1 /*
   2  * Copyright (c) 2001, 2023, 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 "compiler/oopMap.hpp"
  32 #include "gc/g1/g1Allocator.inline.hpp"
  33 #include "gc/g1/g1Arguments.hpp"
  34 #include "gc/g1/g1BarrierSet.hpp"
  35 #include "gc/g1/g1BatchedTask.hpp"
  36 #include "gc/g1/g1CollectedHeap.inline.hpp"
  37 #include "gc/g1/g1CollectionSet.hpp"
  38 #include "gc/g1/g1CollectionSetCandidates.hpp"
  39 #include "gc/g1/g1CollectorState.hpp"
  40 #include "gc/g1/g1ConcurrentRefine.hpp"
  41 #include "gc/g1/g1ConcurrentRefineThread.hpp"
  42 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
  43 #include "gc/g1/g1DirtyCardQueue.hpp"
  44 #include "gc/g1/g1EvacStats.inline.hpp"
  45 #include "gc/g1/g1FullCollector.hpp"
  46 #include "gc/g1/g1GCCounters.hpp"
  47 #include "gc/g1/g1GCParPhaseTimesTracker.hpp"
  48 #include "gc/g1/g1GCPhaseTimes.hpp"
  49 #include "gc/g1/g1GCPauseType.hpp"
  50 #include "gc/g1/g1HeapSizingPolicy.hpp"
  51 #include "gc/g1/g1HeapTransition.hpp"
  52 #include "gc/g1/g1HeapVerifier.hpp"
  53 #include "gc/g1/g1InitLogger.hpp"
  54 #include "gc/g1/g1MemoryPool.hpp"
  55 #include "gc/g1/g1MonotonicArenaFreeMemoryTask.hpp"
  56 #include "gc/g1/g1OopClosures.inline.hpp"
  57 #include "gc/g1/g1ParallelCleaning.hpp"
  58 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  59 #include "gc/g1/g1PeriodicGCTask.hpp"
  60 #include "gc/g1/g1Policy.hpp"
  61 #include "gc/g1/g1RedirtyCardsQueue.hpp"
  62 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  63 #include "gc/g1/g1RemSet.hpp"
  64 #include "gc/g1/g1RootClosures.hpp"
  65 #include "gc/g1/g1RootProcessor.hpp"
  66 #include "gc/g1/g1SATBMarkQueueSet.hpp"
  67 #include "gc/g1/g1ServiceThread.hpp"
  68 #include "gc/g1/g1ThreadLocalData.hpp"
  69 #include "gc/g1/g1Trace.hpp"
  70 #include "gc/g1/g1UncommitRegionTask.hpp"
  71 #include "gc/g1/g1VMOperations.hpp"
  72 #include "gc/g1/g1YoungCollector.hpp"
  73 #include "gc/g1/g1YoungGCEvacFailureInjector.hpp"
  74 #include "gc/g1/heapRegion.inline.hpp"
  75 #include "gc/g1/heapRegionRemSet.inline.hpp"
  76 #include "gc/g1/heapRegionSet.inline.hpp"
  77 #include "gc/shared/concurrentGCBreakpoints.hpp"
  78 #include "gc/shared/gcBehaviours.hpp"
  79 #include "gc/shared/gcHeapSummary.hpp"
  80 #include "gc/shared/gcId.hpp"
  81 #include "gc/shared/gcLocker.inline.hpp"
  82 #include "gc/shared/gcTimer.hpp"
  83 #include "gc/shared/gcTraceTime.inline.hpp"
  84 #include "gc/shared/generationSpec.hpp"
  85 #include "gc/shared/isGCActiveMark.hpp"
  86 #include "gc/shared/locationPrinter.inline.hpp"
  87 #include "gc/shared/oopStorageParState.hpp"
  88 #include "gc/shared/preservedMarks.inline.hpp"
  89 #include "gc/shared/slidingForwarding.inline.hpp"
  90 #include "gc/shared/suspendibleThreadSet.hpp"
  91 #include "gc/shared/referenceProcessor.inline.hpp"
  92 #include "gc/shared/suspendibleThreadSet.hpp"
  93 #include "gc/shared/taskqueue.inline.hpp"
  94 #include "gc/shared/taskTerminator.hpp"
  95 #include "gc/shared/tlab_globals.hpp"
  96 #include "gc/shared/workerPolicy.hpp"
  97 #include "gc/shared/weakProcessor.inline.hpp"
  98 #include "logging/log.hpp"
  99 #include "memory/allocation.hpp"
 100 #include "memory/heapInspection.hpp"
 101 #include "memory/iterator.hpp"
 102 #include "memory/metaspaceUtils.hpp"
 103 #include "memory/resourceArea.hpp"
 104 #include "memory/universe.hpp"
 105 #include "oops/access.inline.hpp"
 106 #include "oops/compressedOops.inline.hpp"
 107 #include "oops/oop.inline.hpp"
 108 #include "runtime/atomic.hpp"
 109 #include "runtime/handles.inline.hpp"
 110 #include "runtime/init.hpp"
 111 #include "runtime/java.hpp"
 112 #include "runtime/orderAccess.hpp"
 113 #include "runtime/threadSMR.hpp"
 114 #include "runtime/vmThread.hpp"
 115 #include "utilities/align.hpp"
 116 #include "utilities/autoRestore.hpp"
 117 #include "utilities/bitMap.inline.hpp"
 118 #include "utilities/globalDefinitions.hpp"
 119 #include "utilities/stack.inline.hpp"
 120 
 121 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
 122 
 123 // INVARIANTS/NOTES
 124 //
 125 // All allocation activity covered by the G1CollectedHeap interface is
 126 // serialized by acquiring the HeapLock.  This happens in mem_allocate
 127 // and allocate_new_tlab, which are the "entry" points to the
 128 // allocation code from the rest of the JVM.  (Note that this does not
 129 // apply to TLAB allocation, which is not part of this interface: it
 130 // is done by clients of this interface.)
 131 
 132 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 133   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 134 }
 135 
 136 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 137   // The from card cache is not the memory that is actually committed. So we cannot
 138   // take advantage of the zero_filled parameter.
 139   reset_from_card_cache(start_idx, num_regions);
 140 }
 141 
 142 void G1CollectedHeap::run_batch_task(G1BatchedTask* cl) {
 143   uint num_workers = MAX2(1u, MIN2(cl->num_workers_estimate(), workers()->active_workers()));
 144   cl->set_max_workers(num_workers);
 145   workers()->run_task(cl, num_workers);
 146 }
 147 
 148 uint G1CollectedHeap::get_chunks_per_region() {
 149   uint log_region_size = HeapRegion::LogOfHRGrainBytes;
 150   // Limit the expected input values to current known possible values of the
 151   // (log) region size. Adjust as necessary after testing if changing the permissible
 152   // values for region size.
 153   assert(log_region_size >= 20 && log_region_size <= 29,
 154          "expected value in [20,29], but got %u", log_region_size);
 155   return 1u << (log_region_size / 2 - 4);
 156 }
 157 
 158 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 159                                              MemRegion mr) {
 160   return new HeapRegion(hrs_index, bot(), mr, &_card_set_config);
 161 }
 162 
 163 // Private methods.
 164 
 165 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
 166                                         HeapRegionType type,
 167                                         bool do_expand,
 168                                         uint node_index) {
 169   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 170          "the only time we use this to allocate a humongous region is "
 171          "when we are allocating a single humongous region");
 172 
 173   HeapRegion* res = _hrm.allocate_free_region(type, node_index);
 174 
 175   if (res == NULL && do_expand) {
 176     // Currently, only attempts to allocate GC alloc regions set
 177     // do_expand to true. So, we should only reach here during a
 178     // safepoint.
 179     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 180 
 181     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 182                               word_size * HeapWordSize);
 183 
 184     assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
 185            "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
 186            word_size * HeapWordSize);
 187     if (expand_single_region(node_index)) {
 188       // Given that expand_single_region() succeeded in expanding the heap, and we
 189       // always expand the heap by an amount aligned to the heap
 190       // region size, the free list should in theory not be empty.
 191       // In either case allocate_free_region() will check for NULL.
 192       res = _hrm.allocate_free_region(type, node_index);
 193     }
 194   }
 195   return res;
 196 }
 197 
 198 HeapWord*
 199 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
 200                                                            uint num_regions,
 201                                                            size_t word_size) {
 202   assert(first_hr != NULL, "pre-condition");
 203   assert(is_humongous(word_size), "word_size should be humongous");
 204   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 205 
 206   // Index of last region in the series.
 207   uint first = first_hr->hrm_index();
 208   uint last = first + num_regions - 1;
 209 
 210   // We need to initialize the region(s) we just discovered. This is
 211   // a bit tricky given that it can happen concurrently with
 212   // refinement threads refining cards on these regions and
 213   // potentially wanting to refine the BOT as they are scanning
 214   // those cards (this can happen shortly after a cleanup; see CR
 215   // 6991377). So we have to set up the region(s) carefully and in
 216   // a specific order.
 217 
 218   // The word size sum of all the regions we will allocate.
 219   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 220   assert(word_size <= word_size_sum, "sanity");
 221 
 222   // The passed in hr will be the "starts humongous" region. The header
 223   // of the new object will be placed at the bottom of this region.
 224   HeapWord* new_obj = first_hr->bottom();
 225   // This will be the new top of the new object.
 226   HeapWord* obj_top = new_obj + word_size;
 227 
 228   // First, we need to zero the header of the space that we will be
 229   // allocating. When we update top further down, some refinement
 230   // threads might try to scan the region. By zeroing the header we
 231   // ensure that any thread that will try to scan the region will
 232   // come across the zero klass word and bail out.
 233   //
 234   // NOTE: It would not have been correct to have used
 235   // CollectedHeap::fill_with_object() and make the space look like
 236   // an int array. The thread that is doing the allocation will
 237   // later update the object header to a potentially different array
 238   // type and, for a very short period of time, the klass and length
 239   // fields will be inconsistent. This could cause a refinement
 240   // thread to calculate the object size incorrectly.
 241   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 242 
 243   // Next, pad out the unused tail of the last region with filler
 244   // objects, for improved usage accounting.
 245   // How many words we use for filler objects.
 246   size_t word_fill_size = word_size_sum - word_size;
 247 
 248   // How many words memory we "waste" which cannot hold a filler object.
 249   size_t words_not_fillable = 0;
 250 
 251   if (word_fill_size >= min_fill_size()) {
 252     fill_with_objects(obj_top, word_fill_size);
 253   } else if (word_fill_size > 0) {
 254     // We have space to fill, but we cannot fit an object there.
 255     words_not_fillable = word_fill_size;
 256     word_fill_size = 0;
 257   }
 258 
 259   // We will set up the first region as "starts humongous". This
 260   // will also update the BOT covering all the regions to reflect
 261   // that there is a single object that starts at the bottom of the
 262   // first region.
 263   first_hr->set_starts_humongous(obj_top, word_fill_size);
 264   _policy->remset_tracker()->update_at_allocate(first_hr);
 265   // Then, if there are any, we will set up the "continues
 266   // humongous" regions.
 267   HeapRegion* hr = NULL;
 268   for (uint i = first + 1; i <= last; ++i) {
 269     hr = region_at(i);
 270     hr->set_continues_humongous(first_hr);
 271     _policy->remset_tracker()->update_at_allocate(hr);
 272   }
 273 
 274   // Up to this point no concurrent thread would have been able to
 275   // do any scanning on any region in this series. All the top
 276   // fields still point to bottom, so the intersection between
 277   // [bottom,top] and [card_start,card_end] will be empty. Before we
 278   // update the top fields, we'll do a storestore to make sure that
 279   // no thread sees the update to top before the zeroing of the
 280   // object header and the BOT initialization.
 281   OrderAccess::storestore();
 282 
 283   // Now, we will update the top fields of the "continues humongous"
 284   // regions except the last one.
 285   for (uint i = first; i < last; ++i) {
 286     hr = region_at(i);
 287     hr->set_top(hr->end());
 288   }
 289 
 290   hr = region_at(last);
 291   // If we cannot fit a filler object, we must set top to the end
 292   // of the humongous object, otherwise we cannot iterate the heap
 293   // and the BOT will not be complete.
 294   hr->set_top(hr->end() - words_not_fillable);
 295 
 296   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 297          "obj_top should be in last region");
 298 
 299   assert(words_not_fillable == 0 ||
 300          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 301          "Miscalculation in humongous allocation");
 302 
 303   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 304 
 305   for (uint i = first; i <= last; ++i) {
 306     hr = region_at(i);
 307     _humongous_set.add(hr);
 308     _hr_printer.alloc(hr);
 309   }
 310 
 311   return new_obj;
 312 }
 313 
 314 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 315   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 316   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 317 }
 318 
 319 // If could fit into free regions w/o expansion, try.
 320 // Otherwise, if can expand, do so.
 321 // Otherwise, if using ex regions might help, try with ex given back.
 322 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 323   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 324 
 325   _verifier->verify_region_sets_optional();
 326 
 327   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 328 
 329   // Policy: First try to allocate a humongous object in the free list.
 330   HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions);
 331   if (humongous_start == NULL) {
 332     // Policy: We could not find enough regions for the humongous object in the
 333     // free list. Look through the heap to find a mix of free and uncommitted regions.
 334     // If so, expand the heap and allocate the humongous object.
 335     humongous_start = _hrm.expand_and_allocate_humongous(obj_regions);
 336     if (humongous_start != NULL) {
 337       // We managed to find a region by expanding the heap.
 338       log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
 339                                 word_size * HeapWordSize);
 340       policy()->record_new_heap_size(num_regions());
 341     } else {
 342       // Policy: Potentially trigger a defragmentation GC.
 343     }
 344   }
 345 
 346   HeapWord* result = NULL;
 347   if (humongous_start != NULL) {
 348     result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
 349     assert(result != NULL, "it should always return a valid result");
 350 
 351     // A successful humongous object allocation changes the used space
 352     // information of the old generation so we need to recalculate the
 353     // sizes and update the jstat counters here.
