rev 57716 : [mq]: remove_cbl_mon

   1 /*
   2  * Copyright (c) 2001, 2020, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoaderDataGraph.hpp"
  27 #include "classfile/metadataOnStackMark.hpp"
  28 #include "classfile/stringTable.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "gc/g1/g1Allocator.inline.hpp"
  32 #include "gc/g1/g1Arguments.hpp"
  33 #include "gc/g1/g1BarrierSet.hpp"
  34 #include "gc/g1/g1CardTableEntryClosure.hpp"
  35 #include "gc/g1/g1CollectedHeap.inline.hpp"
  36 #include "gc/g1/g1CollectionSet.hpp"
  37 #include "gc/g1/g1CollectorState.hpp"
  38 #include "gc/g1/g1ConcurrentRefine.hpp"
  39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
  40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
  41 #include "gc/g1/g1DirtyCardQueue.hpp"
  42 #include "gc/g1/g1EvacStats.inline.hpp"
  43 #include "gc/g1/g1FullCollector.hpp"
  44 #include "gc/g1/g1GCPhaseTimes.hpp"
  45 #include "gc/g1/g1HeapSizingPolicy.hpp"
  46 #include "gc/g1/g1HeapTransition.hpp"
  47 #include "gc/g1/g1HeapVerifier.hpp"
  48 #include "gc/g1/g1HotCardCache.hpp"
  49 #include "gc/g1/g1MemoryPool.hpp"
  50 #include "gc/g1/g1OopClosures.inline.hpp"
  51 #include "gc/g1/g1ParallelCleaning.hpp"
  52 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  53 #include "gc/g1/g1Policy.hpp"
  54 #include "gc/g1/g1RedirtyCardsQueue.hpp"
  55 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  56 #include "gc/g1/g1RemSet.hpp"
  57 #include "gc/g1/g1RootClosures.hpp"
  58 #include "gc/g1/g1RootProcessor.hpp"
  59 #include "gc/g1/g1SATBMarkQueueSet.hpp"
  60 #include "gc/g1/g1StringDedup.hpp"
  61 #include "gc/g1/g1ThreadLocalData.hpp"
  62 #include "gc/g1/g1Trace.hpp"
  63 #include "gc/g1/g1YCTypes.hpp"
  64 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  65 #include "gc/g1/g1VMOperations.hpp"
  66 #include "gc/g1/heapRegion.inline.hpp"
  67 #include "gc/g1/heapRegionRemSet.hpp"
  68 #include "gc/g1/heapRegionSet.inline.hpp"
  69 #include "gc/shared/gcBehaviours.hpp"
  70 #include "gc/shared/gcHeapSummary.hpp"
  71 #include "gc/shared/gcId.hpp"
  72 #include "gc/shared/gcLocker.hpp"
  73 #include "gc/shared/gcTimer.hpp"
  74 #include "gc/shared/gcTraceTime.inline.hpp"
  75 #include "gc/shared/generationSpec.hpp"
  76 #include "gc/shared/isGCActiveMark.hpp"
  77 #include "gc/shared/locationPrinter.inline.hpp"
  78 #include "gc/shared/oopStorageParState.hpp"
  79 #include "gc/shared/preservedMarks.inline.hpp"
  80 #include "gc/shared/suspendibleThreadSet.hpp"
  81 #include "gc/shared/referenceProcessor.inline.hpp"
  82 #include "gc/shared/taskqueue.inline.hpp"
  83 #include "gc/shared/weakProcessor.inline.hpp"
  84 #include "gc/shared/workerPolicy.hpp"
  85 #include "logging/log.hpp"
  86 #include "memory/allocation.hpp"
  87 #include "memory/iterator.hpp"
  88 #include "memory/resourceArea.hpp"
  89 #include "memory/universe.hpp"
  90 #include "oops/access.inline.hpp"
  91 #include "oops/compressedOops.inline.hpp"
  92 #include "oops/oop.inline.hpp"
  93 #include "runtime/atomic.hpp"
  94 #include "runtime/flags/flagSetting.hpp"
  95 #include "runtime/handles.inline.hpp"
  96 #include "runtime/init.hpp"
  97 #include "runtime/orderAccess.hpp"
  98 #include "runtime/threadSMR.hpp"
  99 #include "runtime/vmThread.hpp"
 100 #include "utilities/align.hpp"
 101 #include "utilities/bitMap.inline.hpp"
 102 #include "utilities/globalDefinitions.hpp"
 103 #include "utilities/stack.inline.hpp"
 104 
 105 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
 106 
 107 // INVARIANTS/NOTES
 108 //
 109 // All allocation activity covered by the G1CollectedHeap interface is
 110 // serialized by acquiring the HeapLock.  This happens in mem_allocate
 111 // and allocate_new_tlab, which are the "entry" points to the
 112 // allocation code from the rest of the JVM.  (Note that this does not
 113 // apply to TLAB allocation, which is not part of this interface: it
 114 // is done by clients of this interface.)
 115 
 116 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
 117  private:
 118   size_t _num_dirtied;
 119   G1CollectedHeap* _g1h;
 120   G1CardTable* _g1_ct;
 121 
 122   HeapRegion* region_for_card(CardValue* card_ptr) const {
 123     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
 124   }
 125 
 126   bool will_become_free(HeapRegion* hr) const {
 127     // A region will be freed by free_collection_set if the region is in the
 128     // collection set and has not had an evacuation failure.
 129     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 130   }
 131 
 132  public:
 133   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
 134     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
 135 
 136   void do_card_ptr(CardValue* card_ptr, uint worker_id) {
 137     HeapRegion* hr = region_for_card(card_ptr);
 138 
 139     // Should only dirty cards in regions that won't be freed.
 140     if (!will_become_free(hr)) {
 141       *card_ptr = G1CardTable::dirty_card_val();
 142       _num_dirtied++;
 143     }
 144   }
 145 
 146   size_t num_dirtied()   const { return _num_dirtied; }
 147 };
 148 
 149 
 150 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 151   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 152 }
 153 
 154 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 155   // The from card cache is not the memory that is actually committed. So we cannot
 156   // take advantage of the zero_filled parameter.
 157   reset_from_card_cache(start_idx, num_regions);
 158 }
 159 
 160 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
 161   Ticks start = Ticks::now();
 162   workers()->run_task(task, workers()->active_workers());
 163   return Ticks::now() - start;
 164 }
 165 
 166 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 167                                              MemRegion mr) {
 168   return new HeapRegion(hrs_index, bot(), mr);
 169 }
 170 
 171 // Private methods.
 172 
 173 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
 174                                         HeapRegionType type,
 175                                         bool do_expand,
 176                                         uint node_index) {
 177   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 178          "the only time we use this to allocate a humongous region is "
 179          "when we are allocating a single humongous region");
 180 
 181   HeapRegion* res = _hrm->allocate_free_region(type, node_index);
 182 
 183   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 184     // Currently, only attempts to allocate GC alloc regions set
 185     // do_expand to true. So, we should only reach here during a
 186     // safepoint. If this assumption changes we might have to
 187     // reconsider the use of _expand_heap_after_alloc_failure.
 188     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 189 
 190     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 191                               word_size * HeapWordSize);
 192 
 193     assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
 194            "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
 195            word_size * HeapWordSize);
 196     if (expand_single_region(node_index)) {
 197       // Given that expand_single_region() succeeded in expanding the heap, and we
 198       // always expand the heap by an amount aligned to the heap
 199       // region size, the free list should in theory not be empty.
 200       // In either case allocate_free_region() will check for NULL.
 201       res = _hrm->allocate_free_region(type, node_index);
 202     } else {
 203       _expand_heap_after_alloc_failure = false;
 204     }
 205   }
 206   return res;
 207 }
 208 
 209 HeapWord*
 210 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 211                                                            uint num_regions,
 212                                                            size_t word_size) {
 213   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 214   assert(is_humongous(word_size), "word_size should be humongous");
 215   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 216 
 217   // Index of last region in the series.
 218   uint last = first + num_regions - 1;
 219 
 220   // We need to initialize the region(s) we just discovered. This is
 221   // a bit tricky given that it can happen concurrently with
 222   // refinement threads refining cards on these regions and
 223   // potentially wanting to refine the BOT as they are scanning
 224   // those cards (this can happen shortly after a cleanup; see CR
 225   // 6991377). So we have to set up the region(s) carefully and in
 226   // a specific order.
 227 
 228   // The word size sum of all the regions we will allocate.
 229   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 230   assert(word_size <= word_size_sum, "sanity");
 231 
 232   // This will be the "starts humongous" region.
 233   HeapRegion* first_hr = region_at(first);
 234   // The header of the new object will be placed at the bottom of
 235   // the first region.
 236   HeapWord* new_obj = first_hr->bottom();
 237   // This will be the new top of the new object.
 238   HeapWord* obj_top = new_obj + word_size;
 239 
 240   // First, we need to zero the header of the space that we will be
 241   // allocating. When we update top further down, some refinement
 242   // threads might try to scan the region. By zeroing the header we
 243   // ensure that any thread that will try to scan the region will
 244   // come across the zero klass word and bail out.
 245   //
 246   // NOTE: It would not have been correct to have used
 247   // CollectedHeap::fill_with_object() and make the space look like
 248   // an int array. The thread that is doing the allocation will
 249   // later update the object header to a potentially different array
 250   // type and, for a very short period of time, the klass and length
 251   // fields will be inconsistent. This could cause a refinement
 252   // thread to calculate the object size incorrectly.
 253   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 254 
 255   // Next, pad out the unused tail of the last region with filler
 256   // objects, for improved usage accounting.
 257   // How many words we use for filler objects.
 258   size_t word_fill_size = word_size_sum - word_size;
 259 
 260   // How many words memory we "waste" which cannot hold a filler object.
 261   size_t words_not_fillable = 0;
 262 
 263   if (word_fill_size >= min_fill_size()) {
 264     fill_with_objects(obj_top, word_fill_size);
 265   } else if (word_fill_size > 0) {
 266     // We have space to fill, but we cannot fit an object there.
 267     words_not_fillable = word_fill_size;
 268     word_fill_size = 0;
 269   }
 270 
 271   // We will set up the first region as "starts humongous". This
 272   // will also update the BOT covering all the regions to reflect
 273   // that there is a single object that starts at the bottom of the
 274   // first region.
 275   first_hr->set_starts_humongous(obj_top, word_fill_size);
 276   _policy->remset_tracker()->update_at_allocate(first_hr);
 277   // Then, if there are any, we will set up the "continues
 278   // humongous" regions.
 279   HeapRegion* hr = NULL;
 280   for (uint i = first + 1; i <= last; ++i) {
 281     hr = region_at(i);
 282     hr->set_continues_humongous(first_hr);
 283     _policy->remset_tracker()->update_at_allocate(hr);
 284   }
 285 
 286   // Up to this point no concurrent thread would have been able to
 287   // do any scanning on any region in this series. All the top
 288   // fields still point to bottom, so the intersection between
 289   // [bottom,top] and [card_start,card_end] will be empty. Before we
 290   // update the top fields, we'll do a storestore to make sure that
 291   // no thread sees the update to top before the zeroing of the
 292   // object header and the BOT initialization.
 293   OrderAccess::storestore();
 294 
 295   // Now, we will update the top fields of the "continues humongous"
 296   // regions except the last one.
 297   for (uint i = first; i < last; ++i) {
 298     hr = region_at(i);
 299     hr->set_top(hr->end());
 300   }
 301 
 302   hr = region_at(last);
 303   // If we cannot fit a filler object, we must set top to the end
 304   // of the humongous object, otherwise we cannot iterate the heap
 305   // and the BOT will not be complete.
 306   hr->set_top(hr->end() - words_not_fillable);
 307 
 308   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 309          "obj_top should be in last region");
 310 
 311   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 312 
 313   assert(words_not_fillable == 0 ||
 314          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 315          "Miscalculation in humongous allocation");
 316 
 317   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 318 
 319   for (uint i = first; i <= last; ++i) {
 320     hr = region_at(i);
 321     _humongous_set.add(hr);
 322     _hr_printer.alloc(hr);
 323   }
 324 
 325   return new_obj;
 326 }
 327 
 328 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 329   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 330   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 331 }
 332 
 333 // If could fit into free regions w/o expansion, try.
 334 // Otherwise, if can expand, do so.
 335 // Otherwise, if using ex regions might help, try with ex given back.
 336 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 337   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 338 
 339   _verifier->verify_region_sets_optional();
 340 
 341   uint first = G1_NO_HRM_INDEX;
 342   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 343 
 344   if (obj_regions == 1) {
 345     // Only one region to allocate, try to use a fast path by directly allocating
 346     // from the free lists. Do not try to expand here, we will potentially do that
 347     // later.
 348     HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
 349     if (hr != NULL) {
 350       first = hr->hrm_index();
 351     }
 352   } else {
 353     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 354     // are lucky enough to find some.
 355     first = _hrm->find_contiguous_only_empty(obj_regions);
 356     if (first != G1_NO_HRM_INDEX) {
 357       _hrm->allocate_free_regions_starting_at(first, obj_regions);
 358     }
 359   }
 360 
 361   if (first == G1_NO_HRM_INDEX) {
 362     // Policy: We could not find enough regions for the humongous object in the
 363     // free list. Look through the heap to find a mix of free and uncommitted regions.
 364     // If so, try expansion.
 365     first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
 366     if (first != G1_NO_HRM_INDEX) {
 367       // We found something. Make sure these regions are committed, i.e. expand
 368       // the heap. Alternatively we could do a defragmentation GC.
 369       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 370                                     word_size * HeapWordSize);
 371 
 372       _hrm->expand_at(first, obj_regions, workers());
 373       policy()->record_new_heap_size(num_regions());
 374 
 375 #ifdef ASSERT
 376       for (uint i = first; i < first + obj_regions; ++i) {
 377         HeapRegion* hr = region_at(i);
 378         assert(hr->is_free(), "sanity");
 379         assert(hr->is_empty(), "sanity");
 380         assert(is_on_master_free_list(hr), "sanity");
 381       }
 382 #endif
 383       _hrm->allocate_free_regions_starting_at(first, obj_regions);
 384     } else {
 385       // Policy: Potentially trigger a defragmentation GC.
 386     }
 387   }
 388 
 389   HeapWord* result = NULL;
 390   if (first != G1_NO_HRM_INDEX) {
 391     result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
 392     assert(result != NULL, "it should always return a valid result");
 393 
 394     // A successful humongous object allocation changes the used space
 395     // information of the old generation so we need to recalculate the
 396     // sizes and update the jstat counters here.
 397     g1mm()->update_sizes();
 398   }
 399 
 400   _verifier->verify_region_sets_optional();
 401 
 402   return result;
 403 }
 404 
 405 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
 406                                              size_t requested_size,
 407                                              size_t* actual_size) {
 408   assert_heap_not_locked_and_not_at_safepoint();
 409   assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
 410 
 411   return attempt_allocation(min_size, requested_size, actual_size);
 412 }
 413 
 414 HeapWord*
 415 G1CollectedHeap::mem_allocate(size_t word_size,
 416                               bool*  gc_overhead_limit_was_exceeded) {
 417   assert_heap_not_locked_and_not_at_safepoint();
 418 
 419   if (is_humongous(word_size)) {
 420     return attempt_allocation_humongous(word_size);
 421   }
 422   size_t dummy = 0;
 423   return attempt_allocation(word_size, word_size, &dummy);
 424 }
 425 
 426 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 427   ResourceMark rm; // For retrieving the thread names in log messages.
 428 
 429   // Make sure you read the note in attempt_allocation_humongous().
 430 
 431   assert_heap_not_locked_and_not_at_safepoint();
 432   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 433          "be called for humongous allocation requests");
 434 
 435   // We should only get here after the first-level allocation attempt
 436   // (attempt_allocation()) failed to allocate.
 437 
 438   // We will loop until a) we manage to successfully perform the
 439   // allocation or b) we successfully schedule a collection which
 440   // fails to perform the allocation. b) is the only case when we'll
 441   // return NULL.
 442   HeapWord* result = NULL;
 443   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 444     bool should_try_gc;
 445     uint gc_count_before;
 446 
 447     {
 448       MutexLocker x(Heap_lock);
 449       result = _allocator->attempt_allocation_locked(word_size);
 450       if (result != NULL) {
 451         return result;
 452       }
 453 
 454       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 455       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 456       // waiting because the GCLocker is active to not wait too long.
 457       if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
 458         // No need for an ergo message here, can_expand_young_list() does this when
 459         // it returns true.
 460         result = _allocator->attempt_allocation_force(word_size);
 461         if (result != NULL) {
 462           return result;
 463         }
 464       }
 465       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 466       // the GCLocker initiated GC has been performed and then retry. This includes
 467       // the case when the GC Locker is not active but has not been performed.
 468       should_try_gc = !GCLocker::needs_gc();
 469       // Read the GC count while still holding the Heap_lock.
 470       gc_count_before = total_collections();
 471     }
 472 
 473     if (should_try_gc) {
 474       bool succeeded;
 475       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 476                                    GCCause::_g1_inc_collection_pause);
 477       if (result != NULL) {
 478         assert(succeeded, "only way to get back a non-NULL result");
 479         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 480                              Thread::current()->name(), p2i(result));
 481         return result;
 482       }
 483 
 484       if (succeeded) {
 485         // We successfully scheduled a collection which failed to allocate. No
 486         // point in trying to allocate further. We'll just return NULL.
 487         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 488                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 489         return NULL;
 490       }
 491       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 492                            Thread::current()->name(), word_size);
 493     } else {
 494       // Failed to schedule a collection.
 495       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 496         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 497                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 498         return NULL;
 499       }
 500       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 501       // The GCLocker is either active or the GCLocker initiated
 502       // GC has not yet been performed. Stall until it is and
 503       // then retry the allocation.
 504       GCLocker::stall_until_clear();
 505       gclocker_retry_count += 1;
 506     }
 507 
 508     // We can reach here if we were unsuccessful in scheduling a
 509     // collection (because another thread beat us to it) or if we were
 510     // stalled due to the GC locker. In either can we should retry the
 511     // allocation attempt in case another thread successfully
 512     // performed a collection and reclaimed enough space. We do the
 513     // first attempt (without holding the Heap_lock) here and the
 514     // follow-on attempt will be at the start of the next loop
 515     // iteration (after taking the Heap_lock).
 516     size_t dummy = 0;
 517     result = _allocator->attempt_allocation(word_size, word_size, &dummy);
 518     if (result != NULL) {
 519       return result;
 520     }
 521 
 522     // Give a warning if we seem to be looping forever.
 523     if ((QueuedAllocationWarningCount > 0) &&
 524         (try_count % QueuedAllocationWarningCount == 0)) {
 525       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 526                              Thread::current()->name(), try_count, word_size);
 527     }
 528   }
 529 
 530   ShouldNotReachHere();
 531   return NULL;
 532 }
 533 
 534 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 535   assert_at_safepoint_on_vm_thread();
 536   if (_archive_allocator == NULL) {
 537     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 538   }
 539 }
 540 
 541 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 542   // Allocations in archive regions cannot be of a size that would be considered
 543   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 544   // may be different at archive-restore time.
 545   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 546 }
 547 
 548 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 549   assert_at_safepoint_on_vm_thread();
 550   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 551   if (is_archive_alloc_too_large(word_size)) {
 552     return NULL;
 553   }
 554   return _archive_allocator->archive_mem_allocate(word_size);
 555 }
 556 
 557 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 558                                               size_t end_alignment_in_bytes) {
 559   assert_at_safepoint_on_vm_thread();
 560   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 561 
 562   // Call complete_archive to do the real work, filling in the MemRegion
 563   // array with the archive regions.
