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/g1GCParPhaseTimesTracker.hpp"
  45 #include "gc/g1/g1GCPhaseTimes.hpp"
  46 #include "gc/g1/g1HeapSizingPolicy.hpp"
  47 #include "gc/g1/g1HeapTransition.hpp"
  48 #include "gc/g1/g1HeapVerifier.hpp"
  49 #include "gc/g1/g1HotCardCache.hpp"
  50 #include "gc/g1/g1InitLogger.hpp"
  51 #include "gc/g1/g1MemoryPool.hpp"
  52 #include "gc/g1/g1OopClosures.inline.hpp"
  53 #include "gc/g1/g1ParallelCleaning.hpp"
  54 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  55 #include "gc/g1/g1Policy.hpp"
  56 #include "gc/g1/g1RedirtyCardsQueue.hpp"
  57 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  58 #include "gc/g1/g1RemSet.hpp"
  59 #include "gc/g1/g1RootClosures.hpp"
  60 #include "gc/g1/g1RootProcessor.hpp"
  61 #include "gc/g1/g1SATBMarkQueueSet.hpp"
  62 #include "gc/g1/g1StringDedup.hpp"
  63 #include "gc/g1/g1ThreadLocalData.hpp"
  64 #include "gc/g1/g1Trace.hpp"
  65 #include "gc/g1/g1YCTypes.hpp"
  66 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  67 #include "gc/g1/g1VMOperations.hpp"
  68 #include "gc/g1/heapRegion.inline.hpp"
  69 #include "gc/g1/heapRegionRemSet.hpp"
  70 #include "gc/g1/heapRegionSet.inline.hpp"
  71 #include "gc/shared/concurrentGCBreakpoints.hpp"
  72 #include "gc/shared/gcBehaviours.hpp"
  73 #include "gc/shared/gcHeapSummary.hpp"
  74 #include "gc/shared/gcId.hpp"
  75 #include "gc/shared/gcLocker.hpp"
  76 #include "gc/shared/gcTimer.hpp"
  77 #include "gc/shared/gcTraceTime.inline.hpp"
  78 #include "gc/shared/generationSpec.hpp"
  79 #include "gc/shared/isGCActiveMark.hpp"
  80 #include "gc/shared/locationPrinter.inline.hpp"
  81 #include "gc/shared/oopStorageParState.hpp"
  82 #include "gc/shared/preservedMarks.inline.hpp"
  83 #include "gc/shared/suspendibleThreadSet.hpp"
  84 #include "gc/shared/referenceProcessor.inline.hpp"
  85 #include "gc/shared/taskTerminator.hpp"
  86 #include "gc/shared/taskqueue.inline.hpp"
  87 #include "gc/shared/weakProcessor.inline.hpp"
  88 #include "gc/shared/workerPolicy.hpp"
  89 #include "logging/log.hpp"
  90 #include "memory/allocation.hpp"
  91 #include "memory/iterator.hpp"
  92 #include "memory/heapInspection.hpp"
  93 #include "memory/resourceArea.hpp"
  94 #include "memory/universe.hpp"
  95 #include "oops/access.inline.hpp"
  96 #include "oops/compressedOops.inline.hpp"
  97 #include "oops/oop.inline.hpp"
  98 #include "runtime/atomic.hpp"
  99 #include "runtime/handles.inline.hpp"
 100 #include "runtime/init.hpp"
 101 #include "runtime/orderAccess.hpp"
 102 #include "runtime/threadSMR.hpp"
 103 #include "runtime/vmThread.hpp"
 104 #include "utilities/align.hpp"
 105 #include "utilities/autoRestore.hpp"
 106 #include "utilities/bitMap.inline.hpp"
 107 #include "utilities/globalDefinitions.hpp"
 108 #include "utilities/stack.inline.hpp"
 109 
 110 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
 111 
 112 // INVARIANTS/NOTES
 113 //
 114 // All allocation activity covered by the G1CollectedHeap interface is
 115 // serialized by acquiring the HeapLock.  This happens in mem_allocate
 116 // and allocate_new_tlab, which are the "entry" points to the
 117 // allocation code from the rest of the JVM.  (Note that this does not
 118 // apply to TLAB allocation, which is not part of this interface: it
 119 // is done by clients of this interface.)
 120 
 121 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
 122  private:
 123   size_t _num_dirtied;
 124   G1CollectedHeap* _g1h;
 125   G1CardTable* _g1_ct;
 126 
 127   HeapRegion* region_for_card(CardValue* card_ptr) const {
 128     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
 129   }
 130 
 131   bool will_become_free(HeapRegion* hr) const {
 132     // A region will be freed by free_collection_set if the region is in the
 133     // collection set and has not had an evacuation failure.
 134     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 135   }
 136 
 137  public:
 138   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
 139     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
 140 
 141   void do_card_ptr(CardValue* card_ptr, uint worker_id) {
 142     HeapRegion* hr = region_for_card(card_ptr);
 143 
 144     // Should only dirty cards in regions that won't be freed.
 145     if (!will_become_free(hr)) {
 146       *card_ptr = G1CardTable::dirty_card_val();
 147       _num_dirtied++;
 148     }
 149   }
 150 
 151   size_t num_dirtied()   const { return _num_dirtied; }
 152 };
 153 
 154 
 155 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 156   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 157 }
 158 
 159 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 160   // The from card cache is not the memory that is actually committed. So we cannot
 161   // take advantage of the zero_filled parameter.
 162   reset_from_card_cache(start_idx, num_regions);
 163 }
 164 
 165 void G1CollectedHeap::run_task(AbstractGangTask* task) {
 166   workers()->run_task(task, workers()->active_workers());
 167 }
 168 
 169 Tickspan G1CollectedHeap::run_task_timed(AbstractGangTask* task) {
 170   Ticks start = Ticks::now();
 171   run_task(task);
 172   return Ticks::now() - start;
 173 }
 174 
 175 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 176                                              MemRegion mr) {
 177   return new HeapRegion(hrs_index, bot(), mr);
 178 }
 179 
 180 // Private methods.
 181 
 182 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
 183                                         HeapRegionType type,
 184                                         bool do_expand,
 185                                         uint node_index) {
 186   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 187          "the only time we use this to allocate a humongous region is "
 188          "when we are allocating a single humongous region");
 189 
 190   HeapRegion* res = _hrm->allocate_free_region(type, node_index);
 191 
 192   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 193     // Currently, only attempts to allocate GC alloc regions set
 194     // do_expand to true. So, we should only reach here during a
 195     // safepoint. If this assumption changes we might have to
 196     // reconsider the use of _expand_heap_after_alloc_failure.
 197     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 198 
 199     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 200                               word_size * HeapWordSize);
 201 
 202     assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
 203            "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
 204            word_size * HeapWordSize);
 205     if (expand_single_region(node_index)) {
 206       // Given that expand_single_region() succeeded in expanding the heap, and we
 207       // always expand the heap by an amount aligned to the heap
 208       // region size, the free list should in theory not be empty.
 209       // In either case allocate_free_region() will check for NULL.
 210       res = _hrm->allocate_free_region(type, node_index);
 211     } else {
 212       _expand_heap_after_alloc_failure = false;
 213     }
 214   }
 215   return res;
 216 }
 217 
 218 HeapWord*
 219 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
 220                                                            uint num_regions,
 221                                                            size_t word_size) {
 222   assert(first_hr != NULL, "pre-condition");
 223   assert(is_humongous(word_size), "word_size should be humongous");
 224   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 225 
 226   // Index of last region in the series.
 227   uint first = first_hr->hrm_index();
 228   uint last = first + num_regions - 1;
 229 
 230   // We need to initialize the region(s) we just discovered. This is
 231   // a bit tricky given that it can happen concurrently with
 232   // refinement threads refining cards on these regions and
 233   // potentially wanting to refine the BOT as they are scanning
 234   // those cards (this can happen shortly after a cleanup; see CR
 235   // 6991377). So we have to set up the region(s) carefully and in
 236   // a specific order.
 237 
 238   // The word size sum of all the regions we will allocate.
 239   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 240   assert(word_size <= word_size_sum, "sanity");
 241 
 242   // The passed in hr will be the "starts humongous" region. The header
 243   // of the new object will be placed at the bottom of this region.
 244   HeapWord* new_obj = first_hr->bottom();
 245   // This will be the new top of the new object.
 246   HeapWord* obj_top = new_obj + word_size;
 247 
 248   // First, we need to zero the header of the space that we will be
 249   // allocating. When we update top further down, some refinement
 250   // threads might try to scan the region. By zeroing the header we
 251   // ensure that any thread that will try to scan the region will
 252   // come across the zero klass word and bail out.
 253   //
 254   // NOTE: It would not have been correct to have used
 255   // CollectedHeap::fill_with_object() and make the space look like
 256   // an int array. The thread that is doing the allocation will
 257   // later update the object header to a potentially different array
 258   // type and, for a very short period of time, the klass and length
 259   // fields will be inconsistent. This could cause a refinement
 260   // thread to calculate the object size incorrectly.
 261   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 262 
 263   // Next, pad out the unused tail of the last region with filler
 264   // objects, for improved usage accounting.
 265   // How many words we use for filler objects.
 266   size_t word_fill_size = word_size_sum - word_size;
 267 
 268   // How many words memory we "waste" which cannot hold a filler object.
 269   size_t words_not_fillable = 0;
 270 
 271   if (word_fill_size >= min_fill_size()) {
 272     fill_with_objects(obj_top, word_fill_size);
 273   } else if (word_fill_size > 0) {
 274     // We have space to fill, but we cannot fit an object there.
 275     words_not_fillable = word_fill_size;
 276     word_fill_size = 0;
 277   }
 278 
 279   // We will set up the first region as "starts humongous". This
 280   // will also update the BOT covering all the regions to reflect
 281   // that there is a single object that starts at the bottom of the
 282   // first region.
 283   first_hr->set_starts_humongous(obj_top, word_fill_size);
 284   _policy->remset_tracker()->update_at_allocate(first_hr);
 285   // Then, if there are any, we will set up the "continues
 286   // humongous" regions.
 287   HeapRegion* hr = NULL;
 288   for (uint i = first + 1; i <= last; ++i) {
 289     hr = region_at(i);
 290     hr->set_continues_humongous(first_hr);
 291     _policy->remset_tracker()->update_at_allocate(hr);
 292   }
 293 
 294   // Up to this point no concurrent thread would have been able to
 295   // do any scanning on any region in this series. All the top
 296   // fields still point to bottom, so the intersection between
 297   // [bottom,top] and [card_start,card_end] will be empty. Before we
 298   // update the top fields, we'll do a storestore to make sure that
 299   // no thread sees the update to top before the zeroing of the
 300   // object header and the BOT initialization.
 301   OrderAccess::storestore();
 302 
 303   // Now, we will update the top fields of the "continues humongous"
 304   // regions except the last one.
 305   for (uint i = first; i < last; ++i) {
 306     hr = region_at(i);
 307     hr->set_top(hr->end());
 308   }
 309 
 310   hr = region_at(last);
 311   // If we cannot fit a filler object, we must set top to the end
 312   // of the humongous object, otherwise we cannot iterate the heap
 313   // and the BOT will not be complete.
 314   hr->set_top(hr->end() - words_not_fillable);
 315 
 316   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 317          "obj_top should be in last region");
 318 
 319   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 320 
 321   assert(words_not_fillable == 0 ||
 322          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 323          "Miscalculation in humongous allocation");
 324 
 325   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 326 
 327   for (uint i = first; i <= last; ++i) {
 328     hr = region_at(i);
 329     _humongous_set.add(hr);
 330     _hr_printer.alloc(hr);
 331   }
 332 
 333   return new_obj;
 334 }
 335 
 336 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 337   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 338   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 339 }
 340 
 341 // If could fit into free regions w/o expansion, try.
 342 // Otherwise, if can expand, do so.
 343 // Otherwise, if using ex regions might help, try with ex given back.
 344 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 345   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 346 
 347   _verifier->verify_region_sets_optional();
 348 
 349   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 350 
 351   // Policy: First try to allocate a humongous object in the free list.
 352   HeapRegion* humongous_start = _hrm->allocate_humongous(obj_regions);
 353   if (humongous_start == NULL) {
 354     // Policy: We could not find enough regions for the humongous object in the
 355     // free list. Look through the heap to find a mix of free and uncommitted regions.
 356     // If so, expand the heap and allocate the humongous object.
 357     humongous_start = _hrm->expand_and_allocate_humongous(obj_regions);
 358     if (humongous_start != NULL) {
 359       // We managed to find a region by expanding the heap.
 360       log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
 361                                 word_size * HeapWordSize);
 362       policy()->record_new_heap_size(num_regions());
 363     } else {
 364       // Policy: Potentially trigger a defragmentation GC.
 365     }
 366   }
 367 
 368   HeapWord* result = NULL;
 369   if (humongous_start != NULL) {
 370     result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
 371     assert(result != NULL, "it should always return a valid result");
 372 
 373     // A successful humongous object allocation changes the used space
 374     // information of the old generation so we need to recalculate the
 375     // sizes and update the jstat counters here.
 376     g1mm()->update_sizes();
 377   }
 378 
 379   _verifier->verify_region_sets_optional();
 380 
 381   return result;
 382 }
 383 
 384 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
 385                                              size_t requested_size,
 386                                              size_t* actual_size) {
 387   assert_heap_not_locked_and_not_at_safepoint();
 388   assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
 389 
 390   return attempt_allocation(min_size, requested_size, actual_size);
 391 }
 392 
 393 HeapWord*
 394 G1CollectedHeap::mem_allocate(size_t word_size,
 395                               bool*  gc_overhead_limit_was_exceeded) {
 396   assert_heap_not_locked_and_not_at_safepoint();
 397 
 398   if (is_humongous(word_size)) {
 399     return attempt_allocation_humongous(word_size);
 400   }
 401   size_t dummy = 0;
 402   return attempt_allocation(word_size, word_size, &dummy);
 403 }
 404 
 405 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 406   ResourceMark rm; // For retrieving the thread names in log messages.
 407 
 408   // Make sure you read the note in attempt_allocation_humongous().
 409 
 410   assert_heap_not_locked_and_not_at_safepoint();
 411   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 412          "be called for humongous allocation requests");
 413 
 414   // We should only get here after the first-level allocation attempt
 415   // (attempt_allocation()) failed to allocate.
 416 
 417   // We will loop until a) we manage to successfully perform the
 418   // allocation or b) we successfully schedule a collection which
 419   // fails to perform the allocation. b) is the only case when we'll
 420   // return NULL.
 421   HeapWord* result = NULL;
 422   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 423     bool should_try_gc;
 424     uint gc_count_before;
 425 
 426     {
 427       MutexLocker x(Heap_lock);
 428       result = _allocator->attempt_allocation_locked(word_size);
 429       if (result != NULL) {
 430         return result;
 431       }
 432 
 433       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 434       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 435       // waiting because the GCLocker is active to not wait too long.
 436       if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
 437         // No need for an ergo message here, can_expand_young_list() does this when
 438         // it returns true.
 439         result = _allocator->attempt_allocation_force(word_size);
 440         if (result != NULL) {
 441           return result;
 442         }
 443       }
 444       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 445       // the GCLocker initiated GC has been performed and then retry. This includes
 446       // the case when the GC Locker is not active but has not been performed.
 447       should_try_gc = !GCLocker::needs_gc();
 448       // Read the GC count while still holding the Heap_lock.
 449       gc_count_before = total_collections();
 450     }
 451 
 452     if (should_try_gc) {
 453       bool succeeded;
 454       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 455                                    GCCause::_g1_inc_collection_pause);
 456       if (result != NULL) {
 457         assert(succeeded, "only way to get back a non-NULL result");
 458         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 459                              Thread::current()->name(), p2i(result));
 460         return result;
 461       }
 462 
 463       if (succeeded) {
 464         // We successfully scheduled a collection which failed to allocate. No
 465         // point in trying to allocate further. We'll just return NULL.
 466         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 467                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 468         return NULL;
 469       }
 470       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 471                            Thread::current()->name(), word_size);
 472     } else {
 473       // Failed to schedule a collection.
 474       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 475         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 476                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 477         return NULL;
 478       }
 479       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 480       // The GCLocker is either active or the GCLocker initiated
 481       // GC has not yet been performed. Stall until it is and
 482       // then retry the allocation.
 483       GCLocker::stall_until_clear();
 484       gclocker_retry_count += 1;
 485     }
 486 
 487     // We can reach here if we were unsuccessful in scheduling a
 488     // collection (because another thread beat us to it) or if we were
 489     // stalled due to the GC locker. In either can we should retry the
 490     // allocation attempt in case another thread successfully
 491     // performed a collection and reclaimed enough space. We do the
 492     // first attempt (without holding the Heap_lock) here and the
 493     // follow-on attempt will be at the start of the next loop
 494     // iteration (after taking the Heap_lock).
 495     size_t dummy = 0;
 496     result = _allocator->attempt_allocation(word_size, word_size, &dummy);
 497     if (result != NULL) {
 498       return result;
 499     }
 500 
 501     // Give a warning if we seem to be looping forever.
 502     if ((QueuedAllocationWarningCount > 0) &&
 503         (try_count % QueuedAllocationWarningCount == 0)) {
 504       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 505                              Thread::current()->name(), try_count, word_size);
 506     }
 507   }
 508 
 509   ShouldNotReachHere();
 510   return NULL;
 511 }
 512 
 513 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 514   assert_at_safepoint_on_vm_thread();
 515   if (_archive_allocator == NULL) {
 516     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 517   }
 518 }
 519 
 520 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 521   // Allocations in archive regions cannot be of a size that would be considered
 522   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 523   // may be different at archive-restore time.
 524   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 525 }
 526 
 527 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 528   assert_at_safepoint_on_vm_thread();
 529   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 530   if (is_archive_alloc_too_large(word_size)) {
 531     return NULL;
 532   }
 533   return _archive_allocator->archive_mem_allocate(word_size);
 534 }
 535 
 536 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 537                                               size_t end_alignment_in_bytes) {
 538   assert_at_safepoint_on_vm_thread();
 539   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 540 
 541   // Call complete_archive to do the real work, filling in the MemRegion
 542   // array with the archive regions.
 543   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 544   delete _archive_allocator;
 545   _archive_allocator = NULL;
 546 }
 547 
 548 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 549   assert(ranges != NULL, "MemRegion array NULL");
 550   assert(count != 0, "No MemRegions provided");
 551   MemRegion reserved = _hrm->reserved();
 552   for (size_t i = 0; i < count; i++) {
 553     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 554       return false;
 555     }
 556   }
 557   return true;
 558 }
 559 
 560 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 561                                             size_t count,
 562                                             bool open) {
 563   assert(!is_init_completed(), "Expect to be called at JVM init time");
 564   assert(ranges != NULL, "MemRegion array NULL");
 565   assert(count != 0, "No MemRegions provided");
 566   MutexLocker x(Heap_lock);
 567 
 568   MemRegion reserved = _hrm->reserved();
 569   HeapWord* prev_last_addr = NULL;
 570   HeapRegion* prev_last_region = NULL;
 571 
 572   // Temporarily disable pretouching of heap pages. This interface is used
 573   // when mmap'ing archived heap data in, so pre-touching is wasted.
 574   FlagSetting fs(AlwaysPreTouch, false);
 575 
 576   // Enable archive object checking used by G1MarkSweep. We have to let it know
 577   // about each archive range, so that objects in those ranges aren't marked.
 578   G1ArchiveAllocator::enable_archive_object_check();
 579 
 580   // For each specified MemRegion range, allocate the corresponding G1
 581   // regions and mark them as archive regions. We expect the ranges
 582   // in ascending starting address order, without overlap.