 354     monitoring_support()->update_sizes();
 355   }
 356 
 357   _verifier->verify_region_sets_optional();
 358 
 359   return result;
 360 }
 361 
 362 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
 363                                              size_t requested_size,
 364                                              size_t* actual_size) {
 365   assert_heap_not_locked_and_not_at_safepoint();
 366   assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
 367 
 368   return attempt_allocation(min_size, requested_size, actual_size);
 369 }
 370 
 371 HeapWord*
 372 G1CollectedHeap::mem_allocate(size_t word_size,
 373                               bool*  gc_overhead_limit_was_exceeded) {
 374   assert_heap_not_locked_and_not_at_safepoint();
 375 
 376   if (is_humongous(word_size)) {
 377     return attempt_allocation_humongous(word_size);
 378   }
 379   size_t dummy = 0;
 380   return attempt_allocation(word_size, word_size, &dummy);
 381 }
 382 
 383 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 384   ResourceMark rm; // For retrieving the thread names in log messages.
 385 
 386   // Make sure you read the note in attempt_allocation_humongous().
 387 
 388   assert_heap_not_locked_and_not_at_safepoint();
 389   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 390          "be called for humongous allocation requests");
 391 
 392   // We should only get here after the first-level allocation attempt
 393   // (attempt_allocation()) failed to allocate.
 394 
 395   // We will loop until a) we manage to successfully perform the
 396   // allocation or b) we successfully schedule a collection which
 397   // fails to perform the allocation. b) is the only case when we'll
 398   // return NULL.
 399   HeapWord* result = NULL;
 400   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 401     bool should_try_gc;
 402     uint gc_count_before;
 403 
 404     {
 405       MutexLocker x(Heap_lock);
 406 
 407       // Now that we have the lock, we first retry the allocation in case another
 408       // thread changed the region while we were waiting to acquire the lock.
 409       result = _allocator->attempt_allocation_locked(word_size);
 410       if (result != NULL) {
 411         return result;
 412       }
 413 
 414       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 415       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 416       // waiting because the GCLocker is active to not wait too long.
 417       if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
 418         // No need for an ergo message here, can_expand_young_list() does this when
 419         // it returns true.
 420         result = _allocator->attempt_allocation_force(word_size);
 421         if (result != NULL) {
 422           return result;
 423         }
 424       }
 425 
 426       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 427       // the GCLocker initiated GC has been performed and then retry. This includes
 428       // the case when the GC Locker is not active but has not been performed.
 429       should_try_gc = !GCLocker::needs_gc();
 430       // Read the GC count while still holding the Heap_lock.
 431       gc_count_before = total_collections();
 432     }
 433 
 434     if (should_try_gc) {
 435       bool succeeded;
 436       result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_inc_collection_pause);
 437       if (result != NULL) {
 438         assert(succeeded, "only way to get back a non-NULL result");
 439         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 440                              Thread::current()->name(), p2i(result));
 441         return result;
 442       }
 443 
 444       if (succeeded) {
 445         // We successfully scheduled a collection which failed to allocate. No
 446         // point in trying to allocate further. We'll just return NULL.
 447         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 448                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 449         return NULL;
 450       }
 451       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 452                            Thread::current()->name(), word_size);
 453     } else {
 454       // Failed to schedule a collection.
 455       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 456         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 457                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 458         return NULL;
 459       }
 460       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 461       // The GCLocker is either active or the GCLocker initiated
 462       // GC has not yet been performed. Stall until it is and
 463       // then retry the allocation.
 464       GCLocker::stall_until_clear();
 465       gclocker_retry_count += 1;
 466     }
 467 
 468     // We can reach here if we were unsuccessful in scheduling a
 469     // collection (because another thread beat us to it) or if we were
 470     // stalled due to the GC locker. In either can we should retry the
 471     // allocation attempt in case another thread successfully
 472     // performed a collection and reclaimed enough space. We do the
 473     // first attempt (without holding the Heap_lock) here and the
 474     // follow-on attempt will be at the start of the next loop
 475     // iteration (after taking the Heap_lock).
 476     size_t dummy = 0;
 477     result = _allocator->attempt_allocation(word_size, word_size, &dummy);
 478     if (result != NULL) {
 479       return result;
 480     }
 481 
 482     // Give a warning if we seem to be looping forever.
 483     if ((QueuedAllocationWarningCount > 0) &&
 484         (try_count % QueuedAllocationWarningCount == 0)) {
 485       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 486                              Thread::current()->name(), try_count, word_size);
 487     }
 488   }
 489 
 490   ShouldNotReachHere();
 491   return NULL;
 492 }
 493 
 494 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 495   assert(ranges != NULL, "MemRegion array NULL");
 496   assert(count != 0, "No MemRegions provided");
 497   MemRegion reserved = _hrm.reserved();
 498   for (size_t i = 0; i < count; i++) {
 499     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 500       return false;
 501     }
 502   }
 503   return true;
 504 }
 505 
 506 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 507                                             size_t count,
 508                                             bool open) {
 509   assert(!is_init_completed(), "Expect to be called at JVM init time");
 510   assert(ranges != NULL, "MemRegion array NULL");
 511   assert(count != 0, "No MemRegions provided");
 512   MutexLocker x(Heap_lock);
 513 
 514   MemRegion reserved = _hrm.reserved();
 515   HeapWord* prev_last_addr = NULL;
 516   HeapRegion* prev_last_region = NULL;
 517 
 518   // Temporarily disable pretouching of heap pages. This interface is used
 519   // when mmap'ing archived heap data in, so pre-touching is wasted.
 520   FlagSetting fs(AlwaysPreTouch, false);
 521 
 522   // For each specified MemRegion range, allocate the corresponding G1
 523   // regions and mark them as archive regions. We expect the ranges
 524   // in ascending starting address order, without overlap.
 525   for (size_t i = 0; i < count; i++) {
 526     MemRegion curr_range = ranges[i];
 527     HeapWord* start_address = curr_range.start();
 528     size_t word_size = curr_range.word_size();
 529     HeapWord* last_address = curr_range.last();
 530     size_t commits = 0;
 531 
 532     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 533               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 534               p2i(start_address), p2i(last_address));
 535     guarantee(start_address > prev_last_addr,
 536               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 537               p2i(start_address), p2i(prev_last_addr));
 538     prev_last_addr = last_address;
 539 
 540     // Check for ranges that start in the same G1 region in which the previous
 541     // range ended, and adjust the start address so we don't try to allocate
 542     // the same region again. If the current range is entirely within that
 543     // region, skip it, just adjusting the recorded top.
 544     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 545     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 546       start_address = start_region->end();
 547       if (start_address > last_address) {
 548         increase_used(word_size * HeapWordSize);
 549         start_region->set_top(last_address + 1);
 550         continue;
 551       }
 552       start_region->set_top(start_address);
 553       curr_range = MemRegion(start_address, last_address + 1);
 554       start_region = _hrm.addr_to_region(start_address);
 555     }
 556 
 557     // Perform the actual region allocation, exiting if it fails.
 558     // Then note how much new space we have allocated.
 559     if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
 560       return false;
 561     }
 562     increase_used(word_size * HeapWordSize);
 563     if (commits != 0) {
 564       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 565                                 HeapRegion::GrainWords * HeapWordSize * commits);
 566 
 567     }
 568 
 569     // Mark each G1 region touched by the range as archive, add it to
 570     // the old set, and set top.
 571     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 572     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 573     prev_last_region = last_region;
 574 
 575     while (curr_region != NULL) {
 576       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 577              "Region already in use (index %u)", curr_region->hrm_index());
 578       if (open) {
 579         curr_region->set_open_archive();
 580       } else {
 581         curr_region->set_closed_archive();
 582       }
 583       _hr_printer.alloc(curr_region);
 584       _archive_set.add(curr_region);
 585       HeapWord* top;
 586       HeapRegion* next_region;
 587       if (curr_region != last_region) {
 588         top = curr_region->end();
 589         next_region = _hrm.next_region_in_heap(curr_region);
 590       } else {
 591         top = last_address + 1;
 592         next_region = NULL;
 593       }
 594       curr_region->set_top(top);
 595       curr_region = next_region;
 596     }
 597   }
 598   return true;
 599 }
 600 
 601 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 602   assert(!is_init_completed(), "Expect to be called at JVM init time");
 603   assert(ranges != NULL, "MemRegion array NULL");
 604   assert(count != 0, "No MemRegions provided");
 605   MemRegion reserved = _hrm.reserved();
 606   HeapWord *prev_last_addr = NULL;
 607   HeapRegion* prev_last_region = NULL;
 608 
 609   // For each MemRegion, create filler objects, if needed, in the G1 regions
 610   // that contain the address range. The address range actually within the
 611   // MemRegion will not be modified. That is assumed to have been initialized
 612   // elsewhere, probably via an mmap of archived heap data.
 613   MutexLocker x(Heap_lock);
 614   for (size_t i = 0; i < count; i++) {
 615     HeapWord* start_address = ranges[i].start();
 616     HeapWord* last_address = ranges[i].last();
 617 
 618     assert(reserved.contains(start_address) && reserved.contains(last_address),
 619            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 620            p2i(start_address), p2i(last_address));
 621     assert(start_address > prev_last_addr,
 622            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 623            p2i(start_address), p2i(prev_last_addr));
 624 
 625     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 626     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 627     HeapWord* bottom_address = start_region->bottom();
 628 
 629     // Check for a range beginning in the same region in which the
 630     // previous one ended.
 631     if (start_region == prev_last_region) {
 632       bottom_address = prev_last_addr + 1;
 633     }
 634 
 635     // Verify that the regions were all marked as archive regions by
 636     // alloc_archive_regions.
 637     HeapRegion* curr_region = start_region;
 638     while (curr_region != NULL) {
 639       guarantee(curr_region->is_archive(),
 640                 "Expected archive region at index %u", curr_region->hrm_index());
 641       if (curr_region != last_region) {
 642         curr_region = _hrm.next_region_in_heap(curr_region);
 643       } else {
 644         curr_region = NULL;
 645       }
 646     }
 647 
 648     prev_last_addr = last_address;
 649     prev_last_region = last_region;
 650 
 651     // Fill the memory below the allocated range with dummy object(s),
 652     // if the region bottom does not match the range start, or if the previous
 653     // range ended within the same G1 region, and there is a gap.
 654     assert(start_address >= bottom_address, "bottom address should not be greater than start address");
 655     if (start_address > bottom_address) {
 656       size_t fill_size = pointer_delta(start_address, bottom_address);
 657       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 658       increase_used(fill_size * HeapWordSize);
 659     }
 660   }
 661 }
 662 
 663 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
 664                                                      size_t desired_word_size,
 665                                                      size_t* actual_word_size) {
 666   assert_heap_not_locked_and_not_at_safepoint();
 667   assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
 668          "be called for humongous allocation requests");
 669 
 670   HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
 671 
 672   if (result == NULL) {
 673     *actual_word_size = desired_word_size;
 674     result = attempt_allocation_slow(desired_word_size);
 675   }
 676 
 677   assert_heap_not_locked();
 678   if (result != NULL) {
 679     assert(*actual_word_size != 0, "Actual size must have been set here");
 680     dirty_young_block(result, *actual_word_size);
 681   } else {
 682     *actual_word_size = 0;
 683   }
 684 
 685   return result;
 686 }
 687 
 688 void G1CollectedHeap::populate_archive_regions_bot_part(MemRegion* ranges, size_t count) {
 689   assert(!is_init_completed(), "Expect to be called at JVM init time");
 690   assert(ranges != NULL, "MemRegion array NULL");
 691   assert(count != 0, "No MemRegions provided");
 692 
 693   HeapWord* st = ranges[0].start();
 694   HeapWord* last = ranges[count-1].last();
 695   HeapRegion* hr_st = _hrm.addr_to_region(st);
 696   HeapRegion* hr_last = _hrm.addr_to_region(last);
 697 
 698   HeapRegion* hr_curr = hr_st;
 699   while (hr_curr != NULL) {
 700     hr_curr->update_bot();
 701     if (hr_curr != hr_last) {
 702       hr_curr = _hrm.next_region_in_heap(hr_curr);
 703     } else {
 704       hr_curr = NULL;
 705     }
 706   }
 707 }
 708 
 709 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 710   assert(!is_init_completed(), "Expect to be called at JVM init time");
 711   assert(ranges != NULL, "MemRegion array NULL");
 712   assert(count != 0, "No MemRegions provided");
 713   MemRegion reserved = _hrm.reserved();
 714   HeapWord* prev_last_addr = NULL;
 715   HeapRegion* prev_last_region = NULL;
 716   size_t size_used = 0;
 717   uint shrink_count = 0;
 718 
 719   // For each Memregion, free the G1 regions that constitute it, and
 720   // notify mark-sweep that the range is no longer to be considered 'archive.'
 721   MutexLocker x(Heap_lock);
 722   for (size_t i = 0; i < count; i++) {
 723     HeapWord* start_address = ranges[i].start();
 724     HeapWord* last_address = ranges[i].last();
 725 
 726     assert(reserved.contains(start_address) && reserved.contains(last_address),
 727            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 728            p2i(start_address), p2i(last_address));
 729     assert(start_address > prev_last_addr,
 730            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 731            p2i(start_address), p2i(prev_last_addr));
 732     size_used += ranges[i].byte_size();
 733     prev_last_addr = last_address;
 734 
 735     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 736     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 737 
 738     // Check for ranges that start in the same G1 region in which the previous
 739     // range ended, and adjust the start address so we don't try to free
 740     // the same region again. If the current range is entirely within that
 741     // region, skip it.
 742     if (start_region == prev_last_region) {
 743       start_address = start_region->end();
 744       if (start_address > last_address) {
 745         continue;
 746       }
 747       start_region = _hrm.addr_to_region(start_address);
 748     }
 749     prev_last_region = last_region;
 750 
 751     // After verifying that each region was marked as an archive region by
 752     // alloc_archive_regions, set it free and empty and uncommit it.
 753     HeapRegion* curr_region = start_region;
 754     while (curr_region != NULL) {
 755       guarantee(curr_region->is_archive(),
 756                 "Expected archive region at index %u", curr_region->hrm_index());
 757       uint curr_index = curr_region->hrm_index();
 758       _archive_set.remove(curr_region);
 759       curr_region->set_free();
 760       curr_region->set_top(curr_region->bottom());
 761       if (curr_region != last_region) {
 762         curr_region = _hrm.next_region_in_heap(curr_region);
 763       } else {
 764         curr_region = NULL;
 765       }
 766 
 767       _hrm.shrink_at(curr_index, 1);
 768       shrink_count++;
 769     }
 770   }
 771 
 772   if (shrink_count != 0) {
 773     log_debug(gc, ergo, heap)("Attempt heap shrinking (archive regions). Total size: " SIZE_FORMAT "B",
 774                               HeapRegion::GrainWords * HeapWordSize * shrink_count);
 775     // Explicit uncommit.
