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/gcBehaviours.hpp"
  66 #include "gc/shared/gcHeapSummary.hpp"
  67 #include "gc/shared/gcId.hpp"
  68 #include "gc/shared/gcLocker.hpp"
  69 #include "gc/shared/gcTimer.hpp"
  70 #include "gc/shared/gcTrace.hpp"
  71 #include "gc/shared/gcTraceTime.inline.hpp"
  72 #include "gc/shared/generationSpec.hpp"
  73 #include "gc/shared/isGCActiveMark.hpp"
  74 #include "gc/shared/oopStorageParState.hpp"
  75 #include "gc/shared/parallelCleaning.hpp"
  76 #include "gc/shared/preservedMarks.inline.hpp"
  77 #include "gc/shared/suspendibleThreadSet.hpp"
  78 #include "gc/shared/referenceProcessor.inline.hpp"
  79 #include "gc/shared/taskqueue.inline.hpp"
  80 #include "gc/shared/weakProcessor.inline.hpp"
  81 #include "logging/log.hpp"
  82 #include "memory/allocation.hpp"
  83 #include "memory/iterator.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(G1ArchiveAllocator::is_archived_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_heap_if_necessary();
1048 
1049   // Rebuild the strong code root lists for each region
1050   rebuild_strong_code_roots();
1051 
1052   // Purge code root memory
1053   purge_code_root_memory();
1054 
1055   // Start a new incremental collection set for the next pause
1056   start_new_collection_set();
1057 
1058   _allocator->init_mutator_alloc_region();
1059 
1060   // Post collection state updates.
1061   MetaspaceGC::compute_new_size();
1062 }
1063 
1064 void G1CollectedHeap::abort_refinement() {
1065   if (_hot_card_cache->use_cache()) {
1066     _hot_card_cache->reset_hot_cache();
1067   }
1068 
1069   // Discard all remembered set updates.
1070   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1071   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1072 }
1073 
1074 void G1CollectedHeap::verify_after_full_collection() {
1075   _hrm.verify_optional();
1076   _verifier->verify_region_sets_optional();
1077   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1078   // Clear the previous marking bitmap, if needed for bitmap verification.
1079   // Note we cannot do this when we clear the next marking bitmap in
1080   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1081   // objects marked during a full GC against the previous bitmap.
1082   // But we need to clear it before calling check_bitmaps below since
1083   // the full GC has compacted objects and updated TAMS but not updated
1084   // the prev bitmap.
1085   if (G1VerifyBitmaps) {
1086     GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification");
1087     _cm->clear_prev_bitmap(workers());
1088   }
1089   // This call implicitly verifies that the next bitmap is clear after Full GC.
1090   _verifier->check_bitmaps("Full GC End");
1091 
1092   // At this point there should be no regions in the
1093   // entire heap tagged as young.
1094   assert(check_young_list_empty(), "young list should be empty at this point");
1095 
1096   // Note: since we've just done a full GC, concurrent
1097   // marking is no longer active. Therefore we need not
1098   // re-enable reference discovery for the CM ref processor.
1099   // That will be done at the start of the next marking cycle.
1100   // We also know that the STW processor should no longer
1101   // discover any new references.
1102   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1103   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1104   _ref_processor_stw->verify_no_references_recorded();
1105   _ref_processor_cm->verify_no_references_recorded();
1106 }
1107 
1108 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1109   // Post collection logging.
1110   // We should do this after we potentially resize the heap so
1111   // that all the COMMIT / UNCOMMIT events are generated before
1112   // the compaction events.
1113   print_hrm_post_compaction();
1114   heap_transition->print();
1115   print_heap_after_gc();
1116   print_heap_regions();
1117 #ifdef TRACESPINNING
1118   ParallelTaskTerminator::print_termination_counts();
1119 #endif
1120 }
1121 
1122 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1123                                          bool clear_all_soft_refs) {
1124   assert_at_safepoint_on_vm_thread();
1125 
1126   if (GCLocker::check_active_before_gc()) {
1127     // Full GC was not completed.
1128     return false;
1129   }
1130 
1131   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1132       soft_ref_policy()->should_clear_all_soft_refs();
1133 
1134   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1135   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1136 
1137   collector.prepare_collection();
1138   collector.collect();
1139   collector.complete_collection();
1140 
1141   // Full collection was successfully completed.
1142   return true;
1143 }
1144 
1145 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1146   // Currently, there is no facility in the do_full_collection(bool) API to notify
1147   // the caller that the collection did not succeed (e.g., because it was locked
1148   // out by the GC locker). So, right now, we'll ignore the return value.
1149   bool dummy = do_full_collection(true,                /* explicit_gc */
1150                                   clear_all_soft_refs);
1151 }
1152 
1153 void G1CollectedHeap::resize_heap_if_necessary() {
1154   // Capacity, free and used after the GC counted as full regions to
1155   // include the waste in the following calculations.
1156   const size_t capacity_after_gc = capacity();
1157   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1158 
1159   // This is enforced in arguments.cpp.
1160   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1161          "otherwise the code below doesn't make sense");
1162 
1163   // We don't have floating point command-line arguments
1164   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1165   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1166   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1167   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1168 
1169   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1170   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1171 
1172   // We have to be careful here as these two calculations can overflow
1173   // 32-bit size_t's.
1174   double used_after_gc_d = (double) used_after_gc;
1175   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1176   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1177 
1178   // Let's make sure that they are both under the max heap size, which
1179   // by default will make them fit into a size_t.
1180   double desired_capacity_upper_bound = (double) max_heap_size;
1181   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1182                                     desired_capacity_upper_bound);
1183   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1184                                     desired_capacity_upper_bound);
1185 
1186   // We can now safely turn them into size_t's.
1187   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1188   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1189 
1190   // This assert only makes sense here, before we adjust them
1191   // with respect to the min and max heap size.
1192   assert(minimum_desired_capacity <= maximum_desired_capacity,
1193          "minimum_desired_capacity = " SIZE_FORMAT ", "
1194          "maximum_desired_capacity = " SIZE_FORMAT,
1195          minimum_desired_capacity, maximum_desired_capacity);
1196 
1197   // Should not be greater than the heap max size. No need to adjust
1198   // it with respect to the heap min size as it's a lower bound (i.e.,
1199   // we'll try to make the capacity larger than it, not smaller).
1200   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1201   // Should not be less than the heap min size. No need to adjust it
1202   // with respect to the heap max size as it's an upper bound (i.e.,
1203   // we'll try to make the capacity smaller than it, not greater).
1204   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1205 
1206   if (capacity_after_gc < minimum_desired_capacity) {
1207     // Don't expand unless it's significant
1208     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1209 
1210     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1211                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1212                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1213                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1214 
1215     expand(expand_bytes, _workers);
1216 
1217     // No expansion, now see if we want to shrink
1218   } else if (capacity_after_gc > maximum_desired_capacity) {
1219     // Capacity too large, compute shrinking size
1220     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1221 
1222     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1223                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1224                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1225                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1226 
1227     shrink(shrink_bytes);
1228   }
1229 }
1230 
1231 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1232                                                             bool do_gc,
1233                                                             bool clear_all_soft_refs,
1234                                                             bool expect_null_mutator_alloc_region,
1235                                                             bool* gc_succeeded) {
1236   *gc_succeeded = true;
1237   // Let's attempt the allocation first.
1238   HeapWord* result =
1239     attempt_allocation_at_safepoint(word_size,
1240                                     expect_null_mutator_alloc_region);
1241   if (result != NULL) {
1242     return result;
1243   }
1244 
1245   // In a G1 heap, we're supposed to keep allocation from failing by
1246   // incremental pauses.  Therefore, at least for now, we'll favor
1247   // expansion over collection.  (This might change in the future if we can
1248   // do something smarter than full collection to satisfy a failed alloc.)
1249   result = expand_and_allocate(word_size);
1250   if (result != NULL) {
1251     return result;
1252   }
1253 
1254   if (do_gc) {
1255     // Expansion didn't work, we'll try to do a Full GC.
1256     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1257                                        clear_all_soft_refs);
1258   }
1259 
1260   return NULL;
1261 }
1262 
1263 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1264                                                      bool* succeeded) {
1265   assert_at_safepoint_on_vm_thread();
1266 
1267   // Attempts to allocate followed by Full GC.
1268   HeapWord* result =
1269     satisfy_failed_allocation_helper(word_size,
1270                                      true,  /* do_gc */
1271                                      false, /* clear_all_soft_refs */
1272                                      false, /* expect_null_mutator_alloc_region */
1273                                      succeeded);
1274 
1275   if (result != NULL || !*succeeded) {
1276     return result;
1277   }
1278 
1279   // Attempts to allocate followed by Full GC that will collect all soft references.
1280   result = satisfy_failed_allocation_helper(word_size,
1281                                             true, /* do_gc */
1282                                             true, /* clear_all_soft_refs */
1283                                             true, /* expect_null_mutator_alloc_region */
1284                                             succeeded);
1285 
1286   if (result != NULL || !*succeeded) {
1287     return result;
1288   }
1289 
1290   // Attempts to allocate, no GC
1291   result = satisfy_failed_allocation_helper(word_size,
1292                                             false, /* do_gc */
1293                                             false, /* clear_all_soft_refs */
1294                                             true,  /* expect_null_mutator_alloc_region */
1295                                             succeeded);
1296 
1297   if (result != NULL) {
1298     return result;
1299   }
1300 
1301   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1302          "Flag should have been handled and cleared prior to this point");
1303 
1304   // What else?  We might try synchronous finalization later.  If the total
1305   // space available is large enough for the allocation, then a more
1306   // complete compaction phase than we've tried so far might be
1307   // appropriate.
1308   return NULL;
1309 }
1310 
1311 // Attempting to expand the heap sufficiently
1312 // to support an allocation of the given "word_size".  If
1313 // successful, perform the allocation and return the address of the
1314 // allocated block, or else "NULL".
1315 
1316 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1317   assert_at_safepoint_on_vm_thread();
1318 
1319   _verifier->verify_region_sets_optional();
1320 
1321   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1322   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1323                             word_size * HeapWordSize);
1324 
1325 
1326   if (expand(expand_bytes, _workers)) {
1327     _hrm.verify_optional();
1328     _verifier->verify_region_sets_optional();
1329     return attempt_allocation_at_safepoint(word_size,
1330                                            false /* expect_null_mutator_alloc_region */);
1331   }
1332   return NULL;
1333 }
1334 
1335 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1336   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1337   aligned_expand_bytes = align_up(aligned_expand_bytes,
1338                                        HeapRegion::GrainBytes);
1339 
1340   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1341                             expand_bytes, aligned_expand_bytes);
1342 
1343   if (is_maximal_no_gc()) {
1344     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1345     return false;
1346   }
1347 
1348   double expand_heap_start_time_sec = os::elapsedTime();
1349   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1350   assert(regions_to_expand > 0, "Must expand by at least one region");
1351 
1352   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1353   if (expand_time_ms != NULL) {
1354     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1355   }
1356 
1357   if (expanded_by > 0) {
1358     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1359     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1360     g1_policy()->record_new_heap_size(num_regions());
1361   } else {
1362     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1363 
1364     // The expansion of the virtual storage space was unsuccessful.
1365     // Let's see if it was because we ran out of swap.
1366     if (G1ExitOnExpansionFailure &&
1367         _hrm.available() >= regions_to_expand) {
1368       // We had head room...
1369       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1370     }
1371   }
1372   return regions_to_expand > 0;
1373 }
1374 
1375 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1376   size_t aligned_shrink_bytes =
1377     ReservedSpace::page_align_size_down(shrink_bytes);
1378   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1379                                          HeapRegion::GrainBytes);
1380   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1381 
1382   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1383   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1384 
1385 
1386   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",
1387                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1388   if (num_regions_removed > 0) {
1389     g1_policy()->record_new_heap_size(num_regions());
1390   } else {
1391     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1392   }
1393 }
1394 
1395 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1396   _verifier->verify_region_sets_optional();
1397 
1398   // We should only reach here at the end of a Full GC or during Remark which
1399   // means we should not not be holding to any GC alloc regions. The method
1400   // below will make sure of that and do any remaining clean up.
1401   _allocator->abandon_gc_alloc_regions();
1402 
1403   // Instead of tearing down / rebuilding the free lists here, we
1404   // could instead use the remove_all_pending() method on free_list to
1405   // remove only the ones that we need to remove.
1406   tear_down_region_sets(true /* free_list_only */);
1407   shrink_helper(shrink_bytes);
1408   rebuild_region_sets(true /* free_list_only */);
1409 
1410   _hrm.verify_optional();
1411   _verifier->verify_region_sets_optional();
1412 }
1413 
1414 class OldRegionSetChecker : public HeapRegionSetChecker {
1415 public:
1416   void check_mt_safety() {
1417     // Master Old Set MT safety protocol:
1418     // (a) If we're at a safepoint, operations on the master old set
1419     // should be invoked:
1420     // - by the VM thread (which will serialize them), or
1421     // - by the GC workers while holding the FreeList_lock, if we're
1422     //   at a safepoint for an evacuation pause (this lock is taken
1423     //   anyway when an GC alloc region is retired so that a new one
1424     //   is allocated from the free list), or
1425     // - by the GC workers while holding the OldSets_lock, if we're at a
1426     //   safepoint for a cleanup pause.
1427     // (b) If we're not at a safepoint, operations on the master old set
1428     // should be invoked while holding the Heap_lock.
1429 
1430     if (SafepointSynchronize::is_at_safepoint()) {
1431       guarantee(Thread::current()->is_VM_thread() ||
1432                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1433                 "master old set MT safety protocol at a safepoint");
1434     } else {
1435       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1436     }
1437   }
1438   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1439   const char* get_description() { return "Old Regions"; }
1440 };
1441 
1442 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1443 public:
1444   void check_mt_safety() {
1445     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1446               "May only change archive regions during initialization or safepoint.");
1447   }
1448   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1449   const char* get_description() { return "Archive Regions"; }
1450 };
1451 
1452 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1453 public:
1454   void check_mt_safety() {
1455     // Humongous Set MT safety protocol:
1456     // (a) If we're at a safepoint, operations on the master humongous
1457     // set should be invoked by either the VM thread (which will
1458     // serialize them) or by the GC workers while holding the
1459     // OldSets_lock.
1460     // (b) If we're not at a safepoint, operations on the master
1461     // humongous set should be invoked while holding the Heap_lock.
