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/g1Arguments.hpp"
  33 #include "gc/g1/g1BarrierSet.hpp"
  34 #include "gc/g1/g1CardTableEntryClosure.hpp"
  35 #include "gc/g1/g1CollectedHeap.inline.hpp"
  36 #include "gc/g1/g1CollectionSet.hpp"
  37 #include "gc/g1/g1CollectorState.hpp"
  38 #include "gc/g1/g1ConcurrentRefine.hpp"
  39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
  40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
  41 #include "gc/g1/g1DirtyCardQueue.hpp"
  42 #include "gc/g1/g1EvacStats.inline.hpp"
  43 #include "gc/g1/g1FullCollector.hpp"
  44 #include "gc/g1/g1GCPhaseTimes.hpp"
  45 #include "gc/g1/g1HeapSizingPolicy.hpp"
  46 #include "gc/g1/g1HeapTransition.hpp"
  47 #include "gc/g1/g1HeapVerifier.hpp"
  48 #include "gc/g1/g1HotCardCache.hpp"
  49 #include "gc/g1/g1MemoryPool.hpp"
  50 #include "gc/g1/g1OopClosures.inline.hpp"
  51 #include "gc/g1/g1ParallelCleaning.hpp"
  52 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  53 #include "gc/g1/g1Policy.hpp"
  54 #include "gc/g1/g1RedirtyCardsQueue.hpp"
  55 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  56 #include "gc/g1/g1RemSet.hpp"
  57 #include "gc/g1/g1RootClosures.hpp"
  58 #include "gc/g1/g1RootProcessor.hpp"
  59 #include "gc/g1/g1SATBMarkQueueSet.hpp"
  60 #include "gc/g1/g1StringDedup.hpp"
  61 #include "gc/g1/g1ThreadLocalData.hpp"
  62 #include "gc/g1/g1Trace.hpp"
  63 #include "gc/g1/g1YCTypes.hpp"
  64 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  65 #include "gc/g1/g1VMOperations.hpp"
  66 #include "gc/g1/heapRegion.inline.hpp"
  67 #include "gc/g1/heapRegionRemSet.hpp"
  68 #include "gc/g1/heapRegionSet.inline.hpp"
  69 #include "gc/shared/gcBehaviours.hpp"
  70 #include "gc/shared/gcHeapSummary.hpp"
  71 #include "gc/shared/gcId.hpp"
  72 #include "gc/shared/gcLocker.hpp"
  73 #include "gc/shared/gcTimer.hpp"
  74 #include "gc/shared/gcTraceTime.inline.hpp"
  75 #include "gc/shared/generationSpec.hpp"
  76 #include "gc/shared/isGCActiveMark.hpp"
  77 #include "gc/shared/locationPrinter.inline.hpp"
  78 #include "gc/shared/oopStorageParState.hpp"
  79 #include "gc/shared/preservedMarks.inline.hpp"
  80 #include "gc/shared/suspendibleThreadSet.hpp"
  81 #include "gc/shared/referenceProcessor.inline.hpp"
  82 #include "gc/shared/taskqueue.inline.hpp"
  83 #include "gc/shared/weakProcessor.inline.hpp"
  84 #include "gc/shared/workerPolicy.hpp"
  85 #include "logging/log.hpp"
  86 #include "memory/allocation.hpp"
  87 #include "memory/iterator.hpp"
  88 #include "memory/resourceArea.hpp"
  89 #include "memory/universe.hpp"
  90 #include "oops/access.inline.hpp"
  91 #include "oops/compressedOops.inline.hpp"
  92 #include "oops/oop.inline.hpp"
  93 #include "runtime/atomic.hpp"
  94 #include "runtime/flags/flagSetting.hpp"
  95 #include "runtime/handles.inline.hpp"
  96 #include "runtime/init.hpp"
  97 #include "runtime/orderAccess.hpp"
  98 #include "runtime/threadSMR.hpp"
  99 #include "runtime/vmThread.hpp"
 100 #include "utilities/align.hpp"
 101 #include "utilities/globalDefinitions.hpp"
 102 #include "utilities/stack.inline.hpp"
 103 
 104 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
 105 
 106 // INVARIANTS/NOTES
 107 //
 108 // All allocation activity covered by the G1CollectedHeap interface is
 109 // serialized by acquiring the HeapLock.  This happens in mem_allocate
 110 // and allocate_new_tlab, which are the "entry" points to the
 111 // allocation code from the rest of the JVM.  (Note that this does not
 112 // apply to TLAB allocation, which is not part of this interface: it
 113 // is done by clients of this interface.)
 114 
 115 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
 116  private:
 117   size_t _num_dirtied;
 118   G1CollectedHeap* _g1h;
 119   G1CardTable* _g1_ct;
 120 
 121   HeapRegion* region_for_card(CardValue* card_ptr) const {
 122     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
 123   }
 124 
 125   bool will_become_free(HeapRegion* hr) const {
 126     // A region will be freed by free_collection_set if the region is in the
 127     // collection set and has not had an evacuation failure.
 128     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 129   }
 130 
 131  public:
 132   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
 133     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
 134 
 135   void do_card_ptr(CardValue* card_ptr, uint worker_id) {
 136     HeapRegion* hr = region_for_card(card_ptr);
 137 
 138     // Should only dirty cards in regions that won't be freed.
 139     if (!will_become_free(hr)) {
 140       *card_ptr = G1CardTable::dirty_card_val();
 141       _num_dirtied++;
 142     }
 143   }
 144 
 145   size_t num_dirtied()   const { return _num_dirtied; }
 146 };
 147 
 148 
 149 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 150   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 151 }
 152 
 153 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 154   // The from card cache is not the memory that is actually committed. So we cannot
 155   // take advantage of the zero_filled parameter.
 156   reset_from_card_cache(start_idx, num_regions);
 157 }
 158 
 159 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
 160   Ticks start = Ticks::now();
 161   workers()->run_task(task, workers()->active_workers());
 162   return Ticks::now() - start;
 163 }
 164 
 165 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 166                                              MemRegion mr) {
 167   return new HeapRegion(hrs_index, bot(), mr);
 168 }
 169 
 170 // Private methods.
 171 
 172 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
 173                                         HeapRegionType type,
 174                                         bool do_expand,
 175                                         uint node_index) {
 176   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 177          "the only time we use this to allocate a humongous region is "
 178          "when we are allocating a single humongous region");
 179 
 180   HeapRegion* res = _hrm->allocate_free_region(type, node_index);
 181 
 182   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 183     // Currently, only attempts to allocate GC alloc regions set
 184     // do_expand to true. So, we should only reach here during a
 185     // safepoint. If this assumption changes we might have to
 186     // reconsider the use of _expand_heap_after_alloc_failure.
 187     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 188 
 189     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 190                               word_size * HeapWordSize);
 191 
 192     assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
 193            "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
 194            word_size * HeapWordSize);
 195     if (expand_single_region(node_index)) {
 196       // Given that expand_single_region() succeeded in expanding the heap, and we
 197       // always expand the heap by an amount aligned to the heap
 198       // region size, the free list should in theory not be empty.
 199       // In either case allocate_free_region() will check for NULL.
 200       res = _hrm->allocate_free_region(type, node_index);
 201     } else {
 202       _expand_heap_after_alloc_failure = false;
 203     }
 204   }
 205   return res;
 206 }
 207 
 208 HeapWord*
 209 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 210                                                            uint num_regions,
 211                                                            size_t word_size) {
 212   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 213   assert(is_humongous(word_size), "word_size should be humongous");
 214   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 215 
 216   // Index of last region in the series.
 217   uint last = first + num_regions - 1;
 218 
 219   // We need to initialize the region(s) we just discovered. This is
 220   // a bit tricky given that it can happen concurrently with
 221   // refinement threads refining cards on these regions and
 222   // potentially wanting to refine the BOT as they are scanning
 223   // those cards (this can happen shortly after a cleanup; see CR
 224   // 6991377). So we have to set up the region(s) carefully and in
 225   // a specific order.
 226 
 227   // The word size sum of all the regions we will allocate.
 228   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 229   assert(word_size <= word_size_sum, "sanity");
 230 
 231   // This will be the "starts humongous" region.
 232   HeapRegion* first_hr = region_at(first);
 233   // The header of the new object will be placed at the bottom of
 234   // the first region.
 235   HeapWord* new_obj = first_hr->bottom();
 236   // This will be the new top of the new object.
 237   HeapWord* obj_top = new_obj + word_size;
 238 
 239   // First, we need to zero the header of the space that we will be
 240   // allocating. When we update top further down, some refinement
 241   // threads might try to scan the region. By zeroing the header we
 242   // ensure that any thread that will try to scan the region will
 243   // come across the zero klass word and bail out.
 244   //
 245   // NOTE: It would not have been correct to have used
 246   // CollectedHeap::fill_with_object() and make the space look like
 247   // an int array. The thread that is doing the allocation will
 248   // later update the object header to a potentially different array
 249   // type and, for a very short period of time, the klass and length
 250   // fields will be inconsistent. This could cause a refinement
 251   // thread to calculate the object size incorrectly.
 252   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 253 
 254   // Next, pad out the unused tail of the last region with filler
 255   // objects, for improved usage accounting.
 256   // How many words we use for filler objects.
 257   size_t word_fill_size = word_size_sum - word_size;
 258 
 259   // How many words memory we "waste" which cannot hold a filler object.
 260   size_t words_not_fillable = 0;
 261 
 262   if (word_fill_size >= min_fill_size()) {
 263     fill_with_objects(obj_top, word_fill_size);
 264   } else if (word_fill_size > 0) {
 265     // We have space to fill, but we cannot fit an object there.
 266     words_not_fillable = word_fill_size;
 267     word_fill_size = 0;
 268   }
 269 
 270   // We will set up the first region as "starts humongous". This
 271   // will also update the BOT covering all the regions to reflect
 272   // that there is a single object that starts at the bottom of the
 273   // first region.
 274   first_hr->set_starts_humongous(obj_top, word_fill_size);
 275   _policy->remset_tracker()->update_at_allocate(first_hr);
 276   // Then, if there are any, we will set up the "continues
 277   // humongous" regions.
 278   HeapRegion* hr = NULL;
 279   for (uint i = first + 1; i <= last; ++i) {
 280     hr = region_at(i);
 281     hr->set_continues_humongous(first_hr);
 282     _policy->remset_tracker()->update_at_allocate(hr);
 283   }
 284 
 285   // Up to this point no concurrent thread would have been able to
 286   // do any scanning on any region in this series. All the top
 287   // fields still point to bottom, so the intersection between
 288   // [bottom,top] and [card_start,card_end] will be empty. Before we
 289   // update the top fields, we'll do a storestore to make sure that
 290   // no thread sees the update to top before the zeroing of the
 291   // object header and the BOT initialization.
 292   OrderAccess::storestore();
 293 
 294   // Now, we will update the top fields of the "continues humongous"
 295   // regions except the last one.
 296   for (uint i = first; i < last; ++i) {
 297     hr = region_at(i);
 298     hr->set_top(hr->end());
 299   }
 300 
 301   hr = region_at(last);
 302   // If we cannot fit a filler object, we must set top to the end
 303   // of the humongous object, otherwise we cannot iterate the heap
 304   // and the BOT will not be complete.
 305   hr->set_top(hr->end() - words_not_fillable);
 306 
 307   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 308          "obj_top should be in last region");
 309 
 310   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 311 
 312   assert(words_not_fillable == 0 ||
 313          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 314          "Miscalculation in humongous allocation");
 315 
 316   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 317 
 318   for (uint i = first; i <= last; ++i) {
 319     hr = region_at(i);
 320     _humongous_set.add(hr);
 321     _hr_printer.alloc(hr);
 322   }
 323 
 324   return new_obj;
 325 }
 326 
 327 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 328   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 329   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 330 }
 331 
 332 // If could fit into free regions w/o expansion, try.
 333 // Otherwise, if can expand, do so.
 334 // Otherwise, if using ex regions might help, try with ex given back.
 335 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 336   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 337 
 338   _verifier->verify_region_sets_optional();
 339 
 340   uint first = G1_NO_HRM_INDEX;
 341   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 342 
 343   if (obj_regions == 1) {
 344     // Only one region to allocate, try to use a fast path by directly allocating
 345     // from the free lists. Do not try to expand here, we will potentially do that
 346     // later.
 347     HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
 348     if (hr != NULL) {
 349       first = hr->hrm_index();
 350     }
 351   } else {
 352     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 353     // are lucky enough to find some.
 354     first = _hrm->find_contiguous_only_empty(obj_regions);
 355     if (first != G1_NO_HRM_INDEX) {
 356       _hrm->allocate_free_regions_starting_at(first, obj_regions);
 357     }
 358   }
 359 
 360   if (first == G1_NO_HRM_INDEX) {
 361     // Policy: We could not find enough regions for the humongous object in the
 362     // free list. Look through the heap to find a mix of free and uncommitted regions.
 363     // If so, try expansion.
 364     first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
 365     if (first != G1_NO_HRM_INDEX) {
 366       // We found something. Make sure these regions are committed, i.e. expand
 367       // the heap. Alternatively we could do a defragmentation GC.
 368       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 369                                     word_size * HeapWordSize);
 370 
 371       _hrm->expand_at(first, obj_regions, workers());
 372       policy()->record_new_heap_size(num_regions());
 373 
 374 #ifdef ASSERT
 375       for (uint i = first; i < first + obj_regions; ++i) {
 376         HeapRegion* hr = region_at(i);
 377         assert(hr->is_free(), "sanity");
 378         assert(hr->is_empty(), "sanity");
 379         assert(is_on_master_free_list(hr), "sanity");
 380       }
 381 #endif
 382       _hrm->allocate_free_regions_starting_at(first, obj_regions);
 383     } else {
 384       // Policy: Potentially trigger a defragmentation GC.
 385     }
 386   }
 387 
 388   HeapWord* result = NULL;
 389   if (first != G1_NO_HRM_INDEX) {
 390     result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
 391     assert(result != NULL, "it should always return a valid result");
 392 
 393     // A successful humongous object allocation changes the used space
 394     // information of the old generation so we need to recalculate the
 395     // sizes and update the jstat counters here.
 396     g1mm()->update_sizes();
 397   }
 398 
 399   _verifier->verify_region_sets_optional();
 400 
 401   return result;
 402 }
 403 
 404 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
 405                                              size_t requested_size,
 406                                              size_t* actual_size) {
 407   assert_heap_not_locked_and_not_at_safepoint();
 408   assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
 409 
 410   return attempt_allocation(min_size, requested_size, actual_size);
 411 }
 412 
 413 HeapWord*
 414 G1CollectedHeap::mem_allocate(size_t word_size,
 415                               bool*  gc_overhead_limit_was_exceeded) {
 416   assert_heap_not_locked_and_not_at_safepoint();
 417 
 418   if (is_humongous(word_size)) {
 419     return attempt_allocation_humongous(word_size);
 420   }
 421   size_t dummy = 0;
 422   return attempt_allocation(word_size, word_size, &dummy);
 423 }
 424 
 425 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 426   ResourceMark rm; // For retrieving the thread names in log messages.
 427 
 428   // Make sure you read the note in attempt_allocation_humongous().
 429 
 430   assert_heap_not_locked_and_not_at_safepoint();
 431   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 432          "be called for humongous allocation requests");
 433 
 434   // We should only get here after the first-level allocation attempt
 435   // (attempt_allocation()) failed to allocate.
 436 
 437   // We will loop until a) we manage to successfully perform the
 438   // allocation or b) we successfully schedule a collection which
 439   // fails to perform the allocation. b) is the only case when we'll
 440   // return NULL.
 441   HeapWord* result = NULL;
 442   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 443     bool should_try_gc;
 444     uint gc_count_before;
 445 
 446     {
 447       MutexLocker x(Heap_lock);
 448       result = _allocator->attempt_allocation_locked(word_size);
 449       if (result != NULL) {
 450         return result;
 451       }
 452 
 453       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 454       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 455       // waiting because the GCLocker is active to not wait too long.
 456       if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
 457         // No need for an ergo message here, can_expand_young_list() does this when
 458         // it returns true.
 459         result = _allocator->attempt_allocation_force(word_size);
 460         if (result != NULL) {
 461           return result;
 462         }
 463       }
 464       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 465       // the GCLocker initiated GC has been performed and then retry. This includes
 466       // the case when the GC Locker is not active but has not been performed.
 467       should_try_gc = !GCLocker::needs_gc();
 468       // Read the GC count while still holding the Heap_lock.
 469       gc_count_before = total_collections();
 470     }
 471 
 472     if (should_try_gc) {
 473       bool succeeded;
 474       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 475                                    GCCause::_g1_inc_collection_pause);
 476       if (result != NULL) {
 477         assert(succeeded, "only way to get back a non-NULL result");
 478         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 479                              Thread::current()->name(), p2i(result));
 480         return result;
 481       }
 482 
 483       if (succeeded) {
 484         // We successfully scheduled a collection which failed to allocate. No
 485         // point in trying to allocate further. We'll just return NULL.
 486         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 487                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 488         return NULL;
 489       }
 490       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 491                            Thread::current()->name(), word_size);
 492     } else {
 493       // Failed to schedule a collection.
 494       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 495         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 496                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 497         return NULL;
 498       }
 499       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 500       // The GCLocker is either active or the GCLocker initiated
 501       // GC has not yet been performed. Stall until it is and
 502       // then retry the allocation.
 503       GCLocker::stall_until_clear();
 504       gclocker_retry_count += 1;
 505     }
 506 
 507     // We can reach here if we were unsuccessful in scheduling a
 508     // collection (because another thread beat us to it) or if we were
 509     // stalled due to the GC locker. In either can we should retry the
 510     // allocation attempt in case another thread successfully
 511     // performed a collection and reclaimed enough space. We do the
 512     // first attempt (without holding the Heap_lock) here and the
 513     // follow-on attempt will be at the start of the next loop
 514     // iteration (after taking the Heap_lock).
 515     size_t dummy = 0;
 516     result = _allocator->attempt_allocation(word_size, word_size, &dummy);
 517     if (result != NULL) {
 518       return result;
 519     }
 520 
 521     // Give a warning if we seem to be looping forever.
 522     if ((QueuedAllocationWarningCount > 0) &&
 523         (try_count % QueuedAllocationWarningCount == 0)) {
 524       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 525                              Thread::current()->name(), try_count, word_size);
 526     }
 527   }
 528 
 529   ShouldNotReachHere();
 530   return NULL;
 531 }
 532 
 533 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 534   assert_at_safepoint_on_vm_thread();
 535   if (_archive_allocator == NULL) {
 536     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 537   }
 538 }
 539 
 540 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 541   // Allocations in archive regions cannot be of a size that would be considered
 542   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 543   // may be different at archive-restore time.
 544   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 545 }
 546 
 547 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 548   assert_at_safepoint_on_vm_thread();
 549   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 550   if (is_archive_alloc_too_large(word_size)) {
 551     return NULL;
 552   }
 553   return _archive_allocator->archive_mem_allocate(word_size);
 554 }
 555 
 556 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 557                                               size_t end_alignment_in_bytes) {
 558   assert_at_safepoint_on_vm_thread();
 559   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 560 
 561   // Call complete_archive to do the real work, filling in the MemRegion
 562   // array with the archive regions.
