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/referenceProcessor.inline.hpp"
  90 #include "gc/shared/suspendibleThreadSet.hpp"
  91 #include "gc/shared/taskqueue.inline.hpp"
  92 #include "gc/shared/taskTerminator.hpp"
  93 #include "gc/shared/tlab_globals.hpp"
  94 #include "gc/shared/workerPolicy.hpp"
  95 #include "gc/shared/weakProcessor.inline.hpp"
  96 #include "logging/log.hpp"
  97 #include "memory/allocation.hpp"
  98 #include "memory/heapInspection.hpp"
  99 #include "memory/iterator.hpp"
 100 #include "memory/metaspaceUtils.hpp"
 101 #include "memory/resourceArea.hpp"
 102 #include "memory/universe.hpp"
 103 #include "oops/access.inline.hpp"
 104 #include "oops/compressedOops.inline.hpp"
 105 #include "oops/oop.inline.hpp"
 106 #include "runtime/atomic.hpp"
 107 #include "runtime/handles.inline.hpp"
 108 #include "runtime/init.hpp"
 109 #include "runtime/java.hpp"
 110 #include "runtime/orderAccess.hpp"
 111 #include "runtime/threadSMR.hpp"
 112 #include "runtime/vmThread.hpp"
 113 #include "utilities/align.hpp"
 114 #include "utilities/autoRestore.hpp"
 115 #include "utilities/bitMap.inline.hpp"
 116 #include "utilities/globalDefinitions.hpp"
 117 #include "utilities/stack.inline.hpp"
 118 
 119 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
 120 
 121 // INVARIANTS/NOTES
 122 //
 123 // All allocation activity covered by the G1CollectedHeap interface is
 124 // serialized by acquiring the HeapLock.  This happens in mem_allocate
 125 // and allocate_new_tlab, which are the "entry" points to the
 126 // allocation code from the rest of the JVM.  (Note that this does not
 127 // apply to TLAB allocation, which is not part of this interface: it
 128 // is done by clients of this interface.)
 129 
 130 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 131   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 132 }
 133 
 134 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 135   // The from card cache is not the memory that is actually committed. So we cannot
 136   // take advantage of the zero_filled parameter.
 137   reset_from_card_cache(start_idx, num_regions);
 138 }
 139 
 140 void G1CollectedHeap::run_batch_task(G1BatchedTask* cl) {
 141   uint num_workers = MAX2(1u, MIN2(cl->num_workers_estimate(), workers()->active_workers()));
 142   cl->set_max_workers(num_workers);
 143   workers()->run_task(cl, num_workers);
 144 }
 145 
 146 uint G1CollectedHeap::get_chunks_per_region() {
 147   uint log_region_size = HeapRegion::LogOfHRGrainBytes;
 148   // Limit the expected input values to current known possible values of the
 149   // (log) region size. Adjust as necessary after testing if changing the permissible
 150   // values for region size.
 151   assert(log_region_size >= 20 && log_region_size <= 29,
 152          "expected value in [20,29], but got %u", log_region_size);
 153   return 1u << (log_region_size / 2 - 4);
 154 }
 155 
 156 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 157                                              MemRegion mr) {
 158   return new HeapRegion(hrs_index, bot(), mr, &_card_set_config);
 159 }
 160 
 161 // Private methods.
 162 
 163 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
 164                                         HeapRegionType type,
 165                                         bool do_expand,
 166                                         uint node_index) {
 167   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 168          "the only time we use this to allocate a humongous region is "
 169          "when we are allocating a single humongous region");
 170 
 171   HeapRegion* res = _hrm.allocate_free_region(type, node_index);
 172 
 173   if (res == nullptr && do_expand) {
 174     // Currently, only attempts to allocate GC alloc regions set
 175     // do_expand to true. So, we should only reach here during a
 176     // safepoint.
 177     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 178 
 179     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 180                               word_size * HeapWordSize);
 181 
 182     assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
 183            "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
 184            word_size * HeapWordSize);
 185     if (expand_single_region(node_index)) {
 186       // Given that expand_single_region() succeeded in expanding the heap, and we
 187       // always expand the heap by an amount aligned to the heap
 188       // region size, the free list should in theory not be empty.
 189       // In either case allocate_free_region() will check for null.
 190       res = _hrm.allocate_free_region(type, node_index);
 191     }
 192   }
 193   return res;
 194 }
 195 
 196 void G1CollectedHeap::set_humongous_metadata(HeapRegion* first_hr,
 197                                              uint num_regions,
 198                                              size_t word_size,
 199                                              bool update_remsets) {
 200   // Calculate the new top of the humongous object.
 201   HeapWord* obj_top = first_hr->bottom() + word_size;
 202   // The word size sum of all the regions used
 203   size_t word_size_sum = num_regions * HeapRegion::GrainWords;
 204   assert(word_size <= word_size_sum, "sanity");
 205 
 206   // How many words memory we "waste" which cannot hold a filler object.
 207   size_t words_not_fillable = 0;
 208 
 209   // Pad out the unused tail of the last region with filler
 210   // objects, for improved usage accounting.
 211 
 212   // How many words can we use for filler objects.
 213   size_t words_fillable = word_size_sum - word_size;
 214 
 215   if (words_fillable >= G1CollectedHeap::min_fill_size()) {
 216     G1CollectedHeap::fill_with_objects(obj_top, words_fillable);
 217   } else {
 218     // We have space to fill, but we cannot fit an object there.
 219     words_not_fillable = words_fillable;
 220     words_fillable = 0;
 221   }
 222 
 223   // We will set up the first region as "starts humongous". This
 224   // will also update the BOT covering all the regions to reflect
 225   // that there is a single object that starts at the bottom of the
 226   // first region.
 227   first_hr->hr_clear(false /* clear_space */);
 228   first_hr->set_starts_humongous(obj_top, words_fillable);
 229 
 230   if (update_remsets) {
 231     _policy->remset_tracker()->update_at_allocate(first_hr);
 232   }
 233 
 234   // Indices of first and last regions in the series.
 235   uint first = first_hr->hrm_index();
 236   uint last = first + num_regions - 1;
 237 
 238   HeapRegion* hr = nullptr;
 239   for (uint i = first + 1; i <= last; ++i) {
 240     hr = region_at(i);
 241     hr->hr_clear(false /* clear_space */);
 242     hr->set_continues_humongous(first_hr);
 243     if (update_remsets) {
 244       _policy->remset_tracker()->update_at_allocate(hr);
 245     }
 246   }
 247 
 248   // Up to this point no concurrent thread would have been able to
 249   // do any scanning on any region in this series. All the top
 250   // fields still point to bottom, so the intersection between
 251   // [bottom,top] and [card_start,card_end] will be empty. Before we
 252   // update the top fields, we'll do a storestore to make sure that
 253   // no thread sees the update to top before the zeroing of the
 254   // object header and the BOT initialization.
 255   OrderAccess::storestore();
 256 
 257   // Now, we will update the top fields of the "continues humongous"
 258   // regions except the last one.
 259   for (uint i = first; i < last; ++i) {
 260     hr = region_at(i);
 261     hr->set_top(hr->end());
 262   }
 263 
 264   hr = region_at(last);
 265   // If we cannot fit a filler object, we must set top to the end
 266   // of the humongous object, otherwise we cannot iterate the heap
 267   // and the BOT will not be complete.
 268   hr->set_top(hr->end() - words_not_fillable);
 269 
 270   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 271          "obj_top should be in last region");
 272 
 273   assert(words_not_fillable == 0 ||
 274          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 275          "Miscalculation in humongous allocation");
 276 }
 277 
 278 HeapWord*
 279 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
 280                                                            uint num_regions,
 281                                                            size_t word_size) {
 282   assert(first_hr != nullptr, "pre-condition");
 283   assert(is_humongous(word_size), "word_size should be humongous");
 284   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 285 
 286   // Index of last region in the series.
 287   uint first = first_hr->hrm_index();
 288   uint last = first + num_regions - 1;
 289 
 290   // We need to initialize the region(s) we just discovered. This is
 291   // a bit tricky given that it can happen concurrently with
 292   // refinement threads refining cards on these regions and
 293   // potentially wanting to refine the BOT as they are scanning
 294   // those cards (this can happen shortly after a cleanup; see CR
 295   // 6991377). So we have to set up the region(s) carefully and in
 296   // a specific order.
 297 
 298   // The passed in hr will be the "starts humongous" region. The header
 299   // of the new object will be placed at the bottom of this region.
 300   HeapWord* new_obj = first_hr->bottom();
 301 
 302   // First, we need to zero the header of the space that we will be
 303   // allocating. When we update top further down, some refinement
 304   // threads might try to scan the region. By zeroing the header we
 305   // ensure that any thread that will try to scan the region will
 306   // come across the zero klass word and bail out.
 307   //
 308   // NOTE: It would not have been correct to have used
 309   // CollectedHeap::fill_with_object() and make the space look like
 310   // an int array. The thread that is doing the allocation will
 311   // later update the object header to a potentially different array
 312   // type and, for a very short period of time, the klass and length
 313   // fields will be inconsistent. This could cause a refinement
 314   // thread to calculate the object size incorrectly.
 315   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 316 
 317   // Next, update the metadata for the regions.
 318   set_humongous_metadata(first_hr, num_regions, word_size, true);
 319 
 320   HeapRegion* last_hr = region_at(last);
 321   size_t used = byte_size(first_hr->bottom(), last_hr->top());
 322 
 323   increase_used(used);
 324 
 325   for (uint i = first; i <= last; ++i) {
 326     HeapRegion *hr = region_at(i);
 327     _humongous_set.add(hr);
 328     _hr_printer.alloc(hr);
 329   }
 330 
 331   return new_obj;
 332 }
 333 
 334 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 335   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 336   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 337 }
 338 
 339 // If could fit into free regions w/o expansion, try.
 340 // Otherwise, if can expand, do so.
 341 // Otherwise, if using ex regions might help, try with ex given back.
 342 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 343   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 344 
 345   _verifier->verify_region_sets_optional();
 346 
 347   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 348 
 349   // Policy: First try to allocate a humongous object in the free list.
 350   HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions);
 351   if (humongous_start == nullptr) {
 352     // Policy: We could not find enough regions for the humongous object in the
 353     // free list. Look through the heap to find a mix of free and uncommitted regions.
 354     // If so, expand the heap and allocate the humongous object.
 355     humongous_start = _hrm.expand_and_allocate_humongous(obj_regions);
 356     if (humongous_start != nullptr) {
 357       // We managed to find a region by expanding the heap.
 358       log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
 359                                 word_size * HeapWordSize);
 360       policy()->record_new_heap_size(num_regions());
 361     } else {
 362       // Policy: Potentially trigger a defragmentation GC.
 363     }
 364   }
 365 
 366   HeapWord* result = nullptr;
 367   if (humongous_start != nullptr) {
 368     result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
 369     assert(result != nullptr, "it should always return a valid result");
 370 
 371     // A successful humongous object allocation changes the used space
 372     // information of the old generation so we need to recalculate the
 373     // sizes and update the jstat counters here.
 374     monitoring_support()->update_sizes();
 375   }
 376 
 377   _verifier->verify_region_sets_optional();
 378 
 379   return result;
 380 }
 381 
 382 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
 383                                              size_t requested_size,
 384                                              size_t* actual_size) {
 385   assert_heap_not_locked_and_not_at_safepoint();
 386   assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
 387 
 388   return attempt_allocation(min_size, requested_size, actual_size);
 389 }
 390 
 391 HeapWord*
 392 G1CollectedHeap::mem_allocate(size_t word_size,
 393                               bool*  gc_overhead_limit_was_exceeded) {
 394   assert_heap_not_locked_and_not_at_safepoint();
 395 
 396   if (is_humongous(word_size)) {
 397     return attempt_allocation_humongous(word_size);
 398   }
 399   size_t dummy = 0;
 400   return attempt_allocation(word_size, word_size, &dummy);
 401 }
 402 
 403 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 404   ResourceMark rm; // For retrieving the thread names in log messages.
 405 
 406   // Make sure you read the note in attempt_allocation_humongous().
 407 
 408   assert_heap_not_locked_and_not_at_safepoint();
 409   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 410          "be called for humongous allocation requests");
 411 
 412   // We should only get here after the first-level allocation attempt
 413   // (attempt_allocation()) failed to allocate.
 414 
 415   // We will loop until a) we manage to successfully perform the
 416   // allocation or b) we successfully schedule a collection which
 417   // fails to perform the allocation. b) is the only case when we'll
 418   // return null.
 419   HeapWord* result = nullptr;
 420   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 421     bool should_try_gc;
 422     uint gc_count_before;
 423 
 424     {
 425       MutexLocker x(Heap_lock);
 426 
 427       // Now that we have the lock, we first retry the allocation in case another
 428       // thread changed the region while we were waiting to acquire the lock.
 429       result = _allocator->attempt_allocation_locked(word_size);
 430       if (result != nullptr) {
 431         return result;
 432       }
 433 
 434       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 435       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 436       // waiting because the GCLocker is active to not wait too long.
 437       if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
 438         // No need for an ergo message here, can_expand_young_list() does this when
 439         // it returns true.
 440         result = _allocator->attempt_allocation_force(word_size);
 441         if (result != nullptr) {
 442           return result;
 443         }
 444       }
 445 
 446       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 447       // the GCLocker initiated GC has been performed and then retry. This includes
 448       // the case when the GC Locker is not active but has not been performed.
 449       should_try_gc = !GCLocker::needs_gc();
 450       // Read the GC count while still holding the Heap_lock.
