1 /*
   2  * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoaderDataGraph.hpp"
  27 #include "classfile/metadataOnStackMark.hpp"
  28 #include "classfile/stringTable.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "gc/g1/g1Allocator.inline.hpp"
  32 #include "gc/g1/g1BarrierSet.hpp"
  33 #include "gc/g1/g1CollectedHeap.inline.hpp"
  34 #include "gc/g1/g1CollectionSet.hpp"
  35 #include "gc/g1/g1CollectorPolicy.hpp"
  36 #include "gc/g1/g1CollectorState.hpp"
  37 #include "gc/g1/g1ConcurrentRefine.hpp"
  38 #include "gc/g1/g1ConcurrentRefineThread.hpp"
  39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
  40 #include "gc/g1/g1DirtyCardQueue.hpp"
  41 #include "gc/g1/g1EvacStats.inline.hpp"
  42 #include "gc/g1/g1FullCollector.hpp"
  43 #include "gc/g1/g1GCPhaseTimes.hpp"
  44 #include "gc/g1/g1HeapSizingPolicy.hpp"
  45 #include "gc/g1/g1HeapTransition.hpp"
  46 #include "gc/g1/g1HeapVerifier.hpp"
  47 #include "gc/g1/g1HotCardCache.hpp"
  48 #include "gc/g1/g1MemoryPool.hpp"
  49 #include "gc/g1/g1OopClosures.inline.hpp"
  50 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  51 #include "gc/g1/g1Policy.hpp"
  52 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  53 #include "gc/g1/g1RemSet.hpp"
  54 #include "gc/g1/g1RootClosures.hpp"
  55 #include "gc/g1/g1RootProcessor.hpp"
  56 #include "gc/g1/g1SATBMarkQueueSet.hpp"
  57 #include "gc/g1/g1StringDedup.hpp"
  58 #include "gc/g1/g1ThreadLocalData.hpp"
  59 #include "gc/g1/g1YCTypes.hpp"
  60 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  61 #include "gc/g1/g1VMOperations.hpp"
  62 #include "gc/g1/heapRegion.inline.hpp"
  63 #include "gc/g1/heapRegionRemSet.hpp"
  64 #include "gc/g1/heapRegionSet.inline.hpp"
  65 #include "gc/shared/gcBehaviours.hpp"
  66 #include "gc/shared/gcHeapSummary.hpp"
  67 #include "gc/shared/gcId.hpp"
  68 #include "gc/shared/gcLocker.hpp"
  69 #include "gc/shared/gcTimer.hpp"
  70 #include "gc/shared/gcTrace.hpp"
  71 #include "gc/shared/gcTraceTime.inline.hpp"
  72 #include "gc/shared/generationSpec.hpp"
  73 #include "gc/shared/isGCActiveMark.hpp"
  74 #include "gc/shared/oopStorageParState.hpp"
  75 #include "gc/shared/parallelCleaning.hpp"
  76 #include "gc/shared/preservedMarks.inline.hpp"
  77 #include "gc/shared/suspendibleThreadSet.hpp"
  78 #include "gc/shared/referenceProcessor.inline.hpp"
  79 #include "gc/shared/taskqueue.inline.hpp"
  80 #include "gc/shared/weakProcessor.inline.hpp"
  81 #include "gc/shared/workerPolicy.hpp"
  82 #include "logging/log.hpp"
  83 #include "memory/allocation.hpp"
  84 #include "memory/iterator.hpp"
  85 #include "memory/resourceArea.hpp"
  86 #include "oops/access.inline.hpp"
  87 #include "oops/compressedOops.inline.hpp"
  88 #include "oops/oop.inline.hpp"
  89 #include "runtime/atomic.hpp"
  90 #include "runtime/flags/flagSetting.hpp"
  91 #include "runtime/handles.inline.hpp"
  92 #include "runtime/init.hpp"
  93 #include "runtime/orderAccess.hpp"
  94 #include "runtime/threadSMR.hpp"
  95 #include "runtime/vmThread.hpp"
  96 #include "utilities/align.hpp"
  97 #include "utilities/globalDefinitions.hpp"
  98 #include "utilities/stack.inline.hpp"
  99 
 100 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
 101 
 102 // INVARIANTS/NOTES
 103 //
 104 // All allocation activity covered by the G1CollectedHeap interface is
 105 // serialized by acquiring the HeapLock.  This happens in mem_allocate
 106 // and allocate_new_tlab, which are the "entry" points to the
 107 // allocation code from the rest of the JVM.  (Note that this does not
 108 // apply to TLAB allocation, which is not part of this interface: it
 109 // is done by clients of this interface.)
 110 
 111 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
 112  private:
 113   size_t _num_dirtied;
 114   G1CollectedHeap* _g1h;
 115   G1CardTable* _g1_ct;
 116 
 117   HeapRegion* region_for_card(CardValue* card_ptr) const {
 118     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
 119   }
 120 
 121   bool will_become_free(HeapRegion* hr) const {
 122     // A region will be freed by free_collection_set if the region is in the
 123     // collection set and has not had an evacuation failure.
 124     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 125   }
 126 
 127  public:
 128   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
 129     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
 130 
 131   bool do_card_ptr(CardValue* card_ptr, uint worker_i) {
 132     HeapRegion* hr = region_for_card(card_ptr);
 133 
 134     // Should only dirty cards in regions that won't be freed.
 135     if (!will_become_free(hr)) {
 136       *card_ptr = G1CardTable::dirty_card_val();
 137       _num_dirtied++;
 138     }
 139 
 140     return true;
 141   }
 142 
 143   size_t num_dirtied()   const { return _num_dirtied; }
 144 };
 145 
 146 
 147 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 148   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 149 }
 150 
 151 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 152   // The from card cache is not the memory that is actually committed. So we cannot
 153   // take advantage of the zero_filled parameter.
 154   reset_from_card_cache(start_idx, num_regions);
 155 }
 156 
 157 
 158 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 159                                              MemRegion mr) {
 160   return new HeapRegion(hrs_index, bot(), mr);
 161 }
 162 
 163 // Private methods.
 164 
 165 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) {
 166   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 167          "the only time we use this to allocate a humongous region is "
 168          "when we are allocating a single humongous region");
 169 
 170   HeapRegion* res = _hrm->allocate_free_region(type);
 171 
 172   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 173     // Currently, only attempts to allocate GC alloc regions set
 174     // do_expand to true. So, we should only reach here during a
 175     // safepoint. If this assumption changes we might have to
 176     // reconsider the use of _expand_heap_after_alloc_failure.
 177     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 178 
 179     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 180                               word_size * HeapWordSize);
 181 
 182     if (expand(word_size * HeapWordSize)) {
 183       // Given that expand() succeeded in expanding the heap, and we
 184       // always expand the heap by an amount aligned to the heap
 185       // region size, the free list should in theory not be empty.
 186       // In either case allocate_free_region() will check for NULL.
 187       res = _hrm->allocate_free_region(type);
 188     } else {
 189       _expand_heap_after_alloc_failure = false;
 190     }
 191   }
 192   return res;
 193 }
 194 
 195 HeapWord*
 196 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 197                                                            uint num_regions,
 198                                                            size_t word_size) {
 199   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 200   assert(is_humongous(word_size), "word_size should be humongous");
 201   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 202 
 203   // Index of last region in the series.
 204   uint last = first + num_regions - 1;
 205 
 206   // We need to initialize the region(s) we just discovered. This is
 207   // a bit tricky given that it can happen concurrently with
 208   // refinement threads refining cards on these regions and
 209   // potentially wanting to refine the BOT as they are scanning
 210   // those cards (this can happen shortly after a cleanup; see CR
 211   // 6991377). So we have to set up the region(s) carefully and in
 212   // a specific order.
 213 
 214   // The word size sum of all the regions we will allocate.
 215   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 216   assert(word_size <= word_size_sum, "sanity");
 217 
 218   // This will be the "starts humongous" region.
 219   HeapRegion* first_hr = region_at(first);
 220   // The header of the new object will be placed at the bottom of
 221   // the first region.
 222   HeapWord* new_obj = first_hr->bottom();
 223   // This will be the new top of the new object.
 224   HeapWord* obj_top = new_obj + word_size;
 225 
 226   // First, we need to zero the header of the space that we will be
 227   // allocating. When we update top further down, some refinement
 228   // threads might try to scan the region. By zeroing the header we
 229   // ensure that any thread that will try to scan the region will
 230   // come across the zero klass word and bail out.
 231   //
 232   // NOTE: It would not have been correct to have used
 233   // CollectedHeap::fill_with_object() and make the space look like
 234   // an int array. The thread that is doing the allocation will
 235   // later update the object header to a potentially different array
 236   // type and, for a very short period of time, the klass and length
 237   // fields will be inconsistent. This could cause a refinement
 238   // thread to calculate the object size incorrectly.
 239   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 240 
 241   // Next, pad out the unused tail of the last region with filler
 242   // objects, for improved usage accounting.
 243   // How many words we use for filler objects.
 244   size_t word_fill_size = word_size_sum - word_size;
 245 
 246   // How many words memory we "waste" which cannot hold a filler object.
 247   size_t words_not_fillable = 0;
 248 
 249   if (word_fill_size >= min_fill_size()) {
 250     fill_with_objects(obj_top, word_fill_size);
 251   } else if (word_fill_size > 0) {
 252     // We have space to fill, but we cannot fit an object there.
 253     words_not_fillable = word_fill_size;
 254     word_fill_size = 0;
 255   }
 256 
 257   // We will set up the first region as "starts humongous". This
 258   // will also update the BOT covering all the regions to reflect
 259   // that there is a single object that starts at the bottom of the
 260   // first region.
 261   first_hr->set_starts_humongous(obj_top, word_fill_size);
 262   _policy->remset_tracker()->update_at_allocate(first_hr);
 263   // Then, if there are any, we will set up the "continues
 264   // humongous" regions.
 265   HeapRegion* hr = NULL;
 266   for (uint i = first + 1; i <= last; ++i) {
 267     hr = region_at(i);
 268     hr->set_continues_humongous(first_hr);
 269     _policy->remset_tracker()->update_at_allocate(hr);
 270   }
 271 
 272   // Up to this point no concurrent thread would have been able to
 273   // do any scanning on any region in this series. All the top
 274   // fields still point to bottom, so the intersection between
 275   // [bottom,top] and [card_start,card_end] will be empty. Before we
 276   // update the top fields, we'll do a storestore to make sure that
 277   // no thread sees the update to top before the zeroing of the
 278   // object header and the BOT initialization.
 279   OrderAccess::storestore();
 280 
 281   // Now, we will update the top fields of the "continues humongous"
 282   // regions except the last one.
 283   for (uint i = first; i < last; ++i) {
 284     hr = region_at(i);
 285     hr->set_top(hr->end());
 286   }
 287 
 288   hr = region_at(last);
 289   // If we cannot fit a filler object, we must set top to the end
 290   // of the humongous object, otherwise we cannot iterate the heap
 291   // and the BOT will not be complete.
 292   hr->set_top(hr->end() - words_not_fillable);
 293 
 294   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 295          "obj_top should be in last region");
 296 
 297   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 298 
 299   assert(words_not_fillable == 0 ||
 300          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 301          "Miscalculation in humongous allocation");
 302 
 303   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 304 
 305   for (uint i = first; i <= last; ++i) {
 306     hr = region_at(i);
 307     _humongous_set.add(hr);
 308     _hr_printer.alloc(hr);
 309   }
 310 
 311   return new_obj;
 312 }
 313 
 314 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 315   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 316   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 317 }
 318 
 319 // If could fit into free regions w/o expansion, try.
 320 // Otherwise, if can expand, do so.
 321 // Otherwise, if using ex regions might help, try with ex given back.
 322 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 323   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 324 
 325   _verifier->verify_region_sets_optional();
 326 
 327   uint first = G1_NO_HRM_INDEX;
 328   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 329 
 330   if (obj_regions == 1) {
 331     // Only one region to allocate, try to use a fast path by directly allocating
 332     // from the free lists. Do not try to expand here, we will potentially do that
 333     // later.
 334     HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
 335     if (hr != NULL) {
 336       first = hr->hrm_index();
 337     }
 338   } else {
 339     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 340     // are lucky enough to find some.
 341     first = _hrm->find_contiguous_only_empty(obj_regions);
 342     if (first != G1_NO_HRM_INDEX) {
 343       _hrm->allocate_free_regions_starting_at(first, obj_regions);
 344     }
 345   }
 346 
 347   if (first == G1_NO_HRM_INDEX) {
 348     // Policy: We could not find enough regions for the humongous object in the
 349     // free list. Look through the heap to find a mix of free and uncommitted regions.
 350     // If so, try expansion.
 351     first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
 352     if (first != G1_NO_HRM_INDEX) {
 353       // We found something. Make sure these regions are committed, i.e. expand
 354       // the heap. Alternatively we could do a defragmentation GC.
 355       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 356                                     word_size * HeapWordSize);
 357 
 358       _hrm->expand_at(first, obj_regions, workers());
 359       policy()->record_new_heap_size(num_regions());
 360 
 361 #ifdef ASSERT
 362       for (uint i = first; i < first + obj_regions; ++i) {
 363         HeapRegion* hr = region_at(i);
 364         assert(hr->is_free(), "sanity");
 365         assert(hr->is_empty(), "sanity");
 366         assert(is_on_master_free_list(hr), "sanity");
 367       }
 368 #endif
 369       _hrm->allocate_free_regions_starting_at(first, obj_regions);
 370     } else {
 371       // Policy: Potentially trigger a defragmentation GC.
 372     }
 373   }
 374 
 375   HeapWord* result = NULL;
 376   if (first != G1_NO_HRM_INDEX) {
 377     result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
 378     assert(result != NULL, "it should always return a valid result");
 379 
 380     // A successful humongous object allocation changes the used space
 381     // information of the old generation so we need to recalculate the
 382     // sizes and update the jstat counters here.
 383     g1mm()->update_sizes();
 384   }
 385 
 386   _verifier->verify_region_sets_optional();
 387 
 388   return result;
 389 }
 390 
 391 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
 392                                              size_t requested_size,
 393                                              size_t* actual_size) {
 394   assert_heap_not_locked_and_not_at_safepoint();
 395   assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
 396 
 397   return attempt_allocation(min_size, requested_size, actual_size);
 398 }
 399 
 400 HeapWord*
 401 G1CollectedHeap::mem_allocate(size_t word_size,
 402                               bool*  gc_overhead_limit_was_exceeded) {
 403   assert_heap_not_locked_and_not_at_safepoint();
 404 
 405   if (is_humongous(word_size)) {
 406     return attempt_allocation_humongous(word_size);
 407   }
 408   size_t dummy = 0;
 409   return attempt_allocation(word_size, word_size, &dummy);
 410 }
 411 
 412 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 413   ResourceMark rm; // For retrieving the thread names in log messages.
 414 
 415   // Make sure you read the note in attempt_allocation_humongous().
 416 
 417   assert_heap_not_locked_and_not_at_safepoint();
 418   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 419          "be called for humongous allocation requests");
 420 
 421   // We should only get here after the first-level allocation attempt
 422   // (attempt_allocation()) failed to allocate.
 423 
 424   // We will loop until a) we manage to successfully perform the
 425   // allocation or b) we successfully schedule a collection which
 426   // fails to perform the allocation. b) is the only case when we'll
 427   // return NULL.
 428   HeapWord* result = NULL;
 429   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 430     bool should_try_gc;
 431     uint gc_count_before;
 432 
 433     {
 434       MutexLockerEx x(Heap_lock);
 435       result = _allocator->attempt_allocation_locked(word_size);
 436       if (result != NULL) {
 437         return result;
 438       }
 439 
 440       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 441       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 442       // waiting because the GCLocker is active to not wait too long.
 443       if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
 444         // No need for an ergo message here, can_expand_young_list() does this when
 445         // it returns true.
 446         result = _allocator->attempt_allocation_force(word_size);
 447         if (result != NULL) {
 448           return result;
 449         }
 450       }
 451       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 452       // the GCLocker initiated GC has been performed and then retry. This includes
 453       // the case when the GC Locker is not active but has not been performed.
 454       should_try_gc = !GCLocker::needs_gc();
 455       // Read the GC count while still holding the Heap_lock.
 456       gc_count_before = total_collections();
 457     }
 458 
 459     if (should_try_gc) {
 460       bool succeeded;
 461       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 462                                    GCCause::_g1_inc_collection_pause);
 463       if (result != NULL) {
 464         assert(succeeded, "only way to get back a non-NULL result");
 465         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 466                              Thread::current()->name(), p2i(result));
 467         return result;
 468       }
 469 
 470       if (succeeded) {
 471         // We successfully scheduled a collection which failed to allocate. No
 472         // point in trying to allocate further. We'll just return NULL.
 473         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 474                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 475         return NULL;
 476       }
 477       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 478                            Thread::current()->name(), word_size);
 479     } else {
 480       // Failed to schedule a collection.
 481       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 482         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 483                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 484         return NULL;
 485       }
 486       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 487       // The GCLocker is either active or the GCLocker initiated
 488       // GC has not yet been performed. Stall until it is and
 489       // then retry the allocation.
 490       GCLocker::stall_until_clear();
 491       gclocker_retry_count += 1;
 492     }
 493 
 494     // We can reach here if we were unsuccessful in scheduling a
 495     // collection (because another thread beat us to it) or if we were
 496     // stalled due to the GC locker. In either can we should retry the
 497     // allocation attempt in case another thread successfully
 498     // performed a collection and reclaimed enough space. We do the
 499     // first attempt (without holding the Heap_lock) here and the
 500     // follow-on attempt will be at the start of the next loop
 501     // iteration (after taking the Heap_lock).
 502     size_t dummy = 0;
 503     result = _allocator->attempt_allocation(word_size, word_size, &dummy);
 504     if (result != NULL) {
 505       return result;
 506     }
 507 
 508     // Give a warning if we seem to be looping forever.
 509     if ((QueuedAllocationWarningCount > 0) &&
 510         (try_count % QueuedAllocationWarningCount == 0)) {
 511       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 512                              Thread::current()->name(), try_count, word_size);
 513     }
 514   }
 515 
 516   ShouldNotReachHere();
 517   return NULL;
 518 }
 519 
 520 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 521   assert_at_safepoint_on_vm_thread();
 522   if (_archive_allocator == NULL) {
 523     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 524   }
 525 }
 526 
 527 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 528   // Allocations in archive regions cannot be of a size that would be considered
 529   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 530   // may be different at archive-restore time.
 531   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 532 }
 533 
 534 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 535   assert_at_safepoint_on_vm_thread();
 536   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 537   if (is_archive_alloc_too_large(word_size)) {
 538     return NULL;
 539   }
 540   return _archive_allocator->archive_mem_allocate(word_size);
 541 }
 542 
 543 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 544                                               size_t end_alignment_in_bytes) {
 545   assert_at_safepoint_on_vm_thread();
 546   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 547 
 548   // Call complete_archive to do the real work, filling in the MemRegion
 549   // array with the archive regions.
 550   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 551   delete _archive_allocator;
 552   _archive_allocator = NULL;
 553 }
 554 
 555 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 556   assert(ranges != NULL, "MemRegion array NULL");
 557   assert(count != 0, "No MemRegions provided");
 558   MemRegion reserved = _hrm->reserved();
 559   for (size_t i = 0; i < count; i++) {
 560     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 561       return false;
 562     }
 563   }
 564   return true;
 565 }
 566 
 567 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 568                                             size_t count,
 569                                             bool open) {
 570   assert(!is_init_completed(), "Expect to be called at JVM init time");
 571   assert(ranges != NULL, "MemRegion array NULL");
 572   assert(count != 0, "No MemRegions provided");
 573   MutexLockerEx x(Heap_lock);
 574 
 575   MemRegion reserved = _hrm->reserved();
 576   HeapWord* prev_last_addr = NULL;
 577   HeapRegion* prev_last_region = NULL;
 578 
 579   // Temporarily disable pretouching of heap pages. This interface is used
 580   // when mmap'ing archived heap data in, so pre-touching is wasted.