1462 
1463     if (SafepointSynchronize::is_at_safepoint()) {
1464       guarantee(Thread::current()->is_VM_thread() ||
1465                 OldSets_lock->owned_by_self(),
1466                 "master humongous set MT safety protocol at a safepoint");
1467     } else {
1468       guarantee(Heap_lock->owned_by_self(),
1469                 "master humongous set MT safety protocol outside a safepoint");
1470     }
1471   }
1472   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1473   const char* get_description() { return "Humongous Regions"; }
1474 };
1475 
1476 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1477   CollectedHeap(),
1478   _young_gen_sampling_thread(NULL),
1479   _workers(NULL),
1480   _collector_policy(collector_policy),
1481   _card_table(NULL),
1482   _soft_ref_policy(),
1483   _old_set("Old Region Set", new OldRegionSetChecker()),
1484   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1485   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1486   _bot(NULL),
1487   _listener(),
1488   _hrm(),
1489   _allocator(NULL),
1490   _verifier(NULL),
1491   _summary_bytes_used(0),
1492   _archive_allocator(NULL),
1493   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1494   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1495   _expand_heap_after_alloc_failure(true),
1496   _g1mm(NULL),
1497   _humongous_reclaim_candidates(),
1498   _has_humongous_reclaim_candidates(false),
1499   _hr_printer(),
1500   _collector_state(),
1501   _old_marking_cycles_started(0),
1502   _old_marking_cycles_completed(0),
1503   _eden(),
1504   _survivor(),
1505   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1506   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1507   _g1_policy(new G1Policy(_gc_timer_stw)),
1508   _heap_sizing_policy(NULL),
1509   _collection_set(this, _g1_policy),
1510   _hot_card_cache(NULL),
1511   _g1_rem_set(NULL),
1512   _dirty_card_queue_set(false),
1513   _cm(NULL),
1514   _cm_thread(NULL),
1515   _cr(NULL),
1516   _task_queues(NULL),
1517   _evacuation_failed(false),
1518   _evacuation_failed_info_array(NULL),
1519   _preserved_marks_set(true /* in_c_heap */),
1520 #ifndef PRODUCT
1521   _evacuation_failure_alot_for_current_gc(false),
1522   _evacuation_failure_alot_gc_number(0),
1523   _evacuation_failure_alot_count(0),
1524 #endif
1525   _ref_processor_stw(NULL),
1526   _is_alive_closure_stw(this),
1527   _is_subject_to_discovery_stw(this),
1528   _ref_processor_cm(NULL),
1529   _is_alive_closure_cm(this),
1530   _is_subject_to_discovery_cm(this),
1531   _in_cset_fast_test() {
1532 
1533   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1534                           true /* are_GC_task_threads */,
1535                           false /* are_ConcurrentGC_threads */);
1536   _workers->initialize_workers();
1537   _verifier = new G1HeapVerifier(this);
1538 
1539   _allocator = new G1Allocator(this);
1540 
1541   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1542 
1543   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1544 
1545   // Override the default _filler_array_max_size so that no humongous filler
1546   // objects are created.
1547   _filler_array_max_size = _humongous_object_threshold_in_words;
1548 
1549   uint n_queues = ParallelGCThreads;
1550   _task_queues = new RefToScanQueueSet(n_queues);
1551 
1552   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1553 
1554   for (uint i = 0; i < n_queues; i++) {
1555     RefToScanQueue* q = new RefToScanQueue();
1556     q->initialize();
1557     _task_queues->register_queue(i, q);
1558     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1559   }
1560 
1561   // Initialize the G1EvacuationFailureALot counters and flags.
1562   NOT_PRODUCT(reset_evacuation_should_fail();)
1563 
1564   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1565 }
1566 
1567 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1568                                                                  size_t size,
1569                                                                  size_t translation_factor) {
1570   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1571   // Allocate a new reserved space, preferring to use large pages.
1572   ReservedSpace rs(size, preferred_page_size);
1573   size_t page_size = rs.actual_page_size();
1574   G1RegionToSpaceMapper* result  =
1575     G1RegionToSpaceMapper::create_mapper(rs,
1576                                          size,
1577                                          page_size,
1578                                          HeapRegion::GrainBytes,
1579                                          translation_factor,
1580                                          mtGC);
1581 
1582   os::trace_page_sizes_for_requested_size(description,
1583                                           size,
1584                                           preferred_page_size,
1585                                           page_size,
1586                                           rs.base(),
1587                                           rs.size());
1588 
1589   return result;
1590 }
1591 
1592 jint G1CollectedHeap::initialize_concurrent_refinement() {
1593   jint ecode = JNI_OK;
1594   _cr = G1ConcurrentRefine::create(&ecode);
1595   return ecode;
1596 }
1597 
1598 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1599   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1600   if (_young_gen_sampling_thread->osthread() == NULL) {
1601     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1602     return JNI_ENOMEM;
1603   }
1604   return JNI_OK;
1605 }
1606 
1607 jint G1CollectedHeap::initialize() {
1608   os::enable_vtime();
1609 
1610   // Necessary to satisfy locking discipline assertions.
1611 
1612   MutexLocker x(Heap_lock);
1613 
1614   // While there are no constraints in the GC code that HeapWordSize
1615   // be any particular value, there are multiple other areas in the
1616   // system which believe this to be true (e.g. oop->object_size in some
1617   // cases incorrectly returns the size in wordSize units rather than
1618   // HeapWordSize).
1619   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1620 
1621   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1622   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1623   size_t heap_alignment = collector_policy()->heap_alignment();
1624 
1625   // Ensure that the sizes are properly aligned.
1626   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1627   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1628   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1629 
1630   // Reserve the maximum.
1631 
1632   // When compressed oops are enabled, the preferred heap base
1633   // is calculated by subtracting the requested size from the
1634   // 32Gb boundary and using the result as the base address for
1635   // heap reservation. If the requested size is not aligned to
1636   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1637   // into the ReservedHeapSpace constructor) then the actual
1638   // base of the reserved heap may end up differing from the
1639   // address that was requested (i.e. the preferred heap base).
1640   // If this happens then we could end up using a non-optimal
1641   // compressed oops mode.
1642 
1643   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1644                                                  heap_alignment);
1645 
1646   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1647 
1648   // Create the barrier set for the entire reserved region.
1649   G1CardTable* ct = new G1CardTable(reserved_region());
1650   ct->initialize();
1651   G1BarrierSet* bs = new G1BarrierSet(ct);
1652   bs->initialize();
1653   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1654   BarrierSet::set_barrier_set(bs);
1655   _card_table = ct;
1656 
1657   // Create the hot card cache.
1658   _hot_card_cache = new G1HotCardCache(this);
1659 
1660   // Carve out the G1 part of the heap.
1661   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1662   size_t page_size = heap_rs.actual_page_size();
1663   G1RegionToSpaceMapper* heap_storage =
1664     G1RegionToSpaceMapper::create_mapper(g1_rs,
1665                                          g1_rs.size(),
1666                                          page_size,
1667                                          HeapRegion::GrainBytes,
1668                                          1,
1669                                          mtJavaHeap);
1670   os::trace_page_sizes("Heap",
1671                        collector_policy()->min_heap_byte_size(),
1672                        max_byte_size,
1673                        page_size,
1674                        heap_rs.base(),
1675                        heap_rs.size());
1676   heap_storage->set_mapping_changed_listener(&_listener);
1677 
1678   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1679   G1RegionToSpaceMapper* bot_storage =
1680     create_aux_memory_mapper("Block Offset Table",
1681                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1682                              G1BlockOffsetTable::heap_map_factor());
1683 
1684   G1RegionToSpaceMapper* cardtable_storage =
1685     create_aux_memory_mapper("Card Table",
1686                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1687                              G1CardTable::heap_map_factor());
1688 
1689   G1RegionToSpaceMapper* card_counts_storage =
1690     create_aux_memory_mapper("Card Counts Table",
1691                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1692                              G1CardCounts::heap_map_factor());
1693 
1694   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1695   G1RegionToSpaceMapper* prev_bitmap_storage =
1696     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1697   G1RegionToSpaceMapper* next_bitmap_storage =
1698     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1699 
1700   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1701   _card_table->initialize(cardtable_storage);
1702   // Do later initialization work for concurrent refinement.
1703   _hot_card_cache->initialize(card_counts_storage);
1704 
1705   // 6843694 - ensure that the maximum region index can fit
1706   // in the remembered set structures.
1707   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1708   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1709 
1710   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1711   // start within the first card.
1712   guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1713   // Also create a G1 rem set.
1714   _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1715   _g1_rem_set->initialize(max_capacity(), max_regions());
1716 
1717   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1718   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1719   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1720             "too many cards per region");
1721 
1722   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1723 
1724   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1725 
1726   {
1727     HeapWord* start = _hrm.reserved().start();
1728     HeapWord* end = _hrm.reserved().end();
1729     size_t granularity = HeapRegion::GrainBytes;
1730 
1731     _in_cset_fast_test.initialize(start, end, granularity);
1732     _humongous_reclaim_candidates.initialize(start, end, granularity);
1733   }
1734 
1735   // Create the G1ConcurrentMark data structure and thread.
1736   // (Must do this late, so that "max_regions" is defined.)
1737   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1738   if (_cm == NULL || !_cm->completed_initialization()) {
1739     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1740     return JNI_ENOMEM;
1741   }
1742   _cm_thread = _cm->cm_thread();
1743 
1744   // Now expand into the initial heap size.
1745   if (!expand(init_byte_size, _workers)) {
1746     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1747     return JNI_ENOMEM;
1748   }
1749 
1750   // Perform any initialization actions delegated to the policy.
1751   g1_policy()->init(this, &_collection_set);
1752 
1753   G1BarrierSet::satb_mark_queue_set().initialize(this,
1754                                                  SATB_Q_CBL_mon,
1755                                                  SATB_Q_FL_lock,
1756                                                  G1SATBProcessCompletedThreshold,
1757                                                  G1SATBBufferEnqueueingThresholdPercent,
1758                                                  Shared_SATB_Q_lock);
1759 
1760   jint ecode = initialize_concurrent_refinement();
1761   if (ecode != JNI_OK) {
1762     return ecode;
1763   }
1764 
1765   ecode = initialize_young_gen_sampling_thread();
1766   if (ecode != JNI_OK) {
1767     return ecode;
1768   }
1769 
1770   G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1771                                                   DirtyCardQ_FL_lock,
1772                                                   (int)concurrent_refine()->yellow_zone(),
1773                                                   (int)concurrent_refine()->red_zone(),
1774                                                   Shared_DirtyCardQ_lock,
1775                                                   NULL,  // fl_owner
1776                                                   true); // init_free_ids
1777 
1778   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1779                                     DirtyCardQ_FL_lock,
1780                                     -1, // never trigger processing
1781                                     -1, // no limit on length
1782                                     Shared_DirtyCardQ_lock,
1783                                     &G1BarrierSet::dirty_card_queue_set());
1784 
1785   // Here we allocate the dummy HeapRegion that is required by the
1786   // G1AllocRegion class.
1787   HeapRegion* dummy_region = _hrm.get_dummy_region();
1788 
1789   // We'll re-use the same region whether the alloc region will
1790   // require BOT updates or not and, if it doesn't, then a non-young
1791   // region will complain that it cannot support allocations without
1792   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1793   dummy_region->set_eden();
1794   // Make sure it's full.
1795   dummy_region->set_top(dummy_region->end());
1796   G1AllocRegion::setup(this, dummy_region);
1797 
1798   _allocator->init_mutator_alloc_region();
1799 
1800   // Do create of the monitoring and management support so that
1801   // values in the heap have been properly initialized.
1802   _g1mm = new G1MonitoringSupport(this);
1803 
1804   G1StringDedup::initialize();
1805 
1806   _preserved_marks_set.init(ParallelGCThreads);
1807 
1808   _collection_set.initialize(max_regions());
1809 
1810   return JNI_OK;
1811 }
1812 
1813 void G1CollectedHeap::stop() {
1814   // Stop all concurrent threads. We do this to make sure these threads
1815   // do not continue to execute and access resources (e.g. logging)
1816   // that are destroyed during shutdown.
1817   _cr->stop();
1818   _young_gen_sampling_thread->stop();
1819   _cm_thread->stop();
1820   if (G1StringDedup::is_enabled()) {
1821     G1StringDedup::stop();
1822   }
1823 }
1824 
1825 void G1CollectedHeap::safepoint_synchronize_begin() {
1826   SuspendibleThreadSet::synchronize();
1827 }
1828 
1829 void G1CollectedHeap::safepoint_synchronize_end() {
1830   SuspendibleThreadSet::desynchronize();
1831 }
1832 
1833 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1834   return HeapRegion::max_region_size();
1835 }
1836 
1837 void G1CollectedHeap::post_initialize() {
1838   CollectedHeap::post_initialize();
1839   ref_processing_init();
1840 }
1841 
1842 void G1CollectedHeap::ref_processing_init() {
1843   // Reference processing in G1 currently works as follows:
1844   //
1845   // * There are two reference processor instances. One is
1846   //   used to record and process discovered references
1847   //   during concurrent marking; the other is used to
1848   //   record and process references during STW pauses
1849   //   (both full and incremental).
1850   // * Both ref processors need to 'span' the entire heap as
1851   //   the regions in the collection set may be dotted around.
1852   //
1853   // * For the concurrent marking ref processor:
1854   //   * Reference discovery is enabled at initial marking.
1855   //   * Reference discovery is disabled and the discovered
1856   //     references processed etc during remarking.
1857   //   * Reference discovery is MT (see below).
1858   //   * Reference discovery requires a barrier (see below).
1859   //   * Reference processing may or may not be MT
1860   //     (depending on the value of ParallelRefProcEnabled
1861   //     and ParallelGCThreads).
1862   //   * A full GC disables reference discovery by the CM
1863   //     ref processor and abandons any entries on it's
1864   //     discovered lists.
1865   //
1866   // * For the STW processor:
1867   //   * Non MT discovery is enabled at the start of a full GC.
1868   //   * Processing and enqueueing during a full GC is non-MT.
1869   //   * During a full GC, references are processed after marking.
1870   //
1871   //   * Discovery (may or may not be MT) is enabled at the start
1872   //     of an incremental evacuation pause.
1873   //   * References are processed near the end of a STW evacuation pause.
1874   //   * For both types of GC:
1875   //     * Discovery is atomic - i.e. not concurrent.
1876   //     * Reference discovery will not need a barrier.
