1 /*
   2  * Copyright (c) 2001, 2018, 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/metadataOnStackMark.hpp"
  27 #include "classfile/stringTable.hpp"
  28 #include "classfile/symbolTable.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "gc/g1/g1Allocator.inline.hpp"
  32 #include "gc/g1/g1CollectedHeap.inline.hpp"
  33 #include "gc/g1/g1CollectionSet.hpp"
  34 #include "gc/g1/g1CollectorPolicy.hpp"
  35 #include "gc/g1/g1CollectorState.hpp"
  36 #include "gc/g1/g1ConcurrentRefine.hpp"
  37 #include "gc/g1/g1ConcurrentRefineThread.hpp"
  38 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
  39 #include "gc/g1/g1EvacStats.inline.hpp"
  40 #include "gc/g1/g1FullCollector.hpp"
  41 #include "gc/g1/g1GCPhaseTimes.hpp"
  42 #include "gc/g1/g1HeapSizingPolicy.hpp"
  43 #include "gc/g1/g1HeapTransition.hpp"
  44 #include "gc/g1/g1HeapVerifier.hpp"
  45 #include "gc/g1/g1HotCardCache.hpp"
  46 #include "gc/g1/g1MemoryPool.hpp"
  47 #include "gc/g1/g1OopClosures.inline.hpp"
  48 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  49 #include "gc/g1/g1Policy.hpp"
  50 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  51 #include "gc/g1/g1RemSet.hpp"
  52 #include "gc/g1/g1RootClosures.hpp"
  53 #include "gc/g1/g1RootProcessor.hpp"
  54 #include "gc/g1/g1StringDedup.hpp"
  55 #include "gc/g1/g1YCTypes.hpp"
  56 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  57 #include "gc/g1/heapRegion.inline.hpp"
  58 #include "gc/g1/heapRegionRemSet.hpp"
  59 #include "gc/g1/heapRegionSet.inline.hpp"
  60 #include "gc/g1/vm_operations_g1.hpp"
  61 #include "gc/shared/adaptiveSizePolicy.hpp"
  62 #include "gc/shared/gcHeapSummary.hpp"
  63 #include "gc/shared/gcId.hpp"
  64 #include "gc/shared/gcLocker.hpp"
  65 #include "gc/shared/gcTimer.hpp"
  66 #include "gc/shared/gcTrace.hpp"
  67 #include "gc/shared/gcTraceTime.inline.hpp"
  68 #include "gc/shared/generationSpec.hpp"
  69 #include "gc/shared/isGCActiveMark.hpp"
  70 #include "gc/shared/preservedMarks.inline.hpp"
  71 #include "gc/shared/suspendibleThreadSet.hpp"
  72 #include "gc/shared/referenceProcessor.inline.hpp"
  73 #include "gc/shared/taskqueue.inline.hpp"
  74 #include "gc/shared/weakProcessor.hpp"
  75 #include "logging/log.hpp"
  76 #include "memory/allocation.hpp"
  77 #include "memory/iterator.hpp"
  78 #include "memory/resourceArea.hpp"
  79 #include "oops/access.inline.hpp"
  80 #include "oops/compressedOops.inline.hpp"
  81 #include "oops/oop.inline.hpp"
  82 #include "prims/resolvedMethodTable.hpp"
  83 #include "runtime/atomic.hpp"
  84 #include "runtime/handles.inline.hpp"
  85 #include "runtime/init.hpp"
  86 #include "runtime/orderAccess.inline.hpp"
  87 #include "runtime/threadSMR.hpp"
  88 #include "runtime/vmThread.hpp"
  89 #include "utilities/align.hpp"
  90 #include "utilities/globalDefinitions.hpp"
  91 #include "utilities/stack.inline.hpp"
  92 
  93 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  94 
  95 // INVARIANTS/NOTES
  96 //
  97 // All allocation activity covered by the G1CollectedHeap interface is
  98 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  99 // and allocate_new_tlab, which are the "entry" points to the
 100 // allocation code from the rest of the JVM.  (Note that this does not
 101 // apply to TLAB allocation, which is not part of this interface: it
 102 // is done by clients of this interface.)
 103 
 104 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 105  private:
 106   size_t _num_dirtied;
 107   G1CollectedHeap* _g1h;
 108   G1CardTable* _g1_ct;
 109 
 110   HeapRegion* region_for_card(jbyte* card_ptr) const {
 111     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
 112   }
 113 
 114   bool will_become_free(HeapRegion* hr) const {
 115     // A region will be freed by free_collection_set if the region is in the
 116     // collection set and has not had an evacuation failure.
 117     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 118   }
 119 
 120  public:
 121   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 122     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
 123 
 124   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 125     HeapRegion* hr = region_for_card(card_ptr);
 126 
 127     // Should only dirty cards in regions that won't be freed.
 128     if (!will_become_free(hr)) {
 129       *card_ptr = G1CardTable::dirty_card_val();
 130       _num_dirtied++;
 131     }
 132 
 133     return true;
 134   }
 135 
 136   size_t num_dirtied()   const { return _num_dirtied; }
 137 };
 138 
 139 
 140 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 141   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 142 }
 143 
 144 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 145   // The from card cache is not the memory that is actually committed. So we cannot
 146   // take advantage of the zero_filled parameter.
 147   reset_from_card_cache(start_idx, num_regions);
 148 }
 149 
 150 
 151 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 152                                              MemRegion mr) {
 153   return new HeapRegion(hrs_index, bot(), mr);
 154 }
 155 
 156 // Private methods.
 157 
 158 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 159   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 160          "the only time we use this to allocate a humongous region is "
 161          "when we are allocating a single humongous region");
 162 
 163   HeapRegion* res = _hrm.allocate_free_region(is_old);
 164 
 165   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 166     // Currently, only attempts to allocate GC alloc regions set
 167     // do_expand to true. So, we should only reach here during a
 168     // safepoint. If this assumption changes we might have to
 169     // reconsider the use of _expand_heap_after_alloc_failure.
 170     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 171 
 172     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 173                               word_size * HeapWordSize);
 174 
 175     if (expand(word_size * HeapWordSize)) {
 176       // Given that expand() succeeded in expanding the heap, and we
 177       // always expand the heap by an amount aligned to the heap
 178       // region size, the free list should in theory not be empty.
 179       // In either case allocate_free_region() will check for NULL.
 180       res = _hrm.allocate_free_region(is_old);
 181     } else {
 182       _expand_heap_after_alloc_failure = false;
 183     }
 184   }
 185   return res;
 186 }
 187 
 188 HeapWord*
 189 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 190                                                            uint num_regions,
 191                                                            size_t word_size) {
 192   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 193   assert(is_humongous(word_size), "word_size should be humongous");
 194   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 195 
 196   // Index of last region in the series.
 197   uint last = first + num_regions - 1;
 198 
 199   // We need to initialize the region(s) we just discovered. This is
 200   // a bit tricky given that it can happen concurrently with
 201   // refinement threads refining cards on these regions and
 202   // potentially wanting to refine the BOT as they are scanning
 203   // those cards (this can happen shortly after a cleanup; see CR
 204   // 6991377). So we have to set up the region(s) carefully and in
 205   // a specific order.
 206 
 207   // The word size sum of all the regions we will allocate.
 208   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 209   assert(word_size <= word_size_sum, "sanity");
 210 
 211   // This will be the "starts humongous" region.
 212   HeapRegion* first_hr = region_at(first);
 213   // The header of the new object will be placed at the bottom of
 214   // the first region.
 215   HeapWord* new_obj = first_hr->bottom();
 216   // This will be the new top of the new object.
 217   HeapWord* obj_top = new_obj + word_size;
 218 
 219   // First, we need to zero the header of the space that we will be
 220   // allocating. When we update top further down, some refinement
 221   // threads might try to scan the region. By zeroing the header we
 222   // ensure that any thread that will try to scan the region will
 223   // come across the zero klass word and bail out.
 224   //
 225   // NOTE: It would not have been correct to have used
 226   // CollectedHeap::fill_with_object() and make the space look like
 227   // an int array. The thread that is doing the allocation will
 228   // later update the object header to a potentially different array
 229   // type and, for a very short period of time, the klass and length
 230   // fields will be inconsistent. This could cause a refinement
 231   // thread to calculate the object size incorrectly.
 232   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 233 
 234   // Next, pad out the unused tail of the last region with filler
 235   // objects, for improved usage accounting.
 236   // How many words we use for filler objects.
 237   size_t word_fill_size = word_size_sum - word_size;
 238 
 239   // How many words memory we "waste" which cannot hold a filler object.
 240   size_t words_not_fillable = 0;
 241 
 242   if (word_fill_size >= min_fill_size()) {
 243     fill_with_objects(obj_top, word_fill_size);
 244   } else if (word_fill_size > 0) {
 245     // We have space to fill, but we cannot fit an object there.
 246     words_not_fillable = word_fill_size;
 247     word_fill_size = 0;
 248   }
 249 
 250   // We will set up the first region as "starts humongous". This
 251   // will also update the BOT covering all the regions to reflect
 252   // that there is a single object that starts at the bottom of the
 253   // first region.
 254   first_hr->set_starts_humongous(obj_top, word_fill_size);
 255   _g1_policy->remset_tracker()->update_at_allocate(first_hr);
 256   // Then, if there are any, we will set up the "continues
 257   // humongous" regions.
 258   HeapRegion* hr = NULL;
 259   for (uint i = first + 1; i <= last; ++i) {
 260     hr = region_at(i);
 261     hr->set_continues_humongous(first_hr);
 262     _g1_policy->remset_tracker()->update_at_allocate(hr);
 263   }
 264 
 265   // Up to this point no concurrent thread would have been able to
 266   // do any scanning on any region in this series. All the top
 267   // fields still point to bottom, so the intersection between
 268   // [bottom,top] and [card_start,card_end] will be empty. Before we
 269   // update the top fields, we'll do a storestore to make sure that
 270   // no thread sees the update to top before the zeroing of the
 271   // object header and the BOT initialization.
 272   OrderAccess::storestore();
 273 
 274   // Now, we will update the top fields of the "continues humongous"
 275   // regions except the last one.
 276   for (uint i = first; i < last; ++i) {
 277     hr = region_at(i);
 278     hr->set_top(hr->end());
 279   }
 280 
 281   hr = region_at(last);
 282   // If we cannot fit a filler object, we must set top to the end
 283   // of the humongous object, otherwise we cannot iterate the heap
 284   // and the BOT will not be complete.
 285   hr->set_top(hr->end() - words_not_fillable);
 286 
 287   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 288          "obj_top should be in last region");
 289 
 290   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 291 
 292   assert(words_not_fillable == 0 ||
 293          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 294          "Miscalculation in humongous allocation");
 295 
 296   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 297 
 298   for (uint i = first; i <= last; ++i) {
 299     hr = region_at(i);
 300     _humongous_set.add(hr);
 301     _hr_printer.alloc(hr);
 302   }
 303 
 304   return new_obj;
 305 }
 306 
 307 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 308   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 309   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 310 }
 311 
 312 // If could fit into free regions w/o expansion, try.
 313 // Otherwise, if can expand, do so.
 314 // Otherwise, if using ex regions might help, try with ex given back.
 315 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 316   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 317 
 318   _verifier->verify_region_sets_optional();
 319 
 320   uint first = G1_NO_HRM_INDEX;
 321   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 322 
 323   if (obj_regions == 1) {
 324     // Only one region to allocate, try to use a fast path by directly allocating
 325     // from the free lists. Do not try to expand here, we will potentially do that
 326     // later.
 327     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 328     if (hr != NULL) {
 329       first = hr->hrm_index();
 330     }
 331   } else {
 332     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 333     // are lucky enough to find some.
 334     first = _hrm.find_contiguous_only_empty(obj_regions);
 335     if (first != G1_NO_HRM_INDEX) {
 336       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 337     }
 338   }
 339 
 340   if (first == G1_NO_HRM_INDEX) {
 341     // Policy: We could not find enough regions for the humongous object in the
 342     // free list. Look through the heap to find a mix of free and uncommitted regions.
 343     // If so, try expansion.
 344     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 345     if (first != G1_NO_HRM_INDEX) {
 346       // We found something. Make sure these regions are committed, i.e. expand
 347       // the heap. Alternatively we could do a defragmentation GC.
 348       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 349                                     word_size * HeapWordSize);
 350 
 351       _hrm.expand_at(first, obj_regions, workers());
 352       g1_policy()->record_new_heap_size(num_regions());
 353 
 354 #ifdef ASSERT
 355       for (uint i = first; i < first + obj_regions; ++i) {
 356         HeapRegion* hr = region_at(i);
 357         assert(hr->is_free(), "sanity");
 358         assert(hr->is_empty(), "sanity");
 359         assert(is_on_master_free_list(hr), "sanity");
 360       }
 361 #endif
 362       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 363     } else {
 364       // Policy: Potentially trigger a defragmentation GC.
 365     }
 366   }
 367 
 368   HeapWord* result = NULL;
 369   if (first != G1_NO_HRM_INDEX) {
 370     result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
 371     assert(result != NULL, "it should always return a valid result");
 372 
 373     // A successful humongous object allocation changes the used space
 374     // information of the old generation so we need to recalculate the
 375     // sizes and update the jstat counters here.
 376     g1mm()->update_sizes();
 377   }
 378 
 379   _verifier->verify_region_sets_optional();
 380 
 381   return result;
 382 }
 383 
 384 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 385   assert_heap_not_locked_and_not_at_safepoint();
 386   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 387 
 388   return attempt_allocation(word_size);
 389 }
 390 
 391 HeapWord*
 392 G1CollectedHeap::mem_allocate(size_t word_size,
 393                               bool*  gc_overhead_limit_was_exceeded) {
 394   assert_heap_not_locked_and_not_at_safepoint();
 395 
 396   if (is_humongous(word_size)) {
 397     return attempt_allocation_humongous(word_size);
 398   }
 399   return attempt_allocation(word_size);
 400 }
 401 
 402 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 403   ResourceMark rm; // For retrieving the thread names in log messages.
 404 
 405   // Make sure you read the note in attempt_allocation_humongous().
 406 
 407   assert_heap_not_locked_and_not_at_safepoint();
 408   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 409          "be called for humongous allocation requests");
 410 
 411   // We should only get here after the first-level allocation attempt
 412   // (attempt_allocation()) failed to allocate.
 413 
 414   // We will loop until a) we manage to successfully perform the
 415   // allocation or b) we successfully schedule a collection which
 416   // fails to perform the allocation. b) is the only case when we'll
 417   // return NULL.
 418   HeapWord* result = NULL;
 419   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 420     bool should_try_gc;
 421     uint gc_count_before;
 422 
 423     {
 424       MutexLockerEx x(Heap_lock);
 425       result = _allocator->attempt_allocation_locked(word_size);
 426       if (result != NULL) {
 427         return result;
 428       }
 429 
 430       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 431       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 432       // waiting because the GCLocker is active to not wait too long.
 433       if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
 434         // No need for an ergo message here, can_expand_young_list() does this when
 435         // it returns true.
 436         result = _allocator->attempt_allocation_force(word_size);
 437         if (result != NULL) {
 438           return result;
 439         }
 440       }
 441       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 442       // the GCLocker initiated GC has been performed and then retry. This includes
 443       // the case when the GC Locker is not active but has not been performed.
 444       should_try_gc = !GCLocker::needs_gc();
 445       // Read the GC count while still holding the Heap_lock.
 446       gc_count_before = total_collections();
 447     }
 448 
 449     if (should_try_gc) {
 450       bool succeeded;
 451       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 452                                    GCCause::_g1_inc_collection_pause);
 453       if (result != NULL) {
 454         assert(succeeded, "only way to get back a non-NULL result");
 455         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 456                              Thread::current()->name(), p2i(result));
 457         return result;
 458       }
 459 
 460       if (succeeded) {
 461         // We successfully scheduled a collection which failed to allocate. No
 462         // point in trying to allocate further. We'll just return NULL.
 463         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 464                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 465         return NULL;
 466       }
 467       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 468                            Thread::current()->name(), word_size);
 469     } else {
 470       // Failed to schedule a collection.
 471       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 472         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 473                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 474         return NULL;
 475       }
 476       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 477       // The GCLocker is either active or the GCLocker initiated
 478       // GC has not yet been performed. Stall until it is and
 479       // then retry the allocation.
 480       GCLocker::stall_until_clear();
 481       gclocker_retry_count += 1;
 482     }
 483 
 484     // We can reach here if we were unsuccessful in scheduling a
 485     // collection (because another thread beat us to it) or if we were
 486     // stalled due to the GC locker. In either can we should retry the
 487     // allocation attempt in case another thread successfully
 488     // performed a collection and reclaimed enough space. We do the
 489     // first attempt (without holding the Heap_lock) here and the
 490     // follow-on attempt will be at the start of the next loop
 491     // iteration (after taking the Heap_lock).
 492 
 493     result = _allocator->attempt_allocation(word_size);
 494     if (result != NULL) {
 495       return result;
 496     }
 497 
 498     // Give a warning if we seem to be looping forever.
 499     if ((QueuedAllocationWarningCount > 0) &&
 500         (try_count % QueuedAllocationWarningCount == 0)) {
 501       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 502                              Thread::current()->name(), try_count, word_size);
 503     }
 504   }
 505 
 506   ShouldNotReachHere();
 507   return NULL;
 508 }
 509 
 510 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 511   assert_at_safepoint_on_vm_thread();
 512   if (_archive_allocator == NULL) {
 513     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 514   }
 515 }
 516 
 517 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 518   // Allocations in archive regions cannot be of a size that would be considered
 519   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 520   // may be different at archive-restore time.
 521   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 522 }
 523 
 524 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 525   assert_at_safepoint_on_vm_thread();
 526   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 527   if (is_archive_alloc_too_large(word_size)) {
 528     return NULL;
 529   }
 530   return _archive_allocator->archive_mem_allocate(word_size);
 531 }
 532 
 533 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 534                                               size_t end_alignment_in_bytes) {
 535   assert_at_safepoint_on_vm_thread();
 536   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 537 
 538   // Call complete_archive to do the real work, filling in the MemRegion
 539   // array with the archive regions.
 540   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 541   delete _archive_allocator;
 542   _archive_allocator = NULL;
 543 }
 544 
 545 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 546   assert(ranges != NULL, "MemRegion array NULL");
 547   assert(count != 0, "No MemRegions provided");
 548   MemRegion reserved = _hrm.reserved();
 549   for (size_t i = 0; i < count; i++) {
 550     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 551       return false;
 552     }
 553   }
 554   return true;
 555 }
 556 
 557 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 558                                             size_t count,
 559                                             bool open) {
 560   assert(!is_init_completed(), "Expect to be called at JVM init time");
 561   assert(ranges != NULL, "MemRegion array NULL");
 562   assert(count != 0, "No MemRegions provided");
 563   MutexLockerEx x(Heap_lock);
 564 
 565   MemRegion reserved = _hrm.reserved();
 566   HeapWord* prev_last_addr = NULL;
 567   HeapRegion* prev_last_region = NULL;
 568 
 569   // Temporarily disable pretouching of heap pages. This interface is used
 570   // when mmap'ing archived heap data in, so pre-touching is wasted.
 571   FlagSetting fs(AlwaysPreTouch, false);
 572 
 573   // Enable archive object checking used by G1MarkSweep. We have to let it know
 574   // about each archive range, so that objects in those ranges aren't marked.
 575   G1ArchiveAllocator::enable_archive_object_check();
 576 
 577   // For each specified MemRegion range, allocate the corresponding G1
 578   // regions and mark them as archive regions. We expect the ranges
 579   // in ascending starting address order, without overlap.
 580   for (size_t i = 0; i < count; i++) {
 581     MemRegion curr_range = ranges[i];
 582     HeapWord* start_address = curr_range.start();
 583     size_t word_size = curr_range.word_size();
 584     HeapWord* last_address = curr_range.last();
 585     size_t commits = 0;
 586 
 587     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 588               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 589               p2i(start_address), p2i(last_address));
 590     guarantee(start_address > prev_last_addr,
 591               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 592               p2i(start_address), p2i(prev_last_addr));
 593     prev_last_addr = last_address;
 594 
 595     // Check for ranges that start in the same G1 region in which the previous
 596     // range ended, and adjust the start address so we don't try to allocate
 597     // the same region again. If the current range is entirely within that
 598     // region, skip it, just adjusting the recorded top.