 581   FlagSetting fs(AlwaysPreTouch, false);
 582 
 583   // Enable archive object checking used by G1MarkSweep. We have to let it know
 584   // about each archive range, so that objects in those ranges aren't marked.
 585   G1ArchiveAllocator::enable_archive_object_check();
 586 
 587   // For each specified MemRegion range, allocate the corresponding G1
 588   // regions and mark them as archive regions. We expect the ranges
 589   // in ascending starting address order, without overlap.
 590   for (size_t i = 0; i < count; i++) {
 591     MemRegion curr_range = ranges[i];
 592     HeapWord* start_address = curr_range.start();
 593     size_t word_size = curr_range.word_size();
 594     HeapWord* last_address = curr_range.last();
 595     size_t commits = 0;
 596 
 597     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 598               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 599               p2i(start_address), p2i(last_address));
 600     guarantee(start_address > prev_last_addr,
 601               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 602               p2i(start_address), p2i(prev_last_addr));
 603     prev_last_addr = last_address;
 604 
 605     // Check for ranges that start in the same G1 region in which the previous
 606     // range ended, and adjust the start address so we don't try to allocate
 607     // the same region again. If the current range is entirely within that
 608     // region, skip it, just adjusting the recorded top.
 609     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 610     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 611       start_address = start_region->end();
 612       if (start_address > last_address) {
 613         increase_used(word_size * HeapWordSize);
 614         start_region->set_top(last_address + 1);
 615         continue;
 616       }
 617       start_region->set_top(start_address);
 618       curr_range = MemRegion(start_address, last_address + 1);
 619       start_region = _hrm->addr_to_region(start_address);
 620     }
 621 
 622     // Perform the actual region allocation, exiting if it fails.
 623     // Then note how much new space we have allocated.
 624     if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
 625       return false;
 626     }
 627     increase_used(word_size * HeapWordSize);
 628     if (commits != 0) {
 629       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 630                                 HeapRegion::GrainWords * HeapWordSize * commits);
 631 
 632     }
 633 
 634     // Mark each G1 region touched by the range as archive, add it to
 635     // the old set, and set top.
 636     HeapRegion* curr_region = _hrm->addr_to_region(start_address);
 637     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 638     prev_last_region = last_region;
 639 
 640     while (curr_region != NULL) {
 641       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 642              "Region already in use (index %u)", curr_region->hrm_index());
 643       if (open) {
 644         curr_region->set_open_archive();
 645       } else {
 646         curr_region->set_closed_archive();
 647       }
 648       _hr_printer.alloc(curr_region);
 649       _archive_set.add(curr_region);
 650       HeapWord* top;
 651       HeapRegion* next_region;
 652       if (curr_region != last_region) {
 653         top = curr_region->end();
 654         next_region = _hrm->next_region_in_heap(curr_region);
 655       } else {
 656         top = last_address + 1;
 657         next_region = NULL;
 658       }
 659       curr_region->set_top(top);
 660       curr_region->set_first_dead(top);
 661       curr_region->set_end_of_live(top);
 662       curr_region = next_region;
 663     }
 664 
 665     // Notify mark-sweep of the archive
 666     G1ArchiveAllocator::set_range_archive(curr_range, open);
 667   }
 668   return true;
 669 }
 670 
 671 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 672   assert(!is_init_completed(), "Expect to be called at JVM init time");
 673   assert(ranges != NULL, "MemRegion array NULL");
 674   assert(count != 0, "No MemRegions provided");
 675   MemRegion reserved = _hrm->reserved();
 676   HeapWord *prev_last_addr = NULL;
 677   HeapRegion* prev_last_region = NULL;
 678 
 679   // For each MemRegion, create filler objects, if needed, in the G1 regions
 680   // that contain the address range. The address range actually within the
 681   // MemRegion will not be modified. That is assumed to have been initialized
 682   // elsewhere, probably via an mmap of archived heap data.
 683   MutexLockerEx x(Heap_lock);
 684   for (size_t i = 0; i < count; i++) {
 685     HeapWord* start_address = ranges[i].start();
 686     HeapWord* last_address = ranges[i].last();
 687 
 688     assert(reserved.contains(start_address) && reserved.contains(last_address),
 689            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 690            p2i(start_address), p2i(last_address));
 691     assert(start_address > prev_last_addr,
 692            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 693            p2i(start_address), p2i(prev_last_addr));
 694 
 695     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 696     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 697     HeapWord* bottom_address = start_region->bottom();
 698 
 699     // Check for a range beginning in the same region in which the
 700     // previous one ended.
 701     if (start_region == prev_last_region) {
 702       bottom_address = prev_last_addr + 1;
 703     }
 704 
 705     // Verify that the regions were all marked as archive regions by
 706     // alloc_archive_regions.
 707     HeapRegion* curr_region = start_region;
 708     while (curr_region != NULL) {
 709       guarantee(curr_region->is_archive(),
 710                 "Expected archive region at index %u", curr_region->hrm_index());
 711       if (curr_region != last_region) {
 712         curr_region = _hrm->next_region_in_heap(curr_region);
 713       } else {
 714         curr_region = NULL;
 715       }
 716     }
 717 
 718     prev_last_addr = last_address;
 719     prev_last_region = last_region;
 720 
 721     // Fill the memory below the allocated range with dummy object(s),
 722     // if the region bottom does not match the range start, or if the previous
 723     // range ended within the same G1 region, and there is a gap.
 724     if (start_address != bottom_address) {
 725       size_t fill_size = pointer_delta(start_address, bottom_address);
 726       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 727       increase_used(fill_size * HeapWordSize);
 728     }
 729   }
 730 }
 731 
 732 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
 733                                                      size_t desired_word_size,
 734                                                      size_t* actual_word_size) {
 735   assert_heap_not_locked_and_not_at_safepoint();
 736   assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
 737          "be called for humongous allocation requests");
 738 
 739   HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
 740 
 741   if (result == NULL) {
 742     *actual_word_size = desired_word_size;
 743     result = attempt_allocation_slow(desired_word_size);
 744   }
 745 
 746   assert_heap_not_locked();
 747   if (result != NULL) {
 748     assert(*actual_word_size != 0, "Actual size must have been set here");
 749     dirty_young_block(result, *actual_word_size);
 750   } else {
 751     *actual_word_size = 0;
 752   }
 753 
 754   return result;
 755 }
 756 
 757 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
 758   assert(!is_init_completed(), "Expect to be called at JVM init time");
 759   assert(ranges != NULL, "MemRegion array NULL");
 760   assert(count != 0, "No MemRegions provided");
 761   MemRegion reserved = _hrm->reserved();
 762   HeapWord* prev_last_addr = NULL;
 763   HeapRegion* prev_last_region = NULL;
 764   size_t size_used = 0;
 765   size_t uncommitted_regions = 0;
 766 
 767   // For each Memregion, free the G1 regions that constitute it, and
 768   // notify mark-sweep that the range is no longer to be considered 'archive.'
 769   MutexLockerEx x(Heap_lock);
 770   for (size_t i = 0; i < count; i++) {
 771     HeapWord* start_address = ranges[i].start();
 772     HeapWord* last_address = ranges[i].last();
 773 
 774     assert(reserved.contains(start_address) && reserved.contains(last_address),
 775            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 776            p2i(start_address), p2i(last_address));
 777     assert(start_address > prev_last_addr,
 778            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 779            p2i(start_address), p2i(prev_last_addr));
 780     size_used += ranges[i].byte_size();
 781     prev_last_addr = last_address;
 782 
 783     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 784     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 785 
 786     // Check for ranges that start in the same G1 region in which the previous
 787     // range ended, and adjust the start address so we don't try to free
 788     // the same region again. If the current range is entirely within that
 789     // region, skip it.
 790     if (start_region == prev_last_region) {
 791       start_address = start_region->end();
 792       if (start_address > last_address) {
 793         continue;
 794       }
 795       start_region = _hrm->addr_to_region(start_address);
 796     }
 797     prev_last_region = last_region;
 798 
 799     // After verifying that each region was marked as an archive region by
 800     // alloc_archive_regions, set it free and empty and uncommit it.
 801     HeapRegion* curr_region = start_region;
 802     while (curr_region != NULL) {
 803       guarantee(curr_region->is_archive(),
 804                 "Expected archive region at index %u", curr_region->hrm_index());
 805       uint curr_index = curr_region->hrm_index();
 806       _archive_set.remove(curr_region);
 807       curr_region->set_free();
 808       curr_region->set_top(curr_region->bottom());
 809       if (curr_region != last_region) {
 810         curr_region = _hrm->next_region_in_heap(curr_region);
 811       } else {
 812         curr_region = NULL;
 813       }
 814       _hrm->shrink_at(curr_index, 1);
 815       uncommitted_regions++;
 816     }
 817 
 818     // Notify mark-sweep that this is no longer an archive range.
 819     G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
 820   }
 821 
 822   if (uncommitted_regions != 0) {
 823     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 824                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 825   }
 826   decrease_used(size_used);
 827 }
 828 
 829 oop G1CollectedHeap::materialize_archived_object(oop obj) {
 830   assert(obj != NULL, "archived obj is NULL");
 831   assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
 832 
 833   // Loading an archived object makes it strongly reachable. If it is
 834   // loaded during concurrent marking, it must be enqueued to the SATB
 835   // queue, shading the previously white object gray.
 836   G1BarrierSet::enqueue(obj);
 837 
 838   return obj;
 839 }
 840 
 841 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 842   ResourceMark rm; // For retrieving the thread names in log messages.
 843 
 844   // The structure of this method has a lot of similarities to
 845   // attempt_allocation_slow(). The reason these two were not merged
 846   // into a single one is that such a method would require several "if
 847   // allocation is not humongous do this, otherwise do that"
 848   // conditional paths which would obscure its flow. In fact, an early
 849   // version of this code did use a unified method which was harder to
 850   // follow and, as a result, it had subtle bugs that were hard to
 851   // track down. So keeping these two methods separate allows each to
 852   // be more readable. It will be good to keep these two in sync as
 853   // much as possible.
 854 
 855   assert_heap_not_locked_and_not_at_safepoint();
 856   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 857          "should only be called for humongous allocations");
 858 
 859   // Humongous objects can exhaust the heap quickly, so we should check if we
 860   // need to start a marking cycle at each humongous object allocation. We do
 861   // the check before we do the actual allocation. The reason for doing it
 862   // before the allocation is that we avoid having to keep track of the newly
 863   // allocated memory while we do a GC.
 864   if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
 865                                            word_size)) {
 866     collect(GCCause::_g1_humongous_allocation);
 867   }
 868 
 869   // We will loop until a) we manage to successfully perform the
 870   // allocation or b) we successfully schedule a collection which
 871   // fails to perform the allocation. b) is the only case when we'll
 872   // return NULL.
 873   HeapWord* result = NULL;
 874   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 875     bool should_try_gc;
 876     uint gc_count_before;
 877 
 878 
 879     {
 880       MutexLockerEx x(Heap_lock);
 881 
 882       // Given that humongous objects are not allocated in young
 883       // regions, we'll first try to do the allocation without doing a
 884       // collection hoping that there's enough space in the heap.
 885       result = humongous_obj_allocate(word_size);
 886       if (result != NULL) {
 887         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 888         policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 889         return result;
 890       }
 891 
 892       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 893       // the GCLocker initiated GC has been performed and then retry. This includes
 894       // the case when the GC Locker is not active but has not been performed.
 895       should_try_gc = !GCLocker::needs_gc();
 896       // Read the GC count while still holding the Heap_lock.
 897       gc_count_before = total_collections();
 898     }
 899 
 900     if (should_try_gc) {
 901       bool succeeded;
 902       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 903                                    GCCause::_g1_humongous_allocation);
 904       if (result != NULL) {
 905         assert(succeeded, "only way to get back a non-NULL result");
 906         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 907                              Thread::current()->name(), p2i(result));
 908         return result;
 909       }
 910 
 911       if (succeeded) {
 912         // We successfully scheduled a collection which failed to allocate. No
 913         // point in trying to allocate further. We'll just return NULL.
 914         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 915                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 916         return NULL;
 917       }
 918       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 919                            Thread::current()->name(), word_size);
 920     } else {
 921       // Failed to schedule a collection.
 922       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 923         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 924                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 925         return NULL;
 926       }
 927       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 928       // The GCLocker is either active or the GCLocker initiated
 929       // GC has not yet been performed. Stall until it is and
 930       // then retry the allocation.
 931       GCLocker::stall_until_clear();
 932       gclocker_retry_count += 1;
 933     }
 934 
 935 
 936     // We can reach here if we were unsuccessful in scheduling a
 937     // collection (because another thread beat us to it) or if we were
 938     // stalled due to the GC locker. In either can we should retry the
 939     // allocation attempt in case another thread successfully
 940     // performed a collection and reclaimed enough space.
 941     // Humongous object allocation always needs a lock, so we wait for the retry
 942     // in the next iteration of the loop, unlike for the regular iteration case.
 943     // Give a warning if we seem to be looping forever.
 944 
 945     if ((QueuedAllocationWarningCount > 0) &&
 946         (try_count % QueuedAllocationWarningCount == 0)) {
 947       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 948                              Thread::current()->name(), try_count, word_size);
 949     }
 950   }
 951 
 952   ShouldNotReachHere();
 953   return NULL;
 954 }
 955 
 956 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 957                                                            bool expect_null_mutator_alloc_region) {
 958   assert_at_safepoint_on_vm_thread();
 959   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 960          "the current alloc region was unexpectedly found to be non-NULL");
 961 
 962   if (!is_humongous(word_size)) {
 963     return _allocator->attempt_allocation_locked(word_size);
 964   } else {
 965     HeapWord* result = humongous_obj_allocate(word_size);
 966     if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
 967       collector_state()->set_initiate_conc_mark_if_possible(true);
 968     }
 969     return result;
 970   }
 971 
 972   ShouldNotReachHere();
 973 }
 974 
 975 class PostCompactionPrinterClosure: public HeapRegionClosure {
 976 private:
 977   G1HRPrinter* _hr_printer;
 978 public:
 979   bool do_heap_region(HeapRegion* hr) {
 980     assert(!hr->is_young(), "not expecting to find young regions");
 981     _hr_printer->post_compaction(hr);
 982     return false;
 983   }
 984 
 985   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 986     : _hr_printer(hr_printer) { }
 987 };
 988 
 989 void G1CollectedHeap::print_hrm_post_compaction() {
 990   if (_hr_printer.is_active()) {
 991     PostCompactionPrinterClosure cl(hr_printer());
 992     heap_region_iterate(&cl);
 993   }
 994 }
 995 
 996 void G1CollectedHeap::abort_concurrent_cycle() {
 997   // If we start the compaction before the CM threads finish
 998   // scanning the root regions we might trip them over as we'll
 999   // be moving objects / updating references. So let's wait until
1000   // they are done. By telling them to abort, they should complete
1001   // early.
1002   _cm->root_regions()->abort();
1003   _cm->root_regions()->wait_until_scan_finished();
1004 
1005   // Disable discovery and empty the discovered lists
1006   // for the CM ref processor.
1007   _ref_processor_cm->disable_discovery();
1008   _ref_processor_cm->abandon_partial_discovery();
1009   _ref_processor_cm->verify_no_references_recorded();
1010 
1011   // Abandon current iterations of concurrent marking and concurrent
1012   // refinement, if any are in progress.
1013   concurrent_mark()->concurrent_cycle_abort();
1014 }
1015 
1016 void G1CollectedHeap::prepare_heap_for_full_collection() {
1017   // Make sure we'll choose a new allocation region afterwards.
1018   _allocator->release_mutator_alloc_region();
1019   _allocator->abandon_gc_alloc_regions();
1020 
1021   // We may have added regions to the current incremental collection
1022   // set between the last GC or pause and now. We need to clear the
1023   // incremental collection set and then start rebuilding it afresh
1024   // after this full GC.
1025   abandon_collection_set(collection_set());
1026 
1027   tear_down_region_sets(false /* free_list_only */);
1028 
1029   hrm()->prepare_for_full_collection_start();
1030 }
1031 
1032 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1033   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1034   assert(used() == recalculate_used(), "Should be equal");
1035   _verifier->verify_region_sets_optional();
1036   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1037   _verifier->check_bitmaps("Full GC Start");
1038 }
1039 
1040 void G1CollectedHeap::prepare_heap_for_mutators() {
1041   hrm()->prepare_for_full_collection_end();
1042 
1043   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1044   ClassLoaderDataGraph::purge();
1045   MetaspaceUtils::verify_metrics();
1046 
1047   // Prepare heap for normal collections.
1048   assert(num_free_regions() == 0, "we should not have added any free regions");
1049   rebuild_region_sets(false /* free_list_only */);
1050   abort_refinement();
1051   resize_heap_if_necessary();
1052 
1053   // Rebuild the strong code root lists for each region
1054   rebuild_strong_code_roots();
1055 
1056   // Purge code root memory
1057   purge_code_root_memory();
1058 
1059   // Start a new incremental collection set for the next pause
1060   start_new_collection_set();
1061 
1062   _allocator->init_mutator_alloc_region();
1063 
1064   // Post collection state updates.
1065   MetaspaceGC::compute_new_size();
1066 }
1067 
1068 void G1CollectedHeap::abort_refinement() {
1069   if (_hot_card_cache->use_cache()) {
1070     _hot_card_cache->reset_hot_cache();
1071   }
1072 
1073   // Discard all remembered set updates.
1074   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1075   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1076 }
1077 
1078 void G1CollectedHeap::verify_after_full_collection() {
1079   _hrm->verify_optional();
1080   _verifier->verify_region_sets_optional();
1081   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1082   // Clear the previous marking bitmap, if needed for bitmap verification.
1083   // Note we cannot do this when we clear the next marking bitmap in
1084   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1085   // objects marked during a full GC against the previous bitmap.
1086   // But we need to clear it before calling check_bitmaps below since
1087   // the full GC has compacted objects and updated TAMS but not updated
1088   // the prev bitmap.
1089   if (G1VerifyBitmaps) {
1090     GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification");
1091     _cm->clear_prev_bitmap(workers());
1092   }
1093   // This call implicitly verifies that the next bitmap is clear after Full GC.
1094   _verifier->check_bitmaps("Full GC End");
1095 
1096   // At this point there should be no regions in the
1097   // entire heap tagged as young.
1098   assert(check_young_list_empty(), "young list should be empty at this point");
1099 
1100   // Note: since we've just done a full GC, concurrent
1101   // marking is no longer active. Therefore we need not
1102   // re-enable reference discovery for the CM ref processor.
1103   // That will be done at the start of the next marking cycle.
1104   // We also know that the STW processor should no longer
1105   // discover any new references.
1106   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1107   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1108   _ref_processor_stw->verify_no_references_recorded();
1109   _ref_processor_cm->verify_no_references_recorded();
1110 }
1111 
1112 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1113   // Post collection logging.
1114   // We should do this after we potentially resize the heap so
1115   // that all the COMMIT / UNCOMMIT events are generated before
1116   // the compaction events.
1117   print_hrm_post_compaction();
1118   heap_transition->print();
1119   print_heap_after_gc();
1120   print_heap_regions();
1121 #ifdef TRACESPINNING
1122   ParallelTaskTerminator::print_termination_counts();
1123 #endif
1124 }
1125 
1126 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1127                                          bool clear_all_soft_refs) {
1128   assert_at_safepoint_on_vm_thread();
1129 
1130   if (GCLocker::check_active_before_gc()) {
1131     // Full GC was not completed.