1877 
1878   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1879 
1880   // Concurrent Mark ref processor
1881   _ref_processor_cm =
1882     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1883                            mt_processing,                                  // mt processing
1884                            ParallelGCThreads,                              // degree of mt processing
1885                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1886                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1887                            false,                                          // Reference discovery is not atomic
1888                            &_is_alive_closure_cm,                          // is alive closure
1889                            true);                                          // allow changes to number of processing threads
1890 
1891   // STW ref processor
1892   _ref_processor_stw =
1893     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1894                            mt_processing,                        // mt processing
1895                            ParallelGCThreads,                    // degree of mt processing
1896                            (ParallelGCThreads > 1),              // mt discovery
1897                            ParallelGCThreads,                    // degree of mt discovery
1898                            true,                                 // Reference discovery is atomic
1899                            &_is_alive_closure_stw,               // is alive closure
1900                            true);                                // allow changes to number of processing threads
1901 }
1902 
1903 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1904   return _collector_policy;
1905 }
1906 
1907 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1908   return &_soft_ref_policy;
1909 }
1910 
1911 size_t G1CollectedHeap::capacity() const {
1912   return _hrm.length() * HeapRegion::GrainBytes;
1913 }
1914 
1915 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1916   return _hrm.total_free_bytes();
1917 }
1918 
1919 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1920   _hot_card_cache->drain(cl, worker_i);
1921 }
1922 
1923 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1924   DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1925   size_t n_completed_buffers = 0;
1926   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1927     n_completed_buffers++;
1928   }
1929   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1930   dcqs.clear_n_completed_buffers();
1931   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1932 }
1933 
1934 // Computes the sum of the storage used by the various regions.
1935 size_t G1CollectedHeap::used() const {
1936   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1937   if (_archive_allocator != NULL) {
1938     result += _archive_allocator->used();
1939   }
1940   return result;
1941 }
1942 
1943 size_t G1CollectedHeap::used_unlocked() const {
1944   return _summary_bytes_used;
1945 }
1946 
1947 class SumUsedClosure: public HeapRegionClosure {
1948   size_t _used;
1949 public:
1950   SumUsedClosure() : _used(0) {}
1951   bool do_heap_region(HeapRegion* r) {
1952     _used += r->used();
1953     return false;
1954   }
1955   size_t result() { return _used; }
1956 };
1957 
1958 size_t G1CollectedHeap::recalculate_used() const {
1959   SumUsedClosure blk;
1960   heap_region_iterate(&blk);
1961   return blk.result();
1962 }
1963 
1964 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1965   switch (cause) {
1966     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1967     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1968     case GCCause::_wb_conc_mark:                        return true;
1969     default :                                           return false;
1970   }
1971 }
1972 
1973 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1974   switch (cause) {
1975     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
1976     case GCCause::_g1_humongous_allocation: return true;
1977     default:                                return is_user_requested_concurrent_full_gc(cause);
1978   }
1979 }
1980 
1981 #ifndef PRODUCT
1982 void G1CollectedHeap::allocate_dummy_regions() {
1983   // Let's fill up most of the region
1984   size_t word_size = HeapRegion::GrainWords - 1024;
1985   // And as a result the region we'll allocate will be humongous.
1986   guarantee(is_humongous(word_size), "sanity");
1987 
1988   // _filler_array_max_size is set to humongous object threshold
1989   // but temporarily change it to use CollectedHeap::fill_with_object().
1990   SizeTFlagSetting fs(_filler_array_max_size, word_size);
1991 
1992   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1993     // Let's use the existing mechanism for the allocation
1994     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1995     if (dummy_obj != NULL) {
1996       MemRegion mr(dummy_obj, word_size);
1997       CollectedHeap::fill_with_object(mr);
1998     } else {
1999       // If we can't allocate once, we probably cannot allocate
2000       // again. Let's get out of the loop.
2001       break;
2002     }
2003   }
2004 }
2005 #endif // !PRODUCT
2006 
2007 void G1CollectedHeap::increment_old_marking_cycles_started() {
2008   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2009          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2010          "Wrong marking cycle count (started: %d, completed: %d)",
2011          _old_marking_cycles_started, _old_marking_cycles_completed);
2012 
2013   _old_marking_cycles_started++;
2014 }
2015 
2016 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2017   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2018 
2019   // We assume that if concurrent == true, then the caller is a
2020   // concurrent thread that was joined the Suspendible Thread
2021   // Set. If there's ever a cheap way to check this, we should add an
2022   // assert here.
2023 
2024   // Given that this method is called at the end of a Full GC or of a
2025   // concurrent cycle, and those can be nested (i.e., a Full GC can
2026   // interrupt a concurrent cycle), the number of full collections
2027   // completed should be either one (in the case where there was no
2028   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2029   // behind the number of full collections started.
2030 
2031   // This is the case for the inner caller, i.e. a Full GC.
2032   assert(concurrent ||
2033          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2034          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2035          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2036          "is inconsistent with _old_marking_cycles_completed = %u",
2037          _old_marking_cycles_started, _old_marking_cycles_completed);
2038 
2039   // This is the case for the outer caller, i.e. the concurrent cycle.
2040   assert(!concurrent ||
2041          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2042          "for outer caller (concurrent cycle): "
2043          "_old_marking_cycles_started = %u "
2044          "is inconsistent with _old_marking_cycles_completed = %u",
2045          _old_marking_cycles_started, _old_marking_cycles_completed);
2046 
2047   _old_marking_cycles_completed += 1;
2048 
2049   // We need to clear the "in_progress" flag in the CM thread before
2050   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2051   // is set) so that if a waiter requests another System.gc() it doesn't
2052   // incorrectly see that a marking cycle is still in progress.
2053   if (concurrent) {
2054     _cm_thread->set_idle();
2055   }
2056 
2057   // This notify_all() will ensure that a thread that called
2058   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2059   // and it's waiting for a full GC to finish will be woken up. It is
2060   // waiting in VM_G1CollectForAllocation::doit_epilogue().
2061   FullGCCount_lock->notify_all();
2062 }
2063 
2064 void G1CollectedHeap::collect(GCCause::Cause cause) {
2065   assert_heap_not_locked();
2066 
2067   uint gc_count_before;
2068   uint old_marking_count_before;
2069   uint full_gc_count_before;
2070   bool retry_gc;
2071 
2072   do {
2073     retry_gc = false;
2074 
2075     {
2076       MutexLocker ml(Heap_lock);
2077 
2078       // Read the GC count while holding the Heap_lock
2079       gc_count_before = total_collections();
2080       full_gc_count_before = total_full_collections();
2081       old_marking_count_before = _old_marking_cycles_started;
2082     }
2083 
2084     if (should_do_concurrent_full_gc(cause)) {
2085       // Schedule an initial-mark evacuation pause that will start a
2086       // concurrent cycle. We're setting word_size to 0 which means that
2087       // we are not requesting a post-GC allocation.
2088       VM_G1CollectForAllocation op(0,     /* word_size */
2089                                    gc_count_before,
2090                                    cause,
2091                                    true,  /* should_initiate_conc_mark */
2092                                    g1_policy()->max_pause_time_ms());
2093       VMThread::execute(&op);
2094       if (!op.pause_succeeded()) {
2095         if (old_marking_count_before == _old_marking_cycles_started) {
2096           retry_gc = op.should_retry_gc();
2097         } else {
2098           // A Full GC happened while we were trying to schedule the
2099           // initial-mark GC. No point in starting a new cycle given
2100           // that the whole heap was collected anyway.
2101         }
2102 
2103         if (retry_gc) {
2104           if (GCLocker::is_active_and_needs_gc()) {
2105             GCLocker::stall_until_clear();
2106           }
2107         }
2108       }
2109     } else {
2110       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2111           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2112 
2113         // Schedule a standard evacuation pause. We're setting word_size
2114         // to 0 which means that we are not requesting a post-GC allocation.
2115         VM_G1CollectForAllocation op(0,     /* word_size */
2116                                      gc_count_before,
2117                                      cause,
2118                                      false, /* should_initiate_conc_mark */
2119                                      g1_policy()->max_pause_time_ms());
2120         VMThread::execute(&op);
2121       } else {
2122         // Schedule a Full GC.
2123         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2124         VMThread::execute(&op);
2125       }
2126     }
2127   } while (retry_gc);
2128 }
2129 
2130 bool G1CollectedHeap::is_in(const void* p) const {
2131   if (_hrm.reserved().contains(p)) {
2132     // Given that we know that p is in the reserved space,
2133     // heap_region_containing() should successfully
2134     // return the containing region.
2135     HeapRegion* hr = heap_region_containing(p);
2136     return hr->is_in(p);
2137   } else {
2138     return false;
2139   }
2140 }
2141 
2142 #ifdef ASSERT
2143 bool G1CollectedHeap::is_in_exact(const void* p) const {
2144   bool contains = reserved_region().contains(p);
2145   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2146   if (contains && available) {
2147     return true;
2148   } else {
2149     return false;
2150   }
2151 }
2152 #endif
2153 
2154 // Iteration functions.
2155 
2156 // Iterates an ObjectClosure over all objects within a HeapRegion.
2157 
2158 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2159   ObjectClosure* _cl;
2160 public:
2161   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2162   bool do_heap_region(HeapRegion* r) {
2163     if (!r->is_continues_humongous()) {
2164       r->object_iterate(_cl);
2165     }
2166     return false;
2167   }
2168 };
2169 
2170 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2171   IterateObjectClosureRegionClosure blk(cl);
2172   heap_region_iterate(&blk);
2173 }
2174 
2175 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2176   _hrm.iterate(cl);
2177 }
2178 
2179 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2180                                                                  HeapRegionClaimer *hrclaimer,
2181                                                                  uint worker_id) const {
2182   _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2183 }
2184 
2185 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2186                                                          HeapRegionClaimer *hrclaimer) const {
2187   _hrm.par_iterate(cl, hrclaimer, 0);
2188 }
2189 
2190 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2191   _collection_set.iterate(cl);
2192 }
2193 
2194 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2195   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2196 }
2197 
2198 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2199   HeapRegion* hr = heap_region_containing(addr);
2200   return hr->block_start(addr);
2201 }
2202 
2203 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2204   HeapRegion* hr = heap_region_containing(addr);
2205   return hr->block_size(addr);
2206 }
2207 
2208 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2209   HeapRegion* hr = heap_region_containing(addr);
2210   return hr->block_is_obj(addr);
2211 }
2212 
2213 bool G1CollectedHeap::supports_tlab_allocation() const {
2214   return true;
2215 }
2216 
2217 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2218   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2219 }
2220 
2221 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2222   return _eden.length() * HeapRegion::GrainBytes;
2223 }
2224 
2225 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2226 // must be equal to the humongous object limit.
2227 size_t G1CollectedHeap::max_tlab_size() const {
2228   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2229 }
2230 
2231 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2232   return _allocator->unsafe_max_tlab_alloc();
2233 }
2234 
2235 size_t G1CollectedHeap::max_capacity() const {
2236   return _hrm.reserved().byte_size();
2237 }
2238 
2239 jlong G1CollectedHeap::millis_since_last_gc() {
2240   // See the notes in GenCollectedHeap::millis_since_last_gc()
2241   // for more information about the implementation.
2242   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2243     _g1_policy->collection_pause_end_millis();
2244   if (ret_val < 0) {
2245     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2246       ". returning zero instead.", ret_val);
2247     return 0;
2248   }
2249   return ret_val;
2250 }
2251 
2252 void G1CollectedHeap::deduplicate_string(oop str) {
2253   assert(java_lang_String::is_instance(str), "invariant");
2254 
2255   if (G1StringDedup::is_enabled()) {
2256     G1StringDedup::deduplicate(str);
2257   }
2258 }
2259 
2260 void G1CollectedHeap::prepare_for_verify() {
2261   _verifier->prepare_for_verify();
2262 }
2263 
2264 void G1CollectedHeap::verify(VerifyOption vo) {
2265   _verifier->verify(vo);
2266 }
2267 
2268 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2269   return true;
2270 }
2271 
2272 const char* const* G1CollectedHeap::concurrent_phases() const {
2273   return _cm_thread->concurrent_phases();
2274 }
2275 
2276 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2277   return _cm_thread->request_concurrent_phase(phase);
2278 }
2279 
2280 class PrintRegionClosure: public HeapRegionClosure {
2281   outputStream* _st;
2282 public:
2283   PrintRegionClosure(outputStream* st) : _st(st) {}
2284   bool do_heap_region(HeapRegion* r) {
2285     r->print_on(_st);
2286     return false;
2287   }
2288 };
2289 
2290 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2291                                        const HeapRegion* hr,
2292                                        const VerifyOption vo) const {
2293   switch (vo) {
2294   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2295   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2296   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2297   default:                            ShouldNotReachHere();
2298   }
2299   return false; // keep some compilers happy
2300 }
2301 
2302 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2303                                        const VerifyOption vo) const {
2304   switch (vo) {
2305   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2306   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2307   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2308   default:                            ShouldNotReachHere();
2309   }
2310   return false; // keep some compilers happy
2311 }
2312 
2313 void G1CollectedHeap::print_heap_regions() const {
2314   LogTarget(Trace, gc, heap, region) lt;
2315   if (lt.is_enabled()) {
2316     LogStream ls(lt);
2317     print_regions_on(&ls);
2318   }
2319 }
2320 
2321 void G1CollectedHeap::print_on(outputStream* st) const {
2322   st->print(" %-20s", "garbage-first heap");
2323   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2324             capacity()/K, used_unlocked()/K);
2325   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2326             p2i(_hrm.reserved().start()),
2327             p2i(_hrm.reserved().end()));
2328   st->cr();
2329   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2330   uint young_regions = young_regions_count();
2331   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2332             (size_t) young_regions * HeapRegion::GrainBytes / K);
2333   uint survivor_regions = survivor_regions_count();
2334   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2335             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2336   st->cr();
2337   MetaspaceUtils::print_on(st);
2338 }
2339 
2340 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2341   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2342                "HS=humongous(starts), HC=humongous(continues), "
2343                "CS=collection set, F=free, A=archive, "
2344                "TAMS=top-at-mark-start (previous, next)");
2345   PrintRegionClosure blk(st);
2346   heap_region_iterate(&blk);
2347 }
2348 
2349 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2350   print_on(st);
2351 
2352   // Print the per-region information.
