1 /*
   2  * Copyright (c) 2001, 2020, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoaderDataGraph.hpp"
  27 #include "classfile/metadataOnStackMark.hpp"
  28 #include "classfile/stringTable.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "gc/g1/g1Allocator.inline.hpp"
  32 #include "gc/g1/g1Arguments.hpp"
  33 #include "gc/g1/g1BarrierSet.hpp"
  34 #include "gc/g1/g1CardTableEntryClosure.hpp"
  35 #include "gc/g1/g1CollectedHeap.inline.hpp"
  36 #include "gc/g1/g1CollectionSet.hpp"
  37 #include "gc/g1/g1CollectorState.hpp"
  38 #include "gc/g1/g1ConcurrentRefine.hpp"
  39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
  40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
  41 #include "gc/g1/g1DirtyCardQueue.hpp"
  42 #include "gc/g1/g1EvacStats.inline.hpp"
  43 #include "gc/g1/g1FullCollector.hpp"
  44 #include "gc/g1/g1GCParPhaseTimesTracker.hpp"
  45 #include "gc/g1/g1GCPhaseTimes.hpp"
  46 #include "gc/g1/g1HeapSizingPolicy.hpp"
  47 #include "gc/g1/g1HeapTransition.hpp"
  48 #include "gc/g1/g1HeapVerifier.hpp"
  49 #include "gc/g1/g1HotCardCache.hpp"
  50 #include "gc/g1/g1InitLogger.hpp"
  51 #include "gc/g1/g1MemoryPool.hpp"
  52 #include "gc/g1/g1OopClosures.inline.hpp"
  53 #include "gc/g1/g1ParallelCleaning.hpp"
  54 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  55 #include "gc/g1/g1Policy.hpp"
  56 #include "gc/g1/g1RedirtyCardsQueue.hpp"
  57 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  58 #include "gc/g1/g1RemSet.hpp"
  59 #include "gc/g1/g1RootClosures.hpp"
  60 #include "gc/g1/g1RootProcessor.hpp"
  61 #include "gc/g1/g1SATBMarkQueueSet.hpp"
  62 #include "gc/g1/g1StringDedup.hpp"
  63 #include "gc/g1/g1ThreadLocalData.hpp"
  64 #include "gc/g1/g1Trace.hpp"
  65 #include "gc/g1/g1YCTypes.hpp"
  66 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  67 #include "gc/g1/g1VMOperations.hpp"
  68 #include "gc/g1/heapRegion.inline.hpp"
  69 #include "gc/g1/heapRegionRemSet.hpp"
  70 #include "gc/g1/heapRegionSet.inline.hpp"
  71 #include "gc/shared/concurrentGCBreakpoints.hpp"
  72 #include "gc/shared/gcBehaviours.hpp"
  73 #include "gc/shared/gcHeapSummary.hpp"
  74 #include "gc/shared/gcId.hpp"
  75 #include "gc/shared/gcLocker.hpp"
  76 #include "gc/shared/gcTimer.hpp"
  77 #include "gc/shared/gcTraceTime.inline.hpp"
  78 #include "gc/shared/generationSpec.hpp"
  79 #include "gc/shared/isGCActiveMark.hpp"
  80 #include "gc/shared/locationPrinter.inline.hpp"
  81 #include "gc/shared/oopStorageParState.hpp"
  82 #include "gc/shared/preservedMarks.inline.hpp"
  83 #include "gc/shared/suspendibleThreadSet.hpp"
  84 #include "gc/shared/referenceProcessor.inline.hpp"
  85 #include "gc/shared/taskTerminator.hpp"
  86 #include "gc/shared/taskqueue.inline.hpp"
  87 #include "gc/shared/weakProcessor.inline.hpp"
  88 #include "gc/shared/workerPolicy.hpp"
  89 #include "logging/log.hpp"
  90 #include "memory/allocation.hpp"
  91 #include "memory/iterator.hpp"
  92 #include "memory/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_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         return result;
 897       }
 898 
 899       if (succeeded) {
 900         // We successfully scheduled a collection which failed to allocate. No
 901         // point in trying to allocate further. We'll just return NULL.
 902         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 903                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 904         return NULL;
 905       }
 906       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 907                            Thread::current()->name(), word_size);
 908     } else {
 909       // Failed to schedule a collection.
 910       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 911         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 912                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 913         return NULL;
 914       }
 915       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 916       // The GCLocker is either active or the GCLocker initiated
 917       // GC has not yet been performed. Stall until it is and
 918       // then retry the allocation.
 919       GCLocker::stall_until_clear();
 920       gclocker_retry_count += 1;
 921     }
 922 
 923 
 924     // We can reach here if we were unsuccessful in scheduling a
 925     // collection (because another thread beat us to it) or if we were
 926     // stalled due to the GC locker. In either can we should retry the
 927     // allocation attempt in case another thread successfully
 928     // performed a collection and reclaimed enough space.
 929     // Humongous object allocation always needs a lock, so we wait for the retry
 930     // in the next iteration of the loop, unlike for the regular iteration case.
 931     // Give a warning if we seem to be looping forever.
 932 
 933     if ((QueuedAllocationWarningCount > 0) &&
 934         (try_count % QueuedAllocationWarningCount == 0)) {
 935       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 936                              Thread::current()->name(), try_count, word_size);
 937     }
 938   }
 939 
 940   ShouldNotReachHere();
 941   return NULL;
 942 }
 943 
 944 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 945                                                            bool expect_null_mutator_alloc_region) {
 946   assert_at_safepoint_on_vm_thread();
 947   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 948          "the current alloc region was unexpectedly found to be non-NULL");
 949 
 950   if (!is_humongous(word_size)) {
 951     return _allocator->attempt_allocation_locked(word_size);
 952   } else {
 953     HeapWord* result = humongous_obj_allocate(word_size);
 954     if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
 955       collector_state()->set_initiate_conc_mark_if_possible(true);
 956     }
 957     return result;
 958   }
 959 
 960   ShouldNotReachHere();
 961 }
 962 
 963 class PostCompactionPrinterClosure: public HeapRegionClosure {
 964 private:
 965   G1HRPrinter* _hr_printer;
 966 public:
 967   bool do_heap_region(HeapRegion* hr) {
 968     assert(!hr->is_young(), "not expecting to find young regions");
 969     _hr_printer->post_compaction(hr);
 970     return false;
 971   }
 972 
 973   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 974     : _hr_printer(hr_printer) { }
 975 };
 976 
 977 void G1CollectedHeap::print_hrm_post_compaction() {
 978   if (_hr_printer.is_active()) {
 979     PostCompactionPrinterClosure cl(hr_printer());
 980     heap_region_iterate(&cl);
 981   }
 982 }
 983 
 984 void G1CollectedHeap::abort_concurrent_cycle() {
 985   // If we start the compaction before the CM threads finish
 986   // scanning the root regions we might trip them over as we'll
 987   // be moving objects / updating references. So let's wait until
 988   // they are done. By telling them to abort, they should complete
 989   // early.
 990   _cm->root_regions()->abort();
 991   _cm->root_regions()->wait_until_scan_finished();
 992 
 993   // Disable discovery and empty the discovered lists
 994   // for the CM ref processor.
 995   _ref_processor_cm->disable_discovery();
 996   _ref_processor_cm->abandon_partial_discovery();
 997   _ref_processor_cm->verify_no_references_recorded();
 998 
 999   // Abandon current iterations of concurrent marking and concurrent
1000   // refinement, if any are in progress.
1001   concurrent_mark()->concurrent_cycle_abort();
1002 }
1003 
1004 void G1CollectedHeap::prepare_heap_for_full_collection() {
1005   // Make sure we'll choose a new allocation region afterwards.
1006   _allocator->release_mutator_alloc_regions();
1007   _allocator->abandon_gc_alloc_regions();
1008 
1009   // We may have added regions to the current incremental collection
1010   // set between the last GC or pause and now. We need to clear the
1011   // incremental collection set and then start rebuilding it afresh
1012   // after this full GC.
1013   abandon_collection_set(collection_set());
1014 
1015   tear_down_region_sets(false /* free_list_only */);
1016 
1017   hrm()->prepare_for_full_collection_start();
1018 }
1019 
1020 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1021   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1022   assert_used_and_recalculate_used_equal(this);
1023   _verifier->verify_region_sets_optional();
1024   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1025   _verifier->check_bitmaps("Full GC Start");
1026 }
1027 
1028 void G1CollectedHeap::prepare_heap_for_mutators() {
1029   hrm()->prepare_for_full_collection_end();
1030 
1031   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1032   ClassLoaderDataGraph::purge();
1033   MetaspaceUtils::verify_metrics();
1034 
1035   // Prepare heap for normal collections.
1036   assert(num_free_regions() == 0, "we should not have added any free regions");
1037   rebuild_region_sets(false /* free_list_only */);
1038   abort_refinement();
1039   resize_heap_if_necessary();
1040 
1041   // Rebuild the strong code root lists for each region
1042   rebuild_strong_code_roots();
1043 
1044   // Purge code root memory
1045   purge_code_root_memory();
1046 
1047   // Start a new incremental collection set for the next pause
1048   start_new_collection_set();
1049 
1050   _allocator->init_mutator_alloc_regions();
1051 
1052   // Post collection state updates.
1053   MetaspaceGC::compute_new_size();
1054 }
1055 
1056 void G1CollectedHeap::abort_refinement() {
1057   if (_hot_card_cache->use_cache()) {
1058     _hot_card_cache->reset_hot_cache();
1059   }
1060 
1061   // Discard all remembered set updates and reset refinement statistics.
1062   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1063   assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1064          "DCQS should be empty");
1065   concurrent_refine()->get_and_reset_refinement_stats();
1066 }
1067 
1068 void G1CollectedHeap::verify_after_full_collection() {
1069   _hrm->verify_optional();
1070   _verifier->verify_region_sets_optional();
1071   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1072   // Clear the previous marking bitmap, if needed for bitmap verification.
1073   // Note we cannot do this when we clear the next marking bitmap in
1074   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1075   // objects marked during a full GC against the previous bitmap.
1076   // But we need to clear it before calling check_bitmaps below since
1077   // the full GC has compacted objects and updated TAMS but not updated
1078   // the prev bitmap.
1079   if (G1VerifyBitmaps) {
1080     GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1081     _cm->clear_prev_bitmap(workers());
1082   }
1083   // This call implicitly verifies that the next bitmap is clear after Full GC.
1084   _verifier->check_bitmaps("Full GC End");
1085 
1086   // At this point there should be no regions in the
1087   // entire heap tagged as young.
1088   assert(check_young_list_empty(), "young list should be empty at this point");
1089 
1090   // Note: since we've just done a full GC, concurrent
1091   // marking is no longer active. Therefore we need not
1092   // re-enable reference discovery for the CM ref processor.
1093   // That will be done at the start of the next marking cycle.
1094   // We also know that the STW processor should no longer
1095   // discover any new references.
1096   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1097   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1098   _ref_processor_stw->verify_no_references_recorded();
1099   _ref_processor_cm->verify_no_references_recorded();
1100 }
1101 
1102 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1103   // Post collection logging.
1104   // We should do this after we potentially resize the heap so
1105   // that all the COMMIT / UNCOMMIT events are generated before
1106   // the compaction events.
1107   print_hrm_post_compaction();
1108   heap_transition->print();
1109   print_heap_after_gc();
1110   print_heap_regions();
1111 }
1112 
1113 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1114                                          bool clear_all_soft_refs) {
1115   assert_at_safepoint_on_vm_thread();
1116 
1117   if (GCLocker::check_active_before_gc()) {
1118     // Full GC was not completed.
1119     return false;
1120   }
1121 
1122   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1123       soft_ref_policy()->should_clear_all_soft_refs();
1124 
1125   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1126   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1127 
1128   collector.prepare_collection();
1129   collector.collect();
1130   collector.complete_collection();
1131 
1132   // Full collection was successfully completed.
1133   return true;
1134 }
1135 
1136 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1137   // Currently, there is no facility in the do_full_collection(bool) API to notify
1138   // the caller that the collection did not succeed (e.g., because it was locked
1139   // out by the GC locker). So, right now, we'll ignore the return value.
1140   bool dummy = do_full_collection(true,                /* explicit_gc */
1141                                   clear_all_soft_refs);
1142 }
1143 
1144 void G1CollectedHeap::resize_heap_if_necessary() {
1145   assert_at_safepoint_on_vm_thread();
1146 
1147   bool should_expand;
1148   size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
1149 
1150   if (resize_amount == 0) {
1151     return;
1152   } else if (should_expand) {
1153     expand(resize_amount, _workers);
1154   } else {
1155     shrink(resize_amount);
1156   }
1157 }
1158 
1159 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1160                                                             bool do_gc,
1161                                                             bool clear_all_soft_refs,
1162                                                             bool expect_null_mutator_alloc_region,
1163                                                             bool* gc_succeeded) {
1164   *gc_succeeded = true;
1165   // Let's attempt the allocation first.
1166   HeapWord* result =
1167     attempt_allocation_at_safepoint(word_size,
1168                                     expect_null_mutator_alloc_region);
1169   if (result != NULL) {
1170     return result;
1171   }
1172 
1173   // In a G1 heap, we're supposed to keep allocation from failing by
1174   // incremental pauses.  Therefore, at least for now, we'll favor
1175   // expansion over collection.  (This might change in the future if we can
1176   // do something smarter than full collection to satisfy a failed alloc.)
1177   result = expand_and_allocate(word_size);
1178   if (result != NULL) {
1179     return result;
1180   }
1181 
1182   if (do_gc) {
1183     // Expansion didn't work, we'll try to do a Full GC.
1184     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1185                                        clear_all_soft_refs);
1186   }
1187 
1188   return NULL;
1189 }
1190 
1191 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1192                                                      bool* succeeded) {
1193   assert_at_safepoint_on_vm_thread();
1194 
1195   // Attempts to allocate followed by Full GC.
1196   HeapWord* result =
1197     satisfy_failed_allocation_helper(word_size,
1198                                      true,  /* do_gc */
1199                                      false, /* clear_all_soft_refs */
1200                                      false, /* expect_null_mutator_alloc_region */
1201                                      succeeded);
1202 
1203   if (result != NULL || !*succeeded) {
1204     return result;
1205   }
1206 
1207   // Attempts to allocate followed by Full GC that will collect all soft references.
1208   result = satisfy_failed_allocation_helper(word_size,
1209                                             true, /* do_gc */
1210                                             true, /* clear_all_soft_refs */
1211                                             true, /* expect_null_mutator_alloc_region */
1212                                             succeeded);
1213 
1214   if (result != NULL || !*succeeded) {
1215     return result;
1216   }
1217 
1218   // Attempts to allocate, no GC
1219   result = satisfy_failed_allocation_helper(word_size,
1220                                             false, /* do_gc */
1221                                             false, /* clear_all_soft_refs */
1222                                             true,  /* expect_null_mutator_alloc_region */
1223                                             succeeded);
1224 
1225   if (result != NULL) {
1226     return result;
1227   }
1228 
1229   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1230          "Flag should have been handled and cleared prior to this point");
1231 
1232   // What else?  We might try synchronous finalization later.  If the total
1233   // space available is large enough for the allocation, then a more
1234   // complete compaction phase than we've tried so far might be
1235   // appropriate.
1236   return NULL;
1237 }
1238 
1239 // Attempting to expand the heap sufficiently
1240 // to support an allocation of the given "word_size".  If
1241 // successful, perform the allocation and return the address of the
1242 // allocated block, or else "NULL".
1243 
1244 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1245   assert_at_safepoint_on_vm_thread();
1246 
1247   _verifier->verify_region_sets_optional();
1248 
1249   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1250   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1251                             word_size * HeapWordSize);
1252 
1253 
1254   if (expand(expand_bytes, _workers)) {
1255     _hrm->verify_optional();
1256     _verifier->verify_region_sets_optional();
1257     return attempt_allocation_at_safepoint(word_size,
1258                                            false /* expect_null_mutator_alloc_region */);
1259   }
1260   return NULL;
1261 }
1262 
1263 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1264   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1265   aligned_expand_bytes = align_up(aligned_expand_bytes,
1266                                        HeapRegion::GrainBytes);
1267 
1268   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1269                             expand_bytes, aligned_expand_bytes);
1270 
1271   if (is_maximal_no_gc()) {
1272     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1273     return false;
1274   }
1275 
1276   double expand_heap_start_time_sec = os::elapsedTime();
1277   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1278   assert(regions_to_expand > 0, "Must expand by at least one region");
1279 
1280   uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1281   if (expand_time_ms != NULL) {
1282     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1283   }
1284 
1285   if (expanded_by > 0) {
1286     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1287     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1288     policy()->record_new_heap_size(num_regions());
1289   } else {
1290     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1291 
1292     // The expansion of the virtual storage space was unsuccessful.