 776     uncommit_regions(shrink_count);
 777   }
 778   decrease_used(size_used);
 779 }
 780 
 781 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 782   ResourceMark rm; // For retrieving the thread names in log messages.
 783 
 784   // The structure of this method has a lot of similarities to
 785   // attempt_allocation_slow(). The reason these two were not merged
 786   // into a single one is that such a method would require several "if
 787   // allocation is not humongous do this, otherwise do that"
 788   // conditional paths which would obscure its flow. In fact, an early
 789   // version of this code did use a unified method which was harder to
 790   // follow and, as a result, it had subtle bugs that were hard to
 791   // track down. So keeping these two methods separate allows each to
 792   // be more readable. It will be good to keep these two in sync as
 793   // much as possible.
 794 
 795   assert_heap_not_locked_and_not_at_safepoint();
 796   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 797          "should only be called for humongous allocations");
 798 
 799   // Humongous objects can exhaust the heap quickly, so we should check if we
 800   // need to start a marking cycle at each humongous object allocation. We do
 801   // the check before we do the actual allocation. The reason for doing it
 802   // before the allocation is that we avoid having to keep track of the newly
 803   // allocated memory while we do a GC.
 804   if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
 805                                         word_size)) {
 806     collect(GCCause::_g1_humongous_allocation);
 807   }
 808 
 809   // We will loop until a) we manage to successfully perform the
 810   // allocation or b) we successfully schedule a collection which
 811   // fails to perform the allocation. b) is the only case when we'll
 812   // return NULL.
 813   HeapWord* result = NULL;
 814   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 815     bool should_try_gc;
 816     uint gc_count_before;
 817 
 818 
 819     {
 820       MutexLocker x(Heap_lock);
 821 
 822       size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 823       // Given that humongous objects are not allocated in young
 824       // regions, we'll first try to do the allocation without doing a
 825       // collection hoping that there's enough space in the heap.
 826       result = humongous_obj_allocate(word_size);
 827       if (result != NULL) {
 828         policy()->old_gen_alloc_tracker()->
 829           add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 830         return result;
 831       }
 832 
 833       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 834       // the GCLocker initiated GC has been performed and then retry. This includes
 835       // the case when the GC Locker is not active but has not been performed.
 836       should_try_gc = !GCLocker::needs_gc();
 837       // Read the GC count while still holding the Heap_lock.
 838       gc_count_before = total_collections();
 839     }
 840 
 841     if (should_try_gc) {
 842       bool succeeded;
 843       result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_humongous_allocation);
 844       if (result != NULL) {
 845         assert(succeeded, "only way to get back a non-NULL result");
 846         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 847                              Thread::current()->name(), p2i(result));
 848         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 849         policy()->old_gen_alloc_tracker()->
 850           record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
 851         return result;
 852       }
 853 
 854       if (succeeded) {
 855         // We successfully scheduled a collection which failed to allocate. No
 856         // point in trying to allocate further. We'll just return NULL.
 857         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 858                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 859         return NULL;
 860       }
 861       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 862                            Thread::current()->name(), word_size);
 863     } else {
 864       // Failed to schedule a collection.
 865       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 866         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 867                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 868         return NULL;
 869       }
 870       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 871       // The GCLocker is either active or the GCLocker initiated
 872       // GC has not yet been performed. Stall until it is and
 873       // then retry the allocation.
 874       GCLocker::stall_until_clear();
 875       gclocker_retry_count += 1;
 876     }
 877 
 878 
 879     // We can reach here if we were unsuccessful in scheduling a
 880     // collection (because another thread beat us to it) or if we were
 881     // stalled due to the GC locker. In either can we should retry the
 882     // allocation attempt in case another thread successfully
 883     // performed a collection and reclaimed enough space.
 884     // Humongous object allocation always needs a lock, so we wait for the retry
 885     // in the next iteration of the loop, unlike for the regular iteration case.
 886     // Give a warning if we seem to be looping forever.
 887 
 888     if ((QueuedAllocationWarningCount > 0) &&
 889         (try_count % QueuedAllocationWarningCount == 0)) {
 890       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 891                              Thread::current()->name(), try_count, word_size);
 892     }
 893   }
 894 
 895   ShouldNotReachHere();
 896   return NULL;
 897 }
 898 
 899 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 900                                                            bool expect_null_mutator_alloc_region) {
 901   assert_at_safepoint_on_vm_thread();
 902   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 903          "the current alloc region was unexpectedly found to be non-NULL");
 904 
 905   if (!is_humongous(word_size)) {
 906     return _allocator->attempt_allocation_locked(word_size);
 907   } else {
 908     HeapWord* result = humongous_obj_allocate(word_size);
 909     if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
 910       collector_state()->set_initiate_conc_mark_if_possible(true);
 911     }
 912     return result;
 913   }
 914 
 915   ShouldNotReachHere();
 916 }
 917 
 918 class PostCompactionPrinterClosure: public HeapRegionClosure {
 919 private:
 920   G1HRPrinter* _hr_printer;
 921 public:
 922   bool do_heap_region(HeapRegion* hr) {
 923     assert(!hr->is_young(), "not expecting to find young regions");
 924     _hr_printer->post_compaction(hr);
 925     return false;
 926   }
 927 
 928   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 929     : _hr_printer(hr_printer) { }
 930 };
 931 
 932 void G1CollectedHeap::print_heap_after_full_collection() {
 933   // Post collection region logging.
 934   // We should do this after we potentially resize the heap so
 935   // that all the COMMIT / UNCOMMIT events are generated before
 936   // the compaction events.
 937   if (_hr_printer.is_active()) {
 938     PostCompactionPrinterClosure cl(hr_printer());
 939     heap_region_iterate(&cl);
 940   }
 941 }
 942 
 943 bool G1CollectedHeap::abort_concurrent_cycle() {
 944   // Disable discovery and empty the discovered lists
 945   // for the CM ref processor.
 946   _ref_processor_cm->disable_discovery();
 947   _ref_processor_cm->abandon_partial_discovery();
 948   _ref_processor_cm->verify_no_references_recorded();
 949 
 950   // Abandon current iterations of concurrent marking and concurrent
 951   // refinement, if any are in progress.
 952   return concurrent_mark()->concurrent_cycle_abort();
 953 }
 954 
 955 void G1CollectedHeap::prepare_heap_for_full_collection() {
 956   // Make sure we'll choose a new allocation region afterwards.
 957   _allocator->release_mutator_alloc_regions();
 958   _allocator->abandon_gc_alloc_regions();
 959 
 960   // We may have added regions to the current incremental collection
 961   // set between the last GC or pause and now. We need to clear the
 962   // incremental collection set and then start rebuilding it afresh
 963   // after this full GC.
 964   abandon_collection_set(collection_set());
 965 
 966   _hrm.remove_all_free_regions();
 967 }
 968 
 969 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
 970   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
 971   assert_used_and_recalculate_used_equal(this);
 972   if (!VerifyBeforeGC) {
 973     return;
 974   }
 975   _verifier->verify_region_sets_optional();
 976   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
 977   _verifier->verify_bitmap_clear(true /* above_tams_only */);
 978 }
 979 
 980 void G1CollectedHeap::prepare_for_mutator_after_full_collection() {
 981   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
 982   ClassLoaderDataGraph::purge(/*at_safepoint*/true);
 983   DEBUG_ONLY(MetaspaceUtils::verify();)
 984 
 985   // Prepare heap for normal collections.
 986   assert(num_free_regions() == 0, "we should not have added any free regions");
 987   rebuild_region_sets(false /* free_list_only */);
 988   abort_refinement();
 989   resize_heap_if_necessary();
 990   uncommit_regions_if_necessary();
 991 
 992   // Rebuild the code root lists for each region
 993   rebuild_code_roots();
 994 
 995   start_new_collection_set();
 996   _allocator->init_mutator_alloc_regions();
 997 
 998   // Post collection state updates.
 999   MetaspaceGC::compute_new_size();
1000 }
1001 
1002 void G1CollectedHeap::abort_refinement() {
1003   // Discard all remembered set updates and reset refinement statistics.
1004   G1BarrierSet::dirty_card_queue_set().abandon_logs_and_stats();
1005   assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1006          "DCQS should be empty");
1007   concurrent_refine()->get_and_reset_refinement_stats();
1008 }
1009 
1010 void G1CollectedHeap::verify_after_full_collection() {
1011   if (!VerifyAfterGC) {
1012     return;
1013   }
1014   _hrm.verify_optional();
1015   _verifier->verify_region_sets_optional();
1016   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1017   _verifier->verify_bitmap_clear(false /* above_tams_only */);
1018 
1019   // At this point there should be no regions in the
1020   // entire heap tagged as young.
1021   assert(check_young_list_empty(), "young list should be empty at this point");
1022 
1023   // Note: since we've just done a full GC, concurrent
1024   // marking is no longer active. Therefore we need not
1025   // re-enable reference discovery for the CM ref processor.
1026   // That will be done at the start of the next marking cycle.
1027   // We also know that the STW processor should no longer
1028   // discover any new references.
1029   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1030   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1031   _ref_processor_stw->verify_no_references_recorded();
1032   _ref_processor_cm->verify_no_references_recorded();
1033 }
1034 
1035 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1036                                          bool clear_all_soft_refs,
1037                                          bool do_maximal_compaction) {
1038   assert_at_safepoint_on_vm_thread();
1039 
1040   if (GCLocker::check_active_before_gc()) {
1041     // Full GC was not completed.
1042     return false;
1043   }
1044 
1045   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1046       soft_ref_policy()->should_clear_all_soft_refs();
1047 
1048   G1FullGCMark gc_mark;
1049   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1050   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs, do_maximal_compaction, gc_mark.tracer());
1051 
1052   collector.prepare_collection();
1053   collector.collect();
1054   collector.complete_collection();
1055 
1056   // Full collection was successfully completed.
1057   return true;
1058 }
1059 
1060 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1061   // Currently, there is no facility in the do_full_collection(bool) API to notify
1062   // the caller that the collection did not succeed (e.g., because it was locked
1063   // out by the GC locker). So, right now, we'll ignore the return value.
1064   // When clear_all_soft_refs is set we want to do a maximal compaction
1065   // not leaving any dead wood.
1066   bool do_maximal_compaction = clear_all_soft_refs;
1067   bool dummy = do_full_collection(true,                /* explicit_gc */
1068                                   clear_all_soft_refs,
1069                                   do_maximal_compaction);
1070 }
1071 
1072 bool G1CollectedHeap::upgrade_to_full_collection() {
1073   GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1074   log_info(gc, ergo)("Attempting full compaction clearing soft references");
1075   bool success = do_full_collection(false /* explicit gc */,
1076                                     true  /* clear_all_soft_refs */,
1077                                     false /* do_maximal_compaction */);
1078   // do_full_collection only fails if blocked by GC locker and that can't
1079   // be the case here since we only call this when already completed one gc.
1080   assert(success, "invariant");
1081   return success;
1082 }
1083 
1084 void G1CollectedHeap::resize_heap_if_necessary() {
1085   assert_at_safepoint_on_vm_thread();
1086 
1087   bool should_expand;
1088   size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
1089 
1090   if (resize_amount == 0) {
1091     return;
1092   } else if (should_expand) {
1093     expand(resize_amount, _workers);
1094   } else {
1095     shrink(resize_amount);
1096   }
1097 }
1098 
1099 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1100                                                             bool do_gc,
1101                                                             bool maximal_compaction,
1102                                                             bool expect_null_mutator_alloc_region,
1103                                                             bool* gc_succeeded) {
1104   *gc_succeeded = true;
1105   // Let's attempt the allocation first.
1106   HeapWord* result =
1107     attempt_allocation_at_safepoint(word_size,
1108                                     expect_null_mutator_alloc_region);
1109   if (result != NULL) {
1110     return result;
1111   }
1112 
1113   // In a G1 heap, we're supposed to keep allocation from failing by
1114   // incremental pauses.  Therefore, at least for now, we'll favor
1115   // expansion over collection.  (This might change in the future if we can
1116   // do something smarter than full collection to satisfy a failed alloc.)
1117   result = expand_and_allocate(word_size);
1118   if (result != NULL) {
1119     return result;
1120   }
1121 
1122   if (do_gc) {
1123     GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1124     // Expansion didn't work, we'll try to do a Full GC.
1125     // If maximal_compaction is set we clear all soft references and don't
1126     // allow any dead wood to be left on the heap.
1127     if (maximal_compaction) {
1128       log_info(gc, ergo)("Attempting maximal full compaction clearing soft references");
1129     } else {
1130       log_info(gc, ergo)("Attempting full compaction");
1131     }
1132     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1133                                        maximal_compaction /* clear_all_soft_refs */ ,
1134                                        maximal_compaction /* do_maximal_compaction */);
1135   }
1136 
1137   return NULL;
1138 }
1139 
1140 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1141                                                      bool* succeeded) {
1142   assert_at_safepoint_on_vm_thread();
1143 
1144   // Attempts to allocate followed by Full GC.
1145   HeapWord* result =
1146     satisfy_failed_allocation_helper(word_size,
1147                                      true,  /* do_gc */
1148                                      false, /* maximum_collection */
1149                                      false, /* expect_null_mutator_alloc_region */
1150                                      succeeded);
1151 
1152   if (result != NULL || !*succeeded) {
1153     return result;
1154   }
1155 
1156   // Attempts to allocate followed by Full GC that will collect all soft references.
1157   result = satisfy_failed_allocation_helper(word_size,
1158                                             true, /* do_gc */
1159                                             true, /* maximum_collection */
1160                                             true, /* expect_null_mutator_alloc_region */
1161                                             succeeded);
1162 
1163   if (result != NULL || !*succeeded) {
1164     return result;
1165   }
1166 
1167   // Attempts to allocate, no GC
1168   result = satisfy_failed_allocation_helper(word_size,
1169                                             false, /* do_gc */
1170                                             false, /* maximum_collection */
1171                                             true,  /* expect_null_mutator_alloc_region */
1172                                             succeeded);
1173 
1174   if (result != NULL) {
1175     return result;
1176   }
1177 
1178   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1179          "Flag should have been handled and cleared prior to this point");
1180 
1181   // What else?  We might try synchronous finalization later.  If the total
1182   // space available is large enough for the allocation, then a more
1183   // complete compaction phase than we've tried so far might be
1184   // appropriate.
1185   return NULL;
1186 }
1187 
1188 // Attempting to expand the heap sufficiently
1189 // to support an allocation of the given "word_size".  If
1190 // successful, perform the allocation and return the address of the
1191 // allocated block, or else "NULL".
