rev 58017 : [mq]: 8238854-remove-superfluous-alloc-checks

   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/taskTerminator.hpp"
  83 #include "gc/shared/taskqueue.inline.hpp"
  84 #include "gc/shared/weakProcessor.inline.hpp"
  85 #include "gc/shared/workerPolicy.hpp"
  86 #include "logging/log.hpp"
  87 #include "memory/allocation.hpp"
  88 #include "memory/iterator.hpp"
  89 #include "memory/resourceArea.hpp"
  90 #include "memory/universe.hpp"
  91 #include "oops/access.inline.hpp"
  92 #include "oops/compressedOops.inline.hpp"
  93 #include "oops/oop.inline.hpp"
  94 #include "runtime/atomic.hpp"
  95 #include "runtime/flags/flagSetting.hpp"
  96 #include "runtime/handles.inline.hpp"
  97 #include "runtime/init.hpp"
  98 #include "runtime/orderAccess.hpp"
  99 #include "runtime/threadSMR.hpp"
 100 #include "runtime/vmThread.hpp"
 101 #include "utilities/align.hpp"
 102 #include "utilities/bitMap.inline.hpp"
 103 #include "utilities/globalDefinitions.hpp"
 104 #include "utilities/stack.inline.hpp"
 105 
 106 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
 107 
 108 // INVARIANTS/NOTES
 109 //
 110 // All allocation activity covered by the G1CollectedHeap interface is
 111 // serialized by acquiring the HeapLock.  This happens in mem_allocate
 112 // and allocate_new_tlab, which are the "entry" points to the
 113 // allocation code from the rest of the JVM.  (Note that this does not
 114 // apply to TLAB allocation, which is not part of this interface: it
 115 // is done by clients of this interface.)
 116 
 117 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
 118  private:
 119   size_t _num_dirtied;
 120   G1CollectedHeap* _g1h;
 121   G1CardTable* _g1_ct;
 122 
 123   HeapRegion* region_for_card(CardValue* card_ptr) const {
 124     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
 125   }
 126 
 127   bool will_become_free(HeapRegion* hr) const {
 128     // A region will be freed by free_collection_set if the region is in the
 129     // collection set and has not had an evacuation failure.
 130     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 131   }
 132 
 133  public:
 134   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
 135     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
 136 
 137   void do_card_ptr(CardValue* card_ptr, uint worker_id) {
 138     HeapRegion* hr = region_for_card(card_ptr);
 139 
 140     // Should only dirty cards in regions that won't be freed.
 141     if (!will_become_free(hr)) {
 142       *card_ptr = G1CardTable::dirty_card_val();
 143       _num_dirtied++;
 144     }
 145   }
 146 
 147   size_t num_dirtied()   const { return _num_dirtied; }
 148 };
 149 
 150 
 151 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 152   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 153 }
 154 
 155 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 156   // The from card cache is not the memory that is actually committed. So we cannot
 157   // take advantage of the zero_filled parameter.
 158   reset_from_card_cache(start_idx, num_regions);
 159 }
 160 
 161 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
 162   Ticks start = Ticks::now();
 163   workers()->run_task(task, workers()->active_workers());
 164   return Ticks::now() - start;
 165 }
 166 
 167 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 168                                              MemRegion mr) {
 169   return new HeapRegion(hrs_index, bot(), mr);
 170 }
 171 
 172 // Private methods.
 173 
 174 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
 175                                         HeapRegionType type,
 176                                         bool do_expand,
 177                                         uint node_index) {
 178   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 179          "the only time we use this to allocate a humongous region is "
 180          "when we are allocating a single humongous region");
 181 
 182   HeapRegion* res = _hrm->allocate_free_region(type, node_index);
 183 
 184   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 185     // Currently, only attempts to allocate GC alloc regions set
 186     // do_expand to true. So, we should only reach here during a
 187     // safepoint. If this assumption changes we might have to
 188     // reconsider the use of _expand_heap_after_alloc_failure.
 189     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 190 
 191     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 192                               word_size * HeapWordSize);
 193 
 194     assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
 195            "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
 196            word_size * HeapWordSize);
 197     if (expand_single_region(node_index)) {
 198       // Given that expand_single_region() succeeded in expanding the heap, and we
 199       // always expand the heap by an amount aligned to the heap
 200       // region size, the free list should in theory not be empty.
 201       // In either case allocate_free_region() will check for NULL.
 202       res = _hrm->allocate_free_region(type, node_index);
 203     } else {
 204       _expand_heap_after_alloc_failure = false;
 205     }
 206   }
 207   return res;
 208 }
 209 
 210 HeapWord*
 211 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 212                                                            uint num_regions,
 213                                                            size_t word_size) {
 214   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 215   assert(is_humongous(word_size), "word_size should be humongous");
 216   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 217 
 218   // Index of last region in the series.
 219   uint last = first + num_regions - 1;
 220 
 221   // We need to initialize the region(s) we just discovered. This is
 222   // a bit tricky given that it can happen concurrently with
 223   // refinement threads refining cards on these regions and
 224   // potentially wanting to refine the BOT as they are scanning
 225   // those cards (this can happen shortly after a cleanup; see CR
 226   // 6991377). So we have to set up the region(s) carefully and in
 227   // a specific order.
 228 
 229   // The word size sum of all the regions we will allocate.
 230   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 231   assert(word_size <= word_size_sum, "sanity");
 232 
 233   // This will be the "starts humongous" region.
 234   HeapRegion* first_hr = region_at(first);
 235   // The header of the new object will be placed at the bottom of
 236   // the first region.
 237   HeapWord* new_obj = first_hr->bottom();
 238   // This will be the new top of the new object.
 239   HeapWord* obj_top = new_obj + word_size;
 240 
 241   // First, we need to zero the header of the space that we will be
 242   // allocating. When we update top further down, some refinement
 243   // threads might try to scan the region. By zeroing the header we
 244   // ensure that any thread that will try to scan the region will
 245   // come across the zero klass word and bail out.
 246   //
 247   // NOTE: It would not have been correct to have used
 248   // CollectedHeap::fill_with_object() and make the space look like
 249   // an int array. The thread that is doing the allocation will
 250   // later update the object header to a potentially different array
 251   // type and, for a very short period of time, the klass and length
 252   // fields will be inconsistent. This could cause a refinement
 253   // thread to calculate the object size incorrectly.
 254   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 255 
 256   // Next, pad out the unused tail of the last region with filler
 257   // objects, for improved usage accounting.
 258   // How many words we use for filler objects.
 259   size_t word_fill_size = word_size_sum - word_size;
 260 
 261   // How many words memory we "waste" which cannot hold a filler object.
 262   size_t words_not_fillable = 0;
 263 
 264   if (word_fill_size >= min_fill_size()) {
 265     fill_with_objects(obj_top, word_fill_size);
 266   } else if (word_fill_size > 0) {
 267     // We have space to fill, but we cannot fit an object there.
 268     words_not_fillable = word_fill_size;
 269     word_fill_size = 0;
 270   }
 271 
 272   // We will set up the first region as "starts humongous". This
 273   // will also update the BOT covering all the regions to reflect
 274   // that there is a single object that starts at the bottom of the
 275   // first region.
 276   first_hr->set_starts_humongous(obj_top, word_fill_size);
 277   _policy->remset_tracker()->update_at_allocate(first_hr);
 278   // Then, if there are any, we will set up the "continues
 279   // humongous" regions.
 280   HeapRegion* hr = NULL;
 281   for (uint i = first + 1; i <= last; ++i) {
 282     hr = region_at(i);
 283     hr->set_continues_humongous(first_hr);
 284     _policy->remset_tracker()->update_at_allocate(hr);
 285   }
 286 
 287   // Up to this point no concurrent thread would have been able to
 288   // do any scanning on any region in this series. All the top
 289   // fields still point to bottom, so the intersection between
 290   // [bottom,top] and [card_start,card_end] will be empty. Before we
 291   // update the top fields, we'll do a storestore to make sure that
 292   // no thread sees the update to top before the zeroing of the
 293   // object header and the BOT initialization.
 294   OrderAccess::storestore();
 295 
 296   // Now, we will update the top fields of the "continues humongous"
 297   // regions except the last one.
 298   for (uint i = first; i < last; ++i) {
 299     hr = region_at(i);
 300     hr->set_top(hr->end());
 301   }
 302 
 303   hr = region_at(last);
 304   // If we cannot fit a filler object, we must set top to the end
 305   // of the humongous object, otherwise we cannot iterate the heap
 306   // and the BOT will not be complete.
 307   hr->set_top(hr->end() - words_not_fillable);
 308 
 309   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 310          "obj_top should be in last region");
 311 
 312   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 313 
 314   assert(words_not_fillable == 0 ||
 315          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 316          "Miscalculation in humongous allocation");
 317 
 318   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 319 
 320   for (uint i = first; i <= last; ++i) {
 321     hr = region_at(i);
 322     _humongous_set.add(hr);
 323     _hr_printer.alloc(hr);
 324   }
 325 
 326   return new_obj;
 327 }
 328 
 329 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 330   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 331   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 332 }
 333 
 334 // If could fit into free regions w/o expansion, try.
 335 // Otherwise, if can expand, do so.
 336 // Otherwise, if using ex regions might help, try with ex given back.
 337 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 338   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 339 
 340   _verifier->verify_region_sets_optional();
 341 
 342   uint first = G1_NO_HRM_INDEX;
 343   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 344 
 345   if (obj_regions == 1) {
 346     // Only one region to allocate, try to use a fast path by directly allocating
 347     // from the free lists. Do not try to expand here, we will potentially do that
 348     // later.
 349     HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
 350     if (hr != NULL) {
 351       first = hr->hrm_index();
 352     }
 353   } else {
 354     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 355     // are lucky enough to find some.
 356     first = _hrm->find_contiguous_only_empty(obj_regions);
 357     if (first != G1_NO_HRM_INDEX) {
 358       _hrm->allocate_free_regions_starting_at(first, obj_regions);
 359     }
 360   }
 361 
 362   if (first == G1_NO_HRM_INDEX) {
 363     // Policy: We could not find enough regions for the humongous object in the
 364     // free list. Look through the heap to find a mix of free and uncommitted regions.
 365     // If so, try expansion.
 366     first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
 367     if (first != G1_NO_HRM_INDEX) {
 368       // We found something. Make sure these regions are committed, i.e. expand
 369       // the heap. Alternatively we could do a defragmentation GC.
 370       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 371                                     word_size * HeapWordSize);
 372 
 373       _hrm->expand_at(first, obj_regions, workers());
 374       policy()->record_new_heap_size(num_regions());
 375 
 376 #ifdef ASSERT
 377       for (uint i = first; i < first + obj_regions; ++i) {
 378         HeapRegion* hr = region_at(i);
 379         assert(hr->is_free(), "sanity");
 380         assert(hr->is_empty(), "sanity");
 381         assert(is_on_master_free_list(hr), "sanity");
 382       }
 383 #endif
 384       _hrm->allocate_free_regions_starting_at(first, obj_regions);
 385     } else {
 386       // Policy: Potentially trigger a defragmentation GC.
 387     }
 388   }
 389 
 390   HeapWord* result = NULL;
 391   if (first != G1_NO_HRM_INDEX) {
 392     result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
 393     assert(result != NULL, "it should always return a valid result");
 394 
 395     // A successful humongous object allocation changes the used space
 396     // information of the old generation so we need to recalculate the
 397     // sizes and update the jstat counters here.
 398     g1mm()->update_sizes();
 399   }
 400 
 401   _verifier->verify_region_sets_optional();
 402 
 403   return result;
 404 }
 405 
 406 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
 407                                              size_t requested_size,
 408                                              size_t* actual_size) {
 409   assert_heap_not_locked_and_not_at_safepoint();
 410   assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
 411 
 412   return attempt_allocation(min_size, requested_size, actual_size);
 413 }
 414 
 415 HeapWord*
 416 G1CollectedHeap::mem_allocate(size_t word_size,
 417                               bool*  gc_overhead_limit_was_exceeded) {
 418   assert_heap_not_locked_and_not_at_safepoint();
 419 
 420   if (is_humongous(word_size)) {
 421     return attempt_allocation_humongous(word_size);
 422   }
 423   size_t dummy = 0;
 424   return attempt_allocation(word_size, word_size, &dummy);
 425 }
 426 
 427 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 428   ResourceMark rm; // For retrieving the thread names in log messages.
 429 
 430   // Make sure you read the note in attempt_allocation_humongous().
 431 
 432   assert_heap_not_locked_and_not_at_safepoint();
 433   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 434          "be called for humongous allocation requests");
 435 
 436   // We should only get here after the first-level allocation attempt
 437   // (attempt_allocation()) failed to allocate.
 438 
 439   // We will loop until a) we manage to successfully perform the
 440   // allocation or b) we successfully schedule a collection which
 441   // fails to perform the allocation. b) is the only case when we'll
 442   // return NULL.
 443   HeapWord* result = NULL;
 444   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 445     bool should_try_gc;
 446     uint gc_count_before;
 447 
 448     {
 449       MutexLocker x(Heap_lock);
 450       result = _allocator->attempt_allocation_locked(word_size);
 451       if (result != NULL) {
 452         return result;
 453       }
 454 
 455       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 456       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 457       // waiting because the GCLocker is active to not wait too long.
 458       if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
 459         // No need for an ergo message here, can_expand_young_list() does this when
 460         // it returns true.
 461         result = _allocator->attempt_allocation_force(word_size);
 462         if (result != NULL) {
 463           return result;
 464         }
 465       }
 466       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 467       // the GCLocker initiated GC has been performed and then retry. This includes
 468       // the case when the GC Locker is not active but has not been performed.
 469       should_try_gc = !GCLocker::needs_gc();
 470       // Read the GC count while still holding the Heap_lock.
 471       gc_count_before = total_collections();
 472     }
 473 
 474     if (should_try_gc) {
 475       bool succeeded;
 476       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 477                                    GCCause::_g1_inc_collection_pause);
 478       if (result != NULL) {
 479         assert(succeeded, "only way to get back a non-NULL result");
 480         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 481                              Thread::current()->name(), p2i(result));
 482         return result;
 483       }
 484 
 485       if (succeeded) {
 486         // We successfully scheduled a collection which failed to allocate. No
 487         // point in trying to allocate further. We'll just return NULL.
 488         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 489                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 490         return NULL;
 491       }
 492       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 493                            Thread::current()->name(), word_size);
 494     } else {
 495       // Failed to schedule a collection.
 496       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 497         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 498                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 499         return NULL;
 500       }
 501       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 502       // The GCLocker is either active or the GCLocker initiated
 503       // GC has not yet been performed. Stall until it is and
 504       // then retry the allocation.
 505       GCLocker::stall_until_clear();
 506       gclocker_retry_count += 1;
 507     }
 508 
 509     // We can reach here if we were unsuccessful in scheduling a
 510     // collection (because another thread beat us to it) or if we were
 511     // stalled due to the GC locker. In either can we should retry the
 512     // allocation attempt in case another thread successfully
 513     // performed a collection and reclaimed enough space. We do the
 514     // first attempt (without holding the Heap_lock) here and the
 515     // follow-on attempt will be at the start of the next loop
 516     // iteration (after taking the Heap_lock).
 517     size_t dummy = 0;
 518     result = _allocator->attempt_allocation(word_size, word_size, &dummy);
 519     if (result != NULL) {
 520       return result;
 521     }
 522 
 523     // Give a warning if we seem to be looping forever.
 524     if ((QueuedAllocationWarningCount > 0) &&
 525         (try_count % QueuedAllocationWarningCount == 0)) {
 526       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 527                              Thread::current()->name(), try_count, word_size);
 528     }
 529   }
 530 
 531   ShouldNotReachHere();
 532   return NULL;
 533 }
 534 
 535 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 536   assert_at_safepoint_on_vm_thread();
 537   if (_archive_allocator == NULL) {
 538     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 539   }
 540 }
 541 
 542 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 543   // Allocations in archive regions cannot be of a size that would be considered
 544   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 545   // may be different at archive-restore time.
 546   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 547 }
 548 
 549 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 550   assert_at_safepoint_on_vm_thread();
 551   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 552   if (is_archive_alloc_too_large(word_size)) {
 553     return NULL;
 554   }
 555   return _archive_allocator->archive_mem_allocate(word_size);
 556 }
 557 
 558 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 559                                               size_t end_alignment_in_bytes) {
 560   assert_at_safepoint_on_vm_thread();
 561   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 562 
 563   // Call complete_archive to do the real work, filling in the MemRegion
 564   // array with the archive regions.
 565   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 566   delete _archive_allocator;
 567   _archive_allocator = NULL;
 568 }
 569 
 570 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 571   assert(ranges != NULL, "MemRegion array NULL");
 572   assert(count != 0, "No MemRegions provided");
 573   MemRegion reserved = _hrm->reserved();
 574   for (size_t i = 0; i < count; i++) {
 575     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 576       return false;
 577     }
 578   }
 579   return true;
 580 }
 581 
 582 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 583                                             size_t count,
 584                                             bool open) {
 585   assert(!is_init_completed(), "Expect to be called at JVM init time");
 586   assert(ranges != NULL, "MemRegion array NULL");
 587   assert(count != 0, "No MemRegions provided");
 588   MutexLocker x(Heap_lock);
 589 
 590   MemRegion reserved = _hrm->reserved();
 591   HeapWord* prev_last_addr = NULL;
 592   HeapRegion* prev_last_region = NULL;
 593 
 594   // Temporarily disable pretouching of heap pages. This interface is used
 595   // when mmap'ing archived heap data in, so pre-touching is wasted.
 596   FlagSetting fs(AlwaysPreTouch, false);
 597 
 598   // Enable archive object checking used by G1MarkSweep. We have to let it know
 599   // about each archive range, so that objects in those ranges aren't marked.
 600   G1ArchiveAllocator::enable_archive_object_check();
 601 
 602   // For each specified MemRegion range, allocate the corresponding G1
 603   // regions and mark them as archive regions. We expect the ranges
 604   // in ascending starting address order, without overlap.
 605   for (size_t i = 0; i < count; i++) {
 606     MemRegion curr_range = ranges[i];
 607     HeapWord* start_address = curr_range.start();
 608     size_t word_size = curr_range.word_size();
 609     HeapWord* last_address = curr_range.last();
 610     size_t commits = 0;
 611 
 612     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 613               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 614               p2i(start_address), p2i(last_address));
 615     guarantee(start_address > prev_last_addr,
 616               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 617               p2i(start_address), p2i(prev_last_addr));
 618     prev_last_addr = last_address;
 619 
 620     // Check for ranges that start in the same G1 region in which the previous
 621     // range ended, and adjust the start address so we don't try to allocate
 622     // the same region again. If the current range is entirely within that
 623     // region, skip it, just adjusting the recorded top.
 624     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 625     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 626       start_address = start_region->end();
 627       if (start_address > last_address) {
 628         increase_used(word_size * HeapWordSize);
 629         start_region->set_top(last_address + 1);
 630         continue;
 631       }
 632       start_region->set_top(start_address);
 633       curr_range = MemRegion(start_address, last_address + 1);
 634       start_region = _hrm->addr_to_region(start_address);
 635     }
 636 
 637     // Perform the actual region allocation, exiting if it fails.
 638     // Then note how much new space we have allocated.
 639     if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
 640       return false;
 641     }
 642     increase_used(word_size * HeapWordSize);
 643     if (commits != 0) {
 644       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 645                                 HeapRegion::GrainWords * HeapWordSize * commits);
 646 
 647     }
 648 
 649     // Mark each G1 region touched by the range as archive, add it to
 650     // the old set, and set top.
