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/g1ServiceThread.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/heapInspection.hpp"
  93 #include "memory/resourceArea.hpp"
  94 #include "memory/universe.hpp"
  95 #include "oops/access.inline.hpp"
  96 #include "oops/compressedOops.inline.hpp"
  97 #include "oops/oop.inline.hpp"
  98 #include "runtime/atomic.hpp"
  99 #include "runtime/handles.inline.hpp"
 100 #include "runtime/init.hpp"
 101 #include "runtime/orderAccess.hpp"
 102 #include "runtime/threadSMR.hpp"
 103 #include "runtime/vmThread.hpp"
 104 #include "utilities/align.hpp"
 105 #include "utilities/autoRestore.hpp"
 106 #include "utilities/bitMap.inline.hpp"
 107 #include "utilities/globalDefinitions.hpp"
 108 #include "utilities/stack.inline.hpp"
 109 
 110 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
 111 
 112 // INVARIANTS/NOTES
 113 //
 114 // All allocation activity covered by the G1CollectedHeap interface is
 115 // serialized by acquiring the HeapLock.  This happens in mem_allocate
 116 // and allocate_new_tlab, which are the "entry" points to the
 117 // allocation code from the rest of the JVM.  (Note that this does not
 118 // apply to TLAB allocation, which is not part of this interface: it
 119 // is done by clients of this interface.)
 120 
 121 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
 122  private:
 123   size_t _num_dirtied;
 124   G1CollectedHeap* _g1h;
 125   G1CardTable* _g1_ct;
 126 
 127   HeapRegion* region_for_card(CardValue* card_ptr) const {
 128     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
 129   }
 130 
 131   bool will_become_free(HeapRegion* hr) const {
 132     // A region will be freed by free_collection_set if the region is in the
 133     // collection set and has not had an evacuation failure.
 134     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 135   }
 136 
 137  public:
 138   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
 139     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
 140 
 141   void do_card_ptr(CardValue* card_ptr, uint worker_id) {
 142     HeapRegion* hr = region_for_card(card_ptr);
 143 
 144     // Should only dirty cards in regions that won't be freed.
 145     if (!will_become_free(hr)) {
 146       *card_ptr = G1CardTable::dirty_card_val();
 147       _num_dirtied++;
 148     }
 149   }
 150 
 151   size_t num_dirtied()   const { return _num_dirtied; }
 152 };
 153 
 154 
 155 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 156   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 157 }
 158 
 159 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 160   // The from card cache is not the memory that is actually committed. So we cannot
 161   // take advantage of the zero_filled parameter.
 162   reset_from_card_cache(start_idx, num_regions);
 163 }
 164 
 165 Tickspan G1CollectedHeap::run_task_timed(AbstractGangTask* task) {
 166   Ticks start = Ticks::now();
 167   workers()->run_task(task);
 168   return Ticks::now() - start;
 169 }
 170 
 171 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 172                                              MemRegion mr) {
 173   return new HeapRegion(hrs_index, bot(), mr);
 174 }
 175 
 176 // Private methods.
 177 
 178 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
 179                                         HeapRegionType type,
 180                                         bool do_expand,
 181                                         uint node_index) {
 182   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 183          "the only time we use this to allocate a humongous region is "
 184          "when we are allocating a single humongous region");
 185 
 186   HeapRegion* res = _hrm->allocate_free_region(type, node_index);
 187 
 188   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 189     // Currently, only attempts to allocate GC alloc regions set
 190     // do_expand to true. So, we should only reach here during a
 191     // safepoint. If this assumption changes we might have to
 192     // reconsider the use of _expand_heap_after_alloc_failure.
 193     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 194 
 195     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 196                               word_size * HeapWordSize);
 197 
 198     assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
 199            "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
 200            word_size * HeapWordSize);
 201     if (expand_single_region(node_index)) {
 202       // Given that expand_single_region() succeeded in expanding the heap, and we
 203       // always expand the heap by an amount aligned to the heap
 204       // region size, the free list should in theory not be empty.
 205       // In either case allocate_free_region() will check for NULL.
 206       res = _hrm->allocate_free_region(type, node_index);
 207     } else {
 208       _expand_heap_after_alloc_failure = false;
 209     }
 210   }
 211   return res;
 212 }
 213 
 214 HeapWord*
 215 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
 216                                                            uint num_regions,
 217                                                            size_t word_size) {
 218   assert(first_hr != NULL, "pre-condition");
 219   assert(is_humongous(word_size), "word_size should be humongous");
 220   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 221 
 222   // Index of last region in the series.
 223   uint first = first_hr->hrm_index();
 224   uint last = first + num_regions - 1;
 225 
 226   // We need to initialize the region(s) we just discovered. This is
 227   // a bit tricky given that it can happen concurrently with
 228   // refinement threads refining cards on these regions and
 229   // potentially wanting to refine the BOT as they are scanning
 230   // those cards (this can happen shortly after a cleanup; see CR
 231   // 6991377). So we have to set up the region(s) carefully and in
 232   // a specific order.
 233 
 234   // The word size sum of all the regions we will allocate.
 235   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 236   assert(word_size <= word_size_sum, "sanity");
 237 
 238   // The passed in hr will be the "starts humongous" region. The header
 239   // of the new object will be placed at the bottom of this region.
 240   HeapWord* new_obj = first_hr->bottom();
 241   // This will be the new top of the new object.
 242   HeapWord* obj_top = new_obj + word_size;
 243 
 244   // First, we need to zero the header of the space that we will be
 245   // allocating. When we update top further down, some refinement
 246   // threads might try to scan the region. By zeroing the header we
 247   // ensure that any thread that will try to scan the region will
 248   // come across the zero klass word and bail out.
 249   //
 250   // NOTE: It would not have been correct to have used
 251   // CollectedHeap::fill_with_object() and make the space look like
 252   // an int array. The thread that is doing the allocation will
 253   // later update the object header to a potentially different array
 254   // type and, for a very short period of time, the klass and length
 255   // fields will be inconsistent. This could cause a refinement
 256   // thread to calculate the object size incorrectly.
 257   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 258 
 259   // Next, pad out the unused tail of the last region with filler
 260   // objects, for improved usage accounting.
 261   // How many words we use for filler objects.
 262   size_t word_fill_size = word_size_sum - word_size;
 263 
 264   // How many words memory we "waste" which cannot hold a filler object.
 265   size_t words_not_fillable = 0;
 266 
 267   if (word_fill_size >= min_fill_size()) {
 268     fill_with_objects(obj_top, word_fill_size);
 269   } else if (word_fill_size > 0) {
 270     // We have space to fill, but we cannot fit an object there.
 271     words_not_fillable = word_fill_size;
 272     word_fill_size = 0;
 273   }
 274 
 275   // We will set up the first region as "starts humongous". This
 276   // will also update the BOT covering all the regions to reflect
 277   // that there is a single object that starts at the bottom of the
 278   // first region.
 279   first_hr->set_starts_humongous(obj_top, word_fill_size);
 280   _policy->remset_tracker()->update_at_allocate(first_hr);
 281   // Then, if there are any, we will set up the "continues
 282   // humongous" regions.
 283   HeapRegion* hr = NULL;
 284   for (uint i = first + 1; i <= last; ++i) {
 285     hr = region_at(i);
 286     hr->set_continues_humongous(first_hr);
 287     _policy->remset_tracker()->update_at_allocate(hr);
 288   }
 289 
 290   // Up to this point no concurrent thread would have been able to
 291   // do any scanning on any region in this series. All the top
 292   // fields still point to bottom, so the intersection between
 293   // [bottom,top] and [card_start,card_end] will be empty. Before we
 294   // update the top fields, we'll do a storestore to make sure that
 295   // no thread sees the update to top before the zeroing of the
 296   // object header and the BOT initialization.
 297   OrderAccess::storestore();
 298 
 299   // Now, we will update the top fields of the "continues humongous"
 300   // regions except the last one.
 301   for (uint i = first; i < last; ++i) {
 302     hr = region_at(i);
 303     hr->set_top(hr->end());
 304   }
 305 
 306   hr = region_at(last);
 307   // If we cannot fit a filler object, we must set top to the end
 308   // of the humongous object, otherwise we cannot iterate the heap
 309   // and the BOT will not be complete.
 310   hr->set_top(hr->end() - words_not_fillable);
 311 
 312   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 313          "obj_top should be in last region");
 314 
 315   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 316 
 317   assert(words_not_fillable == 0 ||
 318          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 319          "Miscalculation in humongous allocation");
 320 
 321   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 322 
 323   for (uint i = first; i <= last; ++i) {
 324     hr = region_at(i);
 325     _humongous_set.add(hr);
 326     _hr_printer.alloc(hr);
 327   }
 328 
 329   return new_obj;
 330 }
 331 
 332 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 333   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 334   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 335 }
 336 
 337 // If could fit into free regions w/o expansion, try.
 338 // Otherwise, if can expand, do so.
 339 // Otherwise, if using ex regions might help, try with ex given back.
 340 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 341   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 342 
 343   _verifier->verify_region_sets_optional();
 344 
 345   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 346 
 347   // Policy: First try to allocate a humongous object in the free list.
 348   HeapRegion* humongous_start = _hrm->allocate_humongous(obj_regions);
 349   if (humongous_start == NULL) {
 350     // Policy: We could not find enough regions for the humongous object in the
 351     // free list. Look through the heap to find a mix of free and uncommitted regions.
 352     // If so, expand the heap and allocate the humongous object.
 353     humongous_start = _hrm->expand_and_allocate_humongous(obj_regions);
 354     if (humongous_start != NULL) {
 355       // We managed to find a region by expanding the heap.
 356       log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
 357                                 word_size * HeapWordSize);
 358       policy()->record_new_heap_size(num_regions());
 359     } else {
 360       // Policy: Potentially trigger a defragmentation GC.
 361     }
 362   }
 363 
 364   HeapWord* result = NULL;
 365   if (humongous_start != NULL) {
 366     result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
 367     assert(result != NULL, "it should always return a valid result");
 368 
 369     // A successful humongous object allocation changes the used space
 370     // information of the old generation so we need to recalculate the
 371     // sizes and update the jstat counters here.
 372     g1mm()->update_sizes();
 373   }
 374 
 375   _verifier->verify_region_sets_optional();
 376 
 377   return result;
 378 }
 379 
 380 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
 381                                              size_t requested_size,
 382                                              size_t* actual_size) {
 383   assert_heap_not_locked_and_not_at_safepoint();
 384   assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
 385 
 386   return attempt_allocation(min_size, requested_size, actual_size);
 387 }
 388 
 389 HeapWord*
 390 G1CollectedHeap::mem_allocate(size_t word_size,
 391                               bool*  gc_overhead_limit_was_exceeded) {
 392   assert_heap_not_locked_and_not_at_safepoint();
 393 
 394   if (is_humongous(word_size)) {
 395     return attempt_allocation_humongous(word_size);
 396   }
 397   size_t dummy = 0;
 398   return attempt_allocation(word_size, word_size, &dummy);
 399 }
 400 
 401 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 402   ResourceMark rm; // For retrieving the thread names in log messages.
 403 
 404   // Make sure you read the note in attempt_allocation_humongous().
 405 
 406   assert_heap_not_locked_and_not_at_safepoint();
 407   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 408          "be called for humongous allocation requests");
 409 
 410   // We should only get here after the first-level allocation attempt
 411   // (attempt_allocation()) failed to allocate.
 412 
 413   // We will loop until a) we manage to successfully perform the
 414   // allocation or b) we successfully schedule a collection which
 415   // fails to perform the allocation. b) is the only case when we'll
 416   // return NULL.
 417   HeapWord* result = NULL;
 418   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 419     bool should_try_gc;
 420     uint gc_count_before;
 421 
 422     {
 423       MutexLocker x(Heap_lock);
 424       result = _allocator->attempt_allocation_locked(word_size);
 425       if (result != NULL) {
 426         return result;
 427       }
 428 
 429       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 430       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 431       // waiting because the GCLocker is active to not wait too long.
 432       if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
 433         // No need for an ergo message here, can_expand_young_list() does this when
 434         // it returns true.
 435         result = _allocator->attempt_allocation_force(word_size);
 436         if (result != NULL) {
 437           return result;
 438         }
 439       }
 440       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 441       // the GCLocker initiated GC has been performed and then retry. This includes
 442       // the case when the GC Locker is not active but has not been performed.
 443       should_try_gc = !GCLocker::needs_gc();
 444       // Read the GC count while still holding the Heap_lock.
 445       gc_count_before = total_collections();
 446     }
 447 
 448     if (should_try_gc) {
 449       bool succeeded;
 450       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 451                                    GCCause::_g1_inc_collection_pause);
 452       if (result != NULL) {
 453         assert(succeeded, "only way to get back a non-NULL result");
 454         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 455                              Thread::current()->name(), p2i(result));
 456         return result;
 457       }
 458 
 459       if (succeeded) {
 460         // We successfully scheduled a collection which failed to allocate. No
 461         // point in trying to allocate further. We'll just return NULL.
 462         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 463                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 464         return NULL;
 465       }
 466       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 467                            Thread::current()->name(), word_size);
 468     } else {
 469       // Failed to schedule a collection.
 470       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 471         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 472                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 473         return NULL;
 474       }
 475       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 476       // The GCLocker is either active or the GCLocker initiated
 477       // GC has not yet been performed. Stall until it is and
 478       // then retry the allocation.
 479       GCLocker::stall_until_clear();
 480       gclocker_retry_count += 1;
 481     }
 482 
 483     // We can reach here if we were unsuccessful in scheduling a
 484     // collection (because another thread beat us to it) or if we were
 485     // stalled due to the GC locker. In either can we should retry the
 486     // allocation attempt in case another thread successfully
 487     // performed a collection and reclaimed enough space. We do the
 488     // first attempt (without holding the Heap_lock) here and the
 489     // follow-on attempt will be at the start of the next loop
 490     // iteration (after taking the Heap_lock).
 491     size_t dummy = 0;
 492     result = _allocator->attempt_allocation(word_size, word_size, &dummy);
 493     if (result != NULL) {
 494       return result;
 495     }
 496 
 497     // Give a warning if we seem to be looping forever.
 498     if ((QueuedAllocationWarningCount > 0) &&
 499         (try_count % QueuedAllocationWarningCount == 0)) {
 500       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 501                              Thread::current()->name(), try_count, word_size);
 502     }
 503   }
 504 
 505   ShouldNotReachHere();
 506   return NULL;
 507 }
 508 
 509 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 510   assert_at_safepoint_on_vm_thread();
 511   if (_archive_allocator == NULL) {
 512     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 513   }
 514 }
 515 
 516 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 517   // Allocations in archive regions cannot be of a size that would be considered
 518   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 519   // may be different at archive-restore time.
 520   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 521 }
 522 
 523 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 524   assert_at_safepoint_on_vm_thread();
 525   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 526   if (is_archive_alloc_too_large(word_size)) {
 527     return NULL;
 528   }
 529   return _archive_allocator->archive_mem_allocate(word_size);
 530 }
 531 
 532 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 533                                               size_t end_alignment_in_bytes) {
 534   assert_at_safepoint_on_vm_thread();
 535   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 536 
 537   // Call complete_archive to do the real work, filling in the MemRegion
 538   // array with the archive regions.
 539   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 540   delete _archive_allocator;
 541   _archive_allocator = NULL;
 542 }
 543 
 544 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 545   assert(ranges != NULL, "MemRegion array NULL");
 546   assert(count != 0, "No MemRegions provided");
 547   MemRegion reserved = _hrm->reserved();
 548   for (size_t i = 0; i < count; i++) {
 549     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 550       return false;
 551     }
 552   }
 553   return true;
 554 }
 555 
 556 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 557                                             size_t count,
 558                                             bool open) {
 559   assert(!is_init_completed(), "Expect to be called at JVM init time");
 560   assert(ranges != NULL, "MemRegion array NULL");
 561   assert(count != 0, "No MemRegions provided");
 562   MutexLocker x(Heap_lock);
 563 
 564   MemRegion reserved = _hrm->reserved();
 565   HeapWord* prev_last_addr = NULL;
 566   HeapRegion* prev_last_region = NULL;
 567 
 568   // Temporarily disable pretouching of heap pages. This interface is used
 569   // when mmap'ing archived heap data in, so pre-touching is wasted.
 570   FlagSetting fs(AlwaysPreTouch, false);
 571 
 572   // Enable archive object checking used by G1MarkSweep. We have to let it know
 573   // about each archive range, so that objects in those ranges aren't marked.
 574   G1ArchiveAllocator::enable_archive_object_check();
 575 
 576   // For each specified MemRegion range, allocate the corresponding G1
 577   // regions and mark them as archive regions. We expect the ranges
 578   // in ascending starting address order, without overlap.
 579   for (size_t i = 0; i < count; i++) {
 580     MemRegion curr_range = ranges[i];
 581     HeapWord* start_address = curr_range.start();
 582     size_t word_size = curr_range.word_size();
 583     HeapWord* last_address = curr_range.last();
 584     size_t commits = 0;
 585 
 586     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 587               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 588               p2i(start_address), p2i(last_address));
 589     guarantee(start_address > prev_last_addr,
 590               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 591               p2i(start_address), p2i(prev_last_addr));
 592     prev_last_addr = last_address;
 593 
 594     // Check for ranges that start in the same G1 region in which the previous
 595     // range ended, and adjust the start address so we don't try to allocate
 596     // the same region again. If the current range is entirely within that
 597     // region, skip it, just adjusting the recorded top.
 598     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 599     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 600       start_address = start_region->end();
 601       if (start_address > last_address) {
 602         increase_used(word_size * HeapWordSize);
 603         start_region->set_top(last_address + 1);
 604         continue;
 605       }
 606       start_region->set_top(start_address);
 607       curr_range = MemRegion(start_address, last_address + 1);
 608       start_region = _hrm->addr_to_region(start_address);
 609     }
 610 
 611     // Perform the actual region allocation, exiting if it fails.
 612     // Then note how much new space we have allocated.
 613     if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
 614       return false;
 615     }
 616     increase_used(word_size * HeapWordSize);
 617     if (commits != 0) {
 618       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 619                                 HeapRegion::GrainWords * HeapWordSize * commits);
 620 
 621     }
 622 
 623     // Mark each G1 region touched by the range as archive, add it to
 624     // the old set, and set top.
 625     HeapRegion* curr_region = _hrm->addr_to_region(start_address);
 626     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 627     prev_last_region = last_region;
 628 
 629     while (curr_region != NULL) {
 630       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 631              "Region already in use (index %u)", curr_region->hrm_index());
 632       if (open) {
 633         curr_region->set_open_archive();
 634       } else {
 635         curr_region->set_closed_archive();
 636       }
 637       _hr_printer.alloc(curr_region);
 638       _archive_set.add(curr_region);
 639       HeapWord* top;
 640       HeapRegion* next_region;
 641       if (curr_region != last_region) {
 642         top = curr_region->end();
 643         next_region = _hrm->next_region_in_heap(curr_region);
 644       } else {
 645         top = last_address + 1;
 646         next_region = NULL;
 647       }
 648       curr_region->set_top(top);
 649       curr_region = next_region;
 650     }
 651 
 652     // Notify mark-sweep of the archive
 653     G1ArchiveAllocator::set_range_archive(curr_range, open);
 654   }
 655   return true;
 656 }
 657 
 658 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 659   assert(!is_init_completed(), "Expect to be called at JVM init time");
 660   assert(ranges != NULL, "MemRegion array NULL");
 661   assert(count != 0, "No MemRegions provided");
 662   MemRegion reserved = _hrm->reserved();
 663   HeapWord *prev_last_addr = NULL;
 664   HeapRegion* prev_last_region = NULL;
 665 
 666   // For each MemRegion, create filler objects, if needed, in the G1 regions
 667   // that contain the address range. The address range actually within the
 668   // MemRegion will not be modified. That is assumed to have been initialized
 669   // elsewhere, probably via an mmap of archived heap data.