 599     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 600     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 601       start_address = start_region->end();
 602       if (start_address > last_address) {
 603         increase_used(word_size * HeapWordSize);
 604         start_region->set_top(last_address + 1);
 605         continue;
 606       }
 607       start_region->set_top(start_address);
 608       curr_range = MemRegion(start_address, last_address + 1);
 609       start_region = _hrm.addr_to_region(start_address);
 610     }
 611 
 612     // Perform the actual region allocation, exiting if it fails.
 613     // Then note how much new space we have allocated.
 614     if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
 615       return false;
 616     }
 617     increase_used(word_size * HeapWordSize);
 618     if (commits != 0) {
 619       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 620                                 HeapRegion::GrainWords * HeapWordSize * commits);
 621 
 622     }
 623 
 624     // Mark each G1 region touched by the range as archive, add it to
 625     // the old set, and set top.
 626     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 627     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 628     prev_last_region = last_region;
 629 
 630     while (curr_region != NULL) {
 631       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 632              "Region already in use (index %u)", curr_region->hrm_index());
 633       if (open) {
 634         curr_region->set_open_archive();
 635       } else {
 636         curr_region->set_closed_archive();
 637       }
 638       _hr_printer.alloc(curr_region);
 639       _old_set.add(curr_region);
 640       HeapWord* top;
 641       HeapRegion* next_region;
 642       if (curr_region != last_region) {
 643         top = curr_region->end();
 644         next_region = _hrm.next_region_in_heap(curr_region);
 645       } else {
 646         top = last_address + 1;
 647         next_region = NULL;
 648       }
 649       curr_region->set_top(top);
 650       curr_region->set_first_dead(top);
 651       curr_region->set_end_of_live(top);
 652       curr_region = next_region;
 653     }
 654 
 655     // Notify mark-sweep of the archive
 656     G1ArchiveAllocator::set_range_archive(curr_range, open);
 657   }
 658   return true;
 659 }
 660 
 661 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 662   assert(!is_init_completed(), "Expect to be called at JVM init time");
 663   assert(ranges != NULL, "MemRegion array NULL");
 664   assert(count != 0, "No MemRegions provided");
 665   MemRegion reserved = _hrm.reserved();
 666   HeapWord *prev_last_addr = NULL;
 667   HeapRegion* prev_last_region = NULL;
 668 
 669   // For each MemRegion, create filler objects, if needed, in the G1 regions
 670   // that contain the address range. The address range actually within the
 671   // MemRegion will not be modified. That is assumed to have been initialized
 672   // elsewhere, probably via an mmap of archived heap data.
 673   MutexLockerEx x(Heap_lock);
 674   for (size_t i = 0; i < count; i++) {
 675     HeapWord* start_address = ranges[i].start();
 676     HeapWord* last_address = ranges[i].last();
 677 
 678     assert(reserved.contains(start_address) && reserved.contains(last_address),
 679            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 680            p2i(start_address), p2i(last_address));
 681     assert(start_address > prev_last_addr,
 682            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 683            p2i(start_address), p2i(prev_last_addr));
 684 
 685     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 686     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 687     HeapWord* bottom_address = start_region->bottom();
 688 
 689     // Check for a range beginning in the same region in which the
 690     // previous one ended.
 691     if (start_region == prev_last_region) {
 692       bottom_address = prev_last_addr + 1;
 693     }
 694 
 695     // Verify that the regions were all marked as archive regions by
 696     // alloc_archive_regions.
 697     HeapRegion* curr_region = start_region;
 698     while (curr_region != NULL) {
 699       guarantee(curr_region->is_archive(),
 700                 "Expected archive region at index %u", curr_region->hrm_index());
 701       if (curr_region != last_region) {
 702         curr_region = _hrm.next_region_in_heap(curr_region);
 703       } else {
 704         curr_region = NULL;
 705       }
 706     }
 707 
 708     prev_last_addr = last_address;
 709     prev_last_region = last_region;
 710 
 711     // Fill the memory below the allocated range with dummy object(s),
 712     // if the region bottom does not match the range start, or if the previous
 713     // range ended within the same G1 region, and there is a gap.
 714     if (start_address != bottom_address) {
 715       size_t fill_size = pointer_delta(start_address, bottom_address);
 716       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 717       increase_used(fill_size * HeapWordSize);
 718     }
 719   }
 720 }
 721 
 722 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) {
 723   assert_heap_not_locked_and_not_at_safepoint();
 724   assert(!is_humongous(word_size), "attempt_allocation() should not "
 725          "be called for humongous allocation requests");
 726 
 727   HeapWord* result = _allocator->attempt_allocation(word_size);
 728 
 729   if (result == NULL) {
 730     result = attempt_allocation_slow(word_size);
 731   }
 732   assert_heap_not_locked();
 733   if (result != NULL) {
 734     dirty_young_block(result, word_size);
 735   }
 736   return result;
 737 }
 738 
 739 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 740   assert(!is_init_completed(), "Expect to be called at JVM init time");
 741   assert(ranges != NULL, "MemRegion array NULL");
 742   assert(count != 0, "No MemRegions provided");
 743   MemRegion reserved = _hrm.reserved();
 744   HeapWord* prev_last_addr = NULL;
 745   HeapRegion* prev_last_region = NULL;
 746   size_t size_used = 0;
 747   size_t uncommitted_regions = 0;
 748 
 749   // For each Memregion, free the G1 regions that constitute it, and
 750   // notify mark-sweep that the range is no longer to be considered 'archive.'
 751   MutexLockerEx x(Heap_lock);
 752   for (size_t i = 0; i < count; i++) {
 753     HeapWord* start_address = ranges[i].start();
 754     HeapWord* last_address = ranges[i].last();
 755 
 756     assert(reserved.contains(start_address) && reserved.contains(last_address),
 757            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 758            p2i(start_address), p2i(last_address));
 759     assert(start_address > prev_last_addr,
 760            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 761            p2i(start_address), p2i(prev_last_addr));
 762     size_used += ranges[i].byte_size();
 763     prev_last_addr = last_address;
 764 
 765     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 766     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 767 
 768     // Check for ranges that start in the same G1 region in which the previous
 769     // range ended, and adjust the start address so we don't try to free
 770     // the same region again. If the current range is entirely within that
 771     // region, skip it.
 772     if (start_region == prev_last_region) {
 773       start_address = start_region->end();
 774       if (start_address > last_address) {
 775         continue;
 776       }
 777       start_region = _hrm.addr_to_region(start_address);
 778     }
 779     prev_last_region = last_region;
 780 
 781     // After verifying that each region was marked as an archive region by
 782     // alloc_archive_regions, set it free and empty and uncommit it.
 783     HeapRegion* curr_region = start_region;
 784     while (curr_region != NULL) {
 785       guarantee(curr_region->is_archive(),
 786                 "Expected archive region at index %u", curr_region->hrm_index());
 787       uint curr_index = curr_region->hrm_index();
 788       _old_set.remove(curr_region);
 789       curr_region->set_free();
 790       curr_region->set_top(curr_region->bottom());
 791       if (curr_region != last_region) {
 792         curr_region = _hrm.next_region_in_heap(curr_region);
 793       } else {
 794         curr_region = NULL;
 795       }
 796       _hrm.shrink_at(curr_index, 1);
 797       uncommitted_regions++;
 798     }
 799 
 800     // Notify mark-sweep that this is no longer an archive range.
 801     G1ArchiveAllocator::set_range_archive(ranges[i], false);
 802   }
 803 
 804   if (uncommitted_regions != 0) {
 805     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 806                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 807   }
 808   decrease_used(size_used);
 809 }
 810 
 811 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 812   ResourceMark rm; // For retrieving the thread names in log messages.
 813 
 814   // The structure of this method has a lot of similarities to
 815   // attempt_allocation_slow(). The reason these two were not merged
 816   // into a single one is that such a method would require several "if
 817   // allocation is not humongous do this, otherwise do that"
 818   // conditional paths which would obscure its flow. In fact, an early
 819   // version of this code did use a unified method which was harder to
 820   // follow and, as a result, it had subtle bugs that were hard to
 821   // track down. So keeping these two methods separate allows each to
 822   // be more readable. It will be good to keep these two in sync as
 823   // much as possible.
 824 
 825   assert_heap_not_locked_and_not_at_safepoint();
 826   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 827          "should only be called for humongous allocations");
 828 
 829   // Humongous objects can exhaust the heap quickly, so we should check if we
 830   // need to start a marking cycle at each humongous object allocation. We do
 831   // the check before we do the actual allocation. The reason for doing it
 832   // before the allocation is that we avoid having to keep track of the newly
 833   // allocated memory while we do a GC.
 834   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 835                                            word_size)) {
 836     collect(GCCause::_g1_humongous_allocation);
 837   }
 838 
 839   // We will loop until a) we manage to successfully perform the
 840   // allocation or b) we successfully schedule a collection which
 841   // fails to perform the allocation. b) is the only case when we'll
 842   // return NULL.
 843   HeapWord* result = NULL;
 844   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 845     bool should_try_gc;
 846     uint gc_count_before;
 847 
 848 
 849     {
 850       MutexLockerEx x(Heap_lock);
 851 
 852       // Given that humongous objects are not allocated in young
 853       // regions, we'll first try to do the allocation without doing a
 854       // collection hoping that there's enough space in the heap.
 855       result = humongous_obj_allocate(word_size);
 856       if (result != NULL) {
 857         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 858         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 859         return result;
 860       }
 861 
 862       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 863       // the GCLocker initiated GC has been performed and then retry. This includes
 864       // the case when the GC Locker is not active but has not been performed.
 865       should_try_gc = !GCLocker::needs_gc();
 866       // Read the GC count while still holding the Heap_lock.
 867       gc_count_before = total_collections();
 868     }
 869 
 870     if (should_try_gc) {
 871       bool succeeded;
 872       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 873                                    GCCause::_g1_humongous_allocation);
 874       if (result != NULL) {
 875         assert(succeeded, "only way to get back a non-NULL result");
 876         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 877                              Thread::current()->name(), p2i(result));
 878         return result;
 879       }
 880 
 881       if (succeeded) {
 882         // We successfully scheduled a collection which failed to allocate. No
 883         // point in trying to allocate further. We'll just return NULL.
 884         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 885                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 886         return NULL;
 887       }
 888       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 889                            Thread::current()->name(), word_size);
 890     } else {
 891       // Failed to schedule a collection.
 892       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 893         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 894                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 895         return NULL;
 896       }
 897       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 898       // The GCLocker is either active or the GCLocker initiated
 899       // GC has not yet been performed. Stall until it is and
 900       // then retry the allocation.
 901       GCLocker::stall_until_clear();
 902       gclocker_retry_count += 1;
 903     }
 904 
 905 
 906     // We can reach here if we were unsuccessful in scheduling a
 907     // collection (because another thread beat us to it) or if we were
 908     // stalled due to the GC locker. In either can we should retry the
 909     // allocation attempt in case another thread successfully
 910     // performed a collection and reclaimed enough space.
 911     // Humongous object allocation always needs a lock, so we wait for the retry
 912     // in the next iteration of the loop, unlike for the regular iteration case.
 913     // Give a warning if we seem to be looping forever.
 914 
 915     if ((QueuedAllocationWarningCount > 0) &&
 916         (try_count % QueuedAllocationWarningCount == 0)) {
 917       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 918                              Thread::current()->name(), try_count, word_size);
 919     }
 920   }
 921 
 922   ShouldNotReachHere();
 923   return NULL;
 924 }
 925 
 926 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 927                                                            bool expect_null_mutator_alloc_region) {
 928   assert_at_safepoint_on_vm_thread();
 929   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 930          "the current alloc region was unexpectedly found to be non-NULL");
 931 
 932   if (!is_humongous(word_size)) {
 933     return _allocator->attempt_allocation_locked(word_size);
 934   } else {
 935     HeapWord* result = humongous_obj_allocate(word_size);
 936     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
 937       collector_state()->set_initiate_conc_mark_if_possible(true);
 938     }
 939     return result;
 940   }
 941 
 942   ShouldNotReachHere();
 943 }
 944 
 945 class PostCompactionPrinterClosure: public HeapRegionClosure {
 946 private:
 947   G1HRPrinter* _hr_printer;
 948 public:
 949   bool do_heap_region(HeapRegion* hr) {
 950     assert(!hr->is_young(), "not expecting to find young regions");
 951     _hr_printer->post_compaction(hr);
 952     return false;
 953   }
 954 
 955   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 956     : _hr_printer(hr_printer) { }
 957 };
 958 
 959 void G1CollectedHeap::print_hrm_post_compaction() {
 960   if (_hr_printer.is_active()) {
 961     PostCompactionPrinterClosure cl(hr_printer());
 962     heap_region_iterate(&cl);
 963   }
 964 }
 965 
 966 void G1CollectedHeap::abort_concurrent_cycle() {
 967   // If we start the compaction before the CM threads finish
 968   // scanning the root regions we might trip them over as we'll
 969   // be moving objects / updating references. So let's wait until
 970   // they are done. By telling them to abort, they should complete
 971   // early.
 972   _cm->root_regions()->abort();
 973   _cm->root_regions()->wait_until_scan_finished();
 974 
 975   // Disable discovery and empty the discovered lists
 976   // for the CM ref processor.
 977   ref_processor_cm()->disable_discovery();
 978   ref_processor_cm()->abandon_partial_discovery();
 979   ref_processor_cm()->verify_no_references_recorded();
 980 
 981   // Abandon current iterations of concurrent marking and concurrent
 982   // refinement, if any are in progress.
 983   concurrent_mark()->concurrent_cycle_abort();
 984 }
 985 
 986 void G1CollectedHeap::prepare_heap_for_full_collection() {
 987   // Make sure we'll choose a new allocation region afterwards.
 988   _allocator->release_mutator_alloc_region();
 989   _allocator->abandon_gc_alloc_regions();
 990   g1_rem_set()->cleanupHRRS();
 991 
 992   // We may have added regions to the current incremental collection
 993   // set between the last GC or pause and now. We need to clear the
 994   // incremental collection set and then start rebuilding it afresh
 995   // after this full GC.
 996   abandon_collection_set(collection_set());
 997 
 998   tear_down_region_sets(false /* free_list_only */);
 999 }
1000 
1001 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1002   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1003   assert(used() == recalculate_used(), "Should be equal");
1004   _verifier->verify_region_sets_optional();
1005   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1006   _verifier->check_bitmaps("Full GC Start");
1007 }
1008 
1009 void G1CollectedHeap::prepare_heap_for_mutators() {
1010   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1011   ClassLoaderDataGraph::purge();
1012   MetaspaceUtils::verify_metrics();
1013 
1014   // Prepare heap for normal collections.
1015   assert(num_free_regions() == 0, "we should not have added any free regions");
1016   rebuild_region_sets(false /* free_list_only */);
1017   abort_refinement();
1018   resize_if_necessary_after_full_collection();
1019 
1020   // Rebuild the strong code root lists for each region
1021   rebuild_strong_code_roots();
1022 
1023   // Start a new incremental collection set for the next pause
1024   start_new_collection_set();
1025 
1026   _allocator->init_mutator_alloc_region();
1027 
1028   // Post collection state updates.
1029   MetaspaceGC::compute_new_size();
1030 }
1031 
1032 void G1CollectedHeap::abort_refinement() {
1033   if (_hot_card_cache->use_cache()) {
1034     _hot_card_cache->reset_hot_cache();
1035   }
1036 
1037   // Discard all remembered set updates.
1038   JavaThread::dirty_card_queue_set().abandon_logs();
1039   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1040 }
1041 
1042 void G1CollectedHeap::verify_after_full_collection() {
1043   _hrm.verify_optional();
1044   _verifier->verify_region_sets_optional();
1045   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1046   // Clear the previous marking bitmap, if needed for bitmap verification.
1047   // Note we cannot do this when we clear the next marking bitmap in
1048   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1049   // objects marked during a full GC against the previous bitmap.
1050   // But we need to clear it before calling check_bitmaps below since
1051   // the full GC has compacted objects and updated TAMS but not updated
1052   // the prev bitmap.
1053   if (G1VerifyBitmaps) {
1054     GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1055     _cm->clear_prev_bitmap(workers());
1056   }
1057   _verifier->check_bitmaps("Full GC End");
1058 
1059   // At this point there should be no regions in the
1060   // entire heap tagged as young.
1061   assert(check_young_list_empty(), "young list should be empty at this point");
1062 
1063   // Note: since we've just done a full GC, concurrent
1064   // marking is no longer active. Therefore we need not
1065   // re-enable reference discovery for the CM ref processor.
1066   // That will be done at the start of the next marking cycle.
1067   // We also know that the STW processor should no longer
1068   // discover any new references.
1069   assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1070   assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1071   ref_processor_stw()->verify_no_references_recorded();
1072   ref_processor_cm()->verify_no_references_recorded();
1073 }
1074 
1075 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1076   // Post collection logging.
1077   // We should do this after we potentially resize the heap so
1078   // that all the COMMIT / UNCOMMIT events are generated before
1079   // the compaction events.
1080   print_hrm_post_compaction();
1081   heap_transition->print();
1082   print_heap_after_gc();
1083   print_heap_regions();
1084 #ifdef TRACESPINNING
1085   ParallelTaskTerminator::print_termination_counts();
1086 #endif
1087 }
1088 
1089 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1090                                          bool clear_all_soft_refs) {
1091   assert_at_safepoint_on_vm_thread();
1092 
1093   if (GCLocker::check_active_before_gc()) {
1094     // Full GC was not completed.
1095     return false;
1096   }
1097 
1098   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1099       soft_ref_policy()->should_clear_all_soft_refs();
1100 
1101   G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1102   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1103 
1104   collector.prepare_collection();
1105   collector.collect();
1106   collector.complete_collection();
1107 
1108   // Full collection was successfully completed.
1109   return true;
1110 }
1111 
1112 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1113   // Currently, there is no facility in the do_full_collection(bool) API to notify
1114   // the caller that the collection did not succeed (e.g., because it was locked
1115   // out by the GC locker). So, right now, we'll ignore the return value.
1116   bool dummy = do_full_collection(true,                /* explicit_gc */
1117                                   clear_all_soft_refs);
1118 }
1119 
1120 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1121   // Capacity, free and used after the GC counted as full regions to
1122   // include the waste in the following calculations.
1123   const size_t capacity_after_gc = capacity();
1124   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1125 
1126   // This is enforced in arguments.cpp.
1127   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1128          "otherwise the code below doesn't make sense");
1129 
1130   // We don't have floating point command-line arguments
1131   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1132   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1133   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1134   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1135 
1136   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1137   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1138 
1139   // We have to be careful here as these two calculations can overflow
1140   // 32-bit size_t's.
1141   double used_after_gc_d = (double) used_after_gc;
1142   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1143   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1144 
1145   // Let's make sure that they are both under the max heap size, which
1146   // by default will make them fit into a size_t.
1147   double desired_capacity_upper_bound = (double) max_heap_size;
1148   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1149                                     desired_capacity_upper_bound);
1150   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1151                                     desired_capacity_upper_bound);
1152 
1153   // We can now safely turn them into size_t's.
1154   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1155   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1156 
1157   // This assert only makes sense here, before we adjust them
1158   // with respect to the min and max heap size.
1159   assert(minimum_desired_capacity <= maximum_desired_capacity,
1160          "minimum_desired_capacity = " SIZE_FORMAT ", "
1161          "maximum_desired_capacity = " SIZE_FORMAT,
1162          minimum_desired_capacity, maximum_desired_capacity);
1163 
1164   // Should not be greater than the heap max size. No need to adjust
1165   // it with respect to the heap min size as it's a lower bound (i.e.,
1166   // we'll try to make the capacity larger than it, not smaller).
1167   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1168   // Should not be less than the heap min size. No need to adjust it
1169   // with respect to the heap max size as it's an upper bound (i.e.,
1170   // we'll try to make the capacity smaller than it, not greater).
1171   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1172 
1173   if (capacity_after_gc < minimum_desired_capacity) {
1174     // Don't expand unless it's significant
1175     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1176 
1177     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1178                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1179                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1180                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1181 
1182     expand(expand_bytes, _workers);
1183 
1184     // No expansion, now see if we want to shrink
1185   } else if (capacity_after_gc > maximum_desired_capacity) {
1186     // Capacity too large, compute shrinking size
1187     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1188 
1189     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1190                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1191                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1192                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1193 
1194     shrink(shrink_bytes);
1195   }
1196 }
1197 
1198 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1199                                                             bool do_gc,
1200                                                             bool clear_all_soft_refs,
1201                                                             bool expect_null_mutator_alloc_region,
1202                                                             bool* gc_succeeded) {
1203   *gc_succeeded = true;
1204   // Let's attempt the allocation first.
