1 /*
   2  * Copyright (c) 2001, 2017, 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   uint dummy_gc_count_before;
 449   uint dummy_gclocker_retry_count = 0;
 450   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 451 }
 452 
 453 HeapWord*
 454 G1CollectedHeap::mem_allocate(size_t word_size,
 455                               bool*  gc_overhead_limit_was_exceeded) {
 456   assert_heap_not_locked_and_not_at_safepoint();
 457 
 458   // Loop until the allocation is satisfied, or unsatisfied after GC.
 459   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 460     uint gc_count_before;
 461 
 462     HeapWord* result = NULL;
 463     if (!is_humongous(word_size)) {
 464       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 465     } else {
 466       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 467     }
 468     if (result != NULL) {
 469       return result;
 470     }
 471 
 472     // Create the garbage collection operation...
 473     VM_G1CollectForAllocation op(gc_count_before, word_size);
 474     op.set_allocation_context(AllocationContext::current());
 475 
 476     // ...and get the VM thread to execute it.
 477     VMThread::execute(&op);
 478 
 479     if (op.prologue_succeeded() && op.pause_succeeded()) {
 480       // If the operation was successful we'll return the result even
 481       // if it is NULL. If the allocation attempt failed immediately
 482       // after a Full GC, it's unlikely we'll be able to allocate now.
 483       HeapWord* result = op.result();
 484       if (result != NULL && !is_humongous(word_size)) {
 485         // Allocations that take place on VM operations do not do any
 486         // card dirtying and we have to do it here. We only have to do
 487         // this for non-humongous allocations, though.
 488         dirty_young_block(result, word_size);
 489       }
 490       return result;
 491     } else {
 492       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 493         return NULL;
 494       }
 495       assert(op.result() == NULL,
 496              "the result should be NULL if the VM op did not succeed");
 497     }
 498 
 499     // Give a warning if we seem to be looping forever.
 500     if ((QueuedAllocationWarningCount > 0) &&
 501         (try_count % QueuedAllocationWarningCount == 0)) {
 502       log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
 503     }
 504   }
 505 
 506   ShouldNotReachHere();
 507   return NULL;
 508 }
 509 
 510 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 511                                                    AllocationContext_t context,
 512                                                    uint* gc_count_before_ret,
 513                                                    uint* gclocker_retry_count_ret) {
 514   // Make sure you read the note in attempt_allocation_humongous().
 515 
 516   assert_heap_not_locked_and_not_at_safepoint();
 517   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 518          "be called for humongous allocation requests");
 519 
 520   // We should only get here after the first-level allocation attempt
 521   // (attempt_allocation()) failed to allocate.
 522 
 523   // We will loop until a) we manage to successfully perform the
 524   // allocation or b) we successfully schedule a collection which
 525   // fails to perform the allocation. b) is the only case when we'll
 526   // return NULL.
 527   HeapWord* result = NULL;
 528   for (int try_count = 1; /* we'll return */; try_count += 1) {
 529     bool should_try_gc;
 530     uint gc_count_before;
 531 
 532     {
 533       MutexLockerEx x(Heap_lock);
 534       result = _allocator->attempt_allocation_locked(word_size, context);
 535       if (result != NULL) {
 536         return result;
 537       }
 538 
 539       if (GCLocker::is_active_and_needs_gc()) {
 540         if (g1_policy()->can_expand_young_list()) {
 541           // No need for an ergo verbose message here,
 542           // can_expand_young_list() does this when it returns true.
 543           result = _allocator->attempt_allocation_force(word_size, context);
 544           if (result != NULL) {
 545             return result;
 546           }
 547         }
 548         should_try_gc = false;
 549       } else {
 550         // The GCLocker may not be active but the GCLocker initiated
 551         // GC may not yet have been performed (GCLocker::needs_gc()
 552         // returns true). In this case we do not try this GC and
 553         // wait until the GCLocker initiated GC is performed, and
 554         // then retry the allocation.
 555         if (GCLocker::needs_gc()) {
 556           should_try_gc = false;
 557         } else {
 558           // Read the GC count while still holding the Heap_lock.
 559           gc_count_before = total_collections();
 560           should_try_gc = true;
 561         }
 562       }
 563     }
 564 
 565     if (should_try_gc) {
 566       bool succeeded;
 567       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 568                                    GCCause::_g1_inc_collection_pause);
 569       if (result != NULL) {
 570         assert(succeeded, "only way to get back a non-NULL result");
 571         return result;
 572       }
 573 
 574       if (succeeded) {
 575         // If we get here we successfully scheduled a collection which
 576         // failed to allocate. No point in trying to allocate
 577         // further. We'll just return NULL.
 578         MutexLockerEx x(Heap_lock);
 579         *gc_count_before_ret = total_collections();
 580         return NULL;
 581       }
 582     } else {
 583       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 584         MutexLockerEx x(Heap_lock);
 585         *gc_count_before_ret = total_collections();
 586         return NULL;
 587       }
 588       // The GCLocker is either active or the GCLocker initiated
 589       // GC has not yet been performed. Stall until it is and
 590       // then retry the allocation.
 591       GCLocker::stall_until_clear();
 592       (*gclocker_retry_count_ret) += 1;
 593     }
 594 
 595     // We can reach here if we were unsuccessful in scheduling a
 596     // collection (because another thread beat us to it) or if we were
 597     // stalled due to the GC locker. In either can we should retry the
 598     // allocation attempt in case another thread successfully
 599     // performed a collection and reclaimed enough space. We do the
 600     // first attempt (without holding the Heap_lock) here and the
 601     // follow-on attempt will be at the start of the next loop
 602     // iteration (after taking the Heap_lock).
 603     result = _allocator->attempt_allocation(word_size, context);
 604     if (result != NULL) {
 605       return result;
 606     }
 607 
 608     // Give a warning if we seem to be looping forever.
 609     if ((QueuedAllocationWarningCount > 0) &&
 610         (try_count % QueuedAllocationWarningCount == 0)) {
 611       log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
 612                       "retries %d times", try_count);
 613     }
 614   }
 615 
 616   ShouldNotReachHere();
 617   return NULL;
 618 }
 619 
 620 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 621   assert_at_safepoint(true /* should_be_vm_thread */);
 622   if (_archive_allocator == NULL) {
 623     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 624   }
 625 }
 626 
 627 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 628   // Allocations in archive regions cannot be of a size that would be considered
 629   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 630   // may be different at archive-restore time.
 631   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 632 }
 633 
 634 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 635   assert_at_safepoint(true /* should_be_vm_thread */);
 636   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 637   if (is_archive_alloc_too_large(word_size)) {
 638     return NULL;
 639   }
 640   return _archive_allocator->archive_mem_allocate(word_size);
 641 }
 642 
 643 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 644                                               size_t end_alignment_in_bytes) {
 645   assert_at_safepoint(true /* should_be_vm_thread */);
 646   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 647 
 648   // Call complete_archive to do the real work, filling in the MemRegion
 649   // array with the archive regions.
 650   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 651   delete _archive_allocator;
 652   _archive_allocator = NULL;
 653 }
 654 
 655 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 656   assert(ranges != NULL, "MemRegion array NULL");
 657   assert(count != 0, "No MemRegions provided");
 658   MemRegion reserved = _hrm.reserved();
 659   for (size_t i = 0; i < count; i++) {
 660     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 661       return false;
 662     }
 663   }
 664   return true;
 665 }
 666 
 667 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 668                                             size_t count,
 669                                             bool open) {
 670   assert(!is_init_completed(), "Expect to be called at JVM init time");
 671   assert(ranges != NULL, "MemRegion array NULL");
 672   assert(count != 0, "No MemRegions provided");
 673   MutexLockerEx x(Heap_lock);
 674 
 675   MemRegion reserved = _hrm.reserved();
 676   HeapWord* prev_last_addr = NULL;
 677   HeapRegion* prev_last_region = NULL;
 678 
 679   // Temporarily disable pretouching of heap pages. This interface is used
 680   // when mmap'ing archived heap data in, so pre-touching is wasted.
 681   FlagSetting fs(AlwaysPreTouch, false);
 682 
 683   // Enable archive object checking used by G1MarkSweep. We have to let it know
 684   // about each archive range, so that objects in those ranges aren't marked.
 685   G1ArchiveAllocator::enable_archive_object_check();
 686 
 687   // For each specified MemRegion range, allocate the corresponding G1
 688   // regions and mark them as archive regions. We expect the ranges
 689   // in ascending starting address order, without overlap.
 690   for (size_t i = 0; i < count; i++) {
 691     MemRegion curr_range = ranges[i];
 692     HeapWord* start_address = curr_range.start();
 693     size_t word_size = curr_range.word_size();
 694     HeapWord* last_address = curr_range.last();
 695     size_t commits = 0;
 696 
 697     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 698               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 699               p2i(start_address), p2i(last_address));
 700     guarantee(start_address > prev_last_addr,
 701               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 702               p2i(start_address), p2i(prev_last_addr));
 703     prev_last_addr = last_address;
 704 
 705     // Check for ranges that start in the same G1 region in which the previous
 706     // range ended, and adjust the start address so we don't try to allocate
 707     // the same region again. If the current range is entirely within that
 708     // region, skip it, just adjusting the recorded top.
 709     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 710     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 711       start_address = start_region->end();
 712       if (start_address > last_address) {
 713         increase_used(word_size * HeapWordSize);
 714         start_region->set_top(last_address + 1);
 715         continue;
 716       }
 717       start_region->set_top(start_address);
 718       curr_range = MemRegion(start_address, last_address + 1);
 719       start_region = _hrm.addr_to_region(start_address);
 720     }
 721 
 722     // Perform the actual region allocation, exiting if it fails.
 723     // Then note how much new space we have allocated.
 724     if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
 725       return false;
 726     }
 727     increase_used(word_size * HeapWordSize);
 728     if (commits != 0) {
 729       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 730                                 HeapRegion::GrainWords * HeapWordSize * commits);
 731 
 732     }
 733 
 734     // Mark each G1 region touched by the range as archive, add it to
 735     // the old set, and set the allocation context and top.
 736     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 737     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 738     prev_last_region = last_region;
 739 
 740     while (curr_region != NULL) {
 741       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 742              "Region already in use (index %u)", curr_region->hrm_index());
 743       curr_region->set_allocation_context(AllocationContext::system());
 744       if (open) {
 745         curr_region->set_open_archive();
 746       } else {
 747         curr_region->set_closed_archive();
 748       }
 749       _hr_printer.alloc(curr_region);
 750       _old_set.add(curr_region);
 751       HeapWord* top;
 752       HeapRegion* next_region;
 753       if (curr_region != last_region) {
 754         top = curr_region->end();
 755         next_region = _hrm.next_region_in_heap(curr_region);
 756       } else {
 757         top = last_address + 1;
 758         next_region = NULL;
 759       }
 760       curr_region->set_top(top);
 761       curr_region->set_first_dead(top);
 762       curr_region->set_end_of_live(top);
 763       curr_region = next_region;
 764     }
 765 
 766     // Notify mark-sweep of the archive
 767     G1ArchiveAllocator::set_range_archive(curr_range, open);
 768   }
 769   return true;
 770 }
 771 
 772 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 773   assert(!is_init_completed(), "Expect to be called at JVM init time");
 774   assert(ranges != NULL, "MemRegion array NULL");
 775   assert(count != 0, "No MemRegions provided");
 776   MemRegion reserved = _hrm.reserved();
 777   HeapWord *prev_last_addr = NULL;
 778   HeapRegion* prev_last_region = NULL;
 779 
 780   // For each MemRegion, create filler objects, if needed, in the G1 regions
 781   // that contain the address range. The address range actually within the
 782   // MemRegion will not be modified. That is assumed to have been initialized
 783   // elsewhere, probably via an mmap of archived heap data.
 784   MutexLockerEx x(Heap_lock);
 785   for (size_t i = 0; i < count; i++) {
 786     HeapWord* start_address = ranges[i].start();
 787     HeapWord* last_address = ranges[i].last();
 788 
 789     assert(reserved.contains(start_address) && reserved.contains(last_address),
 790            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 791            p2i(start_address), p2i(last_address));
 792     assert(start_address > prev_last_addr,
 793            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 794            p2i(start_address), p2i(prev_last_addr));
 795 
 796     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 797     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 798     HeapWord* bottom_address = start_region->bottom();
 799 
 800     // Check for a range beginning in the same region in which the
 801     // previous one ended.
 802     if (start_region == prev_last_region) {
 803       bottom_address = prev_last_addr + 1;
 804     }
 805 
 806     // Verify that the regions were all marked as archive regions by
 807     // alloc_archive_regions.
