rev 53582 : imported patch rename

   1 /*
   2  * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoaderDataGraph.hpp"
  27 #include "classfile/metadataOnStackMark.hpp"
  28 #include "classfile/stringTable.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "gc/g1/g1Allocator.inline.hpp"
  32 #include "gc/g1/g1BarrierSet.hpp"
  33 #include "gc/g1/g1CollectedHeap.inline.hpp"
  34 #include "gc/g1/g1CollectionSet.hpp"
  35 #include "gc/g1/g1CollectorPolicy.hpp"
  36 #include "gc/g1/g1CollectorState.hpp"
  37 #include "gc/g1/g1ConcurrentRefine.hpp"
  38 #include "gc/g1/g1ConcurrentRefineThread.hpp"
  39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"

  40 #include "gc/g1/g1EvacStats.inline.hpp"
  41 #include "gc/g1/g1FullCollector.hpp"
  42 #include "gc/g1/g1GCPhaseTimes.hpp"
  43 #include "gc/g1/g1HeapSizingPolicy.hpp"
  44 #include "gc/g1/g1HeapTransition.hpp"
  45 #include "gc/g1/g1HeapVerifier.hpp"
  46 #include "gc/g1/g1HotCardCache.hpp"
  47 #include "gc/g1/g1MemoryPool.hpp"
  48 #include "gc/g1/g1OopClosures.inline.hpp"
  49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  50 #include "gc/g1/g1Policy.hpp"
  51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  52 #include "gc/g1/g1RemSet.hpp"
  53 #include "gc/g1/g1RootClosures.hpp"
  54 #include "gc/g1/g1RootProcessor.hpp"
  55 #include "gc/g1/g1SATBMarkQueueSet.hpp"
  56 #include "gc/g1/g1StringDedup.hpp"
  57 #include "gc/g1/g1ThreadLocalData.hpp"
  58 #include "gc/g1/g1YCTypes.hpp"
  59 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  60 #include "gc/g1/g1VMOperations.hpp"
  61 #include "gc/g1/heapRegion.inline.hpp"
  62 #include "gc/g1/heapRegionRemSet.hpp"
  63 #include "gc/g1/heapRegionSet.inline.hpp"
  64 #include "gc/shared/gcBehaviours.hpp"
  65 #include "gc/shared/gcHeapSummary.hpp"
  66 #include "gc/shared/gcId.hpp"
  67 #include "gc/shared/gcLocker.hpp"
  68 #include "gc/shared/gcTimer.hpp"
  69 #include "gc/shared/gcTrace.hpp"
  70 #include "gc/shared/gcTraceTime.inline.hpp"
  71 #include "gc/shared/generationSpec.hpp"
  72 #include "gc/shared/isGCActiveMark.hpp"
  73 #include "gc/shared/oopStorageParState.hpp"
  74 #include "gc/shared/parallelCleaning.hpp"
  75 #include "gc/shared/preservedMarks.inline.hpp"
  76 #include "gc/shared/suspendibleThreadSet.hpp"
  77 #include "gc/shared/referenceProcessor.inline.hpp"
  78 #include "gc/shared/taskqueue.inline.hpp"
  79 #include "gc/shared/weakProcessor.inline.hpp"
  80 #include "gc/shared/workerPolicy.hpp"
  81 #include "logging/log.hpp"
  82 #include "memory/allocation.hpp"
  83 #include "memory/iterator.hpp"
  84 #include "memory/resourceArea.hpp"
  85 #include "oops/access.inline.hpp"
  86 #include "oops/compressedOops.inline.hpp"
  87 #include "oops/oop.inline.hpp"
  88 #include "runtime/atomic.hpp"
  89 #include "runtime/flags/flagSetting.hpp"
  90 #include "runtime/handles.inline.hpp"
  91 #include "runtime/init.hpp"
  92 #include "runtime/orderAccess.hpp"
  93 #include "runtime/threadSMR.hpp"
  94 #include "runtime/vmThread.hpp"
  95 #include "utilities/align.hpp"
  96 #include "utilities/globalDefinitions.hpp"
  97 #include "utilities/stack.inline.hpp"
  98 
  99 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
 100 
 101 // INVARIANTS/NOTES
 102 //
 103 // All allocation activity covered by the G1CollectedHeap interface is
 104 // serialized by acquiring the HeapLock.  This happens in mem_allocate
 105 // and allocate_new_tlab, which are the "entry" points to the
 106 // allocation code from the rest of the JVM.  (Note that this does not
 107 // apply to TLAB allocation, which is not part of this interface: it
 108 // is done by clients of this interface.)
 109 
 110 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 111  private:
 112   size_t _num_dirtied;
 113   G1CollectedHeap* _g1h;
 114   G1CardTable* _g1_ct;
 115 
 116   HeapRegion* region_for_card(jbyte* card_ptr) const {
 117     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
 118   }
 119 
 120   bool will_become_free(HeapRegion* hr) const {
 121     // A region will be freed by free_collection_set if the region is in the
 122     // collection set and has not had an evacuation failure.
 123     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 124   }
 125 
 126  public:
 127   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 128     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
 129 
 130   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 131     HeapRegion* hr = region_for_card(card_ptr);
 132 
 133     // Should only dirty cards in regions that won't be freed.
 134     if (!will_become_free(hr)) {
 135       *card_ptr = G1CardTable::dirty_card_val();
 136       _num_dirtied++;
 137     }
 138 
 139     return true;
 140   }
 141 
 142   size_t num_dirtied()   const { return _num_dirtied; }
 143 };
 144 
 145 
 146 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 147   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 148 }
 149 
 150 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 151   // The from card cache is not the memory that is actually committed. So we cannot
 152   // take advantage of the zero_filled parameter.
 153   reset_from_card_cache(start_idx, num_regions);
 154 }
 155 
 156 
 157 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 158                                              MemRegion mr) {
 159   return new HeapRegion(hrs_index, bot(), mr);
 160 }
 161 
 162 // Private methods.
 163 
 164 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) {
 165   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 166          "the only time we use this to allocate a humongous region is "
 167          "when we are allocating a single humongous region");
 168 
 169   HeapRegion* res = _hrm->allocate_free_region(type);
 170 
 171   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 172     // Currently, only attempts to allocate GC alloc regions set
 173     // do_expand to true. So, we should only reach here during a
 174     // safepoint. If this assumption changes we might have to
 175     // reconsider the use of _expand_heap_after_alloc_failure.
 176     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 177 
 178     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 179                               word_size * HeapWordSize);
 180 
 181     if (expand(word_size * HeapWordSize)) {
 182       // Given that expand() succeeded in expanding the heap, and we
 183       // always expand the heap by an amount aligned to the heap
 184       // region size, the free list should in theory not be empty.
 185       // In either case allocate_free_region() will check for NULL.
 186       res = _hrm->allocate_free_region(type);
 187     } else {
 188       _expand_heap_after_alloc_failure = false;
 189     }
 190   }
 191   return res;
 192 }
 193 
 194 HeapWord*
 195 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 196                                                            uint num_regions,
 197                                                            size_t word_size) {
 198   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 199   assert(is_humongous(word_size), "word_size should be humongous");
 200   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 201 
 202   // Index of last region in the series.
 203   uint last = first + num_regions - 1;
 204 
 205   // We need to initialize the region(s) we just discovered. This is
 206   // a bit tricky given that it can happen concurrently with
 207   // refinement threads refining cards on these regions and
 208   // potentially wanting to refine the BOT as they are scanning
 209   // those cards (this can happen shortly after a cleanup; see CR
 210   // 6991377). So we have to set up the region(s) carefully and in
 211   // a specific order.
 212 
 213   // The word size sum of all the regions we will allocate.
 214   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 215   assert(word_size <= word_size_sum, "sanity");
 216 
 217   // This will be the "starts humongous" region.
 218   HeapRegion* first_hr = region_at(first);
 219   // The header of the new object will be placed at the bottom of
 220   // the first region.
 221   HeapWord* new_obj = first_hr->bottom();
 222   // This will be the new top of the new object.
 223   HeapWord* obj_top = new_obj + word_size;
 224 
 225   // First, we need to zero the header of the space that we will be
 226   // allocating. When we update top further down, some refinement
 227   // threads might try to scan the region. By zeroing the header we
 228   // ensure that any thread that will try to scan the region will
 229   // come across the zero klass word and bail out.
 230   //
 231   // NOTE: It would not have been correct to have used
 232   // CollectedHeap::fill_with_object() and make the space look like
 233   // an int array. The thread that is doing the allocation will
 234   // later update the object header to a potentially different array
 235   // type and, for a very short period of time, the klass and length
 236   // fields will be inconsistent. This could cause a refinement
 237   // thread to calculate the object size incorrectly.
 238   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 239 
 240   // Next, pad out the unused tail of the last region with filler
 241   // objects, for improved usage accounting.
 242   // How many words we use for filler objects.
 243   size_t word_fill_size = word_size_sum - word_size;
 244 
 245   // How many words memory we "waste" which cannot hold a filler object.
 246   size_t words_not_fillable = 0;
 247 
 248   if (word_fill_size >= min_fill_size()) {
 249     fill_with_objects(obj_top, word_fill_size);
 250   } else if (word_fill_size > 0) {
 251     // We have space to fill, but we cannot fit an object there.
 252     words_not_fillable = word_fill_size;
 253     word_fill_size = 0;
 254   }
 255 
 256   // We will set up the first region as "starts humongous". This
 257   // will also update the BOT covering all the regions to reflect
 258   // that there is a single object that starts at the bottom of the
 259   // first region.
 260   first_hr->set_starts_humongous(obj_top, word_fill_size);
 261   _g1_policy->remset_tracker()->update_at_allocate(first_hr);
 262   // Then, if there are any, we will set up the "continues
 263   // humongous" regions.
 264   HeapRegion* hr = NULL;
 265   for (uint i = first + 1; i <= last; ++i) {
 266     hr = region_at(i);
 267     hr->set_continues_humongous(first_hr);
 268     _g1_policy->remset_tracker()->update_at_allocate(hr);
 269   }
 270 
 271   // Up to this point no concurrent thread would have been able to
 272   // do any scanning on any region in this series. All the top
 273   // fields still point to bottom, so the intersection between
 274   // [bottom,top] and [card_start,card_end] will be empty. Before we
 275   // update the top fields, we'll do a storestore to make sure that
 276   // no thread sees the update to top before the zeroing of the
 277   // object header and the BOT initialization.
 278   OrderAccess::storestore();
 279 
 280   // Now, we will update the top fields of the "continues humongous"
 281   // regions except the last one.
 282   for (uint i = first; i < last; ++i) {
 283     hr = region_at(i);
 284     hr->set_top(hr->end());
 285   }
 286 
 287   hr = region_at(last);
 288   // If we cannot fit a filler object, we must set top to the end
 289   // of the humongous object, otherwise we cannot iterate the heap
 290   // and the BOT will not be complete.
 291   hr->set_top(hr->end() - words_not_fillable);
 292 
 293   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 294          "obj_top should be in last region");
 295 
 296   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 297 
 298   assert(words_not_fillable == 0 ||
 299          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 300          "Miscalculation in humongous allocation");
 301 
 302   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 303 
 304   for (uint i = first; i <= last; ++i) {
 305     hr = region_at(i);
 306     _humongous_set.add(hr);
 307     _hr_printer.alloc(hr);
 308   }
 309 
 310   return new_obj;
 311 }
 312 
 313 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 314   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 315   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 316 }
 317 
 318 // If could fit into free regions w/o expansion, try.
 319 // Otherwise, if can expand, do so.
 320 // Otherwise, if using ex regions might help, try with ex given back.
 321 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 322   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 323 
 324   _verifier->verify_region_sets_optional();
 325 
 326   uint first = G1_NO_HRM_INDEX;
 327   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 328 
 329   if (obj_regions == 1) {
 330     // Only one region to allocate, try to use a fast path by directly allocating
 331     // from the free lists. Do not try to expand here, we will potentially do that
 332     // later.
 333     HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
 334     if (hr != NULL) {
 335       first = hr->hrm_index();
 336     }
 337   } else {
 338     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 339     // are lucky enough to find some.
 340     first = _hrm->find_contiguous_only_empty(obj_regions);
 341     if (first != G1_NO_HRM_INDEX) {
 342       _hrm->allocate_free_regions_starting_at(first, obj_regions);
 343     }
 344   }
 345 
 346   if (first == G1_NO_HRM_INDEX) {
 347     // Policy: We could not find enough regions for the humongous object in the
 348     // free list. Look through the heap to find a mix of free and uncommitted regions.
 349     // If so, try expansion.
 350     first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
 351     if (first != G1_NO_HRM_INDEX) {
 352       // We found something. Make sure these regions are committed, i.e. expand
 353       // the heap. Alternatively we could do a defragmentation GC.
 354       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 355                                     word_size * HeapWordSize);
 356 
 357       _hrm->expand_at(first, obj_regions, workers());
 358       g1_policy()->record_new_heap_size(num_regions());
 359 
 360 #ifdef ASSERT
 361       for (uint i = first; i < first + obj_regions; ++i) {
 362         HeapRegion* hr = region_at(i);
 363         assert(hr->is_free(), "sanity");
 364         assert(hr->is_empty(), "sanity");
 365         assert(is_on_master_free_list(hr), "sanity");
 366       }
 367 #endif
 368       _hrm->allocate_free_regions_starting_at(first, obj_regions);
 369     } else {
 370       // Policy: Potentially trigger a defragmentation GC.
 371     }
 372   }
 373 
 374   HeapWord* result = NULL;
 375   if (first != G1_NO_HRM_INDEX) {
 376     result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
 377     assert(result != NULL, "it should always return a valid result");
 378 
 379     // A successful humongous object allocation changes the used space
 380     // information of the old generation so we need to recalculate the
 381     // sizes and update the jstat counters here.
 382     g1mm()->update_sizes();
 383   }
 384 
 385   _verifier->verify_region_sets_optional();
 386 
 387   return result;
 388 }
 389 
 390 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
 391                                              size_t requested_size,
 392                                              size_t* actual_size) {
 393   assert_heap_not_locked_and_not_at_safepoint();
 394   assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
 395 
 396   return attempt_allocation(min_size, requested_size, actual_size);
 397 }
 398 
 399 HeapWord*
 400 G1CollectedHeap::mem_allocate(size_t word_size,
 401                               bool*  gc_overhead_limit_was_exceeded) {
 402   assert_heap_not_locked_and_not_at_safepoint();
 403 
 404   if (is_humongous(word_size)) {
 405     return attempt_allocation_humongous(word_size);
 406   }
 407   size_t dummy = 0;
 408   return attempt_allocation(word_size, word_size, &dummy);
 409 }
 410 
 411 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 412   ResourceMark rm; // For retrieving the thread names in log messages.
 413 
 414   // Make sure you read the note in attempt_allocation_humongous().
 415 
 416   assert_heap_not_locked_and_not_at_safepoint();
 417   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 418          "be called for humongous allocation requests");
 419 
 420   // We should only get here after the first-level allocation attempt
 421   // (attempt_allocation()) failed to allocate.
 422 
 423   // We will loop until a) we manage to successfully perform the
 424   // allocation or b) we successfully schedule a collection which
 425   // fails to perform the allocation. b) is the only case when we'll
 426   // return NULL.
 427   HeapWord* result = NULL;
 428   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 429     bool should_try_gc;
 430     uint gc_count_before;
 431 
 432     {
 433       MutexLockerEx x(Heap_lock);
 434       result = _allocator->attempt_allocation_locked(word_size);
 435       if (result != NULL) {
 436         return result;
 437       }
 438 
 439       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 440       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 441       // waiting because the GCLocker is active to not wait too long.
 442       if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
 443         // No need for an ergo message here, can_expand_young_list() does this when
 444         // it returns true.
 445         result = _allocator->attempt_allocation_force(word_size);
 446         if (result != NULL) {
 447           return result;
 448         }
 449       }
 450       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 451       // the GCLocker initiated GC has been performed and then retry. This includes
 452       // the case when the GC Locker is not active but has not been performed.
 453       should_try_gc = !GCLocker::needs_gc();
 454       // Read the GC count while still holding the Heap_lock.
 455       gc_count_before = total_collections();
 456     }
 457 
 458     if (should_try_gc) {
 459       bool succeeded;
 460       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 461                                    GCCause::_g1_inc_collection_pause);
 462       if (result != NULL) {
 463         assert(succeeded, "only way to get back a non-NULL result");
 464         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 465                              Thread::current()->name(), p2i(result));
 466         return result;
 467       }
 468 
 469       if (succeeded) {
 470         // We successfully scheduled a collection which failed to allocate. No
 471         // point in trying to allocate further. We'll just return NULL.
 472         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 473                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 474         return NULL;
 475       }
 476       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 477                            Thread::current()->name(), word_size);
 478     } else {
 479       // Failed to schedule a collection.
 480       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 481         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 482                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 483         return NULL;
 484       }
 485       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 486       // The GCLocker is either active or the GCLocker initiated
 487       // GC has not yet been performed. Stall until it is and
 488       // then retry the allocation.
 489       GCLocker::stall_until_clear();
 490       gclocker_retry_count += 1;
 491     }
 492 
 493     // We can reach here if we were unsuccessful in scheduling a
 494     // collection (because another thread beat us to it) or if we were
 495     // stalled due to the GC locker. In either can we should retry the
 496     // allocation attempt in case another thread successfully
 497     // performed a collection and reclaimed enough space. We do the
 498     // first attempt (without holding the Heap_lock) here and the
 499     // follow-on attempt will be at the start of the next loop
 500     // iteration (after taking the Heap_lock).
 501     size_t dummy = 0;
 502     result = _allocator->attempt_allocation(word_size, word_size, &dummy);
 503     if (result != NULL) {
 504       return result;
 505     }
 506 
 507     // Give a warning if we seem to be looping forever.
 508     if ((QueuedAllocationWarningCount > 0) &&
 509         (try_count % QueuedAllocationWarningCount == 0)) {
 510       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 511                              Thread::current()->name(), try_count, word_size);
 512     }
 513   }
 514 
 515   ShouldNotReachHere();
 516   return NULL;
 517 }
 518 
 519 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 520   assert_at_safepoint_on_vm_thread();
 521   if (_archive_allocator == NULL) {
 522     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 523   }
 524 }
 525 
 526 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 527   // Allocations in archive regions cannot be of a size that would be considered
 528   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 529   // may be different at archive-restore time.
 530   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 531 }
 532 
 533 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 534   assert_at_safepoint_on_vm_thread();
 535   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 536   if (is_archive_alloc_too_large(word_size)) {
 537     return NULL;
 538   }
 539   return _archive_allocator->archive_mem_allocate(word_size);
 540 }
 541 
 542 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 543                                               size_t end_alignment_in_bytes) {
 544   assert_at_safepoint_on_vm_thread();
 545   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 546 
 547   // Call complete_archive to do the real work, filling in the MemRegion
 548   // array with the archive regions.
 549   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 550   delete _archive_allocator;
 551   _archive_allocator = NULL;
 552 }
 553 
 554 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 555   assert(ranges != NULL, "MemRegion array NULL");
 556   assert(count != 0, "No MemRegions provided");
 557   MemRegion reserved = _hrm->reserved();
 558   for (size_t i = 0; i < count; i++) {
 559     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 560       return false;
 561     }
 562   }
 563   return true;
 564 }
 565 
 566 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 567                                             size_t count,
 568                                             bool open) {
 569   assert(!is_init_completed(), "Expect to be called at JVM init time");
 570   assert(ranges != NULL, "MemRegion array NULL");
 571   assert(count != 0, "No MemRegions provided");
 572   MutexLockerEx x(Heap_lock);
 573 
 574   MemRegion reserved = _hrm->reserved();
 575   HeapWord* prev_last_addr = NULL;
 576   HeapRegion* prev_last_region = NULL;
 577 
 578   // Temporarily disable pretouching of heap pages. This interface is used
 579   // when mmap'ing archived heap data in, so pre-touching is wasted.
