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/g1StringDedup.hpp"
  56 #include "gc/g1/g1YCTypes.hpp"
  57 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  58 #include "gc/g1/heapRegion.inline.hpp"
  59 #include "gc/g1/heapRegionRemSet.hpp"
  60 #include "gc/g1/heapRegionSet.inline.hpp"
  61 #include "gc/g1/vm_operations_g1.hpp"
  62 #include "gc/shared/adaptiveSizePolicy.hpp"
  63 #include "gc/shared/gcHeapSummary.hpp"
  64 #include "gc/shared/gcId.hpp"
  65 #include "gc/shared/gcLocker.inline.hpp"
  66 #include "gc/shared/gcTimer.hpp"
  67 #include "gc/shared/gcTrace.hpp"
  68 #include "gc/shared/gcTraceTime.inline.hpp"
  69 #include "gc/shared/generationSpec.hpp"
  70 #include "gc/shared/isGCActiveMark.hpp"
  71 #include "gc/shared/preservedMarks.inline.hpp"
  72 #include "gc/shared/suspendibleThreadSet.hpp"
  73 #include "gc/shared/referenceProcessor.inline.hpp"
  74 #include "gc/shared/taskqueue.inline.hpp"
  75 #include "gc/shared/weakProcessor.hpp"
  76 #include "logging/log.hpp"
  77 #include "memory/allocation.hpp"
  78 #include "memory/iterator.hpp"
  79 #include "memory/resourceArea.hpp"
  80 #include "oops/oop.inline.hpp"
  81 #include "prims/resolvedMethodTable.hpp"
  82 #include "runtime/atomic.hpp"
  83 #include "runtime/init.hpp"
  84 #include "runtime/orderAccess.inline.hpp"
  85 #include "runtime/threadSMR.hpp"
  86 #include "runtime/vmThread.hpp"
  87 #include "utilities/align.hpp"
  88 #include "utilities/globalDefinitions.hpp"
  89 #include "utilities/stack.inline.hpp"
  90 
  91 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  92 
  93 // INVARIANTS/NOTES
  94 //
  95 // All allocation activity covered by the G1CollectedHeap interface is
  96 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  97 // and allocate_new_tlab, which are the "entry" points to the
  98 // allocation code from the rest of the JVM.  (Note that this does not
  99 // apply to TLAB allocation, which is not part of this interface: it
 100 // is done by clients of this interface.)
 101 
 102 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 103  private:
 104   size_t _num_dirtied;
 105   G1CollectedHeap* _g1h;
 106   G1CardTable* _g1_ct;
 107 
 108   HeapRegion* region_for_card(jbyte* card_ptr) const {
 109     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
 110   }
 111 
 112   bool will_become_free(HeapRegion* hr) const {
 113     // A region will be freed by free_collection_set if the region is in the
 114     // collection set and has not had an evacuation failure.
 115     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 116   }
 117 
 118  public:
 119   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 120     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
 121 
 122   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 123     HeapRegion* hr = region_for_card(card_ptr);
 124 
 125     // Should only dirty cards in regions that won't be freed.
 126     if (!will_become_free(hr)) {
 127       *card_ptr = G1CardTable::dirty_card_val();
 128       _num_dirtied++;
 129     }
 130 
 131     return true;
 132   }
 133 
 134   size_t num_dirtied()   const { return _num_dirtied; }
 135 };
 136 
 137 
 138 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 139   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 140 }
 141 
 142 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 143   // The from card cache is not the memory that is actually committed. So we cannot
 144   // take advantage of the zero_filled parameter.
 145   reset_from_card_cache(start_idx, num_regions);
 146 }
 147 
 148 
 149 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 150                                              MemRegion mr) {
 151   return new HeapRegion(hrs_index, bot(), mr);
 152 }
 153 
 154 // Private methods.
 155 
 156 HeapRegion*
 157 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 158   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 159   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 160     if (!_secondary_free_list.is_empty()) {
 161       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 162                                       "secondary_free_list has %u entries",
 163                                       _secondary_free_list.length());
 164       // It looks as if there are free regions available on the
 165       // secondary_free_list. Let's move them to the free_list and try
 166       // again to allocate from it.
 167       append_secondary_free_list();
 168 
 169       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 170              "empty we should have moved at least one entry to the free_list");
 171       HeapRegion* res = _hrm.allocate_free_region(is_old);
 172       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 173                                       "allocated " HR_FORMAT " from secondary_free_list",
 174                                       HR_FORMAT_PARAMS(res));
 175       return res;
 176     }
 177 
 178     // Wait here until we get notified either when (a) there are no
 179     // more free regions coming or (b) some regions have been moved on
 180     // the secondary_free_list.
 181     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 182   }
 183 
 184   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 185                                   "could not allocate from secondary_free_list");
 186   return NULL;
 187 }
 188 
 189 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 190   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 191          "the only time we use this to allocate a humongous region is "
 192          "when we are allocating a single humongous region");
 193 
 194   HeapRegion* res;
 195   if (G1StressConcRegionFreeing) {
 196     if (!_secondary_free_list.is_empty()) {
 197       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 198                                       "forced to look at the secondary_free_list");
 199       res = new_region_try_secondary_free_list(is_old);
 200       if (res != NULL) {
 201         return res;
 202       }
 203     }
 204   }
 205 
 206   res = _hrm.allocate_free_region(is_old);
 207 
 208   if (res == NULL) {
 209     log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 210                                     "res == NULL, trying the secondary_free_list");
 211     res = new_region_try_secondary_free_list(is_old);
 212   }
 213   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 214     // Currently, only attempts to allocate GC alloc regions set
 215     // do_expand to true. So, we should only reach here during a
 216     // safepoint. If this assumption changes we might have to
 217     // reconsider the use of _expand_heap_after_alloc_failure.
 218     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 219 
 220     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 221                               word_size * HeapWordSize);
 222 
 223     if (expand(word_size * HeapWordSize)) {
 224       // Given that expand() succeeded in expanding the heap, and we
 225       // always expand the heap by an amount aligned to the heap
 226       // region size, the free list should in theory not be empty.
 227       // In either case allocate_free_region() will check for NULL.
 228       res = _hrm.allocate_free_region(is_old);
 229     } else {
 230       _expand_heap_after_alloc_failure = false;
 231     }
 232   }
 233   return res;
 234 }
 235 
 236 HeapWord*
 237 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 238                                                            uint num_regions,
 239                                                            size_t word_size,
 240                                                            AllocationContext_t context) {
 241   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 242   assert(is_humongous(word_size), "word_size should be humongous");
 243   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 244 
 245   // Index of last region in the series.
 246   uint last = first + num_regions - 1;
 247 
 248   // We need to initialize the region(s) we just discovered. This is
 249   // a bit tricky given that it can happen concurrently with
 250   // refinement threads refining cards on these regions and
 251   // potentially wanting to refine the BOT as they are scanning
 252   // those cards (this can happen shortly after a cleanup; see CR
 253   // 6991377). So we have to set up the region(s) carefully and in
 254   // a specific order.
 255 
 256   // The word size sum of all the regions we will allocate.
 257   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 258   assert(word_size <= word_size_sum, "sanity");
 259 
 260   // This will be the "starts humongous" region.
 261   HeapRegion* first_hr = region_at(first);
 262   // The header of the new object will be placed at the bottom of
 263   // the first region.
 264   HeapWord* new_obj = first_hr->bottom();
 265   // This will be the new top of the new object.
 266   HeapWord* obj_top = new_obj + word_size;
 267 
 268   // First, we need to zero the header of the space that we will be
 269   // allocating. When we update top further down, some refinement
 270   // threads might try to scan the region. By zeroing the header we
 271   // ensure that any thread that will try to scan the region will
 272   // come across the zero klass word and bail out.
 273   //
 274   // NOTE: It would not have been correct to have used
 275   // CollectedHeap::fill_with_object() and make the space look like
 276   // an int array. The thread that is doing the allocation will
 277   // later update the object header to a potentially different array
 278   // type and, for a very short period of time, the klass and length
 279   // fields will be inconsistent. This could cause a refinement
 280   // thread to calculate the object size incorrectly.
 281   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 282 
 283   // Next, pad out the unused tail of the last region with filler
 284   // objects, for improved usage accounting.
 285   // How many words we use for filler objects.
 286   size_t word_fill_size = word_size_sum - word_size;
 287 
 288   // How many words memory we "waste" which cannot hold a filler object.
 289   size_t words_not_fillable = 0;
 290 
 291   if (word_fill_size >= min_fill_size()) {
 292     fill_with_objects(obj_top, word_fill_size);
 293   } else if (word_fill_size > 0) {
 294     // We have space to fill, but we cannot fit an object there.
 295     words_not_fillable = word_fill_size;
 296     word_fill_size = 0;
 297   }
 298 
 299   // We will set up the first region as "starts humongous". This
 300   // will also update the BOT covering all the regions to reflect
 301   // that there is a single object that starts at the bottom of the
 302   // first region.
 303   first_hr->set_starts_humongous(obj_top, word_fill_size);
 304   first_hr->set_allocation_context(context);
 305   // Then, if there are any, we will set up the "continues
 306   // humongous" regions.
 307   HeapRegion* hr = NULL;
 308   for (uint i = first + 1; i <= last; ++i) {
 309     hr = region_at(i);
 310     hr->set_continues_humongous(first_hr);
 311     hr->set_allocation_context(context);
 312   }
 313 
 314   // Up to this point no concurrent thread would have been able to
 315   // do any scanning on any region in this series. All the top
 316   // fields still point to bottom, so the intersection between
 317   // [bottom,top] and [card_start,card_end] will be empty. Before we
 318   // update the top fields, we'll do a storestore to make sure that
 319   // no thread sees the update to top before the zeroing of the
 320   // object header and the BOT initialization.
 321   OrderAccess::storestore();
 322 
 323   // Now, we will update the top fields of the "continues humongous"
 324   // regions except the last one.
 325   for (uint i = first; i < last; ++i) {
 326     hr = region_at(i);
 327     hr->set_top(hr->end());
 328   }
 329 
 330   hr = region_at(last);
 331   // If we cannot fit a filler object, we must set top to the end
 332   // of the humongous object, otherwise we cannot iterate the heap
 333   // and the BOT will not be complete.
 334   hr->set_top(hr->end() - words_not_fillable);
 335 
 336   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 337          "obj_top should be in last region");
 338 
 339   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 340 
 341   assert(words_not_fillable == 0 ||
 342          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 343          "Miscalculation in humongous allocation");
 344 
 345   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 346 
 347   for (uint i = first; i <= last; ++i) {
 348     hr = region_at(i);
 349     _humongous_set.add(hr);
 350     _hr_printer.alloc(hr);
 351   }
 352 
 353   return new_obj;
 354 }
 355 
 356 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 357   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 358   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 359 }
 360 
 361 // If could fit into free regions w/o expansion, try.
 362 // Otherwise, if can expand, do so.
 363 // Otherwise, if using ex regions might help, try with ex given back.
 364 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 365   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 366 
 367   _verifier->verify_region_sets_optional();
 368 
 369   uint first = G1_NO_HRM_INDEX;
 370   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 371 
 372   if (obj_regions == 1) {
 373     // Only one region to allocate, try to use a fast path by directly allocating
 374     // from the free lists. Do not try to expand here, we will potentially do that
 375     // later.
 376     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 377     if (hr != NULL) {
 378       first = hr->hrm_index();
 379     }
 380   } else {
 381     // We can't allocate humongous regions spanning more than one region while
 382     // cleanupComplete() is running, since some of the regions we find to be
 383     // empty might not yet be added to the free list. It is not straightforward
 384     // to know in which list they are on so that we can remove them. We only
 385     // need to do this if we need to allocate more than one region to satisfy the
 386     // current humongous allocation request. If we are only allocating one region
 387     // we use the one-region region allocation code (see above), that already
 388     // potentially waits for regions from the secondary free list.
 389     wait_while_free_regions_coming();
 390     append_secondary_free_list_if_not_empty_with_lock();
 391 
 392     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 393     // are lucky enough to find some.
 394     first = _hrm.find_contiguous_only_empty(obj_regions);
 395     if (first != G1_NO_HRM_INDEX) {
 396       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 397     }
 398   }
 399 
 400   if (first == G1_NO_HRM_INDEX) {
 401     // Policy: We could not find enough regions for the humongous object in the
 402     // free list. Look through the heap to find a mix of free and uncommitted regions.
 403     // If so, try expansion.
 404     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 405     if (first != G1_NO_HRM_INDEX) {
 406       // We found something. Make sure these regions are committed, i.e. expand
 407       // the heap. Alternatively we could do a defragmentation GC.
 408       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 409                                     word_size * HeapWordSize);
 410 
 411       _hrm.expand_at(first, obj_regions, workers());
 412       g1_policy()->record_new_heap_size(num_regions());
 413 
 414 #ifdef ASSERT
 415       for (uint i = first; i < first + obj_regions; ++i) {
 416         HeapRegion* hr = region_at(i);
 417         assert(hr->is_free(), "sanity");
 418         assert(hr->is_empty(), "sanity");
 419         assert(is_on_master_free_list(hr), "sanity");
 420       }
 421 #endif
 422       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 423     } else {
 424       // Policy: Potentially trigger a defragmentation GC.
 425     }
 426   }
 427 
 428   HeapWord* result = NULL;
 429   if (first != G1_NO_HRM_INDEX) {
 430     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 431                                                        word_size, context);
 432     assert(result != NULL, "it should always return a valid result");
 433 
 434     // A successful humongous object allocation changes the used space
 435     // information of the old generation so we need to recalculate the
 436     // sizes and update the jstat counters here.
 437     g1mm()->update_sizes();
 438   }
 439 
 440   _verifier->verify_region_sets_optional();
 441 
 442   return result;
 443 }
 444 
 445 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 446   assert_heap_not_locked_and_not_at_safepoint();
 447   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 448 
 449   return attempt_allocation(word_size);
 450 }
 451 
 452 HeapWord*
 453 G1CollectedHeap::mem_allocate(size_t word_size,
 454                               bool*  gc_overhead_limit_was_exceeded) {
 455   assert_heap_not_locked_and_not_at_safepoint();
 456 
 457   if (is_humongous(word_size)) {
 458     return attempt_allocation_humongous(word_size);
 459   }
 460   return attempt_allocation(word_size);
 461 }
 462 
 463 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 464                                                    AllocationContext_t context) {
 465   ResourceMark rm; // For retrieving the thread names in log messages.
 466 
 467   // Make sure you read the note in attempt_allocation_humongous().
 468 
 469   assert_heap_not_locked_and_not_at_safepoint();
 470   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 471          "be called for humongous allocation requests");
 472 
 473   // We should only get here after the first-level allocation attempt
 474   // (attempt_allocation()) failed to allocate.
 475 
 476   // We will loop until a) we manage to successfully perform the
 477   // allocation or b) we successfully schedule a collection which
 478   // fails to perform the allocation. b) is the only case when we'll
 479   // return NULL.
 480   HeapWord* result = NULL;
 481   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 482     bool should_try_gc;
 483     uint gc_count_before;
 484 
 485     {
 486       MutexLockerEx x(Heap_lock);
 487       result = _allocator->attempt_allocation_locked(word_size, context);
 488       if (result != NULL) {
 489         return result;
 490       }
 491 
 492       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 493       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 494       // waiting because the GCLocker is active to not wait too long.
 495       if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
 496         // No need for an ergo message here, can_expand_young_list() does this when
 497         // it returns true.
 498         result = _allocator->attempt_allocation_force(word_size, context);
 499         if (result != NULL) {
 500           return result;
 501         }
 502       }
 503       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 504       // the GCLocker initiated GC has been performed and then retry. This includes
 505       // the case when the GC Locker is not active but has not been performed.
 506       should_try_gc = !GCLocker::needs_gc();
 507       // Read the GC count while still holding the Heap_lock.
 508       gc_count_before = total_collections();
 509     }
 510 
 511     if (should_try_gc) {
 512       bool succeeded;
 513       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 514                                    GCCause::_g1_inc_collection_pause);
 515       if (result != NULL) {
 516         assert(succeeded, "only way to get back a non-NULL result");
 517         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 518                              Thread::current()->name(), p2i(result));
 519         return result;
 520       }
 521 
 522       if (succeeded) {
 523         // We successfully scheduled a collection which failed to allocate. No
 524         // point in trying to allocate further. We'll just return NULL.
 525         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 526                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 527         return NULL;
 528       }
 529       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 530                            Thread::current()->name(), word_size);
 531     } else {
 532       // Failed to schedule a collection.
 533       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 534         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 535                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 536         return NULL;
 537       }
 538       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 539       // The GCLocker is either active or the GCLocker initiated
 540       // GC has not yet been performed. Stall until it is and
 541       // then retry the allocation.
 542       GCLocker::stall_until_clear();
 543       gclocker_retry_count += 1;
 544     }
 545 
 546     // We can reach here if we were unsuccessful in scheduling a
 547     // collection (because another thread beat us to it) or if we were
 548     // stalled due to the GC locker. In either can we should retry the
 549     // allocation attempt in case another thread successfully
 550     // performed a collection and reclaimed enough space. We do the
 551     // first attempt (without holding the Heap_lock) here and the
 552     // follow-on attempt will be at the start of the next loop
 553     // iteration (after taking the Heap_lock).
 554 
 555     result = _allocator->attempt_allocation(word_size, context);
 556     if (result != NULL) {
 557       return result;
 558     }
 559 
 560     // Give a warning if we seem to be looping forever.
 561     if ((QueuedAllocationWarningCount > 0) &&
 562         (try_count % QueuedAllocationWarningCount == 0)) {
 563       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 564                              Thread::current()->name(), try_count, word_size);
 565     }
 566   }
 567 
 568   ShouldNotReachHere();
 569   return NULL;
 570 }
 571 
 572 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 573   assert_at_safepoint(true /* should_be_vm_thread */);
 574   if (_archive_allocator == NULL) {
 575     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 576   }
 577 }
 578 
 579 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 580   // Allocations in archive regions cannot be of a size that would be considered
 581   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 582   // may be different at archive-restore time.
 583   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 584 }
 585 
 586 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 587   assert_at_safepoint(true /* should_be_vm_thread */);
 588   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 589   if (is_archive_alloc_too_large(word_size)) {
 590     return NULL;
 591   }
 592   return _archive_allocator->archive_mem_allocate(word_size);
 593 }
 594 
 595 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 596                                               size_t end_alignment_in_bytes) {
 597   assert_at_safepoint(true /* should_be_vm_thread */);
 598   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 599 
 600   // Call complete_archive to do the real work, filling in the MemRegion
 601   // array with the archive regions.
 602   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 603   delete _archive_allocator;
 604   _archive_allocator = NULL;
 605 }
 606 
 607 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 608   assert(ranges != NULL, "MemRegion array NULL");
 609   assert(count != 0, "No MemRegions provided");
 610   MemRegion reserved = _hrm.reserved();
 611   for (size_t i = 0; i < count; i++) {
 612     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 613       return false;
 614     }
 615   }
 616   return true;
 617 }
 618 
 619 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 620                                             size_t count,
 621                                             bool open) {
 622   assert(!is_init_completed(), "Expect to be called at JVM init time");
 623   assert(ranges != NULL, "MemRegion array NULL");
 624   assert(count != 0, "No MemRegions provided");
 625   MutexLockerEx x(Heap_lock);
 626 
 627   MemRegion reserved = _hrm.reserved();
 628   HeapWord* prev_last_addr = NULL;
 629   HeapRegion* prev_last_region = NULL;
 630 
 631   // Temporarily disable pretouching of heap pages. This interface is used
 632   // when mmap'ing archived heap data in, so pre-touching is wasted.
 633   FlagSetting fs(AlwaysPreTouch, false);
 634 
 635   // Enable archive object checking used by G1MarkSweep. We have to let it know
 636   // about each archive range, so that objects in those ranges aren't marked.
 637   G1ArchiveAllocator::enable_archive_object_check();
 638 
 639   // For each specified MemRegion range, allocate the corresponding G1
 640   // regions and mark them as archive regions. We expect the ranges
 641   // in ascending starting address order, without overlap.
 642   for (size_t i = 0; i < count; i++) {
 643     MemRegion curr_range = ranges[i];
 644     HeapWord* start_address = curr_range.start();
 645     size_t word_size = curr_range.word_size();
 646     HeapWord* last_address = curr_range.last();
 647     size_t commits = 0;
 648 
 649     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 650               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 651               p2i(start_address), p2i(last_address));
 652     guarantee(start_address > prev_last_addr,
 653               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 654               p2i(start_address), p2i(prev_last_addr));
 655     prev_last_addr = last_address;
 656 
 657     // Check for ranges that start in the same G1 region in which the previous
 658     // range ended, and adjust the start address so we don't try to allocate
 659     // the same region again. If the current range is entirely within that
 660     // region, skip it, just adjusting the recorded top.
