1 /*
   2  * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoaderDataGraph.hpp"
  27 #include "classfile/metadataOnStackMark.hpp"
  28 #include "classfile/stringTable.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "gc/g1/g1Allocator.inline.hpp"
  32 #include "gc/g1/g1BarrierSet.hpp"
  33 #include "gc/g1/g1CollectedHeap.inline.hpp"
  34 #include "gc/g1/g1CollectionSet.hpp"
  35 #include "gc/g1/g1CollectorPolicy.hpp"
  36 #include "gc/g1/g1CollectorState.hpp"
  37 #include "gc/g1/g1ConcurrentRefine.hpp"
  38 #include "gc/g1/g1ConcurrentRefineThread.hpp"
  39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
  40 #include "gc/g1/g1EvacStats.inline.hpp"
  41 #include "gc/g1/g1FullCollector.hpp"
  42 #include "gc/g1/g1GCPhaseTimes.hpp"
  43 #include "gc/g1/g1HeapSizingPolicy.hpp"
  44 #include "gc/g1/g1HeapTransition.hpp"
  45 #include "gc/g1/g1HeapVerifier.hpp"
  46 #include "gc/g1/g1HotCardCache.hpp"
  47 #include "gc/g1/g1MemoryPool.hpp"
  48 #include "gc/g1/g1OopClosures.inline.hpp"
  49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  50 #include "gc/g1/g1Policy.hpp"
  51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  52 #include "gc/g1/g1RemSet.hpp"
  53 #include "gc/g1/g1RootClosures.hpp"
  54 #include "gc/g1/g1RootProcessor.hpp"
  55 #include "gc/g1/g1SATBMarkQueueSet.hpp"
  56 #include "gc/g1/g1StringDedup.hpp"
  57 #include "gc/g1/g1ThreadLocalData.hpp"
  58 #include "gc/g1/g1YCTypes.hpp"
  59 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  60 #include "gc/g1/heapRegion.inline.hpp"
  61 #include "gc/g1/heapRegionRemSet.hpp"
  62 #include "gc/g1/heapRegionSet.inline.hpp"
  63 #include "gc/g1/vm_operations_g1.hpp"
  64 #include "gc/shared/adaptiveSizePolicy.hpp"
  65 #include "gc/shared/gcHeapSummary.hpp"
  66 #include "gc/shared/gcId.hpp"
  67 #include "gc/shared/gcLocker.hpp"
  68 #include "gc/shared/gcTimer.hpp"
  69 #include "gc/shared/gcTrace.hpp"
  70 #include "gc/shared/gcTraceTime.inline.hpp"
  71 #include "gc/shared/generationSpec.hpp"
  72 #include "gc/shared/isGCActiveMark.hpp"
  73 #include "gc/shared/oopStorageParState.hpp"
  74 #include "gc/shared/parallelCleaning.hpp"
  75 #include "gc/shared/preservedMarks.inline.hpp"
  76 #include "gc/shared/suspendibleThreadSet.hpp"
  77 #include "gc/shared/referenceProcessor.inline.hpp"
  78 #include "gc/shared/taskqueue.inline.hpp"
  79 #include "gc/shared/weakProcessor.inline.hpp"
  80 #include "logging/log.hpp"
  81 #include "memory/allocation.hpp"
  82 #include "memory/iterator.hpp"
  83 #include "memory/metaspaceShared.inline.hpp"
  84 #include "memory/resourceArea.hpp"
  85 #include "oops/access.inline.hpp"
  86 #include "oops/compressedOops.inline.hpp"
  87 #include "oops/oop.inline.hpp"
  88 #include "runtime/atomic.hpp"
  89 #include "runtime/flags/flagSetting.hpp"
  90 #include "runtime/handles.inline.hpp"
  91 #include "runtime/init.hpp"
  92 #include "runtime/orderAccess.hpp"
  93 #include "runtime/threadSMR.hpp"
  94 #include "runtime/vmThread.hpp"
  95 #include "utilities/align.hpp"
  96 #include "utilities/globalDefinitions.hpp"
  97 #include "utilities/stack.inline.hpp"
  98 
  99 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
 100 
 101 // INVARIANTS/NOTES
 102 //
 103 // All allocation activity covered by the G1CollectedHeap interface is
 104 // serialized by acquiring the HeapLock.  This happens in mem_allocate
 105 // and allocate_new_tlab, which are the "entry" points to the
 106 // allocation code from the rest of the JVM.  (Note that this does not
 107 // apply to TLAB allocation, which is not part of this interface: it
 108 // is done by clients of this interface.)
 109 
 110 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 111  private:
 112   size_t _num_dirtied;
 113   G1CollectedHeap* _g1h;
 114   G1CardTable* _g1_ct;
 115 
 116   HeapRegion* region_for_card(jbyte* card_ptr) const {
 117     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
 118   }
 119 
 120   bool will_become_free(HeapRegion* hr) const {
 121     // A region will be freed by free_collection_set if the region is in the
 122     // collection set and has not had an evacuation failure.
 123     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 124   }
 125 
 126  public:
 127   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 128     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
 129 
 130   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 131     HeapRegion* hr = region_for_card(card_ptr);
 132 
 133     // Should only dirty cards in regions that won't be freed.
 134     if (!will_become_free(hr)) {
 135       *card_ptr = G1CardTable::dirty_card_val();
 136       _num_dirtied++;
 137     }
 138 
 139     return true;
 140   }
 141 
 142   size_t num_dirtied()   const { return _num_dirtied; }
 143 };
 144 
 145 
 146 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 147   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 148 }
 149 
 150 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 151   // The from card cache is not the memory that is actually committed. So we cannot
 152   // take advantage of the zero_filled parameter.
 153   reset_from_card_cache(start_idx, num_regions);
 154 }
 155 
 156 
 157 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 158                                              MemRegion mr) {
 159   return new HeapRegion(hrs_index, bot(), mr);
 160 }
 161 
 162 // Private methods.
 163 
 164 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 165   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 166          "the only time we use this to allocate a humongous region is "
 167          "when we are allocating a single humongous region");
 168 
 169   HeapRegion* res = _hrm.allocate_free_region(is_old);
 170 
 171   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 172     // Currently, only attempts to allocate GC alloc regions set
 173     // do_expand to true. So, we should only reach here during a
 174     // safepoint. If this assumption changes we might have to
 175     // reconsider the use of _expand_heap_after_alloc_failure.
 176     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 177 
 178     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 179                               word_size * HeapWordSize);
 180 
 181     if (expand(word_size * HeapWordSize)) {
 182       // Given that expand() succeeded in expanding the heap, and we
 183       // always expand the heap by an amount aligned to the heap
 184       // region size, the free list should in theory not be empty.
 185       // In either case allocate_free_region() will check for NULL.
 186       res = _hrm.allocate_free_region(is_old);
 187     } else {
 188       _expand_heap_after_alloc_failure = false;
 189     }
 190   }
 191   return res;
 192 }
 193 
 194 HeapWord*
 195 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 196                                                            uint num_regions,
 197                                                            size_t word_size) {
 198   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 199   assert(is_humongous(word_size), "word_size should be humongous");
 200   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 201 
 202   // Index of last region in the series.
 203   uint last = first + num_regions - 1;
 204 
 205   // We need to initialize the region(s) we just discovered. This is
 206   // a bit tricky given that it can happen concurrently with
 207   // refinement threads refining cards on these regions and
 208   // potentially wanting to refine the BOT as they are scanning
 209   // those cards (this can happen shortly after a cleanup; see CR
 210   // 6991377). So we have to set up the region(s) carefully and in
 211   // a specific order.
 212 
 213   // The word size sum of all the regions we will allocate.
 214   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 215   assert(word_size <= word_size_sum, "sanity");
 216 
 217   // This will be the "starts humongous" region.
 218   HeapRegion* first_hr = region_at(first);
 219   // The header of the new object will be placed at the bottom of
 220   // the first region.
 221   HeapWord* new_obj = first_hr->bottom();
 222   // This will be the new top of the new object.
 223   HeapWord* obj_top = new_obj + word_size;
 224 
 225   // First, we need to zero the header of the space that we will be
 226   // allocating. When we update top further down, some refinement
 227   // threads might try to scan the region. By zeroing the header we
 228   // ensure that any thread that will try to scan the region will
 229   // come across the zero klass word and bail out.
 230   //
 231   // NOTE: It would not have been correct to have used
 232   // CollectedHeap::fill_with_object() and make the space look like
 233   // an int array. The thread that is doing the allocation will
 234   // later update the object header to a potentially different array
 235   // type and, for a very short period of time, the klass and length
 236   // fields will be inconsistent. This could cause a refinement
 237   // thread to calculate the object size incorrectly.
 238   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 239 
 240   // Next, pad out the unused tail of the last region with filler
 241   // objects, for improved usage accounting.
 242   // How many words we use for filler objects.
 243   size_t word_fill_size = word_size_sum - word_size;
 244 
 245   // How many words memory we "waste" which cannot hold a filler object.
 246   size_t words_not_fillable = 0;
 247 
 248   if (word_fill_size >= min_fill_size()) {
 249     fill_with_objects(obj_top, word_fill_size);
 250   } else if (word_fill_size > 0) {
 251     // We have space to fill, but we cannot fit an object there.
 252     words_not_fillable = word_fill_size;
 253     word_fill_size = 0;
 254   }
 255 
 256   // We will set up the first region as "starts humongous". This
 257   // will also update the BOT covering all the regions to reflect
 258   // that there is a single object that starts at the bottom of the
 259   // first region.
 260   first_hr->set_starts_humongous(obj_top, word_fill_size);
 261   _g1_policy->remset_tracker()->update_at_allocate(first_hr);
 262   // Then, if there are any, we will set up the "continues
 263   // humongous" regions.
 264   HeapRegion* hr = NULL;
 265   for (uint i = first + 1; i <= last; ++i) {
 266     hr = region_at(i);
 267     hr->set_continues_humongous(first_hr);
 268     _g1_policy->remset_tracker()->update_at_allocate(hr);
 269   }
 270 
 271   // Up to this point no concurrent thread would have been able to
 272   // do any scanning on any region in this series. All the top
 273   // fields still point to bottom, so the intersection between
 274   // [bottom,top] and [card_start,card_end] will be empty. Before we
 275   // update the top fields, we'll do a storestore to make sure that
 276   // no thread sees the update to top before the zeroing of the
 277   // object header and the BOT initialization.
 278   OrderAccess::storestore();
 279 
 280   // Now, we will update the top fields of the "continues humongous"
 281   // regions except the last one.
 282   for (uint i = first; i < last; ++i) {
 283     hr = region_at(i);
 284     hr->set_top(hr->end());
 285   }
 286 
 287   hr = region_at(last);
 288   // If we cannot fit a filler object, we must set top to the end
 289   // of the humongous object, otherwise we cannot iterate the heap
 290   // and the BOT will not be complete.
 291   hr->set_top(hr->end() - words_not_fillable);
 292 
 293   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 294          "obj_top should be in last region");
 295 
 296   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 297 
 298   assert(words_not_fillable == 0 ||
 299          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 300          "Miscalculation in humongous allocation");
 301 
 302   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 303 
 304   for (uint i = first; i <= last; ++i) {
 305     hr = region_at(i);
 306     _humongous_set.add(hr);
 307     _hr_printer.alloc(hr);
 308   }
 309 
 310   return new_obj;
 311 }
 312 
 313 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 314   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 315   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 316 }
 317 
 318 // If could fit into free regions w/o expansion, try.
 319 // Otherwise, if can expand, do so.
 320 // Otherwise, if using ex regions might help, try with ex given back.
 321 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 322   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 323 
 324   _verifier->verify_region_sets_optional();
 325 
 326   uint first = G1_NO_HRM_INDEX;
 327   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 328 
 329   if (obj_regions == 1) {
 330     // Only one region to allocate, try to use a fast path by directly allocating
 331     // from the free lists. Do not try to expand here, we will potentially do that
 332     // later.
 333     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 334     if (hr != NULL) {
 335       first = hr->hrm_index();
 336     }
 337   } else {
 338     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 339     // are lucky enough to find some.
 340     first = _hrm.find_contiguous_only_empty(obj_regions);
 341     if (first != G1_NO_HRM_INDEX) {
 342       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 343     }
 344   }
 345 
 346   if (first == G1_NO_HRM_INDEX) {
 347     // Policy: We could not find enough regions for the humongous object in the
 348     // free list. Look through the heap to find a mix of free and uncommitted regions.
 349     // If so, try expansion.
 350     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 351     if (first != G1_NO_HRM_INDEX) {
 352       // We found something. Make sure these regions are committed, i.e. expand
 353       // the heap. Alternatively we could do a defragmentation GC.
 354       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 355                                     word_size * HeapWordSize);
 356 
 357       _hrm.expand_at(first, obj_regions, workers());
 358       g1_policy()->record_new_heap_size(num_regions());
 359 
 360 #ifdef ASSERT
 361       for (uint i = first; i < first + obj_regions; ++i) {
 362         HeapRegion* hr = region_at(i);
 363         assert(hr->is_free(), "sanity");
 364         assert(hr->is_empty(), "sanity");
 365         assert(is_on_master_free_list(hr), "sanity");
 366       }
 367 #endif
 368       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 369     } else {
 370       // Policy: Potentially trigger a defragmentation GC.
 371     }
 372   }
 373 
 374   HeapWord* result = NULL;
 375   if (first != G1_NO_HRM_INDEX) {
 376     result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
 377     assert(result != NULL, "it should always return a valid result");
 378 
 379     // A successful humongous object allocation changes the used space
 380     // information of the old generation so we need to recalculate the
 381     // sizes and update the jstat counters here.
 382     g1mm()->update_sizes();
 383   }
 384 
 385   _verifier->verify_region_sets_optional();
 386 
 387   return result;
 388 }
 389 
 390 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
 391                                              size_t requested_size,
 392                                              size_t* actual_size) {
 393   assert_heap_not_locked_and_not_at_safepoint();
 394   assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
 395 
 396   return attempt_allocation(min_size, requested_size, actual_size);
 397 }
 398 
 399 HeapWord*
 400 G1CollectedHeap::mem_allocate(size_t word_size,
 401                               bool*  gc_overhead_limit_was_exceeded) {
 402   assert_heap_not_locked_and_not_at_safepoint();
 403 
 404   if (is_humongous(word_size)) {
 405     return attempt_allocation_humongous(word_size);
 406   }
 407   size_t dummy = 0;
 408   return attempt_allocation(word_size, word_size, &dummy);
 409 }
 410 
 411 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 412   ResourceMark rm; // For retrieving the thread names in log messages.
 413 
 414   // Make sure you read the note in attempt_allocation_humongous().
 415 
 416   assert_heap_not_locked_and_not_at_safepoint();
 417   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 418          "be called for humongous allocation requests");
 419 
 420   // We should only get here after the first-level allocation attempt
 421   // (attempt_allocation()) failed to allocate.
 422 
 423   // We will loop until a) we manage to successfully perform the
 424   // allocation or b) we successfully schedule a collection which
 425   // fails to perform the allocation. b) is the only case when we'll
 426   // return NULL.
 427   HeapWord* result = NULL;
 428   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 429     bool should_try_gc;
 430     uint gc_count_before;
 431 
 432     {
 433       MutexLockerEx x(Heap_lock);
 434       result = _allocator->attempt_allocation_locked(word_size);
 435       if (result != NULL) {
 436         return result;
 437       }
 438 
 439       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 440       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 441       // waiting because the GCLocker is active to not wait too long.
 442       if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
 443         // No need for an ergo message here, can_expand_young_list() does this when
 444         // it returns true.
 445         result = _allocator->attempt_allocation_force(word_size);
 446         if (result != NULL) {
 447           return result;
 448         }
 449       }
 450       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 451       // the GCLocker initiated GC has been performed and then retry. This includes
 452       // the case when the GC Locker is not active but has not been performed.
 453       should_try_gc = !GCLocker::needs_gc();
 454       // Read the GC count while still holding the Heap_lock.
 455       gc_count_before = total_collections();
 456     }
 457 
 458     if (should_try_gc) {
 459       bool succeeded;
 460       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 461                                    GCCause::_g1_inc_collection_pause);
 462       if (result != NULL) {
 463         assert(succeeded, "only way to get back a non-NULL result");
 464         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 465                              Thread::current()->name(), p2i(result));
 466         return result;
 467       }
 468 
 469       if (succeeded) {
 470         // We successfully scheduled a collection which failed to allocate. No
 471         // point in trying to allocate further. We'll just return NULL.
 472         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 473                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 474         return NULL;
 475       }
 476       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 477                            Thread::current()->name(), word_size);
 478     } else {
 479       // Failed to schedule a collection.
 480       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 481         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 482                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 483         return NULL;
 484       }
 485       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 486       // The GCLocker is either active or the GCLocker initiated
 487       // GC has not yet been performed. Stall until it is and
 488       // then retry the allocation.
 489       GCLocker::stall_until_clear();
 490       gclocker_retry_count += 1;
 491     }
 492 
 493     // We can reach here if we were unsuccessful in scheduling a
 494     // collection (because another thread beat us to it) or if we were
 495     // stalled due to the GC locker. In either can we should retry the
 496     // allocation attempt in case another thread successfully
 497     // performed a collection and reclaimed enough space. We do the
 498     // first attempt (without holding the Heap_lock) here and the
 499     // follow-on attempt will be at the start of the next loop
 500     // iteration (after taking the Heap_lock).
 501     size_t dummy = 0;
 502     result = _allocator->attempt_allocation(word_size, word_size, &dummy);
 503     if (result != NULL) {
 504       return result;
 505     }
 506 
 507     // Give a warning if we seem to be looping forever.
 508     if ((QueuedAllocationWarningCount > 0) &&
 509         (try_count % QueuedAllocationWarningCount == 0)) {
 510       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 511                              Thread::current()->name(), try_count, word_size);
 512     }
 513   }
 514 
 515   ShouldNotReachHere();
 516   return NULL;
 517 }
 518 
 519 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 520   assert_at_safepoint_on_vm_thread();
 521   if (_archive_allocator == NULL) {
 522     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 523   }
 524 }
 525 
 526 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 527   // Allocations in archive regions cannot be of a size that would be considered
 528   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 529   // may be different at archive-restore time.
 530   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 531 }
 532 
 533 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 534   assert_at_safepoint_on_vm_thread();
 535   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 536   if (is_archive_alloc_too_large(word_size)) {
 537     return NULL;
 538   }
 539   return _archive_allocator->archive_mem_allocate(word_size);
 540 }
 541 
 542 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 543                                               size_t end_alignment_in_bytes) {
 544   assert_at_safepoint_on_vm_thread();
 545   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 546 
 547   // Call complete_archive to do the real work, filling in the MemRegion
 548   // array with the archive regions.
