rev 56111 : [mq]: fix

   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/g1YCTypes.hpp"
  63 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  64 #include "gc/g1/g1VMOperations.hpp"
  65 #include "gc/g1/heapRegion.inline.hpp"
  66 #include "gc/g1/heapRegionRemSet.hpp"
  67 #include "gc/g1/heapRegionSet.inline.hpp"
  68 #include "gc/shared/gcBehaviours.hpp"
  69 #include "gc/shared/gcHeapSummary.hpp"
  70 #include "gc/shared/gcId.hpp"
  71 #include "gc/shared/gcLocker.hpp"
  72 #include "gc/shared/gcTimer.hpp"
  73 #include "gc/shared/gcTrace.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   bool do_card_ptr(CardValue* card_ptr, uint worker_i) {
 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     return true;
 145   }
 146 
 147   size_t num_dirtied()   const { return _num_dirtied; }
 148 };
 149 
 150 
 151 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 152   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 153 }
 154 
 155 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 156   // The from card cache is not the memory that is actually committed. So we cannot
 157   // take advantage of the zero_filled parameter.
 158   reset_from_card_cache(start_idx, num_regions);
 159 }
 160 
 161 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
 162   Ticks start = Ticks::now();
 163   workers()->run_task(task, workers()->active_workers());
 164   return Ticks::now() - start;
 165 }
 166 
 167 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 168                                              MemRegion mr) {
 169   return new HeapRegion(hrs_index, bot(), mr);
 170 }
 171 
 172 // Private methods.
 173 
 174 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) {
 175   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 176          "the only time we use this to allocate a humongous region is "
 177          "when we are allocating a single humongous region");
 178 
 179   HeapRegion* res = _hrm->allocate_free_region(type);
 180 
 181   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 182     // Currently, only attempts to allocate GC alloc regions set
 183     // do_expand to true. So, we should only reach here during a
 184     // safepoint. If this assumption changes we might have to
 185     // reconsider the use of _expand_heap_after_alloc_failure.
 186     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 187 
 188     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 189                               word_size * HeapWordSize);
 190 
 191     if (expand(word_size * HeapWordSize)) {
 192       // Given that expand() succeeded in expanding the heap, and we
 193       // always expand the heap by an amount aligned to the heap
 194       // region size, the free list should in theory not be empty.
 195       // In either case allocate_free_region() will check for NULL.
 196       res = _hrm->allocate_free_region(type);
 197     } else {
 198       _expand_heap_after_alloc_failure = false;
 199     }
 200   }
 201   return res;
 202 }
 203 
 204 HeapWord*
 205 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 206                                                            uint num_regions,
 207                                                            size_t word_size) {
 208   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 209   assert(is_humongous(word_size), "word_size should be humongous");
 210   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 211 
 212   // Index of last region in the series.
 213   uint last = first + num_regions - 1;
 214 
 215   // We need to initialize the region(s) we just discovered. This is
 216   // a bit tricky given that it can happen concurrently with
 217   // refinement threads refining cards on these regions and
 218   // potentially wanting to refine the BOT as they are scanning
 219   // those cards (this can happen shortly after a cleanup; see CR
 220   // 6991377). So we have to set up the region(s) carefully and in
 221   // a specific order.
 222 
 223   // The word size sum of all the regions we will allocate.
 224   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 225   assert(word_size <= word_size_sum, "sanity");
 226 
 227   // This will be the "starts humongous" region.
 228   HeapRegion* first_hr = region_at(first);
 229   // The header of the new object will be placed at the bottom of
 230   // the first region.
 231   HeapWord* new_obj = first_hr->bottom();
 232   // This will be the new top of the new object.
 233   HeapWord* obj_top = new_obj + word_size;
 234 
 235   // First, we need to zero the header of the space that we will be
 236   // allocating. When we update top further down, some refinement
 237   // threads might try to scan the region. By zeroing the header we
 238   // ensure that any thread that will try to scan the region will
 239   // come across the zero klass word and bail out.
 240   //
 241   // NOTE: It would not have been correct to have used
 242   // CollectedHeap::fill_with_object() and make the space look like
 243   // an int array. The thread that is doing the allocation will
 244   // later update the object header to a potentially different array
 245   // type and, for a very short period of time, the klass and length
 246   // fields will be inconsistent. This could cause a refinement
 247   // thread to calculate the object size incorrectly.
 248   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 249 
 250   // Next, pad out the unused tail of the last region with filler
 251   // objects, for improved usage accounting.
 252   // How many words we use for filler objects.
 253   size_t word_fill_size = word_size_sum - word_size;
 254 
 255   // How many words memory we "waste" which cannot hold a filler object.
 256   size_t words_not_fillable = 0;
 257 
 258   if (word_fill_size >= min_fill_size()) {
 259     fill_with_objects(obj_top, word_fill_size);
 260   } else if (word_fill_size > 0) {
 261     // We have space to fill, but we cannot fit an object there.
 262     words_not_fillable = word_fill_size;
 263     word_fill_size = 0;
 264   }
 265 
 266   // We will set up the first region as "starts humongous". This
 267   // will also update the BOT covering all the regions to reflect
 268   // that there is a single object that starts at the bottom of the
 269   // first region.
 270   first_hr->set_starts_humongous(obj_top, word_fill_size);
 271   _policy->remset_tracker()->update_at_allocate(first_hr);
 272   // Then, if there are any, we will set up the "continues
 273   // humongous" regions.
 274   HeapRegion* hr = NULL;
 275   for (uint i = first + 1; i <= last; ++i) {
 276     hr = region_at(i);
 277     hr->set_continues_humongous(first_hr);
 278     _policy->remset_tracker()->update_at_allocate(hr);
 279   }
 280 
 281   // Up to this point no concurrent thread would have been able to
 282   // do any scanning on any region in this series. All the top
 283   // fields still point to bottom, so the intersection between
 284   // [bottom,top] and [card_start,card_end] will be empty. Before we
 285   // update the top fields, we'll do a storestore to make sure that
 286   // no thread sees the update to top before the zeroing of the
 287   // object header and the BOT initialization.
 288   OrderAccess::storestore();
 289 
 290   // Now, we will update the top fields of the "continues humongous"
 291   // regions except the last one.
 292   for (uint i = first; i < last; ++i) {
 293     hr = region_at(i);
 294     hr->set_top(hr->end());
 295   }
 296 
 297   hr = region_at(last);
 298   // If we cannot fit a filler object, we must set top to the end
 299   // of the humongous object, otherwise we cannot iterate the heap
 300   // and the BOT will not be complete.
 301   hr->set_top(hr->end() - words_not_fillable);
 302 
 303   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 304          "obj_top should be in last region");
 305 
 306   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 307 
 308   assert(words_not_fillable == 0 ||
 309          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 310          "Miscalculation in humongous allocation");
 311 
 312   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 313 
 314   for (uint i = first; i <= last; ++i) {
 315     hr = region_at(i);
 316     _humongous_set.add(hr);
 317     _hr_printer.alloc(hr);
 318   }
 319 
 320   return new_obj;
 321 }
 322 
 323 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 324   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 325   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 326 }
 327 
 328 // If could fit into free regions w/o expansion, try.
 329 // Otherwise, if can expand, do so.
 330 // Otherwise, if using ex regions might help, try with ex given back.
 331 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 332   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 333 
 334   _verifier->verify_region_sets_optional();
 335 
 336   uint first = G1_NO_HRM_INDEX;
 337   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 338 
 339   if (obj_regions == 1) {
 340     // Only one region to allocate, try to use a fast path by directly allocating
 341     // from the free lists. Do not try to expand here, we will potentially do that
 342     // later.
 343     HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
 344     if (hr != NULL) {
 345       first = hr->hrm_index();
 346     }
 347   } else {
 348     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 349     // are lucky enough to find some.
 350     first = _hrm->find_contiguous_only_empty(obj_regions);
 351     if (first != G1_NO_HRM_INDEX) {
 352       _hrm->allocate_free_regions_starting_at(first, obj_regions);
 353     }
 354   }
 355 
 356   if (first == G1_NO_HRM_INDEX) {
 357     // Policy: We could not find enough regions for the humongous object in the
 358     // free list. Look through the heap to find a mix of free and uncommitted regions.
 359     // If so, try expansion.
 360     first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
 361     if (first != G1_NO_HRM_INDEX) {
 362       // We found something. Make sure these regions are committed, i.e. expand
 363       // the heap. Alternatively we could do a defragmentation GC.
 364       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 365                                     word_size * HeapWordSize);
 366 
 367       _hrm->expand_at(first, obj_regions, workers());
 368       policy()->record_new_heap_size(num_regions());
 369 
 370 #ifdef ASSERT
 371       for (uint i = first; i < first + obj_regions; ++i) {
 372         HeapRegion* hr = region_at(i);
 373         assert(hr->is_free(), "sanity");
 374         assert(hr->is_empty(), "sanity");
 375         assert(is_on_master_free_list(hr), "sanity");
 376       }
 377 #endif
 378       _hrm->allocate_free_regions_starting_at(first, obj_regions);
 379     } else {
 380       // Policy: Potentially trigger a defragmentation GC.
 381     }
 382   }
 383 
 384   HeapWord* result = NULL;
 385   if (first != G1_NO_HRM_INDEX) {
 386     result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
 387     assert(result != NULL, "it should always return a valid result");
 388 
 389     // A successful humongous object allocation changes the used space
 390     // information of the old generation so we need to recalculate the
 391     // sizes and update the jstat counters here.
 392     g1mm()->update_sizes();
 393   }
 394 
 395   _verifier->verify_region_sets_optional();
 396 
 397   return result;
 398 }
 399 
 400 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
 401                                              size_t requested_size,
 402                                              size_t* actual_size) {
 403   assert_heap_not_locked_and_not_at_safepoint();
 404   assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
 405 
 406   return attempt_allocation(min_size, requested_size, actual_size);
 407 }
 408 
 409 HeapWord*
 410 G1CollectedHeap::mem_allocate(size_t word_size,
 411                               bool*  gc_overhead_limit_was_exceeded) {
 412   assert_heap_not_locked_and_not_at_safepoint();
 413 
 414   if (is_humongous(word_size)) {
 415     return attempt_allocation_humongous(word_size);
 416   }
 417   size_t dummy = 0;
 418   return attempt_allocation(word_size, word_size, &dummy);
 419 }
 420 
 421 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 422   ResourceMark rm; // For retrieving the thread names in log messages.
 423 
 424   // Make sure you read the note in attempt_allocation_humongous().
 425 
 426   assert_heap_not_locked_and_not_at_safepoint();
 427   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 428          "be called for humongous allocation requests");
 429 
 430   // We should only get here after the first-level allocation attempt
 431   // (attempt_allocation()) failed to allocate.
 432 
 433   // We will loop until a) we manage to successfully perform the
 434   // allocation or b) we successfully schedule a collection which
 435   // fails to perform the allocation. b) is the only case when we'll
 436   // return NULL.
 437   HeapWord* result = NULL;
 438   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 439     bool should_try_gc;
 440     uint gc_count_before;
 441 
 442     {
 443       MutexLocker x(Heap_lock);
 444       result = _allocator->attempt_allocation_locked(word_size);
 445       if (result != NULL) {
 446         return result;
 447       }
 448 
 449       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 450       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 451       // waiting because the GCLocker is active to not wait too long.
 452       if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
 453         // No need for an ergo message here, can_expand_young_list() does this when
 454         // it returns true.
 455         result = _allocator->attempt_allocation_force(word_size);
 456         if (result != NULL) {
 457           return result;
 458         }
 459       }
 460       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 461       // the GCLocker initiated GC has been performed and then retry. This includes
 462       // the case when the GC Locker is not active but has not been performed.
 463       should_try_gc = !GCLocker::needs_gc();
 464       // Read the GC count while still holding the Heap_lock.
 465       gc_count_before = total_collections();
 466     }
 467 
 468     if (should_try_gc) {
 469       bool succeeded;
 470       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 471                                    GCCause::_g1_inc_collection_pause);
 472       if (result != NULL) {
 473         assert(succeeded, "only way to get back a non-NULL result");
 474         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 475                              Thread::current()->name(), p2i(result));
 476         return result;
 477       }
 478 
 479       if (succeeded) {
 480         // We successfully scheduled a collection which failed to allocate. No
 481         // point in trying to allocate further. We'll just return NULL.
 482         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 483                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 484         return NULL;
 485       }
 486       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 487                            Thread::current()->name(), word_size);
 488     } else {
 489       // Failed to schedule a collection.
 490       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 491         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 492                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 493         return NULL;
 494       }
 495       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 496       // The GCLocker is either active or the GCLocker initiated
 497       // GC has not yet been performed. Stall until it is and
 498       // then retry the allocation.
 499       GCLocker::stall_until_clear();
 500       gclocker_retry_count += 1;
 501     }
 502 
 503     // We can reach here if we were unsuccessful in scheduling a
 504     // collection (because another thread beat us to it) or if we were
 505     // stalled due to the GC locker. In either can we should retry the
 506     // allocation attempt in case another thread successfully
 507     // performed a collection and reclaimed enough space. We do the
 508     // first attempt (without holding the Heap_lock) here and the
 509     // follow-on attempt will be at the start of the next loop
 510     // iteration (after taking the Heap_lock).
 511     size_t dummy = 0;
 512     result = _allocator->attempt_allocation(word_size, word_size, &dummy);
 513     if (result != NULL) {
 514       return result;
 515     }
 516 
 517     // Give a warning if we seem to be looping forever.
 518     if ((QueuedAllocationWarningCount > 0) &&
 519         (try_count % QueuedAllocationWarningCount == 0)) {
 520       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 521                              Thread::current()->name(), try_count, word_size);
 522     }
 523   }
 524 
 525   ShouldNotReachHere();
 526   return NULL;
 527 }
 528 
 529 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 530   assert_at_safepoint_on_vm_thread();
 531   if (_archive_allocator == NULL) {
 532     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 533   }
 534 }
 535 
 536 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 537   // Allocations in archive regions cannot be of a size that would be considered
 538   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 539   // may be different at archive-restore time.
 540   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 541 }
 542 
 543 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 544   assert_at_safepoint_on_vm_thread();
 545   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 546   if (is_archive_alloc_too_large(word_size)) {
 547     return NULL;
 548   }
 549   return _archive_allocator->archive_mem_allocate(word_size);
 550 }
 551 
 552 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 553                                               size_t end_alignment_in_bytes) {
 554   assert_at_safepoint_on_vm_thread();
 555   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 556 
 557   // Call complete_archive to do the real work, filling in the MemRegion
 558   // array with the archive regions.
 559   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 560   delete _archive_allocator;
 561   _archive_allocator = NULL;
 562 }
 563 
 564 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 565   assert(ranges != NULL, "MemRegion array NULL");
 566   assert(count != 0, "No MemRegions provided");
 567   MemRegion reserved = _hrm->reserved();
 568   for (size_t i = 0; i < count; i++) {
 569     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 570       return false;
 571     }
 572   }
 573   return true;
 574 }
 575 
 576 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 577                                             size_t count,
 578                                             bool open) {
 579   assert(!is_init_completed(), "Expect to be called at JVM init time");
 580   assert(ranges != NULL, "MemRegion array NULL");
 581   assert(count != 0, "No MemRegions provided");
 582   MutexLocker x(Heap_lock);
 583 
 584   MemRegion reserved = _hrm->reserved();
 585   HeapWord* prev_last_addr = NULL;
 586   HeapRegion* prev_last_region = NULL;
 587 
 588   // Temporarily disable pretouching of heap pages. This interface is used
 589   // when mmap'ing archived heap data in, so pre-touching is wasted.
 590   FlagSetting fs(AlwaysPreTouch, false);
 591 
 592   // Enable archive object checking used by G1MarkSweep. We have to let it know
 593   // about each archive range, so that objects in those ranges aren't marked.
 594   G1ArchiveAllocator::enable_archive_object_check();
 595 
 596   // For each specified MemRegion range, allocate the corresponding G1
 597   // regions and mark them as archive regions. We expect the ranges
 598   // in ascending starting address order, without overlap.
 599   for (size_t i = 0; i < count; i++) {
 600     MemRegion curr_range = ranges[i];
 601     HeapWord* start_address = curr_range.start();
 602     size_t word_size = curr_range.word_size();
 603     HeapWord* last_address = curr_range.last();
 604     size_t commits = 0;
 605 
 606     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 607               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 608               p2i(start_address), p2i(last_address));
 609     guarantee(start_address > prev_last_addr,
 610               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 611               p2i(start_address), p2i(prev_last_addr));
 612     prev_last_addr = last_address;
 613 
 614     // Check for ranges that start in the same G1 region in which the previous
 615     // range ended, and adjust the start address so we don't try to allocate
 616     // the same region again. If the current range is entirely within that
 617     // region, skip it, just adjusting the recorded top.
 618     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 619     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 620       start_address = start_region->end();
 621       if (start_address > last_address) {
 622         increase_used(word_size * HeapWordSize);
 623         start_region->set_top(last_address + 1);
 624         continue;
 625       }
 626       start_region->set_top(start_address);
 627       curr_range = MemRegion(start_address, last_address + 1);
 628       start_region = _hrm->addr_to_region(start_address);
 629     }
 630 
 631     // Perform the actual region allocation, exiting if it fails.
 632     // Then note how much new space we have allocated.
 633     if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
 634       return false;
 635     }
 636     increase_used(word_size * HeapWordSize);
 637     if (commits != 0) {
 638       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 639                                 HeapRegion::GrainWords * HeapWordSize * commits);
 640 
 641     }
 642 
 643     // Mark each G1 region touched by the range as archive, add it to
 644     // the old set, and set top.
 645     HeapRegion* curr_region = _hrm->addr_to_region(start_address);
 646     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 647     prev_last_region = last_region;
 648 
 649     while (curr_region != NULL) {
 650       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 651              "Region already in use (index %u)", curr_region->hrm_index());
 652       if (open) {
 653         curr_region->set_open_archive();
 654       } else {
 655         curr_region->set_closed_archive();
 656       }
 657       _hr_printer.alloc(curr_region);
 658       _archive_set.add(curr_region);
 659       HeapWord* top;
 660       HeapRegion* next_region;
 661       if (curr_region != last_region) {
 662         top = curr_region->end();
 663         next_region = _hrm->next_region_in_heap(curr_region);
 664       } else {
 665         top = last_address + 1;
 666         next_region = NULL;
 667       }
 668       curr_region->set_top(top);
 669       curr_region->set_first_dead(top);
 670       curr_region->set_end_of_live(top);
 671       curr_region = next_region;
 672     }
 673 
 674     // Notify mark-sweep of the archive
 675     G1ArchiveAllocator::set_range_archive(curr_range, open);
 676   }
 677   return true;
 678 }
 679 
 680 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 681   assert(!is_init_completed(), "Expect to be called at JVM init time");
 682   assert(ranges != NULL, "MemRegion array NULL");
 683   assert(count != 0, "No MemRegions provided");
 684   MemRegion reserved = _hrm->reserved();
 685   HeapWord *prev_last_addr = NULL;
 686   HeapRegion* prev_last_region = NULL;
 687 
 688   // For each MemRegion, create filler objects, if needed, in the G1 regions
 689   // that contain the address range. The address range actually within the
 690   // MemRegion will not be modified. That is assumed to have been initialized
 691   // elsewhere, probably via an mmap of archived heap data.