1205   HeapWord* result =
1206     attempt_allocation_at_safepoint(word_size,
1207                                     expect_null_mutator_alloc_region);
1208   if (result != NULL) {
1209     return result;
1210   }
1211 
1212   // In a G1 heap, we're supposed to keep allocation from failing by
1213   // incremental pauses.  Therefore, at least for now, we'll favor
1214   // expansion over collection.  (This might change in the future if we can
1215   // do something smarter than full collection to satisfy a failed alloc.)
1216   result = expand_and_allocate(word_size);
1217   if (result != NULL) {
1218     return result;
1219   }
1220 
1221   if (do_gc) {
1222     // Expansion didn't work, we'll try to do a Full GC.
1223     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1224                                        clear_all_soft_refs);
1225   }
1226 
1227   return NULL;
1228 }
1229 
1230 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1231                                                      bool* succeeded) {
1232   assert_at_safepoint_on_vm_thread();
1233 
1234   // Attempts to allocate followed by Full GC.
1235   HeapWord* result =
1236     satisfy_failed_allocation_helper(word_size,
1237                                      true,  /* do_gc */
1238                                      false, /* clear_all_soft_refs */
1239                                      false, /* expect_null_mutator_alloc_region */
1240                                      succeeded);
1241 
1242   if (result != NULL || !*succeeded) {
1243     return result;
1244   }
1245 
1246   // Attempts to allocate followed by Full GC that will collect all soft references.
1247   result = satisfy_failed_allocation_helper(word_size,
1248                                             true, /* do_gc */
1249                                             true, /* clear_all_soft_refs */
1250                                             true, /* expect_null_mutator_alloc_region */
1251                                             succeeded);
1252 
1253   if (result != NULL || !*succeeded) {
1254     return result;
1255   }
1256 
1257   // Attempts to allocate, no GC
1258   result = satisfy_failed_allocation_helper(word_size,
1259                                             false, /* do_gc */
1260                                             false, /* clear_all_soft_refs */
1261                                             true,  /* expect_null_mutator_alloc_region */
1262                                             succeeded);
1263 
1264   if (result != NULL) {
1265     return result;
1266   }
1267 
1268   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1269          "Flag should have been handled and cleared prior to this point");
1270 
1271   // What else?  We might try synchronous finalization later.  If the total
1272   // space available is large enough for the allocation, then a more
1273   // complete compaction phase than we've tried so far might be
1274   // appropriate.
1275   return NULL;
1276 }
1277 
1278 // Attempting to expand the heap sufficiently
1279 // to support an allocation of the given "word_size".  If
1280 // successful, perform the allocation and return the address of the
1281 // allocated block, or else "NULL".
1282 
1283 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1284   assert_at_safepoint_on_vm_thread();
1285 
1286   _verifier->verify_region_sets_optional();
1287 
1288   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1289   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1290                             word_size * HeapWordSize);
1291 
1292 
1293   if (expand(expand_bytes, _workers)) {
1294     _hrm.verify_optional();
1295     _verifier->verify_region_sets_optional();
1296     return attempt_allocation_at_safepoint(word_size,
1297                                            false /* expect_null_mutator_alloc_region */);
1298   }
1299   return NULL;
1300 }
1301 
1302 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1303   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1304   aligned_expand_bytes = align_up(aligned_expand_bytes,
1305                                        HeapRegion::GrainBytes);
1306 
1307   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1308                             expand_bytes, aligned_expand_bytes);
1309 
1310   if (is_maximal_no_gc()) {
1311     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1312     return false;
1313   }
1314 
1315   double expand_heap_start_time_sec = os::elapsedTime();
1316   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1317   assert(regions_to_expand > 0, "Must expand by at least one region");
1318 
1319   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1320   if (expand_time_ms != NULL) {
1321     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1322   }
1323 
1324   if (expanded_by > 0) {
1325     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1326     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1327     g1_policy()->record_new_heap_size(num_regions());
1328   } else {
1329     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1330 
1331     // The expansion of the virtual storage space was unsuccessful.
1332     // Let's see if it was because we ran out of swap.
1333     if (G1ExitOnExpansionFailure &&
1334         _hrm.available() >= regions_to_expand) {
1335       // We had head room...
1336       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1337     }
1338   }
1339   return regions_to_expand > 0;
1340 }
1341 
1342 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1343   size_t aligned_shrink_bytes =
1344     ReservedSpace::page_align_size_down(shrink_bytes);
1345   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1346                                          HeapRegion::GrainBytes);
1347   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1348 
1349   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1350   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1351 
1352 
1353   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",
1354                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1355   if (num_regions_removed > 0) {
1356     g1_policy()->record_new_heap_size(num_regions());
1357   } else {
1358     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1359   }
1360 }
1361 
1362 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1363   _verifier->verify_region_sets_optional();
1364 
1365   // We should only reach here at the end of a Full GC which means we
1366   // should not not be holding to any GC alloc regions. The method
1367   // below will make sure of that and do any remaining clean up.
1368   _allocator->abandon_gc_alloc_regions();
1369 
1370   // Instead of tearing down / rebuilding the free lists here, we
1371   // could instead use the remove_all_pending() method on free_list to
1372   // remove only the ones that we need to remove.
1373   tear_down_region_sets(true /* free_list_only */);
1374   shrink_helper(shrink_bytes);
1375   rebuild_region_sets(true /* free_list_only */);
1376 
1377   _hrm.verify_optional();
1378   _verifier->verify_region_sets_optional();
1379 }
1380 
1381 // Public methods.
1382 
1383 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1384   CollectedHeap(),
1385   _young_gen_sampling_thread(NULL),
1386   _collector_policy(collector_policy),
1387   _soft_ref_policy(),
1388   _card_table(NULL),
1389   _memory_manager("G1 Young Generation", "end of minor GC"),
1390   _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1391   _eden_pool(NULL),
1392   _survivor_pool(NULL),
1393   _old_pool(NULL),
1394   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1395   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1396   _g1_policy(new G1Policy(_gc_timer_stw)),
1397   _collection_set(this, _g1_policy),
1398   _dirty_card_queue_set(false),
1399   _is_alive_closure_cm(this),
1400   _is_alive_closure_stw(this),
1401   _ref_processor_cm(NULL),
1402   _ref_processor_stw(NULL),
1403   _bot(NULL),
1404   _hot_card_cache(NULL),
1405   _g1_rem_set(NULL),
1406   _cr(NULL),
1407   _g1mm(NULL),
1408   _preserved_marks_set(true /* in_c_heap */),
1409   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1410   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1411   _humongous_reclaim_candidates(),
1412   _has_humongous_reclaim_candidates(false),
1413   _archive_allocator(NULL),
1414   _summary_bytes_used(0),
1415   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1416   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1417   _expand_heap_after_alloc_failure(true),
1418   _old_marking_cycles_started(0),
1419   _old_marking_cycles_completed(0),
1420   _in_cset_fast_test() {
1421 
1422   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1423                           /* are_GC_task_threads */true,
1424                           /* are_ConcurrentGC_threads */false);
1425   _workers->initialize_workers();
1426   _verifier = new G1HeapVerifier(this);
1427 
1428   _allocator = new G1Allocator(this);
1429 
1430   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1431 
1432   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1433 
1434   // Override the default _filler_array_max_size so that no humongous filler
1435   // objects are created.
1436   _filler_array_max_size = _humongous_object_threshold_in_words;
1437 
1438   uint n_queues = ParallelGCThreads;
1439   _task_queues = new RefToScanQueueSet(n_queues);
1440 
1441   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1442 
1443   for (uint i = 0; i < n_queues; i++) {
1444     RefToScanQueue* q = new RefToScanQueue();
1445     q->initialize();
1446     _task_queues->register_queue(i, q);
1447     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1448   }
1449 
1450   // Initialize the G1EvacuationFailureALot counters and flags.
1451   NOT_PRODUCT(reset_evacuation_should_fail();)
1452 
1453   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1454 }
1455 
1456 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1457                                                                  size_t size,
1458                                                                  size_t translation_factor) {
1459   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1460   // Allocate a new reserved space, preferring to use large pages.
1461   ReservedSpace rs(size, preferred_page_size);
1462   G1RegionToSpaceMapper* result  =
1463     G1RegionToSpaceMapper::create_mapper(rs,
1464                                          size,
1465                                          rs.alignment(),
1466                                          HeapRegion::GrainBytes,
1467                                          translation_factor,
1468                                          mtGC);
1469 
1470   os::trace_page_sizes_for_requested_size(description,
1471                                           size,
1472                                           preferred_page_size,
1473                                           rs.alignment(),
1474                                           rs.base(),
1475                                           rs.size());
1476 
1477   return result;
1478 }
1479 
1480 jint G1CollectedHeap::initialize_concurrent_refinement() {
1481   jint ecode = JNI_OK;
1482   _cr = G1ConcurrentRefine::create(&ecode);
1483   return ecode;
1484 }
1485 
1486 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1487   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1488   if (_young_gen_sampling_thread->osthread() == NULL) {
1489     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1490     return JNI_ENOMEM;
1491   }
1492   return JNI_OK;
1493 }
1494 
1495 jint G1CollectedHeap::initialize() {
1496   os::enable_vtime();
1497 
1498   // Necessary to satisfy locking discipline assertions.
1499 
1500   MutexLocker x(Heap_lock);
1501 
1502   // While there are no constraints in the GC code that HeapWordSize
1503   // be any particular value, there are multiple other areas in the
1504   // system which believe this to be true (e.g. oop->object_size in some
1505   // cases incorrectly returns the size in wordSize units rather than
1506   // HeapWordSize).
1507   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1508 
1509   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1510   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1511   size_t heap_alignment = collector_policy()->heap_alignment();
1512 
1513   // Ensure that the sizes are properly aligned.
1514   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1515   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1516   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1517 
1518   // Reserve the maximum.
1519 
1520   // When compressed oops are enabled, the preferred heap base
1521   // is calculated by subtracting the requested size from the
1522   // 32Gb boundary and using the result as the base address for
1523   // heap reservation. If the requested size is not aligned to
1524   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1525   // into the ReservedHeapSpace constructor) then the actual
1526   // base of the reserved heap may end up differing from the
1527   // address that was requested (i.e. the preferred heap base).
1528   // If this happens then we could end up using a non-optimal
1529   // compressed oops mode.
1530 
1531   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1532                                                  heap_alignment);
1533 
1534   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1535 
1536   // Create the barrier set for the entire reserved region.
1537   G1CardTable* ct = new G1CardTable(reserved_region());
1538   ct->initialize();
1539   G1BarrierSet* bs = new G1BarrierSet(ct);
1540   bs->initialize();
1541   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1542   set_barrier_set(bs);
1543   _card_table = ct;
1544 
1545   // Create the hot card cache.
1546   _hot_card_cache = new G1HotCardCache(this);
1547 
1548   // Carve out the G1 part of the heap.
1549   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1550   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1551   G1RegionToSpaceMapper* heap_storage =
1552     G1RegionToSpaceMapper::create_mapper(g1_rs,
1553                                          g1_rs.size(),
1554                                          page_size,
1555                                          HeapRegion::GrainBytes,
1556                                          1,
1557                                          mtJavaHeap);
1558   os::trace_page_sizes("Heap",
1559                        collector_policy()->min_heap_byte_size(),
1560                        max_byte_size,
1561                        page_size,
1562                        heap_rs.base(),
1563                        heap_rs.size());
1564   heap_storage->set_mapping_changed_listener(&_listener);
1565 
1566   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1567   G1RegionToSpaceMapper* bot_storage =
1568     create_aux_memory_mapper("Block Offset Table",
1569                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1570                              G1BlockOffsetTable::heap_map_factor());
1571 
1572   G1RegionToSpaceMapper* cardtable_storage =
1573     create_aux_memory_mapper("Card Table",
1574                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1575                              G1CardTable::heap_map_factor());
1576 
1577   G1RegionToSpaceMapper* card_counts_storage =
1578     create_aux_memory_mapper("Card Counts Table",
1579                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1580                              G1CardCounts::heap_map_factor());
1581 
1582   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1583   G1RegionToSpaceMapper* prev_bitmap_storage =
1584     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1585   G1RegionToSpaceMapper* next_bitmap_storage =
1586     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1587 
1588   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1589   _card_table->initialize(cardtable_storage);
1590   // Do later initialization work for concurrent refinement.
1591   _hot_card_cache->initialize(card_counts_storage);
1592 
1593   // 6843694 - ensure that the maximum region index can fit
1594   // in the remembered set structures.
1595   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1596   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1597 
1598   // Also create a G1 rem set.
1599   _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1600   _g1_rem_set->initialize(max_capacity(), max_regions());
1601 
1602   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1603   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1604   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1605             "too many cards per region");
1606 
1607   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1608 
1609   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1610 
1611   {
1612     HeapWord* start = _hrm.reserved().start();
1613     HeapWord* end = _hrm.reserved().end();
1614     size_t granularity = HeapRegion::GrainBytes;
1615 
1616     _in_cset_fast_test.initialize(start, end, granularity);
1617     _humongous_reclaim_candidates.initialize(start, end, granularity);
1618   }
1619 
1620   // Create the G1ConcurrentMark data structure and thread.
1621   // (Must do this late, so that "max_regions" is defined.)
1622   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1623   if (_cm == NULL || !_cm->completed_initialization()) {
1624     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1625     return JNI_ENOMEM;
1626   }
1627   _cm_thread = _cm->cm_thread();
1628 
1629   // Now expand into the initial heap size.
1630   if (!expand(init_byte_size, _workers)) {
1631     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1632     return JNI_ENOMEM;
1633   }
1634 
1635   // Perform any initialization actions delegated to the policy.
1636   g1_policy()->init(this, &_collection_set);
1637 
1638   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1639                                                SATB_Q_FL_lock,
1640                                                G1SATBProcessCompletedThreshold,
1641                                                Shared_SATB_Q_lock);
1642 
1643   jint ecode = initialize_concurrent_refinement();
1644   if (ecode != JNI_OK) {
1645     return ecode;
1646   }
1647 
1648   ecode = initialize_young_gen_sampling_thread();
1649   if (ecode != JNI_OK) {
1650     return ecode;
1651   }
1652 
1653   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1654                                                 DirtyCardQ_FL_lock,
1655                                                 (int)concurrent_refine()->yellow_zone(),
1656                                                 (int)concurrent_refine()->red_zone(),
1657                                                 Shared_DirtyCardQ_lock,
1658                                                 NULL,  // fl_owner
1659                                                 true); // init_free_ids
1660 
1661   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1662                                     DirtyCardQ_FL_lock,
1663                                     -1, // never trigger processing
1664                                     -1, // no limit on length
1665                                     Shared_DirtyCardQ_lock,
1666                                     &JavaThread::dirty_card_queue_set());
1667 
1668   // Here we allocate the dummy HeapRegion that is required by the
1669   // G1AllocRegion class.
1670   HeapRegion* dummy_region = _hrm.get_dummy_region();
1671 
1672   // We'll re-use the same region whether the alloc region will
1673   // require BOT updates or not and, if it doesn't, then a non-young
1674   // region will complain that it cannot support allocations without
1675   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1676   dummy_region->set_eden();
1677   // Make sure it's full.
1678   dummy_region->set_top(dummy_region->end());
1679   G1AllocRegion::setup(this, dummy_region);
1680 
1681   _allocator->init_mutator_alloc_region();
1682 
1683   // Do create of the monitoring and management support so that
1684   // values in the heap have been properly initialized.
1685   _g1mm = new G1MonitoringSupport(this);
1686 
1687   G1StringDedup::initialize();
1688 
1689   _preserved_marks_set.init(ParallelGCThreads);
1690 
1691   _collection_set.initialize(max_regions());
1692 
1693   return JNI_OK;
1694 }
1695 
1696 void G1CollectedHeap::initialize_serviceability() {
1697   _eden_pool = new G1EdenPool(this);
1698   _survivor_pool = new G1SurvivorPool(this);
1699   _old_pool = new G1OldGenPool(this);
1700 
1701   _full_gc_memory_manager.add_pool(_eden_pool);
1702   _full_gc_memory_manager.add_pool(_survivor_pool);
1703   _full_gc_memory_manager.add_pool(_old_pool);
1704 
1705   _memory_manager.add_pool(_eden_pool);
1706   _memory_manager.add_pool(_survivor_pool);
1707 
1708 }
1709 
1710 void G1CollectedHeap::stop() {
1711   // Stop all concurrent threads. We do this to make sure these threads
1712   // do not continue to execute and access resources (e.g. logging)
1713   // that are destroyed during shutdown.
1714   _cr->stop();
1715   _young_gen_sampling_thread->stop();
1716   _cm_thread->stop();
1717   if (G1StringDedup::is_enabled()) {
1718     G1StringDedup::stop();
1719   }
1720 }
1721 
1722 void G1CollectedHeap::safepoint_synchronize_begin() {
1723   SuspendibleThreadSet::synchronize();
1724 }
1725 
1726 void G1CollectedHeap::safepoint_synchronize_end() {
1727   SuspendibleThreadSet::desynchronize();
1728 }
1729 
1730 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1731   return HeapRegion::max_region_size();
1732 }
1733 
1734 void G1CollectedHeap::post_initialize() {
1735   CollectedHeap::post_initialize();
1736   ref_processing_init();
1737 }
1738 
1739 void G1CollectedHeap::ref_processing_init() {
1740   // Reference processing in G1 currently works as follows:
1741   //
1742   // * There are two reference processor instances. One is
1743   //   used to record and process discovered references
1744   //   during concurrent marking; the other is used to
1745   //   record and process references during STW pauses
1746   //   (both full and incremental).
1747   // * Both ref processors need to 'span' the entire heap as
1748   //   the regions in the collection set may be dotted around.
1749   //
1750   // * For the concurrent marking ref processor:
1751   //   * Reference discovery is enabled at initial marking.
1752   //   * Reference discovery is disabled and the discovered
1753   //     references processed etc during remarking.
1754   //   * Reference discovery is MT (see below).
1755   //   * Reference discovery requires a barrier (see below).
1756   //   * Reference processing may or may not be MT
1757   //     (depending on the value of ParallelRefProcEnabled
1758   //     and ParallelGCThreads).
1759   //   * A full GC disables reference discovery by the CM
1760   //     ref processor and abandons any entries on it's
1761   //     discovered lists.
1762   //
1763   // * For the STW processor:
1764   //   * Non MT discovery is enabled at the start of a full GC.
1765   //   * Processing and enqueueing during a full GC is non-MT.
1766   //   * During a full GC, references are processed after marking.
1767   //
1768   //   * Discovery (may or may not be MT) is enabled at the start
1769   //     of an incremental evacuation pause.
1770   //   * References are processed near the end of a STW evacuation pause.
1771   //   * For both types of GC:
1772   //     * Discovery is atomic - i.e. not concurrent.
1773   //     * Reference discovery will not need a barrier.
1774 
1775   MemRegion mr = reserved_region();
1776 
1777   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1778 
1779   // Concurrent Mark ref processor
1780   _ref_processor_cm =
1781     new ReferenceProcessor(mr,    // span
1782                            mt_processing,
1783                                 // mt processing
1784                            ParallelGCThreads,
1785                                 // degree of mt processing
1786                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1787                                 // mt discovery
1788                            MAX2(ParallelGCThreads, ConcGCThreads),
1789                                 // degree of mt discovery
1790                            false,
1791                                 // Reference discovery is not atomic
1792                            &_is_alive_closure_cm);
1793                                 // is alive closure
1794                                 // (for efficiency/performance)
1795 
1796   // STW ref processor
1797   _ref_processor_stw =
1798     new ReferenceProcessor(mr,    // span
1799                            mt_processing,
1800                                 // mt processing
1801                            ParallelGCThreads,
1802                                 // degree of mt processing
1803                            (ParallelGCThreads > 1),
1804                                 // mt discovery
1805                            ParallelGCThreads,
1806                                 // degree of mt discovery
1807                            true,
1808                                 // Reference discovery is atomic
1809                            &_is_alive_closure_stw);
1810                                 // is alive closure
1811                                 // (for efficiency/performance)
1812 }
1813 
1814 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1815   return _collector_policy;
1816 }
1817 
1818 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1819   return &_soft_ref_policy;
1820 }
1821 
1822 size_t G1CollectedHeap::capacity() const {
1823   return _hrm.length() * HeapRegion::GrainBytes;
1824 }
1825 
1826 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1827   return _hrm.total_free_bytes();
1828 }
1829 
1830 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1831   _hot_card_cache->drain(cl, worker_i);
1832 }
1833 
1834 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1835   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1836   size_t n_completed_buffers = 0;
1837   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1838     n_completed_buffers++;
1839   }
1840   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1841   dcqs.clear_n_completed_buffers();
1842   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1843 }
1844 
1845 // Computes the sum of the storage used by the various regions.
