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       warning("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       warning("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       warning("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   trace_heap_before_gc(gc_tracer);
1233 
1234   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1235 
1236   _verifier->verify_region_sets_optional();
1237 
1238   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1239                            collector_policy()->should_clear_all_soft_refs();
1240 
1241   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1242 
1243   {
1244     IsGCActiveMark x;
1245 
1246     // Timing
1247     assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1248     GCTraceCPUTime tcpu;
1249 
1250     {
1251       GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1252       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1253       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1254 
1255       G1HeapTransition heap_transition(this);
1256       g1_policy()->record_full_collection_start();
1257 
1258       // Note: When we have a more flexible GC logging framework that
1259       // allows us to add optional attributes to a GC log record we
1260       // could consider timing and reporting how long we wait in the
1261       // following two methods.
1262       wait_while_free_regions_coming();
1263       // If we start the compaction before the CM threads finish
1264       // scanning the root regions we might trip them over as we'll
1265       // be moving objects / updating references. So let's wait until
1266       // they are done. By telling them to abort, they should complete
1267       // early.
1268       _cm->root_regions()->abort();
1269       _cm->root_regions()->wait_until_scan_finished();
1270       append_secondary_free_list_if_not_empty_with_lock();
1271 
1272       gc_prologue(true);
1273       increment_total_collections(true /* full gc */);
1274       increment_old_marking_cycles_started();
1275 
1276       assert(used() == recalculate_used(), "Should be equal");
1277 
1278       _verifier->verify_before_gc();
1279 
1280       _verifier->check_bitmaps("Full GC Start");
1281       pre_full_gc_dump(gc_timer);
1282 
1283 #if defined(COMPILER2) || INCLUDE_JVMCI
1284       DerivedPointerTable::clear();
1285 #endif
1286 
1287       // Disable discovery and empty the discovered lists
1288       // for the CM ref processor.
1289       ref_processor_cm()->disable_discovery();
1290       ref_processor_cm()->abandon_partial_discovery();
1291       ref_processor_cm()->verify_no_references_recorded();
1292 
1293       // Abandon current iterations of concurrent marking and concurrent
1294       // refinement, if any are in progress.
1295       concurrent_mark()->abort();
1296 
1297       // Make sure we'll choose a new allocation region afterwards.
1298       _allocator->release_mutator_alloc_region();
1299       _allocator->abandon_gc_alloc_regions();
1300       g1_rem_set()->cleanupHRRS();
1301 
1302       // We may have added regions to the current incremental collection
1303       // set between the last GC or pause and now. We need to clear the
1304       // incremental collection set and then start rebuilding it afresh
1305       // after this full GC.
1306       abandon_collection_set(collection_set()->inc_head());
1307       collection_set()->clear_incremental();
1308       collection_set()->stop_incremental_building();
1309 
1310       tear_down_region_sets(false /* free_list_only */);
1311       collector_state()->set_gcs_are_young(true);
1312 
1313       // See the comments in g1CollectedHeap.hpp and
1314       // G1CollectedHeap::ref_processing_init() about
1315       // how reference processing currently works in G1.
1316 
1317       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1318       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1319 
1320       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1321       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1322 
1323       ref_processor_stw()->enable_discovery();
1324       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1325 
1326       // Do collection work
1327       {
1328         HandleMark hm;  // Discard invalid handles created during gc
1329         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1330       }
1331 
1332       assert(num_free_regions() == 0, "we should not have added any free regions");
1333       rebuild_region_sets(false /* free_list_only */);
1334 
1335       // Enqueue any discovered reference objects that have
1336       // not been removed from the discovered lists.
1337       ref_processor_stw()->enqueue_discovered_references();
1338 
1339 #if defined(COMPILER2) || INCLUDE_JVMCI
1340       DerivedPointerTable::update_pointers();
1341 #endif
1342 
1343       MemoryService::track_memory_usage();
1344 
1345       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1346       ref_processor_stw()->verify_no_references_recorded();
1347 
1348       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1349       ClassLoaderDataGraph::purge();
1350       MetaspaceAux::verify_metrics();
1351 
1352       // Note: since we've just done a full GC, concurrent
1353       // marking is no longer active. Therefore we need not
1354       // re-enable reference discovery for the CM ref processor.
1355       // That will be done at the start of the next marking cycle.
1356       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1357       ref_processor_cm()->verify_no_references_recorded();
1358 
1359       reset_gc_time_stamp();
1360       // Since everything potentially moved, we will clear all remembered
1361       // sets, and clear all cards.  Later we will rebuild remembered
1362       // sets. We will also reset the GC time stamps of the regions.
1363       clear_rsets_post_compaction();
1364       check_gc_time_stamps();
1365 
1366       resize_if_necessary_after_full_collection();
1367 
1368       // We should do this after we potentially resize the heap so
1369       // that all the COMMIT / UNCOMMIT events are generated before
1370       // the compaction events.
1371       print_hrm_post_compaction();
1372 
1373       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1374       if (hot_card_cache->use_cache()) {
1375         hot_card_cache->reset_card_counts();
1376         hot_card_cache->reset_hot_cache();
1377       }
1378 
1379       // Rebuild remembered sets of all regions.
1380       uint n_workers =
1381         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1382                                                 workers()->active_workers(),
1383                                                 Threads::number_of_non_daemon_threads());
1384       workers()->set_active_workers(n_workers);
1385 
1386       ParRebuildRSTask rebuild_rs_task(this);
1387       workers()->run_task(&rebuild_rs_task);
1388 
1389       // Rebuild the strong code root lists for each region
1390       rebuild_strong_code_roots();
1391 
1392       if (true) { // FIXME
1393         MetaspaceGC::compute_new_size();
1394       }
1395 
1396 #ifdef TRACESPINNING
1397       ParallelTaskTerminator::print_termination_counts();
1398 #endif
1399 
1400       // Discard all rset updates
1401       JavaThread::dirty_card_queue_set().abandon_logs();
1402       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1403 
1404       // At this point there should be no regions in the
1405       // entire heap tagged as young.
1406       assert(check_young_list_empty(true /* check_heap */),
1407              "young list should be empty at this point");
1408 
1409       // Update the number of full collections that have been completed.
1410       increment_old_marking_cycles_completed(false /* concurrent */);
1411 
1412       _hrm.verify_optional();
1413       _verifier->verify_region_sets_optional();
1414 
1415       _verifier->verify_after_gc();
1416 
1417       // Clear the previous marking bitmap, if needed for bitmap verification.
1418       // Note we cannot do this when we clear the next marking bitmap in
1419       // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1420       // objects marked during a full GC against the previous bitmap.
1421       // But we need to clear it before calling check_bitmaps below since
1422       // the full GC has compacted objects and updated TAMS but not updated
1423       // the prev bitmap.
1424       if (G1VerifyBitmaps) {
1425         ((G1CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1426       }
1427       _verifier->check_bitmaps("Full GC End");
1428 
1429       // Start a new incremental collection set for the next pause
1430       assert(collection_set()->head() == NULL, "must be");
1431       collection_set()->start_incremental_building();
1432 
1433       clear_cset_fast_test();
1434 
1435       _allocator->init_mutator_alloc_region();
1436 
1437       g1_policy()->record_full_collection_end();
1438 
1439       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1440       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1441       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1442       // before any GC notifications are raised.
1443       g1mm()->update_sizes();
1444 
1445       gc_epilogue(true);
1446 
1447       heap_transition.print();
1448 
1449       print_heap_after_gc();
1450       trace_heap_after_gc(gc_tracer);
1451 
1452       post_full_gc_dump(gc_timer);
1453     }
1454 
1455     gc_timer->register_gc_end();
1456     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1457   }
1458 
1459   return true;
1460 }
1461 
1462 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1463   // Currently, there is no facility in the do_full_collection(bool) API to notify
1464   // the caller that the collection did not succeed (e.g., because it was locked
1465   // out by the GC locker). So, right now, we'll ignore the return value.
1466   bool dummy = do_full_collection(true,                /* explicit_gc */
1467                                   clear_all_soft_refs);
1468 }
1469 
1470 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1471   // Include bytes that will be pre-allocated to support collections, as "used".
1472   const size_t used_after_gc = used();
1473   const size_t capacity_after_gc = capacity();
1474   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1475 
1476   // This is enforced in arguments.cpp.
1477   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1478          "otherwise the code below doesn't make sense");
1479 
1480   // We don't have floating point command-line arguments
1481   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1482   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1483   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1484   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1485 
1486   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1487   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1488 
1489   // We have to be careful here as these two calculations can overflow
1490   // 32-bit size_t's.
1491   double used_after_gc_d = (double) used_after_gc;
1492   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1493   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1494 
1495   // Let's make sure that they are both under the max heap size, which
1496   // by default will make them fit into a size_t.
1497   double desired_capacity_upper_bound = (double) max_heap_size;
1498   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1499                                     desired_capacity_upper_bound);
1500   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1501                                     desired_capacity_upper_bound);
1502 
1503   // We can now safely turn them into size_t's.
1504   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1505   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1506 
1507   // This assert only makes sense here, before we adjust them
1508   // with respect to the min and max heap size.
1509   assert(minimum_desired_capacity <= maximum_desired_capacity,
1510          "minimum_desired_capacity = " SIZE_FORMAT ", "
1511          "maximum_desired_capacity = " SIZE_FORMAT,
1512          minimum_desired_capacity, maximum_desired_capacity);
1513 
1514   // Should not be greater than the heap max size. No need to adjust
1515   // it with respect to the heap min size as it's a lower bound (i.e.,
1516   // we'll try to make the capacity larger than it, not smaller).
1517   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1518   // Should not be less than the heap min size. No need to adjust it
1519   // with respect to the heap max size as it's an upper bound (i.e.,
1520   // we'll try to make the capacity smaller than it, not greater).
1521   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1522 
1523   if (capacity_after_gc < minimum_desired_capacity) {
1524     // Don't expand unless it's significant
1525     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1526 
1527     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1528                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1529                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1530 
1531     expand(expand_bytes);
1532 
1533     // No expansion, now see if we want to shrink
1534   } else if (capacity_after_gc > maximum_desired_capacity) {
1535     // Capacity too large, compute shrinking size
1536     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1537 
1538     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1539                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1540                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1541 
1542     shrink(shrink_bytes);
1543   }
1544 }
1545 
1546 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1547                                                             AllocationContext_t context,
1548                                                             bool do_gc,
1549                                                             bool clear_all_soft_refs,
1550                                                             bool expect_null_mutator_alloc_region,
1551                                                             bool* gc_succeeded) {
1552   *gc_succeeded = true;
1553   // Let's attempt the allocation first.
1554   HeapWord* result =
1555     attempt_allocation_at_safepoint(word_size,
1556                                     context,
1557                                     expect_null_mutator_alloc_region);
1558   if (result != NULL) {
1559     assert(*gc_succeeded, "sanity");
1560     return result;
1561   }
1562 
1563   // In a G1 heap, we're supposed to keep allocation from failing by
1564   // incremental pauses.  Therefore, at least for now, we'll favor
1565   // expansion over collection.  (This might change in the future if we can
1566   // do something smarter than full collection to satisfy a failed alloc.)
1567   result = expand_and_allocate(word_size, context);
1568   if (result != NULL) {
1569     assert(*gc_succeeded, "sanity");
1570     return result;
1571   }
1572 
1573   if (do_gc) {
1574     // Expansion didn't work, we'll try to do a Full GC.
1575     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1576                                        clear_all_soft_refs);
1577   }
1578 
1579   return NULL;
1580 }
1581 
1582 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1583                                                      AllocationContext_t context,
1584                                                      bool* succeeded) {
1585   assert_at_safepoint(true /* should_be_vm_thread */);
1586 
1587   // Attempts to allocate followed by Full GC.
1588   HeapWord* result =
1589     satisfy_failed_allocation_helper(word_size,
1590                                      context,
1591                                      true,  /* do_gc */
1592                                      false, /* clear_all_soft_refs */
1593                                      false, /* expect_null_mutator_alloc_region */
1594                                      succeeded);
1595 
1596   if (result != NULL || !*succeeded) {
1597     return result;
1598   }
1599 
1600   // Attempts to allocate followed by Full GC that will collect all soft references.
1601   result = satisfy_failed_allocation_helper(word_size,
1602                                             context,
1603                                             true, /* do_gc */
1604                                             true, /* clear_all_soft_refs */
1605                                             true, /* expect_null_mutator_alloc_region */
1606                                             succeeded);
1607 
1608   if (result != NULL || !*succeeded) {
1609     return result;
1610   }
1611 
1612   // Attempts to allocate, no GC
1613   result = satisfy_failed_allocation_helper(word_size,
1614                                             context,
1615                                             false, /* do_gc */
1616                                             false, /* clear_all_soft_refs */
1617                                             true,  /* expect_null_mutator_alloc_region */
1618                                             succeeded);
1619 
1620   if (result != NULL) {
1621     assert(*succeeded, "sanity");
1622     return result;
1623   }
1624 
1625   assert(!collector_policy()->should_clear_all_soft_refs(),
1626          "Flag should have been handled and cleared prior to this point");
1627 
1628   // What else?  We might try synchronous finalization later.  If the total
1629   // space available is large enough for the allocation, then a more
1630   // complete compaction phase than we've tried so far might be
1631   // appropriate.
1632   assert(*succeeded, "sanity");
1633   return NULL;
1634 }
1635 
1636 // Attempting to expand the heap sufficiently
1637 // to support an allocation of the given "word_size".  If
1638 // successful, perform the allocation and return the address of the
1639 // allocated block, or else "NULL".
1640 
1641 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1642   assert_at_safepoint(true /* should_be_vm_thread */);
1643 
1644   _verifier->verify_region_sets_optional();
1645 
1646   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1647   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1648                             word_size * HeapWordSize);
1649 
1650 
1651   if (expand(expand_bytes)) {
1652     _hrm.verify_optional();
1653     _verifier->verify_region_sets_optional();
1654     return attempt_allocation_at_safepoint(word_size,
1655                                            context,
1656                                            false /* expect_null_mutator_alloc_region */);
1657   }
1658   return NULL;
1659 }
1660 
1661 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1662   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1663   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1664                                        HeapRegion::GrainBytes);
1665 
1666   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1667                             expand_bytes, aligned_expand_bytes);
1668 
1669   if (is_maximal_no_gc()) {
1670     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1671     return false;
1672   }
1673 
1674   double expand_heap_start_time_sec = os::elapsedTime();
1675   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1676   assert(regions_to_expand > 0, "Must expand by at least one region");
1677 
1678   uint expanded_by = _hrm.expand_by(regions_to_expand);
1679   if (expand_time_ms != NULL) {
1680     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1681   }
1682 
1683   if (expanded_by > 0) {
1684     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1685     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1686     g1_policy()->record_new_heap_size(num_regions());
1687   } else {
1688     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1689 
1690     // The expansion of the virtual storage space was unsuccessful.
1691     // Let's see if it was because we ran out of swap.
1692     if (G1ExitOnExpansionFailure &&
1693         _hrm.available() >= regions_to_expand) {
1694       // We had head room...
1695       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1696     }
1697   }
1698   return regions_to_expand > 0;
1699 }
1700 
1701 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1702   size_t aligned_shrink_bytes =
1703     ReservedSpace::page_align_size_down(shrink_bytes);
1704   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1705                                          HeapRegion::GrainBytes);
1706   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1707 
1708   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1709   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1710 
1711 
1712   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",
1713                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1714   if (num_regions_removed > 0) {
1715     g1_policy()->record_new_heap_size(num_regions());
1716   } else {
1717     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1718   }
1719 }
1720 
1721 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1722   _verifier->verify_region_sets_optional();
1723 
1724   // We should only reach here at the end of a Full GC which means we
1725   // should not not be holding to any GC alloc regions. The method
1726   // below will make sure of that and do any remaining clean up.
1727   _allocator->abandon_gc_alloc_regions();
1728 
1729   // Instead of tearing down / rebuilding the free lists here, we
1730   // could instead use the remove_all_pending() method on free_list to
1731   // remove only the ones that we need to remove.
1732   tear_down_region_sets(true /* free_list_only */);
1733   shrink_helper(shrink_bytes);
1734   rebuild_region_sets(true /* free_list_only */);
1735 
1736   _hrm.verify_optional();
1737   _verifier->verify_region_sets_optional();
1738 }
1739 
1740 // Public methods.
1741 
1742 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1743   CollectedHeap(),
1744   _g1_policy(policy_),
1745   _collection_set(new G1CollectionSet(this, policy_)),
1746   _dirty_card_queue_set(false),
1747   _is_alive_closure_cm(this),
1748   _is_alive_closure_stw(this),
1749   _ref_processor_cm(NULL),
1750   _ref_processor_stw(NULL),
1751   _bot(NULL),
1752   _cg1r(NULL),
1753   _g1mm(NULL),
1754   _refine_cte_cl(NULL),
1755   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1756   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1757   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1758   _humongous_reclaim_candidates(),
1759   _has_humongous_reclaim_candidates(false),
1760   _archive_allocator(NULL),
1761   _free_regions_coming(false),
1762   _young_list(new YoungList(this)),
1763   _gc_time_stamp(0),
1764   _summary_bytes_used(0),
1765   _survivor_evac_stats(YoungPLABSize, PLABWeight),
1766   _old_evac_stats(OldPLABSize, PLABWeight),
1767   _expand_heap_after_alloc_failure(true),
1768   _old_marking_cycles_started(0),
1769   _old_marking_cycles_completed(0),
1770   _heap_summary_sent(false),
1771   _in_cset_fast_test(),
1772   _dirty_cards_region_list(NULL),
1773   _worker_cset_start_region(NULL),
1774   _worker_cset_start_region_time_stamp(NULL),
1775   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1776   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1777   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1778   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1779 
1780   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1781                           /* are_GC_task_threads */true,
1782                           /* are_ConcurrentGC_threads */false);
1783   _workers->initialize_workers();
1784   _verifier = new G1HeapVerifier(this);
1785 
1786   _allocator = G1Allocator::create_allocator(this);
1787   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1788 
1789   // Override the default _filler_array_max_size so that no humongous filler
1790   // objects are created.