 692   MutexLocker x(Heap_lock);
 693   for (size_t i = 0; i < count; i++) {
 694     HeapWord* start_address = ranges[i].start();
 695     HeapWord* last_address = ranges[i].last();
 696 
 697     assert(reserved.contains(start_address) && reserved.contains(last_address),
 698            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 699            p2i(start_address), p2i(last_address));
 700     assert(start_address > prev_last_addr,
 701            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 702            p2i(start_address), p2i(prev_last_addr));
 703 
 704     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 705     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 706     HeapWord* bottom_address = start_region->bottom();
 707 
 708     // Check for a range beginning in the same region in which the
 709     // previous one ended.
 710     if (start_region == prev_last_region) {
 711       bottom_address = prev_last_addr + 1;
 712     }
 713 
 714     // Verify that the regions were all marked as archive regions by
 715     // alloc_archive_regions.
 716     HeapRegion* curr_region = start_region;
 717     while (curr_region != NULL) {
 718       guarantee(curr_region->is_archive(),
 719                 "Expected archive region at index %u", curr_region->hrm_index());
 720       if (curr_region != last_region) {
 721         curr_region = _hrm->next_region_in_heap(curr_region);
 722       } else {
 723         curr_region = NULL;
 724       }
 725     }
 726 
 727     prev_last_addr = last_address;
 728     prev_last_region = last_region;
 729 
 730     // Fill the memory below the allocated range with dummy object(s),
 731     // if the region bottom does not match the range start, or if the previous
 732     // range ended within the same G1 region, and there is a gap.
 733     if (start_address != bottom_address) {
 734       size_t fill_size = pointer_delta(start_address, bottom_address);
 735       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 736       increase_used(fill_size * HeapWordSize);
 737     }
 738   }
 739 }
 740 
 741 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
 742                                                      size_t desired_word_size,
 743                                                      size_t* actual_word_size) {
 744   assert_heap_not_locked_and_not_at_safepoint();
 745   assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
 746          "be called for humongous allocation requests");
 747 
 748   HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
 749 
 750   if (result == NULL) {
 751     *actual_word_size = desired_word_size;
 752     result = attempt_allocation_slow(desired_word_size);
 753   }
 754 
 755   assert_heap_not_locked();
 756   if (result != NULL) {
 757     assert(*actual_word_size != 0, "Actual size must have been set here");
 758     dirty_young_block(result, *actual_word_size);
 759   } else {
 760     *actual_word_size = 0;
 761   }
 762 
 763   return result;
 764 }
 765 
 766 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
 767   assert(!is_init_completed(), "Expect to be called at JVM init time");
 768   assert(ranges != NULL, "MemRegion array NULL");
 769   assert(count != 0, "No MemRegions provided");
 770   MemRegion reserved = _hrm->reserved();
 771   HeapWord* prev_last_addr = NULL;
 772   HeapRegion* prev_last_region = NULL;
 773   size_t size_used = 0;
 774   size_t uncommitted_regions = 0;
 775 
 776   // For each Memregion, free the G1 regions that constitute it, and
 777   // notify mark-sweep that the range is no longer to be considered 'archive.'
 778   MutexLocker x(Heap_lock);
 779   for (size_t i = 0; i < count; i++) {
 780     HeapWord* start_address = ranges[i].start();
 781     HeapWord* last_address = ranges[i].last();
 782 
 783     assert(reserved.contains(start_address) && reserved.contains(last_address),
 784            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 785            p2i(start_address), p2i(last_address));
 786     assert(start_address > prev_last_addr,
 787            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 788            p2i(start_address), p2i(prev_last_addr));
 789     size_used += ranges[i].byte_size();
 790     prev_last_addr = last_address;
 791 
 792     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 793     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 794 
 795     // Check for ranges that start in the same G1 region in which the previous
 796     // range ended, and adjust the start address so we don't try to free
 797     // the same region again. If the current range is entirely within that
 798     // region, skip it.
 799     if (start_region == prev_last_region) {
 800       start_address = start_region->end();
 801       if (start_address > last_address) {
 802         continue;
 803       }
 804       start_region = _hrm->addr_to_region(start_address);
 805     }
 806     prev_last_region = last_region;
 807 
 808     // After verifying that each region was marked as an archive region by
 809     // alloc_archive_regions, set it free and empty and uncommit it.
 810     HeapRegion* curr_region = start_region;
 811     while (curr_region != NULL) {
 812       guarantee(curr_region->is_archive(),
 813                 "Expected archive region at index %u", curr_region->hrm_index());
 814       uint curr_index = curr_region->hrm_index();
 815       _archive_set.remove(curr_region);
 816       curr_region->set_free();
 817       curr_region->set_top(curr_region->bottom());
 818       if (curr_region != last_region) {
 819         curr_region = _hrm->next_region_in_heap(curr_region);
 820       } else {
 821         curr_region = NULL;
 822       }
 823       _hrm->shrink_at(curr_index, 1);
 824       uncommitted_regions++;
 825     }
 826 
 827     // Notify mark-sweep that this is no longer an archive range.
 828     G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
 829   }
 830 
 831   if (uncommitted_regions != 0) {
 832     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 833                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 834   }
 835   decrease_used(size_used);
 836 }
 837 
 838 oop G1CollectedHeap::materialize_archived_object(oop obj) {
 839   assert(obj != NULL, "archived obj is NULL");
 840   assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
 841 
 842   // Loading an archived object makes it strongly reachable. If it is
 843   // loaded during concurrent marking, it must be enqueued to the SATB
 844   // queue, shading the previously white object gray.
 845   G1BarrierSet::enqueue(obj);
 846 
 847   return obj;
 848 }
 849 
 850 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 851   ResourceMark rm; // For retrieving the thread names in log messages.
 852 
 853   // The structure of this method has a lot of similarities to
 854   // attempt_allocation_slow(). The reason these two were not merged
 855   // into a single one is that such a method would require several "if
 856   // allocation is not humongous do this, otherwise do that"
 857   // conditional paths which would obscure its flow. In fact, an early
 858   // version of this code did use a unified method which was harder to
 859   // follow and, as a result, it had subtle bugs that were hard to
 860   // track down. So keeping these two methods separate allows each to
 861   // be more readable. It will be good to keep these two in sync as
 862   // much as possible.
 863 
 864   assert_heap_not_locked_and_not_at_safepoint();
 865   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 866          "should only be called for humongous allocations");
 867 
 868   // Humongous objects can exhaust the heap quickly, so we should check if we
 869   // need to start a marking cycle at each humongous object allocation. We do
 870   // the check before we do the actual allocation. The reason for doing it
 871   // before the allocation is that we avoid having to keep track of the newly
 872   // allocated memory while we do a GC.
 873   if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
 874                                            word_size)) {
 875     collect(GCCause::_g1_humongous_allocation);
 876   }
 877 
 878   // We will loop until a) we manage to successfully perform the
 879   // allocation or b) we successfully schedule a collection which
 880   // fails to perform the allocation. b) is the only case when we'll
 881   // return NULL.
 882   HeapWord* result = NULL;
 883   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 884     bool should_try_gc;
 885     uint gc_count_before;
 886 
 887 
 888     {
 889       MutexLocker x(Heap_lock);
 890 
 891       // Given that humongous objects are not allocated in young
 892       // regions, we'll first try to do the allocation without doing a
 893       // collection hoping that there's enough space in the heap.
 894       result = humongous_obj_allocate(word_size);
 895       if (result != NULL) {
 896         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 897         policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 898         return result;
 899       }
 900 
 901       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 902       // the GCLocker initiated GC has been performed and then retry. This includes
 903       // the case when the GC Locker is not active but has not been performed.
 904       should_try_gc = !GCLocker::needs_gc();
 905       // Read the GC count while still holding the Heap_lock.
 906       gc_count_before = total_collections();
 907     }
 908 
 909     if (should_try_gc) {
 910       bool succeeded;
 911       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 912                                    GCCause::_g1_humongous_allocation);
 913       if (result != NULL) {
 914         assert(succeeded, "only way to get back a non-NULL result");
 915         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 916                              Thread::current()->name(), p2i(result));
 917         return result;
 918       }
 919 
 920       if (succeeded) {
 921         // We successfully scheduled a collection which failed to allocate. No
 922         // point in trying to allocate further. We'll just return NULL.
 923         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 924                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 925         return NULL;
 926       }
 927       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 928                            Thread::current()->name(), word_size);
 929     } else {
 930       // Failed to schedule a collection.
 931       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 932         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 933                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 934         return NULL;
 935       }
 936       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 937       // The GCLocker is either active or the GCLocker initiated
 938       // GC has not yet been performed. Stall until it is and
 939       // then retry the allocation.
 940       GCLocker::stall_until_clear();
 941       gclocker_retry_count += 1;
 942     }
 943 
 944 
 945     // We can reach here if we were unsuccessful in scheduling a
 946     // collection (because another thread beat us to it) or if we were
 947     // stalled due to the GC locker. In either can we should retry the
 948     // allocation attempt in case another thread successfully
 949     // performed a collection and reclaimed enough space.
 950     // Humongous object allocation always needs a lock, so we wait for the retry
 951     // in the next iteration of the loop, unlike for the regular iteration case.
 952     // Give a warning if we seem to be looping forever.
 953 
 954     if ((QueuedAllocationWarningCount > 0) &&
 955         (try_count % QueuedAllocationWarningCount == 0)) {
 956       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 957                              Thread::current()->name(), try_count, word_size);
 958     }
 959   }
 960 
 961   ShouldNotReachHere();
 962   return NULL;
 963 }
 964 
 965 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 966                                                            bool expect_null_mutator_alloc_region) {
 967   assert_at_safepoint_on_vm_thread();
 968   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 969          "the current alloc region was unexpectedly found to be non-NULL");
 970 
 971   if (!is_humongous(word_size)) {
 972     return _allocator->attempt_allocation_locked(word_size);
 973   } else {
 974     HeapWord* result = humongous_obj_allocate(word_size);
 975     if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
 976       collector_state()->set_initiate_conc_mark_if_possible(true);
 977     }
 978     return result;
 979   }
 980 
 981   ShouldNotReachHere();
 982 }
 983 
 984 class PostCompactionPrinterClosure: public HeapRegionClosure {
 985 private:
 986   G1HRPrinter* _hr_printer;
 987 public:
 988   bool do_heap_region(HeapRegion* hr) {
 989     assert(!hr->is_young(), "not expecting to find young regions");
 990     _hr_printer->post_compaction(hr);
 991     return false;
 992   }
 993 
 994   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 995     : _hr_printer(hr_printer) { }
 996 };
 997 
 998 void G1CollectedHeap::print_hrm_post_compaction() {
 999   if (_hr_printer.is_active()) {
1000     PostCompactionPrinterClosure cl(hr_printer());
1001     heap_region_iterate(&cl);
1002   }
1003 }
1004 
1005 void G1CollectedHeap::abort_concurrent_cycle() {
1006   // If we start the compaction before the CM threads finish
1007   // scanning the root regions we might trip them over as we'll
1008   // be moving objects / updating references. So let's wait until
1009   // they are done. By telling them to abort, they should complete
1010   // early.
1011   _cm->root_regions()->abort();
1012   _cm->root_regions()->wait_until_scan_finished();
1013 
1014   // Disable discovery and empty the discovered lists
1015   // for the CM ref processor.
1016   _ref_processor_cm->disable_discovery();
1017   _ref_processor_cm->abandon_partial_discovery();
1018   _ref_processor_cm->verify_no_references_recorded();
1019 
1020   // Abandon current iterations of concurrent marking and concurrent
1021   // refinement, if any are in progress.
1022   concurrent_mark()->concurrent_cycle_abort();
1023 }
1024 
1025 void G1CollectedHeap::prepare_heap_for_full_collection() {
1026   // Make sure we'll choose a new allocation region afterwards.
1027   _allocator->release_mutator_alloc_region();
1028   _allocator->abandon_gc_alloc_regions();
1029 
1030   // We may have added regions to the current incremental collection
1031   // set between the last GC or pause and now. We need to clear the
1032   // incremental collection set and then start rebuilding it afresh
1033   // after this full GC.
1034   abandon_collection_set(collection_set());
1035 
1036   tear_down_region_sets(false /* free_list_only */);
1037 
1038   hrm()->prepare_for_full_collection_start();
1039 }
1040 
1041 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1042   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1043   assert_used_and_recalculate_used_equal(this);
1044   _verifier->verify_region_sets_optional();
1045   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1046   _verifier->check_bitmaps("Full GC Start");
1047 }
1048 
1049 void G1CollectedHeap::prepare_heap_for_mutators() {
1050   hrm()->prepare_for_full_collection_end();
1051 
1052   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1053   ClassLoaderDataGraph::purge();
1054   MetaspaceUtils::verify_metrics();
1055 
1056   // Prepare heap for normal collections.
1057   assert(num_free_regions() == 0, "we should not have added any free regions");
1058   rebuild_region_sets(false /* free_list_only */);
1059   abort_refinement();
1060   resize_heap_if_necessary();
1061 
1062   // Rebuild the strong code root lists for each region
1063   rebuild_strong_code_roots();
1064 
1065   // Purge code root memory
1066   purge_code_root_memory();
1067 
1068   // Start a new incremental collection set for the next pause
1069   start_new_collection_set();
1070 
1071   _allocator->init_mutator_alloc_region();
1072 
1073   // Post collection state updates.
1074   MetaspaceGC::compute_new_size();
1075 }
1076 
1077 void G1CollectedHeap::abort_refinement() {
1078   if (_hot_card_cache->use_cache()) {
1079     _hot_card_cache->reset_hot_cache();
1080   }
1081 
1082   // Discard all remembered set updates.
1083   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1084   assert(G1BarrierSet::dirty_card_queue_set().num_completed_buffers() == 0,
1085          "DCQS should be empty");
1086 }
1087 
1088 void G1CollectedHeap::verify_after_full_collection() {
1089   _hrm->verify_optional();
1090   _verifier->verify_region_sets_optional();
1091   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1092   // Clear the previous marking bitmap, if needed for bitmap verification.
1093   // Note we cannot do this when we clear the next marking bitmap in
1094   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1095   // objects marked during a full GC against the previous bitmap.
1096   // But we need to clear it before calling check_bitmaps below since
1097   // the full GC has compacted objects and updated TAMS but not updated
1098   // the prev bitmap.
1099   if (G1VerifyBitmaps) {
1100     GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1101     _cm->clear_prev_bitmap(workers());
1102   }
1103   // This call implicitly verifies that the next bitmap is clear after Full GC.
1104   _verifier->check_bitmaps("Full GC End");
1105 
1106   // At this point there should be no regions in the
1107   // entire heap tagged as young.
1108   assert(check_young_list_empty(), "young list should be empty at this point");
1109 
1110   // Note: since we've just done a full GC, concurrent
1111   // marking is no longer active. Therefore we need not
1112   // re-enable reference discovery for the CM ref processor.
1113   // That will be done at the start of the next marking cycle.
1114   // We also know that the STW processor should no longer
1115   // discover any new references.
1116   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1117   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1118   _ref_processor_stw->verify_no_references_recorded();
1119   _ref_processor_cm->verify_no_references_recorded();
1120 }
1121 
1122 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1123   // Post collection logging.
1124   // We should do this after we potentially resize the heap so
1125   // that all the COMMIT / UNCOMMIT events are generated before
1126   // the compaction events.
1127   print_hrm_post_compaction();
1128   heap_transition->print();
1129   print_heap_after_gc();
1130   print_heap_regions();
1131 #ifdef TRACESPINNING
1132   ParallelTaskTerminator::print_termination_counts();
1133 #endif
1134 }
1135 
1136 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1137                                          bool clear_all_soft_refs) {
1138   assert_at_safepoint_on_vm_thread();
1139 
1140   if (GCLocker::check_active_before_gc()) {
1141     // Full GC was not completed.
1142     return false;
1143   }
1144 
1145   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1146       soft_ref_policy()->should_clear_all_soft_refs();
1147 
1148   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1149   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1150 
1151   collector.prepare_collection();
1152   collector.collect();
1153   collector.complete_collection();
1154 
1155   // Full collection was successfully completed.
1156   return true;
1157 }
1158 
1159 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1160   // Currently, there is no facility in the do_full_collection(bool) API to notify
1161   // the caller that the collection did not succeed (e.g., because it was locked
1162   // out by the GC locker). So, right now, we'll ignore the return value.
1163   bool dummy = do_full_collection(true,                /* explicit_gc */
1164                                   clear_all_soft_refs);
1165 }
1166 
1167 void G1CollectedHeap::resize_heap_if_necessary() {
1168   assert_at_safepoint_on_vm_thread();
1169 
1170   // Capacity, free and used after the GC counted as full regions to
1171   // include the waste in the following calculations.
1172   const size_t capacity_after_gc = capacity();
1173   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1174 
1175   // This is enforced in arguments.cpp.
1176   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1177          "otherwise the code below doesn't make sense");
1178 
1179   // We don't have floating point command-line arguments
1180   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1181   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1182   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1183   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1184 
1185   // We have to be careful here as these two calculations can overflow
1186   // 32-bit size_t's.
1187   double used_after_gc_d = (double) used_after_gc;
1188   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1189   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1190 
1191   // Let's make sure that they are both under the max heap size, which
1192   // by default will make them fit into a size_t.
1193   double desired_capacity_upper_bound = (double) MaxHeapSize;
1194   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1195                                     desired_capacity_upper_bound);
1196   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1197                                     desired_capacity_upper_bound);
1198 
1199   // We can now safely turn them into size_t's.
1200   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1201   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1202 
1203   // This assert only makes sense here, before we adjust them
1204   // with respect to the min and max heap size.