 670   MutexLocker x(Heap_lock);
 671   for (size_t i = 0; i < count; i++) {
 672     HeapWord* start_address = ranges[i].start();
 673     HeapWord* last_address = ranges[i].last();
 674 
 675     assert(reserved.contains(start_address) && reserved.contains(last_address),
 676            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 677            p2i(start_address), p2i(last_address));
 678     assert(start_address > prev_last_addr,
 679            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 680            p2i(start_address), p2i(prev_last_addr));
 681 
 682     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 683     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 684     HeapWord* bottom_address = start_region->bottom();
 685 
 686     // Check for a range beginning in the same region in which the
 687     // previous one ended.
 688     if (start_region == prev_last_region) {
 689       bottom_address = prev_last_addr + 1;
 690     }
 691 
 692     // Verify that the regions were all marked as archive regions by
 693     // alloc_archive_regions.
 694     HeapRegion* curr_region = start_region;
 695     while (curr_region != NULL) {
 696       guarantee(curr_region->is_archive(),
 697                 "Expected archive region at index %u", curr_region->hrm_index());
 698       if (curr_region != last_region) {
 699         curr_region = _hrm->next_region_in_heap(curr_region);
 700       } else {
 701         curr_region = NULL;
 702       }
 703     }
 704 
 705     prev_last_addr = last_address;
 706     prev_last_region = last_region;
 707 
 708     // Fill the memory below the allocated range with dummy object(s),
 709     // if the region bottom does not match the range start, or if the previous
 710     // range ended within the same G1 region, and there is a gap.
 711     if (start_address != bottom_address) {
 712       size_t fill_size = pointer_delta(start_address, bottom_address);
 713       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 714       increase_used(fill_size * HeapWordSize);
 715     }
 716   }
 717 }
 718 
 719 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
 720                                                      size_t desired_word_size,
 721                                                      size_t* actual_word_size) {
 722   assert_heap_not_locked_and_not_at_safepoint();
 723   assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
 724          "be called for humongous allocation requests");
 725 
 726   HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
 727 
 728   if (result == NULL) {
 729     *actual_word_size = desired_word_size;
 730     result = attempt_allocation_slow(desired_word_size);
 731   }
 732 
 733   assert_heap_not_locked();
 734   if (result != NULL) {
 735     assert(*actual_word_size != 0, "Actual size must have been set here");
 736     dirty_young_block(result, *actual_word_size);
 737   } else {
 738     *actual_word_size = 0;
 739   }
 740 
 741   return result;
 742 }
 743 
 744 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 745   assert(!is_init_completed(), "Expect to be called at JVM init time");
 746   assert(ranges != NULL, "MemRegion array NULL");
 747   assert(count != 0, "No MemRegions provided");
 748   MemRegion reserved = _hrm->reserved();
 749   HeapWord* prev_last_addr = NULL;
 750   HeapRegion* prev_last_region = NULL;
 751   size_t size_used = 0;
 752   size_t uncommitted_regions = 0;
 753 
 754   // For each Memregion, free the G1 regions that constitute it, and
 755   // notify mark-sweep that the range is no longer to be considered 'archive.'
 756   MutexLocker x(Heap_lock);
 757   for (size_t i = 0; i < count; i++) {
 758     HeapWord* start_address = ranges[i].start();
 759     HeapWord* last_address = ranges[i].last();
 760 
 761     assert(reserved.contains(start_address) && reserved.contains(last_address),
 762            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 763            p2i(start_address), p2i(last_address));
 764     assert(start_address > prev_last_addr,
 765            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 766            p2i(start_address), p2i(prev_last_addr));
 767     size_used += ranges[i].byte_size();
 768     prev_last_addr = last_address;
 769 
 770     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 771     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 772 
 773     // Check for ranges that start in the same G1 region in which the previous
 774     // range ended, and adjust the start address so we don't try to free
 775     // the same region again. If the current range is entirely within that
 776     // region, skip it.
 777     if (start_region == prev_last_region) {
 778       start_address = start_region->end();
 779       if (start_address > last_address) {
 780         continue;
 781       }
 782       start_region = _hrm->addr_to_region(start_address);
 783     }
 784     prev_last_region = last_region;
 785 
 786     // After verifying that each region was marked as an archive region by
 787     // alloc_archive_regions, set it free and empty and uncommit it.
 788     HeapRegion* curr_region = start_region;
 789     while (curr_region != NULL) {
 790       guarantee(curr_region->is_archive(),
 791                 "Expected archive region at index %u", curr_region->hrm_index());
 792       uint curr_index = curr_region->hrm_index();
 793       _archive_set.remove(curr_region);
 794       curr_region->set_free();
 795       curr_region->set_top(curr_region->bottom());
 796       if (curr_region != last_region) {
 797         curr_region = _hrm->next_region_in_heap(curr_region);
 798       } else {
 799         curr_region = NULL;
 800       }
 801       _hrm->shrink_at(curr_index, 1);
 802       uncommitted_regions++;
 803     }
 804 
 805     // Notify mark-sweep that this is no longer an archive range.
 806     G1ArchiveAllocator::clear_range_archive(ranges[i]);
 807   }
 808 
 809   if (uncommitted_regions != 0) {
 810     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 811                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 812   }
 813   decrease_used(size_used);
 814 }
 815 
 816 oop G1CollectedHeap::materialize_archived_object(oop obj) {
 817   assert(obj != NULL, "archived obj is NULL");
 818   assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
 819 
 820   // Loading an archived object makes it strongly reachable. If it is
 821   // loaded during concurrent marking, it must be enqueued to the SATB
 822   // queue, shading the previously white object gray.
 823   G1BarrierSet::enqueue(obj);
 824 
 825   return obj;
 826 }
 827 
 828 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 829   ResourceMark rm; // For retrieving the thread names in log messages.
 830 
 831   // The structure of this method has a lot of similarities to
 832   // attempt_allocation_slow(). The reason these two were not merged
 833   // into a single one is that such a method would require several "if
 834   // allocation is not humongous do this, otherwise do that"
 835   // conditional paths which would obscure its flow. In fact, an early
 836   // version of this code did use a unified method which was harder to
 837   // follow and, as a result, it had subtle bugs that were hard to
 838   // track down. So keeping these two methods separate allows each to
 839   // be more readable. It will be good to keep these two in sync as
 840   // much as possible.
 841 
 842   assert_heap_not_locked_and_not_at_safepoint();
 843   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 844          "should only be called for humongous allocations");
 845 
 846   // Humongous objects can exhaust the heap quickly, so we should check if we
 847   // need to start a marking cycle at each humongous object allocation. We do
 848   // the check before we do the actual allocation. The reason for doing it
 849   // before the allocation is that we avoid having to keep track of the newly
 850   // allocated memory while we do a GC.
 851   if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
 852                                            word_size)) {
 853     collect(GCCause::_g1_humongous_allocation);
 854   }
 855 
 856   // We will loop until a) we manage to successfully perform the
 857   // allocation or b) we successfully schedule a collection which
 858   // fails to perform the allocation. b) is the only case when we'll
 859   // return NULL.
 860   HeapWord* result = NULL;
 861   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 862     bool should_try_gc;
 863     uint gc_count_before;
 864 
 865 
 866     {
 867       MutexLocker x(Heap_lock);
 868 
 869       // Given that humongous objects are not allocated in young
 870       // regions, we'll first try to do the allocation without doing a
 871       // collection hoping that there's enough space in the heap.
 872       result = humongous_obj_allocate(word_size);
 873       if (result != NULL) {
 874         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 875         policy()->old_gen_alloc_tracker()->
 876           add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 877         return result;
 878       }
 879 
 880       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 881       // the GCLocker initiated GC has been performed and then retry. This includes
 882       // the case when the GC Locker is not active but has not been performed.
 883       should_try_gc = !GCLocker::needs_gc();
 884       // Read the GC count while still holding the Heap_lock.
 885       gc_count_before = total_collections();
 886     }
 887 
 888     if (should_try_gc) {
 889       bool succeeded;
 890       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 891                                    GCCause::_g1_humongous_allocation);
 892       if (result != NULL) {
 893         assert(succeeded, "only way to get back a non-NULL result");
 894         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 895                              Thread::current()->name(), p2i(result));
 896         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 897         policy()->old_gen_alloc_tracker()->
 898           record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
 899         return result;
 900       }
 901 
 902       if (succeeded) {
 903         // We successfully scheduled a collection which failed to allocate. No
 904         // point in trying to allocate further. We'll just return NULL.
 905         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 906                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 907         return NULL;
 908       }
 909       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 910                            Thread::current()->name(), word_size);
 911     } else {
 912       // Failed to schedule a collection.
 913       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 914         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 915                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 916         return NULL;
 917       }
 918       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 919       // The GCLocker is either active or the GCLocker initiated
 920       // GC has not yet been performed. Stall until it is and
 921       // then retry the allocation.
 922       GCLocker::stall_until_clear();
 923       gclocker_retry_count += 1;
 924     }
 925 
 926 
 927     // We can reach here if we were unsuccessful in scheduling a
 928     // collection (because another thread beat us to it) or if we were
 929     // stalled due to the GC locker. In either can we should retry the
 930     // allocation attempt in case another thread successfully
 931     // performed a collection and reclaimed enough space.
 932     // Humongous object allocation always needs a lock, so we wait for the retry
 933     // in the next iteration of the loop, unlike for the regular iteration case.
 934     // Give a warning if we seem to be looping forever.
 935 
 936     if ((QueuedAllocationWarningCount > 0) &&
 937         (try_count % QueuedAllocationWarningCount == 0)) {
 938       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 939                              Thread::current()->name(), try_count, word_size);
 940     }
 941   }
 942 
 943   ShouldNotReachHere();
 944   return NULL;
 945 }
 946 
 947 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 948                                                            bool expect_null_mutator_alloc_region) {
 949   assert_at_safepoint_on_vm_thread();
 950   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 951          "the current alloc region was unexpectedly found to be non-NULL");
 952 
 953   if (!is_humongous(word_size)) {
 954     return _allocator->attempt_allocation_locked(word_size);
 955   } else {
 956     HeapWord* result = humongous_obj_allocate(word_size);
 957     if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
 958       collector_state()->set_initiate_conc_mark_if_possible(true);
 959     }
 960     return result;
 961   }
 962 
 963   ShouldNotReachHere();
 964 }
 965 
 966 class PostCompactionPrinterClosure: public HeapRegionClosure {
 967 private:
 968   G1HRPrinter* _hr_printer;
 969 public:
 970   bool do_heap_region(HeapRegion* hr) {
 971     assert(!hr->is_young(), "not expecting to find young regions");
 972     _hr_printer->post_compaction(hr);
 973     return false;
 974   }
 975 
 976   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 977     : _hr_printer(hr_printer) { }
 978 };
 979 
 980 void G1CollectedHeap::print_hrm_post_compaction() {
 981   if (_hr_printer.is_active()) {
 982     PostCompactionPrinterClosure cl(hr_printer());
 983     heap_region_iterate(&cl);
 984   }
 985 }
 986 
 987 void G1CollectedHeap::abort_concurrent_cycle() {
 988   // If we start the compaction before the CM threads finish
 989   // scanning the root regions we might trip them over as we'll
 990   // be moving objects / updating references. So let's wait until
 991   // they are done. By telling them to abort, they should complete
 992   // early.
 993   _cm->root_regions()->abort();
 994   _cm->root_regions()->wait_until_scan_finished();
 995 
 996   // Disable discovery and empty the discovered lists
 997   // for the CM ref processor.
 998   _ref_processor_cm->disable_discovery();
 999   _ref_processor_cm->abandon_partial_discovery();
1000   _ref_processor_cm->verify_no_references_recorded();
1001 
1002   // Abandon current iterations of concurrent marking and concurrent
1003   // refinement, if any are in progress.
1004   concurrent_mark()->concurrent_cycle_abort();
1005 }
1006 
1007 void G1CollectedHeap::prepare_heap_for_full_collection() {
1008   // Make sure we'll choose a new allocation region afterwards.
1009   _allocator->release_mutator_alloc_regions();
1010   _allocator->abandon_gc_alloc_regions();
1011 
1012   // We may have added regions to the current incremental collection
1013   // set between the last GC or pause and now. We need to clear the
1014   // incremental collection set and then start rebuilding it afresh
1015   // after this full GC.
1016   abandon_collection_set(collection_set());
1017 
1018   tear_down_region_sets(false /* free_list_only */);
1019 
1020   hrm()->prepare_for_full_collection_start();
1021 }
1022 
1023 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1024   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1025   assert_used_and_recalculate_used_equal(this);
1026   _verifier->verify_region_sets_optional();
1027   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1028   _verifier->check_bitmaps("Full GC Start");
1029 }
1030 
1031 void G1CollectedHeap::prepare_heap_for_mutators() {
1032   hrm()->prepare_for_full_collection_end();
1033 
1034   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1035   ClassLoaderDataGraph::purge();
1036   MetaspaceUtils::verify_metrics();
1037 
1038   // Prepare heap for normal collections.
1039   assert(num_free_regions() == 0, "we should not have added any free regions");
1040   rebuild_region_sets(false /* free_list_only */);
1041   abort_refinement();
1042   resize_heap_if_necessary();
1043 
1044   // Rebuild the strong code root lists for each region
1045   rebuild_strong_code_roots();
1046 
1047   // Purge code root memory
1048   purge_code_root_memory();
1049 
1050   // Start a new incremental collection set for the next pause
1051   start_new_collection_set();
1052 
1053   _allocator->init_mutator_alloc_regions();
1054 
1055   // Post collection state updates.
1056   MetaspaceGC::compute_new_size();
1057 }
1058 
1059 void G1CollectedHeap::abort_refinement() {
1060   if (_hot_card_cache->use_cache()) {
1061     _hot_card_cache->reset_hot_cache();
1062   }
1063 
1064   // Discard all remembered set updates and reset refinement statistics.
1065   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1066   assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1067          "DCQS should be empty");
1068   concurrent_refine()->get_and_reset_refinement_stats();
1069 }
1070 
1071 void G1CollectedHeap::verify_after_full_collection() {
1072   _hrm->verify_optional();
1073   _verifier->verify_region_sets_optional();
1074   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1075   // Clear the previous marking bitmap, if needed for bitmap verification.
1076   // Note we cannot do this when we clear the next marking bitmap in
1077   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1078   // objects marked during a full GC against the previous bitmap.
1079   // But we need to clear it before calling check_bitmaps below since
1080   // the full GC has compacted objects and updated TAMS but not updated
1081   // the prev bitmap.
1082   if (G1VerifyBitmaps) {
1083     GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1084     _cm->clear_prev_bitmap(workers());
1085   }
1086   // This call implicitly verifies that the next bitmap is clear after Full GC.
1087   _verifier->check_bitmaps("Full GC End");
1088 
1089   // At this point there should be no regions in the
1090   // entire heap tagged as young.
1091   assert(check_young_list_empty(), "young list should be empty at this point");
1092 
1093   // Note: since we've just done a full GC, concurrent
1094   // marking is no longer active. Therefore we need not
1095   // re-enable reference discovery for the CM ref processor.
1096   // That will be done at the start of the next marking cycle.
1097   // We also know that the STW processor should no longer
1098   // discover any new references.
1099   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1100   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1101   _ref_processor_stw->verify_no_references_recorded();
1102   _ref_processor_cm->verify_no_references_recorded();
1103 }
1104 
1105 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1106   // Post collection logging.
1107   // We should do this after we potentially resize the heap so
1108   // that all the COMMIT / UNCOMMIT events are generated before
1109   // the compaction events.
1110   print_hrm_post_compaction();
1111   heap_transition->print();
1112   print_heap_after_gc();
1113   print_heap_regions();
1114 }
1115 
1116 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1117                                          bool clear_all_soft_refs) {
1118   assert_at_safepoint_on_vm_thread();
1119 
1120   if (GCLocker::check_active_before_gc()) {
1121     // Full GC was not completed.
1122     return false;
1123   }
1124 
1125   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1126       soft_ref_policy()->should_clear_all_soft_refs();
1127 
1128   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1129   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1130 
1131   collector.prepare_collection();
1132   collector.collect();
1133   collector.complete_collection();
1134 
1135   // Full collection was successfully completed.
1136   return true;
1137 }
1138 
1139 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1140   // Currently, there is no facility in the do_full_collection(bool) API to notify
1141   // the caller that the collection did not succeed (e.g., because it was locked
1142   // out by the GC locker). So, right now, we'll ignore the return value.
1143   bool dummy = do_full_collection(true,                /* explicit_gc */
1144                                   clear_all_soft_refs);
1145 }
1146 
1147 void G1CollectedHeap::resize_heap_if_necessary() {
1148   assert_at_safepoint_on_vm_thread();
1149 
1150   bool should_expand;
1151   size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
1152 
1153   if (resize_amount == 0) {
1154     return;
1155   } else if (should_expand) {
1156     expand(resize_amount, _workers);
1157   } else {
1158     shrink(resize_amount);
1159   }
1160 }
1161 
1162 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1163                                                             bool do_gc,
1164                                                             bool clear_all_soft_refs,
1165                                                             bool expect_null_mutator_alloc_region,
1166                                                             bool* gc_succeeded) {
1167   *gc_succeeded = true;
1168   // Let's attempt the allocation first.
1169   HeapWord* result =
1170     attempt_allocation_at_safepoint(word_size,
1171                                     expect_null_mutator_alloc_region);
1172   if (result != NULL) {
1173     return result;
1174   }
1175 
1176   // In a G1 heap, we're supposed to keep allocation from failing by
1177   // incremental pauses.  Therefore, at least for now, we'll favor
1178   // expansion over collection.  (This might change in the future if we can
1179   // do something smarter than full collection to satisfy a failed alloc.)
1180   result = expand_and_allocate(word_size);
1181   if (result != NULL) {
1182     return result;
1183   }
1184 
1185   if (do_gc) {
1186     // Expansion didn't work, we'll try to do a Full GC.
1187     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1188                                        clear_all_soft_refs);
1189   }
1190 
1191   return NULL;
1192 }
1193 
1194 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1195                                                      bool* succeeded) {
1196   assert_at_safepoint_on_vm_thread();
1197 
1198   // Attempts to allocate followed by Full GC.
1199   HeapWord* result =
1200     satisfy_failed_allocation_helper(word_size,
1201                                      true,  /* do_gc */
1202                                      false, /* clear_all_soft_refs */
1203                                      false, /* expect_null_mutator_alloc_region */
1204                                      succeeded);
1205 
1206   if (result != NULL || !*succeeded) {
1207     return result;
1208   }
1209 
1210   // Attempts to allocate followed by Full GC that will collect all soft references.
1211   result = satisfy_failed_allocation_helper(word_size,
1212                                             true, /* do_gc */
1213                                             true, /* clear_all_soft_refs */
1214                                             true, /* expect_null_mutator_alloc_region */
1215                                             succeeded);
1216 
1217   if (result != NULL || !*succeeded) {
1218     return result;
1219   }
1220 
1221   // Attempts to allocate, no GC
1222   result = satisfy_failed_allocation_helper(word_size,
1223                                             false, /* do_gc */
1224                                             false, /* clear_all_soft_refs */
1225                                             true,  /* expect_null_mutator_alloc_region */
1226                                             succeeded);
1227 
1228   if (result != NULL) {
1229     return result;
1230   }
1231 
1232   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1233          "Flag should have been handled and cleared prior to this point");
1234 
1235   // What else?  We might try synchronous finalization later.  If the total
1236   // space available is large enough for the allocation, then a more
1237   // complete compaction phase than we've tried so far might be
1238   // appropriate.