 583   for (size_t i = 0; i < count; i++) {
 584     MemRegion curr_range = ranges[i];
 585     HeapWord* start_address = curr_range.start();
 586     size_t word_size = curr_range.word_size();
 587     HeapWord* last_address = curr_range.last();
 588     size_t commits = 0;
 589 
 590     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 591               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 592               p2i(start_address), p2i(last_address));
 593     guarantee(start_address > prev_last_addr,
 594               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 595               p2i(start_address), p2i(prev_last_addr));
 596     prev_last_addr = last_address;
 597 
 598     // Check for ranges that start in the same G1 region in which the previous
 599     // range ended, and adjust the start address so we don't try to allocate
 600     // the same region again. If the current range is entirely within that
 601     // region, skip it, just adjusting the recorded top.
 602     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 603     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 604       start_address = start_region->end();
 605       if (start_address > last_address) {
 606         increase_used(word_size * HeapWordSize);
 607         start_region->set_top(last_address + 1);
 608         continue;
 609       }
 610       start_region->set_top(start_address);
 611       curr_range = MemRegion(start_address, last_address + 1);
 612       start_region = _hrm->addr_to_region(start_address);
 613     }
 614 
 615     // Perform the actual region allocation, exiting if it fails.
 616     // Then note how much new space we have allocated.
 617     if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
 618       return false;
 619     }
 620     increase_used(word_size * HeapWordSize);
 621     if (commits != 0) {
 622       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 623                                 HeapRegion::GrainWords * HeapWordSize * commits);
 624 
 625     }
 626 
 627     // Mark each G1 region touched by the range as archive, add it to
 628     // the old set, and set top.
 629     HeapRegion* curr_region = _hrm->addr_to_region(start_address);
 630     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 631     prev_last_region = last_region;
 632 
 633     while (curr_region != NULL) {
 634       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 635              "Region already in use (index %u)", curr_region->hrm_index());
 636       if (open) {
 637         curr_region->set_open_archive();
 638       } else {
 639         curr_region->set_closed_archive();
 640       }
 641       _hr_printer.alloc(curr_region);
 642       _archive_set.add(curr_region);
 643       HeapWord* top;
 644       HeapRegion* next_region;
 645       if (curr_region != last_region) {
 646         top = curr_region->end();
 647         next_region = _hrm->next_region_in_heap(curr_region);
 648       } else {
 649         top = last_address + 1;
 650         next_region = NULL;
 651       }
 652       curr_region->set_top(top);
 653       curr_region = next_region;
 654     }
 655 
 656     // Notify mark-sweep of the archive
 657     G1ArchiveAllocator::set_range_archive(curr_range, open);
 658   }
 659   return true;
 660 }
 661 
 662 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 663   assert(!is_init_completed(), "Expect to be called at JVM init time");
 664   assert(ranges != NULL, "MemRegion array NULL");
 665   assert(count != 0, "No MemRegions provided");
 666   MemRegion reserved = _hrm->reserved();
 667   HeapWord *prev_last_addr = NULL;
 668   HeapRegion* prev_last_region = NULL;
 669 
 670   // For each MemRegion, create filler objects, if needed, in the G1 regions
 671   // that contain the address range. The address range actually within the
 672   // MemRegion will not be modified. That is assumed to have been initialized
 673   // elsewhere, probably via an mmap of archived heap data.
 674   MutexLocker x(Heap_lock);
 675   for (size_t i = 0; i < count; i++) {
 676     HeapWord* start_address = ranges[i].start();
 677     HeapWord* last_address = ranges[i].last();
 678 
 679     assert(reserved.contains(start_address) && reserved.contains(last_address),
 680            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 681            p2i(start_address), p2i(last_address));
 682     assert(start_address > prev_last_addr,
 683            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 684            p2i(start_address), p2i(prev_last_addr));
 685 
 686     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 687     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 688     HeapWord* bottom_address = start_region->bottom();
 689 
 690     // Check for a range beginning in the same region in which the
 691     // previous one ended.
 692     if (start_region == prev_last_region) {
 693       bottom_address = prev_last_addr + 1;
 694     }
 695 
 696     // Verify that the regions were all marked as archive regions by
 697     // alloc_archive_regions.
 698     HeapRegion* curr_region = start_region;
 699     while (curr_region != NULL) {
 700       guarantee(curr_region->is_archive(),
 701                 "Expected archive region at index %u", curr_region->hrm_index());
 702       if (curr_region != last_region) {
 703         curr_region = _hrm->next_region_in_heap(curr_region);
 704       } else {
 705         curr_region = NULL;
 706       }
 707     }
 708 
 709     prev_last_addr = last_address;
 710     prev_last_region = last_region;
 711 
 712     // Fill the memory below the allocated range with dummy object(s),
 713     // if the region bottom does not match the range start, or if the previous
 714     // range ended within the same G1 region, and there is a gap.
 715     if (start_address != bottom_address) {
 716       size_t fill_size = pointer_delta(start_address, bottom_address);
 717       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 718       increase_used(fill_size * HeapWordSize);
 719     }
 720   }
 721 }
 722 
 723 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
 724                                                      size_t desired_word_size,
 725                                                      size_t* actual_word_size) {
 726   assert_heap_not_locked_and_not_at_safepoint();
 727   assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
 728          "be called for humongous allocation requests");
 729 
 730   HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
 731 
 732   if (result == NULL) {
 733     *actual_word_size = desired_word_size;
 734     result = attempt_allocation_slow(desired_word_size);
 735   }
 736 
 737   assert_heap_not_locked();
 738   if (result != NULL) {
 739     assert(*actual_word_size != 0, "Actual size must have been set here");
 740     dirty_young_block(result, *actual_word_size);
 741   } else {
 742     *actual_word_size = 0;
 743   }
 744 
 745   return result;
 746 }
 747 
 748 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 749   assert(!is_init_completed(), "Expect to be called at JVM init time");
 750   assert(ranges != NULL, "MemRegion array NULL");
 751   assert(count != 0, "No MemRegions provided");
 752   MemRegion reserved = _hrm->reserved();
 753   HeapWord* prev_last_addr = NULL;
 754   HeapRegion* prev_last_region = NULL;
 755   size_t size_used = 0;
 756   size_t uncommitted_regions = 0;
 757 
 758   // For each Memregion, free the G1 regions that constitute it, and
 759   // notify mark-sweep that the range is no longer to be considered 'archive.'
 760   MutexLocker x(Heap_lock);
 761   for (size_t i = 0; i < count; i++) {
 762     HeapWord* start_address = ranges[i].start();
 763     HeapWord* last_address = ranges[i].last();
 764 
 765     assert(reserved.contains(start_address) && reserved.contains(last_address),
 766            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 767            p2i(start_address), p2i(last_address));
 768     assert(start_address > prev_last_addr,
 769            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 770            p2i(start_address), p2i(prev_last_addr));
 771     size_used += ranges[i].byte_size();
 772     prev_last_addr = last_address;
 773 
 774     HeapRegion* start_region = _hrm->addr_to_region(start_address);
 775     HeapRegion* last_region = _hrm->addr_to_region(last_address);
 776 
 777     // Check for ranges that start in the same G1 region in which the previous
 778     // range ended, and adjust the start address so we don't try to free
 779     // the same region again. If the current range is entirely within that
 780     // region, skip it.
 781     if (start_region == prev_last_region) {
 782       start_address = start_region->end();
 783       if (start_address > last_address) {
 784         continue;
 785       }
 786       start_region = _hrm->addr_to_region(start_address);
 787     }
 788     prev_last_region = last_region;
 789 
 790     // After verifying that each region was marked as an archive region by
 791     // alloc_archive_regions, set it free and empty and uncommit it.
 792     HeapRegion* curr_region = start_region;
 793     while (curr_region != NULL) {
 794       guarantee(curr_region->is_archive(),
 795                 "Expected archive region at index %u", curr_region->hrm_index());
 796       uint curr_index = curr_region->hrm_index();
 797       _archive_set.remove(curr_region);
 798       curr_region->set_free();
 799       curr_region->set_top(curr_region->bottom());
 800       if (curr_region != last_region) {
 801         curr_region = _hrm->next_region_in_heap(curr_region);
 802       } else {
 803         curr_region = NULL;
 804       }
 805       _hrm->shrink_at(curr_index, 1);
 806       uncommitted_regions++;
 807     }
 808 
 809     // Notify mark-sweep that this is no longer an archive range.
 810     G1ArchiveAllocator::clear_range_archive(ranges[i]);
 811   }
 812 
 813   if (uncommitted_regions != 0) {
 814     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 815                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 816   }
 817   decrease_used(size_used);
 818 }
 819 
 820 oop G1CollectedHeap::materialize_archived_object(oop obj) {
 821   assert(obj != NULL, "archived obj is NULL");
 822   assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
 823 
 824   // Loading an archived object makes it strongly reachable. If it is
 825   // loaded during concurrent marking, it must be enqueued to the SATB
 826   // queue, shading the previously white object gray.
 827   G1BarrierSet::enqueue(obj);
 828 
 829   return obj;
 830 }
 831 
 832 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 833   ResourceMark rm; // For retrieving the thread names in log messages.
 834 
 835   // The structure of this method has a lot of similarities to
 836   // attempt_allocation_slow(). The reason these two were not merged
 837   // into a single one is that such a method would require several "if
 838   // allocation is not humongous do this, otherwise do that"
 839   // conditional paths which would obscure its flow. In fact, an early
 840   // version of this code did use a unified method which was harder to
 841   // follow and, as a result, it had subtle bugs that were hard to
 842   // track down. So keeping these two methods separate allows each to
 843   // be more readable. It will be good to keep these two in sync as
 844   // much as possible.
 845 
 846   assert_heap_not_locked_and_not_at_safepoint();
 847   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 848          "should only be called for humongous allocations");
 849 
 850   // Humongous objects can exhaust the heap quickly, so we should check if we
 851   // need to start a marking cycle at each humongous object allocation. We do
 852   // the check before we do the actual allocation. The reason for doing it
 853   // before the allocation is that we avoid having to keep track of the newly
 854   // allocated memory while we do a GC.
 855   if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
 856                                            word_size)) {
 857     collect(GCCause::_g1_humongous_allocation);
 858   }
 859 
 860   // We will loop until a) we manage to successfully perform the
 861   // allocation or b) we successfully schedule a collection which
 862   // fails to perform the allocation. b) is the only case when we'll
 863   // return NULL.
 864   HeapWord* result = NULL;
 865   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 866     bool should_try_gc;
 867     uint gc_count_before;
 868 
 869 
 870     {
 871       MutexLocker x(Heap_lock);
 872 
 873       // Given that humongous objects are not allocated in young
 874       // regions, we'll first try to do the allocation without doing a
 875       // collection hoping that there's enough space in the heap.
 876       result = humongous_obj_allocate(word_size);
 877       if (result != NULL) {
 878         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 879         policy()->old_gen_alloc_tracker()->
 880           add_allocated_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 881         return result;
 882       }
 883 
 884       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 885       // the GCLocker initiated GC has been performed and then retry. This includes
 886       // the case when the GC Locker is not active but has not been performed.
 887       should_try_gc = !GCLocker::needs_gc();
 888       // Read the GC count while still holding the Heap_lock.
 889       gc_count_before = total_collections();
 890     }
 891 
 892     if (should_try_gc) {
 893       bool succeeded;
 894       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 895                                    GCCause::_g1_humongous_allocation);
 896       if (result != NULL) {
 897         assert(succeeded, "only way to get back a non-NULL result");
 898         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 899                              Thread::current()->name(), p2i(result));
 900         return result;
 901       }
 902 
 903       if (succeeded) {
 904         // We successfully scheduled a collection which failed to allocate. No
 905         // point in trying to allocate further. We'll just return NULL.
 906         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 907                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 908         return NULL;
 909       }
 910       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 911                            Thread::current()->name(), word_size);
 912     } else {
 913       // Failed to schedule a collection.
 914       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 915         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 916                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 917         return NULL;
 918       }
 919       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 920       // The GCLocker is either active or the GCLocker initiated
 921       // GC has not yet been performed. Stall until it is and
 922       // then retry the allocation.
 923       GCLocker::stall_until_clear();
 924       gclocker_retry_count += 1;
 925     }
 926 
 927 
 928     // We can reach here if we were unsuccessful in scheduling a
 929     // collection (because another thread beat us to it) or if we were
 930     // stalled due to the GC locker. In either can we should retry the
 931     // allocation attempt in case another thread successfully
 932     // performed a collection and reclaimed enough space.
 933     // Humongous object allocation always needs a lock, so we wait for the retry
 934     // in the next iteration of the loop, unlike for the regular iteration case.
 935     // Give a warning if we seem to be looping forever.
 936 
 937     if ((QueuedAllocationWarningCount > 0) &&
 938         (try_count % QueuedAllocationWarningCount == 0)) {
 939       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 940                              Thread::current()->name(), try_count, word_size);
 941     }
 942   }
 943 
 944   ShouldNotReachHere();
 945   return NULL;
 946 }
 947 
 948 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 949                                                            bool expect_null_mutator_alloc_region) {
 950   assert_at_safepoint_on_vm_thread();
 951   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 952          "the current alloc region was unexpectedly found to be non-NULL");
 953 
 954   if (!is_humongous(word_size)) {
 955     return _allocator->attempt_allocation_locked(word_size);
 956   } else {
 957     HeapWord* result = humongous_obj_allocate(word_size);
 958     if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
 959       collector_state()->set_initiate_conc_mark_if_possible(true);
 960     }
 961     return result;
 962   }
 963 
 964   ShouldNotReachHere();
 965 }
 966 
 967 class PostCompactionPrinterClosure: public HeapRegionClosure {
 968 private:
 969   G1HRPrinter* _hr_printer;
 970 public:
 971   bool do_heap_region(HeapRegion* hr) {
 972     assert(!hr->is_young(), "not expecting to find young regions");
 973     _hr_printer->post_compaction(hr);
 974     return false;
 975   }
 976 
 977   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 978     : _hr_printer(hr_printer) { }
 979 };
 980 
 981 void G1CollectedHeap::print_hrm_post_compaction() {
 982   if (_hr_printer.is_active()) {
 983     PostCompactionPrinterClosure cl(hr_printer());
 984     heap_region_iterate(&cl);
 985   }
 986 }
 987 
 988 void G1CollectedHeap::abort_concurrent_cycle() {
 989   // If we start the compaction before the CM threads finish
 990   // scanning the root regions we might trip them over as we'll
 991   // be moving objects / updating references. So let's wait until
 992   // they are done. By telling them to abort, they should complete
 993   // early.
 994   _cm->root_regions()->abort();
 995   _cm->root_regions()->wait_until_scan_finished();
 996 
 997   // Disable discovery and empty the discovered lists
 998   // for the CM ref processor.
 999   _ref_processor_cm->disable_discovery();
1000   _ref_processor_cm->abandon_partial_discovery();
1001   _ref_processor_cm->verify_no_references_recorded();
1002 
1003   // Abandon current iterations of concurrent marking and concurrent
1004   // refinement, if any are in progress.
1005   concurrent_mark()->concurrent_cycle_abort();
1006 }
1007 
1008 void G1CollectedHeap::prepare_heap_for_full_collection() {
1009   // Make sure we'll choose a new allocation region afterwards.
1010   _allocator->release_mutator_alloc_regions();
1011   _allocator->abandon_gc_alloc_regions();
1012 
1013   // We may have added regions to the current incremental collection
1014   // set between the last GC or pause and now. We need to clear the
1015   // incremental collection set and then start rebuilding it afresh
1016   // after this full GC.
1017   abandon_collection_set(collection_set());
1018 
1019   tear_down_region_sets(false /* free_list_only */);
1020 
1021   hrm()->prepare_for_full_collection_start();
1022 }
1023 
1024 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1025   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1026   assert_used_and_recalculate_used_equal(this);
1027   _verifier->verify_region_sets_optional();
1028   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1029   _verifier->check_bitmaps("Full GC Start");
1030 }
1031 
1032 void G1CollectedHeap::prepare_heap_for_mutators() {
1033   hrm()->prepare_for_full_collection_end();
1034 
1035   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1036   ClassLoaderDataGraph::purge();
1037   MetaspaceUtils::verify_metrics();
1038 
1039   // Prepare heap for normal collections.
1040   assert(num_free_regions() == 0, "we should not have added any free regions");
1041   rebuild_region_sets(false /* free_list_only */);
1042   abort_refinement();
1043   resize_heap_if_necessary();
1044 
1045   // Rebuild the strong code root lists for each region
1046   rebuild_strong_code_roots();
1047 
1048   // Purge code root memory
1049   purge_code_root_memory();
1050 
1051   // Start a new incremental collection set for the next pause
1052   start_new_collection_set();
1053 
1054   _allocator->init_mutator_alloc_regions();
1055 
1056   // Post collection state updates.
1057   MetaspaceGC::compute_new_size();
1058 }
1059 
1060 void G1CollectedHeap::abort_refinement() {
1061   if (_hot_card_cache->use_cache()) {
1062     _hot_card_cache->reset_hot_cache();
1063   }
1064 
1065   // Discard all remembered set updates and reset refinement statistics.
1066   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1067   assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1068          "DCQS should be empty");
1069   concurrent_refine()->get_and_reset_refinement_stats();
1070 }
1071 
1072 void G1CollectedHeap::verify_after_full_collection() {
1073   _hrm->verify_optional();
1074   _verifier->verify_region_sets_optional();
1075   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1076   // Clear the previous marking bitmap, if needed for bitmap verification.
1077   // Note we cannot do this when we clear the next marking bitmap in
1078   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1079   // objects marked during a full GC against the previous bitmap.
1080   // But we need to clear it before calling check_bitmaps below since
1081   // the full GC has compacted objects and updated TAMS but not updated
1082   // the prev bitmap.
1083   if (G1VerifyBitmaps) {
1084     GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1085     _cm->clear_prev_bitmap(workers());
1086   }
1087   // This call implicitly verifies that the next bitmap is clear after Full GC.
1088   _verifier->check_bitmaps("Full GC End");
1089 
1090   // At this point there should be no regions in the
1091   // entire heap tagged as young.
1092   assert(check_young_list_empty(), "young list should be empty at this point");
1093 
1094   // Note: since we've just done a full GC, concurrent
1095   // marking is no longer active. Therefore we need not
1096   // re-enable reference discovery for the CM ref processor.
1097   // That will be done at the start of the next marking cycle.
1098   // We also know that the STW processor should no longer
1099   // discover any new references.
1100   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1101   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1102   _ref_processor_stw->verify_no_references_recorded();
1103   _ref_processor_cm->verify_no_references_recorded();
1104 }
1105 
1106 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1107   // Post collection logging.
1108   // We should do this after we potentially resize the heap so
1109   // that all the COMMIT / UNCOMMIT events are generated before
1110   // the compaction events.
1111   print_hrm_post_compaction();
1112   heap_transition->print();
1113   print_heap_after_gc();
1114   print_heap_regions();
1115 }
1116 
1117 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1118                                          bool clear_all_soft_refs) {
1119   assert_at_safepoint_on_vm_thread();
1120 
1121   if (GCLocker::check_active_before_gc()) {
1122     // Full GC was not completed.
1123     return false;
1124   }
1125 
1126   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1127       soft_ref_policy()->should_clear_all_soft_refs();
1128 
1129   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1130   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1131 
1132   collector.prepare_collection();
1133   collector.collect();
1134   collector.complete_collection();
1135 
1136   // Full collection was successfully completed.
1137   return true;
1138 }
1139 
1140 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1141   // Currently, there is no facility in the do_full_collection(bool) API to notify
1142   // the caller that the collection did not succeed (e.g., because it was locked
1143   // out by the GC locker). So, right now, we'll ignore the return value.
1144   bool dummy = do_full_collection(true,                /* explicit_gc */
1145                                   clear_all_soft_refs);
1146 }
1147 
1148 void G1CollectedHeap::resize_heap_if_necessary() {
1149   assert_at_safepoint_on_vm_thread();
1150 
1151   bool should_expand;
1152   size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
1153 
1154   if (resize_amount == 0) {
1155     return;
1156   } else if (should_expand) {
1157     expand(resize_amount, _workers);
1158   } else {
1159     shrink(resize_amount);
1160   }
1161 }
1162 
1163 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1164                                                             bool do_gc,
1165                                                             bool clear_all_soft_refs,
1166                                                             bool expect_null_mutator_alloc_region,
1167                                                             bool* gc_succeeded) {
1168   *gc_succeeded = true;
1169   // Let's attempt the allocation first.