 580   FlagSetting fs(AlwaysPreTouch, false);
 581 
 582   // Enable archive object checking used by G1MarkSweep. We have to let it know
 583   // about each archive range, so that objects in those ranges aren't marked.
 584   G1ArchiveAllocator::enable_archive_object_check();
 585 
 586   // For each specified MemRegion range, allocate the corresponding G1
 587   // regions and mark them as archive regions. We expect the ranges
 588   // in ascending starting address order, without overlap.
 589   for (size_t i = 0; i < count; i++) {
 590     MemRegion curr_range = ranges[i];
 591     HeapWord* start_address = curr_range.start();
 592     size_t word_size = curr_range.word_size();
 593     HeapWord* last_address = curr_range.last();
 594     size_t commits = 0;
 595 
 596     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 597               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 598               p2i(start_address), p2i(last_address));
 599     guarantee(start_address > prev_last_addr,
 600               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 601               p2i(start_address), p2i(prev_last_addr));
 602     prev_last_addr = last_address;
 603 
 604     // Check for ranges that start in the same G1 region in which the previous
 605     // range ended, and adjust the start address so we don't try to allocate
 606     // the same region again. If the current range is entirely within that
 607     // region, skip it, just adjusting the recorded top.
 608     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 609     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 610       start_address = start_region->end();
 611       if (start_address > last_address) {
 612         increase_used(word_size * HeapWordSize);
 613         start_region->set_top(last_address + 1);
 614         continue;
 615       }
 616       start_region->set_top(start_address);
 617       curr_range = MemRegion(start_address, last_address + 1);
 618       start_region = _hrm->addr_to_region(start_address);
 619     }
 620 
 621     // Perform the actual region allocation, exiting if it fails.
 622     // Then note how much new space we have allocated.
 623     if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
 624       return false;
 625     }
 626     increase_used(word_size * HeapWordSize);
 627     if (commits != 0) {
 628       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 629                                 HeapRegion::GrainWords * HeapWordSize * commits);
 630 
 631     }
 632 
 633     // Mark each G1 region touched by the range as archive, add it to
 634     // the old set, and set top.
 635     HeapRegion* curr_region = _hrm->addr_to_region(start_address);
 636     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 637     prev_last_region = last_region;
 638 
 639     while (curr_region != NULL) {
 640       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 641              "Region already in use (index %u)", curr_region->hrm_index());
 642       if (open) {
 643         curr_region->set_open_archive();
 644       } else {
 645         curr_region->set_closed_archive();
 646       }
 647       _hr_printer.alloc(curr_region);
 648       _archive_set.add(curr_region);
 649       HeapWord* top;
 650       HeapRegion* next_region;
 651       if (curr_region != last_region) {
 652         top = curr_region->end();
 653         next_region = _hrm->next_region_in_heap(curr_region);
 654       } else {
 655         top = last_address + 1;
 656         next_region = NULL;
 657       }
 658       curr_region->set_top(top);
 659       curr_region->set_first_dead(top);
 660       curr_region->set_end_of_live(top);
 661       curr_region = next_region;
 662     }
 663 
 664     // Notify mark-sweep of the archive
 665     G1ArchiveAllocator::set_range_archive(curr_range, open);
 666   }
 667   return true;
 668 }
 669 
 670 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 671   assert(!is_init_completed(), "Expect to be called at JVM init time");
 672   assert(ranges != NULL, "MemRegion array NULL");
 673   assert(count != 0, "No MemRegions provided");
 674   MemRegion reserved = _hrm->reserved();
 675   HeapWord *prev_last_addr = NULL;
 676   HeapRegion* prev_last_region = NULL;
 677 
 678   // For each MemRegion, create filler objects, if needed, in the G1 regions
 679   // that contain the address range. The address range actually within the
 680   // MemRegion will not be modified. That is assumed to have been initialized
 681   // elsewhere, probably via an mmap of archived heap data.
 682   MutexLockerEx x(Heap_lock);
 683   for (size_t i = 0; i < count; i++) {
 684     HeapWord* start_address = ranges[i].start();
 685     HeapWord* last_address = ranges[i].last();
 686 
 687     assert(reserved.contains(start_address) && reserved.contains(last_address),
 688            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 689            p2i(start_address), p2i(last_address));
 690     assert(start_address > prev_last_addr,
 691            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 692            p2i(start_address), p2i(prev_last_addr));
 693 
 694     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 695     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 696     HeapWord* bottom_address = start_region->bottom();
 697 
 698     // Check for a range beginning in the same region in which the
 699     // previous one ended.
 700     if (start_region == prev_last_region) {
 701       bottom_address = prev_last_addr + 1;
 702     }
 703 
 704     // Verify that the regions were all marked as archive regions by
 705     // alloc_archive_regions.
 706     HeapRegion* curr_region = start_region;
 707     while (curr_region != NULL) {
 708       guarantee(curr_region->is_archive(),
 709                 "Expected archive region at index %u", curr_region->hrm_index());
 710       if (curr_region != last_region) {
 711         curr_region = _hrm->next_region_in_heap(curr_region);
 712       } else {
 713         curr_region = NULL;
 714       }
 715     }
 716 
 717     prev_last_addr = last_address;
 718     prev_last_region = last_region;
 719 
 720     // Fill the memory below the allocated range with dummy object(s),
 721     // if the region bottom does not match the range start, or if the previous
 722     // range ended within the same G1 region, and there is a gap.
 723     if (start_address != bottom_address) {
 724       size_t fill_size = pointer_delta(start_address, bottom_address);
 725       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 726       increase_used(fill_size * HeapWordSize);
 727     }
 728   }
 729 }
 730 
 731 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
 732                                                      size_t desired_word_size,
 733                                                      size_t* actual_word_size) {
 734   assert_heap_not_locked_and_not_at_safepoint();
 735   assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
 736          "be called for humongous allocation requests");
 737 
 738   HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
 739 
 740   if (result == NULL) {
 741     *actual_word_size = desired_word_size;
 742     result = attempt_allocation_slow(desired_word_size);
 743   }
 744 
 745   assert_heap_not_locked();
 746   if (result != NULL) {
 747     assert(*actual_word_size != 0, "Actual size must have been set here");
 748     dirty_young_block(result, *actual_word_size);
 749   } else {
 750     *actual_word_size = 0;
 751   }
 752 
 753   return result;
 754 }
 755 
 756 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
 757   assert(!is_init_completed(), "Expect to be called at JVM init time");
 758   assert(ranges != NULL, "MemRegion array NULL");
 759   assert(count != 0, "No MemRegions provided");
 760   MemRegion reserved = _hrm->reserved();
 761   HeapWord* prev_last_addr = NULL;
 762   HeapRegion* prev_last_region = NULL;
 763   size_t size_used = 0;
 764   size_t uncommitted_regions = 0;
 765 
 766   // For each Memregion, free the G1 regions that constitute it, and
 767   // notify mark-sweep that the range is no longer to be considered 'archive.'
 768   MutexLockerEx x(Heap_lock);
 769   for (size_t i = 0; i < count; i++) {
 770     HeapWord* start_address = ranges[i].start();
 771     HeapWord* last_address = ranges[i].last();
 772 
 773     assert(reserved.contains(start_address) && reserved.contains(last_address),
 774            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 775            p2i(start_address), p2i(last_address));
 776     assert(start_address > prev_last_addr,
 777            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 778            p2i(start_address), p2i(prev_last_addr));
 779     size_used += ranges[i].byte_size();
 780     prev_last_addr = last_address;
 781 
 782     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 783     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 784 
 785     // Check for ranges that start in the same G1 region in which the previous
 786     // range ended, and adjust the start address so we don't try to free
 787     // the same region again. If the current range is entirely within that
 788     // region, skip it.
 789     if (start_region == prev_last_region) {
 790       start_address = start_region->end();
 791       if (start_address > last_address) {
 792         continue;
 793       }
 794       start_region = _hrm->addr_to_region(start_address);
 795     }
 796     prev_last_region = last_region;
 797 
 798     // After verifying that each region was marked as an archive region by
 799     // alloc_archive_regions, set it free and empty and uncommit it.
 800     HeapRegion* curr_region = start_region;
 801     while (curr_region != NULL) {
 802       guarantee(curr_region->is_archive(),
 803                 "Expected archive region at index %u", curr_region->hrm_index());
 804       uint curr_index = curr_region->hrm_index();
 805       _archive_set.remove(curr_region);
 806       curr_region->set_free();
 807       curr_region->set_top(curr_region->bottom());
 808       if (curr_region != last_region) {
 809         curr_region = _hrm->next_region_in_heap(curr_region);
 810       } else {
 811         curr_region = NULL;
 812       }
 813       _hrm->shrink_at(curr_index, 1);
 814       uncommitted_regions++;
 815     }
 816 
 817     // Notify mark-sweep that this is no longer an archive range.
 818     G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
 819   }
 820 
 821   if (uncommitted_regions != 0) {
 822     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 823                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 824   }
 825   decrease_used(size_used);
 826 }
 827 
 828 oop G1CollectedHeap::materialize_archived_object(oop obj) {
 829   assert(obj != NULL, "archived obj is NULL");
 830   assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
 831 
 832   // Loading an archived object makes it strongly reachable. If it is
 833   // loaded during concurrent marking, it must be enqueued to the SATB
 834   // queue, shading the previously white object gray.
 835   G1BarrierSet::enqueue(obj);
 836 
 837   return obj;
 838 }
 839 
 840 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 841   ResourceMark rm; // For retrieving the thread names in log messages.
 842 
 843   // The structure of this method has a lot of similarities to
 844   // attempt_allocation_slow(). The reason these two were not merged
 845   // into a single one is that such a method would require several "if
 846   // allocation is not humongous do this, otherwise do that"
 847   // conditional paths which would obscure its flow. In fact, an early
 848   // version of this code did use a unified method which was harder to
 849   // follow and, as a result, it had subtle bugs that were hard to
 850   // track down. So keeping these two methods separate allows each to
 851   // be more readable. It will be good to keep these two in sync as
 852   // much as possible.
 853 
 854   assert_heap_not_locked_and_not_at_safepoint();
 855   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 856          "should only be called for humongous allocations");
 857 
 858   // Humongous objects can exhaust the heap quickly, so we should check if we
 859   // need to start a marking cycle at each humongous object allocation. We do
 860   // the check before we do the actual allocation. The reason for doing it
 861   // before the allocation is that we avoid having to keep track of the newly
 862   // allocated memory while we do a GC.
 863   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 864                                            word_size)) {
 865     collect(GCCause::_g1_humongous_allocation);
 866   }
 867 
 868   // We will loop until a) we manage to successfully perform the
 869   // allocation or b) we successfully schedule a collection which
 870   // fails to perform the allocation. b) is the only case when we'll
 871   // return NULL.
 872   HeapWord* result = NULL;
 873   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 874     bool should_try_gc;
 875     uint gc_count_before;
 876 
 877 
 878     {
 879       MutexLockerEx x(Heap_lock);
 880 
 881       // Given that humongous objects are not allocated in young
 882       // regions, we'll first try to do the allocation without doing a
 883       // collection hoping that there's enough space in the heap.
 884       result = humongous_obj_allocate(word_size);
 885       if (result != NULL) {
 886         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 887         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 888         return result;
 889       }
 890 
 891       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 892       // the GCLocker initiated GC has been performed and then retry. This includes
 893       // the case when the GC Locker is not active but has not been performed.
 894       should_try_gc = !GCLocker::needs_gc();
 895       // Read the GC count while still holding the Heap_lock.
 896       gc_count_before = total_collections();
 897     }
 898 
 899     if (should_try_gc) {
 900       bool succeeded;
 901       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 902                                    GCCause::_g1_humongous_allocation);
 903       if (result != NULL) {
 904         assert(succeeded, "only way to get back a non-NULL result");
 905         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 906                              Thread::current()->name(), p2i(result));
 907         return result;
 908       }
 909 
 910       if (succeeded) {
 911         // We successfully scheduled a collection which failed to allocate. No
 912         // point in trying to allocate further. We'll just return NULL.
 913         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 914                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 915         return NULL;
 916       }
 917       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 918                            Thread::current()->name(), word_size);
 919     } else {
 920       // Failed to schedule a collection.
 921       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 922         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 923                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 924         return NULL;
 925       }
 926       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 927       // The GCLocker is either active or the GCLocker initiated
 928       // GC has not yet been performed. Stall until it is and
 929       // then retry the allocation.
 930       GCLocker::stall_until_clear();
 931       gclocker_retry_count += 1;
 932     }
 933 
 934 
 935     // We can reach here if we were unsuccessful in scheduling a
 936     // collection (because another thread beat us to it) or if we were
 937     // stalled due to the GC locker. In either can we should retry the
 938     // allocation attempt in case another thread successfully
 939     // performed a collection and reclaimed enough space.
 940     // Humongous object allocation always needs a lock, so we wait for the retry
 941     // in the next iteration of the loop, unlike for the regular iteration case.
 942     // Give a warning if we seem to be looping forever.
 943 
 944     if ((QueuedAllocationWarningCount > 0) &&
 945         (try_count % QueuedAllocationWarningCount == 0)) {
 946       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 947                              Thread::current()->name(), try_count, word_size);
 948     }
 949   }
 950 
 951   ShouldNotReachHere();
 952   return NULL;
 953 }
 954 
 955 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 956                                                            bool expect_null_mutator_alloc_region) {
 957   assert_at_safepoint_on_vm_thread();
 958   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 959          "the current alloc region was unexpectedly found to be non-NULL");
 960 
 961   if (!is_humongous(word_size)) {
 962     return _allocator->attempt_allocation_locked(word_size);
 963   } else {
 964     HeapWord* result = humongous_obj_allocate(word_size);
 965     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
 966       collector_state()->set_initiate_conc_mark_if_possible(true);
 967     }
 968     return result;
 969   }
 970 
 971   ShouldNotReachHere();
 972 }
 973 
 974 class PostCompactionPrinterClosure: public HeapRegionClosure {
 975 private:
 976   G1HRPrinter* _hr_printer;
 977 public:
 978   bool do_heap_region(HeapRegion* hr) {
 979     assert(!hr->is_young(), "not expecting to find young regions");
 980     _hr_printer->post_compaction(hr);
 981     return false;
 982   }
 983 
 984   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 985     : _hr_printer(hr_printer) { }
 986 };
 987 
 988 void G1CollectedHeap::print_hrm_post_compaction() {
 989   if (_hr_printer.is_active()) {
 990     PostCompactionPrinterClosure cl(hr_printer());
 991     heap_region_iterate(&cl);
 992   }
 993 }
 994 
 995 void G1CollectedHeap::abort_concurrent_cycle() {
 996   // If we start the compaction before the CM threads finish
 997   // scanning the root regions we might trip them over as we'll
 998   // be moving objects / updating references. So let's wait until
 999   // they are done. By telling them to abort, they should complete
1000   // early.
1001   _cm->root_regions()->abort();
1002   _cm->root_regions()->wait_until_scan_finished();
1003 
1004   // Disable discovery and empty the discovered lists
1005   // for the CM ref processor.
1006   _ref_processor_cm->disable_discovery();
1007   _ref_processor_cm->abandon_partial_discovery();
1008   _ref_processor_cm->verify_no_references_recorded();
1009 
1010   // Abandon current iterations of concurrent marking and concurrent
1011   // refinement, if any are in progress.
1012   concurrent_mark()->concurrent_cycle_abort();
1013 }
1014 
1015 void G1CollectedHeap::prepare_heap_for_full_collection() {
1016   // Make sure we'll choose a new allocation region afterwards.
1017   _allocator->release_mutator_alloc_region();
1018   _allocator->abandon_gc_alloc_regions();
1019 
1020   // We may have added regions to the current incremental collection
1021   // set between the last GC or pause and now. We need to clear the
1022   // incremental collection set and then start rebuilding it afresh
1023   // after this full GC.
1024   abandon_collection_set(collection_set());
1025 
1026   tear_down_region_sets(false /* free_list_only */);
1027 
1028   hrm()->prepare_for_full_collection_start();
1029 }
1030 
1031 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1032   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1033   assert(used() == recalculate_used(), "Should be equal");
1034   _verifier->verify_region_sets_optional();
1035   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1036   _verifier->check_bitmaps("Full GC Start");
1037 }
1038 
1039 void G1CollectedHeap::prepare_heap_for_mutators() {
1040   hrm()->prepare_for_full_collection_end();
1041 
1042   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1043   ClassLoaderDataGraph::purge();
1044   MetaspaceUtils::verify_metrics();
1045 
1046   // Prepare heap for normal collections.
1047   assert(num_free_regions() == 0, "we should not have added any free regions");
1048   rebuild_region_sets(false /* free_list_only */);
1049   abort_refinement();
1050   resize_heap_if_necessary();
1051 
1052   // Rebuild the strong code root lists for each region
1053   rebuild_strong_code_roots();
1054 
1055   // Purge code root memory
1056   purge_code_root_memory();
1057 
1058   // Start a new incremental collection set for the next pause
1059   start_new_collection_set();
1060 
1061   _allocator->init_mutator_alloc_region();
1062 
1063   // Post collection state updates.
1064   MetaspaceGC::compute_new_size();
1065 }
1066 
1067 void G1CollectedHeap::abort_refinement() {
1068   if (_hot_card_cache->use_cache()) {
1069     _hot_card_cache->reset_hot_cache();
1070   }
1071 
1072   // Discard all remembered set updates.
1073   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1074   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1075 }
1076 
1077 void G1CollectedHeap::verify_after_full_collection() {
1078   _hrm->verify_optional();
1079   _verifier->verify_region_sets_optional();
1080   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1081   // Clear the previous marking bitmap, if needed for bitmap verification.
1082   // Note we cannot do this when we clear the next marking bitmap in
1083   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1084   // objects marked during a full GC against the previous bitmap.
1085   // But we need to clear it before calling check_bitmaps below since
1086   // the full GC has compacted objects and updated TAMS but not updated
1087   // the prev bitmap.
1088   if (G1VerifyBitmaps) {
1089     GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification");
1090     _cm->clear_prev_bitmap(workers());
1091   }
1092   // This call implicitly verifies that the next bitmap is clear after Full GC.
1093   _verifier->check_bitmaps("Full GC End");
1094 
1095   // At this point there should be no regions in the
1096   // entire heap tagged as young.
1097   assert(check_young_list_empty(), "young list should be empty at this point");
1098 
1099   // Note: since we've just done a full GC, concurrent
1100   // marking is no longer active. Therefore we need not
1101   // re-enable reference discovery for the CM ref processor.
1102   // That will be done at the start of the next marking cycle.
1103   // We also know that the STW processor should no longer
1104   // discover any new references.
1105   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1106   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1107   _ref_processor_stw->verify_no_references_recorded();
1108   _ref_processor_cm->verify_no_references_recorded();
1109 }
1110 
1111 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1112   // Post collection logging.
1113   // We should do this after we potentially resize the heap so
1114   // that all the COMMIT / UNCOMMIT events are generated before
1115   // the compaction events.
1116   print_hrm_post_compaction();
1117   heap_transition->print();
1118   print_heap_after_gc();
1119   print_heap_regions();
1120 #ifdef TRACESPINNING
1121   ParallelTaskTerminator::print_termination_counts();
1122 #endif
1123 }
1124 
1125 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1126                                          bool clear_all_soft_refs) {
1127   assert_at_safepoint_on_vm_thread();
1128 
1129   if (GCLocker::check_active_before_gc()) {
1130     // Full GC was not completed.
1131     return false;
1132   }
1133 
1134   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1135       soft_ref_policy()->should_clear_all_soft_refs();
1136 
1137   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1138   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1139 
1140   collector.prepare_collection();
1141   collector.collect();
1142   collector.complete_collection();
1143 
1144   // Full collection was successfully completed.