 549   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 550   delete _archive_allocator;
 551   _archive_allocator = NULL;
 552 }
 553 
 554 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 555   assert(ranges != NULL, "MemRegion array NULL");
 556   assert(count != 0, "No MemRegions provided");
 557   MemRegion reserved = _hrm.reserved();
 558   for (size_t i = 0; i < count; i++) {
 559     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 560       return false;
 561     }
 562   }
 563   return true;
 564 }
 565 
 566 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 567                                             size_t count,
 568                                             bool open) {
 569   assert(!is_init_completed(), "Expect to be called at JVM init time");
 570   assert(ranges != NULL, "MemRegion array NULL");
 571   assert(count != 0, "No MemRegions provided");
 572   MutexLockerEx x(Heap_lock);
 573 
 574   MemRegion reserved = _hrm.reserved();
 575   HeapWord* prev_last_addr = NULL;
 576   HeapRegion* prev_last_region = NULL;
 577 
 578   // Temporarily disable pretouching of heap pages. This interface is used
 579   // when mmap'ing archived heap data in, so pre-touching is wasted.
 580   FlagSetting fs(AlwaysPreTouch, false);
 581 
 582   // Enable archive object checking used by G1MarkSweep. We have to let it know
 583   // about each archive range, so that objects in those ranges aren't marked.
 584   G1ArchiveAllocator::enable_archive_object_check();
 585 
 586   // For each specified MemRegion range, allocate the corresponding G1
 587   // regions and mark them as archive regions. We expect the ranges
 588   // in ascending starting address order, without overlap.
 589   for (size_t i = 0; i < count; i++) {
 590     MemRegion curr_range = ranges[i];
 591     HeapWord* start_address = curr_range.start();
 592     size_t word_size = curr_range.word_size();
 593     HeapWord* last_address = curr_range.last();
 594     size_t commits = 0;
 595 
 596     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 597               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 598               p2i(start_address), p2i(last_address));
 599     guarantee(start_address > prev_last_addr,
 600               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 601               p2i(start_address), p2i(prev_last_addr));
 602     prev_last_addr = last_address;
 603 
 604     // Check for ranges that start in the same G1 region in which the previous
 605     // range ended, and adjust the start address so we don't try to allocate
 606     // the same region again. If the current range is entirely within that
 607     // region, skip it, just adjusting the recorded top.
 608     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 609     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 610       start_address = start_region->end();
 611       if (start_address > last_address) {
 612         increase_used(word_size * HeapWordSize);
 613         start_region->set_top(last_address + 1);
 614         continue;
 615       }
 616       start_region->set_top(start_address);
 617       curr_range = MemRegion(start_address, last_address + 1);
 618       start_region = _hrm.addr_to_region(start_address);
 619     }
 620 
 621     // Perform the actual region allocation, exiting if it fails.
 622     // Then note how much new space we have allocated.
 623     if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
 624       return false;
 625     }
 626     increase_used(word_size * HeapWordSize);
 627     if (commits != 0) {
 628       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 629                                 HeapRegion::GrainWords * HeapWordSize * commits);
 630 
 631     }
 632 
 633     // Mark each G1 region touched by the range as archive, add it to
 634     // the old set, and set top.
 635     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 636     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 637     prev_last_region = last_region;
 638 
 639     while (curr_region != NULL) {
 640       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 641              "Region already in use (index %u)", curr_region->hrm_index());
 642       if (open) {
 643         curr_region->set_open_archive();
 644       } else {
 645         curr_region->set_closed_archive();
 646       }
 647       _hr_printer.alloc(curr_region);
 648       _archive_set.add(curr_region);
 649       HeapWord* top;
 650       HeapRegion* next_region;
 651       if (curr_region != last_region) {
 652         top = curr_region->end();
 653         next_region = _hrm.next_region_in_heap(curr_region);
 654       } else {
 655         top = last_address + 1;
 656         next_region = NULL;
 657       }
 658       curr_region->set_top(top);
 659       curr_region->set_first_dead(top);
 660       curr_region->set_end_of_live(top);
 661       curr_region = next_region;
 662     }
 663 
 664     // Notify mark-sweep of the archive
 665     G1ArchiveAllocator::set_range_archive(curr_range, open);
 666   }
 667   return true;
 668 }
 669 
 670 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 671   assert(!is_init_completed(), "Expect to be called at JVM init time");
 672   assert(ranges != NULL, "MemRegion array NULL");
 673   assert(count != 0, "No MemRegions provided");
 674   MemRegion reserved = _hrm.reserved();
 675   HeapWord *prev_last_addr = NULL;
 676   HeapRegion* prev_last_region = NULL;
 677 
 678   // For each MemRegion, create filler objects, if needed, in the G1 regions
 679   // that contain the address range. The address range actually within the
 680   // MemRegion will not be modified. That is assumed to have been initialized
 681   // elsewhere, probably via an mmap of archived heap data.
 682   MutexLockerEx x(Heap_lock);
 683   for (size_t i = 0; i < count; i++) {
 684     HeapWord* start_address = ranges[i].start();
 685     HeapWord* last_address = ranges[i].last();
 686 
 687     assert(reserved.contains(start_address) && reserved.contains(last_address),
 688            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 689            p2i(start_address), p2i(last_address));
 690     assert(start_address > prev_last_addr,
 691            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 692            p2i(start_address), p2i(prev_last_addr));
 693 
 694     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 695     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 696     HeapWord* bottom_address = start_region->bottom();
 697 
 698     // Check for a range beginning in the same region in which the
 699     // previous one ended.
 700     if (start_region == prev_last_region) {
 701       bottom_address = prev_last_addr + 1;
 702     }
 703 
 704     // Verify that the regions were all marked as archive regions by
 705     // alloc_archive_regions.
 706     HeapRegion* curr_region = start_region;
 707     while (curr_region != NULL) {
 708       guarantee(curr_region->is_archive(),
 709                 "Expected archive region at index %u", curr_region->hrm_index());
 710       if (curr_region != last_region) {
 711         curr_region = _hrm.next_region_in_heap(curr_region);
 712       } else {
 713         curr_region = NULL;
 714       }
 715     }
 716 
 717     prev_last_addr = last_address;
 718     prev_last_region = last_region;
 719 
 720     // Fill the memory below the allocated range with dummy object(s),
 721     // if the region bottom does not match the range start, or if the previous
 722     // range ended within the same G1 region, and there is a gap.
 723     if (start_address != bottom_address) {
 724       size_t fill_size = pointer_delta(start_address, bottom_address);
 725       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 726       increase_used(fill_size * HeapWordSize);
 727     }
 728   }
 729 }
 730 
 731 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
 732                                                      size_t desired_word_size,
 733                                                      size_t* actual_word_size) {
 734   assert_heap_not_locked_and_not_at_safepoint();
 735   assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
 736          "be called for humongous allocation requests");
 737 
 738   HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
 739 
 740   if (result == NULL) {
 741     *actual_word_size = desired_word_size;
 742     result = attempt_allocation_slow(desired_word_size);
 743   }
 744 
 745   assert_heap_not_locked();
 746   if (result != NULL) {
 747     assert(*actual_word_size != 0, "Actual size must have been set here");
 748     dirty_young_block(result, *actual_word_size);
 749   } else {
 750     *actual_word_size = 0;
 751   }
 752 
 753   return result;
 754 }
 755 
 756 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 757   assert(!is_init_completed(), "Expect to be called at JVM init time");
 758   assert(ranges != NULL, "MemRegion array NULL");
 759   assert(count != 0, "No MemRegions provided");
 760   MemRegion reserved = _hrm.reserved();
 761   HeapWord* prev_last_addr = NULL;
 762   HeapRegion* prev_last_region = NULL;
 763   size_t size_used = 0;
 764   size_t uncommitted_regions = 0;
 765 
 766   // For each Memregion, free the G1 regions that constitute it, and
 767   // notify mark-sweep that the range is no longer to be considered 'archive.'
 768   MutexLockerEx x(Heap_lock);
 769   for (size_t i = 0; i < count; i++) {
 770     HeapWord* start_address = ranges[i].start();
 771     HeapWord* last_address = ranges[i].last();
 772 
 773     assert(reserved.contains(start_address) && reserved.contains(last_address),
 774            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 775            p2i(start_address), p2i(last_address));
 776     assert(start_address > prev_last_addr,
 777            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 778            p2i(start_address), p2i(prev_last_addr));
 779     size_used += ranges[i].byte_size();
 780     prev_last_addr = last_address;
 781 
 782     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 783     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 784 
 785     // Check for ranges that start in the same G1 region in which the previous
 786     // range ended, and adjust the start address so we don't try to free
 787     // the same region again. If the current range is entirely within that
 788     // region, skip it.
 789     if (start_region == prev_last_region) {
 790       start_address = start_region->end();
 791       if (start_address > last_address) {
 792         continue;
 793       }
 794       start_region = _hrm.addr_to_region(start_address);
 795     }
 796     prev_last_region = last_region;
 797 
 798     // After verifying that each region was marked as an archive region by
 799     // alloc_archive_regions, set it free and empty and uncommit it.
 800     HeapRegion* curr_region = start_region;
 801     while (curr_region != NULL) {
 802       guarantee(curr_region->is_archive(),
 803                 "Expected archive region at index %u", curr_region->hrm_index());
 804       uint curr_index = curr_region->hrm_index();
 805       _archive_set.remove(curr_region);
 806       curr_region->set_free();
 807       curr_region->set_top(curr_region->bottom());
 808       if (curr_region != last_region) {
 809         curr_region = _hrm.next_region_in_heap(curr_region);
 810       } else {
 811         curr_region = NULL;
 812       }
 813       _hrm.shrink_at(curr_index, 1);
 814       uncommitted_regions++;
 815     }
 816 
 817     // Notify mark-sweep that this is no longer an archive range.
 818     G1ArchiveAllocator::set_range_archive(ranges[i], false);
 819   }
 820 
 821   if (uncommitted_regions != 0) {
 822     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 823                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 824   }
 825   decrease_used(size_used);
 826 }
 827 
 828 oop G1CollectedHeap::materialize_archived_object(oop obj) {
 829   assert(obj != NULL, "archived obj is NULL");
 830   assert(MetaspaceShared::is_archive_object(obj), "must be archived object");
 831 
 832   // Loading an archived object makes it strongly reachable. If it is
 833   // loaded during concurrent marking, it must be enqueued to the SATB
 834   // queue, shading the previously white object gray.
 835   G1BarrierSet::enqueue(obj);
 836 
 837   return obj;
 838 }
 839 
 840 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 841   ResourceMark rm; // For retrieving the thread names in log messages.
 842 
 843   // The structure of this method has a lot of similarities to
 844   // attempt_allocation_slow(). The reason these two were not merged
 845   // into a single one is that such a method would require several "if
 846   // allocation is not humongous do this, otherwise do that"
 847   // conditional paths which would obscure its flow. In fact, an early
 848   // version of this code did use a unified method which was harder to
 849   // follow and, as a result, it had subtle bugs that were hard to
 850   // track down. So keeping these two methods separate allows each to
 851   // be more readable. It will be good to keep these two in sync as
 852   // much as possible.
 853 
 854   assert_heap_not_locked_and_not_at_safepoint();
 855   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 856          "should only be called for humongous allocations");
 857 
 858   // Humongous objects can exhaust the heap quickly, so we should check if we
 859   // need to start a marking cycle at each humongous object allocation. We do
 860   // the check before we do the actual allocation. The reason for doing it
 861   // before the allocation is that we avoid having to keep track of the newly
 862   // allocated memory while we do a GC.
 863   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 864                                            word_size)) {
 865     collect(GCCause::_g1_humongous_allocation);
 866   }
 867 
 868   // We will loop until a) we manage to successfully perform the
 869   // allocation or b) we successfully schedule a collection which
 870   // fails to perform the allocation. b) is the only case when we'll
 871   // return NULL.
 872   HeapWord* result = NULL;
 873   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 874     bool should_try_gc;
 875     uint gc_count_before;
 876 
 877 
 878     {
 879       MutexLockerEx x(Heap_lock);
 880 
 881       // Given that humongous objects are not allocated in young
 882       // regions, we'll first try to do the allocation without doing a
 883       // collection hoping that there's enough space in the heap.
 884       result = humongous_obj_allocate(word_size);
 885       if (result != NULL) {
 886         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 887         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 888         return result;
 889       }
 890 
 891       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 892       // the GCLocker initiated GC has been performed and then retry. This includes
 893       // the case when the GC Locker is not active but has not been performed.
 894       should_try_gc = !GCLocker::needs_gc();
 895       // Read the GC count while still holding the Heap_lock.
 896       gc_count_before = total_collections();
 897     }
 898 
 899     if (should_try_gc) {
 900       bool succeeded;
 901       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 902                                    GCCause::_g1_humongous_allocation);
 903       if (result != NULL) {
 904         assert(succeeded, "only way to get back a non-NULL result");
 905         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 906                              Thread::current()->name(), p2i(result));
 907         return result;
 908       }
 909 
 910       if (succeeded) {
 911         // We successfully scheduled a collection which failed to allocate. No
 912         // point in trying to allocate further. We'll just return NULL.
 913         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 914                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 915         return NULL;
 916       }
 917       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 918                            Thread::current()->name(), word_size);
 919     } else {
 920       // Failed to schedule a collection.
 921       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 922         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 923                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 924         return NULL;
 925       }
 926       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 927       // The GCLocker is either active or the GCLocker initiated
 928       // GC has not yet been performed. Stall until it is and
 929       // then retry the allocation.
 930       GCLocker::stall_until_clear();
 931       gclocker_retry_count += 1;
 932     }
 933 
 934 
 935     // We can reach here if we were unsuccessful in scheduling a
 936     // collection (because another thread beat us to it) or if we were
 937     // stalled due to the GC locker. In either can we should retry the
 938     // allocation attempt in case another thread successfully
 939     // performed a collection and reclaimed enough space.
 940     // Humongous object allocation always needs a lock, so we wait for the retry
 941     // in the next iteration of the loop, unlike for the regular iteration case.
 942     // Give a warning if we seem to be looping forever.
 943 
 944     if ((QueuedAllocationWarningCount > 0) &&
 945         (try_count % QueuedAllocationWarningCount == 0)) {
 946       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 947                              Thread::current()->name(), try_count, word_size);
 948     }
 949   }
 950 
 951   ShouldNotReachHere();
 952   return NULL;
 953 }
 954 
 955 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 956                                                            bool expect_null_mutator_alloc_region) {
 957   assert_at_safepoint_on_vm_thread();
 958   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 959          "the current alloc region was unexpectedly found to be non-NULL");
 960 
 961   if (!is_humongous(word_size)) {
 962     return _allocator->attempt_allocation_locked(word_size);
 963   } else {
 964     HeapWord* result = humongous_obj_allocate(word_size);
 965     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
 966       collector_state()->set_initiate_conc_mark_if_possible(true);
 967     }
 968     return result;
 969   }
 970 
 971   ShouldNotReachHere();
 972 }
 973 
 974 class PostCompactionPrinterClosure: public HeapRegionClosure {
 975 private:
 976   G1HRPrinter* _hr_printer;
 977 public:
 978   bool do_heap_region(HeapRegion* hr) {
 979     assert(!hr->is_young(), "not expecting to find young regions");
 980     _hr_printer->post_compaction(hr);
 981     return false;
 982   }
 983 
 984   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 985     : _hr_printer(hr_printer) { }
 986 };
 987 
 988 void G1CollectedHeap::print_hrm_post_compaction() {
 989   if (_hr_printer.is_active()) {
 990     PostCompactionPrinterClosure cl(hr_printer());
 991     heap_region_iterate(&cl);
 992   }
 993 }
 994 
 995 void G1CollectedHeap::abort_concurrent_cycle() {
 996   // If we start the compaction before the CM threads finish
 997   // scanning the root regions we might trip them over as we'll
 998   // be moving objects / updating references. So let's wait until
 999   // they are done. By telling them to abort, they should complete
1000   // early.
1001   _cm->root_regions()->abort();
1002   _cm->root_regions()->wait_until_scan_finished();
1003 
1004   // Disable discovery and empty the discovered lists
1005   // for the CM ref processor.
1006   _ref_processor_cm->disable_discovery();
1007   _ref_processor_cm->abandon_partial_discovery();
1008   _ref_processor_cm->verify_no_references_recorded();
1009 
1010   // Abandon current iterations of concurrent marking and concurrent
1011   // refinement, if any are in progress.
1012   concurrent_mark()->concurrent_cycle_abort();
1013 }
1014 
1015 void G1CollectedHeap::prepare_heap_for_full_collection() {
1016   // Make sure we'll choose a new allocation region afterwards.
1017   _allocator->release_mutator_alloc_region();
1018   _allocator->abandon_gc_alloc_regions();
1019   g1_rem_set()->cleanupHRRS();
1020 
1021   // We may have added regions to the current incremental collection
1022   // set between the last GC or pause and now. We need to clear the
1023   // incremental collection set and then start rebuilding it afresh
1024   // after this full GC.
1025   abandon_collection_set(collection_set());
1026 
1027   tear_down_region_sets(false /* free_list_only */);
1028 }
1029 
1030 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1031   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1032   assert(used() == recalculate_used(), "Should be equal");
1033   _verifier->verify_region_sets_optional();
1034   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1035   _verifier->check_bitmaps("Full GC Start");
1036 }
1037 
1038 void G1CollectedHeap::prepare_heap_for_mutators() {
1039   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1040   ClassLoaderDataGraph::purge();
1041   MetaspaceUtils::verify_metrics();
1042 
1043   // Prepare heap for normal collections.
1044   assert(num_free_regions() == 0, "we should not have added any free regions");
1045   rebuild_region_sets(false /* free_list_only */);
1046   abort_refinement();
1047   resize_if_necessary_after_full_collection();
1048 
1049   // Rebuild the strong code root lists for each region
1050   rebuild_strong_code_roots();
1051 
1052   // Start a new incremental collection set for the next pause
1053   start_new_collection_set();
1054 
1055   _allocator->init_mutator_alloc_region();
1056 
1057   // Post collection state updates.
1058   MetaspaceGC::compute_new_size();
1059 }
1060 
1061 void G1CollectedHeap::abort_refinement() {
1062   if (_hot_card_cache->use_cache()) {
1063     _hot_card_cache->reset_hot_cache();
1064   }
1065 
1066   // Discard all remembered set updates.
1067   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1068   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1069 }
1070 
1071 void G1CollectedHeap::verify_after_full_collection() {
1072   _hrm.verify_optional();
1073   _verifier->verify_region_sets_optional();
1074   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1075   // Clear the previous marking bitmap, if needed for bitmap verification.
1076   // Note we cannot do this when we clear the next marking bitmap in
1077   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1078   // objects marked during a full GC against the previous bitmap.