 564   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 565   delete _archive_allocator;
 566   _archive_allocator = NULL;
 567 }
 568 
 569 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 570   assert(ranges != NULL, "MemRegion array NULL");
 571   assert(count != 0, "No MemRegions provided");
 572   MemRegion reserved = _hrm->reserved();
 573   for (size_t i = 0; i < count; i++) {
 574     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 575       return false;
 576     }
 577   }
 578   return true;
 579 }
 580 
 581 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 582                                             size_t count,
 583                                             bool open) {
 584   assert(!is_init_completed(), "Expect to be called at JVM init time");
 585   assert(ranges != NULL, "MemRegion array NULL");
 586   assert(count != 0, "No MemRegions provided");
 587   MutexLocker x(Heap_lock);
 588 
 589   MemRegion reserved = _hrm->reserved();
 590   HeapWord* prev_last_addr = NULL;
 591   HeapRegion* prev_last_region = NULL;
 592 
 593   // Temporarily disable pretouching of heap pages. This interface is used
 594   // when mmap'ing archived heap data in, so pre-touching is wasted.
 595   FlagSetting fs(AlwaysPreTouch, false);
 596 
 597   // Enable archive object checking used by G1MarkSweep. We have to let it know
 598   // about each archive range, so that objects in those ranges aren't marked.
 599   G1ArchiveAllocator::enable_archive_object_check();
 600 
 601   // For each specified MemRegion range, allocate the corresponding G1
 602   // regions and mark them as archive regions. We expect the ranges
 603   // in ascending starting address order, without overlap.
 604   for (size_t i = 0; i < count; i++) {
 605     MemRegion curr_range = ranges[i];
 606     HeapWord* start_address = curr_range.start();
 607     size_t word_size = curr_range.word_size();
 608     HeapWord* last_address = curr_range.last();
 609     size_t commits = 0;
 610 
 611     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 612               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 613               p2i(start_address), p2i(last_address));
 614     guarantee(start_address > prev_last_addr,
 615               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 616               p2i(start_address), p2i(prev_last_addr));
 617     prev_last_addr = last_address;
 618 
 619     // Check for ranges that start in the same G1 region in which the previous
 620     // range ended, and adjust the start address so we don't try to allocate
 621     // the same region again. If the current range is entirely within that
 622     // region, skip it, just adjusting the recorded top.
 623     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 624     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 625       start_address = start_region->end();
 626       if (start_address > last_address) {
 627         increase_used(word_size * HeapWordSize);
 628         start_region->set_top(last_address + 1);
 629         continue;
 630       }
 631       start_region->set_top(start_address);
 632       curr_range = MemRegion(start_address, last_address + 1);
 633       start_region = _hrm->addr_to_region(start_address);
 634     }
 635 
 636     // Perform the actual region allocation, exiting if it fails.
 637     // Then note how much new space we have allocated.
 638     if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
 639       return false;
 640     }
 641     increase_used(word_size * HeapWordSize);
 642     if (commits != 0) {
 643       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 644                                 HeapRegion::GrainWords * HeapWordSize * commits);
 645 
 646     }
 647 
 648     // Mark each G1 region touched by the range as archive, add it to
 649     // the old set, and set top.
 650     HeapRegion* curr_region = _hrm->addr_to_region(start_address);
 651     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 652     prev_last_region = last_region;
 653 
 654     while (curr_region != NULL) {
 655       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 656              "Region already in use (index %u)", curr_region->hrm_index());
 657       if (open) {
 658         curr_region->set_open_archive();
 659       } else {
 660         curr_region->set_closed_archive();
 661       }
 662       _hr_printer.alloc(curr_region);
 663       _archive_set.add(curr_region);
 664       HeapWord* top;
 665       HeapRegion* next_region;
 666       if (curr_region != last_region) {
 667         top = curr_region->end();
 668         next_region = _hrm->next_region_in_heap(curr_region);
 669       } else {
 670         top = last_address + 1;
 671         next_region = NULL;
 672       }
 673       curr_region->set_top(top);
 674       curr_region = next_region;
 675     }
 676 
 677     // Notify mark-sweep of the archive
 678     G1ArchiveAllocator::set_range_archive(curr_range, open);
 679   }
 680   return true;
 681 }
 682 
 683 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 684   assert(!is_init_completed(), "Expect to be called at JVM init time");
 685   assert(ranges != NULL, "MemRegion array NULL");
 686   assert(count != 0, "No MemRegions provided");
 687   MemRegion reserved = _hrm->reserved();
 688   HeapWord *prev_last_addr = NULL;
 689   HeapRegion* prev_last_region = NULL;
 690 
 691   // For each MemRegion, create filler objects, if needed, in the G1 regions
 692   // that contain the address range. The address range actually within the
 693   // MemRegion will not be modified. That is assumed to have been initialized
 694   // elsewhere, probably via an mmap of archived heap data.
 695   MutexLocker x(Heap_lock);
 696   for (size_t i = 0; i < count; i++) {
 697     HeapWord* start_address = ranges[i].start();
 698     HeapWord* last_address = ranges[i].last();
 699 
 700     assert(reserved.contains(start_address) && reserved.contains(last_address),
 701            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 702            p2i(start_address), p2i(last_address));
 703     assert(start_address > prev_last_addr,
 704            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 705            p2i(start_address), p2i(prev_last_addr));
 706 
 707     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 708     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 709     HeapWord* bottom_address = start_region->bottom();
 710 
 711     // Check for a range beginning in the same region in which the
 712     // previous one ended.
 713     if (start_region == prev_last_region) {
 714       bottom_address = prev_last_addr + 1;
 715     }
 716 
 717     // Verify that the regions were all marked as archive regions by
 718     // alloc_archive_regions.
 719     HeapRegion* curr_region = start_region;
 720     while (curr_region != NULL) {
 721       guarantee(curr_region->is_archive(),
 722                 "Expected archive region at index %u", curr_region->hrm_index());
 723       if (curr_region != last_region) {
 724         curr_region = _hrm->next_region_in_heap(curr_region);
 725       } else {
 726         curr_region = NULL;
 727       }
 728     }
 729 
 730     prev_last_addr = last_address;
 731     prev_last_region = last_region;
 732 
 733     // Fill the memory below the allocated range with dummy object(s),
 734     // if the region bottom does not match the range start, or if the previous
 735     // range ended within the same G1 region, and there is a gap.
 736     if (start_address != bottom_address) {
 737       size_t fill_size = pointer_delta(start_address, bottom_address);
 738       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 739       increase_used(fill_size * HeapWordSize);
 740     }
 741   }
 742 }
 743 
 744 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
 745                                                      size_t desired_word_size,
 746                                                      size_t* actual_word_size) {
 747   assert_heap_not_locked_and_not_at_safepoint();
 748   assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
 749          "be called for humongous allocation requests");
 750 
 751   HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
 752 
 753   if (result == NULL) {
 754     *actual_word_size = desired_word_size;
 755     result = attempt_allocation_slow(desired_word_size);
 756   }
 757 
 758   assert_heap_not_locked();
 759   if (result != NULL) {
 760     assert(*actual_word_size != 0, "Actual size must have been set here");
 761     dirty_young_block(result, *actual_word_size);
 762   } else {
 763     *actual_word_size = 0;
 764   }
 765 
 766   return result;
 767 }
 768 
 769 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 770   assert(!is_init_completed(), "Expect to be called at JVM init time");
 771   assert(ranges != NULL, "MemRegion array NULL");
 772   assert(count != 0, "No MemRegions provided");
 773   MemRegion reserved = _hrm->reserved();
 774   HeapWord* prev_last_addr = NULL;
 775   HeapRegion* prev_last_region = NULL;
 776   size_t size_used = 0;
 777   size_t uncommitted_regions = 0;
 778 
 779   // For each Memregion, free the G1 regions that constitute it, and
 780   // notify mark-sweep that the range is no longer to be considered 'archive.'
 781   MutexLocker x(Heap_lock);
 782   for (size_t i = 0; i < count; i++) {
 783     HeapWord* start_address = ranges[i].start();
 784     HeapWord* last_address = ranges[i].last();
 785 
 786     assert(reserved.contains(start_address) && reserved.contains(last_address),
 787            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 788            p2i(start_address), p2i(last_address));
 789     assert(start_address > prev_last_addr,
 790            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 791            p2i(start_address), p2i(prev_last_addr));
 792     size_used += ranges[i].byte_size();
 793     prev_last_addr = last_address;
 794 
 795     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 796     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 797 
 798     // Check for ranges that start in the same G1 region in which the previous
 799     // range ended, and adjust the start address so we don't try to free
 800     // the same region again. If the current range is entirely within that
 801     // region, skip it.
 802     if (start_region == prev_last_region) {
 803       start_address = start_region->end();
 804       if (start_address > last_address) {
 805         continue;
 806       }
 807       start_region = _hrm->addr_to_region(start_address);
 808     }
 809     prev_last_region = last_region;
 810 
 811     // After verifying that each region was marked as an archive region by
 812     // alloc_archive_regions, set it free and empty and uncommit it.
 813     HeapRegion* curr_region = start_region;
 814     while (curr_region != NULL) {
 815       guarantee(curr_region->is_archive(),
 816                 "Expected archive region at index %u", curr_region->hrm_index());
 817       uint curr_index = curr_region->hrm_index();
 818       _archive_set.remove(curr_region);
 819       curr_region->set_free();
 820       curr_region->set_top(curr_region->bottom());
 821       if (curr_region != last_region) {
 822         curr_region = _hrm->next_region_in_heap(curr_region);
 823       } else {
 824         curr_region = NULL;
 825       }
 826       _hrm->shrink_at(curr_index, 1);
 827       uncommitted_regions++;
 828     }
 829 
 830     // Notify mark-sweep that this is no longer an archive range.
 831     G1ArchiveAllocator::clear_range_archive(ranges[i]);
 832   }
 833 
 834   if (uncommitted_regions != 0) {
 835     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 836                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 837   }
 838   decrease_used(size_used);
 839 }
 840 
 841 oop G1CollectedHeap::materialize_archived_object(oop obj) {
 842   assert(obj != NULL, "archived obj is NULL");
 843   assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
 844 
 845   // Loading an archived object makes it strongly reachable. If it is
 846   // loaded during concurrent marking, it must be enqueued to the SATB
 847   // queue, shading the previously white object gray.
 848   G1BarrierSet::enqueue(obj);
 849 
 850   return obj;
 851 }
 852 
 853 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 854   ResourceMark rm; // For retrieving the thread names in log messages.
 855 
 856   // The structure of this method has a lot of similarities to
 857   // attempt_allocation_slow(). The reason these two were not merged
 858   // into a single one is that such a method would require several "if
 859   // allocation is not humongous do this, otherwise do that"
 860   // conditional paths which would obscure its flow. In fact, an early
 861   // version of this code did use a unified method which was harder to
 862   // follow and, as a result, it had subtle bugs that were hard to
 863   // track down. So keeping these two methods separate allows each to
 864   // be more readable. It will be good to keep these two in sync as
 865   // much as possible.
 866 
 867   assert_heap_not_locked_and_not_at_safepoint();
 868   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 869          "should only be called for humongous allocations");
 870 
 871   // Humongous objects can exhaust the heap quickly, so we should check if we
 872   // need to start a marking cycle at each humongous object allocation. We do
 873   // the check before we do the actual allocation. The reason for doing it
 874   // before the allocation is that we avoid having to keep track of the newly
 875   // allocated memory while we do a GC.
 876   if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
 877                                            word_size)) {
 878     collect(GCCause::_g1_humongous_allocation);
 879   }
 880 
 881   // We will loop until a) we manage to successfully perform the
 882   // allocation or b) we successfully schedule a collection which
 883   // fails to perform the allocation. b) is the only case when we'll
 884   // return NULL.
 885   HeapWord* result = NULL;
 886   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 887     bool should_try_gc;
 888     uint gc_count_before;
 889 
 890 
 891     {
 892       MutexLocker x(Heap_lock);
 893 
 894       // Given that humongous objects are not allocated in young
 895       // regions, we'll first try to do the allocation without doing a
 896       // collection hoping that there's enough space in the heap.
 897       result = humongous_obj_allocate(word_size);
 898       if (result != NULL) {
 899         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 900         policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 901         return result;
 902       }
 903 
 904       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 905       // the GCLocker initiated GC has been performed and then retry. This includes
 906       // the case when the GC Locker is not active but has not been performed.
 907       should_try_gc = !GCLocker::needs_gc();
 908       // Read the GC count while still holding the Heap_lock.
 909       gc_count_before = total_collections();
 910     }
 911 
 912     if (should_try_gc) {
 913       bool succeeded;
 914       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 915                                    GCCause::_g1_humongous_allocation);
 916       if (result != NULL) {
 917         assert(succeeded, "only way to get back a non-NULL result");
 918         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 919                              Thread::current()->name(), p2i(result));
 920         return result;
 921       }
 922 
 923       if (succeeded) {
 924         // We successfully scheduled a collection which failed to allocate. No
 925         // point in trying to allocate further. We'll just return NULL.
 926         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 927                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 928         return NULL;
 929       }
 930       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 931                            Thread::current()->name(), word_size);
 932     } else {
 933       // Failed to schedule a collection.
 934       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 935         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 936                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 937         return NULL;
 938       }
 939       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 940       // The GCLocker is either active or the GCLocker initiated
 941       // GC has not yet been performed. Stall until it is and
 942       // then retry the allocation.
 943       GCLocker::stall_until_clear();
 944       gclocker_retry_count += 1;
 945     }
 946 
 947 
 948     // We can reach here if we were unsuccessful in scheduling a
 949     // collection (because another thread beat us to it) or if we were
 950     // stalled due to the GC locker. In either can we should retry the
 951     // allocation attempt in case another thread successfully
 952     // performed a collection and reclaimed enough space.
 953     // Humongous object allocation always needs a lock, so we wait for the retry
 954     // in the next iteration of the loop, unlike for the regular iteration case.
 955     // Give a warning if we seem to be looping forever.
 956 
 957     if ((QueuedAllocationWarningCount > 0) &&
 958         (try_count % QueuedAllocationWarningCount == 0)) {
 959       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 960                              Thread::current()->name(), try_count, word_size);
 961     }
 962   }
 963 
 964   ShouldNotReachHere();
 965   return NULL;
 966 }
 967 
 968 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 969                                                            bool expect_null_mutator_alloc_region) {
 970   assert_at_safepoint_on_vm_thread();
 971   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 972          "the current alloc region was unexpectedly found to be non-NULL");
 973 
 974   if (!is_humongous(word_size)) {
 975     return _allocator->attempt_allocation_locked(word_size);
 976   } else {
 977     HeapWord* result = humongous_obj_allocate(word_size);
 978     if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
 979       collector_state()->set_initiate_conc_mark_if_possible(true);
 980     }
 981     return result;
 982   }
 983 
 984   ShouldNotReachHere();
 985 }
 986 
 987 class PostCompactionPrinterClosure: public HeapRegionClosure {
 988 private:
 989   G1HRPrinter* _hr_printer;
 990 public:
 991   bool do_heap_region(HeapRegion* hr) {
 992     assert(!hr->is_young(), "not expecting to find young regions");
 993     _hr_printer->post_compaction(hr);
 994     return false;
 995   }
 996 
 997   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 998     : _hr_printer(hr_printer) { }
 999 };
1000 
1001 void G1CollectedHeap::print_hrm_post_compaction() {
1002   if (_hr_printer.is_active()) {
1003     PostCompactionPrinterClosure cl(hr_printer());
1004     heap_region_iterate(&cl);
1005   }
1006 }
1007 
1008 void G1CollectedHeap::abort_concurrent_cycle() {
1009   // If we start the compaction before the CM threads finish
1010   // scanning the root regions we might trip them over as we'll
1011   // be moving objects / updating references. So let's wait until
1012   // they are done. By telling them to abort, they should complete
1013   // early.
1014   _cm->root_regions()->abort();
1015   _cm->root_regions()->wait_until_scan_finished();
1016 
1017   // Disable discovery and empty the discovered lists
1018   // for the CM ref processor.
1019   _ref_processor_cm->disable_discovery();
1020   _ref_processor_cm->abandon_partial_discovery();
1021   _ref_processor_cm->verify_no_references_recorded();
1022 
1023   // Abandon current iterations of concurrent marking and concurrent
1024   // refinement, if any are in progress.
1025   concurrent_mark()->concurrent_cycle_abort();
1026 }
1027 
1028 void G1CollectedHeap::prepare_heap_for_full_collection() {
1029   // Make sure we'll choose a new allocation region afterwards.
1030   _allocator->release_mutator_alloc_regions();
1031   _allocator->abandon_gc_alloc_regions();
1032 
1033   // We may have added regions to the current incremental collection
1034   // set between the last GC or pause and now. We need to clear the
1035   // incremental collection set and then start rebuilding it afresh
1036   // after this full GC.
1037   abandon_collection_set(collection_set());
1038 
1039   tear_down_region_sets(false /* free_list_only */);
1040 
1041   hrm()->prepare_for_full_collection_start();
1042 }
1043 
1044 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1045   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1046   assert_used_and_recalculate_used_equal(this);
1047   _verifier->verify_region_sets_optional();
1048   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1049   _verifier->check_bitmaps("Full GC Start");
1050 }
1051 
1052 void G1CollectedHeap::prepare_heap_for_mutators() {
1053   hrm()->prepare_for_full_collection_end();
1054 
1055   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1056   ClassLoaderDataGraph::purge();
1057   MetaspaceUtils::verify_metrics();
1058 
1059   // Prepare heap for normal collections.
1060   assert(num_free_regions() == 0, "we should not have added any free regions");
1061   rebuild_region_sets(false /* free_list_only */);
1062   abort_refinement();
1063   resize_heap_if_necessary();
1064 
1065   // Rebuild the strong code root lists for each region
1066   rebuild_strong_code_roots();
1067 
1068   // Purge code root memory
1069   purge_code_root_memory();
1070 
1071   // Start a new incremental collection set for the next pause
1072   start_new_collection_set();
1073 
1074   _allocator->init_mutator_alloc_regions();
1075 
1076   // Post collection state updates.
1077   MetaspaceGC::compute_new_size();
1078 }
1079 
1080 void G1CollectedHeap::abort_refinement() {
1081   if (_hot_card_cache->use_cache()) {
1082     _hot_card_cache->reset_hot_cache();
1083   }
1084 
1085   // Discard all remembered set updates.
1086   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1087   assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1088          "DCQS should be empty");
1089 }
1090 
1091 void G1CollectedHeap::verify_after_full_collection() {
1092   _hrm->verify_optional();
1093   _verifier->verify_region_sets_optional();
1094   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1095   // Clear the previous marking bitmap, if needed for bitmap verification.
1096   // Note we cannot do this when we clear the next marking bitmap in
1097   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1098   // objects marked during a full GC against the previous bitmap.
1099   // But we need to clear it before calling check_bitmaps below since
1100   // the full GC has compacted objects and updated TAMS but not updated
1101   // the prev bitmap.
1102   if (G1VerifyBitmaps) {
1103     GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1104     _cm->clear_prev_bitmap(workers());
1105   }
1106   // This call implicitly verifies that the next bitmap is clear after Full GC.
1107   _verifier->check_bitmaps("Full GC End");
1108 
1109   // At this point there should be no regions in the
1110   // entire heap tagged as young.
1111   assert(check_young_list_empty(), "young list should be empty at this point");
1112 
1113   // Note: since we've just done a full GC, concurrent
1114   // marking is no longer active. Therefore we need not
1115   // re-enable reference discovery for the CM ref processor.
1116   // That will be done at the start of the next marking cycle.
1117   // We also know that the STW processor should no longer
1118   // discover any new references.
1119   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1120   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1121   _ref_processor_stw->verify_no_references_recorded();
1122   _ref_processor_cm->verify_no_references_recorded();
1123 }
1124 
1125 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1126   // Post collection logging.
1127   // We should do this after we potentially resize the heap so
1128   // that all the COMMIT / UNCOMMIT events are generated before
1129   // the compaction events.
1130   print_hrm_post_compaction();
1131   heap_transition->print();
1132   print_heap_after_gc();
1133   print_heap_regions();
1134 #ifdef TRACESPINNING
1135   ParallelTaskTerminator::print_termination_counts();
1136 #endif
1137 }
1138 
1139 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1140                                          bool clear_all_soft_refs) {
1141   assert_at_safepoint_on_vm_thread();
1142 
1143   if (GCLocker::check_active_before_gc()) {
1144     // Full GC was not completed.
