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/metadataOnStackMark.hpp"
  27 #include "classfile/stringTable.hpp"
  28 #include "classfile/symbolTable.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "gc/g1/bufferingOopClosure.hpp"
  32 #include "gc/g1/concurrentMarkThread.inline.hpp"
  33 #include "gc/g1/g1Allocator.inline.hpp"
  34 #include "gc/g1/g1CollectedHeap.inline.hpp"
  35 #include "gc/g1/g1CollectionSet.hpp"
  36 #include "gc/g1/g1CollectorPolicy.hpp"
  37 #include "gc/g1/g1CollectorState.hpp"
  38 #include "gc/g1/g1ConcurrentRefine.hpp"
  39 #include "gc/g1/g1ConcurrentRefineThread.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/g1SATBCardTableModRefBS.hpp"
  56 #include "gc/g1/g1StringDedup.hpp"
  57 #include "gc/g1/g1YCTypes.hpp"
  58 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  59 #include "gc/g1/heapRegion.inline.hpp"
  60 #include "gc/g1/heapRegionRemSet.hpp"
  61 #include "gc/g1/heapRegionSet.inline.hpp"
  62 #include "gc/g1/vm_operations_g1.hpp"
  63 #include "gc/shared/adaptiveSizePolicy.hpp"
  64 #include "gc/shared/gcHeapSummary.hpp"
  65 #include "gc/shared/gcId.hpp"
  66 #include "gc/shared/gcLocker.inline.hpp"
  67 #include "gc/shared/gcTimer.hpp"
  68 #include "gc/shared/gcTrace.hpp"
  69 #include "gc/shared/gcTraceTime.inline.hpp"
  70 #include "gc/shared/generationSpec.hpp"
  71 #include "gc/shared/isGCActiveMark.hpp"
  72 #include "gc/shared/preservedMarks.inline.hpp"
  73 #include "gc/shared/suspendibleThreadSet.hpp"
  74 #include "gc/shared/referenceProcessor.inline.hpp"
  75 #include "gc/shared/taskqueue.inline.hpp"
  76 #include "gc/shared/weakProcessor.hpp"
  77 #include "logging/log.hpp"
  78 #include "memory/allocation.hpp"
  79 #include "memory/iterator.hpp"
  80 #include "memory/resourceArea.hpp"
  81 #include "oops/oop.inline.hpp"
  82 #include "prims/resolvedMethodTable.hpp"
  83 #include "runtime/atomic.hpp"
  84 #include "runtime/init.hpp"
  85 #include "runtime/orderAccess.inline.hpp"
  86 #include "runtime/threadSMR.hpp"
  87 #include "runtime/vmThread.hpp"
  88 #include "utilities/align.hpp"
  89 #include "utilities/globalDefinitions.hpp"
  90 #include "utilities/stack.inline.hpp"
  91 
  92 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  93 
  94 // INVARIANTS/NOTES
  95 //
  96 // All allocation activity covered by the G1CollectedHeap interface is
  97 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  98 // and allocate_new_tlab, which are the "entry" points to the
  99 // allocation code from the rest of the JVM.  (Note that this does not
 100 // apply to TLAB allocation, which is not part of this interface: it
 101 // is done by clients of this interface.)
 102 
 103 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 104  private:
 105   size_t _num_dirtied;
 106   G1CollectedHeap* _g1h;
 107   G1CardTable* _g1_ct;
 108 
 109   HeapRegion* region_for_card(jbyte* card_ptr) const {
 110     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
 111   }
 112 
 113   bool will_become_free(HeapRegion* hr) const {
 114     // A region will be freed by free_collection_set if the region is in the
 115     // collection set and has not had an evacuation failure.
 116     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 117   }
 118 
 119  public:
 120   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 121     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
 122 
 123   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 124     HeapRegion* hr = region_for_card(card_ptr);
 125 
 126     // Should only dirty cards in regions that won't be freed.
 127     if (!will_become_free(hr)) {
 128       *card_ptr = G1CardTable::dirty_card_val();
 129       _num_dirtied++;
 130     }
 131 
 132     return true;
 133   }
 134 
 135   size_t num_dirtied()   const { return _num_dirtied; }
 136 };
 137 
 138 
 139 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 140   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 141 }
 142 
 143 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 144   // The from card cache is not the memory that is actually committed. So we cannot
 145   // take advantage of the zero_filled parameter.
 146   reset_from_card_cache(start_idx, num_regions);
 147 }
 148 
 149 
 150 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 151                                              MemRegion mr) {
 152   return new HeapRegion(hrs_index, bot(), mr);
 153 }
 154 
 155 // Private methods.
 156 
 157 HeapRegion*
 158 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 159   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 160   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 161     if (!_secondary_free_list.is_empty()) {
 162       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 163                                       "secondary_free_list has %u entries",
 164                                       _secondary_free_list.length());
 165       // It looks as if there are free regions available on the
 166       // secondary_free_list. Let's move them to the free_list and try
 167       // again to allocate from it.
 168       append_secondary_free_list();
 169 
 170       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 171              "empty we should have moved at least one entry to the free_list");
 172       HeapRegion* res = _hrm.allocate_free_region(is_old);
 173       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 174                                       "allocated " HR_FORMAT " from secondary_free_list",
 175                                       HR_FORMAT_PARAMS(res));
 176       return res;
 177     }
 178 
 179     // Wait here until we get notified either when (a) there are no
 180     // more free regions coming or (b) some regions have been moved on
 181     // the secondary_free_list.
 182     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 183   }
 184 
 185   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 186                                   "could not allocate from secondary_free_list");
 187   return NULL;
 188 }
 189 
 190 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 191   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 192          "the only time we use this to allocate a humongous region is "
 193          "when we are allocating a single humongous region");
 194 
 195   HeapRegion* res;
 196   if (G1StressConcRegionFreeing) {
 197     if (!_secondary_free_list.is_empty()) {
 198       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 199                                       "forced to look at the secondary_free_list");
 200       res = new_region_try_secondary_free_list(is_old);
 201       if (res != NULL) {
 202         return res;
 203       }
 204     }
 205   }
 206 
 207   res = _hrm.allocate_free_region(is_old);
 208 
 209   if (res == NULL) {
 210     log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 211                                     "res == NULL, trying the secondary_free_list");
 212     res = new_region_try_secondary_free_list(is_old);
 213   }
 214   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 215     // Currently, only attempts to allocate GC alloc regions set
 216     // do_expand to true. So, we should only reach here during a
 217     // safepoint. If this assumption changes we might have to
 218     // reconsider the use of _expand_heap_after_alloc_failure.
 219     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 220 
 221     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 222                               word_size * HeapWordSize);
 223 
 224     if (expand(word_size * HeapWordSize)) {
 225       // Given that expand() succeeded in expanding the heap, and we
 226       // always expand the heap by an amount aligned to the heap
 227       // region size, the free list should in theory not be empty.
 228       // In either case allocate_free_region() will check for NULL.
 229       res = _hrm.allocate_free_region(is_old);
 230     } else {
 231       _expand_heap_after_alloc_failure = false;
 232     }
 233   }
 234   return res;
 235 }
 236 
 237 HeapWord*
 238 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 239                                                            uint num_regions,
 240                                                            size_t word_size,
 241                                                            AllocationContext_t context) {
 242   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 243   assert(is_humongous(word_size), "word_size should be humongous");
 244   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 245 
 246   // Index of last region in the series.
 247   uint last = first + num_regions - 1;
 248 
 249   // We need to initialize the region(s) we just discovered. This is
 250   // a bit tricky given that it can happen concurrently with
 251   // refinement threads refining cards on these regions and
 252   // potentially wanting to refine the BOT as they are scanning
 253   // those cards (this can happen shortly after a cleanup; see CR
 254   // 6991377). So we have to set up the region(s) carefully and in
 255   // a specific order.
 256 
 257   // The word size sum of all the regions we will allocate.
 258   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 259   assert(word_size <= word_size_sum, "sanity");
 260 
 261   // This will be the "starts humongous" region.
 262   HeapRegion* first_hr = region_at(first);
 263   // The header of the new object will be placed at the bottom of
 264   // the first region.
 265   HeapWord* new_obj = first_hr->bottom();
 266   // This will be the new top of the new object.
 267   HeapWord* obj_top = new_obj + word_size;
 268 
 269   // First, we need to zero the header of the space that we will be
 270   // allocating. When we update top further down, some refinement
 271   // threads might try to scan the region. By zeroing the header we
 272   // ensure that any thread that will try to scan the region will
 273   // come across the zero klass word and bail out.
 274   //
 275   // NOTE: It would not have been correct to have used
 276   // CollectedHeap::fill_with_object() and make the space look like
 277   // an int array. The thread that is doing the allocation will
 278   // later update the object header to a potentially different array
 279   // type and, for a very short period of time, the klass and length
 280   // fields will be inconsistent. This could cause a refinement
 281   // thread to calculate the object size incorrectly.
 282   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 283 
 284   // Next, pad out the unused tail of the last region with filler
 285   // objects, for improved usage accounting.
 286   // How many words we use for filler objects.
 287   size_t word_fill_size = word_size_sum - word_size;
 288 
 289   // How many words memory we "waste" which cannot hold a filler object.
 290   size_t words_not_fillable = 0;
 291 
 292   if (word_fill_size >= min_fill_size()) {
 293     fill_with_objects(obj_top, word_fill_size);
 294   } else if (word_fill_size > 0) {
 295     // We have space to fill, but we cannot fit an object there.
 296     words_not_fillable = word_fill_size;
 297     word_fill_size = 0;
 298   }
 299 
 300   // We will set up the first region as "starts humongous". This
 301   // will also update the BOT covering all the regions to reflect
 302   // that there is a single object that starts at the bottom of the
 303   // first region.
 304   first_hr->set_starts_humongous(obj_top, word_fill_size);
 305   first_hr->set_allocation_context(context);
 306   // Then, if there are any, we will set up the "continues
 307   // humongous" regions.
 308   HeapRegion* hr = NULL;
 309   for (uint i = first + 1; i <= last; ++i) {
 310     hr = region_at(i);
 311     hr->set_continues_humongous(first_hr);
 312     hr->set_allocation_context(context);
 313   }
 314 
 315   // Up to this point no concurrent thread would have been able to
 316   // do any scanning on any region in this series. All the top
 317   // fields still point to bottom, so the intersection between
 318   // [bottom,top] and [card_start,card_end] will be empty. Before we
 319   // update the top fields, we'll do a storestore to make sure that
 320   // no thread sees the update to top before the zeroing of the
 321   // object header and the BOT initialization.
 322   OrderAccess::storestore();
 323 
 324   // Now, we will update the top fields of the "continues humongous"
 325   // regions except the last one.
 326   for (uint i = first; i < last; ++i) {
 327     hr = region_at(i);
 328     hr->set_top(hr->end());
 329   }
 330 
 331   hr = region_at(last);
 332   // If we cannot fit a filler object, we must set top to the end
 333   // of the humongous object, otherwise we cannot iterate the heap
 334   // and the BOT will not be complete.
 335   hr->set_top(hr->end() - words_not_fillable);
 336 
 337   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 338          "obj_top should be in last region");
 339 
 340   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 341 
 342   assert(words_not_fillable == 0 ||
 343          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 344          "Miscalculation in humongous allocation");
 345 
 346   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 347 
 348   for (uint i = first; i <= last; ++i) {
 349     hr = region_at(i);
 350     _humongous_set.add(hr);
 351     _hr_printer.alloc(hr);
 352   }
 353 
 354   return new_obj;
 355 }
 356 
 357 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 358   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 359   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 360 }
 361 
 362 // If could fit into free regions w/o expansion, try.
 363 // Otherwise, if can expand, do so.
 364 // Otherwise, if using ex regions might help, try with ex given back.
 365 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 366   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 367 
 368   _verifier->verify_region_sets_optional();
 369 
 370   uint first = G1_NO_HRM_INDEX;
 371   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 372 
 373   if (obj_regions == 1) {
 374     // Only one region to allocate, try to use a fast path by directly allocating
 375     // from the free lists. Do not try to expand here, we will potentially do that
 376     // later.
 377     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 378     if (hr != NULL) {
 379       first = hr->hrm_index();
 380     }
 381   } else {
 382     // We can't allocate humongous regions spanning more than one region while
 383     // cleanupComplete() is running, since some of the regions we find to be
 384     // empty might not yet be added to the free list. It is not straightforward
 385     // to know in which list they are on so that we can remove them. We only
 386     // need to do this if we need to allocate more than one region to satisfy the
 387     // current humongous allocation request. If we are only allocating one region
 388     // we use the one-region region allocation code (see above), that already
 389     // potentially waits for regions from the secondary free list.
 390     wait_while_free_regions_coming();
 391     append_secondary_free_list_if_not_empty_with_lock();
 392 
 393     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 394     // are lucky enough to find some.
 395     first = _hrm.find_contiguous_only_empty(obj_regions);
 396     if (first != G1_NO_HRM_INDEX) {
 397       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 398     }
 399   }
 400 
 401   if (first == G1_NO_HRM_INDEX) {
 402     // Policy: We could not find enough regions for the humongous object in the
 403     // free list. Look through the heap to find a mix of free and uncommitted regions.
 404     // If so, try expansion.
 405     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 406     if (first != G1_NO_HRM_INDEX) {
 407       // We found something. Make sure these regions are committed, i.e. expand
 408       // the heap. Alternatively we could do a defragmentation GC.
 409       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 410                                     word_size * HeapWordSize);
 411 
 412       _hrm.expand_at(first, obj_regions, workers());
 413       g1_policy()->record_new_heap_size(num_regions());
 414 
 415 #ifdef ASSERT
 416       for (uint i = first; i < first + obj_regions; ++i) {
 417         HeapRegion* hr = region_at(i);
 418         assert(hr->is_free(), "sanity");
 419         assert(hr->is_empty(), "sanity");
 420         assert(is_on_master_free_list(hr), "sanity");
 421       }
 422 #endif
 423       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 424     } else {
 425       // Policy: Potentially trigger a defragmentation GC.
 426     }
 427   }
 428 
 429   HeapWord* result = NULL;
 430   if (first != G1_NO_HRM_INDEX) {
 431     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 432                                                        word_size, context);
 433     assert(result != NULL, "it should always return a valid result");
 434 
 435     // A successful humongous object allocation changes the used space
 436     // information of the old generation so we need to recalculate the
 437     // sizes and update the jstat counters here.
 438     g1mm()->update_sizes();
 439   }
 440 
 441   _verifier->verify_region_sets_optional();
 442 
 443   return result;
 444 }
 445 
 446 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 447   assert_heap_not_locked_and_not_at_safepoint();
 448   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 449 
 450   return attempt_allocation(word_size);
 451 }
 452 
 453 HeapWord*
 454 G1CollectedHeap::mem_allocate(size_t word_size,
 455                               bool*  gc_overhead_limit_was_exceeded) {
 456   assert_heap_not_locked_and_not_at_safepoint();
 457 
 458   if (is_humongous(word_size)) {
 459     return attempt_allocation_humongous(word_size);
 460   }
 461   return attempt_allocation(word_size);
 462 }
 463 
 464 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 465                                                    AllocationContext_t context) {
 466   ResourceMark rm; // For retrieving the thread names in log messages.
 467 
 468   // Make sure you read the note in attempt_allocation_humongous().
 469 
 470   assert_heap_not_locked_and_not_at_safepoint();
 471   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 472          "be called for humongous allocation requests");
 473 
 474   // We should only get here after the first-level allocation attempt
 475   // (attempt_allocation()) failed to allocate.
 476 
 477   // We will loop until a) we manage to successfully perform the
 478   // allocation or b) we successfully schedule a collection which
 479   // fails to perform the allocation. b) is the only case when we'll
 480   // return NULL.
 481   HeapWord* result = NULL;
 482   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 483     bool should_try_gc;
 484     uint gc_count_before;
 485 
 486     {
 487       MutexLockerEx x(Heap_lock);
 488       result = _allocator->attempt_allocation_locked(word_size, context);
 489       if (result != NULL) {
 490         return result;
 491       }
 492 
 493       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 494       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 495       // waiting because the GCLocker is active to not wait too long.
 496       if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
 497         // No need for an ergo message here, can_expand_young_list() does this when
 498         // it returns true.
 499         result = _allocator->attempt_allocation_force(word_size, context);
 500         if (result != NULL) {
 501           return result;
 502         }
 503       }
 504       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 505       // the GCLocker initiated GC has been performed and then retry. This includes
 506       // the case when the GC Locker is not active but has not been performed.
 507       should_try_gc = !GCLocker::needs_gc();
 508       // Read the GC count while still holding the Heap_lock.
 509       gc_count_before = total_collections();
 510     }
 511 
 512     if (should_try_gc) {
 513       bool succeeded;
 514       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 515                                    GCCause::_g1_inc_collection_pause);
 516       if (result != NULL) {
 517         assert(succeeded, "only way to get back a non-NULL result");
 518         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 519                              Thread::current()->name(), p2i(result));
 520         return result;
 521       }
 522 
 523       if (succeeded) {
 524         // We successfully scheduled a collection which failed to allocate. No
 525         // point in trying to allocate further. We'll just return NULL.
 526         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 527                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 528         return NULL;
 529       }
 530       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 531                            Thread::current()->name(), word_size);
 532     } else {
 533       // Failed to schedule a collection.
 534       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 535         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 536                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 537         return NULL;
 538       }
 539       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 540       // The GCLocker is either active or the GCLocker initiated
 541       // GC has not yet been performed. Stall until it is and
 542       // then retry the allocation.
 543       GCLocker::stall_until_clear();
 544       gclocker_retry_count += 1;
 545     }
 546 
 547     // We can reach here if we were unsuccessful in scheduling a
 548     // collection (because another thread beat us to it) or if we were
 549     // stalled due to the GC locker. In either can we should retry the
 550     // allocation attempt in case another thread successfully
 551     // performed a collection and reclaimed enough space. We do the
 552     // first attempt (without holding the Heap_lock) here and the
 553     // follow-on attempt will be at the start of the next loop
 554     // iteration (after taking the Heap_lock).
 555 
 556     result = _allocator->attempt_allocation(word_size, context);
 557     if (result != NULL) {
 558       return result;
 559     }
 560 
 561     // Give a warning if we seem to be looping forever.
 562     if ((QueuedAllocationWarningCount > 0) &&
 563         (try_count % QueuedAllocationWarningCount == 0)) {
 564       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 565                              Thread::current()->name(), try_count, word_size);
 566     }
 567   }
 568 
 569   ShouldNotReachHere();
 570   return NULL;
 571 }
 572 
 573 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 574   assert_at_safepoint(true /* should_be_vm_thread */);
 575   if (_archive_allocator == NULL) {
 576     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 577   }
 578 }
 579 
 580 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 581   // Allocations in archive regions cannot be of a size that would be considered
 582   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 583   // may be different at archive-restore time.
 584   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 585 }
 586 
 587 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 588   assert_at_safepoint(true /* should_be_vm_thread */);
 589   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 590   if (is_archive_alloc_too_large(word_size)) {
 591     return NULL;
 592   }
 593   return _archive_allocator->archive_mem_allocate(word_size);
 594 }
 595 
 596 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 597                                               size_t end_alignment_in_bytes) {
 598   assert_at_safepoint(true /* should_be_vm_thread */);
 599   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 600 
 601   // Call complete_archive to do the real work, filling in the MemRegion
 602   // array with the archive regions.
 603   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 604   delete _archive_allocator;
 605   _archive_allocator = NULL;
 606 }
 607 
 608 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 609   assert(ranges != NULL, "MemRegion array NULL");
 610   assert(count != 0, "No MemRegions provided");
 611   MemRegion reserved = _hrm.reserved();
 612   for (size_t i = 0; i < count; i++) {
 613     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 614       return false;
 615     }
 616   }
 617   return true;
 618 }
 619 
 620 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 621                                             size_t count,
 622                                             bool open) {
 623   assert(!is_init_completed(), "Expect to be called at JVM init time");
 624   assert(ranges != NULL, "MemRegion array NULL");
 625   assert(count != 0, "No MemRegions provided");
 626   MutexLockerEx x(Heap_lock);
 627 
 628   MemRegion reserved = _hrm.reserved();
 629   HeapWord* prev_last_addr = NULL;
 630   HeapRegion* prev_last_region = NULL;
 631 
 632   // Temporarily disable pretouching of heap pages. This interface is used
 633   // when mmap'ing archived heap data in, so pre-touching is wasted.
 634   FlagSetting fs(AlwaysPreTouch, false);
 635 
 636   // Enable archive object checking used by G1MarkSweep. We have to let it know
 637   // about each archive range, so that objects in those ranges aren't marked.
 638   G1ArchiveAllocator::enable_archive_object_check();
 639 
 640   // For each specified MemRegion range, allocate the corresponding G1
 641   // regions and mark them as archive regions. We expect the ranges
 642   // in ascending starting address order, without overlap.