1205   assert(minimum_desired_capacity <= maximum_desired_capacity,
1206          "minimum_desired_capacity = " SIZE_FORMAT ", "
1207          "maximum_desired_capacity = " SIZE_FORMAT,
1208          minimum_desired_capacity, maximum_desired_capacity);
1209 
1210   // Should not be greater than the heap max size. No need to adjust
1211   // it with respect to the heap min size as it's a lower bound (i.e.,
1212   // we'll try to make the capacity larger than it, not smaller).
1213   minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1214   // Should not be less than the heap min size. No need to adjust it
1215   // with respect to the heap max size as it's an upper bound (i.e.,
1216   // we'll try to make the capacity smaller than it, not greater).
1217   maximum_desired_capacity =  MAX2(maximum_desired_capacity, MinHeapSize);
1218 
1219   if (capacity_after_gc < minimum_desired_capacity) {
1220     // Don't expand unless it's significant
1221     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1222 
1223     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1224                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1225                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1226                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1227 
1228     expand(expand_bytes, _workers);
1229 
1230     // No expansion, now see if we want to shrink
1231   } else if (capacity_after_gc > maximum_desired_capacity) {
1232     // Capacity too large, compute shrinking size
1233     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1234 
1235     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1236                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1237                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1238                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1239 
1240     shrink(shrink_bytes);
1241   }
1242 }
1243 
1244 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1245                                                             bool do_gc,
1246                                                             bool clear_all_soft_refs,
1247                                                             bool expect_null_mutator_alloc_region,
1248                                                             bool* gc_succeeded) {
1249   *gc_succeeded = true;
1250   // Let's attempt the allocation first.
1251   HeapWord* result =
1252     attempt_allocation_at_safepoint(word_size,
1253                                     expect_null_mutator_alloc_region);
1254   if (result != NULL) {
1255     return result;
1256   }
1257 
1258   // In a G1 heap, we're supposed to keep allocation from failing by
1259   // incremental pauses.  Therefore, at least for now, we'll favor
1260   // expansion over collection.  (This might change in the future if we can
1261   // do something smarter than full collection to satisfy a failed alloc.)
1262   result = expand_and_allocate(word_size);
1263   if (result != NULL) {
1264     return result;
1265   }
1266 
1267   if (do_gc) {
1268     // Expansion didn't work, we'll try to do a Full GC.
1269     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1270                                        clear_all_soft_refs);
1271   }
1272 
1273   return NULL;
1274 }
1275 
1276 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1277                                                      bool* succeeded) {
1278   assert_at_safepoint_on_vm_thread();
1279 
1280   // Attempts to allocate followed by Full GC.
1281   HeapWord* result =
1282     satisfy_failed_allocation_helper(word_size,
1283                                      true,  /* do_gc */
1284                                      false, /* clear_all_soft_refs */
1285                                      false, /* expect_null_mutator_alloc_region */
1286                                      succeeded);
1287 
1288   if (result != NULL || !*succeeded) {
1289     return result;
1290   }
1291 
1292   // Attempts to allocate followed by Full GC that will collect all soft references.
1293   result = satisfy_failed_allocation_helper(word_size,
1294                                             true, /* do_gc */
1295                                             true, /* clear_all_soft_refs */
1296                                             true, /* expect_null_mutator_alloc_region */
1297                                             succeeded);
1298 
1299   if (result != NULL || !*succeeded) {
1300     return result;
1301   }
1302 
1303   // Attempts to allocate, no GC
1304   result = satisfy_failed_allocation_helper(word_size,
1305                                             false, /* do_gc */
1306                                             false, /* clear_all_soft_refs */
1307                                             true,  /* expect_null_mutator_alloc_region */
1308                                             succeeded);
1309 
1310   if (result != NULL) {
1311     return result;
1312   }
1313 
1314   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1315          "Flag should have been handled and cleared prior to this point");
1316 
1317   // What else?  We might try synchronous finalization later.  If the total
1318   // space available is large enough for the allocation, then a more
1319   // complete compaction phase than we've tried so far might be
1320   // appropriate.
1321   return NULL;
1322 }
1323 
1324 // Attempting to expand the heap sufficiently
1325 // to support an allocation of the given "word_size".  If
1326 // successful, perform the allocation and return the address of the
1327 // allocated block, or else "NULL".
1328 
1329 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1330   assert_at_safepoint_on_vm_thread();
1331 
1332   _verifier->verify_region_sets_optional();
1333 
1334   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1335   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1336                             word_size * HeapWordSize);
1337 
1338 
1339   if (expand(expand_bytes, _workers)) {
1340     _hrm->verify_optional();
1341     _verifier->verify_region_sets_optional();
1342     return attempt_allocation_at_safepoint(word_size,
1343                                            false /* expect_null_mutator_alloc_region */);
1344   }
1345   return NULL;
1346 }
1347 
1348 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1349   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1350   aligned_expand_bytes = align_up(aligned_expand_bytes,
1351                                        HeapRegion::GrainBytes);
1352 
1353   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1354                             expand_bytes, aligned_expand_bytes);
1355 
1356   if (is_maximal_no_gc()) {
1357     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1358     return false;
1359   }
1360 
1361   double expand_heap_start_time_sec = os::elapsedTime();
1362   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1363   assert(regions_to_expand > 0, "Must expand by at least one region");
1364 
1365   uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1366   if (expand_time_ms != NULL) {
1367     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1368   }
1369 
1370   if (expanded_by > 0) {
1371     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1372     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1373     policy()->record_new_heap_size(num_regions());
1374   } else {
1375     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1376 
1377     // The expansion of the virtual storage space was unsuccessful.
1378     // Let's see if it was because we ran out of swap.
1379     if (G1ExitOnExpansionFailure &&
1380         _hrm->available() >= regions_to_expand) {
1381       // We had head room...
1382       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1383     }
1384   }
1385   return regions_to_expand > 0;
1386 }
1387 
1388 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1389   size_t aligned_shrink_bytes =
1390     ReservedSpace::page_align_size_down(shrink_bytes);
1391   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1392                                          HeapRegion::GrainBytes);
1393   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1394 
1395   uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1396   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1397 
1398 
1399   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",
1400                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1401   if (num_regions_removed > 0) {
1402     policy()->record_new_heap_size(num_regions());
1403   } else {
1404     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1405   }
1406 }
1407 
1408 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1409   _verifier->verify_region_sets_optional();
1410 
1411   // We should only reach here at the end of a Full GC or during Remark which
1412   // means we should not not be holding to any GC alloc regions. The method
1413   // below will make sure of that and do any remaining clean up.
1414   _allocator->abandon_gc_alloc_regions();
1415 
1416   // Instead of tearing down / rebuilding the free lists here, we
1417   // could instead use the remove_all_pending() method on free_list to
1418   // remove only the ones that we need to remove.
1419   tear_down_region_sets(true /* free_list_only */);
1420   shrink_helper(shrink_bytes);
1421   rebuild_region_sets(true /* free_list_only */);
1422 
1423   _hrm->verify_optional();
1424   _verifier->verify_region_sets_optional();
1425 }
1426 
1427 class OldRegionSetChecker : public HeapRegionSetChecker {
1428 public:
1429   void check_mt_safety() {
1430     // Master Old Set MT safety protocol:
1431     // (a) If we're at a safepoint, operations on the master old set
1432     // should be invoked:
1433     // - by the VM thread (which will serialize them), or
1434     // - by the GC workers while holding the FreeList_lock, if we're
1435     //   at a safepoint for an evacuation pause (this lock is taken
1436     //   anyway when an GC alloc region is retired so that a new one
1437     //   is allocated from the free list), or
1438     // - by the GC workers while holding the OldSets_lock, if we're at a
1439     //   safepoint for a cleanup pause.
1440     // (b) If we're not at a safepoint, operations on the master old set
1441     // should be invoked while holding the Heap_lock.
1442 
1443     if (SafepointSynchronize::is_at_safepoint()) {
1444       guarantee(Thread::current()->is_VM_thread() ||
1445                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1446                 "master old set MT safety protocol at a safepoint");
1447     } else {
1448       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1449     }
1450   }
1451   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1452   const char* get_description() { return "Old Regions"; }
1453 };
1454 
1455 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1456 public:
1457   void check_mt_safety() {
1458     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1459               "May only change archive regions during initialization or safepoint.");
1460   }
1461   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1462   const char* get_description() { return "Archive Regions"; }
1463 };
1464 
1465 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1466 public:
1467   void check_mt_safety() {
1468     // Humongous Set MT safety protocol:
1469     // (a) If we're at a safepoint, operations on the master humongous
1470     // set should be invoked by either the VM thread (which will
1471     // serialize them) or by the GC workers while holding the
1472     // OldSets_lock.
1473     // (b) If we're not at a safepoint, operations on the master
1474     // humongous set should be invoked while holding the Heap_lock.
1475 
1476     if (SafepointSynchronize::is_at_safepoint()) {
1477       guarantee(Thread::current()->is_VM_thread() ||
1478                 OldSets_lock->owned_by_self(),
1479                 "master humongous set MT safety protocol at a safepoint");
1480     } else {
1481       guarantee(Heap_lock->owned_by_self(),
1482                 "master humongous set MT safety protocol outside a safepoint");
1483     }
1484   }
1485   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1486   const char* get_description() { return "Humongous Regions"; }
1487 };
1488 
1489 G1CollectedHeap::G1CollectedHeap() :
1490   CollectedHeap(),
1491   _young_gen_sampling_thread(NULL),
1492   _workers(NULL),
1493   _card_table(NULL),
1494   _soft_ref_policy(),
1495   _old_set("Old Region Set", new OldRegionSetChecker()),
1496   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1497   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1498   _bot(NULL),
1499   _listener(),
1500   _hrm(NULL),
1501   _allocator(NULL),
1502   _verifier(NULL),
1503   _summary_bytes_used(0),
1504   _archive_allocator(NULL),
1505   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1506   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1507   _expand_heap_after_alloc_failure(true),
1508   _g1mm(NULL),
1509   _humongous_reclaim_candidates(),
1510   _has_humongous_reclaim_candidates(false),
1511   _hr_printer(),
1512   _collector_state(),
1513   _old_marking_cycles_started(0),
1514   _old_marking_cycles_completed(0),
1515   _eden(),
1516   _survivor(),
1517   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1518   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1519   _policy(G1Policy::create_policy(_gc_timer_stw)),
1520   _heap_sizing_policy(NULL),
1521   _collection_set(this, _policy),
1522   _hot_card_cache(NULL),
1523   _rem_set(NULL),
1524   _cm(NULL),
1525   _cm_thread(NULL),
1526   _cr(NULL),
1527   _task_queues(NULL),
1528   _evacuation_failed(false),
1529   _evacuation_failed_info_array(NULL),
1530   _preserved_marks_set(true /* in_c_heap */),
1531 #ifndef PRODUCT
1532   _evacuation_failure_alot_for_current_gc(false),
1533   _evacuation_failure_alot_gc_number(0),
1534   _evacuation_failure_alot_count(0),
1535 #endif
1536   _ref_processor_stw(NULL),
1537   _is_alive_closure_stw(this),
1538   _is_subject_to_discovery_stw(this),
1539   _ref_processor_cm(NULL),
1540   _is_alive_closure_cm(this),
1541   _is_subject_to_discovery_cm(this),
1542   _region_attr() {
1543 
1544   _verifier = new G1HeapVerifier(this);
1545 
1546   _allocator = new G1Allocator(this);
1547 
1548   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1549 
1550   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1551 
1552   // Override the default _filler_array_max_size so that no humongous filler
1553   // objects are created.
1554   _filler_array_max_size = _humongous_object_threshold_in_words;
1555 
1556   uint n_queues = ParallelGCThreads;
1557   _task_queues = new RefToScanQueueSet(n_queues);
1558 
1559   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1560 
1561   for (uint i = 0; i < n_queues; i++) {
1562     RefToScanQueue* q = new RefToScanQueue();
1563     q->initialize();
1564     _task_queues->register_queue(i, q);
1565     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1566   }
1567 
1568   // Initialize the G1EvacuationFailureALot counters and flags.
1569   NOT_PRODUCT(reset_evacuation_should_fail();)
1570 
1571   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1572 }
1573 
1574 static size_t actual_reserved_page_size(ReservedSpace rs) {
1575   size_t page_size = os::vm_page_size();
1576   if (UseLargePages) {
1577     // There are two ways to manage large page memory.
1578     // 1. OS supports committing large page memory.
1579     // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1580     //    And ReservedSpace calls it 'special'. If we failed to set 'special',
1581     //    we reserved memory without large page.
1582     if (os::can_commit_large_page_memory() || rs.special()) {
1583       // An alignment at ReservedSpace comes from preferred page size or
1584       // heap alignment, and if the alignment came from heap alignment, it could be
1585       // larger than large pages size. So need to cap with the large page size.
1586       page_size = MIN2(rs.alignment(), os::large_page_size());
1587     }
1588   }
1589 
1590   return page_size;
1591 }
1592 
1593 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1594                                                                  size_t size,
1595                                                                  size_t translation_factor) {
1596   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1597   // Allocate a new reserved space, preferring to use large pages.
1598   ReservedSpace rs(size, preferred_page_size);
1599   size_t page_size = actual_reserved_page_size(rs);
1600   G1RegionToSpaceMapper* result  =
1601     G1RegionToSpaceMapper::create_mapper(rs,
1602                                          size,
1603                                          page_size,
1604                                          HeapRegion::GrainBytes,
1605                                          translation_factor,
1606                                          mtGC);
1607 
1608   os::trace_page_sizes_for_requested_size(description,
1609                                           size,
1610                                           preferred_page_size,
1611                                           page_size,
1612                                           rs.base(),
1613                                           rs.size());
1614 
1615   return result;
1616 }
1617 
1618 jint G1CollectedHeap::initialize_concurrent_refinement() {
1619   jint ecode = JNI_OK;
1620   _cr = G1ConcurrentRefine::create(&ecode);
1621   return ecode;
1622 }
1623 
1624 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1625   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1626   if (_young_gen_sampling_thread->osthread() == NULL) {
1627     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1628     return JNI_ENOMEM;
1629   }
1630   return JNI_OK;
1631 }
1632 
1633 jint G1CollectedHeap::initialize() {
1634   os::enable_vtime();
1635 
1636   // Necessary to satisfy locking discipline assertions.
1637 
1638   MutexLocker x(Heap_lock);
1639 
1640   // While there are no constraints in the GC code that HeapWordSize
1641   // be any particular value, there are multiple other areas in the
1642   // system which believe this to be true (e.g. oop->object_size in some
1643   // cases incorrectly returns the size in wordSize units rather than
1644   // HeapWordSize).
1645   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1646 
1647   size_t init_byte_size = InitialHeapSize;
1648   size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1649 
1650   // Ensure that the sizes are properly aligned.
1651   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1652   Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1653   Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1654 
1655   // Reserve the maximum.
1656 
1657   // When compressed oops are enabled, the preferred heap base
1658   // is calculated by subtracting the requested size from the
1659   // 32Gb boundary and using the result as the base address for
1660   // heap reservation. If the requested size is not aligned to
1661   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1662   // into the ReservedHeapSpace constructor) then the actual
1663   // base of the reserved heap may end up differing from the
1664   // address that was requested (i.e. the preferred heap base).
1665   // If this happens then we could end up using a non-optimal
1666   // compressed oops mode.
1667 
1668   ReservedSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1669                                                  HeapAlignment);
1670 
1671   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1672 
1673   // Create the barrier set for the entire reserved region.
1674   G1CardTable* ct = new G1CardTable(reserved_region());
1675   ct->initialize();
1676   G1BarrierSet* bs = new G1BarrierSet(ct);
1677   bs->initialize();
1678   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1679   BarrierSet::set_barrier_set(bs);
1680   _card_table = ct;
1681 
1682   G1BarrierSet::satb_mark_queue_set().initialize(this,
1683                                                  &bs->satb_mark_queue_buffer_allocator(),
1684                                                  G1SATBProcessCompletedThreshold,
1685                                                  G1SATBBufferEnqueueingThresholdPercent);
1686 
1687   // process_completed_buffers_threshold and max_completed_buffers are updated
1688   // later, based on the concurrent refinement object.
1689   G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1690                                                   &bs->dirty_card_queue_buffer_allocator());

1691 
1692   // Create the hot card cache.
1693   _hot_card_cache = new G1HotCardCache(this);
1694 
1695   // Carve out the G1 part of the heap.
1696   ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1697   size_t page_size = actual_reserved_page_size(heap_rs);
1698   G1RegionToSpaceMapper* heap_storage =
1699     G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1700                                               g1_rs.size(),
1701                                               page_size,
1702                                               HeapRegion::GrainBytes,
1703                                               1,
1704                                               mtJavaHeap);
1705   if(heap_storage == NULL) {
1706     vm_shutdown_during_initialization("Could not initialize G1 heap");
1707     return JNI_ERR;
1708   }
1709 
1710   os::trace_page_sizes("Heap",
1711                        MinHeapSize,
1712                        reserved_byte_size,
1713                        page_size,
1714                        heap_rs.base(),
1715                        heap_rs.size());
1716   heap_storage->set_mapping_changed_listener(&_listener);
1717 
1718   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1719   G1RegionToSpaceMapper* bot_storage =
1720     create_aux_memory_mapper("Block Offset Table",
1721                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1722                              G1BlockOffsetTable::heap_map_factor());
1723 
1724   G1RegionToSpaceMapper* cardtable_storage =
1725     create_aux_memory_mapper("Card Table",
1726                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1727                              G1CardTable::heap_map_factor());
1728 
1729   G1RegionToSpaceMapper* card_counts_storage =
1730     create_aux_memory_mapper("Card Counts Table",
1731                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1732                              G1CardCounts::heap_map_factor());
1733 
1734   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1735   G1RegionToSpaceMapper* prev_bitmap_storage =
1736     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1737   G1RegionToSpaceMapper* next_bitmap_storage =
1738     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1739 
1740   _hrm = HeapRegionManager::create_manager(this);
1741 
1742   _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1743   _card_table->initialize(cardtable_storage);
1744   // Do later initialization work for concurrent refinement.
1745   _hot_card_cache->initialize(card_counts_storage);
1746 
1747   // 6843694 - ensure that the maximum region index can fit
1748   // in the remembered set structures.
1749   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1750   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1751 
1752   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1753   // start within the first card.
1754   guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1755   // Also create a G1 rem set.
