(evacuation_info);
4721 
4722   merge_per_thread_state_info(per_thread_states);
4723 
4724   // Reset and re-enable the hot card cache.
4725   // Note the counts for the cards in the regions in the
4726   // collection set are reset when the collection set is freed.
4727   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4728   hot_card_cache->reset_hot_cache();
4729   hot_card_cache->set_use_cache(true);
4730 
4731   purge_code_root_memory();
4732 
4733   redirty_logged_cards();
4734 #if defined(COMPILER2) || INCLUDE_JVMCI
4735   DerivedPointerTable::update_pointers();
4736 #endif
4737 }
4738 
4739 void G1CollectedHeap::record_obj_copy_mem_stats() {
4740   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4741 
4742   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4743                                                create_g1_evac_summary(&_old_evac_stats));
4744 }
4745 
4746 void G1CollectedHeap::free_region(HeapRegion* hr,
4747                                   FreeRegionList* free_list,
4748                                   bool par,
4749                                   bool locked) {
4750   assert(!hr->is_free(), "the region should not be free");
4751   assert(!hr->is_empty(), "the region should not be empty");
4752   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4753   assert(free_list != NULL, "pre-condition");
4754 
4755   if (G1VerifyBitmaps) {
4756     MemRegion mr(hr->bottom(), hr->end());
4757     concurrent_mark()->clearRangePrevBitmap(mr);
4758   }
4759 
4760   // Clear the card counts for this region.
4761   // Note: we only need to do this if the region is not young
4762   // (since we don't refine cards in young regions).
4763   if (!hr->is_young()) {
4764     _cg1r->hot_card_cache()->reset_card_counts(hr);
4765   }
4766   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
4767   free_list->add_ordered(hr);
4768 }
4769 
4770 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4771                                             FreeRegionList* free_list,
4772                                             bool par) {
4773   assert(hr->is_humongous(), "this is only for humongous regions");
4774   assert(free_list != NULL, "pre-condition");
4775   hr->clear_humongous();
4776   free_region(hr, free_list, par);
4777 }
4778 
4779 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4780                                            const uint humongous_regions_removed) {
4781   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4782     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4783     _old_set.bulk_remove(old_regions_removed);
4784     _humongous_set.bulk_remove(humongous_regions_removed);
4785   }
4786 
4787 }
4788 
4789 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4790   assert(list != NULL, "list can't be null");
4791   if (!list->is_empty()) {
4792     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4793     _hrm.insert_list_into_free_list(list);
4794   }
4795 }
4796 
4797 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4798   decrease_used(bytes);
4799 }
4800 
4801 class G1ParCleanupCTTask : public AbstractGangTask {
4802   G1SATBCardTableModRefBS* _ct_bs;
4803   G1CollectedHeap* _g1h;
4804   HeapRegion* volatile _su_head;
4805 public:
4806   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
4807                      G1CollectedHeap* g1h) :
4808     AbstractGangTask("G1 Par Cleanup CT Task"),
4809     _ct_bs(ct_bs), _g1h(g1h) { }
4810 
4811   void work(uint worker_id) {
4812     HeapRegion* r;
4813     while (r = _g1h->pop_dirty_cards_region()) {
4814       clear_cards(r);
4815     }
4816   }
4817 
4818   void clear_cards(HeapRegion* r) {
4819     // Cards of the survivors should have already been dirtied.
4820     if (!r->is_survivor()) {
4821       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4822     }
4823   }
4824 };
4825 
4826 class G1ParScrubRemSetTask: public AbstractGangTask {
4827 protected:
4828   G1RemSet* _g1rs;
4829   BitMap* _region_bm;
4830   BitMap* _card_bm;
4831   HeapRegionClaimer _hrclaimer;
4832 
4833 public:
4834   G1ParScrubRemSetTask(G1RemSet* g1_rs, BitMap* region_bm, BitMap* card_bm, uint num_workers) :
4835     AbstractGangTask("G1 ScrubRS"),
4836     _g1rs(g1_rs),
4837     _region_bm(region_bm),
4838     _card_bm(card_bm),
4839     _hrclaimer(num_workers) {
4840   }
4841 
4842   void work(uint worker_id) {
4843     _g1rs->scrub(_region_bm, _card_bm, worker_id, &_hrclaimer);
4844   }
4845 };
4846 
4847 void G1CollectedHeap::scrub_rem_set(BitMap* region_bm, BitMap* card_bm) {
4848   uint num_workers = workers()->active_workers();
4849   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), region_bm, card_bm, num_workers);
4850   workers()->run_task(&g1_par_scrub_rs_task);
4851 }
4852 
4853 void G1CollectedHeap::cleanUpCardTable() {
4854   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
4855   double start = os::elapsedTime();
4856 
4857   {
4858     // Iterate over the dirty cards region list.