 808     HeapRegion* curr_region = start_region;
 809     while (curr_region != NULL) {
 810       guarantee(curr_region->is_archive(),
 811                 "Expected archive region at index %u", curr_region->hrm_index());
 812       if (curr_region != last_region) {
 813         curr_region = _hrm.next_region_in_heap(curr_region);
 814       } else {
 815         curr_region = NULL;
 816       }
 817     }
 818 
 819     prev_last_addr = last_address;
 820     prev_last_region = last_region;
 821 
 822     // Fill the memory below the allocated range with dummy object(s),
 823     // if the region bottom does not match the range start, or if the previous
 824     // range ended within the same G1 region, and there is a gap.
 825     if (start_address != bottom_address) {
 826       size_t fill_size = pointer_delta(start_address, bottom_address);
 827       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 828       increase_used(fill_size * HeapWordSize);
 829     }
 830   }
 831 }
 832 
 833 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
 834                                                      uint* gc_count_before_ret,
 835                                                      uint* gclocker_retry_count_ret) {
 836   assert_heap_not_locked_and_not_at_safepoint();
 837   assert(!is_humongous(word_size), "attempt_allocation() should not "
 838          "be called for humongous allocation requests");
 839 
 840   AllocationContext_t context = AllocationContext::current();
 841   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 842 
 843   if (result == NULL) {
 844     result = attempt_allocation_slow(word_size,
 845                                      context,
 846                                      gc_count_before_ret,
 847                                      gclocker_retry_count_ret);
 848   }
 849   assert_heap_not_locked();
 850   if (result != NULL) {
 851     dirty_young_block(result, word_size);
 852   }
 853   return result;
 854 }
 855 
 856 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 857   assert(!is_init_completed(), "Expect to be called at JVM init time");
 858   assert(ranges != NULL, "MemRegion array NULL");
 859   assert(count != 0, "No MemRegions provided");
 860   MemRegion reserved = _hrm.reserved();
 861   HeapWord* prev_last_addr = NULL;
 862   HeapRegion* prev_last_region = NULL;
 863   size_t size_used = 0;
 864   size_t uncommitted_regions = 0;
 865 
 866   // For each Memregion, free the G1 regions that constitute it, and
 867   // notify mark-sweep that the range is no longer to be considered 'archive.'
 868   MutexLockerEx x(Heap_lock);
 869   for (size_t i = 0; i < count; i++) {
 870     HeapWord* start_address = ranges[i].start();
 871     HeapWord* last_address = ranges[i].last();
 872 
 873     assert(reserved.contains(start_address) && reserved.contains(last_address),
 874            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 875            p2i(start_address), p2i(last_address));
 876     assert(start_address > prev_last_addr,
 877            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 878            p2i(start_address), p2i(prev_last_addr));
 879     size_used += ranges[i].byte_size();
 880     prev_last_addr = last_address;
 881 
 882     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 883     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 884 
 885     // Check for ranges that start in the same G1 region in which the previous
 886     // range ended, and adjust the start address so we don't try to free
 887     // the same region again. If the current range is entirely within that
 888     // region, skip it.
 889     if (start_region == prev_last_region) {
 890       start_address = start_region->end();
 891       if (start_address > last_address) {
 892         continue;
 893       }
 894       start_region = _hrm.addr_to_region(start_address);
 895     }
 896     prev_last_region = last_region;
 897 
 898     // After verifying that each region was marked as an archive region by
 899     // alloc_archive_regions, set it free and empty and uncommit it.
 900     HeapRegion* curr_region = start_region;
 901     while (curr_region != NULL) {
 902       guarantee(curr_region->is_archive(),
 903                 "Expected archive region at index %u", curr_region->hrm_index());
 904       uint curr_index = curr_region->hrm_index();
 905       _old_set.remove(curr_region);
 906       curr_region->set_free();
 907       curr_region->set_top(curr_region->bottom());
 908       if (curr_region != last_region) {
 909         curr_region = _hrm.next_region_in_heap(curr_region);
 910       } else {
 911         curr_region = NULL;
 912       }
 913       _hrm.shrink_at(curr_index, 1);
 914       uncommitted_regions++;
 915     }
 916 
 917     // Notify mark-sweep that this is no longer an archive range.
 918     G1ArchiveAllocator::set_range_archive(ranges[i], false);
 919   }
 920 
 921   if (uncommitted_regions != 0) {
 922     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 923                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 924   }
 925   decrease_used(size_used);
 926 }
 927 
 928 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 929                                                         uint* gc_count_before_ret,
 930                                                         uint* gclocker_retry_count_ret) {
 931   // The structure of this method has a lot of similarities to
 932   // attempt_allocation_slow(). The reason these two were not merged
 933   // into a single one is that such a method would require several "if
 934   // allocation is not humongous do this, otherwise do that"
 935   // conditional paths which would obscure its flow. In fact, an early
 936   // version of this code did use a unified method which was harder to
 937   // follow and, as a result, it had subtle bugs that were hard to
 938   // track down. So keeping these two methods separate allows each to
 939   // be more readable. It will be good to keep these two in sync as
 940   // much as possible.
 941 
 942   assert_heap_not_locked_and_not_at_safepoint();
 943   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 944          "should only be called for humongous allocations");
 945 
 946   // Humongous objects can exhaust the heap quickly, so we should check if we
 947   // need to start a marking cycle at each humongous object allocation. We do
 948   // the check before we do the actual allocation. The reason for doing it
 949   // before the allocation is that we avoid having to keep track of the newly
 950   // allocated memory while we do a GC.
 951   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 952                                            word_size)) {
 953     collect(GCCause::_g1_humongous_allocation);
 954   }
 955 
 956   // We will loop until a) we manage to successfully perform the
 957   // allocation or b) we successfully schedule a collection which
 958   // fails to perform the allocation. b) is the only case when we'll
 959   // return NULL.
 960   HeapWord* result = NULL;
 961   for (int try_count = 1; /* we'll return */; try_count += 1) {
 962     bool should_try_gc;
 963     uint gc_count_before;
 964 
 965     {
 966       MutexLockerEx x(Heap_lock);
 967 
 968       // Given that humongous objects are not allocated in young
 969       // regions, we'll first try to do the allocation without doing a
 970       // collection hoping that there's enough space in the heap.
 971       result = humongous_obj_allocate(word_size, AllocationContext::current());
 972       if (result != NULL) {
 973         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 974         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 975         return result;
 976       }
 977 
 978       if (GCLocker::is_active_and_needs_gc()) {
 979         should_try_gc = false;
 980       } else {
 981          // The GCLocker may not be active but the GCLocker initiated
 982         // GC may not yet have been performed (GCLocker::needs_gc()
 983         // returns true). In this case we do not try this GC and
 984         // wait until the GCLocker initiated GC is performed, and
 985         // then retry the allocation.
 986         if (GCLocker::needs_gc()) {
 987           should_try_gc = false;
 988         } else {
 989           // Read the GC count while still holding the Heap_lock.
 990           gc_count_before = total_collections();
 991           should_try_gc = true;
 992         }
 993       }
 994     }
 995 
 996     if (should_try_gc) {
 997       // If we failed to allocate the humongous object, we should try to
 998       // do a collection pause (if we're allowed) in case it reclaims
 999       // enough space for the allocation to succeed after the pause.
1000 
1001       bool succeeded;
1002       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1003                                    GCCause::_g1_humongous_allocation);
1004       if (result != NULL) {
1005         assert(succeeded, "only way to get back a non-NULL result");
1006         return result;
1007       }
1008 
1009       if (succeeded) {
1010         // If we get here we successfully scheduled a collection which
1011         // failed to allocate. No point in trying to allocate
1012         // further. We'll just return NULL.
1013         MutexLockerEx x(Heap_lock);
1014         *gc_count_before_ret = total_collections();
1015         return NULL;
1016       }
1017     } else {
1018       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1019         MutexLockerEx x(Heap_lock);
1020         *gc_count_before_ret = total_collections();
1021         return NULL;
1022       }
1023       // The GCLocker is either active or the GCLocker initiated
1024       // GC has not yet been performed. Stall until it is and
1025       // then retry the allocation.
1026       GCLocker::stall_until_clear();
1027       (*gclocker_retry_count_ret) += 1;
1028     }
1029 
1030     // We can reach here if we were unsuccessful in scheduling a
1031     // collection (because another thread beat us to it) or if we were
1032     // stalled due to the GC locker. In either can we should retry the
1033     // allocation attempt in case another thread successfully
1034     // performed a collection and reclaimed enough space.  Give a
1035     // warning if we seem to be looping forever.
1036 
1037     if ((QueuedAllocationWarningCount > 0) &&
1038         (try_count % QueuedAllocationWarningCount == 0)) {
1039       log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1040                       "retries %d times", try_count);
1041     }
1042   }
1043 
1044   ShouldNotReachHere();
1045   return NULL;
1046 }
1047 
1048 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1049                                                            AllocationContext_t context,
1050                                                            bool expect_null_mutator_alloc_region) {
1051   assert_at_safepoint(true /* should_be_vm_thread */);
1052   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1053          "the current alloc region was unexpectedly found to be non-NULL");
1054 
1055   if (!is_humongous(word_size)) {
1056     return _allocator->attempt_allocation_locked(word_size, context);
1057   } else {
1058     HeapWord* result = humongous_obj_allocate(word_size, context);
1059     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1060       collector_state()->set_initiate_conc_mark_if_possible(true);
1061     }
1062     return result;
1063   }
1064 
1065   ShouldNotReachHere();
1066 }
1067 
1068 class PostCompactionPrinterClosure: public HeapRegionClosure {
1069 private:
1070   G1HRPrinter* _hr_printer;
1071 public:
1072   bool doHeapRegion(HeapRegion* hr) {
1073     assert(!hr->is_young(), "not expecting to find young regions");
1074     _hr_printer->post_compaction(hr);
1075     return false;
1076   }
1077 
1078   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1079     : _hr_printer(hr_printer) { }
1080 };
1081 
1082 void G1CollectedHeap::print_hrm_post_compaction() {
1083   if (_hr_printer.is_active()) {
1084     PostCompactionPrinterClosure cl(hr_printer());
1085     heap_region_iterate(&cl);
1086   }
1087 
1088 }
1089 
1090 void G1CollectedHeap::abort_concurrent_cycle() {
1091   // Note: When we have a more flexible GC logging framework that
1092   // allows us to add optional attributes to a GC log record we
1093   // could consider timing and reporting how long we wait in the
1094   // following two methods.
1095   wait_while_free_regions_coming();
1096   // If we start the compaction before the CM threads finish
1097   // scanning the root regions we might trip them over as we'll
1098   // be moving objects / updating references. So let's wait until
1099   // they are done. By telling them to abort, they should complete
1100   // early.
1101   _cm->root_regions()->abort();
1102   _cm->root_regions()->wait_until_scan_finished();
1103   append_secondary_free_list_if_not_empty_with_lock();
1104 
1105   // Disable discovery and empty the discovered lists
1106   // for the CM ref processor.
1107   ref_processor_cm()->disable_discovery();
1108   ref_processor_cm()->abandon_partial_discovery();
1109   ref_processor_cm()->verify_no_references_recorded();
1110 
1111   // Abandon current iterations of concurrent marking and concurrent
1112   // refinement, if any are in progress.
1113   concurrent_mark()->abort();
1114 }
1115 
1116 void G1CollectedHeap::prepare_heap_for_full_collection() {
1117   // Make sure we'll choose a new allocation region afterwards.
1118   _allocator->release_mutator_alloc_region();
1119   _allocator->abandon_gc_alloc_regions();
1120   g1_rem_set()->cleanupHRRS();
1121 
1122   // We may have added regions to the current incremental collection
1123   // set between the last GC or pause and now. We need to clear the
1124   // incremental collection set and then start rebuilding it afresh
1125   // after this full GC.
1126   abandon_collection_set(collection_set());
1127 
1128   tear_down_region_sets(false /* free_list_only */);
1129   collector_state()->set_gcs_are_young(true);
1130 }
1131 
1132 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1133   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1134   assert(used() == recalculate_used(), "Should be equal");
1135   _verifier->verify_region_sets_optional();
1136   _verifier->verify_before_gc();
1137   _verifier->check_bitmaps("Full GC Start");
1138 }
1139 
1140 void G1CollectedHeap::prepare_heap_for_mutators() {
1141   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1142   ClassLoaderDataGraph::purge();
1143   MetaspaceAux::verify_metrics();
1144 
1145   // Prepare heap for normal collections.
1146   assert(num_free_regions() == 0, "we should not have added any free regions");
1147   rebuild_region_sets(false /* free_list_only */);
1148   abort_refinement();
1149   resize_if_necessary_after_full_collection();
1150 
1151   // Rebuild the strong code root lists for each region
1152   rebuild_strong_code_roots();
1153 
1154   // Start a new incremental collection set for the next pause
1155   start_new_collection_set();
1156 
1157   _allocator->init_mutator_alloc_region();
1158 
1159   // Post collection state updates.