1791   _filler_array_max_size = _humongous_object_threshold_in_words;
1792 
1793   uint n_queues = ParallelGCThreads;
1794   _task_queues = new RefToScanQueueSet(n_queues);
1795 
1796   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1797   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1798   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1799 
1800   for (uint i = 0; i < n_queues; i++) {
1801     RefToScanQueue* q = new RefToScanQueue();
1802     q->initialize();
1803     _task_queues->register_queue(i, q);
1804     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1805   }
1806   clear_cset_start_regions();
1807 
1808   // Initialize the G1EvacuationFailureALot counters and flags.
1809   NOT_PRODUCT(reset_evacuation_should_fail();)
1810 
1811   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1812 }
1813 
1814 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1815                                                                  size_t size,
1816                                                                  size_t translation_factor) {
1817   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1818   // Allocate a new reserved space, preferring to use large pages.
1819   ReservedSpace rs(size, preferred_page_size);
1820   G1RegionToSpaceMapper* result  =
1821     G1RegionToSpaceMapper::create_mapper(rs,
1822                                          size,
1823                                          rs.alignment(),
1824                                          HeapRegion::GrainBytes,
1825                                          translation_factor,
1826                                          mtGC);
1827   if (TracePageSizes) {
1828     tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1829                   description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1830   }
1831   return result;
1832 }
1833 
1834 jint G1CollectedHeap::initialize() {
1835   CollectedHeap::pre_initialize();
1836   os::enable_vtime();
1837 
1838   // Necessary to satisfy locking discipline assertions.
1839 
1840   MutexLocker x(Heap_lock);
1841 
1842   // While there are no constraints in the GC code that HeapWordSize
1843   // be any particular value, there are multiple other areas in the
1844   // system which believe this to be true (e.g. oop->object_size in some
1845   // cases incorrectly returns the size in wordSize units rather than
1846   // HeapWordSize).
1847   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1848 
1849   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1850   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1851   size_t heap_alignment = collector_policy()->heap_alignment();
1852 
1853   // Ensure that the sizes are properly aligned.
1854   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1855   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1856   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1857 
1858   _refine_cte_cl = new RefineCardTableEntryClosure();
1859 
1860   jint ecode = JNI_OK;
1861   _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1862   if (_cg1r == NULL) {
1863     return ecode;
1864   }
1865 
1866   // Reserve the maximum.
1867 
1868   // When compressed oops are enabled, the preferred heap base
1869   // is calculated by subtracting the requested size from the
1870   // 32Gb boundary and using the result as the base address for
1871   // heap reservation. If the requested size is not aligned to
1872   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1873   // into the ReservedHeapSpace constructor) then the actual
1874   // base of the reserved heap may end up differing from the
1875   // address that was requested (i.e. the preferred heap base).
1876   // If this happens then we could end up using a non-optimal
1877   // compressed oops mode.
1878 
1879   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1880                                                  heap_alignment);
1881 
1882   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1883 
1884   // Create the barrier set for the entire reserved region.
1885   G1SATBCardTableLoggingModRefBS* bs
1886     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1887   bs->initialize();
1888   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1889   set_barrier_set(bs);
1890 
1891   // Also create a G1 rem set.
1892   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1893 
1894   // Carve out the G1 part of the heap.
1895   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1896   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1897   G1RegionToSpaceMapper* heap_storage =
1898     G1RegionToSpaceMapper::create_mapper(g1_rs,
1899                                          g1_rs.size(),
1900                                          page_size,
1901                                          HeapRegion::GrainBytes,
1902                                          1,
1903                                          mtJavaHeap);
1904   os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1905                        max_byte_size, page_size,
1906                        heap_rs.base(),
1907                        heap_rs.size());
1908   heap_storage->set_mapping_changed_listener(&_listener);
1909 
1910   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1911   G1RegionToSpaceMapper* bot_storage =
1912     create_aux_memory_mapper("Block offset table",
1913                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1914                              G1BlockOffsetTable::heap_map_factor());
1915 
1916   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1917   G1RegionToSpaceMapper* cardtable_storage =
1918     create_aux_memory_mapper("Card table",
1919                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1920                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1921 
1922   G1RegionToSpaceMapper* card_counts_storage =
1923     create_aux_memory_mapper("Card counts table",
1924                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1925                              G1CardCounts::heap_map_factor());
1926 
1927   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1928   G1RegionToSpaceMapper* prev_bitmap_storage =
1929     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1930   G1RegionToSpaceMapper* next_bitmap_storage =
1931     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1932 
1933   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1934   g1_barrier_set()->initialize(cardtable_storage);
1935    // Do later initialization work for concurrent refinement.
1936   _cg1r->init(card_counts_storage);
1937 
1938   // 6843694 - ensure that the maximum region index can fit
1939   // in the remembered set structures.
1940   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1941   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1942 
1943   G1RemSet::initialize(max_regions());
1944 
1945   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1946   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1947   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1948             "too many cards per region");
1949 
1950   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1951 
1952   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1953 
1954   {
1955     HeapWord* start = _hrm.reserved().start();
1956     HeapWord* end = _hrm.reserved().end();
1957     size_t granularity = HeapRegion::GrainBytes;
1958 
1959     _in_cset_fast_test.initialize(start, end, granularity);
1960     _humongous_reclaim_candidates.initialize(start, end, granularity);
1961   }
1962 
1963   // Create the G1ConcurrentMark data structure and thread.
1964   // (Must do this late, so that "max_regions" is defined.)
1965   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1966   if (_cm == NULL || !_cm->completed_initialization()) {
1967     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1968     return JNI_ENOMEM;
1969   }
1970   _cmThread = _cm->cmThread();
1971 
1972   // Now expand into the initial heap size.
1973   if (!expand(init_byte_size)) {
1974     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1975     return JNI_ENOMEM;
1976   }
1977 
1978   // Perform any initialization actions delegated to the policy.
1979   g1_policy()->init();
1980 
1981   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1982                                                SATB_Q_FL_lock,
1983                                                G1SATBProcessCompletedThreshold,
1984                                                Shared_SATB_Q_lock);
1985 
1986   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1987                                                 DirtyCardQ_CBL_mon,
1988                                                 DirtyCardQ_FL_lock,
1989                                                 concurrent_g1_refine()->yellow_zone(),
1990                                                 concurrent_g1_refine()->red_zone(),
1991                                                 Shared_DirtyCardQ_lock,
1992                                                 NULL,  // fl_owner
1993                                                 true); // init_free_ids
1994 
1995   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1996                                     DirtyCardQ_CBL_mon,
1997                                     DirtyCardQ_FL_lock,
1998                                     -1, // never trigger processing
1999                                     -1, // no limit on length
2000                                     Shared_DirtyCardQ_lock,
2001                                     &JavaThread::dirty_card_queue_set());
2002 
2003   // Here we allocate the dummy HeapRegion that is required by the
2004   // G1AllocRegion class.
2005   HeapRegion* dummy_region = _hrm.get_dummy_region();
2006 
2007   // We'll re-use the same region whether the alloc region will
2008   // require BOT updates or not and, if it doesn't, then a non-young
2009   // region will complain that it cannot support allocations without
2010   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2011   dummy_region->set_eden();
2012   // Make sure it's full.
2013   dummy_region->set_top(dummy_region->end());
2014   G1AllocRegion::setup(this, dummy_region);
2015 
2016   _allocator->init_mutator_alloc_region();
2017 
2018   // Do create of the monitoring and management support so that
2019   // values in the heap have been properly initialized.
2020   _g1mm = new G1MonitoringSupport(this);
2021 
2022   G1StringDedup::initialize();
2023 
2024   _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2025   for (uint i = 0; i < ParallelGCThreads; i++) {
2026     new (&_preserved_objs[i]) OopAndMarkOopStack();
2027   }
2028 
2029   return JNI_OK;
2030 }
2031 
2032 void G1CollectedHeap::stop() {
2033   // Stop all concurrent threads. We do this to make sure these threads
2034   // do not continue to execute and access resources (e.g. logging)
2035   // that are destroyed during shutdown.
2036   _cg1r->stop();
2037   _cmThread->stop();
2038   if (G1StringDedup::is_enabled()) {
2039     G1StringDedup::stop();
2040   }
2041 }
2042 
2043 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2044   return HeapRegion::max_region_size();
2045 }
2046 
2047 void G1CollectedHeap::post_initialize() {
2048   CollectedHeap::post_initialize();
2049   ref_processing_init();
2050 }
2051 
2052 void G1CollectedHeap::ref_processing_init() {
2053   // Reference processing in G1 currently works as follows:
2054   //
2055   // * There are two reference processor instances. One is
2056   //   used to record and process discovered references
2057   //   during concurrent marking; the other is used to
2058   //   record and process references during STW pauses
2059   //   (both full and incremental).
2060   // * Both ref processors need to 'span' the entire heap as
2061   //   the regions in the collection set may be dotted around.
2062   //
2063   // * For the concurrent marking ref processor:
2064   //   * Reference discovery is enabled at initial marking.
2065   //   * Reference discovery is disabled and the discovered
2066   //     references processed etc during remarking.
2067   //   * Reference discovery is MT (see below).
2068   //   * Reference discovery requires a barrier (see below).
2069   //   * Reference processing may or may not be MT
2070   //     (depending on the value of ParallelRefProcEnabled
2071   //     and ParallelGCThreads).
2072   //   * A full GC disables reference discovery by the CM
2073   //     ref processor and abandons any entries on it's
2074   //     discovered lists.
2075   //
2076   // * For the STW processor:
2077   //   * Non MT discovery is enabled at the start of a full GC.
2078   //   * Processing and enqueueing during a full GC is non-MT.
2079   //   * During a full GC, references are processed after marking.
2080   //
2081   //   * Discovery (may or may not be MT) is enabled at the start
2082   //     of an incremental evacuation pause.
2083   //   * References are processed near the end of a STW evacuation pause.
2084   //   * For both types of GC:
2085   //     * Discovery is atomic - i.e. not concurrent.
2086   //     * Reference discovery will not need a barrier.
2087 
2088   MemRegion mr = reserved_region();
2089 
2090   // Concurrent Mark ref processor
2091   _ref_processor_cm =
2092     new ReferenceProcessor(mr,    // span
2093                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2094                                 // mt processing
2095                            ParallelGCThreads,
2096                                 // degree of mt processing
2097                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2098                                 // mt discovery
2099                            MAX2(ParallelGCThreads, ConcGCThreads),
2100                                 // degree of mt discovery
2101                            false,
2102                                 // Reference discovery is not atomic
2103                            &_is_alive_closure_cm);
2104                                 // is alive closure
2105                                 // (for efficiency/performance)
2106 
2107   // STW ref processor
2108   _ref_processor_stw =
2109     new ReferenceProcessor(mr,    // span
2110                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2111                                 // mt processing
2112                            ParallelGCThreads,
2113                                 // degree of mt processing
2114                            (ParallelGCThreads > 1),
2115                                 // mt discovery
2116                            ParallelGCThreads,
2117                                 // degree of mt discovery
2118                            true,
2119                                 // Reference discovery is atomic
2120                            &_is_alive_closure_stw);
2121                                 // is alive closure
2122                                 // (for efficiency/performance)
2123 }
2124 
2125 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2126   return g1_policy();
2127 }
2128 
2129 size_t G1CollectedHeap::capacity() const {
2130   return _hrm.length() * HeapRegion::GrainBytes;
2131 }
2132 
2133 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2134   hr->reset_gc_time_stamp();
2135 }
2136 
2137 #ifndef PRODUCT
2138 
2139 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2140 private:
2141   unsigned _gc_time_stamp;
2142   bool _failures;
2143 
2144 public:
2145   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2146     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2147 
2148   virtual bool doHeapRegion(HeapRegion* hr) {
2149     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2150     if (_gc_time_stamp != region_gc_time_stamp) {
2151       log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2152                             region_gc_time_stamp, _gc_time_stamp);
2153       _failures = true;
2154     }
2155     return false;
2156   }
2157 
2158   bool failures() { return _failures; }
2159 };
2160 
2161 void G1CollectedHeap::check_gc_time_stamps() {
2162   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2163   heap_region_iterate(&cl);
2164   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2165 }
2166 #endif // PRODUCT
2167 
2168 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2169   _cg1r->hot_card_cache()->drain(cl, worker_i);
2170 }
2171 
2172 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2173   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2174   size_t n_completed_buffers = 0;
2175   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2176     n_completed_buffers++;
2177   }
2178   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2179   dcqs.clear_n_completed_buffers();
2180   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2181 }
2182 
2183 // Computes the sum of the storage used by the various regions.
2184 size_t G1CollectedHeap::used() const {
2185   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2186   if (_archive_allocator != NULL) {
2187     result += _archive_allocator->used();
2188   }
2189   return result;
2190 }
2191 
2192 size_t G1CollectedHeap::used_unlocked() const {
2193   return _summary_bytes_used;
2194 }
2195 
2196 class SumUsedClosure: public HeapRegionClosure {
2197   size_t _used;
2198 public:
2199   SumUsedClosure() : _used(0) {}
2200   bool doHeapRegion(HeapRegion* r) {
2201     _used += r->used();
2202     return false;
2203   }
2204   size_t result() { return _used; }
2205 };
2206 
2207 size_t G1CollectedHeap::recalculate_used() const {
2208   double recalculate_used_start = os::elapsedTime();
2209 
2210   SumUsedClosure blk;
2211   heap_region_iterate(&blk);
2212 
2213   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2214   return blk.result();
2215 }
2216 
2217 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2218   switch (cause) {
2219     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2220     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2221     case GCCause::_update_allocation_context_stats_inc: return true;
2222     case GCCause::_wb_conc_mark:                        return true;
2223     default :                                           return false;
2224   }
2225 }
2226 
2227 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2228   switch (cause) {
2229     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2230     case GCCause::_g1_humongous_allocation: return true;
2231     default:                                return is_user_requested_concurrent_full_gc(cause);
2232   }
2233 }
2234 
2235 #ifndef PRODUCT
2236 void G1CollectedHeap::allocate_dummy_regions() {
2237   // Let's fill up most of the region
2238   size_t word_size = HeapRegion::GrainWords - 1024;
2239   // And as a result the region we'll allocate will be humongous.
2240   guarantee(is_humongous(word_size), "sanity");
2241 
2242   // _filler_array_max_size is set to humongous object threshold
2243   // but temporarily change it to use CollectedHeap::fill_with_object().
2244   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2245 
2246   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2247     // Let's use the existing mechanism for the allocation
2248     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2249                                                  AllocationContext::system());
2250     if (dummy_obj != NULL) {
2251       MemRegion mr(dummy_obj, word_size);
2252       CollectedHeap::fill_with_object(mr);
2253     } else {
2254       // If we can't allocate once, we probably cannot allocate
2255       // again. Let's get out of the loop.
2256       break;
2257     }
2258   }
2259 }
2260 #endif // !PRODUCT
2261 
2262 void G1CollectedHeap::increment_old_marking_cycles_started() {
2263   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2264          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2265          "Wrong marking cycle count (started: %d, completed: %d)",
2266          _old_marking_cycles_started, _old_marking_cycles_completed);
2267 
2268   _old_marking_cycles_started++;
2269 }
2270 
2271 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2272   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2273 
2274   // We assume that if concurrent == true, then the caller is a
2275   // concurrent thread that was joined the Suspendible Thread
2276   // Set. If there's ever a cheap way to check this, we should add an
2277   // assert here.
2278 
2279   // Given that this method is called at the end of a Full GC or of a
2280   // concurrent cycle, and those can be nested (i.e., a Full GC can
2281   // interrupt a concurrent cycle), the number of full collections
2282   // completed should be either one (in the case where there was no
2283   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2284   // behind the number of full collections started.
2285 
2286   // This is the case for the inner caller, i.e. a Full GC.
2287   assert(concurrent ||
2288          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2289          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2290          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2291          "is inconsistent with _old_marking_cycles_completed = %u",
2292          _old_marking_cycles_started, _old_marking_cycles_completed);
2293 
2294   // This is the case for the outer caller, i.e. the concurrent cycle.
2295   assert(!concurrent ||
2296          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2297          "for outer caller (concurrent cycle): "
2298          "_old_marking_cycles_started = %u "
2299          "is inconsistent with _old_marking_cycles_completed = %u",
2300          _old_marking_cycles_started, _old_marking_cycles_completed);
2301 
2302   _old_marking_cycles_completed += 1;
2303 
2304   // We need to clear the "in_progress" flag in the CM thread before
2305   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2306   // is set) so that if a waiter requests another System.gc() it doesn't
2307   // incorrectly see that a marking cycle is still in progress.