1132     return false;
1133   }
1134 
1135   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1136       soft_ref_policy()->should_clear_all_soft_refs();
1137 
1138   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1139   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1140 
1141   collector.prepare_collection();
1142   collector.collect();
1143   collector.complete_collection();
1144 
1145   // Full collection was successfully completed.
1146   return true;
1147 }
1148 
1149 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1150   // Currently, there is no facility in the do_full_collection(bool) API to notify
1151   // the caller that the collection did not succeed (e.g., because it was locked
1152   // out by the GC locker). So, right now, we'll ignore the return value.
1153   bool dummy = do_full_collection(true,                /* explicit_gc */
1154                                   clear_all_soft_refs);
1155 }
1156 
1157 void G1CollectedHeap::resize_heap_if_necessary() {
1158   assert_at_safepoint_on_vm_thread();
1159 
1160   // Capacity, free and used after the GC counted as full regions to
1161   // include the waste in the following calculations.
1162   const size_t capacity_after_gc = capacity();
1163   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1164 
1165   // This is enforced in arguments.cpp.
1166   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1167          "otherwise the code below doesn't make sense");
1168 
1169   // We don't have floating point command-line arguments
1170   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1171   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1172   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1173   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1174 
1175   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1176   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1177 
1178   // We have to be careful here as these two calculations can overflow
1179   // 32-bit size_t's.
1180   double used_after_gc_d = (double) used_after_gc;
1181   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1182   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1183 
1184   // Let's make sure that they are both under the max heap size, which
1185   // by default will make them fit into a size_t.
1186   double desired_capacity_upper_bound = (double) max_heap_size;
1187   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1188                                     desired_capacity_upper_bound);
1189   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1190                                     desired_capacity_upper_bound);
1191 
1192   // We can now safely turn them into size_t's.
1193   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1194   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1195 
1196   // This assert only makes sense here, before we adjust them
1197   // with respect to the min and max heap size.
1198   assert(minimum_desired_capacity <= maximum_desired_capacity,
1199          "minimum_desired_capacity = " SIZE_FORMAT ", "
1200          "maximum_desired_capacity = " SIZE_FORMAT,
1201          minimum_desired_capacity, maximum_desired_capacity);
1202 
1203   // Should not be greater than the heap max size. No need to adjust
1204   // it with respect to the heap min size as it's a lower bound (i.e.,
1205   // we'll try to make the capacity larger than it, not smaller).
1206   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1207   // Should not be less than the heap min size. No need to adjust it
1208   // with respect to the heap max size as it's an upper bound (i.e.,
1209   // we'll try to make the capacity smaller than it, not greater).
1210   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1211 
1212   if (capacity_after_gc < minimum_desired_capacity) {
1213     // Don't expand unless it's significant
1214     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1215 
1216     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1217                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1218                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1219                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1220 
1221     expand(expand_bytes, _workers);
1222 
1223     // No expansion, now see if we want to shrink
1224   } else if (capacity_after_gc > maximum_desired_capacity) {
1225     // Capacity too large, compute shrinking size
1226     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1227 
1228     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1229                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1230                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1231                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1232 
1233     shrink(shrink_bytes);
1234   }
1235 }
1236 
1237 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1238                                                             bool do_gc,
1239                                                             bool clear_all_soft_refs,
1240                                                             bool expect_null_mutator_alloc_region,
1241                                                             bool* gc_succeeded) {
1242   *gc_succeeded = true;
1243   // Let's attempt the allocation first.
1244   HeapWord* result =
1245     attempt_allocation_at_safepoint(word_size,
1246                                     expect_null_mutator_alloc_region);
1247   if (result != NULL) {
1248     return result;
1249   }
1250 
1251   // In a G1 heap, we're supposed to keep allocation from failing by
1252   // incremental pauses.  Therefore, at least for now, we'll favor
1253   // expansion over collection.  (This might change in the future if we can
1254   // do something smarter than full collection to satisfy a failed alloc.)
1255   result = expand_and_allocate(word_size);
1256   if (result != NULL) {
1257     return result;
1258   }
1259 
1260   if (do_gc) {
1261     // Expansion didn't work, we'll try to do a Full GC.
1262     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1263                                        clear_all_soft_refs);
1264   }
1265 
1266   return NULL;
1267 }
1268 
1269 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1270                                                      bool* succeeded) {
1271   assert_at_safepoint_on_vm_thread();
1272 
1273   // Attempts to allocate followed by Full GC.
1274   HeapWord* result =
1275     satisfy_failed_allocation_helper(word_size,
1276                                      true,  /* do_gc */
1277                                      false, /* clear_all_soft_refs */
1278                                      false, /* expect_null_mutator_alloc_region */
1279                                      succeeded);
1280 
1281   if (result != NULL || !*succeeded) {
1282     return result;
1283   }
1284 
1285   // Attempts to allocate followed by Full GC that will collect all soft references.
1286   result = satisfy_failed_allocation_helper(word_size,
1287                                             true, /* do_gc */
1288                                             true, /* clear_all_soft_refs */
1289                                             true, /* expect_null_mutator_alloc_region */
1290                                             succeeded);
1291 
1292   if (result != NULL || !*succeeded) {
1293     return result;
1294   }
1295 
1296   // Attempts to allocate, no GC
1297   result = satisfy_failed_allocation_helper(word_size,
1298                                             false, /* do_gc */
1299                                             false, /* clear_all_soft_refs */
1300                                             true,  /* expect_null_mutator_alloc_region */
1301                                             succeeded);
1302 
1303   if (result != NULL) {
1304     return result;
1305   }
1306 
1307   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1308          "Flag should have been handled and cleared prior to this point");
1309 
1310   // What else?  We might try synchronous finalization later.  If the total
1311   // space available is large enough for the allocation, then a more
1312   // complete compaction phase than we've tried so far might be
1313   // appropriate.
1314   return NULL;
1315 }
1316 
1317 // Attempting to expand the heap sufficiently
1318 // to support an allocation of the given "word_size".  If
1319 // successful, perform the allocation and return the address of the
1320 // allocated block, or else "NULL".
1321 
1322 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1323   assert_at_safepoint_on_vm_thread();
1324 
1325   _verifier->verify_region_sets_optional();
1326 
1327   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1328   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1329                             word_size * HeapWordSize);
1330 
1331 
1332   if (expand(expand_bytes, _workers)) {
1333     _hrm->verify_optional();
1334     _verifier->verify_region_sets_optional();
1335     return attempt_allocation_at_safepoint(word_size,
1336                                            false /* expect_null_mutator_alloc_region */);
1337   }
1338   return NULL;
1339 }
1340 
1341 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1342   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1343   aligned_expand_bytes = align_up(aligned_expand_bytes,
1344                                        HeapRegion::GrainBytes);
1345 
1346   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1347                             expand_bytes, aligned_expand_bytes);
1348 
1349   if (is_maximal_no_gc()) {
1350     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1351     return false;
1352   }
1353 
1354   double expand_heap_start_time_sec = os::elapsedTime();
1355   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1356   assert(regions_to_expand > 0, "Must expand by at least one region");
1357 
1358   uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1359   if (expand_time_ms != NULL) {
1360     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1361   }
1362 
1363   if (expanded_by > 0) {
1364     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1365     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1366     policy()->record_new_heap_size(num_regions());
1367   } else {
1368     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1369 
1370     // The expansion of the virtual storage space was unsuccessful.
1371     // Let's see if it was because we ran out of swap.
1372     if (G1ExitOnExpansionFailure &&
1373         _hrm->available() >= regions_to_expand) {
1374       // We had head room...
1375       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1376     }
1377   }
1378   return regions_to_expand > 0;
1379 }
1380 
1381 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1382   size_t aligned_shrink_bytes =
1383     ReservedSpace::page_align_size_down(shrink_bytes);
1384   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1385                                          HeapRegion::GrainBytes);
1386   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1387 
1388   uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1389   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1390 
1391 
1392   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",
1393                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1394   if (num_regions_removed > 0) {
1395     policy()->record_new_heap_size(num_regions());
1396   } else {
1397     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1398   }
1399 }
1400 
1401 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1402   _verifier->verify_region_sets_optional();
1403 
1404   // We should only reach here at the end of a Full GC or during Remark which
1405   // means we should not not be holding to any GC alloc regions. The method
1406   // below will make sure of that and do any remaining clean up.
1407   _allocator->abandon_gc_alloc_regions();
1408 
1409   // Instead of tearing down / rebuilding the free lists here, we
1410   // could instead use the remove_all_pending() method on free_list to
1411   // remove only the ones that we need to remove.
1412   tear_down_region_sets(true /* free_list_only */);
1413   shrink_helper(shrink_bytes);
1414   rebuild_region_sets(true /* free_list_only */);
1415 
1416   _hrm->verify_optional();
1417   _verifier->verify_region_sets_optional();
1418 }
1419 
1420 class OldRegionSetChecker : public HeapRegionSetChecker {
1421 public:
1422   void check_mt_safety() {
1423     // Master Old Set MT safety protocol:
1424     // (a) If we're at a safepoint, operations on the master old set
1425     // should be invoked:
1426     // - by the VM thread (which will serialize them), or
1427     // - by the GC workers while holding the FreeList_lock, if we're
1428     //   at a safepoint for an evacuation pause (this lock is taken
1429     //   anyway when an GC alloc region is retired so that a new one
1430     //   is allocated from the free list), or
1431     // - by the GC workers while holding the OldSets_lock, if we're at a
1432     //   safepoint for a cleanup pause.
1433     // (b) If we're not at a safepoint, operations on the master old set
1434     // should be invoked while holding the Heap_lock.
1435 
1436     if (SafepointSynchronize::is_at_safepoint()) {
1437       guarantee(Thread::current()->is_VM_thread() ||
1438                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1439                 "master old set MT safety protocol at a safepoint");
1440     } else {
1441       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1442     }
1443   }
1444   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1445   const char* get_description() { return "Old Regions"; }
1446 };
1447 
1448 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1449 public:
1450   void check_mt_safety() {
1451     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1452               "May only change archive regions during initialization or safepoint.");
1453   }
1454   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1455   const char* get_description() { return "Archive Regions"; }
1456 };
1457 
1458 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1459 public:
1460   void check_mt_safety() {
1461     // Humongous Set MT safety protocol:
1462     // (a) If we're at a safepoint, operations on the master humongous
1463     // set should be invoked by either the VM thread (which will
1464     // serialize them) or by the GC workers while holding the
1465     // OldSets_lock.
1466     // (b) If we're not at a safepoint, operations on the master
1467     // humongous set should be invoked while holding the Heap_lock.
1468 
1469     if (SafepointSynchronize::is_at_safepoint()) {
1470       guarantee(Thread::current()->is_VM_thread() ||
1471                 OldSets_lock->owned_by_self(),
1472                 "master humongous set MT safety protocol at a safepoint");
1473     } else {
1474       guarantee(Heap_lock->owned_by_self(),
1475                 "master humongous set MT safety protocol outside a safepoint");
1476     }
1477   }
1478   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1479   const char* get_description() { return "Humongous Regions"; }
1480 };
1481 
1482 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1483   CollectedHeap(),
1484   _young_gen_sampling_thread(NULL),
1485   _workers(NULL),
1486   _collector_policy(collector_policy),
1487   _card_table(NULL),
1488   _soft_ref_policy(),
1489   _old_set("Old Region Set", new OldRegionSetChecker()),
1490   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1491   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1492   _bot(NULL),
1493   _listener(),
1494   _hrm(NULL),
1495   _allocator(NULL),
1496   _verifier(NULL),
1497   _summary_bytes_used(0),
1498   _archive_allocator(NULL),
1499   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1500   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1501   _expand_heap_after_alloc_failure(true),
1502   _g1mm(NULL),
1503   _humongous_reclaim_candidates(),
1504   _has_humongous_reclaim_candidates(false),
1505   _hr_printer(),
1506   _collector_state(),
1507   _old_marking_cycles_started(0),
1508   _old_marking_cycles_completed(0),
1509   _eden(),
1510   _survivor(),
1511   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1512   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1513   _policy(G1Policy::create_policy(collector_policy, _gc_timer_stw)),
1514   _heap_sizing_policy(NULL),
1515   _collection_set(this, _policy),
1516   _hot_card_cache(NULL),
1517   _rem_set(NULL),
1518   _dirty_card_queue_set(false),
1519   _cm(NULL),
1520   _cm_thread(NULL),
1521   _cr(NULL),
1522   _task_queues(NULL),
1523   _evacuation_failed(false),
1524   _evacuation_failed_info_array(NULL),
1525   _preserved_marks_set(true /* in_c_heap */),
1526 #ifndef PRODUCT
1527   _evacuation_failure_alot_for_current_gc(false),
1528   _evacuation_failure_alot_gc_number(0),
1529   _evacuation_failure_alot_count(0),
1530 #endif
1531   _ref_processor_stw(NULL),
1532   _is_alive_closure_stw(this),
1533   _is_subject_to_discovery_stw(this),
1534   _ref_processor_cm(NULL),
1535   _is_alive_closure_cm(this),
1536   _is_subject_to_discovery_cm(this),
1537   _in_cset_fast_test() {
1538 
1539   _verifier = new G1HeapVerifier(this);
1540 
1541   _allocator = new G1Allocator(this);
1542 
1543   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1544 
1545   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1546 
1547   // Override the default _filler_array_max_size so that no humongous filler
1548   // objects are created.
1549   _filler_array_max_size = _humongous_object_threshold_in_words;
1550 
1551   uint n_queues = ParallelGCThreads;
1552   _task_queues = new RefToScanQueueSet(n_queues);
1553 
1554   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1555 
1556   for (uint i = 0; i < n_queues; i++) {
1557     RefToScanQueue* q = new RefToScanQueue();
1558     q->initialize();
1559     _task_queues->register_queue(i, q);
1560     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1561   }
1562 
1563   // Initialize the G1EvacuationFailureALot counters and flags.
1564   NOT_PRODUCT(reset_evacuation_should_fail();)
1565 
1566   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1567 }
1568 
1569 static size_t actual_reserved_page_size(ReservedSpace rs) {
1570   size_t page_size = os::vm_page_size();
1571   if (UseLargePages) {
1572     // There are two ways to manage large page memory.
1573     // 1. OS supports committing large page memory.
1574     // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1575     //    And ReservedSpace calls it 'special'. If we failed to set 'special',
1576     //    we reserved memory without large page.
1577     if (os::can_commit_large_page_memory() || rs.special()) {
1578       // An alignment at ReservedSpace comes from preferred page size or
1579       // heap alignment, and if the alignment came from heap alignment, it could be
1580       // larger than large pages size. So need to cap with the large page size.
1581       page_size = MIN2(rs.alignment(), os::large_page_size());
1582     }
1583   }
1584 
1585   return page_size;
1586 }
1587 
1588 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1589                                                                  size_t size,
1590                                                                  size_t translation_factor) {
1591   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1592   // Allocate a new reserved space, preferring to use large pages.
1593   ReservedSpace rs(size, preferred_page_size);
1594   size_t page_size = actual_reserved_page_size(rs);
1595   G1RegionToSpaceMapper* result  =
1596     G1RegionToSpaceMapper::create_mapper(rs,
1597                                          size,
1598                                          page_size,
1599                                          HeapRegion::GrainBytes,
1600                                          translation_factor,
1601                                          mtGC);
1602 
1603   os::trace_page_sizes_for_requested_size(description,
1604                                           size,
1605                                           preferred_page_size,
1606                                           page_size,
1607                                           rs.base(),
1608                                           rs.size());
1609 
1610   return result;
1611 }
1612 
1613 jint G1CollectedHeap::initialize_concurrent_refinement() {
1614   jint ecode = JNI_OK;
1615   _cr = G1ConcurrentRefine::create(&ecode);
1616   return ecode;
1617 }
1618 
1619 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1620   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1621   if (_young_gen_sampling_thread->osthread() == NULL) {
1622     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1623     return JNI_ENOMEM;
1624   }
1625   return JNI_OK;
1626 }
1627 
1628 jint G1CollectedHeap::initialize() {
1629   os::enable_vtime();
1630 
1631   // Necessary to satisfy locking discipline assertions.
1632 
1633   MutexLocker x(Heap_lock);
1634 
1635   // While there are no constraints in the GC code that HeapWordSize
1636   // be any particular value, there are multiple other areas in the
1637   // system which believe this to be true (e.g. oop->object_size in some
1638   // cases incorrectly returns the size in wordSize units rather than
1639   // HeapWordSize).
1640   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1641 
1642   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1643   size_t max_byte_size = _collector_policy->heap_reserved_size_bytes();
1644   size_t heap_alignment = collector_policy()->heap_alignment();
1645 
1646   // Ensure that the sizes are properly aligned.
1647   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1648   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1649   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1650 
1651   // Reserve the maximum.
1652 
1653   // When compressed oops are enabled, the preferred heap base
1654   // is calculated by subtracting the requested size from the
1655   // 32Gb boundary and using the result as the base address for
1656   // heap reservation. If the requested size is not aligned to
1657   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1658   // into the ReservedHeapSpace constructor) then the actual
1659   // base of the reserved heap may end up differing from the
1660   // address that was requested (i.e. the preferred heap base).
1661   // If this happens then we could end up using a non-optimal
1662   // compressed oops mode.
1663 
1664   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1665                                                  heap_alignment);
1666 
1667   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1668 
1669   // Create the barrier set for the entire reserved region.
1670   G1CardTable* ct = new G1CardTable(reserved_region());
1671   ct->initialize();
1672   G1BarrierSet* bs = new G1BarrierSet(ct);
1673   bs->initialize();
1674   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1675   BarrierSet::set_barrier_set(bs);
1676   _card_table = ct;
1677 
1678   G1BarrierSet::satb_mark_queue_set().initialize(this,
1679                                                  SATB_Q_CBL_mon,
1680                                                  &bs->satb_mark_queue_buffer_allocator(),
1681                                                  G1SATBProcessCompletedThreshold,
1682                                                  G1SATBBufferEnqueueingThresholdPercent);
1683 
1684   // process_completed_buffers_threshold and max_completed_buffers are updated
1685   // later, based on the concurrent refinement object.
1686   G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1687                                                   &bs->dirty_card_queue_buffer_allocator(),
1688                                                   true); // init_free_ids
1689 
1690   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1691                                     &bs->dirty_card_queue_buffer_allocator());
1692 
1693   // Create the hot card cache.
1694   _hot_card_cache = new G1HotCardCache(this);
1695 
1696   // Carve out the G1 part of the heap.
1697   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1698   size_t page_size = actual_reserved_page_size(heap_rs);
1699   G1RegionToSpaceMapper* heap_storage =
1700     G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1701                                               g1_rs.size(),
1702                                               page_size,
1703                                               HeapRegion::GrainBytes,
1704                                               1,
1705                                               mtJavaHeap);
1706   if(heap_storage == NULL) {
1707     vm_shutdown_during_initialization("Could not initialize G1 heap");
1708     return JNI_ERR;
1709   }
1710 
1711   os::trace_page_sizes("Heap",
1712                        collector_policy()->min_heap_byte_size(),
1713                        max_byte_size,
1714                        page_size,
1715                        heap_rs.base(),
1716                        heap_rs.size());
1717   heap_storage->set_mapping_changed_listener(&_listener);
1718 
1719   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1720   G1RegionToSpaceMapper* bot_storage =
1721     create_aux_memory_mapper("Block Offset Table",
1722                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1723                              G1BlockOffsetTable::heap_map_factor());
1724 
1725   G1RegionToSpaceMapper* cardtable_storage =
1726     create_aux_memory_mapper("Card Table",
1727                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1728                              G1CardTable::heap_map_factor());
1729 
1730   G1RegionToSpaceMapper* card_counts_storage =
1731     create_aux_memory_mapper("Card Counts Table",
1732                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1733                              G1CardCounts::heap_map_factor());
1734 
1735   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1736   G1RegionToSpaceMapper* prev_bitmap_storage =
1737     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1738   G1RegionToSpaceMapper* next_bitmap_storage =
1739     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1740 
1741   _hrm = HeapRegionManager::create_manager(this, _collector_policy);
1742 
1743   _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1744   _card_table->initialize(cardtable_storage);
1745   // Do later initialization work for concurrent refinement.