 563   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 564   delete _archive_allocator;
 565   _archive_allocator = NULL;
 566 }
 567 
 568 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 569   assert(ranges != NULL, "MemRegion array NULL");
 570   assert(count != 0, "No MemRegions provided");
 571   MemRegion reserved = _hrm->reserved();
 572   for (size_t i = 0; i < count; i++) {
 573     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 574       return false;
 575     }
 576   }
 577   return true;
 578 }
 579 
 580 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 581                                             size_t count,
 582                                             bool open) {
 583   assert(!is_init_completed(), "Expect to be called at JVM init time");
 584   assert(ranges != NULL, "MemRegion array NULL");
 585   assert(count != 0, "No MemRegions provided");
 586   MutexLocker x(Heap_lock);
 587 
 588   MemRegion reserved = _hrm->reserved();
 589   HeapWord* prev_last_addr = NULL;
 590   HeapRegion* prev_last_region = NULL;
 591 
 592   // Temporarily disable pretouching of heap pages. This interface is used
 593   // when mmap'ing archived heap data in, so pre-touching is wasted.
 594   FlagSetting fs(AlwaysPreTouch, false);
 595 
 596   // Enable archive object checking used by G1MarkSweep. We have to let it know
 597   // about each archive range, so that objects in those ranges aren't marked.
 598   G1ArchiveAllocator::enable_archive_object_check();
 599 
 600   // For each specified MemRegion range, allocate the corresponding G1
 601   // regions and mark them as archive regions. We expect the ranges
 602   // in ascending starting address order, without overlap.
 603   for (size_t i = 0; i < count; i++) {
 604     MemRegion curr_range = ranges[i];
 605     HeapWord* start_address = curr_range.start();
 606     size_t word_size = curr_range.word_size();
 607     HeapWord* last_address = curr_range.last();
 608     size_t commits = 0;
 609 
 610     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 611               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 612               p2i(start_address), p2i(last_address));
 613     guarantee(start_address > prev_last_addr,
 614               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 615               p2i(start_address), p2i(prev_last_addr));
 616     prev_last_addr = last_address;
 617 
 618     // Check for ranges that start in the same G1 region in which the previous
 619     // range ended, and adjust the start address so we don't try to allocate
 620     // the same region again. If the current range is entirely within that
 621     // region, skip it, just adjusting the recorded top.
 622     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 623     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 624       start_address = start_region->end();
 625       if (start_address > last_address) {
 626         increase_used(word_size * HeapWordSize);
 627         start_region->set_top(last_address + 1);
 628         continue;
 629       }
 630       start_region->set_top(start_address);
 631       curr_range = MemRegion(start_address, last_address + 1);
 632       start_region = _hrm->addr_to_region(start_address);
 633     }
 634 
 635     // Perform the actual region allocation, exiting if it fails.
 636     // Then note how much new space we have allocated.
 637     if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
 638       return false;
 639     }
 640     increase_used(word_size * HeapWordSize);
 641     if (commits != 0) {
 642       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 643                                 HeapRegion::GrainWords * HeapWordSize * commits);
 644 
 645     }
 646 
 647     // Mark each G1 region touched by the range as archive, add it to
 648     // the old set, and set top.
 649     HeapRegion* curr_region = _hrm->addr_to_region(start_address);
 650     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 651     prev_last_region = last_region;
 652 
 653     while (curr_region != NULL) {
 654       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 655              "Region already in use (index %u)", curr_region->hrm_index());
 656       if (open) {
 657         curr_region->set_open_archive();
 658       } else {
 659         curr_region->set_closed_archive();
 660       }
 661       _hr_printer.alloc(curr_region);
 662       _archive_set.add(curr_region);
 663       HeapWord* top;
 664       HeapRegion* next_region;
 665       if (curr_region != last_region) {
 666         top = curr_region->end();
 667         next_region = _hrm->next_region_in_heap(curr_region);
 668       } else {
 669         top = last_address + 1;
 670         next_region = NULL;
 671       }
 672       curr_region->set_top(top);
 673       curr_region->set_first_dead(top);
 674       curr_region->set_end_of_live(top);
 675       curr_region = next_region;
 676     }
 677 
 678     // Notify mark-sweep of the archive
 679     G1ArchiveAllocator::set_range_archive(curr_range, open);
 680   }
 681   return true;
 682 }
 683 
 684 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 685   assert(!is_init_completed(), "Expect to be called at JVM init time");
 686   assert(ranges != NULL, "MemRegion array NULL");
 687   assert(count != 0, "No MemRegions provided");
 688   MemRegion reserved = _hrm->reserved();
 689   HeapWord *prev_last_addr = NULL;
 690   HeapRegion* prev_last_region = NULL;
 691 
 692   // For each MemRegion, create filler objects, if needed, in the G1 regions
 693   // that contain the address range. The address range actually within the
 694   // MemRegion will not be modified. That is assumed to have been initialized
 695   // elsewhere, probably via an mmap of archived heap data.
 696   MutexLocker x(Heap_lock);
 697   for (size_t i = 0; i < count; i++) {
 698     HeapWord* start_address = ranges[i].start();
 699     HeapWord* last_address = ranges[i].last();
 700 
 701     assert(reserved.contains(start_address) && reserved.contains(last_address),
 702            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 703            p2i(start_address), p2i(last_address));
 704     assert(start_address > prev_last_addr,
 705            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 706            p2i(start_address), p2i(prev_last_addr));
 707 
 708     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 709     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 710     HeapWord* bottom_address = start_region->bottom();
 711 
 712     // Check for a range beginning in the same region in which the
 713     // previous one ended.
 714     if (start_region == prev_last_region) {
 715       bottom_address = prev_last_addr + 1;
 716     }
 717 
 718     // Verify that the regions were all marked as archive regions by
 719     // alloc_archive_regions.
 720     HeapRegion* curr_region = start_region;
 721     while (curr_region != NULL) {
 722       guarantee(curr_region->is_archive(),
 723                 "Expected archive region at index %u", curr_region->hrm_index());
 724       if (curr_region != last_region) {
 725         curr_region = _hrm->next_region_in_heap(curr_region);
 726       } else {
 727         curr_region = NULL;
 728       }
 729     }
 730 
 731     prev_last_addr = last_address;
 732     prev_last_region = last_region;
 733 
 734     // Fill the memory below the allocated range with dummy object(s),
 735     // if the region bottom does not match the range start, or if the previous
 736     // range ended within the same G1 region, and there is a gap.
 737     if (start_address != bottom_address) {
 738       size_t fill_size = pointer_delta(start_address, bottom_address);
 739       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 740       increase_used(fill_size * HeapWordSize);
 741     }
 742   }
 743 }
 744 
 745 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
 746                                                      size_t desired_word_size,
 747                                                      size_t* actual_word_size) {
 748   assert_heap_not_locked_and_not_at_safepoint();
 749   assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
 750          "be called for humongous allocation requests");
 751 
 752   HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
 753 
 754   if (result == NULL) {
 755     *actual_word_size = desired_word_size;
 756     result = attempt_allocation_slow(desired_word_size);
 757   }
 758 
 759   assert_heap_not_locked();
 760   if (result != NULL) {
 761     assert(*actual_word_size != 0, "Actual size must have been set here");
 762     dirty_young_block(result, *actual_word_size);
 763   } else {
 764     *actual_word_size = 0;
 765   }
 766 
 767   return result;
 768 }
 769 
 770 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
 771   assert(!is_init_completed(), "Expect to be called at JVM init time");
 772   assert(ranges != NULL, "MemRegion array NULL");
 773   assert(count != 0, "No MemRegions provided");
 774   MemRegion reserved = _hrm->reserved();
 775   HeapWord* prev_last_addr = NULL;
 776   HeapRegion* prev_last_region = NULL;
 777   size_t size_used = 0;
 778   size_t uncommitted_regions = 0;
 779 
 780   // For each Memregion, free the G1 regions that constitute it, and
 781   // notify mark-sweep that the range is no longer to be considered 'archive.'
 782   MutexLocker x(Heap_lock);
 783   for (size_t i = 0; i < count; i++) {
 784     HeapWord* start_address = ranges[i].start();
 785     HeapWord* last_address = ranges[i].last();
 786 
 787     assert(reserved.contains(start_address) && reserved.contains(last_address),
 788            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 789            p2i(start_address), p2i(last_address));
 790     assert(start_address > prev_last_addr,
 791            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 792            p2i(start_address), p2i(prev_last_addr));
 793     size_used += ranges[i].byte_size();
 794     prev_last_addr = last_address;
 795 
 796     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 797     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 798 
 799     // Check for ranges that start in the same G1 region in which the previous
 800     // range ended, and adjust the start address so we don't try to free
 801     // the same region again. If the current range is entirely within that
 802     // region, skip it.
 803     if (start_region == prev_last_region) {
 804       start_address = start_region->end();
 805       if (start_address > last_address) {
 806         continue;
 807       }
 808       start_region = _hrm->addr_to_region(start_address);
 809     }
 810     prev_last_region = last_region;
 811 
 812     // After verifying that each region was marked as an archive region by
 813     // alloc_archive_regions, set it free and empty and uncommit it.
 814     HeapRegion* curr_region = start_region;
 815     while (curr_region != NULL) {
 816       guarantee(curr_region->is_archive(),
 817                 "Expected archive region at index %u", curr_region->hrm_index());
 818       uint curr_index = curr_region->hrm_index();
 819       _archive_set.remove(curr_region);
 820       curr_region->set_free();
 821       curr_region->set_top(curr_region->bottom());
 822       if (curr_region != last_region) {
 823         curr_region = _hrm->next_region_in_heap(curr_region);
 824       } else {
 825         curr_region = NULL;
 826       }
 827       _hrm->shrink_at(curr_index, 1);
 828       uncommitted_regions++;
 829     }
 830 
 831     // Notify mark-sweep that this is no longer an archive range.
 832     G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
 833   }
 834 
 835   if (uncommitted_regions != 0) {
 836     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 837                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 838   }
 839   decrease_used(size_used);
 840 }
 841 
 842 oop G1CollectedHeap::materialize_archived_object(oop obj) {
 843   assert(obj != NULL, "archived obj is NULL");
 844   assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
 845 
 846   // Loading an archived object makes it strongly reachable. If it is
 847   // loaded during concurrent marking, it must be enqueued to the SATB
 848   // queue, shading the previously white object gray.
 849   G1BarrierSet::enqueue(obj);
 850 
 851   return obj;
 852 }
 853 
 854 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 855   ResourceMark rm; // For retrieving the thread names in log messages.
 856 
 857   // The structure of this method has a lot of similarities to
 858   // attempt_allocation_slow(). The reason these two were not merged
 859   // into a single one is that such a method would require several "if
 860   // allocation is not humongous do this, otherwise do that"
 861   // conditional paths which would obscure its flow. In fact, an early
 862   // version of this code did use a unified method which was harder to
 863   // follow and, as a result, it had subtle bugs that were hard to
 864   // track down. So keeping these two methods separate allows each to
 865   // be more readable. It will be good to keep these two in sync as
 866   // much as possible.
 867 
 868   assert_heap_not_locked_and_not_at_safepoint();
 869   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 870          "should only be called for humongous allocations");
 871 
 872   // Humongous objects can exhaust the heap quickly, so we should check if we
 873   // need to start a marking cycle at each humongous object allocation. We do
 874   // the check before we do the actual allocation. The reason for doing it
 875   // before the allocation is that we avoid having to keep track of the newly
 876   // allocated memory while we do a GC.
 877   if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
 878                                            word_size)) {
 879     collect(GCCause::_g1_humongous_allocation);
 880   }
 881 
 882   // We will loop until a) we manage to successfully perform the
 883   // allocation or b) we successfully schedule a collection which
 884   // fails to perform the allocation. b) is the only case when we'll
 885   // return NULL.
 886   HeapWord* result = NULL;
 887   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 888     bool should_try_gc;
 889     uint gc_count_before;
 890 
 891 
 892     {
 893       MutexLocker x(Heap_lock);
 894 
 895       // Given that humongous objects are not allocated in young
 896       // regions, we'll first try to do the allocation without doing a
 897       // collection hoping that there's enough space in the heap.
 898       result = humongous_obj_allocate(word_size);
 899       if (result != NULL) {
 900         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 901         policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 902         return result;
 903       }
 904 
 905       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 906       // the GCLocker initiated GC has been performed and then retry. This includes
 907       // the case when the GC Locker is not active but has not been performed.
 908       should_try_gc = !GCLocker::needs_gc();
 909       // Read the GC count while still holding the Heap_lock.
 910       gc_count_before = total_collections();
 911     }
 912 
 913     if (should_try_gc) {
 914       bool succeeded;
 915       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 916                                    GCCause::_g1_humongous_allocation);
 917       if (result != NULL) {
 918         assert(succeeded, "only way to get back a non-NULL result");
 919         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 920                              Thread::current()->name(), p2i(result));
 921         return result;
 922       }
 923 
 924       if (succeeded) {
 925         // We successfully scheduled a collection which failed to allocate. No
 926         // point in trying to allocate further. We'll just return NULL.
 927         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 928                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 929         return NULL;
 930       }
 931       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 932                            Thread::current()->name(), word_size);
 933     } else {
 934       // Failed to schedule a collection.
 935       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 936         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 937                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 938         return NULL;
 939       }
 940       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 941       // The GCLocker is either active or the GCLocker initiated
 942       // GC has not yet been performed. Stall until it is and
 943       // then retry the allocation.
 944       GCLocker::stall_until_clear();
 945       gclocker_retry_count += 1;
 946     }
 947 
 948 
 949     // We can reach here if we were unsuccessful in scheduling a
 950     // collection (because another thread beat us to it) or if we were
 951     // stalled due to the GC locker. In either can we should retry the
 952     // allocation attempt in case another thread successfully
 953     // performed a collection and reclaimed enough space.
 954     // Humongous object allocation always needs a lock, so we wait for the retry
 955     // in the next iteration of the loop, unlike for the regular iteration case.
 956     // Give a warning if we seem to be looping forever.
 957 
 958     if ((QueuedAllocationWarningCount > 0) &&
 959         (try_count % QueuedAllocationWarningCount == 0)) {
 960       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 961                              Thread::current()->name(), try_count, word_size);
 962     }
 963   }
 964 
 965   ShouldNotReachHere();
 966   return NULL;
 967 }
 968 
 969 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 970                                                            bool expect_null_mutator_alloc_region) {
 971   assert_at_safepoint_on_vm_thread();
 972   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 973          "the current alloc region was unexpectedly found to be non-NULL");
 974 
 975   if (!is_humongous(word_size)) {
 976     return _allocator->attempt_allocation_locked(word_size);
 977   } else {
 978     HeapWord* result = humongous_obj_allocate(word_size);
 979     if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
 980       collector_state()->set_initiate_conc_mark_if_possible(true);
 981     }
 982     return result;
 983   }
 984 
 985   ShouldNotReachHere();
 986 }
 987 
 988 class PostCompactionPrinterClosure: public HeapRegionClosure {
 989 private:
 990   G1HRPrinter* _hr_printer;
 991 public:
 992   bool do_heap_region(HeapRegion* hr) {
 993     assert(!hr->is_young(), "not expecting to find young regions");
 994     _hr_printer->post_compaction(hr);
 995     return false;
 996   }
 997 
 998   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 999     : _hr_printer(hr_printer) { }
1000 };
1001 
1002 void G1CollectedHeap::print_hrm_post_compaction() {
1003   if (_hr_printer.is_active()) {
1004     PostCompactionPrinterClosure cl(hr_printer());
1005     heap_region_iterate(&cl);
1006   }
1007 }
1008 
1009 void G1CollectedHeap::abort_concurrent_cycle() {
1010   // If we start the compaction before the CM threads finish
1011   // scanning the root regions we might trip them over as we'll
1012   // be moving objects / updating references. So let's wait until
1013   // they are done. By telling them to abort, they should complete
1014   // early.
1015   _cm->root_regions()->abort();
1016   _cm->root_regions()->wait_until_scan_finished();
1017 
1018   // Disable discovery and empty the discovered lists
1019   // for the CM ref processor.
1020   _ref_processor_cm->disable_discovery();
1021   _ref_processor_cm->abandon_partial_discovery();
1022   _ref_processor_cm->verify_no_references_recorded();
1023 
1024   // Abandon current iterations of concurrent marking and concurrent
1025   // refinement, if any are in progress.
1026   concurrent_mark()->concurrent_cycle_abort();
1027 }
1028 
1029 void G1CollectedHeap::prepare_heap_for_full_collection() {
1030   // Make sure we'll choose a new allocation region afterwards.
1031   _allocator->release_mutator_alloc_regions();
1032   _allocator->abandon_gc_alloc_regions();
1033 
1034   // We may have added regions to the current incremental collection
1035   // set between the last GC or pause and now. We need to clear the
1036   // incremental collection set and then start rebuilding it afresh
1037   // after this full GC.
1038   abandon_collection_set(collection_set());
1039 
1040   tear_down_region_sets(false /* free_list_only */);
1041 
1042   hrm()->prepare_for_full_collection_start();
1043 }
1044 
1045 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1046   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1047   assert_used_and_recalculate_used_equal(this);
1048   _verifier->verify_region_sets_optional();
1049   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1050   _verifier->check_bitmaps("Full GC Start");
1051 }
1052 
1053 void G1CollectedHeap::prepare_heap_for_mutators() {
1054   hrm()->prepare_for_full_collection_end();
1055 
1056   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1057   ClassLoaderDataGraph::purge();
1058   MetaspaceUtils::verify_metrics();
1059 
1060   // Prepare heap for normal collections.
1061   assert(num_free_regions() == 0, "we should not have added any free regions");
1062   rebuild_region_sets(false /* free_list_only */);
1063   abort_refinement();
1064   resize_heap_if_necessary();
1065 
1066   // Rebuild the strong code root lists for each region
1067   rebuild_strong_code_roots();
1068 
1069   // Purge code root memory
1070   purge_code_root_memory();
1071 
1072   // Start a new incremental collection set for the next pause
1073   start_new_collection_set();
1074 
1075   _allocator->init_mutator_alloc_regions();
1076 
1077   // Post collection state updates.
1078   MetaspaceGC::compute_new_size();
1079 }
1080 
1081 void G1CollectedHeap::abort_refinement() {
1082   if (_hot_card_cache->use_cache()) {
1083     _hot_card_cache->reset_hot_cache();
1084   }
1085 
1086   // Discard all remembered set updates.
1087   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1088   assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1089          "DCQS should be empty");
1090 }
1091 
1092 void G1CollectedHeap::verify_after_full_collection() {
1093   _hrm->verify_optional();
1094   _verifier->verify_region_sets_optional();
1095   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1096   // Clear the previous marking bitmap, if needed for bitmap verification.
1097   // Note we cannot do this when we clear the next marking bitmap in
1098   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1099   // objects marked during a full GC against the previous bitmap.
