rev 60421 : [mq]: 8248401-stefank-review

   1 /*
   2  * Copyright (c) 2001, 2020, 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/g1GCParPhaseTimesTracker.hpp"
  45 #include "gc/g1/g1GCPhaseTimes.hpp"
  46 #include "gc/g1/g1HeapSizingPolicy.hpp"
  47 #include "gc/g1/g1HeapTransition.hpp"
  48 #include "gc/g1/g1HeapVerifier.hpp"
  49 #include "gc/g1/g1HotCardCache.hpp"
  50 #include "gc/g1/g1InitLogger.hpp"
  51 #include "gc/g1/g1MemoryPool.hpp"
  52 #include "gc/g1/g1OopClosures.inline.hpp"
  53 #include "gc/g1/g1ParallelCleaning.hpp"
  54 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  55 #include "gc/g1/g1Policy.hpp"
  56 #include "gc/g1/g1RedirtyCardsQueue.hpp"
  57 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  58 #include "gc/g1/g1RemSet.hpp"
  59 #include "gc/g1/g1RootClosures.hpp"
  60 #include "gc/g1/g1RootProcessor.hpp"
  61 #include "gc/g1/g1SATBMarkQueueSet.hpp"
  62 #include "gc/g1/g1StringDedup.hpp"
  63 #include "gc/g1/g1ThreadLocalData.hpp"
  64 #include "gc/g1/g1Trace.hpp"
  65 #include "gc/g1/g1YCTypes.hpp"
  66 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  67 #include "gc/g1/g1VMOperations.hpp"
  68 #include "gc/g1/heapRegion.inline.hpp"
  69 #include "gc/g1/heapRegionRemSet.hpp"
  70 #include "gc/g1/heapRegionSet.inline.hpp"
  71 #include "gc/shared/concurrentGCBreakpoints.hpp"
  72 #include "gc/shared/gcBehaviours.hpp"
  73 #include "gc/shared/gcHeapSummary.hpp"
  74 #include "gc/shared/gcId.hpp"
  75 #include "gc/shared/gcLocker.hpp"
  76 #include "gc/shared/gcTimer.hpp"
  77 #include "gc/shared/gcTraceTime.inline.hpp"
  78 #include "gc/shared/generationSpec.hpp"
  79 #include "gc/shared/isGCActiveMark.hpp"
  80 #include "gc/shared/locationPrinter.inline.hpp"
  81 #include "gc/shared/oopStorageParState.hpp"
  82 #include "gc/shared/preservedMarks.inline.hpp"
  83 #include "gc/shared/suspendibleThreadSet.hpp"
  84 #include "gc/shared/referenceProcessor.inline.hpp"
  85 #include "gc/shared/taskTerminator.hpp"
  86 #include "gc/shared/taskqueue.inline.hpp"
  87 #include "gc/shared/weakProcessor.inline.hpp"
  88 #include "gc/shared/workerPolicy.hpp"
  89 #include "logging/log.hpp"
  90 #include "memory/allocation.hpp"
  91 #include "memory/iterator.hpp"
  92 #include "memory/resourceArea.hpp"
  93 #include "memory/universe.hpp"
  94 #include "oops/access.inline.hpp"
  95 #include "oops/compressedOops.inline.hpp"
  96 #include "oops/oop.inline.hpp"
  97 #include "runtime/atomic.hpp"
  98 #include "runtime/handles.inline.hpp"
  99 #include "runtime/init.hpp"
 100 #include "runtime/orderAccess.hpp"
 101 #include "runtime/threadSMR.hpp"
 102 #include "runtime/vmThread.hpp"
 103 #include "utilities/align.hpp"
 104 #include "utilities/autoRestore.hpp"
 105 #include "utilities/bitMap.inline.hpp"
 106 #include "utilities/globalDefinitions.hpp"
 107 #include "utilities/stack.inline.hpp"
 108 
 109 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
 110 
 111 // INVARIANTS/NOTES
 112 //
 113 // All allocation activity covered by the G1CollectedHeap interface is
 114 // serialized by acquiring the HeapLock.  This happens in mem_allocate
 115 // and allocate_new_tlab, which are the "entry" points to the
 116 // allocation code from the rest of the JVM.  (Note that this does not
 117 // apply to TLAB allocation, which is not part of this interface: it
 118 // is done by clients of this interface.)
 119 
 120 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
 121  private:
 122   size_t _num_dirtied;
 123   G1CollectedHeap* _g1h;
 124   G1CardTable* _g1_ct;
 125 
 126   HeapRegion* region_for_card(CardValue* card_ptr) const {
 127     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
 128   }
 129 
 130   bool will_become_free(HeapRegion* hr) const {
 131     // A region will be freed by free_collection_set if the region is in the
 132     // collection set and has not had an evacuation failure.
 133     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 134   }
 135 
 136  public:
 137   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
 138     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
 139 
 140   void do_card_ptr(CardValue* card_ptr, uint worker_id) {
 141     HeapRegion* hr = region_for_card(card_ptr);
 142 
 143     // Should only dirty cards in regions that won't be freed.
 144     if (!will_become_free(hr)) {
 145       *card_ptr = G1CardTable::dirty_card_val();
 146       _num_dirtied++;
 147     }
 148   }
 149 
 150   size_t num_dirtied()   const { return _num_dirtied; }
 151 };
 152 
 153 
 154 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 155   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 156 }
 157 
 158 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 159   // The from card cache is not the memory that is actually committed. So we cannot
 160   // take advantage of the zero_filled parameter.
 161   reset_from_card_cache(start_idx, num_regions);
 162 }
 163 
 164 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
 165   Ticks start = Ticks::now();
 166   workers()->run_task(task, workers()->active_workers());
 167   return Ticks::now() - start;
 168 }
 169 
 170 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 171                                              MemRegion mr) {
 172   return new HeapRegion(hrs_index, bot(), mr);
 173 }
 174 
 175 // Private methods.
 176 
 177 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
 178                                         HeapRegionType type,
 179                                         bool do_expand,
 180                                         uint node_index) {
 181   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 182          "the only time we use this to allocate a humongous region is "
 183          "when we are allocating a single humongous region");
 184 
 185   HeapRegion* res = _hrm->allocate_free_region(type, node_index);
 186 
 187   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 188     // Currently, only attempts to allocate GC alloc regions set
 189     // do_expand to true. So, we should only reach here during a
 190     // safepoint. If this assumption changes we might have to
 191     // reconsider the use of _expand_heap_after_alloc_failure.
 192     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 193 
 194     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 195                               word_size * HeapWordSize);
 196 
 197     assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
 198            "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
 199            word_size * HeapWordSize);
 200     if (expand_single_region(node_index)) {
 201       // Given that expand_single_region() succeeded in expanding the heap, and we
 202       // always expand the heap by an amount aligned to the heap
 203       // region size, the free list should in theory not be empty.
 204       // In either case allocate_free_region() will check for NULL.
 205       res = _hrm->allocate_free_region(type, node_index);
 206     } else {
 207       _expand_heap_after_alloc_failure = false;
 208     }
 209   }
 210   return res;
 211 }
 212 
 213 HeapWord*
 214 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
 215                                                            uint num_regions,
 216                                                            size_t word_size) {
 217   assert(first_hr != NULL, "pre-condition");
 218   assert(is_humongous(word_size), "word_size should be humongous");
 219   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 220 
 221   // Index of last region in the series.
 222   uint first = first_hr->hrm_index();
 223   uint last = first + num_regions - 1;
 224 
 225   // We need to initialize the region(s) we just discovered. This is
 226   // a bit tricky given that it can happen concurrently with
 227   // refinement threads refining cards on these regions and
 228   // potentially wanting to refine the BOT as they are scanning
 229   // those cards (this can happen shortly after a cleanup; see CR
 230   // 6991377). So we have to set up the region(s) carefully and in
 231   // a specific order.
 232 
 233   // The word size sum of all the regions we will allocate.
 234   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 235   assert(word_size <= word_size_sum, "sanity");
 236 
 237   // The passed in hr will be the "starts humongous" region. The header
 238   // of the new object will be placed at the bottom of this region.
 239   HeapWord* new_obj = first_hr->bottom();
 240   // This will be the new top of the new object.
 241   HeapWord* obj_top = new_obj + word_size;
 242 
 243   // First, we need to zero the header of the space that we will be
 244   // allocating. When we update top further down, some refinement
 245   // threads might try to scan the region. By zeroing the header we
 246   // ensure that any thread that will try to scan the region will
 247   // come across the zero klass word and bail out.
 248   //
 249   // NOTE: It would not have been correct to have used
 250   // CollectedHeap::fill_with_object() and make the space look like
 251   // an int array. The thread that is doing the allocation will
 252   // later update the object header to a potentially different array
 253   // type and, for a very short period of time, the klass and length
 254   // fields will be inconsistent. This could cause a refinement
 255   // thread to calculate the object size incorrectly.
 256   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 257 
 258   // Next, pad out the unused tail of the last region with filler
 259   // objects, for improved usage accounting.
 260   // How many words we use for filler objects.
 261   size_t word_fill_size = word_size_sum - word_size;
 262 
 263   // How many words memory we "waste" which cannot hold a filler object.
 264   size_t words_not_fillable = 0;
 265 
 266   if (word_fill_size >= min_fill_size()) {
 267     fill_with_objects(obj_top, word_fill_size);
 268   } else if (word_fill_size > 0) {
 269     // We have space to fill, but we cannot fit an object there.
 270     words_not_fillable = word_fill_size;
 271     word_fill_size = 0;
 272   }
 273 
 274   // We will set up the first region as "starts humongous". This
 275   // will also update the BOT covering all the regions to reflect
 276   // that there is a single object that starts at the bottom of the
 277   // first region.
 278   first_hr->set_starts_humongous(obj_top, word_fill_size);
 279   _policy->remset_tracker()->update_at_allocate(first_hr);
 280   // Then, if there are any, we will set up the "continues
 281   // humongous" regions.
 282   HeapRegion* hr = NULL;
 283   for (uint i = first + 1; i <= last; ++i) {
 284     hr = region_at(i);
 285     hr->set_continues_humongous(first_hr);
 286     _policy->remset_tracker()->update_at_allocate(hr);
 287   }
 288 
 289   // Up to this point no concurrent thread would have been able to
 290   // do any scanning on any region in this series. All the top
 291   // fields still point to bottom, so the intersection between
 292   // [bottom,top] and [card_start,card_end] will be empty. Before we
 293   // update the top fields, we'll do a storestore to make sure that
 294   // no thread sees the update to top before the zeroing of the
 295   // object header and the BOT initialization.
 296   OrderAccess::storestore();
 297 
 298   // Now, we will update the top fields of the "continues humongous"
 299   // regions except the last one.
 300   for (uint i = first; i < last; ++i) {
 301     hr = region_at(i);
 302     hr->set_top(hr->end());
 303   }
 304 
 305   hr = region_at(last);
 306   // If we cannot fit a filler object, we must set top to the end
 307   // of the humongous object, otherwise we cannot iterate the heap
 308   // and the BOT will not be complete.
 309   hr->set_top(hr->end() - words_not_fillable);
 310 
 311   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 312          "obj_top should be in last region");
 313 
 314   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 315 
 316   assert(words_not_fillable == 0 ||
 317          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 318          "Miscalculation in humongous allocation");
 319 
 320   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 321 
 322   for (uint i = first; i <= last; ++i) {
 323     hr = region_at(i);
 324     _humongous_set.add(hr);
 325     _hr_printer.alloc(hr);
 326   }
 327 
 328   return new_obj;
 329 }
 330 
 331 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 332   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 333   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 334 }
 335 
 336 // If could fit into free regions w/o expansion, try.
 337 // Otherwise, if can expand, do so.
 338 // Otherwise, if using ex regions might help, try with ex given back.
 339 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 340   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 341 
 342   _verifier->verify_region_sets_optional();
 343 
 344   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 345 
 346   // Policy: First try to allocate a humongous object in the free list.
 347   HeapRegion* humongous_start = _hrm->allocate_humongous(obj_regions);
 348   if (humongous_start == NULL) {
 349     // Policy: We could not find enough regions for the humongous object in the
 350     // free list. Look through the heap to find a mix of free and uncommitted regions.
 351     // If so, expand the heap and allocate the humongous object.
 352     humongous_start = _hrm->expand_and_allocate_humongous(obj_regions);
 353     if (humongous_start != NULL) {
 354       // We managed to find a region by expanding the heap.
 355       log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
 356                                 word_size * HeapWordSize);
 357       policy()->record_new_heap_size(num_regions());
 358     } else {
 359       // Policy: Potentially trigger a defragmentation GC.
 360     }
 361   }
 362 
 363   HeapWord* result = NULL;
 364   if (humongous_start != NULL) {
 365     result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
 366     assert(result != NULL, "it should always return a valid result");
 367 
 368     // A successful humongous object allocation changes the used space
 369     // information of the old generation so we need to recalculate the
 370     // sizes and update the jstat counters here.
 371     g1mm()->update_sizes();
 372   }
 373 
 374   _verifier->verify_region_sets_optional();
 375 
 376   return result;
 377 }
 378 
 379 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
 380                                              size_t requested_size,
 381                                              size_t* actual_size) {
 382   assert_heap_not_locked_and_not_at_safepoint();
 383   assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
 384 
 385   return attempt_allocation(min_size, requested_size, actual_size);
 386 }
 387 
 388 HeapWord*
 389 G1CollectedHeap::mem_allocate(size_t word_size,
 390                               bool*  gc_overhead_limit_was_exceeded) {
 391   assert_heap_not_locked_and_not_at_safepoint();
 392 
 393   if (is_humongous(word_size)) {
 394     return attempt_allocation_humongous(word_size);
 395   }
 396   size_t dummy = 0;
 397   return attempt_allocation(word_size, word_size, &dummy);
 398 }
 399 
 400 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 401   ResourceMark rm; // For retrieving the thread names in log messages.
 402 
 403   // Make sure you read the note in attempt_allocation_humongous().
 404 
 405   assert_heap_not_locked_and_not_at_safepoint();
 406   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 407          "be called for humongous allocation requests");
 408 
 409   // We should only get here after the first-level allocation attempt
 410   // (attempt_allocation()) failed to allocate.
 411 
 412   // We will loop until a) we manage to successfully perform the
 413   // allocation or b) we successfully schedule a collection which
 414   // fails to perform the allocation. b) is the only case when we'll
 415   // return NULL.
 416   HeapWord* result = NULL;
 417   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 418     bool should_try_gc;
 419     uint gc_count_before;
 420 
 421     {
 422       MutexLocker x(Heap_lock);
 423       result = _allocator->attempt_allocation_locked(word_size);
 424       if (result != NULL) {
 425         return result;
 426       }
 427 
 428       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 429       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 430       // waiting because the GCLocker is active to not wait too long.
 431       if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
 432         // No need for an ergo message here, can_expand_young_list() does this when
 433         // it returns true.
 434         result = _allocator->attempt_allocation_force(word_size);
 435         if (result != NULL) {
 436           return result;
 437         }
 438       }
 439       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 440       // the GCLocker initiated GC has been performed and then retry. This includes
 441       // the case when the GC Locker is not active but has not been performed.
 442       should_try_gc = !GCLocker::needs_gc();
 443       // Read the GC count while still holding the Heap_lock.
 444       gc_count_before = total_collections();
 445     }
 446 
 447     if (should_try_gc) {
 448       bool succeeded;
 449       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 450                                    GCCause::_g1_inc_collection_pause);
 451       if (result != NULL) {
 452         assert(succeeded, "only way to get back a non-NULL result");
 453         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 454                              Thread::current()->name(), p2i(result));
 455         return result;
 456       }
 457 
 458       if (succeeded) {
 459         // We successfully scheduled a collection which failed to allocate. No
 460         // point in trying to allocate further. We'll just return NULL.
 461         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 462                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 463         return NULL;
 464       }
 465       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 466                            Thread::current()->name(), word_size);
 467     } else {
 468       // Failed to schedule a collection.
 469       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 470         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 471                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 472         return NULL;
 473       }
 474       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 475       // The GCLocker is either active or the GCLocker initiated
 476       // GC has not yet been performed. Stall until it is and
 477       // then retry the allocation.
 478       GCLocker::stall_until_clear();
 479       gclocker_retry_count += 1;
 480     }
 481 
 482     // We can reach here if we were unsuccessful in scheduling a
 483     // collection (because another thread beat us to it) or if we were
 484     // stalled due to the GC locker. In either can we should retry the
 485     // allocation attempt in case another thread successfully
 486     // performed a collection and reclaimed enough space. We do the
 487     // first attempt (without holding the Heap_lock) here and the
 488     // follow-on attempt will be at the start of the next loop
 489     // iteration (after taking the Heap_lock).
 490     size_t dummy = 0;
 491     result = _allocator->attempt_allocation(word_size, word_size, &dummy);
 492     if (result != NULL) {
 493       return result;
 494     }
 495 
 496     // Give a warning if we seem to be looping forever.
 497     if ((QueuedAllocationWarningCount > 0) &&
 498         (try_count % QueuedAllocationWarningCount == 0)) {
 499       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 500                              Thread::current()->name(), try_count, word_size);
 501     }
 502   }
 503 
 504   ShouldNotReachHere();
 505   return NULL;
 506 }
 507 
 508 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 509   assert_at_safepoint_on_vm_thread();
 510   if (_archive_allocator == NULL) {
 511     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 512   }
 513 }
 514 
 515 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 516   // Allocations in archive regions cannot be of a size that would be considered
 517   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 518   // may be different at archive-restore time.
 519   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 520 }
 521 
 522 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 523   assert_at_safepoint_on_vm_thread();
 524   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 525   if (is_archive_alloc_too_large(word_size)) {
 526     return NULL;
 527   }
 528   return _archive_allocator->archive_mem_allocate(word_size);
 529 }
 530 
 531 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 532                                               size_t end_alignment_in_bytes) {
 533   assert_at_safepoint_on_vm_thread();
 534   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 535 
 536   // Call complete_archive to do the real work, filling in the MemRegion
 537   // array with the archive regions.
 538   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 539   delete _archive_allocator;
 540   _archive_allocator = NULL;
 541 }
 542 
 543 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 544   assert(ranges != NULL, "MemRegion array NULL");
 545   assert(count != 0, "No MemRegions provided");
 546   MemRegion reserved = _hrm->reserved();
 547   for (size_t i = 0; i < count; i++) {
 548     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 549       return false;
 550     }
 551   }
 552   return true;
 553 }
 554 
 555 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 556                                             size_t count,
 557                                             bool open) {
 558   assert(!is_init_completed(), "Expect to be called at JVM init time");
 559   assert(ranges != NULL, "MemRegion array NULL");
 560   assert(count != 0, "No MemRegions provided");
 561   MutexLocker x(Heap_lock);
 562 
 563   MemRegion reserved = _hrm->reserved();
 564   HeapWord* prev_last_addr = NULL;
 565   HeapRegion* prev_last_region = NULL;
 566 
 567   // Temporarily disable pretouching of heap pages. This interface is used
 568   // when mmap'ing archived heap data in, so pre-touching is wasted.
 569   FlagSetting fs(AlwaysPreTouch, false);
 570 
 571   // Enable archive object checking used by G1MarkSweep. We have to let it know
 572   // about each archive range, so that objects in those ranges aren't marked.
 573   G1ArchiveAllocator::enable_archive_object_check();
 574 
 575   // For each specified MemRegion range, allocate the corresponding G1
 576   // regions and mark them as archive regions. We expect the ranges
 577   // in ascending starting address order, without overlap.