1239   return NULL;
1240 }
1241 
1242 // Attempting to expand the heap sufficiently
1243 // to support an allocation of the given "word_size".  If
1244 // successful, perform the allocation and return the address of the
1245 // allocated block, or else "NULL".
1246 
1247 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1248   assert_at_safepoint_on_vm_thread();
1249 
1250   _verifier->verify_region_sets_optional();
1251 
1252   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1253   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1254                             word_size * HeapWordSize);
1255 
1256 
1257   if (expand(expand_bytes, _workers)) {
1258     _hrm->verify_optional();
1259     _verifier->verify_region_sets_optional();
1260     return attempt_allocation_at_safepoint(word_size,
1261                                            false /* expect_null_mutator_alloc_region */);
1262   }
1263   return NULL;
1264 }
1265 
1266 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1267   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1268   aligned_expand_bytes = align_up(aligned_expand_bytes,
1269                                        HeapRegion::GrainBytes);
1270 
1271   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1272                             expand_bytes, aligned_expand_bytes);
1273 
1274   if (is_maximal_no_gc()) {
1275     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1276     return false;
1277   }
1278 
1279   double expand_heap_start_time_sec = os::elapsedTime();
1280   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1281   assert(regions_to_expand > 0, "Must expand by at least one region");
1282 
1283   uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1284   if (expand_time_ms != NULL) {
1285     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1286   }
1287 
1288   if (expanded_by > 0) {
1289     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1290     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1291     policy()->record_new_heap_size(num_regions());
1292   } else {
1293     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1294 
1295     // The expansion of the virtual storage space was unsuccessful.
1296     // Let's see if it was because we ran out of swap.
1297     if (G1ExitOnExpansionFailure &&
1298         _hrm->available() >= regions_to_expand) {
1299       // We had head room...
1300       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1301     }
1302   }
1303   return regions_to_expand > 0;
1304 }
1305 
1306 bool G1CollectedHeap::expand_single_region(uint node_index) {
1307   uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1308 
1309   if (expanded_by == 0) {
1310     assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1311     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1312     return false;
1313   }
1314 
1315   policy()->record_new_heap_size(num_regions());
1316   return true;
1317 }
1318 
1319 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1320   size_t aligned_shrink_bytes =
1321     ReservedSpace::page_align_size_down(shrink_bytes);
1322   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1323                                          HeapRegion::GrainBytes);
1324   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1325 
1326   uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1327   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1328 
1329   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",
1330                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1331   if (num_regions_removed > 0) {
1332     policy()->record_new_heap_size(num_regions());
1333   } else {
1334     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1335   }
1336 }
1337 
1338 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1339   _verifier->verify_region_sets_optional();
1340 
1341   // We should only reach here at the end of a Full GC or during Remark which
1342   // means we should not not be holding to any GC alloc regions. The method
1343   // below will make sure of that and do any remaining clean up.
1344   _allocator->abandon_gc_alloc_regions();
1345 
1346   // Instead of tearing down / rebuilding the free lists here, we
1347   // could instead use the remove_all_pending() method on free_list to
1348   // remove only the ones that we need to remove.
1349   tear_down_region_sets(true /* free_list_only */);
1350   shrink_helper(shrink_bytes);
1351   rebuild_region_sets(true /* free_list_only */);
1352 
1353   _hrm->verify_optional();
1354   _verifier->verify_region_sets_optional();
1355 }
1356 
1357 class OldRegionSetChecker : public HeapRegionSetChecker {
1358 public:
1359   void check_mt_safety() {
1360     // Master Old Set MT safety protocol:
1361     // (a) If we're at a safepoint, operations on the master old set
1362     // should be invoked:
1363     // - by the VM thread (which will serialize them), or
1364     // - by the GC workers while holding the FreeList_lock, if we're
1365     //   at a safepoint for an evacuation pause (this lock is taken
1366     //   anyway when an GC alloc region is retired so that a new one
1367     //   is allocated from the free list), or
1368     // - by the GC workers while holding the OldSets_lock, if we're at a
1369     //   safepoint for a cleanup pause.
1370     // (b) If we're not at a safepoint, operations on the master old set
1371     // should be invoked while holding the Heap_lock.
1372 
1373     if (SafepointSynchronize::is_at_safepoint()) {
1374       guarantee(Thread::current()->is_VM_thread() ||
1375                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1376                 "master old set MT safety protocol at a safepoint");
1377     } else {
1378       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1379     }
1380   }
1381   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1382   const char* get_description() { return "Old Regions"; }
1383 };
1384 
1385 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1386 public:
1387   void check_mt_safety() {
1388     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1389               "May only change archive regions during initialization or safepoint.");
1390   }
1391   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1392   const char* get_description() { return "Archive Regions"; }
1393 };
1394 
1395 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1396 public:
1397   void check_mt_safety() {
1398     // Humongous Set MT safety protocol:
1399     // (a) If we're at a safepoint, operations on the master humongous
1400     // set should be invoked by either the VM thread (which will
1401     // serialize them) or by the GC workers while holding the
1402     // OldSets_lock.
1403     // (b) If we're not at a safepoint, operations on the master
1404     // humongous set should be invoked while holding the Heap_lock.
1405 
1406     if (SafepointSynchronize::is_at_safepoint()) {
1407       guarantee(Thread::current()->is_VM_thread() ||
1408                 OldSets_lock->owned_by_self(),
1409                 "master humongous set MT safety protocol at a safepoint");
1410     } else {
1411       guarantee(Heap_lock->owned_by_self(),
1412                 "master humongous set MT safety protocol outside a safepoint");
1413     }
1414   }
1415   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1416   const char* get_description() { return "Humongous Regions"; }
1417 };
1418 
1419 G1CollectedHeap::G1CollectedHeap() :
1420   CollectedHeap(),
1421   _service_thread(NULL),
1422   _workers(NULL),
1423   _card_table(NULL),
1424   _collection_pause_end(Ticks::now()),
1425   _soft_ref_policy(),
1426   _old_set("Old Region Set", new OldRegionSetChecker()),
1427   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1428   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1429   _bot(NULL),
1430   _listener(),
1431   _numa(G1NUMA::create()),
1432   _hrm(NULL),
1433   _allocator(NULL),
1434   _verifier(NULL),
1435   _summary_bytes_used(0),
1436   _bytes_used_during_gc(0),
1437   _archive_allocator(NULL),
1438   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1439   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1440   _expand_heap_after_alloc_failure(true),
1441   _g1mm(NULL),
1442   _humongous_reclaim_candidates(),
1443   _has_humongous_reclaim_candidates(false),
1444   _hr_printer(),
1445   _collector_state(),
1446   _old_marking_cycles_started(0),
1447   _old_marking_cycles_completed(0),
1448   _eden(),
1449   _survivor(),
1450   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1451   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1452   _policy(G1Policy::create_policy(_gc_timer_stw)),
1453   _heap_sizing_policy(NULL),
1454   _collection_set(this, _policy),
1455   _hot_card_cache(NULL),
1456   _rem_set(NULL),
1457   _cm(NULL),
1458   _cm_thread(NULL),
1459   _cr(NULL),
1460   _task_queues(NULL),
1461   _evacuation_failed(false),
1462   _evacuation_failed_info_array(NULL),
1463   _preserved_marks_set(true /* in_c_heap */),
1464 #ifndef PRODUCT
1465   _evacuation_failure_alot_for_current_gc(false),
1466   _evacuation_failure_alot_gc_number(0),
1467   _evacuation_failure_alot_count(0),
1468 #endif
1469   _ref_processor_stw(NULL),
1470   _is_alive_closure_stw(this),
1471   _is_subject_to_discovery_stw(this),
1472   _ref_processor_cm(NULL),
1473   _is_alive_closure_cm(this),
1474   _is_subject_to_discovery_cm(this),
1475   _region_attr() {
1476 
1477   _verifier = new G1HeapVerifier(this);
1478 
1479   _allocator = new G1Allocator(this);
1480 
1481   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1482 
1483   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1484 
1485   // Override the default _filler_array_max_size so that no humongous filler
1486   // objects are created.
1487   _filler_array_max_size = _humongous_object_threshold_in_words;
1488 
1489   uint n_queues = ParallelGCThreads;
1490   _task_queues = new G1ScannerTasksQueueSet(n_queues);
1491 
1492   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1493 
1494   for (uint i = 0; i < n_queues; i++) {
1495     G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1496     q->initialize();
1497     _task_queues->register_queue(i, q);
1498     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1499   }
1500 
1501   // Initialize the G1EvacuationFailureALot counters and flags.
1502   NOT_PRODUCT(reset_evacuation_should_fail();)
1503   _gc_tracer_stw->initialize();
1504 
1505   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1506 }
1507 
1508 static size_t actual_reserved_page_size(ReservedSpace rs) {
1509   size_t page_size = os::vm_page_size();
1510   if (UseLargePages) {
1511     // There are two ways to manage large page memory.
1512     // 1. OS supports committing large page memory.
1513     // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1514     //    And ReservedSpace calls it 'special'. If we failed to set 'special',
1515     //    we reserved memory without large page.
1516     if (os::can_commit_large_page_memory() || rs.special()) {
1517       // An alignment at ReservedSpace comes from preferred page size or
1518       // heap alignment, and if the alignment came from heap alignment, it could be
1519       // larger than large pages size. So need to cap with the large page size.
1520       page_size = MIN2(rs.alignment(), os::large_page_size());
1521     }
1522   }
1523 
1524   return page_size;
1525 }
1526 
1527 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1528                                                                  size_t size,
1529                                                                  size_t translation_factor) {
1530   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1531   // Allocate a new reserved space, preferring to use large pages.
1532   ReservedSpace rs(size, preferred_page_size);
1533   size_t page_size = actual_reserved_page_size(rs);
1534   G1RegionToSpaceMapper* result  =
1535     G1RegionToSpaceMapper::create_mapper(rs,
1536                                          size,
1537                                          page_size,
1538                                          HeapRegion::GrainBytes,
1539                                          translation_factor,
1540                                          mtGC);
1541 
1542   os::trace_page_sizes_for_requested_size(description,
1543                                           size,
1544                                           preferred_page_size,
1545                                           page_size,
1546                                           rs.base(),
1547                                           rs.size());
1548 
1549   return result;
1550 }
1551 
1552 jint G1CollectedHeap::initialize_concurrent_refinement() {
1553   jint ecode = JNI_OK;
1554   _cr = G1ConcurrentRefine::create(&ecode);
1555   return ecode;
1556 }
1557 
1558 jint G1CollectedHeap::initialize_service_thread() {
1559   _service_thread = new G1ServiceThread();
1560   if (_service_thread->osthread() == NULL) {
1561     vm_shutdown_during_initialization("Could not create G1ServiceThread");
1562     return JNI_ENOMEM;
1563   }
1564   return JNI_OK;
1565 }
1566 
1567 jint G1CollectedHeap::initialize() {
1568 
1569   // Necessary to satisfy locking discipline assertions.
1570 
1571   MutexLocker x(Heap_lock);
1572 
1573   // While there are no constraints in the GC code that HeapWordSize
1574   // be any particular value, there are multiple other areas in the
1575   // system which believe this to be true (e.g. oop->object_size in some
1576   // cases incorrectly returns the size in wordSize units rather than
1577   // HeapWordSize).
1578   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1579 
1580   size_t init_byte_size = InitialHeapSize;
1581   size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1582 
1583   // Ensure that the sizes are properly aligned.
1584   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1585   Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1586   Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1587 
1588   // Reserve the maximum.
1589 
1590   // When compressed oops are enabled, the preferred heap base
1591   // is calculated by subtracting the requested size from the
1592   // 32Gb boundary and using the result as the base address for
1593   // heap reservation. If the requested size is not aligned to
1594   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1595   // into the ReservedHeapSpace constructor) then the actual
1596   // base of the reserved heap may end up differing from the
1597   // address that was requested (i.e. the preferred heap base).
1598   // If this happens then we could end up using a non-optimal
1599   // compressed oops mode.
1600 
1601   ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1602                                                      HeapAlignment);
1603 
1604   initialize_reserved_region(heap_rs);
1605 
1606   // Create the barrier set for the entire reserved region.
1607   G1CardTable* ct = new G1CardTable(heap_rs.region());
1608   ct->initialize();
1609   G1BarrierSet* bs = new G1BarrierSet(ct);
1610   bs->initialize();
1611   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1612   BarrierSet::set_barrier_set(bs);
1613   _card_table = ct;
1614 
1615   {
1616     G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1617     satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1618     satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1619   }
1620 
1621   // Create the hot card cache.
1622   _hot_card_cache = new G1HotCardCache(this);
1623 
1624   // Create space mappers.
1625   size_t page_size = actual_reserved_page_size(heap_rs);
1626   G1RegionToSpaceMapper* heap_storage =
1627     G1RegionToSpaceMapper::create_heap_mapper(heap_rs,
1628                                               heap_rs.size(),
1629                                               page_size,
1630                                               HeapRegion::GrainBytes,
1631                                               1,
1632                                               mtJavaHeap);
1633   if(heap_storage == NULL) {
1634     vm_shutdown_during_initialization("Could not initialize G1 heap");
1635     return JNI_ERR;
1636   }
1637 
1638   os::trace_page_sizes("Heap",
1639                        MinHeapSize,
1640                        reserved_byte_size,
1641                        page_size,
1642                        heap_rs.base(),
1643                        heap_rs.size());
1644   heap_storage->set_mapping_changed_listener(&_listener);
1645 
1646   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1647   G1RegionToSpaceMapper* bot_storage =
1648     create_aux_memory_mapper("Block Offset Table",
1649                              G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1650                              G1BlockOffsetTable::heap_map_factor());
1651 
1652   G1RegionToSpaceMapper* cardtable_storage =
1653     create_aux_memory_mapper("Card Table",
1654                              G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1655                              G1CardTable::heap_map_factor());
1656 
1657   G1RegionToSpaceMapper* card_counts_storage =
1658     create_aux_memory_mapper("Card Counts Table",
1659                              G1CardCounts::compute_size(heap_rs.size() / HeapWordSize),
1660                              G1CardCounts::heap_map_factor());
1661 
1662   size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1663   G1RegionToSpaceMapper* prev_bitmap_storage =
1664     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1665   G1RegionToSpaceMapper* next_bitmap_storage =
1666     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1667 
1668   _hrm = HeapRegionManager::create_manager(this);
1669 
1670   _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1671   _card_table->initialize(cardtable_storage);
1672 
1673   // Do later initialization work for concurrent refinement.
1674   _hot_card_cache->initialize(card_counts_storage);
1675 
1676   // 6843694 - ensure that the maximum region index can fit
1677   // in the remembered set structures.
1678   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1679   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1680 
1681   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1682   // start within the first card.
1683   guarantee(heap_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1684   // Also create a G1 rem set.
1685   _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1686   _rem_set->initialize(max_reserved_capacity(), max_regions());
1687 
1688   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1689   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1690   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1691             "too many cards per region");
1692 
1693   FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1694 
1695   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1696 
1697   {
1698     HeapWord* start = _hrm->reserved().start();
1699     HeapWord* end = _hrm->reserved().end();
1700     size_t granularity = HeapRegion::GrainBytes;
1701 
1702     _region_attr.initialize(start, end, granularity);
1703     _humongous_reclaim_candidates.initialize(start, end, granularity);
1704   }
1705 
1706   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1707                           true /* are_GC_task_threads */,
1708                           false /* are_ConcurrentGC_threads */);
1709   if (_workers == NULL) {
1710     return JNI_ENOMEM;
1711   }
1712   _workers->initialize_workers();
1713 
1714   _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1715 
1716   // Create the G1ConcurrentMark data structure and thread.
1717   // (Must do this late, so that "max_regions" is defined.)
1718   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1719   _cm_thread = _cm->cm_thread();
1720 
1721   // Now expand into the initial heap size.
1722   if (!expand(init_byte_size, _workers)) {
1723     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1724     return JNI_ENOMEM;
1725   }
1726 
1727   // Perform any initialization actions delegated to the policy.
1728   policy()->init(this, &_collection_set);
1729 
1730   jint ecode = initialize_concurrent_refinement();
1731   if (ecode != JNI_OK) {
1732     return ecode;
1733   }
1734 
1735   ecode = initialize_service_thread();
1736   if (ecode != JNI_OK) {
1737     return ecode;
1738   }
1739 
1740   {
1741     G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1742     dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1743     dcqs.set_max_cards(concurrent_refine()->red_zone());
1744   }
1745 
1746   // Here we allocate the dummy HeapRegion that is required by the
1747   // G1AllocRegion class.
1748   HeapRegion* dummy_region = _hrm->get_dummy_region();
1749 
1750   // We'll re-use the same region whether the alloc region will
1751   // require BOT updates or not and, if it doesn't, then a non-young
1752   // region will complain that it cannot support allocations without
1753   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1754   dummy_region->set_eden();
1755   // Make sure it's full.
1756   dummy_region->set_top(dummy_region->end());
1757   G1AllocRegion::setup(this, dummy_region);
1758 
1759   _allocator->init_mutator_alloc_regions();
1760 
1761   // Do create of the monitoring and management support so that
1762   // values in the heap have been properly initialized.
1763   _g1mm = new G1MonitoringSupport(this);
1764 
1765   G1StringDedup::initialize();
1766 
1767   _preserved_marks_set.init(ParallelGCThreads);
1768 
1769   _collection_set.initialize(max_regions());
1770 
1771   G1InitLogger::print();
1772 
1773   return JNI_OK;
1774 }
1775 
1776 void G1CollectedHeap::stop() {
1777   // Stop all concurrent threads. We do this to make sure these threads
1778   // do not continue to execute and access resources (e.g. logging)
1779   // that are destroyed during shutdown.
1780   _cr->stop();
1781   _service_thread->stop();
1782   _cm_thread->stop();
1783   if (G1StringDedup::is_enabled()) {
1784     G1StringDedup::stop();
1785   }
1786 }
1787 
1788 void G1CollectedHeap::safepoint_synchronize_begin() {
1789   SuspendibleThreadSet::synchronize();
1790 }
1791 
1792 void G1CollectedHeap::safepoint_synchronize_end() {
1793   SuspendibleThreadSet::desynchronize();
1794 }
1795 
1796 void G1CollectedHeap::post_initialize() {
1797   CollectedHeap::post_initialize();
1798   ref_processing_init();
1799 }
1800 
1801 void G1CollectedHeap::ref_processing_init() {
1802   // Reference processing in G1 currently works as follows:
1803   //
1804   // * There are two reference processor instances. One is
1805   //   used to record and process discovered references
1806   //   during concurrent marking; the other is used to
1807   //   record and process references during STW pauses
1808   //   (both full and incremental).
1809   // * Both ref processors need to 'span' the entire heap as
1810   //   the regions in the collection set may be dotted around.
1811   //
1812   // * For the concurrent marking ref processor:
1813   //   * Reference discovery is enabled at concurrent start.
1814   //   * Reference discovery is disabled and the discovered
1815   //     references processed etc during remarking.
1816   //   * Reference discovery is MT (see below).
1817   //   * Reference discovery requires a barrier (see below).
1818   //   * Reference processing may or may not be MT
1819   //     (depending on the value of ParallelRefProcEnabled
1820   //     and ParallelGCThreads).