1293     // Let's see if it was because we ran out of swap.
1294     if (G1ExitOnExpansionFailure &&
1295         _hrm->available() >= regions_to_expand) {
1296       // We had head room...
1297       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1298     }
1299   }
1300   return regions_to_expand > 0;
1301 }
1302 
1303 bool G1CollectedHeap::expand_single_region(uint node_index) {
1304   uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1305 
1306   if (expanded_by == 0) {
1307     assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1308     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1309     return false;
1310   }
1311 
1312   policy()->record_new_heap_size(num_regions());
1313   return true;
1314 }
1315 
1316 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1317   size_t aligned_shrink_bytes =
1318     ReservedSpace::page_align_size_down(shrink_bytes);
1319   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1320                                          HeapRegion::GrainBytes);
1321   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1322 
1323   uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1324   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1325 
1326   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",
1327                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1328   if (num_regions_removed > 0) {
1329     policy()->record_new_heap_size(num_regions());
1330   } else {
1331     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1332   }
1333 }
1334 
1335 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1336   _verifier->verify_region_sets_optional();
1337 
1338   // We should only reach here at the end of a Full GC or during Remark which
1339   // means we should not not be holding to any GC alloc regions. The method
1340   // below will make sure of that and do any remaining clean up.
1341   _allocator->abandon_gc_alloc_regions();
1342 
1343   // Instead of tearing down / rebuilding the free lists here, we
1344   // could instead use the remove_all_pending() method on free_list to
1345   // remove only the ones that we need to remove.
1346   tear_down_region_sets(true /* free_list_only */);
1347   shrink_helper(shrink_bytes);
1348   rebuild_region_sets(true /* free_list_only */);
1349 
1350   _hrm->verify_optional();
1351   _verifier->verify_region_sets_optional();
1352 }
1353 
1354 class OldRegionSetChecker : public HeapRegionSetChecker {
1355 public:
1356   void check_mt_safety() {
1357     // Master Old Set MT safety protocol:
1358     // (a) If we're at a safepoint, operations on the master old set
1359     // should be invoked:
1360     // - by the VM thread (which will serialize them), or
1361     // - by the GC workers while holding the FreeList_lock, if we're
1362     //   at a safepoint for an evacuation pause (this lock is taken
1363     //   anyway when an GC alloc region is retired so that a new one
1364     //   is allocated from the free list), or
1365     // - by the GC workers while holding the OldSets_lock, if we're at a
1366     //   safepoint for a cleanup pause.
1367     // (b) If we're not at a safepoint, operations on the master old set
1368     // should be invoked while holding the Heap_lock.
1369 
1370     if (SafepointSynchronize::is_at_safepoint()) {
1371       guarantee(Thread::current()->is_VM_thread() ||
1372                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1373                 "master old set MT safety protocol at a safepoint");
1374     } else {
1375       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1376     }
1377   }
1378   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1379   const char* get_description() { return "Old Regions"; }
1380 };
1381 
1382 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1383 public:
1384   void check_mt_safety() {
1385     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1386               "May only change archive regions during initialization or safepoint.");
1387   }
1388   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1389   const char* get_description() { return "Archive Regions"; }
1390 };
1391 
1392 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1393 public:
1394   void check_mt_safety() {
1395     // Humongous Set MT safety protocol:
1396     // (a) If we're at a safepoint, operations on the master humongous
1397     // set should be invoked by either the VM thread (which will
1398     // serialize them) or by the GC workers while holding the
1399     // OldSets_lock.
1400     // (b) If we're not at a safepoint, operations on the master
1401     // humongous set should be invoked while holding the Heap_lock.
1402 
1403     if (SafepointSynchronize::is_at_safepoint()) {
1404       guarantee(Thread::current()->is_VM_thread() ||
1405                 OldSets_lock->owned_by_self(),
1406                 "master humongous set MT safety protocol at a safepoint");
1407     } else {
1408       guarantee(Heap_lock->owned_by_self(),
1409                 "master humongous set MT safety protocol outside a safepoint");
1410     }
1411   }
1412   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1413   const char* get_description() { return "Humongous Regions"; }
1414 };
1415 
1416 G1CollectedHeap::G1CollectedHeap() :
1417   CollectedHeap(),
1418   _young_gen_sampling_thread(NULL),
1419   _workers(NULL),
1420   _card_table(NULL),
1421   _collection_pause_end(Ticks::now()),
1422   _soft_ref_policy(),
1423   _old_set("Old Region Set", new OldRegionSetChecker()),
1424   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1425   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1426   _bot(NULL),
1427   _listener(),
1428   _numa(G1NUMA::create()),
1429   _hrm(NULL),
1430   _allocator(NULL),
1431   _verifier(NULL),
1432   _summary_bytes_used(0),
1433   _bytes_used_during_gc(0),
1434   _archive_allocator(NULL),
1435   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1436   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1437   _expand_heap_after_alloc_failure(true),
1438   _g1mm(NULL),
1439   _humongous_reclaim_candidates(),
1440   _has_humongous_reclaim_candidates(false),
1441   _hr_printer(),
1442   _collector_state(),
1443   _old_marking_cycles_started(0),
1444   _old_marking_cycles_completed(0),
1445   _eden(),
1446   _survivor(),
1447   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1448   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1449   _policy(G1Policy::create_policy(_gc_timer_stw)),
1450   _heap_sizing_policy(NULL),
1451   _collection_set(this, _policy),
1452   _hot_card_cache(NULL),
1453   _rem_set(NULL),
1454   _cm(NULL),
1455   _cm_thread(NULL),
1456   _cr(NULL),
1457   _task_queues(NULL),
1458   _evacuation_failed(false),
1459   _evacuation_failed_info_array(NULL),
1460   _preserved_marks_set(true /* in_c_heap */),
1461 #ifndef PRODUCT
1462   _evacuation_failure_alot_for_current_gc(false),
1463   _evacuation_failure_alot_gc_number(0),
1464   _evacuation_failure_alot_count(0),
1465 #endif
1466   _ref_processor_stw(NULL),
1467   _is_alive_closure_stw(this),
1468   _is_subject_to_discovery_stw(this),
1469   _ref_processor_cm(NULL),
1470   _is_alive_closure_cm(this),
1471   _is_subject_to_discovery_cm(this),
1472   _region_attr() {
1473 
1474   _verifier = new G1HeapVerifier(this);
1475 
1476   _allocator = new G1Allocator(this);
1477 
1478   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1479 
1480   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1481 
1482   // Override the default _filler_array_max_size so that no humongous filler
1483   // objects are created.
1484   _filler_array_max_size = _humongous_object_threshold_in_words;
1485 
1486   uint n_queues = ParallelGCThreads;
1487   _task_queues = new G1ScannerTasksQueueSet(n_queues);
1488 
1489   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1490 
1491   for (uint i = 0; i < n_queues; i++) {
1492     G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1493     q->initialize();
1494     _task_queues->register_queue(i, q);
1495     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1496   }
1497 
1498   // Initialize the G1EvacuationFailureALot counters and flags.
1499   NOT_PRODUCT(reset_evacuation_should_fail();)
1500   _gc_tracer_stw->initialize();
1501 
1502   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1503 }
1504 
1505 static size_t actual_reserved_page_size(ReservedSpace rs) {
1506   size_t page_size = os::vm_page_size();
1507   if (UseLargePages) {
1508     // There are two ways to manage large page memory.
1509     // 1. OS supports committing large page memory.
1510     // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1511     //    And ReservedSpace calls it 'special'. If we failed to set 'special',
1512     //    we reserved memory without large page.
1513     if (os::can_commit_large_page_memory() || rs.special()) {
1514       // An alignment at ReservedSpace comes from preferred page size or
1515       // heap alignment, and if the alignment came from heap alignment, it could be
1516       // larger than large pages size. So need to cap with the large page size.
1517       page_size = MIN2(rs.alignment(), os::large_page_size());
1518     }
1519   }
1520 
1521   return page_size;
1522 }
1523 
1524 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1525                                                                  size_t size,
1526                                                                  size_t translation_factor) {
1527   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1528   // Allocate a new reserved space, preferring to use large pages.
1529   ReservedSpace rs(size, preferred_page_size);
1530   size_t page_size = actual_reserved_page_size(rs);
1531   G1RegionToSpaceMapper* result  =
1532     G1RegionToSpaceMapper::create_mapper(rs,
1533                                          size,
1534                                          page_size,
1535                                          HeapRegion::GrainBytes,
1536                                          translation_factor,
1537                                          mtGC);
1538 
1539   os::trace_page_sizes_for_requested_size(description,
1540                                           size,
1541                                           preferred_page_size,
1542                                           page_size,
1543                                           rs.base(),
1544                                           rs.size());
1545 
1546   return result;
1547 }
1548 
1549 jint G1CollectedHeap::initialize_concurrent_refinement() {
1550   jint ecode = JNI_OK;
1551   _cr = G1ConcurrentRefine::create(&ecode);
1552   return ecode;
1553 }
1554 
1555 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1556   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1557   if (_young_gen_sampling_thread->osthread() == NULL) {
1558     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1559     return JNI_ENOMEM;
1560   }
1561   return JNI_OK;
1562 }
1563 
1564 jint G1CollectedHeap::initialize() {
1565 
1566   // Necessary to satisfy locking discipline assertions.
1567 
1568   MutexLocker x(Heap_lock);
1569 
1570   // While there are no constraints in the GC code that HeapWordSize
1571   // be any particular value, there are multiple other areas in the
1572   // system which believe this to be true (e.g. oop->object_size in some
1573   // cases incorrectly returns the size in wordSize units rather than
1574   // HeapWordSize).
1575   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1576 
1577   size_t init_byte_size = InitialHeapSize;
1578   size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1579 
1580   // Ensure that the sizes are properly aligned.
1581   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1582   Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1583   Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1584 
1585   // Reserve the maximum.
1586 
1587   // When compressed oops are enabled, the preferred heap base
1588   // is calculated by subtracting the requested size from the
1589   // 32Gb boundary and using the result as the base address for
1590   // heap reservation. If the requested size is not aligned to
1591   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1592   // into the ReservedHeapSpace constructor) then the actual
1593   // base of the reserved heap may end up differing from the
1594   // address that was requested (i.e. the preferred heap base).
1595   // If this happens then we could end up using a non-optimal
1596   // compressed oops mode.
1597 
1598   ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1599                                                      HeapAlignment);
1600 
1601   initialize_reserved_region(heap_rs);
1602 
1603   // Create the barrier set for the entire reserved region.
1604   G1CardTable* ct = new G1CardTable(heap_rs.region());
1605   ct->initialize();
1606   G1BarrierSet* bs = new G1BarrierSet(ct);
1607   bs->initialize();
1608   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1609   BarrierSet::set_barrier_set(bs);
1610   _card_table = ct;
1611 
1612   {
1613     G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1614     satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1615     satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1616   }
1617 
1618   // Create the hot card cache.
1619   _hot_card_cache = new G1HotCardCache(this);
1620 
1621   // Carve out the G1 part of the heap.
1622   ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1623   size_t page_size = actual_reserved_page_size(heap_rs);
1624   G1RegionToSpaceMapper* heap_storage =
1625     G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1626                                               g1_rs.size(),
1627                                               page_size,
1628                                               HeapRegion::GrainBytes,
1629                                               1,
1630                                               mtJavaHeap);
1631   if(heap_storage == NULL) {
1632     vm_shutdown_during_initialization("Could not initialize G1 heap");
1633     return JNI_ERR;
1634   }
1635 
1636   os::trace_page_sizes("Heap",
1637                        MinHeapSize,
1638                        reserved_byte_size,
1639                        page_size,
1640                        heap_rs.base(),
1641                        heap_rs.size());
1642   heap_storage->set_mapping_changed_listener(&_listener);
1643 
1644   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1645   G1RegionToSpaceMapper* bot_storage =
1646     create_aux_memory_mapper("Block Offset Table",
1647                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1648                              G1BlockOffsetTable::heap_map_factor());
1649 
1650   G1RegionToSpaceMapper* cardtable_storage =
1651     create_aux_memory_mapper("Card Table",
1652                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1653                              G1CardTable::heap_map_factor());
1654 
1655   G1RegionToSpaceMapper* card_counts_storage =
1656     create_aux_memory_mapper("Card Counts Table",
1657                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1658                              G1CardCounts::heap_map_factor());
1659 
1660   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1661   G1RegionToSpaceMapper* prev_bitmap_storage =
1662     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1663   G1RegionToSpaceMapper* next_bitmap_storage =
1664     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1665 
1666   _hrm = HeapRegionManager::create_manager(this);
1667 
1668   _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1669   _card_table->initialize(cardtable_storage);
1670 
1671   // Do later initialization work for concurrent refinement.
1672   _hot_card_cache->initialize(card_counts_storage);
1673 
1674   // 6843694 - ensure that the maximum region index can fit
1675   // in the remembered set structures.
1676   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1677   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1678 
1679   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1680   // start within the first card.
1681   guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1682   // Also create a G1 rem set.
1683   _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1684   _rem_set->initialize(max_reserved_capacity(), max_regions());
1685 
1686   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1687   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1688   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1689             "too many cards per region");
1690 
1691   FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1692 
1693   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1694 
1695   {
1696     HeapWord* start = _hrm->reserved().start();
1697     HeapWord* end = _hrm->reserved().end();
1698     size_t granularity = HeapRegion::GrainBytes;
1699 
1700     _region_attr.initialize(start, end, granularity);
1701     _humongous_reclaim_candidates.initialize(start, end, granularity);
1702   }
1703 
1704   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1705                           true /* are_GC_task_threads */,
1706                           false /* are_ConcurrentGC_threads */);
1707   if (_workers == NULL) {
1708     return JNI_ENOMEM;
1709   }
1710   _workers->initialize_workers();
1711 
1712   _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1713 
1714   // Create the G1ConcurrentMark data structure and thread.
1715   // (Must do this late, so that "max_regions" is defined.)
1716   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1717   _cm_thread = _cm->cm_thread();
1718 
1719   // Now expand into the initial heap size.
1720   if (!expand(init_byte_size, _workers)) {
1721     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1722     return JNI_ENOMEM;
1723   }
1724 
1725   // Perform any initialization actions delegated to the policy.
1726   policy()->init(this, &_collection_set);
1727 
1728   jint ecode = initialize_concurrent_refinement();
1729   if (ecode != JNI_OK) {
1730     return ecode;
1731   }
1732 
1733   ecode = initialize_young_gen_sampling_thread();
1734   if (ecode != JNI_OK) {
1735     return ecode;
1736   }
1737 
1738   {
1739     G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1740     dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1741     dcqs.set_max_cards(concurrent_refine()->red_zone());
1742   }
1743 
1744   // Here we allocate the dummy HeapRegion that is required by the
1745   // G1AllocRegion class.
1746   HeapRegion* dummy_region = _hrm->get_dummy_region();
1747 
1748   // We'll re-use the same region whether the alloc region will
1749   // require BOT updates or not and, if it doesn't, then a non-young
1750   // region will complain that it cannot support allocations without
1751   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1752   dummy_region->set_eden();
1753   // Make sure it's full.
1754   dummy_region->set_top(dummy_region->end());
1755   G1AllocRegion::setup(this, dummy_region);
1756 
1757   _allocator->init_mutator_alloc_regions();
1758 
1759   // Do create of the monitoring and management support so that
1760   // values in the heap have been properly initialized.
1761   _g1mm = new G1MonitoringSupport(this);
1762 
1763   G1StringDedup::initialize();
1764 
1765   _preserved_marks_set.init(ParallelGCThreads);
1766 
1767   _collection_set.initialize(max_regions());
1768 
1769   G1InitLogger::print();
1770 
1771   return JNI_OK;
1772 }
1773 
1774 void G1CollectedHeap::stop() {
1775   // Stop all concurrent threads. We do this to make sure these threads
1776   // do not continue to execute and access resources (e.g. logging)
1777   // that are destroyed during shutdown.