 578   for (size_t i = 0; i < count; i++) {
 579     MemRegion curr_range = ranges[i];
 580     HeapWord* start_address = curr_range.start();
 581     size_t word_size = curr_range.word_size();
 582     HeapWord* last_address = curr_range.last();
 583     size_t commits = 0;
 584 
 585     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 586               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 587               p2i(start_address), p2i(last_address));
 588     guarantee(start_address > prev_last_addr,
 589               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 590               p2i(start_address), p2i(prev_last_addr));
 591     prev_last_addr = last_address;
 592 
 593     // Check for ranges that start in the same G1 region in which the previous
 594     // range ended, and adjust the start address so we don't try to allocate
 595     // the same region again. If the current range is entirely within that
 596     // region, skip it, just adjusting the recorded top.
 597     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 598     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 599       start_address = start_region->end();
 600       if (start_address > last_address) {
 601         increase_used(word_size * HeapWordSize);
 602         start_region->set_top(last_address + 1);
 603         continue;
 604       }
 605       start_region->set_top(start_address);
 606       curr_range = MemRegion(start_address, last_address + 1);
 607       start_region = _hrm->addr_to_region(start_address);
 608     }
 609 
 610     // Perform the actual region allocation, exiting if it fails.
 611     // Then note how much new space we have allocated.
 612     if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
 613       return false;
 614     }
 615     increase_used(word_size * HeapWordSize);
 616     if (commits != 0) {
 617       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 618                                 HeapRegion::GrainWords * HeapWordSize * commits);
 619 
 620     }
 621 
 622     // Mark each G1 region touched by the range as archive, add it to
 623     // the old set, and set top.
 624     HeapRegion* curr_region = _hrm->addr_to_region(start_address);
 625     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 626     prev_last_region = last_region;
 627 
 628     while (curr_region != NULL) {
 629       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 630              "Region already in use (index %u)", curr_region->hrm_index());
 631       if (open) {
 632         curr_region->set_open_archive();
 633       } else {
 634         curr_region->set_closed_archive();
 635       }
 636       _hr_printer.alloc(curr_region);
 637       _archive_set.add(curr_region);
 638       HeapWord* top;
 639       HeapRegion* next_region;
 640       if (curr_region != last_region) {
 641         top = curr_region->end();
 642         next_region = _hrm->next_region_in_heap(curr_region);
 643       } else {
 644         top = last_address + 1;
 645         next_region = NULL;
 646       }
 647       curr_region->set_top(top);
 648       curr_region = next_region;
 649     }
 650 
 651     // Notify mark-sweep of the archive
 652     G1ArchiveAllocator::set_range_archive(curr_range, open);
 653   }
 654   return true;
 655 }
 656 
 657 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 658   assert(!is_init_completed(), "Expect to be called at JVM init time");
 659   assert(ranges != NULL, "MemRegion array NULL");
 660   assert(count != 0, "No MemRegions provided");
 661   MemRegion reserved = _hrm->reserved();
 662   HeapWord *prev_last_addr = NULL;
 663   HeapRegion* prev_last_region = NULL;
 664 
 665   // For each MemRegion, create filler objects, if needed, in the G1 regions
 666   // that contain the address range. The address range actually within the
 667   // MemRegion will not be modified. That is assumed to have been initialized
 668   // elsewhere, probably via an mmap of archived heap data.
 669   MutexLocker x(Heap_lock);
 670   for (size_t i = 0; i < count; i++) {
 671     HeapWord* start_address = ranges[i].start();
 672     HeapWord* last_address = ranges[i].last();
 673 
 674     assert(reserved.contains(start_address) && reserved.contains(last_address),
 675            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 676            p2i(start_address), p2i(last_address));
 677     assert(start_address > prev_last_addr,
 678            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 679            p2i(start_address), p2i(prev_last_addr));
 680 
 681     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 682     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 683     HeapWord* bottom_address = start_region->bottom();
 684 
 685     // Check for a range beginning in the same region in which the
 686     // previous one ended.
 687     if (start_region == prev_last_region) {
 688       bottom_address = prev_last_addr + 1;
 689     }
 690 
 691     // Verify that the regions were all marked as archive regions by
 692     // alloc_archive_regions.
 693     HeapRegion* curr_region = start_region;
 694     while (curr_region != NULL) {
 695       guarantee(curr_region->is_archive(),
 696                 "Expected archive region at index %u", curr_region->hrm_index());
 697       if (curr_region != last_region) {
 698         curr_region = _hrm->next_region_in_heap(curr_region);
 699       } else {
 700         curr_region = NULL;
 701       }
 702     }
 703 
 704     prev_last_addr = last_address;
 705     prev_last_region = last_region;
 706 
 707     // Fill the memory below the allocated range with dummy object(s),
 708     // if the region bottom does not match the range start, or if the previous
 709     // range ended within the same G1 region, and there is a gap.
 710     if (start_address != bottom_address) {
 711       size_t fill_size = pointer_delta(start_address, bottom_address);
 712       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 713       increase_used(fill_size * HeapWordSize);
 714     }
 715   }
 716 }
 717 
 718 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
 719                                                      size_t desired_word_size,
 720                                                      size_t* actual_word_size) {
 721   assert_heap_not_locked_and_not_at_safepoint();
 722   assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
 723          "be called for humongous allocation requests");
 724 
 725   HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
 726 
 727   if (result == NULL) {
 728     *actual_word_size = desired_word_size;
 729     result = attempt_allocation_slow(desired_word_size);
 730   }
 731 
 732   assert_heap_not_locked();
 733   if (result != NULL) {
 734     assert(*actual_word_size != 0, "Actual size must have been set here");
 735     dirty_young_block(result, *actual_word_size);
 736   } else {
 737     *actual_word_size = 0;
 738   }
 739 
 740   return result;
 741 }
 742 
 743 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 744   assert(!is_init_completed(), "Expect to be called at JVM init time");
 745   assert(ranges != NULL, "MemRegion array NULL");
 746   assert(count != 0, "No MemRegions provided");
 747   MemRegion reserved = _hrm->reserved();
 748   HeapWord* prev_last_addr = NULL;
 749   HeapRegion* prev_last_region = NULL;
 750   size_t size_used = 0;
 751   size_t uncommitted_regions = 0;
 752 
 753   // For each Memregion, free the G1 regions that constitute it, and
 754   // notify mark-sweep that the range is no longer to be considered 'archive.'
 755   MutexLocker x(Heap_lock);
 756   for (size_t i = 0; i < count; i++) {
 757     HeapWord* start_address = ranges[i].start();
 758     HeapWord* last_address = ranges[i].last();
 759 
 760     assert(reserved.contains(start_address) && reserved.contains(last_address),
 761            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 762            p2i(start_address), p2i(last_address));
 763     assert(start_address > prev_last_addr,
 764            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 765            p2i(start_address), p2i(prev_last_addr));
 766     size_used += ranges[i].byte_size();
 767     prev_last_addr = last_address;
 768 
 769     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 770     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 771 
 772     // Check for ranges that start in the same G1 region in which the previous
 773     // range ended, and adjust the start address so we don't try to free
 774     // the same region again. If the current range is entirely within that
 775     // region, skip it.
 776     if (start_region == prev_last_region) {
 777       start_address = start_region->end();
 778       if (start_address > last_address) {
 779         continue;
 780       }
 781       start_region = _hrm->addr_to_region(start_address);
 782     }
 783     prev_last_region = last_region;
 784 
 785     // After verifying that each region was marked as an archive region by
 786     // alloc_archive_regions, set it free and empty and uncommit it.
 787     HeapRegion* curr_region = start_region;
 788     while (curr_region != NULL) {
 789       guarantee(curr_region->is_archive(),
 790                 "Expected archive region at index %u", curr_region->hrm_index());
 791       uint curr_index = curr_region->hrm_index();
 792       _archive_set.remove(curr_region);
 793       curr_region->set_free();
 794       curr_region->set_top(curr_region->bottom());
 795       if (curr_region != last_region) {
 796         curr_region = _hrm->next_region_in_heap(curr_region);
 797       } else {
 798         curr_region = NULL;
 799       }
 800       _hrm->shrink_at(curr_index, 1);
 801       uncommitted_regions++;
 802     }
 803 
 804     // Notify mark-sweep that this is no longer an archive range.
 805     G1ArchiveAllocator::clear_range_archive(ranges[i]);
 806   }
 807 
 808   if (uncommitted_regions != 0) {
 809     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 810                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 811   }
 812   decrease_used(size_used);
 813 }
 814 
 815 oop G1CollectedHeap::materialize_archived_object(oop obj) {
 816   assert(obj != NULL, "archived obj is NULL");
 817   assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
 818 
 819   // Loading an archived object makes it strongly reachable. If it is
 820   // loaded during concurrent marking, it must be enqueued to the SATB
 821   // queue, shading the previously white object gray.
 822   G1BarrierSet::enqueue(obj);
 823 
 824   return obj;
 825 }
 826 
 827 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 828   ResourceMark rm; // For retrieving the thread names in log messages.
 829 
 830   // The structure of this method has a lot of similarities to
 831   // attempt_allocation_slow(). The reason these two were not merged
 832   // into a single one is that such a method would require several "if
 833   // allocation is not humongous do this, otherwise do that"
 834   // conditional paths which would obscure its flow. In fact, an early
 835   // version of this code did use a unified method which was harder to
 836   // follow and, as a result, it had subtle bugs that were hard to
 837   // track down. So keeping these two methods separate allows each to
 838   // be more readable. It will be good to keep these two in sync as
 839   // much as possible.
 840 
 841   assert_heap_not_locked_and_not_at_safepoint();
 842   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 843          "should only be called for humongous allocations");
 844 
 845   // Humongous objects can exhaust the heap quickly, so we should check if we
 846   // need to start a marking cycle at each humongous object allocation. We do
 847   // the check before we do the actual allocation. The reason for doing it
 848   // before the allocation is that we avoid having to keep track of the newly
 849   // allocated memory while we do a GC.
 850   if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
 851                                            word_size)) {
 852     collect(GCCause::_g1_humongous_allocation);
 853   }
 854 
 855   // We will loop until a) we manage to successfully perform the
 856   // allocation or b) we successfully schedule a collection which
 857   // fails to perform the allocation. b) is the only case when we'll
 858   // return NULL.
 859   HeapWord* result = NULL;
 860   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 861     bool should_try_gc;
 862     uint gc_count_before;
 863 
 864 
 865     {
 866       MutexLocker x(Heap_lock);
 867 
 868       // Given that humongous objects are not allocated in young
 869       // regions, we'll first try to do the allocation without doing a
 870       // collection hoping that there's enough space in the heap.
 871       result = humongous_obj_allocate(word_size);
 872       if (result != NULL) {
 873         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 874         policy()->old_gen_alloc_tracker()->
 875           add_allocated_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 876         return result;
 877       }
 878 
 879       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 880       // the GCLocker initiated GC has been performed and then retry. This includes
 881       // the case when the GC Locker is not active but has not been performed.
 882       should_try_gc = !GCLocker::needs_gc();
 883       // Read the GC count while still holding the Heap_lock.
 884       gc_count_before = total_collections();
 885     }
 886 
 887     if (should_try_gc) {
 888       bool succeeded;
 889       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 890                                    GCCause::_g1_humongous_allocation);
 891       if (result != NULL) {
 892         assert(succeeded, "only way to get back a non-NULL result");
 893         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 894                              Thread::current()->name(), p2i(result));
 895         return result;
 896       }
 897 
 898       if (succeeded) {
 899         // We successfully scheduled a collection which failed to allocate. No
 900         // point in trying to allocate further. We'll just return NULL.
 901         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 902                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 903         return NULL;
 904       }
 905       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 906                            Thread::current()->name(), word_size);
 907     } else {
 908       // Failed to schedule a collection.
 909       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 910         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 911                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 912         return NULL;
 913       }
 914       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 915       // The GCLocker is either active or the GCLocker initiated
 916       // GC has not yet been performed. Stall until it is and
 917       // then retry the allocation.
 918       GCLocker::stall_until_clear();
 919       gclocker_retry_count += 1;
 920     }
 921 
 922 
 923     // We can reach here if we were unsuccessful in scheduling a
 924     // collection (because another thread beat us to it) or if we were
 925     // stalled due to the GC locker. In either can we should retry the
 926     // allocation attempt in case another thread successfully
 927     // performed a collection and reclaimed enough space.
 928     // Humongous object allocation always needs a lock, so we wait for the retry
 929     // in the next iteration of the loop, unlike for the regular iteration case.
 930     // Give a warning if we seem to be looping forever.
 931 
 932     if ((QueuedAllocationWarningCount > 0) &&
 933         (try_count % QueuedAllocationWarningCount == 0)) {
 934       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 935                              Thread::current()->name(), try_count, word_size);
 936     }
 937   }
 938 
 939   ShouldNotReachHere();
 940   return NULL;
 941 }
 942 
 943 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 944                                                            bool expect_null_mutator_alloc_region) {
 945   assert_at_safepoint_on_vm_thread();
 946   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 947          "the current alloc region was unexpectedly found to be non-NULL");
 948 
 949   if (!is_humongous(word_size)) {
 950     return _allocator->attempt_allocation_locked(word_size);
 951   } else {
 952     HeapWord* result = humongous_obj_allocate(word_size);
 953     if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
 954       collector_state()->set_initiate_conc_mark_if_possible(true);
 955     }
 956     return result;
 957   }
 958 
 959   ShouldNotReachHere();
 960 }
 961 
 962 class PostCompactionPrinterClosure: public HeapRegionClosure {
 963 private:
 964   G1HRPrinter* _hr_printer;
 965 public:
 966   bool do_heap_region(HeapRegion* hr) {
 967     assert(!hr->is_young(), "not expecting to find young regions");
 968     _hr_printer->post_compaction(hr);
 969     return false;
 970   }
 971 
 972   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 973     : _hr_printer(hr_printer) { }
 974 };
 975 
 976 void G1CollectedHeap::print_hrm_post_compaction() {
 977   if (_hr_printer.is_active()) {
 978     PostCompactionPrinterClosure cl(hr_printer());
 979     heap_region_iterate(&cl);
 980   }
 981 }
 982 
 983 void G1CollectedHeap::abort_concurrent_cycle() {
 984   // If we start the compaction before the CM threads finish
 985   // scanning the root regions we might trip them over as we'll
 986   // be moving objects / updating references. So let's wait until
 987   // they are done. By telling them to abort, they should complete
 988   // early.
 989   _cm->root_regions()->abort();
 990   _cm->root_regions()->wait_until_scan_finished();
 991 
 992   // Disable discovery and empty the discovered lists
 993   // for the CM ref processor.
 994   _ref_processor_cm->disable_discovery();
 995   _ref_processor_cm->abandon_partial_discovery();
 996   _ref_processor_cm->verify_no_references_recorded();
 997 
 998   // Abandon current iterations of concurrent marking and concurrent
 999   // refinement, if any are in progress.
1000   concurrent_mark()->concurrent_cycle_abort();
1001 }
1002 
1003 void G1CollectedHeap::prepare_heap_for_full_collection() {
1004   // Make sure we'll choose a new allocation region afterwards.
1005   _allocator->release_mutator_alloc_regions();
1006   _allocator->abandon_gc_alloc_regions();
1007 
1008   // We may have added regions to the current incremental collection
1009   // set between the last GC or pause and now. We need to clear the
1010   // incremental collection set and then start rebuilding it afresh
1011   // after this full GC.
1012   abandon_collection_set(collection_set());
1013 
1014   tear_down_region_sets(false /* free_list_only */);
1015 
1016   hrm()->prepare_for_full_collection_start();
1017 }
1018 
1019 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1020   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1021   assert_used_and_recalculate_used_equal(this);
1022   _verifier->verify_region_sets_optional();
1023   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1024   _verifier->check_bitmaps("Full GC Start");
1025 }
1026 
1027 void G1CollectedHeap::prepare_heap_for_mutators() {
1028   hrm()->prepare_for_full_collection_end();
1029 
1030   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1031   ClassLoaderDataGraph::purge();
1032   MetaspaceUtils::verify_metrics();
1033 
1034   // Prepare heap for normal collections.
1035   assert(num_free_regions() == 0, "we should not have added any free regions");
1036   rebuild_region_sets(false /* free_list_only */);
1037   abort_refinement();
1038   resize_heap_if_necessary();
1039 
1040   // Rebuild the strong code root lists for each region
1041   rebuild_strong_code_roots();
1042 
1043   // Purge code root memory
1044   purge_code_root_memory();
1045 
1046   // Start a new incremental collection set for the next pause
1047   start_new_collection_set();
1048 
1049   _allocator->init_mutator_alloc_regions();
1050 
1051   // Post collection state updates.
1052   MetaspaceGC::compute_new_size();
1053 }
1054 
1055 void G1CollectedHeap::abort_refinement() {
1056   if (_hot_card_cache->use_cache()) {
1057     _hot_card_cache->reset_hot_cache();
1058   }
1059 
1060   // Discard all remembered set updates and reset refinement statistics.
1061   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1062   assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1063          "DCQS should be empty");
1064   concurrent_refine()->get_and_reset_refinement_stats();
1065 }
1066 
1067 void G1CollectedHeap::verify_after_full_collection() {
1068   _hrm->verify_optional();
1069   _verifier->verify_region_sets_optional();
1070   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1071   // Clear the previous marking bitmap, if needed for bitmap verification.
1072   // Note we cannot do this when we clear the next marking bitmap in
1073   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1074   // objects marked during a full GC against the previous bitmap.
1075   // But we need to clear it before calling check_bitmaps below since
1076   // the full GC has compacted objects and updated TAMS but not updated
1077   // the prev bitmap.
1078   if (G1VerifyBitmaps) {
1079     GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1080     _cm->clear_prev_bitmap(workers());
1081   }
1082   // This call implicitly verifies that the next bitmap is clear after Full GC.
1083   _verifier->check_bitmaps("Full GC End");
1084 
1085   // At this point there should be no regions in the
1086   // entire heap tagged as young.
1087   assert(check_young_list_empty(), "young list should be empty at this point");
1088 
1089   // Note: since we've just done a full GC, concurrent
1090   // marking is no longer active. Therefore we need not
1091   // re-enable reference discovery for the CM ref processor.
1092   // That will be done at the start of the next marking cycle.
1093   // We also know that the STW processor should no longer
1094   // discover any new references.
1095   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1096   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1097   _ref_processor_stw->verify_no_references_recorded();
1098   _ref_processor_cm->verify_no_references_recorded();
1099 }
1100 
1101 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1102   // Post collection logging.
1103   // We should do this after we potentially resize the heap so
1104   // that all the COMMIT / UNCOMMIT events are generated before
1105   // the compaction events.
1106   print_hrm_post_compaction();
1107   heap_transition->print();
1108   print_heap_after_gc();
1109   print_heap_regions();
1110 }
1111 
1112 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1113                                          bool clear_all_soft_refs) {
1114   assert_at_safepoint_on_vm_thread();
1115 
1116   if (GCLocker::check_active_before_gc()) {
1117     // Full GC was not completed.
1118     return false;
1119   }
1120 
1121   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1122       soft_ref_policy()->should_clear_all_soft_refs();
1123 
1124   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1125   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1126 
1127   collector.prepare_collection();
1128   collector.collect();
1129   collector.complete_collection();
1130 
1131   // Full collection was successfully completed.
1132   return true;
1133 }
1134 
1135 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1136   // Currently, there is no facility in the do_full_collection(bool) API to notify
1137   // the caller that the collection did not succeed (e.g., because it was locked
1138   // out by the GC locker). So, right now, we'll ignore the return value.
1139   bool dummy = do_full_collection(true,                /* explicit_gc */
1140                                   clear_all_soft_refs);
1141 }
1142 
1143 void G1CollectedHeap::resize_heap_if_necessary() {
1144   assert_at_safepoint_on_vm_thread();
1145 
1146   bool should_expand;
1147   size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
1148 
1149   if (resize_amount == 0) {
1150     return;
1151   } else if (should_expand) {
1152     expand(resize_amount, _workers);
1153   } else {
1154     shrink(resize_amount);
1155   }
1156 }
1157 
1158 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1159                                                             bool do_gc,
1160                                                             bool clear_all_soft_refs,
1161                                                             bool expect_null_mutator_alloc_region,
1162                                                             bool* gc_succeeded) {
1163   *gc_succeeded = true;
1164   // Let's attempt the allocation first.