1821   //   * A full GC disables reference discovery by the CM
1822   //     ref processor and abandons any entries on it's
1823   //     discovered lists.
1824   //
1825   // * For the STW processor:
1826   //   * Non MT discovery is enabled at the start of a full GC.
1827   //   * Processing and enqueueing during a full GC is non-MT.
1828   //   * During a full GC, references are processed after marking.
1829   //
1830   //   * Discovery (may or may not be MT) is enabled at the start
1831   //     of an incremental evacuation pause.
1832   //   * References are processed near the end of a STW evacuation pause.
1833   //   * For both types of GC:
1834   //     * Discovery is atomic - i.e. not concurrent.
1835   //     * Reference discovery will not need a barrier.
1836 
1837   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1838 
1839   // Concurrent Mark ref processor
1840   _ref_processor_cm =
1841     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1842                            mt_processing,                                  // mt processing
1843                            ParallelGCThreads,                              // degree of mt processing
1844                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1845                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1846                            false,                                          // Reference discovery is not atomic
1847                            &_is_alive_closure_cm,                          // is alive closure
1848                            true);                                          // allow changes to number of processing threads
1849 
1850   // STW ref processor
1851   _ref_processor_stw =
1852     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1853                            mt_processing,                        // mt processing
1854                            ParallelGCThreads,                    // degree of mt processing
1855                            (ParallelGCThreads > 1),              // mt discovery
1856                            ParallelGCThreads,                    // degree of mt discovery
1857                            true,                                 // Reference discovery is atomic
1858                            &_is_alive_closure_stw,               // is alive closure
1859                            true);                                // allow changes to number of processing threads
1860 }
1861 
1862 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1863   return &_soft_ref_policy;
1864 }
1865 
1866 size_t G1CollectedHeap::capacity() const {
1867   return _hrm->length() * HeapRegion::GrainBytes;
1868 }
1869 
1870 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1871   return _hrm->total_free_bytes();
1872 }
1873 
1874 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1875   _hot_card_cache->drain(cl, worker_id);
1876 }
1877 
1878 // Computes the sum of the storage used by the various regions.
1879 size_t G1CollectedHeap::used() const {
1880   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1881   if (_archive_allocator != NULL) {
1882     result += _archive_allocator->used();
1883   }
1884   return result;
1885 }
1886 
1887 size_t G1CollectedHeap::used_unlocked() const {
1888   return _summary_bytes_used;
1889 }
1890 
1891 class SumUsedClosure: public HeapRegionClosure {
1892   size_t _used;
1893 public:
1894   SumUsedClosure() : _used(0) {}
1895   bool do_heap_region(HeapRegion* r) {
1896     _used += r->used();
1897     return false;
1898   }
1899   size_t result() { return _used; }
1900 };
1901 
1902 size_t G1CollectedHeap::recalculate_used() const {
1903   SumUsedClosure blk;
1904   heap_region_iterate(&blk);
1905   return blk.result();
1906 }
1907 
1908 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1909   switch (cause) {
1910     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1911     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1912     case GCCause::_wb_conc_mark:                        return true;
1913     default :                                           return false;
1914   }
1915 }
1916 
1917 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1918   switch (cause) {
1919     case GCCause::_g1_humongous_allocation: return true;
1920     case GCCause::_g1_periodic_collection:  return G1PeriodicGCInvokesConcurrent;
1921     case GCCause::_wb_breakpoint:           return true;
1922     default:                                return is_user_requested_concurrent_full_gc(cause);
1923   }
1924 }
1925 
1926 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
1927   if (policy()->force_upgrade_to_full()) {
1928     return true;
1929   } else if (should_do_concurrent_full_gc(_gc_cause)) {
1930     return false;
1931   } else if (has_regions_left_for_allocation()) {
1932     return false;
1933   } else {
1934     return true;
1935   }
1936 }
1937 
1938 #ifndef PRODUCT
1939 void G1CollectedHeap::allocate_dummy_regions() {
1940   // Let's fill up most of the region
1941   size_t word_size = HeapRegion::GrainWords - 1024;
1942   // And as a result the region we'll allocate will be humongous.
1943   guarantee(is_humongous(word_size), "sanity");
1944 
1945   // _filler_array_max_size is set to humongous object threshold
1946   // but temporarily change it to use CollectedHeap::fill_with_object().
1947   AutoModifyRestore<size_t> temporarily(_filler_array_max_size, word_size);
1948 
1949   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1950     // Let's use the existing mechanism for the allocation
1951     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1952     if (dummy_obj != NULL) {
1953       MemRegion mr(dummy_obj, word_size);
1954       CollectedHeap::fill_with_object(mr);
1955     } else {
1956       // If we can't allocate once, we probably cannot allocate
1957       // again. Let's get out of the loop.
1958       break;
1959     }
1960   }
1961 }
1962 #endif // !PRODUCT
1963 
1964 void G1CollectedHeap::increment_old_marking_cycles_started() {
1965   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1966          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1967          "Wrong marking cycle count (started: %d, completed: %d)",
1968          _old_marking_cycles_started, _old_marking_cycles_completed);
1969 
1970   _old_marking_cycles_started++;
1971 }
1972 
1973 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1974                                                              bool whole_heap_examined) {
1975   MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1976 
1977   // We assume that if concurrent == true, then the caller is a
1978   // concurrent thread that was joined the Suspendible Thread
1979   // Set. If there's ever a cheap way to check this, we should add an
1980   // assert here.
1981 
1982   // Given that this method is called at the end of a Full GC or of a
1983   // concurrent cycle, and those can be nested (i.e., a Full GC can
1984   // interrupt a concurrent cycle), the number of full collections
1985   // completed should be either one (in the case where there was no
1986   // nesting) or two (when a Full GC interrupted a concurrent cycle)
1987   // behind the number of full collections started.
1988 
1989   // This is the case for the inner caller, i.e. a Full GC.
1990   assert(concurrent ||
1991          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1992          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1993          "for inner caller (Full GC): _old_marking_cycles_started = %u "
1994          "is inconsistent with _old_marking_cycles_completed = %u",
1995          _old_marking_cycles_started, _old_marking_cycles_completed);
1996 
1997   // This is the case for the outer caller, i.e. the concurrent cycle.
1998   assert(!concurrent ||
1999          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2000          "for outer caller (concurrent cycle): "
2001          "_old_marking_cycles_started = %u "
2002          "is inconsistent with _old_marking_cycles_completed = %u",
2003          _old_marking_cycles_started, _old_marking_cycles_completed);
2004 
2005   _old_marking_cycles_completed += 1;
2006   if (whole_heap_examined) {
2007     // Signal that we have completed a visit to all live objects.
2008     record_whole_heap_examined_timestamp();
2009   }
2010 
2011   // We need to clear the "in_progress" flag in the CM thread before
2012   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2013   // is set) so that if a waiter requests another System.gc() it doesn't
2014   // incorrectly see that a marking cycle is still in progress.
2015   if (concurrent) {
2016     _cm_thread->set_idle();
2017   }
2018 
2019   // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2020   // for a full GC to finish that their wait is over.
2021   ml.notify_all();
2022 }
2023 
2024 void G1CollectedHeap::collect(GCCause::Cause cause) {
2025   try_collect(cause);
2026 }
2027 
2028 // Return true if (x < y) with allowance for wraparound.
2029 static bool gc_counter_less_than(uint x, uint y) {
2030   return (x - y) > (UINT_MAX/2);
2031 }
2032 
2033 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2034 // Macro so msg printing is format-checked.
2035 #define LOG_COLLECT_CONCURRENTLY(cause, ...)                            \
2036   do {                                                                  \
2037     LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt;                   \
2038     if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) {                     \
2039       ResourceMark rm; /* For thread name. */                           \
2040       LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2041       LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2042                                        Thread::current()->name(),       \
2043                                        GCCause::to_string(cause));      \
2044       LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__);                    \
2045     }                                                                   \
2046   } while (0)
2047 
2048 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2049   LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2050 
2051 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2052                                                uint gc_counter,
2053                                                uint old_marking_started_before) {
2054   assert_heap_not_locked();
2055   assert(should_do_concurrent_full_gc(cause),
2056          "Non-concurrent cause %s", GCCause::to_string(cause));
2057 
2058   for (uint i = 1; true; ++i) {
2059     // Try to schedule concurrent start evacuation pause that will
2060     // start a concurrent cycle.
2061     LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2062     VM_G1TryInitiateConcMark op(gc_counter,
2063                                 cause,
2064                                 policy()->max_pause_time_ms());
2065     VMThread::execute(&op);
2066 
2067     // Request is trivially finished.
2068     if (cause == GCCause::_g1_periodic_collection) {
2069       LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2070       return op.gc_succeeded();
2071     }
2072 
2073     // If VMOp skipped initiating concurrent marking cycle because
2074     // we're terminating, then we're done.
2075     if (op.terminating()) {
2076       LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2077       return false;
2078     }
2079 
2080     // Lock to get consistent set of values.
2081     uint old_marking_started_after;
2082     uint old_marking_completed_after;
2083     {
2084       MutexLocker ml(Heap_lock);
2085       // Update gc_counter for retrying VMOp if needed. Captured here to be
2086       // consistent with the values we use below for termination tests.  If
2087       // a retry is needed after a possible wait, and another collection
2088       // occurs in the meantime, it will cause our retry to be skipped and
2089       // we'll recheck for termination with updated conditions from that
2090       // more recent collection.  That's what we want, rather than having
2091       // our retry possibly perform an unnecessary collection.
2092       gc_counter = total_collections();
2093       old_marking_started_after = _old_marking_cycles_started;
2094       old_marking_completed_after = _old_marking_cycles_completed;
2095     }
2096 
2097     if (cause == GCCause::_wb_breakpoint) {
2098       if (op.gc_succeeded()) {
2099         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2100         return true;
2101       }
2102       // When _wb_breakpoint there can't be another cycle or deferred.
2103       assert(!op.cycle_already_in_progress(), "invariant");
2104       assert(!op.whitebox_attached(), "invariant");
2105       // Concurrent cycle attempt might have been cancelled by some other
2106       // collection, so retry.  Unlike other cases below, we want to retry
2107       // even if cancelled by a STW full collection, because we really want
2108       // to start a concurrent cycle.
2109       if (old_marking_started_before != old_marking_started_after) {
2110         LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2111         old_marking_started_before = old_marking_started_after;
2112       }
2113     } else if (!GCCause::is_user_requested_gc(cause)) {
2114       // For an "automatic" (not user-requested) collection, we just need to
2115       // ensure that progress is made.
2116       //
2117       // Request is finished if any of
2118       // (1) the VMOp successfully performed a GC,
2119       // (2) a concurrent cycle was already in progress,
2120       // (3) whitebox is controlling concurrent cycles,
2121       // (4) a new cycle was started (by this thread or some other), or
2122       // (5) a Full GC was performed.
2123       // Cases (4) and (5) are detected together by a change to
2124       // _old_marking_cycles_started.
2125       //
2126       // Note that (1) does not imply (4).  If we're still in the mixed
2127       // phase of an earlier concurrent collection, the request to make the
2128       // collection a concurrent start won't be honored.  If we don't check for
2129       // both conditions we'll spin doing back-to-back collections.
2130       if (op.gc_succeeded() ||
2131           op.cycle_already_in_progress() ||
2132           op.whitebox_attached() ||
2133           (old_marking_started_before != old_marking_started_after)) {
2134         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2135         return true;
2136       }
2137     } else {                    // User-requested GC.
2138       // For a user-requested collection, we want to ensure that a complete
2139       // full collection has been performed before returning, but without
2140       // waiting for more than needed.
2141 
2142       // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2143       // new cycle was started.  That's good, because it's not clear what we
2144       // should do otherwise.  Trying again just does back to back GCs.
2145       // Can't wait for someone else to start a cycle.  And returning fails
2146       // to meet the goal of ensuring a full collection was performed.
2147       assert(!op.gc_succeeded() ||
2148              (old_marking_started_before != old_marking_started_after),
2149              "invariant: succeeded %s, started before %u, started after %u",
2150              BOOL_TO_STR(op.gc_succeeded()),
2151              old_marking_started_before, old_marking_started_after);
2152 
2153       // Request is finished if a full collection (concurrent or stw)
2154       // was started after this request and has completed, e.g.
2155       // started_before < completed_after.
2156       if (gc_counter_less_than(old_marking_started_before,
2157                                old_marking_completed_after)) {
2158         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2159         return true;
2160       }
2161 
2162       if (old_marking_started_after != old_marking_completed_after) {
2163         // If there is an in-progress cycle (possibly started by us), then
2164         // wait for that cycle to complete, e.g.
2165         // while completed_now < started_after.
2166         LOG_COLLECT_CONCURRENTLY(cause, "wait");
2167         MonitorLocker ml(G1OldGCCount_lock);
2168         while (gc_counter_less_than(_old_marking_cycles_completed,
2169                                     old_marking_started_after)) {
2170           ml.wait();
2171         }
2172         // Request is finished if the collection we just waited for was
2173         // started after this request.
2174         if (old_marking_started_before != old_marking_started_after) {
2175           LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2176           return true;
2177         }
2178       }
2179 
2180       // If VMOp was successful then it started a new cycle that the above
2181       // wait &etc should have recognized as finishing this request.  This
2182       // differs from a non-user-request, where gc_succeeded does not imply
2183       // a new cycle was started.
2184       assert(!op.gc_succeeded(), "invariant");
2185 
2186       if (op.cycle_already_in_progress()) {
2187         // If VMOp failed because a cycle was already in progress, it
2188         // is now complete.  But it didn't finish this user-requested
2189         // GC, so try again.
2190         LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2191         continue;
2192       } else if (op.whitebox_attached()) {
2193         // If WhiteBox wants control, wait for notification of a state
2194         // change in the controller, then try again.  Don't wait for
2195         // release of control, since collections may complete while in
2196         // control.  Note: This won't recognize a STW full collection
2197         // while waiting; we can't wait on multiple monitors.
2198         LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2199         MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2200         if (ConcurrentGCBreakpoints::is_controlled()) {
2201           ml.wait();
2202         }
2203         continue;
2204       }
2205     }
2206 
2207     // Collection failed and should be retried.
2208     assert(op.transient_failure(), "invariant");
2209 
2210     if (GCLocker::is_active_and_needs_gc()) {
2211       // If GCLocker is active, wait until clear before retrying.
2212       LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2213       GCLocker::stall_until_clear();
2214     }
2215 
2216     LOG_COLLECT_CONCURRENTLY(cause, "retry");
2217   }
2218 }
2219 
2220 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2221   assert_heap_not_locked();
2222 
2223   // Lock to get consistent set of values.
2224   uint gc_count_before;
2225   uint full_gc_count_before;
2226   uint old_marking_started_before;
2227   {
2228     MutexLocker ml(Heap_lock);
2229     gc_count_before = total_collections();
2230     full_gc_count_before = total_full_collections();
2231     old_marking_started_before = _old_marking_cycles_started;
2232   }
2233 
2234   if (should_do_concurrent_full_gc(cause)) {
2235     return try_collect_concurrently(cause,
2236                                     gc_count_before,
2237                                     old_marking_started_before);
2238   } else if (GCLocker::should_discard(cause, gc_count_before)) {
2239     // Indicate failure to be consistent with VMOp failure due to
2240     // another collection slipping in after our gc_count but before
2241     // our request is processed.
2242     return false;
2243   } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2244              DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2245 
2246     // Schedule a standard evacuation pause. We're setting word_size
2247     // to 0 which means that we are not requesting a post-GC allocation.
2248     VM_G1CollectForAllocation op(0,     /* word_size */
2249                                  gc_count_before,
2250                                  cause,
2251                                  policy()->max_pause_time_ms());
2252     VMThread::execute(&op);
2253     return op.gc_succeeded();
2254   } else {
2255     // Schedule a Full GC.
2256     VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2257     VMThread::execute(&op);
2258     return op.gc_succeeded();
2259   }
2260 }
2261 
2262 bool G1CollectedHeap::is_in(const void* p) const {
2263   if (_hrm->reserved().contains(p)) {
2264     // Given that we know that p is in the reserved space,
2265     // heap_region_containing() should successfully
2266     // return the containing region.
2267     HeapRegion* hr = heap_region_containing(p);
2268     return hr->is_in(p);
2269   } else {
2270     return false;
2271   }
2272 }
2273 
2274 #ifdef ASSERT
2275 bool G1CollectedHeap::is_in_exact(const void* p) const {
2276   bool contains = reserved_region().contains(p);
2277   bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2278   if (contains && available) {
2279     return true;
2280   } else {
2281     return false;
2282   }
2283 }
2284 #endif
2285 
2286 // Iteration functions.
2287 
2288 // Iterates an ObjectClosure over all objects within a HeapRegion.
2289 
2290 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2291   ObjectClosure* _cl;
2292 public:
2293   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2294   bool do_heap_region(HeapRegion* r) {
2295     if (!r->is_continues_humongous()) {
2296       r->object_iterate(_cl);
2297     }
2298     return false;
2299   }
2300 };
2301 
2302 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2303   IterateObjectClosureRegionClosure blk(cl);
2304   heap_region_iterate(&blk);
2305 }
2306 
2307 class G1ParallelObjectIterator : public ParallelObjectIterator {
2308 private:
2309   G1CollectedHeap*  _heap;
2310   HeapRegionClaimer _claimer;
2311 
2312 public:
2313   G1ParallelObjectIterator(uint thread_num) :
2314       _heap(G1CollectedHeap::heap()),
2315       _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2316 
2317   virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2318     _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2319   }
2320 };
2321 
2322 ParallelObjectIterator* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2323   return new G1ParallelObjectIterator(thread_num);
2324 }
2325 
2326 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2327   IterateObjectClosureRegionClosure blk(cl);
2328   heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2329 }
2330 
2331 void G1CollectedHeap::keep_alive(oop obj) {
2332   G1BarrierSet::enqueue(obj);
2333 }
2334 
2335 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2336   _hrm->iterate(cl);
2337 }
2338 
2339 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2340                                                                  HeapRegionClaimer *hrclaimer,
2341                                                                  uint worker_id) const {
2342   _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2343 }
2344 
2345 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2346                                                          HeapRegionClaimer *hrclaimer) const {
2347   _hrm->par_iterate(cl, hrclaimer, 0);
2348 }
2349 
2350 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2351   _collection_set.iterate(cl);
2352 }
2353 
2354 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2355   _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2356 }
2357 
2358 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2359   _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2360 }
2361 
2362 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2363   HeapRegion* hr = heap_region_containing(addr);
2364   return hr->block_start(addr);
2365 }
2366 
2367 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2368   HeapRegion* hr = heap_region_containing(addr);
2369   return hr->block_is_obj(addr);
2370 }
2371 
2372 bool G1CollectedHeap::supports_tlab_allocation() const {
2373   return true;
2374 }
2375 
2376 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2377   return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2378 }
2379 
2380 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2381   return _eden.length() * HeapRegion::GrainBytes;
2382 }
2383 
2384 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2385 // must be equal to the humongous object limit.