1079   // But we need to clear it before calling check_bitmaps below since
1080   // the full GC has compacted objects and updated TAMS but not updated
1081   // the prev bitmap.
1082   if (G1VerifyBitmaps) {
1083     GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification");
1084     _cm->clear_prev_bitmap(workers());
1085   }
1086   // This call implicitly verifies that the next bitmap is clear after Full GC.
1087   _verifier->check_bitmaps("Full GC End");
1088 
1089   // At this point there should be no regions in the
1090   // entire heap tagged as young.
1091   assert(check_young_list_empty(), "young list should be empty at this point");
1092 
1093   // Note: since we've just done a full GC, concurrent
1094   // marking is no longer active. Therefore we need not
1095   // re-enable reference discovery for the CM ref processor.
1096   // That will be done at the start of the next marking cycle.
1097   // We also know that the STW processor should no longer
1098   // discover any new references.
1099   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1100   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1101   _ref_processor_stw->verify_no_references_recorded();
1102   _ref_processor_cm->verify_no_references_recorded();
1103 }
1104 
1105 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1106   // Post collection logging.
1107   // We should do this after we potentially resize the heap so
1108   // that all the COMMIT / UNCOMMIT events are generated before
1109   // the compaction events.
1110   print_hrm_post_compaction();
1111   heap_transition->print();
1112   print_heap_after_gc();
1113   print_heap_regions();
1114 #ifdef TRACESPINNING
1115   ParallelTaskTerminator::print_termination_counts();
1116 #endif
1117 }
1118 
1119 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1120                                          bool clear_all_soft_refs) {
1121   assert_at_safepoint_on_vm_thread();
1122 
1123   if (GCLocker::check_active_before_gc()) {
1124     // Full GC was not completed.
1125     return false;
1126   }
1127 
1128   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1129       soft_ref_policy()->should_clear_all_soft_refs();
1130 
1131   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1132   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1133 
1134   collector.prepare_collection();
1135   collector.collect();
1136   collector.complete_collection();
1137 
1138   // Full collection was successfully completed.
1139   return true;
1140 }
1141 
1142 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1143   // Currently, there is no facility in the do_full_collection(bool) API to notify
1144   // the caller that the collection did not succeed (e.g., because it was locked
1145   // out by the GC locker). So, right now, we'll ignore the return value.
1146   bool dummy = do_full_collection(true,                /* explicit_gc */
1147                                   clear_all_soft_refs);
1148 }
1149 
1150 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1151   // Capacity, free and used after the GC counted as full regions to
1152   // include the waste in the following calculations.
1153   const size_t capacity_after_gc = capacity();
1154   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1155 
1156   // This is enforced in arguments.cpp.
1157   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1158          "otherwise the code below doesn't make sense");
1159 
1160   // We don't have floating point command-line arguments
1161   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1162   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1163   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1164   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1165 
1166   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1167   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1168 
1169   // We have to be careful here as these two calculations can overflow
1170   // 32-bit size_t's.
1171   double used_after_gc_d = (double) used_after_gc;
1172   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1173   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1174 
1175   // Let's make sure that they are both under the max heap size, which
1176   // by default will make them fit into a size_t.
1177   double desired_capacity_upper_bound = (double) max_heap_size;
1178   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1179                                     desired_capacity_upper_bound);
1180   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1181                                     desired_capacity_upper_bound);
1182 
1183   // We can now safely turn them into size_t's.
1184   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1185   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1186 
1187   // This assert only makes sense here, before we adjust them
1188   // with respect to the min and max heap size.
1189   assert(minimum_desired_capacity <= maximum_desired_capacity,
1190          "minimum_desired_capacity = " SIZE_FORMAT ", "
1191          "maximum_desired_capacity = " SIZE_FORMAT,
1192          minimum_desired_capacity, maximum_desired_capacity);
1193 
1194   // Should not be greater than the heap max size. No need to adjust
1195   // it with respect to the heap min size as it's a lower bound (i.e.,
1196   // we'll try to make the capacity larger than it, not smaller).
1197   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1198   // Should not be less than the heap min size. No need to adjust it
1199   // with respect to the heap max size as it's an upper bound (i.e.,
1200   // we'll try to make the capacity smaller than it, not greater).
1201   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1202 
1203   if (capacity_after_gc < minimum_desired_capacity) {
1204     // Don't expand unless it's significant
1205     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1206 
1207     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1208                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1209                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1210                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1211 
1212     expand(expand_bytes, _workers);
1213 
1214     // No expansion, now see if we want to shrink
1215   } else if (capacity_after_gc > maximum_desired_capacity) {
1216     // Capacity too large, compute shrinking size
1217     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1218 
1219     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1220                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1221                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1222                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1223 
1224     shrink(shrink_bytes);
1225   }
1226 }
1227 
1228 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1229                                                             bool do_gc,
1230                                                             bool clear_all_soft_refs,
1231                                                             bool expect_null_mutator_alloc_region,
1232                                                             bool* gc_succeeded) {
1233   *gc_succeeded = true;
1234   // Let's attempt the allocation first.
1235   HeapWord* result =
1236     attempt_allocation_at_safepoint(word_size,
1237                                     expect_null_mutator_alloc_region);
1238   if (result != NULL) {
1239     return result;
1240   }
1241 
1242   // In a G1 heap, we're supposed to keep allocation from failing by
1243   // incremental pauses.  Therefore, at least for now, we'll favor
1244   // expansion over collection.  (This might change in the future if we can
1245   // do something smarter than full collection to satisfy a failed alloc.)
1246   result = expand_and_allocate(word_size);
1247   if (result != NULL) {
1248     return result;
1249   }
1250 
1251   if (do_gc) {
1252     // Expansion didn't work, we'll try to do a Full GC.
1253     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1254                                        clear_all_soft_refs);
1255   }
1256 
1257   return NULL;
1258 }
1259 
1260 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1261                                                      bool* succeeded) {
1262   assert_at_safepoint_on_vm_thread();
1263 
1264   // Attempts to allocate followed by Full GC.
1265   HeapWord* result =
1266     satisfy_failed_allocation_helper(word_size,
1267                                      true,  /* do_gc */
1268                                      false, /* clear_all_soft_refs */
1269                                      false, /* expect_null_mutator_alloc_region */
1270                                      succeeded);
1271 
1272   if (result != NULL || !*succeeded) {
1273     return result;
1274   }
1275 
1276   // Attempts to allocate followed by Full GC that will collect all soft references.
1277   result = satisfy_failed_allocation_helper(word_size,
1278                                             true, /* do_gc */
1279                                             true, /* clear_all_soft_refs */
1280                                             true, /* expect_null_mutator_alloc_region */
1281                                             succeeded);
1282 
1283   if (result != NULL || !*succeeded) {
1284     return result;
1285   }
1286 
1287   // Attempts to allocate, no GC
1288   result = satisfy_failed_allocation_helper(word_size,
1289                                             false, /* do_gc */
1290                                             false, /* clear_all_soft_refs */
1291                                             true,  /* expect_null_mutator_alloc_region */
1292                                             succeeded);
1293 
1294   if (result != NULL) {
1295     return result;
1296   }
1297 
1298   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1299          "Flag should have been handled and cleared prior to this point");
1300 
1301   // What else?  We might try synchronous finalization later.  If the total
1302   // space available is large enough for the allocation, then a more
1303   // complete compaction phase than we've tried so far might be
1304   // appropriate.
1305   return NULL;
1306 }
1307 
1308 // Attempting to expand the heap sufficiently
1309 // to support an allocation of the given "word_size".  If
1310 // successful, perform the allocation and return the address of the
1311 // allocated block, or else "NULL".
1312 
1313 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1314   assert_at_safepoint_on_vm_thread();
1315 
1316   _verifier->verify_region_sets_optional();
1317 
1318   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1319   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1320                             word_size * HeapWordSize);
1321 
1322 
1323   if (expand(expand_bytes, _workers)) {
1324     _hrm.verify_optional();
1325     _verifier->verify_region_sets_optional();
1326     return attempt_allocation_at_safepoint(word_size,
1327                                            false /* expect_null_mutator_alloc_region */);
1328   }
1329   return NULL;
1330 }
1331 
1332 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1333   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1334   aligned_expand_bytes = align_up(aligned_expand_bytes,
1335                                        HeapRegion::GrainBytes);
1336 
1337   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1338                             expand_bytes, aligned_expand_bytes);
1339 
1340   if (is_maximal_no_gc()) {
1341     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1342     return false;
1343   }
1344 
1345   double expand_heap_start_time_sec = os::elapsedTime();
1346   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1347   assert(regions_to_expand > 0, "Must expand by at least one region");
1348 
1349   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1350   if (expand_time_ms != NULL) {
1351     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1352   }
1353 
1354   if (expanded_by > 0) {
1355     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1356     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1357     g1_policy()->record_new_heap_size(num_regions());
1358   } else {
1359     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1360 
1361     // The expansion of the virtual storage space was unsuccessful.
1362     // Let's see if it was because we ran out of swap.
1363     if (G1ExitOnExpansionFailure &&
1364         _hrm.available() >= regions_to_expand) {
1365       // We had head room...
1366       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1367     }
1368   }
1369   return regions_to_expand > 0;
1370 }
1371 
1372 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1373   size_t aligned_shrink_bytes =
1374     ReservedSpace::page_align_size_down(shrink_bytes);
1375   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1376                                          HeapRegion::GrainBytes);
1377   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1378 
1379   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1380   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1381 
1382 
1383   log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1384                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1385   if (num_regions_removed > 0) {
1386     g1_policy()->record_new_heap_size(num_regions());
1387   } else {
1388     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1389   }
1390 }
1391 
1392 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1393   _verifier->verify_region_sets_optional();
1394 
1395   // We should only reach here at the end of a Full GC which means we
1396   // should not not be holding to any GC alloc regions. The method
1397   // below will make sure of that and do any remaining clean up.
1398   _allocator->abandon_gc_alloc_regions();
1399 
1400   // Instead of tearing down / rebuilding the free lists here, we
1401   // could instead use the remove_all_pending() method on free_list to
1402   // remove only the ones that we need to remove.
1403   tear_down_region_sets(true /* free_list_only */);
1404   shrink_helper(shrink_bytes);
1405   rebuild_region_sets(true /* free_list_only */);
1406 
1407   _hrm.verify_optional();
1408   _verifier->verify_region_sets_optional();
1409 }
1410 
1411 class OldRegionSetChecker : public HeapRegionSetChecker {
1412 public:
1413   void check_mt_safety() {
1414     // Master Old Set MT safety protocol:
1415     // (a) If we're at a safepoint, operations on the master old set
1416     // should be invoked:
1417     // - by the VM thread (which will serialize them), or
1418     // - by the GC workers while holding the FreeList_lock, if we're
1419     //   at a safepoint for an evacuation pause (this lock is taken
1420     //   anyway when an GC alloc region is retired so that a new one
1421     //   is allocated from the free list), or
1422     // - by the GC workers while holding the OldSets_lock, if we're at a
1423     //   safepoint for a cleanup pause.
1424     // (b) If we're not at a safepoint, operations on the master old set
1425     // should be invoked while holding the Heap_lock.
1426 
1427     if (SafepointSynchronize::is_at_safepoint()) {
1428       guarantee(Thread::current()->is_VM_thread() ||
1429                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1430                 "master old set MT safety protocol at a safepoint");
1431     } else {
1432       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1433     }
1434   }
1435   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1436   const char* get_description() { return "Old Regions"; }
1437 };
1438 
1439 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1440 public:
1441   void check_mt_safety() {
1442     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1443               "May only change archive regions during initialization or safepoint.");
1444   }
1445   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1446   const char* get_description() { return "Archive Regions"; }
1447 };
1448 
1449 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1450 public:
1451   void check_mt_safety() {
1452     // Humongous Set MT safety protocol:
1453     // (a) If we're at a safepoint, operations on the master humongous
1454     // set should be invoked by either the VM thread (which will
1455     // serialize them) or by the GC workers while holding the
1456     // OldSets_lock.
1457     // (b) If we're not at a safepoint, operations on the master
1458     // humongous set should be invoked while holding the Heap_lock.
1459 
1460     if (SafepointSynchronize::is_at_safepoint()) {
1461       guarantee(Thread::current()->is_VM_thread() ||
1462                 OldSets_lock->owned_by_self(),
1463                 "master humongous set MT safety protocol at a safepoint");
1464     } else {
1465       guarantee(Heap_lock->owned_by_self(),
1466                 "master humongous set MT safety protocol outside a safepoint");
1467     }
1468   }
1469   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1470   const char* get_description() { return "Humongous Regions"; }
1471 };
1472 
1473 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1474   CollectedHeap(),
1475   _young_gen_sampling_thread(NULL),
1476   _workers(NULL),
1477   _collector_policy(collector_policy),
1478   _card_table(NULL),
1479   _soft_ref_policy(),
1480   _old_set("Old Region Set", new OldRegionSetChecker()),
1481   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1482   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1483   _bot(NULL),
1484   _listener(),
1485   _hrm(),
1486   _allocator(NULL),
1487   _verifier(NULL),
1488   _summary_bytes_used(0),
1489   _archive_allocator(NULL),
1490   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1491   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1492   _expand_heap_after_alloc_failure(true),
1493   _g1mm(NULL),
1494   _humongous_reclaim_candidates(),
1495   _has_humongous_reclaim_candidates(false),
1496   _hr_printer(),
1497   _collector_state(),
1498   _old_marking_cycles_started(0),
1499   _old_marking_cycles_completed(0),
1500   _eden(),
1501   _survivor(),
1502   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1503   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1504   _g1_policy(new G1Policy(_gc_timer_stw)),
1505   _heap_sizing_policy(NULL),
1506   _collection_set(this, _g1_policy),
1507   _hot_card_cache(NULL),
1508   _g1_rem_set(NULL),
1509   _dirty_card_queue_set(false),
1510   _cm(NULL),
1511   _cm_thread(NULL),
1512   _cr(NULL),
1513   _task_queues(NULL),
1514   _evacuation_failed(false),
1515   _evacuation_failed_info_array(NULL),
1516   _preserved_marks_set(true /* in_c_heap */),
1517 #ifndef PRODUCT
1518   _evacuation_failure_alot_for_current_gc(false),
1519   _evacuation_failure_alot_gc_number(0),
1520   _evacuation_failure_alot_count(0),
1521 #endif
1522   _ref_processor_stw(NULL),
1523   _is_alive_closure_stw(this),
1524   _is_subject_to_discovery_stw(this),
1525   _ref_processor_cm(NULL),
1526   _is_alive_closure_cm(this),
1527   _is_subject_to_discovery_cm(this),
1528   _in_cset_fast_test() {
1529 
1530   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1531                           true /* are_GC_task_threads */,
1532                           false /* are_ConcurrentGC_threads */);
1533   _workers->initialize_workers();
1534   _verifier = new G1HeapVerifier(this);
1535 
1536   _allocator = new G1Allocator(this);
1537 
1538   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1539 
1540   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1541 
1542   // Override the default _filler_array_max_size so that no humongous filler
1543   // objects are created.
1544   _filler_array_max_size = _humongous_object_threshold_in_words;
1545 
1546   uint n_queues = ParallelGCThreads;
1547   _task_queues = new RefToScanQueueSet(n_queues);
1548 
1549   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1550 
1551   for (uint i = 0; i < n_queues; i++) {
1552     RefToScanQueue* q = new RefToScanQueue();
1553     q->initialize();
1554     _task_queues->register_queue(i, q);
1555     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1556   }
1557 
1558   // Initialize the G1EvacuationFailureALot counters and flags.
1559   NOT_PRODUCT(reset_evacuation_should_fail();)
1560 
1561   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1562 }
1563 
1564 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1565                                                                  size_t size,
1566                                                                  size_t translation_factor) {
1567   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1568   // Allocate a new reserved space, preferring to use large pages.
1569   ReservedSpace rs(size, preferred_page_size);
1570   G1RegionToSpaceMapper* result  =
1571     G1RegionToSpaceMapper::create_mapper(rs,
1572                                          size,
1573                                          rs.alignment(),
1574                                          HeapRegion::GrainBytes,
1575                                          translation_factor,
1576                                          mtGC);
1577 
1578   os::trace_page_sizes_for_requested_size(description,
1579                                           size,
1580                                           preferred_page_size,
1581                                           rs.alignment(),
1582                                           rs.base(),
1583                                           rs.size());
1584 
1585   return result;
1586 }
1587 
1588 jint G1CollectedHeap::initialize_concurrent_refinement() {
1589   jint ecode = JNI_OK;
1590   _cr = G1ConcurrentRefine::create(&ecode);
1591   return ecode;
1592 }
1593 
1594 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1595   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1596   if (_young_gen_sampling_thread->osthread() == NULL) {
1597     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1598     return JNI_ENOMEM;
1599   }
1600   return JNI_OK;
1601 }
1602 
1603 jint G1CollectedHeap::initialize() {
1604   os::enable_vtime();
1605 
1606   // Necessary to satisfy locking discipline assertions.
1607 
1608   MutexLocker x(Heap_lock);
1609 
1610   // While there are no constraints in the GC code that HeapWordSize
1611   // be any particular value, there are multiple other areas in the
1612   // system which believe this to be true (e.g. oop->object_size in some
1613   // cases incorrectly returns the size in wordSize units rather than
1614   // HeapWordSize).
1615   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1616 
1617   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1618   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1619   size_t heap_alignment = collector_policy()->heap_alignment();
1620 
1621   // Ensure that the sizes are properly aligned.
1622   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1623   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1624   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1625 
1626   // Reserve the maximum.
1627 
1628   // When compressed oops are enabled, the preferred heap base
1629   // is calculated by subtracting the requested size from the
1630   // 32Gb boundary and using the result as the base address for
1631   // heap reservation. If the requested size is not aligned to
1632   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1633   // into the ReservedHeapSpace constructor) then the actual
1634   // base of the reserved heap may end up differing from the
1635   // address that was requested (i.e. the preferred heap base).
1636   // If this happens then we could end up using a non-optimal
1637   // compressed oops mode.
1638 
1639   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1640                                                  heap_alignment);
1641 
1642   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1643 
1644   // Create the barrier set for the entire reserved region.
1645   G1CardTable* ct = new G1CardTable(reserved_region());
1646   ct->initialize();
1647   G1BarrierSet* bs = new G1BarrierSet(ct);
1648   bs->initialize();
1649   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1650   BarrierSet::set_barrier_set(bs);
1651   _card_table = ct;
1652 
1653   // Create the hot card cache.
1654   _hot_card_cache = new G1HotCardCache(this);
1655 
1656   // Carve out the G1 part of the heap.