1145   return true;
1146 }
1147 
1148 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1149   // Currently, there is no facility in the do_full_collection(bool) API to notify
1150   // the caller that the collection did not succeed (e.g., because it was locked
1151   // out by the GC locker). So, right now, we'll ignore the return value.
1152   bool dummy = do_full_collection(true,                /* explicit_gc */
1153                                   clear_all_soft_refs);
1154 }
1155 
1156 void G1CollectedHeap::resize_heap_if_necessary() {
1157   assert_at_safepoint_on_vm_thread();
1158 
1159   // Capacity, free and used after the GC counted as full regions to
1160   // include the waste in the following calculations.
1161   const size_t capacity_after_gc = capacity();
1162   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1163 
1164   // This is enforced in arguments.cpp.
1165   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1166          "otherwise the code below doesn't make sense");
1167 
1168   // We don't have floating point command-line arguments
1169   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1170   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1171   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1172   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1173 
1174   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1175   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1176 
1177   // We have to be careful here as these two calculations can overflow
1178   // 32-bit size_t's.
1179   double used_after_gc_d = (double) used_after_gc;
1180   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1181   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1182 
1183   // Let's make sure that they are both under the max heap size, which
1184   // by default will make them fit into a size_t.
1185   double desired_capacity_upper_bound = (double) max_heap_size;
1186   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1187                                     desired_capacity_upper_bound);
1188   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1189                                     desired_capacity_upper_bound);
1190 
1191   // We can now safely turn them into size_t's.
1192   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1193   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1194 
1195   // This assert only makes sense here, before we adjust them
1196   // with respect to the min and max heap size.
1197   assert(minimum_desired_capacity <= maximum_desired_capacity,
1198          "minimum_desired_capacity = " SIZE_FORMAT ", "
1199          "maximum_desired_capacity = " SIZE_FORMAT,
1200          minimum_desired_capacity, maximum_desired_capacity);
1201 
1202   // Should not be greater than the heap max size. No need to adjust
1203   // it with respect to the heap min size as it's a lower bound (i.e.,
1204   // we'll try to make the capacity larger than it, not smaller).
1205   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1206   // Should not be less than the heap min size. No need to adjust it
1207   // with respect to the heap max size as it's an upper bound (i.e.,
1208   // we'll try to make the capacity smaller than it, not greater).
1209   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1210 
1211   if (capacity_after_gc < minimum_desired_capacity) {
1212     // Don't expand unless it's significant
1213     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1214 
1215     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1216                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1217                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1218                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1219 
1220     expand(expand_bytes, _workers);
1221 
1222     // No expansion, now see if we want to shrink
1223   } else if (capacity_after_gc > maximum_desired_capacity) {
1224     // Capacity too large, compute shrinking size
1225     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1226 
1227     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1228                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1229                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1230                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1231 
1232     shrink(shrink_bytes);
1233   }
1234 }
1235 
1236 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1237                                                             bool do_gc,
1238                                                             bool clear_all_soft_refs,
1239                                                             bool expect_null_mutator_alloc_region,
1240                                                             bool* gc_succeeded) {
1241   *gc_succeeded = true;
1242   // Let's attempt the allocation first.
1243   HeapWord* result =
1244     attempt_allocation_at_safepoint(word_size,
1245                                     expect_null_mutator_alloc_region);
1246   if (result != NULL) {
1247     return result;
1248   }
1249 
1250   // In a G1 heap, we're supposed to keep allocation from failing by
1251   // incremental pauses.  Therefore, at least for now, we'll favor
1252   // expansion over collection.  (This might change in the future if we can
1253   // do something smarter than full collection to satisfy a failed alloc.)
1254   result = expand_and_allocate(word_size);
1255   if (result != NULL) {
1256     return result;
1257   }
1258 
1259   if (do_gc) {
1260     // Expansion didn't work, we'll try to do a Full GC.
1261     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1262                                        clear_all_soft_refs);
1263   }
1264 
1265   return NULL;
1266 }
1267 
1268 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1269                                                      bool* succeeded) {
1270   assert_at_safepoint_on_vm_thread();
1271 
1272   // Attempts to allocate followed by Full GC.
1273   HeapWord* result =
1274     satisfy_failed_allocation_helper(word_size,
1275                                      true,  /* do_gc */
1276                                      false, /* clear_all_soft_refs */
1277                                      false, /* expect_null_mutator_alloc_region */
1278                                      succeeded);
1279 
1280   if (result != NULL || !*succeeded) {
1281     return result;
1282   }
1283 
1284   // Attempts to allocate followed by Full GC that will collect all soft references.
1285   result = satisfy_failed_allocation_helper(word_size,
1286                                             true, /* do_gc */
1287                                             true, /* clear_all_soft_refs */
1288                                             true, /* expect_null_mutator_alloc_region */
1289                                             succeeded);
1290 
1291   if (result != NULL || !*succeeded) {
1292     return result;
1293   }
1294 
1295   // Attempts to allocate, no GC
1296   result = satisfy_failed_allocation_helper(word_size,
1297                                             false, /* do_gc */
1298                                             false, /* clear_all_soft_refs */
1299                                             true,  /* expect_null_mutator_alloc_region */
1300                                             succeeded);
1301 
1302   if (result != NULL) {
1303     return result;
1304   }
1305 
1306   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1307          "Flag should have been handled and cleared prior to this point");
1308 
1309   // What else?  We might try synchronous finalization later.  If the total
1310   // space available is large enough for the allocation, then a more
1311   // complete compaction phase than we've tried so far might be
1312   // appropriate.
1313   return NULL;
1314 }
1315 
1316 // Attempting to expand the heap sufficiently
1317 // to support an allocation of the given "word_size".  If
1318 // successful, perform the allocation and return the address of the
1319 // allocated block, or else "NULL".
1320 
1321 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1322   assert_at_safepoint_on_vm_thread();
1323 
1324   _verifier->verify_region_sets_optional();
1325 
1326   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1327   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1328                             word_size * HeapWordSize);
1329 
1330 
1331   if (expand(expand_bytes, _workers)) {
1332     _hrm->verify_optional();
1333     _verifier->verify_region_sets_optional();
1334     return attempt_allocation_at_safepoint(word_size,
1335                                            false /* expect_null_mutator_alloc_region */);
1336   }
1337   return NULL;
1338 }
1339 
1340 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1341   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1342   aligned_expand_bytes = align_up(aligned_expand_bytes,
1343                                        HeapRegion::GrainBytes);
1344 
1345   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1346                             expand_bytes, aligned_expand_bytes);
1347 
1348   if (is_maximal_no_gc()) {
1349     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1350     return false;
1351   }
1352 
1353   double expand_heap_start_time_sec = os::elapsedTime();
1354   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1355   assert(regions_to_expand > 0, "Must expand by at least one region");
1356 
1357   uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1358   if (expand_time_ms != NULL) {
1359     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1360   }
1361 
1362   if (expanded_by > 0) {
1363     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1364     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1365     g1_policy()->record_new_heap_size(num_regions());
1366   } else {
1367     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1368 
1369     // The expansion of the virtual storage space was unsuccessful.
1370     // Let's see if it was because we ran out of swap.
1371     if (G1ExitOnExpansionFailure &&
1372         _hrm->available() >= regions_to_expand) {
1373       // We had head room...
1374       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1375     }
1376   }
1377   return regions_to_expand > 0;
1378 }
1379 
1380 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1381   size_t aligned_shrink_bytes =
1382     ReservedSpace::page_align_size_down(shrink_bytes);
1383   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1384                                          HeapRegion::GrainBytes);
1385   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1386 
1387   uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1388   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1389 
1390 
1391   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",
1392                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1393   if (num_regions_removed > 0) {
1394     g1_policy()->record_new_heap_size(num_regions());
1395   } else {
1396     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1397   }
1398 }
1399 
1400 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1401   _verifier->verify_region_sets_optional();
1402 
1403   // We should only reach here at the end of a Full GC or during Remark which
1404   // means we should not not be holding to any GC alloc regions. The method
1405   // below will make sure of that and do any remaining clean up.
1406   _allocator->abandon_gc_alloc_regions();
1407 
1408   // Instead of tearing down / rebuilding the free lists here, we
1409   // could instead use the remove_all_pending() method on free_list to
1410   // remove only the ones that we need to remove.
1411   tear_down_region_sets(true /* free_list_only */);
1412   shrink_helper(shrink_bytes);
1413   rebuild_region_sets(true /* free_list_only */);
1414 
1415   _hrm->verify_optional();
1416   _verifier->verify_region_sets_optional();
1417 }
1418 
1419 class OldRegionSetChecker : public HeapRegionSetChecker {
1420 public:
1421   void check_mt_safety() {
1422     // Master Old Set MT safety protocol:
1423     // (a) If we're at a safepoint, operations on the master old set
1424     // should be invoked:
1425     // - by the VM thread (which will serialize them), or
1426     // - by the GC workers while holding the FreeList_lock, if we're
1427     //   at a safepoint for an evacuation pause (this lock is taken
1428     //   anyway when an GC alloc region is retired so that a new one
1429     //   is allocated from the free list), or
1430     // - by the GC workers while holding the OldSets_lock, if we're at a
1431     //   safepoint for a cleanup pause.
1432     // (b) If we're not at a safepoint, operations on the master old set
1433     // should be invoked while holding the Heap_lock.
1434 
1435     if (SafepointSynchronize::is_at_safepoint()) {
1436       guarantee(Thread::current()->is_VM_thread() ||
1437                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1438                 "master old set MT safety protocol at a safepoint");
1439     } else {
1440       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1441     }
1442   }
1443   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1444   const char* get_description() { return "Old Regions"; }
1445 };
1446 
1447 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1448 public:
1449   void check_mt_safety() {
1450     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1451               "May only change archive regions during initialization or safepoint.");
1452   }
1453   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1454   const char* get_description() { return "Archive Regions"; }
1455 };
1456 
1457 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1458 public:
1459   void check_mt_safety() {
1460     // Humongous Set MT safety protocol:
1461     // (a) If we're at a safepoint, operations on the master humongous
1462     // set should be invoked by either the VM thread (which will
1463     // serialize them) or by the GC workers while holding the
1464     // OldSets_lock.
1465     // (b) If we're not at a safepoint, operations on the master
1466     // humongous set should be invoked while holding the Heap_lock.
1467 
1468     if (SafepointSynchronize::is_at_safepoint()) {
1469       guarantee(Thread::current()->is_VM_thread() ||
1470                 OldSets_lock->owned_by_self(),
1471                 "master humongous set MT safety protocol at a safepoint");
1472     } else {
1473       guarantee(Heap_lock->owned_by_self(),
1474                 "master humongous set MT safety protocol outside a safepoint");
1475     }
1476   }
1477   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1478   const char* get_description() { return "Humongous Regions"; }
1479 };
1480 
1481 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1482   CollectedHeap(),
1483   _young_gen_sampling_thread(NULL),
1484   _workers(NULL),
1485   _collector_policy(collector_policy),
1486   _card_table(NULL),
1487   _soft_ref_policy(),
1488   _old_set("Old Region Set", new OldRegionSetChecker()),
1489   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1490   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1491   _bot(NULL),
1492   _listener(),
1493   _hrm(NULL),
1494   _allocator(NULL),
1495   _verifier(NULL),
1496   _summary_bytes_used(0),
1497   _archive_allocator(NULL),
1498   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1499   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1500   _expand_heap_after_alloc_failure(true),
1501   _g1mm(NULL),
1502   _humongous_reclaim_candidates(),
1503   _has_humongous_reclaim_candidates(false),
1504   _hr_printer(),
1505   _collector_state(),
1506   _old_marking_cycles_started(0),
1507   _old_marking_cycles_completed(0),
1508   _eden(),
1509   _survivor(),
1510   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1511   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1512   _g1_policy(G1Policy::create_policy(collector_policy, _gc_timer_stw)),
1513   _heap_sizing_policy(NULL),
1514   _collection_set(this, _g1_policy),
1515   _hot_card_cache(NULL),
1516   _g1_rem_set(NULL),
1517   _dirty_card_queue_set(false),
1518   _cm(NULL),
1519   _cm_thread(NULL),
1520   _cr(NULL),
1521   _task_queues(NULL),
1522   _evacuation_failed(false),
1523   _evacuation_failed_info_array(NULL),
1524   _preserved_marks_set(true /* in_c_heap */),
1525 #ifndef PRODUCT
1526   _evacuation_failure_alot_for_current_gc(false),
1527   _evacuation_failure_alot_gc_number(0),
1528   _evacuation_failure_alot_count(0),
1529 #endif
1530   _ref_processor_stw(NULL),
1531   _is_alive_closure_stw(this),
1532   _is_subject_to_discovery_stw(this),
1533   _ref_processor_cm(NULL),
1534   _is_alive_closure_cm(this),
1535   _is_subject_to_discovery_cm(this),
1536   _in_cset_fast_test() {
1537 
1538   _verifier = new G1HeapVerifier(this);
1539 
1540   _allocator = new G1Allocator(this);
1541 
1542   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1543 
1544   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1545 
1546   // Override the default _filler_array_max_size so that no humongous filler
1547   // objects are created.
1548   _filler_array_max_size = _humongous_object_threshold_in_words;
1549 
1550   uint n_queues = ParallelGCThreads;
1551   _task_queues = new RefToScanQueueSet(n_queues);
1552 
1553   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1554 
1555   for (uint i = 0; i < n_queues; i++) {
1556     RefToScanQueue* q = new RefToScanQueue();
1557     q->initialize();
1558     _task_queues->register_queue(i, q);
1559     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1560   }
1561 
1562   // Initialize the G1EvacuationFailureALot counters and flags.
1563   NOT_PRODUCT(reset_evacuation_should_fail();)
1564 
1565   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1566 }
1567 
1568 static size_t actual_reserved_page_size(ReservedSpace rs) {
1569   size_t page_size = os::vm_page_size();
1570   if (UseLargePages) {
1571     // There are two ways to manage large page memory.
1572     // 1. OS supports committing large page memory.
1573     // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1574     //    And ReservedSpace calls it 'special'. If we failed to set 'special',
1575     //    we reserved memory without large page.
1576     if (os::can_commit_large_page_memory() || rs.special()) {
1577       page_size = rs.alignment();
1578     }
1579   }
1580 
1581   return page_size;
1582 }
1583 
1584 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1585                                                                  size_t size,
1586                                                                  size_t translation_factor) {
1587   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1588   // Allocate a new reserved space, preferring to use large pages.
1589   ReservedSpace rs(size, preferred_page_size);
1590   size_t page_size = actual_reserved_page_size(rs);
1591   G1RegionToSpaceMapper* result  =
1592     G1RegionToSpaceMapper::create_mapper(rs,
1593                                          size,
1594                                          page_size,
1595                                          HeapRegion::GrainBytes,
1596                                          translation_factor,
1597                                          mtGC);
1598 
1599   os::trace_page_sizes_for_requested_size(description,
1600                                           size,
1601                                           preferred_page_size,
1602                                           page_size,
1603                                           rs.base(),
1604                                           rs.size());
1605 
1606   return result;
1607 }
1608 
1609 jint G1CollectedHeap::initialize_concurrent_refinement() {
1610   jint ecode = JNI_OK;
1611   _cr = G1ConcurrentRefine::create(&ecode);
1612   return ecode;
1613 }
1614 
1615 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1616   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1617   if (_young_gen_sampling_thread->osthread() == NULL) {
1618     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1619     return JNI_ENOMEM;
1620   }
1621   return JNI_OK;
1622 }
1623 
1624 jint G1CollectedHeap::initialize() {
1625   os::enable_vtime();
1626 
1627   // Necessary to satisfy locking discipline assertions.
1628 
1629   MutexLocker x(Heap_lock);
1630 
1631   // While there are no constraints in the GC code that HeapWordSize
1632   // be any particular value, there are multiple other areas in the
1633   // system which believe this to be true (e.g. oop->object_size in some
1634   // cases incorrectly returns the size in wordSize units rather than
1635   // HeapWordSize).
1636   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1637 
1638   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1639   size_t max_byte_size = g1_collector_policy()->heap_reserved_size_bytes();
1640   size_t heap_alignment = collector_policy()->heap_alignment();
1641 
1642   // Ensure that the sizes are properly aligned.
1643   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1644   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1645   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1646 
1647   // Reserve the maximum.
1648 
1649   // When compressed oops are enabled, the preferred heap base
1650   // is calculated by subtracting the requested size from the
1651   // 32Gb boundary and using the result as the base address for
1652   // heap reservation. If the requested size is not aligned to
1653   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1654   // into the ReservedHeapSpace constructor) then the actual
1655   // base of the reserved heap may end up differing from the
1656   // address that was requested (i.e. the preferred heap base).
1657   // If this happens then we could end up using a non-optimal
1658   // compressed oops mode.
1659 
1660   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1661                                                  heap_alignment);
1662 
1663   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1664 
1665   // Create the barrier set for the entire reserved region.
1666   G1CardTable* ct = new G1CardTable(reserved_region());
1667   ct->initialize();
1668   G1BarrierSet* bs = new G1BarrierSet(ct);
1669   bs->initialize();
1670   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1671   BarrierSet::set_barrier_set(bs);
1672   _card_table = ct;
1673 
1674   G1BarrierSet::satb_mark_queue_set().initialize(this,
1675                                                  SATB_Q_CBL_mon,
1676                                                  &bs->satb_mark_queue_buffer_allocator(),
1677                                                  G1SATBProcessCompletedThreshold,
1678                                                  G1SATBBufferEnqueueingThresholdPercent,
1679                                                  Shared_SATB_Q_lock);
1680 
1681   // process_completed_buffers_threshold and max_completed_buffers are updated
1682   // later, based on the concurrent refinement object.
1683   G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1684                                                   &bs->dirty_card_queue_buffer_allocator(),
1685                                                   Shared_DirtyCardQ_lock,
1686                                                   true); // init_free_ids
1687 
1688   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1689                                     &bs->dirty_card_queue_buffer_allocator(),
1690                                     Shared_DirtyCardQ_lock);
1691 
1692   // Create the hot card cache.
1693   _hot_card_cache = new G1HotCardCache(this);
1694 
1695   // Carve out the G1 part of the heap.
1696   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1697   size_t page_size = actual_reserved_page_size(heap_rs);
1698   G1RegionToSpaceMapper* heap_storage =
1699     G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1700                                               g1_rs.size(),
1701                                               page_size,
1702                                               HeapRegion::GrainBytes,
1703                                               1,
1704                                               mtJavaHeap);
1705   if(heap_storage == NULL) {
1706     vm_shutdown_during_initialization("Could not initialize G1 heap");
1707     return JNI_ERR;
1708   }
1709 
1710   os::trace_page_sizes("Heap",
1711                        collector_policy()->min_heap_byte_size(),
1712                        max_byte_size,
1713                        page_size,
1714                        heap_rs.base(),
1715                        heap_rs.size());
1716   heap_storage->set_mapping_changed_listener(&_listener);
1717 
1718   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1719   G1RegionToSpaceMapper* bot_storage =
1720     create_aux_memory_mapper("Block Offset Table",
1721                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1722                              G1BlockOffsetTable::heap_map_factor());
1723 
1724   G1RegionToSpaceMapper* cardtable_storage =
1725     create_aux_memory_mapper("Card Table",
1726                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1727                              G1CardTable::heap_map_factor());
1728 
1729   G1RegionToSpaceMapper* card_counts_storage =
1730     create_aux_memory_mapper("Card Counts Table",
1731                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1732                              G1CardCounts::heap_map_factor());
1733 
1734   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1735   G1RegionToSpaceMapper* prev_bitmap_storage =
1736     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1737   G1RegionToSpaceMapper* next_bitmap_storage =
1738     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1739 
1740   _hrm = HeapRegionManager::create_manager(this, g1_collector_policy());
1741 
1742   _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1743   _card_table->initialize(cardtable_storage);
1744   // Do later initialization work for concurrent refinement.