1145     return false;
1146   }
1147 
1148   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1149       soft_ref_policy()->should_clear_all_soft_refs();
1150 
1151   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1152   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1153 
1154   collector.prepare_collection();
1155   collector.collect();
1156   collector.complete_collection();
1157 
1158   // Full collection was successfully completed.
1159   return true;
1160 }
1161 
1162 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1163   // Currently, there is no facility in the do_full_collection(bool) API to notify
1164   // the caller that the collection did not succeed (e.g., because it was locked
1165   // out by the GC locker). So, right now, we'll ignore the return value.
1166   bool dummy = do_full_collection(true,                /* explicit_gc */
1167                                   clear_all_soft_refs);
1168 }
1169 
1170 void G1CollectedHeap::resize_heap_if_necessary() {
1171   assert_at_safepoint_on_vm_thread();
1172 
1173   // Capacity, free and used after the GC counted as full regions to
1174   // include the waste in the following calculations.
1175   const size_t capacity_after_gc = capacity();
1176   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1177 
1178   // This is enforced in arguments.cpp.
1179   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1180          "otherwise the code below doesn't make sense");
1181 
1182   // We don't have floating point command-line arguments
1183   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1184   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1185   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1186   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1187 
1188   // We have to be careful here as these two calculations can overflow
1189   // 32-bit size_t's.
1190   double used_after_gc_d = (double) used_after_gc;
1191   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1192   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1193 
1194   // Let's make sure that they are both under the max heap size, which
1195   // by default will make them fit into a size_t.
1196   double desired_capacity_upper_bound = (double) MaxHeapSize;
1197   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1198                                     desired_capacity_upper_bound);
1199   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1200                                     desired_capacity_upper_bound);
1201 
1202   // We can now safely turn them into size_t's.
1203   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1204   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1205 
1206   // This assert only makes sense here, before we adjust them
1207   // with respect to the min and max heap size.
1208   assert(minimum_desired_capacity <= maximum_desired_capacity,
1209          "minimum_desired_capacity = " SIZE_FORMAT ", "
1210          "maximum_desired_capacity = " SIZE_FORMAT,
1211          minimum_desired_capacity, maximum_desired_capacity);
1212 
1213   // Should not be greater than the heap max size. No need to adjust
1214   // it with respect to the heap min size as it's a lower bound (i.e.,
1215   // we'll try to make the capacity larger than it, not smaller).
1216   minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1217   // Should not be less than the heap min size. No need to adjust it
1218   // with respect to the heap max size as it's an upper bound (i.e.,
1219   // we'll try to make the capacity smaller than it, not greater).
1220   maximum_desired_capacity =  MAX2(maximum_desired_capacity, MinHeapSize);
1221 
1222   if (capacity_after_gc < minimum_desired_capacity) {
1223     // Don't expand unless it's significant
1224     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1225 
1226     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1227                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1228                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1229                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1230 
1231     expand(expand_bytes, _workers);
1232 
1233     // No expansion, now see if we want to shrink
1234   } else if (capacity_after_gc > maximum_desired_capacity) {
1235     // Capacity too large, compute shrinking size
1236     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1237 
1238     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1239                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1240                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1241                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1242 
1243     shrink(shrink_bytes);
1244   }
1245 }
1246 
1247 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1248                                                             bool do_gc,
1249                                                             bool clear_all_soft_refs,
1250                                                             bool expect_null_mutator_alloc_region,
1251                                                             bool* gc_succeeded) {
1252   *gc_succeeded = true;
1253   // Let's attempt the allocation first.
1254   HeapWord* result =
1255     attempt_allocation_at_safepoint(word_size,
1256                                     expect_null_mutator_alloc_region);
1257   if (result != NULL) {
1258     return result;
1259   }
1260 
1261   // In a G1 heap, we're supposed to keep allocation from failing by
1262   // incremental pauses.  Therefore, at least for now, we'll favor
1263   // expansion over collection.  (This might change in the future if we can
1264   // do something smarter than full collection to satisfy a failed alloc.)
1265   result = expand_and_allocate(word_size);
1266   if (result != NULL) {
1267     return result;
1268   }
1269 
1270   if (do_gc) {
1271     // Expansion didn't work, we'll try to do a Full GC.
1272     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1273                                        clear_all_soft_refs);
1274   }
1275 
1276   return NULL;
1277 }
1278 
1279 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1280                                                      bool* succeeded) {
1281   assert_at_safepoint_on_vm_thread();
1282 
1283   // Attempts to allocate followed by Full GC.
1284   HeapWord* result =
1285     satisfy_failed_allocation_helper(word_size,
1286                                      true,  /* do_gc */
1287                                      false, /* clear_all_soft_refs */
1288                                      false, /* expect_null_mutator_alloc_region */
1289                                      succeeded);
1290 
1291   if (result != NULL || !*succeeded) {
1292     return result;
1293   }
1294 
1295   // Attempts to allocate followed by Full GC that will collect all soft references.
1296   result = satisfy_failed_allocation_helper(word_size,
1297                                             true, /* do_gc */
1298                                             true, /* clear_all_soft_refs */
1299                                             true, /* expect_null_mutator_alloc_region */
1300                                             succeeded);
1301 
1302   if (result != NULL || !*succeeded) {
1303     return result;
1304   }
1305 
1306   // Attempts to allocate, no GC
1307   result = satisfy_failed_allocation_helper(word_size,
1308                                             false, /* do_gc */
1309                                             false, /* clear_all_soft_refs */
1310                                             true,  /* expect_null_mutator_alloc_region */
1311                                             succeeded);
1312 
1313   if (result != NULL) {
1314     return result;
1315   }
1316 
1317   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1318          "Flag should have been handled and cleared prior to this point");
1319 
1320   // What else?  We might try synchronous finalization later.  If the total
1321   // space available is large enough for the allocation, then a more
1322   // complete compaction phase than we've tried so far might be
1323   // appropriate.
1324   return NULL;
1325 }
1326 
1327 // Attempting to expand the heap sufficiently
1328 // to support an allocation of the given "word_size".  If
1329 // successful, perform the allocation and return the address of the
1330 // allocated block, or else "NULL".
1331 
1332 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1333   assert_at_safepoint_on_vm_thread();
1334 
1335   _verifier->verify_region_sets_optional();
1336 
1337   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1338   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1339                             word_size * HeapWordSize);
1340 
1341 
1342   if (expand(expand_bytes, _workers)) {
1343     _hrm->verify_optional();
1344     _verifier->verify_region_sets_optional();
1345     return attempt_allocation_at_safepoint(word_size,
1346                                            false /* expect_null_mutator_alloc_region */);
1347   }
1348   return NULL;
1349 }
1350 
1351 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1352   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1353   aligned_expand_bytes = align_up(aligned_expand_bytes,
1354                                        HeapRegion::GrainBytes);
1355 
1356   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1357                             expand_bytes, aligned_expand_bytes);
1358 
1359   if (is_maximal_no_gc()) {
1360     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1361     return false;
1362   }
1363 
1364   double expand_heap_start_time_sec = os::elapsedTime();
1365   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1366   assert(regions_to_expand > 0, "Must expand by at least one region");
1367 
1368   uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1369   if (expand_time_ms != NULL) {
1370     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1371   }
1372 
1373   if (expanded_by > 0) {
1374     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1375     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1376     policy()->record_new_heap_size(num_regions());
1377   } else {
1378     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1379 
1380     // The expansion of the virtual storage space was unsuccessful.
1381     // Let's see if it was because we ran out of swap.
1382     if (G1ExitOnExpansionFailure &&
1383         _hrm->available() >= regions_to_expand) {
1384       // We had head room...
1385       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1386     }
1387   }
1388   return regions_to_expand > 0;
1389 }
1390 
1391 bool G1CollectedHeap::expand_single_region(uint node_index) {
1392   uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1393 
1394   if (expanded_by == 0) {
1395     assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1396     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1397     return false;
1398   }
1399 
1400   policy()->record_new_heap_size(num_regions());
1401   return true;
1402 }
1403 
1404 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1405   size_t aligned_shrink_bytes =
1406     ReservedSpace::page_align_size_down(shrink_bytes);
1407   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1408                                          HeapRegion::GrainBytes);
1409   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1410 
1411   uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1412   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1413 
1414   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",
1415                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1416   if (num_regions_removed > 0) {
1417     policy()->record_new_heap_size(num_regions());
1418   } else {
1419     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1420   }
1421 }
1422 
1423 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1424   _verifier->verify_region_sets_optional();
1425 
1426   // We should only reach here at the end of a Full GC or during Remark which
1427   // means we should not not be holding to any GC alloc regions. The method
1428   // below will make sure of that and do any remaining clean up.
1429   _allocator->abandon_gc_alloc_regions();
1430 
1431   // Instead of tearing down / rebuilding the free lists here, we
1432   // could instead use the remove_all_pending() method on free_list to
1433   // remove only the ones that we need to remove.
1434   tear_down_region_sets(true /* free_list_only */);
1435   shrink_helper(shrink_bytes);
1436   rebuild_region_sets(true /* free_list_only */);
1437 
1438   _hrm->verify_optional();
1439   _verifier->verify_region_sets_optional();
1440 }
1441 
1442 class OldRegionSetChecker : public HeapRegionSetChecker {
1443 public:
1444   void check_mt_safety() {
1445     // Master Old Set MT safety protocol:
1446     // (a) If we're at a safepoint, operations on the master old set
1447     // should be invoked:
1448     // - by the VM thread (which will serialize them), or
1449     // - by the GC workers while holding the FreeList_lock, if we're
1450     //   at a safepoint for an evacuation pause (this lock is taken
1451     //   anyway when an GC alloc region is retired so that a new one
1452     //   is allocated from the free list), or
1453     // - by the GC workers while holding the OldSets_lock, if we're at a
1454     //   safepoint for a cleanup pause.
1455     // (b) If we're not at a safepoint, operations on the master old set
1456     // should be invoked while holding the Heap_lock.
1457 
1458     if (SafepointSynchronize::is_at_safepoint()) {
1459       guarantee(Thread::current()->is_VM_thread() ||
1460                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1461                 "master old set MT safety protocol at a safepoint");
1462     } else {
1463       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1464     }
1465   }
1466   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1467   const char* get_description() { return "Old Regions"; }
1468 };
1469 
1470 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1471 public:
1472   void check_mt_safety() {
1473     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1474               "May only change archive regions during initialization or safepoint.");
1475   }
1476   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1477   const char* get_description() { return "Archive Regions"; }
1478 };
1479 
1480 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1481 public:
1482   void check_mt_safety() {
1483     // Humongous Set MT safety protocol:
1484     // (a) If we're at a safepoint, operations on the master humongous
1485     // set should be invoked by either the VM thread (which will
1486     // serialize them) or by the GC workers while holding the
1487     // OldSets_lock.
1488     // (b) If we're not at a safepoint, operations on the master
1489     // humongous set should be invoked while holding the Heap_lock.
1490 
1491     if (SafepointSynchronize::is_at_safepoint()) {
1492       guarantee(Thread::current()->is_VM_thread() ||
1493                 OldSets_lock->owned_by_self(),
1494                 "master humongous set MT safety protocol at a safepoint");
1495     } else {
1496       guarantee(Heap_lock->owned_by_self(),
1497                 "master humongous set MT safety protocol outside a safepoint");
1498     }
1499   }
1500   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1501   const char* get_description() { return "Humongous Regions"; }
1502 };
1503 
1504 G1CollectedHeap::G1CollectedHeap() :
1505   CollectedHeap(),
1506   _young_gen_sampling_thread(NULL),
1507   _workers(NULL),
1508   _card_table(NULL),
1509   _soft_ref_policy(),
1510   _old_set("Old Region Set", new OldRegionSetChecker()),
1511   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1512   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1513   _bot(NULL),
1514   _listener(),
1515   _numa(G1NUMA::create()),
1516   _hrm(NULL),
1517   _allocator(NULL),
1518   _verifier(NULL),
1519   _summary_bytes_used(0),
1520   _bytes_used_during_gc(0),
1521   _archive_allocator(NULL),
1522   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1523   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1524   _expand_heap_after_alloc_failure(true),
1525   _g1mm(NULL),
1526   _humongous_reclaim_candidates(),
1527   _has_humongous_reclaim_candidates(false),
1528   _hr_printer(),
1529   _collector_state(),
1530   _old_marking_cycles_started(0),
1531   _old_marking_cycles_completed(0),
1532   _eden(),
1533   _survivor(),
1534   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1535   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1536   _policy(G1Policy::create_policy(_gc_timer_stw)),
1537   _heap_sizing_policy(NULL),
1538   _collection_set(this, _policy),
1539   _hot_card_cache(NULL),
1540   _rem_set(NULL),
1541   _cm(NULL),
1542   _cm_thread(NULL),
1543   _cr(NULL),
1544   _task_queues(NULL),
1545   _evacuation_failed(false),
1546   _evacuation_failed_info_array(NULL),
1547   _preserved_marks_set(true /* in_c_heap */),
1548 #ifndef PRODUCT
1549   _evacuation_failure_alot_for_current_gc(false),
1550   _evacuation_failure_alot_gc_number(0),
1551   _evacuation_failure_alot_count(0),
1552 #endif
1553   _ref_processor_stw(NULL),
1554   _is_alive_closure_stw(this),
1555   _is_subject_to_discovery_stw(this),
1556   _ref_processor_cm(NULL),
1557   _is_alive_closure_cm(this),
1558   _is_subject_to_discovery_cm(this),
1559   _region_attr() {
1560 
1561   _verifier = new G1HeapVerifier(this);
1562 
1563   _allocator = new G1Allocator(this);
1564 
1565   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1566 
1567   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1568 
1569   // Override the default _filler_array_max_size so that no humongous filler
1570   // objects are created.
1571   _filler_array_max_size = _humongous_object_threshold_in_words;
1572 
1573   uint n_queues = ParallelGCThreads;
1574   _task_queues = new RefToScanQueueSet(n_queues);
1575 
1576   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1577 
1578   for (uint i = 0; i < n_queues; i++) {
1579     RefToScanQueue* q = new RefToScanQueue();
1580     q->initialize();
1581     _task_queues->register_queue(i, q);
1582     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1583   }
1584 
1585   // Initialize the G1EvacuationFailureALot counters and flags.
1586   NOT_PRODUCT(reset_evacuation_should_fail();)
1587   _gc_tracer_stw->initialize();
1588 
1589   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1590 }
1591 
1592 static size_t actual_reserved_page_size(ReservedSpace rs) {
1593   size_t page_size = os::vm_page_size();
1594   if (UseLargePages) {
1595     // There are two ways to manage large page memory.
1596     // 1. OS supports committing large page memory.
1597     // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1598     //    And ReservedSpace calls it 'special'. If we failed to set 'special',
1599     //    we reserved memory without large page.
1600     if (os::can_commit_large_page_memory() || rs.special()) {
1601       // An alignment at ReservedSpace comes from preferred page size or
1602       // heap alignment, and if the alignment came from heap alignment, it could be
1603       // larger than large pages size. So need to cap with the large page size.
1604       page_size = MIN2(rs.alignment(), os::large_page_size());
1605     }
1606   }
1607 
1608   return page_size;
1609 }
1610 
1611 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1612                                                                  size_t size,
1613                                                                  size_t translation_factor) {
1614   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1615   // Allocate a new reserved space, preferring to use large pages.
1616   ReservedSpace rs(size, preferred_page_size);
1617   size_t page_size = actual_reserved_page_size(rs);
1618   G1RegionToSpaceMapper* result  =
1619     G1RegionToSpaceMapper::create_mapper(rs,
1620                                          size,
1621                                          page_size,
1622                                          HeapRegion::GrainBytes,
1623                                          translation_factor,
1624                                          mtGC);
1625 
1626   os::trace_page_sizes_for_requested_size(description,
1627                                           size,
1628                                           preferred_page_size,
1629                                           page_size,
1630                                           rs.base(),
1631                                           rs.size());
1632 
1633   return result;
1634 }
1635 
1636 jint G1CollectedHeap::initialize_concurrent_refinement() {
1637   jint ecode = JNI_OK;
1638   _cr = G1ConcurrentRefine::create(&ecode);
1639   return ecode;
1640 }
1641 
1642 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1643   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1644   if (_young_gen_sampling_thread->osthread() == NULL) {
1645     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1646     return JNI_ENOMEM;
1647   }
1648   return JNI_OK;
1649 }
1650 
1651 jint G1CollectedHeap::initialize() {
1652 
1653   // Necessary to satisfy locking discipline assertions.
1654 
1655   MutexLocker x(Heap_lock);
1656 
1657   // While there are no constraints in the GC code that HeapWordSize
1658   // be any particular value, there are multiple other areas in the
1659   // system which believe this to be true (e.g. oop->object_size in some
1660   // cases incorrectly returns the size in wordSize units rather than
1661   // HeapWordSize).
1662   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1663 
1664   size_t init_byte_size = InitialHeapSize;
1665   size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1666 
1667   // Ensure that the sizes are properly aligned.
1668   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1669   Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1670   Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1671 
1672   // Reserve the maximum.
1673 
1674   // When compressed oops are enabled, the preferred heap base
1675   // is calculated by subtracting the requested size from the
1676   // 32Gb boundary and using the result as the base address for
1677   // heap reservation. If the requested size is not aligned to
1678   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1679   // into the ReservedHeapSpace constructor) then the actual
1680   // base of the reserved heap may end up differing from the
1681   // address that was requested (i.e. the preferred heap base).
1682   // If this happens then we could end up using a non-optimal
1683   // compressed oops mode.
1684 
1685   ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1686                                                      HeapAlignment);
1687 
1688   initialize_reserved_region(heap_rs);
1689 
1690   // Create the barrier set for the entire reserved region.
1691   G1CardTable* ct = new G1CardTable(heap_rs.region());
1692   ct->initialize();
1693   G1BarrierSet* bs = new G1BarrierSet(ct);
1694   bs->initialize();
1695   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1696   BarrierSet::set_barrier_set(bs);
1697   _card_table = ct;
1698 
1699   {
1700     G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1701     satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1702     satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1703   }
1704 
1705   // Create the hot card cache.
1706   _hot_card_cache = new G1HotCardCache(this);
1707 
1708   // Carve out the G1 part of the heap.
1709   ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1710   size_t page_size = actual_reserved_page_size(heap_rs);
1711   G1RegionToSpaceMapper* heap_storage =
1712     G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1713                                               g1_rs.size(),
1714                                               page_size,
1715                                               HeapRegion::GrainBytes,
1716                                               1,
1717                                               mtJavaHeap);
1718   if(heap_storage == NULL) {
1719     vm_shutdown_during_initialization("Could not initialize G1 heap");
1720     return JNI_ERR;
1721   }
1722 
1723   os::trace_page_sizes("Heap",
1724                        MinHeapSize,
1725                        reserved_byte_size,
1726                        page_size,
1727                        heap_rs.base(),
1728                        heap_rs.size());
1729   heap_storage->set_mapping_changed_listener(&_listener);
1730 
1731   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1732   G1RegionToSpaceMapper* bot_storage =
1733     create_aux_memory_mapper("Block Offset Table",
1734                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1735                              G1BlockOffsetTable::heap_map_factor());
1736 
1737   G1RegionToSpaceMapper* cardtable_storage =
1738     create_aux_memory_mapper("Card Table",
1739                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1740                              G1CardTable::heap_map_factor());
1741 
1742   G1RegionToSpaceMapper* card_counts_storage =
1743     create_aux_memory_mapper("Card Counts Table",
1744                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1745                              G1CardCounts::heap_map_factor());
1746 
1747   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1748   G1RegionToSpaceMapper* prev_bitmap_storage =
1749     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1750   G1RegionToSpaceMapper* next_bitmap_storage =
1751     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1752 
1753   _hrm = HeapRegionManager::create_manager(this);
1754 
1755   _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1756   _card_table->initialize(cardtable_storage);
1757 
1758   // Do later initialization work for concurrent refinement.
1759   _hot_card_cache->initialize(card_counts_storage);
1760 
1761   // 6843694 - ensure that the maximum region index can fit
1762   // in the remembered set structures.