1657   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1658   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1659   G1RegionToSpaceMapper* heap_storage =
1660     G1RegionToSpaceMapper::create_mapper(g1_rs,
1661                                          g1_rs.size(),
1662                                          page_size,
1663                                          HeapRegion::GrainBytes,
1664                                          1,
1665                                          mtJavaHeap);
1666   os::trace_page_sizes("Heap",
1667                        collector_policy()->min_heap_byte_size(),
1668                        max_byte_size,
1669                        page_size,
1670                        heap_rs.base(),
1671                        heap_rs.size());
1672   heap_storage->set_mapping_changed_listener(&_listener);
1673 
1674   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1675   G1RegionToSpaceMapper* bot_storage =
1676     create_aux_memory_mapper("Block Offset Table",
1677                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1678                              G1BlockOffsetTable::heap_map_factor());
1679 
1680   G1RegionToSpaceMapper* cardtable_storage =
1681     create_aux_memory_mapper("Card Table",
1682                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1683                              G1CardTable::heap_map_factor());
1684 
1685   G1RegionToSpaceMapper* card_counts_storage =
1686     create_aux_memory_mapper("Card Counts Table",
1687                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1688                              G1CardCounts::heap_map_factor());
1689 
1690   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1691   G1RegionToSpaceMapper* prev_bitmap_storage =
1692     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1693   G1RegionToSpaceMapper* next_bitmap_storage =
1694     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1695 
1696   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1697   _card_table->initialize(cardtable_storage);
1698   // Do later initialization work for concurrent refinement.
1699   _hot_card_cache->initialize(card_counts_storage);
1700 
1701   // 6843694 - ensure that the maximum region index can fit
1702   // in the remembered set structures.
1703   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1704   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1705 
1706   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1707   // start within the first card.
1708   guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1709   // Also create a G1 rem set.
1710   _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1711   _g1_rem_set->initialize(max_capacity(), max_regions());
1712 
1713   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1714   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1715   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1716             "too many cards per region");
1717 
1718   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1719 
1720   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1721 
1722   {
1723     HeapWord* start = _hrm.reserved().start();
1724     HeapWord* end = _hrm.reserved().end();
1725     size_t granularity = HeapRegion::GrainBytes;
1726 
1727     _in_cset_fast_test.initialize(start, end, granularity);
1728     _humongous_reclaim_candidates.initialize(start, end, granularity);
1729   }
1730 
1731   // Create the G1ConcurrentMark data structure and thread.
1732   // (Must do this late, so that "max_regions" is defined.)
1733   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1734   if (_cm == NULL || !_cm->completed_initialization()) {
1735     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1736     return JNI_ENOMEM;
1737   }
1738   _cm_thread = _cm->cm_thread();
1739 
1740   // Now expand into the initial heap size.
1741   if (!expand(init_byte_size, _workers)) {
1742     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1743     return JNI_ENOMEM;
1744   }
1745 
1746   // Perform any initialization actions delegated to the policy.
1747   g1_policy()->init(this, &_collection_set);
1748 
1749   G1BarrierSet::satb_mark_queue_set().initialize(this,
1750                                                  SATB_Q_CBL_mon,
1751                                                  SATB_Q_FL_lock,
1752                                                  G1SATBProcessCompletedThreshold,
1753                                                  G1SATBBufferEnqueueingThresholdPercent,
1754                                                  Shared_SATB_Q_lock);
1755 
1756   jint ecode = initialize_concurrent_refinement();
1757   if (ecode != JNI_OK) {
1758     return ecode;
1759   }
1760 
1761   ecode = initialize_young_gen_sampling_thread();
1762   if (ecode != JNI_OK) {
1763     return ecode;
1764   }
1765 
1766   G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1767                                                   DirtyCardQ_FL_lock,
1768                                                   (int)concurrent_refine()->yellow_zone(),
1769                                                   (int)concurrent_refine()->red_zone(),
1770                                                   Shared_DirtyCardQ_lock,
1771                                                   NULL,  // fl_owner
1772                                                   true); // init_free_ids
1773 
1774   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1775                                     DirtyCardQ_FL_lock,
1776                                     -1, // never trigger processing
1777                                     -1, // no limit on length
1778                                     Shared_DirtyCardQ_lock,
1779                                     &G1BarrierSet::dirty_card_queue_set());
1780 
1781   // Here we allocate the dummy HeapRegion that is required by the
1782   // G1AllocRegion class.
1783   HeapRegion* dummy_region = _hrm.get_dummy_region();
1784 
1785   // We'll re-use the same region whether the alloc region will
1786   // require BOT updates or not and, if it doesn't, then a non-young
1787   // region will complain that it cannot support allocations without
1788   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1789   dummy_region->set_eden();
1790   // Make sure it's full.
1791   dummy_region->set_top(dummy_region->end());
1792   G1AllocRegion::setup(this, dummy_region);
1793 
1794   _allocator->init_mutator_alloc_region();
1795 
1796   // Do create of the monitoring and management support so that
1797   // values in the heap have been properly initialized.
1798   _g1mm = new G1MonitoringSupport(this);
1799 
1800   G1StringDedup::initialize();
1801 
1802   _preserved_marks_set.init(ParallelGCThreads);
1803 
1804   _collection_set.initialize(max_regions());
1805 
1806   return JNI_OK;
1807 }
1808 
1809 void G1CollectedHeap::stop() {
1810   // Stop all concurrent threads. We do this to make sure these threads
1811   // do not continue to execute and access resources (e.g. logging)
1812   // that are destroyed during shutdown.
1813   _cr->stop();
1814   _young_gen_sampling_thread->stop();
1815   _cm_thread->stop();
1816   if (G1StringDedup::is_enabled()) {
1817     G1StringDedup::stop();
1818   }
1819 }
1820 
1821 void G1CollectedHeap::safepoint_synchronize_begin() {
1822   SuspendibleThreadSet::synchronize();
1823 }
1824 
1825 void G1CollectedHeap::safepoint_synchronize_end() {
1826   SuspendibleThreadSet::desynchronize();
1827 }
1828 
1829 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1830   return HeapRegion::max_region_size();
1831 }
1832 
1833 void G1CollectedHeap::post_initialize() {
1834   CollectedHeap::post_initialize();
1835   ref_processing_init();
1836 }
1837 
1838 void G1CollectedHeap::ref_processing_init() {
1839   // Reference processing in G1 currently works as follows:
1840   //
1841   // * There are two reference processor instances. One is
1842   //   used to record and process discovered references
1843   //   during concurrent marking; the other is used to
1844   //   record and process references during STW pauses
1845   //   (both full and incremental).
1846   // * Both ref processors need to 'span' the entire heap as
1847   //   the regions in the collection set may be dotted around.
1848   //
1849   // * For the concurrent marking ref processor:
1850   //   * Reference discovery is enabled at initial marking.
1851   //   * Reference discovery is disabled and the discovered
1852   //     references processed etc during remarking.
1853   //   * Reference discovery is MT (see below).
1854   //   * Reference discovery requires a barrier (see below).
1855   //   * Reference processing may or may not be MT
1856   //     (depending on the value of ParallelRefProcEnabled
1857   //     and ParallelGCThreads).
1858   //   * A full GC disables reference discovery by the CM
1859   //     ref processor and abandons any entries on it's
1860   //     discovered lists.
1861   //
1862   // * For the STW processor:
1863   //   * Non MT discovery is enabled at the start of a full GC.
1864   //   * Processing and enqueueing during a full GC is non-MT.
1865   //   * During a full GC, references are processed after marking.
1866   //
1867   //   * Discovery (may or may not be MT) is enabled at the start
1868   //     of an incremental evacuation pause.
1869   //   * References are processed near the end of a STW evacuation pause.
1870   //   * For both types of GC:
1871   //     * Discovery is atomic - i.e. not concurrent.
1872   //     * Reference discovery will not need a barrier.
1873 
1874   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1875 
1876   // Concurrent Mark ref processor
1877   _ref_processor_cm =
1878     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1879                            mt_processing,                                  // mt processing
1880                            ParallelGCThreads,                              // degree of mt processing
1881                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1882                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1883                            false,                                          // Reference discovery is not atomic
1884                            &_is_alive_closure_cm,                          // is alive closure
1885                            true);                                          // allow changes to number of processing threads
1886 
1887   // STW ref processor
1888   _ref_processor_stw =
1889     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1890                            mt_processing,                        // mt processing
1891                            ParallelGCThreads,                    // degree of mt processing
1892                            (ParallelGCThreads > 1),              // mt discovery
1893                            ParallelGCThreads,                    // degree of mt discovery
1894                            true,                                 // Reference discovery is atomic
1895                            &_is_alive_closure_stw,               // is alive closure
1896                            true);                                // allow changes to number of processing threads
1897 }
1898 
1899 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1900   return _collector_policy;
1901 }
1902 
1903 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1904   return &_soft_ref_policy;
1905 }
1906 
1907 size_t G1CollectedHeap::capacity() const {
1908   return _hrm.length() * HeapRegion::GrainBytes;
1909 }
1910 
1911 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1912   return _hrm.total_free_bytes();
1913 }
1914 
1915 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1916   _hot_card_cache->drain(cl, worker_i);
1917 }
1918 
1919 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1920   DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1921   size_t n_completed_buffers = 0;
1922   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1923     n_completed_buffers++;
1924   }
1925   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1926   dcqs.clear_n_completed_buffers();
1927   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1928 }
1929 
1930 // Computes the sum of the storage used by the various regions.
1931 size_t G1CollectedHeap::used() const {
1932   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1933   if (_archive_allocator != NULL) {
1934     result += _archive_allocator->used();
1935   }
1936   return result;
1937 }
1938 
1939 size_t G1CollectedHeap::used_unlocked() const {
1940   return _summary_bytes_used;
1941 }
1942 
1943 class SumUsedClosure: public HeapRegionClosure {
1944   size_t _used;
1945 public:
1946   SumUsedClosure() : _used(0) {}
1947   bool do_heap_region(HeapRegion* r) {
1948     _used += r->used();
1949     return false;
1950   }
1951   size_t result() { return _used; }
1952 };
1953 
1954 size_t G1CollectedHeap::recalculate_used() const {
1955   SumUsedClosure blk;
1956   heap_region_iterate(&blk);
1957   return blk.result();
1958 }
1959 
1960 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1961   switch (cause) {
1962     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1963     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1964     case GCCause::_wb_conc_mark:                        return true;
1965     default :                                           return false;
1966   }
1967 }
1968 
1969 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1970   switch (cause) {
1971     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
1972     case GCCause::_g1_humongous_allocation: return true;
1973     default:                                return is_user_requested_concurrent_full_gc(cause);
1974   }
1975 }
1976 
1977 #ifndef PRODUCT
1978 void G1CollectedHeap::allocate_dummy_regions() {
1979   // Let's fill up most of the region
1980   size_t word_size = HeapRegion::GrainWords - 1024;
1981   // And as a result the region we'll allocate will be humongous.
1982   guarantee(is_humongous(word_size), "sanity");
1983 
1984   // _filler_array_max_size is set to humongous object threshold
1985   // but temporarily change it to use CollectedHeap::fill_with_object().
1986   SizeTFlagSetting fs(_filler_array_max_size, word_size);
1987 
1988   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1989     // Let's use the existing mechanism for the allocation
1990     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1991     if (dummy_obj != NULL) {
1992       MemRegion mr(dummy_obj, word_size);
1993       CollectedHeap::fill_with_object(mr);
1994     } else {
1995       // If we can't allocate once, we probably cannot allocate
1996       // again. Let's get out of the loop.
1997       break;
1998     }
1999   }
2000 }
2001 #endif // !PRODUCT
2002 
2003 void G1CollectedHeap::increment_old_marking_cycles_started() {
2004   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2005          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2006          "Wrong marking cycle count (started: %d, completed: %d)",
2007          _old_marking_cycles_started, _old_marking_cycles_completed);
2008 
2009   _old_marking_cycles_started++;
2010 }
2011 
2012 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2013   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2014 
2015   // We assume that if concurrent == true, then the caller is a
2016   // concurrent thread that was joined the Suspendible Thread
2017   // Set. If there's ever a cheap way to check this, we should add an
2018   // assert here.
2019 
2020   // Given that this method is called at the end of a Full GC or of a
2021   // concurrent cycle, and those can be nested (i.e., a Full GC can
2022   // interrupt a concurrent cycle), the number of full collections
2023   // completed should be either one (in the case where there was no
2024   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2025   // behind the number of full collections started.
2026 
2027   // This is the case for the inner caller, i.e. a Full GC.
2028   assert(concurrent ||
2029          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2030          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2031          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2032          "is inconsistent with _old_marking_cycles_completed = %u",
2033          _old_marking_cycles_started, _old_marking_cycles_completed);
2034 
2035   // This is the case for the outer caller, i.e. the concurrent cycle.
2036   assert(!concurrent ||
2037          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2038          "for outer caller (concurrent cycle): "
2039          "_old_marking_cycles_started = %u "
2040          "is inconsistent with _old_marking_cycles_completed = %u",
2041          _old_marking_cycles_started, _old_marking_cycles_completed);
2042 
2043   _old_marking_cycles_completed += 1;
2044 
2045   // We need to clear the "in_progress" flag in the CM thread before
2046   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2047   // is set) so that if a waiter requests another System.gc() it doesn't
2048   // incorrectly see that a marking cycle is still in progress.
2049   if (concurrent) {
2050     _cm_thread->set_idle();
2051   }
2052 
2053   // This notify_all() will ensure that a thread that called
2054   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2055   // and it's waiting for a full GC to finish will be woken up. It is
2056   // waiting in VM_G1CollectForAllocation::doit_epilogue().
2057   FullGCCount_lock->notify_all();
2058 }
2059 
2060 void G1CollectedHeap::collect(GCCause::Cause cause) {
2061   assert_heap_not_locked();
2062 
2063   uint gc_count_before;
2064   uint old_marking_count_before;
2065   uint full_gc_count_before;
2066   bool retry_gc;
2067 
2068   do {
2069     retry_gc = false;
2070 
2071     {
2072       MutexLocker ml(Heap_lock);
2073 
2074       // Read the GC count while holding the Heap_lock
2075       gc_count_before = total_collections();
2076       full_gc_count_before = total_full_collections();
2077       old_marking_count_before = _old_marking_cycles_started;
2078     }
2079 
2080     if (should_do_concurrent_full_gc(cause)) {
2081       // Schedule an initial-mark evacuation pause that will start a
2082       // concurrent cycle. We're setting word_size to 0 which means that
2083       // we are not requesting a post-GC allocation.
2084       VM_G1CollectForAllocation op(0,     /* word_size */
2085                                    gc_count_before,
2086                                    cause,
2087                                    true,  /* should_initiate_conc_mark */
2088                                    g1_policy()->max_pause_time_ms());
2089       VMThread::execute(&op);
2090       if (!op.pause_succeeded()) {
2091         if (old_marking_count_before == _old_marking_cycles_started) {
2092           retry_gc = op.should_retry_gc();
2093         } else {
2094           // A Full GC happened while we were trying to schedule the
2095           // initial-mark GC. No point in starting a new cycle given
2096           // that the whole heap was collected anyway.
2097         }
2098 
2099         if (retry_gc) {
2100           if (GCLocker::is_active_and_needs_gc()) {
2101             GCLocker::stall_until_clear();
2102           }
2103         }
2104       }
2105     } else {
2106       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2107           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2108 
2109         // Schedule a standard evacuation pause. We're setting word_size
2110         // to 0 which means that we are not requesting a post-GC allocation.
2111         VM_G1CollectForAllocation op(0,     /* word_size */
2112                                      gc_count_before,
2113                                      cause,
2114                                      false, /* should_initiate_conc_mark */
2115                                      g1_policy()->max_pause_time_ms());
2116         VMThread::execute(&op);
2117       } else {
2118         // Schedule a Full GC.
2119         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2120         VMThread::execute(&op);
2121       }
2122     }
2123   } while (retry_gc);
2124 }
2125 
2126 bool G1CollectedHeap::is_in(const void* p) const {
2127   if (_hrm.reserved().contains(p)) {
2128     // Given that we know that p is in the reserved space,
2129     // heap_region_containing() should successfully
2130     // return the containing region.
2131     HeapRegion* hr = heap_region_containing(p);
2132     return hr->is_in(p);
2133   } else {
2134     return false;
2135   }
2136 }
2137 
2138 #ifdef ASSERT
2139 bool G1CollectedHeap::is_in_exact(const void* p) const {
2140   bool contains = reserved_region().contains(p);
2141   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2142   if (contains && available) {
2143     return true;
2144   } else {
2145     return false;
2146   }
2147 }
2148 #endif
2149 
2150 // Iteration functions.
2151 
2152 // Iterates an ObjectClosure over all objects within a HeapRegion.
2153 
2154 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2155   ObjectClosure* _cl;
2156 public:
2157   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2158   bool do_heap_region(HeapRegion* r) {
2159     if (!r->is_continues_humongous()) {
2160       r->object_iterate(_cl);
2161     }
2162     return false;
2163   }
2164 };
2165 
2166 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2167   IterateObjectClosureRegionClosure blk(cl);
2168   heap_region_iterate(&blk);
2169 }
2170 
2171 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2172   _hrm.iterate(cl);
2173 }
2174 
2175 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2176                                                                  HeapRegionClaimer *hrclaimer,
2177                                                                  uint worker_id) const {
2178   _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2179 }
2180 
2181 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2182                                                          HeapRegionClaimer *hrclaimer) const {
2183   _hrm.par_iterate(cl, hrclaimer, 0);
2184 }
2185 
2186 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2187   _collection_set.iterate(cl);
2188 }
2189 
2190 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2191   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2192 }
2193 
2194 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2195   HeapRegion* hr = heap_region_containing(addr);
2196   return hr->block_start(addr);
2197 }
2198 
2199 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2200   HeapRegion* hr = heap_region_containing(addr);
2201   return hr->block_size(addr);
2202 }
2203 
2204 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2205   HeapRegion* hr = heap_region_containing(addr);
2206   return hr->block_is_obj(addr);
2207 }
2208 
2209 bool G1CollectedHeap::supports_tlab_allocation() const {
2210   return true;
2211 }
2212 
2213 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2214   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2215 }
2216 
2217 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2218   return _eden.length() * HeapRegion::GrainBytes;
2219 }
2220 
2221 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2222 // must be equal to the humongous object limit.
2223 size_t G1CollectedHeap::max_tlab_size() const {
2224   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2225 }
2226 
2227 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2228   return _allocator->unsafe_max_tlab_alloc();
2229 }
2230 
2231 size_t G1CollectedHeap::max_capacity() const {
2232   return _hrm.reserved().byte_size();
2233 }
2234 
2235 jlong G1CollectedHeap::millis_since_last_gc() {
2236   // See the notes in GenCollectedHeap::millis_since_last_gc()
2237   // for more information about the implementation.