1170   HeapWord* result =
1171     attempt_allocation_at_safepoint(word_size,
1172                                     expect_null_mutator_alloc_region);
1173   if (result != NULL) {
1174     return result;
1175   }
1176 
1177   // In a G1 heap, we're supposed to keep allocation from failing by
1178   // incremental pauses.  Therefore, at least for now, we'll favor
1179   // expansion over collection.  (This might change in the future if we can
1180   // do something smarter than full collection to satisfy a failed alloc.)
1181   result = expand_and_allocate(word_size);
1182   if (result != NULL) {
1183     return result;
1184   }
1185 
1186   if (do_gc) {
1187     // Expansion didn't work, we'll try to do a Full GC.
1188     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1189                                        clear_all_soft_refs);
1190   }
1191 
1192   return NULL;
1193 }
1194 
1195 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1196                                                      bool* succeeded) {
1197   assert_at_safepoint_on_vm_thread();
1198 
1199   // Attempts to allocate followed by Full GC.
1200   HeapWord* result =
1201     satisfy_failed_allocation_helper(word_size,
1202                                      true,  /* do_gc */
1203                                      false, /* clear_all_soft_refs */
1204                                      false, /* expect_null_mutator_alloc_region */
1205                                      succeeded);
1206 
1207   if (result != NULL || !*succeeded) {
1208     return result;
1209   }
1210 
1211   // Attempts to allocate followed by Full GC that will collect all soft references.
1212   result = satisfy_failed_allocation_helper(word_size,
1213                                             true, /* do_gc */
1214                                             true, /* clear_all_soft_refs */
1215                                             true, /* expect_null_mutator_alloc_region */
1216                                             succeeded);
1217 
1218   if (result != NULL || !*succeeded) {
1219     return result;
1220   }
1221 
1222   // Attempts to allocate, no GC
1223   result = satisfy_failed_allocation_helper(word_size,
1224                                             false, /* do_gc */
1225                                             false, /* clear_all_soft_refs */
1226                                             true,  /* expect_null_mutator_alloc_region */
1227                                             succeeded);
1228 
1229   if (result != NULL) {
1230     return result;
1231   }
1232 
1233   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1234          "Flag should have been handled and cleared prior to this point");
1235 
1236   // What else?  We might try synchronous finalization later.  If the total
1237   // space available is large enough for the allocation, then a more
1238   // complete compaction phase than we've tried so far might be
1239   // appropriate.
1240   return NULL;
1241 }
1242 
1243 // Attempting to expand the heap sufficiently
1244 // to support an allocation of the given "word_size".  If
1245 // successful, perform the allocation and return the address of the
1246 // allocated block, or else "NULL".
1247 
1248 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1249   assert_at_safepoint_on_vm_thread();
1250 
1251   _verifier->verify_region_sets_optional();
1252 
1253   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1254   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1255                             word_size * HeapWordSize);
1256 
1257 
1258   if (expand(expand_bytes, _workers)) {
1259     _hrm->verify_optional();
1260     _verifier->verify_region_sets_optional();
1261     return attempt_allocation_at_safepoint(word_size,
1262                                            false /* expect_null_mutator_alloc_region */);
1263   }
1264   return NULL;
1265 }
1266 
1267 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1268   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1269   aligned_expand_bytes = align_up(aligned_expand_bytes,
1270                                        HeapRegion::GrainBytes);
1271 
1272   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1273                             expand_bytes, aligned_expand_bytes);
1274 
1275   if (is_maximal_no_gc()) {
1276     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1277     return false;
1278   }
1279 
1280   double expand_heap_start_time_sec = os::elapsedTime();
1281   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1282   assert(regions_to_expand > 0, "Must expand by at least one region");
1283 
1284   uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1285   if (expand_time_ms != NULL) {
1286     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1287   }
1288 
1289   if (expanded_by > 0) {
1290     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1291     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1292     policy()->record_new_heap_size(num_regions());
1293   } else {
1294     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1295 
1296     // The expansion of the virtual storage space was unsuccessful.
1297     // Let's see if it was because we ran out of swap.
1298     if (G1ExitOnExpansionFailure &&
1299         _hrm->available() >= regions_to_expand) {
1300       // We had head room...
1301       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1302     }
1303   }
1304   return regions_to_expand > 0;
1305 }
1306 
1307 bool G1CollectedHeap::expand_single_region(uint node_index) {
1308   uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1309 
1310   if (expanded_by == 0) {
1311     assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1312     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1313     return false;
1314   }
1315 
1316   policy()->record_new_heap_size(num_regions());
1317   return true;
1318 }
1319 
1320 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1321   size_t aligned_shrink_bytes =
1322     ReservedSpace::page_align_size_down(shrink_bytes);
1323   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1324                                          HeapRegion::GrainBytes);
1325   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1326 
1327   uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1328   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1329 
1330   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",
1331                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1332   if (num_regions_removed > 0) {
1333     policy()->record_new_heap_size(num_regions());
1334   } else {
1335     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1336   }
1337 }
1338 
1339 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1340   _verifier->verify_region_sets_optional();
1341 
1342   // We should only reach here at the end of a Full GC or during Remark which
1343   // means we should not not be holding to any GC alloc regions. The method
1344   // below will make sure of that and do any remaining clean up.
1345   _allocator->abandon_gc_alloc_regions();
1346 
1347   // Instead of tearing down / rebuilding the free lists here, we
1348   // could instead use the remove_all_pending() method on free_list to
1349   // remove only the ones that we need to remove.
1350   tear_down_region_sets(true /* free_list_only */);
1351   shrink_helper(shrink_bytes);
1352   rebuild_region_sets(true /* free_list_only */);
1353 
1354   _hrm->verify_optional();
1355   _verifier->verify_region_sets_optional();
1356 }
1357 
1358 class OldRegionSetChecker : public HeapRegionSetChecker {
1359 public:
1360   void check_mt_safety() {
1361     // Master Old Set MT safety protocol:
1362     // (a) If we're at a safepoint, operations on the master old set
1363     // should be invoked:
1364     // - by the VM thread (which will serialize them), or
1365     // - by the GC workers while holding the FreeList_lock, if we're
1366     //   at a safepoint for an evacuation pause (this lock is taken
1367     //   anyway when an GC alloc region is retired so that a new one
1368     //   is allocated from the free list), or
1369     // - by the GC workers while holding the OldSets_lock, if we're at a
1370     //   safepoint for a cleanup pause.
1371     // (b) If we're not at a safepoint, operations on the master old set
1372     // should be invoked while holding the Heap_lock.
1373 
1374     if (SafepointSynchronize::is_at_safepoint()) {
1375       guarantee(Thread::current()->is_VM_thread() ||
1376                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1377                 "master old set MT safety protocol at a safepoint");
1378     } else {
1379       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1380     }
1381   }
1382   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1383   const char* get_description() { return "Old Regions"; }
1384 };
1385 
1386 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1387 public:
1388   void check_mt_safety() {
1389     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1390               "May only change archive regions during initialization or safepoint.");
1391   }
1392   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1393   const char* get_description() { return "Archive Regions"; }
1394 };
1395 
1396 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1397 public:
1398   void check_mt_safety() {
1399     // Humongous Set MT safety protocol:
1400     // (a) If we're at a safepoint, operations on the master humongous
1401     // set should be invoked by either the VM thread (which will
1402     // serialize them) or by the GC workers while holding the
1403     // OldSets_lock.
1404     // (b) If we're not at a safepoint, operations on the master
1405     // humongous set should be invoked while holding the Heap_lock.
1406 
1407     if (SafepointSynchronize::is_at_safepoint()) {
1408       guarantee(Thread::current()->is_VM_thread() ||
1409                 OldSets_lock->owned_by_self(),
1410                 "master humongous set MT safety protocol at a safepoint");
1411     } else {
1412       guarantee(Heap_lock->owned_by_self(),
1413                 "master humongous set MT safety protocol outside a safepoint");
1414     }
1415   }
1416   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1417   const char* get_description() { return "Humongous Regions"; }
1418 };
1419 
1420 G1CollectedHeap::G1CollectedHeap() :
1421   CollectedHeap(),
1422   _young_gen_sampling_thread(NULL),
1423   _workers(NULL),
1424   _card_table(NULL),
1425   _collection_pause_end(Ticks::now()),
1426   _soft_ref_policy(),
1427   _old_set("Old Region Set", new OldRegionSetChecker()),
1428   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1429   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1430   _bot(NULL),
1431   _listener(),
1432   _numa(G1NUMA::create()),
1433   _hrm(NULL),
1434   _allocator(NULL),
1435   _verifier(NULL),
1436   _summary_bytes_used(0),
1437   _bytes_used_during_gc(0),
1438   _archive_allocator(NULL),
1439   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1440   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1441   _expand_heap_after_alloc_failure(true),
1442   _g1mm(NULL),
1443   _humongous_reclaim_candidates(),
1444   _has_humongous_reclaim_candidates(false),
1445   _hr_printer(),
1446   _collector_state(),
1447   _old_marking_cycles_started(0),
1448   _old_marking_cycles_completed(0),
1449   _eden(),
1450   _survivor(),
1451   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1452   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1453   _policy(G1Policy::create_policy(_gc_timer_stw)),
1454   _heap_sizing_policy(NULL),
1455   _collection_set(this, _policy),
1456   _hot_card_cache(NULL),
1457   _rem_set(NULL),
1458   _cm(NULL),
1459   _cm_thread(NULL),
1460   _cr(NULL),
1461   _task_queues(NULL),
1462   _evacuation_failed(false),
1463   _evacuation_failed_info_array(NULL),
1464   _preserved_marks_set(true /* in_c_heap */),
1465 #ifndef PRODUCT
1466   _evacuation_failure_alot_for_current_gc(false),
1467   _evacuation_failure_alot_gc_number(0),
1468   _evacuation_failure_alot_count(0),
1469 #endif
1470   _ref_processor_stw(NULL),
1471   _is_alive_closure_stw(this),
1472   _is_subject_to_discovery_stw(this),
1473   _ref_processor_cm(NULL),
1474   _is_alive_closure_cm(this),
1475   _is_subject_to_discovery_cm(this),
1476   _region_attr() {
1477 
1478   _verifier = new G1HeapVerifier(this);
1479 
1480   _allocator = new G1Allocator(this);
1481 
1482   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1483 
1484   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1485 
1486   // Override the default _filler_array_max_size so that no humongous filler
1487   // objects are created.
1488   _filler_array_max_size = _humongous_object_threshold_in_words;
1489 
1490   uint n_queues = ParallelGCThreads;
1491   _task_queues = new G1ScannerTasksQueueSet(n_queues);
1492 
1493   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1494 
1495   for (uint i = 0; i < n_queues; i++) {
1496     G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1497     q->initialize();
1498     _task_queues->register_queue(i, q);
1499     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1500   }
1501 
1502   // Initialize the G1EvacuationFailureALot counters and flags.
1503   NOT_PRODUCT(reset_evacuation_should_fail();)
1504   _gc_tracer_stw->initialize();
1505 
1506   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1507 }
1508 
1509 static size_t actual_reserved_page_size(ReservedSpace rs) {
1510   size_t page_size = os::vm_page_size();
1511   if (UseLargePages) {
1512     // There are two ways to manage large page memory.
1513     // 1. OS supports committing large page memory.
1514     // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1515     //    And ReservedSpace calls it 'special'. If we failed to set 'special',
1516     //    we reserved memory without large page.
1517     if (os::can_commit_large_page_memory() || rs.special()) {
1518       // An alignment at ReservedSpace comes from preferred page size or
1519       // heap alignment, and if the alignment came from heap alignment, it could be
1520       // larger than large pages size. So need to cap with the large page size.
1521       page_size = MIN2(rs.alignment(), os::large_page_size());
1522     }
1523   }
1524 
1525   return page_size;
1526 }
1527 
1528 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1529                                                                  size_t size,
1530                                                                  size_t translation_factor) {
1531   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1532   // Allocate a new reserved space, preferring to use large pages.
1533   ReservedSpace rs(size, preferred_page_size);
1534   size_t page_size = actual_reserved_page_size(rs);
1535   G1RegionToSpaceMapper* result  =
1536     G1RegionToSpaceMapper::create_mapper(rs,
1537                                          size,
1538                                          page_size,
1539                                          HeapRegion::GrainBytes,
1540                                          translation_factor,
1541                                          mtGC);
1542 
1543   os::trace_page_sizes_for_requested_size(description,
1544                                           size,
1545                                           preferred_page_size,
1546                                           page_size,
1547                                           rs.base(),
1548                                           rs.size());
1549 
1550   return result;
1551 }
1552 
1553 jint G1CollectedHeap::initialize_concurrent_refinement() {
1554   jint ecode = JNI_OK;
1555   _cr = G1ConcurrentRefine::create(&ecode);
1556   return ecode;
1557 }
1558 
1559 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1560   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1561   if (_young_gen_sampling_thread->osthread() == NULL) {
1562     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1563     return JNI_ENOMEM;
1564   }
1565   return JNI_OK;
1566 }
1567 
1568 jint G1CollectedHeap::initialize() {
1569 
1570   // Necessary to satisfy locking discipline assertions.
1571 
1572   MutexLocker x(Heap_lock);
1573 
1574   // While there are no constraints in the GC code that HeapWordSize
1575   // be any particular value, there are multiple other areas in the
1576   // system which believe this to be true (e.g. oop->object_size in some
1577   // cases incorrectly returns the size in wordSize units rather than
1578   // HeapWordSize).
1579   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1580 
1581   size_t init_byte_size = InitialHeapSize;
1582   size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1583 
1584   // Ensure that the sizes are properly aligned.
1585   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1586   Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1587   Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1588 
1589   // Reserve the maximum.
1590 
1591   // When compressed oops are enabled, the preferred heap base
1592   // is calculated by subtracting the requested size from the
1593   // 32Gb boundary and using the result as the base address for
1594   // heap reservation. If the requested size is not aligned to
1595   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1596   // into the ReservedHeapSpace constructor) then the actual
1597   // base of the reserved heap may end up differing from the
1598   // address that was requested (i.e. the preferred heap base).
1599   // If this happens then we could end up using a non-optimal
1600   // compressed oops mode.
1601 
1602   ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1603                                                      HeapAlignment);
1604 
1605   initialize_reserved_region(heap_rs);
1606 
1607   // Create the barrier set for the entire reserved region.
1608   G1CardTable* ct = new G1CardTable(heap_rs.region());
1609   ct->initialize();
1610   G1BarrierSet* bs = new G1BarrierSet(ct);
1611   bs->initialize();
1612   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1613   BarrierSet::set_barrier_set(bs);
1614   _card_table = ct;
1615 
1616   {
1617     G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1618     satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1619     satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1620   }
1621 
1622   // Create the hot card cache.
1623   _hot_card_cache = new G1HotCardCache(this);
1624 
1625   // Carve out the G1 part of the heap.
1626   ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1627   size_t page_size = actual_reserved_page_size(heap_rs);
1628   G1RegionToSpaceMapper* heap_storage =
1629     G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1630                                               g1_rs.size(),
1631                                               page_size,
1632                                               HeapRegion::GrainBytes,
1633                                               1,
1634                                               mtJavaHeap);
1635   if(heap_storage == NULL) {
1636     vm_shutdown_during_initialization("Could not initialize G1 heap");
1637     return JNI_ERR;
1638   }
1639 
1640   os::trace_page_sizes("Heap",
1641                        MinHeapSize,
1642                        reserved_byte_size,
1643                        page_size,
1644                        heap_rs.base(),
1645                        heap_rs.size());
1646   heap_storage->set_mapping_changed_listener(&_listener);
1647 
1648   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1649   G1RegionToSpaceMapper* bot_storage =
1650     create_aux_memory_mapper("Block Offset Table",
1651                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1652                              G1BlockOffsetTable::heap_map_factor());
1653 
1654   G1RegionToSpaceMapper* cardtable_storage =
1655     create_aux_memory_mapper("Card Table",
1656                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1657                              G1CardTable::heap_map_factor());
1658 
1659   G1RegionToSpaceMapper* card_counts_storage =
1660     create_aux_memory_mapper("Card Counts Table",
1661                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1662                              G1CardCounts::heap_map_factor());
1663 
1664   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1665   G1RegionToSpaceMapper* prev_bitmap_storage =
1666     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1667   G1RegionToSpaceMapper* next_bitmap_storage =
1668     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1669 
1670   _hrm = HeapRegionManager::create_manager(this);
1671 
1672   _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1673   _card_table->initialize(cardtable_storage);
1674 
1675   // Do later initialization work for concurrent refinement.
1676   _hot_card_cache->initialize(card_counts_storage);
1677 
1678   // 6843694 - ensure that the maximum region index can fit
1679   // in the remembered set structures.
1680   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1681   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1682 
1683   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1684   // start within the first card.
1685   guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1686   // Also create a G1 rem set.
1687   _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1688   _rem_set->initialize(max_reserved_capacity(), max_regions());
1689 
1690   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1691   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1692   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1693             "too many cards per region");
1694 
1695   FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1696 
1697   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1698 
1699   {
1700     HeapWord* start = _hrm->reserved().start();
1701     HeapWord* end = _hrm->reserved().end();
1702     size_t granularity = HeapRegion::GrainBytes;
1703 
1704     _region_attr.initialize(start, end, granularity);
1705     _humongous_reclaim_candidates.initialize(start, end, granularity);
1706   }
1707 
1708   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1709                           true /* are_GC_task_threads */,
1710                           false /* are_ConcurrentGC_threads */);
1711   if (_workers == NULL) {
1712     return JNI_ENOMEM;
1713   }
1714   _workers->initialize_workers();
1715 
1716   _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1717 
1718   // Create the G1ConcurrentMark data structure and thread.
1719   // (Must do this late, so that "max_regions" is defined.)
1720   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1721   _cm_thread = _cm->cm_thread();
1722 
1723   // Now expand into the initial heap size.
1724   if (!expand(init_byte_size, _workers)) {
1725     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1726     return JNI_ENOMEM;
1727   }
1728 
1729   // Perform any initialization actions delegated to the policy.
1730   policy()->init(this, &_collection_set);
1731 
1732   jint ecode = initialize_concurrent_refinement();
1733   if (ecode != JNI_OK) {
1734     return ecode;
1735   }
1736 
1737   ecode = initialize_young_gen_sampling_thread();
1738   if (ecode != JNI_OK) {
1739     return ecode;
1740   }
1741 
1742   {
1743     G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1744     dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1745     dcqs.set_max_cards(concurrent_refine()->red_zone());
1746   }
1747 
1748   // Here we allocate the dummy HeapRegion that is required by the
1749   // G1AllocRegion class.
1750   HeapRegion* dummy_region = _hrm->get_dummy_region();
1751 
1752   // We'll re-use the same region whether the alloc region will
1753   // require BOT updates or not and, if it doesn't, then a non-young
1754   // region will complain that it cannot support allocations without
1755   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1756   dummy_region->set_eden();
1757   // Make sure it's full.
1758   dummy_region->set_top(dummy_region->end());
1759   G1AllocRegion::setup(this, dummy_region);
1760 
1761   _allocator->init_mutator_alloc_regions();
1762 
1763   // Do create of the monitoring and management support so that
1764   // values in the heap have been properly initialized.
1765   _g1mm = new G1MonitoringSupport(this);
1766 
1767   G1StringDedup::initialize();
1768 
1769   _preserved_marks_set.init(ParallelGCThreads);
1770 
1771   _collection_set.initialize(max_regions());
1772 
1773   G1InitLogger::print();
1774 
1775   return JNI_OK;
1776 }
1777 
1778 void G1CollectedHeap::stop() {
1779   // Stop all concurrent threads. We do this to make sure these threads
1780   // do not continue to execute and access resources (e.g. logging)
1781   // that are destroyed during shutdown.