2308   if (concurrent) {
2309     _cmThread->set_idle();
2310   }
2311 
2312   // This notify_all() will ensure that a thread that called
2313   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2314   // and it's waiting for a full GC to finish will be woken up. It is
2315   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2316   FullGCCount_lock->notify_all();
2317 }
2318 
2319 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2320   GCIdMarkAndRestore conc_gc_id_mark;
2321   collector_state()->set_concurrent_cycle_started(true);
2322   _gc_timer_cm->register_gc_start(start_time);
2323 
2324   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2325   trace_heap_before_gc(_gc_tracer_cm);
2326   _cmThread->set_gc_id(GCId::current());
2327 }
2328 
2329 void G1CollectedHeap::register_concurrent_cycle_end() {
2330   if (collector_state()->concurrent_cycle_started()) {
2331     GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2332     if (_cm->has_aborted()) {
2333       _gc_tracer_cm->report_concurrent_mode_failure();
2334     }
2335 
2336     _gc_timer_cm->register_gc_end();
2337     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2338 
2339     // Clear state variables to prepare for the next concurrent cycle.
2340     collector_state()->set_concurrent_cycle_started(false);
2341     _heap_summary_sent = false;
2342   }
2343 }
2344 
2345 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2346   if (collector_state()->concurrent_cycle_started()) {
2347     // This function can be called when:
2348     //  the cleanup pause is run
2349     //  the concurrent cycle is aborted before the cleanup pause.
2350     //  the concurrent cycle is aborted after the cleanup pause,
2351     //   but before the concurrent cycle end has been registered.
2352     // Make sure that we only send the heap information once.
2353     if (!_heap_summary_sent) {
2354       GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2355       trace_heap_after_gc(_gc_tracer_cm);
2356       _heap_summary_sent = true;
2357     }
2358   }
2359 }
2360 
2361 void G1CollectedHeap::collect(GCCause::Cause cause) {
2362   assert_heap_not_locked();
2363 
2364   uint gc_count_before;
2365   uint old_marking_count_before;
2366   uint full_gc_count_before;
2367   bool retry_gc;
2368 
2369   do {
2370     retry_gc = false;
2371 
2372     {
2373       MutexLocker ml(Heap_lock);
2374 
2375       // Read the GC count while holding the Heap_lock
2376       gc_count_before = total_collections();
2377       full_gc_count_before = total_full_collections();
2378       old_marking_count_before = _old_marking_cycles_started;
2379     }
2380 
2381     if (should_do_concurrent_full_gc(cause)) {
2382       // Schedule an initial-mark evacuation pause that will start a
2383       // concurrent cycle. We're setting word_size to 0 which means that
2384       // we are not requesting a post-GC allocation.
2385       VM_G1IncCollectionPause op(gc_count_before,
2386                                  0,     /* word_size */
2387                                  true,  /* should_initiate_conc_mark */
2388                                  g1_policy()->max_pause_time_ms(),
2389                                  cause);
2390       op.set_allocation_context(AllocationContext::current());
2391 
2392       VMThread::execute(&op);
2393       if (!op.pause_succeeded()) {
2394         if (old_marking_count_before == _old_marking_cycles_started) {
2395           retry_gc = op.should_retry_gc();
2396         } else {
2397           // A Full GC happened while we were trying to schedule the
2398           // initial-mark GC. No point in starting a new cycle given
2399           // that the whole heap was collected anyway.
2400         }
2401 
2402         if (retry_gc) {
2403           if (GCLocker::is_active_and_needs_gc()) {
2404             GCLocker::stall_until_clear();
2405           }
2406         }
2407       }
2408     } else {
2409       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2410           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2411 
2412         // Schedule a standard evacuation pause. We're setting word_size
2413         // to 0 which means that we are not requesting a post-GC allocation.
2414         VM_G1IncCollectionPause op(gc_count_before,
2415                                    0,     /* word_size */
2416                                    false, /* should_initiate_conc_mark */
2417                                    g1_policy()->max_pause_time_ms(),
2418                                    cause);
2419         VMThread::execute(&op);
2420       } else {
2421         // Schedule a Full GC.
2422         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2423         VMThread::execute(&op);
2424       }
2425     }
2426   } while (retry_gc);
2427 }
2428 
2429 bool G1CollectedHeap::is_in(const void* p) const {
2430   if (_hrm.reserved().contains(p)) {
2431     // Given that we know that p is in the reserved space,
2432     // heap_region_containing() should successfully
2433     // return the containing region.
2434     HeapRegion* hr = heap_region_containing(p);
2435     return hr->is_in(p);
2436   } else {
2437     return false;
2438   }
2439 }
2440 
2441 #ifdef ASSERT
2442 bool G1CollectedHeap::is_in_exact(const void* p) const {
2443   bool contains = reserved_region().contains(p);
2444   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2445   if (contains && available) {
2446     return true;
2447   } else {
2448     return false;
2449   }
2450 }
2451 #endif
2452 
2453 bool G1CollectedHeap::obj_in_cs(oop obj) {
2454   HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2455   return r != NULL && r->in_collection_set();
2456 }
2457 
2458 // Iteration functions.
2459 
2460 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2461 
2462 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2463   ExtendedOopClosure* _cl;
2464 public:
2465   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2466   bool doHeapRegion(HeapRegion* r) {
2467     if (!r->is_continues_humongous()) {
2468       r->oop_iterate(_cl);
2469     }
2470     return false;
2471   }
2472 };
2473 
2474 // Iterates an ObjectClosure over all objects within a HeapRegion.
2475 
2476 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2477   ObjectClosure* _cl;
2478 public:
2479   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2480   bool doHeapRegion(HeapRegion* r) {
2481     if (!r->is_continues_humongous()) {
2482       r->object_iterate(_cl);
2483     }
2484     return false;
2485   }
2486 };
2487 
2488 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2489   IterateObjectClosureRegionClosure blk(cl);
2490   heap_region_iterate(&blk);
2491 }
2492 
2493 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2494   _hrm.iterate(cl);
2495 }
2496 
2497 void
2498 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2499                                          uint worker_id,
2500                                          HeapRegionClaimer *hrclaimer,
2501                                          bool concurrent) const {
2502   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2503 }
2504 
2505 // Clear the cached CSet starting regions and (more importantly)
2506 // the time stamps. Called when we reset the GC time stamp.
2507 void G1CollectedHeap::clear_cset_start_regions() {
2508   assert(_worker_cset_start_region != NULL, "sanity");
2509   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2510 
2511   for (uint i = 0; i < ParallelGCThreads; i++) {
2512     _worker_cset_start_region[i] = NULL;
2513     _worker_cset_start_region_time_stamp[i] = 0;
2514   }
2515 }
2516 
2517 // Given the id of a worker, obtain or calculate a suitable
2518 // starting region for iterating over the current collection set.
2519 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2520   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2521 
2522   HeapRegion* result = NULL;
2523   unsigned gc_time_stamp = get_gc_time_stamp();
2524 
2525   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2526     // Cached starting region for current worker was set
2527     // during the current pause - so it's valid.
2528     // Note: the cached starting heap region may be NULL
2529     // (when the collection set is empty).
2530     result = _worker_cset_start_region[worker_i];
2531     assert(result == NULL || result->in_collection_set(), "sanity");
2532     return result;
2533   }
2534 
2535   // The cached entry was not valid so let's calculate
2536   // a suitable starting heap region for this worker.
2537 
2538   // We want the parallel threads to start their collection
2539   // set iteration at different collection set regions to
2540   // avoid contention.
2541   // If we have:
2542   //          n collection set regions
2543   //          p threads
2544   // Then thread t will start at region floor ((t * n) / p)
2545 
2546   result = collection_set()->head();
2547   uint cs_size = collection_set()->region_length();
2548   uint active_workers = workers()->active_workers();
2549 
2550   uint end_ind   = (cs_size * worker_i) / active_workers;
2551   uint start_ind = 0;
2552 
2553   if (worker_i > 0 &&
2554       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2555     // Previous workers starting region is valid
2556     // so let's iterate from there
2557     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2558     OrderAccess::loadload();
2559     result = _worker_cset_start_region[worker_i - 1];
2560   }
2561 
2562   for (uint i = start_ind; i < end_ind; i++) {
2563     result = result->next_in_collection_set();
2564   }
2565 
2566   // Note: the calculated starting heap region may be NULL
2567   // (when the collection set is empty).
2568   assert(result == NULL || result->in_collection_set(), "sanity");
2569   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2570          "should be updated only once per pause");
2571   _worker_cset_start_region[worker_i] = result;
2572   OrderAccess::storestore();
2573   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2574   return result;
2575 }
2576 
2577 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2578   HeapRegion* r = collection_set()->head();
2579   while (r != NULL) {
2580     HeapRegion* next = r->next_in_collection_set();
2581     if (cl->doHeapRegion(r)) {
2582       cl->incomplete();
2583       return;
2584     }
2585     r = next;
2586   }
2587 }
2588 
2589 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2590                                                   HeapRegionClosure *cl) {
2591   if (r == NULL) {
2592     // The CSet is empty so there's nothing to do.
2593     return;
2594   }
2595 
2596   assert(r->in_collection_set(),
2597          "Start region must be a member of the collection set.");
2598   HeapRegion* cur = r;
2599   while (cur != NULL) {
2600     HeapRegion* next = cur->next_in_collection_set();
2601     if (cl->doHeapRegion(cur) && false) {
2602       cl->incomplete();
2603       return;
2604     }
2605     cur = next;
2606   }
2607   cur = collection_set()->head();
2608   while (cur != r) {
2609     HeapRegion* next = cur->next_in_collection_set();
2610     if (cl->doHeapRegion(cur) && false) {
2611       cl->incomplete();
2612       return;
2613     }
2614     cur = next;
2615   }
2616 }
2617 
2618 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2619   HeapRegion* result = _hrm.next_region_in_heap(from);
2620   while (result != NULL && result->is_pinned()) {
2621     result = _hrm.next_region_in_heap(result);
2622   }
2623   return result;
2624 }
2625 
2626 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2627   HeapRegion* hr = heap_region_containing(addr);
2628   return hr->block_start(addr);
2629 }
2630 
2631 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2632   HeapRegion* hr = heap_region_containing(addr);
2633   return hr->block_size(addr);
2634 }
2635 
2636 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2637   HeapRegion* hr = heap_region_containing(addr);
2638   return hr->block_is_obj(addr);
2639 }
2640 
2641 bool G1CollectedHeap::supports_tlab_allocation() const {
2642   return true;
2643 }
2644 
2645 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2646   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2647 }
2648 
2649 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2650   return young_list()->eden_used_bytes();
2651 }
2652 
2653 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2654 // must be equal to the humongous object limit.
2655 size_t G1CollectedHeap::max_tlab_size() const {
2656   return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2657 }
2658 
2659 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2660   AllocationContext_t context = AllocationContext::current();
2661   return _allocator->unsafe_max_tlab_alloc(context);
2662 }
2663 
2664 size_t G1CollectedHeap::max_capacity() const {
2665   return _hrm.reserved().byte_size();
2666 }
2667 
2668 jlong G1CollectedHeap::millis_since_last_gc() {
2669   // assert(false, "NYI");
2670   return 0;
2671 }
2672 
2673 void G1CollectedHeap::prepare_for_verify() {
2674   _verifier->prepare_for_verify();
2675 }
2676 
2677 void G1CollectedHeap::verify(VerifyOption vo) {
2678   _verifier->verify(vo);
2679 }
2680 
2681 class PrintRegionClosure: public HeapRegionClosure {
2682   outputStream* _st;
2683 public:
2684   PrintRegionClosure(outputStream* st) : _st(st) {}
2685   bool doHeapRegion(HeapRegion* r) {
2686     r->print_on(_st);
2687     return false;
2688   }
2689 };
2690 
2691 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2692                                        const HeapRegion* hr,
2693                                        const VerifyOption vo) const {
2694   switch (vo) {
2695   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2696   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2697   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
2698   default:                            ShouldNotReachHere();
2699   }
2700   return false; // keep some compilers happy
2701 }
2702 
2703 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2704                                        const VerifyOption vo) const {
2705   switch (vo) {
2706   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2707   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2708   case VerifyOption_G1UseMarkWord: {
2709     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2710     return !obj->is_gc_marked() && !hr->is_archive();
2711   }
2712   default:                            ShouldNotReachHere();
2713   }
2714   return false; // keep some compilers happy
2715 }
2716 
2717 void G1CollectedHeap::print_on(outputStream* st) const {
2718   st->print(" %-20s", "garbage-first heap");
2719   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2720             capacity()/K, used_unlocked()/K);
2721   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2722             p2i(_hrm.reserved().start()),
2723             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2724             p2i(_hrm.reserved().end()));
2725   st->cr();
2726   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2727   uint young_regions = _young_list->length();
2728   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2729             (size_t) young_regions * HeapRegion::GrainBytes / K);
2730   uint survivor_regions = g1_policy()->recorded_survivor_regions();
2731   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2732             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2733   st->cr();
2734   MetaspaceAux::print_on(st);
2735 }
2736 
2737 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2738   print_on(st);
2739 
2740   // Print the per-region information.
2741   st->cr();
2742   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2743                "HS=humongous(starts), HC=humongous(continues), "
2744                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2745                "AC=allocation context, "
2746                "TAMS=top-at-mark-start (previous, next)");
2747   PrintRegionClosure blk(st);
2748   heap_region_iterate(&blk);
2749 }
2750 
2751 void G1CollectedHeap::print_on_error(outputStream* st) const {
2752   this->CollectedHeap::print_on_error(st);
2753 
2754   if (_cm != NULL) {
2755     st->cr();
2756     _cm->print_on_error(st);
2757   }
2758 }
2759 
2760 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2761   workers()->print_worker_threads_on(st);
2762   _cmThread->print_on(st);
2763   st->cr();
2764   _cm->print_worker_threads_on(st);
2765   _cg1r->print_worker_threads_on(st);
2766   if (G1StringDedup::is_enabled()) {
2767     G1StringDedup::print_worker_threads_on(st);
2768   }
2769 }
2770 
2771 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2772   workers()->threads_do(tc);
2773   tc->do_thread(_cmThread);
2774   _cg1r->threads_do(tc);
2775   if (G1StringDedup::is_enabled()) {
2776     G1StringDedup::threads_do(tc);
2777   }
2778 }
2779 
2780 void G1CollectedHeap::print_tracing_info() const {
2781   g1_rem_set()->print_summary_info();
2782   concurrent_mark()->print_summary_info();
2783   g1_policy()->print_yg_surv_rate_info();
2784 }
2785 
2786 #ifndef PRODUCT
2787 // Helpful for debugging RSet issues.
2788 
2789 class PrintRSetsClosure : public HeapRegionClosure {
2790 private:
2791   const char* _msg;
2792   size_t _occupied_sum;
2793 
2794 public:
2795   bool doHeapRegion(HeapRegion* r) {
2796     HeapRegionRemSet* hrrs = r->rem_set();
2797     size_t occupied = hrrs->occupied();
2798     _occupied_sum += occupied;
2799 
2800     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2801     if (occupied == 0) {
2802       tty->print_cr("  RSet is empty");
2803     } else {
2804       hrrs->print();
2805     }
2806     tty->print_cr("----------");
2807     return false;
2808   }
2809 
2810   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2811     tty->cr();
2812     tty->print_cr("========================================");
2813     tty->print_cr("%s", msg);
2814     tty->cr();
2815   }
2816 
2817   ~PrintRSetsClosure() {
2818     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2819     tty->print_cr("========================================");
2820     tty->cr();
2821   }
2822 };
2823 
2824 void G1CollectedHeap::print_cset_rsets() {
2825   PrintRSetsClosure cl("Printing CSet RSets");
2826   collection_set_iterate(&cl);
2827 }
2828 
2829 void G1CollectedHeap::print_all_rsets() {
2830   PrintRSetsClosure cl("Printing All RSets");;
2831   heap_region_iterate(&cl);
2832 }
2833 #endif // PRODUCT
2834 
2835 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2836   YoungList* young_list = heap()->young_list();
2837 
2838   size_t eden_used_bytes = young_list->eden_used_bytes();
2839   size_t survivor_used_bytes = young_list->survivor_used_bytes();
2840 
2841   size_t eden_capacity_bytes =
2842     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2843 
2844   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2845   return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes, num_regions());
2846 }
2847 
2848 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2849   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2850                        stats->unused(), stats->used(), stats->region_end_waste(),
2851                        stats->regions_filled(), stats->direct_allocated(),
2852                        stats->failure_used(), stats->failure_waste());
2853 }
2854 
2855 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2856   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2857   gc_tracer->report_gc_heap_summary(when, heap_summary);
2858 
2859   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2860   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2861 }
2862 
2863 
2864 G1CollectedHeap* G1CollectedHeap::heap() {
2865   CollectedHeap* heap = Universe::heap();
2866   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2867   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2868   return (G1CollectedHeap*)heap;
2869 }
2870 
2871 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2872   // always_do_update_barrier = false;
2873   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2874   // Fill TLAB's and such
2875   accumulate_statistics_all_tlabs();
2876   ensure_parsability(true);
2877 
2878   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2879 }
2880 
2881 void G1CollectedHeap::gc_epilogue(bool full) {
2882   // we are at the end of the GC. Total collections has already been increased.