 661     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 662     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 663       start_address = start_region->end();
 664       if (start_address > last_address) {
 665         increase_used(word_size * HeapWordSize);
 666         start_region->set_top(last_address + 1);
 667         continue;
 668       }
 669       start_region->set_top(start_address);
 670       curr_range = MemRegion(start_address, last_address + 1);
 671       start_region = _hrm.addr_to_region(start_address);
 672     }
 673 
 674     // Perform the actual region allocation, exiting if it fails.
 675     // Then note how much new space we have allocated.
 676     if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
 677       return false;
 678     }
 679     increase_used(word_size * HeapWordSize);
 680     if (commits != 0) {
 681       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 682                                 HeapRegion::GrainWords * HeapWordSize * commits);
 683 
 684     }
 685 
 686     // Mark each G1 region touched by the range as archive, add it to
 687     // the old set, and set the allocation context and top.
 688     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 689     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 690     prev_last_region = last_region;
 691 
 692     while (curr_region != NULL) {
 693       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 694              "Region already in use (index %u)", curr_region->hrm_index());
 695       curr_region->set_allocation_context(AllocationContext::system());
 696       if (open) {
 697         curr_region->set_open_archive();
 698       } else {
 699         curr_region->set_closed_archive();
 700       }
 701       _hr_printer.alloc(curr_region);
 702       _old_set.add(curr_region);
 703       HeapWord* top;
 704       HeapRegion* next_region;
 705       if (curr_region != last_region) {
 706         top = curr_region->end();
 707         next_region = _hrm.next_region_in_heap(curr_region);
 708       } else {
 709         top = last_address + 1;
 710         next_region = NULL;
 711       }
 712       curr_region->set_top(top);
 713       curr_region->set_first_dead(top);
 714       curr_region->set_end_of_live(top);
 715       curr_region = next_region;
 716     }
 717 
 718     // Notify mark-sweep of the archive
 719     G1ArchiveAllocator::set_range_archive(curr_range, open);
 720   }
 721   return true;
 722 }
 723 
 724 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 725   assert(!is_init_completed(), "Expect to be called at JVM init time");
 726   assert(ranges != NULL, "MemRegion array NULL");
 727   assert(count != 0, "No MemRegions provided");
 728   MemRegion reserved = _hrm.reserved();
 729   HeapWord *prev_last_addr = NULL;
 730   HeapRegion* prev_last_region = NULL;
 731 
 732   // For each MemRegion, create filler objects, if needed, in the G1 regions
 733   // that contain the address range. The address range actually within the
 734   // MemRegion will not be modified. That is assumed to have been initialized
 735   // elsewhere, probably via an mmap of archived heap data.
 736   MutexLockerEx x(Heap_lock);
 737   for (size_t i = 0; i < count; i++) {
 738     HeapWord* start_address = ranges[i].start();
 739     HeapWord* last_address = ranges[i].last();
 740 
 741     assert(reserved.contains(start_address) && reserved.contains(last_address),
 742            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 743            p2i(start_address), p2i(last_address));
 744     assert(start_address > prev_last_addr,
 745            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 746            p2i(start_address), p2i(prev_last_addr));
 747 
 748     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 749     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 750     HeapWord* bottom_address = start_region->bottom();
 751 
 752     // Check for a range beginning in the same region in which the
 753     // previous one ended.
 754     if (start_region == prev_last_region) {
 755       bottom_address = prev_last_addr + 1;
 756     }
 757 
 758     // Verify that the regions were all marked as archive regions by
 759     // alloc_archive_regions.
 760     HeapRegion* curr_region = start_region;
 761     while (curr_region != NULL) {
 762       guarantee(curr_region->is_archive(),
 763                 "Expected archive region at index %u", curr_region->hrm_index());
 764       if (curr_region != last_region) {
 765         curr_region = _hrm.next_region_in_heap(curr_region);
 766       } else {
 767         curr_region = NULL;
 768       }
 769     }
 770 
 771     prev_last_addr = last_address;
 772     prev_last_region = last_region;
 773 
 774     // Fill the memory below the allocated range with dummy object(s),
 775     // if the region bottom does not match the range start, or if the previous
 776     // range ended within the same G1 region, and there is a gap.
 777     if (start_address != bottom_address) {
 778       size_t fill_size = pointer_delta(start_address, bottom_address);
 779       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 780       increase_used(fill_size * HeapWordSize);
 781     }
 782   }
 783 }
 784 
 785 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) {
 786   assert_heap_not_locked_and_not_at_safepoint();
 787   assert(!is_humongous(word_size), "attempt_allocation() should not "
 788          "be called for humongous allocation requests");
 789 
 790   AllocationContext_t context = AllocationContext::current();
 791   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 792 
 793   if (result == NULL) {
 794     result = attempt_allocation_slow(word_size, context);
 795   }
 796   assert_heap_not_locked();
 797   if (result != NULL) {
 798     dirty_young_block(result, word_size);
 799   }
 800   return result;
 801 }
 802 
 803 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 804   assert(!is_init_completed(), "Expect to be called at JVM init time");
 805   assert(ranges != NULL, "MemRegion array NULL");
 806   assert(count != 0, "No MemRegions provided");
 807   MemRegion reserved = _hrm.reserved();
 808   HeapWord* prev_last_addr = NULL;
 809   HeapRegion* prev_last_region = NULL;
 810   size_t size_used = 0;
 811   size_t uncommitted_regions = 0;
 812 
 813   // For each Memregion, free the G1 regions that constitute it, and
 814   // notify mark-sweep that the range is no longer to be considered 'archive.'
 815   MutexLockerEx x(Heap_lock);
 816   for (size_t i = 0; i < count; i++) {
 817     HeapWord* start_address = ranges[i].start();
 818     HeapWord* last_address = ranges[i].last();
 819 
 820     assert(reserved.contains(start_address) && reserved.contains(last_address),
 821            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 822            p2i(start_address), p2i(last_address));
 823     assert(start_address > prev_last_addr,
 824            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 825            p2i(start_address), p2i(prev_last_addr));
 826     size_used += ranges[i].byte_size();
 827     prev_last_addr = last_address;
 828 
 829     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 830     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 831 
 832     // Check for ranges that start in the same G1 region in which the previous
 833     // range ended, and adjust the start address so we don't try to free
 834     // the same region again. If the current range is entirely within that
 835     // region, skip it.
 836     if (start_region == prev_last_region) {
 837       start_address = start_region->end();
 838       if (start_address > last_address) {
 839         continue;
 840       }
 841       start_region = _hrm.addr_to_region(start_address);
 842     }
 843     prev_last_region = last_region;
 844 
 845     // After verifying that each region was marked as an archive region by
 846     // alloc_archive_regions, set it free and empty and uncommit it.
 847     HeapRegion* curr_region = start_region;
 848     while (curr_region != NULL) {
 849       guarantee(curr_region->is_archive(),
 850                 "Expected archive region at index %u", curr_region->hrm_index());
 851       uint curr_index = curr_region->hrm_index();
 852       _old_set.remove(curr_region);
 853       curr_region->set_free();
 854       curr_region->set_top(curr_region->bottom());
 855       if (curr_region != last_region) {
 856         curr_region = _hrm.next_region_in_heap(curr_region);
 857       } else {
 858         curr_region = NULL;
 859       }
 860       _hrm.shrink_at(curr_index, 1);
 861       uncommitted_regions++;
 862     }
 863 
 864     // Notify mark-sweep that this is no longer an archive range.
 865     G1ArchiveAllocator::set_range_archive(ranges[i], false);
 866   }
 867 
 868   if (uncommitted_regions != 0) {
 869     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 870                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 871   }
 872   decrease_used(size_used);
 873 }
 874 
 875 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 876   ResourceMark rm; // For retrieving the thread names in log messages.
 877 
 878   // The structure of this method has a lot of similarities to
 879   // attempt_allocation_slow(). The reason these two were not merged
 880   // into a single one is that such a method would require several "if
 881   // allocation is not humongous do this, otherwise do that"
 882   // conditional paths which would obscure its flow. In fact, an early
 883   // version of this code did use a unified method which was harder to
 884   // follow and, as a result, it had subtle bugs that were hard to
 885   // track down. So keeping these two methods separate allows each to
 886   // be more readable. It will be good to keep these two in sync as
 887   // much as possible.
 888 
 889   assert_heap_not_locked_and_not_at_safepoint();
 890   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 891          "should only be called for humongous allocations");
 892 
 893   // Humongous objects can exhaust the heap quickly, so we should check if we
 894   // need to start a marking cycle at each humongous object allocation. We do
 895   // the check before we do the actual allocation. The reason for doing it
 896   // before the allocation is that we avoid having to keep track of the newly
 897   // allocated memory while we do a GC.
 898   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 899                                            word_size)) {
 900     collect(GCCause::_g1_humongous_allocation);
 901   }
 902 
 903   // We will loop until a) we manage to successfully perform the
 904   // allocation or b) we successfully schedule a collection which
 905   // fails to perform the allocation. b) is the only case when we'll
 906   // return NULL.
 907   HeapWord* result = NULL;
 908   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 909     bool should_try_gc;
 910     uint gc_count_before;
 911 
 912 
 913     {
 914       MutexLockerEx x(Heap_lock);
 915 
 916       // Given that humongous objects are not allocated in young
 917       // regions, we'll first try to do the allocation without doing a
 918       // collection hoping that there's enough space in the heap.
 919       result = humongous_obj_allocate(word_size, AllocationContext::current());
 920       if (result != NULL) {
 921         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 922         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 923         return result;
 924       }
 925 
 926       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 927       // the GCLocker initiated GC has been performed and then retry. This includes
 928       // the case when the GC Locker is not active but has not been performed.
 929       should_try_gc = !GCLocker::needs_gc();
 930       // Read the GC count while still holding the Heap_lock.
 931       gc_count_before = total_collections();
 932     }
 933 
 934     if (should_try_gc) {
 935       bool succeeded;
 936       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 937                                    GCCause::_g1_humongous_allocation);
 938       if (result != NULL) {
 939         assert(succeeded, "only way to get back a non-NULL result");
 940         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 941                              Thread::current()->name(), p2i(result));
 942         return result;
 943       }
 944 
 945       if (succeeded) {
 946         // We successfully scheduled a collection which failed to allocate. No
 947         // point in trying to allocate further. We'll just return NULL.
 948         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 949                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 950         return NULL;
 951       }
 952       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 953                            Thread::current()->name(), word_size);
 954     } else {
 955       // Failed to schedule a collection.
 956       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 957         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 958                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 959         return NULL;
 960       }
 961       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 962       // The GCLocker is either active or the GCLocker initiated
 963       // GC has not yet been performed. Stall until it is and
 964       // then retry the allocation.
 965       GCLocker::stall_until_clear();
 966       gclocker_retry_count += 1;
 967     }
 968 
 969 
 970     // We can reach here if we were unsuccessful in scheduling a
 971     // collection (because another thread beat us to it) or if we were
 972     // stalled due to the GC locker. In either can we should retry the
 973     // allocation attempt in case another thread successfully
 974     // performed a collection and reclaimed enough space.
 975     // Humongous object allocation always needs a lock, so we wait for the retry
 976     // in the next iteration of the loop, unlike for the regular iteration case.
 977     // Give a warning if we seem to be looping forever.
 978 
 979     if ((QueuedAllocationWarningCount > 0) &&
 980         (try_count % QueuedAllocationWarningCount == 0)) {
 981       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 982                              Thread::current()->name(), try_count, word_size);
 983     }
 984   }
 985 
 986   ShouldNotReachHere();
 987   return NULL;
 988 }
 989 
 990 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 991                                                            AllocationContext_t context,
 992                                                            bool expect_null_mutator_alloc_region) {
 993   assert_at_safepoint(true /* should_be_vm_thread */);
 994   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
 995          "the current alloc region was unexpectedly found to be non-NULL");
 996 
 997   if (!is_humongous(word_size)) {
 998     return _allocator->attempt_allocation_locked(word_size, context);
 999   } else {
1000     HeapWord* result = humongous_obj_allocate(word_size, context);
1001     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1002       collector_state()->set_initiate_conc_mark_if_possible(true);
1003     }
1004     return result;
1005   }
1006 
1007   ShouldNotReachHere();
1008 }
1009 
1010 class PostCompactionPrinterClosure: public HeapRegionClosure {
1011 private:
1012   G1HRPrinter* _hr_printer;
1013 public:
1014   bool do_heap_region(HeapRegion* hr) {
1015     assert(!hr->is_young(), "not expecting to find young regions");
1016     _hr_printer->post_compaction(hr);
1017     return false;
1018   }
1019 
1020   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1021     : _hr_printer(hr_printer) { }
1022 };
1023 
1024 void G1CollectedHeap::print_hrm_post_compaction() {
1025   if (_hr_printer.is_active()) {
1026     PostCompactionPrinterClosure cl(hr_printer());
1027     heap_region_iterate(&cl);
1028   }
1029 }
1030 
1031 void G1CollectedHeap::abort_concurrent_cycle() {
1032   // Note: When we have a more flexible GC logging framework that
1033   // allows us to add optional attributes to a GC log record we
1034   // could consider timing and reporting how long we wait in the
1035   // following two methods.
1036   wait_while_free_regions_coming();
1037   // If we start the compaction before the CM threads finish
1038   // scanning the root regions we might trip them over as we'll
1039   // be moving objects / updating references. So let's wait until
1040   // they are done. By telling them to abort, they should complete
1041   // early.
1042   _cm->root_regions()->abort();
1043   _cm->root_regions()->wait_until_scan_finished();
1044   append_secondary_free_list_if_not_empty_with_lock();
1045 
1046   // Disable discovery and empty the discovered lists
1047   // for the CM ref processor.
1048   ref_processor_cm()->disable_discovery();
1049   ref_processor_cm()->abandon_partial_discovery();
1050   ref_processor_cm()->verify_no_references_recorded();
1051 
1052   // Abandon current iterations of concurrent marking and concurrent
1053   // refinement, if any are in progress.
1054   concurrent_mark()->abort();
1055 }
1056 
1057 void G1CollectedHeap::prepare_heap_for_full_collection() {
1058   // Make sure we'll choose a new allocation region afterwards.
1059   _allocator->release_mutator_alloc_region();
1060   _allocator->abandon_gc_alloc_regions();
1061   g1_rem_set()->cleanupHRRS();
1062 
1063   // We may have added regions to the current incremental collection
1064   // set between the last GC or pause and now. We need to clear the
1065   // incremental collection set and then start rebuilding it afresh
1066   // after this full GC.
1067   abandon_collection_set(collection_set());
1068 
1069   tear_down_region_sets(false /* free_list_only */);
1070   collector_state()->set_gcs_are_young(true);
1071 }
1072 
1073 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1074   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1075   assert(used() == recalculate_used(), "Should be equal");
1076   _verifier->verify_region_sets_optional();
1077   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1078   _verifier->check_bitmaps("Full GC Start");
1079 }
1080 
1081 void G1CollectedHeap::prepare_heap_for_mutators() {
1082   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1083   ClassLoaderDataGraph::purge();
1084   MetaspaceAux::verify_metrics();
1085 
1086   // Prepare heap for normal collections.
1087   assert(num_free_regions() == 0, "we should not have added any free regions");
1088   rebuild_region_sets(false /* free_list_only */);
1089   abort_refinement();
1090   resize_if_necessary_after_full_collection();
1091 
1092   // Rebuild the strong code root lists for each region
1093   rebuild_strong_code_roots();
1094 
1095   // Start a new incremental collection set for the next pause
1096   start_new_collection_set();
1097 
1098   _allocator->init_mutator_alloc_region();
1099 
1100   // Post collection state updates.
1101   MetaspaceGC::compute_new_size();
1102 }
1103 
1104 void G1CollectedHeap::abort_refinement() {
1105   if (_hot_card_cache->use_cache()) {
1106     _hot_card_cache->reset_hot_cache();
1107   }
1108 
1109   // Discard all remembered set updates.
1110   JavaThread::dirty_card_queue_set().abandon_logs();
1111   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1112 }
1113 
1114 void G1CollectedHeap::verify_after_full_collection() {
1115   check_gc_time_stamps();
1116   _hrm.verify_optional();
1117   _verifier->verify_region_sets_optional();
1118   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1119   // Clear the previous marking bitmap, if needed for bitmap verification.
1120   // Note we cannot do this when we clear the next marking bitmap in
1121   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1122   // objects marked during a full GC against the previous bitmap.
1123   // But we need to clear it before calling check_bitmaps below since
1124   // the full GC has compacted objects and updated TAMS but not updated
1125   // the prev bitmap.
1126   if (G1VerifyBitmaps) {
1127     GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1128     _cm->clear_prev_bitmap(workers());
1129   }
1130   _verifier->check_bitmaps("Full GC End");
1131 
1132   // At this point there should be no regions in the
1133   // entire heap tagged as young.
1134   assert(check_young_list_empty(), "young list should be empty at this point");
1135 
1136   // Note: since we've just done a full GC, concurrent
1137   // marking is no longer active. Therefore we need not
1138   // re-enable reference discovery for the CM ref processor.
1139   // That will be done at the start of the next marking cycle.
1140   // We also know that the STW processor should no longer
1141   // discover any new references.
1142   assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1143   assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1144   ref_processor_stw()->verify_no_references_recorded();
1145   ref_processor_cm()->verify_no_references_recorded();
1146 }
1147 
1148 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1149   // Post collection logging.
1150   // We should do this after we potentially resize the heap so
1151   // that all the COMMIT / UNCOMMIT events are generated before
1152   // the compaction events.
1153   print_hrm_post_compaction();
1154   heap_transition->print();
1155   print_heap_after_gc();
1156   print_heap_regions();
1157 #ifdef TRACESPINNING
1158   ParallelTaskTerminator::print_termination_counts();
1159 #endif
1160 }
1161 
1162 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1163                                          bool clear_all_soft_refs) {
1164   assert_at_safepoint(true /* should_be_vm_thread */);
1165 
1166   if (GCLocker::check_active_before_gc()) {
1167     // Full GC was not completed.
1168     return false;
1169   }
1170 
1171   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1172       soft_ref_policy()->should_clear_all_soft_refs();
1173 
1174   G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1175   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1176 
1177   collector.prepare_collection();
1178   collector.collect();
1179   collector.complete_collection();
1180 
1181   // Full collection was successfully completed.
1182   return true;
1183 }
1184 
1185 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1186   // Currently, there is no facility in the do_full_collection(bool) API to notify
1187   // the caller that the collection did not succeed (e.g., because it was locked
1188   // out by the GC locker). So, right now, we'll ignore the return value.
1189   bool dummy = do_full_collection(true,                /* explicit_gc */
1190                                   clear_all_soft_refs);
1191 }
1192 
1193 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1194   // Capacity, free and used after the GC counted as full regions to
1195   // include the waste in the following calculations.
1196   const size_t capacity_after_gc = capacity();
1197   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1198 
1199   // This is enforced in arguments.cpp.
1200   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1201          "otherwise the code below doesn't make sense");
1202 
1203   // We don't have floating point command-line arguments
1204   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1205   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1206   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1207   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1208 
1209   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1210   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1211 
1212   // We have to be careful here as these two calculations can overflow
1213   // 32-bit size_t's.
1214   double used_after_gc_d = (double) used_after_gc;
1215   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1216   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1217 
1218   // Let's make sure that they are both under the max heap size, which
1219   // by default will make them fit into a size_t.
1220   double desired_capacity_upper_bound = (double) max_heap_size;
1221   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1222                                     desired_capacity_upper_bound);
1223   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1224                                     desired_capacity_upper_bound);
1225 
1226   // We can now safely turn them into size_t's.
1227   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1228   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1229 
1230   // This assert only makes sense here, before we adjust them
1231   // with respect to the min and max heap size.
1232   assert(minimum_desired_capacity <= maximum_desired_capacity,
1233          "minimum_desired_capacity = " SIZE_FORMAT ", "
1234          "maximum_desired_capacity = " SIZE_FORMAT,
1235          minimum_desired_capacity, maximum_desired_capacity);
1236 
1237   // Should not be greater than the heap max size. No need to adjust
1238   // it with respect to the heap min size as it's a lower bound (i.e.,
1239   // we'll try to make the capacity larger than it, not smaller).
1240   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1241   // Should not be less than the heap min size. No need to adjust it
1242   // with respect to the heap max size as it's an upper bound (i.e.,
1243   // we'll try to make the capacity smaller than it, not greater).
1244   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1245 
1246   if (capacity_after_gc < minimum_desired_capacity) {
1247     // Don't expand unless it's significant
1248     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1249 
1250     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1251                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1252                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1253                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1254 
1255     expand(expand_bytes, _workers);
1256 
1257     // No expansion, now see if we want to shrink
1258   } else if (capacity_after_gc > maximum_desired_capacity) {
1259     // Capacity too large, compute shrinking size
1260     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1261 
1262     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1263                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1264                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1265                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1266 
1267     shrink(shrink_bytes);
1268   }
1269 }
1270 
1271 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1272                                                             AllocationContext_t context,
1273                                                             bool do_gc,
1274                                                             bool clear_all_soft_refs,
1275                                                             bool expect_null_mutator_alloc_region,
1276                                                             bool* gc_succeeded) {
1277   *gc_succeeded = true;
1278   // Let's attempt the allocation first.