1165   HeapWord* result =
1166     attempt_allocation_at_safepoint(word_size,
1167                                     expect_null_mutator_alloc_region);
1168   if (result != NULL) {
1169     return result;
1170   }
1171 
1172   // In a G1 heap, we're supposed to keep allocation from failing by
1173   // incremental pauses.  Therefore, at least for now, we'll favor
1174   // expansion over collection.  (This might change in the future if we can
1175   // do something smarter than full collection to satisfy a failed alloc.)
1176   result = expand_and_allocate(word_size);
1177   if (result != NULL) {
1178     return result;
1179   }
1180 
1181   if (do_gc) {
1182     // Expansion didn't work, we'll try to do a Full GC.
1183     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1184                                        clear_all_soft_refs);
1185   }
1186 
1187   return NULL;
1188 }
1189 
1190 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1191                                                      bool* succeeded) {
1192   assert_at_safepoint_on_vm_thread();
1193 
1194   // Attempts to allocate followed by Full GC.
1195   HeapWord* result =
1196     satisfy_failed_allocation_helper(word_size,
1197                                      true,  /* do_gc */
1198                                      false, /* clear_all_soft_refs */
1199                                      false, /* expect_null_mutator_alloc_region */
1200                                      succeeded);
1201 
1202   if (result != NULL || !*succeeded) {
1203     return result;
1204   }
1205 
1206   // Attempts to allocate followed by Full GC that will collect all soft references.
1207   result = satisfy_failed_allocation_helper(word_size,
1208                                             true, /* do_gc */
1209                                             true, /* clear_all_soft_refs */
1210                                             true, /* expect_null_mutator_alloc_region */
1211                                             succeeded);
1212 
1213   if (result != NULL || !*succeeded) {
1214     return result;
1215   }
1216 
1217   // Attempts to allocate, no GC
1218   result = satisfy_failed_allocation_helper(word_size,
1219                                             false, /* do_gc */
1220                                             false, /* clear_all_soft_refs */
1221                                             true,  /* expect_null_mutator_alloc_region */
1222                                             succeeded);
1223 
1224   if (result != NULL) {
1225     return result;
1226   }
1227 
1228   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1229          "Flag should have been handled and cleared prior to this point");
1230 
1231   // What else?  We might try synchronous finalization later.  If the total
1232   // space available is large enough for the allocation, then a more
1233   // complete compaction phase than we've tried so far might be
1234   // appropriate.
1235   return NULL;
1236 }
1237 
1238 // Attempting to expand the heap sufficiently
1239 // to support an allocation of the given "word_size".  If
1240 // successful, perform the allocation and return the address of the
1241 // allocated block, or else "NULL".
1242 
1243 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1244   assert_at_safepoint_on_vm_thread();
1245 
1246   _verifier->verify_region_sets_optional();
1247 
1248   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1249   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1250                             word_size * HeapWordSize);
1251 
1252 
1253   if (expand(expand_bytes, _workers)) {
1254     _hrm->verify_optional();
1255     _verifier->verify_region_sets_optional();
1256     return attempt_allocation_at_safepoint(word_size,
1257                                            false /* expect_null_mutator_alloc_region */);
1258   }
1259   return NULL;
1260 }
1261 
1262 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1263   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1264   aligned_expand_bytes = align_up(aligned_expand_bytes,
1265                                        HeapRegion::GrainBytes);
1266 
1267   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1268                             expand_bytes, aligned_expand_bytes);
1269 
1270   if (is_maximal_no_gc()) {
1271     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1272     return false;
1273   }
1274 
1275   double expand_heap_start_time_sec = os::elapsedTime();
1276   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1277   assert(regions_to_expand > 0, "Must expand by at least one region");
1278 
1279   uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1280   if (expand_time_ms != NULL) {
1281     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1282   }
1283 
1284   if (expanded_by > 0) {
1285     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1286     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1287     policy()->record_new_heap_size(num_regions());
1288   } else {
1289     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1290 
1291     // The expansion of the virtual storage space was unsuccessful.
1292     // Let's see if it was because we ran out of swap.
1293     if (G1ExitOnExpansionFailure &&
1294         _hrm->available() >= regions_to_expand) {
1295       // We had head room...
1296       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1297     }
1298   }
1299   return regions_to_expand > 0;
1300 }
1301 
1302 bool G1CollectedHeap::expand_single_region(uint node_index) {
1303   uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1304 
1305   if (expanded_by == 0) {
1306     assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1307     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1308     return false;
1309   }
1310 
1311   policy()->record_new_heap_size(num_regions());
1312   return true;
1313 }
1314 
1315 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1316   size_t aligned_shrink_bytes =
1317     ReservedSpace::page_align_size_down(shrink_bytes);
1318   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1319                                          HeapRegion::GrainBytes);
1320   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1321 
1322   uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1323   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1324 
1325   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",
1326                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1327   if (num_regions_removed > 0) {
1328     policy()->record_new_heap_size(num_regions());
1329   } else {
1330     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1331   }
1332 }
1333 
1334 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1335   _verifier->verify_region_sets_optional();
1336 
1337   // We should only reach here at the end of a Full GC or during Remark which
1338   // means we should not not be holding to any GC alloc regions. The method
1339   // below will make sure of that and do any remaining clean up.
1340   _allocator->abandon_gc_alloc_regions();
1341 
1342   // Instead of tearing down / rebuilding the free lists here, we
1343   // could instead use the remove_all_pending() method on free_list to
1344   // remove only the ones that we need to remove.
1345   tear_down_region_sets(true /* free_list_only */);
1346   shrink_helper(shrink_bytes);
1347   rebuild_region_sets(true /* free_list_only */);
1348 
1349   _hrm->verify_optional();
1350   _verifier->verify_region_sets_optional();
1351 }
1352 
1353 class OldRegionSetChecker : public HeapRegionSetChecker {
1354 public:
1355   void check_mt_safety() {
1356     // Master Old Set MT safety protocol:
1357     // (a) If we're at a safepoint, operations on the master old set
1358     // should be invoked:
1359     // - by the VM thread (which will serialize them), or
1360     // - by the GC workers while holding the FreeList_lock, if we're
1361     //   at a safepoint for an evacuation pause (this lock is taken
1362     //   anyway when an GC alloc region is retired so that a new one
1363     //   is allocated from the free list), or
1364     // - by the GC workers while holding the OldSets_lock, if we're at a
1365     //   safepoint for a cleanup pause.
1366     // (b) If we're not at a safepoint, operations on the master old set
1367     // should be invoked while holding the Heap_lock.
1368 
1369     if (SafepointSynchronize::is_at_safepoint()) {
1370       guarantee(Thread::current()->is_VM_thread() ||
1371                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1372                 "master old set MT safety protocol at a safepoint");
1373     } else {
1374       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1375     }
1376   }
1377   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1378   const char* get_description() { return "Old Regions"; }
1379 };
1380 
1381 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1382 public:
1383   void check_mt_safety() {
1384     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1385               "May only change archive regions during initialization or safepoint.");
1386   }
1387   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1388   const char* get_description() { return "Archive Regions"; }
1389 };
1390 
1391 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1392 public:
1393   void check_mt_safety() {
1394     // Humongous Set MT safety protocol:
1395     // (a) If we're at a safepoint, operations on the master humongous
1396     // set should be invoked by either the VM thread (which will
1397     // serialize them) or by the GC workers while holding the
1398     // OldSets_lock.
1399     // (b) If we're not at a safepoint, operations on the master
1400     // humongous set should be invoked while holding the Heap_lock.
1401 
1402     if (SafepointSynchronize::is_at_safepoint()) {
1403       guarantee(Thread::current()->is_VM_thread() ||
1404                 OldSets_lock->owned_by_self(),
1405                 "master humongous set MT safety protocol at a safepoint");
1406     } else {
1407       guarantee(Heap_lock->owned_by_self(),
1408                 "master humongous set MT safety protocol outside a safepoint");
1409     }
1410   }
1411   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1412   const char* get_description() { return "Humongous Regions"; }
1413 };
1414 
1415 G1CollectedHeap::G1CollectedHeap() :
1416   CollectedHeap(),
1417   _young_gen_sampling_thread(NULL),
1418   _workers(NULL),
1419   _card_table(NULL),
1420   _collection_pause_end(Ticks::now()),
1421   _soft_ref_policy(),
1422   _old_set("Old Region Set", new OldRegionSetChecker()),
1423   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1424   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1425   _bot(NULL),
1426   _listener(),
1427   _numa(G1NUMA::create()),
1428   _hrm(NULL),
1429   _allocator(NULL),
1430   _verifier(NULL),
1431   _summary_bytes_used(0),
1432   _bytes_used_during_gc(0),
1433   _archive_allocator(NULL),
1434   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1435   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1436   _expand_heap_after_alloc_failure(true),
1437   _g1mm(NULL),
1438   _humongous_reclaim_candidates(),
1439   _has_humongous_reclaim_candidates(false),
1440   _hr_printer(),
1441   _collector_state(),
1442   _old_marking_cycles_started(0),
1443   _old_marking_cycles_completed(0),
1444   _eden(),
1445   _survivor(),
1446   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1447   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1448   _policy(G1Policy::create_policy(_gc_timer_stw)),
1449   _heap_sizing_policy(NULL),
1450   _collection_set(this, _policy),
1451   _hot_card_cache(NULL),
1452   _rem_set(NULL),
1453   _cm(NULL),
1454   _cm_thread(NULL),
1455   _cr(NULL),
1456   _task_queues(NULL),
1457   _evacuation_failed(false),
1458   _evacuation_failed_info_array(NULL),
1459   _preserved_marks_set(true /* in_c_heap */),
1460 #ifndef PRODUCT
1461   _evacuation_failure_alot_for_current_gc(false),
1462   _evacuation_failure_alot_gc_number(0),
1463   _evacuation_failure_alot_count(0),
1464 #endif
1465   _ref_processor_stw(NULL),
1466   _is_alive_closure_stw(this),
1467   _is_subject_to_discovery_stw(this),
1468   _ref_processor_cm(NULL),
1469   _is_alive_closure_cm(this),
1470   _is_subject_to_discovery_cm(this),
1471   _region_attr() {
1472 
1473   _verifier = new G1HeapVerifier(this);
1474 
1475   _allocator = new G1Allocator(this);
1476 
1477   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1478 
1479   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1480 
1481   // Override the default _filler_array_max_size so that no humongous filler
1482   // objects are created.
1483   _filler_array_max_size = _humongous_object_threshold_in_words;
1484 
1485   uint n_queues = ParallelGCThreads;
1486   _task_queues = new G1ScannerTasksQueueSet(n_queues);
1487 
1488   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1489 
1490   for (uint i = 0; i < n_queues; i++) {
1491     G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1492     q->initialize();
1493     _task_queues->register_queue(i, q);
1494     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1495   }
1496 
1497   // Initialize the G1EvacuationFailureALot counters and flags.
1498   NOT_PRODUCT(reset_evacuation_should_fail();)
1499   _gc_tracer_stw->initialize();
1500 
1501   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1502 }
1503 
1504 static size_t actual_reserved_page_size(ReservedSpace rs) {
1505   size_t page_size = os::vm_page_size();
1506   if (UseLargePages) {
1507     // There are two ways to manage large page memory.
1508     // 1. OS supports committing large page memory.
1509     // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1510     //    And ReservedSpace calls it 'special'. If we failed to set 'special',
1511     //    we reserved memory without large page.
1512     if (os::can_commit_large_page_memory() || rs.special()) {
1513       // An alignment at ReservedSpace comes from preferred page size or
1514       // heap alignment, and if the alignment came from heap alignment, it could be
1515       // larger than large pages size. So need to cap with the large page size.
1516       page_size = MIN2(rs.alignment(), os::large_page_size());
1517     }
1518   }
1519 
1520   return page_size;
1521 }
1522 
1523 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1524                                                                  size_t size,
1525                                                                  size_t translation_factor) {
1526   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1527   // Allocate a new reserved space, preferring to use large pages.
1528   ReservedSpace rs(size, preferred_page_size);
1529   size_t page_size = actual_reserved_page_size(rs);
1530   G1RegionToSpaceMapper* result  =
1531     G1RegionToSpaceMapper::create_mapper(rs,
1532                                          size,
1533                                          page_size,
1534                                          HeapRegion::GrainBytes,
1535                                          translation_factor,
1536                                          mtGC);
1537 
1538   os::trace_page_sizes_for_requested_size(description,
1539                                           size,
1540                                           preferred_page_size,
1541                                           page_size,
1542                                           rs.base(),
1543                                           rs.size());
1544 
1545   return result;
1546 }
1547 
1548 jint G1CollectedHeap::initialize_concurrent_refinement() {
1549   jint ecode = JNI_OK;
1550   _cr = G1ConcurrentRefine::create(&ecode);
1551   return ecode;
1552 }
1553 
1554 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1555   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1556   if (_young_gen_sampling_thread->osthread() == NULL) {
1557     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1558     return JNI_ENOMEM;
1559   }
1560   return JNI_OK;
1561 }
1562 
1563 jint G1CollectedHeap::initialize() {
1564 
1565   // Necessary to satisfy locking discipline assertions.
1566 
1567   MutexLocker x(Heap_lock);
1568 
1569   // While there are no constraints in the GC code that HeapWordSize
1570   // be any particular value, there are multiple other areas in the
1571   // system which believe this to be true (e.g. oop->object_size in some
1572   // cases incorrectly returns the size in wordSize units rather than
1573   // HeapWordSize).
1574   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1575 
1576   size_t init_byte_size = InitialHeapSize;
1577   size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1578 
1579   // Ensure that the sizes are properly aligned.
1580   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1581   Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1582   Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1583 
1584   // Reserve the maximum.
1585 
1586   // When compressed oops are enabled, the preferred heap base
1587   // is calculated by subtracting the requested size from the
1588   // 32Gb boundary and using the result as the base address for
1589   // heap reservation. If the requested size is not aligned to
1590   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1591   // into the ReservedHeapSpace constructor) then the actual
1592   // base of the reserved heap may end up differing from the
1593   // address that was requested (i.e. the preferred heap base).
1594   // If this happens then we could end up using a non-optimal
1595   // compressed oops mode.
1596 
1597   ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1598                                                      HeapAlignment);
1599 
1600   initialize_reserved_region(heap_rs);
1601 
1602   // Create the barrier set for the entire reserved region.
1603   G1CardTable* ct = new G1CardTable(heap_rs.region());
1604   ct->initialize();
1605   G1BarrierSet* bs = new G1BarrierSet(ct);
1606   bs->initialize();
1607   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1608   BarrierSet::set_barrier_set(bs);
1609   _card_table = ct;
1610 
1611   {
1612     G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1613     satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1614     satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1615   }
1616 
1617   // Create the hot card cache.
1618   _hot_card_cache = new G1HotCardCache(this);
1619 
1620   // Carve out the G1 part of the heap.
1621   ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1622   size_t page_size = actual_reserved_page_size(heap_rs);
1623   G1RegionToSpaceMapper* heap_storage =
1624     G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1625                                               g1_rs.size(),
1626                                               page_size,
1627                                               HeapRegion::GrainBytes,
1628                                               1,
1629                                               mtJavaHeap);
1630   if(heap_storage == NULL) {
1631     vm_shutdown_during_initialization("Could not initialize G1 heap");
1632     return JNI_ERR;
1633   }
1634 
1635   os::trace_page_sizes("Heap",
1636                        MinHeapSize,
1637                        reserved_byte_size,
1638                        page_size,
1639                        heap_rs.base(),
1640                        heap_rs.size());
1641   heap_storage->set_mapping_changed_listener(&_listener);
1642 
1643   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1644   G1RegionToSpaceMapper* bot_storage =
1645     create_aux_memory_mapper("Block Offset Table",
1646                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1647                              G1BlockOffsetTable::heap_map_factor());
1648 
1649   G1RegionToSpaceMapper* cardtable_storage =
1650     create_aux_memory_mapper("Card Table",
1651                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1652                              G1CardTable::heap_map_factor());
1653 
1654   G1RegionToSpaceMapper* card_counts_storage =
1655     create_aux_memory_mapper("Card Counts Table",
1656                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1657                              G1CardCounts::heap_map_factor());
1658 
1659   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1660   G1RegionToSpaceMapper* prev_bitmap_storage =
1661     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1662   G1RegionToSpaceMapper* next_bitmap_storage =
1663     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1664 
1665   _hrm = HeapRegionManager::create_manager(this);
1666 
1667   _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1668   _card_table->initialize(cardtable_storage);
1669 
1670   // Do later initialization work for concurrent refinement.
1671   _hot_card_cache->initialize(card_counts_storage);
1672 
1673   // 6843694 - ensure that the maximum region index can fit
1674   // in the remembered set structures.
1675   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1676   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1677 
1678   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1679   // start within the first card.
1680   guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1681   // Also create a G1 rem set.
1682   _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1683   _rem_set->initialize(max_reserved_capacity(), max_regions());
1684 
1685   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1686   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1687   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1688             "too many cards per region");
1689 
1690   FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1691 
1692   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1693 
1694   {
1695     HeapWord* start = _hrm->reserved().start();
1696     HeapWord* end = _hrm->reserved().end();
1697     size_t granularity = HeapRegion::GrainBytes;
1698 
1699     _region_attr.initialize(start, end, granularity);
1700     _humongous_reclaim_candidates.initialize(start, end, granularity);
1701   }
1702 
1703   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1704                           true /* are_GC_task_threads */,
1705                           false /* are_ConcurrentGC_threads */);
1706   if (_workers == NULL) {
1707     return JNI_ENOMEM;
1708   }
1709   _workers->initialize_workers();
1710 
1711   _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1712 
1713   // Create the G1ConcurrentMark data structure and thread.
1714   // (Must do this late, so that "max_regions" is defined.)
1715   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1716   _cm_thread = _cm->cm_thread();
1717 
1718   // Now expand into the initial heap size.
1719   if (!expand(init_byte_size, _workers)) {
1720     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1721     return JNI_ENOMEM;
1722   }
1723 
1724   // Perform any initialization actions delegated to the policy.
1725   policy()->init(this, &_collection_set);
1726 
1727   jint ecode = initialize_concurrent_refinement();
1728   if (ecode != JNI_OK) {
1729     return ecode;
1730   }
1731 
1732   ecode = initialize_young_gen_sampling_thread();
1733   if (ecode != JNI_OK) {
1734     return ecode;
1735   }
1736 
1737   {
1738     G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1739     dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1740     dcqs.set_max_cards(concurrent_refine()->red_zone());
1741   }
1742 
1743   // Here we allocate the dummy HeapRegion that is required by the
1744   // G1AllocRegion class.
1745   HeapRegion* dummy_region = _hrm->get_dummy_region();
1746 
1747   // We'll re-use the same region whether the alloc region will
1748   // require BOT updates or not and, if it doesn't, then a non-young
1749   // region will complain that it cannot support allocations without
1750   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1751   dummy_region->set_eden();
1752   // Make sure it's full.
1753   dummy_region->set_top(dummy_region->end());
1754   G1AllocRegion::setup(this, dummy_region);
1755 
1756   _allocator->init_mutator_alloc_regions();
1757 
1758   // Do create of the monitoring and management support so that
1759   // values in the heap have been properly initialized.
1760   _g1mm = new G1MonitoringSupport(this);
1761 
1762   G1StringDedup::initialize();
1763 
1764   _preserved_marks_set.init(ParallelGCThreads);
1765 
1766   _collection_set.initialize(max_regions());
1767 
1768   G1InitLogger::print();
1769 
1770   return JNI_OK;
1771 }
1772 
1773 void G1CollectedHeap::stop() {
1774   // Stop all concurrent threads. We do this to make sure these threads
1775   // do not continue to execute and access resources (e.g. logging)
1776   // that are destroyed during shutdown.