1100   // But we need to clear it before calling check_bitmaps below since
1101   // the full GC has compacted objects and updated TAMS but not updated
1102   // the prev bitmap.
1103   if (G1VerifyBitmaps) {
1104     GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1105     _cm->clear_prev_bitmap(workers());
1106   }
1107   // This call implicitly verifies that the next bitmap is clear after Full GC.
1108   _verifier->check_bitmaps("Full GC End");
1109 
1110   // At this point there should be no regions in the
1111   // entire heap tagged as young.
1112   assert(check_young_list_empty(), "young list should be empty at this point");
1113 
1114   // Note: since we've just done a full GC, concurrent
1115   // marking is no longer active. Therefore we need not
1116   // re-enable reference discovery for the CM ref processor.
1117   // That will be done at the start of the next marking cycle.
1118   // We also know that the STW processor should no longer
1119   // discover any new references.
1120   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1121   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1122   _ref_processor_stw->verify_no_references_recorded();
1123   _ref_processor_cm->verify_no_references_recorded();
1124 }
1125 
1126 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1127   // Post collection logging.
1128   // We should do this after we potentially resize the heap so
1129   // that all the COMMIT / UNCOMMIT events are generated before
1130   // the compaction events.
1131   print_hrm_post_compaction();
1132   heap_transition->print();
1133   print_heap_after_gc();
1134   print_heap_regions();
1135 #ifdef TRACESPINNING
1136   ParallelTaskTerminator::print_termination_counts();
1137 #endif
1138 }
1139 
1140 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1141                                          bool clear_all_soft_refs) {
1142   assert_at_safepoint_on_vm_thread();
1143 
1144   if (GCLocker::check_active_before_gc()) {
1145     // Full GC was not completed.
1146     return false;
1147   }
1148 
1149   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1150       soft_ref_policy()->should_clear_all_soft_refs();
1151 
1152   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1153   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1154 
1155   collector.prepare_collection();
1156   collector.collect();
1157   collector.complete_collection();
1158 
1159   // Full collection was successfully completed.
1160   return true;
1161 }
1162 
1163 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1164   // Currently, there is no facility in the do_full_collection(bool) API to notify
1165   // the caller that the collection did not succeed (e.g., because it was locked
1166   // out by the GC locker). So, right now, we'll ignore the return value.
1167   bool dummy = do_full_collection(true,                /* explicit_gc */
1168                                   clear_all_soft_refs);
1169 }
1170 
1171 void G1CollectedHeap::resize_heap_if_necessary() {
1172   assert_at_safepoint_on_vm_thread();
1173 
1174   // Capacity, free and used after the GC counted as full regions to
1175   // include the waste in the following calculations.
1176   const size_t capacity_after_gc = capacity();
1177   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1178 
1179   // This is enforced in arguments.cpp.
1180   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1181          "otherwise the code below doesn't make sense");
1182 
1183   // We don't have floating point command-line arguments
1184   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1185   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1186   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1187   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1188 
1189   // We have to be careful here as these two calculations can overflow
1190   // 32-bit size_t's.
1191   double used_after_gc_d = (double) used_after_gc;
1192   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1193   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1194 
1195   // Let's make sure that they are both under the max heap size, which
1196   // by default will make them fit into a size_t.
1197   double desired_capacity_upper_bound = (double) MaxHeapSize;
1198   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1199                                     desired_capacity_upper_bound);
1200   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1201                                     desired_capacity_upper_bound);
1202 
1203   // We can now safely turn them into size_t's.
1204   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1205   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1206 
1207   // This assert only makes sense here, before we adjust them
1208   // with respect to the min and max heap size.
1209   assert(minimum_desired_capacity <= maximum_desired_capacity,
1210          "minimum_desired_capacity = " SIZE_FORMAT ", "
1211          "maximum_desired_capacity = " SIZE_FORMAT,
1212          minimum_desired_capacity, maximum_desired_capacity);
1213 
1214   // Should not be greater than the heap max size. No need to adjust
1215   // it with respect to the heap min size as it's a lower bound (i.e.,
1216   // we'll try to make the capacity larger than it, not smaller).
1217   minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1218   // Should not be less than the heap min size. No need to adjust it
1219   // with respect to the heap max size as it's an upper bound (i.e.,
1220   // we'll try to make the capacity smaller than it, not greater).
1221   maximum_desired_capacity =  MAX2(maximum_desired_capacity, MinHeapSize);
1222 
1223   if (capacity_after_gc < minimum_desired_capacity) {
1224     // Don't expand unless it's significant
1225     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1226 
1227     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1228                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1229                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1230                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1231 
1232     expand(expand_bytes, _workers);
1233 
1234     // No expansion, now see if we want to shrink
1235   } else if (capacity_after_gc > maximum_desired_capacity) {
1236     // Capacity too large, compute shrinking size
1237     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1238 
1239     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1240                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1241                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1242                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1243 
1244     shrink(shrink_bytes);
1245   }
1246 }
1247 
1248 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1249                                                             bool do_gc,
1250                                                             bool clear_all_soft_refs,
1251                                                             bool expect_null_mutator_alloc_region,
1252                                                             bool* gc_succeeded) {
1253   *gc_succeeded = true;
1254   // Let's attempt the allocation first.
1255   HeapWord* result =
1256     attempt_allocation_at_safepoint(word_size,
1257                                     expect_null_mutator_alloc_region);
1258   if (result != NULL) {
1259     return result;
1260   }
1261 
1262   // In a G1 heap, we're supposed to keep allocation from failing by
1263   // incremental pauses.  Therefore, at least for now, we'll favor
1264   // expansion over collection.  (This might change in the future if we can
1265   // do something smarter than full collection to satisfy a failed alloc.)
1266   result = expand_and_allocate(word_size);
1267   if (result != NULL) {
1268     return result;
1269   }
1270 
1271   if (do_gc) {
1272     // Expansion didn't work, we'll try to do a Full GC.
1273     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1274                                        clear_all_soft_refs);
1275   }
1276 
1277   return NULL;
1278 }
1279 
1280 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1281                                                      bool* succeeded) {
1282   assert_at_safepoint_on_vm_thread();
1283 
1284   // Attempts to allocate followed by Full GC.
1285   HeapWord* result =
1286     satisfy_failed_allocation_helper(word_size,
1287                                      true,  /* do_gc */
1288                                      false, /* clear_all_soft_refs */
1289                                      false, /* expect_null_mutator_alloc_region */
1290                                      succeeded);
1291 
1292   if (result != NULL || !*succeeded) {
1293     return result;
1294   }
1295 
1296   // Attempts to allocate followed by Full GC that will collect all soft references.
1297   result = satisfy_failed_allocation_helper(word_size,
1298                                             true, /* do_gc */
1299                                             true, /* clear_all_soft_refs */
1300                                             true, /* expect_null_mutator_alloc_region */
1301                                             succeeded);
1302 
1303   if (result != NULL || !*succeeded) {
1304     return result;
1305   }
1306 
1307   // Attempts to allocate, no GC
1308   result = satisfy_failed_allocation_helper(word_size,
1309                                             false, /* do_gc */
1310                                             false, /* clear_all_soft_refs */
1311                                             true,  /* expect_null_mutator_alloc_region */
1312                                             succeeded);
1313 
1314   if (result != NULL) {
1315     return result;
1316   }
1317 
1318   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1319          "Flag should have been handled and cleared prior to this point");
1320 
1321   // What else?  We might try synchronous finalization later.  If the total
1322   // space available is large enough for the allocation, then a more
1323   // complete compaction phase than we've tried so far might be
1324   // appropriate.
1325   return NULL;
1326 }
1327 
1328 // Attempting to expand the heap sufficiently
1329 // to support an allocation of the given "word_size".  If
1330 // successful, perform the allocation and return the address of the
1331 // allocated block, or else "NULL".
1332 
1333 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1334   assert_at_safepoint_on_vm_thread();
1335 
1336   _verifier->verify_region_sets_optional();
1337 
1338   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1339   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1340                             word_size * HeapWordSize);
1341 
1342 
1343   if (expand(expand_bytes, _workers)) {
1344     _hrm->verify_optional();
1345     _verifier->verify_region_sets_optional();
1346     return attempt_allocation_at_safepoint(word_size,
1347                                            false /* expect_null_mutator_alloc_region */);
1348   }
1349   return NULL;
1350 }
1351 
1352 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1353   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1354   aligned_expand_bytes = align_up(aligned_expand_bytes,
1355                                        HeapRegion::GrainBytes);
1356 
1357   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1358                             expand_bytes, aligned_expand_bytes);
1359 
1360   if (is_maximal_no_gc()) {
1361     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1362     return false;
1363   }
1364 
1365   double expand_heap_start_time_sec = os::elapsedTime();
1366   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1367   assert(regions_to_expand > 0, "Must expand by at least one region");
1368 
1369   uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1370   if (expand_time_ms != NULL) {
1371     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1372   }
1373 
1374   if (expanded_by > 0) {
1375     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1376     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1377     policy()->record_new_heap_size(num_regions());
1378   } else {
1379     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1380 
1381     // The expansion of the virtual storage space was unsuccessful.
1382     // Let's see if it was because we ran out of swap.
1383     if (G1ExitOnExpansionFailure &&
1384         _hrm->available() >= regions_to_expand) {
1385       // We had head room...
1386       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1387     }
1388   }
1389   return regions_to_expand > 0;
1390 }
1391 
1392 bool G1CollectedHeap::expand_single_region(uint node_index) {
1393   uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1394 
1395   if (expanded_by == 0) {
1396     assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1397     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1398     return false;
1399   }
1400 
1401   policy()->record_new_heap_size(num_regions());
1402   return true;
1403 }
1404 
1405 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1406   size_t aligned_shrink_bytes =
1407     ReservedSpace::page_align_size_down(shrink_bytes);
1408   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1409                                          HeapRegion::GrainBytes);
1410   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1411 
1412   uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1413   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1414 
1415   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",
1416                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1417   if (num_regions_removed > 0) {
1418     policy()->record_new_heap_size(num_regions());
1419   } else {
1420     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1421   }
1422 }
1423 
1424 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1425   _verifier->verify_region_sets_optional();
1426 
1427   // We should only reach here at the end of a Full GC or during Remark which
1428   // means we should not not be holding to any GC alloc regions. The method
1429   // below will make sure of that and do any remaining clean up.
1430   _allocator->abandon_gc_alloc_regions();
1431 
1432   // Instead of tearing down / rebuilding the free lists here, we
1433   // could instead use the remove_all_pending() method on free_list to
1434   // remove only the ones that we need to remove.
1435   tear_down_region_sets(true /* free_list_only */);
1436   shrink_helper(shrink_bytes);
1437   rebuild_region_sets(true /* free_list_only */);
1438 
1439   _hrm->verify_optional();
1440   _verifier->verify_region_sets_optional();
1441 }
1442 
1443 class OldRegionSetChecker : public HeapRegionSetChecker {
1444 public:
1445   void check_mt_safety() {
1446     // Master Old Set MT safety protocol:
1447     // (a) If we're at a safepoint, operations on the master old set
1448     // should be invoked:
1449     // - by the VM thread (which will serialize them), or
1450     // - by the GC workers while holding the FreeList_lock, if we're
1451     //   at a safepoint for an evacuation pause (this lock is taken
1452     //   anyway when an GC alloc region is retired so that a new one
1453     //   is allocated from the free list), or
1454     // - by the GC workers while holding the OldSets_lock, if we're at a
1455     //   safepoint for a cleanup pause.
1456     // (b) If we're not at a safepoint, operations on the master old set
1457     // should be invoked while holding the Heap_lock.
1458 
1459     if (SafepointSynchronize::is_at_safepoint()) {
1460       guarantee(Thread::current()->is_VM_thread() ||
1461                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1462                 "master old set MT safety protocol at a safepoint");
1463     } else {
1464       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1465     }
1466   }
1467   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1468   const char* get_description() { return "Old Regions"; }
1469 };
1470 
1471 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1472 public:
1473   void check_mt_safety() {
1474     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1475               "May only change archive regions during initialization or safepoint.");
1476   }
1477   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1478   const char* get_description() { return "Archive Regions"; }
1479 };
1480 
1481 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1482 public:
1483   void check_mt_safety() {
1484     // Humongous Set MT safety protocol:
1485     // (a) If we're at a safepoint, operations on the master humongous
1486     // set should be invoked by either the VM thread (which will
1487     // serialize them) or by the GC workers while holding the
1488     // OldSets_lock.
1489     // (b) If we're not at a safepoint, operations on the master
1490     // humongous set should be invoked while holding the Heap_lock.
1491 
1492     if (SafepointSynchronize::is_at_safepoint()) {
1493       guarantee(Thread::current()->is_VM_thread() ||
1494                 OldSets_lock->owned_by_self(),
1495                 "master humongous set MT safety protocol at a safepoint");
1496     } else {
1497       guarantee(Heap_lock->owned_by_self(),
1498                 "master humongous set MT safety protocol outside a safepoint");
1499     }
1500   }
1501   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1502   const char* get_description() { return "Humongous Regions"; }
1503 };
1504 
1505 G1CollectedHeap::G1CollectedHeap() :
1506   CollectedHeap(),
1507   _young_gen_sampling_thread(NULL),
1508   _workers(NULL),
1509   _card_table(NULL),
1510   _soft_ref_policy(),
1511   _old_set("Old Region Set", new OldRegionSetChecker()),
1512   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1513   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1514   _bot(NULL),
1515   _listener(),
1516   _numa(G1NUMA::create()),
1517   _hrm(NULL),
1518   _allocator(NULL),
1519   _verifier(NULL),
1520   _summary_bytes_used(0),
1521   _archive_allocator(NULL),
1522   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1523   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1524   _expand_heap_after_alloc_failure(true),
1525   _g1mm(NULL),
1526   _humongous_reclaim_candidates(),
1527   _has_humongous_reclaim_candidates(false),
1528   _hr_printer(),
1529   _collector_state(),
1530   _old_marking_cycles_started(0),
1531   _old_marking_cycles_completed(0),
1532   _eden(),
1533   _survivor(),
1534   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1535   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1536   _policy(G1Policy::create_policy(_gc_timer_stw)),
1537   _heap_sizing_policy(NULL),
1538   _collection_set(this, _policy),
1539   _hot_card_cache(NULL),
1540   _rem_set(NULL),
1541   _cm(NULL),
1542   _cm_thread(NULL),
1543   _cr(NULL),
1544   _task_queues(NULL),
1545   _evacuation_failed(false),
1546   _evacuation_failed_info_array(NULL),
1547   _preserved_marks_set(true /* in_c_heap */),
1548 #ifndef PRODUCT
1549   _evacuation_failure_alot_for_current_gc(false),
1550   _evacuation_failure_alot_gc_number(0),
1551   _evacuation_failure_alot_count(0),
1552 #endif
1553   _ref_processor_stw(NULL),
1554   _is_alive_closure_stw(this),
1555   _is_subject_to_discovery_stw(this),
1556   _ref_processor_cm(NULL),
1557   _is_alive_closure_cm(this),
1558   _is_subject_to_discovery_cm(this),
1559   _region_attr() {
1560 
1561   _verifier = new G1HeapVerifier(this);
1562 
1563   _allocator = new G1Allocator(this);
1564 
1565   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1566 
1567   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1568 
1569   // Override the default _filler_array_max_size so that no humongous filler
1570   // objects are created.
1571   _filler_array_max_size = _humongous_object_threshold_in_words;
1572 
1573   uint n_queues = ParallelGCThreads;
1574   _task_queues = new RefToScanQueueSet(n_queues);
1575 
1576   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1577 
1578   for (uint i = 0; i < n_queues; i++) {
1579     RefToScanQueue* q = new RefToScanQueue();
1580     q->initialize();
1581     _task_queues->register_queue(i, q);
1582     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1583   }
1584 
1585   // Initialize the G1EvacuationFailureALot counters and flags.
1586   NOT_PRODUCT(reset_evacuation_should_fail();)
1587   _gc_tracer_stw->initialize();
1588 
1589   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1590 }
1591 
1592 static size_t actual_reserved_page_size(ReservedSpace rs) {
1593   size_t page_size = os::vm_page_size();
1594   if (UseLargePages) {
1595     // There are two ways to manage large page memory.
1596     // 1. OS supports committing large page memory.
1597     // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1598     //    And ReservedSpace calls it 'special'. If we failed to set 'special',
1599     //    we reserved memory without large page.
1600     if (os::can_commit_large_page_memory() || rs.special()) {
1601       // An alignment at ReservedSpace comes from preferred page size or
1602       // heap alignment, and if the alignment came from heap alignment, it could be
1603       // larger than large pages size. So need to cap with the large page size.
1604       page_size = MIN2(rs.alignment(), os::large_page_size());
1605     }
1606   }
1607 
1608   return page_size;
1609 }
1610 
1611 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1612                                                                  size_t size,
1613                                                                  size_t translation_factor) {
1614   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1615   // Allocate a new reserved space, preferring to use large pages.
1616   ReservedSpace rs(size, preferred_page_size);
1617   size_t page_size = actual_reserved_page_size(rs);
1618   G1RegionToSpaceMapper* result  =
1619     G1RegionToSpaceMapper::create_mapper(rs,
1620                                          size,
1621                                          page_size,
1622                                          HeapRegion::GrainBytes,
1623                                          translation_factor,
1624                                          mtGC);
1625 
1626   os::trace_page_sizes_for_requested_size(description,
1627                                           size,
1628                                           preferred_page_size,
1629                                           page_size,
1630                                           rs.base(),
1631                                           rs.size());
1632 
1633   return result;
1634 }
1635 
1636 jint G1CollectedHeap::initialize_concurrent_refinement() {
1637   jint ecode = JNI_OK;
1638   _cr = G1ConcurrentRefine::create(&ecode);
1639   return ecode;
1640 }
1641 
1642 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1643   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1644   if (_young_gen_sampling_thread->osthread() == NULL) {
1645     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1646     return JNI_ENOMEM;
1647   }
1648   return JNI_OK;
1649 }
1650 
1651 jint G1CollectedHeap::initialize() {
1652 
1653   // Necessary to satisfy locking discipline assertions.
1654 
1655   MutexLocker x(Heap_lock);
1656 
1657   // While there are no constraints in the GC code that HeapWordSize
1658   // be any particular value, there are multiple other areas in the
1659   // system which believe this to be true (e.g. oop->object_size in some
1660   // cases incorrectly returns the size in wordSize units rather than
1661   // HeapWordSize).
1662   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1663 
1664   size_t init_byte_size = InitialHeapSize;
1665   size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1666 
1667   // Ensure that the sizes are properly aligned.
1668   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1669   Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1670   Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1671 
1672   // Reserve the maximum.
1673 
1674   // When compressed oops are enabled, the preferred heap base
1675   // is calculated by subtracting the requested size from the
1676   // 32Gb boundary and using the result as the base address for
1677   // heap reservation. If the requested size is not aligned to
1678   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1679   // into the ReservedHeapSpace constructor) then the actual
1680   // base of the reserved heap may end up differing from the
1681   // address that was requested (i.e. the preferred heap base).