1279   HeapWord* result =
1280     attempt_allocation_at_safepoint(word_size,
1281                                     context,
1282                                     expect_null_mutator_alloc_region);
1283   if (result != NULL) {
1284     return result;
1285   }
1286 
1287   // In a G1 heap, we're supposed to keep allocation from failing by
1288   // incremental pauses.  Therefore, at least for now, we'll favor
1289   // expansion over collection.  (This might change in the future if we can
1290   // do something smarter than full collection to satisfy a failed alloc.)
1291   result = expand_and_allocate(word_size, context);
1292   if (result != NULL) {
1293     return result;
1294   }
1295 
1296   if (do_gc) {
1297     // Expansion didn't work, we'll try to do a Full GC.
1298     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1299                                        clear_all_soft_refs);
1300   }
1301 
1302   return NULL;
1303 }
1304 
1305 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1306                                                      AllocationContext_t context,
1307                                                      bool* succeeded) {
1308   assert_at_safepoint(true /* should_be_vm_thread */);
1309 
1310   // Attempts to allocate followed by Full GC.
1311   HeapWord* result =
1312     satisfy_failed_allocation_helper(word_size,
1313                                      context,
1314                                      true,  /* do_gc */
1315                                      false, /* clear_all_soft_refs */
1316                                      false, /* expect_null_mutator_alloc_region */
1317                                      succeeded);
1318 
1319   if (result != NULL || !*succeeded) {
1320     return result;
1321   }
1322 
1323   // Attempts to allocate followed by Full GC that will collect all soft references.
1324   result = satisfy_failed_allocation_helper(word_size,
1325                                             context,
1326                                             true, /* do_gc */
1327                                             true, /* clear_all_soft_refs */
1328                                             true, /* expect_null_mutator_alloc_region */
1329                                             succeeded);
1330 
1331   if (result != NULL || !*succeeded) {
1332     return result;
1333   }
1334 
1335   // Attempts to allocate, no GC
1336   result = satisfy_failed_allocation_helper(word_size,
1337                                             context,
1338                                             false, /* do_gc */
1339                                             false, /* clear_all_soft_refs */
1340                                             true,  /* expect_null_mutator_alloc_region */
1341                                             succeeded);
1342 
1343   if (result != NULL) {
1344     return result;
1345   }
1346 
1347   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1348          "Flag should have been handled and cleared prior to this point");
1349 
1350   // What else?  We might try synchronous finalization later.  If the total
1351   // space available is large enough for the allocation, then a more
1352   // complete compaction phase than we've tried so far might be
1353   // appropriate.
1354   return NULL;
1355 }
1356 
1357 // Attempting to expand the heap sufficiently
1358 // to support an allocation of the given "word_size".  If
1359 // successful, perform the allocation and return the address of the
1360 // allocated block, or else "NULL".
1361 
1362 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1363   assert_at_safepoint(true /* should_be_vm_thread */);
1364 
1365   _verifier->verify_region_sets_optional();
1366 
1367   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1368   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1369                             word_size * HeapWordSize);
1370 
1371 
1372   if (expand(expand_bytes, _workers)) {
1373     _hrm.verify_optional();
1374     _verifier->verify_region_sets_optional();
1375     return attempt_allocation_at_safepoint(word_size,
1376                                            context,
1377                                            false /* expect_null_mutator_alloc_region */);
1378   }
1379   return NULL;
1380 }
1381 
1382 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1383   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1384   aligned_expand_bytes = align_up(aligned_expand_bytes,
1385                                        HeapRegion::GrainBytes);
1386 
1387   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1388                             expand_bytes, aligned_expand_bytes);
1389 
1390   if (is_maximal_no_gc()) {
1391     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1392     return false;
1393   }
1394 
1395   double expand_heap_start_time_sec = os::elapsedTime();
1396   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1397   assert(regions_to_expand > 0, "Must expand by at least one region");
1398 
1399   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1400   if (expand_time_ms != NULL) {
1401     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1402   }
1403 
1404   if (expanded_by > 0) {
1405     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1406     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1407     g1_policy()->record_new_heap_size(num_regions());
1408   } else {
1409     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1410 
1411     // The expansion of the virtual storage space was unsuccessful.
1412     // Let's see if it was because we ran out of swap.
1413     if (G1ExitOnExpansionFailure &&
1414         _hrm.available() >= regions_to_expand) {
1415       // We had head room...
1416       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1417     }
1418   }
1419   return regions_to_expand > 0;
1420 }
1421 
1422 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1423   size_t aligned_shrink_bytes =
1424     ReservedSpace::page_align_size_down(shrink_bytes);
1425   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1426                                          HeapRegion::GrainBytes);
1427   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1428 
1429   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1430   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1431 
1432 
1433   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",
1434                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1435   if (num_regions_removed > 0) {
1436     g1_policy()->record_new_heap_size(num_regions());
1437   } else {
1438     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1439   }
1440 }
1441 
1442 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1443   _verifier->verify_region_sets_optional();
1444 
1445   // We should only reach here at the end of a Full GC which means we
1446   // should not not be holding to any GC alloc regions. The method
1447   // below will make sure of that and do any remaining clean up.
1448   _allocator->abandon_gc_alloc_regions();
1449 
1450   // Instead of tearing down / rebuilding the free lists here, we
1451   // could instead use the remove_all_pending() method on free_list to
1452   // remove only the ones that we need to remove.
1453   tear_down_region_sets(true /* free_list_only */);
1454   shrink_helper(shrink_bytes);
1455   rebuild_region_sets(true /* free_list_only */);
1456 
1457   _hrm.verify_optional();
1458   _verifier->verify_region_sets_optional();
1459 }
1460 
1461 // Public methods.
1462 
1463 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1464   CollectedHeap(),
1465   _young_gen_sampling_thread(NULL),
1466   _collector_policy(collector_policy),
1467   _soft_ref_policy(),
1468   _card_table(NULL),
1469   _memory_manager("G1 Young Generation", "end of minor GC"),
1470   _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1471   _eden_pool(NULL),
1472   _survivor_pool(NULL),
1473   _old_pool(NULL),
1474   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1475   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1476   _g1_policy(create_g1_policy(_gc_timer_stw)),
1477   _collection_set(this, _g1_policy),
1478   _dirty_card_queue_set(false),
1479   _is_alive_closure_cm(this),
1480   _is_alive_closure_stw(this),
1481   _ref_processor_cm(NULL),
1482   _ref_processor_stw(NULL),
1483   _bot(NULL),
1484   _hot_card_cache(NULL),
1485   _g1_rem_set(NULL),
1486   _cr(NULL),
1487   _g1mm(NULL),
1488   _preserved_marks_set(true /* in_c_heap */),
1489   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1490   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1491   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1492   _humongous_reclaim_candidates(),
1493   _has_humongous_reclaim_candidates(false),
1494   _archive_allocator(NULL),
1495   _free_regions_coming(false),
1496   _gc_time_stamp(0),
1497   _summary_bytes_used(0),
1498   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1499   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1500   _expand_heap_after_alloc_failure(true),
1501   _old_marking_cycles_started(0),
1502   _old_marking_cycles_completed(0),
1503   _in_cset_fast_test() {
1504 
1505   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1506                           /* are_GC_task_threads */true,
1507                           /* are_ConcurrentGC_threads */false);
1508   _workers->initialize_workers();
1509   _verifier = new G1HeapVerifier(this);
1510 
1511   _allocator = G1Allocator::create_allocator(this);
1512 
1513   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1514 
1515   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1516 
1517   // Override the default _filler_array_max_size so that no humongous filler
1518   // objects are created.
1519   _filler_array_max_size = _humongous_object_threshold_in_words;
1520 
1521   uint n_queues = ParallelGCThreads;
1522   _task_queues = new RefToScanQueueSet(n_queues);
1523 
1524   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1525 
1526   for (uint i = 0; i < n_queues; i++) {
1527     RefToScanQueue* q = new RefToScanQueue();
1528     q->initialize();
1529     _task_queues->register_queue(i, q);
1530     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1531   }
1532 
1533   // Initialize the G1EvacuationFailureALot counters and flags.
1534   NOT_PRODUCT(reset_evacuation_should_fail();)
1535 
1536   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1537 }
1538 
1539 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1540                                                                  size_t size,
1541                                                                  size_t translation_factor) {
1542   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1543   // Allocate a new reserved space, preferring to use large pages.
1544   ReservedSpace rs(size, preferred_page_size);
1545   G1RegionToSpaceMapper* result  =
1546     G1RegionToSpaceMapper::create_mapper(rs,
1547                                          size,
1548                                          rs.alignment(),
1549                                          HeapRegion::GrainBytes,
1550                                          translation_factor,
1551                                          mtGC);
1552 
1553   os::trace_page_sizes_for_requested_size(description,
1554                                           size,
1555                                           preferred_page_size,
1556                                           rs.alignment(),
1557                                           rs.base(),
1558                                           rs.size());
1559 
1560   return result;
1561 }
1562 
1563 jint G1CollectedHeap::initialize_concurrent_refinement() {
1564   jint ecode = JNI_OK;
1565   _cr = G1ConcurrentRefine::create(&ecode);
1566   return ecode;
1567 }
1568 
1569 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1570   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1571   if (_young_gen_sampling_thread->osthread() == NULL) {
1572     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1573     return JNI_ENOMEM;
1574   }
1575   return JNI_OK;
1576 }
1577 
1578 jint G1CollectedHeap::initialize() {
1579   os::enable_vtime();
1580 
1581   // Necessary to satisfy locking discipline assertions.
1582 
1583   MutexLocker x(Heap_lock);
1584 
1585   // While there are no constraints in the GC code that HeapWordSize
1586   // be any particular value, there are multiple other areas in the
1587   // system which believe this to be true (e.g. oop->object_size in some
1588   // cases incorrectly returns the size in wordSize units rather than
1589   // HeapWordSize).
1590   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1591 
1592   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1593   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1594   size_t heap_alignment = collector_policy()->heap_alignment();
1595 
1596   // Ensure that the sizes are properly aligned.
1597   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1598   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1599   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1600 
1601   // Reserve the maximum.
1602 
1603   // When compressed oops are enabled, the preferred heap base
1604   // is calculated by subtracting the requested size from the
1605   // 32Gb boundary and using the result as the base address for
1606   // heap reservation. If the requested size is not aligned to
1607   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1608   // into the ReservedHeapSpace constructor) then the actual
1609   // base of the reserved heap may end up differing from the
1610   // address that was requested (i.e. the preferred heap base).
1611   // If this happens then we could end up using a non-optimal
1612   // compressed oops mode.
1613 
1614   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1615                                                  heap_alignment);
1616 
1617   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1618 
1619   // Create the barrier set for the entire reserved region.
1620   G1CardTable* ct = new G1CardTable(reserved_region());
1621   ct->initialize();
1622   G1BarrierSet* bs = new G1BarrierSet(ct);
1623   bs->initialize();
1624   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1625   set_barrier_set(bs);
1626   _card_table = ct;
1627 
1628   // Create the hot card cache.
1629   _hot_card_cache = new G1HotCardCache(this);
1630 
1631   // Carve out the G1 part of the heap.
1632   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1633   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1634   G1RegionToSpaceMapper* heap_storage =
1635     G1RegionToSpaceMapper::create_mapper(g1_rs,
1636                                          g1_rs.size(),
1637                                          page_size,
1638                                          HeapRegion::GrainBytes,
1639                                          1,
1640                                          mtJavaHeap);
1641   os::trace_page_sizes("Heap",
1642                        collector_policy()->min_heap_byte_size(),
1643                        max_byte_size,
1644                        page_size,
1645                        heap_rs.base(),
1646                        heap_rs.size());
1647   heap_storage->set_mapping_changed_listener(&_listener);
1648 
1649   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1650   G1RegionToSpaceMapper* bot_storage =
1651     create_aux_memory_mapper("Block Offset Table",
1652                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1653                              G1BlockOffsetTable::heap_map_factor());
1654 
1655   G1RegionToSpaceMapper* cardtable_storage =
1656     create_aux_memory_mapper("Card Table",
1657                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1658                              G1CardTable::heap_map_factor());
1659 
1660   G1RegionToSpaceMapper* card_counts_storage =
1661     create_aux_memory_mapper("Card Counts Table",
1662                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1663                              G1CardCounts::heap_map_factor());
1664 
1665   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1666   G1RegionToSpaceMapper* prev_bitmap_storage =
1667     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1668   G1RegionToSpaceMapper* next_bitmap_storage =
1669     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1670 
1671   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1672   _card_table->initialize(cardtable_storage);
1673   // Do later initialization work for concurrent refinement.
1674   _hot_card_cache->initialize(card_counts_storage);
1675 
1676   // 6843694 - ensure that the maximum region index can fit
1677   // in the remembered set structures.
1678   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1679   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1680 
1681   // Also create a G1 rem set.
1682   _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1683   _g1_rem_set->initialize(max_capacity(), max_regions());
1684 
1685   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1686   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1687   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1688             "too many cards per region");
1689 
1690   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1691 
1692   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1693 
1694   {
1695     HeapWord* start = _hrm.reserved().start();
1696     HeapWord* end = _hrm.reserved().end();
1697     size_t granularity = HeapRegion::GrainBytes;
1698 
1699     _in_cset_fast_test.initialize(start, end, granularity);
1700     _humongous_reclaim_candidates.initialize(start, end, granularity);
1701   }
1702 
1703   // Create the G1ConcurrentMark data structure and thread.
1704   // (Must do this late, so that "max_regions" is defined.)
1705   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1706   if (_cm == NULL || !_cm->completed_initialization()) {
1707     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1708     return JNI_ENOMEM;
1709   }
1710   _cmThread = _cm->cm_thread();
1711 
1712   // Now expand into the initial heap size.
1713   if (!expand(init_byte_size, _workers)) {
1714     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1715     return JNI_ENOMEM;
1716   }
1717 
1718   // Perform any initialization actions delegated to the policy.
1719   g1_policy()->init(this, &_collection_set);
1720 
1721   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1722                                                SATB_Q_FL_lock,
1723                                                G1SATBProcessCompletedThreshold,
1724                                                Shared_SATB_Q_lock);
1725 
1726   jint ecode = initialize_concurrent_refinement();
1727   if (ecode != JNI_OK) {
1728     return ecode;
1729   }
1730 
1731   ecode = initialize_young_gen_sampling_thread();
1732   if (ecode != JNI_OK) {
1733     return ecode;
1734   }
1735 
1736   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1737                                                 DirtyCardQ_FL_lock,
1738                                                 (int)concurrent_refine()->yellow_zone(),
1739                                                 (int)concurrent_refine()->red_zone(),
1740                                                 Shared_DirtyCardQ_lock,
1741                                                 NULL,  // fl_owner
1742                                                 true); // init_free_ids
1743 
1744   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1745                                     DirtyCardQ_FL_lock,
1746                                     -1, // never trigger processing
1747                                     -1, // no limit on length
1748                                     Shared_DirtyCardQ_lock,
1749                                     &JavaThread::dirty_card_queue_set());
1750 
1751   // Here we allocate the dummy HeapRegion that is required by the
1752   // G1AllocRegion class.
1753   HeapRegion* dummy_region = _hrm.get_dummy_region();
1754 
1755   // We'll re-use the same region whether the alloc region will
1756   // require BOT updates or not and, if it doesn't, then a non-young
1757   // region will complain that it cannot support allocations without
1758   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1759   dummy_region->set_eden();
1760   // Make sure it's full.
1761   dummy_region->set_top(dummy_region->end());
1762   G1AllocRegion::setup(this, dummy_region);
1763 
1764   _allocator->init_mutator_alloc_region();
1765 
1766   // Do create of the monitoring and management support so that
1767   // values in the heap have been properly initialized.
1768   _g1mm = new G1MonitoringSupport(this);
1769 
1770   G1StringDedup::initialize();
1771 
1772   _preserved_marks_set.init(ParallelGCThreads);
1773 
1774   _collection_set.initialize(max_regions());
1775 
1776   return JNI_OK;
1777 }
1778 
1779 void G1CollectedHeap::initialize_serviceability() {
1780   _eden_pool = new G1EdenPool(this);
1781   _survivor_pool = new G1SurvivorPool(this);
1782   _old_pool = new G1OldGenPool(this);
1783 
1784   _full_gc_memory_manager.add_pool(_eden_pool);
1785   _full_gc_memory_manager.add_pool(_survivor_pool);
1786   _full_gc_memory_manager.add_pool(_old_pool);
1787 
1788   _memory_manager.add_pool(_eden_pool);
1789   _memory_manager.add_pool(_survivor_pool);
1790 
1791 }
1792 
1793 void G1CollectedHeap::stop() {
1794   // Stop all concurrent threads. We do this to make sure these threads
1795   // do not continue to execute and access resources (e.g. logging)
1796   // that are destroyed during shutdown.
1797   _cr->stop();
1798   _young_gen_sampling_thread->stop();
1799   _cmThread->stop();
1800   if (G1StringDedup::is_enabled()) {
1801     G1StringDedup::stop();
1802   }
1803 }
1804 
1805 void G1CollectedHeap::safepoint_synchronize_begin() {
1806   SuspendibleThreadSet::synchronize();
1807 }
1808 
1809 void G1CollectedHeap::safepoint_synchronize_end() {
1810   SuspendibleThreadSet::desynchronize();
1811 }
1812 
1813 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1814   return HeapRegion::max_region_size();
1815 }
1816 
1817 void G1CollectedHeap::post_initialize() {
1818   CollectedHeap::post_initialize();
1819   ref_processing_init();
1820 }
1821 
1822 void G1CollectedHeap::ref_processing_init() {
1823   // Reference processing in G1 currently works as follows:
1824   //
1825   // * There are two reference processor instances. One is
1826   //   used to record and process discovered references
1827   //   during concurrent marking; the other is used to
1828   //   record and process references during STW pauses
1829   //   (both full and incremental).
1830   // * Both ref processors need to 'span' the entire heap as
1831   //   the regions in the collection set may be dotted around.
1832   //
1833   // * For the concurrent marking ref processor:
1834   //   * Reference discovery is enabled at initial marking.
1835   //   * Reference discovery is disabled and the discovered
1836   //     references processed etc during remarking.
1837   //   * Reference discovery is MT (see below).
1838   //   * Reference discovery requires a barrier (see below).
1839   //   * Reference processing may or may not be MT
1840   //     (depending on the value of ParallelRefProcEnabled
1841   //     and ParallelGCThreads).
1842   //   * A full GC disables reference discovery by the CM
1843   //     ref processor and abandons any entries on it's
1844   //     discovered lists.
1845   //
1846   // * For the STW processor:
1847   //   * Non MT discovery is enabled at the start of a full GC.
1848   //   * Processing and enqueueing during a full GC is non-MT.
1849   //   * During a full GC, references are processed after marking.
1850   //
1851   //   * Discovery (may or may not be MT) is enabled at the start
1852   //     of an incremental evacuation pause.
1853   //   * References are processed near the end of a STW evacuation pause.
1854   //   * For both types of GC:
1855   //     * Discovery is atomic - i.e. not concurrent.
1856   //     * Reference discovery will not need a barrier.
1857 
1858   MemRegion mr = reserved_region();
1859 
1860   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1861 
1862   // Concurrent Mark ref processor
1863   _ref_processor_cm =
1864     new ReferenceProcessor(mr,    // span
1865                            mt_processing,
1866                                 // mt processing
1867                            ParallelGCThreads,
1868                                 // degree of mt processing
1869                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1870                                 // mt discovery
1871                            MAX2(ParallelGCThreads, ConcGCThreads),
1872                                 // degree of mt discovery
1873                            false,
1874                                 // Reference discovery is not atomic
1875                            &_is_alive_closure_cm);
1876                                 // is alive closure
1877                                 // (for efficiency/performance)
1878 
1879   // STW ref processor
1880   _ref_processor_stw =
1881     new ReferenceProcessor(mr,    // span
1882                            mt_processing,
1883                                 // mt processing
1884                            ParallelGCThreads,
1885                                 // degree of mt processing
1886                            (ParallelGCThreads > 1),
1887                                 // mt discovery
1888                            ParallelGCThreads,
1889                                 // degree of mt discovery
1890                            true,
1891                                 // Reference discovery is atomic
1892                            &_is_alive_closure_stw);
1893                                 // is alive closure
1894                                 // (for efficiency/performance)
1895 }
1896 
1897 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1898   return _collector_policy;
1899 }
1900 
1901 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1902   return &_soft_ref_policy;
1903 }
1904 
1905 size_t G1CollectedHeap::capacity() const {
1906   return _hrm.length() * HeapRegion::GrainBytes;
1907 }
1908 
1909 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1910   return _hrm.total_free_bytes();
1911 }
1912 
1913 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1914   hr->reset_gc_time_stamp();
1915 }
1916 
1917 #ifndef PRODUCT
1918 
1919 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1920 private:
1921   unsigned _gc_time_stamp;
1922   bool _failures;
1923 
1924 public:
1925   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1926     _gc_time_stamp(gc_time_stamp), _failures(false) { }
1927 
1928   virtual bool do_heap_region(HeapRegion* hr) {
1929     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1930     if (_gc_time_stamp != region_gc_time_stamp) {
1931       log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1932                             region_gc_time_stamp, _gc_time_stamp);
1933       _failures = true;
1934     }
1935     return false;
1936   }
1937 
1938   bool failures() { return _failures; }
1939 };
1940 
1941 void G1CollectedHeap::check_gc_time_stamps() {
1942   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1943   heap_region_iterate(&cl);
1944   guarantee(!cl.failures(), "all GC time stamps should have been reset");
1945 }
1946 #endif // PRODUCT
1947 
1948 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1949   _hot_card_cache->drain(cl, worker_i);
1950 }
1951 
1952 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1953   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1954   size_t n_completed_buffers = 0;
1955   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1956     n_completed_buffers++;
1957   }
1958   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1959   dcqs.clear_n_completed_buffers();
1960   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1961 }
1962 
1963 // Computes the sum of the storage used by the various regions.