4859     G1ParCleanupCTTask cleanup_task(ct_bs, this);
4860 
4861     workers()->run_task(&cleanup_task);
4862 #ifndef PRODUCT
4863     _verifier->verify_card_table_cleanup();
4864 #endif
4865   }
4866 
4867   double elapsed = os::elapsedTime() - start;
4868   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
4869 }
4870 
4871 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4872   size_t pre_used = 0;
4873   FreeRegionList local_free_list("Local List for CSet Freeing");
4874 
4875   double young_time_ms     = 0.0;
4876   double non_young_time_ms = 0.0;
4877 
4878   // Since the collection set is a superset of the the young list,
4879   // all we need to do to clear the young list is clear its
4880   // head and length, and unlink any young regions in the code below
4881   _young_list->clear();
4882 
4883   G1CollectorPolicy* policy = g1_policy();
4884 
4885   double start_sec = os::elapsedTime();
4886   bool non_young = true;
4887 
4888   HeapRegion* cur = cs_head;
4889   int age_bound = -1;
4890   size_t rs_lengths = 0;
4891 
4892   while (cur != NULL) {
4893     assert(!is_on_master_free_list(cur), "sanity");
4894     if (non_young) {
4895       if (cur->is_young()) {
4896         double end_sec = os::elapsedTime();
4897         double elapsed_ms = (end_sec - start_sec) * 1000.0;
4898         non_young_time_ms += elapsed_ms;
4899 
4900         start_sec = os::elapsedTime();
4901         non_young = false;
4902       }
4903     } else {
4904       if (!cur->is_young()) {
4905         double end_sec = os::elapsedTime();
4906         double elapsed_ms = (end_sec - start_sec) * 1000.0;
4907         young_time_ms += elapsed_ms;
4908 
4909         start_sec = os::elapsedTime();
4910         non_young = true;
4911       }
4912     }
4913 
4914     rs_lengths += cur->rem_set()->occupied_locked();
4915 
4916     HeapRegion* next = cur->next_in_collection_set();
4917     assert(cur->in_collection_set(), "bad CS");
4918     cur->set_next_in_collection_set(NULL);
4919     clear_in_cset(cur);
4920 
4921     if (cur->is_young()) {
4922       int index = cur->young_index_in_cset();
4923       assert(index != -1, "invariant");
4924       assert((uint) index < collection_set()->young_region_length(), "invariant");
4925       size_t words_survived = surviving_young_words[index];
4926       cur->record_surv_words_in_group(words_survived);
4927 
4928       // At this point the we have 'popped' cur from the collection set
4929       // (linked via next_in_collection_set()) but it is still in the
4930       // young list (linked via next_young_region()). Clear the
4931       // _next_young_region field.
4932       cur->set_next_young_region(NULL);
4933     } else {
4934       int index = cur->young_index_in_cset();
4935       assert(index == -1, "invariant");
4936     }
4937 
4938     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4939             (!cur->is_young() && cur->young_index_in_cset() == -1),
4940             "invariant" );
4941 
4942     if (!cur->evacuation_failed()) {
4943       MemRegion used_mr = cur->used_region();
4944 
4945       // And the region is empty.
