rev 60584 : imported patch 8245511-ihop

   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_humongous_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         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 901         policy()->old_gen_alloc_tracker()->
 902           record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
 903         return result;
 904       }
 905 
 906       if (succeeded) {
 907         // We successfully scheduled a collection which failed to allocate. No
 908         // point in trying to allocate further. We'll just return NULL.
 909         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 910                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 911         return NULL;
 912       }
 913       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 914                            Thread::current()->name(), word_size);
 915     } else {
 916       // Failed to schedule a collection.
 917       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 918         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 919                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 920         return NULL;
 921       }
 922       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 923       // The GCLocker is either active or the GCLocker initiated
 924       // GC has not yet been performed. Stall until it is and
 925       // then retry the allocation.
 926       GCLocker::stall_until_clear();
 927       gclocker_retry_count += 1;
 928     }
 929 
 930 
 931     // We can reach here if we were unsuccessful in scheduling a
 932     // collection (because another thread beat us to it) or if we were
 933     // stalled due to the GC locker. In either can we should retry the
 934     // allocation attempt in case another thread successfully
 935     // performed a collection and reclaimed enough space.
 936     // Humongous object allocation always needs a lock, so we wait for the retry
 937     // in the next iteration of the loop, unlike for the regular iteration case.
 938     // Give a warning if we seem to be looping forever.
 939 
 940     if ((QueuedAllocationWarningCount > 0) &&
 941         (try_count % QueuedAllocationWarningCount == 0)) {
 942       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 943                              Thread::current()->name(), try_count, word_size);
 944     }
 945   }
 946 
 947   ShouldNotReachHere();
 948   return NULL;
 949 }
 950 
 951 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 952                                                            bool expect_null_mutator_alloc_region) {
 953   assert_at_safepoint_on_vm_thread();
 954   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 955          "the current alloc region was unexpectedly found to be non-NULL");
 956 
 957   if (!is_humongous(word_size)) {
 958     return _allocator->attempt_allocation_locked(word_size);
 959   } else {
 960     HeapWord* result = humongous_obj_allocate(word_size);
 961     if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
 962       collector_state()->set_initiate_conc_mark_if_possible(true);
 963     }
 964     return result;
 965   }
 966 
 967   ShouldNotReachHere();
 968 }
 969 
 970 class PostCompactionPrinterClosure: public HeapRegionClosure {
 971 private:
 972   G1HRPrinter* _hr_printer;
 973 public:
 974   bool do_heap_region(HeapRegion* hr) {
 975     assert(!hr->is_young(), "not expecting to find young regions");
 976     _hr_printer->post_compaction(hr);
 977     return false;
 978   }
 979 
 980   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 981     : _hr_printer(hr_printer) { }
 982 };
 983 
 984 void G1CollectedHeap::print_hrm_post_compaction() {
 985   if (_hr_printer.is_active()) {
 986     PostCompactionPrinterClosure cl(hr_printer());
 987     heap_region_iterate(&cl);
 988   }
 989 }
 990 
 991 void G1CollectedHeap::abort_concurrent_cycle() {
 992   // If we start the compaction before the CM threads finish
 993   // scanning the root regions we might trip them over as we'll
 994   // be moving objects / updating references. So let's wait until
 995   // they are done. By telling them to abort, they should complete
 996   // early.
 997   _cm->root_regions()->abort();
 998   _cm->root_regions()->wait_until_scan_finished();
 999 
1000   // Disable discovery and empty the discovered lists
1001   // for the CM ref processor.
1002   _ref_processor_cm->disable_discovery();
1003   _ref_processor_cm->abandon_partial_discovery();
1004   _ref_processor_cm->verify_no_references_recorded();
1005 
1006   // Abandon current iterations of concurrent marking and concurrent
1007   // refinement, if any are in progress.
1008   concurrent_mark()->concurrent_cycle_abort();
1009 }
1010 
1011 void G1CollectedHeap::prepare_heap_for_full_collection() {
1012   // Make sure we'll choose a new allocation region afterwards.
1013   _allocator->release_mutator_alloc_regions();
1014   _allocator->abandon_gc_alloc_regions();
1015 
1016   // We may have added regions to the current incremental collection
1017   // set between the last GC or pause and now. We need to clear the
1018   // incremental collection set and then start rebuilding it afresh
1019   // after this full GC.
1020   abandon_collection_set(collection_set());
1021 
1022   tear_down_region_sets(false /* free_list_only */);
1023 
1024   hrm()->prepare_for_full_collection_start();
1025 }
1026 
1027 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1028   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1029   assert_used_and_recalculate_used_equal(this);
1030   _verifier->verify_region_sets_optional();
1031   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1032   _verifier->check_bitmaps("Full GC Start");
1033 }
1034 
1035 void G1CollectedHeap::prepare_heap_for_mutators() {
1036   hrm()->prepare_for_full_collection_end();
1037 
1038   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1039   ClassLoaderDataGraph::purge();
1040   MetaspaceUtils::verify_metrics();
1041 
1042   // Prepare heap for normal collections.
1043   assert(num_free_regions() == 0, "we should not have added any free regions");
1044   rebuild_region_sets(false /* free_list_only */);
1045   abort_refinement();
1046   resize_heap_if_necessary();
1047 
1048   // Rebuild the strong code root lists for each region
1049   rebuild_strong_code_roots();
1050 
1051   // Purge code root memory
1052   purge_code_root_memory();
1053 
1054   // Start a new incremental collection set for the next pause
1055   start_new_collection_set();
1056 
1057   _allocator->init_mutator_alloc_regions();
1058 
1059   // Post collection state updates.
1060   MetaspaceGC::compute_new_size();
1061 }
1062 
1063 void G1CollectedHeap::abort_refinement() {
1064   if (_hot_card_cache->use_cache()) {
1065     _hot_card_cache->reset_hot_cache();
1066   }
1067 
1068   // Discard all remembered set updates and reset refinement statistics.
1069   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1070   assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1071          "DCQS should be empty");
1072   concurrent_refine()->get_and_reset_refinement_stats();
1073 }
1074 
1075 void G1CollectedHeap::verify_after_full_collection() {
1076   _hrm->verify_optional();
1077   _verifier->verify_region_sets_optional();
1078   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1079   // Clear the previous marking bitmap, if needed for bitmap verification.
1080   // Note we cannot do this when we clear the next marking bitmap in
1081   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1082   // objects marked during a full GC against the previous bitmap.
1083   // But we need to clear it before calling check_bitmaps below since
1084   // the full GC has compacted objects and updated TAMS but not updated
1085   // the prev bitmap.
1086   if (G1VerifyBitmaps) {
1087     GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1088     _cm->clear_prev_bitmap(workers());
1089   }
1090   // This call implicitly verifies that the next bitmap is clear after Full GC.
1091   _verifier->check_bitmaps("Full GC End");
1092 
1093   // At this point there should be no regions in the
1094   // entire heap tagged as young.
1095   assert(check_young_list_empty(), "young list should be empty at this point");
1096 
1097   // Note: since we've just done a full GC, concurrent
1098   // marking is no longer active. Therefore we need not
1099   // re-enable reference discovery for the CM ref processor.
1100   // That will be done at the start of the next marking cycle.
1101   // We also know that the STW processor should no longer
1102   // discover any new references.
1103   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1104   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1105   _ref_processor_stw->verify_no_references_recorded();
1106   _ref_processor_cm->verify_no_references_recorded();
1107 }
1108 
1109 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1110   // Post collection logging.
1111   // We should do this after we potentially resize the heap so
1112   // that all the COMMIT / UNCOMMIT events are generated before
1113   // the compaction events.
1114   print_hrm_post_compaction();
1115   heap_transition->print();
1116   print_heap_after_gc();
1117   print_heap_regions();
1118 }
1119 
1120 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1121                                          bool clear_all_soft_refs) {
1122   assert_at_safepoint_on_vm_thread();
1123 
1124   if (GCLocker::check_active_before_gc()) {
1125     // Full GC was not completed.
1126     return false;
1127   }
1128 
1129   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1130       soft_ref_policy()->should_clear_all_soft_refs();
1131 
1132   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1133   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1134 
1135   collector.prepare_collection();
1136   collector.collect();
1137   collector.complete_collection();
1138 
1139   // Full collection was successfully completed.
1140   return true;
1141 }
1142 
1143 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1144   // Currently, there is no facility in the do_full_collection(bool) API to notify
1145   // the caller that the collection did not succeed (e.g., because it was locked
1146   // out by the GC locker). So, right now, we'll ignore the return value.
1147   bool dummy = do_full_collection(true,                /* explicit_gc */
1148                                   clear_all_soft_refs);
1149 }
1150 
1151 void G1CollectedHeap::resize_heap_if_necessary() {
1152   assert_at_safepoint_on_vm_thread();
1153 
1154   bool should_expand;
1155   size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
1156 
1157   if (resize_amount == 0) {
1158     return;
1159   } else if (should_expand) {
1160     expand(resize_amount, _workers);
1161   } else {
1162     shrink(resize_amount);
1163   }
1164 }
1165 
1166 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1167                                                             bool do_gc,
1168                                                             bool clear_all_soft_refs,
1169                                                             bool expect_null_mutator_alloc_region,
1170                                                             bool* gc_succeeded) {
1171   *gc_succeeded = true;
1172   // Let's attempt the allocation first.
1173   HeapWord* result =
1174     attempt_allocation_at_safepoint(word_size,
1175                                     expect_null_mutator_alloc_region);
1176   if (result != NULL) {
1177     return result;
1178   }
1179 
1180   // In a G1 heap, we're supposed to keep allocation from failing by
1181   // incremental pauses.  Therefore, at least for now, we'll favor
1182   // expansion over collection.  (This might change in the future if we can
1183   // do something smarter than full collection to satisfy a failed alloc.)
1184   result = expand_and_allocate(word_size);
1185   if (result != NULL) {
1186     return result;
1187   }
1188 
1189   if (do_gc) {
1190     // Expansion didn't work, we'll try to do a Full GC.
1191     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1192                                        clear_all_soft_refs);
1193   }
1194 
1195   return NULL;
1196 }
1197 
1198 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1199                                                      bool* succeeded) {
1200   assert_at_safepoint_on_vm_thread();
1201 
1202   // Attempts to allocate followed by Full GC.
1203   HeapWord* result =
1204     satisfy_failed_allocation_helper(word_size,
1205                                      true,  /* do_gc */
1206                                      false, /* clear_all_soft_refs */
1207                                      false, /* expect_null_mutator_alloc_region */
1208                                      succeeded);
1209 
1210   if (result != NULL || !*succeeded) {
1211     return result;
1212   }
1213 
1214   // Attempts to allocate followed by Full GC that will collect all soft references.
1215   result = satisfy_failed_allocation_helper(word_size,
1216                                             true, /* do_gc */
1217                                             true, /* clear_all_soft_refs */
1218                                             true, /* expect_null_mutator_alloc_region */
1219                                             succeeded);
1220 
1221   if (result != NULL || !*succeeded) {
1222     return result;
1223   }
1224 
1225   // Attempts to allocate, no GC
1226   result = satisfy_failed_allocation_helper(word_size,
1227                                             false, /* do_gc */
1228                                             false, /* clear_all_soft_refs */
1229                                             true,  /* expect_null_mutator_alloc_region */
1230                                             succeeded);
1231 
1232   if (result != NULL) {
1233     return result;
1234   }
1235 
1236   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1237          "Flag should have been handled and cleared prior to this point");
1238 
1239   // What else?  We might try synchronous finalization later.  If the total
1240   // space available is large enough for the allocation, then a more
1241   // complete compaction phase than we've tried so far might be
1242   // appropriate.
1243   return NULL;
1244 }
1245 
1246 // Attempting to expand the heap sufficiently
1247 // to support an allocation of the given "word_size".  If
1248 // successful, perform the allocation and return the address of the
1249 // allocated block, or else "NULL".
1250 
1251 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1252   assert_at_safepoint_on_vm_thread();
1253 
1254   _verifier->verify_region_sets_optional();
1255 
1256   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1257   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1258                             word_size * HeapWordSize);
1259 
1260 
1261   if (expand(expand_bytes, _workers)) {
1262     _hrm->verify_optional();
1263     _verifier->verify_region_sets_optional();
1264     return attempt_allocation_at_safepoint(word_size,
1265                                            false /* expect_null_mutator_alloc_region */);
1266   }
1267   return NULL;
1268 }
1269 
1270 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1271   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1272   aligned_expand_bytes = align_up(aligned_expand_bytes,
1273                                        HeapRegion::GrainBytes);
1274 
1275   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1276                             expand_bytes, aligned_expand_bytes);
1277 
1278   if (is_maximal_no_gc()) {
1279     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1280     return false;
1281   }
1282 
1283   double expand_heap_start_time_sec = os::elapsedTime();
1284   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1285   assert(regions_to_expand > 0, "Must expand by at least one region");
1286 
1287   uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1288   if (expand_time_ms != NULL) {
1289     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1290   }
1291 
1292   if (expanded_by > 0) {
1293     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1294     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1295     policy()->record_new_heap_size(num_regions());
1296   } else {
1297     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1298 
1299     // The expansion of the virtual storage space was unsuccessful.
1300     // Let's see if it was because we ran out of swap.
1301     if (G1ExitOnExpansionFailure &&
1302         _hrm->available() >= regions_to_expand) {
1303       // We had head room...
1304       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1305     }
1306   }
1307   return regions_to_expand > 0;
1308 }
1309 
1310 bool G1CollectedHeap::expand_single_region(uint node_index) {
1311   uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1312 
1313   if (expanded_by == 0) {
1314     assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1315     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1316     return false;
1317   }
1318 
1319   policy()->record_new_heap_size(num_regions());
1320   return true;
1321 }
1322 
1323 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1324   size_t aligned_shrink_bytes =
1325     ReservedSpace::page_align_size_down(shrink_bytes);
1326   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1327                                          HeapRegion::GrainBytes);
1328   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1329 
1330   uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1331   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1332 
1333   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",
1334                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1335   if (num_regions_removed > 0) {
1336     policy()->record_new_heap_size(num_regions());
1337   } else {
1338     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1339   }
1340 }
1341 
1342 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1343   _verifier->verify_region_sets_optional();
1344 
1345   // We should only reach here at the end of a Full GC or during Remark which
1346   // means we should not not be holding to any GC alloc regions. The method
1347   // below will make sure of that and do any remaining clean up.
1348   _allocator->abandon_gc_alloc_regions();
1349 
1350   // Instead of tearing down / rebuilding the free lists here, we
1351   // could instead use the remove_all_pending() method on free_list to
1352   // remove only the ones that we need to remove.
1353   tear_down_region_sets(true /* free_list_only */);
1354   shrink_helper(shrink_bytes);
1355   rebuild_region_sets(true /* free_list_only */);
1356 
1357   _hrm->verify_optional();
1358   _verifier->verify_region_sets_optional();
1359 }
1360 
1361 class OldRegionSetChecker : public HeapRegionSetChecker {
1362 public:
1363   void check_mt_safety() {
1364     // Master Old Set MT safety protocol:
1365     // (a) If we're at a safepoint, operations on the master old set
1366     // should be invoked:
1367     // - by the VM thread (which will serialize them), or
1368     // - by the GC workers while holding the FreeList_lock, if we're
1369     //   at a safepoint for an evacuation pause (this lock is taken
1370     //   anyway when an GC alloc region is retired so that a new one
1371     //   is allocated from the free list), or
1372     // - by the GC workers while holding the OldSets_lock, if we're at a
1373     //   safepoint for a cleanup pause.
1374     // (b) If we're not at a safepoint, operations on the master old set
1375     // should be invoked while holding the Heap_lock.
1376 
1377     if (SafepointSynchronize::is_at_safepoint()) {
1378       guarantee(Thread::current()->is_VM_thread() ||
1379                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1380                 "master old set MT safety protocol at a safepoint");
1381     } else {
1382       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1383     }
1384   }
1385   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1386   const char* get_description() { return "Old Regions"; }
1387 };
1388 
1389 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1390 public:
1391   void check_mt_safety() {
1392     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1393               "May only change archive regions during initialization or safepoint.");
1394   }
1395   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1396   const char* get_description() { return "Archive Regions"; }
1397 };
1398 
1399 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1400 public:
1401   void check_mt_safety() {
1402     // Humongous Set MT safety protocol:
1403     // (a) If we're at a safepoint, operations on the master humongous
1404     // set should be invoked by either the VM thread (which will
1405     // serialize them) or by the GC workers while holding the
1406     // OldSets_lock.