1778   _cr->stop();
1779   _young_gen_sampling_thread->stop();
1780   _cm_thread->stop();
1781   if (G1StringDedup::is_enabled()) {
1782     G1StringDedup::stop();
1783   }
1784 }
1785 
1786 void G1CollectedHeap::safepoint_synchronize_begin() {
1787   SuspendibleThreadSet::synchronize();
1788 }
1789 
1790 void G1CollectedHeap::safepoint_synchronize_end() {
1791   SuspendibleThreadSet::desynchronize();
1792 }
1793 
1794 void G1CollectedHeap::post_initialize() {
1795   CollectedHeap::post_initialize();
1796   ref_processing_init();
1797 }
1798 
1799 void G1CollectedHeap::ref_processing_init() {
1800   // Reference processing in G1 currently works as follows:
1801   //
1802   // * There are two reference processor instances. One is
1803   //   used to record and process discovered references
1804   //   during concurrent marking; the other is used to
1805   //   record and process references during STW pauses
1806   //   (both full and incremental).
1807   // * Both ref processors need to 'span' the entire heap as
1808   //   the regions in the collection set may be dotted around.
1809   //
1810   // * For the concurrent marking ref processor:
1811   //   * Reference discovery is enabled at concurrent start.
1812   //   * Reference discovery is disabled and the discovered
1813   //     references processed etc during remarking.
1814   //   * Reference discovery is MT (see below).
1815   //   * Reference discovery requires a barrier (see below).
1816   //   * Reference processing may or may not be MT
1817   //     (depending on the value of ParallelRefProcEnabled
1818   //     and ParallelGCThreads).
1819   //   * A full GC disables reference discovery by the CM
1820   //     ref processor and abandons any entries on it's
1821   //     discovered lists.
1822   //
1823   // * For the STW processor:
1824   //   * Non MT discovery is enabled at the start of a full GC.
1825   //   * Processing and enqueueing during a full GC is non-MT.
1826   //   * During a full GC, references are processed after marking.
1827   //
1828   //   * Discovery (may or may not be MT) is enabled at the start
1829   //     of an incremental evacuation pause.
1830   //   * References are processed near the end of a STW evacuation pause.
1831   //   * For both types of GC:
1832   //     * Discovery is atomic - i.e. not concurrent.
1833   //     * Reference discovery will not need a barrier.
1834 
1835   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1836 
1837   // Concurrent Mark ref processor
1838   _ref_processor_cm =
1839     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1840                            mt_processing,                                  // mt processing
1841                            ParallelGCThreads,                              // degree of mt processing
1842                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1843                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1844                            false,                                          // Reference discovery is not atomic
1845                            &_is_alive_closure_cm,                          // is alive closure
1846                            true);                                          // allow changes to number of processing threads
1847 
1848   // STW ref processor
1849   _ref_processor_stw =
1850     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1851                            mt_processing,                        // mt processing
1852                            ParallelGCThreads,                    // degree of mt processing
1853                            (ParallelGCThreads > 1),              // mt discovery
1854                            ParallelGCThreads,                    // degree of mt discovery
1855                            true,                                 // Reference discovery is atomic
1856                            &_is_alive_closure_stw,               // is alive closure
1857                            true);                                // allow changes to number of processing threads
1858 }
1859 
1860 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1861   return &_soft_ref_policy;
1862 }
1863 
1864 size_t G1CollectedHeap::capacity() const {
1865   return _hrm->length() * HeapRegion::GrainBytes;
1866 }
1867 
1868 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1869   return _hrm->total_free_bytes();
1870 }
1871 
1872 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1873   _hot_card_cache->drain(cl, worker_id);
1874 }
1875 
1876 // Computes the sum of the storage used by the various regions.
1877 size_t G1CollectedHeap::used() const {
1878   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1879   if (_archive_allocator != NULL) {
1880     result += _archive_allocator->used();
1881   }
1882   return result;
1883 }
1884 
1885 size_t G1CollectedHeap::used_unlocked() const {
1886   return _summary_bytes_used;
1887 }
1888 
1889 class SumUsedClosure: public HeapRegionClosure {
1890   size_t _used;
1891 public:
1892   SumUsedClosure() : _used(0) {}
1893   bool do_heap_region(HeapRegion* r) {
1894     _used += r->used();
1895     return false;
1896   }
1897   size_t result() { return _used; }
1898 };
1899 
1900 size_t G1CollectedHeap::recalculate_used() const {
1901   SumUsedClosure blk;
1902   heap_region_iterate(&blk);
1903   return blk.result();
1904 }
1905 
1906 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1907   switch (cause) {
1908     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1909     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1910     case GCCause::_wb_conc_mark:                        return true;
1911     default :                                           return false;
1912   }
1913 }
1914 
1915 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1916   switch (cause) {
1917     case GCCause::_g1_humongous_allocation: return true;
1918     case GCCause::_g1_periodic_collection:  return G1PeriodicGCInvokesConcurrent;
1919     case GCCause::_wb_breakpoint:           return true;
1920     default:                                return is_user_requested_concurrent_full_gc(cause);
1921   }
1922 }
1923 
1924 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
1925   if (policy()->force_upgrade_to_full()) {
1926     return true;
1927   } else if (should_do_concurrent_full_gc(_gc_cause)) {
1928     return false;
1929   } else if (has_regions_left_for_allocation()) {
1930     return false;
1931   } else {
1932     return true;
1933   }
1934 }
1935 
1936 #ifndef PRODUCT
1937 void G1CollectedHeap::allocate_dummy_regions() {
1938   // Let's fill up most of the region
1939   size_t word_size = HeapRegion::GrainWords - 1024;
1940   // And as a result the region we'll allocate will be humongous.
1941   guarantee(is_humongous(word_size), "sanity");
1942 
1943   // _filler_array_max_size is set to humongous object threshold
1944   // but temporarily change it to use CollectedHeap::fill_with_object().
1945   AutoModifyRestore<size_t> temporarily(_filler_array_max_size, word_size);
1946 
1947   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1948     // Let's use the existing mechanism for the allocation
1949     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1950     if (dummy_obj != NULL) {
1951       MemRegion mr(dummy_obj, word_size);
1952       CollectedHeap::fill_with_object(mr);
1953     } else {
1954       // If we can't allocate once, we probably cannot allocate
1955       // again. Let's get out of the loop.
1956       break;
1957     }
1958   }
1959 }
1960 #endif // !PRODUCT
1961 
1962 void G1CollectedHeap::increment_old_marking_cycles_started() {
1963   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1964          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1965          "Wrong marking cycle count (started: %d, completed: %d)",
1966          _old_marking_cycles_started, _old_marking_cycles_completed);
1967 
1968   _old_marking_cycles_started++;
1969 }
1970 
1971 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1972                                                              bool whole_heap_examined) {
1973   MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1974 
1975   // We assume that if concurrent == true, then the caller is a
1976   // concurrent thread that was joined the Suspendible Thread
1977   // Set. If there's ever a cheap way to check this, we should add an
1978   // assert here.
1979 
1980   // Given that this method is called at the end of a Full GC or of a
1981   // concurrent cycle, and those can be nested (i.e., a Full GC can
1982   // interrupt a concurrent cycle), the number of full collections
1983   // completed should be either one (in the case where there was no
1984   // nesting) or two (when a Full GC interrupted a concurrent cycle)
1985   // behind the number of full collections started.
1986 
1987   // This is the case for the inner caller, i.e. a Full GC.
1988   assert(concurrent ||
1989          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1990          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1991          "for inner caller (Full GC): _old_marking_cycles_started = %u "
1992          "is inconsistent with _old_marking_cycles_completed = %u",
1993          _old_marking_cycles_started, _old_marking_cycles_completed);
1994 
1995   // This is the case for the outer caller, i.e. the concurrent cycle.
1996   assert(!concurrent ||
1997          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1998          "for outer caller (concurrent cycle): "
1999          "_old_marking_cycles_started = %u "
2000          "is inconsistent with _old_marking_cycles_completed = %u",
2001          _old_marking_cycles_started, _old_marking_cycles_completed);
2002 
2003   _old_marking_cycles_completed += 1;
2004   if (whole_heap_examined) {
2005     // Signal that we have completed a visit to all live objects.
2006     record_whole_heap_examined_timestamp();
2007   }
2008 
2009   // We need to clear the "in_progress" flag in the CM thread before
2010   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2011   // is set) so that if a waiter requests another System.gc() it doesn't
2012   // incorrectly see that a marking cycle is still in progress.
2013   if (concurrent) {
2014     _cm_thread->set_idle();
2015   }
2016 
2017   // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2018   // for a full GC to finish that their wait is over.
2019   ml.notify_all();
2020 }
2021 
2022 void G1CollectedHeap::collect(GCCause::Cause cause) {
2023   try_collect(cause);
2024 }
2025 
2026 // Return true if (x < y) with allowance for wraparound.
2027 static bool gc_counter_less_than(uint x, uint y) {
2028   return (x - y) > (UINT_MAX/2);
2029 }
2030 
2031 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2032 // Macro so msg printing is format-checked.
2033 #define LOG_COLLECT_CONCURRENTLY(cause, ...)                            \
2034   do {                                                                  \
2035     LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt;                   \
2036     if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) {                     \
2037       ResourceMark rm; /* For thread name. */                           \
2038       LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2039       LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2040                                        Thread::current()->name(),       \
2041                                        GCCause::to_string(cause));      \
2042       LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__);                    \
2043     }                                                                   \
2044   } while (0)
2045 
2046 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2047   LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2048 
2049 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2050                                                uint gc_counter,
2051                                                uint old_marking_started_before) {
2052   assert_heap_not_locked();
2053   assert(should_do_concurrent_full_gc(cause),
2054          "Non-concurrent cause %s", GCCause::to_string(cause));
2055 
2056   for (uint i = 1; true; ++i) {
2057     // Try to schedule concurrent start evacuation pause that will
2058     // start a concurrent cycle.
2059     LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2060     VM_G1TryInitiateConcMark op(gc_counter,
2061                                 cause,
2062                                 policy()->max_pause_time_ms());
2063     VMThread::execute(&op);
2064 
2065     // Request is trivially finished.
2066     if (cause == GCCause::_g1_periodic_collection) {
2067       LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2068       return op.gc_succeeded();
2069     }
2070 
2071     // If VMOp skipped initiating concurrent marking cycle because
2072     // we're terminating, then we're done.
2073     if (op.terminating()) {
2074       LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2075       return false;
2076     }
2077 
2078     // Lock to get consistent set of values.
2079     uint old_marking_started_after;
2080     uint old_marking_completed_after;
2081     {
2082       MutexLocker ml(Heap_lock);
2083       // Update gc_counter for retrying VMOp if needed. Captured here to be
2084       // consistent with the values we use below for termination tests.  If
2085       // a retry is needed after a possible wait, and another collection
2086       // occurs in the meantime, it will cause our retry to be skipped and
2087       // we'll recheck for termination with updated conditions from that
2088       // more recent collection.  That's what we want, rather than having
2089       // our retry possibly perform an unnecessary collection.
2090       gc_counter = total_collections();
2091       old_marking_started_after = _old_marking_cycles_started;
2092       old_marking_completed_after = _old_marking_cycles_completed;
2093     }
2094 
2095     if (cause == GCCause::_wb_breakpoint) {
2096       if (op.gc_succeeded()) {
2097         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2098         return true;
2099       }
2100       // When _wb_breakpoint there can't be another cycle or deferred.
2101       assert(!op.cycle_already_in_progress(), "invariant");
2102       assert(!op.whitebox_attached(), "invariant");
2103       // Concurrent cycle attempt might have been cancelled by some other
2104       // collection, so retry.  Unlike other cases below, we want to retry
2105       // even if cancelled by a STW full collection, because we really want
2106       // to start a concurrent cycle.
2107       if (old_marking_started_before != old_marking_started_after) {
2108         LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2109         old_marking_started_before = old_marking_started_after;
2110       }
2111     } else if (!GCCause::is_user_requested_gc(cause)) {
2112       // For an "automatic" (not user-requested) collection, we just need to
2113       // ensure that progress is made.
2114       //
2115       // Request is finished if any of
2116       // (1) the VMOp successfully performed a GC,
2117       // (2) a concurrent cycle was already in progress,
2118       // (3) whitebox is controlling concurrent cycles,
2119       // (4) a new cycle was started (by this thread or some other), or
2120       // (5) a Full GC was performed.
2121       // Cases (4) and (5) are detected together by a change to
2122       // _old_marking_cycles_started.
2123       //
2124       // Note that (1) does not imply (4).  If we're still in the mixed
2125       // phase of an earlier concurrent collection, the request to make the
2126       // collection a concurrent start won't be honored.  If we don't check for
2127       // both conditions we'll spin doing back-to-back collections.
2128       if (op.gc_succeeded() ||
2129           op.cycle_already_in_progress() ||
2130           op.whitebox_attached() ||
2131           (old_marking_started_before != old_marking_started_after)) {
2132         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2133         return true;
2134       }
2135     } else {                    // User-requested GC.
2136       // For a user-requested collection, we want to ensure that a complete
2137       // full collection has been performed before returning, but without
2138       // waiting for more than needed.
2139 
2140       // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2141       // new cycle was started.  That's good, because it's not clear what we
2142       // should do otherwise.  Trying again just does back to back GCs.
2143       // Can't wait for someone else to start a cycle.  And returning fails
2144       // to meet the goal of ensuring a full collection was performed.
2145       assert(!op.gc_succeeded() ||
2146              (old_marking_started_before != old_marking_started_after),
2147              "invariant: succeeded %s, started before %u, started after %u",
2148              BOOL_TO_STR(op.gc_succeeded()),
2149              old_marking_started_before, old_marking_started_after);
2150 
2151       // Request is finished if a full collection (concurrent or stw)
2152       // was started after this request and has completed, e.g.
2153       // started_before < completed_after.
2154       if (gc_counter_less_than(old_marking_started_before,
2155                                old_marking_completed_after)) {
2156         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2157         return true;
2158       }
2159 
2160       if (old_marking_started_after != old_marking_completed_after) {
2161         // If there is an in-progress cycle (possibly started by us), then
2162         // wait for that cycle to complete, e.g.
2163         // while completed_now < started_after.
2164         LOG_COLLECT_CONCURRENTLY(cause, "wait");
2165         MonitorLocker ml(G1OldGCCount_lock);
2166         while (gc_counter_less_than(_old_marking_cycles_completed,
2167                                     old_marking_started_after)) {
2168           ml.wait();
2169         }
2170         // Request is finished if the collection we just waited for was
2171         // started after this request.
2172         if (old_marking_started_before != old_marking_started_after) {
2173           LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2174           return true;
2175         }
2176       }
2177 
2178       // If VMOp was successful then it started a new cycle that the above
2179       // wait &etc should have recognized as finishing this request.  This
2180       // differs from a non-user-request, where gc_succeeded does not imply
2181       // a new cycle was started.
2182       assert(!op.gc_succeeded(), "invariant");
2183 
2184       if (op.cycle_already_in_progress()) {
2185         // If VMOp failed because a cycle was already in progress, it
2186         // is now complete.  But it didn't finish this user-requested
2187         // GC, so try again.
2188         LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2189         continue;
2190       } else if (op.whitebox_attached()) {
2191         // If WhiteBox wants control, wait for notification of a state
2192         // change in the controller, then try again.  Don't wait for
2193         // release of control, since collections may complete while in
2194         // control.  Note: This won't recognize a STW full collection
2195         // while waiting; we can't wait on multiple monitors.
2196         LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2197         MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2198         if (ConcurrentGCBreakpoints::is_controlled()) {
2199           ml.wait();
2200         }
2201         continue;
2202       }
2203     }
2204 
2205     // Collection failed and should be retried.
2206     assert(op.transient_failure(), "invariant");
2207 
2208     if (GCLocker::is_active_and_needs_gc()) {
2209       // If GCLocker is active, wait until clear before retrying.
2210       LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2211       GCLocker::stall_until_clear();
2212     }
2213 
2214     LOG_COLLECT_CONCURRENTLY(cause, "retry");
2215   }
2216 }
2217 
2218 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2219   assert_heap_not_locked();
2220 
2221   // Lock to get consistent set of values.
2222   uint gc_count_before;
2223   uint full_gc_count_before;
2224   uint old_marking_started_before;
2225   {
2226     MutexLocker ml(Heap_lock);
2227     gc_count_before = total_collections();
2228     full_gc_count_before = total_full_collections();
2229     old_marking_started_before = _old_marking_cycles_started;
2230   }
2231 
2232   if (should_do_concurrent_full_gc(cause)) {
2233     return try_collect_concurrently(cause,
2234                                     gc_count_before,
2235                                     old_marking_started_before);
2236   } else if (GCLocker::should_discard(cause, gc_count_before)) {
2237     // Indicate failure to be consistent with VMOp failure due to
2238     // another collection slipping in after our gc_count but before
2239     // our request is processed.
2240     return false;
2241   } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2242              DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2243 
2244     // Schedule a standard evacuation pause. We're setting word_size
2245     // to 0 which means that we are not requesting a post-GC allocation.