1192 
1193 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1194   assert_at_safepoint_on_vm_thread();
1195 
1196   _verifier->verify_region_sets_optional();
1197 
1198   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1199   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1200                             word_size * HeapWordSize);
1201 
1202 
1203   if (expand(expand_bytes, _workers)) {
1204     _hrm.verify_optional();
1205     _verifier->verify_region_sets_optional();
1206     return attempt_allocation_at_safepoint(word_size,
1207                                            false /* expect_null_mutator_alloc_region */);
1208   }
1209   return NULL;
1210 }
1211 
1212 bool G1CollectedHeap::expand(size_t expand_bytes, WorkerThreads* pretouch_workers, double* expand_time_ms) {
1213   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1214   aligned_expand_bytes = align_up(aligned_expand_bytes,
1215                                        HeapRegion::GrainBytes);
1216 
1217   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1218                             expand_bytes, aligned_expand_bytes);
1219 
1220   if (is_maximal_no_gc()) {
1221     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1222     return false;
1223   }
1224 
1225   double expand_heap_start_time_sec = os::elapsedTime();
1226   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1227   assert(regions_to_expand > 0, "Must expand by at least one region");
1228 
1229   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1230   if (expand_time_ms != NULL) {
1231     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1232   }
1233 
1234   if (expanded_by > 0) {
1235     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1236     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1237     policy()->record_new_heap_size(num_regions());
1238   } else {
1239     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1240 
1241     // The expansion of the virtual storage space was unsuccessful.
1242     // Let's see if it was because we ran out of swap.
1243     if (G1ExitOnExpansionFailure &&
1244         _hrm.available() >= regions_to_expand) {
1245       // We had head room...
1246       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1247     }
1248   }
1249   return expanded_by > 0;
1250 }
1251 
1252 bool G1CollectedHeap::expand_single_region(uint node_index) {
1253   uint expanded_by = _hrm.expand_on_preferred_node(node_index);
1254 
1255   if (expanded_by == 0) {
1256     assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available());
1257     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1258     return false;
1259   }
1260 
1261   policy()->record_new_heap_size(num_regions());
1262   return true;
1263 }
1264 
1265 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1266   size_t aligned_shrink_bytes =
1267     ReservedSpace::page_align_size_down(shrink_bytes);
1268   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1269                                          HeapRegion::GrainBytes);
1270   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1271 
1272   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1273   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1274 
1275   log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B actual amount shrunk: " SIZE_FORMAT "B",
1276                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1277   if (num_regions_removed > 0) {
1278     log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed);
1279     policy()->record_new_heap_size(num_regions());
1280   } else {
1281     log_debug(gc, ergo, heap)("Did not shrink the heap (heap shrinking operation failed)");
1282   }
1283 }
1284 
1285 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1286   _verifier->verify_region_sets_optional();
1287 
1288   // We should only reach here at the end of a Full GC or during Remark which
1289   // means we should not not be holding to any GC alloc regions. The method
1290   // below will make sure of that and do any remaining clean up.
1291   _allocator->abandon_gc_alloc_regions();
1292 
1293   // Instead of tearing down / rebuilding the free lists here, we
1294   // could instead use the remove_all_pending() method on free_list to
1295   // remove only the ones that we need to remove.
1296   _hrm.remove_all_free_regions();
1297   shrink_helper(shrink_bytes);
1298   rebuild_region_sets(true /* free_list_only */);
1299 
1300   _hrm.verify_optional();
1301   _verifier->verify_region_sets_optional();
1302 }
1303 
1304 class OldRegionSetChecker : public HeapRegionSetChecker {
1305 public:
1306   void check_mt_safety() {
1307     // Master Old Set MT safety protocol:
1308     // (a) If we're at a safepoint, operations on the master old set
1309     // should be invoked:
1310     // - by the VM thread (which will serialize them), or
1311     // - by the GC workers while holding the FreeList_lock, if we're
1312     //   at a safepoint for an evacuation pause (this lock is taken
1313     //   anyway when an GC alloc region is retired so that a new one
1314     //   is allocated from the free list), or
1315     // - by the GC workers while holding the OldSets_lock, if we're at a
1316     //   safepoint for a cleanup pause.
1317     // (b) If we're not at a safepoint, operations on the master old set
1318     // should be invoked while holding the Heap_lock.
1319 
1320     if (SafepointSynchronize::is_at_safepoint()) {
1321       guarantee(Thread::current()->is_VM_thread() ||
1322                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1323                 "master old set MT safety protocol at a safepoint");
1324     } else {
1325       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1326     }
1327   }
1328   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1329   const char* get_description() { return "Old Regions"; }
1330 };
1331 
1332 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1333 public:
1334   void check_mt_safety() {
1335     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1336               "May only change archive regions during initialization or safepoint.");
1337   }
1338   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1339   const char* get_description() { return "Archive Regions"; }
1340 };
1341 
1342 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1343 public:
1344   void check_mt_safety() {
1345     // Humongous Set MT safety protocol:
1346     // (a) If we're at a safepoint, operations on the master humongous
1347     // set should be invoked by either the VM thread (which will
1348     // serialize them) or by the GC workers while holding the
1349     // OldSets_lock.
1350     // (b) If we're not at a safepoint, operations on the master
1351     // humongous set should be invoked while holding the Heap_lock.
1352 
1353     if (SafepointSynchronize::is_at_safepoint()) {
1354       guarantee(Thread::current()->is_VM_thread() ||
1355                 OldSets_lock->owned_by_self(),
1356                 "master humongous set MT safety protocol at a safepoint");
1357     } else {
1358       guarantee(Heap_lock->owned_by_self(),
1359                 "master humongous set MT safety protocol outside a safepoint");
1360     }
1361   }
1362   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1363   const char* get_description() { return "Humongous Regions"; }
1364 };
1365 
1366 G1CollectedHeap::G1CollectedHeap() :
1367   CollectedHeap(),
1368   _service_thread(NULL),
1369   _periodic_gc_task(NULL),
1370   _free_arena_memory_task(NULL),
1371   _workers(NULL),
1372   _card_table(NULL),
1373   _collection_pause_end(Ticks::now()),
1374   _soft_ref_policy(),
1375   _old_set("Old Region Set", new OldRegionSetChecker()),
1376   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1377   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1378   _bot(NULL),
1379   _listener(),
1380   _numa(G1NUMA::create()),
1381   _hrm(),
1382   _allocator(NULL),
1383   _evac_failure_injector(),
1384   _verifier(NULL),
1385   _summary_bytes_used(0),
1386   _bytes_used_during_gc(0),
1387   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1388   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1389   _monitoring_support(nullptr),
1390   _num_humongous_objects(0),
1391   _num_humongous_reclaim_candidates(0),
1392   _hr_printer(),
1393   _collector_state(),
1394   _old_marking_cycles_started(0),
1395   _old_marking_cycles_completed(0),
1396   _eden(),
1397   _survivor(),
1398   _gc_timer_stw(new STWGCTimer()),
1399   _gc_tracer_stw(new G1NewTracer()),
1400   _policy(new G1Policy(_gc_timer_stw)),
1401   _heap_sizing_policy(NULL),
1402   _collection_set(this, _policy),
1403   _rem_set(NULL),
1404   _card_set_config(),
1405   _card_set_freelist_pool(G1CardSetConfiguration::num_mem_object_types()),
1406   _cm(NULL),
1407   _cm_thread(NULL),
1408   _cr(NULL),
1409   _task_queues(NULL),
1410   _ref_processor_stw(NULL),
1411   _is_alive_closure_stw(this),
1412   _is_subject_to_discovery_stw(this),
1413   _ref_processor_cm(NULL),
1414   _is_alive_closure_cm(this),
1415   _is_subject_to_discovery_cm(this),
1416   _region_attr() {
1417 
1418   _verifier = new G1HeapVerifier(this);
1419 
1420   _allocator = new G1Allocator(this);
1421 
1422   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1423 
1424   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1425 
1426   // Override the default _filler_array_max_size so that no humongous filler
1427   // objects are created.
1428   _filler_array_max_size = _humongous_object_threshold_in_words;
1429 
1430   // Override the default _stack_chunk_max_size so that no humongous stack chunks are created
1431   _stack_chunk_max_size = _humongous_object_threshold_in_words;
1432 
1433   uint n_queues = ParallelGCThreads;
1434   _task_queues = new G1ScannerTasksQueueSet(n_queues);
1435 
1436   for (uint i = 0; i < n_queues; i++) {
1437     G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1438     _task_queues->register_queue(i, q);
1439   }
1440 
1441   _gc_tracer_stw->initialize();
1442 
1443   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1444 }
1445 
1446 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1447                                                                  size_t size,
1448                                                                  size_t translation_factor) {
1449   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1450   // Allocate a new reserved space, preferring to use large pages.
1451   ReservedSpace rs(size, preferred_page_size);
1452   size_t page_size = rs.page_size();
1453   G1RegionToSpaceMapper* result  =
1454     G1RegionToSpaceMapper::create_mapper(rs,
1455                                          size,
1456                                          page_size,
1457                                          HeapRegion::GrainBytes,
1458                                          translation_factor,
1459                                          mtGC);
1460 
1461   os::trace_page_sizes_for_requested_size(description,
1462                                           size,
1463                                           page_size,
1464                                           preferred_page_size,
1465                                           rs.base(),
1466                                           rs.size());
1467 
1468   return result;
1469 }
1470 
1471 jint G1CollectedHeap::initialize_concurrent_refinement() {
1472   jint ecode = JNI_OK;
1473   _cr = G1ConcurrentRefine::create(policy(), &ecode);
1474   return ecode;
1475 }
1476 
1477 jint G1CollectedHeap::initialize_service_thread() {
1478   _service_thread = new G1ServiceThread();
1479   if (_service_thread->osthread() == NULL) {
1480     vm_shutdown_during_initialization("Could not create G1ServiceThread");
1481     return JNI_ENOMEM;
1482   }
1483   return JNI_OK;
1484 }
1485 
1486 jint G1CollectedHeap::initialize() {
1487 
1488   // Necessary to satisfy locking discipline assertions.
1489 
1490   MutexLocker x(Heap_lock);
1491 
1492   // While there are no constraints in the GC code that HeapWordSize
1493   // be any particular value, there are multiple other areas in the
1494   // system which believe this to be true (e.g. oop->object_size in some
1495   // cases incorrectly returns the size in wordSize units rather than
1496   // HeapWordSize).
1497   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1498 
1499   size_t init_byte_size = InitialHeapSize;
1500   size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1501 
1502   // Ensure that the sizes are properly aligned.
1503   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1504   Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1505   Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1506 
1507   // Reserve the maximum.
1508 
1509   // When compressed oops are enabled, the preferred heap base
1510   // is calculated by subtracting the requested size from the
1511   // 32Gb boundary and using the result as the base address for
1512   // heap reservation. If the requested size is not aligned to
1513   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1514   // into the ReservedHeapSpace constructor) then the actual
1515   // base of the reserved heap may end up differing from the
1516   // address that was requested (i.e. the preferred heap base).
1517   // If this happens then we could end up using a non-optimal
1518   // compressed oops mode.
1519 
1520   ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1521                                                      HeapAlignment);
1522 
1523   initialize_reserved_region(heap_rs);
1524 
1525   _forwarding = new SlidingForwarding(heap_rs.region(), HeapRegion::LogOfHRGrainBytes - LogHeapWordSize);
1526 
1527   // Create the barrier set for the entire reserved region.
1528   G1CardTable* ct = new G1CardTable(heap_rs.region());
1529   ct->initialize();
1530   G1BarrierSet* bs = new G1BarrierSet(ct);
1531   bs->initialize();
1532   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1533   BarrierSet::set_barrier_set(bs);
1534   _card_table = ct;
1535 
1536   {
1537     G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1538     satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1539     satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1540   }
1541 
1542   // Create space mappers.
1543   size_t page_size = heap_rs.page_size();
1544   G1RegionToSpaceMapper* heap_storage =
1545     G1RegionToSpaceMapper::create_mapper(heap_rs,
1546                                          heap_rs.size(),
1547                                          page_size,
1548                                          HeapRegion::GrainBytes,
1549                                          1,
1550                                          mtJavaHeap);
1551   if(heap_storage == NULL) {
1552     vm_shutdown_during_initialization("Could not initialize G1 heap");
1553     return JNI_ERR;
1554   }
1555 
1556   os::trace_page_sizes("Heap",
1557                        MinHeapSize,
1558                        reserved_byte_size,
1559                        page_size,
1560                        heap_rs.base(),
1561                        heap_rs.size());
1562   heap_storage->set_mapping_changed_listener(&_listener);
1563 
1564   // Create storage for the BOT, card table and the bitmap.
1565   G1RegionToSpaceMapper* bot_storage =
1566     create_aux_memory_mapper("Block Offset Table",
1567                              G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1568                              G1BlockOffsetTable::heap_map_factor());
1569 
1570   G1RegionToSpaceMapper* cardtable_storage =
1571     create_aux_memory_mapper("Card Table",
1572                              G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1573                              G1CardTable::heap_map_factor());
1574 
1575   size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1576   G1RegionToSpaceMapper* bitmap_storage =
1577     create_aux_memory_mapper("Mark Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1578 
1579   _hrm.initialize(heap_storage, bitmap_storage, bot_storage, cardtable_storage);
1580   _card_table->initialize(cardtable_storage);
1581 
1582   // 6843694 - ensure that the maximum region index can fit
1583   // in the remembered set structures.
1584   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1585   guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");
1586 
1587   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1588   // start within the first card.
1589   guarantee((uintptr_t)(heap_rs.base()) >= G1CardTable::card_size(), "Java heap must not start within the first card.");
1590   G1FromCardCache::initialize(max_reserved_regions());
1591   // Also create a G1 rem set.
1592   _rem_set = new G1RemSet(this, _card_table);
1593   _rem_set->initialize(max_reserved_regions());
1594 
1595   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1596   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1597   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1598             "too many cards per region");
1599 
1600   HeapRegionRemSet::initialize(_reserved);
1601 
1602   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1603 
1604   _bot = new G1BlockOffsetTable(reserved(), bot_storage);
1605 
1606   {
1607     size_t granularity = HeapRegion::GrainBytes;
1608 
1609     _region_attr.initialize(reserved(), granularity);
1610   }
1611 
1612   _workers = new WorkerThreads("GC Thread", ParallelGCThreads);
1613   if (_workers == NULL) {
1614     return JNI_ENOMEM;
1615   }
1616   _workers->initialize_workers();
1617 
1618   _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1619 
1620   // Create the G1ConcurrentMark data structure and thread.