 643   for (size_t i = 0; i < count; i++) {
 644     MemRegion curr_range = ranges[i];
 645     HeapWord* start_address = curr_range.start();
 646     size_t word_size = curr_range.word_size();
 647     HeapWord* last_address = curr_range.last();
 648     size_t commits = 0;
 649 
 650     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 651               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 652               p2i(start_address), p2i(last_address));
 653     guarantee(start_address > prev_last_addr,
 654               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 655               p2i(start_address), p2i(prev_last_addr));
 656     prev_last_addr = last_address;
 657 
 658     // Check for ranges that start in the same G1 region in which the previous
 659     // range ended, and adjust the start address so we don't try to allocate
 660     // the same region again. If the current range is entirely within that
 661     // region, skip it, just adjusting the recorded top.
 662     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 663     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 664       start_address = start_region->end();
 665       if (start_address > last_address) {
 666         increase_used(word_size * HeapWordSize);
 667         start_region->set_top(last_address + 1);
 668         continue;
 669       }
 670       start_region->set_top(start_address);
 671       curr_range = MemRegion(start_address, last_address + 1);
 672       start_region = _hrm.addr_to_region(start_address);
 673     }
 674 
 675     // Perform the actual region allocation, exiting if it fails.
 676     // Then note how much new space we have allocated.
 677     if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
 678       return false;
 679     }
 680     increase_used(word_size * HeapWordSize);
 681     if (commits != 0) {
 682       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 683                                 HeapRegion::GrainWords * HeapWordSize * commits);
 684 
 685     }
 686 
 687     // Mark each G1 region touched by the range as archive, add it to
 688     // the old set, and set the allocation context and top.
 689     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 690     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 691     prev_last_region = last_region;
 692 
 693     while (curr_region != NULL) {
 694       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 695              "Region already in use (index %u)", curr_region->hrm_index());
 696       curr_region->set_allocation_context(AllocationContext::system());
 697       if (open) {
 698         curr_region->set_open_archive();
 699       } else {
 700         curr_region->set_closed_archive();
 701       }
 702       _hr_printer.alloc(curr_region);
 703       _old_set.add(curr_region);
 704       HeapWord* top;
 705       HeapRegion* next_region;
 706       if (curr_region != last_region) {
 707         top = curr_region->end();
 708         next_region = _hrm.next_region_in_heap(curr_region);
 709       } else {
 710         top = last_address + 1;
 711         next_region = NULL;
 712       }
 713       curr_region->set_top(top);
 714       curr_region->set_first_dead(top);
 715       curr_region->set_end_of_live(top);
 716       curr_region = next_region;
 717     }
 718 
 719     // Notify mark-sweep of the archive
 720     G1ArchiveAllocator::set_range_archive(curr_range, open);
 721   }
 722   return true;
 723 }
 724 
 725 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 726   assert(!is_init_completed(), "Expect to be called at JVM init time");
 727   assert(ranges != NULL, "MemRegion array NULL");
 728   assert(count != 0, "No MemRegions provided");
 729   MemRegion reserved = _hrm.reserved();
 730   HeapWord *prev_last_addr = NULL;
 731   HeapRegion* prev_last_region = NULL;
 732 
 733   // For each MemRegion, create filler objects, if needed, in the G1 regions
 734   // that contain the address range. The address range actually within the
 735   // MemRegion will not be modified. That is assumed to have been initialized
 736   // elsewhere, probably via an mmap of archived heap data.
 737   MutexLockerEx x(Heap_lock);
 738   for (size_t i = 0; i < count; i++) {
 739     HeapWord* start_address = ranges[i].start();
 740     HeapWord* last_address = ranges[i].last();
 741 
 742     assert(reserved.contains(start_address) && reserved.contains(last_address),
 743            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 744            p2i(start_address), p2i(last_address));
 745     assert(start_address > prev_last_addr,
 746            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 747            p2i(start_address), p2i(prev_last_addr));
 748 
 749     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 750     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 751     HeapWord* bottom_address = start_region->bottom();
 752 
 753     // Check for a range beginning in the same region in which the
 754     // previous one ended.
 755     if (start_region == prev_last_region) {
 756       bottom_address = prev_last_addr + 1;
 757     }
 758 
 759     // Verify that the regions were all marked as archive regions by
 760     // alloc_archive_regions.
 761     HeapRegion* curr_region = start_region;
 762     while (curr_region != NULL) {
 763       guarantee(curr_region->is_archive(),
 764                 "Expected archive region at index %u", curr_region->hrm_index());
 765       if (curr_region != last_region) {
 766         curr_region = _hrm.next_region_in_heap(curr_region);
 767       } else {
 768         curr_region = NULL;
 769       }
 770     }
 771 
 772     prev_last_addr = last_address;
 773     prev_last_region = last_region;
 774 
 775     // Fill the memory below the allocated range with dummy object(s),
 776     // if the region bottom does not match the range start, or if the previous
 777     // range ended within the same G1 region, and there is a gap.
 778     if (start_address != bottom_address) {
 779       size_t fill_size = pointer_delta(start_address, bottom_address);
 780       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 781       increase_used(fill_size * HeapWordSize);
 782     }
 783   }
 784 }
 785 
 786 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) {
 787   assert_heap_not_locked_and_not_at_safepoint();
 788   assert(!is_humongous(word_size), "attempt_allocation() should not "
 789          "be called for humongous allocation requests");
 790 
 791   AllocationContext_t context = AllocationContext::current();
 792   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 793 
 794   if (result == NULL) {
 795     result = attempt_allocation_slow(word_size, context);
 796   }
 797   assert_heap_not_locked();
 798   if (result != NULL) {
 799     dirty_young_block(result, word_size);
 800   }
 801   return result;
 802 }
 803 
 804 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 805   assert(!is_init_completed(), "Expect to be called at JVM init time");
 806   assert(ranges != NULL, "MemRegion array NULL");
 807   assert(count != 0, "No MemRegions provided");
 808   MemRegion reserved = _hrm.reserved();
 809   HeapWord* prev_last_addr = NULL;
 810   HeapRegion* prev_last_region = NULL;
 811   size_t size_used = 0;
 812   size_t uncommitted_regions = 0;
 813 
 814   // For each Memregion, free the G1 regions that constitute it, and
 815   // notify mark-sweep that the range is no longer to be considered 'archive.'
 816   MutexLockerEx x(Heap_lock);
 817   for (size_t i = 0; i < count; i++) {
 818     HeapWord* start_address = ranges[i].start();
 819     HeapWord* last_address = ranges[i].last();
 820 
 821     assert(reserved.contains(start_address) && reserved.contains(last_address),
 822            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 823            p2i(start_address), p2i(last_address));
 824     assert(start_address > prev_last_addr,
 825            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 826            p2i(start_address), p2i(prev_last_addr));
 827     size_used += ranges[i].byte_size();
 828     prev_last_addr = last_address;
 829 
 830     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 831     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 832 
 833     // Check for ranges that start in the same G1 region in which the previous
 834     // range ended, and adjust the start address so we don't try to free
 835     // the same region again. If the current range is entirely within that
 836     // region, skip it.
 837     if (start_region == prev_last_region) {
 838       start_address = start_region->end();
 839       if (start_address > last_address) {
 840         continue;
 841       }
 842       start_region = _hrm.addr_to_region(start_address);
 843     }
 844     prev_last_region = last_region;
 845 
 846     // After verifying that each region was marked as an archive region by
 847     // alloc_archive_regions, set it free and empty and uncommit it.
 848     HeapRegion* curr_region = start_region;
 849     while (curr_region != NULL) {
 850       guarantee(curr_region->is_archive(),
 851                 "Expected archive region at index %u", curr_region->hrm_index());
 852       uint curr_index = curr_region->hrm_index();
 853       _old_set.remove(curr_region);
 854       curr_region->set_free();
 855       curr_region->set_top(curr_region->bottom());
 856       if (curr_region != last_region) {
 857         curr_region = _hrm.next_region_in_heap(curr_region);
 858       } else {
 859         curr_region = NULL;
 860       }
 861       _hrm.shrink_at(curr_index, 1);
 862       uncommitted_regions++;
 863     }
 864 
 865     // Notify mark-sweep that this is no longer an archive range.
 866     G1ArchiveAllocator::set_range_archive(ranges[i], false);
 867   }
 868 
 869   if (uncommitted_regions != 0) {
 870     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 871                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 872   }
 873   decrease_used(size_used);
 874 }
 875 
 876 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 877   ResourceMark rm; // For retrieving the thread names in log messages.
 878 
 879   // The structure of this method has a lot of similarities to
 880   // attempt_allocation_slow(). The reason these two were not merged
 881   // into a single one is that such a method would require several "if
 882   // allocation is not humongous do this, otherwise do that"
 883   // conditional paths which would obscure its flow. In fact, an early
 884   // version of this code did use a unified method which was harder to
 885   // follow and, as a result, it had subtle bugs that were hard to
 886   // track down. So keeping these two methods separate allows each to
 887   // be more readable. It will be good to keep these two in sync as
 888   // much as possible.
 889 
 890   assert_heap_not_locked_and_not_at_safepoint();
 891   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 892          "should only be called for humongous allocations");
 893 
 894   // Humongous objects can exhaust the heap quickly, so we should check if we
 895   // need to start a marking cycle at each humongous object allocation. We do
 896   // the check before we do the actual allocation. The reason for doing it
 897   // before the allocation is that we avoid having to keep track of the newly
 898   // allocated memory while we do a GC.
 899   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 900                                            word_size)) {
 901     collect(GCCause::_g1_humongous_allocation);
 902   }
 903 
 904   // We will loop until a) we manage to successfully perform the
 905   // allocation or b) we successfully schedule a collection which
 906   // fails to perform the allocation. b) is the only case when we'll
 907   // return NULL.
 908   HeapWord* result = NULL;
 909   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 910     bool should_try_gc;
 911     uint gc_count_before;
 912 
 913 
 914     {
 915       MutexLockerEx x(Heap_lock);
 916 
 917       // Given that humongous objects are not allocated in young
 918       // regions, we'll first try to do the allocation without doing a
 919       // collection hoping that there's enough space in the heap.
 920       result = humongous_obj_allocate(word_size, AllocationContext::current());
 921       if (result != NULL) {
 922         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 923         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 924         return result;
 925       }
 926 
 927       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 928       // the GCLocker initiated GC has been performed and then retry. This includes
 929       // the case when the GC Locker is not active but has not been performed.
 930       should_try_gc = !GCLocker::needs_gc();
 931       // Read the GC count while still holding the Heap_lock.
 932       gc_count_before = total_collections();
 933     }
 934 
 935     if (should_try_gc) {
 936       bool succeeded;
 937       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 938                                    GCCause::_g1_humongous_allocation);
 939       if (result != NULL) {
 940         assert(succeeded, "only way to get back a non-NULL result");
 941         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 942                              Thread::current()->name(), p2i(result));
 943         return result;
 944       }
 945 
 946       if (succeeded) {
 947         // We successfully scheduled a collection which failed to allocate. No
 948         // point in trying to allocate further. We'll just return NULL.
 949         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 950                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 951         return NULL;
 952       }
 953       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 954                            Thread::current()->name(), word_size);
 955     } else {
 956       // Failed to schedule a collection.
 957       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 958         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 959                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 960         return NULL;
 961       }
 962       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 963       // The GCLocker is either active or the GCLocker initiated
 964       // GC has not yet been performed. Stall until it is and
 965       // then retry the allocation.
 966       GCLocker::stall_until_clear();
 967       gclocker_retry_count += 1;
 968     }
 969 
 970 
 971     // We can reach here if we were unsuccessful in scheduling a
 972     // collection (because another thread beat us to it) or if we were
 973     // stalled due to the GC locker. In either can we should retry the
 974     // allocation attempt in case another thread successfully
 975     // performed a collection and reclaimed enough space.
 976     // Humongous object allocation always needs a lock, so we wait for the retry
 977     // in the next iteration of the loop, unlike for the regular iteration case.
 978     // Give a warning if we seem to be looping forever.
 979 
 980     if ((QueuedAllocationWarningCount > 0) &&
 981         (try_count % QueuedAllocationWarningCount == 0)) {
 982       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 983                              Thread::current()->name(), try_count, word_size);
 984     }
 985   }
 986 
 987   ShouldNotReachHere();
 988   return NULL;
 989 }
 990 
 991 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 992                                                            AllocationContext_t context,
 993                                                            bool expect_null_mutator_alloc_region) {
 994   assert_at_safepoint(true /* should_be_vm_thread */);
 995   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
 996          "the current alloc region was unexpectedly found to be non-NULL");
 997 
 998   if (!is_humongous(word_size)) {
 999     return _allocator->attempt_allocation_locked(word_size, context);
1000   } else {
1001     HeapWord* result = humongous_obj_allocate(word_size, context);
1002     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1003       collector_state()->set_initiate_conc_mark_if_possible(true);
1004     }
1005     return result;
1006   }
1007 
1008   ShouldNotReachHere();
1009 }
1010 
1011 class PostCompactionPrinterClosure: public HeapRegionClosure {
1012 private:
1013   G1HRPrinter* _hr_printer;
1014 public:
1015   bool do_heap_region(HeapRegion* hr) {
1016     assert(!hr->is_young(), "not expecting to find young regions");
1017     _hr_printer->post_compaction(hr);
1018     return false;
1019   }
1020 
1021   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1022     : _hr_printer(hr_printer) { }
1023 };
1024 
1025 void G1CollectedHeap::print_hrm_post_compaction() {
1026   if (_hr_printer.is_active()) {
1027     PostCompactionPrinterClosure cl(hr_printer());
1028     heap_region_iterate(&cl);
1029   }
1030 }
1031 
1032 void G1CollectedHeap::abort_concurrent_cycle() {
1033   // Note: When we have a more flexible GC logging framework that
1034   // allows us to add optional attributes to a GC log record we
1035   // could consider timing and reporting how long we wait in the
1036   // following two methods.
1037   wait_while_free_regions_coming();
1038   // If we start the compaction before the CM threads finish
1039   // scanning the root regions we might trip them over as we'll
1040   // be moving objects / updating references. So let's wait until
1041   // they are done. By telling them to abort, they should complete
1042   // early.
1043   _cm->root_regions()->abort();
1044   _cm->root_regions()->wait_until_scan_finished();
1045   append_secondary_free_list_if_not_empty_with_lock();
1046 
1047   // Disable discovery and empty the discovered lists
1048   // for the CM ref processor.
1049   ref_processor_cm()->disable_discovery();
1050   ref_processor_cm()->abandon_partial_discovery();
1051   ref_processor_cm()->verify_no_references_recorded();
1052 
1053   // Abandon current iterations of concurrent marking and concurrent
1054   // refinement, if any are in progress.
1055   concurrent_mark()->abort();
1056 }
1057 
1058 void G1CollectedHeap::prepare_heap_for_full_collection() {
1059   // Make sure we'll choose a new allocation region afterwards.
1060   _allocator->release_mutator_alloc_region();
1061   _allocator->abandon_gc_alloc_regions();
1062   g1_rem_set()->cleanupHRRS();
1063 
1064   // We may have added regions to the current incremental collection
1065   // set between the last GC or pause and now. We need to clear the
1066   // incremental collection set and then start rebuilding it afresh
1067   // after this full GC.
1068   abandon_collection_set(collection_set());
1069 
1070   tear_down_region_sets(false /* free_list_only */);
1071   collector_state()->set_gcs_are_young(true);
1072 }
1073 
1074 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1075   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1076   assert(used() == recalculate_used(), "Should be equal");
1077   _verifier->verify_region_sets_optional();
1078   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1079   _verifier->check_bitmaps("Full GC Start");
1080 }
1081 
1082 void G1CollectedHeap::prepare_heap_for_mutators() {
1083   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1084   ClassLoaderDataGraph::purge();
1085   MetaspaceAux::verify_metrics();
1086 
1087   // Prepare heap for normal collections.
1088   assert(num_free_regions() == 0, "we should not have added any free regions");
1089   rebuild_region_sets(false /* free_list_only */);
1090   abort_refinement();
1091   resize_if_necessary_after_full_collection();
1092 
1093   // Rebuild the strong code root lists for each region
1094   rebuild_strong_code_roots();
1095 
1096   // Start a new incremental collection set for the next pause
1097   start_new_collection_set();
1098 
1099   _allocator->init_mutator_alloc_region();
1100 
1101   // Post collection state updates.
1102   MetaspaceGC::compute_new_size();
1103 }
1104 
1105 void G1CollectedHeap::abort_refinement() {
1106   if (_hot_card_cache->use_cache()) {
1107     _hot_card_cache->reset_hot_cache();
1108   }
1109 
1110   // Discard all remembered set updates.
1111   JavaThread::dirty_card_queue_set().abandon_logs();
1112   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1113 }
1114 
1115 void G1CollectedHeap::verify_after_full_collection() {
1116   check_gc_time_stamps();
1117   _hrm.verify_optional();
1118   _verifier->verify_region_sets_optional();
1119   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1120   // Clear the previous marking bitmap, if needed for bitmap verification.
1121   // Note we cannot do this when we clear the next marking bitmap in
1122   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1123   // objects marked during a full GC against the previous bitmap.
1124   // But we need to clear it before calling check_bitmaps below since
1125   // the full GC has compacted objects and updated TAMS but not updated
1126   // the prev bitmap.
1127   if (G1VerifyBitmaps) {
1128     GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1129     _cm->clear_prev_bitmap(workers());
1130   }
1131   _verifier->check_bitmaps("Full GC End");
1132 
1133   // At this point there should be no regions in the
1134   // entire heap tagged as young.
1135   assert(check_young_list_empty(), "young list should be empty at this point");
1136 
1137   // Note: since we've just done a full GC, concurrent
1138   // marking is no longer active. Therefore we need not
1139   // re-enable reference discovery for the CM ref processor.
1140   // That will be done at the start of the next marking cycle.
1141   // We also know that the STW processor should no longer
1142   // discover any new references.
1143   assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1144   assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1145   ref_processor_stw()->verify_no_references_recorded();
1146   ref_processor_cm()->verify_no_references_recorded();
1147 }
1148 
1149 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1150   // Post collection logging.
1151   // We should do this after we potentially resize the heap so
1152   // that all the COMMIT / UNCOMMIT events are generated before
1153   // the compaction events.
1154   print_hrm_post_compaction();
1155   heap_transition->print();
1156   print_heap_after_gc();
1157   print_heap_regions();
1158 #ifdef TRACESPINNING
1159   ParallelTaskTerminator::print_termination_counts();
1160 #endif
1161 }
1162 
1163 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1164                                          bool clear_all_soft_refs) {
1165   assert_at_safepoint(true /* should_be_vm_thread */);
1166 
1167   if (GCLocker::check_active_before_gc()) {
1168     // Full GC was not completed.
1169     return false;
1170   }
1171 
1172   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1173       soft_ref_policy()->should_clear_all_soft_refs();
1174 
1175   G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1176   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1177 
1178   collector.prepare_collection();
1179   collector.collect();
1180   collector.complete_collection();
1181 
1182   // Full collection was successfully completed.
1183   return true;
1184 }
1185 
1186 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1187   // Currently, there is no facility in the do_full_collection(bool) API to notify
1188   // the caller that the collection did not succeed (e.g., because it was locked
1189   // out by the GC locker). So, right now, we'll ignore the return value.
1190   bool dummy = do_full_collection(true,                /* explicit_gc */
1191                                   clear_all_soft_refs);
1192 }
1193 
1194 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1195   // Capacity, free and used after the GC counted as full regions to
1196   // include the waste in the following calculations.
1197   const size_t capacity_after_gc = capacity();
1198   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1199 
1200   // This is enforced in arguments.cpp.
1201   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1202          "otherwise the code below doesn't make sense");
1203 
1204   // We don't have floating point command-line arguments
1205   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1206   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1207   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1208   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1209 
1210   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1211   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1212 
1213   // We have to be careful here as these two calculations can overflow
1214   // 32-bit size_t's.
1215   double used_after_gc_d = (double) used_after_gc;
1216   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1217   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1218 
1219   // Let's make sure that they are both under the max heap size, which
1220   // by default will make them fit into a size_t.
1221   double desired_capacity_upper_bound = (double) max_heap_size;
1222   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1223                                     desired_capacity_upper_bound);
1224   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1225                                     desired_capacity_upper_bound);
1226 
1227   // We can now safely turn them into size_t's.
1228   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1229   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1230 
1231   // This assert only makes sense here, before we adjust them
1232   // with respect to the min and max heap size.
1233   assert(minimum_desired_capacity <= maximum_desired_capacity,
1234          "minimum_desired_capacity = " SIZE_FORMAT ", "
1235          "maximum_desired_capacity = " SIZE_FORMAT,
1236          minimum_desired_capacity, maximum_desired_capacity);
1237 
1238   // Should not be greater than the heap max size. No need to adjust
1239   // it with respect to the heap min size as it's a lower bound (i.e.,
1240   // we'll try to make the capacity larger than it, not smaller).
1241   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1242   // Should not be less than the heap min size. No need to adjust it
1243   // with respect to the heap max size as it's an upper bound (i.e.,
1244   // we'll try to make the capacity smaller than it, not greater).