1846 size_t G1CollectedHeap::used() const {
1847   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1848   if (_archive_allocator != NULL) {
1849     result += _archive_allocator->used();
1850   }
1851   return result;
1852 }
1853 
1854 size_t G1CollectedHeap::used_unlocked() const {
1855   return _summary_bytes_used;
1856 }
1857 
1858 class SumUsedClosure: public HeapRegionClosure {
1859   size_t _used;
1860 public:
1861   SumUsedClosure() : _used(0) {}
1862   bool do_heap_region(HeapRegion* r) {
1863     _used += r->used();
1864     return false;
1865   }
1866   size_t result() { return _used; }
1867 };
1868 
1869 size_t G1CollectedHeap::recalculate_used() const {
1870   double recalculate_used_start = os::elapsedTime();
1871 
1872   SumUsedClosure blk;
1873   heap_region_iterate(&blk);
1874 
1875   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1876   return blk.result();
1877 }
1878 
1879 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1880   switch (cause) {
1881     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1882     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1883     case GCCause::_wb_conc_mark:                        return true;
1884     default :                                           return false;
1885   }
1886 }
1887 
1888 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1889   switch (cause) {
1890     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
1891     case GCCause::_g1_humongous_allocation: return true;
1892     default:                                return is_user_requested_concurrent_full_gc(cause);
1893   }
1894 }
1895 
1896 #ifndef PRODUCT
1897 void G1CollectedHeap::allocate_dummy_regions() {
1898   // Let's fill up most of the region
1899   size_t word_size = HeapRegion::GrainWords - 1024;
1900   // And as a result the region we'll allocate will be humongous.
1901   guarantee(is_humongous(word_size), "sanity");
1902 
1903   // _filler_array_max_size is set to humongous object threshold
1904   // but temporarily change it to use CollectedHeap::fill_with_object().
1905   SizeTFlagSetting fs(_filler_array_max_size, word_size);
1906 
1907   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1908     // Let's use the existing mechanism for the allocation
1909     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1910     if (dummy_obj != NULL) {
1911       MemRegion mr(dummy_obj, word_size);
1912       CollectedHeap::fill_with_object(mr);
1913     } else {
1914       // If we can't allocate once, we probably cannot allocate
1915       // again. Let's get out of the loop.
1916       break;
1917     }
1918   }
1919 }
1920 #endif // !PRODUCT
1921 
1922 void G1CollectedHeap::increment_old_marking_cycles_started() {
1923   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1924          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1925          "Wrong marking cycle count (started: %d, completed: %d)",
1926          _old_marking_cycles_started, _old_marking_cycles_completed);
1927 
1928   _old_marking_cycles_started++;
1929 }
1930 
1931 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
1932   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
1933 
1934   // We assume that if concurrent == true, then the caller is a
1935   // concurrent thread that was joined the Suspendible Thread
1936   // Set. If there's ever a cheap way to check this, we should add an
1937   // assert here.
1938 
1939   // Given that this method is called at the end of a Full GC or of a
1940   // concurrent cycle, and those can be nested (i.e., a Full GC can
1941   // interrupt a concurrent cycle), the number of full collections
1942   // completed should be either one (in the case where there was no
1943   // nesting) or two (when a Full GC interrupted a concurrent cycle)
1944   // behind the number of full collections started.
1945 
1946   // This is the case for the inner caller, i.e. a Full GC.
1947   assert(concurrent ||
1948          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1949          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1950          "for inner caller (Full GC): _old_marking_cycles_started = %u "
1951          "is inconsistent with _old_marking_cycles_completed = %u",
1952          _old_marking_cycles_started, _old_marking_cycles_completed);
1953 
1954   // This is the case for the outer caller, i.e. the concurrent cycle.
1955   assert(!concurrent ||
1956          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1957          "for outer caller (concurrent cycle): "
1958          "_old_marking_cycles_started = %u "
1959          "is inconsistent with _old_marking_cycles_completed = %u",
1960          _old_marking_cycles_started, _old_marking_cycles_completed);
1961 
1962   _old_marking_cycles_completed += 1;
1963 
1964   // We need to clear the "in_progress" flag in the CM thread before
1965   // we wake up any waiters (especially when ExplicitInvokesConcurrent
1966   // is set) so that if a waiter requests another System.gc() it doesn't
1967   // incorrectly see that a marking cycle is still in progress.
1968   if (concurrent) {
1969     _cm_thread->set_idle();
1970   }
1971 
1972   // This notify_all() will ensure that a thread that called
1973   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
1974   // and it's waiting for a full GC to finish will be woken up. It is
1975   // waiting in VM_G1CollectForAllocation::doit_epilogue().
1976   FullGCCount_lock->notify_all();
1977 }
1978 
1979 void G1CollectedHeap::collect(GCCause::Cause cause) {
1980   assert_heap_not_locked();
1981 
1982   uint gc_count_before;
1983   uint old_marking_count_before;
1984   uint full_gc_count_before;
1985   bool retry_gc;
1986 
1987   do {
1988     retry_gc = false;
1989 
1990     {
1991       MutexLocker ml(Heap_lock);
1992 
1993       // Read the GC count while holding the Heap_lock
1994       gc_count_before = total_collections();
1995       full_gc_count_before = total_full_collections();
1996       old_marking_count_before = _old_marking_cycles_started;
1997     }
1998 
1999     if (should_do_concurrent_full_gc(cause)) {
2000       // Schedule an initial-mark evacuation pause that will start a
2001       // concurrent cycle. We're setting word_size to 0 which means that
2002       // we are not requesting a post-GC allocation.
2003       VM_G1CollectForAllocation op(0,     /* word_size */
2004                                    gc_count_before,
2005                                    cause,
2006                                    true,  /* should_initiate_conc_mark */
2007                                    g1_policy()->max_pause_time_ms());
2008       VMThread::execute(&op);
2009       if (!op.pause_succeeded()) {
2010         if (old_marking_count_before == _old_marking_cycles_started) {
2011           retry_gc = op.should_retry_gc();
2012         } else {
2013           // A Full GC happened while we were trying to schedule the
2014           // initial-mark GC. No point in starting a new cycle given
2015           // that the whole heap was collected anyway.
2016         }
2017 
2018         if (retry_gc) {
2019           if (GCLocker::is_active_and_needs_gc()) {
2020             GCLocker::stall_until_clear();
2021           }
2022         }
2023       }
2024     } else {
2025       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2026           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2027 
2028         // Schedule a standard evacuation pause. We're setting word_size
2029         // to 0 which means that we are not requesting a post-GC allocation.
2030         VM_G1CollectForAllocation op(0,     /* word_size */
2031                                      gc_count_before,
2032                                      cause,
2033                                      false, /* should_initiate_conc_mark */
2034                                      g1_policy()->max_pause_time_ms());
2035         VMThread::execute(&op);
2036       } else {
2037         // Schedule a Full GC.
2038         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2039         VMThread::execute(&op);
2040       }
2041     }
2042   } while (retry_gc);
2043 }
2044 
2045 bool G1CollectedHeap::is_in(const void* p) const {
2046   if (_hrm.reserved().contains(p)) {
2047     // Given that we know that p is in the reserved space,
2048     // heap_region_containing() should successfully
2049     // return the containing region.
2050     HeapRegion* hr = heap_region_containing(p);
2051     return hr->is_in(p);
2052   } else {
2053     return false;
2054   }
2055 }
2056 
2057 #ifdef ASSERT
2058 bool G1CollectedHeap::is_in_exact(const void* p) const {
2059   bool contains = reserved_region().contains(p);
2060   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2061   if (contains && available) {
2062     return true;
2063   } else {
2064     return false;
2065   }
2066 }
2067 #endif
2068 
2069 // Iteration functions.
2070 
2071 // Iterates an ObjectClosure over all objects within a HeapRegion.
2072 
2073 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2074   ObjectClosure* _cl;
2075 public:
2076   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2077   bool do_heap_region(HeapRegion* r) {
2078     if (!r->is_continues_humongous()) {
2079       r->object_iterate(_cl);
2080     }
2081     return false;
2082   }
2083 };
2084 
2085 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2086   IterateObjectClosureRegionClosure blk(cl);
2087   heap_region_iterate(&blk);
2088 }
2089 
2090 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2091   _hrm.iterate(cl);
2092 }
2093 
2094 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2095                                                                  HeapRegionClaimer *hrclaimer,
2096                                                                  uint worker_id) const {
2097   _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2098 }
2099 
2100 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2101                                                          HeapRegionClaimer *hrclaimer) const {
2102   _hrm.par_iterate(cl, hrclaimer, 0);
2103 }
2104 
2105 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2106   _collection_set.iterate(cl);
2107 }
2108 
2109 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2110   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2111 }
2112 
2113 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2114   HeapRegion* hr = heap_region_containing(addr);
2115   return hr->block_start(addr);
2116 }
2117 
2118 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2119   HeapRegion* hr = heap_region_containing(addr);
2120   return hr->block_size(addr);
2121 }
2122 
2123 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2124   HeapRegion* hr = heap_region_containing(addr);
2125   return hr->block_is_obj(addr);
2126 }
2127 
2128 bool G1CollectedHeap::supports_tlab_allocation() const {
2129   return true;
2130 }
2131 
2132 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2133   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2134 }
2135 
2136 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2137   return _eden.length() * HeapRegion::GrainBytes;
2138 }
2139 
2140 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2141 // must be equal to the humongous object limit.
2142 size_t G1CollectedHeap::max_tlab_size() const {
2143   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2144 }
2145 
2146 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2147   return _allocator->unsafe_max_tlab_alloc();
2148 }
2149 
2150 size_t G1CollectedHeap::max_capacity() const {
2151   return _hrm.reserved().byte_size();
2152 }
2153 
2154 jlong G1CollectedHeap::millis_since_last_gc() {
2155   // See the notes in GenCollectedHeap::millis_since_last_gc()
2156   // for more information about the implementation.
2157   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2158     _g1_policy->collection_pause_end_millis();
2159   if (ret_val < 0) {
2160     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2161       ". returning zero instead.", ret_val);
2162     return 0;
2163   }
2164   return ret_val;
2165 }
2166 
2167 void G1CollectedHeap::prepare_for_verify() {
2168   _verifier->prepare_for_verify();
2169 }
2170 
2171 void G1CollectedHeap::verify(VerifyOption vo) {
2172   _verifier->verify(vo);
2173 }
2174 
2175 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2176   return true;
2177 }
2178 
2179 const char* const* G1CollectedHeap::concurrent_phases() const {
2180   return _cm_thread->concurrent_phases();
2181 }
2182 
2183 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2184   return _cm_thread->request_concurrent_phase(phase);
2185 }
2186 
2187 class PrintRegionClosure: public HeapRegionClosure {
2188   outputStream* _st;
2189 public:
2190   PrintRegionClosure(outputStream* st) : _st(st) {}
2191   bool do_heap_region(HeapRegion* r) {
2192     r->print_on(_st);
2193     return false;
2194   }
2195 };
2196 
2197 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2198                                        const HeapRegion* hr,
2199                                        const VerifyOption vo) const {
2200   switch (vo) {
2201   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2202   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2203   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2204   default:                            ShouldNotReachHere();
2205   }
2206   return false; // keep some compilers happy
2207 }
2208 
2209 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2210                                        const VerifyOption vo) const {
2211   switch (vo) {
2212   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2213   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2214   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2215   default:                            ShouldNotReachHere();
2216   }
2217   return false; // keep some compilers happy
2218 }
2219 
2220 void G1CollectedHeap::print_heap_regions() const {
2221   LogTarget(Trace, gc, heap, region) lt;
2222   if (lt.is_enabled()) {
2223     LogStream ls(lt);
2224     print_regions_on(&ls);
2225   }
2226 }
2227 
2228 void G1CollectedHeap::print_on(outputStream* st) const {
2229   st->print(" %-20s", "garbage-first heap");
2230   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2231             capacity()/K, used_unlocked()/K);
2232   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2233             p2i(_hrm.reserved().start()),
2234             p2i(_hrm.reserved().end()));
2235   st->cr();
2236   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2237   uint young_regions = young_regions_count();
2238   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2239             (size_t) young_regions * HeapRegion::GrainBytes / K);
2240   uint survivor_regions = survivor_regions_count();
2241   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2242             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2243   st->cr();
2244   MetaspaceUtils::print_on(st);
2245 }
2246 
2247 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2248   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2249                "HS=humongous(starts), HC=humongous(continues), "
2250                "CS=collection set, F=free, A=archive, "
2251                "TAMS=top-at-mark-start (previous, next)");
2252   PrintRegionClosure blk(st);
2253   heap_region_iterate(&blk);
2254 }
2255 
2256 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2257   print_on(st);
2258 
2259   // Print the per-region information.
2260   print_regions_on(st);
2261 }
2262 
2263 void G1CollectedHeap::print_on_error(outputStream* st) const {
2264   this->CollectedHeap::print_on_error(st);
2265 
2266   if (_cm != NULL) {
2267     st->cr();
2268     _cm->print_on_error(st);
2269   }
2270 }
2271 
2272 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2273   workers()->print_worker_threads_on(st);
2274   _cm_thread->print_on(st);
2275   st->cr();
2276   _cm->print_worker_threads_on(st);
2277   _cr->print_threads_on(st);
2278   _young_gen_sampling_thread->print_on(st);
2279   if (G1StringDedup::is_enabled()) {
2280     G1StringDedup::print_worker_threads_on(st);
2281   }
2282 }
2283 
2284 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2285   workers()->threads_do(tc);
2286   tc->do_thread(_cm_thread);
2287   _cm->threads_do(tc);
2288   _cr->threads_do(tc);
2289   tc->do_thread(_young_gen_sampling_thread);
2290   if (G1StringDedup::is_enabled()) {
2291     G1StringDedup::threads_do(tc);
2292   }
2293 }
2294 
2295 void G1CollectedHeap::print_tracing_info() const {
2296   g1_rem_set()->print_summary_info();
2297   concurrent_mark()->print_summary_info();
2298 }
2299 
2300 #ifndef PRODUCT
2301 // Helpful for debugging RSet issues.
2302 
2303 class PrintRSetsClosure : public HeapRegionClosure {
2304 private:
2305   const char* _msg;
2306   size_t _occupied_sum;
2307 
2308 public:
2309   bool do_heap_region(HeapRegion* r) {
2310     HeapRegionRemSet* hrrs = r->rem_set();
2311     size_t occupied = hrrs->occupied();
2312     _occupied_sum += occupied;
2313 
2314     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2315     if (occupied == 0) {
2316       tty->print_cr("  RSet is empty");
2317     } else {
2318       hrrs->print();
2319     }
2320     tty->print_cr("----------");
2321     return false;
2322   }
2323 
2324   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2325     tty->cr();
2326     tty->print_cr("========================================");
2327     tty->print_cr("%s", msg);
2328     tty->cr();
2329   }
2330 
2331   ~PrintRSetsClosure() {
2332     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2333     tty->print_cr("========================================");
2334     tty->cr();
2335   }
2336 };
2337 
2338 void G1CollectedHeap::print_cset_rsets() {
2339   PrintRSetsClosure cl("Printing CSet RSets");
2340   collection_set_iterate(&cl);
2341 }
2342 
2343 void G1CollectedHeap::print_all_rsets() {
2344   PrintRSetsClosure cl("Printing All RSets");;
2345   heap_region_iterate(&cl);
2346 }
2347 #endif // PRODUCT
2348 
2349 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2350 
2351   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2352   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2353   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2354 
2355   size_t eden_capacity_bytes =
2356     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2357 
2358   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2359   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2360                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2361 }
2362 
2363 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2364   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2365                        stats->unused(), stats->used(), stats->region_end_waste(),
2366                        stats->regions_filled(), stats->direct_allocated(),
2367                        stats->failure_used(), stats->failure_waste());
2368 }
2369 
2370 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2371   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2372   gc_tracer->report_gc_heap_summary(when, heap_summary);
2373 
2374   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2375   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2376 }
2377 
2378 G1CollectedHeap* G1CollectedHeap::heap() {
2379   CollectedHeap* heap = Universe::heap();
2380   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2381   assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2382   return (G1CollectedHeap*)heap;
2383 }
2384 
2385 void G1CollectedHeap::gc_prologue(bool full) {
2386   // always_do_update_barrier = false;
2387   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2388 
2389   // This summary needs to be printed before incrementing total collections.
2390   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2391 
2392   // Update common counters.
2393   increment_total_collections(full /* full gc */);
2394   if (full) {
2395     increment_old_marking_cycles_started();
2396   }
2397 
2398   // Fill TLAB's and such
2399   double start = os::elapsedTime();
2400   accumulate_statistics_all_tlabs();
2401   ensure_parsability(true);
2402   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2403 }
2404 
2405 void G1CollectedHeap::gc_epilogue(bool full) {
2406   // Update common counters.
2407   if (full) {
2408     // Update the number of full collections that have been completed.
2409     increment_old_marking_cycles_completed(false /* concurrent */);
2410   }
2411 
2412   // We are at the end of the GC. Total collections has already been increased.
2413   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2414 
2415   // FIXME: what is this about?
2416   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2417   // is set.
2418 #if COMPILER2_OR_JVMCI
2419   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2420 #endif
2421   // always_do_update_barrier = true;
2422 
2423   double start = os::elapsedTime();
2424   resize_all_tlabs();
2425   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2426 
2427   MemoryService::track_memory_usage();
2428   // We have just completed a GC. Update the soft reference
2429   // policy with the new heap occupancy
2430   Universe::update_heap_info_at_gc();
2431 }
2432 
2433 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2434                                                uint gc_count_before,
2435                                                bool* succeeded,
2436                                                GCCause::Cause gc_cause) {
2437   assert_heap_not_locked_and_not_at_safepoint();
2438   VM_G1CollectForAllocation op(word_size,
2439                                gc_count_before,
2440                                gc_cause,
2441                                false, /* should_initiate_conc_mark */
2442                                g1_policy()->max_pause_time_ms());
2443   VMThread::execute(&op);
2444 
2445   HeapWord* result = op.result();
2446   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2447   assert(result == NULL || ret_succeeded,
2448          "the result should be NULL if the VM did not succeed");
2449   *succeeded = ret_succeeded;
2450 
2451   assert_heap_not_locked();
2452   return result;
2453 }
2454 
2455 void G1CollectedHeap::do_concurrent_mark() {
2456   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2457   if (!_cm_thread->in_progress()) {
2458     _cm_thread->set_started();
2459     CGC_lock->notify();
2460   }
2461 }
2462 
2463 size_t G1CollectedHeap::pending_card_num() {
2464   size_t extra_cards = 0;
2465   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2466     DirtyCardQueue& dcq = curr->dirty_card_queue();
2467     extra_cards += dcq.size();
2468   }
2469   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2470   size_t buffer_size = dcqs.buffer_size();
2471   size_t buffer_num = dcqs.completed_buffers_num();
2472 
2473   return buffer_size * buffer_num + extra_cards;
2474 }
2475 
2476 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2477   // We don't nominate objects with many remembered set entries, on
2478   // the assumption that such objects are likely still live.
2479   HeapRegionRemSet* rem_set = r->rem_set();
2480 
2481   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2482          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2483          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2484 }
2485 
2486 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2487  private:
2488   size_t _total_humongous;
2489   size_t _candidate_humongous;
2490 
2491   DirtyCardQueue _dcq;
2492 
2493   bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2494     assert(region->is_starts_humongous(), "Must start a humongous object");
2495 
2496     oop obj = oop(region->bottom());
2497 
2498     // Dead objects cannot be eager reclaim candidates. Due to class
2499     // unloading it is unsafe to query their classes so we return early.
2500     if (g1h->is_obj_dead(obj, region)) {
2501       return false;
2502     }
2503 
2504     // If we do not have a complete remembered set for the region, then we can
2505     // not be sure that we have all references to it.
2506     if (!region->rem_set()->is_complete()) {
2507       return false;
2508     }
2509     // Candidate selection must satisfy the following constraints
2510     // while concurrent marking is in progress:
2511     //
2512     // * In order to maintain SATB invariants, an object must not be
2513     // reclaimed if it was allocated before the start of marking and
2514     // has not had its references scanned.  Such an object must have
2515     // its references (including type metadata) scanned to ensure no
2516     // live objects are missed by the marking process.  Objects
2517     // allocated after the start of concurrent marking don't need to
2518     // be scanned.