1407     // (b) If we're not at a safepoint, operations on the master
1408     // humongous set should be invoked while holding the Heap_lock.
1409 
1410     if (SafepointSynchronize::is_at_safepoint()) {
1411       guarantee(Thread::current()->is_VM_thread() ||
1412                 OldSets_lock->owned_by_self(),
1413                 "master humongous set MT safety protocol at a safepoint");
1414     } else {
1415       guarantee(Heap_lock->owned_by_self(),
1416                 "master humongous set MT safety protocol outside a safepoint");
1417     }
1418   }
1419   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1420   const char* get_description() { return "Humongous Regions"; }
1421 };
1422 
1423 G1CollectedHeap::G1CollectedHeap() :
1424   CollectedHeap(),
1425   _young_gen_sampling_thread(NULL),
1426   _workers(NULL),
1427   _card_table(NULL),
1428   _collection_pause_end(Ticks::now()),
1429   _soft_ref_policy(),
1430   _old_set("Old Region Set", new OldRegionSetChecker()),
1431   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1432   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1433   _bot(NULL),
1434   _listener(),
1435   _numa(G1NUMA::create()),
1436   _hrm(NULL),
1437   _allocator(NULL),
1438   _verifier(NULL),
1439   _summary_bytes_used(0),
1440   _bytes_used_during_gc(0),
1441   _archive_allocator(NULL),
1442   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1443   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1444   _expand_heap_after_alloc_failure(true),
1445   _g1mm(NULL),
1446   _humongous_reclaim_candidates(),
1447   _has_humongous_reclaim_candidates(false),
1448   _hr_printer(),
1449   _collector_state(),
1450   _old_marking_cycles_started(0),
1451   _old_marking_cycles_completed(0),
1452   _eden(),
1453   _survivor(),
1454   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1455   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1456   _policy(G1Policy::create_policy(_gc_timer_stw)),
1457   _heap_sizing_policy(NULL),
1458   _collection_set(this, _policy),
1459   _hot_card_cache(NULL),
1460   _rem_set(NULL),
1461   _cm(NULL),
1462   _cm_thread(NULL),
1463   _cr(NULL),
1464   _task_queues(NULL),
1465   _evacuation_failed(false),
1466   _evacuation_failed_info_array(NULL),
1467   _preserved_marks_set(true /* in_c_heap */),
1468 #ifndef PRODUCT
1469   _evacuation_failure_alot_for_current_gc(false),
1470   _evacuation_failure_alot_gc_number(0),
1471   _evacuation_failure_alot_count(0),
1472 #endif
1473   _ref_processor_stw(NULL),
1474   _is_alive_closure_stw(this),
1475   _is_subject_to_discovery_stw(this),
1476   _ref_processor_cm(NULL),
1477   _is_alive_closure_cm(this),
1478   _is_subject_to_discovery_cm(this),
1479   _region_attr() {
1480 
1481   _verifier = new G1HeapVerifier(this);
1482 
1483   _allocator = new G1Allocator(this);
1484 
1485   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1486 
1487   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1488 
1489   // Override the default _filler_array_max_size so that no humongous filler
1490   // objects are created.
1491   _filler_array_max_size = _humongous_object_threshold_in_words;
1492 
1493   uint n_queues = ParallelGCThreads;
1494   _task_queues = new G1ScannerTasksQueueSet(n_queues);
1495 
1496   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1497 
1498   for (uint i = 0; i < n_queues; i++) {
1499     G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1500     q->initialize();
1501     _task_queues->register_queue(i, q);
1502     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1503   }
1504 
1505   // Initialize the G1EvacuationFailureALot counters and flags.
1506   NOT_PRODUCT(reset_evacuation_should_fail();)
1507   _gc_tracer_stw->initialize();
1508 
1509   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1510 }
1511 
1512 static size_t actual_reserved_page_size(ReservedSpace rs) {
1513   size_t page_size = os::vm_page_size();
1514   if (UseLargePages) {
1515     // There are two ways to manage large page memory.
1516     // 1. OS supports committing large page memory.
1517     // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1518     //    And ReservedSpace calls it 'special'. If we failed to set 'special',
1519     //    we reserved memory without large page.
1520     if (os::can_commit_large_page_memory() || rs.special()) {
1521       // An alignment at ReservedSpace comes from preferred page size or
1522       // heap alignment, and if the alignment came from heap alignment, it could be
1523       // larger than large pages size. So need to cap with the large page size.
1524       page_size = MIN2(rs.alignment(), os::large_page_size());
1525     }
1526   }
1527 
1528   return page_size;
1529 }
1530 
1531 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1532                                                                  size_t size,
1533                                                                  size_t translation_factor) {
1534   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1535   // Allocate a new reserved space, preferring to use large pages.
1536   ReservedSpace rs(size, preferred_page_size);
1537   size_t page_size = actual_reserved_page_size(rs);
1538   G1RegionToSpaceMapper* result  =
1539     G1RegionToSpaceMapper::create_mapper(rs,
1540                                          size,
1541                                          page_size,
1542                                          HeapRegion::GrainBytes,
1543                                          translation_factor,
1544                                          mtGC);
1545 
1546   os::trace_page_sizes_for_requested_size(description,
1547                                           size,
1548                                           preferred_page_size,
1549                                           page_size,
1550                                           rs.base(),
1551                                           rs.size());
1552 
1553   return result;
1554 }
1555 
1556 jint G1CollectedHeap::initialize_concurrent_refinement() {
1557   jint ecode = JNI_OK;
1558   _cr = G1ConcurrentRefine::create(&ecode);
1559   return ecode;
1560 }
1561 
1562 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1563   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1564   if (_young_gen_sampling_thread->osthread() == NULL) {
1565     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1566     return JNI_ENOMEM;
1567   }
1568   return JNI_OK;
1569 }
1570 
1571 jint G1CollectedHeap::initialize() {
1572 
1573   // Necessary to satisfy locking discipline assertions.
1574 
1575   MutexLocker x(Heap_lock);
1576 
1577   // While there are no constraints in the GC code that HeapWordSize
1578   // be any particular value, there are multiple other areas in the
1579   // system which believe this to be true (e.g. oop->object_size in some
1580   // cases incorrectly returns the size in wordSize units rather than
1581   // HeapWordSize).
1582   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1583 
1584   size_t init_byte_size = InitialHeapSize;
1585   size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1586 
1587   // Ensure that the sizes are properly aligned.
1588   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1589   Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1590   Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1591 
1592   // Reserve the maximum.
1593 
1594   // When compressed oops are enabled, the preferred heap base
1595   // is calculated by subtracting the requested size from the
1596   // 32Gb boundary and using the result as the base address for
1597   // heap reservation. If the requested size is not aligned to
1598   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1599   // into the ReservedHeapSpace constructor) then the actual
1600   // base of the reserved heap may end up differing from the
1601   // address that was requested (i.e. the preferred heap base).
1602   // If this happens then we could end up using a non-optimal
1603   // compressed oops mode.
1604 
1605   ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1606                                                      HeapAlignment);
1607 
1608   initialize_reserved_region(heap_rs);
1609 
1610   // Create the barrier set for the entire reserved region.
1611   G1CardTable* ct = new G1CardTable(heap_rs.region());
1612   ct->initialize();
1613   G1BarrierSet* bs = new G1BarrierSet(ct);
1614   bs->initialize();
1615   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1616   BarrierSet::set_barrier_set(bs);
1617   _card_table = ct;
1618 
1619   {
1620     G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1621     satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1622     satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1623   }
1624 
1625   // Create the hot card cache.
1626   _hot_card_cache = new G1HotCardCache(this);
1627 
1628   // Carve out the G1 part of the heap.
1629   ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1630   size_t page_size = actual_reserved_page_size(heap_rs);
1631   G1RegionToSpaceMapper* heap_storage =
1632     G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1633                                               g1_rs.size(),
1634                                               page_size,
1635                                               HeapRegion::GrainBytes,
1636                                               1,
1637                                               mtJavaHeap);
1638   if(heap_storage == NULL) {
1639     vm_shutdown_during_initialization("Could not initialize G1 heap");
1640     return JNI_ERR;
1641   }
1642 
1643   os::trace_page_sizes("Heap",
1644                        MinHeapSize,
1645                        reserved_byte_size,
1646                        page_size,
1647                        heap_rs.base(),
1648                        heap_rs.size());
1649   heap_storage->set_mapping_changed_listener(&_listener);
1650 
1651   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1652   G1RegionToSpaceMapper* bot_storage =
1653     create_aux_memory_mapper("Block Offset Table",
1654                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1655                              G1BlockOffsetTable::heap_map_factor());
1656 
1657   G1RegionToSpaceMapper* cardtable_storage =
1658     create_aux_memory_mapper("Card Table",
1659                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1660                              G1CardTable::heap_map_factor());
1661 
1662   G1RegionToSpaceMapper* card_counts_storage =
1663     create_aux_memory_mapper("Card Counts Table",
1664                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1665                              G1CardCounts::heap_map_factor());
1666 
1667   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1668   G1RegionToSpaceMapper* prev_bitmap_storage =
1669     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1670   G1RegionToSpaceMapper* next_bitmap_storage =
1671     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1672 
1673   _hrm = HeapRegionManager::create_manager(this);
1674 
1675   _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1676   _card_table->initialize(cardtable_storage);
1677 
1678   // Do later initialization work for concurrent refinement.
1679   _hot_card_cache->initialize(card_counts_storage);
1680 
1681   // 6843694 - ensure that the maximum region index can fit
1682   // in the remembered set structures.
1683   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1684   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1685 
1686   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1687   // start within the first card.
1688   guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1689   // Also create a G1 rem set.
1690   _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1691   _rem_set->initialize(max_reserved_capacity(), max_regions());
1692 
1693   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1694   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1695   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1696             "too many cards per region");
1697 
1698   FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1699 
1700   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1701 
1702   {
1703     HeapWord* start = _hrm->reserved().start();
1704     HeapWord* end = _hrm->reserved().end();
1705     size_t granularity = HeapRegion::GrainBytes;
1706 
1707     _region_attr.initialize(start, end, granularity);
1708     _humongous_reclaim_candidates.initialize(start, end, granularity);
1709   }
1710 
1711   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1712                           true /* are_GC_task_threads */,
1713                           false /* are_ConcurrentGC_threads */);
1714   if (_workers == NULL) {
1715     return JNI_ENOMEM;
1716   }
1717   _workers->initialize_workers();
1718 
1719   _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1720 
1721   // Create the G1ConcurrentMark data structure and thread.
1722   // (Must do this late, so that "max_regions" is defined.)
1723   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1724   _cm_thread = _cm->cm_thread();
1725 
1726   // Now expand into the initial heap size.
1727   if (!expand(init_byte_size, _workers)) {
1728     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1729     return JNI_ENOMEM;
1730   }
1731 
1732   // Perform any initialization actions delegated to the policy.
1733   policy()->init(this, &_collection_set);
1734 
1735   jint ecode = initialize_concurrent_refinement();
1736   if (ecode != JNI_OK) {
1737     return ecode;
1738   }
1739 
1740   ecode = initialize_young_gen_sampling_thread();
1741   if (ecode != JNI_OK) {
1742     return ecode;
1743   }
1744 
1745   {
1746     G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1747     dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1748     dcqs.set_max_cards(concurrent_refine()->red_zone());
1749   }
1750 
1751   // Here we allocate the dummy HeapRegion that is required by the
1752   // G1AllocRegion class.
1753   HeapRegion* dummy_region = _hrm->get_dummy_region();
1754 
1755   // We'll re-use the same region whether the alloc region will
1756   // require BOT updates or not and, if it doesn't, then a non-young
1757   // region will complain that it cannot support allocations without
1758   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1759   dummy_region->set_eden();
1760   // Make sure it's full.
1761   dummy_region->set_top(dummy_region->end());
1762   G1AllocRegion::setup(this, dummy_region);
1763 
1764   _allocator->init_mutator_alloc_regions();
1765 
1766   // Do create of the monitoring and management support so that
1767   // values in the heap have been properly initialized.
1768   _g1mm = new G1MonitoringSupport(this);
1769 
1770   G1StringDedup::initialize();
1771 
1772   _preserved_marks_set.init(ParallelGCThreads);
1773 
1774   _collection_set.initialize(max_regions());
1775 
1776   G1InitLogger::print();
1777 
1778   return JNI_OK;
1779 }
1780 
1781 void G1CollectedHeap::stop() {
1782   // Stop all concurrent threads. We do this to make sure these threads
1783   // do not continue to execute and access resources (e.g. logging)
1784   // that are destroyed during shutdown.
1785   _cr->stop();
1786   _young_gen_sampling_thread->stop();
1787   _cm_thread->stop();
1788   if (G1StringDedup::is_enabled()) {
1789     G1StringDedup::stop();
1790   }
1791 }
1792 
1793 void G1CollectedHeap::safepoint_synchronize_begin() {
1794   SuspendibleThreadSet::synchronize();
1795 }
1796 
1797 void G1CollectedHeap::safepoint_synchronize_end() {
1798   SuspendibleThreadSet::desynchronize();
1799 }
1800 
1801 void G1CollectedHeap::post_initialize() {
1802   CollectedHeap::post_initialize();
1803   ref_processing_init();
1804 }
1805 
1806 void G1CollectedHeap::ref_processing_init() {
1807   // Reference processing in G1 currently works as follows:
1808   //
1809   // * There are two reference processor instances. One is
1810   //   used to record and process discovered references
1811   //   during concurrent marking; the other is used to
1812   //   record and process references during STW pauses
1813   //   (both full and incremental).
1814   // * Both ref processors need to 'span' the entire heap as
1815   //   the regions in the collection set may be dotted around.
1816   //
1817   // * For the concurrent marking ref processor:
1818   //   * Reference discovery is enabled at concurrent start.
1819   //   * Reference discovery is disabled and the discovered
1820   //     references processed etc during remarking.
1821   //   * Reference discovery is MT (see below).
1822   //   * Reference discovery requires a barrier (see below).
1823   //   * Reference processing may or may not be MT
1824   //     (depending on the value of ParallelRefProcEnabled
1825   //     and ParallelGCThreads).
1826   //   * A full GC disables reference discovery by the CM
1827   //     ref processor and abandons any entries on it's
1828   //     discovered lists.
1829   //
1830   // * For the STW processor:
1831   //   * Non MT discovery is enabled at the start of a full GC.
1832   //   * Processing and enqueueing during a full GC is non-MT.
1833   //   * During a full GC, references are processed after marking.
1834   //
1835   //   * Discovery (may or may not be MT) is enabled at the start
1836   //     of an incremental evacuation pause.
1837   //   * References are processed near the end of a STW evacuation pause.
1838   //   * For both types of GC:
1839   //     * Discovery is atomic - i.e. not concurrent.
1840   //     * Reference discovery will not need a barrier.
1841 
1842   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1843 
1844   // Concurrent Mark ref processor
1845   _ref_processor_cm =
1846     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1847                            mt_processing,                                  // mt processing
1848                            ParallelGCThreads,                              // degree of mt processing
1849                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1850                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1851                            false,                                          // Reference discovery is not atomic
1852                            &_is_alive_closure_cm,                          // is alive closure
1853                            true);                                          // allow changes to number of processing threads
1854 
1855   // STW ref processor
1856   _ref_processor_stw =
1857     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1858                            mt_processing,                        // mt processing
1859                            ParallelGCThreads,                    // degree of mt processing
1860                            (ParallelGCThreads > 1),              // mt discovery
1861                            ParallelGCThreads,                    // degree of mt discovery
1862                            true,                                 // Reference discovery is atomic
1863                            &_is_alive_closure_stw,               // is alive closure
1864                            true);                                // allow changes to number of processing threads
1865 }
1866 
1867 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1868   return &_soft_ref_policy;
1869 }
1870 
1871 size_t G1CollectedHeap::capacity() const {
1872   return _hrm->length() * HeapRegion::GrainBytes;
1873 }
1874 
1875 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1876   return _hrm->total_free_bytes();
1877 }
1878 
1879 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1880   _hot_card_cache->drain(cl, worker_id);
1881 }
1882 
1883 // Computes the sum of the storage used by the various regions.