1245   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1246 
1247   if (capacity_after_gc < minimum_desired_capacity) {
1248     // Don't expand unless it's significant
1249     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1250 
1251     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1252                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1253                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1254                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1255 
1256     expand(expand_bytes, _workers);
1257 
1258     // No expansion, now see if we want to shrink
1259   } else if (capacity_after_gc > maximum_desired_capacity) {
1260     // Capacity too large, compute shrinking size
1261     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1262 
1263     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1264                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1265                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1266                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1267 
1268     shrink(shrink_bytes);
1269   }
1270 }
1271 
1272 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1273                                                             AllocationContext_t context,
1274                                                             bool do_gc,
1275                                                             bool clear_all_soft_refs,
1276                                                             bool expect_null_mutator_alloc_region,
1277                                                             bool* gc_succeeded) {
1278   *gc_succeeded = true;
1279   // Let's attempt the allocation first.
1280   HeapWord* result =
1281     attempt_allocation_at_safepoint(word_size,
1282                                     context,
1283                                     expect_null_mutator_alloc_region);
1284   if (result != NULL) {
1285     return result;
1286   }
1287 
1288   // In a G1 heap, we're supposed to keep allocation from failing by
1289   // incremental pauses.  Therefore, at least for now, we'll favor
1290   // expansion over collection.  (This might change in the future if we can
1291   // do something smarter than full collection to satisfy a failed alloc.)
1292   result = expand_and_allocate(word_size, context);
1293   if (result != NULL) {
1294     return result;
1295   }
1296 
1297   if (do_gc) {
1298     // Expansion didn't work, we'll try to do a Full GC.
1299     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1300                                        clear_all_soft_refs);
1301   }
1302 
1303   return NULL;
1304 }
1305 
1306 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1307                                                      AllocationContext_t context,
1308                                                      bool* succeeded) {
1309   assert_at_safepoint(true /* should_be_vm_thread */);
1310 
1311   // Attempts to allocate followed by Full GC.
1312   HeapWord* result =
1313     satisfy_failed_allocation_helper(word_size,
1314                                      context,
1315                                      true,  /* do_gc */
1316                                      false, /* clear_all_soft_refs */
1317                                      false, /* expect_null_mutator_alloc_region */
1318                                      succeeded);
1319 
1320   if (result != NULL || !*succeeded) {
1321     return result;
1322   }
1323 
1324   // Attempts to allocate followed by Full GC that will collect all soft references.
1325   result = satisfy_failed_allocation_helper(word_size,
1326                                             context,
1327                                             true, /* do_gc */
1328                                             true, /* clear_all_soft_refs */
1329                                             true, /* expect_null_mutator_alloc_region */
1330                                             succeeded);
1331 
1332   if (result != NULL || !*succeeded) {
1333     return result;
1334   }
1335 
1336   // Attempts to allocate, no GC
1337   result = satisfy_failed_allocation_helper(word_size,
1338                                             context,
1339                                             false, /* do_gc */
1340                                             false, /* clear_all_soft_refs */
1341                                             true,  /* expect_null_mutator_alloc_region */
1342                                             succeeded);
1343 
1344   if (result != NULL) {
1345     return result;
1346   }
1347 
1348   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1349          "Flag should have been handled and cleared prior to this point");
1350 
1351   // What else?  We might try synchronous finalization later.  If the total
1352   // space available is large enough for the allocation, then a more
1353   // complete compaction phase than we've tried so far might be
1354   // appropriate.
1355   return NULL;
1356 }
1357 
1358 // Attempting to expand the heap sufficiently
1359 // to support an allocation of the given "word_size".  If
1360 // successful, perform the allocation and return the address of the
1361 // allocated block, or else "NULL".
1362 
1363 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1364   assert_at_safepoint(true /* should_be_vm_thread */);
1365 
1366   _verifier->verify_region_sets_optional();
1367 
1368   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1369   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1370                             word_size * HeapWordSize);
1371 
1372 
1373   if (expand(expand_bytes, _workers)) {
1374     _hrm.verify_optional();
1375     _verifier->verify_region_sets_optional();
1376     return attempt_allocation_at_safepoint(word_size,
1377                                            context,
1378                                            false /* expect_null_mutator_alloc_region */);
1379   }
1380   return NULL;
1381 }
1382 
1383 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1384   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1385   aligned_expand_bytes = align_up(aligned_expand_bytes,
1386                                        HeapRegion::GrainBytes);
1387 
1388   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1389                             expand_bytes, aligned_expand_bytes);
1390 
1391   if (is_maximal_no_gc()) {
1392     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1393     return false;
1394   }
1395 
1396   double expand_heap_start_time_sec = os::elapsedTime();
1397   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1398   assert(regions_to_expand > 0, "Must expand by at least one region");
1399 
1400   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1401   if (expand_time_ms != NULL) {
1402     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1403   }
1404 
1405   if (expanded_by > 0) {
1406     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1407     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1408     g1_policy()->record_new_heap_size(num_regions());
1409   } else {
1410     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1411 
1412     // The expansion of the virtual storage space was unsuccessful.
1413     // Let's see if it was because we ran out of swap.
1414     if (G1ExitOnExpansionFailure &&
1415         _hrm.available() >= regions_to_expand) {
1416       // We had head room...
1417       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1418     }
1419   }
1420   return regions_to_expand > 0;
1421 }
1422 
1423 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1424   size_t aligned_shrink_bytes =
1425     ReservedSpace::page_align_size_down(shrink_bytes);
1426   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1427                                          HeapRegion::GrainBytes);
1428   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1429 
1430   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1431   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1432 
1433 
1434   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",
1435                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1436   if (num_regions_removed > 0) {
1437     g1_policy()->record_new_heap_size(num_regions());
1438   } else {
1439     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1440   }
1441 }
1442 
1443 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1444   _verifier->verify_region_sets_optional();
1445 
1446   // We should only reach here at the end of a Full GC which means we
1447   // should not not be holding to any GC alloc regions. The method
1448   // below will make sure of that and do any remaining clean up.
1449   _allocator->abandon_gc_alloc_regions();
1450 
1451   // Instead of tearing down / rebuilding the free lists here, we
1452   // could instead use the remove_all_pending() method on free_list to
1453   // remove only the ones that we need to remove.
1454   tear_down_region_sets(true /* free_list_only */);
1455   shrink_helper(shrink_bytes);
1456   rebuild_region_sets(true /* free_list_only */);
1457 
1458   _hrm.verify_optional();
1459   _verifier->verify_region_sets_optional();
1460 }
1461 
1462 // Public methods.
1463 
1464 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1465   CollectedHeap(),
1466   _young_gen_sampling_thread(NULL),
1467   _collector_policy(collector_policy),
1468   _soft_ref_policy(),
1469   _card_table(NULL),
1470   _memory_manager("G1 Young Generation", "end of minor GC"),
1471   _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1472   _eden_pool(NULL),
1473   _survivor_pool(NULL),
1474   _old_pool(NULL),
1475   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1476   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1477   _g1_policy(create_g1_policy(_gc_timer_stw)),
1478   _collection_set(this, _g1_policy),
1479   _dirty_card_queue_set(false),
1480   _is_alive_closure_cm(this),
1481   _is_alive_closure_stw(this),
1482   _ref_processor_cm(NULL),
1483   _ref_processor_stw(NULL),
1484   _bot(NULL),
1485   _hot_card_cache(NULL),
1486   _g1_rem_set(NULL),
1487   _cr(NULL),
1488   _g1mm(NULL),
1489   _preserved_marks_set(true /* in_c_heap */),
1490   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1491   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1492   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1493   _humongous_reclaim_candidates(),
1494   _has_humongous_reclaim_candidates(false),
1495   _archive_allocator(NULL),
1496   _free_regions_coming(false),
1497   _gc_time_stamp(0),
1498   _summary_bytes_used(0),
1499   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1500   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1501   _expand_heap_after_alloc_failure(true),
1502   _old_marking_cycles_started(0),
1503   _old_marking_cycles_completed(0),
1504   _in_cset_fast_test() {
1505 
1506   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1507                           /* are_GC_task_threads */true,
1508                           /* are_ConcurrentGC_threads */false);
1509   _workers->initialize_workers();
1510   _verifier = new G1HeapVerifier(this);
1511 
1512   _allocator = G1Allocator::create_allocator(this);
1513 
1514   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1515 
1516   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1517 
1518   // Override the default _filler_array_max_size so that no humongous filler
1519   // objects are created.
1520   _filler_array_max_size = _humongous_object_threshold_in_words;
1521 
1522   uint n_queues = ParallelGCThreads;
1523   _task_queues = new RefToScanQueueSet(n_queues);
1524 
1525   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1526 
1527   for (uint i = 0; i < n_queues; i++) {
1528     RefToScanQueue* q = new RefToScanQueue();
1529     q->initialize();
1530     _task_queues->register_queue(i, q);
1531     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1532   }
1533 
1534   // Initialize the G1EvacuationFailureALot counters and flags.
1535   NOT_PRODUCT(reset_evacuation_should_fail();)
1536 
1537   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1538 }
1539 
1540 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1541                                                                  size_t size,
1542                                                                  size_t translation_factor) {
1543   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1544   // Allocate a new reserved space, preferring to use large pages.
1545   ReservedSpace rs(size, preferred_page_size);
1546   G1RegionToSpaceMapper* result  =
1547     G1RegionToSpaceMapper::create_mapper(rs,
1548                                          size,
1549                                          rs.alignment(),
1550                                          HeapRegion::GrainBytes,
1551                                          translation_factor,
1552                                          mtGC);
1553 
1554   os::trace_page_sizes_for_requested_size(description,
1555                                           size,
1556                                           preferred_page_size,
1557                                           rs.alignment(),
1558                                           rs.base(),
1559                                           rs.size());
1560 
1561   return result;
1562 }
1563 
1564 jint G1CollectedHeap::initialize_concurrent_refinement() {
1565   jint ecode = JNI_OK;
1566   _cr = G1ConcurrentRefine::create(&ecode);
1567   return ecode;
1568 }
1569 
1570 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1571   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1572   if (_young_gen_sampling_thread->osthread() == NULL) {
1573     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1574     return JNI_ENOMEM;
1575   }
1576   return JNI_OK;
1577 }
1578 
1579 jint G1CollectedHeap::initialize() {
1580   os::enable_vtime();
1581 
1582   // Necessary to satisfy locking discipline assertions.
1583 
1584   MutexLocker x(Heap_lock);
1585 
1586   // While there are no constraints in the GC code that HeapWordSize
1587   // be any particular value, there are multiple other areas in the
1588   // system which believe this to be true (e.g. oop->object_size in some
1589   // cases incorrectly returns the size in wordSize units rather than
1590   // HeapWordSize).
1591   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1592 
1593   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1594   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1595   size_t heap_alignment = collector_policy()->heap_alignment();
1596 
1597   // Ensure that the sizes are properly aligned.
1598   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1599   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1600   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1601 
1602   // Reserve the maximum.
1603 
1604   // When compressed oops are enabled, the preferred heap base
1605   // is calculated by subtracting the requested size from the
1606   // 32Gb boundary and using the result as the base address for
1607   // heap reservation. If the requested size is not aligned to
1608   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1609   // into the ReservedHeapSpace constructor) then the actual
1610   // base of the reserved heap may end up differing from the
1611   // address that was requested (i.e. the preferred heap base).
1612   // If this happens then we could end up using a non-optimal
1613   // compressed oops mode.
1614 
1615   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1616                                                  heap_alignment);
1617 
1618   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1619 
1620   // Create the barrier set for the entire reserved region.
1621   G1CardTable* ct = new G1CardTable(reserved_region());
1622   ct->initialize();
1623   G1SATBCardTableLoggingModRefBS* bs = new G1SATBCardTableLoggingModRefBS(ct);
1624   bs->initialize();
1625   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1626   set_barrier_set(bs);
1627   _card_table = ct;
1628 
1629   // Create the hot card cache.
1630   _hot_card_cache = new G1HotCardCache(this);
1631 
1632   // Carve out the G1 part of the heap.
1633   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1634   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1635   G1RegionToSpaceMapper* heap_storage =
1636     G1RegionToSpaceMapper::create_mapper(g1_rs,
1637                                          g1_rs.size(),
1638                                          page_size,
1639                                          HeapRegion::GrainBytes,
1640                                          1,
1641                                          mtJavaHeap);
1642   os::trace_page_sizes("Heap",
1643                        collector_policy()->min_heap_byte_size(),
1644                        max_byte_size,
1645                        page_size,
1646                        heap_rs.base(),
1647                        heap_rs.size());
1648   heap_storage->set_mapping_changed_listener(&_listener);
1649 
1650   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1651   G1RegionToSpaceMapper* bot_storage =
1652     create_aux_memory_mapper("Block Offset Table",
1653                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1654                              G1BlockOffsetTable::heap_map_factor());
1655 
1656   G1RegionToSpaceMapper* cardtable_storage =
1657     create_aux_memory_mapper("Card Table",
1658                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1659                              G1CardTable::heap_map_factor());
1660 
1661   G1RegionToSpaceMapper* card_counts_storage =
1662     create_aux_memory_mapper("Card Counts Table",
1663                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1664                              G1CardCounts::heap_map_factor());
1665 
1666   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1667   G1RegionToSpaceMapper* prev_bitmap_storage =
1668     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1669   G1RegionToSpaceMapper* next_bitmap_storage =
1670     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1671 
1672   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1673   _card_table->initialize(cardtable_storage);
1674   // Do later initialization work for concurrent refinement.
1675   _hot_card_cache->initialize(card_counts_storage);
1676 
1677   // 6843694 - ensure that the maximum region index can fit
1678   // in the remembered set structures.
1679   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1680   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1681 
1682   // Also create a G1 rem set.
1683   _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1684   _g1_rem_set->initialize(max_capacity(), max_regions());
1685 
1686   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1687   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1688   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1689             "too many cards per region");
1690 
1691   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1692 
1693   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1694 
1695   {
1696     HeapWord* start = _hrm.reserved().start();
1697     HeapWord* end = _hrm.reserved().end();
1698     size_t granularity = HeapRegion::GrainBytes;
1699 
1700     _in_cset_fast_test.initialize(start, end, granularity);
1701     _humongous_reclaim_candidates.initialize(start, end, granularity);
1702   }
1703 
1704   // Create the G1ConcurrentMark data structure and thread.
1705   // (Must do this late, so that "max_regions" is defined.)
1706   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1707   if (_cm == NULL || !_cm->completed_initialization()) {
1708     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1709     return JNI_ENOMEM;
1710   }
1711   _cmThread = _cm->cm_thread();
1712 
1713   // Now expand into the initial heap size.
1714   if (!expand(init_byte_size, _workers)) {
1715     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1716     return JNI_ENOMEM;
1717   }
1718 
1719   // Perform any initialization actions delegated to the policy.
1720   g1_policy()->init(this, &_collection_set);
1721 
1722   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1723                                                SATB_Q_FL_lock,
1724                                                G1SATBProcessCompletedThreshold,
1725                                                Shared_SATB_Q_lock);
1726 
1727   jint ecode = initialize_concurrent_refinement();
1728   if (ecode != JNI_OK) {
1729     return ecode;
1730   }
1731 
1732   ecode = initialize_young_gen_sampling_thread();
1733   if (ecode != JNI_OK) {
1734     return ecode;
1735   }
1736 
1737   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1738                                                 DirtyCardQ_FL_lock,
1739                                                 (int)concurrent_refine()->yellow_zone(),
1740                                                 (int)concurrent_refine()->red_zone(),
1741                                                 Shared_DirtyCardQ_lock,
1742                                                 NULL,  // fl_owner
1743                                                 true); // init_free_ids
1744 
1745   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1746                                     DirtyCardQ_FL_lock,
1747                                     -1, // never trigger processing
1748                                     -1, // no limit on length
1749                                     Shared_DirtyCardQ_lock,
1750                                     &JavaThread::dirty_card_queue_set());
1751 
1752   // Here we allocate the dummy HeapRegion that is required by the
1753   // G1AllocRegion class.
1754   HeapRegion* dummy_region = _hrm.get_dummy_region();
1755 
1756   // We'll re-use the same region whether the alloc region will
1757   // require BOT updates or not and, if it doesn't, then a non-young
1758   // region will complain that it cannot support allocations without
1759   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1760   dummy_region->set_eden();
1761   // Make sure it's full.
1762   dummy_region->set_top(dummy_region->end());
1763   G1AllocRegion::setup(this, dummy_region);
1764 
1765   _allocator->init_mutator_alloc_region();
1766 
1767   // Do create of the monitoring and management support so that
1768   // values in the heap have been properly initialized.
1769   _g1mm = new G1MonitoringSupport(this);
1770 
1771   G1StringDedup::initialize();
1772 
1773   _preserved_marks_set.init(ParallelGCThreads);
1774 
1775   _collection_set.initialize(max_regions());
1776 
1777   return JNI_OK;
1778 }
1779 
1780 void G1CollectedHeap::initialize_serviceability() {
1781   _eden_pool = new G1EdenPool(this);
1782   _survivor_pool = new G1SurvivorPool(this);
1783   _old_pool = new G1OldGenPool(this);
1784 
1785   _full_gc_memory_manager.add_pool(_eden_pool);
1786   _full_gc_memory_manager.add_pool(_survivor_pool);
1787   _full_gc_memory_manager.add_pool(_old_pool);
1788 
1789   _memory_manager.add_pool(_eden_pool);
1790   _memory_manager.add_pool(_survivor_pool);
1791 
1792 }
1793 
1794 void G1CollectedHeap::stop() {
1795   // Stop all concurrent threads. We do this to make sure these threads
1796   // do not continue to execute and access resources (e.g. logging)
1797   // that are destroyed during shutdown.
1798   _cr->stop();
1799   _young_gen_sampling_thread->stop();
1800   _cmThread->stop();
1801   if (G1StringDedup::is_enabled()) {
1802     G1StringDedup::stop();
1803   }
1804 }
1805 
1806 void G1CollectedHeap::safepoint_synchronize_begin() {
1807   SuspendibleThreadSet::synchronize();
1808 }
1809 
1810 void G1CollectedHeap::safepoint_synchronize_end() {
1811   SuspendibleThreadSet::desynchronize();
1812 }
1813 
1814 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1815   return HeapRegion::max_region_size();
1816 }
1817 
1818 void G1CollectedHeap::post_initialize() {
1819   CollectedHeap::post_initialize();
1820   ref_processing_init();
1821 }
1822 
1823 void G1CollectedHeap::ref_processing_init() {
1824   // Reference processing in G1 currently works as follows:
1825   //
1826   // * There are two reference processor instances. One is
1827   //   used to record and process discovered references
1828   //   during concurrent marking; the other is used to
1829   //   record and process references during STW pauses
1830   //   (both full and incremental).
1831   // * Both ref processors need to 'span' the entire heap as
1832   //   the regions in the collection set may be dotted around.
1833   //
1834   // * For the concurrent marking ref processor:
1835   //   * Reference discovery is enabled at initial marking.
1836   //   * Reference discovery is disabled and the discovered
1837   //     references processed etc during remarking.
1838   //   * Reference discovery is MT (see below).
1839   //   * Reference discovery requires a barrier (see below).
1840   //   * Reference processing may or may not be MT
1841   //     (depending on the value of ParallelRefProcEnabled
1842   //     and ParallelGCThreads).
1843   //   * A full GC disables reference discovery by the CM
1844   //     ref processor and abandons any entries on it's
1845   //     discovered lists.
1846   //
1847   // * For the STW processor:
1848   //   * Non MT discovery is enabled at the start of a full GC.
1849   //   * Processing and enqueueing during a full GC is non-MT.
1850   //   * During a full GC, references are processed after marking.
1851   //
1852   //   * Discovery (may or may not be MT) is enabled at the start
1853   //     of an incremental evacuation pause.
1854   //   * References are processed near the end of a STW evacuation pause.
1855   //   * For both types of GC:
1856   //     * Discovery is atomic - i.e. not concurrent.
1857   //     * Reference discovery will not need a barrier.
