1 /*
   2  * Copyright (c) 2001, 2019, 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/classLoaderDataGraph.hpp"
  27 #include "classfile/metadataOnStackMark.hpp"
  28 #include "classfile/stringTable.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "gc/g1/g1Allocator.inline.hpp"
  32 #include "gc/g1/g1Arguments.hpp"
  33 #include "gc/g1/g1BarrierSet.hpp"
  34 #include "gc/g1/g1CardTableEntryClosure.hpp"
  35 #include "gc/g1/g1CollectedHeap.inline.hpp"
  36 #include "gc/g1/g1CollectionSet.hpp"
  37 #include "gc/g1/g1CollectorState.hpp"
  38 #include "gc/g1/g1ConcurrentRefine.hpp"
  39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
  40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
  41 #include "gc/g1/g1DirtyCardQueue.hpp"
  42 #include "gc/g1/g1EvacStats.inline.hpp"
  43 #include "gc/g1/g1FullCollector.hpp"
  44 #include "gc/g1/g1GCPhaseTimes.hpp"
  45 #include "gc/g1/g1HeapSizingPolicy.hpp"
  46 #include "gc/g1/g1HeapTransition.hpp"
  47 #include "gc/g1/g1HeapVerifier.hpp"
  48 #include "gc/g1/g1HotCardCache.hpp"
  49 #include "gc/g1/g1MemoryPool.hpp"
  50 #include "gc/g1/g1OopClosures.inline.hpp"
  51 #include "gc/g1/g1ParallelCleaning.hpp"
  52 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  53 #include "gc/g1/g1Policy.hpp"
  54 #include "gc/g1/g1RedirtyCardsQueue.hpp"
  55 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  56 #include "gc/g1/g1RemSet.hpp"
  57 #include "gc/g1/g1RootClosures.hpp"
  58 #include "gc/g1/g1RootProcessor.hpp"
  59 #include "gc/g1/g1SATBMarkQueueSet.hpp"
  60 #include "gc/g1/g1StringDedup.hpp"
  61 #include "gc/g1/g1ThreadLocalData.hpp"
  62 #include "gc/g1/g1YCTypes.hpp"
  63 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  64 #include "gc/g1/g1VMOperations.hpp"
  65 #include "gc/g1/heapRegion.inline.hpp"
  66 #include "gc/g1/heapRegionRemSet.hpp"
  67 #include "gc/g1/heapRegionSet.inline.hpp"
  68 #include "gc/shared/gcBehaviours.hpp"
  69 #include "gc/shared/gcHeapSummary.hpp"
  70 #include "gc/shared/gcId.hpp"
  71 #include "gc/shared/gcLocker.hpp"
  72 #include "gc/shared/gcTimer.hpp"
  73 #include "gc/shared/gcTrace.hpp"
  74 #include "gc/shared/gcTraceTime.inline.hpp"
  75 #include "gc/shared/generationSpec.hpp"
  76 #include "gc/shared/isGCActiveMark.hpp"
  77 #include "gc/shared/oopStorageParState.hpp"
  78 #include "gc/shared/preservedMarks.inline.hpp"
  79 #include "gc/shared/suspendibleThreadSet.hpp"
  80 #include "gc/shared/referenceProcessor.inline.hpp"
  81 #include "gc/shared/taskqueue.inline.hpp"
  82 #include "gc/shared/weakProcessor.inline.hpp"
  83 #include "gc/shared/workerPolicy.hpp"
  84 #include "logging/log.hpp"
  85 #include "memory/allocation.hpp"
  86 #include "memory/iterator.hpp"
  87 #include "memory/resourceArea.hpp"
  88 #include "memory/universe.hpp"
  89 #include "oops/access.inline.hpp"
  90 #include "oops/compressedOops.inline.hpp"
  91 #include "oops/oop.inline.hpp"
  92 #include "runtime/atomic.hpp"
  93 #include "runtime/flags/flagSetting.hpp"
  94 #include "runtime/handles.inline.hpp"
  95 #include "runtime/init.hpp"
  96 #include "runtime/orderAccess.hpp"
  97 #include "runtime/threadSMR.hpp"
  98 #include "runtime/vmThread.hpp"
  99 #include "utilities/align.hpp"
 100 #include "utilities/globalDefinitions.hpp"
 101 #include "utilities/stack.inline.hpp"
 102 
 103 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
 104 
 105 // INVARIANTS/NOTES
 106 //
 107 // All allocation activity covered by the G1CollectedHeap interface is
 108 // serialized by acquiring the HeapLock.  This happens in mem_allocate
 109 // and allocate_new_tlab, which are the "entry" points to the
 110 // allocation code from the rest of the JVM.  (Note that this does not
 111 // apply to TLAB allocation, which is not part of this interface: it
 112 // is done by clients of this interface.)
 113 
 114 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
 115  private:
 116   size_t _num_dirtied;
 117   G1CollectedHeap* _g1h;
 118   G1CardTable* _g1_ct;
 119 
 120   HeapRegion* region_for_card(CardValue* card_ptr) const {
 121     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
 122   }
 123 
 124   bool will_become_free(HeapRegion* hr) const {
 125     // A region will be freed by free_collection_set if the region is in the
 126     // collection set and has not had an evacuation failure.
 127     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 128   }
 129 
 130  public:
 131   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
 132     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
 133 
 134   bool do_card_ptr(CardValue* card_ptr, uint worker_i) {
 135     HeapRegion* hr = region_for_card(card_ptr);
 136 
 137     // Should only dirty cards in regions that won't be freed.
 138     if (!will_become_free(hr)) {
 139       *card_ptr = G1CardTable::dirty_card_val();
 140       _num_dirtied++;
 141     }
 142 
 143     return true;
 144   }
 145 
 146   size_t num_dirtied()   const { return _num_dirtied; }
 147 };
 148 
 149 
 150 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 151   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 152 }
 153 
 154 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 155   // The from card cache is not the memory that is actually committed. So we cannot
 156   // take advantage of the zero_filled parameter.
 157   reset_from_card_cache(start_idx, num_regions);
 158 }
 159 
 160 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
 161   Ticks start = Ticks::now();
 162   workers()->run_task(task, workers()->active_workers());
 163   return Ticks::now() - start;
 164 }
 165 
 166 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 167                                              MemRegion mr) {
 168   return new HeapRegion(hrs_index, bot(), mr);
 169 }
 170 
 171 // Private methods.
 172 
 173 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) {
 174   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 175          "the only time we use this to allocate a humongous region is "
 176          "when we are allocating a single humongous region");
 177 
 178   HeapRegion* res = _hrm->allocate_free_region(type);
 179 
 180   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 181     // Currently, only attempts to allocate GC alloc regions set
 182     // do_expand to true. So, we should only reach here during a
 183     // safepoint. If this assumption changes we might have to
 184     // reconsider the use of _expand_heap_after_alloc_failure.
 185     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 186 
 187     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 188                               word_size * HeapWordSize);
 189 
 190     if (expand(word_size * HeapWordSize)) {
 191       // Given that expand() succeeded in expanding the heap, and we
 192       // always expand the heap by an amount aligned to the heap
 193       // region size, the free list should in theory not be empty.
 194       // In either case allocate_free_region() will check for NULL.
 195       res = _hrm->allocate_free_region(type);
 196     } else {
 197       _expand_heap_after_alloc_failure = false;
 198     }
 199   }
 200   return res;
 201 }
 202 
 203 HeapWord*
 204 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 205                                                            uint num_regions,
 206                                                            size_t word_size) {
 207   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 208   assert(is_humongous(word_size), "word_size should be humongous");
 209   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 210 
 211   // Index of last region in the series.
 212   uint last = first + num_regions - 1;
 213 
 214   // We need to initialize the region(s) we just discovered. This is
 215   // a bit tricky given that it can happen concurrently with
 216   // refinement threads refining cards on these regions and
 217   // potentially wanting to refine the BOT as they are scanning
 218   // those cards (this can happen shortly after a cleanup; see CR
 219   // 6991377). So we have to set up the region(s) carefully and in
 220   // a specific order.
 221 
 222   // The word size sum of all the regions we will allocate.
 223   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 224   assert(word_size <= word_size_sum, "sanity");
 225 
 226   // This will be the "starts humongous" region.
 227   HeapRegion* first_hr = region_at(first);
 228   // The header of the new object will be placed at the bottom of
 229   // the first region.
 230   HeapWord* new_obj = first_hr->bottom();
 231   // This will be the new top of the new object.
 232   HeapWord* obj_top = new_obj + word_size;
 233 
 234   // First, we need to zero the header of the space that we will be
 235   // allocating. When we update top further down, some refinement
 236   // threads might try to scan the region. By zeroing the header we
 237   // ensure that any thread that will try to scan the region will
 238   // come across the zero klass word and bail out.
 239   //
 240   // NOTE: It would not have been correct to have used
 241   // CollectedHeap::fill_with_object() and make the space look like
 242   // an int array. The thread that is doing the allocation will
 243   // later update the object header to a potentially different array
 244   // type and, for a very short period of time, the klass and length
 245   // fields will be inconsistent. This could cause a refinement
 246   // thread to calculate the object size incorrectly.
 247   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 248 
 249   // Next, pad out the unused tail of the last region with filler
 250   // objects, for improved usage accounting.
 251   // How many words we use for filler objects.
 252   size_t word_fill_size = word_size_sum - word_size;
 253 
 254   // How many words memory we "waste" which cannot hold a filler object.
 255   size_t words_not_fillable = 0;
 256 
 257   if (word_fill_size >= min_fill_size()) {
 258     fill_with_objects(obj_top, word_fill_size);
 259   } else if (word_fill_size > 0) {
 260     // We have space to fill, but we cannot fit an object there.
 261     words_not_fillable = word_fill_size;
 262     word_fill_size = 0;
 263   }
 264 
 265   // We will set up the first region as "starts humongous". This
 266   // will also update the BOT covering all the regions to reflect
 267   // that there is a single object that starts at the bottom of the
 268   // first region.
 269   first_hr->set_starts_humongous(obj_top, word_fill_size);
 270   _policy->remset_tracker()->update_at_allocate(first_hr);
 271   // Then, if there are any, we will set up the "continues
 272   // humongous" regions.
 273   HeapRegion* hr = NULL;
 274   for (uint i = first + 1; i <= last; ++i) {
 275     hr = region_at(i);
 276     hr->set_continues_humongous(first_hr);
 277     _policy->remset_tracker()->update_at_allocate(hr);
 278   }
 279 
 280   // Up to this point no concurrent thread would have been able to
 281   // do any scanning on any region in this series. All the top
 282   // fields still point to bottom, so the intersection between
 283   // [bottom,top] and [card_start,card_end] will be empty. Before we
 284   // update the top fields, we'll do a storestore to make sure that
 285   // no thread sees the update to top before the zeroing of the
 286   // object header and the BOT initialization.
 287   OrderAccess::storestore();
 288 
 289   // Now, we will update the top fields of the "continues humongous"
 290   // regions except the last one.
 291   for (uint i = first; i < last; ++i) {
 292     hr = region_at(i);
 293     hr->set_top(hr->end());
 294   }
 295 
 296   hr = region_at(last);
 297   // If we cannot fit a filler object, we must set top to the end
 298   // of the humongous object, otherwise we cannot iterate the heap
 299   // and the BOT will not be complete.
 300   hr->set_top(hr->end() - words_not_fillable);
 301 
 302   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 303          "obj_top should be in last region");
 304 
 305   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 306 
 307   assert(words_not_fillable == 0 ||
 308          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 309          "Miscalculation in humongous allocation");
 310 
 311   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 312 
 313   for (uint i = first; i <= last; ++i) {
 314     hr = region_at(i);
 315     _humongous_set.add(hr);
 316     _hr_printer.alloc(hr);
 317   }
 318 
 319   return new_obj;
 320 }
 321 
 322 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 323   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 324   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 325 }
 326 
 327 // If could fit into free regions w/o expansion, try.
 328 // Otherwise, if can expand, do so.
 329 // Otherwise, if using ex regions might help, try with ex given back.
 330 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 331   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 332 
 333   _verifier->verify_region_sets_optional();
 334 
 335   uint first = G1_NO_HRM_INDEX;
 336   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 337 
 338   if (obj_regions == 1) {
 339     // Only one region to allocate, try to use a fast path by directly allocating
 340     // from the free lists. Do not try to expand here, we will potentially do that
 341     // later.
 342     HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
 343     if (hr != NULL) {
 344       first = hr->hrm_index();
 345     }
 346   } else {
 347     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 348     // are lucky enough to find some.
 349     first = _hrm->find_contiguous_only_empty(obj_regions);
 350     if (first != G1_NO_HRM_INDEX) {
 351       _hrm->allocate_free_regions_starting_at(first, obj_regions);
 352     }
 353   }
 354 
 355   if (first == G1_NO_HRM_INDEX) {
 356     // Policy: We could not find enough regions for the humongous object in the
 357     // free list. Look through the heap to find a mix of free and uncommitted regions.
 358     // If so, try expansion.
 359     first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
 360     if (first != G1_NO_HRM_INDEX) {
 361       // We found something. Make sure these regions are committed, i.e. expand
 362       // the heap. Alternatively we could do a defragmentation GC.
 363       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 364                                     word_size * HeapWordSize);
 365 
 366       _hrm->expand_at(first, obj_regions, workers());
 367       policy()->record_new_heap_size(num_regions());
 368 
 369 #ifdef ASSERT
 370       for (uint i = first; i < first + obj_regions; ++i) {
 371         HeapRegion* hr = region_at(i);
 372         assert(hr->is_free(), "sanity");
 373         assert(hr->is_empty(), "sanity");
 374         assert(is_on_master_free_list(hr), "sanity");
 375       }
 376 #endif
 377       _hrm->allocate_free_regions_starting_at(first, obj_regions);
 378     } else {
 379       // Policy: Potentially trigger a defragmentation GC.
 380     }
 381   }
 382 
 383   HeapWord* result = NULL;
 384   if (first != G1_NO_HRM_INDEX) {
 385     result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
 386     assert(result != NULL, "it should always return a valid result");
 387 
 388     // A successful humongous object allocation changes the used space
 389     // information of the old generation so we need to recalculate the
 390     // sizes and update the jstat counters here.
 391     g1mm()->update_sizes();
 392   }
 393 
 394   _verifier->verify_region_sets_optional();
 395 
 396   return result;
 397 }
 398 
 399 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
 400                                              size_t requested_size,
 401                                              size_t* actual_size) {
 402   assert_heap_not_locked_and_not_at_safepoint();
 403   assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
 404 
 405   return attempt_allocation(min_size, requested_size, actual_size);
 406 }
 407 
 408 HeapWord*
 409 G1CollectedHeap::mem_allocate(size_t word_size,
 410                               bool*  gc_overhead_limit_was_exceeded) {
 411   assert_heap_not_locked_and_not_at_safepoint();
 412 
 413   if (is_humongous(word_size)) {
 414     return attempt_allocation_humongous(word_size);
 415   }
 416   size_t dummy = 0;
 417   return attempt_allocation(word_size, word_size, &dummy);
 418 }
 419 
 420 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 421   ResourceMark rm; // For retrieving the thread names in log messages.
 422 
 423   // Make sure you read the note in attempt_allocation_humongous().
 424 
 425   assert_heap_not_locked_and_not_at_safepoint();
 426   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 427          "be called for humongous allocation requests");
 428 
 429   // We should only get here after the first-level allocation attempt
 430   // (attempt_allocation()) failed to allocate.
 431 
 432   // We will loop until a) we manage to successfully perform the
 433   // allocation or b) we successfully schedule a collection which
 434   // fails to perform the allocation. b) is the only case when we'll
 435   // return NULL.
 436   HeapWord* result = NULL;
 437   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 438     bool should_try_gc;
 439     uint gc_count_before;
 440 
 441     {
 442       MutexLocker x(Heap_lock);
 443       result = _allocator->attempt_allocation_locked(word_size);
 444       if (result != NULL) {
 445         return result;
 446       }
 447 
 448       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 449       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 450       // waiting because the GCLocker is active to not wait too long.
 451       if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
 452         // No need for an ergo message here, can_expand_young_list() does this when
 453         // it returns true.
 454         result = _allocator->attempt_allocation_force(word_size);
 455         if (result != NULL) {
 456           return result;
 457         }
 458       }
 459       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 460       // the GCLocker initiated GC has been performed and then retry. This includes
 461       // the case when the GC Locker is not active but has not been performed.
 462       should_try_gc = !GCLocker::needs_gc();
 463       // Read the GC count while still holding the Heap_lock.
 464       gc_count_before = total_collections();
 465     }
 466 
 467     if (should_try_gc) {
 468       bool succeeded;
 469       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 470                                    GCCause::_g1_inc_collection_pause);
 471       if (result != NULL) {
 472         assert(succeeded, "only way to get back a non-NULL result");
 473         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 474                              Thread::current()->name(), p2i(result));
 475         return result;
 476       }
 477 
 478       if (succeeded) {
 479         // We successfully scheduled a collection which failed to allocate. No
 480         // point in trying to allocate further. We'll just return NULL.
 481         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 482                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 483         return NULL;
 484       }
 485       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 486                            Thread::current()->name(), word_size);
 487     } else {
 488       // Failed to schedule a collection.
 489       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 490         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 491                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 492         return NULL;
 493       }
 494       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 495       // The GCLocker is either active or the GCLocker initiated
 496       // GC has not yet been performed. Stall until it is and
 497       // then retry the allocation.
 498       GCLocker::stall_until_clear();
 499       gclocker_retry_count += 1;
 500     }
 501 
 502     // We can reach here if we were unsuccessful in scheduling a
 503     // collection (because another thread beat us to it) or if we were
 504     // stalled due to the GC locker. In either can we should retry the
 505     // allocation attempt in case another thread successfully
 506     // performed a collection and reclaimed enough space. We do the
 507     // first attempt (without holding the Heap_lock) here and the
 508     // follow-on attempt will be at the start of the next loop
 509     // iteration (after taking the Heap_lock).
 510     size_t dummy = 0;
 511     result = _allocator->attempt_allocation(word_size, word_size, &dummy);
 512     if (result != NULL) {
 513       return result;
 514     }
 515 
 516     // Give a warning if we seem to be looping forever.
 517     if ((QueuedAllocationWarningCount > 0) &&
 518         (try_count % QueuedAllocationWarningCount == 0)) {
 519       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 520                              Thread::current()->name(), try_count, word_size);
 521     }
 522   }
 523 
 524   ShouldNotReachHere();
 525   return NULL;
 526 }
 527 
 528 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 529   assert_at_safepoint_on_vm_thread();
 530   if (_archive_allocator == NULL) {
 531     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 532   }
 533 }
 534 
 535 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 536   // Allocations in archive regions cannot be of a size that would be considered
 537   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 538   // may be different at archive-restore time.
 539   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 540 }
 541 
 542 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 543   assert_at_safepoint_on_vm_thread();
 544   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 545   if (is_archive_alloc_too_large(word_size)) {
 546     return NULL;
 547   }
 548   return _archive_allocator->archive_mem_allocate(word_size);
 549 }
 550 
 551 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 552                                               size_t end_alignment_in_bytes) {
 553   assert_at_safepoint_on_vm_thread();
 554   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 555 
 556   // Call complete_archive to do the real work, filling in the MemRegion
 557   // array with the archive regions.