1777   _cr->stop();
1778   _young_gen_sampling_thread->stop();
1779   _cm_thread->stop();
1780   if (G1StringDedup::is_enabled()) {
1781     G1StringDedup::stop();
1782   }
1783 }
1784 
1785 void G1CollectedHeap::safepoint_synchronize_begin() {
1786   SuspendibleThreadSet::synchronize();
1787 }
1788 
1789 void G1CollectedHeap::safepoint_synchronize_end() {
1790   SuspendibleThreadSet::desynchronize();
1791 }
1792 
1793 void G1CollectedHeap::post_initialize() {
1794   CollectedHeap::post_initialize();
1795   ref_processing_init();
1796 }
1797 
1798 void G1CollectedHeap::ref_processing_init() {
1799   // Reference processing in G1 currently works as follows:
1800   //
1801   // * There are two reference processor instances. One is
1802   //   used to record and process discovered references
1803   //   during concurrent marking; the other is used to
1804   //   record and process references during STW pauses
1805   //   (both full and incremental).
1806   // * Both ref processors need to 'span' the entire heap as
1807   //   the regions in the collection set may be dotted around.
1808   //
1809   // * For the concurrent marking ref processor:
1810   //   * Reference discovery is enabled at concurrent start.
1811   //   * Reference discovery is disabled and the discovered
1812   //     references processed etc during remarking.
1813   //   * Reference discovery is MT (see below).
1814   //   * Reference discovery requires a barrier (see below).
1815   //   * Reference processing may or may not be MT
1816   //     (depending on the value of ParallelRefProcEnabled
1817   //     and ParallelGCThreads).
1818   //   * A full GC disables reference discovery by the CM
1819   //     ref processor and abandons any entries on it's
1820   //     discovered lists.
1821   //
1822   // * For the STW processor:
1823   //   * Non MT discovery is enabled at the start of a full GC.
1824   //   * Processing and enqueueing during a full GC is non-MT.
1825   //   * During a full GC, references are processed after marking.
1826   //
1827   //   * Discovery (may or may not be MT) is enabled at the start
1828   //     of an incremental evacuation pause.
1829   //   * References are processed near the end of a STW evacuation pause.
1830   //   * For both types of GC:
1831   //     * Discovery is atomic - i.e. not concurrent.
1832   //     * Reference discovery will not need a barrier.
1833 
1834   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1835 
1836   // Concurrent Mark ref processor
1837   _ref_processor_cm =
1838     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1839                            mt_processing,                                  // mt processing
1840                            ParallelGCThreads,                              // degree of mt processing
1841                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1842                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1843                            false,                                          // Reference discovery is not atomic
1844                            &_is_alive_closure_cm,                          // is alive closure
1845                            true);                                          // allow changes to number of processing threads
1846 
1847   // STW ref processor
1848   _ref_processor_stw =
1849     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1850                            mt_processing,                        // mt processing
1851                            ParallelGCThreads,                    // degree of mt processing
1852                            (ParallelGCThreads > 1),              // mt discovery
1853                            ParallelGCThreads,                    // degree of mt discovery
1854                            true,                                 // Reference discovery is atomic
1855                            &_is_alive_closure_stw,               // is alive closure
1856                            true);                                // allow changes to number of processing threads
1857 }
1858 
1859 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1860   return &_soft_ref_policy;
1861 }
1862 
1863 size_t G1CollectedHeap::capacity() const {
1864   return _hrm->length() * HeapRegion::GrainBytes;
1865 }
1866 
1867 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1868   return _hrm->total_free_bytes();
1869 }
1870 
1871 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1872   _hot_card_cache->drain(cl, worker_id);
1873 }
1874 
1875 // Computes the sum of the storage used by the various regions.
1876 size_t G1CollectedHeap::used() const {
1877   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1878   if (_archive_allocator != NULL) {
1879     result += _archive_allocator->used();
1880   }
1881   return result;
1882 }
1883 
1884 size_t G1CollectedHeap::used_unlocked() const {
1885   return _summary_bytes_used;
1886 }
1887 
1888 class SumUsedClosure: public HeapRegionClosure {
1889   size_t _used;
1890 public:
1891   SumUsedClosure() : _used(0) {}
1892   bool do_heap_region(HeapRegion* r) {
1893     _used += r->used();
1894     return false;
1895   }
1896   size_t result() { return _used; }
1897 };
1898 
1899 size_t G1CollectedHeap::recalculate_used() const {
1900   SumUsedClosure blk;
1901   heap_region_iterate(&blk);
1902   return blk.result();
1903 }
1904 
1905 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1906   switch (cause) {
1907     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1908     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1909     case GCCause::_wb_conc_mark:                        return true;
1910     default :                                           return false;
1911   }
1912 }
1913 
1914 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1915   switch (cause) {
1916     case GCCause::_g1_humongous_allocation: return true;
1917     case GCCause::_g1_periodic_collection:  return G1PeriodicGCInvokesConcurrent;
1918     case GCCause::_wb_breakpoint:           return true;
1919     default:                                return is_user_requested_concurrent_full_gc(cause);
1920   }
1921 }
1922 
1923 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
1924   if (policy()->force_upgrade_to_full()) {
1925     return true;
1926   } else if (should_do_concurrent_full_gc(_gc_cause)) {
1927     return false;
1928   } else if (has_regions_left_for_allocation()) {
1929     return false;
1930   } else {
1931     return true;
1932   }
1933 }
1934 
1935 #ifndef PRODUCT
1936 void G1CollectedHeap::allocate_dummy_regions() {
1937   // Let's fill up most of the region
1938   size_t word_size = HeapRegion::GrainWords - 1024;
1939   // And as a result the region we'll allocate will be humongous.
1940   guarantee(is_humongous(word_size), "sanity");
1941 
1942   // _filler_array_max_size is set to humongous object threshold
1943   // but temporarily change it to use CollectedHeap::fill_with_object().
1944   AutoModifyRestore<size_t> temporarily(_filler_array_max_size, word_size);
1945 
1946   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1947     // Let's use the existing mechanism for the allocation
1948     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1949     if (dummy_obj != NULL) {
1950       MemRegion mr(dummy_obj, word_size);
1951       CollectedHeap::fill_with_object(mr);
1952     } else {
1953       // If we can't allocate once, we probably cannot allocate
1954       // again. Let's get out of the loop.
1955       break;
1956     }
1957   }
1958 }
1959 #endif // !PRODUCT
1960 
1961 void G1CollectedHeap::increment_old_marking_cycles_started() {
1962   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1963          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1964          "Wrong marking cycle count (started: %d, completed: %d)",
1965          _old_marking_cycles_started, _old_marking_cycles_completed);
1966 
1967   _old_marking_cycles_started++;
1968 }
1969 
1970 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1971                                                              bool whole_heap_examined) {
1972   MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1973 
1974   // We assume that if concurrent == true, then the caller is a
1975   // concurrent thread that was joined the Suspendible Thread
1976   // Set. If there's ever a cheap way to check this, we should add an
1977   // assert here.
1978 
1979   // Given that this method is called at the end of a Full GC or of a
1980   // concurrent cycle, and those can be nested (i.e., a Full GC can
1981   // interrupt a concurrent cycle), the number of full collections
1982   // completed should be either one (in the case where there was no
1983   // nesting) or two (when a Full GC interrupted a concurrent cycle)
1984   // behind the number of full collections started.
1985 
1986   // This is the case for the inner caller, i.e. a Full GC.
1987   assert(concurrent ||
1988          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1989          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1990          "for inner caller (Full GC): _old_marking_cycles_started = %u "
1991          "is inconsistent with _old_marking_cycles_completed = %u",
1992          _old_marking_cycles_started, _old_marking_cycles_completed);
1993 
1994   // This is the case for the outer caller, i.e. the concurrent cycle.
1995   assert(!concurrent ||
1996          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1997          "for outer caller (concurrent cycle): "
1998          "_old_marking_cycles_started = %u "
1999          "is inconsistent with _old_marking_cycles_completed = %u",
2000          _old_marking_cycles_started, _old_marking_cycles_completed);
2001 
2002   _old_marking_cycles_completed += 1;
2003   if (whole_heap_examined) {
2004     next_whole_heap_examined();
2005   }
2006 
2007   // We need to clear the "in_progress" flag in the CM thread before
2008   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2009   // is set) so that if a waiter requests another System.gc() it doesn't
2010   // incorrectly see that a marking cycle is still in progress.
2011   if (concurrent) {
2012     _cm_thread->set_idle();
2013   }
2014 
2015   // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2016   // for a full GC to finish that their wait is over.
2017   ml.notify_all();
2018 }
2019 
2020 void G1CollectedHeap::collect(GCCause::Cause cause) {
2021   try_collect(cause);
2022 }
2023 
2024 // Return true if (x < y) with allowance for wraparound.
2025 static bool gc_counter_less_than(uint x, uint y) {
2026   return (x - y) > (UINT_MAX/2);
2027 }
2028 
2029 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2030 // Macro so msg printing is format-checked.
2031 #define LOG_COLLECT_CONCURRENTLY(cause, ...)                            \
2032   do {                                                                  \
2033     LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt;                   \
2034     if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) {                     \
2035       ResourceMark rm; /* For thread name. */                           \
2036       LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2037       LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2038                                        Thread::current()->name(),       \
2039                                        GCCause::to_string(cause));      \
2040       LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__);                    \
2041     }                                                                   \
2042   } while (0)
2043 
2044 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2045   LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2046 
2047 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2048                                                uint gc_counter,
2049                                                uint old_marking_started_before) {
2050   assert_heap_not_locked();
2051   assert(should_do_concurrent_full_gc(cause),
2052          "Non-concurrent cause %s", GCCause::to_string(cause));
2053 
2054   for (uint i = 1; true; ++i) {
2055     // Try to schedule concurrent start evacuation pause that will
2056     // start a concurrent cycle.
2057     LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2058     VM_G1TryInitiateConcMark op(gc_counter,
2059                                 cause,
2060                                 policy()->max_pause_time_ms());
2061     VMThread::execute(&op);
2062 
2063     // Request is trivially finished.
2064     if (cause == GCCause::_g1_periodic_collection) {
2065       LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2066       return op.gc_succeeded();
2067     }
2068 
2069     // If VMOp skipped initiating concurrent marking cycle because
2070     // we're terminating, then we're done.
2071     if (op.terminating()) {
2072       LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2073       return false;
2074     }
2075 
2076     // Lock to get consistent set of values.
2077     uint old_marking_started_after;
2078     uint old_marking_completed_after;
2079     {
2080       MutexLocker ml(Heap_lock);
2081       // Update gc_counter for retrying VMOp if needed. Captured here to be
2082       // consistent with the values we use below for termination tests.  If
2083       // a retry is needed after a possible wait, and another collection
2084       // occurs in the meantime, it will cause our retry to be skipped and
2085       // we'll recheck for termination with updated conditions from that
2086       // more recent collection.  That's what we want, rather than having
2087       // our retry possibly perform an unnecessary collection.
2088       gc_counter = total_collections();
2089       old_marking_started_after = _old_marking_cycles_started;
2090       old_marking_completed_after = _old_marking_cycles_completed;
2091     }
2092 
2093     if (cause == GCCause::_wb_breakpoint) {
2094       if (op.gc_succeeded()) {
2095         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2096         return true;
2097       }
2098       // When _wb_breakpoint there can't be another cycle or deferred.
2099       assert(!op.cycle_already_in_progress(), "invariant");
2100       assert(!op.whitebox_attached(), "invariant");
2101       // Concurrent cycle attempt might have been cancelled by some other
2102       // collection, so retry.  Unlike other cases below, we want to retry
2103       // even if cancelled by a STW full collection, because we really want
2104       // to start a concurrent cycle.
2105       if (old_marking_started_before != old_marking_started_after) {
2106         LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2107         old_marking_started_before = old_marking_started_after;
2108       }
2109     } else if (!GCCause::is_user_requested_gc(cause)) {
2110       // For an "automatic" (not user-requested) collection, we just need to
2111       // ensure that progress is made.
2112       //
2113       // Request is finished if any of
2114       // (1) the VMOp successfully performed a GC,
2115       // (2) a concurrent cycle was already in progress,
2116       // (3) whitebox is controlling concurrent cycles,
2117       // (4) a new cycle was started (by this thread or some other), or
2118       // (5) a Full GC was performed.
2119       // Cases (4) and (5) are detected together by a change to
2120       // _old_marking_cycles_started.
2121       //
2122       // Note that (1) does not imply (4).  If we're still in the mixed
2123       // phase of an earlier concurrent collection, the request to make the
2124       // collection a concurrent start won't be honored.  If we don't check for
2125       // both conditions we'll spin doing back-to-back collections.
2126       if (op.gc_succeeded() ||
2127           op.cycle_already_in_progress() ||
2128           op.whitebox_attached() ||
2129           (old_marking_started_before != old_marking_started_after)) {
2130         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2131         return true;
2132       }
2133     } else {                    // User-requested GC.
2134       // For a user-requested collection, we want to ensure that a complete
2135       // full collection has been performed before returning, but without
2136       // waiting for more than needed.
2137 
2138       // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2139       // new cycle was started.  That's good, because it's not clear what we
2140       // should do otherwise.  Trying again just does back to back GCs.
2141       // Can't wait for someone else to start a cycle.  And returning fails
2142       // to meet the goal of ensuring a full collection was performed.
2143       assert(!op.gc_succeeded() ||
2144              (old_marking_started_before != old_marking_started_after),
2145              "invariant: succeeded %s, started before %u, started after %u",
2146              BOOL_TO_STR(op.gc_succeeded()),
2147              old_marking_started_before, old_marking_started_after);
2148 
2149       // Request is finished if a full collection (concurrent or stw)
2150       // was started after this request and has completed, e.g.
2151       // started_before < completed_after.
2152       if (gc_counter_less_than(old_marking_started_before,
2153                                old_marking_completed_after)) {
2154         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2155         return true;
2156       }
2157 
2158       if (old_marking_started_after != old_marking_completed_after) {
2159         // If there is an in-progress cycle (possibly started by us), then
2160         // wait for that cycle to complete, e.g.
2161         // while completed_now < started_after.
2162         LOG_COLLECT_CONCURRENTLY(cause, "wait");
2163         MonitorLocker ml(G1OldGCCount_lock);
2164         while (gc_counter_less_than(_old_marking_cycles_completed,
2165                                     old_marking_started_after)) {
2166           ml.wait();
2167         }
2168         // Request is finished if the collection we just waited for was
2169         // started after this request.
2170         if (old_marking_started_before != old_marking_started_after) {
2171           LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2172           return true;
2173         }
2174       }
2175 
2176       // If VMOp was successful then it started a new cycle that the above
2177       // wait &etc should have recognized as finishing this request.  This
2178       // differs from a non-user-request, where gc_succeeded does not imply
2179       // a new cycle was started.
2180       assert(!op.gc_succeeded(), "invariant");
2181 
2182       if (op.cycle_already_in_progress()) {
2183         // If VMOp failed because a cycle was already in progress, it
2184         // is now complete.  But it didn't finish this user-requested
2185         // GC, so try again.
2186         LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2187         continue;
2188       } else if (op.whitebox_attached()) {
2189         // If WhiteBox wants control, wait for notification of a state
2190         // change in the controller, then try again.  Don't wait for
2191         // release of control, since collections may complete while in
2192         // control.  Note: This won't recognize a STW full collection
2193         // while waiting; we can't wait on multiple monitors.
2194         LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2195         MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2196         if (ConcurrentGCBreakpoints::is_controlled()) {
2197           ml.wait();
2198         }
2199         continue;
2200       }
2201     }
2202 
2203     // Collection failed and should be retried.
2204     assert(op.transient_failure(), "invariant");
2205 
2206     if (GCLocker::is_active_and_needs_gc()) {
2207       // If GCLocker is active, wait until clear before retrying.
2208       LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2209       GCLocker::stall_until_clear();
2210     }
2211 
2212     LOG_COLLECT_CONCURRENTLY(cause, "retry");
2213   }
2214 }
2215 
2216 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2217   assert_heap_not_locked();
2218 
2219   // Lock to get consistent set of values.
2220   uint gc_count_before;
2221   uint full_gc_count_before;
2222   uint old_marking_started_before;
2223   {
2224     MutexLocker ml(Heap_lock);
2225     gc_count_before = total_collections();
2226     full_gc_count_before = total_full_collections();
2227     old_marking_started_before = _old_marking_cycles_started;
2228   }
2229 
2230   if (should_do_concurrent_full_gc(cause)) {
2231     return try_collect_concurrently(cause,
2232                                     gc_count_before,
2233                                     old_marking_started_before);
2234   } else if (GCLocker::should_discard(cause, gc_count_before)) {
2235     // Indicate failure to be consistent with VMOp failure due to
2236     // another collection slipping in after our gc_count but before
2237     // our request is processed.
2238     return false;
2239   } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2240              DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2241 
2242     // Schedule a standard evacuation pause. We're setting word_size
2243     // to 0 which means that we are not requesting a post-GC allocation.
2244     VM_G1CollectForAllocation op(0,     /* word_size */
2245                                  gc_count_before,
2246                                  cause,
2247                                  policy()->max_pause_time_ms());
2248     VMThread::execute(&op);
2249     return op.gc_succeeded();
2250   } else {
2251     // Schedule a Full GC.
2252     VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2253     VMThread::execute(&op);
2254     return op.gc_succeeded();
2255   }
2256 }
2257 
2258 bool G1CollectedHeap::is_in(const void* p) const {
2259   if (_hrm->reserved().contains(p)) {
2260     // Given that we know that p is in the reserved space,
2261     // heap_region_containing() should successfully
2262     // return the containing region.
2263     HeapRegion* hr = heap_region_containing(p);
2264     return hr->is_in(p);
2265   } else {
2266     return false;
2267   }
2268 }
2269 
2270 #ifdef ASSERT
2271 bool G1CollectedHeap::is_in_exact(const void* p) const {
2272   bool contains = reserved_region().contains(p);
2273   bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2274   if (contains && available) {
2275     return true;
2276   } else {
2277     return false;
2278   }
2279 }
2280 #endif
2281 
2282 // Iteration functions.
2283 
2284 // Iterates an ObjectClosure over all objects within a HeapRegion.
2285 
2286 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2287   ObjectClosure* _cl;
2288 public:
2289   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2290   bool do_heap_region(HeapRegion* r) {
2291     if (!r->is_continues_humongous()) {
2292       r->object_iterate(_cl);
2293     }
2294     return false;
2295   }
2296 };
2297 
2298 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2299   IterateObjectClosureRegionClosure blk(cl);
2300   heap_region_iterate(&blk);
2301 }
2302 
2303 void G1CollectedHeap::keep_alive(oop obj) {
2304   G1BarrierSet::enqueue(obj);
2305 }
2306 
2307 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2308   _hrm->iterate(cl);
2309 }
2310 
2311 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2312                                                                  HeapRegionClaimer *hrclaimer,
2313                                                                  uint worker_id) const {
2314   _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2315 }
2316 
2317 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2318                                                          HeapRegionClaimer *hrclaimer) const {
2319   _hrm->par_iterate(cl, hrclaimer, 0);
2320 }
2321 
2322 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2323   _collection_set.iterate(cl);
2324 }
2325 
2326 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2327   _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2328 }
2329 
2330 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2331   _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2332 }
2333 
2334 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2335   HeapRegion* hr = heap_region_containing(addr);
2336   return hr->block_start(addr);
2337 }
2338 
2339 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2340   HeapRegion* hr = heap_region_containing(addr);
2341   return hr->block_is_obj(addr);
2342 }
2343 
2344 bool G1CollectedHeap::supports_tlab_allocation() const {
2345   return true;
2346 }
2347 
2348 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2349   return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2350 }
2351 
2352 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2353   return _eden.length() * HeapRegion::GrainBytes;
2354 }
2355 
2356 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2357 // must be equal to the humongous object limit.