1964 size_t G1CollectedHeap::used() const {
1965   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1966   if (_archive_allocator != NULL) {
1967     result += _archive_allocator->used();
1968   }
1969   return result;
1970 }
1971 
1972 size_t G1CollectedHeap::used_unlocked() const {
1973   return _summary_bytes_used;
1974 }
1975 
1976 class SumUsedClosure: public HeapRegionClosure {
1977   size_t _used;
1978 public:
1979   SumUsedClosure() : _used(0) {}
1980   bool do_heap_region(HeapRegion* r) {
1981     _used += r->used();
1982     return false;
1983   }
1984   size_t result() { return _used; }
1985 };
1986 
1987 size_t G1CollectedHeap::recalculate_used() const {
1988   double recalculate_used_start = os::elapsedTime();
1989 
1990   SumUsedClosure blk;
1991   heap_region_iterate(&blk);
1992 
1993   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1994   return blk.result();
1995 }
1996 
1997 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1998   switch (cause) {
1999     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2000     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2001     case GCCause::_wb_conc_mark:                        return true;
2002     default :                                           return false;
2003   }
2004 }
2005 
2006 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2007   switch (cause) {
2008     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2009     case GCCause::_g1_humongous_allocation: return true;
2010     default:                                return is_user_requested_concurrent_full_gc(cause);
2011   }
2012 }
2013 
2014 #ifndef PRODUCT
2015 void G1CollectedHeap::allocate_dummy_regions() {
2016   // Let's fill up most of the region
2017   size_t word_size = HeapRegion::GrainWords - 1024;
2018   // And as a result the region we'll allocate will be humongous.
2019   guarantee(is_humongous(word_size), "sanity");
2020 
2021   // _filler_array_max_size is set to humongous object threshold
2022   // but temporarily change it to use CollectedHeap::fill_with_object().
2023   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2024 
2025   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2026     // Let's use the existing mechanism for the allocation
2027     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2028                                                  AllocationContext::system());
2029     if (dummy_obj != NULL) {
2030       MemRegion mr(dummy_obj, word_size);
2031       CollectedHeap::fill_with_object(mr);
2032     } else {
2033       // If we can't allocate once, we probably cannot allocate
2034       // again. Let's get out of the loop.
2035       break;
2036     }
2037   }
2038 }
2039 #endif // !PRODUCT
2040 
2041 void G1CollectedHeap::increment_old_marking_cycles_started() {
2042   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2043          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2044          "Wrong marking cycle count (started: %d, completed: %d)",
2045          _old_marking_cycles_started, _old_marking_cycles_completed);
2046 
2047   _old_marking_cycles_started++;
2048 }
2049 
2050 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2051   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2052 
2053   // We assume that if concurrent == true, then the caller is a
2054   // concurrent thread that was joined the Suspendible Thread
2055   // Set. If there's ever a cheap way to check this, we should add an
2056   // assert here.
2057 
2058   // Given that this method is called at the end of a Full GC or of a
2059   // concurrent cycle, and those can be nested (i.e., a Full GC can
2060   // interrupt a concurrent cycle), the number of full collections
2061   // completed should be either one (in the case where there was no
2062   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2063   // behind the number of full collections started.
2064 
2065   // This is the case for the inner caller, i.e. a Full GC.
2066   assert(concurrent ||
2067          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2068          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2069          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2070          "is inconsistent with _old_marking_cycles_completed = %u",
2071          _old_marking_cycles_started, _old_marking_cycles_completed);
2072 
2073   // This is the case for the outer caller, i.e. the concurrent cycle.
2074   assert(!concurrent ||
2075          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2076          "for outer caller (concurrent cycle): "
2077          "_old_marking_cycles_started = %u "
2078          "is inconsistent with _old_marking_cycles_completed = %u",
2079          _old_marking_cycles_started, _old_marking_cycles_completed);
2080 
2081   _old_marking_cycles_completed += 1;
2082 
2083   // We need to clear the "in_progress" flag in the CM thread before
2084   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2085   // is set) so that if a waiter requests another System.gc() it doesn't
2086   // incorrectly see that a marking cycle is still in progress.
2087   if (concurrent) {
2088     _cmThread->set_idle();
2089   }
2090 
2091   // This notify_all() will ensure that a thread that called
2092   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2093   // and it's waiting for a full GC to finish will be woken up. It is
2094   // waiting in VM_G1CollectForAllocation::doit_epilogue().
2095   FullGCCount_lock->notify_all();
2096 }
2097 
2098 void G1CollectedHeap::collect(GCCause::Cause cause) {
2099   assert_heap_not_locked();
2100 
2101   uint gc_count_before;
2102   uint old_marking_count_before;
2103   uint full_gc_count_before;
2104   bool retry_gc;
2105 
2106   do {
2107     retry_gc = false;
2108 
2109     {
2110       MutexLocker ml(Heap_lock);
2111 
2112       // Read the GC count while holding the Heap_lock
2113       gc_count_before = total_collections();
2114       full_gc_count_before = total_full_collections();
2115       old_marking_count_before = _old_marking_cycles_started;
2116     }
2117 
2118     if (should_do_concurrent_full_gc(cause)) {
2119       // Schedule an initial-mark evacuation pause that will start a
2120       // concurrent cycle. We're setting word_size to 0 which means that
2121       // we are not requesting a post-GC allocation.
2122       VM_G1CollectForAllocation op(0,     /* word_size */
2123                                    gc_count_before,
2124                                    cause,
2125                                    true,  /* should_initiate_conc_mark */
2126                                    g1_policy()->max_pause_time_ms(),
2127                                    AllocationContext::current());
2128       VMThread::execute(&op);
2129       if (!op.pause_succeeded()) {
2130         if (old_marking_count_before == _old_marking_cycles_started) {
2131           retry_gc = op.should_retry_gc();
2132         } else {
2133           // A Full GC happened while we were trying to schedule the
2134           // initial-mark GC. No point in starting a new cycle given
2135           // that the whole heap was collected anyway.
2136         }
2137 
2138         if (retry_gc) {
2139           if (GCLocker::is_active_and_needs_gc()) {
2140             GCLocker::stall_until_clear();
2141           }
2142         }
2143       }
2144     } else {
2145       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2146           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2147 
2148         // Schedule a standard evacuation pause. We're setting word_size
2149         // to 0 which means that we are not requesting a post-GC allocation.
2150         VM_G1CollectForAllocation op(0,     /* word_size */
2151                                      gc_count_before,
2152                                      cause,
2153                                      false, /* should_initiate_conc_mark */
2154                                      g1_policy()->max_pause_time_ms(),
2155                                      AllocationContext::current());
2156         VMThread::execute(&op);
2157       } else {
2158         // Schedule a Full GC.
2159         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2160         VMThread::execute(&op);
2161       }
2162     }
2163   } while (retry_gc);
2164 }
2165 
2166 bool G1CollectedHeap::is_in(const void* p) const {
2167   if (_hrm.reserved().contains(p)) {
2168     // Given that we know that p is in the reserved space,
2169     // heap_region_containing() should successfully
2170     // return the containing region.
2171     HeapRegion* hr = heap_region_containing(p);
2172     return hr->is_in(p);
2173   } else {
2174     return false;
2175   }
2176 }
2177 
2178 #ifdef ASSERT
2179 bool G1CollectedHeap::is_in_exact(const void* p) const {
2180   bool contains = reserved_region().contains(p);
2181   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2182   if (contains && available) {
2183     return true;
2184   } else {
2185     return false;
2186   }
2187 }
2188 #endif
2189 
2190 // Iteration functions.
2191 
2192 // Iterates an ObjectClosure over all objects within a HeapRegion.
2193 
2194 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2195   ObjectClosure* _cl;
2196 public:
2197   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2198   bool do_heap_region(HeapRegion* r) {
2199     if (!r->is_continues_humongous()) {
2200       r->object_iterate(_cl);
2201     }
2202     return false;
2203   }
2204 };
2205 
2206 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2207   IterateObjectClosureRegionClosure blk(cl);
2208   heap_region_iterate(&blk);
2209 }
2210 
2211 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2212   _hrm.iterate(cl);
2213 }
2214 
2215 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2216                                                                  HeapRegionClaimer *hrclaimer,
2217                                                                  uint worker_id) const {
2218   _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2219 }
2220 
2221 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2222                                                          HeapRegionClaimer *hrclaimer) const {
2223   _hrm.par_iterate(cl, hrclaimer, 0);
2224 }
2225 
2226 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2227   _collection_set.iterate(cl);
2228 }
2229 
2230 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2231   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2232 }
2233 
2234 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2235   HeapRegion* hr = heap_region_containing(addr);
2236   return hr->block_start(addr);
2237 }
2238 
2239 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2240   HeapRegion* hr = heap_region_containing(addr);
2241   return hr->block_size(addr);
2242 }
2243 
2244 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2245   HeapRegion* hr = heap_region_containing(addr);
2246   return hr->block_is_obj(addr);
2247 }
2248 
2249 bool G1CollectedHeap::supports_tlab_allocation() const {
2250   return true;
2251 }
2252 
2253 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2254   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2255 }
2256 
2257 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2258   return _eden.length() * HeapRegion::GrainBytes;
2259 }
2260 
2261 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2262 // must be equal to the humongous object limit.
2263 size_t G1CollectedHeap::max_tlab_size() const {
2264   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2265 }
2266 
2267 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2268   AllocationContext_t context = AllocationContext::current();
2269   return _allocator->unsafe_max_tlab_alloc(context);
2270 }
2271 
2272 size_t G1CollectedHeap::max_capacity() const {
2273   return _hrm.reserved().byte_size();
2274 }
2275 
2276 jlong G1CollectedHeap::millis_since_last_gc() {
2277   // See the notes in GenCollectedHeap::millis_since_last_gc()
2278   // for more information about the implementation.
2279   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2280     _g1_policy->collection_pause_end_millis();
2281   if (ret_val < 0) {
2282     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2283       ". returning zero instead.", ret_val);
2284     return 0;
2285   }
2286   return ret_val;
2287 }
2288 
2289 void G1CollectedHeap::prepare_for_verify() {
2290   _verifier->prepare_for_verify();
2291 }
2292 
2293 void G1CollectedHeap::verify(VerifyOption vo) {
2294   _verifier->verify(vo);
2295 }
2296 
2297 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2298   return true;
2299 }
2300 
2301 const char* const* G1CollectedHeap::concurrent_phases() const {
2302   return _cmThread->concurrent_phases();
2303 }
2304 
2305 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2306   return _cmThread->request_concurrent_phase(phase);
2307 }
2308 
2309 class PrintRegionClosure: public HeapRegionClosure {
2310   outputStream* _st;
2311 public:
2312   PrintRegionClosure(outputStream* st) : _st(st) {}
2313   bool do_heap_region(HeapRegion* r) {
2314     r->print_on(_st);
2315     return false;
2316   }
2317 };
2318 
2319 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2320                                        const HeapRegion* hr,
2321                                        const VerifyOption vo) const {
2322   switch (vo) {
2323   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2324   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2325   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2326   default:                            ShouldNotReachHere();
2327   }
2328   return false; // keep some compilers happy
2329 }
2330 
2331 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2332                                        const VerifyOption vo) const {
2333   switch (vo) {
2334   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2335   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2336   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2337   default:                            ShouldNotReachHere();
2338   }
2339   return false; // keep some compilers happy
2340 }
2341 
2342 void G1CollectedHeap::print_heap_regions() const {
2343   LogTarget(Trace, gc, heap, region) lt;
2344   if (lt.is_enabled()) {
2345     LogStream ls(lt);
2346     print_regions_on(&ls);
2347   }
2348 }
2349 
2350 void G1CollectedHeap::print_on(outputStream* st) const {
2351   st->print(" %-20s", "garbage-first heap");
2352   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2353             capacity()/K, used_unlocked()/K);
2354   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2355             p2i(_hrm.reserved().start()),
2356             p2i(_hrm.reserved().end()));
2357   st->cr();
2358   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2359   uint young_regions = young_regions_count();
2360   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2361             (size_t) young_regions * HeapRegion::GrainBytes / K);
2362   uint survivor_regions = survivor_regions_count();
2363   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2364             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2365   st->cr();
2366   MetaspaceAux::print_on(st);
2367 }
2368 
2369 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2370   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2371                "HS=humongous(starts), HC=humongous(continues), "
2372                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2373                "AC=allocation context, "
2374                "TAMS=top-at-mark-start (previous, next)");
2375   PrintRegionClosure blk(st);
2376   heap_region_iterate(&blk);
2377 }
2378 
2379 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2380   print_on(st);
2381 
2382   // Print the per-region information.
2383   print_regions_on(st);
2384 }
2385 
2386 void G1CollectedHeap::print_on_error(outputStream* st) const {
2387   this->CollectedHeap::print_on_error(st);
2388 
2389   if (_cm != NULL) {
2390     st->cr();
2391     _cm->print_on_error(st);
2392   }
2393 }
2394 
2395 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2396   workers()->print_worker_threads_on(st);
2397   _cmThread->print_on(st);
2398   st->cr();
2399   _cm->print_worker_threads_on(st);
2400   _cr->print_threads_on(st);
2401   _young_gen_sampling_thread->print_on(st);
2402   if (G1StringDedup::is_enabled()) {
2403     G1StringDedup::print_worker_threads_on(st);
2404   }
2405 }
2406 
2407 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2408   workers()->threads_do(tc);
2409   tc->do_thread(_cmThread);
2410   _cm->threads_do(tc);
2411   _cr->threads_do(tc);
2412   tc->do_thread(_young_gen_sampling_thread);
2413   if (G1StringDedup::is_enabled()) {
2414     G1StringDedup::threads_do(tc);
2415   }
2416 }
2417 
2418 void G1CollectedHeap::print_tracing_info() const {
2419   g1_rem_set()->print_summary_info();
2420   concurrent_mark()->print_summary_info();
2421 }
2422 
2423 #ifndef PRODUCT
2424 // Helpful for debugging RSet issues.
2425 
2426 class PrintRSetsClosure : public HeapRegionClosure {
2427 private:
2428   const char* _msg;
2429   size_t _occupied_sum;
2430 
2431 public:
2432   bool do_heap_region(HeapRegion* r) {
2433     HeapRegionRemSet* hrrs = r->rem_set();
2434     size_t occupied = hrrs->occupied();
2435     _occupied_sum += occupied;
2436 
2437     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2438     if (occupied == 0) {
2439       tty->print_cr("  RSet is empty");
2440     } else {
2441       hrrs->print();
2442     }
2443     tty->print_cr("----------");
2444     return false;
2445   }
2446 
2447   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2448     tty->cr();
2449     tty->print_cr("========================================");
2450     tty->print_cr("%s", msg);
2451     tty->cr();
2452   }
2453 
2454   ~PrintRSetsClosure() {
2455     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2456     tty->print_cr("========================================");
2457     tty->cr();
2458   }
2459 };
2460 
2461 void G1CollectedHeap::print_cset_rsets() {
2462   PrintRSetsClosure cl("Printing CSet RSets");
2463   collection_set_iterate(&cl);
2464 }
2465 
2466 void G1CollectedHeap::print_all_rsets() {
2467   PrintRSetsClosure cl("Printing All RSets");;
2468   heap_region_iterate(&cl);
2469 }
2470 #endif // PRODUCT
2471 
2472 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2473 
2474   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2475   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2476   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2477 
2478   size_t eden_capacity_bytes =
2479     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2480 
2481   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2482   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2483                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2484 }
2485 
2486 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2487   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2488                        stats->unused(), stats->used(), stats->region_end_waste(),
2489                        stats->regions_filled(), stats->direct_allocated(),
2490                        stats->failure_used(), stats->failure_waste());
2491 }
2492 
2493 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2494   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2495   gc_tracer->report_gc_heap_summary(when, heap_summary);
2496 
2497   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2498   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2499 }
2500 
2501 G1CollectedHeap* G1CollectedHeap::heap() {
2502   CollectedHeap* heap = Universe::heap();
2503   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2504   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2505   return (G1CollectedHeap*)heap;
2506 }
2507 
2508 void G1CollectedHeap::gc_prologue(bool full) {
2509   // always_do_update_barrier = false;
2510   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2511 
2512   // This summary needs to be printed before incrementing total collections.
2513   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2514 
2515   // Update common counters.
2516   increment_total_collections(full /* full gc */);
2517   if (full) {
2518     increment_old_marking_cycles_started();
2519     reset_gc_time_stamp();
2520   } else {
2521     increment_gc_time_stamp();
2522   }
2523 
2524   // Fill TLAB's and such
2525   double start = os::elapsedTime();
2526   accumulate_statistics_all_tlabs();
2527   ensure_parsability(true);
2528   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2529 }
2530 
2531 void G1CollectedHeap::gc_epilogue(bool full) {
2532   // Update common counters.
2533   if (full) {
2534     // Update the number of full collections that have been completed.
2535     increment_old_marking_cycles_completed(false /* concurrent */);
2536   }
2537 
2538   // We are at the end of the GC. Total collections has already been increased.
2539   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2540 
2541   // FIXME: what is this about?
2542   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2543   // is set.
2544 #if COMPILER2_OR_JVMCI
2545   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2546 #endif
2547   // always_do_update_barrier = true;
2548 
2549   double start = os::elapsedTime();
2550   resize_all_tlabs();
2551   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2552 
2553   MemoryService::track_memory_usage();
2554   // We have just completed a GC. Update the soft reference
2555   // policy with the new heap occupancy
2556   Universe::update_heap_info_at_gc();
2557 }
2558 
2559 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2560                                                uint gc_count_before,
2561                                                bool* succeeded,
2562                                                GCCause::Cause gc_cause) {
2563   assert_heap_not_locked_and_not_at_safepoint();
2564   VM_G1CollectForAllocation op(word_size,
2565                                gc_count_before,
2566                                gc_cause,
2567                                false, /* should_initiate_conc_mark */
2568                                g1_policy()->max_pause_time_ms(),
2569                                AllocationContext::current());
2570   VMThread::execute(&op);
2571 
2572   HeapWord* result = op.result();
2573   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2574   assert(result == NULL || ret_succeeded,
2575          "the result should be NULL if the VM did not succeed");
2576   *succeeded = ret_succeeded;
2577 
2578   assert_heap_not_locked();
2579   return result;
2580 }
2581 
2582 void
2583 G1CollectedHeap::doConcurrentMark() {
2584   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2585   if (!_cmThread->in_progress()) {
2586     _cmThread->set_started();
2587     CGC_lock->notify();
2588   }
2589 }
2590 
2591 size_t G1CollectedHeap::pending_card_num() {
2592   size_t extra_cards = 0;
2593   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2594     DirtyCardQueue& dcq = curr->dirty_card_queue();
2595     extra_cards += dcq.size();
2596   }
2597   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2598   size_t buffer_size = dcqs.buffer_size();
2599   size_t buffer_num = dcqs.completed_buffers_num();
2600 
2601   return buffer_size * buffer_num + extra_cards;
2602 }
2603 
2604 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2605  private:
2606   size_t _total_humongous;
2607   size_t _candidate_humongous;
2608 
2609   DirtyCardQueue _dcq;
2610 
2611   // We don't nominate objects with many remembered set entries, on
2612   // the assumption that such objects are likely still live.
2613   bool is_remset_small(HeapRegion* region) const {
2614     HeapRegionRemSet* const rset = region->rem_set();
2615     return G1EagerReclaimHumongousObjectsWithStaleRefs
2616       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2617       : rset->is_empty();
2618   }
2619 
2620   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2621     assert(region->is_starts_humongous(), "Must start a humongous object");
2622 
2623     oop obj = oop(region->bottom());
2624 
2625     // Dead objects cannot be eager reclaim candidates. Due to class
2626     // unloading it is unsafe to query their classes so we return early.
2627     if (heap->is_obj_dead(obj, region)) {
2628       return false;
2629     }
2630 
2631     // Candidate selection must satisfy the following constraints
2632     // while concurrent marking is in progress:
2633     //
2634     // * In order to maintain SATB invariants, an object must not be
2635     // reclaimed if it was allocated before the start of marking and
2636     // has not had its references scanned.  Such an object must have
2637     // its references (including type metadata) scanned to ensure no
2638     // live objects are missed by the marking process.  Objects
2639     // allocated after the start of concurrent marking don't need to
2640     // be scanned.