2353   print_regions_on(st);
2354 }
2355 
2356 void G1CollectedHeap::print_on_error(outputStream* st) const {
2357   this->CollectedHeap::print_on_error(st);
2358 
2359   if (_cm != NULL) {
2360     st->cr();
2361     _cm->print_on_error(st);
2362   }
2363 }
2364 
2365 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2366   workers()->print_worker_threads_on(st);
2367   _cm_thread->print_on(st);
2368   st->cr();
2369   _cm->print_worker_threads_on(st);
2370   _cr->print_threads_on(st);
2371   _young_gen_sampling_thread->print_on(st);
2372   if (G1StringDedup::is_enabled()) {
2373     G1StringDedup::print_worker_threads_on(st);
2374   }
2375 }
2376 
2377 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2378   workers()->threads_do(tc);
2379   tc->do_thread(_cm_thread);
2380   _cm->threads_do(tc);
2381   _cr->threads_do(tc);
2382   tc->do_thread(_young_gen_sampling_thread);
2383   if (G1StringDedup::is_enabled()) {
2384     G1StringDedup::threads_do(tc);
2385   }
2386 }
2387 
2388 void G1CollectedHeap::print_tracing_info() const {
2389   g1_rem_set()->print_summary_info();
2390   concurrent_mark()->print_summary_info();
2391 }
2392 
2393 #ifndef PRODUCT
2394 // Helpful for debugging RSet issues.
2395 
2396 class PrintRSetsClosure : public HeapRegionClosure {
2397 private:
2398   const char* _msg;
2399   size_t _occupied_sum;
2400 
2401 public:
2402   bool do_heap_region(HeapRegion* r) {
2403     HeapRegionRemSet* hrrs = r->rem_set();
2404     size_t occupied = hrrs->occupied();
2405     _occupied_sum += occupied;
2406 
2407     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2408     if (occupied == 0) {
2409       tty->print_cr("  RSet is empty");
2410     } else {
2411       hrrs->print();
2412     }
2413     tty->print_cr("----------");
2414     return false;
2415   }
2416 
2417   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2418     tty->cr();
2419     tty->print_cr("========================================");
2420     tty->print_cr("%s", msg);
2421     tty->cr();
2422   }
2423 
2424   ~PrintRSetsClosure() {
2425     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2426     tty->print_cr("========================================");
2427     tty->cr();
2428   }
2429 };
2430 
2431 void G1CollectedHeap::print_cset_rsets() {
2432   PrintRSetsClosure cl("Printing CSet RSets");
2433   collection_set_iterate(&cl);
2434 }
2435 
2436 void G1CollectedHeap::print_all_rsets() {
2437   PrintRSetsClosure cl("Printing All RSets");;
2438   heap_region_iterate(&cl);
2439 }
2440 #endif // PRODUCT
2441 
2442 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2443 
2444   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2445   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2446   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2447 
2448   size_t eden_capacity_bytes =
2449     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2450 
2451   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2452   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2453                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2454 }
2455 
2456 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2457   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2458                        stats->unused(), stats->used(), stats->region_end_waste(),
2459                        stats->regions_filled(), stats->direct_allocated(),
2460                        stats->failure_used(), stats->failure_waste());
2461 }
2462 
2463 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2464   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2465   gc_tracer->report_gc_heap_summary(when, heap_summary);
2466 
2467   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2468   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2469 }
2470 
2471 G1CollectedHeap* G1CollectedHeap::heap() {
2472   CollectedHeap* heap = Universe::heap();
2473   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2474   assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2475   return (G1CollectedHeap*)heap;
2476 }
2477 
2478 void G1CollectedHeap::gc_prologue(bool full) {
2479   // always_do_update_barrier = false;
2480   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2481 
2482   // This summary needs to be printed before incrementing total collections.
2483   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2484 
2485   // Update common counters.
2486   increment_total_collections(full /* full gc */);
2487   if (full) {
2488     increment_old_marking_cycles_started();
2489   }
2490 
2491   // Fill TLAB's and such
2492   double start = os::elapsedTime();
2493   ensure_parsability(true);
2494   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2495 }
2496 
2497 void G1CollectedHeap::gc_epilogue(bool full) {
2498   // Update common counters.
2499   if (full) {
2500     // Update the number of full collections that have been completed.
2501     increment_old_marking_cycles_completed(false /* concurrent */);
2502   }
2503 
2504   // We are at the end of the GC. Total collections has already been increased.
2505   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2506 
2507   // FIXME: what is this about?
2508   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2509   // is set.
2510 #if COMPILER2_OR_JVMCI
2511   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2512 #endif
2513   // always_do_update_barrier = true;
2514 
2515   double start = os::elapsedTime();
2516   resize_all_tlabs();
2517   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2518 
2519   MemoryService::track_memory_usage();
2520   // We have just completed a GC. Update the soft reference
2521   // policy with the new heap occupancy
2522   Universe::update_heap_info_at_gc();
2523 }
2524 
2525 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2526                                                uint gc_count_before,
2527                                                bool* succeeded,
2528                                                GCCause::Cause gc_cause) {
2529   assert_heap_not_locked_and_not_at_safepoint();
2530   VM_G1CollectForAllocation op(word_size,
2531                                gc_count_before,
2532                                gc_cause,
2533                                false, /* should_initiate_conc_mark */
2534                                g1_policy()->max_pause_time_ms());
2535   VMThread::execute(&op);
2536 
2537   HeapWord* result = op.result();
2538   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2539   assert(result == NULL || ret_succeeded,
2540          "the result should be NULL if the VM did not succeed");
2541   *succeeded = ret_succeeded;
2542 
2543   assert_heap_not_locked();
2544   return result;
2545 }
2546 
2547 void G1CollectedHeap::do_concurrent_mark() {
2548   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2549   if (!_cm_thread->in_progress()) {
2550     _cm_thread->set_started();
2551     CGC_lock->notify();
2552   }
2553 }
2554 
2555 size_t G1CollectedHeap::pending_card_num() {
2556   size_t extra_cards = 0;
2557   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2558     DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2559     extra_cards += dcq.size();
2560   }
2561   DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2562   size_t buffer_size = dcqs.buffer_size();
2563   size_t buffer_num = dcqs.completed_buffers_num();
2564 
2565   return buffer_size * buffer_num + extra_cards;
2566 }
2567 
2568 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2569   // We don't nominate objects with many remembered set entries, on
2570   // the assumption that such objects are likely still live.
2571   HeapRegionRemSet* rem_set = r->rem_set();
2572 
2573   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2574          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2575          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2576 }
2577 
2578 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2579  private:
2580   size_t _total_humongous;
2581   size_t _candidate_humongous;
2582 
2583   DirtyCardQueue _dcq;
2584 
2585   bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2586     assert(region->is_starts_humongous(), "Must start a humongous object");
2587 
2588     oop obj = oop(region->bottom());
2589 
2590     // Dead objects cannot be eager reclaim candidates. Due to class
2591     // unloading it is unsafe to query their classes so we return early.
2592     if (g1h->is_obj_dead(obj, region)) {
2593       return false;
2594     }
2595 
2596     // If we do not have a complete remembered set for the region, then we can
2597     // not be sure that we have all references to it.
2598     if (!region->rem_set()->is_complete()) {
2599       return false;
2600     }
2601     // Candidate selection must satisfy the following constraints
2602     // while concurrent marking is in progress:
2603     //
2604     // * In order to maintain SATB invariants, an object must not be
2605     // reclaimed if it was allocated before the start of marking and
2606     // has not had its references scanned.  Such an object must have
2607     // its references (including type metadata) scanned to ensure no
2608     // live objects are missed by the marking process.  Objects
2609     // allocated after the start of concurrent marking don't need to
2610     // be scanned.
2611     //
2612     // * An object must not be reclaimed if it is on the concurrent
2613     // mark stack.  Objects allocated after the start of concurrent
2614     // marking are never pushed on the mark stack.
2615     //
2616     // Nominating only objects allocated after the start of concurrent
2617     // marking is sufficient to meet both constraints.  This may miss
2618     // some objects that satisfy the constraints, but the marking data
2619     // structures don't support efficiently performing the needed
2620     // additional tests or scrubbing of the mark stack.
2621     //
2622     // However, we presently only nominate is_typeArray() objects.
2623     // A humongous object containing references induces remembered
2624     // set entries on other regions.  In order to reclaim such an
2625     // object, those remembered sets would need to be cleaned up.
2626     //
2627     // We also treat is_typeArray() objects specially, allowing them
2628     // to be reclaimed even if allocated before the start of
2629     // concurrent mark.  For this we rely on mark stack insertion to
2630     // exclude is_typeArray() objects, preventing reclaiming an object
2631     // that is in the mark stack.  We also rely on the metadata for
2632     // such objects to be built-in and so ensured to be kept live.
2633     // Frequent allocation and drop of large binary blobs is an
2634     // important use case for eager reclaim, and this special handling
2635     // may reduce needed headroom.
2636 
2637     return obj->is_typeArray() &&
2638            g1h->is_potential_eager_reclaim_candidate(region);
2639   }
2640 
2641  public:
2642   RegisterHumongousWithInCSetFastTestClosure()
2643   : _total_humongous(0),
2644     _candidate_humongous(0),
2645     _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2646   }
2647 
2648   virtual bool do_heap_region(HeapRegion* r) {
2649     if (!r->is_starts_humongous()) {
2650       return false;
2651     }
2652     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2653 
2654     bool is_candidate = humongous_region_is_candidate(g1h, r);
2655     uint rindex = r->hrm_index();
2656     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2657     if (is_candidate) {
2658       _candidate_humongous++;
2659       g1h->register_humongous_region_with_cset(rindex);
2660       // Is_candidate already filters out humongous object with large remembered sets.
2661       // If we have a humongous object with a few remembered sets, we simply flush these
2662       // remembered set entries into the DCQS. That will result in automatic
2663       // re-evaluation of their remembered set entries during the following evacuation
2664       // phase.
2665       if (!r->rem_set()->is_empty()) {
2666         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2667                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2668         G1CardTable* ct = g1h->card_table();
2669         HeapRegionRemSetIterator hrrs(r->rem_set());
2670         size_t card_index;
2671         while (hrrs.has_next(card_index)) {
2672           jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2673           // The remembered set might contain references to already freed
2674           // regions. Filter out such entries to avoid failing card table
2675           // verification.
2676           if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2677             if (*card_ptr != G1CardTable::dirty_card_val()) {
2678               *card_ptr = G1CardTable::dirty_card_val();
2679               _dcq.enqueue(card_ptr);
2680             }
2681           }
2682         }
2683         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2684                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2685                hrrs.n_yielded(), r->rem_set()->occupied());
2686         // We should only clear the card based remembered set here as we will not
2687         // implicitly rebuild anything else during eager reclaim. Note that at the moment
2688         // (and probably never) we do not enter this path if there are other kind of
2689         // remembered sets for this region.
2690         r->rem_set()->clear_locked(true /* only_cardset */);
2691         // Clear_locked() above sets the state to Empty. However we want to continue
2692         // collecting remembered set entries for humongous regions that were not
2693         // reclaimed.
2694         r->rem_set()->set_state_complete();
2695       }
2696       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2697     }
2698     _total_humongous++;
2699 
2700     return false;
2701   }
2702 
2703   size_t total_humongous() const { return _total_humongous; }
2704   size_t candidate_humongous() const { return _candidate_humongous; }
2705 
2706   void flush_rem_set_entries() { _dcq.flush(); }
2707 };
2708 
2709 void G1CollectedHeap::register_humongous_regions_with_cset() {
2710   if (!G1EagerReclaimHumongousObjects) {
2711     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2712     return;
2713   }
2714   double time = os::elapsed_counter();
2715 
2716   // Collect reclaim candidate information and register candidates with cset.
2717   RegisterHumongousWithInCSetFastTestClosure cl;
2718   heap_region_iterate(&cl);
2719 
2720   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2721   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2722                                                                   cl.total_humongous(),
2723                                                                   cl.candidate_humongous());
2724   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2725 
2726   // Finally flush all remembered set entries to re-check into the global DCQS.
2727   cl.flush_rem_set_entries();
2728 }
2729 
2730 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2731   public:
2732     bool do_heap_region(HeapRegion* hr) {
2733       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2734         hr->verify_rem_set();
2735       }
2736       return false;
2737     }
2738 };
2739 
2740 uint G1CollectedHeap::num_task_queues() const {
2741   return _task_queues->size();
2742 }
2743 
2744 #if TASKQUEUE_STATS
2745 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2746   st->print_raw_cr("GC Task Stats");
2747   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2748   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2749 }
2750 
2751 void G1CollectedHeap::print_taskqueue_stats() const {
2752   if (!log_is_enabled(Trace, gc, task, stats)) {
2753     return;
2754   }
2755   Log(gc, task, stats) log;
2756   ResourceMark rm;
2757   LogStream ls(log.trace());
2758   outputStream* st = &ls;
2759 
2760   print_taskqueue_stats_hdr(st);
2761 
2762   TaskQueueStats totals;
2763   const uint n = num_task_queues();
2764   for (uint i = 0; i < n; ++i) {
2765     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2766     totals += task_queue(i)->stats;
2767   }
2768   st->print_raw("tot "); totals.print(st); st->cr();
2769 
2770   DEBUG_ONLY(totals.verify());
2771 }
2772 
2773 void G1CollectedHeap::reset_taskqueue_stats() {
2774   const uint n = num_task_queues();
2775   for (uint i = 0; i < n; ++i) {
2776     task_queue(i)->stats.reset();
2777   }
2778 }
2779 #endif // TASKQUEUE_STATS
2780 
2781 void G1CollectedHeap::wait_for_root_region_scanning() {
2782   double scan_wait_start = os::elapsedTime();
2783   // We have to wait until the CM threads finish scanning the
2784   // root regions as it's the only way to ensure that all the
2785   // objects on them have been correctly scanned before we start
2786   // moving them during the GC.