 558   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 559   delete _archive_allocator;
 560   _archive_allocator = NULL;
 561 }
 562 
 563 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 564   assert(ranges != NULL, "MemRegion array NULL");
 565   assert(count != 0, "No MemRegions provided");
 566   MemRegion reserved = _hrm->reserved();
 567   for (size_t i = 0; i < count; i++) {
 568     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 569       return false;
 570     }
 571   }
 572   return true;
 573 }
 574 
 575 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 576                                             size_t count,
 577                                             bool open) {
 578   assert(!is_init_completed(), "Expect to be called at JVM init time");
 579   assert(ranges != NULL, "MemRegion array NULL");
 580   assert(count != 0, "No MemRegions provided");
 581   MutexLocker x(Heap_lock);
 582 
 583   MemRegion reserved = _hrm->reserved();
 584   HeapWord* prev_last_addr = NULL;
 585   HeapRegion* prev_last_region = NULL;
 586 
 587   // Temporarily disable pretouching of heap pages. This interface is used
 588   // when mmap'ing archived heap data in, so pre-touching is wasted.
 589   FlagSetting fs(AlwaysPreTouch, false);
 590 
 591   // Enable archive object checking used by G1MarkSweep. We have to let it know
 592   // about each archive range, so that objects in those ranges aren't marked.
 593   G1ArchiveAllocator::enable_archive_object_check();
 594 
 595   // For each specified MemRegion range, allocate the corresponding G1
 596   // regions and mark them as archive regions. We expect the ranges
 597   // in ascending starting address order, without overlap.
 598   for (size_t i = 0; i < count; i++) {
 599     MemRegion curr_range = ranges[i];
 600     HeapWord* start_address = curr_range.start();
 601     size_t word_size = curr_range.word_size();
 602     HeapWord* last_address = curr_range.last();
 603     size_t commits = 0;
 604 
 605     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 606               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 607               p2i(start_address), p2i(last_address));
 608     guarantee(start_address > prev_last_addr,
 609               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 610               p2i(start_address), p2i(prev_last_addr));
 611     prev_last_addr = last_address;
 612 
 613     // Check for ranges that start in the same G1 region in which the previous
 614     // range ended, and adjust the start address so we don't try to allocate
 615     // the same region again. If the current range is entirely within that
 616     // region, skip it, just adjusting the recorded top.
 617     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 618     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 619       start_address = start_region->end();
 620       if (start_address > last_address) {
 621         increase_used(word_size * HeapWordSize);
 622         start_region->set_top(last_address + 1);
 623         continue;
 624       }
 625       start_region->set_top(start_address);
 626       curr_range = MemRegion(start_address, last_address + 1);
 627       start_region = _hrm->addr_to_region(start_address);
 628     }
 629 
 630     // Perform the actual region allocation, exiting if it fails.
 631     // Then note how much new space we have allocated.
 632     if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
 633       return false;
 634     }
 635     increase_used(word_size * HeapWordSize);
 636     if (commits != 0) {
 637       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 638                                 HeapRegion::GrainWords * HeapWordSize * commits);
 639 
 640     }
 641 
 642     // Mark each G1 region touched by the range as archive, add it to
 643     // the old set, and set top.
 644     HeapRegion* curr_region = _hrm->addr_to_region(start_address);
 645     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 646     prev_last_region = last_region;
 647 
 648     while (curr_region != NULL) {
 649       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 650              "Region already in use (index %u)", curr_region->hrm_index());
 651       if (open) {
 652         curr_region->set_open_archive();
 653       } else {
 654         curr_region->set_closed_archive();
 655       }
 656       _hr_printer.alloc(curr_region);
 657       _archive_set.add(curr_region);
 658       HeapWord* top;
 659       HeapRegion* next_region;
 660       if (curr_region != last_region) {
 661         top = curr_region->end();
 662         next_region = _hrm->next_region_in_heap(curr_region);
 663       } else {
 664         top = last_address + 1;
 665         next_region = NULL;
 666       }
 667       curr_region->set_top(top);
 668       curr_region->set_first_dead(top);
 669       curr_region->set_end_of_live(top);
 670       curr_region = next_region;
 671     }
 672 
 673     // Notify mark-sweep of the archive
 674     G1ArchiveAllocator::set_range_archive(curr_range, open);
 675   }
 676   return true;
 677 }
 678 
 679 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 680   assert(!is_init_completed(), "Expect to be called at JVM init time");
 681   assert(ranges != NULL, "MemRegion array NULL");
 682   assert(count != 0, "No MemRegions provided");
 683   MemRegion reserved = _hrm->reserved();
 684   HeapWord *prev_last_addr = NULL;
 685   HeapRegion* prev_last_region = NULL;
 686 
 687   // For each MemRegion, create filler objects, if needed, in the G1 regions
 688   // that contain the address range. The address range actually within the
 689   // MemRegion will not be modified. That is assumed to have been initialized
 690   // elsewhere, probably via an mmap of archived heap data.
 691   MutexLocker x(Heap_lock);
 692   for (size_t i = 0; i < count; i++) {
 693     HeapWord* start_address = ranges[i].start();
 694     HeapWord* last_address = ranges[i].last();
 695 
 696     assert(reserved.contains(start_address) && reserved.contains(last_address),
 697            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 698            p2i(start_address), p2i(last_address));
 699     assert(start_address > prev_last_addr,
 700            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 701            p2i(start_address), p2i(prev_last_addr));
 702 
 703     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 704     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 705     HeapWord* bottom_address = start_region->bottom();
 706 
 707     // Check for a range beginning in the same region in which the
 708     // previous one ended.
 709     if (start_region == prev_last_region) {
 710       bottom_address = prev_last_addr + 1;
 711     }
 712 
 713     // Verify that the regions were all marked as archive regions by
 714     // alloc_archive_regions.
 715     HeapRegion* curr_region = start_region;
 716     while (curr_region != NULL) {
 717       guarantee(curr_region->is_archive(),
 718                 "Expected archive region at index %u", curr_region->hrm_index());
 719       if (curr_region != last_region) {
 720         curr_region = _hrm->next_region_in_heap(curr_region);
 721       } else {
 722         curr_region = NULL;
 723       }
 724     }
 725 
 726     prev_last_addr = last_address;
 727     prev_last_region = last_region;
 728 
 729     // Fill the memory below the allocated range with dummy object(s),
 730     // if the region bottom does not match the range start, or if the previous
 731     // range ended within the same G1 region, and there is a gap.
 732     if (start_address != bottom_address) {
 733       size_t fill_size = pointer_delta(start_address, bottom_address);
 734       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 735       increase_used(fill_size * HeapWordSize);
 736     }
 737   }
 738 }
 739 
 740 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
 741                                                      size_t desired_word_size,
 742                                                      size_t* actual_word_size) {
 743   assert_heap_not_locked_and_not_at_safepoint();
 744   assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
 745          "be called for humongous allocation requests");
 746 
 747   HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
 748 
 749   if (result == NULL) {
 750     *actual_word_size = desired_word_size;
 751     result = attempt_allocation_slow(desired_word_size);
 752   }
 753 
 754   assert_heap_not_locked();
 755   if (result != NULL) {
 756     assert(*actual_word_size != 0, "Actual size must have been set here");
 757     dirty_young_block(result, *actual_word_size);
 758   } else {
 759     *actual_word_size = 0;
 760   }
 761 
 762   return result;
 763 }
 764 
 765 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
 766   assert(!is_init_completed(), "Expect to be called at JVM init time");
 767   assert(ranges != NULL, "MemRegion array NULL");
 768   assert(count != 0, "No MemRegions provided");
 769   MemRegion reserved = _hrm->reserved();
 770   HeapWord* prev_last_addr = NULL;
 771   HeapRegion* prev_last_region = NULL;
 772   size_t size_used = 0;
 773   size_t uncommitted_regions = 0;
 774 
 775   // For each Memregion, free the G1 regions that constitute it, and
 776   // notify mark-sweep that the range is no longer to be considered 'archive.'
 777   MutexLocker x(Heap_lock);
 778   for (size_t i = 0; i < count; i++) {
 779     HeapWord* start_address = ranges[i].start();
 780     HeapWord* last_address = ranges[i].last();
 781 
 782     assert(reserved.contains(start_address) && reserved.contains(last_address),
 783            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 784            p2i(start_address), p2i(last_address));
 785     assert(start_address > prev_last_addr,
 786            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 787            p2i(start_address), p2i(prev_last_addr));
 788     size_used += ranges[i].byte_size();
 789     prev_last_addr = last_address;
 790 
 791     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 792     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 793 
 794     // Check for ranges that start in the same G1 region in which the previous
 795     // range ended, and adjust the start address so we don't try to free
 796     // the same region again. If the current range is entirely within that
 797     // region, skip it.
 798     if (start_region == prev_last_region) {
 799       start_address = start_region->end();
 800       if (start_address > last_address) {
 801         continue;
 802       }
 803       start_region = _hrm->addr_to_region(start_address);
 804     }
 805     prev_last_region = last_region;
 806 
 807     // After verifying that each region was marked as an archive region by
 808     // alloc_archive_regions, set it free and empty and uncommit it.
 809     HeapRegion* curr_region = start_region;
 810     while (curr_region != NULL) {
 811       guarantee(curr_region->is_archive(),
 812                 "Expected archive region at index %u", curr_region->hrm_index());
 813       uint curr_index = curr_region->hrm_index();
 814       _archive_set.remove(curr_region);
 815       curr_region->set_free();
 816       curr_region->set_top(curr_region->bottom());
 817       if (curr_region != last_region) {
 818         curr_region = _hrm->next_region_in_heap(curr_region);
 819       } else {
 820         curr_region = NULL;
 821       }
 822       _hrm->shrink_at(curr_index, 1);
 823       uncommitted_regions++;
 824     }
 825 
 826     // Notify mark-sweep that this is no longer an archive range.
 827     G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
 828   }
 829 
 830   if (uncommitted_regions != 0) {
 831     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 832                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 833   }
 834   decrease_used(size_used);
 835 }
 836 
 837 oop G1CollectedHeap::materialize_archived_object(oop obj) {
 838   assert(obj != NULL, "archived obj is NULL");
 839   assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
 840 
 841   // Loading an archived object makes it strongly reachable. If it is
 842   // loaded during concurrent marking, it must be enqueued to the SATB
 843   // queue, shading the previously white object gray.
 844   G1BarrierSet::enqueue(obj);
 845 
 846   return obj;
 847 }
 848 
 849 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 850   ResourceMark rm; // For retrieving the thread names in log messages.
 851 
 852   // The structure of this method has a lot of similarities to
 853   // attempt_allocation_slow(). The reason these two were not merged
 854   // into a single one is that such a method would require several "if
 855   // allocation is not humongous do this, otherwise do that"
 856   // conditional paths which would obscure its flow. In fact, an early
 857   // version of this code did use a unified method which was harder to
 858   // follow and, as a result, it had subtle bugs that were hard to
 859   // track down. So keeping these two methods separate allows each to
 860   // be more readable. It will be good to keep these two in sync as
 861   // much as possible.
 862 
 863   assert_heap_not_locked_and_not_at_safepoint();
 864   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 865          "should only be called for humongous allocations");
 866 
 867   // Humongous objects can exhaust the heap quickly, so we should check if we
 868   // need to start a marking cycle at each humongous object allocation. We do
 869   // the check before we do the actual allocation. The reason for doing it
 870   // before the allocation is that we avoid having to keep track of the newly
 871   // allocated memory while we do a GC.
 872   if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
 873                                            word_size)) {
 874     collect(GCCause::_g1_humongous_allocation);
 875   }
 876 
 877   // We will loop until a) we manage to successfully perform the
 878   // allocation or b) we successfully schedule a collection which
 879   // fails to perform the allocation. b) is the only case when we'll
 880   // return NULL.
 881   HeapWord* result = NULL;
 882   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 883     bool should_try_gc;
 884     uint gc_count_before;
 885 
 886 
 887     {
 888       MutexLocker x(Heap_lock);
 889 
 890       // Given that humongous objects are not allocated in young
 891       // regions, we'll first try to do the allocation without doing a
 892       // collection hoping that there's enough space in the heap.
 893       result = humongous_obj_allocate(word_size);
 894       if (result != NULL) {
 895         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 896         policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 897         return result;
 898       }
 899 
 900       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 901       // the GCLocker initiated GC has been performed and then retry. This includes
 902       // the case when the GC Locker is not active but has not been performed.
 903       should_try_gc = !GCLocker::needs_gc();
 904       // Read the GC count while still holding the Heap_lock.
 905       gc_count_before = total_collections();
 906     }
 907 
 908     if (should_try_gc) {
 909       bool succeeded;
 910       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 911                                    GCCause::_g1_humongous_allocation);
 912       if (result != NULL) {
 913         assert(succeeded, "only way to get back a non-NULL result");
 914         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 915                              Thread::current()->name(), p2i(result));
 916         return result;
 917       }
 918 
 919       if (succeeded) {
 920         // We successfully scheduled a collection which failed to allocate. No
 921         // point in trying to allocate further. We'll just return NULL.
 922         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 923                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 924         return NULL;
 925       }
 926       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 927                            Thread::current()->name(), word_size);
 928     } else {
 929       // Failed to schedule a collection.
 930       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 931         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 932                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 933         return NULL;
 934       }
 935       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 936       // The GCLocker is either active or the GCLocker initiated
 937       // GC has not yet been performed. Stall until it is and
 938       // then retry the allocation.
 939       GCLocker::stall_until_clear();
 940       gclocker_retry_count += 1;
 941     }
 942 
 943 
 944     // We can reach here if we were unsuccessful in scheduling a
 945     // collection (because another thread beat us to it) or if we were
 946     // stalled due to the GC locker. In either can we should retry the
 947     // allocation attempt in case another thread successfully
 948     // performed a collection and reclaimed enough space.
 949     // Humongous object allocation always needs a lock, so we wait for the retry
 950     // in the next iteration of the loop, unlike for the regular iteration case.
 951     // Give a warning if we seem to be looping forever.
 952 
 953     if ((QueuedAllocationWarningCount > 0) &&
 954         (try_count % QueuedAllocationWarningCount == 0)) {
 955       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 956                              Thread::current()->name(), try_count, word_size);
 957     }
 958   }
 959 
 960   ShouldNotReachHere();
 961   return NULL;
 962 }
 963 
 964 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 965                                                            bool expect_null_mutator_alloc_region) {
 966   assert_at_safepoint_on_vm_thread();
 967   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 968          "the current alloc region was unexpectedly found to be non-NULL");
 969 
 970   if (!is_humongous(word_size)) {
 971     return _allocator->attempt_allocation_locked(word_size);
 972   } else {
 973     HeapWord* result = humongous_obj_allocate(word_size);
 974     if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
 975       collector_state()->set_initiate_conc_mark_if_possible(true);
 976     }
 977     return result;
 978   }
 979 
 980   ShouldNotReachHere();
 981 }
 982 
 983 class PostCompactionPrinterClosure: public HeapRegionClosure {
 984 private:
 985   G1HRPrinter* _hr_printer;
 986 public:
 987   bool do_heap_region(HeapRegion* hr) {
 988     assert(!hr->is_young(), "not expecting to find young regions");
 989     _hr_printer->post_compaction(hr);
 990     return false;
 991   }
 992 
 993   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 994     : _hr_printer(hr_printer) { }
 995 };
 996 
 997 void G1CollectedHeap::print_hrm_post_compaction() {
 998   if (_hr_printer.is_active()) {
 999     PostCompactionPrinterClosure cl(hr_printer());
1000     heap_region_iterate(&cl);
1001   }
1002 }
1003 
1004 void G1CollectedHeap::abort_concurrent_cycle() {
1005   // If we start the compaction before the CM threads finish
1006   // scanning the root regions we might trip them over as we'll
1007   // be moving objects / updating references. So let's wait until
1008   // they are done. By telling them to abort, they should complete
1009   // early.
1010   _cm->root_regions()->abort();
1011   _cm->root_regions()->wait_until_scan_finished();
1012 
1013   // Disable discovery and empty the discovered lists
1014   // for the CM ref processor.
1015   _ref_processor_cm->disable_discovery();
1016   _ref_processor_cm->abandon_partial_discovery();
1017   _ref_processor_cm->verify_no_references_recorded();
1018 
1019   // Abandon current iterations of concurrent marking and concurrent
1020   // refinement, if any are in progress.
1021   concurrent_mark()->concurrent_cycle_abort();
1022 }
1023 
1024 void G1CollectedHeap::prepare_heap_for_full_collection() {
1025   // Make sure we'll choose a new allocation region afterwards.
1026   _allocator->release_mutator_alloc_region();
1027   _allocator->abandon_gc_alloc_regions();
1028 
1029   // We may have added regions to the current incremental collection
1030   // set between the last GC or pause and now. We need to clear the
1031   // incremental collection set and then start rebuilding it afresh
1032   // after this full GC.
1033   abandon_collection_set(collection_set());
1034 
1035   tear_down_region_sets(false /* free_list_only */);
1036 
1037   hrm()->prepare_for_full_collection_start();
1038 }
1039 
1040 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1041   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1042   assert_used_and_recalculate_used_equal(this);
1043   _verifier->verify_region_sets_optional();
1044   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1045   _verifier->check_bitmaps("Full GC Start");
1046 }
1047 
1048 void G1CollectedHeap::prepare_heap_for_mutators() {
1049   hrm()->prepare_for_full_collection_end();
1050 
1051   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1052   ClassLoaderDataGraph::purge();
1053   MetaspaceUtils::verify_metrics();
1054 
1055   // Prepare heap for normal collections.
1056   assert(num_free_regions() == 0, "we should not have added any free regions");
1057   rebuild_region_sets(false /* free_list_only */);
1058   abort_refinement();
1059   resize_heap_if_necessary();
1060 
1061   // Rebuild the strong code root lists for each region
1062   rebuild_strong_code_roots();
1063 
1064   // Purge code root memory
1065   purge_code_root_memory();
1066 
1067   // Start a new incremental collection set for the next pause
1068   start_new_collection_set();
1069 
1070   _allocator->init_mutator_alloc_region();
1071 
1072   // Post collection state updates.
1073   MetaspaceGC::compute_new_size();
1074 }
1075 
1076 void G1CollectedHeap::abort_refinement() {
1077   if (_hot_card_cache->use_cache()) {
1078     _hot_card_cache->reset_hot_cache();
1079   }
1080 
1081   // Discard all remembered set updates.
1082   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1083   assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1084          "DCQS should be empty");
1085 }
1086 
1087 void G1CollectedHeap::verify_after_full_collection() {
1088   _hrm->verify_optional();
1089   _verifier->verify_region_sets_optional();
1090   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1091   // Clear the previous marking bitmap, if needed for bitmap verification.
1092   // Note we cannot do this when we clear the next marking bitmap in
1093   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1094   // objects marked during a full GC against the previous bitmap.
1095   // But we need to clear it before calling check_bitmaps below since
1096   // the full GC has compacted objects and updated TAMS but not updated
1097   // the prev bitmap.