2519     //
2520     // * An object must not be reclaimed if it is on the concurrent
2521     // mark stack.  Objects allocated after the start of concurrent
2522     // marking are never pushed on the mark stack.
2523     //
2524     // Nominating only objects allocated after the start of concurrent
2525     // marking is sufficient to meet both constraints.  This may miss
2526     // some objects that satisfy the constraints, but the marking data
2527     // structures don't support efficiently performing the needed
2528     // additional tests or scrubbing of the mark stack.
2529     //
2530     // However, we presently only nominate is_typeArray() objects.
2531     // A humongous object containing references induces remembered
2532     // set entries on other regions.  In order to reclaim such an
2533     // object, those remembered sets would need to be cleaned up.
2534     //
2535     // We also treat is_typeArray() objects specially, allowing them
2536     // to be reclaimed even if allocated before the start of
2537     // concurrent mark.  For this we rely on mark stack insertion to
2538     // exclude is_typeArray() objects, preventing reclaiming an object
2539     // that is in the mark stack.  We also rely on the metadata for
2540     // such objects to be built-in and so ensured to be kept live.
2541     // Frequent allocation and drop of large binary blobs is an
2542     // important use case for eager reclaim, and this special handling
2543     // may reduce needed headroom.
2544 
2545     return obj->is_typeArray() &&
2546            g1h->is_potential_eager_reclaim_candidate(region);
2547   }
2548 
2549  public:
2550   RegisterHumongousWithInCSetFastTestClosure()
2551   : _total_humongous(0),
2552     _candidate_humongous(0),
2553     _dcq(&JavaThread::dirty_card_queue_set()) {
2554   }
2555 
2556   virtual bool do_heap_region(HeapRegion* r) {
2557     if (!r->is_starts_humongous()) {
2558       return false;
2559     }
2560     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2561 
2562     bool is_candidate = humongous_region_is_candidate(g1h, r);
2563     uint rindex = r->hrm_index();
2564     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2565     if (is_candidate) {
2566       _candidate_humongous++;
2567       g1h->register_humongous_region_with_cset(rindex);
2568       // Is_candidate already filters out humongous object with large remembered sets.
2569       // If we have a humongous object with a few remembered sets, we simply flush these
2570       // remembered set entries into the DCQS. That will result in automatic
2571       // re-evaluation of their remembered set entries during the following evacuation
2572       // phase.
2573       if (!r->rem_set()->is_empty()) {
2574         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2575                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2576         G1CardTable* ct = g1h->card_table();
2577         HeapRegionRemSetIterator hrrs(r->rem_set());
2578         size_t card_index;
2579         while (hrrs.has_next(card_index)) {
2580           jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2581           // The remembered set might contain references to already freed
2582           // regions. Filter out such entries to avoid failing card table
2583           // verification.
2584           if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2585             if (*card_ptr != G1CardTable::dirty_card_val()) {
2586               *card_ptr = G1CardTable::dirty_card_val();
2587               _dcq.enqueue(card_ptr);
2588             }
2589           }
2590         }
2591         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2592                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2593                hrrs.n_yielded(), r->rem_set()->occupied());
2594         // We should only clear the card based remembered set here as we will not
2595         // implicitly rebuild anything else during eager reclaim. Note that at the moment
2596         // (and probably never) we do not enter this path if there are other kind of
2597         // remembered sets for this region.
2598         r->rem_set()->clear_locked(true /* only_cardset */);
2599         // Clear_locked() above sets the state to Empty. However we want to continue
2600         // collecting remembered set entries for humongous regions that were not
2601         // reclaimed.
2602         r->rem_set()->set_state_complete();
2603       }
2604       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2605     }
2606     _total_humongous++;
2607 
2608     return false;
2609   }
2610 
2611   size_t total_humongous() const { return _total_humongous; }
2612   size_t candidate_humongous() const { return _candidate_humongous; }
2613 
2614   void flush_rem_set_entries() { _dcq.flush(); }
2615 };
2616 
2617 void G1CollectedHeap::register_humongous_regions_with_cset() {
2618   if (!G1EagerReclaimHumongousObjects) {
2619     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2620     return;
2621   }
2622   double time = os::elapsed_counter();
2623 
2624   // Collect reclaim candidate information and register candidates with cset.
2625   RegisterHumongousWithInCSetFastTestClosure cl;
2626   heap_region_iterate(&cl);
2627 
2628   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2629   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2630                                                                   cl.total_humongous(),
2631                                                                   cl.candidate_humongous());
2632   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2633 
2634   // Finally flush all remembered set entries to re-check into the global DCQS.
2635   cl.flush_rem_set_entries();
2636 }
2637 
2638 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2639   public:
2640     bool do_heap_region(HeapRegion* hr) {
2641       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2642         hr->verify_rem_set();
2643       }
2644       return false;
2645     }
2646 };
2647 
2648 uint G1CollectedHeap::num_task_queues() const {
2649   return _task_queues->size();
2650 }
2651 
2652 #if TASKQUEUE_STATS
2653 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2654   st->print_raw_cr("GC Task Stats");
2655   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2656   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2657 }
2658 
2659 void G1CollectedHeap::print_taskqueue_stats() const {
2660   if (!log_is_enabled(Trace, gc, task, stats)) {
2661     return;
2662   }
2663   Log(gc, task, stats) log;
2664   ResourceMark rm;
2665   LogStream ls(log.trace());
2666   outputStream* st = &ls;
2667 
2668   print_taskqueue_stats_hdr(st);
2669 
2670   TaskQueueStats totals;
2671   const uint n = num_task_queues();
2672   for (uint i = 0; i < n; ++i) {
2673     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2674     totals += task_queue(i)->stats;
2675   }
2676   st->print_raw("tot "); totals.print(st); st->cr();
2677 
2678   DEBUG_ONLY(totals.verify());
2679 }
2680 
2681 void G1CollectedHeap::reset_taskqueue_stats() {
2682   const uint n = num_task_queues();
2683   for (uint i = 0; i < n; ++i) {
2684     task_queue(i)->stats.reset();
2685   }
2686 }
2687 #endif // TASKQUEUE_STATS
2688 
2689 void G1CollectedHeap::wait_for_root_region_scanning() {
2690   double scan_wait_start = os::elapsedTime();
2691   // We have to wait until the CM threads finish scanning the
2692   // root regions as it's the only way to ensure that all the
2693   // objects on them have been correctly scanned before we start
2694   // moving them during the GC.
2695   bool waited = _cm->root_regions()->wait_until_scan_finished();
2696   double wait_time_ms = 0.0;
2697   if (waited) {
2698     double scan_wait_end = os::elapsedTime();
2699     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2700   }
2701   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2702 }
2703 
2704 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2705 private:
2706   G1HRPrinter* _hr_printer;
2707 public:
2708   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2709 
2710   virtual bool do_heap_region(HeapRegion* r) {
2711     _hr_printer->cset(r);
2712     return false;
2713   }
2714 };
2715 
2716 void G1CollectedHeap::start_new_collection_set() {
2717   collection_set()->start_incremental_building();
2718 
2719   clear_cset_fast_test();
2720 
2721   guarantee(_eden.length() == 0, "eden should have been cleared");
2722   g1_policy()->transfer_survivors_to_cset(survivor());
2723 }
2724 
2725 bool
2726 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2727   assert_at_safepoint_on_vm_thread();
2728   guarantee(!is_gc_active(), "collection is not reentrant");
2729 
2730   if (GCLocker::check_active_before_gc()) {
2731     return false;
2732   }
2733 
2734   _gc_timer_stw->register_gc_start();
2735 
2736   GCIdMark gc_id_mark;
2737   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2738 
2739   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2740   ResourceMark rm;
2741 
2742   g1_policy()->note_gc_start();
2743 
2744   wait_for_root_region_scanning();
2745 
2746   print_heap_before_gc();
2747   print_heap_regions();
2748   trace_heap_before_gc(_gc_tracer_stw);
2749 
2750   _verifier->verify_region_sets_optional();
2751   _verifier->verify_dirty_young_regions();
2752 
2753   // We should not be doing initial mark unless the conc mark thread is running
2754   if (!_cm_thread->should_terminate()) {
2755     // This call will decide whether this pause is an initial-mark
2756     // pause. If it is, in_initial_mark_gc() will return true
2757     // for the duration of this pause.
2758     g1_policy()->decide_on_conc_mark_initiation();
2759   }
2760 
2761   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2762   assert(!collector_state()->in_initial_mark_gc() ||
2763           collector_state()->in_young_only_phase(), "sanity");
2764 
2765   // We also do not allow mixed GCs during marking.
2766   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2767 
2768   // Record whether this pause is an initial mark. When the current
2769   // thread has completed its logging output and it's safe to signal
2770   // the CM thread, the flag's value in the policy has been reset.
2771   bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2772 
2773   // Inner scope for scope based logging, timers, and stats collection
2774   {
2775     EvacuationInfo evacuation_info;
2776 
2777     if (collector_state()->in_initial_mark_gc()) {
2778       // We are about to start a marking cycle, so we increment the
2779       // full collection counter.
2780       increment_old_marking_cycles_started();
2781       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2782     }
2783 
2784     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2785 
2786     GCTraceCPUTime tcpu;
2787 
2788     G1HeapVerifier::G1VerifyType verify_type;
2789     FormatBuffer<> gc_string("Pause ");
2790     if (collector_state()->in_initial_mark_gc()) {
2791       gc_string.append("Initial Mark");
2792       verify_type = G1HeapVerifier::G1VerifyInitialMark;
2793     } else if (collector_state()->in_young_only_phase()) {
2794       gc_string.append("Young");
2795       verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2796     } else {
2797       gc_string.append("Mixed");
2798       verify_type = G1HeapVerifier::G1VerifyMixed;
2799     }
2800     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2801 
2802     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2803                                                                   workers()->active_workers(),
2804                                                                   Threads::number_of_non_daemon_threads());
2805     active_workers = workers()->update_active_workers(active_workers);
2806     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2807 
2808     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2809     TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2810 
2811     G1HeapTransition heap_transition(this);
2812     size_t heap_used_bytes_before_gc = used();
2813 
2814     // Don't dynamically change the number of GC threads this early.  A value of
2815     // 0 is used to indicate serial work.  When parallel work is done,
2816     // it will be set.
2817 
2818     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2819       IsGCActiveMark x;
2820 
2821       gc_prologue(false);
2822 
2823       if (VerifyRememberedSets) {
2824         log_info(gc, verify)("[Verifying RemSets before GC]");
2825         VerifyRegionRemSetClosure v_cl;
2826         heap_region_iterate(&v_cl);
2827       }
2828 
2829       _verifier->verify_before_gc(verify_type);
2830 
2831       _verifier->check_bitmaps("GC Start");
2832 
2833 #if COMPILER2_OR_JVMCI
2834       DerivedPointerTable::clear();
2835 #endif
2836 
2837       // Please see comment in g1CollectedHeap.hpp and
2838       // G1CollectedHeap::ref_processing_init() to see how
2839       // reference processing currently works in G1.
2840 
2841       // Enable discovery in the STW reference processor
2842       ref_processor_stw()->enable_discovery();
2843 
2844       {
2845         // We want to temporarily turn off discovery by the
2846         // CM ref processor, if necessary, and turn it back on
2847         // on again later if we do. Using a scoped
2848         // NoRefDiscovery object will do this.
2849         NoRefDiscovery no_cm_discovery(ref_processor_cm());
2850 
2851         // Forget the current alloc region (we might even choose it to be part
2852         // of the collection set!).
2853         _allocator->release_mutator_alloc_region();
2854 
2855         // This timing is only used by the ergonomics to handle our pause target.
2856         // It is unclear why this should not include the full pause. We will
2857         // investigate this in CR 7178365.
2858         //
2859         // Preserving the old comment here if that helps the investigation:
2860         //
2861         // The elapsed time induced by the start time below deliberately elides
2862         // the possible verification above.
2863         double sample_start_time_sec = os::elapsedTime();
2864 
2865         g1_policy()->record_collection_pause_start(sample_start_time_sec);
2866 
2867         if (collector_state()->in_initial_mark_gc()) {
2868           concurrent_mark()->pre_initial_mark();
2869         }
2870 
2871         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2872 
2873         evacuation_info.set_collectionset_regions(collection_set()->region_length());
2874 
2875         // Make sure the remembered sets are up to date. This needs to be
2876         // done before register_humongous_regions_with_cset(), because the
2877         // remembered sets are used there to choose eager reclaim candidates.
2878         // If the remembered sets are not up to date we might miss some
2879         // entries that need to be handled.
2880         g1_rem_set()->cleanupHRRS();
2881 
2882         register_humongous_regions_with_cset();
2883 
2884         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2885 
2886         // We call this after finalize_cset() to
2887         // ensure that the CSet has been finalized.
2888         _cm->verify_no_cset_oops();
2889 
2890         if (_hr_printer.is_active()) {
2891           G1PrintCollectionSetClosure cl(&_hr_printer);
2892           _collection_set.iterate(&cl);
2893         }
2894 
2895         // Initialize the GC alloc regions.
2896         _allocator->init_gc_alloc_regions(evacuation_info);
2897 
2898         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2899         pre_evacuate_collection_set();
2900 
2901         // Actually do the work...
2902         evacuate_collection_set(&per_thread_states);
2903 
2904         post_evacuate_collection_set(evacuation_info, &per_thread_states);
2905 
2906         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
2907         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
2908 
2909         eagerly_reclaim_humongous_regions();
2910 
2911         record_obj_copy_mem_stats();
2912         _survivor_evac_stats.adjust_desired_plab_sz();
2913         _old_evac_stats.adjust_desired_plab_sz();
2914 
2915         double start = os::elapsedTime();
2916         start_new_collection_set();
2917         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2918 
2919         if (evacuation_failed()) {
2920           set_used(recalculate_used());
2921           if (_archive_allocator != NULL) {
2922             _archive_allocator->clear_used();
2923           }
2924           for (uint i = 0; i < ParallelGCThreads; i++) {
2925             if (_evacuation_failed_info_array[i].has_failed()) {
2926               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
2927             }
2928           }
2929         } else {
2930           // The "used" of the the collection set have already been subtracted
2931           // when they were freed.  Add in the bytes evacuated.
2932           increase_used(g1_policy()->bytes_copied_during_gc());
2933         }
2934 
2935         if (collector_state()->in_initial_mark_gc()) {
2936           // We have to do this before we notify the CM threads that
2937           // they can start working to make sure that all the
2938           // appropriate initialization is done on the CM object.
2939           concurrent_mark()->post_initial_mark();
2940           // Note that we don't actually trigger the CM thread at
2941           // this point. We do that later when we're sure that
2942           // the current thread has completed its logging output.
2943         }
2944 
2945         allocate_dummy_regions();
2946 
2947         _allocator->init_mutator_alloc_region();
2948 
2949         {
2950           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2951           if (expand_bytes > 0) {
2952             size_t bytes_before = capacity();
2953             // No need for an ergo logging here,
2954             // expansion_amount() does this when it returns a value > 0.
2955             double expand_ms;
2956             if (!expand(expand_bytes, _workers, &expand_ms)) {
2957               // We failed to expand the heap. Cannot do anything about it.
2958             }
2959             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
2960           }
2961         }
2962 
2963         // We redo the verification but now wrt to the new CSet which
2964         // has just got initialized after the previous CSet was freed.
2965         _cm->verify_no_cset_oops();
2966 
2967         // This timing is only used by the ergonomics to handle our pause target.
2968         // It is unclear why this should not include the full pause. We will
2969         // investigate this in CR 7178365.
2970         double sample_end_time_sec = os::elapsedTime();
2971         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
2972         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
2973         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
2974 
2975         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
2976         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
2977 
2978         if (VerifyRememberedSets) {
2979           log_info(gc, verify)("[Verifying RemSets after GC]");
2980           VerifyRegionRemSetClosure v_cl;
2981           heap_region_iterate(&v_cl);
2982         }
2983 
2984         _verifier->verify_after_gc(verify_type);
2985         _verifier->check_bitmaps("GC End");
2986 
2987         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
2988         ref_processor_stw()->verify_no_references_recorded();
2989 
2990         // CM reference discovery will be re-enabled if necessary.
2991       }
2992 
2993 #ifdef TRACESPINNING
2994       ParallelTaskTerminator::print_termination_counts();
2995 #endif
2996 
2997       gc_epilogue(false);
2998     }
2999 
3000     // Print the remainder of the GC log output.
3001     if (evacuation_failed()) {
3002       log_info(gc)("To-space exhausted");
3003     }
3004 
3005     g1_policy()->print_phases();
3006     heap_transition.print();
3007 
3008     // It is not yet to safe to tell the concurrent mark to
3009     // start as we have some optional output below. We don't want the
3010     // output from the concurrent mark thread interfering with this
3011     // logging output either.
3012 
3013     _hrm.verify_optional();
3014     _verifier->verify_region_sets_optional();
3015 
3016     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3017     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3018 
3019     print_heap_after_gc();
3020     print_heap_regions();
3021     trace_heap_after_gc(_gc_tracer_stw);
3022 
3023     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3024     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3025     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3026     // before any GC notifications are raised.
3027     g1mm()->update_sizes();
3028 
3029     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3030     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3031     _gc_timer_stw->register_gc_end();
3032     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3033   }
3034   // It should now be safe to tell the concurrent mark thread to start
3035   // without its logging output interfering with the logging output
3036   // that came from the pause.
3037 
3038   if (should_start_conc_mark) {
3039     // CAUTION: after the doConcurrentMark() call below,
3040     // the concurrent marking thread(s) could be running
3041     // concurrently with us. Make sure that anything after
3042     // this point does not assume that we are the only GC thread
3043     // running. Note: of course, the actual marking work will
3044     // not start until the safepoint itself is released in
3045     // SuspendibleThreadSet::desynchronize().
3046     do_concurrent_mark();
3047   }
3048 
3049   return true;
3050 }
3051 
3052 void G1CollectedHeap::remove_self_forwarding_pointers() {
3053   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3054   workers()->run_task(&rsfp_task);
3055 }
3056 
3057 void G1CollectedHeap::restore_after_evac_failure() {
3058   double remove_self_forwards_start = os::elapsedTime();
3059 
3060   remove_self_forwarding_pointers();
3061   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3062   _preserved_marks_set.restore(&task_executor);
3063 
3064   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3065 }
3066 
3067 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3068   if (!_evacuation_failed) {
3069     _evacuation_failed = true;
3070   }
3071 
3072   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3073   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3074 }
3075 
3076 bool G1ParEvacuateFollowersClosure::offer_termination() {
3077   G1ParScanThreadState* const pss = par_scan_state();
3078   start_term_time();
3079   const bool res = terminator()->offer_termination();
3080   end_term_time();
3081   return res;
3082 }
3083 
3084 void G1ParEvacuateFollowersClosure::do_void() {
3085   G1ParScanThreadState* const pss = par_scan_state();
3086   pss->trim_queue();
3087   do {
3088     pss->steal_and_trim_queue(queues());
3089   } while (!offer_termination());
3090 }
3091 
3092 class G1ParTask : public AbstractGangTask {
3093 protected:
3094   G1CollectedHeap*         _g1h;
3095   G1ParScanThreadStateSet* _pss;
3096   RefToScanQueueSet*       _queues;
3097   G1RootProcessor*         _root_processor;
3098   ParallelTaskTerminator   _terminator;
3099   uint                     _n_workers;
3100 
3101 public:
3102   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3103     : AbstractGangTask("G1 collection"),
3104       _g1h(g1h),
3105       _pss(per_thread_states),
3106       _queues(task_queues),
3107       _root_processor(root_processor),
3108       _terminator(n_workers, _queues),
3109       _n_workers(n_workers)
3110   {}
3111 
3112   void work(uint worker_id) {
3113     if (worker_id >= _n_workers) return;  // no work needed this round
3114 
3115     double start_sec = os::elapsedTime();
3116     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3117 
3118     {
3119       ResourceMark rm;
3120       HandleMark   hm;
3121 
3122       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3123 
3124       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3125       pss->set_ref_processor(rp);
3126 
3127       double start_strong_roots_sec = os::elapsedTime();
3128 
3129       _root_processor->evacuate_roots(pss, worker_id);
3130 
3131       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3132       // treating the nmethods visited to act as roots for concurrent marking.
3133       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3134       // objects copied by the current evacuation.