1746   _hot_card_cache->initialize(card_counts_storage);
1747 
1748   // 6843694 - ensure that the maximum region index can fit
1749   // in the remembered set structures.
1750   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1751   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1752 
1753   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1754   // start within the first card.
1755   guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1756   // Also create a G1 rem set.
1757   _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1758   _rem_set->initialize(max_reserved_capacity(), max_regions());
1759 
1760   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1761   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1762   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1763             "too many cards per region");
1764 
1765   FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1766 
1767   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1768 
1769   {
1770     HeapWord* start = _hrm->reserved().start();
1771     HeapWord* end = _hrm->reserved().end();
1772     size_t granularity = HeapRegion::GrainBytes;
1773 
1774     _in_cset_fast_test.initialize(start, end, granularity);
1775     _humongous_reclaim_candidates.initialize(start, end, granularity);
1776   }
1777 
1778   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1779                           true /* are_GC_task_threads */,
1780                           false /* are_ConcurrentGC_threads */);
1781   if (_workers == NULL) {
1782     return JNI_ENOMEM;
1783   }
1784   _workers->initialize_workers();
1785 
1786   // Create the G1ConcurrentMark data structure and thread.
1787   // (Must do this late, so that "max_regions" is defined.)
1788   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1789   if (_cm == NULL || !_cm->completed_initialization()) {
1790     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1791     return JNI_ENOMEM;
1792   }
1793   _cm_thread = _cm->cm_thread();
1794 
1795   // Now expand into the initial heap size.
1796   if (!expand(init_byte_size, _workers)) {
1797     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1798     return JNI_ENOMEM;
1799   }
1800 
1801   // Perform any initialization actions delegated to the policy.
1802   policy()->init(this, &_collection_set);
1803 
1804   jint ecode = initialize_concurrent_refinement();
1805   if (ecode != JNI_OK) {
1806     return ecode;
1807   }
1808 
1809   ecode = initialize_young_gen_sampling_thread();
1810   if (ecode != JNI_OK) {
1811     return ecode;
1812   }
1813 
1814   {
1815     G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1816     dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone());
1817     dcqs.set_max_completed_buffers(concurrent_refine()->red_zone());
1818   }
1819 
1820   // Here we allocate the dummy HeapRegion that is required by the
1821   // G1AllocRegion class.
1822   HeapRegion* dummy_region = _hrm->get_dummy_region();
1823 
1824   // We'll re-use the same region whether the alloc region will
1825   // require BOT updates or not and, if it doesn't, then a non-young
1826   // region will complain that it cannot support allocations without
1827   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1828   dummy_region->set_eden();
1829   // Make sure it's full.
1830   dummy_region->set_top(dummy_region->end());
1831   G1AllocRegion::setup(this, dummy_region);
1832 
1833   _allocator->init_mutator_alloc_region();
1834 
1835   // Do create of the monitoring and management support so that
1836   // values in the heap have been properly initialized.
1837   _g1mm = new G1MonitoringSupport(this);
1838 
1839   G1StringDedup::initialize();
1840 
1841   _preserved_marks_set.init(ParallelGCThreads);
1842 
1843   _collection_set.initialize(max_regions());
1844 
1845   return JNI_OK;
1846 }
1847 
1848 void G1CollectedHeap::stop() {
1849   // Stop all concurrent threads. We do this to make sure these threads
1850   // do not continue to execute and access resources (e.g. logging)
1851   // that are destroyed during shutdown.
1852   _cr->stop();
1853   _young_gen_sampling_thread->stop();
1854   _cm_thread->stop();
1855   if (G1StringDedup::is_enabled()) {
1856     G1StringDedup::stop();
1857   }
1858 }
1859 
1860 void G1CollectedHeap::safepoint_synchronize_begin() {
1861   SuspendibleThreadSet::synchronize();
1862 }
1863 
1864 void G1CollectedHeap::safepoint_synchronize_end() {
1865   SuspendibleThreadSet::desynchronize();
1866 }
1867 
1868 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1869   return HeapRegion::max_region_size();
1870 }
1871 
1872 void G1CollectedHeap::post_initialize() {
1873   CollectedHeap::post_initialize();
1874   ref_processing_init();
1875 }
1876 
1877 void G1CollectedHeap::ref_processing_init() {
1878   // Reference processing in G1 currently works as follows:
1879   //
1880   // * There are two reference processor instances. One is
1881   //   used to record and process discovered references
1882   //   during concurrent marking; the other is used to
1883   //   record and process references during STW pauses
1884   //   (both full and incremental).
1885   // * Both ref processors need to 'span' the entire heap as
1886   //   the regions in the collection set may be dotted around.
1887   //
1888   // * For the concurrent marking ref processor:
1889   //   * Reference discovery is enabled at initial marking.
1890   //   * Reference discovery is disabled and the discovered
1891   //     references processed etc during remarking.
1892   //   * Reference discovery is MT (see below).
1893   //   * Reference discovery requires a barrier (see below).
1894   //   * Reference processing may or may not be MT
1895   //     (depending on the value of ParallelRefProcEnabled
1896   //     and ParallelGCThreads).
1897   //   * A full GC disables reference discovery by the CM
1898   //     ref processor and abandons any entries on it's
1899   //     discovered lists.
1900   //
1901   // * For the STW processor:
1902   //   * Non MT discovery is enabled at the start of a full GC.
1903   //   * Processing and enqueueing during a full GC is non-MT.
1904   //   * During a full GC, references are processed after marking.
1905   //
1906   //   * Discovery (may or may not be MT) is enabled at the start
1907   //     of an incremental evacuation pause.
1908   //   * References are processed near the end of a STW evacuation pause.
1909   //   * For both types of GC:
1910   //     * Discovery is atomic - i.e. not concurrent.
1911   //     * Reference discovery will not need a barrier.
1912 
1913   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1914 
1915   // Concurrent Mark ref processor
1916   _ref_processor_cm =
1917     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1918                            mt_processing,                                  // mt processing
1919                            ParallelGCThreads,                              // degree of mt processing
1920                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1921                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1922                            false,                                          // Reference discovery is not atomic
1923                            &_is_alive_closure_cm,                          // is alive closure
1924                            true);                                          // allow changes to number of processing threads
1925 
1926   // STW ref processor
1927   _ref_processor_stw =
1928     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1929                            mt_processing,                        // mt processing
1930                            ParallelGCThreads,                    // degree of mt processing
1931                            (ParallelGCThreads > 1),              // mt discovery
1932                            ParallelGCThreads,                    // degree of mt discovery
1933                            true,                                 // Reference discovery is atomic
1934                            &_is_alive_closure_stw,               // is alive closure
1935                            true);                                // allow changes to number of processing threads
1936 }
1937 
1938 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1939   return _collector_policy;
1940 }
1941 
1942 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1943   return &_soft_ref_policy;
1944 }
1945 
1946 size_t G1CollectedHeap::capacity() const {
1947   return _hrm->length() * HeapRegion::GrainBytes;
1948 }
1949 
1950 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1951   return _hrm->total_free_bytes();
1952 }
1953 
1954 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1955   _hot_card_cache->drain(cl, worker_i);
1956 }
1957 
1958 void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1959   G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1960   size_t n_completed_buffers = 0;
1961   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1962     n_completed_buffers++;
1963   }
1964   assert(dcqs.completed_buffers_num() == 0, "Completed buffers exist!");
1965   phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1966 }
1967 
1968 // Computes the sum of the storage used by the various regions.
1969 size_t G1CollectedHeap::used() const {
1970   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1971   if (_archive_allocator != NULL) {
1972     result += _archive_allocator->used();
1973   }
1974   return result;
1975 }
1976 
1977 size_t G1CollectedHeap::used_unlocked() const {
1978   return _summary_bytes_used;
1979 }
1980 
1981 class SumUsedClosure: public HeapRegionClosure {
1982   size_t _used;
1983 public:
1984   SumUsedClosure() : _used(0) {}
1985   bool do_heap_region(HeapRegion* r) {
1986     _used += r->used();
1987     return false;
1988   }
1989   size_t result() { return _used; }
1990 };
1991 
1992 size_t G1CollectedHeap::recalculate_used() const {
1993   SumUsedClosure blk;
1994   heap_region_iterate(&blk);
1995   return blk.result();
1996 }
1997 
1998 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1999   switch (cause) {
2000     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2001     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2002     case GCCause::_wb_conc_mark:                        return true;
2003     default :                                           return false;
2004   }
2005 }
2006 
2007 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2008   switch (cause) {
2009     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2010     case GCCause::_g1_humongous_allocation: return true;
2011     case GCCause::_g1_periodic_collection:  return G1PeriodicGCInvokesConcurrent;
2012     default:                                return is_user_requested_concurrent_full_gc(cause);
2013   }
2014 }
2015 
2016 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2017   if(policy()->force_upgrade_to_full()) {
2018     return true;
2019   } else if (should_do_concurrent_full_gc(_gc_cause)) {
2020     return false;
2021   } else if (has_regions_left_for_allocation()) {
2022     return false;
2023   } else {
2024     return true;
2025   }
2026 }
2027 
2028 #ifndef PRODUCT
2029 void G1CollectedHeap::allocate_dummy_regions() {
2030   // Let's fill up most of the region
2031   size_t word_size = HeapRegion::GrainWords - 1024;
2032   // And as a result the region we'll allocate will be humongous.
2033   guarantee(is_humongous(word_size), "sanity");
2034 
2035   // _filler_array_max_size is set to humongous object threshold
2036   // but temporarily change it to use CollectedHeap::fill_with_object().
2037   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2038 
2039   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2040     // Let's use the existing mechanism for the allocation
2041     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2042     if (dummy_obj != NULL) {
2043       MemRegion mr(dummy_obj, word_size);
2044       CollectedHeap::fill_with_object(mr);
2045     } else {
2046       // If we can't allocate once, we probably cannot allocate
2047       // again. Let's get out of the loop.
2048       break;
2049     }
2050   }
2051 }
2052 #endif // !PRODUCT
2053 
2054 void G1CollectedHeap::increment_old_marking_cycles_started() {
2055   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2056          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2057          "Wrong marking cycle count (started: %d, completed: %d)",
2058          _old_marking_cycles_started, _old_marking_cycles_completed);
2059 
2060   _old_marking_cycles_started++;
2061 }
2062 
2063 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2064   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2065 
2066   // We assume that if concurrent == true, then the caller is a
2067   // concurrent thread that was joined the Suspendible Thread
2068   // Set. If there's ever a cheap way to check this, we should add an
2069   // assert here.
2070 
2071   // Given that this method is called at the end of a Full GC or of a
2072   // concurrent cycle, and those can be nested (i.e., a Full GC can
2073   // interrupt a concurrent cycle), the number of full collections
2074   // completed should be either one (in the case where there was no
2075   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2076   // behind the number of full collections started.
2077 
2078   // This is the case for the inner caller, i.e. a Full GC.
2079   assert(concurrent ||
2080          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2081          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2082          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2083          "is inconsistent with _old_marking_cycles_completed = %u",
2084          _old_marking_cycles_started, _old_marking_cycles_completed);
2085 
2086   // This is the case for the outer caller, i.e. the concurrent cycle.
2087   assert(!concurrent ||
2088          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2089          "for outer caller (concurrent cycle): "
2090          "_old_marking_cycles_started = %u "
2091          "is inconsistent with _old_marking_cycles_completed = %u",
2092          _old_marking_cycles_started, _old_marking_cycles_completed);
2093 
2094   _old_marking_cycles_completed += 1;
2095 
2096   // We need to clear the "in_progress" flag in the CM thread before
2097   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2098   // is set) so that if a waiter requests another System.gc() it doesn't
2099   // incorrectly see that a marking cycle is still in progress.
2100   if (concurrent) {
2101     _cm_thread->set_idle();
2102   }
2103 
2104   // This notify_all() will ensure that a thread that called
2105   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2106   // and it's waiting for a full GC to finish will be woken up. It is
2107   // waiting in VM_G1CollectForAllocation::doit_epilogue().
2108   FullGCCount_lock->notify_all();
2109 }
2110 
2111 void G1CollectedHeap::collect(GCCause::Cause cause) {
2112   try_collect(cause, true);
2113 }
2114 
2115 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) {
2116   assert_heap_not_locked();
2117 
2118   bool gc_succeeded;
2119   bool should_retry_gc;
2120 
2121   do {
2122     should_retry_gc = false;
2123 
2124     uint gc_count_before;
2125     uint old_marking_count_before;
2126     uint full_gc_count_before;
2127 
2128     {
2129       MutexLocker ml(Heap_lock);
2130 
2131       // Read the GC count while holding the Heap_lock
2132       gc_count_before = total_collections();
2133       full_gc_count_before = total_full_collections();
2134       old_marking_count_before = _old_marking_cycles_started;
2135     }
2136 
2137     if (should_do_concurrent_full_gc(cause)) {
2138       // Schedule an initial-mark evacuation pause that will start a
2139       // concurrent cycle. We're setting word_size to 0 which means that
2140       // we are not requesting a post-GC allocation.
2141       VM_G1CollectForAllocation op(0,     /* word_size */
2142                                    gc_count_before,
2143                                    cause,
2144                                    true,  /* should_initiate_conc_mark */
2145                                    policy()->max_pause_time_ms());
2146       VMThread::execute(&op);
2147       gc_succeeded = op.gc_succeeded();
2148       if (!gc_succeeded && retry_on_gc_failure) {
2149         if (old_marking_count_before == _old_marking_cycles_started) {
2150           should_retry_gc = op.should_retry_gc();
2151         } else {
2152           // A Full GC happened while we were trying to schedule the
2153           // concurrent cycle. No point in starting a new cycle given
2154           // that the whole heap was collected anyway.
2155         }
2156 
2157         if (should_retry_gc && GCLocker::is_active_and_needs_gc()) {
2158           GCLocker::stall_until_clear();
2159         }
2160       }
2161     } else {
2162       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2163           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2164 
2165         // Schedule a standard evacuation pause. We're setting word_size
2166         // to 0 which means that we are not requesting a post-GC allocation.
2167         VM_G1CollectForAllocation op(0,     /* word_size */
2168                                      gc_count_before,
2169                                      cause,
2170                                      false, /* should_initiate_conc_mark */
2171                                      policy()->max_pause_time_ms());
2172         VMThread::execute(&op);
2173         gc_succeeded = op.gc_succeeded();
2174       } else {
2175         // Schedule a Full GC.
2176         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2177         VMThread::execute(&op);
2178         gc_succeeded = op.gc_succeeded();
2179       }
2180     }
2181   } while (should_retry_gc);
2182   return gc_succeeded;
2183 }
2184 
2185 bool G1CollectedHeap::is_in(const void* p) const {
2186   if (_hrm->reserved().contains(p)) {
2187     // Given that we know that p is in the reserved space,
2188     // heap_region_containing() should successfully
2189     // return the containing region.
2190     HeapRegion* hr = heap_region_containing(p);
2191     return hr->is_in(p);
2192   } else {
2193     return false;
2194   }
2195 }
2196 
2197 #ifdef ASSERT
2198 bool G1CollectedHeap::is_in_exact(const void* p) const {
2199   bool contains = reserved_region().contains(p);
2200   bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2201   if (contains && available) {
2202     return true;
2203   } else {
2204     return false;
2205   }
2206 }
2207 #endif
2208 
2209 // Iteration functions.
2210 
2211 // Iterates an ObjectClosure over all objects within a HeapRegion.
2212 
2213 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2214   ObjectClosure* _cl;
2215 public:
2216   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2217   bool do_heap_region(HeapRegion* r) {
2218     if (!r->is_continues_humongous()) {
2219       r->object_iterate(_cl);
2220     }
2221     return false;
2222   }
2223 };
2224 
2225 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2226   IterateObjectClosureRegionClosure blk(cl);
2227   heap_region_iterate(&blk);
2228 }
2229 
2230 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2231   _hrm->iterate(cl);
2232 }
2233 
2234 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2235                                                                  HeapRegionClaimer *hrclaimer,
2236                                                                  uint worker_id) const {
2237   _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2238 }
2239 
2240 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2241                                                          HeapRegionClaimer *hrclaimer) const {
2242   _hrm->par_iterate(cl, hrclaimer, 0);
2243 }
2244 
2245 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2246   _collection_set.iterate(cl);
2247 }
2248 
2249 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2250   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2251 }
2252 
2253 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2254   HeapRegion* hr = heap_region_containing(addr);
2255   return hr->block_start(addr);
2256 }
2257 
2258 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2259   HeapRegion* hr = heap_region_containing(addr);
2260   return hr->block_is_obj(addr);
2261 }
2262 
2263 bool G1CollectedHeap::supports_tlab_allocation() const {
2264   return true;
2265 }
2266 
2267 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2268   return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2269 }
2270 
2271 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2272   return _eden.length() * HeapRegion::GrainBytes;
2273 }
2274 
2275 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2276 // must be equal to the humongous object limit.
2277 size_t G1CollectedHeap::max_tlab_size() const {
2278   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2279 }
2280 
2281 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2282   return _allocator->unsafe_max_tlab_alloc();
2283 }
2284 
2285 size_t G1CollectedHeap::max_capacity() const {
2286   return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2287 }
2288 
2289 size_t G1CollectedHeap::max_reserved_capacity() const {
2290   return _hrm->max_length() * HeapRegion::GrainBytes;
2291 }
2292 
2293 jlong G1CollectedHeap::millis_since_last_gc() {
2294   // See the notes in GenCollectedHeap::millis_since_last_gc()
2295   // for more information about the implementation.