2386 size_t G1CollectedHeap::max_tlab_size() const {
2387   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2388 }
2389 
2390 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2391   return _allocator->unsafe_max_tlab_alloc();
2392 }
2393 
2394 size_t G1CollectedHeap::max_capacity() const {
2395   return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2396 }
2397 
2398 size_t G1CollectedHeap::max_reserved_capacity() const {
2399   return _hrm->max_length() * HeapRegion::GrainBytes;
2400 }
2401 
2402 void G1CollectedHeap::deduplicate_string(oop str) {
2403   assert(java_lang_String::is_instance(str), "invariant");
2404 
2405   if (G1StringDedup::is_enabled()) {
2406     G1StringDedup::deduplicate(str);
2407   }
2408 }
2409 
2410 void G1CollectedHeap::prepare_for_verify() {
2411   _verifier->prepare_for_verify();
2412 }
2413 
2414 void G1CollectedHeap::verify(VerifyOption vo) {
2415   _verifier->verify(vo);
2416 }
2417 
2418 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2419   return true;
2420 }
2421 
2422 bool G1CollectedHeap::is_heterogeneous_heap() const {
2423   return G1Arguments::is_heterogeneous_heap();
2424 }
2425 
2426 class PrintRegionClosure: public HeapRegionClosure {
2427   outputStream* _st;
2428 public:
2429   PrintRegionClosure(outputStream* st) : _st(st) {}
2430   bool do_heap_region(HeapRegion* r) {
2431     r->print_on(_st);
2432     return false;
2433   }
2434 };
2435 
2436 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2437                                        const HeapRegion* hr,
2438                                        const VerifyOption vo) const {
2439   switch (vo) {
2440   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2441   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2442   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2443   default:                            ShouldNotReachHere();
2444   }
2445   return false; // keep some compilers happy
2446 }
2447 
2448 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2449                                        const VerifyOption vo) const {
2450   switch (vo) {
2451   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2452   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2453   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2454   default:                            ShouldNotReachHere();
2455   }
2456   return false; // keep some compilers happy
2457 }
2458 
2459 void G1CollectedHeap::print_heap_regions() const {
2460   LogTarget(Trace, gc, heap, region) lt;
2461   if (lt.is_enabled()) {
2462     LogStream ls(lt);
2463     print_regions_on(&ls);
2464   }
2465 }
2466 
2467 void G1CollectedHeap::print_on(outputStream* st) const {
2468   st->print(" %-20s", "garbage-first heap");
2469   if (_hrm != NULL) {
2470     st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2471               capacity()/K, used_unlocked()/K);
2472     st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2473               p2i(_hrm->reserved().start()),
2474               p2i(_hrm->reserved().end()));
2475   }
2476   st->cr();
2477   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2478   uint young_regions = young_regions_count();
2479   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2480             (size_t) young_regions * HeapRegion::GrainBytes / K);
2481   uint survivor_regions = survivor_regions_count();
2482   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2483             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2484   st->cr();
2485   if (_numa->is_enabled()) {
2486     uint num_nodes = _numa->num_active_nodes();
2487     st->print("  remaining free region(s) on each NUMA node: ");
2488     const int* node_ids = _numa->node_ids();
2489     for (uint node_index = 0; node_index < num_nodes; node_index++) {
2490       uint num_free_regions = (_hrm != NULL ? _hrm->num_free_regions(node_index) : 0);
2491       st->print("%d=%u ", node_ids[node_index], num_free_regions);
2492     }
2493     st->cr();
2494   }
2495   MetaspaceUtils::print_on(st);
2496 }
2497 
2498 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2499   if (_hrm == NULL) {
2500     return;
2501   }
2502 
2503   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2504                "HS=humongous(starts), HC=humongous(continues), "
2505                "CS=collection set, F=free, "
2506                "OA=open archive, CA=closed archive, "
2507                "TAMS=top-at-mark-start (previous, next)");
2508   PrintRegionClosure blk(st);
2509   heap_region_iterate(&blk);
2510 }
2511 
2512 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2513   print_on(st);
2514 
2515   // Print the per-region information.
2516   if (_hrm != NULL) {
2517     st->cr();
2518     print_regions_on(st);
2519   }
2520 }
2521 
2522 void G1CollectedHeap::print_on_error(outputStream* st) const {
2523   this->CollectedHeap::print_on_error(st);
2524 
2525   if (_cm != NULL) {
2526     st->cr();
2527     _cm->print_on_error(st);
2528   }
2529 }
2530 
2531 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2532   workers()->threads_do(tc);
2533   tc->do_thread(_cm_thread);
2534   _cm->threads_do(tc);
2535   _cr->threads_do(tc);
2536   tc->do_thread(_service_thread);
2537   if (G1StringDedup::is_enabled()) {
2538     G1StringDedup::threads_do(tc);
2539   }
2540 }
2541 
2542 void G1CollectedHeap::print_tracing_info() const {
2543   rem_set()->print_summary_info();
2544   concurrent_mark()->print_summary_info();
2545 }
2546 
2547 #ifndef PRODUCT
2548 // Helpful for debugging RSet issues.
2549 
2550 class PrintRSetsClosure : public HeapRegionClosure {
2551 private:
2552   const char* _msg;
2553   size_t _occupied_sum;
2554 
2555 public:
2556   bool do_heap_region(HeapRegion* r) {
2557     HeapRegionRemSet* hrrs = r->rem_set();
2558     size_t occupied = hrrs->occupied();
2559     _occupied_sum += occupied;
2560 
2561     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2562     if (occupied == 0) {
2563       tty->print_cr("  RSet is empty");
2564     } else {
2565       hrrs->print();
2566     }
2567     tty->print_cr("----------");
2568     return false;
2569   }
2570 
2571   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2572     tty->cr();
2573     tty->print_cr("========================================");
2574     tty->print_cr("%s", msg);
2575     tty->cr();
2576   }
2577 
2578   ~PrintRSetsClosure() {
2579     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2580     tty->print_cr("========================================");
2581     tty->cr();
2582   }
2583 };
2584 
2585 void G1CollectedHeap::print_cset_rsets() {
2586   PrintRSetsClosure cl("Printing CSet RSets");
2587   collection_set_iterate_all(&cl);
2588 }
2589 
2590 void G1CollectedHeap::print_all_rsets() {
2591   PrintRSetsClosure cl("Printing All RSets");;
2592   heap_region_iterate(&cl);
2593 }
2594 #endif // PRODUCT
2595 
2596 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2597   return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2598 }
2599 
2600 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2601 
2602   size_t eden_used_bytes = _eden.used_bytes();
2603   size_t survivor_used_bytes = _survivor.used_bytes();
2604   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2605 
2606   size_t eden_capacity_bytes =
2607     (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2608 
2609   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2610   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2611                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2612 }
2613 
2614 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2615   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2616                        stats->unused(), stats->used(), stats->region_end_waste(),
2617                        stats->regions_filled(), stats->direct_allocated(),
2618                        stats->failure_used(), stats->failure_waste());
2619 }
2620 
2621 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2622   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2623   gc_tracer->report_gc_heap_summary(when, heap_summary);
2624 
2625   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2626   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2627 }
2628 
2629 void G1CollectedHeap::gc_prologue(bool full) {
2630   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2631 
2632   // This summary needs to be printed before incrementing total collections.
2633   rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2634 
2635   // Update common counters.
2636   increment_total_collections(full /* full gc */);
2637   if (full || collector_state()->in_concurrent_start_gc()) {
2638     increment_old_marking_cycles_started();
2639   }
2640 
2641   // Fill TLAB's and such
2642   {
2643     Ticks start = Ticks::now();
2644     ensure_parsability(true);
2645     Tickspan dt = Ticks::now() - start;
2646     phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS);
2647   }
2648 
2649   if (!full) {
2650     // Flush dirty card queues to qset, so later phases don't need to account
2651     // for partially filled per-thread queues and such.  Not needed for full
2652     // collections, which ignore those logs.
2653     Ticks start = Ticks::now();
2654     G1BarrierSet::dirty_card_queue_set().concatenate_logs();
2655     Tickspan dt = Ticks::now() - start;
2656     phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS);
2657   }
2658 }
2659 
2660 void G1CollectedHeap::gc_epilogue(bool full) {
2661   // Update common counters.
2662   if (full) {
2663     // Update the number of full collections that have been completed.
2664     increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2665   }
2666 
2667   // We are at the end of the GC. Total collections has already been increased.
2668   rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2669 
2670   // FIXME: what is this about?
2671   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2672   // is set.
2673 #if COMPILER2_OR_JVMCI
2674   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2675 #endif
2676 
2677   double start = os::elapsedTime();
2678   resize_all_tlabs();
2679   phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2680 
2681   MemoryService::track_memory_usage();
2682   // We have just completed a GC. Update the soft reference
2683   // policy with the new heap occupancy
2684   Universe::update_heap_info_at_gc();
2685 
2686   // Print NUMA statistics.
2687   _numa->print_statistics();
2688 
2689   _collection_pause_end = Ticks::now();
2690 }
2691 
2692 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2693   LogTarget(Trace, gc, heap, verify) lt;
2694 
2695   if (lt.is_enabled()) {
2696     LogStream ls(lt);
2697     // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2698     G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2699     heap_region_iterate(&cl);
2700   }
2701 }
2702 
2703 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2704                                                uint gc_count_before,
2705                                                bool* succeeded,
2706                                                GCCause::Cause gc_cause) {
2707   assert_heap_not_locked_and_not_at_safepoint();
2708   VM_G1CollectForAllocation op(word_size,
2709                                gc_count_before,
2710                                gc_cause,
2711                                policy()->max_pause_time_ms());
2712   VMThread::execute(&op);
2713 
2714   HeapWord* result = op.result();
2715   bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2716   assert(result == NULL || ret_succeeded,
2717          "the result should be NULL if the VM did not succeed");
2718   *succeeded = ret_succeeded;
2719 
2720   assert_heap_not_locked();
2721   return result;
2722 }
2723 
2724 void G1CollectedHeap::do_concurrent_mark() {
2725   MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2726   if (!_cm_thread->in_progress()) {
2727     _cm_thread->set_started();
2728     CGC_lock->notify();
2729   }
2730 }
2731 
2732 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2733   // We don't nominate objects with many remembered set entries, on
2734   // the assumption that such objects are likely still live.
2735   HeapRegionRemSet* rem_set = r->rem_set();
2736 
2737   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2738          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2739          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2740 }
2741 
2742 #ifndef PRODUCT
2743 void G1CollectedHeap::verify_region_attr_remset_update() {
2744   class VerifyRegionAttrRemSet : public HeapRegionClosure {
2745   public:
2746     virtual bool do_heap_region(HeapRegion* r) {
2747       G1CollectedHeap* g1h = G1CollectedHeap::heap();
2748       bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2749       assert(r->rem_set()->is_tracked() == needs_remset_update,
2750              "Region %u remset tracking status (%s) different to region attribute (%s)",
2751              r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2752       return false;
2753     }
2754   } cl;
2755   heap_region_iterate(&cl);
2756 }
2757 #endif
2758 
2759 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2760   public:
2761     bool do_heap_region(HeapRegion* hr) {
2762       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2763         hr->verify_rem_set();
2764       }
2765       return false;
2766     }
2767 };
2768 
2769 uint G1CollectedHeap::num_task_queues() const {
2770   return _task_queues->size();
2771 }
2772 
2773 #if TASKQUEUE_STATS
2774 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2775   st->print_raw_cr("GC Task Stats");
2776   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2777   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2778 }
2779 
2780 void G1CollectedHeap::print_taskqueue_stats() const {
2781   if (!log_is_enabled(Trace, gc, task, stats)) {
2782     return;
2783   }
2784   Log(gc, task, stats) log;
2785   ResourceMark rm;
2786   LogStream ls(log.trace());
2787   outputStream* st = &ls;
2788 
2789   print_taskqueue_stats_hdr(st);
2790 
2791   TaskQueueStats totals;
2792   const uint n = num_task_queues();
2793   for (uint i = 0; i < n; ++i) {
2794     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2795     totals += task_queue(i)->stats;
2796   }
2797   st->print_raw("tot "); totals.print(st); st->cr();
2798 
2799   DEBUG_ONLY(totals.verify());
2800 }
2801 
2802 void G1CollectedHeap::reset_taskqueue_stats() {
2803   const uint n = num_task_queues();
2804   for (uint i = 0; i < n; ++i) {
2805     task_queue(i)->stats.reset();
2806   }
2807 }
2808 #endif // TASKQUEUE_STATS
2809 
2810 void G1CollectedHeap::wait_for_root_region_scanning() {
2811   double scan_wait_start = os::elapsedTime();
2812   // We have to wait until the CM threads finish scanning the
2813   // root regions as it's the only way to ensure that all the
2814   // objects on them have been correctly scanned before we start
2815   // moving them during the GC.
2816   bool waited = _cm->root_regions()->wait_until_scan_finished();
2817   double wait_time_ms = 0.0;
2818   if (waited) {
2819     double scan_wait_end = os::elapsedTime();
2820     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2821   }
2822   phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2823 }
2824 
2825 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2826 private:
2827   G1HRPrinter* _hr_printer;
2828 public:
2829   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2830 
2831   virtual bool do_heap_region(HeapRegion* r) {
2832     _hr_printer->cset(r);
2833     return false;
2834   }
2835 };
2836 
2837 void G1CollectedHeap::start_new_collection_set() {
2838   double start = os::elapsedTime();
2839 
2840   collection_set()->start_incremental_building();
2841 
2842   clear_region_attr();
2843 
2844   guarantee(_eden.length() == 0, "eden should have been cleared");
2845   policy()->transfer_survivors_to_cset(survivor());
2846 
2847   // We redo the verification but now wrt to the new CSet which
2848   // has just got initialized after the previous CSet was freed.
2849   _cm->verify_no_collection_set_oops();
2850 
2851   phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2852 }
2853 
2854 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2855 
2856   _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2857   evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2858                                             collection_set()->optional_region_length());
2859 
2860   _cm->verify_no_collection_set_oops();
2861 
2862   if (_hr_printer.is_active()) {
2863     G1PrintCollectionSetClosure cl(&_hr_printer);
2864     _collection_set.iterate(&cl);
2865     _collection_set.iterate_optional(&cl);
2866   }
2867 }
2868 
2869 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2870   if (collector_state()->in_concurrent_start_gc()) {
2871     return G1HeapVerifier::G1VerifyConcurrentStart;
2872   } else if (collector_state()->in_young_only_phase()) {
2873     return G1HeapVerifier::G1VerifyYoungNormal;
2874   } else {
2875     return G1HeapVerifier::G1VerifyMixed;
2876   }
2877 }
2878 
2879 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2880   if (VerifyRememberedSets) {
2881     log_info(gc, verify)("[Verifying RemSets before GC]");
2882     VerifyRegionRemSetClosure v_cl;
2883     heap_region_iterate(&v_cl);
2884   }
2885   _verifier->verify_before_gc(type);
2886   _verifier->check_bitmaps("GC Start");
2887   verify_numa_regions("GC Start");
2888 }
2889 
2890 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2891   if (VerifyRememberedSets) {
2892     log_info(gc, verify)("[Verifying RemSets after GC]");
2893     VerifyRegionRemSetClosure v_cl;
2894     heap_region_iterate(&v_cl);
2895   }
2896   _verifier->verify_after_gc(type);
2897   _verifier->check_bitmaps("GC End");
2898   verify_numa_regions("GC End");
2899 }
2900 
2901 void G1CollectedHeap::expand_heap_after_young_collection(){
2902   size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2903   if (expand_bytes > 0) {
2904     // No need for an ergo logging here,
2905     // expansion_amount() does this when it returns a value > 0.
2906     double expand_ms;
2907     if (!expand(expand_bytes, _workers, &expand_ms)) {
2908       // We failed to expand the heap. Cannot do anything about it.
2909     }
2910     phase_times()->record_expand_heap_time(expand_ms);
2911   }
2912 }
2913 
2914 const char* G1CollectedHeap::young_gc_name() const {
2915   if (collector_state()->in_concurrent_start_gc()) {
2916     return "Pause Young (Concurrent Start)";
2917   } else if (collector_state()->in_young_only_phase()) {
2918     if (collector_state()->in_young_gc_before_mixed()) {
2919       return "Pause Young (Prepare Mixed)";
2920     } else {
2921       return "Pause Young (Normal)";
2922     }
2923   } else {
2924     return "Pause Young (Mixed)";
2925   }
2926 }
2927 
2928 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2929   assert_at_safepoint_on_vm_thread();
2930   guarantee(!is_gc_active(), "collection is not reentrant");
2931 
2932   if (GCLocker::check_active_before_gc()) {
2933     return false;
2934   }
2935 
2936   do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2937   if (should_upgrade_to_full_gc(gc_cause())) {
2938     log_info(gc, ergo)("Attempting maximally compacting collection");
2939     bool result = do_full_collection(false /* explicit gc */,
2940                                      true /* clear_all_soft_refs */);
2941     // do_full_collection only fails if blocked by GC locker, but
2942     // we've already checked for that above.
2943     assert(result, "invariant");
2944   }
2945   return true;
2946 }
2947 
2948 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2949   GCIdMark gc_id_mark;
2950 
2951   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2952   ResourceMark rm;
2953 
2954   policy()->note_gc_start();
2955 
2956   _gc_timer_stw->register_gc_start();
2957   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2958 
2959   wait_for_root_region_scanning();
2960 
2961   print_heap_before_gc();
2962   print_heap_regions();
2963   trace_heap_before_gc(_gc_tracer_stw);
2964 
2965   _verifier->verify_region_sets_optional();
2966   _verifier->verify_dirty_young_regions();
2967 
2968   // We should not be doing concurrent start unless the concurrent mark thread is running
2969   if (!_cm_thread->should_terminate()) {
2970     // This call will decide whether this pause is a concurrent start
2971     // pause. If it is, in_concurrent_start_gc() will return true
2972     // for the duration of this pause.
2973     policy()->decide_on_conc_mark_initiation();
2974   }
2975 
2976   // We do not allow concurrent start to be piggy-backed on a mixed GC.
2977   assert(!collector_state()->in_concurrent_start_gc() ||
2978          collector_state()->in_young_only_phase(), "sanity");
2979   // We also do not allow mixed GCs during marking.
2980   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2981 
2982   // Record whether this pause is a concurrent start. When the current
2983   // thread has completed its logging output and it's safe to signal
2984   // the CM thread, the flag's value in the policy has been reset.
2985   bool should_start_conc_mark = collector_state()->in_concurrent_start_gc();
2986   if (should_start_conc_mark) {
2987     _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2988   }
2989 
2990   // Inner scope for scope based logging, timers, and stats collection
2991   {
2992     G1EvacuationInfo evacuation_info;
2993 
2994     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2995 
2996     GCTraceCPUTime tcpu;
2997 
2998     GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
2999 
3000     uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3001                                                             workers()->active_workers(),
3002                                                             Threads::number_of_non_daemon_threads());
3003     active_workers = workers()->update_active_workers(active_workers);
3004     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3005 
3006     G1MonitoringScope ms(g1mm(),
3007                          false /* full_gc */,
3008                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3009 
3010     G1HeapTransition heap_transition(this);
3011 
3012     {
3013       IsGCActiveMark x;
3014 
3015       gc_prologue(false);
3016 
3017       G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3018       verify_before_young_collection(verify_type);
3019 
3020       {
3021         // The elapsed time induced by the start time below deliberately elides
3022         // the possible verification above.
3023         double sample_start_time_sec = os::elapsedTime();
3024 
3025         // Please see comment in g1CollectedHeap.hpp and
3026         // G1CollectedHeap::ref_processing_init() to see how
3027         // reference processing currently works in G1.
3028         _ref_processor_stw->enable_discovery();
3029 
3030         // We want to temporarily turn off discovery by the
3031         // CM ref processor, if necessary, and turn it back on
3032         // on again later if we do. Using a scoped
3033         // NoRefDiscovery object will do this.
3034         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3035 
3036         policy()->record_collection_pause_start(sample_start_time_sec);
3037 
3038         // Forget the current allocation region (we might even choose it to be part
3039         // of the collection set!).