1621   // (Must do this late, so that "max_[reserved_]regions" is defined.)
1622   _cm = new G1ConcurrentMark(this, bitmap_storage);
1623   _cm_thread = _cm->cm_thread();
1624 
1625   // Now expand into the initial heap size.
1626   if (!expand(init_byte_size, _workers)) {
1627     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1628     return JNI_ENOMEM;
1629   }
1630 
1631   // Perform any initialization actions delegated to the policy.
1632   policy()->init(this, &_collection_set);
1633 
1634   jint ecode = initialize_concurrent_refinement();
1635   if (ecode != JNI_OK) {
1636     return ecode;
1637   }
1638 
1639   ecode = initialize_service_thread();
1640   if (ecode != JNI_OK) {
1641     return ecode;
1642   }
1643 
1644   // Create and schedule the periodic gc task on the service thread.
1645   _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");
1646   _service_thread->register_task(_periodic_gc_task);
1647 
1648   _free_arena_memory_task = new G1MonotonicArenaFreeMemoryTask("Card Set Free Memory Task");
1649   _service_thread->register_task(_free_arena_memory_task);
1650 
1651   // Here we allocate the dummy HeapRegion that is required by the
1652   // G1AllocRegion class.
1653   HeapRegion* dummy_region = _hrm.get_dummy_region();
1654 
1655   // We'll re-use the same region whether the alloc region will
1656   // require BOT updates or not and, if it doesn't, then a non-young
1657   // region will complain that it cannot support allocations without
1658   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1659   dummy_region->set_eden();
1660   // Make sure it's full.
1661   dummy_region->set_top(dummy_region->end());
1662   G1AllocRegion::setup(this, dummy_region);
1663 
1664   _allocator->init_mutator_alloc_regions();
1665 
1666   // Do create of the monitoring and management support so that
1667   // values in the heap have been properly initialized.
1668   _monitoring_support = new G1MonitoringSupport(this);
1669 
1670   _collection_set.initialize(max_reserved_regions());
1671 
1672   evac_failure_injector()->reset();
1673 
1674   G1InitLogger::print();
1675 
1676   return JNI_OK;
1677 }
1678 
1679 bool G1CollectedHeap::concurrent_mark_is_terminating() const {
1680   return _cm_thread->should_terminate();
1681 }
1682 
1683 void G1CollectedHeap::stop() {
1684   // Stop all concurrent threads. We do this to make sure these threads
1685   // do not continue to execute and access resources (e.g. logging)
1686   // that are destroyed during shutdown.
1687   _cr->stop();
1688   _service_thread->stop();
1689   _cm_thread->stop();
1690 }
1691 
1692 void G1CollectedHeap::safepoint_synchronize_begin() {
1693   SuspendibleThreadSet::synchronize();
1694 }
1695 
1696 void G1CollectedHeap::safepoint_synchronize_end() {
1697   SuspendibleThreadSet::desynchronize();
1698 }
1699 
1700 void G1CollectedHeap::post_initialize() {
1701   CollectedHeap::post_initialize();
1702   ref_processing_init();
1703 }
1704 
1705 void G1CollectedHeap::ref_processing_init() {
1706   // Reference processing in G1 currently works as follows:
1707   //
1708   // * There are two reference processor instances. One is
1709   //   used to record and process discovered references
1710   //   during concurrent marking; the other is used to
1711   //   record and process references during STW pauses
1712   //   (both full and incremental).
1713   // * Both ref processors need to 'span' the entire heap as
1714   //   the regions in the collection set may be dotted around.
1715   //
1716   // * For the concurrent marking ref processor:
1717   //   * Reference discovery is enabled at concurrent start.
1718   //   * Reference discovery is disabled and the discovered
1719   //     references processed etc during remarking.
1720   //   * Reference discovery is MT (see below).
1721   //   * Reference discovery requires a barrier (see below).
1722   //   * Reference processing may or may not be MT
1723   //     (depending on the value of ParallelRefProcEnabled
1724   //     and ParallelGCThreads).
1725   //   * A full GC disables reference discovery by the CM
1726   //     ref processor and abandons any entries on it's
1727   //     discovered lists.
1728   //
1729   // * For the STW processor:
1730   //   * Non MT discovery is enabled at the start of a full GC.
1731   //   * Processing and enqueueing during a full GC is non-MT.
1732   //   * During a full GC, references are processed after marking.
1733   //
1734   //   * Discovery (may or may not be MT) is enabled at the start
1735   //     of an incremental evacuation pause.
1736   //   * References are processed near the end of a STW evacuation pause.
1737   //   * For both types of GC:
1738   //     * Discovery is atomic - i.e. not concurrent.
1739   //     * Reference discovery will not need a barrier.
1740 
1741   // Concurrent Mark ref processor
1742   _ref_processor_cm =
1743     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1744                            ParallelGCThreads,                              // degree of mt processing
1745                            // We discover with the gc worker threads during Remark, so both
1746                            // thread counts must be considered for discovery.
1747                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1748                            true,                                           // Reference discovery is concurrent
1749                            &_is_alive_closure_cm);                         // is alive closure
1750 
1751   // STW ref processor
1752   _ref_processor_stw =
1753     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1754                            ParallelGCThreads,                    // degree of mt processing
1755                            ParallelGCThreads,                    // degree of mt discovery
1756                            false,                                // Reference discovery is not concurrent
1757                            &_is_alive_closure_stw);              // is alive closure
1758 }
1759 
1760 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1761   return &_soft_ref_policy;
1762 }
1763 
1764 size_t G1CollectedHeap::capacity() const {
1765   return _hrm.length() * HeapRegion::GrainBytes;
1766 }
1767 
1768 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1769   return _hrm.total_free_bytes();
1770 }
1771 
1772 // Computes the sum of the storage used by the various regions.
1773 size_t G1CollectedHeap::used() const {
1774   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1775   return result;
1776 }
1777 
1778 size_t G1CollectedHeap::used_unlocked() const {
1779   return _summary_bytes_used;
1780 }
1781 
1782 class SumUsedClosure: public HeapRegionClosure {
1783   size_t _used;
1784 public:
1785   SumUsedClosure() : _used(0) {}
1786   bool do_heap_region(HeapRegion* r) {
1787     _used += r->used();
1788     return false;
1789   }
1790   size_t result() { return _used; }
1791 };
1792 
1793 size_t G1CollectedHeap::recalculate_used() const {
1794   SumUsedClosure blk;
1795   heap_region_iterate(&blk);
1796   return blk.result();
1797 }
1798 
1799 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1800   return GCCause::is_user_requested_gc(cause) && ExplicitGCInvokesConcurrent;
1801 }
1802 
1803 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1804   switch (cause) {
1805     case GCCause::_g1_humongous_allocation: return true;
1806     case GCCause::_g1_periodic_collection:  return G1PeriodicGCInvokesConcurrent;
1807     case GCCause::_wb_breakpoint:           return true;
1808     case GCCause::_codecache_GC_aggressive: return true;
1809     case GCCause::_codecache_GC_threshold:  return true;
1810     default:                                return is_user_requested_concurrent_full_gc(cause);
1811   }
1812 }
1813 
1814 void G1CollectedHeap::increment_old_marking_cycles_started() {
1815   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1816          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1817          "Wrong marking cycle count (started: %d, completed: %d)",
1818          _old_marking_cycles_started, _old_marking_cycles_completed);
1819 
1820   _old_marking_cycles_started++;
1821 }
1822 
1823 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1824                                                              bool whole_heap_examined) {
1825   MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1826 
1827   // We assume that if concurrent == true, then the caller is a
1828   // concurrent thread that was joined the Suspendible Thread
1829   // Set. If there's ever a cheap way to check this, we should add an
1830   // assert here.
1831 
1832   // Given that this method is called at the end of a Full GC or of a
1833   // concurrent cycle, and those can be nested (i.e., a Full GC can
1834   // interrupt a concurrent cycle), the number of full collections
1835   // completed should be either one (in the case where there was no
1836   // nesting) or two (when a Full GC interrupted a concurrent cycle)
1837   // behind the number of full collections started.
1838 
1839   // This is the case for the inner caller, i.e. a Full GC.
1840   assert(concurrent ||
1841          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1842          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1843          "for inner caller (Full GC): _old_marking_cycles_started = %u "
1844          "is inconsistent with _old_marking_cycles_completed = %u",
1845          _old_marking_cycles_started, _old_marking_cycles_completed);
1846 
1847   // This is the case for the outer caller, i.e. the concurrent cycle.
1848   assert(!concurrent ||
1849          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1850          "for outer caller (concurrent cycle): "
1851          "_old_marking_cycles_started = %u "
1852          "is inconsistent with _old_marking_cycles_completed = %u",
1853          _old_marking_cycles_started, _old_marking_cycles_completed);
1854 
1855   _old_marking_cycles_completed += 1;
1856   if (whole_heap_examined) {
1857     // Signal that we have completed a visit to all live objects.
1858     record_whole_heap_examined_timestamp();
1859   }
1860 
1861   // We need to clear the "in_progress" flag in the CM thread before
1862   // we wake up any waiters (especially when ExplicitInvokesConcurrent
1863   // is set) so that if a waiter requests another System.gc() it doesn't
1864   // incorrectly see that a marking cycle is still in progress.
1865   if (concurrent) {
1866     _cm_thread->set_idle();
1867   }
1868 
1869   // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
1870   // for a full GC to finish that their wait is over.
1871   ml.notify_all();
1872 }
1873 
1874 // Helper for collect().
1875 static G1GCCounters collection_counters(G1CollectedHeap* g1h) {
1876   MutexLocker ml(Heap_lock);
1877   return G1GCCounters(g1h);
1878 }
1879 
1880 void G1CollectedHeap::collect(GCCause::Cause cause) {
1881   try_collect(cause, collection_counters(this));
1882 }
1883 
1884 // Return true if (x < y) with allowance for wraparound.
1885 static bool gc_counter_less_than(uint x, uint y) {
1886   return (x - y) > (UINT_MAX/2);
1887 }
1888 
1889 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
1890 // Macro so msg printing is format-checked.
1891 #define LOG_COLLECT_CONCURRENTLY(cause, ...)                            \
1892   do {                                                                  \
1893     LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt;                   \
1894     if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) {                     \
1895       ResourceMark rm; /* For thread name. */                           \
1896       LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
1897       LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
1898                                        Thread::current()->name(),       \
1899                                        GCCause::to_string(cause));      \
1900       LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__);                    \
1901     }                                                                   \
1902   } while (0)
1903 
1904 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
1905   LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
1906 
1907 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
1908                                                uint gc_counter,
1909                                                uint old_marking_started_before) {
1910   assert_heap_not_locked();
1911   assert(should_do_concurrent_full_gc(cause),
1912          "Non-concurrent cause %s", GCCause::to_string(cause));
1913 
1914   for (uint i = 1; true; ++i) {
1915     // Try to schedule concurrent start evacuation pause that will
1916     // start a concurrent cycle.
1917     LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
1918     VM_G1TryInitiateConcMark op(gc_counter, cause);
1919     VMThread::execute(&op);
1920 
1921     // Request is trivially finished.
1922     if (cause == GCCause::_g1_periodic_collection) {
1923       LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
1924       return op.gc_succeeded();
1925     }
1926 
1927     // If VMOp skipped initiating concurrent marking cycle because
1928     // we're terminating, then we're done.
1929     if (op.terminating()) {
1930       LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
1931       return false;
1932     }
1933 
1934     // Lock to get consistent set of values.
1935     uint old_marking_started_after;
1936     uint old_marking_completed_after;
1937     {
1938       MutexLocker ml(Heap_lock);
1939       // Update gc_counter for retrying VMOp if needed. Captured here to be
1940       // consistent with the values we use below for termination tests.  If
1941       // a retry is needed after a possible wait, and another collection
1942       // occurs in the meantime, it will cause our retry to be skipped and
1943       // we'll recheck for termination with updated conditions from that
1944       // more recent collection.  That's what we want, rather than having
1945       // our retry possibly perform an unnecessary collection.
1946       gc_counter = total_collections();
1947       old_marking_started_after = _old_marking_cycles_started;
1948       old_marking_completed_after = _old_marking_cycles_completed;
1949     }
1950 
1951     if (cause == GCCause::_wb_breakpoint) {
1952       if (op.gc_succeeded()) {
1953         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1954         return true;
1955       }
1956       // When _wb_breakpoint there can't be another cycle or deferred.
1957       assert(!op.cycle_already_in_progress(), "invariant");
1958       assert(!op.whitebox_attached(), "invariant");
1959       // Concurrent cycle attempt might have been cancelled by some other
1960       // collection, so retry.  Unlike other cases below, we want to retry
1961       // even if cancelled by a STW full collection, because we really want
1962       // to start a concurrent cycle.
1963       if (old_marking_started_before != old_marking_started_after) {
1964         LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
1965         old_marking_started_before = old_marking_started_after;
1966       }
1967     } else if (!GCCause::is_user_requested_gc(cause)) {
1968       // For an "automatic" (not user-requested) collection, we just need to
1969       // ensure that progress is made.
1970       //
1971       // Request is finished if any of
1972       // (1) the VMOp successfully performed a GC,
1973       // (2) a concurrent cycle was already in progress,
1974       // (3) whitebox is controlling concurrent cycles,
1975       // (4) a new cycle was started (by this thread or some other), or
1976       // (5) a Full GC was performed.
1977       // Cases (4) and (5) are detected together by a change to
1978       // _old_marking_cycles_started.
1979       //
1980       // Note that (1) does not imply (4).  If we're still in the mixed
1981       // phase of an earlier concurrent collection, the request to make the
1982       // collection a concurrent start won't be honored.  If we don't check for
1983       // both conditions we'll spin doing back-to-back collections.
1984       if (op.gc_succeeded() ||
1985           op.cycle_already_in_progress() ||
1986           op.whitebox_attached() ||
1987           (old_marking_started_before != old_marking_started_after)) {
1988         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1989         return true;
1990       }
1991     } else {                    // User-requested GC.
1992       // For a user-requested collection, we want to ensure that a complete
1993       // full collection has been performed before returning, but without
1994       // waiting for more than needed.
1995 
1996       // For user-requested GCs (unlike non-UR), a successful VMOp implies a
1997       // new cycle was started.  That's good, because it's not clear what we
1998       // should do otherwise.  Trying again just does back to back GCs.