1782   _cr->stop();
1783   _young_gen_sampling_thread->stop();
1784   _cm_thread->stop();
1785   if (G1StringDedup::is_enabled()) {
1786     G1StringDedup::stop();
1787   }
1788 }
1789 
1790 void G1CollectedHeap::safepoint_synchronize_begin() {
1791   SuspendibleThreadSet::synchronize();
1792 }
1793 
1794 void G1CollectedHeap::safepoint_synchronize_end() {
1795   SuspendibleThreadSet::desynchronize();
1796 }
1797 
1798 void G1CollectedHeap::post_initialize() {
1799   CollectedHeap::post_initialize();
1800   ref_processing_init();
1801 }
1802 
1803 void G1CollectedHeap::ref_processing_init() {
1804   // Reference processing in G1 currently works as follows:
1805   //
1806   // * There are two reference processor instances. One is
1807   //   used to record and process discovered references
1808   //   during concurrent marking; the other is used to
1809   //   record and process references during STW pauses
1810   //   (both full and incremental).
1811   // * Both ref processors need to 'span' the entire heap as
1812   //   the regions in the collection set may be dotted around.
1813   //
1814   // * For the concurrent marking ref processor:
1815   //   * Reference discovery is enabled at concurrent start.
1816   //   * Reference discovery is disabled and the discovered
1817   //     references processed etc during remarking.
1818   //   * Reference discovery is MT (see below).
1819   //   * Reference discovery requires a barrier (see below).
1820   //   * Reference processing may or may not be MT
1821   //     (depending on the value of ParallelRefProcEnabled
1822   //     and ParallelGCThreads).
1823   //   * A full GC disables reference discovery by the CM
1824   //     ref processor and abandons any entries on it's
1825   //     discovered lists.
1826   //
1827   // * For the STW processor:
1828   //   * Non MT discovery is enabled at the start of a full GC.
1829   //   * Processing and enqueueing during a full GC is non-MT.
1830   //   * During a full GC, references are processed after marking.
1831   //
1832   //   * Discovery (may or may not be MT) is enabled at the start
1833   //     of an incremental evacuation pause.
1834   //   * References are processed near the end of a STW evacuation pause.
1835   //   * For both types of GC:
1836   //     * Discovery is atomic - i.e. not concurrent.
1837   //     * Reference discovery will not need a barrier.
1838 
1839   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1840 
1841   // Concurrent Mark ref processor
1842   _ref_processor_cm =
1843     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1844                            mt_processing,                                  // mt processing
1845                            ParallelGCThreads,                              // degree of mt processing
1846                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1847                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1848                            false,                                          // Reference discovery is not atomic
1849                            &_is_alive_closure_cm,                          // is alive closure
1850                            true);                                          // allow changes to number of processing threads
1851 
1852   // STW ref processor
1853   _ref_processor_stw =
1854     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1855                            mt_processing,                        // mt processing
1856                            ParallelGCThreads,                    // degree of mt processing
1857                            (ParallelGCThreads > 1),              // mt discovery
1858                            ParallelGCThreads,                    // degree of mt discovery
1859                            true,                                 // Reference discovery is atomic
1860                            &_is_alive_closure_stw,               // is alive closure
1861                            true);                                // allow changes to number of processing threads
1862 }
1863 
1864 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1865   return &_soft_ref_policy;
1866 }
1867 
1868 size_t G1CollectedHeap::capacity() const {
1869   return _hrm->length() * HeapRegion::GrainBytes;
1870 }
1871 
1872 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1873   return _hrm->total_free_bytes();
1874 }
1875 
1876 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1877   _hot_card_cache->drain(cl, worker_id);
1878 }
1879 
1880 // Computes the sum of the storage used by the various regions.
1881 size_t G1CollectedHeap::used() const {
1882   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1883   if (_archive_allocator != NULL) {
1884     result += _archive_allocator->used();
1885   }
1886   return result;
1887 }
1888 
1889 size_t G1CollectedHeap::used_unlocked() const {
1890   return _summary_bytes_used;
1891 }
1892 
1893 class SumUsedClosure: public HeapRegionClosure {
1894   size_t _used;
1895 public:
1896   SumUsedClosure() : _used(0) {}
1897   bool do_heap_region(HeapRegion* r) {
1898     _used += r->used();
1899     return false;
1900   }
1901   size_t result() { return _used; }
1902 };
1903 
1904 size_t G1CollectedHeap::recalculate_used() const {
1905   SumUsedClosure blk;
1906   heap_region_iterate(&blk);
1907   return blk.result();
1908 }
1909 
1910 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1911   switch (cause) {
1912     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1913     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1914     case GCCause::_wb_conc_mark:                        return true;
1915     default :                                           return false;
1916   }
1917 }
1918 
1919 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1920   switch (cause) {
1921     case GCCause::_g1_humongous_allocation: return true;
1922     case GCCause::_g1_periodic_collection:  return G1PeriodicGCInvokesConcurrent;
1923     case GCCause::_wb_breakpoint:           return true;
1924     default:                                return is_user_requested_concurrent_full_gc(cause);
1925   }
1926 }
1927 
1928 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
1929   if (policy()->force_upgrade_to_full()) {
1930     return true;
1931   } else if (should_do_concurrent_full_gc(_gc_cause)) {
1932     return false;
1933   } else if (has_regions_left_for_allocation()) {
1934     return false;
1935   } else {
1936     return true;
1937   }
1938 }
1939 
1940 #ifndef PRODUCT
1941 void G1CollectedHeap::allocate_dummy_regions() {
1942   // Let's fill up most of the region
1943   size_t word_size = HeapRegion::GrainWords - 1024;
1944   // And as a result the region we'll allocate will be humongous.
1945   guarantee(is_humongous(word_size), "sanity");
1946 
1947   // _filler_array_max_size is set to humongous object threshold
1948   // but temporarily change it to use CollectedHeap::fill_with_object().
1949   AutoModifyRestore<size_t> temporarily(_filler_array_max_size, word_size);
1950 
1951   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1952     // Let's use the existing mechanism for the allocation
1953     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1954     if (dummy_obj != NULL) {
1955       MemRegion mr(dummy_obj, word_size);
1956       CollectedHeap::fill_with_object(mr);
1957     } else {
1958       // If we can't allocate once, we probably cannot allocate
1959       // again. Let's get out of the loop.
1960       break;
1961     }
1962   }
1963 }
1964 #endif // !PRODUCT
1965 
1966 void G1CollectedHeap::increment_old_marking_cycles_started() {
1967   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1968          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1969          "Wrong marking cycle count (started: %d, completed: %d)",
1970          _old_marking_cycles_started, _old_marking_cycles_completed);
1971 
1972   _old_marking_cycles_started++;
1973 }
1974 
1975 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1976                                                              bool whole_heap_examined) {
1977   MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1978 
1979   // We assume that if concurrent == true, then the caller is a
1980   // concurrent thread that was joined the Suspendible Thread
1981   // Set. If there's ever a cheap way to check this, we should add an
1982   // assert here.
1983 
1984   // Given that this method is called at the end of a Full GC or of a
1985   // concurrent cycle, and those can be nested (i.e., a Full GC can
1986   // interrupt a concurrent cycle), the number of full collections
1987   // completed should be either one (in the case where there was no
1988   // nesting) or two (when a Full GC interrupted a concurrent cycle)
1989   // behind the number of full collections started.
1990 
1991   // This is the case for the inner caller, i.e. a Full GC.
1992   assert(concurrent ||
1993          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1994          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1995          "for inner caller (Full GC): _old_marking_cycles_started = %u "
1996          "is inconsistent with _old_marking_cycles_completed = %u",
1997          _old_marking_cycles_started, _old_marking_cycles_completed);
1998 
1999   // This is the case for the outer caller, i.e. the concurrent cycle.
2000   assert(!concurrent ||
2001          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2002          "for outer caller (concurrent cycle): "
2003          "_old_marking_cycles_started = %u "
2004          "is inconsistent with _old_marking_cycles_completed = %u",
2005          _old_marking_cycles_started, _old_marking_cycles_completed);
2006 
2007   _old_marking_cycles_completed += 1;
2008   if (whole_heap_examined) {
2009     // Signal that we have completed a visit to all live objects.
2010     record_whole_heap_examined_timestamp();
2011   }
2012 
2013   // We need to clear the "in_progress" flag in the CM thread before
2014   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2015   // is set) so that if a waiter requests another System.gc() it doesn't
2016   // incorrectly see that a marking cycle is still in progress.
2017   if (concurrent) {
2018     _cm_thread->set_idle();
2019   }
2020 
2021   // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2022   // for a full GC to finish that their wait is over.
2023   ml.notify_all();
2024 }
2025 
2026 void G1CollectedHeap::collect(GCCause::Cause cause) {
2027   try_collect(cause);
2028 }
2029 
2030 // Return true if (x < y) with allowance for wraparound.
2031 static bool gc_counter_less_than(uint x, uint y) {
2032   return (x - y) > (UINT_MAX/2);
2033 }
2034 
2035 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2036 // Macro so msg printing is format-checked.
2037 #define LOG_COLLECT_CONCURRENTLY(cause, ...)                            \
2038   do {                                                                  \
2039     LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt;                   \
2040     if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) {                     \
2041       ResourceMark rm; /* For thread name. */                           \
2042       LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2043       LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2044                                        Thread::current()->name(),       \
2045                                        GCCause::to_string(cause));      \
2046       LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__);                    \
2047     }                                                                   \
2048   } while (0)
2049 
2050 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2051   LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2052 
2053 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2054                                                uint gc_counter,
2055                                                uint old_marking_started_before) {
2056   assert_heap_not_locked();
2057   assert(should_do_concurrent_full_gc(cause),
2058          "Non-concurrent cause %s", GCCause::to_string(cause));
2059 
2060   for (uint i = 1; true; ++i) {
2061     // Try to schedule concurrent start evacuation pause that will
2062     // start a concurrent cycle.
2063     LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2064     VM_G1TryInitiateConcMark op(gc_counter,
2065                                 cause,
2066                                 policy()->max_pause_time_ms());
2067     VMThread::execute(&op);
2068 
2069     // Request is trivially finished.
2070     if (cause == GCCause::_g1_periodic_collection) {
2071       LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2072       return op.gc_succeeded();
2073     }
2074 
2075     // If VMOp skipped initiating concurrent marking cycle because
2076     // we're terminating, then we're done.
2077     if (op.terminating()) {
2078       LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2079       return false;
2080     }
2081 
2082     // Lock to get consistent set of values.
2083     uint old_marking_started_after;
2084     uint old_marking_completed_after;
2085     {
2086       MutexLocker ml(Heap_lock);
2087       // Update gc_counter for retrying VMOp if needed. Captured here to be
2088       // consistent with the values we use below for termination tests.  If
2089       // a retry is needed after a possible wait, and another collection
2090       // occurs in the meantime, it will cause our retry to be skipped and
2091       // we'll recheck for termination with updated conditions from that
2092       // more recent collection.  That's what we want, rather than having
2093       // our retry possibly perform an unnecessary collection.
2094       gc_counter = total_collections();
2095       old_marking_started_after = _old_marking_cycles_started;
2096       old_marking_completed_after = _old_marking_cycles_completed;
2097     }
2098 
2099     if (cause == GCCause::_wb_breakpoint) {
2100       if (op.gc_succeeded()) {
2101         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2102         return true;
2103       }
2104       // When _wb_breakpoint there can't be another cycle or deferred.
2105       assert(!op.cycle_already_in_progress(), "invariant");
2106       assert(!op.whitebox_attached(), "invariant");
2107       // Concurrent cycle attempt might have been cancelled by some other
2108       // collection, so retry.  Unlike other cases below, we want to retry
2109       // even if cancelled by a STW full collection, because we really want
2110       // to start a concurrent cycle.
2111       if (old_marking_started_before != old_marking_started_after) {
2112         LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2113         old_marking_started_before = old_marking_started_after;
2114       }
2115     } else if (!GCCause::is_user_requested_gc(cause)) {
2116       // For an "automatic" (not user-requested) collection, we just need to
2117       // ensure that progress is made.
2118       //
2119       // Request is finished if any of
2120       // (1) the VMOp successfully performed a GC,
2121       // (2) a concurrent cycle was already in progress,
2122       // (3) whitebox is controlling concurrent cycles,
2123       // (4) a new cycle was started (by this thread or some other), or
2124       // (5) a Full GC was performed.
2125       // Cases (4) and (5) are detected together by a change to
2126       // _old_marking_cycles_started.
2127       //
2128       // Note that (1) does not imply (4).  If we're still in the mixed
2129       // phase of an earlier concurrent collection, the request to make the
2130       // collection a concurrent start won't be honored.  If we don't check for
2131       // both conditions we'll spin doing back-to-back collections.
2132       if (op.gc_succeeded() ||
2133           op.cycle_already_in_progress() ||
2134           op.whitebox_attached() ||
2135           (old_marking_started_before != old_marking_started_after)) {
2136         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2137         return true;
2138       }
2139     } else {                    // User-requested GC.
2140       // For a user-requested collection, we want to ensure that a complete
2141       // full collection has been performed before returning, but without
2142       // waiting for more than needed.
2143 
2144       // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2145       // new cycle was started.  That's good, because it's not clear what we
2146       // should do otherwise.  Trying again just does back to back GCs.
2147       // Can't wait for someone else to start a cycle.  And returning fails
2148       // to meet the goal of ensuring a full collection was performed.
2149       assert(!op.gc_succeeded() ||
2150              (old_marking_started_before != old_marking_started_after),
2151              "invariant: succeeded %s, started before %u, started after %u",
2152              BOOL_TO_STR(op.gc_succeeded()),
2153              old_marking_started_before, old_marking_started_after);
2154 
2155       // Request is finished if a full collection (concurrent or stw)
2156       // was started after this request and has completed, e.g.
2157       // started_before < completed_after.
2158       if (gc_counter_less_than(old_marking_started_before,
2159                                old_marking_completed_after)) {
2160         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2161         return true;
2162       }
2163 
2164       if (old_marking_started_after != old_marking_completed_after) {
2165         // If there is an in-progress cycle (possibly started by us), then
2166         // wait for that cycle to complete, e.g.
2167         // while completed_now < started_after.
2168         LOG_COLLECT_CONCURRENTLY(cause, "wait");
2169         MonitorLocker ml(G1OldGCCount_lock);
2170         while (gc_counter_less_than(_old_marking_cycles_completed,
2171                                     old_marking_started_after)) {
2172           ml.wait();
2173         }
2174         // Request is finished if the collection we just waited for was
2175         // started after this request.
2176         if (old_marking_started_before != old_marking_started_after) {
2177           LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2178           return true;
2179         }
2180       }
2181 
2182       // If VMOp was successful then it started a new cycle that the above
2183       // wait &etc should have recognized as finishing this request.  This
2184       // differs from a non-user-request, where gc_succeeded does not imply
2185       // a new cycle was started.
2186       assert(!op.gc_succeeded(), "invariant");
2187 
2188       if (op.cycle_already_in_progress()) {
2189         // If VMOp failed because a cycle was already in progress, it
2190         // is now complete.  But it didn't finish this user-requested
2191         // GC, so try again.
2192         LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2193         continue;
2194       } else if (op.whitebox_attached()) {
2195         // If WhiteBox wants control, wait for notification of a state
2196         // change in the controller, then try again.  Don't wait for
2197         // release of control, since collections may complete while in
2198         // control.  Note: This won't recognize a STW full collection
2199         // while waiting; we can't wait on multiple monitors.
2200         LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2201         MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2202         if (ConcurrentGCBreakpoints::is_controlled()) {
2203           ml.wait();
2204         }
2205         continue;
2206       }
2207     }
2208 
2209     // Collection failed and should be retried.
2210     assert(op.transient_failure(), "invariant");
2211 
2212     if (GCLocker::is_active_and_needs_gc()) {
2213       // If GCLocker is active, wait until clear before retrying.
2214       LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2215       GCLocker::stall_until_clear();
2216     }
2217 
2218     LOG_COLLECT_CONCURRENTLY(cause, "retry");
2219   }
2220 }
2221 
2222 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2223   assert_heap_not_locked();
2224 
2225   // Lock to get consistent set of values.
2226   uint gc_count_before;
2227   uint full_gc_count_before;
2228   uint old_marking_started_before;
2229   {
2230     MutexLocker ml(Heap_lock);
2231     gc_count_before = total_collections();
2232     full_gc_count_before = total_full_collections();
2233     old_marking_started_before = _old_marking_cycles_started;
2234   }
2235 
2236   if (should_do_concurrent_full_gc(cause)) {
2237     return try_collect_concurrently(cause,
2238                                     gc_count_before,
2239                                     old_marking_started_before);
2240   } else if (GCLocker::should_discard(cause, gc_count_before)) {
2241     // Indicate failure to be consistent with VMOp failure due to
2242     // another collection slipping in after our gc_count but before
2243     // our request is processed.
2244     return false;
2245   } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2246              DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2247 
2248     // Schedule a standard evacuation pause. We're setting word_size
2249     // to 0 which means that we are not requesting a post-GC allocation.
2250     VM_G1CollectForAllocation op(0,     /* word_size */
2251                                  gc_count_before,
2252                                  cause,
2253                                  policy()->max_pause_time_ms());
2254     VMThread::execute(&op);
2255     return op.gc_succeeded();
2256   } else {
2257     // Schedule a Full GC.
2258     VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2259     VMThread::execute(&op);
2260     return op.gc_succeeded();
2261   }
2262 }
2263 
2264 bool G1CollectedHeap::is_in(const void* p) const {
2265   if (_hrm->reserved().contains(p)) {
2266     // Given that we know that p is in the reserved space,
2267     // heap_region_containing() should successfully
2268     // return the containing region.
2269     HeapRegion* hr = heap_region_containing(p);
2270     return hr->is_in(p);
2271   } else {
2272     return false;
2273   }
2274 }
2275 
2276 #ifdef ASSERT
2277 bool G1CollectedHeap::is_in_exact(const void* p) const {
2278   bool contains = reserved_region().contains(p);
2279   bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2280   if (contains && available) {
2281     return true;
2282   } else {
2283     return false;
2284   }
2285 }
2286 #endif
2287 
2288 // Iteration functions.
2289 
2290 // Iterates an ObjectClosure over all objects within a HeapRegion.
2291 
2292 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2293   ObjectClosure* _cl;
2294 public:
2295   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2296   bool do_heap_region(HeapRegion* r) {
2297     if (!r->is_continues_humongous()) {
2298       r->object_iterate(_cl);
2299     }
2300     return false;
2301   }
2302 };
2303 
2304 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2305   IterateObjectClosureRegionClosure blk(cl);
2306   heap_region_iterate(&blk);
2307 }
2308 
2309 class G1ParallelObjectIterator : public ParallelObjectIterator {
2310 private:
2311   G1CollectedHeap*  _heap;
2312   HeapRegionClaimer _claimer;
2313 
2314 public:
2315   G1ParallelObjectIterator(uint thread_num) :
2316       _heap(G1CollectedHeap::heap()),
2317       _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2318 
2319   virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2320     _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2321   }
2322 };
2323 
2324 ParallelObjectIterator* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2325   return new G1ParallelObjectIterator(thread_num);
2326 }
2327 
2328 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2329   IterateObjectClosureRegionClosure blk(cl);
2330   heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2331 }
2332 
2333 void G1CollectedHeap::keep_alive(oop obj) {
2334   G1BarrierSet::enqueue(obj);
2335 }
2336 
2337 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2338   _hrm->iterate(cl);
2339 }
2340 
2341 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2342                                                                  HeapRegionClaimer *hrclaimer,
2343                                                                  uint worker_id) const {
2344   _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2345 }
2346 
2347 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2348                                                          HeapRegionClaimer *hrclaimer) const {
2349   _hrm->par_iterate(cl, hrclaimer, 0);
2350 }
2351 
2352 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2353   _collection_set.iterate(cl);
2354 }
2355 
2356 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2357   _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2358 }
2359 
2360 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2361   _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2362 }
2363 
2364 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2365   HeapRegion* hr = heap_region_containing(addr);
2366   return hr->block_start(addr);
2367 }
2368 
2369 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2370   HeapRegion* hr = heap_region_containing(addr);
2371   return hr->block_is_obj(addr);
2372 }
2373 
2374 bool G1CollectedHeap::supports_tlab_allocation() const {
2375   return true;
2376 }
2377 
2378 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2379   return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2380 }
2381 
2382 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2383   return _eden.length() * HeapRegion::GrainBytes;
2384 }
2385 
2386 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2387 // must be equal to the humongous object limit.