1884 size_t G1CollectedHeap::used() const {
1885   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1886   if (_archive_allocator != NULL) {
1887     result += _archive_allocator->used();
1888   }
1889   return result;
1890 }
1891 
1892 size_t G1CollectedHeap::used_unlocked() const {
1893   return _summary_bytes_used;
1894 }
1895 
1896 class SumUsedClosure: public HeapRegionClosure {
1897   size_t _used;
1898 public:
1899   SumUsedClosure() : _used(0) {}
1900   bool do_heap_region(HeapRegion* r) {
1901     _used += r->used();
1902     return false;
1903   }
1904   size_t result() { return _used; }
1905 };
1906 
1907 size_t G1CollectedHeap::recalculate_used() const {
1908   SumUsedClosure blk;
1909   heap_region_iterate(&blk);
1910   return blk.result();
1911 }
1912 
1913 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1914   switch (cause) {
1915     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1916     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1917     case GCCause::_wb_conc_mark:                        return true;
1918     default :                                           return false;
1919   }
1920 }
1921 
1922 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1923   switch (cause) {
1924     case GCCause::_g1_humongous_allocation: return true;
1925     case GCCause::_g1_periodic_collection:  return G1PeriodicGCInvokesConcurrent;
1926     case GCCause::_wb_breakpoint:           return true;
1927     default:                                return is_user_requested_concurrent_full_gc(cause);
1928   }
1929 }
1930 
1931 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
1932   if (policy()->force_upgrade_to_full()) {
1933     return true;
1934   } else if (should_do_concurrent_full_gc(_gc_cause)) {
1935     return false;
1936   } else if (has_regions_left_for_allocation()) {
1937     return false;
1938   } else {
1939     return true;
1940   }
1941 }
1942 
1943 #ifndef PRODUCT
1944 void G1CollectedHeap::allocate_dummy_regions() {
1945   // Let's fill up most of the region
1946   size_t word_size = HeapRegion::GrainWords - 1024;
1947   // And as a result the region we'll allocate will be humongous.
1948   guarantee(is_humongous(word_size), "sanity");
1949 
1950   // _filler_array_max_size is set to humongous object threshold
1951   // but temporarily change it to use CollectedHeap::fill_with_object().
1952   AutoModifyRestore<size_t> temporarily(_filler_array_max_size, word_size);
1953 
1954   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1955     // Let's use the existing mechanism for the allocation
1956     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1957     if (dummy_obj != NULL) {
1958       MemRegion mr(dummy_obj, word_size);
1959       CollectedHeap::fill_with_object(mr);
1960     } else {
1961       // If we can't allocate once, we probably cannot allocate
1962       // again. Let's get out of the loop.
1963       break;
1964     }
1965   }
1966 }
1967 #endif // !PRODUCT
1968 
1969 void G1CollectedHeap::increment_old_marking_cycles_started() {
1970   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1971          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1972          "Wrong marking cycle count (started: %d, completed: %d)",
1973          _old_marking_cycles_started, _old_marking_cycles_completed);
1974 
1975   _old_marking_cycles_started++;
1976 }
1977 
1978 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1979                                                              bool whole_heap_examined) {
1980   MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1981 
1982   // We assume that if concurrent == true, then the caller is a
1983   // concurrent thread that was joined the Suspendible Thread
1984   // Set. If there's ever a cheap way to check this, we should add an
1985   // assert here.
1986 
1987   // Given that this method is called at the end of a Full GC or of a
1988   // concurrent cycle, and those can be nested (i.e., a Full GC can
1989   // interrupt a concurrent cycle), the number of full collections
1990   // completed should be either one (in the case where there was no
1991   // nesting) or two (when a Full GC interrupted a concurrent cycle)
1992   // behind the number of full collections started.
1993 
1994   // This is the case for the inner caller, i.e. a Full GC.
1995   assert(concurrent ||
1996          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1997          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1998          "for inner caller (Full GC): _old_marking_cycles_started = %u "
1999          "is inconsistent with _old_marking_cycles_completed = %u",
2000          _old_marking_cycles_started, _old_marking_cycles_completed);
2001 
2002   // This is the case for the outer caller, i.e. the concurrent cycle.
2003   assert(!concurrent ||
2004          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2005          "for outer caller (concurrent cycle): "
2006          "_old_marking_cycles_started = %u "
2007          "is inconsistent with _old_marking_cycles_completed = %u",
2008          _old_marking_cycles_started, _old_marking_cycles_completed);
2009 
2010   _old_marking_cycles_completed += 1;
2011   if (whole_heap_examined) {
2012     // Signal that we have completed a visit to all live objects.
2013     record_whole_heap_examined_timestamp();
2014   }
2015 
2016   // We need to clear the "in_progress" flag in the CM thread before
2017   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2018   // is set) so that if a waiter requests another System.gc() it doesn't
2019   // incorrectly see that a marking cycle is still in progress.
2020   if (concurrent) {
2021     _cm_thread->set_idle();
2022   }
2023 
2024   // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2025   // for a full GC to finish that their wait is over.
2026   ml.notify_all();
2027 }
2028 
2029 void G1CollectedHeap::collect(GCCause::Cause cause) {
2030   try_collect(cause);
2031 }
2032 
2033 // Return true if (x < y) with allowance for wraparound.
2034 static bool gc_counter_less_than(uint x, uint y) {
2035   return (x - y) > (UINT_MAX/2);
2036 }
2037 
2038 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2039 // Macro so msg printing is format-checked.
2040 #define LOG_COLLECT_CONCURRENTLY(cause, ...)                            \
2041   do {                                                                  \
2042     LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt;                   \
2043     if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) {                     \
2044       ResourceMark rm; /* For thread name. */                           \
2045       LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2046       LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2047                                        Thread::current()->name(),       \
2048                                        GCCause::to_string(cause));      \
2049       LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__);                    \
2050     }                                                                   \
2051   } while (0)
2052 
2053 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2054   LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2055 
2056 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2057                                                uint gc_counter,
2058                                                uint old_marking_started_before) {
2059   assert_heap_not_locked();
2060   assert(should_do_concurrent_full_gc(cause),
2061          "Non-concurrent cause %s", GCCause::to_string(cause));
2062 
2063   for (uint i = 1; true; ++i) {
2064     // Try to schedule concurrent start evacuation pause that will
2065     // start a concurrent cycle.
2066     LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2067     VM_G1TryInitiateConcMark op(gc_counter,
2068                                 cause,
2069                                 policy()->max_pause_time_ms());
2070     VMThread::execute(&op);
2071 
2072     // Request is trivially finished.
2073     if (cause == GCCause::_g1_periodic_collection) {
2074       LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2075       return op.gc_succeeded();
2076     }
2077 
2078     // If VMOp skipped initiating concurrent marking cycle because
2079     // we're terminating, then we're done.
2080     if (op.terminating()) {
2081       LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2082       return false;
2083     }
2084 
2085     // Lock to get consistent set of values.
2086     uint old_marking_started_after;
2087     uint old_marking_completed_after;
2088     {
2089       MutexLocker ml(Heap_lock);
2090       // Update gc_counter for retrying VMOp if needed. Captured here to be
2091       // consistent with the values we use below for termination tests.  If
2092       // a retry is needed after a possible wait, and another collection
2093       // occurs in the meantime, it will cause our retry to be skipped and
2094       // we'll recheck for termination with updated conditions from that
2095       // more recent collection.  That's what we want, rather than having
2096       // our retry possibly perform an unnecessary collection.
2097       gc_counter = total_collections();
2098       old_marking_started_after = _old_marking_cycles_started;
2099       old_marking_completed_after = _old_marking_cycles_completed;
2100     }
2101 
2102     if (cause == GCCause::_wb_breakpoint) {
2103       if (op.gc_succeeded()) {
2104         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2105         return true;
2106       }
2107       // When _wb_breakpoint there can't be another cycle or deferred.
2108       assert(!op.cycle_already_in_progress(), "invariant");
2109       assert(!op.whitebox_attached(), "invariant");
2110       // Concurrent cycle attempt might have been cancelled by some other
2111       // collection, so retry.  Unlike other cases below, we want to retry
2112       // even if cancelled by a STW full collection, because we really want
2113       // to start a concurrent cycle.
2114       if (old_marking_started_before != old_marking_started_after) {
2115         LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2116         old_marking_started_before = old_marking_started_after;
2117       }
2118     } else if (!GCCause::is_user_requested_gc(cause)) {
2119       // For an "automatic" (not user-requested) collection, we just need to
2120       // ensure that progress is made.
2121       //
2122       // Request is finished if any of
2123       // (1) the VMOp successfully performed a GC,
2124       // (2) a concurrent cycle was already in progress,
2125       // (3) whitebox is controlling concurrent cycles,
2126       // (4) a new cycle was started (by this thread or some other), or
2127       // (5) a Full GC was performed.
2128       // Cases (4) and (5) are detected together by a change to
2129       // _old_marking_cycles_started.
2130       //
2131       // Note that (1) does not imply (4).  If we're still in the mixed
2132       // phase of an earlier concurrent collection, the request to make the
2133       // collection a concurrent start won't be honored.  If we don't check for
2134       // both conditions we'll spin doing back-to-back collections.
2135       if (op.gc_succeeded() ||
2136           op.cycle_already_in_progress() ||
2137           op.whitebox_attached() ||
2138           (old_marking_started_before != old_marking_started_after)) {
2139         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2140         return true;
2141       }
2142     } else {                    // User-requested GC.
2143       // For a user-requested collection, we want to ensure that a complete
2144       // full collection has been performed before returning, but without
2145       // waiting for more than needed.
2146 
2147       // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2148       // new cycle was started.  That's good, because it's not clear what we
2149       // should do otherwise.  Trying again just does back to back GCs.
2150       // Can't wait for someone else to start a cycle.  And returning fails
2151       // to meet the goal of ensuring a full collection was performed.
2152       assert(!op.gc_succeeded() ||
2153              (old_marking_started_before != old_marking_started_after),
2154              "invariant: succeeded %s, started before %u, started after %u",
2155              BOOL_TO_STR(op.gc_succeeded()),
2156              old_marking_started_before, old_marking_started_after);
2157 
2158       // Request is finished if a full collection (concurrent or stw)
2159       // was started after this request and has completed, e.g.
2160       // started_before < completed_after.
2161       if (gc_counter_less_than(old_marking_started_before,
2162                                old_marking_completed_after)) {
2163         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2164         return true;
2165       }
2166 
2167       if (old_marking_started_after != old_marking_completed_after) {
2168         // If there is an in-progress cycle (possibly started by us), then
2169         // wait for that cycle to complete, e.g.
2170         // while completed_now < started_after.
2171         LOG_COLLECT_CONCURRENTLY(cause, "wait");
2172         MonitorLocker ml(G1OldGCCount_lock);
2173         while (gc_counter_less_than(_old_marking_cycles_completed,
2174                                     old_marking_started_after)) {
2175           ml.wait();
2176         }
2177         // Request is finished if the collection we just waited for was
2178         // started after this request.
2179         if (old_marking_started_before != old_marking_started_after) {
2180           LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2181           return true;
2182         }
2183       }
2184 
2185       // If VMOp was successful then it started a new cycle that the above
2186       // wait &etc should have recognized as finishing this request.  This
2187       // differs from a non-user-request, where gc_succeeded does not imply
2188       // a new cycle was started.
2189       assert(!op.gc_succeeded(), "invariant");
2190 
2191       if (op.cycle_already_in_progress()) {
2192         // If VMOp failed because a cycle was already in progress, it
2193         // is now complete.  But it didn't finish this user-requested
2194         // GC, so try again.
2195         LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2196         continue;
2197       } else if (op.whitebox_attached()) {
2198         // If WhiteBox wants control, wait for notification of a state
2199         // change in the controller, then try again.  Don't wait for
2200         // release of control, since collections may complete while in
2201         // control.  Note: This won't recognize a STW full collection
2202         // while waiting; we can't wait on multiple monitors.
2203         LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2204         MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2205         if (ConcurrentGCBreakpoints::is_controlled()) {
2206           ml.wait();
2207         }
2208         continue;
2209       }
2210     }
2211 
2212     // Collection failed and should be retried.
2213     assert(op.transient_failure(), "invariant");
2214 
2215     if (GCLocker::is_active_and_needs_gc()) {
2216       // If GCLocker is active, wait until clear before retrying.
2217       LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2218       GCLocker::stall_until_clear();
2219     }
2220 
2221     LOG_COLLECT_CONCURRENTLY(cause, "retry");
2222   }
2223 }
2224 
2225 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2226   assert_heap_not_locked();
2227 
2228   // Lock to get consistent set of values.
2229   uint gc_count_before;
2230   uint full_gc_count_before;
2231   uint old_marking_started_before;
2232   {
2233     MutexLocker ml(Heap_lock);
2234     gc_count_before = total_collections();
2235     full_gc_count_before = total_full_collections();
2236     old_marking_started_before = _old_marking_cycles_started;
2237   }
2238 
2239   if (should_do_concurrent_full_gc(cause)) {
2240     return try_collect_concurrently(cause,
2241                                     gc_count_before,
2242                                     old_marking_started_before);
2243   } else if (GCLocker::should_discard(cause, gc_count_before)) {
2244     // Indicate failure to be consistent with VMOp failure due to
2245     // another collection slipping in after our gc_count but before
2246     // our request is processed.
2247     return false;
2248   } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2249              DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2250 
2251     // Schedule a standard evacuation pause. We're setting word_size
2252     // to 0 which means that we are not requesting a post-GC allocation.
2253     VM_G1CollectForAllocation op(0,     /* word_size */
2254                                  gc_count_before,
2255                                  cause,
2256                                  policy()->max_pause_time_ms());
2257     VMThread::execute(&op);
2258     return op.gc_succeeded();
2259   } else {
2260     // Schedule a Full GC.
2261     VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2262     VMThread::execute(&op);
2263     return op.gc_succeeded();
2264   }
2265 }
2266 
2267 bool G1CollectedHeap::is_in(const void* p) const {
2268   if (_hrm->reserved().contains(p)) {
2269     // Given that we know that p is in the reserved space,
2270     // heap_region_containing() should successfully
2271     // return the containing region.
2272     HeapRegion* hr = heap_region_containing(p);
2273     return hr->is_in(p);
2274   } else {
2275     return false;
2276   }
2277 }
2278 
2279 #ifdef ASSERT
2280 bool G1CollectedHeap::is_in_exact(const void* p) const {
2281   bool contains = reserved_region().contains(p);
2282   bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2283   if (contains && available) {
2284     return true;
2285   } else {
2286     return false;
2287   }
2288 }
2289 #endif
2290 
2291 // Iteration functions.
2292 
2293 // Iterates an ObjectClosure over all objects within a HeapRegion.