2238   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2239     _g1_policy->collection_pause_end_millis();
2240   if (ret_val < 0) {
2241     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2242       ". returning zero instead.", ret_val);
2243     return 0;
2244   }
2245   return ret_val;
2246 }
2247 
2248 void G1CollectedHeap::deduplicate_string(oop str) {
2249   assert(java_lang_String::is_instance(str), "invariant");
2250 
2251   if (G1StringDedup::is_enabled()) {
2252     G1StringDedup::deduplicate(str);
2253   }
2254 }
2255 
2256 void G1CollectedHeap::prepare_for_verify() {
2257   _verifier->prepare_for_verify();
2258 }
2259 
2260 void G1CollectedHeap::verify(VerifyOption vo) {
2261   _verifier->verify(vo);
2262 }
2263 
2264 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2265   return true;
2266 }
2267 
2268 const char* const* G1CollectedHeap::concurrent_phases() const {
2269   return _cm_thread->concurrent_phases();
2270 }
2271 
2272 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2273   return _cm_thread->request_concurrent_phase(phase);
2274 }
2275 
2276 class PrintRegionClosure: public HeapRegionClosure {
2277   outputStream* _st;
2278 public:
2279   PrintRegionClosure(outputStream* st) : _st(st) {}
2280   bool do_heap_region(HeapRegion* r) {
2281     r->print_on(_st);
2282     return false;
2283   }
2284 };
2285 
2286 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2287                                        const HeapRegion* hr,
2288                                        const VerifyOption vo) const {
2289   switch (vo) {
2290   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2291   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2292   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2293   default:                            ShouldNotReachHere();
2294   }
2295   return false; // keep some compilers happy
2296 }
2297 
2298 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2299                                        const VerifyOption vo) const {
2300   switch (vo) {
2301   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2302   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2303   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2304   default:                            ShouldNotReachHere();
2305   }
2306   return false; // keep some compilers happy
2307 }
2308 
2309 void G1CollectedHeap::print_heap_regions() const {
2310   LogTarget(Trace, gc, heap, region) lt;
2311   if (lt.is_enabled()) {
2312     LogStream ls(lt);
2313     print_regions_on(&ls);
2314   }
2315 }
2316 
2317 void G1CollectedHeap::print_on(outputStream* st) const {
2318   st->print(" %-20s", "garbage-first heap");
2319   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2320             capacity()/K, used_unlocked()/K);
2321   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2322             p2i(_hrm.reserved().start()),
2323             p2i(_hrm.reserved().end()));
2324   st->cr();
2325   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2326   uint young_regions = young_regions_count();
2327   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2328             (size_t) young_regions * HeapRegion::GrainBytes / K);
2329   uint survivor_regions = survivor_regions_count();
2330   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2331             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2332   st->cr();
2333   MetaspaceUtils::print_on(st);
2334 }
2335 
2336 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2337   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2338                "HS=humongous(starts), HC=humongous(continues), "
2339                "CS=collection set, F=free, A=archive, "
2340                "TAMS=top-at-mark-start (previous, next)");
2341   PrintRegionClosure blk(st);
2342   heap_region_iterate(&blk);
2343 }
2344 
2345 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2346   print_on(st);
2347 
2348   // Print the per-region information.
2349   print_regions_on(st);
2350 }
2351 
2352 void G1CollectedHeap::print_on_error(outputStream* st) const {
2353   this->CollectedHeap::print_on_error(st);
2354 
2355   if (_cm != NULL) {
2356     st->cr();
2357     _cm->print_on_error(st);
2358   }
2359 }
2360 
2361 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2362   workers()->print_worker_threads_on(st);
2363   _cm_thread->print_on(st);
2364   st->cr();
2365   _cm->print_worker_threads_on(st);
2366   _cr->print_threads_on(st);
2367   _young_gen_sampling_thread->print_on(st);
2368   if (G1StringDedup::is_enabled()) {
2369     G1StringDedup::print_worker_threads_on(st);
2370   }
2371 }
2372 
2373 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2374   workers()->threads_do(tc);
2375   tc->do_thread(_cm_thread);
2376   _cm->threads_do(tc);
2377   _cr->threads_do(tc);
2378   tc->do_thread(_young_gen_sampling_thread);
2379   if (G1StringDedup::is_enabled()) {
2380     G1StringDedup::threads_do(tc);
2381   }
2382 }
2383 
2384 void G1CollectedHeap::print_tracing_info() const {
2385   g1_rem_set()->print_summary_info();
2386   concurrent_mark()->print_summary_info();
2387 }
2388 
2389 #ifndef PRODUCT
2390 // Helpful for debugging RSet issues.
2391 
2392 class PrintRSetsClosure : public HeapRegionClosure {
2393 private:
2394   const char* _msg;
2395   size_t _occupied_sum;
2396 
2397 public:
2398   bool do_heap_region(HeapRegion* r) {
2399     HeapRegionRemSet* hrrs = r->rem_set();
2400     size_t occupied = hrrs->occupied();
2401     _occupied_sum += occupied;
2402 
2403     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2404     if (occupied == 0) {
2405       tty->print_cr("  RSet is empty");
2406     } else {
2407       hrrs->print();
2408     }
2409     tty->print_cr("----------");
2410     return false;
2411   }
2412 
2413   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2414     tty->cr();
2415     tty->print_cr("========================================");
2416     tty->print_cr("%s", msg);
2417     tty->cr();
2418   }
2419 
2420   ~PrintRSetsClosure() {
2421     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2422     tty->print_cr("========================================");
2423     tty->cr();
2424   }
2425 };
2426 
2427 void G1CollectedHeap::print_cset_rsets() {
2428   PrintRSetsClosure cl("Printing CSet RSets");
2429   collection_set_iterate(&cl);
2430 }
2431 
2432 void G1CollectedHeap::print_all_rsets() {
2433   PrintRSetsClosure cl("Printing All RSets");;
2434   heap_region_iterate(&cl);
2435 }
2436 #endif // PRODUCT
2437 
2438 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2439 
2440   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2441   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2442   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2443 
2444   size_t eden_capacity_bytes =
2445     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2446 
2447   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2448   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2449                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2450 }
2451 
2452 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2453   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2454                        stats->unused(), stats->used(), stats->region_end_waste(),
2455                        stats->regions_filled(), stats->direct_allocated(),
2456                        stats->failure_used(), stats->failure_waste());
2457 }
2458 
2459 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2460   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2461   gc_tracer->report_gc_heap_summary(when, heap_summary);
2462 
2463   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2464   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2465 }
2466 
2467 G1CollectedHeap* G1CollectedHeap::heap() {
2468   CollectedHeap* heap = Universe::heap();
2469   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2470   assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2471   return (G1CollectedHeap*)heap;
2472 }
2473 
2474 void G1CollectedHeap::gc_prologue(bool full) {
2475   // always_do_update_barrier = false;
2476   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2477 
2478   // This summary needs to be printed before incrementing total collections.
2479   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2480 
2481   // Update common counters.
2482   increment_total_collections(full /* full gc */);
2483   if (full) {
2484     increment_old_marking_cycles_started();
2485   }
2486 
2487   // Fill TLAB's and such
2488   double start = os::elapsedTime();
2489   ensure_parsability(true);
2490   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2491 }
2492 
2493 void G1CollectedHeap::gc_epilogue(bool full) {
2494   // Update common counters.
2495   if (full) {
2496     // Update the number of full collections that have been completed.
2497     increment_old_marking_cycles_completed(false /* concurrent */);
2498   }
2499 
2500   // We are at the end of the GC. Total collections has already been increased.
2501   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2502 
2503   // FIXME: what is this about?
2504   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2505   // is set.
2506 #if COMPILER2_OR_JVMCI
2507   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2508 #endif
2509   // always_do_update_barrier = true;
2510 
2511   double start = os::elapsedTime();
2512   resize_all_tlabs();
2513   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2514 
2515   MemoryService::track_memory_usage();
2516   // We have just completed a GC. Update the soft reference
2517   // policy with the new heap occupancy
2518   Universe::update_heap_info_at_gc();
2519 }
2520 
2521 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2522                                                uint gc_count_before,
2523                                                bool* succeeded,
2524                                                GCCause::Cause gc_cause) {
2525   assert_heap_not_locked_and_not_at_safepoint();
2526   VM_G1CollectForAllocation op(word_size,
2527                                gc_count_before,
2528                                gc_cause,
2529                                false, /* should_initiate_conc_mark */
2530                                g1_policy()->max_pause_time_ms());
2531   VMThread::execute(&op);
2532 
2533   HeapWord* result = op.result();
2534   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2535   assert(result == NULL || ret_succeeded,
2536          "the result should be NULL if the VM did not succeed");
2537   *succeeded = ret_succeeded;
2538 
2539   assert_heap_not_locked();
2540   return result;
2541 }
2542 
2543 void G1CollectedHeap::do_concurrent_mark() {
2544   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2545   if (!_cm_thread->in_progress()) {
2546     _cm_thread->set_started();
2547     CGC_lock->notify();
2548   }
2549 }
2550 
2551 size_t G1CollectedHeap::pending_card_num() {
2552   size_t extra_cards = 0;
2553   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2554     DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2555     extra_cards += dcq.size();
2556   }
2557   DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2558   size_t buffer_size = dcqs.buffer_size();
2559   size_t buffer_num = dcqs.completed_buffers_num();
2560 
2561   return buffer_size * buffer_num + extra_cards;
2562 }
2563 
2564 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2565   // We don't nominate objects with many remembered set entries, on
2566   // the assumption that such objects are likely still live.
2567   HeapRegionRemSet* rem_set = r->rem_set();
2568 
2569   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2570          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2571          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2572 }
2573 
2574 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2575  private:
2576   size_t _total_humongous;
2577   size_t _candidate_humongous;
2578 
2579   DirtyCardQueue _dcq;
2580 
2581   bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2582     assert(region->is_starts_humongous(), "Must start a humongous object");
2583 
2584     oop obj = oop(region->bottom());
2585 
2586     // Dead objects cannot be eager reclaim candidates. Due to class
2587     // unloading it is unsafe to query their classes so we return early.
2588     if (g1h->is_obj_dead(obj, region)) {
2589       return false;
2590     }
2591 
2592     // If we do not have a complete remembered set for the region, then we can
2593     // not be sure that we have all references to it.
2594     if (!region->rem_set()->is_complete()) {
2595       return false;
2596     }
2597     // Candidate selection must satisfy the following constraints
2598     // while concurrent marking is in progress:
2599     //
2600     // * In order to maintain SATB invariants, an object must not be
2601     // reclaimed if it was allocated before the start of marking and
2602     // has not had its references scanned.  Such an object must have
2603     // its references (including type metadata) scanned to ensure no
2604     // live objects are missed by the marking process.  Objects
2605     // allocated after the start of concurrent marking don't need to
2606     // be scanned.
2607     //
2608     // * An object must not be reclaimed if it is on the concurrent
2609     // mark stack.  Objects allocated after the start of concurrent
2610     // marking are never pushed on the mark stack.
2611     //
2612     // Nominating only objects allocated after the start of concurrent
2613     // marking is sufficient to meet both constraints.  This may miss
2614     // some objects that satisfy the constraints, but the marking data
2615     // structures don't support efficiently performing the needed
2616     // additional tests or scrubbing of the mark stack.
2617     //
2618     // However, we presently only nominate is_typeArray() objects.
2619     // A humongous object containing references induces remembered
2620     // set entries on other regions.  In order to reclaim such an
2621     // object, those remembered sets would need to be cleaned up.
2622     //
2623     // We also treat is_typeArray() objects specially, allowing them
2624     // to be reclaimed even if allocated before the start of
2625     // concurrent mark.  For this we rely on mark stack insertion to
2626     // exclude is_typeArray() objects, preventing reclaiming an object
2627     // that is in the mark stack.  We also rely on the metadata for
2628     // such objects to be built-in and so ensured to be kept live.
2629     // Frequent allocation and drop of large binary blobs is an
2630     // important use case for eager reclaim, and this special handling
2631     // may reduce needed headroom.
2632 
2633     return obj->is_typeArray() &&
2634            g1h->is_potential_eager_reclaim_candidate(region);
2635   }
2636 
2637  public:
2638   RegisterHumongousWithInCSetFastTestClosure()
2639   : _total_humongous(0),
2640     _candidate_humongous(0),
2641     _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2642   }
2643 
2644   virtual bool do_heap_region(HeapRegion* r) {
2645     if (!r->is_starts_humongous()) {
2646       return false;
2647     }
2648     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2649 
2650     bool is_candidate = humongous_region_is_candidate(g1h, r);
2651     uint rindex = r->hrm_index();
2652     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2653     if (is_candidate) {
2654       _candidate_humongous++;
2655       g1h->register_humongous_region_with_cset(rindex);
2656       // Is_candidate already filters out humongous object with large remembered sets.
2657       // If we have a humongous object with a few remembered sets, we simply flush these
2658       // remembered set entries into the DCQS. That will result in automatic
2659       // re-evaluation of their remembered set entries during the following evacuation
2660       // phase.
2661       if (!r->rem_set()->is_empty()) {
2662         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2663                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2664         G1CardTable* ct = g1h->card_table();
2665         HeapRegionRemSetIterator hrrs(r->rem_set());
2666         size_t card_index;
2667         while (hrrs.has_next(card_index)) {
2668           jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2669           // The remembered set might contain references to already freed
2670           // regions. Filter out such entries to avoid failing card table
2671           // verification.
2672           if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2673             if (*card_ptr != G1CardTable::dirty_card_val()) {
2674               *card_ptr = G1CardTable::dirty_card_val();
2675               _dcq.enqueue(card_ptr);
2676             }
2677           }
2678         }
2679         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2680                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2681                hrrs.n_yielded(), r->rem_set()->occupied());
2682         // We should only clear the card based remembered set here as we will not
2683         // implicitly rebuild anything else during eager reclaim. Note that at the moment
2684         // (and probably never) we do not enter this path if there are other kind of
2685         // remembered sets for this region.
2686         r->rem_set()->clear_locked(true /* only_cardset */);
2687         // Clear_locked() above sets the state to Empty. However we want to continue
2688         // collecting remembered set entries for humongous regions that were not
2689         // reclaimed.
2690         r->rem_set()->set_state_complete();
2691       }
2692       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2693     }
2694     _total_humongous++;
2695 
2696     return false;
2697   }
2698 
2699   size_t total_humongous() const { return _total_humongous; }
2700   size_t candidate_humongous() const { return _candidate_humongous; }
2701 
2702   void flush_rem_set_entries() { _dcq.flush(); }
2703 };
2704 
2705 void G1CollectedHeap::register_humongous_regions_with_cset() {
2706   if (!G1EagerReclaimHumongousObjects) {
2707     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2708     return;
2709   }
2710   double time = os::elapsed_counter();
2711 
2712   // Collect reclaim candidate information and register candidates with cset.
2713   RegisterHumongousWithInCSetFastTestClosure cl;
2714   heap_region_iterate(&cl);
2715 
2716   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2717   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2718                                                                   cl.total_humongous(),
2719                                                                   cl.candidate_humongous());
2720   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2721 
2722   // Finally flush all remembered set entries to re-check into the global DCQS.
2723   cl.flush_rem_set_entries();
2724 }
2725 
2726 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2727   public:
2728     bool do_heap_region(HeapRegion* hr) {
2729       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2730         hr->verify_rem_set();
2731       }
2732       return false;
2733     }
2734 };
2735 
2736 uint G1CollectedHeap::num_task_queues() const {
2737   return _task_queues->size();
2738 }
2739 
2740 #if TASKQUEUE_STATS
2741 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2742   st->print_raw_cr("GC Task Stats");
2743   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2744   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2745 }
2746 
2747 void G1CollectedHeap::print_taskqueue_stats() const {
2748   if (!log_is_enabled(Trace, gc, task, stats)) {
2749     return;
2750   }
2751   Log(gc, task, stats) log;
2752   ResourceMark rm;
2753   LogStream ls(log.trace());
2754   outputStream* st = &ls;
2755 
2756   print_taskqueue_stats_hdr(st);
2757 
2758   TaskQueueStats totals;
2759   const uint n = num_task_queues();
2760   for (uint i = 0; i < n; ++i) {
2761     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2762     totals += task_queue(i)->stats;
2763   }
2764   st->print_raw("tot "); totals.print(st); st->cr();
2765 
2766   DEBUG_ONLY(totals.verify());
2767 }
2768 
2769 void G1CollectedHeap::reset_taskqueue_stats() {
2770   const uint n = num_task_queues();
2771   for (uint i = 0; i < n; ++i) {
2772     task_queue(i)->stats.reset();
2773   }
2774 }
2775 #endif // TASKQUEUE_STATS
2776 
2777 void G1CollectedHeap::wait_for_root_region_scanning() {
2778   double scan_wait_start = os::elapsedTime();
2779   // We have to wait until the CM threads finish scanning the
2780   // root regions as it's the only way to ensure that all the
2781   // objects on them have been correctly scanned before we start
2782   // moving them during the GC.
2783   bool waited = _cm->root_regions()->wait_until_scan_finished();
2784   double wait_time_ms = 0.0;
2785   if (waited) {
2786     double scan_wait_end = os::elapsedTime();
2787     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2788   }
2789   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2790 }
2791 
2792 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2793 private:
2794   G1HRPrinter* _hr_printer;
2795 public:
2796   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2797 
2798   virtual bool do_heap_region(HeapRegion* r) {
2799     _hr_printer->cset(r);
2800     return false;
2801   }
2802 };
2803 
2804 void G1CollectedHeap::start_new_collection_set() {
2805   collection_set()->start_incremental_building();
2806 
2807   clear_cset_fast_test();
2808 
2809   guarantee(_eden.length() == 0, "eden should have been cleared");
2810   g1_policy()->transfer_survivors_to_cset(survivor());
2811 }
2812 
2813 bool
2814 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2815   assert_at_safepoint_on_vm_thread();
2816   guarantee(!is_gc_active(), "collection is not reentrant");
2817 
2818   if (GCLocker::check_active_before_gc()) {
2819     return false;
2820   }
2821 
2822   _gc_timer_stw->register_gc_start();
2823 
2824   GCIdMark gc_id_mark;
2825   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2826 
2827   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2828   ResourceMark rm;
2829 
2830   g1_policy()->note_gc_start();
2831 
2832   wait_for_root_region_scanning();
2833 
2834   print_heap_before_gc();
2835   print_heap_regions();
2836   trace_heap_before_gc(_gc_tracer_stw);
2837 
2838   _verifier->verify_region_sets_optional();
2839   _verifier->verify_dirty_young_regions();
2840 
2841   // We should not be doing initial mark unless the conc mark thread is running
2842   if (!_cm_thread->should_terminate()) {
2843     // This call will decide whether this pause is an initial-mark
2844     // pause. If it is, in_initial_mark_gc() will return true
2845     // for the duration of this pause.