1756   _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1757   _rem_set->initialize(max_reserved_capacity(), max_regions());
1758 
1759   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1760   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1761   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1762             "too many cards per region");
1763 
1764   FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1765 
1766   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1767 
1768   {
1769     HeapWord* start = _hrm->reserved().start();
1770     HeapWord* end = _hrm->reserved().end();
1771     size_t granularity = HeapRegion::GrainBytes;
1772 
1773     _region_attr.initialize(start, end, granularity);
1774     _humongous_reclaim_candidates.initialize(start, end, granularity);
1775   }
1776 
1777   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1778                           true /* are_GC_task_threads */,
1779                           false /* are_ConcurrentGC_threads */);
1780   if (_workers == NULL) {
1781     return JNI_ENOMEM;
1782   }
1783   _workers->initialize_workers();
1784 
1785   // Create the G1ConcurrentMark data structure and thread.
1786   // (Must do this late, so that "max_regions" is defined.)
1787   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1788   if (_cm == NULL || !_cm->completed_initialization()) {
1789     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1790     return JNI_ENOMEM;
1791   }
1792   _cm_thread = _cm->cm_thread();
1793 
1794   // Now expand into the initial heap size.
1795   if (!expand(init_byte_size, _workers)) {
1796     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1797     return JNI_ENOMEM;
1798   }
1799 
1800   // Perform any initialization actions delegated to the policy.
1801   policy()->init(this, &_collection_set);
1802 
1803   jint ecode = initialize_concurrent_refinement();
1804   if (ecode != JNI_OK) {
1805     return ecode;
1806   }
1807 
1808   ecode = initialize_young_gen_sampling_thread();
1809   if (ecode != JNI_OK) {
1810     return ecode;
1811   }
1812 
1813   {
1814     G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1815     dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone());
1816     dcqs.set_max_completed_buffers(concurrent_refine()->red_zone());
1817   }
1818 
1819   // Here we allocate the dummy HeapRegion that is required by the
1820   // G1AllocRegion class.
1821   HeapRegion* dummy_region = _hrm->get_dummy_region();
1822 
1823   // We'll re-use the same region whether the alloc region will
1824   // require BOT updates or not and, if it doesn't, then a non-young
1825   // region will complain that it cannot support allocations without
1826   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1827   dummy_region->set_eden();
1828   // Make sure it's full.
1829   dummy_region->set_top(dummy_region->end());
1830   G1AllocRegion::setup(this, dummy_region);
1831 
1832   _allocator->init_mutator_alloc_region();
1833 
1834   // Do create of the monitoring and management support so that
1835   // values in the heap have been properly initialized.
1836   _g1mm = new G1MonitoringSupport(this);
1837 
1838   G1StringDedup::initialize();
1839 
1840   _preserved_marks_set.init(ParallelGCThreads);
1841 
1842   _collection_set.initialize(max_regions());
1843 
1844   return JNI_OK;
1845 }
1846 
1847 void G1CollectedHeap::stop() {
1848   // Stop all concurrent threads. We do this to make sure these threads
1849   // do not continue to execute and access resources (e.g. logging)
1850   // that are destroyed during shutdown.
1851   _cr->stop();
1852   _young_gen_sampling_thread->stop();
1853   _cm_thread->stop();
1854   if (G1StringDedup::is_enabled()) {
1855     G1StringDedup::stop();
1856   }
1857 }
1858 
1859 void G1CollectedHeap::safepoint_synchronize_begin() {
1860   SuspendibleThreadSet::synchronize();
1861 }
1862 
1863 void G1CollectedHeap::safepoint_synchronize_end() {
1864   SuspendibleThreadSet::desynchronize();
1865 }
1866 
1867 void G1CollectedHeap::post_initialize() {
1868   CollectedHeap::post_initialize();
1869   ref_processing_init();
1870 }
1871 
1872 void G1CollectedHeap::ref_processing_init() {
1873   // Reference processing in G1 currently works as follows:
1874   //
1875   // * There are two reference processor instances. One is
1876   //   used to record and process discovered references
1877   //   during concurrent marking; the other is used to
1878   //   record and process references during STW pauses
1879   //   (both full and incremental).
1880   // * Both ref processors need to 'span' the entire heap as
1881   //   the regions in the collection set may be dotted around.
1882   //
1883   // * For the concurrent marking ref processor:
1884   //   * Reference discovery is enabled at initial marking.
1885   //   * Reference discovery is disabled and the discovered
1886   //     references processed etc during remarking.
1887   //   * Reference discovery is MT (see below).
1888   //   * Reference discovery requires a barrier (see below).
1889   //   * Reference processing may or may not be MT
1890   //     (depending on the value of ParallelRefProcEnabled
1891   //     and ParallelGCThreads).
1892   //   * A full GC disables reference discovery by the CM
1893   //     ref processor and abandons any entries on it's
1894   //     discovered lists.
1895   //
1896   // * For the STW processor:
1897   //   * Non MT discovery is enabled at the start of a full GC.
1898   //   * Processing and enqueueing during a full GC is non-MT.
1899   //   * During a full GC, references are processed after marking.
1900   //
1901   //   * Discovery (may or may not be MT) is enabled at the start
1902   //     of an incremental evacuation pause.
1903   //   * References are processed near the end of a STW evacuation pause.
1904   //   * For both types of GC:
1905   //     * Discovery is atomic - i.e. not concurrent.
1906   //     * Reference discovery will not need a barrier.
1907 
1908   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1909 
1910   // Concurrent Mark ref processor
1911   _ref_processor_cm =
1912     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1913                            mt_processing,                                  // mt processing
1914                            ParallelGCThreads,                              // degree of mt processing
1915                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1916                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1917                            false,                                          // Reference discovery is not atomic
1918                            &_is_alive_closure_cm,                          // is alive closure
1919                            true);                                          // allow changes to number of processing threads
1920 
1921   // STW ref processor
1922   _ref_processor_stw =
1923     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1924                            mt_processing,                        // mt processing
1925                            ParallelGCThreads,                    // degree of mt processing
1926                            (ParallelGCThreads > 1),              // mt discovery
1927                            ParallelGCThreads,                    // degree of mt discovery
1928                            true,                                 // Reference discovery is atomic
1929                            &_is_alive_closure_stw,               // is alive closure
1930                            true);                                // allow changes to number of processing threads
1931 }
1932 
1933 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1934   return &_soft_ref_policy;
1935 }
1936 
1937 size_t G1CollectedHeap::capacity() const {
1938   return _hrm->length() * HeapRegion::GrainBytes;
1939 }
1940 
1941 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1942   return _hrm->total_free_bytes();
1943 }
1944 
1945 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1946   _hot_card_cache->drain(cl, worker_i);
1947 }
1948 
1949 void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1950   G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1951   size_t n_completed_buffers = 0;
1952   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1953     n_completed_buffers++;
1954   }
1955   assert(dcqs.num_completed_buffers() == 0, "Completed buffers exist!");
1956   phase_times()->record_thread_work_item(G1GCPhaseTimes::MergeLB, worker_i, n_completed_buffers, G1GCPhaseTimes::MergeLBProcessedBuffers);
1957 }
1958 
1959 // Computes the sum of the storage used by the various regions.
1960 size_t G1CollectedHeap::used() const {
1961   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1962   if (_archive_allocator != NULL) {
1963     result += _archive_allocator->used();
1964   }
1965   return result;
1966 }
1967 
1968 size_t G1CollectedHeap::used_unlocked() const {
1969   return _summary_bytes_used;
1970 }
1971 
1972 class SumUsedClosure: public HeapRegionClosure {
1973   size_t _used;
1974 public:
1975   SumUsedClosure() : _used(0) {}
1976   bool do_heap_region(HeapRegion* r) {
1977     _used += r->used();
1978     return false;
1979   }
1980   size_t result() { return _used; }
1981 };
1982 
1983 size_t G1CollectedHeap::recalculate_used() const {
1984   SumUsedClosure blk;
1985   heap_region_iterate(&blk);
1986   return blk.result();
1987 }
1988 
1989 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1990   switch (cause) {
1991     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1992     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1993     case GCCause::_wb_conc_mark:                        return true;
1994     default :                                           return false;
1995   }
1996 }
1997 
1998 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1999   switch (cause) {
2000     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2001     case GCCause::_g1_humongous_allocation: return true;
2002     case GCCause::_g1_periodic_collection:  return G1PeriodicGCInvokesConcurrent;
2003     default:                                return is_user_requested_concurrent_full_gc(cause);
2004   }
2005 }
2006 
2007 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2008   if(policy()->force_upgrade_to_full()) {
2009     return true;
2010   } else if (should_do_concurrent_full_gc(_gc_cause)) {
2011     return false;
2012   } else if (has_regions_left_for_allocation()) {
2013     return false;
2014   } else {
2015     return true;
2016   }
2017 }
2018 
2019 #ifndef PRODUCT
2020 void G1CollectedHeap::allocate_dummy_regions() {
2021   // Let's fill up most of the region
2022   size_t word_size = HeapRegion::GrainWords - 1024;
2023   // And as a result the region we'll allocate will be humongous.
2024   guarantee(is_humongous(word_size), "sanity");
2025 
2026   // _filler_array_max_size is set to humongous object threshold
2027   // but temporarily change it to use CollectedHeap::fill_with_object().
2028   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2029 
2030   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2031     // Let's use the existing mechanism for the allocation
2032     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2033     if (dummy_obj != NULL) {
2034       MemRegion mr(dummy_obj, word_size);
2035       CollectedHeap::fill_with_object(mr);
2036     } else {
2037       // If we can't allocate once, we probably cannot allocate
2038       // again. Let's get out of the loop.
2039       break;
2040     }
2041   }
2042 }
2043 #endif // !PRODUCT
2044 
2045 void G1CollectedHeap::increment_old_marking_cycles_started() {
2046   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2047          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2048          "Wrong marking cycle count (started: %d, completed: %d)",
2049          _old_marking_cycles_started, _old_marking_cycles_completed);
2050 
2051   _old_marking_cycles_started++;
2052 }
2053 
2054 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2055   MonitorLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2056 
2057   // We assume that if concurrent == true, then the caller is a
2058   // concurrent thread that was joined the Suspendible Thread
2059   // Set. If there's ever a cheap way to check this, we should add an
2060   // assert here.
2061 
2062   // Given that this method is called at the end of a Full GC or of a
2063   // concurrent cycle, and those can be nested (i.e., a Full GC can
2064   // interrupt a concurrent cycle), the number of full collections
2065   // completed should be either one (in the case where there was no
2066   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2067   // behind the number of full collections started.
2068 
2069   // This is the case for the inner caller, i.e. a Full GC.
2070   assert(concurrent ||
2071          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2072          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2073          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2074          "is inconsistent with _old_marking_cycles_completed = %u",
2075          _old_marking_cycles_started, _old_marking_cycles_completed);
2076 
2077   // This is the case for the outer caller, i.e. the concurrent cycle.
2078   assert(!concurrent ||
2079          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2080          "for outer caller (concurrent cycle): "
2081          "_old_marking_cycles_started = %u "
2082          "is inconsistent with _old_marking_cycles_completed = %u",
2083          _old_marking_cycles_started, _old_marking_cycles_completed);
2084 
2085   _old_marking_cycles_completed += 1;
2086 
2087   // We need to clear the "in_progress" flag in the CM thread before
2088   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2089   // is set) so that if a waiter requests another System.gc() it doesn't
2090   // incorrectly see that a marking cycle is still in progress.
2091   if (concurrent) {
2092     _cm_thread->set_idle();
2093   }
2094 
2095   // This notify_all() will ensure that a thread that called
2096   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2097   // and it's waiting for a full GC to finish will be woken up. It is
2098   // waiting in VM_G1CollectForAllocation::doit_epilogue().
2099   FullGCCount_lock->notify_all();
2100 }
2101 
2102 void G1CollectedHeap::collect(GCCause::Cause cause) {
2103   try_collect(cause, true);
2104 }
2105 
2106 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) {
2107   assert_heap_not_locked();
2108 
2109   bool gc_succeeded;
2110   bool should_retry_gc;
2111 
2112   do {
2113     should_retry_gc = false;
2114 
2115     uint gc_count_before;
2116     uint old_marking_count_before;
2117     uint full_gc_count_before;
2118 
2119     {
2120       MutexLocker ml(Heap_lock);
2121 
2122       // Read the GC count while holding the Heap_lock
2123       gc_count_before = total_collections();
2124       full_gc_count_before = total_full_collections();
2125       old_marking_count_before = _old_marking_cycles_started;
2126     }
2127 
2128     if (should_do_concurrent_full_gc(cause)) {
2129       // Schedule an initial-mark evacuation pause that will start a
2130       // concurrent cycle. We're setting word_size to 0 which means that
2131       // we are not requesting a post-GC allocation.
2132       VM_G1CollectForAllocation op(0,     /* word_size */
2133                                    gc_count_before,
2134                                    cause,
2135                                    true,  /* should_initiate_conc_mark */
2136                                    policy()->max_pause_time_ms());
2137       VMThread::execute(&op);
2138       gc_succeeded = op.gc_succeeded();
2139       if (!gc_succeeded && retry_on_gc_failure) {
2140         if (old_marking_count_before == _old_marking_cycles_started) {
2141           should_retry_gc = op.should_retry_gc();
2142         } else {
2143           // A Full GC happened while we were trying to schedule the
2144           // concurrent cycle. No point in starting a new cycle given
2145           // that the whole heap was collected anyway.
2146         }
2147 
2148         if (should_retry_gc && GCLocker::is_active_and_needs_gc()) {
2149           GCLocker::stall_until_clear();
2150         }
2151       }
2152     } else if (GCLocker::should_discard(cause, gc_count_before)) {
2153       // Return false to be consistent with VMOp failure due to
2154       // another collection slipping in after our gc_count but before
2155       // our request is processed.  _gc_locker collections upgraded by
2156       // GCLockerInvokesConcurrent are handled above and never discarded.
2157       return false;
2158     } else {
2159       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2160           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2161 
2162         // Schedule a standard evacuation pause. We're setting word_size
2163         // to 0 which means that we are not requesting a post-GC allocation.
2164         VM_G1CollectForAllocation op(0,     /* word_size */
2165                                      gc_count_before,
2166                                      cause,
2167                                      false, /* should_initiate_conc_mark */
2168                                      policy()->max_pause_time_ms());
2169         VMThread::execute(&op);
2170         gc_succeeded = op.gc_succeeded();
2171       } else {
2172         // Schedule a Full GC.
2173         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2174         VMThread::execute(&op);
2175         gc_succeeded = op.gc_succeeded();
2176       }
2177     }
2178   } while (should_retry_gc);
2179   return gc_succeeded;
2180 }
2181 
2182 bool G1CollectedHeap::is_in(const void* p) const {
2183   if (_hrm->reserved().contains(p)) {
2184     // Given that we know that p is in the reserved space,
2185     // heap_region_containing() should successfully
2186     // return the containing region.
2187     HeapRegion* hr = heap_region_containing(p);
2188     return hr->is_in(p);
2189   } else {
2190     return false;
2191   }
2192 }
2193 
2194 #ifdef ASSERT
2195 bool G1CollectedHeap::is_in_exact(const void* p) const {
2196   bool contains = reserved_region().contains(p);
2197   bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2198   if (contains && available) {
2199     return true;
2200   } else {
2201     return false;
2202   }
2203 }
2204 #endif
2205 
2206 // Iteration functions.
2207 
2208 // Iterates an ObjectClosure over all objects within a HeapRegion.
2209 
2210 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2211   ObjectClosure* _cl;
2212 public:
2213   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2214   bool do_heap_region(HeapRegion* r) {
2215     if (!r->is_continues_humongous()) {
2216       r->object_iterate(_cl);
2217     }
2218     return false;
2219   }
2220 };
2221 
2222 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2223   IterateObjectClosureRegionClosure blk(cl);
2224   heap_region_iterate(&blk);
2225 }
2226 
2227 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2228   _hrm->iterate(cl);
2229 }
2230 
2231 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2232                                                                  HeapRegionClaimer *hrclaimer,
2233                                                                  uint worker_id) const {
2234   _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2235 }
2236 
2237 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2238                                                          HeapRegionClaimer *hrclaimer) const {
2239   _hrm->par_iterate(cl, hrclaimer, 0);
2240 }
2241 
2242 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2243   _collection_set.iterate(cl);
2244 }
2245 
2246 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2247   _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2248 }
2249 
2250 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2251   HeapRegion* hr = heap_region_containing(addr);
2252   return hr->block_start(addr);
2253 }
2254 
2255 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2256   HeapRegion* hr = heap_region_containing(addr);
2257   return hr->block_is_obj(addr);
2258 }
2259 
2260 bool G1CollectedHeap::supports_tlab_allocation() const {
2261   return true;
2262 }
2263 
2264 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2265   return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2266 }
2267 
2268 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2269   return _eden.length() * HeapRegion::GrainBytes;
2270 }
2271 
2272 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2273 // must be equal to the humongous object limit.
2274 size_t G1CollectedHeap::max_tlab_size() const {
2275   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2276 }
2277 
2278 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2279   return _allocator->unsafe_max_tlab_alloc();
2280 }
2281 
2282 size_t G1CollectedHeap::max_capacity() const {
2283   return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2284 }
2285 
2286 size_t G1CollectedHeap::max_reserved_capacity() const {
2287   return _hrm->max_length() * HeapRegion::GrainBytes;
2288 }
2289 
2290 jlong G1CollectedHeap::millis_since_last_gc() {
2291   // See the notes in GenCollectedHeap::millis_since_last_gc()
2292   // for more information about the implementation.