2294 
2295 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2296   ObjectClosure* _cl;
2297 public:
2298   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2299   bool do_heap_region(HeapRegion* r) {
2300     if (!r->is_continues_humongous()) {
2301       r->object_iterate(_cl);
2302     }
2303     return false;
2304   }
2305 };
2306 
2307 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2308   IterateObjectClosureRegionClosure blk(cl);
2309   heap_region_iterate(&blk);
2310 }
2311 
2312 class G1ParallelObjectIterator : public ParallelObjectIterator {
2313 private:
2314   G1CollectedHeap*  _heap;
2315   HeapRegionClaimer _claimer;
2316 
2317 public:
2318   G1ParallelObjectIterator(uint thread_num) :
2319       _heap(G1CollectedHeap::heap()),
2320       _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2321 
2322   virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2323     _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2324   }
2325 };
2326 
2327 ParallelObjectIterator* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2328   return new G1ParallelObjectIterator(thread_num);
2329 }
2330 
2331 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2332   IterateObjectClosureRegionClosure blk(cl);
2333   heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2334 }
2335 
2336 void G1CollectedHeap::keep_alive(oop obj) {
2337   G1BarrierSet::enqueue(obj);
2338 }
2339 
2340 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2341   _hrm->iterate(cl);
2342 }
2343 
2344 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2345                                                                  HeapRegionClaimer *hrclaimer,
2346                                                                  uint worker_id) const {
2347   _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2348 }
2349 
2350 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2351                                                          HeapRegionClaimer *hrclaimer) const {
2352   _hrm->par_iterate(cl, hrclaimer, 0);
2353 }
2354 
2355 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2356   _collection_set.iterate(cl);
2357 }
2358 
2359 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2360   _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2361 }
2362 
2363 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2364   _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2365 }
2366 
2367 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2368   HeapRegion* hr = heap_region_containing(addr);
2369   return hr->block_start(addr);
2370 }
2371 
2372 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2373   HeapRegion* hr = heap_region_containing(addr);
2374   return hr->block_is_obj(addr);
2375 }
2376 
2377 bool G1CollectedHeap::supports_tlab_allocation() const {
2378   return true;
2379 }
2380 
2381 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2382   return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2383 }
2384 
2385 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2386   return _eden.length() * HeapRegion::GrainBytes;
2387 }
2388 
2389 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2390 // must be equal to the humongous object limit.
2391 size_t G1CollectedHeap::max_tlab_size() const {
2392   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2393 }
2394 
2395 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2396   return _allocator->unsafe_max_tlab_alloc();
2397 }
2398 
2399 size_t G1CollectedHeap::max_capacity() const {
2400   return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2401 }
2402 
2403 size_t G1CollectedHeap::max_reserved_capacity() const {
2404   return _hrm->max_length() * HeapRegion::GrainBytes;
2405 }
2406 
2407 void G1CollectedHeap::deduplicate_string(oop str) {
2408   assert(java_lang_String::is_instance(str), "invariant");
2409 
2410   if (G1StringDedup::is_enabled()) {
2411     G1StringDedup::deduplicate(str);
2412   }
2413 }
2414 
2415 void G1CollectedHeap::prepare_for_verify() {
2416   _verifier->prepare_for_verify();
2417 }
2418 
2419 void G1CollectedHeap::verify(VerifyOption vo) {
2420   _verifier->verify(vo);
2421 }
2422 
2423 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2424   return true;
2425 }
2426 
2427 bool G1CollectedHeap::is_heterogeneous_heap() const {
2428   return G1Arguments::is_heterogeneous_heap();
2429 }
2430 
2431 class PrintRegionClosure: public HeapRegionClosure {
2432   outputStream* _st;
2433 public:
2434   PrintRegionClosure(outputStream* st) : _st(st) {}
2435   bool do_heap_region(HeapRegion* r) {
2436     r->print_on(_st);
2437     return false;
2438   }
2439 };
2440 
2441 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2442                                        const HeapRegion* hr,
2443                                        const VerifyOption vo) const {
2444   switch (vo) {
2445   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2446   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2447   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2448   default:                            ShouldNotReachHere();
2449   }
2450   return false; // keep some compilers happy
2451 }
2452 
2453 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2454                                        const VerifyOption vo) const {
2455   switch (vo) {
2456   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2457   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2458   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2459   default:                            ShouldNotReachHere();
2460   }
2461   return false; // keep some compilers happy
2462 }
2463 
2464 void G1CollectedHeap::print_heap_regions() const {
2465   LogTarget(Trace, gc, heap, region) lt;
2466   if (lt.is_enabled()) {
2467     LogStream ls(lt);
2468     print_regions_on(&ls);
2469   }
2470 }
2471 
2472 void G1CollectedHeap::print_on(outputStream* st) const {
2473   st->print(" %-20s", "garbage-first heap");
2474   if (_hrm != NULL) {
2475     st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2476               capacity()/K, used_unlocked()/K);
2477     st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2478               p2i(_hrm->reserved().start()),
2479               p2i(_hrm->reserved().end()));
2480   }
2481   st->cr();
2482   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2483   uint young_regions = young_regions_count();
2484   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2485             (size_t) young_regions * HeapRegion::GrainBytes / K);
2486   uint survivor_regions = survivor_regions_count();
2487   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2488             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2489   st->cr();
2490   if (_numa->is_enabled()) {
2491     uint num_nodes = _numa->num_active_nodes();
2492     st->print("  remaining free region(s) on each NUMA node: ");
2493     const int* node_ids = _numa->node_ids();
2494     for (uint node_index = 0; node_index < num_nodes; node_index++) {
2495       uint num_free_regions = (_hrm != NULL ? _hrm->num_free_regions(node_index) : 0);
2496       st->print("%d=%u ", node_ids[node_index], num_free_regions);
2497     }
2498     st->cr();
2499   }
2500   MetaspaceUtils::print_on(st);
2501 }
2502 
2503 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2504   if (_hrm == NULL) {
2505     return;
2506   }
2507 
2508   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2509                "HS=humongous(starts), HC=humongous(continues), "
2510                "CS=collection set, F=free, "
2511                "OA=open archive, CA=closed archive, "
2512                "TAMS=top-at-mark-start (previous, next)");
2513   PrintRegionClosure blk(st);
2514   heap_region_iterate(&blk);
2515 }
2516 
2517 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2518   print_on(st);
2519 
2520   // Print the per-region information.
2521   if (_hrm != NULL) {
2522     st->cr();
2523     print_regions_on(st);
2524   }
2525 }
2526 
2527 void G1CollectedHeap::print_on_error(outputStream* st) const {
2528   this->CollectedHeap::print_on_error(st);
2529 
2530   if (_cm != NULL) {
2531     st->cr();
2532     _cm->print_on_error(st);
2533   }
2534 }
2535 
2536 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2537   workers()->threads_do(tc);
2538   tc->do_thread(_cm_thread);
2539   _cm->threads_do(tc);
2540   _cr->threads_do(tc);
2541   tc->do_thread(_young_gen_sampling_thread);
2542   if (G1StringDedup::is_enabled()) {
2543     G1StringDedup::threads_do(tc);
2544   }
2545 }
2546 
2547 void G1CollectedHeap::print_tracing_info() const {
2548   rem_set()->print_summary_info();
2549   concurrent_mark()->print_summary_info();
2550 }
2551 
2552 #ifndef PRODUCT
2553 // Helpful for debugging RSet issues.
2554 
2555 class PrintRSetsClosure : public HeapRegionClosure {
2556 private:
2557   const char* _msg;
2558   size_t _occupied_sum;
2559 
2560 public:
2561   bool do_heap_region(HeapRegion* r) {
2562     HeapRegionRemSet* hrrs = r->rem_set();
2563     size_t occupied = hrrs->occupied();
2564     _occupied_sum += occupied;
2565 
2566     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2567     if (occupied == 0) {
2568       tty->print_cr("  RSet is empty");
2569     } else {
2570       hrrs->print();
2571     }
2572     tty->print_cr("----------");
2573     return false;
2574   }
2575 
2576   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2577     tty->cr();
2578     tty->print_cr("========================================");
2579     tty->print_cr("%s", msg);
2580     tty->cr();
2581   }
2582 
2583   ~PrintRSetsClosure() {
2584     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2585     tty->print_cr("========================================");
2586     tty->cr();
2587   }
2588 };
2589 
2590 void G1CollectedHeap::print_cset_rsets() {
2591   PrintRSetsClosure cl("Printing CSet RSets");
2592   collection_set_iterate_all(&cl);
2593 }
2594 
2595 void G1CollectedHeap::print_all_rsets() {
2596   PrintRSetsClosure cl("Printing All RSets");;
2597   heap_region_iterate(&cl);
2598 }
2599 #endif // PRODUCT
2600 
2601 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2602   return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2603 }
2604 
2605 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2606 
2607   size_t eden_used_bytes = _eden.used_bytes();
2608   size_t survivor_used_bytes = _survivor.used_bytes();
2609   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2610 
2611   size_t eden_capacity_bytes =
2612     (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2613 
2614   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2615   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2616                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2617 }
2618 
2619 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2620   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2621                        stats->unused(), stats->used(), stats->region_end_waste(),
2622                        stats->regions_filled(), stats->direct_allocated(),
2623                        stats->failure_used(), stats->failure_waste());
2624 }
2625 
2626 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2627   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2628   gc_tracer->report_gc_heap_summary(when, heap_summary);
2629 
2630   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2631   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2632 }
2633 
2634 void G1CollectedHeap::gc_prologue(bool full) {
2635   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2636 
2637   // This summary needs to be printed before incrementing total collections.
2638   rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2639 
2640   // Update common counters.
2641   increment_total_collections(full /* full gc */);
2642   if (full || collector_state()->in_concurrent_start_gc()) {
2643     increment_old_marking_cycles_started();
2644   }
2645 
2646   // Fill TLAB's and such
2647   {
2648     Ticks start = Ticks::now();
2649     ensure_parsability(true);
2650     Tickspan dt = Ticks::now() - start;
2651     phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS);
2652   }
2653 
2654   if (!full) {
2655     // Flush dirty card queues to qset, so later phases don't need to account
2656     // for partially filled per-thread queues and such.  Not needed for full
2657     // collections, which ignore those logs.
2658     Ticks start = Ticks::now();
2659     G1BarrierSet::dirty_card_queue_set().concatenate_logs();
2660     Tickspan dt = Ticks::now() - start;
2661     phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS);
2662   }
2663 }
2664 
2665 void G1CollectedHeap::gc_epilogue(bool full) {
2666   // Update common counters.
2667   if (full) {
2668     // Update the number of full collections that have been completed.
2669     increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2670   }
2671 
2672   // We are at the end of the GC. Total collections has already been increased.
2673   rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2674 
2675   // FIXME: what is this about?
2676   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2677   // is set.
2678 #if COMPILER2_OR_JVMCI
2679   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2680 #endif
2681 
2682   double start = os::elapsedTime();
2683   resize_all_tlabs();
2684   phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2685 
2686   MemoryService::track_memory_usage();
2687   // We have just completed a GC. Update the soft reference
2688   // policy with the new heap occupancy
2689   Universe::update_heap_info_at_gc();
2690 
2691   // Print NUMA statistics.
2692   _numa->print_statistics();
2693 
2694   _collection_pause_end = Ticks::now();
2695 }
2696 
2697 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2698   LogTarget(Trace, gc, heap, verify) lt;
2699 
2700   if (lt.is_enabled()) {
2701     LogStream ls(lt);
2702     // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2703     G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2704     heap_region_iterate(&cl);
2705   }
2706 }
2707 
2708 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2709                                                uint gc_count_before,
2710                                                bool* succeeded,
2711                                                GCCause::Cause gc_cause) {
2712   assert_heap_not_locked_and_not_at_safepoint();
2713   VM_G1CollectForAllocation op(word_size,
2714                                gc_count_before,
2715                                gc_cause,
2716                                policy()->max_pause_time_ms());
2717   VMThread::execute(&op);
2718 
2719   HeapWord* result = op.result();
2720   bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2721   assert(result == NULL || ret_succeeded,
2722          "the result should be NULL if the VM did not succeed");
2723   *succeeded = ret_succeeded;
2724 
2725   assert_heap_not_locked();
2726   return result;
2727 }
2728 
2729 void G1CollectedHeap::do_concurrent_mark() {
2730   MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2731   if (!_cm_thread->in_progress()) {
2732     _cm_thread->set_started();
2733     CGC_lock->notify();
2734   }
2735 }
2736 
2737 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2738   // We don't nominate objects with many remembered set entries, on
2739   // the assumption that such objects are likely still live.
2740   HeapRegionRemSet* rem_set = r->rem_set();
2741 
2742   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2743          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2744          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2745 }
2746 
2747 #ifndef PRODUCT
2748 void G1CollectedHeap::verify_region_attr_remset_update() {
2749   class VerifyRegionAttrRemSet : public HeapRegionClosure {
2750   public:
2751     virtual bool do_heap_region(HeapRegion* r) {
2752       G1CollectedHeap* g1h = G1CollectedHeap::heap();
2753       bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2754       assert(r->rem_set()->is_tracked() == needs_remset_update,
2755              "Region %u remset tracking status (%s) different to region attribute (%s)",
2756              r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2757       return false;
2758     }
2759   } cl;
2760   heap_region_iterate(&cl);
2761 }
2762 #endif
2763 
2764 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2765   public:
2766     bool do_heap_region(HeapRegion* hr) {
2767       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2768         hr->verify_rem_set();
2769       }
2770       return false;
2771     }
2772 };
2773 
2774 uint G1CollectedHeap::num_task_queues() const {
2775   return _task_queues->size();
2776 }
2777 
2778 #if TASKQUEUE_STATS
2779 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2780   st->print_raw_cr("GC Task Stats");
2781   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2782   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2783 }
2784 
2785 void G1CollectedHeap::print_taskqueue_stats() const {
2786   if (!log_is_enabled(Trace, gc, task, stats)) {
2787     return;
2788   }
2789   Log(gc, task, stats) log;
2790   ResourceMark rm;
2791   LogStream ls(log.trace());
2792   outputStream* st = &ls;
2793 
2794   print_taskqueue_stats_hdr(st);
2795 
2796   TaskQueueStats totals;
2797   const uint n = num_task_queues();
2798   for (uint i = 0; i < n; ++i) {
2799     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2800     totals += task_queue(i)->stats;
2801   }
2802   st->print_raw("tot "); totals.print(st); st->cr();
2803 
2804   DEBUG_ONLY(totals.verify());
2805 }
2806 
2807 void G1CollectedHeap::reset_taskqueue_stats() {
2808   const uint n = num_task_queues();
2809   for (uint i = 0; i < n; ++i) {
2810     task_queue(i)->stats.reset();
2811   }
2812 }
2813 #endif // TASKQUEUE_STATS
2814 
2815 void G1CollectedHeap::wait_for_root_region_scanning() {
2816   double scan_wait_start = os::elapsedTime();
2817   // We have to wait until the CM threads finish scanning the
2818   // root regions as it's the only way to ensure that all the
2819   // objects on them have been correctly scanned before we start
2820   // moving them during the GC.
2821   bool waited = _cm->root_regions()->wait_until_scan_finished();
2822   double wait_time_ms = 0.0;
2823   if (waited) {
2824     double scan_wait_end = os::elapsedTime();
2825     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2826   }
2827   phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2828 }
2829 
2830 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2831 private:
2832   G1HRPrinter* _hr_printer;
2833 public:
2834   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2835 
2836   virtual bool do_heap_region(HeapRegion* r) {
2837     _hr_printer->cset(r);
2838     return false;
2839   }
2840 };
2841 
2842 void G1CollectedHeap::start_new_collection_set() {
2843   double start = os::elapsedTime();
2844 
2845   collection_set()->start_incremental_building();
2846 
2847   clear_region_attr();
2848 
2849   guarantee(_eden.length() == 0, "eden should have been cleared");
2850   policy()->transfer_survivors_to_cset(survivor());
2851 
2852   // We redo the verification but now wrt to the new CSet which
2853   // has just got initialized after the previous CSet was freed.
2854   _cm->verify_no_collection_set_oops();
2855 
2856   phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2857 }
2858 
2859 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2860 
2861   _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2862   evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2863                                             collection_set()->optional_region_length());
2864 
2865   _cm->verify_no_collection_set_oops();
2866 
2867   if (_hr_printer.is_active()) {
2868     G1PrintCollectionSetClosure cl(&_hr_printer);
2869     _collection_set.iterate(&cl);
2870     _collection_set.iterate_optional(&cl);
2871   }
2872 }
2873 
2874 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2875   if (collector_state()->in_concurrent_start_gc()) {
2876     return G1HeapVerifier::G1VerifyConcurrentStart;
2877   } else if (collector_state()->in_young_only_phase()) {
2878     return G1HeapVerifier::G1VerifyYoungNormal;
2879   } else {
2880     return G1HeapVerifier::G1VerifyMixed;
2881   }
2882 }
2883 
2884 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2885   if (VerifyRememberedSets) {
2886     log_info(gc, verify)("[Verifying RemSets before GC]");
2887     VerifyRegionRemSetClosure v_cl;
2888     heap_region_iterate(&v_cl);
2889   }
2890   _verifier->verify_before_gc(type);
2891   _verifier->check_bitmaps("GC Start");
2892   verify_numa_regions("GC Start");
2893 }
2894 
2895 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2896   if (VerifyRememberedSets) {
2897     log_info(gc, verify)("[Verifying RemSets after GC]");
2898     VerifyRegionRemSetClosure v_cl;
2899     heap_region_iterate(&v_cl);
2900   }
2901   _verifier->verify_after_gc(type);
2902   _verifier->check_bitmaps("GC End");
2903   verify_numa_regions("GC End");
2904 }
2905 
2906 void G1CollectedHeap::expand_heap_after_young_collection(){
2907   size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2908   if (expand_bytes > 0) {
2909     // No need for an ergo logging here,
2910     // expansion_amount() does this when it returns a value > 0.