 651     HeapRegion* curr_region = _hrm->addr_to_region(start_address);
 652     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 653     prev_last_region = last_region;
 654 
 655     while (curr_region != NULL) {
 656       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 657              "Region already in use (index %u)", curr_region->hrm_index());
 658       if (open) {
 659         curr_region->set_open_archive();
 660       } else {
 661         curr_region->set_closed_archive();
 662       }
 663       _hr_printer.alloc(curr_region);
 664       _archive_set.add(curr_region);
 665       HeapWord* top;
 666       HeapRegion* next_region;
 667       if (curr_region != last_region) {
 668         top = curr_region->end();
 669         next_region = _hrm->next_region_in_heap(curr_region);
 670       } else {
 671         top = last_address + 1;
 672         next_region = NULL;
 673       }
 674       curr_region->set_top(top);
 675       curr_region = next_region;
 676     }
 677 
 678     // Notify mark-sweep of the archive
 679     G1ArchiveAllocator::set_range_archive(curr_range, open);
 680   }
 681   return true;
 682 }
 683 
 684 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 685   assert(!is_init_completed(), "Expect to be called at JVM init time");
 686   assert(ranges != NULL, "MemRegion array NULL");
 687   assert(count != 0, "No MemRegions provided");
 688   MemRegion reserved = _hrm->reserved();
 689   HeapWord *prev_last_addr = NULL;
 690   HeapRegion* prev_last_region = NULL;
 691 
 692   // For each MemRegion, create filler objects, if needed, in the G1 regions
 693   // that contain the address range. The address range actually within the
 694   // MemRegion will not be modified. That is assumed to have been initialized
 695   // elsewhere, probably via an mmap of archived heap data.
 696   MutexLocker x(Heap_lock);
 697   for (size_t i = 0; i < count; i++) {
 698     HeapWord* start_address = ranges[i].start();
 699     HeapWord* last_address = ranges[i].last();
 700 
 701     assert(reserved.contains(start_address) && reserved.contains(last_address),
 702            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 703            p2i(start_address), p2i(last_address));
 704     assert(start_address > prev_last_addr,
 705            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 706            p2i(start_address), p2i(prev_last_addr));
 707 
 708     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 709     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 710     HeapWord* bottom_address = start_region->bottom();
 711 
 712     // Check for a range beginning in the same region in which the
 713     // previous one ended.
 714     if (start_region == prev_last_region) {
 715       bottom_address = prev_last_addr + 1;
 716     }
 717 
 718     // Verify that the regions were all marked as archive regions by
 719     // alloc_archive_regions.
 720     HeapRegion* curr_region = start_region;
 721     while (curr_region != NULL) {
 722       guarantee(curr_region->is_archive(),
 723                 "Expected archive region at index %u", curr_region->hrm_index());
 724       if (curr_region != last_region) {
 725         curr_region = _hrm->next_region_in_heap(curr_region);
 726       } else {
 727         curr_region = NULL;
 728       }
 729     }
 730 
 731     prev_last_addr = last_address;
 732     prev_last_region = last_region;
 733 
 734     // Fill the memory below the allocated range with dummy object(s),
 735     // if the region bottom does not match the range start, or if the previous
 736     // range ended within the same G1 region, and there is a gap.
 737     if (start_address != bottom_address) {
 738       size_t fill_size = pointer_delta(start_address, bottom_address);
 739       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 740       increase_used(fill_size * HeapWordSize);
 741     }
 742   }
 743 }
 744 
 745 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
 746                                                      size_t desired_word_size,
 747                                                      size_t* actual_word_size) {
 748   assert_heap_not_locked_and_not_at_safepoint();
 749   assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
 750          "be called for humongous allocation requests");
 751 
 752   HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
 753 
 754   if (result == NULL) {
 755     *actual_word_size = desired_word_size;
 756     result = attempt_allocation_slow(desired_word_size);
 757   }
 758 
 759   assert_heap_not_locked();
 760   if (result != NULL) {
 761     assert(*actual_word_size != 0, "Actual size must have been set here");
 762     dirty_young_block(result, *actual_word_size);
 763   } else {
 764     *actual_word_size = 0;
 765   }
 766 
 767   return result;
 768 }
 769 
 770 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 771   assert(!is_init_completed(), "Expect to be called at JVM init time");
 772   assert(ranges != NULL, "MemRegion array NULL");
 773   assert(count != 0, "No MemRegions provided");
 774   MemRegion reserved = _hrm->reserved();
 775   HeapWord* prev_last_addr = NULL;
 776   HeapRegion* prev_last_region = NULL;
 777   size_t size_used = 0;
 778   size_t uncommitted_regions = 0;
 779 
 780   // For each Memregion, free the G1 regions that constitute it, and
 781   // notify mark-sweep that the range is no longer to be considered 'archive.'
 782   MutexLocker x(Heap_lock);
 783   for (size_t i = 0; i < count; i++) {
 784     HeapWord* start_address = ranges[i].start();
 785     HeapWord* last_address = ranges[i].last();
 786 
 787     assert(reserved.contains(start_address) && reserved.contains(last_address),
 788            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 789            p2i(start_address), p2i(last_address));
 790     assert(start_address > prev_last_addr,
 791            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 792            p2i(start_address), p2i(prev_last_addr));
 793     size_used += ranges[i].byte_size();
 794     prev_last_addr = last_address;
 795 
 796     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 797     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 798 
 799     // Check for ranges that start in the same G1 region in which the previous
 800     // range ended, and adjust the start address so we don't try to free
 801     // the same region again. If the current range is entirely within that
 802     // region, skip it.
 803     if (start_region == prev_last_region) {
 804       start_address = start_region->end();
 805       if (start_address > last_address) {
 806         continue;
 807       }
 808       start_region = _hrm->addr_to_region(start_address);
 809     }
 810     prev_last_region = last_region;
 811 
 812     // After verifying that each region was marked as an archive region by
 813     // alloc_archive_regions, set it free and empty and uncommit it.
 814     HeapRegion* curr_region = start_region;
 815     while (curr_region != NULL) {
 816       guarantee(curr_region->is_archive(),
 817                 "Expected archive region at index %u", curr_region->hrm_index());
 818       uint curr_index = curr_region->hrm_index();
 819       _archive_set.remove(curr_region);
 820       curr_region->set_free();
 821       curr_region->set_top(curr_region->bottom());
 822       if (curr_region != last_region) {
 823         curr_region = _hrm->next_region_in_heap(curr_region);
 824       } else {
 825         curr_region = NULL;
 826       }
 827       _hrm->shrink_at(curr_index, 1);
 828       uncommitted_regions++;
 829     }
 830 
 831     // Notify mark-sweep that this is no longer an archive range.
 832     G1ArchiveAllocator::clear_range_archive(ranges[i]);
 833   }
 834 
 835   if (uncommitted_regions != 0) {
 836     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 837                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 838   }
 839   decrease_used(size_used);
 840 }
 841 
 842 oop G1CollectedHeap::materialize_archived_object(oop obj) {
 843   assert(obj != NULL, "archived obj is NULL");
 844   assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
 845 
 846   // Loading an archived object makes it strongly reachable. If it is
 847   // loaded during concurrent marking, it must be enqueued to the SATB
 848   // queue, shading the previously white object gray.
 849   G1BarrierSet::enqueue(obj);
 850 
 851   return obj;
 852 }
 853 
 854 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 855   ResourceMark rm; // For retrieving the thread names in log messages.
 856 
 857   // The structure of this method has a lot of similarities to
 858   // attempt_allocation_slow(). The reason these two were not merged
 859   // into a single one is that such a method would require several "if
 860   // allocation is not humongous do this, otherwise do that"
 861   // conditional paths which would obscure its flow. In fact, an early
 862   // version of this code did use a unified method which was harder to
 863   // follow and, as a result, it had subtle bugs that were hard to
 864   // track down. So keeping these two methods separate allows each to
 865   // be more readable. It will be good to keep these two in sync as
 866   // much as possible.
 867 
 868   assert_heap_not_locked_and_not_at_safepoint();
 869   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 870          "should only be called for humongous allocations");
 871 
 872   // Humongous objects can exhaust the heap quickly, so we should check if we
 873   // need to start a marking cycle at each humongous object allocation. We do
 874   // the check before we do the actual allocation. The reason for doing it
 875   // before the allocation is that we avoid having to keep track of the newly
 876   // allocated memory while we do a GC.
 877   if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
 878                                            word_size)) {
 879     collect(GCCause::_g1_humongous_allocation);
 880   }
 881 
 882   // We will loop until a) we manage to successfully perform the
 883   // allocation or b) we successfully schedule a collection which
 884   // fails to perform the allocation. b) is the only case when we'll
 885   // return NULL.
 886   HeapWord* result = NULL;
 887   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 888     bool should_try_gc;
 889     uint gc_count_before;
 890 
 891 
 892     {
 893       MutexLocker x(Heap_lock);
 894 
 895       // Given that humongous objects are not allocated in young
 896       // regions, we'll first try to do the allocation without doing a
 897       // collection hoping that there's enough space in the heap.
 898       result = humongous_obj_allocate(word_size);
 899       if (result != NULL) {
 900         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 901         policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 902         return result;
 903       }
 904 
 905       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 906       // the GCLocker initiated GC has been performed and then retry. This includes
 907       // the case when the GC Locker is not active but has not been performed.
 908       should_try_gc = !GCLocker::needs_gc();
 909       // Read the GC count while still holding the Heap_lock.
 910       gc_count_before = total_collections();
 911     }
 912 
 913     if (should_try_gc) {
 914       bool succeeded;
 915       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 916                                    GCCause::_g1_humongous_allocation);
 917       if (result != NULL) {
 918         assert(succeeded, "only way to get back a non-NULL result");
 919         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 920                              Thread::current()->name(), p2i(result));
 921         return result;
 922       }
 923 
 924       if (succeeded) {
 925         // We successfully scheduled a collection which failed to allocate. No
 926         // point in trying to allocate further. We'll just return NULL.
 927         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 928                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 929         return NULL;
 930       }
 931       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 932                            Thread::current()->name(), word_size);
 933     } else {
 934       // Failed to schedule a collection.
 935       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 936         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 937                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 938         return NULL;
 939       }
 940       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 941       // The GCLocker is either active or the GCLocker initiated
 942       // GC has not yet been performed. Stall until it is and
 943       // then retry the allocation.
 944       GCLocker::stall_until_clear();
 945       gclocker_retry_count += 1;
 946     }
 947 
 948 
 949     // We can reach here if we were unsuccessful in scheduling a
 950     // collection (because another thread beat us to it) or if we were
 951     // stalled due to the GC locker. In either can we should retry the
 952     // allocation attempt in case another thread successfully
 953     // performed a collection and reclaimed enough space.
 954     // Humongous object allocation always needs a lock, so we wait for the retry
 955     // in the next iteration of the loop, unlike for the regular iteration case.
 956     // Give a warning if we seem to be looping forever.
 957 
 958     if ((QueuedAllocationWarningCount > 0) &&
 959         (try_count % QueuedAllocationWarningCount == 0)) {
 960       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 961                              Thread::current()->name(), try_count, word_size);
 962     }
 963   }
 964 
 965   ShouldNotReachHere();
 966   return NULL;
 967 }
 968 
 969 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 970                                                            bool expect_null_mutator_alloc_region) {
 971   assert_at_safepoint_on_vm_thread();
 972   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 973          "the current alloc region was unexpectedly found to be non-NULL");
 974 
 975   if (!is_humongous(word_size)) {
 976     return _allocator->attempt_allocation_locked(word_size);
 977   } else {
 978     HeapWord* result = humongous_obj_allocate(word_size);
 979     if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
 980       collector_state()->set_initiate_conc_mark_if_possible(true);
 981     }
 982     return result;
 983   }
 984 
 985   ShouldNotReachHere();
 986 }
 987 
 988 class PostCompactionPrinterClosure: public HeapRegionClosure {
 989 private:
 990   G1HRPrinter* _hr_printer;
 991 public:
 992   bool do_heap_region(HeapRegion* hr) {
 993     assert(!hr->is_young(), "not expecting to find young regions");
 994     _hr_printer->post_compaction(hr);
 995     return false;
 996   }
 997 
 998   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 999     : _hr_printer(hr_printer) { }
1000 };
1001 
1002 void G1CollectedHeap::print_hrm_post_compaction() {
1003   if (_hr_printer.is_active()) {
1004     PostCompactionPrinterClosure cl(hr_printer());
1005     heap_region_iterate(&cl);
1006   }
1007 }
1008 
1009 void G1CollectedHeap::abort_concurrent_cycle() {
1010   // If we start the compaction before the CM threads finish
1011   // scanning the root regions we might trip them over as we'll
1012   // be moving objects / updating references. So let's wait until
1013   // they are done. By telling them to abort, they should complete
1014   // early.
1015   _cm->root_regions()->abort();
1016   _cm->root_regions()->wait_until_scan_finished();
1017 
1018   // Disable discovery and empty the discovered lists
1019   // for the CM ref processor.
1020   _ref_processor_cm->disable_discovery();
1021   _ref_processor_cm->abandon_partial_discovery();
1022   _ref_processor_cm->verify_no_references_recorded();
1023 
1024   // Abandon current iterations of concurrent marking and concurrent
1025   // refinement, if any are in progress.
1026   concurrent_mark()->concurrent_cycle_abort();
1027 }
1028 
1029 void G1CollectedHeap::prepare_heap_for_full_collection() {
1030   // Make sure we'll choose a new allocation region afterwards.
1031   _allocator->release_mutator_alloc_regions();
1032   _allocator->abandon_gc_alloc_regions();
1033 
1034   // We may have added regions to the current incremental collection
1035   // set between the last GC or pause and now. We need to clear the
1036   // incremental collection set and then start rebuilding it afresh
1037   // after this full GC.
1038   abandon_collection_set(collection_set());
1039 
1040   tear_down_region_sets(false /* free_list_only */);
1041 
1042   hrm()->prepare_for_full_collection_start();
1043 }
1044 
1045 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1046   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1047   assert_used_and_recalculate_used_equal(this);
1048   _verifier->verify_region_sets_optional();
1049   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1050   _verifier->check_bitmaps("Full GC Start");
1051 }
1052 
1053 void G1CollectedHeap::prepare_heap_for_mutators() {
1054   hrm()->prepare_for_full_collection_end();
1055 
1056   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1057   ClassLoaderDataGraph::purge();
1058   MetaspaceUtils::verify_metrics();
1059 
1060   // Prepare heap for normal collections.
1061   assert(num_free_regions() == 0, "we should not have added any free regions");
1062   rebuild_region_sets(false /* free_list_only */);
1063   abort_refinement();
1064   resize_heap_if_necessary();
1065 
1066   // Rebuild the strong code root lists for each region
1067   rebuild_strong_code_roots();
1068 
1069   // Purge code root memory
1070   purge_code_root_memory();
1071 
1072   // Start a new incremental collection set for the next pause
1073   start_new_collection_set();
1074 
1075   _allocator->init_mutator_alloc_regions();
1076 
1077   // Post collection state updates.
1078   MetaspaceGC::compute_new_size();
1079 }
1080 
1081 void G1CollectedHeap::abort_refinement() {
1082   if (_hot_card_cache->use_cache()) {
1083     _hot_card_cache->reset_hot_cache();
1084   }
1085 
1086   // Discard all remembered set updates.
1087   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1088   assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1089          "DCQS should be empty");
1090 }
1091 
1092 void G1CollectedHeap::verify_after_full_collection() {
1093   _hrm->verify_optional();
1094   _verifier->verify_region_sets_optional();
1095   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1096   // Clear the previous marking bitmap, if needed for bitmap verification.
1097   // Note we cannot do this when we clear the next marking bitmap in
1098   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1099   // objects marked during a full GC against the previous bitmap.
1100   // But we need to clear it before calling check_bitmaps below since
1101   // the full GC has compacted objects and updated TAMS but not updated
1102   // the prev bitmap.
1103   if (G1VerifyBitmaps) {
1104     GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1105     _cm->clear_prev_bitmap(workers());
1106   }
1107   // This call implicitly verifies that the next bitmap is clear after Full GC.
1108   _verifier->check_bitmaps("Full GC End");
1109 
1110   // At this point there should be no regions in the
1111   // entire heap tagged as young.
1112   assert(check_young_list_empty(), "young list should be empty at this point");
1113 
1114   // Note: since we've just done a full GC, concurrent
1115   // marking is no longer active. Therefore we need not
1116   // re-enable reference discovery for the CM ref processor.
1117   // That will be done at the start of the next marking cycle.
1118   // We also know that the STW processor should no longer
1119   // discover any new references.
1120   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1121   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1122   _ref_processor_stw->verify_no_references_recorded();
1123   _ref_processor_cm->verify_no_references_recorded();
1124 }
1125 
1126 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1127   // Post collection logging.
1128   // We should do this after we potentially resize the heap so
1129   // that all the COMMIT / UNCOMMIT events are generated before
1130   // the compaction events.
1131   print_hrm_post_compaction();
1132   heap_transition->print();
1133   print_heap_after_gc();
1134   print_heap_regions();
1135 }
1136 
1137 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1138                                          bool clear_all_soft_refs) {
1139   assert_at_safepoint_on_vm_thread();
1140 
1141   if (GCLocker::check_active_before_gc()) {
1142     // Full GC was not completed.
1143     return false;
1144   }
1145 
1146   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1147       soft_ref_policy()->should_clear_all_soft_refs();
1148 
1149   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1150   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1151 
1152   collector.prepare_collection();
1153   collector.collect();
1154   collector.complete_collection();
1155 
1156   // Full collection was successfully completed.
1157   return true;
1158 }
1159 
1160 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1161   // Currently, there is no facility in the do_full_collection(bool) API to notify
1162   // the caller that the collection did not succeed (e.g., because it was locked
1163   // out by the GC locker). So, right now, we'll ignore the return value.
1164   bool dummy = do_full_collection(true,                /* explicit_gc */
1165                                   clear_all_soft_refs);
1166 }
1167 
1168 void G1CollectedHeap::resize_heap_if_necessary() {
1169   assert_at_safepoint_on_vm_thread();
1170 
1171   // Capacity, free and used after the GC counted as full regions to
1172   // include the waste in the following calculations.
1173   const size_t capacity_after_gc = capacity();
1174   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1175 
1176   // This is enforced in arguments.cpp.
1177   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1178          "otherwise the code below doesn't make sense");
1179 
1180   // We don't have floating point command-line arguments
1181   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1182   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1183   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1184   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1185 
1186   // We have to be careful here as these two calculations can overflow
1187   // 32-bit size_t's.
1188   double used_after_gc_d = (double) used_after_gc;
1189   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1190   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1191 
1192   // Let's make sure that they are both under the max heap size, which
1193   // by default will make them fit into a size_t.
1194   double desired_capacity_upper_bound = (double) MaxHeapSize;
1195   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1196                                     desired_capacity_upper_bound);
1197   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1198                                     desired_capacity_upper_bound);
1199 
1200   // We can now safely turn them into size_t's.
1201   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1202   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1203 
1204   // This assert only makes sense here, before we adjust them
1205   // with respect to the min and max heap size.
1206   assert(minimum_desired_capacity <= maximum_desired_capacity,
1207          "minimum_desired_capacity = " SIZE_FORMAT ", "
1208          "maximum_desired_capacity = " SIZE_FORMAT,
1209          minimum_desired_capacity, maximum_desired_capacity);
1210 
1211   // Should not be greater than the heap max size. No need to adjust
1212   // it with respect to the heap min size as it's a lower bound (i.e.,
1213   // we'll try to make the capacity larger than it, not smaller).
1214   minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1215   // Should not be less than the heap min size. No need to adjust it
1216   // with respect to the heap max size as it's an upper bound (i.e.,
1217   // we'll try to make the capacity smaller than it, not greater).