2358 size_t G1CollectedHeap::max_tlab_size() const {
2359   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2360 }
2361 
2362 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2363   return _allocator->unsafe_max_tlab_alloc();
2364 }
2365 
2366 size_t G1CollectedHeap::max_capacity() const {
2367   return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2368 }
2369 
2370 size_t G1CollectedHeap::max_reserved_capacity() const {
2371   return _hrm->max_length() * HeapRegion::GrainBytes;
2372 }
2373 
2374 void G1CollectedHeap::deduplicate_string(oop str) {
2375   assert(java_lang_String::is_instance(str), "invariant");
2376 
2377   if (G1StringDedup::is_enabled()) {
2378     G1StringDedup::deduplicate(str);
2379   }
2380 }
2381 
2382 void G1CollectedHeap::prepare_for_verify() {
2383   _verifier->prepare_for_verify();
2384 }
2385 
2386 void G1CollectedHeap::verify(VerifyOption vo) {
2387   _verifier->verify(vo);
2388 }
2389 
2390 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2391   return true;
2392 }
2393 
2394 bool G1CollectedHeap::is_heterogeneous_heap() const {
2395   return G1Arguments::is_heterogeneous_heap();
2396 }
2397 
2398 class PrintRegionClosure: public HeapRegionClosure {
2399   outputStream* _st;
2400 public:
2401   PrintRegionClosure(outputStream* st) : _st(st) {}
2402   bool do_heap_region(HeapRegion* r) {
2403     r->print_on(_st);
2404     return false;
2405   }
2406 };
2407 
2408 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2409                                        const HeapRegion* hr,
2410                                        const VerifyOption vo) const {
2411   switch (vo) {
2412   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2413   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2414   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2415   default:                            ShouldNotReachHere();
2416   }
2417   return false; // keep some compilers happy
2418 }
2419 
2420 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2421                                        const VerifyOption vo) const {
2422   switch (vo) {
2423   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2424   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2425   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2426   default:                            ShouldNotReachHere();
2427   }
2428   return false; // keep some compilers happy
2429 }
2430 
2431 void G1CollectedHeap::print_heap_regions() const {
2432   LogTarget(Trace, gc, heap, region) lt;
2433   if (lt.is_enabled()) {
2434     LogStream ls(lt);
2435     print_regions_on(&ls);
2436   }
2437 }
2438 
2439 void G1CollectedHeap::print_on(outputStream* st) const {
2440   st->print(" %-20s", "garbage-first heap");
2441   if (_hrm != NULL) {
2442     st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2443               capacity()/K, used_unlocked()/K);
2444     st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2445               p2i(_hrm->reserved().start()),
2446               p2i(_hrm->reserved().end()));
2447   }
2448   st->cr();
2449   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2450   uint young_regions = young_regions_count();
2451   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2452             (size_t) young_regions * HeapRegion::GrainBytes / K);
2453   uint survivor_regions = survivor_regions_count();
2454   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2455             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2456   st->cr();
2457   if (_numa->is_enabled()) {
2458     uint num_nodes = _numa->num_active_nodes();
2459     st->print("  remaining free region(s) on each NUMA node: ");
2460     const int* node_ids = _numa->node_ids();
2461     for (uint node_index = 0; node_index < num_nodes; node_index++) {
2462       uint num_free_regions = (_hrm != NULL ? _hrm->num_free_regions(node_index) : 0);
2463       st->print("%d=%u ", node_ids[node_index], num_free_regions);
2464     }
2465     st->cr();
2466   }
2467   MetaspaceUtils::print_on(st);
2468 }
2469 
2470 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2471   if (_hrm == NULL) {
2472     return;
2473   }
2474 
2475   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2476                "HS=humongous(starts), HC=humongous(continues), "
2477                "CS=collection set, F=free, "
2478                "OA=open archive, CA=closed archive, "
2479                "TAMS=top-at-mark-start (previous, next)");
2480   PrintRegionClosure blk(st);
2481   heap_region_iterate(&blk);
2482 }
2483 
2484 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2485   print_on(st);
2486 
2487   // Print the per-region information.
2488   if (_hrm != NULL) {
2489     st->cr();
2490     print_regions_on(st);
2491   }
2492 }
2493 
2494 void G1CollectedHeap::print_on_error(outputStream* st) const {
2495   this->CollectedHeap::print_on_error(st);
2496 
2497   if (_cm != NULL) {
2498     st->cr();
2499     _cm->print_on_error(st);
2500   }
2501 }
2502 
2503 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2504   workers()->threads_do(tc);
2505   tc->do_thread(_cm_thread);
2506   _cm->threads_do(tc);
2507   _cr->threads_do(tc);
2508   tc->do_thread(_young_gen_sampling_thread);
2509   if (G1StringDedup::is_enabled()) {
2510     G1StringDedup::threads_do(tc);
2511   }
2512 }
2513 
2514 void G1CollectedHeap::print_tracing_info() const {
2515   rem_set()->print_summary_info();
2516   concurrent_mark()->print_summary_info();
2517 }
2518 
2519 #ifndef PRODUCT
2520 // Helpful for debugging RSet issues.
2521 
2522 class PrintRSetsClosure : public HeapRegionClosure {
2523 private:
2524   const char* _msg;
2525   size_t _occupied_sum;
2526 
2527 public:
2528   bool do_heap_region(HeapRegion* r) {
2529     HeapRegionRemSet* hrrs = r->rem_set();
2530     size_t occupied = hrrs->occupied();
2531     _occupied_sum += occupied;
2532 
2533     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2534     if (occupied == 0) {
2535       tty->print_cr("  RSet is empty");
2536     } else {
2537       hrrs->print();
2538     }
2539     tty->print_cr("----------");
2540     return false;
2541   }
2542 
2543   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2544     tty->cr();
2545     tty->print_cr("========================================");
2546     tty->print_cr("%s", msg);
2547     tty->cr();
2548   }
2549 
2550   ~PrintRSetsClosure() {
2551     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2552     tty->print_cr("========================================");
2553     tty->cr();
2554   }
2555 };
2556 
2557 void G1CollectedHeap::print_cset_rsets() {
2558   PrintRSetsClosure cl("Printing CSet RSets");
2559   collection_set_iterate_all(&cl);
2560 }
2561 
2562 void G1CollectedHeap::print_all_rsets() {
2563   PrintRSetsClosure cl("Printing All RSets");;
2564   heap_region_iterate(&cl);
2565 }
2566 #endif // PRODUCT
2567 
2568 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2569   return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2570 }
2571 
2572 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2573 
2574   size_t eden_used_bytes = _eden.used_bytes();
2575   size_t survivor_used_bytes = _survivor.used_bytes();
2576   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2577 
2578   size_t eden_capacity_bytes =
2579     (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2580 
2581   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2582   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2583                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2584 }
2585 
2586 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2587   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2588                        stats->unused(), stats->used(), stats->region_end_waste(),
2589                        stats->regions_filled(), stats->direct_allocated(),
2590                        stats->failure_used(), stats->failure_waste());
2591 }
2592 
2593 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2594   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2595   gc_tracer->report_gc_heap_summary(when, heap_summary);
2596 
2597   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2598   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2599 }
2600 
2601 void G1CollectedHeap::gc_prologue(bool full) {
2602   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2603 
2604   // This summary needs to be printed before incrementing total collections.
2605   rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2606 
2607   // Update common counters.
2608   increment_total_collections(full /* full gc */);
2609   if (full || collector_state()->in_concurrent_start_gc()) {
2610     increment_old_marking_cycles_started();
2611   }
2612 
2613   // Fill TLAB's and such
2614   {
2615     Ticks start = Ticks::now();
2616     ensure_parsability(true);
2617     Tickspan dt = Ticks::now() - start;
2618     phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS);
2619   }
2620 
2621   if (!full) {
2622     // Flush dirty card queues to qset, so later phases don't need to account
2623     // for partially filled per-thread queues and such.  Not needed for full
2624     // collections, which ignore those logs.
2625     Ticks start = Ticks::now();
2626     G1BarrierSet::dirty_card_queue_set().concatenate_logs();
2627     Tickspan dt = Ticks::now() - start;
2628     phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS);
2629   }
2630 }
2631 
2632 void G1CollectedHeap::gc_epilogue(bool full) {
2633   // Update common counters.
2634   if (full) {
2635     // Update the number of full collections that have been completed.
2636     increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2637   }
2638 
2639   // We are at the end of the GC. Total collections has already been increased.
2640   rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2641 
2642   // FIXME: what is this about?
2643   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2644   // is set.
2645 #if COMPILER2_OR_JVMCI
2646   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2647 #endif
2648 
2649   double start = os::elapsedTime();
2650   resize_all_tlabs();
2651   phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2652 
2653   MemoryService::track_memory_usage();
2654   // We have just completed a GC. Update the soft reference
2655   // policy with the new heap occupancy
2656   Universe::update_heap_info_at_gc();
2657 
2658   // Print NUMA statistics.
2659   _numa->print_statistics();
2660 
2661   _collection_pause_end = Ticks::now();
2662 }
2663 
2664 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2665   LogTarget(Trace, gc, heap, verify) lt;
2666 
2667   if (lt.is_enabled()) {
2668     LogStream ls(lt);
2669     // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2670     G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2671     heap_region_iterate(&cl);
2672   }
2673 }
2674 
2675 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2676                                                uint gc_count_before,
2677                                                bool* succeeded,
2678                                                GCCause::Cause gc_cause) {
2679   assert_heap_not_locked_and_not_at_safepoint();
2680   VM_G1CollectForAllocation op(word_size,
2681                                gc_count_before,
2682                                gc_cause,
2683                                policy()->max_pause_time_ms());
2684   VMThread::execute(&op);
2685 
2686   HeapWord* result = op.result();
2687   bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2688   assert(result == NULL || ret_succeeded,
2689          "the result should be NULL if the VM did not succeed");
2690   *succeeded = ret_succeeded;
2691 
2692   assert_heap_not_locked();
2693   return result;
2694 }
2695 
2696 void G1CollectedHeap::do_concurrent_mark() {
2697   MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2698   if (!_cm_thread->in_progress()) {
2699     _cm_thread->set_started();
2700     CGC_lock->notify();
2701   }
2702 }
2703 
2704 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2705   // We don't nominate objects with many remembered set entries, on
2706   // the assumption that such objects are likely still live.
2707   HeapRegionRemSet* rem_set = r->rem_set();
2708 
2709   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2710          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2711          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2712 }
2713 
2714 #ifndef PRODUCT
2715 void G1CollectedHeap::verify_region_attr_remset_update() {
2716   class VerifyRegionAttrRemSet : public HeapRegionClosure {
2717   public:
2718     virtual bool do_heap_region(HeapRegion* r) {
2719       G1CollectedHeap* g1h = G1CollectedHeap::heap();
2720       bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2721       assert(r->rem_set()->is_tracked() == needs_remset_update,
2722              "Region %u remset tracking status (%s) different to region attribute (%s)",
2723              r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2724       return false;
2725     }
2726   } cl;
2727   heap_region_iterate(&cl);
2728 }
2729 #endif
2730 
2731 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2732   public:
2733     bool do_heap_region(HeapRegion* hr) {
2734       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2735         hr->verify_rem_set();
2736       }
2737       return false;
2738     }
2739 };
2740 
2741 uint G1CollectedHeap::num_task_queues() const {
2742   return _task_queues->size();
2743 }
2744 
2745 #if TASKQUEUE_STATS
2746 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2747   st->print_raw_cr("GC Task Stats");
2748   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2749   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2750 }
2751 
2752 void G1CollectedHeap::print_taskqueue_stats() const {
2753   if (!log_is_enabled(Trace, gc, task, stats)) {
2754     return;
2755   }
2756   Log(gc, task, stats) log;
2757   ResourceMark rm;
2758   LogStream ls(log.trace());
2759   outputStream* st = &ls;
2760 
2761   print_taskqueue_stats_hdr(st);
2762 
2763   TaskQueueStats totals;
2764   const uint n = num_task_queues();
2765   for (uint i = 0; i < n; ++i) {
2766     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2767     totals += task_queue(i)->stats;
2768   }
2769   st->print_raw("tot "); totals.print(st); st->cr();
2770 
2771   DEBUG_ONLY(totals.verify());
2772 }
2773 
2774 void G1CollectedHeap::reset_taskqueue_stats() {
2775   const uint n = num_task_queues();
2776   for (uint i = 0; i < n; ++i) {
2777     task_queue(i)->stats.reset();
2778   }
2779 }
2780 #endif // TASKQUEUE_STATS
2781 
2782 void G1CollectedHeap::wait_for_root_region_scanning() {
2783   double scan_wait_start = os::elapsedTime();
2784   // We have to wait until the CM threads finish scanning the
2785   // root regions as it's the only way to ensure that all the
2786   // objects on them have been correctly scanned before we start
2787   // moving them during the GC.
2788   bool waited = _cm->root_regions()->wait_until_scan_finished();
2789   double wait_time_ms = 0.0;
2790   if (waited) {
2791     double scan_wait_end = os::elapsedTime();
2792     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2793   }
2794   phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2795 }
2796 
2797 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2798 private:
2799   G1HRPrinter* _hr_printer;
2800 public:
2801   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2802 
2803   virtual bool do_heap_region(HeapRegion* r) {
2804     _hr_printer->cset(r);
2805     return false;
2806   }
2807 };
2808 
2809 void G1CollectedHeap::start_new_collection_set() {
2810   double start = os::elapsedTime();
2811 
2812   collection_set()->start_incremental_building();
2813 
2814   clear_region_attr();
2815 
2816   guarantee(_eden.length() == 0, "eden should have been cleared");
2817   policy()->transfer_survivors_to_cset(survivor());
2818 
2819   // We redo the verification but now wrt to the new CSet which
2820   // has just got initialized after the previous CSet was freed.
2821   _cm->verify_no_collection_set_oops();
2822 
2823   phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2824 }
2825 
2826 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2827 
2828   _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2829   evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2830                                             collection_set()->optional_region_length());
2831 
2832   _cm->verify_no_collection_set_oops();
2833 
2834   if (_hr_printer.is_active()) {
2835     G1PrintCollectionSetClosure cl(&_hr_printer);
2836     _collection_set.iterate(&cl);
2837     _collection_set.iterate_optional(&cl);
2838   }
2839 }
2840 
2841 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2842   if (collector_state()->in_concurrent_start_gc()) {
2843     return G1HeapVerifier::G1VerifyConcurrentStart;
2844   } else if (collector_state()->in_young_only_phase()) {
2845     return G1HeapVerifier::G1VerifyYoungNormal;
2846   } else {
2847     return G1HeapVerifier::G1VerifyMixed;
2848   }
2849 }
2850 
2851 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2852   if (VerifyRememberedSets) {
2853     log_info(gc, verify)("[Verifying RemSets before GC]");
2854     VerifyRegionRemSetClosure v_cl;
2855     heap_region_iterate(&v_cl);
2856   }
2857   _verifier->verify_before_gc(type);
2858   _verifier->check_bitmaps("GC Start");
2859   verify_numa_regions("GC Start");
2860 }
2861 
2862 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2863   if (VerifyRememberedSets) {
2864     log_info(gc, verify)("[Verifying RemSets after GC]");
2865     VerifyRegionRemSetClosure v_cl;
2866     heap_region_iterate(&v_cl);
2867   }
2868   _verifier->verify_after_gc(type);
2869   _verifier->check_bitmaps("GC End");
2870   verify_numa_regions("GC End");
2871 }
2872 
2873 void G1CollectedHeap::expand_heap_after_young_collection(){
2874   size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2875   if (expand_bytes > 0) {
2876     // No need for an ergo logging here,
2877     // expansion_amount() does this when it returns a value > 0.
2878     double expand_ms;
2879     if (!expand(expand_bytes, _workers, &expand_ms)) {
2880       // We failed to expand the heap. Cannot do anything about it.
2881     }
2882     phase_times()->record_expand_heap_time(expand_ms);
2883   }
2884 }
2885 
2886 const char* G1CollectedHeap::young_gc_name() const {
2887   if (collector_state()->in_concurrent_start_gc()) {
2888     return "Pause Young (Concurrent Start)";
2889   } else if (collector_state()->in_young_only_phase()) {
2890     if (collector_state()->in_young_gc_before_mixed()) {
2891       return "Pause Young (Prepare Mixed)";
2892     } else {
2893       return "Pause Young (Normal)";
2894     }
2895   } else {
2896     return "Pause Young (Mixed)";
2897   }
2898 }
2899 
2900 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2901   assert_at_safepoint_on_vm_thread();
2902   guarantee(!is_gc_active(), "collection is not reentrant");
2903 
2904   if (GCLocker::check_active_before_gc()) {
2905     return false;
2906   }
2907 
2908   do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2909   if (should_upgrade_to_full_gc(gc_cause())) {
2910     log_info(gc, ergo)("Attempting maximally compacting collection");
2911     bool result = do_full_collection(false /* explicit gc */,
2912                                      true /* clear_all_soft_refs */);
2913     // do_full_collection only fails if blocked by GC locker, but
2914     // we've already checked for that above.
2915     assert(result, "invariant");
2916   }
2917   return true;
2918 }
2919 
2920 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2921   GCIdMark gc_id_mark;
2922 
2923   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2924   ResourceMark rm;
2925 
2926   policy()->note_gc_start();
2927 
2928   _gc_timer_stw->register_gc_start();
2929   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2930 
2931   wait_for_root_region_scanning();
2932 
2933   print_heap_before_gc();
2934   print_heap_regions();
2935   trace_heap_before_gc(_gc_tracer_stw);
2936 
2937   _verifier->verify_region_sets_optional();
2938   _verifier->verify_dirty_young_regions();
2939 
2940   // We should not be doing concurrent start unless the concurrent mark thread is running
2941   if (!_cm_thread->should_terminate()) {
2942     // This call will decide whether this pause is a concurrent start
2943     // pause. If it is, in_concurrent_start_gc() will return true
2944     // for the duration of this pause.
2945     policy()->decide_on_conc_mark_initiation();
2946   }
2947 
2948   // We do not allow concurrent start to be piggy-backed on a mixed GC.
2949   assert(!collector_state()->in_concurrent_start_gc() ||
2950          collector_state()->in_young_only_phase(), "sanity");
2951   // We also do not allow mixed GCs during marking.
2952   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2953 
2954   // Record whether this pause is a concurrent start. When the current
2955   // thread has completed its logging output and it's safe to signal
2956   // the CM thread, the flag's value in the policy has been reset.
2957   bool should_start_conc_mark = collector_state()->in_concurrent_start_gc();
2958   if (should_start_conc_mark) {
2959     _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2960   }
2961 
2962   // Inner scope for scope based logging, timers, and stats collection
2963   {
2964     G1EvacuationInfo evacuation_info;
2965 
2966     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2967 
2968     GCTraceCPUTime tcpu;
2969 
2970     GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
2971 
2972     uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
2973                                                             workers()->active_workers(),
2974                                                             Threads::number_of_non_daemon_threads());
2975     active_workers = workers()->update_active_workers(active_workers);
2976     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2977 
2978     G1MonitoringScope ms(g1mm(),
2979                          false /* full_gc */,
2980                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2981 
2982     G1HeapTransition heap_transition(this);
2983 
2984     {
2985       IsGCActiveMark x;
2986 
2987       gc_prologue(false);
2988 
2989       G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
2990       verify_before_young_collection(verify_type);
2991 
2992       {
2993         // The elapsed time induced by the start time below deliberately elides
2994         // the possible verification above.