2641     //
2642     // * An object must not be reclaimed if it is on the concurrent
2643     // mark stack.  Objects allocated after the start of concurrent
2644     // marking are never pushed on the mark stack.
2645     //
2646     // Nominating only objects allocated after the start of concurrent
2647     // marking is sufficient to meet both constraints.  This may miss
2648     // some objects that satisfy the constraints, but the marking data
2649     // structures don't support efficiently performing the needed
2650     // additional tests or scrubbing of the mark stack.
2651     //
2652     // However, we presently only nominate is_typeArray() objects.
2653     // A humongous object containing references induces remembered
2654     // set entries on other regions.  In order to reclaim such an
2655     // object, those remembered sets would need to be cleaned up.
2656     //
2657     // We also treat is_typeArray() objects specially, allowing them
2658     // to be reclaimed even if allocated before the start of
2659     // concurrent mark.  For this we rely on mark stack insertion to
2660     // exclude is_typeArray() objects, preventing reclaiming an object
2661     // that is in the mark stack.  We also rely on the metadata for
2662     // such objects to be built-in and so ensured to be kept live.
2663     // Frequent allocation and drop of large binary blobs is an
2664     // important use case for eager reclaim, and this special handling
2665     // may reduce needed headroom.
2666 
2667     return obj->is_typeArray() && is_remset_small(region);
2668   }
2669 
2670  public:
2671   RegisterHumongousWithInCSetFastTestClosure()
2672   : _total_humongous(0),
2673     _candidate_humongous(0),
2674     _dcq(&JavaThread::dirty_card_queue_set()) {
2675   }
2676 
2677   virtual bool do_heap_region(HeapRegion* r) {
2678     if (!r->is_starts_humongous()) {
2679       return false;
2680     }
2681     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2682 
2683     bool is_candidate = humongous_region_is_candidate(g1h, r);
2684     uint rindex = r->hrm_index();
2685     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2686     if (is_candidate) {
2687       _candidate_humongous++;
2688       g1h->register_humongous_region_with_cset(rindex);
2689       // Is_candidate already filters out humongous object with large remembered sets.
2690       // If we have a humongous object with a few remembered sets, we simply flush these
2691       // remembered set entries into the DCQS. That will result in automatic
2692       // re-evaluation of their remembered set entries during the following evacuation
2693       // phase.
2694       if (!r->rem_set()->is_empty()) {
2695         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2696                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2697         G1CardTable* ct = g1h->card_table();
2698         HeapRegionRemSetIterator hrrs(r->rem_set());
2699         size_t card_index;
2700         while (hrrs.has_next(card_index)) {
2701           jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2702           // The remembered set might contain references to already freed
2703           // regions. Filter out such entries to avoid failing card table
2704           // verification.
2705           if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2706             if (*card_ptr != G1CardTable::dirty_card_val()) {
2707               *card_ptr = G1CardTable::dirty_card_val();
2708               _dcq.enqueue(card_ptr);
2709             }
2710           }
2711         }
2712         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2713                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2714                hrrs.n_yielded(), r->rem_set()->occupied());
2715         r->rem_set()->clear_locked();
2716       }
2717       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2718     }
2719     _total_humongous++;
2720 
2721     return false;
2722   }
2723 
2724   size_t total_humongous() const { return _total_humongous; }
2725   size_t candidate_humongous() const { return _candidate_humongous; }
2726 
2727   void flush_rem_set_entries() { _dcq.flush(); }
2728 };
2729 
2730 void G1CollectedHeap::register_humongous_regions_with_cset() {
2731   if (!G1EagerReclaimHumongousObjects) {
2732     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2733     return;
2734   }
2735   double time = os::elapsed_counter();
2736 
2737   // Collect reclaim candidate information and register candidates with cset.
2738   RegisterHumongousWithInCSetFastTestClosure cl;
2739   heap_region_iterate(&cl);
2740 
2741   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2742   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2743                                                                   cl.total_humongous(),
2744                                                                   cl.candidate_humongous());
2745   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2746 
2747   // Finally flush all remembered set entries to re-check into the global DCQS.
2748   cl.flush_rem_set_entries();
2749 }
2750 
2751 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2752   public:
2753     bool do_heap_region(HeapRegion* hr) {
2754       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2755         hr->verify_rem_set();
2756       }
2757       return false;
2758     }
2759 };
2760 
2761 uint G1CollectedHeap::num_task_queues() const {
2762   return _task_queues->size();
2763 }
2764 
2765 #if TASKQUEUE_STATS
2766 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2767   st->print_raw_cr("GC Task Stats");
2768   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2769   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2770 }
2771 
2772 void G1CollectedHeap::print_taskqueue_stats() const {
2773   if (!log_is_enabled(Trace, gc, task, stats)) {
2774     return;
2775   }
2776   Log(gc, task, stats) log;
2777   ResourceMark rm;
2778   LogStream ls(log.trace());
2779   outputStream* st = &ls;
2780 
2781   print_taskqueue_stats_hdr(st);
2782 
2783   TaskQueueStats totals;
2784   const uint n = num_task_queues();
2785   for (uint i = 0; i < n; ++i) {
2786     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2787     totals += task_queue(i)->stats;
2788   }
2789   st->print_raw("tot "); totals.print(st); st->cr();
2790 
2791   DEBUG_ONLY(totals.verify());
2792 }
2793 
2794 void G1CollectedHeap::reset_taskqueue_stats() {
2795   const uint n = num_task_queues();
2796   for (uint i = 0; i < n; ++i) {
2797     task_queue(i)->stats.reset();
2798   }
2799 }
2800 #endif // TASKQUEUE_STATS
2801 
2802 void G1CollectedHeap::wait_for_root_region_scanning() {
2803   double scan_wait_start = os::elapsedTime();
2804   // We have to wait until the CM threads finish scanning the
2805   // root regions as it's the only way to ensure that all the
2806   // objects on them have been correctly scanned before we start
2807   // moving them during the GC.
2808   bool waited = _cm->root_regions()->wait_until_scan_finished();
2809   double wait_time_ms = 0.0;
2810   if (waited) {
2811     double scan_wait_end = os::elapsedTime();
2812     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2813   }
2814   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2815 }
2816 
2817 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2818 private:
2819   G1HRPrinter* _hr_printer;
2820 public:
2821   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2822 
2823   virtual bool do_heap_region(HeapRegion* r) {
2824     _hr_printer->cset(r);
2825     return false;
2826   }
2827 };
2828 
2829 void G1CollectedHeap::start_new_collection_set() {
2830   collection_set()->start_incremental_building();
2831 
2832   clear_cset_fast_test();
2833 
2834   guarantee(_eden.length() == 0, "eden should have been cleared");
2835   g1_policy()->transfer_survivors_to_cset(survivor());
2836 }
2837 
2838 bool
2839 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2840   assert_at_safepoint(true /* should_be_vm_thread */);
2841   guarantee(!is_gc_active(), "collection is not reentrant");
2842 
2843   if (GCLocker::check_active_before_gc()) {
2844     return false;
2845   }
2846 
2847   _gc_timer_stw->register_gc_start();
2848 
2849   GCIdMark gc_id_mark;
2850   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2851 
2852   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2853   ResourceMark rm;
2854 
2855   g1_policy()->note_gc_start();
2856 
2857   wait_for_root_region_scanning();
2858 
2859   print_heap_before_gc();
2860   print_heap_regions();
2861   trace_heap_before_gc(_gc_tracer_stw);
2862 
2863   _verifier->verify_region_sets_optional();
2864   _verifier->verify_dirty_young_regions();
2865 
2866   // We should not be doing initial mark unless the conc mark thread is running
2867   if (!_cmThread->should_terminate()) {
2868     // This call will decide whether this pause is an initial-mark
2869     // pause. If it is, during_initial_mark_pause() will return true
2870     // for the duration of this pause.
2871     g1_policy()->decide_on_conc_mark_initiation();
2872   }
2873 
2874   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2875   assert(!collector_state()->during_initial_mark_pause() ||
2876           collector_state()->gcs_are_young(), "sanity");
2877 
2878   // We also do not allow mixed GCs during marking.
2879   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2880 
2881   // Record whether this pause is an initial mark. When the current
2882   // thread has completed its logging output and it's safe to signal
2883   // the CM thread, the flag's value in the policy has been reset.
2884   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2885 
2886   // Inner scope for scope based logging, timers, and stats collection
2887   {
2888     EvacuationInfo evacuation_info;
2889 
2890     if (collector_state()->during_initial_mark_pause()) {
2891       // We are about to start a marking cycle, so we increment the
2892       // full collection counter.
2893       increment_old_marking_cycles_started();
2894       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2895     }
2896 
2897     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2898 
2899     GCTraceCPUTime tcpu;
2900 
2901     G1HeapVerifier::G1VerifyType verify_type;
2902     FormatBuffer<> gc_string("Pause ");
2903     if (collector_state()->during_initial_mark_pause()) {
2904       gc_string.append("Initial Mark");
2905       verify_type = G1HeapVerifier::G1VerifyInitialMark;
2906     } else if (collector_state()->gcs_are_young()) {
2907       gc_string.append("Young");
2908       verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2909     } else {
2910       gc_string.append("Mixed");
2911       verify_type = G1HeapVerifier::G1VerifyMixed;
2912     }
2913     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2914 
2915     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2916                                                                   workers()->active_workers(),
2917                                                                   Threads::number_of_non_daemon_threads());
2918     workers()->update_active_workers(active_workers);
2919     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2920 
2921     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2922     TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2923 
2924     // If the secondary_free_list is not empty, append it to the
2925     // free_list. No need to wait for the cleanup operation to finish;
2926     // the region allocation code will check the secondary_free_list
2927     // and wait if necessary. If the G1StressConcRegionFreeing flag is
2928     // set, skip this step so that the region allocation code has to
2929     // get entries from the secondary_free_list.
2930     if (!G1StressConcRegionFreeing) {
2931       append_secondary_free_list_if_not_empty_with_lock();
2932     }
2933 
2934     G1HeapTransition heap_transition(this);
2935     size_t heap_used_bytes_before_gc = used();
2936 
2937     // Don't dynamically change the number of GC threads this early.  A value of
2938     // 0 is used to indicate serial work.  When parallel work is done,
2939     // it will be set.
2940 
2941     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2942       IsGCActiveMark x;
2943 
2944       gc_prologue(false);
2945 
2946       if (VerifyRememberedSets) {
2947         log_info(gc, verify)("[Verifying RemSets before GC]");
2948         VerifyRegionRemSetClosure v_cl;
2949         heap_region_iterate(&v_cl);
2950       }
2951 
2952       _verifier->verify_before_gc(verify_type);
2953 
2954       _verifier->check_bitmaps("GC Start");
2955 
2956 #if COMPILER2_OR_JVMCI
2957       DerivedPointerTable::clear();
2958 #endif
2959 
2960       // Please see comment in g1CollectedHeap.hpp and
2961       // G1CollectedHeap::ref_processing_init() to see how
2962       // reference processing currently works in G1.
2963 
2964       // Enable discovery in the STW reference processor
2965       if (g1_policy()->should_process_references()) {
2966         ref_processor_stw()->enable_discovery();
2967       } else {
2968         ref_processor_stw()->disable_discovery();
2969       }
2970 
2971       {
2972         // We want to temporarily turn off discovery by the
2973         // CM ref processor, if necessary, and turn it back on
2974         // on again later if we do. Using a scoped
2975         // NoRefDiscovery object will do this.
2976         NoRefDiscovery no_cm_discovery(ref_processor_cm());
2977 
2978         // Forget the current alloc region (we might even choose it to be part
2979         // of the collection set!).
2980         _allocator->release_mutator_alloc_region();
2981 
2982         // This timing is only used by the ergonomics to handle our pause target.
2983         // It is unclear why this should not include the full pause. We will
2984         // investigate this in CR 7178365.
2985         //
2986         // Preserving the old comment here if that helps the investigation:
2987         //
2988         // The elapsed time induced by the start time below deliberately elides
2989         // the possible verification above.
2990         double sample_start_time_sec = os::elapsedTime();
2991 
2992         g1_policy()->record_collection_pause_start(sample_start_time_sec);
2993 
2994         if (collector_state()->during_initial_mark_pause()) {
2995           concurrent_mark()->checkpoint_roots_initial_pre();
2996         }
2997 
2998         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2999 
3000         evacuation_info.set_collectionset_regions(collection_set()->region_length());
3001 
3002         // Make sure the remembered sets are up to date. This needs to be
3003         // done before register_humongous_regions_with_cset(), because the
3004         // remembered sets are used there to choose eager reclaim candidates.
3005         // If the remembered sets are not up to date we might miss some
3006         // entries that need to be handled.
3007         g1_rem_set()->cleanupHRRS();
3008 
3009         register_humongous_regions_with_cset();
3010 
3011         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3012 
3013         // We call this after finalize_cset() to
3014         // ensure that the CSet has been finalized.
3015         _cm->verify_no_cset_oops();
3016 
3017         if (_hr_printer.is_active()) {
3018           G1PrintCollectionSetClosure cl(&_hr_printer);
3019           _collection_set.iterate(&cl);
3020         }
3021 
3022         // Initialize the GC alloc regions.
3023         _allocator->init_gc_alloc_regions(evacuation_info);
3024 
3025         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3026         pre_evacuate_collection_set();
3027 
3028         // Actually do the work...
3029         evacuate_collection_set(evacuation_info, &per_thread_states);
3030 
3031         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3032 
3033         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3034         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3035 
3036         eagerly_reclaim_humongous_regions();
3037 
3038         record_obj_copy_mem_stats();
3039         _survivor_evac_stats.adjust_desired_plab_sz();
3040         _old_evac_stats.adjust_desired_plab_sz();
3041 
3042         double start = os::elapsedTime();
3043         start_new_collection_set();
3044         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3045 
3046         if (evacuation_failed()) {
3047           set_used(recalculate_used());
3048           if (_archive_allocator != NULL) {
3049             _archive_allocator->clear_used();
3050           }
3051           for (uint i = 0; i < ParallelGCThreads; i++) {
3052             if (_evacuation_failed_info_array[i].has_failed()) {
3053               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3054             }
3055           }
3056         } else {
3057           // The "used" of the the collection set have already been subtracted
3058           // when they were freed.  Add in the bytes evacuated.
3059           increase_used(g1_policy()->bytes_copied_during_gc());
3060         }
3061 
3062         if (collector_state()->during_initial_mark_pause()) {
3063           // We have to do this before we notify the CM threads that
3064           // they can start working to make sure that all the
3065           // appropriate initialization is done on the CM object.
3066           concurrent_mark()->checkpoint_roots_initial_post();
3067           collector_state()->set_mark_in_progress(true);
3068           // Note that we don't actually trigger the CM thread at
3069           // this point. We do that later when we're sure that
3070           // the current thread has completed its logging output.
3071         }
3072 
3073         allocate_dummy_regions();
3074 
3075         _allocator->init_mutator_alloc_region();
3076 
3077         {
3078           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3079           if (expand_bytes > 0) {
3080             size_t bytes_before = capacity();
3081             // No need for an ergo logging here,
3082             // expansion_amount() does this when it returns a value > 0.
3083             double expand_ms;
3084             if (!expand(expand_bytes, _workers, &expand_ms)) {
3085               // We failed to expand the heap. Cannot do anything about it.
3086             }
3087             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3088           }
3089         }
3090 
3091         // We redo the verification but now wrt to the new CSet which
3092         // has just got initialized after the previous CSet was freed.
3093         _cm->verify_no_cset_oops();
3094 
3095         // This timing is only used by the ergonomics to handle our pause target.
3096         // It is unclear why this should not include the full pause. We will
3097         // investigate this in CR 7178365.
3098         double sample_end_time_sec = os::elapsedTime();
3099         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3100         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3101         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3102 
3103         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3104         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3105 
3106         if (VerifyRememberedSets) {
3107           log_info(gc, verify)("[Verifying RemSets after GC]");
3108           VerifyRegionRemSetClosure v_cl;
3109           heap_region_iterate(&v_cl);
3110         }
3111 
3112         _verifier->verify_after_gc(verify_type);
3113         _verifier->check_bitmaps("GC End");
3114 
3115         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3116         ref_processor_stw()->verify_no_references_recorded();
3117 
3118         // CM reference discovery will be re-enabled if necessary.
3119       }
3120 
3121 #ifdef TRACESPINNING
3122       ParallelTaskTerminator::print_termination_counts();
3123 #endif
3124 
3125       gc_epilogue(false);
3126     }
3127 
3128     // Print the remainder of the GC log output.
3129     if (evacuation_failed()) {
3130       log_info(gc)("To-space exhausted");
3131     }
3132 
3133     g1_policy()->print_phases();
3134     heap_transition.print();
3135 
3136     // It is not yet to safe to tell the concurrent mark to
3137     // start as we have some optional output below. We don't want the
3138     // output from the concurrent mark thread interfering with this
3139     // logging output either.
3140 
3141     _hrm.verify_optional();
3142     _verifier->verify_region_sets_optional();
3143 
3144     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3145     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3146 
3147     print_heap_after_gc();
3148     print_heap_regions();
3149     trace_heap_after_gc(_gc_tracer_stw);
3150 
3151     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3152     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3153     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3154     // before any GC notifications are raised.
3155     g1mm()->update_sizes();
3156 
3157     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3158     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3159     _gc_timer_stw->register_gc_end();
3160     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3161   }
3162   // It should now be safe to tell the concurrent mark thread to start
3163   // without its logging output interfering with the logging output
3164   // that came from the pause.
3165 
3166   if (should_start_conc_mark) {
3167     // CAUTION: after the doConcurrentMark() call below,
3168     // the concurrent marking thread(s) could be running
3169     // concurrently with us. Make sure that anything after
3170     // this point does not assume that we are the only GC thread
3171     // running. Note: of course, the actual marking work will
3172     // not start until the safepoint itself is released in
3173     // SuspendibleThreadSet::desynchronize().
3174     doConcurrentMark();
3175   }
3176 
3177   return true;
3178 }
3179 
3180 void G1CollectedHeap::remove_self_forwarding_pointers() {
3181   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3182   workers()->run_task(&rsfp_task);
3183 }
3184 
3185 void G1CollectedHeap::restore_after_evac_failure() {
3186   double remove_self_forwards_start = os::elapsedTime();
3187 
3188   remove_self_forwarding_pointers();
3189   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3190   _preserved_marks_set.restore(&task_executor);
3191 
3192   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3193 }
3194 
3195 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3196   if (!_evacuation_failed) {
3197     _evacuation_failed = true;
3198   }
3199 
3200   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3201   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3202 }
3203 
3204 bool G1ParEvacuateFollowersClosure::offer_termination() {
3205   G1ParScanThreadState* const pss = par_scan_state();
3206   start_term_time();
3207   const bool res = terminator()->offer_termination();
3208   end_term_time();
3209   return res;
3210 }
3211 
3212 void G1ParEvacuateFollowersClosure::do_void() {
3213   G1ParScanThreadState* const pss = par_scan_state();
3214   pss->trim_queue();
3215   do {
3216     pss->steal_and_trim_queue(queues());
3217   } while (!offer_termination());
3218 }
3219 
3220 class G1ParTask : public AbstractGangTask {
3221 protected:
3222   G1CollectedHeap*         _g1h;
3223   G1ParScanThreadStateSet* _pss;
3224   RefToScanQueueSet*       _queues;
3225   G1RootProcessor*         _root_processor;
3226   ParallelTaskTerminator   _terminator;
3227   uint                     _n_workers;
3228 
3229 public:
3230   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3231     : AbstractGangTask("G1 collection"),
3232       _g1h(g1h),
3233       _pss(per_thread_states),
3234       _queues(task_queues),
3235       _root_processor(root_processor),
3236       _terminator(n_workers, _queues),
3237       _n_workers(n_workers)
3238   {}
3239 
3240   void work(uint worker_id) {
3241     if (worker_id >= _n_workers) return;  // no work needed this round
3242 
3243     double start_sec = os::elapsedTime();
3244     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3245 
3246     {
3247       ResourceMark rm;
3248       HandleMark   hm;
3249 
3250       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3251 
3252       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3253       pss->set_ref_processor(rp);
3254 
3255       double start_strong_roots_sec = os::elapsedTime();
3256 
3257       _root_processor->evacuate_roots(pss->closures(), worker_id);
3258 
3259       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3260       // treating the nmethods visited to act as roots for concurrent marking.
3261       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3262       // objects copied by the current evacuation.