1218   maximum_desired_capacity =  MAX2(maximum_desired_capacity, MinHeapSize);
1219 
1220   if (capacity_after_gc < minimum_desired_capacity) {
1221     // Don't expand unless it's significant
1222     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1223 
1224     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1225                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1226                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1227                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1228 
1229     expand(expand_bytes, _workers);
1230 
1231     // No expansion, now see if we want to shrink
1232   } else if (capacity_after_gc > maximum_desired_capacity) {
1233     // Capacity too large, compute shrinking size
1234     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1235 
1236     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1237                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1238                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1239                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1240 
1241     shrink(shrink_bytes);
1242   }
1243 }
1244 
1245 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1246                                                             bool do_gc,
1247                                                             bool clear_all_soft_refs,
1248                                                             bool expect_null_mutator_alloc_region,
1249                                                             bool* gc_succeeded) {
1250   *gc_succeeded = true;
1251   // Let's attempt the allocation first.
1252   HeapWord* result =
1253     attempt_allocation_at_safepoint(word_size,
1254                                     expect_null_mutator_alloc_region);
1255   if (result != NULL) {
1256     return result;
1257   }
1258 
1259   // In a G1 heap, we're supposed to keep allocation from failing by
1260   // incremental pauses.  Therefore, at least for now, we'll favor
1261   // expansion over collection.  (This might change in the future if we can
1262   // do something smarter than full collection to satisfy a failed alloc.)
1263   result = expand_and_allocate(word_size);
1264   if (result != NULL) {
1265     return result;
1266   }
1267 
1268   if (do_gc) {
1269     // Expansion didn't work, we'll try to do a Full GC.
1270     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1271                                        clear_all_soft_refs);
1272   }
1273 
1274   return NULL;
1275 }
1276 
1277 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1278                                                      bool* succeeded) {
1279   assert_at_safepoint_on_vm_thread();
1280 
1281   // Attempts to allocate followed by Full GC.
1282   HeapWord* result =
1283     satisfy_failed_allocation_helper(word_size,
1284                                      true,  /* do_gc */
1285                                      false, /* clear_all_soft_refs */
1286                                      false, /* expect_null_mutator_alloc_region */
1287                                      succeeded);
1288 
1289   if (result != NULL || !*succeeded) {
1290     return result;
1291   }
1292 
1293   // Attempts to allocate followed by Full GC that will collect all soft references.
1294   result = satisfy_failed_allocation_helper(word_size,
1295                                             true, /* do_gc */
1296                                             true, /* clear_all_soft_refs */
1297                                             true, /* expect_null_mutator_alloc_region */
1298                                             succeeded);
1299 
1300   if (result != NULL || !*succeeded) {
1301     return result;
1302   }
1303 
1304   // Attempts to allocate, no GC
1305   result = satisfy_failed_allocation_helper(word_size,
1306                                             false, /* do_gc */
1307                                             false, /* clear_all_soft_refs */
1308                                             true,  /* expect_null_mutator_alloc_region */
1309                                             succeeded);
1310 
1311   if (result != NULL) {
1312     return result;
1313   }
1314 
1315   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1316          "Flag should have been handled and cleared prior to this point");
1317 
1318   // What else?  We might try synchronous finalization later.  If the total
1319   // space available is large enough for the allocation, then a more
1320   // complete compaction phase than we've tried so far might be
1321   // appropriate.
1322   return NULL;
1323 }
1324 
1325 // Attempting to expand the heap sufficiently
1326 // to support an allocation of the given "word_size".  If
1327 // successful, perform the allocation and return the address of the
1328 // allocated block, or else "NULL".
1329 
1330 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1331   assert_at_safepoint_on_vm_thread();
1332 
1333   _verifier->verify_region_sets_optional();
1334 
1335   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1336   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1337                             word_size * HeapWordSize);
1338 
1339 
1340   if (expand(expand_bytes, _workers)) {
1341     _hrm->verify_optional();
1342     _verifier->verify_region_sets_optional();
1343     return attempt_allocation_at_safepoint(word_size,
1344                                            false /* expect_null_mutator_alloc_region */);
1345   }
1346   return NULL;
1347 }
1348 
1349 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1350   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1351   aligned_expand_bytes = align_up(aligned_expand_bytes,
1352                                        HeapRegion::GrainBytes);
1353 
1354   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1355                             expand_bytes, aligned_expand_bytes);
1356 
1357   if (is_maximal_no_gc()) {
1358     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1359     return false;
1360   }
1361 
1362   double expand_heap_start_time_sec = os::elapsedTime();
1363   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1364   assert(regions_to_expand > 0, "Must expand by at least one region");
1365 
1366   uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1367   if (expand_time_ms != NULL) {
1368     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1369   }
1370 
1371   if (expanded_by > 0) {
1372     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1373     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1374     policy()->record_new_heap_size(num_regions());
1375   } else {
1376     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1377 
1378     // The expansion of the virtual storage space was unsuccessful.
1379     // Let's see if it was because we ran out of swap.
1380     if (G1ExitOnExpansionFailure &&
1381         _hrm->available() >= regions_to_expand) {
1382       // We had head room...
1383       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1384     }
1385   }
1386   return regions_to_expand > 0;
1387 }
1388 
1389 bool G1CollectedHeap::expand_single_region(uint node_index) {
1390   uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1391 
1392   if (expanded_by == 0) {
1393     assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1394     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1395     return false;
1396   }
1397 
1398   policy()->record_new_heap_size(num_regions());
1399   return true;
1400 }
1401 
1402 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1403   size_t aligned_shrink_bytes =
1404     ReservedSpace::page_align_size_down(shrink_bytes);
1405   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1406                                          HeapRegion::GrainBytes);
1407   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1408 
1409   uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1410   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1411 
1412   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",
1413                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1414   if (num_regions_removed > 0) {
1415     policy()->record_new_heap_size(num_regions());
1416   } else {
1417     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1418   }
1419 }
1420 
1421 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1422   _verifier->verify_region_sets_optional();
1423 
1424   // We should only reach here at the end of a Full GC or during Remark which
1425   // means we should not not be holding to any GC alloc regions. The method
1426   // below will make sure of that and do any remaining clean up.
1427   _allocator->abandon_gc_alloc_regions();
1428 
1429   // Instead of tearing down / rebuilding the free lists here, we
1430   // could instead use the remove_all_pending() method on free_list to
1431   // remove only the ones that we need to remove.
1432   tear_down_region_sets(true /* free_list_only */);
1433   shrink_helper(shrink_bytes);
1434   rebuild_region_sets(true /* free_list_only */);
1435 
1436   _hrm->verify_optional();
1437   _verifier->verify_region_sets_optional();
1438 }
1439 
1440 class OldRegionSetChecker : public HeapRegionSetChecker {
1441 public:
1442   void check_mt_safety() {
1443     // Master Old Set MT safety protocol:
1444     // (a) If we're at a safepoint, operations on the master old set
1445     // should be invoked:
1446     // - by the VM thread (which will serialize them), or
1447     // - by the GC workers while holding the FreeList_lock, if we're
1448     //   at a safepoint for an evacuation pause (this lock is taken
1449     //   anyway when an GC alloc region is retired so that a new one
1450     //   is allocated from the free list), or
1451     // - by the GC workers while holding the OldSets_lock, if we're at a
1452     //   safepoint for a cleanup pause.
1453     // (b) If we're not at a safepoint, operations on the master old set
1454     // should be invoked while holding the Heap_lock.
1455 
1456     if (SafepointSynchronize::is_at_safepoint()) {
1457       guarantee(Thread::current()->is_VM_thread() ||
1458                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1459                 "master old set MT safety protocol at a safepoint");
1460     } else {
1461       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1462     }
1463   }
1464   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1465   const char* get_description() { return "Old Regions"; }
1466 };
1467 
1468 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1469 public:
1470   void check_mt_safety() {
1471     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1472               "May only change archive regions during initialization or safepoint.");
1473   }
1474   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1475   const char* get_description() { return "Archive Regions"; }
1476 };
1477 
1478 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1479 public:
1480   void check_mt_safety() {
1481     // Humongous Set MT safety protocol:
1482     // (a) If we're at a safepoint, operations on the master humongous
1483     // set should be invoked by either the VM thread (which will
1484     // serialize them) or by the GC workers while holding the
1485     // OldSets_lock.
1486     // (b) If we're not at a safepoint, operations on the master
1487     // humongous set should be invoked while holding the Heap_lock.
1488 
1489     if (SafepointSynchronize::is_at_safepoint()) {
1490       guarantee(Thread::current()->is_VM_thread() ||
1491                 OldSets_lock->owned_by_self(),
1492                 "master humongous set MT safety protocol at a safepoint");
1493     } else {
1494       guarantee(Heap_lock->owned_by_self(),
1495                 "master humongous set MT safety protocol outside a safepoint");
1496     }
1497   }
1498   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1499   const char* get_description() { return "Humongous Regions"; }
1500 };
1501 
1502 G1CollectedHeap::G1CollectedHeap() :
1503   CollectedHeap(),
1504   _young_gen_sampling_thread(NULL),
1505   _workers(NULL),
1506   _card_table(NULL),
1507   _soft_ref_policy(),
1508   _old_set("Old Region Set", new OldRegionSetChecker()),
1509   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1510   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1511   _bot(NULL),
1512   _listener(),
1513   _numa(G1NUMA::create()),
1514   _hrm(NULL),
1515   _allocator(NULL),
1516   _verifier(NULL),
1517   _summary_bytes_used(0),
1518   _bytes_used_during_gc(0),
1519   _archive_allocator(NULL),
1520   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1521   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1522   _expand_heap_after_alloc_failure(true),
1523   _g1mm(NULL),
1524   _humongous_reclaim_candidates(),
1525   _has_humongous_reclaim_candidates(false),
1526   _hr_printer(),
1527   _collector_state(),
1528   _old_marking_cycles_started(0),
1529   _old_marking_cycles_completed(0),
1530   _eden(),
1531   _survivor(),
1532   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1533   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1534   _policy(G1Policy::create_policy(_gc_timer_stw)),
1535   _heap_sizing_policy(NULL),
1536   _collection_set(this, _policy),
1537   _hot_card_cache(NULL),
1538   _rem_set(NULL),
1539   _cm(NULL),
1540   _cm_thread(NULL),
1541   _cr(NULL),
1542   _task_queues(NULL),
1543   _evacuation_failed(false),
1544   _evacuation_failed_info_array(NULL),
1545   _preserved_marks_set(true /* in_c_heap */),
1546 #ifndef PRODUCT
1547   _evacuation_failure_alot_for_current_gc(false),
1548   _evacuation_failure_alot_gc_number(0),
1549   _evacuation_failure_alot_count(0),
1550 #endif
1551   _ref_processor_stw(NULL),
1552   _is_alive_closure_stw(this),
1553   _is_subject_to_discovery_stw(this),
1554   _ref_processor_cm(NULL),
1555   _is_alive_closure_cm(this),
1556   _is_subject_to_discovery_cm(this),
1557   _region_attr() {
1558 
1559   _verifier = new G1HeapVerifier(this);
1560 
1561   _allocator = new G1Allocator(this);
1562 
1563   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1564 
1565   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1566 
1567   // Override the default _filler_array_max_size so that no humongous filler
1568   // objects are created.
1569   _filler_array_max_size = _humongous_object_threshold_in_words;
1570 
1571   uint n_queues = ParallelGCThreads;
1572   _task_queues = new RefToScanQueueSet(n_queues);
1573 
1574   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1575 
1576   for (uint i = 0; i < n_queues; i++) {
1577     RefToScanQueue* q = new RefToScanQueue();
1578     q->initialize();
1579     _task_queues->register_queue(i, q);
1580     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1581   }
1582 
1583   // Initialize the G1EvacuationFailureALot counters and flags.
1584   NOT_PRODUCT(reset_evacuation_should_fail();)
1585   _gc_tracer_stw->initialize();
1586 
1587   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1588 }
1589 
1590 static size_t actual_reserved_page_size(ReservedSpace rs) {
1591   size_t page_size = os::vm_page_size();
1592   if (UseLargePages) {
1593     // There are two ways to manage large page memory.
1594     // 1. OS supports committing large page memory.
1595     // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1596     //    And ReservedSpace calls it 'special'. If we failed to set 'special',
1597     //    we reserved memory without large page.
1598     if (os::can_commit_large_page_memory() || rs.special()) {
1599       // An alignment at ReservedSpace comes from preferred page size or
1600       // heap alignment, and if the alignment came from heap alignment, it could be
1601       // larger than large pages size. So need to cap with the large page size.
1602       page_size = MIN2(rs.alignment(), os::large_page_size());
1603     }
1604   }
1605 
1606   return page_size;
1607 }
1608 
1609 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1610                                                                  size_t size,
1611                                                                  size_t translation_factor) {
1612   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1613   // Allocate a new reserved space, preferring to use large pages.
1614   ReservedSpace rs(size, preferred_page_size);
1615   size_t page_size = actual_reserved_page_size(rs);
1616   G1RegionToSpaceMapper* result  =
1617     G1RegionToSpaceMapper::create_mapper(rs,
1618                                          size,
1619                                          page_size,
1620                                          HeapRegion::GrainBytes,
1621                                          translation_factor,
1622                                          mtGC);
1623 
1624   os::trace_page_sizes_for_requested_size(description,
1625                                           size,
1626                                           preferred_page_size,
1627                                           page_size,
1628                                           rs.base(),
1629                                           rs.size());
1630 
1631   return result;
1632 }
1633 
1634 jint G1CollectedHeap::initialize_concurrent_refinement() {
1635   jint ecode = JNI_OK;
1636   _cr = G1ConcurrentRefine::create(&ecode);
1637   return ecode;
1638 }
1639 
1640 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1641   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1642   if (_young_gen_sampling_thread->osthread() == NULL) {
1643     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1644     return JNI_ENOMEM;
1645   }
1646   return JNI_OK;
1647 }
1648 
1649 jint G1CollectedHeap::initialize() {
1650 
1651   // Necessary to satisfy locking discipline assertions.
1652 
1653   MutexLocker x(Heap_lock);
1654 
1655   // While there are no constraints in the GC code that HeapWordSize
1656   // be any particular value, there are multiple other areas in the
1657   // system which believe this to be true (e.g. oop->object_size in some
1658   // cases incorrectly returns the size in wordSize units rather than
1659   // HeapWordSize).
1660   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1661 
1662   size_t init_byte_size = InitialHeapSize;
1663   size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1664 
1665   // Ensure that the sizes are properly aligned.
1666   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1667   Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1668   Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1669 
1670   // Reserve the maximum.
1671 
1672   // When compressed oops are enabled, the preferred heap base
1673   // is calculated by subtracting the requested size from the
1674   // 32Gb boundary and using the result as the base address for
1675   // heap reservation. If the requested size is not aligned to
1676   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1677   // into the ReservedHeapSpace constructor) then the actual
1678   // base of the reserved heap may end up differing from the
1679   // address that was requested (i.e. the preferred heap base).
1680   // If this happens then we could end up using a non-optimal
1681   // compressed oops mode.
1682 
1683   ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1684                                                      HeapAlignment);
1685 
1686   initialize_reserved_region(heap_rs);
1687 
1688   // Create the barrier set for the entire reserved region.
1689   G1CardTable* ct = new G1CardTable(heap_rs.region());
1690   ct->initialize();
1691   G1BarrierSet* bs = new G1BarrierSet(ct);
1692   bs->initialize();
1693   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1694   BarrierSet::set_barrier_set(bs);
1695   _card_table = ct;
1696 
1697   {
1698     G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1699     satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1700     satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1701   }
1702 
1703   // Create the hot card cache.
1704   _hot_card_cache = new G1HotCardCache(this);
1705 
1706   // Carve out the G1 part of the heap.
1707   ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1708   size_t page_size = actual_reserved_page_size(heap_rs);
1709   G1RegionToSpaceMapper* heap_storage =
1710     G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1711                                               g1_rs.size(),
1712                                               page_size,
1713                                               HeapRegion::GrainBytes,
1714                                               1,
1715                                               mtJavaHeap);
1716   if(heap_storage == NULL) {
1717     vm_shutdown_during_initialization("Could not initialize G1 heap");
1718     return JNI_ERR;
1719   }
1720 
1721   os::trace_page_sizes("Heap",
1722                        MinHeapSize,
1723                        reserved_byte_size,
1724                        page_size,
1725                        heap_rs.base(),
1726                        heap_rs.size());
1727   heap_storage->set_mapping_changed_listener(&_listener);
1728 
1729   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1730   G1RegionToSpaceMapper* bot_storage =
1731     create_aux_memory_mapper("Block Offset Table",
1732                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1733                              G1BlockOffsetTable::heap_map_factor());
1734 
1735   G1RegionToSpaceMapper* cardtable_storage =
1736     create_aux_memory_mapper("Card Table",
1737                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1738                              G1CardTable::heap_map_factor());
1739 
1740   G1RegionToSpaceMapper* card_counts_storage =
1741     create_aux_memory_mapper("Card Counts Table",
1742                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1743                              G1CardCounts::heap_map_factor());
1744 
1745   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1746   G1RegionToSpaceMapper* prev_bitmap_storage =
1747     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1748   G1RegionToSpaceMapper* next_bitmap_storage =
1749     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1750 
1751   _hrm = HeapRegionManager::create_manager(this);
1752 
1753   _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1754   _card_table->initialize(cardtable_storage);
1755 
1756   // Do later initialization work for concurrent refinement.
1757   _hot_card_cache->initialize(card_counts_storage);
1758 
1759   // 6843694 - ensure that the maximum region index can fit
1760   // in the remembered set structures.
1761   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1762   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1763 
1764   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1765   // start within the first card.
1766   guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1767   // Also create a G1 rem set.
1768   _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1769   _rem_set->initialize(max_reserved_capacity(), max_regions());
1770 
1771   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1772   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1773   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1774             "too many cards per region");
1775 
1776   FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1777 
1778   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1779 
1780   {
1781     HeapWord* start = _hrm->reserved().start();
1782     HeapWord* end = _hrm->reserved().end();
1783     size_t granularity = HeapRegion::GrainBytes;
1784 
1785     _region_attr.initialize(start, end, granularity);
1786     _humongous_reclaim_candidates.initialize(start, end, granularity);
1787   }
1788 
1789   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1790                           true /* are_GC_task_threads */,
1791                           false /* are_ConcurrentGC_threads */);
1792   if (_workers == NULL) {
1793     return JNI_ENOMEM;
1794   }
1795   _workers->initialize_workers();
1796 
1797   _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1798 
1799   // Create the G1ConcurrentMark data structure and thread.
1800   // (Must do this late, so that "max_regions" is defined.)
1801   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1802   if (_cm == NULL || !_cm->completed_initialization()) {
1803     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1804     return JNI_ENOMEM;
1805   }
1806   _cm_thread = _cm->cm_thread();
1807 
1808   // Now expand into the initial heap size.
1809   if (!expand(init_byte_size, _workers)) {
1810     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1811     return JNI_ENOMEM;
1812   }
1813 
1814   // Perform any initialization actions delegated to the policy.
1815   policy()->init(this, &_collection_set);
1816 
1817   jint ecode = initialize_concurrent_refinement();
1818   if (ecode != JNI_OK) {
1819     return ecode;
1820   }
1821 
1822   ecode = initialize_young_gen_sampling_thread();
1823   if (ecode != JNI_OK) {
1824     return ecode;
1825   }
1826 
1827   {
1828     G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1829     dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1830     dcqs.set_max_cards(concurrent_refine()->red_zone());
1831   }
1832 
1833   // Here we allocate the dummy HeapRegion that is required by the
1834   // G1AllocRegion class.