2883   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2884 
2885   // FIXME: what is this about?
2886   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2887   // is set.
2888 #if defined(COMPILER2) || INCLUDE_JVMCI
2889   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2890 #endif
2891   // always_do_update_barrier = true;
2892 
2893   resize_all_tlabs();
2894   allocation_context_stats().update(full);
2895 
2896   // We have just completed a GC. Update the soft reference
2897   // policy with the new heap occupancy
2898   Universe::update_heap_info_at_gc();
2899 }
2900 
2901 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2902                                                uint gc_count_before,
2903                                                bool* succeeded,
2904                                                GCCause::Cause gc_cause) {
2905   assert_heap_not_locked_and_not_at_safepoint();
2906   VM_G1IncCollectionPause op(gc_count_before,
2907                              word_size,
2908                              false, /* should_initiate_conc_mark */
2909                              g1_policy()->max_pause_time_ms(),
2910                              gc_cause);
2911 
2912   op.set_allocation_context(AllocationContext::current());
2913   VMThread::execute(&op);
2914 
2915   HeapWord* result = op.result();
2916   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2917   assert(result == NULL || ret_succeeded,
2918          "the result should be NULL if the VM did not succeed");
2919   *succeeded = ret_succeeded;
2920 
2921   assert_heap_not_locked();
2922   return result;
2923 }
2924 
2925 void
2926 G1CollectedHeap::doConcurrentMark() {
2927   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2928   if (!_cmThread->in_progress()) {
2929     _cmThread->set_started();
2930     CGC_lock->notify();
2931   }
2932 }
2933 
2934 size_t G1CollectedHeap::pending_card_num() {
2935   size_t extra_cards = 0;
2936   JavaThread *curr = Threads::first();
2937   while (curr != NULL) {
2938     DirtyCardQueue& dcq = curr->dirty_card_queue();
2939     extra_cards += dcq.size();
2940     curr = curr->next();
2941   }
2942   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2943   size_t buffer_size = dcqs.buffer_size();
2944   size_t buffer_num = dcqs.completed_buffers_num();
2945 
2946   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2947   // in bytes - not the number of 'entries'. We need to convert
2948   // into a number of cards.
2949   return (buffer_size * buffer_num + extra_cards) / oopSize;
2950 }
2951 
2952 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2953  private:
2954   size_t _total_humongous;
2955   size_t _candidate_humongous;
2956 
2957   DirtyCardQueue _dcq;
2958 
2959   // We don't nominate objects with many remembered set entries, on
2960   // the assumption that such objects are likely still live.
2961   bool is_remset_small(HeapRegion* region) const {
2962     HeapRegionRemSet* const rset = region->rem_set();
2963     return G1EagerReclaimHumongousObjectsWithStaleRefs
2964       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2965       : rset->is_empty();
2966   }
2967 
2968   bool is_typeArray_region(HeapRegion* region) const {
2969     return oop(region->bottom())->is_typeArray();
2970   }
2971 
2972   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2973     assert(region->is_starts_humongous(), "Must start a humongous object");
2974 
2975     // Candidate selection must satisfy the following constraints
2976     // while concurrent marking is in progress:
2977     //
2978     // * In order to maintain SATB invariants, an object must not be
2979     // reclaimed if it was allocated before the start of marking and
2980     // has not had its references scanned.  Such an object must have
2981     // its references (including type metadata) scanned to ensure no
2982     // live objects are missed by the marking process.  Objects
2983     // allocated after the start of concurrent marking don't need to
2984     // be scanned.
2985     //
2986     // * An object must not be reclaimed if it is on the concurrent
2987     // mark stack.  Objects allocated after the start of concurrent
2988     // marking are never pushed on the mark stack.
2989     //
2990     // Nominating only objects allocated after the start of concurrent
2991     // marking is sufficient to meet both constraints.  This may miss
2992     // some objects that satisfy the constraints, but the marking data
2993     // structures don't support efficiently performing the needed
2994     // additional tests or scrubbing of the mark stack.
2995     //
2996     // However, we presently only nominate is_typeArray() objects.
2997     // A humongous object containing references induces remembered
2998     // set entries on other regions.  In order to reclaim such an
2999     // object, those remembered sets would need to be cleaned up.
3000     //
3001     // We also treat is_typeArray() objects specially, allowing them
3002     // to be reclaimed even if allocated before the start of
3003     // concurrent mark.  For this we rely on mark stack insertion to
3004     // exclude is_typeArray() objects, preventing reclaiming an object
3005     // that is in the mark stack.  We also rely on the metadata for
3006     // such objects to be built-in and so ensured to be kept live.
3007     // Frequent allocation and drop of large binary blobs is an
3008     // important use case for eager reclaim, and this special handling
3009     // may reduce needed headroom.
3010 
3011     return is_typeArray_region(region) && is_remset_small(region);
3012   }
3013 
3014  public:
3015   RegisterHumongousWithInCSetFastTestClosure()
3016   : _total_humongous(0),
3017     _candidate_humongous(0),
3018     _dcq(&JavaThread::dirty_card_queue_set()) {
3019   }
3020 
3021   virtual bool doHeapRegion(HeapRegion* r) {
3022     if (!r->is_starts_humongous()) {
3023       return false;
3024     }
3025     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3026 
3027     bool is_candidate = humongous_region_is_candidate(g1h, r);
3028     uint rindex = r->hrm_index();
3029     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3030     if (is_candidate) {
3031       _candidate_humongous++;
3032       g1h->register_humongous_region_with_cset(rindex);
3033       // Is_candidate already filters out humongous object with large remembered sets.
3034       // If we have a humongous object with a few remembered sets, we simply flush these
3035       // remembered set entries into the DCQS. That will result in automatic
3036       // re-evaluation of their remembered set entries during the following evacuation
3037       // phase.
3038       if (!r->rem_set()->is_empty()) {
3039         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3040                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3041         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3042         HeapRegionRemSetIterator hrrs(r->rem_set());
3043         size_t card_index;
3044         while (hrrs.has_next(card_index)) {
3045           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3046           // The remembered set might contain references to already freed
3047           // regions. Filter out such entries to avoid failing card table
3048           // verification.
3049           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3050             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3051               *card_ptr = CardTableModRefBS::dirty_card_val();
3052               _dcq.enqueue(card_ptr);
3053             }
3054           }
3055         }
3056         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3057                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3058                hrrs.n_yielded(), r->rem_set()->occupied());
3059         r->rem_set()->clear_locked();
3060       }
3061       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3062     }
3063     _total_humongous++;
3064 
3065     return false;
3066   }
3067 
3068   size_t total_humongous() const { return _total_humongous; }
3069   size_t candidate_humongous() const { return _candidate_humongous; }
3070 
3071   void flush_rem_set_entries() { _dcq.flush(); }
3072 };
3073 
3074 void G1CollectedHeap::register_humongous_regions_with_cset() {
3075   if (!G1EagerReclaimHumongousObjects) {
3076     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3077     return;
3078   }
3079   double time = os::elapsed_counter();
3080 
3081   // Collect reclaim candidate information and register candidates with cset.
3082   RegisterHumongousWithInCSetFastTestClosure cl;
3083   heap_region_iterate(&cl);
3084 
3085   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3086   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3087                                                                   cl.total_humongous(),
3088                                                                   cl.candidate_humongous());
3089   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3090 
3091   // Finally flush all remembered set entries to re-check into the global DCQS.
3092   cl.flush_rem_set_entries();
3093 }
3094 
3095 class VerifyRegionRemSetClosure : public HeapRegionClosure {
3096   public:
3097     bool doHeapRegion(HeapRegion* hr) {
3098       if (!hr->is_archive() && !hr->is_continues_humongous()) {
3099         hr->verify_rem_set();
3100       }
3101       return false;
3102     }
3103 };
3104 
3105 #ifdef ASSERT
3106 class VerifyCSetClosure: public HeapRegionClosure {
3107 public:
3108   bool doHeapRegion(HeapRegion* hr) {
3109     // Here we check that the CSet region's RSet is ready for parallel
3110     // iteration. The fields that we'll verify are only manipulated
3111     // when the region is part of a CSet and is collected. Afterwards,
3112     // we reset these fields when we clear the region's RSet (when the
3113     // region is freed) so they are ready when the region is
3114     // re-allocated. The only exception to this is if there's an
3115     // evacuation failure and instead of freeing the region we leave
3116     // it in the heap. In that case, we reset these fields during
3117     // evacuation failure handling.
3118     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3119 
3120     // Here's a good place to add any other checks we'd like to
3121     // perform on CSet regions.
3122     return false;
3123   }
3124 };
3125 #endif // ASSERT
3126 
3127 uint G1CollectedHeap::num_task_queues() const {
3128   return _task_queues->size();
3129 }
3130 
3131 #if TASKQUEUE_STATS
3132 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3133   st->print_raw_cr("GC Task Stats");
3134   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3135   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3136 }
3137 
3138 void G1CollectedHeap::print_taskqueue_stats() const {
3139   if (!log_develop_is_enabled(Trace, gc, task, stats)) {
3140     return;
3141   }
3142   LogHandle(gc, task, stats) log;
3143   ResourceMark rm;
3144   outputStream* st = log.trace_stream();
3145 
3146   print_taskqueue_stats_hdr(st);
3147 
3148   TaskQueueStats totals;
3149   const uint n = num_task_queues();
3150   for (uint i = 0; i < n; ++i) {
3151     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3152     totals += task_queue(i)->stats;
3153   }
3154   st->print_raw("tot "); totals.print(st); st->cr();
3155 
3156   DEBUG_ONLY(totals.verify());
3157 }
3158 
3159 void G1CollectedHeap::reset_taskqueue_stats() {
3160   const uint n = num_task_queues();
3161   for (uint i = 0; i < n; ++i) {
3162     task_queue(i)->stats.reset();
3163   }
3164 }
3165 #endif // TASKQUEUE_STATS
3166 
3167 void G1CollectedHeap::wait_for_root_region_scanning() {
3168   double scan_wait_start = os::elapsedTime();
3169   // We have to wait until the CM threads finish scanning the
3170   // root regions as it's the only way to ensure that all the
3171   // objects on them have been correctly scanned before we start
3172   // moving them during the GC.
3173   bool waited = _cm->root_regions()->wait_until_scan_finished();
3174   double wait_time_ms = 0.0;
3175   if (waited) {
3176     double scan_wait_end = os::elapsedTime();
3177     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3178   }
3179   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3180 }
3181 
3182 bool
3183 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3184   assert_at_safepoint(true /* should_be_vm_thread */);
3185   guarantee(!is_gc_active(), "collection is not reentrant");
3186 
3187   if (GCLocker::check_active_before_gc()) {
3188     return false;
3189   }
3190 
3191   _gc_timer_stw->register_gc_start();
3192 
3193   GCIdMark gc_id_mark;
3194   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3195 
3196   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3197   ResourceMark rm;
3198 
3199   wait_for_root_region_scanning();
3200 
3201   print_heap_before_gc();
3202   trace_heap_before_gc(_gc_tracer_stw);
3203 
3204   _verifier->verify_region_sets_optional();
3205   _verifier->verify_dirty_young_regions();
3206 
3207   // This call will decide whether this pause is an initial-mark
3208   // pause. If it is, during_initial_mark_pause() will return true
3209   // for the duration of this pause.
3210   g1_policy()->decide_on_conc_mark_initiation();
3211 
3212   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3213   assert(!collector_state()->during_initial_mark_pause() ||
3214           collector_state()->gcs_are_young(), "sanity");
3215 
3216   // We also do not allow mixed GCs during marking.
3217   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3218 
3219   // Record whether this pause is an initial mark. When the current
3220   // thread has completed its logging output and it's safe to signal
3221   // the CM thread, the flag's value in the policy has been reset.
3222   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3223 
3224   // Inner scope for scope based logging, timers, and stats collection
3225   {
3226     EvacuationInfo evacuation_info;
3227 
3228     if (collector_state()->during_initial_mark_pause()) {
3229       // We are about to start a marking cycle, so we increment the
3230       // full collection counter.
3231       increment_old_marking_cycles_started();
3232       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3233     }
3234 
3235     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3236 
3237     GCTraceCPUTime tcpu;
3238 
3239     FormatBuffer<> gc_string("Pause ");
3240     if (collector_state()->during_initial_mark_pause()) {
3241       gc_string.append("Initial Mark");
3242     } else if (collector_state()->gcs_are_young()) {
3243       gc_string.append("Young");
3244     } else {
3245       gc_string.append("Mixed");
3246     }
3247     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3248 
3249     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3250                                                                   workers()->active_workers(),
3251                                                                   Threads::number_of_non_daemon_threads());
3252     workers()->set_active_workers(active_workers);
3253 
3254     g1_policy()->note_gc_start(active_workers);
3255 
3256     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3257     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3258 
3259     // If the secondary_free_list is not empty, append it to the
3260     // free_list. No need to wait for the cleanup operation to finish;
3261     // the region allocation code will check the secondary_free_list
3262     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3263     // set, skip this step so that the region allocation code has to
3264     // get entries from the secondary_free_list.
3265     if (!G1StressConcRegionFreeing) {
3266       append_secondary_free_list_if_not_empty_with_lock();
3267     }
3268 
3269     G1HeapTransition heap_transition(this);
3270     size_t heap_used_bytes_before_gc = used();
3271 
3272     assert(check_young_list_well_formed(), "young list should be well formed");
3273 
3274     // Don't dynamically change the number of GC threads this early.  A value of
3275     // 0 is used to indicate serial work.  When parallel work is done,
3276     // it will be set.
3277 
3278     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3279       IsGCActiveMark x;
3280 
3281       gc_prologue(false);
3282       increment_total_collections(false /* full gc */);
3283       increment_gc_time_stamp();
3284 
3285       if (VerifyRememberedSets) {
3286         log_info(gc, verify)("[Verifying RemSets before GC]");
3287         VerifyRegionRemSetClosure v_cl;
3288         heap_region_iterate(&v_cl);
3289       }
3290 
3291       _verifier->verify_before_gc();
3292 
3293       _verifier->check_bitmaps("GC Start");
3294 
3295 #if defined(COMPILER2) || INCLUDE_JVMCI
3296       DerivedPointerTable::clear();
3297 #endif
3298 
3299       // Please see comment in g1CollectedHeap.hpp and
3300       // G1CollectedHeap::ref_processing_init() to see how
3301       // reference processing currently works in G1.
3302 
3303       // Enable discovery in the STW reference processor
3304       if (g1_policy()->should_process_references()) {
3305         ref_processor_stw()->enable_discovery();
3306       } else {
3307         ref_processor_stw()->disable_discovery();
3308       }
3309 
3310       {
3311         // We want to temporarily turn off discovery by the
3312         // CM ref processor, if necessary, and turn it back on
3313         // on again later if we do. Using a scoped
3314         // NoRefDiscovery object will do this.
3315         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3316 
3317         // Forget the current alloc region (we might even choose it to be part
3318         // of the collection set!).
3319         _allocator->release_mutator_alloc_region();
3320 
3321         // This timing is only used by the ergonomics to handle our pause target.
3322         // It is unclear why this should not include the full pause. We will
3323         // investigate this in CR 7178365.
3324         //
3325         // Preserving the old comment here if that helps the investigation:
3326         //
3327         // The elapsed time induced by the start time below deliberately elides
3328         // the possible verification above.
3329         double sample_start_time_sec = os::elapsedTime();
3330 
3331         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3332 
3333         if (collector_state()->during_initial_mark_pause()) {
3334           concurrent_mark()->checkpointRootsInitialPre();
3335         }
3336 
3337         g1_policy()->finalize_collection_set(target_pause_time_ms);
3338 
3339         evacuation_info.set_collectionset_regions(collection_set()->region_length());
3340 
3341         // Make sure the remembered sets are up to date. This needs to be
3342         // done before register_humongous_regions_with_cset(), because the
3343         // remembered sets are used there to choose eager reclaim candidates.
3344         // If the remembered sets are not up to date we might miss some
3345         // entries that need to be handled.
3346         g1_rem_set()->cleanupHRRS();
3347 
3348         register_humongous_regions_with_cset();
3349 
3350         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3351 
3352         _cm->note_start_of_gc();
3353         // We call this after finalize_cset() to
3354         // ensure that the CSet has been finalized.
3355         _cm->verify_no_cset_oops();
3356 
3357         if (_hr_printer.is_active()) {
3358           HeapRegion* hr = collection_set()->head();
3359           while (hr != NULL) {
3360             _hr_printer.cset(hr);
3361             hr = hr->next_in_collection_set();
3362           }
3363         }
3364 
3365 #ifdef ASSERT
3366         VerifyCSetClosure cl;
3367         collection_set_iterate(&cl);
3368 #endif // ASSERT
3369 
3370         // Initialize the GC alloc regions.
3371         _allocator->init_gc_alloc_regions(evacuation_info);
3372 
3373         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3374         pre_evacuate_collection_set();
3375 
3376         // Actually do the work...
