rev 60594 : [mq]: 8252086-remove-g1rs

   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   // Create space mappers.

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