1835   HeapRegion* dummy_region = _hrm->get_dummy_region();
1836 
1837   // We'll re-use the same region whether the alloc region will
1838   // require BOT updates or not and, if it doesn't, then a non-young
1839   // region will complain that it cannot support allocations without
1840   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1841   dummy_region->set_eden();
1842   // Make sure it's full.
1843   dummy_region->set_top(dummy_region->end());
1844   G1AllocRegion::setup(this, dummy_region);
1845 
1846   _allocator->init_mutator_alloc_regions();
1847 
1848   // Do create of the monitoring and management support so that
1849   // values in the heap have been properly initialized.
1850   _g1mm = new G1MonitoringSupport(this);
1851 
1852   G1StringDedup::initialize();
1853 
1854   _preserved_marks_set.init(ParallelGCThreads);
1855 
1856   _collection_set.initialize(max_regions());
1857 
1858   return JNI_OK;
1859 }
1860 
1861 void G1CollectedHeap::stop() {
1862   // Stop all concurrent threads. We do this to make sure these threads
1863   // do not continue to execute and access resources (e.g. logging)
1864   // that are destroyed during shutdown.
1865   _cr->stop();
1866   _young_gen_sampling_thread->stop();
1867   _cm_thread->stop();
1868   if (G1StringDedup::is_enabled()) {
1869     G1StringDedup::stop();
1870   }
1871 }
1872 
1873 void G1CollectedHeap::safepoint_synchronize_begin() {
1874   SuspendibleThreadSet::synchronize();
1875 }
1876 
1877 void G1CollectedHeap::safepoint_synchronize_end() {
1878   SuspendibleThreadSet::desynchronize();
1879 }
1880 
1881 void G1CollectedHeap::post_initialize() {
1882   CollectedHeap::post_initialize();
1883   ref_processing_init();
1884 }
1885 
1886 void G1CollectedHeap::ref_processing_init() {
1887   // Reference processing in G1 currently works as follows:
1888   //
1889   // * There are two reference processor instances. One is
1890   //   used to record and process discovered references
1891   //   during concurrent marking; the other is used to
1892   //   record and process references during STW pauses
1893   //   (both full and incremental).
1894   // * Both ref processors need to 'span' the entire heap as
1895   //   the regions in the collection set may be dotted around.
1896   //
1897   // * For the concurrent marking ref processor:
1898   //   * Reference discovery is enabled at initial marking.
1899   //   * Reference discovery is disabled and the discovered
1900   //     references processed etc during remarking.
1901   //   * Reference discovery is MT (see below).
1902   //   * Reference discovery requires a barrier (see below).
1903   //   * Reference processing may or may not be MT
1904   //     (depending on the value of ParallelRefProcEnabled
1905   //     and ParallelGCThreads).
1906   //   * A full GC disables reference discovery by the CM
1907   //     ref processor and abandons any entries on it's
1908   //     discovered lists.
1909   //
1910   // * For the STW processor:
1911   //   * Non MT discovery is enabled at the start of a full GC.
1912   //   * Processing and enqueueing during a full GC is non-MT.
1913   //   * During a full GC, references are processed after marking.
1914   //
1915   //   * Discovery (may or may not be MT) is enabled at the start
1916   //     of an incremental evacuation pause.
1917   //   * References are processed near the end of a STW evacuation pause.
1918   //   * For both types of GC:
1919   //     * Discovery is atomic - i.e. not concurrent.
1920   //     * Reference discovery will not need a barrier.
1921 
1922   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1923 
1924   // Concurrent Mark ref processor
1925   _ref_processor_cm =
1926     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1927                            mt_processing,                                  // mt processing
1928                            ParallelGCThreads,                              // degree of mt processing
1929                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1930                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1931                            false,                                          // Reference discovery is not atomic
1932                            &_is_alive_closure_cm,                          // is alive closure
1933                            true);                                          // allow changes to number of processing threads
1934 
1935   // STW ref processor
1936   _ref_processor_stw =
1937     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1938                            mt_processing,                        // mt processing
1939                            ParallelGCThreads,                    // degree of mt processing
1940                            (ParallelGCThreads > 1),              // mt discovery
1941                            ParallelGCThreads,                    // degree of mt discovery
1942                            true,                                 // Reference discovery is atomic
1943                            &_is_alive_closure_stw,               // is alive closure
1944                            true);                                // allow changes to number of processing threads
1945 }
1946 
1947 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1948   return &_soft_ref_policy;
1949 }
1950 
1951 size_t G1CollectedHeap::capacity() const {
1952   return _hrm->length() * HeapRegion::GrainBytes;
1953 }
1954 
1955 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1956   return _hrm->total_free_bytes();
1957 }
1958 
1959 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1960   _hot_card_cache->drain(cl, worker_id);
1961 }
1962 
1963 // Computes the sum of the storage used by the various regions.
1964 size_t G1CollectedHeap::used() const {
1965   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1966   if (_archive_allocator != NULL) {
1967     result += _archive_allocator->used();
1968   }
1969   return result;
1970 }
1971 
1972 size_t G1CollectedHeap::used_unlocked() const {
1973   return _summary_bytes_used;
1974 }
1975 
1976 class SumUsedClosure: public HeapRegionClosure {
1977   size_t _used;
1978 public:
1979   SumUsedClosure() : _used(0) {}
1980   bool do_heap_region(HeapRegion* r) {
1981     _used += r->used();
1982     return false;
1983   }
1984   size_t result() { return _used; }
1985 };
1986 
1987 size_t G1CollectedHeap::recalculate_used() const {
1988   SumUsedClosure blk;
1989   heap_region_iterate(&blk);
1990   return blk.result();
1991 }
1992 
1993 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1994   switch (cause) {
1995     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1996     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1997     case GCCause::_wb_conc_mark:                        return true;
1998     default :                                           return false;
1999   }
2000 }
2001 
2002 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2003   switch (cause) {
2004     case GCCause::_g1_humongous_allocation: return true;
2005     case GCCause::_g1_periodic_collection:  return G1PeriodicGCInvokesConcurrent;
2006     default:                                return is_user_requested_concurrent_full_gc(cause);
2007   }
2008 }
2009 
2010 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2011   if (policy()->force_upgrade_to_full()) {
2012     return true;
2013   } else if (should_do_concurrent_full_gc(_gc_cause)) {
2014     return false;
2015   } else if (has_regions_left_for_allocation()) {
2016     return false;
2017   } else {
2018     return true;
2019   }
2020 }
2021 
2022 #ifndef PRODUCT
2023 void G1CollectedHeap::allocate_dummy_regions() {
2024   // Let's fill up most of the region
2025   size_t word_size = HeapRegion::GrainWords - 1024;
2026   // And as a result the region we'll allocate will be humongous.
2027   guarantee(is_humongous(word_size), "sanity");
2028 
2029   // _filler_array_max_size is set to humongous object threshold
2030   // but temporarily change it to use CollectedHeap::fill_with_object().
2031   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2032 
2033   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2034     // Let's use the existing mechanism for the allocation
2035     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2036     if (dummy_obj != NULL) {
2037       MemRegion mr(dummy_obj, word_size);
2038       CollectedHeap::fill_with_object(mr);
2039     } else {
2040       // If we can't allocate once, we probably cannot allocate
2041       // again. Let's get out of the loop.
2042       break;
2043     }
2044   }
2045 }
2046 #endif // !PRODUCT
2047 
2048 void G1CollectedHeap::increment_old_marking_cycles_started() {
2049   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2050          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2051          "Wrong marking cycle count (started: %d, completed: %d)",
2052          _old_marking_cycles_started, _old_marking_cycles_completed);
2053 
2054   _old_marking_cycles_started++;
2055 }
2056 
2057 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2058   MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
2059 
2060   // We assume that if concurrent == true, then the caller is a
2061   // concurrent thread that was joined the Suspendible Thread
2062   // Set. If there's ever a cheap way to check this, we should add an
2063   // assert here.
2064 
2065   // Given that this method is called at the end of a Full GC or of a
2066   // concurrent cycle, and those can be nested (i.e., a Full GC can
2067   // interrupt a concurrent cycle), the number of full collections
2068   // completed should be either one (in the case where there was no
2069   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2070   // behind the number of full collections started.
2071 
2072   // This is the case for the inner caller, i.e. a Full GC.
2073   assert(concurrent ||
2074          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2075          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2076          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2077          "is inconsistent with _old_marking_cycles_completed = %u",
2078          _old_marking_cycles_started, _old_marking_cycles_completed);
2079 
2080   // This is the case for the outer caller, i.e. the concurrent cycle.
2081   assert(!concurrent ||
2082          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2083          "for outer caller (concurrent cycle): "
2084          "_old_marking_cycles_started = %u "
2085          "is inconsistent with _old_marking_cycles_completed = %u",
2086          _old_marking_cycles_started, _old_marking_cycles_completed);
2087 
2088   _old_marking_cycles_completed += 1;
2089 
2090   // We need to clear the "in_progress" flag in the CM thread before
2091   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2092   // is set) so that if a waiter requests another System.gc() it doesn't
2093   // incorrectly see that a marking cycle is still in progress.
2094   if (concurrent) {
2095     _cm_thread->set_idle();
2096   }
2097 
2098   // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2099   // for a full GC to finish that their wait is over.
2100   ml.notify_all();
2101 }
2102 
2103 void G1CollectedHeap::collect(GCCause::Cause cause) {
2104   try_collect(cause);
2105 }
2106 
2107 // Return true if (x < y) with allowance for wraparound.
2108 static bool gc_counter_less_than(uint x, uint y) {
2109   return (x - y) > (UINT_MAX/2);
2110 }
2111 
2112 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2113 // Macro so msg printing is format-checked.
2114 #define LOG_COLLECT_CONCURRENTLY(cause, ...)                            \
2115   do {                                                                  \
2116     LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt;                   \
2117     if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) {                     \
2118       ResourceMark rm; /* For thread name. */                           \
2119       LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2120       LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2121                                        Thread::current()->name(),       \
2122                                        GCCause::to_string(cause));      \
2123       LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__);                    \
2124     }                                                                   \
2125   } while (0)
2126 
2127 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2128   LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2129 
2130 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2131                                                uint gc_counter,
2132                                                uint old_marking_started_before) {
2133   assert_heap_not_locked();
2134   assert(should_do_concurrent_full_gc(cause),
2135          "Non-concurrent cause %s", GCCause::to_string(cause));
2136 
2137   for (uint i = 1; true; ++i) {
2138     // Try to schedule an initial-mark evacuation pause that will
2139     // start a concurrent cycle.
2140     LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2141     VM_G1TryInitiateConcMark op(gc_counter,
2142                                 cause,
2143                                 policy()->max_pause_time_ms());
2144     VMThread::execute(&op);
2145 
2146     // Request is trivially finished.
2147     if (cause == GCCause::_g1_periodic_collection) {
2148       LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2149       return op.gc_succeeded();
2150     }
2151 
2152     // If VMOp skipped initiating concurrent marking cycle because
2153     // we're terminating, then we're done.
2154     if (op.terminating()) {
2155       LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2156       return false;
2157     }
2158 
2159     // Lock to get consistent set of values.
2160     uint old_marking_started_after;
2161     uint old_marking_completed_after;
2162     {
2163       MutexLocker ml(Heap_lock);
2164       // Update gc_counter for retrying VMOp if needed. Captured here to be
2165       // consistent with the values we use below for termination tests.  If
2166       // a retry is needed after a possible wait, and another collection
2167       // occurs in the meantime, it will cause our retry to be skipped and
2168       // we'll recheck for termination with updated conditions from that
2169       // more recent collection.  That's what we want, rather than having
2170       // our retry possibly perform an unnecessary collection.
2171       gc_counter = total_collections();
2172       old_marking_started_after = _old_marking_cycles_started;
2173       old_marking_completed_after = _old_marking_cycles_completed;
2174     }
2175 
2176     if (!GCCause::is_user_requested_gc(cause)) {
2177       // For an "automatic" (not user-requested) collection, we just need to
2178       // ensure that progress is made.
2179       //
2180       // Request is finished if any of
2181       // (1) the VMOp successfully performed a GC,
2182       // (2) a concurrent cycle was already in progress,
2183       // (3) a new cycle was started (by this thread or some other), or
2184       // (4) a Full GC was performed.
2185       // Cases (3) and (4) are detected together by a change to
2186       // _old_marking_cycles_started.
2187       //
2188       // Note that (1) does not imply (3).  If we're still in the mixed
2189       // phase of an earlier concurrent collection, the request to make the
2190       // collection an initial-mark won't be honored.  If we don't check for
2191       // both conditions we'll spin doing back-to-back collections.
2192       if (op.gc_succeeded() ||
2193           op.cycle_already_in_progress() ||
2194           (old_marking_started_before != old_marking_started_after)) {
2195         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2196         return true;
2197       }
2198     } else {                    // User-requested GC.
2199       // For a user-requested collection, we want to ensure that a complete
2200       // full collection has been performed before returning, but without
2201       // waiting for more than needed.
2202 
2203       // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2204       // new cycle was started.  That's good, because it's not clear what we
2205       // should do otherwise.  Trying again just does back to back GCs.
2206       // Can't wait for someone else to start a cycle.  And returning fails
2207       // to meet the goal of ensuring a full collection was performed.
2208       assert(!op.gc_succeeded() ||
2209              (old_marking_started_before != old_marking_started_after),
2210              "invariant: succeeded %s, started before %u, started after %u",
2211              BOOL_TO_STR(op.gc_succeeded()),
2212              old_marking_started_before, old_marking_started_after);
2213 
2214       // Request is finished if a full collection (concurrent or stw)
2215       // was started after this request and has completed, e.g.
2216       // started_before < completed_after.
2217       if (gc_counter_less_than(old_marking_started_before,
2218                                old_marking_completed_after)) {
2219         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2220         return true;
2221       }
2222 
2223       if (old_marking_started_after != old_marking_completed_after) {
2224         // If there is an in-progress cycle (possibly started by us), then
2225         // wait for that cycle to complete, e.g.
2226         // while completed_now < started_after.
2227         LOG_COLLECT_CONCURRENTLY(cause, "wait");
2228         MonitorLocker ml(G1OldGCCount_lock);
2229         while (gc_counter_less_than(_old_marking_cycles_completed,
2230                                     old_marking_started_after)) {
2231           ml.wait();
2232         }
2233         // Request is finished if the collection we just waited for was
2234         // started after this request.
2235         if (old_marking_started_before != old_marking_started_after) {
2236           LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2237           return true;
2238         }
2239       }
2240 
2241       // If VMOp was successful then it started a new cycle that the above
2242       // wait &etc should have recognized as finishing this request.  This
2243       // differs from a non-user-request, where gc_succeeded does not imply
2244       // a new cycle was started.
2245       assert(!op.gc_succeeded(), "invariant");
2246 
2247       // If VMOp failed because a cycle was already in progress, it is now
2248       // complete.  But it didn't finish this user-requested GC, so try
2249       // again.
2250       if (op.cycle_already_in_progress()) {
2251         LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2252         continue;
2253       }
2254     }
2255 
2256     // Collection failed and should be retried.
2257     assert(op.transient_failure(), "invariant");
2258 
2259     // If GCLocker is active, wait until clear before retrying.
2260     if (GCLocker::is_active_and_needs_gc()) {
2261       LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2262       GCLocker::stall_until_clear();
2263     }
2264 
2265     LOG_COLLECT_CONCURRENTLY(cause, "retry");
2266   }
2267 }
2268 
2269 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2270   assert_heap_not_locked();
2271 
2272   // Lock to get consistent set of values.
2273   uint gc_count_before;
2274   uint full_gc_count_before;
2275   uint old_marking_started_before;
2276   {
2277     MutexLocker ml(Heap_lock);
2278     gc_count_before = total_collections();
2279     full_gc_count_before = total_full_collections();
2280     old_marking_started_before = _old_marking_cycles_started;
2281   }
2282 
2283   if (should_do_concurrent_full_gc(cause)) {
2284     return try_collect_concurrently(cause,
2285                                     gc_count_before,
2286                                     old_marking_started_before);
2287   } else if (GCLocker::should_discard(cause, gc_count_before)) {
2288     // Indicate failure to be consistent with VMOp failure due to
2289     // another collection slipping in after our gc_count but before
2290     // our request is processed.
2291     return false;
2292   } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2293              DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2294 
2295     // Schedule a standard evacuation pause. We're setting word_size
2296     // to 0 which means that we are not requesting a post-GC allocation.
2297     VM_G1CollectForAllocation op(0,     /* word_size */
2298                                  gc_count_before,
2299                                  cause,
2300                                  policy()->max_pause_time_ms());
2301     VMThread::execute(&op);
2302     return op.gc_succeeded();
2303   } else {
2304     // Schedule a Full GC.
2305     VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2306     VMThread::execute(&op);
2307     return op.gc_succeeded();
2308   }
2309 }
2310 
2311 bool G1CollectedHeap::is_in(const void* p) const {
2312   if (_hrm->reserved().contains(p)) {
2313     // Given that we know that p is in the reserved space,
2314     // heap_region_containing() should successfully
2315     // return the containing region.
2316     HeapRegion* hr = heap_region_containing(p);
2317     return hr->is_in(p);
2318   } else {
2319     return false;
2320   }
2321 }
2322 
2323 #ifdef ASSERT
2324 bool G1CollectedHeap::is_in_exact(const void* p) const {
2325   bool contains = reserved_region().contains(p);
2326   bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2327   if (contains && available) {
2328     return true;
2329   } else {
2330     return false;
2331   }
2332 }
2333 #endif
2334 
2335 // Iteration functions.
2336 
2337 // Iterates an ObjectClosure over all objects within a HeapRegion.
2338 
2339 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2340   ObjectClosure* _cl;
2341 public:
2342   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2343   bool do_heap_region(HeapRegion* r) {
2344     if (!r->is_continues_humongous()) {
2345       r->object_iterate(_cl);
2346     }
2347     return false;
2348   }
2349 };
2350 
2351 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2352   IterateObjectClosureRegionClosure blk(cl);
2353   heap_region_iterate(&blk);
2354 }
2355 
2356 void G1CollectedHeap::keep_alive(oop obj) {
2357   G1BarrierSet::enqueue(obj);
2358 }
2359 
2360 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2361   _hrm->iterate(cl);
2362 }
2363 
2364 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2365                                                                  HeapRegionClaimer *hrclaimer,
2366                                                                  uint worker_id) const {
2367   _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2368 }
2369 
2370 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2371                                                          HeapRegionClaimer *hrclaimer) const {
2372   _hrm->par_iterate(cl, hrclaimer, 0);
2373 }
2374 
2375 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2376   _collection_set.iterate(cl);
2377 }
2378 
2379 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2380   _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2381 }
2382 
2383 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2384   _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2385 }
2386 
2387 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2388   HeapRegion* hr = heap_region_containing(addr);
2389   return hr->block_start(addr);
2390 }
2391 
2392 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2393   HeapRegion* hr = heap_region_containing(addr);
2394   return hr->block_is_obj(addr);
2395 }
2396 
2397 bool G1CollectedHeap::supports_tlab_allocation() const {
2398   return true;
2399 }
2400 
2401 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2402   return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2403 }
2404 
2405 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2406   return _eden.length() * HeapRegion::GrainBytes;
2407 }
2408 
2409 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2410 // must be equal to the humongous object limit.
2411 size_t G1CollectedHeap::max_tlab_size() const {
2412   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2413 }
2414 
2415 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2416   return _allocator->unsafe_max_tlab_alloc();
2417 }
2418 
2419 size_t G1CollectedHeap::max_capacity() const {
2420   return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2421 }
2422 
2423 size_t G1CollectedHeap::max_reserved_capacity() const {
2424   return _hrm->max_length() * HeapRegion::GrainBytes;
2425 }
2426 
2427 jlong G1CollectedHeap::millis_since_last_gc() {
2428   // See the notes in GenCollectedHeap::millis_since_last_gc()
2429   // for more information about the implementation.