3263       _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3264                                                       pss->closures()->weak_codeblobs(),
3265                                                       worker_id);
3266 
3267       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3268 
3269       double term_sec = 0.0;
3270       size_t evac_term_attempts = 0;
3271       {
3272         double start = os::elapsedTime();
3273         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3274         evac.do_void();
3275 
3276         evac_term_attempts = evac.term_attempts();
3277         term_sec = evac.term_time();
3278         double elapsed_sec = os::elapsedTime() - start;
3279         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3280         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3281         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3282       }
3283 
3284       assert(pss->queue_is_empty(), "should be empty");
3285 
3286       if (log_is_enabled(Debug, gc, task, stats)) {
3287         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3288         size_t lab_waste;
3289         size_t lab_undo_waste;
3290         pss->waste(lab_waste, lab_undo_waste);
3291         _g1h->print_termination_stats(worker_id,
3292                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3293                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3294                                       term_sec * 1000.0,                          /* evac term time */
3295                                       evac_term_attempts,                         /* evac term attempts */
3296                                       lab_waste,                                  /* alloc buffer waste */
3297                                       lab_undo_waste                              /* undo waste */
3298                                       );
3299       }
3300 
3301       // Close the inner scope so that the ResourceMark and HandleMark
3302       // destructors are executed here and are included as part of the
3303       // "GC Worker Time".
3304     }
3305     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3306   }
3307 };
3308 
3309 void G1CollectedHeap::print_termination_stats_hdr() {
3310   log_debug(gc, task, stats)("GC Termination Stats");
3311   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3312   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3313   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3314 }
3315 
3316 void G1CollectedHeap::print_termination_stats(uint worker_id,
3317                                               double elapsed_ms,
3318                                               double strong_roots_ms,
3319                                               double term_ms,
3320                                               size_t term_attempts,
3321                                               size_t alloc_buffer_waste,
3322                                               size_t undo_waste) const {
3323   log_debug(gc, task, stats)
3324               ("%3d %9.2f %9.2f %6.2f "
3325                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3326                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3327                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3328                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3329                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3330                alloc_buffer_waste * HeapWordSize / K,
3331                undo_waste * HeapWordSize / K);
3332 }
3333 
3334 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3335 private:
3336   BoolObjectClosure* _is_alive;
3337   G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3338 
3339   int _initial_string_table_size;
3340   int _initial_symbol_table_size;
3341 
3342   bool  _process_strings;
3343   int _strings_processed;
3344   int _strings_removed;
3345 
3346   bool  _process_symbols;
3347   int _symbols_processed;
3348   int _symbols_removed;
3349 
3350   bool _process_string_dedup;
3351 
3352 public:
3353   G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3354     AbstractGangTask("String/Symbol Unlinking"),
3355     _is_alive(is_alive),
3356     _dedup_closure(is_alive, NULL, false),
3357     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3358     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3359     _process_string_dedup(process_string_dedup) {
3360 
3361     _initial_string_table_size = StringTable::the_table()->table_size();
3362     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3363     if (process_strings) {
3364       StringTable::clear_parallel_claimed_index();
3365     }
3366     if (process_symbols) {
3367       SymbolTable::clear_parallel_claimed_index();
3368     }
3369   }
3370 
3371   ~G1StringAndSymbolCleaningTask() {
3372     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3373               "claim value %d after unlink less than initial string table size %d",
3374               StringTable::parallel_claimed_index(), _initial_string_table_size);
3375     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3376               "claim value %d after unlink less than initial symbol table size %d",
3377               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3378 
3379     log_info(gc, stringtable)(
3380         "Cleaned string and symbol table, "
3381         "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3382         "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3383         strings_processed(), strings_removed(),
3384         symbols_processed(), symbols_removed());
3385   }
3386 
3387   void work(uint worker_id) {
3388     int strings_processed = 0;
3389     int strings_removed = 0;
3390     int symbols_processed = 0;
3391     int symbols_removed = 0;
3392     if (_process_strings) {
3393       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3394       Atomic::add(strings_processed, &_strings_processed);
3395       Atomic::add(strings_removed, &_strings_removed);
3396     }
3397     if (_process_symbols) {
3398       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3399       Atomic::add(symbols_processed, &_symbols_processed);
3400       Atomic::add(symbols_removed, &_symbols_removed);
3401     }
3402     if (_process_string_dedup) {
3403       G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3404     }
3405   }
3406 
3407   size_t strings_processed() const { return (size_t)_strings_processed; }
3408   size_t strings_removed()   const { return (size_t)_strings_removed; }
3409 
3410   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3411   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3412 };
3413 
3414 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3415 private:
3416   static Monitor* _lock;
3417 
3418   BoolObjectClosure* const _is_alive;
3419   const bool               _unloading_occurred;
3420   const uint               _num_workers;
3421 
3422   // Variables used to claim nmethods.
3423   CompiledMethod* _first_nmethod;
3424   CompiledMethod* volatile _claimed_nmethod;
3425 
3426   // The list of nmethods that need to be processed by the second pass.
3427   CompiledMethod* volatile _postponed_list;
3428   volatile uint            _num_entered_barrier;
3429 
3430  public:
3431   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3432       _is_alive(is_alive),
3433       _unloading_occurred(unloading_occurred),
3434       _num_workers(num_workers),
3435       _first_nmethod(NULL),
3436       _claimed_nmethod(NULL),
3437       _postponed_list(NULL),
3438       _num_entered_barrier(0)
3439   {
3440     CompiledMethod::increase_unloading_clock();
3441     // Get first alive nmethod
3442     CompiledMethodIterator iter = CompiledMethodIterator();
3443     if(iter.next_alive()) {
3444       _first_nmethod = iter.method();
3445     }
3446     _claimed_nmethod = _first_nmethod;
3447   }
3448 
3449   ~G1CodeCacheUnloadingTask() {
3450     CodeCache::verify_clean_inline_caches();
3451 
3452     CodeCache::set_needs_cache_clean(false);
3453     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3454 
3455     CodeCache::verify_icholder_relocations();
3456   }
3457 
3458  private:
3459   void add_to_postponed_list(CompiledMethod* nm) {
3460       CompiledMethod* old;
3461       do {
3462         old = _postponed_list;
3463         nm->set_unloading_next(old);
3464       } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3465   }
3466 
3467   void clean_nmethod(CompiledMethod* nm) {
3468     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3469 
3470     if (postponed) {
3471       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3472       add_to_postponed_list(nm);
3473     }
3474 
3475     // Mark that this thread has been cleaned/unloaded.
3476     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3477     nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3478   }
3479 
3480   void clean_nmethod_postponed(CompiledMethod* nm) {
3481     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3482   }
3483 
3484   static const int MaxClaimNmethods = 16;
3485 
3486   void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3487     CompiledMethod* first;
3488     CompiledMethodIterator last;
3489 
3490     do {
3491       *num_claimed_nmethods = 0;
3492 
3493       first = _claimed_nmethod;
3494       last = CompiledMethodIterator(first);
3495 
3496       if (first != NULL) {
3497 
3498         for (int i = 0; i < MaxClaimNmethods; i++) {
3499           if (!last.next_alive()) {
3500             break;
3501           }
3502           claimed_nmethods[i] = last.method();
3503           (*num_claimed_nmethods)++;
3504         }
3505       }
3506 
3507     } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3508   }
3509 
3510   CompiledMethod* claim_postponed_nmethod() {
3511     CompiledMethod* claim;
3512     CompiledMethod* next;
3513 
3514     do {
3515       claim = _postponed_list;
3516       if (claim == NULL) {
3517         return NULL;
3518       }
3519 
3520       next = claim->unloading_next();
3521 
3522     } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3523 
3524     return claim;
3525   }
3526 
3527  public:
3528   // Mark that we're done with the first pass of nmethod cleaning.
3529   void barrier_mark(uint worker_id) {
3530     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3531     _num_entered_barrier++;
3532     if (_num_entered_barrier == _num_workers) {
3533       ml.notify_all();
3534     }
3535   }
3536 
3537   // See if we have to wait for the other workers to
3538   // finish their first-pass nmethod cleaning work.
3539   void barrier_wait(uint worker_id) {
3540     if (_num_entered_barrier < _num_workers) {
3541       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3542       while (_num_entered_barrier < _num_workers) {
3543           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3544       }
3545     }
3546   }
3547 
3548   // Cleaning and unloading of nmethods. Some work has to be postponed
3549   // to the second pass, when we know which nmethods survive.
3550   void work_first_pass(uint worker_id) {
3551     // The first nmethods is claimed by the first worker.
3552     if (worker_id == 0 && _first_nmethod != NULL) {
3553       clean_nmethod(_first_nmethod);
3554       _first_nmethod = NULL;
3555     }
3556 
3557     int num_claimed_nmethods;
3558     CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3559 
3560     while (true) {
3561       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3562 
3563       if (num_claimed_nmethods == 0) {
3564         break;
3565       }
3566 
3567       for (int i = 0; i < num_claimed_nmethods; i++) {
3568         clean_nmethod(claimed_nmethods[i]);
3569       }
3570     }
3571   }
3572 
3573   void work_second_pass(uint worker_id) {
3574     CompiledMethod* nm;
3575     // Take care of postponed nmethods.
3576     while ((nm = claim_postponed_nmethod()) != NULL) {
3577       clean_nmethod_postponed(nm);
3578     }
3579   }
3580 };
3581 
3582 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3583 
3584 class G1KlassCleaningTask : public StackObj {
3585   BoolObjectClosure*                      _is_alive;
3586   volatile int                            _clean_klass_tree_claimed;
3587   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3588 
3589  public:
3590   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3591       _is_alive(is_alive),
3592       _clean_klass_tree_claimed(0),
3593       _klass_iterator() {
3594   }
3595 
3596  private:
3597   bool claim_clean_klass_tree_task() {
3598     if (_clean_klass_tree_claimed) {
3599       return false;
3600     }
3601 
3602     return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3603   }
3604 
3605   InstanceKlass* claim_next_klass() {
3606     Klass* klass;
3607     do {
3608       klass =_klass_iterator.next_klass();
3609     } while (klass != NULL && !klass->is_instance_klass());
3610 
3611     // this can be null so don't call InstanceKlass::cast
3612     return static_cast<InstanceKlass*>(klass);
3613   }
3614 
3615 public:
3616 
3617   void clean_klass(InstanceKlass* ik) {
3618     ik->clean_weak_instanceklass_links(_is_alive);
3619   }
3620 
3621   void work() {
3622     ResourceMark rm;
3623 
3624     // One worker will clean the subklass/sibling klass tree.
3625     if (claim_clean_klass_tree_task()) {
3626       Klass::clean_subklass_tree(_is_alive);
3627     }
3628 
3629     // All workers will help cleaning the classes,
3630     InstanceKlass* klass;
3631     while ((klass = claim_next_klass()) != NULL) {
3632       clean_klass(klass);
3633     }
3634   }
3635 };
3636 
3637 class G1ResolvedMethodCleaningTask : public StackObj {
3638   BoolObjectClosure* _is_alive;
3639   volatile int       _resolved_method_task_claimed;
3640 public:
3641   G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3642       _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3643 
3644   bool claim_resolved_method_task() {
3645     if (_resolved_method_task_claimed) {
3646       return false;
3647     }
3648     return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3649   }
3650 
3651   // These aren't big, one thread can do it all.
3652   void work() {
3653     if (claim_resolved_method_task()) {
3654       ResolvedMethodTable::unlink(_is_alive);
3655     }
3656   }
3657 };
3658 
3659 
3660 // To minimize the remark pause times, the tasks below are done in parallel.
3661 class G1ParallelCleaningTask : public AbstractGangTask {
3662 private:
3663   G1StringAndSymbolCleaningTask _string_symbol_task;
3664   G1CodeCacheUnloadingTask      _code_cache_task;
3665   G1KlassCleaningTask           _klass_cleaning_task;
3666   G1ResolvedMethodCleaningTask  _resolved_method_cleaning_task;
3667 
3668 public:
3669   // The constructor is run in the VMThread.
3670   G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3671       AbstractGangTask("Parallel Cleaning"),
3672       _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3673       _code_cache_task(num_workers, is_alive, unloading_occurred),
3674       _klass_cleaning_task(is_alive),
3675       _resolved_method_cleaning_task(is_alive) {
3676   }
3677 
3678   // The parallel work done by all worker threads.
3679   void work(uint worker_id) {
3680     // Do first pass of code cache cleaning.
3681     _code_cache_task.work_first_pass(worker_id);
3682 
3683     // Let the threads mark that the first pass is done.
3684     _code_cache_task.barrier_mark(worker_id);
3685 
3686     // Clean the Strings and Symbols.
3687     _string_symbol_task.work(worker_id);
3688 
3689     // Clean unreferenced things in the ResolvedMethodTable
3690     _resolved_method_cleaning_task.work();
3691 
3692     // Wait for all workers to finish the first code cache cleaning pass.
3693     _code_cache_task.barrier_wait(worker_id);
3694 
3695     // Do the second code cache cleaning work, which realize on
3696     // the liveness information gathered during the first pass.
3697     _code_cache_task.work_second_pass(worker_id);
3698 
3699     // Clean all klasses that were not unloaded.
3700     _klass_cleaning_task.work();
3701   }
3702 };
3703 
3704 
3705 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3706                                         bool class_unloading_occurred) {
3707   uint n_workers = workers()->active_workers();
3708 
3709   G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3710   workers()->run_task(&g1_unlink_task);
3711 }
3712 
3713 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3714                                        bool process_strings,
3715                                        bool process_symbols,
3716                                        bool process_string_dedup) {
3717   if (!process_strings && !process_symbols && !process_string_dedup) {
3718     // Nothing to clean.
3719     return;
3720   }
3721 
3722   G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3723   workers()->run_task(&g1_unlink_task);
3724 
3725 }
3726 
3727 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3728  private:
3729   DirtyCardQueueSet* _queue;
3730   G1CollectedHeap* _g1h;
3731  public:
3732   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3733     _queue(queue), _g1h(g1h) { }
3734 
3735   virtual void work(uint worker_id) {
3736     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3737     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3738 
3739     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3740     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3741 
3742     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3743   }
3744 };
3745 
3746 void G1CollectedHeap::redirty_logged_cards() {
3747   double redirty_logged_cards_start = os::elapsedTime();
3748 
3749   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3750   dirty_card_queue_set().reset_for_par_iteration();
3751   workers()->run_task(&redirty_task);
3752 
3753   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3754   dcq.merge_bufferlists(&dirty_card_queue_set());
3755   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3756 
3757   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3758 }
3759 
3760 // Weak Reference Processing support
3761 
3762 // An always "is_alive" closure that is used to preserve referents.
3763 // If the object is non-null then it's alive.  Used in the preservation
3764 // of referent objects that are pointed to by reference objects
3765 // discovered by the CM ref processor.
3766 class G1AlwaysAliveClosure: public BoolObjectClosure {
3767   G1CollectedHeap* _g1;
3768 public:
3769   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3770   bool do_object_b(oop p) {
3771     if (p != NULL) {
3772       return true;
3773     }
3774     return false;
3775   }
3776 };
3777 
3778 bool G1STWIsAliveClosure::do_object_b(oop p) {
3779   // An object is reachable if it is outside the collection set,
3780   // or is inside and copied.
3781   return !_g1->is_in_cset(p) || p->is_forwarded();
3782 }
3783 
3784 // Non Copying Keep Alive closure
3785 class G1KeepAliveClosure: public OopClosure {
3786   G1CollectedHeap* _g1;
3787 public:
3788   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3789   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3790   void do_oop(oop* p) {
3791     oop obj = *p;
3792     assert(obj != NULL, "the caller should have filtered out NULL values");
3793 
3794     const InCSetState cset_state = _g1->in_cset_state(obj);
3795     if (!cset_state.is_in_cset_or_humongous()) {
3796       return;
3797     }
3798     if (cset_state.is_in_cset()) {
3799       assert( obj->is_forwarded(), "invariant" );
3800       *p = obj->forwardee();
3801     } else {
3802       assert(!obj->is_forwarded(), "invariant" );
3803       assert(cset_state.is_humongous(),
3804              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3805       _g1->set_humongous_is_live(obj);
3806     }
3807   }
3808 };
3809 
3810 // Copying Keep Alive closure - can be called from both
3811 // serial and parallel code as long as different worker
3812 // threads utilize different G1ParScanThreadState instances
3813 // and different queues.
3814 
3815 class G1CopyingKeepAliveClosure: public OopClosure {
3816   G1CollectedHeap*         _g1h;
3817   OopClosure*              _copy_non_heap_obj_cl;
3818   G1ParScanThreadState*    _par_scan_state;
3819 
3820 public:
3821   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3822                             OopClosure* non_heap_obj_cl,
3823                             G1ParScanThreadState* pss):
3824     _g1h(g1h),
3825     _copy_non_heap_obj_cl(non_heap_obj_cl),
3826     _par_scan_state(pss)
3827   {}
3828 
3829   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3830   virtual void do_oop(      oop* p) { do_oop_work(p); }
3831 
3832   template <class T> void do_oop_work(T* p) {
3833     oop obj = oopDesc::load_decode_heap_oop(p);
3834 
3835     if (_g1h->is_in_cset_or_humongous(obj)) {
3836       // If the referent object has been forwarded (either copied
3837       // to a new location or to itself in the event of an
3838       // evacuation failure) then we need to update the reference
3839       // field and, if both reference and referent are in the G1
3840       // heap, update the RSet for the referent.
3841       //
3842       // If the referent has not been forwarded then we have to keep
3843       // it alive by policy. Therefore we have copy the referent.
3844       //
3845       // If the reference field is in the G1 heap then we can push
3846       // on the PSS queue. When the queue is drained (after each
3847       // phase of reference processing) the object and it's followers
3848       // will be copied, the reference field set to point to the
3849       // new location, and the RSet updated. Otherwise we need to
3850       // use the the non-heap or metadata closures directly to copy
3851       // the referent object and update the pointer, while avoiding
3852       // updating the RSet.
3853 
3854       if (_g1h->is_in_g1_reserved(p)) {
3855         _par_scan_state->push_on_queue(p);
3856       } else {
3857         assert(!Metaspace::contains((const void*)p),
3858                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3859         _copy_non_heap_obj_cl->do_oop(p);
3860       }
3861     }
3862   }
3863 };
3864 
3865 // Serial drain queue closure. Called as the 'complete_gc'
3866 // closure for each discovered list in some of the
3867 // reference processing phases.
3868 
3869 class G1STWDrainQueueClosure: public VoidClosure {
3870 protected:
3871   G1CollectedHeap* _g1h;
3872   G1ParScanThreadState* _par_scan_state;
3873 
3874   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3875 
3876 public:
3877   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3878     _g1h(g1h),
3879     _par_scan_state(pss)
3880   { }
3881 
3882   void do_void() {
3883     G1ParScanThreadState* const pss = par_scan_state();
3884     pss->trim_queue();
3885   }
3886 };
3887 
3888 // Parallel Reference Processing closures
3889 
3890 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3891 // processing during G1 evacuation pauses.
3892 
3893 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3894 private:
3895   G1CollectedHeap*          _g1h;
3896   G1ParScanThreadStateSet*  _pss;
3897   RefToScanQueueSet*        _queues;
3898   WorkGang*                 _workers;
3899   uint                      _active_workers;
3900 
3901 public:
3902   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3903                            G1ParScanThreadStateSet* per_thread_states,
3904                            WorkGang* workers,
3905                            RefToScanQueueSet *task_queues,
3906                            uint n_workers) :
3907     _g1h(g1h),
3908     _pss(per_thread_states),
3909     _queues(task_queues),
3910     _workers(workers),
3911     _active_workers(n_workers)
3912   {
3913     g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3914   }
3915 
3916   // Executes the given task using concurrent marking worker threads.
3917   virtual void execute(ProcessTask& task);
3918   virtual void execute(EnqueueTask& task);
3919 };
3920 
3921 // Gang task for possibly parallel reference processing
3922 
3923 class G1STWRefProcTaskProxy: public AbstractGangTask {
3924   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3925   ProcessTask&     _proc_task;
3926   G1CollectedHeap* _g1h;
3927   G1ParScanThreadStateSet* _pss;
3928   RefToScanQueueSet* _task_queues;
3929   ParallelTaskTerminator* _terminator;
3930 
3931 public:
3932   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3933                         G1CollectedHeap* g1h,
3934                         G1ParScanThreadStateSet* per_thread_states,
3935                         RefToScanQueueSet *task_queues,
3936                         ParallelTaskTerminator* terminator) :
3937     AbstractGangTask("Process reference objects in parallel"),
3938     _proc_task(proc_task),
3939     _g1h(g1h),
3940     _pss(per_thread_states),
3941     _task_queues(task_queues),
3942     _terminator(terminator)
3943   {}
3944 
3945   virtual void work(uint worker_id) {
3946     // The reference processing task executed by a single worker.
3947     ResourceMark rm;
3948     HandleMark   hm;
3949 
3950     G1STWIsAliveClosure is_alive(_g1h);
3951 
3952     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
3953     pss->set_ref_processor(NULL);
3954 
3955     // Keep alive closure.
3956     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3957 
3958     // Complete GC closure
3959     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3960 
3961     // Call the reference processing task's work routine.