 451       gc_count_before = total_collections();
 452     }
 453 
 454     if (should_try_gc) {
 455       bool succeeded;
 456       result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_inc_collection_pause);
 457       if (result != nullptr) {
 458         assert(succeeded, "only way to get back a non-null result");
 459         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 460                              Thread::current()->name(), p2i(result));
 461         return result;
 462       }
 463 
 464       if (succeeded) {
 465         // We successfully scheduled a collection which failed to allocate. No
 466         // point in trying to allocate further. We'll just return null.
 467         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 468                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 469         return nullptr;
 470       }
 471       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 472                            Thread::current()->name(), word_size);
 473     } else {
 474       // Failed to schedule a collection.
 475       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 476         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 477                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 478         return nullptr;
 479       }
 480       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 481       // The GCLocker is either active or the GCLocker initiated
 482       // GC has not yet been performed. Stall until it is and
 483       // then retry the allocation.
 484       GCLocker::stall_until_clear();
 485       gclocker_retry_count += 1;
 486     }
 487 
 488     // We can reach here if we were unsuccessful in scheduling a
 489     // collection (because another thread beat us to it) or if we were
 490     // stalled due to the GC locker. In either can we should retry the
 491     // allocation attempt in case another thread successfully
 492     // performed a collection and reclaimed enough space. We do the
 493     // first attempt (without holding the Heap_lock) here and the
 494     // follow-on attempt will be at the start of the next loop
 495     // iteration (after taking the Heap_lock).
 496     size_t dummy = 0;
 497     result = _allocator->attempt_allocation(word_size, word_size, &dummy);
 498     if (result != nullptr) {
 499       return result;
 500     }
 501 
 502     // Give a warning if we seem to be looping forever.
 503     if ((QueuedAllocationWarningCount > 0) &&
 504         (try_count % QueuedAllocationWarningCount == 0)) {
 505       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 506                              Thread::current()->name(), try_count, word_size);
 507     }
 508   }
 509 
 510   ShouldNotReachHere();
 511   return nullptr;
 512 }
 513 
 514 template <typename Func>
 515 void G1CollectedHeap::iterate_regions_in_range(MemRegion range, const Func& func) {
 516   // Mark each G1 region touched by the range as old, add it to
 517   // the old set, and set top.
 518   HeapRegion* curr_region = _hrm.addr_to_region(range.start());
 519   HeapRegion* end_region = _hrm.addr_to_region(range.last());
 520 
 521   while (curr_region != nullptr) {
 522     bool is_last = curr_region == end_region;
 523     HeapRegion* next_region = is_last ? nullptr : _hrm.next_region_in_heap(curr_region);
 524 
 525     func(curr_region, is_last);
 526 
 527     curr_region = next_region;
 528   }
 529 }
 530 
 531 HeapWord* G1CollectedHeap::alloc_archive_region(size_t word_size, HeapWord* preferred_addr) {
 532   assert(!is_init_completed(), "Expect to be called at JVM init time");
 533   MutexLocker x(Heap_lock);
 534 
 535   MemRegion reserved = _hrm.reserved();
 536 
 537   if (reserved.word_size() <= word_size) {
 538     log_info(gc, heap)("Unable to allocate regions as archive heap is too large; size requested = " SIZE_FORMAT
 539                        " bytes, heap = " SIZE_FORMAT " bytes", word_size, reserved.word_size());
 540     return nullptr;
 541   }
 542 
 543   // Temporarily disable pretouching of heap pages. This interface is used
 544   // when mmap'ing archived heap data in, so pre-touching is wasted.
 545   FlagSetting fs(AlwaysPreTouch, false);
 546 
 547   size_t commits = 0;
 548   // Attempt to allocate towards the end of the heap.
 549   HeapWord* start_addr = reserved.end() - align_up(word_size, HeapRegion::GrainWords);
 550   MemRegion range = MemRegion(start_addr, word_size);
 551   HeapWord* last_address = range.last();
 552   if (!_hrm.allocate_containing_regions(range, &commits, workers())) {
 553     return nullptr;
 554   }
 555   increase_used(word_size * HeapWordSize);
 556   if (commits != 0) {
 557     log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 558                               HeapRegion::GrainWords * HeapWordSize * commits);
 559   }
 560 
 561   // Mark each G1 region touched by the range as old, add it to
 562   // the old set, and set top.
 563   auto set_region_to_old = [&] (HeapRegion* r, bool is_last) {
 564     assert(r->is_empty(), "Region already in use (%u)", r->hrm_index());
 565 
 566     HeapWord* top = is_last ? last_address + 1 : r->end();
 567     r->set_top(top);
 568 
 569     r->set_old();
 570     _hr_printer.alloc(r);
 571     _old_set.add(r);
 572   };
 573 
 574   iterate_regions_in_range(range, set_region_to_old);
 575   return start_addr;
 576 }
 577 
 578 void G1CollectedHeap::populate_archive_regions_bot_part(MemRegion range) {
 579   assert(!is_init_completed(), "Expect to be called at JVM init time");
 580 
 581   iterate_regions_in_range(range,
 582                            [&] (HeapRegion* r, bool is_last) {
 583                              r->update_bot();
 584                            });
 585 }
 586 
 587 void G1CollectedHeap::dealloc_archive_regions(MemRegion range) {
 588   assert(!is_init_completed(), "Expect to be called at JVM init time");
 589   MemRegion reserved = _hrm.reserved();
 590   size_t size_used = 0;
 591   uint shrink_count = 0;
 592 
 593   // Free the G1 regions that are within the specified range.
 594   MutexLocker x(Heap_lock);
 595   HeapWord* start_address = range.start();
 596   HeapWord* last_address = range.last();
 597 
 598   assert(reserved.contains(start_address) && reserved.contains(last_address),
 599          "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 600          p2i(start_address), p2i(last_address));
 601   size_used += range.byte_size();
 602 
 603   // Free, empty and uncommit regions with CDS archive content.
 604   auto dealloc_archive_region = [&] (HeapRegion* r, bool is_last) {
 605     guarantee(r->is_old(), "Expected old region at index %u", r->hrm_index());
 606     _old_set.remove(r);
 607     r->set_free();
 608     r->set_top(r->bottom());
 609     _hrm.shrink_at(r->hrm_index(), 1);
 610     shrink_count++;
 611   };
 612 
 613   iterate_regions_in_range(range, dealloc_archive_region);
 614 
 615   if (shrink_count != 0) {
 616     log_debug(gc, ergo, heap)("Attempt heap shrinking (CDS archive regions). Total size: " SIZE_FORMAT "B",
 617                               HeapRegion::GrainWords * HeapWordSize * shrink_count);
 618     // Explicit uncommit.
 619     uncommit_regions(shrink_count);
 620   }
 621   decrease_used(size_used);
 622 }
 623 
 624 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
 625                                                      size_t desired_word_size,
 626                                                      size_t* actual_word_size) {
 627   assert_heap_not_locked_and_not_at_safepoint();
 628   assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
 629          "be called for humongous allocation requests");
 630 
 631   HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
 632 
 633   if (result == nullptr) {
 634     *actual_word_size = desired_word_size;
 635     result = attempt_allocation_slow(desired_word_size);
 636   }
 637 
 638   assert_heap_not_locked();
 639   if (result != nullptr) {
 640     assert(*actual_word_size != 0, "Actual size must have been set here");
 641     dirty_young_block(result, *actual_word_size);
 642   } else {
 643     *actual_word_size = 0;
 644   }
 645 
 646   return result;
 647 }
 648 
 649 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 650   ResourceMark rm; // For retrieving the thread names in log messages.
 651 
 652   // The structure of this method has a lot of similarities to
 653   // attempt_allocation_slow(). The reason these two were not merged
 654   // into a single one is that such a method would require several "if
 655   // allocation is not humongous do this, otherwise do that"
 656   // conditional paths which would obscure its flow. In fact, an early
 657   // version of this code did use a unified method which was harder to
 658   // follow and, as a result, it had subtle bugs that were hard to
 659   // track down. So keeping these two methods separate allows each to
 660   // be more readable. It will be good to keep these two in sync as
 661   // much as possible.
 662 
 663   assert_heap_not_locked_and_not_at_safepoint();
 664   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 665          "should only be called for humongous allocations");
 666 
 667   // Humongous objects can exhaust the heap quickly, so we should check if we
 668   // need to start a marking cycle at each humongous object allocation. We do
 669   // the check before we do the actual allocation. The reason for doing it
 670   // before the allocation is that we avoid having to keep track of the newly
 671   // allocated memory while we do a GC.
 672   if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
 673                                         word_size)) {
 674     collect(GCCause::_g1_humongous_allocation);
 675   }
 676 
 677   // We will loop until a) we manage to successfully perform the
 678   // allocation or b) we successfully schedule a collection which
 679   // fails to perform the allocation. b) is the only case when we'll
 680   // return null.
 681   HeapWord* result = nullptr;
 682   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 683     bool should_try_gc;
 684     uint gc_count_before;
 685 
 686 
 687     {
 688       MutexLocker x(Heap_lock);
 689 
 690       size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 691       // Given that humongous objects are not allocated in young
 692       // regions, we'll first try to do the allocation without doing a
 693       // collection hoping that there's enough space in the heap.
 694       result = humongous_obj_allocate(word_size);
 695       if (result != nullptr) {
 696         policy()->old_gen_alloc_tracker()->
 697           add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 698         return result;
 699       }
 700 
 701       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 702       // the GCLocker initiated GC has been performed and then retry. This includes
 703       // the case when the GC Locker is not active but has not been performed.
 704       should_try_gc = !GCLocker::needs_gc();
 705       // Read the GC count while still holding the Heap_lock.
 706       gc_count_before = total_collections();
 707     }
 708 
 709     if (should_try_gc) {
 710       bool succeeded;
 711       result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_humongous_allocation);
 712       if (result != nullptr) {
 713         assert(succeeded, "only way to get back a non-null result");
 714         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 715                              Thread::current()->name(), p2i(result));
 716         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 717         policy()->old_gen_alloc_tracker()->
 718           record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
 719         return result;
 720       }
 721 
 722       if (succeeded) {
 723         // We successfully scheduled a collection which failed to allocate. No
 724         // point in trying to allocate further. We'll just return null.
 725         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 726                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 727         return nullptr;
 728       }
 729       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 730                            Thread::current()->name(), word_size);
 731     } else {
 732       // Failed to schedule a collection.
 733       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 734         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 735                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 736         return nullptr;
 737       }
 738       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 739       // The GCLocker is either active or the GCLocker initiated
 740       // GC has not yet been performed. Stall until it is and
 741       // then retry the allocation.
 742       GCLocker::stall_until_clear();
 743       gclocker_retry_count += 1;
 744     }
 745 
 746 
 747     // We can reach here if we were unsuccessful in scheduling a
 748     // collection (because another thread beat us to it) or if we were
 749     // stalled due to the GC locker. In either can we should retry the
 750     // allocation attempt in case another thread successfully
 751     // performed a collection and reclaimed enough space.
 752     // Humongous object allocation always needs a lock, so we wait for the retry
 753     // in the next iteration of the loop, unlike for the regular iteration case.
 754     // Give a warning if we seem to be looping forever.
 755 
 756     if ((QueuedAllocationWarningCount > 0) &&
 757         (try_count % QueuedAllocationWarningCount == 0)) {
 758       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 759                              Thread::current()->name(), try_count, word_size);
 760     }
 761   }
 762 
 763   ShouldNotReachHere();
 764   return nullptr;
 765 }
 766 
 767 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 768                                                            bool expect_null_mutator_alloc_region) {
 769   assert_at_safepoint_on_vm_thread();
 770   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 771          "the current alloc region was unexpectedly found to be non-null");
 772 
 773   if (!is_humongous(word_size)) {
 774     return _allocator->attempt_allocation_locked(word_size);
 775   } else {
 776     HeapWord* result = humongous_obj_allocate(word_size);
 777     if (result != nullptr && policy()->need_to_start_conc_mark("STW humongous allocation")) {
 778       collector_state()->set_initiate_conc_mark_if_possible(true);
 779     }
 780     return result;
 781   }
 782 
 783   ShouldNotReachHere();
 784 }
 785 
 786 class PostCompactionPrinterClosure: public HeapRegionClosure {
 787 private:
 788   G1HRPrinter* _hr_printer;
 789 public:
 790   bool do_heap_region(HeapRegion* hr) {
 791     assert(!hr->is_young(), "not expecting to find young regions");
 792     _hr_printer->post_compaction(hr);
 793     return false;
 794   }
 795 
 796   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 797     : _hr_printer(hr_printer) { }
 798 };
 799 
 800 void G1CollectedHeap::print_heap_after_full_collection() {
 801   // Post collection region logging.
 802   // We should do this after we potentially resize the heap so
 803   // that all the COMMIT / UNCOMMIT events are generated before
 804   // the compaction events.
 805   if (_hr_printer.is_active()) {
 806     PostCompactionPrinterClosure cl(hr_printer());
 807     heap_region_iterate(&cl);
 808   }
 809 }
 810 
 811 bool G1CollectedHeap::abort_concurrent_cycle() {
 812   // Disable discovery and empty the discovered lists
 813   // for the CM ref processor.
 814   _ref_processor_cm->disable_discovery();
 815   _ref_processor_cm->abandon_partial_discovery();
 816   _ref_processor_cm->verify_no_references_recorded();
 817 
 818   // Abandon current iterations of concurrent marking and concurrent
 819   // refinement, if any are in progress.