2787   bool waited = _cm->root_regions()->wait_until_scan_finished();
2788   double wait_time_ms = 0.0;
2789   if (waited) {
2790     double scan_wait_end = os::elapsedTime();
2791     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2792   }
2793   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2794 }
2795 
2796 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2797 private:
2798   G1HRPrinter* _hr_printer;
2799 public:
2800   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2801 
2802   virtual bool do_heap_region(HeapRegion* r) {
2803     _hr_printer->cset(r);
2804     return false;
2805   }
2806 };
2807 
2808 void G1CollectedHeap::start_new_collection_set() {
2809   collection_set()->start_incremental_building();
2810 
2811   clear_cset_fast_test();
2812 
2813   guarantee(_eden.length() == 0, "eden should have been cleared");
2814   g1_policy()->transfer_survivors_to_cset(survivor());
2815 }
2816 
2817 bool
2818 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2819   assert_at_safepoint_on_vm_thread();
2820   guarantee(!is_gc_active(), "collection is not reentrant");
2821 
2822   if (GCLocker::check_active_before_gc()) {
2823     return false;
2824   }
2825 
2826   _gc_timer_stw->register_gc_start();
2827 
2828   GCIdMark gc_id_mark;
2829   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2830 
2831   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2832   ResourceMark rm;
2833 
2834   g1_policy()->note_gc_start();
2835 
2836   wait_for_root_region_scanning();
2837 
2838   print_heap_before_gc();
2839   print_heap_regions();
2840   trace_heap_before_gc(_gc_tracer_stw);
2841 
2842   _verifier->verify_region_sets_optional();
2843   _verifier->verify_dirty_young_regions();
2844 
2845   // We should not be doing initial mark unless the conc mark thread is running
2846   if (!_cm_thread->should_terminate()) {
2847     // This call will decide whether this pause is an initial-mark
2848     // pause. If it is, in_initial_mark_gc() will return true
2849     // for the duration of this pause.
2850     g1_policy()->decide_on_conc_mark_initiation();
2851   }
2852 
2853   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2854   assert(!collector_state()->in_initial_mark_gc() ||
2855           collector_state()->in_young_only_phase(), "sanity");
2856 
2857   // We also do not allow mixed GCs during marking.
2858   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2859 
2860   // Record whether this pause is an initial mark. When the current
2861   // thread has completed its logging output and it's safe to signal
2862   // the CM thread, the flag's value in the policy has been reset.
2863   bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2864 
2865   // Inner scope for scope based logging, timers, and stats collection
2866   {
2867     EvacuationInfo evacuation_info;
2868 
2869     if (collector_state()->in_initial_mark_gc()) {
2870       // We are about to start a marking cycle, so we increment the
2871       // full collection counter.
2872       increment_old_marking_cycles_started();
2873       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2874     }
2875 
2876     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2877 
2878     GCTraceCPUTime tcpu;
2879 
2880     G1HeapVerifier::G1VerifyType verify_type;
2881     FormatBuffer<> gc_string("Pause Young ");
2882     if (collector_state()->in_initial_mark_gc()) {
2883       gc_string.append("(Concurrent Start)");
2884       verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2885     } else if (collector_state()->in_young_only_phase()) {
2886       if (collector_state()->in_young_gc_before_mixed()) {
2887         gc_string.append("(Prepare Mixed)");
2888       } else {
2889         gc_string.append("(Normal)");
2890       }
2891       verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2892     } else {
2893       gc_string.append("(Mixed)");
2894       verify_type = G1HeapVerifier::G1VerifyMixed;
2895     }
2896     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2897 
2898     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2899                                                                   workers()->active_workers(),
2900                                                                   Threads::number_of_non_daemon_threads());
2901     active_workers = workers()->update_active_workers(active_workers);
2902     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2903 
2904     G1MonitoringScope ms(g1mm(),
2905                          false /* full_gc */,
2906                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2907 
2908     G1HeapTransition heap_transition(this);
2909     size_t heap_used_bytes_before_gc = used();
2910 
2911     // Don't dynamically change the number of GC threads this early.  A value of
2912     // 0 is used to indicate serial work.  When parallel work is done,
2913     // it will be set.
2914 
2915     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2916       IsGCActiveMark x;
2917 
2918       gc_prologue(false);
2919 
2920       if (VerifyRememberedSets) {
2921         log_info(gc, verify)("[Verifying RemSets before GC]");
2922         VerifyRegionRemSetClosure v_cl;
2923         heap_region_iterate(&v_cl);
2924       }
2925 
2926       _verifier->verify_before_gc(verify_type);
2927 
2928       _verifier->check_bitmaps("GC Start");
2929 
2930 #if COMPILER2_OR_JVMCI
2931       DerivedPointerTable::clear();
2932 #endif
2933 
2934       // Please see comment in g1CollectedHeap.hpp and
2935       // G1CollectedHeap::ref_processing_init() to see how
2936       // reference processing currently works in G1.
2937 
2938       // Enable discovery in the STW reference processor
2939       _ref_processor_stw->enable_discovery();
2940 
2941       {
2942         // We want to temporarily turn off discovery by the
2943         // CM ref processor, if necessary, and turn it back on
2944         // on again later if we do. Using a scoped
2945         // NoRefDiscovery object will do this.
2946         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2947 
2948         // Forget the current alloc region (we might even choose it to be part
2949         // of the collection set!).
2950         _allocator->release_mutator_alloc_region();
2951 
2952         // This timing is only used by the ergonomics to handle our pause target.
2953         // It is unclear why this should not include the full pause. We will
2954         // investigate this in CR 7178365.
2955         //
2956         // Preserving the old comment here if that helps the investigation:
2957         //
2958         // The elapsed time induced by the start time below deliberately elides
2959         // the possible verification above.
2960         double sample_start_time_sec = os::elapsedTime();
2961 
2962         g1_policy()->record_collection_pause_start(sample_start_time_sec);
2963 
2964         if (collector_state()->in_initial_mark_gc()) {
2965           concurrent_mark()->pre_initial_mark();
2966         }
2967 
2968         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2969 
2970         evacuation_info.set_collectionset_regions(collection_set()->region_length());
2971 
2972         // Make sure the remembered sets are up to date. This needs to be
2973         // done before register_humongous_regions_with_cset(), because the
2974         // remembered sets are used there to choose eager reclaim candidates.
2975         // If the remembered sets are not up to date we might miss some
2976         // entries that need to be handled.
2977         g1_rem_set()->cleanupHRRS();
2978 
2979         register_humongous_regions_with_cset();
2980 
2981         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2982 
2983         // We call this after finalize_cset() to
2984         // ensure that the CSet has been finalized.
2985         _cm->verify_no_cset_oops();
2986 
2987         if (_hr_printer.is_active()) {
2988           G1PrintCollectionSetClosure cl(&_hr_printer);
2989           _collection_set.iterate(&cl);
2990         }
2991 
2992         // Initialize the GC alloc regions.
2993         _allocator->init_gc_alloc_regions(evacuation_info);
2994 
2995         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2996         pre_evacuate_collection_set();
2997 
2998         // Actually do the work...
2999         evacuate_collection_set(&per_thread_states);
3000 
3001         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3002 
3003         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3004         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3005 
3006         eagerly_reclaim_humongous_regions();
3007 
3008         record_obj_copy_mem_stats();
3009         _survivor_evac_stats.adjust_desired_plab_sz();
3010         _old_evac_stats.adjust_desired_plab_sz();
3011 
3012         double start = os::elapsedTime();
3013         start_new_collection_set();
3014         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3015 
3016         if (evacuation_failed()) {
3017           double recalculate_used_start = os::elapsedTime();
3018           set_used(recalculate_used());
3019           g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3020 
3021           if (_archive_allocator != NULL) {
3022             _archive_allocator->clear_used();
3023           }
3024           for (uint i = 0; i < ParallelGCThreads; i++) {
3025             if (_evacuation_failed_info_array[i].has_failed()) {
3026               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3027             }
3028           }
3029         } else {
3030           // The "used" of the the collection set have already been subtracted
3031           // when they were freed.  Add in the bytes evacuated.
3032           increase_used(g1_policy()->bytes_copied_during_gc());
3033         }
3034 
3035         if (collector_state()->in_initial_mark_gc()) {
3036           // We have to do this before we notify the CM threads that
3037           // they can start working to make sure that all the
3038           // appropriate initialization is done on the CM object.
3039           concurrent_mark()->post_initial_mark();
3040           // Note that we don't actually trigger the CM thread at
3041           // this point. We do that later when we're sure that
3042           // the current thread has completed its logging output.
3043         }
3044 
3045         allocate_dummy_regions();
3046 
3047         _allocator->init_mutator_alloc_region();
3048 
3049         {
3050           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3051           if (expand_bytes > 0) {
3052             size_t bytes_before = capacity();
3053             // No need for an ergo logging here,
3054             // expansion_amount() does this when it returns a value > 0.
3055             double expand_ms;
3056             if (!expand(expand_bytes, _workers, &expand_ms)) {
3057               // We failed to expand the heap. Cannot do anything about it.
3058             }
3059             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3060           }
3061         }
3062 
3063         // We redo the verification but now wrt to the new CSet which
3064         // has just got initialized after the previous CSet was freed.
3065         _cm->verify_no_cset_oops();
3066 
3067         // This timing is only used by the ergonomics to handle our pause target.
3068         // It is unclear why this should not include the full pause. We will
3069         // investigate this in CR 7178365.
3070         double sample_end_time_sec = os::elapsedTime();
3071         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3072         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3073         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3074 
3075         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3076         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3077 
3078         if (VerifyRememberedSets) {
3079           log_info(gc, verify)("[Verifying RemSets after GC]");
3080           VerifyRegionRemSetClosure v_cl;
3081           heap_region_iterate(&v_cl);
3082         }
3083 
3084         _verifier->verify_after_gc(verify_type);
3085         _verifier->check_bitmaps("GC End");
3086 
3087         assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3088         _ref_processor_stw->verify_no_references_recorded();
3089 
3090         // CM reference discovery will be re-enabled if necessary.
3091       }
3092 
3093 #ifdef TRACESPINNING
3094       ParallelTaskTerminator::print_termination_counts();
3095 #endif
3096 
3097       gc_epilogue(false);
3098     }
3099 
3100     // Print the remainder of the GC log output.
3101     if (evacuation_failed()) {
3102       log_info(gc)("To-space exhausted");
3103     }
3104 
3105     g1_policy()->print_phases();
3106     heap_transition.print();
3107 
3108     // It is not yet to safe to tell the concurrent mark to
3109     // start as we have some optional output below. We don't want the
3110     // output from the concurrent mark thread interfering with this
3111     // logging output either.
3112 
3113     _hrm.verify_optional();
3114     _verifier->verify_region_sets_optional();
3115 
3116     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3117     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3118 
3119     print_heap_after_gc();
3120     print_heap_regions();
3121     trace_heap_after_gc(_gc_tracer_stw);
3122 
3123     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3124     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3125     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3126     // before any GC notifications are raised.
3127     g1mm()->update_sizes();
3128 
3129     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3130     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3131     _gc_timer_stw->register_gc_end();
3132     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3133   }
3134   // It should now be safe to tell the concurrent mark thread to start
3135   // without its logging output interfering with the logging output
3136   // that came from the pause.
3137 
3138   if (should_start_conc_mark) {
3139     // CAUTION: after the doConcurrentMark() call below,
3140     // the concurrent marking thread(s) could be running
3141     // concurrently with us. Make sure that anything after
3142     // this point does not assume that we are the only GC thread
3143     // running. Note: of course, the actual marking work will
3144     // not start until the safepoint itself is released in
3145     // SuspendibleThreadSet::desynchronize().
3146     do_concurrent_mark();
3147   }
3148 
3149   return true;
3150 }
3151 
3152 void G1CollectedHeap::remove_self_forwarding_pointers() {
3153   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3154   workers()->run_task(&rsfp_task);
3155 }
3156 
3157 void G1CollectedHeap::restore_after_evac_failure() {
3158   double remove_self_forwards_start = os::elapsedTime();
3159 
3160   remove_self_forwarding_pointers();
3161   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3162   _preserved_marks_set.restore(&task_executor);
3163 
3164   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3165 }
3166 
3167 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3168   if (!_evacuation_failed) {
3169     _evacuation_failed = true;
3170   }
3171 
3172   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3173   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3174 }
3175 
3176 bool G1ParEvacuateFollowersClosure::offer_termination() {
3177   EventGCPhaseParallel event;
3178   G1ParScanThreadState* const pss = par_scan_state();
3179   start_term_time();
3180   const bool res = terminator()->offer_termination();
3181   end_term_time();
3182   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3183   return res;
3184 }
3185 
3186 void G1ParEvacuateFollowersClosure::do_void() {
3187   EventGCPhaseParallel event;
3188   G1ParScanThreadState* const pss = par_scan_state();
3189   pss->trim_queue();
3190   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3191   do {
3192     EventGCPhaseParallel event;
3193     pss->steal_and_trim_queue(queues());
3194     event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3195   } while (!offer_termination());
3196 }
3197 
3198 class G1ParTask : public AbstractGangTask {
3199 protected:
3200   G1CollectedHeap*         _g1h;
3201   G1ParScanThreadStateSet* _pss;
3202   RefToScanQueueSet*       _queues;
3203   G1RootProcessor*         _root_processor;
3204   ParallelTaskTerminator   _terminator;
3205   uint                     _n_workers;
3206 
3207 public:
3208   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3209     : AbstractGangTask("G1 collection"),
3210       _g1h(g1h),
3211       _pss(per_thread_states),
3212       _queues(task_queues),
3213       _root_processor(root_processor),
3214       _terminator(n_workers, _queues),
3215       _n_workers(n_workers)
3216   {}
3217 
3218   void work(uint worker_id) {
3219     if (worker_id >= _n_workers) return;  // no work needed this round
3220 
3221     double start_sec = os::elapsedTime();
3222     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3223 
3224     {
3225       ResourceMark rm;
3226       HandleMark   hm;
3227 
3228       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3229 
3230       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3231       pss->set_ref_discoverer(rp);
3232 
3233       double start_strong_roots_sec = os::elapsedTime();
3234 
3235       _root_processor->evacuate_roots(pss, worker_id);
3236 
3237       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3238       // treating the nmethods visited to act as roots for concurrent marking.
3239       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3240       // objects copied by the current evacuation.