4946       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
4947       pre_used += cur->used();
4948       free_region(cur, &local_free_list, false /* par */, true /* locked */);
4949     } else {
4950       cur->uninstall_surv_rate_group();
4951       if (cur->is_young()) {
4952         cur->set_young_index_in_cset(-1);
4953       }
4954       cur->set_evacuation_failed(false);
4955       // When moving a young gen region to old gen, we "allocate" that whole region
4956       // there. This is in addition to any already evacuated objects. Notify the
4957       // policy about that.
4958       // Old gen regions do not cause an additional allocation: both the objects
4959       // still in the region and the ones already moved are accounted for elsewhere.
4960       if (cur->is_young()) {
4961         policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
4962       }
4963       // The region is now considered to be old.
4964       cur->set_old();
4965       // Do some allocation statistics accounting. Regions that failed evacuation
4966       // are always made old, so there is no need to update anything in the young
4967       // gen statistics, but we need to update old gen statistics.
4968       size_t used_words = cur->marked_bytes() / HeapWordSize;
4969       _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
4970       _old_set.add(cur);
4971       evacuation_info.increment_collectionset_used_after(cur->used());
4972     }
4973     cur = next;
4974   }
4975 
4976   evacuation_info.set_regions_freed(local_free_list.length());
4977   policy->record_max_rs_lengths(rs_lengths);
4978   policy->cset_regions_freed();
4979 
4980   double end_sec = os::elapsedTime();
4981   double elapsed_ms = (end_sec - start_sec) * 1000.0;
4982 
4983   if (non_young) {
4984     non_young_time_ms += elapsed_ms;
4985   } else {
4986     young_time_ms += elapsed_ms;
4987   }
4988 
4989   prepend_to_freelist(&local_free_list);
4990   decrement_summary_bytes(pre_used);
4991   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
4992   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
4993 }
4994 
4995 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4996  private:
4997   FreeRegionList* _free_region_list;
4998   HeapRegionSet* _proxy_set;
4999   uint _humongous_regions_removed;
5000   size_t _freed_bytes;
5001  public:
5002 
5003   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5004     _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
5005   }
5006 
5007   virtual bool doHeapRegion(HeapRegion* r) {
5008     if (!r->is_starts_humongous()) {
5009       return false;
5010     }
5011 
5012     G1CollectedHeap* g1h = G1CollectedHeap::heap();
5013 
5014     oop obj = (oop)r->bottom();
5015     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5016 
5017     // The following checks whether the humongous object is live are sufficient.
5018     // The main additional check (in addition to having a reference from the roots
5019     // or the young gen) is whether the humongous object has a remembered set entry.
5020     //
5021     // A humongous object cannot be live if there is no remembered set for it
5022     // because:
5023     // - there can be no references from within humongous starts regions referencing
5024     // the object because we never allocate other objects into them.
5025     // (I.e. there are no intra-region references that may be missed by the
5026     // remembered set)
5027     // - as soon there is a remembered set entry to the humongous starts region
5028     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5029     // until the end of a concurrent mark.
5030     //
5031     // It is not required to check whether the object has been found dead by marking
5032     // or not, in fact it would prevent reclamation within a concurrent cycle, as
5033     // all objects allocated during that time are considered live.
5034     // SATB marking is even more conservative than the remembered set.
5035     // So if at this point in the collection there is no remembered set entry,
5036     // nobody has a reference to it.
5037     // At the start of collection we flush all refinement logs, and remembered sets
5038     // are completely up-to-date wrt to references to the humongous object.
5039     //
5040     // Other implementation considerations:
5041     // - never consider object arrays at this time because they would pose
5042     // considerable effort for cleaning up the the remembered sets. This is
5043     // required because stale remembered sets might reference locations that
5044     // are currently allocated into.