 820   return concurrent_mark()->concurrent_cycle_abort();
 821 }
 822 
 823 void G1CollectedHeap::prepare_heap_for_full_collection() {
 824   // Make sure we'll choose a new allocation region afterwards.
 825   _allocator->release_mutator_alloc_regions();
 826   _allocator->abandon_gc_alloc_regions();
 827 
 828   // We may have added regions to the current incremental collection
 829   // set between the last GC or pause and now. We need to clear the
 830   // incremental collection set and then start rebuilding it afresh
 831   // after this full GC.
 832   abandon_collection_set(collection_set());
 833 
 834   _hrm.remove_all_free_regions();
 835 }
 836 
 837 void G1CollectedHeap::verify_before_full_collection() {
 838   assert_used_and_recalculate_used_equal(this);
 839   if (!VerifyBeforeGC) {
 840     return;
 841   }
 842   if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) {
 843     return;
 844   }
 845   _verifier->verify_region_sets_optional();
 846   _verifier->verify_before_gc();
 847   _verifier->verify_bitmap_clear(true /* above_tams_only */);
 848 }
 849 
 850 void G1CollectedHeap::prepare_for_mutator_after_full_collection() {
 851   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
 852   ClassLoaderDataGraph::purge(/*at_safepoint*/true);
 853   DEBUG_ONLY(MetaspaceUtils::verify();)
 854 
 855   // Prepare heap for normal collections.
 856   assert(num_free_regions() == 0, "we should not have added any free regions");
 857   rebuild_region_sets(false /* free_list_only */);
 858   abort_refinement();
 859   resize_heap_if_necessary();
 860   uncommit_regions_if_necessary();
 861 
 862   // Rebuild the code root lists for each region
 863   rebuild_code_roots();
 864 
 865   start_new_collection_set();
 866   _allocator->init_mutator_alloc_regions();
 867 
 868   // Post collection state updates.
 869   MetaspaceGC::compute_new_size();
 870 }
 871 
 872 void G1CollectedHeap::abort_refinement() {
 873   // Discard all remembered set updates and reset refinement statistics.
 874   G1BarrierSet::dirty_card_queue_set().abandon_logs_and_stats();
 875   assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
 876          "DCQS should be empty");
 877   concurrent_refine()->get_and_reset_refinement_stats();
 878 }
 879 
 880 void G1CollectedHeap::verify_after_full_collection() {
 881   if (!VerifyAfterGC) {
 882     return;
 883   }
 884   if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) {
 885     return;
 886   }
 887   _hrm.verify_optional();
 888   _verifier->verify_region_sets_optional();
 889   _verifier->verify_after_gc();
 890   _verifier->verify_bitmap_clear(false /* above_tams_only */);
 891 
 892   // At this point there should be no regions in the
 893   // entire heap tagged as young.
 894   assert(check_young_list_empty(), "young list should be empty at this point");
 895 
 896   // Note: since we've just done a full GC, concurrent
 897   // marking is no longer active. Therefore we need not
 898   // re-enable reference discovery for the CM ref processor.
 899   // That will be done at the start of the next marking cycle.
 900   // We also know that the STW processor should no longer
 901   // discover any new references.
 902   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
 903   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
 904   _ref_processor_stw->verify_no_references_recorded();
 905   _ref_processor_cm->verify_no_references_recorded();
 906 }
 907 
 908 bool G1CollectedHeap::do_full_collection(bool clear_all_soft_refs,
 909                                          bool do_maximal_compaction) {
 910   assert_at_safepoint_on_vm_thread();
 911 
 912   if (GCLocker::check_active_before_gc()) {
 913     // Full GC was not completed.
 914     return false;
 915   }
 916 
 917   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
 918       soft_ref_policy()->should_clear_all_soft_refs();
 919 
 920   G1FullGCMark gc_mark;
 921   GCTraceTime(Info, gc) tm("Pause Full", nullptr, gc_cause(), true);
 922   G1FullCollector collector(this, do_clear_all_soft_refs, do_maximal_compaction, gc_mark.tracer());
 923 
 924   collector.prepare_collection();
 925   collector.collect();
 926   collector.complete_collection();
 927 
 928   // Full collection was successfully completed.
 929   return true;
 930 }
 931 
 932 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
 933   // Currently, there is no facility in the do_full_collection(bool) API to notify
 934   // the caller that the collection did not succeed (e.g., because it was locked
 935   // out by the GC locker). So, right now, we'll ignore the return value.
 936 
 937   do_full_collection(clear_all_soft_refs,
 938                      false /* do_maximal_compaction */);
 939 }
 940 
 941 bool G1CollectedHeap::upgrade_to_full_collection() {
 942   GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
 943   log_info(gc, ergo)("Attempting full compaction clearing soft references");
 944   bool success = do_full_collection(true  /* clear_all_soft_refs */,
 945                                     false /* do_maximal_compaction */);
 946   // do_full_collection only fails if blocked by GC locker and that can't
 947   // be the case here since we only call this when already completed one gc.
 948   assert(success, "invariant");
 949   return success;
 950 }
 951 
 952 void G1CollectedHeap::resize_heap_if_necessary() {
 953   assert_at_safepoint_on_vm_thread();
 954 
 955   bool should_expand;
 956   size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
 957 
 958   if (resize_amount == 0) {
 959     return;
 960   } else if (should_expand) {
 961     expand(resize_amount, _workers);
 962   } else {
 963     shrink(resize_amount);
 964   }
 965 }
 966 
 967 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
 968                                                             bool do_gc,
 969                                                             bool maximal_compaction,
 970                                                             bool expect_null_mutator_alloc_region,
 971                                                             bool* gc_succeeded) {
 972   *gc_succeeded = true;
 973   // Let's attempt the allocation first.
 974   HeapWord* result =
 975     attempt_allocation_at_safepoint(word_size,
 976                                     expect_null_mutator_alloc_region);
 977   if (result != nullptr) {
 978     return result;
 979   }
 980 
 981   // In a G1 heap, we're supposed to keep allocation from failing by
 982   // incremental pauses.  Therefore, at least for now, we'll favor
 983   // expansion over collection.  (This might change in the future if we can
 984   // do something smarter than full collection to satisfy a failed alloc.)
 985   result = expand_and_allocate(word_size);
 986   if (result != nullptr) {
 987     return result;
 988   }
 989 
 990   if (do_gc) {
 991     GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
 992     // Expansion didn't work, we'll try to do a Full GC.
 993     // If maximal_compaction is set we clear all soft references and don't
 994     // allow any dead wood to be left on the heap.
 995     if (maximal_compaction) {
 996       log_info(gc, ergo)("Attempting maximal full compaction clearing soft references");
 997     } else {
 998       log_info(gc, ergo)("Attempting full compaction");
 999     }
1000     *gc_succeeded = do_full_collection(maximal_compaction /* clear_all_soft_refs */ ,
1001                                        maximal_compaction /* do_maximal_compaction */);
1002   }
1003 
1004   return nullptr;
1005 }
1006 
1007 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1008                                                      bool* succeeded) {
1009   assert_at_safepoint_on_vm_thread();
1010 
1011   // Attempts to allocate followed by Full GC.
1012   HeapWord* result =
1013     satisfy_failed_allocation_helper(word_size,
1014                                      true,  /* do_gc */
1015                                      false, /* maximum_collection */
1016                                      false, /* expect_null_mutator_alloc_region */
1017                                      succeeded);
1018 
1019   if (result != nullptr || !*succeeded) {
1020     return result;
1021   }
1022 
1023   // Attempts to allocate followed by Full GC that will collect all soft references.
1024   result = satisfy_failed_allocation_helper(word_size,
1025                                             true, /* do_gc */
1026                                             true, /* maximum_collection */
1027                                             true, /* expect_null_mutator_alloc_region */
1028                                             succeeded);
1029 
1030   if (result != nullptr || !*succeeded) {
1031     return result;
1032   }
1033 
1034   // Attempts to allocate, no GC
1035   result = satisfy_failed_allocation_helper(word_size,
1036                                             false, /* do_gc */
1037                                             false, /* maximum_collection */
1038                                             true,  /* expect_null_mutator_alloc_region */
1039                                             succeeded);
1040 
1041   if (result != nullptr) {
1042     return result;
1043   }
1044 
1045   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1046          "Flag should have been handled and cleared prior to this point");
1047 
1048   // What else?  We might try synchronous finalization later.  If the total
1049   // space available is large enough for the allocation, then a more
1050   // complete compaction phase than we've tried so far might be
1051   // appropriate.
1052   return nullptr;
1053 }
1054 
1055 // Attempting to expand the heap sufficiently
1056 // to support an allocation of the given "word_size".  If
1057 // successful, perform the allocation and return the address of the
1058 // allocated block, or else null.
1059 
1060 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1061   assert_at_safepoint_on_vm_thread();
1062 
1063   _verifier->verify_region_sets_optional();
1064 
1065   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1066   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1067                             word_size * HeapWordSize);
1068 
1069 
1070   if (expand(expand_bytes, _workers)) {
1071     _hrm.verify_optional();
1072     _verifier->verify_region_sets_optional();
1073     return attempt_allocation_at_safepoint(word_size,
1074                                            false /* expect_null_mutator_alloc_region */);
1075   }
1076   return nullptr;
1077 }
1078 
1079 bool G1CollectedHeap::expand(size_t expand_bytes, WorkerThreads* pretouch_workers, double* expand_time_ms) {
1080   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1081   aligned_expand_bytes = align_up(aligned_expand_bytes,
1082                                        HeapRegion::GrainBytes);
1083 
1084   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1085                             expand_bytes, aligned_expand_bytes);
1086 
1087   if (is_maximal_no_gc()) {
1088     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1089     return false;
1090   }
1091 
1092   double expand_heap_start_time_sec = os::elapsedTime();
1093   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1094   assert(regions_to_expand > 0, "Must expand by at least one region");
1095 
1096   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1097   if (expand_time_ms != nullptr) {
1098     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1099   }
1100 
1101   assert(expanded_by > 0, "must have failed during commit.");
1102 
1103   size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1104   assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1105   policy()->record_new_heap_size(num_regions());
1106 
1107   return true;
1108 }
1109 
1110 bool G1CollectedHeap::expand_single_region(uint node_index) {
1111   uint expanded_by = _hrm.expand_on_preferred_node(node_index);
1112 
1113   if (expanded_by == 0) {
1114     assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available());
1115     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1116     return false;
1117   }
1118 
1119   policy()->record_new_heap_size(num_regions());
1120   return true;
1121 }
1122 
1123 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1124   size_t aligned_shrink_bytes =
1125     ReservedSpace::page_align_size_down(shrink_bytes);
1126   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1127                                          HeapRegion::GrainBytes);
1128   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1129 
1130   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1131   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1132 
1133   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",
1134                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1135   if (num_regions_removed > 0) {
1136     log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed);
1137     policy()->record_new_heap_size(num_regions());
1138   } else {
1139     log_debug(gc, ergo, heap)("Did not shrink the heap (heap shrinking operation failed)");
1140   }
1141 }
1142 
1143 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1144   _verifier->verify_region_sets_optional();
1145 
1146   // We should only reach here at the end of a Full GC or during Remark which
1147   // means we should not not be holding to any GC alloc regions. The method
1148   // below will make sure of that and do any remaining clean up.
1149   _allocator->abandon_gc_alloc_regions();
1150 
1151   // Instead of tearing down / rebuilding the free lists here, we
1152   // could instead use the remove_all_pending() method on free_list to
1153   // remove only the ones that we need to remove.
1154   _hrm.remove_all_free_regions();
1155   shrink_helper(shrink_bytes);
1156   rebuild_region_sets(true /* free_list_only */);
1157 
1158   _hrm.verify_optional();
1159   _verifier->verify_region_sets_optional();
1160 }
1161 
1162 class OldRegionSetChecker : public HeapRegionSetChecker {
1163 public:
1164   void check_mt_safety() {
1165     // Master Old Set MT safety protocol:
1166     // (a) If we're at a safepoint, operations on the master old set
1167     // should be invoked:
1168     // - by the VM thread (which will serialize them), or
1169     // - by the GC workers while holding the FreeList_lock, if we're
1170     //   at a safepoint for an evacuation pause (this lock is taken
1171     //   anyway when an GC alloc region is retired so that a new one
1172     //   is allocated from the free list), or
1173     // - by the GC workers while holding the OldSets_lock, if we're at a
1174     //   safepoint for a cleanup pause.
1175     // (b) If we're not at a safepoint, operations on the master old set
1176     // should be invoked while holding the Heap_lock.
1177 
1178     if (SafepointSynchronize::is_at_safepoint()) {
1179       guarantee(Thread::current()->is_VM_thread() ||
1180                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1181                 "master old set MT safety protocol at a safepoint");
1182     } else {
1183       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1184     }
1185   }
1186   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1187   const char* get_description() { return "Old Regions"; }
1188 };
1189 
1190 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1191 public:
1192   void check_mt_safety() {
1193     // Humongous Set MT safety protocol:
1194     // (a) If we're at a safepoint, operations on the master humongous
1195     // set should be invoked by either the VM thread (which will
1196     // serialize them) or by the GC workers while holding the
1197     // OldSets_lock.
1198     // (b) If we're not at a safepoint, operations on the master
1199     // humongous set should be invoked while holding the Heap_lock.