2293   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2294                   _policy->collection_pause_end_millis();
2295   if (ret_val < 0) {
2296     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2297       ". returning zero instead.", ret_val);
2298     return 0;
2299   }
2300   return ret_val;
2301 }
2302 
2303 void G1CollectedHeap::deduplicate_string(oop str) {
2304   assert(java_lang_String::is_instance(str), "invariant");
2305 
2306   if (G1StringDedup::is_enabled()) {
2307     G1StringDedup::deduplicate(str);
2308   }
2309 }
2310 
2311 void G1CollectedHeap::prepare_for_verify() {
2312   _verifier->prepare_for_verify();
2313 }
2314 
2315 void G1CollectedHeap::verify(VerifyOption vo) {
2316   _verifier->verify(vo);
2317 }
2318 
2319 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2320   return true;
2321 }
2322 
2323 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2324   return _cm_thread->request_concurrent_phase(phase);
2325 }
2326 
2327 bool G1CollectedHeap::is_heterogeneous_heap() const {
2328   return G1Arguments::is_heterogeneous_heap();
2329 }
2330 
2331 class PrintRegionClosure: public HeapRegionClosure {
2332   outputStream* _st;
2333 public:
2334   PrintRegionClosure(outputStream* st) : _st(st) {}
2335   bool do_heap_region(HeapRegion* r) {
2336     r->print_on(_st);
2337     return false;
2338   }
2339 };
2340 
2341 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2342                                        const HeapRegion* hr,
2343                                        const VerifyOption vo) const {
2344   switch (vo) {
2345   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2346   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2347   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2348   default:                            ShouldNotReachHere();
2349   }
2350   return false; // keep some compilers happy
2351 }
2352 
2353 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2354                                        const VerifyOption vo) const {
2355   switch (vo) {
2356   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2357   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2358   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2359   default:                            ShouldNotReachHere();
2360   }
2361   return false; // keep some compilers happy
2362 }
2363 
2364 void G1CollectedHeap::print_heap_regions() const {
2365   LogTarget(Trace, gc, heap, region) lt;
2366   if (lt.is_enabled()) {
2367     LogStream ls(lt);
2368     print_regions_on(&ls);
2369   }
2370 }
2371 
2372 void G1CollectedHeap::print_on(outputStream* st) const {
2373   st->print(" %-20s", "garbage-first heap");
2374   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2375             capacity()/K, used_unlocked()/K);
2376   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2377             p2i(_hrm->reserved().start()),
2378             p2i(_hrm->reserved().end()));
2379   st->cr();
2380   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2381   uint young_regions = young_regions_count();
2382   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2383             (size_t) young_regions * HeapRegion::GrainBytes / K);
2384   uint survivor_regions = survivor_regions_count();
2385   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2386             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2387   st->cr();
2388   MetaspaceUtils::print_on(st);
2389 }
2390 
2391 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2392   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2393                "HS=humongous(starts), HC=humongous(continues), "
2394                "CS=collection set, F=free, A=archive, "
2395                "TAMS=top-at-mark-start (previous, next)");
2396   PrintRegionClosure blk(st);
2397   heap_region_iterate(&blk);
2398 }
2399 
2400 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2401   print_on(st);
2402 
2403   // Print the per-region information.
2404   print_regions_on(st);
2405 }
2406 
2407 void G1CollectedHeap::print_on_error(outputStream* st) const {
2408   this->CollectedHeap::print_on_error(st);
2409 
2410   if (_cm != NULL) {
2411     st->cr();
2412     _cm->print_on_error(st);
2413   }
2414 }
2415 
2416 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2417   workers()->print_worker_threads_on(st);
2418   _cm_thread->print_on(st);
2419   st->cr();
2420   _cm->print_worker_threads_on(st);
2421   _cr->print_threads_on(st);
2422   _young_gen_sampling_thread->print_on(st);
2423   if (G1StringDedup::is_enabled()) {
2424     G1StringDedup::print_worker_threads_on(st);
2425   }
2426 }
2427 
2428 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2429   workers()->threads_do(tc);
2430   tc->do_thread(_cm_thread);
2431   _cm->threads_do(tc);
2432   _cr->threads_do(tc);
2433   tc->do_thread(_young_gen_sampling_thread);
2434   if (G1StringDedup::is_enabled()) {
2435     G1StringDedup::threads_do(tc);
2436   }
2437 }
2438 
2439 void G1CollectedHeap::print_tracing_info() const {
2440   rem_set()->print_summary_info();
2441   concurrent_mark()->print_summary_info();
2442 }
2443 
2444 #ifndef PRODUCT
2445 // Helpful for debugging RSet issues.
2446 
2447 class PrintRSetsClosure : public HeapRegionClosure {
2448 private:
2449   const char* _msg;
2450   size_t _occupied_sum;
2451 
2452 public:
2453   bool do_heap_region(HeapRegion* r) {
2454     HeapRegionRemSet* hrrs = r->rem_set();
2455     size_t occupied = hrrs->occupied();
2456     _occupied_sum += occupied;
2457 
2458     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2459     if (occupied == 0) {
2460       tty->print_cr("  RSet is empty");
2461     } else {
2462       hrrs->print();
2463     }
2464     tty->print_cr("----------");
2465     return false;
2466   }
2467 
2468   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2469     tty->cr();
2470     tty->print_cr("========================================");
2471     tty->print_cr("%s", msg);
2472     tty->cr();
2473   }
2474 
2475   ~PrintRSetsClosure() {
2476     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2477     tty->print_cr("========================================");
2478     tty->cr();
2479   }
2480 };
2481 
2482 void G1CollectedHeap::print_cset_rsets() {
2483   PrintRSetsClosure cl("Printing CSet RSets");
2484   collection_set_iterate_all(&cl);
2485 }
2486 
2487 void G1CollectedHeap::print_all_rsets() {
2488   PrintRSetsClosure cl("Printing All RSets");;
2489   heap_region_iterate(&cl);
2490 }
2491 #endif // PRODUCT
2492 
2493 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2494   return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2495 }
2496 
2497 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2498 
2499   size_t eden_used_bytes = _eden.used_bytes();
2500   size_t survivor_used_bytes = _survivor.used_bytes();
2501   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2502 
2503   size_t eden_capacity_bytes =
2504     (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2505 
2506   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2507   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2508                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2509 }
2510 
2511 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2512   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2513                        stats->unused(), stats->used(), stats->region_end_waste(),
2514                        stats->regions_filled(), stats->direct_allocated(),
2515                        stats->failure_used(), stats->failure_waste());
2516 }
2517 
2518 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2519   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2520   gc_tracer->report_gc_heap_summary(when, heap_summary);
2521 
2522   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2523   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2524 }
2525 
2526 G1CollectedHeap* G1CollectedHeap::heap() {
2527   CollectedHeap* heap = Universe::heap();
2528   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2529   assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2530   return (G1CollectedHeap*)heap;
2531 }
2532 
2533 void G1CollectedHeap::gc_prologue(bool full) {
2534   // always_do_update_barrier = false;
2535   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2536 
2537   // This summary needs to be printed before incrementing total collections.
2538   rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2539 
2540   // Update common counters.
2541   increment_total_collections(full /* full gc */);
2542   if (full || collector_state()->in_initial_mark_gc()) {
2543     increment_old_marking_cycles_started();
2544   }
2545 
2546   // Fill TLAB's and such
2547   double start = os::elapsedTime();
2548   ensure_parsability(true);
2549   phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2550 }
2551 
2552 void G1CollectedHeap::gc_epilogue(bool full) {
2553   // Update common counters.
2554   if (full) {
2555     // Update the number of full collections that have been completed.
2556     increment_old_marking_cycles_completed(false /* concurrent */);
2557   }
2558 
2559   // We are at the end of the GC. Total collections has already been increased.
2560   rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2561 
2562   // FIXME: what is this about?
2563   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2564   // is set.
2565 #if COMPILER2_OR_JVMCI
2566   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2567 #endif
2568   // always_do_update_barrier = true;
2569 
2570   double start = os::elapsedTime();
2571   resize_all_tlabs();
2572   phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2573 
2574   MemoryService::track_memory_usage();
2575   // We have just completed a GC. Update the soft reference
2576   // policy with the new heap occupancy
2577   Universe::update_heap_info_at_gc();
2578 }
2579 
2580 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2581                                                uint gc_count_before,
2582                                                bool* succeeded,
2583                                                GCCause::Cause gc_cause) {
2584   assert_heap_not_locked_and_not_at_safepoint();
2585   VM_G1CollectForAllocation op(word_size,
2586                                gc_count_before,
2587                                gc_cause,
2588                                false, /* should_initiate_conc_mark */
2589                                policy()->max_pause_time_ms());
2590   VMThread::execute(&op);
2591 
2592   HeapWord* result = op.result();
2593   bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2594   assert(result == NULL || ret_succeeded,
2595          "the result should be NULL if the VM did not succeed");
2596   *succeeded = ret_succeeded;
2597 
2598   assert_heap_not_locked();
2599   return result;
2600 }
2601 
2602 void G1CollectedHeap::do_concurrent_mark() {
2603   MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2604   if (!_cm_thread->in_progress()) {
2605     _cm_thread->set_started();
2606     CGC_lock->notify();
2607   }
2608 }
2609 
2610 size_t G1CollectedHeap::pending_card_num() {
2611   struct CountCardsClosure : public ThreadClosure {
2612     size_t _cards;
2613     CountCardsClosure() : _cards(0) {}
2614     virtual void do_thread(Thread* t) {
2615       _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2616     }
2617   } count_from_threads;
2618   Threads::threads_do(&count_from_threads);
2619 
2620   G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2621   dcqs.verify_num_entries_in_completed_buffers();
2622 
2623   return dcqs.num_entries_in_completed_buffers() + count_from_threads._cards;
2624 }
2625 
2626 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2627   // We don't nominate objects with many remembered set entries, on
2628   // the assumption that such objects are likely still live.
2629   HeapRegionRemSet* rem_set = r->rem_set();
2630 
2631   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2632          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2633          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2634 }
2635 
2636 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure {
2637  private:
2638   size_t _total_humongous;
2639   size_t _candidate_humongous;
2640 
2641   bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2642     assert(region->is_starts_humongous(), "Must start a humongous object");
2643 
2644     oop obj = oop(region->bottom());
2645 
2646     // Dead objects cannot be eager reclaim candidates. Due to class
2647     // unloading it is unsafe to query their classes so we return early.
2648     if (g1h->is_obj_dead(obj, region)) {
2649       return false;
2650     }
2651 
2652     // If we do not have a complete remembered set for the region, then we can
2653     // not be sure that we have all references to it.
2654     if (!region->rem_set()->is_complete()) {
2655       return false;
2656     }
2657     // Candidate selection must satisfy the following constraints
2658     // while concurrent marking is in progress:
2659     //
2660     // * In order to maintain SATB invariants, an object must not be
2661     // reclaimed if it was allocated before the start of marking and
2662     // has not had its references scanned.  Such an object must have
2663     // its references (including type metadata) scanned to ensure no
2664     // live objects are missed by the marking process.  Objects
2665     // allocated after the start of concurrent marking don't need to
2666     // be scanned.
2667     //
2668     // * An object must not be reclaimed if it is on the concurrent
2669     // mark stack.  Objects allocated after the start of concurrent
2670     // marking are never pushed on the mark stack.
2671     //
2672     // Nominating only objects allocated after the start of concurrent
2673     // marking is sufficient to meet both constraints.  This may miss
2674     // some objects that satisfy the constraints, but the marking data
2675     // structures don't support efficiently performing the needed
2676     // additional tests or scrubbing of the mark stack.
2677     //
2678     // However, we presently only nominate is_typeArray() objects.
2679     // A humongous object containing references induces remembered
2680     // set entries on other regions.  In order to reclaim such an
2681     // object, those remembered sets would need to be cleaned up.
2682     //
2683     // We also treat is_typeArray() objects specially, allowing them
2684     // to be reclaimed even if allocated before the start of
2685     // concurrent mark.  For this we rely on mark stack insertion to
2686     // exclude is_typeArray() objects, preventing reclaiming an object
2687     // that is in the mark stack.  We also rely on the metadata for
2688     // such objects to be built-in and so ensured to be kept live.
2689     // Frequent allocation and drop of large binary blobs is an
2690     // important use case for eager reclaim, and this special handling
2691     // may reduce needed headroom.
2692 
2693     return obj->is_typeArray() &&
2694            g1h->is_potential_eager_reclaim_candidate(region);
2695   }
2696 
2697  public:
2698   RegisterRegionsWithRegionAttrTableClosure()
2699   : _total_humongous(0),
2700     _candidate_humongous(0) {
2701   }
2702 
2703   virtual bool do_heap_region(HeapRegion* r) {
2704     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2705 
2706     if (!r->is_starts_humongous()) {
2707       g1h->register_region_with_region_attr(r);
2708       return false;
2709     }
2710 
2711     bool is_candidate = humongous_region_is_candidate(g1h, r);
2712     uint rindex = r->hrm_index();
2713     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2714     if (is_candidate) {
2715       g1h->register_humongous_region_with_region_attr(rindex);
2716       _candidate_humongous++;
2717       // We will later handle the remembered sets of these regions.
2718     } else {
2719       g1h->register_region_with_region_attr(r);
2720     }
2721     _total_humongous++;
2722 
2723     return false;
2724   }
2725 
2726   size_t total_humongous() const { return _total_humongous; }
2727   size_t candidate_humongous() const { return _candidate_humongous; }
2728 };
2729 
2730 void G1CollectedHeap::register_regions_with_region_attr() {
2731   Ticks start = Ticks::now();
2732 
2733   RegisterRegionsWithRegionAttrTableClosure cl;
2734   heap_region_iterate(&cl);
2735 
2736   phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0,
2737                                          cl.total_humongous(),
2738                                          cl.candidate_humongous());
2739   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2740 }
2741 
2742 #ifndef PRODUCT
2743 void G1CollectedHeap::verify_region_attr_remset_update() {
2744   class VerifyRegionAttrRemSet : public HeapRegionClosure {
2745   public:
2746     virtual bool do_heap_region(HeapRegion* r) {
2747       G1CollectedHeap* g1h = G1CollectedHeap::heap();
2748       bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2749       assert(r->rem_set()->is_tracked() == needs_remset_update,
2750              "Region %u remset tracking status (%s) different to region attribute (%s)",
2751              r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2752       return false;
2753     }
2754   } cl;
2755   heap_region_iterate(&cl);
2756 }
2757 #endif
2758 
2759 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2760   public:
2761     bool do_heap_region(HeapRegion* hr) {
2762       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2763         hr->verify_rem_set();
2764       }
2765       return false;
2766     }
2767 };
2768 
2769 uint G1CollectedHeap::num_task_queues() const {
2770   return _task_queues->size();
2771 }
2772 
2773 #if TASKQUEUE_STATS
2774 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2775   st->print_raw_cr("GC Task Stats");
2776   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2777   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2778 }
2779 
2780 void G1CollectedHeap::print_taskqueue_stats() const {
2781   if (!log_is_enabled(Trace, gc, task, stats)) {
2782     return;
2783   }
2784   Log(gc, task, stats) log;
2785   ResourceMark rm;
2786   LogStream ls(log.trace());
2787   outputStream* st = &ls;
2788 
2789   print_taskqueue_stats_hdr(st);
2790 
2791   TaskQueueStats totals;
2792   const uint n = num_task_queues();
2793   for (uint i = 0; i < n; ++i) {
2794     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2795     totals += task_queue(i)->stats;
2796   }
2797   st->print_raw("tot "); totals.print(st); st->cr();
2798 
2799   DEBUG_ONLY(totals.verify());
2800 }
2801 
2802 void G1CollectedHeap::reset_taskqueue_stats() {
2803   const uint n = num_task_queues();
2804   for (uint i = 0; i < n; ++i) {
2805     task_queue(i)->stats.reset();
2806   }
2807 }
2808 #endif // TASKQUEUE_STATS
2809 
2810 void G1CollectedHeap::wait_for_root_region_scanning() {
2811   double scan_wait_start = os::elapsedTime();
2812   // We have to wait until the CM threads finish scanning the
2813   // root regions as it's the only way to ensure that all the
2814   // objects on them have been correctly scanned before we start
2815   // moving them during the GC.
2816   bool waited = _cm->root_regions()->wait_until_scan_finished();
2817   double wait_time_ms = 0.0;
2818   if (waited) {
2819     double scan_wait_end = os::elapsedTime();
2820     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2821   }
2822   phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2823 }
2824 
2825 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2826 private:
2827   G1HRPrinter* _hr_printer;
2828 public:
2829   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2830 
2831   virtual bool do_heap_region(HeapRegion* r) {
2832     _hr_printer->cset(r);
2833     return false;
2834   }
2835 };
2836 
2837 void G1CollectedHeap::start_new_collection_set() {
2838   double start = os::elapsedTime();
2839 
2840   collection_set()->start_incremental_building();
2841 
2842   clear_region_attr();
2843 
2844   guarantee(_eden.length() == 0, "eden should have been cleared");
2845   policy()->transfer_survivors_to_cset(survivor());
2846 
2847   // We redo the verification but now wrt to the new CSet which
2848   // has just got initialized after the previous CSet was freed.
2849   _cm->verify_no_collection_set_oops();
2850 
2851   phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2852 }
2853 
2854 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2855 
2856   _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2857   evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2858                                             collection_set()->optional_region_length());
2859 
2860   _cm->verify_no_collection_set_oops();
2861 
2862   if (_hr_printer.is_active()) {
2863     G1PrintCollectionSetClosure cl(&_hr_printer);
2864     _collection_set.iterate(&cl);
2865     _collection_set.iterate_optional(&cl);
2866   }
2867 }
2868 
2869 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2870   if (collector_state()->in_initial_mark_gc()) {
2871     return G1HeapVerifier::G1VerifyConcurrentStart;
2872   } else if (collector_state()->in_young_only_phase()) {
2873     return G1HeapVerifier::G1VerifyYoungNormal;
2874   } else {
2875     return G1HeapVerifier::G1VerifyMixed;
2876   }
2877 }
2878 
2879 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2880   if (VerifyRememberedSets) {
2881     log_info(gc, verify)("[Verifying RemSets before GC]");
2882     VerifyRegionRemSetClosure v_cl;
2883     heap_region_iterate(&v_cl);
2884   }
2885   _verifier->verify_before_gc(type);
2886   _verifier->check_bitmaps("GC Start");
2887 }
2888 
2889 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2890   if (VerifyRememberedSets) {
2891     log_info(gc, verify)("[Verifying RemSets after GC]");
2892     VerifyRegionRemSetClosure v_cl;
2893     heap_region_iterate(&v_cl);
2894   }
2895   _verifier->verify_after_gc(type);
2896   _verifier->check_bitmaps("GC End");
2897 }
2898 
2899 void G1CollectedHeap::expand_heap_after_young_collection(){
2900   size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2901   if (expand_bytes > 0) {
2902     // No need for an ergo logging here,
2903     // expansion_amount() does this when it returns a value > 0.
2904     double expand_ms;
2905     if (!expand(expand_bytes, _workers, &expand_ms)) {
2906       // We failed to expand the heap. Cannot do anything about it.
2907     }
2908     phase_times()->record_expand_heap_time(expand_ms);
2909   }
2910 }
2911 
2912 const char* G1CollectedHeap::young_gc_name() const {
2913   if (collector_state()->in_initial_mark_gc()) {
2914     return "Pause Young (Concurrent Start)";
2915   } else if (collector_state()->in_young_only_phase()) {
2916     if (collector_state()->in_young_gc_before_mixed()) {
2917       return "Pause Young (Prepare Mixed)";
2918     } else {
2919       return "Pause Young (Normal)";
2920     }
2921   } else {
2922     return "Pause Young (Mixed)";
2923   }
2924 }
2925 
2926 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2927   assert_at_safepoint_on_vm_thread();
2928   guarantee(!is_gc_active(), "collection is not reentrant");
2929 
2930   if (GCLocker::check_active_before_gc()) {
2931     return false;
2932   }
2933 
2934   GCIdMark gc_id_mark;
2935 
2936   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2937   ResourceMark rm;
2938 
2939   policy()->note_gc_start();
2940 
2941   _gc_timer_stw->register_gc_start();
2942   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2943 
2944   wait_for_root_region_scanning();
2945 
2946   print_heap_before_gc();
2947   print_heap_regions();
2948   trace_heap_before_gc(_gc_tracer_stw);
2949 
2950   _verifier->verify_region_sets_optional();
2951   _verifier->verify_dirty_young_regions();
2952 
2953   // We should not be doing initial mark unless the conc mark thread is running
2954   if (!_cm_thread->should_terminate()) {
2955     // This call will decide whether this pause is an initial-mark
2956     // pause. If it is, in_initial_mark_gc() will return true
2957     // for the duration of this pause.