3377         evacuate_collection_set(evacuation_info, &per_thread_states);
3378 
3379         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3380 
3381         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3382         free_collection_set(collection_set()->head(), evacuation_info, surviving_young_words);
3383 
3384         eagerly_reclaim_humongous_regions();
3385 
3386         collection_set()->clear_head();
3387 
3388         // Start a new incremental collection set for the next pause.
3389         collection_set()->start_incremental_building();
3390 
3391         clear_cset_fast_test();
3392 
3393         // Don't check the whole heap at this point as the
3394         // GC alloc regions from this pause have been tagged
3395         // as survivors and moved on to the survivor list.
3396         // Survivor regions will fail the !is_young() check.
3397         assert(check_young_list_empty(false /* check_heap */),
3398           "young list should be empty");
3399 
3400         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3401                                              _young_list->first_survivor_region(),
3402                                              _young_list->last_survivor_region());
3403 
3404         _young_list->reset_auxilary_lists();
3405 
3406         if (evacuation_failed()) {
3407           set_used(recalculate_used());
3408           if (_archive_allocator != NULL) {
3409             _archive_allocator->clear_used();
3410           }
3411           for (uint i = 0; i < ParallelGCThreads; i++) {
3412             if (_evacuation_failed_info_array[i].has_failed()) {
3413               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3414             }
3415           }
3416         } else {
3417           // The "used" of the the collection set have already been subtracted
3418           // when they were freed.  Add in the bytes evacuated.
3419           increase_used(g1_policy()->bytes_copied_during_gc());
3420         }
3421 
3422         if (collector_state()->during_initial_mark_pause()) {
3423           // We have to do this before we notify the CM threads that
3424           // they can start working to make sure that all the
3425           // appropriate initialization is done on the CM object.
3426           concurrent_mark()->checkpointRootsInitialPost();
3427           collector_state()->set_mark_in_progress(true);
3428           // Note that we don't actually trigger the CM thread at
3429           // this point. We do that later when we're sure that
3430           // the current thread has completed its logging output.
3431         }
3432 
3433         allocate_dummy_regions();
3434 
3435         _allocator->init_mutator_alloc_region();
3436 
3437         {
3438           size_t expand_bytes = g1_policy()->expansion_amount();
3439           if (expand_bytes > 0) {
3440             size_t bytes_before = capacity();
3441             // No need for an ergo logging here,
3442             // expansion_amount() does this when it returns a value > 0.
3443             double expand_ms;
3444             if (!expand(expand_bytes, &expand_ms)) {
3445               // We failed to expand the heap. Cannot do anything about it.
3446             }
3447             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3448           }
3449         }
3450 
3451         // We redo the verification but now wrt to the new CSet which
3452         // has just got initialized after the previous CSet was freed.
3453         _cm->verify_no_cset_oops();
3454         _cm->note_end_of_gc();
3455 
3456         // This timing is only used by the ergonomics to handle our pause target.
3457         // It is unclear why this should not include the full pause. We will
3458         // investigate this in CR 7178365.
3459         double sample_end_time_sec = os::elapsedTime();
3460         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3461         size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3462         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3463 
3464         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3465         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3466 
3467         MemoryService::track_memory_usage();
3468 
3469         // In prepare_for_verify() below we'll need to scan the deferred
3470         // update buffers to bring the RSets up-to-date if
3471         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3472         // the update buffers we'll probably need to scan cards on the
3473         // regions we just allocated to (i.e., the GC alloc
3474         // regions). However, during the last GC we called
3475         // set_saved_mark() on all the GC alloc regions, so card
3476         // scanning might skip the [saved_mark_word()...top()] area of
3477         // those regions (i.e., the area we allocated objects into
3478         // during the last GC). But it shouldn't. Given that
3479         // saved_mark_word() is conditional on whether the GC time stamp
3480         // on the region is current or not, by incrementing the GC time
3481         // stamp here we invalidate all the GC time stamps on all the
3482         // regions and saved_mark_word() will simply return top() for
3483         // all the regions. This is a nicer way of ensuring this rather
3484         // than iterating over the regions and fixing them. In fact, the
3485         // GC time stamp increment here also ensures that
3486         // saved_mark_word() will return top() between pauses, i.e.,
3487         // during concurrent refinement. So we don't need the
3488         // is_gc_active() check to decided which top to use when
3489         // scanning cards (see CR 7039627).
3490         increment_gc_time_stamp();
3491 
3492         if (VerifyRememberedSets) {
3493           log_info(gc, verify)("[Verifying RemSets after GC]");
3494           VerifyRegionRemSetClosure v_cl;
3495           heap_region_iterate(&v_cl);
3496         }
3497 
3498         _verifier->verify_after_gc();
3499         _verifier->check_bitmaps("GC End");
3500 
3501         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3502         ref_processor_stw()->verify_no_references_recorded();
3503 
3504         // CM reference discovery will be re-enabled if necessary.
3505       }
3506 
3507 #ifdef TRACESPINNING
3508       ParallelTaskTerminator::print_termination_counts();
3509 #endif
3510 
3511       gc_epilogue(false);
3512     }
3513 
3514     // Print the remainder of the GC log output.
3515     if (evacuation_failed()) {
3516       log_info(gc)("To-space exhausted");
3517     }
3518 
3519     g1_policy()->print_phases();
3520     heap_transition.print();
3521 
3522     // It is not yet to safe to tell the concurrent mark to
3523     // start as we have some optional output below. We don't want the
3524     // output from the concurrent mark thread interfering with this
3525     // logging output either.
3526 
3527     _hrm.verify_optional();
3528     _verifier->verify_region_sets_optional();
3529 
3530     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3531     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3532 
3533     print_heap_after_gc();
3534     trace_heap_after_gc(_gc_tracer_stw);
3535 
3536     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3537     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3538     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3539     // before any GC notifications are raised.
3540     g1mm()->update_sizes();
3541 
3542     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3543     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3544     _gc_timer_stw->register_gc_end();
3545     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3546   }
3547   // It should now be safe to tell the concurrent mark thread to start
3548   // without its logging output interfering with the logging output
3549   // that came from the pause.
3550 
3551   if (should_start_conc_mark) {
3552     // CAUTION: after the doConcurrentMark() call below,
3553     // the concurrent marking thread(s) could be running
3554     // concurrently with us. Make sure that anything after
3555     // this point does not assume that we are the only GC thread
3556     // running. Note: of course, the actual marking work will
3557     // not start until the safepoint itself is released in
3558     // SuspendibleThreadSet::desynchronize().
3559     doConcurrentMark();
3560   }
3561 
3562   return true;
3563 }
3564 
3565 void G1CollectedHeap::restore_preserved_marks() {
3566   G1RestorePreservedMarksTask rpm_task(_preserved_objs);
3567   workers()->run_task(&rpm_task);
3568 }
3569 
3570 void G1CollectedHeap::remove_self_forwarding_pointers() {
3571   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3572   workers()->run_task(&rsfp_task);
3573 }
3574 
3575 void G1CollectedHeap::restore_after_evac_failure() {
3576   double remove_self_forwards_start = os::elapsedTime();
3577 
3578   remove_self_forwarding_pointers();
3579   restore_preserved_marks();
3580 
3581   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3582 }
3583 
3584 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3585   if (!_evacuation_failed) {
3586     _evacuation_failed = true;
3587   }
3588 
3589   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3590 
3591   // We want to call the "for_promotion_failure" version only in the
3592   // case of a promotion failure.
3593   if (m->must_be_preserved_for_promotion_failure(obj)) {
3594     OopAndMarkOop elem(obj, m);
3595     _preserved_objs[worker_id].push(elem);
3596   }
3597 }
3598 
3599 bool G1ParEvacuateFollowersClosure::offer_termination() {
3600   G1ParScanThreadState* const pss = par_scan_state();
3601   start_term_time();
3602   const bool res = terminator()->offer_termination();
3603   end_term_time();
3604   return res;
3605 }
3606 
3607 void G1ParEvacuateFollowersClosure::do_void() {
3608   G1ParScanThreadState* const pss = par_scan_state();
3609   pss->trim_queue();
3610   do {
3611     pss->steal_and_trim_queue(queues());
3612   } while (!offer_termination());
3613 }
3614 
3615 class G1ParTask : public AbstractGangTask {
3616 protected:
3617   G1CollectedHeap*         _g1h;
3618   G1ParScanThreadStateSet* _pss;
3619   RefToScanQueueSet*       _queues;
3620   G1RootProcessor*         _root_processor;
3621   ParallelTaskTerminator   _terminator;
3622   uint                     _n_workers;
3623 
3624 public:
3625   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3626     : AbstractGangTask("G1 collection"),
3627       _g1h(g1h),
3628       _pss(per_thread_states),
3629       _queues(task_queues),
3630       _root_processor(root_processor),
3631       _terminator(n_workers, _queues),
3632       _n_workers(n_workers)
3633   {}
3634 
3635   void work(uint worker_id) {
3636     if (worker_id >= _n_workers) return;  // no work needed this round
3637 
3638     double start_sec = os::elapsedTime();
3639     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3640 
3641     {
3642       ResourceMark rm;
3643       HandleMark   hm;
3644 
3645       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3646 
3647       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3648       pss->set_ref_processor(rp);
3649 
3650       double start_strong_roots_sec = os::elapsedTime();
3651 
3652       _root_processor->evacuate_roots(pss->closures(), worker_id);
3653 
3654       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3655 
3656       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3657       // treating the nmethods visited to act as roots for concurrent marking.
3658       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3659       // objects copied by the current evacuation.
3660       size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3661                                                                              pss->closures()->weak_codeblobs(),
3662                                                                              worker_id);
3663 
3664       _pss->add_cards_scanned(worker_id, cards_scanned);
3665 
3666       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3667 
3668       double term_sec = 0.0;
3669       size_t evac_term_attempts = 0;
3670       {
3671         double start = os::elapsedTime();
3672         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3673         evac.do_void();
3674 
3675         evac_term_attempts = evac.term_attempts();
3676         term_sec = evac.term_time();
3677         double elapsed_sec = os::elapsedTime() - start;
3678         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3679         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3680         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3681       }
3682 
3683       assert(pss->queue_is_empty(), "should be empty");
3684 
3685       if (log_is_enabled(Debug, gc, task, stats)) {
3686         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3687         size_t lab_waste;
3688         size_t lab_undo_waste;
3689         pss->waste(lab_waste, lab_undo_waste);
3690         _g1h->print_termination_stats(worker_id,
3691                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3692                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3693                                       term_sec * 1000.0,                          /* evac term time */
3694                                       evac_term_attempts,                         /* evac term attempts */
3695                                       lab_waste,                                  /* alloc buffer waste */
3696                                       lab_undo_waste                              /* undo waste */
3697                                       );
3698       }
3699 
3700       // Close the inner scope so that the ResourceMark and HandleMark
3701       // destructors are executed here and are included as part of the
3702       // "GC Worker Time".
3703     }
3704     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3705   }
3706 };
3707 
3708 void G1CollectedHeap::print_termination_stats_hdr() {
3709   log_debug(gc, task, stats)("GC Termination Stats");
3710   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3711   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3712   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3713 }
3714 
3715 void G1CollectedHeap::print_termination_stats(uint worker_id,
3716                                               double elapsed_ms,
3717                                               double strong_roots_ms,
3718                                               double term_ms,
3719                                               size_t term_attempts,
3720                                               size_t alloc_buffer_waste,
3721                                               size_t undo_waste) const {
3722   log_debug(gc, task, stats)
3723               ("%3d %9.2f %9.2f %6.2f "
3724                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3725                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3726                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3727                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3728                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3729                alloc_buffer_waste * HeapWordSize / K,
3730                undo_waste * HeapWordSize / K);
3731 }
3732 
3733 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3734 private:
3735   BoolObjectClosure* _is_alive;
3736   int _initial_string_table_size;
3737   int _initial_symbol_table_size;
3738 
3739   bool  _process_strings;
3740   int _strings_processed;
3741   int _strings_removed;
3742 
3743   bool  _process_symbols;
3744   int _symbols_processed;
3745   int _symbols_removed;
3746 
3747 public:
3748   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3749     AbstractGangTask("String/Symbol Unlinking"),
3750     _is_alive(is_alive),
3751     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3752     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3753 
3754     _initial_string_table_size = StringTable::the_table()->table_size();
3755     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3756     if (process_strings) {
3757       StringTable::clear_parallel_claimed_index();
3758     }
3759     if (process_symbols) {
3760       SymbolTable::clear_parallel_claimed_index();
3761     }
3762   }
3763 
3764   ~G1StringSymbolTableUnlinkTask() {
3765     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3766               "claim value %d after unlink less than initial string table size %d",
3767               StringTable::parallel_claimed_index(), _initial_string_table_size);
3768     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3769               "claim value %d after unlink less than initial symbol table size %d",
3770               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3771 
3772     log_debug(gc, stringdedup)("Cleaned string and symbol table, "
3773                                "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3774                                "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3775                                strings_processed(), strings_removed(),
3776                                symbols_processed(), symbols_removed());
3777   }
3778 
3779   void work(uint worker_id) {
3780     int strings_processed = 0;
3781     int strings_removed = 0;
3782     int symbols_processed = 0;
3783     int symbols_removed = 0;
3784     if (_process_strings) {
3785       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3786       Atomic::add(strings_processed, &_strings_processed);
3787       Atomic::add(strings_removed, &_strings_removed);
3788     }
3789     if (_process_symbols) {
3790       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3791       Atomic::add(symbols_processed, &_symbols_processed);
3792       Atomic::add(symbols_removed, &_symbols_removed);
3793     }
3794   }
3795 
3796   size_t strings_processed() const { return (size_t)_strings_processed; }
3797   size_t strings_removed()   const { return (size_t)_strings_removed; }
3798 
3799   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3800   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3801 };
3802 
3803 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3804 private:
3805   static Monitor* _lock;
3806 
3807   BoolObjectClosure* const _is_alive;
3808   const bool               _unloading_occurred;
3809   const uint               _num_workers;
3810 
3811   // Variables used to claim nmethods.
3812   nmethod* _first_nmethod;
3813   volatile nmethod* _claimed_nmethod;
3814 
3815   // The list of nmethods that need to be processed by the second pass.
3816   volatile nmethod* _postponed_list;
3817   volatile uint     _num_entered_barrier;
3818 
3819  public:
3820   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3821       _is_alive(is_alive),
3822       _unloading_occurred(unloading_occurred),
3823       _num_workers(num_workers),
3824       _first_nmethod(NULL),
3825       _claimed_nmethod(NULL),
3826       _postponed_list(NULL),
3827       _num_entered_barrier(0)
3828   {
3829     nmethod::increase_unloading_clock();
3830     // Get first alive nmethod
3831     NMethodIterator iter = NMethodIterator();
3832     if(iter.next_alive()) {
3833       _first_nmethod = iter.method();
3834     }
3835     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
3836   }
3837 
3838   ~G1CodeCacheUnloadingTask() {
3839     CodeCache::verify_clean_inline_caches();
3840 
3841     CodeCache::set_needs_cache_clean(false);
3842     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3843 
3844     CodeCache::verify_icholder_relocations();
3845   }
3846 
3847  private:
3848   void add_to_postponed_list(nmethod* nm) {
3849       nmethod* old;
3850       do {
3851         old = (nmethod*)_postponed_list;
3852         nm->set_unloading_next(old);
3853       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3854   }
3855 
3856   void clean_nmethod(nmethod* nm) {
3857     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3858 
3859     if (postponed) {
3860       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3861       add_to_postponed_list(nm);
3862     }
3863 
3864     // Mark that this thread has been cleaned/unloaded.
3865     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3866     nm->set_unloading_clock(nmethod::global_unloading_clock());
3867   }
3868 
3869   void clean_nmethod_postponed(nmethod* nm) {
3870     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3871   }
3872 
3873   static const int MaxClaimNmethods = 16;
3874 
3875   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
3876     nmethod* first;
3877     NMethodIterator last;
3878 
3879     do {
3880       *num_claimed_nmethods = 0;
3881 
3882       first = (nmethod*)_claimed_nmethod;
3883       last = NMethodIterator(first);
3884 
3885       if (first != NULL) {
3886 
3887         for (int i = 0; i < MaxClaimNmethods; i++) {
3888           if (!last.next_alive()) {
3889             break;
3890           }
3891           claimed_nmethods[i] = last.method();
3892           (*num_claimed_nmethods)++;
3893         }
3894       }
3895 
3896     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3897   }
3898 
3899   nmethod* claim_postponed_nmethod() {
3900     nmethod* claim;
3901     nmethod* next;
3902 
3903     do {
3904       claim = (nmethod*)_postponed_list;
3905       if (claim == NULL) {
3906         return NULL;
3907       }
3908 
3909       next = claim->unloading_next();
3910 
3911     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3912 
3913     return claim;
3914   }
3915 
3916  public:
3917   // Mark that we're done with the first pass of nmethod cleaning.
3918   void barrier_mark(uint worker_id) {
3919     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3920     _num_entered_barrier++;
3921     if (_num_entered_barrier == _num_workers) {
3922       ml.notify_all();
3923     }
3924   }
3925 
3926   // See if we have to wait for the other workers to
3927   // finish their first-pass nmethod cleaning work.
3928   void barrier_wait(uint worker_id) {
3929     if (_num_entered_barrier < _num_workers) {
3930       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3931       while (_num_entered_barrier < _num_workers) {
3932           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3933       }
3934     }
3935   }
3936 
3937   // Cleaning and unloading of nmethods. Some work has to be postponed
3938   // to the second pass, when we know which nmethods survive.