1200 
1201     if (SafepointSynchronize::is_at_safepoint()) {
1202       guarantee(Thread::current()->is_VM_thread() ||
1203                 OldSets_lock->owned_by_self(),
1204                 "master humongous set MT safety protocol at a safepoint");
1205     } else {
1206       guarantee(Heap_lock->owned_by_self(),
1207                 "master humongous set MT safety protocol outside a safepoint");
1208     }
1209   }
1210   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1211   const char* get_description() { return "Humongous Regions"; }
1212 };
1213 
1214 G1CollectedHeap::G1CollectedHeap() :
1215   CollectedHeap(),
1216   _service_thread(nullptr),
1217   _periodic_gc_task(nullptr),
1218   _free_arena_memory_task(nullptr),
1219   _workers(nullptr),
1220   _card_table(nullptr),
1221   _collection_pause_end(Ticks::now()),
1222   _soft_ref_policy(),
1223   _old_set("Old Region Set", new OldRegionSetChecker()),
1224   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1225   _bot(nullptr),
1226   _listener(),
1227   _numa(G1NUMA::create()),
1228   _hrm(),
1229   _allocator(nullptr),
1230   _evac_failure_injector(),
1231   _verifier(nullptr),
1232   _summary_bytes_used(0),
1233   _bytes_used_during_gc(0),
1234   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1235   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1236   _monitoring_support(nullptr),
1237   _num_humongous_objects(0),
1238   _num_humongous_reclaim_candidates(0),
1239   _hr_printer(),
1240   _collector_state(),
1241   _old_marking_cycles_started(0),
1242   _old_marking_cycles_completed(0),
1243   _eden(),
1244   _survivor(),
1245   _gc_timer_stw(new STWGCTimer()),
1246   _gc_tracer_stw(new G1NewTracer()),
1247   _policy(new G1Policy(_gc_timer_stw)),
1248   _heap_sizing_policy(nullptr),
1249   _collection_set(this, _policy),
1250   _rem_set(nullptr),
1251   _card_set_config(),
1252   _card_set_freelist_pool(G1CardSetConfiguration::num_mem_object_types()),
1253   _cm(nullptr),
1254   _cm_thread(nullptr),
1255   _cr(nullptr),
1256   _task_queues(nullptr),
1257   _ref_processor_stw(nullptr),
1258   _is_alive_closure_stw(this),
1259   _is_subject_to_discovery_stw(this),
1260   _ref_processor_cm(nullptr),
1261   _is_alive_closure_cm(this),
1262   _is_subject_to_discovery_cm(this),
1263   _region_attr() {
1264 
1265   _verifier = new G1HeapVerifier(this);
1266 
1267   _allocator = new G1Allocator(this);
1268 
1269   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1270 
1271   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1272 
1273   // Override the default _filler_array_max_size so that no humongous filler
1274   // objects are created.
1275   _filler_array_max_size = _humongous_object_threshold_in_words;
1276 
1277   // Override the default _stack_chunk_max_size so that no humongous stack chunks are created
1278   _stack_chunk_max_size = _humongous_object_threshold_in_words;
1279 
1280   uint n_queues = ParallelGCThreads;
1281   _task_queues = new G1ScannerTasksQueueSet(n_queues);
1282 
1283   for (uint i = 0; i < n_queues; i++) {
1284     G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1285     _task_queues->register_queue(i, q);
1286   }
1287 
1288   _gc_tracer_stw->initialize();
1289 
1290   guarantee(_task_queues != nullptr, "task_queues allocation failure.");
1291 }
1292 
1293 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1294                                                                  size_t size,
1295                                                                  size_t translation_factor) {
1296   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1297   // Allocate a new reserved space, preferring to use large pages.
1298   ReservedSpace rs(size, preferred_page_size);
1299   size_t page_size = rs.page_size();
1300   G1RegionToSpaceMapper* result  =
1301     G1RegionToSpaceMapper::create_mapper(rs,
1302                                          size,
1303                                          page_size,
1304                                          HeapRegion::GrainBytes,
1305                                          translation_factor,
1306                                          mtGC);
1307 
1308   os::trace_page_sizes_for_requested_size(description,
1309                                           size,
1310                                           preferred_page_size,
1311                                           rs.base(),
1312                                           rs.size(),
1313                                           page_size);
1314 
1315   return result;
1316 }
1317 
1318 jint G1CollectedHeap::initialize_concurrent_refinement() {
1319   jint ecode = JNI_OK;
1320   _cr = G1ConcurrentRefine::create(policy(), &ecode);
1321   return ecode;
1322 }
1323 
1324 jint G1CollectedHeap::initialize_service_thread() {
1325   _service_thread = new G1ServiceThread();
1326   if (_service_thread->osthread() == nullptr) {
1327     vm_shutdown_during_initialization("Could not create G1ServiceThread");
1328     return JNI_ENOMEM;
1329   }
1330   return JNI_OK;
1331 }
1332 
1333 jint G1CollectedHeap::initialize() {
1334 
1335   // Necessary to satisfy locking discipline assertions.
1336 
1337   MutexLocker x(Heap_lock);
1338 
1339   // While there are no constraints in the GC code that HeapWordSize
1340   // be any particular value, there are multiple other areas in the
1341   // system which believe this to be true (e.g. oop->object_size in some
1342   // cases incorrectly returns the size in wordSize units rather than
1343   // HeapWordSize).
1344   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1345 
1346   size_t init_byte_size = InitialHeapSize;
1347   size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1348 
1349   // Ensure that the sizes are properly aligned.
1350   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1351   Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1352   Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1353 
1354   // Reserve the maximum.
1355 
1356   // When compressed oops are enabled, the preferred heap base
1357   // is calculated by subtracting the requested size from the
1358   // 32Gb boundary and using the result as the base address for
1359   // heap reservation. If the requested size is not aligned to
1360   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1361   // into the ReservedHeapSpace constructor) then the actual
1362   // base of the reserved heap may end up differing from the
1363   // address that was requested (i.e. the preferred heap base).
1364   // If this happens then we could end up using a non-optimal
1365   // compressed oops mode.
1366 
1367   ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1368                                                      HeapAlignment);
1369 
1370   initialize_reserved_region(heap_rs);
1371 
1372   // Create the barrier set for the entire reserved region.
1373   G1CardTable* ct = new G1CardTable(heap_rs.region());
1374   G1BarrierSet* bs = new G1BarrierSet(ct);
1375   bs->initialize();
1376   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1377   BarrierSet::set_barrier_set(bs);
1378   _card_table = ct;
1379 
1380   {
1381     G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1382     satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1383     satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1384   }
1385 
1386   // Create space mappers.
1387   size_t page_size = heap_rs.page_size();
1388   G1RegionToSpaceMapper* heap_storage =
1389     G1RegionToSpaceMapper::create_mapper(heap_rs,
1390                                          heap_rs.size(),
1391                                          page_size,
1392                                          HeapRegion::GrainBytes,
1393                                          1,
1394                                          mtJavaHeap);
1395   if(heap_storage == nullptr) {
1396     vm_shutdown_during_initialization("Could not initialize G1 heap");
1397     return JNI_ERR;
1398   }
1399 
1400   os::trace_page_sizes("Heap",
1401                        MinHeapSize,
1402                        reserved_byte_size,
1403                        heap_rs.base(),
1404                        heap_rs.size(),
1405                        page_size);
1406   heap_storage->set_mapping_changed_listener(&_listener);
1407 
1408   // Create storage for the BOT, card table and the bitmap.
1409   G1RegionToSpaceMapper* bot_storage =
1410     create_aux_memory_mapper("Block Offset Table",
1411                              G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1412                              G1BlockOffsetTable::heap_map_factor());
1413 
1414   G1RegionToSpaceMapper* cardtable_storage =
1415     create_aux_memory_mapper("Card Table",
1416                              G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1417                              G1CardTable::heap_map_factor());
1418 
1419   size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1420   G1RegionToSpaceMapper* bitmap_storage =
1421     create_aux_memory_mapper("Mark Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1422 
1423   _hrm.initialize(heap_storage, bitmap_storage, bot_storage, cardtable_storage);
1424   _card_table->initialize(cardtable_storage);
1425 
1426   // 6843694 - ensure that the maximum region index can fit
1427   // in the remembered set structures.
1428   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1429   guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");
1430 
1431   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1432   // start within the first card.
1433   guarantee((uintptr_t)(heap_rs.base()) >= G1CardTable::card_size(), "Java heap must not start within the first card.");
1434   G1FromCardCache::initialize(max_reserved_regions());
1435   // Also create a G1 rem set.
1436   _rem_set = new G1RemSet(this, _card_table);
1437   _rem_set->initialize(max_reserved_regions());
1438 
1439   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1440   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1441   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1442             "too many cards per region");
1443 
1444   HeapRegionRemSet::initialize(_reserved);
1445 
1446   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1447 
1448   _bot = new G1BlockOffsetTable(reserved(), bot_storage);
1449 
1450   {
1451     size_t granularity = HeapRegion::GrainBytes;
1452 
1453     _region_attr.initialize(reserved(), granularity);
1454   }
1455 
1456   _workers = new WorkerThreads("GC Thread", ParallelGCThreads);
1457   if (_workers == nullptr) {
1458     return JNI_ENOMEM;
1459   }
1460   _workers->initialize_workers();
1461 
1462   _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1463 
1464   // Create the G1ConcurrentMark data structure and thread.
1465   // (Must do this late, so that "max_[reserved_]regions" is defined.)
1466   _cm = new G1ConcurrentMark(this, bitmap_storage);
1467   _cm_thread = _cm->cm_thread();
1468 
1469   // Now expand into the initial heap size.
1470   if (!expand(init_byte_size, _workers)) {
1471     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1472     return JNI_ENOMEM;
1473   }
1474 
1475   // Perform any initialization actions delegated to the policy.
1476   policy()->init(this, &_collection_set);
1477 
1478   jint ecode = initialize_concurrent_refinement();
1479   if (ecode != JNI_OK) {
1480     return ecode;
1481   }
1482 
1483   ecode = initialize_service_thread();
1484   if (ecode != JNI_OK) {
1485     return ecode;
1486   }
1487 
1488   // Create and schedule the periodic gc task on the service thread.
1489   _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");
1490   _service_thread->register_task(_periodic_gc_task);
1491 
1492   _free_arena_memory_task = new G1MonotonicArenaFreeMemoryTask("Card Set Free Memory Task");
1493   _service_thread->register_task(_free_arena_memory_task);
1494 
1495   // Here we allocate the dummy HeapRegion that is required by the
1496   // G1AllocRegion class.
1497   HeapRegion* dummy_region = _hrm.get_dummy_region();
1498 
1499   // We'll re-use the same region whether the alloc region will
1500   // require BOT updates or not and, if it doesn't, then a non-young
1501   // region will complain that it cannot support allocations without
1502   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1503   dummy_region->set_eden();
1504   // Make sure it's full.
1505   dummy_region->set_top(dummy_region->end());
1506   G1AllocRegion::setup(this, dummy_region);
1507 
1508   _allocator->init_mutator_alloc_regions();
1509 
1510   // Do create of the monitoring and management support so that
1511   // values in the heap have been properly initialized.
1512   _monitoring_support = new G1MonitoringSupport(this);
1513 
1514   _collection_set.initialize(max_reserved_regions());
1515 
1516   evac_failure_injector()->reset();
1517 
1518   G1InitLogger::print();
1519 
1520   return JNI_OK;
1521 }
1522 
1523 bool G1CollectedHeap::concurrent_mark_is_terminating() const {
1524   return _cm_thread->should_terminate();
1525 }
1526 
1527 void G1CollectedHeap::stop() {
1528   // Stop all concurrent threads. We do this to make sure these threads
1529   // do not continue to execute and access resources (e.g. logging)
1530   // that are destroyed during shutdown.
1531   _cr->stop();
1532   _service_thread->stop();
1533   _cm_thread->stop();
1534 }
1535 
1536 void G1CollectedHeap::safepoint_synchronize_begin() {
1537   SuspendibleThreadSet::synchronize();
1538 }
1539 
1540 void G1CollectedHeap::safepoint_synchronize_end() {
1541   SuspendibleThreadSet::desynchronize();
1542 }
1543 
1544 void G1CollectedHeap::post_initialize() {
1545   CollectedHeap::post_initialize();
1546   ref_processing_init();
1547 }
1548 
1549 void G1CollectedHeap::ref_processing_init() {
1550   // Reference processing in G1 currently works as follows:
1551   //
1552   // * There are two reference processor instances. One is
1553   //   used to record and process discovered references
1554   //   during concurrent marking; the other is used to
1555   //   record and process references during STW pauses
1556   //   (both full and incremental).
1557   // * Both ref processors need to 'span' the entire heap as
1558   //   the regions in the collection set may be dotted around.
1559   //
1560   // * For the concurrent marking ref processor:
1561   //   * Reference discovery is enabled at concurrent start.
1562   //   * Reference discovery is disabled and the discovered
1563   //     references processed etc during remarking.
1564   //   * Reference discovery is MT (see below).
1565   //   * Reference discovery requires a barrier (see below).
1566   //   * Reference processing may or may not be MT
1567   //     (depending on the value of ParallelRefProcEnabled
1568   //     and ParallelGCThreads).
1569   //   * A full GC disables reference discovery by the CM
1570   //     ref processor and abandons any entries on it's
1571   //     discovered lists.
1572   //
1573   // * For the STW processor:
1574   //   * Non MT discovery is enabled at the start of a full GC.
1575   //   * Processing and enqueueing during a full GC is non-MT.
1576   //   * During a full GC, references are processed after marking.