2430   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2431                   _policy->collection_pause_end_millis();
2432   if (ret_val < 0) {
2433     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2434       ". returning zero instead.", ret_val);
2435     return 0;
2436   }
2437   return ret_val;
2438 }
2439 
2440 void G1CollectedHeap::deduplicate_string(oop str) {
2441   assert(java_lang_String::is_instance(str), "invariant");
2442 
2443   if (G1StringDedup::is_enabled()) {
2444     G1StringDedup::deduplicate(str);
2445   }
2446 }
2447 
2448 void G1CollectedHeap::prepare_for_verify() {
2449   _verifier->prepare_for_verify();
2450 }
2451 
2452 void G1CollectedHeap::verify(VerifyOption vo) {
2453   _verifier->verify(vo);
2454 }
2455 
2456 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2457   return true;
2458 }
2459 
2460 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2461   return _cm_thread->request_concurrent_phase(phase);
2462 }
2463 
2464 bool G1CollectedHeap::is_heterogeneous_heap() const {
2465   return G1Arguments::is_heterogeneous_heap();
2466 }
2467 
2468 class PrintRegionClosure: public HeapRegionClosure {
2469   outputStream* _st;
2470 public:
2471   PrintRegionClosure(outputStream* st) : _st(st) {}
2472   bool do_heap_region(HeapRegion* r) {
2473     r->print_on(_st);
2474     return false;
2475   }
2476 };
2477 
2478 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2479                                        const HeapRegion* hr,
2480                                        const VerifyOption vo) const {
2481   switch (vo) {
2482   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2483   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2484   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2485   default:                            ShouldNotReachHere();
2486   }
2487   return false; // keep some compilers happy
2488 }
2489 
2490 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2491                                        const VerifyOption vo) const {
2492   switch (vo) {
2493   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2494   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2495   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2496   default:                            ShouldNotReachHere();
2497   }
2498   return false; // keep some compilers happy
2499 }
2500 
2501 void G1CollectedHeap::print_heap_regions() const {
2502   LogTarget(Trace, gc, heap, region) lt;
2503   if (lt.is_enabled()) {
2504     LogStream ls(lt);
2505     print_regions_on(&ls);
2506   }
2507 }
2508 
2509 void G1CollectedHeap::print_on(outputStream* st) const {
2510   st->print(" %-20s", "garbage-first heap");
2511   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2512             capacity()/K, used_unlocked()/K);
2513   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2514             p2i(_hrm->reserved().start()),
2515             p2i(_hrm->reserved().end()));
2516   st->cr();
2517   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2518   uint young_regions = young_regions_count();
2519   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2520             (size_t) young_regions * HeapRegion::GrainBytes / K);
2521   uint survivor_regions = survivor_regions_count();
2522   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2523             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2524   st->cr();
2525   if (_numa->is_enabled()) {
2526     uint num_nodes = _numa->num_active_nodes();
2527     st->print("  remaining free region(s) on each NUMA node: ");
2528     const int* node_ids = _numa->node_ids();
2529     for (uint node_index = 0; node_index < num_nodes; node_index++) {
2530       st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index));
2531     }
2532     st->cr();
2533   }
2534   MetaspaceUtils::print_on(st);
2535 }
2536 
2537 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2538   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2539                "HS=humongous(starts), HC=humongous(continues), "
2540                "CS=collection set, F=free, "
2541                "OA=open archive, CA=closed archive, "
2542                "TAMS=top-at-mark-start (previous, next)");
2543   PrintRegionClosure blk(st);
2544   heap_region_iterate(&blk);
2545 }
2546 
2547 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2548   print_on(st);
2549 
2550   // Print the per-region information.
2551   print_regions_on(st);
2552 }
2553 
2554 void G1CollectedHeap::print_on_error(outputStream* st) const {
2555   this->CollectedHeap::print_on_error(st);
2556 
2557   if (_cm != NULL) {
2558     st->cr();
2559     _cm->print_on_error(st);
2560   }
2561 }
2562 
2563 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2564   workers()->print_worker_threads_on(st);
2565   _cm_thread->print_on(st);
2566   st->cr();
2567   _cm->print_worker_threads_on(st);
2568   _cr->print_threads_on(st);
2569   _young_gen_sampling_thread->print_on(st);
2570   if (G1StringDedup::is_enabled()) {
2571     G1StringDedup::print_worker_threads_on(st);
2572   }
2573 }
2574 
2575 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2576   workers()->threads_do(tc);
2577   tc->do_thread(_cm_thread);
2578   _cm->threads_do(tc);
2579   _cr->threads_do(tc);
2580   tc->do_thread(_young_gen_sampling_thread);
2581   if (G1StringDedup::is_enabled()) {
2582     G1StringDedup::threads_do(tc);
2583   }
2584 }
2585 
2586 void G1CollectedHeap::print_tracing_info() const {
2587   rem_set()->print_summary_info();
2588   concurrent_mark()->print_summary_info();
2589 }
2590 
2591 #ifndef PRODUCT
2592 // Helpful for debugging RSet issues.
2593 
2594 class PrintRSetsClosure : public HeapRegionClosure {
2595 private:
2596   const char* _msg;
2597   size_t _occupied_sum;
2598 
2599 public:
2600   bool do_heap_region(HeapRegion* r) {
2601     HeapRegionRemSet* hrrs = r->rem_set();
2602     size_t occupied = hrrs->occupied();
2603     _occupied_sum += occupied;
2604 
2605     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2606     if (occupied == 0) {
2607       tty->print_cr("  RSet is empty");
2608     } else {
2609       hrrs->print();
2610     }
2611     tty->print_cr("----------");
2612     return false;
2613   }
2614 
2615   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2616     tty->cr();
2617     tty->print_cr("========================================");
2618     tty->print_cr("%s", msg);
2619     tty->cr();
2620   }
2621 
2622   ~PrintRSetsClosure() {
2623     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2624     tty->print_cr("========================================");
2625     tty->cr();
2626   }
2627 };
2628 
2629 void G1CollectedHeap::print_cset_rsets() {
2630   PrintRSetsClosure cl("Printing CSet RSets");
2631   collection_set_iterate_all(&cl);
2632 }
2633 
2634 void G1CollectedHeap::print_all_rsets() {
2635   PrintRSetsClosure cl("Printing All RSets");;
2636   heap_region_iterate(&cl);
2637 }
2638 #endif // PRODUCT
2639 
2640 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2641   return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2642 }
2643 
2644 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2645 
2646   size_t eden_used_bytes = _eden.used_bytes();
2647   size_t survivor_used_bytes = _survivor.used_bytes();
2648   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2649 
2650   size_t eden_capacity_bytes =
2651     (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2652 
2653   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2654   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2655                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2656 }
2657 
2658 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2659   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2660                        stats->unused(), stats->used(), stats->region_end_waste(),
2661                        stats->regions_filled(), stats->direct_allocated(),
2662                        stats->failure_used(), stats->failure_waste());
2663 }
2664 
2665 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2666   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2667   gc_tracer->report_gc_heap_summary(when, heap_summary);
2668 
2669   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2670   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2671 }
2672 
2673 G1CollectedHeap* G1CollectedHeap::heap() {
2674   CollectedHeap* heap = Universe::heap();
2675   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2676   assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2677   return (G1CollectedHeap*)heap;
2678 }
2679 
2680 void G1CollectedHeap::gc_prologue(bool full) {
2681   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2682 
2683   // This summary needs to be printed before incrementing total collections.
2684   rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2685 
2686   // Update common counters.
2687   increment_total_collections(full /* full gc */);
2688   if (full || collector_state()->in_initial_mark_gc()) {
2689     increment_old_marking_cycles_started();
2690   }
2691 
2692   // Fill TLAB's and such
2693   double start = os::elapsedTime();
2694   ensure_parsability(true);
2695   phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2696 }
2697 
2698 void G1CollectedHeap::gc_epilogue(bool full) {
2699   // Update common counters.
2700   if (full) {
2701     // Update the number of full collections that have been completed.
2702     increment_old_marking_cycles_completed(false /* concurrent */);
2703   }
2704 
2705   // We are at the end of the GC. Total collections has already been increased.
2706   rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2707 
2708   // FIXME: what is this about?
2709   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2710   // is set.
2711 #if COMPILER2_OR_JVMCI
2712   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2713 #endif
2714 
2715   double start = os::elapsedTime();
2716   resize_all_tlabs();
2717   phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2718 
2719   MemoryService::track_memory_usage();
2720   // We have just completed a GC. Update the soft reference
2721   // policy with the new heap occupancy
2722   Universe::update_heap_info_at_gc();
2723 
2724   // Print NUMA statistics.
2725   _numa->print_statistics();
2726 }
2727 
2728 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2729   LogTarget(Trace, gc, heap, verify) lt;
2730 
2731   if (lt.is_enabled()) {
2732     LogStream ls(lt);
2733     // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2734     G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2735     heap_region_iterate(&cl);
2736   }
2737 }
2738 
2739 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2740                                                uint gc_count_before,
2741                                                bool* succeeded,
2742                                                GCCause::Cause gc_cause) {
2743   assert_heap_not_locked_and_not_at_safepoint();
2744   VM_G1CollectForAllocation op(word_size,
2745                                gc_count_before,
2746                                gc_cause,
2747                                policy()->max_pause_time_ms());
2748   VMThread::execute(&op);
2749 
2750   HeapWord* result = op.result();
2751   bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2752   assert(result == NULL || ret_succeeded,
2753          "the result should be NULL if the VM did not succeed");
2754   *succeeded = ret_succeeded;
2755 
2756   assert_heap_not_locked();
2757   return result;
2758 }
2759 
2760 void G1CollectedHeap::do_concurrent_mark() {
2761   MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2762   if (!_cm_thread->in_progress()) {
2763     _cm_thread->set_started();
2764     CGC_lock->notify();
2765   }
2766 }
2767 
2768 size_t G1CollectedHeap::pending_card_num() {
2769   struct CountCardsClosure : public ThreadClosure {
2770     size_t _cards;
2771     CountCardsClosure() : _cards(0) {}
2772     virtual void do_thread(Thread* t) {
2773       _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2774     }
2775   } count_from_threads;
2776   Threads::threads_do(&count_from_threads);
2777 
2778   G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2779   return dcqs.num_cards() + count_from_threads._cards;
2780 }
2781 
2782 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2783   // We don't nominate objects with many remembered set entries, on
2784   // the assumption that such objects are likely still live.
2785   HeapRegionRemSet* rem_set = r->rem_set();
2786 
2787   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2788          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2789          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2790 }
2791 
2792 #ifndef PRODUCT
2793 void G1CollectedHeap::verify_region_attr_remset_update() {
2794   class VerifyRegionAttrRemSet : public HeapRegionClosure {
2795   public:
2796     virtual bool do_heap_region(HeapRegion* r) {
2797       G1CollectedHeap* g1h = G1CollectedHeap::heap();
2798       bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2799       assert(r->rem_set()->is_tracked() == needs_remset_update,
2800              "Region %u remset tracking status (%s) different to region attribute (%s)",
2801              r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2802       return false;
2803     }
2804   } cl;
2805   heap_region_iterate(&cl);
2806 }
2807 #endif
2808 
2809 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2810   public:
2811     bool do_heap_region(HeapRegion* hr) {
2812       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2813         hr->verify_rem_set();
2814       }
2815       return false;
2816     }
2817 };
2818 
2819 uint G1CollectedHeap::num_task_queues() const {
2820   return _task_queues->size();
2821 }
2822 
2823 #if TASKQUEUE_STATS
2824 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2825   st->print_raw_cr("GC Task Stats");
2826   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2827   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2828 }
2829 
2830 void G1CollectedHeap::print_taskqueue_stats() const {
2831   if (!log_is_enabled(Trace, gc, task, stats)) {
2832     return;
2833   }
2834   Log(gc, task, stats) log;
2835   ResourceMark rm;
2836   LogStream ls(log.trace());
2837   outputStream* st = &ls;
2838 
2839   print_taskqueue_stats_hdr(st);
2840 
2841   TaskQueueStats totals;
2842   const uint n = num_task_queues();
2843   for (uint i = 0; i < n; ++i) {
2844     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2845     totals += task_queue(i)->stats;
2846   }
2847   st->print_raw("tot "); totals.print(st); st->cr();
2848 
2849   DEBUG_ONLY(totals.verify());
2850 }
2851 
2852 void G1CollectedHeap::reset_taskqueue_stats() {
2853   const uint n = num_task_queues();
2854   for (uint i = 0; i < n; ++i) {
2855     task_queue(i)->stats.reset();
2856   }
2857 }
2858 #endif // TASKQUEUE_STATS
2859 
2860 void G1CollectedHeap::wait_for_root_region_scanning() {
2861   double scan_wait_start = os::elapsedTime();
2862   // We have to wait until the CM threads finish scanning the
2863   // root regions as it's the only way to ensure that all the
2864   // objects on them have been correctly scanned before we start
2865   // moving them during the GC.
2866   bool waited = _cm->root_regions()->wait_until_scan_finished();
2867   double wait_time_ms = 0.0;
2868   if (waited) {
2869     double scan_wait_end = os::elapsedTime();
2870     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2871   }
2872   phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2873 }
2874 
2875 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2876 private:
2877   G1HRPrinter* _hr_printer;
2878 public:
2879   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2880 
2881   virtual bool do_heap_region(HeapRegion* r) {
2882     _hr_printer->cset(r);
2883     return false;
2884   }
2885 };
2886 
2887 void G1CollectedHeap::start_new_collection_set() {
2888   double start = os::elapsedTime();
2889 
2890   collection_set()->start_incremental_building();
2891 
2892   clear_region_attr();
2893 
2894   guarantee(_eden.length() == 0, "eden should have been cleared");
2895   policy()->transfer_survivors_to_cset(survivor());
2896 
2897   // We redo the verification but now wrt to the new CSet which
2898   // has just got initialized after the previous CSet was freed.
2899   _cm->verify_no_collection_set_oops();
2900 
2901   phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2902 }
2903 
2904 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2905 
2906   _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2907   evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2908                                             collection_set()->optional_region_length());
2909 
2910   _cm->verify_no_collection_set_oops();
2911 
2912   if (_hr_printer.is_active()) {
2913     G1PrintCollectionSetClosure cl(&_hr_printer);
2914     _collection_set.iterate(&cl);
2915     _collection_set.iterate_optional(&cl);
2916   }
2917 }
2918 
2919 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2920   if (collector_state()->in_initial_mark_gc()) {
2921     return G1HeapVerifier::G1VerifyConcurrentStart;
2922   } else if (collector_state()->in_young_only_phase()) {
2923     return G1HeapVerifier::G1VerifyYoungNormal;
2924   } else {
2925     return G1HeapVerifier::G1VerifyMixed;
2926   }
2927 }
2928 
2929 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2930   if (VerifyRememberedSets) {
2931     log_info(gc, verify)("[Verifying RemSets before GC]");
2932     VerifyRegionRemSetClosure v_cl;
2933     heap_region_iterate(&v_cl);
2934   }
2935   _verifier->verify_before_gc(type);
2936   _verifier->check_bitmaps("GC Start");
2937   verify_numa_regions("GC Start");
2938 }
2939 
2940 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2941   if (VerifyRememberedSets) {
2942     log_info(gc, verify)("[Verifying RemSets after GC]");
2943     VerifyRegionRemSetClosure v_cl;
2944     heap_region_iterate(&v_cl);
2945   }
2946   _verifier->verify_after_gc(type);
2947   _verifier->check_bitmaps("GC End");
2948   verify_numa_regions("GC End");
2949 }
2950 
2951 void G1CollectedHeap::expand_heap_after_young_collection(){
2952   size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2953   if (expand_bytes > 0) {
2954     // No need for an ergo logging here,
2955     // expansion_amount() does this when it returns a value > 0.
2956     double expand_ms;
2957     if (!expand(expand_bytes, _workers, &expand_ms)) {
2958       // We failed to expand the heap. Cannot do anything about it.
2959     }
2960     phase_times()->record_expand_heap_time(expand_ms);
2961   }
2962 }
2963 
2964 const char* G1CollectedHeap::young_gc_name() const {
2965   if (collector_state()->in_initial_mark_gc()) {
2966     return "Pause Young (Concurrent Start)";
2967   } else if (collector_state()->in_young_only_phase()) {
2968     if (collector_state()->in_young_gc_before_mixed()) {
2969       return "Pause Young (Prepare Mixed)";
2970     } else {
2971       return "Pause Young (Normal)";
2972     }
2973   } else {
2974     return "Pause Young (Mixed)";
2975   }
2976 }
2977 
2978 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2979   assert_at_safepoint_on_vm_thread();
2980   guarantee(!is_gc_active(), "collection is not reentrant");
2981 
2982   if (GCLocker::check_active_before_gc()) {
2983     return false;
2984   }
2985 
2986   do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2987   if (should_upgrade_to_full_gc(gc_cause())) {
2988     log_info(gc, ergo)("Attempting maximally compacting collection");
2989     bool result = do_full_collection(false /* explicit gc */,
2990                                      true /* clear_all_soft_refs */);
2991     // do_full_collection only fails if blocked by GC locker, but
2992     // we've already checked for that above.
2993     assert(result, "invariant");
2994   }
2995   return true;
2996 }
2997 
2998 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2999   GCIdMark gc_id_mark;
3000 
3001   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3002   ResourceMark rm;
3003 
3004   policy()->note_gc_start();
3005 
3006   _gc_timer_stw->register_gc_start();
3007   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3008 
3009   wait_for_root_region_scanning();
3010 
3011   print_heap_before_gc();
3012   print_heap_regions();
3013   trace_heap_before_gc(_gc_tracer_stw);
3014 
3015   _verifier->verify_region_sets_optional();
3016   _verifier->verify_dirty_young_regions();
3017 
3018   // We should not be doing initial mark unless the conc mark thread is running
3019   if (!_cm_thread->should_terminate()) {
3020     // This call will decide whether this pause is an initial-mark
3021     // pause. If it is, in_initial_mark_gc() will return true
3022     // for the duration of this pause.
3023     policy()->decide_on_conc_mark_initiation();
3024   }
3025 
3026   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3027   assert(!collector_state()->in_initial_mark_gc() ||
3028          collector_state()->in_young_only_phase(), "sanity");
3029   // We also do not allow mixed GCs during marking.
3030   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3031 
3032   // Record whether this pause is an initial mark. When the current
3033   // thread has completed its logging output and it's safe to signal
3034   // the CM thread, the flag's value in the policy has been reset.
3035   bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3036   if (should_start_conc_mark) {
3037     _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3038   }
3039 
3040   // Inner scope for scope based logging, timers, and stats collection
3041   {
3042     G1EvacuationInfo evacuation_info;
3043 
3044     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3045 
3046     GCTraceCPUTime tcpu;
3047 
3048     GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3049 
3050     uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3051                                                             workers()->active_workers(),
3052                                                             Threads::number_of_non_daemon_threads());
3053     active_workers = workers()->update_active_workers(active_workers);
3054     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3055 
3056     G1MonitoringScope ms(g1mm(),
3057                          false /* full_gc */,
3058                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3059 
3060     G1HeapTransition heap_transition(this);
3061 
3062     {
3063       IsGCActiveMark x;
3064 
3065       gc_prologue(false);
3066 
3067       G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3068       verify_before_young_collection(verify_type);
3069 
3070       {
3071         // The elapsed time induced by the start time below deliberately elides
3072         // the possible verification above.
