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/gcHeapSummary.hpp"
  63 #include "gc/shared/gcId.hpp"
  64 #include "gc/shared/gcLocker.inline.hpp"
  65 #include "gc/shared/gcTimer.hpp"
  66 #include "gc/shared/gcTrace.hpp"
  67 #include "gc/shared/gcTraceTime.inline.hpp"
  68 #include "gc/shared/generationSpec.hpp"
  69 #include "gc/shared/isGCActiveMark.hpp"
  70 #include "gc/shared/preservedMarks.inline.hpp"
  71 #include "gc/shared/suspendibleThreadSet.hpp"
  72 #include "gc/shared/referenceProcessor.inline.hpp"
  73 #include "gc/shared/taskqueue.inline.hpp"
  74 #include "gc/shared/weakProcessor.hpp"
  75 #include "logging/log.hpp"
  76 #include "memory/allocation.hpp"
  77 #include "memory/iterator.hpp"
  78 #include "memory/resourceArea.hpp"
  79 #include "oops/oop.inline.hpp"
  80 #include "prims/resolvedMethodTable.hpp"
  81 #include "runtime/atomic.hpp"
  82 #include "runtime/init.hpp"
  83 #include "runtime/orderAccess.inline.hpp"
  84 #include "runtime/threadSMR.hpp"
  85 #include "runtime/vmThread.hpp"
  86 #include "utilities/align.hpp"
  87 #include "utilities/globalDefinitions.hpp"
  88 #include "utilities/stack.inline.hpp"
  89 
  90 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  91 
  92 // INVARIANTS/NOTES
  93 //
  94 // All allocation activity covered by the G1CollectedHeap interface is
  95 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  96 // and allocate_new_tlab, which are the "entry" points to the
  97 // allocation code from the rest of the JVM.  (Note that this does not
  98 // apply to TLAB allocation, which is not part of this interface: it
  99 // is done by clients of this interface.)
 100 
 101 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 102  private:
 103   size_t _num_dirtied;
 104   G1CollectedHeap* _g1h;
 105   G1SATBCardTableLoggingModRefBS* _g1_bs;
 106 
 107   HeapRegion* region_for_card(jbyte* card_ptr) const {
 108     return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
 109   }
 110 
 111   bool will_become_free(HeapRegion* hr) const {
 112     // A region will be freed by free_collection_set if the region is in the
 113     // collection set and has not had an evacuation failure.
 114     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 115   }
 116 
 117  public:
 118   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 119     _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
 120 
 121   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 122     HeapRegion* hr = region_for_card(card_ptr);
 123 
 124     // Should only dirty cards in regions that won't be freed.
 125     if (!will_become_free(hr)) {
 126       *card_ptr = CardTableModRefBS::dirty_card_val();
 127       _num_dirtied++;
 128     }
 129 
 130     return true;
 131   }
 132 
 133   size_t num_dirtied()   const { return _num_dirtied; }
 134 };
 135 
 136 
 137 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 138   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 139 }
 140 
 141 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 142   // The from card cache is not the memory that is actually committed. So we cannot
 143   // take advantage of the zero_filled parameter.
 144   reset_from_card_cache(start_idx, num_regions);
 145 }
 146 
 147 
 148 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 149                                              MemRegion mr) {
 150   return new HeapRegion(hrs_index, bot(), mr);
 151 }
 152 
 153 // Private methods.
 154 
 155 HeapRegion*
 156 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 157   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 158   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 159     if (!_secondary_free_list.is_empty()) {
 160       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 161                                       "secondary_free_list has %u entries",
 162                                       _secondary_free_list.length());
 163       // It looks as if there are free regions available on the
 164       // secondary_free_list. Let's move them to the free_list and try
 165       // again to allocate from it.
 166       append_secondary_free_list();
 167 
 168       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 169              "empty we should have moved at least one entry to the free_list");
 170       HeapRegion* res = _hrm.allocate_free_region(is_old);
 171       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 172                                       "allocated " HR_FORMAT " from secondary_free_list",
 173                                       HR_FORMAT_PARAMS(res));
 174       return res;
 175     }
 176 
 177     // Wait here until we get notified either when (a) there are no
 178     // more free regions coming or (b) some regions have been moved on
 179     // the secondary_free_list.
 180     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 181   }
 182 
 183   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 184                                   "could not allocate from secondary_free_list");
 185   return NULL;
 186 }
 187 
 188 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 189   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 190          "the only time we use this to allocate a humongous region is "
 191          "when we are allocating a single humongous region");
 192 
 193   HeapRegion* res;
 194   if (G1StressConcRegionFreeing) {
 195     if (!_secondary_free_list.is_empty()) {
 196       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 197                                       "forced to look at the secondary_free_list");
 198       res = new_region_try_secondary_free_list(is_old);
 199       if (res != NULL) {
 200         return res;
 201       }
 202     }
 203   }
 204 
 205   res = _hrm.allocate_free_region(is_old);
 206 
 207   if (res == NULL) {
 208     log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 209                                     "res == NULL, trying the secondary_free_list");
 210     res = new_region_try_secondary_free_list(is_old);
 211   }
 212   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 213     // Currently, only attempts to allocate GC alloc regions set
 214     // do_expand to true. So, we should only reach here during a
 215     // safepoint. If this assumption changes we might have to
 216     // reconsider the use of _expand_heap_after_alloc_failure.
 217     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 218 
 219     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 220                               word_size * HeapWordSize);
 221 
 222     if (expand(word_size * HeapWordSize)) {
 223       // Given that expand() succeeded in expanding the heap, and we
 224       // always expand the heap by an amount aligned to the heap
 225       // region size, the free list should in theory not be empty.
 226       // In either case allocate_free_region() will check for NULL.
 227       res = _hrm.allocate_free_region(is_old);
 228     } else {
 229       _expand_heap_after_alloc_failure = false;
 230     }
 231   }
 232   return res;
 233 }
 234 
 235 HeapWord*
 236 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 237                                                            uint num_regions,
 238                                                            size_t word_size,
 239                                                            AllocationContext_t context) {
 240   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 241   assert(is_humongous(word_size), "word_size should be humongous");
 242   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 243 
 244   // Index of last region in the series.
 245   uint last = first + num_regions - 1;
 246 
 247   // We need to initialize the region(s) we just discovered. This is
 248   // a bit tricky given that it can happen concurrently with
 249   // refinement threads refining cards on these regions and
 250   // potentially wanting to refine the BOT as they are scanning
 251   // those cards (this can happen shortly after a cleanup; see CR
 252   // 6991377). So we have to set up the region(s) carefully and in
 253   // a specific order.
 254 
 255   // The word size sum of all the regions we will allocate.
 256   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 257   assert(word_size <= word_size_sum, "sanity");
 258 
 259   // This will be the "starts humongous" region.
 260   HeapRegion* first_hr = region_at(first);
 261   // The header of the new object will be placed at the bottom of
 262   // the first region.
 263   HeapWord* new_obj = first_hr->bottom();
 264   // This will be the new top of the new object.
 265   HeapWord* obj_top = new_obj + word_size;
 266 
 267   // First, we need to zero the header of the space that we will be
 268   // allocating. When we update top further down, some refinement
 269   // threads might try to scan the region. By zeroing the header we
 270   // ensure that any thread that will try to scan the region will
 271   // come across the zero klass word and bail out.
 272   //
 273   // NOTE: It would not have been correct to have used
 274   // CollectedHeap::fill_with_object() and make the space look like
 275   // an int array. The thread that is doing the allocation will
 276   // later update the object header to a potentially different array
 277   // type and, for a very short period of time, the klass and length
 278   // fields will be inconsistent. This could cause a refinement
 279   // thread to calculate the object size incorrectly.
 280   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 281 
 282   // Next, pad out the unused tail of the last region with filler
 283   // objects, for improved usage accounting.
 284   // How many words we use for filler objects.
 285   size_t word_fill_size = word_size_sum - word_size;
 286 
 287   // How many words memory we "waste" which cannot hold a filler object.
 288   size_t words_not_fillable = 0;
 289 
 290   if (word_fill_size >= min_fill_size()) {
 291     fill_with_objects(obj_top, word_fill_size);
 292   } else if (word_fill_size > 0) {
 293     // We have space to fill, but we cannot fit an object there.
 294     words_not_fillable = word_fill_size;
 295     word_fill_size = 0;
 296   }
 297 
 298   // We will set up the first region as "starts humongous". This
 299   // will also update the BOT covering all the regions to reflect
 300   // that there is a single object that starts at the bottom of the
 301   // first region.
 302   first_hr->set_starts_humongous(obj_top, word_fill_size);
 303   first_hr->set_allocation_context(context);
 304   // Then, if there are any, we will set up the "continues
 305   // humongous" regions.
 306   HeapRegion* hr = NULL;
 307   for (uint i = first + 1; i <= last; ++i) {
 308     hr = region_at(i);
 309     hr->set_continues_humongous(first_hr);
 310     hr->set_allocation_context(context);
 311   }
 312 
 313   // Up to this point no concurrent thread would have been able to
 314   // do any scanning on any region in this series. All the top
 315   // fields still point to bottom, so the intersection between
 316   // [bottom,top] and [card_start,card_end] will be empty. Before we
 317   // update the top fields, we'll do a storestore to make sure that
 318   // no thread sees the update to top before the zeroing of the
 319   // object header and the BOT initialization.
 320   OrderAccess::storestore();
 321 
 322   // Now, we will update the top fields of the "continues humongous"
 323   // regions except the last one.
 324   for (uint i = first; i < last; ++i) {
 325     hr = region_at(i);
 326     hr->set_top(hr->end());
 327   }
 328 
 329   hr = region_at(last);
 330   // If we cannot fit a filler object, we must set top to the end
 331   // of the humongous object, otherwise we cannot iterate the heap
 332   // and the BOT will not be complete.
 333   hr->set_top(hr->end() - words_not_fillable);
 334 
 335   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 336          "obj_top should be in last region");
 337 
 338   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 339 
 340   assert(words_not_fillable == 0 ||
 341          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 342          "Miscalculation in humongous allocation");
 343 
 344   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 345 
 346   for (uint i = first; i <= last; ++i) {
 347     hr = region_at(i);
 348     _humongous_set.add(hr);
 349     _hr_printer.alloc(hr);
 350   }
 351 
 352   return new_obj;
 353 }
 354 
 355 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 356   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 357   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 358 }
 359 
 360 // If could fit into free regions w/o expansion, try.
 361 // Otherwise, if can expand, do so.
 362 // Otherwise, if using ex regions might help, try with ex given back.
 363 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 364   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 365 
 366   _verifier->verify_region_sets_optional();
 367 
 368   uint first = G1_NO_HRM_INDEX;
 369   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 370 
 371   if (obj_regions == 1) {
 372     // Only one region to allocate, try to use a fast path by directly allocating
 373     // from the free lists. Do not try to expand here, we will potentially do that
 374     // later.
 375     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 376     if (hr != NULL) {
 377       first = hr->hrm_index();
 378     }
 379   } else {
 380     // We can't allocate humongous regions spanning more than one region while
 381     // cleanupComplete() is running, since some of the regions we find to be
 382     // empty might not yet be added to the free list. It is not straightforward
 383     // to know in which list they are on so that we can remove them. We only
 384     // need to do this if we need to allocate more than one region to satisfy the
 385     // current humongous allocation request. If we are only allocating one region
 386     // we use the one-region region allocation code (see above), that already
 387     // potentially waits for regions from the secondary free list.
 388     wait_while_free_regions_coming();
 389     append_secondary_free_list_if_not_empty_with_lock();
 390 
 391     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 392     // are lucky enough to find some.
 393     first = _hrm.find_contiguous_only_empty(obj_regions);
 394     if (first != G1_NO_HRM_INDEX) {
 395       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 396     }
 397   }
 398 
 399   if (first == G1_NO_HRM_INDEX) {
 400     // Policy: We could not find enough regions for the humongous object in the
 401     // free list. Look through the heap to find a mix of free and uncommitted regions.
 402     // If so, try expansion.
 403     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 404     if (first != G1_NO_HRM_INDEX) {
 405       // We found something. Make sure these regions are committed, i.e. expand
 406       // the heap. Alternatively we could do a defragmentation GC.
 407       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 408                                     word_size * HeapWordSize);
 409 
 410       _hrm.expand_at(first, obj_regions, workers());
 411       g1_policy()->record_new_heap_size(num_regions());
 412 
 413 #ifdef ASSERT
 414       for (uint i = first; i < first + obj_regions; ++i) {
 415         HeapRegion* hr = region_at(i);
 416         assert(hr->is_free(), "sanity");
 417         assert(hr->is_empty(), "sanity");
 418         assert(is_on_master_free_list(hr), "sanity");
 419       }
 420 #endif
 421       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 422     } else {
 423       // Policy: Potentially trigger a defragmentation GC.
 424     }
 425   }
 426 
 427   HeapWord* result = NULL;
 428   if (first != G1_NO_HRM_INDEX) {
 429     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 430                                                        word_size, context);
 431     assert(result != NULL, "it should always return a valid result");
 432 
 433     // A successful humongous object allocation changes the used space
 434     // information of the old generation so we need to recalculate the
 435     // sizes and update the jstat counters here.
 436     g1mm()->update_sizes();
 437   }
 438 
 439   _verifier->verify_region_sets_optional();
 440 
 441   return result;
 442 }
 443 
 444 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 445   assert_heap_not_locked_and_not_at_safepoint();
 446   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 447 
 448   return attempt_allocation(word_size);
 449 }
 450 
 451 HeapWord*
 452 G1CollectedHeap::mem_allocate(size_t word_size,
 453                               bool*  gc_overhead_limit_was_exceeded) {
 454   assert_heap_not_locked_and_not_at_safepoint();
 455 
 456   if (is_humongous(word_size)) {
 457     return attempt_allocation_humongous(word_size);
 458   }
 459   return attempt_allocation(word_size);
 460 }
 461 
 462 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 463                                                    AllocationContext_t context) {
 464   ResourceMark rm; // For retrieving the thread names in log messages.
 465 
 466   // Make sure you read the note in attempt_allocation_humongous().
 467 
 468   assert_heap_not_locked_and_not_at_safepoint();
 469   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 470          "be called for humongous allocation requests");
 471 
 472   // We should only get here after the first-level allocation attempt
 473   // (attempt_allocation()) failed to allocate.
 474 
 475   // We will loop until a) we manage to successfully perform the
 476   // allocation or b) we successfully schedule a collection which
 477   // fails to perform the allocation. b) is the only case when we'll
 478   // return NULL.
 479   HeapWord* result = NULL;
 480   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 481     bool should_try_gc;
 482     uint gc_count_before;
 483 
 484     {
 485       MutexLockerEx x(Heap_lock);
 486       result = _allocator->attempt_allocation_locked(word_size, context);
 487       if (result != NULL) {
 488         return result;
 489       }
 490 
 491       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 492       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 493       // waiting because the GCLocker is active to not wait too long.
 494       if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
 495         // No need for an ergo message here, can_expand_young_list() does this when
 496         // it returns true.
 497         result = _allocator->attempt_allocation_force(word_size, context);
 498         if (result != NULL) {
 499           return result;
 500         }
 501       }
 502       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 503       // the GCLocker initiated GC has been performed and then retry. This includes
 504       // the case when the GC Locker is not active but has not been performed.
 505       should_try_gc = !GCLocker::needs_gc();
 506       // Read the GC count while still holding the Heap_lock.
 507       gc_count_before = total_collections();
 508     }
 509 
 510     if (should_try_gc) {
 511       bool succeeded;
 512       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 513                                    GCCause::_g1_inc_collection_pause);
 514       if (result != NULL) {
 515         assert(succeeded, "only way to get back a non-NULL result");
 516         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 517                              Thread::current()->name(), p2i(result));
 518         return result;
 519       }
 520 
 521       if (succeeded) {
 522         // We successfully scheduled a collection which failed to allocate. No
 523         // point in trying to allocate further. We'll just return NULL.
 524         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 525                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 526         return NULL;
 527       }
 528       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 529                            Thread::current()->name(), word_size);
 530     } else {
 531       // Failed to schedule a collection.
 532       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 533         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 534                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 535         return NULL;
 536       }
 537       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 538       // The GCLocker is either active or the GCLocker initiated
 539       // GC has not yet been performed. Stall until it is and
 540       // then retry the allocation.
 541       GCLocker::stall_until_clear();
 542       gclocker_retry_count += 1;
 543     }
 544 
 545     // We can reach here if we were unsuccessful in scheduling a
 546     // collection (because another thread beat us to it) or if we were
 547     // stalled due to the GC locker. In either can we should retry the
 548     // allocation attempt in case another thread successfully
 549     // performed a collection and reclaimed enough space. We do the
 550     // first attempt (without holding the Heap_lock) here and the
 551     // follow-on attempt will be at the start of the next loop
 552     // iteration (after taking the Heap_lock).
 553 
 554     result = _allocator->attempt_allocation(word_size, context);
 555     if (result != NULL) {
 556       return result;
 557     }
 558 
 559     // Give a warning if we seem to be looping forever.
 560     if ((QueuedAllocationWarningCount > 0) &&
 561         (try_count % QueuedAllocationWarningCount == 0)) {
 562       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 563                              Thread::current()->name(), try_count, word_size);
 564     }
 565   }
 566 
 567   ShouldNotReachHere();
 568   return NULL;
 569 }
 570 
 571 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 572   assert_at_safepoint(true /* should_be_vm_thread */);
 573   if (_archive_allocator == NULL) {
 574     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 575   }
 576 }
 577 
 578 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 579   // Allocations in archive regions cannot be of a size that would be considered
 580   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 581   // may be different at archive-restore time.
 582   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 583 }
 584 
 585 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 586   assert_at_safepoint(true /* should_be_vm_thread */);
 587   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 588   if (is_archive_alloc_too_large(word_size)) {
 589     return NULL;
 590   }
 591   return _archive_allocator->archive_mem_allocate(word_size);
 592 }
 593 
 594 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 595                                               size_t end_alignment_in_bytes) {
 596   assert_at_safepoint(true /* should_be_vm_thread */);
 597   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 598 
 599   // Call complete_archive to do the real work, filling in the MemRegion
 600   // array with the archive regions.
 601   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 602   delete _archive_allocator;
 603   _archive_allocator = NULL;
 604 }
 605 
 606 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 607   assert(ranges != NULL, "MemRegion array NULL");
 608   assert(count != 0, "No MemRegions provided");
 609   MemRegion reserved = _hrm.reserved();
 610   for (size_t i = 0; i < count; i++) {
 611     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 612       return false;
 613     }
 614   }
 615   return true;
 616 }
 617 
 618 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 619                                             size_t count,
 620                                             bool open) {
 621   assert(!is_init_completed(), "Expect to be called at JVM init time");
 622   assert(ranges != NULL, "MemRegion array NULL");
 623   assert(count != 0, "No MemRegions provided");
 624   MutexLockerEx x(Heap_lock);
 625 
 626   MemRegion reserved = _hrm.reserved();
 627   HeapWord* prev_last_addr = NULL;
 628   HeapRegion* prev_last_region = NULL;
 629 
 630   // Temporarily disable pretouching of heap pages. This interface is used
 631   // when mmap'ing archived heap data in, so pre-touching is wasted.
 632   FlagSetting fs(AlwaysPreTouch, false);
 633 
 634   // Enable archive object checking used by G1MarkSweep. We have to let it know
 635   // about each archive range, so that objects in those ranges aren't marked.
 636   G1ArchiveAllocator::enable_archive_object_check();
 637 
 638   // For each specified MemRegion range, allocate the corresponding G1
 639   // regions and mark them as archive regions. We expect the ranges
 640   // in ascending starting address order, without overlap.
 641   for (size_t i = 0; i < count; i++) {
 642     MemRegion curr_range = ranges[i];
 643     HeapWord* start_address = curr_range.start();
 644     size_t word_size = curr_range.word_size();
 645     HeapWord* last_address = curr_range.last();
 646     size_t commits = 0;
 647 
 648     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 649               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 650               p2i(start_address), p2i(last_address));
 651     guarantee(start_address > prev_last_addr,
 652               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 653               p2i(start_address), p2i(prev_last_addr));
 654     prev_last_addr = last_address;
 655 
 656     // Check for ranges that start in the same G1 region in which the previous
 657     // range ended, and adjust the start address so we don't try to allocate
 658     // the same region again. If the current range is entirely within that
 659     // region, skip it, just adjusting the recorded top.
 660     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 661     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 662       start_address = start_region->end();
 663       if (start_address > last_address) {
 664         increase_used(word_size * HeapWordSize);
 665         start_region->set_top(last_address + 1);
 666         continue;
 667       }
 668       start_region->set_top(start_address);
 669       curr_range = MemRegion(start_address, last_address + 1);
 670       start_region = _hrm.addr_to_region(start_address);
 671     }
 672 
 673     // Perform the actual region allocation, exiting if it fails.
 674     // Then note how much new space we have allocated.