1098   if (G1VerifyBitmaps) {
1099     GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1100     _cm->clear_prev_bitmap(workers());
1101   }
1102   // This call implicitly verifies that the next bitmap is clear after Full GC.
1103   _verifier->check_bitmaps("Full GC End");
1104 
1105   // At this point there should be no regions in the
1106   // entire heap tagged as young.
1107   assert(check_young_list_empty(), "young list should be empty at this point");
1108 
1109   // Note: since we've just done a full GC, concurrent
1110   // marking is no longer active. Therefore we need not
1111   // re-enable reference discovery for the CM ref processor.
1112   // That will be done at the start of the next marking cycle.
1113   // We also know that the STW processor should no longer
1114   // discover any new references.
1115   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1116   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1117   _ref_processor_stw->verify_no_references_recorded();
1118   _ref_processor_cm->verify_no_references_recorded();
1119 }
1120 
1121 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1122   // Post collection logging.
1123   // We should do this after we potentially resize the heap so
1124   // that all the COMMIT / UNCOMMIT events are generated before
1125   // the compaction events.
1126   print_hrm_post_compaction();
1127   heap_transition->print();
1128   print_heap_after_gc();
1129   print_heap_regions();
1130 #ifdef TRACESPINNING
1131   ParallelTaskTerminator::print_termination_counts();
1132 #endif
1133 }
1134 
1135 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1136                                          bool clear_all_soft_refs) {
1137   assert_at_safepoint_on_vm_thread();
1138 
1139   if (GCLocker::check_active_before_gc()) {
1140     // Full GC was not completed.
1141     return false;
1142   }
1143 
1144   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1145       soft_ref_policy()->should_clear_all_soft_refs();
1146 
1147   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1148   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1149 
1150   collector.prepare_collection();
1151   collector.collect();
1152   collector.complete_collection();
1153 
1154   // Full collection was successfully completed.
1155   return true;
1156 }
1157 
1158 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1159   // Currently, there is no facility in the do_full_collection(bool) API to notify
1160   // the caller that the collection did not succeed (e.g., because it was locked
1161   // out by the GC locker). So, right now, we'll ignore the return value.
1162   bool dummy = do_full_collection(true,                /* explicit_gc */
1163                                   clear_all_soft_refs);
1164 }
1165 
1166 void G1CollectedHeap::resize_heap_if_necessary() {
1167   assert_at_safepoint_on_vm_thread();
1168 
1169   // Capacity, free and used after the GC counted as full regions to
1170   // include the waste in the following calculations.
1171   const size_t capacity_after_gc = capacity();
1172   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1173 
1174   // This is enforced in arguments.cpp.
1175   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1176          "otherwise the code below doesn't make sense");
1177 
1178   // We don't have floating point command-line arguments
1179   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1180   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1181   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1182   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1183 
1184   // We have to be careful here as these two calculations can overflow
1185   // 32-bit size_t's.
1186   double used_after_gc_d = (double) used_after_gc;
1187   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1188   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1189 
1190   // Let's make sure that they are both under the max heap size, which
1191   // by default will make them fit into a size_t.
1192   double desired_capacity_upper_bound = (double) MaxHeapSize;
1193   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1194                                     desired_capacity_upper_bound);
1195   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1196                                     desired_capacity_upper_bound);
1197 
1198   // We can now safely turn them into size_t's.
1199   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1200   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1201 
1202   // This assert only makes sense here, before we adjust them
1203   // with respect to the min and max heap size.
1204   assert(minimum_desired_capacity <= maximum_desired_capacity,
1205          "minimum_desired_capacity = " SIZE_FORMAT ", "
1206          "maximum_desired_capacity = " SIZE_FORMAT,
1207          minimum_desired_capacity, maximum_desired_capacity);
1208 
1209   // Should not be greater than the heap max size. No need to adjust
1210   // it with respect to the heap min size as it's a lower bound (i.e.,
1211   // we'll try to make the capacity larger than it, not smaller).
1212   minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1213   // Should not be less than the heap min size. No need to adjust it
1214   // with respect to the heap max size as it's an upper bound (i.e.,
1215   // we'll try to make the capacity smaller than it, not greater).
1216   maximum_desired_capacity =  MAX2(maximum_desired_capacity, MinHeapSize);
1217 
1218   if (capacity_after_gc < minimum_desired_capacity) {
1219     // Don't expand unless it's significant
1220     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1221 
1222     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1223                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1224                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1225                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1226 
1227     expand(expand_bytes, _workers);
1228 
1229     // No expansion, now see if we want to shrink
1230   } else if (capacity_after_gc > maximum_desired_capacity) {
1231     // Capacity too large, compute shrinking size
1232     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1233 
1234     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1235                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1236                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1237                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1238 
1239     shrink(shrink_bytes);
1240   }
1241 }
1242 
1243 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1244                                                             bool do_gc,
1245                                                             bool clear_all_soft_refs,
1246                                                             bool expect_null_mutator_alloc_region,
1247                                                             bool* gc_succeeded) {
1248   *gc_succeeded = true;
1249   // Let's attempt the allocation first.
1250   HeapWord* result =
1251     attempt_allocation_at_safepoint(word_size,
1252                                     expect_null_mutator_alloc_region);
1253   if (result != NULL) {
1254     return result;
1255   }
1256 
1257   // In a G1 heap, we're supposed to keep allocation from failing by
1258   // incremental pauses.  Therefore, at least for now, we'll favor
1259   // expansion over collection.  (This might change in the future if we can
1260   // do something smarter than full collection to satisfy a failed alloc.)
1261   result = expand_and_allocate(word_size);
1262   if (result != NULL) {
1263     return result;
1264   }
1265 
1266   if (do_gc) {
1267     // Expansion didn't work, we'll try to do a Full GC.
1268     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1269                                        clear_all_soft_refs);
1270   }
1271 
1272   return NULL;
1273 }
1274 
1275 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1276                                                      bool* succeeded) {
1277   assert_at_safepoint_on_vm_thread();
1278 
1279   // Attempts to allocate followed by Full GC.
1280   HeapWord* result =
1281     satisfy_failed_allocation_helper(word_size,
1282                                      true,  /* do_gc */
1283                                      false, /* clear_all_soft_refs */
1284                                      false, /* expect_null_mutator_alloc_region */
1285                                      succeeded);
1286 
1287   if (result != NULL || !*succeeded) {
1288     return result;
1289   }
1290 
1291   // Attempts to allocate followed by Full GC that will collect all soft references.
1292   result = satisfy_failed_allocation_helper(word_size,
1293                                             true, /* do_gc */
1294                                             true, /* clear_all_soft_refs */
1295                                             true, /* expect_null_mutator_alloc_region */
1296                                             succeeded);
1297 
1298   if (result != NULL || !*succeeded) {
1299     return result;
1300   }
1301 
1302   // Attempts to allocate, no GC
1303   result = satisfy_failed_allocation_helper(word_size,
1304                                             false, /* do_gc */
1305                                             false, /* clear_all_soft_refs */
1306                                             true,  /* expect_null_mutator_alloc_region */
1307                                             succeeded);
1308 
1309   if (result != NULL) {
1310     return result;
1311   }
1312 
1313   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1314          "Flag should have been handled and cleared prior to this point");
1315 
1316   // What else?  We might try synchronous finalization later.  If the total
1317   // space available is large enough for the allocation, then a more
1318   // complete compaction phase than we've tried so far might be
1319   // appropriate.
1320   return NULL;
1321 }
1322 
1323 // Attempting to expand the heap sufficiently
1324 // to support an allocation of the given "word_size".  If
1325 // successful, perform the allocation and return the address of the
1326 // allocated block, or else "NULL".
1327 
1328 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1329   assert_at_safepoint_on_vm_thread();
1330 
1331   _verifier->verify_region_sets_optional();
1332 
1333   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1334   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1335                             word_size * HeapWordSize);
1336 
1337 
1338   if (expand(expand_bytes, _workers)) {
1339     _hrm->verify_optional();
1340     _verifier->verify_region_sets_optional();
1341     return attempt_allocation_at_safepoint(word_size,
1342                                            false /* expect_null_mutator_alloc_region */);
1343   }
1344   return NULL;
1345 }
1346 
1347 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1348   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1349   aligned_expand_bytes = align_up(aligned_expand_bytes,
1350                                        HeapRegion::GrainBytes);
1351 
1352   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1353                             expand_bytes, aligned_expand_bytes);
1354 
1355   if (is_maximal_no_gc()) {
1356     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1357     return false;
1358   }
1359 
1360   double expand_heap_start_time_sec = os::elapsedTime();
1361   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1362   assert(regions_to_expand > 0, "Must expand by at least one region");
1363 
1364   uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1365   if (expand_time_ms != NULL) {
1366     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1367   }
1368 
1369   if (expanded_by > 0) {
1370     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1371     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1372     policy()->record_new_heap_size(num_regions());
1373   } else {
1374     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1375 
1376     // The expansion of the virtual storage space was unsuccessful.
1377     // Let's see if it was because we ran out of swap.
1378     if (G1ExitOnExpansionFailure &&
1379         _hrm->available() >= regions_to_expand) {
1380       // We had head room...
1381       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1382     }
1383   }
1384   return regions_to_expand > 0;
1385 }
1386 
1387 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1388   size_t aligned_shrink_bytes =
1389     ReservedSpace::page_align_size_down(shrink_bytes);
1390   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1391                                          HeapRegion::GrainBytes);
1392   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1393 
1394   uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1395   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1396 
1397 
1398   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",
1399                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1400   if (num_regions_removed > 0) {
1401     policy()->record_new_heap_size(num_regions());
1402   } else {
1403     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1404   }
1405 }
1406 
1407 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1408   _verifier->verify_region_sets_optional();
1409 
1410   // We should only reach here at the end of a Full GC or during Remark which
1411   // means we should not not be holding to any GC alloc regions. The method
1412   // below will make sure of that and do any remaining clean up.
1413   _allocator->abandon_gc_alloc_regions();
1414 
1415   // Instead of tearing down / rebuilding the free lists here, we
1416   // could instead use the remove_all_pending() method on free_list to
1417   // remove only the ones that we need to remove.
1418   tear_down_region_sets(true /* free_list_only */);
1419   shrink_helper(shrink_bytes);
1420   rebuild_region_sets(true /* free_list_only */);
1421 
1422   _hrm->verify_optional();
1423   _verifier->verify_region_sets_optional();
1424 }
1425 
1426 class OldRegionSetChecker : public HeapRegionSetChecker {
1427 public:
1428   void check_mt_safety() {
1429     // Master Old Set MT safety protocol:
1430     // (a) If we're at a safepoint, operations on the master old set
1431     // should be invoked:
1432     // - by the VM thread (which will serialize them), or
1433     // - by the GC workers while holding the FreeList_lock, if we're
1434     //   at a safepoint for an evacuation pause (this lock is taken
1435     //   anyway when an GC alloc region is retired so that a new one
1436     //   is allocated from the free list), or
1437     // - by the GC workers while holding the OldSets_lock, if we're at a
1438     //   safepoint for a cleanup pause.
1439     // (b) If we're not at a safepoint, operations on the master old set
1440     // should be invoked while holding the Heap_lock.
1441 
1442     if (SafepointSynchronize::is_at_safepoint()) {
1443       guarantee(Thread::current()->is_VM_thread() ||
1444                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1445                 "master old set MT safety protocol at a safepoint");
1446     } else {
1447       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1448     }
1449   }
1450   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1451   const char* get_description() { return "Old Regions"; }
1452 };
1453 
1454 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1455 public:
1456   void check_mt_safety() {
1457     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1458               "May only change archive regions during initialization or safepoint.");
1459   }
1460   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1461   const char* get_description() { return "Archive Regions"; }
1462 };
1463 
1464 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1465 public:
1466   void check_mt_safety() {
1467     // Humongous Set MT safety protocol:
1468     // (a) If we're at a safepoint, operations on the master humongous
1469     // set should be invoked by either the VM thread (which will
1470     // serialize them) or by the GC workers while holding the
1471     // OldSets_lock.
1472     // (b) If we're not at a safepoint, operations on the master
1473     // humongous set should be invoked while holding the Heap_lock.
1474 
1475     if (SafepointSynchronize::is_at_safepoint()) {
1476       guarantee(Thread::current()->is_VM_thread() ||
1477                 OldSets_lock->owned_by_self(),
1478                 "master humongous set MT safety protocol at a safepoint");
1479     } else {
1480       guarantee(Heap_lock->owned_by_self(),
1481                 "master humongous set MT safety protocol outside a safepoint");
1482     }
1483   }
1484   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1485   const char* get_description() { return "Humongous Regions"; }
1486 };
1487 
1488 G1CollectedHeap::G1CollectedHeap() :
1489   CollectedHeap(),
1490   _young_gen_sampling_thread(NULL),
1491   _workers(NULL),
1492   _card_table(NULL),
1493   _soft_ref_policy(),
1494   _old_set("Old Region Set", new OldRegionSetChecker()),
1495   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1496   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1497   _bot(NULL),
1498   _listener(),
1499   _hrm(NULL),
1500   _allocator(NULL),
1501   _verifier(NULL),
1502   _summary_bytes_used(0),
1503   _archive_allocator(NULL),
1504   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1505   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1506   _expand_heap_after_alloc_failure(true),
1507   _g1mm(NULL),
1508   _humongous_reclaim_candidates(),
1509   _has_humongous_reclaim_candidates(false),
1510   _hr_printer(),
1511   _collector_state(),
1512   _old_marking_cycles_started(0),
1513   _old_marking_cycles_completed(0),
1514   _eden(),
1515   _survivor(),
1516   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1517   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1518   _policy(G1Policy::create_policy(_gc_timer_stw)),
1519   _heap_sizing_policy(NULL),
1520   _collection_set(this, _policy),
1521   _hot_card_cache(NULL),
1522   _rem_set(NULL),
1523   _cm(NULL),
1524   _cm_thread(NULL),
1525   _cr(NULL),
1526   _task_queues(NULL),
1527   _evacuation_failed(false),
1528   _evacuation_failed_info_array(NULL),
1529   _preserved_marks_set(true /* in_c_heap */),
1530 #ifndef PRODUCT
1531   _evacuation_failure_alot_for_current_gc(false),
1532   _evacuation_failure_alot_gc_number(0),
1533   _evacuation_failure_alot_count(0),
1534 #endif
1535   _ref_processor_stw(NULL),
1536   _is_alive_closure_stw(this),
1537   _is_subject_to_discovery_stw(this),
1538   _ref_processor_cm(NULL),
1539   _is_alive_closure_cm(this),
1540   _is_subject_to_discovery_cm(this),
1541   _region_attr() {
1542 
1543   _verifier = new G1HeapVerifier(this);
1544 
1545   _allocator = new G1Allocator(this);
1546 
1547   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1548 
1549   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1550 
1551   // Override the default _filler_array_max_size so that no humongous filler
1552   // objects are created.
1553   _filler_array_max_size = _humongous_object_threshold_in_words;
1554 
1555   uint n_queues = ParallelGCThreads;
1556   _task_queues = new RefToScanQueueSet(n_queues);
1557 
1558   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1559 
1560   for (uint i = 0; i < n_queues; i++) {
1561     RefToScanQueue* q = new RefToScanQueue();
1562     q->initialize();
1563     _task_queues->register_queue(i, q);
1564     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1565   }
1566 
1567   // Initialize the G1EvacuationFailureALot counters and flags.
1568   NOT_PRODUCT(reset_evacuation_should_fail();)
1569 
1570   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1571 }
1572 
1573 static size_t actual_reserved_page_size(ReservedSpace rs) {
1574   size_t page_size = os::vm_page_size();
1575   if (UseLargePages) {
1576     // There are two ways to manage large page memory.
1577     // 1. OS supports committing large page memory.
1578     // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1579     //    And ReservedSpace calls it 'special'. If we failed to set 'special',
1580     //    we reserved memory without large page.
1581     if (os::can_commit_large_page_memory() || rs.special()) {
1582       // An alignment at ReservedSpace comes from preferred page size or
1583       // heap alignment, and if the alignment came from heap alignment, it could be
1584       // larger than large pages size. So need to cap with the large page size.
1585       page_size = MIN2(rs.alignment(), os::large_page_size());
1586     }
1587   }
1588 
1589   return page_size;
1590 }
1591 
1592 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1593                                                                  size_t size,
1594                                                                  size_t translation_factor) {
1595   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1596   // Allocate a new reserved space, preferring to use large pages.
1597   ReservedSpace rs(size, preferred_page_size);
1598   size_t page_size = actual_reserved_page_size(rs);
1599   G1RegionToSpaceMapper* result  =
1600     G1RegionToSpaceMapper::create_mapper(rs,
1601                                          size,
1602                                          page_size,
1603                                          HeapRegion::GrainBytes,
1604                                          translation_factor,
1605                                          mtGC);
1606 
1607   os::trace_page_sizes_for_requested_size(description,
1608                                           size,
1609                                           preferred_page_size,
1610                                           page_size,
1611                                           rs.base(),
1612                                           rs.size());
1613 
1614   return result;
1615 }
1616 
1617 jint G1CollectedHeap::initialize_concurrent_refinement() {
1618   jint ecode = JNI_OK;
1619   _cr = G1ConcurrentRefine::create(&ecode);
1620   return ecode;
1621 }
1622 
1623 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1624   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1625   if (_young_gen_sampling_thread->osthread() == NULL) {
1626     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1627     return JNI_ENOMEM;
1628   }
1629   return JNI_OK;
1630 }
1631 
1632 jint G1CollectedHeap::initialize() {
1633   os::enable_vtime();
1634 
1635   // Necessary to satisfy locking discipline assertions.
1636 
1637   MutexLocker x(Heap_lock);
1638 
1639   // While there are no constraints in the GC code that HeapWordSize
1640   // be any particular value, there are multiple other areas in the
1641   // system which believe this to be true (e.g. oop->object_size in some
1642   // cases incorrectly returns the size in wordSize units rather than
1643   // HeapWordSize).
1644   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1645 
1646   size_t init_byte_size = InitialHeapSize;
1647   size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1648 
1649   // Ensure that the sizes are properly aligned.
1650   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1651   Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1652   Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1653 
1654   // Reserve the maximum.
1655 
1656   // When compressed oops are enabled, the preferred heap base
1657   // is calculated by subtracting the requested size from the
1658   // 32Gb boundary and using the result as the base address for
1659   // heap reservation. If the requested size is not aligned to
1660   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1661   // into the ReservedHeapSpace constructor) then the actual
1662   // base of the reserved heap may end up differing from the
1663   // address that was requested (i.e. the preferred heap base).
1664   // If this happens then we could end up using a non-optimal
1665   // compressed oops mode.
1666 
1667   ReservedSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1668                                                  HeapAlignment);
1669 
1670   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1671 
1672   // Create the barrier set for the entire reserved region.
1673   G1CardTable* ct = new G1CardTable(reserved_region());
1674   ct->initialize();
1675   G1BarrierSet* bs = new G1BarrierSet(ct);
1676   bs->initialize();
1677   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1678   BarrierSet::set_barrier_set(bs);
1679   _card_table = ct;
1680 
1681   G1BarrierSet::satb_mark_queue_set().initialize(this,
1682                                                  &bs->satb_mark_queue_buffer_allocator(),
1683                                                  G1SATBProcessCompletedThreshold,
1684                                                  G1SATBBufferEnqueueingThresholdPercent);
1685 
1686   // process_cards_threshold and max_cards are updated
1687   // later, based on the concurrent refinement object.