1858 
1859   MemRegion mr = reserved_region();
1860 
1861   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1862 
1863   // Concurrent Mark ref processor
1864   _ref_processor_cm =
1865     new ReferenceProcessor(mr,    // span
1866                            mt_processing,
1867                                 // mt processing
1868                            ParallelGCThreads,
1869                                 // degree of mt processing
1870                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1871                                 // mt discovery
1872                            MAX2(ParallelGCThreads, ConcGCThreads),
1873                                 // degree of mt discovery
1874                            false,
1875                                 // Reference discovery is not atomic
1876                            &_is_alive_closure_cm);
1877                                 // is alive closure
1878                                 // (for efficiency/performance)
1879 
1880   // STW ref processor
1881   _ref_processor_stw =
1882     new ReferenceProcessor(mr,    // span
1883                            mt_processing,
1884                                 // mt processing
1885                            ParallelGCThreads,
1886                                 // degree of mt processing
1887                            (ParallelGCThreads > 1),
1888                                 // mt discovery
1889                            ParallelGCThreads,
1890                                 // degree of mt discovery
1891                            true,
1892                                 // Reference discovery is atomic
1893                            &_is_alive_closure_stw);
1894                                 // is alive closure
1895                                 // (for efficiency/performance)
1896 }
1897 
1898 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1899   return _collector_policy;
1900 }
1901 
1902 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1903   return &_soft_ref_policy;
1904 }
1905 
1906 size_t G1CollectedHeap::capacity() const {
1907   return _hrm.length() * HeapRegion::GrainBytes;
1908 }
1909 
1910 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1911   return _hrm.total_free_bytes();
1912 }
1913 
1914 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1915   hr->reset_gc_time_stamp();
1916 }
1917 
1918 #ifndef PRODUCT
1919 
1920 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1921 private:
1922   unsigned _gc_time_stamp;
1923   bool _failures;
1924 
1925 public:
1926   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1927     _gc_time_stamp(gc_time_stamp), _failures(false) { }
1928 
1929   virtual bool do_heap_region(HeapRegion* hr) {
1930     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1931     if (_gc_time_stamp != region_gc_time_stamp) {
1932       log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1933                             region_gc_time_stamp, _gc_time_stamp);
1934       _failures = true;
1935     }
1936     return false;
1937   }
1938 
1939   bool failures() { return _failures; }
1940 };
1941 
1942 void G1CollectedHeap::check_gc_time_stamps() {
1943   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1944   heap_region_iterate(&cl);
1945   guarantee(!cl.failures(), "all GC time stamps should have been reset");
1946 }
1947 #endif // PRODUCT
1948 
1949 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1950   _hot_card_cache->drain(cl, worker_i);
1951 }
1952 
1953 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1954   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1955   size_t n_completed_buffers = 0;
1956   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1957     n_completed_buffers++;
1958   }
1959   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1960   dcqs.clear_n_completed_buffers();
1961   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1962 }
1963 
1964 // Computes the sum of the storage used by the various regions.
1965 size_t G1CollectedHeap::used() const {
1966   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1967   if (_archive_allocator != NULL) {
1968     result += _archive_allocator->used();
1969   }
1970   return result;
1971 }
1972 
1973 size_t G1CollectedHeap::used_unlocked() const {
1974   return _summary_bytes_used;
1975 }
1976 
1977 class SumUsedClosure: public HeapRegionClosure {
1978   size_t _used;
1979 public:
1980   SumUsedClosure() : _used(0) {}
1981   bool do_heap_region(HeapRegion* r) {
1982     _used += r->used();
1983     return false;
1984   }
1985   size_t result() { return _used; }
1986 };
1987 
1988 size_t G1CollectedHeap::recalculate_used() const {
1989   double recalculate_used_start = os::elapsedTime();
1990 
1991   SumUsedClosure blk;
1992   heap_region_iterate(&blk);
1993 
1994   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1995   return blk.result();
1996 }
1997 
1998 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1999   switch (cause) {
2000     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2001     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2002     case GCCause::_wb_conc_mark:                        return true;
2003     default :                                           return false;
2004   }
2005 }
2006 
2007 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2008   switch (cause) {
2009     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2010     case GCCause::_g1_humongous_allocation: return true;
2011     default:                                return is_user_requested_concurrent_full_gc(cause);
2012   }
2013 }
2014 
2015 #ifndef PRODUCT
2016 void G1CollectedHeap::allocate_dummy_regions() {
2017   // Let's fill up most of the region
2018   size_t word_size = HeapRegion::GrainWords - 1024;
2019   // And as a result the region we'll allocate will be humongous.
2020   guarantee(is_humongous(word_size), "sanity");
2021 
2022   // _filler_array_max_size is set to humongous object threshold
2023   // but temporarily change it to use CollectedHeap::fill_with_object().
2024   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2025 
2026   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2027     // Let's use the existing mechanism for the allocation
2028     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2029                                                  AllocationContext::system());
2030     if (dummy_obj != NULL) {
2031       MemRegion mr(dummy_obj, word_size);
2032       CollectedHeap::fill_with_object(mr);
2033     } else {
2034       // If we can't allocate once, we probably cannot allocate
2035       // again. Let's get out of the loop.
2036       break;
2037     }
2038   }
2039 }
2040 #endif // !PRODUCT
2041 
2042 void G1CollectedHeap::increment_old_marking_cycles_started() {
2043   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2044          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2045          "Wrong marking cycle count (started: %d, completed: %d)",
2046          _old_marking_cycles_started, _old_marking_cycles_completed);
2047 
2048   _old_marking_cycles_started++;
2049 }
2050 
2051 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2052   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2053 
2054   // We assume that if concurrent == true, then the caller is a
2055   // concurrent thread that was joined the Suspendible Thread
2056   // Set. If there's ever a cheap way to check this, we should add an
2057   // assert here.
2058 
2059   // Given that this method is called at the end of a Full GC or of a
2060   // concurrent cycle, and those can be nested (i.e., a Full GC can
2061   // interrupt a concurrent cycle), the number of full collections
2062   // completed should be either one (in the case where there was no
2063   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2064   // behind the number of full collections started.
2065 
2066   // This is the case for the inner caller, i.e. a Full GC.
2067   assert(concurrent ||
2068          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2069          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2070          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2071          "is inconsistent with _old_marking_cycles_completed = %u",
2072          _old_marking_cycles_started, _old_marking_cycles_completed);
2073 
2074   // This is the case for the outer caller, i.e. the concurrent cycle.
2075   assert(!concurrent ||
2076          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2077          "for outer caller (concurrent cycle): "
2078          "_old_marking_cycles_started = %u "
2079          "is inconsistent with _old_marking_cycles_completed = %u",
2080          _old_marking_cycles_started, _old_marking_cycles_completed);
2081 
2082   _old_marking_cycles_completed += 1;
2083 
2084   // We need to clear the "in_progress" flag in the CM thread before
2085   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2086   // is set) so that if a waiter requests another System.gc() it doesn't
2087   // incorrectly see that a marking cycle is still in progress.
2088   if (concurrent) {
2089     _cmThread->set_idle();
2090   }
2091 
2092   // This notify_all() will ensure that a thread that called
2093   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2094   // and it's waiting for a full GC to finish will be woken up. It is
2095   // waiting in VM_G1CollectForAllocation::doit_epilogue().
2096   FullGCCount_lock->notify_all();
2097 }
2098 
2099 void G1CollectedHeap::collect(GCCause::Cause cause) {
2100   assert_heap_not_locked();
2101 
2102   uint gc_count_before;
2103   uint old_marking_count_before;
2104   uint full_gc_count_before;
2105   bool retry_gc;
2106 
2107   do {
2108     retry_gc = false;
2109 
2110     {
2111       MutexLocker ml(Heap_lock);
2112 
2113       // Read the GC count while holding the Heap_lock
2114       gc_count_before = total_collections();
2115       full_gc_count_before = total_full_collections();
2116       old_marking_count_before = _old_marking_cycles_started;
2117     }
2118 
2119     if (should_do_concurrent_full_gc(cause)) {
2120       // Schedule an initial-mark evacuation pause that will start a
2121       // concurrent cycle. We're setting word_size to 0 which means that
2122       // we are not requesting a post-GC allocation.
2123       VM_G1CollectForAllocation op(0,     /* word_size */
2124                                    gc_count_before,
2125                                    cause,
2126                                    true,  /* should_initiate_conc_mark */
2127                                    g1_policy()->max_pause_time_ms(),
2128                                    AllocationContext::current());
2129       VMThread::execute(&op);
2130       if (!op.pause_succeeded()) {
2131         if (old_marking_count_before == _old_marking_cycles_started) {
2132           retry_gc = op.should_retry_gc();
2133         } else {
2134           // A Full GC happened while we were trying to schedule the
2135           // initial-mark GC. No point in starting a new cycle given
2136           // that the whole heap was collected anyway.
2137         }
2138 
2139         if (retry_gc) {
2140           if (GCLocker::is_active_and_needs_gc()) {
2141             GCLocker::stall_until_clear();
2142           }
2143         }
2144       }
2145     } else {
2146       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2147           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2148 
2149         // Schedule a standard evacuation pause. We're setting word_size
2150         // to 0 which means that we are not requesting a post-GC allocation.
2151         VM_G1CollectForAllocation op(0,     /* word_size */
2152                                      gc_count_before,
2153                                      cause,
2154                                      false, /* should_initiate_conc_mark */
2155                                      g1_policy()->max_pause_time_ms(),
2156                                      AllocationContext::current());
2157         VMThread::execute(&op);
2158       } else {
2159         // Schedule a Full GC.
2160         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2161         VMThread::execute(&op);
2162       }
2163     }
2164   } while (retry_gc);
2165 }
2166 
2167 bool G1CollectedHeap::is_in(const void* p) const {
2168   if (_hrm.reserved().contains(p)) {
2169     // Given that we know that p is in the reserved space,
2170     // heap_region_containing() should successfully
2171     // return the containing region.
2172     HeapRegion* hr = heap_region_containing(p);
2173     return hr->is_in(p);
2174   } else {
2175     return false;
2176   }
2177 }
2178 
2179 #ifdef ASSERT
2180 bool G1CollectedHeap::is_in_exact(const void* p) const {
2181   bool contains = reserved_region().contains(p);
2182   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2183   if (contains && available) {
2184     return true;
2185   } else {
2186     return false;
2187   }
2188 }
2189 #endif
2190 
2191 // Iteration functions.
2192 
2193 // Iterates an ObjectClosure over all objects within a HeapRegion.
2194 
2195 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2196   ObjectClosure* _cl;
2197 public:
2198   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2199   bool do_heap_region(HeapRegion* r) {
2200     if (!r->is_continues_humongous()) {
2201       r->object_iterate(_cl);
2202     }
2203     return false;
2204   }
2205 };
2206 
2207 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2208   IterateObjectClosureRegionClosure blk(cl);
2209   heap_region_iterate(&blk);
2210 }
2211 
2212 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2213   _hrm.iterate(cl);
2214 }
2215 
2216 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2217                                                                  HeapRegionClaimer *hrclaimer,
2218                                                                  uint worker_id) const {
2219   _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2220 }
2221 
2222 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2223                                                          HeapRegionClaimer *hrclaimer) const {
2224   _hrm.par_iterate(cl, hrclaimer, 0);
2225 }
2226 
2227 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2228   _collection_set.iterate(cl);
2229 }
2230 
2231 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2232   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2233 }
2234 
2235 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2236   HeapRegion* hr = heap_region_containing(addr);
2237   return hr->block_start(addr);
2238 }
2239 
2240 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2241   HeapRegion* hr = heap_region_containing(addr);
2242   return hr->block_size(addr);
2243 }
2244 
2245 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2246   HeapRegion* hr = heap_region_containing(addr);
2247   return hr->block_is_obj(addr);
2248 }
2249 
2250 bool G1CollectedHeap::supports_tlab_allocation() const {
2251   return true;
2252 }
2253 
2254 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2255   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2256 }
2257 
2258 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2259   return _eden.length() * HeapRegion::GrainBytes;
2260 }
2261 
2262 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2263 // must be equal to the humongous object limit.
2264 size_t G1CollectedHeap::max_tlab_size() const {
2265   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2266 }
2267 
2268 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2269   AllocationContext_t context = AllocationContext::current();
2270   return _allocator->unsafe_max_tlab_alloc(context);
2271 }
2272 
2273 size_t G1CollectedHeap::max_capacity() const {
2274   return _hrm.reserved().byte_size();
2275 }
2276 
2277 jlong G1CollectedHeap::millis_since_last_gc() {
2278   // See the notes in GenCollectedHeap::millis_since_last_gc()
2279   // for more information about the implementation.
2280   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2281     _g1_policy->collection_pause_end_millis();
2282   if (ret_val < 0) {
2283     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2284       ". returning zero instead.", ret_val);
2285     return 0;
2286   }
2287   return ret_val;
2288 }
2289 
2290 void G1CollectedHeap::prepare_for_verify() {
2291   _verifier->prepare_for_verify();
2292 }
2293 
2294 void G1CollectedHeap::verify(VerifyOption vo) {
2295   _verifier->verify(vo);
2296 }
2297 
2298 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2299   return true;
2300 }
2301 
2302 const char* const* G1CollectedHeap::concurrent_phases() const {
2303   return _cmThread->concurrent_phases();
2304 }
2305 
2306 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2307   return _cmThread->request_concurrent_phase(phase);
2308 }
2309 
2310 class PrintRegionClosure: public HeapRegionClosure {
2311   outputStream* _st;
2312 public:
2313   PrintRegionClosure(outputStream* st) : _st(st) {}
2314   bool do_heap_region(HeapRegion* r) {
2315     r->print_on(_st);
2316     return false;
2317   }
2318 };
2319 
2320 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2321                                        const HeapRegion* hr,
2322                                        const VerifyOption vo) const {
2323   switch (vo) {
2324   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2325   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2326   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2327   default:                            ShouldNotReachHere();
2328   }
2329   return false; // keep some compilers happy
2330 }
2331 
2332 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2333                                        const VerifyOption vo) const {
2334   switch (vo) {
2335   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2336   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2337   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2338   default:                            ShouldNotReachHere();
2339   }
2340   return false; // keep some compilers happy
2341 }
2342 
2343 void G1CollectedHeap::print_heap_regions() const {
2344   LogTarget(Trace, gc, heap, region) lt;
2345   if (lt.is_enabled()) {
2346     LogStream ls(lt);
2347     print_regions_on(&ls);
2348   }
2349 }
2350 
2351 void G1CollectedHeap::print_on(outputStream* st) const {
2352   st->print(" %-20s", "garbage-first heap");
2353   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2354             capacity()/K, used_unlocked()/K);
2355   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2356             p2i(_hrm.reserved().start()),
2357             p2i(_hrm.reserved().end()));
2358   st->cr();
2359   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2360   uint young_regions = young_regions_count();
2361   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2362             (size_t) young_regions * HeapRegion::GrainBytes / K);
2363   uint survivor_regions = survivor_regions_count();
2364   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2365             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2366   st->cr();
2367   MetaspaceAux::print_on(st);
2368 }
2369 
2370 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2371   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2372                "HS=humongous(starts), HC=humongous(continues), "
2373                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2374                "AC=allocation context, "
2375                "TAMS=top-at-mark-start (previous, next)");
2376   PrintRegionClosure blk(st);
2377   heap_region_iterate(&blk);
2378 }
2379 
2380 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2381   print_on(st);
2382 
2383   // Print the per-region information.
2384   print_regions_on(st);
2385 }
2386 
2387 void G1CollectedHeap::print_on_error(outputStream* st) const {
2388   this->CollectedHeap::print_on_error(st);
2389 
2390   if (_cm != NULL) {
2391     st->cr();
2392     _cm->print_on_error(st);
2393   }
2394 }
2395 
2396 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2397   workers()->print_worker_threads_on(st);
2398   _cmThread->print_on(st);
2399   st->cr();
2400   _cm->print_worker_threads_on(st);
2401   _cr->print_threads_on(st);
2402   _young_gen_sampling_thread->print_on(st);
2403   if (G1StringDedup::is_enabled()) {
2404     G1StringDedup::print_worker_threads_on(st);
2405   }
2406 }
2407 
2408 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2409   workers()->threads_do(tc);
2410   tc->do_thread(_cmThread);
2411   _cm->threads_do(tc);
2412   _cr->threads_do(tc);
2413   tc->do_thread(_young_gen_sampling_thread);
2414   if (G1StringDedup::is_enabled()) {
2415     G1StringDedup::threads_do(tc);
2416   }
2417 }
2418 
2419 void G1CollectedHeap::print_tracing_info() const {
2420   g1_rem_set()->print_summary_info();
2421   concurrent_mark()->print_summary_info();
2422 }
2423 
2424 #ifndef PRODUCT
2425 // Helpful for debugging RSet issues.
2426 
2427 class PrintRSetsClosure : public HeapRegionClosure {
2428 private:
2429   const char* _msg;
2430   size_t _occupied_sum;
2431 
2432 public:
2433   bool do_heap_region(HeapRegion* r) {
2434     HeapRegionRemSet* hrrs = r->rem_set();
2435     size_t occupied = hrrs->occupied();
2436     _occupied_sum += occupied;
2437 
2438     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2439     if (occupied == 0) {
2440       tty->print_cr("  RSet is empty");
2441     } else {
2442       hrrs->print();
2443     }
2444     tty->print_cr("----------");
2445     return false;
2446   }
2447 
2448   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2449     tty->cr();
2450     tty->print_cr("========================================");
2451     tty->print_cr("%s", msg);
2452     tty->cr();
2453   }
2454 
2455   ~PrintRSetsClosure() {
2456     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2457     tty->print_cr("========================================");
2458     tty->cr();
2459   }
2460 };
2461 
2462 void G1CollectedHeap::print_cset_rsets() {
2463   PrintRSetsClosure cl("Printing CSet RSets");
2464   collection_set_iterate(&cl);
2465 }
2466 
2467 void G1CollectedHeap::print_all_rsets() {
2468   PrintRSetsClosure cl("Printing All RSets");;
2469   heap_region_iterate(&cl);
2470 }
2471 #endif // PRODUCT
2472 
2473 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2474 
2475   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2476   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2477   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2478 
2479   size_t eden_capacity_bytes =
2480     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2481 
2482   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2483   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2484                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2485 }
2486 
2487 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2488   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2489                        stats->unused(), stats->used(), stats->region_end_waste(),
2490                        stats->regions_filled(), stats->direct_allocated(),
2491                        stats->failure_used(), stats->failure_waste());
2492 }
2493 
2494 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2495   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2496   gc_tracer->report_gc_heap_summary(when, heap_summary);
2497 
2498   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2499   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2500 }
2501 
2502 G1CollectedHeap* G1CollectedHeap::heap() {
2503   CollectedHeap* heap = Universe::heap();
2504   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2505   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2506   return (G1CollectedHeap*)heap;
2507 }
2508 
2509 void G1CollectedHeap::gc_prologue(bool full) {
2510   // always_do_update_barrier = false;
2511   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2512 
2513   // This summary needs to be printed before incrementing total collections.
2514   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2515 
2516   // Update common counters.
2517   increment_total_collections(full /* full gc */);
2518   if (full) {
2519     increment_old_marking_cycles_started();
2520     reset_gc_time_stamp();
2521   } else {
2522     increment_gc_time_stamp();
2523   }
2524 
2525   // Fill TLAB's and such
2526   double start = os::elapsedTime();
2527   accumulate_statistics_all_tlabs();
2528   ensure_parsability(true);
2529   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2530 }
2531 
2532 void G1CollectedHeap::gc_epilogue(bool full) {
2533   // Update common counters.
2534   if (full) {
2535     // Update the number of full collections that have been completed.
2536     increment_old_marking_cycles_completed(false /* concurrent */);
2537   }
2538 
2539   // We are at the end of the GC. Total collections has already been increased.
2540   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2541 
2542   // FIXME: what is this about?
2543   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2544   // is set.
2545 #if COMPILER2_OR_JVMCI
2546   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2547 #endif
2548   // always_do_update_barrier = true;
2549 
2550   double start = os::elapsedTime();
2551   resize_all_tlabs();
2552   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2553 
2554   MemoryService::track_memory_usage();
2555   // We have just completed a GC. Update the soft reference
2556   // policy with the new heap occupancy
2557   Universe::update_heap_info_at_gc();
2558 }
2559 
2560 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2561                                                uint gc_count_before,
2562                                                bool* succeeded,
2563                                                GCCause::Cause gc_cause) {
2564   assert_heap_not_locked_and_not_at_safepoint();
2565   VM_G1CollectForAllocation op(word_size,
2566                                gc_count_before,
2567                                gc_cause,
2568                                false, /* should_initiate_conc_mark */
2569                                g1_policy()->max_pause_time_ms(),
2570                                AllocationContext::current());
2571   VMThread::execute(&op);
2572 
2573   HeapWord* result = op.result();
2574   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2575   assert(result == NULL || ret_succeeded,
2576          "the result should be NULL if the VM did not succeed");
2577   *succeeded = ret_succeeded;
2578 
2579   assert_heap_not_locked();
2580   return result;
2581 }
2582 
2583 void
2584 G1CollectedHeap::doConcurrentMark() {
2585   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2586   if (!_cmThread->in_progress()) {
2587     _cmThread->set_started();
2588     CGC_lock->notify();
2589   }
2590 }
2591 
2592 size_t G1CollectedHeap::pending_card_num() {
2593   size_t extra_cards = 0;
2594   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2595     DirtyCardQueue& dcq = curr->dirty_card_queue();
2596     extra_cards += dcq.size();
2597   }
2598   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2599   size_t buffer_size = dcqs.buffer_size();
2600   size_t buffer_num = dcqs.completed_buffers_num();
2601 
2602   return buffer_size * buffer_num + extra_cards;
2603 }
2604 
2605 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2606  private:
2607   size_t _total_humongous;
2608   size_t _candidate_humongous;
2609 
2610   DirtyCardQueue _dcq;
2611 
2612   // We don't nominate objects with many remembered set entries, on
2613   // the assumption that such objects are likely still live.
2614   bool is_remset_small(HeapRegion* region) const {
2615     HeapRegionRemSet* const rset = region->rem_set();
2616     return G1EagerReclaimHumongousObjectsWithStaleRefs
2617       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2618       : rset->is_empty();
2619   }
2620 
2621   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2622     assert(region->is_starts_humongous(), "Must start a humongous object");
2623 
2624     oop obj = oop(region->bottom());
2625 
2626     // Dead objects cannot be eager reclaim candidates. Due to class
2627     // unloading it is unsafe to query their classes so we return early.