1745   _hot_card_cache->initialize(card_counts_storage);
1746 
1747   // 6843694 - ensure that the maximum region index can fit
1748   // in the remembered set structures.
1749   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1750   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1751 
1752   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1753   // start within the first card.
1754   guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1755   // Also create a G1 rem set.
1756   _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1757   _g1_rem_set->initialize(max_reserved_capacity(), max_regions());
1758 
1759   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1760   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1761   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1762             "too many cards per region");
1763 
1764   FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1765 
1766   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1767 
1768   {
1769     HeapWord* start = _hrm->reserved().start();
1770     HeapWord* end = _hrm->reserved().end();
1771     size_t granularity = HeapRegion::GrainBytes;
1772 
1773     _in_cset_fast_test.initialize(start, end, granularity);
1774     _humongous_reclaim_candidates.initialize(start, end, granularity);
1775   }
1776 
1777   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1778                           true /* are_GC_task_threads */,
1779                           false /* are_ConcurrentGC_threads */);
1780   if (_workers == NULL) {
1781     return JNI_ENOMEM;
1782   }
1783   _workers->initialize_workers();
1784 
1785   // Create the G1ConcurrentMark data structure and thread.
1786   // (Must do this late, so that "max_regions" is defined.)
1787   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1788   if (_cm == NULL || !_cm->completed_initialization()) {
1789     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1790     return JNI_ENOMEM;
1791   }
1792   _cm_thread = _cm->cm_thread();
1793 
1794   // Now expand into the initial heap size.
1795   if (!expand(init_byte_size, _workers)) {
1796     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1797     return JNI_ENOMEM;
1798   }
1799 
1800   // Perform any initialization actions delegated to the policy.
1801   g1_policy()->init(this, &_collection_set);
1802 
1803   jint ecode = initialize_concurrent_refinement();
1804   if (ecode != JNI_OK) {
1805     return ecode;
1806   }
1807 
1808   ecode = initialize_young_gen_sampling_thread();
1809   if (ecode != JNI_OK) {
1810     return ecode;
1811   }
1812 
1813   {
1814     DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1815     dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone());
1816     dcqs.set_max_completed_buffers(concurrent_refine()->red_zone());
1817   }
1818 
1819   // Here we allocate the dummy HeapRegion that is required by the
1820   // G1AllocRegion class.
1821   HeapRegion* dummy_region = _hrm->get_dummy_region();
1822 
1823   // We'll re-use the same region whether the alloc region will
1824   // require BOT updates or not and, if it doesn't, then a non-young
1825   // region will complain that it cannot support allocations without
1826   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1827   dummy_region->set_eden();
1828   // Make sure it's full.
1829   dummy_region->set_top(dummy_region->end());
1830   G1AllocRegion::setup(this, dummy_region);
1831 
1832   _allocator->init_mutator_alloc_region();
1833 
1834   // Do create of the monitoring and management support so that
1835   // values in the heap have been properly initialized.
1836   _g1mm = new G1MonitoringSupport(this);
1837 
1838   G1StringDedup::initialize();
1839 
1840   _preserved_marks_set.init(ParallelGCThreads);
1841 
1842   _collection_set.initialize(max_regions());
1843 
1844   return JNI_OK;
1845 }
1846 
1847 void G1CollectedHeap::stop() {
1848   // Stop all concurrent threads. We do this to make sure these threads
1849   // do not continue to execute and access resources (e.g. logging)
1850   // that are destroyed during shutdown.
1851   _cr->stop();
1852   _young_gen_sampling_thread->stop();
1853   _cm_thread->stop();
1854   if (G1StringDedup::is_enabled()) {
1855     G1StringDedup::stop();
1856   }
1857 }
1858 
1859 void G1CollectedHeap::safepoint_synchronize_begin() {
1860   SuspendibleThreadSet::synchronize();
1861 }
1862 
1863 void G1CollectedHeap::safepoint_synchronize_end() {
1864   SuspendibleThreadSet::desynchronize();
1865 }
1866 
1867 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1868   return HeapRegion::max_region_size();
1869 }
1870 
1871 void G1CollectedHeap::post_initialize() {
1872   CollectedHeap::post_initialize();
1873   ref_processing_init();
1874 }
1875 
1876 void G1CollectedHeap::ref_processing_init() {
1877   // Reference processing in G1 currently works as follows:
1878   //
1879   // * There are two reference processor instances. One is
1880   //   used to record and process discovered references
1881   //   during concurrent marking; the other is used to
1882   //   record and process references during STW pauses
1883   //   (both full and incremental).
1884   // * Both ref processors need to 'span' the entire heap as
1885   //   the regions in the collection set may be dotted around.
1886   //
1887   // * For the concurrent marking ref processor:
1888   //   * Reference discovery is enabled at initial marking.
1889   //   * Reference discovery is disabled and the discovered
1890   //     references processed etc during remarking.
1891   //   * Reference discovery is MT (see below).
1892   //   * Reference discovery requires a barrier (see below).
1893   //   * Reference processing may or may not be MT
1894   //     (depending on the value of ParallelRefProcEnabled
1895   //     and ParallelGCThreads).
1896   //   * A full GC disables reference discovery by the CM
1897   //     ref processor and abandons any entries on it's
1898   //     discovered lists.
1899   //
1900   // * For the STW processor:
1901   //   * Non MT discovery is enabled at the start of a full GC.
1902   //   * Processing and enqueueing during a full GC is non-MT.
1903   //   * During a full GC, references are processed after marking.
1904   //
1905   //   * Discovery (may or may not be MT) is enabled at the start
1906   //     of an incremental evacuation pause.
1907   //   * References are processed near the end of a STW evacuation pause.
1908   //   * For both types of GC:
1909   //     * Discovery is atomic - i.e. not concurrent.
1910   //     * Reference discovery will not need a barrier.
1911 
1912   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1913 
1914   // Concurrent Mark ref processor
1915   _ref_processor_cm =
1916     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1917                            mt_processing,                                  // mt processing
1918                            ParallelGCThreads,                              // degree of mt processing
1919                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1920                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1921                            false,                                          // Reference discovery is not atomic
1922                            &_is_alive_closure_cm,                          // is alive closure
1923                            true);                                          // allow changes to number of processing threads
1924 
1925   // STW ref processor
1926   _ref_processor_stw =
1927     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1928                            mt_processing,                        // mt processing
1929                            ParallelGCThreads,                    // degree of mt processing
1930                            (ParallelGCThreads > 1),              // mt discovery
1931                            ParallelGCThreads,                    // degree of mt discovery
1932                            true,                                 // Reference discovery is atomic
1933                            &_is_alive_closure_stw,               // is alive closure
1934                            true);                                // allow changes to number of processing threads
1935 }
1936 
1937 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1938   return _collector_policy;
1939 }
1940 
1941 G1CollectorPolicy* G1CollectedHeap::g1_collector_policy() const {
1942   return _collector_policy;
1943 }
1944 
1945 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1946   return &_soft_ref_policy;
1947 }
1948 
1949 size_t G1CollectedHeap::capacity() const {
1950   return _hrm->length() * HeapRegion::GrainBytes;
1951 }
1952 
1953 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1954   return _hrm->total_free_bytes();
1955 }
1956 
1957 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1958   _hot_card_cache->drain(cl, worker_i);
1959 }
1960 
1961 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1962   DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1963   size_t n_completed_buffers = 0;
1964   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1965     n_completed_buffers++;
1966   }
1967   assert(dcqs.completed_buffers_num() == 0, "Completed buffers exist!");
1968   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1969 }
1970 
1971 // Computes the sum of the storage used by the various regions.
1972 size_t G1CollectedHeap::used() const {
1973   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1974   if (_archive_allocator != NULL) {
1975     result += _archive_allocator->used();
1976   }
1977   return result;
1978 }
1979 
1980 size_t G1CollectedHeap::used_unlocked() const {
1981   return _summary_bytes_used;
1982 }
1983 
1984 class SumUsedClosure: public HeapRegionClosure {
1985   size_t _used;
1986 public:
1987   SumUsedClosure() : _used(0) {}
1988   bool do_heap_region(HeapRegion* r) {
1989     _used += r->used();
1990     return false;
1991   }
1992   size_t result() { return _used; }
1993 };
1994 
1995 size_t G1CollectedHeap::recalculate_used() const {
1996   SumUsedClosure blk;
1997   heap_region_iterate(&blk);
1998   return blk.result();
1999 }
2000 
2001 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2002   switch (cause) {
2003     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2004     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2005     case GCCause::_wb_conc_mark:                        return true;
2006     default :                                           return false;
2007   }
2008 }
2009 
2010 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2011   switch (cause) {
2012     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2013     case GCCause::_g1_humongous_allocation: return true;
2014     case GCCause::_g1_periodic_collection:  return G1PeriodicGCInvokesConcurrent;
2015     default:                                return is_user_requested_concurrent_full_gc(cause);
2016   }
2017 }
2018 
2019 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2020   if(g1_policy()->force_upgrade_to_full()) {
2021     return true;
2022   } else if (should_do_concurrent_full_gc(_gc_cause)) {
2023     return false;
2024   } else if (has_regions_left_for_allocation()) {
2025     return false;
2026   } else {
2027     return true;
2028   }
2029 }
2030 
2031 #ifndef PRODUCT
2032 void G1CollectedHeap::allocate_dummy_regions() {
2033   // Let's fill up most of the region
2034   size_t word_size = HeapRegion::GrainWords - 1024;
2035   // And as a result the region we'll allocate will be humongous.
2036   guarantee(is_humongous(word_size), "sanity");
2037 
2038   // _filler_array_max_size is set to humongous object threshold
2039   // but temporarily change it to use CollectedHeap::fill_with_object().
2040   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2041 
2042   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2043     // Let's use the existing mechanism for the allocation
2044     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2045     if (dummy_obj != NULL) {
2046       MemRegion mr(dummy_obj, word_size);
2047       CollectedHeap::fill_with_object(mr);
2048     } else {
2049       // If we can't allocate once, we probably cannot allocate
2050       // again. Let's get out of the loop.
2051       break;
2052     }
2053   }
2054 }
2055 #endif // !PRODUCT
2056 
2057 void G1CollectedHeap::increment_old_marking_cycles_started() {
2058   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2059          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2060          "Wrong marking cycle count (started: %d, completed: %d)",
2061          _old_marking_cycles_started, _old_marking_cycles_completed);
2062 
2063   _old_marking_cycles_started++;
2064 }
2065 
2066 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2067   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2068 
2069   // We assume that if concurrent == true, then the caller is a
2070   // concurrent thread that was joined the Suspendible Thread
2071   // Set. If there's ever a cheap way to check this, we should add an
2072   // assert here.
2073 
2074   // Given that this method is called at the end of a Full GC or of a
2075   // concurrent cycle, and those can be nested (i.e., a Full GC can
2076   // interrupt a concurrent cycle), the number of full collections
2077   // completed should be either one (in the case where there was no
2078   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2079   // behind the number of full collections started.
2080 
2081   // This is the case for the inner caller, i.e. a Full GC.
2082   assert(concurrent ||
2083          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2084          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2085          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2086          "is inconsistent with _old_marking_cycles_completed = %u",
2087          _old_marking_cycles_started, _old_marking_cycles_completed);
2088 
2089   // This is the case for the outer caller, i.e. the concurrent cycle.
2090   assert(!concurrent ||
2091          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2092          "for outer caller (concurrent cycle): "
2093          "_old_marking_cycles_started = %u "
2094          "is inconsistent with _old_marking_cycles_completed = %u",
2095          _old_marking_cycles_started, _old_marking_cycles_completed);
2096 
2097   _old_marking_cycles_completed += 1;
2098 
2099   // We need to clear the "in_progress" flag in the CM thread before
2100   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2101   // is set) so that if a waiter requests another System.gc() it doesn't
2102   // incorrectly see that a marking cycle is still in progress.
2103   if (concurrent) {
2104     _cm_thread->set_idle();
2105   }
2106 
2107   // This notify_all() will ensure that a thread that called
2108   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2109   // and it's waiting for a full GC to finish will be woken up. It is
2110   // waiting in VM_G1CollectForAllocation::doit_epilogue().
2111   FullGCCount_lock->notify_all();
2112 }
2113 
2114 void G1CollectedHeap::collect(GCCause::Cause cause) {
2115   assert_heap_not_locked();
2116 
2117   uint gc_count_before;
2118   uint old_marking_count_before;
2119   uint full_gc_count_before;
2120   bool retry_gc;
2121 
2122   do {
2123     retry_gc = false;
2124 
2125     {
2126       MutexLocker ml(Heap_lock);
2127 
2128       // Read the GC count while holding the Heap_lock
2129       gc_count_before = total_collections();
2130       full_gc_count_before = total_full_collections();
2131       old_marking_count_before = _old_marking_cycles_started;
2132     }
2133 
2134     if (should_do_concurrent_full_gc(cause)) {
2135       // Schedule an initial-mark evacuation pause that will start a
2136       // concurrent cycle. We're setting word_size to 0 which means that
2137       // we are not requesting a post-GC allocation.
2138       VM_G1CollectForAllocation op(0,     /* word_size */
2139                                    gc_count_before,
2140                                    cause,
2141                                    true,  /* should_initiate_conc_mark */
2142                                    g1_policy()->max_pause_time_ms());
2143       VMThread::execute(&op);
2144       if (!op.pause_succeeded()) {
2145         if (old_marking_count_before == _old_marking_cycles_started) {
2146           retry_gc = op.should_retry_gc();
2147         } else {
2148           // A Full GC happened while we were trying to schedule the
2149           // initial-mark GC. No point in starting a new cycle given
2150           // that the whole heap was collected anyway.
2151         }
2152 
2153         if (retry_gc) {
2154           if (GCLocker::is_active_and_needs_gc()) {
2155             GCLocker::stall_until_clear();
2156           }
2157         }
2158       }
2159     } else {
2160       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2161           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2162 
2163         // Schedule a standard evacuation pause. We're setting word_size
2164         // to 0 which means that we are not requesting a post-GC allocation.
2165         VM_G1CollectForAllocation op(0,     /* word_size */
2166                                      gc_count_before,
2167                                      cause,
2168                                      false, /* should_initiate_conc_mark */
2169                                      g1_policy()->max_pause_time_ms());
2170         VMThread::execute(&op);
2171       } else {
2172         // Schedule a Full GC.
2173         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2174         VMThread::execute(&op);
2175       }
2176     }
2177   } while (retry_gc);
2178 }
2179 
2180 bool G1CollectedHeap::is_in(const void* p) const {
2181   if (_hrm->reserved().contains(p)) {
2182     // Given that we know that p is in the reserved space,
2183     // heap_region_containing() should successfully
2184     // return the containing region.
2185     HeapRegion* hr = heap_region_containing(p);
2186     return hr->is_in(p);
2187   } else {
2188     return false;
2189   }
2190 }
2191 
2192 #ifdef ASSERT
2193 bool G1CollectedHeap::is_in_exact(const void* p) const {
2194   bool contains = reserved_region().contains(p);
2195   bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2196   if (contains && available) {
2197     return true;
2198   } else {
2199     return false;
2200   }
2201 }
2202 #endif
2203 
2204 // Iteration functions.
2205 
2206 // Iterates an ObjectClosure over all objects within a HeapRegion.
2207 
2208 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2209   ObjectClosure* _cl;
2210 public:
2211   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2212   bool do_heap_region(HeapRegion* r) {
2213     if (!r->is_continues_humongous()) {
2214       r->object_iterate(_cl);
2215     }
2216     return false;
2217   }
2218 };
2219 
2220 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2221   IterateObjectClosureRegionClosure blk(cl);
2222   heap_region_iterate(&blk);
2223 }
2224 
2225 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2226   _hrm->iterate(cl);
2227 }
2228 
2229 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2230                                                                  HeapRegionClaimer *hrclaimer,
2231                                                                  uint worker_id) const {
2232   _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2233 }
2234 
2235 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2236                                                          HeapRegionClaimer *hrclaimer) const {
2237   _hrm->par_iterate(cl, hrclaimer, 0);
2238 }
2239 
2240 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2241   _collection_set.iterate(cl);
2242 }
2243 
2244 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2245   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2246 }
2247 
2248 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2249   HeapRegion* hr = heap_region_containing(addr);
2250   return hr->block_start(addr);
2251 }
2252 
2253 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2254   HeapRegion* hr = heap_region_containing(addr);
2255   return hr->block_size(addr);
2256 }
2257 
2258 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2259   HeapRegion* hr = heap_region_containing(addr);
2260   return hr->block_is_obj(addr);
2261 }
2262 
2263 bool G1CollectedHeap::supports_tlab_allocation() const {
2264   return true;
2265 }
2266 
2267 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2268   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2269 }
2270 
2271 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2272   return _eden.length() * HeapRegion::GrainBytes;
2273 }
2274 
2275 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2276 // must be equal to the humongous object limit.
2277 size_t G1CollectedHeap::max_tlab_size() const {
2278   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2279 }
2280 
2281 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2282   return _allocator->unsafe_max_tlab_alloc();
2283 }
2284 
2285 size_t G1CollectedHeap::max_capacity() const {
2286   return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2287 }
2288 
2289 size_t G1CollectedHeap::max_reserved_capacity() const {
2290   return _hrm->max_length() * HeapRegion::GrainBytes;
2291 }
2292 
2293 jlong G1CollectedHeap::millis_since_last_gc() {
2294   // See the notes in GenCollectedHeap::millis_since_last_gc()
2295   // for more information about the implementation.
2296   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2297     _g1_policy->collection_pause_end_millis();
2298   if (ret_val < 0) {
2299     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2300       ". returning zero instead.", ret_val);
2301     return 0;
2302   }
2303   return ret_val;
2304 }
2305 
2306 void G1CollectedHeap::deduplicate_string(oop str) {
2307   assert(java_lang_String::is_instance(str), "invariant");
2308 
2309   if (G1StringDedup::is_enabled()) {
2310     G1StringDedup::deduplicate(str);
2311   }
2312 }
2313 
2314 void G1CollectedHeap::prepare_for_verify() {
2315   _verifier->prepare_for_verify();
2316 }
2317 
2318 void G1CollectedHeap::verify(VerifyOption vo) {
2319   _verifier->verify(vo);
2320 }
2321 
2322 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2323   return true;
2324 }
2325 
2326 const char* const* G1CollectedHeap::concurrent_phases() const {
2327   return _cm_thread->concurrent_phases();
2328 }
2329 
2330 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2331   return _cm_thread->request_concurrent_phase(phase);
2332 }
2333 
2334 class PrintRegionClosure: public HeapRegionClosure {
2335   outputStream* _st;
2336 public:
2337   PrintRegionClosure(outputStream* st) : _st(st) {}
2338   bool do_heap_region(HeapRegion* r) {
2339     r->print_on(_st);
2340     return false;
2341   }
2342 };
2343 
2344 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2345                                        const HeapRegion* hr,
2346                                        const VerifyOption vo) const {
2347   switch (vo) {
2348   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2349   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2350   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2351   default:                            ShouldNotReachHere();
2352   }
2353   return false; // keep some compilers happy
2354 }
2355 
2356 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2357                                        const VerifyOption vo) const {
2358   switch (vo) {
2359   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2360   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2361   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2362   default:                            ShouldNotReachHere();
2363   }
2364   return false; // keep some compilers happy
2365 }
2366 
2367 void G1CollectedHeap::print_heap_regions() const {
2368   LogTarget(Trace, gc, heap, region) lt;
2369   if (lt.is_enabled()) {
2370     LogStream ls(lt);
2371     print_regions_on(&ls);
2372   }
2373 }
2374 
2375 void G1CollectedHeap::print_on(outputStream* st) const {
2376   st->print(" %-20s", "garbage-first heap");
2377   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2378             capacity()/K, used_unlocked()/K);
2379   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2380             p2i(_hrm->reserved().start()),
2381             p2i(_hrm->reserved().end()));
2382   st->cr();
2383   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2384   uint young_regions = young_regions_count();
2385   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2386             (size_t) young_regions * HeapRegion::GrainBytes / K);
2387   uint survivor_regions = survivor_regions_count();
2388   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2389             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2390   st->cr();
2391   MetaspaceUtils::print_on(st);
2392 }
2393 
2394 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2395   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2396                "HS=humongous(starts), HC=humongous(continues), "
2397                "CS=collection set, F=free, A=archive, "
2398                "TAMS=top-at-mark-start (previous, next)");
2399   PrintRegionClosure blk(st);
2400   heap_region_iterate(&blk);
2401 }
2402 
2403 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2404   print_on(st);
2405 
2406   // Print the per-region information.