5045     uint region_idx = r->hrm_index();
5046     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5047         !r->rem_set()->is_empty()) {
5048       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",
5049                                region_idx,
5050                                (size_t)obj->size() * HeapWordSize,
5051                                p2i(r->bottom()),
5052                                r->rem_set()->occupied(),
5053                                r->rem_set()->strong_code_roots_list_length(),
5054                                next_bitmap->isMarked(r->bottom()),
5055                                g1h->is_humongous_reclaim_candidate(region_idx),
5056                                obj->is_typeArray()
5057                               );
5058       return false;
5059     }
5060 
5061     guarantee(obj->is_typeArray(),
5062               "Only eagerly reclaiming type arrays is supported, but the object "
5063               PTR_FORMAT " is not.", p2i(r->bottom()));
5064 
5065     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",
5066                              region_idx,
5067                              (size_t)obj->size() * HeapWordSize,
5068                              p2i(r->bottom()),
5069                              r->rem_set()->occupied(),
5070                              r->rem_set()->strong_code_roots_list_length(),
5071                              next_bitmap->isMarked(r->bottom()),
5072                              g1h->is_humongous_reclaim_candidate(region_idx),
5073                              obj->is_typeArray()
5074                             );
5075 
5076     // Need to clear mark bit of the humongous object if already set.
5077     if (next_bitmap->isMarked(r->bottom())) {
5078       next_bitmap->clear(r->bottom());
5079     }
5080     do {
5081       HeapRegion* next = g1h->next_region_in_humongous(r);
5082       _freed_bytes += r->used();
5083       r->set_containing_set(NULL);
5084       _humongous_regions_removed++;
5085       g1h->free_humongous_region(r, _free_region_list, false);
5086       r = next;
5087     } while (r != NULL);
5088 
5089     return false;
5090   }
5091 
5092   uint humongous_free_count() {
5093     return _humongous_regions_removed;
5094   }
5095 
5096   size_t bytes_freed() const {
5097     return _freed_bytes;
5098   }
5099 };
5100 
5101 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5102   assert_at_safepoint(true);
5103 
5104   if (!G1EagerReclaimHumongousObjects ||
5105       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5106     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5107     return;
5108   }
5109 
5110   double start_time = os::elapsedTime();
5111 
5112   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5113 
5114   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5115   heap_region_iterate(&cl);
5116 
5117   remove_from_old_sets(0, cl.humongous_free_count());
5118 
5119   G1HRPrinter* hrp = hr_printer();
5120   if (hrp->is_active()) {
5121     FreeRegionListIterator iter(&local_cleanup_list);
5122     while (iter.more_available()) {
5123       HeapRegion* hr = iter.get_next();
5124       hrp->cleanup(hr);
5125     }
5126   }
5127 
5128   prepend_to_freelist(&local_cleanup_list);
5129   decrement_summary_bytes(cl.bytes_freed());
5130 
5131   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5132                                                                     cl.humongous_free_count());
5133 }
5134 
5135 // This routine is similar to the above but does not record
5136 // any policy statistics or update free lists; we are abandoning
5137 // the current incremental collection set in preparation of a
5138 // full collection. After the full GC we will start to build up
5139 // the incremental collection set again.
5140 // This is only called when we're doing a full collection
5141 // and is immediately followed by the tearing down of the young list.
5142 
5143 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5144   HeapRegion* cur = cs_head;
5145 
5146   while (cur != NULL) {
5147     HeapRegion* next = cur->next_in_collection_set();
5148     assert(cur->in_collection_set(), "bad CS");
5149     cur->set_next_in_collection_set(NULL);
5150     clear_in_cset(cur);
5151     cur->set_young_index_in_cset(-1);
5152     cur = next;
5153   }
5154 }
5155 
5156 void G1CollectedHeap::set_free_regions_coming() {
5157   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5158 
5159   assert(!free_regions_coming(), "pre-condition");
5160   _free_regions_coming = true;
5161 }
5162 
5163 void G1CollectedHeap::reset_free_regions_coming() {
5164   assert(free_regions_coming(), "pre-condition");
5165 
5166   {
5167     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5168     _free_regions_coming = false;
5169     SecondaryFreeList_lock->notify_all();
5170   }
5171 
5172   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5173 }
5174 
5175 void G1CollectedHeap::wait_while_free_regions_coming() {
5176   // Most of the time we won't have to wait, so let's do a quick test
5177   // first before we take the lock.