2388 size_t G1CollectedHeap::max_tlab_size() const {
2389   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2390 }
2391 
2392 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2393   return _allocator->unsafe_max_tlab_alloc();
2394 }
2395 
2396 size_t G1CollectedHeap::max_capacity() const {
2397   return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2398 }
2399 
2400 size_t G1CollectedHeap::max_reserved_capacity() const {
2401   return _hrm->max_length() * HeapRegion::GrainBytes;
2402 }
2403 
2404 void G1CollectedHeap::deduplicate_string(oop str) {
2405   assert(java_lang_String::is_instance(str), "invariant");
2406 
2407   if (G1StringDedup::is_enabled()) {
2408     G1StringDedup::deduplicate(str);
2409   }
2410 }
2411 
2412 void G1CollectedHeap::prepare_for_verify() {
2413   _verifier->prepare_for_verify();
2414 }
2415 
2416 void G1CollectedHeap::verify(VerifyOption vo) {
2417   _verifier->verify(vo);
2418 }
2419 
2420 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2421   return true;
2422 }
2423 
2424 bool G1CollectedHeap::is_heterogeneous_heap() const {
2425   return G1Arguments::is_heterogeneous_heap();
2426 }
2427 
2428 class PrintRegionClosure: public HeapRegionClosure {
2429   outputStream* _st;
2430 public:
2431   PrintRegionClosure(outputStream* st) : _st(st) {}
2432   bool do_heap_region(HeapRegion* r) {
2433     r->print_on(_st);
2434     return false;
2435   }
2436 };
2437 
2438 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2439                                        const HeapRegion* hr,
2440                                        const VerifyOption vo) const {
2441   switch (vo) {
2442   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2443   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2444   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2445   default:                            ShouldNotReachHere();
2446   }
2447   return false; // keep some compilers happy
2448 }
2449 
2450 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2451                                        const VerifyOption vo) const {
2452   switch (vo) {
2453   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2454   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2455   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2456   default:                            ShouldNotReachHere();
2457   }
2458   return false; // keep some compilers happy
2459 }
2460 
2461 void G1CollectedHeap::print_heap_regions() const {
2462   LogTarget(Trace, gc, heap, region) lt;
2463   if (lt.is_enabled()) {
2464     LogStream ls(lt);
2465     print_regions_on(&ls);
2466   }
2467 }
2468 
2469 void G1CollectedHeap::print_on(outputStream* st) const {
2470   st->print(" %-20s", "garbage-first heap");
2471   if (_hrm != NULL) {
2472     st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2473               capacity()/K, used_unlocked()/K);
2474     st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2475               p2i(_hrm->reserved().start()),
2476               p2i(_hrm->reserved().end()));
2477   }
2478   st->cr();
2479   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2480   uint young_regions = young_regions_count();
2481   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2482             (size_t) young_regions * HeapRegion::GrainBytes / K);
2483   uint survivor_regions = survivor_regions_count();
2484   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2485             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2486   st->cr();
2487   if (_numa->is_enabled()) {
2488     uint num_nodes = _numa->num_active_nodes();
2489     st->print("  remaining free region(s) on each NUMA node: ");
2490     const int* node_ids = _numa->node_ids();
2491     for (uint node_index = 0; node_index < num_nodes; node_index++) {
2492       uint num_free_regions = (_hrm != NULL ? _hrm->num_free_regions(node_index) : 0);
2493       st->print("%d=%u ", node_ids[node_index], num_free_regions);
2494     }
2495     st->cr();
2496   }
2497   MetaspaceUtils::print_on(st);
2498 }
2499 
2500 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2501   if (_hrm == NULL) {
2502     return;
2503   }
2504 
2505   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2506                "HS=humongous(starts), HC=humongous(continues), "
2507                "CS=collection set, F=free, "
2508                "OA=open archive, CA=closed archive, "
2509                "TAMS=top-at-mark-start (previous, next)");
2510   PrintRegionClosure blk(st);
2511   heap_region_iterate(&blk);
2512 }
2513 
2514 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2515   print_on(st);
2516 
2517   // Print the per-region information.
2518   if (_hrm != NULL) {
2519     st->cr();
2520     print_regions_on(st);
2521   }
2522 }
2523 
2524 void G1CollectedHeap::print_on_error(outputStream* st) const {
2525   this->CollectedHeap::print_on_error(st);
2526 
2527   if (_cm != NULL) {
2528     st->cr();
2529     _cm->print_on_error(st);
2530   }
2531 }
2532 
2533 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2534   workers()->threads_do(tc);
2535   tc->do_thread(_cm_thread);
2536   _cm->threads_do(tc);
2537   _cr->threads_do(tc);
2538   tc->do_thread(_young_gen_sampling_thread);
2539   if (G1StringDedup::is_enabled()) {
2540     G1StringDedup::threads_do(tc);
2541   }
2542 }
2543 
2544 void G1CollectedHeap::print_tracing_info() const {
2545   rem_set()->print_summary_info();
2546   concurrent_mark()->print_summary_info();
2547 }
2548 
2549 #ifndef PRODUCT
2550 // Helpful for debugging RSet issues.
2551 
2552 class PrintRSetsClosure : public HeapRegionClosure {
2553 private:
2554   const char* _msg;
2555   size_t _occupied_sum;
2556 
2557 public:
2558   bool do_heap_region(HeapRegion* r) {
2559     HeapRegionRemSet* hrrs = r->rem_set();
2560     size_t occupied = hrrs->occupied();
2561     _occupied_sum += occupied;
2562 
2563     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2564     if (occupied == 0) {
2565       tty->print_cr("  RSet is empty");
2566     } else {
2567       hrrs->print();
2568     }
2569     tty->print_cr("----------");
2570     return false;
2571   }
2572 
2573   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2574     tty->cr();
2575     tty->print_cr("========================================");
2576     tty->print_cr("%s", msg);
2577     tty->cr();
2578   }
2579 
2580   ~PrintRSetsClosure() {
2581     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2582     tty->print_cr("========================================");
2583     tty->cr();
2584   }
2585 };
2586 
2587 void G1CollectedHeap::print_cset_rsets() {
2588   PrintRSetsClosure cl("Printing CSet RSets");
2589   collection_set_iterate_all(&cl);
2590 }
2591 
2592 void G1CollectedHeap::print_all_rsets() {
2593   PrintRSetsClosure cl("Printing All RSets");;
2594   heap_region_iterate(&cl);
2595 }
2596 #endif // PRODUCT
2597 
2598 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2599   return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2600 }
2601 
2602 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2603 
2604   size_t eden_used_bytes = _eden.used_bytes();
2605   size_t survivor_used_bytes = _survivor.used_bytes();
2606   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2607 
2608   size_t eden_capacity_bytes =
2609     (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2610 
2611   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2612   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2613                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2614 }
2615 
2616 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2617   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2618                        stats->unused(), stats->used(), stats->region_end_waste(),
2619                        stats->regions_filled(), stats->direct_allocated(),
2620                        stats->failure_used(), stats->failure_waste());
2621 }
2622 
2623 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2624   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2625   gc_tracer->report_gc_heap_summary(when, heap_summary);
2626 
2627   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2628   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2629 }
2630 
2631 void G1CollectedHeap::gc_prologue(bool full) {
2632   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2633 
2634   // This summary needs to be printed before incrementing total collections.
2635   rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2636 
2637   // Update common counters.
2638   increment_total_collections(full /* full gc */);
2639   if (full || collector_state()->in_concurrent_start_gc()) {
2640     increment_old_marking_cycles_started();
2641   }
2642 
2643   // Fill TLAB's and such
2644   {
2645     Ticks start = Ticks::now();
2646     ensure_parsability(true);
2647     Tickspan dt = Ticks::now() - start;
2648     phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS);
2649   }
2650 
2651   if (!full) {
2652     // Flush dirty card queues to qset, so later phases don't need to account
2653     // for partially filled per-thread queues and such.  Not needed for full
2654     // collections, which ignore those logs.
2655     Ticks start = Ticks::now();
2656     G1BarrierSet::dirty_card_queue_set().concatenate_logs();
2657     Tickspan dt = Ticks::now() - start;
2658     phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS);
2659   }
2660 }
2661 
2662 void G1CollectedHeap::gc_epilogue(bool full) {
2663   // Update common counters.
2664   if (full) {
2665     // Update the number of full collections that have been completed.
2666     increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2667   }
2668 
2669   // We are at the end of the GC. Total collections has already been increased.
2670   rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2671 
2672   // FIXME: what is this about?
2673   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2674   // is set.
2675 #if COMPILER2_OR_JVMCI
2676   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2677 #endif
2678 
2679   double start = os::elapsedTime();
2680   resize_all_tlabs();
2681   phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2682 
2683   MemoryService::track_memory_usage();
2684   // We have just completed a GC. Update the soft reference
2685   // policy with the new heap occupancy
2686   Universe::update_heap_info_at_gc();
2687 
2688   // Print NUMA statistics.
2689   _numa->print_statistics();
2690 
2691   _collection_pause_end = Ticks::now();
2692 }
2693 
2694 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2695   LogTarget(Trace, gc, heap, verify) lt;
2696 
2697   if (lt.is_enabled()) {
2698     LogStream ls(lt);
2699     // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2700     G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2701     heap_region_iterate(&cl);
2702   }
2703 }
2704 
2705 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2706                                                uint gc_count_before,
2707                                                bool* succeeded,
2708                                                GCCause::Cause gc_cause) {
2709   assert_heap_not_locked_and_not_at_safepoint();
2710   VM_G1CollectForAllocation op(word_size,
2711                                gc_count_before,
2712                                gc_cause,
2713                                policy()->max_pause_time_ms());
2714   VMThread::execute(&op);
2715 
2716   HeapWord* result = op.result();
2717   bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2718   assert(result == NULL || ret_succeeded,
2719          "the result should be NULL if the VM did not succeed");
2720   *succeeded = ret_succeeded;
2721 
2722   assert_heap_not_locked();
2723   return result;
2724 }
2725 
2726 void G1CollectedHeap::do_concurrent_mark() {
2727   MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2728   if (!_cm_thread->in_progress()) {
2729     _cm_thread->set_started();
2730     CGC_lock->notify();
2731   }
2732 }
2733 
2734 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2735   // We don't nominate objects with many remembered set entries, on
2736   // the assumption that such objects are likely still live.
2737   HeapRegionRemSet* rem_set = r->rem_set();
2738 
2739   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2740          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2741          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2742 }
2743 
2744 #ifndef PRODUCT
2745 void G1CollectedHeap::verify_region_attr_remset_update() {
2746   class VerifyRegionAttrRemSet : public HeapRegionClosure {
2747   public:
2748     virtual bool do_heap_region(HeapRegion* r) {
2749       G1CollectedHeap* g1h = G1CollectedHeap::heap();
2750       bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2751       assert(r->rem_set()->is_tracked() == needs_remset_update,
2752              "Region %u remset tracking status (%s) different to region attribute (%s)",
2753              r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2754       return false;
2755     }
2756   } cl;
2757   heap_region_iterate(&cl);
2758 }
2759 #endif
2760 
2761 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2762   public:
2763     bool do_heap_region(HeapRegion* hr) {
2764       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2765         hr->verify_rem_set();
2766       }
2767       return false;
2768     }
2769 };
2770 
2771 uint G1CollectedHeap::num_task_queues() const {
2772   return _task_queues->size();
2773 }
2774 
2775 #if TASKQUEUE_STATS
2776 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2777   st->print_raw_cr("GC Task Stats");
2778   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2779   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2780 }
2781 
2782 void G1CollectedHeap::print_taskqueue_stats() const {
2783   if (!log_is_enabled(Trace, gc, task, stats)) {
2784     return;
2785   }
2786   Log(gc, task, stats) log;
2787   ResourceMark rm;
2788   LogStream ls(log.trace());
2789   outputStream* st = &ls;
2790 
2791   print_taskqueue_stats_hdr(st);
2792 
2793   TaskQueueStats totals;
2794   const uint n = num_task_queues();
2795   for (uint i = 0; i < n; ++i) {
2796     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2797     totals += task_queue(i)->stats;
2798   }
2799   st->print_raw("tot "); totals.print(st); st->cr();
2800 
2801   DEBUG_ONLY(totals.verify());
2802 }
2803 
2804 void G1CollectedHeap::reset_taskqueue_stats() {
2805   const uint n = num_task_queues();
2806   for (uint i = 0; i < n; ++i) {
2807     task_queue(i)->stats.reset();
2808   }
2809 }
2810 #endif // TASKQUEUE_STATS
2811 
2812 void G1CollectedHeap::wait_for_root_region_scanning() {
2813   double scan_wait_start = os::elapsedTime();
2814   // We have to wait until the CM threads finish scanning the
2815   // root regions as it's the only way to ensure that all the
2816   // objects on them have been correctly scanned before we start
2817   // moving them during the GC.
2818   bool waited = _cm->root_regions()->wait_until_scan_finished();
2819   double wait_time_ms = 0.0;
2820   if (waited) {
2821     double scan_wait_end = os::elapsedTime();
2822     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2823   }
2824   phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2825 }
2826 
2827 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2828 private:
2829   G1HRPrinter* _hr_printer;
2830 public:
2831   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2832 
2833   virtual bool do_heap_region(HeapRegion* r) {
2834     _hr_printer->cset(r);
2835     return false;
2836   }
2837 };
2838 
2839 void G1CollectedHeap::start_new_collection_set() {
2840   double start = os::elapsedTime();
2841 
2842   collection_set()->start_incremental_building();
2843 
2844   clear_region_attr();
2845 
2846   guarantee(_eden.length() == 0, "eden should have been cleared");
2847   policy()->transfer_survivors_to_cset(survivor());
2848 
2849   // We redo the verification but now wrt to the new CSet which
2850   // has just got initialized after the previous CSet was freed.
2851   _cm->verify_no_collection_set_oops();
2852 
2853   phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2854 }
2855 
2856 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2857 
2858   _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2859   evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2860                                             collection_set()->optional_region_length());
2861 
2862   _cm->verify_no_collection_set_oops();
2863 
2864   if (_hr_printer.is_active()) {
2865     G1PrintCollectionSetClosure cl(&_hr_printer);
2866     _collection_set.iterate(&cl);
2867     _collection_set.iterate_optional(&cl);
2868   }
2869 }
2870 
2871 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2872   if (collector_state()->in_concurrent_start_gc()) {
2873     return G1HeapVerifier::G1VerifyConcurrentStart;
2874   } else if (collector_state()->in_young_only_phase()) {
2875     return G1HeapVerifier::G1VerifyYoungNormal;
2876   } else {
2877     return G1HeapVerifier::G1VerifyMixed;
2878   }
2879 }
2880 
2881 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2882   if (VerifyRememberedSets) {
2883     log_info(gc, verify)("[Verifying RemSets before GC]");
2884     VerifyRegionRemSetClosure v_cl;
2885     heap_region_iterate(&v_cl);
2886   }
2887   _verifier->verify_before_gc(type);
2888   _verifier->check_bitmaps("GC Start");
2889   verify_numa_regions("GC Start");
2890 }
2891 
2892 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2893   if (VerifyRememberedSets) {
2894     log_info(gc, verify)("[Verifying RemSets after GC]");
2895     VerifyRegionRemSetClosure v_cl;
2896     heap_region_iterate(&v_cl);
2897   }
2898   _verifier->verify_after_gc(type);
2899   _verifier->check_bitmaps("GC End");
2900   verify_numa_regions("GC End");
2901 }
2902 
2903 void G1CollectedHeap::expand_heap_after_young_collection(){
2904   size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2905   if (expand_bytes > 0) {
2906     // No need for an ergo logging here,
2907     // expansion_amount() does this when it returns a value > 0.
2908     double expand_ms;
2909     if (!expand(expand_bytes, _workers, &expand_ms)) {
2910       // We failed to expand the heap. Cannot do anything about it.
2911     }
2912     phase_times()->record_expand_heap_time(expand_ms);
2913   }
2914 }
2915 
2916 const char* G1CollectedHeap::young_gc_name() const {
2917   if (collector_state()->in_concurrent_start_gc()) {
2918     return "Pause Young (Concurrent Start)";
2919   } else if (collector_state()->in_young_only_phase()) {
2920     if (collector_state()->in_young_gc_before_mixed()) {
2921       return "Pause Young (Prepare Mixed)";
2922     } else {
2923       return "Pause Young (Normal)";
2924     }
2925   } else {
2926     return "Pause Young (Mixed)";
2927   }
2928 }
2929 
2930 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2931   assert_at_safepoint_on_vm_thread();
2932   guarantee(!is_gc_active(), "collection is not reentrant");
2933 
2934   if (GCLocker::check_active_before_gc()) {
2935     return false;
2936   }
2937 
2938   do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2939   if (should_upgrade_to_full_gc(gc_cause())) {
2940     log_info(gc, ergo)("Attempting maximally compacting collection");
2941     bool result = do_full_collection(false /* explicit gc */,
2942                                      true /* clear_all_soft_refs */);
2943     // do_full_collection only fails if blocked by GC locker, but
2944     // we've already checked for that above.
2945     assert(result, "invariant");
2946   }
2947   return true;
2948 }
2949 
2950 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2951   GCIdMark gc_id_mark;
2952 
2953   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2954   ResourceMark rm;
2955 
2956   policy()->note_gc_start();
2957 
2958   _gc_timer_stw->register_gc_start();
2959   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2960 
2961   wait_for_root_region_scanning();
2962 
2963   print_heap_before_gc();
2964   print_heap_regions();
2965   trace_heap_before_gc(_gc_tracer_stw);
2966 
2967   _verifier->verify_region_sets_optional();
2968   _verifier->verify_dirty_young_regions();
2969 
2970   // We should not be doing concurrent start unless the concurrent mark thread is running
2971   if (!_cm_thread->should_terminate()) {
2972     // This call will decide whether this pause is a concurrent start
2973     // pause. If it is, in_concurrent_start_gc() will return true
2974     // for the duration of this pause.
2975     policy()->decide_on_conc_mark_initiation();
2976   }
2977 
2978   // We do not allow concurrent start to be piggy-backed on a mixed GC.
2979   assert(!collector_state()->in_concurrent_start_gc() ||
2980          collector_state()->in_young_only_phase(), "sanity");
2981   // We also do not allow mixed GCs during marking.
2982   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2983 
2984   // Record whether this pause is a concurrent start. When the current
2985   // thread has completed its logging output and it's safe to signal
2986   // the CM thread, the flag's value in the policy has been reset.
2987   bool should_start_conc_mark = collector_state()->in_concurrent_start_gc();
2988   if (should_start_conc_mark) {
2989     _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2990   }
2991 
2992   // Inner scope for scope based logging, timers, and stats collection
2993   {
2994     G1EvacuationInfo evacuation_info;
2995 
2996     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2997 
2998     GCTraceCPUTime tcpu;
2999 
3000     GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3001 
3002     uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3003                                                             workers()->active_workers(),
3004                                                             Threads::number_of_non_daemon_threads());
3005     active_workers = workers()->update_active_workers(active_workers);
3006     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3007 
3008     G1MonitoringScope ms(g1mm(),
3009                          false /* full_gc */,
3010                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3011 
3012     G1HeapTransition heap_transition(this);
3013 
3014     {
3015       IsGCActiveMark x;
3016 
3017       gc_prologue(false);
3018 
3019       G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3020       verify_before_young_collection(verify_type);
3021 
3022       {
3023         // The elapsed time induced by the start time below deliberately elides
3024         // the possible verification above.