1763   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1764   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1765 
1766   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1767   // start within the first card.
1768   guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1769   // Also create a G1 rem set.
1770   _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1771   _rem_set->initialize(max_reserved_capacity(), max_regions());
1772 
1773   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1774   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1775   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1776             "too many cards per region");
1777 
1778   FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1779 
1780   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1781 
1782   {
1783     HeapWord* start = _hrm->reserved().start();
1784     HeapWord* end = _hrm->reserved().end();
1785     size_t granularity = HeapRegion::GrainBytes;
1786 
1787     _region_attr.initialize(start, end, granularity);
1788     _humongous_reclaim_candidates.initialize(start, end, granularity);
1789   }
1790 
1791   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1792                           true /* are_GC_task_threads */,
1793                           false /* are_ConcurrentGC_threads */);
1794   if (_workers == NULL) {
1795     return JNI_ENOMEM;
1796   }
1797   _workers->initialize_workers();
1798 
1799   _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1800 
1801   // Create the G1ConcurrentMark data structure and thread.
1802   // (Must do this late, so that "max_regions" is defined.)
1803   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1804   if (_cm == NULL || !_cm->completed_initialization()) {
1805     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1806     return JNI_ENOMEM;
1807   }
1808   _cm_thread = _cm->cm_thread();
1809 
1810   // Now expand into the initial heap size.
1811   if (!expand(init_byte_size, _workers)) {
1812     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1813     return JNI_ENOMEM;
1814   }
1815 
1816   // Perform any initialization actions delegated to the policy.
1817   policy()->init(this, &_collection_set);
1818 
1819   jint ecode = initialize_concurrent_refinement();
1820   if (ecode != JNI_OK) {
1821     return ecode;
1822   }
1823 
1824   ecode = initialize_young_gen_sampling_thread();
1825   if (ecode != JNI_OK) {
1826     return ecode;
1827   }
1828 
1829   {
1830     G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1831     dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1832     dcqs.set_max_cards(concurrent_refine()->red_zone());
1833   }
1834 
1835   // Here we allocate the dummy HeapRegion that is required by the
1836   // G1AllocRegion class.
1837   HeapRegion* dummy_region = _hrm->get_dummy_region();
1838 
1839   // We'll re-use the same region whether the alloc region will
1840   // require BOT updates or not and, if it doesn't, then a non-young
1841   // region will complain that it cannot support allocations without
1842   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1843   dummy_region->set_eden();
1844   // Make sure it's full.
1845   dummy_region->set_top(dummy_region->end());
1846   G1AllocRegion::setup(this, dummy_region);
1847 
1848   _allocator->init_mutator_alloc_regions();
1849 
1850   // Do create of the monitoring and management support so that
1851   // values in the heap have been properly initialized.
1852   _g1mm = new G1MonitoringSupport(this);
1853 
1854   G1StringDedup::initialize();
1855 
1856   _preserved_marks_set.init(ParallelGCThreads);
1857 
1858   _collection_set.initialize(max_regions());
1859 
1860   return JNI_OK;
1861 }
1862 
1863 void G1CollectedHeap::stop() {
1864   // Stop all concurrent threads. We do this to make sure these threads
1865   // do not continue to execute and access resources (e.g. logging)
1866   // that are destroyed during shutdown.
1867   _cr->stop();
1868   _young_gen_sampling_thread->stop();
1869   _cm_thread->stop();
1870   if (G1StringDedup::is_enabled()) {
1871     G1StringDedup::stop();
1872   }
1873 }
1874 
1875 void G1CollectedHeap::safepoint_synchronize_begin() {
1876   SuspendibleThreadSet::synchronize();
1877 }
1878 
1879 void G1CollectedHeap::safepoint_synchronize_end() {
1880   SuspendibleThreadSet::desynchronize();
1881 }
1882 
1883 void G1CollectedHeap::post_initialize() {
1884   CollectedHeap::post_initialize();
1885   ref_processing_init();
1886 }
1887 
1888 void G1CollectedHeap::ref_processing_init() {
1889   // Reference processing in G1 currently works as follows:
1890   //
1891   // * There are two reference processor instances. One is
1892   //   used to record and process discovered references
1893   //   during concurrent marking; the other is used to
1894   //   record and process references during STW pauses
1895   //   (both full and incremental).
1896   // * Both ref processors need to 'span' the entire heap as
1897   //   the regions in the collection set may be dotted around.
1898   //
1899   // * For the concurrent marking ref processor:
1900   //   * Reference discovery is enabled at initial marking.
1901   //   * Reference discovery is disabled and the discovered
1902   //     references processed etc during remarking.
1903   //   * Reference discovery is MT (see below).
1904   //   * Reference discovery requires a barrier (see below).
1905   //   * Reference processing may or may not be MT
1906   //     (depending on the value of ParallelRefProcEnabled
1907   //     and ParallelGCThreads).
1908   //   * A full GC disables reference discovery by the CM
1909   //     ref processor and abandons any entries on it's
1910   //     discovered lists.
1911   //
1912   // * For the STW processor:
1913   //   * Non MT discovery is enabled at the start of a full GC.
1914   //   * Processing and enqueueing during a full GC is non-MT.
1915   //   * During a full GC, references are processed after marking.
1916   //
1917   //   * Discovery (may or may not be MT) is enabled at the start
1918   //     of an incremental evacuation pause.
1919   //   * References are processed near the end of a STW evacuation pause.
1920   //   * For both types of GC:
1921   //     * Discovery is atomic - i.e. not concurrent.
1922   //     * Reference discovery will not need a barrier.
1923 
1924   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1925 
1926   // Concurrent Mark ref processor
1927   _ref_processor_cm =
1928     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1929                            mt_processing,                                  // mt processing
1930                            ParallelGCThreads,                              // degree of mt processing
1931                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1932                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1933                            false,                                          // Reference discovery is not atomic
1934                            &_is_alive_closure_cm,                          // is alive closure
1935                            true);                                          // allow changes to number of processing threads
1936 
1937   // STW ref processor
1938   _ref_processor_stw =
1939     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1940                            mt_processing,                        // mt processing
1941                            ParallelGCThreads,                    // degree of mt processing
1942                            (ParallelGCThreads > 1),              // mt discovery
1943                            ParallelGCThreads,                    // degree of mt discovery
1944                            true,                                 // Reference discovery is atomic
1945                            &_is_alive_closure_stw,               // is alive closure
1946                            true);                                // allow changes to number of processing threads
1947 }
1948 
1949 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1950   return &_soft_ref_policy;
1951 }
1952 
1953 size_t G1CollectedHeap::capacity() const {
1954   return _hrm->length() * HeapRegion::GrainBytes;
1955 }
1956 
1957 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1958   return _hrm->total_free_bytes();
1959 }
1960 
1961 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1962   _hot_card_cache->drain(cl, worker_id);
1963 }
1964 
1965 // Computes the sum of the storage used by the various regions.
1966 size_t G1CollectedHeap::used() const {
1967   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1968   if (_archive_allocator != NULL) {
1969     result += _archive_allocator->used();
1970   }
1971   return result;
1972 }
1973 
1974 size_t G1CollectedHeap::used_unlocked() const {
1975   return _summary_bytes_used;
1976 }
1977 
1978 class SumUsedClosure: public HeapRegionClosure {
1979   size_t _used;
1980 public:
1981   SumUsedClosure() : _used(0) {}
1982   bool do_heap_region(HeapRegion* r) {
1983     _used += r->used();
1984     return false;
1985   }
1986   size_t result() { return _used; }
1987 };
1988 
1989 size_t G1CollectedHeap::recalculate_used() const {
1990   SumUsedClosure blk;
1991   heap_region_iterate(&blk);
1992   return blk.result();
1993 }
1994 
1995 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1996   switch (cause) {
1997     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1998     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1999     case GCCause::_wb_conc_mark:                        return true;
2000     default :                                           return false;
2001   }
2002 }
2003 
2004 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2005   switch (cause) {
2006     case GCCause::_g1_humongous_allocation: return true;
2007     case GCCause::_g1_periodic_collection:  return G1PeriodicGCInvokesConcurrent;
2008     default:                                return is_user_requested_concurrent_full_gc(cause);
2009   }
2010 }
2011 
2012 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2013   if (policy()->force_upgrade_to_full()) {
2014     return true;
2015   } else if (should_do_concurrent_full_gc(_gc_cause)) {
2016     return false;
2017   } else if (has_regions_left_for_allocation()) {
2018     return false;
2019   } else {
2020     return true;
2021   }
2022 }
2023 
2024 #ifndef PRODUCT
2025 void G1CollectedHeap::allocate_dummy_regions() {
2026   // Let's fill up most of the region
2027   size_t word_size = HeapRegion::GrainWords - 1024;
2028   // And as a result the region we'll allocate will be humongous.
2029   guarantee(is_humongous(word_size), "sanity");
2030 
2031   // _filler_array_max_size is set to humongous object threshold
2032   // but temporarily change it to use CollectedHeap::fill_with_object().
2033   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2034 
2035   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2036     // Let's use the existing mechanism for the allocation
2037     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2038     if (dummy_obj != NULL) {
2039       MemRegion mr(dummy_obj, word_size);
2040       CollectedHeap::fill_with_object(mr);
2041     } else {
2042       // If we can't allocate once, we probably cannot allocate
2043       // again. Let's get out of the loop.
2044       break;
2045     }
2046   }
2047 }
2048 #endif // !PRODUCT
2049 
2050 void G1CollectedHeap::increment_old_marking_cycles_started() {
2051   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2052          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2053          "Wrong marking cycle count (started: %d, completed: %d)",
2054          _old_marking_cycles_started, _old_marking_cycles_completed);
2055 
2056   _old_marking_cycles_started++;
2057 }
2058 
2059 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2060   MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
2061 
2062   // We assume that if concurrent == true, then the caller is a
2063   // concurrent thread that was joined the Suspendible Thread
2064   // Set. If there's ever a cheap way to check this, we should add an
2065   // assert here.
2066 
2067   // Given that this method is called at the end of a Full GC or of a
2068   // concurrent cycle, and those can be nested (i.e., a Full GC can
2069   // interrupt a concurrent cycle), the number of full collections
2070   // completed should be either one (in the case where there was no
2071   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2072   // behind the number of full collections started.
2073 
2074   // This is the case for the inner caller, i.e. a Full GC.
2075   assert(concurrent ||
2076          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2077          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2078          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2079          "is inconsistent with _old_marking_cycles_completed = %u",
2080          _old_marking_cycles_started, _old_marking_cycles_completed);
2081 
2082   // This is the case for the outer caller, i.e. the concurrent cycle.
2083   assert(!concurrent ||
2084          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2085          "for outer caller (concurrent cycle): "
2086          "_old_marking_cycles_started = %u "
2087          "is inconsistent with _old_marking_cycles_completed = %u",
2088          _old_marking_cycles_started, _old_marking_cycles_completed);
2089 
2090   _old_marking_cycles_completed += 1;
2091 
2092   // We need to clear the "in_progress" flag in the CM thread before
2093   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2094   // is set) so that if a waiter requests another System.gc() it doesn't
2095   // incorrectly see that a marking cycle is still in progress.
2096   if (concurrent) {
2097     _cm_thread->set_idle();
2098   }
2099 
2100   // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2101   // for a full GC to finish that their wait is over.
2102   ml.notify_all();
2103 }
2104 
2105 void G1CollectedHeap::collect(GCCause::Cause cause) {
2106   try_collect(cause);
2107 }
2108 
2109 // Return true if (x < y) with allowance for wraparound.
2110 static bool gc_counter_less_than(uint x, uint y) {
2111   return (x - y) > (UINT_MAX/2);
2112 }
2113 
2114 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2115 // Macro so msg printing is format-checked.
2116 #define LOG_COLLECT_CONCURRENTLY(cause, ...)                            \
2117   do {                                                                  \
2118     LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt;                   \
2119     if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) {                     \
2120       ResourceMark rm; /* For thread name. */                           \
2121       LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2122       LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2123                                        Thread::current()->name(),       \
2124                                        GCCause::to_string(cause));      \
2125       LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__);                    \
2126     }                                                                   \
2127   } while (0)
2128 
2129 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2130   LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2131 
2132 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2133                                                uint gc_counter,
2134                                                uint old_marking_started_before) {
2135   assert_heap_not_locked();
2136   assert(should_do_concurrent_full_gc(cause),
2137          "Non-concurrent cause %s", GCCause::to_string(cause));
2138 
2139   for (uint i = 1; true; ++i) {
2140     // Try to schedule an initial-mark evacuation pause that will
2141     // start a concurrent cycle.
2142     LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2143     VM_G1TryInitiateConcMark op(gc_counter,
2144                                 cause,
2145                                 policy()->max_pause_time_ms());
2146     VMThread::execute(&op);
2147 
2148     // Request is trivially finished.
2149     if (cause == GCCause::_g1_periodic_collection) {
2150       LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2151       return op.gc_succeeded();
2152     }
2153 
2154     // If VMOp skipped initiating concurrent marking cycle because
2155     // we're terminating, then we're done.
2156     if (op.terminating()) {
2157       LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2158       return false;
2159     }
2160 
2161     // Lock to get consistent set of values.
2162     uint old_marking_started_after;
2163     uint old_marking_completed_after;
2164     {
2165       MutexLocker ml(Heap_lock);
2166       // Update gc_counter for retrying VMOp if needed. Captured here to be
2167       // consistent with the values we use below for termination tests.  If
2168       // a retry is needed after a possible wait, and another collection
2169       // occurs in the meantime, it will cause our retry to be skipped and
2170       // we'll recheck for termination with updated conditions from that
2171       // more recent collection.  That's what we want, rather than having
2172       // our retry possibly perform an unnecessary collection.
2173       gc_counter = total_collections();
2174       old_marking_started_after = _old_marking_cycles_started;
2175       old_marking_completed_after = _old_marking_cycles_completed;
2176     }
2177 
2178     if (!GCCause::is_user_requested_gc(cause)) {
2179       // For an "automatic" (not user-requested) collection, we just need to
2180       // ensure that progress is made.
2181       //
2182       // Request is finished if any of
2183       // (1) the VMOp successfully performed a GC,
2184       // (2) a concurrent cycle was already in progress,
2185       // (3) a new cycle was started (by this thread or some other), or
2186       // (4) a Full GC was performed.
2187       // Cases (3) and (4) are detected together by a change to
2188       // _old_marking_cycles_started.
2189       //
2190       // Note that (1) does not imply (3).  If we're still in the mixed
2191       // phase of an earlier concurrent collection, the request to make the
2192       // collection an initial-mark won't be honored.  If we don't check for
2193       // both conditions we'll spin doing back-to-back collections.
2194       if (op.gc_succeeded() ||
2195           op.cycle_already_in_progress() ||
2196           (old_marking_started_before != old_marking_started_after)) {
2197         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2198         return true;
2199       }
2200     } else {                    // User-requested GC.
2201       // For a user-requested collection, we want to ensure that a complete
2202       // full collection has been performed before returning, but without
2203       // waiting for more than needed.
2204 
2205       // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2206       // new cycle was started.  That's good, because it's not clear what we
2207       // should do otherwise.  Trying again just does back to back GCs.
2208       // Can't wait for someone else to start a cycle.  And returning fails
2209       // to meet the goal of ensuring a full collection was performed.
2210       assert(!op.gc_succeeded() ||
2211              (old_marking_started_before != old_marking_started_after),
2212              "invariant: succeeded %s, started before %u, started after %u",
2213              BOOL_TO_STR(op.gc_succeeded()),
2214              old_marking_started_before, old_marking_started_after);
2215 
2216       // Request is finished if a full collection (concurrent or stw)
2217       // was started after this request and has completed, e.g.
2218       // started_before < completed_after.
2219       if (gc_counter_less_than(old_marking_started_before,
2220                                old_marking_completed_after)) {
2221         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2222         return true;
2223       }
2224 
2225       if (old_marking_started_after != old_marking_completed_after) {
2226         // If there is an in-progress cycle (possibly started by us), then
2227         // wait for that cycle to complete, e.g.
2228         // while completed_now < started_after.
2229         LOG_COLLECT_CONCURRENTLY(cause, "wait");
2230         MonitorLocker ml(G1OldGCCount_lock);
2231         while (gc_counter_less_than(_old_marking_cycles_completed,
2232                                     old_marking_started_after)) {
2233           ml.wait();
2234         }
2235         // Request is finished if the collection we just waited for was
2236         // started after this request.
2237         if (old_marking_started_before != old_marking_started_after) {
2238           LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2239           return true;
2240         }
2241       }
2242 
2243       // If VMOp was successful then it started a new cycle that the above
2244       // wait &etc should have recognized as finishing this request.  This
2245       // differs from a non-user-request, where gc_succeeded does not imply
2246       // a new cycle was started.
2247       assert(!op.gc_succeeded(), "invariant");
2248 
2249       // If VMOp failed because a cycle was already in progress, it is now
2250       // complete.  But it didn't finish this user-requested GC, so try
2251       // again.
2252       if (op.cycle_already_in_progress()) {
2253         LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2254         continue;
2255       }
2256     }
2257 
2258     // Collection failed and should be retried.
2259     assert(op.transient_failure(), "invariant");
2260 
2261     // If GCLocker is active, wait until clear before retrying.
2262     if (GCLocker::is_active_and_needs_gc()) {
2263       LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2264       GCLocker::stall_until_clear();
2265     }
2266 
2267     LOG_COLLECT_CONCURRENTLY(cause, "retry");
2268   }
2269 }
2270 
2271 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2272   assert_heap_not_locked();
2273 
2274   // Lock to get consistent set of values.
2275   uint gc_count_before;
2276   uint full_gc_count_before;
2277   uint old_marking_started_before;
2278   {
2279     MutexLocker ml(Heap_lock);
2280     gc_count_before = total_collections();
2281     full_gc_count_before = total_full_collections();
2282     old_marking_started_before = _old_marking_cycles_started;
2283   }
2284 
2285   if (should_do_concurrent_full_gc(cause)) {
2286     return try_collect_concurrently(cause,
2287                                     gc_count_before,
2288                                     old_marking_started_before);
2289   } else if (GCLocker::should_discard(cause, gc_count_before)) {
2290     // Indicate failure to be consistent with VMOp failure due to
2291     // another collection slipping in after our gc_count but before
2292     // our request is processed.
2293     return false;
2294   } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2295              DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2296 
2297     // Schedule a standard evacuation pause. We're setting word_size
2298     // to 0 which means that we are not requesting a post-GC allocation.
2299     VM_G1CollectForAllocation op(0,     /* word_size */
2300                                  gc_count_before,
2301                                  cause,
2302                                  policy()->max_pause_time_ms());
2303     VMThread::execute(&op);
2304     return op.gc_succeeded();
2305   } else {
2306     // Schedule a Full GC.
2307     VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2308     VMThread::execute(&op);
2309     return op.gc_succeeded();
2310   }
2311 }
2312 
2313 bool G1CollectedHeap::is_in(const void* p) const {
2314   if (_hrm->reserved().contains(p)) {
2315     // Given that we know that p is in the reserved space,
2316     // heap_region_containing() should successfully
2317     // return the containing region.
2318     HeapRegion* hr = heap_region_containing(p);
2319     return hr->is_in(p);
2320   } else {
2321     return false;
2322   }
2323 }
2324 
2325 #ifdef ASSERT
2326 bool G1CollectedHeap::is_in_exact(const void* p) const {
2327   bool contains = reserved_region().contains(p);
2328   bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2329   if (contains && available) {
2330     return true;
2331   } else {
2332     return false;
2333   }
2334 }
2335 #endif
2336 
2337 // Iteration functions.
2338 
2339 // Iterates an ObjectClosure over all objects within a HeapRegion.