2911     double expand_ms;
2912     if (!expand(expand_bytes, _workers, &expand_ms)) {
2913       // We failed to expand the heap. Cannot do anything about it.
2914     }
2915     phase_times()->record_expand_heap_time(expand_ms);
2916   }
2917 }
2918 
2919 const char* G1CollectedHeap::young_gc_name() const {
2920   if (collector_state()->in_concurrent_start_gc()) {
2921     return "Pause Young (Concurrent Start)";
2922   } else if (collector_state()->in_young_only_phase()) {
2923     if (collector_state()->in_young_gc_before_mixed()) {
2924       return "Pause Young (Prepare Mixed)";
2925     } else {
2926       return "Pause Young (Normal)";
2927     }
2928   } else {
2929     return "Pause Young (Mixed)";
2930   }
2931 }
2932 
2933 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2934   assert_at_safepoint_on_vm_thread();
2935   guarantee(!is_gc_active(), "collection is not reentrant");
2936 
2937   if (GCLocker::check_active_before_gc()) {
2938     return false;
2939   }
2940 
2941   do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2942   if (should_upgrade_to_full_gc(gc_cause())) {
2943     log_info(gc, ergo)("Attempting maximally compacting collection");
2944     bool result = do_full_collection(false /* explicit gc */,
2945                                      true /* clear_all_soft_refs */);
2946     // do_full_collection only fails if blocked by GC locker, but
2947     // we've already checked for that above.
2948     assert(result, "invariant");
2949   }
2950   return true;
2951 }
2952 
2953 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2954   GCIdMark gc_id_mark;
2955 
2956   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2957   ResourceMark rm;
2958 
2959   policy()->note_gc_start();
2960 
2961   _gc_timer_stw->register_gc_start();
2962   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2963 
2964   wait_for_root_region_scanning();
2965 
2966   print_heap_before_gc();
2967   print_heap_regions();
2968   trace_heap_before_gc(_gc_tracer_stw);
2969 
2970   _verifier->verify_region_sets_optional();
2971   _verifier->verify_dirty_young_regions();
2972 
2973   // We should not be doing concurrent start unless the concurrent mark thread is running
2974   if (!_cm_thread->should_terminate()) {
2975     // This call will decide whether this pause is a concurrent start
2976     // pause. If it is, in_concurrent_start_gc() will return true
2977     // for the duration of this pause.
2978     policy()->decide_on_conc_mark_initiation();
2979   }
2980 
2981   // We do not allow concurrent start to be piggy-backed on a mixed GC.
2982   assert(!collector_state()->in_concurrent_start_gc() ||
2983          collector_state()->in_young_only_phase(), "sanity");
2984   // We also do not allow mixed GCs during marking.
2985   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2986 
2987   // Record whether this pause is a concurrent start. When the current
2988   // thread has completed its logging output and it's safe to signal
2989   // the CM thread, the flag's value in the policy has been reset.
2990   bool should_start_conc_mark = collector_state()->in_concurrent_start_gc();
2991   if (should_start_conc_mark) {
2992     _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2993   }
2994 
2995   // Inner scope for scope based logging, timers, and stats collection
2996   {
2997     G1EvacuationInfo evacuation_info;
2998 
2999     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3000 
3001     GCTraceCPUTime tcpu;
3002 
3003     GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3004 
3005     uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3006                                                             workers()->active_workers(),
3007                                                             Threads::number_of_non_daemon_threads());
3008     active_workers = workers()->update_active_workers(active_workers);
3009     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3010 
3011     G1MonitoringScope ms(g1mm(),
3012                          false /* full_gc */,
3013                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3014 
3015     G1HeapTransition heap_transition(this);
3016 
3017     {
3018       IsGCActiveMark x;
3019 
3020       gc_prologue(false);
3021 
3022       G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3023       verify_before_young_collection(verify_type);
3024 
3025       {
3026         // The elapsed time induced by the start time below deliberately elides
3027         // the possible verification above.
3028         double sample_start_time_sec = os::elapsedTime();
3029 
3030         // Please see comment in g1CollectedHeap.hpp and
3031         // G1CollectedHeap::ref_processing_init() to see how
3032         // reference processing currently works in G1.
3033         _ref_processor_stw->enable_discovery();
3034 
3035         // We want to temporarily turn off discovery by the
3036         // CM ref processor, if necessary, and turn it back on
3037         // on again later if we do. Using a scoped
3038         // NoRefDiscovery object will do this.
3039         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3040 
3041         policy()->record_collection_pause_start(sample_start_time_sec);
3042 
3043         // Forget the current allocation region (we might even choose it to be part
3044         // of the collection set!).
3045         _allocator->release_mutator_alloc_regions();
3046 
3047         calculate_collection_set(evacuation_info, target_pause_time_ms);
3048 
3049         G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3050         G1ParScanThreadStateSet per_thread_states(this,
3051                                                   &rdcqs,
3052                                                   workers()->active_workers(),
3053                                                   collection_set()->young_region_length(),
3054                                                   collection_set()->optional_region_length());
3055         pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3056 
3057         // Actually do the work...
3058         evacuate_initial_collection_set(&per_thread_states);
3059 
3060         if (_collection_set.optional_region_length() != 0) {
3061           evacuate_optional_collection_set(&per_thread_states);
3062         }
3063         post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3064 
3065         start_new_collection_set();
3066 
3067         _survivor_evac_stats.adjust_desired_plab_sz();
3068         _old_evac_stats.adjust_desired_plab_sz();
3069 
3070         if (should_start_conc_mark) {
3071           // We have to do this before we notify the CM threads that
3072           // they can start working to make sure that all the
3073           // appropriate initialization is done on the CM object.
3074           concurrent_mark()->post_concurrent_start();
3075           // Note that we don't actually trigger the CM thread at
3076           // this point. We do that later when we're sure that
3077           // the current thread has completed its logging output.
3078         }
3079 
3080         allocate_dummy_regions();
3081 
3082         _allocator->init_mutator_alloc_regions();
3083 
3084         expand_heap_after_young_collection();
3085 
3086         double sample_end_time_sec = os::elapsedTime();
3087         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3088         policy()->record_collection_pause_end(pause_time_ms);
3089       }
3090 
3091       verify_after_young_collection(verify_type);
3092 
3093       gc_epilogue(false);
3094     }
3095 
3096     // Print the remainder of the GC log output.
3097     if (evacuation_failed()) {
3098       log_info(gc)("To-space exhausted");
3099     }
3100 
3101     policy()->print_phases();
3102     heap_transition.print();
3103 
3104     _hrm->verify_optional();
3105     _verifier->verify_region_sets_optional();
3106 
3107     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3108     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3109 
3110     print_heap_after_gc();
3111     print_heap_regions();
3112     trace_heap_after_gc(_gc_tracer_stw);
3113 
3114     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3115     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3116     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3117     // before any GC notifications are raised.
3118     g1mm()->update_sizes();
3119 
3120     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3121     _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3122     _gc_timer_stw->register_gc_end();
3123     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3124   }
3125   // It should now be safe to tell the concurrent mark thread to start
3126   // without its logging output interfering with the logging output
3127   // that came from the pause.
3128 
3129   if (should_start_conc_mark) {
3130     // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3131     // thread(s) could be running concurrently with us. Make sure that anything
3132     // after this point does not assume that we are the only GC thread running.
3133     // Note: of course, the actual marking work will not start until the safepoint
3134     // itself is released in SuspendibleThreadSet::desynchronize().
3135     do_concurrent_mark();
3136     ConcurrentGCBreakpoints::notify_idle_to_active();
3137   }
3138 }
3139 
3140 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3141   G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3142   workers()->run_task(&rsfp_task);
3143 }
3144 
3145 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3146   double remove_self_forwards_start = os::elapsedTime();
3147 
3148   remove_self_forwarding_pointers(rdcqs);
3149   _preserved_marks_set.restore(workers());
3150 
3151   phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3152 }
3153 
3154 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3155   if (!_evacuation_failed) {
3156     _evacuation_failed = true;
3157   }
3158 
3159   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3160   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3161 }
3162 
3163 bool G1ParEvacuateFollowersClosure::offer_termination() {
3164   EventGCPhaseParallel event;
3165   G1ParScanThreadState* const pss = par_scan_state();
3166   start_term_time();
3167   const bool res = terminator()->offer_termination();
3168   end_term_time();
3169   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3170   return res;
3171 }
3172 
3173 void G1ParEvacuateFollowersClosure::do_void() {
3174   EventGCPhaseParallel event;
3175   G1ParScanThreadState* const pss = par_scan_state();
3176   pss->trim_queue();
3177   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3178   do {
3179     EventGCPhaseParallel event;
3180     pss->steal_and_trim_queue(queues());
3181     event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3182   } while (!offer_termination());
3183 }
3184 
3185 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3186                                         bool class_unloading_occurred) {
3187   uint num_workers = workers()->active_workers();
3188   G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3189   workers()->run_task(&unlink_task);
3190 }
3191 
3192 // Clean string dedup data structures.
3193 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3194 // record the durations of the phases. Hence the almost-copy.
3195 class G1StringDedupCleaningTask : public AbstractGangTask {
3196   BoolObjectClosure* _is_alive;
3197   OopClosure* _keep_alive;
3198   G1GCPhaseTimes* _phase_times;
3199 
3200 public:
3201   G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3202                             OopClosure* keep_alive,
3203                             G1GCPhaseTimes* phase_times) :
3204     AbstractGangTask("Partial Cleaning Task"),
3205     _is_alive(is_alive),
3206     _keep_alive(keep_alive),
3207     _phase_times(phase_times)
3208   {
3209     assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3210     StringDedup::gc_prologue(true);
3211   }
3212 
3213   ~G1StringDedupCleaningTask() {
3214     StringDedup::gc_epilogue();
3215   }
3216 
3217   void work(uint worker_id) {
3218     StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3219     {
3220       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3221       StringDedupQueue::unlink_or_oops_do(&cl);
3222     }
3223     {
3224       G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3225       StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3226     }
3227   }
3228 };
3229 
3230 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3231                                             OopClosure* keep_alive,
3232                                             G1GCPhaseTimes* phase_times) {
3233   G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3234   workers()->run_task(&cl);
3235 }
3236 
3237 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3238  private:
3239   G1RedirtyCardsQueueSet* _qset;
3240   G1CollectedHeap* _g1h;
3241   BufferNode* volatile _nodes;
3242 
3243   void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3244     size_t buffer_size = _qset->buffer_size();
3245     BufferNode* next = Atomic::load(&_nodes);
3246     while (next != NULL) {
3247       BufferNode* node = next;
3248       next = Atomic::cmpxchg(&_nodes, node, node->next());
3249       if (next == node) {
3250         cl->apply_to_buffer(node, buffer_size, worker_id);
3251         next = node->next();
3252       }
3253     }
3254   }
3255 
3256  public:
3257   G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3258     AbstractGangTask("Redirty Cards"),
3259     _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3260 
3261   virtual void work(uint worker_id) {
3262     G1GCPhaseTimes* p = _g1h->phase_times();
3263     G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3264 
3265     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3266     par_apply(&cl, worker_id);
3267 
3268     p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3269   }
3270 };
3271 
3272 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3273   double redirty_logged_cards_start = os::elapsedTime();
3274 
3275   G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3276   workers()->run_task(&redirty_task);
3277 
3278   G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3279   dcq.merge_bufferlists(rdcqs);
3280 
3281   phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3282 }
3283 
3284 // Weak Reference Processing support
3285 
3286 bool G1STWIsAliveClosure::do_object_b(oop p) {
3287   // An object is reachable if it is outside the collection set,
3288   // or is inside and copied.
3289   return !_g1h->is_in_cset(p) || p->is_forwarded();
3290 }
3291 
3292 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3293   assert(obj != NULL, "must not be NULL");
3294   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3295   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3296   // may falsely indicate that this is not the case here: however the collection set only
3297   // contains old regions when concurrent mark is not running.
3298   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3299 }
3300 
3301 // Non Copying Keep Alive closure
3302 class G1KeepAliveClosure: public OopClosure {
3303   G1CollectedHeap*_g1h;
3304 public:
3305   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3306   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3307   void do_oop(oop* p) {
3308     oop obj = *p;
3309     assert(obj != NULL, "the caller should have filtered out NULL values");
3310 
3311     const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3312     if (!region_attr.is_in_cset_or_humongous()) {
3313       return;
3314     }
3315     if (region_attr.is_in_cset()) {
3316       assert( obj->is_forwarded(), "invariant" );
3317       *p = obj->forwardee();
3318     } else {
3319       assert(!obj->is_forwarded(), "invariant" );
3320       assert(region_attr.is_humongous(),
3321              "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3322      _g1h->set_humongous_is_live(obj);
3323     }
3324   }
3325 };
3326 
3327 // Copying Keep Alive closure - can be called from both
3328 // serial and parallel code as long as different worker
3329 // threads utilize different G1ParScanThreadState instances
3330 // and different queues.
3331 
3332 class G1CopyingKeepAliveClosure: public OopClosure {
3333   G1CollectedHeap*         _g1h;
3334   G1ParScanThreadState*    _par_scan_state;
3335 
3336 public:
3337   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3338                             G1ParScanThreadState* pss):
3339     _g1h(g1h),
3340     _par_scan_state(pss)
3341   {}
3342 
3343   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3344   virtual void do_oop(      oop* p) { do_oop_work(p); }
3345 
3346   template <class T> void do_oop_work(T* p) {
3347     oop obj = RawAccess<>::oop_load(p);
3348 
3349     if (_g1h->is_in_cset_or_humongous(obj)) {
3350       // If the referent object has been forwarded (either copied
3351       // to a new location or to itself in the event of an
3352       // evacuation failure) then we need to update the reference
3353       // field and, if both reference and referent are in the G1
3354       // heap, update the RSet for the referent.
3355       //
3356       // If the referent has not been forwarded then we have to keep
3357       // it alive by policy. Therefore we have copy the referent.
3358       //
3359       // When the queue is drained (after each phase of reference processing)
3360       // the object and it's followers will be copied, the reference field set
3361       // to point to the new location, and the RSet updated.
3362       _par_scan_state->push_on_queue(ScannerTask(p));
3363     }
3364   }
3365 };
3366 
3367 // Serial drain queue closure. Called as the 'complete_gc'
3368 // closure for each discovered list in some of the
3369 // reference processing phases.
3370 
3371 class G1STWDrainQueueClosure: public VoidClosure {
3372 protected:
3373   G1CollectedHeap* _g1h;
3374   G1ParScanThreadState* _par_scan_state;
3375 
3376   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3377 
3378 public:
3379   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3380     _g1h(g1h),
3381     _par_scan_state(pss)
3382   { }
3383 
3384   void do_void() {
3385     G1ParScanThreadState* const pss = par_scan_state();
3386     pss->trim_queue();
3387   }
3388 };
3389 
3390 // Parallel Reference Processing closures
3391 
3392 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3393 // processing during G1 evacuation pauses.