1160   MetaspaceGC::compute_new_size();
1161 }
1162 
1163 void G1CollectedHeap::abort_refinement() {
1164   if (_hot_card_cache->use_cache()) {
1165     _hot_card_cache->reset_hot_cache();
1166   }
1167 
1168   // Discard all remembered set updates.
1169   JavaThread::dirty_card_queue_set().abandon_logs();
1170   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1171 }
1172 
1173 void G1CollectedHeap::verify_after_full_collection() {
1174   check_gc_time_stamps();
1175   _hrm.verify_optional();
1176   _verifier->verify_region_sets_optional();
1177   _verifier->verify_after_gc();
1178   // Clear the previous marking bitmap, if needed for bitmap verification.
1179   // Note we cannot do this when we clear the next marking bitmap in
1180   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1181   // objects marked during a full GC against the previous bitmap.
1182   // But we need to clear it before calling check_bitmaps below since
1183   // the full GC has compacted objects and updated TAMS but not updated
1184   // the prev bitmap.
1185   if (G1VerifyBitmaps) {
1186     GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1187     _cm->clear_prev_bitmap(workers());
1188   }
1189   _verifier->check_bitmaps("Full GC End");
1190 
1191   // At this point there should be no regions in the
1192   // entire heap tagged as young.
1193   assert(check_young_list_empty(), "young list should be empty at this point");
1194 
1195   // Note: since we've just done a full GC, concurrent
1196   // marking is no longer active. Therefore we need not
1197   // re-enable reference discovery for the CM ref processor.
1198   // That will be done at the start of the next marking cycle.
1199   // We also know that the STW processor should no longer
1200   // discover any new references.
1201   assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1202   assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1203   ref_processor_stw()->verify_no_references_recorded();
1204   ref_processor_cm()->verify_no_references_recorded();
1205 }
1206 
1207 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1208   // Post collection logging.
1209   // We should do this after we potentially resize the heap so
1210   // that all the COMMIT / UNCOMMIT events are generated before
1211   // the compaction events.
1212   print_hrm_post_compaction();
1213   heap_transition->print();
1214   print_heap_after_gc();
1215   print_heap_regions();
1216 #ifdef TRACESPINNING
1217   ParallelTaskTerminator::print_termination_counts();
1218 #endif
1219 }
1220 
1221 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1222                                          bool clear_all_soft_refs) {
1223   assert_at_safepoint(true /* should_be_vm_thread */);
1224 
1225   if (GCLocker::check_active_before_gc()) {
1226     // Full GC was not completed.
1227     return false;
1228   }
1229 
1230   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1231       collector_policy()->should_clear_all_soft_refs();
1232 
1233   G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1234   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1235 
1236   collector.prepare_collection();
1237   collector.collect();
1238   collector.complete_collection();
1239 
1240   // Full collection was successfully completed.
1241   return true;
1242 }
1243 
1244 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1245   // Currently, there is no facility in the do_full_collection(bool) API to notify
1246   // the caller that the collection did not succeed (e.g., because it was locked
1247   // out by the GC locker). So, right now, we'll ignore the return value.
1248   bool dummy = do_full_collection(true,                /* explicit_gc */
1249                                   clear_all_soft_refs);
1250 }
1251 
1252 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1253   // Capacity, free and used after the GC counted as full regions to
1254   // include the waste in the following calculations.
1255   const size_t capacity_after_gc = capacity();
1256   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1257 
1258   // This is enforced in arguments.cpp.
1259   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1260          "otherwise the code below doesn't make sense");
1261 
1262   // We don't have floating point command-line arguments
1263   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1264   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1265   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1266   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1267 
1268   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1269   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1270 
1271   // We have to be careful here as these two calculations can overflow
1272   // 32-bit size_t's.
1273   double used_after_gc_d = (double) used_after_gc;
1274   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1275   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1276 
1277   // Let's make sure that they are both under the max heap size, which
1278   // by default will make them fit into a size_t.
1279   double desired_capacity_upper_bound = (double) max_heap_size;
1280   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1281                                     desired_capacity_upper_bound);
1282   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1283                                     desired_capacity_upper_bound);
1284 
1285   // We can now safely turn them into size_t's.
1286   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1287   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1288 
1289   // This assert only makes sense here, before we adjust them
1290   // with respect to the min and max heap size.
1291   assert(minimum_desired_capacity <= maximum_desired_capacity,
1292          "minimum_desired_capacity = " SIZE_FORMAT ", "
1293          "maximum_desired_capacity = " SIZE_FORMAT,
1294          minimum_desired_capacity, maximum_desired_capacity);
1295 
1296   // Should not be greater than the heap max size. No need to adjust
1297   // it with respect to the heap min size as it's a lower bound (i.e.,
1298   // we'll try to make the capacity larger than it, not smaller).
1299   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1300   // Should not be less than the heap min size. No need to adjust it
1301   // with respect to the heap max size as it's an upper bound (i.e.,
1302   // we'll try to make the capacity smaller than it, not greater).
1303   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1304 
1305   if (capacity_after_gc < minimum_desired_capacity) {
1306     // Don't expand unless it's significant
1307     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1308 
1309     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1310                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1311                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1312                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1313 
1314     expand(expand_bytes, _workers);
1315 
1316     // No expansion, now see if we want to shrink
1317   } else if (capacity_after_gc > maximum_desired_capacity) {
1318     // Capacity too large, compute shrinking size
1319     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1320 
1321     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1322                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1323                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1324                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1325 
1326     shrink(shrink_bytes);
1327   }
1328 }
1329 
1330 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1331                                                             AllocationContext_t context,
1332                                                             bool do_gc,
1333                                                             bool clear_all_soft_refs,
1334                                                             bool expect_null_mutator_alloc_region,
1335                                                             bool* gc_succeeded) {
1336   *gc_succeeded = true;
1337   // Let's attempt the allocation first.
1338   HeapWord* result =
1339     attempt_allocation_at_safepoint(word_size,
1340                                     context,
1341                                     expect_null_mutator_alloc_region);
1342   if (result != NULL) {
1343     assert(*gc_succeeded, "sanity");
1344     return result;
1345   }
1346 
1347   // In a G1 heap, we're supposed to keep allocation from failing by
1348   // incremental pauses.  Therefore, at least for now, we'll favor
1349   // expansion over collection.  (This might change in the future if we can
1350   // do something smarter than full collection to satisfy a failed alloc.)
1351   result = expand_and_allocate(word_size, context);
1352   if (result != NULL) {
1353     assert(*gc_succeeded, "sanity");
1354     return result;
1355   }
1356 
1357   if (do_gc) {
1358     // Expansion didn't work, we'll try to do a Full GC.
1359     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1360                                        clear_all_soft_refs);
1361   }
1362 
1363   return NULL;
1364 }
1365 
1366 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1367                                                      AllocationContext_t context,
1368                                                      bool* succeeded) {
1369   assert_at_safepoint(true /* should_be_vm_thread */);
1370 
1371   // Attempts to allocate followed by Full GC.
1372   HeapWord* result =
1373     satisfy_failed_allocation_helper(word_size,
1374                                      context,
1375                                      true,  /* do_gc */
1376                                      false, /* clear_all_soft_refs */
1377                                      false, /* expect_null_mutator_alloc_region */
1378                                      succeeded);
1379 
1380   if (result != NULL || !*succeeded) {
1381     return result;
1382   }
1383 
1384   // Attempts to allocate followed by Full GC that will collect all soft references.
1385   result = satisfy_failed_allocation_helper(word_size,
1386                                             context,
1387                                             true, /* do_gc */
1388                                             true, /* clear_all_soft_refs */
1389                                             true, /* expect_null_mutator_alloc_region */
1390                                             succeeded);
1391 
1392   if (result != NULL || !*succeeded) {
1393     return result;
1394   }
1395 
1396   // Attempts to allocate, no GC
1397   result = satisfy_failed_allocation_helper(word_size,
1398                                             context,
1399                                             false, /* do_gc */
1400                                             false, /* clear_all_soft_refs */
1401                                             true,  /* expect_null_mutator_alloc_region */
1402                                             succeeded);
1403 
1404   if (result != NULL) {
1405     assert(*succeeded, "sanity");
1406     return result;
1407   }
1408 
1409   assert(!collector_policy()->should_clear_all_soft_refs(),
1410          "Flag should have been handled and cleared prior to this point");
1411 
1412   // What else?  We might try synchronous finalization later.  If the total
1413   // space available is large enough for the allocation, then a more
1414   // complete compaction phase than we've tried so far might be
1415   // appropriate.
1416   assert(*succeeded, "sanity");
1417   return NULL;
1418 }
1419 
1420 // Attempting to expand the heap sufficiently
1421 // to support an allocation of the given "word_size".  If
1422 // successful, perform the allocation and return the address of the
1423 // allocated block, or else "NULL".
1424 
1425 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1426   assert_at_safepoint(true /* should_be_vm_thread */);
1427 
1428   _verifier->verify_region_sets_optional();
1429 
1430   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1431   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1432                             word_size * HeapWordSize);
1433 
1434 
1435   if (expand(expand_bytes, _workers)) {
1436     _hrm.verify_optional();
1437     _verifier->verify_region_sets_optional();
1438     return attempt_allocation_at_safepoint(word_size,
1439                                            context,
1440                                            false /* expect_null_mutator_alloc_region */);
1441   }
1442   return NULL;
1443 }
1444 
1445 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1446   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1447   aligned_expand_bytes = align_up(aligned_expand_bytes,
1448                                        HeapRegion::GrainBytes);
1449 
1450   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1451                             expand_bytes, aligned_expand_bytes);
1452 
1453   if (is_maximal_no_gc()) {
1454     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1455     return false;
1456   }
1457 
1458   double expand_heap_start_time_sec = os::elapsedTime();
1459   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1460   assert(regions_to_expand > 0, "Must expand by at least one region");
1461 
1462   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1463   if (expand_time_ms != NULL) {
1464     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1465   }
1466 
1467   if (expanded_by > 0) {
1468     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1469     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1470     g1_policy()->record_new_heap_size(num_regions());
1471   } else {
1472     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1473 
1474     // The expansion of the virtual storage space was unsuccessful.
1475     // Let's see if it was because we ran out of swap.
1476     if (G1ExitOnExpansionFailure &&
1477         _hrm.available() >= regions_to_expand) {
1478       // We had head room...
1479       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1480     }
1481   }
1482   return regions_to_expand > 0;
1483 }
1484 
1485 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1486   size_t aligned_shrink_bytes =
1487     ReservedSpace::page_align_size_down(shrink_bytes);
1488   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1489                                          HeapRegion::GrainBytes);
1490   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1491 
1492   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1493   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1494 
1495 
1496   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",
1497                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1498   if (num_regions_removed > 0) {
1499     g1_policy()->record_new_heap_size(num_regions());
1500   } else {
1501     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1502   }
1503 }
1504 
1505 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1506   _verifier->verify_region_sets_optional();
1507 
1508   // We should only reach here at the end of a Full GC which means we
1509   // should not not be holding to any GC alloc regions. The method
1510   // below will make sure of that and do any remaining clean up.
1511   _allocator->abandon_gc_alloc_regions();
1512 
1513   // Instead of tearing down / rebuilding the free lists here, we
1514   // could instead use the remove_all_pending() method on free_list to
1515   // remove only the ones that we need to remove.
1516   tear_down_region_sets(true /* free_list_only */);
1517   shrink_helper(shrink_bytes);
1518   rebuild_region_sets(true /* free_list_only */);
1519 
1520   _hrm.verify_optional();
1521   _verifier->verify_region_sets_optional();
1522 }
1523 
1524 // Public methods.