3939   void work_first_pass(uint worker_id) {
3940     // The first nmethods is claimed by the first worker.
3941     if (worker_id == 0 && _first_nmethod != NULL) {
3942       clean_nmethod(_first_nmethod);
3943       _first_nmethod = NULL;
3944     }
3945 
3946     int num_claimed_nmethods;
3947     nmethod* claimed_nmethods[MaxClaimNmethods];
3948 
3949     while (true) {
3950       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3951 
3952       if (num_claimed_nmethods == 0) {
3953         break;
3954       }
3955 
3956       for (int i = 0; i < num_claimed_nmethods; i++) {
3957         clean_nmethod(claimed_nmethods[i]);
3958       }
3959     }
3960   }
3961 
3962   void work_second_pass(uint worker_id) {
3963     nmethod* nm;
3964     // Take care of postponed nmethods.
3965     while ((nm = claim_postponed_nmethod()) != NULL) {
3966       clean_nmethod_postponed(nm);
3967     }
3968   }
3969 };
3970 
3971 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3972 
3973 class G1KlassCleaningTask : public StackObj {
3974   BoolObjectClosure*                      _is_alive;
3975   volatile jint                           _clean_klass_tree_claimed;
3976   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3977 
3978  public:
3979   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3980       _is_alive(is_alive),
3981       _clean_klass_tree_claimed(0),
3982       _klass_iterator() {
3983   }
3984 
3985  private:
3986   bool claim_clean_klass_tree_task() {
3987     if (_clean_klass_tree_claimed) {
3988       return false;
3989     }
3990 
3991     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3992   }
3993 
3994   InstanceKlass* claim_next_klass() {
3995     Klass* klass;
3996     do {
3997       klass =_klass_iterator.next_klass();
3998     } while (klass != NULL && !klass->is_instance_klass());
3999 
4000     // this can be null so don't call InstanceKlass::cast
4001     return static_cast<InstanceKlass*>(klass);
4002   }
4003 
4004 public:
4005 
4006   void clean_klass(InstanceKlass* ik) {
4007     ik->clean_weak_instanceklass_links(_is_alive);
4008   }
4009 
4010   void work() {
4011     ResourceMark rm;
4012 
4013     // One worker will clean the subklass/sibling klass tree.
4014     if (claim_clean_klass_tree_task()) {
4015       Klass::clean_subklass_tree(_is_alive);
4016     }
4017 
4018     // All workers will help cleaning the classes,
4019     InstanceKlass* klass;
4020     while ((klass = claim_next_klass()) != NULL) {
4021       clean_klass(klass);
4022     }
4023   }
4024 };
4025 
4026 // To minimize the remark pause times, the tasks below are done in parallel.
4027 class G1ParallelCleaningTask : public AbstractGangTask {
4028 private:
4029   G1StringSymbolTableUnlinkTask _string_symbol_task;
4030   G1CodeCacheUnloadingTask      _code_cache_task;
4031   G1KlassCleaningTask           _klass_cleaning_task;
4032 
4033 public:
4034   // The constructor is run in the VMThread.
4035   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4036       AbstractGangTask("Parallel Cleaning"),
4037       _string_symbol_task(is_alive, process_strings, process_symbols),
4038       _code_cache_task(num_workers, is_alive, unloading_occurred),
4039       _klass_cleaning_task(is_alive) {
4040   }
4041 
4042   // The parallel work done by all worker threads.
4043   void work(uint worker_id) {
4044     // Do first pass of code cache cleaning.
4045     _code_cache_task.work_first_pass(worker_id);
4046 
4047     // Let the threads mark that the first pass is done.
4048     _code_cache_task.barrier_mark(worker_id);
4049 
4050     // Clean the Strings and Symbols.
4051     _string_symbol_task.work(worker_id);
4052 
4053     // Wait for all workers to finish the first code cache cleaning pass.
4054     _code_cache_task.barrier_wait(worker_id);
4055 
4056     // Do the second code cache cleaning work, which realize on
4057     // the liveness information gathered during the first pass.
4058     _code_cache_task.work_second_pass(worker_id);
4059 
4060     // Clean all klasses that were not unloaded.
4061     _klass_cleaning_task.work();
4062   }
4063 };
4064 
4065 
4066 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4067                                         bool process_strings,
4068                                         bool process_symbols,
4069                                         bool class_unloading_occurred) {
4070   uint n_workers = workers()->active_workers();
4071 
4072   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4073                                         n_workers, class_unloading_occurred);
4074   workers()->run_task(&g1_unlink_task);
4075 }
4076 
4077 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4078                                                      bool process_strings, bool process_symbols) {
4079   {
4080     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4081     workers()->run_task(&g1_unlink_task);
4082   }
4083 
4084   if (G1StringDedup::is_enabled()) {
4085     G1StringDedup::unlink(is_alive);
4086   }
4087 }
4088 
4089 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4090  private:
4091   DirtyCardQueueSet* _queue;
4092   G1CollectedHeap* _g1h;
4093  public:
4094   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4095     _queue(queue), _g1h(g1h) { }
4096 
4097   virtual void work(uint worker_id) {
4098     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4099     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4100 
4101     RedirtyLoggedCardTableEntryClosure cl(_g1h);
4102     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4103 
4104     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4105   }
4106 };
4107 
4108 void G1CollectedHeap::redirty_logged_cards() {
4109   double redirty_logged_cards_start = os::elapsedTime();
4110 
4111   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4112   dirty_card_queue_set().reset_for_par_iteration();
4113   workers()->run_task(&redirty_task);
4114 
4115   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4116   dcq.merge_bufferlists(&dirty_card_queue_set());
4117   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4118 
4119   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4120 }
4121 
4122 // Weak Reference Processing support
4123 
4124 // An always "is_alive" closure that is used to preserve referents.
4125 // If the object is non-null then it's alive.  Used in the preservation
4126 // of referent objects that are pointed to by reference objects
4127 // discovered by the CM ref processor.
4128 class G1AlwaysAliveClosure: public BoolObjectClosure {
4129   G1CollectedHeap* _g1;
4130 public:
4131   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4132   bool do_object_b(oop p) {
4133     if (p != NULL) {
4134       return true;
4135     }
4136     return false;
4137   }
4138 };
4139 
4140 bool G1STWIsAliveClosure::do_object_b(oop p) {
4141   // An object is reachable if it is outside the collection set,
4142   // or is inside and copied.
4143   return !_g1->is_in_cset(p) || p->is_forwarded();
4144 }
4145 
4146 // Non Copying Keep Alive closure
4147 class G1KeepAliveClosure: public OopClosure {
4148   G1CollectedHeap* _g1;
4149 public:
4150   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4151   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4152   void do_oop(oop* p) {
4153     oop obj = *p;
4154     assert(obj != NULL, "the caller should have filtered out NULL values");
4155 
4156     const InCSetState cset_state = _g1->in_cset_state(obj);
4157     if (!cset_state.is_in_cset_or_humongous()) {
4158       return;
4159     }
4160     if (cset_state.is_in_cset()) {
4161       assert( obj->is_forwarded(), "invariant" );
4162       *p = obj->forwardee();
4163     } else {
4164       assert(!obj->is_forwarded(), "invariant" );
4165       assert(cset_state.is_humongous(),
4166              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4167       _g1->set_humongous_is_live(obj);
4168     }
4169   }
4170 };
4171 
4172 // Copying Keep Alive closure - can be called from both
4173 // serial and parallel code as long as different worker
4174 // threads utilize different G1ParScanThreadState instances
4175 // and different queues.
4176 
4177 class G1CopyingKeepAliveClosure: public OopClosure {
4178   G1CollectedHeap*         _g1h;
4179   OopClosure*              _copy_non_heap_obj_cl;
4180   G1ParScanThreadState*    _par_scan_state;
4181 
4182 public:
4183   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4184                             OopClosure* non_heap_obj_cl,
4185                             G1ParScanThreadState* pss):
4186     _g1h(g1h),
4187     _copy_non_heap_obj_cl(non_heap_obj_cl),
4188     _par_scan_state(pss)
4189   {}
4190 
4191   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4192   virtual void do_oop(      oop* p) { do_oop_work(p); }
4193 
4194   template <class T> void do_oop_work(T* p) {
4195     oop obj = oopDesc::load_decode_heap_oop(p);
4196 
4197     if (_g1h->is_in_cset_or_humongous(obj)) {
4198       // If the referent object has been forwarded (either copied
4199       // to a new location or to itself in the event of an
4200       // evacuation failure) then we need to update the reference
4201       // field and, if both reference and referent are in the G1
4202       // heap, update the RSet for the referent.
4203       //
4204       // If the referent has not been forwarded then we have to keep
4205       // it alive by policy. Therefore we have copy the referent.
4206       //
4207       // If the reference field is in the G1 heap then we can push
4208       // on the PSS queue. When the queue is drained (after each
4209       // phase of reference processing) the object and it's followers
4210       // will be copied, the reference field set to point to the
4211       // new location, and the RSet updated. Otherwise we need to
4212       // use the the non-heap or metadata closures directly to copy
4213       // the referent object and update the pointer, while avoiding
4214       // updating the RSet.
4215 
4216       if (_g1h->is_in_g1_reserved(p)) {
4217         _par_scan_state->push_on_queue(p);
4218       } else {
4219         assert(!Metaspace::contains((const void*)p),
4220                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4221         _copy_non_heap_obj_cl->do_oop(p);
4222       }
4223     }
4224   }
4225 };
4226 
4227 // Serial drain queue closure. Called as the 'complete_gc'
4228 // closure for each discovered list in some of the
4229 // reference processing phases.
4230 
4231 class G1STWDrainQueueClosure: public VoidClosure {
4232 protected:
4233   G1CollectedHeap* _g1h;
4234   G1ParScanThreadState* _par_scan_state;
4235 
4236   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4237 
4238 public:
4239   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4240     _g1h(g1h),
4241     _par_scan_state(pss)
4242   { }
4243 
4244   void do_void() {
4245     G1ParScanThreadState* const pss = par_scan_state();
4246     pss->trim_queue();
4247   }
4248 };
4249 
4250 // Parallel Reference Processing closures
4251 
4252 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4253 // processing during G1 evacuation pauses.
4254 
4255 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4256 private:
4257   G1CollectedHeap*          _g1h;
4258   G1ParScanThreadStateSet*  _pss;
4259   RefToScanQueueSet*        _queues;
4260   WorkGang*                 _workers;
4261   uint                      _active_workers;
4262 
4263 public:
4264   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4265                            G1ParScanThreadStateSet* per_thread_states,
4266                            WorkGang* workers,
4267                            RefToScanQueueSet *task_queues,
4268                            uint n_workers) :
4269     _g1h(g1h),
4270     _pss(per_thread_states),
4271     _queues(task_queues),
4272     _workers(workers),
4273     _active_workers(n_workers)
4274   {
4275     assert(n_workers > 0, "shouldn't call this otherwise");
4276   }
4277 
4278   // Executes the given task using concurrent marking worker threads.
4279   virtual void execute(ProcessTask& task);
4280   virtual void execute(EnqueueTask& task);
4281 };
4282 
4283 // Gang task for possibly parallel reference processing
4284 
4285 class G1STWRefProcTaskProxy: public AbstractGangTask {
4286   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4287   ProcessTask&     _proc_task;
4288   G1CollectedHeap* _g1h;
4289   G1ParScanThreadStateSet* _pss;
4290   RefToScanQueueSet* _task_queues;
4291   ParallelTaskTerminator* _terminator;
4292 
4293 public:
4294   G1STWRefProcTaskProxy(ProcessTask& proc_task,
4295                         G1CollectedHeap* g1h,
4296                         G1ParScanThreadStateSet* per_thread_states,
4297                         RefToScanQueueSet *task_queues,
4298                         ParallelTaskTerminator* terminator) :
4299     AbstractGangTask("Process reference objects in parallel"),
4300     _proc_task(proc_task),
4301     _g1h(g1h),
4302     _pss(per_thread_states),
4303     _task_queues(task_queues),
4304     _terminator(terminator)
4305   {}
4306 
4307   virtual void work(uint worker_id) {
4308     // The reference processing task executed by a single worker.
4309     ResourceMark rm;
4310     HandleMark   hm;
4311 
4312     G1STWIsAliveClosure is_alive(_g1h);
4313 
4314     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4315     pss->set_ref_processor(NULL);
4316 
4317     // Keep alive closure.
4318     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4319 
4320     // Complete GC closure
4321     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4322 
4323     // Call the reference processing task's work routine.
4324     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4325 
4326     // Note we cannot assert that the refs array is empty here as not all
4327     // of the processing tasks (specifically phase2 - pp2_work) execute
4328     // the complete_gc closure (which ordinarily would drain the queue) so
4329     // the queue may not be empty.
4330   }
4331 };
4332 
4333 // Driver routine for parallel reference processing.
4334 // Creates an instance of the ref processing gang
4335 // task and has the worker threads execute it.
4336 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4337   assert(_workers != NULL, "Need parallel worker threads.");
4338 
4339   ParallelTaskTerminator terminator(_active_workers, _queues);
4340   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4341 
4342   _workers->run_task(&proc_task_proxy);
4343 }
4344 
4345 // Gang task for parallel reference enqueueing.
4346 
4347 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4348   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4349   EnqueueTask& _enq_task;
4350 
4351 public:
4352   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4353     AbstractGangTask("Enqueue reference objects in parallel"),
4354     _enq_task(enq_task)
4355   { }
4356 
4357   virtual void work(uint worker_id) {
4358     _enq_task.work(worker_id);
4359   }
4360 };
4361 
4362 // Driver routine for parallel reference enqueueing.
4363 // Creates an instance of the ref enqueueing gang
4364 // task and has the worker threads execute it.
4365 
4366 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4367   assert(_workers != NULL, "Need parallel worker threads.");
4368 
4369   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4370 
4371   _workers->run_task(&enq_task_proxy);
4372 }
4373 
4374 // End of weak reference support closures
4375 
4376 // Abstract task used to preserve (i.e. copy) any referent objects
4377 // that are in the collection set and are pointed to by reference
4378 // objects discovered by the CM ref processor.
4379 
4380 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4381 protected:
4382   G1CollectedHeap*         _g1h;
4383   G1ParScanThreadStateSet* _pss;
4384   RefToScanQueueSet*       _queues;
4385   ParallelTaskTerminator   _terminator;
4386   uint                     _n_workers;
4387 
4388 public:
4389   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4390     AbstractGangTask("ParPreserveCMReferents"),
4391     _g1h(g1h),
4392     _pss(per_thread_states),
4393     _queues(task_queues),
4394     _terminator(workers, _queues),
4395     _n_workers(workers)
4396   { }
4397 
4398   void work(uint worker_id) {
4399     ResourceMark rm;
4400     HandleMark   hm;
4401 
4402     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4403     pss->set_ref_processor(NULL);
4404     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4405 
4406     // Is alive closure
4407     G1AlwaysAliveClosure always_alive(_g1h);
4408 
4409     // Copying keep alive closure. Applied to referent objects that need
4410     // to be copied.
4411     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4412 
4413     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4414 
4415     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4416     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4417 
4418     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4419     // So this must be true - but assert just in case someone decides to
4420     // change the worker ids.
4421     assert(worker_id < limit, "sanity");
4422     assert(!rp->discovery_is_atomic(), "check this code");
4423 
4424     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4425     for (uint idx = worker_id; idx < limit; idx += stride) {
4426       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4427 
4428       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4429       while (iter.has_next()) {
4430         // Since discovery is not atomic for the CM ref processor, we
4431         // can see some null referent objects.
4432         iter.load_ptrs(DEBUG_ONLY(true));
4433         oop ref = iter.obj();
4434 
4435         // This will filter nulls.
4436         if (iter.is_referent_alive()) {
4437           iter.make_referent_alive();
4438         }
4439         iter.move_to_next();
4440       }
4441     }
4442 
4443     // Drain the queue - which may cause stealing
4444     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4445     drain_queue.do_void();
4446     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4447     assert(pss->queue_is_empty(), "should be");
4448   }
4449 };
4450 
4451 void G1CollectedHeap::process_weak_jni_handles() {
4452   double ref_proc_start = os::elapsedTime();
4453 
4454   G1STWIsAliveClosure is_alive(this);
4455   G1KeepAliveClosure keep_alive(this);
4456   JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4457 
4458   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4459   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4460 }
4461 
4462 // Weak Reference processing during an evacuation pause (part 1).
4463 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4464   double ref_proc_start = os::elapsedTime();
4465 
4466   ReferenceProcessor* rp = _ref_processor_stw;
4467   assert(rp->discovery_enabled(), "should have been enabled");
4468 
4469   // Any reference objects, in the collection set, that were 'discovered'
4470   // by the CM ref processor should have already been copied (either by
4471   // applying the external root copy closure to the discovered lists, or
4472   // by following an RSet entry).
4473   //
4474   // But some of the referents, that are in the collection set, that these
4475   // reference objects point to may not have been copied: the STW ref
4476   // processor would have seen that the reference object had already
4477   // been 'discovered' and would have skipped discovering the reference,
4478   // but would not have treated the reference object as a regular oop.
4479   // As a result the copy closure would not have been applied to the
4480   // referent object.