2958     policy()->decide_on_conc_mark_initiation();
2959   }
2960 
2961   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2962   assert(!collector_state()->in_initial_mark_gc() ||
2963          collector_state()->in_young_only_phase(), "sanity");
2964   // We also do not allow mixed GCs during marking.
2965   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2966 
2967   // Record whether this pause is an initial mark. When the current
2968   // thread has completed its logging output and it's safe to signal
2969   // the CM thread, the flag's value in the policy has been reset.
2970   bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2971   if (should_start_conc_mark) {
2972     _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2973   }
2974 
2975   // Inner scope for scope based logging, timers, and stats collection
2976   {
2977     G1EvacuationInfo evacuation_info;
2978 
2979     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2980 
2981     GCTraceCPUTime tcpu;
2982 
2983     GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
2984 
2985     uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
2986                                                             workers()->active_workers(),
2987                                                             Threads::number_of_non_daemon_threads());
2988     active_workers = workers()->update_active_workers(active_workers);
2989     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2990 
2991     G1MonitoringScope ms(g1mm(),
2992                          false /* full_gc */,
2993                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2994 
2995     G1HeapTransition heap_transition(this);
2996     size_t heap_used_bytes_before_gc = used();
2997 
2998     {
2999       IsGCActiveMark x;
3000 
3001       gc_prologue(false);
3002 
3003       G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3004       verify_before_young_collection(verify_type);
3005 
3006       {
3007         // The elapsed time induced by the start time below deliberately elides
3008         // the possible verification above.
3009         double sample_start_time_sec = os::elapsedTime();
3010 
3011         // Please see comment in g1CollectedHeap.hpp and
3012         // G1CollectedHeap::ref_processing_init() to see how
3013         // reference processing currently works in G1.
3014         _ref_processor_stw->enable_discovery();
3015 
3016         // We want to temporarily turn off discovery by the
3017         // CM ref processor, if necessary, and turn it back on
3018         // on again later if we do. Using a scoped
3019         // NoRefDiscovery object will do this.
3020         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3021 
3022         policy()->record_collection_pause_start(sample_start_time_sec);
3023 
3024         // Forget the current allocation region (we might even choose it to be part
3025         // of the collection set!).
3026         _allocator->release_mutator_alloc_region();
3027 
3028         calculate_collection_set(evacuation_info, target_pause_time_ms);
3029 
3030         G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3031         G1ParScanThreadStateSet per_thread_states(this,
3032                                                   &rdcqs,
3033                                                   workers()->active_workers(),
3034                                                   collection_set()->young_region_length(),
3035                                                   collection_set()->optional_region_length());
3036         pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3037 
3038         // Actually do the work...
3039         evacuate_initial_collection_set(&per_thread_states);
3040 
3041         if (_collection_set.optional_region_length() != 0) {
3042           evacuate_optional_collection_set(&per_thread_states);
3043         }
3044         post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3045 
3046         start_new_collection_set();
3047 
3048         _survivor_evac_stats.adjust_desired_plab_sz();
3049         _old_evac_stats.adjust_desired_plab_sz();
3050 
3051         if (should_start_conc_mark) {
3052           // We have to do this before we notify the CM threads that
3053           // they can start working to make sure that all the
3054           // appropriate initialization is done on the CM object.
3055           concurrent_mark()->post_initial_mark();
3056           // Note that we don't actually trigger the CM thread at
3057           // this point. We do that later when we're sure that
3058           // the current thread has completed its logging output.
3059         }
3060 
3061         allocate_dummy_regions();
3062 
3063         _allocator->init_mutator_alloc_region();
3064 
3065         expand_heap_after_young_collection();
3066 
3067         double sample_end_time_sec = os::elapsedTime();
3068         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3069         policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc);
3070       }
3071 
3072       verify_after_young_collection(verify_type);
3073 
3074 #ifdef TRACESPINNING
3075       ParallelTaskTerminator::print_termination_counts();
3076 #endif
3077 
3078       gc_epilogue(false);
3079     }
3080 
3081     // Print the remainder of the GC log output.
3082     if (evacuation_failed()) {
3083       log_info(gc)("To-space exhausted");
3084     }
3085 
3086     policy()->print_phases();
3087     heap_transition.print();
3088 
3089     _hrm->verify_optional();
3090     _verifier->verify_region_sets_optional();
3091 
3092     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3093     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3094 
3095     print_heap_after_gc();
3096     print_heap_regions();
3097     trace_heap_after_gc(_gc_tracer_stw);
3098 
3099     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3100     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3101     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3102     // before any GC notifications are raised.
3103     g1mm()->update_sizes();
3104 
3105     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3106     _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3107     _gc_timer_stw->register_gc_end();
3108     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3109   }
3110   // It should now be safe to tell the concurrent mark thread to start
3111   // without its logging output interfering with the logging output
3112   // that came from the pause.
3113 
3114   if (should_start_conc_mark) {
3115     // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3116     // thread(s) could be running concurrently with us. Make sure that anything
3117     // after this point does not assume that we are the only GC thread running.
3118     // Note: of course, the actual marking work will not start until the safepoint
3119     // itself is released in SuspendibleThreadSet::desynchronize().
3120     do_concurrent_mark();
3121   }
3122 
3123   return true;
3124 }
3125 
3126 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3127   G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3128   workers()->run_task(&rsfp_task);
3129 }
3130 
3131 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3132   double remove_self_forwards_start = os::elapsedTime();
3133 
3134   remove_self_forwarding_pointers(rdcqs);
3135   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3136   _preserved_marks_set.restore(&task_executor);
3137 
3138   phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3139 }
3140 
3141 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3142   if (!_evacuation_failed) {
3143     _evacuation_failed = true;
3144   }
3145 
3146   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3147   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3148 }
3149 
3150 bool G1ParEvacuateFollowersClosure::offer_termination() {
3151   EventGCPhaseParallel event;
3152   G1ParScanThreadState* const pss = par_scan_state();
3153   start_term_time();
3154   const bool res = terminator()->offer_termination();
3155   end_term_time();
3156   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3157   return res;
3158 }
3159 
3160 void G1ParEvacuateFollowersClosure::do_void() {
3161   EventGCPhaseParallel event;
3162   G1ParScanThreadState* const pss = par_scan_state();
3163   pss->trim_queue();
3164   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3165   do {
3166     EventGCPhaseParallel event;
3167     pss->steal_and_trim_queue(queues());
3168     event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3169   } while (!offer_termination());
3170 }
3171 
3172 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3173                                         bool class_unloading_occurred) {
3174   uint num_workers = workers()->active_workers();
3175   G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3176   workers()->run_task(&unlink_task);
3177 }
3178 
3179 // Clean string dedup data structures.
3180 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3181 // record the durations of the phases. Hence the almost-copy.
3182 class G1StringDedupCleaningTask : public AbstractGangTask {
3183   BoolObjectClosure* _is_alive;
3184   OopClosure* _keep_alive;
3185   G1GCPhaseTimes* _phase_times;
3186 
3187 public:
3188   G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3189                             OopClosure* keep_alive,
3190                             G1GCPhaseTimes* phase_times) :
3191     AbstractGangTask("Partial Cleaning Task"),
3192     _is_alive(is_alive),
3193     _keep_alive(keep_alive),
3194     _phase_times(phase_times)
3195   {
3196     assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3197     StringDedup::gc_prologue(true);
3198   }
3199 
3200   ~G1StringDedupCleaningTask() {
3201     StringDedup::gc_epilogue();
3202   }
3203 
3204   void work(uint worker_id) {
3205     StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3206     {
3207       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3208       StringDedupQueue::unlink_or_oops_do(&cl);
3209     }
3210     {
3211       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3212       StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3213     }
3214   }
3215 };
3216 
3217 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3218                                             OopClosure* keep_alive,
3219                                             G1GCPhaseTimes* phase_times) {
3220   G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3221   workers()->run_task(&cl);
3222 }
3223 
3224 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3225  private:
3226   G1RedirtyCardsQueueSet* _qset;
3227   G1CollectedHeap* _g1h;
3228   BufferNode* volatile _nodes;
3229 
3230   void apply(G1CardTableEntryClosure* cl, BufferNode* node, uint worker_id) {
3231     void** buf = BufferNode::make_buffer_from_node(node);
3232     size_t limit = _qset->buffer_size();
3233     for (size_t i = node->index(); i < limit; ++i) {
3234       CardTable::CardValue* card_ptr = static_cast<CardTable::CardValue*>(buf[i]);
3235       bool result = cl->do_card_ptr(card_ptr, worker_id);
3236       assert(result, "Closure should always return true");
3237     }
3238   }
3239 
3240   void par_apply(G1CardTableEntryClosure* cl, uint worker_id) {
3241     BufferNode* next = Atomic::load(&_nodes);
3242     while (next != NULL) {
3243       BufferNode* node = next;
3244       next = Atomic::cmpxchg(node->next(), &_nodes, node);
3245       if (next == node) {
3246         apply(cl, node, worker_id);
3247         next = node->next();
3248       }
3249     }
3250   }
3251 
3252  public:
3253   G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3254     AbstractGangTask("Redirty Cards"),
3255     _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3256 
3257   virtual void work(uint worker_id) {
3258     G1GCPhaseTimes* p = _g1h->phase_times();
3259     G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3260 
3261     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3262     par_apply(&cl, worker_id);
3263 
3264     p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3265   }
3266 };
3267 
3268 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3269   double redirty_logged_cards_start = os::elapsedTime();
3270 
3271   G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3272   workers()->run_task(&redirty_task);
3273 
3274   G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3275   dcq.merge_bufferlists(rdcqs);
3276 
3277   phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3278 }
3279 
3280 // Weak Reference Processing support
3281 
3282 bool G1STWIsAliveClosure::do_object_b(oop p) {
3283   // An object is reachable if it is outside the collection set,
3284   // or is inside and copied.
3285   return !_g1h->is_in_cset(p) || p->is_forwarded();
3286 }
3287 
3288 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3289   assert(obj != NULL, "must not be NULL");
3290   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3291   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3292   // may falsely indicate that this is not the case here: however the collection set only
3293   // contains old regions when concurrent mark is not running.
3294   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3295 }
3296 
3297 // Non Copying Keep Alive closure
3298 class G1KeepAliveClosure: public OopClosure {
3299   G1CollectedHeap*_g1h;
3300 public:
3301   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3302   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3303   void do_oop(oop* p) {
3304     oop obj = *p;
3305     assert(obj != NULL, "the caller should have filtered out NULL values");
3306 
3307     const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3308     if (!region_attr.is_in_cset_or_humongous()) {
3309       return;
3310     }
3311     if (region_attr.is_in_cset()) {
3312       assert( obj->is_forwarded(), "invariant" );
3313       *p = obj->forwardee();
3314     } else {
3315       assert(!obj->is_forwarded(), "invariant" );
3316       assert(region_attr.is_humongous(),
3317              "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3318      _g1h->set_humongous_is_live(obj);
3319     }
3320   }
3321 };
3322 
3323 // Copying Keep Alive closure - can be called from both
3324 // serial and parallel code as long as different worker
3325 // threads utilize different G1ParScanThreadState instances
3326 // and different queues.
3327 
3328 class G1CopyingKeepAliveClosure: public OopClosure {
3329   G1CollectedHeap*         _g1h;
3330   G1ParScanThreadState*    _par_scan_state;
3331 
3332 public:
3333   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3334                             G1ParScanThreadState* pss):
3335     _g1h(g1h),
3336     _par_scan_state(pss)
3337   {}
3338 
3339   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3340   virtual void do_oop(      oop* p) { do_oop_work(p); }
3341 
3342   template <class T> void do_oop_work(T* p) {
3343     oop obj = RawAccess<>::oop_load(p);
3344 
3345     if (_g1h->is_in_cset_or_humongous(obj)) {
3346       // If the referent object has been forwarded (either copied
3347       // to a new location or to itself in the event of an
3348       // evacuation failure) then we need to update the reference
3349       // field and, if both reference and referent are in the G1
3350       // heap, update the RSet for the referent.
3351       //
3352       // If the referent has not been forwarded then we have to keep
3353       // it alive by policy. Therefore we have copy the referent.
3354       //
3355       // When the queue is drained (after each phase of reference processing)
3356       // the object and it's followers will be copied, the reference field set
3357       // to point to the new location, and the RSet updated.
3358       _par_scan_state->push_on_queue(p);
3359     }
3360   }
3361 };
3362 
3363 // Serial drain queue closure. Called as the 'complete_gc'
3364 // closure for each discovered list in some of the
3365 // reference processing phases.
3366 
3367 class G1STWDrainQueueClosure: public VoidClosure {
3368 protected:
3369   G1CollectedHeap* _g1h;
3370   G1ParScanThreadState* _par_scan_state;
3371 
3372   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3373 
3374 public:
3375   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3376     _g1h(g1h),
3377     _par_scan_state(pss)
3378   { }
3379 
3380   void do_void() {
3381     G1ParScanThreadState* const pss = par_scan_state();
3382     pss->trim_queue();
3383   }
3384 };
3385 
3386 // Parallel Reference Processing closures
3387 
3388 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3389 // processing during G1 evacuation pauses.
3390 
3391 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3392 private:
3393   G1CollectedHeap*          _g1h;
3394   G1ParScanThreadStateSet*  _pss;
3395   RefToScanQueueSet*        _queues;
3396   WorkGang*                 _workers;
3397 
3398 public:
3399   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3400                            G1ParScanThreadStateSet* per_thread_states,
3401                            WorkGang* workers,
3402                            RefToScanQueueSet *task_queues) :
3403     _g1h(g1h),
3404     _pss(per_thread_states),
3405     _queues(task_queues),
3406     _workers(workers)
3407   {
3408     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3409   }
3410 
3411   // Executes the given task using concurrent marking worker threads.
3412   virtual void execute(ProcessTask& task, uint ergo_workers);
3413 };
3414 
3415 // Gang task for possibly parallel reference processing
3416 
3417 class G1STWRefProcTaskProxy: public AbstractGangTask {
3418   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3419   ProcessTask&     _proc_task;
3420   G1CollectedHeap* _g1h;
3421   G1ParScanThreadStateSet* _pss;
3422   RefToScanQueueSet* _task_queues;
3423   ParallelTaskTerminator* _terminator;
3424 
3425 public:
3426   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3427                         G1CollectedHeap* g1h,
3428                         G1ParScanThreadStateSet* per_thread_states,
3429                         RefToScanQueueSet *task_queues,
3430                         ParallelTaskTerminator* terminator) :
3431     AbstractGangTask("Process reference objects in parallel"),
3432     _proc_task(proc_task),
3433     _g1h(g1h),
3434     _pss(per_thread_states),
3435     _task_queues(task_queues),
3436     _terminator(terminator)
3437   {}
3438 
3439   virtual void work(uint worker_id) {
3440     // The reference processing task executed by a single worker.
3441     ResourceMark rm;
3442     HandleMark   hm;
3443 
3444     G1STWIsAliveClosure is_alive(_g1h);
3445 
3446     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3447     pss->set_ref_discoverer(NULL);
3448 
3449     // Keep alive closure.
3450     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3451 
3452     // Complete GC closure
3453     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3454 
3455     // Call the reference processing task's work routine.
3456     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3457 
3458     // Note we cannot assert that the refs array is empty here as not all
3459     // of the processing tasks (specifically phase2 - pp2_work) execute
3460     // the complete_gc closure (which ordinarily would drain the queue) so
3461     // the queue may not be empty.
3462   }
3463 };
3464 
3465 // Driver routine for parallel reference processing.
3466 // Creates an instance of the ref processing gang
3467 // task and has the worker threads execute it.
3468 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3469   assert(_workers != NULL, "Need parallel worker threads.");
3470 
3471   assert(_workers->active_workers() >= ergo_workers,
3472          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3473          ergo_workers, _workers->active_workers());
3474   TaskTerminator terminator(ergo_workers, _queues);
3475   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3476 
3477   _workers->run_task(&proc_task_proxy, ergo_workers);
3478 }
3479 
3480 // End of weak reference support closures
3481 
3482 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3483   double ref_proc_start = os::elapsedTime();
3484 
3485   ReferenceProcessor* rp = _ref_processor_stw;
3486   assert(rp->discovery_enabled(), "should have been enabled");
3487 
3488   // Closure to test whether a referent is alive.
3489   G1STWIsAliveClosure is_alive(this);
3490 
3491   // Even when parallel reference processing is enabled, the processing
3492   // of JNI refs is serial and performed serially by the current thread
3493   // rather than by a worker. The following PSS will be used for processing
3494   // JNI refs.
3495 
3496   // Use only a single queue for this PSS.
3497   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3498   pss->set_ref_discoverer(NULL);
3499   assert(pss->queue_is_empty(), "pre-condition");
3500 
3501   // Keep alive closure.
3502   G1CopyingKeepAliveClosure keep_alive(this, pss);
3503 
3504   // Serial Complete GC closure
3505   G1STWDrainQueueClosure drain_queue(this, pss);
3506 
3507   // Setup the soft refs policy...
3508   rp->setup_policy(false);
3509 
3510   ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3511 
3512   ReferenceProcessorStats stats;
3513   if (!rp->processing_is_mt()) {
3514     // Serial reference processing...
3515     stats = rp->process_discovered_references(&is_alive,
3516                                               &keep_alive,
3517                                               &drain_queue,
3518                                               NULL,
3519                                               pt);
3520   } else {
3521     uint no_of_gc_workers = workers()->active_workers();
3522 
3523     // Parallel reference processing
3524     assert(no_of_gc_workers <= rp->max_num_queues(),
3525            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3526            no_of_gc_workers,  rp->max_num_queues());
3527 
3528     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3529     stats = rp->process_discovered_references(&is_alive,
3530                                               &keep_alive,
3531                                               &drain_queue,
3532                                               &par_task_executor,
3533                                               pt);
3534   }
3535 
3536   _gc_tracer_stw->report_gc_reference_stats(stats);
3537 
3538   // We have completed copying any necessary live referent objects.