3025         double sample_start_time_sec = os::elapsedTime();
3026 
3027         // Please see comment in g1CollectedHeap.hpp and
3028         // G1CollectedHeap::ref_processing_init() to see how
3029         // reference processing currently works in G1.
3030         _ref_processor_stw->enable_discovery();
3031 
3032         // We want to temporarily turn off discovery by the
3033         // CM ref processor, if necessary, and turn it back on
3034         // on again later if we do. Using a scoped
3035         // NoRefDiscovery object will do this.
3036         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3037 
3038         policy()->record_collection_pause_start(sample_start_time_sec);
3039 
3040         // Forget the current allocation region (we might even choose it to be part
3041         // of the collection set!).
3042         _allocator->release_mutator_alloc_regions();
3043 
3044         calculate_collection_set(evacuation_info, target_pause_time_ms);
3045 
3046         G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3047         G1ParScanThreadStateSet per_thread_states(this,
3048                                                   &rdcqs,
3049                                                   workers()->active_workers(),
3050                                                   collection_set()->young_region_length(),
3051                                                   collection_set()->optional_region_length());
3052         pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3053 
3054         // Actually do the work...
3055         evacuate_initial_collection_set(&per_thread_states);
3056 
3057         if (_collection_set.optional_region_length() != 0) {
3058           evacuate_optional_collection_set(&per_thread_states);
3059         }
3060         post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3061 
3062         start_new_collection_set();
3063 
3064         _survivor_evac_stats.adjust_desired_plab_sz();
3065         _old_evac_stats.adjust_desired_plab_sz();
3066 
3067         if (should_start_conc_mark) {
3068           // We have to do this before we notify the CM threads that
3069           // they can start working to make sure that all the
3070           // appropriate initialization is done on the CM object.
3071           concurrent_mark()->post_concurrent_start();
3072           // Note that we don't actually trigger the CM thread at
3073           // this point. We do that later when we're sure that
3074           // the current thread has completed its logging output.
3075         }
3076 
3077         allocate_dummy_regions();
3078 
3079         _allocator->init_mutator_alloc_regions();
3080 
3081         expand_heap_after_young_collection();
3082 
3083         double sample_end_time_sec = os::elapsedTime();
3084         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3085         policy()->record_collection_pause_end(pause_time_ms);
3086       }
3087 
3088       verify_after_young_collection(verify_type);
3089 
3090       gc_epilogue(false);
3091     }
3092 
3093     // Print the remainder of the GC log output.
3094     if (evacuation_failed()) {
3095       log_info(gc)("To-space exhausted");
3096     }
3097 
3098     policy()->print_phases();
3099     heap_transition.print();
3100 
3101     _hrm->verify_optional();
3102     _verifier->verify_region_sets_optional();
3103 
3104     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3105     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3106 
3107     print_heap_after_gc();
3108     print_heap_regions();
3109     trace_heap_after_gc(_gc_tracer_stw);
3110 
3111     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3112     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3113     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3114     // before any GC notifications are raised.
3115     g1mm()->update_sizes();
3116 
3117     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3118     _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3119     _gc_timer_stw->register_gc_end();
3120     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3121   }
3122   // It should now be safe to tell the concurrent mark thread to start
3123   // without its logging output interfering with the logging output
3124   // that came from the pause.
3125 
3126   if (should_start_conc_mark) {
3127     // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3128     // thread(s) could be running concurrently with us. Make sure that anything
3129     // after this point does not assume that we are the only GC thread running.
3130     // Note: of course, the actual marking work will not start until the safepoint
3131     // itself is released in SuspendibleThreadSet::desynchronize().
3132     do_concurrent_mark();
3133     ConcurrentGCBreakpoints::notify_idle_to_active();
3134   }
3135 }
3136 
3137 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3138   G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3139   workers()->run_task(&rsfp_task);
3140 }
3141 
3142 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3143   double remove_self_forwards_start = os::elapsedTime();
3144 
3145   remove_self_forwarding_pointers(rdcqs);
3146   _preserved_marks_set.restore(workers());
3147 
3148   phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3149 }
3150 
3151 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3152   if (!_evacuation_failed) {
3153     _evacuation_failed = true;
3154   }
3155 
3156   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3157   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3158 }
3159 
3160 bool G1ParEvacuateFollowersClosure::offer_termination() {
3161   EventGCPhaseParallel event;
3162   G1ParScanThreadState* const pss = par_scan_state();
3163   start_term_time();
3164   const bool res = terminator()->offer_termination();
3165   end_term_time();
3166   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3167   return res;
3168 }
3169 
3170 void G1ParEvacuateFollowersClosure::do_void() {
3171   EventGCPhaseParallel event;
3172   G1ParScanThreadState* const pss = par_scan_state();
3173   pss->trim_queue();
3174   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3175   do {
3176     EventGCPhaseParallel event;
3177     pss->steal_and_trim_queue(queues());
3178     event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3179   } while (!offer_termination());
3180 }
3181 
3182 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3183                                         bool class_unloading_occurred) {
3184   uint num_workers = workers()->active_workers();
3185   G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3186   workers()->run_task(&unlink_task);
3187 }
3188 
3189 // Clean string dedup data structures.
3190 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3191 // record the durations of the phases. Hence the almost-copy.
3192 class G1StringDedupCleaningTask : public AbstractGangTask {
3193   BoolObjectClosure* _is_alive;
3194   OopClosure* _keep_alive;
3195   G1GCPhaseTimes* _phase_times;
3196 
3197 public:
3198   G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3199                             OopClosure* keep_alive,
3200                             G1GCPhaseTimes* phase_times) :
3201     AbstractGangTask("Partial Cleaning Task"),
3202     _is_alive(is_alive),
3203     _keep_alive(keep_alive),
3204     _phase_times(phase_times)
3205   {
3206     assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3207     StringDedup::gc_prologue(true);
3208   }
3209 
3210   ~G1StringDedupCleaningTask() {
3211     StringDedup::gc_epilogue();
3212   }
3213 
3214   void work(uint worker_id) {
3215     StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3216     {
3217       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3218       StringDedupQueue::unlink_or_oops_do(&cl);
3219     }
3220     {
3221       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3222       StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3223     }
3224   }
3225 };
3226 
3227 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3228                                             OopClosure* keep_alive,
3229                                             G1GCPhaseTimes* phase_times) {
3230   G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3231   workers()->run_task(&cl);
3232 }
3233 
3234 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3235  private:
3236   G1RedirtyCardsQueueSet* _qset;
3237   G1CollectedHeap* _g1h;
3238   BufferNode* volatile _nodes;
3239 
3240   void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3241     size_t buffer_size = _qset->buffer_size();
3242     BufferNode* next = Atomic::load(&_nodes);
3243     while (next != NULL) {
3244       BufferNode* node = next;
3245       next = Atomic::cmpxchg(&_nodes, node, node->next());
3246       if (next == node) {
3247         cl->apply_to_buffer(node, buffer_size, worker_id);
3248         next = node->next();
3249       }
3250     }
3251   }
3252 
3253  public:
3254   G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3255     AbstractGangTask("Redirty Cards"),
3256     _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3257 
3258   virtual void work(uint worker_id) {
3259     G1GCPhaseTimes* p = _g1h->phase_times();
3260     G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3261 
3262     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3263     par_apply(&cl, worker_id);
3264 
3265     p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3266   }
3267 };
3268 
3269 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3270   double redirty_logged_cards_start = os::elapsedTime();
3271 
3272   G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3273   workers()->run_task(&redirty_task);
3274 
3275   G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3276   dcq.merge_bufferlists(rdcqs);
3277 
3278   phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3279 }
3280 
3281 // Weak Reference Processing support
3282 
3283 bool G1STWIsAliveClosure::do_object_b(oop p) {
3284   // An object is reachable if it is outside the collection set,
3285   // or is inside and copied.
3286   return !_g1h->is_in_cset(p) || p->is_forwarded();
3287 }
3288 
3289 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3290   assert(obj != NULL, "must not be NULL");
3291   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3292   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3293   // may falsely indicate that this is not the case here: however the collection set only
3294   // contains old regions when concurrent mark is not running.
3295   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3296 }
3297 
3298 // Non Copying Keep Alive closure
3299 class G1KeepAliveClosure: public OopClosure {
3300   G1CollectedHeap*_g1h;
3301 public:
3302   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3303   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3304   void do_oop(oop* p) {
3305     oop obj = *p;
3306     assert(obj != NULL, "the caller should have filtered out NULL values");
3307 
3308     const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3309     if (!region_attr.is_in_cset_or_humongous()) {
3310       return;
3311     }
3312     if (region_attr.is_in_cset()) {
3313       assert( obj->is_forwarded(), "invariant" );
3314       *p = obj->forwardee();
3315     } else {
3316       assert(!obj->is_forwarded(), "invariant" );
3317       assert(region_attr.is_humongous(),
3318              "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3319      _g1h->set_humongous_is_live(obj);
3320     }
3321   }
3322 };
3323 
3324 // Copying Keep Alive closure - can be called from both
3325 // serial and parallel code as long as different worker
3326 // threads utilize different G1ParScanThreadState instances
3327 // and different queues.
3328 
3329 class G1CopyingKeepAliveClosure: public OopClosure {
3330   G1CollectedHeap*         _g1h;
3331   G1ParScanThreadState*    _par_scan_state;
3332 
3333 public:
3334   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3335                             G1ParScanThreadState* pss):
3336     _g1h(g1h),
3337     _par_scan_state(pss)
3338   {}
3339 
3340   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3341   virtual void do_oop(      oop* p) { do_oop_work(p); }
3342 
3343   template <class T> void do_oop_work(T* p) {
3344     oop obj = RawAccess<>::oop_load(p);
3345 
3346     if (_g1h->is_in_cset_or_humongous(obj)) {
3347       // If the referent object has been forwarded (either copied
3348       // to a new location or to itself in the event of an
3349       // evacuation failure) then we need to update the reference
3350       // field and, if both reference and referent are in the G1
3351       // heap, update the RSet for the referent.
3352       //
3353       // If the referent has not been forwarded then we have to keep
3354       // it alive by policy. Therefore we have copy the referent.
3355       //
3356       // When the queue is drained (after each phase of reference processing)
3357       // the object and it's followers will be copied, the reference field set
3358       // to point to the new location, and the RSet updated.
3359       _par_scan_state->push_on_queue(ScannerTask(p));
3360     }
3361   }
3362 };
3363 
3364 // Serial drain queue closure. Called as the 'complete_gc'
3365 // closure for each discovered list in some of the
3366 // reference processing phases.
3367 
3368 class G1STWDrainQueueClosure: public VoidClosure {
3369 protected:
3370   G1CollectedHeap* _g1h;
3371   G1ParScanThreadState* _par_scan_state;
3372 
3373   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3374 
3375 public:
3376   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3377     _g1h(g1h),
3378     _par_scan_state(pss)
3379   { }
3380 
3381   void do_void() {
3382     G1ParScanThreadState* const pss = par_scan_state();
3383     pss->trim_queue();
3384   }
3385 };
3386 
3387 // Parallel Reference Processing closures
3388 
3389 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3390 // processing during G1 evacuation pauses.
3391 
3392 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3393 private:
3394   G1CollectedHeap*          _g1h;
3395   G1ParScanThreadStateSet*  _pss;
3396   G1ScannerTasksQueueSet*   _queues;
3397   WorkGang*                 _workers;
3398 
3399 public:
3400   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3401                            G1ParScanThreadStateSet* per_thread_states,
3402                            WorkGang* workers,
3403                            G1ScannerTasksQueueSet *task_queues) :
3404     _g1h(g1h),
3405     _pss(per_thread_states),
3406     _queues(task_queues),
3407     _workers(workers)
3408   {
3409     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3410   }
3411 
3412   // Executes the given task using concurrent marking worker threads.
3413   virtual void execute(ProcessTask& task, uint ergo_workers);
3414 };
3415 
3416 // Gang task for possibly parallel reference processing
3417 
3418 class G1STWRefProcTaskProxy: public AbstractGangTask {
3419   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3420   ProcessTask&     _proc_task;
3421   G1CollectedHeap* _g1h;
3422   G1ParScanThreadStateSet* _pss;
3423   G1ScannerTasksQueueSet* _task_queues;
3424   TaskTerminator* _terminator;
3425 
3426 public:
3427   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3428                         G1CollectedHeap* g1h,
3429                         G1ParScanThreadStateSet* per_thread_states,
3430                         G1ScannerTasksQueueSet *task_queues,
3431                         TaskTerminator* terminator) :
3432     AbstractGangTask("Process reference objects in parallel"),
3433     _proc_task(proc_task),
3434     _g1h(g1h),
3435     _pss(per_thread_states),
3436     _task_queues(task_queues),
3437     _terminator(terminator)
3438   {}
3439 
3440   virtual void work(uint worker_id) {
3441     // The reference processing task executed by a single worker.
3442     ResourceMark rm;
3443 
3444     G1STWIsAliveClosure is_alive(_g1h);
3445 
3446     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3447     pss->set_ref_discoverer(NULL);
3448 
3449     // Keep alive closure.
3450     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3451 
3452     // Complete GC closure
3453     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3454 
3455     // Call the reference processing task's work routine.
3456     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3457 
3458     // Note we cannot assert that the refs array is empty here as not all
3459     // of the processing tasks (specifically phase2 - pp2_work) execute
3460     // the complete_gc closure (which ordinarily would drain the queue) so
3461     // the queue may not be empty.
3462   }
3463 };
3464 
3465 // Driver routine for parallel reference processing.
3466 // Creates an instance of the ref processing gang
3467 // task and has the worker threads execute it.
3468 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3469   assert(_workers != NULL, "Need parallel worker threads.");
3470 
3471   assert(_workers->active_workers() >= ergo_workers,
3472          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3473          ergo_workers, _workers->active_workers());
3474   TaskTerminator terminator(ergo_workers, _queues);
3475   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3476 
3477   _workers->run_task(&proc_task_proxy, ergo_workers);
3478 }
3479 
3480 // End of weak reference support closures
3481 
3482 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3483   double ref_proc_start = os::elapsedTime();
3484 
3485   ReferenceProcessor* rp = _ref_processor_stw;
3486   assert(rp->discovery_enabled(), "should have been enabled");
3487 
3488   // Closure to test whether a referent is alive.
3489   G1STWIsAliveClosure is_alive(this);
3490 
3491   // Even when parallel reference processing is enabled, the processing
3492   // of JNI refs is serial and performed serially by the current thread
3493   // rather than by a worker. The following PSS will be used for processing
3494   // JNI refs.
3495 
3496   // Use only a single queue for this PSS.
3497   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3498   pss->set_ref_discoverer(NULL);
3499   assert(pss->queue_is_empty(), "pre-condition");
3500 
3501   // Keep alive closure.
3502   G1CopyingKeepAliveClosure keep_alive(this, pss);
3503 
3504   // Serial Complete GC closure
3505   G1STWDrainQueueClosure drain_queue(this, pss);
3506 
3507   // Setup the soft refs policy...
3508   rp->setup_policy(false);
3509 
3510   ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3511 
3512   ReferenceProcessorStats stats;
3513   if (!rp->processing_is_mt()) {
3514     // Serial reference processing...
3515     stats = rp->process_discovered_references(&is_alive,
3516                                               &keep_alive,
3517                                               &drain_queue,
3518                                               NULL,
3519                                               pt);
3520   } else {
3521     uint no_of_gc_workers = workers()->active_workers();
3522 
3523     // Parallel reference processing
3524     assert(no_of_gc_workers <= rp->max_num_queues(),
3525            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3526            no_of_gc_workers,  rp->max_num_queues());
3527 
3528     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3529     stats = rp->process_discovered_references(&is_alive,
3530                                               &keep_alive,
3531                                               &drain_queue,
3532                                               &par_task_executor,
3533                                               pt);
3534   }
3535 
3536   _gc_tracer_stw->report_gc_reference_stats(stats);
3537 
3538   // We have completed copying any necessary live referent objects.
3539   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3540 
3541   make_pending_list_reachable();
3542 
3543   assert(!rp->discovery_enabled(), "Postcondition");
3544   rp->verify_no_references_recorded();
3545 
3546   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3547   phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3548 }
3549 
3550 void G1CollectedHeap::make_pending_list_reachable() {
3551   if (collector_state()->in_concurrent_start_gc()) {
3552     oop pll_head = Universe::reference_pending_list();
3553     if (pll_head != NULL) {
3554       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3555       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3556     }
3557   }
3558 }
3559 
3560 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3561   Ticks start = Ticks::now();
3562   per_thread_states->flush();
3563   phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3564 }
3565 
3566 class G1PrepareEvacuationTask : public AbstractGangTask {
3567   class G1PrepareRegionsClosure : public HeapRegionClosure {
3568     G1CollectedHeap* _g1h;
3569     G1PrepareEvacuationTask* _parent_task;
3570     size_t _worker_humongous_total;
3571     size_t _worker_humongous_candidates;
3572 
3573     bool humongous_region_is_candidate(HeapRegion* region) const {
3574       assert(region->is_starts_humongous(), "Must start a humongous object");
3575 
3576       oop obj = oop(region->bottom());
3577 
3578       // Dead objects cannot be eager reclaim candidates. Due to class
3579       // unloading it is unsafe to query their classes so we return early.
3580       if (_g1h->is_obj_dead(obj, region)) {
3581         return false;
3582       }
3583 
3584       // If we do not have a complete remembered set for the region, then we can
3585       // not be sure that we have all references to it.
3586       if (!region->rem_set()->is_complete()) {
3587         return false;
3588       }
3589       // Candidate selection must satisfy the following constraints
3590       // while concurrent marking is in progress:
3591       //
3592       // * In order to maintain SATB invariants, an object must not be
3593       // reclaimed if it was allocated before the start of marking and
3594       // has not had its references scanned.  Such an object must have
3595       // its references (including type metadata) scanned to ensure no
3596       // live objects are missed by the marking process.  Objects
3597       // allocated after the start of concurrent marking don't need to
3598       // be scanned.
3599       //
3600       // * An object must not be reclaimed if it is on the concurrent
3601       // mark stack.  Objects allocated after the start of concurrent
3602       // marking are never pushed on the mark stack.
3603       //
3604       // Nominating only objects allocated after the start of concurrent
3605       // marking is sufficient to meet both constraints.  This may miss
3606       // some objects that satisfy the constraints, but the marking data
3607       // structures don't support efficiently performing the needed
3608       // additional tests or scrubbing of the mark stack.
3609       //
3610       // However, we presently only nominate is_typeArray() objects.
3611       // A humongous object containing references induces remembered
3612       // set entries on other regions.  In order to reclaim such an
3613       // object, those remembered sets would need to be cleaned up.
3614       //
3615       // We also treat is_typeArray() objects specially, allowing them
3616       // to be reclaimed even if allocated before the start of
3617       // concurrent mark.  For this we rely on mark stack insertion to
3618       // exclude is_typeArray() objects, preventing reclaiming an object
3619       // that is in the mark stack.  We also rely on the metadata for
3620       // such objects to be built-in and so ensured to be kept live.
3621       // Frequent allocation and drop of large binary blobs is an
3622       // important use case for eager reclaim, and this special handling
3623       // may reduce needed headroom.