1577   //
1578   //   * Discovery (may or may not be MT) is enabled at the start
1579   //     of an incremental evacuation pause.
1580   //   * References are processed near the end of a STW evacuation pause.
1581   //   * For both types of GC:
1582   //     * Discovery is atomic - i.e. not concurrent.
1583   //     * Reference discovery will not need a barrier.
1584 
1585   // Concurrent Mark ref processor
1586   _ref_processor_cm =
1587     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1588                            ParallelGCThreads,                              // degree of mt processing
1589                            // We discover with the gc worker threads during Remark, so both
1590                            // thread counts must be considered for discovery.
1591                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1592                            true,                                           // Reference discovery is concurrent
1593                            &_is_alive_closure_cm);                         // is alive closure
1594 
1595   // STW ref processor
1596   _ref_processor_stw =
1597     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1598                            ParallelGCThreads,                    // degree of mt processing
1599                            ParallelGCThreads,                    // degree of mt discovery
1600                            false,                                // Reference discovery is not concurrent
1601                            &_is_alive_closure_stw);              // is alive closure
1602 }
1603 
1604 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1605   return &_soft_ref_policy;
1606 }
1607 
1608 size_t G1CollectedHeap::capacity() const {
1609   return _hrm.length() * HeapRegion::GrainBytes;
1610 }
1611 
1612 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1613   return _hrm.total_free_bytes();
1614 }
1615 
1616 // Computes the sum of the storage used by the various regions.
1617 size_t G1CollectedHeap::used() const {
1618   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1619   return result;
1620 }
1621 
1622 size_t G1CollectedHeap::used_unlocked() const {
1623   return _summary_bytes_used;
1624 }
1625 
1626 class SumUsedClosure: public HeapRegionClosure {
1627   size_t _used;
1628 public:
1629   SumUsedClosure() : _used(0) {}
1630   bool do_heap_region(HeapRegion* r) {
1631     _used += r->used();
1632     return false;
1633   }
1634   size_t result() { return _used; }
1635 };
1636 
1637 size_t G1CollectedHeap::recalculate_used() const {
1638   SumUsedClosure blk;
1639   heap_region_iterate(&blk);
1640   return blk.result();
1641 }
1642 
1643 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1644   return GCCause::is_user_requested_gc(cause) && ExplicitGCInvokesConcurrent;
1645 }
1646 
1647 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1648   switch (cause) {
1649     case GCCause::_g1_humongous_allocation: return true;
1650     case GCCause::_g1_periodic_collection:  return G1PeriodicGCInvokesConcurrent;
1651     case GCCause::_wb_breakpoint:           return true;
1652     case GCCause::_codecache_GC_aggressive: return true;
1653     case GCCause::_codecache_GC_threshold:  return true;
1654     default:                                return is_user_requested_concurrent_full_gc(cause);
1655   }
1656 }
1657 
1658 void G1CollectedHeap::increment_old_marking_cycles_started() {
1659   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1660          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1661          "Wrong marking cycle count (started: %d, completed: %d)",
1662          _old_marking_cycles_started, _old_marking_cycles_completed);
1663 
1664   _old_marking_cycles_started++;
1665 }
1666 
1667 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1668                                                              bool whole_heap_examined) {
1669   MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1670 
1671   // We assume that if concurrent == true, then the caller is a
1672   // concurrent thread that was joined the Suspendible Thread
1673   // Set. If there's ever a cheap way to check this, we should add an
1674   // assert here.
1675 
1676   // Given that this method is called at the end of a Full GC or of a
1677   // concurrent cycle, and those can be nested (i.e., a Full GC can
1678   // interrupt a concurrent cycle), the number of full collections
1679   // completed should be either one (in the case where there was no
1680   // nesting) or two (when a Full GC interrupted a concurrent cycle)
1681   // behind the number of full collections started.
1682 
1683   // This is the case for the inner caller, i.e. a Full GC.
1684   assert(concurrent ||
1685          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1686          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1687          "for inner caller (Full GC): _old_marking_cycles_started = %u "
1688          "is inconsistent with _old_marking_cycles_completed = %u",
1689          _old_marking_cycles_started, _old_marking_cycles_completed);
1690 
1691   // This is the case for the outer caller, i.e. the concurrent cycle.
1692   assert(!concurrent ||
1693          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1694          "for outer caller (concurrent cycle): "
1695          "_old_marking_cycles_started = %u "
1696          "is inconsistent with _old_marking_cycles_completed = %u",
1697          _old_marking_cycles_started, _old_marking_cycles_completed);
1698 
1699   _old_marking_cycles_completed += 1;
1700   if (whole_heap_examined) {
1701     // Signal that we have completed a visit to all live objects.
1702     record_whole_heap_examined_timestamp();
1703   }
1704 
1705   // We need to clear the "in_progress" flag in the CM thread before
1706   // we wake up any waiters (especially when ExplicitInvokesConcurrent
1707   // is set) so that if a waiter requests another System.gc() it doesn't
1708   // incorrectly see that a marking cycle is still in progress.
1709   if (concurrent) {
1710     _cm_thread->set_idle();
1711   }
1712 
1713   // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
1714   // for a full GC to finish that their wait is over.
1715   ml.notify_all();
1716 }
1717 
1718 // Helper for collect().
1719 static G1GCCounters collection_counters(G1CollectedHeap* g1h) {
1720   MutexLocker ml(Heap_lock);
1721   return G1GCCounters(g1h);
1722 }
1723 
1724 void G1CollectedHeap::collect(GCCause::Cause cause) {
1725   try_collect(cause, collection_counters(this));
1726 }
1727 
1728 // Return true if (x < y) with allowance for wraparound.
1729 static bool gc_counter_less_than(uint x, uint y) {
1730   return (x - y) > (UINT_MAX/2);
1731 }
1732 
1733 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
1734 // Macro so msg printing is format-checked.
1735 #define LOG_COLLECT_CONCURRENTLY(cause, ...)                            \
1736   do {                                                                  \
1737     LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt;                   \
1738     if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) {                     \
1739       ResourceMark rm; /* For thread name. */                           \
1740       LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
1741       LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
1742                                        Thread::current()->name(),       \
1743                                        GCCause::to_string(cause));      \
1744       LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__);                    \
1745     }                                                                   \
1746   } while (0)
1747 
1748 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
1749   LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
1750 
1751 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
1752                                                uint gc_counter,
1753                                                uint old_marking_started_before) {
1754   assert_heap_not_locked();
1755   assert(should_do_concurrent_full_gc(cause),
1756          "Non-concurrent cause %s", GCCause::to_string(cause));
1757 
1758   for (uint i = 1; true; ++i) {
1759     // Try to schedule concurrent start evacuation pause that will
1760     // start a concurrent cycle.
1761     LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
1762     VM_G1TryInitiateConcMark op(gc_counter, cause);
1763     VMThread::execute(&op);
1764 
1765     // Request is trivially finished.
1766     if (cause == GCCause::_g1_periodic_collection) {
1767       LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
1768       return op.gc_succeeded();
1769     }
1770 
1771     // If VMOp skipped initiating concurrent marking cycle because
1772     // we're terminating, then we're done.
1773     if (op.terminating()) {
1774       LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
1775       return false;
1776     }
1777 
1778     // Lock to get consistent set of values.
1779     uint old_marking_started_after;
1780     uint old_marking_completed_after;
1781     {
1782       MutexLocker ml(Heap_lock);
1783       // Update gc_counter for retrying VMOp if needed. Captured here to be
1784       // consistent with the values we use below for termination tests.  If
1785       // a retry is needed after a possible wait, and another collection
1786       // occurs in the meantime, it will cause our retry to be skipped and
1787       // we'll recheck for termination with updated conditions from that
1788       // more recent collection.  That's what we want, rather than having
1789       // our retry possibly perform an unnecessary collection.
1790       gc_counter = total_collections();
1791       old_marking_started_after = _old_marking_cycles_started;
1792       old_marking_completed_after = _old_marking_cycles_completed;
1793     }
1794 
1795     if (cause == GCCause::_wb_breakpoint) {
1796       if (op.gc_succeeded()) {
1797         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1798         return true;
1799       }
1800       // When _wb_breakpoint there can't be another cycle or deferred.
1801       assert(!op.cycle_already_in_progress(), "invariant");
1802       assert(!op.whitebox_attached(), "invariant");
1803       // Concurrent cycle attempt might have been cancelled by some other
1804       // collection, so retry.  Unlike other cases below, we want to retry
1805       // even if cancelled by a STW full collection, because we really want
1806       // to start a concurrent cycle.
1807       if (old_marking_started_before != old_marking_started_after) {
1808         LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
1809         old_marking_started_before = old_marking_started_after;
1810       }
1811     } else if (!GCCause::is_user_requested_gc(cause)) {
1812       // For an "automatic" (not user-requested) collection, we just need to
1813       // ensure that progress is made.
1814       //
1815       // Request is finished if any of
1816       // (1) the VMOp successfully performed a GC,
1817       // (2) a concurrent cycle was already in progress,
1818       // (3) whitebox is controlling concurrent cycles,
1819       // (4) a new cycle was started (by this thread or some other), or
1820       // (5) a Full GC was performed.
1821       // Cases (4) and (5) are detected together by a change to
1822       // _old_marking_cycles_started.
1823       //
1824       // Note that (1) does not imply (4).  If we're still in the mixed
1825       // phase of an earlier concurrent collection, the request to make the
1826       // collection a concurrent start won't be honored.  If we don't check for
1827       // both conditions we'll spin doing back-to-back collections.
1828       if (op.gc_succeeded() ||
1829           op.cycle_already_in_progress() ||
1830           op.whitebox_attached() ||
1831           (old_marking_started_before != old_marking_started_after)) {
1832         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1833         return true;
1834       }
1835     } else {                    // User-requested GC.
1836       // For a user-requested collection, we want to ensure that a complete
1837       // full collection has been performed before returning, but without
1838       // waiting for more than needed.
1839 
1840       // For user-requested GCs (unlike non-UR), a successful VMOp implies a
1841       // new cycle was started.  That's good, because it's not clear what we
1842       // should do otherwise.  Trying again just does back to back GCs.
1843       // Can't wait for someone else to start a cycle.  And returning fails
1844       // to meet the goal of ensuring a full collection was performed.
1845       assert(!op.gc_succeeded() ||
1846              (old_marking_started_before != old_marking_started_after),
1847              "invariant: succeeded %s, started before %u, started after %u",
1848              BOOL_TO_STR(op.gc_succeeded()),
1849              old_marking_started_before, old_marking_started_after);
1850 
1851       // Request is finished if a full collection (concurrent or stw)
1852       // was started after this request and has completed, e.g.
1853       // started_before < completed_after.
1854       if (gc_counter_less_than(old_marking_started_before,
1855                                old_marking_completed_after)) {
1856         LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1857         return true;
1858       }
1859 
1860       if (old_marking_started_after != old_marking_completed_after) {
1861         // If there is an in-progress cycle (possibly started by us), then
1862         // wait for that cycle to complete, e.g.
1863         // while completed_now < started_after.
1864         LOG_COLLECT_CONCURRENTLY(cause, "wait");
1865         MonitorLocker ml(G1OldGCCount_lock);
1866         while (gc_counter_less_than(_old_marking_cycles_completed,
1867                                     old_marking_started_after)) {
1868           ml.wait();
1869         }
1870         // Request is finished if the collection we just waited for was
1871         // started after this request.
1872         if (old_marking_started_before != old_marking_started_after) {
1873           LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
1874           return true;
1875         }
1876       }
1877 
1878       // If VMOp was successful then it started a new cycle that the above
1879       // wait &etc should have recognized as finishing this request.  This
1880       // differs from a non-user-request, where gc_succeeded does not imply
1881       // a new cycle was started.
1882       assert(!op.gc_succeeded(), "invariant");
1883 
1884       if (op.cycle_already_in_progress()) {
1885         // If VMOp failed because a cycle was already in progress, it
1886         // is now complete.  But it didn't finish this user-requested
1887         // GC, so try again.
1888         LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
1889         continue;
1890       } else if (op.whitebox_attached()) {
1891         // If WhiteBox wants control, wait for notification of a state
1892         // change in the controller, then try again.  Don't wait for
1893         // release of control, since collections may complete while in
1894         // control.  Note: This won't recognize a STW full collection
1895         // while waiting; we can't wait on multiple monitors.
1896         LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
1897         MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
1898         if (ConcurrentGCBreakpoints::is_controlled()) {
1899           ml.wait();
1900         }
1901         continue;
1902       }
1903     }
1904 
1905     // Collection failed and should be retried.
1906     assert(op.transient_failure(), "invariant");
1907 
1908     if (GCLocker::is_active_and_needs_gc()) {
1909       // If GCLocker is active, wait until clear before retrying.
1910       LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
1911       GCLocker::stall_until_clear();
1912     }
1913 
1914     LOG_COLLECT_CONCURRENTLY(cause, "retry");
1915   }
1916 }
1917 
1918 bool G1CollectedHeap::try_collect_fullgc(GCCause::Cause cause,
1919                                          const G1GCCounters& counters_before) {
1920   assert_heap_not_locked();
1921 
1922   while(true) {
1923     VM_G1CollectFull op(counters_before.total_collections(),
1924                         counters_before.total_full_collections(),
1925                         cause);
1926     VMThread::execute(&op);
1927 
1928     // Request is trivially finished.