3073         double sample_start_time_sec = os::elapsedTime();
3074 
3075         // Please see comment in g1CollectedHeap.hpp and
3076         // G1CollectedHeap::ref_processing_init() to see how
3077         // reference processing currently works in G1.
3078         _ref_processor_stw->enable_discovery();
3079 
3080         // We want to temporarily turn off discovery by the
3081         // CM ref processor, if necessary, and turn it back on
3082         // on again later if we do. Using a scoped
3083         // NoRefDiscovery object will do this.
3084         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3085 
3086         policy()->record_collection_pause_start(sample_start_time_sec);
3087 
3088         // Forget the current allocation region (we might even choose it to be part
3089         // of the collection set!).
3090         _allocator->release_mutator_alloc_regions();
3091 
3092         calculate_collection_set(evacuation_info, target_pause_time_ms);
3093 
3094         G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3095         G1ParScanThreadStateSet per_thread_states(this,
3096                                                   &rdcqs,
3097                                                   workers()->active_workers(),
3098                                                   collection_set()->young_region_length(),
3099                                                   collection_set()->optional_region_length());
3100         pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3101 
3102         // Actually do the work...
3103         evacuate_initial_collection_set(&per_thread_states);
3104 
3105         if (_collection_set.optional_region_length() != 0) {
3106           evacuate_optional_collection_set(&per_thread_states);
3107         }
3108         post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3109 
3110         start_new_collection_set();
3111 
3112         _survivor_evac_stats.adjust_desired_plab_sz();
3113         _old_evac_stats.adjust_desired_plab_sz();
3114 
3115         if (should_start_conc_mark) {
3116           // We have to do this before we notify the CM threads that
3117           // they can start working to make sure that all the
3118           // appropriate initialization is done on the CM object.
3119           concurrent_mark()->post_initial_mark();
3120           // Note that we don't actually trigger the CM thread at
3121           // this point. We do that later when we're sure that
3122           // the current thread has completed its logging output.
3123         }
3124 
3125         allocate_dummy_regions();
3126 
3127         _allocator->init_mutator_alloc_regions();
3128 
3129         expand_heap_after_young_collection();
3130 
3131         double sample_end_time_sec = os::elapsedTime();
3132         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3133         policy()->record_collection_pause_end(pause_time_ms);
3134       }
3135 
3136       verify_after_young_collection(verify_type);
3137 
3138       gc_epilogue(false);
3139     }
3140 
3141     // Print the remainder of the GC log output.
3142     if (evacuation_failed()) {
3143       log_info(gc)("To-space exhausted");
3144     }
3145 
3146     policy()->print_phases();
3147     heap_transition.print();
3148 
3149     _hrm->verify_optional();
3150     _verifier->verify_region_sets_optional();
3151 
3152     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3153     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3154 
3155     print_heap_after_gc();
3156     print_heap_regions();
3157     trace_heap_after_gc(_gc_tracer_stw);
3158 
3159     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3160     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3161     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3162     // before any GC notifications are raised.
3163     g1mm()->update_sizes();
3164 
3165     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3166     _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3167     _gc_timer_stw->register_gc_end();
3168     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3169   }
3170   // It should now be safe to tell the concurrent mark thread to start
3171   // without its logging output interfering with the logging output
3172   // that came from the pause.
3173 
3174   if (should_start_conc_mark) {
3175     // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3176     // thread(s) could be running concurrently with us. Make sure that anything
3177     // after this point does not assume that we are the only GC thread running.
3178     // Note: of course, the actual marking work will not start until the safepoint
3179     // itself is released in SuspendibleThreadSet::desynchronize().
3180     do_concurrent_mark();
3181   }
3182 }
3183 
3184 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3185   G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3186   workers()->run_task(&rsfp_task);
3187 }
3188 
3189 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3190   double remove_self_forwards_start = os::elapsedTime();
3191 
3192   remove_self_forwarding_pointers(rdcqs);
3193   _preserved_marks_set.restore(workers());
3194 
3195   phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3196 }
3197 
3198 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3199   if (!_evacuation_failed) {
3200     _evacuation_failed = true;
3201   }
3202 
3203   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3204   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3205 }
3206 
3207 bool G1ParEvacuateFollowersClosure::offer_termination() {
3208   EventGCPhaseParallel event;
3209   G1ParScanThreadState* const pss = par_scan_state();
3210   start_term_time();
3211   const bool res = terminator()->offer_termination();
3212   end_term_time();
3213   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3214   return res;
3215 }
3216 
3217 void G1ParEvacuateFollowersClosure::do_void() {
3218   EventGCPhaseParallel event;
3219   G1ParScanThreadState* const pss = par_scan_state();
3220   pss->trim_queue();
3221   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3222   do {
3223     EventGCPhaseParallel event;
3224     pss->steal_and_trim_queue(queues());
3225     event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3226   } while (!offer_termination());
3227 }
3228 
3229 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3230                                         bool class_unloading_occurred) {
3231   uint num_workers = workers()->active_workers();
3232   G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3233   workers()->run_task(&unlink_task);
3234 }
3235 
3236 // Clean string dedup data structures.
3237 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3238 // record the durations of the phases. Hence the almost-copy.
3239 class G1StringDedupCleaningTask : public AbstractGangTask {
3240   BoolObjectClosure* _is_alive;
3241   OopClosure* _keep_alive;
3242   G1GCPhaseTimes* _phase_times;
3243 
3244 public:
3245   G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3246                             OopClosure* keep_alive,
3247                             G1GCPhaseTimes* phase_times) :
3248     AbstractGangTask("Partial Cleaning Task"),
3249     _is_alive(is_alive),
3250     _keep_alive(keep_alive),
3251     _phase_times(phase_times)
3252   {
3253     assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3254     StringDedup::gc_prologue(true);
3255   }
3256 
3257   ~G1StringDedupCleaningTask() {
3258     StringDedup::gc_epilogue();
3259   }
3260 
3261   void work(uint worker_id) {
3262     StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3263     {
3264       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3265       StringDedupQueue::unlink_or_oops_do(&cl);
3266     }
3267     {
3268       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3269       StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3270     }
3271   }
3272 };
3273 
3274 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3275                                             OopClosure* keep_alive,
3276                                             G1GCPhaseTimes* phase_times) {
3277   G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3278   workers()->run_task(&cl);
3279 }
3280 
3281 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3282  private:
3283   G1RedirtyCardsQueueSet* _qset;
3284   G1CollectedHeap* _g1h;
3285   BufferNode* volatile _nodes;
3286 
3287   void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3288     size_t buffer_size = _qset->buffer_size();
3289     BufferNode* next = Atomic::load(&_nodes);
3290     while (next != NULL) {
3291       BufferNode* node = next;
3292       next = Atomic::cmpxchg(&_nodes, node, node->next());
3293       if (next == node) {
3294         cl->apply_to_buffer(node, buffer_size, worker_id);
3295         next = node->next();
3296       }
3297     }
3298   }
3299 
3300  public:
3301   G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3302     AbstractGangTask("Redirty Cards"),
3303     _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3304 
3305   virtual void work(uint worker_id) {
3306     G1GCPhaseTimes* p = _g1h->phase_times();
3307     G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3308 
3309     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3310     par_apply(&cl, worker_id);
3311 
3312     p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3313   }
3314 };
3315 
3316 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3317   double redirty_logged_cards_start = os::elapsedTime();
3318 
3319   G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3320   workers()->run_task(&redirty_task);
3321 
3322   G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3323   dcq.merge_bufferlists(rdcqs);
3324 
3325   phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3326 }
3327 
3328 // Weak Reference Processing support
3329 
3330 bool G1STWIsAliveClosure::do_object_b(oop p) {
3331   // An object is reachable if it is outside the collection set,
3332   // or is inside and copied.
3333   return !_g1h->is_in_cset(p) || p->is_forwarded();
3334 }
3335 
3336 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3337   assert(obj != NULL, "must not be NULL");
3338   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3339   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3340   // may falsely indicate that this is not the case here: however the collection set only
3341   // contains old regions when concurrent mark is not running.
3342   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3343 }
3344 
3345 // Non Copying Keep Alive closure
3346 class G1KeepAliveClosure: public OopClosure {
3347   G1CollectedHeap*_g1h;
3348 public:
3349   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3350   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3351   void do_oop(oop* p) {
3352     oop obj = *p;
3353     assert(obj != NULL, "the caller should have filtered out NULL values");
3354 
3355     const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3356     if (!region_attr.is_in_cset_or_humongous()) {
3357       return;
3358     }
3359     if (region_attr.is_in_cset()) {
3360       assert( obj->is_forwarded(), "invariant" );
3361       *p = obj->forwardee();
3362     } else {
3363       assert(!obj->is_forwarded(), "invariant" );
3364       assert(region_attr.is_humongous(),
3365              "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3366      _g1h->set_humongous_is_live(obj);
3367     }
3368   }
3369 };
3370 
3371 // Copying Keep Alive closure - can be called from both
3372 // serial and parallel code as long as different worker
3373 // threads utilize different G1ParScanThreadState instances
3374 // and different queues.
3375 
3376 class G1CopyingKeepAliveClosure: public OopClosure {
3377   G1CollectedHeap*         _g1h;
3378   G1ParScanThreadState*    _par_scan_state;
3379 
3380 public:
3381   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3382                             G1ParScanThreadState* pss):
3383     _g1h(g1h),
3384     _par_scan_state(pss)
3385   {}
3386 
3387   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3388   virtual void do_oop(      oop* p) { do_oop_work(p); }
3389 
3390   template <class T> void do_oop_work(T* p) {
3391     oop obj = RawAccess<>::oop_load(p);
3392 
3393     if (_g1h->is_in_cset_or_humongous(obj)) {
3394       // If the referent object has been forwarded (either copied
3395       // to a new location or to itself in the event of an
3396       // evacuation failure) then we need to update the reference
3397       // field and, if both reference and referent are in the G1
3398       // heap, update the RSet for the referent.
3399       //
3400       // If the referent has not been forwarded then we have to keep
3401       // it alive by policy. Therefore we have copy the referent.
3402       //
3403       // When the queue is drained (after each phase of reference processing)
3404       // the object and it's followers will be copied, the reference field set
3405       // to point to the new location, and the RSet updated.
3406       _par_scan_state->push_on_queue(p);
3407     }
3408   }
3409 };
3410 
3411 // Serial drain queue closure. Called as the 'complete_gc'
3412 // closure for each discovered list in some of the
3413 // reference processing phases.
3414 
3415 class G1STWDrainQueueClosure: public VoidClosure {
3416 protected:
3417   G1CollectedHeap* _g1h;
3418   G1ParScanThreadState* _par_scan_state;
3419 
3420   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3421 
3422 public:
3423   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3424     _g1h(g1h),
3425     _par_scan_state(pss)
3426   { }
3427 
3428   void do_void() {
3429     G1ParScanThreadState* const pss = par_scan_state();
3430     pss->trim_queue();
3431   }
3432 };
3433 
3434 // Parallel Reference Processing closures
3435 
3436 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3437 // processing during G1 evacuation pauses.
3438 
3439 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3440 private:
3441   G1CollectedHeap*          _g1h;
3442   G1ParScanThreadStateSet*  _pss;
3443   RefToScanQueueSet*        _queues;
3444   WorkGang*                 _workers;
3445 
3446 public:
3447   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3448                            G1ParScanThreadStateSet* per_thread_states,
3449                            WorkGang* workers,
3450                            RefToScanQueueSet *task_queues) :
3451     _g1h(g1h),
3452     _pss(per_thread_states),
3453     _queues(task_queues),
3454     _workers(workers)
3455   {
3456     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3457   }
3458 
3459   // Executes the given task using concurrent marking worker threads.
3460   virtual void execute(ProcessTask& task, uint ergo_workers);
3461 };
3462 
3463 // Gang task for possibly parallel reference processing
3464 
3465 class G1STWRefProcTaskProxy: public AbstractGangTask {
3466   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3467   ProcessTask&     _proc_task;
3468   G1CollectedHeap* _g1h;
3469   G1ParScanThreadStateSet* _pss;
3470   RefToScanQueueSet* _task_queues;
3471   TaskTerminator* _terminator;
3472 
3473 public:
3474   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3475                         G1CollectedHeap* g1h,
3476                         G1ParScanThreadStateSet* per_thread_states,
3477                         RefToScanQueueSet *task_queues,
3478                         TaskTerminator* terminator) :
3479     AbstractGangTask("Process reference objects in parallel"),
3480     _proc_task(proc_task),
3481     _g1h(g1h),
3482     _pss(per_thread_states),
3483     _task_queues(task_queues),
3484     _terminator(terminator)
3485   {}
3486 
3487   virtual void work(uint worker_id) {
3488     // The reference processing task executed by a single worker.
3489     ResourceMark rm;
3490     HandleMark   hm;
3491 
3492     G1STWIsAliveClosure is_alive(_g1h);
3493 
3494     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3495     pss->set_ref_discoverer(NULL);
3496 
3497     // Keep alive closure.
3498     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3499 
3500     // Complete GC closure
3501     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3502 
3503     // Call the reference processing task's work routine.
3504     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3505 
3506     // Note we cannot assert that the refs array is empty here as not all
3507     // of the processing tasks (specifically phase2 - pp2_work) execute
3508     // the complete_gc closure (which ordinarily would drain the queue) so
3509     // the queue may not be empty.
3510   }
3511 };
3512 
3513 // Driver routine for parallel reference processing.
3514 // Creates an instance of the ref processing gang
3515 // task and has the worker threads execute it.
3516 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3517   assert(_workers != NULL, "Need parallel worker threads.");
3518 
3519   assert(_workers->active_workers() >= ergo_workers,
3520          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3521          ergo_workers, _workers->active_workers());
3522   TaskTerminator terminator(ergo_workers, _queues);
3523   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3524 
3525   _workers->run_task(&proc_task_proxy, ergo_workers);
3526 }
3527 
3528 // End of weak reference support closures
3529 
3530 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3531   double ref_proc_start = os::elapsedTime();
3532 
3533   ReferenceProcessor* rp = _ref_processor_stw;
3534   assert(rp->discovery_enabled(), "should have been enabled");
3535 
3536   // Closure to test whether a referent is alive.
3537   G1STWIsAliveClosure is_alive(this);
3538 
3539   // Even when parallel reference processing is enabled, the processing
3540   // of JNI refs is serial and performed serially by the current thread
3541   // rather than by a worker. The following PSS will be used for processing
3542   // JNI refs.
3543 
3544   // Use only a single queue for this PSS.
3545   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3546   pss->set_ref_discoverer(NULL);
3547   assert(pss->queue_is_empty(), "pre-condition");
3548 
3549   // Keep alive closure.
3550   G1CopyingKeepAliveClosure keep_alive(this, pss);
3551 
3552   // Serial Complete GC closure
3553   G1STWDrainQueueClosure drain_queue(this, pss);
3554 
3555   // Setup the soft refs policy...
3556   rp->setup_policy(false);
3557 
3558   ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3559 
3560   ReferenceProcessorStats stats;
3561   if (!rp->processing_is_mt()) {
3562     // Serial reference processing...
3563     stats = rp->process_discovered_references(&is_alive,
3564                                               &keep_alive,
3565                                               &drain_queue,
3566                                               NULL,
3567                                               pt);
3568   } else {
3569     uint no_of_gc_workers = workers()->active_workers();
3570 
3571     // Parallel reference processing
3572     assert(no_of_gc_workers <= rp->max_num_queues(),
3573            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3574            no_of_gc_workers,  rp->max_num_queues());
3575 
3576     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3577     stats = rp->process_discovered_references(&is_alive,
3578                                               &keep_alive,
3579                                               &drain_queue,
3580                                               &par_task_executor,
3581                                               pt);
3582   }
3583 
3584   _gc_tracer_stw->report_gc_reference_stats(stats);
3585 
3586   // We have completed copying any necessary live referent objects.
3587   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3588 
3589   make_pending_list_reachable();
3590 
3591   assert(!rp->discovery_enabled(), "Postcondition");
3592   rp->verify_no_references_recorded();
3593 
3594   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3595   phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3596 }
3597 
3598 void G1CollectedHeap::make_pending_list_reachable() {
3599   if (collector_state()->in_initial_mark_gc()) {
3600     oop pll_head = Universe::reference_pending_list();
3601     if (pll_head != NULL) {
3602       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3603       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3604     }
3605   }
3606 }
3607 
3608 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3609   Ticks start = Ticks::now();
3610   per_thread_states->flush();
3611   phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3612 }
3613 
3614 class G1PrepareEvacuationTask : public AbstractGangTask {
3615   class G1PrepareRegionsClosure : public HeapRegionClosure {
3616     G1CollectedHeap* _g1h;
3617     G1PrepareEvacuationTask* _parent_task;
3618     size_t _worker_humongous_total;
3619     size_t _worker_humongous_candidates;
3620 
3621     bool humongous_region_is_candidate(HeapRegion* region) const {
3622       assert(region->is_starts_humongous(), "Must start a humongous object");
3623 
3624       oop obj = oop(region->bottom());
3625 
3626       // Dead objects cannot be eager reclaim candidates. Due to class
3627       // unloading it is unsafe to query their classes so we return early.
3628       if (_g1h->is_obj_dead(obj, region)) {
3629         return false;
3630       }
3631 
3632       // If we do not have a complete remembered set for the region, then we can
3633       // not be sure that we have all references to it.
3634       if (!region->rem_set()->is_complete()) {
3635         return false;
3636       }
3637       // Candidate selection must satisfy the following constraints
3638       // while concurrent marking is in progress:
3639       //
3640       // * In order to maintain SATB invariants, an object must not be
3641       // reclaimed if it was allocated before the start of marking and
3642       // has not had its references scanned.  Such an object must have
3643       // its references (including type metadata) scanned to ensure no
3644       // live objects are missed by the marking process.  Objects
3645       // allocated after the start of concurrent marking don't need to
3646       // be scanned.
3647       //
3648       // * An object must not be reclaimed if it is on the concurrent
3649       // mark stack.  Objects allocated after the start of concurrent
3650       // marking are never pushed on the mark stack.
3651       //
3652       // Nominating only objects allocated after the start of concurrent
3653       // marking is sufficient to meet both constraints.  This may miss
3654       // some objects that satisfy the constraints, but the marking data
3655       // structures don't support efficiently performing the needed
3656       // additional tests or scrubbing of the mark stack.
3657       //
3658       // However, we presently only nominate is_typeArray() objects.
3659       // A humongous object containing references induces remembered
3660       // set entries on other regions.  In order to reclaim such an
3661       // object, those remembered sets would need to be cleaned up.
3662       //
3663       // We also treat is_typeArray() objects specially, allowing them
3664       // to be reclaimed even if allocated before the start of
3665       // concurrent mark.  For this we rely on mark stack insertion to
3666       // exclude is_typeArray() objects, preventing reclaiming an object
3667       // that is in the mark stack.  We also rely on the metadata for
3668       // such objects to be built-in and so ensured to be kept live.
3669       // Frequent allocation and drop of large binary blobs is an
3670       // important use case for eager reclaim, and this special handling
3671       // may reduce needed headroom.
3672 
3673       return obj->is_typeArray() &&
3674              _g1h->is_potential_eager_reclaim_candidate(region);
3675     }
3676 
3677   public:
3678     G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3679       _g1h(g1h),
3680       _parent_task(parent_task),
3681       _worker_humongous_total(0),
3682       _worker_humongous_candidates(0) { }
3683 
3684     ~G1PrepareRegionsClosure() {
3685       _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3686       _parent_task->add_humongous_total(_worker_humongous_total);
3687     }
3688 
3689     virtual bool do_heap_region(HeapRegion* hr) {
3690       // First prepare the region for scanning
3691       _g1h->rem_set()->prepare_region_for_scan(hr);
3692 
3693       // Now check if region is a humongous candidate
3694       if (!hr->is_starts_humongous()) {
3695         _g1h->register_region_with_region_attr(hr);
3696         return false;
3697       }
3698 
3699       uint index = hr->hrm_index();
3700       if (humongous_region_is_candidate(hr)) {
3701         _g1h->set_humongous_reclaim_candidate(index, true);
3702         _g1h->register_humongous_region_with_region_attr(index);
3703         _worker_humongous_candidates++;
3704         // We will later handle the remembered sets of these regions.