2246     VM_G1CollectForAllocation op(0,     /* word_size */
2247                                  gc_count_before,
2248                                  cause,
2249                                  policy()->max_pause_time_ms());
2250     VMThread::execute(&op);
2251     return op.gc_succeeded();
2252   } else {
2253     // Schedule a Full GC.
2254     VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2255     VMThread::execute(&op);
2256     return op.gc_succeeded();
2257   }
2258 }
2259 
2260 bool G1CollectedHeap::is_in(const void* p) const {
2261   if (_hrm->reserved().contains(p)) {
2262     // Given that we know that p is in the reserved space,
2263     // heap_region_containing() should successfully
2264     // return the containing region.
2265     HeapRegion* hr = heap_region_containing(p);
2266     return hr->is_in(p);
2267   } else {
2268     return false;
2269   }
2270 }
2271 
2272 #ifdef ASSERT
2273 bool G1CollectedHeap::is_in_exact(const void* p) const {
2274   bool contains = reserved_region().contains(p);
2275   bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2276   if (contains && available) {
2277     return true;
2278   } else {
2279     return false;
2280   }
2281 }
2282 #endif
2283 
2284 // Iteration functions.
2285 
2286 // Iterates an ObjectClosure over all objects within a HeapRegion.
2287 
2288 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2289   ObjectClosure* _cl;
2290 public:
2291   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2292   bool do_heap_region(HeapRegion* r) {
2293     if (!r->is_continues_humongous()) {
2294       r->object_iterate(_cl);
2295     }
2296     return false;
2297   }
2298 };
2299 
2300 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2301   IterateObjectClosureRegionClosure blk(cl);
2302   heap_region_iterate(&blk);
2303 }
2304 
2305 class G1ParallelObjectIterator : public ParallelObjectIterator {
2306 private:
2307   G1CollectedHeap*  _heap;
2308   HeapRegionClaimer _claimer;
2309 
2310 public:
2311   G1ParallelObjectIterator(uint thread_num) :
2312       _heap(G1CollectedHeap::heap()),
2313       _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2314 
2315   virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2316     _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2317   }
2318 };
2319 
2320 ParallelObjectIterator* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2321   return new G1ParallelObjectIterator(thread_num);
2322 }
2323 
2324 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2325   IterateObjectClosureRegionClosure blk(cl);
2326   heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2327 }
2328 
2329 void G1CollectedHeap::keep_alive(oop obj) {
2330   G1BarrierSet::enqueue(obj);
2331 }
2332 
2333 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2334   _hrm->iterate(cl);
2335 }
2336 
2337 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2338                                                                  HeapRegionClaimer *hrclaimer,
2339                                                                  uint worker_id) const {
2340   _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2341 }
2342 
2343 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2344                                                          HeapRegionClaimer *hrclaimer) const {
2345   _hrm->par_iterate(cl, hrclaimer, 0);
2346 }
2347 
2348 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2349   _collection_set.iterate(cl);
2350 }
2351 
2352 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2353   _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2354 }
2355 
2356 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2357   _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2358 }
2359 
2360 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2361   HeapRegion* hr = heap_region_containing(addr);
2362   return hr->block_start(addr);
2363 }
2364 
2365 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2366   HeapRegion* hr = heap_region_containing(addr);
2367   return hr->block_is_obj(addr);
2368 }
2369 
2370 bool G1CollectedHeap::supports_tlab_allocation() const {
2371   return true;
2372 }
2373 
2374 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2375   return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2376 }
2377 
2378 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2379   return _eden.length() * HeapRegion::GrainBytes;
2380 }
2381 
2382 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2383 // must be equal to the humongous object limit.
2384 size_t G1CollectedHeap::max_tlab_size() const {
2385   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2386 }
2387 
2388 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2389   return _allocator->unsafe_max_tlab_alloc();
2390 }
2391 
2392 size_t G1CollectedHeap::max_capacity() const {
2393   return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2394 }
2395 
2396 size_t G1CollectedHeap::max_reserved_capacity() const {
2397   return _hrm->max_length() * HeapRegion::GrainBytes;
2398 }
2399 
2400 void G1CollectedHeap::deduplicate_string(oop str) {
2401   assert(java_lang_String::is_instance(str), "invariant");
2402 
2403   if (G1StringDedup::is_enabled()) {
2404     G1StringDedup::deduplicate(str);
2405   }
2406 }
2407 
2408 void G1CollectedHeap::prepare_for_verify() {
2409   _verifier->prepare_for_verify();
2410 }
2411 
2412 void G1CollectedHeap::verify(VerifyOption vo) {
2413   _verifier->verify(vo);
2414 }
2415 
2416 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2417   return true;
2418 }
2419 
2420 bool G1CollectedHeap::is_heterogeneous_heap() const {
2421   return G1Arguments::is_heterogeneous_heap();
2422 }
2423 
2424 class PrintRegionClosure: public HeapRegionClosure {
2425   outputStream* _st;
2426 public:
2427   PrintRegionClosure(outputStream* st) : _st(st) {}
2428   bool do_heap_region(HeapRegion* r) {
2429     r->print_on(_st);
2430     return false;
2431   }
2432 };
2433 
2434 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2435                                        const HeapRegion* hr,
2436                                        const VerifyOption vo) const {
2437   switch (vo) {
2438   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2439   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2440   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2441   default:                            ShouldNotReachHere();
2442   }
2443   return false; // keep some compilers happy
2444 }
2445 
2446 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2447                                        const VerifyOption vo) const {
2448   switch (vo) {
2449   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2450   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2451   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2452   default:                            ShouldNotReachHere();
2453   }
2454   return false; // keep some compilers happy
2455 }
2456 
2457 void G1CollectedHeap::print_heap_regions() const {
2458   LogTarget(Trace, gc, heap, region) lt;
2459   if (lt.is_enabled()) {
2460     LogStream ls(lt);
2461     print_regions_on(&ls);
2462   }
2463 }
2464 
2465 void G1CollectedHeap::print_on(outputStream* st) const {
2466   st->print(" %-20s", "garbage-first heap");
2467   if (_hrm != NULL) {
2468     st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2469               capacity()/K, used_unlocked()/K);
2470     st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2471               p2i(_hrm->reserved().start()),
2472               p2i(_hrm->reserved().end()));
2473   }
2474   st->cr();
2475   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2476   uint young_regions = young_regions_count();
2477   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2478             (size_t) young_regions * HeapRegion::GrainBytes / K);
2479   uint survivor_regions = survivor_regions_count();
2480   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2481             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2482   st->cr();
2483   if (_numa->is_enabled()) {
2484     uint num_nodes = _numa->num_active_nodes();
2485     st->print("  remaining free region(s) on each NUMA node: ");
2486     const int* node_ids = _numa->node_ids();
2487     for (uint node_index = 0; node_index < num_nodes; node_index++) {
2488       uint num_free_regions = (_hrm != NULL ? _hrm->num_free_regions(node_index) : 0);
2489       st->print("%d=%u ", node_ids[node_index], num_free_regions);
2490     }
2491     st->cr();
2492   }
2493   MetaspaceUtils::print_on(st);
2494 }
2495 
2496 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2497   if (_hrm == NULL) {
2498     return;
2499   }
2500 
2501   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2502                "HS=humongous(starts), HC=humongous(continues), "
2503                "CS=collection set, F=free, "
2504                "OA=open archive, CA=closed archive, "
2505                "TAMS=top-at-mark-start (previous, next)");
2506   PrintRegionClosure blk(st);
2507   heap_region_iterate(&blk);
2508 }
2509 
2510 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2511   print_on(st);
2512 
2513   // Print the per-region information.
2514   if (_hrm != NULL) {
2515     st->cr();
2516     print_regions_on(st);
2517   }
2518 }
2519 
2520 void G1CollectedHeap::print_on_error(outputStream* st) const {
2521   this->CollectedHeap::print_on_error(st);
2522 
2523   if (_cm != NULL) {
2524     st->cr();
2525     _cm->print_on_error(st);
2526   }
2527 }
2528 
2529 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2530   workers()->threads_do(tc);
2531   tc->do_thread(_cm_thread);
2532   _cm->threads_do(tc);
2533   _cr->threads_do(tc);
2534   tc->do_thread(_young_gen_sampling_thread);
2535   if (G1StringDedup::is_enabled()) {
2536     G1StringDedup::threads_do(tc);
2537   }
2538 }
2539 
2540 void G1CollectedHeap::print_tracing_info() const {
2541   rem_set()->print_summary_info();
2542   concurrent_mark()->print_summary_info();
2543 }
2544 
2545 #ifndef PRODUCT
2546 // Helpful for debugging RSet issues.
2547 
2548 class PrintRSetsClosure : public HeapRegionClosure {
2549 private:
2550   const char* _msg;
2551   size_t _occupied_sum;
2552 
2553 public:
2554   bool do_heap_region(HeapRegion* r) {
2555     HeapRegionRemSet* hrrs = r->rem_set();
2556     size_t occupied = hrrs->occupied();
2557     _occupied_sum += occupied;
2558 
2559     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2560     if (occupied == 0) {
2561       tty->print_cr("  RSet is empty");
2562     } else {
2563       hrrs->print();
2564     }
2565     tty->print_cr("----------");
2566     return false;
2567   }
2568 
2569   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2570     tty->cr();
2571     tty->print_cr("========================================");
2572     tty->print_cr("%s", msg);
2573     tty->cr();
2574   }
2575 
2576   ~PrintRSetsClosure() {
2577     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2578     tty->print_cr("========================================");
2579     tty->cr();
2580   }
2581 };
2582 
2583 void G1CollectedHeap::print_cset_rsets() {
2584   PrintRSetsClosure cl("Printing CSet RSets");
2585   collection_set_iterate_all(&cl);
2586 }
2587 
2588 void G1CollectedHeap::print_all_rsets() {
2589   PrintRSetsClosure cl("Printing All RSets");;
2590   heap_region_iterate(&cl);
2591 }
2592 #endif // PRODUCT
2593 
2594 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2595   return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2596 }
2597 
2598 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2599 
2600   size_t eden_used_bytes = _eden.used_bytes();
2601   size_t survivor_used_bytes = _survivor.used_bytes();
2602   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2603 
2604   size_t eden_capacity_bytes =
2605     (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2606 
2607   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2608   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2609                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2610 }
2611 
2612 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2613   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2614                        stats->unused(), stats->used(), stats->region_end_waste(),
2615                        stats->regions_filled(), stats->direct_allocated(),
2616                        stats->failure_used(), stats->failure_waste());
2617 }
2618 
2619 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2620   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2621   gc_tracer->report_gc_heap_summary(when, heap_summary);
2622 
2623   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2624   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2625 }
2626 
2627 void G1CollectedHeap::gc_prologue(bool full) {
2628   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2629 
2630   // This summary needs to be printed before incrementing total collections.
2631   rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2632 
2633   // Update common counters.
2634   increment_total_collections(full /* full gc */);
2635   if (full || collector_state()->in_concurrent_start_gc()) {
2636     increment_old_marking_cycles_started();
2637   }
2638 
2639   // Fill TLAB's and such
2640   {
2641     Ticks start = Ticks::now();
2642     ensure_parsability(true);
2643     Tickspan dt = Ticks::now() - start;
2644     phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS);
2645   }
2646 
2647   if (!full) {
2648     // Flush dirty card queues to qset, so later phases don't need to account
2649     // for partially filled per-thread queues and such.  Not needed for full
2650     // collections, which ignore those logs.
2651     Ticks start = Ticks::now();
2652     G1BarrierSet::dirty_card_queue_set().concatenate_logs();
2653     Tickspan dt = Ticks::now() - start;
2654     phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS);
2655   }
2656 }
2657 
2658 void G1CollectedHeap::gc_epilogue(bool full) {
2659   // Update common counters.
2660   if (full) {
2661     // Update the number of full collections that have been completed.
2662     increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2663   }
2664 
2665   // We are at the end of the GC. Total collections has already been increased.
2666   rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2667 
2668   // FIXME: what is this about?
2669   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2670   // is set.
2671 #if COMPILER2_OR_JVMCI
2672   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2673 #endif
2674 
2675   double start = os::elapsedTime();
2676   resize_all_tlabs();
2677   phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2678 
2679   MemoryService::track_memory_usage();
2680   // We have just completed a GC. Update the soft reference
2681   // policy with the new heap occupancy
2682   Universe::update_heap_info_at_gc();
2683 
2684   // Print NUMA statistics.
2685   _numa->print_statistics();
2686 
2687   _collection_pause_end = Ticks::now();
2688 }
2689 
2690 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2691   LogTarget(Trace, gc, heap, verify) lt;
2692 
2693   if (lt.is_enabled()) {
2694     LogStream ls(lt);
2695     // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2696     G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2697     heap_region_iterate(&cl);
2698   }
2699 }
2700 
2701 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2702                                                uint gc_count_before,
2703                                                bool* succeeded,
2704                                                GCCause::Cause gc_cause) {
2705   assert_heap_not_locked_and_not_at_safepoint();
2706   VM_G1CollectForAllocation op(word_size,
2707                                gc_count_before,
2708                                gc_cause,
2709                                policy()->max_pause_time_ms());
2710   VMThread::execute(&op);
2711 
2712   HeapWord* result = op.result();
2713   bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2714   assert(result == NULL || ret_succeeded,
2715          "the result should be NULL if the VM did not succeed");
2716   *succeeded = ret_succeeded;
2717 
2718   assert_heap_not_locked();
2719   return result;
2720 }
2721 
2722 void G1CollectedHeap::do_concurrent_mark() {
2723   MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2724   if (!_cm_thread->in_progress()) {
2725     _cm_thread->set_started();
2726     CGC_lock->notify();
2727   }
2728 }
2729 
2730 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2731   // We don't nominate objects with many remembered set entries, on
2732   // the assumption that such objects are likely still live.
2733   HeapRegionRemSet* rem_set = r->rem_set();
2734 
2735   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2736          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2737          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2738 }
2739 
2740 #ifndef PRODUCT
2741 void G1CollectedHeap::verify_region_attr_remset_update() {
2742   class VerifyRegionAttrRemSet : public HeapRegionClosure {
2743   public:
2744     virtual bool do_heap_region(HeapRegion* r) {
2745       G1CollectedHeap* g1h = G1CollectedHeap::heap();
2746       bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2747       assert(r->rem_set()->is_tracked() == needs_remset_update,
2748              "Region %u remset tracking status (%s) different to region attribute (%s)",
2749              r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2750       return false;
2751     }
2752   } cl;
2753   heap_region_iterate(&cl);
2754 }
2755 #endif
2756 
2757 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2758   public:
2759     bool do_heap_region(HeapRegion* hr) {
2760       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2761         hr->verify_rem_set();
2762       }
2763       return false;
2764     }
2765 };
2766 
2767 uint G1CollectedHeap::num_task_queues() const {
2768   return _task_queues->size();
2769 }
2770 
2771 #if TASKQUEUE_STATS
2772 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2773   st->print_raw_cr("GC Task Stats");
2774   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2775   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2776 }
2777 
2778 void G1CollectedHeap::print_taskqueue_stats() const {
2779   if (!log_is_enabled(Trace, gc, task, stats)) {
2780     return;
2781   }
2782   Log(gc, task, stats) log;
2783   ResourceMark rm;
2784   LogStream ls(log.trace());
2785   outputStream* st = &ls;
2786 
2787   print_taskqueue_stats_hdr(st);
2788 
2789   TaskQueueStats totals;
2790   const uint n = num_task_queues();
2791   for (uint i = 0; i < n; ++i) {
2792     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2793     totals += task_queue(i)->stats;
2794   }
2795   st->print_raw("tot "); totals.print(st); st->cr();
2796 
2797   DEBUG_ONLY(totals.verify());
2798 }
2799 
2800 void G1CollectedHeap::reset_taskqueue_stats() {
2801   const uint n = num_task_queues();
2802   for (uint i = 0; i < n; ++i) {
2803     task_queue(i)->stats.reset();
2804   }
2805 }
2806 #endif // TASKQUEUE_STATS
2807 
2808 void G1CollectedHeap::wait_for_root_region_scanning() {
2809   double scan_wait_start = os::elapsedTime();
2810   // We have to wait until the CM threads finish scanning the
2811   // root regions as it's the only way to ensure that all the
2812   // objects on them have been correctly scanned before we start
2813   // moving them during the GC.