2296   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2297                   _policy->collection_pause_end_millis();
2298   if (ret_val < 0) {
2299     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2300       ". returning zero instead.", ret_val);
2301     return 0;
2302   }
2303   return ret_val;
2304 }
2305 
2306 void G1CollectedHeap::deduplicate_string(oop str) {
2307   assert(java_lang_String::is_instance(str), "invariant");
2308 
2309   if (G1StringDedup::is_enabled()) {
2310     G1StringDedup::deduplicate(str);
2311   }
2312 }
2313 
2314 void G1CollectedHeap::prepare_for_verify() {
2315   _verifier->prepare_for_verify();
2316 }
2317 
2318 void G1CollectedHeap::verify(VerifyOption vo) {
2319   _verifier->verify(vo);
2320 }
2321 
2322 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2323   return true;
2324 }
2325 
2326 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2327   return _cm_thread->request_concurrent_phase(phase);
2328 }
2329 
2330 bool G1CollectedHeap::is_heterogeneous_heap() const {
2331   return _collector_policy->is_heterogeneous_heap();
2332 }
2333 
2334 class PrintRegionClosure: public HeapRegionClosure {
2335   outputStream* _st;
2336 public:
2337   PrintRegionClosure(outputStream* st) : _st(st) {}
2338   bool do_heap_region(HeapRegion* r) {
2339     r->print_on(_st);
2340     return false;
2341   }
2342 };
2343 
2344 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2345                                        const HeapRegion* hr,
2346                                        const VerifyOption vo) const {
2347   switch (vo) {
2348   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2349   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2350   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2351   default:                            ShouldNotReachHere();
2352   }
2353   return false; // keep some compilers happy
2354 }
2355 
2356 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2357                                        const VerifyOption vo) const {
2358   switch (vo) {
2359   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2360   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2361   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2362   default:                            ShouldNotReachHere();
2363   }
2364   return false; // keep some compilers happy
2365 }
2366 
2367 void G1CollectedHeap::print_heap_regions() const {
2368   LogTarget(Trace, gc, heap, region) lt;
2369   if (lt.is_enabled()) {
2370     LogStream ls(lt);
2371     print_regions_on(&ls);
2372   }
2373 }
2374 
2375 void G1CollectedHeap::print_on(outputStream* st) const {
2376   st->print(" %-20s", "garbage-first heap");
2377   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2378             capacity()/K, used_unlocked()/K);
2379   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2380             p2i(_hrm->reserved().start()),
2381             p2i(_hrm->reserved().end()));
2382   st->cr();
2383   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2384   uint young_regions = young_regions_count();
2385   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2386             (size_t) young_regions * HeapRegion::GrainBytes / K);
2387   uint survivor_regions = survivor_regions_count();
2388   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2389             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2390   st->cr();
2391   MetaspaceUtils::print_on(st);
2392 }
2393 
2394 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2395   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2396                "HS=humongous(starts), HC=humongous(continues), "
2397                "CS=collection set, F=free, A=archive, "
2398                "TAMS=top-at-mark-start (previous, next)");
2399   PrintRegionClosure blk(st);
2400   heap_region_iterate(&blk);
2401 }
2402 
2403 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2404   print_on(st);
2405 
2406   // Print the per-region information.
2407   print_regions_on(st);
2408 }
2409 
2410 void G1CollectedHeap::print_on_error(outputStream* st) const {
2411   this->CollectedHeap::print_on_error(st);
2412 
2413   if (_cm != NULL) {
2414     st->cr();
2415     _cm->print_on_error(st);
2416   }
2417 }
2418 
2419 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2420   workers()->print_worker_threads_on(st);
2421   _cm_thread->print_on(st);
2422   st->cr();
2423   _cm->print_worker_threads_on(st);
2424   _cr->print_threads_on(st);
2425   _young_gen_sampling_thread->print_on(st);
2426   if (G1StringDedup::is_enabled()) {
2427     G1StringDedup::print_worker_threads_on(st);
2428   }
2429 }
2430 
2431 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2432   workers()->threads_do(tc);
2433   tc->do_thread(_cm_thread);
2434   _cm->threads_do(tc);
2435   _cr->threads_do(tc);
2436   tc->do_thread(_young_gen_sampling_thread);
2437   if (G1StringDedup::is_enabled()) {
2438     G1StringDedup::threads_do(tc);
2439   }
2440 }
2441 
2442 void G1CollectedHeap::print_tracing_info() const {
2443   rem_set()->print_summary_info();
2444   concurrent_mark()->print_summary_info();
2445 }
2446 
2447 #ifndef PRODUCT
2448 // Helpful for debugging RSet issues.
2449 
2450 class PrintRSetsClosure : public HeapRegionClosure {
2451 private:
2452   const char* _msg;
2453   size_t _occupied_sum;
2454 
2455 public:
2456   bool do_heap_region(HeapRegion* r) {
2457     HeapRegionRemSet* hrrs = r->rem_set();
2458     size_t occupied = hrrs->occupied();
2459     _occupied_sum += occupied;
2460 
2461     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2462     if (occupied == 0) {
2463       tty->print_cr("  RSet is empty");
2464     } else {
2465       hrrs->print();
2466     }
2467     tty->print_cr("----------");
2468     return false;
2469   }
2470 
2471   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2472     tty->cr();
2473     tty->print_cr("========================================");
2474     tty->print_cr("%s", msg);
2475     tty->cr();
2476   }
2477 
2478   ~PrintRSetsClosure() {
2479     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2480     tty->print_cr("========================================");
2481     tty->cr();
2482   }
2483 };
2484 
2485 void G1CollectedHeap::print_cset_rsets() {
2486   PrintRSetsClosure cl("Printing CSet RSets");
2487   collection_set_iterate(&cl);
2488 }
2489 
2490 void G1CollectedHeap::print_all_rsets() {
2491   PrintRSetsClosure cl("Printing All RSets");;
2492   heap_region_iterate(&cl);
2493 }
2494 #endif // PRODUCT
2495 
2496 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2497 
2498   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2499   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2500   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2501 
2502   size_t eden_capacity_bytes =
2503     (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2504 
2505   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2506   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2507                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2508 }
2509 
2510 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2511   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2512                        stats->unused(), stats->used(), stats->region_end_waste(),
2513                        stats->regions_filled(), stats->direct_allocated(),
2514                        stats->failure_used(), stats->failure_waste());
2515 }
2516 
2517 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2518   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2519   gc_tracer->report_gc_heap_summary(when, heap_summary);
2520 
2521   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2522   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2523 }
2524 
2525 G1CollectedHeap* G1CollectedHeap::heap() {
2526   CollectedHeap* heap = Universe::heap();
2527   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2528   assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2529   return (G1CollectedHeap*)heap;
2530 }
2531 
2532 void G1CollectedHeap::gc_prologue(bool full) {
2533   // always_do_update_barrier = false;
2534   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2535 
2536   // This summary needs to be printed before incrementing total collections.
2537   rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2538 
2539   // Update common counters.
2540   increment_total_collections(full /* full gc */);
2541   if (full || collector_state()->in_initial_mark_gc()) {
2542     increment_old_marking_cycles_started();
2543   }
2544 
2545   // Fill TLAB's and such
2546   double start = os::elapsedTime();
2547   ensure_parsability(true);
2548   phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2549 }
2550 
2551 void G1CollectedHeap::gc_epilogue(bool full) {
2552   // Update common counters.
2553   if (full) {
2554     // Update the number of full collections that have been completed.
2555     increment_old_marking_cycles_completed(false /* concurrent */);
2556   }
2557 
2558   // We are at the end of the GC. Total collections has already been increased.
2559   rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2560 
2561   // FIXME: what is this about?
2562   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2563   // is set.
2564 #if COMPILER2_OR_JVMCI
2565   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2566 #endif
2567   // always_do_update_barrier = true;
2568 
2569   double start = os::elapsedTime();
2570   resize_all_tlabs();
2571   phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2572 
2573   MemoryService::track_memory_usage();
2574   // We have just completed a GC. Update the soft reference
2575   // policy with the new heap occupancy
2576   Universe::update_heap_info_at_gc();
2577 }
2578 
2579 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2580                                                uint gc_count_before,
2581                                                bool* succeeded,
2582                                                GCCause::Cause gc_cause) {
2583   assert_heap_not_locked_and_not_at_safepoint();
2584   VM_G1CollectForAllocation op(word_size,
2585                                gc_count_before,
2586                                gc_cause,
2587                                false, /* should_initiate_conc_mark */
2588                                policy()->max_pause_time_ms());
2589   VMThread::execute(&op);
2590 
2591   HeapWord* result = op.result();
2592   bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2593   assert(result == NULL || ret_succeeded,
2594          "the result should be NULL if the VM did not succeed");
2595   *succeeded = ret_succeeded;
2596 
2597   assert_heap_not_locked();
2598   return result;
2599 }
2600 
2601 void G1CollectedHeap::do_concurrent_mark() {
2602   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2603   if (!_cm_thread->in_progress()) {
2604     _cm_thread->set_started();
2605     CGC_lock->notify();
2606   }
2607 }
2608 
2609 size_t G1CollectedHeap::pending_card_num() {
2610   struct CountCardsClosure : public ThreadClosure {
2611     size_t _cards;
2612     CountCardsClosure() : _cards(0) {}
2613     virtual void do_thread(Thread* t) {
2614       _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2615     }
2616   } count_from_threads;
2617   Threads::threads_do(&count_from_threads);
2618 
2619   G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2620   size_t buffer_size = dcqs.buffer_size();
2621   size_t buffer_num = dcqs.completed_buffers_num();
2622 
2623   return buffer_size * buffer_num + count_from_threads._cards;
2624 }
2625 
2626 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2627   // We don't nominate objects with many remembered set entries, on
2628   // the assumption that such objects are likely still live.
2629   HeapRegionRemSet* rem_set = r->rem_set();
2630 
2631   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2632          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2633          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2634 }
2635 
2636 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2637  private:
2638   size_t _total_humongous;
2639   size_t _candidate_humongous;
2640 
2641   G1DirtyCardQueue _dcq;
2642 
2643   bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2644     assert(region->is_starts_humongous(), "Must start a humongous object");
2645 
2646     oop obj = oop(region->bottom());
2647 
2648     // Dead objects cannot be eager reclaim candidates. Due to class
2649     // unloading it is unsafe to query their classes so we return early.
2650     if (g1h->is_obj_dead(obj, region)) {
2651       return false;
2652     }
2653 
2654     // If we do not have a complete remembered set for the region, then we can
2655     // not be sure that we have all references to it.
2656     if (!region->rem_set()->is_complete()) {
2657       return false;
2658     }
2659     // Candidate selection must satisfy the following constraints
2660     // while concurrent marking is in progress:
2661     //
2662     // * In order to maintain SATB invariants, an object must not be
2663     // reclaimed if it was allocated before the start of marking and
2664     // has not had its references scanned.  Such an object must have
2665     // its references (including type metadata) scanned to ensure no
2666     // live objects are missed by the marking process.  Objects
2667     // allocated after the start of concurrent marking don't need to
2668     // be scanned.
2669     //
2670     // * An object must not be reclaimed if it is on the concurrent
2671     // mark stack.  Objects allocated after the start of concurrent
2672     // marking are never pushed on the mark stack.
2673     //
2674     // Nominating only objects allocated after the start of concurrent
2675     // marking is sufficient to meet both constraints.  This may miss
2676     // some objects that satisfy the constraints, but the marking data
2677     // structures don't support efficiently performing the needed
2678     // additional tests or scrubbing of the mark stack.
2679     //
2680     // However, we presently only nominate is_typeArray() objects.
2681     // A humongous object containing references induces remembered
2682     // set entries on other regions.  In order to reclaim such an
2683     // object, those remembered sets would need to be cleaned up.
2684     //
2685     // We also treat is_typeArray() objects specially, allowing them
2686     // to be reclaimed even if allocated before the start of
2687     // concurrent mark.  For this we rely on mark stack insertion to
2688     // exclude is_typeArray() objects, preventing reclaiming an object
2689     // that is in the mark stack.  We also rely on the metadata for
2690     // such objects to be built-in and so ensured to be kept live.
2691     // Frequent allocation and drop of large binary blobs is an
2692     // important use case for eager reclaim, and this special handling
2693     // may reduce needed headroom.
2694 
2695     return obj->is_typeArray() &&
2696            g1h->is_potential_eager_reclaim_candidate(region);
2697   }
2698 
2699  public:
2700   RegisterHumongousWithInCSetFastTestClosure()
2701   : _total_humongous(0),
2702     _candidate_humongous(0),
2703     _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2704   }
2705 
2706   virtual bool do_heap_region(HeapRegion* r) {
2707     if (!r->is_starts_humongous()) {
2708       return false;
2709     }
2710     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2711 
2712     bool is_candidate = humongous_region_is_candidate(g1h, r);
2713     uint rindex = r->hrm_index();
2714     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2715     if (is_candidate) {
2716       _candidate_humongous++;
2717       g1h->register_humongous_region_with_cset(rindex);
2718       // Is_candidate already filters out humongous object with large remembered sets.
2719       // If we have a humongous object with a few remembered sets, we simply flush these
2720       // remembered set entries into the DCQS. That will result in automatic
2721       // re-evaluation of their remembered set entries during the following evacuation
2722       // phase.
2723       if (!r->rem_set()->is_empty()) {
2724         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2725                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2726         G1CardTable* ct = g1h->card_table();
2727         HeapRegionRemSetIterator hrrs(r->rem_set());
2728         size_t card_index;
2729         while (hrrs.has_next(card_index)) {
2730           CardTable::CardValue* card_ptr = ct->byte_for_index(card_index);
2731           // The remembered set might contain references to already freed
2732           // regions. Filter out such entries to avoid failing card table
2733           // verification.
2734           if (g1h->is_in(ct->addr_for(card_ptr))) {
2735             if (*card_ptr != G1CardTable::dirty_card_val()) {
2736               *card_ptr = G1CardTable::dirty_card_val();
2737               _dcq.enqueue(card_ptr);
2738             }
2739           }
2740         }
2741         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2742                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2743                hrrs.n_yielded(), r->rem_set()->occupied());
2744         // We should only clear the card based remembered set here as we will not
2745         // implicitly rebuild anything else during eager reclaim. Note that at the moment
2746         // (and probably never) we do not enter this path if there are other kind of
2747         // remembered sets for this region.
2748         r->rem_set()->clear_locked(true /* only_cardset */);
2749         // Clear_locked() above sets the state to Empty. However we want to continue
2750         // collecting remembered set entries for humongous regions that were not
2751         // reclaimed.
2752         r->rem_set()->set_state_complete();
2753       }
2754       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2755     }
2756     _total_humongous++;
2757 
2758     return false;
2759   }
2760 
2761   size_t total_humongous() const { return _total_humongous; }
2762   size_t candidate_humongous() const { return _candidate_humongous; }
2763 
2764   void flush_rem_set_entries() { _dcq.flush(); }
2765 };
2766 
2767 void G1CollectedHeap::register_humongous_regions_with_cset() {
2768   if (!G1EagerReclaimHumongousObjects) {
2769     phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2770     return;
2771   }
2772   double time = os::elapsed_counter();
2773 
2774   // Collect reclaim candidate information and register candidates with cset.
2775   RegisterHumongousWithInCSetFastTestClosure cl;
2776   heap_region_iterate(&cl);
2777 
2778   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2779   phase_times()->record_fast_reclaim_humongous_stats(time,
2780                                                      cl.total_humongous(),
2781                                                      cl.candidate_humongous());
2782   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2783 
2784   // Finally flush all remembered set entries to re-check into the global DCQS.
2785   cl.flush_rem_set_entries();
2786 }
2787 
2788 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2789   public:
2790     bool do_heap_region(HeapRegion* hr) {
2791       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2792         hr->verify_rem_set();
2793       }
2794       return false;
2795     }
2796 };
2797 
2798 uint G1CollectedHeap::num_task_queues() const {
2799   return _task_queues->size();
2800 }
2801 
2802 #if TASKQUEUE_STATS
2803 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2804   st->print_raw_cr("GC Task Stats");
2805   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2806   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2807 }
2808 
2809 void G1CollectedHeap::print_taskqueue_stats() const {
2810   if (!log_is_enabled(Trace, gc, task, stats)) {
2811     return;
2812   }
2813   Log(gc, task, stats) log;
2814   ResourceMark rm;
2815   LogStream ls(log.trace());
2816   outputStream* st = &ls;
2817 
2818   print_taskqueue_stats_hdr(st);
2819 
2820   TaskQueueStats totals;
2821   const uint n = num_task_queues();
2822   for (uint i = 0; i < n; ++i) {
2823     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2824     totals += task_queue(i)->stats;
2825   }
2826   st->print_raw("tot "); totals.print(st); st->cr();
2827 
2828   DEBUG_ONLY(totals.verify());
2829 }
2830 
2831 void G1CollectedHeap::reset_taskqueue_stats() {
2832   const uint n = num_task_queues();
2833   for (uint i = 0; i < n; ++i) {
2834     task_queue(i)->stats.reset();
2835   }
2836 }
2837 #endif // TASKQUEUE_STATS
2838 
2839 void G1CollectedHeap::wait_for_root_region_scanning() {
2840   double scan_wait_start = os::elapsedTime();
2841   // We have to wait until the CM threads finish scanning the
2842   // root regions as it's the only way to ensure that all the
2843   // objects on them have been correctly scanned before we start
2844   // moving them during the GC.
2845   bool waited = _cm->root_regions()->wait_until_scan_finished();
2846   double wait_time_ms = 0.0;
2847   if (waited) {
2848     double scan_wait_end = os::elapsedTime();
2849     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2850   }
2851   phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2852 }
2853 
2854 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2855 private:
2856   G1HRPrinter* _hr_printer;
2857 public:
2858   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2859 
2860   virtual bool do_heap_region(HeapRegion* r) {
2861     _hr_printer->cset(r);
2862     return false;
2863   }
2864 };
2865 
2866 void G1CollectedHeap::start_new_collection_set() {
2867   double start = os::elapsedTime();
2868 
2869   collection_set()->start_incremental_building();
2870 
2871   clear_cset_fast_test();
2872 
2873   guarantee(_eden.length() == 0, "eden should have been cleared");
2874   policy()->transfer_survivors_to_cset(survivor());
2875 
2876   // We redo the verification but now wrt to the new CSet which
2877   // has just got initialized after the previous CSet was freed.
2878   _cm->verify_no_collection_set_oops();
2879 
2880   phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2881 }
2882 
2883 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms){
2884   policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2885   evacuation_info.set_collectionset_regions(collection_set()->region_length());
2886 
2887   _cm->verify_no_collection_set_oops();
2888 
2889   if (_hr_printer.is_active()) {
2890     G1PrintCollectionSetClosure cl(&_hr_printer);
2891     _collection_set.iterate(&cl);
2892   }
2893 }
2894 
2895 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2896   if (collector_state()->in_initial_mark_gc()) {
2897     return G1HeapVerifier::G1VerifyConcurrentStart;
2898   } else if (collector_state()->in_young_only_phase()) {
2899     return G1HeapVerifier::G1VerifyYoungNormal;
2900   } else {
2901     return G1HeapVerifier::G1VerifyMixed;
2902   }
2903 }
2904 
2905 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2906   if (VerifyRememberedSets) {
2907     log_info(gc, verify)("[Verifying RemSets before GC]");
2908     VerifyRegionRemSetClosure v_cl;
2909     heap_region_iterate(&v_cl);
2910   }
2911   _verifier->verify_before_gc(type);
2912   _verifier->check_bitmaps("GC Start");
2913 }
2914 
2915 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2916   if (VerifyRememberedSets) {
2917     log_info(gc, verify)("[Verifying RemSets after GC]");
2918     VerifyRegionRemSetClosure v_cl;
2919     heap_region_iterate(&v_cl);
2920   }
2921   _verifier->verify_after_gc(type);
2922   _verifier->check_bitmaps("GC End");
2923 }
2924 
2925 void G1CollectedHeap::expand_heap_after_young_collection(){
2926   size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2927   if (expand_bytes > 0) {
2928     // No need for an ergo logging here,
2929     // expansion_amount() does this when it returns a value > 0.
2930     double expand_ms;
2931     if (!expand(expand_bytes, _workers, &expand_ms)) {
2932       // We failed to expand the heap. Cannot do anything about it.