1929     if (!GCCause::is_explicit_full_gc(cause) || op.gc_succeeded()) {
1930       return op.gc_succeeded();
1931     }
1932 
1933     {
1934       MutexLocker ml(Heap_lock);
1935       if (counters_before.total_full_collections() != total_full_collections()) {
1936         return true;
1937       }
1938     }
1939 
1940     if (GCLocker::is_active_and_needs_gc()) {
1941       // If GCLocker is active, wait until clear before retrying.
1942       GCLocker::stall_until_clear();
1943     }
1944   }
1945 }
1946 
1947 bool G1CollectedHeap::try_collect(GCCause::Cause cause,
1948                                   const G1GCCounters& counters_before) {
1949   if (should_do_concurrent_full_gc(cause)) {
1950     return try_collect_concurrently(cause,
1951                                     counters_before.total_collections(),
1952                                     counters_before.old_marking_cycles_started());
1953   } else if (GCLocker::should_discard(cause, counters_before.total_collections())) {
1954     // Indicate failure to be consistent with VMOp failure due to
1955     // another collection slipping in after our gc_count but before
1956     // our request is processed.
1957     return false;
1958   } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
1959              DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
1960 
1961     // Schedule a standard evacuation pause. We're setting word_size
1962     // to 0 which means that we are not requesting a post-GC allocation.
1963     VM_G1CollectForAllocation op(0,     /* word_size */
1964                                  counters_before.total_collections(),
1965                                  cause);
1966     VMThread::execute(&op);
1967     return op.gc_succeeded();
1968   } else {
1969     // Schedule a Full GC.
1970     return try_collect_fullgc(cause, counters_before);
1971   }
1972 }
1973 
1974 void G1CollectedHeap::start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause) {
1975   GCCauseSetter x(this, gc_cause);
1976 
1977   // At this point we are supposed to start a concurrent cycle. We
1978   // will do so if one is not already in progress.
1979   bool should_start = policy()->force_concurrent_start_if_outside_cycle(gc_cause);
1980   if (should_start) {
1981     do_collection_pause_at_safepoint();
1982   }
1983 }
1984 
1985 bool G1CollectedHeap::is_in(const void* p) const {
1986   return is_in_reserved(p) && _hrm.is_available(addr_to_region(p));
1987 }
1988 
1989 // Iteration functions.
1990 
1991 // Iterates an ObjectClosure over all objects within a HeapRegion.
1992 
1993 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1994   ObjectClosure* _cl;
1995 public:
1996   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1997   bool do_heap_region(HeapRegion* r) {
1998     if (!r->is_continues_humongous()) {
1999       r->object_iterate(_cl);
2000     }
2001     return false;
2002   }
2003 };
2004 
2005 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2006   IterateObjectClosureRegionClosure blk(cl);
2007   heap_region_iterate(&blk);
2008 }
2009 
2010 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl {
2011 private:
2012   G1CollectedHeap*  _heap;
2013   HeapRegionClaimer _claimer;
2014 
2015 public:
2016   G1ParallelObjectIterator(uint thread_num) :
2017       _heap(G1CollectedHeap::heap()),
2018       _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2019 
2020   virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2021     _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2022   }
2023 };
2024 
2025 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2026   return new G1ParallelObjectIterator(thread_num);
2027 }
2028 
2029 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2030   IterateObjectClosureRegionClosure blk(cl);
2031   heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2032 }
2033 
2034 void G1CollectedHeap::keep_alive(oop obj) {
2035   G1BarrierSet::enqueue_preloaded(obj);
2036 }
2037 
2038 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2039   _hrm.iterate(cl);
2040 }
2041 
2042 void G1CollectedHeap::heap_region_iterate(HeapRegionIndexClosure* cl) const {
2043   _hrm.iterate(cl);
2044 }
2045 
2046 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2047                                                                  HeapRegionClaimer *hrclaimer,
2048                                                                  uint worker_id) const {
2049   _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2050 }
2051 
2052 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2053                                                          HeapRegionClaimer *hrclaimer) const {
2054   _hrm.par_iterate(cl, hrclaimer, 0);
2055 }
2056 
2057 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2058   _collection_set.iterate(cl);
2059 }
2060 
2061 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl,
2062                                                      HeapRegionClaimer* hr_claimer,
2063                                                      uint worker_id) {
2064   _collection_set.par_iterate(cl, hr_claimer, worker_id);
2065 }
2066 
2067 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl,
2068                                                             HeapRegionClaimer* hr_claimer,
2069                                                             uint worker_id) {
2070   _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id);
2071 }
2072 
2073 void G1CollectedHeap::par_iterate_regions_array(HeapRegionClosure* cl,
2074                                                 HeapRegionClaimer* hr_claimer,
2075                                                 const uint regions[],
2076                                                 size_t length,
2077                                                 uint worker_id) const {
2078   assert_at_safepoint();
2079   if (length == 0) {
2080     return;
2081   }
2082   uint total_workers = workers()->active_workers();
2083 
2084   size_t start_pos = (worker_id * length) / total_workers;
2085   size_t cur_pos = start_pos;
2086 
2087   do {
2088     uint region_idx = regions[cur_pos];
2089     if (hr_claimer == nullptr || hr_claimer->claim_region(region_idx)) {
2090       HeapRegion* r = region_at(region_idx);
2091       bool result = cl->do_heap_region(r);
2092       guarantee(!result, "Must not cancel iteration");
2093     }
2094 
2095     cur_pos++;
2096     if (cur_pos == length) {
2097       cur_pos = 0;
2098     }
2099   } while (cur_pos != start_pos);
2100 }
2101 
2102 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2103   HeapRegion* hr = heap_region_containing(addr);
2104   // The CollectedHeap API requires us to not fail for any given address within
2105   // the heap. HeapRegion::block_start() has been optimized to not accept addresses
2106   // outside of the allocated area.
2107   if (addr >= hr->top()) {
2108     return nullptr;
2109   }
2110   return hr->block_start(addr);
2111 }
2112 
2113 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2114   HeapRegion* hr = heap_region_containing(addr);
2115   return hr->block_is_obj(addr, hr->parsable_bottom_acquire());
2116 }
2117 
2118 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2119   return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2120 }
2121 
2122 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2123   return _eden.length() * HeapRegion::GrainBytes;
2124 }
2125 
2126 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2127 // must be equal to the humongous object limit.
2128 size_t G1CollectedHeap::max_tlab_size() const {
2129   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2130 }
2131 
2132 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2133   return _allocator->unsafe_max_tlab_alloc();
2134 }
2135 
2136 size_t G1CollectedHeap::max_capacity() const {
2137   return max_regions() * HeapRegion::GrainBytes;
2138 }
2139 
2140 void G1CollectedHeap::prepare_for_verify() {
2141   _verifier->prepare_for_verify();
2142 }
2143 
2144 void G1CollectedHeap::verify(VerifyOption vo) {
2145   _verifier->verify(vo);
2146 }
2147 
2148 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2149   return true;
2150 }
2151 
2152 class PrintRegionClosure: public HeapRegionClosure {
2153   outputStream* _st;
2154 public:
2155   PrintRegionClosure(outputStream* st) : _st(st) {}
2156   bool do_heap_region(HeapRegion* r) {
2157     r->print_on(_st);
2158     return false;
2159   }
2160 };
2161 
2162 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2163                                        const HeapRegion* hr,
2164                                        const VerifyOption vo) const {
2165   switch (vo) {
2166     case VerifyOption::G1UseConcMarking: return is_obj_dead(obj, hr);
2167     case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj, hr);
2168     default:                             ShouldNotReachHere();
2169   }
2170   return false; // keep some compilers happy
2171 }
2172 
2173 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2174                                        const VerifyOption vo) const {
2175   switch (vo) {
2176     case VerifyOption::G1UseConcMarking: return is_obj_dead(obj);
2177     case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj);
2178     default:                             ShouldNotReachHere();
2179   }
2180   return false; // keep some compilers happy
2181 }
2182 
2183 void G1CollectedHeap::pin_object(JavaThread* thread, oop obj) {
2184   GCLocker::lock_critical(thread);
2185 }
2186 
2187 void G1CollectedHeap::unpin_object(JavaThread* thread, oop obj) {
2188   GCLocker::unlock_critical(thread);
2189 }
2190 
2191 void G1CollectedHeap::print_heap_regions() const {
2192   LogTarget(Trace, gc, heap, region) lt;
2193   if (lt.is_enabled()) {
2194     LogStream ls(lt);
2195     print_regions_on(&ls);
2196   }
2197 }
2198 
2199 void G1CollectedHeap::print_on(outputStream* st) const {
2200   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2201   st->print(" %-20s", "garbage-first heap");
2202   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2203             capacity()/K, heap_used/K);
2204   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2205             p2i(_hrm.reserved().start()),
2206             p2i(_hrm.reserved().end()));
2207   st->cr();
2208   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2209   uint young_regions = young_regions_count();
2210   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2211             (size_t) young_regions * HeapRegion::GrainBytes / K);
2212   uint survivor_regions = survivor_regions_count();
2213   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2214             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2215   st->cr();
2216   if (_numa->is_enabled()) {
2217     uint num_nodes = _numa->num_active_nodes();
2218     st->print("  remaining free region(s) on each NUMA node: ");
2219     const int* node_ids = _numa->node_ids();
2220     for (uint node_index = 0; node_index < num_nodes; node_index++) {
2221       uint num_free_regions = _hrm.num_free_regions(node_index);
2222       st->print("%d=%u ", node_ids[node_index], num_free_regions);
2223     }
2224     st->cr();
2225   }
2226   MetaspaceUtils::print_on(st);
2227 }
2228 
2229 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2230   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2231                "HS=humongous(starts), HC=humongous(continues), "
2232                "CS=collection set, F=free, "
2233                "TAMS=top-at-mark-start, "
2234                "PB=parsable bottom");
2235   PrintRegionClosure blk(st);
2236   heap_region_iterate(&blk);
2237 }
2238 
2239 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2240   print_on(st);
2241 
2242   // Print the per-region information.
2243   st->cr();
2244   print_regions_on(st);
2245 }
2246 
2247 void G1CollectedHeap::print_on_error(outputStream* st) const {
2248   this->CollectedHeap::print_on_error(st);
2249 
2250   if (_cm != nullptr) {
2251     st->cr();
2252     _cm->print_on_error(st);
2253   }
2254 }
2255 
2256 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2257   workers()->threads_do(tc);
2258   tc->do_thread(_cm_thread);
2259   _cm->threads_do(tc);
2260   _cr->threads_do(tc);
2261   tc->do_thread(_service_thread);
2262 }
2263 
2264 void G1CollectedHeap::print_tracing_info() const {
2265   rem_set()->print_summary_info();
2266   concurrent_mark()->print_summary_info();
2267 }
2268 
2269 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2270   return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2271 }
2272 
2273 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2274 
2275   size_t eden_used_bytes = _monitoring_support->eden_space_used();
2276   size_t survivor_used_bytes = _monitoring_support->survivor_space_used();
2277   size_t old_gen_used_bytes = _monitoring_support->old_gen_used();
2278   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2279 
2280   size_t eden_capacity_bytes =
2281     (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2282 
2283   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2284   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, eden_capacity_bytes,
2285                        survivor_used_bytes, old_gen_used_bytes, num_regions());
2286 }
2287 
2288 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2289   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2290                        stats->unused(), stats->used(), stats->region_end_waste(),
2291                        stats->regions_filled(), stats->num_plab_filled(),
2292                        stats->direct_allocated(), stats->num_direct_allocated(),
2293                        stats->failure_used(), stats->failure_waste());
2294 }
2295 
2296 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2297   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2298   gc_tracer->report_gc_heap_summary(when, heap_summary);
2299 
2300   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2301   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2302 }
2303 
2304 void G1CollectedHeap::gc_prologue(bool full) {
2305   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2306 
2307   // Update common counters.
2308   increment_total_collections(full /* full gc */);
2309   if (full || collector_state()->in_concurrent_start_gc()) {
2310     increment_old_marking_cycles_started();
2311   }
2312 }
2313 
2314 void G1CollectedHeap::gc_epilogue(bool full) {
2315   // Update common counters.
2316   if (full) {
2317     // Update the number of full collections that have been completed.
2318     increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2319   }
2320 
2321 #if COMPILER2_OR_JVMCI
2322   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2323 #endif
2324 
2325   // We have just completed a GC. Update the soft reference
2326   // policy with the new heap occupancy
2327   Universe::heap()->update_capacity_and_used_at_gc();
2328 
2329   _collection_pause_end = Ticks::now();
2330 
2331   _free_arena_memory_task->notify_new_stats(&_young_gen_card_set_stats,
2332                                             &_collection_set_candidates_card_set_stats);
2333 }
2334 
2335 uint G1CollectedHeap::uncommit_regions(uint region_limit) {
2336   return _hrm.uncommit_inactive_regions(region_limit);
2337 }
2338 
2339 bool G1CollectedHeap::has_uncommittable_regions() {
2340   return _hrm.has_inactive_regions();
2341 }
2342 
2343 void G1CollectedHeap::uncommit_regions_if_necessary() {
2344   if (has_uncommittable_regions()) {
2345     G1UncommitRegionTask::enqueue();
2346   }
2347 }
2348 
2349 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2350   LogTarget(Trace, gc, heap, verify) lt;
2351 
2352   if (lt.is_enabled()) {
2353     LogStream ls(lt);
2354     // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2355     G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2356     heap_region_iterate(&cl);
2357   }
2358 }
2359 
2360 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2361                                                uint gc_count_before,
2362                                                bool* succeeded,
2363                                                GCCause::Cause gc_cause) {
2364   assert_heap_not_locked_and_not_at_safepoint();
2365   VM_G1CollectForAllocation op(word_size, gc_count_before, gc_cause);
2366   VMThread::execute(&op);
2367 
2368   HeapWord* result = op.result();
2369   bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2370   assert(result == nullptr || ret_succeeded,
2371          "the result should be null if the VM did not succeed");
2372   *succeeded = ret_succeeded;
2373 
2374   assert_heap_not_locked();
2375   return result;
2376 }
2377 
2378 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) {
2379   assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress");
2380 
2381   MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2382   if (concurrent_operation_is_full_mark) {
2383     _cm->post_concurrent_mark_start();
2384     _cm_thread->start_full_mark();
2385   } else {
2386     _cm->post_concurrent_undo_start();
2387     _cm_thread->start_undo_mark();
2388   }
2389   CGC_lock->notify();
2390 }
2391 
2392 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2393   // We don't nominate objects with many remembered set entries, on
2394   // the assumption that such objects are likely still live.