3241       _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3242 
3243       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3244 
3245       double term_sec = 0.0;
3246       size_t evac_term_attempts = 0;
3247       {
3248         double start = os::elapsedTime();
3249         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3250         evac.do_void();
3251 
3252         evac_term_attempts = evac.term_attempts();
3253         term_sec = evac.term_time();
3254         double elapsed_sec = os::elapsedTime() - start;
3255 
3256         G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3257         p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3258         p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3259         p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3260       }
3261 
3262       assert(pss->queue_is_empty(), "should be empty");
3263 
3264       if (log_is_enabled(Debug, gc, task, stats)) {
3265         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3266         size_t lab_waste;
3267         size_t lab_undo_waste;
3268         pss->waste(lab_waste, lab_undo_waste);
3269         _g1h->print_termination_stats(worker_id,
3270                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3271                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3272                                       term_sec * 1000.0,                          /* evac term time */
3273                                       evac_term_attempts,                         /* evac term attempts */
3274                                       lab_waste,                                  /* alloc buffer waste */
3275                                       lab_undo_waste                              /* undo waste */
3276                                       );
3277       }
3278 
3279       // Close the inner scope so that the ResourceMark and HandleMark
3280       // destructors are executed here and are included as part of the
3281       // "GC Worker Time".
3282     }
3283     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3284   }
3285 };
3286 
3287 void G1CollectedHeap::print_termination_stats_hdr() {
3288   log_debug(gc, task, stats)("GC Termination Stats");
3289   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3290   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3291   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3292 }
3293 
3294 void G1CollectedHeap::print_termination_stats(uint worker_id,
3295                                               double elapsed_ms,
3296                                               double strong_roots_ms,
3297                                               double term_ms,
3298                                               size_t term_attempts,
3299                                               size_t alloc_buffer_waste,
3300                                               size_t undo_waste) const {
3301   log_debug(gc, task, stats)
3302               ("%3d %9.2f %9.2f %6.2f "
3303                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3304                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3305                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3306                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3307                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3308                alloc_buffer_waste * HeapWordSize / K,
3309                undo_waste * HeapWordSize / K);
3310 }
3311 
3312 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3313                                         bool class_unloading_occurred) {
3314   uint n_workers = workers()->active_workers();
3315 
3316   G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3317   ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred);
3318   workers()->run_task(&g1_unlink_task);
3319 }
3320 
3321 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3322                                        bool process_strings,
3323                                        bool process_string_dedup) {
3324   if (!process_strings && !process_string_dedup) {
3325     // Nothing to clean.
3326     return;
3327   }
3328 
3329   G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3330   StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings);
3331   workers()->run_task(&g1_unlink_task);
3332 }
3333 
3334 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3335  private:
3336   DirtyCardQueueSet* _queue;
3337   G1CollectedHeap* _g1h;
3338  public:
3339   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3340     _queue(queue), _g1h(g1h) { }
3341 
3342   virtual void work(uint worker_id) {
3343     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3344     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3345 
3346     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3347     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3348 
3349     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3350   }
3351 };
3352 
3353 void G1CollectedHeap::redirty_logged_cards() {
3354   double redirty_logged_cards_start = os::elapsedTime();
3355 
3356   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3357   dirty_card_queue_set().reset_for_par_iteration();
3358   workers()->run_task(&redirty_task);
3359 
3360   DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3361   dcq.merge_bufferlists(&dirty_card_queue_set());
3362   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3363 
3364   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3365 }
3366 
3367 // Weak Reference Processing support
3368 
3369 bool G1STWIsAliveClosure::do_object_b(oop p) {
3370   // An object is reachable if it is outside the collection set,
3371   // or is inside and copied.
3372   return !_g1h->is_in_cset(p) || p->is_forwarded();
3373 }
3374 
3375 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3376   assert(obj != NULL, "must not be NULL");
3377   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3378   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3379   // may falsely indicate that this is not the case here: however the collection set only
3380   // contains old regions when concurrent mark is not running.
3381   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3382 }
3383 
3384 // Non Copying Keep Alive closure
3385 class G1KeepAliveClosure: public OopClosure {
3386   G1CollectedHeap*_g1h;
3387 public:
3388   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3389   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3390   void do_oop(oop* p) {
3391     oop obj = *p;
3392     assert(obj != NULL, "the caller should have filtered out NULL values");
3393 
3394     const InCSetState cset_state =_g1h->in_cset_state(obj);
3395     if (!cset_state.is_in_cset_or_humongous()) {
3396       return;
3397     }
3398     if (cset_state.is_in_cset()) {
3399       assert( obj->is_forwarded(), "invariant" );
3400       *p = obj->forwardee();
3401     } else {
3402       assert(!obj->is_forwarded(), "invariant" );
3403       assert(cset_state.is_humongous(),
3404              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3405      _g1h->set_humongous_is_live(obj);
3406     }
3407   }
3408 };
3409 
3410 // Copying Keep Alive closure - can be called from both
3411 // serial and parallel code as long as different worker
3412 // threads utilize different G1ParScanThreadState instances
3413 // and different queues.
3414 
3415 class G1CopyingKeepAliveClosure: public OopClosure {
3416   G1CollectedHeap*         _g1h;
3417   G1ParScanThreadState*    _par_scan_state;
3418 
3419 public:
3420   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3421                             G1ParScanThreadState* pss):
3422     _g1h(g1h),
3423     _par_scan_state(pss)
3424   {}
3425 
3426   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3427   virtual void do_oop(      oop* p) { do_oop_work(p); }
3428 
3429   template <class T> void do_oop_work(T* p) {
3430     oop obj = RawAccess<>::oop_load(p);
3431 
3432     if (_g1h->is_in_cset_or_humongous(obj)) {
3433       // If the referent object has been forwarded (either copied
3434       // to a new location or to itself in the event of an
3435       // evacuation failure) then we need to update the reference
3436       // field and, if both reference and referent are in the G1
3437       // heap, update the RSet for the referent.
3438       //
3439       // If the referent has not been forwarded then we have to keep
3440       // it alive by policy. Therefore we have copy the referent.
3441       //
3442       // When the queue is drained (after each phase of reference processing)
3443       // the object and it's followers will be copied, the reference field set
3444       // to point to the new location, and the RSet updated.
3445       _par_scan_state->push_on_queue(p);
3446     }
3447   }
3448 };
3449 
3450 // Serial drain queue closure. Called as the 'complete_gc'
3451 // closure for each discovered list in some of the
3452 // reference processing phases.
3453 
3454 class G1STWDrainQueueClosure: public VoidClosure {
3455 protected:
3456   G1CollectedHeap* _g1h;
3457   G1ParScanThreadState* _par_scan_state;
3458 
3459   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3460 
3461 public:
3462   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3463     _g1h(g1h),
3464     _par_scan_state(pss)
3465   { }
3466 
3467   void do_void() {
3468     G1ParScanThreadState* const pss = par_scan_state();
3469     pss->trim_queue();
3470   }
3471 };
3472 
3473 // Parallel Reference Processing closures
3474 
3475 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3476 // processing during G1 evacuation pauses.
3477 
3478 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3479 private:
3480   G1CollectedHeap*          _g1h;
3481   G1ParScanThreadStateSet*  _pss;
3482   RefToScanQueueSet*        _queues;
3483   WorkGang*                 _workers;
3484 
3485 public:
3486   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3487                            G1ParScanThreadStateSet* per_thread_states,
3488                            WorkGang* workers,
3489                            RefToScanQueueSet *task_queues) :
3490     _g1h(g1h),
3491     _pss(per_thread_states),
3492     _queues(task_queues),
3493     _workers(workers)
3494   {
3495     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3496   }
3497 
3498   // Executes the given task using concurrent marking worker threads.
3499   virtual void execute(ProcessTask& task, uint ergo_workers);
3500 };
3501 
3502 // Gang task for possibly parallel reference processing
3503 
3504 class G1STWRefProcTaskProxy: public AbstractGangTask {
3505   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3506   ProcessTask&     _proc_task;
3507   G1CollectedHeap* _g1h;
3508   G1ParScanThreadStateSet* _pss;
3509   RefToScanQueueSet* _task_queues;
3510   ParallelTaskTerminator* _terminator;
3511 
3512 public:
3513   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3514                         G1CollectedHeap* g1h,
3515                         G1ParScanThreadStateSet* per_thread_states,
3516                         RefToScanQueueSet *task_queues,
3517                         ParallelTaskTerminator* terminator) :
3518     AbstractGangTask("Process reference objects in parallel"),
3519     _proc_task(proc_task),
3520     _g1h(g1h),
3521     _pss(per_thread_states),
3522     _task_queues(task_queues),
3523     _terminator(terminator)
3524   {}
3525 
3526   virtual void work(uint worker_id) {
3527     // The reference processing task executed by a single worker.
3528     ResourceMark rm;
3529     HandleMark   hm;
3530 
3531     G1STWIsAliveClosure is_alive(_g1h);
3532 
3533     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3534     pss->set_ref_discoverer(NULL);
3535 
3536     // Keep alive closure.
3537     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3538 
3539     // Complete GC closure
3540     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3541 
3542     // Call the reference processing task's work routine.
3543     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3544 
3545     // Note we cannot assert that the refs array is empty here as not all
3546     // of the processing tasks (specifically phase2 - pp2_work) execute
3547     // the complete_gc closure (which ordinarily would drain the queue) so
3548     // the queue may not be empty.
3549   }
3550 };
3551 
3552 // Driver routine for parallel reference processing.
3553 // Creates an instance of the ref processing gang
3554 // task and has the worker threads execute it.
3555 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3556   assert(_workers != NULL, "Need parallel worker threads.");
3557 
3558   assert(_workers->active_workers() >= ergo_workers,
3559          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3560          ergo_workers, _workers->active_workers());
3561   ParallelTaskTerminator terminator(ergo_workers, _queues);
3562   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3563 
3564   _workers->run_task(&proc_task_proxy, ergo_workers);
3565 }
3566 
3567 // End of weak reference support closures
3568 
3569 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3570   double ref_proc_start = os::elapsedTime();
3571 
3572   ReferenceProcessor* rp = _ref_processor_stw;
3573   assert(rp->discovery_enabled(), "should have been enabled");
3574 
3575   // Closure to test whether a referent is alive.
3576   G1STWIsAliveClosure is_alive(this);
3577 
3578   // Even when parallel reference processing is enabled, the processing
3579   // of JNI refs is serial and performed serially by the current thread
3580   // rather than by a worker. The following PSS will be used for processing
3581   // JNI refs.
3582 
3583   // Use only a single queue for this PSS.
3584   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3585   pss->set_ref_discoverer(NULL);
3586   assert(pss->queue_is_empty(), "pre-condition");
3587 
3588   // Keep alive closure.
3589   G1CopyingKeepAliveClosure keep_alive(this, pss);
3590 
3591   // Serial Complete GC closure
3592   G1STWDrainQueueClosure drain_queue(this, pss);
3593 
3594   // Setup the soft refs policy...
3595   rp->setup_policy(false);
3596 
3597   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3598 
3599   ReferenceProcessorStats stats;
3600   if (!rp->processing_is_mt()) {
3601     // Serial reference processing...
3602     stats = rp->process_discovered_references(&is_alive,
3603                                               &keep_alive,
3604                                               &drain_queue,
3605                                               NULL,
3606                                               pt);
3607   } else {
3608     uint no_of_gc_workers = workers()->active_workers();
3609 
3610     // Parallel reference processing
3611     assert(no_of_gc_workers <= rp->max_num_queues(),
3612            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3613            no_of_gc_workers,  rp->max_num_queues());
3614 
3615     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3616     stats = rp->process_discovered_references(&is_alive,
3617                                               &keep_alive,
3618                                               &drain_queue,
3619                                               &par_task_executor,
3620                                               pt);
3621   }
3622 
3623   _gc_tracer_stw->report_gc_reference_stats(stats);
3624 
3625   // We have completed copying any necessary live referent objects.
3626   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3627 
3628   make_pending_list_reachable();
3629 
3630   rp->verify_no_references_recorded();
3631 
3632   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3633   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3634 }
3635 
3636 void G1CollectedHeap::make_pending_list_reachable() {
3637   if (collector_state()->in_initial_mark_gc()) {
3638     oop pll_head = Universe::reference_pending_list();
3639     if (pll_head != NULL) {
3640       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3641       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3642     }
3643   }
3644 }
3645 
3646 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3647   double merge_pss_time_start = os::elapsedTime();
3648   per_thread_states->flush();
3649   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3650 }
3651 
3652 void G1CollectedHeap::pre_evacuate_collection_set() {
3653   _expand_heap_after_alloc_failure = true;
3654   _evacuation_failed = false;
3655 
3656   // Disable the hot card cache.
3657   _hot_card_cache->reset_hot_cache_claimed_index();
3658   _hot_card_cache->set_use_cache(false);
3659 
3660   g1_rem_set()->prepare_for_oops_into_collection_set_do();
3661   _preserved_marks_set.assert_empty();
3662 
3663   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3664 
3665   // InitialMark needs claim bits to keep track of the marked-through CLDs.
3666   if (collector_state()->in_initial_mark_gc()) {
3667     double start_clear_claimed_marks = os::elapsedTime();
3668 
3669     ClassLoaderDataGraph::clear_claimed_marks();
3670 
3671     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3672     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3673   }
3674 }
3675 
3676 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3677   // Should G1EvacuationFailureALot be in effect for this GC?
3678   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3679 
3680   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3681 
3682   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3683 
3684   double start_par_time_sec = os::elapsedTime();
3685   double end_par_time_sec;
3686 
3687   {
3688     const uint n_workers = workers()->active_workers();
3689     G1RootProcessor root_processor(this, n_workers);
3690     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3691 
3692     print_termination_stats_hdr();
3693 
3694     workers()->run_task(&g1_par_task);
3695     end_par_time_sec = os::elapsedTime();
3696 
3697     // Closing the inner scope will execute the destructor
3698     // for the G1RootProcessor object. We record the current
3699     // elapsed time before closing the scope so that time
3700     // taken for the destructor is NOT included in the
3701     // reported parallel time.
3702   }
3703 
3704   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3705   phase_times->record_par_time(par_time_ms);
3706 
3707   double code_root_fixup_time_ms =
3708         (os::elapsedTime() - end_par_time_sec) * 1000.0;
3709   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
3710 }
3711 
3712 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3713   // Also cleans the card table from temporary duplicate detection information used
3714   // during UpdateRS/ScanRS.
3715   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
3716 
3717   // Process any discovered reference objects - we have
3718   // to do this _before_ we retire the GC alloc regions
3719   // as we may have to copy some 'reachable' referent
3720   // objects (and their reachable sub-graphs) that were
3721   // not copied during the pause.
3722   process_discovered_references(per_thread_states);
3723 
3724   // FIXME
3725   // CM's reference processing also cleans up the string table.
3726   // Should we do that here also? We could, but it is a serial operation
3727   // and could significantly increase the pause time.