2933     }
2934     phase_times()->record_expand_heap_time(expand_ms);
2935   }
2936 }
2937 
2938 const char* G1CollectedHeap::young_gc_name() const {
2939   if (collector_state()->in_initial_mark_gc()) {
2940     return "Pause Young (Concurrent Start)";
2941   } else if (collector_state()->in_young_only_phase()) {
2942     if (collector_state()->in_young_gc_before_mixed()) {
2943       return "Pause Young (Prepare Mixed)";
2944     } else {
2945       return "Pause Young (Normal)";
2946     }
2947   } else {
2948     return "Pause Young (Mixed)";
2949   }
2950 }
2951 
2952 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2953   assert_at_safepoint_on_vm_thread();
2954   guarantee(!is_gc_active(), "collection is not reentrant");
2955 
2956   if (GCLocker::check_active_before_gc()) {
2957     return false;
2958   }
2959 
2960   GCIdMark gc_id_mark;
2961 
2962   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2963   ResourceMark rm;
2964 
2965   policy()->note_gc_start();
2966 
2967   _gc_timer_stw->register_gc_start();
2968   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2969 
2970   wait_for_root_region_scanning();
2971 
2972   print_heap_before_gc();
2973   print_heap_regions();
2974   trace_heap_before_gc(_gc_tracer_stw);
2975 
2976   _verifier->verify_region_sets_optional();
2977   _verifier->verify_dirty_young_regions();
2978 
2979   // We should not be doing initial mark unless the conc mark thread is running
2980   if (!_cm_thread->should_terminate()) {
2981     // This call will decide whether this pause is an initial-mark
2982     // pause. If it is, in_initial_mark_gc() will return true
2983     // for the duration of this pause.
2984     policy()->decide_on_conc_mark_initiation();
2985   }
2986 
2987   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2988   assert(!collector_state()->in_initial_mark_gc() ||
2989          collector_state()->in_young_only_phase(), "sanity");
2990   // We also do not allow mixed GCs during marking.
2991   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2992 
2993   // Record whether this pause is an initial mark. When the current
2994   // thread has completed its logging output and it's safe to signal
2995   // the CM thread, the flag's value in the policy has been reset.
2996   bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2997   if (should_start_conc_mark) {
2998     _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2999   }
3000 
3001   // Inner scope for scope based logging, timers, and stats collection
3002   {
3003     G1EvacuationInfo evacuation_info;
3004 
3005     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3006 
3007     GCTraceCPUTime tcpu;
3008 
3009     GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3010 
3011     uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3012                                                             workers()->active_workers(),
3013                                                             Threads::number_of_non_daemon_threads());
3014     active_workers = workers()->update_active_workers(active_workers);
3015     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3016 
3017     G1MonitoringScope ms(g1mm(),
3018                          false /* full_gc */,
3019                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3020 
3021     G1HeapTransition heap_transition(this);
3022     size_t heap_used_bytes_before_gc = used();
3023 
3024     {
3025       IsGCActiveMark x;
3026 
3027       gc_prologue(false);
3028 
3029       G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3030       verify_before_young_collection(verify_type);
3031 
3032       {
3033         // The elapsed time induced by the start time below deliberately elides
3034         // the possible verification above.
3035         double sample_start_time_sec = os::elapsedTime();
3036 
3037         // Please see comment in g1CollectedHeap.hpp and
3038         // G1CollectedHeap::ref_processing_init() to see how
3039         // reference processing currently works in G1.
3040         _ref_processor_stw->enable_discovery();
3041 
3042         // We want to temporarily turn off discovery by the
3043         // CM ref processor, if necessary, and turn it back on
3044         // on again later if we do. Using a scoped
3045         // NoRefDiscovery object will do this.
3046         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3047 
3048         policy()->record_collection_pause_start(sample_start_time_sec);
3049 
3050         // Forget the current allocation region (we might even choose it to be part
3051         // of the collection set!).
3052         _allocator->release_mutator_alloc_region();
3053 
3054         calculate_collection_set(evacuation_info, target_pause_time_ms);
3055 
3056         G1ParScanThreadStateSet per_thread_states(this,
3057                                                   workers()->active_workers(),
3058                                                   collection_set()->young_region_length(),
3059                                                   collection_set()->optional_region_length());
3060         pre_evacuate_collection_set(evacuation_info);
3061 
3062         // Actually do the work...
3063         evacuate_collection_set(&per_thread_states);
3064         evacuate_optional_collection_set(&per_thread_states);
3065 
3066         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3067 
3068         start_new_collection_set();
3069 
3070         _survivor_evac_stats.adjust_desired_plab_sz();
3071         _old_evac_stats.adjust_desired_plab_sz();
3072 
3073         if (should_start_conc_mark) {
3074           // We have to do this before we notify the CM threads that
3075           // they can start working to make sure that all the
3076           // appropriate initialization is done on the CM object.
3077           concurrent_mark()->post_initial_mark();
3078           // Note that we don't actually trigger the CM thread at
3079           // this point. We do that later when we're sure that
3080           // the current thread has completed its logging output.
3081         }
3082 
3083         allocate_dummy_regions();
3084 
3085         _allocator->init_mutator_alloc_region();
3086 
3087         expand_heap_after_young_collection();
3088 
3089         double sample_end_time_sec = os::elapsedTime();
3090         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3091         size_t total_cards_scanned = phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3092         policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3093       }
3094 
3095       verify_after_young_collection(verify_type);
3096 
3097 #ifdef TRACESPINNING
3098       ParallelTaskTerminator::print_termination_counts();
3099 #endif
3100 
3101       gc_epilogue(false);
3102     }
3103 
3104     // Print the remainder of the GC log output.
3105     if (evacuation_failed()) {
3106       log_info(gc)("To-space exhausted");
3107     }
3108 
3109     policy()->print_phases();
3110     heap_transition.print();
3111 
3112     _hrm->verify_optional();
3113     _verifier->verify_region_sets_optional();
3114 
3115     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3116     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3117 
3118     print_heap_after_gc();
3119     print_heap_regions();
3120     trace_heap_after_gc(_gc_tracer_stw);
3121 
3122     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3123     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3124     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3125     // before any GC notifications are raised.
3126     g1mm()->update_sizes();
3127 
3128     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3129     _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3130     _gc_timer_stw->register_gc_end();
3131     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3132   }
3133   // It should now be safe to tell the concurrent mark thread to start
3134   // without its logging output interfering with the logging output
3135   // that came from the pause.
3136 
3137   if (should_start_conc_mark) {
3138     // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3139     // thread(s) could be running concurrently with us. Make sure that anything
3140     // after this point does not assume that we are the only GC thread running.
3141     // Note: of course, the actual marking work will not start until the safepoint
3142     // itself is released in SuspendibleThreadSet::desynchronize().
3143     do_concurrent_mark();
3144   }
3145 
3146   return true;
3147 }
3148 
3149 void G1CollectedHeap::remove_self_forwarding_pointers() {
3150   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3151   workers()->run_task(&rsfp_task);
3152 }
3153 
3154 void G1CollectedHeap::restore_after_evac_failure() {
3155   double remove_self_forwards_start = os::elapsedTime();
3156 
3157   remove_self_forwarding_pointers();
3158   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3159   _preserved_marks_set.restore(&task_executor);
3160 
3161   phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3162 }
3163 
3164 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3165   if (!_evacuation_failed) {
3166     _evacuation_failed = true;
3167   }
3168 
3169   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3170   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3171 }
3172 
3173 bool G1ParEvacuateFollowersClosure::offer_termination() {
3174   EventGCPhaseParallel event;
3175   G1ParScanThreadState* const pss = par_scan_state();
3176   start_term_time();
3177   const bool res = terminator()->offer_termination();
3178   end_term_time();
3179   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3180   return res;
3181 }
3182 
3183 void G1ParEvacuateFollowersClosure::do_void() {
3184   EventGCPhaseParallel event;
3185   G1ParScanThreadState* const pss = par_scan_state();
3186   pss->trim_queue();
3187   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3188   do {
3189     EventGCPhaseParallel event;
3190     pss->steal_and_trim_queue(queues());
3191     event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3192   } while (!offer_termination());
3193 }
3194 
3195 class G1ParTask : public AbstractGangTask {
3196 protected:
3197   G1CollectedHeap*         _g1h;
3198   G1ParScanThreadStateSet* _pss;
3199   RefToScanQueueSet*       _queues;
3200   G1RootProcessor*         _root_processor;
3201   TaskTerminator           _terminator;
3202   uint                     _n_workers;
3203 
3204 public:
3205   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3206     : AbstractGangTask("G1 collection"),
3207       _g1h(g1h),
3208       _pss(per_thread_states),
3209       _queues(task_queues),
3210       _root_processor(root_processor),
3211       _terminator(n_workers, _queues),
3212       _n_workers(n_workers)
3213   {}
3214 
3215   void work(uint worker_id) {
3216     if (worker_id >= _n_workers) return;  // no work needed this round
3217 
3218     double start_sec = os::elapsedTime();
3219     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3220 
3221     {
3222       ResourceMark rm;
3223       HandleMark   hm;
3224 
3225       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3226 
3227       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3228       pss->set_ref_discoverer(rp);
3229 
3230       double start_strong_roots_sec = os::elapsedTime();
3231 
3232       _root_processor->evacuate_roots(pss, worker_id);
3233 
3234       _g1h->rem_set()->oops_into_collection_set_do(pss, worker_id);
3235 
3236       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3237 
3238       double term_sec = 0.0;
3239       size_t evac_term_attempts = 0;
3240       {
3241         double start = os::elapsedTime();
3242         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, _terminator.terminator(), G1GCPhaseTimes::ObjCopy);
3243         evac.do_void();
3244 
3245         evac_term_attempts = evac.term_attempts();
3246         term_sec = evac.term_time();
3247         double elapsed_sec = os::elapsedTime() - start;
3248 
3249         G1GCPhaseTimes* p = _g1h->phase_times();
3250         p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3251 
3252         p->record_or_add_thread_work_item(G1GCPhaseTimes::ObjCopy,
3253                                           worker_id,
3254                                           pss->lab_waste_words() * HeapWordSize,
3255                                           G1GCPhaseTimes::ObjCopyLABWaste);
3256         p->record_or_add_thread_work_item(G1GCPhaseTimes::ObjCopy,
3257                                           worker_id,
3258                                           pss->lab_undo_waste_words() * HeapWordSize,
3259                                           G1GCPhaseTimes::ObjCopyLABUndoWaste);
3260 
3261         p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3262         p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3263       }
3264 
3265       assert(pss->queue_is_empty(), "should be empty");
3266 
3267       // Close the inner scope so that the ResourceMark and HandleMark
3268       // destructors are executed here and are included as part of the
3269       // "GC Worker Time".
3270     }
3271     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3272   }
3273 };
3274 
3275 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3276                                         bool class_unloading_occurred) {
3277   uint num_workers = workers()->active_workers();
3278   ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3279   workers()->run_task(&unlink_task);
3280 }
3281 
3282 // Clean string dedup data structures.
3283 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3284 // record the durations of the phases. Hence the almost-copy.
3285 class G1StringDedupCleaningTask : public AbstractGangTask {
3286   BoolObjectClosure* _is_alive;
3287   OopClosure* _keep_alive;
3288   G1GCPhaseTimes* _phase_times;
3289 
3290 public:
3291   G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3292                             OopClosure* keep_alive,
3293                             G1GCPhaseTimes* phase_times) :
3294     AbstractGangTask("Partial Cleaning Task"),
3295     _is_alive(is_alive),
3296     _keep_alive(keep_alive),
3297     _phase_times(phase_times)
3298   {
3299     assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3300     StringDedup::gc_prologue(true);
3301   }
3302 
3303   ~G1StringDedupCleaningTask() {
3304     StringDedup::gc_epilogue();
3305   }
3306 
3307   void work(uint worker_id) {
3308     StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3309     {
3310       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3311       StringDedupQueue::unlink_or_oops_do(&cl);
3312     }
3313     {
3314       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3315       StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3316     }
3317   }
3318 };
3319 
3320 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3321                                             OopClosure* keep_alive,
3322                                             G1GCPhaseTimes* phase_times) {
3323   G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3324   workers()->run_task(&cl);
3325 }
3326 
3327 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3328  private:
3329   G1DirtyCardQueueSet* _queue;
3330   G1CollectedHeap* _g1h;
3331  public:
3332   G1RedirtyLoggedCardsTask(G1DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3333     _queue(queue), _g1h(g1h) { }
3334 
3335   virtual void work(uint worker_id) {
3336     G1GCPhaseTimes* p = _g1h->phase_times();
3337     G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3338 
3339     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3340     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3341 
3342     p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3343   }
3344 };
3345 
3346 void G1CollectedHeap::redirty_logged_cards() {
3347   double redirty_logged_cards_start = os::elapsedTime();
3348 
3349   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3350   dirty_card_queue_set().reset_for_par_iteration();
3351   workers()->run_task(&redirty_task);
3352 
3353   G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3354   dcq.merge_bufferlists(&dirty_card_queue_set());
3355   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3356 
3357   phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3358 }
3359 
3360 // Weak Reference Processing support
3361 
3362 bool G1STWIsAliveClosure::do_object_b(oop p) {
3363   // An object is reachable if it is outside the collection set,
3364   // or is inside and copied.
3365   return !_g1h->is_in_cset(p) || p->is_forwarded();
3366 }
3367 
3368 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3369   assert(obj != NULL, "must not be NULL");
3370   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3371   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3372   // may falsely indicate that this is not the case here: however the collection set only
3373   // contains old regions when concurrent mark is not running.
3374   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3375 }
3376 
3377 // Non Copying Keep Alive closure
3378 class G1KeepAliveClosure: public OopClosure {
3379   G1CollectedHeap*_g1h;
3380 public:
3381   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3382   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3383   void do_oop(oop* p) {
3384     oop obj = *p;
3385     assert(obj != NULL, "the caller should have filtered out NULL values");
3386 
3387     const InCSetState cset_state =_g1h->in_cset_state(obj);
3388     if (!cset_state.is_in_cset_or_humongous()) {
3389       return;
3390     }
3391     if (cset_state.is_in_cset()) {
3392       assert( obj->is_forwarded(), "invariant" );
3393       *p = obj->forwardee();
3394     } else {
3395       assert(!obj->is_forwarded(), "invariant" );
3396       assert(cset_state.is_humongous(),
3397              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3398      _g1h->set_humongous_is_live(obj);
3399     }
3400   }
3401 };
3402 
3403 // Copying Keep Alive closure - can be called from both
3404 // serial and parallel code as long as different worker
3405 // threads utilize different G1ParScanThreadState instances
3406 // and different queues.
3407 
3408 class G1CopyingKeepAliveClosure: public OopClosure {
3409   G1CollectedHeap*         _g1h;
3410   G1ParScanThreadState*    _par_scan_state;
3411 
3412 public:
3413   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3414                             G1ParScanThreadState* pss):
3415     _g1h(g1h),
3416     _par_scan_state(pss)
3417   {}
3418 
3419   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3420   virtual void do_oop(      oop* p) { do_oop_work(p); }
3421 
3422   template <class T> void do_oop_work(T* p) {
3423     oop obj = RawAccess<>::oop_load(p);
3424 
3425     if (_g1h->is_in_cset_or_humongous(obj)) {
3426       // If the referent object has been forwarded (either copied
3427       // to a new location or to itself in the event of an
3428       // evacuation failure) then we need to update the reference
3429       // field and, if both reference and referent are in the G1
3430       // heap, update the RSet for the referent.
3431       //
3432       // If the referent has not been forwarded then we have to keep
3433       // it alive by policy. Therefore we have copy the referent.
3434       //
3435       // When the queue is drained (after each phase of reference processing)
3436       // the object and it's followers will be copied, the reference field set
3437       // to point to the new location, and the RSet updated.
3438       _par_scan_state->push_on_queue(p);
3439     }
3440   }
3441 };
3442 
3443 // Serial drain queue closure. Called as the 'complete_gc'
3444 // closure for each discovered list in some of the
3445 // reference processing phases.
3446 
3447 class G1STWDrainQueueClosure: public VoidClosure {
3448 protected:
3449   G1CollectedHeap* _g1h;
3450   G1ParScanThreadState* _par_scan_state;
3451 
3452   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3453 
3454 public:
3455   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3456     _g1h(g1h),
3457     _par_scan_state(pss)
3458   { }
3459 
3460   void do_void() {
3461     G1ParScanThreadState* const pss = par_scan_state();
3462     pss->trim_queue();
3463   }
3464 };
3465 
3466 // Parallel Reference Processing closures
3467 
3468 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3469 // processing during G1 evacuation pauses.
3470 
3471 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3472 private:
3473   G1CollectedHeap*          _g1h;
3474   G1ParScanThreadStateSet*  _pss;
3475   RefToScanQueueSet*        _queues;
3476   WorkGang*                 _workers;
3477 
3478 public:
3479   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3480                            G1ParScanThreadStateSet* per_thread_states,
3481                            WorkGang* workers,
3482                            RefToScanQueueSet *task_queues) :
3483     _g1h(g1h),
3484     _pss(per_thread_states),
3485     _queues(task_queues),
3486     _workers(workers)
3487   {
3488     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3489   }
3490 
3491   // Executes the given task using concurrent marking worker threads.
3492   virtual void execute(ProcessTask& task, uint ergo_workers);
3493 };
3494 
3495 // Gang task for possibly parallel reference processing
3496 
3497 class G1STWRefProcTaskProxy: public AbstractGangTask {
3498   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3499   ProcessTask&     _proc_task;
3500   G1CollectedHeap* _g1h;
3501   G1ParScanThreadStateSet* _pss;
3502   RefToScanQueueSet* _task_queues;
3503   ParallelTaskTerminator* _terminator;
3504 
3505 public:
3506   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3507                         G1CollectedHeap* g1h,
3508                         G1ParScanThreadStateSet* per_thread_states,
3509                         RefToScanQueueSet *task_queues,
3510                         ParallelTaskTerminator* terminator) :
3511     AbstractGangTask("Process reference objects in parallel"),
3512     _proc_task(proc_task),
3513     _g1h(g1h),
3514     _pss(per_thread_states),
3515     _task_queues(task_queues),
3516     _terminator(terminator)
3517   {}
3518 
3519   virtual void work(uint worker_id) {
3520     // The reference processing task executed by a single worker.
3521     ResourceMark rm;
3522     HandleMark   hm;
3523 
3524     G1STWIsAliveClosure is_alive(_g1h);
3525 
3526     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3527     pss->set_ref_discoverer(NULL);
3528 
3529     // Keep alive closure.
3530     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3531 
3532     // Complete GC closure
3533     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3534 
3535     // Call the reference processing task's work routine.
3536     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3537 
3538     // Note we cannot assert that the refs array is empty here as not all
3539     // of the processing tasks (specifically phase2 - pp2_work) execute
3540     // the complete_gc closure (which ordinarily would drain the queue) so
3541     // the queue may not be empty.
3542   }
3543 };
3544 
3545 // Driver routine for parallel reference processing.
3546 // Creates an instance of the ref processing gang
3547 // task and has the worker threads execute it.
3548 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3549   assert(_workers != NULL, "Need parallel worker threads.");
3550 
3551   assert(_workers->active_workers() >= ergo_workers,
3552          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3553          ergo_workers, _workers->active_workers());
3554   TaskTerminator terminator(ergo_workers, _queues);
3555   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3556 
3557   _workers->run_task(&proc_task_proxy, ergo_workers);
3558 }
3559 
3560 // End of weak reference support closures
3561 
3562 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3563   double ref_proc_start = os::elapsedTime();
3564 
3565   ReferenceProcessor* rp = _ref_processor_stw;
3566   assert(rp->discovery_enabled(), "should have been enabled");
3567 
3568   // Closure to test whether a referent is alive.
3569   G1STWIsAliveClosure is_alive(this);
3570 
3571   // Even when parallel reference processing is enabled, the processing
3572   // of JNI refs is serial and performed serially by the current thread
3573   // rather than by a worker. The following PSS will be used for processing
3574   // JNI refs.
3575 
3576   // Use only a single queue for this PSS.
3577   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3578   pss->set_ref_discoverer(NULL);
3579   assert(pss->queue_is_empty(), "pre-condition");
3580 
3581   // Keep alive closure.