2340 
2341 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2342   ObjectClosure* _cl;
2343 public:
2344   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2345   bool do_heap_region(HeapRegion* r) {
2346     if (!r->is_continues_humongous()) {
2347       r->object_iterate(_cl);
2348     }
2349     return false;
2350   }
2351 };
2352 
2353 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2354   IterateObjectClosureRegionClosure blk(cl);
2355   heap_region_iterate(&blk);
2356 }
2357 
2358 void G1CollectedHeap::keep_alive(oop obj) {
2359   G1BarrierSet::enqueue(obj);
2360 }
2361 
2362 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2363   _hrm->iterate(cl);
2364 }
2365 
2366 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2367                                                                  HeapRegionClaimer *hrclaimer,
2368                                                                  uint worker_id) const {
2369   _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2370 }
2371 
2372 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2373                                                          HeapRegionClaimer *hrclaimer) const {
2374   _hrm->par_iterate(cl, hrclaimer, 0);
2375 }
2376 
2377 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2378   _collection_set.iterate(cl);
2379 }
2380 
2381 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2382   _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2383 }
2384 
2385 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2386   _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2387 }
2388 
2389 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2390   HeapRegion* hr = heap_region_containing(addr);
2391   return hr->block_start(addr);
2392 }
2393 
2394 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2395   HeapRegion* hr = heap_region_containing(addr);
2396   return hr->block_is_obj(addr);
2397 }
2398 
2399 bool G1CollectedHeap::supports_tlab_allocation() const {
2400   return true;
2401 }
2402 
2403 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2404   return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2405 }
2406 
2407 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2408   return _eden.length() * HeapRegion::GrainBytes;
2409 }
2410 
2411 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2412 // must be equal to the humongous object limit.
2413 size_t G1CollectedHeap::max_tlab_size() const {
2414   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2415 }
2416 
2417 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2418   return _allocator->unsafe_max_tlab_alloc();
2419 }
2420 
2421 size_t G1CollectedHeap::max_capacity() const {
2422   return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2423 }
2424 
2425 size_t G1CollectedHeap::max_reserved_capacity() const {
2426   return _hrm->max_length() * HeapRegion::GrainBytes;
2427 }
2428 
2429 jlong G1CollectedHeap::millis_since_last_gc() {
2430   // See the notes in GenCollectedHeap::millis_since_last_gc()
2431   // for more information about the implementation.
2432   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2433                   _policy->collection_pause_end_millis();
2434   if (ret_val < 0) {
2435     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2436       ". returning zero instead.", ret_val);
2437     return 0;
2438   }
2439   return ret_val;
2440 }
2441 
2442 void G1CollectedHeap::deduplicate_string(oop str) {
2443   assert(java_lang_String::is_instance(str), "invariant");
2444 
2445   if (G1StringDedup::is_enabled()) {
2446     G1StringDedup::deduplicate(str);
2447   }
2448 }
2449 
2450 void G1CollectedHeap::prepare_for_verify() {
2451   _verifier->prepare_for_verify();
2452 }
2453 
2454 void G1CollectedHeap::verify(VerifyOption vo) {
2455   _verifier->verify(vo);
2456 }
2457 
2458 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2459   return true;
2460 }
2461 
2462 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2463   return _cm_thread->request_concurrent_phase(phase);
2464 }
2465 
2466 bool G1CollectedHeap::is_heterogeneous_heap() const {
2467   return G1Arguments::is_heterogeneous_heap();
2468 }
2469 
2470 class PrintRegionClosure: public HeapRegionClosure {
2471   outputStream* _st;
2472 public:
2473   PrintRegionClosure(outputStream* st) : _st(st) {}
2474   bool do_heap_region(HeapRegion* r) {
2475     r->print_on(_st);
2476     return false;
2477   }
2478 };
2479 
2480 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2481                                        const HeapRegion* hr,
2482                                        const VerifyOption vo) const {
2483   switch (vo) {
2484   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2485   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2486   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2487   default:                            ShouldNotReachHere();
2488   }
2489   return false; // keep some compilers happy
2490 }
2491 
2492 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2493                                        const VerifyOption vo) const {
2494   switch (vo) {
2495   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2496   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2497   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2498   default:                            ShouldNotReachHere();
2499   }
2500   return false; // keep some compilers happy
2501 }
2502 
2503 void G1CollectedHeap::print_heap_regions() const {
2504   LogTarget(Trace, gc, heap, region) lt;
2505   if (lt.is_enabled()) {
2506     LogStream ls(lt);
2507     print_regions_on(&ls);
2508   }
2509 }
2510 
2511 void G1CollectedHeap::print_on(outputStream* st) const {
2512   st->print(" %-20s", "garbage-first heap");
2513   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2514             capacity()/K, used_unlocked()/K);
2515   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2516             p2i(_hrm->reserved().start()),
2517             p2i(_hrm->reserved().end()));
2518   st->cr();
2519   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2520   uint young_regions = young_regions_count();
2521   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2522             (size_t) young_regions * HeapRegion::GrainBytes / K);
2523   uint survivor_regions = survivor_regions_count();
2524   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2525             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2526   st->cr();
2527   if (_numa->is_enabled()) {
2528     uint num_nodes = _numa->num_active_nodes();
2529     st->print("  remaining free region(s) on each NUMA node: ");
2530     const int* node_ids = _numa->node_ids();
2531     for (uint node_index = 0; node_index < num_nodes; node_index++) {
2532       st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index));
2533     }
2534     st->cr();
2535   }
2536   MetaspaceUtils::print_on(st);
2537 }
2538 
2539 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2540   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2541                "HS=humongous(starts), HC=humongous(continues), "
2542                "CS=collection set, F=free, "
2543                "OA=open archive, CA=closed archive, "
2544                "TAMS=top-at-mark-start (previous, next)");
2545   PrintRegionClosure blk(st);
2546   heap_region_iterate(&blk);
2547 }
2548 
2549 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2550   print_on(st);
2551 
2552   // Print the per-region information.
2553   print_regions_on(st);
2554 }
2555 
2556 void G1CollectedHeap::print_on_error(outputStream* st) const {
2557   this->CollectedHeap::print_on_error(st);
2558 
2559   if (_cm != NULL) {
2560     st->cr();
2561     _cm->print_on_error(st);
2562   }
2563 }
2564 
2565 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2566   workers()->print_worker_threads_on(st);
2567   _cm_thread->print_on(st);
2568   st->cr();
2569   _cm->print_worker_threads_on(st);
2570   _cr->print_threads_on(st);
2571   _young_gen_sampling_thread->print_on(st);
2572   if (G1StringDedup::is_enabled()) {
2573     G1StringDedup::print_worker_threads_on(st);
2574   }
2575 }
2576 
2577 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2578   workers()->threads_do(tc);
2579   tc->do_thread(_cm_thread);
2580   _cm->threads_do(tc);
2581   _cr->threads_do(tc);
2582   tc->do_thread(_young_gen_sampling_thread);
2583   if (G1StringDedup::is_enabled()) {
2584     G1StringDedup::threads_do(tc);
2585   }
2586 }
2587 
2588 void G1CollectedHeap::print_tracing_info() const {
2589   rem_set()->print_summary_info();
2590   concurrent_mark()->print_summary_info();
2591 }
2592 
2593 #ifndef PRODUCT
2594 // Helpful for debugging RSet issues.
2595 
2596 class PrintRSetsClosure : public HeapRegionClosure {
2597 private:
2598   const char* _msg;
2599   size_t _occupied_sum;
2600 
2601 public:
2602   bool do_heap_region(HeapRegion* r) {
2603     HeapRegionRemSet* hrrs = r->rem_set();
2604     size_t occupied = hrrs->occupied();
2605     _occupied_sum += occupied;
2606 
2607     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2608     if (occupied == 0) {
2609       tty->print_cr("  RSet is empty");
2610     } else {
2611       hrrs->print();
2612     }
2613     tty->print_cr("----------");
2614     return false;
2615   }
2616 
2617   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2618     tty->cr();
2619     tty->print_cr("========================================");
2620     tty->print_cr("%s", msg);
2621     tty->cr();
2622   }
2623 
2624   ~PrintRSetsClosure() {
2625     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2626     tty->print_cr("========================================");
2627     tty->cr();
2628   }
2629 };
2630 
2631 void G1CollectedHeap::print_cset_rsets() {
2632   PrintRSetsClosure cl("Printing CSet RSets");
2633   collection_set_iterate_all(&cl);
2634 }
2635 
2636 void G1CollectedHeap::print_all_rsets() {
2637   PrintRSetsClosure cl("Printing All RSets");;
2638   heap_region_iterate(&cl);
2639 }
2640 #endif // PRODUCT
2641 
2642 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2643   return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2644 }
2645 
2646 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2647 
2648   size_t eden_used_bytes = _eden.used_bytes();
2649   size_t survivor_used_bytes = _survivor.used_bytes();
2650   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2651 
2652   size_t eden_capacity_bytes =
2653     (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2654 
2655   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2656   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2657                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2658 }
2659 
2660 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2661   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2662                        stats->unused(), stats->used(), stats->region_end_waste(),
2663                        stats->regions_filled(), stats->direct_allocated(),
2664                        stats->failure_used(), stats->failure_waste());
2665 }
2666 
2667 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2668   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2669   gc_tracer->report_gc_heap_summary(when, heap_summary);
2670 
2671   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2672   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2673 }
2674 
2675 G1CollectedHeap* G1CollectedHeap::heap() {
2676   CollectedHeap* heap = Universe::heap();
2677   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2678   assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2679   return (G1CollectedHeap*)heap;
2680 }
2681 
2682 void G1CollectedHeap::gc_prologue(bool full) {
2683   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2684 
2685   // This summary needs to be printed before incrementing total collections.
2686   rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2687 
2688   // Update common counters.
2689   increment_total_collections(full /* full gc */);
2690   if (full || collector_state()->in_initial_mark_gc()) {
2691     increment_old_marking_cycles_started();
2692   }
2693 
2694   // Fill TLAB's and such
2695   double start = os::elapsedTime();
2696   ensure_parsability(true);
2697   phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2698 }
2699 
2700 void G1CollectedHeap::gc_epilogue(bool full) {
2701   // Update common counters.
2702   if (full) {
2703     // Update the number of full collections that have been completed.
2704     increment_old_marking_cycles_completed(false /* concurrent */);
2705   }
2706 
2707   // We are at the end of the GC. Total collections has already been increased.
2708   rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2709 
2710   // FIXME: what is this about?
2711   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2712   // is set.
2713 #if COMPILER2_OR_JVMCI
2714   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2715 #endif
2716 
2717   double start = os::elapsedTime();
2718   resize_all_tlabs();
2719   phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2720 
2721   MemoryService::track_memory_usage();
2722   // We have just completed a GC. Update the soft reference
2723   // policy with the new heap occupancy
2724   Universe::update_heap_info_at_gc();
2725 
2726   // Print NUMA statistics.
2727   _numa->print_statistics();
2728 }
2729 
2730 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2731   LogTarget(Trace, gc, heap, verify) lt;
2732 
2733   if (lt.is_enabled()) {
2734     LogStream ls(lt);
2735     // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2736     G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2737     heap_region_iterate(&cl);
2738   }
2739 }
2740 
2741 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2742                                                uint gc_count_before,
2743                                                bool* succeeded,
2744                                                GCCause::Cause gc_cause) {
2745   assert_heap_not_locked_and_not_at_safepoint();
2746   VM_G1CollectForAllocation op(word_size,
2747                                gc_count_before,
2748                                gc_cause,
2749                                policy()->max_pause_time_ms());
2750   VMThread::execute(&op);
2751 
2752   HeapWord* result = op.result();
2753   bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2754   assert(result == NULL || ret_succeeded,
2755          "the result should be NULL if the VM did not succeed");
2756   *succeeded = ret_succeeded;
2757 
2758   assert_heap_not_locked();
2759   return result;
2760 }
2761 
2762 void G1CollectedHeap::do_concurrent_mark() {
2763   MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2764   if (!_cm_thread->in_progress()) {
2765     _cm_thread->set_started();
2766     CGC_lock->notify();
2767   }
2768 }
2769 
2770 size_t G1CollectedHeap::pending_card_num() {
2771   struct CountCardsClosure : public ThreadClosure {
2772     size_t _cards;
2773     CountCardsClosure() : _cards(0) {}
2774     virtual void do_thread(Thread* t) {
2775       _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2776     }
2777   } count_from_threads;
2778   Threads::threads_do(&count_from_threads);
2779 
2780   G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();


2781   return dcqs.num_cards() + count_from_threads._cards;
2782 }
2783 
2784 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2785   // We don't nominate objects with many remembered set entries, on
2786   // the assumption that such objects are likely still live.
2787   HeapRegionRemSet* rem_set = r->rem_set();
2788 
2789   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2790          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2791          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2792 }
2793 
2794 #ifndef PRODUCT
2795 void G1CollectedHeap::verify_region_attr_remset_update() {
2796   class VerifyRegionAttrRemSet : public HeapRegionClosure {
2797   public:
2798     virtual bool do_heap_region(HeapRegion* r) {
2799       G1CollectedHeap* g1h = G1CollectedHeap::heap();
2800       bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2801       assert(r->rem_set()->is_tracked() == needs_remset_update,
2802              "Region %u remset tracking status (%s) different to region attribute (%s)",
2803              r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2804       return false;
2805     }
2806   } cl;
2807   heap_region_iterate(&cl);
2808 }
2809 #endif
2810 
2811 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2812   public:
2813     bool do_heap_region(HeapRegion* hr) {
2814       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2815         hr->verify_rem_set();
2816       }
2817       return false;
2818     }
2819 };
2820 
2821 uint G1CollectedHeap::num_task_queues() const {
2822   return _task_queues->size();
2823 }
2824 
2825 #if TASKQUEUE_STATS
2826 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2827   st->print_raw_cr("GC Task Stats");
2828   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2829   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2830 }
2831 
2832 void G1CollectedHeap::print_taskqueue_stats() const {
2833   if (!log_is_enabled(Trace, gc, task, stats)) {
2834     return;
2835   }
2836   Log(gc, task, stats) log;
2837   ResourceMark rm;
2838   LogStream ls(log.trace());
2839   outputStream* st = &ls;
2840 
2841   print_taskqueue_stats_hdr(st);
2842 
2843   TaskQueueStats totals;
2844   const uint n = num_task_queues();
2845   for (uint i = 0; i < n; ++i) {
2846     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2847     totals += task_queue(i)->stats;
2848   }
2849   st->print_raw("tot "); totals.print(st); st->cr();
2850 
2851   DEBUG_ONLY(totals.verify());
2852 }
2853 
2854 void G1CollectedHeap::reset_taskqueue_stats() {
2855   const uint n = num_task_queues();
2856   for (uint i = 0; i < n; ++i) {
2857     task_queue(i)->stats.reset();
2858   }
2859 }
2860 #endif // TASKQUEUE_STATS
2861 
2862 void G1CollectedHeap::wait_for_root_region_scanning() {
2863   double scan_wait_start = os::elapsedTime();
2864   // We have to wait until the CM threads finish scanning the
2865   // root regions as it's the only way to ensure that all the
2866   // objects on them have been correctly scanned before we start
2867   // moving them during the GC.
2868   bool waited = _cm->root_regions()->wait_until_scan_finished();
2869   double wait_time_ms = 0.0;
2870   if (waited) {
2871     double scan_wait_end = os::elapsedTime();
2872     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2873   }
2874   phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2875 }
2876 
2877 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2878 private:
2879   G1HRPrinter* _hr_printer;
2880 public:
2881   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2882 
2883   virtual bool do_heap_region(HeapRegion* r) {
2884     _hr_printer->cset(r);
2885     return false;
2886   }
2887 };
2888 
2889 void G1CollectedHeap::start_new_collection_set() {
2890   double start = os::elapsedTime();
2891 
2892   collection_set()->start_incremental_building();
2893 
2894   clear_region_attr();
2895 
2896   guarantee(_eden.length() == 0, "eden should have been cleared");
2897   policy()->transfer_survivors_to_cset(survivor());
2898 
2899   // We redo the verification but now wrt to the new CSet which
2900   // has just got initialized after the previous CSet was freed.
2901   _cm->verify_no_collection_set_oops();
2902 
2903   phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2904 }
2905 
2906 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2907 
2908   _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2909   evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2910                                             collection_set()->optional_region_length());
2911 
2912   _cm->verify_no_collection_set_oops();
2913 
2914   if (_hr_printer.is_active()) {
2915     G1PrintCollectionSetClosure cl(&_hr_printer);
2916     _collection_set.iterate(&cl);
2917     _collection_set.iterate_optional(&cl);
2918   }
2919 }
2920 
2921 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2922   if (collector_state()->in_initial_mark_gc()) {
2923     return G1HeapVerifier::G1VerifyConcurrentStart;
2924   } else if (collector_state()->in_young_only_phase()) {
2925     return G1HeapVerifier::G1VerifyYoungNormal;
2926   } else {
2927     return G1HeapVerifier::G1VerifyMixed;
2928   }
2929 }
2930 
2931 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2932   if (VerifyRememberedSets) {
2933     log_info(gc, verify)("[Verifying RemSets before GC]");
2934     VerifyRegionRemSetClosure v_cl;
2935     heap_region_iterate(&v_cl);
2936   }
2937   _verifier->verify_before_gc(type);
2938   _verifier->check_bitmaps("GC Start");
2939   verify_numa_regions("GC Start");
2940 }
2941 
2942 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2943   if (VerifyRememberedSets) {
2944     log_info(gc, verify)("[Verifying RemSets after GC]");
2945     VerifyRegionRemSetClosure v_cl;
2946     heap_region_iterate(&v_cl);
2947   }
2948   _verifier->verify_after_gc(type);
2949   _verifier->check_bitmaps("GC End");
2950   verify_numa_regions("GC End");
2951 }
2952 
2953 void G1CollectedHeap::expand_heap_after_young_collection(){
2954   size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2955   if (expand_bytes > 0) {
2956     // No need for an ergo logging here,
2957     // expansion_amount() does this when it returns a value > 0.
2958     double expand_ms;
2959     if (!expand(expand_bytes, _workers, &expand_ms)) {
2960       // We failed to expand the heap. Cannot do anything about it.
2961     }
2962     phase_times()->record_expand_heap_time(expand_ms);
2963   }
2964 }
2965 
2966 const char* G1CollectedHeap::young_gc_name() const {
2967   if (collector_state()->in_initial_mark_gc()) {
2968     return "Pause Young (Concurrent Start)";
2969   } else if (collector_state()->in_young_only_phase()) {
2970     if (collector_state()->in_young_gc_before_mixed()) {
2971       return "Pause Young (Prepare Mixed)";
2972     } else {
2973       return "Pause Young (Normal)";
2974     }
2975   } else {
2976     return "Pause Young (Mixed)";
2977   }
2978 }
2979 
2980 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2981   assert_at_safepoint_on_vm_thread();
2982   guarantee(!is_gc_active(), "collection is not reentrant");
2983 
2984   if (GCLocker::check_active_before_gc()) {
2985     return false;
2986   }
2987 
2988   GCIdMark gc_id_mark;
2989 
2990   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2991   ResourceMark rm;
2992 
2993   policy()->note_gc_start();
2994 
2995   _gc_timer_stw->register_gc_start();
2996   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2997 
2998   wait_for_root_region_scanning();
2999 
3000   print_heap_before_gc();
3001   print_heap_regions();
3002   trace_heap_before_gc(_gc_tracer_stw);
3003 
3004   _verifier->verify_region_sets_optional();
3005   _verifier->verify_dirty_young_regions();
3006 
3007   // We should not be doing initial mark unless the conc mark thread is running
3008   if (!_cm_thread->should_terminate()) {
3009     // This call will decide whether this pause is an initial-mark
3010     // pause. If it is, in_initial_mark_gc() will return true
3011     // for the duration of this pause.
3012     policy()->decide_on_conc_mark_initiation();
3013   }
3014 
3015   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3016   assert(!collector_state()->in_initial_mark_gc() ||
3017          collector_state()->in_young_only_phase(), "sanity");
3018   // We also do not allow mixed GCs during marking.
3019   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3020 
3021   // Record whether this pause is an initial mark. When the current
3022   // thread has completed its logging output and it's safe to signal
3023   // the CM thread, the flag's value in the policy has been reset.