1688   G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1689                                                   &bs->dirty_card_queue_buffer_allocator(),
1690                                                   true); // init_free_ids
1691 
1692   // Create the hot card cache.
1693   _hot_card_cache = new G1HotCardCache(this);
1694 
1695   // Carve out the G1 part of the heap.
1696   ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1697   size_t page_size = actual_reserved_page_size(heap_rs);
1698   G1RegionToSpaceMapper* heap_storage =
1699     G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1700                                               g1_rs.size(),
1701                                               page_size,
1702                                               HeapRegion::GrainBytes,
1703                                               1,
1704                                               mtJavaHeap);
1705   if(heap_storage == NULL) {
1706     vm_shutdown_during_initialization("Could not initialize G1 heap");
1707     return JNI_ERR;
1708   }
1709 
1710   os::trace_page_sizes("Heap",
1711                        MinHeapSize,
1712                        reserved_byte_size,
1713                        page_size,
1714                        heap_rs.base(),
1715                        heap_rs.size());
1716   heap_storage->set_mapping_changed_listener(&_listener);
1717 
1718   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1719   G1RegionToSpaceMapper* bot_storage =
1720     create_aux_memory_mapper("Block Offset Table",
1721                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1722                              G1BlockOffsetTable::heap_map_factor());
1723 
1724   G1RegionToSpaceMapper* cardtable_storage =
1725     create_aux_memory_mapper("Card Table",
1726                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1727                              G1CardTable::heap_map_factor());
1728 
1729   G1RegionToSpaceMapper* card_counts_storage =
1730     create_aux_memory_mapper("Card Counts Table",
1731                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1732                              G1CardCounts::heap_map_factor());
1733 
1734   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1735   G1RegionToSpaceMapper* prev_bitmap_storage =
1736     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1737   G1RegionToSpaceMapper* next_bitmap_storage =
1738     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1739 
1740   _hrm = HeapRegionManager::create_manager(this);
1741 
1742   _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1743   _card_table->initialize(cardtable_storage);
1744   // Do later initialization work for concurrent refinement.
1745   _hot_card_cache->initialize(card_counts_storage);
1746 
1747   // 6843694 - ensure that the maximum region index can fit
1748   // in the remembered set structures.
1749   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1750   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1751 
1752   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1753   // start within the first card.
1754   guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1755   // Also create a G1 rem set.
1756   _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1757   _rem_set->initialize(max_reserved_capacity(), max_regions());
1758 
1759   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1760   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1761   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1762             "too many cards per region");
1763 
1764   FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1765 
1766   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1767 
1768   {
1769     HeapWord* start = _hrm->reserved().start();
1770     HeapWord* end = _hrm->reserved().end();
1771     size_t granularity = HeapRegion::GrainBytes;
1772 
1773     _region_attr.initialize(start, end, granularity);
1774     _humongous_reclaim_candidates.initialize(start, end, granularity);
1775   }
1776 
1777   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1778                           true /* are_GC_task_threads */,
1779                           false /* are_ConcurrentGC_threads */);
1780   if (_workers == NULL) {
1781     return JNI_ENOMEM;
1782   }
1783   _workers->initialize_workers();
1784 
1785   // Create the G1ConcurrentMark data structure and thread.
1786   // (Must do this late, so that "max_regions" is defined.)
1787   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1788   if (_cm == NULL || !_cm->completed_initialization()) {
1789     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1790     return JNI_ENOMEM;
1791   }
1792   _cm_thread = _cm->cm_thread();
1793 
1794   // Now expand into the initial heap size.
1795   if (!expand(init_byte_size, _workers)) {
1796     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1797     return JNI_ENOMEM;
1798   }
1799 
1800   // Perform any initialization actions delegated to the policy.
1801   policy()->init(this, &_collection_set);
1802 
1803   jint ecode = initialize_concurrent_refinement();
1804   if (ecode != JNI_OK) {
1805     return ecode;
1806   }
1807 
1808   ecode = initialize_young_gen_sampling_thread();
1809   if (ecode != JNI_OK) {
1810     return ecode;
1811   }
1812 
1813   {
1814     G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1815     dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1816     dcqs.set_max_cards(concurrent_refine()->red_zone());
1817   }
1818 
1819   // Here we allocate the dummy HeapRegion that is required by the
1820   // G1AllocRegion class.
1821   HeapRegion* dummy_region = _hrm->get_dummy_region();
1822 
1823   // We'll re-use the same region whether the alloc region will
1824   // require BOT updates or not and, if it doesn't, then a non-young
1825   // region will complain that it cannot support allocations without
1826   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1827   dummy_region->set_eden();
1828   // Make sure it's full.
1829   dummy_region->set_top(dummy_region->end());
1830   G1AllocRegion::setup(this, dummy_region);
1831 
1832   _allocator->init_mutator_alloc_region();
1833 
1834   // Do create of the monitoring and management support so that
1835   // values in the heap have been properly initialized.
1836   _g1mm = new G1MonitoringSupport(this);
1837 
1838   G1StringDedup::initialize();
1839 
1840   _preserved_marks_set.init(ParallelGCThreads);
1841 
1842   _collection_set.initialize(max_regions());
1843 
1844   return JNI_OK;
1845 }
1846 
1847 void G1CollectedHeap::stop() {
1848   // Stop all concurrent threads. We do this to make sure these threads
1849   // do not continue to execute and access resources (e.g. logging)
1850   // that are destroyed during shutdown.
1851   _cr->stop();
1852   _young_gen_sampling_thread->stop();
1853   _cm_thread->stop();
1854   if (G1StringDedup::is_enabled()) {
1855     G1StringDedup::stop();
1856   }
1857 }
1858 
1859 void G1CollectedHeap::safepoint_synchronize_begin() {
1860   SuspendibleThreadSet::synchronize();
1861 }
1862 
1863 void G1CollectedHeap::safepoint_synchronize_end() {
1864   SuspendibleThreadSet::desynchronize();
1865 }
1866 
1867 void G1CollectedHeap::post_initialize() {
1868   CollectedHeap::post_initialize();
1869   ref_processing_init();
1870 }
1871 
1872 void G1CollectedHeap::ref_processing_init() {
1873   // Reference processing in G1 currently works as follows:
1874   //
1875   // * There are two reference processor instances. One is
1876   //   used to record and process discovered references
1877   //   during concurrent marking; the other is used to
1878   //   record and process references during STW pauses
1879   //   (both full and incremental).
1880   // * Both ref processors need to 'span' the entire heap as
1881   //   the regions in the collection set may be dotted around.
1882   //
1883   // * For the concurrent marking ref processor:
1884   //   * Reference discovery is enabled at initial marking.
1885   //   * Reference discovery is disabled and the discovered
1886   //     references processed etc during remarking.
1887   //   * Reference discovery is MT (see below).
1888   //   * Reference discovery requires a barrier (see below).
1889   //   * Reference processing may or may not be MT
1890   //     (depending on the value of ParallelRefProcEnabled
1891   //     and ParallelGCThreads).
1892   //   * A full GC disables reference discovery by the CM
1893   //     ref processor and abandons any entries on it's
1894   //     discovered lists.
1895   //
1896   // * For the STW processor:
1897   //   * Non MT discovery is enabled at the start of a full GC.
1898   //   * Processing and enqueueing during a full GC is non-MT.
1899   //   * During a full GC, references are processed after marking.
1900   //
1901   //   * Discovery (may or may not be MT) is enabled at the start
1902   //     of an incremental evacuation pause.
1903   //   * References are processed near the end of a STW evacuation pause.
1904   //   * For both types of GC:
1905   //     * Discovery is atomic - i.e. not concurrent.
1906   //     * Reference discovery will not need a barrier.
1907 
1908   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1909 
1910   // Concurrent Mark ref processor
1911   _ref_processor_cm =
1912     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1913                            mt_processing,                                  // mt processing
1914                            ParallelGCThreads,                              // degree of mt processing
1915                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1916                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1917                            false,                                          // Reference discovery is not atomic
1918                            &_is_alive_closure_cm,                          // is alive closure
1919                            true);                                          // allow changes to number of processing threads
1920 
1921   // STW ref processor
1922   _ref_processor_stw =
1923     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1924                            mt_processing,                        // mt processing
1925                            ParallelGCThreads,                    // degree of mt processing
1926                            (ParallelGCThreads > 1),              // mt discovery
1927                            ParallelGCThreads,                    // degree of mt discovery
1928                            true,                                 // Reference discovery is atomic
1929                            &_is_alive_closure_stw,               // is alive closure
1930                            true);                                // allow changes to number of processing threads
1931 }
1932 
1933 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1934   return &_soft_ref_policy;
1935 }
1936 
1937 size_t G1CollectedHeap::capacity() const {
1938   return _hrm->length() * HeapRegion::GrainBytes;
1939 }
1940 
1941 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1942   return _hrm->total_free_bytes();
1943 }
1944 
1945 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1946   _hot_card_cache->drain(cl, worker_i);
1947 }
1948 
1949 void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1950   G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1951   size_t n_completed_buffers = 0;
1952   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1953     n_completed_buffers++;
1954   }
1955   assert(dcqs.num_cards() == 0, "Completed buffers exist!");
1956   phase_times()->record_thread_work_item(G1GCPhaseTimes::MergeLB, worker_i, n_completed_buffers, G1GCPhaseTimes::MergeLBProcessedBuffers);
1957 }
1958 
1959 // Computes the sum of the storage used by the various regions.
1960 size_t G1CollectedHeap::used() const {
1961   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1962   if (_archive_allocator != NULL) {
1963     result += _archive_allocator->used();
1964   }
1965   return result;
1966 }
1967 
1968 size_t G1CollectedHeap::used_unlocked() const {
1969   return _summary_bytes_used;
1970 }
1971 
1972 class SumUsedClosure: public HeapRegionClosure {
1973   size_t _used;
1974 public:
1975   SumUsedClosure() : _used(0) {}
1976   bool do_heap_region(HeapRegion* r) {
1977     _used += r->used();
1978     return false;
1979   }
1980   size_t result() { return _used; }
1981 };
1982 
1983 size_t G1CollectedHeap::recalculate_used() const {
1984   SumUsedClosure blk;
1985   heap_region_iterate(&blk);
1986   return blk.result();
1987 }
1988 
1989 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1990   switch (cause) {
1991     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1992     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1993     case GCCause::_wb_conc_mark:                        return true;
1994     default :                                           return false;
1995   }
1996 }
1997 
1998 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1999   switch (cause) {
2000     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2001     case GCCause::_g1_humongous_allocation: return true;
2002     case GCCause::_g1_periodic_collection:  return G1PeriodicGCInvokesConcurrent;
2003     default:                                return is_user_requested_concurrent_full_gc(cause);
2004   }
2005 }
2006 
2007 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2008   if(policy()->force_upgrade_to_full()) {
2009     return true;
2010   } else if (should_do_concurrent_full_gc(_gc_cause)) {
2011     return false;
2012   } else if (has_regions_left_for_allocation()) {
2013     return false;
2014   } else {
2015     return true;
2016   }
2017 }
2018 
2019 #ifndef PRODUCT
2020 void G1CollectedHeap::allocate_dummy_regions() {
2021   // Let's fill up most of the region
2022   size_t word_size = HeapRegion::GrainWords - 1024;
2023   // And as a result the region we'll allocate will be humongous.
2024   guarantee(is_humongous(word_size), "sanity");
2025 
2026   // _filler_array_max_size is set to humongous object threshold
2027   // but temporarily change it to use CollectedHeap::fill_with_object().
2028   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2029 
2030   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2031     // Let's use the existing mechanism for the allocation
2032     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2033     if (dummy_obj != NULL) {
2034       MemRegion mr(dummy_obj, word_size);
2035       CollectedHeap::fill_with_object(mr);
2036     } else {
2037       // If we can't allocate once, we probably cannot allocate
2038       // again. Let's get out of the loop.
2039       break;
2040     }
2041   }
2042 }
2043 #endif // !PRODUCT
2044 
2045 void G1CollectedHeap::increment_old_marking_cycles_started() {
2046   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2047          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2048          "Wrong marking cycle count (started: %d, completed: %d)",
2049          _old_marking_cycles_started, _old_marking_cycles_completed);
2050 
2051   _old_marking_cycles_started++;
2052 }
2053 
2054 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2055   MonitorLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2056 
2057   // We assume that if concurrent == true, then the caller is a
2058   // concurrent thread that was joined the Suspendible Thread
2059   // Set. If there's ever a cheap way to check this, we should add an
2060   // assert here.
2061 
2062   // Given that this method is called at the end of a Full GC or of a
2063   // concurrent cycle, and those can be nested (i.e., a Full GC can
2064   // interrupt a concurrent cycle), the number of full collections
2065   // completed should be either one (in the case where there was no
2066   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2067   // behind the number of full collections started.
2068 
2069   // This is the case for the inner caller, i.e. a Full GC.
2070   assert(concurrent ||
2071          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2072          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2073          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2074          "is inconsistent with _old_marking_cycles_completed = %u",
2075          _old_marking_cycles_started, _old_marking_cycles_completed);
2076 
2077   // This is the case for the outer caller, i.e. the concurrent cycle.
2078   assert(!concurrent ||
2079          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2080          "for outer caller (concurrent cycle): "
2081          "_old_marking_cycles_started = %u "
2082          "is inconsistent with _old_marking_cycles_completed = %u",
2083          _old_marking_cycles_started, _old_marking_cycles_completed);
2084 
2085   _old_marking_cycles_completed += 1;
2086 
2087   // We need to clear the "in_progress" flag in the CM thread before
2088   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2089   // is set) so that if a waiter requests another System.gc() it doesn't
2090   // incorrectly see that a marking cycle is still in progress.
2091   if (concurrent) {
2092     _cm_thread->set_idle();
2093   }
2094 
2095   // This notify_all() will ensure that a thread that called
2096   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2097   // and it's waiting for a full GC to finish will be woken up. It is
2098   // waiting in VM_G1CollectForAllocation::doit_epilogue().
2099   FullGCCount_lock->notify_all();
2100 }
2101 
2102 void G1CollectedHeap::collect(GCCause::Cause cause) {
2103   try_collect(cause, true);
2104 }
2105 
2106 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) {
2107   assert_heap_not_locked();
2108 
2109   bool gc_succeeded;
2110   bool should_retry_gc;
2111 
2112   do {
2113     should_retry_gc = false;
2114 
2115     uint gc_count_before;
2116     uint old_marking_count_before;
2117     uint full_gc_count_before;
2118 
2119     {
2120       MutexLocker ml(Heap_lock);
2121 
2122       // Read the GC count while holding the Heap_lock
2123       gc_count_before = total_collections();
2124       full_gc_count_before = total_full_collections();
2125       old_marking_count_before = _old_marking_cycles_started;
2126     }
2127 
2128     if (should_do_concurrent_full_gc(cause)) {
2129       // Schedule an initial-mark evacuation pause that will start a
2130       // concurrent cycle. We're setting word_size to 0 which means that
2131       // we are not requesting a post-GC allocation.
2132       VM_G1CollectForAllocation op(0,     /* word_size */
2133                                    gc_count_before,
2134                                    cause,
2135                                    true,  /* should_initiate_conc_mark */
2136                                    policy()->max_pause_time_ms());
2137       VMThread::execute(&op);
2138       gc_succeeded = op.gc_succeeded();
2139       if (!gc_succeeded && retry_on_gc_failure) {
2140         if (old_marking_count_before == _old_marking_cycles_started) {
2141           should_retry_gc = op.should_retry_gc();
2142         } else {
2143           // A Full GC happened while we were trying to schedule the
2144           // concurrent cycle. No point in starting a new cycle given
2145           // that the whole heap was collected anyway.
2146         }
2147 
2148         if (should_retry_gc && GCLocker::is_active_and_needs_gc()) {
2149           GCLocker::stall_until_clear();
2150         }
2151       }
2152     } else if (GCLocker::should_discard(cause, gc_count_before)) {
2153       // Return false to be consistent with VMOp failure due to
2154       // another collection slipping in after our gc_count but before
2155       // our request is processed.  _gc_locker collections upgraded by
2156       // GCLockerInvokesConcurrent are handled above and never discarded.
2157       return false;
2158     } else {
2159       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2160           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2161 
2162         // Schedule a standard evacuation pause. We're setting word_size
2163         // to 0 which means that we are not requesting a post-GC allocation.
2164         VM_G1CollectForAllocation op(0,     /* word_size */
2165                                      gc_count_before,
2166                                      cause,
2167                                      false, /* should_initiate_conc_mark */
2168                                      policy()->max_pause_time_ms());
2169         VMThread::execute(&op);
2170         gc_succeeded = op.gc_succeeded();
2171       } else {
2172         // Schedule a Full GC.
2173         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2174         VMThread::execute(&op);
2175         gc_succeeded = op.gc_succeeded();
2176       }
2177     }
2178   } while (should_retry_gc);
2179   return gc_succeeded;
2180 }
2181 
2182 bool G1CollectedHeap::is_in(const void* p) const {
2183   if (_hrm->reserved().contains(p)) {
2184     // Given that we know that p is in the reserved space,
2185     // heap_region_containing() should successfully
2186     // return the containing region.
2187     HeapRegion* hr = heap_region_containing(p);
2188     return hr->is_in(p);
2189   } else {
2190     return false;
2191   }
2192 }
2193 
2194 #ifdef ASSERT
2195 bool G1CollectedHeap::is_in_exact(const void* p) const {
2196   bool contains = reserved_region().contains(p);
2197   bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2198   if (contains && available) {
2199     return true;
2200   } else {
2201     return false;
2202   }
2203 }
2204 #endif
2205 
2206 // Iteration functions.
2207 
2208 // Iterates an ObjectClosure over all objects within a HeapRegion.
2209 
2210 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2211   ObjectClosure* _cl;
2212 public:
2213   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2214   bool do_heap_region(HeapRegion* r) {
2215     if (!r->is_continues_humongous()) {
2216       r->object_iterate(_cl);
2217     }
2218     return false;
2219   }
2220 };
2221 
2222 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2223   IterateObjectClosureRegionClosure blk(cl);
2224   heap_region_iterate(&blk);
2225 }
2226 
2227 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2228   _hrm->iterate(cl);
2229 }
2230 
2231 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2232                                                                  HeapRegionClaimer *hrclaimer,
2233                                                                  uint worker_id) const {
2234   _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2235 }
2236 
2237 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2238                                                          HeapRegionClaimer *hrclaimer) const {
2239   _hrm->par_iterate(cl, hrclaimer, 0);
2240 }
2241 
2242 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2243   _collection_set.iterate(cl);
2244 }
2245 
2246 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2247   _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2248 }
2249 
2250 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2251   HeapRegion* hr = heap_region_containing(addr);
2252   return hr->block_start(addr);
2253 }
2254 
2255 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2256   HeapRegion* hr = heap_region_containing(addr);
2257   return hr->block_is_obj(addr);
2258 }
2259 
2260 bool G1CollectedHeap::supports_tlab_allocation() const {
2261   return true;
2262 }
2263 
2264 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2265   return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2266 }
2267 
2268 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2269   return _eden.length() * HeapRegion::GrainBytes;
2270 }
2271 
2272 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2273 // must be equal to the humongous object limit.