3962     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3963 
3964     // Note we cannot assert that the refs array is empty here as not all
3965     // of the processing tasks (specifically phase2 - pp2_work) execute
3966     // the complete_gc closure (which ordinarily would drain the queue) so
3967     // the queue may not be empty.
3968   }
3969 };
3970 
3971 // Driver routine for parallel reference processing.
3972 // Creates an instance of the ref processing gang
3973 // task and has the worker threads execute it.
3974 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3975   assert(_workers != NULL, "Need parallel worker threads.");
3976 
3977   ParallelTaskTerminator terminator(_active_workers, _queues);
3978   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3979 
3980   _workers->run_task(&proc_task_proxy);
3981 }
3982 
3983 // Gang task for parallel reference enqueueing.
3984 
3985 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
3986   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
3987   EnqueueTask& _enq_task;
3988 
3989 public:
3990   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
3991     AbstractGangTask("Enqueue reference objects in parallel"),
3992     _enq_task(enq_task)
3993   { }
3994 
3995   virtual void work(uint worker_id) {
3996     _enq_task.work(worker_id);
3997   }
3998 };
3999 
4000 // Driver routine for parallel reference enqueueing.
4001 // Creates an instance of the ref enqueueing gang
4002 // task and has the worker threads execute it.
4003 
4004 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4005   assert(_workers != NULL, "Need parallel worker threads.");
4006 
4007   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4008 
4009   _workers->run_task(&enq_task_proxy);
4010 }
4011 
4012 // End of weak reference support closures
4013 
4014 // Abstract task used to preserve (i.e. copy) any referent objects
4015 // that are in the collection set and are pointed to by reference
4016 // objects discovered by the CM ref processor.
4017 
4018 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4019 protected:
4020   G1CollectedHeap*         _g1h;
4021   G1ParScanThreadStateSet* _pss;
4022   RefToScanQueueSet*       _queues;
4023   ParallelTaskTerminator   _terminator;
4024   uint                     _n_workers;
4025 
4026 public:
4027   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4028     AbstractGangTask("ParPreserveCMReferents"),
4029     _g1h(g1h),
4030     _pss(per_thread_states),
4031     _queues(task_queues),
4032     _terminator(workers, _queues),
4033     _n_workers(workers)
4034   {
4035     g1h->ref_processor_cm()->set_active_mt_degree(workers);
4036   }
4037 
4038   void work(uint worker_id) {
4039     G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4040 
4041     ResourceMark rm;
4042     HandleMark   hm;
4043 
4044     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4045     pss->set_ref_processor(NULL);
4046     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4047 
4048     // Is alive closure
4049     G1AlwaysAliveClosure always_alive(_g1h);
4050 
4051     // Copying keep alive closure. Applied to referent objects that need
4052     // to be copied.
4053     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4054 
4055     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4056 
4057     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4058     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4059 
4060     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4061     // So this must be true - but assert just in case someone decides to
4062     // change the worker ids.
4063     assert(worker_id < limit, "sanity");
4064     assert(!rp->discovery_is_atomic(), "check this code");
4065 
4066     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4067     for (uint idx = worker_id; idx < limit; idx += stride) {
4068       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4069 
4070       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4071       while (iter.has_next()) {
4072         // Since discovery is not atomic for the CM ref processor, we
4073         // can see some null referent objects.
4074         iter.load_ptrs(DEBUG_ONLY(true));
4075         oop ref = iter.obj();
4076 
4077         // This will filter nulls.
4078         if (iter.is_referent_alive()) {
4079           iter.make_referent_alive();
4080         }
4081         iter.move_to_next();
4082       }
4083     }
4084 
4085     // Drain the queue - which may cause stealing
4086     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4087     drain_queue.do_void();
4088     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4089     assert(pss->queue_is_empty(), "should be");
4090   }
4091 };
4092 
4093 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4094   // Any reference objects, in the collection set, that were 'discovered'
4095   // by the CM ref processor should have already been copied (either by
4096   // applying the external root copy closure to the discovered lists, or
4097   // by following an RSet entry).
4098   //
4099   // But some of the referents, that are in the collection set, that these
4100   // reference objects point to may not have been copied: the STW ref
4101   // processor would have seen that the reference object had already
4102   // been 'discovered' and would have skipped discovering the reference,
4103   // but would not have treated the reference object as a regular oop.
4104   // As a result the copy closure would not have been applied to the
4105   // referent object.
4106   //
4107   // We need to explicitly copy these referent objects - the references
4108   // will be processed at the end of remarking.
4109   //
4110   // We also need to do this copying before we process the reference
4111   // objects discovered by the STW ref processor in case one of these
4112   // referents points to another object which is also referenced by an
4113   // object discovered by the STW ref processor.
4114   double preserve_cm_referents_time = 0.0;
4115 
4116   // To avoid spawning task when there is no work to do, check that
4117   // a concurrent cycle is active and that some references have been
4118   // discovered.
4119   if (concurrent_mark()->cm_thread()->during_cycle() &&
4120       ref_processor_cm()->has_discovered_references()) {
4121     double preserve_cm_referents_start = os::elapsedTime();
4122     uint no_of_gc_workers = workers()->active_workers();
4123     G1ParPreserveCMReferentsTask keep_cm_referents(this,
4124                                                    per_thread_states,
4125                                                    no_of_gc_workers,
4126                                                    _task_queues);
4127     workers()->run_task(&keep_cm_referents);
4128     preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4129   }
4130 
4131   g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4132 }
4133 
4134 // Weak Reference processing during an evacuation pause (part 1).
4135 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4136   double ref_proc_start = os::elapsedTime();
4137 
4138   ReferenceProcessor* rp = _ref_processor_stw;
4139   assert(rp->discovery_enabled(), "should have been enabled");
4140 
4141   // Closure to test whether a referent is alive.
4142   G1STWIsAliveClosure is_alive(this);
4143 
4144   // Even when parallel reference processing is enabled, the processing
4145   // of JNI refs is serial and performed serially by the current thread
4146   // rather than by a worker. The following PSS will be used for processing
4147   // JNI refs.
4148 
4149   // Use only a single queue for this PSS.
4150   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4151   pss->set_ref_processor(NULL);
4152   assert(pss->queue_is_empty(), "pre-condition");
4153 
4154   // Keep alive closure.
4155   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4156 
4157   // Serial Complete GC closure
4158   G1STWDrainQueueClosure drain_queue(this, pss);
4159 
4160   // Setup the soft refs policy...
4161   rp->setup_policy(false);
4162 
4163   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4164 
4165   ReferenceProcessorStats stats;
4166   if (!rp->processing_is_mt()) {
4167     // Serial reference processing...
4168     stats = rp->process_discovered_references(&is_alive,
4169                                               &keep_alive,
4170                                               &drain_queue,
4171                                               NULL,
4172                                               pt);
4173   } else {
4174     uint no_of_gc_workers = workers()->active_workers();
4175 
4176     // Parallel reference processing
4177     assert(no_of_gc_workers <= rp->max_num_q(),
4178            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4179            no_of_gc_workers,  rp->max_num_q());
4180 
4181     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4182     stats = rp->process_discovered_references(&is_alive,
4183                                               &keep_alive,
4184                                               &drain_queue,
4185                                               &par_task_executor,
4186                                               pt);
4187   }
4188 
4189   _gc_tracer_stw->report_gc_reference_stats(stats);
4190 
4191   // We have completed copying any necessary live referent objects.
4192   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4193 
4194   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4195   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4196 }
4197 
4198 // Weak Reference processing during an evacuation pause (part 2).
4199 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4200   double ref_enq_start = os::elapsedTime();
4201 
4202   ReferenceProcessor* rp = _ref_processor_stw;
4203   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4204 
4205   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4206 
4207   // Now enqueue any remaining on the discovered lists on to
4208   // the pending list.
4209   if (!rp->processing_is_mt()) {
4210     // Serial reference processing...
4211     rp->enqueue_discovered_references(NULL, pt);
4212   } else {
4213     // Parallel reference enqueueing
4214 
4215     uint n_workers = workers()->active_workers();
4216 
4217     assert(n_workers <= rp->max_num_q(),
4218            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4219            n_workers,  rp->max_num_q());
4220 
4221     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4222     rp->enqueue_discovered_references(&par_task_executor, pt);
4223   }
4224 
4225   rp->verify_no_references_recorded();
4226   assert(!rp->discovery_enabled(), "should have been disabled");
4227 
4228   // If during an initial mark pause we install a pending list head which is not otherwise reachable
4229   // ensure that it is marked in the bitmap for concurrent marking to discover.
4230   if (collector_state()->during_initial_mark_pause()) {
4231     oop pll_head = Universe::reference_pending_list();
4232     if (pll_head != NULL) {
4233       _cm->mark_in_next_bitmap(pll_head);
4234     }
4235   }
4236 
4237   // FIXME
4238   // CM's reference processing also cleans up the string and symbol tables.
4239   // Should we do that here also? We could, but it is a serial operation
4240   // and could significantly increase the pause time.
4241 
4242   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4243   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4244 }
4245 
4246 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4247   double merge_pss_time_start = os::elapsedTime();
4248   per_thread_states->flush();
4249   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4250 }
4251 
4252 void G1CollectedHeap::pre_evacuate_collection_set() {
4253   _expand_heap_after_alloc_failure = true;
4254   _evacuation_failed = false;
4255 
4256   // Disable the hot card cache.
4257   _hot_card_cache->reset_hot_cache_claimed_index();
4258   _hot_card_cache->set_use_cache(false);
4259 
4260   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4261   _preserved_marks_set.assert_empty();
4262 
4263   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4264 
4265   // InitialMark needs claim bits to keep track of the marked-through CLDs.
4266   if (collector_state()->during_initial_mark_pause()) {
4267     double start_clear_claimed_marks = os::elapsedTime();
4268 
4269     ClassLoaderDataGraph::clear_claimed_marks();
4270 
4271     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4272     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4273   }
4274 }
4275 
4276 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4277   // Should G1EvacuationFailureALot be in effect for this GC?
4278   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4279 
4280   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4281 
4282   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4283 
4284   double start_par_time_sec = os::elapsedTime();
4285   double end_par_time_sec;
4286 
4287   {
4288     const uint n_workers = workers()->active_workers();
4289     G1RootProcessor root_processor(this, n_workers);
4290     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4291 
4292     print_termination_stats_hdr();
4293 
4294     workers()->run_task(&g1_par_task);
4295     end_par_time_sec = os::elapsedTime();
4296 
4297     // Closing the inner scope will execute the destructor
4298     // for the G1RootProcessor object. We record the current
4299     // elapsed time before closing the scope so that time
4300     // taken for the destructor is NOT included in the
4301     // reported parallel time.
4302   }
4303 
4304   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4305   phase_times->record_par_time(par_time_ms);
4306 
4307   double code_root_fixup_time_ms =
4308         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4309   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4310 }
4311 
4312 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4313   // Process any discovered reference objects - we have
4314   // to do this _before_ we retire the GC alloc regions
4315   // as we may have to copy some 'reachable' referent
4316   // objects (and their reachable sub-graphs) that were
4317   // not copied during the pause.
4318   if (g1_policy()->should_process_references()) {
4319     preserve_cm_referents(per_thread_states);
4320     process_discovered_references(per_thread_states);
4321   } else {
4322     ref_processor_stw()->verify_no_references_recorded();
4323   }
4324 
4325   G1STWIsAliveClosure is_alive(this);
4326   G1KeepAliveClosure keep_alive(this);
4327 
4328   {
4329     double start = os::elapsedTime();
4330 
4331     WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4332 
4333     double time_ms = (os::elapsedTime() - start) * 1000.0;
4334     g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4335   }
4336 
4337   if (G1StringDedup::is_enabled()) {
4338     double fixup_start = os::elapsedTime();
4339 
4340     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4341 
4342     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4343     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4344   }
4345 
4346   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4347 
4348   if (evacuation_failed()) {
4349     restore_after_evac_failure();
4350 
4351     // Reset the G1EvacuationFailureALot counters and flags
4352     // Note: the values are reset only when an actual
4353     // evacuation failure occurs.
4354     NOT_PRODUCT(reset_evacuation_should_fail();)
4355   }
4356 
4357   _preserved_marks_set.assert_empty();
4358 
4359   // Enqueue any remaining references remaining on the STW
4360   // reference processor's discovered lists. We need to do
4361   // this after the card table is cleaned (and verified) as
4362   // the act of enqueueing entries on to the pending list
4363   // will log these updates (and dirty their associated
4364   // cards). We need these updates logged to update any
4365   // RSets.
4366   if (g1_policy()->should_process_references()) {
4367     enqueue_discovered_references(per_thread_states);
4368   } else {
4369     g1_policy()->phase_times()->record_ref_enq_time(0);
4370   }
4371 
4372   _allocator->release_gc_alloc_regions(evacuation_info);
4373 
4374   merge_per_thread_state_info(per_thread_states);
4375 
4376   // Reset and re-enable the hot card cache.
4377   // Note the counts for the cards in the regions in the
4378   // collection set are reset when the collection set is freed.
4379   _hot_card_cache->reset_hot_cache();
4380   _hot_card_cache->set_use_cache(true);
4381 
4382   purge_code_root_memory();
4383 
4384   redirty_logged_cards();
4385 #if COMPILER2_OR_JVMCI
4386   double start = os::elapsedTime();
4387   DerivedPointerTable::update_pointers();
4388   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4389 #endif
4390   g1_policy()->print_age_table();
4391 }
4392 
4393 void G1CollectedHeap::record_obj_copy_mem_stats() {
4394   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4395 
4396   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4397                                                create_g1_evac_summary(&_old_evac_stats));
4398 }
4399 
4400 void G1CollectedHeap::free_region(HeapRegion* hr,
4401                                   FreeRegionList* free_list,
4402                                   bool skip_remset,
4403                                   bool skip_hot_card_cache,
4404                                   bool locked) {
4405   assert(!hr->is_free(), "the region should not be free");
4406   assert(!hr->is_empty(), "the region should not be empty");
4407   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4408   assert(free_list != NULL, "pre-condition");
4409 
4410   if (G1VerifyBitmaps) {
4411     MemRegion mr(hr->bottom(), hr->end());
4412     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4413   }
4414 
4415   // Clear the card counts for this region.
4416   // Note: we only need to do this if the region is not young
4417   // (since we don't refine cards in young regions).
4418   if (!skip_hot_card_cache && !hr->is_young()) {
4419     _hot_card_cache->reset_card_counts(hr);
4420   }
4421   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4422   free_list->add_ordered(hr);
4423 }
4424 
4425 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4426                                             FreeRegionList* free_list,
4427                                             bool skip_remset) {
4428   assert(hr->is_humongous(), "this is only for humongous regions");
4429   assert(free_list != NULL, "pre-condition");
4430   hr->clear_humongous();
4431   free_region(hr, free_list, skip_remset);
4432 }
4433 
4434 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4435                                            const uint humongous_regions_removed) {
4436   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4437     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4438     _old_set.bulk_remove(old_regions_removed);
4439     _humongous_set.bulk_remove(humongous_regions_removed);
4440   }
4441 
4442 }
4443 
4444 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4445   assert(list != NULL, "list can't be null");
4446   if (!list->is_empty()) {
4447     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4448     _hrm.insert_list_into_free_list(list);
4449   }
4450 }
4451 
4452 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4453   decrease_used(bytes);
4454 }
4455 
4456 class G1ParScrubRemSetTask: public AbstractGangTask {
4457 protected:
4458   G1RemSet* _g1rs;
4459   HeapRegionClaimer _hrclaimer;
4460 
4461 public:
4462   G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4463     AbstractGangTask("G1 ScrubRS"),
4464     _g1rs(g1_rs),
4465     _hrclaimer(num_workers) {
4466   }
4467 
4468   void work(uint worker_id) {
4469     _g1rs->scrub(worker_id, &_hrclaimer);
4470   }
4471 };
4472 
4473 void G1CollectedHeap::scrub_rem_set() {
4474   uint num_workers = workers()->active_workers();
4475   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4476   workers()->run_task(&g1_par_scrub_rs_task);
4477 }
4478 
4479 class G1FreeCollectionSetTask : public AbstractGangTask {
4480 private:
4481 
4482   // Closure applied to all regions in the collection set to do work that needs to
4483   // be done serially in a single thread.
4484   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4485   private:
4486     EvacuationInfo* _evacuation_info;
4487     const size_t* _surviving_young_words;
4488 
4489     // Bytes used in successfully evacuated regions before the evacuation.
4490     size_t _before_used_bytes;
4491     // Bytes used in unsucessfully evacuated regions before the evacuation
4492     size_t _after_used_bytes;
4493 
4494     size_t _bytes_allocated_in_old_since_last_gc;
4495 
4496     size_t _failure_used_words;
4497     size_t _failure_waste_words;
4498 
4499     FreeRegionList _local_free_list;
4500   public:
4501     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4502       HeapRegionClosure(),
4503       _evacuation_info(evacuation_info),
4504       _surviving_young_words(surviving_young_words),
4505       _before_used_bytes(0),
4506       _after_used_bytes(0),
4507       _bytes_allocated_in_old_since_last_gc(0),
4508       _failure_used_words(0),
4509       _failure_waste_words(0),
4510       _local_free_list("Local Region List for CSet Freeing") {
4511     }
4512 
4513     virtual bool do_heap_region(HeapRegion* r) {
4514       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4515 
4516       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4517       g1h->clear_in_cset(r);
4518 
4519       if (r->is_young()) {
4520         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4521                "Young index %d is wrong for region %u of type %s with %u young regions",
4522                r->young_index_in_cset(),
4523                r->hrm_index(),
4524                r->get_type_str(),
4525                g1h->collection_set()->young_region_length());
4526         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4527         r->record_surv_words_in_group(words_survived);
4528       }
4529 
4530       if (!r->evacuation_failed()) {
4531         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4532         _before_used_bytes += r->used();
4533         g1h->free_region(r,
4534                          &_local_free_list,
4535                          true, /* skip_remset */
4536                          true, /* skip_hot_card_cache */
4537                          true  /* locked */);
4538       } else {
4539         r->uninstall_surv_rate_group();
4540         r->set_young_index_in_cset(-1);
4541         r->set_evacuation_failed(false);
4542         // When moving a young gen region to old gen, we "allocate" that whole region
4543         // there. This is in addition to any already evacuated objects. Notify the
4544         // policy about that.
4545         // Old gen regions do not cause an additional allocation: both the objects
4546         // still in the region and the ones already moved are accounted for elsewhere.
4547         if (r->is_young()) {
4548           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4549         }
4550         // The region is now considered to be old.
4551         r->set_old();
4552         // Do some allocation statistics accounting. Regions that failed evacuation
4553         // are always made old, so there is no need to update anything in the young
4554         // gen statistics, but we need to update old gen statistics.
4555         size_t used_words = r->marked_bytes() / HeapWordSize;
4556 
4557         _failure_used_words += used_words;
4558         _failure_waste_words += HeapRegion::GrainWords - used_words;
4559 
4560         g1h->old_set_add(r);
4561         _after_used_bytes += r->used();
4562       }
4563       return false;
4564     }
4565 
4566     void complete_work() {
4567       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4568 
4569       _evacuation_info->set_regions_freed(_local_free_list.length());
4570       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4571 
4572       g1h->prepend_to_freelist(&_local_free_list);
4573       g1h->decrement_summary_bytes(_before_used_bytes);
4574 
4575       G1Policy* policy = g1h->g1_policy();
4576       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4577 
4578       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4579     }
4580   };
4581 
4582   G1CollectionSet* _collection_set;
4583   G1SerialFreeCollectionSetClosure _cl;
4584   const size_t* _surviving_young_words;
4585 
4586   size_t _rs_lengths;
4587 
4588   volatile jint _serial_work_claim;
4589 
4590   struct WorkItem {
4591     uint region_idx;
4592     bool is_young;
4593     bool evacuation_failed;
4594 
4595     WorkItem(HeapRegion* r) {
4596       region_idx = r->hrm_index();
4597       is_young = r->is_young();
4598       evacuation_failed = r->evacuation_failed();
4599     }
4600   };
4601 
4602   volatile size_t _parallel_work_claim;
4603   size_t _num_work_items;
4604   WorkItem* _work_items;
4605 
4606   void do_serial_work() {
4607     // Need to grab the lock to be allowed to modify the old region list.