5178   if (!free_regions_coming()) {
5179     return;
5180   }
5181 
5182   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5183 
5184   {
5185     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5186     while (free_regions_coming()) {
5187       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5188     }
5189   }
5190 
5191   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5192 }
5193 
5194 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5195   return _allocator->is_retained_old_region(hr);
5196 }
5197 
5198 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5199   _young_list->push_region(hr);
5200 }
5201 
5202 class NoYoungRegionsClosure: public HeapRegionClosure {
5203 private:
5204   bool _success;
5205 public:
5206   NoYoungRegionsClosure() : _success(true) { }
5207   bool doHeapRegion(HeapRegion* r) {
5208     if (r->is_young()) {
5209       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5210                             p2i(r->bottom()), p2i(r->end()));
5211       _success = false;
5212     }
5213     return false;
5214   }
5215   bool success() { return _success; }
5216 };
5217 
5218 bool G1CollectedHeap::check_young_list_empty(bool check_heap) {
5219   bool ret = _young_list->check_list_empty();
5220 
5221   if (check_heap) {
5222     NoYoungRegionsClosure closure;
5223     heap_region_iterate(&closure);
5224     ret = ret && closure.success();
5225   }
5226 
5227   return ret;
5228 }
5229 
5230 class TearDownRegionSetsClosure : public HeapRegionClosure {
5231 private:
5232   HeapRegionSet *_old_set;
5233 
5234 public:
5235   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5236 
5237   bool doHeapRegion(HeapRegion* r) {
5238     if (r->is_old()) {
5239       _old_set->remove(r);
5240     } else {
5241       // We ignore free regions, we'll empty the free list afterwards.
5242       // We ignore young regions, we'll empty the young list afterwards.
5243       // We ignore humongous regions, we're not tearing down the
5244       // humongous regions set.
5245       assert(r->is_free() || r->is_young() || r->is_humongous(),
5246              "it cannot be another type");
5247     }
5248     return false;
5249   }
5250 
5251   ~TearDownRegionSetsClosure() {
5252     assert(_old_set->is_empty(), "post-condition");
5253   }
5254 };
5255 
5256 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5257   assert_at_safepoint(true /* should_be_vm_thread */);
5258 
5259   if (!free_list_only) {
5260     TearDownRegionSetsClosure cl(&_old_set);
5261     heap_region_iterate(&cl);
5262 
5263     // Note that emptying the _young_list is postponed and instead done as
5264     // the first step when rebuilding the regions sets again. The reason for
5265     // this is that during a full GC string deduplication needs to know if
5266     // a collected region was young or old when the full GC was initiated.
5267   }
5268   _hrm.remove_all_free_regions();
5269 }
5270 
5271 void G1CollectedHeap::increase_used(size_t bytes) {
5272   _summary_bytes_used += bytes;
5273 }
5274 
5275 void G1CollectedHeap::decrease_used(size_t bytes) {
5276   assert(_summary_bytes_used >= bytes,
5277          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5278          _summary_bytes_used, bytes);
5279   _summary_bytes_used -= bytes;
5280 }
5281 
5282 void G1CollectedHeap::set_used(size_t bytes) {
5283   _summary_bytes_used = bytes;
5284 }
5285 
5286 class RebuildRegionSetsClosure : public HeapRegionClosure {
5287 private:
5288   bool            _free_list_only;
5289   HeapRegionSet*   _old_set;
5290   HeapRegionManager*   _hrm;
5291   size_t          _total_used;
5292 
5293 public:
5294   RebuildRegionSetsClosure(bool free_list_only,
5295                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5296     _free_list_only(free_list_only),
5297     _old_set(old_set), _hrm(hrm), _total_used(0) {
5298     assert(_hrm->num_free_regions() == 0, "pre-condition");
5299     if (!free_list_only) {
5300       assert(_old_set->is_empty(), "pre-condition");
5301     }
5302   }
5303 
5304   bool doHeapRegion(HeapRegion* r) {
5305     if (r->is_empty()) {
5306       // Add free regions to the free list
5307       r->set_free();
5308       r->set_allocation_context(AllocationContext::system());
5309       _hrm->insert_into_free_list(r);
5310     } else if (!_free_list_only) {
5311       assert(!r->is_young(), "we should not come across young regions");
5312 
5313       if (r->is_humongous()) {
5314         // We ignore humongous regions. We left the humongous set unchanged.