2995         double sample_start_time_sec = os::elapsedTime();
2996 
2997         // Please see comment in g1CollectedHeap.hpp and
2998         // G1CollectedHeap::ref_processing_init() to see how
2999         // reference processing currently works in G1.
3000         _ref_processor_stw->enable_discovery();
3001 
3002         // We want to temporarily turn off discovery by the
3003         // CM ref processor, if necessary, and turn it back on
3004         // on again later if we do. Using a scoped
3005         // NoRefDiscovery object will do this.
3006         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3007 
3008         policy()->record_collection_pause_start(sample_start_time_sec);
3009 
3010         // Forget the current allocation region (we might even choose it to be part
3011         // of the collection set!).
3012         _allocator->release_mutator_alloc_regions();
3013 
3014         calculate_collection_set(evacuation_info, target_pause_time_ms);
3015 
3016         G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3017         G1ParScanThreadStateSet per_thread_states(this,
3018                                                   &rdcqs,
3019                                                   workers()->active_workers(),
3020                                                   collection_set()->young_region_length(),
3021                                                   collection_set()->optional_region_length());
3022         pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3023 
3024         // Actually do the work...
3025         evacuate_initial_collection_set(&per_thread_states);
3026 
3027         if (_collection_set.optional_region_length() != 0) {
3028           evacuate_optional_collection_set(&per_thread_states);
3029         }
3030         post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3031 
3032         start_new_collection_set();
3033 
3034         _survivor_evac_stats.adjust_desired_plab_sz();
3035         _old_evac_stats.adjust_desired_plab_sz();
3036 
3037         if (should_start_conc_mark) {
3038           // We have to do this before we notify the CM threads that
3039           // they can start working to make sure that all the
3040           // appropriate initialization is done on the CM object.
3041           concurrent_mark()->post_concurrent_start();
3042           // Note that we don't actually trigger the CM thread at
3043           // this point. We do that later when we're sure that
3044           // the current thread has completed its logging output.
3045         }
3046 
3047         allocate_dummy_regions();
3048 
3049         _allocator->init_mutator_alloc_regions();
3050 
3051         expand_heap_after_young_collection();
3052 
3053         double sample_end_time_sec = os::elapsedTime();
3054         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3055         policy()->record_collection_pause_end(pause_time_ms);
3056       }
3057 
3058       verify_after_young_collection(verify_type);
3059 
3060       gc_epilogue(false);
3061     }
3062 
3063     // Print the remainder of the GC log output.
3064     if (evacuation_failed()) {
3065       log_info(gc)("To-space exhausted");
3066     }
3067 
3068     policy()->print_phases();
3069     heap_transition.print();
3070 
3071     _hrm->verify_optional();
3072     _verifier->verify_region_sets_optional();
3073 
3074     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3075     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3076 
3077     print_heap_after_gc();
3078     print_heap_regions();
3079     trace_heap_after_gc(_gc_tracer_stw);
3080 
3081     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3082     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3083     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3084     // before any GC notifications are raised.
3085     g1mm()->update_sizes();
3086 
3087     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3088     _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3089     _gc_timer_stw->register_gc_end();
3090     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3091   }
3092   // It should now be safe to tell the concurrent mark thread to start
3093   // without its logging output interfering with the logging output
3094   // that came from the pause.
3095 
3096   if (should_start_conc_mark) {
3097     // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3098     // thread(s) could be running concurrently with us. Make sure that anything
3099     // after this point does not assume that we are the only GC thread running.
3100     // Note: of course, the actual marking work will not start until the safepoint
3101     // itself is released in SuspendibleThreadSet::desynchronize().
3102     do_concurrent_mark();
3103     ConcurrentGCBreakpoints::notify_idle_to_active();
3104   }
3105 }
3106 
3107 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3108   G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3109   workers()->run_task(&rsfp_task);
3110 }
3111 
3112 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3113   double remove_self_forwards_start = os::elapsedTime();
3114 
3115   remove_self_forwarding_pointers(rdcqs);
3116   _preserved_marks_set.restore(workers());
3117 
3118   phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3119 }
3120 
3121 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3122   if (!_evacuation_failed) {
3123     _evacuation_failed = true;
3124   }
3125 
3126   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3127   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3128 }
3129 
3130 bool G1ParEvacuateFollowersClosure::offer_termination() {
3131   EventGCPhaseParallel event;
3132   G1ParScanThreadState* const pss = par_scan_state();
3133   start_term_time();
3134   const bool res = terminator()->offer_termination();
3135   end_term_time();
3136   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3137   return res;
3138 }
3139 
3140 void G1ParEvacuateFollowersClosure::do_void() {
3141   EventGCPhaseParallel event;
3142   G1ParScanThreadState* const pss = par_scan_state();
3143   pss->trim_queue();
3144   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3145   do {
3146     EventGCPhaseParallel event;
3147     pss->steal_and_trim_queue(queues());
3148     event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3149   } while (!offer_termination());
3150 }
3151 
3152 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3153                                         bool class_unloading_occurred) {
3154   uint num_workers = workers()->active_workers();
3155   G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3156   workers()->run_task(&unlink_task);
3157 }
3158 
3159 // Clean string dedup data structures.
3160 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3161 // record the durations of the phases. Hence the almost-copy.
3162 class G1StringDedupCleaningTask : public AbstractGangTask {
3163   BoolObjectClosure* _is_alive;
3164   OopClosure* _keep_alive;
3165   G1GCPhaseTimes* _phase_times;
3166 
3167 public:
3168   G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3169                             OopClosure* keep_alive,
3170                             G1GCPhaseTimes* phase_times) :
3171     AbstractGangTask("Partial Cleaning Task"),
3172     _is_alive(is_alive),
3173     _keep_alive(keep_alive),
3174     _phase_times(phase_times)
3175   {
3176     assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3177     StringDedup::gc_prologue(true);
3178   }
3179 
3180   ~G1StringDedupCleaningTask() {
3181     StringDedup::gc_epilogue();
3182   }
3183 
3184   void work(uint worker_id) {
3185     StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3186     {
3187       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3188       StringDedupQueue::unlink_or_oops_do(&cl);
3189     }
3190     {
3191       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3192       StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3193     }
3194   }
3195 };
3196 
3197 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3198                                             OopClosure* keep_alive,
3199                                             G1GCPhaseTimes* phase_times) {
3200   G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3201   workers()->run_task(&cl);
3202 }
3203 
3204 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3205  private:
3206   G1RedirtyCardsQueueSet* _qset;
3207   G1CollectedHeap* _g1h;
3208   BufferNode* volatile _nodes;
3209 
3210   void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3211     size_t buffer_size = _qset->buffer_size();
3212     BufferNode* next = Atomic::load(&_nodes);
3213     while (next != NULL) {
3214       BufferNode* node = next;
3215       next = Atomic::cmpxchg(&_nodes, node, node->next());
3216       if (next == node) {
3217         cl->apply_to_buffer(node, buffer_size, worker_id);
3218         next = node->next();
3219       }
3220     }
3221   }
3222 
3223  public:
3224   G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3225     AbstractGangTask("Redirty Cards"),
3226     _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3227 
3228   virtual void work(uint worker_id) {
3229     G1GCPhaseTimes* p = _g1h->phase_times();
3230     G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3231 
3232     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3233     par_apply(&cl, worker_id);
3234 
3235     p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3236   }
3237 };
3238 
3239 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3240   double redirty_logged_cards_start = os::elapsedTime();
3241 
3242   G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3243   workers()->run_task(&redirty_task);
3244 
3245   G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3246   dcq.merge_bufferlists(rdcqs);
3247 
3248   phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3249 }
3250 
3251 // Weak Reference Processing support
3252 
3253 bool G1STWIsAliveClosure::do_object_b(oop p) {
3254   // An object is reachable if it is outside the collection set,
3255   // or is inside and copied.
3256   return !_g1h->is_in_cset(p) || p->is_forwarded();
3257 }
3258 
3259 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3260   assert(obj != NULL, "must not be NULL");
3261   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3262   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3263   // may falsely indicate that this is not the case here: however the collection set only
3264   // contains old regions when concurrent mark is not running.
3265   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3266 }
3267 
3268 // Non Copying Keep Alive closure
3269 class G1KeepAliveClosure: public OopClosure {
3270   G1CollectedHeap*_g1h;
3271 public:
3272   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3273   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3274   void do_oop(oop* p) {
3275     oop obj = *p;
3276     assert(obj != NULL, "the caller should have filtered out NULL values");
3277 
3278     const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3279     if (!region_attr.is_in_cset_or_humongous()) {
3280       return;
3281     }
3282     if (region_attr.is_in_cset()) {
3283       assert( obj->is_forwarded(), "invariant" );
3284       *p = obj->forwardee();
3285     } else {
3286       assert(!obj->is_forwarded(), "invariant" );
3287       assert(region_attr.is_humongous(),
3288              "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3289      _g1h->set_humongous_is_live(obj);
3290     }
3291   }
3292 };
3293 
3294 // Copying Keep Alive closure - can be called from both
3295 // serial and parallel code as long as different worker
3296 // threads utilize different G1ParScanThreadState instances
3297 // and different queues.
3298 
3299 class G1CopyingKeepAliveClosure: public OopClosure {
3300   G1CollectedHeap*         _g1h;
3301   G1ParScanThreadState*    _par_scan_state;
3302 
3303 public:
3304   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3305                             G1ParScanThreadState* pss):
3306     _g1h(g1h),
3307     _par_scan_state(pss)
3308   {}
3309 
3310   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3311   virtual void do_oop(      oop* p) { do_oop_work(p); }
3312 
3313   template <class T> void do_oop_work(T* p) {
3314     oop obj = RawAccess<>::oop_load(p);
3315 
3316     if (_g1h->is_in_cset_or_humongous(obj)) {
3317       // If the referent object has been forwarded (either copied
3318       // to a new location or to itself in the event of an
3319       // evacuation failure) then we need to update the reference
3320       // field and, if both reference and referent are in the G1
3321       // heap, update the RSet for the referent.
3322       //
3323       // If the referent has not been forwarded then we have to keep
3324       // it alive by policy. Therefore we have copy the referent.
3325       //
3326       // When the queue is drained (after each phase of reference processing)
3327       // the object and it's followers will be copied, the reference field set
3328       // to point to the new location, and the RSet updated.
3329       _par_scan_state->push_on_queue(ScannerTask(p));
3330     }
3331   }
3332 };
3333 
3334 // Serial drain queue closure. Called as the 'complete_gc'
3335 // closure for each discovered list in some of the
3336 // reference processing phases.
3337 
3338 class G1STWDrainQueueClosure: public VoidClosure {
3339 protected:
3340   G1CollectedHeap* _g1h;
3341   G1ParScanThreadState* _par_scan_state;
3342 
3343   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3344 
3345 public:
3346   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3347     _g1h(g1h),
3348     _par_scan_state(pss)
3349   { }
3350 
3351   void do_void() {
3352     G1ParScanThreadState* const pss = par_scan_state();
3353     pss->trim_queue();
3354   }
3355 };
3356 
3357 // Parallel Reference Processing closures
3358 
3359 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3360 // processing during G1 evacuation pauses.
3361 
3362 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3363 private:
3364   G1CollectedHeap*          _g1h;
3365   G1ParScanThreadStateSet*  _pss;
3366   G1ScannerTasksQueueSet*   _queues;
3367   WorkGang*                 _workers;
3368 
3369 public:
3370   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3371                            G1ParScanThreadStateSet* per_thread_states,
3372                            WorkGang* workers,
3373                            G1ScannerTasksQueueSet *task_queues) :
3374     _g1h(g1h),
3375     _pss(per_thread_states),
3376     _queues(task_queues),
3377     _workers(workers)
3378   {
3379     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3380   }
3381 
3382   // Executes the given task using concurrent marking worker threads.
3383   virtual void execute(ProcessTask& task, uint ergo_workers);
3384 };
3385 
3386 // Gang task for possibly parallel reference processing
3387 
3388 class G1STWRefProcTaskProxy: public AbstractGangTask {
3389   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3390   ProcessTask&     _proc_task;
3391   G1CollectedHeap* _g1h;
3392   G1ParScanThreadStateSet* _pss;
3393   G1ScannerTasksQueueSet* _task_queues;
3394   TaskTerminator* _terminator;
3395 
3396 public:
3397   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3398                         G1CollectedHeap* g1h,
3399                         G1ParScanThreadStateSet* per_thread_states,
3400                         G1ScannerTasksQueueSet *task_queues,
3401                         TaskTerminator* terminator) :
3402     AbstractGangTask("Process reference objects in parallel"),
3403     _proc_task(proc_task),
3404     _g1h(g1h),
3405     _pss(per_thread_states),
3406     _task_queues(task_queues),
3407     _terminator(terminator)
3408   {}
3409 
3410   virtual void work(uint worker_id) {
3411     // The reference processing task executed by a single worker.
3412     ResourceMark rm;
3413 
3414     G1STWIsAliveClosure is_alive(_g1h);
3415 
3416     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3417     pss->set_ref_discoverer(NULL);
3418 
3419     // Keep alive closure.
3420     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3421 
3422     // Complete GC closure
3423     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3424 
3425     // Call the reference processing task's work routine.
3426     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3427 
3428     // Note we cannot assert that the refs array is empty here as not all
3429     // of the processing tasks (specifically phase2 - pp2_work) execute
3430     // the complete_gc closure (which ordinarily would drain the queue) so
3431     // the queue may not be empty.
3432   }
3433 };
3434 
3435 // Driver routine for parallel reference processing.
3436 // Creates an instance of the ref processing gang
3437 // task and has the worker threads execute it.
3438 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3439   assert(_workers != NULL, "Need parallel worker threads.");
3440 
3441   assert(_workers->active_workers() >= ergo_workers,
3442          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3443          ergo_workers, _workers->active_workers());
3444   TaskTerminator terminator(ergo_workers, _queues);
3445   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3446 
3447   _workers->run_task(&proc_task_proxy, ergo_workers);
3448 }
3449 
3450 // End of weak reference support closures
3451 
3452 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3453   double ref_proc_start = os::elapsedTime();
3454 
3455   ReferenceProcessor* rp = _ref_processor_stw;
3456   assert(rp->discovery_enabled(), "should have been enabled");
3457 
3458   // Closure to test whether a referent is alive.
3459   G1STWIsAliveClosure is_alive(this);
3460 
3461   // Even when parallel reference processing is enabled, the processing
3462   // of JNI refs is serial and performed serially by the current thread
3463   // rather than by a worker. The following PSS will be used for processing
3464   // JNI refs.
3465 
3466   // Use only a single queue for this PSS.
3467   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3468   pss->set_ref_discoverer(NULL);
3469   assert(pss->queue_is_empty(), "pre-condition");
3470 
3471   // Keep alive closure.
3472   G1CopyingKeepAliveClosure keep_alive(this, pss);
3473 
3474   // Serial Complete GC closure
3475   G1STWDrainQueueClosure drain_queue(this, pss);
3476 
3477   // Setup the soft refs policy...
3478   rp->setup_policy(false);
3479 
3480   ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3481 
3482   ReferenceProcessorStats stats;
3483   if (!rp->processing_is_mt()) {
3484     // Serial reference processing...
3485     stats = rp->process_discovered_references(&is_alive,
3486                                               &keep_alive,
3487                                               &drain_queue,
3488                                               NULL,
3489                                               pt);
3490   } else {
3491     uint no_of_gc_workers = workers()->active_workers();
3492 
3493     // Parallel reference processing
3494     assert(no_of_gc_workers <= rp->max_num_queues(),
3495            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3496            no_of_gc_workers,  rp->max_num_queues());
3497 
3498     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3499     stats = rp->process_discovered_references(&is_alive,
3500                                               &keep_alive,
3501                                               &drain_queue,
3502                                               &par_task_executor,
3503                                               pt);
3504   }
3505 
3506   _gc_tracer_stw->report_gc_reference_stats(stats);
3507 
3508   // We have completed copying any necessary live referent objects.
3509   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3510 
3511   make_pending_list_reachable();
3512 
3513   assert(!rp->discovery_enabled(), "Postcondition");
3514   rp->verify_no_references_recorded();
3515 
3516   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3517   phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3518 }
3519 
3520 void G1CollectedHeap::make_pending_list_reachable() {
3521   if (collector_state()->in_concurrent_start_gc()) {
3522     oop pll_head = Universe::reference_pending_list();
3523     if (pll_head != NULL) {
3524       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3525       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3526     }
3527   }
3528 }
3529 
3530 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3531   Ticks start = Ticks::now();
3532   per_thread_states->flush();
3533   phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3534 }
3535 
3536 class G1PrepareEvacuationTask : public AbstractGangTask {
3537   class G1PrepareRegionsClosure : public HeapRegionClosure {
3538     G1CollectedHeap* _g1h;
3539     G1PrepareEvacuationTask* _parent_task;
3540     size_t _worker_humongous_total;
3541     size_t _worker_humongous_candidates;
3542 
3543     bool humongous_region_is_candidate(HeapRegion* region) const {
3544       assert(region->is_starts_humongous(), "Must start a humongous object");
3545 
3546       oop obj = oop(region->bottom());
3547 
3548       // Dead objects cannot be eager reclaim candidates. Due to class
3549       // unloading it is unsafe to query their classes so we return early.
3550       if (_g1h->is_obj_dead(obj, region)) {
3551         return false;
3552       }
3553 
3554       // If we do not have a complete remembered set for the region, then we can
3555       // not be sure that we have all references to it.
3556       if (!region->rem_set()->is_complete()) {
3557         return false;
3558       }
3559       // Candidate selection must satisfy the following constraints
3560       // while concurrent marking is in progress:
3561       //
3562       // * In order to maintain SATB invariants, an object must not be
3563       // reclaimed if it was allocated before the start of marking and
3564       // has not had its references scanned.  Such an object must have
3565       // its references (including type metadata) scanned to ensure no
3566       // live objects are missed by the marking process.  Objects
3567       // allocated after the start of concurrent marking don't need to
3568       // be scanned.
3569       //
3570       // * An object must not be reclaimed if it is on the concurrent
3571       // mark stack.  Objects allocated after the start of concurrent
3572       // marking are never pushed on the mark stack.
3573       //
3574       // Nominating only objects allocated after the start of concurrent
3575       // marking is sufficient to meet both constraints.  This may miss
3576       // some objects that satisfy the constraints, but the marking data
3577       // structures don't support efficiently performing the needed
3578       // additional tests or scrubbing of the mark stack.
3579       //
3580       // However, we presently only nominate is_typeArray() objects.
3581       // A humongous object containing references induces remembered
3582       // set entries on other regions.  In order to reclaim such an
3583       // object, those remembered sets would need to be cleaned up.
3584       //
3585       // We also treat is_typeArray() objects specially, allowing them
3586       // to be reclaimed even if allocated before the start of
3587       // concurrent mark.  For this we rely on mark stack insertion to
3588       // exclude is_typeArray() objects, preventing reclaiming an object
3589       // that is in the mark stack.  We also rely on the metadata for
3590       // such objects to be built-in and so ensured to be kept live.
3591       // Frequent allocation and drop of large binary blobs is an
3592       // important use case for eager reclaim, and this special handling
3593       // may reduce needed headroom.
3594 
3595       return obj->is_typeArray() &&
3596              _g1h->is_potential_eager_reclaim_candidate(region);
3597     }
3598 
3599   public:
3600     G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3601       _g1h(g1h),
3602       _parent_task(parent_task),
3603       _worker_humongous_total(0),
3604       _worker_humongous_candidates(0) { }
3605 
3606     ~G1PrepareRegionsClosure() {
3607       _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3608       _parent_task->add_humongous_total(_worker_humongous_total);
3609     }
3610 
3611     virtual bool do_heap_region(HeapRegion* hr) {
3612       // First prepare the region for scanning
3613       _g1h->rem_set()->prepare_region_for_scan(hr);
3614 
3615       // Now check if region is a humongous candidate
3616       if (!hr->is_starts_humongous()) {
3617         _g1h->register_region_with_region_attr(hr);
3618         return false;
3619       }
3620 
3621       uint index = hr->hrm_index();
3622       if (humongous_region_is_candidate(hr)) {
3623         _g1h->set_humongous_reclaim_candidate(index, true);
3624         _g1h->register_humongous_region_with_region_attr(index);
3625         _worker_humongous_candidates++;
3626         // We will later handle the remembered sets of these regions.
