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