2846     g1_policy()->decide_on_conc_mark_initiation();
2847   }
2848 
2849   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2850   assert(!collector_state()->in_initial_mark_gc() ||
2851           collector_state()->in_young_only_phase(), "sanity");
2852 
2853   // We also do not allow mixed GCs during marking.
2854   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2855 
2856   // Record whether this pause is an initial mark. When the current
2857   // thread has completed its logging output and it's safe to signal
2858   // the CM thread, the flag's value in the policy has been reset.
2859   bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2860 
2861   // Inner scope for scope based logging, timers, and stats collection
2862   {
2863     EvacuationInfo evacuation_info;
2864 
2865     if (collector_state()->in_initial_mark_gc()) {
2866       // We are about to start a marking cycle, so we increment the
2867       // full collection counter.
2868       increment_old_marking_cycles_started();
2869       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2870     }
2871 
2872     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2873 
2874     GCTraceCPUTime tcpu;
2875 
2876     G1HeapVerifier::G1VerifyType verify_type;
2877     FormatBuffer<> gc_string("Pause Young ");
2878     if (collector_state()->in_initial_mark_gc()) {
2879       gc_string.append("(Concurrent Start)");
2880       verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2881     } else if (collector_state()->in_young_only_phase()) {
2882       if (collector_state()->in_young_gc_before_mixed()) {
2883         gc_string.append("(Prepare Mixed)");
2884       } else {
2885         gc_string.append("(Normal)");
2886       }
2887       verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2888     } else {
2889       gc_string.append("(Mixed)");
2890       verify_type = G1HeapVerifier::G1VerifyMixed;
2891     }
2892     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2893 
2894     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2895                                                                   workers()->active_workers(),
2896                                                                   Threads::number_of_non_daemon_threads());
2897     active_workers = workers()->update_active_workers(active_workers);
2898     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2899 
2900     G1MonitoringScope ms(g1mm(),
2901                          false /* full_gc */,
2902                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2903 
2904     G1HeapTransition heap_transition(this);
2905     size_t heap_used_bytes_before_gc = used();
2906 
2907     // Don't dynamically change the number of GC threads this early.  A value of
2908     // 0 is used to indicate serial work.  When parallel work is done,
2909     // it will be set.
2910 
2911     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2912       IsGCActiveMark x;
2913 
2914       gc_prologue(false);
2915 
2916       if (VerifyRememberedSets) {
2917         log_info(gc, verify)("[Verifying RemSets before GC]");
2918         VerifyRegionRemSetClosure v_cl;
2919         heap_region_iterate(&v_cl);
2920       }
2921 
2922       _verifier->verify_before_gc(verify_type);
2923 
2924       _verifier->check_bitmaps("GC Start");
2925 
2926 #if COMPILER2_OR_JVMCI
2927       DerivedPointerTable::clear();
2928 #endif
2929 
2930       // Please see comment in g1CollectedHeap.hpp and
2931       // G1CollectedHeap::ref_processing_init() to see how
2932       // reference processing currently works in G1.
2933 
2934       // Enable discovery in the STW reference processor
2935       _ref_processor_stw->enable_discovery();
2936 
2937       {
2938         // We want to temporarily turn off discovery by the
2939         // CM ref processor, if necessary, and turn it back on
2940         // on again later if we do. Using a scoped
2941         // NoRefDiscovery object will do this.
2942         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2943 
2944         // Forget the current alloc region (we might even choose it to be part
2945         // of the collection set!).
2946         _allocator->release_mutator_alloc_region();
2947 
2948         // This timing is only used by the ergonomics to handle our pause target.
2949         // It is unclear why this should not include the full pause. We will
2950         // investigate this in CR 7178365.
2951         //
2952         // Preserving the old comment here if that helps the investigation:
2953         //
2954         // The elapsed time induced by the start time below deliberately elides
2955         // the possible verification above.
2956         double sample_start_time_sec = os::elapsedTime();
2957 
2958         g1_policy()->record_collection_pause_start(sample_start_time_sec);
2959 
2960         if (collector_state()->in_initial_mark_gc()) {
2961           concurrent_mark()->pre_initial_mark();
2962         }
2963 
2964         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2965 
2966         evacuation_info.set_collectionset_regions(collection_set()->region_length());
2967 
2968         // Make sure the remembered sets are up to date. This needs to be
2969         // done before register_humongous_regions_with_cset(), because the
2970         // remembered sets are used there to choose eager reclaim candidates.
2971         // If the remembered sets are not up to date we might miss some
2972         // entries that need to be handled.
2973         g1_rem_set()->cleanupHRRS();
2974 
2975         register_humongous_regions_with_cset();
2976 
2977         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2978 
2979         // We call this after finalize_cset() to
2980         // ensure that the CSet has been finalized.
2981         _cm->verify_no_cset_oops();
2982 
2983         if (_hr_printer.is_active()) {
2984           G1PrintCollectionSetClosure cl(&_hr_printer);
2985           _collection_set.iterate(&cl);
2986         }
2987 
2988         // Initialize the GC alloc regions.
2989         _allocator->init_gc_alloc_regions(evacuation_info);
2990 
2991         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2992         pre_evacuate_collection_set();
2993 
2994         // Actually do the work...
2995         evacuate_collection_set(&per_thread_states);
2996 
2997         post_evacuate_collection_set(evacuation_info, &per_thread_states);
2998 
2999         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3000         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3001 
3002         eagerly_reclaim_humongous_regions();
3003 
3004         record_obj_copy_mem_stats();
3005         _survivor_evac_stats.adjust_desired_plab_sz();
3006         _old_evac_stats.adjust_desired_plab_sz();
3007 
3008         double start = os::elapsedTime();
3009         start_new_collection_set();
3010         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3011 
3012         if (evacuation_failed()) {
3013           double recalculate_used_start = os::elapsedTime();
3014           set_used(recalculate_used());
3015           g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3016 
3017           if (_archive_allocator != NULL) {
3018             _archive_allocator->clear_used();
3019           }
3020           for (uint i = 0; i < ParallelGCThreads; i++) {
3021             if (_evacuation_failed_info_array[i].has_failed()) {
3022               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3023             }
3024           }
3025         } else {
3026           // The "used" of the the collection set have already been subtracted
3027           // when they were freed.  Add in the bytes evacuated.
3028           increase_used(g1_policy()->bytes_copied_during_gc());
3029         }
3030 
3031         if (collector_state()->in_initial_mark_gc()) {
3032           // We have to do this before we notify the CM threads that
3033           // they can start working to make sure that all the
3034           // appropriate initialization is done on the CM object.
3035           concurrent_mark()->post_initial_mark();
3036           // Note that we don't actually trigger the CM thread at
3037           // this point. We do that later when we're sure that
3038           // the current thread has completed its logging output.
3039         }
3040 
3041         allocate_dummy_regions();
3042 
3043         _allocator->init_mutator_alloc_region();
3044 
3045         {
3046           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3047           if (expand_bytes > 0) {
3048             size_t bytes_before = capacity();
3049             // No need for an ergo logging here,
3050             // expansion_amount() does this when it returns a value > 0.
3051             double expand_ms;
3052             if (!expand(expand_bytes, _workers, &expand_ms)) {
3053               // We failed to expand the heap. Cannot do anything about it.
3054             }
3055             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3056           }
3057         }
3058 
3059         // We redo the verification but now wrt to the new CSet which
3060         // has just got initialized after the previous CSet was freed.
3061         _cm->verify_no_cset_oops();
3062 
3063         // This timing is only used by the ergonomics to handle our pause target.
3064         // It is unclear why this should not include the full pause. We will
3065         // investigate this in CR 7178365.
3066         double sample_end_time_sec = os::elapsedTime();
3067         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3068         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3069         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3070 
3071         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3072         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3073 
3074         if (VerifyRememberedSets) {
3075           log_info(gc, verify)("[Verifying RemSets after GC]");
3076           VerifyRegionRemSetClosure v_cl;
3077           heap_region_iterate(&v_cl);
3078         }
3079 
3080         _verifier->verify_after_gc(verify_type);
3081         _verifier->check_bitmaps("GC End");
3082 
3083         assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3084         _ref_processor_stw->verify_no_references_recorded();
3085 
3086         // CM reference discovery will be re-enabled if necessary.
3087       }
3088 
3089 #ifdef TRACESPINNING
3090       ParallelTaskTerminator::print_termination_counts();
3091 #endif
3092 
3093       gc_epilogue(false);
3094     }
3095 
3096     // Print the remainder of the GC log output.
3097     if (evacuation_failed()) {
3098       log_info(gc)("To-space exhausted");
3099     }
3100 
3101     g1_policy()->print_phases();
3102     heap_transition.print();
3103 
3104     // It is not yet to safe to tell the concurrent mark to
3105     // start as we have some optional output below. We don't want the
3106     // output from the concurrent mark thread interfering with this
3107     // logging output either.
3108 
3109     _hrm.verify_optional();
3110     _verifier->verify_region_sets_optional();
3111 
3112     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3113     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3114 
3115     print_heap_after_gc();
3116     print_heap_regions();
3117     trace_heap_after_gc(_gc_tracer_stw);
3118 
3119     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3120     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3121     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3122     // before any GC notifications are raised.
3123     g1mm()->update_sizes();
3124 
3125     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3126     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3127     _gc_timer_stw->register_gc_end();
3128     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3129   }
3130   // It should now be safe to tell the concurrent mark thread to start
3131   // without its logging output interfering with the logging output
3132   // that came from the pause.
3133 
3134   if (should_start_conc_mark) {
3135     // CAUTION: after the doConcurrentMark() call below,
3136     // the concurrent marking thread(s) could be running
3137     // concurrently with us. Make sure that anything after
3138     // this point does not assume that we are the only GC thread
3139     // running. Note: of course, the actual marking work will
3140     // not start until the safepoint itself is released in
3141     // SuspendibleThreadSet::desynchronize().
3142     do_concurrent_mark();
3143   }
3144 
3145   return true;
3146 }
3147 
3148 void G1CollectedHeap::remove_self_forwarding_pointers() {
3149   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3150   workers()->run_task(&rsfp_task);
3151 }
3152 
3153 void G1CollectedHeap::restore_after_evac_failure() {
3154   double remove_self_forwards_start = os::elapsedTime();
3155 
3156   remove_self_forwarding_pointers();
3157   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3158   _preserved_marks_set.restore(&task_executor);
3159 
3160   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3161 }
3162 
3163 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3164   if (!_evacuation_failed) {
3165     _evacuation_failed = true;
3166   }
3167 
3168   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3169   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3170 }
3171 
3172 bool G1ParEvacuateFollowersClosure::offer_termination() {
3173   EventGCPhaseParallel event;
3174   G1ParScanThreadState* const pss = par_scan_state();
3175   start_term_time();
3176   const bool res = terminator()->offer_termination();
3177   end_term_time();
3178   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3179   return res;
3180 }
3181 
3182 void G1ParEvacuateFollowersClosure::do_void() {
3183   EventGCPhaseParallel event;
3184   G1ParScanThreadState* const pss = par_scan_state();
3185   pss->trim_queue();
3186   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3187   do {
3188     EventGCPhaseParallel event;
3189     pss->steal_and_trim_queue(queues());
3190     event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3191   } while (!offer_termination());
3192 }
3193 
3194 class G1ParTask : public AbstractGangTask {
3195 protected:
3196   G1CollectedHeap*         _g1h;
3197   G1ParScanThreadStateSet* _pss;
3198   RefToScanQueueSet*       _queues;
3199   G1RootProcessor*         _root_processor;
3200   ParallelTaskTerminator   _terminator;
3201   uint                     _n_workers;
3202 
3203 public:
3204   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3205     : AbstractGangTask("G1 collection"),
3206       _g1h(g1h),
3207       _pss(per_thread_states),
3208       _queues(task_queues),
3209       _root_processor(root_processor),
3210       _terminator(n_workers, _queues),
3211       _n_workers(n_workers)
3212   {}
3213 
3214   void work(uint worker_id) {
3215     if (worker_id >= _n_workers) return;  // no work needed this round
3216 
3217     double start_sec = os::elapsedTime();
3218     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3219 
3220     {
3221       ResourceMark rm;
3222       HandleMark   hm;
3223 
3224       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3225 
3226       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3227       pss->set_ref_discoverer(rp);
3228 
3229       double start_strong_roots_sec = os::elapsedTime();
3230 
3231       _root_processor->evacuate_roots(pss, worker_id);
3232 
3233       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3234       // treating the nmethods visited to act as roots for concurrent marking.
3235       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3236       // objects copied by the current evacuation.
3237       _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3238 
3239       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3240 
3241       double term_sec = 0.0;
3242       size_t evac_term_attempts = 0;
3243       {
3244         double start = os::elapsedTime();
3245         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3246         evac.do_void();
3247 
3248         evac_term_attempts = evac.term_attempts();
3249         term_sec = evac.term_time();
3250         double elapsed_sec = os::elapsedTime() - start;
3251 
3252         G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3253         p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3254         p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3255         p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3256       }
3257 
3258       assert(pss->queue_is_empty(), "should be empty");
3259 
3260       if (log_is_enabled(Debug, gc, task, stats)) {
3261         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3262         size_t lab_waste;
3263         size_t lab_undo_waste;
3264         pss->waste(lab_waste, lab_undo_waste);
3265         _g1h->print_termination_stats(worker_id,
3266                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3267                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3268                                       term_sec * 1000.0,                          /* evac term time */
3269                                       evac_term_attempts,                         /* evac term attempts */
3270                                       lab_waste,                                  /* alloc buffer waste */
3271                                       lab_undo_waste                              /* undo waste */
3272                                       );
3273       }
3274 
3275       // Close the inner scope so that the ResourceMark and HandleMark
3276       // destructors are executed here and are included as part of the
3277       // "GC Worker Time".
3278     }
3279     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3280   }
3281 };
3282 
3283 void G1CollectedHeap::print_termination_stats_hdr() {
3284   log_debug(gc, task, stats)("GC Termination Stats");
3285   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3286   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3287   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3288 }
3289 
3290 void G1CollectedHeap::print_termination_stats(uint worker_id,
3291                                               double elapsed_ms,
3292                                               double strong_roots_ms,
3293                                               double term_ms,
3294                                               size_t term_attempts,
3295                                               size_t alloc_buffer_waste,
3296                                               size_t undo_waste) const {
3297   log_debug(gc, task, stats)
3298               ("%3d %9.2f %9.2f %6.2f "
3299                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3300                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3301                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3302                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3303                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3304                alloc_buffer_waste * HeapWordSize / K,
3305                undo_waste * HeapWordSize / K);
3306 }
3307 
3308 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3309                                         bool class_unloading_occurred) {
3310   uint n_workers = workers()->active_workers();
3311 
3312   G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3313   ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred);
3314   workers()->run_task(&g1_unlink_task);
3315 }
3316 
3317 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3318                                        bool process_strings,
3319                                        bool process_string_dedup) {
3320   if (!process_strings && !process_string_dedup) {
3321     // Nothing to clean.
3322     return;
3323   }
3324 
3325   G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3326   StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings);
3327   workers()->run_task(&g1_unlink_task);
3328 }
3329 
3330 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3331  private:
3332   DirtyCardQueueSet* _queue;
3333   G1CollectedHeap* _g1h;
3334  public:
3335   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3336     _queue(queue), _g1h(g1h) { }
3337 
3338   virtual void work(uint worker_id) {
3339     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3340     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3341 
3342     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3343     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3344 
3345     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3346   }
3347 };
3348 
3349 void G1CollectedHeap::redirty_logged_cards() {
3350   double redirty_logged_cards_start = os::elapsedTime();
3351 
3352   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3353   dirty_card_queue_set().reset_for_par_iteration();
3354   workers()->run_task(&redirty_task);
3355 
3356   DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3357   dcq.merge_bufferlists(&dirty_card_queue_set());
3358   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3359 
3360   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3361 }
3362 
3363 // Weak Reference Processing support
3364 
3365 bool G1STWIsAliveClosure::do_object_b(oop p) {
3366   // An object is reachable if it is outside the collection set,
3367   // or is inside and copied.
3368   return !_g1h->is_in_cset(p) || p->is_forwarded();
3369 }
3370 
3371 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3372   assert(obj != NULL, "must not be NULL");
3373   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3374   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3375   // may falsely indicate that this is not the case here: however the collection set only
3376   // contains old regions when concurrent mark is not running.
3377   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3378 }
3379 
3380 // Non Copying Keep Alive closure
3381 class G1KeepAliveClosure: public OopClosure {
3382   G1CollectedHeap*_g1h;
3383 public:
3384   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3385   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3386   void do_oop(oop* p) {
3387     oop obj = *p;
3388     assert(obj != NULL, "the caller should have filtered out NULL values");
3389 
3390     const InCSetState cset_state =_g1h->in_cset_state(obj);
3391     if (!cset_state.is_in_cset_or_humongous()) {
3392       return;
3393     }
3394     if (cset_state.is_in_cset()) {
3395       assert( obj->is_forwarded(), "invariant" );
3396       *p = obj->forwardee();
3397     } else {
3398       assert(!obj->is_forwarded(), "invariant" );
3399       assert(cset_state.is_humongous(),
3400              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3401      _g1h->set_humongous_is_live(obj);
3402     }
3403   }
3404 };
3405 
3406 // Copying Keep Alive closure - can be called from both
3407 // serial and parallel code as long as different worker
3408 // threads utilize different G1ParScanThreadState instances
3409 // and different queues.
3410 
3411 class G1CopyingKeepAliveClosure: public OopClosure {
3412   G1CollectedHeap*         _g1h;
3413   G1ParScanThreadState*    _par_scan_state;
3414 
3415 public:
3416   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3417                             G1ParScanThreadState* pss):
3418     _g1h(g1h),
3419     _par_scan_state(pss)
3420   {}
3421 
3422   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3423   virtual void do_oop(      oop* p) { do_oop_work(p); }
3424 
3425   template <class T> void do_oop_work(T* p) {
3426     oop obj = RawAccess<>::oop_load(p);
3427 
3428     if (_g1h->is_in_cset_or_humongous(obj)) {
3429       // If the referent object has been forwarded (either copied
3430       // to a new location or to itself in the event of an
3431       // evacuation failure) then we need to update the reference
3432       // field and, if both reference and referent are in the G1
3433       // heap, update the RSet for the referent.
3434       //
3435       // If the referent has not been forwarded then we have to keep
3436       // it alive by policy. Therefore we have copy the referent.
3437       //
3438       // When the queue is drained (after each phase of reference processing)
3439       // the object and it's followers will be copied, the reference field set
3440       // to point to the new location, and the RSet updated.
3441       _par_scan_state->push_on_queue(p);
3442     }
3443   }
3444 };
3445 
3446 // Serial drain queue closure. Called as the 'complete_gc'
3447 // closure for each discovered list in some of the
3448 // reference processing phases.