3624 
3625       return obj->is_typeArray() &&
3626              _g1h->is_potential_eager_reclaim_candidate(region);
3627     }
3628 
3629   public:
3630     G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3631       _g1h(g1h),
3632       _parent_task(parent_task),
3633       _worker_humongous_total(0),
3634       _worker_humongous_candidates(0) { }
3635 
3636     ~G1PrepareRegionsClosure() {
3637       _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3638       _parent_task->add_humongous_total(_worker_humongous_total);
3639     }
3640 
3641     virtual bool do_heap_region(HeapRegion* hr) {
3642       // First prepare the region for scanning
3643       _g1h->rem_set()->prepare_region_for_scan(hr);
3644 
3645       // Now check if region is a humongous candidate
3646       if (!hr->is_starts_humongous()) {
3647         _g1h->register_region_with_region_attr(hr);
3648         return false;
3649       }
3650 
3651       uint index = hr->hrm_index();
3652       if (humongous_region_is_candidate(hr)) {
3653         _g1h->set_humongous_reclaim_candidate(index, true);
3654         _g1h->register_humongous_region_with_region_attr(index);
3655         _worker_humongous_candidates++;
3656         // We will later handle the remembered sets of these regions.
3657       } else {
3658         _g1h->set_humongous_reclaim_candidate(index, false);
3659         _g1h->register_region_with_region_attr(hr);
3660       }
3661       _worker_humongous_total++;
3662 
3663       return false;
3664     }
3665   };
3666 
3667   G1CollectedHeap* _g1h;
3668   HeapRegionClaimer _claimer;
3669   volatile size_t _humongous_total;
3670   volatile size_t _humongous_candidates;
3671 public:
3672   G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3673     AbstractGangTask("Prepare Evacuation"),
3674     _g1h(g1h),
3675     _claimer(_g1h->workers()->active_workers()),
3676     _humongous_total(0),
3677     _humongous_candidates(0) { }
3678 
3679   ~G1PrepareEvacuationTask() {
3680     _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3681   }
3682 
3683   void work(uint worker_id) {
3684     G1PrepareRegionsClosure cl(_g1h, this);
3685     _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3686   }
3687 
3688   void add_humongous_candidates(size_t candidates) {
3689     Atomic::add(&_humongous_candidates, candidates);
3690   }
3691 
3692   void add_humongous_total(size_t total) {
3693     Atomic::add(&_humongous_total, total);
3694   }
3695 
3696   size_t humongous_candidates() {
3697     return _humongous_candidates;
3698   }
3699 
3700   size_t humongous_total() {
3701     return _humongous_total;
3702   }
3703 };
3704 
3705 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3706   _bytes_used_during_gc = 0;
3707 
3708   _expand_heap_after_alloc_failure = true;
3709   _evacuation_failed = false;
3710 
3711   // Disable the hot card cache.
3712   _hot_card_cache->reset_hot_cache_claimed_index();
3713   _hot_card_cache->set_use_cache(false);
3714 
3715   // Initialize the GC alloc regions.
3716   _allocator->init_gc_alloc_regions(evacuation_info);
3717 
3718   {
3719     Ticks start = Ticks::now();
3720     rem_set()->prepare_for_scan_heap_roots();
3721     phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3722   }
3723 
3724   {
3725     G1PrepareEvacuationTask g1_prep_task(this);
3726     Tickspan task_time = run_task_timed(&g1_prep_task);
3727 
3728     phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3729                                            g1_prep_task.humongous_total(),
3730                                            g1_prep_task.humongous_candidates());
3731   }
3732 
3733   assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3734   _preserved_marks_set.assert_empty();
3735 
3736 #if COMPILER2_OR_JVMCI
3737   DerivedPointerTable::clear();
3738 #endif
3739 
3740   // Concurrent start needs claim bits to keep track of the marked-through CLDs.
3741   if (collector_state()->in_concurrent_start_gc()) {
3742     concurrent_mark()->pre_concurrent_start();
3743 
3744     double start_clear_claimed_marks = os::elapsedTime();
3745 
3746     ClassLoaderDataGraph::clear_claimed_marks();
3747 
3748     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3749     phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3750   }
3751 
3752   // Should G1EvacuationFailureALot be in effect for this GC?
3753   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3754 }
3755 
3756 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3757 protected:
3758   G1CollectedHeap* _g1h;
3759   G1ParScanThreadStateSet* _per_thread_states;
3760   G1ScannerTasksQueueSet* _task_queues;
3761   TaskTerminator _terminator;
3762   uint _num_workers;
3763 
3764   void evacuate_live_objects(G1ParScanThreadState* pss,
3765                              uint worker_id,
3766                              G1GCPhaseTimes::GCParPhases objcopy_phase,
3767                              G1GCPhaseTimes::GCParPhases termination_phase) {
3768     G1GCPhaseTimes* p = _g1h->phase_times();
3769 
3770     Ticks start = Ticks::now();
3771     G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3772     cl.do_void();
3773 
3774     assert(pss->queue_is_empty(), "should be empty");
3775 
3776     Tickspan evac_time = (Ticks::now() - start);
3777     p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3778 
3779     if (termination_phase == G1GCPhaseTimes::Termination) {
3780       p->record_time_secs(termination_phase, worker_id, cl.term_time());
3781       p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3782     } else {
3783       p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3784       p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3785     }
3786     assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3787   }
3788 
3789   virtual void start_work(uint worker_id) { }
3790 
3791   virtual void end_work(uint worker_id) { }
3792 
3793   virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3794 
3795   virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3796 
3797 public:
3798   G1EvacuateRegionsBaseTask(const char* name,
3799                             G1ParScanThreadStateSet* per_thread_states,
3800                             G1ScannerTasksQueueSet* task_queues,
3801                             uint num_workers) :
3802     AbstractGangTask(name),
3803     _g1h(G1CollectedHeap::heap()),
3804     _per_thread_states(per_thread_states),
3805     _task_queues(task_queues),
3806     _terminator(num_workers, _task_queues),
3807     _num_workers(num_workers)
3808   { }
3809 
3810   void work(uint worker_id) {
3811     start_work(worker_id);
3812 
3813     {
3814       ResourceMark rm;
3815 
3816       G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3817       pss->set_ref_discoverer(_g1h->ref_processor_stw());
3818 
3819       scan_roots(pss, worker_id);
3820       evacuate_live_objects(pss, worker_id);
3821     }
3822 
3823     end_work(worker_id);
3824   }
3825 };
3826 
3827 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3828   G1RootProcessor* _root_processor;
3829 
3830   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3831     _root_processor->evacuate_roots(pss, worker_id);
3832     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3833     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3834   }
3835 
3836   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3837     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3838   }
3839 
3840   void start_work(uint worker_id) {
3841     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3842   }
3843 
3844   void end_work(uint worker_id) {
3845     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3846   }
3847 
3848 public:
3849   G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3850                         G1ParScanThreadStateSet* per_thread_states,
3851                         G1ScannerTasksQueueSet* task_queues,
3852                         G1RootProcessor* root_processor,
3853                         uint num_workers) :
3854     G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3855     _root_processor(root_processor)
3856   { }
3857 };
3858 
3859 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3860   G1GCPhaseTimes* p = phase_times();
3861 
3862   {
3863     Ticks start = Ticks::now();
3864     rem_set()->merge_heap_roots(true /* initial_evacuation */);
3865     p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3866   }
3867 
3868   Tickspan task_time;
3869   const uint num_workers = workers()->active_workers();
3870 
3871   Ticks start_processing = Ticks::now();
3872   {
3873     G1RootProcessor root_processor(this, num_workers);
3874     G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3875     task_time = run_task_timed(&g1_par_task);
3876     // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3877     // To extract its code root fixup time we measure total time of this scope and
3878     // subtract from the time the WorkGang task took.
3879   }
3880   Tickspan total_processing = Ticks::now() - start_processing;
3881 
3882   p->record_initial_evac_time(task_time.seconds() * 1000.0);
3883   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3884 }
3885 
3886 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3887 
3888   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3889     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3890     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3891   }
3892 
3893   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3894     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3895   }
3896 
3897 public:
3898   G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3899                                 G1ScannerTasksQueueSet* queues,
3900                                 uint num_workers) :
3901     G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3902   }
3903 };
3904 
3905 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3906   class G1MarkScope : public MarkScope { };
3907 
3908   Tickspan task_time;
3909 
3910   Ticks start_processing = Ticks::now();
3911   {
3912     G1MarkScope code_mark_scope;
3913     G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3914     task_time = run_task_timed(&task);
3915     // See comment in evacuate_collection_set() for the reason of the scope.
3916   }
3917   Tickspan total_processing = Ticks::now() - start_processing;
3918 
3919   G1GCPhaseTimes* p = phase_times();
3920   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3921 }
3922 
3923 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3924   const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3925 
3926   while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3927 
3928     double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3929     double time_left_ms = MaxGCPauseMillis - time_used_ms;
3930 
3931     if (time_left_ms < 0 ||
3932         !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3933       log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3934                                 _collection_set.optional_region_length(), time_left_ms);
3935       break;
3936     }
3937 
3938     {
3939       Ticks start = Ticks::now();
3940       rem_set()->merge_heap_roots(false /* initial_evacuation */);
3941       phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3942     }
3943 
3944     {
3945       Ticks start = Ticks::now();
3946       evacuate_next_optional_regions(per_thread_states);
3947       phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3948     }
3949   }
3950 
3951   _collection_set.abandon_optional_collection_set(per_thread_states);
3952 }
3953 
3954 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3955                                                    G1RedirtyCardsQueueSet* rdcqs,
3956                                                    G1ParScanThreadStateSet* per_thread_states) {
3957   G1GCPhaseTimes* p = phase_times();
3958 
3959   rem_set()->cleanup_after_scan_heap_roots();
3960 
3961   // Process any discovered reference objects - we have
3962   // to do this _before_ we retire the GC alloc regions
3963   // as we may have to copy some 'reachable' referent
3964   // objects (and their reachable sub-graphs) that were
3965   // not copied during the pause.
3966   process_discovered_references(per_thread_states);
3967 
3968   G1STWIsAliveClosure is_alive(this);
3969   G1KeepAliveClosure keep_alive(this);
3970 
3971   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
3972 
3973   if (G1StringDedup::is_enabled()) {
3974     double string_dedup_time_ms = os::elapsedTime();
3975 
3976     string_dedup_cleaning(&is_alive, &keep_alive, p);
3977 
3978     double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3979     p->record_string_deduplication_time(string_cleanup_time_ms);
3980   }
3981 
3982   _allocator->release_gc_alloc_regions(evacuation_info);
3983 
3984   if (evacuation_failed()) {
3985     restore_after_evac_failure(rdcqs);
3986 
3987     // Reset the G1EvacuationFailureALot counters and flags
3988     NOT_PRODUCT(reset_evacuation_should_fail();)
3989 
3990     double recalculate_used_start = os::elapsedTime();
3991     set_used(recalculate_used());
3992     p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3993 
3994     if (_archive_allocator != NULL) {
3995       _archive_allocator->clear_used();
3996     }
3997     for (uint i = 0; i < ParallelGCThreads; i++) {
3998       if (_evacuation_failed_info_array[i].has_failed()) {
3999         _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4000       }
4001     }
4002   } else {
4003     // The "used" of the the collection set have already been subtracted
4004     // when they were freed.  Add in the bytes used.
4005     increase_used(_bytes_used_during_gc);
4006   }
4007 
4008   _preserved_marks_set.assert_empty();
4009 
4010   merge_per_thread_state_info(per_thread_states);
4011 
4012   // Reset and re-enable the hot card cache.
4013   // Note the counts for the cards in the regions in the
4014   // collection set are reset when the collection set is freed.
4015   _hot_card_cache->reset_hot_cache();
4016   _hot_card_cache->set_use_cache(true);
4017 
4018   purge_code_root_memory();
4019 
4020   redirty_logged_cards(rdcqs);
4021 
4022   free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4023 
4024   eagerly_reclaim_humongous_regions();
4025 
4026   record_obj_copy_mem_stats();
4027 
4028   evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4029   evacuation_info.set_bytes_used(_bytes_used_during_gc);
4030 
4031 #if COMPILER2_OR_JVMCI
4032   double start = os::elapsedTime();
4033   DerivedPointerTable::update_pointers();
4034   phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4035 #endif
4036   policy()->print_age_table();
4037 }
4038 
4039 void G1CollectedHeap::record_obj_copy_mem_stats() {
4040   policy()->old_gen_alloc_tracker()->
4041     add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4042 
4043   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4044                                                create_g1_evac_summary(&_old_evac_stats));
4045 }
4046 
4047 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4048   assert(!hr->is_free(), "the region should not be free");
4049   assert(!hr->is_empty(), "the region should not be empty");
4050   assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4051 
4052   if (G1VerifyBitmaps) {
4053     MemRegion mr(hr->bottom(), hr->end());
4054     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4055   }
4056 
4057   // Clear the card counts for this region.
4058   // Note: we only need to do this if the region is not young
4059   // (since we don't refine cards in young regions).
4060   if (!hr->is_young()) {
4061     _hot_card_cache->reset_card_counts(hr);
4062   }
4063 
4064   // Reset region metadata to allow reuse.
4065   hr->hr_clear(true /* clear_space */);
4066   _policy->remset_tracker()->update_at_free(hr);
4067 
4068   if (free_list != NULL) {
4069     free_list->add_ordered(hr);
4070   }
4071 }
4072 
4073 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4074                                             FreeRegionList* free_list) {
4075   assert(hr->is_humongous(), "this is only for humongous regions");
4076   assert(free_list != NULL, "pre-condition");
4077   hr->clear_humongous();
4078   free_region(hr, free_list);
4079 }
4080 
4081 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4082                                            const uint humongous_regions_removed) {
4083   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4084     MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4085     _old_set.bulk_remove(old_regions_removed);
4086     _humongous_set.bulk_remove(humongous_regions_removed);
4087   }
4088 
4089 }
4090 
4091 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4092   assert(list != NULL, "list can't be null");
4093   if (!list->is_empty()) {
4094     MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4095     _hrm->insert_list_into_free_list(list);
4096   }
4097 }
4098 
4099 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4100   decrease_used(bytes);
4101 }
4102 
4103 class G1FreeCollectionSetTask : public AbstractGangTask {
4104   // Helper class to keep statistics for the collection set freeing
4105   class FreeCSetStats {
4106     size_t _before_used_bytes;   // Usage in regions successfully evacutate
4107     size_t _after_used_bytes;    // Usage in regions failing evacuation
4108     size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4109     size_t _failure_used_words;  // Live size in failed regions
4110     size_t _failure_waste_words; // Wasted size in failed regions
4111     size_t _rs_length;           // Remembered set size
4112     uint _regions_freed;         // Number of regions freed
4113   public:
4114     FreeCSetStats() :
4115         _before_used_bytes(0),
4116         _after_used_bytes(0),
4117         _bytes_allocated_in_old_since_last_gc(0),
4118         _failure_used_words(0),
4119         _failure_waste_words(0),
4120         _rs_length(0),
4121         _regions_freed(0) { }
4122 
4123     void merge_stats(FreeCSetStats* other) {
4124       assert(other != NULL, "invariant");
4125       _before_used_bytes += other->_before_used_bytes;
4126       _after_used_bytes += other->_after_used_bytes;
4127       _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4128       _failure_used_words += other->_failure_used_words;
4129       _failure_waste_words += other->_failure_waste_words;
4130       _rs_length += other->_rs_length;
4131       _regions_freed += other->_regions_freed;
4132     }
4133 
4134     void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4135       evacuation_info->set_regions_freed(_regions_freed);
4136       evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4137 
4138       g1h->decrement_summary_bytes(_before_used_bytes);
4139       g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4140 
4141       G1Policy *policy = g1h->policy();
4142       policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4143       policy->record_rs_length(_rs_length);
4144       policy->cset_regions_freed();
4145     }
4146 
4147     void account_failed_region(HeapRegion* r) {
4148       size_t used_words = r->marked_bytes() / HeapWordSize;
4149       _failure_used_words += used_words;
4150       _failure_waste_words += HeapRegion::GrainWords - used_words;
4151       _after_used_bytes += r->used();
4152 
4153       // When moving a young gen region to old gen, we "allocate" that whole
4154       // region there. This is in addition to any already evacuated objects.
4155       // Notify the policy about that. Old gen regions do not cause an
4156       // additional allocation: both the objects still in the region and the
4157       // ones already moved are accounted for elsewhere.
4158       if (r->is_young()) {
4159         _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4160       }
4161     }
4162 
4163     void account_evacuated_region(HeapRegion* r) {
4164       _before_used_bytes += r->used();
4165       _regions_freed += 1;
4166     }
4167 
4168     void account_rs_length(HeapRegion* r) {
4169       _rs_length += r->rem_set()->occupied();
4170     }
4171   };
4172 
4173   // Closure applied to all regions in the collection set.
4174   class FreeCSetClosure : public HeapRegionClosure {
4175     // Helper to send JFR events for regions.
4176     class JFREventForRegion {
4177       EventGCPhaseParallel _event;
4178     public:
4179       JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4180         _event.set_gcId(GCId::current());
4181         _event.set_gcWorkerId(worker_id);
4182         if (region->is_young()) {
4183           _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4184         } else {
4185           _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4186         }
4187       }
4188 
4189       ~JFREventForRegion() {
4190         _event.commit();
4191       }
4192     };
4193 
4194     // Helper to do timing for region work.
4195     class TimerForRegion {
4196       Tickspan& _time;
4197       Ticks     _start_time;
4198     public:
4199       TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4200       ~TimerForRegion() {
4201         _time += Ticks::now() - _start_time;
4202       }
4203     };
4204 
4205     // FreeCSetClosure members
4206     G1CollectedHeap* _g1h;
4207     const size_t*    _surviving_young_words;
4208     uint             _worker_id;
4209     Tickspan         _young_time;
4210     Tickspan         _non_young_time;
4211     FreeCSetStats*   _stats;
4212 
4213     void assert_in_cset(HeapRegion* r) {
4214       assert(r->young_index_in_cset() != 0 &&
4215              (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4216              "Young index %u is wrong for region %u of type %s with %u young regions",
4217              r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4218     }
4219 
4220     void handle_evacuated_region(HeapRegion* r) {
4221       assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4222       stats()->account_evacuated_region(r);
4223 
4224       // Free the region and and its remembered set.
4225       _g1h->free_region(r, NULL);
4226     }
4227 
4228     void handle_failed_region(HeapRegion* r) {
4229       // Do some allocation statistics accounting. Regions that failed evacuation
4230       // are always made old, so there is no need to update anything in the young
4231       // gen statistics, but we need to update old gen statistics.
4232       stats()->account_failed_region(r);
4233 
4234       // Update the region state due to the failed evacuation.
4235       r->handle_evacuation_failure();
4236 
4237       // Add region to old set, need to hold lock.