1999       // Can't wait for someone else to start a cycle.  And returning fails
2000       // to meet the goal of ensuring a full collection was performed.
2001       assert(!op.gc_succeeded() ||
2002              (old_marking_started_before != old_marking_started_after),
2003              "invariant: succeeded %s, started before %u, started after %u",
2004              BOOL_TO_STR(op.gc_succeeded()),
2005              old_marking_started_before, old_marking_started_after);
2006 
2007       // Request is finished if a full collection (concurrent or stw)
2008       // was started after this request and has completed, e.g.
2009       // started_before < completed_after.
2010       if (gc_counter_less_than(old_marking_started_before,
2011                                old_marking_completed_after)) {
2012         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2013         return true;
2014       }
2015 
2016       if (old_marking_started_after != old_marking_completed_after) {
2017         // If there is an in-progress cycle (possibly started by us), then
2018         // wait for that cycle to complete, e.g.
2019         // while completed_now < started_after.
2020         LOG_COLLECT_CONCURRENTLY(cause, "wait");
2021         MonitorLocker ml(G1OldGCCount_lock);
2022         while (gc_counter_less_than(_old_marking_cycles_completed,
2023                                     old_marking_started_after)) {
2024           ml.wait();
2025         }
2026         // Request is finished if the collection we just waited for was
2027         // started after this request.
2028         if (old_marking_started_before != old_marking_started_after) {
2029           LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2030           return true;
2031         }
2032       }
2033 
2034       // If VMOp was successful then it started a new cycle that the above
2035       // wait &etc should have recognized as finishing this request.  This
2036       // differs from a non-user-request, where gc_succeeded does not imply
2037       // a new cycle was started.
2038       assert(!op.gc_succeeded(), "invariant");
2039 
2040       if (op.cycle_already_in_progress()) {
2041         // If VMOp failed because a cycle was already in progress, it
2042         // is now complete.  But it didn't finish this user-requested
2043         // GC, so try again.
2044         LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2045         continue;
2046       } else if (op.whitebox_attached()) {
2047         // If WhiteBox wants control, wait for notification of a state
2048         // change in the controller, then try again.  Don't wait for
2049         // release of control, since collections may complete while in
2050         // control.  Note: This won't recognize a STW full collection
2051         // while waiting; we can't wait on multiple monitors.
2052         LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2053         MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2054         if (ConcurrentGCBreakpoints::is_controlled()) {
2055           ml.wait();
2056         }
2057         continue;
2058       }
2059     }
2060 
2061     // Collection failed and should be retried.
2062     assert(op.transient_failure(), "invariant");
2063 
2064     if (GCLocker::is_active_and_needs_gc()) {
2065       // If GCLocker is active, wait until clear before retrying.
2066       LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2067       GCLocker::stall_until_clear();
2068     }
2069 
2070     LOG_COLLECT_CONCURRENTLY(cause, "retry");
2071   }
2072 }
2073 
2074 bool G1CollectedHeap::try_collect(GCCause::Cause cause,
2075                                   const G1GCCounters& counters_before) {
2076   if (should_do_concurrent_full_gc(cause)) {
2077     return try_collect_concurrently(cause,
2078                                     counters_before.total_collections(),
2079                                     counters_before.old_marking_cycles_started());
2080   } else if (GCLocker::should_discard(cause, counters_before.total_collections())) {
2081     // Indicate failure to be consistent with VMOp failure due to
2082     // another collection slipping in after our gc_count but before
2083     // our request is processed.
2084     return false;
2085   } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2086              DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2087 
2088     // Schedule a standard evacuation pause. We're setting word_size
2089     // to 0 which means that we are not requesting a post-GC allocation.
2090     VM_G1CollectForAllocation op(0,     /* word_size */
2091                                  counters_before.total_collections(),
2092                                  cause);
2093     VMThread::execute(&op);
2094     return op.gc_succeeded();
2095   } else {
2096     // Schedule a Full GC.
2097     VM_G1CollectFull op(counters_before.total_collections(),
2098                         counters_before.total_full_collections(),
2099                         cause);
2100     VMThread::execute(&op);
2101     return op.gc_succeeded();
2102   }
2103 }
2104 
2105 void G1CollectedHeap::start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause) {
2106   GCCauseSetter x(this, gc_cause);
2107 
2108   // At this point we are supposed to start a concurrent cycle. We
2109   // will do so if one is not already in progress.
2110   bool should_start = policy()->force_concurrent_start_if_outside_cycle(gc_cause);
2111   if (should_start) {
2112     do_collection_pause_at_safepoint();
2113   }
2114 }
2115 
2116 bool G1CollectedHeap::is_in(const void* p) const {
2117   return is_in_reserved(p) && _hrm.is_available(addr_to_region(p));
2118 }
2119 
2120 // Iteration functions.
2121 
2122 // Iterates an ObjectClosure over all objects within a HeapRegion.
2123 
2124 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2125   ObjectClosure* _cl;
2126 public:
2127   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2128   bool do_heap_region(HeapRegion* r) {
2129     if (!r->is_continues_humongous()) {
2130       r->object_iterate(_cl);
2131     }
2132     return false;
2133   }
2134 };
2135 
2136 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2137   IterateObjectClosureRegionClosure blk(cl);
2138   heap_region_iterate(&blk);
2139 }
2140 
2141 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl {
2142 private:
2143   G1CollectedHeap*  _heap;
2144   HeapRegionClaimer _claimer;
2145 
2146 public:
2147   G1ParallelObjectIterator(uint thread_num) :
2148       _heap(G1CollectedHeap::heap()),
2149       _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2150 
2151   virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2152     _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2153   }
2154 };
2155 
2156 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2157   return new G1ParallelObjectIterator(thread_num);
2158 }
2159 
2160 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2161   IterateObjectClosureRegionClosure blk(cl);
2162   heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2163 }
2164 
2165 void G1CollectedHeap::keep_alive(oop obj) {
2166   G1BarrierSet::enqueue_preloaded(obj);
2167 }
2168 
2169 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2170   _hrm.iterate(cl);
2171 }
2172 
2173 void G1CollectedHeap::heap_region_iterate(HeapRegionIndexClosure* cl) const {
2174   _hrm.iterate(cl);
2175 }
2176 
2177 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2178                                                                  HeapRegionClaimer *hrclaimer,
2179                                                                  uint worker_id) const {
2180   _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2181 }
2182 
2183 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2184                                                          HeapRegionClaimer *hrclaimer) const {
2185   _hrm.par_iterate(cl, hrclaimer, 0);
2186 }
2187 
2188 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2189   _collection_set.iterate(cl);
2190 }
2191 
2192 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl,
2193                                                      HeapRegionClaimer* hr_claimer,
2194                                                      uint worker_id) {
2195   _collection_set.par_iterate(cl, hr_claimer, worker_id);
2196 }
2197 
2198 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl,
2199                                                             HeapRegionClaimer* hr_claimer,
2200                                                             uint worker_id) {
2201   _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id);
2202 }
2203 
2204 void G1CollectedHeap::par_iterate_regions_array(HeapRegionClosure* cl,
2205                                                 HeapRegionClaimer* hr_claimer,
2206                                                 const uint regions[],
2207                                                 size_t length,
2208                                                 uint worker_id) const {
2209   assert_at_safepoint();
2210   if (length == 0) {
2211     return;
2212   }
2213   uint total_workers = workers()->active_workers();
2214 
2215   size_t start_pos = (worker_id * length) / total_workers;
2216   size_t cur_pos = start_pos;
2217 
2218   do {
2219     uint region_idx = regions[cur_pos];
2220     if (hr_claimer == NULL || hr_claimer->claim_region(region_idx)) {
2221       HeapRegion* r = region_at(region_idx);
2222       bool result = cl->do_heap_region(r);
2223       guarantee(!result, "Must not cancel iteration");
2224     }
2225 
2226     cur_pos++;
2227     if (cur_pos == length) {
2228       cur_pos = 0;
2229     }
2230   } while (cur_pos != start_pos);
2231 }
2232 
2233 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2234   HeapRegion* hr = heap_region_containing(addr);
2235   // The CollectedHeap API requires us to not fail for any given address within
2236   // the heap. HeapRegion::block_start() has been optimized to not accept addresses
2237   // outside of the allocated area.
2238   if (addr >= hr->top()) {
2239     return nullptr;
2240   }
2241   return hr->block_start(addr);
2242 }
2243 
2244 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2245   HeapRegion* hr = heap_region_containing(addr);
2246   return hr->block_is_obj(addr, hr->parsable_bottom_acquire());
2247 }
2248 
2249 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2250   return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2251 }
2252 
2253 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2254   return _eden.length() * HeapRegion::GrainBytes;
2255 }
2256 
2257 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2258 // must be equal to the humongous object limit.
2259 size_t G1CollectedHeap::max_tlab_size() const {
2260   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2261 }
2262 
2263 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2264   return _allocator->unsafe_max_tlab_alloc();
2265 }
2266 
2267 size_t G1CollectedHeap::max_capacity() const {
2268   return max_regions() * HeapRegion::GrainBytes;
2269 }
2270 
2271 void G1CollectedHeap::prepare_for_verify() {
2272   _verifier->prepare_for_verify();
2273 }
2274 
2275 void G1CollectedHeap::verify(VerifyOption vo) {
2276   _verifier->verify(vo);
2277 }
2278 
2279 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2280   return true;
2281 }
2282 
2283 bool G1CollectedHeap::is_archived_object(oop object) const {
2284   return object != NULL && heap_region_containing(object)->is_archive();
2285 }
2286 
2287 class PrintRegionClosure: public HeapRegionClosure {
2288   outputStream* _st;
2289 public:
2290   PrintRegionClosure(outputStream* st) : _st(st) {}
2291   bool do_heap_region(HeapRegion* r) {
2292     r->print_on(_st);
2293     return false;
2294   }
2295 };
2296 
2297 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2298                                        const HeapRegion* hr,
2299                                        const VerifyOption vo) const {
2300   switch (vo) {
2301     case VerifyOption::G1UseConcMarking: return is_obj_dead(obj, hr);
2302     case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj, hr);
2303     default:                             ShouldNotReachHere();
2304   }
2305   return false; // keep some compilers happy
2306 }
2307 
2308 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2309                                        const VerifyOption vo) const {
2310   switch (vo) {
2311     case VerifyOption::G1UseConcMarking: return is_obj_dead(obj);
2312     case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj);
2313     default:                             ShouldNotReachHere();
2314   }
2315   return false; // keep some compilers happy
2316 }
2317 
2318 void G1CollectedHeap::pin_object(JavaThread* thread, oop obj) {
2319   GCLocker::lock_critical(thread);
2320 }
2321 
2322 void G1CollectedHeap::unpin_object(JavaThread* thread, oop obj) {
2323   GCLocker::unlock_critical(thread);
2324 }
2325 
2326 void G1CollectedHeap::print_heap_regions() const {
2327   LogTarget(Trace, gc, heap, region) lt;
2328   if (lt.is_enabled()) {
2329     LogStream ls(lt);
2330     print_regions_on(&ls);
2331   }
2332 }
2333 
2334 void G1CollectedHeap::print_on(outputStream* st) const {
2335   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2336   st->print(" %-20s", "garbage-first heap");
2337   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2338             capacity()/K, heap_used/K);
2339   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2340             p2i(_hrm.reserved().start()),
2341             p2i(_hrm.reserved().end()));
2342   st->cr();
2343   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2344   uint young_regions = young_regions_count();
2345   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2346             (size_t) young_regions * HeapRegion::GrainBytes / K);
2347   uint survivor_regions = survivor_regions_count();
2348   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2349             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2350   st->cr();
2351   if (_numa->is_enabled()) {
2352     uint num_nodes = _numa->num_active_nodes();
2353     st->print("  remaining free region(s) on each NUMA node: ");
2354     const int* node_ids = _numa->node_ids();
2355     for (uint node_index = 0; node_index < num_nodes; node_index++) {
2356       uint num_free_regions = _hrm.num_free_regions(node_index);
2357       st->print("%d=%u ", node_ids[node_index], num_free_regions);
2358     }
2359     st->cr();
2360   }
2361   MetaspaceUtils::print_on(st);
2362 }
2363 
2364 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2365   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2366                "HS=humongous(starts), HC=humongous(continues), "
2367                "CS=collection set, F=free, "
2368                "OA=open archive, CA=closed archive, "
2369                "TAMS=top-at-mark-start, "
2370                "PB=parsable bottom");
2371   PrintRegionClosure blk(st);
2372   heap_region_iterate(&blk);
2373 }
2374 
2375 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2376   print_on(st);
2377 
2378   // Print the per-region information.
2379   st->cr();
2380   print_regions_on(st);
2381 }
2382 
2383 void G1CollectedHeap::print_on_error(outputStream* st) const {
2384   this->CollectedHeap::print_on_error(st);
2385 
2386   if (_cm != NULL) {
2387     st->cr();
2388     _cm->print_on_error(st);
2389   }
2390 }
2391 
2392 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2393   workers()->threads_do(tc);
2394   tc->do_thread(_cm_thread);
2395   _cm->threads_do(tc);
2396   _cr->threads_do(tc);
2397   tc->do_thread(_service_thread);
2398 }
2399 
2400 void G1CollectedHeap::print_tracing_info() const {
2401   rem_set()->print_summary_info();
2402   concurrent_mark()->print_summary_info();
2403 }
2404 
2405 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2406   return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2407 }
2408 
2409 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2410 
2411   size_t eden_used_bytes = _monitoring_support->eden_space_used();
2412   size_t survivor_used_bytes = _monitoring_support->survivor_space_used();
2413   size_t old_gen_used_bytes = _monitoring_support->old_gen_used();
2414   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2415 
2416   size_t eden_capacity_bytes =
2417     (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2418 
2419   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2420   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, eden_capacity_bytes,
2421                        survivor_used_bytes, old_gen_used_bytes, num_regions());
2422 }
2423 
2424 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2425   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2426                        stats->unused(), stats->used(), stats->region_end_waste(),
2427                        stats->regions_filled(), stats->num_plab_filled(),
2428                        stats->direct_allocated(), stats->num_direct_allocated(),
2429                        stats->failure_used(), stats->failure_waste());
2430 }
2431 
2432 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2433   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2434   gc_tracer->report_gc_heap_summary(when, heap_summary);
2435 
2436   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2437   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2438 }
2439 
2440 void G1CollectedHeap::gc_prologue(bool full) {
2441   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2442 
2443   // Update common counters.