3728 
3729   G1STWIsAliveClosure is_alive(this);
3730   G1KeepAliveClosure keep_alive(this);
3731 
3732   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3733                               g1_policy()->phase_times()->weak_phase_times());
3734 
3735   if (G1StringDedup::is_enabled()) {
3736     double fixup_start = os::elapsedTime();
3737 
3738     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
3739 
3740     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
3741     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
3742   }
3743 
3744   if (evacuation_failed()) {
3745     restore_after_evac_failure();
3746 
3747     // Reset the G1EvacuationFailureALot counters and flags
3748     // Note: the values are reset only when an actual
3749     // evacuation failure occurs.
3750     NOT_PRODUCT(reset_evacuation_should_fail();)
3751   }
3752 
3753   _preserved_marks_set.assert_empty();
3754 
3755   _allocator->release_gc_alloc_regions(evacuation_info);
3756 
3757   merge_per_thread_state_info(per_thread_states);
3758 
3759   // Reset and re-enable the hot card cache.
3760   // Note the counts for the cards in the regions in the
3761   // collection set are reset when the collection set is freed.
3762   _hot_card_cache->reset_hot_cache();
3763   _hot_card_cache->set_use_cache(true);
3764 
3765   purge_code_root_memory();
3766 
3767   redirty_logged_cards();
3768 #if COMPILER2_OR_JVMCI
3769   double start = os::elapsedTime();
3770   DerivedPointerTable::update_pointers();
3771   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3772 #endif
3773   g1_policy()->print_age_table();
3774 }
3775 
3776 void G1CollectedHeap::record_obj_copy_mem_stats() {
3777   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3778 
3779   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3780                                                create_g1_evac_summary(&_old_evac_stats));
3781 }
3782 
3783 void G1CollectedHeap::free_region(HeapRegion* hr,
3784                                   FreeRegionList* free_list,
3785                                   bool skip_remset,
3786                                   bool skip_hot_card_cache,
3787                                   bool locked) {
3788   assert(!hr->is_free(), "the region should not be free");
3789   assert(!hr->is_empty(), "the region should not be empty");
3790   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
3791   assert(free_list != NULL, "pre-condition");
3792 
3793   if (G1VerifyBitmaps) {
3794     MemRegion mr(hr->bottom(), hr->end());
3795     concurrent_mark()->clear_range_in_prev_bitmap(mr);
3796   }
3797 
3798   // Clear the card counts for this region.
3799   // Note: we only need to do this if the region is not young
3800   // (since we don't refine cards in young regions).
3801   if (!skip_hot_card_cache && !hr->is_young()) {
3802     _hot_card_cache->reset_card_counts(hr);
3803   }
3804   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3805   _g1_policy->remset_tracker()->update_at_free(hr);
3806   free_list->add_ordered(hr);
3807 }
3808 
3809 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3810                                             FreeRegionList* free_list) {
3811   assert(hr->is_humongous(), "this is only for humongous regions");
3812   assert(free_list != NULL, "pre-condition");
3813   hr->clear_humongous();
3814   free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3815 }
3816 
3817 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3818                                            const uint humongous_regions_removed) {
3819   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3820     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3821     _old_set.bulk_remove(old_regions_removed);
3822     _humongous_set.bulk_remove(humongous_regions_removed);
3823   }
3824 
3825 }
3826 
3827 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3828   assert(list != NULL, "list can't be null");
3829   if (!list->is_empty()) {
3830     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3831     _hrm.insert_list_into_free_list(list);
3832   }
3833 }
3834 
3835 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3836   decrease_used(bytes);
3837 }
3838 
3839 class G1FreeCollectionSetTask : public AbstractGangTask {
3840 private:
3841 
3842   // Closure applied to all regions in the collection set to do work that needs to
3843   // be done serially in a single thread.
3844   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3845   private:
3846     EvacuationInfo* _evacuation_info;
3847     const size_t* _surviving_young_words;
3848 
3849     // Bytes used in successfully evacuated regions before the evacuation.
3850     size_t _before_used_bytes;
3851     // Bytes used in unsucessfully evacuated regions before the evacuation
3852     size_t _after_used_bytes;
3853 
3854     size_t _bytes_allocated_in_old_since_last_gc;
3855 
3856     size_t _failure_used_words;
3857     size_t _failure_waste_words;
3858 
3859     FreeRegionList _local_free_list;
3860   public:
3861     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3862       HeapRegionClosure(),
3863       _evacuation_info(evacuation_info),
3864       _surviving_young_words(surviving_young_words),
3865       _before_used_bytes(0),
3866       _after_used_bytes(0),
3867       _bytes_allocated_in_old_since_last_gc(0),
3868       _failure_used_words(0),
3869       _failure_waste_words(0),
3870       _local_free_list("Local Region List for CSet Freeing") {
3871     }
3872 
3873     virtual bool do_heap_region(HeapRegion* r) {
3874       G1CollectedHeap* g1h = G1CollectedHeap::heap();
3875 
3876       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3877       g1h->clear_in_cset(r);
3878 
3879       if (r->is_young()) {
3880         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
3881                "Young index %d is wrong for region %u of type %s with %u young regions",
3882                r->young_index_in_cset(),
3883                r->hrm_index(),
3884                r->get_type_str(),
3885                g1h->collection_set()->young_region_length());
3886         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
3887         r->record_surv_words_in_group(words_survived);
3888       }
3889 
3890       if (!r->evacuation_failed()) {
3891         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
3892         _before_used_bytes += r->used();
3893         g1h->free_region(r,
3894                          &_local_free_list,
3895                          true, /* skip_remset */
3896                          true, /* skip_hot_card_cache */
3897                          true  /* locked */);
3898       } else {
3899         r->uninstall_surv_rate_group();
3900         r->set_young_index_in_cset(-1);
3901         r->set_evacuation_failed(false);
3902         // When moving a young gen region to old gen, we "allocate" that whole region
3903         // there. This is in addition to any already evacuated objects. Notify the
3904         // policy about that.
3905         // Old gen regions do not cause an additional allocation: both the objects
3906         // still in the region and the ones already moved are accounted for elsewhere.
3907         if (r->is_young()) {
3908           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
3909         }
3910         // The region is now considered to be old.
3911         r->set_old();
3912         // Do some allocation statistics accounting. Regions that failed evacuation
3913         // are always made old, so there is no need to update anything in the young
3914         // gen statistics, but we need to update old gen statistics.
3915         size_t used_words = r->marked_bytes() / HeapWordSize;
3916 
3917         _failure_used_words += used_words;
3918         _failure_waste_words += HeapRegion::GrainWords - used_words;
3919 
3920         g1h->old_set_add(r);
3921         _after_used_bytes += r->used();
3922       }
3923       return false;
3924     }
3925 
3926     void complete_work() {
3927       G1CollectedHeap* g1h = G1CollectedHeap::heap();
3928 
3929       _evacuation_info->set_regions_freed(_local_free_list.length());
3930       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
3931 
3932       g1h->prepend_to_freelist(&_local_free_list);
3933       g1h->decrement_summary_bytes(_before_used_bytes);
3934 
3935       G1Policy* policy = g1h->g1_policy();
3936       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
3937 
3938       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
3939     }
3940   };
3941 
3942   G1CollectionSet* _collection_set;
3943   G1SerialFreeCollectionSetClosure _cl;
3944   const size_t* _surviving_young_words;
3945 
3946   size_t _rs_lengths;
3947 
3948   volatile jint _serial_work_claim;
3949 
3950   struct WorkItem {
3951     uint region_idx;
3952     bool is_young;
3953     bool evacuation_failed;
3954 
3955     WorkItem(HeapRegion* r) {
3956       region_idx = r->hrm_index();
3957       is_young = r->is_young();
3958       evacuation_failed = r->evacuation_failed();
3959     }
3960   };
3961 
3962   volatile size_t _parallel_work_claim;
3963   size_t _num_work_items;
3964   WorkItem* _work_items;
3965 
3966   void do_serial_work() {
3967     // Need to grab the lock to be allowed to modify the old region list.
3968     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3969     _collection_set->iterate(&_cl);
3970   }
3971 
3972   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
3973     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3974 
3975     HeapRegion* r = g1h->region_at(region_idx);
3976     assert(!g1h->is_on_master_free_list(r), "sanity");
3977 
3978     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
3979 
3980     if (!is_young) {
3981       g1h->_hot_card_cache->reset_card_counts(r);
3982     }
3983 
3984     if (!evacuation_failed) {
3985       r->rem_set()->clear_locked();
3986     }
3987   }
3988 
3989   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
3990   private:
3991     size_t _cur_idx;
3992     WorkItem* _work_items;
3993   public:
3994     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
3995 
3996     virtual bool do_heap_region(HeapRegion* r) {
3997       _work_items[_cur_idx++] = WorkItem(r);
3998       return false;
3999     }
4000   };
4001 
4002   void prepare_work() {
4003     G1PrepareFreeCollectionSetClosure cl(_work_items);
4004     _collection_set->iterate(&cl);
4005   }
4006 
4007   void complete_work() {
4008     _cl.complete_work();
4009 
4010     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4011     policy->record_max_rs_lengths(_rs_lengths);
4012     policy->cset_regions_freed();
4013   }
4014 public:
4015   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4016     AbstractGangTask("G1 Free Collection Set"),
4017     _collection_set(collection_set),
4018     _cl(evacuation_info, surviving_young_words),
4019     _surviving_young_words(surviving_young_words),
4020     _rs_lengths(0),
4021     _serial_work_claim(0),
4022     _parallel_work_claim(0),
4023     _num_work_items(collection_set->region_length()),
4024     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4025     prepare_work();
4026   }
4027 
4028   ~G1FreeCollectionSetTask() {
4029     complete_work();
4030     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4031   }
4032 
4033   // Chunk size for work distribution. The chosen value has been determined experimentally
4034   // to be a good tradeoff between overhead and achievable parallelism.
4035   static uint chunk_size() { return 32; }
4036 
4037   virtual void work(uint worker_id) {
4038     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4039 
4040     // Claim serial work.
4041     if (_serial_work_claim == 0) {
4042       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4043       if (value == 0) {
4044         double serial_time = os::elapsedTime();
4045         do_serial_work();
4046         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4047       }
4048     }
4049 
4050     // Start parallel work.
4051     double young_time = 0.0;
4052     bool has_young_time = false;
4053     double non_young_time = 0.0;
4054     bool has_non_young_time = false;
4055 
4056     while (true) {
4057       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4058       size_t cur = end - chunk_size();
4059 
4060       if (cur >= _num_work_items) {
4061         break;
4062       }
4063 
4064       EventGCPhaseParallel event;
4065       double start_time = os::elapsedTime();
4066 
4067       end = MIN2(end, _num_work_items);
4068 
4069       for (; cur < end; cur++) {
4070         bool is_young = _work_items[cur].is_young;
4071 
4072         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4073 
4074         double end_time = os::elapsedTime();
4075         double time_taken = end_time - start_time;
4076         if (is_young) {
4077           young_time += time_taken;
4078           has_young_time = true;
4079           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4080         } else {
4081           non_young_time += time_taken;
4082           has_non_young_time = true;
4083           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4084         }
4085         start_time = end_time;
4086       }
4087     }
4088 
4089     if (has_young_time) {
4090       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4091     }
4092     if (has_non_young_time) {
4093       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4094     }
4095   }
4096 };
4097 
4098 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4099   _eden.clear();
4100 
4101   double free_cset_start_time = os::elapsedTime();
4102 
4103   {
4104     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4105     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4106 
4107     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4108 
4109     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4110                         cl.name(),
4111                         num_workers,
4112                         _collection_set.region_length());
4113     workers()->run_task(&cl, num_workers);
4114   }
4115   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4116 
4117   collection_set->clear();
4118 }
4119 
4120 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4121  private:
4122   FreeRegionList* _free_region_list;
4123   HeapRegionSet* _proxy_set;
4124   uint _humongous_objects_reclaimed;
4125   uint _humongous_regions_reclaimed;
4126   size_t _freed_bytes;
4127  public:
4128 
4129   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4130     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4131   }
4132 
4133   virtual bool do_heap_region(HeapRegion* r) {
4134     if (!r->is_starts_humongous()) {
4135       return false;
4136     }
4137 
4138     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4139 
4140     oop obj = (oop)r->bottom();
4141     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4142 
4143     // The following checks whether the humongous object is live are sufficient.
4144     // The main additional check (in addition to having a reference from the roots
4145     // or the young gen) is whether the humongous object has a remembered set entry.
4146     //
4147     // A humongous object cannot be live if there is no remembered set for it
4148     // because:
4149     // - there can be no references from within humongous starts regions referencing
4150     // the object because we never allocate other objects into them.
4151     // (I.e. there are no intra-region references that may be missed by the
4152     // remembered set)
4153     // - as soon there is a remembered set entry to the humongous starts region
4154     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4155     // until the end of a concurrent mark.
4156     //
4157     // It is not required to check whether the object has been found dead by marking
4158     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4159     // all objects allocated during that time are considered live.
4160     // SATB marking is even more conservative than the remembered set.
4161     // So if at this point in the collection there is no remembered set entry,
4162     // nobody has a reference to it.
4163     // At the start of collection we flush all refinement logs, and remembered sets
4164     // are completely up-to-date wrt to references to the humongous object.
4165     //
4166     // Other implementation considerations:
4167     // - never consider object arrays at this time because they would pose
4168     // considerable effort for cleaning up the the remembered sets. This is
4169     // required because stale remembered sets might reference locations that
4170     // are currently allocated into.