3582   G1CopyingKeepAliveClosure keep_alive(this, pss);
3583 
3584   // Serial Complete GC closure
3585   G1STWDrainQueueClosure drain_queue(this, pss);
3586 
3587   // Setup the soft refs policy...
3588   rp->setup_policy(false);
3589 
3590   ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3591 
3592   ReferenceProcessorStats stats;
3593   if (!rp->processing_is_mt()) {
3594     // Serial reference processing...
3595     stats = rp->process_discovered_references(&is_alive,
3596                                               &keep_alive,
3597                                               &drain_queue,
3598                                               NULL,
3599                                               pt);
3600   } else {
3601     uint no_of_gc_workers = workers()->active_workers();
3602 
3603     // Parallel reference processing
3604     assert(no_of_gc_workers <= rp->max_num_queues(),
3605            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3606            no_of_gc_workers,  rp->max_num_queues());
3607 
3608     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3609     stats = rp->process_discovered_references(&is_alive,
3610                                               &keep_alive,
3611                                               &drain_queue,
3612                                               &par_task_executor,
3613                                               pt);
3614   }
3615 
3616   _gc_tracer_stw->report_gc_reference_stats(stats);
3617 
3618   // We have completed copying any necessary live referent objects.
3619   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3620 
3621   make_pending_list_reachable();
3622 
3623   assert(!rp->discovery_enabled(), "Postcondition");
3624   rp->verify_no_references_recorded();
3625 
3626   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3627   phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3628 }
3629 
3630 void G1CollectedHeap::make_pending_list_reachable() {
3631   if (collector_state()->in_initial_mark_gc()) {
3632     oop pll_head = Universe::reference_pending_list();
3633     if (pll_head != NULL) {
3634       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3635       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3636     }
3637   }
3638 }
3639 
3640 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3641   double merge_pss_time_start = os::elapsedTime();
3642   per_thread_states->flush();
3643   phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3644 }
3645 
3646 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info) {
3647   _expand_heap_after_alloc_failure = true;
3648   _evacuation_failed = false;
3649 
3650   // Disable the hot card cache.
3651   _hot_card_cache->reset_hot_cache_claimed_index();
3652   _hot_card_cache->set_use_cache(false);
3653 
3654   // Initialize the GC alloc regions.
3655   _allocator->init_gc_alloc_regions(evacuation_info);
3656 
3657   register_humongous_regions_with_cset();
3658   assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3659 
3660   rem_set()->prepare_for_oops_into_collection_set_do();
3661   _preserved_marks_set.assert_empty();
3662 
3663 #if COMPILER2_OR_JVMCI
3664   DerivedPointerTable::clear();
3665 #endif
3666 
3667   // InitialMark needs claim bits to keep track of the marked-through CLDs.
3668   if (collector_state()->in_initial_mark_gc()) {
3669     concurrent_mark()->pre_initial_mark();
3670 
3671     double start_clear_claimed_marks = os::elapsedTime();
3672 
3673     ClassLoaderDataGraph::clear_claimed_marks();
3674 
3675     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3676     phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3677   }
3678 }
3679 
3680 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3681   // Should G1EvacuationFailureALot be in effect for this GC?
3682   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3683 
3684   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3685 
3686   double start_par_time_sec = os::elapsedTime();
3687   double end_par_time_sec;
3688 
3689   {
3690     const uint n_workers = workers()->active_workers();
3691     G1RootProcessor root_processor(this, n_workers);
3692     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3693 
3694     workers()->run_task(&g1_par_task);
3695     end_par_time_sec = os::elapsedTime();
3696 
3697     // Closing the inner scope will execute the destructor
3698     // for the G1RootProcessor object. We record the current
3699     // elapsed time before closing the scope so that time
3700     // taken for the destructor is NOT included in the
3701     // reported parallel time.
3702   }
3703 
3704   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3705   phase_times()->record_par_time(par_time_ms);
3706 
3707   double code_root_fixup_time_ms =
3708         (os::elapsedTime() - end_par_time_sec) * 1000.0;
3709   phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
3710 }
3711 
3712 class G1EvacuateOptionalRegionTask : public AbstractGangTask {
3713   G1CollectedHeap* _g1h;
3714   G1ParScanThreadStateSet* _per_thread_states;
3715   G1OptionalCSet* _optional;
3716   RefToScanQueueSet* _queues;
3717   ParallelTaskTerminator _terminator;
3718 
3719   Tickspan trim_ticks(G1ParScanThreadState* pss) {
3720     Tickspan copy_time = pss->trim_ticks();
3721     pss->reset_trim_ticks();
3722     return copy_time;
3723   }
3724 
3725   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3726     G1EvacuationRootClosures* root_cls = pss->closures();
3727     G1ScanObjsDuringScanRSClosure obj_cl(_g1h, pss);
3728 
3729     size_t scanned = 0;
3730     size_t claimed = 0;
3731     size_t skipped = 0;
3732     size_t used_memory = 0;
3733 
3734     Ticks    start = Ticks::now();
3735     Tickspan copy_time;
3736 
3737     for (uint i = _optional->current_index(); i < _optional->current_limit(); i++) {
3738       HeapRegion* hr = _optional->region_at(i);
3739       G1ScanRSForOptionalClosure scan_opt_cl(&obj_cl);
3740       pss->oops_into_optional_region(hr)->oops_do(&scan_opt_cl, root_cls->raw_strong_oops());
3741       copy_time += trim_ticks(pss);
3742 
3743       G1ScanRSForRegionClosure scan_rs_cl(_g1h->rem_set()->scan_state(), &obj_cl, pss, G1GCPhaseTimes::OptScanRS, worker_id);
3744       scan_rs_cl.do_heap_region(hr);
3745       copy_time += trim_ticks(pss);
3746       scanned += scan_rs_cl.cards_scanned();
3747       claimed += scan_rs_cl.cards_claimed();
3748       skipped += scan_rs_cl.cards_skipped();
3749 
3750       // Chunk lists for this region is no longer needed.
3751       used_memory += pss->oops_into_optional_region(hr)->used_memory();
3752     }
3753 
3754     Tickspan scan_time = (Ticks::now() - start) - copy_time;
3755     G1GCPhaseTimes* p = _g1h->phase_times();
3756     p->record_or_add_time_secs(G1GCPhaseTimes::OptScanRS, worker_id, scan_time.seconds());
3757     p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, copy_time.seconds());
3758 
3759     p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, scanned, G1GCPhaseTimes::OptCSetScannedCards);
3760     p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, claimed, G1GCPhaseTimes::OptCSetClaimedCards);
3761     p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, skipped, G1GCPhaseTimes::OptCSetSkippedCards);
3762     p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, used_memory, G1GCPhaseTimes::OptCSetUsedMemory);
3763   }
3764 
3765   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3766     Ticks start = Ticks::now();
3767     G1ParEvacuateFollowersClosure cl(_g1h, pss, _queues, &_terminator, G1GCPhaseTimes::OptObjCopy);
3768     cl.do_void();
3769 
3770     Tickspan evac_time = (Ticks::now() - start);
3771     G1GCPhaseTimes* p = _g1h->phase_times();
3772     p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, evac_time.seconds());
3773     assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming done during optional evacuation");
3774   }
3775 
3776  public:
3777   G1EvacuateOptionalRegionTask(G1CollectedHeap* g1h,
3778                                G1ParScanThreadStateSet* per_thread_states,
3779                                G1OptionalCSet* cset,
3780                                RefToScanQueueSet* queues,
3781                                uint n_workers) :
3782     AbstractGangTask("G1 Evacuation Optional Region Task"),
3783     _g1h(g1h),
3784     _per_thread_states(per_thread_states),
3785     _optional(cset),
3786     _queues(queues),
3787     _terminator(n_workers, _queues) {
3788   }
3789 
3790   void work(uint worker_id) {
3791     ResourceMark rm;
3792     HandleMark  hm;
3793 
3794     G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3795     pss->set_ref_discoverer(_g1h->ref_processor_stw());
3796 
3797     scan_roots(pss, worker_id);
3798     evacuate_live_objects(pss, worker_id);
3799   }
3800 };
3801 
3802 void G1CollectedHeap::evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset) {
3803   class G1MarkScope : public MarkScope {};
3804   G1MarkScope code_mark_scope;
3805 
3806   G1EvacuateOptionalRegionTask task(this, per_thread_states, ocset, _task_queues, workers()->active_workers());
3807   workers()->run_task(&task);
3808 }
3809 
3810 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3811   G1OptionalCSet optional_cset(&_collection_set, per_thread_states);
3812   if (optional_cset.is_empty()) {
3813     return;
3814   }
3815 
3816   if (evacuation_failed()) {
3817     return;
3818   }
3819 
3820   const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3821 
3822   double start_time_sec = os::elapsedTime();
3823 
3824   do {
3825     double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3826     double time_left_ms = MaxGCPauseMillis - time_used_ms;
3827 
3828     if (time_left_ms < 0) {
3829       log_trace(gc, ergo, cset)("Skipping %u optional regions, pause time exceeded %.3fms", optional_cset.size(), time_used_ms);
3830       break;
3831     }
3832 
3833     optional_cset.prepare_evacuation(time_left_ms * _policy->optional_evacuation_fraction());
3834     if (optional_cset.prepare_failed()) {
3835       log_trace(gc, ergo, cset)("Skipping %u optional regions, no regions can be evacuated in %.3fms", optional_cset.size(), time_left_ms);
3836       break;
3837     }
3838 
3839     evacuate_optional_regions(per_thread_states, &optional_cset);
3840 
3841     optional_cset.complete_evacuation();
3842     if (optional_cset.evacuation_failed()) {
3843       break;
3844     }
3845   } while (!optional_cset.is_empty());
3846 
3847   phase_times()->record_optional_evacuation((os::elapsedTime() - start_time_sec) * 1000.0);
3848 }
3849 
3850 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3851   // Also cleans the card table from temporary duplicate detection information used
3852   // during UpdateRS/ScanRS.
3853   rem_set()->cleanup_after_oops_into_collection_set_do();
3854 
3855   // Process any discovered reference objects - we have
3856   // to do this _before_ we retire the GC alloc regions
3857   // as we may have to copy some 'reachable' referent
3858   // objects (and their reachable sub-graphs) that were
3859   // not copied during the pause.
3860   process_discovered_references(per_thread_states);
3861 
3862   G1STWIsAliveClosure is_alive(this);
3863   G1KeepAliveClosure keep_alive(this);
3864 
3865   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3866                               phase_times()->weak_phase_times());
3867 
3868   if (G1StringDedup::is_enabled()) {
3869     double string_dedup_time_ms = os::elapsedTime();
3870 
3871     string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
3872 
3873     double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3874     phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3875   }
3876 
3877   _allocator->release_gc_alloc_regions(evacuation_info);
3878 
3879   if (evacuation_failed()) {
3880     restore_after_evac_failure();
3881 
3882     // Reset the G1EvacuationFailureALot counters and flags
3883     NOT_PRODUCT(reset_evacuation_should_fail();)
3884 
3885     double recalculate_used_start = os::elapsedTime();
3886     set_used(recalculate_used());
3887     phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3888 
3889     if (_archive_allocator != NULL) {
3890       _archive_allocator->clear_used();
3891     }
3892     for (uint i = 0; i < ParallelGCThreads; i++) {
3893       if (_evacuation_failed_info_array[i].has_failed()) {
3894         _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3895       }
3896     }
3897   } else {
3898     // The "used" of the the collection set have already been subtracted
3899     // when they were freed.  Add in the bytes evacuated.
3900     increase_used(policy()->bytes_copied_during_gc());
3901   }
3902 
3903   _preserved_marks_set.assert_empty();
3904 
3905   merge_per_thread_state_info(per_thread_states);
3906 
3907   // Reset and re-enable the hot card cache.
3908   // Note the counts for the cards in the regions in the
3909   // collection set are reset when the collection set is freed.
3910   _hot_card_cache->reset_hot_cache();
3911   _hot_card_cache->set_use_cache(true);
3912 
3913   purge_code_root_memory();
3914 
3915   redirty_logged_cards();
3916 
3917   free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3918 
3919   eagerly_reclaim_humongous_regions();
3920 
3921   record_obj_copy_mem_stats();
3922 
3923   evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3924   evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
3925 
3926 #if COMPILER2_OR_JVMCI
3927   double start = os::elapsedTime();
3928   DerivedPointerTable::update_pointers();
3929   phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3930 #endif
3931   policy()->print_age_table();
3932 }
3933 
3934 void G1CollectedHeap::record_obj_copy_mem_stats() {
3935   policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3936 
3937   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3938                                                create_g1_evac_summary(&_old_evac_stats));
3939 }
3940 
3941 void G1CollectedHeap::free_region(HeapRegion* hr,
3942                                   FreeRegionList* free_list,
3943                                   bool skip_remset,
3944                                   bool skip_hot_card_cache,
3945                                   bool locked) {
3946   assert(!hr->is_free(), "the region should not be free");
3947   assert(!hr->is_empty(), "the region should not be empty");
3948   assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3949   assert(free_list != NULL, "pre-condition");
3950 
3951   if (G1VerifyBitmaps) {
3952     MemRegion mr(hr->bottom(), hr->end());
3953     concurrent_mark()->clear_range_in_prev_bitmap(mr);
3954   }
3955 
3956   // Clear the card counts for this region.
3957   // Note: we only need to do this if the region is not young
3958   // (since we don't refine cards in young regions).
3959   if (!skip_hot_card_cache && !hr->is_young()) {
3960     _hot_card_cache->reset_card_counts(hr);
3961   }
3962   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3963   _policy->remset_tracker()->update_at_free(hr);
3964   free_list->add_ordered(hr);
3965 }
3966 
3967 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3968                                             FreeRegionList* free_list) {
3969   assert(hr->is_humongous(), "this is only for humongous regions");
3970   assert(free_list != NULL, "pre-condition");
3971   hr->clear_humongous();
3972   free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3973 }
3974 
3975 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3976                                            const uint humongous_regions_removed) {
3977   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3978     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3979     _old_set.bulk_remove(old_regions_removed);
3980     _humongous_set.bulk_remove(humongous_regions_removed);
3981   }
3982 
3983 }
3984 
3985 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3986   assert(list != NULL, "list can't be null");
3987   if (!list->is_empty()) {
3988     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3989     _hrm->insert_list_into_free_list(list);
3990   }
3991 }
3992 
3993 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3994   decrease_used(bytes);
3995 }
3996 
3997 class G1FreeCollectionSetTask : public AbstractGangTask {
3998 private:
3999 
4000   // Closure applied to all regions in the collection set to do work that needs to
4001   // be done serially in a single thread.
4002   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4003   private:
4004     G1EvacuationInfo* _evacuation_info;
4005     const size_t* _surviving_young_words;
4006 
4007     // Bytes used in successfully evacuated regions before the evacuation.
4008     size_t _before_used_bytes;
4009     // Bytes used in unsucessfully evacuated regions before the evacuation
4010     size_t _after_used_bytes;
4011 
4012     size_t _bytes_allocated_in_old_since_last_gc;
4013 
4014     size_t _failure_used_words;
4015     size_t _failure_waste_words;
4016 
4017     FreeRegionList _local_free_list;
4018   public:
4019     G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4020       HeapRegionClosure(),
4021       _evacuation_info(evacuation_info),
4022       _surviving_young_words(surviving_young_words),
4023       _before_used_bytes(0),
4024       _after_used_bytes(0),
4025       _bytes_allocated_in_old_since_last_gc(0),
4026       _failure_used_words(0),
4027       _failure_waste_words(0),
4028       _local_free_list("Local Region List for CSet Freeing") {
4029     }
4030 
4031     virtual bool do_heap_region(HeapRegion* r) {
4032       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4033 
4034       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4035       g1h->clear_in_cset(r);
4036 
4037       if (r->is_young()) {
4038         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4039                "Young index %d is wrong for region %u of type %s with %u young regions",
4040                r->young_index_in_cset(),
4041                r->hrm_index(),
4042                r->get_type_str(),
4043                g1h->collection_set()->young_region_length());
4044         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4045         r->record_surv_words_in_group(words_survived);
4046       }
4047 
4048       if (!r->evacuation_failed()) {
4049         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4050         _before_used_bytes += r->used();
4051         g1h->free_region(r,
4052                          &_local_free_list,
4053                          true, /* skip_remset */
4054                          true, /* skip_hot_card_cache */
4055                          true  /* locked */);
4056       } else {
4057         r->uninstall_surv_rate_group();
4058         r->set_young_index_in_cset(-1);
4059         r->set_evacuation_failed(false);
4060         // When moving a young gen region to old gen, we "allocate" that whole region
4061         // there. This is in addition to any already evacuated objects. Notify the
4062         // policy about that.
4063         // Old gen regions do not cause an additional allocation: both the objects
4064         // still in the region and the ones already moved are accounted for elsewhere.
4065         if (r->is_young()) {
4066           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4067         }
4068         // The region is now considered to be old.
4069         r->set_old();
4070         // Do some allocation statistics accounting. Regions that failed evacuation
4071         // are always made old, so there is no need to update anything in the young
4072         // gen statistics, but we need to update old gen statistics.
4073         size_t used_words = r->marked_bytes() / HeapWordSize;
4074 
4075         _failure_used_words += used_words;
4076         _failure_waste_words += HeapRegion::GrainWords - used_words;
4077 
4078         g1h->old_set_add(r);
4079         _after_used_bytes += r->used();
4080       }
4081       return false;
4082     }
4083 
4084     void complete_work() {
4085       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4086 
4087       _evacuation_info->set_regions_freed(_local_free_list.length());
4088       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4089 
4090       g1h->prepend_to_freelist(&_local_free_list);
4091       g1h->decrement_summary_bytes(_before_used_bytes);
4092 
4093       G1Policy* policy = g1h->policy();
4094       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4095 
4096       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4097     }
4098   };
4099 
4100   G1CollectionSet* _collection_set;
4101   G1SerialFreeCollectionSetClosure _cl;
4102   const size_t* _surviving_young_words;
4103 
4104   size_t _rs_lengths;
4105 
4106   volatile jint _serial_work_claim;
4107 
4108   struct WorkItem {
4109     uint region_idx;
4110     bool is_young;
4111     bool evacuation_failed;
4112 
4113     WorkItem(HeapRegion* r) {
4114       region_idx = r->hrm_index();
4115       is_young = r->is_young();
4116       evacuation_failed = r->evacuation_failed();
4117     }
4118   };
4119 
4120   volatile size_t _parallel_work_claim;
4121   size_t _num_work_items;
4122   WorkItem* _work_items;
4123 
4124   void do_serial_work() {
4125     // Need to grab the lock to be allowed to modify the old region list.
4126     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4127     _collection_set->iterate(&_cl);
4128   }
4129 
4130   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4131     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4132 
4133     HeapRegion* r = g1h->region_at(region_idx);
4134     assert(!g1h->is_on_master_free_list(r), "sanity");
4135 
4136     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4137 
4138     if (!is_young) {
4139       g1h->_hot_card_cache->reset_card_counts(r);
4140     }
4141 
4142     if (!evacuation_failed) {
4143       r->rem_set()->clear_locked();
4144     }
4145   }
4146 
4147   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4148   private:
4149     size_t _cur_idx;
4150     WorkItem* _work_items;
4151   public:
4152     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4153 
4154     virtual bool do_heap_region(HeapRegion* r) {
4155       _work_items[_cur_idx++] = WorkItem(r);
4156       return false;
4157     }
4158   };
4159 
4160   void prepare_work() {
4161     G1PrepareFreeCollectionSetClosure cl(_work_items);
4162     _collection_set->iterate(&cl);
4163   }
4164 
4165   void complete_work() {
4166     _cl.complete_work();
4167 
4168     G1Policy* policy = G1CollectedHeap::heap()->policy();
4169     policy->record_max_rs_lengths(_rs_lengths);
4170     policy->cset_regions_freed();
4171   }
4172 public:
4173   G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4174     AbstractGangTask("G1 Free Collection Set"),
4175     _collection_set(collection_set),
4176     _cl(evacuation_info, surviving_young_words),
4177     _surviving_young_words(surviving_young_words),
4178     _rs_lengths(0),
4179     _serial_work_claim(0),
4180     _parallel_work_claim(0),
4181     _num_work_items(collection_set->region_length()),
4182     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4183     prepare_work();
4184   }
4185 
4186   ~G1FreeCollectionSetTask() {
4187     complete_work();
4188     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4189   }
4190 
4191   // Chunk size for work distribution. The chosen value has been determined experimentally
4192   // to be a good tradeoff between overhead and achievable parallelism.