3394 
3395 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3396 private:
3397   G1CollectedHeap*          _g1h;
3398   G1ParScanThreadStateSet*  _pss;
3399   G1ScannerTasksQueueSet*   _queues;
3400   WorkGang*                 _workers;
3401 
3402 public:
3403   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3404                            G1ParScanThreadStateSet* per_thread_states,
3405                            WorkGang* workers,
3406                            G1ScannerTasksQueueSet *task_queues) :
3407     _g1h(g1h),
3408     _pss(per_thread_states),
3409     _queues(task_queues),
3410     _workers(workers)
3411   {
3412     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3413   }
3414 
3415   // Executes the given task using concurrent marking worker threads.
3416   virtual void execute(ProcessTask& task, uint ergo_workers);
3417 };
3418 
3419 // Gang task for possibly parallel reference processing
3420 
3421 class G1STWRefProcTaskProxy: public AbstractGangTask {
3422   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3423   ProcessTask&     _proc_task;
3424   G1CollectedHeap* _g1h;
3425   G1ParScanThreadStateSet* _pss;
3426   G1ScannerTasksQueueSet* _task_queues;
3427   TaskTerminator* _terminator;
3428 
3429 public:
3430   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3431                         G1CollectedHeap* g1h,
3432                         G1ParScanThreadStateSet* per_thread_states,
3433                         G1ScannerTasksQueueSet *task_queues,
3434                         TaskTerminator* terminator) :
3435     AbstractGangTask("Process reference objects in parallel"),
3436     _proc_task(proc_task),
3437     _g1h(g1h),
3438     _pss(per_thread_states),
3439     _task_queues(task_queues),
3440     _terminator(terminator)
3441   {}
3442 
3443   virtual void work(uint worker_id) {
3444     // The reference processing task executed by a single worker.
3445     ResourceMark rm;
3446 
3447     G1STWIsAliveClosure is_alive(_g1h);
3448 
3449     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3450     pss->set_ref_discoverer(NULL);
3451 
3452     // Keep alive closure.
3453     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3454 
3455     // Complete GC closure
3456     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3457 
3458     // Call the reference processing task's work routine.
3459     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3460 
3461     // Note we cannot assert that the refs array is empty here as not all
3462     // of the processing tasks (specifically phase2 - pp2_work) execute
3463     // the complete_gc closure (which ordinarily would drain the queue) so
3464     // the queue may not be empty.
3465   }
3466 };
3467 
3468 // Driver routine for parallel reference processing.
3469 // Creates an instance of the ref processing gang
3470 // task and has the worker threads execute it.
3471 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3472   assert(_workers != NULL, "Need parallel worker threads.");
3473 
3474   assert(_workers->active_workers() >= ergo_workers,
3475          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3476          ergo_workers, _workers->active_workers());
3477   TaskTerminator terminator(ergo_workers, _queues);
3478   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3479 
3480   _workers->run_task(&proc_task_proxy, ergo_workers);
3481 }
3482 
3483 // End of weak reference support closures
3484 
3485 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3486   double ref_proc_start = os::elapsedTime();
3487 
3488   ReferenceProcessor* rp = _ref_processor_stw;
3489   assert(rp->discovery_enabled(), "should have been enabled");
3490 
3491   // Closure to test whether a referent is alive.
3492   G1STWIsAliveClosure is_alive(this);
3493 
3494   // Even when parallel reference processing is enabled, the processing
3495   // of JNI refs is serial and performed serially by the current thread
3496   // rather than by a worker. The following PSS will be used for processing
3497   // JNI refs.
3498 
3499   // Use only a single queue for this PSS.
3500   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3501   pss->set_ref_discoverer(NULL);
3502   assert(pss->queue_is_empty(), "pre-condition");
3503 
3504   // Keep alive closure.
3505   G1CopyingKeepAliveClosure keep_alive(this, pss);
3506 
3507   // Serial Complete GC closure
3508   G1STWDrainQueueClosure drain_queue(this, pss);
3509 
3510   // Setup the soft refs policy...
3511   rp->setup_policy(false);
3512 
3513   ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3514 
3515   ReferenceProcessorStats stats;
3516   if (!rp->processing_is_mt()) {
3517     // Serial reference processing...
3518     stats = rp->process_discovered_references(&is_alive,
3519                                               &keep_alive,
3520                                               &drain_queue,
3521                                               NULL,
3522                                               pt);
3523   } else {
3524     uint no_of_gc_workers = workers()->active_workers();
3525 
3526     // Parallel reference processing
3527     assert(no_of_gc_workers <= rp->max_num_queues(),
3528            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3529            no_of_gc_workers,  rp->max_num_queues());
3530 
3531     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3532     stats = rp->process_discovered_references(&is_alive,
3533                                               &keep_alive,
3534                                               &drain_queue,
3535                                               &par_task_executor,
3536                                               pt);
3537   }
3538 
3539   _gc_tracer_stw->report_gc_reference_stats(stats);
3540 
3541   // We have completed copying any necessary live referent objects.
3542   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3543 
3544   make_pending_list_reachable();
3545 
3546   assert(!rp->discovery_enabled(), "Postcondition");
3547   rp->verify_no_references_recorded();
3548 
3549   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3550   phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3551 }
3552 
3553 void G1CollectedHeap::make_pending_list_reachable() {
3554   if (collector_state()->in_concurrent_start_gc()) {
3555     oop pll_head = Universe::reference_pending_list();
3556     if (pll_head != NULL) {
3557       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3558       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3559     }
3560   }
3561 }
3562 
3563 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3564   Ticks start = Ticks::now();
3565   per_thread_states->flush();
3566   phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3567 }
3568 
3569 class G1PrepareEvacuationTask : public AbstractGangTask {
3570   class G1PrepareRegionsClosure : public HeapRegionClosure {
3571     G1CollectedHeap* _g1h;
3572     G1PrepareEvacuationTask* _parent_task;
3573     size_t _worker_humongous_total;
3574     size_t _worker_humongous_candidates;
3575 
3576     bool humongous_region_is_candidate(HeapRegion* region) const {
3577       assert(region->is_starts_humongous(), "Must start a humongous object");
3578 
3579       oop obj = oop(region->bottom());
3580 
3581       // Dead objects cannot be eager reclaim candidates. Due to class
3582       // unloading it is unsafe to query their classes so we return early.
3583       if (_g1h->is_obj_dead(obj, region)) {
3584         return false;
3585       }
3586 
3587       // If we do not have a complete remembered set for the region, then we can
3588       // not be sure that we have all references to it.
3589       if (!region->rem_set()->is_complete()) {
3590         return false;
3591       }
3592       // Candidate selection must satisfy the following constraints
3593       // while concurrent marking is in progress:
3594       //
3595       // * In order to maintain SATB invariants, an object must not be
3596       // reclaimed if it was allocated before the start of marking and
3597       // has not had its references scanned.  Such an object must have
3598       // its references (including type metadata) scanned to ensure no
3599       // live objects are missed by the marking process.  Objects
3600       // allocated after the start of concurrent marking don't need to
3601       // be scanned.
3602       //
3603       // * An object must not be reclaimed if it is on the concurrent
3604       // mark stack.  Objects allocated after the start of concurrent
3605       // marking are never pushed on the mark stack.
3606       //
3607       // Nominating only objects allocated after the start of concurrent
3608       // marking is sufficient to meet both constraints.  This may miss
3609       // some objects that satisfy the constraints, but the marking data
3610       // structures don't support efficiently performing the needed
3611       // additional tests or scrubbing of the mark stack.
3612       //
3613       // However, we presently only nominate is_typeArray() objects.
3614       // A humongous object containing references induces remembered
3615       // set entries on other regions.  In order to reclaim such an
3616       // object, those remembered sets would need to be cleaned up.
3617       //
3618       // We also treat is_typeArray() objects specially, allowing them
3619       // to be reclaimed even if allocated before the start of
3620       // concurrent mark.  For this we rely on mark stack insertion to
3621       // exclude is_typeArray() objects, preventing reclaiming an object
3622       // that is in the mark stack.  We also rely on the metadata for
3623       // such objects to be built-in and so ensured to be kept live.
3624       // Frequent allocation and drop of large binary blobs is an
3625       // important use case for eager reclaim, and this special handling
3626       // may reduce needed headroom.
3627 
3628       return obj->is_typeArray() &&
3629              _g1h->is_potential_eager_reclaim_candidate(region);
3630     }
3631 
3632   public:
3633     G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3634       _g1h(g1h),
3635       _parent_task(parent_task),
3636       _worker_humongous_total(0),
3637       _worker_humongous_candidates(0) { }
3638 
3639     ~G1PrepareRegionsClosure() {
3640       _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3641       _parent_task->add_humongous_total(_worker_humongous_total);
3642     }
3643 
3644     virtual bool do_heap_region(HeapRegion* hr) {
3645       // First prepare the region for scanning
3646       _g1h->rem_set()->prepare_region_for_scan(hr);
3647 
3648       // Now check if region is a humongous candidate
3649       if (!hr->is_starts_humongous()) {
3650         _g1h->register_region_with_region_attr(hr);
3651         return false;
3652       }
3653 
3654       uint index = hr->hrm_index();
3655       if (humongous_region_is_candidate(hr)) {
3656         _g1h->set_humongous_reclaim_candidate(index, true);
3657         _g1h->register_humongous_region_with_region_attr(index);
3658         _worker_humongous_candidates++;
3659         // We will later handle the remembered sets of these regions.
3660       } else {
3661         _g1h->set_humongous_reclaim_candidate(index, false);
3662         _g1h->register_region_with_region_attr(hr);
3663       }
3664       _worker_humongous_total++;
3665 
3666       return false;
3667     }
3668   };
3669 
3670   G1CollectedHeap* _g1h;
3671   HeapRegionClaimer _claimer;
3672   volatile size_t _humongous_total;
3673   volatile size_t _humongous_candidates;
3674 public:
3675   G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3676     AbstractGangTask("Prepare Evacuation"),
3677     _g1h(g1h),
3678     _claimer(_g1h->workers()->active_workers()),
3679     _humongous_total(0),
3680     _humongous_candidates(0) { }
3681 
3682   ~G1PrepareEvacuationTask() {
3683     _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3684   }
3685 
3686   void work(uint worker_id) {
3687     G1PrepareRegionsClosure cl(_g1h, this);
3688     _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3689   }
3690 
3691   void add_humongous_candidates(size_t candidates) {
3692     Atomic::add(&_humongous_candidates, candidates);
3693   }
3694 
3695   void add_humongous_total(size_t total) {
3696     Atomic::add(&_humongous_total, total);
3697   }
3698 
3699   size_t humongous_candidates() {
3700     return _humongous_candidates;
3701   }
3702 
3703   size_t humongous_total() {
3704     return _humongous_total;
3705   }
3706 };
3707 
3708 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3709   _bytes_used_during_gc = 0;
3710 
3711   _expand_heap_after_alloc_failure = true;
3712   _evacuation_failed = false;
3713 
3714   // Disable the hot card cache.
3715   _hot_card_cache->reset_hot_cache_claimed_index();
3716   _hot_card_cache->set_use_cache(false);
3717 
3718   // Initialize the GC alloc regions.
3719   _allocator->init_gc_alloc_regions(evacuation_info);
3720 
3721   {
3722     Ticks start = Ticks::now();
3723     rem_set()->prepare_for_scan_heap_roots();
3724     phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3725   }
3726 
3727   {
3728     G1PrepareEvacuationTask g1_prep_task(this);
3729     Tickspan task_time = run_task_timed(&g1_prep_task);
3730 
3731     phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3732                                            g1_prep_task.humongous_total(),
3733                                            g1_prep_task.humongous_candidates());
3734   }
3735 
3736   assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3737   _preserved_marks_set.assert_empty();
3738 
3739 #if COMPILER2_OR_JVMCI
3740   DerivedPointerTable::clear();
3741 #endif
3742 
3743   // Concurrent start needs claim bits to keep track of the marked-through CLDs.
3744   if (collector_state()->in_concurrent_start_gc()) {
3745     concurrent_mark()->pre_concurrent_start();
3746 
3747     double start_clear_claimed_marks = os::elapsedTime();
3748 
3749     ClassLoaderDataGraph::clear_claimed_marks();
3750 
3751     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3752     phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3753   }
3754 
3755   // Should G1EvacuationFailureALot be in effect for this GC?
3756   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3757 }
3758 
3759 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3760 protected:
3761   G1CollectedHeap* _g1h;
3762   G1ParScanThreadStateSet* _per_thread_states;
3763   G1ScannerTasksQueueSet* _task_queues;
3764   TaskTerminator _terminator;
3765   uint _num_workers;
3766 
3767   void evacuate_live_objects(G1ParScanThreadState* pss,
3768                              uint worker_id,
3769                              G1GCPhaseTimes::GCParPhases objcopy_phase,
3770                              G1GCPhaseTimes::GCParPhases termination_phase) {
3771     G1GCPhaseTimes* p = _g1h->phase_times();
3772 
3773     Ticks start = Ticks::now();
3774     G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3775     cl.do_void();
3776 
3777     assert(pss->queue_is_empty(), "should be empty");
3778 
3779     Tickspan evac_time = (Ticks::now() - start);
3780     p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3781 
3782     if (termination_phase == G1GCPhaseTimes::Termination) {
3783       p->record_time_secs(termination_phase, worker_id, cl.term_time());
3784       p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3785     } else {
3786       p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3787       p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3788     }
3789     assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3790   }
3791 
3792   virtual void start_work(uint worker_id) { }
3793 
3794   virtual void end_work(uint worker_id) { }
3795 
3796   virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3797 
3798   virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3799 
3800 public:
3801   G1EvacuateRegionsBaseTask(const char* name,
3802                             G1ParScanThreadStateSet* per_thread_states,
3803                             G1ScannerTasksQueueSet* task_queues,
3804                             uint num_workers) :
3805     AbstractGangTask(name),
3806     _g1h(G1CollectedHeap::heap()),
3807     _per_thread_states(per_thread_states),
3808     _task_queues(task_queues),
3809     _terminator(num_workers, _task_queues),
3810     _num_workers(num_workers)
3811   { }
3812 
3813   void work(uint worker_id) {
3814     start_work(worker_id);
3815 
3816     {
3817       ResourceMark rm;
3818 
3819       G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3820       pss->set_ref_discoverer(_g1h->ref_processor_stw());
3821 
3822       scan_roots(pss, worker_id);
3823       evacuate_live_objects(pss, worker_id);
3824     }
3825 
3826     end_work(worker_id);
3827   }
3828 };
3829 
3830 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3831   G1RootProcessor* _root_processor;
3832 
3833   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3834     _root_processor->evacuate_roots(pss, worker_id);
3835     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3836     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3837   }
3838 
3839   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3840     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3841   }
3842 
3843   void start_work(uint worker_id) {
3844     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3845   }
3846 
3847   void end_work(uint worker_id) {
3848     _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3849   }
3850 
3851 public:
3852   G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3853                         G1ParScanThreadStateSet* per_thread_states,
3854                         G1ScannerTasksQueueSet* task_queues,
3855                         G1RootProcessor* root_processor,
3856                         uint num_workers) :
3857     G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3858     _root_processor(root_processor)
3859   { }
3860 };
3861 
3862 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3863   G1GCPhaseTimes* p = phase_times();
3864 
3865   {
3866     Ticks start = Ticks::now();
3867     rem_set()->merge_heap_roots(true /* initial_evacuation */);
3868     p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3869   }
3870 
3871   Tickspan task_time;
3872   const uint num_workers = workers()->active_workers();
3873 
3874   Ticks start_processing = Ticks::now();
3875   {
3876     G1RootProcessor root_processor(this, num_workers);
3877     G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3878     task_time = run_task_timed(&g1_par_task);
3879     // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3880     // To extract its code root fixup time we measure total time of this scope and
3881     // subtract from the time the WorkGang task took.
3882   }
3883   Tickspan total_processing = Ticks::now() - start_processing;
3884 
3885   p->record_initial_evac_time(task_time.seconds() * 1000.0);
3886   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3887 }
3888 
3889 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3890 
3891   void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3892     _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3893     _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3894   }
3895 
3896   void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3897     G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3898   }
3899 
3900 public:
3901   G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3902                                 G1ScannerTasksQueueSet* queues,
3903                                 uint num_workers) :
3904     G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3905   }
3906 };
3907 
3908 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3909   class G1MarkScope : public MarkScope { };
3910 
3911   Tickspan task_time;
3912 
3913   Ticks start_processing = Ticks::now();
3914   {
3915     G1MarkScope code_mark_scope;
3916     G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3917     task_time = run_task_timed(&task);
3918     // See comment in evacuate_collection_set() for the reason of the scope.