5315       } else {
5316         // Objects that were compacted would have ended up on regions
5317         // that were previously old or free.  Archive regions (which are
5318         // old) will not have been touched.
5319         assert(r->is_free() || r->is_old(), "invariant");
5320         // We now consider them old, so register as such. Leave
5321         // archive regions set that way, however, while still adding
5322         // them to the old set.
5323         if (!r->is_archive()) {
5324           r->set_old();
5325         }
5326         _old_set->add(r);
5327       }
5328       _total_used += r->used();
5329     }
5330 
5331     return false;
5332   }
5333 
5334   size_t total_used() {
5335     return _total_used;
5336   }
5337 };
5338 
5339 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5340   assert_at_safepoint(true /* should_be_vm_thread */);
5341 
5342   if (!free_list_only) {
5343     _young_list->empty_list();
5344   }
5345 
5346   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5347   heap_region_iterate(&cl);
5348 
5349   if (!free_list_only) {
5350     set_used(cl.total_used());
5351     if (_archive_allocator != NULL) {
5352       _archive_allocator->clear_used();
5353     }
5354   }
5355   assert(used_unlocked() == recalculate_used(),
5356          "inconsistent used_unlocked(), "
5357          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5358          used_unlocked(), recalculate_used());
5359 }
5360 
5361 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5362   _refine_cte_cl->set_concurrent(concurrent);
5363 }
5364 
5365 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5366   HeapRegion* hr = heap_region_containing(p);
5367   return hr->is_in(p);
5368 }
5369 
5370 // Methods for the mutator alloc region
5371 
5372 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5373                                                       bool force) {
5374   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5375   assert(!force || g1_policy()->can_expand_young_list(),
5376          "if force is true we should be able to expand the young list");
5377   bool young_list_full = g1_policy()->is_young_list_full();
5378   if (force || !young_list_full) {
5379     HeapRegion* new_alloc_region = new_region(word_size,
5380                                               false /* is_old */,
5381                                               false /* do_expand */);
5382     if (new_alloc_region != NULL) {
5383       set_region_short_lived_locked(new_alloc_region);
5384       _hr_printer.alloc(new_alloc_region, young_list_full);
5385       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5386       return new_alloc_region;
5387     }
5388   }
5389   return NULL;
5390 }
5391 
5392 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5393                                                   size_t allocated_bytes) {
5394   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5395   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5396 
5397   collection_set()->add_eden_region(alloc_region);
5398   increase_used(allocated_bytes);
5399   _hr_printer.retire(alloc_region);
5400   // We update the eden sizes here, when the region is retired,
5401   // instead of when it's allocated, since this is the point that its
5402   // used space has been recored in _summary_bytes_used.
5403   g1mm()->update_eden_size();
5404 }
5405 
5406 // Methods for the GC alloc regions
5407 
5408 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
5409                                                  uint count,
5410                                                  InCSetState dest) {
5411   assert(FreeList_lock->owned_by_self(), "pre-condition");
5412 
5413   if (count < g1_policy()->max_regions(dest)) {
5414     const bool is_survivor = (dest.is_young());
5415     HeapRegion* new_alloc_region = new_region(word_size,
5416                                               !is_survivor,
5417                                               true /* do_expand */);
5418     if (new_alloc_region != NULL) {
5419       // We really only need to do this for old regions given that we
5420       // should never scan survivors. But it doesn't hurt to do it
5421       // for survivors too.