3449 
3450 class G1STWDrainQueueClosure: public VoidClosure {
3451 protected:
3452   G1CollectedHeap* _g1h;
3453   G1ParScanThreadState* _par_scan_state;
3454 
3455   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3456 
3457 public:
3458   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3459     _g1h(g1h),
3460     _par_scan_state(pss)
3461   { }
3462 
3463   void do_void() {
3464     G1ParScanThreadState* const pss = par_scan_state();
3465     pss->trim_queue();
3466   }
3467 };
3468 
3469 // Parallel Reference Processing closures
3470 
3471 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3472 // processing during G1 evacuation pauses.
3473 
3474 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3475 private:
3476   G1CollectedHeap*          _g1h;
3477   G1ParScanThreadStateSet*  _pss;
3478   RefToScanQueueSet*        _queues;
3479   WorkGang*                 _workers;
3480 
3481 public:
3482   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3483                            G1ParScanThreadStateSet* per_thread_states,
3484                            WorkGang* workers,
3485                            RefToScanQueueSet *task_queues) :
3486     _g1h(g1h),
3487     _pss(per_thread_states),
3488     _queues(task_queues),
3489     _workers(workers)
3490   {
3491     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3492   }
3493 
3494   // Executes the given task using concurrent marking worker threads.
3495   virtual void execute(ProcessTask& task, uint ergo_workers);
3496 };
3497 
3498 // Gang task for possibly parallel reference processing
3499 
3500 class G1STWRefProcTaskProxy: public AbstractGangTask {
3501   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3502   ProcessTask&     _proc_task;
3503   G1CollectedHeap* _g1h;
3504   G1ParScanThreadStateSet* _pss;
3505   RefToScanQueueSet* _task_queues;
3506   ParallelTaskTerminator* _terminator;
3507 
3508 public:
3509   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3510                         G1CollectedHeap* g1h,
3511                         G1ParScanThreadStateSet* per_thread_states,
3512                         RefToScanQueueSet *task_queues,
3513                         ParallelTaskTerminator* terminator) :
3514     AbstractGangTask("Process reference objects in parallel"),
3515     _proc_task(proc_task),
3516     _g1h(g1h),
3517     _pss(per_thread_states),
3518     _task_queues(task_queues),
3519     _terminator(terminator)
3520   {}
3521 
3522   virtual void work(uint worker_id) {
3523     // The reference processing task executed by a single worker.
3524     ResourceMark rm;
3525     HandleMark   hm;
3526 
3527     G1STWIsAliveClosure is_alive(_g1h);
3528 
3529     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3530     pss->set_ref_discoverer(NULL);
3531 
3532     // Keep alive closure.
3533     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3534 
3535     // Complete GC closure
3536     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3537 
3538     // Call the reference processing task's work routine.
3539     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3540 
3541     // Note we cannot assert that the refs array is empty here as not all
3542     // of the processing tasks (specifically phase2 - pp2_work) execute
3543     // the complete_gc closure (which ordinarily would drain the queue) so
3544     // the queue may not be empty.
3545   }
3546 };
3547 
3548 // Driver routine for parallel reference processing.
3549 // Creates an instance of the ref processing gang
3550 // task and has the worker threads execute it.
3551 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3552   assert(_workers != NULL, "Need parallel worker threads.");
3553 
3554   assert(_workers->active_workers() >= ergo_workers,
3555          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3556          ergo_workers, _workers->active_workers());
3557   ParallelTaskTerminator terminator(ergo_workers, _queues);
3558   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3559 
3560   _workers->run_task(&proc_task_proxy, ergo_workers);
3561 }
3562 
3563 // End of weak reference support closures
3564 
3565 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3566   double ref_proc_start = os::elapsedTime();
3567 
3568   ReferenceProcessor* rp = _ref_processor_stw;
3569   assert(rp->discovery_enabled(), "should have been enabled");
3570 
3571   // Closure to test whether a referent is alive.
3572   G1STWIsAliveClosure is_alive(this);
3573 
3574   // Even when parallel reference processing is enabled, the processing
3575   // of JNI refs is serial and performed serially by the current thread
3576   // rather than by a worker. The following PSS will be used for processing
3577   // JNI refs.
3578 
3579   // Use only a single queue for this PSS.
3580   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3581   pss->set_ref_discoverer(NULL);
3582   assert(pss->queue_is_empty(), "pre-condition");
3583 
3584   // Keep alive closure.
3585   G1CopyingKeepAliveClosure keep_alive(this, pss);
3586 
3587   // Serial Complete GC closure
3588   G1STWDrainQueueClosure drain_queue(this, pss);
3589 
3590   // Setup the soft refs policy...
3591   rp->setup_policy(false);
3592 
3593   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3594 
3595   ReferenceProcessorStats stats;
3596   if (!rp->processing_is_mt()) {
3597     // Serial reference processing...
3598     stats = rp->process_discovered_references(&is_alive,
3599                                               &keep_alive,
3600                                               &drain_queue,
3601                                               NULL,
3602                                               pt);
3603   } else {
3604     uint no_of_gc_workers = workers()->active_workers();
3605 
3606     // Parallel reference processing
3607     assert(no_of_gc_workers <= rp->max_num_queues(),
3608            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3609            no_of_gc_workers,  rp->max_num_queues());
3610 
3611     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3612     stats = rp->process_discovered_references(&is_alive,
3613                                               &keep_alive,
3614                                               &drain_queue,
3615                                               &par_task_executor,
3616                                               pt);
3617   }
3618 
3619   _gc_tracer_stw->report_gc_reference_stats(stats);
3620 
3621   // We have completed copying any necessary live referent objects.
3622   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3623 
3624   make_pending_list_reachable();
3625 
3626   rp->verify_no_references_recorded();
3627 
3628   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3629   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3630 }
3631 
3632 void G1CollectedHeap::make_pending_list_reachable() {
3633   if (collector_state()->in_initial_mark_gc()) {
3634     oop pll_head = Universe::reference_pending_list();
3635     if (pll_head != NULL) {
3636       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3637       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3638     }
3639   }
3640 }
3641 
3642 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3643   double merge_pss_time_start = os::elapsedTime();
3644   per_thread_states->flush();
3645   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3646 }
3647 
3648 void G1CollectedHeap::pre_evacuate_collection_set() {
3649   _expand_heap_after_alloc_failure = true;
3650   _evacuation_failed = false;
3651 
3652   // Disable the hot card cache.
3653   _hot_card_cache->reset_hot_cache_claimed_index();
3654   _hot_card_cache->set_use_cache(false);
3655 
3656   g1_rem_set()->prepare_for_oops_into_collection_set_do();
3657   _preserved_marks_set.assert_empty();
3658 
3659   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3660 
3661   // InitialMark needs claim bits to keep track of the marked-through CLDs.
3662   if (collector_state()->in_initial_mark_gc()) {
3663     double start_clear_claimed_marks = os::elapsedTime();
3664 
3665     ClassLoaderDataGraph::clear_claimed_marks();
3666 
3667     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3668     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3669   }
3670 }
3671 
3672 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3673   // Should G1EvacuationFailureALot be in effect for this GC?
3674   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3675 
3676   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3677 
3678   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3679 
3680   double start_par_time_sec = os::elapsedTime();
3681   double end_par_time_sec;
3682 
3683   {
3684     const uint n_workers = workers()->active_workers();
3685     G1RootProcessor root_processor(this, n_workers);
3686     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3687 
3688     print_termination_stats_hdr();
3689 
3690     workers()->run_task(&g1_par_task);
3691     end_par_time_sec = os::elapsedTime();
3692 
3693     // Closing the inner scope will execute the destructor
3694     // for the G1RootProcessor object. We record the current
3695     // elapsed time before closing the scope so that time
3696     // taken for the destructor is NOT included in the
3697     // reported parallel time.
3698   }
3699 
3700   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3701   phase_times->record_par_time(par_time_ms);
3702 
3703   double code_root_fixup_time_ms =
3704         (os::elapsedTime() - end_par_time_sec) * 1000.0;
3705   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
3706 }
3707 
3708 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3709   // Also cleans the card table from temporary duplicate detection information used
3710   // during UpdateRS/ScanRS.
3711   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
3712 
3713   // Process any discovered reference objects - we have
3714   // to do this _before_ we retire the GC alloc regions
3715   // as we may have to copy some 'reachable' referent
3716   // objects (and their reachable sub-graphs) that were
3717   // not copied during the pause.
3718   process_discovered_references(per_thread_states);
3719 
3720   // FIXME
3721   // CM's reference processing also cleans up the string table.
3722   // Should we do that here also? We could, but it is a serial operation
3723   // and could significantly increase the pause time.
3724 
3725   G1STWIsAliveClosure is_alive(this);
3726   G1KeepAliveClosure keep_alive(this);
3727 
3728   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3729                               g1_policy()->phase_times()->weak_phase_times());
3730 
3731   if (G1StringDedup::is_enabled()) {
3732     double fixup_start = os::elapsedTime();
3733 
3734     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
3735 
3736     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
3737     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
3738   }
3739 
3740   if (evacuation_failed()) {
3741     restore_after_evac_failure();
3742 
3743     // Reset the G1EvacuationFailureALot counters and flags
3744     // Note: the values are reset only when an actual
3745     // evacuation failure occurs.
3746     NOT_PRODUCT(reset_evacuation_should_fail();)
3747   }
3748 
3749   _preserved_marks_set.assert_empty();
3750 
3751   _allocator->release_gc_alloc_regions(evacuation_info);
3752 
3753   merge_per_thread_state_info(per_thread_states);
3754 
3755   // Reset and re-enable the hot card cache.
3756   // Note the counts for the cards in the regions in the
3757   // collection set are reset when the collection set is freed.
3758   _hot_card_cache->reset_hot_cache();
3759   _hot_card_cache->set_use_cache(true);
3760 
3761   purge_code_root_memory();
3762 
3763   redirty_logged_cards();
3764 #if COMPILER2_OR_JVMCI
3765   double start = os::elapsedTime();
3766   DerivedPointerTable::update_pointers();
3767   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3768 #endif
3769   g1_policy()->print_age_table();
3770 }
3771 
3772 void G1CollectedHeap::record_obj_copy_mem_stats() {
3773   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3774 
3775   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3776                                                create_g1_evac_summary(&_old_evac_stats));
3777 }
3778 
3779 void G1CollectedHeap::free_region(HeapRegion* hr,
3780                                   FreeRegionList* free_list,
3781                                   bool skip_remset,
3782                                   bool skip_hot_card_cache,
3783                                   bool locked) {
3784   assert(!hr->is_free(), "the region should not be free");
3785   assert(!hr->is_empty(), "the region should not be empty");
3786   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
3787   assert(free_list != NULL, "pre-condition");
3788 
3789   if (G1VerifyBitmaps) {
3790     MemRegion mr(hr->bottom(), hr->end());
3791     concurrent_mark()->clear_range_in_prev_bitmap(mr);
3792   }
3793 
3794   // Clear the card counts for this region.
3795   // Note: we only need to do this if the region is not young
3796   // (since we don't refine cards in young regions).
3797   if (!skip_hot_card_cache && !hr->is_young()) {
3798     _hot_card_cache->reset_card_counts(hr);
3799   }
3800   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3801   _g1_policy->remset_tracker()->update_at_free(hr);
3802   free_list->add_ordered(hr);
3803 }
3804 
3805 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3806                                             FreeRegionList* free_list) {
3807   assert(hr->is_humongous(), "this is only for humongous regions");
3808   assert(free_list != NULL, "pre-condition");
3809   hr->clear_humongous();
3810   free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3811 }
3812 
3813 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3814                                            const uint humongous_regions_removed) {
3815   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3816     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3817     _old_set.bulk_remove(old_regions_removed);
3818     _humongous_set.bulk_remove(humongous_regions_removed);
3819   }
3820 
3821 }
3822 
3823 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3824   assert(list != NULL, "list can't be null");
3825   if (!list->is_empty()) {
3826     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3827     _hrm.insert_list_into_free_list(list);
3828   }
3829 }
3830 
3831 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3832   decrease_used(bytes);
3833 }
3834 
3835 class G1FreeCollectionSetTask : public AbstractGangTask {
3836 private:
3837 
3838   // Closure applied to all regions in the collection set to do work that needs to
3839   // be done serially in a single thread.
3840   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3841   private:
3842     EvacuationInfo* _evacuation_info;
3843     const size_t* _surviving_young_words;
3844 
3845     // Bytes used in successfully evacuated regions before the evacuation.
3846     size_t _before_used_bytes;
3847     // Bytes used in unsucessfully evacuated regions before the evacuation
3848     size_t _after_used_bytes;
3849 
3850     size_t _bytes_allocated_in_old_since_last_gc;
3851 
3852     size_t _failure_used_words;
3853     size_t _failure_waste_words;
3854 
3855     FreeRegionList _local_free_list;
3856   public:
3857     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3858       HeapRegionClosure(),
3859       _evacuation_info(evacuation_info),
3860       _surviving_young_words(surviving_young_words),
3861       _before_used_bytes(0),
3862       _after_used_bytes(0),
3863       _bytes_allocated_in_old_since_last_gc(0),
3864       _failure_used_words(0),
3865       _failure_waste_words(0),
3866       _local_free_list("Local Region List for CSet Freeing") {
3867     }
3868 
3869     virtual bool do_heap_region(HeapRegion* r) {
3870       G1CollectedHeap* g1h = G1CollectedHeap::heap();
3871 
3872       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3873       g1h->clear_in_cset(r);
3874 
3875       if (r->is_young()) {
3876         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
3877                "Young index %d is wrong for region %u of type %s with %u young regions",
3878                r->young_index_in_cset(),
3879                r->hrm_index(),
3880                r->get_type_str(),
3881                g1h->collection_set()->young_region_length());
3882         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
3883         r->record_surv_words_in_group(words_survived);
3884       }
3885 
3886       if (!r->evacuation_failed()) {
3887         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
3888         _before_used_bytes += r->used();
3889         g1h->free_region(r,
3890                          &_local_free_list,
3891                          true, /* skip_remset */
3892                          true, /* skip_hot_card_cache */
3893                          true  /* locked */);
3894       } else {
3895         r->uninstall_surv_rate_group();
3896         r->set_young_index_in_cset(-1);
3897         r->set_evacuation_failed(false);
3898         // When moving a young gen region to old gen, we "allocate" that whole region
3899         // there. This is in addition to any already evacuated objects. Notify the
3900         // policy about that.
3901         // Old gen regions do not cause an additional allocation: both the objects
3902         // still in the region and the ones already moved are accounted for elsewhere.
3903         if (r->is_young()) {
3904           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
3905         }
3906         // The region is now considered to be old.
3907         r->set_old();
3908         // Do some allocation statistics accounting. Regions that failed evacuation
3909         // are always made old, so there is no need to update anything in the young
3910         // gen statistics, but we need to update old gen statistics.
3911         size_t used_words = r->marked_bytes() / HeapWordSize;
3912 
3913         _failure_used_words += used_words;
3914         _failure_waste_words += HeapRegion::GrainWords - used_words;
3915 
3916         g1h->old_set_add(r);
3917         _after_used_bytes += r->used();
3918       }
3919       return false;
3920     }
3921 
3922     void complete_work() {
3923       G1CollectedHeap* g1h = G1CollectedHeap::heap();
3924 
3925       _evacuation_info->set_regions_freed(_local_free_list.length());
3926       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
3927 
3928       g1h->prepend_to_freelist(&_local_free_list);
3929       g1h->decrement_summary_bytes(_before_used_bytes);
3930 
3931       G1Policy* policy = g1h->g1_policy();
3932       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
3933 
3934       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
3935     }
3936   };
3937 
3938   G1CollectionSet* _collection_set;
3939   G1SerialFreeCollectionSetClosure _cl;
3940   const size_t* _surviving_young_words;
3941 
3942   size_t _rs_lengths;
3943 
3944   volatile jint _serial_work_claim;
3945 
3946   struct WorkItem {
3947     uint region_idx;
3948     bool is_young;
3949     bool evacuation_failed;
3950 
3951     WorkItem(HeapRegion* r) {
3952       region_idx = r->hrm_index();
3953       is_young = r->is_young();
3954       evacuation_failed = r->evacuation_failed();
3955     }
3956   };
3957 
3958   volatile size_t _parallel_work_claim;
3959   size_t _num_work_items;
3960   WorkItem* _work_items;
3961 
3962   void do_serial_work() {
3963     // Need to grab the lock to be allowed to modify the old region list.
3964     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3965     _collection_set->iterate(&_cl);
3966   }
3967 
3968   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
3969     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3970 
3971     HeapRegion* r = g1h->region_at(region_idx);
3972     assert(!g1h->is_on_master_free_list(r), "sanity");
3973 
3974     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
3975 
3976     if (!is_young) {
3977       g1h->_hot_card_cache->reset_card_counts(r);
3978     }
3979 
3980     if (!evacuation_failed) {
3981       r->rem_set()->clear_locked();
3982     }
3983   }
3984 
3985   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
3986   private:
3987     size_t _cur_idx;
3988     WorkItem* _work_items;
3989   public:
3990     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
3991 
3992     virtual bool do_heap_region(HeapRegion* r) {
3993       _work_items[_cur_idx++] = WorkItem(r);
3994       return false;
3995     }
3996   };
3997 
3998   void prepare_work() {
3999     G1PrepareFreeCollectionSetClosure cl(_work_items);
4000     _collection_set->iterate(&cl);
4001   }
4002 
4003   void complete_work() {
4004     _cl.complete_work();
4005 
4006     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4007     policy->record_max_rs_lengths(_rs_lengths);
4008     policy->cset_regions_freed();
4009   }
4010 public:
4011   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4012     AbstractGangTask("G1 Free Collection Set"),
4013     _collection_set(collection_set),
4014     _cl(evacuation_info, surviving_young_words),
4015     _surviving_young_words(surviving_young_words),
4016     _rs_lengths(0),
4017     _serial_work_claim(0),
4018     _parallel_work_claim(0),
4019     _num_work_items(collection_set->region_length()),
4020     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4021     prepare_work();
4022   }
4023 
4024   ~G1FreeCollectionSetTask() {
4025     complete_work();
4026     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4027   }
4028 
4029   // Chunk size for work distribution. The chosen value has been determined experimentally
4030   // to be a good tradeoff between overhead and achievable parallelism.
4031   static uint chunk_size() { return 32; }
4032 
4033   virtual void work(uint worker_id) {
4034     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4035 
4036     // Claim serial work.
4037     if (_serial_work_claim == 0) {
4038       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4039       if (value == 0) {
4040         double serial_time = os::elapsedTime();
4041         do_serial_work();
4042         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4043       }
4044     }
4045 
4046     // Start parallel work.