2407   print_regions_on(st);
2408 }
2409 
2410 void G1CollectedHeap::print_on_error(outputStream* st) const {
2411   this->CollectedHeap::print_on_error(st);
2412 
2413   if (_cm != NULL) {
2414     st->cr();
2415     _cm->print_on_error(st);
2416   }
2417 }
2418 
2419 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2420   workers()->print_worker_threads_on(st);
2421   _cm_thread->print_on(st);
2422   st->cr();
2423   _cm->print_worker_threads_on(st);
2424   _cr->print_threads_on(st);
2425   _young_gen_sampling_thread->print_on(st);
2426   if (G1StringDedup::is_enabled()) {
2427     G1StringDedup::print_worker_threads_on(st);
2428   }
2429 }
2430 
2431 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2432   workers()->threads_do(tc);
2433   tc->do_thread(_cm_thread);
2434   _cm->threads_do(tc);
2435   _cr->threads_do(tc);
2436   tc->do_thread(_young_gen_sampling_thread);
2437   if (G1StringDedup::is_enabled()) {
2438     G1StringDedup::threads_do(tc);
2439   }
2440 }
2441 
2442 void G1CollectedHeap::print_tracing_info() const {
2443   g1_rem_set()->print_summary_info();
2444   concurrent_mark()->print_summary_info();
2445 }
2446 
2447 #ifndef PRODUCT
2448 // Helpful for debugging RSet issues.
2449 
2450 class PrintRSetsClosure : public HeapRegionClosure {
2451 private:
2452   const char* _msg;
2453   size_t _occupied_sum;
2454 
2455 public:
2456   bool do_heap_region(HeapRegion* r) {
2457     HeapRegionRemSet* hrrs = r->rem_set();
2458     size_t occupied = hrrs->occupied();
2459     _occupied_sum += occupied;
2460 
2461     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2462     if (occupied == 0) {
2463       tty->print_cr("  RSet is empty");
2464     } else {
2465       hrrs->print();
2466     }
2467     tty->print_cr("----------");
2468     return false;
2469   }
2470 
2471   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2472     tty->cr();
2473     tty->print_cr("========================================");
2474     tty->print_cr("%s", msg);
2475     tty->cr();
2476   }
2477 
2478   ~PrintRSetsClosure() {
2479     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2480     tty->print_cr("========================================");
2481     tty->cr();
2482   }
2483 };
2484 
2485 void G1CollectedHeap::print_cset_rsets() {
2486   PrintRSetsClosure cl("Printing CSet RSets");
2487   collection_set_iterate(&cl);
2488 }
2489 
2490 void G1CollectedHeap::print_all_rsets() {
2491   PrintRSetsClosure cl("Printing All RSets");;
2492   heap_region_iterate(&cl);
2493 }
2494 #endif // PRODUCT
2495 
2496 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2497 
2498   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2499   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2500   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2501 
2502   size_t eden_capacity_bytes =
2503     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2504 
2505   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2506   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2507                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2508 }
2509 
2510 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2511   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2512                        stats->unused(), stats->used(), stats->region_end_waste(),
2513                        stats->regions_filled(), stats->direct_allocated(),
2514                        stats->failure_used(), stats->failure_waste());
2515 }
2516 
2517 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2518   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2519   gc_tracer->report_gc_heap_summary(when, heap_summary);
2520 
2521   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2522   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2523 }
2524 
2525 G1CollectedHeap* G1CollectedHeap::heap() {
2526   CollectedHeap* heap = Universe::heap();
2527   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2528   assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2529   return (G1CollectedHeap*)heap;
2530 }
2531 
2532 void G1CollectedHeap::gc_prologue(bool full) {
2533   // always_do_update_barrier = false;
2534   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2535 
2536   // This summary needs to be printed before incrementing total collections.
2537   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2538 
2539   // Update common counters.
2540   increment_total_collections(full /* full gc */);
2541   if (full) {
2542     increment_old_marking_cycles_started();
2543   }
2544 
2545   // Fill TLAB's and such
2546   double start = os::elapsedTime();
2547   ensure_parsability(true);
2548   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2549 }
2550 
2551 void G1CollectedHeap::gc_epilogue(bool full) {
2552   // Update common counters.
2553   if (full) {
2554     // Update the number of full collections that have been completed.
2555     increment_old_marking_cycles_completed(false /* concurrent */);
2556   }
2557 
2558   // We are at the end of the GC. Total collections has already been increased.
2559   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2560 
2561   // FIXME: what is this about?
2562   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2563   // is set.
2564 #if COMPILER2_OR_JVMCI
2565   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2566 #endif
2567   // always_do_update_barrier = true;
2568 
2569   double start = os::elapsedTime();
2570   resize_all_tlabs();
2571   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2572 
2573   MemoryService::track_memory_usage();
2574   // We have just completed a GC. Update the soft reference
2575   // policy with the new heap occupancy
2576   Universe::update_heap_info_at_gc();
2577 }
2578 
2579 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2580                                                uint gc_count_before,
2581                                                bool* succeeded,
2582                                                GCCause::Cause gc_cause) {
2583   assert_heap_not_locked_and_not_at_safepoint();
2584   VM_G1CollectForAllocation op(word_size,
2585                                gc_count_before,
2586                                gc_cause,
2587                                false, /* should_initiate_conc_mark */
2588                                g1_policy()->max_pause_time_ms());
2589   VMThread::execute(&op);
2590 
2591   HeapWord* result = op.result();
2592   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2593   assert(result == NULL || ret_succeeded,
2594          "the result should be NULL if the VM did not succeed");
2595   *succeeded = ret_succeeded;
2596 
2597   assert_heap_not_locked();
2598   return result;
2599 }
2600 
2601 void G1CollectedHeap::do_concurrent_mark() {
2602   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2603   if (!_cm_thread->in_progress()) {
2604     _cm_thread->set_started();
2605     CGC_lock->notify();
2606   }
2607 }
2608 
2609 size_t G1CollectedHeap::pending_card_num() {
2610   size_t extra_cards = 0;
2611   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2612     DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2613     extra_cards += dcq.size();
2614   }
2615   DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2616   size_t buffer_size = dcqs.buffer_size();
2617   size_t buffer_num = dcqs.completed_buffers_num();
2618 
2619   return buffer_size * buffer_num + extra_cards;
2620 }
2621 
2622 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2623   // We don't nominate objects with many remembered set entries, on
2624   // the assumption that such objects are likely still live.
2625   HeapRegionRemSet* rem_set = r->rem_set();
2626 
2627   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2628          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2629          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2630 }
2631 
2632 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2633  private:
2634   size_t _total_humongous;
2635   size_t _candidate_humongous;
2636 
2637   DirtyCardQueue _dcq;
2638 
2639   bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2640     assert(region->is_starts_humongous(), "Must start a humongous object");
2641 
2642     oop obj = oop(region->bottom());
2643 
2644     // Dead objects cannot be eager reclaim candidates. Due to class
2645     // unloading it is unsafe to query their classes so we return early.
2646     if (g1h->is_obj_dead(obj, region)) {
2647       return false;
2648     }
2649 
2650     // If we do not have a complete remembered set for the region, then we can
2651     // not be sure that we have all references to it.
2652     if (!region->rem_set()->is_complete()) {
2653       return false;
2654     }
2655     // Candidate selection must satisfy the following constraints
2656     // while concurrent marking is in progress:
2657     //
2658     // * In order to maintain SATB invariants, an object must not be
2659     // reclaimed if it was allocated before the start of marking and
2660     // has not had its references scanned.  Such an object must have
2661     // its references (including type metadata) scanned to ensure no
2662     // live objects are missed by the marking process.  Objects
2663     // allocated after the start of concurrent marking don't need to
2664     // be scanned.
2665     //
2666     // * An object must not be reclaimed if it is on the concurrent
2667     // mark stack.  Objects allocated after the start of concurrent
2668     // marking are never pushed on the mark stack.
2669     //
2670     // Nominating only objects allocated after the start of concurrent
2671     // marking is sufficient to meet both constraints.  This may miss
2672     // some objects that satisfy the constraints, but the marking data
2673     // structures don't support efficiently performing the needed
2674     // additional tests or scrubbing of the mark stack.
2675     //
2676     // However, we presently only nominate is_typeArray() objects.
2677     // A humongous object containing references induces remembered
2678     // set entries on other regions.  In order to reclaim such an
2679     // object, those remembered sets would need to be cleaned up.
2680     //
2681     // We also treat is_typeArray() objects specially, allowing them
2682     // to be reclaimed even if allocated before the start of
2683     // concurrent mark.  For this we rely on mark stack insertion to
2684     // exclude is_typeArray() objects, preventing reclaiming an object
2685     // that is in the mark stack.  We also rely on the metadata for
2686     // such objects to be built-in and so ensured to be kept live.
2687     // Frequent allocation and drop of large binary blobs is an
2688     // important use case for eager reclaim, and this special handling
2689     // may reduce needed headroom.
2690 
2691     return obj->is_typeArray() &&
2692            g1h->is_potential_eager_reclaim_candidate(region);
2693   }
2694 
2695  public:
2696   RegisterHumongousWithInCSetFastTestClosure()
2697   : _total_humongous(0),
2698     _candidate_humongous(0),
2699     _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2700   }
2701 
2702   virtual bool do_heap_region(HeapRegion* r) {
2703     if (!r->is_starts_humongous()) {
2704       return false;
2705     }
2706     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2707 
2708     bool is_candidate = humongous_region_is_candidate(g1h, r);
2709     uint rindex = r->hrm_index();
2710     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2711     if (is_candidate) {
2712       _candidate_humongous++;
2713       g1h->register_humongous_region_with_cset(rindex);
2714       // Is_candidate already filters out humongous object with large remembered sets.
2715       // If we have a humongous object with a few remembered sets, we simply flush these
2716       // remembered set entries into the DCQS. That will result in automatic
2717       // re-evaluation of their remembered set entries during the following evacuation
2718       // phase.
2719       if (!r->rem_set()->is_empty()) {
2720         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2721                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2722         G1CardTable* ct = g1h->card_table();
2723         HeapRegionRemSetIterator hrrs(r->rem_set());
2724         size_t card_index;
2725         while (hrrs.has_next(card_index)) {
2726           jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2727           // The remembered set might contain references to already freed
2728           // regions. Filter out such entries to avoid failing card table
2729           // verification.
2730           if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2731             if (*card_ptr != G1CardTable::dirty_card_val()) {
2732               *card_ptr = G1CardTable::dirty_card_val();
2733               _dcq.enqueue(card_ptr);
2734             }
2735           }
2736         }
2737         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2738                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2739                hrrs.n_yielded(), r->rem_set()->occupied());
2740         // We should only clear the card based remembered set here as we will not
2741         // implicitly rebuild anything else during eager reclaim. Note that at the moment
2742         // (and probably never) we do not enter this path if there are other kind of
2743         // remembered sets for this region.
2744         r->rem_set()->clear_locked(true /* only_cardset */);
2745         // Clear_locked() above sets the state to Empty. However we want to continue
2746         // collecting remembered set entries for humongous regions that were not
2747         // reclaimed.
2748         r->rem_set()->set_state_complete();
2749       }
2750       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2751     }
2752     _total_humongous++;
2753 
2754     return false;
2755   }
2756 
2757   size_t total_humongous() const { return _total_humongous; }
2758   size_t candidate_humongous() const { return _candidate_humongous; }
2759 
2760   void flush_rem_set_entries() { _dcq.flush(); }
2761 };
2762 
2763 void G1CollectedHeap::register_humongous_regions_with_cset() {
2764   if (!G1EagerReclaimHumongousObjects) {
2765     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2766     return;
2767   }
2768   double time = os::elapsed_counter();
2769 
2770   // Collect reclaim candidate information and register candidates with cset.
2771   RegisterHumongousWithInCSetFastTestClosure cl;
2772   heap_region_iterate(&cl);
2773 
2774   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2775   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2776                                                                   cl.total_humongous(),
2777                                                                   cl.candidate_humongous());
2778   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2779 
2780   // Finally flush all remembered set entries to re-check into the global DCQS.
2781   cl.flush_rem_set_entries();
2782 }
2783 
2784 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2785   public:
2786     bool do_heap_region(HeapRegion* hr) {
2787       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2788         hr->verify_rem_set();
2789       }
2790       return false;
2791     }
2792 };
2793 
2794 uint G1CollectedHeap::num_task_queues() const {
2795   return _task_queues->size();
2796 }
2797 
2798 #if TASKQUEUE_STATS
2799 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2800   st->print_raw_cr("GC Task Stats");
2801   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2802   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2803 }
2804 
2805 void G1CollectedHeap::print_taskqueue_stats() const {
2806   if (!log_is_enabled(Trace, gc, task, stats)) {
2807     return;
2808   }
2809   Log(gc, task, stats) log;
2810   ResourceMark rm;
2811   LogStream ls(log.trace());
2812   outputStream* st = &ls;
2813 
2814   print_taskqueue_stats_hdr(st);
2815 
2816   TaskQueueStats totals;
2817   const uint n = num_task_queues();
2818   for (uint i = 0; i < n; ++i) {
2819     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2820     totals += task_queue(i)->stats;
2821   }
2822   st->print_raw("tot "); totals.print(st); st->cr();
2823 
2824   DEBUG_ONLY(totals.verify());
2825 }
2826 
2827 void G1CollectedHeap::reset_taskqueue_stats() {
2828   const uint n = num_task_queues();
2829   for (uint i = 0; i < n; ++i) {
2830     task_queue(i)->stats.reset();
2831   }
2832 }
2833 #endif // TASKQUEUE_STATS
2834 
2835 void G1CollectedHeap::wait_for_root_region_scanning() {
2836   double scan_wait_start = os::elapsedTime();
2837   // We have to wait until the CM threads finish scanning the
2838   // root regions as it's the only way to ensure that all the
2839   // objects on them have been correctly scanned before we start
2840   // moving them during the GC.
2841   bool waited = _cm->root_regions()->wait_until_scan_finished();
2842   double wait_time_ms = 0.0;
2843   if (waited) {
2844     double scan_wait_end = os::elapsedTime();
2845     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2846   }
2847   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2848 }
2849 
2850 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2851 private:
2852   G1HRPrinter* _hr_printer;
2853 public:
2854   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2855 
2856   virtual bool do_heap_region(HeapRegion* r) {
2857     _hr_printer->cset(r);
2858     return false;
2859   }
2860 };
2861 
2862 void G1CollectedHeap::start_new_collection_set() {
2863   collection_set()->start_incremental_building();
2864 
2865   clear_cset_fast_test();
2866 
2867   guarantee(_eden.length() == 0, "eden should have been cleared");
2868   g1_policy()->transfer_survivors_to_cset(survivor());
2869 }
2870 
2871 bool
2872 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2873   assert_at_safepoint_on_vm_thread();
2874   guarantee(!is_gc_active(), "collection is not reentrant");
2875 
2876   if (GCLocker::check_active_before_gc()) {
2877     return false;
2878   }
2879 
2880   _gc_timer_stw->register_gc_start();
2881 
2882   GCIdMark gc_id_mark;
2883   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2884 
2885   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2886   ResourceMark rm;
2887 
2888   g1_policy()->note_gc_start();
2889 
2890   wait_for_root_region_scanning();
2891 
2892   print_heap_before_gc();
2893   print_heap_regions();
2894   trace_heap_before_gc(_gc_tracer_stw);
2895 
2896   _verifier->verify_region_sets_optional();
2897   _verifier->verify_dirty_young_regions();
2898 
2899   // We should not be doing initial mark unless the conc mark thread is running
2900   if (!_cm_thread->should_terminate()) {
2901     // This call will decide whether this pause is an initial-mark
2902     // pause. If it is, in_initial_mark_gc() will return true
2903     // for the duration of this pause.
2904     g1_policy()->decide_on_conc_mark_initiation();
2905   }
2906 
2907   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2908   assert(!collector_state()->in_initial_mark_gc() ||
2909           collector_state()->in_young_only_phase(), "sanity");
2910 
2911   // We also do not allow mixed GCs during marking.
2912   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2913 
2914   // Record whether this pause is an initial mark. When the current
2915   // thread has completed its logging output and it's safe to signal
2916   // the CM thread, the flag's value in the policy has been reset.
2917   bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2918 
2919   // Inner scope for scope based logging, timers, and stats collection
2920   {
2921     G1EvacuationInfo evacuation_info;
2922 
2923     if (collector_state()->in_initial_mark_gc()) {
2924       // We are about to start a marking cycle, so we increment the
2925       // full collection counter.
2926       increment_old_marking_cycles_started();
2927       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2928     }
2929 
2930     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2931 
2932     GCTraceCPUTime tcpu;
2933 
2934     G1HeapVerifier::G1VerifyType verify_type;
2935     FormatBuffer<> gc_string("Pause Young ");
2936     if (collector_state()->in_initial_mark_gc()) {
2937       gc_string.append("(Concurrent Start)");
2938       verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2939     } else if (collector_state()->in_young_only_phase()) {
2940       if (collector_state()->in_young_gc_before_mixed()) {
2941         gc_string.append("(Prepare Mixed)");
2942       } else {
2943         gc_string.append("(Normal)");
2944       }
2945       verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2946     } else {
2947       gc_string.append("(Mixed)");
2948       verify_type = G1HeapVerifier::G1VerifyMixed;
2949     }
2950     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2951 
2952     uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
2953                                                             workers()->active_workers(),
2954                                                             Threads::number_of_non_daemon_threads());
2955     active_workers = workers()->update_active_workers(active_workers);
2956     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2957 
2958     G1MonitoringScope ms(g1mm(),
2959                          false /* full_gc */,
2960                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2961 
2962     G1HeapTransition heap_transition(this);
2963     size_t heap_used_bytes_before_gc = used();
2964 
2965     // Don't dynamically change the number of GC threads this early.  A value of
2966     // 0 is used to indicate serial work.  When parallel work is done,
2967     // it will be set.
2968 
2969     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2970       IsGCActiveMark x;
2971 
2972       gc_prologue(false);
2973 
2974       if (VerifyRememberedSets) {
2975         log_info(gc, verify)("[Verifying RemSets before GC]");
2976         VerifyRegionRemSetClosure v_cl;
2977         heap_region_iterate(&v_cl);
2978       }
2979 
2980       _verifier->verify_before_gc(verify_type);
2981 
2982       _verifier->check_bitmaps("GC Start");
2983 
2984 #if COMPILER2_OR_JVMCI
2985       DerivedPointerTable::clear();
2986 #endif
2987 
2988       // Please see comment in g1CollectedHeap.hpp and
2989       // G1CollectedHeap::ref_processing_init() to see how
2990       // reference processing currently works in G1.
2991 
2992       // Enable discovery in the STW reference processor
2993       _ref_processor_stw->enable_discovery();
2994 
2995       {
2996         // We want to temporarily turn off discovery by the
2997         // CM ref processor, if necessary, and turn it back on
2998         // on again later if we do. Using a scoped
2999         // NoRefDiscovery object will do this.