3705       } else {
3706         _g1h->set_humongous_reclaim_candidate(index, false);
3707         _g1h->register_region_with_region_attr(hr);
3708       }
3709       _worker_humongous_total++;
3710 
3711       return false;
3712     }
3713   };
3714 
3715   G1CollectedHeap* _g1h;
3716   HeapRegionClaimer _claimer;
3717   volatile size_t _humongous_total;
3718   volatile size_t _humongous_candidates;
3719 public:
3720   G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3721     AbstractGangTask("Prepare Evacuation"),
3722     _g1h(g1h),
3723     _claimer(_g1h->workers()->active_workers()),
3724     _humongous_total(0),
3725     _humongous_candidates(0) { }
3726 
3727   ~G1PrepareEvacuationTask() {
3728     _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3729   }
3730 
3731   void work(uint worker_id) {
3732     G1PrepareRegionsClosure cl(_g1h, this);
3733     _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3734   }
3735 
3736   void add_humongous_candidates(size_t candidates) {
3737     Atomic::add(&_humongous_candidates, candidates);
3738   }
3739 
3740   void add_humongous_total(size_t total) {
3741     Atomic::add(&_humongous_total, total);
3742   }
3743 
3744   size_t humongous_candidates() {
3745     return _humongous_candidates;
3746   }
3747 
3748   size_t humongous_total() {
3749     return _humongous_total;
3750   }
3751 };
3752 
3753 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3754   _bytes_used_during_gc = 0;
3755 
3756   _expand_heap_after_alloc_failure = true;
3757   _evacuation_failed = false;
3758 
3759   // Disable the hot card cache.
3760   _hot_card_cache->reset_hot_cache_claimed_index();
3761   _hot_card_cache->set_use_cache(false);
3762 
3763   // Initialize the GC alloc regions.
3764   _allocator->init_gc_alloc_regions(evacuation_info);
3765 
3766   {
3767     Ticks start = Ticks::now();
3768     rem_set()->prepare_for_scan_heap_roots();
3769     phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3770   }
3771 
3772   {
3773     G1PrepareEvacuationTask g1_prep_task(this);
3774     Tickspan task_time = run_task(&g1_prep_task);
3775 
3776     phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3777                                            g1_prep_task.humongous_total(),
3778                                            g1_prep_task.humongous_candidates());
3779   }
3780 
3781   assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3782   _preserved_marks_set.assert_empty();
3783 
3784 #if COMPILER2_OR_JVMCI
3785   DerivedPointerTable::clear();
3786 #endif
3787 
3788   // InitialMark needs claim bits to keep track of the marked-through CLDs.
3789   if (collector_state()->in_initial_mark_gc()) {
3790     concurrent_mark()->pre_initial_mark();
3791 
3792     double start_clear_claimed_marks = os::elapsedTime();
3793 
3794     ClassLoaderDataGraph::clear_claimed_marks();
3795 
3796     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3797     phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3798   }
3799 
3800   // Should G1EvacuationFailureALot be in effect for this GC?
3801   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3802 }
3803 
3804 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3805 protected:
3806   G1CollectedHeap* _g1h;
3807   G1ParScanThreadStateSet* _per_thread_states;
3808   RefToScanQueueSet* _task_queues;
3809   TaskTerminator _terminator;
3810   uint _num_workers;
3811 
3812   void evacuate_live_objects(G1ParScanThreadState* pss,
3813                              uint worker_id,
3814                              G1GCPhaseTimes::GCParPhases objcopy_phase,
3815                              G1GCPhaseTimes::GCParPhases termination_phase) {
3816     G1GCPhaseTimes* p = _g1h->phase_times();
3817 
3818     Ticks start = Ticks::now();
3819     G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3820     cl.do_void();
3821 
3822     assert(pss->queue_is_empty(), "should be empty");
3823 
3824     Tickspan evac_time = (Ticks::now() - start);
3825     p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3826 
3827     if (termination_phase == G1GCPhaseTimes::Termination) {
3828       p->record_time_secs(termination_phase, worker_id, cl.term_time());
3829       p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3830     } else {
3831       p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3832       p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3833     }
3834     assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3835   }
3836 
3837   virtual void start_work(uint worker_id) { }
3838 
3839   virtual void end_work(uint worker_id) { }
3840 
3841   virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3842 
3843   virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3844 
3845 public:
3846   G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3847     AbstractGangTask(name),
3848     _g1h(G1CollectedHeap::heap()),
3849     _per_thread_states(per_thread_states),
3850     _task_queues(task_queues),
3851     _terminator(num_workers, _task_queues),
3852     _num_workers(num_workers)
3853   { }
3854 
3855   void work(uint worker_id) {
3856     start_work(worker_id);
3857 
3858     {
3859       ResourceMark rm;
3860       HandleMark   hm;
3861 
3862       G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3863       pss->set_ref_discoverer(_g1h->ref_processor_stw());
3864 
3865       scan_roots(pss, worker_id);
3866       evacuate_live_objects(pss, worker_id);
3867     }
3868 
3869     end_work(worker_id);
3870   }
3871 };
3872 
3873 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3874   G1RootProcessor* _root_processor;
3875 
3876   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3877     _root_processor->evacuate_roots(pss, worker_id);
3878     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3879     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3880   }
3881 
3882   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3883     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3884   }
3885 
3886   void start_work(uint worker_id) {
3887     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3888   }
3889 
3890   void end_work(uint worker_id) {
3891     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3892   }
3893 
3894 public:
3895   G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3896                         G1ParScanThreadStateSet* per_thread_states,
3897                         RefToScanQueueSet* task_queues,
3898                         G1RootProcessor* root_processor,
3899                         uint num_workers) :
3900     G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3901     _root_processor(root_processor)
3902   { }
3903 };
3904 
3905 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3906   G1GCPhaseTimes* p = phase_times();
3907 
3908   {
3909     Ticks start = Ticks::now();
3910     rem_set()->merge_heap_roots(true /* initial_evacuation */);
3911     p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3912   }
3913 
3914   Tickspan task_time;
3915   const uint num_workers = workers()->active_workers();
3916 
3917   Ticks start_processing = Ticks::now();
3918   {
3919     G1RootProcessor root_processor(this, num_workers);
3920     G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3921     task_time = run_task(&g1_par_task);
3922     // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3923     // To extract its code root fixup time we measure total time of this scope and
3924     // subtract from the time the WorkGang task took.
3925   }
3926   Tickspan total_processing = Ticks::now() - start_processing;
3927 
3928   p->record_initial_evac_time(task_time.seconds() * 1000.0);
3929   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3930 }
3931 
3932 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3933 
3934   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3935     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3936     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3937   }
3938 
3939   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3940     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3941   }
3942 
3943 public:
3944   G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3945                                 RefToScanQueueSet* queues,
3946                                 uint num_workers) :
3947     G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3948   }
3949 };
3950 
3951 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3952   class G1MarkScope : public MarkScope { };
3953 
3954   Tickspan task_time;
3955 
3956   Ticks start_processing = Ticks::now();
3957   {
3958     G1MarkScope code_mark_scope;
3959     G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3960     task_time = run_task(&task);
3961     // See comment in evacuate_collection_set() for the reason of the scope.
3962   }
3963   Tickspan total_processing = Ticks::now() - start_processing;
3964 
3965   G1GCPhaseTimes* p = phase_times();
3966   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3967 }
3968 
3969 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3970   const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3971 
3972   while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3973 
3974     double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3975     double time_left_ms = MaxGCPauseMillis - time_used_ms;
3976 
3977     if (time_left_ms < 0 ||
3978         !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3979       log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3980                                 _collection_set.optional_region_length(), time_left_ms);
3981       break;
3982     }
3983 
3984     {
3985       Ticks start = Ticks::now();
3986       rem_set()->merge_heap_roots(false /* initial_evacuation */);
3987       phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3988     }
3989 
3990     {
3991       Ticks start = Ticks::now();
3992       evacuate_next_optional_regions(per_thread_states);
3993       phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3994     }
3995   }
3996 
3997   _collection_set.abandon_optional_collection_set(per_thread_states);
3998 }
3999 
4000 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
4001                                                    G1RedirtyCardsQueueSet* rdcqs,
4002                                                    G1ParScanThreadStateSet* per_thread_states) {
4003   G1GCPhaseTimes* p = phase_times();
4004 
4005   rem_set()->cleanup_after_scan_heap_roots();
4006 
4007   // Process any discovered reference objects - we have
4008   // to do this _before_ we retire the GC alloc regions
4009   // as we may have to copy some 'reachable' referent
4010   // objects (and their reachable sub-graphs) that were
4011   // not copied during the pause.
4012   process_discovered_references(per_thread_states);
4013 
4014   G1STWIsAliveClosure is_alive(this);
4015   G1KeepAliveClosure keep_alive(this);
4016 
4017   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
4018 
4019   if (G1StringDedup::is_enabled()) {
4020     double string_dedup_time_ms = os::elapsedTime();
4021 
4022     string_dedup_cleaning(&is_alive, &keep_alive, p);
4023 
4024     double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
4025     p->record_string_deduplication_time(string_cleanup_time_ms);
4026   }
4027 
4028   _allocator->release_gc_alloc_regions(evacuation_info);
4029 
4030   if (evacuation_failed()) {
4031     restore_after_evac_failure(rdcqs);
4032 
4033     // Reset the G1EvacuationFailureALot counters and flags
4034     NOT_PRODUCT(reset_evacuation_should_fail();)
4035 
4036     double recalculate_used_start = os::elapsedTime();
4037     set_used(recalculate_used());
4038     p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
4039 
4040     if (_archive_allocator != NULL) {
4041       _archive_allocator->clear_used();
4042     }
4043     for (uint i = 0; i < ParallelGCThreads; i++) {
4044       if (_evacuation_failed_info_array[i].has_failed()) {
4045         _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4046       }
4047     }
4048   } else {
4049     // The "used" of the the collection set have already been subtracted
4050     // when they were freed.  Add in the bytes used.
4051     increase_used(_bytes_used_during_gc);
4052   }
4053 
4054   _preserved_marks_set.assert_empty();
4055 
4056   merge_per_thread_state_info(per_thread_states);
4057 
4058   // Reset and re-enable the hot card cache.
4059   // Note the counts for the cards in the regions in the
4060   // collection set are reset when the collection set is freed.
4061   _hot_card_cache->reset_hot_cache();
4062   _hot_card_cache->set_use_cache(true);
4063 
4064   purge_code_root_memory();
4065 
4066   redirty_logged_cards(rdcqs);
4067 
4068   free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4069 
4070   eagerly_reclaim_humongous_regions();
4071 
4072   record_obj_copy_mem_stats();
4073 
4074   evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4075   evacuation_info.set_bytes_used(_bytes_used_during_gc);
4076 
4077 #if COMPILER2_OR_JVMCI
4078   double start = os::elapsedTime();
4079   DerivedPointerTable::update_pointers();
4080   phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4081 #endif
4082   policy()->print_age_table();
4083 }
4084 
4085 void G1CollectedHeap::record_obj_copy_mem_stats() {
4086   policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4087 
4088   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4089                                                create_g1_evac_summary(&_old_evac_stats));
4090 }
4091 
4092 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4093   assert(!hr->is_free(), "the region should not be free");
4094   assert(!hr->is_empty(), "the region should not be empty");
4095   assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4096 
4097   if (G1VerifyBitmaps) {
4098     MemRegion mr(hr->bottom(), hr->end());
4099     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4100   }
4101 
4102   // Clear the card counts for this region.
4103   // Note: we only need to do this if the region is not young
4104   // (since we don't refine cards in young regions).
4105   if (!hr->is_young()) {
4106     _hot_card_cache->reset_card_counts(hr);
4107   }
4108 
4109   // Reset region metadata to allow reuse.
4110   hr->hr_clear(true /* clear_space */);
4111   _policy->remset_tracker()->update_at_free(hr);
4112 
4113   if (free_list != NULL) {
4114     free_list->add_ordered(hr);
4115   }
4116 }
4117 
4118 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4119                                             FreeRegionList* free_list) {
4120   assert(hr->is_humongous(), "this is only for humongous regions");
4121   assert(free_list != NULL, "pre-condition");
4122   hr->clear_humongous();
4123   free_region(hr, free_list);
4124 }
4125 
4126 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4127                                            const uint humongous_regions_removed) {
4128   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4129     MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4130     _old_set.bulk_remove(old_regions_removed);
4131     _humongous_set.bulk_remove(humongous_regions_removed);
4132   }
4133 
4134 }
4135 
4136 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4137   assert(list != NULL, "list can't be null");
4138   if (!list->is_empty()) {
4139     MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4140     _hrm->insert_list_into_free_list(list);
4141   }
4142 }
4143 
4144 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4145   decrease_used(bytes);
4146 }
4147 
4148 class G1FreeCollectionSetTask : public AbstractGangTask {
4149   // Helper class to keep statistics for the collection set freeing
4150   class FreeCSetStats {
4151     size_t _before_used_bytes;   // Usage in regions successfully evacutate
4152     size_t _after_used_bytes;    // Usage in regions failing evacuation
4153     size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4154     size_t _failure_used_words;  // Live size in failed regions
4155     size_t _failure_waste_words; // Wasted size in failed regions
4156     size_t _rs_length;           // Remembered set size
4157     uint _regions_freed;         // Number of regions freed
4158   public:
4159     FreeCSetStats() :
4160         _before_used_bytes(0),
4161         _after_used_bytes(0),
4162         _bytes_allocated_in_old_since_last_gc(0),
4163         _failure_used_words(0),
4164         _failure_waste_words(0),
4165         _rs_length(0),
4166         _regions_freed(0) { }
4167 
4168     void merge_stats(FreeCSetStats* other) {
4169       assert(other != NULL, "invariant");
4170       _before_used_bytes += other->_before_used_bytes;
4171       _after_used_bytes += other->_after_used_bytes;
4172       _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4173       _failure_used_words += other->_failure_used_words;
4174       _failure_waste_words += other->_failure_waste_words;
4175       _rs_length += other->_rs_length;
4176       _regions_freed += other->_regions_freed;
4177     }
4178 
4179     void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4180       evacuation_info->set_regions_freed(_regions_freed);
4181       evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4182 
4183       g1h->decrement_summary_bytes(_before_used_bytes);
4184       g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4185 
4186       G1Policy *policy = g1h->policy();
4187       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4188       policy->record_rs_length(_rs_length);
4189       policy->cset_regions_freed();
4190     }
4191 
4192     void account_failed_region(HeapRegion* r) {
4193       size_t used_words = r->marked_bytes() / HeapWordSize;
4194       _failure_used_words += used_words;
4195       _failure_waste_words += HeapRegion::GrainWords - used_words;
4196       _after_used_bytes += r->used();
4197 
4198       // When moving a young gen region to old gen, we "allocate" that whole
4199       // region there. This is in addition to any already evacuated objects.
4200       // Notify the policy about that. Old gen regions do not cause an
4201       // additional allocation: both the objects still in the region and the
4202       // ones already moved are accounted for elsewhere.
4203       if (r->is_young()) {
4204         _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4205       }
4206     }
4207 
4208     void account_evacuated_region(HeapRegion* r) {
4209       _before_used_bytes += r->used();
4210       _regions_freed += 1;
4211     }
4212 
4213     void account_rs_length(HeapRegion* r) {
4214       _rs_length += r->rem_set()->occupied();
4215     }
4216   };
4217 
4218   // Closure applied to all regions in the collection set.
4219   class FreeCSetClosure : public HeapRegionClosure {
4220     // Helper to send JFR events for regions.
4221     class JFREventForRegion {
4222       EventGCPhaseParallel _event;
4223     public:
4224       JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4225         _event.set_gcId(GCId::current());
4226         _event.set_gcWorkerId(worker_id);
4227         if (region->is_young()) {
4228           _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4229         } else {
4230           _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4231         }
4232       }
4233 
4234       ~JFREventForRegion() {
4235         _event.commit();
4236       }
4237     };
4238 
4239     // Helper to do timing for region work.
4240     class TimerForRegion {
4241       Tickspan& _time;
4242       Ticks     _start_time;
4243     public:
4244       TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4245       ~TimerForRegion() {
4246         _time += Ticks::now() - _start_time;
4247       }
4248     };
4249 
4250     // FreeCSetClosure members
4251     G1CollectedHeap* _g1h;
4252     const size_t*    _surviving_young_words;
4253     uint             _worker_id;
4254     Tickspan         _young_time;
4255     Tickspan         _non_young_time;
4256     FreeCSetStats*   _stats;
4257 
4258     void assert_in_cset(HeapRegion* r) {
4259       assert(r->young_index_in_cset() != 0 &&
4260              (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4261              "Young index %u is wrong for region %u of type %s with %u young regions",
4262              r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4263     }
4264 
4265     void handle_evacuated_region(HeapRegion* r) {
4266       assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4267       stats()->account_evacuated_region(r);
4268 
4269       // Free the region and and its remembered set.
4270       _g1h->free_region(r, NULL);
4271     }
4272 
4273     void handle_failed_region(HeapRegion* r) {
4274       // Do some allocation statistics accounting. Regions that failed evacuation
4275       // are always made old, so there is no need to update anything in the young
4276       // gen statistics, but we need to update old gen statistics.
4277       stats()->account_failed_region(r);
4278 
4279       // Update the region state due to the failed evacuation.
4280       r->handle_evacuation_failure();
4281 
4282       // Add region to old set, need to hold lock.
4283       MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4284       _g1h->old_set_add(r);
4285     }
4286 
4287     Tickspan& timer_for_region(HeapRegion* r) {
4288       return r->is_young() ? _young_time : _non_young_time;
4289     }
4290 
4291     FreeCSetStats* stats() {
4292       return _stats;
4293     }
4294   public:
4295     FreeCSetClosure(const size_t* surviving_young_words,
4296                     uint worker_id,
4297                     FreeCSetStats* stats) :
4298         HeapRegionClosure(),
4299         _g1h(G1CollectedHeap::heap()),
4300         _surviving_young_words(surviving_young_words),
4301         _worker_id(worker_id),
4302         _young_time(),
4303         _non_young_time(),
4304         _stats(stats) { }
4305 
4306     virtual bool do_heap_region(HeapRegion* r) {
4307       assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4308       JFREventForRegion event(r, _worker_id);
4309       TimerForRegion timer(timer_for_region(r));
4310 
4311       _g1h->clear_region_attr(r);
4312       stats()->account_rs_length(r);
4313 
4314       if (r->is_young()) {
4315         assert_in_cset(r);
4316         r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4317       }
4318 
4319       if (r->evacuation_failed()) {
4320         handle_failed_region(r);
4321       } else {
4322         handle_evacuated_region(r);
4323       }
4324       assert(!_g1h->is_on_master_free_list(r), "sanity");
4325 
4326       return false;
4327     }
4328 
4329     void report_timing(Tickspan parallel_time) {
4330       G1GCPhaseTimes* pt = _g1h->phase_times();
4331       pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4332       if (_young_time.value() > 0) {
4333         pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4334       }
4335       if (_non_young_time.value() > 0) {
4336         pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4337       }
4338     }
4339   };
4340 
4341   // G1FreeCollectionSetTask members
4342   G1CollectedHeap*  _g1h;
4343   G1EvacuationInfo* _evacuation_info;
4344   FreeCSetStats*    _worker_stats;
4345   HeapRegionClaimer _claimer;
4346   const size_t*     _surviving_young_words;
4347   uint              _active_workers;
4348 
4349   FreeCSetStats* worker_stats(uint worker) {
4350     return &_worker_stats[worker];
4351   }
4352 
4353   void report_statistics() {
4354     // Merge the accounting
4355     FreeCSetStats total_stats;
4356     for (uint worker = 0; worker < _active_workers; worker++) {
4357       total_stats.merge_stats(worker_stats(worker));
4358     }
4359     total_stats.report(_g1h, _evacuation_info);
4360   }
4361 
4362 public:
4363   G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4364       AbstractGangTask("G1 Free Collection Set"),
4365       _g1h(G1CollectedHeap::heap()),
4366       _evacuation_info(evacuation_info),
4367       _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4368       _claimer(active_workers),
4369       _surviving_young_words(surviving_young_words),
4370       _active_workers(active_workers) {
4371     for (uint worker = 0; worker < active_workers; worker++) {
4372       ::new (&_worker_stats[worker]) FreeCSetStats();
4373     }
4374   }
4375 
4376   ~G1FreeCollectionSetTask() {
4377     Ticks serial_time = Ticks::now();
4378     report_statistics();
4379     for (uint worker = 0; worker < _active_workers; worker++) {
4380       _worker_stats[worker].~FreeCSetStats();
4381     }
4382     FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4383     _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4384   }
4385 
4386   virtual void work(uint worker_id) {
4387     EventGCPhaseParallel event;
4388     Ticks start = Ticks::now();
4389     FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4390     _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4391 
4392     // Report the total parallel time along with some more detailed metrics.