1682   // If this happens then we could end up using a non-optimal
1683   // compressed oops mode.
1684 
1685   ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1686                                                      HeapAlignment);
1687 
1688   initialize_reserved_region(heap_rs);
1689 
1690   // Create the barrier set for the entire reserved region.
1691   G1CardTable* ct = new G1CardTable(heap_rs.region());
1692   ct->initialize();
1693   G1BarrierSet* bs = new G1BarrierSet(ct);
1694   bs->initialize();
1695   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1696   BarrierSet::set_barrier_set(bs);
1697   _card_table = ct;
1698 
1699   {
1700     G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1701     satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1702     satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1703   }
1704 
1705   // Create the hot card cache.
1706   _hot_card_cache = new G1HotCardCache(this);
1707 
1708   // Carve out the G1 part of the heap.
1709   ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1710   size_t page_size = actual_reserved_page_size(heap_rs);
1711   G1RegionToSpaceMapper* heap_storage =
1712     G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1713                                               g1_rs.size(),
1714                                               page_size,
1715                                               HeapRegion::GrainBytes,
1716                                               1,
1717                                               mtJavaHeap);
1718   if(heap_storage == NULL) {
1719     vm_shutdown_during_initialization("Could not initialize G1 heap");
1720     return JNI_ERR;
1721   }
1722 
1723   os::trace_page_sizes("Heap",
1724                        MinHeapSize,
1725                        reserved_byte_size,
1726                        page_size,
1727                        heap_rs.base(),
1728                        heap_rs.size());
1729   heap_storage->set_mapping_changed_listener(&_listener);
1730 
1731   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1732   G1RegionToSpaceMapper* bot_storage =
1733     create_aux_memory_mapper("Block Offset Table",
1734                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1735                              G1BlockOffsetTable::heap_map_factor());
1736 
1737   G1RegionToSpaceMapper* cardtable_storage =
1738     create_aux_memory_mapper("Card Table",
1739                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1740                              G1CardTable::heap_map_factor());
1741 
1742   G1RegionToSpaceMapper* card_counts_storage =
1743     create_aux_memory_mapper("Card Counts Table",
1744                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1745                              G1CardCounts::heap_map_factor());
1746 
1747   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1748   G1RegionToSpaceMapper* prev_bitmap_storage =
1749     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1750   G1RegionToSpaceMapper* next_bitmap_storage =
1751     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1752 
1753   _hrm = HeapRegionManager::create_manager(this);
1754 
1755   _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1756   _card_table->initialize(cardtable_storage);
1757 
1758   // Do later initialization work for concurrent refinement.
1759   _hot_card_cache->initialize(card_counts_storage);
1760 
1761   // 6843694 - ensure that the maximum region index can fit
1762   // in the remembered set structures.
1763   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1764   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1765 
1766   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1767   // start within the first card.
1768   guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1769   // Also create a G1 rem set.
1770   _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1771   _rem_set->initialize(max_reserved_capacity(), max_regions());
1772 
1773   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1774   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1775   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1776             "too many cards per region");
1777 
1778   FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1779 
1780   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1781 
1782   {
1783     HeapWord* start = _hrm->reserved().start();
1784     HeapWord* end = _hrm->reserved().end();
1785     size_t granularity = HeapRegion::GrainBytes;
1786 
1787     _region_attr.initialize(start, end, granularity);
1788     _humongous_reclaim_candidates.initialize(start, end, granularity);
1789   }
1790 
1791   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1792                           true /* are_GC_task_threads */,
1793                           false /* are_ConcurrentGC_threads */);
1794   if (_workers == NULL) {
1795     return JNI_ENOMEM;
1796   }
1797   _workers->initialize_workers();
1798 
1799   _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1800 
1801   // Create the G1ConcurrentMark data structure and thread.
1802   // (Must do this late, so that "max_regions" is defined.)
1803   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1804   if (_cm == NULL || !_cm->completed_initialization()) {
1805     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1806     return JNI_ENOMEM;
1807   }
1808   _cm_thread = _cm->cm_thread();
1809 
1810   // Now expand into the initial heap size.
1811   if (!expand(init_byte_size, _workers)) {
1812     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1813     return JNI_ENOMEM;
1814   }
1815 
1816   // Perform any initialization actions delegated to the policy.
1817   policy()->init(this, &_collection_set);
1818 
1819   jint ecode = initialize_concurrent_refinement();
1820   if (ecode != JNI_OK) {
1821     return ecode;
1822   }
1823 
1824   ecode = initialize_young_gen_sampling_thread();
1825   if (ecode != JNI_OK) {
1826     return ecode;
1827   }
1828 
1829   {
1830     G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1831     dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1832     dcqs.set_max_cards(concurrent_refine()->red_zone());
1833   }
1834 
1835   // Here we allocate the dummy HeapRegion that is required by the
1836   // G1AllocRegion class.
1837   HeapRegion* dummy_region = _hrm->get_dummy_region();
1838 
1839   // We'll re-use the same region whether the alloc region will
1840   // require BOT updates or not and, if it doesn't, then a non-young
1841   // region will complain that it cannot support allocations without
1842   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1843   dummy_region->set_eden();
1844   // Make sure it's full.
1845   dummy_region->set_top(dummy_region->end());
1846   G1AllocRegion::setup(this, dummy_region);
1847 
1848   _allocator->init_mutator_alloc_regions();
1849 
1850   // Do create of the monitoring and management support so that
1851   // values in the heap have been properly initialized.
1852   _g1mm = new G1MonitoringSupport(this);
1853 
1854   G1StringDedup::initialize();
1855 
1856   _preserved_marks_set.init(ParallelGCThreads);
1857 
1858   _collection_set.initialize(max_regions());
1859 
1860   return JNI_OK;
1861 }
1862 
1863 void G1CollectedHeap::stop() {
1864   // Stop all concurrent threads. We do this to make sure these threads
1865   // do not continue to execute and access resources (e.g. logging)
1866   // that are destroyed during shutdown.
1867   _cr->stop();
1868   _young_gen_sampling_thread->stop();
1869   _cm_thread->stop();
1870   if (G1StringDedup::is_enabled()) {
1871     G1StringDedup::stop();
1872   }
1873 }
1874 
1875 void G1CollectedHeap::safepoint_synchronize_begin() {
1876   SuspendibleThreadSet::synchronize();
1877 }
1878 
1879 void G1CollectedHeap::safepoint_synchronize_end() {
1880   SuspendibleThreadSet::desynchronize();
1881 }
1882 
1883 void G1CollectedHeap::post_initialize() {
1884   CollectedHeap::post_initialize();
1885   ref_processing_init();
1886 }
1887 
1888 void G1CollectedHeap::ref_processing_init() {
1889   // Reference processing in G1 currently works as follows:
1890   //
1891   // * There are two reference processor instances. One is
1892   //   used to record and process discovered references
1893   //   during concurrent marking; the other is used to
1894   //   record and process references during STW pauses
1895   //   (both full and incremental).
1896   // * Both ref processors need to 'span' the entire heap as
1897   //   the regions in the collection set may be dotted around.
1898   //
1899   // * For the concurrent marking ref processor:
1900   //   * Reference discovery is enabled at initial marking.
1901   //   * Reference discovery is disabled and the discovered
1902   //     references processed etc during remarking.
1903   //   * Reference discovery is MT (see below).
1904   //   * Reference discovery requires a barrier (see below).
1905   //   * Reference processing may or may not be MT
1906   //     (depending on the value of ParallelRefProcEnabled
1907   //     and ParallelGCThreads).
1908   //   * A full GC disables reference discovery by the CM
1909   //     ref processor and abandons any entries on it's
1910   //     discovered lists.
1911   //
1912   // * For the STW processor:
1913   //   * Non MT discovery is enabled at the start of a full GC.
1914   //   * Processing and enqueueing during a full GC is non-MT.
1915   //   * During a full GC, references are processed after marking.
1916   //
1917   //   * Discovery (may or may not be MT) is enabled at the start
1918   //     of an incremental evacuation pause.
1919   //   * References are processed near the end of a STW evacuation pause.
1920   //   * For both types of GC:
1921   //     * Discovery is atomic - i.e. not concurrent.
1922   //     * Reference discovery will not need a barrier.
1923 
1924   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1925 
1926   // Concurrent Mark ref processor
1927   _ref_processor_cm =
1928     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1929                            mt_processing,                                  // mt processing
1930                            ParallelGCThreads,                              // degree of mt processing
1931                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1932                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1933                            false,                                          // Reference discovery is not atomic
1934                            &_is_alive_closure_cm,                          // is alive closure
1935                            true);                                          // allow changes to number of processing threads
1936 
1937   // STW ref processor
1938   _ref_processor_stw =
1939     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1940                            mt_processing,                        // mt processing
1941                            ParallelGCThreads,                    // degree of mt processing
1942                            (ParallelGCThreads > 1),              // mt discovery
1943                            ParallelGCThreads,                    // degree of mt discovery
1944                            true,                                 // Reference discovery is atomic
1945                            &_is_alive_closure_stw,               // is alive closure
1946                            true);                                // allow changes to number of processing threads
1947 }
1948 
1949 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1950   return &_soft_ref_policy;
1951 }
1952 
1953 size_t G1CollectedHeap::capacity() const {
1954   return _hrm->length() * HeapRegion::GrainBytes;
1955 }
1956 
1957 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1958   return _hrm->total_free_bytes();
1959 }
1960 
1961 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1962   _hot_card_cache->drain(cl, worker_id);
1963 }
1964 
1965 // Computes the sum of the storage used by the various regions.
1966 size_t G1CollectedHeap::used() const {
1967   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1968   if (_archive_allocator != NULL) {
1969     result += _archive_allocator->used();
1970   }
1971   return result;
1972 }
1973 
1974 size_t G1CollectedHeap::used_unlocked() const {
1975   return _summary_bytes_used;
1976 }
1977 
1978 class SumUsedClosure: public HeapRegionClosure {
1979   size_t _used;
1980 public:
1981   SumUsedClosure() : _used(0) {}
1982   bool do_heap_region(HeapRegion* r) {
1983     _used += r->used();
1984     return false;
1985   }
1986   size_t result() { return _used; }
1987 };
1988 
1989 size_t G1CollectedHeap::recalculate_used() const {
1990   SumUsedClosure blk;
1991   heap_region_iterate(&blk);
1992   return blk.result();
1993 }
1994 
1995 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1996   switch (cause) {
1997     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1998     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1999     case GCCause::_wb_conc_mark:                        return true;
2000     default :                                           return false;
2001   }
2002 }
2003 
2004 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2005   switch (cause) {
2006     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2007     case GCCause::_g1_humongous_allocation: return true;
2008     case GCCause::_g1_periodic_collection:  return G1PeriodicGCInvokesConcurrent;
2009     default:                                return is_user_requested_concurrent_full_gc(cause);
2010   }
2011 }
2012 
2013 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2014   if(policy()->force_upgrade_to_full()) {
2015     return true;
2016   } else if (should_do_concurrent_full_gc(_gc_cause)) {
2017     return false;
2018   } else if (has_regions_left_for_allocation()) {
2019     return false;
2020   } else {
2021     return true;
2022   }
2023 }
2024 
2025 #ifndef PRODUCT
2026 void G1CollectedHeap::allocate_dummy_regions() {
2027   // Let's fill up most of the region
2028   size_t word_size = HeapRegion::GrainWords - 1024;
2029   // And as a result the region we'll allocate will be humongous.
2030   guarantee(is_humongous(word_size), "sanity");
2031 
2032   // _filler_array_max_size is set to humongous object threshold
2033   // but temporarily change it to use CollectedHeap::fill_with_object().
2034   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2035 
2036   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2037     // Let's use the existing mechanism for the allocation
2038     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2039     if (dummy_obj != NULL) {
2040       MemRegion mr(dummy_obj, word_size);
2041       CollectedHeap::fill_with_object(mr);
2042     } else {
2043       // If we can't allocate once, we probably cannot allocate
2044       // again. Let's get out of the loop.
2045       break;
2046     }
2047   }
2048 }
2049 #endif // !PRODUCT
2050 
2051 void G1CollectedHeap::increment_old_marking_cycles_started() {
2052   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2053          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2054          "Wrong marking cycle count (started: %d, completed: %d)",
2055          _old_marking_cycles_started, _old_marking_cycles_completed);
2056 
2057   _old_marking_cycles_started++;
2058 }
2059 
2060 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2061   MonitorLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2062 
2063   // We assume that if concurrent == true, then the caller is a
2064   // concurrent thread that was joined the Suspendible Thread
2065   // Set. If there's ever a cheap way to check this, we should add an
2066   // assert here.
2067 
2068   // Given that this method is called at the end of a Full GC or of a
2069   // concurrent cycle, and those can be nested (i.e., a Full GC can
2070   // interrupt a concurrent cycle), the number of full collections
2071   // completed should be either one (in the case where there was no
2072   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2073   // behind the number of full collections started.
2074 
2075   // This is the case for the inner caller, i.e. a Full GC.
2076   assert(concurrent ||
2077          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2078          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2079          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2080          "is inconsistent with _old_marking_cycles_completed = %u",
2081          _old_marking_cycles_started, _old_marking_cycles_completed);
2082 
2083   // This is the case for the outer caller, i.e. the concurrent cycle.
2084   assert(!concurrent ||
2085          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2086          "for outer caller (concurrent cycle): "
2087          "_old_marking_cycles_started = %u "
2088          "is inconsistent with _old_marking_cycles_completed = %u",
2089          _old_marking_cycles_started, _old_marking_cycles_completed);
2090 
2091   _old_marking_cycles_completed += 1;
2092 
2093   // We need to clear the "in_progress" flag in the CM thread before
2094   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2095   // is set) so that if a waiter requests another System.gc() it doesn't
2096   // incorrectly see that a marking cycle is still in progress.
2097   if (concurrent) {
2098     _cm_thread->set_idle();
2099   }
2100 
2101   // This notify_all() will ensure that a thread that called
2102   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2103   // and it's waiting for a full GC to finish will be woken up. It is
2104   // waiting in VM_G1CollectForAllocation::doit_epilogue().
2105   FullGCCount_lock->notify_all();
2106 }
2107 
2108 void G1CollectedHeap::collect(GCCause::Cause cause) {
2109   try_collect(cause, true);
2110 }
2111 
2112 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) {
2113   assert_heap_not_locked();
2114 
2115   bool gc_succeeded;
2116   bool should_retry_gc;
2117 
2118   do {
2119     should_retry_gc = false;
2120 
2121     uint gc_count_before;
2122     uint old_marking_count_before;
2123     uint full_gc_count_before;
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                                    policy()->max_pause_time_ms());
2143       VMThread::execute(&op);
2144       gc_succeeded = op.gc_succeeded();
2145       if (!gc_succeeded && retry_on_gc_failure) {
2146         if (old_marking_count_before == _old_marking_cycles_started) {
2147           should_retry_gc = op.should_retry_gc();
2148         } else {
2149           // A Full GC happened while we were trying to schedule the
2150           // concurrent cycle. No point in starting a new cycle given
2151           // that the whole heap was collected anyway.
2152         }
2153 
2154         if (should_retry_gc && GCLocker::is_active_and_needs_gc()) {
2155           GCLocker::stall_until_clear();
2156         }
2157       }
2158     } else if (GCLocker::should_discard(cause, gc_count_before)) {
2159       // Return false to be consistent with VMOp failure due to
2160       // another collection slipping in after our gc_count but before
2161       // our request is processed.  _gc_locker collections upgraded by
2162       // GCLockerInvokesConcurrent are handled above and never discarded.
2163       return false;
2164     } else {
2165       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2166           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2167 
2168         // Schedule a standard evacuation pause. We're setting word_size
2169         // to 0 which means that we are not requesting a post-GC allocation.
2170         VM_G1CollectForAllocation op(0,     /* word_size */
2171                                      gc_count_before,
2172                                      cause,
2173                                      false, /* should_initiate_conc_mark */
2174                                      policy()->max_pause_time_ms());
2175         VMThread::execute(&op);
2176         gc_succeeded = op.gc_succeeded();
2177       } else {
2178         // Schedule a Full GC.
2179         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2180         VMThread::execute(&op);
2181         gc_succeeded = op.gc_succeeded();
2182       }
2183     }
2184   } while (should_retry_gc);
2185   return gc_succeeded;
2186 }
2187 
2188 bool G1CollectedHeap::is_in(const void* p) const {
2189   if (_hrm->reserved().contains(p)) {
2190     // Given that we know that p is in the reserved space,
2191     // heap_region_containing() should successfully
2192     // return the containing region.
2193     HeapRegion* hr = heap_region_containing(p);
2194     return hr->is_in(p);
2195   } else {
2196     return false;
2197   }
2198 }
2199 
2200 #ifdef ASSERT
2201 bool G1CollectedHeap::is_in_exact(const void* p) const {
2202   bool contains = reserved_region().contains(p);
2203   bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2204   if (contains && available) {
2205     return true;
2206   } else {
2207     return false;
2208   }
2209 }
2210 #endif
2211 
2212 // Iteration functions.
2213 
2214 // Iterates an ObjectClosure over all objects within a HeapRegion.
2215 
2216 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2217   ObjectClosure* _cl;
2218 public:
2219   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2220   bool do_heap_region(HeapRegion* r) {
2221     if (!r->is_continues_humongous()) {
2222       r->object_iterate(_cl);
2223     }
2224     return false;
2225   }
2226 };
2227 
2228 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2229   IterateObjectClosureRegionClosure blk(cl);
2230   heap_region_iterate(&blk);
2231 }
2232 
2233 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2234   _hrm->iterate(cl);
2235 }
2236 
2237 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2238                                                                  HeapRegionClaimer *hrclaimer,
2239                                                                  uint worker_id) const {
2240   _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2241 }
2242 
2243 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2244                                                          HeapRegionClaimer *hrclaimer) const {
2245   _hrm->par_iterate(cl, hrclaimer, 0);
2246 }
2247 
2248 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2249   _collection_set.iterate(cl);
2250 }
2251 
2252 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2253   _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2254 }
2255 
2256 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2257   HeapRegion* hr = heap_region_containing(addr);
2258   return hr->block_start(addr);
2259 }
2260 
2261 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2262   HeapRegion* hr = heap_region_containing(addr);
2263   return hr->block_is_obj(addr);
2264 }
2265 
2266 bool G1CollectedHeap::supports_tlab_allocation() const {
2267   return true;
2268 }
2269 
2270 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2271   return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2272 }
2273 
2274 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2275   return _eden.length() * HeapRegion::GrainBytes;
2276 }
2277 
2278 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2279 // must be equal to the humongous object limit.
2280 size_t G1CollectedHeap::max_tlab_size() const {
2281   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2282 }
2283 
2284 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2285   return _allocator->unsafe_max_tlab_alloc();
2286 }
2287 
2288 size_t G1CollectedHeap::max_capacity() const {
2289   return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2290 }
2291 
2292 size_t G1CollectedHeap::max_reserved_capacity() const {
2293   return _hrm->max_length() * HeapRegion::GrainBytes;
2294 }
2295 
2296 jlong G1CollectedHeap::millis_since_last_gc() {
2297   // See the notes in GenCollectedHeap::millis_since_last_gc()
2298   // for more information about the implementation.