4481   //
4482   // We need to explicitly copy these referent objects - the references
4483   // will be processed at the end of remarking.
4484   //
4485   // We also need to do this copying before we process the reference
4486   // objects discovered by the STW ref processor in case one of these
4487   // referents points to another object which is also referenced by an
4488   // object discovered by the STW ref processor.
4489 
4490   uint no_of_gc_workers = workers()->active_workers();
4491 
4492   G1ParPreserveCMReferentsTask keep_cm_referents(this,
4493                                                  per_thread_states,
4494                                                  no_of_gc_workers,
4495                                                  _task_queues);
4496 
4497   workers()->run_task(&keep_cm_referents);
4498 
4499   // Closure to test whether a referent is alive.
4500   G1STWIsAliveClosure is_alive(this);
4501 
4502   // Even when parallel reference processing is enabled, the processing
4503   // of JNI refs is serial and performed serially by the current thread
4504   // rather than by a worker. The following PSS will be used for processing
4505   // JNI refs.
4506 
4507   // Use only a single queue for this PSS.
4508   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4509   pss->set_ref_processor(NULL);
4510   assert(pss->queue_is_empty(), "pre-condition");
4511 
4512   // Keep alive closure.
4513   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4514 
4515   // Serial Complete GC closure
4516   G1STWDrainQueueClosure drain_queue(this, pss);
4517 
4518   // Setup the soft refs policy...
4519   rp->setup_policy(false);
4520 
4521   ReferenceProcessorStats stats;
4522   if (!rp->processing_is_mt()) {
4523     // Serial reference processing...
4524     stats = rp->process_discovered_references(&is_alive,
4525                                               &keep_alive,
4526                                               &drain_queue,
4527                                               NULL,
4528                                               _gc_timer_stw);
4529   } else {
4530     // Parallel reference processing
4531     assert(rp->num_q() == no_of_gc_workers, "sanity");
4532     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
4533 
4534     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4535     stats = rp->process_discovered_references(&is_alive,
4536                                               &keep_alive,
4537                                               &drain_queue,
4538                                               &par_task_executor,
4539                                               _gc_timer_stw);
4540   }
4541 
4542   _gc_tracer_stw->report_gc_reference_stats(stats);
4543 
4544   // We have completed copying any necessary live referent objects.
4545   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4546 
4547   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4548   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4549 }
4550 
4551 // Weak Reference processing during an evacuation pause (part 2).
4552 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4553   double ref_enq_start = os::elapsedTime();
4554 
4555   ReferenceProcessor* rp = _ref_processor_stw;
4556   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4557 
4558   // Now enqueue any remaining on the discovered lists on to
4559   // the pending list.
4560   if (!rp->processing_is_mt()) {
4561     // Serial reference processing...
4562     rp->enqueue_discovered_references();
4563   } else {
4564     // Parallel reference enqueueing
4565 
4566     uint n_workers = workers()->active_workers();
4567 
4568     assert(rp->num_q() == n_workers, "sanity");
4569     assert(n_workers <= rp->max_num_q(), "sanity");
4570 
4571     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4572     rp->enqueue_discovered_references(&par_task_executor);
4573   }
4574 
4575   rp->verify_no_references_recorded();
4576   assert(!rp->discovery_enabled(), "should have been disabled");
4577 
4578   // FIXME
4579   // CM's reference processing also cleans up the string and symbol tables.
4580   // Should we do that here also? We could, but it is a serial operation
4581   // and could significantly increase the pause time.
4582 
4583   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4584   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4585 }
4586 
4587 void G1CollectedHeap::pre_evacuate_collection_set() {
4588   _expand_heap_after_alloc_failure = true;
4589   _evacuation_failed = false;
4590 
4591   // Disable the hot card cache.
4592   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4593   hot_card_cache->reset_hot_cache_claimed_index();
4594   hot_card_cache->set_use_cache(false);
4595 
4596   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4597 }
4598 
4599 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4600   // Should G1EvacuationFailureALot be in effect for this GC?
4601   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4602 
4603   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4604   double start_par_time_sec = os::elapsedTime();
4605   double end_par_time_sec;
4606 
4607   {
4608     const uint n_workers = workers()->active_workers();
4609     G1RootProcessor root_processor(this, n_workers);
4610     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4611     // InitialMark needs claim bits to keep track of the marked-through CLDs.
4612     if (collector_state()->during_initial_mark_pause()) {
4613       ClassLoaderDataGraph::clear_claimed_marks();
4614     }
4615 
4616     print_termination_stats_hdr();
4617 
4618     workers()->run_task(&g1_par_task);
4619     end_par_time_sec = os::elapsedTime();
4620 
4621     // Closing the inner scope will execute the destructor
4622     // for the G1RootProcessor object. We record the current
4623     // elapsed time before closing the scope so that time
4624     // taken for the destructor is NOT included in the
4625     // reported parallel time.
4626   }
4627 
4628   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4629 
4630   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4631   phase_times->record_par_time(par_time_ms);
4632 
4633   double code_root_fixup_time_ms =
4634         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4635   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4636 }
4637 
4638 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4639   // Process any discovered reference objects - we have
4640   // to do this _before_ we retire the GC alloc regions
4641   // as we may have to copy some 'reachable' referent
4642   // objects (and their reachable sub-graphs) that were
4643   // not copied during the pause.
4644   if (g1_policy()->should_process_references()) {
4645     process_discovered_references(per_thread_states);
4646   } else {
4647     ref_processor_stw()->verify_no_references_recorded();
4648     process_weak_jni_handles();
4649   }
4650 
4651   if (G1StringDedup::is_enabled()) {
4652     double fixup_start = os::elapsedTime();
4653 
4654     G1STWIsAliveClosure is_alive(this);
4655     G1KeepAliveClosure keep_alive(this);
4656     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4657 
4658     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4659     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4660   }
4661 
4662   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4663 
4664   if (evacuation_failed()) {
4665     restore_after_evac_failure();
4666 
4667     // Reset the G1EvacuationFailureALot counters and flags
4668     // Note: the values are reset only when an actual
4669     // evacuation failure occurs.
4670     NOT_PRODUCT(reset_evacuation_should_fail();)
4671   }
4672 
4673   // Enqueue any remaining references remaining on the STW
4674   // reference processor's discovered lists. We need to do
4675   // this after the card table is cleaned (and verified) as
4676   // the act of enqueueing entries on to the pending list
4677   // will log these updates (and dirty their associated
4678   // cards). We need these updates logged to update any
4679   // RSets.
4680   if (g1_policy()->should_process_references()) {
4681     enqueue_discovered_references(per_thread_states);
4682   } else {
4683     g1_policy()->phase_times()->record_ref_enq_time(0);
4684   }
4685 
4686   _allocator->release_gc_alloc_regions(evacuation_info);
4687 
4688   per_thread_states->flush();
4689 
4690   record_obj_copy_mem_stats();
4691 
4692   _survivor_evac_stats.adjust_desired_plab_sz();
4693   _old_evac_stats.adjust_desired_plab_sz();
4694 
4695   // Reset and re-enable the hot card cache.
4696   // Note the counts for the cards in the regions in the
4697   // collection set are reset when the collection set is freed.
4698   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4699   hot_card_cache->reset_hot_cache();
4700   hot_card_cache->set_use_cache(true);
4701 
4702   purge_code_root_memory();
4703 
4704   redirty_logged_cards();
4705 #if defined(COMPILER2) || INCLUDE_JVMCI
4706   DerivedPointerTable::update_pointers();
4707 #endif
4708 }
4709 
4710 void G1CollectedHeap::record_obj_copy_mem_stats() {
4711   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4712 
4713   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4714                                                create_g1_evac_summary(&_old_evac_stats));
4715 }
4716 
4717 void G1CollectedHeap::free_region(HeapRegion* hr,
4718                                   FreeRegionList* free_list,
4719                                   bool par,
4720                                   bool locked) {
4721   assert(!hr->is_free(), "the region should not be free");
4722   assert(!hr->is_empty(), "the region should not be empty");
4723   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4724   assert(free_list != NULL, "pre-condition");
4725 
4726   if (G1VerifyBitmaps) {
4727     MemRegion mr(hr->bottom(), hr->end());
4728     concurrent_mark()->clearRangePrevBitmap(mr);
4729   }
4730 
4731   // Clear the card counts for this region.
4732   // Note: we only need to do this if the region is not young
4733   // (since we don't refine cards in young regions).
4734   if (!hr->is_young()) {
4735     _cg1r->hot_card_cache()->reset_card_counts(hr);
4736   }
4737   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
4738   free_list->add_ordered(hr);
4739 }
4740 
4741 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4742                                             FreeRegionList* free_list,
4743                                             bool par) {
4744   assert(hr->is_humongous(), "this is only for humongous regions");
4745   assert(free_list != NULL, "pre-condition");
4746   hr->clear_humongous();
4747   free_region(hr, free_list, par);
4748 }
4749 
4750 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4751                                            const uint humongous_regions_removed) {
4752   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4753     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4754     _old_set.bulk_remove(old_regions_removed);
4755     _humongous_set.bulk_remove(humongous_regions_removed);
4756   }
4757 
4758 }
4759 
4760 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4761   assert(list != NULL, "list can't be null");
4762   if (!list->is_empty()) {
4763     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4764     _hrm.insert_list_into_free_list(list);
4765   }
4766 }
4767 
4768 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4769   decrease_used(bytes);
4770 }
4771 
4772 class G1ParCleanupCTTask : public AbstractGangTask {
4773   G1SATBCardTableModRefBS* _ct_bs;
4774   G1CollectedHeap* _g1h;
4775   HeapRegion* volatile _su_head;
4776 public:
4777   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
4778                      G1CollectedHeap* g1h) :
4779     AbstractGangTask("G1 Par Cleanup CT Task"),
4780     _ct_bs(ct_bs), _g1h(g1h) { }
4781 
4782   void work(uint worker_id) {
4783     HeapRegion* r;
4784     while (r = _g1h->pop_dirty_cards_region()) {
4785       clear_cards(r);
4786     }
4787   }
4788 
4789   void clear_cards(HeapRegion* r) {
4790     // Cards of the survivors should have already been dirtied.
4791     if (!r->is_survivor()) {
4792       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4793     }
4794   }
4795 };
4796 
4797 class G1ParScrubRemSetTask: public AbstractGangTask {
4798 protected:
4799   G1RemSet* _g1rs;
4800   BitMap* _region_bm;
4801   BitMap* _card_bm;
4802   HeapRegionClaimer _hrclaimer;
4803 
4804 public:
4805   G1ParScrubRemSetTask(G1RemSet* g1_rs, BitMap* region_bm, BitMap* card_bm, uint num_workers) :
4806     AbstractGangTask("G1 ScrubRS"),
4807     _g1rs(g1_rs),
4808     _region_bm(region_bm),
4809     _card_bm(card_bm),
4810     _hrclaimer(num_workers) {
4811   }
4812 
4813   void work(uint worker_id) {
4814     _g1rs->scrub(_region_bm, _card_bm, worker_id, &_hrclaimer);
4815   }
4816 };
4817 
4818 void G1CollectedHeap::scrub_rem_set(BitMap* region_bm, BitMap* card_bm) {
4819   uint num_workers = workers()->active_workers();
4820   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), region_bm, card_bm, num_workers);
4821   workers()->run_task(&g1_par_scrub_rs_task);
4822 }
4823 
4824 void G1CollectedHeap::cleanUpCardTable() {
4825   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
4826   double start = os::elapsedTime();
4827 
4828   {
4829     // Iterate over the dirty cards region list.
4830     G1ParCleanupCTTask cleanup_task(ct_bs, this);
4831 
4832     workers()->run_task(&cleanup_task);
4833 #ifndef PRODUCT
4834     _verifier->verify_card_table_cleanup();
4835 #endif
4836   }
4837 
4838   double elapsed = os::elapsedTime() - start;
4839   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
4840 }
4841 
4842 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4843   size_t pre_used = 0;
4844   FreeRegionList local_free_list("Local List for CSet Freeing");
4845 
4846   double young_time_ms     = 0.0;
4847   double non_young_time_ms = 0.0;
4848 
4849   // Since the collection set is a superset of the the young list,
4850   // all we need to do to clear the young list is clear its
4851   // head and length, and unlink any young regions in the code below
4852   _young_list->clear();
4853 
4854   G1CollectorPolicy* policy = g1_policy();
4855 
4856   double start_sec = os::elapsedTime();
4857   bool non_young = true;
4858 
4859   HeapRegion* cur = cs_head;
4860   int age_bound = -1;
4861   size_t rs_lengths = 0;
4862 
4863   while (cur != NULL) {
4864     assert(!is_on_master_free_list(cur), "sanity");
4865     if (non_young) {
4866       if (cur->is_young()) {
4867         double end_sec = os::elapsedTime();
4868         double elapsed_ms = (end_sec - start_sec) * 1000.0;
4869         non_young_time_ms += elapsed_ms;
4870 
4871         start_sec = os::elapsedTime();
4872         non_young = false;
4873       }
4874     } else {
4875       if (!cur->is_young()) {
4876         double end_sec = os::elapsedTime();
4877         double elapsed_ms = (end_sec - start_sec) * 1000.0;
4878         young_time_ms += elapsed_ms;
4879 
4880         start_sec = os::elapsedTime();
4881         non_young = true;
4882       }
4883     }
4884 
4885     rs_lengths += cur->rem_set()->occupied_locked();
4886 
4887     HeapRegion* next = cur->next_in_collection_set();
4888     assert(cur->in_collection_set(), "bad CS");
4889     cur->set_next_in_collection_set(NULL);
4890     clear_in_cset(cur);
4891 
4892     if (cur->is_young()) {
4893       int index = cur->young_index_in_cset();
4894       assert(index != -1, "invariant");
4895       assert((uint) index < collection_set()->young_region_length(), "invariant");
4896       size_t words_survived = surviving_young_words[index];
4897       cur->record_surv_words_in_group(words_survived);
4898 
4899       // At this point the we have 'popped' cur from the collection set
4900       // (linked via next_in_collection_set()) but it is still in the
4901       // young list (linked via next_young_region()). Clear the
4902       // _next_young_region field.
4903       cur->set_next_young_region(NULL);
4904     } else {
4905       int index = cur->young_index_in_cset();
4906       assert(index == -1, "invariant");
4907     }
4908 
4909     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4910             (!cur->is_young() && cur->young_index_in_cset() == -1),
4911             "invariant" );
4912 
4913     if (!cur->evacuation_failed()) {
4914       MemRegion used_mr = cur->used_region();
4915 
4916       // And the region is empty.
4917       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
4918       pre_used += cur->used();
4919       free_region(cur, &local_free_list, false /* par */, true /* locked */);
4920     } else {
4921       cur->uninstall_surv_rate_group();
4922       if (cur->is_young()) {
4923         cur->set_young_index_in_cset(-1);
4924       }
4925       cur->set_evacuation_failed(false);
4926       // When moving a young gen region to old gen, we "allocate" that whole region
4927       // there. This is in addition to any already evacuated objects. Notify the
4928       // policy about that.
4929       // Old gen regions do not cause an additional allocation: both the objects
4930       // still in the region and the ones already moved are accounted for elsewhere.
4931       if (cur->is_young()) {
4932         policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
4933       }
4934       // The region is now considered to be old.
4935       cur->set_old();
4936       // Do some allocation statistics accounting. Regions that failed evacuation
4937       // are always made old, so there is no need to update anything in the young
4938       // gen statistics, but we need to update old gen statistics.
4939       size_t used_words = cur->marked_bytes() / HeapWordSize;
4940       _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
4941       _old_set.add(cur);
4942       evacuation_info.increment_collectionset_used_after(cur->used());
4943     }
4944     cur = next;
4945   }
4946 
4947   evacuation_info.set_regions_freed(local_free_list.length());
4948   policy->record_max_rs_lengths(rs_lengths);
4949   policy->cset_regions_freed();
4950 
4951   double end_sec = os::elapsedTime();
4952   double elapsed_ms = (end_sec - start_sec) * 1000.0;
4953 
4954   if (non_young) {
4955     non_young_time_ms += elapsed_ms;
4956   } else {
4957     young_time_ms += elapsed_ms;
4958   }
4959 
4960   prepend_to_freelist(&local_free_list);
4961   decrement_summary_bytes(pre_used);
4962   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
4963   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
4964 }
4965 
4966 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4967  private:
4968   FreeRegionList* _free_region_list;
4969   HeapRegionSet* _proxy_set;
4970   uint _humongous_regions_removed;
4971   size_t _freed_bytes;
4972  public:
4973 
4974   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4975     _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4976   }
4977 
4978   virtual bool doHeapRegion(HeapRegion* r) {
4979     if (!r->is_starts_humongous()) {
4980       return false;
4981     }
4982 
4983     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4984 
4985     oop obj = (oop)r->bottom();
4986     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4987 
4988     // The following checks whether the humongous object is live are sufficient.
4989     // The main additional check (in addition to having a reference from the roots
4990     // or the young gen) is whether the humongous object has a remembered set entry.
4991     //
4992     // A humongous object cannot be live if there is no remembered set for it
4993     // because:
4994     // - there can be no references from within humongous starts regions referencing
4995     // the object because we never allocate other objects into them.