4608     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4609     _collection_set->iterate(&_cl);
4610   }
4611 
4612   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4613     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4614 
4615     HeapRegion* r = g1h->region_at(region_idx);
4616     assert(!g1h->is_on_master_free_list(r), "sanity");
4617 
4618     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4619 
4620     if (!is_young) {
4621       g1h->_hot_card_cache->reset_card_counts(r);
4622     }
4623 
4624     if (!evacuation_failed) {
4625       r->rem_set()->clear_locked();
4626     }
4627   }
4628 
4629   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4630   private:
4631     size_t _cur_idx;
4632     WorkItem* _work_items;
4633   public:
4634     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4635 
4636     virtual bool do_heap_region(HeapRegion* r) {
4637       _work_items[_cur_idx++] = WorkItem(r);
4638       return false;
4639     }
4640   };
4641 
4642   void prepare_work() {
4643     G1PrepareFreeCollectionSetClosure cl(_work_items);
4644     _collection_set->iterate(&cl);
4645   }
4646 
4647   void complete_work() {
4648     _cl.complete_work();
4649 
4650     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4651     policy->record_max_rs_lengths(_rs_lengths);
4652     policy->cset_regions_freed();
4653   }
4654 public:
4655   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4656     AbstractGangTask("G1 Free Collection Set"),
4657     _cl(evacuation_info, surviving_young_words),
4658     _collection_set(collection_set),
4659     _surviving_young_words(surviving_young_words),
4660     _serial_work_claim(0),
4661     _rs_lengths(0),
4662     _parallel_work_claim(0),
4663     _num_work_items(collection_set->region_length()),
4664     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4665     prepare_work();
4666   }
4667 
4668   ~G1FreeCollectionSetTask() {
4669     complete_work();
4670     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4671   }
4672 
4673   // Chunk size for work distribution. The chosen value has been determined experimentally
4674   // to be a good tradeoff between overhead and achievable parallelism.
4675   static uint chunk_size() { return 32; }
4676 
4677   virtual void work(uint worker_id) {
4678     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4679 
4680     // Claim serial work.
4681     if (_serial_work_claim == 0) {
4682       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4683       if (value == 0) {
4684         double serial_time = os::elapsedTime();
4685         do_serial_work();
4686         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4687       }
4688     }
4689 
4690     // Start parallel work.
4691     double young_time = 0.0;
4692     bool has_young_time = false;
4693     double non_young_time = 0.0;
4694     bool has_non_young_time = false;
4695 
4696     while (true) {
4697       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4698       size_t cur = end - chunk_size();
4699 
4700       if (cur >= _num_work_items) {
4701         break;
4702       }
4703 
4704       double start_time = os::elapsedTime();
4705 
4706       end = MIN2(end, _num_work_items);
4707 
4708       for (; cur < end; cur++) {
4709         bool is_young = _work_items[cur].is_young;
4710 
4711         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4712 
4713         double end_time = os::elapsedTime();
4714         double time_taken = end_time - start_time;
4715         if (is_young) {
4716           young_time += time_taken;
4717           has_young_time = true;
4718         } else {
4719           non_young_time += time_taken;
4720           has_non_young_time = true;
4721         }
4722         start_time = end_time;
4723       }
4724     }
4725 
4726     if (has_young_time) {
4727       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4728     }
4729     if (has_non_young_time) {
4730       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4731     }
4732   }
4733 };
4734 
4735 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4736   _eden.clear();
4737 
4738   double free_cset_start_time = os::elapsedTime();
4739 
4740   {
4741     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4742     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4743 
4744     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4745 
4746     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4747                         cl.name(),
4748                         num_workers,
4749                         _collection_set.region_length());
4750     workers()->run_task(&cl, num_workers);
4751   }
4752   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4753 
4754   collection_set->clear();
4755 }
4756 
4757 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4758  private:
4759   FreeRegionList* _free_region_list;
4760   HeapRegionSet* _proxy_set;
4761   uint _humongous_objects_reclaimed;
4762   uint _humongous_regions_reclaimed;
4763   size_t _freed_bytes;
4764  public:
4765 
4766   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4767     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4768   }
4769 
4770   virtual bool do_heap_region(HeapRegion* r) {
4771     if (!r->is_starts_humongous()) {
4772       return false;
4773     }
4774 
4775     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4776 
4777     oop obj = (oop)r->bottom();
4778     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4779 
4780     // The following checks whether the humongous object is live are sufficient.
4781     // The main additional check (in addition to having a reference from the roots
4782     // or the young gen) is whether the humongous object has a remembered set entry.
4783     //
4784     // A humongous object cannot be live if there is no remembered set for it
4785     // because:
4786     // - there can be no references from within humongous starts regions referencing
4787     // the object because we never allocate other objects into them.
4788     // (I.e. there are no intra-region references that may be missed by the
4789     // remembered set)
4790     // - as soon there is a remembered set entry to the humongous starts region
4791     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4792     // until the end of a concurrent mark.
4793     //
4794     // It is not required to check whether the object has been found dead by marking
4795     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4796     // all objects allocated during that time are considered live.
4797     // SATB marking is even more conservative than the remembered set.
4798     // So if at this point in the collection there is no remembered set entry,
4799     // nobody has a reference to it.
4800     // At the start of collection we flush all refinement logs, and remembered sets
4801     // are completely up-to-date wrt to references to the humongous object.
4802     //
4803     // Other implementation considerations:
4804     // - never consider object arrays at this time because they would pose
4805     // considerable effort for cleaning up the the remembered sets. This is
4806     // required because stale remembered sets might reference locations that
4807     // are currently allocated into.
4808     uint region_idx = r->hrm_index();
4809     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4810         !r->rem_set()->is_empty()) {
4811       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",
4812                                region_idx,
4813                                (size_t)obj->size() * HeapWordSize,
4814                                p2i(r->bottom()),
4815                                r->rem_set()->occupied(),
4816                                r->rem_set()->strong_code_roots_list_length(),
4817                                next_bitmap->is_marked(r->bottom()),
4818                                g1h->is_humongous_reclaim_candidate(region_idx),
4819                                obj->is_typeArray()
4820                               );
4821       return false;
4822     }
4823 
4824     guarantee(obj->is_typeArray(),
4825               "Only eagerly reclaiming type arrays is supported, but the object "
4826               PTR_FORMAT " is not.", p2i(r->bottom()));
4827 
4828     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",
4829                              region_idx,
4830                              (size_t)obj->size() * HeapWordSize,
4831                              p2i(r->bottom()),
4832                              r->rem_set()->occupied(),
4833                              r->rem_set()->strong_code_roots_list_length(),
4834                              next_bitmap->is_marked(r->bottom()),
4835                              g1h->is_humongous_reclaim_candidate(region_idx),
4836                              obj->is_typeArray()
4837                             );
4838 
4839     // Need to clear mark bit of the humongous object if already set.
4840     if (next_bitmap->is_marked(r->bottom())) {
4841       next_bitmap->clear(r->bottom());
4842     }
4843     _humongous_objects_reclaimed++;
4844     do {
4845       HeapRegion* next = g1h->next_region_in_humongous(r);
4846       _freed_bytes += r->used();
4847       r->set_containing_set(NULL);
4848       _humongous_regions_reclaimed++;
4849       g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4850       r = next;
4851     } while (r != NULL);
4852 
4853     return false;
4854   }
4855 
4856   uint humongous_objects_reclaimed() {
4857     return _humongous_objects_reclaimed;
4858   }
4859 
4860   uint humongous_regions_reclaimed() {
4861     return _humongous_regions_reclaimed;
4862   }
4863 
4864   size_t bytes_freed() const {
4865     return _freed_bytes;
4866   }
4867 };
4868 
4869 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4870   assert_at_safepoint(true);
4871 
4872   if (!G1EagerReclaimHumongousObjects ||
4873       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4874     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4875     return;
4876   }
4877 
4878   double start_time = os::elapsedTime();
4879 
4880   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4881 
4882   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4883   heap_region_iterate(&cl);
4884 
4885   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4886 
4887   G1HRPrinter* hrp = hr_printer();
4888   if (hrp->is_active()) {
4889     FreeRegionListIterator iter(&local_cleanup_list);
4890     while (iter.more_available()) {
4891       HeapRegion* hr = iter.get_next();
4892       hrp->cleanup(hr);
4893     }
4894   }
4895 
4896   prepend_to_freelist(&local_cleanup_list);
4897   decrement_summary_bytes(cl.bytes_freed());
4898 
4899   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4900                                                                     cl.humongous_objects_reclaimed());
4901 }
4902 
4903 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4904 public:
4905   virtual bool do_heap_region(HeapRegion* r) {
4906     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4907     G1CollectedHeap::heap()->clear_in_cset(r);
4908     r->set_young_index_in_cset(-1);
4909     return false;
4910   }
4911 };
4912 
4913 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4914   G1AbandonCollectionSetClosure cl;
4915   collection_set->iterate(&cl);
4916 
4917   collection_set->clear();
4918   collection_set->stop_incremental_building();
4919 }
4920 
4921 void G1CollectedHeap::set_free_regions_coming() {
4922   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4923 
4924   assert(!free_regions_coming(), "pre-condition");
4925   _free_regions_coming = true;
4926 }
4927 
4928 void G1CollectedHeap::reset_free_regions_coming() {
4929   assert(free_regions_coming(), "pre-condition");
4930 
4931   {
4932     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4933     _free_regions_coming = false;
4934     SecondaryFreeList_lock->notify_all();
4935   }
4936 
4937   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4938 }
4939 
4940 void G1CollectedHeap::wait_while_free_regions_coming() {
4941   // Most of the time we won't have to wait, so let's do a quick test
4942   // first before we take the lock.
4943   if (!free_regions_coming()) {
4944     return;
4945   }
4946 
4947   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4948 
4949   {
4950     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4951     while (free_regions_coming()) {
4952       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4953     }
4954   }
4955 
4956   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
4957 }
4958 
4959 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4960   return _allocator->is_retained_old_region(hr);
4961 }
4962 
4963 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4964   _eden.add(hr);
4965   _g1_policy->set_region_eden(hr);
4966 }
4967 
4968 #ifdef ASSERT
4969 
4970 class NoYoungRegionsClosure: public HeapRegionClosure {
4971 private:
4972   bool _success;
4973 public:
4974   NoYoungRegionsClosure() : _success(true) { }
4975   bool do_heap_region(HeapRegion* r) {
4976     if (r->is_young()) {
4977       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4978                             p2i(r->bottom()), p2i(r->end()));
4979       _success = false;
4980     }
4981     return false;
4982   }
4983   bool success() { return _success; }
4984 };
4985 
4986 bool G1CollectedHeap::check_young_list_empty() {
4987   bool ret = (young_regions_count() == 0);
4988 
4989   NoYoungRegionsClosure closure;
4990   heap_region_iterate(&closure);
4991   ret = ret && closure.success();
4992 
4993   return ret;
4994 }
4995 
4996 #endif // ASSERT
4997 
4998 class TearDownRegionSetsClosure : public HeapRegionClosure {
4999 private:
5000   HeapRegionSet *_old_set;
5001 
5002 public:
5003   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5004 
5005   bool do_heap_region(HeapRegion* r) {
5006     if (r->is_old()) {
5007       _old_set->remove(r);
5008     } else if(r->is_young()) {
5009       r->uninstall_surv_rate_group();
5010     } else {
5011       // We ignore free regions, we'll empty the free list afterwards.
5012       // We ignore humongous regions, we're not tearing down the
5013       // humongous regions set.
5014       assert(r->is_free() || r->is_humongous(),
5015              "it cannot be another type");
5016     }
5017     return false;
5018   }
5019 
5020   ~TearDownRegionSetsClosure() {
5021     assert(_old_set->is_empty(), "post-condition");
5022   }
5023 };
5024 
5025 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5026   assert_at_safepoint(true /* should_be_vm_thread */);
5027 
5028   if (!free_list_only) {
5029     TearDownRegionSetsClosure cl(&_old_set);
5030     heap_region_iterate(&cl);
5031 
5032     // Note that emptying the _young_list is postponed and instead done as
5033     // the first step when rebuilding the regions sets again. The reason for
5034     // this is that during a full GC string deduplication needs to know if
5035     // a collected region was young or old when the full GC was initiated.
5036   }
5037   _hrm.remove_all_free_regions();
5038 }
5039 
5040 void G1CollectedHeap::increase_used(size_t bytes) {
5041   _summary_bytes_used += bytes;
5042 }
5043 
5044 void G1CollectedHeap::decrease_used(size_t bytes) {
5045   assert(_summary_bytes_used >= bytes,
5046          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5047          _summary_bytes_used, bytes);
5048   _summary_bytes_used -= bytes;
5049 }
5050 
5051 void G1CollectedHeap::set_used(size_t bytes) {
5052   _summary_bytes_used = bytes;
5053 }
5054 
5055 class RebuildRegionSetsClosure : public HeapRegionClosure {
5056 private:
5057   bool            _free_list_only;
5058   HeapRegionSet*   _old_set;
5059   HeapRegionManager*   _hrm;
5060   size_t          _total_used;
5061 
5062 public:
5063   RebuildRegionSetsClosure(bool free_list_only,
5064                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5065     _free_list_only(free_list_only),
5066     _old_set(old_set), _hrm(hrm), _total_used(0) {
5067     assert(_hrm->num_free_regions() == 0, "pre-condition");
5068     if (!free_list_only) {
5069       assert(_old_set->is_empty(), "pre-condition");
5070     }
5071   }
5072 
5073   bool do_heap_region(HeapRegion* r) {
5074     if (r->is_empty()) {
5075       // Add free regions to the free list
5076       r->set_free();
5077       r->set_allocation_context(AllocationContext::system());
5078       _hrm->insert_into_free_list(r);
5079     } else if (!_free_list_only) {
5080 
5081       if (r->is_humongous()) {
5082         // We ignore humongous regions. We left the humongous set unchanged.
5083       } else {
5084         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5085         // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5086         r->move_to_old();
5087         _old_set->add(r);
5088       }
5089       _total_used += r->used();
5090     }
5091 
5092     return false;
5093   }
5094 
5095   size_t total_used() {
5096     return _total_used;
5097   }
5098 };
5099 
5100 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5101   assert_at_safepoint(true /* should_be_vm_thread */);
5102 
5103   if (!free_list_only) {
5104     _eden.clear();
5105     _survivor.clear();
5106   }
5107 
5108   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5109   heap_region_iterate(&cl);
5110 
5111   if (!free_list_only) {
5112     set_used(cl.total_used());
5113     if (_archive_allocator != NULL) {
5114       _archive_allocator->clear_used();
5115     }
5116   }
5117   assert(used_unlocked() == recalculate_used(),
5118          "inconsistent used_unlocked(), "
5119          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5120          used_unlocked(), recalculate_used());
5121 }
5122 
5123 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5124   HeapRegion* hr = heap_region_containing(p);
5125   return hr->is_in(p);
5126 }
5127 
5128 // Methods for the mutator alloc region
5129 
5130 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5131                                                       bool force) {
5132   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5133   bool should_allocate = g1_policy()->should_allocate_mutator_region();
5134   if (force || should_allocate) {
5135     HeapRegion* new_alloc_region = new_region(word_size,
5136                                               false /* is_old */,
5137                                               false /* do_expand */);
5138     if (new_alloc_region != NULL) {
5139       set_region_short_lived_locked(new_alloc_region);
5140       _hr_printer.alloc(new_alloc_region, !should_allocate);
5141       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5142       return new_alloc_region;
5143     }
5144   }
5145   return NULL;
5146 }
5147 
5148 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5149                                                   size_t allocated_bytes) {
5150   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5151   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5152 
5153   collection_set()->add_eden_region(alloc_region);
5154   increase_used(allocated_bytes);
5155   _hr_printer.retire(alloc_region);
5156   // We update the eden sizes here, when the region is retired,
5157   // instead of when it's allocated, since this is the point that its
5158   // used space has been recored in _summary_bytes_used.
5159   g1mm()->update_eden_size();
5160 }
5161 
5162 // Methods for the GC alloc regions
5163 
5164 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5165   if (dest.is_old()) {
5166     return true;
5167   } else {
5168     return survivor_regions_count() < g1_policy()->max_survivor_regions();
5169   }
5170 }
5171 
5172 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5173   assert(FreeList_lock->owned_by_self(), "pre-condition");
5174 
5175   if (!has_more_regions(dest)) {
5176     return NULL;
5177   }
5178 
5179   const bool is_survivor = dest.is_young();
5180 
5181   HeapRegion* new_alloc_region = new_region(word_size,
5182                                             !is_survivor,
5183                                             true /* do_expand */);
5184   if (new_alloc_region != NULL) {
5185     // We really only need to do this for old regions given that we
5186     // should never scan survivors. But it doesn't hurt to do it
5187     // for survivors too.
5188     new_alloc_region->record_timestamp();
5189     if (is_survivor) {
5190       new_alloc_region->set_survivor();
5191       _survivor.add(new_alloc_region);
5192       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5193     } else {
5194       new_alloc_region->set_old();
5195       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5196     }
5197     _hr_printer.alloc(new_alloc_region);
5198     bool during_im = collector_state()->during_initial_mark_pause();
5199     new_alloc_region->note_start_of_copying(during_im);
5200     return new_alloc_region;
5201   }
5202   return NULL;
5203 }
5204 
5205 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5206                                              size_t allocated_bytes,
5207                                              InCSetState dest) {
5208   bool during_im = collector_state()->during_initial_mark_pause();
5209   alloc_region->note_end_of_copying(during_im);
5210   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5211   if (dest.is_old()) {
5212     _old_set.add(alloc_region);
5213   }
5214   _hr_printer.retire(alloc_region);
5215 }
5216 
5217 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5218   bool expanded = false;
5219   uint index = _hrm.find_highest_free(&expanded);
5220 
5221   if (index != G1_NO_HRM_INDEX) {
5222     if (expanded) {
5223       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5224                                 HeapRegion::GrainWords * HeapWordSize);
5225     }
5226     _hrm.allocate_free_regions_starting_at(index, 1);
5227     return region_at(index);
5228   }
5229   return NULL;
5230 }
5231 
5232 // Optimized nmethod scanning
5233 
5234 class RegisterNMethodOopClosure: public OopClosure {
5235   G1CollectedHeap* _g1h;
5236   nmethod* _nm;
5237 
5238   template <class T> void do_oop_work(T* p) {
5239     T heap_oop = oopDesc::load_heap_oop(p);
5240     if (!oopDesc::is_null(heap_oop)) {
5241       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5242       HeapRegion* hr = _g1h->heap_region_containing(obj);
5243       assert(!hr->is_continues_humongous(),
5244              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5245              " starting at " HR_FORMAT,
5246              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5247 
5248       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5249       hr->add_strong_code_root_locked(_nm);
5250     }
5251   }
5252 
5253 public:
5254   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5255     _g1h(g1h), _nm(nm) {}
5256 
5257   void do_oop(oop* p)       { do_oop_work(p); }
5258   void do_oop(narrowOop* p) { do_oop_work(p); }
5259 };
5260 
5261 class UnregisterNMethodOopClosure: public OopClosure {
5262   G1CollectedHeap* _g1h;
5263   nmethod* _nm;
5264 
5265   template <class T> void do_oop_work(T* p) {
5266     T heap_oop = oopDesc::load_heap_oop(p);
5267     if (!oopDesc::is_null(heap_oop)) {
5268       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5269       HeapRegion* hr = _g1h->heap_region_containing(obj);
5270       assert(!hr->is_continues_humongous(),
5271              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5272              " starting at " HR_FORMAT,
5273              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5274 
5275       hr->remove_strong_code_root(_nm);
5276     }
5277   }
5278 
5279 public:
5280   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5281     _g1h(g1h), _nm(nm) {}
5282 
5283   void do_oop(oop* p)       { do_oop_work(p); }
5284   void do_oop(narrowOop* p) { do_oop_work(p); }
5285 };
5286 
5287 // Returns true if the reference points to an object that
5288 // can move in an incremental collection.
5289 bool G1CollectedHeap::is_scavengable(oop obj) {
5290   HeapRegion* hr = heap_region_containing(obj);
5291   return !hr->is_pinned();
5292 }
5293 
5294 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5295   guarantee(nm != NULL, "sanity");
5296   RegisterNMethodOopClosure reg_cl(this, nm);
5297   nm->oops_do(&reg_cl);
5298 }
5299 
5300 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5301   guarantee(nm != NULL, "sanity");
5302   UnregisterNMethodOopClosure reg_cl(this, nm);
5303   nm->oops_do(&reg_cl, true);
5304 }
5305 
5306 void G1CollectedHeap::purge_code_root_memory() {
5307   double purge_start = os::elapsedTime();
5308   G1CodeRootSet::purge();
5309   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5310   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5311 }
5312 
5313 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5314   G1CollectedHeap* _g1h;
5315 
5316 public:
5317   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5318     _g1h(g1h) {}
5319 
5320   void do_code_blob(CodeBlob* cb) {
5321     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5322     if (nm == NULL) {
5323       return;
5324     }
5325 
5326     if (ScavengeRootsInCode) {
5327       _g1h->register_nmethod(nm);
5328     }
5329   }
5330 };
5331 
5332 void G1CollectedHeap::rebuild_strong_code_roots() {
5333   RebuildStrongCodeRootClosure blob_cl(this);
5334   CodeCache::blobs_do(&blob_cl);
5335 }
5336 
5337 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5338   GrowableArray<GCMemoryManager*> memory_managers(2);
5339   memory_managers.append(&_memory_manager);
5340   memory_managers.append(&_full_gc_memory_manager);
5341   return memory_managers;
5342 }
5343 
5344 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5345   GrowableArray<MemoryPool*> memory_pools(3);
5346   memory_pools.append(_eden_pool);
5347   memory_pools.append(_survivor_pool);
5348   memory_pools.append(_old_pool);
5349   return memory_pools;
5350 }