2814   bool waited = _cm->root_regions()->wait_until_scan_finished();
2815   double wait_time_ms = 0.0;
2816   if (waited) {
2817     double scan_wait_end = os::elapsedTime();
2818     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2819   }
2820   phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2821 }
2822 
2823 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2824 private:
2825   G1HRPrinter* _hr_printer;
2826 public:
2827   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2828 
2829   virtual bool do_heap_region(HeapRegion* r) {
2830     _hr_printer->cset(r);
2831     return false;
2832   }
2833 };
2834 
2835 void G1CollectedHeap::start_new_collection_set() {
2836   double start = os::elapsedTime();
2837 
2838   collection_set()->start_incremental_building();
2839 
2840   clear_region_attr();
2841 
2842   guarantee(_eden.length() == 0, "eden should have been cleared");
2843   policy()->transfer_survivors_to_cset(survivor());
2844 
2845   // We redo the verification but now wrt to the new CSet which
2846   // has just got initialized after the previous CSet was freed.
2847   _cm->verify_no_collection_set_oops();
2848 
2849   phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2850 }
2851 
2852 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2853 
2854   _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2855   evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2856                                             collection_set()->optional_region_length());
2857 
2858   _cm->verify_no_collection_set_oops();
2859 
2860   if (_hr_printer.is_active()) {
2861     G1PrintCollectionSetClosure cl(&_hr_printer);
2862     _collection_set.iterate(&cl);
2863     _collection_set.iterate_optional(&cl);
2864   }
2865 }
2866 
2867 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2868   if (collector_state()->in_concurrent_start_gc()) {
2869     return G1HeapVerifier::G1VerifyConcurrentStart;
2870   } else if (collector_state()->in_young_only_phase()) {
2871     return G1HeapVerifier::G1VerifyYoungNormal;
2872   } else {
2873     return G1HeapVerifier::G1VerifyMixed;
2874   }
2875 }
2876 
2877 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2878   if (VerifyRememberedSets) {
2879     log_info(gc, verify)("[Verifying RemSets before GC]");
2880     VerifyRegionRemSetClosure v_cl;
2881     heap_region_iterate(&v_cl);
2882   }
2883   _verifier->verify_before_gc(type);
2884   _verifier->check_bitmaps("GC Start");
2885   verify_numa_regions("GC Start");
2886 }
2887 
2888 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2889   if (VerifyRememberedSets) {
2890     log_info(gc, verify)("[Verifying RemSets after GC]");
2891     VerifyRegionRemSetClosure v_cl;
2892     heap_region_iterate(&v_cl);
2893   }
2894   _verifier->verify_after_gc(type);
2895   _verifier->check_bitmaps("GC End");
2896   verify_numa_regions("GC End");
2897 }
2898 
2899 void G1CollectedHeap::expand_heap_after_young_collection(){
2900   size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2901   if (expand_bytes > 0) {
2902     // No need for an ergo logging here,
2903     // expansion_amount() does this when it returns a value > 0.
2904     double expand_ms;
2905     if (!expand(expand_bytes, _workers, &expand_ms)) {
2906       // We failed to expand the heap. Cannot do anything about it.
2907     }
2908     phase_times()->record_expand_heap_time(expand_ms);
2909   }
2910 }
2911 
2912 const char* G1CollectedHeap::young_gc_name() const {
2913   if (collector_state()->in_concurrent_start_gc()) {
2914     return "Pause Young (Concurrent Start)";
2915   } else if (collector_state()->in_young_only_phase()) {
2916     if (collector_state()->in_young_gc_before_mixed()) {
2917       return "Pause Young (Prepare Mixed)";
2918     } else {
2919       return "Pause Young (Normal)";
2920     }
2921   } else {
2922     return "Pause Young (Mixed)";
2923   }
2924 }
2925 
2926 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2927   assert_at_safepoint_on_vm_thread();
2928   guarantee(!is_gc_active(), "collection is not reentrant");
2929 
2930   if (GCLocker::check_active_before_gc()) {
2931     return false;
2932   }
2933 
2934   do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2935   if (should_upgrade_to_full_gc(gc_cause())) {
2936     log_info(gc, ergo)("Attempting maximally compacting collection");
2937     bool result = do_full_collection(false /* explicit gc */,
2938                                      true /* clear_all_soft_refs */);
2939     // do_full_collection only fails if blocked by GC locker, but
2940     // we've already checked for that above.
2941     assert(result, "invariant");
2942   }
2943   return true;
2944 }
2945 
2946 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2947   GCIdMark gc_id_mark;
2948 
2949   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2950   ResourceMark rm;
2951 
2952   policy()->note_gc_start();
2953 
2954   _gc_timer_stw->register_gc_start();
2955   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2956 
2957   wait_for_root_region_scanning();
2958 
2959   print_heap_before_gc();
2960   print_heap_regions();
2961   trace_heap_before_gc(_gc_tracer_stw);
2962 
2963   _verifier->verify_region_sets_optional();
2964   _verifier->verify_dirty_young_regions();
2965 
2966   // We should not be doing concurrent start unless the concurrent mark thread is running
2967   if (!_cm_thread->should_terminate()) {
2968     // This call will decide whether this pause is a concurrent start
2969     // pause. If it is, in_concurrent_start_gc() will return true
2970     // for the duration of this pause.
2971     policy()->decide_on_conc_mark_initiation();
2972   }
2973 
2974   // We do not allow concurrent start to be piggy-backed on a mixed GC.
2975   assert(!collector_state()->in_concurrent_start_gc() ||
2976          collector_state()->in_young_only_phase(), "sanity");
2977   // We also do not allow mixed GCs during marking.
2978   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2979 
2980   // Record whether this pause is a concurrent start. When the current
2981   // thread has completed its logging output and it's safe to signal
2982   // the CM thread, the flag's value in the policy has been reset.
2983   bool should_start_conc_mark = collector_state()->in_concurrent_start_gc();
2984   if (should_start_conc_mark) {
2985     _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2986   }
2987 
2988   // Inner scope for scope based logging, timers, and stats collection
2989   {
2990     G1EvacuationInfo evacuation_info;
2991 
2992     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2993 
2994     GCTraceCPUTime tcpu;
2995 
2996     GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
2997 
2998     uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
2999                                                             workers()->active_workers(),
3000                                                             Threads::number_of_non_daemon_threads());
3001     active_workers = workers()->update_active_workers(active_workers);
3002     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3003 
3004     G1MonitoringScope ms(g1mm(),
3005                          false /* full_gc */,
3006                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3007 
3008     G1HeapTransition heap_transition(this);
3009 
3010     {
3011       IsGCActiveMark x;
3012 
3013       gc_prologue(false);
3014 
3015       G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3016       verify_before_young_collection(verify_type);
3017 
3018       {
3019         // The elapsed time induced by the start time below deliberately elides
3020         // the possible verification above.
3021         double sample_start_time_sec = os::elapsedTime();
3022 
3023         // Please see comment in g1CollectedHeap.hpp and
3024         // G1CollectedHeap::ref_processing_init() to see how
3025         // reference processing currently works in G1.
3026         _ref_processor_stw->enable_discovery();
3027 
3028         // We want to temporarily turn off discovery by the
3029         // CM ref processor, if necessary, and turn it back on
3030         // on again later if we do. Using a scoped
3031         // NoRefDiscovery object will do this.
3032         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3033 
3034         policy()->record_collection_pause_start(sample_start_time_sec);
3035 
3036         // Forget the current allocation region (we might even choose it to be part
3037         // of the collection set!).
3038         _allocator->release_mutator_alloc_regions();
3039 
3040         calculate_collection_set(evacuation_info, target_pause_time_ms);
3041 
3042         G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3043         G1ParScanThreadStateSet per_thread_states(this,
3044                                                   &rdcqs,
3045                                                   workers()->active_workers(),
3046                                                   collection_set()->young_region_length(),
3047                                                   collection_set()->optional_region_length());
3048         pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3049 
3050         // Actually do the work...
3051         evacuate_initial_collection_set(&per_thread_states);
3052 
3053         if (_collection_set.optional_region_length() != 0) {
3054           evacuate_optional_collection_set(&per_thread_states);
3055         }
3056         post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3057 
3058         start_new_collection_set();
3059 
3060         _survivor_evac_stats.adjust_desired_plab_sz();
3061         _old_evac_stats.adjust_desired_plab_sz();
3062 
3063         if (should_start_conc_mark) {
3064           // We have to do this before we notify the CM threads that
3065           // they can start working to make sure that all the
3066           // appropriate initialization is done on the CM object.
3067           concurrent_mark()->post_concurrent_start();
3068           // Note that we don't actually trigger the CM thread at
3069           // this point. We do that later when we're sure that
3070           // the current thread has completed its logging output.
3071         }
3072 
3073         allocate_dummy_regions();
3074 
3075         _allocator->init_mutator_alloc_regions();
3076 
3077         expand_heap_after_young_collection();
3078 
3079         double sample_end_time_sec = os::elapsedTime();
3080         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3081         policy()->record_collection_pause_end(pause_time_ms);
3082       }
3083 
3084       verify_after_young_collection(verify_type);
3085 
3086       gc_epilogue(false);
3087     }
3088 
3089     // Print the remainder of the GC log output.
3090     if (evacuation_failed()) {
3091       log_info(gc)("To-space exhausted");
3092     }
3093 
3094     policy()->print_phases();
3095     heap_transition.print();
3096 
3097     _hrm->verify_optional();
3098     _verifier->verify_region_sets_optional();
3099 
3100     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3101     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3102 
3103     print_heap_after_gc();
3104     print_heap_regions();
3105     trace_heap_after_gc(_gc_tracer_stw);
3106 
3107     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3108     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3109     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3110     // before any GC notifications are raised.
3111     g1mm()->update_sizes();
3112 
3113     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3114     _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3115     _gc_timer_stw->register_gc_end();
3116     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3117   }
3118   // It should now be safe to tell the concurrent mark thread to start
3119   // without its logging output interfering with the logging output
3120   // that came from the pause.
3121 
3122   if (should_start_conc_mark) {
3123     // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3124     // thread(s) could be running concurrently with us. Make sure that anything
3125     // after this point does not assume that we are the only GC thread running.
3126     // Note: of course, the actual marking work will not start until the safepoint
3127     // itself is released in SuspendibleThreadSet::desynchronize().
3128     do_concurrent_mark();
3129     ConcurrentGCBreakpoints::notify_idle_to_active();
3130   }
3131 }
3132 
3133 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3134   G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3135   workers()->run_task(&rsfp_task);
3136 }
3137 
3138 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3139   double remove_self_forwards_start = os::elapsedTime();
3140 
3141   remove_self_forwarding_pointers(rdcqs);
3142   _preserved_marks_set.restore(workers());
3143 
3144   phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3145 }
3146 
3147 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3148   if (!_evacuation_failed) {
3149     _evacuation_failed = true;
3150   }
3151 
3152   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3153   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3154 }
3155 
3156 bool G1ParEvacuateFollowersClosure::offer_termination() {
3157   EventGCPhaseParallel event;
3158   G1ParScanThreadState* const pss = par_scan_state();
3159   start_term_time();
3160   const bool res = terminator()->offer_termination();
3161   end_term_time();
3162   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3163   return res;
3164 }
3165 
3166 void G1ParEvacuateFollowersClosure::do_void() {
3167   EventGCPhaseParallel event;
3168   G1ParScanThreadState* const pss = par_scan_state();
3169   pss->trim_queue();
3170   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3171   do {
3172     EventGCPhaseParallel event;
3173     pss->steal_and_trim_queue(queues());
3174     event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3175   } while (!offer_termination());
3176 }
3177 
3178 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3179                                         bool class_unloading_occurred) {
3180   uint num_workers = workers()->active_workers();
3181   G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3182   workers()->run_task(&unlink_task);
3183 }
3184 
3185 // Clean string dedup data structures.
3186 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3187 // record the durations of the phases. Hence the almost-copy.
3188 class G1StringDedupCleaningTask : public AbstractGangTask {
3189   BoolObjectClosure* _is_alive;
3190   OopClosure* _keep_alive;
3191   G1GCPhaseTimes* _phase_times;
3192 
3193 public:
3194   G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3195                             OopClosure* keep_alive,
3196                             G1GCPhaseTimes* phase_times) :
3197     AbstractGangTask("Partial Cleaning Task"),
3198     _is_alive(is_alive),
3199     _keep_alive(keep_alive),
3200     _phase_times(phase_times)
3201   {
3202     assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3203     StringDedup::gc_prologue(true);
3204   }
3205 
3206   ~G1StringDedupCleaningTask() {
3207     StringDedup::gc_epilogue();
3208   }
3209 
3210   void work(uint worker_id) {
3211     StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3212     {
3213       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3214       StringDedupQueue::unlink_or_oops_do(&cl);
3215     }
3216     {
3217       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3218       StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3219     }
3220   }
3221 };
3222 
3223 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3224                                             OopClosure* keep_alive,
3225                                             G1GCPhaseTimes* phase_times) {
3226   G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3227   workers()->run_task(&cl);
3228 }
3229 
3230 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3231  private:
3232   G1RedirtyCardsQueueSet* _qset;
3233   G1CollectedHeap* _g1h;
3234   BufferNode* volatile _nodes;
3235 
3236   void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3237     size_t buffer_size = _qset->buffer_size();
3238     BufferNode* next = Atomic::load(&_nodes);
3239     while (next != NULL) {
3240       BufferNode* node = next;
3241       next = Atomic::cmpxchg(&_nodes, node, node->next());
3242       if (next == node) {
3243         cl->apply_to_buffer(node, buffer_size, worker_id);
3244         next = node->next();
3245       }
3246     }
3247   }
3248 
3249  public:
3250   G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3251     AbstractGangTask("Redirty Cards"),
3252     _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3253 
3254   virtual void work(uint worker_id) {
3255     G1GCPhaseTimes* p = _g1h->phase_times();
3256     G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3257 
3258     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3259     par_apply(&cl, worker_id);
3260 
3261     p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3262   }
3263 };
3264 
3265 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3266   double redirty_logged_cards_start = os::elapsedTime();
3267 
3268   G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3269   workers()->run_task(&redirty_task);
3270 
3271   G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3272   dcq.merge_bufferlists(rdcqs);
3273 
3274   phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3275 }
3276 
3277 // Weak Reference Processing support
3278 
3279 bool G1STWIsAliveClosure::do_object_b(oop p) {
3280   // An object is reachable if it is outside the collection set,
3281   // or is inside and copied.
3282   return !_g1h->is_in_cset(p) || p->is_forwarded();
3283 }
3284 
3285 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3286   assert(obj != NULL, "must not be NULL");
3287   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3288   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3289   // may falsely indicate that this is not the case here: however the collection set only
3290   // contains old regions when concurrent mark is not running.
3291   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3292 }
3293 
3294 // Non Copying Keep Alive closure
3295 class G1KeepAliveClosure: public OopClosure {
3296   G1CollectedHeap*_g1h;
3297 public:
3298   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3299   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3300   void do_oop(oop* p) {
3301     oop obj = *p;
3302     assert(obj != NULL, "the caller should have filtered out NULL values");
3303 
3304     const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3305     if (!region_attr.is_in_cset_or_humongous()) {
3306       return;
3307     }
3308     if (region_attr.is_in_cset()) {
3309       assert( obj->is_forwarded(), "invariant" );
3310       *p = obj->forwardee();
3311     } else {
3312       assert(!obj->is_forwarded(), "invariant" );
3313       assert(region_attr.is_humongous(),
3314              "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3315      _g1h->set_humongous_is_live(obj);
3316     }
3317   }
3318 };
3319 
3320 // Copying Keep Alive closure - can be called from both
3321 // serial and parallel code as long as different worker
3322 // threads utilize different G1ParScanThreadState instances
3323 // and different queues.
3324 
3325 class G1CopyingKeepAliveClosure: public OopClosure {
3326   G1CollectedHeap*         _g1h;
3327   G1ParScanThreadState*    _par_scan_state;
3328 
3329 public:
3330   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3331                             G1ParScanThreadState* pss):
3332     _g1h(g1h),
3333     _par_scan_state(pss)
3334   {}
3335 
3336   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3337   virtual void do_oop(      oop* p) { do_oop_work(p); }
3338 
3339   template <class T> void do_oop_work(T* p) {
3340     oop obj = RawAccess<>::oop_load(p);
3341 
3342     if (_g1h->is_in_cset_or_humongous(obj)) {
3343       // If the referent object has been forwarded (either copied
3344       // to a new location or to itself in the event of an
3345       // evacuation failure) then we need to update the reference
3346       // field and, if both reference and referent are in the G1
3347       // heap, update the RSet for the referent.