2299   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2300                   _policy->collection_pause_end_millis();
2301   if (ret_val < 0) {
2302     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2303       ". returning zero instead.", ret_val);
2304     return 0;
2305   }
2306   return ret_val;
2307 }
2308 
2309 void G1CollectedHeap::deduplicate_string(oop str) {
2310   assert(java_lang_String::is_instance(str), "invariant");
2311 
2312   if (G1StringDedup::is_enabled()) {
2313     G1StringDedup::deduplicate(str);
2314   }
2315 }
2316 
2317 void G1CollectedHeap::prepare_for_verify() {
2318   _verifier->prepare_for_verify();
2319 }
2320 
2321 void G1CollectedHeap::verify(VerifyOption vo) {
2322   _verifier->verify(vo);
2323 }
2324 
2325 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2326   return true;
2327 }
2328 
2329 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2330   return _cm_thread->request_concurrent_phase(phase);
2331 }
2332 
2333 bool G1CollectedHeap::is_heterogeneous_heap() const {
2334   return G1Arguments::is_heterogeneous_heap();
2335 }
2336 
2337 class PrintRegionClosure: public HeapRegionClosure {
2338   outputStream* _st;
2339 public:
2340   PrintRegionClosure(outputStream* st) : _st(st) {}
2341   bool do_heap_region(HeapRegion* r) {
2342     r->print_on(_st);
2343     return false;
2344   }
2345 };
2346 
2347 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2348                                        const HeapRegion* hr,
2349                                        const VerifyOption vo) const {
2350   switch (vo) {
2351   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2352   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2353   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2354   default:                            ShouldNotReachHere();
2355   }
2356   return false; // keep some compilers happy
2357 }
2358 
2359 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2360                                        const VerifyOption vo) const {
2361   switch (vo) {
2362   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2363   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2364   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2365   default:                            ShouldNotReachHere();
2366   }
2367   return false; // keep some compilers happy
2368 }
2369 
2370 void G1CollectedHeap::print_heap_regions() const {
2371   LogTarget(Trace, gc, heap, region) lt;
2372   if (lt.is_enabled()) {
2373     LogStream ls(lt);
2374     print_regions_on(&ls);
2375   }
2376 }
2377 
2378 void G1CollectedHeap::print_on(outputStream* st) const {
2379   st->print(" %-20s", "garbage-first heap");
2380   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2381             capacity()/K, used_unlocked()/K);
2382   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2383             p2i(_hrm->reserved().start()),
2384             p2i(_hrm->reserved().end()));
2385   st->cr();
2386   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2387   uint young_regions = young_regions_count();
2388   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2389             (size_t) young_regions * HeapRegion::GrainBytes / K);
2390   uint survivor_regions = survivor_regions_count();
2391   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2392             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2393   st->cr();
2394   if (_numa->is_enabled()) {
2395     uint num_nodes = _numa->num_active_nodes();
2396     st->print("  remaining free region(s) on each NUMA node: ");
2397     const int* node_ids = _numa->node_ids();
2398     for (uint node_index = 0; node_index < num_nodes; node_index++) {
2399       st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index));
2400     }
2401     st->cr();
2402   }
2403   MetaspaceUtils::print_on(st);
2404 }
2405 
2406 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2407   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2408                "HS=humongous(starts), HC=humongous(continues), "
2409                "CS=collection set, F=free, "
2410                "OA=open archive, CA=closed archive, "
2411                "TAMS=top-at-mark-start (previous, next)");
2412   PrintRegionClosure blk(st);
2413   heap_region_iterate(&blk);
2414 }
2415 
2416 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2417   print_on(st);
2418 
2419   // Print the per-region information.
2420   print_regions_on(st);
2421 }
2422 
2423 void G1CollectedHeap::print_on_error(outputStream* st) const {
2424   this->CollectedHeap::print_on_error(st);
2425 
2426   if (_cm != NULL) {
2427     st->cr();
2428     _cm->print_on_error(st);
2429   }
2430 }
2431 
2432 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2433   workers()->print_worker_threads_on(st);
2434   _cm_thread->print_on(st);
2435   st->cr();
2436   _cm->print_worker_threads_on(st);
2437   _cr->print_threads_on(st);
2438   _young_gen_sampling_thread->print_on(st);
2439   if (G1StringDedup::is_enabled()) {
2440     G1StringDedup::print_worker_threads_on(st);
2441   }
2442 }
2443 
2444 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2445   workers()->threads_do(tc);
2446   tc->do_thread(_cm_thread);
2447   _cm->threads_do(tc);
2448   _cr->threads_do(tc);
2449   tc->do_thread(_young_gen_sampling_thread);
2450   if (G1StringDedup::is_enabled()) {
2451     G1StringDedup::threads_do(tc);
2452   }
2453 }
2454 
2455 void G1CollectedHeap::print_tracing_info() const {
2456   rem_set()->print_summary_info();
2457   concurrent_mark()->print_summary_info();
2458 }
2459 
2460 #ifndef PRODUCT
2461 // Helpful for debugging RSet issues.
2462 
2463 class PrintRSetsClosure : public HeapRegionClosure {
2464 private:
2465   const char* _msg;
2466   size_t _occupied_sum;
2467 
2468 public:
2469   bool do_heap_region(HeapRegion* r) {
2470     HeapRegionRemSet* hrrs = r->rem_set();
2471     size_t occupied = hrrs->occupied();
2472     _occupied_sum += occupied;
2473 
2474     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2475     if (occupied == 0) {
2476       tty->print_cr("  RSet is empty");
2477     } else {
2478       hrrs->print();
2479     }
2480     tty->print_cr("----------");
2481     return false;
2482   }
2483 
2484   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2485     tty->cr();
2486     tty->print_cr("========================================");
2487     tty->print_cr("%s", msg);
2488     tty->cr();
2489   }
2490 
2491   ~PrintRSetsClosure() {
2492     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2493     tty->print_cr("========================================");
2494     tty->cr();
2495   }
2496 };
2497 
2498 void G1CollectedHeap::print_cset_rsets() {
2499   PrintRSetsClosure cl("Printing CSet RSets");
2500   collection_set_iterate_all(&cl);
2501 }
2502 
2503 void G1CollectedHeap::print_all_rsets() {
2504   PrintRSetsClosure cl("Printing All RSets");;
2505   heap_region_iterate(&cl);
2506 }
2507 #endif // PRODUCT
2508 
2509 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2510   return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2511 }
2512 
2513 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2514 
2515   size_t eden_used_bytes = _eden.used_bytes();
2516   size_t survivor_used_bytes = _survivor.used_bytes();
2517   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2518 
2519   size_t eden_capacity_bytes =
2520     (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2521 
2522   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2523   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2524                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2525 }
2526 
2527 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2528   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2529                        stats->unused(), stats->used(), stats->region_end_waste(),
2530                        stats->regions_filled(), stats->direct_allocated(),
2531                        stats->failure_used(), stats->failure_waste());
2532 }
2533 
2534 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2535   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2536   gc_tracer->report_gc_heap_summary(when, heap_summary);
2537 
2538   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2539   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2540 }
2541 
2542 G1CollectedHeap* G1CollectedHeap::heap() {
2543   CollectedHeap* heap = Universe::heap();
2544   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2545   assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2546   return (G1CollectedHeap*)heap;
2547 }
2548 
2549 void G1CollectedHeap::gc_prologue(bool full) {
2550   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2551 
2552   // This summary needs to be printed before incrementing total collections.
2553   rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2554 
2555   // Update common counters.
2556   increment_total_collections(full /* full gc */);
2557   if (full || collector_state()->in_initial_mark_gc()) {
2558     increment_old_marking_cycles_started();
2559   }
2560 
2561   // Fill TLAB's and such
2562   double start = os::elapsedTime();
2563   ensure_parsability(true);
2564   phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2565 }
2566 
2567 void G1CollectedHeap::gc_epilogue(bool full) {
2568   // Update common counters.
2569   if (full) {
2570     // Update the number of full collections that have been completed.
2571     increment_old_marking_cycles_completed(false /* concurrent */);
2572   }
2573 
2574   // We are at the end of the GC. Total collections has already been increased.
2575   rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2576 
2577   // FIXME: what is this about?
2578   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2579   // is set.
2580 #if COMPILER2_OR_JVMCI
2581   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2582 #endif
2583 
2584   double start = os::elapsedTime();
2585   resize_all_tlabs();
2586   phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2587 
2588   MemoryService::track_memory_usage();
2589   // We have just completed a GC. Update the soft reference
2590   // policy with the new heap occupancy
2591   Universe::update_heap_info_at_gc();
2592 
2593   // Print NUMA statistics.
2594   _numa->print_statistics();
2595 }
2596 
2597 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2598   LogTarget(Trace, gc, heap, verify) lt;
2599 
2600   if (lt.is_enabled()) {
2601     LogStream ls(lt);
2602     // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2603     NodeIndexCheckClosure cl(desc, _numa, &ls);
2604     heap_region_iterate(&cl);
2605   } 
2606 }
2607 
2608 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2609                                                uint gc_count_before,
2610                                                bool* succeeded,
2611                                                GCCause::Cause gc_cause) {
2612   assert_heap_not_locked_and_not_at_safepoint();
2613   VM_G1CollectForAllocation op(word_size,
2614                                gc_count_before,
2615                                gc_cause,
2616                                false, /* should_initiate_conc_mark */
2617                                policy()->max_pause_time_ms());
2618   VMThread::execute(&op);
2619 
2620   HeapWord* result = op.result();
2621   bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2622   assert(result == NULL || ret_succeeded,
2623          "the result should be NULL if the VM did not succeed");
2624   *succeeded = ret_succeeded;
2625 
2626   assert_heap_not_locked();
2627   return result;
2628 }
2629 
2630 void G1CollectedHeap::do_concurrent_mark() {
2631   MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2632   if (!_cm_thread->in_progress()) {
2633     _cm_thread->set_started();
2634     CGC_lock->notify();
2635   }
2636 }
2637 
2638 size_t G1CollectedHeap::pending_card_num() {
2639   struct CountCardsClosure : public ThreadClosure {
2640     size_t _cards;
2641     CountCardsClosure() : _cards(0) {}
2642     virtual void do_thread(Thread* t) {
2643       _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2644     }
2645   } count_from_threads;
2646   Threads::threads_do(&count_from_threads);
2647 
2648   G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2649   dcqs.verify_num_cards();
2650 
2651   return dcqs.num_cards() + count_from_threads._cards;
2652 }
2653 
2654 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2655   // We don't nominate objects with many remembered set entries, on
2656   // the assumption that such objects are likely still live.
2657   HeapRegionRemSet* rem_set = r->rem_set();
2658 
2659   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2660          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2661          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2662 }
2663 
2664 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure {
2665  private:
2666   size_t _total_humongous;
2667   size_t _candidate_humongous;
2668 
2669   bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2670     assert(region->is_starts_humongous(), "Must start a humongous object");
2671 
2672     oop obj = oop(region->bottom());
2673 
2674     // Dead objects cannot be eager reclaim candidates. Due to class
2675     // unloading it is unsafe to query their classes so we return early.
2676     if (g1h->is_obj_dead(obj, region)) {
2677       return false;
2678     }
2679 
2680     // If we do not have a complete remembered set for the region, then we can
2681     // not be sure that we have all references to it.
2682     if (!region->rem_set()->is_complete()) {
2683       return false;
2684     }
2685     // Candidate selection must satisfy the following constraints
2686     // while concurrent marking is in progress:
2687     //
2688     // * In order to maintain SATB invariants, an object must not be
2689     // reclaimed if it was allocated before the start of marking and
2690     // has not had its references scanned.  Such an object must have
2691     // its references (including type metadata) scanned to ensure no
2692     // live objects are missed by the marking process.  Objects
2693     // allocated after the start of concurrent marking don't need to
2694     // be scanned.
2695     //
2696     // * An object must not be reclaimed if it is on the concurrent
2697     // mark stack.  Objects allocated after the start of concurrent
2698     // marking are never pushed on the mark stack.
2699     //
2700     // Nominating only objects allocated after the start of concurrent
2701     // marking is sufficient to meet both constraints.  This may miss
2702     // some objects that satisfy the constraints, but the marking data
2703     // structures don't support efficiently performing the needed
2704     // additional tests or scrubbing of the mark stack.
2705     //
2706     // However, we presently only nominate is_typeArray() objects.
2707     // A humongous object containing references induces remembered
2708     // set entries on other regions.  In order to reclaim such an
2709     // object, those remembered sets would need to be cleaned up.
2710     //
2711     // We also treat is_typeArray() objects specially, allowing them
2712     // to be reclaimed even if allocated before the start of
2713     // concurrent mark.  For this we rely on mark stack insertion to
2714     // exclude is_typeArray() objects, preventing reclaiming an object
2715     // that is in the mark stack.  We also rely on the metadata for
2716     // such objects to be built-in and so ensured to be kept live.
2717     // Frequent allocation and drop of large binary blobs is an
2718     // important use case for eager reclaim, and this special handling
2719     // may reduce needed headroom.
2720 
2721     return obj->is_typeArray() &&
2722            g1h->is_potential_eager_reclaim_candidate(region);
2723   }
2724 
2725  public:
2726   RegisterRegionsWithRegionAttrTableClosure()
2727   : _total_humongous(0),
2728     _candidate_humongous(0) {
2729   }
2730 
2731   virtual bool do_heap_region(HeapRegion* r) {
2732     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2733 
2734     if (!r->is_starts_humongous()) {
2735       g1h->register_region_with_region_attr(r);
2736       return false;
2737     }
2738 
2739     bool is_candidate = humongous_region_is_candidate(g1h, r);
2740     uint rindex = r->hrm_index();
2741     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2742     if (is_candidate) {
2743       g1h->register_humongous_region_with_region_attr(rindex);
2744       _candidate_humongous++;
2745       // We will later handle the remembered sets of these regions.
2746     } else {
2747       g1h->register_region_with_region_attr(r);
2748     }
2749     _total_humongous++;
2750 
2751     return false;
2752   }
2753 
2754   size_t total_humongous() const { return _total_humongous; }
2755   size_t candidate_humongous() const { return _candidate_humongous; }
2756 };
2757 
2758 void G1CollectedHeap::register_regions_with_region_attr() {
2759   Ticks start = Ticks::now();
2760 
2761   RegisterRegionsWithRegionAttrTableClosure cl;
2762   heap_region_iterate(&cl);
2763 
2764   phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0,
2765                                          cl.total_humongous(),
2766                                          cl.candidate_humongous());
2767   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2768 }
2769 
2770 #ifndef PRODUCT
2771 void G1CollectedHeap::verify_region_attr_remset_update() {
2772   class VerifyRegionAttrRemSet : public HeapRegionClosure {
2773   public:
2774     virtual bool do_heap_region(HeapRegion* r) {
2775       G1CollectedHeap* g1h = G1CollectedHeap::heap();
2776       bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2777       assert(r->rem_set()->is_tracked() == needs_remset_update,
2778              "Region %u remset tracking status (%s) different to region attribute (%s)",
2779              r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2780       return false;
2781     }
2782   } cl;
2783   heap_region_iterate(&cl);
2784 }
2785 #endif
2786 
2787 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2788   public:
2789     bool do_heap_region(HeapRegion* hr) {
2790       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2791         hr->verify_rem_set();
2792       }
2793       return false;
2794     }
2795 };
2796 
2797 uint G1CollectedHeap::num_task_queues() const {
2798   return _task_queues->size();
2799 }
2800 
2801 #if TASKQUEUE_STATS
2802 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2803   st->print_raw_cr("GC Task Stats");
2804   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2805   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2806 }
2807 
2808 void G1CollectedHeap::print_taskqueue_stats() const {
2809   if (!log_is_enabled(Trace, gc, task, stats)) {
2810     return;
2811   }
2812   Log(gc, task, stats) log;
2813   ResourceMark rm;
2814   LogStream ls(log.trace());
2815   outputStream* st = &ls;
2816 
2817   print_taskqueue_stats_hdr(st);
2818 
2819   TaskQueueStats totals;
2820   const uint n = num_task_queues();
2821   for (uint i = 0; i < n; ++i) {
2822     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2823     totals += task_queue(i)->stats;
2824   }
2825   st->print_raw("tot "); totals.print(st); st->cr();
2826 
2827   DEBUG_ONLY(totals.verify());
2828 }
2829 
2830 void G1CollectedHeap::reset_taskqueue_stats() {
2831   const uint n = num_task_queues();
2832   for (uint i = 0; i < n; ++i) {
2833     task_queue(i)->stats.reset();
2834   }
2835 }
2836 #endif // TASKQUEUE_STATS
2837 
2838 void G1CollectedHeap::wait_for_root_region_scanning() {
2839   double scan_wait_start = os::elapsedTime();
2840   // We have to wait until the CM threads finish scanning the
2841   // root regions as it's the only way to ensure that all the
2842   // objects on them have been correctly scanned before we start
2843   // moving them during the GC.
2844   bool waited = _cm->root_regions()->wait_until_scan_finished();
2845   double wait_time_ms = 0.0;
2846   if (waited) {
2847     double scan_wait_end = os::elapsedTime();
2848     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2849   }
2850   phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2851 }
2852 
2853 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2854 private:
2855   G1HRPrinter* _hr_printer;
2856 public:
2857   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2858 
2859   virtual bool do_heap_region(HeapRegion* r) {
2860     _hr_printer->cset(r);
2861     return false;
2862   }
2863 };
2864 
2865 void G1CollectedHeap::start_new_collection_set() {
2866   double start = os::elapsedTime();
2867 
2868   collection_set()->start_incremental_building();
2869 
2870   clear_region_attr();
2871 
2872   guarantee(_eden.length() == 0, "eden should have been cleared");
2873   policy()->transfer_survivors_to_cset(survivor());
2874 
2875   // We redo the verification but now wrt to the new CSet which
2876   // has just got initialized after the previous CSet was freed.
2877   _cm->verify_no_collection_set_oops();
2878 
2879   phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2880 }
2881 
2882 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2883 
2884   _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2885   evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2886                                             collection_set()->optional_region_length());
2887 
2888   _cm->verify_no_collection_set_oops();
2889 
2890   if (_hr_printer.is_active()) {
2891     G1PrintCollectionSetClosure cl(&_hr_printer);
2892     _collection_set.iterate(&cl);
2893     _collection_set.iterate_optional(&cl);
2894   }
2895 }
2896 
2897 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2898   if (collector_state()->in_initial_mark_gc()) {
2899     return G1HeapVerifier::G1VerifyConcurrentStart;
2900   } else if (collector_state()->in_young_only_phase()) {
2901     return G1HeapVerifier::G1VerifyYoungNormal;
2902   } else {
2903     return G1HeapVerifier::G1VerifyMixed;
2904   }
2905 }
2906 
2907 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2908   if (VerifyRememberedSets) {
2909     log_info(gc, verify)("[Verifying RemSets before GC]");
2910     VerifyRegionRemSetClosure v_cl;
2911     heap_region_iterate(&v_cl);
2912   }
2913   _verifier->verify_before_gc(type);
2914   _verifier->check_bitmaps("GC Start");
2915   verify_numa_regions("GC Start");
2916 }
2917 
2918 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2919   if (VerifyRememberedSets) {
2920     log_info(gc, verify)("[Verifying RemSets after GC]");
2921     VerifyRegionRemSetClosure v_cl;
2922     heap_region_iterate(&v_cl);
2923   }
2924   _verifier->verify_after_gc(type);
2925   _verifier->check_bitmaps("GC End");
2926   verify_numa_regions("GC End");
2927 }
2928 
2929 void G1CollectedHeap::expand_heap_after_young_collection(){
2930   size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2931   if (expand_bytes > 0) {
2932     // No need for an ergo logging here,
2933     // expansion_amount() does this when it returns a value > 0.