 675     if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
 676       return false;
 677     }
 678     increase_used(word_size * HeapWordSize);
 679     if (commits != 0) {
 680       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 681                                 HeapRegion::GrainWords * HeapWordSize * commits);
 682 
 683     }
 684 
 685     // Mark each G1 region touched by the range as archive, add it to
 686     // the old set, and set the allocation context and top.
 687     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 688     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 689     prev_last_region = last_region;
 690 
 691     while (curr_region != NULL) {
 692       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 693              "Region already in use (index %u)", curr_region->hrm_index());
 694       curr_region->set_allocation_context(AllocationContext::system());
 695       if (open) {
 696         curr_region->set_open_archive();
 697       } else {
 698         curr_region->set_closed_archive();
 699       }
 700       _hr_printer.alloc(curr_region);
 701       _old_set.add(curr_region);
 702       HeapWord* top;
 703       HeapRegion* next_region;
 704       if (curr_region != last_region) {
 705         top = curr_region->end();
 706         next_region = _hrm.next_region_in_heap(curr_region);
 707       } else {
 708         top = last_address + 1;
 709         next_region = NULL;
 710       }
 711       curr_region->set_top(top);
 712       curr_region->set_first_dead(top);
 713       curr_region->set_end_of_live(top);
 714       curr_region = next_region;
 715     }
 716 
 717     // Notify mark-sweep of the archive
 718     G1ArchiveAllocator::set_range_archive(curr_range, open);
 719   }
 720   return true;
 721 }
 722 
 723 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 724   assert(!is_init_completed(), "Expect to be called at JVM init time");
 725   assert(ranges != NULL, "MemRegion array NULL");
 726   assert(count != 0, "No MemRegions provided");
 727   MemRegion reserved = _hrm.reserved();
 728   HeapWord *prev_last_addr = NULL;
 729   HeapRegion* prev_last_region = NULL;
 730 
 731   // For each MemRegion, create filler objects, if needed, in the G1 regions
 732   // that contain the address range. The address range actually within the
 733   // MemRegion will not be modified. That is assumed to have been initialized
 734   // elsewhere, probably via an mmap of archived heap data.
 735   MutexLockerEx x(Heap_lock);
 736   for (size_t i = 0; i < count; i++) {
 737     HeapWord* start_address = ranges[i].start();
 738     HeapWord* last_address = ranges[i].last();
 739 
 740     assert(reserved.contains(start_address) && reserved.contains(last_address),
 741            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 742            p2i(start_address), p2i(last_address));
 743     assert(start_address > prev_last_addr,
 744            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 745            p2i(start_address), p2i(prev_last_addr));
 746 
 747     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 748     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 749     HeapWord* bottom_address = start_region->bottom();
 750 
 751     // Check for a range beginning in the same region in which the
 752     // previous one ended.
 753     if (start_region == prev_last_region) {
 754       bottom_address = prev_last_addr + 1;
 755     }
 756 
 757     // Verify that the regions were all marked as archive regions by
 758     // alloc_archive_regions.
 759     HeapRegion* curr_region = start_region;
 760     while (curr_region != NULL) {
 761       guarantee(curr_region->is_archive(),
 762                 "Expected archive region at index %u", curr_region->hrm_index());
 763       if (curr_region != last_region) {
 764         curr_region = _hrm.next_region_in_heap(curr_region);
 765       } else {
 766         curr_region = NULL;
 767       }
 768     }
 769 
 770     prev_last_addr = last_address;
 771     prev_last_region = last_region;
 772 
 773     // Fill the memory below the allocated range with dummy object(s),
 774     // if the region bottom does not match the range start, or if the previous
 775     // range ended within the same G1 region, and there is a gap.
 776     if (start_address != bottom_address) {
 777       size_t fill_size = pointer_delta(start_address, bottom_address);
 778       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 779       increase_used(fill_size * HeapWordSize);
 780     }
 781   }
 782 }
 783 
 784 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) {
 785   assert_heap_not_locked_and_not_at_safepoint();
 786   assert(!is_humongous(word_size), "attempt_allocation() should not "
 787          "be called for humongous allocation requests");
 788 
 789   AllocationContext_t context = AllocationContext::current();
 790   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 791 
 792   if (result == NULL) {
 793     result = attempt_allocation_slow(word_size, context);
 794   }
 795   assert_heap_not_locked();
 796   if (result != NULL) {
 797     dirty_young_block(result, word_size);
 798   }
 799   return result;
 800 }
 801 
 802 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 803   assert(!is_init_completed(), "Expect to be called at JVM init time");
 804   assert(ranges != NULL, "MemRegion array NULL");
 805   assert(count != 0, "No MemRegions provided");
 806   MemRegion reserved = _hrm.reserved();
 807   HeapWord* prev_last_addr = NULL;
 808   HeapRegion* prev_last_region = NULL;
 809   size_t size_used = 0;
 810   size_t uncommitted_regions = 0;
 811 
 812   // For each Memregion, free the G1 regions that constitute it, and
 813   // notify mark-sweep that the range is no longer to be considered 'archive.'
 814   MutexLockerEx x(Heap_lock);
 815   for (size_t i = 0; i < count; i++) {
 816     HeapWord* start_address = ranges[i].start();
 817     HeapWord* last_address = ranges[i].last();
 818 
 819     assert(reserved.contains(start_address) && reserved.contains(last_address),
 820            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 821            p2i(start_address), p2i(last_address));
 822     assert(start_address > prev_last_addr,
 823            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 824            p2i(start_address), p2i(prev_last_addr));
 825     size_used += ranges[i].byte_size();
 826     prev_last_addr = last_address;
 827 
 828     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 829     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 830 
 831     // Check for ranges that start in the same G1 region in which the previous
 832     // range ended, and adjust the start address so we don't try to free
 833     // the same region again. If the current range is entirely within that
 834     // region, skip it.
 835     if (start_region == prev_last_region) {
 836       start_address = start_region->end();
 837       if (start_address > last_address) {
 838         continue;
 839       }
 840       start_region = _hrm.addr_to_region(start_address);
 841     }
 842     prev_last_region = last_region;
 843 
 844     // After verifying that each region was marked as an archive region by
 845     // alloc_archive_regions, set it free and empty and uncommit it.
 846     HeapRegion* curr_region = start_region;
 847     while (curr_region != NULL) {
 848       guarantee(curr_region->is_archive(),
 849                 "Expected archive region at index %u", curr_region->hrm_index());
 850       uint curr_index = curr_region->hrm_index();
 851       _old_set.remove(curr_region);
 852       curr_region->set_free();
 853       curr_region->set_top(curr_region->bottom());
 854       if (curr_region != last_region) {
 855         curr_region = _hrm.next_region_in_heap(curr_region);
 856       } else {
 857         curr_region = NULL;
 858       }
 859       _hrm.shrink_at(curr_index, 1);
 860       uncommitted_regions++;
 861     }
 862 
 863     // Notify mark-sweep that this is no longer an archive range.
 864     G1ArchiveAllocator::set_range_archive(ranges[i], false);
 865   }
 866 
 867   if (uncommitted_regions != 0) {
 868     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 869                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 870   }
 871   decrease_used(size_used);
 872 }
 873 
 874 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 875   ResourceMark rm; // For retrieving the thread names in log messages.
 876 
 877   // The structure of this method has a lot of similarities to
 878   // attempt_allocation_slow(). The reason these two were not merged
 879   // into a single one is that such a method would require several "if
 880   // allocation is not humongous do this, otherwise do that"
 881   // conditional paths which would obscure its flow. In fact, an early
 882   // version of this code did use a unified method which was harder to
 883   // follow and, as a result, it had subtle bugs that were hard to
 884   // track down. So keeping these two methods separate allows each to
 885   // be more readable. It will be good to keep these two in sync as
 886   // much as possible.
 887 
 888   assert_heap_not_locked_and_not_at_safepoint();
 889   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 890          "should only be called for humongous allocations");
 891 
 892   // Humongous objects can exhaust the heap quickly, so we should check if we
 893   // need to start a marking cycle at each humongous object allocation. We do
 894   // the check before we do the actual allocation. The reason for doing it
 895   // before the allocation is that we avoid having to keep track of the newly
 896   // allocated memory while we do a GC.
 897   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 898                                            word_size)) {
 899     collect(GCCause::_g1_humongous_allocation);
 900   }
 901 
 902   // We will loop until a) we manage to successfully perform the
 903   // allocation or b) we successfully schedule a collection which
 904   // fails to perform the allocation. b) is the only case when we'll
 905   // return NULL.
 906   HeapWord* result = NULL;
 907   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 908     bool should_try_gc;
 909     uint gc_count_before;
 910 
 911 
 912     {
 913       MutexLockerEx x(Heap_lock);
 914 
 915       // Given that humongous objects are not allocated in young
 916       // regions, we'll first try to do the allocation without doing a
 917       // collection hoping that there's enough space in the heap.
 918       result = humongous_obj_allocate(word_size, AllocationContext::current());
 919       if (result != NULL) {
 920         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 921         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 922         return result;
 923       }
 924 
 925       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 926       // the GCLocker initiated GC has been performed and then retry. This includes
 927       // the case when the GC Locker is not active but has not been performed.
 928       should_try_gc = !GCLocker::needs_gc();
 929       // Read the GC count while still holding the Heap_lock.
 930       gc_count_before = total_collections();
 931     }
 932 
 933     if (should_try_gc) {
 934       bool succeeded;
 935       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 936                                    GCCause::_g1_humongous_allocation);
 937       if (result != NULL) {
 938         assert(succeeded, "only way to get back a non-NULL result");
 939         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 940                              Thread::current()->name(), p2i(result));
 941         return result;
 942       }
 943 
 944       if (succeeded) {
 945         // We successfully scheduled a collection which failed to allocate. No
 946         // point in trying to allocate further. We'll just return NULL.
 947         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 948                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 949         return NULL;
 950       }
 951       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 952                            Thread::current()->name(), word_size);
 953     } else {
 954       // Failed to schedule a collection.
 955       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 956         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 957                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 958         return NULL;
 959       }
 960       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 961       // The GCLocker is either active or the GCLocker initiated
 962       // GC has not yet been performed. Stall until it is and
 963       // then retry the allocation.
 964       GCLocker::stall_until_clear();
 965       gclocker_retry_count += 1;
 966     }
 967 
 968 
 969     // We can reach here if we were unsuccessful in scheduling a
 970     // collection (because another thread beat us to it) or if we were
 971     // stalled due to the GC locker. In either can we should retry the
 972     // allocation attempt in case another thread successfully
 973     // performed a collection and reclaimed enough space. 
 974     // Humongous object allocation always needs a lock, so we wait for the retry
 975     // in the next iteration of the loop, unlike for the regular iteration case.
 976     // Give a warning if we seem to be looping forever.
 977 
 978     if ((QueuedAllocationWarningCount > 0) &&
 979         (try_count % QueuedAllocationWarningCount == 0)) {
 980       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 981                              Thread::current()->name(), try_count, word_size);
 982     }
 983   }
 984 
 985   ShouldNotReachHere();
 986   return NULL;
 987 }
 988 
 989 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 990                                                            AllocationContext_t context,
 991                                                            bool expect_null_mutator_alloc_region) {
 992   assert_at_safepoint(true /* should_be_vm_thread */);
 993   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
 994          "the current alloc region was unexpectedly found to be non-NULL");
 995 
 996   if (!is_humongous(word_size)) {
 997     return _allocator->attempt_allocation_locked(word_size, context);
 998   } else {
 999     HeapWord* result = humongous_obj_allocate(word_size, context);
1000     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1001       collector_state()->set_initiate_conc_mark_if_possible(true);
1002     }
1003     return result;
1004   }
1005 
1006   ShouldNotReachHere();
1007 }
1008 
1009 class PostCompactionPrinterClosure: public HeapRegionClosure {
1010 private:
1011   G1HRPrinter* _hr_printer;
1012 public:
1013   bool doHeapRegion(HeapRegion* hr) {
1014     assert(!hr->is_young(), "not expecting to find young regions");
1015     _hr_printer->post_compaction(hr);
1016     return false;
1017   }
1018 
1019   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1020     : _hr_printer(hr_printer) { }
1021 };
1022 
1023 void G1CollectedHeap::print_hrm_post_compaction() {
1024   if (_hr_printer.is_active()) {
1025     PostCompactionPrinterClosure cl(hr_printer());
1026     heap_region_iterate(&cl);
1027   }
1028 }
1029 
1030 void G1CollectedHeap::abort_concurrent_cycle() {
1031   // Note: When we have a more flexible GC logging framework that
1032   // allows us to add optional attributes to a GC log record we
1033   // could consider timing and reporting how long we wait in the
1034   // following two methods.
1035   wait_while_free_regions_coming();
1036   // If we start the compaction before the CM threads finish
1037   // scanning the root regions we might trip them over as we'll
1038   // be moving objects / updating references. So let's wait until
1039   // they are done. By telling them to abort, they should complete
1040   // early.
1041   _cm->root_regions()->abort();
1042   _cm->root_regions()->wait_until_scan_finished();
1043   append_secondary_free_list_if_not_empty_with_lock();
1044 
1045   // Disable discovery and empty the discovered lists
1046   // for the CM ref processor.
1047   ref_processor_cm()->disable_discovery();
1048   ref_processor_cm()->abandon_partial_discovery();
1049   ref_processor_cm()->verify_no_references_recorded();
1050 
1051   // Abandon current iterations of concurrent marking and concurrent
1052   // refinement, if any are in progress.
1053   concurrent_mark()->abort();
1054 }
1055 
1056 void G1CollectedHeap::prepare_heap_for_full_collection() {
1057   // Make sure we'll choose a new allocation region afterwards.
1058   _allocator->release_mutator_alloc_region();
1059   _allocator->abandon_gc_alloc_regions();
1060   g1_rem_set()->cleanupHRRS();
1061 
1062   // We may have added regions to the current incremental collection
1063   // set between the last GC or pause and now. We need to clear the
1064   // incremental collection set and then start rebuilding it afresh
1065   // after this full GC.
1066   abandon_collection_set(collection_set());
1067 
1068   tear_down_region_sets(false /* free_list_only */);
1069   collector_state()->set_gcs_are_young(true);
1070 }
1071 
1072 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1073   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1074   assert(used() == recalculate_used(), "Should be equal");
1075   _verifier->verify_region_sets_optional();
1076   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1077   _verifier->check_bitmaps("Full GC Start");
1078 }
1079 
1080 void G1CollectedHeap::prepare_heap_for_mutators() {
1081   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1082   ClassLoaderDataGraph::purge();
1083   MetaspaceAux::verify_metrics();
1084 
1085   // Prepare heap for normal collections.
1086   assert(num_free_regions() == 0, "we should not have added any free regions");
1087   rebuild_region_sets(false /* free_list_only */);
1088   abort_refinement();
1089   resize_if_necessary_after_full_collection();
1090 
1091   // Rebuild the strong code root lists for each region
1092   rebuild_strong_code_roots();
1093 
1094   // Start a new incremental collection set for the next pause
1095   start_new_collection_set();
1096 
1097   _allocator->init_mutator_alloc_region();
1098 
1099   // Post collection state updates.
1100   MetaspaceGC::compute_new_size();
1101 }
1102 
1103 void G1CollectedHeap::abort_refinement() {
1104   if (_hot_card_cache->use_cache()) {
1105     _hot_card_cache->reset_hot_cache();
1106   }
1107 
1108   // Discard all remembered set updates.
1109   JavaThread::dirty_card_queue_set().abandon_logs();
1110   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1111 }
1112 
1113 void G1CollectedHeap::verify_after_full_collection() {
1114   check_gc_time_stamps();
1115   _hrm.verify_optional();
1116   _verifier->verify_region_sets_optional();
1117   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1118   // Clear the previous marking bitmap, if needed for bitmap verification.
1119   // Note we cannot do this when we clear the next marking bitmap in
1120   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1121   // objects marked during a full GC against the previous bitmap.
1122   // But we need to clear it before calling check_bitmaps below since
1123   // the full GC has compacted objects and updated TAMS but not updated
1124   // the prev bitmap.
1125   if (G1VerifyBitmaps) {
1126     GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1127     _cm->clear_prev_bitmap(workers());
1128   }
1129   _verifier->check_bitmaps("Full GC End");
1130 
1131   // At this point there should be no regions in the
1132   // entire heap tagged as young.
1133   assert(check_young_list_empty(), "young list should be empty at this point");
1134 
1135   // Note: since we've just done a full GC, concurrent
1136   // marking is no longer active. Therefore we need not
1137   // re-enable reference discovery for the CM ref processor.
1138   // That will be done at the start of the next marking cycle.
1139   // We also know that the STW processor should no longer
1140   // discover any new references.
1141   assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1142   assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1143   ref_processor_stw()->verify_no_references_recorded();
1144   ref_processor_cm()->verify_no_references_recorded();
1145 }
1146 
1147 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1148   // Post collection logging.
1149   // We should do this after we potentially resize the heap so
1150   // that all the COMMIT / UNCOMMIT events are generated before
1151   // the compaction events.
1152   print_hrm_post_compaction();
1153   heap_transition->print();
1154   print_heap_after_gc();
1155   print_heap_regions();
1156 #ifdef TRACESPINNING
1157   ParallelTaskTerminator::print_termination_counts();
1158 #endif
1159 }
1160 
1161 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1162                                          bool clear_all_soft_refs) {
1163   assert_at_safepoint(true /* should_be_vm_thread */);
1164 
1165   if (GCLocker::check_active_before_gc()) {
1166     // Full GC was not completed.
1167     return false;
1168   }
1169 
1170   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1171       collector_policy()->should_clear_all_soft_refs();
1172 
1173   G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1174   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1175 
1176   collector.prepare_collection();
1177   collector.collect();
1178   collector.complete_collection();
1179 
1180   // Full collection was successfully completed.
1181   return true;
1182 }
1183 
1184 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1185   // Currently, there is no facility in the do_full_collection(bool) API to notify
1186   // the caller that the collection did not succeed (e.g., because it was locked
1187   // out by the GC locker). So, right now, we'll ignore the return value.
1188   bool dummy = do_full_collection(true,                /* explicit_gc */
1189                                   clear_all_soft_refs);
1190 }
1191 
1192 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1193   // Capacity, free and used after the GC counted as full regions to
1194   // include the waste in the following calculations.
1195   const size_t capacity_after_gc = capacity();
1196   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1197 
1198   // This is enforced in arguments.cpp.
1199   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1200          "otherwise the code below doesn't make sense");
1201 
1202   // We don't have floating point command-line arguments
1203   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1204   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1205   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1206   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1207 
1208   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1209   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1210 
1211   // We have to be careful here as these two calculations can overflow
1212   // 32-bit size_t's.
1213   double used_after_gc_d = (double) used_after_gc;
1214   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1215   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1216 
1217   // Let's make sure that they are both under the max heap size, which
1218   // by default will make them fit into a size_t.
1219   double desired_capacity_upper_bound = (double) max_heap_size;
1220   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1221                                     desired_capacity_upper_bound);
1222   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1223                                     desired_capacity_upper_bound);
1224 
1225   // We can now safely turn them into size_t's.
1226   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1227   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1228 
1229   // This assert only makes sense here, before we adjust them
1230   // with respect to the min and max heap size.
1231   assert(minimum_desired_capacity <= maximum_desired_capacity,
1232          "minimum_desired_capacity = " SIZE_FORMAT ", "
1233          "maximum_desired_capacity = " SIZE_FORMAT,
1234          minimum_desired_capacity, maximum_desired_capacity);
1235 
1236   // Should not be greater than the heap max size. No need to adjust
1237   // it with respect to the heap min size as it's a lower bound (i.e.,
1238   // we'll try to make the capacity larger than it, not smaller).
1239   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1240   // Should not be less than the heap min size. No need to adjust it
1241   // with respect to the heap max size as it's an upper bound (i.e.,
1242   // we'll try to make the capacity smaller than it, not greater).
1243   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1244 
1245   if (capacity_after_gc < minimum_desired_capacity) {
1246     // Don't expand unless it's significant
1247     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1248 
1249     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1250                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1251                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1252                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1253 
1254     expand(expand_bytes, _workers);
1255 
1256     // No expansion, now see if we want to shrink
1257   } else if (capacity_after_gc > maximum_desired_capacity) {
1258     // Capacity too large, compute shrinking size
1259     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1260 
1261     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1262                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1263                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1264                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1265 
1266     shrink(shrink_bytes);
1267   }
1268 }
1269 
1270 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1271                                                             AllocationContext_t context,
1272                                                             bool do_gc,
1273                                                             bool clear_all_soft_refs,
1274                                                             bool expect_null_mutator_alloc_region,
1275                                                             bool* gc_succeeded) {
1276   *gc_succeeded = true;
1277   // Let's attempt the allocation first.