3135       _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3136 
3137       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3138 
3139       double term_sec = 0.0;
3140       size_t evac_term_attempts = 0;
3141       {
3142         double start = os::elapsedTime();
3143         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3144         evac.do_void();
3145 
3146         evac_term_attempts = evac.term_attempts();
3147         term_sec = evac.term_time();
3148         double elapsed_sec = os::elapsedTime() - start;
3149 
3150         G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3151         p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3152         p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3153         p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3154       }
3155 
3156       assert(pss->queue_is_empty(), "should be empty");
3157 
3158       if (log_is_enabled(Debug, gc, task, stats)) {
3159         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3160         size_t lab_waste;
3161         size_t lab_undo_waste;
3162         pss->waste(lab_waste, lab_undo_waste);
3163         _g1h->print_termination_stats(worker_id,
3164                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3165                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3166                                       term_sec * 1000.0,                          /* evac term time */
3167                                       evac_term_attempts,                         /* evac term attempts */
3168                                       lab_waste,                                  /* alloc buffer waste */
3169                                       lab_undo_waste                              /* undo waste */
3170                                       );
3171       }
3172 
3173       // Close the inner scope so that the ResourceMark and HandleMark
3174       // destructors are executed here and are included as part of the
3175       // "GC Worker Time".
3176     }
3177     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3178   }
3179 };
3180 
3181 void G1CollectedHeap::print_termination_stats_hdr() {
3182   log_debug(gc, task, stats)("GC Termination Stats");
3183   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3184   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3185   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3186 }
3187 
3188 void G1CollectedHeap::print_termination_stats(uint worker_id,
3189                                               double elapsed_ms,
3190                                               double strong_roots_ms,
3191                                               double term_ms,
3192                                               size_t term_attempts,
3193                                               size_t alloc_buffer_waste,
3194                                               size_t undo_waste) const {
3195   log_debug(gc, task, stats)
3196               ("%3d %9.2f %9.2f %6.2f "
3197                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3198                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3199                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3200                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3201                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3202                alloc_buffer_waste * HeapWordSize / K,
3203                undo_waste * HeapWordSize / K);
3204 }
3205 
3206 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3207 private:
3208   BoolObjectClosure* _is_alive;
3209   G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3210 
3211   int _initial_string_table_size;
3212   int _initial_symbol_table_size;
3213 
3214   bool  _process_strings;
3215   int _strings_processed;
3216   int _strings_removed;
3217 
3218   bool  _process_symbols;
3219   int _symbols_processed;
3220   int _symbols_removed;
3221 
3222   bool _process_string_dedup;
3223 
3224 public:
3225   G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3226     AbstractGangTask("String/Symbol Unlinking"),
3227     _is_alive(is_alive),
3228     _dedup_closure(is_alive, NULL, false),
3229     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3230     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3231     _process_string_dedup(process_string_dedup) {
3232 
3233     _initial_string_table_size = StringTable::the_table()->table_size();
3234     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3235     if (process_strings) {
3236       StringTable::clear_parallel_claimed_index();
3237     }
3238     if (process_symbols) {
3239       SymbolTable::clear_parallel_claimed_index();
3240     }
3241   }
3242 
3243   ~G1StringAndSymbolCleaningTask() {
3244     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3245               "claim value %d after unlink less than initial string table size %d",
3246               StringTable::parallel_claimed_index(), _initial_string_table_size);
3247     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3248               "claim value %d after unlink less than initial symbol table size %d",
3249               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3250 
3251     log_info(gc, stringtable)(
3252         "Cleaned string and symbol table, "
3253         "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3254         "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3255         strings_processed(), strings_removed(),
3256         symbols_processed(), symbols_removed());
3257   }
3258 
3259   void work(uint worker_id) {
3260     int strings_processed = 0;
3261     int strings_removed = 0;
3262     int symbols_processed = 0;
3263     int symbols_removed = 0;
3264     if (_process_strings) {
3265       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3266       Atomic::add(strings_processed, &_strings_processed);
3267       Atomic::add(strings_removed, &_strings_removed);
3268     }
3269     if (_process_symbols) {
3270       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3271       Atomic::add(symbols_processed, &_symbols_processed);
3272       Atomic::add(symbols_removed, &_symbols_removed);
3273     }
3274     if (_process_string_dedup) {
3275       G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3276     }
3277   }
3278 
3279   size_t strings_processed() const { return (size_t)_strings_processed; }
3280   size_t strings_removed()   const { return (size_t)_strings_removed; }
3281 
3282   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3283   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3284 };
3285 
3286 class G1CodeCacheUnloadingTask {
3287 private:
3288   static Monitor* _lock;
3289 
3290   BoolObjectClosure* const _is_alive;
3291   const bool               _unloading_occurred;
3292   const uint               _num_workers;
3293 
3294   // Variables used to claim nmethods.
3295   CompiledMethod* _first_nmethod;
3296   CompiledMethod* volatile _claimed_nmethod;
3297 
3298   // The list of nmethods that need to be processed by the second pass.
3299   CompiledMethod* volatile _postponed_list;
3300   volatile uint            _num_entered_barrier;
3301 
3302  public:
3303   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3304       _is_alive(is_alive),
3305       _unloading_occurred(unloading_occurred),
3306       _num_workers(num_workers),
3307       _first_nmethod(NULL),
3308       _claimed_nmethod(NULL),
3309       _postponed_list(NULL),
3310       _num_entered_barrier(0)
3311   {
3312     CompiledMethod::increase_unloading_clock();
3313     // Get first alive nmethod
3314     CompiledMethodIterator iter = CompiledMethodIterator();
3315     if(iter.next_alive()) {
3316       _first_nmethod = iter.method();
3317     }
3318     _claimed_nmethod = _first_nmethod;
3319   }
3320 
3321   ~G1CodeCacheUnloadingTask() {
3322     CodeCache::verify_clean_inline_caches();
3323 
3324     CodeCache::set_needs_cache_clean(false);
3325     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3326 
3327     CodeCache::verify_icholder_relocations();
3328   }
3329 
3330  private:
3331   void add_to_postponed_list(CompiledMethod* nm) {
3332       CompiledMethod* old;
3333       do {
3334         old = _postponed_list;
3335         nm->set_unloading_next(old);
3336       } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3337   }
3338 
3339   void clean_nmethod(CompiledMethod* nm) {
3340     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3341 
3342     if (postponed) {
3343       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3344       add_to_postponed_list(nm);
3345     }
3346 
3347     // Mark that this thread has been cleaned/unloaded.
3348     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3349     nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3350   }
3351 
3352   void clean_nmethod_postponed(CompiledMethod* nm) {
3353     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3354   }
3355 
3356   static const int MaxClaimNmethods = 16;
3357 
3358   void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3359     CompiledMethod* first;
3360     CompiledMethodIterator last;
3361 
3362     do {
3363       *num_claimed_nmethods = 0;
3364 
3365       first = _claimed_nmethod;
3366       last = CompiledMethodIterator(first);
3367 
3368       if (first != NULL) {
3369 
3370         for (int i = 0; i < MaxClaimNmethods; i++) {
3371           if (!last.next_alive()) {
3372             break;
3373           }
3374           claimed_nmethods[i] = last.method();
3375           (*num_claimed_nmethods)++;
3376         }
3377       }
3378 
3379     } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3380   }
3381 
3382   CompiledMethod* claim_postponed_nmethod() {
3383     CompiledMethod* claim;
3384     CompiledMethod* next;
3385 
3386     do {
3387       claim = _postponed_list;
3388       if (claim == NULL) {
3389         return NULL;
3390       }
3391 
3392       next = claim->unloading_next();
3393 
3394     } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3395 
3396     return claim;
3397   }
3398 
3399  public:
3400   // Mark that we're done with the first pass of nmethod cleaning.
3401   void barrier_mark(uint worker_id) {
3402     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3403     _num_entered_barrier++;
3404     if (_num_entered_barrier == _num_workers) {
3405       ml.notify_all();
3406     }
3407   }
3408 
3409   // See if we have to wait for the other workers to
3410   // finish their first-pass nmethod cleaning work.
3411   void barrier_wait(uint worker_id) {
3412     if (_num_entered_barrier < _num_workers) {
3413       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3414       while (_num_entered_barrier < _num_workers) {
3415           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3416       }
3417     }
3418   }
3419 
3420   // Cleaning and unloading of nmethods. Some work has to be postponed
3421   // to the second pass, when we know which nmethods survive.
3422   void work_first_pass(uint worker_id) {
3423     // The first nmethods is claimed by the first worker.
3424     if (worker_id == 0 && _first_nmethod != NULL) {
3425       clean_nmethod(_first_nmethod);
3426       _first_nmethod = NULL;
3427     }
3428 
3429     int num_claimed_nmethods;
3430     CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3431 
3432     while (true) {
3433       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3434 
3435       if (num_claimed_nmethods == 0) {
3436         break;
3437       }
3438 
3439       for (int i = 0; i < num_claimed_nmethods; i++) {
3440         clean_nmethod(claimed_nmethods[i]);
3441       }
3442     }
3443   }
3444 
3445   void work_second_pass(uint worker_id) {
3446     CompiledMethod* nm;
3447     // Take care of postponed nmethods.
3448     while ((nm = claim_postponed_nmethod()) != NULL) {
3449       clean_nmethod_postponed(nm);
3450     }
3451   }
3452 };
3453 
3454 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3455 
3456 class G1KlassCleaningTask : public StackObj {
3457   BoolObjectClosure*                      _is_alive;
3458   volatile int                            _clean_klass_tree_claimed;
3459   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3460 
3461  public:
3462   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3463       _is_alive(is_alive),
3464       _clean_klass_tree_claimed(0),
3465       _klass_iterator() {
3466   }
3467 
3468  private:
3469   bool claim_clean_klass_tree_task() {
3470     if (_clean_klass_tree_claimed) {
3471       return false;
3472     }
3473 
3474     return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3475   }
3476 
3477   InstanceKlass* claim_next_klass() {
3478     Klass* klass;
3479     do {
3480       klass =_klass_iterator.next_klass();
3481     } while (klass != NULL && !klass->is_instance_klass());
3482 
3483     // this can be null so don't call InstanceKlass::cast
3484     return static_cast<InstanceKlass*>(klass);
3485   }
3486 
3487 public:
3488 
3489   void clean_klass(InstanceKlass* ik) {
3490     ik->clean_weak_instanceklass_links(_is_alive);
3491   }
3492 
3493   void work() {
3494     ResourceMark rm;
3495 
3496     // One worker will clean the subklass/sibling klass tree.
3497     if (claim_clean_klass_tree_task()) {
3498       Klass::clean_subklass_tree(_is_alive);
3499     }
3500 
3501     // All workers will help cleaning the classes,
3502     InstanceKlass* klass;
3503     while ((klass = claim_next_klass()) != NULL) {
3504       clean_klass(klass);
3505     }
3506   }
3507 };
3508 
3509 class G1ResolvedMethodCleaningTask : public StackObj {
3510   BoolObjectClosure* _is_alive;
3511   volatile int       _resolved_method_task_claimed;
3512 public:
3513   G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3514       _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3515 
3516   bool claim_resolved_method_task() {
3517     if (_resolved_method_task_claimed) {
3518       return false;
3519     }
3520     return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3521   }
3522 
3523   // These aren't big, one thread can do it all.
3524   void work() {
3525     if (claim_resolved_method_task()) {
3526       ResolvedMethodTable::unlink(_is_alive);
3527     }
3528   }
3529 };
3530 
3531 
3532 // To minimize the remark pause times, the tasks below are done in parallel.
3533 class G1ParallelCleaningTask : public AbstractGangTask {
3534 private:
3535   G1StringAndSymbolCleaningTask _string_symbol_task;
3536   G1CodeCacheUnloadingTask      _code_cache_task;
3537   G1KlassCleaningTask           _klass_cleaning_task;
3538   G1ResolvedMethodCleaningTask  _resolved_method_cleaning_task;
3539 
3540 public:
3541   // The constructor is run in the VMThread.
3542   G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3543       AbstractGangTask("Parallel Cleaning"),
3544       _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3545       _code_cache_task(num_workers, is_alive, unloading_occurred),
3546       _klass_cleaning_task(is_alive),
3547       _resolved_method_cleaning_task(is_alive) {
3548   }
3549 
3550   // The parallel work done by all worker threads.
3551   void work(uint worker_id) {
3552     // Do first pass of code cache cleaning.
3553     _code_cache_task.work_first_pass(worker_id);
3554 
3555     // Let the threads mark that the first pass is done.
3556     _code_cache_task.barrier_mark(worker_id);
3557 
3558     // Clean the Strings and Symbols.
3559     _string_symbol_task.work(worker_id);
3560 
3561     // Clean unreferenced things in the ResolvedMethodTable
3562     _resolved_method_cleaning_task.work();
3563 
3564     // Wait for all workers to finish the first code cache cleaning pass.
3565     _code_cache_task.barrier_wait(worker_id);
3566 
3567     // Do the second code cache cleaning work, which realize on
3568     // the liveness information gathered during the first pass.
3569     _code_cache_task.work_second_pass(worker_id);
3570 
3571     // Clean all klasses that were not unloaded.
3572     _klass_cleaning_task.work();
3573   }
3574 };
3575 
3576 
3577 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3578                                         bool class_unloading_occurred) {
3579   uint n_workers = workers()->active_workers();
3580 
3581   G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3582   workers()->run_task(&g1_unlink_task);
3583 }
3584 
3585 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3586                                        bool process_strings,
3587                                        bool process_symbols,
3588                                        bool process_string_dedup) {
3589   if (!process_strings && !process_symbols && !process_string_dedup) {
3590     // Nothing to clean.
3591     return;
3592   }
3593 
3594   G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3595   workers()->run_task(&g1_unlink_task);
3596 
3597 }
3598 
3599 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3600  private:
3601   DirtyCardQueueSet* _queue;
3602   G1CollectedHeap* _g1h;
3603  public:
3604   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3605     _queue(queue), _g1h(g1h) { }
3606 
3607   virtual void work(uint worker_id) {
3608     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3609     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3610 
3611     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3612     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3613 
3614     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3615   }
3616 };
3617 
3618 void G1CollectedHeap::redirty_logged_cards() {
3619   double redirty_logged_cards_start = os::elapsedTime();
3620 
3621   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3622   dirty_card_queue_set().reset_for_par_iteration();
3623   workers()->run_task(&redirty_task);
3624 
3625   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3626   dcq.merge_bufferlists(&dirty_card_queue_set());
3627   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3628 
3629   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3630 }
3631 
3632 // Weak Reference Processing support
3633 
3634 // An always "is_alive" closure that is used to preserve referents.
3635 // If the object is non-null then it's alive.  Used in the preservation
3636 // of referent objects that are pointed to by reference objects
3637 // discovered by the CM ref processor.
3638 class G1AlwaysAliveClosure: public BoolObjectClosure {
3639 public:
3640   bool do_object_b(oop p) {
3641     if (p != NULL) {
3642       return true;
3643     }
3644     return false;
3645   }
3646 };
3647 
3648 bool G1STWIsAliveClosure::do_object_b(oop p) {
3649   // An object is reachable if it is outside the collection set,
3650   // or is inside and copied.
3651   return !_g1h->is_in_cset(p) || p->is_forwarded();
3652 }
3653 
3654 // Non Copying Keep Alive closure
3655 class G1KeepAliveClosure: public OopClosure {
3656   G1CollectedHeap*_g1h;
3657 public:
3658   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3659   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3660   void do_oop(oop* p) {
3661     oop obj = *p;
3662     assert(obj != NULL, "the caller should have filtered out NULL values");
3663 
3664     const InCSetState cset_state =_g1h->in_cset_state(obj);
3665     if (!cset_state.is_in_cset_or_humongous()) {
3666       return;
3667     }
3668     if (cset_state.is_in_cset()) {
3669       assert( obj->is_forwarded(), "invariant" );
3670       *p = obj->forwardee();
3671     } else {
3672       assert(!obj->is_forwarded(), "invariant" );
3673       assert(cset_state.is_humongous(),
3674              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3675      _g1h->set_humongous_is_live(obj);
3676     }
3677   }
3678 };
3679 
3680 // Copying Keep Alive closure - can be called from both
3681 // serial and parallel code as long as different worker
3682 // threads utilize different G1ParScanThreadState instances
3683 // and different queues.
3684 
3685 class G1CopyingKeepAliveClosure: public OopClosure {
3686   G1CollectedHeap*         _g1h;
3687   OopClosure*              _copy_non_heap_obj_cl;
3688   G1ParScanThreadState*    _par_scan_state;
3689 
3690 public:
3691   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3692                             OopClosure* non_heap_obj_cl,
3693                             G1ParScanThreadState* pss):
3694     _g1h(g1h),
3695     _copy_non_heap_obj_cl(non_heap_obj_cl),
3696     _par_scan_state(pss)
3697   {}
3698 
3699   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3700   virtual void do_oop(      oop* p) { do_oop_work(p); }
3701 
3702   template <class T> void do_oop_work(T* p) {
3703     oop obj = RawAccess<>::oop_load(p);
3704 
3705     if (_g1h->is_in_cset_or_humongous(obj)) {
3706       // If the referent object has been forwarded (either copied
3707       // to a new location or to itself in the event of an
3708       // evacuation failure) then we need to update the reference
3709       // field and, if both reference and referent are in the G1
3710       // heap, update the RSet for the referent.
3711       //
3712       // If the referent has not been forwarded then we have to keep
3713       // it alive by policy. Therefore we have copy the referent.
3714       //
3715       // If the reference field is in the G1 heap then we can push
3716       // on the PSS queue. When the queue is drained (after each
3717       // phase of reference processing) the object and it's followers
3718       // will be copied, the reference field set to point to the
3719       // new location, and the RSet updated. Otherwise we need to
3720       // use the the non-heap or metadata closures directly to copy
3721       // the referent object and update the pointer, while avoiding
3722       // updating the RSet.
3723 
3724       if (_g1h->is_in_g1_reserved(p)) {
3725         _par_scan_state->push_on_queue(p);
3726       } else {
3727         assert(!Metaspace::contains((const void*)p),
3728                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3729         _copy_non_heap_obj_cl->do_oop(p);
3730       }
3731     }
3732   }
3733 };
3734 
3735 // Serial drain queue closure. Called as the 'complete_gc'
3736 // closure for each discovered list in some of the
3737 // reference processing phases.
3738 
3739 class G1STWDrainQueueClosure: public VoidClosure {
3740 protected:
3741   G1CollectedHeap* _g1h;
3742   G1ParScanThreadState* _par_scan_state;
3743 
3744   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3745 
3746 public:
3747   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3748     _g1h(g1h),
3749     _par_scan_state(pss)
3750   { }
3751 
3752   void do_void() {
3753     G1ParScanThreadState* const pss = par_scan_state();
3754     pss->trim_queue();
3755   }
3756 };
3757 
3758 // Parallel Reference Processing closures
3759 
3760 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3761 // processing during G1 evacuation pauses.
3762 
3763 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3764 private:
3765   G1CollectedHeap*          _g1h;
3766   G1ParScanThreadStateSet*  _pss;
3767   RefToScanQueueSet*        _queues;
3768   WorkGang*                 _workers;
3769   uint                      _active_workers;
3770 
3771 public:
3772   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3773                            G1ParScanThreadStateSet* per_thread_states,
3774                            WorkGang* workers,
3775                            RefToScanQueueSet *task_queues,
3776                            uint n_workers) :
3777     _g1h(g1h),
3778     _pss(per_thread_states),
3779     _queues(task_queues),
3780     _workers(workers),
3781     _active_workers(n_workers)
3782   {
3783     g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3784   }
3785 
3786   // Executes the given task using concurrent marking worker threads.
3787   virtual void execute(ProcessTask& task);
3788   virtual void execute(EnqueueTask& task);
3789 };
3790 
3791 // Gang task for possibly parallel reference processing
3792 
3793 class G1STWRefProcTaskProxy: public AbstractGangTask {
3794   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3795   ProcessTask&     _proc_task;
3796   G1CollectedHeap* _g1h;
3797   G1ParScanThreadStateSet* _pss;
3798   RefToScanQueueSet* _task_queues;
3799   ParallelTaskTerminator* _terminator;
3800 
3801 public:
3802   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3803                         G1CollectedHeap* g1h,
3804                         G1ParScanThreadStateSet* per_thread_states,
3805                         RefToScanQueueSet *task_queues,
3806                         ParallelTaskTerminator* terminator) :
3807     AbstractGangTask("Process reference objects in parallel"),
3808     _proc_task(proc_task),
3809     _g1h(g1h),
3810     _pss(per_thread_states),
3811     _task_queues(task_queues),
3812     _terminator(terminator)
3813   {}
3814 
3815   virtual void work(uint worker_id) {
3816     // The reference processing task executed by a single worker.