1525 
1526 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1527   CollectedHeap(),
1528   _young_gen_sampling_thread(NULL),
1529   _collector_policy(collector_policy),
1530   _memory_manager("G1 Young Generation", "end of minor GC"),
1531   _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1532   _eden_pool(NULL),
1533   _survivor_pool(NULL),
1534   _old_pool(NULL),
1535   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1536   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1537   _g1_policy(create_g1_policy(_gc_timer_stw)),
1538   _collection_set(this, _g1_policy),
1539   _dirty_card_queue_set(false),
1540   _is_alive_closure_cm(this),
1541   _is_alive_closure_stw(this),
1542   _ref_processor_cm(NULL),
1543   _ref_processor_stw(NULL),
1544   _bot(NULL),
1545   _hot_card_cache(NULL),
1546   _g1_rem_set(NULL),
1547   _cr(NULL),
1548   _g1mm(NULL),
1549   _preserved_marks_set(true /* in_c_heap */),
1550   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1551   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1552   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1553   _humongous_reclaim_candidates(),
1554   _has_humongous_reclaim_candidates(false),
1555   _archive_allocator(NULL),
1556   _free_regions_coming(false),
1557   _gc_time_stamp(0),
1558   _summary_bytes_used(0),
1559   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1560   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1561   _expand_heap_after_alloc_failure(true),
1562   _old_marking_cycles_started(0),
1563   _old_marking_cycles_completed(0),
1564   _in_cset_fast_test() {
1565 
1566   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1567                           /* are_GC_task_threads */true,
1568                           /* are_ConcurrentGC_threads */false);
1569   _workers->initialize_workers();
1570   _verifier = new G1HeapVerifier(this);
1571 
1572   _allocator = G1Allocator::create_allocator(this);
1573 
1574   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1575 
1576   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1577 
1578   // Override the default _filler_array_max_size so that no humongous filler
1579   // objects are created.
1580   _filler_array_max_size = _humongous_object_threshold_in_words;
1581 
1582   uint n_queues = ParallelGCThreads;
1583   _task_queues = new RefToScanQueueSet(n_queues);
1584 
1585   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1586 
1587   for (uint i = 0; i < n_queues; i++) {
1588     RefToScanQueue* q = new RefToScanQueue();
1589     q->initialize();
1590     _task_queues->register_queue(i, q);
1591     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1592   }
1593 
1594   // Initialize the G1EvacuationFailureALot counters and flags.
1595   NOT_PRODUCT(reset_evacuation_should_fail();)
1596 
1597   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1598 }
1599 
1600 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1601                                                                  size_t size,
1602                                                                  size_t translation_factor) {
1603   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1604   // Allocate a new reserved space, preferring to use large pages.
1605   ReservedSpace rs(size, preferred_page_size);
1606   G1RegionToSpaceMapper* result  =
1607     G1RegionToSpaceMapper::create_mapper(rs,
1608                                          size,
1609                                          rs.alignment(),
1610                                          HeapRegion::GrainBytes,
1611                                          translation_factor,
1612                                          mtGC);
1613 
1614   os::trace_page_sizes_for_requested_size(description,
1615                                           size,
1616                                           preferred_page_size,
1617                                           rs.alignment(),
1618                                           rs.base(),
1619                                           rs.size());
1620 
1621   return result;
1622 }
1623 
1624 jint G1CollectedHeap::initialize_concurrent_refinement() {
1625   jint ecode = JNI_OK;
1626   _cr = G1ConcurrentRefine::create(&ecode);
1627   return ecode;
1628 }
1629 
1630 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1631   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1632   if (_young_gen_sampling_thread->osthread() == NULL) {
1633     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1634     return JNI_ENOMEM;
1635   }
1636   return JNI_OK;
1637 }
1638 
1639 jint G1CollectedHeap::initialize() {
1640   CollectedHeap::pre_initialize();
1641   os::enable_vtime();
1642 
1643   // Necessary to satisfy locking discipline assertions.
1644 
1645   MutexLocker x(Heap_lock);
1646 
1647   // While there are no constraints in the GC code that HeapWordSize
1648   // be any particular value, there are multiple other areas in the
1649   // system which believe this to be true (e.g. oop->object_size in some
1650   // cases incorrectly returns the size in wordSize units rather than
1651   // HeapWordSize).
1652   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1653 
1654   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1655   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1656   size_t heap_alignment = collector_policy()->heap_alignment();
1657 
1658   // Ensure that the sizes are properly aligned.
1659   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1660   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1661   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1662 
1663   // Reserve the maximum.
1664 
1665   // When compressed oops are enabled, the preferred heap base
1666   // is calculated by subtracting the requested size from the
1667   // 32Gb boundary and using the result as the base address for
1668   // heap reservation. If the requested size is not aligned to
1669   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1670   // into the ReservedHeapSpace constructor) then the actual
1671   // base of the reserved heap may end up differing from the
1672   // address that was requested (i.e. the preferred heap base).
1673   // If this happens then we could end up using a non-optimal
1674   // compressed oops mode.
1675 
1676   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1677                                                  heap_alignment);
1678 
1679   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1680 
1681   // Create the barrier set for the entire reserved region.
1682   G1SATBCardTableLoggingModRefBS* bs
1683     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1684   bs->initialize();
1685   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1686   set_barrier_set(bs);
1687 
1688   // Create the hot card cache.
1689   _hot_card_cache = new G1HotCardCache(this);
1690 
1691   // Carve out the G1 part of the heap.
1692   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1693   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1694   G1RegionToSpaceMapper* heap_storage =
1695     G1RegionToSpaceMapper::create_mapper(g1_rs,
1696                                          g1_rs.size(),
1697                                          page_size,
1698                                          HeapRegion::GrainBytes,
1699                                          1,
1700                                          mtJavaHeap);
1701   os::trace_page_sizes("Heap",
1702                        collector_policy()->min_heap_byte_size(),
1703                        max_byte_size,
1704                        page_size,
1705                        heap_rs.base(),
1706                        heap_rs.size());
1707   heap_storage->set_mapping_changed_listener(&_listener);
1708 
1709   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1710   G1RegionToSpaceMapper* bot_storage =
1711     create_aux_memory_mapper("Block Offset Table",
1712                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1713                              G1BlockOffsetTable::heap_map_factor());
1714 
1715   G1RegionToSpaceMapper* cardtable_storage =
1716     create_aux_memory_mapper("Card Table",
1717                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1718                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1719 
1720   G1RegionToSpaceMapper* card_counts_storage =
1721     create_aux_memory_mapper("Card Counts Table",
1722                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1723                              G1CardCounts::heap_map_factor());
1724 
1725   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1726   G1RegionToSpaceMapper* prev_bitmap_storage =
1727     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1728   G1RegionToSpaceMapper* next_bitmap_storage =
1729     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1730 
1731   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1732   g1_barrier_set()->initialize(cardtable_storage);
1733   // Do later initialization work for concurrent refinement.
1734   _hot_card_cache->initialize(card_counts_storage);
1735 
1736   // 6843694 - ensure that the maximum region index can fit
1737   // in the remembered set structures.
1738   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1739   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1740 
1741   // Also create a G1 rem set.
1742   _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1743   _g1_rem_set->initialize(max_capacity(), max_regions());
1744 
1745   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1746   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1747   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1748             "too many cards per region");
1749 
1750   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1751 
1752   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1753 
1754   {
1755     HeapWord* start = _hrm.reserved().start();
1756     HeapWord* end = _hrm.reserved().end();
1757     size_t granularity = HeapRegion::GrainBytes;
1758 
1759     _in_cset_fast_test.initialize(start, end, granularity);
1760     _humongous_reclaim_candidates.initialize(start, end, granularity);
1761   }
1762 
1763   // Create the G1ConcurrentMark data structure and thread.
1764   // (Must do this late, so that "max_regions" is defined.)
1765   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1766   if (_cm == NULL || !_cm->completed_initialization()) {
1767     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1768     return JNI_ENOMEM;
1769   }
1770   _cmThread = _cm->cm_thread();
1771 
1772   // Now expand into the initial heap size.
1773   if (!expand(init_byte_size, _workers)) {
1774     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1775     return JNI_ENOMEM;
1776   }
1777 
1778   // Perform any initialization actions delegated to the policy.
1779   g1_policy()->init(this, &_collection_set);
1780 
1781   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1782                                                SATB_Q_FL_lock,
1783                                                G1SATBProcessCompletedThreshold,
1784                                                Shared_SATB_Q_lock);
1785 
1786   jint ecode = initialize_concurrent_refinement();
1787   if (ecode != JNI_OK) {
1788     return ecode;
1789   }
1790 
1791   ecode = initialize_young_gen_sampling_thread();
1792   if (ecode != JNI_OK) {
1793     return ecode;
1794   }
1795 
1796   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1797                                                 DirtyCardQ_FL_lock,
1798                                                 (int)concurrent_refine()->yellow_zone(),
1799                                                 (int)concurrent_refine()->red_zone(),
1800                                                 Shared_DirtyCardQ_lock,
1801                                                 NULL,  // fl_owner
1802                                                 true); // init_free_ids
1803 
1804   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1805                                     DirtyCardQ_FL_lock,
1806                                     -1, // never trigger processing
1807                                     -1, // no limit on length
1808                                     Shared_DirtyCardQ_lock,
1809                                     &JavaThread::dirty_card_queue_set());
1810 
1811   // Here we allocate the dummy HeapRegion that is required by the
1812   // G1AllocRegion class.
1813   HeapRegion* dummy_region = _hrm.get_dummy_region();
1814 
1815   // We'll re-use the same region whether the alloc region will
1816   // require BOT updates or not and, if it doesn't, then a non-young
1817   // region will complain that it cannot support allocations without
1818   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1819   dummy_region->set_eden();
1820   // Make sure it's full.
1821   dummy_region->set_top(dummy_region->end());
1822   G1AllocRegion::setup(this, dummy_region);
1823 
1824   _allocator->init_mutator_alloc_region();
1825 
1826   // Do create of the monitoring and management support so that
1827   // values in the heap have been properly initialized.
1828   _g1mm = new G1MonitoringSupport(this);
1829 
1830   G1StringDedup::initialize();
1831 
1832   _preserved_marks_set.init(ParallelGCThreads);
1833 
1834   _collection_set.initialize(max_regions());
1835 
1836   return JNI_OK;
1837 }
1838 
1839 void G1CollectedHeap::initialize_serviceability() {
1840   _eden_pool = new G1EdenPool(this);
1841   _survivor_pool = new G1SurvivorPool(this);
1842   _old_pool = new G1OldGenPool(this);
1843 
1844   _full_gc_memory_manager.add_pool(_eden_pool);
1845   _full_gc_memory_manager.add_pool(_survivor_pool);
1846   _full_gc_memory_manager.add_pool(_old_pool);
1847 
1848   _memory_manager.add_pool(_eden_pool);
1849   _memory_manager.add_pool(_survivor_pool);
1850 
1851 }
1852 
1853 void G1CollectedHeap::stop() {
1854   // Stop all concurrent threads. We do this to make sure these threads
1855   // do not continue to execute and access resources (e.g. logging)
1856   // that are destroyed during shutdown.
1857   _cr->stop();
1858   _young_gen_sampling_thread->stop();
1859   _cmThread->stop();
1860   if (G1StringDedup::is_enabled()) {
1861     G1StringDedup::stop();
1862   }
1863 }
1864 
1865 void G1CollectedHeap::safepoint_synchronize_begin() {
1866   SuspendibleThreadSet::synchronize();
1867 }
1868 
1869 void G1CollectedHeap::safepoint_synchronize_end() {
1870   SuspendibleThreadSet::desynchronize();
1871 }
1872 
1873 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1874   return HeapRegion::max_region_size();
1875 }
1876 
1877 void G1CollectedHeap::post_initialize() {
1878   CollectedHeap::post_initialize();
1879   ref_processing_init();
1880 }
1881 
1882 void G1CollectedHeap::ref_processing_init() {
1883   // Reference processing in G1 currently works as follows:
1884   //
1885   // * There are two reference processor instances. One is
1886   //   used to record and process discovered references
1887   //   during concurrent marking; the other is used to
1888   //   record and process references during STW pauses
1889   //   (both full and incremental).
1890   // * Both ref processors need to 'span' the entire heap as
1891   //   the regions in the collection set may be dotted around.
1892   //
1893   // * For the concurrent marking ref processor:
1894   //   * Reference discovery is enabled at initial marking.
1895   //   * Reference discovery is disabled and the discovered
1896   //     references processed etc during remarking.
1897   //   * Reference discovery is MT (see below).
1898   //   * Reference discovery requires a barrier (see below).
1899   //   * Reference processing may or may not be MT
1900   //     (depending on the value of ParallelRefProcEnabled
1901   //     and ParallelGCThreads).
1902   //   * A full GC disables reference discovery by the CM
1903   //     ref processor and abandons any entries on it's
1904   //     discovered lists.
1905   //
1906   // * For the STW processor:
1907   //   * Non MT discovery is enabled at the start of a full GC.
1908   //   * Processing and enqueueing during a full GC is non-MT.
1909   //   * During a full GC, references are processed after marking.
1910   //
1911   //   * Discovery (may or may not be MT) is enabled at the start
1912   //     of an incremental evacuation pause.
1913   //   * References are processed near the end of a STW evacuation pause.
1914   //   * For both types of GC:
1915   //     * Discovery is atomic - i.e. not concurrent.
1916   //     * Reference discovery will not need a barrier.