4393     cl.report_timing(Ticks::now() - start);
4394     event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4395   }
4396 };
4397 
4398 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4399   _eden.clear();
4400 
4401   // The free collections set is split up in two tasks, the first
4402   // frees the collection set and records what regions are free,
4403   // and the second one rebuilds the free list. This proved to be
4404   // more efficient than adding a sorted list to another.
4405 
4406   Ticks free_cset_start_time = Ticks::now();
4407   {
4408     uint const num_cs_regions = _collection_set.region_length();
4409     uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4410     G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4411 
4412     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4413                         cl.name(), num_workers, num_cs_regions, num_regions());
4414     workers()->run_task(&cl, num_workers);
4415   }
4416 
4417   Ticks free_cset_end_time = Ticks::now();
4418   phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4419 
4420   // Now rebuild the free region list.
4421   hrm()->rebuild_free_list(workers());
4422   phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4423 
4424   collection_set->clear();
4425 }
4426 
4427 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4428  private:
4429   FreeRegionList* _free_region_list;
4430   HeapRegionSet* _proxy_set;
4431   uint _humongous_objects_reclaimed;
4432   uint _humongous_regions_reclaimed;
4433   size_t _freed_bytes;
4434  public:
4435 
4436   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4437     _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4438   }
4439 
4440   virtual bool do_heap_region(HeapRegion* r) {
4441     if (!r->is_starts_humongous()) {
4442       return false;
4443     }
4444 
4445     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4446 
4447     oop obj = (oop)r->bottom();
4448     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4449 
4450     // The following checks whether the humongous object is live are sufficient.
4451     // The main additional check (in addition to having a reference from the roots
4452     // or the young gen) is whether the humongous object has a remembered set entry.
4453     //
4454     // A humongous object cannot be live if there is no remembered set for it
4455     // because:
4456     // - there can be no references from within humongous starts regions referencing
4457     // the object because we never allocate other objects into them.
4458     // (I.e. there are no intra-region references that may be missed by the
4459     // remembered set)
4460     // - as soon there is a remembered set entry to the humongous starts region
4461     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4462     // until the end of a concurrent mark.
4463     //
4464     // It is not required to check whether the object has been found dead by marking
4465     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4466     // all objects allocated during that time are considered live.
4467     // SATB marking is even more conservative than the remembered set.
4468     // So if at this point in the collection there is no remembered set entry,
4469     // nobody has a reference to it.
4470     // At the start of collection we flush all refinement logs, and remembered sets
4471     // are completely up-to-date wrt to references to the humongous object.
4472     //
4473     // Other implementation considerations:
4474     // - never consider object arrays at this time because they would pose
4475     // considerable effort for cleaning up the the remembered sets. This is
4476     // required because stale remembered sets might reference locations that
4477     // are currently allocated into.
4478     uint region_idx = r->hrm_index();
4479     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4480         !r->rem_set()->is_empty()) {
4481       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",
4482                                region_idx,
4483                                (size_t)obj->size() * HeapWordSize,
4484                                p2i(r->bottom()),
4485                                r->rem_set()->occupied(),
4486                                r->rem_set()->strong_code_roots_list_length(),
4487                                next_bitmap->is_marked(r->bottom()),
4488                                g1h->is_humongous_reclaim_candidate(region_idx),
4489                                obj->is_typeArray()
4490                               );
4491       return false;
4492     }
4493 
4494     guarantee(obj->is_typeArray(),
4495               "Only eagerly reclaiming type arrays is supported, but the object "
4496               PTR_FORMAT " is not.", p2i(r->bottom()));
4497 
4498     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",
4499                              region_idx,
4500                              (size_t)obj->size() * HeapWordSize,
4501                              p2i(r->bottom()),
4502                              r->rem_set()->occupied(),
4503                              r->rem_set()->strong_code_roots_list_length(),
4504                              next_bitmap->is_marked(r->bottom()),
4505                              g1h->is_humongous_reclaim_candidate(region_idx),
4506                              obj->is_typeArray()
4507                             );
4508 
4509     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4510     cm->humongous_object_eagerly_reclaimed(r);
4511     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4512            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4513            region_idx,
4514            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4515            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4516     _humongous_objects_reclaimed++;
4517     do {
4518       HeapRegion* next = g1h->next_region_in_humongous(r);
4519       _freed_bytes += r->used();
4520       r->set_containing_set(NULL);
4521       _humongous_regions_reclaimed++;
4522       g1h->free_humongous_region(r, _free_region_list);
4523       r = next;
4524     } while (r != NULL);
4525 
4526     return false;
4527   }
4528 
4529   uint humongous_objects_reclaimed() {
4530     return _humongous_objects_reclaimed;
4531   }
4532 
4533   uint humongous_regions_reclaimed() {
4534     return _humongous_regions_reclaimed;
4535   }
4536 
4537   size_t bytes_freed() const {
4538     return _freed_bytes;
4539   }
4540 };
4541 
4542 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4543   assert_at_safepoint_on_vm_thread();
4544 
4545   if (!G1EagerReclaimHumongousObjects ||
4546       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4547     phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4548     return;
4549   }
4550 
4551   double start_time = os::elapsedTime();
4552 
4553   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4554 
4555   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4556   heap_region_iterate(&cl);
4557 
4558   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4559 
4560   G1HRPrinter* hrp = hr_printer();
4561   if (hrp->is_active()) {
4562     FreeRegionListIterator iter(&local_cleanup_list);
4563     while (iter.more_available()) {
4564       HeapRegion* hr = iter.get_next();
4565       hrp->cleanup(hr);
4566     }
4567   }
4568 
4569   prepend_to_freelist(&local_cleanup_list);
4570   decrement_summary_bytes(cl.bytes_freed());
4571 
4572   phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4573                                                        cl.humongous_objects_reclaimed());
4574 }
4575 
4576 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4577 public:
4578   virtual bool do_heap_region(HeapRegion* r) {
4579     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4580     G1CollectedHeap::heap()->clear_region_attr(r);
4581     r->clear_young_index_in_cset();
4582     return false;
4583   }
4584 };
4585 
4586 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4587   G1AbandonCollectionSetClosure cl;
4588   collection_set_iterate_all(&cl);
4589 
4590   collection_set->clear();
4591   collection_set->stop_incremental_building();
4592 }
4593 
4594 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4595   return _allocator->is_retained_old_region(hr);
4596 }
4597 
4598 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4599   _eden.add(hr);
4600   _policy->set_region_eden(hr);
4601 }
4602 
4603 #ifdef ASSERT
4604 
4605 class NoYoungRegionsClosure: public HeapRegionClosure {
4606 private:
4607   bool _success;
4608 public:
4609   NoYoungRegionsClosure() : _success(true) { }
4610   bool do_heap_region(HeapRegion* r) {
4611     if (r->is_young()) {
4612       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4613                             p2i(r->bottom()), p2i(r->end()));
4614       _success = false;
4615     }
4616     return false;
4617   }
4618   bool success() { return _success; }
4619 };
4620 
4621 bool G1CollectedHeap::check_young_list_empty() {
4622   bool ret = (young_regions_count() == 0);
4623 
4624   NoYoungRegionsClosure closure;
4625   heap_region_iterate(&closure);
4626   ret = ret && closure.success();
4627 
4628   return ret;
4629 }
4630 
4631 #endif // ASSERT
4632 
4633 class TearDownRegionSetsClosure : public HeapRegionClosure {
4634   HeapRegionSet *_old_set;
4635 
4636 public:
4637   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4638 
4639   bool do_heap_region(HeapRegion* r) {
4640     if (r->is_old()) {
4641       _old_set->remove(r);
4642     } else if(r->is_young()) {
4643       r->uninstall_surv_rate_group();
4644     } else {
4645       // We ignore free regions, we'll empty the free list afterwards.
4646       // We ignore humongous and archive regions, we're not tearing down these
4647       // sets.
4648       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4649              "it cannot be another type");
4650     }
4651     return false;
4652   }
4653 
4654   ~TearDownRegionSetsClosure() {
4655     assert(_old_set->is_empty(), "post-condition");
4656   }
4657 };
4658 
4659 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4660   assert_at_safepoint_on_vm_thread();
4661 
4662   if (!free_list_only) {
4663     TearDownRegionSetsClosure cl(&_old_set);
4664     heap_region_iterate(&cl);
4665 
4666     // Note that emptying the _young_list is postponed and instead done as
4667     // the first step when rebuilding the regions sets again. The reason for
4668     // this is that during a full GC string deduplication needs to know if
4669     // a collected region was young or old when the full GC was initiated.
4670   }
4671   _hrm->remove_all_free_regions();
4672 }
4673 
4674 void G1CollectedHeap::increase_used(size_t bytes) {
4675   _summary_bytes_used += bytes;
4676 }
4677 
4678 void G1CollectedHeap::decrease_used(size_t bytes) {
4679   assert(_summary_bytes_used >= bytes,
4680          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4681          _summary_bytes_used, bytes);
4682   _summary_bytes_used -= bytes;
4683 }
4684 
4685 void G1CollectedHeap::set_used(size_t bytes) {
4686   _summary_bytes_used = bytes;
4687 }
4688 
4689 class RebuildRegionSetsClosure : public HeapRegionClosure {
4690 private:
4691   bool _free_list_only;
4692 
4693   HeapRegionSet* _old_set;
4694   HeapRegionManager* _hrm;
4695 
4696   size_t _total_used;
4697 
4698 public:
4699   RebuildRegionSetsClosure(bool free_list_only,
4700                            HeapRegionSet* old_set,
4701                            HeapRegionManager* hrm) :
4702     _free_list_only(free_list_only),
4703     _old_set(old_set), _hrm(hrm), _total_used(0) {
4704     assert(_hrm->num_free_regions() == 0, "pre-condition");
4705     if (!free_list_only) {
4706       assert(_old_set->is_empty(), "pre-condition");
4707     }
4708   }
4709 
4710   bool do_heap_region(HeapRegion* r) {
4711     if (r->is_empty()) {
4712       assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4713       // Add free regions to the free list
4714       r->set_free();
4715       _hrm->insert_into_free_list(r);
4716     } else if (!_free_list_only) {
4717       assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4718 
4719       if (r->is_archive() || r->is_humongous()) {
4720         // We ignore archive and humongous regions. We left these sets unchanged.
4721       } else {
4722         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4723         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4724         r->move_to_old();
4725         _old_set->add(r);
4726       }
4727       _total_used += r->used();
4728     }
4729 
4730     return false;
4731   }
4732 
4733   size_t total_used() {
4734     return _total_used;
4735   }
4736 };
4737 
4738 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4739   assert_at_safepoint_on_vm_thread();
4740 
4741   if (!free_list_only) {
4742     _eden.clear();
4743     _survivor.clear();
4744   }
4745 
4746   RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4747   heap_region_iterate(&cl);
4748 
4749   if (!free_list_only) {
4750     set_used(cl.total_used());
4751     if (_archive_allocator != NULL) {
4752       _archive_allocator->clear_used();
4753     }
4754   }
4755   assert_used_and_recalculate_used_equal(this);
4756 }
4757 
4758 // Methods for the mutator alloc region
4759 
4760 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4761                                                       bool force,
4762                                                       uint node_index) {
4763   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4764   bool should_allocate = policy()->should_allocate_mutator_region();
4765   if (force || should_allocate) {
4766     HeapRegion* new_alloc_region = new_region(word_size,
4767                                               HeapRegionType::Eden,
4768                                               false /* do_expand */,
4769                                               node_index);
4770     if (new_alloc_region != NULL) {
4771       set_region_short_lived_locked(new_alloc_region);
4772       _hr_printer.alloc(new_alloc_region, !should_allocate);
4773       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4774       _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4775       return new_alloc_region;
4776     }
4777   }
4778   return NULL;
4779 }
4780 
4781 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4782                                                   size_t allocated_bytes) {
4783   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4784   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4785 
4786   collection_set()->add_eden_region(alloc_region);
4787   increase_used(allocated_bytes);
4788   _eden.add_used_bytes(allocated_bytes);
4789   _hr_printer.retire(alloc_region);
4790 
4791   // We update the eden sizes here, when the region is retired,
4792   // instead of when it's allocated, since this is the point that its
4793   // used space has been recorded in _summary_bytes_used.
4794   g1mm()->update_eden_size();
4795 }
4796 
4797 // Methods for the GC alloc regions
4798 
4799 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4800   if (dest.is_old()) {
4801     return true;
4802   } else {
4803     return survivor_regions_count() < policy()->max_survivor_regions();
4804   }
4805 }
4806 
4807 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4808   assert(FreeList_lock->owned_by_self(), "pre-condition");
4809 
4810   if (!has_more_regions(dest)) {
4811     return NULL;
4812   }
4813 
4814   HeapRegionType type;
4815   if (dest.is_young()) {
4816     type = HeapRegionType::Survivor;
4817   } else {
4818     type = HeapRegionType::Old;
4819   }
4820 
4821   HeapRegion* new_alloc_region = new_region(word_size,
4822                                             type,
4823                                             true /* do_expand */,
4824                                             node_index);
4825 
4826   if (new_alloc_region != NULL) {
4827     if (type.is_survivor()) {
4828       new_alloc_region->set_survivor();
4829       _survivor.add(new_alloc_region);
4830       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4831     } else {
4832       new_alloc_region->set_old();
4833       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4834     }
4835     _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4836     register_region_with_region_attr(new_alloc_region);
4837     _hr_printer.alloc(new_alloc_region);
4838     return new_alloc_region;
4839   }
4840   return NULL;
4841 }
4842 
4843 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4844                                              size_t allocated_bytes,
4845                                              G1HeapRegionAttr dest) {
4846   _bytes_used_during_gc += allocated_bytes;
4847   if (dest.is_old()) {
4848     old_set_add(alloc_region);
4849   } else {
4850     assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4851     _survivor.add_used_bytes(allocated_bytes);
4852   }
4853 
4854   bool const during_im = collector_state()->in_initial_mark_gc();
4855   if (during_im && allocated_bytes > 0) {
4856     _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4857   }
4858   _hr_printer.retire(alloc_region);
4859 }
4860 
4861 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4862   bool expanded = false;
4863   uint index = _hrm->find_highest_free(&expanded);
4864 
4865   if (index != G1_NO_HRM_INDEX) {
4866     if (expanded) {
4867       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4868                                 HeapRegion::GrainWords * HeapWordSize);
4869     }
4870     _hrm->allocate_free_regions_starting_at(index, 1);
4871     return region_at(index);
4872   }
4873   return NULL;
4874 }
4875 
4876 // Optimized nmethod scanning
4877 
4878 class RegisterNMethodOopClosure: public OopClosure {
4879   G1CollectedHeap* _g1h;
4880   nmethod* _nm;
4881 
4882   template <class T> void do_oop_work(T* p) {
4883     T heap_oop = RawAccess<>::oop_load(p);
4884     if (!CompressedOops::is_null(heap_oop)) {
4885       oop obj = CompressedOops::decode_not_null(heap_oop);
4886       HeapRegion* hr = _g1h->heap_region_containing(obj);
4887       assert(!hr->is_continues_humongous(),
4888              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4889              " starting at " HR_FORMAT,
4890              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4891 
4892       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4893       hr->add_strong_code_root_locked(_nm);
4894     }
4895   }
4896 
4897 public:
4898   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4899     _g1h(g1h), _nm(nm) {}
4900 
4901   void do_oop(oop* p)       { do_oop_work(p); }
4902   void do_oop(narrowOop* p) { do_oop_work(p); }
4903 };
4904 
4905 class UnregisterNMethodOopClosure: public OopClosure {
4906   G1CollectedHeap* _g1h;
4907   nmethod* _nm;
4908 
4909   template <class T> void do_oop_work(T* p) {
4910     T heap_oop = RawAccess<>::oop_load(p);
4911     if (!CompressedOops::is_null(heap_oop)) {
4912       oop obj = CompressedOops::decode_not_null(heap_oop);
4913       HeapRegion* hr = _g1h->heap_region_containing(obj);
4914       assert(!hr->is_continues_humongous(),
4915              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4916              " starting at " HR_FORMAT,
4917              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4918 
4919       hr->remove_strong_code_root(_nm);
4920     }
4921   }
4922 
4923 public:
4924   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4925     _g1h(g1h), _nm(nm) {}
4926 
4927   void do_oop(oop* p)       { do_oop_work(p); }
4928   void do_oop(narrowOop* p) { do_oop_work(p); }
4929 };
4930 
4931 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4932   guarantee(nm != NULL, "sanity");
4933   RegisterNMethodOopClosure reg_cl(this, nm);
4934   nm->oops_do(&reg_cl);
4935 }
4936 
4937 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4938   guarantee(nm != NULL, "sanity");
4939   UnregisterNMethodOopClosure reg_cl(this, nm);
4940   nm->oops_do(&reg_cl, true);
4941 }
4942 
4943 void G1CollectedHeap::purge_code_root_memory() {
4944   double purge_start = os::elapsedTime();
4945   G1CodeRootSet::purge();
4946   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4947   phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4948 }
4949 
4950 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4951   G1CollectedHeap* _g1h;
4952 
4953 public:
4954   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4955     _g1h(g1h) {}
4956 
4957   void do_code_blob(CodeBlob* cb) {
4958     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4959     if (nm == NULL) {
4960       return;
4961     }
4962 
4963     _g1h->register_nmethod(nm);
4964   }
4965 };
4966 
4967 void G1CollectedHeap::rebuild_strong_code_roots() {
4968   RebuildStrongCodeRootClosure blob_cl(this);
4969   CodeCache::blobs_do(&blob_cl);
4970 }
4971 
4972 void G1CollectedHeap::initialize_serviceability() {
4973   _g1mm->initialize_serviceability();
4974 }
4975 
4976 MemoryUsage G1CollectedHeap::memory_usage() {
4977   return _g1mm->memory_usage();
4978 }
4979 
4980 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4981   return _g1mm->memory_managers();
4982 }
4983 
4984 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4985   return _g1mm->memory_pools();
4986 }
--- EOF ---