2274 size_t G1CollectedHeap::max_tlab_size() const {
2275   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2276 }
2277 
2278 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2279   return _allocator->unsafe_max_tlab_alloc();
2280 }
2281 
2282 size_t G1CollectedHeap::max_capacity() const {
2283   return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2284 }
2285 
2286 size_t G1CollectedHeap::max_reserved_capacity() const {
2287   return _hrm->max_length() * HeapRegion::GrainBytes;
2288 }
2289 
2290 jlong G1CollectedHeap::millis_since_last_gc() {
2291   // See the notes in GenCollectedHeap::millis_since_last_gc()
2292   // for more information about the implementation.
2293   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2294                   _policy->collection_pause_end_millis();
2295   if (ret_val < 0) {
2296     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2297       ". returning zero instead.", ret_val);
2298     return 0;
2299   }
2300   return ret_val;
2301 }
2302 
2303 void G1CollectedHeap::deduplicate_string(oop str) {
2304   assert(java_lang_String::is_instance(str), "invariant");
2305 
2306   if (G1StringDedup::is_enabled()) {
2307     G1StringDedup::deduplicate(str);
2308   }
2309 }
2310 
2311 void G1CollectedHeap::prepare_for_verify() {
2312   _verifier->prepare_for_verify();
2313 }
2314 
2315 void G1CollectedHeap::verify(VerifyOption vo) {
2316   _verifier->verify(vo);
2317 }
2318 
2319 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2320   return true;
2321 }
2322 
2323 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2324   return _cm_thread->request_concurrent_phase(phase);
2325 }
2326 
2327 bool G1CollectedHeap::is_heterogeneous_heap() const {
2328   return G1Arguments::is_heterogeneous_heap();
2329 }
2330 
2331 class PrintRegionClosure: public HeapRegionClosure {
2332   outputStream* _st;
2333 public:
2334   PrintRegionClosure(outputStream* st) : _st(st) {}
2335   bool do_heap_region(HeapRegion* r) {
2336     r->print_on(_st);
2337     return false;
2338   }
2339 };
2340 
2341 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2342                                        const HeapRegion* hr,
2343                                        const VerifyOption vo) const {
2344   switch (vo) {
2345   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2346   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2347   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2348   default:                            ShouldNotReachHere();
2349   }
2350   return false; // keep some compilers happy
2351 }
2352 
2353 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2354                                        const VerifyOption vo) const {
2355   switch (vo) {
2356   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2357   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2358   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2359   default:                            ShouldNotReachHere();
2360   }
2361   return false; // keep some compilers happy
2362 }
2363 
2364 void G1CollectedHeap::print_heap_regions() const {
2365   LogTarget(Trace, gc, heap, region) lt;
2366   if (lt.is_enabled()) {
2367     LogStream ls(lt);
2368     print_regions_on(&ls);
2369   }
2370 }
2371 
2372 void G1CollectedHeap::print_on(outputStream* st) const {
2373   st->print(" %-20s", "garbage-first heap");
2374   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2375             capacity()/K, used_unlocked()/K);
2376   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2377             p2i(_hrm->reserved().start()),
2378             p2i(_hrm->reserved().end()));
2379   st->cr();
2380   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2381   uint young_regions = young_regions_count();
2382   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2383             (size_t) young_regions * HeapRegion::GrainBytes / K);
2384   uint survivor_regions = survivor_regions_count();
2385   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2386             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2387   st->cr();
2388   MetaspaceUtils::print_on(st);
2389 }
2390 
2391 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2392   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2393                "HS=humongous(starts), HC=humongous(continues), "
2394                "CS=collection set, F=free, A=archive, "
2395                "TAMS=top-at-mark-start (previous, next)");
2396   PrintRegionClosure blk(st);
2397   heap_region_iterate(&blk);
2398 }
2399 
2400 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2401   print_on(st);
2402 
2403   // Print the per-region information.
2404   print_regions_on(st);
2405 }
2406 
2407 void G1CollectedHeap::print_on_error(outputStream* st) const {
2408   this->CollectedHeap::print_on_error(st);
2409 
2410   if (_cm != NULL) {
2411     st->cr();
2412     _cm->print_on_error(st);
2413   }
2414 }
2415 
2416 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2417   workers()->print_worker_threads_on(st);
2418   _cm_thread->print_on(st);
2419   st->cr();
2420   _cm->print_worker_threads_on(st);
2421   _cr->print_threads_on(st);
2422   _young_gen_sampling_thread->print_on(st);
2423   if (G1StringDedup::is_enabled()) {
2424     G1StringDedup::print_worker_threads_on(st);
2425   }
2426 }
2427 
2428 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2429   workers()->threads_do(tc);
2430   tc->do_thread(_cm_thread);
2431   _cm->threads_do(tc);
2432   _cr->threads_do(tc);
2433   tc->do_thread(_young_gen_sampling_thread);
2434   if (G1StringDedup::is_enabled()) {
2435     G1StringDedup::threads_do(tc);
2436   }
2437 }
2438 
2439 void G1CollectedHeap::print_tracing_info() const {
2440   rem_set()->print_summary_info();
2441   concurrent_mark()->print_summary_info();
2442 }
2443 
2444 #ifndef PRODUCT
2445 // Helpful for debugging RSet issues.
2446 
2447 class PrintRSetsClosure : public HeapRegionClosure {
2448 private:
2449   const char* _msg;
2450   size_t _occupied_sum;
2451 
2452 public:
2453   bool do_heap_region(HeapRegion* r) {
2454     HeapRegionRemSet* hrrs = r->rem_set();
2455     size_t occupied = hrrs->occupied();
2456     _occupied_sum += occupied;
2457 
2458     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2459     if (occupied == 0) {
2460       tty->print_cr("  RSet is empty");
2461     } else {
2462       hrrs->print();
2463     }
2464     tty->print_cr("----------");
2465     return false;
2466   }
2467 
2468   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2469     tty->cr();
2470     tty->print_cr("========================================");
2471     tty->print_cr("%s", msg);
2472     tty->cr();
2473   }
2474 
2475   ~PrintRSetsClosure() {
2476     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2477     tty->print_cr("========================================");
2478     tty->cr();
2479   }
2480 };
2481 
2482 void G1CollectedHeap::print_cset_rsets() {
2483   PrintRSetsClosure cl("Printing CSet RSets");
2484   collection_set_iterate_all(&cl);
2485 }
2486 
2487 void G1CollectedHeap::print_all_rsets() {
2488   PrintRSetsClosure cl("Printing All RSets");;
2489   heap_region_iterate(&cl);
2490 }
2491 #endif // PRODUCT
2492 
2493 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2494 
2495   size_t eden_used_bytes = _eden.used_bytes();
2496   size_t survivor_used_bytes = _survivor.used_bytes();
2497   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2498 
2499   size_t eden_capacity_bytes =
2500     (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2501 
2502   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2503   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2504                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2505 }
2506 
2507 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2508   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2509                        stats->unused(), stats->used(), stats->region_end_waste(),
2510                        stats->regions_filled(), stats->direct_allocated(),
2511                        stats->failure_used(), stats->failure_waste());
2512 }
2513 
2514 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2515   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2516   gc_tracer->report_gc_heap_summary(when, heap_summary);
2517 
2518   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2519   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2520 }
2521 
2522 G1CollectedHeap* G1CollectedHeap::heap() {
2523   CollectedHeap* heap = Universe::heap();
2524   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2525   assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2526   return (G1CollectedHeap*)heap;
2527 }
2528 
2529 void G1CollectedHeap::gc_prologue(bool full) {
2530   // always_do_update_barrier = false;
2531   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2532 
2533   // This summary needs to be printed before incrementing total collections.
2534   rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2535 
2536   // Update common counters.
2537   increment_total_collections(full /* full gc */);
2538   if (full || collector_state()->in_initial_mark_gc()) {
2539     increment_old_marking_cycles_started();
2540   }
2541 
2542   // Fill TLAB's and such
2543   double start = os::elapsedTime();
2544   ensure_parsability(true);
2545   phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2546 }
2547 
2548 void G1CollectedHeap::gc_epilogue(bool full) {
2549   // Update common counters.
2550   if (full) {
2551     // Update the number of full collections that have been completed.
2552     increment_old_marking_cycles_completed(false /* concurrent */);
2553   }
2554 
2555   // We are at the end of the GC. Total collections has already been increased.
2556   rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2557 
2558   // FIXME: what is this about?
2559   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2560   // is set.
2561 #if COMPILER2_OR_JVMCI
2562   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2563 #endif
2564   // always_do_update_barrier = true;
2565 
2566   double start = os::elapsedTime();
2567   resize_all_tlabs();
2568   phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2569 
2570   MemoryService::track_memory_usage();
2571   // We have just completed a GC. Update the soft reference
2572   // policy with the new heap occupancy
2573   Universe::update_heap_info_at_gc();
2574 }
2575 
2576 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2577                                                uint gc_count_before,
2578                                                bool* succeeded,
2579                                                GCCause::Cause gc_cause) {
2580   assert_heap_not_locked_and_not_at_safepoint();
2581   VM_G1CollectForAllocation op(word_size,
2582                                gc_count_before,
2583                                gc_cause,
2584                                false, /* should_initiate_conc_mark */
2585                                policy()->max_pause_time_ms());
2586   VMThread::execute(&op);
2587 
2588   HeapWord* result = op.result();
2589   bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2590   assert(result == NULL || ret_succeeded,
2591          "the result should be NULL if the VM did not succeed");
2592   *succeeded = ret_succeeded;
2593 
2594   assert_heap_not_locked();
2595   return result;
2596 }
2597 
2598 void G1CollectedHeap::do_concurrent_mark() {
2599   MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2600   if (!_cm_thread->in_progress()) {
2601     _cm_thread->set_started();
2602     CGC_lock->notify();
2603   }
2604 }
2605 
2606 size_t G1CollectedHeap::pending_card_num() {
2607   struct CountCardsClosure : public ThreadClosure {
2608     size_t _cards;
2609     CountCardsClosure() : _cards(0) {}
2610     virtual void do_thread(Thread* t) {
2611       _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2612     }
2613   } count_from_threads;
2614   Threads::threads_do(&count_from_threads);
2615 
2616   G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2617   dcqs.verify_num_cards();
2618 
2619   return dcqs.num_cards() + count_from_threads._cards;
2620 }
2621 
2622 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2623   // We don't nominate objects with many remembered set entries, on
2624   // the assumption that such objects are likely still live.
2625   HeapRegionRemSet* rem_set = r->rem_set();
2626 
2627   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2628          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2629          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2630 }
2631 
2632 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure {
2633  private:
2634   size_t _total_humongous;
2635   size_t _candidate_humongous;
2636 
2637   bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2638     assert(region->is_starts_humongous(), "Must start a humongous object");
2639 
2640     oop obj = oop(region->bottom());
2641 
2642     // Dead objects cannot be eager reclaim candidates. Due to class
2643     // unloading it is unsafe to query their classes so we return early.
2644     if (g1h->is_obj_dead(obj, region)) {
2645       return false;
2646     }
2647 
2648     // If we do not have a complete remembered set for the region, then we can
2649     // not be sure that we have all references to it.
2650     if (!region->rem_set()->is_complete()) {
2651       return false;
2652     }
2653     // Candidate selection must satisfy the following constraints
2654     // while concurrent marking is in progress:
2655     //
2656     // * In order to maintain SATB invariants, an object must not be
2657     // reclaimed if it was allocated before the start of marking and
2658     // has not had its references scanned.  Such an object must have
2659     // its references (including type metadata) scanned to ensure no
2660     // live objects are missed by the marking process.  Objects
2661     // allocated after the start of concurrent marking don't need to
2662     // be scanned.
2663     //
2664     // * An object must not be reclaimed if it is on the concurrent
2665     // mark stack.  Objects allocated after the start of concurrent
2666     // marking are never pushed on the mark stack.
2667     //
2668     // Nominating only objects allocated after the start of concurrent
2669     // marking is sufficient to meet both constraints.  This may miss
2670     // some objects that satisfy the constraints, but the marking data
2671     // structures don't support efficiently performing the needed
2672     // additional tests or scrubbing of the mark stack.
2673     //
2674     // However, we presently only nominate is_typeArray() objects.
2675     // A humongous object containing references induces remembered
2676     // set entries on other regions.  In order to reclaim such an
2677     // object, those remembered sets would need to be cleaned up.
2678     //
2679     // We also treat is_typeArray() objects specially, allowing them
2680     // to be reclaimed even if allocated before the start of
2681     // concurrent mark.  For this we rely on mark stack insertion to
2682     // exclude is_typeArray() objects, preventing reclaiming an object
2683     // that is in the mark stack.  We also rely on the metadata for
2684     // such objects to be built-in and so ensured to be kept live.
2685     // Frequent allocation and drop of large binary blobs is an
2686     // important use case for eager reclaim, and this special handling
2687     // may reduce needed headroom.
2688 
2689     return obj->is_typeArray() &&
2690            g1h->is_potential_eager_reclaim_candidate(region);
2691   }
2692 
2693  public:
2694   RegisterRegionsWithRegionAttrTableClosure()
2695   : _total_humongous(0),
2696     _candidate_humongous(0) {
2697   }
2698 
2699   virtual bool do_heap_region(HeapRegion* r) {
2700     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2701 
2702     if (!r->is_starts_humongous()) {
2703       g1h->register_region_with_region_attr(r);
2704       return false;
2705     }
2706 
2707     bool is_candidate = humongous_region_is_candidate(g1h, r);
2708     uint rindex = r->hrm_index();
2709     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2710     if (is_candidate) {
2711       g1h->register_humongous_region_with_region_attr(rindex);
2712       _candidate_humongous++;
2713       // We will later handle the remembered sets of these regions.
2714     } else {
2715       g1h->register_region_with_region_attr(r);
2716     }
2717     _total_humongous++;
2718 
2719     return false;
2720   }
2721 
2722   size_t total_humongous() const { return _total_humongous; }
2723   size_t candidate_humongous() const { return _candidate_humongous; }
2724 };
2725 
2726 void G1CollectedHeap::register_regions_with_region_attr() {
2727   Ticks start = Ticks::now();
2728 
2729   RegisterRegionsWithRegionAttrTableClosure cl;
2730   heap_region_iterate(&cl);
2731 
2732   phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0,
2733                                          cl.total_humongous(),
2734                                          cl.candidate_humongous());
2735   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2736 }
2737 
2738 #ifndef PRODUCT
2739 void G1CollectedHeap::verify_region_attr_remset_update() {
2740   class VerifyRegionAttrRemSet : public HeapRegionClosure {
2741   public:
2742     virtual bool do_heap_region(HeapRegion* r) {
2743       G1CollectedHeap* g1h = G1CollectedHeap::heap();
2744       bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2745       assert(r->rem_set()->is_tracked() == needs_remset_update,
2746              "Region %u remset tracking status (%s) different to region attribute (%s)",
2747              r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2748       return false;
2749     }
2750   } cl;
2751   heap_region_iterate(&cl);
2752 }
2753 #endif
2754 
2755 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2756   public:
2757     bool do_heap_region(HeapRegion* hr) {
2758       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2759         hr->verify_rem_set();
2760       }
2761       return false;
2762     }
2763 };
2764 
2765 uint G1CollectedHeap::num_task_queues() const {
2766   return _task_queues->size();
2767 }
2768 
2769 #if TASKQUEUE_STATS
2770 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2771   st->print_raw_cr("GC Task Stats");
2772   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2773   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2774 }
2775 
2776 void G1CollectedHeap::print_taskqueue_stats() const {
2777   if (!log_is_enabled(Trace, gc, task, stats)) {
2778     return;
2779   }
2780   Log(gc, task, stats) log;
2781   ResourceMark rm;
2782   LogStream ls(log.trace());
2783   outputStream* st = &ls;
2784 
2785   print_taskqueue_stats_hdr(st);
2786 
2787   TaskQueueStats totals;
2788   const uint n = num_task_queues();
2789   for (uint i = 0; i < n; ++i) {
2790     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2791     totals += task_queue(i)->stats;
2792   }
2793   st->print_raw("tot "); totals.print(st); st->cr();
2794 
2795   DEBUG_ONLY(totals.verify());
2796 }
2797 
2798 void G1CollectedHeap::reset_taskqueue_stats() {
2799   const uint n = num_task_queues();
2800   for (uint i = 0; i < n; ++i) {
2801     task_queue(i)->stats.reset();
2802   }
2803 }
2804 #endif // TASKQUEUE_STATS
2805 
2806 void G1CollectedHeap::wait_for_root_region_scanning() {
2807   double scan_wait_start = os::elapsedTime();
2808   // We have to wait until the CM threads finish scanning the
2809   // root regions as it's the only way to ensure that all the
2810   // objects on them have been correctly scanned before we start
2811   // moving them during the GC.
2812   bool waited = _cm->root_regions()->wait_until_scan_finished();
2813   double wait_time_ms = 0.0;
2814   if (waited) {
2815     double scan_wait_end = os::elapsedTime();
2816     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2817   }
2818   phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2819 }
2820 
2821 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2822 private:
2823   G1HRPrinter* _hr_printer;
2824 public:
2825   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2826 
2827   virtual bool do_heap_region(HeapRegion* r) {
2828     _hr_printer->cset(r);
2829     return false;
2830   }
2831 };
2832 
2833 void G1CollectedHeap::start_new_collection_set() {
2834   double start = os::elapsedTime();
2835 
2836   collection_set()->start_incremental_building();
2837 
2838   clear_region_attr();
2839 
2840   guarantee(_eden.length() == 0, "eden should have been cleared");
2841   policy()->transfer_survivors_to_cset(survivor());
2842 
2843   // We redo the verification but now wrt to the new CSet which
2844   // has just got initialized after the previous CSet was freed.
2845   _cm->verify_no_collection_set_oops();
2846 
2847   phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2848 }
2849 
2850 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2851 
2852   _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2853   evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2854                                             collection_set()->optional_region_length());
2855 
2856   _cm->verify_no_collection_set_oops();
2857 
2858   if (_hr_printer.is_active()) {
2859     G1PrintCollectionSetClosure cl(&_hr_printer);
2860     _collection_set.iterate(&cl);
2861     _collection_set.iterate_optional(&cl);
2862   }
2863 }
2864 
2865 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2866   if (collector_state()->in_initial_mark_gc()) {
2867     return G1HeapVerifier::G1VerifyConcurrentStart;
2868   } else if (collector_state()->in_young_only_phase()) {
2869     return G1HeapVerifier::G1VerifyYoungNormal;
2870   } else {
2871     return G1HeapVerifier::G1VerifyMixed;
2872   }
2873 }
2874 
2875 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2876   if (VerifyRememberedSets) {
2877     log_info(gc, verify)("[Verifying RemSets before GC]");
2878     VerifyRegionRemSetClosure v_cl;
2879     heap_region_iterate(&v_cl);
2880   }
2881   _verifier->verify_before_gc(type);
2882   _verifier->check_bitmaps("GC Start");
2883 }
2884 
2885 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2886   if (VerifyRememberedSets) {
2887     log_info(gc, verify)("[Verifying RemSets after GC]");
2888     VerifyRegionRemSetClosure v_cl;
2889     heap_region_iterate(&v_cl);
2890   }
2891   _verifier->verify_after_gc(type);
2892   _verifier->check_bitmaps("GC End");
2893 }
2894 
2895 void G1CollectedHeap::expand_heap_after_young_collection(){
2896   size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2897   if (expand_bytes > 0) {
2898     // No need for an ergo logging here,
2899     // expansion_amount() does this when it returns a value > 0.