3348       //
3349       // If the referent has not been forwarded then we have to keep
3350       // it alive by policy. Therefore we have copy the referent.
3351       //
3352       // When the queue is drained (after each phase of reference processing)
3353       // the object and it's followers will be copied, the reference field set
3354       // to point to the new location, and the RSet updated.
3355       _par_scan_state->push_on_queue(ScannerTask(p));
3356     }
3357   }
3358 };
3359 
3360 // Serial drain queue closure. Called as the 'complete_gc'
3361 // closure for each discovered list in some of the
3362 // reference processing phases.
3363 
3364 class G1STWDrainQueueClosure: public VoidClosure {
3365 protected:
3366   G1CollectedHeap* _g1h;
3367   G1ParScanThreadState* _par_scan_state;
3368 
3369   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3370 
3371 public:
3372   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3373     _g1h(g1h),
3374     _par_scan_state(pss)
3375   { }
3376 
3377   void do_void() {
3378     G1ParScanThreadState* const pss = par_scan_state();
3379     pss->trim_queue();
3380   }
3381 };
3382 
3383 // Parallel Reference Processing closures
3384 
3385 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3386 // processing during G1 evacuation pauses.
3387 
3388 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3389 private:
3390   G1CollectedHeap*          _g1h;
3391   G1ParScanThreadStateSet*  _pss;
3392   G1ScannerTasksQueueSet*   _queues;
3393   WorkGang*                 _workers;
3394 
3395 public:
3396   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3397                            G1ParScanThreadStateSet* per_thread_states,
3398                            WorkGang* workers,
3399                            G1ScannerTasksQueueSet *task_queues) :
3400     _g1h(g1h),
3401     _pss(per_thread_states),
3402     _queues(task_queues),
3403     _workers(workers)
3404   {
3405     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3406   }
3407 
3408   // Executes the given task using concurrent marking worker threads.
3409   virtual void execute(ProcessTask& task, uint ergo_workers);
3410 };
3411 
3412 // Gang task for possibly parallel reference processing
3413 
3414 class G1STWRefProcTaskProxy: public AbstractGangTask {
3415   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3416   ProcessTask&     _proc_task;
3417   G1CollectedHeap* _g1h;
3418   G1ParScanThreadStateSet* _pss;
3419   G1ScannerTasksQueueSet* _task_queues;
3420   TaskTerminator* _terminator;
3421 
3422 public:
3423   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3424                         G1CollectedHeap* g1h,
3425                         G1ParScanThreadStateSet* per_thread_states,
3426                         G1ScannerTasksQueueSet *task_queues,
3427                         TaskTerminator* terminator) :
3428     AbstractGangTask("Process reference objects in parallel"),
3429     _proc_task(proc_task),
3430     _g1h(g1h),
3431     _pss(per_thread_states),
3432     _task_queues(task_queues),
3433     _terminator(terminator)
3434   {}
3435 
3436   virtual void work(uint worker_id) {
3437     // The reference processing task executed by a single worker.
3438     ResourceMark rm;
3439 
3440     G1STWIsAliveClosure is_alive(_g1h);
3441 
3442     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3443     pss->set_ref_discoverer(NULL);
3444 
3445     // Keep alive closure.
3446     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3447 
3448     // Complete GC closure
3449     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3450 
3451     // Call the reference processing task's work routine.
3452     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3453 
3454     // Note we cannot assert that the refs array is empty here as not all
3455     // of the processing tasks (specifically phase2 - pp2_work) execute
3456     // the complete_gc closure (which ordinarily would drain the queue) so
3457     // the queue may not be empty.
3458   }
3459 };
3460 
3461 // Driver routine for parallel reference processing.
3462 // Creates an instance of the ref processing gang
3463 // task and has the worker threads execute it.
3464 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3465   assert(_workers != NULL, "Need parallel worker threads.");
3466 
3467   assert(_workers->active_workers() >= ergo_workers,
3468          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3469          ergo_workers, _workers->active_workers());
3470   TaskTerminator terminator(ergo_workers, _queues);
3471   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3472 
3473   _workers->run_task(&proc_task_proxy, ergo_workers);
3474 }
3475 
3476 // End of weak reference support closures
3477 
3478 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3479   double ref_proc_start = os::elapsedTime();
3480 
3481   ReferenceProcessor* rp = _ref_processor_stw;
3482   assert(rp->discovery_enabled(), "should have been enabled");
3483 
3484   // Closure to test whether a referent is alive.
3485   G1STWIsAliveClosure is_alive(this);
3486 
3487   // Even when parallel reference processing is enabled, the processing
3488   // of JNI refs is serial and performed serially by the current thread
3489   // rather than by a worker. The following PSS will be used for processing
3490   // JNI refs.
3491 
3492   // Use only a single queue for this PSS.
3493   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3494   pss->set_ref_discoverer(NULL);
3495   assert(pss->queue_is_empty(), "pre-condition");
3496 
3497   // Keep alive closure.
3498   G1CopyingKeepAliveClosure keep_alive(this, pss);
3499 
3500   // Serial Complete GC closure
3501   G1STWDrainQueueClosure drain_queue(this, pss);
3502 
3503   // Setup the soft refs policy...
3504   rp->setup_policy(false);
3505 
3506   ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3507 
3508   ReferenceProcessorStats stats;
3509   if (!rp->processing_is_mt()) {
3510     // Serial reference processing...
3511     stats = rp->process_discovered_references(&is_alive,
3512                                               &keep_alive,
3513                                               &drain_queue,
3514                                               NULL,
3515                                               pt);
3516   } else {
3517     uint no_of_gc_workers = workers()->active_workers();
3518 
3519     // Parallel reference processing
3520     assert(no_of_gc_workers <= rp->max_num_queues(),
3521            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3522            no_of_gc_workers,  rp->max_num_queues());
3523 
3524     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3525     stats = rp->process_discovered_references(&is_alive,
3526                                               &keep_alive,
3527                                               &drain_queue,
3528                                               &par_task_executor,
3529                                               pt);
3530   }
3531 
3532   _gc_tracer_stw->report_gc_reference_stats(stats);
3533 
3534   // We have completed copying any necessary live referent objects.
3535   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3536 
3537   make_pending_list_reachable();
3538 
3539   assert(!rp->discovery_enabled(), "Postcondition");
3540   rp->verify_no_references_recorded();
3541 
3542   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3543   phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3544 }
3545 
3546 void G1CollectedHeap::make_pending_list_reachable() {
3547   if (collector_state()->in_concurrent_start_gc()) {
3548     oop pll_head = Universe::reference_pending_list();
3549     if (pll_head != NULL) {
3550       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3551       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3552     }
3553   }
3554 }
3555 
3556 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3557   Ticks start = Ticks::now();
3558   per_thread_states->flush();
3559   phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3560 }
3561 
3562 class G1PrepareEvacuationTask : public AbstractGangTask {
3563   class G1PrepareRegionsClosure : public HeapRegionClosure {
3564     G1CollectedHeap* _g1h;
3565     G1PrepareEvacuationTask* _parent_task;
3566     size_t _worker_humongous_total;
3567     size_t _worker_humongous_candidates;
3568 
3569     bool humongous_region_is_candidate(HeapRegion* region) const {
3570       assert(region->is_starts_humongous(), "Must start a humongous object");
3571 
3572       oop obj = oop(region->bottom());
3573 
3574       // Dead objects cannot be eager reclaim candidates. Due to class
3575       // unloading it is unsafe to query their classes so we return early.
3576       if (_g1h->is_obj_dead(obj, region)) {
3577         return false;
3578       }
3579 
3580       // If we do not have a complete remembered set for the region, then we can
3581       // not be sure that we have all references to it.
3582       if (!region->rem_set()->is_complete()) {
3583         return false;
3584       }
3585       // Candidate selection must satisfy the following constraints
3586       // while concurrent marking is in progress:
3587       //
3588       // * In order to maintain SATB invariants, an object must not be
3589       // reclaimed if it was allocated before the start of marking and
3590       // has not had its references scanned.  Such an object must have
3591       // its references (including type metadata) scanned to ensure no
3592       // live objects are missed by the marking process.  Objects
3593       // allocated after the start of concurrent marking don't need to
3594       // be scanned.
3595       //
3596       // * An object must not be reclaimed if it is on the concurrent
3597       // mark stack.  Objects allocated after the start of concurrent
3598       // marking are never pushed on the mark stack.
3599       //
3600       // Nominating only objects allocated after the start of concurrent
3601       // marking is sufficient to meet both constraints.  This may miss
3602       // some objects that satisfy the constraints, but the marking data
3603       // structures don't support efficiently performing the needed
3604       // additional tests or scrubbing of the mark stack.
3605       //
3606       // However, we presently only nominate is_typeArray() objects.
3607       // A humongous object containing references induces remembered
3608       // set entries on other regions.  In order to reclaim such an
3609       // object, those remembered sets would need to be cleaned up.
3610       //
3611       // We also treat is_typeArray() objects specially, allowing them
3612       // to be reclaimed even if allocated before the start of
3613       // concurrent mark.  For this we rely on mark stack insertion to
3614       // exclude is_typeArray() objects, preventing reclaiming an object
3615       // that is in the mark stack.  We also rely on the metadata for
3616       // such objects to be built-in and so ensured to be kept live.
3617       // Frequent allocation and drop of large binary blobs is an
3618       // important use case for eager reclaim, and this special handling
3619       // may reduce needed headroom.
3620 
3621       return obj->is_typeArray() &&
3622              _g1h->is_potential_eager_reclaim_candidate(region);
3623     }
3624 
3625   public:
3626     G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3627       _g1h(g1h),
3628       _parent_task(parent_task),
3629       _worker_humongous_total(0),
3630       _worker_humongous_candidates(0) { }
3631 
3632     ~G1PrepareRegionsClosure() {
3633       _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3634       _parent_task->add_humongous_total(_worker_humongous_total);
3635     }
3636 
3637     virtual bool do_heap_region(HeapRegion* hr) {
3638       // First prepare the region for scanning
3639       _g1h->rem_set()->prepare_region_for_scan(hr);
3640 
3641       // Now check if region is a humongous candidate
3642       if (!hr->is_starts_humongous()) {
3643         _g1h->register_region_with_region_attr(hr);
3644         return false;
3645       }
3646 
3647       uint index = hr->hrm_index();
3648       if (humongous_region_is_candidate(hr)) {
3649         _g1h->set_humongous_reclaim_candidate(index, true);
3650         _g1h->register_humongous_region_with_region_attr(index);
3651         _worker_humongous_candidates++;
3652         // We will later handle the remembered sets of these regions.
3653       } else {
3654         _g1h->set_humongous_reclaim_candidate(index, false);
3655         _g1h->register_region_with_region_attr(hr);
3656       }
3657       _worker_humongous_total++;
3658 
3659       return false;
3660     }
3661   };
3662 
3663   G1CollectedHeap* _g1h;
3664   HeapRegionClaimer _claimer;
3665   volatile size_t _humongous_total;
3666   volatile size_t _humongous_candidates;
3667 public:
3668   G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3669     AbstractGangTask("Prepare Evacuation"),
3670     _g1h(g1h),
3671     _claimer(_g1h->workers()->active_workers()),
3672     _humongous_total(0),
3673     _humongous_candidates(0) { }
3674 
3675   ~G1PrepareEvacuationTask() {
3676     _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3677   }
3678 
3679   void work(uint worker_id) {
3680     G1PrepareRegionsClosure cl(_g1h, this);
3681     _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3682   }
3683 
3684   void add_humongous_candidates(size_t candidates) {
3685     Atomic::add(&_humongous_candidates, candidates);
3686   }
3687 
3688   void add_humongous_total(size_t total) {
3689     Atomic::add(&_humongous_total, total);
3690   }
3691 
3692   size_t humongous_candidates() {
3693     return _humongous_candidates;
3694   }
3695 
3696   size_t humongous_total() {
3697     return _humongous_total;
3698   }
3699 };
3700 
3701 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3702   _bytes_used_during_gc = 0;
3703 
3704   _expand_heap_after_alloc_failure = true;
3705   _evacuation_failed = false;
3706 
3707   // Disable the hot card cache.
3708   _hot_card_cache->reset_hot_cache_claimed_index();
3709   _hot_card_cache->set_use_cache(false);
3710 
3711   // Initialize the GC alloc regions.
3712   _allocator->init_gc_alloc_regions(evacuation_info);
3713 
3714   {
3715     Ticks start = Ticks::now();
3716     rem_set()->prepare_for_scan_heap_roots();
3717     phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3718   }
3719 
3720   {
3721     G1PrepareEvacuationTask g1_prep_task(this);
3722     Tickspan task_time = run_task_timed(&g1_prep_task);
3723 
3724     phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3725                                            g1_prep_task.humongous_total(),
3726                                            g1_prep_task.humongous_candidates());
3727   }
3728 
3729   assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3730   _preserved_marks_set.assert_empty();
3731 
3732 #if COMPILER2_OR_JVMCI
3733   DerivedPointerTable::clear();
3734 #endif
3735 
3736   // Concurrent start needs claim bits to keep track of the marked-through CLDs.
3737   if (collector_state()->in_concurrent_start_gc()) {
3738     concurrent_mark()->pre_concurrent_start();
3739 
3740     double start_clear_claimed_marks = os::elapsedTime();
3741 
3742     ClassLoaderDataGraph::clear_claimed_marks();
3743 
3744     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3745     phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3746   }
3747 
3748   // Should G1EvacuationFailureALot be in effect for this GC?
3749   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3750 }
3751 
3752 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3753 protected:
3754   G1CollectedHeap* _g1h;
3755   G1ParScanThreadStateSet* _per_thread_states;
3756   G1ScannerTasksQueueSet* _task_queues;
3757   TaskTerminator _terminator;
3758   uint _num_workers;
3759 
3760   void evacuate_live_objects(G1ParScanThreadState* pss,
3761                              uint worker_id,
3762                              G1GCPhaseTimes::GCParPhases objcopy_phase,
3763                              G1GCPhaseTimes::GCParPhases termination_phase) {
3764     G1GCPhaseTimes* p = _g1h->phase_times();
3765 
3766     Ticks start = Ticks::now();
3767     G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3768     cl.do_void();
3769 
3770     assert(pss->queue_is_empty(), "should be empty");
3771 
3772     Tickspan evac_time = (Ticks::now() - start);
3773     p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3774 
3775     if (termination_phase == G1GCPhaseTimes::Termination) {
3776       p->record_time_secs(termination_phase, worker_id, cl.term_time());
3777       p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3778     } else {
3779       p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3780       p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3781     }
3782     assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3783   }
3784 
3785   virtual void start_work(uint worker_id) { }
3786 
3787   virtual void end_work(uint worker_id) { }
3788 
3789   virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3790 
3791   virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3792 
3793 public:
3794   G1EvacuateRegionsBaseTask(const char* name,
3795                             G1ParScanThreadStateSet* per_thread_states,
3796                             G1ScannerTasksQueueSet* task_queues,
3797                             uint num_workers) :
3798     AbstractGangTask(name),
3799     _g1h(G1CollectedHeap::heap()),
3800     _per_thread_states(per_thread_states),
3801     _task_queues(task_queues),
3802     _terminator(num_workers, _task_queues),
3803     _num_workers(num_workers)
3804   { }
3805 
3806   void work(uint worker_id) {
3807     start_work(worker_id);
3808 
3809     {
3810       ResourceMark rm;
3811 
3812       G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3813       pss->set_ref_discoverer(_g1h->ref_processor_stw());
3814 
3815       scan_roots(pss, worker_id);
3816       evacuate_live_objects(pss, worker_id);
3817     }
3818 
3819     end_work(worker_id);
3820   }
3821 };
3822 
3823 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3824   G1RootProcessor* _root_processor;
3825 
3826   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3827     _root_processor->evacuate_roots(pss, worker_id);
3828     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3829     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3830   }
3831 
3832   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3833     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3834   }
3835 
3836   void start_work(uint worker_id) {
3837     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3838   }
3839 
3840   void end_work(uint worker_id) {
3841     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3842   }
3843 
3844 public:
3845   G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3846                         G1ParScanThreadStateSet* per_thread_states,
3847                         G1ScannerTasksQueueSet* task_queues,
3848                         G1RootProcessor* root_processor,
3849                         uint num_workers) :
3850     G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3851     _root_processor(root_processor)
3852   { }
3853 };
3854 
3855 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3856   G1GCPhaseTimes* p = phase_times();
3857 
3858   {
3859     Ticks start = Ticks::now();
3860     rem_set()->merge_heap_roots(true /* initial_evacuation */);
3861     p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3862   }
3863 
3864   Tickspan task_time;
3865   const uint num_workers = workers()->active_workers();
3866 
3867   Ticks start_processing = Ticks::now();
3868   {
3869     G1RootProcessor root_processor(this, num_workers);
3870     G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3871     task_time = run_task_timed(&g1_par_task);
3872     // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3873     // To extract its code root fixup time we measure total time of this scope and
3874     // subtract from the time the WorkGang task took.