2444   increment_total_collections(full /* full gc */);
2445   if (full || collector_state()->in_concurrent_start_gc()) {
2446     increment_old_marking_cycles_started();
2447   }
2448 }
2449 
2450 void G1CollectedHeap::gc_epilogue(bool full) {
2451   // Update common counters.
2452   if (full) {
2453     // Update the number of full collections that have been completed.
2454     increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2455   }
2456 
2457 #if COMPILER2_OR_JVMCI
2458   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2459 #endif
2460 
2461   // We have just completed a GC. Update the soft reference
2462   // policy with the new heap occupancy
2463   Universe::heap()->update_capacity_and_used_at_gc();
2464 
2465   _collection_pause_end = Ticks::now();
2466 
2467   _free_arena_memory_task->notify_new_stats(&_young_gen_card_set_stats,
2468                                             &_collection_set_candidates_card_set_stats);
2469 }
2470 
2471 uint G1CollectedHeap::uncommit_regions(uint region_limit) {
2472   return _hrm.uncommit_inactive_regions(region_limit);
2473 }
2474 
2475 bool G1CollectedHeap::has_uncommittable_regions() {
2476   return _hrm.has_inactive_regions();
2477 }
2478 
2479 void G1CollectedHeap::uncommit_regions_if_necessary() {
2480   if (has_uncommittable_regions()) {
2481     G1UncommitRegionTask::enqueue();
2482   }
2483 }
2484 
2485 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2486   LogTarget(Trace, gc, heap, verify) lt;
2487 
2488   if (lt.is_enabled()) {
2489     LogStream ls(lt);
2490     // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2491     G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2492     heap_region_iterate(&cl);
2493   }
2494 }
2495 
2496 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2497                                                uint gc_count_before,
2498                                                bool* succeeded,
2499                                                GCCause::Cause gc_cause) {
2500   assert_heap_not_locked_and_not_at_safepoint();
2501   VM_G1CollectForAllocation op(word_size, gc_count_before, gc_cause);
2502   VMThread::execute(&op);
2503 
2504   HeapWord* result = op.result();
2505   bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2506   assert(result == NULL || ret_succeeded,
2507          "the result should be NULL if the VM did not succeed");
2508   *succeeded = ret_succeeded;
2509 
2510   assert_heap_not_locked();
2511   return result;
2512 }
2513 
2514 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) {
2515   assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress");
2516 
2517   MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2518   if (concurrent_operation_is_full_mark) {
2519     _cm->post_concurrent_mark_start();
2520     _cm_thread->start_full_mark();
2521   } else {
2522     _cm->post_concurrent_undo_start();
2523     _cm_thread->start_undo_mark();
2524   }
2525   CGC_lock->notify();
2526 }
2527 
2528 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2529   // We don't nominate objects with many remembered set entries, on
2530   // the assumption that such objects are likely still live.
2531   HeapRegionRemSet* rem_set = r->rem_set();
2532 
2533   return rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold);
2534 }
2535 
2536 #ifndef PRODUCT
2537 void G1CollectedHeap::verify_region_attr_remset_is_tracked() {
2538   class VerifyRegionAttrRemSet : public HeapRegionClosure {
2539   public:
2540     virtual bool do_heap_region(HeapRegion* r) {
2541       G1CollectedHeap* g1h = G1CollectedHeap::heap();
2542       bool const remset_is_tracked = g1h->region_attr(r->bottom()).remset_is_tracked();
2543       assert(r->rem_set()->is_tracked() == remset_is_tracked,
2544              "Region %u remset tracking status (%s) different to region attribute (%s)",
2545              r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(remset_is_tracked));
2546       return false;
2547     }
2548   } cl;
2549   heap_region_iterate(&cl);
2550 }
2551 #endif
2552 
2553 void G1CollectedHeap::start_new_collection_set() {
2554   collection_set()->start_incremental_building();
2555 
2556   clear_region_attr();
2557 
2558   guarantee(_eden.length() == 0, "eden should have been cleared");
2559   policy()->transfer_survivors_to_cset(survivor());
2560 
2561   // We redo the verification but now wrt to the new CSet which
2562   // has just got initialized after the previous CSet was freed.
2563   _cm->verify_no_collection_set_oops();
2564 }
2565 
2566 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2567   if (collector_state()->in_concurrent_start_gc()) {
2568     return G1HeapVerifier::G1VerifyConcurrentStart;
2569   } else if (collector_state()->in_young_only_phase()) {
2570     return G1HeapVerifier::G1VerifyYoungNormal;
2571   } else {
2572     return G1HeapVerifier::G1VerifyMixed;
2573   }
2574 }
2575 
2576 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2577   if (!VerifyBeforeGC) {
2578     return;
2579   }
2580   Ticks start = Ticks::now();
2581   _verifier->prepare_for_verify();
2582   _verifier->verify_region_sets_optional();
2583   _verifier->verify_dirty_young_regions();
2584   _verifier->verify_before_gc(type);
2585   verify_numa_regions("GC Start");
2586   phase_times()->record_verify_before_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2587 }
2588 
2589 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2590   if (!VerifyAfterGC) {
2591     return;
2592   }
2593   Ticks start = Ticks::now();
2594   _verifier->verify_after_gc(type);
2595   verify_numa_regions("GC End");
2596   _verifier->verify_region_sets_optional();
2597   phase_times()->record_verify_after_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2598 }
2599 
2600 void G1CollectedHeap::expand_heap_after_young_collection(){
2601   size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2602   if (expand_bytes > 0) {
2603     // No need for an ergo logging here,
2604     // expansion_amount() does this when it returns a value > 0.
2605     double expand_ms = 0.0;
2606     if (!expand(expand_bytes, _workers, &expand_ms)) {
2607       // We failed to expand the heap. Cannot do anything about it.
2608     }
2609     phase_times()->record_expand_heap_time(expand_ms);
2610   }
2611 }
2612 
2613 bool G1CollectedHeap::do_collection_pause_at_safepoint() {
2614   assert_at_safepoint_on_vm_thread();
2615   guarantee(!is_gc_active(), "collection is not reentrant");
2616 
2617   if (GCLocker::check_active_before_gc()) {
2618     return false;
2619   }
2620 
2621   do_collection_pause_at_safepoint_helper();
2622   return true;
2623 }
2624 
2625 G1HeapPrinterMark::G1HeapPrinterMark(G1CollectedHeap* g1h) : _g1h(g1h), _heap_transition(g1h) {
2626   // This summary needs to be printed before incrementing total collections.
2627   _g1h->rem_set()->print_periodic_summary_info("Before GC RS summary",
2628                                                _g1h->total_collections(),
2629                                                true /* show_thread_times */);
2630   _g1h->print_heap_before_gc();
2631   _g1h->print_heap_regions();
2632 }
2633 
2634 G1HeapPrinterMark::~G1HeapPrinterMark() {
2635   _g1h->policy()->print_age_table();
2636   _g1h->rem_set()->print_coarsen_stats();
2637   // We are at the end of the GC. Total collections has already been increased.
2638   _g1h->rem_set()->print_periodic_summary_info("After GC RS summary",
2639                                                _g1h->total_collections() - 1,
2640                                                false /* show_thread_times */);
2641 
2642   _heap_transition.print();
2643   _g1h->print_heap_regions();
2644   _g1h->print_heap_after_gc();
2645   // Print NUMA statistics.
2646   _g1h->numa()->print_statistics();
2647 }
2648 
2649 G1JFRTracerMark::G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer) :
2650   _timer(timer), _tracer(tracer) {
2651 
2652   _timer->register_gc_start();
2653   _tracer->report_gc_start(G1CollectedHeap::heap()->gc_cause(), _timer->gc_start());
2654   G1CollectedHeap::heap()->trace_heap_before_gc(_tracer);
2655 }
2656 
2657 G1JFRTracerMark::~G1JFRTracerMark() {
2658   G1CollectedHeap::heap()->trace_heap_after_gc(_tracer);
2659   _timer->register_gc_end();
2660   _tracer->report_gc_end(_timer->gc_end(), _timer->time_partitions());
2661 }
2662 
2663 void G1CollectedHeap::prepare_for_mutator_after_young_collection() {
2664   Ticks start = Ticks::now();
2665 
2666   _survivor_evac_stats.adjust_desired_plab_size();
2667   _old_evac_stats.adjust_desired_plab_size();
2668 
2669   // Start a new incremental collection set for the mutator phase.
2670   start_new_collection_set();
2671   _allocator->init_mutator_alloc_regions();
2672 
2673   phase_times()->record_prepare_for_mutator_time_ms((Ticks::now() - start).seconds() * 1000.0);
2674 }
2675 
2676 void G1CollectedHeap::retire_tlabs() {
2677   ensure_parsability(true);
2678 }
2679 
2680 void G1CollectedHeap::do_collection_pause_at_safepoint_helper() {
2681   ResourceMark rm;
2682 
2683   IsGCActiveMark active_gc_mark;
2684   GCIdMark gc_id_mark;
2685   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2686 
2687   GCTraceCPUTime tcpu(_gc_tracer_stw);
2688 
2689   _bytes_used_during_gc = 0;
2690 
2691   policy()->decide_on_concurrent_start_pause();
2692   // Record whether this pause may need to trigger a concurrent operation. Later,
2693   // when we signal the G1ConcurrentMarkThread, the collector state has already
2694   // been reset for the next pause.
2695   bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc();
2696 
2697   // Perform the collection.
2698   G1YoungCollector collector(gc_cause());
2699   collector.collect();
2700 
2701   // It should now be safe to tell the concurrent mark thread to start
2702   // without its logging output interfering with the logging output
2703   // that came from the pause.
2704   if (should_start_concurrent_mark_operation) {
2705     verifier()->verify_bitmap_clear(true /* above_tams_only */);
2706     // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking
2707     // thread(s) could be running concurrently with us. Make sure that anything
2708     // after this point does not assume that we are the only GC thread running.
2709     // Note: of course, the actual marking work will not start until the safepoint
2710     // itself is released in SuspendibleThreadSet::desynchronize().
2711     start_concurrent_cycle(collector.concurrent_operation_is_full_mark());
2712     ConcurrentGCBreakpoints::notify_idle_to_active();
2713   }
2714 }
2715 
2716 void G1CollectedHeap::complete_cleaning(bool class_unloading_occurred) {
2717   uint num_workers = workers()->active_workers();
2718   G1ParallelCleaningTask unlink_task(num_workers, class_unloading_occurred);
2719   workers()->run_task(&unlink_task);
2720 }
2721 
2722 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
2723   assert(obj != NULL, "must not be NULL");
2724   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
2725   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
2726   // may falsely indicate that this is not the case here: however the collection set only
2727   // contains old regions when concurrent mark is not running.
2728   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
2729 }
2730 
2731 void G1CollectedHeap::make_pending_list_reachable() {
2732   if (collector_state()->in_concurrent_start_gc()) {
2733     oop pll_head = Universe::reference_pending_list();
2734     if (pll_head != NULL) {
2735       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
2736       _cm->mark_in_bitmap(0 /* worker_id */, pll_head);
2737     }
2738   }
2739 }
2740 
2741 void G1CollectedHeap::set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates) {
2742   _num_humongous_objects = num_humongous_total;
2743   _num_humongous_reclaim_candidates = num_humongous_candidates;
2744 }
2745 
2746 bool G1CollectedHeap::should_sample_collection_set_candidates() const {
2747   G1CollectionSetCandidates* candidates = G1CollectedHeap::heap()->collection_set()->candidates();
2748   return candidates != NULL && candidates->num_remaining() > 0;
2749 }
2750 
2751 void G1CollectedHeap::set_collection_set_candidates_stats(G1MonotonicArenaMemoryStats& stats) {
2752   _collection_set_candidates_card_set_stats = stats;
2753 }
2754 
2755 void G1CollectedHeap::set_young_gen_card_set_stats(const G1MonotonicArenaMemoryStats& stats) {
2756   _young_gen_card_set_stats = stats;
2757 }
2758 
2759 void G1CollectedHeap::record_obj_copy_mem_stats() {
2760   policy()->old_gen_alloc_tracker()->
2761     add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
2762 
2763   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
2764                                                create_g1_evac_summary(&_old_evac_stats));
2765 }
2766 
2767 void G1CollectedHeap::clear_bitmap_for_region(HeapRegion* hr) {
2768   concurrent_mark()->clear_bitmap_for_region(hr);
2769 }
2770 
2771 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
2772   assert(!hr->is_free(), "the region should not be free");
2773   assert(!hr->is_empty(), "the region should not be empty");
2774   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
2775 
2776   // Reset region metadata to allow reuse.
2777   hr->hr_clear(true /* clear_space */);
2778   _policy->remset_tracker()->update_at_free(hr);
2779 
2780   if (free_list != NULL) {
2781     free_list->add_ordered(hr);
2782   }
2783 }
2784 
2785 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
2786                                             FreeRegionList* free_list) {
2787   assert(hr->is_humongous(), "this is only for humongous regions");
2788   hr->clear_humongous();
2789   free_region(hr, free_list);
2790 }
2791 
2792 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed,
2793                                                const uint archive_regions_removed,
2794                                                const uint humongous_regions_removed) {
2795   if (old_regions_removed > 0 || archive_regions_removed > 0 || humongous_regions_removed > 0) {
2796     MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
2797     _old_set.bulk_remove(old_regions_removed);
2798     _archive_set.bulk_remove(archive_regions_removed);
2799     _humongous_set.bulk_remove(humongous_regions_removed);
2800   }
2801 
2802 }
2803 
2804 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
2805   assert(list != NULL, "list can't be null");
2806   if (!list->is_empty()) {
2807     MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
2808     _hrm.insert_list_into_free_list(list);
2809   }
2810 }
2811 
2812 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
2813   decrease_used(bytes);
2814 }
2815 
2816 void G1CollectedHeap::clear_eden() {
2817   _eden.clear();
2818 }
2819 
2820 void G1CollectedHeap::clear_collection_set() {
2821   collection_set()->clear();
2822 }
2823 
2824 void G1CollectedHeap::rebuild_free_region_list() {
2825   Ticks start = Ticks::now();
2826   _hrm.rebuild_free_list(workers());
2827   phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
2828 }
2829 
2830 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
2831 public:
2832   virtual bool do_heap_region(HeapRegion* r) {
2833     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
2834     G1CollectedHeap::heap()->clear_region_attr(r);
2835     r->clear_young_index_in_cset();
2836     return false;
2837   }
2838 };
2839 
2840 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
2841   G1AbandonCollectionSetClosure cl;
2842   collection_set_iterate_all(&cl);
2843 
2844   collection_set->clear();
2845   collection_set->stop_incremental_building();
2846 }
2847 
2848 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
2849   return _allocator->is_retained_old_region(hr);
2850 }
2851 
2852 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
2853   _eden.add(hr);
2854   _policy->set_region_eden(hr);
2855 }
2856 
2857 #ifdef ASSERT
2858 
2859 class NoYoungRegionsClosure: public HeapRegionClosure {
2860 private:
2861   bool _success;
2862 public:
2863   NoYoungRegionsClosure() : _success(true) { }
2864   bool do_heap_region(HeapRegion* r) {
2865     if (r->is_young()) {
2866       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
2867                             p2i(r->bottom()), p2i(r->end()));
2868       _success = false;
2869     }
2870     return false;
2871   }
2872   bool success() { return _success; }
2873 };
2874 
2875 bool G1CollectedHeap::check_young_list_empty() {
2876   bool ret = (young_regions_count() == 0);
2877 
2878   NoYoungRegionsClosure closure;
2879   heap_region_iterate(&closure);
2880   ret = ret && closure.success();
2881 
2882   return ret;
2883 }
2884 
2885 #endif // ASSERT
2886 
2887 // Remove the given HeapRegion from the appropriate region set.