3000         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3001 
3002         // Forget the current alloc region (we might even choose it to be part
3003         // of the collection set!).
3004         _allocator->release_mutator_alloc_region();
3005 
3006         // This timing is only used by the ergonomics to handle our pause target.
3007         // It is unclear why this should not include the full pause. We will
3008         // investigate this in CR 7178365.
3009         //
3010         // Preserving the old comment here if that helps the investigation:
3011         //
3012         // The elapsed time induced by the start time below deliberately elides
3013         // the possible verification above.
3014         double sample_start_time_sec = os::elapsedTime();
3015 
3016         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3017 
3018         if (collector_state()->in_initial_mark_gc()) {
3019           concurrent_mark()->pre_initial_mark();
3020         }
3021 
3022         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3023 
3024         evacuation_info.set_collectionset_regions(collection_set()->region_length());
3025 
3026         register_humongous_regions_with_cset();
3027 
3028         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3029 
3030         // We call this after finalize_cset() to
3031         // ensure that the CSet has been finalized.
3032         _cm->verify_no_cset_oops();
3033 
3034         if (_hr_printer.is_active()) {
3035           G1PrintCollectionSetClosure cl(&_hr_printer);
3036           _collection_set.iterate(&cl);
3037         }
3038 
3039         // Initialize the GC alloc regions.
3040         _allocator->init_gc_alloc_regions(evacuation_info);
3041 
3042         G1ParScanThreadStateSet per_thread_states(this,
3043                                                   workers()->active_workers(),
3044                                                   collection_set()->young_region_length(),
3045                                                   collection_set()->optional_region_length());
3046         pre_evacuate_collection_set();
3047 
3048         // Actually do the work...
3049         evacuate_collection_set(&per_thread_states);
3050         evacuate_optional_collection_set(&per_thread_states);
3051 
3052         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3053 
3054         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3055         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3056 
3057         eagerly_reclaim_humongous_regions();
3058 
3059         record_obj_copy_mem_stats();
3060         _survivor_evac_stats.adjust_desired_plab_sz();
3061         _old_evac_stats.adjust_desired_plab_sz();
3062 
3063         double start = os::elapsedTime();
3064         start_new_collection_set();
3065         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3066 
3067         if (evacuation_failed()) {
3068           double recalculate_used_start = os::elapsedTime();
3069           set_used(recalculate_used());
3070           g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3071 
3072           if (_archive_allocator != NULL) {
3073             _archive_allocator->clear_used();
3074           }
3075           for (uint i = 0; i < ParallelGCThreads; i++) {
3076             if (_evacuation_failed_info_array[i].has_failed()) {
3077               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3078             }
3079           }
3080         } else {
3081           // The "used" of the the collection set have already been subtracted
3082           // when they were freed.  Add in the bytes evacuated.
3083           increase_used(g1_policy()->bytes_copied_during_gc());
3084         }
3085 
3086         if (collector_state()->in_initial_mark_gc()) {
3087           // We have to do this before we notify the CM threads that
3088           // they can start working to make sure that all the
3089           // appropriate initialization is done on the CM object.
3090           concurrent_mark()->post_initial_mark();
3091           // Note that we don't actually trigger the CM thread at
3092           // this point. We do that later when we're sure that
3093           // the current thread has completed its logging output.
3094         }
3095 
3096         allocate_dummy_regions();
3097 
3098         _allocator->init_mutator_alloc_region();
3099 
3100         {
3101           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3102           if (expand_bytes > 0) {
3103             size_t bytes_before = capacity();
3104             // No need for an ergo logging here,
3105             // expansion_amount() does this when it returns a value > 0.
3106             double expand_ms;
3107             if (!expand(expand_bytes, _workers, &expand_ms)) {
3108               // We failed to expand the heap. Cannot do anything about it.
3109             }
3110             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3111           }
3112         }
3113 
3114         // We redo the verification but now wrt to the new CSet which
3115         // has just got initialized after the previous CSet was freed.
3116         _cm->verify_no_cset_oops();
3117 
3118         // This timing is only used by the ergonomics to handle our pause target.
3119         // It is unclear why this should not include the full pause. We will
3120         // investigate this in CR 7178365.
3121         double sample_end_time_sec = os::elapsedTime();
3122         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3123         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3124         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3125 
3126         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3127         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3128 
3129         if (VerifyRememberedSets) {
3130           log_info(gc, verify)("[Verifying RemSets after GC]");
3131           VerifyRegionRemSetClosure v_cl;
3132           heap_region_iterate(&v_cl);
3133         }
3134 
3135         _verifier->verify_after_gc(verify_type);
3136         _verifier->check_bitmaps("GC End");
3137 
3138         assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3139         _ref_processor_stw->verify_no_references_recorded();
3140 
3141         // CM reference discovery will be re-enabled if necessary.
3142       }
3143 
3144 #ifdef TRACESPINNING
3145       ParallelTaskTerminator::print_termination_counts();
3146 #endif
3147 
3148       gc_epilogue(false);
3149     }
3150 
3151     // Print the remainder of the GC log output.
3152     if (evacuation_failed()) {
3153       log_info(gc)("To-space exhausted");
3154     }
3155 
3156     g1_policy()->print_phases();
3157     heap_transition.print();
3158 
3159     // It is not yet to safe to tell the concurrent mark to
3160     // start as we have some optional output below. We don't want the
3161     // output from the concurrent mark thread interfering with this
3162     // logging output either.
3163 
3164     _hrm->verify_optional();
3165     _verifier->verify_region_sets_optional();
3166 
3167     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3168     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3169 
3170     print_heap_after_gc();
3171     print_heap_regions();
3172     trace_heap_after_gc(_gc_tracer_stw);
3173 
3174     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3175     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3176     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3177     // before any GC notifications are raised.
3178     g1mm()->update_sizes();
3179 
3180     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3181     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3182     _gc_timer_stw->register_gc_end();
3183     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3184   }
3185   // It should now be safe to tell the concurrent mark thread to start
3186   // without its logging output interfering with the logging output
3187   // that came from the pause.
3188 
3189   if (should_start_conc_mark) {
3190     // CAUTION: after the doConcurrentMark() call below,
3191     // the concurrent marking thread(s) could be running
3192     // concurrently with us. Make sure that anything after
3193     // this point does not assume that we are the only GC thread
3194     // running. Note: of course, the actual marking work will
3195     // not start until the safepoint itself is released in
3196     // SuspendibleThreadSet::desynchronize().
3197     do_concurrent_mark();
3198   }
3199 
3200   return true;
3201 }
3202 
3203 void G1CollectedHeap::remove_self_forwarding_pointers() {
3204   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3205   workers()->run_task(&rsfp_task);
3206 }
3207 
3208 void G1CollectedHeap::restore_after_evac_failure() {
3209   double remove_self_forwards_start = os::elapsedTime();
3210 
3211   remove_self_forwarding_pointers();
3212   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3213   _preserved_marks_set.restore(&task_executor);
3214 
3215   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3216 }
3217 
3218 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3219   if (!_evacuation_failed) {
3220     _evacuation_failed = true;
3221   }
3222 
3223   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3224   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3225 }
3226 
3227 bool G1ParEvacuateFollowersClosure::offer_termination() {
3228   EventGCPhaseParallel event;
3229   G1ParScanThreadState* const pss = par_scan_state();
3230   start_term_time();
3231   const bool res = terminator()->offer_termination();
3232   end_term_time();
3233   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3234   return res;
3235 }
3236 
3237 void G1ParEvacuateFollowersClosure::do_void() {
3238   EventGCPhaseParallel event;
3239   G1ParScanThreadState* const pss = par_scan_state();
3240   pss->trim_queue();
3241   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3242   do {
3243     EventGCPhaseParallel event;
3244     pss->steal_and_trim_queue(queues());
3245     event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3246   } while (!offer_termination());
3247 }
3248 
3249 class G1ParTask : public AbstractGangTask {
3250 protected:
3251   G1CollectedHeap*         _g1h;
3252   G1ParScanThreadStateSet* _pss;
3253   RefToScanQueueSet*       _queues;
3254   G1RootProcessor*         _root_processor;
3255   TaskTerminator           _terminator;
3256   uint                     _n_workers;
3257 
3258 public:
3259   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3260     : AbstractGangTask("G1 collection"),
3261       _g1h(g1h),
3262       _pss(per_thread_states),
3263       _queues(task_queues),
3264       _root_processor(root_processor),
3265       _terminator(n_workers, _queues),
3266       _n_workers(n_workers)
3267   {}
3268 
3269   void work(uint worker_id) {
3270     if (worker_id >= _n_workers) return;  // no work needed this round
3271 
3272     double start_sec = os::elapsedTime();
3273     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3274 
3275     {
3276       ResourceMark rm;
3277       HandleMark   hm;
3278 
3279       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3280 
3281       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3282       pss->set_ref_discoverer(rp);
3283 
3284       double start_strong_roots_sec = os::elapsedTime();
3285 
3286       _root_processor->evacuate_roots(pss, worker_id);
3287 
3288       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3289       // treating the nmethods visited to act as roots for concurrent marking.
3290       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3291       // objects copied by the current evacuation.
3292       _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3293 
3294       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3295 
3296       double term_sec = 0.0;
3297       size_t evac_term_attempts = 0;
3298       {
3299         double start = os::elapsedTime();
3300         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, _terminator.terminator(), G1GCPhaseTimes::ObjCopy);
3301         evac.do_void();
3302 
3303         evac_term_attempts = evac.term_attempts();
3304         term_sec = evac.term_time();
3305         double elapsed_sec = os::elapsedTime() - start;
3306 
3307         G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3308         p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3309         p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3310         p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3311       }
3312 
3313       assert(pss->queue_is_empty(), "should be empty");
3314 
3315       if (log_is_enabled(Debug, gc, task, stats)) {
3316         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3317         size_t lab_waste;
3318         size_t lab_undo_waste;
3319         pss->waste(lab_waste, lab_undo_waste);
3320         _g1h->print_termination_stats(worker_id,
3321                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3322                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3323                                       term_sec * 1000.0,                          /* evac term time */
3324                                       evac_term_attempts,                         /* evac term attempts */
3325                                       lab_waste,                                  /* alloc buffer waste */
3326                                       lab_undo_waste                              /* undo waste */
3327                                       );
3328       }
3329 
3330       // Close the inner scope so that the ResourceMark and HandleMark
3331       // destructors are executed here and are included as part of the
3332       // "GC Worker Time".
3333     }
3334     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3335   }
3336 };
3337 
3338 void G1CollectedHeap::print_termination_stats_hdr() {
3339   log_debug(gc, task, stats)("GC Termination Stats");
3340   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3341   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3342   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3343 }
3344 
3345 void G1CollectedHeap::print_termination_stats(uint worker_id,
3346                                               double elapsed_ms,
3347                                               double strong_roots_ms,
3348                                               double term_ms,
3349                                               size_t term_attempts,
3350                                               size_t alloc_buffer_waste,
3351                                               size_t undo_waste) const {
3352   log_debug(gc, task, stats)
3353               ("%3d %9.2f %9.2f %6.2f "
3354                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3355                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3356                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3357                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3358                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3359                alloc_buffer_waste * HeapWordSize / K,
3360                undo_waste * HeapWordSize / K);
3361 }
3362 
3363 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3364                                         bool class_unloading_occurred) {
3365   uint num_workers = workers()->active_workers();
3366   ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3367   workers()->run_task(&unlink_task);
3368 }
3369 
3370 // Clean string dedup data structures.
3371 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3372 // record the durations of the phases. Hence the almost-copy.
3373 class G1StringDedupCleaningTask : public AbstractGangTask {
3374   BoolObjectClosure* _is_alive;
3375   OopClosure* _keep_alive;
3376   G1GCPhaseTimes* _phase_times;
3377 
3378 public:
3379   G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3380                             OopClosure* keep_alive,
3381                             G1GCPhaseTimes* phase_times) :
3382     AbstractGangTask("Partial Cleaning Task"),
3383     _is_alive(is_alive),
3384     _keep_alive(keep_alive),
3385     _phase_times(phase_times)
3386   {
3387     assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3388     StringDedup::gc_prologue(true);
3389   }
3390 
3391   ~G1StringDedupCleaningTask() {
3392     StringDedup::gc_epilogue();
3393   }
3394 
3395   void work(uint worker_id) {
3396     StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3397     {
3398       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3399       StringDedupQueue::unlink_or_oops_do(&cl);
3400     }
3401     {
3402       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3403       StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3404     }
3405   }
3406 };
3407 
3408 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3409                                             OopClosure* keep_alive,
3410                                             G1GCPhaseTimes* phase_times) {
3411   G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3412   workers()->run_task(&cl);
3413 }
3414 
3415 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3416  private:
3417   DirtyCardQueueSet* _queue;
3418   G1CollectedHeap* _g1h;
3419  public:
3420   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3421     _queue(queue), _g1h(g1h) { }
3422 
3423   virtual void work(uint worker_id) {
3424     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3425     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3426 
3427     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3428     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3429 
3430     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3431   }
3432 };
3433 
3434 void G1CollectedHeap::redirty_logged_cards() {
3435   double redirty_logged_cards_start = os::elapsedTime();
3436 
3437   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3438   dirty_card_queue_set().reset_for_par_iteration();
3439   workers()->run_task(&redirty_task);
3440 
3441   DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3442   dcq.merge_bufferlists(&dirty_card_queue_set());
3443   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3444 
3445   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3446 }
3447 
3448 // Weak Reference Processing support
3449 
3450 bool G1STWIsAliveClosure::do_object_b(oop p) {
3451   // An object is reachable if it is outside the collection set,
3452   // or is inside and copied.
3453   return !_g1h->is_in_cset(p) || p->is_forwarded();
3454 }
3455 
3456 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3457   assert(obj != NULL, "must not be NULL");
3458   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3459   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3460   // may falsely indicate that this is not the case here: however the collection set only
3461   // contains old regions when concurrent mark is not running.
3462   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3463 }
3464 
3465 // Non Copying Keep Alive closure
3466 class G1KeepAliveClosure: public OopClosure {
3467   G1CollectedHeap*_g1h;
3468 public:
3469   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3470   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3471   void do_oop(oop* p) {
3472     oop obj = *p;
3473     assert(obj != NULL, "the caller should have filtered out NULL values");
3474 
3475     const InCSetState cset_state =_g1h->in_cset_state(obj);
3476     if (!cset_state.is_in_cset_or_humongous()) {
3477       return;
3478     }
3479     if (cset_state.is_in_cset()) {
3480       assert( obj->is_forwarded(), "invariant" );
3481       *p = obj->forwardee();
3482     } else {
3483       assert(!obj->is_forwarded(), "invariant" );
3484       assert(cset_state.is_humongous(),
3485              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3486      _g1h->set_humongous_is_live(obj);
3487     }
3488   }
3489 };
3490 
3491 // Copying Keep Alive closure - can be called from both
3492 // serial and parallel code as long as different worker
3493 // threads utilize different G1ParScanThreadState instances
3494 // and different queues.
3495 
3496 class G1CopyingKeepAliveClosure: public OopClosure {
3497   G1CollectedHeap*         _g1h;
3498   G1ParScanThreadState*    _par_scan_state;
3499 
3500 public:
3501   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3502                             G1ParScanThreadState* pss):
3503     _g1h(g1h),
3504     _par_scan_state(pss)
3505   {}
3506 
3507   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3508   virtual void do_oop(      oop* p) { do_oop_work(p); }
3509 
3510   template <class T> void do_oop_work(T* p) {
3511     oop obj = RawAccess<>::oop_load(p);
3512 
3513     if (_g1h->is_in_cset_or_humongous(obj)) {
3514       // If the referent object has been forwarded (either copied
3515       // to a new location or to itself in the event of an
3516       // evacuation failure) then we need to update the reference
3517       // field and, if both reference and referent are in the G1
3518       // heap, update the RSet for the referent.
3519       //
3520       // If the referent has not been forwarded then we have to keep
3521       // it alive by policy. Therefore we have copy the referent.
3522       //
3523       // When the queue is drained (after each phase of reference processing)
3524       // the object and it's followers will be copied, the reference field set
3525       // to point to the new location, and the RSet updated.
3526       _par_scan_state->push_on_queue(p);
3527     }
3528   }
3529 };
3530 
3531 // Serial drain queue closure. Called as the 'complete_gc'
3532 // closure for each discovered list in some of the
3533 // reference processing phases.
3534 
3535 class G1STWDrainQueueClosure: public VoidClosure {
3536 protected:
3537   G1CollectedHeap* _g1h;
3538   G1ParScanThreadState* _par_scan_state;
3539 
3540   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3541 
3542 public:
3543   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3544     _g1h(g1h),
3545     _par_scan_state(pss)
3546   { }
3547 
3548   void do_void() {
3549     G1ParScanThreadState* const pss = par_scan_state();
3550     pss->trim_queue();
3551   }
3552 };
3553 
3554 // Parallel Reference Processing closures
3555 
3556 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3557 // processing during G1 evacuation pauses.
3558 
3559 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3560 private:
3561   G1CollectedHeap*          _g1h;
3562   G1ParScanThreadStateSet*  _pss;
3563   RefToScanQueueSet*        _queues;
3564   WorkGang*                 _workers;
3565 
3566 public:
3567   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3568                            G1ParScanThreadStateSet* per_thread_states,
3569                            WorkGang* workers,
3570                            RefToScanQueueSet *task_queues) :
3571     _g1h(g1h),
3572     _pss(per_thread_states),
3573     _queues(task_queues),
3574     _workers(workers)
3575   {
3576     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3577   }
3578 
3579   // Executes the given task using concurrent marking worker threads.
3580   virtual void execute(ProcessTask& task, uint ergo_workers);
3581 };
3582 
3583 // Gang task for possibly parallel reference processing
3584 
3585 class G1STWRefProcTaskProxy: public AbstractGangTask {
3586   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3587   ProcessTask&     _proc_task;
3588   G1CollectedHeap* _g1h;
3589   G1ParScanThreadStateSet* _pss;
3590   RefToScanQueueSet* _task_queues;
3591   ParallelTaskTerminator* _terminator;
3592 
3593 public:
3594   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3595                         G1CollectedHeap* g1h,
3596                         G1ParScanThreadStateSet* per_thread_states,
3597                         RefToScanQueueSet *task_queues,
3598                         ParallelTaskTerminator* terminator) :
3599     AbstractGangTask("Process reference objects in parallel"),
3600     _proc_task(proc_task),
3601     _g1h(g1h),
3602     _pss(per_thread_states),
3603     _task_queues(task_queues),
3604     _terminator(terminator)
3605   {}
3606 
3607   virtual void work(uint worker_id) {
3608     // The reference processing task executed by a single worker.
3609     ResourceMark rm;
3610     HandleMark   hm;
3611 
3612     G1STWIsAliveClosure is_alive(_g1h);
3613 
3614     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3615     pss->set_ref_discoverer(NULL);
3616 
3617     // Keep alive closure.
3618     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3619 
3620     // Complete GC closure
3621     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3622 
3623     // Call the reference processing task's work routine.
3624     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3625 
3626     // Note we cannot assert that the refs array is empty here as not all
3627     // of the processing tasks (specifically phase2 - pp2_work) execute
3628     // the complete_gc closure (which ordinarily would drain the queue) so
3629     // the queue may not be empty.
3630   }
3631 };
3632 
3633 // Driver routine for parallel reference processing.
3634 // Creates an instance of the ref processing gang
3635 // task and has the worker threads execute it.