1278   HeapWord* result =
1279     attempt_allocation_at_safepoint(word_size,
1280                                     context,
1281                                     expect_null_mutator_alloc_region);
1282   if (result != NULL) {
1283     return result;
1284   }
1285 
1286   // In a G1 heap, we're supposed to keep allocation from failing by
1287   // incremental pauses.  Therefore, at least for now, we'll favor
1288   // expansion over collection.  (This might change in the future if we can
1289   // do something smarter than full collection to satisfy a failed alloc.)
1290   result = expand_and_allocate(word_size, context);
1291   if (result != NULL) {
1292     return result;
1293   }
1294 
1295   if (do_gc) {
1296     // Expansion didn't work, we'll try to do a Full GC.
1297     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1298                                        clear_all_soft_refs);
1299   }
1300 
1301   return NULL;
1302 }
1303 
1304 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1305                                                      AllocationContext_t context,
1306                                                      bool* succeeded) {
1307   assert_at_safepoint(true /* should_be_vm_thread */);
1308 
1309   // Attempts to allocate followed by Full GC.
1310   HeapWord* result =
1311     satisfy_failed_allocation_helper(word_size,
1312                                      context,
1313                                      true,  /* do_gc */
1314                                      false, /* clear_all_soft_refs */
1315                                      false, /* expect_null_mutator_alloc_region */
1316                                      succeeded);
1317 
1318   if (result != NULL || !*succeeded) {
1319     return result;
1320   }
1321 
1322   // Attempts to allocate followed by Full GC that will collect all soft references.
1323   result = satisfy_failed_allocation_helper(word_size,
1324                                             context,
1325                                             true, /* do_gc */
1326                                             true, /* clear_all_soft_refs */
1327                                             true, /* expect_null_mutator_alloc_region */
1328                                             succeeded);
1329 
1330   if (result != NULL || !*succeeded) {
1331     return result;
1332   }
1333 
1334   // Attempts to allocate, no GC
1335   result = satisfy_failed_allocation_helper(word_size,
1336                                             context,
1337                                             false, /* do_gc */
1338                                             false, /* clear_all_soft_refs */
1339                                             true,  /* expect_null_mutator_alloc_region */
1340                                             succeeded);
1341 
1342   if (result != NULL) {
1343     return result;
1344   }
1345 
1346   assert(!collector_policy()->should_clear_all_soft_refs(),
1347          "Flag should have been handled and cleared prior to this point");
1348 
1349   // What else?  We might try synchronous finalization later.  If the total
1350   // space available is large enough for the allocation, then a more
1351   // complete compaction phase than we've tried so far might be
1352   // appropriate.
1353   return NULL;
1354 }
1355 
1356 // Attempting to expand the heap sufficiently
1357 // to support an allocation of the given "word_size".  If
1358 // successful, perform the allocation and return the address of the
1359 // allocated block, or else "NULL".
1360 
1361 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1362   assert_at_safepoint(true /* should_be_vm_thread */);
1363 
1364   _verifier->verify_region_sets_optional();
1365 
1366   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1367   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1368                             word_size * HeapWordSize);
1369 
1370 
1371   if (expand(expand_bytes, _workers)) {
1372     _hrm.verify_optional();
1373     _verifier->verify_region_sets_optional();
1374     return attempt_allocation_at_safepoint(word_size,
1375                                            context,
1376                                            false /* expect_null_mutator_alloc_region */);
1377   }
1378   return NULL;
1379 }
1380 
1381 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1382   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1383   aligned_expand_bytes = align_up(aligned_expand_bytes,
1384                                        HeapRegion::GrainBytes);
1385 
1386   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1387                             expand_bytes, aligned_expand_bytes);
1388 
1389   if (is_maximal_no_gc()) {
1390     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1391     return false;
1392   }
1393 
1394   double expand_heap_start_time_sec = os::elapsedTime();
1395   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1396   assert(regions_to_expand > 0, "Must expand by at least one region");
1397 
1398   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1399   if (expand_time_ms != NULL) {
1400     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1401   }
1402 
1403   if (expanded_by > 0) {
1404     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1405     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1406     g1_policy()->record_new_heap_size(num_regions());
1407   } else {
1408     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1409 
1410     // The expansion of the virtual storage space was unsuccessful.
1411     // Let's see if it was because we ran out of swap.
1412     if (G1ExitOnExpansionFailure &&
1413         _hrm.available() >= regions_to_expand) {
1414       // We had head room...
1415       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1416     }
1417   }
1418   return regions_to_expand > 0;
1419 }
1420 
1421 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1422   size_t aligned_shrink_bytes =
1423     ReservedSpace::page_align_size_down(shrink_bytes);
1424   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1425                                          HeapRegion::GrainBytes);
1426   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1427 
1428   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1429   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1430 
1431 
1432   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",
1433                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1434   if (num_regions_removed > 0) {
1435     g1_policy()->record_new_heap_size(num_regions());
1436   } else {
1437     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1438   }
1439 }
1440 
1441 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1442   _verifier->verify_region_sets_optional();
1443 
1444   // We should only reach here at the end of a Full GC which means we
1445   // should not not be holding to any GC alloc regions. The method
1446   // below will make sure of that and do any remaining clean up.
1447   _allocator->abandon_gc_alloc_regions();
1448 
1449   // Instead of tearing down / rebuilding the free lists here, we
1450   // could instead use the remove_all_pending() method on free_list to
1451   // remove only the ones that we need to remove.
1452   tear_down_region_sets(true /* free_list_only */);
1453   shrink_helper(shrink_bytes);
1454   rebuild_region_sets(true /* free_list_only */);
1455 
1456   _hrm.verify_optional();
1457   _verifier->verify_region_sets_optional();
1458 }
1459 
1460 // Public methods.
1461 
1462 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1463   CollectedHeap(),
1464   _young_gen_sampling_thread(NULL),
1465   _collector_policy(collector_policy),
1466   _memory_manager("G1 Young Generation", "end of minor GC"),
1467   _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1468   _eden_pool(NULL),
1469   _survivor_pool(NULL),
1470   _old_pool(NULL),
1471   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1472   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1473   _g1_policy(create_g1_policy(_gc_timer_stw)),
1474   _collection_set(this, _g1_policy),
1475   _dirty_card_queue_set(false),
1476   _is_alive_closure_cm(this),
1477   _is_alive_closure_stw(this),
1478   _ref_processor_cm(NULL),
1479   _ref_processor_stw(NULL),
1480   _bot(NULL),
1481   _hot_card_cache(NULL),
1482   _g1_rem_set(NULL),
1483   _cr(NULL),
1484   _g1mm(NULL),
1485   _preserved_marks_set(true /* in_c_heap */),
1486   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1487   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1488   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1489   _humongous_reclaim_candidates(),
1490   _has_humongous_reclaim_candidates(false),
1491   _archive_allocator(NULL),
1492   _free_regions_coming(false),
1493   _gc_time_stamp(0),
1494   _summary_bytes_used(0),
1495   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1496   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1497   _expand_heap_after_alloc_failure(true),
1498   _old_marking_cycles_started(0),
1499   _old_marking_cycles_completed(0),
1500   _in_cset_fast_test() {
1501 
1502   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1503                           /* are_GC_task_threads */true,
1504                           /* are_ConcurrentGC_threads */false);
1505   _workers->initialize_workers();
1506   _verifier = new G1HeapVerifier(this);
1507 
1508   _allocator = G1Allocator::create_allocator(this);
1509 
1510   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1511 
1512   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1513 
1514   // Override the default _filler_array_max_size so that no humongous filler
1515   // objects are created.
1516   _filler_array_max_size = _humongous_object_threshold_in_words;
1517 
1518   uint n_queues = ParallelGCThreads;
1519   _task_queues = new RefToScanQueueSet(n_queues);
1520 
1521   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1522 
1523   for (uint i = 0; i < n_queues; i++) {
1524     RefToScanQueue* q = new RefToScanQueue();
1525     q->initialize();
1526     _task_queues->register_queue(i, q);
1527     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1528   }
1529 
1530   // Initialize the G1EvacuationFailureALot counters and flags.
1531   NOT_PRODUCT(reset_evacuation_should_fail();)
1532 
1533   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1534 }
1535 
1536 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1537                                                                  size_t size,
1538                                                                  size_t translation_factor) {
1539   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1540   // Allocate a new reserved space, preferring to use large pages.
1541   ReservedSpace rs(size, preferred_page_size);
1542   G1RegionToSpaceMapper* result  =
1543     G1RegionToSpaceMapper::create_mapper(rs,
1544                                          size,
1545                                          rs.alignment(),
1546                                          HeapRegion::GrainBytes,
1547                                          translation_factor,
1548                                          mtGC);
1549 
1550   os::trace_page_sizes_for_requested_size(description,
1551                                           size,
1552                                           preferred_page_size,
1553                                           rs.alignment(),
1554                                           rs.base(),
1555                                           rs.size());
1556 
1557   return result;
1558 }
1559 
1560 jint G1CollectedHeap::initialize_concurrent_refinement() {
1561   jint ecode = JNI_OK;
1562   _cr = G1ConcurrentRefine::create(&ecode);
1563   return ecode;
1564 }
1565 
1566 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1567   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1568   if (_young_gen_sampling_thread->osthread() == NULL) {
1569     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1570     return JNI_ENOMEM;
1571   }
1572   return JNI_OK;
1573 }
1574 
1575 jint G1CollectedHeap::initialize() {
1576   CollectedHeap::pre_initialize();
1577   os::enable_vtime();
1578 
1579   // Necessary to satisfy locking discipline assertions.
1580 
1581   MutexLocker x(Heap_lock);
1582 
1583   // While there are no constraints in the GC code that HeapWordSize
1584   // be any particular value, there are multiple other areas in the
1585   // system which believe this to be true (e.g. oop->object_size in some
1586   // cases incorrectly returns the size in wordSize units rather than
1587   // HeapWordSize).
1588   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1589 
1590   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1591   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1592   size_t heap_alignment = collector_policy()->heap_alignment();
1593 
1594   // Ensure that the sizes are properly aligned.
1595   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1596   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1597   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1598 
1599   // Reserve the maximum.
1600 
1601   // When compressed oops are enabled, the preferred heap base
1602   // is calculated by subtracting the requested size from the
1603   // 32Gb boundary and using the result as the base address for
1604   // heap reservation. If the requested size is not aligned to
1605   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1606   // into the ReservedHeapSpace constructor) then the actual
1607   // base of the reserved heap may end up differing from the
1608   // address that was requested (i.e. the preferred heap base).
1609   // If this happens then we could end up using a non-optimal
1610   // compressed oops mode.
1611 
1612   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1613                                                  heap_alignment);
1614 
1615   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1616 
1617   // Create the barrier set for the entire reserved region.
1618   G1SATBCardTableLoggingModRefBS* bs
1619     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1620   bs->initialize();
1621   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1622   set_barrier_set(bs);
1623 
1624   // Create the hot card cache.
1625   _hot_card_cache = new G1HotCardCache(this);
1626 
1627   // Carve out the G1 part of the heap.
1628   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1629   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1630   G1RegionToSpaceMapper* heap_storage =
1631     G1RegionToSpaceMapper::create_mapper(g1_rs,
1632                                          g1_rs.size(),
1633                                          page_size,
1634                                          HeapRegion::GrainBytes,
1635                                          1,
1636                                          mtJavaHeap);
1637   os::trace_page_sizes("Heap",
1638                        collector_policy()->min_heap_byte_size(),
1639                        max_byte_size,
1640                        page_size,
1641                        heap_rs.base(),
1642                        heap_rs.size());
1643   heap_storage->set_mapping_changed_listener(&_listener);
1644 
1645   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1646   G1RegionToSpaceMapper* bot_storage =
1647     create_aux_memory_mapper("Block Offset Table",
1648                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1649                              G1BlockOffsetTable::heap_map_factor());
1650 
1651   G1RegionToSpaceMapper* cardtable_storage =
1652     create_aux_memory_mapper("Card Table",
1653                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1654                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1655 
1656   G1RegionToSpaceMapper* card_counts_storage =
1657     create_aux_memory_mapper("Card Counts Table",
1658                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1659                              G1CardCounts::heap_map_factor());
1660 
1661   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1662   G1RegionToSpaceMapper* prev_bitmap_storage =
1663     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1664   G1RegionToSpaceMapper* next_bitmap_storage =
1665     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1666 
1667   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1668   g1_barrier_set()->initialize(cardtable_storage);
1669   // Do later initialization work for concurrent refinement.
1670   _hot_card_cache->initialize(card_counts_storage);
1671 
1672   // 6843694 - ensure that the maximum region index can fit
1673   // in the remembered set structures.
1674   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1675   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1676 
1677   // Also create a G1 rem set.
1678   _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1679   _g1_rem_set->initialize(max_capacity(), max_regions());
1680 
1681   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1682   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1683   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1684             "too many cards per region");
1685 
1686   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1687 
1688   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1689 
1690   {
1691     HeapWord* start = _hrm.reserved().start();
1692     HeapWord* end = _hrm.reserved().end();
1693     size_t granularity = HeapRegion::GrainBytes;
1694 
1695     _in_cset_fast_test.initialize(start, end, granularity);
1696     _humongous_reclaim_candidates.initialize(start, end, granularity);
1697   }
1698 
1699   // Create the G1ConcurrentMark data structure and thread.
1700   // (Must do this late, so that "max_regions" is defined.)
1701   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1702   if (_cm == NULL || !_cm->completed_initialization()) {
1703     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1704     return JNI_ENOMEM;
1705   }
1706   _cmThread = _cm->cm_thread();
1707 
1708   // Now expand into the initial heap size.
1709   if (!expand(init_byte_size, _workers)) {
1710     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1711     return JNI_ENOMEM;
1712   }
1713 
1714   // Perform any initialization actions delegated to the policy.
1715   g1_policy()->init(this, &_collection_set);
1716 
1717   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1718                                                SATB_Q_FL_lock,
1719                                                G1SATBProcessCompletedThreshold,
1720                                                Shared_SATB_Q_lock);
1721 
1722   jint ecode = initialize_concurrent_refinement();
1723   if (ecode != JNI_OK) {
1724     return ecode;
1725   }
1726 
1727   ecode = initialize_young_gen_sampling_thread();
1728   if (ecode != JNI_OK) {
1729     return ecode;
1730   }
1731 
1732   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1733                                                 DirtyCardQ_FL_lock,
1734                                                 (int)concurrent_refine()->yellow_zone(),
1735                                                 (int)concurrent_refine()->red_zone(),
1736                                                 Shared_DirtyCardQ_lock,
1737                                                 NULL,  // fl_owner
1738                                                 true); // init_free_ids
1739 
1740   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1741                                     DirtyCardQ_FL_lock,
1742                                     -1, // never trigger processing
1743                                     -1, // no limit on length
1744                                     Shared_DirtyCardQ_lock,
1745                                     &JavaThread::dirty_card_queue_set());
1746 
1747   // Here we allocate the dummy HeapRegion that is required by the
1748   // G1AllocRegion class.
1749   HeapRegion* dummy_region = _hrm.get_dummy_region();
1750 
1751   // We'll re-use the same region whether the alloc region will
1752   // require BOT updates or not and, if it doesn't, then a non-young
1753   // region will complain that it cannot support allocations without
1754   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1755   dummy_region->set_eden();
1756   // Make sure it's full.
1757   dummy_region->set_top(dummy_region->end());
1758   G1AllocRegion::setup(this, dummy_region);
1759 
1760   _allocator->init_mutator_alloc_region();
1761 
1762   // Do create of the monitoring and management support so that
1763   // values in the heap have been properly initialized.
1764   _g1mm = new G1MonitoringSupport(this);
1765 
1766   G1StringDedup::initialize();
1767 
1768   _preserved_marks_set.init(ParallelGCThreads);
1769 
1770   _collection_set.initialize(max_regions());
1771 
1772   return JNI_OK;
1773 }
1774 
1775 void G1CollectedHeap::initialize_serviceability() {
1776   _eden_pool = new G1EdenPool(this);
1777   _survivor_pool = new G1SurvivorPool(this);
1778   _old_pool = new G1OldGenPool(this);
1779 
1780   _full_gc_memory_manager.add_pool(_eden_pool);
1781   _full_gc_memory_manager.add_pool(_survivor_pool);
1782   _full_gc_memory_manager.add_pool(_old_pool);
1783 
1784   _memory_manager.add_pool(_eden_pool);
1785   _memory_manager.add_pool(_survivor_pool);
1786 
1787 }
1788 
1789 void G1CollectedHeap::stop() {
1790   // Stop all concurrent threads. We do this to make sure these threads
1791   // do not continue to execute and access resources (e.g. logging)
1792   // that are destroyed during shutdown.
1793   _cr->stop();
1794   _young_gen_sampling_thread->stop();
1795   _cmThread->stop();
1796   if (G1StringDedup::is_enabled()) {
1797     G1StringDedup::stop();
1798   }
1799 }
1800 
1801 void G1CollectedHeap::safepoint_synchronize_begin() {
1802   SuspendibleThreadSet::synchronize();
1803 }
1804 
1805 void G1CollectedHeap::safepoint_synchronize_end() {
1806   SuspendibleThreadSet::desynchronize();
1807 }
1808 
1809 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1810   return HeapRegion::max_region_size();
1811 }
1812 
1813 void G1CollectedHeap::post_initialize() {
1814   CollectedHeap::post_initialize();
1815   ref_processing_init();
1816 }
1817 
1818 void G1CollectedHeap::ref_processing_init() {
1819   // Reference processing in G1 currently works as follows:
1820   //
1821   // * There are two reference processor instances. One is
1822   //   used to record and process discovered references
1823   //   during concurrent marking; the other is used to
1824   //   record and process references during STW pauses
1825   //   (both full and incremental).
1826   // * Both ref processors need to 'span' the entire heap as
1827   //   the regions in the collection set may be dotted around.
1828   //
1829   // * For the concurrent marking ref processor:
1830   //   * Reference discovery is enabled at initial marking.
1831   //   * Reference discovery is disabled and the discovered
1832   //     references processed etc during remarking.
1833   //   * Reference discovery is MT (see below).
1834   //   * Reference discovery requires a barrier (see below).
1835   //   * Reference processing may or may not be MT
1836   //     (depending on the value of ParallelRefProcEnabled
1837   //     and ParallelGCThreads).
1838   //   * A full GC disables reference discovery by the CM
1839   //     ref processor and abandons any entries on it's
1840   //     discovered lists.
1841   //
1842   // * For the STW processor:
1843   //   * Non MT discovery is enabled at the start of a full GC.
1844   //   * Processing and enqueueing during a full GC is non-MT.
1845   //   * During a full GC, references are processed after marking.
1846   //
1847   //   * Discovery (may or may not be MT) is enabled at the start
1848   //     of an incremental evacuation pause.
1849   //   * References are processed near the end of a STW evacuation pause.
1850   //   * For both types of GC:
1851   //     * Discovery is atomic - i.e. not concurrent.
1852   //     * Reference discovery will not need a barrier.
1853 
1854   MemRegion mr = reserved_region();
1855 
1856   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1857 
1858   // Concurrent Mark ref processor
1859   _ref_processor_cm =
1860     new ReferenceProcessor(mr,    // span
1861                            mt_processing,
1862                                 // mt processing
1863                            ParallelGCThreads,
1864                                 // degree of mt processing
1865                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1866                                 // mt discovery
1867                            MAX2(ParallelGCThreads, ConcGCThreads),
1868                                 // degree of mt discovery
1869                            false,
1870                                 // Reference discovery is not atomic
1871                            &_is_alive_closure_cm);
1872                                 // is alive closure
1873                                 // (for efficiency/performance)
1874 
1875   // STW ref processor
1876   _ref_processor_stw =
1877     new ReferenceProcessor(mr,    // span
1878                            mt_processing,
1879                                 // mt processing
1880                            ParallelGCThreads,
1881                                 // degree of mt processing
1882                            (ParallelGCThreads > 1),
1883                                 // mt discovery
1884                            ParallelGCThreads,
1885                                 // degree of mt discovery
1886                            true,
1887                                 // Reference discovery is atomic
1888                            &_is_alive_closure_stw);
1889                                 // is alive closure
1890                                 // (for efficiency/performance)
1891 }
1892 
1893 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1894   return _collector_policy;
1895 }
1896 
1897 size_t G1CollectedHeap::capacity() const {
1898   return _hrm.length() * HeapRegion::GrainBytes;
1899 }
1900 
1901 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1902   return _hrm.total_free_bytes();
1903 }
1904 
1905 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1906   hr->reset_gc_time_stamp();
1907 }
1908 
1909 #ifndef PRODUCT
1910 
1911 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1912 private:
1913   unsigned _gc_time_stamp;
1914   bool _failures;
1915 
1916 public:
1917   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1918     _gc_time_stamp(gc_time_stamp), _failures(false) { }
1919 
1920   virtual bool doHeapRegion(HeapRegion* hr) {
1921     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1922     if (_gc_time_stamp != region_gc_time_stamp) {
1923       log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1924                             region_gc_time_stamp, _gc_time_stamp);
1925       _failures = true;
1926     }
1927     return false;
1928   }
1929 
1930   bool failures() { return _failures; }
1931 };
1932 
1933 void G1CollectedHeap::check_gc_time_stamps() {
1934   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1935   heap_region_iterate(&cl);
1936   guarantee(!cl.failures(), "all GC time stamps should have been reset");
1937 }
1938 #endif // PRODUCT
1939 
1940 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1941   _hot_card_cache->drain(cl, worker_i);
1942 }
1943 
1944 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1945   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1946   size_t n_completed_buffers = 0;
1947   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1948     n_completed_buffers++;
1949   }
1950   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1951   dcqs.clear_n_completed_buffers();
1952   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1953 }
1954 
1955 // Computes the sum of the storage used by the various regions.