3919   }
3920   Tickspan total_processing = Ticks::now() - start_processing;
3921 
3922   G1GCPhaseTimes* p = phase_times();
3923   p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3924 }
3925 
3926 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3927   const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3928 
3929   while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3930 
3931     double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3932     double time_left_ms = MaxGCPauseMillis - time_used_ms;
3933 
3934     if (time_left_ms < 0 ||
3935         !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3936       log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3937                                 _collection_set.optional_region_length(), time_left_ms);
3938       break;
3939     }
3940 
3941     {
3942       Ticks start = Ticks::now();
3943       rem_set()->merge_heap_roots(false /* initial_evacuation */);
3944       phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3945     }
3946 
3947     {
3948       Ticks start = Ticks::now();
3949       evacuate_next_optional_regions(per_thread_states);
3950       phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3951     }
3952   }
3953 
3954   _collection_set.abandon_optional_collection_set(per_thread_states);
3955 }
3956 
3957 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3958                                                    G1RedirtyCardsQueueSet* rdcqs,
3959                                                    G1ParScanThreadStateSet* per_thread_states) {
3960   G1GCPhaseTimes* p = phase_times();
3961 
3962   rem_set()->cleanup_after_scan_heap_roots();
3963 
3964   // Process any discovered reference objects - we have
3965   // to do this _before_ we retire the GC alloc regions
3966   // as we may have to copy some 'reachable' referent
3967   // objects (and their reachable sub-graphs) that were
3968   // not copied during the pause.
3969   process_discovered_references(per_thread_states);
3970 
3971   G1STWIsAliveClosure is_alive(this);
3972   G1KeepAliveClosure keep_alive(this);
3973 
3974   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
3975 
3976   if (G1StringDedup::is_enabled()) {
3977     double string_dedup_time_ms = os::elapsedTime();
3978 
3979     string_dedup_cleaning(&is_alive, &keep_alive, p);
3980 
3981     double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3982     p->record_string_deduplication_time(string_cleanup_time_ms);
3983   }
3984 
3985   _allocator->release_gc_alloc_regions(evacuation_info);
3986 
3987   if (evacuation_failed()) {
3988     restore_after_evac_failure(rdcqs);
3989 
3990     // Reset the G1EvacuationFailureALot counters and flags
3991     NOT_PRODUCT(reset_evacuation_should_fail();)
3992 
3993     double recalculate_used_start = os::elapsedTime();
3994     set_used(recalculate_used());
3995     p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3996 
3997     if (_archive_allocator != NULL) {
3998       _archive_allocator->clear_used();
3999     }
4000     for (uint i = 0; i < ParallelGCThreads; i++) {
4001       if (_evacuation_failed_info_array[i].has_failed()) {
4002         _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4003       }
4004     }
4005   } else {
4006     // The "used" of the the collection set have already been subtracted
4007     // when they were freed.  Add in the bytes used.
4008     increase_used(_bytes_used_during_gc);
4009   }
4010 
4011   _preserved_marks_set.assert_empty();
4012 
4013   merge_per_thread_state_info(per_thread_states);
4014 
4015   // Reset and re-enable the hot card cache.
4016   // Note the counts for the cards in the regions in the
4017   // collection set are reset when the collection set is freed.
4018   _hot_card_cache->reset_hot_cache();
4019   _hot_card_cache->set_use_cache(true);
4020 
4021   purge_code_root_memory();
4022 
4023   redirty_logged_cards(rdcqs);
4024 
4025   free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4026 
4027   eagerly_reclaim_humongous_regions();
4028 
4029   record_obj_copy_mem_stats();
4030 
4031   evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4032   evacuation_info.set_bytes_used(_bytes_used_during_gc);
4033 
4034 #if COMPILER2_OR_JVMCI
4035   double start = os::elapsedTime();
4036   DerivedPointerTable::update_pointers();
4037   phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4038 #endif
4039   policy()->print_age_table();
4040 }
4041 
4042 void G1CollectedHeap::record_obj_copy_mem_stats() {
4043   policy()->old_gen_alloc_tracker()->
4044     add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4045 
4046   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4047                                                create_g1_evac_summary(&_old_evac_stats));
4048 }
4049 
4050 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4051   assert(!hr->is_free(), "the region should not be free");
4052   assert(!hr->is_empty(), "the region should not be empty");
4053   assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4054 
4055   if (G1VerifyBitmaps) {
4056     MemRegion mr(hr->bottom(), hr->end());
4057     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4058   }
4059 
4060   // Clear the card counts for this region.
4061   // Note: we only need to do this if the region is not young
4062   // (since we don't refine cards in young regions).
4063   if (!hr->is_young()) {
4064     _hot_card_cache->reset_card_counts(hr);
4065   }
4066 
4067   // Reset region metadata to allow reuse.
4068   hr->hr_clear(true /* clear_space */);
4069   _policy->remset_tracker()->update_at_free(hr);
4070 
4071   if (free_list != NULL) {
4072     free_list->add_ordered(hr);
4073   }
4074 }
4075 
4076 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4077                                             FreeRegionList* free_list) {
4078   assert(hr->is_humongous(), "this is only for humongous regions");
4079   assert(free_list != NULL, "pre-condition");
4080   hr->clear_humongous();
4081   free_region(hr, free_list);
4082 }
4083 
4084 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4085                                            const uint humongous_regions_removed) {
4086   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4087     MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4088     _old_set.bulk_remove(old_regions_removed);
4089     _humongous_set.bulk_remove(humongous_regions_removed);
4090   }
4091 
4092 }
4093 
4094 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4095   assert(list != NULL, "list can't be null");
4096   if (!list->is_empty()) {
4097     MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4098     _hrm->insert_list_into_free_list(list);
4099   }
4100 }
4101 
4102 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4103   decrease_used(bytes);
4104 }
4105 
4106 class G1FreeCollectionSetTask : public AbstractGangTask {
4107   // Helper class to keep statistics for the collection set freeing
4108   class FreeCSetStats {
4109     size_t _before_used_bytes;   // Usage in regions successfully evacutate
4110     size_t _after_used_bytes;    // Usage in regions failing evacuation
4111     size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4112     size_t _failure_used_words;  // Live size in failed regions
4113     size_t _failure_waste_words; // Wasted size in failed regions
4114     size_t _rs_length;           // Remembered set size
4115     uint _regions_freed;         // Number of regions freed
4116   public:
4117     FreeCSetStats() :
4118         _before_used_bytes(0),
4119         _after_used_bytes(0),
4120         _bytes_allocated_in_old_since_last_gc(0),
4121         _failure_used_words(0),
4122         _failure_waste_words(0),
4123         _rs_length(0),
4124         _regions_freed(0) { }
4125 
4126     void merge_stats(FreeCSetStats* other) {
4127       assert(other != NULL, "invariant");
4128       _before_used_bytes += other->_before_used_bytes;
4129       _after_used_bytes += other->_after_used_bytes;
4130       _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4131       _failure_used_words += other->_failure_used_words;
4132       _failure_waste_words += other->_failure_waste_words;
4133       _rs_length += other->_rs_length;
4134       _regions_freed += other->_regions_freed;
4135     }
4136 
4137     void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4138       evacuation_info->set_regions_freed(_regions_freed);
4139       evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4140 
4141       g1h->decrement_summary_bytes(_before_used_bytes);
4142       g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4143 
4144       G1Policy *policy = g1h->policy();
4145       policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4146       policy->record_rs_length(_rs_length);
4147       policy->cset_regions_freed();
4148     }
4149 
4150     void account_failed_region(HeapRegion* r) {
4151       size_t used_words = r->marked_bytes() / HeapWordSize;
4152       _failure_used_words += used_words;
4153       _failure_waste_words += HeapRegion::GrainWords - used_words;
4154       _after_used_bytes += r->used();
4155 
4156       // When moving a young gen region to old gen, we "allocate" that whole
4157       // region there. This is in addition to any already evacuated objects.
4158       // Notify the policy about that. Old gen regions do not cause an
4159       // additional allocation: both the objects still in the region and the
4160       // ones already moved are accounted for elsewhere.
4161       if (r->is_young()) {
4162         _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4163       }
4164     }
4165 
4166     void account_evacuated_region(HeapRegion* r) {
4167       _before_used_bytes += r->used();
4168       _regions_freed += 1;
4169     }
4170 
4171     void account_rs_length(HeapRegion* r) {
4172       _rs_length += r->rem_set()->occupied();
4173     }
4174   };
4175 
4176   // Closure applied to all regions in the collection set.
4177   class FreeCSetClosure : public HeapRegionClosure {
4178     // Helper to send JFR events for regions.
4179     class JFREventForRegion {
4180       EventGCPhaseParallel _event;
4181     public:
4182       JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4183         _event.set_gcId(GCId::current());
4184         _event.set_gcWorkerId(worker_id);
4185         if (region->is_young()) {
4186           _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4187         } else {
4188           _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4189         }
4190       }
4191 
4192       ~JFREventForRegion() {
4193         _event.commit();
4194       }
4195     };
4196 
4197     // Helper to do timing for region work.
4198     class TimerForRegion {
4199       Tickspan& _time;
4200       Ticks     _start_time;
4201     public:
4202       TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4203       ~TimerForRegion() {
4204         _time += Ticks::now() - _start_time;
4205       }
4206     };
4207 
4208     // FreeCSetClosure members
4209     G1CollectedHeap* _g1h;
4210     const size_t*    _surviving_young_words;
4211     uint             _worker_id;
4212     Tickspan         _young_time;
4213     Tickspan         _non_young_time;
4214     FreeCSetStats*   _stats;
4215 
4216     void assert_in_cset(HeapRegion* r) {
4217       assert(r->young_index_in_cset() != 0 &&
4218              (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4219              "Young index %u is wrong for region %u of type %s with %u young regions",
4220              r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4221     }
4222 
4223     void handle_evacuated_region(HeapRegion* r) {
4224       assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4225       stats()->account_evacuated_region(r);
4226 
4227       // Free the region and and its remembered set.
4228       _g1h->free_region(r, NULL);
4229     }
4230 
4231     void handle_failed_region(HeapRegion* r) {
4232       // Do some allocation statistics accounting. Regions that failed evacuation
4233       // are always made old, so there is no need to update anything in the young
4234       // gen statistics, but we need to update old gen statistics.
4235       stats()->account_failed_region(r);
4236 
4237       // Update the region state due to the failed evacuation.
4238       r->handle_evacuation_failure();
4239 
4240       // Add region to old set, need to hold lock.
4241       MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4242       _g1h->old_set_add(r);
4243     }
4244 
4245     Tickspan& timer_for_region(HeapRegion* r) {
4246       return r->is_young() ? _young_time : _non_young_time;
4247     }
4248 
4249     FreeCSetStats* stats() {
4250       return _stats;
4251     }
4252   public:
4253     FreeCSetClosure(const size_t* surviving_young_words,
4254                     uint worker_id,
4255                     FreeCSetStats* stats) :
4256         HeapRegionClosure(),
4257         _g1h(G1CollectedHeap::heap()),
4258         _surviving_young_words(surviving_young_words),
4259         _worker_id(worker_id),
4260         _young_time(),
4261         _non_young_time(),
4262         _stats(stats) { }
4263 
4264     virtual bool do_heap_region(HeapRegion* r) {
4265       assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4266       JFREventForRegion event(r, _worker_id);
4267       TimerForRegion timer(timer_for_region(r));
4268 
4269       _g1h->clear_region_attr(r);
4270       stats()->account_rs_length(r);
4271 
4272       if (r->is_young()) {
4273         assert_in_cset(r);
4274         r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4275       }
4276 
4277       if (r->evacuation_failed()) {
4278         handle_failed_region(r);
4279       } else {
4280         handle_evacuated_region(r);
4281       }
4282       assert(!_g1h->is_on_master_free_list(r), "sanity");
4283 
4284       return false;
4285     }
4286 
4287     void report_timing(Tickspan parallel_time) {
4288       G1GCPhaseTimes* pt = _g1h->phase_times();
4289       pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4290       if (_young_time.value() > 0) {
4291         pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4292       }
4293       if (_non_young_time.value() > 0) {
4294         pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4295       }
4296     }
4297   };
4298 
4299   // G1FreeCollectionSetTask members
4300   G1CollectedHeap*  _g1h;
4301   G1EvacuationInfo* _evacuation_info;
4302   FreeCSetStats*    _worker_stats;
4303   HeapRegionClaimer _claimer;
4304   const size_t*     _surviving_young_words;
4305   uint              _active_workers;
4306 
4307   FreeCSetStats* worker_stats(uint worker) {
4308     return &_worker_stats[worker];
4309   }
4310 
4311   void report_statistics() {
4312     // Merge the accounting
4313     FreeCSetStats total_stats;
4314     for (uint worker = 0; worker < _active_workers; worker++) {
4315       total_stats.merge_stats(worker_stats(worker));
4316     }
4317     total_stats.report(_g1h, _evacuation_info);
4318   }
4319 
4320 public:
4321   G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4322       AbstractGangTask("G1 Free Collection Set"),
4323       _g1h(G1CollectedHeap::heap()),
4324       _evacuation_info(evacuation_info),
4325       _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4326       _claimer(active_workers),
4327       _surviving_young_words(surviving_young_words),
4328       _active_workers(active_workers) {
4329     for (uint worker = 0; worker < active_workers; worker++) {
4330       ::new (&_worker_stats[worker]) FreeCSetStats();
4331     }
4332   }
4333 
4334   ~G1FreeCollectionSetTask() {
4335     Ticks serial_time = Ticks::now();
4336     report_statistics();
4337     for (uint worker = 0; worker < _active_workers; worker++) {
4338       _worker_stats[worker].~FreeCSetStats();
4339     }
4340     FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4341     _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4342   }
4343 
4344   virtual void work(uint worker_id) {
4345     EventGCPhaseParallel event;
4346     Ticks start = Ticks::now();
4347     FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4348     _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4349 
4350     // Report the total parallel time along with some more detailed metrics.
4351     cl.report_timing(Ticks::now() - start);
4352     event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4353   }
4354 };
4355 
4356 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4357   _eden.clear();
4358 
4359   // The free collections set is split up in two tasks, the first
4360   // frees the collection set and records what regions are free,
4361   // and the second one rebuilds the free list. This proved to be
4362   // more efficient than adding a sorted list to another.
4363 
4364   Ticks free_cset_start_time = Ticks::now();
4365   {
4366     uint const num_cs_regions = _collection_set.region_length();
4367     uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4368     G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4369 
4370     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4371                         cl.name(), num_workers, num_cs_regions, num_regions());
4372     workers()->run_task(&cl, num_workers);
4373   }
4374 
4375   Ticks free_cset_end_time = Ticks::now();
4376   phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4377 
4378   // Now rebuild the free region list.
4379   hrm()->rebuild_free_list(workers());
4380   phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4381 
4382   collection_set->clear();
4383 }
4384 
4385 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4386  private:
4387   FreeRegionList* _free_region_list;
4388   HeapRegionSet* _proxy_set;
4389   uint _humongous_objects_reclaimed;
4390   uint _humongous_regions_reclaimed;
4391   size_t _freed_bytes;
4392  public:
4393 
4394   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4395     _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4396   }
4397 
4398   virtual bool do_heap_region(HeapRegion* r) {
4399     if (!r->is_starts_humongous()) {
4400       return false;
4401     }
4402 
4403     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4404 
4405     oop obj = (oop)r->bottom();
4406     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4407 
4408     // The following checks whether the humongous object is live are sufficient.
4409     // The main additional check (in addition to having a reference from the roots
4410     // or the young gen) is whether the humongous object has a remembered set entry.
4411     //
4412     // A humongous object cannot be live if there is no remembered set for it
4413     // because:
4414     // - there can be no references from within humongous starts regions referencing
4415     // the object because we never allocate other objects into them.