1917 
1918   MemRegion mr = reserved_region();
1919 
1920   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1921 
1922   // Concurrent Mark ref processor
1923   _ref_processor_cm =
1924     new ReferenceProcessor(mr,    // span
1925                            mt_processing,
1926                                 // mt processing
1927                            ParallelGCThreads,
1928                                 // degree of mt processing
1929                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1930                                 // mt discovery
1931                            MAX2(ParallelGCThreads, ConcGCThreads),
1932                                 // degree of mt discovery
1933                            false,
1934                                 // Reference discovery is not atomic
1935                            &_is_alive_closure_cm);
1936                                 // is alive closure
1937                                 // (for efficiency/performance)
1938 
1939   // STW ref processor
1940   _ref_processor_stw =
1941     new ReferenceProcessor(mr,    // span
1942                            mt_processing,
1943                                 // mt processing
1944                            ParallelGCThreads,
1945                                 // degree of mt processing
1946                            (ParallelGCThreads > 1),
1947                                 // mt discovery
1948                            ParallelGCThreads,
1949                                 // degree of mt discovery
1950                            true,
1951                                 // Reference discovery is atomic
1952                            &_is_alive_closure_stw);
1953                                 // is alive closure
1954                                 // (for efficiency/performance)
1955 }
1956 
1957 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1958   return _collector_policy;
1959 }
1960 
1961 size_t G1CollectedHeap::capacity() const {
1962   return _hrm.length() * HeapRegion::GrainBytes;
1963 }
1964 
1965 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1966   return _hrm.total_free_bytes();
1967 }
1968 
1969 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1970   hr->reset_gc_time_stamp();
1971 }
1972 
1973 #ifndef PRODUCT
1974 
1975 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1976 private:
1977   unsigned _gc_time_stamp;
1978   bool _failures;
1979 
1980 public:
1981   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1982     _gc_time_stamp(gc_time_stamp), _failures(false) { }
1983 
1984   virtual bool doHeapRegion(HeapRegion* hr) {
1985     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1986     if (_gc_time_stamp != region_gc_time_stamp) {
1987       log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1988                             region_gc_time_stamp, _gc_time_stamp);
1989       _failures = true;
1990     }
1991     return false;
1992   }
1993 
1994   bool failures() { return _failures; }
1995 };
1996 
1997 void G1CollectedHeap::check_gc_time_stamps() {
1998   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1999   heap_region_iterate(&cl);
2000   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2001 }
2002 #endif // PRODUCT
2003 
2004 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2005   _hot_card_cache->drain(cl, worker_i);
2006 }
2007 
2008 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2009   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2010   size_t n_completed_buffers = 0;
2011   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
2012     n_completed_buffers++;
2013   }
2014   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2015   dcqs.clear_n_completed_buffers();
2016   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2017 }
2018 
2019 // Computes the sum of the storage used by the various regions.
2020 size_t G1CollectedHeap::used() const {
2021   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2022   if (_archive_allocator != NULL) {
2023     result += _archive_allocator->used();
2024   }
2025   return result;
2026 }
2027 
2028 size_t G1CollectedHeap::used_unlocked() const {
2029   return _summary_bytes_used;
2030 }
2031 
2032 class SumUsedClosure: public HeapRegionClosure {
2033   size_t _used;
2034 public:
2035   SumUsedClosure() : _used(0) {}
2036   bool doHeapRegion(HeapRegion* r) {
2037     _used += r->used();
2038     return false;
2039   }
2040   size_t result() { return _used; }
2041 };
2042 
2043 size_t G1CollectedHeap::recalculate_used() const {
2044   double recalculate_used_start = os::elapsedTime();
2045 
2046   SumUsedClosure blk;
2047   heap_region_iterate(&blk);
2048 
2049   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2050   return blk.result();
2051 }
2052 
2053 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2054   switch (cause) {
2055     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2056     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2057     case GCCause::_update_allocation_context_stats_inc: return true;
2058     case GCCause::_wb_conc_mark:                        return true;
2059     default :                                           return false;
2060   }
2061 }
2062 
2063 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2064   switch (cause) {
2065     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2066     case GCCause::_g1_humongous_allocation: return true;
2067     default:                                return is_user_requested_concurrent_full_gc(cause);
2068   }
2069 }
2070 
2071 #ifndef PRODUCT
2072 void G1CollectedHeap::allocate_dummy_regions() {
2073   // Let's fill up most of the region
2074   size_t word_size = HeapRegion::GrainWords - 1024;
2075   // And as a result the region we'll allocate will be humongous.
2076   guarantee(is_humongous(word_size), "sanity");
2077 
2078   // _filler_array_max_size is set to humongous object threshold
2079   // but temporarily change it to use CollectedHeap::fill_with_object().
2080   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2081 
2082   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2083     // Let's use the existing mechanism for the allocation
2084     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2085                                                  AllocationContext::system());
2086     if (dummy_obj != NULL) {
2087       MemRegion mr(dummy_obj, word_size);
2088       CollectedHeap::fill_with_object(mr);
2089     } else {
2090       // If we can't allocate once, we probably cannot allocate
2091       // again. Let's get out of the loop.
2092       break;
2093     }
2094   }
2095 }
2096 #endif // !PRODUCT
2097 
2098 void G1CollectedHeap::increment_old_marking_cycles_started() {
2099   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2100          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2101          "Wrong marking cycle count (started: %d, completed: %d)",
2102          _old_marking_cycles_started, _old_marking_cycles_completed);
2103 
2104   _old_marking_cycles_started++;
2105 }
2106 
2107 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2108   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2109 
2110   // We assume that if concurrent == true, then the caller is a
2111   // concurrent thread that was joined the Suspendible Thread
2112   // Set. If there's ever a cheap way to check this, we should add an
2113   // assert here.
2114 
2115   // Given that this method is called at the end of a Full GC or of a
2116   // concurrent cycle, and those can be nested (i.e., a Full GC can
2117   // interrupt a concurrent cycle), the number of full collections
2118   // completed should be either one (in the case where there was no
2119   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2120   // behind the number of full collections started.
2121 
2122   // This is the case for the inner caller, i.e. a Full GC.
2123   assert(concurrent ||
2124          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2125          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2126          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2127          "is inconsistent with _old_marking_cycles_completed = %u",
2128          _old_marking_cycles_started, _old_marking_cycles_completed);
2129 
2130   // This is the case for the outer caller, i.e. the concurrent cycle.
2131   assert(!concurrent ||
2132          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2133          "for outer caller (concurrent cycle): "
2134          "_old_marking_cycles_started = %u "
2135          "is inconsistent with _old_marking_cycles_completed = %u",
2136          _old_marking_cycles_started, _old_marking_cycles_completed);
2137 
2138   _old_marking_cycles_completed += 1;
2139 
2140   // We need to clear the "in_progress" flag in the CM thread before
2141   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2142   // is set) so that if a waiter requests another System.gc() it doesn't
2143   // incorrectly see that a marking cycle is still in progress.
2144   if (concurrent) {
2145     _cmThread->set_idle();
2146   }
2147 
2148   // This notify_all() will ensure that a thread that called
2149   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2150   // and it's waiting for a full GC to finish will be woken up. It is
2151   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2152   FullGCCount_lock->notify_all();
2153 }
2154 
2155 void G1CollectedHeap::collect(GCCause::Cause cause) {
2156   assert_heap_not_locked();
2157 
2158   uint gc_count_before;
2159   uint old_marking_count_before;
2160   uint full_gc_count_before;
2161   bool retry_gc;
2162 
2163   do {
2164     retry_gc = false;
2165 
2166     {
2167       MutexLocker ml(Heap_lock);
2168 
2169       // Read the GC count while holding the Heap_lock
2170       gc_count_before = total_collections();
2171       full_gc_count_before = total_full_collections();
2172       old_marking_count_before = _old_marking_cycles_started;
2173     }
2174 
2175     if (should_do_concurrent_full_gc(cause)) {
2176       // Schedule an initial-mark evacuation pause that will start a
2177       // concurrent cycle. We're setting word_size to 0 which means that
2178       // we are not requesting a post-GC allocation.
2179       VM_G1IncCollectionPause op(gc_count_before,
2180                                  0,     /* word_size */
2181                                  true,  /* should_initiate_conc_mark */
2182                                  g1_policy()->max_pause_time_ms(),
2183                                  cause);
2184       op.set_allocation_context(AllocationContext::current());
2185 
2186       VMThread::execute(&op);
2187       if (!op.pause_succeeded()) {
2188         if (old_marking_count_before == _old_marking_cycles_started) {
2189           retry_gc = op.should_retry_gc();
2190         } else {
2191           // A Full GC happened while we were trying to schedule the
2192           // initial-mark GC. No point in starting a new cycle given
2193           // that the whole heap was collected anyway.
2194         }
2195 
2196         if (retry_gc) {
2197           if (GCLocker::is_active_and_needs_gc()) {
2198             GCLocker::stall_until_clear();
2199           }
2200         }
2201       }
2202     } else {
2203       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2204           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2205 
2206         // Schedule a standard evacuation pause. We're setting word_size
2207         // to 0 which means that we are not requesting a post-GC allocation.
2208         VM_G1IncCollectionPause op(gc_count_before,
2209                                    0,     /* word_size */
2210                                    false, /* should_initiate_conc_mark */
2211                                    g1_policy()->max_pause_time_ms(),
2212                                    cause);
2213         VMThread::execute(&op);
2214       } else {
2215         // Schedule a Full GC.
2216         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2217         VMThread::execute(&op);
2218       }
2219     }
2220   } while (retry_gc);
2221 }
2222 
2223 bool G1CollectedHeap::is_in(const void* p) const {
2224   if (_hrm.reserved().contains(p)) {
2225     // Given that we know that p is in the reserved space,
2226     // heap_region_containing() should successfully
2227     // return the containing region.
2228     HeapRegion* hr = heap_region_containing(p);
2229     return hr->is_in(p);
2230   } else {
2231     return false;
2232   }
2233 }
2234 
2235 #ifdef ASSERT
2236 bool G1CollectedHeap::is_in_exact(const void* p) const {
2237   bool contains = reserved_region().contains(p);
2238   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2239   if (contains && available) {
2240     return true;
2241   } else {
2242     return false;
2243   }
2244 }
2245 #endif
2246 
2247 // Iteration functions.
2248 
2249 // Iterates an ObjectClosure over all objects within a HeapRegion.
2250 
2251 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2252   ObjectClosure* _cl;
2253 public:
2254   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2255   bool doHeapRegion(HeapRegion* r) {
2256     if (!r->is_continues_humongous()) {
2257       r->object_iterate(_cl);
2258     }
2259     return false;
2260   }
2261 };
2262 
2263 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2264   IterateObjectClosureRegionClosure blk(cl);
2265   heap_region_iterate(&blk);
2266 }
2267 
2268 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2269   _hrm.iterate(cl);
2270 }
2271 
2272 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2273                                                                  HeapRegionClaimer *hrclaimer,
2274                                                                  uint worker_id) const {
2275   _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2276 }
2277 
2278 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2279                                                          HeapRegionClaimer *hrclaimer) const {
2280   _hrm.par_iterate(cl, hrclaimer, 0);
2281 }
2282 
2283 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2284   _collection_set.iterate(cl);
2285 }
2286 
2287 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2288   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2289 }
2290 
2291 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2292   HeapRegion* hr = heap_region_containing(addr);
2293   return hr->block_start(addr);
2294 }
2295 
2296 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2297   HeapRegion* hr = heap_region_containing(addr);
2298   return hr->block_size(addr);
2299 }
2300 
2301 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2302   HeapRegion* hr = heap_region_containing(addr);
2303   return hr->block_is_obj(addr);
2304 }
2305 
2306 bool G1CollectedHeap::supports_tlab_allocation() const {
2307   return true;
2308 }
2309 
2310 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2311   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2312 }
2313 
2314 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2315   return _eden.length() * HeapRegion::GrainBytes;
2316 }
2317 
2318 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2319 // must be equal to the humongous object limit.
2320 size_t G1CollectedHeap::max_tlab_size() const {
2321   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2322 }
2323 
2324 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2325   AllocationContext_t context = AllocationContext::current();
2326   return _allocator->unsafe_max_tlab_alloc(context);
2327 }
2328 
2329 size_t G1CollectedHeap::max_capacity() const {
2330   return _hrm.reserved().byte_size();
2331 }
2332 
2333 jlong G1CollectedHeap::millis_since_last_gc() {
2334   // See the notes in GenCollectedHeap::millis_since_last_gc()
2335   // for more information about the implementation.