2395   HeapRegionRemSet* rem_set = r->rem_set();
2396 
2397   return rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold);
2398 }
2399 
2400 #ifndef PRODUCT
2401 void G1CollectedHeap::verify_region_attr_remset_is_tracked() {
2402   class VerifyRegionAttrRemSet : public HeapRegionClosure {
2403   public:
2404     virtual bool do_heap_region(HeapRegion* r) {
2405       G1CollectedHeap* g1h = G1CollectedHeap::heap();
2406       bool const remset_is_tracked = g1h->region_attr(r->bottom()).remset_is_tracked();
2407       assert(r->rem_set()->is_tracked() == remset_is_tracked,
2408              "Region %u remset tracking status (%s) different to region attribute (%s)",
2409              r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(remset_is_tracked));
2410       return false;
2411     }
2412   } cl;
2413   heap_region_iterate(&cl);
2414 }
2415 #endif
2416 
2417 void G1CollectedHeap::start_new_collection_set() {
2418   collection_set()->start_incremental_building();
2419 
2420   clear_region_attr();
2421 
2422   guarantee(_eden.length() == 0, "eden should have been cleared");
2423   policy()->transfer_survivors_to_cset(survivor());
2424 
2425   // We redo the verification but now wrt to the new CSet which
2426   // has just got initialized after the previous CSet was freed.
2427   _cm->verify_no_collection_set_oops();
2428 }
2429 
2430 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2431   if (collector_state()->in_concurrent_start_gc()) {
2432     return G1HeapVerifier::G1VerifyConcurrentStart;
2433   } else if (collector_state()->in_young_only_phase()) {
2434     return G1HeapVerifier::G1VerifyYoungNormal;
2435   } else {
2436     return G1HeapVerifier::G1VerifyMixed;
2437   }
2438 }
2439 
2440 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2441   if (!VerifyBeforeGC) {
2442     return;
2443   }
2444   if (!G1HeapVerifier::should_verify(type)) {
2445     return;
2446   }
2447   Ticks start = Ticks::now();
2448   _verifier->prepare_for_verify();
2449   _verifier->verify_region_sets_optional();
2450   _verifier->verify_dirty_young_regions();
2451   _verifier->verify_before_gc();
2452   verify_numa_regions("GC Start");
2453   phase_times()->record_verify_before_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2454 }
2455 
2456 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2457   if (!VerifyAfterGC) {
2458     return;
2459   }
2460   if (!G1HeapVerifier::should_verify(type)) {
2461     return;
2462   }
2463   Ticks start = Ticks::now();
2464   _verifier->verify_after_gc();
2465   verify_numa_regions("GC End");
2466   _verifier->verify_region_sets_optional();
2467 
2468   if (collector_state()->in_concurrent_start_gc()) {
2469     log_debug(gc, verify)("Marking state");
2470     _verifier->verify_marking_state();
2471   }
2472 
2473   phase_times()->record_verify_after_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2474 }
2475 
2476 void G1CollectedHeap::expand_heap_after_young_collection(){
2477   size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2478   if (expand_bytes > 0) {
2479     // No need for an ergo logging here,
2480     // expansion_amount() does this when it returns a value > 0.
2481     double expand_ms = 0.0;
2482     if (!expand(expand_bytes, _workers, &expand_ms)) {
2483       // We failed to expand the heap. Cannot do anything about it.
2484     }
2485     phase_times()->record_expand_heap_time(expand_ms);
2486   }
2487 }
2488 
2489 bool G1CollectedHeap::do_collection_pause_at_safepoint() {
2490   assert_at_safepoint_on_vm_thread();
2491   guarantee(!is_gc_active(), "collection is not reentrant");
2492 
2493   if (GCLocker::check_active_before_gc()) {
2494     return false;
2495   }
2496 
2497   do_collection_pause_at_safepoint_helper();
2498   return true;
2499 }
2500 
2501 G1HeapPrinterMark::G1HeapPrinterMark(G1CollectedHeap* g1h) : _g1h(g1h), _heap_transition(g1h) {
2502   // This summary needs to be printed before incrementing total collections.
2503   _g1h->rem_set()->print_periodic_summary_info("Before GC RS summary",
2504                                                _g1h->total_collections(),
2505                                                true /* show_thread_times */);
2506   _g1h->print_heap_before_gc();
2507   _g1h->print_heap_regions();
2508 }
2509 
2510 G1HeapPrinterMark::~G1HeapPrinterMark() {
2511   _g1h->policy()->print_age_table();
2512   _g1h->rem_set()->print_coarsen_stats();
2513   // We are at the end of the GC. Total collections has already been increased.
2514   _g1h->rem_set()->print_periodic_summary_info("After GC RS summary",
2515                                                _g1h->total_collections() - 1,
2516                                                false /* show_thread_times */);
2517 
2518   _heap_transition.print();
2519   _g1h->print_heap_regions();
2520   _g1h->print_heap_after_gc();
2521   // Print NUMA statistics.
2522   _g1h->numa()->print_statistics();
2523 }
2524 
2525 G1JFRTracerMark::G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer) :
2526   _timer(timer), _tracer(tracer) {
2527 
2528   _timer->register_gc_start();
2529   _tracer->report_gc_start(G1CollectedHeap::heap()->gc_cause(), _timer->gc_start());
2530   G1CollectedHeap::heap()->trace_heap_before_gc(_tracer);
2531 }
2532 
2533 G1JFRTracerMark::~G1JFRTracerMark() {
2534   G1CollectedHeap::heap()->trace_heap_after_gc(_tracer);
2535   _timer->register_gc_end();
2536   _tracer->report_gc_end(_timer->gc_end(), _timer->time_partitions());
2537 }
2538 
2539 void G1CollectedHeap::prepare_for_mutator_after_young_collection() {
2540   Ticks start = Ticks::now();
2541 
2542   _survivor_evac_stats.adjust_desired_plab_size();
2543   _old_evac_stats.adjust_desired_plab_size();
2544 
2545   // Start a new incremental collection set for the mutator phase.
2546   start_new_collection_set();
2547   _allocator->init_mutator_alloc_regions();
2548 
2549   phase_times()->record_prepare_for_mutator_time_ms((Ticks::now() - start).seconds() * 1000.0);
2550 }
2551 
2552 void G1CollectedHeap::retire_tlabs() {
2553   ensure_parsability(true);
2554 }
2555 
2556 void G1CollectedHeap::do_collection_pause_at_safepoint_helper() {
2557   ResourceMark rm;
2558 
2559   IsGCActiveMark active_gc_mark;
2560   GCIdMark gc_id_mark;
2561   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2562 
2563   GCTraceCPUTime tcpu(_gc_tracer_stw);
2564 
2565   _bytes_used_during_gc = 0;
2566 
2567   policy()->decide_on_concurrent_start_pause();
2568   // Record whether this pause may need to trigger a concurrent operation. Later,
2569   // when we signal the G1ConcurrentMarkThread, the collector state has already
2570   // been reset for the next pause.
2571   bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc();
2572 
2573   // Perform the collection.
2574   G1YoungCollector collector(gc_cause());
2575   collector.collect();
2576 
2577   // It should now be safe to tell the concurrent mark thread to start
2578   // without its logging output interfering with the logging output
2579   // that came from the pause.
2580   if (should_start_concurrent_mark_operation) {
2581     verifier()->verify_bitmap_clear(true /* above_tams_only */);
2582     // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking
2583     // thread(s) could be running concurrently with us. Make sure that anything
2584     // after this point does not assume that we are the only GC thread running.
2585     // Note: of course, the actual marking work will not start until the safepoint
2586     // itself is released in SuspendibleThreadSet::desynchronize().
2587     start_concurrent_cycle(collector.concurrent_operation_is_full_mark());
2588     ConcurrentGCBreakpoints::notify_idle_to_active();
2589   }
2590 }
2591 
2592 void G1CollectedHeap::complete_cleaning(bool class_unloading_occurred) {
2593   uint num_workers = workers()->active_workers();
2594   G1ParallelCleaningTask unlink_task(num_workers, class_unloading_occurred);
2595   workers()->run_task(&unlink_task);
2596 }
2597 
2598 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
2599   assert(obj != nullptr, "must not be null");
2600   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
2601   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
2602   // may falsely indicate that this is not the case here: however the collection set only
2603   // contains old regions when concurrent mark is not running.
2604   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
2605 }
2606 
2607 void G1CollectedHeap::make_pending_list_reachable() {
2608   if (collector_state()->in_concurrent_start_gc()) {
2609     oop pll_head = Universe::reference_pending_list();
2610     if (pll_head != nullptr) {
2611       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
2612       _cm->mark_in_bitmap(0 /* worker_id */, pll_head);
2613     }
2614   }
2615 }
2616 
2617 void G1CollectedHeap::set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates) {
2618   _num_humongous_objects = num_humongous_total;
2619   _num_humongous_reclaim_candidates = num_humongous_candidates;
2620 }
2621 
2622 bool G1CollectedHeap::should_sample_collection_set_candidates() const {
2623   const G1CollectionSetCandidates* candidates = collection_set()->candidates();
2624   return !candidates->is_empty();
2625 }
2626 
2627 void G1CollectedHeap::set_collection_set_candidates_stats(G1MonotonicArenaMemoryStats& stats) {
2628   _collection_set_candidates_card_set_stats = stats;
2629 }
2630 
2631 void G1CollectedHeap::set_young_gen_card_set_stats(const G1MonotonicArenaMemoryStats& stats) {
2632   _young_gen_card_set_stats = stats;
2633 }
2634 
2635 void G1CollectedHeap::record_obj_copy_mem_stats() {
2636   policy()->old_gen_alloc_tracker()->
2637     add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
2638 
2639   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
2640                                                create_g1_evac_summary(&_old_evac_stats));
2641 }
2642 
2643 void G1CollectedHeap::clear_bitmap_for_region(HeapRegion* hr) {
2644   concurrent_mark()->clear_bitmap_for_region(hr);
2645 }
2646 
2647 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
2648   assert(!hr->is_free(), "the region should not be free");
2649   assert(!hr->is_empty(), "the region should not be empty");
2650   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
2651 
2652   // Reset region metadata to allow reuse.
2653   hr->hr_clear(true /* clear_space */);
2654   _policy->remset_tracker()->update_at_free(hr);
2655 
2656   if (free_list != nullptr) {
2657     free_list->add_ordered(hr);
2658   }
2659 }
2660 
2661 void G1CollectedHeap::retain_region(HeapRegion* hr) {
2662   MutexLocker x(G1RareEvent_lock, Mutex::_no_safepoint_check_flag);
2663   collection_set()->candidates()->add_retained_region_unsorted(hr);
2664 }
2665 
2666 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
2667                                             FreeRegionList* free_list) {
2668   assert(hr->is_humongous(), "this is only for humongous regions");
2669   hr->clear_humongous();
2670   free_region(hr, free_list);
2671 }
2672 
2673 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed,
2674                                                const uint humongous_regions_removed) {
2675   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
2676     MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
2677     _old_set.bulk_remove(old_regions_removed);
2678     _humongous_set.bulk_remove(humongous_regions_removed);
2679   }
2680 
2681 }
2682 
2683 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
2684   assert(list != nullptr, "list can't be null");
2685   if (!list->is_empty()) {
2686     MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
2687     _hrm.insert_list_into_free_list(list);
2688   }
2689 }
2690 
2691 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
2692   decrease_used(bytes);
2693 }
2694 
2695 void G1CollectedHeap::clear_eden() {
2696   _eden.clear();
2697 }
2698 
2699 void G1CollectedHeap::clear_collection_set() {
2700   collection_set()->clear();
2701 }
2702 
2703 void G1CollectedHeap::rebuild_free_region_list() {
2704   Ticks start = Ticks::now();
2705   _hrm.rebuild_free_list(workers());
2706   phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
2707 }
2708 
2709 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
2710 public:
2711   virtual bool do_heap_region(HeapRegion* r) {
2712     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
2713     G1CollectedHeap::heap()->clear_region_attr(r);
2714     r->clear_young_index_in_cset();
2715     return false;
2716   }
2717 };
2718 
2719 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
2720   G1AbandonCollectionSetClosure cl;
2721   collection_set_iterate_all(&cl);
2722 
2723   collection_set->clear();
2724   collection_set->stop_incremental_building();
2725 }
2726 
2727 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
2728   return _allocator->is_retained_old_region(hr);
2729 }
2730 
2731 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
2732   _eden.add(hr);
2733   _policy->set_region_eden(hr);
2734 }
2735 
2736 #ifdef ASSERT
2737 
2738 class NoYoungRegionsClosure: public HeapRegionClosure {
2739 private:
2740   bool _success;
2741 public:
2742   NoYoungRegionsClosure() : _success(true) { }
2743   bool do_heap_region(HeapRegion* r) {
2744     if (r->is_young()) {
2745       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
2746                             p2i(r->bottom()), p2i(r->end()));
2747       _success = false;
2748     }
2749     return false;
2750   }
2751   bool success() { return _success; }
2752 };
2753 
2754 bool G1CollectedHeap::check_young_list_empty() {
2755   bool ret = (young_regions_count() == 0);
2756 
2757   NoYoungRegionsClosure closure;
2758   heap_region_iterate(&closure);
2759   ret = ret && closure.success();
2760 
2761   return ret;
2762 }
2763 
2764 #endif // ASSERT
2765 
2766 // Remove the given HeapRegion from the appropriate region set.