3539   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3540 
3541   make_pending_list_reachable();
3542 
3543   assert(!rp->discovery_enabled(), "Postcondition");
3544   rp->verify_no_references_recorded();
3545 
3546   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3547   phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3548 }
3549 
3550 void G1CollectedHeap::make_pending_list_reachable() {
3551   if (collector_state()->in_initial_mark_gc()) {
3552     oop pll_head = Universe::reference_pending_list();
3553     if (pll_head != NULL) {
3554       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3555       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3556     }
3557   }
3558 }
3559 
3560 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3561   double merge_pss_time_start = os::elapsedTime();
3562   per_thread_states->flush();
3563   phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3564 }
3565 
3566 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3567   _expand_heap_after_alloc_failure = true;
3568   _evacuation_failed = false;
3569 
3570   // Disable the hot card cache.
3571   _hot_card_cache->reset_hot_cache_claimed_index();
3572   _hot_card_cache->set_use_cache(false);
3573 
3574   // Initialize the GC alloc regions.
3575   _allocator->init_gc_alloc_regions(evacuation_info);
3576 
3577   {
3578     Ticks start = Ticks::now();
3579     rem_set()->prepare_for_scan_heap_roots();
3580     phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3581   }
3582 
3583   register_regions_with_region_attr();
3584   assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3585 
3586   _preserved_marks_set.assert_empty();
3587 
3588 #if COMPILER2_OR_JVMCI
3589   DerivedPointerTable::clear();
3590 #endif
3591 
3592   // InitialMark needs claim bits to keep track of the marked-through CLDs.
3593   if (collector_state()->in_initial_mark_gc()) {
3594     concurrent_mark()->pre_initial_mark();
3595 
3596     double start_clear_claimed_marks = os::elapsedTime();
3597 
3598     ClassLoaderDataGraph::clear_claimed_marks();
3599 
3600     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3601     phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3602   }
3603 
3604   // Should G1EvacuationFailureALot be in effect for this GC?
3605   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3606 }
3607 
3608 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3609 protected:
3610   G1CollectedHeap* _g1h;
3611   G1ParScanThreadStateSet* _per_thread_states;
3612   RefToScanQueueSet* _task_queues;
3613   TaskTerminator _terminator;
3614   uint _num_workers;
3615 
3616   void evacuate_live_objects(G1ParScanThreadState* pss,
3617                              uint worker_id,
3618                              G1GCPhaseTimes::GCParPhases objcopy_phase,
3619                              G1GCPhaseTimes::GCParPhases termination_phase) {
3620     G1GCPhaseTimes* p = _g1h->phase_times();
3621 
3622     Ticks start = Ticks::now();
3623     G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3624     cl.do_void();
3625 
3626     assert(pss->queue_is_empty(), "should be empty");
3627 
3628     Tickspan evac_time = (Ticks::now() - start);
3629     p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3630 
3631     p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste);
3632     p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste);
3633 
3634     if (termination_phase == G1GCPhaseTimes::Termination) {
3635       p->record_time_secs(termination_phase, worker_id, cl.term_time());
3636       p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3637     } else {
3638       p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3639       p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3640     }
3641     assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3642   }
3643 
3644   virtual void start_work(uint worker_id) { }
3645 
3646   virtual void end_work(uint worker_id) { }
3647 
3648   virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3649 
3650   virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3651 
3652 public:
3653   G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3654     AbstractGangTask(name),
3655     _g1h(G1CollectedHeap::heap()),
3656     _per_thread_states(per_thread_states),
3657     _task_queues(task_queues),
3658     _terminator(num_workers, _task_queues),
3659     _num_workers(num_workers)
3660   { }
3661 
3662   void work(uint worker_id) {
3663     start_work(worker_id);
3664 
3665     {
3666       ResourceMark rm;
3667       HandleMark   hm;
3668 
3669       G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3670       pss->set_ref_discoverer(_g1h->ref_processor_stw());
3671 
3672       scan_roots(pss, worker_id);
3673       evacuate_live_objects(pss, worker_id);
3674     }
3675 
3676     end_work(worker_id);
3677   }
3678 };
3679 
3680 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3681   G1RootProcessor* _root_processor;
3682 
3683   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3684     _root_processor->evacuate_roots(pss, worker_id);
3685     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3686     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3687   }
3688 
3689   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3690     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3691   }
3692 
3693   void start_work(uint worker_id) {
3694     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3695   }
3696 
3697   void end_work(uint worker_id) {
3698     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3699   }
3700 
3701 public:
3702   G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3703                         G1ParScanThreadStateSet* per_thread_states,
3704                         RefToScanQueueSet* task_queues,
3705                         G1RootProcessor* root_processor,
3706                         uint num_workers) :
3707     G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3708     _root_processor(root_processor)
3709   { }
3710 };
3711 
3712 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3713   G1GCPhaseTimes* p = phase_times();
3714 
3715   {
3716     Ticks start = Ticks::now();
3717     rem_set()->merge_heap_roots(true /* initial_evacuation */);
3718     p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3719   }
3720 
3721   Tickspan task_time;
3722   const uint num_workers = workers()->active_workers();
3723 
3724   Ticks start_processing = Ticks::now();
3725   {
3726     G1RootProcessor root_processor(this, num_workers);
3727     G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3728     task_time = run_task(&g1_par_task);
3729     // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3730     // To extract its code root fixup time we measure total time of this scope and
3731     // subtract from the time the WorkGang task took.
3732   }
3733   Tickspan total_processing = Ticks::now() - start_processing;
3734 
3735   p->record_initial_evac_time(task_time.seconds() * 1000.0);
3736   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3737 }
3738 
3739 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3740 
3741   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3742     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3743     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3744   }
3745 
3746   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3747     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3748   }
3749 
3750 public:
3751   G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3752                                 RefToScanQueueSet* queues,
3753                                 uint num_workers) :
3754     G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3755   }
3756 };
3757 
3758 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3759   class G1MarkScope : public MarkScope { };
3760 
3761   Tickspan task_time;
3762 
3763   Ticks start_processing = Ticks::now();
3764   {
3765     G1MarkScope code_mark_scope;
3766     G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3767     task_time = run_task(&task);
3768     // See comment in evacuate_collection_set() for the reason of the scope.
3769   }
3770   Tickspan total_processing = Ticks::now() - start_processing;
3771 
3772   G1GCPhaseTimes* p = phase_times();
3773   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3774 }
3775 
3776 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3777   const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3778 
3779   while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3780 
3781     double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3782     double time_left_ms = MaxGCPauseMillis - time_used_ms;
3783 
3784     if (time_left_ms < 0 ||
3785         !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3786       log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3787                                 _collection_set.optional_region_length(), time_left_ms);
3788       break;
3789     }
3790 
3791     {
3792       Ticks start = Ticks::now();
3793       rem_set()->merge_heap_roots(false /* initial_evacuation */);
3794       phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3795     }
3796 
3797     {
3798       Ticks start = Ticks::now();
3799       evacuate_next_optional_regions(per_thread_states);
3800       phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3801     }
3802   }
3803 
3804   _collection_set.abandon_optional_collection_set(per_thread_states);
3805 }
3806 
3807 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3808                                                    G1RedirtyCardsQueueSet* rdcqs,
3809                                                    G1ParScanThreadStateSet* per_thread_states) {
3810   rem_set()->cleanup_after_scan_heap_roots();
3811 
3812   // Process any discovered reference objects - we have
3813   // to do this _before_ we retire the GC alloc regions
3814   // as we may have to copy some 'reachable' referent
3815   // objects (and their reachable sub-graphs) that were
3816   // not copied during the pause.
3817   process_discovered_references(per_thread_states);
3818 
3819   G1STWIsAliveClosure is_alive(this);
3820   G1KeepAliveClosure keep_alive(this);
3821 
3822   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3823                               phase_times()->weak_phase_times());
3824 
3825   if (G1StringDedup::is_enabled()) {
3826     double string_dedup_time_ms = os::elapsedTime();
3827 
3828     string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
3829 
3830     double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3831     phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3832   }
3833 
3834   _allocator->release_gc_alloc_regions(evacuation_info);
3835 
3836   if (evacuation_failed()) {
3837     restore_after_evac_failure(rdcqs);
3838 
3839     // Reset the G1EvacuationFailureALot counters and flags
3840     NOT_PRODUCT(reset_evacuation_should_fail();)
3841 
3842     double recalculate_used_start = os::elapsedTime();
3843     set_used(recalculate_used());
3844     phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3845 
3846     if (_archive_allocator != NULL) {
3847       _archive_allocator->clear_used();
3848     }
3849     for (uint i = 0; i < ParallelGCThreads; i++) {
3850       if (_evacuation_failed_info_array[i].has_failed()) {
3851         _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3852       }
3853     }
3854   } else {
3855     // The "used" of the the collection set have already been subtracted
3856     // when they were freed.  Add in the bytes evacuated.
3857     increase_used(policy()->bytes_copied_during_gc());
3858   }
3859 
3860   _preserved_marks_set.assert_empty();
3861 
3862   merge_per_thread_state_info(per_thread_states);
3863 
3864   // Reset and re-enable the hot card cache.
3865   // Note the counts for the cards in the regions in the
3866   // collection set are reset when the collection set is freed.
3867   _hot_card_cache->reset_hot_cache();
3868   _hot_card_cache->set_use_cache(true);
3869 
3870   purge_code_root_memory();
3871 
3872   redirty_logged_cards(rdcqs);
3873 
3874   free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3875 
3876   eagerly_reclaim_humongous_regions();
3877 
3878   record_obj_copy_mem_stats();
3879 
3880   evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3881   evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
3882 
3883 #if COMPILER2_OR_JVMCI
3884   double start = os::elapsedTime();
3885   DerivedPointerTable::update_pointers();
3886   phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3887 #endif
3888   policy()->print_age_table();
3889 }
3890 
3891 void G1CollectedHeap::record_obj_copy_mem_stats() {
3892   policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3893 
3894   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3895                                                create_g1_evac_summary(&_old_evac_stats));
3896 }
3897 
3898 void G1CollectedHeap::free_region(HeapRegion* hr,
3899                                   FreeRegionList* free_list,
3900                                   bool skip_remset,
3901                                   bool skip_hot_card_cache,
3902                                   bool locked) {
3903   assert(!hr->is_free(), "the region should not be free");
3904   assert(!hr->is_empty(), "the region should not be empty");
3905   assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3906   assert(free_list != NULL, "pre-condition");
3907 
3908   if (G1VerifyBitmaps) {
3909     MemRegion mr(hr->bottom(), hr->end());
3910     concurrent_mark()->clear_range_in_prev_bitmap(mr);
3911   }
3912 
3913   // Clear the card counts for this region.
3914   // Note: we only need to do this if the region is not young
3915   // (since we don't refine cards in young regions).
3916   if (!skip_hot_card_cache && !hr->is_young()) {
3917     _hot_card_cache->reset_card_counts(hr);
3918   }
3919   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3920   _policy->remset_tracker()->update_at_free(hr);
3921   free_list->add_ordered(hr);
3922 }
3923 
3924 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3925                                             FreeRegionList* free_list) {
3926   assert(hr->is_humongous(), "this is only for humongous regions");
3927   assert(free_list != NULL, "pre-condition");
3928   hr->clear_humongous();
3929   free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3930 }
3931 
3932 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3933                                            const uint humongous_regions_removed) {
3934   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3935     MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3936     _old_set.bulk_remove(old_regions_removed);
3937     _humongous_set.bulk_remove(humongous_regions_removed);
3938   }
3939 
3940 }
3941 
3942 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3943   assert(list != NULL, "list can't be null");
3944   if (!list->is_empty()) {
3945     MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3946     _hrm->insert_list_into_free_list(list);
3947   }
3948 }
3949 
3950 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3951   decrease_used(bytes);
3952 }
3953 
3954 class G1FreeCollectionSetTask : public AbstractGangTask {
3955 private:
3956 
3957   // Closure applied to all regions in the collection set to do work that needs to
3958   // be done serially in a single thread.
3959   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3960   private:
3961     G1EvacuationInfo* _evacuation_info;
3962     const size_t* _surviving_young_words;
3963 
3964     // Bytes used in successfully evacuated regions before the evacuation.
3965     size_t _before_used_bytes;
3966     // Bytes used in unsucessfully evacuated regions before the evacuation
3967     size_t _after_used_bytes;
3968 
3969     size_t _bytes_allocated_in_old_since_last_gc;
3970 
3971     size_t _failure_used_words;
3972     size_t _failure_waste_words;
3973 
3974     FreeRegionList _local_free_list;
3975   public:
3976     G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3977       HeapRegionClosure(),
3978       _evacuation_info(evacuation_info),
3979       _surviving_young_words(surviving_young_words),
3980       _before_used_bytes(0),
3981       _after_used_bytes(0),
3982       _bytes_allocated_in_old_since_last_gc(0),
3983       _failure_used_words(0),
3984       _failure_waste_words(0),
3985       _local_free_list("Local Region List for CSet Freeing") {
3986     }
3987 
3988     virtual bool do_heap_region(HeapRegion* r) {
3989       G1CollectedHeap* g1h = G1CollectedHeap::heap();
3990 
3991       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3992       g1h->clear_region_attr(r);
3993 
3994       if (r->is_young()) {
3995         assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(),
3996                "Young index %u is wrong for region %u of type %s with %u young regions",
3997                r->young_index_in_cset(),
3998                r->hrm_index(),
3999                r->get_type_str(),
4000                g1h->collection_set()->young_region_length());
4001         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4002         r->record_surv_words_in_group(words_survived);
4003       }
4004 
4005       if (!r->evacuation_failed()) {
4006         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4007         _before_used_bytes += r->used();
4008         g1h->free_region(r,
4009                          &_local_free_list,
4010                          true, /* skip_remset */
4011                          true, /* skip_hot_card_cache */
4012                          true  /* locked */);
4013       } else {
4014         r->uninstall_surv_rate_group();
4015         r->clear_young_index_in_cset();
4016         r->set_evacuation_failed(false);
4017         // When moving a young gen region to old gen, we "allocate" that whole region
4018         // there. This is in addition to any already evacuated objects. Notify the
4019         // policy about that.
4020         // Old gen regions do not cause an additional allocation: both the objects
4021         // still in the region and the ones already moved are accounted for elsewhere.
4022         if (r->is_young()) {
4023           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4024         }
4025         // The region is now considered to be old.
4026         r->set_old();
4027         // Do some allocation statistics accounting. Regions that failed evacuation
4028         // are always made old, so there is no need to update anything in the young
4029         // gen statistics, but we need to update old gen statistics.
4030         size_t used_words = r->marked_bytes() / HeapWordSize;
4031 
4032         _failure_used_words += used_words;
4033         _failure_waste_words += HeapRegion::GrainWords - used_words;
4034 
4035         g1h->old_set_add(r);
4036         _after_used_bytes += r->used();
4037       }
4038       return false;
4039     }
4040 
4041     void complete_work() {
4042       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4043 
4044       _evacuation_info->set_regions_freed(_local_free_list.length());
4045       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4046 
4047       g1h->prepend_to_freelist(&_local_free_list);
4048       g1h->decrement_summary_bytes(_before_used_bytes);
4049 
4050       G1Policy* policy = g1h->policy();
4051       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4052 
4053       g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4054     }
4055   };
4056 
4057   G1CollectionSet* _collection_set;
4058   G1SerialFreeCollectionSetClosure _cl;
4059   const size_t* _surviving_young_words;
4060 
4061   size_t _rs_length;
4062 
4063   volatile jint _serial_work_claim;
4064 
4065   struct WorkItem {
4066     uint region_idx;
4067     bool is_young;
4068     bool evacuation_failed;
4069 
4070     WorkItem(HeapRegion* r) {
4071       region_idx = r->hrm_index();
4072       is_young = r->is_young();
4073       evacuation_failed = r->evacuation_failed();
4074     }
4075   };
4076 
4077   volatile size_t _parallel_work_claim;
4078   size_t _num_work_items;
4079   WorkItem* _work_items;
4080 
4081   void do_serial_work() {
4082     // Need to grab the lock to be allowed to modify the old region list.
4083     MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4084     _collection_set->iterate(&_cl);
4085   }
4086 
4087   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4088     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4089 
4090     HeapRegion* r = g1h->region_at(region_idx);
4091     assert(!g1h->is_on_master_free_list(r), "sanity");
4092 
4093     Atomic::add(r->rem_set()->occupied_locked(), &_rs_length);
4094 
4095     if (!is_young) {
4096       g1h->_hot_card_cache->reset_card_counts(r);
4097     }
4098 
4099     if (!evacuation_failed) {
4100       r->rem_set()->clear_locked();
4101     }
4102   }
4103 
4104   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4105   private:
4106     size_t _cur_idx;
4107     WorkItem* _work_items;
4108   public:
4109     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4110 
4111     virtual bool do_heap_region(HeapRegion* r) {
4112       _work_items[_cur_idx++] = WorkItem(r);
4113       return false;
4114     }
4115   };
4116 
4117   void prepare_work() {
4118     G1PrepareFreeCollectionSetClosure cl(_work_items);
4119     _collection_set->iterate(&cl);
4120   }
4121 
4122   void complete_work() {
4123     _cl.complete_work();
4124 
4125     G1Policy* policy = G1CollectedHeap::heap()->policy();
4126     policy->record_max_rs_length(_rs_length);
4127     policy->cset_regions_freed();
4128   }
4129 public:
4130   G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4131     AbstractGangTask("G1 Free Collection Set"),
4132     _collection_set(collection_set),
4133     _cl(evacuation_info, surviving_young_words),
4134     _surviving_young_words(surviving_young_words),
4135     _rs_length(0),
4136     _serial_work_claim(0),
4137     _parallel_work_claim(0),
4138     _num_work_items(collection_set->region_length()),
4139     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4140     prepare_work();
4141   }
4142 
4143   ~G1FreeCollectionSetTask() {
4144     complete_work();
4145     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4146   }
4147 
4148   // Chunk size for work distribution. The chosen value has been determined experimentally
4149   // to be a good tradeoff between overhead and achievable parallelism.
4150   static uint chunk_size() { return 32; }
4151 
4152   virtual void work(uint worker_id) {
4153     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4154 
4155     // Claim serial work.
4156     if (_serial_work_claim == 0) {
4157       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4158       if (value == 0) {
4159         double serial_time = os::elapsedTime();
4160         do_serial_work();
4161         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4162       }
4163     }
4164 
4165     // Start parallel work.