3024   bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3025   if (should_start_conc_mark) {
3026     _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3027   }
3028 
3029   // Inner scope for scope based logging, timers, and stats collection
3030   {
3031     G1EvacuationInfo evacuation_info;
3032 
3033     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3034 
3035     GCTraceCPUTime tcpu;
3036 
3037     GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3038 
3039     uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3040                                                             workers()->active_workers(),
3041                                                             Threads::number_of_non_daemon_threads());
3042     active_workers = workers()->update_active_workers(active_workers);
3043     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3044 
3045     G1MonitoringScope ms(g1mm(),
3046                          false /* full_gc */,
3047                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3048 
3049     G1HeapTransition heap_transition(this);
3050 
3051     {
3052       IsGCActiveMark x;
3053 
3054       gc_prologue(false);
3055 
3056       G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3057       verify_before_young_collection(verify_type);
3058 
3059       {
3060         // The elapsed time induced by the start time below deliberately elides
3061         // the possible verification above.
3062         double sample_start_time_sec = os::elapsedTime();
3063 
3064         // Please see comment in g1CollectedHeap.hpp and
3065         // G1CollectedHeap::ref_processing_init() to see how
3066         // reference processing currently works in G1.
3067         _ref_processor_stw->enable_discovery();
3068 
3069         // We want to temporarily turn off discovery by the
3070         // CM ref processor, if necessary, and turn it back on
3071         // on again later if we do. Using a scoped
3072         // NoRefDiscovery object will do this.
3073         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3074 
3075         policy()->record_collection_pause_start(sample_start_time_sec);
3076 
3077         // Forget the current allocation region (we might even choose it to be part
3078         // of the collection set!).
3079         _allocator->release_mutator_alloc_regions();
3080 
3081         calculate_collection_set(evacuation_info, target_pause_time_ms);
3082 
3083         G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3084         G1ParScanThreadStateSet per_thread_states(this,
3085                                                   &rdcqs,
3086                                                   workers()->active_workers(),
3087                                                   collection_set()->young_region_length(),
3088                                                   collection_set()->optional_region_length());
3089         pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3090 
3091         // Actually do the work...
3092         evacuate_initial_collection_set(&per_thread_states);
3093 
3094         if (_collection_set.optional_region_length() != 0) {
3095           evacuate_optional_collection_set(&per_thread_states);
3096         }
3097         post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3098 
3099         start_new_collection_set();
3100 
3101         _survivor_evac_stats.adjust_desired_plab_sz();
3102         _old_evac_stats.adjust_desired_plab_sz();
3103 
3104         if (should_start_conc_mark) {
3105           // We have to do this before we notify the CM threads that
3106           // they can start working to make sure that all the
3107           // appropriate initialization is done on the CM object.
3108           concurrent_mark()->post_initial_mark();
3109           // Note that we don't actually trigger the CM thread at
3110           // this point. We do that later when we're sure that
3111           // the current thread has completed its logging output.
3112         }
3113 
3114         allocate_dummy_regions();
3115 
3116         _allocator->init_mutator_alloc_regions();
3117 
3118         expand_heap_after_young_collection();
3119 
3120         double sample_end_time_sec = os::elapsedTime();
3121         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3122         policy()->record_collection_pause_end(pause_time_ms);
3123       }
3124 
3125       verify_after_young_collection(verify_type);
3126 
3127 #ifdef TRACESPINNING
3128       ParallelTaskTerminator::print_termination_counts();
3129 #endif
3130 
3131       gc_epilogue(false);
3132     }
3133 
3134     // Print the remainder of the GC log output.
3135     if (evacuation_failed()) {
3136       log_info(gc)("To-space exhausted");
3137     }
3138 
3139     policy()->print_phases();
3140     heap_transition.print();
3141 
3142     _hrm->verify_optional();
3143     _verifier->verify_region_sets_optional();
3144 
3145     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3146     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3147 
3148     print_heap_after_gc();
3149     print_heap_regions();
3150     trace_heap_after_gc(_gc_tracer_stw);
3151 
3152     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3153     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3154     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3155     // before any GC notifications are raised.
3156     g1mm()->update_sizes();
3157 
3158     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3159     _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3160     _gc_timer_stw->register_gc_end();
3161     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3162   }
3163   // It should now be safe to tell the concurrent mark thread to start
3164   // without its logging output interfering with the logging output
3165   // that came from the pause.
3166 
3167   if (should_start_conc_mark) {
3168     // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3169     // thread(s) could be running concurrently with us. Make sure that anything
3170     // after this point does not assume that we are the only GC thread running.
3171     // Note: of course, the actual marking work will not start until the safepoint
3172     // itself is released in SuspendibleThreadSet::desynchronize().
3173     do_concurrent_mark();
3174   }
3175 
3176   return true;
3177 }
3178 
3179 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3180   G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3181   workers()->run_task(&rsfp_task);
3182 }
3183 
3184 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3185   double remove_self_forwards_start = os::elapsedTime();
3186 
3187   remove_self_forwarding_pointers(rdcqs);
3188   _preserved_marks_set.restore(workers());
3189 
3190   phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3191 }
3192 
3193 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3194   if (!_evacuation_failed) {
3195     _evacuation_failed = true;
3196   }
3197 
3198   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3199   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3200 }
3201 
3202 bool G1ParEvacuateFollowersClosure::offer_termination() {
3203   EventGCPhaseParallel event;
3204   G1ParScanThreadState* const pss = par_scan_state();
3205   start_term_time();
3206   const bool res = terminator()->offer_termination();
3207   end_term_time();
3208   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3209   return res;
3210 }
3211 
3212 void G1ParEvacuateFollowersClosure::do_void() {
3213   EventGCPhaseParallel event;
3214   G1ParScanThreadState* const pss = par_scan_state();
3215   pss->trim_queue();
3216   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3217   do {
3218     EventGCPhaseParallel event;
3219     pss->steal_and_trim_queue(queues());
3220     event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3221   } while (!offer_termination());
3222 }
3223 
3224 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3225                                         bool class_unloading_occurred) {
3226   uint num_workers = workers()->active_workers();
3227   G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3228   workers()->run_task(&unlink_task);
3229 }
3230 
3231 // Clean string dedup data structures.
3232 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3233 // record the durations of the phases. Hence the almost-copy.
3234 class G1StringDedupCleaningTask : public AbstractGangTask {
3235   BoolObjectClosure* _is_alive;
3236   OopClosure* _keep_alive;
3237   G1GCPhaseTimes* _phase_times;
3238 
3239 public:
3240   G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3241                             OopClosure* keep_alive,
3242                             G1GCPhaseTimes* phase_times) :
3243     AbstractGangTask("Partial Cleaning Task"),
3244     _is_alive(is_alive),
3245     _keep_alive(keep_alive),
3246     _phase_times(phase_times)
3247   {
3248     assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3249     StringDedup::gc_prologue(true);
3250   }
3251 
3252   ~G1StringDedupCleaningTask() {
3253     StringDedup::gc_epilogue();
3254   }
3255 
3256   void work(uint worker_id) {
3257     StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3258     {
3259       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3260       StringDedupQueue::unlink_or_oops_do(&cl);
3261     }
3262     {
3263       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3264       StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3265     }
3266   }
3267 };
3268 
3269 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3270                                             OopClosure* keep_alive,
3271                                             G1GCPhaseTimes* phase_times) {
3272   G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3273   workers()->run_task(&cl);
3274 }
3275 
3276 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3277  private:
3278   G1RedirtyCardsQueueSet* _qset;
3279   G1CollectedHeap* _g1h;
3280   BufferNode* volatile _nodes;
3281 
3282   void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3283     size_t buffer_size = _qset->buffer_size();
3284     BufferNode* next = Atomic::load(&_nodes);
3285     while (next != NULL) {
3286       BufferNode* node = next;
3287       next = Atomic::cmpxchg(&_nodes, node, node->next());
3288       if (next == node) {
3289         cl->apply_to_buffer(node, buffer_size, worker_id);
3290         next = node->next();
3291       }
3292     }
3293   }
3294 
3295  public:
3296   G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3297     AbstractGangTask("Redirty Cards"),
3298     _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3299 
3300   virtual void work(uint worker_id) {
3301     G1GCPhaseTimes* p = _g1h->phase_times();
3302     G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3303 
3304     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3305     par_apply(&cl, worker_id);
3306 
3307     p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3308   }
3309 };
3310 
3311 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3312   double redirty_logged_cards_start = os::elapsedTime();
3313 
3314   G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3315   workers()->run_task(&redirty_task);
3316 
3317   G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3318   dcq.merge_bufferlists(rdcqs);
3319 
3320   phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3321 }
3322 
3323 // Weak Reference Processing support
3324 
3325 bool G1STWIsAliveClosure::do_object_b(oop p) {
3326   // An object is reachable if it is outside the collection set,
3327   // or is inside and copied.
3328   return !_g1h->is_in_cset(p) || p->is_forwarded();
3329 }
3330 
3331 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3332   assert(obj != NULL, "must not be NULL");
3333   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3334   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3335   // may falsely indicate that this is not the case here: however the collection set only
3336   // contains old regions when concurrent mark is not running.
3337   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3338 }
3339 
3340 // Non Copying Keep Alive closure
3341 class G1KeepAliveClosure: public OopClosure {
3342   G1CollectedHeap*_g1h;
3343 public:
3344   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3345   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3346   void do_oop(oop* p) {
3347     oop obj = *p;
3348     assert(obj != NULL, "the caller should have filtered out NULL values");
3349 
3350     const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3351     if (!region_attr.is_in_cset_or_humongous()) {
3352       return;
3353     }
3354     if (region_attr.is_in_cset()) {
3355       assert( obj->is_forwarded(), "invariant" );
3356       *p = obj->forwardee();
3357     } else {
3358       assert(!obj->is_forwarded(), "invariant" );
3359       assert(region_attr.is_humongous(),
3360              "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3361      _g1h->set_humongous_is_live(obj);
3362     }
3363   }
3364 };
3365 
3366 // Copying Keep Alive closure - can be called from both
3367 // serial and parallel code as long as different worker
3368 // threads utilize different G1ParScanThreadState instances
3369 // and different queues.
3370 
3371 class G1CopyingKeepAliveClosure: public OopClosure {
3372   G1CollectedHeap*         _g1h;
3373   G1ParScanThreadState*    _par_scan_state;
3374 
3375 public:
3376   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3377                             G1ParScanThreadState* pss):
3378     _g1h(g1h),
3379     _par_scan_state(pss)
3380   {}
3381 
3382   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3383   virtual void do_oop(      oop* p) { do_oop_work(p); }
3384 
3385   template <class T> void do_oop_work(T* p) {
3386     oop obj = RawAccess<>::oop_load(p);
3387 
3388     if (_g1h->is_in_cset_or_humongous(obj)) {
3389       // If the referent object has been forwarded (either copied
3390       // to a new location or to itself in the event of an
3391       // evacuation failure) then we need to update the reference
3392       // field and, if both reference and referent are in the G1
3393       // heap, update the RSet for the referent.
3394       //
3395       // If the referent has not been forwarded then we have to keep
3396       // it alive by policy. Therefore we have copy the referent.
3397       //
3398       // When the queue is drained (after each phase of reference processing)
3399       // the object and it's followers will be copied, the reference field set
3400       // to point to the new location, and the RSet updated.
3401       _par_scan_state->push_on_queue(p);
3402     }
3403   }
3404 };
3405 
3406 // Serial drain queue closure. Called as the 'complete_gc'
3407 // closure for each discovered list in some of the
3408 // reference processing phases.
3409 
3410 class G1STWDrainQueueClosure: public VoidClosure {
3411 protected:
3412   G1CollectedHeap* _g1h;
3413   G1ParScanThreadState* _par_scan_state;
3414 
3415   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3416 
3417 public:
3418   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3419     _g1h(g1h),
3420     _par_scan_state(pss)
3421   { }
3422 
3423   void do_void() {
3424     G1ParScanThreadState* const pss = par_scan_state();
3425     pss->trim_queue();
3426   }
3427 };
3428 
3429 // Parallel Reference Processing closures
3430 
3431 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3432 // processing during G1 evacuation pauses.
3433 
3434 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3435 private:
3436   G1CollectedHeap*          _g1h;
3437   G1ParScanThreadStateSet*  _pss;
3438   RefToScanQueueSet*        _queues;
3439   WorkGang*                 _workers;
3440 
3441 public:
3442   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3443                            G1ParScanThreadStateSet* per_thread_states,
3444                            WorkGang* workers,
3445                            RefToScanQueueSet *task_queues) :
3446     _g1h(g1h),
3447     _pss(per_thread_states),
3448     _queues(task_queues),
3449     _workers(workers)
3450   {
3451     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3452   }
3453 
3454   // Executes the given task using concurrent marking worker threads.
3455   virtual void execute(ProcessTask& task, uint ergo_workers);
3456 };
3457 
3458 // Gang task for possibly parallel reference processing
3459 
3460 class G1STWRefProcTaskProxy: public AbstractGangTask {
3461   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3462   ProcessTask&     _proc_task;
3463   G1CollectedHeap* _g1h;
3464   G1ParScanThreadStateSet* _pss;
3465   RefToScanQueueSet* _task_queues;
3466   ParallelTaskTerminator* _terminator;
3467 
3468 public:
3469   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3470                         G1CollectedHeap* g1h,
3471                         G1ParScanThreadStateSet* per_thread_states,
3472                         RefToScanQueueSet *task_queues,
3473                         ParallelTaskTerminator* terminator) :
3474     AbstractGangTask("Process reference objects in parallel"),
3475     _proc_task(proc_task),
3476     _g1h(g1h),
3477     _pss(per_thread_states),
3478     _task_queues(task_queues),
3479     _terminator(terminator)
3480   {}
3481 
3482   virtual void work(uint worker_id) {
3483     // The reference processing task executed by a single worker.
3484     ResourceMark rm;
3485     HandleMark   hm;
3486 
3487     G1STWIsAliveClosure is_alive(_g1h);
3488 
3489     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3490     pss->set_ref_discoverer(NULL);
3491 
3492     // Keep alive closure.
3493     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3494 
3495     // Complete GC closure
3496     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3497 
3498     // Call the reference processing task's work routine.
3499     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3500 
3501     // Note we cannot assert that the refs array is empty here as not all
3502     // of the processing tasks (specifically phase2 - pp2_work) execute
3503     // the complete_gc closure (which ordinarily would drain the queue) so
3504     // the queue may not be empty.
3505   }
3506 };
3507 
3508 // Driver routine for parallel reference processing.
3509 // Creates an instance of the ref processing gang
3510 // task and has the worker threads execute it.
3511 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3512   assert(_workers != NULL, "Need parallel worker threads.");
3513 
3514   assert(_workers->active_workers() >= ergo_workers,
3515          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3516          ergo_workers, _workers->active_workers());
3517   TaskTerminator terminator(ergo_workers, _queues);
3518   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3519 
3520   _workers->run_task(&proc_task_proxy, ergo_workers);
3521 }
3522 
3523 // End of weak reference support closures
3524 
3525 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3526   double ref_proc_start = os::elapsedTime();
3527 
3528   ReferenceProcessor* rp = _ref_processor_stw;
3529   assert(rp->discovery_enabled(), "should have been enabled");
3530 
3531   // Closure to test whether a referent is alive.
3532   G1STWIsAliveClosure is_alive(this);
3533 
3534   // Even when parallel reference processing is enabled, the processing
3535   // of JNI refs is serial and performed serially by the current thread
3536   // rather than by a worker. The following PSS will be used for processing
3537   // JNI refs.
3538 
3539   // Use only a single queue for this PSS.
3540   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3541   pss->set_ref_discoverer(NULL);
3542   assert(pss->queue_is_empty(), "pre-condition");
3543 
3544   // Keep alive closure.
3545   G1CopyingKeepAliveClosure keep_alive(this, pss);
3546 
3547   // Serial Complete GC closure
3548   G1STWDrainQueueClosure drain_queue(this, pss);
3549 
3550   // Setup the soft refs policy...
3551   rp->setup_policy(false);
3552 
3553   ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3554 
3555   ReferenceProcessorStats stats;
3556   if (!rp->processing_is_mt()) {
3557     // Serial reference processing...
3558     stats = rp->process_discovered_references(&is_alive,
3559                                               &keep_alive,
3560                                               &drain_queue,
3561                                               NULL,
3562                                               pt);
3563   } else {
3564     uint no_of_gc_workers = workers()->active_workers();
3565 
3566     // Parallel reference processing
3567     assert(no_of_gc_workers <= rp->max_num_queues(),
3568            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3569            no_of_gc_workers,  rp->max_num_queues());
3570 
3571     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3572     stats = rp->process_discovered_references(&is_alive,
3573                                               &keep_alive,
3574                                               &drain_queue,
3575                                               &par_task_executor,
3576                                               pt);
3577   }
3578 
3579   _gc_tracer_stw->report_gc_reference_stats(stats);
3580 
3581   // We have completed copying any necessary live referent objects.
3582   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3583 
3584   make_pending_list_reachable();
3585 
3586   assert(!rp->discovery_enabled(), "Postcondition");
3587   rp->verify_no_references_recorded();
3588 
3589   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3590   phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3591 }
3592 
3593 void G1CollectedHeap::make_pending_list_reachable() {
3594   if (collector_state()->in_initial_mark_gc()) {
3595     oop pll_head = Universe::reference_pending_list();
3596     if (pll_head != NULL) {
3597       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3598       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3599     }
3600   }
3601 }
3602 
3603 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3604   Ticks start = Ticks::now();
3605   per_thread_states->flush();
3606   phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3607 }
3608 
3609 class G1PrepareEvacuationTask : public AbstractGangTask {
3610   class G1PrepareRegionsClosure : public HeapRegionClosure {
3611     G1CollectedHeap* _g1h;
3612     G1PrepareEvacuationTask* _parent_task;
3613     size_t _worker_humongous_total;
3614     size_t _worker_humongous_candidates;
3615 
3616     bool humongous_region_is_candidate(HeapRegion* region) const {
3617       assert(region->is_starts_humongous(), "Must start a humongous object");
3618 
3619       oop obj = oop(region->bottom());
3620 
3621       // Dead objects cannot be eager reclaim candidates. Due to class
3622       // unloading it is unsafe to query their classes so we return early.
3623       if (_g1h->is_obj_dead(obj, region)) {
3624         return false;
3625       }
3626 
3627       // If we do not have a complete remembered set for the region, then we can
3628       // not be sure that we have all references to it.
3629       if (!region->rem_set()->is_complete()) {
3630         return false;
3631       }
3632       // Candidate selection must satisfy the following constraints
3633       // while concurrent marking is in progress:
3634       //
3635       // * In order to maintain SATB invariants, an object must not be
3636       // reclaimed if it was allocated before the start of marking and
3637       // has not had its references scanned.  Such an object must have
3638       // its references (including type metadata) scanned to ensure no
3639       // live objects are missed by the marking process.  Objects
3640       // allocated after the start of concurrent marking don't need to
3641       // be scanned.
3642       //
3643       // * An object must not be reclaimed if it is on the concurrent
3644       // mark stack.  Objects allocated after the start of concurrent
3645       // marking are never pushed on the mark stack.
3646       //
3647       // Nominating only objects allocated after the start of concurrent
3648       // marking is sufficient to meet both constraints.  This may miss
3649       // some objects that satisfy the constraints, but the marking data
3650       // structures don't support efficiently performing the needed
3651       // additional tests or scrubbing of the mark stack.
3652       //
3653       // However, we presently only nominate is_typeArray() objects.
3654       // A humongous object containing references induces remembered
3655       // set entries on other regions.  In order to reclaim such an
3656       // object, those remembered sets would need to be cleaned up.
3657       //
3658       // We also treat is_typeArray() objects specially, allowing them
3659       // to be reclaimed even if allocated before the start of
3660       // concurrent mark.  For this we rely on mark stack insertion to
3661       // exclude is_typeArray() objects, preventing reclaiming an object
3662       // that is in the mark stack.  We also rely on the metadata for
3663       // such objects to be built-in and so ensured to be kept live.
3664       // Frequent allocation and drop of large binary blobs is an
3665       // important use case for eager reclaim, and this special handling
3666       // may reduce needed headroom.