3817     ResourceMark rm;
3818     HandleMark   hm;
3819 
3820     G1STWIsAliveClosure is_alive(_g1h);
3821 
3822     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
3823     pss->set_ref_processor(NULL);
3824 
3825     // Keep alive closure.
3826     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3827 
3828     // Complete GC closure
3829     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3830 
3831     // Call the reference processing task's work routine.
3832     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3833 
3834     // Note we cannot assert that the refs array is empty here as not all
3835     // of the processing tasks (specifically phase2 - pp2_work) execute
3836     // the complete_gc closure (which ordinarily would drain the queue) so
3837     // the queue may not be empty.
3838   }
3839 };
3840 
3841 // Driver routine for parallel reference processing.
3842 // Creates an instance of the ref processing gang
3843 // task and has the worker threads execute it.
3844 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3845   assert(_workers != NULL, "Need parallel worker threads.");
3846 
3847   ParallelTaskTerminator terminator(_active_workers, _queues);
3848   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3849 
3850   _workers->run_task(&proc_task_proxy);
3851 }
3852 
3853 // Gang task for parallel reference enqueueing.
3854 
3855 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
3856   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
3857   EnqueueTask& _enq_task;
3858 
3859 public:
3860   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
3861     AbstractGangTask("Enqueue reference objects in parallel"),
3862     _enq_task(enq_task)
3863   { }
3864 
3865   virtual void work(uint worker_id) {
3866     _enq_task.work(worker_id);
3867   }
3868 };
3869 
3870 // Driver routine for parallel reference enqueueing.
3871 // Creates an instance of the ref enqueueing gang
3872 // task and has the worker threads execute it.
3873 
3874 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
3875   assert(_workers != NULL, "Need parallel worker threads.");
3876 
3877   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
3878 
3879   _workers->run_task(&enq_task_proxy);
3880 }
3881 
3882 // End of weak reference support closures
3883 
3884 // Abstract task used to preserve (i.e. copy) any referent objects
3885 // that are in the collection set and are pointed to by reference
3886 // objects discovered by the CM ref processor.
3887 
3888 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
3889 protected:
3890   G1CollectedHeap*         _g1h;
3891   G1ParScanThreadStateSet* _pss;
3892   RefToScanQueueSet*       _queues;
3893   ParallelTaskTerminator   _terminator;
3894   uint                     _n_workers;
3895 
3896 public:
3897   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
3898     AbstractGangTask("ParPreserveCMReferents"),
3899     _g1h(g1h),
3900     _pss(per_thread_states),
3901     _queues(task_queues),
3902     _terminator(workers, _queues),
3903     _n_workers(workers)
3904   {
3905     g1h->ref_processor_cm()->set_active_mt_degree(workers);
3906   }
3907 
3908   void work(uint worker_id) {
3909     G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
3910 
3911     ResourceMark rm;
3912     HandleMark   hm;
3913 
3914     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
3915     pss->set_ref_processor(NULL);
3916     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3917 
3918     // Is alive closure
3919     G1AlwaysAliveClosure always_alive;
3920 
3921     // Copying keep alive closure. Applied to referent objects that need
3922     // to be copied.
3923     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3924 
3925     ReferenceProcessor* rp = _g1h->ref_processor_cm();
3926 
3927     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
3928     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
3929 
3930     // limit is set using max_num_q() - which was set using ParallelGCThreads.
3931     // So this must be true - but assert just in case someone decides to
3932     // change the worker ids.
3933     assert(worker_id < limit, "sanity");
3934     assert(!rp->discovery_is_atomic(), "check this code");
3935 
3936     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
3937     for (uint idx = worker_id; idx < limit; idx += stride) {
3938       DiscoveredList& ref_list = rp->discovered_refs()[idx];
3939 
3940       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
3941       while (iter.has_next()) {
3942         // Since discovery is not atomic for the CM ref processor, we
3943         // can see some null referent objects.
3944         iter.load_ptrs(DEBUG_ONLY(true));
3945         oop ref = iter.obj();
3946 
3947         // This will filter nulls.
3948         if (iter.is_referent_alive()) {
3949           iter.make_referent_alive();
3950         }
3951         iter.move_to_next();
3952       }
3953     }
3954 
3955     // Drain the queue - which may cause stealing
3956     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
3957     drain_queue.do_void();
3958     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
3959     assert(pss->queue_is_empty(), "should be");
3960   }
3961 };
3962 
3963 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
3964   // Any reference objects, in the collection set, that were 'discovered'
3965   // by the CM ref processor should have already been copied (either by
3966   // applying the external root copy closure to the discovered lists, or
3967   // by following an RSet entry).
3968   //
3969   // But some of the referents, that are in the collection set, that these
3970   // reference objects point to may not have been copied: the STW ref
3971   // processor would have seen that the reference object had already
3972   // been 'discovered' and would have skipped discovering the reference,
3973   // but would not have treated the reference object as a regular oop.
3974   // As a result the copy closure would not have been applied to the
3975   // referent object.
3976   //
3977   // We need to explicitly copy these referent objects - the references
3978   // will be processed at the end of remarking.
3979   //
3980   // We also need to do this copying before we process the reference
3981   // objects discovered by the STW ref processor in case one of these
3982   // referents points to another object which is also referenced by an
3983   // object discovered by the STW ref processor.
3984   double preserve_cm_referents_time = 0.0;
3985 
3986   // To avoid spawning task when there is no work to do, check that
3987   // a concurrent cycle is active and that some references have been
3988   // discovered.
3989   if (concurrent_mark()->cm_thread()->during_cycle() &&
3990       ref_processor_cm()->has_discovered_references()) {
3991     double preserve_cm_referents_start = os::elapsedTime();
3992     uint no_of_gc_workers = workers()->active_workers();
3993     G1ParPreserveCMReferentsTask keep_cm_referents(this,
3994                                                    per_thread_states,
3995                                                    no_of_gc_workers,
3996                                                    _task_queues);
3997     workers()->run_task(&keep_cm_referents);
3998     preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
3999   }
4000 
4001   g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4002 }
4003 
4004 // Weak Reference processing during an evacuation pause (part 1).
4005 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4006   double ref_proc_start = os::elapsedTime();
4007 
4008   ReferenceProcessor* rp = _ref_processor_stw;
4009   assert(rp->discovery_enabled(), "should have been enabled");
4010 
4011   // Closure to test whether a referent is alive.
4012   G1STWIsAliveClosure is_alive(this);
4013 
4014   // Even when parallel reference processing is enabled, the processing
4015   // of JNI refs is serial and performed serially by the current thread
4016   // rather than by a worker. The following PSS will be used for processing
4017   // JNI refs.
4018 
4019   // Use only a single queue for this PSS.
4020   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4021   pss->set_ref_processor(NULL);
4022   assert(pss->queue_is_empty(), "pre-condition");
4023 
4024   // Keep alive closure.
4025   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4026 
4027   // Serial Complete GC closure
4028   G1STWDrainQueueClosure drain_queue(this, pss);
4029 
4030   // Setup the soft refs policy...
4031   rp->setup_policy(false);
4032 
4033   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4034 
4035   ReferenceProcessorStats stats;
4036   if (!rp->processing_is_mt()) {
4037     // Serial reference processing...
4038     stats = rp->process_discovered_references(&is_alive,
4039                                               &keep_alive,
4040                                               &drain_queue,
4041                                               NULL,
4042                                               pt);
4043   } else {
4044     uint no_of_gc_workers = workers()->active_workers();
4045 
4046     // Parallel reference processing
4047     assert(no_of_gc_workers <= rp->max_num_q(),
4048            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4049            no_of_gc_workers,  rp->max_num_q());
4050 
4051     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4052     stats = rp->process_discovered_references(&is_alive,
4053                                               &keep_alive,
4054                                               &drain_queue,
4055                                               &par_task_executor,
4056                                               pt);
4057   }
4058 
4059   _gc_tracer_stw->report_gc_reference_stats(stats);
4060 
4061   // We have completed copying any necessary live referent objects.
4062   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4063 
4064   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4065   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4066 }
4067 
4068 // Weak Reference processing during an evacuation pause (part 2).
4069 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4070   double ref_enq_start = os::elapsedTime();
4071 
4072   ReferenceProcessor* rp = _ref_processor_stw;
4073   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4074 
4075   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4076 
4077   // Now enqueue any remaining on the discovered lists on to
4078   // the pending list.
4079   if (!rp->processing_is_mt()) {
4080     // Serial reference processing...
4081     rp->enqueue_discovered_references(NULL, pt);
4082   } else {
4083     // Parallel reference enqueueing
4084 
4085     uint n_workers = workers()->active_workers();
4086 
4087     assert(n_workers <= rp->max_num_q(),
4088            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4089            n_workers,  rp->max_num_q());
4090 
4091     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4092     rp->enqueue_discovered_references(&par_task_executor, pt);
4093   }
4094 
4095   rp->verify_no_references_recorded();
4096   assert(!rp->discovery_enabled(), "should have been disabled");
4097 
4098   // If during an initial mark pause we install a pending list head which is not otherwise reachable
4099   // ensure that it is marked in the bitmap for concurrent marking to discover.
4100   if (collector_state()->in_initial_mark_gc()) {
4101     oop pll_head = Universe::reference_pending_list();
4102     if (pll_head != NULL) {
4103       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
4104       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
4105     }
4106   }
4107 
4108   // FIXME
4109   // CM's reference processing also cleans up the string and symbol tables.
4110   // Should we do that here also? We could, but it is a serial operation
4111   // and could significantly increase the pause time.
4112 
4113   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4114   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4115 }
4116 
4117 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4118   double merge_pss_time_start = os::elapsedTime();
4119   per_thread_states->flush();
4120   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4121 }
4122 
4123 void G1CollectedHeap::pre_evacuate_collection_set() {
4124   _expand_heap_after_alloc_failure = true;
4125   _evacuation_failed = false;
4126 
4127   // Disable the hot card cache.
4128   _hot_card_cache->reset_hot_cache_claimed_index();
4129   _hot_card_cache->set_use_cache(false);
4130 
4131   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4132   _preserved_marks_set.assert_empty();
4133 
4134   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4135 
4136   // InitialMark needs claim bits to keep track of the marked-through CLDs.
4137   if (collector_state()->in_initial_mark_gc()) {
4138     double start_clear_claimed_marks = os::elapsedTime();
4139 
4140     ClassLoaderDataGraph::clear_claimed_marks();
4141 
4142     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4143     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4144   }
4145 }
4146 
4147 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
4148   // Should G1EvacuationFailureALot be in effect for this GC?
4149   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4150 
4151   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4152 
4153   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4154 
4155   double start_par_time_sec = os::elapsedTime();
4156   double end_par_time_sec;
4157 
4158   {
4159     const uint n_workers = workers()->active_workers();
4160     G1RootProcessor root_processor(this, n_workers);
4161     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4162 
4163     print_termination_stats_hdr();
4164 
4165     workers()->run_task(&g1_par_task);
4166     end_par_time_sec = os::elapsedTime();
4167 
4168     // Closing the inner scope will execute the destructor
4169     // for the G1RootProcessor object. We record the current
4170     // elapsed time before closing the scope so that time
4171     // taken for the destructor is NOT included in the
4172     // reported parallel time.
4173   }
4174 
4175   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4176   phase_times->record_par_time(par_time_ms);
4177 
4178   double code_root_fixup_time_ms =
4179         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4180   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4181 }
4182 
4183 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4184   // Process any discovered reference objects - we have
4185   // to do this _before_ we retire the GC alloc regions
4186   // as we may have to copy some 'reachable' referent
4187   // objects (and their reachable sub-graphs) that were
4188   // not copied during the pause.
4189   preserve_cm_referents(per_thread_states);
4190   process_discovered_references(per_thread_states);
4191 
4192   G1STWIsAliveClosure is_alive(this);
4193   G1KeepAliveClosure keep_alive(this);
4194 
4195   {
4196     double start = os::elapsedTime();
4197 
4198     WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4199 
4200     double time_ms = (os::elapsedTime() - start) * 1000.0;
4201     g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4202   }
4203 
4204   if (G1StringDedup::is_enabled()) {
4205     double fixup_start = os::elapsedTime();
4206 
4207     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4208 
4209     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4210     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4211   }
4212 
4213   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4214 
4215   if (evacuation_failed()) {
4216     restore_after_evac_failure();
4217 
4218     // Reset the G1EvacuationFailureALot counters and flags
4219     // Note: the values are reset only when an actual
4220     // evacuation failure occurs.
4221     NOT_PRODUCT(reset_evacuation_should_fail();)
4222   }
4223 
4224   _preserved_marks_set.assert_empty();
4225 
4226   // Enqueue any remaining references remaining on the STW
4227   // reference processor's discovered lists. We need to do
4228   // this after the card table is cleaned (and verified) as
4229   // the act of enqueueing entries on to the pending list
4230   // will log these updates (and dirty their associated
4231   // cards). We need these updates logged to update any
4232   // RSets.
4233   enqueue_discovered_references(per_thread_states);
4234 
4235   _allocator->release_gc_alloc_regions(evacuation_info);
4236 
4237   merge_per_thread_state_info(per_thread_states);
4238 
4239   // Reset and re-enable the hot card cache.
4240   // Note the counts for the cards in the regions in the
4241   // collection set are reset when the collection set is freed.
4242   _hot_card_cache->reset_hot_cache();
4243   _hot_card_cache->set_use_cache(true);
4244 
4245   purge_code_root_memory();
4246 
4247   redirty_logged_cards();
4248 #if COMPILER2_OR_JVMCI
4249   double start = os::elapsedTime();
4250   DerivedPointerTable::update_pointers();
4251   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4252 #endif
4253   g1_policy()->print_age_table();
4254 }
4255 
4256 void G1CollectedHeap::record_obj_copy_mem_stats() {
4257   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4258 
4259   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4260                                                create_g1_evac_summary(&_old_evac_stats));
4261 }
4262 
4263 void G1CollectedHeap::free_region(HeapRegion* hr,
4264                                   FreeRegionList* free_list,
4265                                   bool skip_remset,
4266                                   bool skip_hot_card_cache,
4267                                   bool locked) {
4268   assert(!hr->is_free(), "the region should not be free");
4269   assert(!hr->is_empty(), "the region should not be empty");
4270   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4271   assert(free_list != NULL, "pre-condition");
4272 
4273   if (G1VerifyBitmaps) {
4274     MemRegion mr(hr->bottom(), hr->end());
4275     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4276   }
4277 
4278   // Clear the card counts for this region.
4279   // Note: we only need to do this if the region is not young
4280   // (since we don't refine cards in young regions).
4281   if (!skip_hot_card_cache && !hr->is_young()) {
4282     _hot_card_cache->reset_card_counts(hr);
4283   }
4284   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4285   _g1_policy->remset_tracker()->update_at_free(hr);
4286   free_list->add_ordered(hr);
4287 }
4288 
4289 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4290                                             FreeRegionList* free_list) {
4291   assert(hr->is_humongous(), "this is only for humongous regions");
4292   assert(free_list != NULL, "pre-condition");
4293   hr->clear_humongous();
4294   free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4295 }
4296 
4297 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4298                                            const uint humongous_regions_removed) {
4299   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4300     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4301     _old_set.bulk_remove(old_regions_removed);
4302     _humongous_set.bulk_remove(humongous_regions_removed);
4303   }
4304 
4305 }
4306 
4307 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4308   assert(list != NULL, "list can't be null");
4309   if (!list->is_empty()) {
4310     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4311     _hrm.insert_list_into_free_list(list);
4312   }
4313 }
4314 
4315 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4316   decrease_used(bytes);
4317 }
4318 
4319 class G1FreeCollectionSetTask : public AbstractGangTask {
4320 private:
4321 
4322   // Closure applied to all regions in the collection set to do work that needs to
4323   // be done serially in a single thread.
4324   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4325   private:
4326     EvacuationInfo* _evacuation_info;
4327     const size_t* _surviving_young_words;
4328 
4329     // Bytes used in successfully evacuated regions before the evacuation.
4330     size_t _before_used_bytes;
4331     // Bytes used in unsucessfully evacuated regions before the evacuation
4332     size_t _after_used_bytes;
4333 
4334     size_t _bytes_allocated_in_old_since_last_gc;
4335 
4336     size_t _failure_used_words;
4337     size_t _failure_waste_words;
4338 
4339     FreeRegionList _local_free_list;
4340   public:
4341     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4342       HeapRegionClosure(),
4343       _evacuation_info(evacuation_info),
4344       _surviving_young_words(surviving_young_words),
4345       _before_used_bytes(0),
4346       _after_used_bytes(0),
4347       _bytes_allocated_in_old_since_last_gc(0),
4348       _failure_used_words(0),
4349       _failure_waste_words(0),
4350       _local_free_list("Local Region List for CSet Freeing") {
4351     }
4352 
4353     virtual bool do_heap_region(HeapRegion* r) {
4354       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4355 
4356       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4357       g1h->clear_in_cset(r);
4358 
4359       if (r->is_young()) {
4360         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4361                "Young index %d is wrong for region %u of type %s with %u young regions",
4362                r->young_index_in_cset(),
4363                r->hrm_index(),
4364                r->get_type_str(),
4365                g1h->collection_set()->young_region_length());
4366         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4367         r->record_surv_words_in_group(words_survived);
4368       }
4369 
4370       if (!r->evacuation_failed()) {
4371         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4372         _before_used_bytes += r->used();
4373         g1h->free_region(r,
4374                          &_local_free_list,
4375                          true, /* skip_remset */
4376                          true, /* skip_hot_card_cache */
4377                          true  /* locked */);
4378       } else {
4379         r->uninstall_surv_rate_group();
4380         r->set_young_index_in_cset(-1);
4381         r->set_evacuation_failed(false);
4382         // When moving a young gen region to old gen, we "allocate" that whole region
4383         // there. This is in addition to any already evacuated objects. Notify the
4384         // policy about that.
4385         // Old gen regions do not cause an additional allocation: both the objects
4386         // still in the region and the ones already moved are accounted for elsewhere.
4387         if (r->is_young()) {
4388           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4389         }
4390         // The region is now considered to be old.
4391         r->set_old();
4392         // Do some allocation statistics accounting. Regions that failed evacuation
4393         // are always made old, so there is no need to update anything in the young
4394         // gen statistics, but we need to update old gen statistics.
4395         size_t used_words = r->marked_bytes() / HeapWordSize;
4396 
4397         _failure_used_words += used_words;
4398         _failure_waste_words += HeapRegion::GrainWords - used_words;
4399 
4400         g1h->old_set_add(r);
4401         _after_used_bytes += r->used();
4402       }
4403       return false;
4404     }
4405 
4406     void complete_work() {
4407       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4408 
4409       _evacuation_info->set_regions_freed(_local_free_list.length());
4410       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4411 
4412       g1h->prepend_to_freelist(&_local_free_list);
4413       g1h->decrement_summary_bytes(_before_used_bytes);
4414 
4415       G1Policy* policy = g1h->g1_policy();
4416       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4417 
4418       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4419     }
4420   };
4421 
4422   G1CollectionSet* _collection_set;
4423   G1SerialFreeCollectionSetClosure _cl;
4424   const size_t* _surviving_young_words;
4425 
4426   size_t _rs_lengths;
4427 
4428   volatile jint _serial_work_claim;
4429 
4430   struct WorkItem {
4431     uint region_idx;
4432     bool is_young;
4433     bool evacuation_failed;
4434 
4435     WorkItem(HeapRegion* r) {
4436       region_idx = r->hrm_index();
4437       is_young = r->is_young();
4438       evacuation_failed = r->evacuation_failed();
4439     }
4440   };
4441 
4442   volatile size_t _parallel_work_claim;
4443   size_t _num_work_items;
4444   WorkItem* _work_items;
4445 
4446   void do_serial_work() {
4447     // Need to grab the lock to be allowed to modify the old region list.