2900     double expand_ms;
2901     if (!expand(expand_bytes, _workers, &expand_ms)) {
2902       // We failed to expand the heap. Cannot do anything about it.
2903     }
2904     phase_times()->record_expand_heap_time(expand_ms);
2905   }
2906 }
2907 
2908 const char* G1CollectedHeap::young_gc_name() const {
2909   if (collector_state()->in_initial_mark_gc()) {
2910     return "Pause Young (Concurrent Start)";
2911   } else if (collector_state()->in_young_only_phase()) {
2912     if (collector_state()->in_young_gc_before_mixed()) {
2913       return "Pause Young (Prepare Mixed)";
2914     } else {
2915       return "Pause Young (Normal)";
2916     }
2917   } else {
2918     return "Pause Young (Mixed)";
2919   }
2920 }
2921 
2922 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2923   assert_at_safepoint_on_vm_thread();
2924   guarantee(!is_gc_active(), "collection is not reentrant");
2925 
2926   if (GCLocker::check_active_before_gc()) {
2927     return false;
2928   }
2929 
2930   GCIdMark gc_id_mark;
2931 
2932   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2933   ResourceMark rm;
2934 
2935   policy()->note_gc_start();
2936 
2937   _gc_timer_stw->register_gc_start();
2938   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2939 
2940   wait_for_root_region_scanning();
2941 
2942   print_heap_before_gc();
2943   print_heap_regions();
2944   trace_heap_before_gc(_gc_tracer_stw);
2945 
2946   _verifier->verify_region_sets_optional();
2947   _verifier->verify_dirty_young_regions();
2948 
2949   // We should not be doing initial mark unless the conc mark thread is running
2950   if (!_cm_thread->should_terminate()) {
2951     // This call will decide whether this pause is an initial-mark
2952     // pause. If it is, in_initial_mark_gc() will return true
2953     // for the duration of this pause.
2954     policy()->decide_on_conc_mark_initiation();
2955   }
2956 
2957   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2958   assert(!collector_state()->in_initial_mark_gc() ||
2959          collector_state()->in_young_only_phase(), "sanity");
2960   // We also do not allow mixed GCs during marking.
2961   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2962 
2963   // Record whether this pause is an initial mark. When the current
2964   // thread has completed its logging output and it's safe to signal
2965   // the CM thread, the flag's value in the policy has been reset.
2966   bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2967   if (should_start_conc_mark) {
2968     _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2969   }
2970 
2971   // Inner scope for scope based logging, timers, and stats collection
2972   {
2973     G1EvacuationInfo evacuation_info;
2974 
2975     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2976 
2977     GCTraceCPUTime tcpu;
2978 
2979     GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
2980 
2981     uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
2982                                                             workers()->active_workers(),
2983                                                             Threads::number_of_non_daemon_threads());
2984     active_workers = workers()->update_active_workers(active_workers);
2985     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2986 
2987     G1MonitoringScope ms(g1mm(),
2988                          false /* full_gc */,
2989                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2990 
2991     G1HeapTransition heap_transition(this);
2992     size_t heap_used_bytes_before_gc = used();
2993 
2994     {
2995       IsGCActiveMark x;
2996 
2997       gc_prologue(false);
2998 
2999       G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3000       verify_before_young_collection(verify_type);
3001 
3002       {
3003         // The elapsed time induced by the start time below deliberately elides
3004         // the possible verification above.
3005         double sample_start_time_sec = os::elapsedTime();
3006 
3007         // Please see comment in g1CollectedHeap.hpp and
3008         // G1CollectedHeap::ref_processing_init() to see how
3009         // reference processing currently works in G1.
3010         _ref_processor_stw->enable_discovery();
3011 
3012         // We want to temporarily turn off discovery by the
3013         // CM ref processor, if necessary, and turn it back on
3014         // on again later if we do. Using a scoped
3015         // NoRefDiscovery object will do this.
3016         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3017 
3018         policy()->record_collection_pause_start(sample_start_time_sec);
3019 
3020         // Forget the current allocation region (we might even choose it to be part
3021         // of the collection set!).
3022         _allocator->release_mutator_alloc_region();
3023 
3024         calculate_collection_set(evacuation_info, target_pause_time_ms);
3025 
3026         G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3027         G1ParScanThreadStateSet per_thread_states(this,
3028                                                   &rdcqs,
3029                                                   workers()->active_workers(),
3030                                                   collection_set()->young_region_length(),
3031                                                   collection_set()->optional_region_length());
3032         pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3033 
3034         // Actually do the work...
3035         evacuate_initial_collection_set(&per_thread_states);
3036 
3037         if (_collection_set.optional_region_length() != 0) {
3038           evacuate_optional_collection_set(&per_thread_states);
3039         }
3040         post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3041 
3042         start_new_collection_set();
3043 
3044         _survivor_evac_stats.adjust_desired_plab_sz();
3045         _old_evac_stats.adjust_desired_plab_sz();
3046 
3047         if (should_start_conc_mark) {
3048           // We have to do this before we notify the CM threads that
3049           // they can start working to make sure that all the
3050           // appropriate initialization is done on the CM object.
3051           concurrent_mark()->post_initial_mark();
3052           // Note that we don't actually trigger the CM thread at
3053           // this point. We do that later when we're sure that
3054           // the current thread has completed its logging output.
3055         }
3056 
3057         allocate_dummy_regions();
3058 
3059         _allocator->init_mutator_alloc_region();
3060 
3061         expand_heap_after_young_collection();
3062 
3063         double sample_end_time_sec = os::elapsedTime();
3064         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3065         policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc);
3066       }
3067 
3068       verify_after_young_collection(verify_type);
3069 
3070 #ifdef TRACESPINNING
3071       ParallelTaskTerminator::print_termination_counts();
3072 #endif
3073 
3074       gc_epilogue(false);
3075     }
3076 
3077     // Print the remainder of the GC log output.
3078     if (evacuation_failed()) {
3079       log_info(gc)("To-space exhausted");
3080     }
3081 
3082     policy()->print_phases();
3083     heap_transition.print();
3084 
3085     _hrm->verify_optional();
3086     _verifier->verify_region_sets_optional();
3087 
3088     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3089     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3090 
3091     print_heap_after_gc();
3092     print_heap_regions();
3093     trace_heap_after_gc(_gc_tracer_stw);
3094 
3095     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3096     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3097     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3098     // before any GC notifications are raised.
3099     g1mm()->update_sizes();
3100 
3101     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3102     _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3103     _gc_timer_stw->register_gc_end();
3104     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3105   }
3106   // It should now be safe to tell the concurrent mark thread to start
3107   // without its logging output interfering with the logging output
3108   // that came from the pause.
3109 
3110   if (should_start_conc_mark) {
3111     // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3112     // thread(s) could be running concurrently with us. Make sure that anything
3113     // after this point does not assume that we are the only GC thread running.
3114     // Note: of course, the actual marking work will not start until the safepoint
3115     // itself is released in SuspendibleThreadSet::desynchronize().
3116     do_concurrent_mark();
3117   }
3118 
3119   return true;
3120 }
3121 
3122 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3123   G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3124   workers()->run_task(&rsfp_task);
3125 }
3126 
3127 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3128   double remove_self_forwards_start = os::elapsedTime();
3129 
3130   remove_self_forwarding_pointers(rdcqs);
3131   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3132   _preserved_marks_set.restore(&task_executor);
3133 
3134   phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3135 }
3136 
3137 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3138   if (!_evacuation_failed) {
3139     _evacuation_failed = true;
3140   }
3141 
3142   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3143   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3144 }
3145 
3146 bool G1ParEvacuateFollowersClosure::offer_termination() {
3147   EventGCPhaseParallel event;
3148   G1ParScanThreadState* const pss = par_scan_state();
3149   start_term_time();
3150   const bool res = terminator()->offer_termination();
3151   end_term_time();
3152   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3153   return res;
3154 }
3155 
3156 void G1ParEvacuateFollowersClosure::do_void() {
3157   EventGCPhaseParallel event;
3158   G1ParScanThreadState* const pss = par_scan_state();
3159   pss->trim_queue();
3160   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3161   do {
3162     EventGCPhaseParallel event;
3163     pss->steal_and_trim_queue(queues());
3164     event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3165   } while (!offer_termination());
3166 }
3167 
3168 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3169                                         bool class_unloading_occurred) {
3170   uint num_workers = workers()->active_workers();
3171   G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3172   workers()->run_task(&unlink_task);
3173 }
3174 
3175 // Clean string dedup data structures.
3176 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3177 // record the durations of the phases. Hence the almost-copy.
3178 class G1StringDedupCleaningTask : public AbstractGangTask {
3179   BoolObjectClosure* _is_alive;
3180   OopClosure* _keep_alive;
3181   G1GCPhaseTimes* _phase_times;
3182 
3183 public:
3184   G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3185                             OopClosure* keep_alive,
3186                             G1GCPhaseTimes* phase_times) :
3187     AbstractGangTask("Partial Cleaning Task"),
3188     _is_alive(is_alive),
3189     _keep_alive(keep_alive),
3190     _phase_times(phase_times)
3191   {
3192     assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3193     StringDedup::gc_prologue(true);
3194   }
3195 
3196   ~G1StringDedupCleaningTask() {
3197     StringDedup::gc_epilogue();
3198   }
3199 
3200   void work(uint worker_id) {
3201     StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3202     {
3203       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3204       StringDedupQueue::unlink_or_oops_do(&cl);
3205     }
3206     {
3207       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3208       StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3209     }
3210   }
3211 };
3212 
3213 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3214                                             OopClosure* keep_alive,
3215                                             G1GCPhaseTimes* phase_times) {
3216   G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3217   workers()->run_task(&cl);
3218 }
3219 
3220 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3221  private:
3222   G1RedirtyCardsQueueSet* _qset;
3223   G1CollectedHeap* _g1h;
3224   BufferNode* volatile _nodes;
3225 
3226   void apply(G1CardTableEntryClosure* cl, BufferNode* node, uint worker_id) {
3227     void** buf = BufferNode::make_buffer_from_node(node);
3228     size_t limit = _qset->buffer_size();
3229     for (size_t i = node->index(); i < limit; ++i) {
3230       CardTable::CardValue* card_ptr = static_cast<CardTable::CardValue*>(buf[i]);
3231       bool result = cl->do_card_ptr(card_ptr, worker_id);
3232       assert(result, "Closure should always return true");
3233     }
3234   }
3235 
3236   void par_apply(G1CardTableEntryClosure* cl, uint worker_id) {
3237     BufferNode* next = Atomic::load(&_nodes);
3238     while (next != NULL) {
3239       BufferNode* node = next;
3240       next = Atomic::cmpxchg(node->next(), &_nodes, node);
3241       if (next == node) {
3242         apply(cl, node, worker_id);
3243         next = node->next();
3244       }
3245     }
3246   }
3247 
3248  public:
3249   G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3250     AbstractGangTask("Redirty Cards"),
3251     _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3252 
3253   virtual void work(uint worker_id) {
3254     G1GCPhaseTimes* p = _g1h->phase_times();
3255     G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3256 
3257     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3258     par_apply(&cl, worker_id);
3259 
3260     p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3261   }
3262 };
3263 
3264 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3265   double redirty_logged_cards_start = os::elapsedTime();
3266 
3267   G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3268   workers()->run_task(&redirty_task);
3269 
3270   G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3271   dcq.merge_bufferlists(rdcqs);
3272 
3273   phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3274 }
3275 
3276 // Weak Reference Processing support
3277 
3278 bool G1STWIsAliveClosure::do_object_b(oop p) {
3279   // An object is reachable if it is outside the collection set,
3280   // or is inside and copied.
3281   return !_g1h->is_in_cset(p) || p->is_forwarded();
3282 }
3283 
3284 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3285   assert(obj != NULL, "must not be NULL");
3286   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3287   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3288   // may falsely indicate that this is not the case here: however the collection set only
3289   // contains old regions when concurrent mark is not running.
3290   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3291 }
3292 
3293 // Non Copying Keep Alive closure
3294 class G1KeepAliveClosure: public OopClosure {
3295   G1CollectedHeap*_g1h;
3296 public:
3297   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3298   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3299   void do_oop(oop* p) {
3300     oop obj = *p;
3301     assert(obj != NULL, "the caller should have filtered out NULL values");
3302 
3303     const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3304     if (!region_attr.is_in_cset_or_humongous()) {
3305       return;
3306     }
3307     if (region_attr.is_in_cset()) {
3308       assert( obj->is_forwarded(), "invariant" );
3309       *p = obj->forwardee();
3310     } else {
3311       assert(!obj->is_forwarded(), "invariant" );
3312       assert(region_attr.is_humongous(),
3313              "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3314      _g1h->set_humongous_is_live(obj);
3315     }
3316   }
3317 };
3318 
3319 // Copying Keep Alive closure - can be called from both
3320 // serial and parallel code as long as different worker
3321 // threads utilize different G1ParScanThreadState instances
3322 // and different queues.
3323 
3324 class G1CopyingKeepAliveClosure: public OopClosure {
3325   G1CollectedHeap*         _g1h;
3326   G1ParScanThreadState*    _par_scan_state;
3327 
3328 public:
3329   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3330                             G1ParScanThreadState* pss):
3331     _g1h(g1h),
3332     _par_scan_state(pss)
3333   {}
3334 
3335   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3336   virtual void do_oop(      oop* p) { do_oop_work(p); }
3337 
3338   template <class T> void do_oop_work(T* p) {
3339     oop obj = RawAccess<>::oop_load(p);
3340 
3341     if (_g1h->is_in_cset_or_humongous(obj)) {
3342       // If the referent object has been forwarded (either copied
3343       // to a new location or to itself in the event of an
3344       // evacuation failure) then we need to update the reference
3345       // field and, if both reference and referent are in the G1
3346       // heap, update the RSet for the referent.
3347       //
3348       // If the referent has not been forwarded then we have to keep
3349       // it alive by policy. Therefore we have copy the referent.
3350       //
3351       // When the queue is drained (after each phase of reference processing)
3352       // the object and it's followers will be copied, the reference field set
3353       // to point to the new location, and the RSet updated.
3354       _par_scan_state->push_on_queue(p);
3355     }
3356   }
3357 };
3358 
3359 // Serial drain queue closure. Called as the 'complete_gc'
3360 // closure for each discovered list in some of the
3361 // reference processing phases.
3362 
3363 class G1STWDrainQueueClosure: public VoidClosure {
3364 protected:
3365   G1CollectedHeap* _g1h;
3366   G1ParScanThreadState* _par_scan_state;
3367 
3368   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3369 
3370 public:
3371   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3372     _g1h(g1h),
3373     _par_scan_state(pss)
3374   { }
3375 
3376   void do_void() {
3377     G1ParScanThreadState* const pss = par_scan_state();
3378     pss->trim_queue();
3379   }
3380 };
3381 
3382 // Parallel Reference Processing closures
3383 
3384 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3385 // processing during G1 evacuation pauses.
3386 
3387 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3388 private:
3389   G1CollectedHeap*          _g1h;
3390   G1ParScanThreadStateSet*  _pss;
3391   RefToScanQueueSet*        _queues;
3392   WorkGang*                 _workers;
3393 
3394 public:
3395   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3396                            G1ParScanThreadStateSet* per_thread_states,
3397                            WorkGang* workers,
3398                            RefToScanQueueSet *task_queues) :
3399     _g1h(g1h),
3400     _pss(per_thread_states),
3401     _queues(task_queues),
3402     _workers(workers)
3403   {
3404     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3405   }
3406 
3407   // Executes the given task using concurrent marking worker threads.
3408   virtual void execute(ProcessTask& task, uint ergo_workers);
3409 };
3410 
3411 // Gang task for possibly parallel reference processing
3412 
3413 class G1STWRefProcTaskProxy: public AbstractGangTask {
3414   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3415   ProcessTask&     _proc_task;
3416   G1CollectedHeap* _g1h;
3417   G1ParScanThreadStateSet* _pss;
3418   RefToScanQueueSet* _task_queues;
3419   ParallelTaskTerminator* _terminator;
3420 
3421 public:
3422   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3423                         G1CollectedHeap* g1h,
3424                         G1ParScanThreadStateSet* per_thread_states,
3425                         RefToScanQueueSet *task_queues,
3426                         ParallelTaskTerminator* terminator) :
3427     AbstractGangTask("Process reference objects in parallel"),
3428     _proc_task(proc_task),
3429     _g1h(g1h),
3430     _pss(per_thread_states),
3431     _task_queues(task_queues),
3432     _terminator(terminator)
3433   {}
3434 
3435   virtual void work(uint worker_id) {
3436     // The reference processing task executed by a single worker.
3437     ResourceMark rm;
3438     HandleMark   hm;
3439 
3440     G1STWIsAliveClosure is_alive(_g1h);
3441 
3442     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3443     pss->set_ref_discoverer(NULL);
3444 
3445     // Keep alive closure.
3446     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3447 
3448     // Complete GC closure
3449     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3450 
3451     // Call the reference processing task's work routine.
3452     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3453 
3454     // Note we cannot assert that the refs array is empty here as not all
3455     // of the processing tasks (specifically phase2 - pp2_work) execute
3456     // the complete_gc closure (which ordinarily would drain the queue) so
3457     // the queue may not be empty.
3458   }
3459 };
3460 
3461 // Driver routine for parallel reference processing.
3462 // Creates an instance of the ref processing gang
3463 // task and has the worker threads execute it.
3464 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3465   assert(_workers != NULL, "Need parallel worker threads.");
3466 
3467   assert(_workers->active_workers() >= ergo_workers,
3468          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3469          ergo_workers, _workers->active_workers());
3470   TaskTerminator terminator(ergo_workers, _queues);
3471   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3472 
3473   _workers->run_task(&proc_task_proxy, ergo_workers);
3474 }
3475 
3476 // End of weak reference support closures
3477 
3478 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3479   double ref_proc_start = os::elapsedTime();
3480 
3481   ReferenceProcessor* rp = _ref_processor_stw;
3482   assert(rp->discovery_enabled(), "should have been enabled");
3483 
3484   // Closure to test whether a referent is alive.
3485   G1STWIsAliveClosure is_alive(this);
3486 
3487   // Even when parallel reference processing is enabled, the processing
3488   // of JNI refs is serial and performed serially by the current thread
3489   // rather than by a worker. The following PSS will be used for processing
3490   // JNI refs.
3491 
3492   // Use only a single queue for this PSS.