2336   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2337     _g1_policy->collection_pause_end_millis();
2338   if (ret_val < 0) {
2339     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2340       ". returning zero instead.", ret_val);
2341     return 0;
2342   }
2343   return ret_val;
2344 }
2345 
2346 void G1CollectedHeap::prepare_for_verify() {
2347   _verifier->prepare_for_verify();
2348 }
2349 
2350 void G1CollectedHeap::verify(VerifyOption vo) {
2351   _verifier->verify(vo);
2352 }
2353 
2354 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2355   return true;
2356 }
2357 
2358 const char* const* G1CollectedHeap::concurrent_phases() const {
2359   return _cmThread->concurrent_phases();
2360 }
2361 
2362 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2363   return _cmThread->request_concurrent_phase(phase);
2364 }
2365 
2366 class PrintRegionClosure: public HeapRegionClosure {
2367   outputStream* _st;
2368 public:
2369   PrintRegionClosure(outputStream* st) : _st(st) {}
2370   bool doHeapRegion(HeapRegion* r) {
2371     r->print_on(_st);
2372     return false;
2373   }
2374 };
2375 
2376 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2377                                        const HeapRegion* hr,
2378                                        const VerifyOption vo) const {
2379   switch (vo) {
2380   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2381   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2382   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2383   default:                            ShouldNotReachHere();
2384   }
2385   return false; // keep some compilers happy
2386 }
2387 
2388 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2389                                        const VerifyOption vo) const {
2390   switch (vo) {
2391   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2392   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2393   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2394   default:                            ShouldNotReachHere();
2395   }
2396   return false; // keep some compilers happy
2397 }
2398 
2399 void G1CollectedHeap::print_heap_regions() const {
2400   LogTarget(Trace, gc, heap, region) lt;
2401   if (lt.is_enabled()) {
2402     LogStream ls(lt);
2403     print_regions_on(&ls);
2404   }
2405 }
2406 
2407 void G1CollectedHeap::print_on(outputStream* st) const {
2408   st->print(" %-20s", "garbage-first heap");
2409   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2410             capacity()/K, used_unlocked()/K);
2411   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2412             p2i(_hrm.reserved().start()),
2413             p2i(_hrm.reserved().end()));
2414   st->cr();
2415   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2416   uint young_regions = young_regions_count();
2417   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2418             (size_t) young_regions * HeapRegion::GrainBytes / K);
2419   uint survivor_regions = survivor_regions_count();
2420   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2421             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2422   st->cr();
2423   MetaspaceAux::print_on(st);
2424 }
2425 
2426 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2427   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2428                "HS=humongous(starts), HC=humongous(continues), "
2429                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2430                "AC=allocation context, "
2431                "TAMS=top-at-mark-start (previous, next)");
2432   PrintRegionClosure blk(st);
2433   heap_region_iterate(&blk);
2434 }
2435 
2436 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2437   print_on(st);
2438 
2439   // Print the per-region information.
2440   print_regions_on(st);
2441 }
2442 
2443 void G1CollectedHeap::print_on_error(outputStream* st) const {
2444   this->CollectedHeap::print_on_error(st);
2445 
2446   if (_cm != NULL) {
2447     st->cr();
2448     _cm->print_on_error(st);
2449   }
2450 }
2451 
2452 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2453   workers()->print_worker_threads_on(st);
2454   _cmThread->print_on(st);
2455   st->cr();
2456   _cm->print_worker_threads_on(st);
2457   _cr->print_threads_on(st);
2458   _young_gen_sampling_thread->print_on(st);
2459   if (G1StringDedup::is_enabled()) {
2460     G1StringDedup::print_worker_threads_on(st);
2461   }
2462 }
2463 
2464 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2465   workers()->threads_do(tc);
2466   tc->do_thread(_cmThread);
2467   _cm->threads_do(tc);
2468   _cr->threads_do(tc);
2469   tc->do_thread(_young_gen_sampling_thread);
2470   if (G1StringDedup::is_enabled()) {
2471     G1StringDedup::threads_do(tc);
2472   }
2473 }
2474 
2475 void G1CollectedHeap::print_tracing_info() const {
2476   g1_rem_set()->print_summary_info();
2477   concurrent_mark()->print_summary_info();
2478 }
2479 
2480 #ifndef PRODUCT
2481 // Helpful for debugging RSet issues.
2482 
2483 class PrintRSetsClosure : public HeapRegionClosure {
2484 private:
2485   const char* _msg;
2486   size_t _occupied_sum;
2487 
2488 public:
2489   bool doHeapRegion(HeapRegion* r) {
2490     HeapRegionRemSet* hrrs = r->rem_set();
2491     size_t occupied = hrrs->occupied();
2492     _occupied_sum += occupied;
2493 
2494     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2495     if (occupied == 0) {
2496       tty->print_cr("  RSet is empty");
2497     } else {
2498       hrrs->print();
2499     }
2500     tty->print_cr("----------");
2501     return false;
2502   }
2503 
2504   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2505     tty->cr();
2506     tty->print_cr("========================================");
2507     tty->print_cr("%s", msg);
2508     tty->cr();
2509   }
2510 
2511   ~PrintRSetsClosure() {
2512     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2513     tty->print_cr("========================================");
2514     tty->cr();
2515   }
2516 };
2517 
2518 void G1CollectedHeap::print_cset_rsets() {
2519   PrintRSetsClosure cl("Printing CSet RSets");
2520   collection_set_iterate(&cl);
2521 }
2522 
2523 void G1CollectedHeap::print_all_rsets() {
2524   PrintRSetsClosure cl("Printing All RSets");;
2525   heap_region_iterate(&cl);
2526 }
2527 #endif // PRODUCT
2528 
2529 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2530 
2531   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2532   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2533   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2534 
2535   size_t eden_capacity_bytes =
2536     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2537 
2538   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2539   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2540                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2541 }
2542 
2543 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2544   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2545                        stats->unused(), stats->used(), stats->region_end_waste(),
2546                        stats->regions_filled(), stats->direct_allocated(),
2547                        stats->failure_used(), stats->failure_waste());
2548 }
2549 
2550 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2551   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2552   gc_tracer->report_gc_heap_summary(when, heap_summary);
2553 
2554   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2555   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2556 }
2557 
2558 G1CollectedHeap* G1CollectedHeap::heap() {
2559   CollectedHeap* heap = Universe::heap();
2560   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2561   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2562   return (G1CollectedHeap*)heap;
2563 }
2564 
2565 void G1CollectedHeap::gc_prologue(bool full) {
2566   // always_do_update_barrier = false;
2567   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2568 
2569   // This summary needs to be printed before incrementing total collections.
2570   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2571 
2572   // Update common counters.
2573   increment_total_collections(full /* full gc */);
2574   if (full) {
2575     increment_old_marking_cycles_started();
2576     reset_gc_time_stamp();
2577   } else {
2578     increment_gc_time_stamp();
2579   }
2580 
2581   // Fill TLAB's and such
2582   double start = os::elapsedTime();
2583   accumulate_statistics_all_tlabs();
2584   ensure_parsability(true);
2585   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2586 }
2587 
2588 void G1CollectedHeap::gc_epilogue(bool full) {
2589   // Update common counters.
2590   if (full) {
2591     // Update the number of full collections that have been completed.
2592     increment_old_marking_cycles_completed(false /* concurrent */);
2593   }
2594 
2595   // We are at the end of the GC. Total collections has already been increased.
2596   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2597 
2598   // FIXME: what is this about?
2599   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2600   // is set.
2601 #if COMPILER2_OR_JVMCI
2602   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2603 #endif
2604   // always_do_update_barrier = true;
2605 
2606   double start = os::elapsedTime();
2607   resize_all_tlabs();
2608   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2609 
2610   allocation_context_stats().update(full);
2611 
2612   MemoryService::track_memory_usage();
2613   // We have just completed a GC. Update the soft reference
2614   // policy with the new heap occupancy
2615   Universe::update_heap_info_at_gc();
2616 }
2617 
2618 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2619                                                uint gc_count_before,
2620                                                bool* succeeded,
2621                                                GCCause::Cause gc_cause) {
2622   assert_heap_not_locked_and_not_at_safepoint();
2623   VM_G1IncCollectionPause op(gc_count_before,
2624                              word_size,
2625                              false, /* should_initiate_conc_mark */
2626                              g1_policy()->max_pause_time_ms(),
2627                              gc_cause);
2628 
2629   op.set_allocation_context(AllocationContext::current());
2630   VMThread::execute(&op);
2631 
2632   HeapWord* result = op.result();
2633   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2634   assert(result == NULL || ret_succeeded,
2635          "the result should be NULL if the VM did not succeed");
2636   *succeeded = ret_succeeded;
2637 
2638   assert_heap_not_locked();
2639   return result;
2640 }
2641 
2642 void
2643 G1CollectedHeap::doConcurrentMark() {
2644   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2645   if (!_cmThread->in_progress()) {
2646     _cmThread->set_started();
2647     CGC_lock->notify();
2648   }
2649 }
2650 
2651 size_t G1CollectedHeap::pending_card_num() {
2652   size_t extra_cards = 0;
2653   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2654     DirtyCardQueue& dcq = curr->dirty_card_queue();
2655     extra_cards += dcq.size();
2656   }
2657   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2658   size_t buffer_size = dcqs.buffer_size();
2659   size_t buffer_num = dcqs.completed_buffers_num();
2660 
2661   return buffer_size * buffer_num + extra_cards;
2662 }
2663 
2664 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2665  private:
2666   size_t _total_humongous;
2667   size_t _candidate_humongous;
2668 
2669   DirtyCardQueue _dcq;
2670 
2671   // We don't nominate objects with many remembered set entries, on
2672   // the assumption that such objects are likely still live.
2673   bool is_remset_small(HeapRegion* region) const {
2674     HeapRegionRemSet* const rset = region->rem_set();
2675     return G1EagerReclaimHumongousObjectsWithStaleRefs
2676       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2677       : rset->is_empty();
2678   }
2679 
2680   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2681     assert(region->is_starts_humongous(), "Must start a humongous object");
2682 
2683     oop obj = oop(region->bottom());
2684 
2685     // Dead objects cannot be eager reclaim candidates. Due to class
2686     // unloading it is unsafe to query their classes so we return early.
2687     if (heap->is_obj_dead(obj, region)) {
2688       return false;
2689     }
2690 
2691     // Candidate selection must satisfy the following constraints
2692     // while concurrent marking is in progress:
2693     //
2694     // * In order to maintain SATB invariants, an object must not be
2695     // reclaimed if it was allocated before the start of marking and
2696     // has not had its references scanned.  Such an object must have
2697     // its references (including type metadata) scanned to ensure no
2698     // live objects are missed by the marking process.  Objects
2699     // allocated after the start of concurrent marking don't need to
2700     // be scanned.
2701     //
2702     // * An object must not be reclaimed if it is on the concurrent
2703     // mark stack.  Objects allocated after the start of concurrent
2704     // marking are never pushed on the mark stack.
2705     //
2706     // Nominating only objects allocated after the start of concurrent
2707     // marking is sufficient to meet both constraints.  This may miss
2708     // some objects that satisfy the constraints, but the marking data
2709     // structures don't support efficiently performing the needed
2710     // additional tests or scrubbing of the mark stack.
2711     //
2712     // However, we presently only nominate is_typeArray() objects.
2713     // A humongous object containing references induces remembered
2714     // set entries on other regions.  In order to reclaim such an
2715     // object, those remembered sets would need to be cleaned up.
2716     //
2717     // We also treat is_typeArray() objects specially, allowing them
2718     // to be reclaimed even if allocated before the start of
2719     // concurrent mark.  For this we rely on mark stack insertion to
2720     // exclude is_typeArray() objects, preventing reclaiming an object
2721     // that is in the mark stack.  We also rely on the metadata for
2722     // such objects to be built-in and so ensured to be kept live.
2723     // Frequent allocation and drop of large binary blobs is an
2724     // important use case for eager reclaim, and this special handling
2725     // may reduce needed headroom.
2726 
2727     return obj->is_typeArray() && is_remset_small(region);
2728   }
2729 
2730  public:
2731   RegisterHumongousWithInCSetFastTestClosure()
2732   : _total_humongous(0),
2733     _candidate_humongous(0),
2734     _dcq(&JavaThread::dirty_card_queue_set()) {
2735   }
2736 
2737   virtual bool doHeapRegion(HeapRegion* r) {
2738     if (!r->is_starts_humongous()) {
2739       return false;
2740     }
2741     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2742 
2743     bool is_candidate = humongous_region_is_candidate(g1h, r);
2744     uint rindex = r->hrm_index();
2745     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2746     if (is_candidate) {
2747       _candidate_humongous++;
2748       g1h->register_humongous_region_with_cset(rindex);
2749       // Is_candidate already filters out humongous object with large remembered sets.