3627       } else {
3628         _g1h->set_humongous_reclaim_candidate(index, false);
3629         _g1h->register_region_with_region_attr(hr);
3630       }
3631       _worker_humongous_total++;
3632 
3633       return false;
3634     }
3635   };
3636 
3637   G1CollectedHeap* _g1h;
3638   HeapRegionClaimer _claimer;
3639   volatile size_t _humongous_total;
3640   volatile size_t _humongous_candidates;
3641 public:
3642   G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3643     AbstractGangTask("Prepare Evacuation"),
3644     _g1h(g1h),
3645     _claimer(_g1h->workers()->active_workers()),
3646     _humongous_total(0),
3647     _humongous_candidates(0) { }
3648 
3649   ~G1PrepareEvacuationTask() {
3650     _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3651   }
3652 
3653   void work(uint worker_id) {
3654     G1PrepareRegionsClosure cl(_g1h, this);
3655     _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3656   }
3657 
3658   void add_humongous_candidates(size_t candidates) {
3659     Atomic::add(&_humongous_candidates, candidates);
3660   }
3661 
3662   void add_humongous_total(size_t total) {
3663     Atomic::add(&_humongous_total, total);
3664   }
3665 
3666   size_t humongous_candidates() {
3667     return _humongous_candidates;
3668   }
3669 
3670   size_t humongous_total() {
3671     return _humongous_total;
3672   }
3673 };
3674 
3675 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3676   _bytes_used_during_gc = 0;
3677 
3678   _expand_heap_after_alloc_failure = true;
3679   _evacuation_failed = false;
3680 
3681   // Disable the hot card cache.
3682   _hot_card_cache->reset_hot_cache_claimed_index();
3683   _hot_card_cache->set_use_cache(false);
3684 
3685   // Initialize the GC alloc regions.
3686   _allocator->init_gc_alloc_regions(evacuation_info);
3687 
3688   {
3689     Ticks start = Ticks::now();
3690     rem_set()->prepare_for_scan_heap_roots();
3691     phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3692   }
3693 
3694   {
3695     G1PrepareEvacuationTask g1_prep_task(this);
3696     Tickspan task_time = run_task(&g1_prep_task);
3697 
3698     phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3699                                            g1_prep_task.humongous_total(),
3700                                            g1_prep_task.humongous_candidates());
3701   }
3702 
3703   assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3704   _preserved_marks_set.assert_empty();
3705 
3706 #if COMPILER2_OR_JVMCI
3707   DerivedPointerTable::clear();
3708 #endif
3709 
3710   // Concurrent start needs claim bits to keep track of the marked-through CLDs.
3711   if (collector_state()->in_concurrent_start_gc()) {
3712     concurrent_mark()->pre_concurrent_start();
3713 
3714     double start_clear_claimed_marks = os::elapsedTime();
3715 
3716     ClassLoaderDataGraph::clear_claimed_marks();
3717 
3718     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3719     phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3720   }
3721 
3722   // Should G1EvacuationFailureALot be in effect for this GC?
3723   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3724 }
3725 
3726 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3727 protected:
3728   G1CollectedHeap* _g1h;
3729   G1ParScanThreadStateSet* _per_thread_states;
3730   G1ScannerTasksQueueSet* _task_queues;
3731   TaskTerminator _terminator;
3732   uint _num_workers;
3733 
3734   void evacuate_live_objects(G1ParScanThreadState* pss,
3735                              uint worker_id,
3736                              G1GCPhaseTimes::GCParPhases objcopy_phase,
3737                              G1GCPhaseTimes::GCParPhases termination_phase) {
3738     G1GCPhaseTimes* p = _g1h->phase_times();
3739 
3740     Ticks start = Ticks::now();
3741     G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3742     cl.do_void();
3743 
3744     assert(pss->queue_is_empty(), "should be empty");
3745 
3746     Tickspan evac_time = (Ticks::now() - start);
3747     p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3748 
3749     if (termination_phase == G1GCPhaseTimes::Termination) {
3750       p->record_time_secs(termination_phase, worker_id, cl.term_time());
3751       p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3752     } else {
3753       p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3754       p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3755     }
3756     assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3757   }
3758 
3759   virtual void start_work(uint worker_id) { }
3760 
3761   virtual void end_work(uint worker_id) { }
3762 
3763   virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3764 
3765   virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3766 
3767 public:
3768   G1EvacuateRegionsBaseTask(const char* name,
3769                             G1ParScanThreadStateSet* per_thread_states,
3770                             G1ScannerTasksQueueSet* task_queues,
3771                             uint num_workers) :
3772     AbstractGangTask(name),
3773     _g1h(G1CollectedHeap::heap()),
3774     _per_thread_states(per_thread_states),
3775     _task_queues(task_queues),
3776     _terminator(num_workers, _task_queues),
3777     _num_workers(num_workers)
3778   { }
3779 
3780   void work(uint worker_id) {
3781     start_work(worker_id);
3782 
3783     {
3784       ResourceMark rm;
3785 
3786       G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3787       pss->set_ref_discoverer(_g1h->ref_processor_stw());
3788 
3789       scan_roots(pss, worker_id);
3790       evacuate_live_objects(pss, worker_id);
3791     }
3792 
3793     end_work(worker_id);
3794   }
3795 };
3796 
3797 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3798   G1RootProcessor* _root_processor;
3799 
3800   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3801     _root_processor->evacuate_roots(pss, worker_id);
3802     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3803     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3804   }
3805 
3806   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3807     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3808   }
3809 
3810   void start_work(uint worker_id) {
3811     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3812   }
3813 
3814   void end_work(uint worker_id) {
3815     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3816   }
3817 
3818 public:
3819   G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3820                         G1ParScanThreadStateSet* per_thread_states,
3821                         G1ScannerTasksQueueSet* task_queues,
3822                         G1RootProcessor* root_processor,
3823                         uint num_workers) :
3824     G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3825     _root_processor(root_processor)
3826   { }
3827 };
3828 
3829 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3830   G1GCPhaseTimes* p = phase_times();
3831 
3832   {
3833     Ticks start = Ticks::now();
3834     rem_set()->merge_heap_roots(true /* initial_evacuation */);
3835     p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3836   }
3837 
3838   Tickspan task_time;
3839   const uint num_workers = workers()->active_workers();
3840 
3841   Ticks start_processing = Ticks::now();
3842   {
3843     G1RootProcessor root_processor(this, num_workers);
3844     G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3845     task_time = run_task(&g1_par_task);
3846     // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3847     // To extract its code root fixup time we measure total time of this scope and
3848     // subtract from the time the WorkGang task took.
3849   }
3850   Tickspan total_processing = Ticks::now() - start_processing;
3851 
3852   p->record_initial_evac_time(task_time.seconds() * 1000.0);
3853   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3854 }
3855 
3856 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3857 
3858   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3859     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3860     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3861   }
3862 
3863   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3864     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3865   }
3866 
3867 public:
3868   G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3869                                 G1ScannerTasksQueueSet* queues,
3870                                 uint num_workers) :
3871     G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3872   }
3873 };
3874 
3875 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3876   class G1MarkScope : public MarkScope { };
3877 
3878   Tickspan task_time;
3879 
3880   Ticks start_processing = Ticks::now();
3881   {
3882     G1MarkScope code_mark_scope;
3883     G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3884     task_time = run_task(&task);
3885     // See comment in evacuate_collection_set() for the reason of the scope.
3886   }
3887   Tickspan total_processing = Ticks::now() - start_processing;
3888 
3889   G1GCPhaseTimes* p = phase_times();
3890   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3891 }
3892 
3893 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3894   const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3895 
3896   while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3897 
3898     double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3899     double time_left_ms = MaxGCPauseMillis - time_used_ms;
3900 
3901     if (time_left_ms < 0 ||
3902         !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3903       log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3904                                 _collection_set.optional_region_length(), time_left_ms);
3905       break;
3906     }
3907 
3908     {
3909       Ticks start = Ticks::now();
3910       rem_set()->merge_heap_roots(false /* initial_evacuation */);
3911       phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3912     }
3913 
3914     {
3915       Ticks start = Ticks::now();
3916       evacuate_next_optional_regions(per_thread_states);
3917       phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3918     }
3919   }
3920 
3921   _collection_set.abandon_optional_collection_set(per_thread_states);
3922 }
3923 
3924 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3925                                                    G1RedirtyCardsQueueSet* rdcqs,
3926                                                    G1ParScanThreadStateSet* per_thread_states) {
3927   G1GCPhaseTimes* p = phase_times();
3928 
3929   rem_set()->cleanup_after_scan_heap_roots();
3930 
3931   // Process any discovered reference objects - we have
3932   // to do this _before_ we retire the GC alloc regions
3933   // as we may have to copy some 'reachable' referent
3934   // objects (and their reachable sub-graphs) that were
3935   // not copied during the pause.
3936   process_discovered_references(per_thread_states);
3937 
3938   G1STWIsAliveClosure is_alive(this);
3939   G1KeepAliveClosure keep_alive(this);
3940 
3941   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
3942 
3943   if (G1StringDedup::is_enabled()) {
3944     double string_dedup_time_ms = os::elapsedTime();
3945 
3946     string_dedup_cleaning(&is_alive, &keep_alive, p);
3947 
3948     double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3949     p->record_string_deduplication_time(string_cleanup_time_ms);
3950   }
3951 
3952   _allocator->release_gc_alloc_regions(evacuation_info);
3953 
3954   if (evacuation_failed()) {
3955     restore_after_evac_failure(rdcqs);
3956 
3957     // Reset the G1EvacuationFailureALot counters and flags
3958     NOT_PRODUCT(reset_evacuation_should_fail();)
3959 
3960     double recalculate_used_start = os::elapsedTime();
3961     set_used(recalculate_used());
3962     p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3963 
3964     if (_archive_allocator != NULL) {
3965       _archive_allocator->clear_used();
3966     }
3967     for (uint i = 0; i < ParallelGCThreads; i++) {
3968       if (_evacuation_failed_info_array[i].has_failed()) {
3969         _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3970       }
3971     }
3972   } else {
3973     // The "used" of the the collection set have already been subtracted
3974     // when they were freed.  Add in the bytes used.
3975     increase_used(_bytes_used_during_gc);
3976   }
3977 
3978   _preserved_marks_set.assert_empty();
3979 
3980   merge_per_thread_state_info(per_thread_states);
3981 
3982   // Reset and re-enable the hot card cache.
3983   // Note the counts for the cards in the regions in the
3984   // collection set are reset when the collection set is freed.
3985   _hot_card_cache->reset_hot_cache();
3986   _hot_card_cache->set_use_cache(true);
3987 
3988   purge_code_root_memory();
3989 
3990   redirty_logged_cards(rdcqs);
3991 
3992   free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3993 
3994   eagerly_reclaim_humongous_regions();
3995 
3996   record_obj_copy_mem_stats();
3997 
3998   evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3999   evacuation_info.set_bytes_used(_bytes_used_during_gc);
4000 
4001 #if COMPILER2_OR_JVMCI
4002   double start = os::elapsedTime();
4003   DerivedPointerTable::update_pointers();
4004   phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4005 #endif
4006   policy()->print_age_table();
4007 }
4008 
4009 void G1CollectedHeap::record_obj_copy_mem_stats() {
4010   policy()->old_gen_alloc_tracker()->
4011     add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4012 
4013   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4014                                                create_g1_evac_summary(&_old_evac_stats));
4015 }
4016 
4017 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4018   assert(!hr->is_free(), "the region should not be free");
4019   assert(!hr->is_empty(), "the region should not be empty");
4020   assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4021 
4022   if (G1VerifyBitmaps) {
4023     MemRegion mr(hr->bottom(), hr->end());
4024     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4025   }
4026 
4027   // Clear the card counts for this region.
4028   // Note: we only need to do this if the region is not young
4029   // (since we don't refine cards in young regions).
4030   if (!hr->is_young()) {
4031     _hot_card_cache->reset_card_counts(hr);
4032   }
4033 
4034   // Reset region metadata to allow reuse.
4035   hr->hr_clear(true /* clear_space */);
4036   _policy->remset_tracker()->update_at_free(hr);
4037 
4038   if (free_list != NULL) {
4039     free_list->add_ordered(hr);
4040   }
4041 }
4042 
4043 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4044                                             FreeRegionList* free_list) {
4045   assert(hr->is_humongous(), "this is only for humongous regions");
4046   assert(free_list != NULL, "pre-condition");
4047   hr->clear_humongous();
4048   free_region(hr, free_list);
4049 }
4050 
4051 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4052                                            const uint humongous_regions_removed) {
4053   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4054     MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4055     _old_set.bulk_remove(old_regions_removed);
4056     _humongous_set.bulk_remove(humongous_regions_removed);
4057   }
4058 
4059 }
4060 
4061 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4062   assert(list != NULL, "list can't be null");
4063   if (!list->is_empty()) {
4064     MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4065     _hrm->insert_list_into_free_list(list);
4066   }
4067 }
4068 
4069 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4070   decrease_used(bytes);
4071 }
4072 
4073 class G1FreeCollectionSetTask : public AbstractGangTask {
4074   // Helper class to keep statistics for the collection set freeing
4075   class FreeCSetStats {
4076     size_t _before_used_bytes;   // Usage in regions successfully evacutate
4077     size_t _after_used_bytes;    // Usage in regions failing evacuation
4078     size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4079     size_t _failure_used_words;  // Live size in failed regions
4080     size_t _failure_waste_words; // Wasted size in failed regions
4081     size_t _rs_length;           // Remembered set size
4082     uint _regions_freed;         // Number of regions freed
4083   public:
4084     FreeCSetStats() :
4085         _before_used_bytes(0),
4086         _after_used_bytes(0),
4087         _bytes_allocated_in_old_since_last_gc(0),
4088         _failure_used_words(0),
4089         _failure_waste_words(0),
4090         _rs_length(0),
4091         _regions_freed(0) { }
4092 
4093     void merge_stats(FreeCSetStats* other) {
4094       assert(other != NULL, "invariant");
4095       _before_used_bytes += other->_before_used_bytes;
4096       _after_used_bytes += other->_after_used_bytes;
4097       _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4098       _failure_used_words += other->_failure_used_words;
4099       _failure_waste_words += other->_failure_waste_words;
4100       _rs_length += other->_rs_length;
4101       _regions_freed += other->_regions_freed;
4102     }
4103 
4104     void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4105       evacuation_info->set_regions_freed(_regions_freed);
4106       evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4107 
4108       g1h->decrement_summary_bytes(_before_used_bytes);
4109       g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4110 
4111       G1Policy *policy = g1h->policy();
4112       policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4113       policy->record_rs_length(_rs_length);
4114       policy->cset_regions_freed();
4115     }
4116 
4117     void account_failed_region(HeapRegion* r) {
4118       size_t used_words = r->marked_bytes() / HeapWordSize;
4119       _failure_used_words += used_words;
4120       _failure_waste_words += HeapRegion::GrainWords - used_words;
4121       _after_used_bytes += r->used();
4122 
4123       // When moving a young gen region to old gen, we "allocate" that whole
4124       // region there. This is in addition to any already evacuated objects.
4125       // Notify the policy about that. Old gen regions do not cause an
4126       // additional allocation: both the objects still in the region and the
4127       // ones already moved are accounted for elsewhere.
4128       if (r->is_young()) {
4129         _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4130       }
4131     }
4132 
4133     void account_evacuated_region(HeapRegion* r) {
4134       _before_used_bytes += r->used();
4135       _regions_freed += 1;
4136     }
4137 
4138     void account_rs_length(HeapRegion* r) {
4139       _rs_length += r->rem_set()->occupied();
4140     }
4141   };
4142 
4143   // Closure applied to all regions in the collection set.
4144   class FreeCSetClosure : public HeapRegionClosure {
4145     // Helper to send JFR events for regions.
4146     class JFREventForRegion {
4147       EventGCPhaseParallel _event;
4148     public:
4149       JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4150         _event.set_gcId(GCId::current());
4151         _event.set_gcWorkerId(worker_id);
4152         if (region->is_young()) {
4153           _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4154         } else {
4155           _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4156         }
4157       }
4158 
4159       ~JFREventForRegion() {
4160         _event.commit();
4161       }
4162     };
4163 
4164     // Helper to do timing for region work.
4165     class TimerForRegion {
4166       Tickspan& _time;
4167       Ticks     _start_time;
4168     public:
4169       TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4170       ~TimerForRegion() {
4171         _time += Ticks::now() - _start_time;
4172       }
4173     };
4174 
4175     // FreeCSetClosure members
4176     G1CollectedHeap* _g1h;
4177     const size_t*    _surviving_young_words;
4178     uint             _worker_id;
4179     Tickspan         _young_time;
4180     Tickspan         _non_young_time;
4181     FreeCSetStats*   _stats;
4182 
4183     void assert_in_cset(HeapRegion* r) {
4184       assert(r->young_index_in_cset() != 0 &&
4185              (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4186              "Young index %u is wrong for region %u of type %s with %u young regions",
4187              r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4188     }
4189 
4190     void handle_evacuated_region(HeapRegion* r) {
4191       assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4192       stats()->account_evacuated_region(r);
4193 
4194       // Free the region and and its remembered set.
4195       _g1h->free_region(r, NULL);
4196     }
4197 
4198     void handle_failed_region(HeapRegion* r) {
4199       // Do some allocation statistics accounting. Regions that failed evacuation
4200       // are always made old, so there is no need to update anything in the young
4201       // gen statistics, but we need to update old gen statistics.
4202       stats()->account_failed_region(r);
4203 
4204       // Update the region state due to the failed evacuation.
4205       r->handle_evacuation_failure();
4206 
4207       // Add region to old set, need to hold lock.