4047     double young_time = 0.0;
4048     bool has_young_time = false;
4049     double non_young_time = 0.0;
4050     bool has_non_young_time = false;
4051 
4052     while (true) {
4053       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4054       size_t cur = end - chunk_size();
4055 
4056       if (cur >= _num_work_items) {
4057         break;
4058       }
4059 
4060       EventGCPhaseParallel event;
4061       double start_time = os::elapsedTime();
4062 
4063       end = MIN2(end, _num_work_items);
4064 
4065       for (; cur < end; cur++) {
4066         bool is_young = _work_items[cur].is_young;
4067 
4068         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4069 
4070         double end_time = os::elapsedTime();
4071         double time_taken = end_time - start_time;
4072         if (is_young) {
4073           young_time += time_taken;
4074           has_young_time = true;
4075           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4076         } else {
4077           non_young_time += time_taken;
4078           has_non_young_time = true;
4079           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4080         }
4081         start_time = end_time;
4082       }
4083     }
4084 
4085     if (has_young_time) {
4086       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4087     }
4088     if (has_non_young_time) {
4089       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4090     }
4091   }
4092 };
4093 
4094 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4095   _eden.clear();
4096 
4097   double free_cset_start_time = os::elapsedTime();
4098 
4099   {
4100     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4101     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4102 
4103     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4104 
4105     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4106                         cl.name(),
4107                         num_workers,
4108                         _collection_set.region_length());
4109     workers()->run_task(&cl, num_workers);
4110   }
4111   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4112 
4113   collection_set->clear();
4114 }
4115 
4116 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4117  private:
4118   FreeRegionList* _free_region_list;
4119   HeapRegionSet* _proxy_set;
4120   uint _humongous_objects_reclaimed;
4121   uint _humongous_regions_reclaimed;
4122   size_t _freed_bytes;
4123  public:
4124 
4125   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4126     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4127   }
4128 
4129   virtual bool do_heap_region(HeapRegion* r) {
4130     if (!r->is_starts_humongous()) {
4131       return false;
4132     }
4133 
4134     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4135 
4136     oop obj = (oop)r->bottom();
4137     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4138 
4139     // The following checks whether the humongous object is live are sufficient.
4140     // The main additional check (in addition to having a reference from the roots
4141     // or the young gen) is whether the humongous object has a remembered set entry.
4142     //
4143     // A humongous object cannot be live if there is no remembered set for it
4144     // because:
4145     // - there can be no references from within humongous starts regions referencing
4146     // the object because we never allocate other objects into them.
4147     // (I.e. there are no intra-region references that may be missed by the
4148     // remembered set)
4149     // - as soon there is a remembered set entry to the humongous starts region
4150     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4151     // until the end of a concurrent mark.
4152     //
4153     // It is not required to check whether the object has been found dead by marking
4154     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4155     // all objects allocated during that time are considered live.
4156     // SATB marking is even more conservative than the remembered set.
4157     // So if at this point in the collection there is no remembered set entry,
4158     // nobody has a reference to it.
4159     // At the start of collection we flush all refinement logs, and remembered sets
4160     // are completely up-to-date wrt to references to the humongous object.
4161     //
4162     // Other implementation considerations:
4163     // - never consider object arrays at this time because they would pose
4164     // considerable effort for cleaning up the the remembered sets. This is
4165     // required because stale remembered sets might reference locations that
4166     // are currently allocated into.
4167     uint region_idx = r->hrm_index();
4168     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4169         !r->rem_set()->is_empty()) {
4170       log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT "  with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
4171                                region_idx,
4172                                (size_t)obj->size() * HeapWordSize,
4173                                p2i(r->bottom()),
4174                                r->rem_set()->occupied(),
4175                                r->rem_set()->strong_code_roots_list_length(),
4176                                next_bitmap->is_marked(r->bottom()),
4177                                g1h->is_humongous_reclaim_candidate(region_idx),
4178                                obj->is_typeArray()
4179                               );
4180       return false;
4181     }
4182 
4183     guarantee(obj->is_typeArray(),
4184               "Only eagerly reclaiming type arrays is supported, but the object "
4185               PTR_FORMAT " is not.", p2i(r->bottom()));
4186 
4187     log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
4188                              region_idx,
4189                              (size_t)obj->size() * HeapWordSize,
4190                              p2i(r->bottom()),
4191                              r->rem_set()->occupied(),
4192                              r->rem_set()->strong_code_roots_list_length(),
4193                              next_bitmap->is_marked(r->bottom()),
4194                              g1h->is_humongous_reclaim_candidate(region_idx),
4195                              obj->is_typeArray()
4196                             );
4197 
4198     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4199     cm->humongous_object_eagerly_reclaimed(r);
4200     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4201            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4202            region_idx,
4203            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4204            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4205     _humongous_objects_reclaimed++;
4206     do {
4207       HeapRegion* next = g1h->next_region_in_humongous(r);
4208       _freed_bytes += r->used();
4209       r->set_containing_set(NULL);
4210       _humongous_regions_reclaimed++;
4211       g1h->free_humongous_region(r, _free_region_list);
4212       r = next;
4213     } while (r != NULL);
4214 
4215     return false;
4216   }
4217 
4218   uint humongous_objects_reclaimed() {
4219     return _humongous_objects_reclaimed;
4220   }
4221 
4222   uint humongous_regions_reclaimed() {
4223     return _humongous_regions_reclaimed;
4224   }
4225 
4226   size_t bytes_freed() const {
4227     return _freed_bytes;
4228   }
4229 };
4230 
4231 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4232   assert_at_safepoint_on_vm_thread();
4233 
4234   if (!G1EagerReclaimHumongousObjects ||
4235       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4236     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4237     return;
4238   }
4239 
4240   double start_time = os::elapsedTime();
4241 
4242   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4243 
4244   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4245   heap_region_iterate(&cl);
4246 
4247   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4248 
4249   G1HRPrinter* hrp = hr_printer();
4250   if (hrp->is_active()) {
4251     FreeRegionListIterator iter(&local_cleanup_list);
4252     while (iter.more_available()) {
4253       HeapRegion* hr = iter.get_next();
4254       hrp->cleanup(hr);
4255     }
4256   }
4257 
4258   prepend_to_freelist(&local_cleanup_list);
4259   decrement_summary_bytes(cl.bytes_freed());
4260 
4261   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4262                                                                     cl.humongous_objects_reclaimed());
4263 }
4264 
4265 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4266 public:
4267   virtual bool do_heap_region(HeapRegion* r) {
4268     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4269     G1CollectedHeap::heap()->clear_in_cset(r);
4270     r->set_young_index_in_cset(-1);
4271     return false;
4272   }
4273 };
4274 
4275 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4276   G1AbandonCollectionSetClosure cl;
4277   collection_set->iterate(&cl);
4278 
4279   collection_set->clear();
4280   collection_set->stop_incremental_building();
4281 }
4282 
4283 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4284   return _allocator->is_retained_old_region(hr);
4285 }
4286 
4287 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4288   _eden.add(hr);
4289   _g1_policy->set_region_eden(hr);
4290 }
4291 
4292 #ifdef ASSERT
4293 
4294 class NoYoungRegionsClosure: public HeapRegionClosure {
4295 private:
4296   bool _success;
4297 public:
4298   NoYoungRegionsClosure() : _success(true) { }
4299   bool do_heap_region(HeapRegion* r) {
4300     if (r->is_young()) {
4301       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4302                             p2i(r->bottom()), p2i(r->end()));
4303       _success = false;
4304     }
4305     return false;
4306   }
4307   bool success() { return _success; }
4308 };
4309 
4310 bool G1CollectedHeap::check_young_list_empty() {
4311   bool ret = (young_regions_count() == 0);
4312 
4313   NoYoungRegionsClosure closure;
4314   heap_region_iterate(&closure);
4315   ret = ret && closure.success();
4316 
4317   return ret;
4318 }
4319 
4320 #endif // ASSERT
4321 
4322 class TearDownRegionSetsClosure : public HeapRegionClosure {
4323   HeapRegionSet *_old_set;
4324 
4325 public:
4326   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4327 
4328   bool do_heap_region(HeapRegion* r) {
4329     if (r->is_old()) {
4330       _old_set->remove(r);
4331     } else if(r->is_young()) {
4332       r->uninstall_surv_rate_group();
4333     } else {
4334       // We ignore free regions, we'll empty the free list afterwards.
4335       // We ignore humongous and archive regions, we're not tearing down these
4336       // sets.
4337       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4338              "it cannot be another type");
4339     }
4340     return false;
4341   }
4342 
4343   ~TearDownRegionSetsClosure() {
4344     assert(_old_set->is_empty(), "post-condition");
4345   }
4346 };
4347 
4348 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4349   assert_at_safepoint_on_vm_thread();
4350 
4351   if (!free_list_only) {
4352     TearDownRegionSetsClosure cl(&_old_set);
4353     heap_region_iterate(&cl);
4354 
4355     // Note that emptying the _young_list is postponed and instead done as
4356     // the first step when rebuilding the regions sets again. The reason for
4357     // this is that during a full GC string deduplication needs to know if
4358     // a collected region was young or old when the full GC was initiated.
4359   }
4360   _hrm.remove_all_free_regions();
4361 }
4362 
4363 void G1CollectedHeap::increase_used(size_t bytes) {
4364   _summary_bytes_used += bytes;
4365 }
4366 
4367 void G1CollectedHeap::decrease_used(size_t bytes) {
4368   assert(_summary_bytes_used >= bytes,
4369          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4370          _summary_bytes_used, bytes);
4371   _summary_bytes_used -= bytes;
4372 }
4373 
4374 void G1CollectedHeap::set_used(size_t bytes) {
4375   _summary_bytes_used = bytes;
4376 }
4377 
4378 class RebuildRegionSetsClosure : public HeapRegionClosure {
4379 private:
4380   bool _free_list_only;
4381 
4382   HeapRegionSet* _old_set;
4383   HeapRegionManager* _hrm;
4384 
4385   size_t _total_used;
4386 
4387 public:
4388   RebuildRegionSetsClosure(bool free_list_only,
4389                            HeapRegionSet* old_set,
4390                            HeapRegionManager* hrm) :
4391     _free_list_only(free_list_only),
4392     _old_set(old_set), _hrm(hrm), _total_used(0) {
4393     assert(_hrm->num_free_regions() == 0, "pre-condition");
4394     if (!free_list_only) {
4395       assert(_old_set->is_empty(), "pre-condition");
4396     }
4397   }
4398 
4399   bool do_heap_region(HeapRegion* r) {
4400     // After full GC, no region should have a remembered set.
4401     r->rem_set()->clear(true);
4402     if (r->is_empty()) {
4403       // Add free regions to the free list
4404       r->set_free();
4405       _hrm->insert_into_free_list(r);
4406     } else if (!_free_list_only) {
4407 
4408       if (r->is_archive() || r->is_humongous()) {
4409         // We ignore archive and humongous regions. We left these sets unchanged.
4410       } else {
4411         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4412         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4413         r->move_to_old();
4414         _old_set->add(r);
4415       }
4416       _total_used += r->used();
4417     }
4418 
4419     return false;
4420   }
4421 
4422   size_t total_used() {
4423     return _total_used;
4424   }
4425 };
4426 
4427 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4428   assert_at_safepoint_on_vm_thread();
4429 
4430   if (!free_list_only) {
4431     _eden.clear();
4432     _survivor.clear();
4433   }
4434 
4435   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4436   heap_region_iterate(&cl);
4437 
4438   if (!free_list_only) {
4439     set_used(cl.total_used());
4440     if (_archive_allocator != NULL) {
4441       _archive_allocator->clear_used();
4442     }
4443   }
4444   assert(used_unlocked() == recalculate_used(),
4445          "inconsistent used_unlocked(), "
4446          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4447          used_unlocked(), recalculate_used());
4448 }
4449 
4450 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4451   HeapRegion* hr = heap_region_containing(p);
4452   return hr->is_in(p);
4453 }
4454 
4455 // Methods for the mutator alloc region
4456 
4457 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4458                                                       bool force) {
4459   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4460   bool should_allocate = g1_policy()->should_allocate_mutator_region();
4461   if (force || should_allocate) {
4462     HeapRegion* new_alloc_region = new_region(word_size,
4463                                               false /* is_old */,
4464                                               false /* do_expand */);
4465     if (new_alloc_region != NULL) {
4466       set_region_short_lived_locked(new_alloc_region);
4467       _hr_printer.alloc(new_alloc_region, !should_allocate);
4468       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4469       _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4470       return new_alloc_region;
4471     }
4472   }
4473   return NULL;
4474 }
4475 
4476 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4477                                                   size_t allocated_bytes) {
4478   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4479   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4480 
4481   collection_set()->add_eden_region(alloc_region);
4482   increase_used(allocated_bytes);
4483   _hr_printer.retire(alloc_region);
4484   // We update the eden sizes here, when the region is retired,
4485   // instead of when it's allocated, since this is the point that its
4486   // used space has been recorded in _summary_bytes_used.
4487   g1mm()->update_eden_size();
4488 }
4489 
4490 // Methods for the GC alloc regions
4491 
4492 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4493   if (dest.is_old()) {
4494     return true;
4495   } else {
4496     return survivor_regions_count() < g1_policy()->max_survivor_regions();
4497   }
4498 }
4499 
4500 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4501   assert(FreeList_lock->owned_by_self(), "pre-condition");
4502 
4503   if (!has_more_regions(dest)) {
4504     return NULL;
4505   }
4506 
4507   const bool is_survivor = dest.is_young();
4508 
4509   HeapRegion* new_alloc_region = new_region(word_size,
4510                                             !is_survivor,
4511                                             true /* do_expand */);
4512   if (new_alloc_region != NULL) {
4513     if (is_survivor) {
4514       new_alloc_region->set_survivor();
4515       _survivor.add(new_alloc_region);
4516       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4517     } else {
4518       new_alloc_region->set_old();
4519       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4520     }
4521     _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4522     _hr_printer.alloc(new_alloc_region);
4523     bool during_im = collector_state()->in_initial_mark_gc();
4524     new_alloc_region->note_start_of_copying(during_im);
4525     return new_alloc_region;
4526   }
4527   return NULL;
4528 }
4529 
4530 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4531                                              size_t allocated_bytes,
4532                                              InCSetState dest) {
4533   bool during_im = collector_state()->in_initial_mark_gc();
4534   alloc_region->note_end_of_copying(during_im);
4535   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4536   if (dest.is_old()) {
4537     old_set_add(alloc_region);
4538   }
4539   _hr_printer.retire(alloc_region);
4540 }
4541 
4542 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4543   bool expanded = false;
4544   uint index = _hrm.find_highest_free(&expanded);
4545 
4546   if (index != G1_NO_HRM_INDEX) {
4547     if (expanded) {
4548       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4549                                 HeapRegion::GrainWords * HeapWordSize);
4550     }
4551     _hrm.allocate_free_regions_starting_at(index, 1);
4552     return region_at(index);
4553   }
4554   return NULL;
4555 }
4556 
4557 // Optimized nmethod scanning
4558 
4559 class RegisterNMethodOopClosure: public OopClosure {
4560   G1CollectedHeap* _g1h;
4561   nmethod* _nm;
4562 
4563   template <class T> void do_oop_work(T* p) {
4564     T heap_oop = RawAccess<>::oop_load(p);
4565     if (!CompressedOops::is_null(heap_oop)) {
4566       oop obj = CompressedOops::decode_not_null(heap_oop);
4567       HeapRegion* hr = _g1h->heap_region_containing(obj);
4568       assert(!hr->is_continues_humongous(),
4569              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4570              " starting at " HR_FORMAT,
4571              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4572 
4573       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4574       hr->add_strong_code_root_locked(_nm);
4575     }
4576   }
4577 
4578 public:
4579   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4580     _g1h(g1h), _nm(nm) {}
4581 
4582   void do_oop(oop* p)       { do_oop_work(p); }
4583   void do_oop(narrowOop* p) { do_oop_work(p); }
4584 };
4585 
4586 class UnregisterNMethodOopClosure: public OopClosure {
4587   G1CollectedHeap* _g1h;
4588   nmethod* _nm;
4589 
4590   template <class T> void do_oop_work(T* p) {
4591     T heap_oop = RawAccess<>::oop_load(p);
4592     if (!CompressedOops::is_null(heap_oop)) {
4593       oop obj = CompressedOops::decode_not_null(heap_oop);
4594       HeapRegion* hr = _g1h->heap_region_containing(obj);
4595       assert(!hr->is_continues_humongous(),
4596              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4597              " starting at " HR_FORMAT,
4598              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4599 
4600       hr->remove_strong_code_root(_nm);
4601     }
4602   }
4603 
4604 public:
4605   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4606     _g1h(g1h), _nm(nm) {}
4607 
4608   void do_oop(oop* p)       { do_oop_work(p); }
4609   void do_oop(narrowOop* p) { do_oop_work(p); }
4610 };
4611 
4612 // Returns true if the reference points to an object that
4613 // can move in an incremental collection.
4614 bool G1CollectedHeap::is_scavengable(oop obj) {
4615   HeapRegion* hr = heap_region_containing(obj);
4616   return !hr->is_pinned();
4617 }
4618 
4619 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4620   guarantee(nm != NULL, "sanity");
4621   RegisterNMethodOopClosure reg_cl(this, nm);
4622   nm->oops_do(&reg_cl);
4623 }
4624 
4625 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4626   guarantee(nm != NULL, "sanity");
4627   UnregisterNMethodOopClosure reg_cl(this, nm);
4628   nm->oops_do(&reg_cl, true);
4629 }
4630 
4631 void G1CollectedHeap::purge_code_root_memory() {
4632   double purge_start = os::elapsedTime();
4633   G1CodeRootSet::purge();
4634   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4635   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4636 }
4637 
4638 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4639   G1CollectedHeap* _g1h;
4640 
4641 public:
4642   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4643     _g1h(g1h) {}
4644 
4645   void do_code_blob(CodeBlob* cb) {
4646     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4647     if (nm == NULL) {
4648       return;
4649     }
4650 
4651     if (ScavengeRootsInCode) {
4652       _g1h->register_nmethod(nm);
4653     }
4654   }
4655 };
4656 
4657 void G1CollectedHeap::rebuild_strong_code_roots() {
4658   RebuildStrongCodeRootClosure blob_cl(this);
4659   CodeCache::blobs_do(&blob_cl);
4660 }
4661 
4662 void G1CollectedHeap::initialize_serviceability() {
4663   _g1mm->initialize_serviceability();
4664 }
4665 
4666 MemoryUsage G1CollectedHeap::memory_usage() {
4667   return _g1mm->memory_usage();
4668 }
4669 
4670 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4671   return _g1mm->memory_managers();
4672 }
4673 
4674 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4675   return _g1mm->memory_pools();
4676 }