2750       // If we have a humongous object with a few remembered sets, we simply flush these
2751       // remembered set entries into the DCQS. That will result in automatic
2752       // re-evaluation of their remembered set entries during the following evacuation
2753       // phase.
2754       if (!r->rem_set()->is_empty()) {
2755         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2756                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2757         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2758         HeapRegionRemSetIterator hrrs(r->rem_set());
2759         size_t card_index;
2760         while (hrrs.has_next(card_index)) {
2761           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2762           // The remembered set might contain references to already freed
2763           // regions. Filter out such entries to avoid failing card table
2764           // verification.
2765           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2766             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2767               *card_ptr = CardTableModRefBS::dirty_card_val();
2768               _dcq.enqueue(card_ptr);
2769             }
2770           }
2771         }
2772         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2773                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2774                hrrs.n_yielded(), r->rem_set()->occupied());
2775         r->rem_set()->clear_locked();
2776       }
2777       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2778     }
2779     _total_humongous++;
2780 
2781     return false;
2782   }
2783 
2784   size_t total_humongous() const { return _total_humongous; }
2785   size_t candidate_humongous() const { return _candidate_humongous; }
2786 
2787   void flush_rem_set_entries() { _dcq.flush(); }
2788 };
2789 
2790 void G1CollectedHeap::register_humongous_regions_with_cset() {
2791   if (!G1EagerReclaimHumongousObjects) {
2792     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2793     return;
2794   }
2795   double time = os::elapsed_counter();
2796 
2797   // Collect reclaim candidate information and register candidates with cset.
2798   RegisterHumongousWithInCSetFastTestClosure cl;
2799   heap_region_iterate(&cl);
2800 
2801   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2802   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2803                                                                   cl.total_humongous(),
2804                                                                   cl.candidate_humongous());
2805   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2806 
2807   // Finally flush all remembered set entries to re-check into the global DCQS.
2808   cl.flush_rem_set_entries();
2809 }
2810 
2811 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2812   public:
2813     bool doHeapRegion(HeapRegion* hr) {
2814       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2815         hr->verify_rem_set();
2816       }
2817       return false;
2818     }
2819 };
2820 
2821 uint G1CollectedHeap::num_task_queues() const {
2822   return _task_queues->size();
2823 }
2824 
2825 #if TASKQUEUE_STATS
2826 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2827   st->print_raw_cr("GC Task Stats");
2828   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2829   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2830 }
2831 
2832 void G1CollectedHeap::print_taskqueue_stats() const {
2833   if (!log_is_enabled(Trace, gc, task, stats)) {
2834     return;
2835   }
2836   Log(gc, task, stats) log;
2837   ResourceMark rm;
2838   LogStream ls(log.trace());
2839   outputStream* st = &ls;
2840 
2841   print_taskqueue_stats_hdr(st);
2842 
2843   TaskQueueStats totals;
2844   const uint n = num_task_queues();
2845   for (uint i = 0; i < n; ++i) {
2846     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2847     totals += task_queue(i)->stats;
2848   }
2849   st->print_raw("tot "); totals.print(st); st->cr();
2850 
2851   DEBUG_ONLY(totals.verify());
2852 }
2853 
2854 void G1CollectedHeap::reset_taskqueue_stats() {
2855   const uint n = num_task_queues();
2856   for (uint i = 0; i < n; ++i) {
2857     task_queue(i)->stats.reset();
2858   }
2859 }
2860 #endif // TASKQUEUE_STATS
2861 
2862 void G1CollectedHeap::wait_for_root_region_scanning() {
2863   double scan_wait_start = os::elapsedTime();
2864   // We have to wait until the CM threads finish scanning the
2865   // root regions as it's the only way to ensure that all the
2866   // objects on them have been correctly scanned before we start
2867   // moving them during the GC.
2868   bool waited = _cm->root_regions()->wait_until_scan_finished();
2869   double wait_time_ms = 0.0;
2870   if (waited) {
2871     double scan_wait_end = os::elapsedTime();
2872     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2873   }
2874   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2875 }
2876 
2877 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2878 private:
2879   G1HRPrinter* _hr_printer;
2880 public:
2881   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2882 
2883   virtual bool doHeapRegion(HeapRegion* r) {
2884     _hr_printer->cset(r);
2885     return false;
2886   }
2887 };
2888 
2889 void G1CollectedHeap::start_new_collection_set() {
2890   collection_set()->start_incremental_building();
2891 
2892   clear_cset_fast_test();
2893 
2894   guarantee(_eden.length() == 0, "eden should have been cleared");
2895   g1_policy()->transfer_survivors_to_cset(survivor());
2896 }
2897 
2898 bool
2899 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2900   assert_at_safepoint(true /* should_be_vm_thread */);
2901   guarantee(!is_gc_active(), "collection is not reentrant");
2902 
2903   if (GCLocker::check_active_before_gc()) {
2904     return false;
2905   }
2906 
2907   _gc_timer_stw->register_gc_start();
2908 
2909   GCIdMark gc_id_mark;
2910   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2911 
2912   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2913   ResourceMark rm;
2914 
2915   g1_policy()->note_gc_start();
2916 
2917   wait_for_root_region_scanning();
2918 
2919   print_heap_before_gc();
2920   print_heap_regions();
2921   trace_heap_before_gc(_gc_tracer_stw);
2922 
2923   _verifier->verify_region_sets_optional();
2924   _verifier->verify_dirty_young_regions();
2925 
2926   // We should not be doing initial mark unless the conc mark thread is running
2927   if (!_cmThread->should_terminate()) {
2928     // This call will decide whether this pause is an initial-mark
2929     // pause. If it is, during_initial_mark_pause() will return true
2930     // for the duration of this pause.
2931     g1_policy()->decide_on_conc_mark_initiation();
2932   }
2933 
2934   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2935   assert(!collector_state()->during_initial_mark_pause() ||
2936           collector_state()->gcs_are_young(), "sanity");
2937 
2938   // We also do not allow mixed GCs during marking.
2939   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2940 
2941   // Record whether this pause is an initial mark. When the current
2942   // thread has completed its logging output and it's safe to signal
2943   // the CM thread, the flag's value in the policy has been reset.
2944   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2945 
2946   // Inner scope for scope based logging, timers, and stats collection
2947   {
2948     EvacuationInfo evacuation_info;
2949 
2950     if (collector_state()->during_initial_mark_pause()) {
2951       // We are about to start a marking cycle, so we increment the
2952       // full collection counter.
2953       increment_old_marking_cycles_started();
2954       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2955     }
2956 
2957     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2958 
2959     GCTraceCPUTime tcpu;
2960 
2961     FormatBuffer<> gc_string("Pause ");
2962     if (collector_state()->during_initial_mark_pause()) {
2963       gc_string.append("Initial Mark");
2964     } else if (collector_state()->gcs_are_young()) {
2965       gc_string.append("Young");
2966     } else {
2967       gc_string.append("Mixed");
2968     }
2969     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2970 
2971     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2972                                                                   workers()->active_workers(),
2973                                                                   Threads::number_of_non_daemon_threads());
2974     workers()->update_active_workers(active_workers);
2975     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2976 
2977     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2978     TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2979 
2980     // If the secondary_free_list is not empty, append it to the
2981     // free_list. No need to wait for the cleanup operation to finish;
2982     // the region allocation code will check the secondary_free_list
2983     // and wait if necessary. If the G1StressConcRegionFreeing flag is
2984     // set, skip this step so that the region allocation code has to
2985     // get entries from the secondary_free_list.
2986     if (!G1StressConcRegionFreeing) {
2987       append_secondary_free_list_if_not_empty_with_lock();
2988     }
2989 
2990     G1HeapTransition heap_transition(this);
2991     size_t heap_used_bytes_before_gc = used();
2992 
2993     // Don't dynamically change the number of GC threads this early.  A value of
2994     // 0 is used to indicate serial work.  When parallel work is done,
2995     // it will be set.
2996 
2997     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2998       IsGCActiveMark x;
2999 
3000       gc_prologue(false);
3001 
3002       if (VerifyRememberedSets) {
3003         log_info(gc, verify)("[Verifying RemSets before GC]");
3004         VerifyRegionRemSetClosure v_cl;
3005         heap_region_iterate(&v_cl);
3006       }
3007 
3008       _verifier->verify_before_gc();
3009 
3010       _verifier->check_bitmaps("GC Start");
3011 
3012 #if COMPILER2_OR_JVMCI
3013       DerivedPointerTable::clear();
3014 #endif
3015 
3016       // Please see comment in g1CollectedHeap.hpp and
3017       // G1CollectedHeap::ref_processing_init() to see how
3018       // reference processing currently works in G1.
3019 
3020       // Enable discovery in the STW reference processor
3021       if (g1_policy()->should_process_references()) {
3022         ref_processor_stw()->enable_discovery();
3023       } else {
3024         ref_processor_stw()->disable_discovery();
3025       }
3026 
3027       {
3028         // We want to temporarily turn off discovery by the
3029         // CM ref processor, if necessary, and turn it back on
3030         // on again later if we do. Using a scoped
3031         // NoRefDiscovery object will do this.
3032         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3033 
3034         // Forget the current alloc region (we might even choose it to be part
3035         // of the collection set!).
3036         _allocator->release_mutator_alloc_region();
3037 
3038         // This timing is only used by the ergonomics to handle our pause target.
3039         // It is unclear why this should not include the full pause. We will
3040         // investigate this in CR 7178365.
3041         //
3042         // Preserving the old comment here if that helps the investigation:
3043         //
3044         // The elapsed time induced by the start time below deliberately elides
3045         // the possible verification above.
3046         double sample_start_time_sec = os::elapsedTime();
3047 
3048         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3049 
3050         if (collector_state()->during_initial_mark_pause()) {
3051           concurrent_mark()->checkpoint_roots_initial_pre();
3052         }
3053 
3054         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3055 
3056         evacuation_info.set_collectionset_regions(collection_set()->region_length());
3057 
3058         // Make sure the remembered sets are up to date. This needs to be
3059         // done before register_humongous_regions_with_cset(), because the
3060         // remembered sets are used there to choose eager reclaim candidates.
3061         // If the remembered sets are not up to date we might miss some
3062         // entries that need to be handled.
3063         g1_rem_set()->cleanupHRRS();
3064 
3065         register_humongous_regions_with_cset();
3066 
3067         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3068 
3069         // We call this after finalize_cset() to
3070         // ensure that the CSet has been finalized.
3071         _cm->verify_no_cset_oops();
3072 
3073         if (_hr_printer.is_active()) {
3074           G1PrintCollectionSetClosure cl(&_hr_printer);
3075           _collection_set.iterate(&cl);
3076         }
3077 
3078         // Initialize the GC alloc regions.
3079         _allocator->init_gc_alloc_regions(evacuation_info);
3080 
3081         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3082         pre_evacuate_collection_set();
3083 
3084         // Actually do the work...
3085         evacuate_collection_set(evacuation_info, &per_thread_states);
3086 
3087         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3088 
3089         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3090         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3091 
3092         eagerly_reclaim_humongous_regions();
3093 
3094         record_obj_copy_mem_stats();
3095         _survivor_evac_stats.adjust_desired_plab_sz();
3096         _old_evac_stats.adjust_desired_plab_sz();
3097 
3098         double start = os::elapsedTime();
3099         start_new_collection_set();
3100         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3101 
3102         if (evacuation_failed()) {
3103           set_used(recalculate_used());
3104           if (_archive_allocator != NULL) {
3105             _archive_allocator->clear_used();
3106           }
3107           for (uint i = 0; i < ParallelGCThreads; i++) {
3108             if (_evacuation_failed_info_array[i].has_failed()) {
3109               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3110             }
3111           }
3112         } else {
3113           // The "used" of the the collection set have already been subtracted
3114           // when they were freed.  Add in the bytes evacuated.
3115           increase_used(g1_policy()->bytes_copied_during_gc());
3116         }
3117 
3118         if (collector_state()->during_initial_mark_pause()) {
3119           // We have to do this before we notify the CM threads that
3120           // they can start working to make sure that all the
3121           // appropriate initialization is done on the CM object.
3122           concurrent_mark()->checkpoint_roots_initial_post();
3123           collector_state()->set_mark_in_progress(true);
3124           // Note that we don't actually trigger the CM thread at
3125           // this point. We do that later when we're sure that
3126           // the current thread has completed its logging output.
3127         }
3128 
3129         allocate_dummy_regions();
3130 
3131         _allocator->init_mutator_alloc_region();
3132 
3133         {
3134           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3135           if (expand_bytes > 0) {
3136             size_t bytes_before = capacity();
3137             // No need for an ergo logging here,
3138             // expansion_amount() does this when it returns a value > 0.
3139             double expand_ms;
3140             if (!expand(expand_bytes, _workers, &expand_ms)) {
3141               // We failed to expand the heap. Cannot do anything about it.