1956 size_t G1CollectedHeap::used() const {
1957   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1958   if (_archive_allocator != NULL) {
1959     result += _archive_allocator->used();
1960   }
1961   return result;
1962 }
1963 
1964 size_t G1CollectedHeap::used_unlocked() const {
1965   return _summary_bytes_used;
1966 }
1967 
1968 class SumUsedClosure: public HeapRegionClosure {
1969   size_t _used;
1970 public:
1971   SumUsedClosure() : _used(0) {}
1972   bool doHeapRegion(HeapRegion* r) {
1973     _used += r->used();
1974     return false;
1975   }
1976   size_t result() { return _used; }
1977 };
1978 
1979 size_t G1CollectedHeap::recalculate_used() const {
1980   double recalculate_used_start = os::elapsedTime();
1981 
1982   SumUsedClosure blk;
1983   heap_region_iterate(&blk);
1984 
1985   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1986   return blk.result();
1987 }
1988 
1989 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1990   switch (cause) {
1991     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1992     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1993     case GCCause::_update_allocation_context_stats_inc: return true;
1994     case GCCause::_wb_conc_mark:                        return true;
1995     default :                                           return false;
1996   }
1997 }
1998 
1999 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2000   switch (cause) {
2001     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2002     case GCCause::_g1_humongous_allocation: return true;
2003     default:                                return is_user_requested_concurrent_full_gc(cause);
2004   }
2005 }
2006 
2007 #ifndef PRODUCT
2008 void G1CollectedHeap::allocate_dummy_regions() {
2009   // Let's fill up most of the region
2010   size_t word_size = HeapRegion::GrainWords - 1024;
2011   // And as a result the region we'll allocate will be humongous.
2012   guarantee(is_humongous(word_size), "sanity");
2013 
2014   // _filler_array_max_size is set to humongous object threshold
2015   // but temporarily change it to use CollectedHeap::fill_with_object().
2016   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2017 
2018   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2019     // Let's use the existing mechanism for the allocation
2020     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2021                                                  AllocationContext::system());
2022     if (dummy_obj != NULL) {
2023       MemRegion mr(dummy_obj, word_size);
2024       CollectedHeap::fill_with_object(mr);
2025     } else {
2026       // If we can't allocate once, we probably cannot allocate
2027       // again. Let's get out of the loop.
2028       break;
2029     }
2030   }
2031 }
2032 #endif // !PRODUCT
2033 
2034 void G1CollectedHeap::increment_old_marking_cycles_started() {
2035   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2036          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2037          "Wrong marking cycle count (started: %d, completed: %d)",
2038          _old_marking_cycles_started, _old_marking_cycles_completed);
2039 
2040   _old_marking_cycles_started++;
2041 }
2042 
2043 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2044   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2045 
2046   // We assume that if concurrent == true, then the caller is a
2047   // concurrent thread that was joined the Suspendible Thread
2048   // Set. If there's ever a cheap way to check this, we should add an
2049   // assert here.
2050 
2051   // Given that this method is called at the end of a Full GC or of a
2052   // concurrent cycle, and those can be nested (i.e., a Full GC can
2053   // interrupt a concurrent cycle), the number of full collections
2054   // completed should be either one (in the case where there was no
2055   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2056   // behind the number of full collections started.
2057 
2058   // This is the case for the inner caller, i.e. a Full GC.
2059   assert(concurrent ||
2060          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2061          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2062          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2063          "is inconsistent with _old_marking_cycles_completed = %u",
2064          _old_marking_cycles_started, _old_marking_cycles_completed);
2065 
2066   // This is the case for the outer caller, i.e. the concurrent cycle.
2067   assert(!concurrent ||
2068          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2069          "for outer caller (concurrent cycle): "
2070          "_old_marking_cycles_started = %u "
2071          "is inconsistent with _old_marking_cycles_completed = %u",
2072          _old_marking_cycles_started, _old_marking_cycles_completed);
2073 
2074   _old_marking_cycles_completed += 1;
2075 
2076   // We need to clear the "in_progress" flag in the CM thread before
2077   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2078   // is set) so that if a waiter requests another System.gc() it doesn't
2079   // incorrectly see that a marking cycle is still in progress.
2080   if (concurrent) {
2081     _cmThread->set_idle();
2082   }
2083 
2084   // This notify_all() will ensure that a thread that called
2085   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2086   // and it's waiting for a full GC to finish will be woken up. It is
2087   // waiting in VM_G1CollectForAllocation::doit_epilogue().
2088   FullGCCount_lock->notify_all();
2089 }
2090 
2091 void G1CollectedHeap::collect(GCCause::Cause cause) {
2092   assert_heap_not_locked();
2093 
2094   uint gc_count_before;
2095   uint old_marking_count_before;
2096   uint full_gc_count_before;
2097   bool retry_gc;
2098 
2099   do {
2100     retry_gc = false;
2101 
2102     {
2103       MutexLocker ml(Heap_lock);
2104 
2105       // Read the GC count while holding the Heap_lock
2106       gc_count_before = total_collections();
2107       full_gc_count_before = total_full_collections();
2108       old_marking_count_before = _old_marking_cycles_started;
2109     }
2110 
2111     if (should_do_concurrent_full_gc(cause)) {
2112       // Schedule an initial-mark evacuation pause that will start a
2113       // concurrent cycle. We're setting word_size to 0 which means that
2114       // we are not requesting a post-GC allocation.
2115       VM_G1CollectForAllocation op(0,     /* word_size */
2116                                    gc_count_before,
2117                                    cause,
2118                                    true,  /* should_initiate_conc_mark */
2119                                    g1_policy()->max_pause_time_ms(),
2120                                    AllocationContext::current());
2121       VMThread::execute(&op);
2122       if (!op.pause_succeeded()) {
2123         if (old_marking_count_before == _old_marking_cycles_started) {
2124           retry_gc = op.should_retry_gc();
2125         } else {
2126           // A Full GC happened while we were trying to schedule the
2127           // initial-mark GC. No point in starting a new cycle given
2128           // that the whole heap was collected anyway.
2129         }
2130 
2131         if (retry_gc) {
2132           if (GCLocker::is_active_and_needs_gc()) {
2133             GCLocker::stall_until_clear();
2134           }
2135         }
2136       }
2137     } else {
2138       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2139           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2140 
2141         // Schedule a standard evacuation pause. We're setting word_size
2142         // to 0 which means that we are not requesting a post-GC allocation.
2143         VM_G1CollectForAllocation op(0,     /* word_size */
2144                                      gc_count_before,
2145                                      cause,
2146                                      false, /* should_initiate_conc_mark */
2147                                      g1_policy()->max_pause_time_ms(),
2148                                      AllocationContext::current());
2149         VMThread::execute(&op);
2150       } else {
2151         // Schedule a Full GC.
2152         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2153         VMThread::execute(&op);
2154       }
2155     }
2156   } while (retry_gc);
2157 }
2158 
2159 bool G1CollectedHeap::is_in(const void* p) const {
2160   if (_hrm.reserved().contains(p)) {
2161     // Given that we know that p is in the reserved space,
2162     // heap_region_containing() should successfully
2163     // return the containing region.
2164     HeapRegion* hr = heap_region_containing(p);
2165     return hr->is_in(p);
2166   } else {
2167     return false;
2168   }
2169 }
2170 
2171 #ifdef ASSERT
2172 bool G1CollectedHeap::is_in_exact(const void* p) const {
2173   bool contains = reserved_region().contains(p);
2174   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2175   if (contains && available) {
2176     return true;
2177   } else {
2178     return false;
2179   }
2180 }
2181 #endif
2182 
2183 // Iteration functions.
2184 
2185 // Iterates an ObjectClosure over all objects within a HeapRegion.
2186 
2187 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2188   ObjectClosure* _cl;
2189 public:
2190   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2191   bool doHeapRegion(HeapRegion* r) {
2192     if (!r->is_continues_humongous()) {
2193       r->object_iterate(_cl);
2194     }
2195     return false;
2196   }
2197 };
2198 
2199 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2200   IterateObjectClosureRegionClosure blk(cl);
2201   heap_region_iterate(&blk);
2202 }
2203 
2204 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2205   _hrm.iterate(cl);
2206 }
2207 
2208 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2209                                                                  HeapRegionClaimer *hrclaimer,
2210                                                                  uint worker_id) const {
2211   _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2212 }
2213 
2214 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2215                                                          HeapRegionClaimer *hrclaimer) const {
2216   _hrm.par_iterate(cl, hrclaimer, 0);
2217 }
2218 
2219 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2220   _collection_set.iterate(cl);
2221 }
2222 
2223 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2224   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2225 }
2226 
2227 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2228   HeapRegion* hr = heap_region_containing(addr);
2229   return hr->block_start(addr);
2230 }
2231 
2232 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2233   HeapRegion* hr = heap_region_containing(addr);
2234   return hr->block_size(addr);
2235 }
2236 
2237 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2238   HeapRegion* hr = heap_region_containing(addr);
2239   return hr->block_is_obj(addr);
2240 }
2241 
2242 bool G1CollectedHeap::supports_tlab_allocation() const {
2243   return true;
2244 }
2245 
2246 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2247   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2248 }
2249 
2250 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2251   return _eden.length() * HeapRegion::GrainBytes;
2252 }
2253 
2254 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2255 // must be equal to the humongous object limit.
2256 size_t G1CollectedHeap::max_tlab_size() const {
2257   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2258 }
2259 
2260 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2261   AllocationContext_t context = AllocationContext::current();
2262   return _allocator->unsafe_max_tlab_alloc(context);
2263 }
2264 
2265 size_t G1CollectedHeap::max_capacity() const {
2266   return _hrm.reserved().byte_size();
2267 }
2268 
2269 jlong G1CollectedHeap::millis_since_last_gc() {
2270   // See the notes in GenCollectedHeap::millis_since_last_gc()
2271   // for more information about the implementation.
2272   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2273     _g1_policy->collection_pause_end_millis();
2274   if (ret_val < 0) {
2275     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2276       ". returning zero instead.", ret_val);
2277     return 0;
2278   }
2279   return ret_val;
2280 }
2281 
2282 void G1CollectedHeap::prepare_for_verify() {
2283   _verifier->prepare_for_verify();
2284 }
2285 
2286 void G1CollectedHeap::verify(VerifyOption vo) {
2287   _verifier->verify(vo);
2288 }
2289 
2290 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2291   return true;
2292 }
2293 
2294 const char* const* G1CollectedHeap::concurrent_phases() const {
2295   return _cmThread->concurrent_phases();
2296 }
2297 
2298 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2299   return _cmThread->request_concurrent_phase(phase);
2300 }
2301 
2302 class PrintRegionClosure: public HeapRegionClosure {
2303   outputStream* _st;
2304 public:
2305   PrintRegionClosure(outputStream* st) : _st(st) {}
2306   bool doHeapRegion(HeapRegion* r) {
2307     r->print_on(_st);
2308     return false;
2309   }
2310 };
2311 
2312 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2313                                        const HeapRegion* hr,
2314                                        const VerifyOption vo) const {
2315   switch (vo) {
2316   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2317   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2318   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2319   default:                            ShouldNotReachHere();
2320   }
2321   return false; // keep some compilers happy
2322 }
2323 
2324 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2325                                        const VerifyOption vo) const {
2326   switch (vo) {
2327   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2328   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2329   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2330   default:                            ShouldNotReachHere();
2331   }
2332   return false; // keep some compilers happy
2333 }
2334 
2335 void G1CollectedHeap::print_heap_regions() const {
2336   LogTarget(Trace, gc, heap, region) lt;
2337   if (lt.is_enabled()) {
2338     LogStream ls(lt);
2339     print_regions_on(&ls);
2340   }
2341 }
2342 
2343 void G1CollectedHeap::print_on(outputStream* st) const {
2344   st->print(" %-20s", "garbage-first heap");
2345   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2346             capacity()/K, used_unlocked()/K);
2347   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2348             p2i(_hrm.reserved().start()),
2349             p2i(_hrm.reserved().end()));
2350   st->cr();
2351   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2352   uint young_regions = young_regions_count();
2353   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2354             (size_t) young_regions * HeapRegion::GrainBytes / K);
2355   uint survivor_regions = survivor_regions_count();
2356   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2357             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2358   st->cr();
2359   MetaspaceAux::print_on(st);
2360 }
2361 
2362 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2363   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2364                "HS=humongous(starts), HC=humongous(continues), "
2365                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2366                "AC=allocation context, "
2367                "TAMS=top-at-mark-start (previous, next)");
2368   PrintRegionClosure blk(st);
2369   heap_region_iterate(&blk);
2370 }
2371 
2372 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2373   print_on(st);
2374 
2375   // Print the per-region information.
2376   print_regions_on(st);
2377 }
2378 
2379 void G1CollectedHeap::print_on_error(outputStream* st) const {
2380   this->CollectedHeap::print_on_error(st);
2381 
2382   if (_cm != NULL) {
2383     st->cr();
2384     _cm->print_on_error(st);
2385   }
2386 }
2387 
2388 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2389   workers()->print_worker_threads_on(st);
2390   _cmThread->print_on(st);
2391   st->cr();
2392   _cm->print_worker_threads_on(st);
2393   _cr->print_threads_on(st);
2394   _young_gen_sampling_thread->print_on(st);
2395   if (G1StringDedup::is_enabled()) {
2396     G1StringDedup::print_worker_threads_on(st);
2397   }
2398 }
2399 
2400 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2401   workers()->threads_do(tc);
2402   tc->do_thread(_cmThread);
2403   _cm->threads_do(tc);
2404   _cr->threads_do(tc);
2405   tc->do_thread(_young_gen_sampling_thread);
2406   if (G1StringDedup::is_enabled()) {
2407     G1StringDedup::threads_do(tc);
2408   }
2409 }
2410 
2411 void G1CollectedHeap::print_tracing_info() const {
2412   g1_rem_set()->print_summary_info();
2413   concurrent_mark()->print_summary_info();
2414 }
2415 
2416 #ifndef PRODUCT
2417 // Helpful for debugging RSet issues.
2418 
2419 class PrintRSetsClosure : public HeapRegionClosure {
2420 private:
2421   const char* _msg;
2422   size_t _occupied_sum;
2423 
2424 public:
2425   bool doHeapRegion(HeapRegion* r) {
2426     HeapRegionRemSet* hrrs = r->rem_set();
2427     size_t occupied = hrrs->occupied();
2428     _occupied_sum += occupied;
2429 
2430     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2431     if (occupied == 0) {
2432       tty->print_cr("  RSet is empty");
2433     } else {
2434       hrrs->print();
2435     }
2436     tty->print_cr("----------");
2437     return false;
2438   }
2439 
2440   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2441     tty->cr();
2442     tty->print_cr("========================================");
2443     tty->print_cr("%s", msg);
2444     tty->cr();
2445   }
2446 
2447   ~PrintRSetsClosure() {
2448     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2449     tty->print_cr("========================================");
2450     tty->cr();
2451   }
2452 };
2453 
2454 void G1CollectedHeap::print_cset_rsets() {
2455   PrintRSetsClosure cl("Printing CSet RSets");
2456   collection_set_iterate(&cl);
2457 }
2458 
2459 void G1CollectedHeap::print_all_rsets() {
2460   PrintRSetsClosure cl("Printing All RSets");;
2461   heap_region_iterate(&cl);
2462 }
2463 #endif // PRODUCT
2464 
2465 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2466 
2467   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2468   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2469   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2470 
2471   size_t eden_capacity_bytes =
2472     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2473 
2474   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2475   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2476                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2477 }
2478 
2479 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2480   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2481                        stats->unused(), stats->used(), stats->region_end_waste(),
2482                        stats->regions_filled(), stats->direct_allocated(),
2483                        stats->failure_used(), stats->failure_waste());
2484 }
2485 
2486 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2487   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2488   gc_tracer->report_gc_heap_summary(when, heap_summary);
2489 
2490   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2491   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2492 }
2493 
2494 G1CollectedHeap* G1CollectedHeap::heap() {
2495   CollectedHeap* heap = Universe::heap();
2496   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2497   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2498   return (G1CollectedHeap*)heap;
2499 }
2500 
2501 void G1CollectedHeap::gc_prologue(bool full) {
2502   // always_do_update_barrier = false;
2503   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2504 
2505   // This summary needs to be printed before incrementing total collections.
2506   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2507 
2508   // Update common counters.
2509   increment_total_collections(full /* full gc */);
2510   if (full) {
2511     increment_old_marking_cycles_started();
2512     reset_gc_time_stamp();
2513   } else {
2514     increment_gc_time_stamp();
2515   }
2516 
2517   // Fill TLAB's and such
2518   double start = os::elapsedTime();
2519   accumulate_statistics_all_tlabs();
2520   ensure_parsability(true);
2521   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2522 }
2523 
2524 void G1CollectedHeap::gc_epilogue(bool full) {
2525   // Update common counters.
2526   if (full) {
2527     // Update the number of full collections that have been completed.
2528     increment_old_marking_cycles_completed(false /* concurrent */);
2529   }
2530 
2531   // We are at the end of the GC. Total collections has already been increased.
2532   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2533 
2534   // FIXME: what is this about?
2535   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2536   // is set.
2537 #if COMPILER2_OR_JVMCI
2538   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2539 #endif
2540   // always_do_update_barrier = true;
2541 
2542   double start = os::elapsedTime();
2543   resize_all_tlabs();
2544   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2545 
2546   allocation_context_stats().update(full);
2547 
2548   MemoryService::track_memory_usage();
2549   // We have just completed a GC. Update the soft reference
2550   // policy with the new heap occupancy
2551   Universe::update_heap_info_at_gc();
2552 }
2553 
2554 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2555                                                uint gc_count_before,
2556                                                bool* succeeded,
2557                                                GCCause::Cause gc_cause) {
2558   assert_heap_not_locked_and_not_at_safepoint();
2559   VM_G1CollectForAllocation op(word_size,
2560                                gc_count_before,
2561                                gc_cause,
2562                                false, /* should_initiate_conc_mark */
2563                                g1_policy()->max_pause_time_ms(),
2564                                AllocationContext::current());
2565   VMThread::execute(&op);
2566 
2567   HeapWord* result = op.result();
2568   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2569   assert(result == NULL || ret_succeeded,
2570          "the result should be NULL if the VM did not succeed");
2571   *succeeded = ret_succeeded;
2572 
2573   assert_heap_not_locked();
2574   return result;
2575 }
2576 
2577 void
2578 G1CollectedHeap::doConcurrentMark() {
2579   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2580   if (!_cmThread->in_progress()) {
2581     _cmThread->set_started();
2582     CGC_lock->notify();
2583   }
2584 }
2585 
2586 size_t G1CollectedHeap::pending_card_num() {
2587   size_t extra_cards = 0;
2588   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2589     DirtyCardQueue& dcq = curr->dirty_card_queue();
2590     extra_cards += dcq.size();
2591   }
2592   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2593   size_t buffer_size = dcqs.buffer_size();
2594   size_t buffer_num = dcqs.completed_buffers_num();
2595 
2596   return buffer_size * buffer_num + extra_cards;
2597 }
2598 
2599 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2600  private:
2601   size_t _total_humongous;
2602   size_t _candidate_humongous;
2603 
2604   DirtyCardQueue _dcq;
2605 
2606   // We don't nominate objects with many remembered set entries, on
2607   // the assumption that such objects are likely still live.
2608   bool is_remset_small(HeapRegion* region) const {
2609     HeapRegionRemSet* const rset = region->rem_set();
2610     return G1EagerReclaimHumongousObjectsWithStaleRefs
2611       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2612       : rset->is_empty();
2613   }
2614 
2615   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2616     assert(region->is_starts_humongous(), "Must start a humongous object");
2617 
2618     oop obj = oop(region->bottom());
2619 
2620     // Dead objects cannot be eager reclaim candidates. Due to class
2621     // unloading it is unsafe to query their classes so we return early.
2622     if (heap->is_obj_dead(obj, region)) {
2623       return false;
2624     }
2625 
2626     // Candidate selection must satisfy the following constraints
2627     // while concurrent marking is in progress:
2628     //
2629     // * In order to maintain SATB invariants, an object must not be
2630     // reclaimed if it was allocated before the start of marking and
2631     // has not had its references scanned.  Such an object must have
2632     // its references (including type metadata) scanned to ensure no
2633     // live objects are missed by the marking process.  Objects
2634     // allocated after the start of concurrent marking don't need to
2635     // be scanned.