3667 
3668       return obj->is_typeArray() &&
3669              _g1h->is_potential_eager_reclaim_candidate(region);
3670     }
3671 
3672   public:
3673     G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3674       _g1h(g1h),
3675       _parent_task(parent_task),
3676       _worker_humongous_total(0),
3677       _worker_humongous_candidates(0) { }
3678 
3679     ~G1PrepareRegionsClosure() {
3680       _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3681       _parent_task->add_humongous_total(_worker_humongous_total);
3682     }
3683 
3684     virtual bool do_heap_region(HeapRegion* hr) {
3685       // First prepare the region for scanning
3686       _g1h->rem_set()->prepare_region_for_scan(hr);
3687 
3688       // Now check if region is a humongous candidate
3689       if (!hr->is_starts_humongous()) {
3690         _g1h->register_region_with_region_attr(hr);
3691         return false;
3692       }
3693 
3694       uint index = hr->hrm_index();
3695       if (humongous_region_is_candidate(hr)) {
3696         _g1h->set_humongous_reclaim_candidate(index, true);
3697         _g1h->register_humongous_region_with_region_attr(index);
3698         _worker_humongous_candidates++;
3699         // We will later handle the remembered sets of these regions.
3700       } else {
3701         _g1h->set_humongous_reclaim_candidate(index, false);
3702         _g1h->register_region_with_region_attr(hr);
3703       }
3704       _worker_humongous_total++;
3705 
3706       return false;
3707     }
3708   };
3709 
3710   G1CollectedHeap* _g1h;
3711   HeapRegionClaimer _claimer;
3712   volatile size_t _humongous_total;
3713   volatile size_t _humongous_candidates;
3714 public:
3715   G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3716     AbstractGangTask("Prepare Evacuation"),
3717     _g1h(g1h),
3718     _claimer(_g1h->workers()->active_workers()),
3719     _humongous_total(0),
3720     _humongous_candidates(0) { }
3721 
3722   ~G1PrepareEvacuationTask() {
3723     _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3724   }
3725 
3726   void work(uint worker_id) {
3727     G1PrepareRegionsClosure cl(_g1h, this);
3728     _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3729   }
3730 
3731   void add_humongous_candidates(size_t candidates) {
3732     Atomic::add(&_humongous_candidates, candidates);
3733   }
3734 
3735   void add_humongous_total(size_t total) {
3736     Atomic::add(&_humongous_total, total);
3737   }
3738 
3739   size_t humongous_candidates() {
3740     return _humongous_candidates;
3741   }
3742 
3743   size_t humongous_total() {
3744     return _humongous_total;
3745   }
3746 };
3747 
3748 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3749   _bytes_used_during_gc = 0;
3750 
3751   _expand_heap_after_alloc_failure = true;
3752   _evacuation_failed = false;
3753 
3754   // Disable the hot card cache.
3755   _hot_card_cache->reset_hot_cache_claimed_index();
3756   _hot_card_cache->set_use_cache(false);
3757 
3758   // Initialize the GC alloc regions.
3759   _allocator->init_gc_alloc_regions(evacuation_info);
3760 
3761   {
3762     Ticks start = Ticks::now();
3763     rem_set()->prepare_for_scan_heap_roots();
3764     phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3765   }
3766 
3767   {
3768     G1PrepareEvacuationTask g1_prep_task(this);
3769     Tickspan task_time = run_task(&g1_prep_task);
3770 
3771     phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3772                                            g1_prep_task.humongous_total(),
3773                                            g1_prep_task.humongous_candidates());
3774   }
3775 
3776   assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3777   _preserved_marks_set.assert_empty();
3778 
3779 #if COMPILER2_OR_JVMCI
3780   DerivedPointerTable::clear();
3781 #endif
3782 
3783   // InitialMark needs claim bits to keep track of the marked-through CLDs.
3784   if (collector_state()->in_initial_mark_gc()) {
3785     concurrent_mark()->pre_initial_mark();
3786 
3787     double start_clear_claimed_marks = os::elapsedTime();
3788 
3789     ClassLoaderDataGraph::clear_claimed_marks();
3790 
3791     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3792     phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3793   }
3794 
3795   // Should G1EvacuationFailureALot be in effect for this GC?
3796   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3797 }
3798 
3799 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3800 protected:
3801   G1CollectedHeap* _g1h;
3802   G1ParScanThreadStateSet* _per_thread_states;
3803   RefToScanQueueSet* _task_queues;
3804   TaskTerminator _terminator;
3805   uint _num_workers;
3806 
3807   void evacuate_live_objects(G1ParScanThreadState* pss,
3808                              uint worker_id,
3809                              G1GCPhaseTimes::GCParPhases objcopy_phase,
3810                              G1GCPhaseTimes::GCParPhases termination_phase) {
3811     G1GCPhaseTimes* p = _g1h->phase_times();
3812 
3813     Ticks start = Ticks::now();
3814     G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3815     cl.do_void();
3816 
3817     assert(pss->queue_is_empty(), "should be empty");
3818 
3819     Tickspan evac_time = (Ticks::now() - start);
3820     p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3821 
3822     if (termination_phase == G1GCPhaseTimes::Termination) {
3823       p->record_time_secs(termination_phase, worker_id, cl.term_time());
3824       p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3825     } else {
3826       p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3827       p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3828     }
3829     assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3830   }
3831 
3832   virtual void start_work(uint worker_id) { }
3833 
3834   virtual void end_work(uint worker_id) { }
3835 
3836   virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3837 
3838   virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3839 
3840 public:
3841   G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3842     AbstractGangTask(name),
3843     _g1h(G1CollectedHeap::heap()),
3844     _per_thread_states(per_thread_states),
3845     _task_queues(task_queues),
3846     _terminator(num_workers, _task_queues),
3847     _num_workers(num_workers)
3848   { }
3849 
3850   void work(uint worker_id) {
3851     start_work(worker_id);
3852 
3853     {
3854       ResourceMark rm;
3855       HandleMark   hm;
3856 
3857       G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3858       pss->set_ref_discoverer(_g1h->ref_processor_stw());
3859 
3860       scan_roots(pss, worker_id);
3861       evacuate_live_objects(pss, worker_id);
3862     }
3863 
3864     end_work(worker_id);
3865   }
3866 };
3867 
3868 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3869   G1RootProcessor* _root_processor;
3870 
3871   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3872     _root_processor->evacuate_roots(pss, worker_id);
3873     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3874     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3875   }
3876 
3877   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3878     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3879   }
3880 
3881   void start_work(uint worker_id) {
3882     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3883   }
3884 
3885   void end_work(uint worker_id) {
3886     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3887   }
3888 
3889 public:
3890   G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3891                         G1ParScanThreadStateSet* per_thread_states,
3892                         RefToScanQueueSet* task_queues,
3893                         G1RootProcessor* root_processor,
3894                         uint num_workers) :
3895     G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3896     _root_processor(root_processor)
3897   { }
3898 };
3899 
3900 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3901   G1GCPhaseTimes* p = phase_times();
3902 
3903   {
3904     Ticks start = Ticks::now();
3905     rem_set()->merge_heap_roots(true /* initial_evacuation */);
3906     p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3907   }
3908 
3909   Tickspan task_time;
3910   const uint num_workers = workers()->active_workers();
3911 
3912   Ticks start_processing = Ticks::now();
3913   {
3914     G1RootProcessor root_processor(this, num_workers);
3915     G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3916     task_time = run_task(&g1_par_task);
3917     // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3918     // To extract its code root fixup time we measure total time of this scope and
3919     // subtract from the time the WorkGang task took.
3920   }
3921   Tickspan total_processing = Ticks::now() - start_processing;
3922 
3923   p->record_initial_evac_time(task_time.seconds() * 1000.0);
3924   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3925 }
3926 
3927 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3928 
3929   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3930     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3931     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3932   }
3933 
3934   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3935     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3936   }
3937 
3938 public:
3939   G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3940                                 RefToScanQueueSet* queues,
3941                                 uint num_workers) :
3942     G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3943   }
3944 };
3945 
3946 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3947   class G1MarkScope : public MarkScope { };
3948 
3949   Tickspan task_time;
3950 
3951   Ticks start_processing = Ticks::now();
3952   {
3953     G1MarkScope code_mark_scope;
3954     G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3955     task_time = run_task(&task);
3956     // See comment in evacuate_collection_set() for the reason of the scope.
3957   }
3958   Tickspan total_processing = Ticks::now() - start_processing;
3959 
3960   G1GCPhaseTimes* p = phase_times();
3961   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3962 }
3963 
3964 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3965   const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3966 
3967   while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3968 
3969     double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3970     double time_left_ms = MaxGCPauseMillis - time_used_ms;
3971 
3972     if (time_left_ms < 0 ||
3973         !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3974       log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3975                                 _collection_set.optional_region_length(), time_left_ms);
3976       break;
3977     }
3978 
3979     {
3980       Ticks start = Ticks::now();
3981       rem_set()->merge_heap_roots(false /* initial_evacuation */);
3982       phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3983     }
3984 
3985     {
3986       Ticks start = Ticks::now();
3987       evacuate_next_optional_regions(per_thread_states);
3988       phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3989     }
3990   }
3991 
3992   _collection_set.abandon_optional_collection_set(per_thread_states);
3993 }
3994 
3995 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3996                                                    G1RedirtyCardsQueueSet* rdcqs,
3997                                                    G1ParScanThreadStateSet* per_thread_states) {
3998   G1GCPhaseTimes* p = phase_times();
3999 
4000   rem_set()->cleanup_after_scan_heap_roots();
4001 
4002   // Process any discovered reference objects - we have
4003   // to do this _before_ we retire the GC alloc regions
4004   // as we may have to copy some 'reachable' referent
4005   // objects (and their reachable sub-graphs) that were
4006   // not copied during the pause.
4007   process_discovered_references(per_thread_states);
4008 
4009   G1STWIsAliveClosure is_alive(this);
4010   G1KeepAliveClosure keep_alive(this);
4011 
4012   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
4013 
4014   if (G1StringDedup::is_enabled()) {
4015     double string_dedup_time_ms = os::elapsedTime();
4016 
4017     string_dedup_cleaning(&is_alive, &keep_alive, p);
4018 
4019     double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
4020     p->record_string_deduplication_time(string_cleanup_time_ms);
4021   }
4022 
4023   _allocator->release_gc_alloc_regions(evacuation_info);
4024 
4025   if (evacuation_failed()) {
4026     restore_after_evac_failure(rdcqs);
4027 
4028     // Reset the G1EvacuationFailureALot counters and flags
4029     NOT_PRODUCT(reset_evacuation_should_fail();)
4030 
4031     double recalculate_used_start = os::elapsedTime();
4032     set_used(recalculate_used());
4033     p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
4034 
4035     if (_archive_allocator != NULL) {
4036       _archive_allocator->clear_used();
4037     }
4038     for (uint i = 0; i < ParallelGCThreads; i++) {
4039       if (_evacuation_failed_info_array[i].has_failed()) {
4040         _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4041       }
4042     }
4043   } else {
4044     // The "used" of the the collection set have already been subtracted
4045     // when they were freed.  Add in the bytes used.
4046     increase_used(_bytes_used_during_gc);
4047   }
4048 
4049   _preserved_marks_set.assert_empty();
4050 
4051   merge_per_thread_state_info(per_thread_states);
4052 
4053   // Reset and re-enable the hot card cache.
4054   // Note the counts for the cards in the regions in the
4055   // collection set are reset when the collection set is freed.
4056   _hot_card_cache->reset_hot_cache();
4057   _hot_card_cache->set_use_cache(true);
4058 
4059   purge_code_root_memory();
4060 
4061   redirty_logged_cards(rdcqs);
4062 
4063   free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4064 
4065   eagerly_reclaim_humongous_regions();
4066 
4067   record_obj_copy_mem_stats();
4068 
4069   evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4070   evacuation_info.set_bytes_used(_bytes_used_during_gc);
4071 
4072 #if COMPILER2_OR_JVMCI
4073   double start = os::elapsedTime();
4074   DerivedPointerTable::update_pointers();
4075   phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4076 #endif
4077   policy()->print_age_table();
4078 }
4079 
4080 void G1CollectedHeap::record_obj_copy_mem_stats() {
4081   policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4082 
4083   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4084                                                create_g1_evac_summary(&_old_evac_stats));
4085 }
4086 
4087 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4088   assert(!hr->is_free(), "the region should not be free");
4089   assert(!hr->is_empty(), "the region should not be empty");
4090   assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4091 
4092   if (G1VerifyBitmaps) {
4093     MemRegion mr(hr->bottom(), hr->end());
4094     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4095   }
4096 
4097   // Clear the card counts for this region.
4098   // Note: we only need to do this if the region is not young
4099   // (since we don't refine cards in young regions).
4100   if (!hr->is_young()) {
4101     _hot_card_cache->reset_card_counts(hr);
4102   }
4103 
4104   // Reset region metadata to allow reuse.
4105   hr->hr_clear(true /* clear_space */);
4106   _policy->remset_tracker()->update_at_free(hr);
4107 
4108   if (free_list != NULL) {
4109     free_list->add_ordered(hr);
4110   }
4111 }
4112 
4113 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4114                                             FreeRegionList* free_list) {
4115   assert(hr->is_humongous(), "this is only for humongous regions");
4116   assert(free_list != NULL, "pre-condition");
4117   hr->clear_humongous();
4118   free_region(hr, free_list);
4119 }
4120 
4121 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4122                                            const uint humongous_regions_removed) {
4123   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4124     MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4125     _old_set.bulk_remove(old_regions_removed);
4126     _humongous_set.bulk_remove(humongous_regions_removed);
4127   }
4128 
4129 }
4130 
4131 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4132   assert(list != NULL, "list can't be null");
4133   if (!list->is_empty()) {
4134     MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4135     _hrm->insert_list_into_free_list(list);
4136   }
4137 }
4138 
4139 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4140   decrease_used(bytes);
4141 }
4142 
4143 class G1FreeCollectionSetTask : public AbstractGangTask {
4144   // Helper class to keep statistics for the collection set freeing
4145   class FreeCSetStats {
4146     size_t _before_used_bytes;   // Usage in regions successfully evacutate
4147     size_t _after_used_bytes;    // Usage in regions failing evacuation
4148     size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4149     size_t _failure_used_words;  // Live size in failed regions
4150     size_t _failure_waste_words; // Wasted size in failed regions
4151     size_t _rs_length;           // Remembered set size
4152     uint _regions_freed;         // Number of regions freed
4153   public:
4154     FreeCSetStats() :
4155         _before_used_bytes(0),
4156         _after_used_bytes(0),
4157         _bytes_allocated_in_old_since_last_gc(0),
4158         _failure_used_words(0),
4159         _failure_waste_words(0),
4160         _rs_length(0),
4161         _regions_freed(0) { }
4162 
4163     void merge_stats(FreeCSetStats* other) {
4164       assert(other != NULL, "invariant");
4165       _before_used_bytes += other->_before_used_bytes;
4166       _after_used_bytes += other->_after_used_bytes;
4167       _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4168       _failure_used_words += other->_failure_used_words;
4169       _failure_waste_words += other->_failure_waste_words;
4170       _rs_length += other->_rs_length;
4171       _regions_freed += other->_regions_freed;
4172     }
4173 
4174     void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4175       evacuation_info->set_regions_freed(_regions_freed);
4176       evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4177 
4178       g1h->decrement_summary_bytes(_before_used_bytes);
4179       g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4180 
4181       G1Policy *policy = g1h->policy();
4182       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4183       policy->record_rs_length(_rs_length);
4184       policy->cset_regions_freed();
4185     }
4186 
4187     void account_failed_region(HeapRegion* r) {
4188       size_t used_words = r->marked_bytes() / HeapWordSize;
4189       _failure_used_words += used_words;
4190       _failure_waste_words += HeapRegion::GrainWords - used_words;
4191       _after_used_bytes += r->used();
4192 
4193       // When moving a young gen region to old gen, we "allocate" that whole
4194       // region there. This is in addition to any already evacuated objects.
4195       // Notify the policy about that. Old gen regions do not cause an
4196       // additional allocation: both the objects still in the region and the
4197       // ones already moved are accounted for elsewhere.
4198       if (r->is_young()) {
4199         _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4200       }
4201     }
4202 
4203     void account_evacuated_region(HeapRegion* r) {
4204       _before_used_bytes += r->used();
4205       _regions_freed += 1;
4206     }
4207 
4208     void account_rs_length(HeapRegion* r) {
4209       _rs_length += r->rem_set()->occupied();
4210     }
4211   };
4212 
4213   // Closure applied to all regions in the collection set.
4214   class FreeCSetClosure : public HeapRegionClosure {
4215     // Helper to send JFR events for regions.
4216     class JFREventForRegion {
4217       EventGCPhaseParallel _event;
4218     public:
4219       JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4220         _event.set_gcId(GCId::current());
4221         _event.set_gcWorkerId(worker_id);
4222         if (region->is_young()) {
4223           _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4224         } else {
4225           _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4226         }
4227       }
4228 
4229       ~JFREventForRegion() {
4230         _event.commit();
4231       }
4232     };
4233 
4234     // Helper to do timing for region work.
4235     class TimerForRegion {
4236       Tickspan& _time;
4237       Ticks     _start_time;
4238     public:
4239       TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4240       ~TimerForRegion() {
4241         _time += Ticks::now() - _start_time;
4242       }
4243     };
4244 
4245     // FreeCSetClosure members
4246     G1CollectedHeap* _g1h;
4247     const size_t*    _surviving_young_words;
4248     uint             _worker_id;
4249     Tickspan         _young_time;
4250     Tickspan         _non_young_time;
4251     FreeCSetStats*   _stats;
4252 
4253     void assert_in_cset(HeapRegion* r) {
4254       assert(r->young_index_in_cset() != 0 &&
4255              (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4256              "Young index %u is wrong for region %u of type %s with %u young regions",
4257              r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4258     }
4259 
4260     void handle_evacuated_region(HeapRegion* r) {
4261       assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4262       stats()->account_evacuated_region(r);
4263 
4264       // Free the region and and its remembered set.
4265       _g1h->free_region(r, NULL);
4266     }
4267 
4268     void handle_failed_region(HeapRegion* r) {
4269       // Do some allocation statistics accounting. Regions that failed evacuation
4270       // are always made old, so there is no need to update anything in the young
4271       // gen statistics, but we need to update old gen statistics.
4272       stats()->account_failed_region(r);
4273 
4274       // Update the region state due to the failed evacuation.
4275       r->handle_evacuation_failure();
4276 
4277       // Add region to old set, need to hold lock.