2934     double expand_ms;
2935     if (!expand(expand_bytes, _workers, &expand_ms)) {
2936       // We failed to expand the heap. Cannot do anything about it.
2937     }
2938     phase_times()->record_expand_heap_time(expand_ms);
2939   }
2940 }
2941 
2942 const char* G1CollectedHeap::young_gc_name() const {
2943   if (collector_state()->in_initial_mark_gc()) {
2944     return "Pause Young (Concurrent Start)";
2945   } else if (collector_state()->in_young_only_phase()) {
2946     if (collector_state()->in_young_gc_before_mixed()) {
2947       return "Pause Young (Prepare Mixed)";
2948     } else {
2949       return "Pause Young (Normal)";
2950     }
2951   } else {
2952     return "Pause Young (Mixed)";
2953   }
2954 }
2955 
2956 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2957   assert_at_safepoint_on_vm_thread();
2958   guarantee(!is_gc_active(), "collection is not reentrant");
2959 
2960   if (GCLocker::check_active_before_gc()) {
2961     return false;
2962   }
2963 
2964   GCIdMark gc_id_mark;
2965 
2966   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2967   ResourceMark rm;
2968 
2969   policy()->note_gc_start();
2970 
2971   _gc_timer_stw->register_gc_start();
2972   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2973 
2974   wait_for_root_region_scanning();
2975 
2976   print_heap_before_gc();
2977   print_heap_regions();
2978   trace_heap_before_gc(_gc_tracer_stw);
2979 
2980   _verifier->verify_region_sets_optional();
2981   _verifier->verify_dirty_young_regions();
2982 
2983   // We should not be doing initial mark unless the conc mark thread is running
2984   if (!_cm_thread->should_terminate()) {
2985     // This call will decide whether this pause is an initial-mark
2986     // pause. If it is, in_initial_mark_gc() will return true
2987     // for the duration of this pause.
2988     policy()->decide_on_conc_mark_initiation();
2989   }
2990 
2991   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2992   assert(!collector_state()->in_initial_mark_gc() ||
2993          collector_state()->in_young_only_phase(), "sanity");
2994   // We also do not allow mixed GCs during marking.
2995   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2996 
2997   // Record whether this pause is an initial mark. When the current
2998   // thread has completed its logging output and it's safe to signal
2999   // the CM thread, the flag's value in the policy has been reset.
3000   bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3001   if (should_start_conc_mark) {
3002     _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3003   }
3004 
3005   // Inner scope for scope based logging, timers, and stats collection
3006   {
3007     G1EvacuationInfo evacuation_info;
3008 
3009     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3010 
3011     GCTraceCPUTime tcpu;
3012 
3013     GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3014 
3015     uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3016                                                             workers()->active_workers(),
3017                                                             Threads::number_of_non_daemon_threads());
3018     active_workers = workers()->update_active_workers(active_workers);
3019     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3020 
3021     G1MonitoringScope ms(g1mm(),
3022                          false /* full_gc */,
3023                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3024 
3025     G1HeapTransition heap_transition(this);
3026     size_t heap_used_bytes_before_gc = used();
3027 
3028     {
3029       IsGCActiveMark x;
3030 
3031       gc_prologue(false);
3032 
3033       G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3034       verify_before_young_collection(verify_type);
3035 
3036       {
3037         // The elapsed time induced by the start time below deliberately elides
3038         // the possible verification above.
3039         double sample_start_time_sec = os::elapsedTime();
3040 
3041         // Please see comment in g1CollectedHeap.hpp and
3042         // G1CollectedHeap::ref_processing_init() to see how
3043         // reference processing currently works in G1.
3044         _ref_processor_stw->enable_discovery();
3045 
3046         // We want to temporarily turn off discovery by the
3047         // CM ref processor, if necessary, and turn it back on
3048         // on again later if we do. Using a scoped
3049         // NoRefDiscovery object will do this.
3050         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3051 
3052         policy()->record_collection_pause_start(sample_start_time_sec);
3053 
3054         // Forget the current allocation region (we might even choose it to be part
3055         // of the collection set!).
3056         _allocator->release_mutator_alloc_regions();
3057 
3058         calculate_collection_set(evacuation_info, target_pause_time_ms);
3059 
3060         G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3061         G1ParScanThreadStateSet per_thread_states(this,
3062                                                   &rdcqs,
3063                                                   workers()->active_workers(),
3064                                                   collection_set()->young_region_length(),
3065                                                   collection_set()->optional_region_length());
3066         pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3067 
3068         // Actually do the work...
3069         evacuate_initial_collection_set(&per_thread_states);
3070 
3071         if (_collection_set.optional_region_length() != 0) {
3072           evacuate_optional_collection_set(&per_thread_states);
3073         }
3074         post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3075 
3076         start_new_collection_set();
3077 
3078         _survivor_evac_stats.adjust_desired_plab_sz();
3079         _old_evac_stats.adjust_desired_plab_sz();
3080 
3081         if (should_start_conc_mark) {
3082           // We have to do this before we notify the CM threads that
3083           // they can start working to make sure that all the
3084           // appropriate initialization is done on the CM object.
3085           concurrent_mark()->post_initial_mark();
3086           // Note that we don't actually trigger the CM thread at
3087           // this point. We do that later when we're sure that
3088           // the current thread has completed its logging output.
3089         }
3090 
3091         allocate_dummy_regions();
3092 
3093         _allocator->init_mutator_alloc_regions();
3094 
3095         expand_heap_after_young_collection();
3096 
3097         double sample_end_time_sec = os::elapsedTime();
3098         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3099         policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc);
3100       }
3101 
3102       verify_after_young_collection(verify_type);
3103 
3104 #ifdef TRACESPINNING
3105       ParallelTaskTerminator::print_termination_counts();
3106 #endif
3107 
3108       gc_epilogue(false);
3109     }
3110 
3111     // Print the remainder of the GC log output.
3112     if (evacuation_failed()) {
3113       log_info(gc)("To-space exhausted");
3114     }
3115 
3116     policy()->print_phases();
3117     heap_transition.print();
3118 
3119     _hrm->verify_optional();
3120     _verifier->verify_region_sets_optional();
3121 
3122     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3123     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3124 
3125     print_heap_after_gc();
3126     print_heap_regions();
3127     trace_heap_after_gc(_gc_tracer_stw);
3128 
3129     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3130     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3131     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3132     // before any GC notifications are raised.
3133     g1mm()->update_sizes();
3134 
3135     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3136     _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3137     _gc_timer_stw->register_gc_end();
3138     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3139   }
3140   // It should now be safe to tell the concurrent mark thread to start
3141   // without its logging output interfering with the logging output
3142   // that came from the pause.
3143 
3144   if (should_start_conc_mark) {
3145     // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3146     // thread(s) could be running concurrently with us. Make sure that anything
3147     // after this point does not assume that we are the only GC thread running.
3148     // Note: of course, the actual marking work will not start until the safepoint
3149     // itself is released in SuspendibleThreadSet::desynchronize().
3150     do_concurrent_mark();
3151   }
3152 
3153   return true;
3154 }
3155 
3156 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3157   G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3158   workers()->run_task(&rsfp_task);
3159 }
3160 
3161 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3162   double remove_self_forwards_start = os::elapsedTime();
3163 
3164   remove_self_forwarding_pointers(rdcqs);
3165   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3166   _preserved_marks_set.restore(&task_executor);
3167 
3168   phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3169 }
3170 
3171 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3172   if (!_evacuation_failed) {
3173     _evacuation_failed = true;
3174   }
3175 
3176   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3177   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3178 }
3179 
3180 bool G1ParEvacuateFollowersClosure::offer_termination() {
3181   EventGCPhaseParallel event;
3182   G1ParScanThreadState* const pss = par_scan_state();
3183   start_term_time();
3184   const bool res = terminator()->offer_termination();
3185   end_term_time();
3186   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3187   return res;
3188 }
3189 
3190 void G1ParEvacuateFollowersClosure::do_void() {
3191   EventGCPhaseParallel event;
3192   G1ParScanThreadState* const pss = par_scan_state();
3193   pss->trim_queue();
3194   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3195   do {
3196     EventGCPhaseParallel event;
3197     pss->steal_and_trim_queue(queues());
3198     event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3199   } while (!offer_termination());
3200 }
3201 
3202 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3203                                         bool class_unloading_occurred) {
3204   uint num_workers = workers()->active_workers();
3205   G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3206   workers()->run_task(&unlink_task);
3207 }
3208 
3209 // Clean string dedup data structures.
3210 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3211 // record the durations of the phases. Hence the almost-copy.
3212 class G1StringDedupCleaningTask : public AbstractGangTask {
3213   BoolObjectClosure* _is_alive;
3214   OopClosure* _keep_alive;
3215   G1GCPhaseTimes* _phase_times;
3216 
3217 public:
3218   G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3219                             OopClosure* keep_alive,
3220                             G1GCPhaseTimes* phase_times) :
3221     AbstractGangTask("Partial Cleaning Task"),
3222     _is_alive(is_alive),
3223     _keep_alive(keep_alive),
3224     _phase_times(phase_times)
3225   {
3226     assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3227     StringDedup::gc_prologue(true);
3228   }
3229 
3230   ~G1StringDedupCleaningTask() {
3231     StringDedup::gc_epilogue();
3232   }
3233 
3234   void work(uint worker_id) {
3235     StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3236     {
3237       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3238       StringDedupQueue::unlink_or_oops_do(&cl);
3239     }
3240     {
3241       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3242       StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3243     }
3244   }
3245 };
3246 
3247 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3248                                             OopClosure* keep_alive,
3249                                             G1GCPhaseTimes* phase_times) {
3250   G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3251   workers()->run_task(&cl);
3252 }
3253 
3254 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3255  private:
3256   G1RedirtyCardsQueueSet* _qset;
3257   G1CollectedHeap* _g1h;
3258   BufferNode* volatile _nodes;
3259 
3260   void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3261     size_t buffer_size = _qset->buffer_size();
3262     BufferNode* next = Atomic::load(&_nodes);
3263     while (next != NULL) {
3264       BufferNode* node = next;
3265       next = Atomic::cmpxchg(node->next(), &_nodes, node);
3266       if (next == node) {
3267         cl->apply_to_buffer(node, buffer_size, worker_id);
3268         next = node->next();
3269       }
3270     }
3271   }
3272 
3273  public:
3274   G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3275     AbstractGangTask("Redirty Cards"),
3276     _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3277 
3278   virtual void work(uint worker_id) {
3279     G1GCPhaseTimes* p = _g1h->phase_times();
3280     G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3281 
3282     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3283     par_apply(&cl, worker_id);
3284 
3285     p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3286   }
3287 };
3288 
3289 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3290   double redirty_logged_cards_start = os::elapsedTime();
3291 
3292   G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3293   workers()->run_task(&redirty_task);
3294 
3295   G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3296   dcq.merge_bufferlists(rdcqs);
3297 
3298   phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3299 }
3300 
3301 // Weak Reference Processing support
3302 
3303 bool G1STWIsAliveClosure::do_object_b(oop p) {
3304   // An object is reachable if it is outside the collection set,
3305   // or is inside and copied.
3306   return !_g1h->is_in_cset(p) || p->is_forwarded();
3307 }
3308 
3309 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3310   assert(obj != NULL, "must not be NULL");
3311   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3312   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3313   // may falsely indicate that this is not the case here: however the collection set only
3314   // contains old regions when concurrent mark is not running.
3315   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3316 }
3317 
3318 // Non Copying Keep Alive closure
3319 class G1KeepAliveClosure: public OopClosure {
3320   G1CollectedHeap*_g1h;
3321 public:
3322   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3323   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3324   void do_oop(oop* p) {
3325     oop obj = *p;
3326     assert(obj != NULL, "the caller should have filtered out NULL values");
3327 
3328     const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3329     if (!region_attr.is_in_cset_or_humongous()) {
3330       return;
3331     }
3332     if (region_attr.is_in_cset()) {
3333       assert( obj->is_forwarded(), "invariant" );
3334       *p = obj->forwardee();
3335     } else {
3336       assert(!obj->is_forwarded(), "invariant" );
3337       assert(region_attr.is_humongous(),
3338              "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3339      _g1h->set_humongous_is_live(obj);
3340     }
3341   }
3342 };
3343 
3344 // Copying Keep Alive closure - can be called from both
3345 // serial and parallel code as long as different worker
3346 // threads utilize different G1ParScanThreadState instances
3347 // and different queues.
3348 
3349 class G1CopyingKeepAliveClosure: public OopClosure {
3350   G1CollectedHeap*         _g1h;
3351   G1ParScanThreadState*    _par_scan_state;
3352 
3353 public:
3354   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3355                             G1ParScanThreadState* pss):
3356     _g1h(g1h),
3357     _par_scan_state(pss)
3358   {}
3359 
3360   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3361   virtual void do_oop(      oop* p) { do_oop_work(p); }
3362 
3363   template <class T> void do_oop_work(T* p) {
3364     oop obj = RawAccess<>::oop_load(p);
3365 
3366     if (_g1h->is_in_cset_or_humongous(obj)) {
3367       // If the referent object has been forwarded (either copied
3368       // to a new location or to itself in the event of an
3369       // evacuation failure) then we need to update the reference
3370       // field and, if both reference and referent are in the G1
3371       // heap, update the RSet for the referent.
3372       //
3373       // If the referent has not been forwarded then we have to keep
3374       // it alive by policy. Therefore we have copy the referent.
3375       //
3376       // When the queue is drained (after each phase of reference processing)
3377       // the object and it's followers will be copied, the reference field set
3378       // to point to the new location, and the RSet updated.
3379       _par_scan_state->push_on_queue(p);
3380     }
3381   }
3382 };
3383 
3384 // Serial drain queue closure. Called as the 'complete_gc'
3385 // closure for each discovered list in some of the
3386 // reference processing phases.
3387 
3388 class G1STWDrainQueueClosure: public VoidClosure {
3389 protected:
3390   G1CollectedHeap* _g1h;
3391   G1ParScanThreadState* _par_scan_state;
3392 
3393   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3394 
3395 public:
3396   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3397     _g1h(g1h),
3398     _par_scan_state(pss)
3399   { }
3400 
3401   void do_void() {
3402     G1ParScanThreadState* const pss = par_scan_state();
3403     pss->trim_queue();
3404   }
3405 };
3406 
3407 // Parallel Reference Processing closures
3408 
3409 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3410 // processing during G1 evacuation pauses.
3411 
3412 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3413 private:
3414   G1CollectedHeap*          _g1h;
3415   G1ParScanThreadStateSet*  _pss;
3416   RefToScanQueueSet*        _queues;
3417   WorkGang*                 _workers;
3418 
3419 public:
3420   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3421                            G1ParScanThreadStateSet* per_thread_states,
3422                            WorkGang* workers,
3423                            RefToScanQueueSet *task_queues) :
3424     _g1h(g1h),
3425     _pss(per_thread_states),
3426     _queues(task_queues),
3427     _workers(workers)
3428   {
3429     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3430   }
3431 
3432   // Executes the given task using concurrent marking worker threads.
3433   virtual void execute(ProcessTask& task, uint ergo_workers);
3434 };
3435 
3436 // Gang task for possibly parallel reference processing
3437 
3438 class G1STWRefProcTaskProxy: public AbstractGangTask {
3439   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3440   ProcessTask&     _proc_task;
3441   G1CollectedHeap* _g1h;
3442   G1ParScanThreadStateSet* _pss;
3443   RefToScanQueueSet* _task_queues;
3444   ParallelTaskTerminator* _terminator;
3445 
3446 public:
3447   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3448                         G1CollectedHeap* g1h,
3449                         G1ParScanThreadStateSet* per_thread_states,
3450                         RefToScanQueueSet *task_queues,
3451                         ParallelTaskTerminator* terminator) :
3452     AbstractGangTask("Process reference objects in parallel"),
3453     _proc_task(proc_task),
3454     _g1h(g1h),
3455     _pss(per_thread_states),
3456     _task_queues(task_queues),
3457     _terminator(terminator)
3458   {}
3459 
3460   virtual void work(uint worker_id) {
3461     // The reference processing task executed by a single worker.
3462     ResourceMark rm;
3463     HandleMark   hm;
3464 
3465     G1STWIsAliveClosure is_alive(_g1h);
3466 
3467     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3468     pss->set_ref_discoverer(NULL);
3469 
3470     // Keep alive closure.
3471     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3472 
3473     // Complete GC closure
3474     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3475 
3476     // Call the reference processing task's work routine.
3477     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3478 
3479     // Note we cannot assert that the refs array is empty here as not all
3480     // of the processing tasks (specifically phase2 - pp2_work) execute
3481     // the complete_gc closure (which ordinarily would drain the queue) so
3482     // the queue may not be empty.
3483   }
3484 };
3485 
3486 // Driver routine for parallel reference processing.
3487 // Creates an instance of the ref processing gang
3488 // task and has the worker threads execute it.
3489 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3490   assert(_workers != NULL, "Need parallel worker threads.");
3491 
3492   assert(_workers->active_workers() >= ergo_workers,
3493          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3494          ergo_workers, _workers->active_workers());
3495   TaskTerminator terminator(ergo_workers, _queues);
3496   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3497 
3498   _workers->run_task(&proc_task_proxy, ergo_workers);
3499 }
3500 
3501 // End of weak reference support closures
3502 
3503 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3504   double ref_proc_start = os::elapsedTime();
3505 
3506   ReferenceProcessor* rp = _ref_processor_stw;
3507   assert(rp->discovery_enabled(), "should have been enabled");
3508 
3509   // Closure to test whether a referent is alive.
3510   G1STWIsAliveClosure is_alive(this);
3511 
3512   // Even when parallel reference processing is enabled, the processing
3513   // of JNI refs is serial and performed serially by the current thread
3514   // rather than by a worker. The following PSS will be used for processing
3515   // JNI refs.
3516 
3517   // Use only a single queue for this PSS.
3518   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3519   pss->set_ref_discoverer(NULL);
3520   assert(pss->queue_is_empty(), "pre-condition");
3521 
3522   // Keep alive closure.