3875   }
3876   Tickspan total_processing = Ticks::now() - start_processing;
3877 
3878   p->record_initial_evac_time(task_time.seconds() * 1000.0);
3879   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3880 }
3881 
3882 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3883 
3884   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3885     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3886     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3887   }
3888 
3889   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3890     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3891   }
3892 
3893 public:
3894   G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3895                                 G1ScannerTasksQueueSet* queues,
3896                                 uint num_workers) :
3897     G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3898   }
3899 };
3900 
3901 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3902   class G1MarkScope : public MarkScope { };
3903 
3904   Tickspan task_time;
3905 
3906   Ticks start_processing = Ticks::now();
3907   {
3908     G1MarkScope code_mark_scope;
3909     G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3910     task_time = run_task_timed(&task);
3911     // See comment in evacuate_collection_set() for the reason of the scope.
3912   }
3913   Tickspan total_processing = Ticks::now() - start_processing;
3914 
3915   G1GCPhaseTimes* p = phase_times();
3916   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3917 }
3918 
3919 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3920   const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3921 
3922   while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3923 
3924     double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3925     double time_left_ms = MaxGCPauseMillis - time_used_ms;
3926 
3927     if (time_left_ms < 0 ||
3928         !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3929       log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3930                                 _collection_set.optional_region_length(), time_left_ms);
3931       break;
3932     }
3933 
3934     {
3935       Ticks start = Ticks::now();
3936       rem_set()->merge_heap_roots(false /* initial_evacuation */);
3937       phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3938     }
3939 
3940     {
3941       Ticks start = Ticks::now();
3942       evacuate_next_optional_regions(per_thread_states);
3943       phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3944     }
3945   }
3946 
3947   _collection_set.abandon_optional_collection_set(per_thread_states);
3948 }
3949 
3950 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3951                                                    G1RedirtyCardsQueueSet* rdcqs,
3952                                                    G1ParScanThreadStateSet* per_thread_states) {
3953   G1GCPhaseTimes* p = phase_times();
3954 
3955   rem_set()->cleanup_after_scan_heap_roots();
3956 
3957   // Process any discovered reference objects - we have
3958   // to do this _before_ we retire the GC alloc regions
3959   // as we may have to copy some 'reachable' referent
3960   // objects (and their reachable sub-graphs) that were
3961   // not copied during the pause.
3962   process_discovered_references(per_thread_states);
3963 
3964   G1STWIsAliveClosure is_alive(this);
3965   G1KeepAliveClosure keep_alive(this);
3966 
3967   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
3968 
3969   if (G1StringDedup::is_enabled()) {
3970     double string_dedup_time_ms = os::elapsedTime();
3971 
3972     string_dedup_cleaning(&is_alive, &keep_alive, p);
3973 
3974     double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3975     p->record_string_deduplication_time(string_cleanup_time_ms);
3976   }
3977 
3978   _allocator->release_gc_alloc_regions(evacuation_info);
3979 
3980   if (evacuation_failed()) {
3981     restore_after_evac_failure(rdcqs);
3982 
3983     // Reset the G1EvacuationFailureALot counters and flags
3984     NOT_PRODUCT(reset_evacuation_should_fail();)
3985 
3986     double recalculate_used_start = os::elapsedTime();
3987     set_used(recalculate_used());
3988     p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3989 
3990     if (_archive_allocator != NULL) {
3991       _archive_allocator->clear_used();
3992     }
3993     for (uint i = 0; i < ParallelGCThreads; i++) {
3994       if (_evacuation_failed_info_array[i].has_failed()) {
3995         _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3996       }
3997     }
3998   } else {
3999     // The "used" of the the collection set have already been subtracted
4000     // when they were freed.  Add in the bytes used.
4001     increase_used(_bytes_used_during_gc);
4002   }
4003 
4004   _preserved_marks_set.assert_empty();
4005 
4006   merge_per_thread_state_info(per_thread_states);
4007 
4008   // Reset and re-enable the hot card cache.
4009   // Note the counts for the cards in the regions in the
4010   // collection set are reset when the collection set is freed.
4011   _hot_card_cache->reset_hot_cache();
4012   _hot_card_cache->set_use_cache(true);
4013 
4014   purge_code_root_memory();
4015 
4016   redirty_logged_cards(rdcqs);
4017 
4018   free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4019 
4020   eagerly_reclaim_humongous_regions();
4021 
4022   record_obj_copy_mem_stats();
4023 
4024   evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4025   evacuation_info.set_bytes_used(_bytes_used_during_gc);
4026 
4027 #if COMPILER2_OR_JVMCI
4028   double start = os::elapsedTime();
4029   DerivedPointerTable::update_pointers();
4030   phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4031 #endif
4032   policy()->print_age_table();
4033 }
4034 
4035 void G1CollectedHeap::record_obj_copy_mem_stats() {
4036   policy()->old_gen_alloc_tracker()->
4037     add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4038 
4039   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4040                                                create_g1_evac_summary(&_old_evac_stats));
4041 }
4042 
4043 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4044   assert(!hr->is_free(), "the region should not be free");
4045   assert(!hr->is_empty(), "the region should not be empty");
4046   assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4047 
4048   if (G1VerifyBitmaps) {
4049     MemRegion mr(hr->bottom(), hr->end());
4050     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4051   }
4052 
4053   // Clear the card counts for this region.
4054   // Note: we only need to do this if the region is not young
4055   // (since we don't refine cards in young regions).
4056   if (!hr->is_young()) {
4057     _hot_card_cache->reset_card_counts(hr);
4058   }
4059 
4060   // Reset region metadata to allow reuse.
4061   hr->hr_clear(true /* clear_space */);
4062   _policy->remset_tracker()->update_at_free(hr);
4063 
4064   if (free_list != NULL) {
4065     free_list->add_ordered(hr);
4066   }
4067 }
4068 
4069 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4070                                             FreeRegionList* free_list) {
4071   assert(hr->is_humongous(), "this is only for humongous regions");
4072   assert(free_list != NULL, "pre-condition");
4073   hr->clear_humongous();
4074   free_region(hr, free_list);
4075 }
4076 
4077 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4078                                            const uint humongous_regions_removed) {
4079   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4080     MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4081     _old_set.bulk_remove(old_regions_removed);
4082     _humongous_set.bulk_remove(humongous_regions_removed);
4083   }
4084 
4085 }
4086 
4087 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4088   assert(list != NULL, "list can't be null");
4089   if (!list->is_empty()) {
4090     MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4091     _hrm->insert_list_into_free_list(list);
4092   }
4093 }
4094 
4095 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4096   decrease_used(bytes);
4097 }
4098 
4099 class G1FreeCollectionSetTask : public AbstractGangTask {
4100   // Helper class to keep statistics for the collection set freeing
4101   class FreeCSetStats {
4102     size_t _before_used_bytes;   // Usage in regions successfully evacutate
4103     size_t _after_used_bytes;    // Usage in regions failing evacuation
4104     size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4105     size_t _failure_used_words;  // Live size in failed regions
4106     size_t _failure_waste_words; // Wasted size in failed regions
4107     size_t _rs_length;           // Remembered set size
4108     uint _regions_freed;         // Number of regions freed
4109   public:
4110     FreeCSetStats() :
4111         _before_used_bytes(0),
4112         _after_used_bytes(0),
4113         _bytes_allocated_in_old_since_last_gc(0),
4114         _failure_used_words(0),
4115         _failure_waste_words(0),
4116         _rs_length(0),
4117         _regions_freed(0) { }
4118 
4119     void merge_stats(FreeCSetStats* other) {
4120       assert(other != NULL, "invariant");
4121       _before_used_bytes += other->_before_used_bytes;
4122       _after_used_bytes += other->_after_used_bytes;
4123       _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4124       _failure_used_words += other->_failure_used_words;
4125       _failure_waste_words += other->_failure_waste_words;
4126       _rs_length += other->_rs_length;
4127       _regions_freed += other->_regions_freed;
4128     }
4129 
4130     void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4131       evacuation_info->set_regions_freed(_regions_freed);
4132       evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4133 
4134       g1h->decrement_summary_bytes(_before_used_bytes);
4135       g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4136 
4137       G1Policy *policy = g1h->policy();
4138       policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4139       policy->record_rs_length(_rs_length);
4140       policy->cset_regions_freed();
4141     }
4142 
4143     void account_failed_region(HeapRegion* r) {
4144       size_t used_words = r->marked_bytes() / HeapWordSize;
4145       _failure_used_words += used_words;
4146       _failure_waste_words += HeapRegion::GrainWords - used_words;
4147       _after_used_bytes += r->used();
4148 
4149       // When moving a young gen region to old gen, we "allocate" that whole
4150       // region there. This is in addition to any already evacuated objects.
4151       // Notify the policy about that. Old gen regions do not cause an
4152       // additional allocation: both the objects still in the region and the
4153       // ones already moved are accounted for elsewhere.
4154       if (r->is_young()) {
4155         _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4156       }
4157     }
4158 
4159     void account_evacuated_region(HeapRegion* r) {
4160       _before_used_bytes += r->used();
4161       _regions_freed += 1;
4162     }
4163 
4164     void account_rs_length(HeapRegion* r) {
4165       _rs_length += r->rem_set()->occupied();
4166     }
4167   };
4168 
4169   // Closure applied to all regions in the collection set.
4170   class FreeCSetClosure : public HeapRegionClosure {
4171     // Helper to send JFR events for regions.
4172     class JFREventForRegion {
4173       EventGCPhaseParallel _event;
4174     public:
4175       JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4176         _event.set_gcId(GCId::current());
4177         _event.set_gcWorkerId(worker_id);
4178         if (region->is_young()) {
4179           _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4180         } else {
4181           _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4182         }
4183       }
4184 
4185       ~JFREventForRegion() {
4186         _event.commit();
4187       }
4188     };
4189 
4190     // Helper to do timing for region work.
4191     class TimerForRegion {
4192       Tickspan& _time;
4193       Ticks     _start_time;
4194     public:
4195       TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4196       ~TimerForRegion() {
4197         _time += Ticks::now() - _start_time;
4198       }
4199     };
4200 
4201     // FreeCSetClosure members
4202     G1CollectedHeap* _g1h;
4203     const size_t*    _surviving_young_words;
4204     uint             _worker_id;
4205     Tickspan         _young_time;
4206     Tickspan         _non_young_time;
4207     FreeCSetStats*   _stats;
4208 
4209     void assert_in_cset(HeapRegion* r) {
4210       assert(r->young_index_in_cset() != 0 &&
4211              (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4212              "Young index %u is wrong for region %u of type %s with %u young regions",
4213              r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4214     }
4215 
4216     void handle_evacuated_region(HeapRegion* r) {
4217       assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4218       stats()->account_evacuated_region(r);
4219 
4220       // Free the region and and its remembered set.
4221       _g1h->free_region(r, NULL);
4222     }
4223 
4224     void handle_failed_region(HeapRegion* r) {
4225       // Do some allocation statistics accounting. Regions that failed evacuation
4226       // are always made old, so there is no need to update anything in the young
4227       // gen statistics, but we need to update old gen statistics.
4228       stats()->account_failed_region(r);
4229 
4230       // Update the region state due to the failed evacuation.
4231       r->handle_evacuation_failure();
4232 
4233       // Add region to old set, need to hold lock.
4234       MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4235       _g1h->old_set_add(r);
4236     }
4237 
4238     Tickspan& timer_for_region(HeapRegion* r) {
4239       return r->is_young() ? _young_time : _non_young_time;
4240     }
4241 
4242     FreeCSetStats* stats() {
4243       return _stats;
4244     }
4245   public:
4246     FreeCSetClosure(const size_t* surviving_young_words,
4247                     uint worker_id,
4248                     FreeCSetStats* stats) :
4249         HeapRegionClosure(),
4250         _g1h(G1CollectedHeap::heap()),
4251         _surviving_young_words(surviving_young_words),
4252         _worker_id(worker_id),
4253         _young_time(),
4254         _non_young_time(),
4255         _stats(stats) { }
4256 
4257     virtual bool do_heap_region(HeapRegion* r) {
4258       assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4259       JFREventForRegion event(r, _worker_id);
4260       TimerForRegion timer(timer_for_region(r));
4261 
4262       _g1h->clear_region_attr(r);
4263       stats()->account_rs_length(r);
4264 
4265       if (r->is_young()) {
4266         assert_in_cset(r);
4267         r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4268       }
4269 
4270       if (r->evacuation_failed()) {
4271         handle_failed_region(r);
4272       } else {
4273         handle_evacuated_region(r);
4274       }
4275       assert(!_g1h->is_on_master_free_list(r), "sanity");
4276 
4277       return false;
4278     }
4279 
4280     void report_timing(Tickspan parallel_time) {
4281       G1GCPhaseTimes* pt = _g1h->phase_times();
4282       pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4283       if (_young_time.value() > 0) {
4284         pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4285       }
4286       if (_non_young_time.value() > 0) {
4287         pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4288       }
4289     }
4290   };
4291 
4292   // G1FreeCollectionSetTask members
4293   G1CollectedHeap*  _g1h;
4294   G1EvacuationInfo* _evacuation_info;
4295   FreeCSetStats*    _worker_stats;
4296   HeapRegionClaimer _claimer;
4297   const size_t*     _surviving_young_words;
4298   uint              _active_workers;
4299 
4300   FreeCSetStats* worker_stats(uint worker) {
4301     return &_worker_stats[worker];
4302   }
4303 
4304   void report_statistics() {
4305     // Merge the accounting
4306     FreeCSetStats total_stats;
4307     for (uint worker = 0; worker < _active_workers; worker++) {
4308       total_stats.merge_stats(worker_stats(worker));
4309     }
4310     total_stats.report(_g1h, _evacuation_info);
4311   }
4312 
4313 public:
4314   G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4315       AbstractGangTask("G1 Free Collection Set"),
4316       _g1h(G1CollectedHeap::heap()),
4317       _evacuation_info(evacuation_info),
4318       _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4319       _claimer(active_workers),
4320       _surviving_young_words(surviving_young_words),
4321       _active_workers(active_workers) {
4322     for (uint worker = 0; worker < active_workers; worker++) {
4323       ::new (&_worker_stats[worker]) FreeCSetStats();
4324     }
4325   }
4326 
4327   ~G1FreeCollectionSetTask() {
4328     Ticks serial_time = Ticks::now();
4329     report_statistics();
4330     for (uint worker = 0; worker < _active_workers; worker++) {
4331       _worker_stats[worker].~FreeCSetStats();
4332     }
4333     FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4334     _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4335   }
4336 
4337   virtual void work(uint worker_id) {
4338     EventGCPhaseParallel event;
4339     Ticks start = Ticks::now();
4340     FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4341     _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4342 
4343     // Report the total parallel time along with some more detailed metrics.
4344     cl.report_timing(Ticks::now() - start);
4345     event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4346   }
4347 };
4348 
4349 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4350   _eden.clear();
4351 
4352   // The free collections set is split up in two tasks, the first
4353   // frees the collection set and records what regions are free,
4354   // and the second one rebuilds the free list. This proved to be
4355   // more efficient than adding a sorted list to another.
4356 
4357   Ticks free_cset_start_time = Ticks::now();
4358   {
4359     uint const num_cs_regions = _collection_set.region_length();
4360     uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4361     G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4362 
4363     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4364                         cl.name(), num_workers, num_cs_regions, num_regions());
4365     workers()->run_task(&cl, num_workers);
4366   }
4367 
4368   Ticks free_cset_end_time = Ticks::now();
4369   phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4370 
4371   // Now rebuild the free region list.
4372   hrm()->rebuild_free_list(workers());
4373   phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4374 
4375   collection_set->clear();
4376 }
4377 
4378 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4379  private:
4380   FreeRegionList* _free_region_list;
4381   HeapRegionSet* _proxy_set;
4382   uint _humongous_objects_reclaimed;
4383   uint _humongous_regions_reclaimed;
4384   size_t _freed_bytes;
4385  public:
4386 
4387   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4388     _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4389   }
4390 
4391   virtual bool do_heap_region(HeapRegion* r) {
4392     if (!r->is_starts_humongous()) {
4393       return false;
4394     }
4395 
4396     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4397 
4398     oop obj = (oop)r->bottom();
4399     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4400 
4401     // The following checks whether the humongous object is live are sufficient.