2628     if (heap->is_obj_dead(obj, region)) {
2629       return false;
2630     }
2631 
2632     // Candidate selection must satisfy the following constraints
2633     // while concurrent marking is in progress:
2634     //
2635     // * In order to maintain SATB invariants, an object must not be
2636     // reclaimed if it was allocated before the start of marking and
2637     // has not had its references scanned.  Such an object must have
2638     // its references (including type metadata) scanned to ensure no
2639     // live objects are missed by the marking process.  Objects
2640     // allocated after the start of concurrent marking don't need to
2641     // be scanned.
2642     //
2643     // * An object must not be reclaimed if it is on the concurrent
2644     // mark stack.  Objects allocated after the start of concurrent
2645     // marking are never pushed on the mark stack.
2646     //
2647     // Nominating only objects allocated after the start of concurrent
2648     // marking is sufficient to meet both constraints.  This may miss
2649     // some objects that satisfy the constraints, but the marking data
2650     // structures don't support efficiently performing the needed
2651     // additional tests or scrubbing of the mark stack.
2652     //
2653     // However, we presently only nominate is_typeArray() objects.
2654     // A humongous object containing references induces remembered
2655     // set entries on other regions.  In order to reclaim such an
2656     // object, those remembered sets would need to be cleaned up.
2657     //
2658     // We also treat is_typeArray() objects specially, allowing them
2659     // to be reclaimed even if allocated before the start of
2660     // concurrent mark.  For this we rely on mark stack insertion to
2661     // exclude is_typeArray() objects, preventing reclaiming an object
2662     // that is in the mark stack.  We also rely on the metadata for
2663     // such objects to be built-in and so ensured to be kept live.
2664     // Frequent allocation and drop of large binary blobs is an
2665     // important use case for eager reclaim, and this special handling
2666     // may reduce needed headroom.
2667 
2668     return obj->is_typeArray() && is_remset_small(region);
2669   }
2670 
2671  public:
2672   RegisterHumongousWithInCSetFastTestClosure()
2673   : _total_humongous(0),
2674     _candidate_humongous(0),
2675     _dcq(&JavaThread::dirty_card_queue_set()) {
2676   }
2677 
2678   virtual bool do_heap_region(HeapRegion* r) {
2679     if (!r->is_starts_humongous()) {
2680       return false;
2681     }
2682     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2683 
2684     bool is_candidate = humongous_region_is_candidate(g1h, r);
2685     uint rindex = r->hrm_index();
2686     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2687     if (is_candidate) {
2688       _candidate_humongous++;
2689       g1h->register_humongous_region_with_cset(rindex);
2690       // Is_candidate already filters out humongous object with large remembered sets.
2691       // If we have a humongous object with a few remembered sets, we simply flush these
2692       // remembered set entries into the DCQS. That will result in automatic
2693       // re-evaluation of their remembered set entries during the following evacuation
2694       // phase.
2695       if (!r->rem_set()->is_empty()) {
2696         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2697                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2698         G1CardTable* ct = g1h->card_table();
2699         HeapRegionRemSetIterator hrrs(r->rem_set());
2700         size_t card_index;
2701         while (hrrs.has_next(card_index)) {
2702           jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2703           // The remembered set might contain references to already freed
2704           // regions. Filter out such entries to avoid failing card table
2705           // verification.
2706           if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2707             if (*card_ptr != G1CardTable::dirty_card_val()) {
2708               *card_ptr = G1CardTable::dirty_card_val();
2709               _dcq.enqueue(card_ptr);
2710             }
2711           }
2712         }
2713         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2714                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2715                hrrs.n_yielded(), r->rem_set()->occupied());
2716         r->rem_set()->clear_locked();
2717       }
2718       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2719     }
2720     _total_humongous++;
2721 
2722     return false;
2723   }
2724 
2725   size_t total_humongous() const { return _total_humongous; }
2726   size_t candidate_humongous() const { return _candidate_humongous; }
2727 
2728   void flush_rem_set_entries() { _dcq.flush(); }
2729 };
2730 
2731 void G1CollectedHeap::register_humongous_regions_with_cset() {
2732   if (!G1EagerReclaimHumongousObjects) {
2733     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2734     return;
2735   }
2736   double time = os::elapsed_counter();
2737 
2738   // Collect reclaim candidate information and register candidates with cset.
2739   RegisterHumongousWithInCSetFastTestClosure cl;
2740   heap_region_iterate(&cl);
2741 
2742   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2743   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2744                                                                   cl.total_humongous(),
2745                                                                   cl.candidate_humongous());
2746   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2747 
2748   // Finally flush all remembered set entries to re-check into the global DCQS.
2749   cl.flush_rem_set_entries();
2750 }
2751 
2752 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2753   public:
2754     bool do_heap_region(HeapRegion* hr) {
2755       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2756         hr->verify_rem_set();
2757       }
2758       return false;
2759     }
2760 };
2761 
2762 uint G1CollectedHeap::num_task_queues() const {
2763   return _task_queues->size();
2764 }
2765 
2766 #if TASKQUEUE_STATS
2767 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2768   st->print_raw_cr("GC Task Stats");
2769   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2770   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2771 }
2772 
2773 void G1CollectedHeap::print_taskqueue_stats() const {
2774   if (!log_is_enabled(Trace, gc, task, stats)) {
2775     return;
2776   }
2777   Log(gc, task, stats) log;
2778   ResourceMark rm;
2779   LogStream ls(log.trace());
2780   outputStream* st = &ls;
2781 
2782   print_taskqueue_stats_hdr(st);
2783 
2784   TaskQueueStats totals;
2785   const uint n = num_task_queues();
2786   for (uint i = 0; i < n; ++i) {
2787     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2788     totals += task_queue(i)->stats;
2789   }
2790   st->print_raw("tot "); totals.print(st); st->cr();
2791 
2792   DEBUG_ONLY(totals.verify());
2793 }
2794 
2795 void G1CollectedHeap::reset_taskqueue_stats() {
2796   const uint n = num_task_queues();
2797   for (uint i = 0; i < n; ++i) {
2798     task_queue(i)->stats.reset();
2799   }
2800 }
2801 #endif // TASKQUEUE_STATS
2802 
2803 void G1CollectedHeap::wait_for_root_region_scanning() {
2804   double scan_wait_start = os::elapsedTime();
2805   // We have to wait until the CM threads finish scanning the
2806   // root regions as it's the only way to ensure that all the
2807   // objects on them have been correctly scanned before we start
2808   // moving them during the GC.
2809   bool waited = _cm->root_regions()->wait_until_scan_finished();
2810   double wait_time_ms = 0.0;
2811   if (waited) {
2812     double scan_wait_end = os::elapsedTime();
2813     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2814   }
2815   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2816 }
2817 
2818 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2819 private:
2820   G1HRPrinter* _hr_printer;
2821 public:
2822   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2823 
2824   virtual bool do_heap_region(HeapRegion* r) {
2825     _hr_printer->cset(r);
2826     return false;
2827   }
2828 };
2829 
2830 void G1CollectedHeap::start_new_collection_set() {
2831   collection_set()->start_incremental_building();
2832 
2833   clear_cset_fast_test();
2834 
2835   guarantee(_eden.length() == 0, "eden should have been cleared");
2836   g1_policy()->transfer_survivors_to_cset(survivor());
2837 }
2838 
2839 bool
2840 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2841   assert_at_safepoint(true /* should_be_vm_thread */);
2842   guarantee(!is_gc_active(), "collection is not reentrant");
2843 
2844   if (GCLocker::check_active_before_gc()) {
2845     return false;
2846   }
2847 
2848   _gc_timer_stw->register_gc_start();
2849 
2850   GCIdMark gc_id_mark;
2851   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2852 
2853   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2854   ResourceMark rm;
2855 
2856   g1_policy()->note_gc_start();
2857 
2858   wait_for_root_region_scanning();
2859 
2860   print_heap_before_gc();
2861   print_heap_regions();
2862   trace_heap_before_gc(_gc_tracer_stw);
2863 
2864   _verifier->verify_region_sets_optional();
2865   _verifier->verify_dirty_young_regions();
2866 
2867   // We should not be doing initial mark unless the conc mark thread is running
2868   if (!_cmThread->should_terminate()) {
2869     // This call will decide whether this pause is an initial-mark
2870     // pause. If it is, during_initial_mark_pause() will return true
2871     // for the duration of this pause.
2872     g1_policy()->decide_on_conc_mark_initiation();
2873   }
2874 
2875   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2876   assert(!collector_state()->during_initial_mark_pause() ||
2877           collector_state()->gcs_are_young(), "sanity");
2878 
2879   // We also do not allow mixed GCs during marking.
2880   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2881 
2882   // Record whether this pause is an initial mark. When the current
2883   // thread has completed its logging output and it's safe to signal
2884   // the CM thread, the flag's value in the policy has been reset.
2885   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2886 
2887   // Inner scope for scope based logging, timers, and stats collection
2888   {
2889     EvacuationInfo evacuation_info;
2890 
2891     if (collector_state()->during_initial_mark_pause()) {
2892       // We are about to start a marking cycle, so we increment the
2893       // full collection counter.
2894       increment_old_marking_cycles_started();
2895       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2896     }
2897 
2898     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2899 
2900     GCTraceCPUTime tcpu;
2901 
2902     G1HeapVerifier::G1VerifyType verify_type;
2903     FormatBuffer<> gc_string("Pause ");
2904     if (collector_state()->during_initial_mark_pause()) {
2905       gc_string.append("Initial Mark");
2906       verify_type = G1HeapVerifier::G1VerifyInitialMark;
2907     } else if (collector_state()->gcs_are_young()) {
2908       gc_string.append("Young");
2909       verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2910     } else {
2911       gc_string.append("Mixed");
2912       verify_type = G1HeapVerifier::G1VerifyMixed;
2913     }
2914     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2915 
2916     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2917                                                                   workers()->active_workers(),
2918                                                                   Threads::number_of_non_daemon_threads());
2919     workers()->update_active_workers(active_workers);
2920     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2921 
2922     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2923     TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2924 
2925     // If the secondary_free_list is not empty, append it to the
2926     // free_list. No need to wait for the cleanup operation to finish;
2927     // the region allocation code will check the secondary_free_list
2928     // and wait if necessary. If the G1StressConcRegionFreeing flag is
2929     // set, skip this step so that the region allocation code has to
2930     // get entries from the secondary_free_list.
2931     if (!G1StressConcRegionFreeing) {
2932       append_secondary_free_list_if_not_empty_with_lock();
2933     }
2934 
2935     G1HeapTransition heap_transition(this);
2936     size_t heap_used_bytes_before_gc = used();
2937 
2938     // Don't dynamically change the number of GC threads this early.  A value of
2939     // 0 is used to indicate serial work.  When parallel work is done,
2940     // it will be set.
2941 
2942     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2943       IsGCActiveMark x;
2944 
2945       gc_prologue(false);
2946 
2947       if (VerifyRememberedSets) {
2948         log_info(gc, verify)("[Verifying RemSets before GC]");
2949         VerifyRegionRemSetClosure v_cl;
2950         heap_region_iterate(&v_cl);
2951       }
2952 
2953       _verifier->verify_before_gc(verify_type);
2954 
2955       _verifier->check_bitmaps("GC Start");
2956 
2957 #if COMPILER2_OR_JVMCI
2958       DerivedPointerTable::clear();
2959 #endif
2960 
2961       // Please see comment in g1CollectedHeap.hpp and
2962       // G1CollectedHeap::ref_processing_init() to see how
2963       // reference processing currently works in G1.
2964 
2965       // Enable discovery in the STW reference processor
2966       if (g1_policy()->should_process_references()) {
2967         ref_processor_stw()->enable_discovery();
2968       } else {
2969         ref_processor_stw()->disable_discovery();
2970       }
2971 
2972       {
2973         // We want to temporarily turn off discovery by the
2974         // CM ref processor, if necessary, and turn it back on
2975         // on again later if we do. Using a scoped
2976         // NoRefDiscovery object will do this.
2977         NoRefDiscovery no_cm_discovery(ref_processor_cm());
2978 
2979         // Forget the current alloc region (we might even choose it to be part
2980         // of the collection set!).
2981         _allocator->release_mutator_alloc_region();
2982 
2983         // This timing is only used by the ergonomics to handle our pause target.
2984         // It is unclear why this should not include the full pause. We will
2985         // investigate this in CR 7178365.
2986         //
2987         // Preserving the old comment here if that helps the investigation:
2988         //
2989         // The elapsed time induced by the start time below deliberately elides
2990         // the possible verification above.
2991         double sample_start_time_sec = os::elapsedTime();
2992 
2993         g1_policy()->record_collection_pause_start(sample_start_time_sec);
2994 
2995         if (collector_state()->during_initial_mark_pause()) {
2996           concurrent_mark()->checkpoint_roots_initial_pre();
2997         }
2998 
2999         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3000 
3001         evacuation_info.set_collectionset_regions(collection_set()->region_length());
3002 
3003         // Make sure the remembered sets are up to date. This needs to be
3004         // done before register_humongous_regions_with_cset(), because the
3005         // remembered sets are used there to choose eager reclaim candidates.
3006         // If the remembered sets are not up to date we might miss some
3007         // entries that need to be handled.
3008         g1_rem_set()->cleanupHRRS();
3009 
3010         register_humongous_regions_with_cset();
3011 
3012         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3013 
3014         // We call this after finalize_cset() to
3015         // ensure that the CSet has been finalized.
3016         _cm->verify_no_cset_oops();
3017 
3018         if (_hr_printer.is_active()) {
3019           G1PrintCollectionSetClosure cl(&_hr_printer);
3020           _collection_set.iterate(&cl);
3021         }
3022 
3023         // Initialize the GC alloc regions.
3024         _allocator->init_gc_alloc_regions(evacuation_info);
3025 
3026         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3027         pre_evacuate_collection_set();
3028 
3029         // Actually do the work...
3030         evacuate_collection_set(evacuation_info, &per_thread_states);
3031 
3032         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3033 
3034         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3035         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3036 
3037         eagerly_reclaim_humongous_regions();
3038 
3039         record_obj_copy_mem_stats();
3040         _survivor_evac_stats.adjust_desired_plab_sz();
3041         _old_evac_stats.adjust_desired_plab_sz();
3042 
3043         double start = os::elapsedTime();
3044         start_new_collection_set();
3045         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3046 
3047         if (evacuation_failed()) {
3048           set_used(recalculate_used());
3049           if (_archive_allocator != NULL) {
3050             _archive_allocator->clear_used();
3051           }
3052           for (uint i = 0; i < ParallelGCThreads; i++) {
3053             if (_evacuation_failed_info_array[i].has_failed()) {
3054               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3055             }
3056           }
3057         } else {
3058           // The "used" of the the collection set have already been subtracted
3059           // when they were freed.  Add in the bytes evacuated.
3060           increase_used(g1_policy()->bytes_copied_during_gc());
3061         }
3062 
3063         if (collector_state()->during_initial_mark_pause()) {
3064           // We have to do this before we notify the CM threads that
3065           // they can start working to make sure that all the
3066           // appropriate initialization is done on the CM object.
3067           concurrent_mark()->checkpoint_roots_initial_post();
3068           collector_state()->set_mark_in_progress(true);
3069           // Note that we don't actually trigger the CM thread at
3070           // this point. We do that later when we're sure that
3071           // the current thread has completed its logging output.
3072         }
3073 
3074         allocate_dummy_regions();
3075 
3076         _allocator->init_mutator_alloc_region();
3077 
3078         {
3079           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3080           if (expand_bytes > 0) {
3081             size_t bytes_before = capacity();
3082             // No need for an ergo logging here,
3083             // expansion_amount() does this when it returns a value > 0.
3084             double expand_ms;
3085             if (!expand(expand_bytes, _workers, &expand_ms)) {
3086               // We failed to expand the heap. Cannot do anything about it.
3087             }
3088             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3089           }
3090         }
3091 
3092         // We redo the verification but now wrt to the new CSet which
3093         // has just got initialized after the previous CSet was freed.
3094         _cm->verify_no_cset_oops();
3095 
3096         // This timing is only used by the ergonomics to handle our pause target.
3097         // It is unclear why this should not include the full pause. We will
3098         // investigate this in CR 7178365.
3099         double sample_end_time_sec = os::elapsedTime();
3100         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3101         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3102         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3103 
3104         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3105         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3106 
3107         if (VerifyRememberedSets) {
3108           log_info(gc, verify)("[Verifying RemSets after GC]");
3109           VerifyRegionRemSetClosure v_cl;
3110           heap_region_iterate(&v_cl);
3111         }
3112 
3113         _verifier->verify_after_gc(verify_type);
3114         _verifier->check_bitmaps("GC End");
3115 
3116         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3117         ref_processor_stw()->verify_no_references_recorded();
3118 
3119         // CM reference discovery will be re-enabled if necessary.
3120       }
3121 
3122 #ifdef TRACESPINNING
3123       ParallelTaskTerminator::print_termination_counts();
3124 #endif
3125 
3126       gc_epilogue(false);
3127     }
3128 
3129     // Print the remainder of the GC log output.
3130     if (evacuation_failed()) {
3131       log_info(gc)("To-space exhausted");
3132     }
3133 
3134     g1_policy()->print_phases();
3135     heap_transition.print();
3136 
3137     // It is not yet to safe to tell the concurrent mark to
3138     // start as we have some optional output below. We don't want the
3139     // output from the concurrent mark thread interfering with this
3140     // logging output either.
3141 
3142     _hrm.verify_optional();
3143     _verifier->verify_region_sets_optional();
3144 
3145     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3146     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3147 
3148     print_heap_after_gc();
3149     print_heap_regions();
3150     trace_heap_after_gc(_gc_tracer_stw);
3151 
3152     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3153     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3154     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3155     // before any GC notifications are raised.
3156     g1mm()->update_sizes();
3157 
3158     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3159     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3160     _gc_timer_stw->register_gc_end();
3161     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3162   }
3163   // It should now be safe to tell the concurrent mark thread to start
3164   // without its logging output interfering with the logging output
3165   // that came from the pause.
3166 
3167   if (should_start_conc_mark) {
3168     // CAUTION: after the doConcurrentMark() call below,
3169     // the concurrent marking thread(s) could be running
3170     // concurrently with us. Make sure that anything after
3171     // this point does not assume that we are the only GC thread
3172     // running. Note: of course, the actual marking work will
3173     // not start until the safepoint itself is released in
3174     // SuspendibleThreadSet::desynchronize().
3175     doConcurrentMark();
3176   }
3177 
3178   return true;
3179 }
3180 
3181 void G1CollectedHeap::remove_self_forwarding_pointers() {
3182   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3183   workers()->run_task(&rsfp_task);
3184 }
3185 
3186 void G1CollectedHeap::restore_after_evac_failure() {
3187   double remove_self_forwards_start = os::elapsedTime();
3188 
3189   remove_self_forwarding_pointers();
3190   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3191   _preserved_marks_set.restore(&task_executor);
3192 
3193   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3194 }
3195 
3196 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3197   if (!_evacuation_failed) {
3198     _evacuation_failed = true;
3199   }
3200 
3201   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3202   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3203 }
3204 
3205 bool G1ParEvacuateFollowersClosure::offer_termination() {
3206   G1ParScanThreadState* const pss = par_scan_state();
3207   start_term_time();
3208   const bool res = terminator()->offer_termination();
3209   end_term_time();
3210   return res;
3211 }
3212 
3213 void G1ParEvacuateFollowersClosure::do_void() {
3214   G1ParScanThreadState* const pss = par_scan_state();
3215   pss->trim_queue();
3216   do {
3217     pss->steal_and_trim_queue(queues());
3218   } while (!offer_termination());
3219 }
3220 
3221 class G1ParTask : public AbstractGangTask {
3222 protected:
3223   G1CollectedHeap*         _g1h;
3224   G1ParScanThreadStateSet* _pss;
3225   RefToScanQueueSet*       _queues;
3226   G1RootProcessor*         _root_processor;
3227   ParallelTaskTerminator   _terminator;
3228   uint                     _n_workers;
3229 
3230 public:
3231   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3232     : AbstractGangTask("G1 collection"),
3233       _g1h(g1h),
3234       _pss(per_thread_states),
3235       _queues(task_queues),
3236       _root_processor(root_processor),
3237       _terminator(n_workers, _queues),
3238       _n_workers(n_workers)
3239   {}
3240 
3241   void work(uint worker_id) {
3242     if (worker_id >= _n_workers) return;  // no work needed this round
3243 
3244     double start_sec = os::elapsedTime();
3245     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3246 
3247     {
3248       ResourceMark rm;
3249       HandleMark   hm;
3250 
3251       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3252 
3253       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3254       pss->set_ref_processor(rp);
3255 
3256       double start_strong_roots_sec = os::elapsedTime();
3257 
3258       _root_processor->evacuate_roots(pss->closures(), worker_id);
3259 
3260       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3261       // treating the nmethods visited to act as roots for concurrent marking.
3262       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3263       // objects copied by the current evacuation.