3523   G1CopyingKeepAliveClosure keep_alive(this, pss);
3524 
3525   // Serial Complete GC closure
3526   G1STWDrainQueueClosure drain_queue(this, pss);
3527 
3528   // Setup the soft refs policy...
3529   rp->setup_policy(false);
3530 
3531   ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3532 
3533   ReferenceProcessorStats stats;
3534   if (!rp->processing_is_mt()) {
3535     // Serial reference processing...
3536     stats = rp->process_discovered_references(&is_alive,
3537                                               &keep_alive,
3538                                               &drain_queue,
3539                                               NULL,
3540                                               pt);
3541   } else {
3542     uint no_of_gc_workers = workers()->active_workers();
3543 
3544     // Parallel reference processing
3545     assert(no_of_gc_workers <= rp->max_num_queues(),
3546            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3547            no_of_gc_workers,  rp->max_num_queues());
3548 
3549     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3550     stats = rp->process_discovered_references(&is_alive,
3551                                               &keep_alive,
3552                                               &drain_queue,
3553                                               &par_task_executor,
3554                                               pt);
3555   }
3556 
3557   _gc_tracer_stw->report_gc_reference_stats(stats);
3558 
3559   // We have completed copying any necessary live referent objects.
3560   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3561 
3562   make_pending_list_reachable();
3563 
3564   assert(!rp->discovery_enabled(), "Postcondition");
3565   rp->verify_no_references_recorded();
3566 
3567   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3568   phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3569 }
3570 
3571 void G1CollectedHeap::make_pending_list_reachable() {
3572   if (collector_state()->in_initial_mark_gc()) {
3573     oop pll_head = Universe::reference_pending_list();
3574     if (pll_head != NULL) {
3575       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3576       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3577     }
3578   }
3579 }
3580 
3581 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3582   double merge_pss_time_start = os::elapsedTime();
3583   per_thread_states->flush();
3584   phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3585 }
3586 
3587 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3588   _expand_heap_after_alloc_failure = true;
3589   _evacuation_failed = false;
3590 
3591   // Disable the hot card cache.
3592   _hot_card_cache->reset_hot_cache_claimed_index();
3593   _hot_card_cache->set_use_cache(false);
3594 
3595   // Initialize the GC alloc regions.
3596   _allocator->init_gc_alloc_regions(evacuation_info);
3597 
3598   {
3599     Ticks start = Ticks::now();
3600     rem_set()->prepare_for_scan_heap_roots();
3601     phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3602   }
3603 
3604   register_regions_with_region_attr();
3605   assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3606 
3607   _preserved_marks_set.assert_empty();
3608 
3609 #if COMPILER2_OR_JVMCI
3610   DerivedPointerTable::clear();
3611 #endif
3612 
3613   // InitialMark needs claim bits to keep track of the marked-through CLDs.
3614   if (collector_state()->in_initial_mark_gc()) {
3615     concurrent_mark()->pre_initial_mark();
3616 
3617     double start_clear_claimed_marks = os::elapsedTime();
3618 
3619     ClassLoaderDataGraph::clear_claimed_marks();
3620 
3621     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3622     phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3623   }
3624 
3625   // Should G1EvacuationFailureALot be in effect for this GC?
3626   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3627 }
3628 
3629 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3630 protected:
3631   G1CollectedHeap* _g1h;
3632   G1ParScanThreadStateSet* _per_thread_states;
3633   RefToScanQueueSet* _task_queues;
3634   TaskTerminator _terminator;
3635   uint _num_workers;
3636 
3637   void evacuate_live_objects(G1ParScanThreadState* pss,
3638                              uint worker_id,
3639                              G1GCPhaseTimes::GCParPhases objcopy_phase,
3640                              G1GCPhaseTimes::GCParPhases termination_phase) {
3641     G1GCPhaseTimes* p = _g1h->phase_times();
3642 
3643     Ticks start = Ticks::now();
3644     G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3645     cl.do_void();
3646 
3647     assert(pss->queue_is_empty(), "should be empty");
3648 
3649     Tickspan evac_time = (Ticks::now() - start);
3650     p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3651 
3652     p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste);
3653     p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste);
3654 
3655     if (termination_phase == G1GCPhaseTimes::Termination) {
3656       p->record_time_secs(termination_phase, worker_id, cl.term_time());
3657       p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3658     } else {
3659       p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3660       p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3661     }
3662     assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3663   }
3664 
3665   virtual void start_work(uint worker_id) { }
3666 
3667   virtual void end_work(uint worker_id) { }
3668 
3669   virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3670 
3671   virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3672 
3673 public:
3674   G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3675     AbstractGangTask(name),
3676     _g1h(G1CollectedHeap::heap()),
3677     _per_thread_states(per_thread_states),
3678     _task_queues(task_queues),
3679     _terminator(num_workers, _task_queues),
3680     _num_workers(num_workers)
3681   { }
3682 
3683   void work(uint worker_id) {
3684     start_work(worker_id);
3685 
3686     {
3687       ResourceMark rm;
3688       HandleMark   hm;
3689 
3690       G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3691       pss->set_ref_discoverer(_g1h->ref_processor_stw());
3692 
3693       scan_roots(pss, worker_id);
3694       evacuate_live_objects(pss, worker_id);
3695     }
3696 
3697     end_work(worker_id);
3698   }
3699 };
3700 
3701 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3702   G1RootProcessor* _root_processor;
3703 
3704   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3705     _root_processor->evacuate_roots(pss, worker_id);
3706     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3707     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3708   }
3709 
3710   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3711     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3712   }
3713 
3714   void start_work(uint worker_id) {
3715     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3716   }
3717 
3718   void end_work(uint worker_id) {
3719     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3720   }
3721 
3722 public:
3723   G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3724                         G1ParScanThreadStateSet* per_thread_states,
3725                         RefToScanQueueSet* task_queues,
3726                         G1RootProcessor* root_processor,
3727                         uint num_workers) :
3728     G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3729     _root_processor(root_processor)
3730   { }
3731 };
3732 
3733 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3734   G1GCPhaseTimes* p = phase_times();
3735 
3736   {
3737     Ticks start = Ticks::now();
3738     rem_set()->merge_heap_roots(true /* initial_evacuation */);
3739     p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3740   }
3741 
3742   Tickspan task_time;
3743   const uint num_workers = workers()->active_workers();
3744 
3745   Ticks start_processing = Ticks::now();
3746   {
3747     G1RootProcessor root_processor(this, num_workers);
3748     G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3749     task_time = run_task(&g1_par_task);
3750     // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3751     // To extract its code root fixup time we measure total time of this scope and
3752     // subtract from the time the WorkGang task took.
3753   }
3754   Tickspan total_processing = Ticks::now() - start_processing;
3755 
3756   p->record_initial_evac_time(task_time.seconds() * 1000.0);
3757   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3758 }
3759 
3760 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3761 
3762   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3763     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3764     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3765   }
3766 
3767   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3768     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3769   }
3770 
3771 public:
3772   G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3773                                 RefToScanQueueSet* queues,
3774                                 uint num_workers) :
3775     G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3776   }
3777 };
3778 
3779 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3780   class G1MarkScope : public MarkScope { };
3781 
3782   Tickspan task_time;
3783 
3784   Ticks start_processing = Ticks::now();
3785   {
3786     G1MarkScope code_mark_scope;
3787     G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3788     task_time = run_task(&task);
3789     // See comment in evacuate_collection_set() for the reason of the scope.
3790   }
3791   Tickspan total_processing = Ticks::now() - start_processing;
3792 
3793   G1GCPhaseTimes* p = phase_times();
3794   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3795 }
3796 
3797 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3798   const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3799 
3800   while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3801 
3802     double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3803     double time_left_ms = MaxGCPauseMillis - time_used_ms;
3804 
3805     if (time_left_ms < 0 ||
3806         !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3807       log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3808                                 _collection_set.optional_region_length(), time_left_ms);
3809       break;
3810     }
3811 
3812     {
3813       Ticks start = Ticks::now();
3814       rem_set()->merge_heap_roots(false /* initial_evacuation */);
3815       phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3816     }
3817 
3818     {
3819       Ticks start = Ticks::now();
3820       evacuate_next_optional_regions(per_thread_states);
3821       phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3822     }
3823   }
3824 
3825   _collection_set.abandon_optional_collection_set(per_thread_states);
3826 }
3827 
3828 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3829                                                    G1RedirtyCardsQueueSet* rdcqs,
3830                                                    G1ParScanThreadStateSet* per_thread_states) {
3831   rem_set()->cleanup_after_scan_heap_roots();
3832 
3833   // Process any discovered reference objects - we have
3834   // to do this _before_ we retire the GC alloc regions
3835   // as we may have to copy some 'reachable' referent
3836   // objects (and their reachable sub-graphs) that were
3837   // not copied during the pause.
3838   process_discovered_references(per_thread_states);
3839 
3840   G1STWIsAliveClosure is_alive(this);
3841   G1KeepAliveClosure keep_alive(this);
3842 
3843   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3844                               phase_times()->weak_phase_times());
3845 
3846   if (G1StringDedup::is_enabled()) {
3847     double string_dedup_time_ms = os::elapsedTime();
3848 
3849     string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
3850 
3851     double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3852     phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3853   }
3854 
3855   _allocator->release_gc_alloc_regions(evacuation_info);
3856 
3857   if (evacuation_failed()) {
3858     restore_after_evac_failure(rdcqs);
3859 
3860     // Reset the G1EvacuationFailureALot counters and flags
3861     NOT_PRODUCT(reset_evacuation_should_fail();)
3862 
3863     double recalculate_used_start = os::elapsedTime();
3864     set_used(recalculate_used());
3865     phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3866 
3867     if (_archive_allocator != NULL) {
3868       _archive_allocator->clear_used();
3869     }
3870     for (uint i = 0; i < ParallelGCThreads; i++) {
3871       if (_evacuation_failed_info_array[i].has_failed()) {
3872         _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3873       }
3874     }
3875   } else {
3876     // The "used" of the the collection set have already been subtracted
3877     // when they were freed.  Add in the bytes evacuated.
3878     increase_used(policy()->bytes_copied_during_gc());
3879   }
3880 
3881   _preserved_marks_set.assert_empty();
3882 
3883   merge_per_thread_state_info(per_thread_states);
3884 
3885   // Reset and re-enable the hot card cache.
3886   // Note the counts for the cards in the regions in the
3887   // collection set are reset when the collection set is freed.
3888   _hot_card_cache->reset_hot_cache();
3889   _hot_card_cache->set_use_cache(true);
3890 
3891   purge_code_root_memory();
3892 
3893   redirty_logged_cards(rdcqs);
3894 
3895   free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3896 
3897   eagerly_reclaim_humongous_regions();
3898 
3899   record_obj_copy_mem_stats();
3900 
3901   evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3902   evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
3903 
3904 #if COMPILER2_OR_JVMCI
3905   double start = os::elapsedTime();
3906   DerivedPointerTable::update_pointers();
3907   phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3908 #endif
3909   policy()->print_age_table();
3910 }
3911 
3912 void G1CollectedHeap::record_obj_copy_mem_stats() {
3913   policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3914 
3915   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3916                                                create_g1_evac_summary(&_old_evac_stats));
3917 }
3918 
3919 void G1CollectedHeap::free_region(HeapRegion* hr,
3920                                   FreeRegionList* free_list,
3921                                   bool skip_remset,
3922                                   bool skip_hot_card_cache,
3923                                   bool locked) {
3924   assert(!hr->is_free(), "the region should not be free");
3925   assert(!hr->is_empty(), "the region should not be empty");
3926   assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3927   assert(free_list != NULL, "pre-condition");
3928 
3929   if (G1VerifyBitmaps) {
3930     MemRegion mr(hr->bottom(), hr->end());
3931     concurrent_mark()->clear_range_in_prev_bitmap(mr);
3932   }
3933 
3934   // Clear the card counts for this region.
3935   // Note: we only need to do this if the region is not young
3936   // (since we don't refine cards in young regions).
3937   if (!skip_hot_card_cache && !hr->is_young()) {
3938     _hot_card_cache->reset_card_counts(hr);
3939   }
3940   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3941   _policy->remset_tracker()->update_at_free(hr);
3942   free_list->add_ordered(hr);
3943 }
3944 
3945 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3946                                             FreeRegionList* free_list) {
3947   assert(hr->is_humongous(), "this is only for humongous regions");
3948   assert(free_list != NULL, "pre-condition");
3949   hr->clear_humongous();
3950   free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3951 }
3952 
3953 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3954                                            const uint humongous_regions_removed) {
3955   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3956     MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3957     _old_set.bulk_remove(old_regions_removed);
3958     _humongous_set.bulk_remove(humongous_regions_removed);
3959   }
3960 
3961 }
3962 
3963 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3964   assert(list != NULL, "list can't be null");
3965   if (!list->is_empty()) {
3966     MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3967     _hrm->insert_list_into_free_list(list);
3968   }
3969 }
3970 
3971 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3972   decrease_used(bytes);
3973 }
3974 
3975 class G1FreeCollectionSetTask : public AbstractGangTask {
3976 private:
3977 
3978   // Closure applied to all regions in the collection set to do work that needs to
3979   // be done serially in a single thread.
3980   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3981   private:
3982     G1EvacuationInfo* _evacuation_info;
3983     const size_t* _surviving_young_words;
3984 
3985     // Bytes used in successfully evacuated regions before the evacuation.
3986     size_t _before_used_bytes;
3987     // Bytes used in unsucessfully evacuated regions before the evacuation
3988     size_t _after_used_bytes;
3989 
3990     size_t _bytes_allocated_in_old_since_last_gc;
3991 
3992     size_t _failure_used_words;
3993     size_t _failure_waste_words;
3994 
3995     FreeRegionList _local_free_list;
3996   public:
3997     G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3998       HeapRegionClosure(),
3999       _evacuation_info(evacuation_info),
4000       _surviving_young_words(surviving_young_words),
4001       _before_used_bytes(0),
4002       _after_used_bytes(0),
4003       _bytes_allocated_in_old_since_last_gc(0),
4004       _failure_used_words(0),
4005       _failure_waste_words(0),
4006       _local_free_list("Local Region List for CSet Freeing") {
4007     }
4008 
4009     virtual bool do_heap_region(HeapRegion* r) {
4010       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4011 
4012       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4013       g1h->clear_region_attr(r);
4014 
4015       if (r->is_young()) {
4016         assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(),
4017                "Young index %u is wrong for region %u of type %s with %u young regions",
4018                r->young_index_in_cset(),
4019                r->hrm_index(),
4020                r->get_type_str(),
4021                g1h->collection_set()->young_region_length());
4022         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4023         r->record_surv_words_in_group(words_survived);
4024       }
4025 
4026       if (!r->evacuation_failed()) {
4027         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4028         _before_used_bytes += r->used();
4029         g1h->free_region(r,
4030                          &_local_free_list,
4031                          true, /* skip_remset */
4032                          true, /* skip_hot_card_cache */
4033                          true  /* locked */);
4034       } else {
4035         r->uninstall_surv_rate_group();
4036         r->clear_young_index_in_cset();
4037         r->set_evacuation_failed(false);
4038         // When moving a young gen region to old gen, we "allocate" that whole region
4039         // there. This is in addition to any already evacuated objects. Notify the
4040         // policy about that.
4041         // Old gen regions do not cause an additional allocation: both the objects
4042         // still in the region and the ones already moved are accounted for elsewhere.
4043         if (r->is_young()) {
4044           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4045         }
4046         // The region is now considered to be old.
4047         r->set_old();
4048         // Do some allocation statistics accounting. Regions that failed evacuation
4049         // are always made old, so there is no need to update anything in the young
4050         // gen statistics, but we need to update old gen statistics.
4051         size_t used_words = r->marked_bytes() / HeapWordSize;
4052 
4053         _failure_used_words += used_words;
4054         _failure_waste_words += HeapRegion::GrainWords - used_words;
4055 
4056         g1h->old_set_add(r);
4057         _after_used_bytes += r->used();
4058       }
4059       return false;
4060     }
4061 
4062     void complete_work() {
4063       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4064 
4065       _evacuation_info->set_regions_freed(_local_free_list.length());
4066       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4067 
4068       g1h->prepend_to_freelist(&_local_free_list);
4069       g1h->decrement_summary_bytes(_before_used_bytes);
4070 
4071       G1Policy* policy = g1h->policy();
4072       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4073 
4074       g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4075     }
4076   };
4077 
4078   G1CollectionSet* _collection_set;
4079   G1SerialFreeCollectionSetClosure _cl;
4080   const size_t* _surviving_young_words;
4081 
4082   size_t _rs_length;
4083 
4084   volatile jint _serial_work_claim;
4085 
4086   struct WorkItem {
4087     uint region_idx;
4088     bool is_young;
4089     bool evacuation_failed;
4090 
4091     WorkItem(HeapRegion* r) {
4092       region_idx = r->hrm_index();
4093       is_young = r->is_young();
4094       evacuation_failed = r->evacuation_failed();
4095     }
4096   };
4097 
4098   volatile size_t _parallel_work_claim;
4099   size_t _num_work_items;
4100   WorkItem* _work_items;
4101 
4102   void do_serial_work() {
4103     // Need to grab the lock to be allowed to modify the old region list.
4104     MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4105     _collection_set->iterate(&_cl);
4106   }
4107 
4108   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4109     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4110 
4111     HeapRegion* r = g1h->region_at(region_idx);
4112     assert(!g1h->is_on_master_free_list(r), "sanity");
4113 
4114     Atomic::add(r->rem_set()->occupied_locked(), &_rs_length);
4115 
4116     if (!is_young) {
4117       g1h->hot_card_cache()->reset_card_counts(r);
4118     }
4119 
4120     if (!evacuation_failed) {
4121       r->rem_set()->clear_locked();
4122     }
4123   }
4124 
4125   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4126   private:
4127     size_t _cur_idx;
4128     WorkItem* _work_items;
4129   public:
4130     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4131 
4132     virtual bool do_heap_region(HeapRegion* r) {
4133       _work_items[_cur_idx++] = WorkItem(r);
4134       return false;
4135     }
4136   };
4137 
4138   void prepare_work() {
4139     G1PrepareFreeCollectionSetClosure cl(_work_items);
4140     _collection_set->iterate(&cl);
4141   }
4142 
4143   void complete_work() {
4144     _cl.complete_work();
4145 
4146     G1Policy* policy = G1CollectedHeap::heap()->policy();
4147     policy->record_rs_length(_rs_length);
4148     policy->cset_regions_freed();
4149   }
4150 public:
4151   G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4152     AbstractGangTask("G1 Free Collection Set"),
4153     _collection_set(collection_set),
4154     _cl(evacuation_info, surviving_young_words),
4155     _surviving_young_words(surviving_young_words),
4156     _rs_length(0),
4157     _serial_work_claim(0),
4158     _parallel_work_claim(0),
4159     _num_work_items(collection_set->region_length()),
4160     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4161     prepare_work();
4162   }
4163 
4164   ~G1FreeCollectionSetTask() {
4165     complete_work();
4166     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4167   }
4168 
4169   // Chunk size for work distribution. The chosen value has been determined experimentally
4170   // to be a good tradeoff between overhead and achievable parallelism.