5422       new_alloc_region->record_timestamp();
5423       if (is_survivor) {
5424         new_alloc_region->set_survivor();
5425         _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5426       } else {
5427         new_alloc_region->set_old();
5428         _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5429       }
5430       _hr_printer.alloc(new_alloc_region);
5431       bool during_im = collector_state()->during_initial_mark_pause();
5432       new_alloc_region->note_start_of_copying(during_im);
5433       return new_alloc_region;
5434     }
5435   }
5436   return NULL;
5437 }
5438 
5439 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5440                                              size_t allocated_bytes,
5441                                              InCSetState dest) {
5442   bool during_im = collector_state()->during_initial_mark_pause();
5443   alloc_region->note_end_of_copying(during_im);
5444   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5445   if (dest.is_young()) {
5446     young_list()->add_survivor_region(alloc_region);
5447   } else {
5448     _old_set.add(alloc_region);
5449   }
5450   _hr_printer.retire(alloc_region);
5451 }
5452 
5453 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5454   bool expanded = false;
5455   uint index = _hrm.find_highest_free(&expanded);
5456 
5457   if (index != G1_NO_HRM_INDEX) {
5458     if (expanded) {
5459       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5460                                 HeapRegion::GrainWords * HeapWordSize);
5461     }
5462     _hrm.allocate_free_regions_starting_at(index, 1);
5463     return region_at(index);
5464   }
5465   return NULL;
5466 }
5467 
5468 // Optimized nmethod scanning
5469 
5470 class RegisterNMethodOopClosure: public OopClosure {
5471   G1CollectedHeap* _g1h;
5472   nmethod* _nm;
5473 
5474   template <class T> void do_oop_work(T* p) {
5475     T heap_oop = oopDesc::load_heap_oop(p);
5476     if (!oopDesc::is_null(heap_oop)) {
5477       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5478       HeapRegion* hr = _g1h->heap_region_containing(obj);
5479       assert(!hr->is_continues_humongous(),
5480              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5481              " starting at " HR_FORMAT,
5482              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5483 
5484       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5485       hr->add_strong_code_root_locked(_nm);
5486     }
5487   }
5488 
5489 public:
5490   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5491     _g1h(g1h), _nm(nm) {}
5492 
5493   void do_oop(oop* p)       { do_oop_work(p); }
5494   void do_oop(narrowOop* p) { do_oop_work(p); }
5495 };
5496 
5497 class UnregisterNMethodOopClosure: public OopClosure {
5498   G1CollectedHeap* _g1h;
5499   nmethod* _nm;
5500 
5501   template <class T> void do_oop_work(T* p) {
5502     T heap_oop = oopDesc::load_heap_oop(p);
5503     if (!oopDesc::is_null(heap_oop)) {
5504       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5505       HeapRegion* hr = _g1h->heap_region_containing(obj);
5506       assert(!hr->is_continues_humongous(),
5507              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5508              " starting at " HR_FORMAT,
5509              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5510 
5511       hr->remove_strong_code_root(_nm);
5512     }
5513   }
5514 
5515 public:
5516   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5517     _g1h(g1h), _nm(nm) {}
5518 
5519   void do_oop(oop* p)       { do_oop_work(p); }
5520   void do_oop(narrowOop* p) { do_oop_work(p); }
5521 };
5522 
5523 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5524   CollectedHeap::register_nmethod(nm);
5525 
5526   guarantee(nm != NULL, "sanity");
5527   RegisterNMethodOopClosure reg_cl(this, nm);
5528   nm->oops_do(&reg_cl);
5529 }
5530 
5531 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5532   CollectedHeap::unregister_nmethod(nm);
5533 
5534   guarantee(nm != NULL, "sanity");
5535   UnregisterNMethodOopClosure reg_cl(this, nm);
5536   nm->oops_do(&reg_cl, true);
5537 }
5538 
5539 void G1CollectedHeap::purge_code_root_memory() {
5540   double purge_start = os::elapsedTime();
5541   G1CodeRootSet::purge();
5542   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5543   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5544 }
5545 
5546 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5547   G1CollectedHeap* _g1h;
5548 
5549 public:
5550   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5551     _g1h(g1h) {}
5552 
5553   void do_code_blob(CodeBlob* cb) {
5554     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5555     if (nm == NULL) {
5556       return;
5557     }
5558 
5559     if (ScavengeRootsInCode) {
5560       _g1h->register_nmethod(nm);
5561     }
5562   }
5563 };
5564 
5565 void G1CollectedHeap::rebuild_strong_code_roots() {
5566   RebuildStrongCodeRootClosure blob_cl(this);
5567   CodeCache::blobs_do(&blob_cl);
5568 }
--- EOF ---