4448     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4449     _collection_set->iterate(&_cl);
4450   }
4451 
4452   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4453     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4454 
4455     HeapRegion* r = g1h->region_at(region_idx);
4456     assert(!g1h->is_on_master_free_list(r), "sanity");
4457 
4458     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4459 
4460     if (!is_young) {
4461       g1h->_hot_card_cache->reset_card_counts(r);
4462     }
4463 
4464     if (!evacuation_failed) {
4465       r->rem_set()->clear_locked();
4466     }
4467   }
4468 
4469   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4470   private:
4471     size_t _cur_idx;
4472     WorkItem* _work_items;
4473   public:
4474     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4475 
4476     virtual bool do_heap_region(HeapRegion* r) {
4477       _work_items[_cur_idx++] = WorkItem(r);
4478       return false;
4479     }
4480   };
4481 
4482   void prepare_work() {
4483     G1PrepareFreeCollectionSetClosure cl(_work_items);
4484     _collection_set->iterate(&cl);
4485   }
4486 
4487   void complete_work() {
4488     _cl.complete_work();
4489 
4490     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4491     policy->record_max_rs_lengths(_rs_lengths);
4492     policy->cset_regions_freed();
4493   }
4494 public:
4495   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4496     AbstractGangTask("G1 Free Collection Set"),
4497     _cl(evacuation_info, surviving_young_words),
4498     _collection_set(collection_set),
4499     _surviving_young_words(surviving_young_words),
4500     _serial_work_claim(0),
4501     _rs_lengths(0),
4502     _parallel_work_claim(0),
4503     _num_work_items(collection_set->region_length()),
4504     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4505     prepare_work();
4506   }
4507 
4508   ~G1FreeCollectionSetTask() {
4509     complete_work();
4510     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4511   }
4512 
4513   // Chunk size for work distribution. The chosen value has been determined experimentally
4514   // to be a good tradeoff between overhead and achievable parallelism.
4515   static uint chunk_size() { return 32; }
4516 
4517   virtual void work(uint worker_id) {
4518     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4519 
4520     // Claim serial work.
4521     if (_serial_work_claim == 0) {
4522       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4523       if (value == 0) {
4524         double serial_time = os::elapsedTime();
4525         do_serial_work();
4526         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4527       }
4528     }
4529 
4530     // Start parallel work.
4531     double young_time = 0.0;
4532     bool has_young_time = false;
4533     double non_young_time = 0.0;
4534     bool has_non_young_time = false;
4535 
4536     while (true) {
4537       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4538       size_t cur = end - chunk_size();
4539 
4540       if (cur >= _num_work_items) {
4541         break;
4542       }
4543 
4544       double start_time = os::elapsedTime();
4545 
4546       end = MIN2(end, _num_work_items);
4547 
4548       for (; cur < end; cur++) {
4549         bool is_young = _work_items[cur].is_young;
4550 
4551         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4552 
4553         double end_time = os::elapsedTime();
4554         double time_taken = end_time - start_time;
4555         if (is_young) {
4556           young_time += time_taken;
4557           has_young_time = true;
4558         } else {
4559           non_young_time += time_taken;
4560           has_non_young_time = true;
4561         }
4562         start_time = end_time;
4563       }
4564     }
4565 
4566     if (has_young_time) {
4567       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4568     }
4569     if (has_non_young_time) {
4570       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4571     }
4572   }
4573 };
4574 
4575 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4576   _eden.clear();
4577 
4578   double free_cset_start_time = os::elapsedTime();
4579 
4580   {
4581     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4582     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4583 
4584     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4585 
4586     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4587                         cl.name(),
4588                         num_workers,
4589                         _collection_set.region_length());
4590     workers()->run_task(&cl, num_workers);
4591   }
4592   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4593 
4594   collection_set->clear();
4595 }
4596 
4597 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4598  private:
4599   FreeRegionList* _free_region_list;
4600   HeapRegionSet* _proxy_set;
4601   uint _humongous_objects_reclaimed;
4602   uint _humongous_regions_reclaimed;
4603   size_t _freed_bytes;
4604  public:
4605 
4606   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4607     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4608   }
4609 
4610   virtual bool do_heap_region(HeapRegion* r) {
4611     if (!r->is_starts_humongous()) {
4612       return false;
4613     }
4614 
4615     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4616 
4617     oop obj = (oop)r->bottom();
4618     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4619 
4620     // The following checks whether the humongous object is live are sufficient.
4621     // The main additional check (in addition to having a reference from the roots
4622     // or the young gen) is whether the humongous object has a remembered set entry.
4623     //
4624     // A humongous object cannot be live if there is no remembered set for it
4625     // because:
4626     // - there can be no references from within humongous starts regions referencing
4627     // the object because we never allocate other objects into them.
4628     // (I.e. there are no intra-region references that may be missed by the
4629     // remembered set)
4630     // - as soon there is a remembered set entry to the humongous starts region
4631     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4632     // until the end of a concurrent mark.
4633     //
4634     // It is not required to check whether the object has been found dead by marking
4635     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4636     // all objects allocated during that time are considered live.
4637     // SATB marking is even more conservative than the remembered set.
4638     // So if at this point in the collection there is no remembered set entry,
4639     // nobody has a reference to it.
4640     // At the start of collection we flush all refinement logs, and remembered sets
4641     // are completely up-to-date wrt to references to the humongous object.
4642     //
4643     // Other implementation considerations:
4644     // - never consider object arrays at this time because they would pose
4645     // considerable effort for cleaning up the the remembered sets. This is
4646     // required because stale remembered sets might reference locations that
4647     // are currently allocated into.
4648     uint region_idx = r->hrm_index();
4649     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4650         !r->rem_set()->is_empty()) {
4651       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",
4652                                region_idx,
4653                                (size_t)obj->size() * HeapWordSize,
4654                                p2i(r->bottom()),
4655                                r->rem_set()->occupied(),
4656                                r->rem_set()->strong_code_roots_list_length(),
4657                                next_bitmap->is_marked(r->bottom()),
4658                                g1h->is_humongous_reclaim_candidate(region_idx),
4659                                obj->is_typeArray()
4660                               );
4661       return false;
4662     }
4663 
4664     guarantee(obj->is_typeArray(),
4665               "Only eagerly reclaiming type arrays is supported, but the object "
4666               PTR_FORMAT " is not.", p2i(r->bottom()));
4667 
4668     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",
4669                              region_idx,
4670                              (size_t)obj->size() * HeapWordSize,
4671                              p2i(r->bottom()),
4672                              r->rem_set()->occupied(),
4673                              r->rem_set()->strong_code_roots_list_length(),
4674                              next_bitmap->is_marked(r->bottom()),
4675                              g1h->is_humongous_reclaim_candidate(region_idx),
4676                              obj->is_typeArray()
4677                             );
4678 
4679     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4680     cm->humongous_object_eagerly_reclaimed(r);
4681     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4682            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4683            region_idx,
4684            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4685            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4686     _humongous_objects_reclaimed++;
4687     do {
4688       HeapRegion* next = g1h->next_region_in_humongous(r);
4689       _freed_bytes += r->used();
4690       r->set_containing_set(NULL);
4691       _humongous_regions_reclaimed++;
4692       g1h->free_humongous_region(r, _free_region_list);
4693       r = next;
4694     } while (r != NULL);
4695 
4696     return false;
4697   }
4698 
4699   uint humongous_objects_reclaimed() {
4700     return _humongous_objects_reclaimed;
4701   }
4702 
4703   uint humongous_regions_reclaimed() {
4704     return _humongous_regions_reclaimed;
4705   }
4706 
4707   size_t bytes_freed() const {
4708     return _freed_bytes;
4709   }
4710 };
4711 
4712 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4713   assert_at_safepoint_on_vm_thread();
4714 
4715   if (!G1EagerReclaimHumongousObjects ||
4716       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4717     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4718     return;
4719   }
4720 
4721   double start_time = os::elapsedTime();
4722 
4723   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4724 
4725   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4726   heap_region_iterate(&cl);
4727 
4728   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4729 
4730   G1HRPrinter* hrp = hr_printer();
4731   if (hrp->is_active()) {
4732     FreeRegionListIterator iter(&local_cleanup_list);
4733     while (iter.more_available()) {
4734       HeapRegion* hr = iter.get_next();
4735       hrp->cleanup(hr);
4736     }
4737   }
4738 
4739   prepend_to_freelist(&local_cleanup_list);
4740   decrement_summary_bytes(cl.bytes_freed());
4741 
4742   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4743                                                                     cl.humongous_objects_reclaimed());
4744 }
4745 
4746 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4747 public:
4748   virtual bool do_heap_region(HeapRegion* r) {
4749     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4750     G1CollectedHeap::heap()->clear_in_cset(r);
4751     r->set_young_index_in_cset(-1);
4752     return false;
4753   }
4754 };
4755 
4756 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4757   G1AbandonCollectionSetClosure cl;
4758   collection_set->iterate(&cl);
4759 
4760   collection_set->clear();
4761   collection_set->stop_incremental_building();
4762 }
4763 
4764 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4765   return _allocator->is_retained_old_region(hr);
4766 }
4767 
4768 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4769   _eden.add(hr);
4770   _g1_policy->set_region_eden(hr);
4771 }
4772 
4773 #ifdef ASSERT
4774 
4775 class NoYoungRegionsClosure: public HeapRegionClosure {
4776 private:
4777   bool _success;
4778 public:
4779   NoYoungRegionsClosure() : _success(true) { }
4780   bool do_heap_region(HeapRegion* r) {
4781     if (r->is_young()) {
4782       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4783                             p2i(r->bottom()), p2i(r->end()));
4784       _success = false;
4785     }
4786     return false;
4787   }
4788   bool success() { return _success; }
4789 };
4790 
4791 bool G1CollectedHeap::check_young_list_empty() {
4792   bool ret = (young_regions_count() == 0);
4793 
4794   NoYoungRegionsClosure closure;
4795   heap_region_iterate(&closure);
4796   ret = ret && closure.success();
4797 
4798   return ret;
4799 }
4800 
4801 #endif // ASSERT
4802 
4803 class TearDownRegionSetsClosure : public HeapRegionClosure {
4804 private:
4805   HeapRegionSet *_old_set;
4806 
4807 public:
4808   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4809 
4810   bool do_heap_region(HeapRegion* r) {
4811     if (r->is_old()) {
4812       _old_set->remove(r);
4813     } else if(r->is_young()) {
4814       r->uninstall_surv_rate_group();
4815     } else {
4816       // We ignore free regions, we'll empty the free list afterwards.
4817       // We ignore humongous regions, we're not tearing down the
4818       // humongous regions set.
4819       assert(r->is_free() || r->is_humongous(),
4820              "it cannot be another type");
4821     }
4822     return false;
4823   }
4824 
4825   ~TearDownRegionSetsClosure() {
4826     assert(_old_set->is_empty(), "post-condition");
4827   }
4828 };
4829 
4830 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4831   assert_at_safepoint_on_vm_thread();
4832 
4833   if (!free_list_only) {
4834     TearDownRegionSetsClosure cl(&_old_set);
4835     heap_region_iterate(&cl);
4836 
4837     // Note that emptying the _young_list is postponed and instead done as
4838     // the first step when rebuilding the regions sets again. The reason for
4839     // this is that during a full GC string deduplication needs to know if
4840     // a collected region was young or old when the full GC was initiated.
4841   }
4842   _hrm.remove_all_free_regions();
4843 }
4844 
4845 void G1CollectedHeap::increase_used(size_t bytes) {
4846   _summary_bytes_used += bytes;
4847 }
4848 
4849 void G1CollectedHeap::decrease_used(size_t bytes) {
4850   assert(_summary_bytes_used >= bytes,
4851          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4852          _summary_bytes_used, bytes);
4853   _summary_bytes_used -= bytes;
4854 }
4855 
4856 void G1CollectedHeap::set_used(size_t bytes) {
4857   _summary_bytes_used = bytes;
4858 }
4859 
4860 class RebuildRegionSetsClosure : public HeapRegionClosure {
4861 private:
4862   bool            _free_list_only;
4863   HeapRegionSet*   _old_set;
4864   HeapRegionManager*   _hrm;
4865   size_t          _total_used;
4866 
4867 public:
4868   RebuildRegionSetsClosure(bool free_list_only,
4869                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
4870     _free_list_only(free_list_only),
4871     _old_set(old_set), _hrm(hrm), _total_used(0) {
4872     assert(_hrm->num_free_regions() == 0, "pre-condition");
4873     if (!free_list_only) {
4874       assert(_old_set->is_empty(), "pre-condition");
4875     }
4876   }
4877 
4878   bool do_heap_region(HeapRegion* r) {
4879     // After full GC, no region should have a remembered set.
4880     r->rem_set()->clear(true);
4881     if (r->is_empty()) {
4882       // Add free regions to the free list
4883       r->set_free();
4884       _hrm->insert_into_free_list(r);
4885     } else if (!_free_list_only) {
4886 
4887       if (r->is_humongous()) {
4888         // We ignore humongous regions. We left the humongous set unchanged.
4889       } else {
4890         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4891         // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
4892         r->move_to_old();
4893         _old_set->add(r);
4894       }
4895       _total_used += r->used();
4896     }
4897 
4898     return false;
4899   }
4900 
4901   size_t total_used() {
4902     return _total_used;
4903   }
4904 };
4905 
4906 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4907   assert_at_safepoint_on_vm_thread();
4908 
4909   if (!free_list_only) {
4910     _eden.clear();
4911     _survivor.clear();
4912   }
4913 
4914   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4915   heap_region_iterate(&cl);
4916 
4917   if (!free_list_only) {
4918     set_used(cl.total_used());
4919     if (_archive_allocator != NULL) {
4920       _archive_allocator->clear_used();
4921     }
4922   }
4923   assert(used_unlocked() == recalculate_used(),
4924          "inconsistent used_unlocked(), "
4925          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4926          used_unlocked(), recalculate_used());
4927 }
4928 
4929 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4930   HeapRegion* hr = heap_region_containing(p);
4931   return hr->is_in(p);
4932 }
4933 
4934 // Methods for the mutator alloc region
4935 
4936 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4937                                                       bool force) {
4938   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4939   bool should_allocate = g1_policy()->should_allocate_mutator_region();
4940   if (force || should_allocate) {
4941     HeapRegion* new_alloc_region = new_region(word_size,
4942                                               false /* is_old */,
4943                                               false /* do_expand */);
4944     if (new_alloc_region != NULL) {
4945       set_region_short_lived_locked(new_alloc_region);
4946       _hr_printer.alloc(new_alloc_region, !should_allocate);
4947       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4948       _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4949       return new_alloc_region;
4950     }
4951   }
4952   return NULL;
4953 }
4954 
4955 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4956                                                   size_t allocated_bytes) {
4957   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4958   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4959 
4960   collection_set()->add_eden_region(alloc_region);
4961   increase_used(allocated_bytes);
4962   _hr_printer.retire(alloc_region);
4963   // We update the eden sizes here, when the region is retired,
4964   // instead of when it's allocated, since this is the point that its
4965   // used space has been recored in _summary_bytes_used.
4966   g1mm()->update_eden_size();
4967 }
4968 
4969 // Methods for the GC alloc regions
4970 
4971 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4972   if (dest.is_old()) {
4973     return true;
4974   } else {
4975     return survivor_regions_count() < g1_policy()->max_survivor_regions();
4976   }
4977 }
4978 
4979 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4980   assert(FreeList_lock->owned_by_self(), "pre-condition");
4981 
4982   if (!has_more_regions(dest)) {
4983     return NULL;
4984   }
4985 
4986   const bool is_survivor = dest.is_young();
4987 
4988   HeapRegion* new_alloc_region = new_region(word_size,
4989                                             !is_survivor,
4990                                             true /* do_expand */);
4991   if (new_alloc_region != NULL) {
4992     if (is_survivor) {
4993       new_alloc_region->set_survivor();
4994       _survivor.add(new_alloc_region);
4995       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4996     } else {
4997       new_alloc_region->set_old();
4998       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4999     }
5000     _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
5001     _hr_printer.alloc(new_alloc_region);
5002     bool during_im = collector_state()->in_initial_mark_gc();
5003     new_alloc_region->note_start_of_copying(during_im);
5004     return new_alloc_region;
5005   }
5006   return NULL;
5007 }
5008 
5009 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5010                                              size_t allocated_bytes,
5011                                              InCSetState dest) {
5012   bool during_im = collector_state()->in_initial_mark_gc();
5013   alloc_region->note_end_of_copying(during_im);
5014   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5015   if (dest.is_old()) {
5016     _old_set.add(alloc_region);
5017   }
5018   _hr_printer.retire(alloc_region);
5019 }
5020 
5021 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5022   bool expanded = false;
5023   uint index = _hrm.find_highest_free(&expanded);
5024 
5025   if (index != G1_NO_HRM_INDEX) {
5026     if (expanded) {
5027       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5028                                 HeapRegion::GrainWords * HeapWordSize);
5029     }
5030     _hrm.allocate_free_regions_starting_at(index, 1);
5031     return region_at(index);
5032   }
5033   return NULL;
5034 }
5035 
5036 // Optimized nmethod scanning
5037 
5038 class RegisterNMethodOopClosure: public OopClosure {
5039   G1CollectedHeap* _g1h;
5040   nmethod* _nm;
5041 
5042   template <class T> void do_oop_work(T* p) {
5043     T heap_oop = RawAccess<>::oop_load(p);
5044     if (!CompressedOops::is_null(heap_oop)) {
5045       oop obj = CompressedOops::decode_not_null(heap_oop);
5046       HeapRegion* hr = _g1h->heap_region_containing(obj);
5047       assert(!hr->is_continues_humongous(),
5048              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5049              " starting at " HR_FORMAT,
5050              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5051 
5052       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5053       hr->add_strong_code_root_locked(_nm);
5054     }
5055   }
5056 
5057 public:
5058   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5059     _g1h(g1h), _nm(nm) {}
5060 
5061   void do_oop(oop* p)       { do_oop_work(p); }
5062   void do_oop(narrowOop* p) { do_oop_work(p); }
5063 };
5064 
5065 class UnregisterNMethodOopClosure: public OopClosure {
5066   G1CollectedHeap* _g1h;
5067   nmethod* _nm;
5068 
5069   template <class T> void do_oop_work(T* p) {
5070     T heap_oop = RawAccess<>::oop_load(p);
5071     if (!CompressedOops::is_null(heap_oop)) {
5072       oop obj = CompressedOops::decode_not_null(heap_oop);
5073       HeapRegion* hr = _g1h->heap_region_containing(obj);
5074       assert(!hr->is_continues_humongous(),
5075              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5076              " starting at " HR_FORMAT,
5077              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5078 
5079       hr->remove_strong_code_root(_nm);
5080     }
5081   }
5082 
5083 public:
5084   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5085     _g1h(g1h), _nm(nm) {}
5086 
5087   void do_oop(oop* p)       { do_oop_work(p); }
5088   void do_oop(narrowOop* p) { do_oop_work(p); }
5089 };
5090 
5091 // Returns true if the reference points to an object that
5092 // can move in an incremental collection.
5093 bool G1CollectedHeap::is_scavengable(oop obj) {
5094   HeapRegion* hr = heap_region_containing(obj);
5095   return !hr->is_pinned();
5096 }
5097 
5098 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5099   guarantee(nm != NULL, "sanity");
5100   RegisterNMethodOopClosure reg_cl(this, nm);
5101   nm->oops_do(&reg_cl);
5102 }
5103 
5104 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5105   guarantee(nm != NULL, "sanity");
5106   UnregisterNMethodOopClosure reg_cl(this, nm);
5107   nm->oops_do(&reg_cl, true);
5108 }
5109 
5110 void G1CollectedHeap::purge_code_root_memory() {
5111   double purge_start = os::elapsedTime();
5112   G1CodeRootSet::purge();
5113   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5114   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5115 }
5116 
5117 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5118   G1CollectedHeap* _g1h;
5119 
5120 public:
5121   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5122     _g1h(g1h) {}
5123 
5124   void do_code_blob(CodeBlob* cb) {
5125     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5126     if (nm == NULL) {
5127       return;
5128     }
5129 
5130     if (ScavengeRootsInCode) {
5131       _g1h->register_nmethod(nm);
5132     }
5133   }
5134 };
5135 
5136 void G1CollectedHeap::rebuild_strong_code_roots() {
5137   RebuildStrongCodeRootClosure blob_cl(this);
5138   CodeCache::blobs_do(&blob_cl);
5139 }
5140 
5141 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5142   GrowableArray<GCMemoryManager*> memory_managers(2);
5143   memory_managers.append(&_memory_manager);
5144   memory_managers.append(&_full_gc_memory_manager);
5145   return memory_managers;
5146 }
5147 
5148 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5149   GrowableArray<MemoryPool*> memory_pools(3);
5150   memory_pools.append(_eden_pool);
5151   memory_pools.append(_survivor_pool);
5152   memory_pools.append(_old_pool);
5153   return memory_pools;
5154 }