3040         _allocator->release_mutator_alloc_regions();
3041 
3042         calculate_collection_set(evacuation_info, target_pause_time_ms);
3043 
3044         G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3045         G1ParScanThreadStateSet per_thread_states(this,
3046                                                   &rdcqs,
3047                                                   workers()->active_workers(),
3048                                                   collection_set()->young_region_length(),
3049                                                   collection_set()->optional_region_length());
3050         pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3051 
3052         // Actually do the work...
3053         evacuate_initial_collection_set(&per_thread_states);
3054 
3055         if (_collection_set.optional_region_length() != 0) {
3056           evacuate_optional_collection_set(&per_thread_states);
3057         }
3058         post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3059 
3060         start_new_collection_set();
3061 
3062         _survivor_evac_stats.adjust_desired_plab_sz();
3063         _old_evac_stats.adjust_desired_plab_sz();
3064 
3065         if (should_start_conc_mark) {
3066           // We have to do this before we notify the CM threads that
3067           // they can start working to make sure that all the
3068           // appropriate initialization is done on the CM object.
3069           concurrent_mark()->post_concurrent_start();
3070           // Note that we don't actually trigger the CM thread at
3071           // this point. We do that later when we're sure that
3072           // the current thread has completed its logging output.
3073         }
3074 
3075         allocate_dummy_regions();
3076 
3077         _allocator->init_mutator_alloc_regions();
3078 
3079         expand_heap_after_young_collection();
3080 
3081         double sample_end_time_sec = os::elapsedTime();
3082         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3083         policy()->record_collection_pause_end(pause_time_ms);
3084       }
3085 
3086       verify_after_young_collection(verify_type);
3087 
3088       gc_epilogue(false);
3089     }
3090 
3091     // Print the remainder of the GC log output.
3092     if (evacuation_failed()) {
3093       log_info(gc)("To-space exhausted");
3094     }
3095 
3096     policy()->print_phases();
3097     heap_transition.print();
3098 
3099     _hrm->verify_optional();
3100     _verifier->verify_region_sets_optional();
3101 
3102     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3103     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3104 
3105     print_heap_after_gc();
3106     print_heap_regions();
3107     trace_heap_after_gc(_gc_tracer_stw);
3108 
3109     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3110     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3111     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3112     // before any GC notifications are raised.
3113     g1mm()->update_sizes();
3114 
3115     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3116     _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3117     _gc_timer_stw->register_gc_end();
3118     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3119   }
3120   // It should now be safe to tell the concurrent mark thread to start
3121   // without its logging output interfering with the logging output
3122   // that came from the pause.
3123 
3124   if (should_start_conc_mark) {
3125     // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3126     // thread(s) could be running concurrently with us. Make sure that anything
3127     // after this point does not assume that we are the only GC thread running.
3128     // Note: of course, the actual marking work will not start until the safepoint
3129     // itself is released in SuspendibleThreadSet::desynchronize().
3130     do_concurrent_mark();
3131     ConcurrentGCBreakpoints::notify_idle_to_active();
3132   }
3133 }
3134 
3135 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3136   G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3137   workers()->run_task(&rsfp_task);
3138 }
3139 
3140 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3141   double remove_self_forwards_start = os::elapsedTime();
3142 
3143   remove_self_forwarding_pointers(rdcqs);
3144   _preserved_marks_set.restore(workers());
3145 
3146   phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3147 }
3148 
3149 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3150   if (!_evacuation_failed) {
3151     _evacuation_failed = true;
3152   }
3153 
3154   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3155   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3156 }
3157 
3158 bool G1ParEvacuateFollowersClosure::offer_termination() {
3159   EventGCPhaseParallel event;
3160   G1ParScanThreadState* const pss = par_scan_state();
3161   start_term_time();
3162   const bool res = terminator()->offer_termination();
3163   end_term_time();
3164   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3165   return res;
3166 }
3167 
3168 void G1ParEvacuateFollowersClosure::do_void() {
3169   EventGCPhaseParallel event;
3170   G1ParScanThreadState* const pss = par_scan_state();
3171   pss->trim_queue();
3172   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3173   do {
3174     EventGCPhaseParallel event;
3175     pss->steal_and_trim_queue(queues());
3176     event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3177   } while (!offer_termination());
3178 }
3179 
3180 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3181                                         bool class_unloading_occurred) {
3182   uint num_workers = workers()->active_workers();
3183   G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3184   workers()->run_task(&unlink_task);
3185 }
3186 
3187 // Clean string dedup data structures.
3188 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3189 // record the durations of the phases. Hence the almost-copy.
3190 class G1StringDedupCleaningTask : public AbstractGangTask {
3191   BoolObjectClosure* _is_alive;
3192   OopClosure* _keep_alive;
3193   G1GCPhaseTimes* _phase_times;
3194 
3195 public:
3196   G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3197                             OopClosure* keep_alive,
3198                             G1GCPhaseTimes* phase_times) :
3199     AbstractGangTask("Partial Cleaning Task"),
3200     _is_alive(is_alive),
3201     _keep_alive(keep_alive),
3202     _phase_times(phase_times)
3203   {
3204     assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3205     StringDedup::gc_prologue(true);
3206   }
3207 
3208   ~G1StringDedupCleaningTask() {
3209     StringDedup::gc_epilogue();
3210   }
3211 
3212   void work(uint worker_id) {
3213     StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3214     {
3215       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3216       StringDedupQueue::unlink_or_oops_do(&cl);
3217     }
3218     {
3219       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3220       StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3221     }
3222   }
3223 };
3224 
3225 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3226                                             OopClosure* keep_alive,
3227                                             G1GCPhaseTimes* phase_times) {
3228   G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3229   workers()->run_task(&cl);
3230 }
3231 
3232 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3233  private:
3234   G1RedirtyCardsQueueSet* _qset;
3235   G1CollectedHeap* _g1h;
3236   BufferNode* volatile _nodes;
3237 
3238   void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3239     size_t buffer_size = _qset->buffer_size();
3240     BufferNode* next = Atomic::load(&_nodes);
3241     while (next != NULL) {
3242       BufferNode* node = next;
3243       next = Atomic::cmpxchg(&_nodes, node, node->next());
3244       if (next == node) {
3245         cl->apply_to_buffer(node, buffer_size, worker_id);
3246         next = node->next();
3247       }
3248     }
3249   }
3250 
3251  public:
3252   G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3253     AbstractGangTask("Redirty Cards"),
3254     _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3255 
3256   virtual void work(uint worker_id) {
3257     G1GCPhaseTimes* p = _g1h->phase_times();
3258     G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3259 
3260     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3261     par_apply(&cl, worker_id);
3262 
3263     p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3264   }
3265 };
3266 
3267 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3268   double redirty_logged_cards_start = os::elapsedTime();
3269 
3270   G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3271   workers()->run_task(&redirty_task);
3272 
3273   G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3274   dcq.merge_bufferlists(rdcqs);
3275 
3276   phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3277 }
3278 
3279 // Weak Reference Processing support
3280 
3281 bool G1STWIsAliveClosure::do_object_b(oop p) {
3282   // An object is reachable if it is outside the collection set,
3283   // or is inside and copied.
3284   return !_g1h->is_in_cset(p) || p->is_forwarded();
3285 }
3286 
3287 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3288   assert(obj != NULL, "must not be NULL");
3289   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3290   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3291   // may falsely indicate that this is not the case here: however the collection set only
3292   // contains old regions when concurrent mark is not running.
3293   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3294 }
3295 
3296 // Non Copying Keep Alive closure
3297 class G1KeepAliveClosure: public OopClosure {
3298   G1CollectedHeap*_g1h;
3299 public:
3300   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3301   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3302   void do_oop(oop* p) {
3303     oop obj = *p;
3304     assert(obj != NULL, "the caller should have filtered out NULL values");
3305 
3306     const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3307     if (!region_attr.is_in_cset_or_humongous()) {
3308       return;
3309     }
3310     if (region_attr.is_in_cset()) {
3311       assert( obj->is_forwarded(), "invariant" );
3312       *p = obj->forwardee();
3313     } else {
3314       assert(!obj->is_forwarded(), "invariant" );
3315       assert(region_attr.is_humongous(),
3316              "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3317      _g1h->set_humongous_is_live(obj);
3318     }
3319   }
3320 };
3321 
3322 // Copying Keep Alive closure - can be called from both
3323 // serial and parallel code as long as different worker
3324 // threads utilize different G1ParScanThreadState instances
3325 // and different queues.
3326 
3327 class G1CopyingKeepAliveClosure: public OopClosure {
3328   G1CollectedHeap*         _g1h;
3329   G1ParScanThreadState*    _par_scan_state;
3330 
3331 public:
3332   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3333                             G1ParScanThreadState* pss):
3334     _g1h(g1h),
3335     _par_scan_state(pss)
3336   {}
3337 
3338   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3339   virtual void do_oop(      oop* p) { do_oop_work(p); }
3340 
3341   template <class T> void do_oop_work(T* p) {
3342     oop obj = RawAccess<>::oop_load(p);
3343 
3344     if (_g1h->is_in_cset_or_humongous(obj)) {
3345       // If the referent object has been forwarded (either copied
3346       // to a new location or to itself in the event of an
3347       // evacuation failure) then we need to update the reference
3348       // field and, if both reference and referent are in the G1
3349       // heap, update the RSet for the referent.
3350       //
3351       // If the referent has not been forwarded then we have to keep
3352       // it alive by policy. Therefore we have copy the referent.
3353       //
3354       // When the queue is drained (after each phase of reference processing)
3355       // the object and it's followers will be copied, the reference field set
3356       // to point to the new location, and the RSet updated.
3357       _par_scan_state->push_on_queue(ScannerTask(p));
3358     }
3359   }
3360 };
3361 
3362 // Serial drain queue closure. Called as the 'complete_gc'
3363 // closure for each discovered list in some of the
3364 // reference processing phases.
3365 
3366 class G1STWDrainQueueClosure: public VoidClosure {
3367 protected:
3368   G1CollectedHeap* _g1h;
3369   G1ParScanThreadState* _par_scan_state;
3370 
3371   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3372 
3373 public:
3374   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3375     _g1h(g1h),
3376     _par_scan_state(pss)
3377   { }
3378 
3379   void do_void() {
3380     G1ParScanThreadState* const pss = par_scan_state();
3381     pss->trim_queue();
3382   }
3383 };
3384 
3385 // Parallel Reference Processing closures
3386 
3387 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3388 // processing during G1 evacuation pauses.
3389 
3390 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3391 private:
3392   G1CollectedHeap*          _g1h;
3393   G1ParScanThreadStateSet*  _pss;
3394   G1ScannerTasksQueueSet*   _queues;
3395   WorkGang*                 _workers;
3396 
3397 public:
3398   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3399                            G1ParScanThreadStateSet* per_thread_states,
3400                            WorkGang* workers,
3401                            G1ScannerTasksQueueSet *task_queues) :
3402     _g1h(g1h),
3403     _pss(per_thread_states),
3404     _queues(task_queues),
3405     _workers(workers)
3406   {
3407     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3408   }
3409 
3410   // Executes the given task using concurrent marking worker threads.
3411   virtual void execute(ProcessTask& task, uint ergo_workers);
3412 };
3413 
3414 // Gang task for possibly parallel reference processing
3415 
3416 class G1STWRefProcTaskProxy: public AbstractGangTask {
3417   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3418   ProcessTask&     _proc_task;
3419   G1CollectedHeap* _g1h;
3420   G1ParScanThreadStateSet* _pss;
3421   G1ScannerTasksQueueSet* _task_queues;
3422   TaskTerminator* _terminator;
3423 
3424 public:
3425   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3426                         G1CollectedHeap* g1h,
3427                         G1ParScanThreadStateSet* per_thread_states,
3428                         G1ScannerTasksQueueSet *task_queues,
3429                         TaskTerminator* terminator) :
3430     AbstractGangTask("Process reference objects in parallel"),
3431     _proc_task(proc_task),
3432     _g1h(g1h),
3433     _pss(per_thread_states),
3434     _task_queues(task_queues),
3435     _terminator(terminator)
3436   {}
3437 
3438   virtual void work(uint worker_id) {
3439     // The reference processing task executed by a single worker.
3440     ResourceMark rm;
3441 
3442     G1STWIsAliveClosure is_alive(_g1h);
3443 
3444     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3445     pss->set_ref_discoverer(NULL);
3446 
3447     // Keep alive closure.
3448     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3449 
3450     // Complete GC closure
3451     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3452 
3453     // Call the reference processing task's work routine.
3454     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3455 
3456     // Note we cannot assert that the refs array is empty here as not all
3457     // of the processing tasks (specifically phase2 - pp2_work) execute
3458     // the complete_gc closure (which ordinarily would drain the queue) so
3459     // the queue may not be empty.
3460   }
3461 };
3462 
3463 // Driver routine for parallel reference processing.
3464 // Creates an instance of the ref processing gang
3465 // task and has the worker threads execute it.
3466 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3467   assert(_workers != NULL, "Need parallel worker threads.");
3468 
3469   assert(_workers->active_workers() >= ergo_workers,
3470          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3471          ergo_workers, _workers->active_workers());
3472   TaskTerminator terminator(ergo_workers, _queues);
3473   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3474 
3475   _workers->run_task(&proc_task_proxy, ergo_workers);
3476 }
3477 
3478 // End of weak reference support closures
3479 
3480 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3481   double ref_proc_start = os::elapsedTime();
3482 
3483   ReferenceProcessor* rp = _ref_processor_stw;
3484   assert(rp->discovery_enabled(), "should have been enabled");
3485 
3486   // Closure to test whether a referent is alive.
3487   G1STWIsAliveClosure is_alive(this);
3488 
3489   // Even when parallel reference processing is enabled, the processing
3490   // of JNI refs is serial and performed serially by the current thread
3491   // rather than by a worker. The following PSS will be used for processing
3492   // JNI refs.
3493 
3494   // Use only a single queue for this PSS.
3495   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3496   pss->set_ref_discoverer(NULL);
3497   assert(pss->queue_is_empty(), "pre-condition");
3498 
3499   // Keep alive closure.
3500   G1CopyingKeepAliveClosure keep_alive(this, pss);
3501 
3502   // Serial Complete GC closure
3503   G1STWDrainQueueClosure drain_queue(this, pss);
3504 
3505   // Setup the soft refs policy...
3506   rp->setup_policy(false);
3507 
3508   ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3509 
3510   ReferenceProcessorStats stats;
3511   if (!rp->processing_is_mt()) {
3512     // Serial reference processing...
3513     stats = rp->process_discovered_references(&is_alive,
3514                                               &keep_alive,
3515                                               &drain_queue,
3516                                               NULL,
3517                                               pt);
3518   } else {
3519     uint no_of_gc_workers = workers()->active_workers();
3520 
3521     // Parallel reference processing
3522     assert(no_of_gc_workers <= rp->max_num_queues(),
3523            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3524            no_of_gc_workers,  rp->max_num_queues());
3525 
3526     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3527     stats = rp->process_discovered_references(&is_alive,
3528                                               &keep_alive,
3529                                               &drain_queue,
3530                                               &par_task_executor,
3531                                               pt);
3532   }
3533 
3534   _gc_tracer_stw->report_gc_reference_stats(stats);
3535 
3536   // We have completed copying any necessary live referent objects.
3537   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3538 
3539   make_pending_list_reachable();
3540 
3541   assert(!rp->discovery_enabled(), "Postcondition");
3542   rp->verify_no_references_recorded();
3543 
3544   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3545   phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3546 }
3547 
3548 void G1CollectedHeap::make_pending_list_reachable() {
3549   if (collector_state()->in_concurrent_start_gc()) {
3550     oop pll_head = Universe::reference_pending_list();
3551     if (pll_head != NULL) {
3552       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3553       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3554     }
3555   }
3556 }
3557 
3558 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3559   Ticks start = Ticks::now();
3560   per_thread_states->flush();
3561   phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3562 }
3563 
3564 class G1PrepareEvacuationTask : public AbstractGangTask {
3565   class G1PrepareRegionsClosure : public HeapRegionClosure {
3566     G1CollectedHeap* _g1h;
3567     G1PrepareEvacuationTask* _parent_task;
3568     size_t _worker_humongous_total;
3569     size_t _worker_humongous_candidates;
3570 
3571     bool humongous_region_is_candidate(HeapRegion* region) const {
3572       assert(region->is_starts_humongous(), "Must start a humongous object");
3573 
3574       oop obj = oop(region->bottom());
3575 
3576       // Dead objects cannot be eager reclaim candidates. Due to class
3577       // unloading it is unsafe to query their classes so we return early.
3578       if (_g1h->is_obj_dead(obj, region)) {
3579         return false;
3580       }
3581 
3582       // If we do not have a complete remembered set for the region, then we can
3583       // not be sure that we have all references to it.
3584       if (!region->rem_set()->is_complete()) {
3585         return false;
3586       }
3587       // Candidate selection must satisfy the following constraints
3588       // while concurrent marking is in progress:
3589       //
3590       // * In order to maintain SATB invariants, an object must not be
3591       // reclaimed if it was allocated before the start of marking and
3592       // has not had its references scanned.  Such an object must have
3593       // its references (including type metadata) scanned to ensure no
3594       // live objects are missed by the marking process.  Objects
3595       // allocated after the start of concurrent marking don't need to
3596       // be scanned.
3597       //
3598       // * An object must not be reclaimed if it is on the concurrent
3599       // mark stack.  Objects allocated after the start of concurrent
3600       // marking are never pushed on the mark stack.
3601       //
3602       // Nominating only objects allocated after the start of concurrent
3603       // marking is sufficient to meet both constraints.  This may miss
3604       // some objects that satisfy the constraints, but the marking data
3605       // structures don't support efficiently performing the needed
3606       // additional tests or scrubbing of the mark stack.
3607       //
3608       // However, we presently only nominate is_typeArray() objects.
3609       // A humongous object containing references induces remembered
3610       // set entries on other regions.  In order to reclaim such an
3611       // object, those remembered sets would need to be cleaned up.
3612       //
3613       // We also treat is_typeArray() objects specially, allowing them
3614       // to be reclaimed even if allocated before the start of
3615       // concurrent mark.  For this we rely on mark stack insertion to
3616       // exclude is_typeArray() objects, preventing reclaiming an object
3617       // that is in the mark stack.  We also rely on the metadata for
3618       // such objects to be built-in and so ensured to be kept live.
3619       // Frequent allocation and drop of large binary blobs is an
3620       // important use case for eager reclaim, and this special handling
3621       // may reduce needed headroom.
3622 
3623       return obj->is_typeArray() &&
3624              _g1h->is_potential_eager_reclaim_candidate(region);
3625     }
3626 
3627   public:
3628     G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3629       _g1h(g1h),
3630       _parent_task(parent_task),
3631       _worker_humongous_total(0),
3632       _worker_humongous_candidates(0) { }
3633 
3634     ~G1PrepareRegionsClosure() {
3635       _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3636       _parent_task->add_humongous_total(_worker_humongous_total);
3637     }
3638 
3639     virtual bool do_heap_region(HeapRegion* hr) {
3640       // First prepare the region for scanning
3641       _g1h->rem_set()->prepare_region_for_scan(hr);
3642 
3643       // Now check if region is a humongous candidate
3644       if (!hr->is_starts_humongous()) {
3645         _g1h->register_region_with_region_attr(hr);
3646         return false;
3647       }
3648 
3649       uint index = hr->hrm_index();
3650       if (humongous_region_is_candidate(hr)) {
3651         _g1h->set_humongous_reclaim_candidate(index, true);
3652         _g1h->register_humongous_region_with_region_attr(index);
3653         _worker_humongous_candidates++;
3654         // We will later handle the remembered sets of these regions.