3493   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3494   pss->set_ref_discoverer(NULL);
3495   assert(pss->queue_is_empty(), "pre-condition");
3496 
3497   // Keep alive closure.
3498   G1CopyingKeepAliveClosure keep_alive(this, pss);
3499 
3500   // Serial Complete GC closure
3501   G1STWDrainQueueClosure drain_queue(this, pss);
3502 
3503   // Setup the soft refs policy...
3504   rp->setup_policy(false);
3505 
3506   ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3507 
3508   ReferenceProcessorStats stats;
3509   if (!rp->processing_is_mt()) {
3510     // Serial reference processing...
3511     stats = rp->process_discovered_references(&is_alive,
3512                                               &keep_alive,
3513                                               &drain_queue,
3514                                               NULL,
3515                                               pt);
3516   } else {
3517     uint no_of_gc_workers = workers()->active_workers();
3518 
3519     // Parallel reference processing
3520     assert(no_of_gc_workers <= rp->max_num_queues(),
3521            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3522            no_of_gc_workers,  rp->max_num_queues());
3523 
3524     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3525     stats = rp->process_discovered_references(&is_alive,
3526                                               &keep_alive,
3527                                               &drain_queue,
3528                                               &par_task_executor,
3529                                               pt);
3530   }
3531 
3532   _gc_tracer_stw->report_gc_reference_stats(stats);
3533 
3534   // We have completed copying any necessary live referent objects.
3535   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3536 
3537   make_pending_list_reachable();
3538 
3539   assert(!rp->discovery_enabled(), "Postcondition");
3540   rp->verify_no_references_recorded();
3541 
3542   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3543   phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3544 }
3545 
3546 void G1CollectedHeap::make_pending_list_reachable() {
3547   if (collector_state()->in_initial_mark_gc()) {
3548     oop pll_head = Universe::reference_pending_list();
3549     if (pll_head != NULL) {
3550       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3551       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3552     }
3553   }
3554 }
3555 
3556 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3557   double merge_pss_time_start = os::elapsedTime();
3558   per_thread_states->flush();
3559   phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3560 }
3561 
3562 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3563   _expand_heap_after_alloc_failure = true;
3564   _evacuation_failed = false;
3565 
3566   // Disable the hot card cache.
3567   _hot_card_cache->reset_hot_cache_claimed_index();
3568   _hot_card_cache->set_use_cache(false);
3569 
3570   // Initialize the GC alloc regions.
3571   _allocator->init_gc_alloc_regions(evacuation_info);
3572 
3573   {
3574     Ticks start = Ticks::now();
3575     rem_set()->prepare_for_scan_heap_roots();
3576     phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3577   }
3578 
3579   register_regions_with_region_attr();
3580   assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3581 
3582   _preserved_marks_set.assert_empty();
3583 
3584 #if COMPILER2_OR_JVMCI
3585   DerivedPointerTable::clear();
3586 #endif
3587 
3588   // InitialMark needs claim bits to keep track of the marked-through CLDs.
3589   if (collector_state()->in_initial_mark_gc()) {
3590     concurrent_mark()->pre_initial_mark();
3591 
3592     double start_clear_claimed_marks = os::elapsedTime();
3593 
3594     ClassLoaderDataGraph::clear_claimed_marks();
3595 
3596     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3597     phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3598   }
3599 
3600   // Should G1EvacuationFailureALot be in effect for this GC?
3601   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3602 }
3603 
3604 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3605 protected:
3606   G1CollectedHeap* _g1h;
3607   G1ParScanThreadStateSet* _per_thread_states;
3608   RefToScanQueueSet* _task_queues;
3609   TaskTerminator _terminator;
3610   uint _num_workers;
3611 
3612   void evacuate_live_objects(G1ParScanThreadState* pss,
3613                              uint worker_id,
3614                              G1GCPhaseTimes::GCParPhases objcopy_phase,
3615                              G1GCPhaseTimes::GCParPhases termination_phase) {
3616     G1GCPhaseTimes* p = _g1h->phase_times();
3617 
3618     Ticks start = Ticks::now();
3619     G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3620     cl.do_void();
3621 
3622     assert(pss->queue_is_empty(), "should be empty");
3623 
3624     Tickspan evac_time = (Ticks::now() - start);
3625     p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3626 
3627     p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste);
3628     p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste);
3629 
3630     if (termination_phase == G1GCPhaseTimes::Termination) {
3631       p->record_time_secs(termination_phase, worker_id, cl.term_time());
3632       p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3633     } else {
3634       p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3635       p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3636     }
3637     assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3638   }
3639 
3640   virtual void start_work(uint worker_id) { }
3641 
3642   virtual void end_work(uint worker_id) { }
3643 
3644   virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3645 
3646   virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3647 
3648 public:
3649   G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3650     AbstractGangTask(name),
3651     _g1h(G1CollectedHeap::heap()),
3652     _per_thread_states(per_thread_states),
3653     _task_queues(task_queues),
3654     _terminator(num_workers, _task_queues),
3655     _num_workers(num_workers)
3656   { }
3657 
3658   void work(uint worker_id) {
3659     start_work(worker_id);
3660 
3661     {
3662       ResourceMark rm;
3663       HandleMark   hm;
3664 
3665       G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3666       pss->set_ref_discoverer(_g1h->ref_processor_stw());
3667 
3668       scan_roots(pss, worker_id);
3669       evacuate_live_objects(pss, worker_id);
3670     }
3671 
3672     end_work(worker_id);
3673   }
3674 };
3675 
3676 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3677   G1RootProcessor* _root_processor;
3678 
3679   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3680     _root_processor->evacuate_roots(pss, worker_id);
3681     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3682     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3683   }
3684 
3685   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3686     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3687   }
3688 
3689   void start_work(uint worker_id) {
3690     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3691   }
3692 
3693   void end_work(uint worker_id) {
3694     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3695   }
3696 
3697 public:
3698   G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3699                         G1ParScanThreadStateSet* per_thread_states,
3700                         RefToScanQueueSet* task_queues,
3701                         G1RootProcessor* root_processor,
3702                         uint num_workers) :
3703     G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3704     _root_processor(root_processor)
3705   { }
3706 };
3707 
3708 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3709   G1GCPhaseTimes* p = phase_times();
3710 
3711   {
3712     Ticks start = Ticks::now();
3713     rem_set()->merge_heap_roots(true /* initial_evacuation */);
3714     p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3715   }
3716 
3717   Tickspan task_time;
3718   const uint num_workers = workers()->active_workers();
3719 
3720   Ticks start_processing = Ticks::now();
3721   {
3722     G1RootProcessor root_processor(this, num_workers);
3723     G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3724     task_time = run_task(&g1_par_task);
3725     // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3726     // To extract its code root fixup time we measure total time of this scope and
3727     // subtract from the time the WorkGang task took.
3728   }
3729   Tickspan total_processing = Ticks::now() - start_processing;
3730 
3731   p->record_initial_evac_time(task_time.seconds() * 1000.0);
3732   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3733 }
3734 
3735 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3736 
3737   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3738     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3739     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3740   }
3741 
3742   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3743     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3744   }
3745 
3746 public:
3747   G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3748                                 RefToScanQueueSet* queues,
3749                                 uint num_workers) :
3750     G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3751   }
3752 };
3753 
3754 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3755   class G1MarkScope : public MarkScope { };
3756 
3757   Tickspan task_time;
3758 
3759   Ticks start_processing = Ticks::now();
3760   {
3761     G1MarkScope code_mark_scope;
3762     G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3763     task_time = run_task(&task);
3764     // See comment in evacuate_collection_set() for the reason of the scope.
3765   }
3766   Tickspan total_processing = Ticks::now() - start_processing;
3767 
3768   G1GCPhaseTimes* p = phase_times();
3769   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3770 }
3771 
3772 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3773   const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3774 
3775   while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3776 
3777     double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3778     double time_left_ms = MaxGCPauseMillis - time_used_ms;
3779 
3780     if (time_left_ms < 0 ||
3781         !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3782       log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3783                                 _collection_set.optional_region_length(), time_left_ms);
3784       break;
3785     }
3786 
3787     {
3788       Ticks start = Ticks::now();
3789       rem_set()->merge_heap_roots(false /* initial_evacuation */);
3790       phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3791     }
3792 
3793     {
3794       Ticks start = Ticks::now();
3795       evacuate_next_optional_regions(per_thread_states);
3796       phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3797     }
3798   }
3799 
3800   _collection_set.abandon_optional_collection_set(per_thread_states);
3801 }
3802 
3803 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3804                                                    G1RedirtyCardsQueueSet* rdcqs,
3805                                                    G1ParScanThreadStateSet* per_thread_states) {
3806   rem_set()->cleanup_after_scan_heap_roots();
3807 
3808   // Process any discovered reference objects - we have
3809   // to do this _before_ we retire the GC alloc regions
3810   // as we may have to copy some 'reachable' referent
3811   // objects (and their reachable sub-graphs) that were
3812   // not copied during the pause.
3813   process_discovered_references(per_thread_states);
3814 
3815   G1STWIsAliveClosure is_alive(this);
3816   G1KeepAliveClosure keep_alive(this);
3817 
3818   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3819                               phase_times()->weak_phase_times());
3820 
3821   if (G1StringDedup::is_enabled()) {
3822     double string_dedup_time_ms = os::elapsedTime();
3823 
3824     string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
3825 
3826     double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3827     phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3828   }
3829 
3830   _allocator->release_gc_alloc_regions(evacuation_info);
3831 
3832   if (evacuation_failed()) {
3833     restore_after_evac_failure(rdcqs);
3834 
3835     // Reset the G1EvacuationFailureALot counters and flags
3836     NOT_PRODUCT(reset_evacuation_should_fail();)
3837 
3838     double recalculate_used_start = os::elapsedTime();
3839     set_used(recalculate_used());
3840     phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3841 
3842     if (_archive_allocator != NULL) {
3843       _archive_allocator->clear_used();
3844     }
3845     for (uint i = 0; i < ParallelGCThreads; i++) {
3846       if (_evacuation_failed_info_array[i].has_failed()) {
3847         _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3848       }
3849     }
3850   } else {
3851     // The "used" of the the collection set have already been subtracted
3852     // when they were freed.  Add in the bytes evacuated.
3853     increase_used(policy()->bytes_copied_during_gc());
3854   }
3855 
3856   _preserved_marks_set.assert_empty();
3857 
3858   merge_per_thread_state_info(per_thread_states);
3859 
3860   // Reset and re-enable the hot card cache.
3861   // Note the counts for the cards in the regions in the
3862   // collection set are reset when the collection set is freed.
3863   _hot_card_cache->reset_hot_cache();
3864   _hot_card_cache->set_use_cache(true);
3865 
3866   purge_code_root_memory();
3867 
3868   redirty_logged_cards(rdcqs);
3869 
3870   free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3871 
3872   eagerly_reclaim_humongous_regions();
3873 
3874   record_obj_copy_mem_stats();
3875 
3876   evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3877   evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
3878 
3879 #if COMPILER2_OR_JVMCI
3880   double start = os::elapsedTime();
3881   DerivedPointerTable::update_pointers();
3882   phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3883 #endif
3884   policy()->print_age_table();
3885 }
3886 
3887 void G1CollectedHeap::record_obj_copy_mem_stats() {
3888   policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3889 
3890   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3891                                                create_g1_evac_summary(&_old_evac_stats));
3892 }
3893 
3894 void G1CollectedHeap::free_region(HeapRegion* hr,
3895                                   FreeRegionList* free_list,
3896                                   bool skip_remset,
3897                                   bool skip_hot_card_cache,
3898                                   bool locked) {
3899   assert(!hr->is_free(), "the region should not be free");
3900   assert(!hr->is_empty(), "the region should not be empty");
3901   assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3902   assert(free_list != NULL, "pre-condition");
3903 
3904   if (G1VerifyBitmaps) {
3905     MemRegion mr(hr->bottom(), hr->end());
3906     concurrent_mark()->clear_range_in_prev_bitmap(mr);
3907   }
3908 
3909   // Clear the card counts for this region.
3910   // Note: we only need to do this if the region is not young
3911   // (since we don't refine cards in young regions).
3912   if (!skip_hot_card_cache && !hr->is_young()) {
3913     _hot_card_cache->reset_card_counts(hr);
3914   }
3915   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3916   _policy->remset_tracker()->update_at_free(hr);
3917   free_list->add_ordered(hr);
3918 }
3919 
3920 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3921                                             FreeRegionList* free_list) {
3922   assert(hr->is_humongous(), "this is only for humongous regions");
3923   assert(free_list != NULL, "pre-condition");
3924   hr->clear_humongous();
3925   free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3926 }
3927 
3928 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3929                                            const uint humongous_regions_removed) {
3930   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3931     MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3932     _old_set.bulk_remove(old_regions_removed);
3933     _humongous_set.bulk_remove(humongous_regions_removed);
3934   }
3935 
3936 }
3937 
3938 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3939   assert(list != NULL, "list can't be null");
3940   if (!list->is_empty()) {
3941     MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3942     _hrm->insert_list_into_free_list(list);
3943   }
3944 }
3945 
3946 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3947   decrease_used(bytes);
3948 }
3949 
3950 class G1FreeCollectionSetTask : public AbstractGangTask {
3951 private:
3952 
3953   // Closure applied to all regions in the collection set to do work that needs to
3954   // be done serially in a single thread.
3955   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3956   private:
3957     G1EvacuationInfo* _evacuation_info;
3958     const size_t* _surviving_young_words;
3959 
3960     // Bytes used in successfully evacuated regions before the evacuation.
3961     size_t _before_used_bytes;
3962     // Bytes used in unsucessfully evacuated regions before the evacuation
3963     size_t _after_used_bytes;
3964 
3965     size_t _bytes_allocated_in_old_since_last_gc;
3966 
3967     size_t _failure_used_words;
3968     size_t _failure_waste_words;
3969 
3970     FreeRegionList _local_free_list;
3971   public:
3972     G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3973       HeapRegionClosure(),
3974       _evacuation_info(evacuation_info),
3975       _surviving_young_words(surviving_young_words),
3976       _before_used_bytes(0),
3977       _after_used_bytes(0),
3978       _bytes_allocated_in_old_since_last_gc(0),
3979       _failure_used_words(0),
3980       _failure_waste_words(0),
3981       _local_free_list("Local Region List for CSet Freeing") {
3982     }
3983 
3984     virtual bool do_heap_region(HeapRegion* r) {
3985       G1CollectedHeap* g1h = G1CollectedHeap::heap();
3986 
3987       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3988       g1h->clear_region_attr(r);
3989 
3990       if (r->is_young()) {
3991         assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(),
3992                "Young index %u is wrong for region %u of type %s with %u young regions",
3993                r->young_index_in_cset(),
3994                r->hrm_index(),
3995                r->get_type_str(),
3996                g1h->collection_set()->young_region_length());
3997         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
3998         r->record_surv_words_in_group(words_survived);
3999       }
4000 
4001       if (!r->evacuation_failed()) {
4002         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4003         _before_used_bytes += r->used();
4004         g1h->free_region(r,
4005                          &_local_free_list,
4006                          true, /* skip_remset */
4007                          true, /* skip_hot_card_cache */
4008                          true  /* locked */);
4009       } else {
4010         r->uninstall_surv_rate_group();
4011         r->clear_young_index_in_cset();
4012         r->set_evacuation_failed(false);
4013         // When moving a young gen region to old gen, we "allocate" that whole region
4014         // there. This is in addition to any already evacuated objects. Notify the
4015         // policy about that.
4016         // Old gen regions do not cause an additional allocation: both the objects
4017         // still in the region and the ones already moved are accounted for elsewhere.
4018         if (r->is_young()) {
4019           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4020         }
4021         // The region is now considered to be old.
4022         r->set_old();
4023         // Do some allocation statistics accounting. Regions that failed evacuation
4024         // are always made old, so there is no need to update anything in the young
4025         // gen statistics, but we need to update old gen statistics.
4026         size_t used_words = r->marked_bytes() / HeapWordSize;
4027 
4028         _failure_used_words += used_words;
4029         _failure_waste_words += HeapRegion::GrainWords - used_words;
4030 
4031         g1h->old_set_add(r);
4032         _after_used_bytes += r->used();
4033       }
4034       return false;
4035     }
4036 
4037     void complete_work() {
4038       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4039 
4040       _evacuation_info->set_regions_freed(_local_free_list.length());
4041       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4042 
4043       g1h->prepend_to_freelist(&_local_free_list);
4044       g1h->decrement_summary_bytes(_before_used_bytes);
4045 
4046       G1Policy* policy = g1h->policy();
4047       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4048 
4049       g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4050     }
4051   };
4052 
4053   G1CollectionSet* _collection_set;
4054   G1SerialFreeCollectionSetClosure _cl;
4055   const size_t* _surviving_young_words;
4056 
4057   size_t _rs_length;
4058 
4059   volatile jint _serial_work_claim;
4060 
4061   struct WorkItem {
4062     uint region_idx;
4063     bool is_young;
4064     bool evacuation_failed;
4065 
4066     WorkItem(HeapRegion* r) {
4067       region_idx = r->hrm_index();
4068       is_young = r->is_young();
4069       evacuation_failed = r->evacuation_failed();
4070     }
4071   };
4072 
4073   volatile size_t _parallel_work_claim;
4074   size_t _num_work_items;
4075   WorkItem* _work_items;
4076 
4077   void do_serial_work() {
4078     // Need to grab the lock to be allowed to modify the old region list.
4079     MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4080     _collection_set->iterate(&_cl);
4081   }
4082 
4083   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4084     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4085 
4086     HeapRegion* r = g1h->region_at(region_idx);
4087     assert(!g1h->is_on_master_free_list(r), "sanity");
4088 
4089     Atomic::add(r->rem_set()->occupied_locked(), &_rs_length);
4090 
4091     if (!is_young) {
4092       g1h->_hot_card_cache->reset_card_counts(r);
4093     }
4094 
4095     if (!evacuation_failed) {
4096       r->rem_set()->clear_locked();
4097     }
4098   }
4099 
4100   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4101   private:
4102     size_t _cur_idx;
4103     WorkItem* _work_items;
4104   public:
4105     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4106 
4107     virtual bool do_heap_region(HeapRegion* r) {
4108       _work_items[_cur_idx++] = WorkItem(r);
4109       return false;
4110     }
4111   };
4112 
4113   void prepare_work() {
4114     G1PrepareFreeCollectionSetClosure cl(_work_items);
4115     _collection_set->iterate(&cl);
4116   }
4117 
4118   void complete_work() {
4119     _cl.complete_work();
4120 
4121     G1Policy* policy = G1CollectedHeap::heap()->policy();
4122     policy->record_max_rs_length(_rs_length);
4123     policy->cset_regions_freed();
4124   }
4125 public:
4126   G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4127     AbstractGangTask("G1 Free Collection Set"),
4128     _collection_set(collection_set),
4129     _cl(evacuation_info, surviving_young_words),
4130     _surviving_young_words(surviving_young_words),
4131     _rs_length(0),
4132     _serial_work_claim(0),
4133     _parallel_work_claim(0),
4134     _num_work_items(collection_set->region_length()),
4135     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4136     prepare_work();
4137   }
4138 
4139   ~G1FreeCollectionSetTask() {
4140     complete_work();
4141     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4142   }
4143 
4144   // Chunk size for work distribution. The chosen value has been determined experimentally
4145   // to be a good tradeoff between overhead and achievable parallelism.