4238       MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4239       _g1h->old_set_add(r);
4240     }
4241 
4242     Tickspan& timer_for_region(HeapRegion* r) {
4243       return r->is_young() ? _young_time : _non_young_time;
4244     }
4245 
4246     FreeCSetStats* stats() {
4247       return _stats;
4248     }
4249   public:
4250     FreeCSetClosure(const size_t* surviving_young_words,
4251                     uint worker_id,
4252                     FreeCSetStats* stats) :
4253         HeapRegionClosure(),
4254         _g1h(G1CollectedHeap::heap()),
4255         _surviving_young_words(surviving_young_words),
4256         _worker_id(worker_id),
4257         _young_time(),
4258         _non_young_time(),
4259         _stats(stats) { }
4260 
4261     virtual bool do_heap_region(HeapRegion* r) {
4262       assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4263       JFREventForRegion event(r, _worker_id);
4264       TimerForRegion timer(timer_for_region(r));
4265 
4266       _g1h->clear_region_attr(r);
4267       stats()->account_rs_length(r);
4268 
4269       if (r->is_young()) {
4270         assert_in_cset(r);
4271         r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4272       }
4273 
4274       if (r->evacuation_failed()) {
4275         handle_failed_region(r);
4276       } else {
4277         handle_evacuated_region(r);
4278       }
4279       assert(!_g1h->is_on_master_free_list(r), "sanity");
4280 
4281       return false;
4282     }
4283 
4284     void report_timing(Tickspan parallel_time) {
4285       G1GCPhaseTimes* pt = _g1h->phase_times();
4286       pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4287       if (_young_time.value() > 0) {
4288         pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4289       }
4290       if (_non_young_time.value() > 0) {
4291         pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4292       }
4293     }
4294   };
4295 
4296   // G1FreeCollectionSetTask members
4297   G1CollectedHeap*  _g1h;
4298   G1EvacuationInfo* _evacuation_info;
4299   FreeCSetStats*    _worker_stats;
4300   HeapRegionClaimer _claimer;
4301   const size_t*     _surviving_young_words;
4302   uint              _active_workers;
4303 
4304   FreeCSetStats* worker_stats(uint worker) {
4305     return &_worker_stats[worker];
4306   }
4307 
4308   void report_statistics() {
4309     // Merge the accounting
4310     FreeCSetStats total_stats;
4311     for (uint worker = 0; worker < _active_workers; worker++) {
4312       total_stats.merge_stats(worker_stats(worker));
4313     }
4314     total_stats.report(_g1h, _evacuation_info);
4315   }
4316 
4317 public:
4318   G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4319       AbstractGangTask("G1 Free Collection Set"),
4320       _g1h(G1CollectedHeap::heap()),
4321       _evacuation_info(evacuation_info),
4322       _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4323       _claimer(active_workers),
4324       _surviving_young_words(surviving_young_words),
4325       _active_workers(active_workers) {
4326     for (uint worker = 0; worker < active_workers; worker++) {
4327       ::new (&_worker_stats[worker]) FreeCSetStats();
4328     }
4329   }
4330 
4331   ~G1FreeCollectionSetTask() {
4332     Ticks serial_time = Ticks::now();
4333     report_statistics();
4334     for (uint worker = 0; worker < _active_workers; worker++) {
4335       _worker_stats[worker].~FreeCSetStats();
4336     }
4337     FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4338     _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4339   }
4340 
4341   virtual void work(uint worker_id) {
4342     EventGCPhaseParallel event;
4343     Ticks start = Ticks::now();
4344     FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4345     _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4346 
4347     // Report the total parallel time along with some more detailed metrics.
4348     cl.report_timing(Ticks::now() - start);
4349     event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4350   }
4351 };
4352 
4353 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4354   _eden.clear();
4355 
4356   // The free collections set is split up in two tasks, the first
4357   // frees the collection set and records what regions are free,
4358   // and the second one rebuilds the free list. This proved to be
4359   // more efficient than adding a sorted list to another.
4360 
4361   Ticks free_cset_start_time = Ticks::now();
4362   {
4363     uint const num_cs_regions = _collection_set.region_length();
4364     uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4365     G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4366 
4367     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4368                         cl.name(), num_workers, num_cs_regions, num_regions());
4369     workers()->run_task(&cl, num_workers);
4370   }
4371 
4372   Ticks free_cset_end_time = Ticks::now();
4373   phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4374 
4375   // Now rebuild the free region list.
4376   hrm()->rebuild_free_list(workers());
4377   phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4378 
4379   collection_set->clear();
4380 }
4381 
4382 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4383  private:
4384   FreeRegionList* _free_region_list;
4385   HeapRegionSet* _proxy_set;
4386   uint _humongous_objects_reclaimed;
4387   uint _humongous_regions_reclaimed;
4388   size_t _freed_bytes;
4389  public:
4390 
4391   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4392     _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4393   }
4394 
4395   virtual bool do_heap_region(HeapRegion* r) {
4396     if (!r->is_starts_humongous()) {
4397       return false;
4398     }
4399 
4400     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4401 
4402     oop obj = (oop)r->bottom();
4403     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4404 
4405     // The following checks whether the humongous object is live are sufficient.
4406     // The main additional check (in addition to having a reference from the roots
4407     // or the young gen) is whether the humongous object has a remembered set entry.
4408     //
4409     // A humongous object cannot be live if there is no remembered set for it
4410     // because:
4411     // - there can be no references from within humongous starts regions referencing
4412     // the object because we never allocate other objects into them.
4413     // (I.e. there are no intra-region references that may be missed by the
4414     // remembered set)
4415     // - as soon there is a remembered set entry to the humongous starts region
4416     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4417     // until the end of a concurrent mark.
4418     //
4419     // It is not required to check whether the object has been found dead by marking
4420     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4421     // all objects allocated during that time are considered live.
4422     // SATB marking is even more conservative than the remembered set.
4423     // So if at this point in the collection there is no remembered set entry,
4424     // nobody has a reference to it.
4425     // At the start of collection we flush all refinement logs, and remembered sets
4426     // are completely up-to-date wrt to references to the humongous object.
4427     //
4428     // Other implementation considerations:
4429     // - never consider object arrays at this time because they would pose
4430     // considerable effort for cleaning up the the remembered sets. This is
4431     // required because stale remembered sets might reference locations that
4432     // are currently allocated into.
4433     uint region_idx = r->hrm_index();
4434     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4435         !r->rem_set()->is_empty()) {
4436       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",
4437                                region_idx,
4438                                (size_t)obj->size() * HeapWordSize,
4439                                p2i(r->bottom()),
4440                                r->rem_set()->occupied(),
4441                                r->rem_set()->strong_code_roots_list_length(),
4442                                next_bitmap->is_marked(r->bottom()),
4443                                g1h->is_humongous_reclaim_candidate(region_idx),
4444                                obj->is_typeArray()
4445                               );
4446       return false;
4447     }
4448 
4449     guarantee(obj->is_typeArray(),
4450               "Only eagerly reclaiming type arrays is supported, but the object "
4451               PTR_FORMAT " is not.", p2i(r->bottom()));
4452 
4453     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",
4454                              region_idx,
4455                              (size_t)obj->size() * HeapWordSize,
4456                              p2i(r->bottom()),
4457                              r->rem_set()->occupied(),
4458                              r->rem_set()->strong_code_roots_list_length(),
4459                              next_bitmap->is_marked(r->bottom()),
4460                              g1h->is_humongous_reclaim_candidate(region_idx),
4461                              obj->is_typeArray()
4462                             );
4463 
4464     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4465     cm->humongous_object_eagerly_reclaimed(r);
4466     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4467            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4468            region_idx,
4469            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4470            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4471     _humongous_objects_reclaimed++;
4472     do {
4473       HeapRegion* next = g1h->next_region_in_humongous(r);
4474       _freed_bytes += r->used();
4475       r->set_containing_set(NULL);
4476       _humongous_regions_reclaimed++;
4477       g1h->free_humongous_region(r, _free_region_list);
4478       r = next;
4479     } while (r != NULL);
4480 
4481     return false;
4482   }
4483 
4484   uint humongous_objects_reclaimed() {
4485     return _humongous_objects_reclaimed;
4486   }
4487 
4488   uint humongous_regions_reclaimed() {
4489     return _humongous_regions_reclaimed;
4490   }
4491 
4492   size_t bytes_freed() const {
4493     return _freed_bytes;
4494   }
4495 };
4496 
4497 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4498   assert_at_safepoint_on_vm_thread();
4499 
4500   if (!G1EagerReclaimHumongousObjects ||
4501       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4502     phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4503     return;
4504   }
4505 
4506   double start_time = os::elapsedTime();
4507 
4508   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4509 
4510   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4511   heap_region_iterate(&cl);
4512 
4513   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4514 
4515   G1HRPrinter* hrp = hr_printer();
4516   if (hrp->is_active()) {
4517     FreeRegionListIterator iter(&local_cleanup_list);
4518     while (iter.more_available()) {
4519       HeapRegion* hr = iter.get_next();
4520       hrp->cleanup(hr);
4521     }
4522   }
4523 
4524   prepend_to_freelist(&local_cleanup_list);
4525   decrement_summary_bytes(cl.bytes_freed());
4526 
4527   phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4528                                                        cl.humongous_objects_reclaimed());
4529 }
4530 
4531 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4532 public:
4533   virtual bool do_heap_region(HeapRegion* r) {
4534     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4535     G1CollectedHeap::heap()->clear_region_attr(r);
4536     r->clear_young_index_in_cset();
4537     return false;
4538   }
4539 };
4540 
4541 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4542   G1AbandonCollectionSetClosure cl;
4543   collection_set_iterate_all(&cl);
4544 
4545   collection_set->clear();
4546   collection_set->stop_incremental_building();
4547 }
4548 
4549 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4550   return _allocator->is_retained_old_region(hr);
4551 }
4552 
4553 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4554   _eden.add(hr);
4555   _policy->set_region_eden(hr);
4556 }
4557 
4558 #ifdef ASSERT
4559 
4560 class NoYoungRegionsClosure: public HeapRegionClosure {
4561 private:
4562   bool _success;
4563 public:
4564   NoYoungRegionsClosure() : _success(true) { }
4565   bool do_heap_region(HeapRegion* r) {
4566     if (r->is_young()) {
4567       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4568                             p2i(r->bottom()), p2i(r->end()));
4569       _success = false;
4570     }
4571     return false;
4572   }
4573   bool success() { return _success; }
4574 };
4575 
4576 bool G1CollectedHeap::check_young_list_empty() {
4577   bool ret = (young_regions_count() == 0);
4578 
4579   NoYoungRegionsClosure closure;
4580   heap_region_iterate(&closure);
4581   ret = ret && closure.success();
4582 
4583   return ret;
4584 }
4585 
4586 #endif // ASSERT
4587 
4588 class TearDownRegionSetsClosure : public HeapRegionClosure {
4589   HeapRegionSet *_old_set;
4590 
4591 public:
4592   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4593 
4594   bool do_heap_region(HeapRegion* r) {
4595     if (r->is_old()) {
4596       _old_set->remove(r);
4597     } else if(r->is_young()) {
4598       r->uninstall_surv_rate_group();
4599     } else {
4600       // We ignore free regions, we'll empty the free list afterwards.
4601       // We ignore humongous and archive regions, we're not tearing down these
4602       // sets.
4603       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4604              "it cannot be another type");
4605     }
4606     return false;
4607   }
4608 
4609   ~TearDownRegionSetsClosure() {
4610     assert(_old_set->is_empty(), "post-condition");
4611   }
4612 };
4613 
4614 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4615   assert_at_safepoint_on_vm_thread();
4616 
4617   if (!free_list_only) {
4618     TearDownRegionSetsClosure cl(&_old_set);
4619     heap_region_iterate(&cl);
4620 
4621     // Note that emptying the _young_list is postponed and instead done as
4622     // the first step when rebuilding the regions sets again. The reason for
4623     // this is that during a full GC string deduplication needs to know if
4624     // a collected region was young or old when the full GC was initiated.
4625   }
4626   _hrm->remove_all_free_regions();
4627 }
4628 
4629 void G1CollectedHeap::increase_used(size_t bytes) {
4630   _summary_bytes_used += bytes;
4631 }
4632 
4633 void G1CollectedHeap::decrease_used(size_t bytes) {
4634   assert(_summary_bytes_used >= bytes,
4635          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4636          _summary_bytes_used, bytes);
4637   _summary_bytes_used -= bytes;
4638 }
4639 
4640 void G1CollectedHeap::set_used(size_t bytes) {
4641   _summary_bytes_used = bytes;
4642 }
4643 
4644 class RebuildRegionSetsClosure : public HeapRegionClosure {
4645 private:
4646   bool _free_list_only;
4647 
4648   HeapRegionSet* _old_set;
4649   HeapRegionManager* _hrm;
4650 
4651   size_t _total_used;
4652 
4653 public:
4654   RebuildRegionSetsClosure(bool free_list_only,
4655                            HeapRegionSet* old_set,
4656                            HeapRegionManager* hrm) :
4657     _free_list_only(free_list_only),
4658     _old_set(old_set), _hrm(hrm), _total_used(0) {
4659     assert(_hrm->num_free_regions() == 0, "pre-condition");
4660     if (!free_list_only) {
4661       assert(_old_set->is_empty(), "pre-condition");
4662     }
4663   }
4664 
4665   bool do_heap_region(HeapRegion* r) {
4666     if (r->is_empty()) {
4667       assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4668       // Add free regions to the free list
4669       r->set_free();
4670       _hrm->insert_into_free_list(r);
4671     } else if (!_free_list_only) {
4672       assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4673 
4674       if (r->is_archive() || r->is_humongous()) {
4675         // We ignore archive and humongous regions. We left these sets unchanged.
4676       } else {
4677         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4678         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4679         r->move_to_old();
4680         _old_set->add(r);
4681       }
4682       _total_used += r->used();
4683     }
4684 
4685     return false;
4686   }
4687 
4688   size_t total_used() {
4689     return _total_used;
4690   }
4691 };
4692 
4693 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4694   assert_at_safepoint_on_vm_thread();
4695 
4696   if (!free_list_only) {
4697     _eden.clear();
4698     _survivor.clear();
4699   }
4700 
4701   RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4702   heap_region_iterate(&cl);
4703 
4704   if (!free_list_only) {
4705     set_used(cl.total_used());
4706     if (_archive_allocator != NULL) {
4707       _archive_allocator->clear_used();
4708     }
4709   }
4710   assert_used_and_recalculate_used_equal(this);
4711 }
4712 
4713 // Methods for the mutator alloc region
4714 
4715 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4716                                                       bool force,
4717                                                       uint node_index) {
4718   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4719   bool should_allocate = policy()->should_allocate_mutator_region();
4720   if (force || should_allocate) {
4721     HeapRegion* new_alloc_region = new_region(word_size,
4722                                               HeapRegionType::Eden,
4723                                               false /* do_expand */,
4724                                               node_index);
4725     if (new_alloc_region != NULL) {
4726       set_region_short_lived_locked(new_alloc_region);
4727       _hr_printer.alloc(new_alloc_region, !should_allocate);
4728       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4729       _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4730       return new_alloc_region;
4731     }
4732   }
4733   return NULL;
4734 }
4735 
4736 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4737                                                   size_t allocated_bytes) {
4738   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4739   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4740 
4741   collection_set()->add_eden_region(alloc_region);
4742   increase_used(allocated_bytes);
4743   _eden.add_used_bytes(allocated_bytes);
4744   _hr_printer.retire(alloc_region);
4745 
4746   // We update the eden sizes here, when the region is retired,
4747   // instead of when it's allocated, since this is the point that its
4748   // used space has been recorded in _summary_bytes_used.
4749   g1mm()->update_eden_size();
4750 }
4751 
4752 // Methods for the GC alloc regions
4753 
4754 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4755   if (dest.is_old()) {
4756     return true;
4757   } else {
4758     return survivor_regions_count() < policy()->max_survivor_regions();
4759   }
4760 }
4761 
4762 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4763   assert(FreeList_lock->owned_by_self(), "pre-condition");
4764 
4765   if (!has_more_regions(dest)) {
4766     return NULL;
4767   }
4768 
4769   HeapRegionType type;
4770   if (dest.is_young()) {
4771     type = HeapRegionType::Survivor;
4772   } else {
4773     type = HeapRegionType::Old;
4774   }
4775 
4776   HeapRegion* new_alloc_region = new_region(word_size,
4777                                             type,
4778                                             true /* do_expand */,
4779                                             node_index);
4780 
4781   if (new_alloc_region != NULL) {
4782     if (type.is_survivor()) {
4783       new_alloc_region->set_survivor();
4784       _survivor.add(new_alloc_region);
4785       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4786     } else {
4787       new_alloc_region->set_old();
4788       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4789     }
4790     _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4791     register_region_with_region_attr(new_alloc_region);
4792     _hr_printer.alloc(new_alloc_region);
4793     return new_alloc_region;
4794   }
4795   return NULL;
4796 }
4797 
4798 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4799                                              size_t allocated_bytes,
4800                                              G1HeapRegionAttr dest) {
4801   _bytes_used_during_gc += allocated_bytes;
4802   if (dest.is_old()) {
4803     old_set_add(alloc_region);
4804   } else {
4805     assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4806     _survivor.add_used_bytes(allocated_bytes);
4807   }
4808 
4809   bool const during_im = collector_state()->in_concurrent_start_gc();
4810   if (during_im && allocated_bytes > 0) {
4811     _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4812   }
4813   _hr_printer.retire(alloc_region);
4814 }
4815 
4816 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4817   bool expanded = false;
4818   uint index = _hrm->find_highest_free(&expanded);
4819 
4820   if (index != G1_NO_HRM_INDEX) {
4821     if (expanded) {
4822       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4823                                 HeapRegion::GrainWords * HeapWordSize);
4824     }
4825     return _hrm->allocate_free_regions_starting_at(index, 1);
4826   }
4827   return NULL;
4828 }
4829 
4830 // Optimized nmethod scanning
4831 
4832 class RegisterNMethodOopClosure: public OopClosure {
4833   G1CollectedHeap* _g1h;
4834   nmethod* _nm;
4835 
4836   template <class T> void do_oop_work(T* p) {
4837     T heap_oop = RawAccess<>::oop_load(p);
4838     if (!CompressedOops::is_null(heap_oop)) {
4839       oop obj = CompressedOops::decode_not_null(heap_oop);
4840       HeapRegion* hr = _g1h->heap_region_containing(obj);
4841       assert(!hr->is_continues_humongous(),
4842              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4843              " starting at " HR_FORMAT,
4844              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4845 
4846       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4847       hr->add_strong_code_root_locked(_nm);
4848     }
4849   }
4850 
4851 public:
4852   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4853     _g1h(g1h), _nm(nm) {}
4854 
4855   void do_oop(oop* p)       { do_oop_work(p); }
4856   void do_oop(narrowOop* p) { do_oop_work(p); }
4857 };
4858 
4859 class UnregisterNMethodOopClosure: public OopClosure {
4860   G1CollectedHeap* _g1h;
4861   nmethod* _nm;
4862 
4863   template <class T> void do_oop_work(T* p) {
4864     T heap_oop = RawAccess<>::oop_load(p);
4865     if (!CompressedOops::is_null(heap_oop)) {
4866       oop obj = CompressedOops::decode_not_null(heap_oop);
4867       HeapRegion* hr = _g1h->heap_region_containing(obj);
4868       assert(!hr->is_continues_humongous(),
4869              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4870              " starting at " HR_FORMAT,
4871              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4872 
4873       hr->remove_strong_code_root(_nm);
4874     }
4875   }
4876 
4877 public:
4878   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4879     _g1h(g1h), _nm(nm) {}
4880 
4881   void do_oop(oop* p)       { do_oop_work(p); }
4882   void do_oop(narrowOop* p) { do_oop_work(p); }
4883 };
4884 
4885 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4886   guarantee(nm != NULL, "sanity");
4887   RegisterNMethodOopClosure reg_cl(this, nm);
4888   nm->oops_do(&reg_cl);
4889 }
4890 
4891 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4892   guarantee(nm != NULL, "sanity");
4893   UnregisterNMethodOopClosure reg_cl(this, nm);
4894   nm->oops_do(&reg_cl, true);
4895 }
4896 
4897 void G1CollectedHeap::purge_code_root_memory() {
4898   double purge_start = os::elapsedTime();
4899   G1CodeRootSet::purge();
4900   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4901   phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4902 }
4903 
4904 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4905   G1CollectedHeap* _g1h;
4906 
4907 public:
4908   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4909     _g1h(g1h) {}
4910 
4911   void do_code_blob(CodeBlob* cb) {
4912     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4913     if (nm == NULL) {
4914       return;
4915     }
4916 
4917     _g1h->register_nmethod(nm);
4918   }
4919 };
4920 
4921 void G1CollectedHeap::rebuild_strong_code_roots() {
4922   RebuildStrongCodeRootClosure blob_cl(this);
4923   CodeCache::blobs_do(&blob_cl);
4924 }
4925 
4926 void G1CollectedHeap::initialize_serviceability() {
4927   _g1mm->initialize_serviceability();
4928 }
4929 
4930 MemoryUsage G1CollectedHeap::memory_usage() {
4931   return _g1mm->memory_usage();
4932 }
4933 
4934 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4935   return _g1mm->memory_managers();
4936 }
4937 
4938 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4939   return _g1mm->memory_pools();
4940 }
--- EOF ---