3655       } else {
3656         _g1h->set_humongous_reclaim_candidate(index, false);
3657         _g1h->register_region_with_region_attr(hr);
3658       }
3659       _worker_humongous_total++;
3660 
3661       return false;
3662     }
3663   };
3664 
3665   G1CollectedHeap* _g1h;
3666   HeapRegionClaimer _claimer;
3667   volatile size_t _humongous_total;
3668   volatile size_t _humongous_candidates;
3669 public:
3670   G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3671     AbstractGangTask("Prepare Evacuation"),
3672     _g1h(g1h),
3673     _claimer(_g1h->workers()->active_workers()),
3674     _humongous_total(0),
3675     _humongous_candidates(0) { }
3676 
3677   ~G1PrepareEvacuationTask() {
3678     _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3679   }
3680 
3681   void work(uint worker_id) {
3682     G1PrepareRegionsClosure cl(_g1h, this);
3683     _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3684   }
3685 
3686   void add_humongous_candidates(size_t candidates) {
3687     Atomic::add(&_humongous_candidates, candidates);
3688   }
3689 
3690   void add_humongous_total(size_t total) {
3691     Atomic::add(&_humongous_total, total);
3692   }
3693 
3694   size_t humongous_candidates() {
3695     return _humongous_candidates;
3696   }
3697 
3698   size_t humongous_total() {
3699     return _humongous_total;
3700   }
3701 };
3702 
3703 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3704   _bytes_used_during_gc = 0;
3705 
3706   _expand_heap_after_alloc_failure = true;
3707   _evacuation_failed = false;
3708 
3709   // Disable the hot card cache.
3710   _hot_card_cache->reset_hot_cache_claimed_index();
3711   _hot_card_cache->set_use_cache(false);
3712 
3713   // Initialize the GC alloc regions.
3714   _allocator->init_gc_alloc_regions(evacuation_info);
3715 
3716   {
3717     Ticks start = Ticks::now();
3718     rem_set()->prepare_for_scan_heap_roots();
3719     phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3720   }
3721 
3722   {
3723     G1PrepareEvacuationTask g1_prep_task(this);
3724     Tickspan task_time = run_task_timed(&g1_prep_task);
3725 
3726     phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3727                                            g1_prep_task.humongous_total(),
3728                                            g1_prep_task.humongous_candidates());
3729   }
3730 
3731   assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3732   _preserved_marks_set.assert_empty();
3733 
3734 #if COMPILER2_OR_JVMCI
3735   DerivedPointerTable::clear();
3736 #endif
3737 
3738   // Concurrent start needs claim bits to keep track of the marked-through CLDs.
3739   if (collector_state()->in_concurrent_start_gc()) {
3740     concurrent_mark()->pre_concurrent_start();
3741 
3742     double start_clear_claimed_marks = os::elapsedTime();
3743 
3744     ClassLoaderDataGraph::clear_claimed_marks();
3745 
3746     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3747     phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3748   }
3749 
3750   // Should G1EvacuationFailureALot be in effect for this GC?
3751   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3752 }
3753 
3754 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3755 protected:
3756   G1CollectedHeap* _g1h;
3757   G1ParScanThreadStateSet* _per_thread_states;
3758   G1ScannerTasksQueueSet* _task_queues;
3759   TaskTerminator _terminator;
3760   uint _num_workers;
3761 
3762   void evacuate_live_objects(G1ParScanThreadState* pss,
3763                              uint worker_id,
3764                              G1GCPhaseTimes::GCParPhases objcopy_phase,
3765                              G1GCPhaseTimes::GCParPhases termination_phase) {
3766     G1GCPhaseTimes* p = _g1h->phase_times();
3767 
3768     Ticks start = Ticks::now();
3769     G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3770     cl.do_void();
3771 
3772     assert(pss->queue_is_empty(), "should be empty");
3773 
3774     Tickspan evac_time = (Ticks::now() - start);
3775     p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3776 
3777     if (termination_phase == G1GCPhaseTimes::Termination) {
3778       p->record_time_secs(termination_phase, worker_id, cl.term_time());
3779       p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3780     } else {
3781       p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3782       p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3783     }
3784     assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3785   }
3786 
3787   virtual void start_work(uint worker_id) { }
3788 
3789   virtual void end_work(uint worker_id) { }
3790 
3791   virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3792 
3793   virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3794 
3795 public:
3796   G1EvacuateRegionsBaseTask(const char* name,
3797                             G1ParScanThreadStateSet* per_thread_states,
3798                             G1ScannerTasksQueueSet* task_queues,
3799                             uint num_workers) :
3800     AbstractGangTask(name),
3801     _g1h(G1CollectedHeap::heap()),
3802     _per_thread_states(per_thread_states),
3803     _task_queues(task_queues),
3804     _terminator(num_workers, _task_queues),
3805     _num_workers(num_workers)
3806   { }
3807 
3808   void work(uint worker_id) {
3809     start_work(worker_id);
3810 
3811     {
3812       ResourceMark rm;
3813 
3814       G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3815       pss->set_ref_discoverer(_g1h->ref_processor_stw());
3816 
3817       scan_roots(pss, worker_id);
3818       evacuate_live_objects(pss, worker_id);
3819     }
3820 
3821     end_work(worker_id);
3822   }
3823 };
3824 
3825 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3826   G1RootProcessor* _root_processor;
3827 
3828   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3829     _root_processor->evacuate_roots(pss, worker_id);
3830     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3831     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3832   }
3833 
3834   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3835     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3836   }
3837 
3838   void start_work(uint worker_id) {
3839     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3840   }
3841 
3842   void end_work(uint worker_id) {
3843     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3844   }
3845 
3846 public:
3847   G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3848                         G1ParScanThreadStateSet* per_thread_states,
3849                         G1ScannerTasksQueueSet* task_queues,
3850                         G1RootProcessor* root_processor,
3851                         uint num_workers) :
3852     G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3853     _root_processor(root_processor)
3854   { }
3855 };
3856 
3857 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3858   G1GCPhaseTimes* p = phase_times();
3859 
3860   {
3861     Ticks start = Ticks::now();
3862     rem_set()->merge_heap_roots(true /* initial_evacuation */);
3863     p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3864   }
3865 
3866   Tickspan task_time;
3867   const uint num_workers = workers()->active_workers();
3868 
3869   Ticks start_processing = Ticks::now();
3870   {
3871     G1RootProcessor root_processor(this, num_workers);
3872     G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3873     task_time = run_task_timed(&g1_par_task);
3874     // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3875     // To extract its code root fixup time we measure total time of this scope and
3876     // subtract from the time the WorkGang task took.
3877   }
3878   Tickspan total_processing = Ticks::now() - start_processing;
3879 
3880   p->record_initial_evac_time(task_time.seconds() * 1000.0);
3881   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3882 }
3883 
3884 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3885 
3886   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3887     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3888     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3889   }
3890 
3891   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3892     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3893   }
3894 
3895 public:
3896   G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3897                                 G1ScannerTasksQueueSet* queues,
3898                                 uint num_workers) :
3899     G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3900   }
3901 };
3902 
3903 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3904   class G1MarkScope : public MarkScope { };
3905 
3906   Tickspan task_time;
3907 
3908   Ticks start_processing = Ticks::now();
3909   {
3910     G1MarkScope code_mark_scope;
3911     G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3912     task_time = run_task_timed(&task);
3913     // See comment in evacuate_collection_set() for the reason of the scope.
3914   }
3915   Tickspan total_processing = Ticks::now() - start_processing;
3916 
3917   G1GCPhaseTimes* p = phase_times();
3918   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3919 }
3920 
3921 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3922   const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3923 
3924   while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3925 
3926     double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3927     double time_left_ms = MaxGCPauseMillis - time_used_ms;
3928 
3929     if (time_left_ms < 0 ||
3930         !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3931       log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3932                                 _collection_set.optional_region_length(), time_left_ms);
3933       break;
3934     }
3935 
3936     {
3937       Ticks start = Ticks::now();
3938       rem_set()->merge_heap_roots(false /* initial_evacuation */);
3939       phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3940     }
3941 
3942     {
3943       Ticks start = Ticks::now();
3944       evacuate_next_optional_regions(per_thread_states);
3945       phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3946     }
3947   }
3948 
3949   _collection_set.abandon_optional_collection_set(per_thread_states);
3950 }
3951 
3952 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3953                                                    G1RedirtyCardsQueueSet* rdcqs,
3954                                                    G1ParScanThreadStateSet* per_thread_states) {
3955   G1GCPhaseTimes* p = phase_times();
3956 
3957   rem_set()->cleanup_after_scan_heap_roots();
3958 
3959   // Process any discovered reference objects - we have
3960   // to do this _before_ we retire the GC alloc regions
3961   // as we may have to copy some 'reachable' referent
3962   // objects (and their reachable sub-graphs) that were
3963   // not copied during the pause.
3964   process_discovered_references(per_thread_states);
3965 
3966   G1STWIsAliveClosure is_alive(this);
3967   G1KeepAliveClosure keep_alive(this);
3968 
3969   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
3970 
3971   if (G1StringDedup::is_enabled()) {
3972     double string_dedup_time_ms = os::elapsedTime();
3973 
3974     string_dedup_cleaning(&is_alive, &keep_alive, p);
3975 
3976     double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3977     p->record_string_deduplication_time(string_cleanup_time_ms);
3978   }
3979 
3980   _allocator->release_gc_alloc_regions(evacuation_info);
3981 
3982   if (evacuation_failed()) {
3983     restore_after_evac_failure(rdcqs);
3984 
3985     // Reset the G1EvacuationFailureALot counters and flags
3986     NOT_PRODUCT(reset_evacuation_should_fail();)
3987 
3988     double recalculate_used_start = os::elapsedTime();
3989     set_used(recalculate_used());
3990     p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3991 
3992     if (_archive_allocator != NULL) {
3993       _archive_allocator->clear_used();
3994     }
3995     for (uint i = 0; i < ParallelGCThreads; i++) {
3996       if (_evacuation_failed_info_array[i].has_failed()) {
3997         _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3998       }
3999     }
4000   } else {
4001     // The "used" of the the collection set have already been subtracted
4002     // when they were freed.  Add in the bytes used.
4003     increase_used(_bytes_used_during_gc);
4004   }
4005 
4006   _preserved_marks_set.assert_empty();
4007 
4008   merge_per_thread_state_info(per_thread_states);
4009 
4010   // Reset and re-enable the hot card cache.
4011   // Note the counts for the cards in the regions in the
4012   // collection set are reset when the collection set is freed.
4013   _hot_card_cache->reset_hot_cache();
4014   _hot_card_cache->set_use_cache(true);
4015 
4016   purge_code_root_memory();
4017 
4018   redirty_logged_cards(rdcqs);
4019 
4020   free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4021 
4022   eagerly_reclaim_humongous_regions();
4023 
4024   record_obj_copy_mem_stats();
4025 
4026   evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4027   evacuation_info.set_bytes_used(_bytes_used_during_gc);
4028 
4029 #if COMPILER2_OR_JVMCI
4030   double start = os::elapsedTime();
4031   DerivedPointerTable::update_pointers();
4032   phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4033 #endif
4034   policy()->print_age_table();
4035 }
4036 
4037 void G1CollectedHeap::record_obj_copy_mem_stats() {
4038   policy()->old_gen_alloc_tracker()->
4039     add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4040 
4041   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4042                                                create_g1_evac_summary(&_old_evac_stats));
4043 }
4044 
4045 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4046   assert(!hr->is_free(), "the region should not be free");
4047   assert(!hr->is_empty(), "the region should not be empty");
4048   assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4049 
4050   if (G1VerifyBitmaps) {
4051     MemRegion mr(hr->bottom(), hr->end());
4052     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4053   }
4054 
4055   // Clear the card counts for this region.
4056   // Note: we only need to do this if the region is not young
4057   // (since we don't refine cards in young regions).
4058   if (!hr->is_young()) {
4059     _hot_card_cache->reset_card_counts(hr);
4060   }
4061 
4062   // Reset region metadata to allow reuse.
4063   hr->hr_clear(true /* clear_space */);
4064   _policy->remset_tracker()->update_at_free(hr);
4065 
4066   if (free_list != NULL) {
4067     free_list->add_ordered(hr);
4068   }
4069 }
4070 
4071 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4072                                             FreeRegionList* free_list) {
4073   assert(hr->is_humongous(), "this is only for humongous regions");
4074   assert(free_list != NULL, "pre-condition");
4075   hr->clear_humongous();
4076   free_region(hr, free_list);
4077 }
4078 
4079 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4080                                            const uint humongous_regions_removed) {
4081   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4082     MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4083     _old_set.bulk_remove(old_regions_removed);
4084     _humongous_set.bulk_remove(humongous_regions_removed);
4085   }
4086 
4087 }
4088 
4089 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4090   assert(list != NULL, "list can't be null");
4091   if (!list->is_empty()) {
4092     MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4093     _hrm->insert_list_into_free_list(list);
4094   }
4095 }
4096 
4097 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4098   decrease_used(bytes);
4099 }
4100 
4101 class G1FreeCollectionSetTask : public AbstractGangTask {
4102   // Helper class to keep statistics for the collection set freeing
4103   class FreeCSetStats {
4104     size_t _before_used_bytes;   // Usage in regions successfully evacutate
4105     size_t _after_used_bytes;    // Usage in regions failing evacuation
4106     size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4107     size_t _failure_used_words;  // Live size in failed regions
4108     size_t _failure_waste_words; // Wasted size in failed regions
4109     size_t _rs_length;           // Remembered set size
4110     uint _regions_freed;         // Number of regions freed
4111   public:
4112     FreeCSetStats() :
4113         _before_used_bytes(0),
4114         _after_used_bytes(0),
4115         _bytes_allocated_in_old_since_last_gc(0),
4116         _failure_used_words(0),
4117         _failure_waste_words(0),
4118         _rs_length(0),
4119         _regions_freed(0) { }
4120 
4121     void merge_stats(FreeCSetStats* other) {
4122       assert(other != NULL, "invariant");
4123       _before_used_bytes += other->_before_used_bytes;
4124       _after_used_bytes += other->_after_used_bytes;
4125       _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4126       _failure_used_words += other->_failure_used_words;
4127       _failure_waste_words += other->_failure_waste_words;
4128       _rs_length += other->_rs_length;
4129       _regions_freed += other->_regions_freed;
4130     }
4131 
4132     void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4133       evacuation_info->set_regions_freed(_regions_freed);
4134       evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4135 
4136       g1h->decrement_summary_bytes(_before_used_bytes);
4137       g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4138 
4139       G1Policy *policy = g1h->policy();
4140       policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4141       policy->record_rs_length(_rs_length);
4142       policy->cset_regions_freed();
4143     }
4144 
4145     void account_failed_region(HeapRegion* r) {
4146       size_t used_words = r->marked_bytes() / HeapWordSize;
4147       _failure_used_words += used_words;
4148       _failure_waste_words += HeapRegion::GrainWords - used_words;
4149       _after_used_bytes += r->used();
4150 
4151       // When moving a young gen region to old gen, we "allocate" that whole
4152       // region there. This is in addition to any already evacuated objects.
4153       // Notify the policy about that. Old gen regions do not cause an
4154       // additional allocation: both the objects still in the region and the
4155       // ones already moved are accounted for elsewhere.
4156       if (r->is_young()) {
4157         _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4158       }
4159     }
4160 
4161     void account_evacuated_region(HeapRegion* r) {
4162       _before_used_bytes += r->used();
4163       _regions_freed += 1;
4164     }
4165 
4166     void account_rs_length(HeapRegion* r) {
4167       _rs_length += r->rem_set()->occupied();
4168     }
4169   };
4170 
4171   // Closure applied to all regions in the collection set.
4172   class FreeCSetClosure : public HeapRegionClosure {
4173     // Helper to send JFR events for regions.
4174     class JFREventForRegion {
4175       EventGCPhaseParallel _event;
4176     public:
4177       JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4178         _event.set_gcId(GCId::current());
4179         _event.set_gcWorkerId(worker_id);
4180         if (region->is_young()) {
4181           _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4182         } else {
4183           _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4184         }
4185       }
4186 
4187       ~JFREventForRegion() {
4188         _event.commit();
4189       }
4190     };
4191 
4192     // Helper to do timing for region work.
4193     class TimerForRegion {
4194       Tickspan& _time;
4195       Ticks     _start_time;
4196     public:
4197       TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4198       ~TimerForRegion() {
4199         _time += Ticks::now() - _start_time;
4200       }
4201     };
4202 
4203     // FreeCSetClosure members
4204     G1CollectedHeap* _g1h;
4205     const size_t*    _surviving_young_words;
4206     uint             _worker_id;
4207     Tickspan         _young_time;
4208     Tickspan         _non_young_time;
4209     FreeCSetStats*   _stats;
4210 
4211     void assert_in_cset(HeapRegion* r) {
4212       assert(r->young_index_in_cset() != 0 &&
4213              (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4214              "Young index %u is wrong for region %u of type %s with %u young regions",
4215              r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4216     }
4217 
4218     void handle_evacuated_region(HeapRegion* r) {
4219       assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4220       stats()->account_evacuated_region(r);
4221 
4222       // Free the region and and its remembered set.
4223       _g1h->free_region(r, NULL);
4224     }
4225 
4226     void handle_failed_region(HeapRegion* r) {
4227       // Do some allocation statistics accounting. Regions that failed evacuation
4228       // are always made old, so there is no need to update anything in the young
4229       // gen statistics, but we need to update old gen statistics.
4230       stats()->account_failed_region(r);
4231 
4232       // Update the region state due to the failed evacuation.
4233       r->handle_evacuation_failure();
4234 
4235       // Add region to old set, need to hold lock.
4236       MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4237       _g1h->old_set_add(r);
4238     }
4239 
4240     Tickspan& timer_for_region(HeapRegion* r) {
4241       return r->is_young() ? _young_time : _non_young_time;
4242     }
4243 
4244     FreeCSetStats* stats() {
4245       return _stats;
4246     }
4247   public:
4248     FreeCSetClosure(const size_t* surviving_young_words,
4249                     uint worker_id,
4250                     FreeCSetStats* stats) :
4251         HeapRegionClosure(),
4252         _g1h(G1CollectedHeap::heap()),
4253         _surviving_young_words(surviving_young_words),
4254         _worker_id(worker_id),
4255         _young_time(),
4256         _non_young_time(),
4257         _stats(stats) { }
4258 
4259     virtual bool do_heap_region(HeapRegion* r) {
4260       assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4261       JFREventForRegion event(r, _worker_id);
4262       TimerForRegion timer(timer_for_region(r));
4263 
4264       _g1h->clear_region_attr(r);
4265       stats()->account_rs_length(r);
4266 
4267       if (r->is_young()) {
4268         assert_in_cset(r);
4269         r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4270       }
4271 
4272       if (r->evacuation_failed()) {
4273         handle_failed_region(r);
4274       } else {
4275         handle_evacuated_region(r);
4276       }
4277       assert(!_g1h->is_on_master_free_list(r), "sanity");
4278 
4279       return false;
4280     }
4281 
4282     void report_timing(Tickspan parallel_time) {
4283       G1GCPhaseTimes* pt = _g1h->phase_times();
4284       pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4285       if (_young_time.value() > 0) {
4286         pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4287       }
4288       if (_non_young_time.value() > 0) {
4289         pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4290       }
4291     }
4292   };
4293 
4294   // G1FreeCollectionSetTask members
4295   G1CollectedHeap*  _g1h;
4296   G1EvacuationInfo* _evacuation_info;
4297   FreeCSetStats*    _worker_stats;
4298   HeapRegionClaimer _claimer;
4299   const size_t*     _surviving_young_words;
4300   uint              _active_workers;
4301 
4302   FreeCSetStats* worker_stats(uint worker) {
4303     return &_worker_stats[worker];
4304   }
4305 
4306   void report_statistics() {
4307     // Merge the accounting
4308     FreeCSetStats total_stats;
4309     for (uint worker = 0; worker < _active_workers; worker++) {
4310       total_stats.merge_stats(worker_stats(worker));
4311     }
4312     total_stats.report(_g1h, _evacuation_info);
4313   }
4314 
4315 public:
4316   G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4317       AbstractGangTask("G1 Free Collection Set"),
4318       _g1h(G1CollectedHeap::heap()),
4319       _evacuation_info(evacuation_info),
4320       _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4321       _claimer(active_workers),
4322       _surviving_young_words(surviving_young_words),
4323       _active_workers(active_workers) {
4324     for (uint worker = 0; worker < active_workers; worker++) {
4325       ::new (&_worker_stats[worker]) FreeCSetStats();
4326     }
4327   }
4328 
4329   ~G1FreeCollectionSetTask() {
4330     Ticks serial_time = Ticks::now();
4331     report_statistics();
4332     for (uint worker = 0; worker < _active_workers; worker++) {
4333       _worker_stats[worker].~FreeCSetStats();
4334     }
4335     FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4336     _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4337   }
4338 
4339   virtual void work(uint worker_id) {
4340     EventGCPhaseParallel event;
4341     Ticks start = Ticks::now();
4342     FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4343     _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4344 
4345     // Report the total parallel time along with some more detailed metrics.