2636     //
2637     // * An object must not be reclaimed if it is on the concurrent
2638     // mark stack.  Objects allocated after the start of concurrent
2639     // marking are never pushed on the mark stack.
2640     //
2641     // Nominating only objects allocated after the start of concurrent
2642     // marking is sufficient to meet both constraints.  This may miss
2643     // some objects that satisfy the constraints, but the marking data
2644     // structures don't support efficiently performing the needed
2645     // additional tests or scrubbing of the mark stack.
2646     //
2647     // However, we presently only nominate is_typeArray() objects.
2648     // A humongous object containing references induces remembered
2649     // set entries on other regions.  In order to reclaim such an
2650     // object, those remembered sets would need to be cleaned up.
2651     //
2652     // We also treat is_typeArray() objects specially, allowing them
2653     // to be reclaimed even if allocated before the start of
2654     // concurrent mark.  For this we rely on mark stack insertion to
2655     // exclude is_typeArray() objects, preventing reclaiming an object
2656     // that is in the mark stack.  We also rely on the metadata for
2657     // such objects to be built-in and so ensured to be kept live.
2658     // Frequent allocation and drop of large binary blobs is an
2659     // important use case for eager reclaim, and this special handling
2660     // may reduce needed headroom.
2661 
2662     return obj->is_typeArray() && is_remset_small(region);
2663   }
2664 
2665  public:
2666   RegisterHumongousWithInCSetFastTestClosure()
2667   : _total_humongous(0),
2668     _candidate_humongous(0),
2669     _dcq(&JavaThread::dirty_card_queue_set()) {
2670   }
2671 
2672   virtual bool doHeapRegion(HeapRegion* r) {
2673     if (!r->is_starts_humongous()) {
2674       return false;
2675     }
2676     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2677 
2678     bool is_candidate = humongous_region_is_candidate(g1h, r);
2679     uint rindex = r->hrm_index();
2680     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2681     if (is_candidate) {
2682       _candidate_humongous++;
2683       g1h->register_humongous_region_with_cset(rindex);
2684       // Is_candidate already filters out humongous object with large remembered sets.
2685       // If we have a humongous object with a few remembered sets, we simply flush these
2686       // remembered set entries into the DCQS. That will result in automatic
2687       // re-evaluation of their remembered set entries during the following evacuation
2688       // phase.
2689       if (!r->rem_set()->is_empty()) {
2690         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2691                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2692         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2693         HeapRegionRemSetIterator hrrs(r->rem_set());
2694         size_t card_index;
2695         while (hrrs.has_next(card_index)) {
2696           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2697           // The remembered set might contain references to already freed
2698           // regions. Filter out such entries to avoid failing card table
2699           // verification.
2700           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2701             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2702               *card_ptr = CardTableModRefBS::dirty_card_val();
2703               _dcq.enqueue(card_ptr);
2704             }
2705           }
2706         }
2707         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2708                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2709                hrrs.n_yielded(), r->rem_set()->occupied());
2710         r->rem_set()->clear_locked();
2711       }
2712       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2713     }
2714     _total_humongous++;
2715 
2716     return false;
2717   }
2718 
2719   size_t total_humongous() const { return _total_humongous; }
2720   size_t candidate_humongous() const { return _candidate_humongous; }
2721 
2722   void flush_rem_set_entries() { _dcq.flush(); }
2723 };
2724 
2725 void G1CollectedHeap::register_humongous_regions_with_cset() {
2726   if (!G1EagerReclaimHumongousObjects) {
2727     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2728     return;
2729   }
2730   double time = os::elapsed_counter();
2731 
2732   // Collect reclaim candidate information and register candidates with cset.
2733   RegisterHumongousWithInCSetFastTestClosure cl;
2734   heap_region_iterate(&cl);
2735 
2736   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2737   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2738                                                                   cl.total_humongous(),
2739                                                                   cl.candidate_humongous());
2740   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2741 
2742   // Finally flush all remembered set entries to re-check into the global DCQS.
2743   cl.flush_rem_set_entries();
2744 }
2745 
2746 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2747   public:
2748     bool doHeapRegion(HeapRegion* hr) {
2749       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2750         hr->verify_rem_set();
2751       }
2752       return false;
2753     }
2754 };
2755 
2756 uint G1CollectedHeap::num_task_queues() const {
2757   return _task_queues->size();
2758 }
2759 
2760 #if TASKQUEUE_STATS
2761 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2762   st->print_raw_cr("GC Task Stats");
2763   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2764   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2765 }
2766 
2767 void G1CollectedHeap::print_taskqueue_stats() const {
2768   if (!log_is_enabled(Trace, gc, task, stats)) {
2769     return;
2770   }
2771   Log(gc, task, stats) log;
2772   ResourceMark rm;
2773   LogStream ls(log.trace());
2774   outputStream* st = &ls;
2775 
2776   print_taskqueue_stats_hdr(st);
2777 
2778   TaskQueueStats totals;
2779   const uint n = num_task_queues();
2780   for (uint i = 0; i < n; ++i) {
2781     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2782     totals += task_queue(i)->stats;
2783   }
2784   st->print_raw("tot "); totals.print(st); st->cr();
2785 
2786   DEBUG_ONLY(totals.verify());
2787 }
2788 
2789 void G1CollectedHeap::reset_taskqueue_stats() {
2790   const uint n = num_task_queues();
2791   for (uint i = 0; i < n; ++i) {
2792     task_queue(i)->stats.reset();
2793   }
2794 }
2795 #endif // TASKQUEUE_STATS
2796 
2797 void G1CollectedHeap::wait_for_root_region_scanning() {
2798   double scan_wait_start = os::elapsedTime();
2799   // We have to wait until the CM threads finish scanning the
2800   // root regions as it's the only way to ensure that all the
2801   // objects on them have been correctly scanned before we start
2802   // moving them during the GC.
2803   bool waited = _cm->root_regions()->wait_until_scan_finished();
2804   double wait_time_ms = 0.0;
2805   if (waited) {
2806     double scan_wait_end = os::elapsedTime();
2807     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2808   }
2809   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2810 }
2811 
2812 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2813 private:
2814   G1HRPrinter* _hr_printer;
2815 public:
2816   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2817 
2818   virtual bool doHeapRegion(HeapRegion* r) {
2819     _hr_printer->cset(r);
2820     return false;
2821   }
2822 };
2823 
2824 void G1CollectedHeap::start_new_collection_set() {
2825   collection_set()->start_incremental_building();
2826 
2827   clear_cset_fast_test();
2828 
2829   guarantee(_eden.length() == 0, "eden should have been cleared");
2830   g1_policy()->transfer_survivors_to_cset(survivor());
2831 }
2832 
2833 bool
2834 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2835   assert_at_safepoint(true /* should_be_vm_thread */);
2836   guarantee(!is_gc_active(), "collection is not reentrant");
2837 
2838   if (GCLocker::check_active_before_gc()) {
2839     return false;
2840   }
2841 
2842   _gc_timer_stw->register_gc_start();
2843 
2844   GCIdMark gc_id_mark;
2845   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2846 
2847   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2848   ResourceMark rm;
2849 
2850   g1_policy()->note_gc_start();
2851 
2852   wait_for_root_region_scanning();
2853 
2854   print_heap_before_gc();
2855   print_heap_regions();
2856   trace_heap_before_gc(_gc_tracer_stw);
2857 
2858   _verifier->verify_region_sets_optional();
2859   _verifier->verify_dirty_young_regions();
2860 
2861   // We should not be doing initial mark unless the conc mark thread is running
2862   if (!_cmThread->should_terminate()) {
2863     // This call will decide whether this pause is an initial-mark
2864     // pause. If it is, during_initial_mark_pause() will return true
2865     // for the duration of this pause.
2866     g1_policy()->decide_on_conc_mark_initiation();
2867   }
2868 
2869   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2870   assert(!collector_state()->during_initial_mark_pause() ||
2871           collector_state()->gcs_are_young(), "sanity");
2872 
2873   // We also do not allow mixed GCs during marking.
2874   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2875 
2876   // Record whether this pause is an initial mark. When the current
2877   // thread has completed its logging output and it's safe to signal
2878   // the CM thread, the flag's value in the policy has been reset.
2879   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2880 
2881   // Inner scope for scope based logging, timers, and stats collection
2882   {
2883     EvacuationInfo evacuation_info;
2884 
2885     if (collector_state()->during_initial_mark_pause()) {
2886       // We are about to start a marking cycle, so we increment the
2887       // full collection counter.
2888       increment_old_marking_cycles_started();
2889       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2890     }
2891 
2892     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2893 
2894     GCTraceCPUTime tcpu;
2895 
2896     G1HeapVerifier::G1VerifyType verify_type;
2897     FormatBuffer<> gc_string("Pause ");
2898     if (collector_state()->during_initial_mark_pause()) {
2899       gc_string.append("Initial Mark");
2900       verify_type = G1HeapVerifier::G1VerifyInitialMark;
2901     } else if (collector_state()->gcs_are_young()) {
2902       gc_string.append("Young");
2903       verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2904     } else {
2905       gc_string.append("Mixed");
2906       verify_type = G1HeapVerifier::G1VerifyMixed;
2907     }
2908     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2909 
2910     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2911                                                                   workers()->active_workers(),
2912                                                                   Threads::number_of_non_daemon_threads());
2913     workers()->update_active_workers(active_workers);
2914     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2915 
2916     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2917     TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2918 
2919     // If the secondary_free_list is not empty, append it to the
2920     // free_list. No need to wait for the cleanup operation to finish;
2921     // the region allocation code will check the secondary_free_list
2922     // and wait if necessary. If the G1StressConcRegionFreeing flag is
2923     // set, skip this step so that the region allocation code has to
2924     // get entries from the secondary_free_list.
2925     if (!G1StressConcRegionFreeing) {
2926       append_secondary_free_list_if_not_empty_with_lock();
2927     }
2928 
2929     G1HeapTransition heap_transition(this);
2930     size_t heap_used_bytes_before_gc = used();
2931 
2932     // Don't dynamically change the number of GC threads this early.  A value of
2933     // 0 is used to indicate serial work.  When parallel work is done,
2934     // it will be set.
2935 
2936     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2937       IsGCActiveMark x;
2938 
2939       gc_prologue(false);
2940 
2941       if (VerifyRememberedSets) {
2942         log_info(gc, verify)("[Verifying RemSets before GC]");
2943         VerifyRegionRemSetClosure v_cl;
2944         heap_region_iterate(&v_cl);
2945       }
2946 
2947       _verifier->verify_before_gc(verify_type);
2948 
2949       _verifier->check_bitmaps("GC Start");
2950 
2951 #if COMPILER2_OR_JVMCI
2952       DerivedPointerTable::clear();
2953 #endif
2954 
2955       // Please see comment in g1CollectedHeap.hpp and
2956       // G1CollectedHeap::ref_processing_init() to see how
2957       // reference processing currently works in G1.
2958 
2959       // Enable discovery in the STW reference processor
2960       if (g1_policy()->should_process_references()) {
2961         ref_processor_stw()->enable_discovery();
2962       } else {
2963         ref_processor_stw()->disable_discovery();
2964       }
2965 
2966       {
2967         // We want to temporarily turn off discovery by the
2968         // CM ref processor, if necessary, and turn it back on
2969         // on again later if we do. Using a scoped
2970         // NoRefDiscovery object will do this.
2971         NoRefDiscovery no_cm_discovery(ref_processor_cm());
2972 
2973         // Forget the current alloc region (we might even choose it to be part
2974         // of the collection set!).
2975         _allocator->release_mutator_alloc_region();
2976 
2977         // This timing is only used by the ergonomics to handle our pause target.
2978         // It is unclear why this should not include the full pause. We will
2979         // investigate this in CR 7178365.
2980         //
2981         // Preserving the old comment here if that helps the investigation:
2982         //
2983         // The elapsed time induced by the start time below deliberately elides
2984         // the possible verification above.
2985         double sample_start_time_sec = os::elapsedTime();
2986 
2987         g1_policy()->record_collection_pause_start(sample_start_time_sec);
2988 
2989         if (collector_state()->during_initial_mark_pause()) {
2990           concurrent_mark()->checkpoint_roots_initial_pre();
2991         }
2992 
2993         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2994 
2995         evacuation_info.set_collectionset_regions(collection_set()->region_length());
2996 
2997         // Make sure the remembered sets are up to date. This needs to be
2998         // done before register_humongous_regions_with_cset(), because the
2999         // remembered sets are used there to choose eager reclaim candidates.
3000         // If the remembered sets are not up to date we might miss some
3001         // entries that need to be handled.
3002         g1_rem_set()->cleanupHRRS();
3003 
3004         register_humongous_regions_with_cset();
3005 
3006         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3007 
3008         // We call this after finalize_cset() to
3009         // ensure that the CSet has been finalized.
3010         _cm->verify_no_cset_oops();
3011 
3012         if (_hr_printer.is_active()) {
3013           G1PrintCollectionSetClosure cl(&_hr_printer);
3014           _collection_set.iterate(&cl);
3015         }
3016 
3017         // Initialize the GC alloc regions.
3018         _allocator->init_gc_alloc_regions(evacuation_info);
3019 
3020         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3021         pre_evacuate_collection_set();
3022 
3023         // Actually do the work...
3024         evacuate_collection_set(evacuation_info, &per_thread_states);
3025 
3026         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3027 
3028         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3029         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3030 
3031         eagerly_reclaim_humongous_regions();
3032 
3033         record_obj_copy_mem_stats();
3034         _survivor_evac_stats.adjust_desired_plab_sz();
3035         _old_evac_stats.adjust_desired_plab_sz();
3036 
3037         double start = os::elapsedTime();
3038         start_new_collection_set();
3039         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3040 
3041         if (evacuation_failed()) {
3042           set_used(recalculate_used());
3043           if (_archive_allocator != NULL) {
3044             _archive_allocator->clear_used();
3045           }
3046           for (uint i = 0; i < ParallelGCThreads; i++) {
3047             if (_evacuation_failed_info_array[i].has_failed()) {
3048               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3049             }
3050           }
3051         } else {
3052           // The "used" of the the collection set have already been subtracted
3053           // when they were freed.  Add in the bytes evacuated.
3054           increase_used(g1_policy()->bytes_copied_during_gc());
3055         }
3056 
3057         if (collector_state()->during_initial_mark_pause()) {
3058           // We have to do this before we notify the CM threads that
3059           // they can start working to make sure that all the
3060           // appropriate initialization is done on the CM object.
3061           concurrent_mark()->checkpoint_roots_initial_post();
3062           collector_state()->set_mark_in_progress(true);
3063           // Note that we don't actually trigger the CM thread at
3064           // this point. We do that later when we're sure that
3065           // the current thread has completed its logging output.
3066         }
3067 
3068         allocate_dummy_regions();
3069 
3070         _allocator->init_mutator_alloc_region();
3071 
3072         {
3073           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3074           if (expand_bytes > 0) {
3075             size_t bytes_before = capacity();
3076             // No need for an ergo logging here,
3077             // expansion_amount() does this when it returns a value > 0.
3078             double expand_ms;
3079             if (!expand(expand_bytes, _workers, &expand_ms)) {
3080               // We failed to expand the heap. Cannot do anything about it.
3081             }
3082             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3083           }
3084         }
3085 
3086         // We redo the verification but now wrt to the new CSet which
3087         // has just got initialized after the previous CSet was freed.
3088         _cm->verify_no_cset_oops();
3089 
3090         // This timing is only used by the ergonomics to handle our pause target.
3091         // It is unclear why this should not include the full pause. We will
3092         // investigate this in CR 7178365.
3093         double sample_end_time_sec = os::elapsedTime();
3094         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3095         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3096         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3097 
3098         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3099         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3100 
3101         if (VerifyRememberedSets) {
3102           log_info(gc, verify)("[Verifying RemSets after GC]");
3103           VerifyRegionRemSetClosure v_cl;
3104           heap_region_iterate(&v_cl);
3105         }
3106 
3107         _verifier->verify_after_gc(verify_type);
3108         _verifier->check_bitmaps("GC End");
3109 
3110         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3111         ref_processor_stw()->verify_no_references_recorded();
3112 
3113         // CM reference discovery will be re-enabled if necessary.
3114       }
3115 
3116 #ifdef TRACESPINNING
3117       ParallelTaskTerminator::print_termination_counts();
3118 #endif
3119 
3120       gc_epilogue(false);
3121     }
3122 
3123     // Print the remainder of the GC log output.
3124     if (evacuation_failed()) {
3125       log_info(gc)("To-space exhausted");
3126     }
3127 
3128     g1_policy()->print_phases();
3129     heap_transition.print();
3130 
3131     // It is not yet to safe to tell the concurrent mark to
3132     // start as we have some optional output below. We don't want the
3133     // output from the concurrent mark thread interfering with this
3134     // logging output either.
3135 
3136     _hrm.verify_optional();
3137     _verifier->verify_region_sets_optional();
3138 
3139     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3140     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3141 
3142     print_heap_after_gc();
3143     print_heap_regions();
3144     trace_heap_after_gc(_gc_tracer_stw);
3145 
3146     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3147     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3148     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3149     // before any GC notifications are raised.
3150     g1mm()->update_sizes();
3151 
3152     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3153     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3154     _gc_timer_stw->register_gc_end();
3155     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3156   }
3157   // It should now be safe to tell the concurrent mark thread to start
3158   // without its logging output interfering with the logging output
3159   // that came from the pause.
3160 
3161   if (should_start_conc_mark) {
3162     // CAUTION: after the doConcurrentMark() call below,
3163     // the concurrent marking thread(s) could be running
3164     // concurrently with us. Make sure that anything after
3165     // this point does not assume that we are the only GC thread
3166     // running. Note: of course, the actual marking work will
3167     // not start until the safepoint itself is released in
3168     // SuspendibleThreadSet::desynchronize().
3169     doConcurrentMark();
3170   }
3171 
3172   return true;
3173 }
3174 
3175 void G1CollectedHeap::remove_self_forwarding_pointers() {
3176   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3177   workers()->run_task(&rsfp_task);
3178 }
3179 
3180 void G1CollectedHeap::restore_after_evac_failure() {
3181   double remove_self_forwards_start = os::elapsedTime();
3182 
3183   remove_self_forwarding_pointers();
3184   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3185   _preserved_marks_set.restore(&task_executor);
3186 
3187   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3188 }
3189 
3190 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3191   if (!_evacuation_failed) {
3192     _evacuation_failed = true;
3193   }
3194 
3195   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3196   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3197 }
3198 
3199 bool G1ParEvacuateFollowersClosure::offer_termination() {
3200   G1ParScanThreadState* const pss = par_scan_state();
3201   start_term_time();
3202   const bool res = terminator()->offer_termination();
3203   end_term_time();
3204   return res;
3205 }
3206 
3207 void G1ParEvacuateFollowersClosure::do_void() {
3208   G1ParScanThreadState* const pss = par_scan_state();
3209   pss->trim_queue();
3210   do {
3211     pss->steal_and_trim_queue(queues());
3212   } while (!offer_termination());
3213 }
3214 
3215 class G1ParTask : public AbstractGangTask {
3216 protected:
3217   G1CollectedHeap*         _g1h;
3218   G1ParScanThreadStateSet* _pss;
3219   RefToScanQueueSet*       _queues;
3220   G1RootProcessor*         _root_processor;
3221   ParallelTaskTerminator   _terminator;
3222   uint                     _n_workers;
3223 
3224 public:
3225   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3226     : AbstractGangTask("G1 collection"),
3227       _g1h(g1h),
3228       _pss(per_thread_states),
3229       _queues(task_queues),
3230       _root_processor(root_processor),
3231       _terminator(n_workers, _queues),
3232       _n_workers(n_workers)
3233   {}
3234 
3235   void work(uint worker_id) {
3236     if (worker_id >= _n_workers) return;  // no work needed this round
3237 
3238     double start_sec = os::elapsedTime();
3239     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3240 
3241     {
3242       ResourceMark rm;
3243       HandleMark   hm;
3244 
3245       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3246 
3247       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3248       pss->set_ref_processor(rp);
3249 
3250       double start_strong_roots_sec = os::elapsedTime();
3251 
3252       _root_processor->evacuate_roots(pss->closures(), worker_id);
3253 
3254       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3255       // treating the nmethods visited to act as roots for concurrent marking.
3256       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3257       // objects copied by the current evacuation.