4208       MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4209       _g1h->old_set_add(r);
4210     }
4211 
4212     Tickspan& timer_for_region(HeapRegion* r) {
4213       return r->is_young() ? _young_time : _non_young_time;
4214     }
4215 
4216     FreeCSetStats* stats() {
4217       return _stats;
4218     }
4219   public:
4220     FreeCSetClosure(const size_t* surviving_young_words,
4221                     uint worker_id,
4222                     FreeCSetStats* stats) :
4223         HeapRegionClosure(),
4224         _g1h(G1CollectedHeap::heap()),
4225         _surviving_young_words(surviving_young_words),
4226         _worker_id(worker_id),
4227         _young_time(),
4228         _non_young_time(),
4229         _stats(stats) { }
4230 
4231     virtual bool do_heap_region(HeapRegion* r) {
4232       assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4233       JFREventForRegion event(r, _worker_id);
4234       TimerForRegion timer(timer_for_region(r));
4235 
4236       _g1h->clear_region_attr(r);
4237       stats()->account_rs_length(r);
4238 
4239       if (r->is_young()) {
4240         assert_in_cset(r);
4241         r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4242       }
4243 
4244       if (r->evacuation_failed()) {
4245         handle_failed_region(r);
4246       } else {
4247         handle_evacuated_region(r);
4248       }
4249       assert(!_g1h->is_on_master_free_list(r), "sanity");
4250 
4251       return false;
4252     }
4253 
4254     void report_timing(Tickspan parallel_time) {
4255       G1GCPhaseTimes* pt = _g1h->phase_times();
4256       pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4257       if (_young_time.value() > 0) {
4258         pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4259       }
4260       if (_non_young_time.value() > 0) {
4261         pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4262       }
4263     }
4264   };
4265 
4266   // G1FreeCollectionSetTask members
4267   G1CollectedHeap*  _g1h;
4268   G1EvacuationInfo* _evacuation_info;
4269   FreeCSetStats*    _worker_stats;
4270   HeapRegionClaimer _claimer;
4271   const size_t*     _surviving_young_words;
4272   uint              _active_workers;
4273 
4274   FreeCSetStats* worker_stats(uint worker) {
4275     return &_worker_stats[worker];
4276   }
4277 
4278   void report_statistics() {
4279     // Merge the accounting
4280     FreeCSetStats total_stats;
4281     for (uint worker = 0; worker < _active_workers; worker++) {
4282       total_stats.merge_stats(worker_stats(worker));
4283     }
4284     total_stats.report(_g1h, _evacuation_info);
4285   }
4286 
4287 public:
4288   G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4289       AbstractGangTask("G1 Free Collection Set"),
4290       _g1h(G1CollectedHeap::heap()),
4291       _evacuation_info(evacuation_info),
4292       _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4293       _claimer(active_workers),
4294       _surviving_young_words(surviving_young_words),
4295       _active_workers(active_workers) {
4296     for (uint worker = 0; worker < active_workers; worker++) {
4297       ::new (&_worker_stats[worker]) FreeCSetStats();
4298     }
4299   }
4300 
4301   ~G1FreeCollectionSetTask() {
4302     Ticks serial_time = Ticks::now();
4303     report_statistics();
4304     for (uint worker = 0; worker < _active_workers; worker++) {
4305       _worker_stats[worker].~FreeCSetStats();
4306     }
4307     FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4308     _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4309   }
4310 
4311   virtual void work(uint worker_id) {
4312     EventGCPhaseParallel event;
4313     Ticks start = Ticks::now();
4314     FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4315     _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4316 
4317     // Report the total parallel time along with some more detailed metrics.
4318     cl.report_timing(Ticks::now() - start);
4319     event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4320   }
4321 };
4322 
4323 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4324   _eden.clear();
4325 
4326   // The free collections set is split up in two tasks, the first
4327   // frees the collection set and records what regions are free,
4328   // and the second one rebuilds the free list. This proved to be
4329   // more efficient than adding a sorted list to another.
4330 
4331   Ticks free_cset_start_time = Ticks::now();
4332   {
4333     uint const num_cs_regions = _collection_set.region_length();
4334     uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4335     G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4336 
4337     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4338                         cl.name(), num_workers, num_cs_regions, num_regions());
4339     workers()->run_task(&cl, num_workers);
4340   }
4341 
4342   Ticks free_cset_end_time = Ticks::now();
4343   phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4344 
4345   // Now rebuild the free region list.
4346   hrm()->rebuild_free_list(workers());
4347   phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4348 
4349   collection_set->clear();
4350 }
4351 
4352 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4353  private:
4354   FreeRegionList* _free_region_list;
4355   HeapRegionSet* _proxy_set;
4356   uint _humongous_objects_reclaimed;
4357   uint _humongous_regions_reclaimed;
4358   size_t _freed_bytes;
4359  public:
4360 
4361   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4362     _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4363   }
4364 
4365   virtual bool do_heap_region(HeapRegion* r) {
4366     if (!r->is_starts_humongous()) {
4367       return false;
4368     }
4369 
4370     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4371 
4372     oop obj = (oop)r->bottom();
4373     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4374 
4375     // The following checks whether the humongous object is live are sufficient.
4376     // The main additional check (in addition to having a reference from the roots
4377     // or the young gen) is whether the humongous object has a remembered set entry.
4378     //
4379     // A humongous object cannot be live if there is no remembered set for it
4380     // because:
4381     // - there can be no references from within humongous starts regions referencing
4382     // the object because we never allocate other objects into them.
4383     // (I.e. there are no intra-region references that may be missed by the
4384     // remembered set)
4385     // - as soon there is a remembered set entry to the humongous starts region
4386     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4387     // until the end of a concurrent mark.
4388     //
4389     // It is not required to check whether the object has been found dead by marking
4390     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4391     // all objects allocated during that time are considered live.
4392     // SATB marking is even more conservative than the remembered set.
4393     // So if at this point in the collection there is no remembered set entry,
4394     // nobody has a reference to it.
4395     // At the start of collection we flush all refinement logs, and remembered sets
4396     // are completely up-to-date wrt to references to the humongous object.
4397     //
4398     // Other implementation considerations:
4399     // - never consider object arrays at this time because they would pose
4400     // considerable effort for cleaning up the the remembered sets. This is
4401     // required because stale remembered sets might reference locations that
4402     // are currently allocated into.
4403     uint region_idx = r->hrm_index();
4404     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4405         !r->rem_set()->is_empty()) {
4406       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",
4407                                region_idx,
4408                                (size_t)obj->size() * HeapWordSize,
4409                                p2i(r->bottom()),
4410                                r->rem_set()->occupied(),
4411                                r->rem_set()->strong_code_roots_list_length(),
4412                                next_bitmap->is_marked(r->bottom()),
4413                                g1h->is_humongous_reclaim_candidate(region_idx),
4414                                obj->is_typeArray()
4415                               );
4416       return false;
4417     }
4418 
4419     guarantee(obj->is_typeArray(),
4420               "Only eagerly reclaiming type arrays is supported, but the object "
4421               PTR_FORMAT " is not.", p2i(r->bottom()));
4422 
4423     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",
4424                              region_idx,
4425                              (size_t)obj->size() * HeapWordSize,
4426                              p2i(r->bottom()),
4427                              r->rem_set()->occupied(),
4428                              r->rem_set()->strong_code_roots_list_length(),
4429                              next_bitmap->is_marked(r->bottom()),
4430                              g1h->is_humongous_reclaim_candidate(region_idx),
4431                              obj->is_typeArray()
4432                             );
4433 
4434     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4435     cm->humongous_object_eagerly_reclaimed(r);
4436     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4437            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4438            region_idx,
4439            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4440            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4441     _humongous_objects_reclaimed++;
4442     do {
4443       HeapRegion* next = g1h->next_region_in_humongous(r);
4444       _freed_bytes += r->used();
4445       r->set_containing_set(NULL);
4446       _humongous_regions_reclaimed++;
4447       g1h->free_humongous_region(r, _free_region_list);
4448       r = next;
4449     } while (r != NULL);
4450 
4451     return false;
4452   }
4453 
4454   uint humongous_objects_reclaimed() {
4455     return _humongous_objects_reclaimed;
4456   }
4457 
4458   uint humongous_regions_reclaimed() {
4459     return _humongous_regions_reclaimed;
4460   }
4461 
4462   size_t bytes_freed() const {
4463     return _freed_bytes;
4464   }
4465 };
4466 
4467 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4468   assert_at_safepoint_on_vm_thread();
4469 
4470   if (!G1EagerReclaimHumongousObjects ||
4471       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4472     phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4473     return;
4474   }
4475 
4476   double start_time = os::elapsedTime();
4477 
4478   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4479 
4480   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4481   heap_region_iterate(&cl);
4482 
4483   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4484 
4485   G1HRPrinter* hrp = hr_printer();
4486   if (hrp->is_active()) {
4487     FreeRegionListIterator iter(&local_cleanup_list);
4488     while (iter.more_available()) {
4489       HeapRegion* hr = iter.get_next();
4490       hrp->cleanup(hr);
4491     }
4492   }
4493 
4494   prepend_to_freelist(&local_cleanup_list);
4495   decrement_summary_bytes(cl.bytes_freed());
4496 
4497   phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4498                                                        cl.humongous_objects_reclaimed());
4499 }
4500 
4501 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4502 public:
4503   virtual bool do_heap_region(HeapRegion* r) {
4504     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4505     G1CollectedHeap::heap()->clear_region_attr(r);
4506     r->clear_young_index_in_cset();
4507     return false;
4508   }
4509 };
4510 
4511 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4512   G1AbandonCollectionSetClosure cl;
4513   collection_set_iterate_all(&cl);
4514 
4515   collection_set->clear();
4516   collection_set->stop_incremental_building();
4517 }
4518 
4519 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4520   return _allocator->is_retained_old_region(hr);
4521 }
4522 
4523 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4524   _eden.add(hr);
4525   _policy->set_region_eden(hr);
4526 }
4527 
4528 #ifdef ASSERT
4529 
4530 class NoYoungRegionsClosure: public HeapRegionClosure {
4531 private:
4532   bool _success;
4533 public:
4534   NoYoungRegionsClosure() : _success(true) { }
4535   bool do_heap_region(HeapRegion* r) {
4536     if (r->is_young()) {
4537       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4538                             p2i(r->bottom()), p2i(r->end()));
4539       _success = false;
4540     }
4541     return false;
4542   }
4543   bool success() { return _success; }
4544 };
4545 
4546 bool G1CollectedHeap::check_young_list_empty() {
4547   bool ret = (young_regions_count() == 0);
4548 
4549   NoYoungRegionsClosure closure;
4550   heap_region_iterate(&closure);
4551   ret = ret && closure.success();
4552 
4553   return ret;
4554 }
4555 
4556 #endif // ASSERT
4557 
4558 class TearDownRegionSetsClosure : public HeapRegionClosure {
4559   HeapRegionSet *_old_set;
4560 
4561 public:
4562   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4563 
4564   bool do_heap_region(HeapRegion* r) {
4565     if (r->is_old()) {
4566       _old_set->remove(r);
4567     } else if(r->is_young()) {
4568       r->uninstall_surv_rate_group();
4569     } else {
4570       // We ignore free regions, we'll empty the free list afterwards.
4571       // We ignore humongous and archive regions, we're not tearing down these
4572       // sets.
4573       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4574              "it cannot be another type");
4575     }
4576     return false;
4577   }
4578 
4579   ~TearDownRegionSetsClosure() {
4580     assert(_old_set->is_empty(), "post-condition");
4581   }
4582 };
4583 
4584 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4585   assert_at_safepoint_on_vm_thread();
4586 
4587   if (!free_list_only) {
4588     TearDownRegionSetsClosure cl(&_old_set);
4589     heap_region_iterate(&cl);
4590 
4591     // Note that emptying the _young_list is postponed and instead done as
4592     // the first step when rebuilding the regions sets again. The reason for
4593     // this is that during a full GC string deduplication needs to know if
4594     // a collected region was young or old when the full GC was initiated.
4595   }
4596   _hrm->remove_all_free_regions();
4597 }
4598 
4599 void G1CollectedHeap::increase_used(size_t bytes) {
4600   _summary_bytes_used += bytes;
4601 }
4602 
4603 void G1CollectedHeap::decrease_used(size_t bytes) {
4604   assert(_summary_bytes_used >= bytes,
4605          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4606          _summary_bytes_used, bytes);
4607   _summary_bytes_used -= bytes;
4608 }
4609 
4610 void G1CollectedHeap::set_used(size_t bytes) {
4611   _summary_bytes_used = bytes;
4612 }
4613 
4614 class RebuildRegionSetsClosure : public HeapRegionClosure {
4615 private:
4616   bool _free_list_only;
4617 
4618   HeapRegionSet* _old_set;
4619   HeapRegionManager* _hrm;
4620 
4621   size_t _total_used;
4622 
4623 public:
4624   RebuildRegionSetsClosure(bool free_list_only,
4625                            HeapRegionSet* old_set,
4626                            HeapRegionManager* hrm) :
4627     _free_list_only(free_list_only),
4628     _old_set(old_set), _hrm(hrm), _total_used(0) {
4629     assert(_hrm->num_free_regions() == 0, "pre-condition");
4630     if (!free_list_only) {
4631       assert(_old_set->is_empty(), "pre-condition");
4632     }
4633   }
4634 
4635   bool do_heap_region(HeapRegion* r) {
4636     if (r->is_empty()) {
4637       assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4638       // Add free regions to the free list
4639       r->set_free();
4640       _hrm->insert_into_free_list(r);
4641     } else if (!_free_list_only) {
4642       assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4643 
4644       if (r->is_archive() || r->is_humongous()) {
4645         // We ignore archive and humongous regions. We left these sets unchanged.
4646       } else {
4647         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4648         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4649         r->move_to_old();
4650         _old_set->add(r);
4651       }
4652       _total_used += r->used();
4653     }
4654 
4655     return false;
4656   }
4657 
4658   size_t total_used() {
4659     return _total_used;
4660   }
4661 };
4662 
4663 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4664   assert_at_safepoint_on_vm_thread();
4665 
4666   if (!free_list_only) {
4667     _eden.clear();
4668     _survivor.clear();
4669   }
4670 
4671   RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4672   heap_region_iterate(&cl);
4673 
4674   if (!free_list_only) {
4675     set_used(cl.total_used());
4676     if (_archive_allocator != NULL) {
4677       _archive_allocator->clear_used();
4678     }
4679   }
4680   assert_used_and_recalculate_used_equal(this);
4681 }
4682 
4683 // Methods for the mutator alloc region
4684 
4685 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4686                                                       bool force,
4687                                                       uint node_index) {
4688   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4689   bool should_allocate = policy()->should_allocate_mutator_region();
4690   if (force || should_allocate) {
4691     HeapRegion* new_alloc_region = new_region(word_size,
4692                                               HeapRegionType::Eden,
4693                                               false /* do_expand */,
4694                                               node_index);
4695     if (new_alloc_region != NULL) {
4696       set_region_short_lived_locked(new_alloc_region);
4697       _hr_printer.alloc(new_alloc_region, !should_allocate);
4698       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4699       _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4700       return new_alloc_region;
4701     }
4702   }
4703   return NULL;
4704 }
4705 
4706 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4707                                                   size_t allocated_bytes) {
4708   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4709   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4710 
4711   collection_set()->add_eden_region(alloc_region);
4712   increase_used(allocated_bytes);
4713   _eden.add_used_bytes(allocated_bytes);
4714   _hr_printer.retire(alloc_region);
4715 
4716   // We update the eden sizes here, when the region is retired,
4717   // instead of when it's allocated, since this is the point that its
4718   // used space has been recorded in _summary_bytes_used.
4719   g1mm()->update_eden_size();
4720 }
4721 
4722 // Methods for the GC alloc regions
4723 
4724 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4725   if (dest.is_old()) {
4726     return true;
4727   } else {
4728     return survivor_regions_count() < policy()->max_survivor_regions();
4729   }
4730 }
4731 
4732 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4733   assert(FreeList_lock->owned_by_self(), "pre-condition");
4734 
4735   if (!has_more_regions(dest)) {
4736     return NULL;
4737   }
4738 
4739   HeapRegionType type;
4740   if (dest.is_young()) {
4741     type = HeapRegionType::Survivor;
4742   } else {
4743     type = HeapRegionType::Old;
4744   }
4745 
4746   HeapRegion* new_alloc_region = new_region(word_size,
4747                                             type,
4748                                             true /* do_expand */,
4749                                             node_index);
4750 
4751   if (new_alloc_region != NULL) {
4752     if (type.is_survivor()) {
4753       new_alloc_region->set_survivor();
4754       _survivor.add(new_alloc_region);
4755       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4756     } else {
4757       new_alloc_region->set_old();
4758       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4759     }
4760     _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4761     register_region_with_region_attr(new_alloc_region);
4762     _hr_printer.alloc(new_alloc_region);
4763     return new_alloc_region;
4764   }
4765   return NULL;
4766 }
4767 
4768 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4769                                              size_t allocated_bytes,
4770                                              G1HeapRegionAttr dest) {
4771   _bytes_used_during_gc += allocated_bytes;
4772   if (dest.is_old()) {
4773     old_set_add(alloc_region);
4774   } else {
4775     assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4776     _survivor.add_used_bytes(allocated_bytes);
4777   }
4778 
4779   bool const during_im = collector_state()->in_concurrent_start_gc();
4780   if (during_im && allocated_bytes > 0) {
4781     _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4782   }
4783   _hr_printer.retire(alloc_region);
4784 }
4785 
4786 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4787   bool expanded = false;
4788   uint index = _hrm->find_highest_free(&expanded);
4789 
4790   if (index != G1_NO_HRM_INDEX) {
4791     if (expanded) {
4792       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4793                                 HeapRegion::GrainWords * HeapWordSize);
4794     }
4795     return _hrm->allocate_free_regions_starting_at(index, 1);
4796   }
4797   return NULL;
4798 }
4799 
4800 // Optimized nmethod scanning
4801 
4802 class RegisterNMethodOopClosure: public OopClosure {
4803   G1CollectedHeap* _g1h;
4804   nmethod* _nm;
4805 
4806   template <class T> void do_oop_work(T* p) {
4807     T heap_oop = RawAccess<>::oop_load(p);
4808     if (!CompressedOops::is_null(heap_oop)) {
4809       oop obj = CompressedOops::decode_not_null(heap_oop);
4810       HeapRegion* hr = _g1h->heap_region_containing(obj);
4811       assert(!hr->is_continues_humongous(),
4812              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4813              " starting at " HR_FORMAT,
4814              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4815 
4816       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4817       hr->add_strong_code_root_locked(_nm);
4818     }
4819   }
4820 
4821 public:
4822   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4823     _g1h(g1h), _nm(nm) {}
4824 
4825   void do_oop(oop* p)       { do_oop_work(p); }
4826   void do_oop(narrowOop* p) { do_oop_work(p); }
4827 };
4828 
4829 class UnregisterNMethodOopClosure: public OopClosure {
4830   G1CollectedHeap* _g1h;
4831   nmethod* _nm;
4832 
4833   template <class T> void do_oop_work(T* p) {
4834     T heap_oop = RawAccess<>::oop_load(p);
4835     if (!CompressedOops::is_null(heap_oop)) {
4836       oop obj = CompressedOops::decode_not_null(heap_oop);
4837       HeapRegion* hr = _g1h->heap_region_containing(obj);
4838       assert(!hr->is_continues_humongous(),
4839              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4840              " starting at " HR_FORMAT,
4841              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4842 
4843       hr->remove_strong_code_root(_nm);
4844     }
4845   }
4846 
4847 public:
4848   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4849     _g1h(g1h), _nm(nm) {}
4850 
4851   void do_oop(oop* p)       { do_oop_work(p); }
4852   void do_oop(narrowOop* p) { do_oop_work(p); }
4853 };
4854 
4855 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4856   guarantee(nm != NULL, "sanity");
4857   RegisterNMethodOopClosure reg_cl(this, nm);
4858   nm->oops_do(&reg_cl);
4859 }
4860 
4861 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4862   guarantee(nm != NULL, "sanity");
4863   UnregisterNMethodOopClosure reg_cl(this, nm);
4864   nm->oops_do(&reg_cl, true);
4865 }
4866 
4867 void G1CollectedHeap::purge_code_root_memory() {
4868   double purge_start = os::elapsedTime();
4869   G1CodeRootSet::purge();
4870   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4871   phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4872 }
4873 
4874 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4875   G1CollectedHeap* _g1h;
4876 
4877 public:
4878   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4879     _g1h(g1h) {}
4880 
4881   void do_code_blob(CodeBlob* cb) {
4882     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4883     if (nm == NULL) {
4884       return;
4885     }
4886 
4887     _g1h->register_nmethod(nm);
4888   }
4889 };
4890 
4891 void G1CollectedHeap::rebuild_strong_code_roots() {
4892   RebuildStrongCodeRootClosure blob_cl(this);
4893   CodeCache::blobs_do(&blob_cl);
4894 }
4895 
4896 void G1CollectedHeap::initialize_serviceability() {
4897   _g1mm->initialize_serviceability();
4898 }
4899 
4900 MemoryUsage G1CollectedHeap::memory_usage() {
4901   return _g1mm->memory_usage();
4902 }
4903 
4904 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4905   return _g1mm->memory_managers();
4906 }
4907 
4908 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4909   return _g1mm->memory_pools();
4910 }
--- EOF ---