4193   static uint chunk_size() { return 32; }
4194 
4195   virtual void work(uint worker_id) {
4196     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4197 
4198     // Claim serial work.
4199     if (_serial_work_claim == 0) {
4200       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4201       if (value == 0) {
4202         double serial_time = os::elapsedTime();
4203         do_serial_work();
4204         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4205       }
4206     }
4207 
4208     // Start parallel work.
4209     double young_time = 0.0;
4210     bool has_young_time = false;
4211     double non_young_time = 0.0;
4212     bool has_non_young_time = false;
4213 
4214     while (true) {
4215       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4216       size_t cur = end - chunk_size();
4217 
4218       if (cur >= _num_work_items) {
4219         break;
4220       }
4221 
4222       EventGCPhaseParallel event;
4223       double start_time = os::elapsedTime();
4224 
4225       end = MIN2(end, _num_work_items);
4226 
4227       for (; cur < end; cur++) {
4228         bool is_young = _work_items[cur].is_young;
4229 
4230         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4231 
4232         double end_time = os::elapsedTime();
4233         double time_taken = end_time - start_time;
4234         if (is_young) {
4235           young_time += time_taken;
4236           has_young_time = true;
4237           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4238         } else {
4239           non_young_time += time_taken;
4240           has_non_young_time = true;
4241           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4242         }
4243         start_time = end_time;
4244       }
4245     }
4246 
4247     if (has_young_time) {
4248       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4249     }
4250     if (has_non_young_time) {
4251       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4252     }
4253   }
4254 };
4255 
4256 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4257   _eden.clear();
4258 
4259   double free_cset_start_time = os::elapsedTime();
4260 
4261   {
4262     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4263     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4264 
4265     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4266 
4267     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4268                         cl.name(),
4269                         num_workers,
4270                         _collection_set.region_length());
4271     workers()->run_task(&cl, num_workers);
4272   }
4273   phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4274 
4275   collection_set->clear();
4276 }
4277 
4278 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4279  private:
4280   FreeRegionList* _free_region_list;
4281   HeapRegionSet* _proxy_set;
4282   uint _humongous_objects_reclaimed;
4283   uint _humongous_regions_reclaimed;
4284   size_t _freed_bytes;
4285  public:
4286 
4287   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4288     _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4289   }
4290 
4291   virtual bool do_heap_region(HeapRegion* r) {
4292     if (!r->is_starts_humongous()) {
4293       return false;
4294     }
4295 
4296     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4297 
4298     oop obj = (oop)r->bottom();
4299     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4300 
4301     // The following checks whether the humongous object is live are sufficient.
4302     // The main additional check (in addition to having a reference from the roots
4303     // or the young gen) is whether the humongous object has a remembered set entry.
4304     //
4305     // A humongous object cannot be live if there is no remembered set for it
4306     // because:
4307     // - there can be no references from within humongous starts regions referencing
4308     // the object because we never allocate other objects into them.
4309     // (I.e. there are no intra-region references that may be missed by the
4310     // remembered set)
4311     // - as soon there is a remembered set entry to the humongous starts region
4312     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4313     // until the end of a concurrent mark.
4314     //
4315     // It is not required to check whether the object has been found dead by marking
4316     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4317     // all objects allocated during that time are considered live.
4318     // SATB marking is even more conservative than the remembered set.
4319     // So if at this point in the collection there is no remembered set entry,
4320     // nobody has a reference to it.
4321     // At the start of collection we flush all refinement logs, and remembered sets
4322     // are completely up-to-date wrt to references to the humongous object.
4323     //
4324     // Other implementation considerations:
4325     // - never consider object arrays at this time because they would pose
4326     // considerable effort for cleaning up the the remembered sets. This is
4327     // required because stale remembered sets might reference locations that
4328     // are currently allocated into.
4329     uint region_idx = r->hrm_index();
4330     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4331         !r->rem_set()->is_empty()) {
4332       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",
4333                                region_idx,
4334                                (size_t)obj->size() * HeapWordSize,
4335                                p2i(r->bottom()),
4336                                r->rem_set()->occupied(),
4337                                r->rem_set()->strong_code_roots_list_length(),
4338                                next_bitmap->is_marked(r->bottom()),
4339                                g1h->is_humongous_reclaim_candidate(region_idx),
4340                                obj->is_typeArray()
4341                               );
4342       return false;
4343     }
4344 
4345     guarantee(obj->is_typeArray(),
4346               "Only eagerly reclaiming type arrays is supported, but the object "
4347               PTR_FORMAT " is not.", p2i(r->bottom()));
4348 
4349     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",
4350                              region_idx,
4351                              (size_t)obj->size() * HeapWordSize,
4352                              p2i(r->bottom()),
4353                              r->rem_set()->occupied(),
4354                              r->rem_set()->strong_code_roots_list_length(),
4355                              next_bitmap->is_marked(r->bottom()),
4356                              g1h->is_humongous_reclaim_candidate(region_idx),
4357                              obj->is_typeArray()
4358                             );
4359 
4360     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4361     cm->humongous_object_eagerly_reclaimed(r);
4362     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4363            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4364            region_idx,
4365            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4366            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4367     _humongous_objects_reclaimed++;
4368     do {
4369       HeapRegion* next = g1h->next_region_in_humongous(r);
4370       _freed_bytes += r->used();
4371       r->set_containing_set(NULL);
4372       _humongous_regions_reclaimed++;
4373       g1h->free_humongous_region(r, _free_region_list);
4374       r = next;
4375     } while (r != NULL);
4376 
4377     return false;
4378   }
4379 
4380   uint humongous_objects_reclaimed() {
4381     return _humongous_objects_reclaimed;
4382   }
4383 
4384   uint humongous_regions_reclaimed() {
4385     return _humongous_regions_reclaimed;
4386   }
4387 
4388   size_t bytes_freed() const {
4389     return _freed_bytes;
4390   }
4391 };
4392 
4393 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4394   assert_at_safepoint_on_vm_thread();
4395 
4396   if (!G1EagerReclaimHumongousObjects ||
4397       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4398     phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4399     return;
4400   }
4401 
4402   double start_time = os::elapsedTime();
4403 
4404   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4405 
4406   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4407   heap_region_iterate(&cl);
4408 
4409   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4410 
4411   G1HRPrinter* hrp = hr_printer();
4412   if (hrp->is_active()) {
4413     FreeRegionListIterator iter(&local_cleanup_list);
4414     while (iter.more_available()) {
4415       HeapRegion* hr = iter.get_next();
4416       hrp->cleanup(hr);
4417     }
4418   }
4419 
4420   prepend_to_freelist(&local_cleanup_list);
4421   decrement_summary_bytes(cl.bytes_freed());
4422 
4423   phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4424                                                        cl.humongous_objects_reclaimed());
4425 }
4426 
4427 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4428 public:
4429   virtual bool do_heap_region(HeapRegion* r) {
4430     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4431     G1CollectedHeap::heap()->clear_in_cset(r);
4432     r->set_young_index_in_cset(-1);
4433     return false;
4434   }
4435 };
4436 
4437 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4438   G1AbandonCollectionSetClosure cl;
4439   collection_set->iterate(&cl);
4440 
4441   collection_set->clear();
4442   collection_set->stop_incremental_building();
4443 }
4444 
4445 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4446   return _allocator->is_retained_old_region(hr);
4447 }
4448 
4449 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4450   _eden.add(hr);
4451   _policy->set_region_eden(hr);
4452 }
4453 
4454 #ifdef ASSERT
4455 
4456 class NoYoungRegionsClosure: public HeapRegionClosure {
4457 private:
4458   bool _success;
4459 public:
4460   NoYoungRegionsClosure() : _success(true) { }
4461   bool do_heap_region(HeapRegion* r) {
4462     if (r->is_young()) {
4463       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4464                             p2i(r->bottom()), p2i(r->end()));
4465       _success = false;
4466     }
4467     return false;
4468   }
4469   bool success() { return _success; }
4470 };
4471 
4472 bool G1CollectedHeap::check_young_list_empty() {
4473   bool ret = (young_regions_count() == 0);
4474 
4475   NoYoungRegionsClosure closure;
4476   heap_region_iterate(&closure);
4477   ret = ret && closure.success();
4478 
4479   return ret;
4480 }
4481 
4482 #endif // ASSERT
4483 
4484 class TearDownRegionSetsClosure : public HeapRegionClosure {
4485   HeapRegionSet *_old_set;
4486 
4487 public:
4488   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4489 
4490   bool do_heap_region(HeapRegion* r) {
4491     if (r->is_old()) {
4492       _old_set->remove(r);
4493     } else if(r->is_young()) {
4494       r->uninstall_surv_rate_group();
4495     } else {
4496       // We ignore free regions, we'll empty the free list afterwards.
4497       // We ignore humongous and archive regions, we're not tearing down these
4498       // sets.
4499       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4500              "it cannot be another type");
4501     }
4502     return false;
4503   }
4504 
4505   ~TearDownRegionSetsClosure() {
4506     assert(_old_set->is_empty(), "post-condition");
4507   }
4508 };
4509 
4510 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4511   assert_at_safepoint_on_vm_thread();
4512 
4513   if (!free_list_only) {
4514     TearDownRegionSetsClosure cl(&_old_set);
4515     heap_region_iterate(&cl);
4516 
4517     // Note that emptying the _young_list is postponed and instead done as
4518     // the first step when rebuilding the regions sets again. The reason for
4519     // this is that during a full GC string deduplication needs to know if
4520     // a collected region was young or old when the full GC was initiated.
4521   }
4522   _hrm->remove_all_free_regions();
4523 }
4524 
4525 void G1CollectedHeap::increase_used(size_t bytes) {
4526   _summary_bytes_used += bytes;
4527 }
4528 
4529 void G1CollectedHeap::decrease_used(size_t bytes) {
4530   assert(_summary_bytes_used >= bytes,
4531          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4532          _summary_bytes_used, bytes);
4533   _summary_bytes_used -= bytes;
4534 }
4535 
4536 void G1CollectedHeap::set_used(size_t bytes) {
4537   _summary_bytes_used = bytes;
4538 }
4539 
4540 class RebuildRegionSetsClosure : public HeapRegionClosure {
4541 private:
4542   bool _free_list_only;
4543 
4544   HeapRegionSet* _old_set;
4545   HeapRegionManager* _hrm;
4546 
4547   size_t _total_used;
4548 
4549 public:
4550   RebuildRegionSetsClosure(bool free_list_only,
4551                            HeapRegionSet* old_set,
4552                            HeapRegionManager* hrm) :
4553     _free_list_only(free_list_only),
4554     _old_set(old_set), _hrm(hrm), _total_used(0) {
4555     assert(_hrm->num_free_regions() == 0, "pre-condition");
4556     if (!free_list_only) {
4557       assert(_old_set->is_empty(), "pre-condition");
4558     }
4559   }
4560 
4561   bool do_heap_region(HeapRegion* r) {
4562     if (r->is_empty()) {
4563       assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4564       // Add free regions to the free list
4565       r->set_free();
4566       _hrm->insert_into_free_list(r);
4567     } else if (!_free_list_only) {
4568       assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4569 
4570       if (r->is_archive() || r->is_humongous()) {
4571         // We ignore archive and humongous regions. We left these sets unchanged.
4572       } else {
4573         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4574         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4575         r->move_to_old();
4576         _old_set->add(r);
4577       }
4578       _total_used += r->used();
4579     }
4580 
4581     return false;
4582   }
4583 
4584   size_t total_used() {
4585     return _total_used;
4586   }
4587 };
4588 
4589 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4590   assert_at_safepoint_on_vm_thread();
4591 
4592   if (!free_list_only) {
4593     _eden.clear();
4594     _survivor.clear();
4595   }
4596 
4597   RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4598   heap_region_iterate(&cl);
4599 
4600   if (!free_list_only) {
4601     set_used(cl.total_used());
4602     if (_archive_allocator != NULL) {
4603       _archive_allocator->clear_used();
4604     }
4605   }
4606   assert(used() == recalculate_used(),
4607          "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4608          used(), recalculate_used());
4609 }
4610 
4611 // Methods for the mutator alloc region
4612 
4613 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4614                                                       bool force) {
4615   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4616   bool should_allocate = policy()->should_allocate_mutator_region();
4617   if (force || should_allocate) {
4618     HeapRegion* new_alloc_region = new_region(word_size,
4619                                               HeapRegionType::Eden,
4620                                               false /* do_expand */);
4621     if (new_alloc_region != NULL) {
4622       set_region_short_lived_locked(new_alloc_region);
4623       _hr_printer.alloc(new_alloc_region, !should_allocate);
4624       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4625       _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4626       return new_alloc_region;
4627     }
4628   }
4629   return NULL;
4630 }
4631 
4632 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4633                                                   size_t allocated_bytes) {
4634   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4635   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4636 
4637   collection_set()->add_eden_region(alloc_region);
4638   increase_used(allocated_bytes);
4639   _hr_printer.retire(alloc_region);
4640   // We update the eden sizes here, when the region is retired,
4641   // instead of when it's allocated, since this is the point that its
4642   // used space has been recorded in _summary_bytes_used.
4643   g1mm()->update_eden_size();
4644 }
4645 
4646 // Methods for the GC alloc regions
4647 
4648 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4649   if (dest.is_old()) {
4650     return true;
4651   } else {
4652     return survivor_regions_count() < policy()->max_survivor_regions();
4653   }
4654 }
4655 
4656 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4657   assert(FreeList_lock->owned_by_self(), "pre-condition");
4658 
4659   if (!has_more_regions(dest)) {
4660     return NULL;
4661   }
4662 
4663   HeapRegionType type;
4664   if (dest.is_young()) {
4665     type = HeapRegionType::Survivor;
4666   } else {
4667     type = HeapRegionType::Old;
4668   }
4669 
4670   HeapRegion* new_alloc_region = new_region(word_size,
4671                                             type,
4672                                             true /* do_expand */);
4673 
4674   if (new_alloc_region != NULL) {
4675     if (type.is_survivor()) {
4676       new_alloc_region->set_survivor();
4677       _survivor.add(new_alloc_region);
4678       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4679     } else {
4680       new_alloc_region->set_old();
4681       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4682     }
4683     _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4684     _hr_printer.alloc(new_alloc_region);
4685     return new_alloc_region;
4686   }
4687   return NULL;
4688 }
4689 
4690 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4691                                              size_t allocated_bytes,
4692                                              InCSetState dest) {
4693   policy()->record_bytes_copied_during_gc(allocated_bytes);
4694   if (dest.is_old()) {
4695     old_set_add(alloc_region);
4696   }
4697 
4698   bool const during_im = collector_state()->in_initial_mark_gc();
4699   if (during_im && allocated_bytes > 0) {
4700     _cm->root_regions()->add(alloc_region);
4701   }
4702   _hr_printer.retire(alloc_region);
4703 }
4704 
4705 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4706   bool expanded = false;
4707   uint index = _hrm->find_highest_free(&expanded);
4708 
4709   if (index != G1_NO_HRM_INDEX) {
4710     if (expanded) {
4711       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4712                                 HeapRegion::GrainWords * HeapWordSize);
4713     }
4714     _hrm->allocate_free_regions_starting_at(index, 1);
4715     return region_at(index);
4716   }
4717   return NULL;
4718 }
4719 
4720 // Optimized nmethod scanning
4721 
4722 class RegisterNMethodOopClosure: public OopClosure {
4723   G1CollectedHeap* _g1h;
4724   nmethod* _nm;
4725 
4726   template <class T> void do_oop_work(T* p) {
4727     T heap_oop = RawAccess<>::oop_load(p);
4728     if (!CompressedOops::is_null(heap_oop)) {
4729       oop obj = CompressedOops::decode_not_null(heap_oop);
4730       HeapRegion* hr = _g1h->heap_region_containing(obj);
4731       assert(!hr->is_continues_humongous(),
4732              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4733              " starting at " HR_FORMAT,
4734              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4735 
4736       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4737       hr->add_strong_code_root_locked(_nm);
4738     }
4739   }
4740 
4741 public:
4742   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4743     _g1h(g1h), _nm(nm) {}
4744 
4745   void do_oop(oop* p)       { do_oop_work(p); }
4746   void do_oop(narrowOop* p) { do_oop_work(p); }
4747 };
4748 
4749 class UnregisterNMethodOopClosure: public OopClosure {
4750   G1CollectedHeap* _g1h;
4751   nmethod* _nm;
4752 
4753   template <class T> void do_oop_work(T* p) {
4754     T heap_oop = RawAccess<>::oop_load(p);
4755     if (!CompressedOops::is_null(heap_oop)) {
4756       oop obj = CompressedOops::decode_not_null(heap_oop);
4757       HeapRegion* hr = _g1h->heap_region_containing(obj);
4758       assert(!hr->is_continues_humongous(),
4759              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4760              " starting at " HR_FORMAT,
4761              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4762 
4763       hr->remove_strong_code_root(_nm);
4764     }
4765   }
4766 
4767 public:
4768   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4769     _g1h(g1h), _nm(nm) {}
4770 
4771   void do_oop(oop* p)       { do_oop_work(p); }
4772   void do_oop(narrowOop* p) { do_oop_work(p); }
4773 };
4774 
4775 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4776   guarantee(nm != NULL, "sanity");
4777   RegisterNMethodOopClosure reg_cl(this, nm);
4778   nm->oops_do(&reg_cl);
4779 }
4780 
4781 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4782   guarantee(nm != NULL, "sanity");
4783   UnregisterNMethodOopClosure reg_cl(this, nm);
4784   nm->oops_do(&reg_cl, true);
4785 }
4786 
4787 void G1CollectedHeap::purge_code_root_memory() {
4788   double purge_start = os::elapsedTime();
4789   G1CodeRootSet::purge();
4790   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4791   phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4792 }
4793 
4794 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4795   G1CollectedHeap* _g1h;
4796 
4797 public:
4798   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4799     _g1h(g1h) {}
4800 
4801   void do_code_blob(CodeBlob* cb) {
4802     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4803     if (nm == NULL) {
4804       return;
4805     }
4806 
4807     _g1h->register_nmethod(nm);
4808   }
4809 };
4810 
4811 void G1CollectedHeap::rebuild_strong_code_roots() {
4812   RebuildStrongCodeRootClosure blob_cl(this);
4813   CodeCache::blobs_do(&blob_cl);
4814 }
4815 
4816 void G1CollectedHeap::initialize_serviceability() {
4817   _g1mm->initialize_serviceability();
4818 }
4819 
4820 MemoryUsage G1CollectedHeap::memory_usage() {
4821   return _g1mm->memory_usage();
4822 }
4823 
4824 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4825   return _g1mm->memory_managers();
4826 }
4827 
4828 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4829   return _g1mm->memory_pools();
4830 }