3264       _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3265                                                       pss->closures()->weak_codeblobs(),
3266                                                       worker_id);
3267 
3268       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3269 
3270       double term_sec = 0.0;
3271       size_t evac_term_attempts = 0;
3272       {
3273         double start = os::elapsedTime();
3274         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3275         evac.do_void();
3276 
3277         evac_term_attempts = evac.term_attempts();
3278         term_sec = evac.term_time();
3279         double elapsed_sec = os::elapsedTime() - start;
3280         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3281         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3282         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3283       }
3284 
3285       assert(pss->queue_is_empty(), "should be empty");
3286 
3287       if (log_is_enabled(Debug, gc, task, stats)) {
3288         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3289         size_t lab_waste;
3290         size_t lab_undo_waste;
3291         pss->waste(lab_waste, lab_undo_waste);
3292         _g1h->print_termination_stats(worker_id,
3293                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3294                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3295                                       term_sec * 1000.0,                          /* evac term time */
3296                                       evac_term_attempts,                         /* evac term attempts */
3297                                       lab_waste,                                  /* alloc buffer waste */
3298                                       lab_undo_waste                              /* undo waste */
3299                                       );
3300       }
3301 
3302       // Close the inner scope so that the ResourceMark and HandleMark
3303       // destructors are executed here and are included as part of the
3304       // "GC Worker Time".
3305     }
3306     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3307   }
3308 };
3309 
3310 void G1CollectedHeap::print_termination_stats_hdr() {
3311   log_debug(gc, task, stats)("GC Termination Stats");
3312   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3313   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3314   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3315 }
3316 
3317 void G1CollectedHeap::print_termination_stats(uint worker_id,
3318                                               double elapsed_ms,
3319                                               double strong_roots_ms,
3320                                               double term_ms,
3321                                               size_t term_attempts,
3322                                               size_t alloc_buffer_waste,
3323                                               size_t undo_waste) const {
3324   log_debug(gc, task, stats)
3325               ("%3d %9.2f %9.2f %6.2f "
3326                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3327                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3328                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3329                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3330                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3331                alloc_buffer_waste * HeapWordSize / K,
3332                undo_waste * HeapWordSize / K);
3333 }
3334 
3335 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3336 private:
3337   BoolObjectClosure* _is_alive;
3338   G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3339 
3340   int _initial_string_table_size;
3341   int _initial_symbol_table_size;
3342 
3343   bool  _process_strings;
3344   int _strings_processed;
3345   int _strings_removed;
3346 
3347   bool  _process_symbols;
3348   int _symbols_processed;
3349   int _symbols_removed;
3350 
3351   bool _process_string_dedup;
3352 
3353 public:
3354   G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3355     AbstractGangTask("String/Symbol Unlinking"),
3356     _is_alive(is_alive),
3357     _dedup_closure(is_alive, NULL, false),
3358     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3359     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3360     _process_string_dedup(process_string_dedup) {
3361 
3362     _initial_string_table_size = StringTable::the_table()->table_size();
3363     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3364     if (process_strings) {
3365       StringTable::clear_parallel_claimed_index();
3366     }
3367     if (process_symbols) {
3368       SymbolTable::clear_parallel_claimed_index();
3369     }
3370   }
3371 
3372   ~G1StringAndSymbolCleaningTask() {
3373     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3374               "claim value %d after unlink less than initial string table size %d",
3375               StringTable::parallel_claimed_index(), _initial_string_table_size);
3376     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3377               "claim value %d after unlink less than initial symbol table size %d",
3378               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3379 
3380     log_info(gc, stringtable)(
3381         "Cleaned string and symbol table, "
3382         "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3383         "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3384         strings_processed(), strings_removed(),
3385         symbols_processed(), symbols_removed());
3386   }
3387 
3388   void work(uint worker_id) {
3389     int strings_processed = 0;
3390     int strings_removed = 0;
3391     int symbols_processed = 0;
3392     int symbols_removed = 0;
3393     if (_process_strings) {
3394       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3395       Atomic::add(strings_processed, &_strings_processed);
3396       Atomic::add(strings_removed, &_strings_removed);
3397     }
3398     if (_process_symbols) {
3399       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3400       Atomic::add(symbols_processed, &_symbols_processed);
3401       Atomic::add(symbols_removed, &_symbols_removed);
3402     }
3403     if (_process_string_dedup) {
3404       G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3405     }
3406   }
3407 
3408   size_t strings_processed() const { return (size_t)_strings_processed; }
3409   size_t strings_removed()   const { return (size_t)_strings_removed; }
3410 
3411   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3412   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3413 };
3414 
3415 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3416 private:
3417   static Monitor* _lock;
3418 
3419   BoolObjectClosure* const _is_alive;
3420   const bool               _unloading_occurred;
3421   const uint               _num_workers;
3422 
3423   // Variables used to claim nmethods.
3424   CompiledMethod* _first_nmethod;
3425   CompiledMethod* volatile _claimed_nmethod;
3426 
3427   // The list of nmethods that need to be processed by the second pass.
3428   CompiledMethod* volatile _postponed_list;
3429   volatile uint            _num_entered_barrier;
3430 
3431  public:
3432   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3433       _is_alive(is_alive),
3434       _unloading_occurred(unloading_occurred),
3435       _num_workers(num_workers),
3436       _first_nmethod(NULL),
3437       _claimed_nmethod(NULL),
3438       _postponed_list(NULL),
3439       _num_entered_barrier(0)
3440   {
3441     CompiledMethod::increase_unloading_clock();
3442     // Get first alive nmethod
3443     CompiledMethodIterator iter = CompiledMethodIterator();
3444     if(iter.next_alive()) {
3445       _first_nmethod = iter.method();
3446     }
3447     _claimed_nmethod = _first_nmethod;
3448   }
3449 
3450   ~G1CodeCacheUnloadingTask() {
3451     CodeCache::verify_clean_inline_caches();
3452 
3453     CodeCache::set_needs_cache_clean(false);
3454     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3455 
3456     CodeCache::verify_icholder_relocations();
3457   }
3458 
3459  private:
3460   void add_to_postponed_list(CompiledMethod* nm) {
3461       CompiledMethod* old;
3462       do {
3463         old = _postponed_list;
3464         nm->set_unloading_next(old);
3465       } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3466   }
3467 
3468   void clean_nmethod(CompiledMethod* nm) {
3469     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3470 
3471     if (postponed) {
3472       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3473       add_to_postponed_list(nm);
3474     }
3475 
3476     // Mark that this thread has been cleaned/unloaded.
3477     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3478     nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3479   }
3480 
3481   void clean_nmethod_postponed(CompiledMethod* nm) {
3482     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3483   }
3484 
3485   static const int MaxClaimNmethods = 16;
3486 
3487   void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3488     CompiledMethod* first;
3489     CompiledMethodIterator last;
3490 
3491     do {
3492       *num_claimed_nmethods = 0;
3493 
3494       first = _claimed_nmethod;
3495       last = CompiledMethodIterator(first);
3496 
3497       if (first != NULL) {
3498 
3499         for (int i = 0; i < MaxClaimNmethods; i++) {
3500           if (!last.next_alive()) {
3501             break;
3502           }
3503           claimed_nmethods[i] = last.method();
3504           (*num_claimed_nmethods)++;
3505         }
3506       }
3507 
3508     } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3509   }
3510 
3511   CompiledMethod* claim_postponed_nmethod() {
3512     CompiledMethod* claim;
3513     CompiledMethod* next;
3514 
3515     do {
3516       claim = _postponed_list;
3517       if (claim == NULL) {
3518         return NULL;
3519       }
3520 
3521       next = claim->unloading_next();
3522 
3523     } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3524 
3525     return claim;
3526   }
3527 
3528  public:
3529   // Mark that we're done with the first pass of nmethod cleaning.
3530   void barrier_mark(uint worker_id) {
3531     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3532     _num_entered_barrier++;
3533     if (_num_entered_barrier == _num_workers) {
3534       ml.notify_all();
3535     }
3536   }
3537 
3538   // See if we have to wait for the other workers to
3539   // finish their first-pass nmethod cleaning work.
3540   void barrier_wait(uint worker_id) {
3541     if (_num_entered_barrier < _num_workers) {
3542       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3543       while (_num_entered_barrier < _num_workers) {
3544           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3545       }
3546     }
3547   }
3548 
3549   // Cleaning and unloading of nmethods. Some work has to be postponed
3550   // to the second pass, when we know which nmethods survive.
3551   void work_first_pass(uint worker_id) {
3552     // The first nmethods is claimed by the first worker.
3553     if (worker_id == 0 && _first_nmethod != NULL) {
3554       clean_nmethod(_first_nmethod);
3555       _first_nmethod = NULL;
3556     }
3557 
3558     int num_claimed_nmethods;
3559     CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3560 
3561     while (true) {
3562       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3563 
3564       if (num_claimed_nmethods == 0) {
3565         break;
3566       }
3567 
3568       for (int i = 0; i < num_claimed_nmethods; i++) {
3569         clean_nmethod(claimed_nmethods[i]);
3570       }
3571     }
3572   }
3573 
3574   void work_second_pass(uint worker_id) {
3575     CompiledMethod* nm;
3576     // Take care of postponed nmethods.
3577     while ((nm = claim_postponed_nmethod()) != NULL) {
3578       clean_nmethod_postponed(nm);
3579     }
3580   }
3581 };
3582 
3583 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3584 
3585 class G1KlassCleaningTask : public StackObj {
3586   BoolObjectClosure*                      _is_alive;
3587   volatile int                            _clean_klass_tree_claimed;
3588   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3589 
3590  public:
3591   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3592       _is_alive(is_alive),
3593       _clean_klass_tree_claimed(0),
3594       _klass_iterator() {
3595   }
3596 
3597  private:
3598   bool claim_clean_klass_tree_task() {
3599     if (_clean_klass_tree_claimed) {
3600       return false;
3601     }
3602 
3603     return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3604   }
3605 
3606   InstanceKlass* claim_next_klass() {
3607     Klass* klass;
3608     do {
3609       klass =_klass_iterator.next_klass();
3610     } while (klass != NULL && !klass->is_instance_klass());
3611 
3612     // this can be null so don't call InstanceKlass::cast
3613     return static_cast<InstanceKlass*>(klass);
3614   }
3615 
3616 public:
3617 
3618   void clean_klass(InstanceKlass* ik) {
3619     ik->clean_weak_instanceklass_links(_is_alive);
3620   }
3621 
3622   void work() {
3623     ResourceMark rm;
3624 
3625     // One worker will clean the subklass/sibling klass tree.
3626     if (claim_clean_klass_tree_task()) {
3627       Klass::clean_subklass_tree(_is_alive);
3628     }
3629 
3630     // All workers will help cleaning the classes,
3631     InstanceKlass* klass;
3632     while ((klass = claim_next_klass()) != NULL) {
3633       clean_klass(klass);
3634     }
3635   }
3636 };
3637 
3638 class G1ResolvedMethodCleaningTask : public StackObj {
3639   BoolObjectClosure* _is_alive;
3640   volatile int       _resolved_method_task_claimed;
3641 public:
3642   G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3643       _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3644 
3645   bool claim_resolved_method_task() {
3646     if (_resolved_method_task_claimed) {
3647       return false;
3648     }
3649     return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3650   }
3651 
3652   // These aren't big, one thread can do it all.
3653   void work() {
3654     if (claim_resolved_method_task()) {
3655       ResolvedMethodTable::unlink(_is_alive);
3656     }
3657   }
3658 };
3659 
3660 
3661 // To minimize the remark pause times, the tasks below are done in parallel.
3662 class G1ParallelCleaningTask : public AbstractGangTask {
3663 private:
3664   G1StringAndSymbolCleaningTask _string_symbol_task;
3665   G1CodeCacheUnloadingTask      _code_cache_task;
3666   G1KlassCleaningTask           _klass_cleaning_task;
3667   G1ResolvedMethodCleaningTask  _resolved_method_cleaning_task;
3668 
3669 public:
3670   // The constructor is run in the VMThread.
3671   G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3672       AbstractGangTask("Parallel Cleaning"),
3673       _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3674       _code_cache_task(num_workers, is_alive, unloading_occurred),
3675       _klass_cleaning_task(is_alive),
3676       _resolved_method_cleaning_task(is_alive) {
3677   }
3678 
3679   // The parallel work done by all worker threads.
3680   void work(uint worker_id) {
3681     // Do first pass of code cache cleaning.
3682     _code_cache_task.work_first_pass(worker_id);
3683 
3684     // Let the threads mark that the first pass is done.
3685     _code_cache_task.barrier_mark(worker_id);
3686 
3687     // Clean the Strings and Symbols.
3688     _string_symbol_task.work(worker_id);
3689 
3690     // Clean unreferenced things in the ResolvedMethodTable
3691     _resolved_method_cleaning_task.work();
3692 
3693     // Wait for all workers to finish the first code cache cleaning pass.
3694     _code_cache_task.barrier_wait(worker_id);
3695 
3696     // Do the second code cache cleaning work, which realize on
3697     // the liveness information gathered during the first pass.
3698     _code_cache_task.work_second_pass(worker_id);
3699 
3700     // Clean all klasses that were not unloaded.
3701     _klass_cleaning_task.work();
3702   }
3703 };
3704 
3705 
3706 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3707                                         bool class_unloading_occurred) {
3708   uint n_workers = workers()->active_workers();
3709 
3710   G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3711   workers()->run_task(&g1_unlink_task);
3712 }
3713 
3714 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3715                                        bool process_strings,
3716                                        bool process_symbols,
3717                                        bool process_string_dedup) {
3718   if (!process_strings && !process_symbols && !process_string_dedup) {
3719     // Nothing to clean.
3720     return;
3721   }
3722 
3723   G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3724   workers()->run_task(&g1_unlink_task);
3725 
3726 }
3727 
3728 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3729  private:
3730   DirtyCardQueueSet* _queue;
3731   G1CollectedHeap* _g1h;
3732  public:
3733   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3734     _queue(queue), _g1h(g1h) { }
3735 
3736   virtual void work(uint worker_id) {
3737     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3738     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3739 
3740     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3741     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3742 
3743     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3744   }
3745 };
3746 
3747 void G1CollectedHeap::redirty_logged_cards() {
3748   double redirty_logged_cards_start = os::elapsedTime();
3749 
3750   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3751   dirty_card_queue_set().reset_for_par_iteration();
3752   workers()->run_task(&redirty_task);
3753 
3754   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3755   dcq.merge_bufferlists(&dirty_card_queue_set());
3756   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3757 
3758   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3759 }
3760 
3761 // Weak Reference Processing support
3762 
3763 // An always "is_alive" closure that is used to preserve referents.
3764 // If the object is non-null then it's alive.  Used in the preservation
3765 // of referent objects that are pointed to by reference objects
3766 // discovered by the CM ref processor.
3767 class G1AlwaysAliveClosure: public BoolObjectClosure {
3768   G1CollectedHeap* _g1;
3769 public:
3770   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3771   bool do_object_b(oop p) {
3772     if (p != NULL) {
3773       return true;
3774     }
3775     return false;
3776   }
3777 };
3778 
3779 bool G1STWIsAliveClosure::do_object_b(oop p) {
3780   // An object is reachable if it is outside the collection set,
3781   // or is inside and copied.
3782   return !_g1->is_in_cset(p) || p->is_forwarded();
3783 }
3784 
3785 // Non Copying Keep Alive closure
3786 class G1KeepAliveClosure: public OopClosure {
3787   G1CollectedHeap* _g1;
3788 public:
3789   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3790   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3791   void do_oop(oop* p) {
3792     oop obj = *p;
3793     assert(obj != NULL, "the caller should have filtered out NULL values");
3794 
3795     const InCSetState cset_state = _g1->in_cset_state(obj);
3796     if (!cset_state.is_in_cset_or_humongous()) {
3797       return;
3798     }
3799     if (cset_state.is_in_cset()) {
3800       assert( obj->is_forwarded(), "invariant" );
3801       *p = obj->forwardee();
3802     } else {
3803       assert(!obj->is_forwarded(), "invariant" );
3804       assert(cset_state.is_humongous(),
3805              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3806       _g1->set_humongous_is_live(obj);
3807     }
3808   }
3809 };
3810 
3811 // Copying Keep Alive closure - can be called from both
3812 // serial and parallel code as long as different worker
3813 // threads utilize different G1ParScanThreadState instances
3814 // and different queues.
3815 
3816 class G1CopyingKeepAliveClosure: public OopClosure {
3817   G1CollectedHeap*         _g1h;
3818   OopClosure*              _copy_non_heap_obj_cl;
3819   G1ParScanThreadState*    _par_scan_state;
3820 
3821 public:
3822   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3823                             OopClosure* non_heap_obj_cl,
3824                             G1ParScanThreadState* pss):
3825     _g1h(g1h),
3826     _copy_non_heap_obj_cl(non_heap_obj_cl),
3827     _par_scan_state(pss)
3828   {}
3829 
3830   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3831   virtual void do_oop(      oop* p) { do_oop_work(p); }
3832 
3833   template <class T> void do_oop_work(T* p) {
3834     oop obj = oopDesc::load_decode_heap_oop(p);
3835 
3836     if (_g1h->is_in_cset_or_humongous(obj)) {
3837       // If the referent object has been forwarded (either copied
3838       // to a new location or to itself in the event of an
3839       // evacuation failure) then we need to update the reference
3840       // field and, if both reference and referent are in the G1
3841       // heap, update the RSet for the referent.
3842       //
3843       // If the referent has not been forwarded then we have to keep
3844       // it alive by policy. Therefore we have copy the referent.
3845       //
3846       // If the reference field is in the G1 heap then we can push
3847       // on the PSS queue. When the queue is drained (after each
3848       // phase of reference processing) the object and it's followers
3849       // will be copied, the reference field set to point to the
3850       // new location, and the RSet updated. Otherwise we need to
3851       // use the the non-heap or metadata closures directly to copy
3852       // the referent object and update the pointer, while avoiding
3853       // updating the RSet.
3854 
3855       if (_g1h->is_in_g1_reserved(p)) {
3856         _par_scan_state->push_on_queue(p);
3857       } else {
3858         assert(!Metaspace::contains((const void*)p),
3859                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3860         _copy_non_heap_obj_cl->do_oop(p);
3861       }
3862     }
3863   }
3864 };
3865 
3866 // Serial drain queue closure. Called as the 'complete_gc'
3867 // closure for each discovered list in some of the
3868 // reference processing phases.
3869 
3870 class G1STWDrainQueueClosure: public VoidClosure {
3871 protected:
3872   G1CollectedHeap* _g1h;
3873   G1ParScanThreadState* _par_scan_state;
3874 
3875   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3876 
3877 public:
3878   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3879     _g1h(g1h),
3880     _par_scan_state(pss)
3881   { }
3882 
3883   void do_void() {
3884     G1ParScanThreadState* const pss = par_scan_state();
3885     pss->trim_queue();
3886   }
3887 };
3888 
3889 // Parallel Reference Processing closures
3890 
3891 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3892 // processing during G1 evacuation pauses.
3893 
3894 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3895 private:
3896   G1CollectedHeap*          _g1h;
3897   G1ParScanThreadStateSet*  _pss;
3898   RefToScanQueueSet*        _queues;
3899   WorkGang*                 _workers;
3900   uint                      _active_workers;
3901 
3902 public:
3903   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3904                            G1ParScanThreadStateSet* per_thread_states,
3905                            WorkGang* workers,
3906                            RefToScanQueueSet *task_queues,
3907                            uint n_workers) :
3908     _g1h(g1h),
3909     _pss(per_thread_states),
3910     _queues(task_queues),
3911     _workers(workers),
3912     _active_workers(n_workers)
3913   {
3914     g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3915   }
3916 
3917   // Executes the given task using concurrent marking worker threads.
3918   virtual void execute(ProcessTask& task);
3919   virtual void execute(EnqueueTask& task);
3920 };
3921 
3922 // Gang task for possibly parallel reference processing
3923 
3924 class G1STWRefProcTaskProxy: public AbstractGangTask {
3925   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3926   ProcessTask&     _proc_task;
3927   G1CollectedHeap* _g1h;
3928   G1ParScanThreadStateSet* _pss;
3929   RefToScanQueueSet* _task_queues;
3930   ParallelTaskTerminator* _terminator;
3931 
3932 public:
3933   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3934                         G1CollectedHeap* g1h,
3935                         G1ParScanThreadStateSet* per_thread_states,
3936                         RefToScanQueueSet *task_queues,
3937                         ParallelTaskTerminator* terminator) :
3938     AbstractGangTask("Process reference objects in parallel"),
3939     _proc_task(proc_task),
3940     _g1h(g1h),
3941     _pss(per_thread_states),
3942     _task_queues(task_queues),
3943     _terminator(terminator)
3944   {}
3945 
3946   virtual void work(uint worker_id) {
3947     // The reference processing task executed by a single worker.
3948     ResourceMark rm;
3949     HandleMark   hm;
3950 
3951     G1STWIsAliveClosure is_alive(_g1h);
3952 
3953     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
3954     pss->set_ref_processor(NULL);
3955 
3956     // Keep alive closure.