2888 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) {
2889    if (hr->is_archive()) {
2890     _archive_set.remove(hr);
2891   } else if (hr->is_humongous()) {
2892     _humongous_set.remove(hr);
2893   } else if (hr->is_old()) {
2894     _old_set.remove(hr);
2895   } else if (hr->is_young()) {
2896     // Note that emptying the eden and survivor lists is postponed and instead
2897     // done as the first step when rebuilding the regions sets again. The reason
2898     // for this is that during a full GC string deduplication needs to know if
2899     // a collected region was young or old when the full GC was initiated.
2900     hr->uninstall_surv_rate_group();
2901   } else {
2902     // We ignore free regions, we'll empty the free list afterwards.
2903     assert(hr->is_free(), "it cannot be another type");
2904   }
2905 }
2906 
2907 void G1CollectedHeap::increase_used(size_t bytes) {
2908   _summary_bytes_used += bytes;
2909 }
2910 
2911 void G1CollectedHeap::decrease_used(size_t bytes) {
2912   assert(_summary_bytes_used >= bytes,
2913          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
2914          _summary_bytes_used, bytes);
2915   _summary_bytes_used -= bytes;
2916 }
2917 
2918 void G1CollectedHeap::set_used(size_t bytes) {
2919   _summary_bytes_used = bytes;
2920 }
2921 
2922 class RebuildRegionSetsClosure : public HeapRegionClosure {
2923 private:
2924   bool _free_list_only;
2925 
2926   HeapRegionSet* _old_set;
2927   HeapRegionSet* _archive_set;
2928   HeapRegionSet* _humongous_set;
2929 
2930   HeapRegionManager* _hrm;
2931 
2932   size_t _total_used;
2933 
2934 public:
2935   RebuildRegionSetsClosure(bool free_list_only,
2936                            HeapRegionSet* old_set,
2937                            HeapRegionSet* archive_set,
2938                            HeapRegionSet* humongous_set,
2939                            HeapRegionManager* hrm) :
2940     _free_list_only(free_list_only), _old_set(old_set), _archive_set(archive_set),
2941     _humongous_set(humongous_set), _hrm(hrm), _total_used(0) {
2942     assert(_hrm->num_free_regions() == 0, "pre-condition");
2943     if (!free_list_only) {
2944       assert(_old_set->is_empty(), "pre-condition");
2945       assert(_archive_set->is_empty(), "pre-condition");
2946       assert(_humongous_set->is_empty(), "pre-condition");
2947     }
2948   }
2949 
2950   bool do_heap_region(HeapRegion* r) {
2951     if (r->is_empty()) {
2952       assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
2953       // Add free regions to the free list
2954       r->set_free();
2955       _hrm->insert_into_free_list(r);
2956     } else if (!_free_list_only) {
2957       assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
2958 
2959       if (r->is_humongous()) {
2960         _humongous_set->add(r);
2961       } else if (r->is_archive()) {
2962         _archive_set->add(r);
2963       } else {
2964         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
2965         // We now move all (non-humongous, non-old, non-archive) regions to old gen,
2966         // and register them as such.
2967         r->move_to_old();
2968         _old_set->add(r);
2969       }
2970       _total_used += r->used();
2971     }
2972 
2973     return false;
2974   }
2975 
2976   size_t total_used() {
2977     return _total_used;
2978   }
2979 };
2980 
2981 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
2982   assert_at_safepoint_on_vm_thread();
2983 
2984   if (!free_list_only) {
2985     _eden.clear();
2986     _survivor.clear();
2987   }
2988 
2989   RebuildRegionSetsClosure cl(free_list_only,
2990                               &_old_set, &_archive_set, &_humongous_set,
2991                               &_hrm);
2992   heap_region_iterate(&cl);
2993 
2994   if (!free_list_only) {
2995     set_used(cl.total_used());
2996   }
2997   assert_used_and_recalculate_used_equal(this);
2998 }
2999 
3000 // Methods for the mutator alloc region
3001 
3002 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
3003                                                       bool force,
3004                                                       uint node_index) {
3005   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
3006   bool should_allocate = policy()->should_allocate_mutator_region();
3007   if (force || should_allocate) {
3008     HeapRegion* new_alloc_region = new_region(word_size,
3009                                               HeapRegionType::Eden,
3010                                               false /* do_expand */,
3011                                               node_index);
3012     if (new_alloc_region != NULL) {
3013       set_region_short_lived_locked(new_alloc_region);
3014       _hr_printer.alloc(new_alloc_region, !should_allocate);
3015       _policy->remset_tracker()->update_at_allocate(new_alloc_region);
3016       return new_alloc_region;
3017     }
3018   }
3019   return NULL;
3020 }
3021 
3022 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
3023                                                   size_t allocated_bytes) {
3024   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
3025   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
3026 
3027   collection_set()->add_eden_region(alloc_region);
3028   increase_used(allocated_bytes);
3029   _eden.add_used_bytes(allocated_bytes);
3030   _hr_printer.retire(alloc_region);
3031 
3032   // We update the eden sizes here, when the region is retired,
3033   // instead of when it's allocated, since this is the point that its
3034   // used space has been recorded in _summary_bytes_used.
3035   monitoring_support()->update_eden_size();
3036 }
3037 
3038 // Methods for the GC alloc regions
3039 
3040 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
3041   if (dest.is_old()) {
3042     return true;
3043   } else {
3044     return survivor_regions_count() < policy()->max_survivor_regions();
3045   }
3046 }
3047 
3048 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
3049   assert(FreeList_lock->owned_by_self(), "pre-condition");
3050 
3051   if (!has_more_regions(dest)) {
3052     return NULL;
3053   }
3054 
3055   HeapRegionType type;
3056   if (dest.is_young()) {
3057     type = HeapRegionType::Survivor;
3058   } else {
3059     type = HeapRegionType::Old;
3060   }
3061 
3062   HeapRegion* new_alloc_region = new_region(word_size,
3063                                             type,
3064                                             true /* do_expand */,
3065                                             node_index);
3066 
3067   if (new_alloc_region != NULL) {
3068     if (type.is_survivor()) {
3069       new_alloc_region->set_survivor();
3070       _survivor.add(new_alloc_region);
3071       register_new_survivor_region_with_region_attr(new_alloc_region);
3072     } else {
3073       new_alloc_region->set_old();
3074     }
3075     _policy->remset_tracker()->update_at_allocate(new_alloc_region);
3076     register_region_with_region_attr(new_alloc_region);
3077     _hr_printer.alloc(new_alloc_region);
3078     return new_alloc_region;
3079   }
3080   return NULL;
3081 }
3082 
3083 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
3084                                              size_t allocated_bytes,
3085                                              G1HeapRegionAttr dest) {
3086   _bytes_used_during_gc += allocated_bytes;
3087   if (dest.is_old()) {
3088     old_set_add(alloc_region);
3089   } else {
3090     assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
3091     _survivor.add_used_bytes(allocated_bytes);
3092   }
3093 
3094   bool const during_im = collector_state()->in_concurrent_start_gc();
3095   if (during_im && allocated_bytes > 0) {
3096     _cm->add_root_region(alloc_region);
3097   }
3098   _hr_printer.retire(alloc_region);
3099 }
3100 
3101 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
3102   bool expanded = false;
3103   uint index = _hrm.find_highest_free(&expanded);
3104 
3105   if (index != G1_NO_HRM_INDEX) {
3106     if (expanded) {
3107       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
3108                                 HeapRegion::GrainWords * HeapWordSize);
3109     }
3110     return _hrm.allocate_free_regions_starting_at(index, 1);
3111   }
3112   return NULL;
3113 }
3114 
3115 void G1CollectedHeap::mark_evac_failure_object(uint worker_id, const oop obj, size_t obj_size) const {
3116   assert(!_cm->is_marked_in_bitmap(obj), "must be");
3117 
3118   _cm->raw_mark_in_bitmap(obj);
3119   if (collector_state()->in_concurrent_start_gc()) {
3120     _cm->add_to_liveness(worker_id, obj, obj_size);
3121   }
3122 }
3123 
3124 // Optimized nmethod scanning
3125 class RegisterNMethodOopClosure: public OopClosure {
3126   G1CollectedHeap* _g1h;
3127   nmethod* _nm;
3128 
3129 public:
3130   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3131     _g1h(g1h), _nm(nm) {}
3132 
3133   void do_oop(oop* p) {
3134     oop heap_oop = RawAccess<>::oop_load(p);
3135     if (!CompressedOops::is_null(heap_oop)) {
3136       oop obj = CompressedOops::decode_not_null(heap_oop);
3137       HeapRegion* hr = _g1h->heap_region_containing(obj);
3138       assert(!hr->is_continues_humongous(),
3139              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3140              " starting at " HR_FORMAT,
3141              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3142 
3143       // HeapRegion::add_code_root_locked() avoids adding duplicate entries.
3144       hr->add_code_root_locked(_nm);
3145     }
3146   }
3147 
3148   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3149 };
3150 
3151 class UnregisterNMethodOopClosure: public OopClosure {
3152   G1CollectedHeap* _g1h;
3153   nmethod* _nm;
3154 
3155 public:
3156   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3157     _g1h(g1h), _nm(nm) {}
3158 
3159   void do_oop(oop* p) {
3160     oop heap_oop = RawAccess<>::oop_load(p);
3161     if (!CompressedOops::is_null(heap_oop)) {
3162       oop obj = CompressedOops::decode_not_null(heap_oop);
3163       HeapRegion* hr = _g1h->heap_region_containing(obj);
3164       assert(!hr->is_continues_humongous(),
3165              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3166              " starting at " HR_FORMAT,
3167              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3168 
3169       hr->remove_code_root(_nm);
3170     }
3171   }
3172 
3173   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3174 };
3175 
3176 void G1CollectedHeap::register_nmethod(nmethod* nm) {
3177   guarantee(nm != NULL, "sanity");
3178   RegisterNMethodOopClosure reg_cl(this, nm);
3179   nm->oops_do(&reg_cl);
3180 }
3181 
3182 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
3183   guarantee(nm != NULL, "sanity");
3184   UnregisterNMethodOopClosure reg_cl(this, nm);
3185   nm->oops_do(&reg_cl, true);
3186 }
3187 
3188 void G1CollectedHeap::update_used_after_gc(bool evacuation_failed) {
3189   if (evacuation_failed) {
3190     // Reset the G1EvacuationFailureALot counters and flags
3191     evac_failure_injector()->reset();
3192 
3193     set_used(recalculate_used());
3194   } else {
3195     // The "used" of the collection set have already been subtracted
3196     // when they were freed.  Add in the bytes used.
3197     increase_used(_bytes_used_during_gc);
3198   }
3199 }
3200 
3201 class RebuildCodeRootClosure: public CodeBlobClosure {
3202   G1CollectedHeap* _g1h;
3203 
3204 public:
3205   RebuildCodeRootClosure(G1CollectedHeap* g1h) :
3206     _g1h(g1h) {}
3207 
3208   void do_code_blob(CodeBlob* cb) {
3209     nmethod* nm = cb->as_nmethod_or_null();
3210     if (nm != NULL) {
3211       _g1h->register_nmethod(nm);
3212     }
3213   }
3214 };
3215 
3216 void G1CollectedHeap::rebuild_code_roots() {
3217   RebuildCodeRootClosure blob_cl(this);
3218   CodeCache::blobs_do(&blob_cl);
3219 }
3220 
3221 void G1CollectedHeap::initialize_serviceability() {
3222   _monitoring_support->initialize_serviceability();
3223 }
3224 
3225 MemoryUsage G1CollectedHeap::memory_usage() {
3226   return _monitoring_support->memory_usage();
3227 }
3228 
3229 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
3230   return _monitoring_support->memory_managers();
3231 }
3232 
3233 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
3234   return _monitoring_support->memory_pools();
3235 }
3236 
3237 void G1CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
3238   HeapRegion* region = heap_region_containing(start);
3239   region->fill_with_dummy_object(start, pointer_delta(end, start), zap);
3240 }
3241 
3242 void G1CollectedHeap::start_codecache_marking_cycle_if_inactive(bool concurrent_mark_start) {
3243   // We can reach here with an active code cache marking cycle either because the
3244   // previous G1 concurrent marking cycle was undone (if heap occupancy after the
3245   // concurrent start young collection was below the threshold) or aborted. See
3246   // CodeCache::on_gc_marking_cycle_finish() why this is.  We must not start a new code
3247   // cache cycle then. If we are about to start a new g1 concurrent marking cycle we
3248   // still have to arm all nmethod entry barriers. They are needed for adding oop
3249   // constants to the SATB snapshot. Full GC does not need nmethods to be armed.
3250   if (!CodeCache::is_gc_marking_cycle_active()) {
3251     CodeCache::on_gc_marking_cycle_start();
3252   }
3253   if (concurrent_mark_start) {
3254     CodeCache::arm_all_nmethods();
3255   }
3256 }
3257 
3258 void G1CollectedHeap::finish_codecache_marking_cycle() {
3259   CodeCache::on_gc_marking_cycle_finish();
3260   CodeCache::arm_all_nmethods();
3261 }