4166     double young_time = 0.0;
4167     bool has_young_time = false;
4168     double non_young_time = 0.0;
4169     bool has_non_young_time = false;
4170 
4171     while (true) {
4172       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4173       size_t cur = end - chunk_size();
4174 
4175       if (cur >= _num_work_items) {
4176         break;
4177       }
4178 
4179       EventGCPhaseParallel event;
4180       double start_time = os::elapsedTime();
4181 
4182       end = MIN2(end, _num_work_items);
4183 
4184       for (; cur < end; cur++) {
4185         bool is_young = _work_items[cur].is_young;
4186 
4187         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4188 
4189         double end_time = os::elapsedTime();
4190         double time_taken = end_time - start_time;
4191         if (is_young) {
4192           young_time += time_taken;
4193           has_young_time = true;
4194           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4195         } else {
4196           non_young_time += time_taken;
4197           has_non_young_time = true;
4198           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4199         }
4200         start_time = end_time;
4201       }
4202     }
4203 
4204     if (has_young_time) {
4205       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4206     }
4207     if (has_non_young_time) {
4208       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4209     }
4210   }
4211 };
4212 
4213 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4214   _eden.clear();
4215 
4216   double free_cset_start_time = os::elapsedTime();
4217 
4218   {
4219     uint const num_regions = _collection_set.region_length();
4220     uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U);
4221     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4222 
4223     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4224 
4225     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4226                         cl.name(), num_workers, num_regions);
4227     workers()->run_task(&cl, num_workers);
4228   }
4229   phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4230 
4231   collection_set->clear();
4232 }
4233 
4234 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4235  private:
4236   FreeRegionList* _free_region_list;
4237   HeapRegionSet* _proxy_set;
4238   uint _humongous_objects_reclaimed;
4239   uint _humongous_regions_reclaimed;
4240   size_t _freed_bytes;
4241  public:
4242 
4243   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4244     _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4245   }
4246 
4247   virtual bool do_heap_region(HeapRegion* r) {
4248     if (!r->is_starts_humongous()) {
4249       return false;
4250     }
4251 
4252     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4253 
4254     oop obj = (oop)r->bottom();
4255     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4256 
4257     // The following checks whether the humongous object is live are sufficient.
4258     // The main additional check (in addition to having a reference from the roots
4259     // or the young gen) is whether the humongous object has a remembered set entry.
4260     //
4261     // A humongous object cannot be live if there is no remembered set for it
4262     // because:
4263     // - there can be no references from within humongous starts regions referencing
4264     // the object because we never allocate other objects into them.
4265     // (I.e. there are no intra-region references that may be missed by the
4266     // remembered set)
4267     // - as soon there is a remembered set entry to the humongous starts region
4268     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4269     // until the end of a concurrent mark.
4270     //
4271     // It is not required to check whether the object has been found dead by marking
4272     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4273     // all objects allocated during that time are considered live.
4274     // SATB marking is even more conservative than the remembered set.
4275     // So if at this point in the collection there is no remembered set entry,
4276     // nobody has a reference to it.
4277     // At the start of collection we flush all refinement logs, and remembered sets
4278     // are completely up-to-date wrt to references to the humongous object.
4279     //
4280     // Other implementation considerations:
4281     // - never consider object arrays at this time because they would pose
4282     // considerable effort for cleaning up the the remembered sets. This is
4283     // required because stale remembered sets might reference locations that
4284     // are currently allocated into.
4285     uint region_idx = r->hrm_index();
4286     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4287         !r->rem_set()->is_empty()) {
4288       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",
4289                                region_idx,
4290                                (size_t)obj->size() * HeapWordSize,
4291                                p2i(r->bottom()),
4292                                r->rem_set()->occupied(),
4293                                r->rem_set()->strong_code_roots_list_length(),
4294                                next_bitmap->is_marked(r->bottom()),
4295                                g1h->is_humongous_reclaim_candidate(region_idx),
4296                                obj->is_typeArray()
4297                               );
4298       return false;
4299     }
4300 
4301     guarantee(obj->is_typeArray(),
4302               "Only eagerly reclaiming type arrays is supported, but the object "
4303               PTR_FORMAT " is not.", p2i(r->bottom()));
4304 
4305     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",
4306                              region_idx,
4307                              (size_t)obj->size() * HeapWordSize,
4308                              p2i(r->bottom()),
4309                              r->rem_set()->occupied(),
4310                              r->rem_set()->strong_code_roots_list_length(),
4311                              next_bitmap->is_marked(r->bottom()),
4312                              g1h->is_humongous_reclaim_candidate(region_idx),
4313                              obj->is_typeArray()
4314                             );
4315 
4316     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4317     cm->humongous_object_eagerly_reclaimed(r);
4318     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4319            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4320            region_idx,
4321            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4322            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4323     _humongous_objects_reclaimed++;
4324     do {
4325       HeapRegion* next = g1h->next_region_in_humongous(r);
4326       _freed_bytes += r->used();
4327       r->set_containing_set(NULL);
4328       _humongous_regions_reclaimed++;
4329       g1h->free_humongous_region(r, _free_region_list);
4330       r = next;
4331     } while (r != NULL);
4332 
4333     return false;
4334   }
4335 
4336   uint humongous_objects_reclaimed() {
4337     return _humongous_objects_reclaimed;
4338   }
4339 
4340   uint humongous_regions_reclaimed() {
4341     return _humongous_regions_reclaimed;
4342   }
4343 
4344   size_t bytes_freed() const {
4345     return _freed_bytes;
4346   }
4347 };
4348 
4349 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4350   assert_at_safepoint_on_vm_thread();
4351 
4352   if (!G1EagerReclaimHumongousObjects ||
4353       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4354     phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4355     return;
4356   }
4357 
4358   double start_time = os::elapsedTime();
4359 
4360   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4361 
4362   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4363   heap_region_iterate(&cl);
4364 
4365   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4366 
4367   G1HRPrinter* hrp = hr_printer();
4368   if (hrp->is_active()) {
4369     FreeRegionListIterator iter(&local_cleanup_list);
4370     while (iter.more_available()) {
4371       HeapRegion* hr = iter.get_next();
4372       hrp->cleanup(hr);
4373     }
4374   }
4375 
4376   prepend_to_freelist(&local_cleanup_list);
4377   decrement_summary_bytes(cl.bytes_freed());
4378 
4379   phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4380                                                        cl.humongous_objects_reclaimed());
4381 }
4382 
4383 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4384 public:
4385   virtual bool do_heap_region(HeapRegion* r) {
4386     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4387     G1CollectedHeap::heap()->clear_region_attr(r);
4388     r->clear_young_index_in_cset();
4389     return false;
4390   }
4391 };
4392 
4393 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4394   G1AbandonCollectionSetClosure cl;
4395   collection_set_iterate_all(&cl);
4396 
4397   collection_set->clear();
4398   collection_set->stop_incremental_building();
4399 }
4400 
4401 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4402   return _allocator->is_retained_old_region(hr);
4403 }
4404 
4405 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4406   _eden.add(hr);
4407   _policy->set_region_eden(hr);
4408 }
4409 
4410 #ifdef ASSERT
4411 
4412 class NoYoungRegionsClosure: public HeapRegionClosure {
4413 private:
4414   bool _success;
4415 public:
4416   NoYoungRegionsClosure() : _success(true) { }
4417   bool do_heap_region(HeapRegion* r) {
4418     if (r->is_young()) {
4419       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4420                             p2i(r->bottom()), p2i(r->end()));
4421       _success = false;
4422     }
4423     return false;
4424   }
4425   bool success() { return _success; }
4426 };
4427 
4428 bool G1CollectedHeap::check_young_list_empty() {
4429   bool ret = (young_regions_count() == 0);
4430 
4431   NoYoungRegionsClosure closure;
4432   heap_region_iterate(&closure);
4433   ret = ret && closure.success();
4434 
4435   return ret;
4436 }
4437 
4438 #endif // ASSERT
4439 
4440 class TearDownRegionSetsClosure : public HeapRegionClosure {
4441   HeapRegionSet *_old_set;
4442 
4443 public:
4444   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4445 
4446   bool do_heap_region(HeapRegion* r) {
4447     if (r->is_old()) {
4448       _old_set->remove(r);
4449     } else if(r->is_young()) {
4450       r->uninstall_surv_rate_group();
4451     } else {
4452       // We ignore free regions, we'll empty the free list afterwards.
4453       // We ignore humongous and archive regions, we're not tearing down these
4454       // sets.
4455       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4456              "it cannot be another type");
4457     }
4458     return false;
4459   }
4460 
4461   ~TearDownRegionSetsClosure() {
4462     assert(_old_set->is_empty(), "post-condition");
4463   }
4464 };
4465 
4466 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4467   assert_at_safepoint_on_vm_thread();
4468 
4469   if (!free_list_only) {
4470     TearDownRegionSetsClosure cl(&_old_set);
4471     heap_region_iterate(&cl);
4472 
4473     // Note that emptying the _young_list is postponed and instead done as
4474     // the first step when rebuilding the regions sets again. The reason for
4475     // this is that during a full GC string deduplication needs to know if
4476     // a collected region was young or old when the full GC was initiated.
4477   }
4478   _hrm->remove_all_free_regions();
4479 }
4480 
4481 void G1CollectedHeap::increase_used(size_t bytes) {
4482   _summary_bytes_used += bytes;
4483 }
4484 
4485 void G1CollectedHeap::decrease_used(size_t bytes) {
4486   assert(_summary_bytes_used >= bytes,
4487          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4488          _summary_bytes_used, bytes);
4489   _summary_bytes_used -= bytes;
4490 }
4491 
4492 void G1CollectedHeap::set_used(size_t bytes) {
4493   _summary_bytes_used = bytes;
4494 }
4495 
4496 class RebuildRegionSetsClosure : public HeapRegionClosure {
4497 private:
4498   bool _free_list_only;
4499 
4500   HeapRegionSet* _old_set;
4501   HeapRegionManager* _hrm;
4502 
4503   size_t _total_used;
4504 
4505 public:
4506   RebuildRegionSetsClosure(bool free_list_only,
4507                            HeapRegionSet* old_set,
4508                            HeapRegionManager* hrm) :
4509     _free_list_only(free_list_only),
4510     _old_set(old_set), _hrm(hrm), _total_used(0) {
4511     assert(_hrm->num_free_regions() == 0, "pre-condition");
4512     if (!free_list_only) {
4513       assert(_old_set->is_empty(), "pre-condition");
4514     }
4515   }
4516 
4517   bool do_heap_region(HeapRegion* r) {
4518     if (r->is_empty()) {
4519       assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4520       // Add free regions to the free list
4521       r->set_free();
4522       _hrm->insert_into_free_list(r);
4523     } else if (!_free_list_only) {
4524       assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4525 
4526       if (r->is_archive() || r->is_humongous()) {
4527         // We ignore archive and humongous regions. We left these sets unchanged.
4528       } else {
4529         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4530         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4531         r->move_to_old();
4532         _old_set->add(r);
4533       }
4534       _total_used += r->used();
4535     }
4536 
4537     return false;
4538   }
4539 
4540   size_t total_used() {
4541     return _total_used;
4542   }
4543 };
4544 
4545 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4546   assert_at_safepoint_on_vm_thread();
4547 
4548   if (!free_list_only) {
4549     _eden.clear();
4550     _survivor.clear();
4551   }
4552 
4553   RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4554   heap_region_iterate(&cl);
4555 
4556   if (!free_list_only) {
4557     set_used(cl.total_used());
4558     if (_archive_allocator != NULL) {
4559       _archive_allocator->clear_used();
4560     }
4561   }
4562   assert_used_and_recalculate_used_equal(this);
4563 }
4564 
4565 // Methods for the mutator alloc region
4566 
4567 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4568                                                       bool force) {
4569   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4570   bool should_allocate = policy()->should_allocate_mutator_region();
4571   if (force || should_allocate) {
4572     HeapRegion* new_alloc_region = new_region(word_size,
4573                                               HeapRegionType::Eden,
4574                                               false /* do_expand */);
4575     if (new_alloc_region != NULL) {
4576       set_region_short_lived_locked(new_alloc_region);
4577       _hr_printer.alloc(new_alloc_region, !should_allocate);
4578       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4579       _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4580       return new_alloc_region;
4581     }
4582   }
4583   return NULL;
4584 }
4585 
4586 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4587                                                   size_t allocated_bytes) {
4588   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4589   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4590 
4591   collection_set()->add_eden_region(alloc_region);
4592   increase_used(allocated_bytes);
4593   _eden.add_used_bytes(allocated_bytes);
4594   _hr_printer.retire(alloc_region);
4595 
4596   // We update the eden sizes here, when the region is retired,
4597   // instead of when it's allocated, since this is the point that its
4598   // used space has been recorded in _summary_bytes_used.
4599   g1mm()->update_eden_size();
4600 }
4601 
4602 // Methods for the GC alloc regions
4603 
4604 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4605   if (dest.is_old()) {
4606     return true;
4607   } else {
4608     return survivor_regions_count() < policy()->max_survivor_regions();
4609   }
4610 }
4611 
4612 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest) {
4613   assert(FreeList_lock->owned_by_self(), "pre-condition");
4614 
4615   if (!has_more_regions(dest)) {
4616     return NULL;
4617   }
4618 
4619   HeapRegionType type;
4620   if (dest.is_young()) {
4621     type = HeapRegionType::Survivor;
4622   } else {
4623     type = HeapRegionType::Old;
4624   }
4625 
4626   HeapRegion* new_alloc_region = new_region(word_size,
4627                                             type,
4628                                             true /* do_expand */);
4629 
4630   if (new_alloc_region != NULL) {
4631     if (type.is_survivor()) {
4632       new_alloc_region->set_survivor();
4633       _survivor.add(new_alloc_region);
4634       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4635     } else {
4636       new_alloc_region->set_old();
4637       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4638     }
4639     _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4640     register_region_with_region_attr(new_alloc_region);
4641     _hr_printer.alloc(new_alloc_region);
4642     return new_alloc_region;
4643   }
4644   return NULL;
4645 }
4646 
4647 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4648                                              size_t allocated_bytes,
4649                                              G1HeapRegionAttr dest) {
4650   policy()->record_bytes_copied_during_gc(allocated_bytes);
4651   if (dest.is_old()) {
4652     old_set_add(alloc_region);
4653   } else {
4654     assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4655     _survivor.add_used_bytes(allocated_bytes);
4656   }
4657 
4658   bool const during_im = collector_state()->in_initial_mark_gc();
4659   if (during_im && allocated_bytes > 0) {
4660     _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4661   }
4662   _hr_printer.retire(alloc_region);
4663 }
4664 
4665 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4666   bool expanded = false;
4667   uint index = _hrm->find_highest_free(&expanded);
4668 
4669   if (index != G1_NO_HRM_INDEX) {
4670     if (expanded) {
4671       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4672                                 HeapRegion::GrainWords * HeapWordSize);
4673     }
4674     _hrm->allocate_free_regions_starting_at(index, 1);
4675     return region_at(index);
4676   }
4677   return NULL;
4678 }
4679 
4680 // Optimized nmethod scanning
4681 
4682 class RegisterNMethodOopClosure: public OopClosure {
4683   G1CollectedHeap* _g1h;
4684   nmethod* _nm;
4685 
4686   template <class T> void do_oop_work(T* p) {
4687     T heap_oop = RawAccess<>::oop_load(p);
4688     if (!CompressedOops::is_null(heap_oop)) {
4689       oop obj = CompressedOops::decode_not_null(heap_oop);
4690       HeapRegion* hr = _g1h->heap_region_containing(obj);
4691       assert(!hr->is_continues_humongous(),
4692              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4693              " starting at " HR_FORMAT,
4694              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4695 
4696       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4697       hr->add_strong_code_root_locked(_nm);
4698     }
4699   }
4700 
4701 public:
4702   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4703     _g1h(g1h), _nm(nm) {}
4704 
4705   void do_oop(oop* p)       { do_oop_work(p); }
4706   void do_oop(narrowOop* p) { do_oop_work(p); }
4707 };
4708 
4709 class UnregisterNMethodOopClosure: public OopClosure {
4710   G1CollectedHeap* _g1h;
4711   nmethod* _nm;
4712 
4713   template <class T> void do_oop_work(T* p) {
4714     T heap_oop = RawAccess<>::oop_load(p);
4715     if (!CompressedOops::is_null(heap_oop)) {
4716       oop obj = CompressedOops::decode_not_null(heap_oop);
4717       HeapRegion* hr = _g1h->heap_region_containing(obj);
4718       assert(!hr->is_continues_humongous(),
4719              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4720              " starting at " HR_FORMAT,
4721              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4722 
4723       hr->remove_strong_code_root(_nm);
4724     }
4725   }
4726 
4727 public:
4728   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4729     _g1h(g1h), _nm(nm) {}
4730 
4731   void do_oop(oop* p)       { do_oop_work(p); }
4732   void do_oop(narrowOop* p) { do_oop_work(p); }
4733 };
4734 
4735 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4736   guarantee(nm != NULL, "sanity");
4737   RegisterNMethodOopClosure reg_cl(this, nm);
4738   nm->oops_do(&reg_cl);
4739 }
4740 
4741 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4742   guarantee(nm != NULL, "sanity");
4743   UnregisterNMethodOopClosure reg_cl(this, nm);
4744   nm->oops_do(&reg_cl, true);
4745 }
4746 
4747 void G1CollectedHeap::purge_code_root_memory() {
4748   double purge_start = os::elapsedTime();
4749   G1CodeRootSet::purge();
4750   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4751   phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4752 }
4753 
4754 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4755   G1CollectedHeap* _g1h;
4756 
4757 public:
4758   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4759     _g1h(g1h) {}
4760 
4761   void do_code_blob(CodeBlob* cb) {
4762     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4763     if (nm == NULL) {
4764       return;
4765     }
4766 
4767     _g1h->register_nmethod(nm);
4768   }
4769 };
4770 
4771 void G1CollectedHeap::rebuild_strong_code_roots() {
4772   RebuildStrongCodeRootClosure blob_cl(this);
4773   CodeCache::blobs_do(&blob_cl);
4774 }
4775 
4776 void G1CollectedHeap::initialize_serviceability() {
4777   _g1mm->initialize_serviceability();
4778 }
4779 
4780 MemoryUsage G1CollectedHeap::memory_usage() {
4781   return _g1mm->memory_usage();
4782 }
4783 
4784 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4785   return _g1mm->memory_managers();
4786 }
4787 
4788 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4789   return _g1mm->memory_pools();
4790 }
--- EOF ---