3957     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3958 
3959     // Complete GC closure
3960     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3961 
3962     // Call the reference processing task's work routine.
3963     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3964 
3965     // Note we cannot assert that the refs array is empty here as not all
3966     // of the processing tasks (specifically phase2 - pp2_work) execute
3967     // the complete_gc closure (which ordinarily would drain the queue) so
3968     // the queue may not be empty.
3969   }
3970 };
3971 
3972 // Driver routine for parallel reference processing.
3973 // Creates an instance of the ref processing gang
3974 // task and has the worker threads execute it.
3975 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3976   assert(_workers != NULL, "Need parallel worker threads.");
3977 
3978   ParallelTaskTerminator terminator(_active_workers, _queues);
3979   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3980 
3981   _workers->run_task(&proc_task_proxy);
3982 }
3983 
3984 // Gang task for parallel reference enqueueing.
3985 
3986 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
3987   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
3988   EnqueueTask& _enq_task;
3989 
3990 public:
3991   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
3992     AbstractGangTask("Enqueue reference objects in parallel"),
3993     _enq_task(enq_task)
3994   { }
3995 
3996   virtual void work(uint worker_id) {
3997     _enq_task.work(worker_id);
3998   }
3999 };
4000 
4001 // Driver routine for parallel reference enqueueing.
4002 // Creates an instance of the ref enqueueing gang
4003 // task and has the worker threads execute it.
4004 
4005 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4006   assert(_workers != NULL, "Need parallel worker threads.");
4007 
4008   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4009 
4010   _workers->run_task(&enq_task_proxy);
4011 }
4012 
4013 // End of weak reference support closures
4014 
4015 // Abstract task used to preserve (i.e. copy) any referent objects
4016 // that are in the collection set and are pointed to by reference
4017 // objects discovered by the CM ref processor.
4018 
4019 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4020 protected:
4021   G1CollectedHeap*         _g1h;
4022   G1ParScanThreadStateSet* _pss;
4023   RefToScanQueueSet*       _queues;
4024   ParallelTaskTerminator   _terminator;
4025   uint                     _n_workers;
4026 
4027 public:
4028   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4029     AbstractGangTask("ParPreserveCMReferents"),
4030     _g1h(g1h),
4031     _pss(per_thread_states),
4032     _queues(task_queues),
4033     _terminator(workers, _queues),
4034     _n_workers(workers)
4035   {
4036     g1h->ref_processor_cm()->set_active_mt_degree(workers);
4037   }
4038 
4039   void work(uint worker_id) {
4040     G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4041 
4042     ResourceMark rm;
4043     HandleMark   hm;
4044 
4045     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4046     pss->set_ref_processor(NULL);
4047     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4048 
4049     // Is alive closure
4050     G1AlwaysAliveClosure always_alive(_g1h);
4051 
4052     // Copying keep alive closure. Applied to referent objects that need
4053     // to be copied.
4054     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4055 
4056     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4057 
4058     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4059     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4060 
4061     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4062     // So this must be true - but assert just in case someone decides to
4063     // change the worker ids.
4064     assert(worker_id < limit, "sanity");
4065     assert(!rp->discovery_is_atomic(), "check this code");
4066 
4067     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4068     for (uint idx = worker_id; idx < limit; idx += stride) {
4069       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4070 
4071       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4072       while (iter.has_next()) {
4073         // Since discovery is not atomic for the CM ref processor, we
4074         // can see some null referent objects.
4075         iter.load_ptrs(DEBUG_ONLY(true));
4076         oop ref = iter.obj();
4077 
4078         // This will filter nulls.
4079         if (iter.is_referent_alive()) {
4080           iter.make_referent_alive();
4081         }
4082         iter.move_to_next();
4083       }
4084     }
4085 
4086     // Drain the queue - which may cause stealing
4087     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4088     drain_queue.do_void();
4089     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4090     assert(pss->queue_is_empty(), "should be");
4091   }
4092 };
4093 
4094 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4095   // Any reference objects, in the collection set, that were 'discovered'
4096   // by the CM ref processor should have already been copied (either by
4097   // applying the external root copy closure to the discovered lists, or
4098   // by following an RSet entry).
4099   //
4100   // But some of the referents, that are in the collection set, that these
4101   // reference objects point to may not have been copied: the STW ref
4102   // processor would have seen that the reference object had already
4103   // been 'discovered' and would have skipped discovering the reference,
4104   // but would not have treated the reference object as a regular oop.
4105   // As a result the copy closure would not have been applied to the
4106   // referent object.
4107   //
4108   // We need to explicitly copy these referent objects - the references
4109   // will be processed at the end of remarking.
4110   //
4111   // We also need to do this copying before we process the reference
4112   // objects discovered by the STW ref processor in case one of these
4113   // referents points to another object which is also referenced by an
4114   // object discovered by the STW ref processor.
4115   double preserve_cm_referents_time = 0.0;
4116 
4117   // To avoid spawning task when there is no work to do, check that
4118   // a concurrent cycle is active and that some references have been
4119   // discovered.
4120   if (concurrent_mark()->cm_thread()->during_cycle() &&
4121       ref_processor_cm()->has_discovered_references()) {
4122     double preserve_cm_referents_start = os::elapsedTime();
4123     uint no_of_gc_workers = workers()->active_workers();
4124     G1ParPreserveCMReferentsTask keep_cm_referents(this,
4125                                                    per_thread_states,
4126                                                    no_of_gc_workers,
4127                                                    _task_queues);
4128     workers()->run_task(&keep_cm_referents);
4129     preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4130   }
4131 
4132   g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4133 }
4134 
4135 // Weak Reference processing during an evacuation pause (part 1).
4136 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4137   double ref_proc_start = os::elapsedTime();
4138 
4139   ReferenceProcessor* rp = _ref_processor_stw;
4140   assert(rp->discovery_enabled(), "should have been enabled");
4141 
4142   // Closure to test whether a referent is alive.
4143   G1STWIsAliveClosure is_alive(this);
4144 
4145   // Even when parallel reference processing is enabled, the processing
4146   // of JNI refs is serial and performed serially by the current thread
4147   // rather than by a worker. The following PSS will be used for processing
4148   // JNI refs.
4149 
4150   // Use only a single queue for this PSS.
4151   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4152   pss->set_ref_processor(NULL);
4153   assert(pss->queue_is_empty(), "pre-condition");
4154 
4155   // Keep alive closure.
4156   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4157 
4158   // Serial Complete GC closure
4159   G1STWDrainQueueClosure drain_queue(this, pss);
4160 
4161   // Setup the soft refs policy...
4162   rp->setup_policy(false);
4163 
4164   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4165 
4166   ReferenceProcessorStats stats;
4167   if (!rp->processing_is_mt()) {
4168     // Serial reference processing...
4169     stats = rp->process_discovered_references(&is_alive,
4170                                               &keep_alive,
4171                                               &drain_queue,
4172                                               NULL,
4173                                               pt);
4174   } else {
4175     uint no_of_gc_workers = workers()->active_workers();
4176 
4177     // Parallel reference processing
4178     assert(no_of_gc_workers <= rp->max_num_q(),
4179            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4180            no_of_gc_workers,  rp->max_num_q());
4181 
4182     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4183     stats = rp->process_discovered_references(&is_alive,
4184                                               &keep_alive,
4185                                               &drain_queue,
4186                                               &par_task_executor,
4187                                               pt);
4188   }
4189 
4190   _gc_tracer_stw->report_gc_reference_stats(stats);
4191 
4192   // We have completed copying any necessary live referent objects.
4193   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4194 
4195   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4196   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4197 }
4198 
4199 // Weak Reference processing during an evacuation pause (part 2).
4200 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4201   double ref_enq_start = os::elapsedTime();
4202 
4203   ReferenceProcessor* rp = _ref_processor_stw;
4204   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4205 
4206   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4207 
4208   // Now enqueue any remaining on the discovered lists on to
4209   // the pending list.
4210   if (!rp->processing_is_mt()) {
4211     // Serial reference processing...
4212     rp->enqueue_discovered_references(NULL, pt);
4213   } else {
4214     // Parallel reference enqueueing
4215 
4216     uint n_workers = workers()->active_workers();
4217 
4218     assert(n_workers <= rp->max_num_q(),
4219            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4220            n_workers,  rp->max_num_q());
4221 
4222     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4223     rp->enqueue_discovered_references(&par_task_executor, pt);
4224   }
4225 
4226   rp->verify_no_references_recorded();
4227   assert(!rp->discovery_enabled(), "should have been disabled");
4228 
4229   // If during an initial mark pause we install a pending list head which is not otherwise reachable
4230   // ensure that it is marked in the bitmap for concurrent marking to discover.
4231   if (collector_state()->during_initial_mark_pause()) {
4232     oop pll_head = Universe::reference_pending_list();
4233     if (pll_head != NULL) {
4234       _cm->mark_in_next_bitmap(pll_head);
4235     }
4236   }
4237 
4238   // FIXME
4239   // CM's reference processing also cleans up the string and symbol tables.
4240   // Should we do that here also? We could, but it is a serial operation
4241   // and could significantly increase the pause time.
4242 
4243   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4244   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4245 }
4246 
4247 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4248   double merge_pss_time_start = os::elapsedTime();
4249   per_thread_states->flush();
4250   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4251 }
4252 
4253 void G1CollectedHeap::pre_evacuate_collection_set() {
4254   _expand_heap_after_alloc_failure = true;
4255   _evacuation_failed = false;
4256 
4257   // Disable the hot card cache.
4258   _hot_card_cache->reset_hot_cache_claimed_index();
4259   _hot_card_cache->set_use_cache(false);
4260 
4261   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4262   _preserved_marks_set.assert_empty();
4263 
4264   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4265 
4266   // InitialMark needs claim bits to keep track of the marked-through CLDs.
4267   if (collector_state()->during_initial_mark_pause()) {
4268     double start_clear_claimed_marks = os::elapsedTime();
4269 
4270     ClassLoaderDataGraph::clear_claimed_marks();
4271 
4272     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4273     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4274   }
4275 }
4276 
4277 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4278   // Should G1EvacuationFailureALot be in effect for this GC?
4279   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4280 
4281   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4282 
4283   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4284 
4285   double start_par_time_sec = os::elapsedTime();
4286   double end_par_time_sec;
4287 
4288   {
4289     const uint n_workers = workers()->active_workers();
4290     G1RootProcessor root_processor(this, n_workers);
4291     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4292 
4293     print_termination_stats_hdr();
4294 
4295     workers()->run_task(&g1_par_task);
4296     end_par_time_sec = os::elapsedTime();
4297 
4298     // Closing the inner scope will execute the destructor
4299     // for the G1RootProcessor object. We record the current
4300     // elapsed time before closing the scope so that time
4301     // taken for the destructor is NOT included in the
4302     // reported parallel time.
4303   }
4304 
4305   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4306   phase_times->record_par_time(par_time_ms);
4307 
4308   double code_root_fixup_time_ms =
4309         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4310   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4311 }
4312 
4313 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4314   // Process any discovered reference objects - we have
4315   // to do this _before_ we retire the GC alloc regions
4316   // as we may have to copy some 'reachable' referent
4317   // objects (and their reachable sub-graphs) that were
4318   // not copied during the pause.
4319   if (g1_policy()->should_process_references()) {
4320     preserve_cm_referents(per_thread_states);
4321     process_discovered_references(per_thread_states);
4322   } else {
4323     ref_processor_stw()->verify_no_references_recorded();
4324   }
4325 
4326   G1STWIsAliveClosure is_alive(this);
4327   G1KeepAliveClosure keep_alive(this);
4328 
4329   {
4330     double start = os::elapsedTime();
4331 
4332     WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4333 
4334     double time_ms = (os::elapsedTime() - start) * 1000.0;
4335     g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4336   }
4337 
4338   if (G1StringDedup::is_enabled()) {
4339     double fixup_start = os::elapsedTime();
4340 
4341     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4342 
4343     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4344     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4345   }
4346 
4347   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4348 
4349   if (evacuation_failed()) {
4350     restore_after_evac_failure();
4351 
4352     // Reset the G1EvacuationFailureALot counters and flags
4353     // Note: the values are reset only when an actual
4354     // evacuation failure occurs.
4355     NOT_PRODUCT(reset_evacuation_should_fail();)
4356   }
4357 
4358   _preserved_marks_set.assert_empty();
4359 
4360   // Enqueue any remaining references remaining on the STW
4361   // reference processor's discovered lists. We need to do
4362   // this after the card table is cleaned (and verified) as
4363   // the act of enqueueing entries on to the pending list
4364   // will log these updates (and dirty their associated
4365   // cards). We need these updates logged to update any
4366   // RSets.
4367   if (g1_policy()->should_process_references()) {
4368     enqueue_discovered_references(per_thread_states);
4369   } else {
4370     g1_policy()->phase_times()->record_ref_enq_time(0);
4371   }
4372 
4373   _allocator->release_gc_alloc_regions(evacuation_info);
4374 
4375   merge_per_thread_state_info(per_thread_states);
4376 
4377   // Reset and re-enable the hot card cache.
4378   // Note the counts for the cards in the regions in the
4379   // collection set are reset when the collection set is freed.
4380   _hot_card_cache->reset_hot_cache();
4381   _hot_card_cache->set_use_cache(true);
4382 
4383   purge_code_root_memory();
4384 
4385   redirty_logged_cards();
4386 #if COMPILER2_OR_JVMCI
4387   double start = os::elapsedTime();
4388   DerivedPointerTable::update_pointers();
4389   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4390 #endif
4391   g1_policy()->print_age_table();
4392 }
4393 
4394 void G1CollectedHeap::record_obj_copy_mem_stats() {
4395   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4396 
4397   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4398                                                create_g1_evac_summary(&_old_evac_stats));
4399 }
4400 
4401 void G1CollectedHeap::free_region(HeapRegion* hr,
4402                                   FreeRegionList* free_list,
4403                                   bool skip_remset,
4404                                   bool skip_hot_card_cache,
4405                                   bool locked) {
4406   assert(!hr->is_free(), "the region should not be free");
4407   assert(!hr->is_empty(), "the region should not be empty");
4408   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4409   assert(free_list != NULL, "pre-condition");
4410 
4411   if (G1VerifyBitmaps) {
4412     MemRegion mr(hr->bottom(), hr->end());
4413     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4414   }
4415 
4416   // Clear the card counts for this region.
4417   // Note: we only need to do this if the region is not young
4418   // (since we don't refine cards in young regions).
4419   if (!skip_hot_card_cache && !hr->is_young()) {
4420     _hot_card_cache->reset_card_counts(hr);
4421   }
4422   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4423   free_list->add_ordered(hr);
4424 }
4425 
4426 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4427                                             FreeRegionList* free_list,
4428                                             bool skip_remset) {
4429   assert(hr->is_humongous(), "this is only for humongous regions");
4430   assert(free_list != NULL, "pre-condition");
4431   hr->clear_humongous();
4432   free_region(hr, free_list, skip_remset);
4433 }
4434 
4435 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4436                                            const uint humongous_regions_removed) {
4437   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4438     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4439     _old_set.bulk_remove(old_regions_removed);
4440     _humongous_set.bulk_remove(humongous_regions_removed);
4441   }
4442 
4443 }
4444 
4445 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4446   assert(list != NULL, "list can't be null");
4447   if (!list->is_empty()) {
4448     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4449     _hrm.insert_list_into_free_list(list);
4450   }
4451 }
4452 
4453 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4454   decrease_used(bytes);
4455 }
4456 
4457 class G1ParScrubRemSetTask: public AbstractGangTask {
4458 protected:
4459   G1RemSet* _g1rs;
4460   HeapRegionClaimer _hrclaimer;
4461 
4462 public:
4463   G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4464     AbstractGangTask("G1 ScrubRS"),
4465     _g1rs(g1_rs),
4466     _hrclaimer(num_workers) {
4467   }
4468 
4469   void work(uint worker_id) {
4470     _g1rs->scrub(worker_id, &_hrclaimer);
4471   }
4472 };
4473 
4474 void G1CollectedHeap::scrub_rem_set() {
4475   uint num_workers = workers()->active_workers();
4476   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4477   workers()->run_task(&g1_par_scrub_rs_task);
4478 }
4479 
4480 class G1FreeCollectionSetTask : public AbstractGangTask {
4481 private:
4482 
4483   // Closure applied to all regions in the collection set to do work that needs to
4484   // be done serially in a single thread.
4485   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4486   private:
4487     EvacuationInfo* _evacuation_info;
4488     const size_t* _surviving_young_words;
4489 
4490     // Bytes used in successfully evacuated regions before the evacuation.
4491     size_t _before_used_bytes;
4492     // Bytes used in unsucessfully evacuated regions before the evacuation
4493     size_t _after_used_bytes;
4494 
4495     size_t _bytes_allocated_in_old_since_last_gc;
4496 
4497     size_t _failure_used_words;
4498     size_t _failure_waste_words;
4499 
4500     FreeRegionList _local_free_list;
4501   public:
4502     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4503       HeapRegionClosure(),
4504       _evacuation_info(evacuation_info),
4505       _surviving_young_words(surviving_young_words),
4506       _before_used_bytes(0),
4507       _after_used_bytes(0),
4508       _bytes_allocated_in_old_since_last_gc(0),
4509       _failure_used_words(0),
4510       _failure_waste_words(0),
4511       _local_free_list("Local Region List for CSet Freeing") {
4512     }
4513 
4514     virtual bool do_heap_region(HeapRegion* r) {
4515       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4516 
4517       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4518       g1h->clear_in_cset(r);
4519 
4520       if (r->is_young()) {
4521         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4522                "Young index %d is wrong for region %u of type %s with %u young regions",
4523                r->young_index_in_cset(),
4524                r->hrm_index(),
4525                r->get_type_str(),
4526                g1h->collection_set()->young_region_length());
4527         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4528         r->record_surv_words_in_group(words_survived);
4529       }
4530 
4531       if (!r->evacuation_failed()) {
4532         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4533         _before_used_bytes += r->used();
4534         g1h->free_region(r,
4535                          &_local_free_list,
4536                          true, /* skip_remset */
4537                          true, /* skip_hot_card_cache */
4538                          true  /* locked */);
4539       } else {
4540         r->uninstall_surv_rate_group();
4541         r->set_young_index_in_cset(-1);
4542         r->set_evacuation_failed(false);
4543         // When moving a young gen region to old gen, we "allocate" that whole region
4544         // there. This is in addition to any already evacuated objects. Notify the
4545         // policy about that.
4546         // Old gen regions do not cause an additional allocation: both the objects
4547         // still in the region and the ones already moved are accounted for elsewhere.
4548         if (r->is_young()) {
4549           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4550         }
4551         // The region is now considered to be old.
4552         r->set_old();
4553         // Do some allocation statistics accounting. Regions that failed evacuation
4554         // are always made old, so there is no need to update anything in the young
4555         // gen statistics, but we need to update old gen statistics.
4556         size_t used_words = r->marked_bytes() / HeapWordSize;
4557 
4558         _failure_used_words += used_words;
4559         _failure_waste_words += HeapRegion::GrainWords - used_words;
4560 
4561         g1h->old_set_add(r);
4562         _after_used_bytes += r->used();
4563       }
4564       return false;
4565     }
4566 
4567     void complete_work() {
4568       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4569 
4570       _evacuation_info->set_regions_freed(_local_free_list.length());
4571       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4572 
4573       g1h->prepend_to_freelist(&_local_free_list);
4574       g1h->decrement_summary_bytes(_before_used_bytes);
4575 
4576       G1Policy* policy = g1h->g1_policy();
4577       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4578 
4579       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4580     }
4581   };
4582 
4583   G1CollectionSet* _collection_set;
4584   G1SerialFreeCollectionSetClosure _cl;
4585   const size_t* _surviving_young_words;
4586 
4587   size_t _rs_lengths;
4588 
4589   volatile jint _serial_work_claim;
4590 
4591   struct WorkItem {
4592     uint region_idx;
4593     bool is_young;
4594     bool evacuation_failed;
4595 
4596     WorkItem(HeapRegion* r) {
4597       region_idx = r->hrm_index();
4598       is_young = r->is_young();
4599       evacuation_failed = r->evacuation_failed();
4600     }
4601   };
4602 
4603   volatile size_t _parallel_work_claim;
4604   size_t _num_work_items;
4605   WorkItem* _work_items;
4606 
4607   void do_serial_work() {
4608     // Need to grab the lock to be allowed to modify the old region list.