3636 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3637   assert(_workers != NULL, "Need parallel worker threads.");
3638 
3639   assert(_workers->active_workers() >= ergo_workers,
3640          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3641          ergo_workers, _workers->active_workers());
3642   TaskTerminator terminator(ergo_workers, _queues);
3643   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3644 
3645   _workers->run_task(&proc_task_proxy, ergo_workers);
3646 }
3647 
3648 // End of weak reference support closures
3649 
3650 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3651   double ref_proc_start = os::elapsedTime();
3652 
3653   ReferenceProcessor* rp = _ref_processor_stw;
3654   assert(rp->discovery_enabled(), "should have been enabled");
3655 
3656   // Closure to test whether a referent is alive.
3657   G1STWIsAliveClosure is_alive(this);
3658 
3659   // Even when parallel reference processing is enabled, the processing
3660   // of JNI refs is serial and performed serially by the current thread
3661   // rather than by a worker. The following PSS will be used for processing
3662   // JNI refs.
3663 
3664   // Use only a single queue for this PSS.
3665   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3666   pss->set_ref_discoverer(NULL);
3667   assert(pss->queue_is_empty(), "pre-condition");
3668 
3669   // Keep alive closure.
3670   G1CopyingKeepAliveClosure keep_alive(this, pss);
3671 
3672   // Serial Complete GC closure
3673   G1STWDrainQueueClosure drain_queue(this, pss);
3674 
3675   // Setup the soft refs policy...
3676   rp->setup_policy(false);
3677 
3678   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3679 
3680   ReferenceProcessorStats stats;
3681   if (!rp->processing_is_mt()) {
3682     // Serial reference processing...
3683     stats = rp->process_discovered_references(&is_alive,
3684                                               &keep_alive,
3685                                               &drain_queue,
3686                                               NULL,
3687                                               pt);
3688   } else {
3689     uint no_of_gc_workers = workers()->active_workers();
3690 
3691     // Parallel reference processing
3692     assert(no_of_gc_workers <= rp->max_num_queues(),
3693            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3694            no_of_gc_workers,  rp->max_num_queues());
3695 
3696     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3697     stats = rp->process_discovered_references(&is_alive,
3698                                               &keep_alive,
3699                                               &drain_queue,
3700                                               &par_task_executor,
3701                                               pt);
3702   }
3703 
3704   _gc_tracer_stw->report_gc_reference_stats(stats);
3705 
3706   // We have completed copying any necessary live referent objects.
3707   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3708 
3709   make_pending_list_reachable();
3710 
3711   rp->verify_no_references_recorded();
3712 
3713   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3714   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3715 }
3716 
3717 void G1CollectedHeap::make_pending_list_reachable() {
3718   if (collector_state()->in_initial_mark_gc()) {
3719     oop pll_head = Universe::reference_pending_list();
3720     if (pll_head != NULL) {
3721       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3722       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3723     }
3724   }
3725 }
3726 
3727 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3728   double merge_pss_time_start = os::elapsedTime();
3729   per_thread_states->flush();
3730   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3731 }
3732 
3733 void G1CollectedHeap::pre_evacuate_collection_set() {
3734   _expand_heap_after_alloc_failure = true;
3735   _evacuation_failed = false;
3736 
3737   // Disable the hot card cache.
3738   _hot_card_cache->reset_hot_cache_claimed_index();
3739   _hot_card_cache->set_use_cache(false);
3740 
3741   g1_rem_set()->prepare_for_oops_into_collection_set_do();
3742   _preserved_marks_set.assert_empty();
3743 
3744   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3745 
3746   // InitialMark needs claim bits to keep track of the marked-through CLDs.
3747   if (collector_state()->in_initial_mark_gc()) {
3748     double start_clear_claimed_marks = os::elapsedTime();
3749 
3750     ClassLoaderDataGraph::clear_claimed_marks();
3751 
3752     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3753     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3754   }
3755 }
3756 
3757 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3758   // Should G1EvacuationFailureALot be in effect for this GC?
3759   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3760 
3761   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3762 
3763   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3764 
3765   double start_par_time_sec = os::elapsedTime();
3766   double end_par_time_sec;
3767 
3768   {
3769     const uint n_workers = workers()->active_workers();
3770     G1RootProcessor root_processor(this, n_workers);
3771     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3772 
3773     print_termination_stats_hdr();
3774 
3775     workers()->run_task(&g1_par_task);
3776     end_par_time_sec = os::elapsedTime();
3777 
3778     // Closing the inner scope will execute the destructor
3779     // for the G1RootProcessor object. We record the current
3780     // elapsed time before closing the scope so that time
3781     // taken for the destructor is NOT included in the
3782     // reported parallel time.
3783   }
3784 
3785   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3786   phase_times->record_par_time(par_time_ms);
3787 
3788   double code_root_fixup_time_ms =
3789         (os::elapsedTime() - end_par_time_sec) * 1000.0;
3790   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
3791 }
3792 
3793 class G1EvacuateOptionalRegionTask : public AbstractGangTask {
3794   G1CollectedHeap* _g1h;
3795   G1ParScanThreadStateSet* _per_thread_states;
3796   G1OptionalCSet* _optional;
3797   RefToScanQueueSet* _queues;
3798   ParallelTaskTerminator _terminator;
3799 
3800   Tickspan trim_ticks(G1ParScanThreadState* pss) {
3801     Tickspan copy_time = pss->trim_ticks();
3802     pss->reset_trim_ticks();
3803     return copy_time;
3804   }
3805 
3806   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3807     G1EvacuationRootClosures* root_cls = pss->closures();
3808     G1ScanObjsDuringScanRSClosure obj_cl(_g1h, pss);
3809 
3810     size_t scanned = 0;
3811     size_t claimed = 0;
3812     size_t skipped = 0;
3813     size_t used_memory = 0;
3814 
3815     Ticks    start = Ticks::now();
3816     Tickspan copy_time;
3817 
3818     for (uint i = _optional->current_index(); i < _optional->current_limit(); i++) {
3819       HeapRegion* hr = _optional->region_at(i);
3820       G1ScanRSForOptionalClosure scan_opt_cl(&obj_cl);
3821       pss->oops_into_optional_region(hr)->oops_do(&scan_opt_cl, root_cls->raw_strong_oops());
3822       copy_time += trim_ticks(pss);
3823 
3824       G1ScanRSForRegionClosure scan_rs_cl(_g1h->g1_rem_set()->scan_state(), &obj_cl, pss, G1GCPhaseTimes::OptScanRS, worker_id);
3825       scan_rs_cl.do_heap_region(hr);
3826       copy_time += trim_ticks(pss);
3827       scanned += scan_rs_cl.cards_scanned();
3828       claimed += scan_rs_cl.cards_claimed();
3829       skipped += scan_rs_cl.cards_skipped();
3830 
3831       // Chunk lists for this region is no longer needed.
3832       used_memory += pss->oops_into_optional_region(hr)->used_memory();
3833     }
3834 
3835     Tickspan scan_time = (Ticks::now() - start) - copy_time;
3836     G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3837     p->record_or_add_time_secs(G1GCPhaseTimes::OptScanRS, worker_id, scan_time.seconds());
3838     p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, copy_time.seconds());
3839 
3840     p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, scanned, G1GCPhaseTimes::OptCSetScannedCards);
3841     p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, claimed, G1GCPhaseTimes::OptCSetClaimedCards);
3842     p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, skipped, G1GCPhaseTimes::OptCSetSkippedCards);
3843     p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, used_memory, G1GCPhaseTimes::OptCSetUsedMemory);
3844   }
3845 
3846   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3847     Ticks start = Ticks::now();
3848     G1ParEvacuateFollowersClosure cl(_g1h, pss, _queues, &_terminator, G1GCPhaseTimes::OptObjCopy);
3849     cl.do_void();
3850 
3851     Tickspan evac_time = (Ticks::now() - start);
3852     G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3853     p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, evac_time.seconds());
3854     assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming done during optional evacuation");
3855   }
3856 
3857  public:
3858   G1EvacuateOptionalRegionTask(G1CollectedHeap* g1h,
3859                                G1ParScanThreadStateSet* per_thread_states,
3860                                G1OptionalCSet* cset,
3861                                RefToScanQueueSet* queues,
3862                                uint n_workers) :
3863     AbstractGangTask("G1 Evacuation Optional Region Task"),
3864     _g1h(g1h),
3865     _per_thread_states(per_thread_states),
3866     _optional(cset),
3867     _queues(queues),
3868     _terminator(n_workers, _queues) {
3869   }
3870 
3871   void work(uint worker_id) {
3872     ResourceMark rm;
3873     HandleMark  hm;
3874 
3875     G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3876     pss->set_ref_discoverer(_g1h->ref_processor_stw());
3877 
3878     scan_roots(pss, worker_id);
3879     evacuate_live_objects(pss, worker_id);
3880   }
3881 };
3882 
3883 void G1CollectedHeap::evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset) {
3884   class G1MarkScope : public MarkScope {};
3885   G1MarkScope code_mark_scope;
3886 
3887   G1EvacuateOptionalRegionTask task(this, per_thread_states, ocset, _task_queues, workers()->active_workers());
3888   workers()->run_task(&task);
3889 }
3890 
3891 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3892   G1OptionalCSet optional_cset(&_collection_set, per_thread_states);
3893   if (optional_cset.is_empty()) {
3894     return;
3895   }
3896 
3897   if (evacuation_failed()) {
3898     return;
3899   }
3900 
3901   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3902   const double gc_start_time_ms = phase_times->cur_collection_start_sec() * 1000.0;
3903 
3904   double start_time_sec = os::elapsedTime();
3905 
3906   do {
3907     double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3908     double time_left_ms = MaxGCPauseMillis - time_used_ms;
3909 
3910     if (time_left_ms < 0) {
3911       log_trace(gc, ergo, cset)("Skipping %u optional regions, pause time exceeded %.3fms", optional_cset.size(), time_used_ms);
3912       break;
3913     }
3914 
3915     optional_cset.prepare_evacuation(time_left_ms * _g1_policy->optional_evacuation_fraction());
3916     if (optional_cset.prepare_failed()) {
3917       log_trace(gc, ergo, cset)("Skipping %u optional regions, no regions can be evacuated in %.3fms", optional_cset.size(), time_left_ms);
3918       break;
3919     }
3920 
3921     evacuate_optional_regions(per_thread_states, &optional_cset);
3922 
3923     optional_cset.complete_evacuation();
3924     if (optional_cset.evacuation_failed()) {
3925       break;
3926     }
3927   } while (!optional_cset.is_empty());
3928 
3929   phase_times->record_optional_evacuation((os::elapsedTime() - start_time_sec) * 1000.0);
3930 }
3931 
3932 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3933   // Also cleans the card table from temporary duplicate detection information used
3934   // during UpdateRS/ScanRS.
3935   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
3936 
3937   // Process any discovered reference objects - we have
3938   // to do this _before_ we retire the GC alloc regions
3939   // as we may have to copy some 'reachable' referent
3940   // objects (and their reachable sub-graphs) that were
3941   // not copied during the pause.
3942   process_discovered_references(per_thread_states);
3943 
3944   G1STWIsAliveClosure is_alive(this);
3945   G1KeepAliveClosure keep_alive(this);
3946 
3947   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3948                               g1_policy()->phase_times()->weak_phase_times());
3949 
3950   if (G1StringDedup::is_enabled()) {
3951     double string_dedup_time_ms = os::elapsedTime();
3952 
3953     string_dedup_cleaning(&is_alive, &keep_alive, g1_policy()->phase_times());
3954 
3955     double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3956     g1_policy()->phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3957   }
3958 
3959   if (evacuation_failed()) {
3960     restore_after_evac_failure();
3961 
3962     // Reset the G1EvacuationFailureALot counters and flags
3963     // Note: the values are reset only when an actual
3964     // evacuation failure occurs.
3965     NOT_PRODUCT(reset_evacuation_should_fail();)
3966   }
3967 
3968   _preserved_marks_set.assert_empty();
3969 
3970   _allocator->release_gc_alloc_regions(evacuation_info);
3971 
3972   merge_per_thread_state_info(per_thread_states);
3973 
3974   // Reset and re-enable the hot card cache.
3975   // Note the counts for the cards in the regions in the
3976   // collection set are reset when the collection set is freed.
3977   _hot_card_cache->reset_hot_cache();
3978   _hot_card_cache->set_use_cache(true);
3979 
3980   purge_code_root_memory();
3981 
3982   redirty_logged_cards();
3983 #if COMPILER2_OR_JVMCI
3984   double start = os::elapsedTime();
3985   DerivedPointerTable::update_pointers();
3986   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3987 #endif
3988   g1_policy()->print_age_table();
3989 }
3990 
3991 void G1CollectedHeap::record_obj_copy_mem_stats() {
3992   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3993 
3994   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3995                                                create_g1_evac_summary(&_old_evac_stats));
3996 }
3997 
3998 void G1CollectedHeap::free_region(HeapRegion* hr,
3999                                   FreeRegionList* free_list,
4000                                   bool skip_remset,
4001                                   bool skip_hot_card_cache,
4002                                   bool locked) {
4003   assert(!hr->is_free(), "the region should not be free");
4004   assert(!hr->is_empty(), "the region should not be empty");
4005   assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4006   assert(free_list != NULL, "pre-condition");
4007 
4008   if (G1VerifyBitmaps) {
4009     MemRegion mr(hr->bottom(), hr->end());
4010     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4011   }
4012 
4013   // Clear the card counts for this region.
4014   // Note: we only need to do this if the region is not young
4015   // (since we don't refine cards in young regions).
4016   if (!skip_hot_card_cache && !hr->is_young()) {
4017     _hot_card_cache->reset_card_counts(hr);
4018   }
4019   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4020   _g1_policy->remset_tracker()->update_at_free(hr);
4021   free_list->add_ordered(hr);
4022 }
4023 
4024 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4025                                             FreeRegionList* free_list) {
4026   assert(hr->is_humongous(), "this is only for humongous regions");
4027   assert(free_list != NULL, "pre-condition");
4028   hr->clear_humongous();
4029   free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4030 }
4031 
4032 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4033                                            const uint humongous_regions_removed) {
4034   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4035     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4036     _old_set.bulk_remove(old_regions_removed);
4037     _humongous_set.bulk_remove(humongous_regions_removed);
4038   }
4039 
4040 }
4041 
4042 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4043   assert(list != NULL, "list can't be null");
4044   if (!list->is_empty()) {
4045     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4046     _hrm->insert_list_into_free_list(list);
4047   }
4048 }
4049 
4050 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4051   decrease_used(bytes);
4052 }
4053 
4054 class G1FreeCollectionSetTask : public AbstractGangTask {
4055 private:
4056 
4057   // Closure applied to all regions in the collection set to do work that needs to
4058   // be done serially in a single thread.
4059   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4060   private:
4061     G1EvacuationInfo* _evacuation_info;
4062     const size_t* _surviving_young_words;
4063 
4064     // Bytes used in successfully evacuated regions before the evacuation.
4065     size_t _before_used_bytes;
4066     // Bytes used in unsucessfully evacuated regions before the evacuation
4067     size_t _after_used_bytes;
4068 
4069     size_t _bytes_allocated_in_old_since_last_gc;
4070 
4071     size_t _failure_used_words;
4072     size_t _failure_waste_words;
4073 
4074     FreeRegionList _local_free_list;
4075   public:
4076     G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4077       HeapRegionClosure(),
4078       _evacuation_info(evacuation_info),
4079       _surviving_young_words(surviving_young_words),
4080       _before_used_bytes(0),
4081       _after_used_bytes(0),
4082       _bytes_allocated_in_old_since_last_gc(0),
4083       _failure_used_words(0),
4084       _failure_waste_words(0),
4085       _local_free_list("Local Region List for CSet Freeing") {
4086     }
4087 
4088     virtual bool do_heap_region(HeapRegion* r) {
4089       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4090 
4091       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4092       g1h->clear_in_cset(r);
4093 
4094       if (r->is_young()) {
4095         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4096                "Young index %d is wrong for region %u of type %s with %u young regions",
4097                r->young_index_in_cset(),
4098                r->hrm_index(),
4099                r->get_type_str(),
4100                g1h->collection_set()->young_region_length());
4101         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4102         r->record_surv_words_in_group(words_survived);
4103       }
4104 
4105       if (!r->evacuation_failed()) {
4106         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4107         _before_used_bytes += r->used();
4108         g1h->free_region(r,
4109                          &_local_free_list,
4110                          true, /* skip_remset */
4111                          true, /* skip_hot_card_cache */
4112                          true  /* locked */);
4113       } else {
4114         r->uninstall_surv_rate_group();
4115         r->set_young_index_in_cset(-1);
4116         r->set_evacuation_failed(false);
4117         // When moving a young gen region to old gen, we "allocate" that whole region
4118         // there. This is in addition to any already evacuated objects. Notify the
4119         // policy about that.
4120         // Old gen regions do not cause an additional allocation: both the objects
4121         // still in the region and the ones already moved are accounted for elsewhere.
4122         if (r->is_young()) {
4123           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4124         }
4125         // The region is now considered to be old.
4126         r->set_old();
4127         // Do some allocation statistics accounting. Regions that failed evacuation
4128         // are always made old, so there is no need to update anything in the young
4129         // gen statistics, but we need to update old gen statistics.
4130         size_t used_words = r->marked_bytes() / HeapWordSize;
4131 
4132         _failure_used_words += used_words;
4133         _failure_waste_words += HeapRegion::GrainWords - used_words;
4134 
4135         g1h->old_set_add(r);
4136         _after_used_bytes += r->used();
4137       }
4138       return false;
4139     }
4140 
4141     void complete_work() {
4142       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4143 
4144       _evacuation_info->set_regions_freed(_local_free_list.length());
4145       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4146 
4147       g1h->prepend_to_freelist(&_local_free_list);
4148       g1h->decrement_summary_bytes(_before_used_bytes);
4149 
4150       G1Policy* policy = g1h->g1_policy();
4151       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4152 
4153       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4154     }
4155   };
4156 
4157   G1CollectionSet* _collection_set;
4158   G1SerialFreeCollectionSetClosure _cl;
4159   const size_t* _surviving_young_words;
4160 
4161   size_t _rs_lengths;
4162 
4163   volatile jint _serial_work_claim;
4164 
4165   struct WorkItem {
4166     uint region_idx;
4167     bool is_young;
4168     bool evacuation_failed;
4169 
4170     WorkItem(HeapRegion* r) {
4171       region_idx = r->hrm_index();
4172       is_young = r->is_young();
4173       evacuation_failed = r->evacuation_failed();
4174     }
4175   };
4176 
4177   volatile size_t _parallel_work_claim;
4178   size_t _num_work_items;
4179   WorkItem* _work_items;
4180 
4181   void do_serial_work() {
4182     // Need to grab the lock to be allowed to modify the old region list.
4183     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4184     _collection_set->iterate(&_cl);
4185   }
4186 
4187   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4188     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4189 
4190     HeapRegion* r = g1h->region_at(region_idx);
4191     assert(!g1h->is_on_master_free_list(r), "sanity");
4192 
4193     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4194 
4195     if (!is_young) {
4196       g1h->_hot_card_cache->reset_card_counts(r);
4197     }
4198 
4199     if (!evacuation_failed) {
4200       r->rem_set()->clear_locked();
4201     }
4202   }
4203 
4204   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4205   private:
4206     size_t _cur_idx;
4207     WorkItem* _work_items;
4208   public:
4209     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4210 
4211     virtual bool do_heap_region(HeapRegion* r) {
4212       _work_items[_cur_idx++] = WorkItem(r);
4213       return false;
4214     }
4215   };
4216 
4217   void prepare_work() {
4218     G1PrepareFreeCollectionSetClosure cl(_work_items);
4219     _collection_set->iterate(&cl);
4220   }
4221 
4222   void complete_work() {
4223     _cl.complete_work();
4224 
4225     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4226     policy->record_max_rs_lengths(_rs_lengths);
4227     policy->cset_regions_freed();
4228   }
4229 public:
4230   G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4231     AbstractGangTask("G1 Free Collection Set"),
4232     _collection_set(collection_set),
4233     _cl(evacuation_info, surviving_young_words),
4234     _surviving_young_words(surviving_young_words),
4235     _rs_lengths(0),
4236     _serial_work_claim(0),
4237     _parallel_work_claim(0),
4238     _num_work_items(collection_set->region_length()),
4239     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4240     prepare_work();
4241   }
4242 
4243   ~G1FreeCollectionSetTask() {
4244     complete_work();
4245     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4246   }
4247 
4248   // Chunk size for work distribution. The chosen value has been determined experimentally
4249   // to be a good tradeoff between overhead and achievable parallelism.