4996     // (I.e. there are no intra-region references that may be missed by the
4997     // remembered set)
4998     // - as soon there is a remembered set entry to the humongous starts region
4999     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5000     // until the end of a concurrent mark.
5001     //
5002     // It is not required to check whether the object has been found dead by marking
5003     // or not, in fact it would prevent reclamation within a concurrent cycle, as
5004     // all objects allocated during that time are considered live.
5005     // SATB marking is even more conservative than the remembered set.
5006     // So if at this point in the collection there is no remembered set entry,
5007     // nobody has a reference to it.
5008     // At the start of collection we flush all refinement logs, and remembered sets
5009     // are completely up-to-date wrt to references to the humongous object.
5010     //
5011     // Other implementation considerations:
5012     // - never consider object arrays at this time because they would pose
5013     // considerable effort for cleaning up the the remembered sets. This is
5014     // required because stale remembered sets might reference locations that
5015     // are currently allocated into.
5016     uint region_idx = r->hrm_index();
5017     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5018         !r->rem_set()->is_empty()) {
5019       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",
5020                                region_idx,
5021                                (size_t)obj->size() * HeapWordSize,
5022                                p2i(r->bottom()),
5023                                r->rem_set()->occupied(),
5024                                r->rem_set()->strong_code_roots_list_length(),
5025                                next_bitmap->isMarked(r->bottom()),
5026                                g1h->is_humongous_reclaim_candidate(region_idx),
5027                                obj->is_typeArray()
5028                               );
5029       return false;
5030     }
5031 
5032     guarantee(obj->is_typeArray(),
5033               "Only eagerly reclaiming type arrays is supported, but the object "
5034               PTR_FORMAT " is not.", p2i(r->bottom()));
5035 
5036     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",
5037                              region_idx,
5038                              (size_t)obj->size() * HeapWordSize,
5039                              p2i(r->bottom()),
5040                              r->rem_set()->occupied(),
5041                              r->rem_set()->strong_code_roots_list_length(),
5042                              next_bitmap->isMarked(r->bottom()),
5043                              g1h->is_humongous_reclaim_candidate(region_idx),
5044                              obj->is_typeArray()
5045                             );
5046 
5047     // Need to clear mark bit of the humongous object if already set.
5048     if (next_bitmap->isMarked(r->bottom())) {
5049       next_bitmap->clear(r->bottom());
5050     }
5051     do {
5052       HeapRegion* next = g1h->next_region_in_humongous(r);
5053       _freed_bytes += r->used();
5054       r->set_containing_set(NULL);
5055       _humongous_regions_removed++;
5056       g1h->free_humongous_region(r, _free_region_list, false);
5057       r = next;
5058     } while (r != NULL);
5059 
5060     return false;
5061   }
5062 
5063   uint humongous_free_count() {
5064     return _humongous_regions_removed;
5065   }
5066 
5067   size_t bytes_freed() const {
5068     return _freed_bytes;
5069   }
5070 };
5071 
5072 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5073   assert_at_safepoint(true);
5074 
5075   if (!G1EagerReclaimHumongousObjects ||
5076       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5077     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5078     return;
5079   }
5080 
5081   double start_time = os::elapsedTime();
5082 
5083   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5084 
5085   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5086   heap_region_iterate(&cl);
5087 
5088   remove_from_old_sets(0, cl.humongous_free_count());
5089 
5090   G1HRPrinter* hrp = hr_printer();
5091   if (hrp->is_active()) {
5092     FreeRegionListIterator iter(&local_cleanup_list);
5093     while (iter.more_available()) {
5094       HeapRegion* hr = iter.get_next();
5095       hrp->cleanup(hr);
5096     }
5097   }
5098 
5099   prepend_to_freelist(&local_cleanup_list);
5100   decrement_summary_bytes(cl.bytes_freed());
5101 
5102   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5103                                                                     cl.humongous_free_count());
5104 }
5105 
5106 // This routine is similar to the above but does not record
5107 // any policy statistics or update free lists; we are abandoning
5108 // the current incremental collection set in preparation of a
5109 // full collection. After the full GC we will start to build up
5110 // the incremental collection set again.
5111 // This is only called when we're doing a full collection
5112 // and is immediately followed by the tearing down of the young list.
5113 
5114 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5115   HeapRegion* cur = cs_head;
5116 
5117   while (cur != NULL) {
5118     HeapRegion* next = cur->next_in_collection_set();
5119     assert(cur->in_collection_set(), "bad CS");
5120     cur->set_next_in_collection_set(NULL);
5121     clear_in_cset(cur);
5122     cur->set_young_index_in_cset(-1);
5123     cur = next;
5124   }
5125 }
5126 
5127 void G1CollectedHeap::set_free_regions_coming() {
5128   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5129 
5130   assert(!free_regions_coming(), "pre-condition");
5131   _free_regions_coming = true;
5132 }
5133 
5134 void G1CollectedHeap::reset_free_regions_coming() {
5135   assert(free_regions_coming(), "pre-condition");
5136 
5137   {
5138     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5139     _free_regions_coming = false;
5140     SecondaryFreeList_lock->notify_all();
5141   }
5142 
5143   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5144 }
5145 
5146 void G1CollectedHeap::wait_while_free_regions_coming() {
5147   // Most of the time we won't have to wait, so let's do a quick test
5148   // first before we take the lock.
5149   if (!free_regions_coming()) {
5150     return;
5151   }
5152 
5153   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5154 
5155   {
5156     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5157     while (free_regions_coming()) {
5158       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5159     }
5160   }
5161 
5162   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5163 }
5164 
5165 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5166   return _allocator->is_retained_old_region(hr);
5167 }
5168 
5169 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5170   _young_list->push_region(hr);
5171 }
5172 
5173 class NoYoungRegionsClosure: public HeapRegionClosure {
5174 private:
5175   bool _success;
5176 public:
5177   NoYoungRegionsClosure() : _success(true) { }
5178   bool doHeapRegion(HeapRegion* r) {
5179     if (r->is_young()) {
5180       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5181                             p2i(r->bottom()), p2i(r->end()));
5182       _success = false;
5183     }
5184     return false;
5185   }
5186   bool success() { return _success; }
5187 };
5188 
5189 bool G1CollectedHeap::check_young_list_empty(bool check_heap) {
5190   bool ret = _young_list->check_list_empty();
5191 
5192   if (check_heap) {
5193     NoYoungRegionsClosure closure;
5194     heap_region_iterate(&closure);
5195     ret = ret && closure.success();
5196   }
5197 
5198   return ret;
5199 }
5200 
5201 class TearDownRegionSetsClosure : public HeapRegionClosure {
5202 private:
5203   HeapRegionSet *_old_set;
5204 
5205 public:
5206   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5207 
5208   bool doHeapRegion(HeapRegion* r) {
5209     if (r->is_old()) {
5210       _old_set->remove(r);
5211     } else {
5212       // We ignore free regions, we'll empty the free list afterwards.
5213       // We ignore young regions, we'll empty the young list afterwards.
5214       // We ignore humongous regions, we're not tearing down the
5215       // humongous regions set.
5216       assert(r->is_free() || r->is_young() || r->is_humongous(),
5217              "it cannot be another type");
5218     }
5219     return false;
5220   }
5221 
5222   ~TearDownRegionSetsClosure() {
5223     assert(_old_set->is_empty(), "post-condition");
5224   }
5225 };
5226 
5227 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5228   assert_at_safepoint(true /* should_be_vm_thread */);
5229 
5230   if (!free_list_only) {
5231     TearDownRegionSetsClosure cl(&_old_set);
5232     heap_region_iterate(&cl);
5233 
5234     // Note that emptying the _young_list is postponed and instead done as
5235     // the first step when rebuilding the regions sets again. The reason for
5236     // this is that during a full GC string deduplication needs to know if
5237     // a collected region was young or old when the full GC was initiated.
5238   }
5239   _hrm.remove_all_free_regions();
5240 }
5241 
5242 void G1CollectedHeap::increase_used(size_t bytes) {
5243   _summary_bytes_used += bytes;
5244 }
5245 
5246 void G1CollectedHeap::decrease_used(size_t bytes) {
5247   assert(_summary_bytes_used >= bytes,
5248          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5249          _summary_bytes_used, bytes);
5250   _summary_bytes_used -= bytes;
5251 }
5252 
5253 void G1CollectedHeap::set_used(size_t bytes) {
5254   _summary_bytes_used = bytes;
5255 }
5256 
5257 class RebuildRegionSetsClosure : public HeapRegionClosure {
5258 private:
5259   bool            _free_list_only;
5260   HeapRegionSet*   _old_set;
5261   HeapRegionManager*   _hrm;
5262   size_t          _total_used;
5263 
5264 public:
5265   RebuildRegionSetsClosure(bool free_list_only,
5266                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5267     _free_list_only(free_list_only),
5268     _old_set(old_set), _hrm(hrm), _total_used(0) {
5269     assert(_hrm->num_free_regions() == 0, "pre-condition");
5270     if (!free_list_only) {
5271       assert(_old_set->is_empty(), "pre-condition");
5272     }
5273   }
5274 
5275   bool doHeapRegion(HeapRegion* r) {
5276     if (r->is_empty()) {
5277       // Add free regions to the free list
5278       r->set_free();
5279       r->set_allocation_context(AllocationContext::system());
5280       _hrm->insert_into_free_list(r);
5281     } else if (!_free_list_only) {
5282       assert(!r->is_young(), "we should not come across young regions");
5283 
5284       if (r->is_humongous()) {
5285         // We ignore humongous regions. We left the humongous set unchanged.
5286       } else {
5287         // Objects that were compacted would have ended up on regions
5288         // that were previously old or free.  Archive regions (which are
5289         // old) will not have been touched.
5290         assert(r->is_free() || r->is_old(), "invariant");
5291         // We now consider them old, so register as such. Leave
5292         // archive regions set that way, however, while still adding
5293         // them to the old set.
5294         if (!r->is_archive()) {
5295           r->set_old();
5296         }
5297         _old_set->add(r);
5298       }
5299       _total_used += r->used();
5300     }
5301 
5302     return false;
5303   }
5304 
5305   size_t total_used() {
5306     return _total_used;
5307   }
5308 };
5309 
5310 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5311   assert_at_safepoint(true /* should_be_vm_thread */);
5312 
5313   if (!free_list_only) {
5314     _young_list->empty_list();
5315   }
5316 
5317   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5318   heap_region_iterate(&cl);
5319 
5320   if (!free_list_only) {
5321     set_used(cl.total_used());
5322     if (_archive_allocator != NULL) {
5323       _archive_allocator->clear_used();
5324     }
5325   }
5326   assert(used_unlocked() == recalculate_used(),
5327          "inconsistent used_unlocked(), "
5328          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5329          used_unlocked(), recalculate_used());
5330 }
5331 
5332 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5333   _refine_cte_cl->set_concurrent(concurrent);
5334 }
5335 
5336 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5337   HeapRegion* hr = heap_region_containing(p);
5338   return hr->is_in(p);
5339 }
5340 
5341 // Methods for the mutator alloc region
5342 
5343 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5344                                                       bool force) {
5345   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5346   assert(!force || g1_policy()->can_expand_young_list(),
5347          "if force is true we should be able to expand the young list");
5348   bool young_list_full = g1_policy()->is_young_list_full();
5349   if (force || !young_list_full) {
5350     HeapRegion* new_alloc_region = new_region(word_size,
5351                                               false /* is_old */,
5352                                               false /* do_expand */);
5353     if (new_alloc_region != NULL) {
5354       set_region_short_lived_locked(new_alloc_region);
5355       _hr_printer.alloc(new_alloc_region, young_list_full);
5356       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5357       return new_alloc_region;
5358     }
5359   }
5360   return NULL;
5361 }
5362 
5363 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5364                                                   size_t allocated_bytes) {
5365   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5366   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5367 
5368   collection_set()->add_eden_region(alloc_region);
5369   increase_used(allocated_bytes);
5370   _hr_printer.retire(alloc_region);
5371   // We update the eden sizes here, when the region is retired,
5372   // instead of when it's allocated, since this is the point that its
5373   // used space has been recored in _summary_bytes_used.
5374   g1mm()->update_eden_size();
5375 }
5376 
5377 // Methods for the GC alloc regions
5378 
5379 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
5380                                                  uint count,
5381                                                  InCSetState dest) {
5382   assert(FreeList_lock->owned_by_self(), "pre-condition");
5383 
5384   if (count < g1_policy()->max_regions(dest)) {
5385     const bool is_survivor = (dest.is_young());
5386     HeapRegion* new_alloc_region = new_region(word_size,
5387                                               !is_survivor,
5388                                               true /* do_expand */);
5389     if (new_alloc_region != NULL) {
5390       // We really only need to do this for old regions given that we
5391       // should never scan survivors. But it doesn't hurt to do it
5392       // for survivors too.
5393       new_alloc_region->record_timestamp();
5394       if (is_survivor) {
5395         new_alloc_region->set_survivor();
5396         _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5397       } else {
5398         new_alloc_region->set_old();
5399         _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5400       }
5401       _hr_printer.alloc(new_alloc_region);
5402       bool during_im = collector_state()->during_initial_mark_pause();
5403       new_alloc_region->note_start_of_copying(during_im);
5404       return new_alloc_region;
5405     }
5406   }
5407   return NULL;
5408 }
5409 
5410 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5411                                              size_t allocated_bytes,
5412                                              InCSetState dest) {
5413   bool during_im = collector_state()->during_initial_mark_pause();
5414   alloc_region->note_end_of_copying(during_im);
5415   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5416   if (dest.is_young()) {
5417     young_list()->add_survivor_region(alloc_region);
5418   } else {
5419     _old_set.add(alloc_region);
5420   }
5421   _hr_printer.retire(alloc_region);
5422 }
5423 
5424 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5425   bool expanded = false;
5426   uint index = _hrm.find_highest_free(&expanded);
5427 
5428   if (index != G1_NO_HRM_INDEX) {
5429     if (expanded) {
5430       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5431                                 HeapRegion::GrainWords * HeapWordSize);
5432     }
5433     _hrm.allocate_free_regions_starting_at(index, 1);
5434     return region_at(index);
5435   }
5436   return NULL;
5437 }
5438 
5439 // Optimized nmethod scanning
5440 
5441 class RegisterNMethodOopClosure: public OopClosure {
5442   G1CollectedHeap* _g1h;
5443   nmethod* _nm;
5444 
5445   template <class T> void do_oop_work(T* p) {
5446     T heap_oop = oopDesc::load_heap_oop(p);
5447     if (!oopDesc::is_null(heap_oop)) {
5448       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5449       HeapRegion* hr = _g1h->heap_region_containing(obj);
5450       assert(!hr->is_continues_humongous(),
5451              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5452              " starting at " HR_FORMAT,
5453              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5454 
5455       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5456       hr->add_strong_code_root_locked(_nm);
5457     }
5458   }
5459 
5460 public:
5461   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5462     _g1h(g1h), _nm(nm) {}
5463 
5464   void do_oop(oop* p)       { do_oop_work(p); }
5465   void do_oop(narrowOop* p) { do_oop_work(p); }
5466 };
5467 
5468 class UnregisterNMethodOopClosure: public OopClosure {
5469   G1CollectedHeap* _g1h;
5470   nmethod* _nm;
5471 
5472   template <class T> void do_oop_work(T* p) {
5473     T heap_oop = oopDesc::load_heap_oop(p);
5474     if (!oopDesc::is_null(heap_oop)) {
5475       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5476       HeapRegion* hr = _g1h->heap_region_containing(obj);
5477       assert(!hr->is_continues_humongous(),
5478              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5479              " starting at " HR_FORMAT,
5480              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5481 
5482       hr->remove_strong_code_root(_nm);
5483     }
5484   }
5485 
5486 public:
5487   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5488     _g1h(g1h), _nm(nm) {}
5489 
5490   void do_oop(oop* p)       { do_oop_work(p); }
5491   void do_oop(narrowOop* p) { do_oop_work(p); }
5492 };
5493 
5494 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5495   CollectedHeap::register_nmethod(nm);
5496 
5497   guarantee(nm != NULL, "sanity");
5498   RegisterNMethodOopClosure reg_cl(this, nm);
5499   nm->oops_do(&reg_cl);
5500 }
5501 
5502 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5503   CollectedHeap::unregister_nmethod(nm);
5504 
5505   guarantee(nm != NULL, "sanity");
5506   UnregisterNMethodOopClosure reg_cl(this, nm);
5507   nm->oops_do(&reg_cl, true);
5508 }
5509 
5510 void G1CollectedHeap::purge_code_root_memory() {
5511   double purge_start = os::elapsedTime();
5512   G1CodeRootSet::purge();
5513   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5514   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5515 }
5516 
5517 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5518   G1CollectedHeap* _g1h;
5519 
5520 public:
5521   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5522     _g1h(g1h) {}
5523 
5524   void do_code_blob(CodeBlob* cb) {
5525     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5526     if (nm == NULL) {
5527       return;
5528     }
5529 
5530     if (ScavengeRootsInCode) {
5531       _g1h->register_nmethod(nm);
5532     }
5533   }
5534 };
5535 
5536 void G1CollectedHeap::rebuild_strong_code_roots() {
5537   RebuildStrongCodeRootClosure blob_cl(this);
5538   CodeCache::blobs_do(&blob_cl);
5539 }