4609     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4610     _collection_set->iterate(&_cl);
4611   }
4612 
4613   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4614     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4615 
4616     HeapRegion* r = g1h->region_at(region_idx);
4617     assert(!g1h->is_on_master_free_list(r), "sanity");
4618 
4619     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4620 
4621     if (!is_young) {
4622       g1h->_hot_card_cache->reset_card_counts(r);
4623     }
4624 
4625     if (!evacuation_failed) {
4626       r->rem_set()->clear_locked();
4627     }
4628   }
4629 
4630   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4631   private:
4632     size_t _cur_idx;
4633     WorkItem* _work_items;
4634   public:
4635     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4636 
4637     virtual bool do_heap_region(HeapRegion* r) {
4638       _work_items[_cur_idx++] = WorkItem(r);
4639       return false;
4640     }
4641   };
4642 
4643   void prepare_work() {
4644     G1PrepareFreeCollectionSetClosure cl(_work_items);
4645     _collection_set->iterate(&cl);
4646   }
4647 
4648   void complete_work() {
4649     _cl.complete_work();
4650 
4651     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4652     policy->record_max_rs_lengths(_rs_lengths);
4653     policy->cset_regions_freed();
4654   }
4655 public:
4656   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4657     AbstractGangTask("G1 Free Collection Set"),
4658     _cl(evacuation_info, surviving_young_words),
4659     _collection_set(collection_set),
4660     _surviving_young_words(surviving_young_words),
4661     _serial_work_claim(0),
4662     _rs_lengths(0),
4663     _parallel_work_claim(0),
4664     _num_work_items(collection_set->region_length()),
4665     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4666     prepare_work();
4667   }
4668 
4669   ~G1FreeCollectionSetTask() {
4670     complete_work();
4671     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4672   }
4673 
4674   // Chunk size for work distribution. The chosen value has been determined experimentally
4675   // to be a good tradeoff between overhead and achievable parallelism.
4676   static uint chunk_size() { return 32; }
4677 
4678   virtual void work(uint worker_id) {
4679     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4680 
4681     // Claim serial work.
4682     if (_serial_work_claim == 0) {
4683       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4684       if (value == 0) {
4685         double serial_time = os::elapsedTime();
4686         do_serial_work();
4687         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4688       }
4689     }
4690 
4691     // Start parallel work.
4692     double young_time = 0.0;
4693     bool has_young_time = false;
4694     double non_young_time = 0.0;
4695     bool has_non_young_time = false;
4696 
4697     while (true) {
4698       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4699       size_t cur = end - chunk_size();
4700 
4701       if (cur >= _num_work_items) {
4702         break;
4703       }
4704 
4705       double start_time = os::elapsedTime();
4706 
4707       end = MIN2(end, _num_work_items);
4708 
4709       for (; cur < end; cur++) {
4710         bool is_young = _work_items[cur].is_young;
4711 
4712         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4713 
4714         double end_time = os::elapsedTime();
4715         double time_taken = end_time - start_time;
4716         if (is_young) {
4717           young_time += time_taken;
4718           has_young_time = true;
4719         } else {
4720           non_young_time += time_taken;
4721           has_non_young_time = true;
4722         }
4723         start_time = end_time;
4724       }
4725     }
4726 
4727     if (has_young_time) {
4728       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4729     }
4730     if (has_non_young_time) {
4731       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4732     }
4733   }
4734 };
4735 
4736 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4737   _eden.clear();
4738 
4739   double free_cset_start_time = os::elapsedTime();
4740 
4741   {
4742     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4743     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4744 
4745     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4746 
4747     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4748                         cl.name(),
4749                         num_workers,
4750                         _collection_set.region_length());
4751     workers()->run_task(&cl, num_workers);
4752   }
4753   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4754 
4755   collection_set->clear();
4756 }
4757 
4758 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4759  private:
4760   FreeRegionList* _free_region_list;
4761   HeapRegionSet* _proxy_set;
4762   uint _humongous_objects_reclaimed;
4763   uint _humongous_regions_reclaimed;
4764   size_t _freed_bytes;
4765  public:
4766 
4767   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4768     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4769   }
4770 
4771   virtual bool do_heap_region(HeapRegion* r) {
4772     if (!r->is_starts_humongous()) {
4773       return false;
4774     }
4775 
4776     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4777 
4778     oop obj = (oop)r->bottom();
4779     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4780 
4781     // The following checks whether the humongous object is live are sufficient.
4782     // The main additional check (in addition to having a reference from the roots
4783     // or the young gen) is whether the humongous object has a remembered set entry.
4784     //
4785     // A humongous object cannot be live if there is no remembered set for it
4786     // because:
4787     // - there can be no references from within humongous starts regions referencing
4788     // the object because we never allocate other objects into them.
4789     // (I.e. there are no intra-region references that may be missed by the
4790     // remembered set)
4791     // - as soon there is a remembered set entry to the humongous starts region
4792     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4793     // until the end of a concurrent mark.
4794     //
4795     // It is not required to check whether the object has been found dead by marking
4796     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4797     // all objects allocated during that time are considered live.
4798     // SATB marking is even more conservative than the remembered set.
4799     // So if at this point in the collection there is no remembered set entry,
4800     // nobody has a reference to it.
4801     // At the start of collection we flush all refinement logs, and remembered sets
4802     // are completely up-to-date wrt to references to the humongous object.
4803     //
4804     // Other implementation considerations:
4805     // - never consider object arrays at this time because they would pose
4806     // considerable effort for cleaning up the the remembered sets. This is
4807     // required because stale remembered sets might reference locations that
4808     // are currently allocated into.
4809     uint region_idx = r->hrm_index();
4810     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4811         !r->rem_set()->is_empty()) {
4812       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",
4813                                region_idx,
4814                                (size_t)obj->size() * HeapWordSize,
4815                                p2i(r->bottom()),
4816                                r->rem_set()->occupied(),
4817                                r->rem_set()->strong_code_roots_list_length(),
4818                                next_bitmap->is_marked(r->bottom()),
4819                                g1h->is_humongous_reclaim_candidate(region_idx),
4820                                obj->is_typeArray()
4821                               );
4822       return false;
4823     }
4824 
4825     guarantee(obj->is_typeArray(),
4826               "Only eagerly reclaiming type arrays is supported, but the object "
4827               PTR_FORMAT " is not.", p2i(r->bottom()));
4828 
4829     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",
4830                              region_idx,
4831                              (size_t)obj->size() * HeapWordSize,
4832                              p2i(r->bottom()),
4833                              r->rem_set()->occupied(),
4834                              r->rem_set()->strong_code_roots_list_length(),
4835                              next_bitmap->is_marked(r->bottom()),
4836                              g1h->is_humongous_reclaim_candidate(region_idx),
4837                              obj->is_typeArray()
4838                             );
4839 
4840     // Need to clear mark bit of the humongous object if already set.
4841     if (next_bitmap->is_marked(r->bottom())) {
4842       next_bitmap->clear(r->bottom());
4843     }
4844     _humongous_objects_reclaimed++;
4845     do {
4846       HeapRegion* next = g1h->next_region_in_humongous(r);
4847       _freed_bytes += r->used();
4848       r->set_containing_set(NULL);
4849       _humongous_regions_reclaimed++;
4850       g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4851       r = next;
4852     } while (r != NULL);
4853 
4854     return false;
4855   }
4856 
4857   uint humongous_objects_reclaimed() {
4858     return _humongous_objects_reclaimed;
4859   }
4860 
4861   uint humongous_regions_reclaimed() {
4862     return _humongous_regions_reclaimed;
4863   }
4864 
4865   size_t bytes_freed() const {
4866     return _freed_bytes;
4867   }
4868 };
4869 
4870 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4871   assert_at_safepoint(true);
4872 
4873   if (!G1EagerReclaimHumongousObjects ||
4874       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4875     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4876     return;
4877   }
4878 
4879   double start_time = os::elapsedTime();
4880 
4881   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4882 
4883   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4884   heap_region_iterate(&cl);
4885 
4886   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4887 
4888   G1HRPrinter* hrp = hr_printer();
4889   if (hrp->is_active()) {
4890     FreeRegionListIterator iter(&local_cleanup_list);
4891     while (iter.more_available()) {
4892       HeapRegion* hr = iter.get_next();
4893       hrp->cleanup(hr);
4894     }
4895   }
4896 
4897   prepend_to_freelist(&local_cleanup_list);
4898   decrement_summary_bytes(cl.bytes_freed());
4899 
4900   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4901                                                                     cl.humongous_objects_reclaimed());
4902 }
4903 
4904 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4905 public:
4906   virtual bool do_heap_region(HeapRegion* r) {
4907     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4908     G1CollectedHeap::heap()->clear_in_cset(r);
4909     r->set_young_index_in_cset(-1);
4910     return false;
4911   }
4912 };
4913 
4914 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4915   G1AbandonCollectionSetClosure cl;
4916   collection_set->iterate(&cl);
4917 
4918   collection_set->clear();
4919   collection_set->stop_incremental_building();
4920 }
4921 
4922 void G1CollectedHeap::set_free_regions_coming() {
4923   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4924 
4925   assert(!free_regions_coming(), "pre-condition");
4926   _free_regions_coming = true;
4927 }
4928 
4929 void G1CollectedHeap::reset_free_regions_coming() {
4930   assert(free_regions_coming(), "pre-condition");
4931 
4932   {
4933     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4934     _free_regions_coming = false;
4935     SecondaryFreeList_lock->notify_all();
4936   }
4937 
4938   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4939 }
4940 
4941 void G1CollectedHeap::wait_while_free_regions_coming() {
4942   // Most of the time we won't have to wait, so let's do a quick test
4943   // first before we take the lock.
4944   if (!free_regions_coming()) {
4945     return;
4946   }
4947 
4948   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4949 
4950   {
4951     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4952     while (free_regions_coming()) {
4953       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4954     }
4955   }
4956 
4957   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
4958 }
4959 
4960 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4961   return _allocator->is_retained_old_region(hr);
4962 }
4963 
4964 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4965   _eden.add(hr);
4966   _g1_policy->set_region_eden(hr);
4967 }
4968 
4969 #ifdef ASSERT
4970 
4971 class NoYoungRegionsClosure: public HeapRegionClosure {
4972 private:
4973   bool _success;
4974 public:
4975   NoYoungRegionsClosure() : _success(true) { }
4976   bool do_heap_region(HeapRegion* r) {
4977     if (r->is_young()) {
4978       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4979                             p2i(r->bottom()), p2i(r->end()));
4980       _success = false;
4981     }
4982     return false;
4983   }
4984   bool success() { return _success; }
4985 };
4986 
4987 bool G1CollectedHeap::check_young_list_empty() {
4988   bool ret = (young_regions_count() == 0);
4989 
4990   NoYoungRegionsClosure closure;
4991   heap_region_iterate(&closure);
4992   ret = ret && closure.success();
4993 
4994   return ret;
4995 }
4996 
4997 #endif // ASSERT
4998 
4999 class TearDownRegionSetsClosure : public HeapRegionClosure {
5000 private:
5001   HeapRegionSet *_old_set;
5002 
5003 public:
5004   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5005 
5006   bool do_heap_region(HeapRegion* r) {
5007     if (r->is_old()) {
5008       _old_set->remove(r);
5009     } else if(r->is_young()) {
5010       r->uninstall_surv_rate_group();
5011     } else {
5012       // We ignore free regions, we'll empty the free list afterwards.
5013       // We ignore humongous regions, we're not tearing down the
5014       // humongous regions set.
5015       assert(r->is_free() || r->is_humongous(),
5016              "it cannot be another type");
5017     }
5018     return false;
5019   }
5020 
5021   ~TearDownRegionSetsClosure() {
5022     assert(_old_set->is_empty(), "post-condition");
5023   }
5024 };
5025 
5026 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5027   assert_at_safepoint(true /* should_be_vm_thread */);
5028 
5029   if (!free_list_only) {
5030     TearDownRegionSetsClosure cl(&_old_set);
5031     heap_region_iterate(&cl);
5032 
5033     // Note that emptying the _young_list is postponed and instead done as
5034     // the first step when rebuilding the regions sets again. The reason for
5035     // this is that during a full GC string deduplication needs to know if
5036     // a collected region was young or old when the full GC was initiated.
5037   }
5038   _hrm.remove_all_free_regions();
5039 }
5040 
5041 void G1CollectedHeap::increase_used(size_t bytes) {
5042   _summary_bytes_used += bytes;
5043 }
5044 
5045 void G1CollectedHeap::decrease_used(size_t bytes) {
5046   assert(_summary_bytes_used >= bytes,
5047          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5048          _summary_bytes_used, bytes);
5049   _summary_bytes_used -= bytes;
5050 }
5051 
5052 void G1CollectedHeap::set_used(size_t bytes) {
5053   _summary_bytes_used = bytes;
5054 }
5055 
5056 class RebuildRegionSetsClosure : public HeapRegionClosure {
5057 private:
5058   bool            _free_list_only;
5059   HeapRegionSet*   _old_set;
5060   HeapRegionManager*   _hrm;
5061   size_t          _total_used;
5062 
5063 public:
5064   RebuildRegionSetsClosure(bool free_list_only,
5065                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5066     _free_list_only(free_list_only),
5067     _old_set(old_set), _hrm(hrm), _total_used(0) {
5068     assert(_hrm->num_free_regions() == 0, "pre-condition");
5069     if (!free_list_only) {
5070       assert(_old_set->is_empty(), "pre-condition");
5071     }
5072   }
5073 
5074   bool do_heap_region(HeapRegion* r) {
5075     if (r->is_empty()) {
5076       // Add free regions to the free list
5077       r->set_free();
5078       r->set_allocation_context(AllocationContext::system());
5079       _hrm->insert_into_free_list(r);
5080     } else if (!_free_list_only) {
5081 
5082       if (r->is_humongous()) {
5083         // We ignore humongous regions. We left the humongous set unchanged.
5084       } else {
5085         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5086         // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5087         r->move_to_old();
5088         _old_set->add(r);
5089       }
5090       _total_used += r->used();
5091     }
5092 
5093     return false;
5094   }
5095 
5096   size_t total_used() {
5097     return _total_used;
5098   }
5099 };
5100 
5101 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5102   assert_at_safepoint(true /* should_be_vm_thread */);
5103 
5104   if (!free_list_only) {
5105     _eden.clear();
5106     _survivor.clear();
5107   }
5108 
5109   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5110   heap_region_iterate(&cl);
5111 
5112   if (!free_list_only) {
5113     set_used(cl.total_used());
5114     if (_archive_allocator != NULL) {
5115       _archive_allocator->clear_used();
5116     }
5117   }
5118   assert(used_unlocked() == recalculate_used(),
5119          "inconsistent used_unlocked(), "
5120          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5121          used_unlocked(), recalculate_used());
5122 }
5123 
5124 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5125   HeapRegion* hr = heap_region_containing(p);
5126   return hr->is_in(p);
5127 }
5128 
5129 // Methods for the mutator alloc region
5130 
5131 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5132                                                       bool force) {
5133   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5134   bool should_allocate = g1_policy()->should_allocate_mutator_region();
5135   if (force || should_allocate) {
5136     HeapRegion* new_alloc_region = new_region(word_size,
5137                                               false /* is_old */,
5138                                               false /* do_expand */);
5139     if (new_alloc_region != NULL) {
5140       set_region_short_lived_locked(new_alloc_region);
5141       _hr_printer.alloc(new_alloc_region, !should_allocate);
5142       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5143       return new_alloc_region;
5144     }
5145   }
5146   return NULL;
5147 }
5148 
5149 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5150                                                   size_t allocated_bytes) {
5151   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5152   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5153 
5154   collection_set()->add_eden_region(alloc_region);
5155   increase_used(allocated_bytes);
5156   _hr_printer.retire(alloc_region);
5157   // We update the eden sizes here, when the region is retired,
5158   // instead of when it's allocated, since this is the point that its
5159   // used space has been recored in _summary_bytes_used.
5160   g1mm()->update_eden_size();
5161 }
5162 
5163 // Methods for the GC alloc regions
5164 
5165 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5166   if (dest.is_old()) {
5167     return true;
5168   } else {
5169     return survivor_regions_count() < g1_policy()->max_survivor_regions();
5170   }
5171 }
5172 
5173 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5174   assert(FreeList_lock->owned_by_self(), "pre-condition");
5175 
5176   if (!has_more_regions(dest)) {
5177     return NULL;
5178   }
5179 
5180   const bool is_survivor = dest.is_young();
5181 
5182   HeapRegion* new_alloc_region = new_region(word_size,
5183                                             !is_survivor,
5184                                             true /* do_expand */);
5185   if (new_alloc_region != NULL) {
5186     // We really only need to do this for old regions given that we
5187     // should never scan survivors. But it doesn't hurt to do it
5188     // for survivors too.
5189     new_alloc_region->record_timestamp();
5190     if (is_survivor) {
5191       new_alloc_region->set_survivor();
5192       _survivor.add(new_alloc_region);
5193       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5194     } else {
5195       new_alloc_region->set_old();
5196       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5197     }
5198     _hr_printer.alloc(new_alloc_region);
5199     bool during_im = collector_state()->during_initial_mark_pause();
5200     new_alloc_region->note_start_of_copying(during_im);
5201     return new_alloc_region;
5202   }
5203   return NULL;
5204 }
5205 
5206 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5207                                              size_t allocated_bytes,
5208                                              InCSetState dest) {
5209   bool during_im = collector_state()->during_initial_mark_pause();
5210   alloc_region->note_end_of_copying(during_im);
5211   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5212   if (dest.is_old()) {
5213     _old_set.add(alloc_region);
5214   }
5215   _hr_printer.retire(alloc_region);
5216 }
5217 
5218 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5219   bool expanded = false;
5220   uint index = _hrm.find_highest_free(&expanded);
5221 
5222   if (index != G1_NO_HRM_INDEX) {
5223     if (expanded) {
5224       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5225                                 HeapRegion::GrainWords * HeapWordSize);
5226     }
5227     _hrm.allocate_free_regions_starting_at(index, 1);
5228     return region_at(index);
5229   }
5230   return NULL;
5231 }
5232 
5233 // Optimized nmethod scanning
5234 
5235 class RegisterNMethodOopClosure: public OopClosure {
5236   G1CollectedHeap* _g1h;
5237   nmethod* _nm;
5238 
5239   template <class T> void do_oop_work(T* p) {
5240     T heap_oop = oopDesc::load_heap_oop(p);
5241     if (!oopDesc::is_null(heap_oop)) {
5242       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5243       HeapRegion* hr = _g1h->heap_region_containing(obj);
5244       assert(!hr->is_continues_humongous(),
5245              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5246              " starting at " HR_FORMAT,
5247              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5248 
5249       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5250       hr->add_strong_code_root_locked(_nm);
5251     }
5252   }
5253 
5254 public:
5255   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5256     _g1h(g1h), _nm(nm) {}
5257 
5258   void do_oop(oop* p)       { do_oop_work(p); }
5259   void do_oop(narrowOop* p) { do_oop_work(p); }
5260 };
5261 
5262 class UnregisterNMethodOopClosure: public OopClosure {
5263   G1CollectedHeap* _g1h;
5264   nmethod* _nm;
5265 
5266   template <class T> void do_oop_work(T* p) {
5267     T heap_oop = oopDesc::load_heap_oop(p);
5268     if (!oopDesc::is_null(heap_oop)) {
5269       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5270       HeapRegion* hr = _g1h->heap_region_containing(obj);
5271       assert(!hr->is_continues_humongous(),
5272              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5273              " starting at " HR_FORMAT,
5274              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5275 
5276       hr->remove_strong_code_root(_nm);
5277     }
5278   }
5279 
5280 public:
5281   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5282     _g1h(g1h), _nm(nm) {}
5283 
5284   void do_oop(oop* p)       { do_oop_work(p); }
5285   void do_oop(narrowOop* p) { do_oop_work(p); }
5286 };
5287 
5288 // Returns true if the reference points to an object that
5289 // can move in an incremental collection.
5290 bool G1CollectedHeap::is_scavengable(oop obj) {
5291   HeapRegion* hr = heap_region_containing(obj);
5292   return !hr->is_pinned();
5293 }
5294 
5295 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5296   guarantee(nm != NULL, "sanity");
5297   RegisterNMethodOopClosure reg_cl(this, nm);
5298   nm->oops_do(&reg_cl);
5299 }
5300 
5301 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5302   guarantee(nm != NULL, "sanity");
5303   UnregisterNMethodOopClosure reg_cl(this, nm);
5304   nm->oops_do(&reg_cl, true);
5305 }
5306 
5307 void G1CollectedHeap::purge_code_root_memory() {
5308   double purge_start = os::elapsedTime();
5309   G1CodeRootSet::purge();
5310   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5311   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5312 }
5313 
5314 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5315   G1CollectedHeap* _g1h;
5316 
5317 public:
5318   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5319     _g1h(g1h) {}
5320 
5321   void do_code_blob(CodeBlob* cb) {
5322     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5323     if (nm == NULL) {
5324       return;
5325     }
5326 
5327     if (ScavengeRootsInCode) {
5328       _g1h->register_nmethod(nm);
5329     }
5330   }
5331 };
5332 
5333 void G1CollectedHeap::rebuild_strong_code_roots() {
5334   RebuildStrongCodeRootClosure blob_cl(this);
5335   CodeCache::blobs_do(&blob_cl);
5336 }
5337 
5338 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5339   GrowableArray<GCMemoryManager*> memory_managers(2);
5340   memory_managers.append(&_memory_manager);
5341   memory_managers.append(&_full_gc_memory_manager);
5342   return memory_managers;
5343 }
5344 
5345 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5346   GrowableArray<MemoryPool*> memory_pools(3);
5347   memory_pools.append(_eden_pool);
5348   memory_pools.append(_survivor_pool);
5349   memory_pools.append(_old_pool);
5350   return memory_pools;
5351 }