3258       _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3259                                                       pss->closures()->weak_codeblobs(),
3260                                                       worker_id);
3261 
3262       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3263 
3264       double term_sec = 0.0;
3265       size_t evac_term_attempts = 0;
3266       {
3267         double start = os::elapsedTime();
3268         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3269         evac.do_void();
3270 
3271         evac_term_attempts = evac.term_attempts();
3272         term_sec = evac.term_time();
3273         double elapsed_sec = os::elapsedTime() - start;
3274         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3275         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3276         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3277       }
3278 
3279       assert(pss->queue_is_empty(), "should be empty");
3280 
3281       if (log_is_enabled(Debug, gc, task, stats)) {
3282         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3283         size_t lab_waste;
3284         size_t lab_undo_waste;
3285         pss->waste(lab_waste, lab_undo_waste);
3286         _g1h->print_termination_stats(worker_id,
3287                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3288                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3289                                       term_sec * 1000.0,                          /* evac term time */
3290                                       evac_term_attempts,                         /* evac term attempts */
3291                                       lab_waste,                                  /* alloc buffer waste */
3292                                       lab_undo_waste                              /* undo waste */
3293                                       );
3294       }
3295 
3296       // Close the inner scope so that the ResourceMark and HandleMark
3297       // destructors are executed here and are included as part of the
3298       // "GC Worker Time".
3299     }
3300     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3301   }
3302 };
3303 
3304 void G1CollectedHeap::print_termination_stats_hdr() {
3305   log_debug(gc, task, stats)("GC Termination Stats");
3306   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3307   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3308   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3309 }
3310 
3311 void G1CollectedHeap::print_termination_stats(uint worker_id,
3312                                               double elapsed_ms,
3313                                               double strong_roots_ms,
3314                                               double term_ms,
3315                                               size_t term_attempts,
3316                                               size_t alloc_buffer_waste,
3317                                               size_t undo_waste) const {
3318   log_debug(gc, task, stats)
3319               ("%3d %9.2f %9.2f %6.2f "
3320                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3321                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3322                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3323                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3324                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3325                alloc_buffer_waste * HeapWordSize / K,
3326                undo_waste * HeapWordSize / K);
3327 }
3328 
3329 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3330 private:
3331   BoolObjectClosure* _is_alive;
3332   G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3333 
3334   int _initial_string_table_size;
3335   int _initial_symbol_table_size;
3336 
3337   bool  _process_strings;
3338   int _strings_processed;
3339   int _strings_removed;
3340 
3341   bool  _process_symbols;
3342   int _symbols_processed;
3343   int _symbols_removed;
3344 
3345   bool _process_string_dedup;
3346 
3347 public:
3348   G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3349     AbstractGangTask("String/Symbol Unlinking"),
3350     _is_alive(is_alive),
3351     _dedup_closure(is_alive, NULL, false),
3352     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3353     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3354     _process_string_dedup(process_string_dedup) {
3355 
3356     _initial_string_table_size = StringTable::the_table()->table_size();
3357     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3358     if (process_strings) {
3359       StringTable::clear_parallel_claimed_index();
3360     }
3361     if (process_symbols) {
3362       SymbolTable::clear_parallel_claimed_index();
3363     }
3364   }
3365 
3366   ~G1StringAndSymbolCleaningTask() {
3367     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3368               "claim value %d after unlink less than initial string table size %d",
3369               StringTable::parallel_claimed_index(), _initial_string_table_size);
3370     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3371               "claim value %d after unlink less than initial symbol table size %d",
3372               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3373 
3374     log_info(gc, stringtable)(
3375         "Cleaned string and symbol table, "
3376         "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3377         "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3378         strings_processed(), strings_removed(),
3379         symbols_processed(), symbols_removed());
3380   }
3381 
3382   void work(uint worker_id) {
3383     int strings_processed = 0;
3384     int strings_removed = 0;
3385     int symbols_processed = 0;
3386     int symbols_removed = 0;
3387     if (_process_strings) {
3388       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3389       Atomic::add(strings_processed, &_strings_processed);
3390       Atomic::add(strings_removed, &_strings_removed);
3391     }
3392     if (_process_symbols) {
3393       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3394       Atomic::add(symbols_processed, &_symbols_processed);
3395       Atomic::add(symbols_removed, &_symbols_removed);
3396     }
3397     if (_process_string_dedup) {
3398       G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3399     }
3400   }
3401 
3402   size_t strings_processed() const { return (size_t)_strings_processed; }
3403   size_t strings_removed()   const { return (size_t)_strings_removed; }
3404 
3405   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3406   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3407 };
3408 
3409 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3410 private:
3411   static Monitor* _lock;
3412 
3413   BoolObjectClosure* const _is_alive;
3414   const bool               _unloading_occurred;
3415   const uint               _num_workers;
3416 
3417   // Variables used to claim nmethods.
3418   CompiledMethod* _first_nmethod;
3419   CompiledMethod* volatile _claimed_nmethod;
3420 
3421   // The list of nmethods that need to be processed by the second pass.
3422   CompiledMethod* volatile _postponed_list;
3423   volatile uint            _num_entered_barrier;
3424 
3425  public:
3426   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3427       _is_alive(is_alive),
3428       _unloading_occurred(unloading_occurred),
3429       _num_workers(num_workers),
3430       _first_nmethod(NULL),
3431       _claimed_nmethod(NULL),
3432       _postponed_list(NULL),
3433       _num_entered_barrier(0)
3434   {
3435     CompiledMethod::increase_unloading_clock();
3436     // Get first alive nmethod
3437     CompiledMethodIterator iter = CompiledMethodIterator();
3438     if(iter.next_alive()) {
3439       _first_nmethod = iter.method();
3440     }
3441     _claimed_nmethod = _first_nmethod;
3442   }
3443 
3444   ~G1CodeCacheUnloadingTask() {
3445     CodeCache::verify_clean_inline_caches();
3446 
3447     CodeCache::set_needs_cache_clean(false);
3448     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3449 
3450     CodeCache::verify_icholder_relocations();
3451   }
3452 
3453  private:
3454   void add_to_postponed_list(CompiledMethod* nm) {
3455       CompiledMethod* old;
3456       do {
3457         old = _postponed_list;
3458         nm->set_unloading_next(old);
3459       } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3460   }
3461 
3462   void clean_nmethod(CompiledMethod* nm) {
3463     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3464 
3465     if (postponed) {
3466       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3467       add_to_postponed_list(nm);
3468     }
3469 
3470     // Mark that this thread has been cleaned/unloaded.
3471     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3472     nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3473   }
3474 
3475   void clean_nmethod_postponed(CompiledMethod* nm) {
3476     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3477   }
3478 
3479   static const int MaxClaimNmethods = 16;
3480 
3481   void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3482     CompiledMethod* first;
3483     CompiledMethodIterator last;
3484 
3485     do {
3486       *num_claimed_nmethods = 0;
3487 
3488       first = _claimed_nmethod;
3489       last = CompiledMethodIterator(first);
3490 
3491       if (first != NULL) {
3492 
3493         for (int i = 0; i < MaxClaimNmethods; i++) {
3494           if (!last.next_alive()) {
3495             break;
3496           }
3497           claimed_nmethods[i] = last.method();
3498           (*num_claimed_nmethods)++;
3499         }
3500       }
3501 
3502     } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3503   }
3504 
3505   CompiledMethod* claim_postponed_nmethod() {
3506     CompiledMethod* claim;
3507     CompiledMethod* next;
3508 
3509     do {
3510       claim = _postponed_list;
3511       if (claim == NULL) {
3512         return NULL;
3513       }
3514 
3515       next = claim->unloading_next();
3516 
3517     } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3518 
3519     return claim;
3520   }
3521 
3522  public:
3523   // Mark that we're done with the first pass of nmethod cleaning.
3524   void barrier_mark(uint worker_id) {
3525     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3526     _num_entered_barrier++;
3527     if (_num_entered_barrier == _num_workers) {
3528       ml.notify_all();
3529     }
3530   }
3531 
3532   // See if we have to wait for the other workers to
3533   // finish their first-pass nmethod cleaning work.
3534   void barrier_wait(uint worker_id) {
3535     if (_num_entered_barrier < _num_workers) {
3536       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3537       while (_num_entered_barrier < _num_workers) {
3538           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3539       }
3540     }
3541   }
3542 
3543   // Cleaning and unloading of nmethods. Some work has to be postponed
3544   // to the second pass, when we know which nmethods survive.
3545   void work_first_pass(uint worker_id) {
3546     // The first nmethods is claimed by the first worker.
3547     if (worker_id == 0 && _first_nmethod != NULL) {
3548       clean_nmethod(_first_nmethod);
3549       _first_nmethod = NULL;
3550     }
3551 
3552     int num_claimed_nmethods;
3553     CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3554 
3555     while (true) {
3556       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3557 
3558       if (num_claimed_nmethods == 0) {
3559         break;
3560       }
3561 
3562       for (int i = 0; i < num_claimed_nmethods; i++) {
3563         clean_nmethod(claimed_nmethods[i]);
3564       }
3565     }
3566   }
3567 
3568   void work_second_pass(uint worker_id) {
3569     CompiledMethod* nm;
3570     // Take care of postponed nmethods.
3571     while ((nm = claim_postponed_nmethod()) != NULL) {
3572       clean_nmethod_postponed(nm);
3573     }
3574   }
3575 };
3576 
3577 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3578 
3579 class G1KlassCleaningTask : public StackObj {
3580   BoolObjectClosure*                      _is_alive;
3581   volatile int                            _clean_klass_tree_claimed;
3582   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3583 
3584  public:
3585   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3586       _is_alive(is_alive),
3587       _clean_klass_tree_claimed(0),
3588       _klass_iterator() {
3589   }
3590 
3591  private:
3592   bool claim_clean_klass_tree_task() {
3593     if (_clean_klass_tree_claimed) {
3594       return false;
3595     }
3596 
3597     return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3598   }
3599 
3600   InstanceKlass* claim_next_klass() {
3601     Klass* klass;
3602     do {
3603       klass =_klass_iterator.next_klass();
3604     } while (klass != NULL && !klass->is_instance_klass());
3605 
3606     // this can be null so don't call InstanceKlass::cast
3607     return static_cast<InstanceKlass*>(klass);
3608   }
3609 
3610 public:
3611 
3612   void clean_klass(InstanceKlass* ik) {
3613     ik->clean_weak_instanceklass_links(_is_alive);
3614   }
3615 
3616   void work() {
3617     ResourceMark rm;
3618 
3619     // One worker will clean the subklass/sibling klass tree.
3620     if (claim_clean_klass_tree_task()) {
3621       Klass::clean_subklass_tree(_is_alive);
3622     }
3623 
3624     // All workers will help cleaning the classes,
3625     InstanceKlass* klass;
3626     while ((klass = claim_next_klass()) != NULL) {
3627       clean_klass(klass);
3628     }
3629   }
3630 };
3631 
3632 class G1ResolvedMethodCleaningTask : public StackObj {
3633   BoolObjectClosure* _is_alive;
3634   volatile int       _resolved_method_task_claimed;
3635 public:
3636   G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3637       _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3638 
3639   bool claim_resolved_method_task() {
3640     if (_resolved_method_task_claimed) {
3641       return false;
3642     }
3643     return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3644   }
3645 
3646   // These aren't big, one thread can do it all.
3647   void work() {
3648     if (claim_resolved_method_task()) {
3649       ResolvedMethodTable::unlink(_is_alive);
3650     }
3651   }
3652 };
3653 
3654 
3655 // To minimize the remark pause times, the tasks below are done in parallel.
3656 class G1ParallelCleaningTask : public AbstractGangTask {
3657 private:
3658   G1StringAndSymbolCleaningTask _string_symbol_task;
3659   G1CodeCacheUnloadingTask      _code_cache_task;
3660   G1KlassCleaningTask           _klass_cleaning_task;
3661   G1ResolvedMethodCleaningTask  _resolved_method_cleaning_task;
3662 
3663 public:
3664   // The constructor is run in the VMThread.
3665   G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3666       AbstractGangTask("Parallel Cleaning"),
3667       _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3668       _code_cache_task(num_workers, is_alive, unloading_occurred),
3669       _klass_cleaning_task(is_alive),
3670       _resolved_method_cleaning_task(is_alive) {
3671   }
3672 
3673   // The parallel work done by all worker threads.
3674   void work(uint worker_id) {
3675     // Do first pass of code cache cleaning.
3676     _code_cache_task.work_first_pass(worker_id);
3677 
3678     // Let the threads mark that the first pass is done.
3679     _code_cache_task.barrier_mark(worker_id);
3680 
3681     // Clean the Strings and Symbols.
3682     _string_symbol_task.work(worker_id);
3683 
3684     // Clean unreferenced things in the ResolvedMethodTable
3685     _resolved_method_cleaning_task.work();
3686 
3687     // Wait for all workers to finish the first code cache cleaning pass.
3688     _code_cache_task.barrier_wait(worker_id);
3689 
3690     // Do the second code cache cleaning work, which realize on
3691     // the liveness information gathered during the first pass.
3692     _code_cache_task.work_second_pass(worker_id);
3693 
3694     // Clean all klasses that were not unloaded.
3695     _klass_cleaning_task.work();
3696   }
3697 };
3698 
3699 
3700 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3701                                         bool class_unloading_occurred) {
3702   uint n_workers = workers()->active_workers();
3703 
3704   G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3705   workers()->run_task(&g1_unlink_task);
3706 }
3707 
3708 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3709                                        bool process_strings,
3710                                        bool process_symbols,
3711                                        bool process_string_dedup) {
3712   if (!process_strings && !process_symbols && !process_string_dedup) {
3713     // Nothing to clean.
3714     return;
3715   }
3716 
3717   G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3718   workers()->run_task(&g1_unlink_task);
3719 
3720 }
3721 
3722 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3723  private:
3724   DirtyCardQueueSet* _queue;
3725   G1CollectedHeap* _g1h;
3726  public:
3727   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3728     _queue(queue), _g1h(g1h) { }
3729 
3730   virtual void work(uint worker_id) {
3731     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3732     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3733 
3734     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3735     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3736 
3737     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3738   }
3739 };
3740 
3741 void G1CollectedHeap::redirty_logged_cards() {
3742   double redirty_logged_cards_start = os::elapsedTime();
3743 
3744   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3745   dirty_card_queue_set().reset_for_par_iteration();
3746   workers()->run_task(&redirty_task);
3747 
3748   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3749   dcq.merge_bufferlists(&dirty_card_queue_set());
3750   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3751 
3752   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3753 }
3754 
3755 // Weak Reference Processing support
3756 
3757 // An always "is_alive" closure that is used to preserve referents.
3758 // If the object is non-null then it's alive.  Used in the preservation
3759 // of referent objects that are pointed to by reference objects
3760 // discovered by the CM ref processor.
3761 class G1AlwaysAliveClosure: public BoolObjectClosure {
3762   G1CollectedHeap* _g1;
3763 public:
3764   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3765   bool do_object_b(oop p) {
3766     if (p != NULL) {
3767       return true;
3768     }
3769     return false;
3770   }
3771 };
3772 
3773 bool G1STWIsAliveClosure::do_object_b(oop p) {
3774   // An object is reachable if it is outside the collection set,
3775   // or is inside and copied.
3776   return !_g1->is_in_cset(p) || p->is_forwarded();
3777 }
3778 
3779 // Non Copying Keep Alive closure
3780 class G1KeepAliveClosure: public OopClosure {
3781   G1CollectedHeap* _g1;
3782 public:
3783   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3784   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3785   void do_oop(oop* p) {
3786     oop obj = *p;
3787     assert(obj != NULL, "the caller should have filtered out NULL values");
3788 
3789     const InCSetState cset_state = _g1->in_cset_state(obj);
3790     if (!cset_state.is_in_cset_or_humongous()) {
3791       return;
3792     }
3793     if (cset_state.is_in_cset()) {
3794       assert( obj->is_forwarded(), "invariant" );
3795       *p = obj->forwardee();
3796     } else {
3797       assert(!obj->is_forwarded(), "invariant" );
3798       assert(cset_state.is_humongous(),
3799              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3800       _g1->set_humongous_is_live(obj);
3801     }
3802   }
3803 };
3804 
3805 // Copying Keep Alive closure - can be called from both
3806 // serial and parallel code as long as different worker
3807 // threads utilize different G1ParScanThreadState instances
3808 // and different queues.
3809 
3810 class G1CopyingKeepAliveClosure: public OopClosure {
3811   G1CollectedHeap*         _g1h;
3812   OopClosure*              _copy_non_heap_obj_cl;
3813   G1ParScanThreadState*    _par_scan_state;
3814 
3815 public:
3816   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3817                             OopClosure* non_heap_obj_cl,
3818                             G1ParScanThreadState* pss):
3819     _g1h(g1h),
3820     _copy_non_heap_obj_cl(non_heap_obj_cl),
3821     _par_scan_state(pss)
3822   {}
3823 
3824   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3825   virtual void do_oop(      oop* p) { do_oop_work(p); }
3826 
3827   template <class T> void do_oop_work(T* p) {
3828     oop obj = oopDesc::load_decode_heap_oop(p);
3829 
3830     if (_g1h->is_in_cset_or_humongous(obj)) {
3831       // If the referent object has been forwarded (either copied
3832       // to a new location or to itself in the event of an
3833       // evacuation failure) then we need to update the reference
3834       // field and, if both reference and referent are in the G1
3835       // heap, update the RSet for the referent.
3836       //
3837       // If the referent has not been forwarded then we have to keep
3838       // it alive by policy. Therefore we have copy the referent.
3839       //
3840       // If the reference field is in the G1 heap then we can push
3841       // on the PSS queue. When the queue is drained (after each
3842       // phase of reference processing) the object and it's followers
3843       // will be copied, the reference field set to point to the
3844       // new location, and the RSet updated. Otherwise we need to
3845       // use the the non-heap or metadata closures directly to copy
3846       // the referent object and update the pointer, while avoiding
3847       // updating the RSet.
3848 
3849       if (_g1h->is_in_g1_reserved(p)) {
3850         _par_scan_state->push_on_queue(p);
3851       } else {
3852         assert(!Metaspace::contains((const void*)p),
3853                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3854         _copy_non_heap_obj_cl->do_oop(p);
3855       }
3856     }
3857   }
3858 };
3859 
3860 // Serial drain queue closure. Called as the 'complete_gc'
3861 // closure for each discovered list in some of the
3862 // reference processing phases.
3863 
3864 class G1STWDrainQueueClosure: public VoidClosure {
3865 protected:
3866   G1CollectedHeap* _g1h;
3867   G1ParScanThreadState* _par_scan_state;
3868 
3869   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3870 
3871 public:
3872   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3873     _g1h(g1h),
3874     _par_scan_state(pss)
3875   { }
3876 
3877   void do_void() {
3878     G1ParScanThreadState* const pss = par_scan_state();
3879     pss->trim_queue();
3880   }
3881 };
3882 
3883 // Parallel Reference Processing closures
3884 
3885 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3886 // processing during G1 evacuation pauses.
3887 
3888 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3889 private:
3890   G1CollectedHeap*          _g1h;
3891   G1ParScanThreadStateSet*  _pss;
3892   RefToScanQueueSet*        _queues;
3893   WorkGang*                 _workers;
3894   uint                      _active_workers;
3895 
3896 public:
3897   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3898                            G1ParScanThreadStateSet* per_thread_states,
3899                            WorkGang* workers,
3900                            RefToScanQueueSet *task_queues,
3901                            uint n_workers) :
3902     _g1h(g1h),
3903     _pss(per_thread_states),
3904     _queues(task_queues),
3905     _workers(workers),
3906     _active_workers(n_workers)
3907   {
3908     g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3909   }
3910 
3911   // Executes the given task using concurrent marking worker threads.
3912   virtual void execute(ProcessTask& task);
3913   virtual void execute(EnqueueTask& task);
3914 };
3915 
3916 // Gang task for possibly parallel reference processing
3917 
3918 class G1STWRefProcTaskProxy: public AbstractGangTask {
3919   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3920   ProcessTask&     _proc_task;
3921   G1CollectedHeap* _g1h;
3922   G1ParScanThreadStateSet* _pss;
3923   RefToScanQueueSet* _task_queues;
3924   ParallelTaskTerminator* _terminator;
3925 
3926 public:
3927   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3928                         G1CollectedHeap* g1h,
3929                         G1ParScanThreadStateSet* per_thread_states,
3930                         RefToScanQueueSet *task_queues,
3931                         ParallelTaskTerminator* terminator) :
3932     AbstractGangTask("Process reference objects in parallel"),
3933     _proc_task(proc_task),
3934     _g1h(g1h),
3935     _pss(per_thread_states),
3936     _task_queues(task_queues),
3937     _terminator(terminator)
3938   {}
3939 
3940   virtual void work(uint worker_id) {
3941     // The reference processing task executed by a single worker.
3942     ResourceMark rm;
3943     HandleMark   hm;
3944 
3945     G1STWIsAliveClosure is_alive(_g1h);
3946 
3947     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
3948     pss->set_ref_processor(NULL);
3949 
3950     // Keep alive closure.
3951     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3952 
3953     // Complete GC closure
3954     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3955 
3956     // Call the reference processing task's work routine.
3957     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3958 
3959     // Note we cannot assert that the refs array is empty here as not all
3960     // of the processing tasks (specifically phase2 - pp2_work) execute
3961     // the complete_gc closure (which ordinarily would drain the queue) so
3962     // the queue may not be empty.