2767 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) {
2768    if (hr->is_humongous()) {
2769     _humongous_set.remove(hr);
2770   } else if (hr->is_old()) {
2771     _old_set.remove(hr);
2772   } else if (hr->is_young()) {
2773     // Note that emptying the eden and survivor lists is postponed and instead
2774     // done as the first step when rebuilding the regions sets again. The reason
2775     // for this is that during a full GC string deduplication needs to know if
2776     // a collected region was young or old when the full GC was initiated.
2777     hr->uninstall_surv_rate_group();
2778   } else {
2779     // We ignore free regions, we'll empty the free list afterwards.
2780     assert(hr->is_free(), "it cannot be another type");
2781   }
2782 }
2783 
2784 void G1CollectedHeap::increase_used(size_t bytes) {
2785   _summary_bytes_used += bytes;
2786 }
2787 
2788 void G1CollectedHeap::decrease_used(size_t bytes) {
2789   assert(_summary_bytes_used >= bytes,
2790          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
2791          _summary_bytes_used, bytes);
2792   _summary_bytes_used -= bytes;
2793 }
2794 
2795 void G1CollectedHeap::set_used(size_t bytes) {
2796   _summary_bytes_used = bytes;
2797 }
2798 
2799 class RebuildRegionSetsClosure : public HeapRegionClosure {
2800 private:
2801   bool _free_list_only;
2802 
2803   HeapRegionSet* _old_set;
2804   HeapRegionSet* _humongous_set;
2805 
2806   HeapRegionManager* _hrm;
2807 
2808   size_t _total_used;
2809 
2810 public:
2811   RebuildRegionSetsClosure(bool free_list_only,
2812                            HeapRegionSet* old_set,
2813                            HeapRegionSet* humongous_set,
2814                            HeapRegionManager* hrm) :
2815     _free_list_only(free_list_only), _old_set(old_set),
2816     _humongous_set(humongous_set), _hrm(hrm), _total_used(0) {
2817     assert(_hrm->num_free_regions() == 0, "pre-condition");
2818     if (!free_list_only) {
2819       assert(_old_set->is_empty(), "pre-condition");
2820       assert(_humongous_set->is_empty(), "pre-condition");
2821     }
2822   }
2823 
2824   bool do_heap_region(HeapRegion* r) {
2825     if (r->is_empty()) {
2826       assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
2827       // Add free regions to the free list
2828       r->set_free();
2829       _hrm->insert_into_free_list(r);
2830     } else if (!_free_list_only) {
2831       assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
2832 
2833       if (r->is_humongous()) {
2834         _humongous_set->add(r);
2835       } else {
2836         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
2837         // We now move all (non-humongous, non-old) regions to old gen,
2838         // and register them as such.
2839         r->move_to_old();
2840         _old_set->add(r);
2841       }
2842       _total_used += r->used();
2843     }
2844 
2845     return false;
2846   }
2847 
2848   size_t total_used() {
2849     return _total_used;
2850   }
2851 };
2852 
2853 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
2854   assert_at_safepoint_on_vm_thread();
2855 
2856   if (!free_list_only) {
2857     _eden.clear();
2858     _survivor.clear();
2859   }
2860 
2861   RebuildRegionSetsClosure cl(free_list_only,
2862                               &_old_set, &_humongous_set,
2863                               &_hrm);
2864   heap_region_iterate(&cl);
2865 
2866   if (!free_list_only) {
2867     set_used(cl.total_used());
2868   }
2869   assert_used_and_recalculate_used_equal(this);
2870 }
2871 
2872 // Methods for the mutator alloc region
2873 
2874 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
2875                                                       bool force,
2876                                                       uint node_index) {
2877   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
2878   bool should_allocate = policy()->should_allocate_mutator_region();
2879   if (force || should_allocate) {
2880     HeapRegion* new_alloc_region = new_region(word_size,
2881                                               HeapRegionType::Eden,
2882                                               false /* do_expand */,
2883                                               node_index);
2884     if (new_alloc_region != nullptr) {
2885       set_region_short_lived_locked(new_alloc_region);
2886       _hr_printer.alloc(new_alloc_region, !should_allocate);
2887       _policy->remset_tracker()->update_at_allocate(new_alloc_region);
2888       return new_alloc_region;
2889     }
2890   }
2891   return nullptr;
2892 }
2893 
2894 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
2895                                                   size_t allocated_bytes) {
2896   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
2897   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
2898 
2899   collection_set()->add_eden_region(alloc_region);
2900   increase_used(allocated_bytes);
2901   _eden.add_used_bytes(allocated_bytes);
2902   _hr_printer.retire(alloc_region);
2903 
2904   // We update the eden sizes here, when the region is retired,
2905   // instead of when it's allocated, since this is the point that its
2906   // used space has been recorded in _summary_bytes_used.
2907   monitoring_support()->update_eden_size();
2908 }
2909 
2910 // Methods for the GC alloc regions
2911 
2912 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
2913   if (dest.is_old()) {
2914     return true;
2915   } else {
2916     return survivor_regions_count() < policy()->max_survivor_regions();
2917   }
2918 }
2919 
2920 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
2921   assert(FreeList_lock->owned_by_self(), "pre-condition");
2922 
2923   if (!has_more_regions(dest)) {
2924     return nullptr;
2925   }
2926 
2927   HeapRegionType type;
2928   if (dest.is_young()) {
2929     type = HeapRegionType::Survivor;
2930   } else {
2931     type = HeapRegionType::Old;
2932   }
2933 
2934   HeapRegion* new_alloc_region = new_region(word_size,
2935                                             type,
2936                                             true /* do_expand */,
2937                                             node_index);
2938 
2939   if (new_alloc_region != nullptr) {
2940     if (type.is_survivor()) {
2941       new_alloc_region->set_survivor();
2942       _survivor.add(new_alloc_region);
2943       register_new_survivor_region_with_region_attr(new_alloc_region);
2944     } else {
2945       new_alloc_region->set_old();
2946     }
2947     _policy->remset_tracker()->update_at_allocate(new_alloc_region);
2948     register_region_with_region_attr(new_alloc_region);
2949     _hr_printer.alloc(new_alloc_region);
2950     return new_alloc_region;
2951   }
2952   return nullptr;
2953 }
2954 
2955 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
2956                                              size_t allocated_bytes,
2957                                              G1HeapRegionAttr dest) {
2958   _bytes_used_during_gc += allocated_bytes;
2959   if (dest.is_old()) {
2960     old_set_add(alloc_region);
2961   } else {
2962     assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
2963     _survivor.add_used_bytes(allocated_bytes);
2964   }
2965 
2966   bool const during_im = collector_state()->in_concurrent_start_gc();
2967   if (during_im && allocated_bytes > 0) {
2968     _cm->add_root_region(alloc_region);
2969   }
2970   _hr_printer.retire(alloc_region);
2971 }
2972 
2973 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
2974   bool expanded = false;
2975   uint index = _hrm.find_highest_free(&expanded);
2976 
2977   if (index != G1_NO_HRM_INDEX) {
2978     if (expanded) {
2979       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
2980                                 HeapRegion::GrainWords * HeapWordSize);
2981     }
2982     return _hrm.allocate_free_regions_starting_at(index, 1);
2983   }
2984   return nullptr;
2985 }
2986 
2987 void G1CollectedHeap::mark_evac_failure_object(uint worker_id, const oop obj, size_t obj_size) const {
2988   assert(!_cm->is_marked_in_bitmap(obj), "must be");
2989 
2990   _cm->raw_mark_in_bitmap(obj);
2991 }
2992 
2993 // Optimized nmethod scanning
2994 class RegisterNMethodOopClosure: public OopClosure {
2995   G1CollectedHeap* _g1h;
2996   nmethod* _nm;
2997 
2998 public:
2999   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3000     _g1h(g1h), _nm(nm) {}
3001 
3002   void do_oop(oop* p) {
3003     oop heap_oop = RawAccess<>::oop_load(p);
3004     if (!CompressedOops::is_null(heap_oop)) {
3005       oop obj = CompressedOops::decode_not_null(heap_oop);
3006       HeapRegion* hr = _g1h->heap_region_containing(obj);
3007       assert(!hr->is_continues_humongous(),
3008              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3009              " starting at " HR_FORMAT,
3010              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3011 
3012       // HeapRegion::add_code_root_locked() avoids adding duplicate entries.
3013       hr->add_code_root_locked(_nm);
3014     }
3015   }
3016 
3017   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3018 };
3019 
3020 class UnregisterNMethodOopClosure: public OopClosure {
3021   G1CollectedHeap* _g1h;
3022   nmethod* _nm;
3023 
3024 public:
3025   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3026     _g1h(g1h), _nm(nm) {}
3027 
3028   void do_oop(oop* p) {
3029     oop heap_oop = RawAccess<>::oop_load(p);
3030     if (!CompressedOops::is_null(heap_oop)) {
3031       oop obj = CompressedOops::decode_not_null(heap_oop);
3032       HeapRegion* hr = _g1h->heap_region_containing(obj);
3033       assert(!hr->is_continues_humongous(),
3034              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3035              " starting at " HR_FORMAT,
3036              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3037 
3038       hr->remove_code_root(_nm);
3039     }
3040   }
3041 
3042   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3043 };
3044 
3045 void G1CollectedHeap::register_nmethod(nmethod* nm) {
3046   guarantee(nm != nullptr, "sanity");
3047   RegisterNMethodOopClosure reg_cl(this, nm);
3048   nm->oops_do(&reg_cl);
3049 }
3050 
3051 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
3052   guarantee(nm != nullptr, "sanity");
3053   UnregisterNMethodOopClosure reg_cl(this, nm);
3054   nm->oops_do(&reg_cl, true);
3055 }
3056 
3057 void G1CollectedHeap::update_used_after_gc(bool evacuation_failed) {
3058   if (evacuation_failed) {
3059     // Reset the G1EvacuationFailureALot counters and flags
3060     evac_failure_injector()->reset();
3061 
3062     set_used(recalculate_used());
3063   } else {
3064     // The "used" of the collection set have already been subtracted
3065     // when they were freed.  Add in the bytes used.
3066     increase_used(_bytes_used_during_gc);
3067   }
3068 }
3069 
3070 class RebuildCodeRootClosure: public CodeBlobClosure {
3071   G1CollectedHeap* _g1h;
3072 
3073 public:
3074   RebuildCodeRootClosure(G1CollectedHeap* g1h) :
3075     _g1h(g1h) {}
3076 
3077   void do_code_blob(CodeBlob* cb) {
3078     nmethod* nm = cb->as_nmethod_or_null();
3079     if (nm != nullptr) {
3080       _g1h->register_nmethod(nm);
3081     }
3082   }
3083 };
3084 
3085 void G1CollectedHeap::rebuild_code_roots() {
3086   RebuildCodeRootClosure blob_cl(this);
3087   CodeCache::blobs_do(&blob_cl);
3088 }
3089 
3090 void G1CollectedHeap::initialize_serviceability() {
3091   _monitoring_support->initialize_serviceability();
3092 }
3093 
3094 MemoryUsage G1CollectedHeap::memory_usage() {
3095   return _monitoring_support->memory_usage();
3096 }
3097 
3098 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
3099   return _monitoring_support->memory_managers();
3100 }
3101 
3102 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
3103   return _monitoring_support->memory_pools();
3104 }
3105 
3106 void G1CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
3107   HeapRegion* region = heap_region_containing(start);
3108   region->fill_with_dummy_object(start, pointer_delta(end, start), zap);
3109 }
3110 
3111 void G1CollectedHeap::start_codecache_marking_cycle_if_inactive(bool concurrent_mark_start) {
3112   // We can reach here with an active code cache marking cycle either because the
3113   // previous G1 concurrent marking cycle was undone (if heap occupancy after the
3114   // concurrent start young collection was below the threshold) or aborted. See
3115   // CodeCache::on_gc_marking_cycle_finish() why this is.  We must not start a new code
3116   // cache cycle then. If we are about to start a new g1 concurrent marking cycle we
3117   // still have to arm all nmethod entry barriers. They are needed for adding oop
3118   // constants to the SATB snapshot. Full GC does not need nmethods to be armed.
3119   if (!CodeCache::is_gc_marking_cycle_active()) {
3120     CodeCache::on_gc_marking_cycle_start();
3121   }
3122   if (concurrent_mark_start) {
3123     CodeCache::arm_all_nmethods();
3124   }
3125 }
3126 
3127 void G1CollectedHeap::finish_codecache_marking_cycle() {
3128   CodeCache::on_gc_marking_cycle_finish();
3129   CodeCache::arm_all_nmethods();
3130 }