4402     // The main additional check (in addition to having a reference from the roots
4403     // or the young gen) is whether the humongous object has a remembered set entry.
4404     //
4405     // A humongous object cannot be live if there is no remembered set for it
4406     // because:
4407     // - there can be no references from within humongous starts regions referencing
4408     // the object because we never allocate other objects into them.
4409     // (I.e. there are no intra-region references that may be missed by the
4410     // remembered set)
4411     // - as soon there is a remembered set entry to the humongous starts region
4412     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4413     // until the end of a concurrent mark.
4414     //
4415     // It is not required to check whether the object has been found dead by marking
4416     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4417     // all objects allocated during that time are considered live.
4418     // SATB marking is even more conservative than the remembered set.
4419     // So if at this point in the collection there is no remembered set entry,
4420     // nobody has a reference to it.
4421     // At the start of collection we flush all refinement logs, and remembered sets
4422     // are completely up-to-date wrt to references to the humongous object.
4423     //
4424     // Other implementation considerations:
4425     // - never consider object arrays at this time because they would pose
4426     // considerable effort for cleaning up the the remembered sets. This is
4427     // required because stale remembered sets might reference locations that
4428     // are currently allocated into.
4429     uint region_idx = r->hrm_index();
4430     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4431         !r->rem_set()->is_empty()) {
4432       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",
4433                                region_idx,
4434                                (size_t)obj->size() * HeapWordSize,
4435                                p2i(r->bottom()),
4436                                r->rem_set()->occupied(),
4437                                r->rem_set()->strong_code_roots_list_length(),
4438                                next_bitmap->is_marked(r->bottom()),
4439                                g1h->is_humongous_reclaim_candidate(region_idx),
4440                                obj->is_typeArray()
4441                               );
4442       return false;
4443     }
4444 
4445     guarantee(obj->is_typeArray(),
4446               "Only eagerly reclaiming type arrays is supported, but the object "
4447               PTR_FORMAT " is not.", p2i(r->bottom()));
4448 
4449     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",
4450                              region_idx,
4451                              (size_t)obj->size() * HeapWordSize,
4452                              p2i(r->bottom()),
4453                              r->rem_set()->occupied(),
4454                              r->rem_set()->strong_code_roots_list_length(),
4455                              next_bitmap->is_marked(r->bottom()),
4456                              g1h->is_humongous_reclaim_candidate(region_idx),
4457                              obj->is_typeArray()
4458                             );
4459 
4460     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4461     cm->humongous_object_eagerly_reclaimed(r);
4462     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4463            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4464            region_idx,
4465            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4466            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4467     _humongous_objects_reclaimed++;
4468     do {
4469       HeapRegion* next = g1h->next_region_in_humongous(r);
4470       _freed_bytes += r->used();
4471       r->set_containing_set(NULL);
4472       _humongous_regions_reclaimed++;
4473       g1h->free_humongous_region(r, _free_region_list);
4474       r = next;
4475     } while (r != NULL);
4476 
4477     return false;
4478   }
4479 
4480   uint humongous_objects_reclaimed() {
4481     return _humongous_objects_reclaimed;
4482   }
4483 
4484   uint humongous_regions_reclaimed() {
4485     return _humongous_regions_reclaimed;
4486   }
4487 
4488   size_t bytes_freed() const {
4489     return _freed_bytes;
4490   }
4491 };
4492 
4493 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4494   assert_at_safepoint_on_vm_thread();
4495 
4496   if (!G1EagerReclaimHumongousObjects ||
4497       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4498     phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4499     return;
4500   }
4501 
4502   double start_time = os::elapsedTime();
4503 
4504   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4505 
4506   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4507   heap_region_iterate(&cl);
4508 
4509   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4510 
4511   G1HRPrinter* hrp = hr_printer();
4512   if (hrp->is_active()) {
4513     FreeRegionListIterator iter(&local_cleanup_list);
4514     while (iter.more_available()) {
4515       HeapRegion* hr = iter.get_next();
4516       hrp->cleanup(hr);
4517     }
4518   }
4519 
4520   prepend_to_freelist(&local_cleanup_list);
4521   decrement_summary_bytes(cl.bytes_freed());
4522 
4523   phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4524                                                        cl.humongous_objects_reclaimed());
4525 }
4526 
4527 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4528 public:
4529   virtual bool do_heap_region(HeapRegion* r) {
4530     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4531     G1CollectedHeap::heap()->clear_region_attr(r);
4532     r->clear_young_index_in_cset();
4533     return false;
4534   }
4535 };
4536 
4537 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4538   G1AbandonCollectionSetClosure cl;
4539   collection_set_iterate_all(&cl);
4540 
4541   collection_set->clear();
4542   collection_set->stop_incremental_building();
4543 }
4544 
4545 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4546   return _allocator->is_retained_old_region(hr);
4547 }
4548 
4549 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4550   _eden.add(hr);
4551   _policy->set_region_eden(hr);
4552 }
4553 
4554 #ifdef ASSERT
4555 
4556 class NoYoungRegionsClosure: public HeapRegionClosure {
4557 private:
4558   bool _success;
4559 public:
4560   NoYoungRegionsClosure() : _success(true) { }
4561   bool do_heap_region(HeapRegion* r) {
4562     if (r->is_young()) {
4563       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4564                             p2i(r->bottom()), p2i(r->end()));
4565       _success = false;
4566     }
4567     return false;
4568   }
4569   bool success() { return _success; }
4570 };
4571 
4572 bool G1CollectedHeap::check_young_list_empty() {
4573   bool ret = (young_regions_count() == 0);
4574 
4575   NoYoungRegionsClosure closure;
4576   heap_region_iterate(&closure);
4577   ret = ret && closure.success();
4578 
4579   return ret;
4580 }
4581 
4582 #endif // ASSERT
4583 
4584 class TearDownRegionSetsClosure : public HeapRegionClosure {
4585   HeapRegionSet *_old_set;
4586 
4587 public:
4588   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4589 
4590   bool do_heap_region(HeapRegion* r) {
4591     if (r->is_old()) {
4592       _old_set->remove(r);
4593     } else if(r->is_young()) {
4594       r->uninstall_surv_rate_group();
4595     } else {
4596       // We ignore free regions, we'll empty the free list afterwards.
4597       // We ignore humongous and archive regions, we're not tearing down these
4598       // sets.
4599       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4600              "it cannot be another type");
4601     }
4602     return false;
4603   }
4604 
4605   ~TearDownRegionSetsClosure() {
4606     assert(_old_set->is_empty(), "post-condition");
4607   }
4608 };
4609 
4610 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4611   assert_at_safepoint_on_vm_thread();
4612 
4613   if (!free_list_only) {
4614     TearDownRegionSetsClosure cl(&_old_set);
4615     heap_region_iterate(&cl);
4616 
4617     // Note that emptying the _young_list is postponed and instead done as
4618     // the first step when rebuilding the regions sets again. The reason for
4619     // this is that during a full GC string deduplication needs to know if
4620     // a collected region was young or old when the full GC was initiated.
4621   }
4622   _hrm->remove_all_free_regions();
4623 }
4624 
4625 void G1CollectedHeap::increase_used(size_t bytes) {
4626   _summary_bytes_used += bytes;
4627 }
4628 
4629 void G1CollectedHeap::decrease_used(size_t bytes) {
4630   assert(_summary_bytes_used >= bytes,
4631          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4632          _summary_bytes_used, bytes);
4633   _summary_bytes_used -= bytes;
4634 }
4635 
4636 void G1CollectedHeap::set_used(size_t bytes) {
4637   _summary_bytes_used = bytes;
4638 }
4639 
4640 class RebuildRegionSetsClosure : public HeapRegionClosure {
4641 private:
4642   bool _free_list_only;
4643 
4644   HeapRegionSet* _old_set;
4645   HeapRegionManager* _hrm;
4646 
4647   size_t _total_used;
4648 
4649 public:
4650   RebuildRegionSetsClosure(bool free_list_only,
4651                            HeapRegionSet* old_set,
4652                            HeapRegionManager* hrm) :
4653     _free_list_only(free_list_only),
4654     _old_set(old_set), _hrm(hrm), _total_used(0) {
4655     assert(_hrm->num_free_regions() == 0, "pre-condition");
4656     if (!free_list_only) {
4657       assert(_old_set->is_empty(), "pre-condition");
4658     }
4659   }
4660 
4661   bool do_heap_region(HeapRegion* r) {
4662     if (r->is_empty()) {
4663       assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4664       // Add free regions to the free list
4665       r->set_free();
4666       _hrm->insert_into_free_list(r);
4667     } else if (!_free_list_only) {
4668       assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4669 
4670       if (r->is_archive() || r->is_humongous()) {
4671         // We ignore archive and humongous regions. We left these sets unchanged.
4672       } else {
4673         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4674         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4675         r->move_to_old();
4676         _old_set->add(r);
4677       }
4678       _total_used += r->used();
4679     }
4680 
4681     return false;
4682   }
4683 
4684   size_t total_used() {
4685     return _total_used;
4686   }
4687 };
4688 
4689 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4690   assert_at_safepoint_on_vm_thread();
4691 
4692   if (!free_list_only) {
4693     _eden.clear();
4694     _survivor.clear();
4695   }
4696 
4697   RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4698   heap_region_iterate(&cl);
4699 
4700   if (!free_list_only) {
4701     set_used(cl.total_used());
4702     if (_archive_allocator != NULL) {
4703       _archive_allocator->clear_used();
4704     }
4705   }
4706   assert_used_and_recalculate_used_equal(this);
4707 }
4708 
4709 // Methods for the mutator alloc region
4710 
4711 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4712                                                       bool force,
4713                                                       uint node_index) {
4714   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4715   bool should_allocate = policy()->should_allocate_mutator_region();
4716   if (force || should_allocate) {
4717     HeapRegion* new_alloc_region = new_region(word_size,
4718                                               HeapRegionType::Eden,
4719                                               false /* do_expand */,
4720                                               node_index);
4721     if (new_alloc_region != NULL) {
4722       set_region_short_lived_locked(new_alloc_region);
4723       _hr_printer.alloc(new_alloc_region, !should_allocate);
4724       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4725       _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4726       return new_alloc_region;
4727     }
4728   }
4729   return NULL;
4730 }
4731 
4732 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4733                                                   size_t allocated_bytes) {
4734   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4735   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4736 
4737   collection_set()->add_eden_region(alloc_region);
4738   increase_used(allocated_bytes);
4739   _eden.add_used_bytes(allocated_bytes);
4740   _hr_printer.retire(alloc_region);
4741 
4742   // We update the eden sizes here, when the region is retired,
4743   // instead of when it's allocated, since this is the point that its
4744   // used space has been recorded in _summary_bytes_used.
4745   g1mm()->update_eden_size();
4746 }
4747 
4748 // Methods for the GC alloc regions
4749 
4750 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4751   if (dest.is_old()) {
4752     return true;
4753   } else {
4754     return survivor_regions_count() < policy()->max_survivor_regions();
4755   }
4756 }
4757 
4758 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4759   assert(FreeList_lock->owned_by_self(), "pre-condition");
4760 
4761   if (!has_more_regions(dest)) {
4762     return NULL;
4763   }
4764 
4765   HeapRegionType type;
4766   if (dest.is_young()) {
4767     type = HeapRegionType::Survivor;
4768   } else {
4769     type = HeapRegionType::Old;
4770   }
4771 
4772   HeapRegion* new_alloc_region = new_region(word_size,
4773                                             type,
4774                                             true /* do_expand */,
4775                                             node_index);
4776 
4777   if (new_alloc_region != NULL) {
4778     if (type.is_survivor()) {
4779       new_alloc_region->set_survivor();
4780       _survivor.add(new_alloc_region);
4781       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4782     } else {
4783       new_alloc_region->set_old();
4784       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4785     }
4786     _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4787     register_region_with_region_attr(new_alloc_region);
4788     _hr_printer.alloc(new_alloc_region);
4789     return new_alloc_region;
4790   }
4791   return NULL;
4792 }
4793 
4794 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4795                                              size_t allocated_bytes,
4796                                              G1HeapRegionAttr dest) {
4797   _bytes_used_during_gc += allocated_bytes;
4798   if (dest.is_old()) {
4799     old_set_add(alloc_region);
4800   } else {
4801     assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4802     _survivor.add_used_bytes(allocated_bytes);
4803   }
4804 
4805   bool const during_im = collector_state()->in_concurrent_start_gc();
4806   if (during_im && allocated_bytes > 0) {
4807     _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4808   }
4809   _hr_printer.retire(alloc_region);
4810 }
4811 
4812 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4813   bool expanded = false;
4814   uint index = _hrm->find_highest_free(&expanded);
4815 
4816   if (index != G1_NO_HRM_INDEX) {
4817     if (expanded) {
4818       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4819                                 HeapRegion::GrainWords * HeapWordSize);
4820     }
4821     return _hrm->allocate_free_regions_starting_at(index, 1);
4822   }
4823   return NULL;
4824 }
4825 
4826 // Optimized nmethod scanning
4827 
4828 class RegisterNMethodOopClosure: public OopClosure {
4829   G1CollectedHeap* _g1h;
4830   nmethod* _nm;
4831 
4832   template <class T> void do_oop_work(T* p) {
4833     T heap_oop = RawAccess<>::oop_load(p);
4834     if (!CompressedOops::is_null(heap_oop)) {
4835       oop obj = CompressedOops::decode_not_null(heap_oop);
4836       HeapRegion* hr = _g1h->heap_region_containing(obj);
4837       assert(!hr->is_continues_humongous(),
4838              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4839              " starting at " HR_FORMAT,
4840              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4841 
4842       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4843       hr->add_strong_code_root_locked(_nm);
4844     }
4845   }
4846 
4847 public:
4848   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4849     _g1h(g1h), _nm(nm) {}
4850 
4851   void do_oop(oop* p)       { do_oop_work(p); }
4852   void do_oop(narrowOop* p) { do_oop_work(p); }
4853 };
4854 
4855 class UnregisterNMethodOopClosure: public OopClosure {
4856   G1CollectedHeap* _g1h;
4857   nmethod* _nm;
4858 
4859   template <class T> void do_oop_work(T* p) {
4860     T heap_oop = RawAccess<>::oop_load(p);
4861     if (!CompressedOops::is_null(heap_oop)) {
4862       oop obj = CompressedOops::decode_not_null(heap_oop);
4863       HeapRegion* hr = _g1h->heap_region_containing(obj);
4864       assert(!hr->is_continues_humongous(),
4865              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4866              " starting at " HR_FORMAT,
4867              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4868 
4869       hr->remove_strong_code_root(_nm);
4870     }
4871   }
4872 
4873 public:
4874   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4875     _g1h(g1h), _nm(nm) {}
4876 
4877   void do_oop(oop* p)       { do_oop_work(p); }
4878   void do_oop(narrowOop* p) { do_oop_work(p); }
4879 };
4880 
4881 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4882   guarantee(nm != NULL, "sanity");
4883   RegisterNMethodOopClosure reg_cl(this, nm);
4884   nm->oops_do(&reg_cl);
4885 }
4886 
4887 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4888   guarantee(nm != NULL, "sanity");
4889   UnregisterNMethodOopClosure reg_cl(this, nm);
4890   nm->oops_do(&reg_cl, true);
4891 }
4892 
4893 void G1CollectedHeap::purge_code_root_memory() {
4894   double purge_start = os::elapsedTime();
4895   G1CodeRootSet::purge();
4896   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4897   phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4898 }
4899 
4900 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4901   G1CollectedHeap* _g1h;
4902 
4903 public:
4904   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4905     _g1h(g1h) {}
4906 
4907   void do_code_blob(CodeBlob* cb) {
4908     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4909     if (nm == NULL) {
4910       return;
4911     }
4912 
4913     _g1h->register_nmethod(nm);
4914   }
4915 };
4916 
4917 void G1CollectedHeap::rebuild_strong_code_roots() {
4918   RebuildStrongCodeRootClosure blob_cl(this);
4919   CodeCache::blobs_do(&blob_cl);
4920 }
4921 
4922 void G1CollectedHeap::initialize_serviceability() {
4923   _g1mm->initialize_serviceability();
4924 }
4925 
4926 MemoryUsage G1CollectedHeap::memory_usage() {
4927   return _g1mm->memory_usage();
4928 }
4929 
4930 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4931   return _g1mm->memory_managers();
4932 }
4933 
4934 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4935   return _g1mm->memory_pools();
4936 }
--- EOF ---