4346     cl.report_timing(Ticks::now() - start);
4347     event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4348   }
4349 };
4350 
4351 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4352   _eden.clear();
4353 
4354   // The free collections set is split up in two tasks, the first
4355   // frees the collection set and records what regions are free,
4356   // and the second one rebuilds the free list. This proved to be
4357   // more efficient than adding a sorted list to another.
4358 
4359   Ticks free_cset_start_time = Ticks::now();
4360   {
4361     uint const num_cs_regions = _collection_set.region_length();
4362     uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4363     G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4364 
4365     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4366                         cl.name(), num_workers, num_cs_regions, num_regions());
4367     workers()->run_task(&cl, num_workers);
4368   }
4369 
4370   Ticks free_cset_end_time = Ticks::now();
4371   phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4372 
4373   // Now rebuild the free region list.
4374   hrm()->rebuild_free_list(workers());
4375   phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4376 
4377   collection_set->clear();
4378 }
4379 
4380 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4381  private:
4382   FreeRegionList* _free_region_list;
4383   HeapRegionSet* _proxy_set;
4384   uint _humongous_objects_reclaimed;
4385   uint _humongous_regions_reclaimed;
4386   size_t _freed_bytes;
4387  public:
4388 
4389   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4390     _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4391   }
4392 
4393   virtual bool do_heap_region(HeapRegion* r) {
4394     if (!r->is_starts_humongous()) {
4395       return false;
4396     }
4397 
4398     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4399 
4400     oop obj = (oop)r->bottom();
4401     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4402 
4403     // The following checks whether the humongous object is live are sufficient.
4404     // The main additional check (in addition to having a reference from the roots
4405     // or the young gen) is whether the humongous object has a remembered set entry.
4406     //
4407     // A humongous object cannot be live if there is no remembered set for it
4408     // because:
4409     // - there can be no references from within humongous starts regions referencing
4410     // the object because we never allocate other objects into them.
4411     // (I.e. there are no intra-region references that may be missed by the
4412     // remembered set)
4413     // - as soon there is a remembered set entry to the humongous starts region
4414     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4415     // until the end of a concurrent mark.
4416     //
4417     // It is not required to check whether the object has been found dead by marking
4418     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4419     // all objects allocated during that time are considered live.
4420     // SATB marking is even more conservative than the remembered set.
4421     // So if at this point in the collection there is no remembered set entry,
4422     // nobody has a reference to it.
4423     // At the start of collection we flush all refinement logs, and remembered sets
4424     // are completely up-to-date wrt to references to the humongous object.
4425     //
4426     // Other implementation considerations:
4427     // - never consider object arrays at this time because they would pose
4428     // considerable effort for cleaning up the the remembered sets. This is
4429     // required because stale remembered sets might reference locations that
4430     // are currently allocated into.
4431     uint region_idx = r->hrm_index();
4432     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4433         !r->rem_set()->is_empty()) {
4434       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",
4435                                region_idx,
4436                                (size_t)obj->size() * HeapWordSize,
4437                                p2i(r->bottom()),
4438                                r->rem_set()->occupied(),
4439                                r->rem_set()->strong_code_roots_list_length(),
4440                                next_bitmap->is_marked(r->bottom()),
4441                                g1h->is_humongous_reclaim_candidate(region_idx),
4442                                obj->is_typeArray()
4443                               );
4444       return false;
4445     }
4446 
4447     guarantee(obj->is_typeArray(),
4448               "Only eagerly reclaiming type arrays is supported, but the object "
4449               PTR_FORMAT " is not.", p2i(r->bottom()));
4450 
4451     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",
4452                              region_idx,
4453                              (size_t)obj->size() * HeapWordSize,
4454                              p2i(r->bottom()),
4455                              r->rem_set()->occupied(),
4456                              r->rem_set()->strong_code_roots_list_length(),
4457                              next_bitmap->is_marked(r->bottom()),
4458                              g1h->is_humongous_reclaim_candidate(region_idx),
4459                              obj->is_typeArray()
4460                             );
4461 
4462     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4463     cm->humongous_object_eagerly_reclaimed(r);
4464     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4465            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4466            region_idx,
4467            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4468            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4469     _humongous_objects_reclaimed++;
4470     do {
4471       HeapRegion* next = g1h->next_region_in_humongous(r);
4472       _freed_bytes += r->used();
4473       r->set_containing_set(NULL);
4474       _humongous_regions_reclaimed++;
4475       g1h->free_humongous_region(r, _free_region_list);
4476       r = next;
4477     } while (r != NULL);
4478 
4479     return false;
4480   }
4481 
4482   uint humongous_objects_reclaimed() {
4483     return _humongous_objects_reclaimed;
4484   }
4485 
4486   uint humongous_regions_reclaimed() {
4487     return _humongous_regions_reclaimed;
4488   }
4489 
4490   size_t bytes_freed() const {
4491     return _freed_bytes;
4492   }
4493 };
4494 
4495 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4496   assert_at_safepoint_on_vm_thread();
4497 
4498   if (!G1EagerReclaimHumongousObjects ||
4499       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4500     phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4501     return;
4502   }
4503 
4504   double start_time = os::elapsedTime();
4505 
4506   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4507 
4508   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4509   heap_region_iterate(&cl);
4510 
4511   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4512 
4513   G1HRPrinter* hrp = hr_printer();
4514   if (hrp->is_active()) {
4515     FreeRegionListIterator iter(&local_cleanup_list);
4516     while (iter.more_available()) {
4517       HeapRegion* hr = iter.get_next();
4518       hrp->cleanup(hr);
4519     }
4520   }
4521 
4522   prepend_to_freelist(&local_cleanup_list);
4523   decrement_summary_bytes(cl.bytes_freed());
4524 
4525   phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4526                                                        cl.humongous_objects_reclaimed());
4527 }
4528 
4529 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4530 public:
4531   virtual bool do_heap_region(HeapRegion* r) {
4532     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4533     G1CollectedHeap::heap()->clear_region_attr(r);
4534     r->clear_young_index_in_cset();
4535     return false;
4536   }
4537 };
4538 
4539 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4540   G1AbandonCollectionSetClosure cl;
4541   collection_set_iterate_all(&cl);
4542 
4543   collection_set->clear();
4544   collection_set->stop_incremental_building();
4545 }
4546 
4547 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4548   return _allocator->is_retained_old_region(hr);
4549 }
4550 
4551 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4552   _eden.add(hr);
4553   _policy->set_region_eden(hr);
4554 }
4555 
4556 #ifdef ASSERT
4557 
4558 class NoYoungRegionsClosure: public HeapRegionClosure {
4559 private:
4560   bool _success;
4561 public:
4562   NoYoungRegionsClosure() : _success(true) { }
4563   bool do_heap_region(HeapRegion* r) {
4564     if (r->is_young()) {
4565       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4566                             p2i(r->bottom()), p2i(r->end()));
4567       _success = false;
4568     }
4569     return false;
4570   }
4571   bool success() { return _success; }
4572 };
4573 
4574 bool G1CollectedHeap::check_young_list_empty() {
4575   bool ret = (young_regions_count() == 0);
4576 
4577   NoYoungRegionsClosure closure;
4578   heap_region_iterate(&closure);
4579   ret = ret && closure.success();
4580 
4581   return ret;
4582 }
4583 
4584 #endif // ASSERT
4585 
4586 class TearDownRegionSetsClosure : public HeapRegionClosure {
4587   HeapRegionSet *_old_set;
4588 
4589 public:
4590   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4591 
4592   bool do_heap_region(HeapRegion* r) {
4593     if (r->is_old()) {
4594       _old_set->remove(r);
4595     } else if(r->is_young()) {
4596       r->uninstall_surv_rate_group();
4597     } else {
4598       // We ignore free regions, we'll empty the free list afterwards.
4599       // We ignore humongous and archive regions, we're not tearing down these
4600       // sets.
4601       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4602              "it cannot be another type");
4603     }
4604     return false;
4605   }
4606 
4607   ~TearDownRegionSetsClosure() {
4608     assert(_old_set->is_empty(), "post-condition");
4609   }
4610 };
4611 
4612 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4613   assert_at_safepoint_on_vm_thread();
4614 
4615   if (!free_list_only) {
4616     TearDownRegionSetsClosure cl(&_old_set);
4617     heap_region_iterate(&cl);
4618 
4619     // Note that emptying the _young_list is postponed and instead done as
4620     // the first step when rebuilding the regions sets again. The reason for
4621     // this is that during a full GC string deduplication needs to know if
4622     // a collected region was young or old when the full GC was initiated.
4623   }
4624   _hrm->remove_all_free_regions();
4625 }
4626 
4627 void G1CollectedHeap::increase_used(size_t bytes) {
4628   _summary_bytes_used += bytes;
4629 }
4630 
4631 void G1CollectedHeap::decrease_used(size_t bytes) {
4632   assert(_summary_bytes_used >= bytes,
4633          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4634          _summary_bytes_used, bytes);
4635   _summary_bytes_used -= bytes;
4636 }
4637 
4638 void G1CollectedHeap::set_used(size_t bytes) {
4639   _summary_bytes_used = bytes;
4640 }
4641 
4642 class RebuildRegionSetsClosure : public HeapRegionClosure {
4643 private:
4644   bool _free_list_only;
4645 
4646   HeapRegionSet* _old_set;
4647   HeapRegionManager* _hrm;
4648 
4649   size_t _total_used;
4650 
4651 public:
4652   RebuildRegionSetsClosure(bool free_list_only,
4653                            HeapRegionSet* old_set,
4654                            HeapRegionManager* hrm) :
4655     _free_list_only(free_list_only),
4656     _old_set(old_set), _hrm(hrm), _total_used(0) {
4657     assert(_hrm->num_free_regions() == 0, "pre-condition");
4658     if (!free_list_only) {
4659       assert(_old_set->is_empty(), "pre-condition");
4660     }
4661   }
4662 
4663   bool do_heap_region(HeapRegion* r) {
4664     if (r->is_empty()) {
4665       assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4666       // Add free regions to the free list
4667       r->set_free();
4668       _hrm->insert_into_free_list(r);
4669     } else if (!_free_list_only) {
4670       assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4671 
4672       if (r->is_archive() || r->is_humongous()) {
4673         // We ignore archive and humongous regions. We left these sets unchanged.
4674       } else {
4675         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4676         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4677         r->move_to_old();
4678         _old_set->add(r);
4679       }
4680       _total_used += r->used();
4681     }
4682 
4683     return false;
4684   }
4685 
4686   size_t total_used() {
4687     return _total_used;
4688   }
4689 };
4690 
4691 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4692   assert_at_safepoint_on_vm_thread();
4693 
4694   if (!free_list_only) {
4695     _eden.clear();
4696     _survivor.clear();
4697   }
4698 
4699   RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4700   heap_region_iterate(&cl);
4701 
4702   if (!free_list_only) {
4703     set_used(cl.total_used());
4704     if (_archive_allocator != NULL) {
4705       _archive_allocator->clear_used();
4706     }
4707   }
4708   assert_used_and_recalculate_used_equal(this);
4709 }
4710 
4711 // Methods for the mutator alloc region
4712 
4713 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4714                                                       bool force,
4715                                                       uint node_index) {
4716   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4717   bool should_allocate = policy()->should_allocate_mutator_region();
4718   if (force || should_allocate) {
4719     HeapRegion* new_alloc_region = new_region(word_size,
4720                                               HeapRegionType::Eden,
4721                                               false /* do_expand */,
4722                                               node_index);
4723     if (new_alloc_region != NULL) {
4724       set_region_short_lived_locked(new_alloc_region);
4725       _hr_printer.alloc(new_alloc_region, !should_allocate);
4726       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4727       _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4728       return new_alloc_region;
4729     }
4730   }
4731   return NULL;
4732 }
4733 
4734 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4735                                                   size_t allocated_bytes) {
4736   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4737   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4738 
4739   collection_set()->add_eden_region(alloc_region);
4740   increase_used(allocated_bytes);
4741   _eden.add_used_bytes(allocated_bytes);
4742   _hr_printer.retire(alloc_region);
4743 
4744   // We update the eden sizes here, when the region is retired,
4745   // instead of when it's allocated, since this is the point that its
4746   // used space has been recorded in _summary_bytes_used.
4747   g1mm()->update_eden_size();
4748 }
4749 
4750 // Methods for the GC alloc regions
4751 
4752 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4753   if (dest.is_old()) {
4754     return true;
4755   } else {
4756     return survivor_regions_count() < policy()->max_survivor_regions();
4757   }
4758 }
4759 
4760 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4761   assert(FreeList_lock->owned_by_self(), "pre-condition");
4762 
4763   if (!has_more_regions(dest)) {
4764     return NULL;
4765   }
4766 
4767   HeapRegionType type;
4768   if (dest.is_young()) {
4769     type = HeapRegionType::Survivor;
4770   } else {
4771     type = HeapRegionType::Old;
4772   }
4773 
4774   HeapRegion* new_alloc_region = new_region(word_size,
4775                                             type,
4776                                             true /* do_expand */,
4777                                             node_index);
4778 
4779   if (new_alloc_region != NULL) {
4780     if (type.is_survivor()) {
4781       new_alloc_region->set_survivor();
4782       _survivor.add(new_alloc_region);
4783       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4784     } else {
4785       new_alloc_region->set_old();
4786       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4787     }
4788     _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4789     register_region_with_region_attr(new_alloc_region);
4790     _hr_printer.alloc(new_alloc_region);
4791     return new_alloc_region;
4792   }
4793   return NULL;
4794 }
4795 
4796 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4797                                              size_t allocated_bytes,
4798                                              G1HeapRegionAttr dest) {
4799   _bytes_used_during_gc += allocated_bytes;
4800   if (dest.is_old()) {
4801     old_set_add(alloc_region);
4802   } else {
4803     assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4804     _survivor.add_used_bytes(allocated_bytes);
4805   }
4806 
4807   bool const during_im = collector_state()->in_concurrent_start_gc();
4808   if (during_im && allocated_bytes > 0) {
4809     _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4810   }
4811   _hr_printer.retire(alloc_region);
4812 }
4813 
4814 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4815   bool expanded = false;
4816   uint index = _hrm->find_highest_free(&expanded);
4817 
4818   if (index != G1_NO_HRM_INDEX) {
4819     if (expanded) {
4820       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4821                                 HeapRegion::GrainWords * HeapWordSize);
4822     }
4823     return _hrm->allocate_free_regions_starting_at(index, 1);
4824   }
4825   return NULL;
4826 }
4827 
4828 // Optimized nmethod scanning
4829 
4830 class RegisterNMethodOopClosure: public OopClosure {
4831   G1CollectedHeap* _g1h;
4832   nmethod* _nm;
4833 
4834   template <class T> void do_oop_work(T* p) {
4835     T heap_oop = RawAccess<>::oop_load(p);
4836     if (!CompressedOops::is_null(heap_oop)) {
4837       oop obj = CompressedOops::decode_not_null(heap_oop);
4838       HeapRegion* hr = _g1h->heap_region_containing(obj);
4839       assert(!hr->is_continues_humongous(),
4840              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4841              " starting at " HR_FORMAT,
4842              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4843 
4844       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4845       hr->add_strong_code_root_locked(_nm);
4846     }
4847   }
4848 
4849 public:
4850   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4851     _g1h(g1h), _nm(nm) {}
4852 
4853   void do_oop(oop* p)       { do_oop_work(p); }
4854   void do_oop(narrowOop* p) { do_oop_work(p); }
4855 };
4856 
4857 class UnregisterNMethodOopClosure: public OopClosure {
4858   G1CollectedHeap* _g1h;
4859   nmethod* _nm;
4860 
4861   template <class T> void do_oop_work(T* p) {
4862     T heap_oop = RawAccess<>::oop_load(p);
4863     if (!CompressedOops::is_null(heap_oop)) {
4864       oop obj = CompressedOops::decode_not_null(heap_oop);
4865       HeapRegion* hr = _g1h->heap_region_containing(obj);
4866       assert(!hr->is_continues_humongous(),
4867              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4868              " starting at " HR_FORMAT,
4869              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4870 
4871       hr->remove_strong_code_root(_nm);
4872     }
4873   }
4874 
4875 public:
4876   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4877     _g1h(g1h), _nm(nm) {}
4878 
4879   void do_oop(oop* p)       { do_oop_work(p); }
4880   void do_oop(narrowOop* p) { do_oop_work(p); }
4881 };
4882 
4883 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4884   guarantee(nm != NULL, "sanity");
4885   RegisterNMethodOopClosure reg_cl(this, nm);
4886   nm->oops_do(&reg_cl);
4887 }
4888 
4889 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4890   guarantee(nm != NULL, "sanity");
4891   UnregisterNMethodOopClosure reg_cl(this, nm);
4892   nm->oops_do(&reg_cl, true);
4893 }
4894 
4895 void G1CollectedHeap::purge_code_root_memory() {
4896   double purge_start = os::elapsedTime();
4897   G1CodeRootSet::purge();
4898   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4899   phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4900 }
4901 
4902 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4903   G1CollectedHeap* _g1h;
4904 
4905 public:
4906   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4907     _g1h(g1h) {}
4908 
4909   void do_code_blob(CodeBlob* cb) {
4910     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4911     if (nm == NULL) {
4912       return;
4913     }
4914 
4915     _g1h->register_nmethod(nm);
4916   }
4917 };
4918 
4919 void G1CollectedHeap::rebuild_strong_code_roots() {
4920   RebuildStrongCodeRootClosure blob_cl(this);
4921   CodeCache::blobs_do(&blob_cl);
4922 }
4923 
4924 void G1CollectedHeap::initialize_serviceability() {
4925   _g1mm->initialize_serviceability();
4926 }
4927 
4928 MemoryUsage G1CollectedHeap::memory_usage() {
4929   return _g1mm->memory_usage();
4930 }
4931 
4932 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4933   return _g1mm->memory_managers();
4934 }
4935 
4936 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4937   return _g1mm->memory_pools();
4938 }