4416     // (I.e. there are no intra-region references that may be missed by the
4417     // remembered set)
4418     // - as soon there is a remembered set entry to the humongous starts region
4419     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4420     // until the end of a concurrent mark.
4421     //
4422     // It is not required to check whether the object has been found dead by marking
4423     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4424     // all objects allocated during that time are considered live.
4425     // SATB marking is even more conservative than the remembered set.
4426     // So if at this point in the collection there is no remembered set entry,
4427     // nobody has a reference to it.
4428     // At the start of collection we flush all refinement logs, and remembered sets
4429     // are completely up-to-date wrt to references to the humongous object.
4430     //
4431     // Other implementation considerations:
4432     // - never consider object arrays at this time because they would pose
4433     // considerable effort for cleaning up the the remembered sets. This is
4434     // required because stale remembered sets might reference locations that
4435     // are currently allocated into.
4436     uint region_idx = r->hrm_index();
4437     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4438         !r->rem_set()->is_empty()) {
4439       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",
4440                                region_idx,
4441                                (size_t)obj->size() * HeapWordSize,
4442                                p2i(r->bottom()),
4443                                r->rem_set()->occupied(),
4444                                r->rem_set()->strong_code_roots_list_length(),
4445                                next_bitmap->is_marked(r->bottom()),
4446                                g1h->is_humongous_reclaim_candidate(region_idx),
4447                                obj->is_typeArray()
4448                               );
4449       return false;
4450     }
4451 
4452     guarantee(obj->is_typeArray(),
4453               "Only eagerly reclaiming type arrays is supported, but the object "
4454               PTR_FORMAT " is not.", p2i(r->bottom()));
4455 
4456     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",
4457                              region_idx,
4458                              (size_t)obj->size() * HeapWordSize,
4459                              p2i(r->bottom()),
4460                              r->rem_set()->occupied(),
4461                              r->rem_set()->strong_code_roots_list_length(),
4462                              next_bitmap->is_marked(r->bottom()),
4463                              g1h->is_humongous_reclaim_candidate(region_idx),
4464                              obj->is_typeArray()
4465                             );
4466 
4467     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4468     cm->humongous_object_eagerly_reclaimed(r);
4469     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4470            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4471            region_idx,
4472            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4473            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4474     _humongous_objects_reclaimed++;
4475     do {
4476       HeapRegion* next = g1h->next_region_in_humongous(r);
4477       _freed_bytes += r->used();
4478       r->set_containing_set(NULL);
4479       _humongous_regions_reclaimed++;
4480       g1h->free_humongous_region(r, _free_region_list);
4481       r = next;
4482     } while (r != NULL);
4483 
4484     return false;
4485   }
4486 
4487   uint humongous_objects_reclaimed() {
4488     return _humongous_objects_reclaimed;
4489   }
4490 
4491   uint humongous_regions_reclaimed() {
4492     return _humongous_regions_reclaimed;
4493   }
4494 
4495   size_t bytes_freed() const {
4496     return _freed_bytes;
4497   }
4498 };
4499 
4500 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4501   assert_at_safepoint_on_vm_thread();
4502 
4503   if (!G1EagerReclaimHumongousObjects ||
4504       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4505     phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4506     return;
4507   }
4508 
4509   double start_time = os::elapsedTime();
4510 
4511   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4512 
4513   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4514   heap_region_iterate(&cl);
4515 
4516   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4517 
4518   G1HRPrinter* hrp = hr_printer();
4519   if (hrp->is_active()) {
4520     FreeRegionListIterator iter(&local_cleanup_list);
4521     while (iter.more_available()) {
4522       HeapRegion* hr = iter.get_next();
4523       hrp->cleanup(hr);
4524     }
4525   }
4526 
4527   prepend_to_freelist(&local_cleanup_list);
4528   decrement_summary_bytes(cl.bytes_freed());
4529 
4530   phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4531                                                        cl.humongous_objects_reclaimed());
4532 }
4533 
4534 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4535 public:
4536   virtual bool do_heap_region(HeapRegion* r) {
4537     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4538     G1CollectedHeap::heap()->clear_region_attr(r);
4539     r->clear_young_index_in_cset();
4540     return false;
4541   }
4542 };
4543 
4544 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4545   G1AbandonCollectionSetClosure cl;
4546   collection_set_iterate_all(&cl);
4547 
4548   collection_set->clear();
4549   collection_set->stop_incremental_building();
4550 }
4551 
4552 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4553   return _allocator->is_retained_old_region(hr);
4554 }
4555 
4556 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4557   _eden.add(hr);
4558   _policy->set_region_eden(hr);
4559 }
4560 
4561 #ifdef ASSERT
4562 
4563 class NoYoungRegionsClosure: public HeapRegionClosure {
4564 private:
4565   bool _success;
4566 public:
4567   NoYoungRegionsClosure() : _success(true) { }
4568   bool do_heap_region(HeapRegion* r) {
4569     if (r->is_young()) {
4570       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4571                             p2i(r->bottom()), p2i(r->end()));
4572       _success = false;
4573     }
4574     return false;
4575   }
4576   bool success() { return _success; }
4577 };
4578 
4579 bool G1CollectedHeap::check_young_list_empty() {
4580   bool ret = (young_regions_count() == 0);
4581 
4582   NoYoungRegionsClosure closure;
4583   heap_region_iterate(&closure);
4584   ret = ret && closure.success();
4585 
4586   return ret;
4587 }
4588 
4589 #endif // ASSERT
4590 
4591 class TearDownRegionSetsClosure : public HeapRegionClosure {
4592   HeapRegionSet *_old_set;
4593 
4594 public:
4595   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4596 
4597   bool do_heap_region(HeapRegion* r) {
4598     if (r->is_old()) {
4599       _old_set->remove(r);
4600     } else if(r->is_young()) {
4601       r->uninstall_surv_rate_group();
4602     } else {
4603       // We ignore free regions, we'll empty the free list afterwards.
4604       // We ignore humongous and archive regions, we're not tearing down these
4605       // sets.
4606       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4607              "it cannot be another type");
4608     }
4609     return false;
4610   }
4611 
4612   ~TearDownRegionSetsClosure() {
4613     assert(_old_set->is_empty(), "post-condition");
4614   }
4615 };
4616 
4617 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4618   assert_at_safepoint_on_vm_thread();
4619 
4620   if (!free_list_only) {
4621     TearDownRegionSetsClosure cl(&_old_set);
4622     heap_region_iterate(&cl);
4623 
4624     // Note that emptying the _young_list is postponed and instead done as
4625     // the first step when rebuilding the regions sets again. The reason for
4626     // this is that during a full GC string deduplication needs to know if
4627     // a collected region was young or old when the full GC was initiated.
4628   }
4629   _hrm->remove_all_free_regions();
4630 }
4631 
4632 void G1CollectedHeap::increase_used(size_t bytes) {
4633   _summary_bytes_used += bytes;
4634 }
4635 
4636 void G1CollectedHeap::decrease_used(size_t bytes) {
4637   assert(_summary_bytes_used >= bytes,
4638          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4639          _summary_bytes_used, bytes);
4640   _summary_bytes_used -= bytes;
4641 }
4642 
4643 void G1CollectedHeap::set_used(size_t bytes) {
4644   _summary_bytes_used = bytes;
4645 }
4646 
4647 class RebuildRegionSetsClosure : public HeapRegionClosure {
4648 private:
4649   bool _free_list_only;
4650 
4651   HeapRegionSet* _old_set;
4652   HeapRegionManager* _hrm;
4653 
4654   size_t _total_used;
4655 
4656 public:
4657   RebuildRegionSetsClosure(bool free_list_only,
4658                            HeapRegionSet* old_set,
4659                            HeapRegionManager* hrm) :
4660     _free_list_only(free_list_only),
4661     _old_set(old_set), _hrm(hrm), _total_used(0) {
4662     assert(_hrm->num_free_regions() == 0, "pre-condition");
4663     if (!free_list_only) {
4664       assert(_old_set->is_empty(), "pre-condition");
4665     }
4666   }
4667 
4668   bool do_heap_region(HeapRegion* r) {
4669     if (r->is_empty()) {
4670       assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4671       // Add free regions to the free list
4672       r->set_free();
4673       _hrm->insert_into_free_list(r);
4674     } else if (!_free_list_only) {
4675       assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4676 
4677       if (r->is_archive() || r->is_humongous()) {
4678         // We ignore archive and humongous regions. We left these sets unchanged.
4679       } else {
4680         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4681         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4682         r->move_to_old();
4683         _old_set->add(r);
4684       }
4685       _total_used += r->used();
4686     }
4687 
4688     return false;
4689   }
4690 
4691   size_t total_used() {
4692     return _total_used;
4693   }
4694 };
4695 
4696 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4697   assert_at_safepoint_on_vm_thread();
4698 
4699   if (!free_list_only) {
4700     _eden.clear();
4701     _survivor.clear();
4702   }
4703 
4704   RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4705   heap_region_iterate(&cl);
4706 
4707   if (!free_list_only) {
4708     set_used(cl.total_used());
4709     if (_archive_allocator != NULL) {
4710       _archive_allocator->clear_used();
4711     }
4712   }
4713   assert_used_and_recalculate_used_equal(this);
4714 }
4715 
4716 // Methods for the mutator alloc region
4717 
4718 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4719                                                       bool force,
4720                                                       uint node_index) {
4721   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4722   bool should_allocate = policy()->should_allocate_mutator_region();
4723   if (force || should_allocate) {
4724     HeapRegion* new_alloc_region = new_region(word_size,
4725                                               HeapRegionType::Eden,
4726                                               false /* do_expand */,
4727                                               node_index);
4728     if (new_alloc_region != NULL) {
4729       set_region_short_lived_locked(new_alloc_region);
4730       _hr_printer.alloc(new_alloc_region, !should_allocate);
4731       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4732       _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4733       return new_alloc_region;
4734     }
4735   }
4736   return NULL;
4737 }
4738 
4739 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4740                                                   size_t allocated_bytes) {
4741   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4742   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4743 
4744   collection_set()->add_eden_region(alloc_region);
4745   increase_used(allocated_bytes);
4746   _eden.add_used_bytes(allocated_bytes);
4747   _hr_printer.retire(alloc_region);
4748 
4749   // We update the eden sizes here, when the region is retired,
4750   // instead of when it's allocated, since this is the point that its
4751   // used space has been recorded in _summary_bytes_used.
4752   g1mm()->update_eden_size();
4753 }
4754 
4755 // Methods for the GC alloc regions
4756 
4757 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4758   if (dest.is_old()) {
4759     return true;
4760   } else {
4761     return survivor_regions_count() < policy()->max_survivor_regions();
4762   }
4763 }
4764 
4765 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4766   assert(FreeList_lock->owned_by_self(), "pre-condition");
4767 
4768   if (!has_more_regions(dest)) {
4769     return NULL;
4770   }
4771 
4772   HeapRegionType type;
4773   if (dest.is_young()) {
4774     type = HeapRegionType::Survivor;
4775   } else {
4776     type = HeapRegionType::Old;
4777   }
4778 
4779   HeapRegion* new_alloc_region = new_region(word_size,
4780                                             type,
4781                                             true /* do_expand */,
4782                                             node_index);
4783 
4784   if (new_alloc_region != NULL) {
4785     if (type.is_survivor()) {
4786       new_alloc_region->set_survivor();
4787       _survivor.add(new_alloc_region);
4788       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4789     } else {
4790       new_alloc_region->set_old();
4791       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4792     }
4793     _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4794     register_region_with_region_attr(new_alloc_region);
4795     _hr_printer.alloc(new_alloc_region);
4796     return new_alloc_region;
4797   }
4798   return NULL;
4799 }
4800 
4801 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4802                                              size_t allocated_bytes,
4803                                              G1HeapRegionAttr dest) {
4804   _bytes_used_during_gc += allocated_bytes;
4805   if (dest.is_old()) {
4806     old_set_add(alloc_region);
4807   } else {
4808     assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4809     _survivor.add_used_bytes(allocated_bytes);
4810   }
4811 
4812   bool const during_im = collector_state()->in_concurrent_start_gc();
4813   if (during_im && allocated_bytes > 0) {
4814     _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4815   }
4816   _hr_printer.retire(alloc_region);
4817 }
4818 
4819 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4820   bool expanded = false;
4821   uint index = _hrm->find_highest_free(&expanded);
4822 
4823   if (index != G1_NO_HRM_INDEX) {
4824     if (expanded) {
4825       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4826                                 HeapRegion::GrainWords * HeapWordSize);
4827     }
4828     return _hrm->allocate_free_regions_starting_at(index, 1);
4829   }
4830   return NULL;
4831 }
4832 
4833 // Optimized nmethod scanning
4834 
4835 class RegisterNMethodOopClosure: public OopClosure {
4836   G1CollectedHeap* _g1h;
4837   nmethod* _nm;
4838 
4839   template <class T> void do_oop_work(T* p) {
4840     T heap_oop = RawAccess<>::oop_load(p);
4841     if (!CompressedOops::is_null(heap_oop)) {
4842       oop obj = CompressedOops::decode_not_null(heap_oop);
4843       HeapRegion* hr = _g1h->heap_region_containing(obj);
4844       assert(!hr->is_continues_humongous(),
4845              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4846              " starting at " HR_FORMAT,
4847              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4848 
4849       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4850       hr->add_strong_code_root_locked(_nm);
4851     }
4852   }
4853 
4854 public:
4855   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4856     _g1h(g1h), _nm(nm) {}
4857 
4858   void do_oop(oop* p)       { do_oop_work(p); }
4859   void do_oop(narrowOop* p) { do_oop_work(p); }
4860 };
4861 
4862 class UnregisterNMethodOopClosure: public OopClosure {
4863   G1CollectedHeap* _g1h;
4864   nmethod* _nm;
4865 
4866   template <class T> void do_oop_work(T* p) {
4867     T heap_oop = RawAccess<>::oop_load(p);
4868     if (!CompressedOops::is_null(heap_oop)) {
4869       oop obj = CompressedOops::decode_not_null(heap_oop);
4870       HeapRegion* hr = _g1h->heap_region_containing(obj);
4871       assert(!hr->is_continues_humongous(),
4872              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4873              " starting at " HR_FORMAT,
4874              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4875 
4876       hr->remove_strong_code_root(_nm);
4877     }
4878   }
4879 
4880 public:
4881   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4882     _g1h(g1h), _nm(nm) {}
4883 
4884   void do_oop(oop* p)       { do_oop_work(p); }
4885   void do_oop(narrowOop* p) { do_oop_work(p); }
4886 };
4887 
4888 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4889   guarantee(nm != NULL, "sanity");
4890   RegisterNMethodOopClosure reg_cl(this, nm);
4891   nm->oops_do(&reg_cl);
4892 }
4893 
4894 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4895   guarantee(nm != NULL, "sanity");
4896   UnregisterNMethodOopClosure reg_cl(this, nm);
4897   nm->oops_do(&reg_cl, true);
4898 }
4899 
4900 void G1CollectedHeap::purge_code_root_memory() {
4901   double purge_start = os::elapsedTime();
4902   G1CodeRootSet::purge();
4903   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4904   phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4905 }
4906 
4907 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4908   G1CollectedHeap* _g1h;
4909 
4910 public:
4911   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4912     _g1h(g1h) {}
4913 
4914   void do_code_blob(CodeBlob* cb) {
4915     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4916     if (nm == NULL) {
4917       return;
4918     }
4919 
4920     _g1h->register_nmethod(nm);
4921   }
4922 };
4923 
4924 void G1CollectedHeap::rebuild_strong_code_roots() {
4925   RebuildStrongCodeRootClosure blob_cl(this);
4926   CodeCache::blobs_do(&blob_cl);
4927 }
4928 
4929 void G1CollectedHeap::initialize_serviceability() {
4930   _g1mm->initialize_serviceability();
4931 }
4932 
4933 MemoryUsage G1CollectedHeap::memory_usage() {
4934   return _g1mm->memory_usage();
4935 }
4936 
4937 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4938   return _g1mm->memory_managers();
4939 }
4940 
4941 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4942   return _g1mm->memory_pools();
4943 }
--- EOF ---