3963   }
3964 };
3965 
3966 // Driver routine for parallel reference processing.
3967 // Creates an instance of the ref processing gang
3968 // task and has the worker threads execute it.
3969 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3970   assert(_workers != NULL, "Need parallel worker threads.");
3971 
3972   ParallelTaskTerminator terminator(_active_workers, _queues);
3973   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3974 
3975   _workers->run_task(&proc_task_proxy);
3976 }
3977 
3978 // Gang task for parallel reference enqueueing.
3979 
3980 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
3981   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
3982   EnqueueTask& _enq_task;
3983 
3984 public:
3985   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
3986     AbstractGangTask("Enqueue reference objects in parallel"),
3987     _enq_task(enq_task)
3988   { }
3989 
3990   virtual void work(uint worker_id) {
3991     _enq_task.work(worker_id);
3992   }
3993 };
3994 
3995 // Driver routine for parallel reference enqueueing.
3996 // Creates an instance of the ref enqueueing gang
3997 // task and has the worker threads execute it.
3998 
3999 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4000   assert(_workers != NULL, "Need parallel worker threads.");
4001 
4002   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4003 
4004   _workers->run_task(&enq_task_proxy);
4005 }
4006 
4007 // End of weak reference support closures
4008 
4009 // Abstract task used to preserve (i.e. copy) any referent objects
4010 // that are in the collection set and are pointed to by reference
4011 // objects discovered by the CM ref processor.
4012 
4013 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4014 protected:
4015   G1CollectedHeap*         _g1h;
4016   G1ParScanThreadStateSet* _pss;
4017   RefToScanQueueSet*       _queues;
4018   ParallelTaskTerminator   _terminator;
4019   uint                     _n_workers;
4020 
4021 public:
4022   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4023     AbstractGangTask("ParPreserveCMReferents"),
4024     _g1h(g1h),
4025     _pss(per_thread_states),
4026     _queues(task_queues),
4027     _terminator(workers, _queues),
4028     _n_workers(workers)
4029   {
4030     g1h->ref_processor_cm()->set_active_mt_degree(workers);
4031   }
4032 
4033   void work(uint worker_id) {
4034     G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4035 
4036     ResourceMark rm;
4037     HandleMark   hm;
4038 
4039     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4040     pss->set_ref_processor(NULL);
4041     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4042 
4043     // Is alive closure
4044     G1AlwaysAliveClosure always_alive(_g1h);
4045 
4046     // Copying keep alive closure. Applied to referent objects that need
4047     // to be copied.
4048     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4049 
4050     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4051 
4052     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4053     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4054 
4055     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4056     // So this must be true - but assert just in case someone decides to
4057     // change the worker ids.
4058     assert(worker_id < limit, "sanity");
4059     assert(!rp->discovery_is_atomic(), "check this code");
4060 
4061     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4062     for (uint idx = worker_id; idx < limit; idx += stride) {
4063       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4064 
4065       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4066       while (iter.has_next()) {
4067         // Since discovery is not atomic for the CM ref processor, we
4068         // can see some null referent objects.
4069         iter.load_ptrs(DEBUG_ONLY(true));
4070         oop ref = iter.obj();
4071 
4072         // This will filter nulls.
4073         if (iter.is_referent_alive()) {
4074           iter.make_referent_alive();
4075         }
4076         iter.move_to_next();
4077       }
4078     }
4079 
4080     // Drain the queue - which may cause stealing
4081     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4082     drain_queue.do_void();
4083     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4084     assert(pss->queue_is_empty(), "should be");
4085   }
4086 };
4087 
4088 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4089   // Any reference objects, in the collection set, that were 'discovered'
4090   // by the CM ref processor should have already been copied (either by
4091   // applying the external root copy closure to the discovered lists, or
4092   // by following an RSet entry).
4093   //
4094   // But some of the referents, that are in the collection set, that these
4095   // reference objects point to may not have been copied: the STW ref
4096   // processor would have seen that the reference object had already
4097   // been 'discovered' and would have skipped discovering the reference,
4098   // but would not have treated the reference object as a regular oop.
4099   // As a result the copy closure would not have been applied to the
4100   // referent object.
4101   //
4102   // We need to explicitly copy these referent objects - the references
4103   // will be processed at the end of remarking.
4104   //
4105   // We also need to do this copying before we process the reference
4106   // objects discovered by the STW ref processor in case one of these
4107   // referents points to another object which is also referenced by an
4108   // object discovered by the STW ref processor.
4109   double preserve_cm_referents_time = 0.0;
4110 
4111   // To avoid spawning task when there is no work to do, check that
4112   // a concurrent cycle is active and that some references have been
4113   // discovered.
4114   if (concurrent_mark()->cm_thread()->during_cycle() &&
4115       ref_processor_cm()->has_discovered_references()) {
4116     double preserve_cm_referents_start = os::elapsedTime();
4117     uint no_of_gc_workers = workers()->active_workers();
4118     G1ParPreserveCMReferentsTask keep_cm_referents(this,
4119                                                    per_thread_states,
4120                                                    no_of_gc_workers,
4121                                                    _task_queues);
4122     workers()->run_task(&keep_cm_referents);
4123     preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4124   }
4125 
4126   g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4127 }
4128 
4129 // Weak Reference processing during an evacuation pause (part 1).
4130 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4131   double ref_proc_start = os::elapsedTime();
4132 
4133   ReferenceProcessor* rp = _ref_processor_stw;
4134   assert(rp->discovery_enabled(), "should have been enabled");
4135 
4136   // Closure to test whether a referent is alive.
4137   G1STWIsAliveClosure is_alive(this);
4138 
4139   // Even when parallel reference processing is enabled, the processing
4140   // of JNI refs is serial and performed serially by the current thread
4141   // rather than by a worker. The following PSS will be used for processing
4142   // JNI refs.
4143 
4144   // Use only a single queue for this PSS.
4145   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4146   pss->set_ref_processor(NULL);
4147   assert(pss->queue_is_empty(), "pre-condition");
4148 
4149   // Keep alive closure.
4150   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4151 
4152   // Serial Complete GC closure
4153   G1STWDrainQueueClosure drain_queue(this, pss);
4154 
4155   // Setup the soft refs policy...
4156   rp->setup_policy(false);
4157 
4158   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4159 
4160   ReferenceProcessorStats stats;
4161   if (!rp->processing_is_mt()) {
4162     // Serial reference processing...
4163     stats = rp->process_discovered_references(&is_alive,
4164                                               &keep_alive,
4165                                               &drain_queue,
4166                                               NULL,
4167                                               pt);
4168   } else {
4169     uint no_of_gc_workers = workers()->active_workers();
4170 
4171     // Parallel reference processing
4172     assert(no_of_gc_workers <= rp->max_num_q(),
4173            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4174            no_of_gc_workers,  rp->max_num_q());
4175 
4176     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4177     stats = rp->process_discovered_references(&is_alive,
4178                                               &keep_alive,
4179                                               &drain_queue,
4180                                               &par_task_executor,
4181                                               pt);
4182   }
4183 
4184   _gc_tracer_stw->report_gc_reference_stats(stats);
4185 
4186   // We have completed copying any necessary live referent objects.
4187   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4188 
4189   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4190   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4191 }
4192 
4193 // Weak Reference processing during an evacuation pause (part 2).
4194 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4195   double ref_enq_start = os::elapsedTime();
4196 
4197   ReferenceProcessor* rp = _ref_processor_stw;
4198   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4199 
4200   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4201 
4202   // Now enqueue any remaining on the discovered lists on to
4203   // the pending list.
4204   if (!rp->processing_is_mt()) {
4205     // Serial reference processing...
4206     rp->enqueue_discovered_references(NULL, pt);
4207   } else {
4208     // Parallel reference enqueueing
4209 
4210     uint n_workers = workers()->active_workers();
4211 
4212     assert(n_workers <= rp->max_num_q(),
4213            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4214            n_workers,  rp->max_num_q());
4215 
4216     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4217     rp->enqueue_discovered_references(&par_task_executor, pt);
4218   }
4219 
4220   rp->verify_no_references_recorded();
4221   assert(!rp->discovery_enabled(), "should have been disabled");
4222 
4223   // If during an initial mark pause we install a pending list head which is not otherwise reachable
4224   // ensure that it is marked in the bitmap for concurrent marking to discover.
4225   if (collector_state()->during_initial_mark_pause()) {
4226     oop pll_head = Universe::reference_pending_list();
4227     if (pll_head != NULL) {
4228       _cm->mark_in_next_bitmap(pll_head);
4229     }
4230   }
4231 
4232   // FIXME
4233   // CM's reference processing also cleans up the string and symbol tables.
4234   // Should we do that here also? We could, but it is a serial operation
4235   // and could significantly increase the pause time.
4236 
4237   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4238   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4239 }
4240 
4241 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4242   double merge_pss_time_start = os::elapsedTime();
4243   per_thread_states->flush();
4244   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4245 }
4246 
4247 void G1CollectedHeap::pre_evacuate_collection_set() {
4248   _expand_heap_after_alloc_failure = true;
4249   _evacuation_failed = false;
4250 
4251   // Disable the hot card cache.
4252   _hot_card_cache->reset_hot_cache_claimed_index();
4253   _hot_card_cache->set_use_cache(false);
4254 
4255   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4256   _preserved_marks_set.assert_empty();
4257 
4258   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4259 
4260   // InitialMark needs claim bits to keep track of the marked-through CLDs.
4261   if (collector_state()->during_initial_mark_pause()) {
4262     double start_clear_claimed_marks = os::elapsedTime();
4263 
4264     ClassLoaderDataGraph::clear_claimed_marks();
4265 
4266     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4267     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4268   }
4269 }
4270 
4271 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4272   // Should G1EvacuationFailureALot be in effect for this GC?
4273   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4274 
4275   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4276 
4277   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4278 
4279   double start_par_time_sec = os::elapsedTime();
4280   double end_par_time_sec;
4281 
4282   {
4283     const uint n_workers = workers()->active_workers();
4284     G1RootProcessor root_processor(this, n_workers);
4285     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4286 
4287     print_termination_stats_hdr();
4288 
4289     workers()->run_task(&g1_par_task);
4290     end_par_time_sec = os::elapsedTime();
4291 
4292     // Closing the inner scope will execute the destructor
4293     // for the G1RootProcessor object. We record the current
4294     // elapsed time before closing the scope so that time
4295     // taken for the destructor is NOT included in the
4296     // reported parallel time.
4297   }
4298 
4299   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4300   phase_times->record_par_time(par_time_ms);
4301 
4302   double code_root_fixup_time_ms =
4303         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4304   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4305 }
4306 
4307 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4308   // Process any discovered reference objects - we have
4309   // to do this _before_ we retire the GC alloc regions
4310   // as we may have to copy some 'reachable' referent
4311   // objects (and their reachable sub-graphs) that were
4312   // not copied during the pause.
4313   if (g1_policy()->should_process_references()) {
4314     preserve_cm_referents(per_thread_states);
4315     process_discovered_references(per_thread_states);
4316   } else {
4317     ref_processor_stw()->verify_no_references_recorded();
4318   }
4319 
4320   G1STWIsAliveClosure is_alive(this);
4321   G1KeepAliveClosure keep_alive(this);
4322 
4323   {
4324     double start = os::elapsedTime();
4325 
4326     WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4327 
4328     double time_ms = (os::elapsedTime() - start) * 1000.0;
4329     g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4330   }
4331 
4332   if (G1StringDedup::is_enabled()) {
4333     double fixup_start = os::elapsedTime();
4334 
4335     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4336 
4337     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4338     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4339   }
4340 
4341   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4342 
4343   if (evacuation_failed()) {
4344     restore_after_evac_failure();
4345 
4346     // Reset the G1EvacuationFailureALot counters and flags
4347     // Note: the values are reset only when an actual
4348     // evacuation failure occurs.
4349     NOT_PRODUCT(reset_evacuation_should_fail();)
4350   }
4351 
4352   _preserved_marks_set.assert_empty();
4353 
4354   // Enqueue any remaining references remaining on the STW
4355   // reference processor's discovered lists. We need to do
4356   // this after the card table is cleaned (and verified) as
4357   // the act of enqueueing entries on to the pending list
4358   // will log these updates (and dirty their associated
4359   // cards). We need these updates logged to update any
4360   // RSets.
4361   if (g1_policy()->should_process_references()) {
4362     enqueue_discovered_references(per_thread_states);
4363   } else {
4364     g1_policy()->phase_times()->record_ref_enq_time(0);
4365   }
4366 
4367   _allocator->release_gc_alloc_regions(evacuation_info);
4368 
4369   merge_per_thread_state_info(per_thread_states);
4370 
4371   // Reset and re-enable the hot card cache.
4372   // Note the counts for the cards in the regions in the
4373   // collection set are reset when the collection set is freed.
4374   _hot_card_cache->reset_hot_cache();
4375   _hot_card_cache->set_use_cache(true);
4376 
4377   purge_code_root_memory();
4378 
4379   redirty_logged_cards();
4380 #if COMPILER2_OR_JVMCI
4381   double start = os::elapsedTime();
4382   DerivedPointerTable::update_pointers();
4383   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4384 #endif
4385   g1_policy()->print_age_table();
4386 }
4387 
4388 void G1CollectedHeap::record_obj_copy_mem_stats() {
4389   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4390 
4391   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4392                                                create_g1_evac_summary(&_old_evac_stats));
4393 }
4394 
4395 void G1CollectedHeap::free_region(HeapRegion* hr,
4396                                   FreeRegionList* free_list,
4397                                   bool skip_remset,
4398                                   bool skip_hot_card_cache,
4399                                   bool locked) {
4400   assert(!hr->is_free(), "the region should not be free");
4401   assert(!hr->is_empty(), "the region should not be empty");
4402   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4403   assert(free_list != NULL, "pre-condition");
4404 
4405   if (G1VerifyBitmaps) {
4406     MemRegion mr(hr->bottom(), hr->end());
4407     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4408   }
4409 
4410   // Clear the card counts for this region.
4411   // Note: we only need to do this if the region is not young
4412   // (since we don't refine cards in young regions).
4413   if (!skip_hot_card_cache && !hr->is_young()) {
4414     _hot_card_cache->reset_card_counts(hr);
4415   }
4416   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4417   free_list->add_ordered(hr);
4418 }
4419 
4420 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4421                                             FreeRegionList* free_list,
4422                                             bool skip_remset) {
4423   assert(hr->is_humongous(), "this is only for humongous regions");
4424   assert(free_list != NULL, "pre-condition");
4425   hr->clear_humongous();
4426   free_region(hr, free_list, skip_remset);
4427 }
4428 
4429 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4430                                            const uint humongous_regions_removed) {
4431   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4432     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4433     _old_set.bulk_remove(old_regions_removed);
4434     _humongous_set.bulk_remove(humongous_regions_removed);
4435   }
4436 
4437 }
4438 
4439 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4440   assert(list != NULL, "list can't be null");
4441   if (!list->is_empty()) {
4442     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4443     _hrm.insert_list_into_free_list(list);
4444   }
4445 }
4446 
4447 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4448   decrease_used(bytes);
4449 }
4450 
4451 class G1ParScrubRemSetTask: public AbstractGangTask {
4452 protected:
4453   G1RemSet* _g1rs;
4454   HeapRegionClaimer _hrclaimer;
4455 
4456 public:
4457   G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4458     AbstractGangTask("G1 ScrubRS"),
4459     _g1rs(g1_rs),
4460     _hrclaimer(num_workers) {
4461   }
4462 
4463   void work(uint worker_id) {
4464     _g1rs->scrub(worker_id, &_hrclaimer);
4465   }
4466 };
4467 
4468 void G1CollectedHeap::scrub_rem_set() {
4469   uint num_workers = workers()->active_workers();
4470   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4471   workers()->run_task(&g1_par_scrub_rs_task);
4472 }
4473 
4474 class G1FreeCollectionSetTask : public AbstractGangTask {
4475 private:
4476 
4477   // Closure applied to all regions in the collection set to do work that needs to
4478   // be done serially in a single thread.
4479   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4480   private:
4481     EvacuationInfo* _evacuation_info;
4482     const size_t* _surviving_young_words;
4483 
4484     // Bytes used in successfully evacuated regions before the evacuation.
4485     size_t _before_used_bytes;
4486     // Bytes used in unsucessfully evacuated regions before the evacuation
4487     size_t _after_used_bytes;
4488 
4489     size_t _bytes_allocated_in_old_since_last_gc;
4490 
4491     size_t _failure_used_words;
4492     size_t _failure_waste_words;
4493 
4494     FreeRegionList _local_free_list;
4495   public:
4496     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4497       HeapRegionClosure(),
4498       _evacuation_info(evacuation_info),
4499       _surviving_young_words(surviving_young_words),
4500       _before_used_bytes(0),
4501       _after_used_bytes(0),
4502       _bytes_allocated_in_old_since_last_gc(0),
4503       _failure_used_words(0),
4504       _failure_waste_words(0),
4505       _local_free_list("Local Region List for CSet Freeing") {
4506     }
4507 
4508     virtual bool doHeapRegion(HeapRegion* r) {
4509       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4510 
4511       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4512       g1h->clear_in_cset(r);
4513 
4514       if (r->is_young()) {
4515         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4516                "Young index %d is wrong for region %u of type %s with %u young regions",
4517                r->young_index_in_cset(),
4518                r->hrm_index(),
4519                r->get_type_str(),
4520                g1h->collection_set()->young_region_length());
4521         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4522         r->record_surv_words_in_group(words_survived);
4523       }
4524 
4525       if (!r->evacuation_failed()) {
4526         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4527         _before_used_bytes += r->used();
4528         g1h->free_region(r,
4529                          &_local_free_list,
4530                          true, /* skip_remset */
4531                          true, /* skip_hot_card_cache */
4532                          true  /* locked */);
4533       } else {
4534         r->uninstall_surv_rate_group();
4535         r->set_young_index_in_cset(-1);
4536         r->set_evacuation_failed(false);
4537         // When moving a young gen region to old gen, we "allocate" that whole region
4538         // there. This is in addition to any already evacuated objects. Notify the
4539         // policy about that.
4540         // Old gen regions do not cause an additional allocation: both the objects
4541         // still in the region and the ones already moved are accounted for elsewhere.
4542         if (r->is_young()) {
4543           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4544         }
4545         // The region is now considered to be old.
4546         r->set_old();
4547         // Do some allocation statistics accounting. Regions that failed evacuation
4548         // are always made old, so there is no need to update anything in the young
4549         // gen statistics, but we need to update old gen statistics.
4550         size_t used_words = r->marked_bytes() / HeapWordSize;
4551 
4552         _failure_used_words += used_words;
4553         _failure_waste_words += HeapRegion::GrainWords - used_words;
4554 
4555         g1h->old_set_add(r);
4556         _after_used_bytes += r->used();
4557       }
4558       return false;
4559     }
4560 
4561     void complete_work() {
4562       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4563 
4564       _evacuation_info->set_regions_freed(_local_free_list.length());
4565       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4566 
4567       g1h->prepend_to_freelist(&_local_free_list);
4568       g1h->decrement_summary_bytes(_before_used_bytes);
4569 
4570       G1Policy* policy = g1h->g1_policy();
4571       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4572 
4573       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4574     }
4575   };
4576 
4577   G1CollectionSet* _collection_set;
4578   G1SerialFreeCollectionSetClosure _cl;
4579   const size_t* _surviving_young_words;
4580 
4581   size_t _rs_lengths;
4582 
4583   volatile jint _serial_work_claim;
4584 
4585   struct WorkItem {
4586     uint region_idx;
4587     bool is_young;
4588     bool evacuation_failed;
4589 
4590     WorkItem(HeapRegion* r) {
4591       region_idx = r->hrm_index();
4592       is_young = r->is_young();
4593       evacuation_failed = r->evacuation_failed();
4594     }
4595   };
4596 
4597   volatile size_t _parallel_work_claim;
4598   size_t _num_work_items;
4599   WorkItem* _work_items;
4600 
4601   void do_serial_work() {
4602     // Need to grab the lock to be allowed to modify the old region list.
4603     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4604     _collection_set->iterate(&_cl);
4605   }
4606 
4607   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4608     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4609 
4610     HeapRegion* r = g1h->region_at(region_idx);
4611     assert(!g1h->is_on_master_free_list(r), "sanity");
4612 
4613     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4614 
4615     if (!is_young) {
4616       g1h->_hot_card_cache->reset_card_counts(r);
4617     }
4618 
4619     if (!evacuation_failed) {
4620       r->rem_set()->clear_locked();
4621     }
4622   }
4623 
4624   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4625   private:
4626     size_t _cur_idx;
4627     WorkItem* _work_items;
4628   public:
4629     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4630 
4631     virtual bool doHeapRegion(HeapRegion* r) {
4632       _work_items[_cur_idx++] = WorkItem(r);
4633       return false;
4634     }
4635   };
4636 
4637   void prepare_work() {
4638     G1PrepareFreeCollectionSetClosure cl(_work_items);
4639     _collection_set->iterate(&cl);
4640   }
4641 
4642   void complete_work() {
4643     _cl.complete_work();
4644 
4645     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4646     policy->record_max_rs_lengths(_rs_lengths);
4647     policy->cset_regions_freed();
4648   }
4649 public:
4650   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4651     AbstractGangTask("G1 Free Collection Set"),
4652     _cl(evacuation_info, surviving_young_words),
4653     _collection_set(collection_set),
4654     _surviving_young_words(surviving_young_words),
4655     _serial_work_claim(0),
4656     _rs_lengths(0),
4657     _parallel_work_claim(0),
4658     _num_work_items(collection_set->region_length()),
4659     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4660     prepare_work();
4661   }
4662 
4663   ~G1FreeCollectionSetTask() {
4664     complete_work();
4665     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4666   }
4667 
4668   // Chunk size for work distribution. The chosen value has been determined experimentally
4669   // to be a good tradeoff between overhead and achievable parallelism.