4171   static uint chunk_size() { return 32; }
4172 
4173   virtual void work(uint worker_id) {
4174     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4175 
4176     // Claim serial work.
4177     if (_serial_work_claim == 0) {
4178       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4179       if (value == 0) {
4180         double serial_time = os::elapsedTime();
4181         do_serial_work();
4182         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4183       }
4184     }
4185 
4186     // Start parallel work.
4187     double young_time = 0.0;
4188     bool has_young_time = false;
4189     double non_young_time = 0.0;
4190     bool has_non_young_time = false;
4191 
4192     while (true) {
4193       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4194       size_t cur = end - chunk_size();
4195 
4196       if (cur >= _num_work_items) {
4197         break;
4198       }
4199 
4200       EventGCPhaseParallel event;
4201       double start_time = os::elapsedTime();
4202 
4203       end = MIN2(end, _num_work_items);
4204 
4205       for (; cur < end; cur++) {
4206         bool is_young = _work_items[cur].is_young;
4207 
4208         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4209 
4210         double end_time = os::elapsedTime();
4211         double time_taken = end_time - start_time;
4212         if (is_young) {
4213           young_time += time_taken;
4214           has_young_time = true;
4215           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4216         } else {
4217           non_young_time += time_taken;
4218           has_non_young_time = true;
4219           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4220         }
4221         start_time = end_time;
4222       }
4223     }
4224 
4225     if (has_young_time) {
4226       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4227     }
4228     if (has_non_young_time) {
4229       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4230     }
4231   }
4232 };
4233 
4234 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4235   _eden.clear();
4236 
4237   double free_cset_start_time = os::elapsedTime();
4238 
4239   {
4240     uint const num_regions = _collection_set.region_length();
4241     uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U);
4242     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4243 
4244     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4245 
4246     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4247                         cl.name(), num_workers, num_regions);
4248     workers()->run_task(&cl, num_workers);
4249   }
4250   phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4251 
4252   collection_set->clear();
4253 }
4254 
4255 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4256  private:
4257   FreeRegionList* _free_region_list;
4258   HeapRegionSet* _proxy_set;
4259   uint _humongous_objects_reclaimed;
4260   uint _humongous_regions_reclaimed;
4261   size_t _freed_bytes;
4262  public:
4263 
4264   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4265     _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4266   }
4267 
4268   virtual bool do_heap_region(HeapRegion* r) {
4269     if (!r->is_starts_humongous()) {
4270       return false;
4271     }
4272 
4273     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4274 
4275     oop obj = (oop)r->bottom();
4276     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4277 
4278     // The following checks whether the humongous object is live are sufficient.
4279     // The main additional check (in addition to having a reference from the roots
4280     // or the young gen) is whether the humongous object has a remembered set entry.
4281     //
4282     // A humongous object cannot be live if there is no remembered set for it
4283     // because:
4284     // - there can be no references from within humongous starts regions referencing
4285     // the object because we never allocate other objects into them.
4286     // (I.e. there are no intra-region references that may be missed by the
4287     // remembered set)
4288     // - as soon there is a remembered set entry to the humongous starts region
4289     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4290     // until the end of a concurrent mark.
4291     //
4292     // It is not required to check whether the object has been found dead by marking
4293     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4294     // all objects allocated during that time are considered live.
4295     // SATB marking is even more conservative than the remembered set.
4296     // So if at this point in the collection there is no remembered set entry,
4297     // nobody has a reference to it.
4298     // At the start of collection we flush all refinement logs, and remembered sets
4299     // are completely up-to-date wrt to references to the humongous object.
4300     //
4301     // Other implementation considerations:
4302     // - never consider object arrays at this time because they would pose
4303     // considerable effort for cleaning up the the remembered sets. This is
4304     // required because stale remembered sets might reference locations that
4305     // are currently allocated into.
4306     uint region_idx = r->hrm_index();
4307     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4308         !r->rem_set()->is_empty()) {
4309       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",
4310                                region_idx,
4311                                (size_t)obj->size() * HeapWordSize,
4312                                p2i(r->bottom()),
4313                                r->rem_set()->occupied(),
4314                                r->rem_set()->strong_code_roots_list_length(),
4315                                next_bitmap->is_marked(r->bottom()),
4316                                g1h->is_humongous_reclaim_candidate(region_idx),
4317                                obj->is_typeArray()
4318                               );
4319       return false;
4320     }
4321 
4322     guarantee(obj->is_typeArray(),
4323               "Only eagerly reclaiming type arrays is supported, but the object "
4324               PTR_FORMAT " is not.", p2i(r->bottom()));
4325 
4326     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",
4327                              region_idx,
4328                              (size_t)obj->size() * HeapWordSize,
4329                              p2i(r->bottom()),
4330                              r->rem_set()->occupied(),
4331                              r->rem_set()->strong_code_roots_list_length(),
4332                              next_bitmap->is_marked(r->bottom()),
4333                              g1h->is_humongous_reclaim_candidate(region_idx),
4334                              obj->is_typeArray()
4335                             );
4336 
4337     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4338     cm->humongous_object_eagerly_reclaimed(r);
4339     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4340            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4341            region_idx,
4342            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4343            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4344     _humongous_objects_reclaimed++;
4345     do {
4346       HeapRegion* next = g1h->next_region_in_humongous(r);
4347       _freed_bytes += r->used();
4348       r->set_containing_set(NULL);
4349       _humongous_regions_reclaimed++;
4350       g1h->free_humongous_region(r, _free_region_list);
4351       r = next;
4352     } while (r != NULL);
4353 
4354     return false;
4355   }
4356 
4357   uint humongous_objects_reclaimed() {
4358     return _humongous_objects_reclaimed;
4359   }
4360 
4361   uint humongous_regions_reclaimed() {
4362     return _humongous_regions_reclaimed;
4363   }
4364 
4365   size_t bytes_freed() const {
4366     return _freed_bytes;
4367   }
4368 };
4369 
4370 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4371   assert_at_safepoint_on_vm_thread();
4372 
4373   if (!G1EagerReclaimHumongousObjects ||
4374       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4375     phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4376     return;
4377   }
4378 
4379   double start_time = os::elapsedTime();
4380 
4381   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4382 
4383   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4384   heap_region_iterate(&cl);
4385 
4386   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4387 
4388   G1HRPrinter* hrp = hr_printer();
4389   if (hrp->is_active()) {
4390     FreeRegionListIterator iter(&local_cleanup_list);
4391     while (iter.more_available()) {
4392       HeapRegion* hr = iter.get_next();
4393       hrp->cleanup(hr);
4394     }
4395   }
4396 
4397   prepend_to_freelist(&local_cleanup_list);
4398   decrement_summary_bytes(cl.bytes_freed());
4399 
4400   phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4401                                                        cl.humongous_objects_reclaimed());
4402 }
4403 
4404 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4405 public:
4406   virtual bool do_heap_region(HeapRegion* r) {
4407     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4408     G1CollectedHeap::heap()->clear_region_attr(r);
4409     r->clear_young_index_in_cset();
4410     return false;
4411   }
4412 };
4413 
4414 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4415   G1AbandonCollectionSetClosure cl;
4416   collection_set_iterate_all(&cl);
4417 
4418   collection_set->clear();
4419   collection_set->stop_incremental_building();
4420 }
4421 
4422 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4423   return _allocator->is_retained_old_region(hr);
4424 }
4425 
4426 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4427   _eden.add(hr);
4428   _policy->set_region_eden(hr);
4429 }
4430 
4431 #ifdef ASSERT
4432 
4433 class NoYoungRegionsClosure: public HeapRegionClosure {
4434 private:
4435   bool _success;
4436 public:
4437   NoYoungRegionsClosure() : _success(true) { }
4438   bool do_heap_region(HeapRegion* r) {
4439     if (r->is_young()) {
4440       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4441                             p2i(r->bottom()), p2i(r->end()));
4442       _success = false;
4443     }
4444     return false;
4445   }
4446   bool success() { return _success; }
4447 };
4448 
4449 bool G1CollectedHeap::check_young_list_empty() {
4450   bool ret = (young_regions_count() == 0);
4451 
4452   NoYoungRegionsClosure closure;
4453   heap_region_iterate(&closure);
4454   ret = ret && closure.success();
4455 
4456   return ret;
4457 }
4458 
4459 #endif // ASSERT
4460 
4461 class TearDownRegionSetsClosure : public HeapRegionClosure {
4462   HeapRegionSet *_old_set;
4463 
4464 public:
4465   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4466 
4467   bool do_heap_region(HeapRegion* r) {
4468     if (r->is_old()) {
4469       _old_set->remove(r);
4470     } else if(r->is_young()) {
4471       r->uninstall_surv_rate_group();
4472     } else {
4473       // We ignore free regions, we'll empty the free list afterwards.
4474       // We ignore humongous and archive regions, we're not tearing down these
4475       // sets.
4476       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4477              "it cannot be another type");
4478     }
4479     return false;
4480   }
4481 
4482   ~TearDownRegionSetsClosure() {
4483     assert(_old_set->is_empty(), "post-condition");
4484   }
4485 };
4486 
4487 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4488   assert_at_safepoint_on_vm_thread();
4489 
4490   if (!free_list_only) {
4491     TearDownRegionSetsClosure cl(&_old_set);
4492     heap_region_iterate(&cl);
4493 
4494     // Note that emptying the _young_list is postponed and instead done as
4495     // the first step when rebuilding the regions sets again. The reason for
4496     // this is that during a full GC string deduplication needs to know if
4497     // a collected region was young or old when the full GC was initiated.
4498   }
4499   _hrm->remove_all_free_regions();
4500 }
4501 
4502 void G1CollectedHeap::increase_used(size_t bytes) {
4503   _summary_bytes_used += bytes;
4504 }
4505 
4506 void G1CollectedHeap::decrease_used(size_t bytes) {
4507   assert(_summary_bytes_used >= bytes,
4508          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4509          _summary_bytes_used, bytes);
4510   _summary_bytes_used -= bytes;
4511 }
4512 
4513 void G1CollectedHeap::set_used(size_t bytes) {
4514   _summary_bytes_used = bytes;
4515 }
4516 
4517 class RebuildRegionSetsClosure : public HeapRegionClosure {
4518 private:
4519   bool _free_list_only;
4520 
4521   HeapRegionSet* _old_set;
4522   HeapRegionManager* _hrm;
4523 
4524   size_t _total_used;
4525 
4526 public:
4527   RebuildRegionSetsClosure(bool free_list_only,
4528                            HeapRegionSet* old_set,
4529                            HeapRegionManager* hrm) :
4530     _free_list_only(free_list_only),
4531     _old_set(old_set), _hrm(hrm), _total_used(0) {
4532     assert(_hrm->num_free_regions() == 0, "pre-condition");
4533     if (!free_list_only) {
4534       assert(_old_set->is_empty(), "pre-condition");
4535     }
4536   }
4537 
4538   bool do_heap_region(HeapRegion* r) {
4539     if (r->is_empty()) {
4540       assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4541       // Add free regions to the free list
4542       r->set_free();
4543       _hrm->insert_into_free_list(r);
4544     } else if (!_free_list_only) {
4545       assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4546 
4547       if (r->is_archive() || r->is_humongous()) {
4548         // We ignore archive and humongous regions. We left these sets unchanged.
4549       } else {
4550         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4551         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4552         r->move_to_old();
4553         _old_set->add(r);
4554       }
4555       _total_used += r->used();
4556     }
4557 
4558     return false;
4559   }
4560 
4561   size_t total_used() {
4562     return _total_used;
4563   }
4564 };
4565 
4566 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4567   assert_at_safepoint_on_vm_thread();
4568 
4569   if (!free_list_only) {
4570     _eden.clear();
4571     _survivor.clear();
4572   }
4573 
4574   RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4575   heap_region_iterate(&cl);
4576 
4577   if (!free_list_only) {
4578     set_used(cl.total_used());
4579     if (_archive_allocator != NULL) {
4580       _archive_allocator->clear_used();
4581     }
4582   }
4583   assert_used_and_recalculate_used_equal(this);
4584 }
4585 
4586 // Methods for the mutator alloc region
4587 
4588 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4589                                                       bool force,
4590                                                       uint node_index) {
4591   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4592   bool should_allocate = policy()->should_allocate_mutator_region();
4593   if (force || should_allocate) {
4594     HeapRegion* new_alloc_region = new_region(word_size,
4595                                               HeapRegionType::Eden,
4596                                               false /* do_expand */,
4597                                               node_index);
4598     if (new_alloc_region != NULL) {
4599       set_region_short_lived_locked(new_alloc_region);
4600       _hr_printer.alloc(new_alloc_region, !should_allocate);
4601       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4602       _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4603       return new_alloc_region;
4604     }
4605   }
4606   return NULL;
4607 }
4608 
4609 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4610                                                   size_t allocated_bytes) {
4611   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4612   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4613 
4614   collection_set()->add_eden_region(alloc_region);
4615   increase_used(allocated_bytes);
4616   _eden.add_used_bytes(allocated_bytes);
4617   _hr_printer.retire(alloc_region);
4618 
4619   // We update the eden sizes here, when the region is retired,
4620   // instead of when it's allocated, since this is the point that its
4621   // used space has been recorded in _summary_bytes_used.
4622   g1mm()->update_eden_size();
4623 }
4624 
4625 // Methods for the GC alloc regions
4626 
4627 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4628   if (dest.is_old()) {
4629     return true;
4630   } else {
4631     return survivor_regions_count() < policy()->max_survivor_regions();
4632   }
4633 }
4634 
4635 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4636   assert(FreeList_lock->owned_by_self(), "pre-condition");
4637 
4638   if (!has_more_regions(dest)) {
4639     return NULL;
4640   }
4641 
4642   HeapRegionType type;
4643   if (dest.is_young()) {
4644     type = HeapRegionType::Survivor;
4645   } else {
4646     type = HeapRegionType::Old;
4647   }
4648 
4649   HeapRegion* new_alloc_region = new_region(word_size,
4650                                             type,
4651                                             true /* do_expand */,
4652                                             node_index);
4653 
4654   if (new_alloc_region != NULL) {
4655     if (type.is_survivor()) {
4656       new_alloc_region->set_survivor();
4657       _survivor.add(new_alloc_region);
4658       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4659     } else {
4660       new_alloc_region->set_old();
4661       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4662     }
4663     _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4664     register_region_with_region_attr(new_alloc_region);
4665     _hr_printer.alloc(new_alloc_region);
4666     return new_alloc_region;
4667   }
4668   return NULL;
4669 }
4670 
4671 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4672                                              size_t allocated_bytes,
4673                                              G1HeapRegionAttr dest) {
4674   policy()->record_bytes_copied_during_gc(allocated_bytes);
4675   if (dest.is_old()) {
4676     old_set_add(alloc_region);
4677   } else {
4678     assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4679     _survivor.add_used_bytes(allocated_bytes);
4680   }
4681 
4682   bool const during_im = collector_state()->in_initial_mark_gc();
4683   if (during_im && allocated_bytes > 0) {
4684     _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4685   }
4686   _hr_printer.retire(alloc_region);
4687 }
4688 
4689 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4690   bool expanded = false;
4691   uint index = _hrm->find_highest_free(&expanded);
4692 
4693   if (index != G1_NO_HRM_INDEX) {
4694     if (expanded) {
4695       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4696                                 HeapRegion::GrainWords * HeapWordSize);
4697     }
4698     _hrm->allocate_free_regions_starting_at(index, 1);
4699     return region_at(index);
4700   }
4701   return NULL;
4702 }
4703 
4704 // Optimized nmethod scanning
4705 
4706 class RegisterNMethodOopClosure: public OopClosure {
4707   G1CollectedHeap* _g1h;
4708   nmethod* _nm;
4709 
4710   template <class T> void do_oop_work(T* p) {
4711     T heap_oop = RawAccess<>::oop_load(p);
4712     if (!CompressedOops::is_null(heap_oop)) {
4713       oop obj = CompressedOops::decode_not_null(heap_oop);
4714       HeapRegion* hr = _g1h->heap_region_containing(obj);
4715       assert(!hr->is_continues_humongous(),
4716              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4717              " starting at " HR_FORMAT,
4718              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4719 
4720       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4721       hr->add_strong_code_root_locked(_nm);
4722     }
4723   }
4724 
4725 public:
4726   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4727     _g1h(g1h), _nm(nm) {}
4728 
4729   void do_oop(oop* p)       { do_oop_work(p); }
4730   void do_oop(narrowOop* p) { do_oop_work(p); }
4731 };
4732 
4733 class UnregisterNMethodOopClosure: public OopClosure {
4734   G1CollectedHeap* _g1h;
4735   nmethod* _nm;
4736 
4737   template <class T> void do_oop_work(T* p) {
4738     T heap_oop = RawAccess<>::oop_load(p);
4739     if (!CompressedOops::is_null(heap_oop)) {
4740       oop obj = CompressedOops::decode_not_null(heap_oop);
4741       HeapRegion* hr = _g1h->heap_region_containing(obj);
4742       assert(!hr->is_continues_humongous(),
4743              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4744              " starting at " HR_FORMAT,
4745              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4746 
4747       hr->remove_strong_code_root(_nm);
4748     }
4749   }
4750 
4751 public:
4752   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4753     _g1h(g1h), _nm(nm) {}
4754 
4755   void do_oop(oop* p)       { do_oop_work(p); }
4756   void do_oop(narrowOop* p) { do_oop_work(p); }
4757 };
4758 
4759 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4760   guarantee(nm != NULL, "sanity");
4761   RegisterNMethodOopClosure reg_cl(this, nm);
4762   nm->oops_do(&reg_cl);
4763 }
4764 
4765 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4766   guarantee(nm != NULL, "sanity");
4767   UnregisterNMethodOopClosure reg_cl(this, nm);
4768   nm->oops_do(&reg_cl, true);
4769 }
4770 
4771 void G1CollectedHeap::purge_code_root_memory() {
4772   double purge_start = os::elapsedTime();
4773   G1CodeRootSet::purge();
4774   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4775   phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4776 }
4777 
4778 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4779   G1CollectedHeap* _g1h;
4780 
4781 public:
4782   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4783     _g1h(g1h) {}
4784 
4785   void do_code_blob(CodeBlob* cb) {
4786     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4787     if (nm == NULL) {
4788       return;
4789     }
4790 
4791     _g1h->register_nmethod(nm);
4792   }
4793 };
4794 
4795 void G1CollectedHeap::rebuild_strong_code_roots() {
4796   RebuildStrongCodeRootClosure blob_cl(this);
4797   CodeCache::blobs_do(&blob_cl);
4798 }
4799 
4800 void G1CollectedHeap::initialize_serviceability() {
4801   _g1mm->initialize_serviceability();
4802 }
4803 
4804 MemoryUsage G1CollectedHeap::memory_usage() {
4805   return _g1mm->memory_usage();
4806 }
4807 
4808 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4809   return _g1mm->memory_managers();
4810 }
4811 
4812 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4813   return _g1mm->memory_pools();
4814 }