4171     uint region_idx = r->hrm_index();
4172     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4173         !r->rem_set()->is_empty()) {
4174       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",
4175                                region_idx,
4176                                (size_t)obj->size() * HeapWordSize,
4177                                p2i(r->bottom()),
4178                                r->rem_set()->occupied(),
4179                                r->rem_set()->strong_code_roots_list_length(),
4180                                next_bitmap->is_marked(r->bottom()),
4181                                g1h->is_humongous_reclaim_candidate(region_idx),
4182                                obj->is_typeArray()
4183                               );
4184       return false;
4185     }
4186 
4187     guarantee(obj->is_typeArray(),
4188               "Only eagerly reclaiming type arrays is supported, but the object "
4189               PTR_FORMAT " is not.", p2i(r->bottom()));
4190 
4191     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",
4192                              region_idx,
4193                              (size_t)obj->size() * HeapWordSize,
4194                              p2i(r->bottom()),
4195                              r->rem_set()->occupied(),
4196                              r->rem_set()->strong_code_roots_list_length(),
4197                              next_bitmap->is_marked(r->bottom()),
4198                              g1h->is_humongous_reclaim_candidate(region_idx),
4199                              obj->is_typeArray()
4200                             );
4201 
4202     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4203     cm->humongous_object_eagerly_reclaimed(r);
4204     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4205            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4206            region_idx,
4207            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4208            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4209     _humongous_objects_reclaimed++;
4210     do {
4211       HeapRegion* next = g1h->next_region_in_humongous(r);
4212       _freed_bytes += r->used();
4213       r->set_containing_set(NULL);
4214       _humongous_regions_reclaimed++;
4215       g1h->free_humongous_region(r, _free_region_list);
4216       r = next;
4217     } while (r != NULL);
4218 
4219     return false;
4220   }
4221 
4222   uint humongous_objects_reclaimed() {
4223     return _humongous_objects_reclaimed;
4224   }
4225 
4226   uint humongous_regions_reclaimed() {
4227     return _humongous_regions_reclaimed;
4228   }
4229 
4230   size_t bytes_freed() const {
4231     return _freed_bytes;
4232   }
4233 };
4234 
4235 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4236   assert_at_safepoint_on_vm_thread();
4237 
4238   if (!G1EagerReclaimHumongousObjects ||
4239       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4240     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4241     return;
4242   }
4243 
4244   double start_time = os::elapsedTime();
4245 
4246   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4247 
4248   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4249   heap_region_iterate(&cl);
4250 
4251   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4252 
4253   G1HRPrinter* hrp = hr_printer();
4254   if (hrp->is_active()) {
4255     FreeRegionListIterator iter(&local_cleanup_list);
4256     while (iter.more_available()) {
4257       HeapRegion* hr = iter.get_next();
4258       hrp->cleanup(hr);
4259     }
4260   }
4261 
4262   prepend_to_freelist(&local_cleanup_list);
4263   decrement_summary_bytes(cl.bytes_freed());
4264 
4265   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4266                                                                     cl.humongous_objects_reclaimed());
4267 }
4268 
4269 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4270 public:
4271   virtual bool do_heap_region(HeapRegion* r) {
4272     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4273     G1CollectedHeap::heap()->clear_in_cset(r);
4274     r->set_young_index_in_cset(-1);
4275     return false;
4276   }
4277 };
4278 
4279 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4280   G1AbandonCollectionSetClosure cl;
4281   collection_set->iterate(&cl);
4282 
4283   collection_set->clear();
4284   collection_set->stop_incremental_building();
4285 }
4286 
4287 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4288   return _allocator->is_retained_old_region(hr);
4289 }
4290 
4291 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4292   _eden.add(hr);
4293   _g1_policy->set_region_eden(hr);
4294 }
4295 
4296 #ifdef ASSERT
4297 
4298 class NoYoungRegionsClosure: public HeapRegionClosure {
4299 private:
4300   bool _success;
4301 public:
4302   NoYoungRegionsClosure() : _success(true) { }
4303   bool do_heap_region(HeapRegion* r) {
4304     if (r->is_young()) {
4305       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4306                             p2i(r->bottom()), p2i(r->end()));
4307       _success = false;
4308     }
4309     return false;
4310   }
4311   bool success() { return _success; }
4312 };
4313 
4314 bool G1CollectedHeap::check_young_list_empty() {
4315   bool ret = (young_regions_count() == 0);
4316 
4317   NoYoungRegionsClosure closure;
4318   heap_region_iterate(&closure);
4319   ret = ret && closure.success();
4320 
4321   return ret;
4322 }
4323 
4324 #endif // ASSERT
4325 
4326 class TearDownRegionSetsClosure : public HeapRegionClosure {
4327   HeapRegionSet *_old_set;
4328 
4329 public:
4330   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4331 
4332   bool do_heap_region(HeapRegion* r) {
4333     if (r->is_old()) {
4334       _old_set->remove(r);
4335     } else if(r->is_young()) {
4336       r->uninstall_surv_rate_group();
4337     } else {
4338       // We ignore free regions, we'll empty the free list afterwards.
4339       // We ignore humongous and archive regions, we're not tearing down these
4340       // sets.
4341       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4342              "it cannot be another type");
4343     }
4344     return false;
4345   }
4346 
4347   ~TearDownRegionSetsClosure() {
4348     assert(_old_set->is_empty(), "post-condition");
4349   }
4350 };
4351 
4352 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4353   assert_at_safepoint_on_vm_thread();
4354 
4355   if (!free_list_only) {
4356     TearDownRegionSetsClosure cl(&_old_set);
4357     heap_region_iterate(&cl);
4358 
4359     // Note that emptying the _young_list is postponed and instead done as
4360     // the first step when rebuilding the regions sets again. The reason for
4361     // this is that during a full GC string deduplication needs to know if
4362     // a collected region was young or old when the full GC was initiated.
4363   }
4364   _hrm.remove_all_free_regions();
4365 }
4366 
4367 void G1CollectedHeap::increase_used(size_t bytes) {
4368   _summary_bytes_used += bytes;
4369 }
4370 
4371 void G1CollectedHeap::decrease_used(size_t bytes) {
4372   assert(_summary_bytes_used >= bytes,
4373          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4374          _summary_bytes_used, bytes);
4375   _summary_bytes_used -= bytes;
4376 }
4377 
4378 void G1CollectedHeap::set_used(size_t bytes) {
4379   _summary_bytes_used = bytes;
4380 }
4381 
4382 class RebuildRegionSetsClosure : public HeapRegionClosure {
4383 private:
4384   bool _free_list_only;
4385 
4386   HeapRegionSet* _old_set;
4387   HeapRegionManager* _hrm;
4388 
4389   size_t _total_used;
4390 
4391 public:
4392   RebuildRegionSetsClosure(bool free_list_only,
4393                            HeapRegionSet* old_set,
4394                            HeapRegionManager* hrm) :
4395     _free_list_only(free_list_only),
4396     _old_set(old_set), _hrm(hrm), _total_used(0) {
4397     assert(_hrm->num_free_regions() == 0, "pre-condition");
4398     if (!free_list_only) {
4399       assert(_old_set->is_empty(), "pre-condition");
4400     }
4401   }
4402 
4403   bool do_heap_region(HeapRegion* r) {
4404     if (r->is_empty()) {
4405       assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4406       // Add free regions to the free list
4407       r->set_free();
4408       _hrm->insert_into_free_list(r);
4409     } else if (!_free_list_only) {
4410       assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4411 
4412       if (r->is_archive() || r->is_humongous()) {
4413         // We ignore archive and humongous regions. We left these sets unchanged.
4414       } else {
4415         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4416         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4417         r->move_to_old();
4418         _old_set->add(r);
4419       }
4420       _total_used += r->used();
4421     }
4422 
4423     return false;
4424   }
4425 
4426   size_t total_used() {
4427     return _total_used;
4428   }
4429 };
4430 
4431 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4432   assert_at_safepoint_on_vm_thread();
4433 
4434   if (!free_list_only) {
4435     _eden.clear();
4436     _survivor.clear();
4437   }
4438 
4439   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4440   heap_region_iterate(&cl);
4441 
4442   if (!free_list_only) {
4443     set_used(cl.total_used());
4444     if (_archive_allocator != NULL) {
4445       _archive_allocator->clear_used();
4446     }
4447   }
4448   assert(used() == recalculate_used(),
4449          "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4450          used(), recalculate_used());
4451 }
4452 
4453 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4454   HeapRegion* hr = heap_region_containing(p);
4455   return hr->is_in(p);
4456 }
4457 
4458 // Methods for the mutator alloc region
4459 
4460 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4461                                                       bool force) {
4462   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4463   bool should_allocate = g1_policy()->should_allocate_mutator_region();
4464   if (force || should_allocate) {
4465     HeapRegion* new_alloc_region = new_region(word_size,
4466                                               false /* is_old */,
4467                                               false /* do_expand */);
4468     if (new_alloc_region != NULL) {
4469       set_region_short_lived_locked(new_alloc_region);
4470       _hr_printer.alloc(new_alloc_region, !should_allocate);
4471       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4472       _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4473       return new_alloc_region;
4474     }
4475   }
4476   return NULL;
4477 }
4478 
4479 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4480                                                   size_t allocated_bytes) {
4481   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4482   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4483 
4484   collection_set()->add_eden_region(alloc_region);
4485   increase_used(allocated_bytes);
4486   _hr_printer.retire(alloc_region);
4487   // We update the eden sizes here, when the region is retired,
4488   // instead of when it's allocated, since this is the point that its
4489   // used space has been recorded in _summary_bytes_used.
4490   g1mm()->update_eden_size();
4491 }
4492 
4493 // Methods for the GC alloc regions
4494 
4495 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4496   if (dest.is_old()) {
4497     return true;
4498   } else {
4499     return survivor_regions_count() < g1_policy()->max_survivor_regions();
4500   }
4501 }
4502 
4503 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4504   assert(FreeList_lock->owned_by_self(), "pre-condition");
4505 
4506   if (!has_more_regions(dest)) {
4507     return NULL;
4508   }
4509 
4510   const bool is_survivor = dest.is_young();
4511 
4512   HeapRegion* new_alloc_region = new_region(word_size,
4513                                             !is_survivor,
4514                                             true /* do_expand */);
4515   if (new_alloc_region != NULL) {
4516     if (is_survivor) {
4517       new_alloc_region->set_survivor();
4518       _survivor.add(new_alloc_region);
4519       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4520     } else {
4521       new_alloc_region->set_old();
4522       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4523     }
4524     _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4525     _hr_printer.alloc(new_alloc_region);
4526     bool during_im = collector_state()->in_initial_mark_gc();
4527     new_alloc_region->note_start_of_copying(during_im);
4528     return new_alloc_region;
4529   }
4530   return NULL;
4531 }
4532 
4533 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4534                                              size_t allocated_bytes,
4535                                              InCSetState dest) {
4536   bool during_im = collector_state()->in_initial_mark_gc();
4537   alloc_region->note_end_of_copying(during_im);
4538   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4539   if (dest.is_old()) {
4540     old_set_add(alloc_region);
4541   }
4542   _hr_printer.retire(alloc_region);
4543 }
4544 
4545 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4546   bool expanded = false;
4547   uint index = _hrm.find_highest_free(&expanded);
4548 
4549   if (index != G1_NO_HRM_INDEX) {
4550     if (expanded) {
4551       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4552                                 HeapRegion::GrainWords * HeapWordSize);
4553     }
4554     _hrm.allocate_free_regions_starting_at(index, 1);
4555     return region_at(index);
4556   }
4557   return NULL;
4558 }
4559 
4560 // Optimized nmethod scanning
4561 
4562 class RegisterNMethodOopClosure: public OopClosure {
4563   G1CollectedHeap* _g1h;
4564   nmethod* _nm;
4565 
4566   template <class T> void do_oop_work(T* p) {
4567     T heap_oop = RawAccess<>::oop_load(p);
4568     if (!CompressedOops::is_null(heap_oop)) {
4569       oop obj = CompressedOops::decode_not_null(heap_oop);
4570       HeapRegion* hr = _g1h->heap_region_containing(obj);
4571       assert(!hr->is_continues_humongous(),
4572              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4573              " starting at " HR_FORMAT,
4574              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4575 
4576       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4577       hr->add_strong_code_root_locked(_nm);
4578     }
4579   }
4580 
4581 public:
4582   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4583     _g1h(g1h), _nm(nm) {}
4584 
4585   void do_oop(oop* p)       { do_oop_work(p); }
4586   void do_oop(narrowOop* p) { do_oop_work(p); }
4587 };
4588 
4589 class UnregisterNMethodOopClosure: public OopClosure {
4590   G1CollectedHeap* _g1h;
4591   nmethod* _nm;
4592 
4593   template <class T> void do_oop_work(T* p) {
4594     T heap_oop = RawAccess<>::oop_load(p);
4595     if (!CompressedOops::is_null(heap_oop)) {
4596       oop obj = CompressedOops::decode_not_null(heap_oop);
4597       HeapRegion* hr = _g1h->heap_region_containing(obj);
4598       assert(!hr->is_continues_humongous(),
4599              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4600              " starting at " HR_FORMAT,
4601              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4602 
4603       hr->remove_strong_code_root(_nm);
4604     }
4605   }
4606 
4607 public:
4608   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4609     _g1h(g1h), _nm(nm) {}
4610 
4611   void do_oop(oop* p)       { do_oop_work(p); }
4612   void do_oop(narrowOop* p) { do_oop_work(p); }
4613 };
4614 
4615 // Returns true if the reference points to an object that
4616 // can move in an incremental collection.
4617 bool G1CollectedHeap::is_scavengable(oop obj) {
4618   HeapRegion* hr = heap_region_containing(obj);
4619   return !hr->is_pinned();
4620 }
4621 
4622 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4623   guarantee(nm != NULL, "sanity");
4624   RegisterNMethodOopClosure reg_cl(this, nm);
4625   nm->oops_do(&reg_cl);
4626 }
4627 
4628 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4629   guarantee(nm != NULL, "sanity");
4630   UnregisterNMethodOopClosure reg_cl(this, nm);
4631   nm->oops_do(&reg_cl, true);
4632 }
4633 
4634 void G1CollectedHeap::purge_code_root_memory() {
4635   double purge_start = os::elapsedTime();
4636   G1CodeRootSet::purge();
4637   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4638   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4639 }
4640 
4641 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4642   G1CollectedHeap* _g1h;
4643 
4644 public:
4645   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4646     _g1h(g1h) {}
4647 
4648   void do_code_blob(CodeBlob* cb) {
4649     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4650     if (nm == NULL) {
4651       return;
4652     }
4653 
4654     if (ScavengeRootsInCode) {
4655       _g1h->register_nmethod(nm);
4656     }
4657   }
4658 };
4659 
4660 void G1CollectedHeap::rebuild_strong_code_roots() {
4661   RebuildStrongCodeRootClosure blob_cl(this);
4662   CodeCache::blobs_do(&blob_cl);
4663 }
4664 
4665 void G1CollectedHeap::initialize_serviceability() {
4666   _g1mm->initialize_serviceability();
4667 }
4668 
4669 MemoryUsage G1CollectedHeap::memory_usage() {
4670   return _g1mm->memory_usage();
4671 }
4672 
4673 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4674   return _g1mm->memory_managers();
4675 }
4676 
4677 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4678   return _g1mm->memory_pools();
4679 }