4670   static uint chunk_size() { return 32; }
4671 
4672   virtual void work(uint worker_id) {
4673     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4674 
4675     // Claim serial work.
4676     if (_serial_work_claim == 0) {
4677       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4678       if (value == 0) {
4679         double serial_time = os::elapsedTime();
4680         do_serial_work();
4681         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4682       }
4683     }
4684 
4685     // Start parallel work.
4686     double young_time = 0.0;
4687     bool has_young_time = false;
4688     double non_young_time = 0.0;
4689     bool has_non_young_time = false;
4690 
4691     while (true) {
4692       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4693       size_t cur = end - chunk_size();
4694 
4695       if (cur >= _num_work_items) {
4696         break;
4697       }
4698 
4699       double start_time = os::elapsedTime();
4700 
4701       end = MIN2(end, _num_work_items);
4702 
4703       for (; cur < end; cur++) {
4704         bool is_young = _work_items[cur].is_young;
4705 
4706         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4707 
4708         double end_time = os::elapsedTime();
4709         double time_taken = end_time - start_time;
4710         if (is_young) {
4711           young_time += time_taken;
4712           has_young_time = true;
4713         } else {
4714           non_young_time += time_taken;
4715           has_non_young_time = true;
4716         }
4717         start_time = end_time;
4718       }
4719     }
4720 
4721     if (has_young_time) {
4722       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4723     }
4724     if (has_non_young_time) {
4725       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4726     }
4727   }
4728 };
4729 
4730 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4731   _eden.clear();
4732 
4733   double free_cset_start_time = os::elapsedTime();
4734 
4735   {
4736     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4737     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4738 
4739     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4740 
4741     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4742                         cl.name(),
4743                         num_workers,
4744                         _collection_set.region_length());
4745     workers()->run_task(&cl, num_workers);
4746   }
4747   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4748 
4749   collection_set->clear();
4750 }
4751 
4752 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4753  private:
4754   FreeRegionList* _free_region_list;
4755   HeapRegionSet* _proxy_set;
4756   uint _humongous_objects_reclaimed;
4757   uint _humongous_regions_reclaimed;
4758   size_t _freed_bytes;
4759  public:
4760 
4761   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4762     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4763   }
4764 
4765   virtual bool doHeapRegion(HeapRegion* r) {
4766     if (!r->is_starts_humongous()) {
4767       return false;
4768     }
4769 
4770     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4771 
4772     oop obj = (oop)r->bottom();
4773     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4774 
4775     // The following checks whether the humongous object is live are sufficient.
4776     // The main additional check (in addition to having a reference from the roots
4777     // or the young gen) is whether the humongous object has a remembered set entry.
4778     //
4779     // A humongous object cannot be live if there is no remembered set for it
4780     // because:
4781     // - there can be no references from within humongous starts regions referencing
4782     // the object because we never allocate other objects into them.
4783     // (I.e. there are no intra-region references that may be missed by the
4784     // remembered set)
4785     // - as soon there is a remembered set entry to the humongous starts region
4786     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4787     // until the end of a concurrent mark.
4788     //
4789     // It is not required to check whether the object has been found dead by marking
4790     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4791     // all objects allocated during that time are considered live.
4792     // SATB marking is even more conservative than the remembered set.
4793     // So if at this point in the collection there is no remembered set entry,
4794     // nobody has a reference to it.
4795     // At the start of collection we flush all refinement logs, and remembered sets
4796     // are completely up-to-date wrt to references to the humongous object.
4797     //
4798     // Other implementation considerations:
4799     // - never consider object arrays at this time because they would pose
4800     // considerable effort for cleaning up the the remembered sets. This is
4801     // required because stale remembered sets might reference locations that
4802     // are currently allocated into.
4803     uint region_idx = r->hrm_index();
4804     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4805         !r->rem_set()->is_empty()) {
4806       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",
4807                                region_idx,
4808                                (size_t)obj->size() * HeapWordSize,
4809                                p2i(r->bottom()),
4810                                r->rem_set()->occupied(),
4811                                r->rem_set()->strong_code_roots_list_length(),
4812                                next_bitmap->is_marked(r->bottom()),
4813                                g1h->is_humongous_reclaim_candidate(region_idx),
4814                                obj->is_typeArray()
4815                               );
4816       return false;
4817     }
4818 
4819     guarantee(obj->is_typeArray(),
4820               "Only eagerly reclaiming type arrays is supported, but the object "
4821               PTR_FORMAT " is not.", p2i(r->bottom()));
4822 
4823     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",
4824                              region_idx,
4825                              (size_t)obj->size() * HeapWordSize,
4826                              p2i(r->bottom()),
4827                              r->rem_set()->occupied(),
4828                              r->rem_set()->strong_code_roots_list_length(),
4829                              next_bitmap->is_marked(r->bottom()),
4830                              g1h->is_humongous_reclaim_candidate(region_idx),
4831                              obj->is_typeArray()
4832                             );
4833 
4834     // Need to clear mark bit of the humongous object if already set.
4835     if (next_bitmap->is_marked(r->bottom())) {
4836       next_bitmap->clear(r->bottom());
4837     }
4838     _humongous_objects_reclaimed++;
4839     do {
4840       HeapRegion* next = g1h->next_region_in_humongous(r);
4841       _freed_bytes += r->used();
4842       r->set_containing_set(NULL);
4843       _humongous_regions_reclaimed++;
4844       g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4845       r = next;
4846     } while (r != NULL);
4847 
4848     return false;
4849   }
4850 
4851   uint humongous_objects_reclaimed() {
4852     return _humongous_objects_reclaimed;
4853   }
4854 
4855   uint humongous_regions_reclaimed() {
4856     return _humongous_regions_reclaimed;
4857   }
4858 
4859   size_t bytes_freed() const {
4860     return _freed_bytes;
4861   }
4862 };
4863 
4864 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4865   assert_at_safepoint(true);
4866 
4867   if (!G1EagerReclaimHumongousObjects ||
4868       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4869     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4870     return;
4871   }
4872 
4873   double start_time = os::elapsedTime();
4874 
4875   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4876 
4877   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4878   heap_region_iterate(&cl);
4879 
4880   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4881 
4882   G1HRPrinter* hrp = hr_printer();
4883   if (hrp->is_active()) {
4884     FreeRegionListIterator iter(&local_cleanup_list);
4885     while (iter.more_available()) {
4886       HeapRegion* hr = iter.get_next();
4887       hrp->cleanup(hr);
4888     }
4889   }
4890 
4891   prepend_to_freelist(&local_cleanup_list);
4892   decrement_summary_bytes(cl.bytes_freed());
4893 
4894   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4895                                                                     cl.humongous_objects_reclaimed());
4896 }
4897 
4898 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4899 public:
4900   virtual bool doHeapRegion(HeapRegion* r) {
4901     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4902     G1CollectedHeap::heap()->clear_in_cset(r);
4903     r->set_young_index_in_cset(-1);
4904     return false;
4905   }
4906 };
4907 
4908 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4909   G1AbandonCollectionSetClosure cl;
4910   collection_set->iterate(&cl);
4911 
4912   collection_set->clear();
4913   collection_set->stop_incremental_building();
4914 }
4915 
4916 void G1CollectedHeap::set_free_regions_coming() {
4917   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4918 
4919   assert(!free_regions_coming(), "pre-condition");
4920   _free_regions_coming = true;
4921 }
4922 
4923 void G1CollectedHeap::reset_free_regions_coming() {
4924   assert(free_regions_coming(), "pre-condition");
4925 
4926   {
4927     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4928     _free_regions_coming = false;
4929     SecondaryFreeList_lock->notify_all();
4930   }
4931 
4932   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4933 }
4934 
4935 void G1CollectedHeap::wait_while_free_regions_coming() {
4936   // Most of the time we won't have to wait, so let's do a quick test
4937   // first before we take the lock.
4938   if (!free_regions_coming()) {
4939     return;
4940   }
4941 
4942   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4943 
4944   {
4945     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4946     while (free_regions_coming()) {
4947       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4948     }
4949   }
4950 
4951   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
4952 }
4953 
4954 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4955   return _allocator->is_retained_old_region(hr);
4956 }
4957 
4958 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4959   _eden.add(hr);
4960   _g1_policy->set_region_eden(hr);
4961 }
4962 
4963 #ifdef ASSERT
4964 
4965 class NoYoungRegionsClosure: public HeapRegionClosure {
4966 private:
4967   bool _success;
4968 public:
4969   NoYoungRegionsClosure() : _success(true) { }
4970   bool doHeapRegion(HeapRegion* r) {
4971     if (r->is_young()) {
4972       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4973                             p2i(r->bottom()), p2i(r->end()));
4974       _success = false;
4975     }
4976     return false;
4977   }
4978   bool success() { return _success; }
4979 };
4980 
4981 bool G1CollectedHeap::check_young_list_empty() {
4982   bool ret = (young_regions_count() == 0);
4983 
4984   NoYoungRegionsClosure closure;
4985   heap_region_iterate(&closure);
4986   ret = ret && closure.success();
4987 
4988   return ret;
4989 }
4990 
4991 #endif // ASSERT
4992 
4993 class TearDownRegionSetsClosure : public HeapRegionClosure {
4994 private:
4995   HeapRegionSet *_old_set;
4996 
4997 public:
4998   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4999 
5000   bool doHeapRegion(HeapRegion* r) {
5001     if (r->is_old()) {
5002       _old_set->remove(r);
5003     } else if(r->is_young()) {
5004       r->uninstall_surv_rate_group();
5005     } else {
5006       // We ignore free regions, we'll empty the free list afterwards.
5007       // We ignore humongous regions, we're not tearing down the
5008       // humongous regions set.
5009       assert(r->is_free() || r->is_humongous(),
5010              "it cannot be another type");
5011     }
5012     return false;
5013   }
5014 
5015   ~TearDownRegionSetsClosure() {
5016     assert(_old_set->is_empty(), "post-condition");
5017   }
5018 };
5019 
5020 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5021   assert_at_safepoint(true /* should_be_vm_thread */);
5022 
5023   if (!free_list_only) {
5024     TearDownRegionSetsClosure cl(&_old_set);
5025     heap_region_iterate(&cl);
5026 
5027     // Note that emptying the _young_list is postponed and instead done as
5028     // the first step when rebuilding the regions sets again. The reason for
5029     // this is that during a full GC string deduplication needs to know if
5030     // a collected region was young or old when the full GC was initiated.
5031   }
5032   _hrm.remove_all_free_regions();
5033 }
5034 
5035 void G1CollectedHeap::increase_used(size_t bytes) {
5036   _summary_bytes_used += bytes;
5037 }
5038 
5039 void G1CollectedHeap::decrease_used(size_t bytes) {
5040   assert(_summary_bytes_used >= bytes,
5041          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5042          _summary_bytes_used, bytes);
5043   _summary_bytes_used -= bytes;
5044 }
5045 
5046 void G1CollectedHeap::set_used(size_t bytes) {
5047   _summary_bytes_used = bytes;
5048 }
5049 
5050 class RebuildRegionSetsClosure : public HeapRegionClosure {
5051 private:
5052   bool            _free_list_only;
5053   HeapRegionSet*   _old_set;
5054   HeapRegionManager*   _hrm;
5055   size_t          _total_used;
5056 
5057 public:
5058   RebuildRegionSetsClosure(bool free_list_only,
5059                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5060     _free_list_only(free_list_only),
5061     _old_set(old_set), _hrm(hrm), _total_used(0) {
5062     assert(_hrm->num_free_regions() == 0, "pre-condition");
5063     if (!free_list_only) {
5064       assert(_old_set->is_empty(), "pre-condition");
5065     }
5066   }
5067 
5068   bool doHeapRegion(HeapRegion* r) {
5069     if (r->is_empty()) {
5070       // Add free regions to the free list
5071       r->set_free();
5072       r->set_allocation_context(AllocationContext::system());
5073       _hrm->insert_into_free_list(r);
5074     } else if (!_free_list_only) {
5075 
5076       if (r->is_humongous()) {
5077         // We ignore humongous regions. We left the humongous set unchanged.
5078       } else {
5079         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5080         // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5081         r->move_to_old();
5082         _old_set->add(r);
5083       }
5084       _total_used += r->used();
5085     }
5086 
5087     return false;
5088   }
5089 
5090   size_t total_used() {
5091     return _total_used;
5092   }
5093 };
5094 
5095 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5096   assert_at_safepoint(true /* should_be_vm_thread */);
5097 
5098   if (!free_list_only) {
5099     _eden.clear();
5100     _survivor.clear();
5101   }
5102 
5103   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5104   heap_region_iterate(&cl);
5105 
5106   if (!free_list_only) {
5107     set_used(cl.total_used());
5108     if (_archive_allocator != NULL) {
5109       _archive_allocator->clear_used();
5110     }
5111   }
5112   assert(used_unlocked() == recalculate_used(),
5113          "inconsistent used_unlocked(), "
5114          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5115          used_unlocked(), recalculate_used());
5116 }
5117 
5118 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5119   HeapRegion* hr = heap_region_containing(p);
5120   return hr->is_in(p);
5121 }
5122 
5123 // Methods for the mutator alloc region
5124 
5125 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5126                                                       bool force) {
5127   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5128   bool should_allocate = g1_policy()->should_allocate_mutator_region();
5129   if (force || should_allocate) {
5130     HeapRegion* new_alloc_region = new_region(word_size,
5131                                               false /* is_old */,
5132                                               false /* do_expand */);
5133     if (new_alloc_region != NULL) {
5134       set_region_short_lived_locked(new_alloc_region);
5135       _hr_printer.alloc(new_alloc_region, !should_allocate);
5136       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5137       return new_alloc_region;
5138     }
5139   }
5140   return NULL;
5141 }
5142 
5143 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5144                                                   size_t allocated_bytes) {
5145   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5146   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5147 
5148   collection_set()->add_eden_region(alloc_region);
5149   increase_used(allocated_bytes);
5150   _hr_printer.retire(alloc_region);
5151   // We update the eden sizes here, when the region is retired,
5152   // instead of when it's allocated, since this is the point that its
5153   // used space has been recored in _summary_bytes_used.
5154   g1mm()->update_eden_size();
5155 }
5156 
5157 // Methods for the GC alloc regions
5158 
5159 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5160   if (dest.is_old()) {
5161     return true;
5162   } else {
5163     return survivor_regions_count() < g1_policy()->max_survivor_regions();
5164   }
5165 }
5166 
5167 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5168   assert(FreeList_lock->owned_by_self(), "pre-condition");
5169 
5170   if (!has_more_regions(dest)) {
5171     return NULL;
5172   }
5173 
5174   const bool is_survivor = dest.is_young();
5175 
5176   HeapRegion* new_alloc_region = new_region(word_size,
5177                                             !is_survivor,
5178                                             true /* do_expand */);
5179   if (new_alloc_region != NULL) {
5180     // We really only need to do this for old regions given that we
5181     // should never scan survivors. But it doesn't hurt to do it
5182     // for survivors too.
5183     new_alloc_region->record_timestamp();
5184     if (is_survivor) {
5185       new_alloc_region->set_survivor();
5186       _survivor.add(new_alloc_region);
5187       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5188     } else {
5189       new_alloc_region->set_old();
5190       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5191     }
5192     _hr_printer.alloc(new_alloc_region);
5193     bool during_im = collector_state()->during_initial_mark_pause();
5194     new_alloc_region->note_start_of_copying(during_im);
5195     return new_alloc_region;
5196   }
5197   return NULL;
5198 }
5199 
5200 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5201                                              size_t allocated_bytes,
5202                                              InCSetState dest) {
5203   bool during_im = collector_state()->during_initial_mark_pause();
5204   alloc_region->note_end_of_copying(during_im);
5205   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5206   if (dest.is_old()) {
5207     _old_set.add(alloc_region);
5208   }
5209   _hr_printer.retire(alloc_region);
5210 }
5211 
5212 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5213   bool expanded = false;
5214   uint index = _hrm.find_highest_free(&expanded);
5215 
5216   if (index != G1_NO_HRM_INDEX) {
5217     if (expanded) {
5218       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5219                                 HeapRegion::GrainWords * HeapWordSize);
5220     }
5221     _hrm.allocate_free_regions_starting_at(index, 1);
5222     return region_at(index);
5223   }
5224   return NULL;
5225 }
5226 
5227 // Optimized nmethod scanning
5228 
5229 class RegisterNMethodOopClosure: public OopClosure {
5230   G1CollectedHeap* _g1h;
5231   nmethod* _nm;
5232 
5233   template <class T> void do_oop_work(T* p) {
5234     T heap_oop = oopDesc::load_heap_oop(p);
5235     if (!oopDesc::is_null(heap_oop)) {
5236       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5237       HeapRegion* hr = _g1h->heap_region_containing(obj);
5238       assert(!hr->is_continues_humongous(),
5239              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5240              " starting at " HR_FORMAT,
5241              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5242 
5243       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5244       hr->add_strong_code_root_locked(_nm);
5245     }
5246   }
5247 
5248 public:
5249   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5250     _g1h(g1h), _nm(nm) {}
5251 
5252   void do_oop(oop* p)       { do_oop_work(p); }
5253   void do_oop(narrowOop* p) { do_oop_work(p); }
5254 };
5255 
5256 class UnregisterNMethodOopClosure: public OopClosure {
5257   G1CollectedHeap* _g1h;
5258   nmethod* _nm;
5259 
5260   template <class T> void do_oop_work(T* p) {
5261     T heap_oop = oopDesc::load_heap_oop(p);
5262     if (!oopDesc::is_null(heap_oop)) {
5263       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5264       HeapRegion* hr = _g1h->heap_region_containing(obj);
5265       assert(!hr->is_continues_humongous(),
5266              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5267              " starting at " HR_FORMAT,
5268              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5269 
5270       hr->remove_strong_code_root(_nm);
5271     }
5272   }
5273 
5274 public:
5275   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5276     _g1h(g1h), _nm(nm) {}
5277 
5278   void do_oop(oop* p)       { do_oop_work(p); }
5279   void do_oop(narrowOop* p) { do_oop_work(p); }
5280 };
5281 
5282 // Returns true if the reference points to an object that
5283 // can move in an incremental collection.
5284 bool G1CollectedHeap::is_scavengable(oop obj) {
5285   HeapRegion* hr = heap_region_containing(obj);
5286   return !hr->is_pinned();
5287 }
5288 
5289 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5290   guarantee(nm != NULL, "sanity");
5291   RegisterNMethodOopClosure reg_cl(this, nm);
5292   nm->oops_do(&reg_cl);
5293 }
5294 
5295 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5296   guarantee(nm != NULL, "sanity");
5297   UnregisterNMethodOopClosure reg_cl(this, nm);
5298   nm->oops_do(&reg_cl, true);
5299 }
5300 
5301 void G1CollectedHeap::purge_code_root_memory() {
5302   double purge_start = os::elapsedTime();
5303   G1CodeRootSet::purge();
5304   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5305   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5306 }
5307 
5308 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5309   G1CollectedHeap* _g1h;
5310 
5311 public:
5312   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5313     _g1h(g1h) {}
5314 
5315   void do_code_blob(CodeBlob* cb) {
5316     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5317     if (nm == NULL) {
5318       return;
5319     }
5320 
5321     if (ScavengeRootsInCode) {
5322       _g1h->register_nmethod(nm);
5323     }
5324   }
5325 };
5326 
5327 void G1CollectedHeap::rebuild_strong_code_roots() {
5328   RebuildStrongCodeRootClosure blob_cl(this);
5329   CodeCache::blobs_do(&blob_cl);
5330 }
5331 
5332 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5333   GrowableArray<GCMemoryManager*> memory_managers(2);
5334   memory_managers.append(&_memory_manager);
5335   memory_managers.append(&_full_gc_memory_manager);
5336   return memory_managers;
5337 }
5338 
5339 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5340   GrowableArray<MemoryPool*> memory_pools(3);
5341   memory_pools.append(_eden_pool);
5342   memory_pools.append(_survivor_pool);
5343   memory_pools.append(_old_pool);
5344   return memory_pools;
5345 }