4250   static uint chunk_size() { return 32; }
4251 
4252   virtual void work(uint worker_id) {
4253     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4254 
4255     // Claim serial work.
4256     if (_serial_work_claim == 0) {
4257       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4258       if (value == 0) {
4259         double serial_time = os::elapsedTime();
4260         do_serial_work();
4261         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4262       }
4263     }
4264 
4265     // Start parallel work.
4266     double young_time = 0.0;
4267     bool has_young_time = false;
4268     double non_young_time = 0.0;
4269     bool has_non_young_time = false;
4270 
4271     while (true) {
4272       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4273       size_t cur = end - chunk_size();
4274 
4275       if (cur >= _num_work_items) {
4276         break;
4277       }
4278 
4279       EventGCPhaseParallel event;
4280       double start_time = os::elapsedTime();
4281 
4282       end = MIN2(end, _num_work_items);
4283 
4284       for (; cur < end; cur++) {
4285         bool is_young = _work_items[cur].is_young;
4286 
4287         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4288 
4289         double end_time = os::elapsedTime();
4290         double time_taken = end_time - start_time;
4291         if (is_young) {
4292           young_time += time_taken;
4293           has_young_time = true;
4294           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4295         } else {
4296           non_young_time += time_taken;
4297           has_non_young_time = true;
4298           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4299         }
4300         start_time = end_time;
4301       }
4302     }
4303 
4304     if (has_young_time) {
4305       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4306     }
4307     if (has_non_young_time) {
4308       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4309     }
4310   }
4311 };
4312 
4313 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4314   _eden.clear();
4315 
4316   double free_cset_start_time = os::elapsedTime();
4317 
4318   {
4319     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4320     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4321 
4322     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4323 
4324     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4325                         cl.name(),
4326                         num_workers,
4327                         _collection_set.region_length());
4328     workers()->run_task(&cl, num_workers);
4329   }
4330   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4331 
4332   collection_set->clear();
4333 }
4334 
4335 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4336  private:
4337   FreeRegionList* _free_region_list;
4338   HeapRegionSet* _proxy_set;
4339   uint _humongous_objects_reclaimed;
4340   uint _humongous_regions_reclaimed;
4341   size_t _freed_bytes;
4342  public:
4343 
4344   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4345     _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4346   }
4347 
4348   virtual bool do_heap_region(HeapRegion* r) {
4349     if (!r->is_starts_humongous()) {
4350       return false;
4351     }
4352 
4353     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4354 
4355     oop obj = (oop)r->bottom();
4356     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4357 
4358     // The following checks whether the humongous object is live are sufficient.
4359     // The main additional check (in addition to having a reference from the roots
4360     // or the young gen) is whether the humongous object has a remembered set entry.
4361     //
4362     // A humongous object cannot be live if there is no remembered set for it
4363     // because:
4364     // - there can be no references from within humongous starts regions referencing
4365     // the object because we never allocate other objects into them.
4366     // (I.e. there are no intra-region references that may be missed by the
4367     // remembered set)
4368     // - as soon there is a remembered set entry to the humongous starts region
4369     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4370     // until the end of a concurrent mark.
4371     //
4372     // It is not required to check whether the object has been found dead by marking
4373     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4374     // all objects allocated during that time are considered live.
4375     // SATB marking is even more conservative than the remembered set.
4376     // So if at this point in the collection there is no remembered set entry,
4377     // nobody has a reference to it.
4378     // At the start of collection we flush all refinement logs, and remembered sets
4379     // are completely up-to-date wrt to references to the humongous object.
4380     //
4381     // Other implementation considerations:
4382     // - never consider object arrays at this time because they would pose
4383     // considerable effort for cleaning up the the remembered sets. This is
4384     // required because stale remembered sets might reference locations that
4385     // are currently allocated into.
4386     uint region_idx = r->hrm_index();
4387     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4388         !r->rem_set()->is_empty()) {
4389       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",
4390                                region_idx,
4391                                (size_t)obj->size() * HeapWordSize,
4392                                p2i(r->bottom()),
4393                                r->rem_set()->occupied(),
4394                                r->rem_set()->strong_code_roots_list_length(),
4395                                next_bitmap->is_marked(r->bottom()),
4396                                g1h->is_humongous_reclaim_candidate(region_idx),
4397                                obj->is_typeArray()
4398                               );
4399       return false;
4400     }
4401 
4402     guarantee(obj->is_typeArray(),
4403               "Only eagerly reclaiming type arrays is supported, but the object "
4404               PTR_FORMAT " is not.", p2i(r->bottom()));
4405 
4406     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",
4407                              region_idx,
4408                              (size_t)obj->size() * HeapWordSize,
4409                              p2i(r->bottom()),
4410                              r->rem_set()->occupied(),
4411                              r->rem_set()->strong_code_roots_list_length(),
4412                              next_bitmap->is_marked(r->bottom()),
4413                              g1h->is_humongous_reclaim_candidate(region_idx),
4414                              obj->is_typeArray()
4415                             );
4416 
4417     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4418     cm->humongous_object_eagerly_reclaimed(r);
4419     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4420            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4421            region_idx,
4422            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4423            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4424     _humongous_objects_reclaimed++;
4425     do {
4426       HeapRegion* next = g1h->next_region_in_humongous(r);
4427       _freed_bytes += r->used();
4428       r->set_containing_set(NULL);
4429       _humongous_regions_reclaimed++;
4430       g1h->free_humongous_region(r, _free_region_list);
4431       r = next;
4432     } while (r != NULL);
4433 
4434     return false;
4435   }
4436 
4437   uint humongous_objects_reclaimed() {
4438     return _humongous_objects_reclaimed;
4439   }
4440 
4441   uint humongous_regions_reclaimed() {
4442     return _humongous_regions_reclaimed;
4443   }
4444 
4445   size_t bytes_freed() const {
4446     return _freed_bytes;
4447   }
4448 };
4449 
4450 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4451   assert_at_safepoint_on_vm_thread();
4452 
4453   if (!G1EagerReclaimHumongousObjects ||
4454       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4455     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4456     return;
4457   }
4458 
4459   double start_time = os::elapsedTime();
4460 
4461   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4462 
4463   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4464   heap_region_iterate(&cl);
4465 
4466   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4467 
4468   G1HRPrinter* hrp = hr_printer();
4469   if (hrp->is_active()) {
4470     FreeRegionListIterator iter(&local_cleanup_list);
4471     while (iter.more_available()) {
4472       HeapRegion* hr = iter.get_next();
4473       hrp->cleanup(hr);
4474     }
4475   }
4476 
4477   prepend_to_freelist(&local_cleanup_list);
4478   decrement_summary_bytes(cl.bytes_freed());
4479 
4480   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4481                                                                     cl.humongous_objects_reclaimed());
4482 }
4483 
4484 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4485 public:
4486   virtual bool do_heap_region(HeapRegion* r) {
4487     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4488     G1CollectedHeap::heap()->clear_in_cset(r);
4489     r->set_young_index_in_cset(-1);
4490     return false;
4491   }
4492 };
4493 
4494 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4495   G1AbandonCollectionSetClosure cl;
4496   collection_set->iterate(&cl);
4497 
4498   collection_set->clear();
4499   collection_set->stop_incremental_building();
4500 }
4501 
4502 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4503   return _allocator->is_retained_old_region(hr);
4504 }
4505 
4506 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4507   _eden.add(hr);
4508   _g1_policy->set_region_eden(hr);
4509 }
4510 
4511 #ifdef ASSERT
4512 
4513 class NoYoungRegionsClosure: public HeapRegionClosure {
4514 private:
4515   bool _success;
4516 public:
4517   NoYoungRegionsClosure() : _success(true) { }
4518   bool do_heap_region(HeapRegion* r) {
4519     if (r->is_young()) {
4520       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4521                             p2i(r->bottom()), p2i(r->end()));
4522       _success = false;
4523     }
4524     return false;
4525   }
4526   bool success() { return _success; }
4527 };
4528 
4529 bool G1CollectedHeap::check_young_list_empty() {
4530   bool ret = (young_regions_count() == 0);
4531 
4532   NoYoungRegionsClosure closure;
4533   heap_region_iterate(&closure);
4534   ret = ret && closure.success();
4535 
4536   return ret;
4537 }
4538 
4539 #endif // ASSERT
4540 
4541 class TearDownRegionSetsClosure : public HeapRegionClosure {
4542   HeapRegionSet *_old_set;
4543 
4544 public:
4545   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4546 
4547   bool do_heap_region(HeapRegion* r) {
4548     if (r->is_old()) {
4549       _old_set->remove(r);
4550     } else if(r->is_young()) {
4551       r->uninstall_surv_rate_group();
4552     } else {
4553       // We ignore free regions, we'll empty the free list afterwards.
4554       // We ignore humongous and archive regions, we're not tearing down these
4555       // sets.
4556       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4557              "it cannot be another type");
4558     }
4559     return false;
4560   }
4561 
4562   ~TearDownRegionSetsClosure() {
4563     assert(_old_set->is_empty(), "post-condition");
4564   }
4565 };
4566 
4567 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4568   assert_at_safepoint_on_vm_thread();
4569 
4570   if (!free_list_only) {
4571     TearDownRegionSetsClosure cl(&_old_set);
4572     heap_region_iterate(&cl);
4573 
4574     // Note that emptying the _young_list is postponed and instead done as
4575     // the first step when rebuilding the regions sets again. The reason for
4576     // this is that during a full GC string deduplication needs to know if
4577     // a collected region was young or old when the full GC was initiated.
4578   }
4579   _hrm->remove_all_free_regions();
4580 }
4581 
4582 void G1CollectedHeap::increase_used(size_t bytes) {
4583   _summary_bytes_used += bytes;
4584 }
4585 
4586 void G1CollectedHeap::decrease_used(size_t bytes) {
4587   assert(_summary_bytes_used >= bytes,
4588          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4589          _summary_bytes_used, bytes);
4590   _summary_bytes_used -= bytes;
4591 }
4592 
4593 void G1CollectedHeap::set_used(size_t bytes) {
4594   _summary_bytes_used = bytes;
4595 }
4596 
4597 class RebuildRegionSetsClosure : public HeapRegionClosure {
4598 private:
4599   bool _free_list_only;
4600 
4601   HeapRegionSet* _old_set;
4602   HeapRegionManager* _hrm;
4603 
4604   size_t _total_used;
4605 
4606 public:
4607   RebuildRegionSetsClosure(bool free_list_only,
4608                            HeapRegionSet* old_set,
4609                            HeapRegionManager* hrm) :
4610     _free_list_only(free_list_only),
4611     _old_set(old_set), _hrm(hrm), _total_used(0) {
4612     assert(_hrm->num_free_regions() == 0, "pre-condition");
4613     if (!free_list_only) {
4614       assert(_old_set->is_empty(), "pre-condition");
4615     }
4616   }
4617 
4618   bool do_heap_region(HeapRegion* r) {
4619     if (r->is_empty()) {
4620       assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4621       // Add free regions to the free list
4622       r->set_free();
4623       _hrm->insert_into_free_list(r);
4624     } else if (!_free_list_only) {
4625       assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4626 
4627       if (r->is_archive() || r->is_humongous()) {
4628         // We ignore archive and humongous regions. We left these sets unchanged.
4629       } else {
4630         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4631         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4632         r->move_to_old();
4633         _old_set->add(r);
4634       }
4635       _total_used += r->used();
4636     }
4637 
4638     return false;
4639   }
4640 
4641   size_t total_used() {
4642     return _total_used;
4643   }
4644 };
4645 
4646 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4647   assert_at_safepoint_on_vm_thread();
4648 
4649   if (!free_list_only) {
4650     _eden.clear();
4651     _survivor.clear();
4652   }
4653 
4654   RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4655   heap_region_iterate(&cl);
4656 
4657   if (!free_list_only) {
4658     set_used(cl.total_used());
4659     if (_archive_allocator != NULL) {
4660       _archive_allocator->clear_used();
4661     }
4662   }
4663   assert(used() == recalculate_used(),
4664          "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4665          used(), recalculate_used());
4666 }
4667 
4668 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4669   HeapRegion* hr = heap_region_containing(p);
4670   return hr->is_in(p);
4671 }
4672 
4673 // Methods for the mutator alloc region
4674 
4675 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4676                                                       bool force) {
4677   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4678   bool should_allocate = g1_policy()->should_allocate_mutator_region();
4679   if (force || should_allocate) {
4680     HeapRegion* new_alloc_region = new_region(word_size,
4681                                               HeapRegionType::Eden,
4682                                               false /* do_expand */);
4683     if (new_alloc_region != NULL) {
4684       set_region_short_lived_locked(new_alloc_region);
4685       _hr_printer.alloc(new_alloc_region, !should_allocate);
4686       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4687       _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4688       return new_alloc_region;
4689     }
4690   }
4691   return NULL;
4692 }
4693 
4694 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4695                                                   size_t allocated_bytes) {
4696   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4697   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4698 
4699   collection_set()->add_eden_region(alloc_region);
4700   increase_used(allocated_bytes);
4701   _hr_printer.retire(alloc_region);
4702   // We update the eden sizes here, when the region is retired,
4703   // instead of when it's allocated, since this is the point that its
4704   // used space has been recorded in _summary_bytes_used.
4705   g1mm()->update_eden_size();
4706 }
4707 
4708 // Methods for the GC alloc regions
4709 
4710 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4711   if (dest.is_old()) {
4712     return true;
4713   } else {
4714     return survivor_regions_count() < g1_policy()->max_survivor_regions();
4715   }
4716 }
4717 
4718 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4719   assert(FreeList_lock->owned_by_self(), "pre-condition");
4720 
4721   if (!has_more_regions(dest)) {
4722     return NULL;
4723   }
4724 
4725   HeapRegionType type;
4726   if (dest.is_young()) {
4727     type = HeapRegionType::Survivor;
4728   } else {
4729     type = HeapRegionType::Old;
4730   }
4731 
4732   HeapRegion* new_alloc_region = new_region(word_size,
4733                                             type,
4734                                             true /* do_expand */);
4735 
4736   if (new_alloc_region != NULL) {
4737     if (type.is_survivor()) {
4738       new_alloc_region->set_survivor();
4739       _survivor.add(new_alloc_region);
4740       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4741     } else {
4742       new_alloc_region->set_old();
4743       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4744     }
4745     _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4746     _hr_printer.alloc(new_alloc_region);
4747     return new_alloc_region;
4748   }
4749   return NULL;
4750 }
4751 
4752 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4753                                              size_t allocated_bytes,
4754                                              InCSetState dest) {
4755   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4756   if (dest.is_old()) {
4757     old_set_add(alloc_region);
4758   }
4759 
4760   bool const during_im = collector_state()->in_initial_mark_gc();
4761   if (during_im && allocated_bytes > 0) {
4762     _cm->root_regions()->add(alloc_region);
4763   }
4764   _hr_printer.retire(alloc_region);
4765 }
4766 
4767 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4768   bool expanded = false;
4769   uint index = _hrm->find_highest_free(&expanded);
4770 
4771   if (index != G1_NO_HRM_INDEX) {
4772     if (expanded) {
4773       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4774                                 HeapRegion::GrainWords * HeapWordSize);
4775     }
4776     _hrm->allocate_free_regions_starting_at(index, 1);
4777     return region_at(index);
4778   }
4779   return NULL;
4780 }
4781 
4782 // Optimized nmethod scanning
4783 
4784 class RegisterNMethodOopClosure: public OopClosure {
4785   G1CollectedHeap* _g1h;
4786   nmethod* _nm;
4787 
4788   template <class T> void do_oop_work(T* p) {
4789     T heap_oop = RawAccess<>::oop_load(p);
4790     if (!CompressedOops::is_null(heap_oop)) {
4791       oop obj = CompressedOops::decode_not_null(heap_oop);
4792       HeapRegion* hr = _g1h->heap_region_containing(obj);
4793       assert(!hr->is_continues_humongous(),
4794              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4795              " starting at " HR_FORMAT,
4796              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4797 
4798       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4799       hr->add_strong_code_root_locked(_nm);
4800     }
4801   }
4802 
4803 public:
4804   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4805     _g1h(g1h), _nm(nm) {}
4806 
4807   void do_oop(oop* p)       { do_oop_work(p); }
4808   void do_oop(narrowOop* p) { do_oop_work(p); }
4809 };
4810 
4811 class UnregisterNMethodOopClosure: public OopClosure {
4812   G1CollectedHeap* _g1h;
4813   nmethod* _nm;
4814 
4815   template <class T> void do_oop_work(T* p) {
4816     T heap_oop = RawAccess<>::oop_load(p);
4817     if (!CompressedOops::is_null(heap_oop)) {
4818       oop obj = CompressedOops::decode_not_null(heap_oop);
4819       HeapRegion* hr = _g1h->heap_region_containing(obj);
4820       assert(!hr->is_continues_humongous(),
4821              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4822              " starting at " HR_FORMAT,
4823              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4824 
4825       hr->remove_strong_code_root(_nm);
4826     }
4827   }
4828 
4829 public:
4830   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4831     _g1h(g1h), _nm(nm) {}
4832 
4833   void do_oop(oop* p)       { do_oop_work(p); }
4834   void do_oop(narrowOop* p) { do_oop_work(p); }
4835 };
4836 
4837 // Returns true if the reference points to an object that
4838 // can move in an incremental collection.
4839 bool G1CollectedHeap::is_scavengable(oop obj) {
4840   HeapRegion* hr = heap_region_containing(obj);
4841   return !hr->is_pinned();
4842 }
4843 
4844 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4845   guarantee(nm != NULL, "sanity");
4846   RegisterNMethodOopClosure reg_cl(this, nm);
4847   nm->oops_do(&reg_cl);
4848 }
4849 
4850 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4851   guarantee(nm != NULL, "sanity");
4852   UnregisterNMethodOopClosure reg_cl(this, nm);
4853   nm->oops_do(&reg_cl, true);
4854 }
4855 
4856 void G1CollectedHeap::purge_code_root_memory() {
4857   double purge_start = os::elapsedTime();
4858   G1CodeRootSet::purge();
4859   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4860   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4861 }
4862 
4863 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4864   G1CollectedHeap* _g1h;
4865 
4866 public:
4867   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4868     _g1h(g1h) {}
4869 
4870   void do_code_blob(CodeBlob* cb) {
4871     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4872     if (nm == NULL) {
4873       return;
4874     }
4875 
4876     if (ScavengeRootsInCode) {
4877       _g1h->register_nmethod(nm);
4878     }
4879   }
4880 };
4881 
4882 void G1CollectedHeap::rebuild_strong_code_roots() {
4883   RebuildStrongCodeRootClosure blob_cl(this);
4884   CodeCache::blobs_do(&blob_cl);
4885 }
4886 
4887 void G1CollectedHeap::initialize_serviceability() {
4888   _g1mm->initialize_serviceability();
4889 }
4890 
4891 MemoryUsage G1CollectedHeap::memory_usage() {
4892   return _g1mm->memory_usage();
4893 }
4894 
4895 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4896   return _g1mm->memory_managers();
4897 }
4898 
4899 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4900   return _g1mm->memory_pools();
4901 }
--- EOF ---