4278       MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4279       _g1h->old_set_add(r);
4280     }
4281 
4282     Tickspan& timer_for_region(HeapRegion* r) {
4283       return r->is_young() ? _young_time : _non_young_time;
4284     }
4285 
4286     FreeCSetStats* stats() {
4287       return _stats;
4288     }
4289   public:
4290     FreeCSetClosure(const size_t* surviving_young_words,
4291                     uint worker_id,
4292                     FreeCSetStats* stats) :
4293         HeapRegionClosure(),
4294         _g1h(G1CollectedHeap::heap()),
4295         _surviving_young_words(surviving_young_words),
4296         _worker_id(worker_id),
4297         _young_time(),
4298         _non_young_time(),
4299         _stats(stats) { }
4300 
4301     virtual bool do_heap_region(HeapRegion* r) {
4302       assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4303       JFREventForRegion event(r, _worker_id);
4304       TimerForRegion timer(timer_for_region(r));
4305 
4306       _g1h->clear_region_attr(r);
4307       stats()->account_rs_length(r);
4308 
4309       if (r->is_young()) {
4310         assert_in_cset(r);
4311         r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4312       }
4313 
4314       if (r->evacuation_failed()) {
4315         handle_failed_region(r);
4316       } else {
4317         handle_evacuated_region(r);
4318       }
4319       assert(!_g1h->is_on_master_free_list(r), "sanity");
4320 
4321       return false;
4322     }
4323 
4324     void report_timing(Tickspan parallel_time) {
4325       G1GCPhaseTimes* pt = _g1h->phase_times();
4326       pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4327       if (_young_time.value() > 0) {
4328         pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4329       }
4330       if (_non_young_time.value() > 0) {
4331         pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4332       }
4333     }
4334   };
4335 
4336   // G1FreeCollectionSetTask members
4337   G1CollectedHeap*  _g1h;
4338   G1EvacuationInfo* _evacuation_info;
4339   FreeCSetStats*    _worker_stats;
4340   HeapRegionClaimer _claimer;
4341   const size_t*     _surviving_young_words;
4342   uint              _active_workers;
4343 
4344   FreeCSetStats* worker_stats(uint worker) {
4345     return &_worker_stats[worker];
4346   }
4347 
4348   void report_statistics() {
4349     // Merge the accounting
4350     FreeCSetStats total_stats;
4351     for (uint worker = 0; worker < _active_workers; worker++) {
4352       total_stats.merge_stats(worker_stats(worker));
4353     }
4354     total_stats.report(_g1h, _evacuation_info);
4355   }
4356 
4357 public:
4358   G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4359       AbstractGangTask("G1 Free Collection Set"),
4360       _g1h(G1CollectedHeap::heap()),
4361       _evacuation_info(evacuation_info),
4362       _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4363       _claimer(active_workers),
4364       _surviving_young_words(surviving_young_words),
4365       _active_workers(active_workers) {
4366     for (uint worker = 0; worker < active_workers; worker++) {
4367       ::new (&_worker_stats[worker]) FreeCSetStats();
4368     }
4369   }
4370 
4371   ~G1FreeCollectionSetTask() {
4372     Ticks serial_time = Ticks::now();
4373     report_statistics();
4374     for (uint worker = 0; worker < _active_workers; worker++) {
4375       _worker_stats[worker].~FreeCSetStats();
4376     }
4377     FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4378     _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4379   }
4380 
4381   virtual void work(uint worker_id) {
4382     EventGCPhaseParallel event;
4383     Ticks start = Ticks::now();
4384     FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4385     _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4386 
4387     // Report the total parallel time along with some more detailed metrics.
4388     cl.report_timing(Ticks::now() - start);
4389     event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4390   }
4391 };
4392 
4393 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4394   _eden.clear();
4395 
4396   // The free collections set is split up in two tasks, the first
4397   // frees the collection set and records what regions are free,
4398   // and the second one rebuilds the free list. This proved to be
4399   // more efficient than adding a sorted list to another.
4400 
4401   Ticks free_cset_start_time = Ticks::now();
4402   {
4403     uint const num_cs_regions = _collection_set.region_length();
4404     uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4405     G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4406 
4407     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4408                         cl.name(), num_workers, num_cs_regions, num_regions());
4409     workers()->run_task(&cl, num_workers);
4410   }
4411 
4412   Ticks free_cset_end_time = Ticks::now();
4413   phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4414 
4415   // Now rebuild the free region list.
4416   hrm()->rebuild_free_list(workers());
4417   phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4418 
4419   collection_set->clear();
4420 }
4421 
4422 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4423  private:
4424   FreeRegionList* _free_region_list;
4425   HeapRegionSet* _proxy_set;
4426   uint _humongous_objects_reclaimed;
4427   uint _humongous_regions_reclaimed;
4428   size_t _freed_bytes;
4429  public:
4430 
4431   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4432     _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4433   }
4434 
4435   virtual bool do_heap_region(HeapRegion* r) {
4436     if (!r->is_starts_humongous()) {
4437       return false;
4438     }
4439 
4440     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4441 
4442     oop obj = (oop)r->bottom();
4443     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4444 
4445     // The following checks whether the humongous object is live are sufficient.
4446     // The main additional check (in addition to having a reference from the roots
4447     // or the young gen) is whether the humongous object has a remembered set entry.
4448     //
4449     // A humongous object cannot be live if there is no remembered set for it
4450     // because:
4451     // - there can be no references from within humongous starts regions referencing
4452     // the object because we never allocate other objects into them.
4453     // (I.e. there are no intra-region references that may be missed by the
4454     // remembered set)
4455     // - as soon there is a remembered set entry to the humongous starts region
4456     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4457     // until the end of a concurrent mark.
4458     //
4459     // It is not required to check whether the object has been found dead by marking
4460     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4461     // all objects allocated during that time are considered live.
4462     // SATB marking is even more conservative than the remembered set.
4463     // So if at this point in the collection there is no remembered set entry,
4464     // nobody has a reference to it.
4465     // At the start of collection we flush all refinement logs, and remembered sets
4466     // are completely up-to-date wrt to references to the humongous object.
4467     //
4468     // Other implementation considerations:
4469     // - never consider object arrays at this time because they would pose
4470     // considerable effort for cleaning up the the remembered sets. This is
4471     // required because stale remembered sets might reference locations that
4472     // are currently allocated into.
4473     uint region_idx = r->hrm_index();
4474     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4475         !r->rem_set()->is_empty()) {
4476       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",
4477                                region_idx,
4478                                (size_t)obj->size() * HeapWordSize,
4479                                p2i(r->bottom()),
4480                                r->rem_set()->occupied(),
4481                                r->rem_set()->strong_code_roots_list_length(),
4482                                next_bitmap->is_marked(r->bottom()),
4483                                g1h->is_humongous_reclaim_candidate(region_idx),
4484                                obj->is_typeArray()
4485                               );
4486       return false;
4487     }
4488 
4489     guarantee(obj->is_typeArray(),
4490               "Only eagerly reclaiming type arrays is supported, but the object "
4491               PTR_FORMAT " is not.", p2i(r->bottom()));
4492 
4493     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",
4494                              region_idx,
4495                              (size_t)obj->size() * HeapWordSize,
4496                              p2i(r->bottom()),
4497                              r->rem_set()->occupied(),
4498                              r->rem_set()->strong_code_roots_list_length(),
4499                              next_bitmap->is_marked(r->bottom()),
4500                              g1h->is_humongous_reclaim_candidate(region_idx),
4501                              obj->is_typeArray()
4502                             );
4503 
4504     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4505     cm->humongous_object_eagerly_reclaimed(r);
4506     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4507            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4508            region_idx,
4509            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4510            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4511     _humongous_objects_reclaimed++;
4512     do {
4513       HeapRegion* next = g1h->next_region_in_humongous(r);
4514       _freed_bytes += r->used();
4515       r->set_containing_set(NULL);
4516       _humongous_regions_reclaimed++;
4517       g1h->free_humongous_region(r, _free_region_list);
4518       r = next;
4519     } while (r != NULL);
4520 
4521     return false;
4522   }
4523 
4524   uint humongous_objects_reclaimed() {
4525     return _humongous_objects_reclaimed;
4526   }
4527 
4528   uint humongous_regions_reclaimed() {
4529     return _humongous_regions_reclaimed;
4530   }
4531 
4532   size_t bytes_freed() const {
4533     return _freed_bytes;
4534   }
4535 };
4536 
4537 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4538   assert_at_safepoint_on_vm_thread();
4539 
4540   if (!G1EagerReclaimHumongousObjects ||
4541       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4542     phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4543     return;
4544   }
4545 
4546   double start_time = os::elapsedTime();
4547 
4548   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4549 
4550   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4551   heap_region_iterate(&cl);
4552 
4553   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4554 
4555   G1HRPrinter* hrp = hr_printer();
4556   if (hrp->is_active()) {
4557     FreeRegionListIterator iter(&local_cleanup_list);
4558     while (iter.more_available()) {
4559       HeapRegion* hr = iter.get_next();
4560       hrp->cleanup(hr);
4561     }
4562   }
4563 
4564   prepend_to_freelist(&local_cleanup_list);
4565   decrement_summary_bytes(cl.bytes_freed());
4566 
4567   phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4568                                                        cl.humongous_objects_reclaimed());
4569 }
4570 
4571 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4572 public:
4573   virtual bool do_heap_region(HeapRegion* r) {
4574     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4575     G1CollectedHeap::heap()->clear_region_attr(r);
4576     r->clear_young_index_in_cset();
4577     return false;
4578   }
4579 };
4580 
4581 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4582   G1AbandonCollectionSetClosure cl;
4583   collection_set_iterate_all(&cl);
4584 
4585   collection_set->clear();
4586   collection_set->stop_incremental_building();
4587 }
4588 
4589 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4590   return _allocator->is_retained_old_region(hr);
4591 }
4592 
4593 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4594   _eden.add(hr);
4595   _policy->set_region_eden(hr);
4596 }
4597 
4598 #ifdef ASSERT
4599 
4600 class NoYoungRegionsClosure: public HeapRegionClosure {
4601 private:
4602   bool _success;
4603 public:
4604   NoYoungRegionsClosure() : _success(true) { }
4605   bool do_heap_region(HeapRegion* r) {
4606     if (r->is_young()) {
4607       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4608                             p2i(r->bottom()), p2i(r->end()));
4609       _success = false;
4610     }
4611     return false;
4612   }
4613   bool success() { return _success; }
4614 };
4615 
4616 bool G1CollectedHeap::check_young_list_empty() {
4617   bool ret = (young_regions_count() == 0);
4618 
4619   NoYoungRegionsClosure closure;
4620   heap_region_iterate(&closure);
4621   ret = ret && closure.success();
4622 
4623   return ret;
4624 }
4625 
4626 #endif // ASSERT
4627 
4628 class TearDownRegionSetsClosure : public HeapRegionClosure {
4629   HeapRegionSet *_old_set;
4630 
4631 public:
4632   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4633 
4634   bool do_heap_region(HeapRegion* r) {
4635     if (r->is_old()) {
4636       _old_set->remove(r);
4637     } else if(r->is_young()) {
4638       r->uninstall_surv_rate_group();
4639     } else {
4640       // We ignore free regions, we'll empty the free list afterwards.
4641       // We ignore humongous and archive regions, we're not tearing down these
4642       // sets.
4643       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4644              "it cannot be another type");
4645     }
4646     return false;
4647   }
4648 
4649   ~TearDownRegionSetsClosure() {
4650     assert(_old_set->is_empty(), "post-condition");
4651   }
4652 };
4653 
4654 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4655   assert_at_safepoint_on_vm_thread();
4656 
4657   if (!free_list_only) {
4658     TearDownRegionSetsClosure cl(&_old_set);
4659     heap_region_iterate(&cl);
4660 
4661     // Note that emptying the _young_list is postponed and instead done as
4662     // the first step when rebuilding the regions sets again. The reason for
4663     // this is that during a full GC string deduplication needs to know if
4664     // a collected region was young or old when the full GC was initiated.
4665   }
4666   _hrm->remove_all_free_regions();
4667 }
4668 
4669 void G1CollectedHeap::increase_used(size_t bytes) {
4670   _summary_bytes_used += bytes;
4671 }
4672 
4673 void G1CollectedHeap::decrease_used(size_t bytes) {
4674   assert(_summary_bytes_used >= bytes,
4675          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4676          _summary_bytes_used, bytes);
4677   _summary_bytes_used -= bytes;
4678 }
4679 
4680 void G1CollectedHeap::set_used(size_t bytes) {
4681   _summary_bytes_used = bytes;
4682 }
4683 
4684 class RebuildRegionSetsClosure : public HeapRegionClosure {
4685 private:
4686   bool _free_list_only;
4687 
4688   HeapRegionSet* _old_set;
4689   HeapRegionManager* _hrm;
4690 
4691   size_t _total_used;
4692 
4693 public:
4694   RebuildRegionSetsClosure(bool free_list_only,
4695                            HeapRegionSet* old_set,
4696                            HeapRegionManager* hrm) :
4697     _free_list_only(free_list_only),
4698     _old_set(old_set), _hrm(hrm), _total_used(0) {
4699     assert(_hrm->num_free_regions() == 0, "pre-condition");
4700     if (!free_list_only) {
4701       assert(_old_set->is_empty(), "pre-condition");
4702     }
4703   }
4704 
4705   bool do_heap_region(HeapRegion* r) {
4706     if (r->is_empty()) {
4707       assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4708       // Add free regions to the free list
4709       r->set_free();
4710       _hrm->insert_into_free_list(r);
4711     } else if (!_free_list_only) {
4712       assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4713 
4714       if (r->is_archive() || r->is_humongous()) {
4715         // We ignore archive and humongous regions. We left these sets unchanged.
4716       } else {
4717         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4718         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4719         r->move_to_old();
4720         _old_set->add(r);
4721       }
4722       _total_used += r->used();
4723     }
4724 
4725     return false;
4726   }
4727 
4728   size_t total_used() {
4729     return _total_used;
4730   }
4731 };
4732 
4733 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4734   assert_at_safepoint_on_vm_thread();
4735 
4736   if (!free_list_only) {
4737     _eden.clear();
4738     _survivor.clear();
4739   }
4740 
4741   RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4742   heap_region_iterate(&cl);
4743 
4744   if (!free_list_only) {
4745     set_used(cl.total_used());
4746     if (_archive_allocator != NULL) {
4747       _archive_allocator->clear_used();
4748     }
4749   }
4750   assert_used_and_recalculate_used_equal(this);
4751 }
4752 
4753 // Methods for the mutator alloc region
4754 
4755 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4756                                                       bool force,
4757                                                       uint node_index) {
4758   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4759   bool should_allocate = policy()->should_allocate_mutator_region();
4760   if (force || should_allocate) {
4761     HeapRegion* new_alloc_region = new_region(word_size,
4762                                               HeapRegionType::Eden,
4763                                               false /* do_expand */,
4764                                               node_index);
4765     if (new_alloc_region != NULL) {
4766       set_region_short_lived_locked(new_alloc_region);
4767       _hr_printer.alloc(new_alloc_region, !should_allocate);
4768       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4769       _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4770       return new_alloc_region;
4771     }
4772   }
4773   return NULL;
4774 }
4775 
4776 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4777                                                   size_t allocated_bytes) {
4778   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4779   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4780 
4781   collection_set()->add_eden_region(alloc_region);
4782   increase_used(allocated_bytes);
4783   _eden.add_used_bytes(allocated_bytes);
4784   _hr_printer.retire(alloc_region);
4785 
4786   // We update the eden sizes here, when the region is retired,
4787   // instead of when it's allocated, since this is the point that its
4788   // used space has been recorded in _summary_bytes_used.
4789   g1mm()->update_eden_size();
4790 }
4791 
4792 // Methods for the GC alloc regions
4793 
4794 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4795   if (dest.is_old()) {
4796     return true;
4797   } else {
4798     return survivor_regions_count() < policy()->max_survivor_regions();
4799   }
4800 }
4801 
4802 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4803   assert(FreeList_lock->owned_by_self(), "pre-condition");
4804 
4805   if (!has_more_regions(dest)) {
4806     return NULL;
4807   }
4808 
4809   HeapRegionType type;
4810   if (dest.is_young()) {
4811     type = HeapRegionType::Survivor;
4812   } else {
4813     type = HeapRegionType::Old;
4814   }
4815 
4816   HeapRegion* new_alloc_region = new_region(word_size,
4817                                             type,
4818                                             true /* do_expand */,
4819                                             node_index);
4820 
4821   if (new_alloc_region != NULL) {
4822     if (type.is_survivor()) {
4823       new_alloc_region->set_survivor();
4824       _survivor.add(new_alloc_region);
4825       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4826     } else {
4827       new_alloc_region->set_old();
4828       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4829     }
4830     _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4831     register_region_with_region_attr(new_alloc_region);
4832     _hr_printer.alloc(new_alloc_region);
4833     return new_alloc_region;
4834   }
4835   return NULL;
4836 }
4837 
4838 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4839                                              size_t allocated_bytes,
4840                                              G1HeapRegionAttr dest) {
4841   _bytes_used_during_gc += allocated_bytes;
4842   if (dest.is_old()) {
4843     old_set_add(alloc_region);
4844   } else {
4845     assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4846     _survivor.add_used_bytes(allocated_bytes);
4847   }
4848 
4849   bool const during_im = collector_state()->in_initial_mark_gc();
4850   if (during_im && allocated_bytes > 0) {
4851     _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4852   }
4853   _hr_printer.retire(alloc_region);
4854 }
4855 
4856 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4857   bool expanded = false;
4858   uint index = _hrm->find_highest_free(&expanded);
4859 
4860   if (index != G1_NO_HRM_INDEX) {
4861     if (expanded) {
4862       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4863                                 HeapRegion::GrainWords * HeapWordSize);
4864     }
4865     _hrm->allocate_free_regions_starting_at(index, 1);
4866     return region_at(index);
4867   }
4868   return NULL;
4869 }
4870 
4871 // Optimized nmethod scanning
4872 
4873 class RegisterNMethodOopClosure: public OopClosure {
4874   G1CollectedHeap* _g1h;
4875   nmethod* _nm;
4876 
4877   template <class T> void do_oop_work(T* p) {
4878     T heap_oop = RawAccess<>::oop_load(p);
4879     if (!CompressedOops::is_null(heap_oop)) {
4880       oop obj = CompressedOops::decode_not_null(heap_oop);
4881       HeapRegion* hr = _g1h->heap_region_containing(obj);
4882       assert(!hr->is_continues_humongous(),
4883              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4884              " starting at " HR_FORMAT,
4885              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4886 
4887       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4888       hr->add_strong_code_root_locked(_nm);
4889     }
4890   }
4891 
4892 public:
4893   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4894     _g1h(g1h), _nm(nm) {}
4895 
4896   void do_oop(oop* p)       { do_oop_work(p); }
4897   void do_oop(narrowOop* p) { do_oop_work(p); }
4898 };
4899 
4900 class UnregisterNMethodOopClosure: public OopClosure {
4901   G1CollectedHeap* _g1h;
4902   nmethod* _nm;
4903 
4904   template <class T> void do_oop_work(T* p) {
4905     T heap_oop = RawAccess<>::oop_load(p);
4906     if (!CompressedOops::is_null(heap_oop)) {
4907       oop obj = CompressedOops::decode_not_null(heap_oop);
4908       HeapRegion* hr = _g1h->heap_region_containing(obj);
4909       assert(!hr->is_continues_humongous(),
4910              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4911              " starting at " HR_FORMAT,
4912              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4913 
4914       hr->remove_strong_code_root(_nm);
4915     }
4916   }
4917 
4918 public:
4919   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4920     _g1h(g1h), _nm(nm) {}
4921 
4922   void do_oop(oop* p)       { do_oop_work(p); }
4923   void do_oop(narrowOop* p) { do_oop_work(p); }
4924 };
4925 
4926 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4927   guarantee(nm != NULL, "sanity");
4928   RegisterNMethodOopClosure reg_cl(this, nm);
4929   nm->oops_do(&reg_cl);
4930 }
4931 
4932 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4933   guarantee(nm != NULL, "sanity");
4934   UnregisterNMethodOopClosure reg_cl(this, nm);
4935   nm->oops_do(&reg_cl, true);
4936 }
4937 
4938 void G1CollectedHeap::purge_code_root_memory() {
4939   double purge_start = os::elapsedTime();
4940   G1CodeRootSet::purge();
4941   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4942   phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4943 }
4944 
4945 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4946   G1CollectedHeap* _g1h;
4947 
4948 public:
4949   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4950     _g1h(g1h) {}
4951 
4952   void do_code_blob(CodeBlob* cb) {
4953     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4954     if (nm == NULL) {
4955       return;
4956     }
4957 
4958     _g1h->register_nmethod(nm);
4959   }
4960 };
4961 
4962 void G1CollectedHeap::rebuild_strong_code_roots() {
4963   RebuildStrongCodeRootClosure blob_cl(this);
4964   CodeCache::blobs_do(&blob_cl);
4965 }
4966 
4967 void G1CollectedHeap::initialize_serviceability() {
4968   _g1mm->initialize_serviceability();
4969 }
4970 
4971 MemoryUsage G1CollectedHeap::memory_usage() {
4972   return _g1mm->memory_usage();
4973 }
4974 
4975 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4976   return _g1mm->memory_managers();
4977 }
4978 
4979 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4980   return _g1mm->memory_pools();
4981 }
--- EOF ---