4146   static uint chunk_size() { return 32; }
4147 
4148   virtual void work(uint worker_id) {
4149     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4150 
4151     // Claim serial work.
4152     if (_serial_work_claim == 0) {
4153       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4154       if (value == 0) {
4155         double serial_time = os::elapsedTime();
4156         do_serial_work();
4157         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4158       }
4159     }
4160 
4161     // Start parallel work.
4162     double young_time = 0.0;
4163     bool has_young_time = false;
4164     double non_young_time = 0.0;
4165     bool has_non_young_time = false;
4166 
4167     while (true) {
4168       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4169       size_t cur = end - chunk_size();
4170 
4171       if (cur >= _num_work_items) {
4172         break;
4173       }
4174 
4175       EventGCPhaseParallel event;
4176       double start_time = os::elapsedTime();
4177 
4178       end = MIN2(end, _num_work_items);
4179 
4180       for (; cur < end; cur++) {
4181         bool is_young = _work_items[cur].is_young;
4182 
4183         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4184 
4185         double end_time = os::elapsedTime();
4186         double time_taken = end_time - start_time;
4187         if (is_young) {
4188           young_time += time_taken;
4189           has_young_time = true;
4190           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4191         } else {
4192           non_young_time += time_taken;
4193           has_non_young_time = true;
4194           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4195         }
4196         start_time = end_time;
4197       }
4198     }
4199 
4200     if (has_young_time) {
4201       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4202     }
4203     if (has_non_young_time) {
4204       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4205     }
4206   }
4207 };
4208 
4209 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4210   _eden.clear();
4211 
4212   double free_cset_start_time = os::elapsedTime();
4213 
4214   {
4215     uint const num_regions = _collection_set.region_length();
4216     uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U);
4217     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4218 
4219     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4220 
4221     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4222                         cl.name(), num_workers, num_regions);
4223     workers()->run_task(&cl, num_workers);
4224   }
4225   phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4226 
4227   collection_set->clear();
4228 }
4229 
4230 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4231  private:
4232   FreeRegionList* _free_region_list;
4233   HeapRegionSet* _proxy_set;
4234   uint _humongous_objects_reclaimed;
4235   uint _humongous_regions_reclaimed;
4236   size_t _freed_bytes;
4237  public:
4238 
4239   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4240     _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4241   }
4242 
4243   virtual bool do_heap_region(HeapRegion* r) {
4244     if (!r->is_starts_humongous()) {
4245       return false;
4246     }
4247 
4248     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4249 
4250     oop obj = (oop)r->bottom();
4251     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4252 
4253     // The following checks whether the humongous object is live are sufficient.
4254     // The main additional check (in addition to having a reference from the roots
4255     // or the young gen) is whether the humongous object has a remembered set entry.
4256     //
4257     // A humongous object cannot be live if there is no remembered set for it
4258     // because:
4259     // - there can be no references from within humongous starts regions referencing
4260     // the object because we never allocate other objects into them.
4261     // (I.e. there are no intra-region references that may be missed by the
4262     // remembered set)
4263     // - as soon there is a remembered set entry to the humongous starts region
4264     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4265     // until the end of a concurrent mark.
4266     //
4267     // It is not required to check whether the object has been found dead by marking
4268     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4269     // all objects allocated during that time are considered live.
4270     // SATB marking is even more conservative than the remembered set.
4271     // So if at this point in the collection there is no remembered set entry,
4272     // nobody has a reference to it.
4273     // At the start of collection we flush all refinement logs, and remembered sets
4274     // are completely up-to-date wrt to references to the humongous object.
4275     //
4276     // Other implementation considerations:
4277     // - never consider object arrays at this time because they would pose
4278     // considerable effort for cleaning up the the remembered sets. This is
4279     // required because stale remembered sets might reference locations that
4280     // are currently allocated into.
4281     uint region_idx = r->hrm_index();
4282     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4283         !r->rem_set()->is_empty()) {
4284       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",
4285                                region_idx,
4286                                (size_t)obj->size() * HeapWordSize,
4287                                p2i(r->bottom()),
4288                                r->rem_set()->occupied(),
4289                                r->rem_set()->strong_code_roots_list_length(),
4290                                next_bitmap->is_marked(r->bottom()),
4291                                g1h->is_humongous_reclaim_candidate(region_idx),
4292                                obj->is_typeArray()
4293                               );
4294       return false;
4295     }
4296 
4297     guarantee(obj->is_typeArray(),
4298               "Only eagerly reclaiming type arrays is supported, but the object "
4299               PTR_FORMAT " is not.", p2i(r->bottom()));
4300 
4301     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",
4302                              region_idx,
4303                              (size_t)obj->size() * HeapWordSize,
4304                              p2i(r->bottom()),
4305                              r->rem_set()->occupied(),
4306                              r->rem_set()->strong_code_roots_list_length(),
4307                              next_bitmap->is_marked(r->bottom()),
4308                              g1h->is_humongous_reclaim_candidate(region_idx),
4309                              obj->is_typeArray()
4310                             );
4311 
4312     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4313     cm->humongous_object_eagerly_reclaimed(r);
4314     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4315            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4316            region_idx,
4317            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4318            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4319     _humongous_objects_reclaimed++;
4320     do {
4321       HeapRegion* next = g1h->next_region_in_humongous(r);
4322       _freed_bytes += r->used();
4323       r->set_containing_set(NULL);
4324       _humongous_regions_reclaimed++;
4325       g1h->free_humongous_region(r, _free_region_list);
4326       r = next;
4327     } while (r != NULL);
4328 
4329     return false;
4330   }
4331 
4332   uint humongous_objects_reclaimed() {
4333     return _humongous_objects_reclaimed;
4334   }
4335 
4336   uint humongous_regions_reclaimed() {
4337     return _humongous_regions_reclaimed;
4338   }
4339 
4340   size_t bytes_freed() const {
4341     return _freed_bytes;
4342   }
4343 };
4344 
4345 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4346   assert_at_safepoint_on_vm_thread();
4347 
4348   if (!G1EagerReclaimHumongousObjects ||
4349       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4350     phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4351     return;
4352   }
4353 
4354   double start_time = os::elapsedTime();
4355 
4356   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4357 
4358   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4359   heap_region_iterate(&cl);
4360 
4361   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4362 
4363   G1HRPrinter* hrp = hr_printer();
4364   if (hrp->is_active()) {
4365     FreeRegionListIterator iter(&local_cleanup_list);
4366     while (iter.more_available()) {
4367       HeapRegion* hr = iter.get_next();
4368       hrp->cleanup(hr);
4369     }
4370   }
4371 
4372   prepend_to_freelist(&local_cleanup_list);
4373   decrement_summary_bytes(cl.bytes_freed());
4374 
4375   phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4376                                                        cl.humongous_objects_reclaimed());
4377 }
4378 
4379 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4380 public:
4381   virtual bool do_heap_region(HeapRegion* r) {
4382     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4383     G1CollectedHeap::heap()->clear_region_attr(r);
4384     r->clear_young_index_in_cset();
4385     return false;
4386   }
4387 };
4388 
4389 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4390   G1AbandonCollectionSetClosure cl;
4391   collection_set_iterate_all(&cl);
4392 
4393   collection_set->clear();
4394   collection_set->stop_incremental_building();
4395 }
4396 
4397 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4398   return _allocator->is_retained_old_region(hr);
4399 }
4400 
4401 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4402   _eden.add(hr);
4403   _policy->set_region_eden(hr);
4404 }
4405 
4406 #ifdef ASSERT
4407 
4408 class NoYoungRegionsClosure: public HeapRegionClosure {
4409 private:
4410   bool _success;
4411 public:
4412   NoYoungRegionsClosure() : _success(true) { }
4413   bool do_heap_region(HeapRegion* r) {
4414     if (r->is_young()) {
4415       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4416                             p2i(r->bottom()), p2i(r->end()));
4417       _success = false;
4418     }
4419     return false;
4420   }
4421   bool success() { return _success; }
4422 };
4423 
4424 bool G1CollectedHeap::check_young_list_empty() {
4425   bool ret = (young_regions_count() == 0);
4426 
4427   NoYoungRegionsClosure closure;
4428   heap_region_iterate(&closure);
4429   ret = ret && closure.success();
4430 
4431   return ret;
4432 }
4433 
4434 #endif // ASSERT
4435 
4436 class TearDownRegionSetsClosure : public HeapRegionClosure {
4437   HeapRegionSet *_old_set;
4438 
4439 public:
4440   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4441 
4442   bool do_heap_region(HeapRegion* r) {
4443     if (r->is_old()) {
4444       _old_set->remove(r);
4445     } else if(r->is_young()) {
4446       r->uninstall_surv_rate_group();
4447     } else {
4448       // We ignore free regions, we'll empty the free list afterwards.
4449       // We ignore humongous and archive regions, we're not tearing down these
4450       // sets.
4451       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4452              "it cannot be another type");
4453     }
4454     return false;
4455   }
4456 
4457   ~TearDownRegionSetsClosure() {
4458     assert(_old_set->is_empty(), "post-condition");
4459   }
4460 };
4461 
4462 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4463   assert_at_safepoint_on_vm_thread();
4464 
4465   if (!free_list_only) {
4466     TearDownRegionSetsClosure cl(&_old_set);
4467     heap_region_iterate(&cl);
4468 
4469     // Note that emptying the _young_list is postponed and instead done as
4470     // the first step when rebuilding the regions sets again. The reason for
4471     // this is that during a full GC string deduplication needs to know if
4472     // a collected region was young or old when the full GC was initiated.
4473   }
4474   _hrm->remove_all_free_regions();
4475 }
4476 
4477 void G1CollectedHeap::increase_used(size_t bytes) {
4478   _summary_bytes_used += bytes;
4479 }
4480 
4481 void G1CollectedHeap::decrease_used(size_t bytes) {
4482   assert(_summary_bytes_used >= bytes,
4483          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4484          _summary_bytes_used, bytes);
4485   _summary_bytes_used -= bytes;
4486 }
4487 
4488 void G1CollectedHeap::set_used(size_t bytes) {
4489   _summary_bytes_used = bytes;
4490 }
4491 
4492 class RebuildRegionSetsClosure : public HeapRegionClosure {
4493 private:
4494   bool _free_list_only;
4495 
4496   HeapRegionSet* _old_set;
4497   HeapRegionManager* _hrm;
4498 
4499   size_t _total_used;
4500 
4501 public:
4502   RebuildRegionSetsClosure(bool free_list_only,
4503                            HeapRegionSet* old_set,
4504                            HeapRegionManager* hrm) :
4505     _free_list_only(free_list_only),
4506     _old_set(old_set), _hrm(hrm), _total_used(0) {
4507     assert(_hrm->num_free_regions() == 0, "pre-condition");
4508     if (!free_list_only) {
4509       assert(_old_set->is_empty(), "pre-condition");
4510     }
4511   }
4512 
4513   bool do_heap_region(HeapRegion* r) {
4514     if (r->is_empty()) {
4515       assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4516       // Add free regions to the free list
4517       r->set_free();
4518       _hrm->insert_into_free_list(r);
4519     } else if (!_free_list_only) {
4520       assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4521 
4522       if (r->is_archive() || r->is_humongous()) {
4523         // We ignore archive and humongous regions. We left these sets unchanged.
4524       } else {
4525         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4526         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4527         r->move_to_old();
4528         _old_set->add(r);
4529       }
4530       _total_used += r->used();
4531     }
4532 
4533     return false;
4534   }
4535 
4536   size_t total_used() {
4537     return _total_used;
4538   }
4539 };
4540 
4541 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4542   assert_at_safepoint_on_vm_thread();
4543 
4544   if (!free_list_only) {
4545     _eden.clear();
4546     _survivor.clear();
4547   }
4548 
4549   RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4550   heap_region_iterate(&cl);
4551 
4552   if (!free_list_only) {
4553     set_used(cl.total_used());
4554     if (_archive_allocator != NULL) {
4555       _archive_allocator->clear_used();
4556     }
4557   }
4558   assert_used_and_recalculate_used_equal(this);
4559 }
4560 
4561 // Methods for the mutator alloc region
4562 
4563 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4564                                                       bool force) {
4565   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4566   bool should_allocate = policy()->should_allocate_mutator_region();
4567   if (force || should_allocate) {
4568     HeapRegion* new_alloc_region = new_region(word_size,
4569                                               HeapRegionType::Eden,
4570                                               false /* do_expand */);
4571     if (new_alloc_region != NULL) {
4572       set_region_short_lived_locked(new_alloc_region);
4573       _hr_printer.alloc(new_alloc_region, !should_allocate);
4574       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4575       _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4576       return new_alloc_region;
4577     }
4578   }
4579   return NULL;
4580 }
4581 
4582 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4583                                                   size_t allocated_bytes) {
4584   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4585   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4586 
4587   collection_set()->add_eden_region(alloc_region);
4588   increase_used(allocated_bytes);
4589   _eden.add_used_bytes(allocated_bytes);
4590   _hr_printer.retire(alloc_region);
4591 
4592   // We update the eden sizes here, when the region is retired,
4593   // instead of when it's allocated, since this is the point that its
4594   // used space has been recorded in _summary_bytes_used.
4595   g1mm()->update_eden_size();
4596 }
4597 
4598 // Methods for the GC alloc regions
4599 
4600 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4601   if (dest.is_old()) {
4602     return true;
4603   } else {
4604     return survivor_regions_count() < policy()->max_survivor_regions();
4605   }
4606 }
4607 
4608 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest) {
4609   assert(FreeList_lock->owned_by_self(), "pre-condition");
4610 
4611   if (!has_more_regions(dest)) {
4612     return NULL;
4613   }
4614 
4615   HeapRegionType type;
4616   if (dest.is_young()) {
4617     type = HeapRegionType::Survivor;
4618   } else {
4619     type = HeapRegionType::Old;
4620   }
4621 
4622   HeapRegion* new_alloc_region = new_region(word_size,
4623                                             type,
4624                                             true /* do_expand */);
4625 
4626   if (new_alloc_region != NULL) {
4627     if (type.is_survivor()) {
4628       new_alloc_region->set_survivor();
4629       _survivor.add(new_alloc_region);
4630       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4631     } else {
4632       new_alloc_region->set_old();
4633       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4634     }
4635     _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4636     register_region_with_region_attr(new_alloc_region);
4637     _hr_printer.alloc(new_alloc_region);
4638     return new_alloc_region;
4639   }
4640   return NULL;
4641 }
4642 
4643 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4644                                              size_t allocated_bytes,
4645                                              G1HeapRegionAttr dest) {
4646   policy()->record_bytes_copied_during_gc(allocated_bytes);
4647   if (dest.is_old()) {
4648     old_set_add(alloc_region);
4649   } else {
4650     assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4651     _survivor.add_used_bytes(allocated_bytes);
4652   }
4653 
4654   bool const during_im = collector_state()->in_initial_mark_gc();
4655   if (during_im && allocated_bytes > 0) {
4656     _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4657   }
4658   _hr_printer.retire(alloc_region);
4659 }
4660 
4661 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4662   bool expanded = false;
4663   uint index = _hrm->find_highest_free(&expanded);
4664 
4665   if (index != G1_NO_HRM_INDEX) {
4666     if (expanded) {
4667       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4668                                 HeapRegion::GrainWords * HeapWordSize);
4669     }
4670     _hrm->allocate_free_regions_starting_at(index, 1);
4671     return region_at(index);
4672   }
4673   return NULL;
4674 }
4675 
4676 // Optimized nmethod scanning
4677 
4678 class RegisterNMethodOopClosure: public OopClosure {
4679   G1CollectedHeap* _g1h;
4680   nmethod* _nm;
4681 
4682   template <class T> void do_oop_work(T* p) {
4683     T heap_oop = RawAccess<>::oop_load(p);
4684     if (!CompressedOops::is_null(heap_oop)) {
4685       oop obj = CompressedOops::decode_not_null(heap_oop);
4686       HeapRegion* hr = _g1h->heap_region_containing(obj);
4687       assert(!hr->is_continues_humongous(),
4688              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4689              " starting at " HR_FORMAT,
4690              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4691 
4692       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4693       hr->add_strong_code_root_locked(_nm);
4694     }
4695   }
4696 
4697 public:
4698   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4699     _g1h(g1h), _nm(nm) {}
4700 
4701   void do_oop(oop* p)       { do_oop_work(p); }
4702   void do_oop(narrowOop* p) { do_oop_work(p); }
4703 };
4704 
4705 class UnregisterNMethodOopClosure: public OopClosure {
4706   G1CollectedHeap* _g1h;
4707   nmethod* _nm;
4708 
4709   template <class T> void do_oop_work(T* p) {
4710     T heap_oop = RawAccess<>::oop_load(p);
4711     if (!CompressedOops::is_null(heap_oop)) {
4712       oop obj = CompressedOops::decode_not_null(heap_oop);
4713       HeapRegion* hr = _g1h->heap_region_containing(obj);
4714       assert(!hr->is_continues_humongous(),
4715              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4716              " starting at " HR_FORMAT,
4717              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4718 
4719       hr->remove_strong_code_root(_nm);
4720     }
4721   }
4722 
4723 public:
4724   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4725     _g1h(g1h), _nm(nm) {}
4726 
4727   void do_oop(oop* p)       { do_oop_work(p); }
4728   void do_oop(narrowOop* p) { do_oop_work(p); }
4729 };
4730 
4731 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4732   guarantee(nm != NULL, "sanity");
4733   RegisterNMethodOopClosure reg_cl(this, nm);
4734   nm->oops_do(&reg_cl);
4735 }
4736 
4737 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4738   guarantee(nm != NULL, "sanity");
4739   UnregisterNMethodOopClosure reg_cl(this, nm);
4740   nm->oops_do(&reg_cl, true);
4741 }
4742 
4743 void G1CollectedHeap::purge_code_root_memory() {
4744   double purge_start = os::elapsedTime();
4745   G1CodeRootSet::purge();
4746   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4747   phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4748 }
4749 
4750 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4751   G1CollectedHeap* _g1h;
4752 
4753 public:
4754   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4755     _g1h(g1h) {}
4756 
4757   void do_code_blob(CodeBlob* cb) {
4758     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4759     if (nm == NULL) {
4760       return;
4761     }
4762 
4763     _g1h->register_nmethod(nm);
4764   }
4765 };
4766 
4767 void G1CollectedHeap::rebuild_strong_code_roots() {
4768   RebuildStrongCodeRootClosure blob_cl(this);
4769   CodeCache::blobs_do(&blob_cl);
4770 }
4771 
4772 void G1CollectedHeap::initialize_serviceability() {
4773   _g1mm->initialize_serviceability();
4774 }
4775 
4776 MemoryUsage G1CollectedHeap::memory_usage() {
4777   return _g1mm->memory_usage();
4778 }
4779 
4780 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4781   return _g1mm->memory_managers();
4782 }
4783 
4784 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4785   return _g1mm->memory_pools();
4786 }