3142             }
3143             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3144           }
3145         }
3146 
3147         // We redo the verification but now wrt to the new CSet which
3148         // has just got initialized after the previous CSet was freed.
3149         _cm->verify_no_cset_oops();
3150 
3151         // This timing is only used by the ergonomics to handle our pause target.
3152         // It is unclear why this should not include the full pause. We will
3153         // investigate this in CR 7178365.
3154         double sample_end_time_sec = os::elapsedTime();
3155         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3156         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3157         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3158 
3159         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3160         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3161 
3162         if (VerifyRememberedSets) {
3163           log_info(gc, verify)("[Verifying RemSets after GC]");
3164           VerifyRegionRemSetClosure v_cl;
3165           heap_region_iterate(&v_cl);
3166         }
3167 
3168         _verifier->verify_after_gc();
3169         _verifier->check_bitmaps("GC End");
3170 
3171         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3172         ref_processor_stw()->verify_no_references_recorded();
3173 
3174         // CM reference discovery will be re-enabled if necessary.
3175       }
3176 
3177 #ifdef TRACESPINNING
3178       ParallelTaskTerminator::print_termination_counts();
3179 #endif
3180 
3181       gc_epilogue(false);
3182     }
3183 
3184     // Print the remainder of the GC log output.
3185     if (evacuation_failed()) {
3186       log_info(gc)("To-space exhausted");
3187     }
3188 
3189     g1_policy()->print_phases();
3190     heap_transition.print();
3191 
3192     // It is not yet to safe to tell the concurrent mark to
3193     // start as we have some optional output below. We don't want the
3194     // output from the concurrent mark thread interfering with this
3195     // logging output either.
3196 
3197     _hrm.verify_optional();
3198     _verifier->verify_region_sets_optional();
3199 
3200     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3201     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3202 
3203     print_heap_after_gc();
3204     print_heap_regions();
3205     trace_heap_after_gc(_gc_tracer_stw);
3206 
3207     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3208     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3209     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3210     // before any GC notifications are raised.
3211     g1mm()->update_sizes();
3212 
3213     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3214     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3215     _gc_timer_stw->register_gc_end();
3216     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3217   }
3218   // It should now be safe to tell the concurrent mark thread to start
3219   // without its logging output interfering with the logging output
3220   // that came from the pause.
3221 
3222   if (should_start_conc_mark) {
3223     // CAUTION: after the doConcurrentMark() call below,
3224     // the concurrent marking thread(s) could be running
3225     // concurrently with us. Make sure that anything after
3226     // this point does not assume that we are the only GC thread
3227     // running. Note: of course, the actual marking work will
3228     // not start until the safepoint itself is released in
3229     // SuspendibleThreadSet::desynchronize().
3230     doConcurrentMark();
3231   }
3232 
3233   return true;
3234 }
3235 
3236 void G1CollectedHeap::remove_self_forwarding_pointers() {
3237   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3238   workers()->run_task(&rsfp_task);
3239 }
3240 
3241 void G1CollectedHeap::restore_after_evac_failure() {
3242   double remove_self_forwards_start = os::elapsedTime();
3243 
3244   remove_self_forwarding_pointers();
3245   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3246   _preserved_marks_set.restore(&task_executor);
3247 
3248   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3249 }
3250 
3251 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3252   if (!_evacuation_failed) {
3253     _evacuation_failed = true;
3254   }
3255 
3256   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3257   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3258 }
3259 
3260 bool G1ParEvacuateFollowersClosure::offer_termination() {
3261   G1ParScanThreadState* const pss = par_scan_state();
3262   start_term_time();
3263   const bool res = terminator()->offer_termination();
3264   end_term_time();
3265   return res;
3266 }
3267 
3268 void G1ParEvacuateFollowersClosure::do_void() {
3269   G1ParScanThreadState* const pss = par_scan_state();
3270   pss->trim_queue();
3271   do {
3272     pss->steal_and_trim_queue(queues());
3273   } while (!offer_termination());
3274 }
3275 
3276 class G1ParTask : public AbstractGangTask {
3277 protected:
3278   G1CollectedHeap*         _g1h;
3279   G1ParScanThreadStateSet* _pss;
3280   RefToScanQueueSet*       _queues;
3281   G1RootProcessor*         _root_processor;
3282   ParallelTaskTerminator   _terminator;
3283   uint                     _n_workers;
3284 
3285 public:
3286   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3287     : AbstractGangTask("G1 collection"),
3288       _g1h(g1h),
3289       _pss(per_thread_states),
3290       _queues(task_queues),
3291       _root_processor(root_processor),
3292       _terminator(n_workers, _queues),
3293       _n_workers(n_workers)
3294   {}
3295 
3296   void work(uint worker_id) {
3297     if (worker_id >= _n_workers) return;  // no work needed this round
3298 
3299     double start_sec = os::elapsedTime();
3300     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3301 
3302     {
3303       ResourceMark rm;
3304       HandleMark   hm;
3305 
3306       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3307 
3308       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3309       pss->set_ref_processor(rp);
3310 
3311       double start_strong_roots_sec = os::elapsedTime();
3312 
3313       _root_processor->evacuate_roots(pss->closures(), worker_id);
3314 
3315       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3316       // treating the nmethods visited to act as roots for concurrent marking.
3317       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3318       // objects copied by the current evacuation.
3319       _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3320                                                       pss->closures()->weak_codeblobs(),
3321                                                       worker_id);
3322 
3323       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3324 
3325       double term_sec = 0.0;
3326       size_t evac_term_attempts = 0;
3327       {
3328         double start = os::elapsedTime();
3329         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3330         evac.do_void();
3331 
3332         evac_term_attempts = evac.term_attempts();
3333         term_sec = evac.term_time();
3334         double elapsed_sec = os::elapsedTime() - start;
3335         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3336         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3337         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3338       }
3339 
3340       assert(pss->queue_is_empty(), "should be empty");
3341 
3342       if (log_is_enabled(Debug, gc, task, stats)) {
3343         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3344         size_t lab_waste;
3345         size_t lab_undo_waste;
3346         pss->waste(lab_waste, lab_undo_waste);
3347         _g1h->print_termination_stats(worker_id,
3348                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3349                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3350                                       term_sec * 1000.0,                          /* evac term time */
3351                                       evac_term_attempts,                         /* evac term attempts */
3352                                       lab_waste,                                  /* alloc buffer waste */
3353                                       lab_undo_waste                              /* undo waste */
3354                                       );
3355       }
3356 
3357       // Close the inner scope so that the ResourceMark and HandleMark
3358       // destructors are executed here and are included as part of the
3359       // "GC Worker Time".
3360     }
3361     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3362   }
3363 };
3364 
3365 void G1CollectedHeap::print_termination_stats_hdr() {
3366   log_debug(gc, task, stats)("GC Termination Stats");
3367   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3368   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3369   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3370 }
3371 
3372 void G1CollectedHeap::print_termination_stats(uint worker_id,
3373                                               double elapsed_ms,
3374                                               double strong_roots_ms,
3375                                               double term_ms,
3376                                               size_t term_attempts,
3377                                               size_t alloc_buffer_waste,
3378                                               size_t undo_waste) const {
3379   log_debug(gc, task, stats)
3380               ("%3d %9.2f %9.2f %6.2f "
3381                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3382                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3383                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3384                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3385                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3386                alloc_buffer_waste * HeapWordSize / K,
3387                undo_waste * HeapWordSize / K);
3388 }
3389 
3390 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3391 private:
3392   BoolObjectClosure* _is_alive;
3393   G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3394 
3395   int _initial_string_table_size;
3396   int _initial_symbol_table_size;
3397 
3398   bool  _process_strings;
3399   int _strings_processed;
3400   int _strings_removed;
3401 
3402   bool  _process_symbols;
3403   int _symbols_processed;
3404   int _symbols_removed;
3405 
3406   bool _process_string_dedup;
3407 
3408 public:
3409   G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3410     AbstractGangTask("String/Symbol Unlinking"),
3411     _is_alive(is_alive),
3412     _dedup_closure(is_alive, NULL, false),
3413     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3414     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3415     _process_string_dedup(process_string_dedup) {
3416 
3417     _initial_string_table_size = StringTable::the_table()->table_size();
3418     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3419     if (process_strings) {
3420       StringTable::clear_parallel_claimed_index();
3421     }
3422     if (process_symbols) {
3423       SymbolTable::clear_parallel_claimed_index();
3424     }
3425   }
3426 
3427   ~G1StringAndSymbolCleaningTask() {
3428     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3429               "claim value %d after unlink less than initial string table size %d",
3430               StringTable::parallel_claimed_index(), _initial_string_table_size);
3431     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3432               "claim value %d after unlink less than initial symbol table size %d",
3433               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3434 
3435     log_info(gc, stringtable)(
3436         "Cleaned string and symbol table, "
3437         "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3438         "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3439         strings_processed(), strings_removed(),
3440         symbols_processed(), symbols_removed());
3441   }
3442 
3443   void work(uint worker_id) {
3444     int strings_processed = 0;
3445     int strings_removed = 0;
3446     int symbols_processed = 0;
3447     int symbols_removed = 0;
3448     if (_process_strings) {
3449       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3450       Atomic::add(strings_processed, &_strings_processed);
3451       Atomic::add(strings_removed, &_strings_removed);
3452     }
3453     if (_process_symbols) {
3454       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3455       Atomic::add(symbols_processed, &_symbols_processed);
3456       Atomic::add(symbols_removed, &_symbols_removed);
3457     }
3458     if (_process_string_dedup) {
3459       G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3460     }
3461   }
3462 
3463   size_t strings_processed() const { return (size_t)_strings_processed; }
3464   size_t strings_removed()   const { return (size_t)_strings_removed; }
3465 
3466   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3467   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3468 };
3469 
3470 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3471 private:
3472   static Monitor* _lock;
3473 
3474   BoolObjectClosure* const _is_alive;
3475   const bool               _unloading_occurred;
3476   const uint               _num_workers;
3477 
3478   // Variables used to claim nmethods.
3479   CompiledMethod* _first_nmethod;
3480   CompiledMethod* volatile _claimed_nmethod;
3481 
3482   // The list of nmethods that need to be processed by the second pass.
3483   CompiledMethod* volatile _postponed_list;
3484   volatile uint            _num_entered_barrier;
3485 
3486  public:
3487   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3488       _is_alive(is_alive),
3489       _unloading_occurred(unloading_occurred),
3490       _num_workers(num_workers),
3491       _first_nmethod(NULL),
3492       _claimed_nmethod(NULL),
3493       _postponed_list(NULL),
3494       _num_entered_barrier(0)
3495   {
3496     CompiledMethod::increase_unloading_clock();
3497     // Get first alive nmethod
3498     CompiledMethodIterator iter = CompiledMethodIterator();
3499     if(iter.next_alive()) {
3500       _first_nmethod = iter.method();
3501     }
3502     _claimed_nmethod = _first_nmethod;
3503   }
3504 
3505   ~G1CodeCacheUnloadingTask() {
3506     CodeCache::verify_clean_inline_caches();
3507 
3508     CodeCache::set_needs_cache_clean(false);
3509     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3510 
3511     CodeCache::verify_icholder_relocations();
3512   }
3513 
3514  private:
3515   void add_to_postponed_list(CompiledMethod* nm) {
3516       CompiledMethod* old;
3517       do {
3518         old = _postponed_list;
3519         nm->set_unloading_next(old);
3520       } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3521   }
3522 
3523   void clean_nmethod(CompiledMethod* nm) {
3524     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3525 
3526     if (postponed) {
3527       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3528       add_to_postponed_list(nm);
3529     }
3530 
3531     // Mark that this thread has been cleaned/unloaded.
3532     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3533     nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3534   }
3535 
3536   void clean_nmethod_postponed(CompiledMethod* nm) {
3537     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3538   }
3539 
3540   static const int MaxClaimNmethods = 16;
3541 
3542   void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3543     CompiledMethod* first;
3544     CompiledMethodIterator last;
3545 
3546     do {
3547       *num_claimed_nmethods = 0;
3548 
3549       first = _claimed_nmethod;
3550       last = CompiledMethodIterator(first);
3551 
3552       if (first != NULL) {
3553 
3554         for (int i = 0; i < MaxClaimNmethods; i++) {
3555           if (!last.next_alive()) {
3556             break;
3557           }
3558           claimed_nmethods[i] = last.method();
3559           (*num_claimed_nmethods)++;
3560         }
3561       }
3562 
3563     } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3564   }
3565 
3566   CompiledMethod* claim_postponed_nmethod() {
3567     CompiledMethod* claim;
3568     CompiledMethod* next;
3569 
3570     do {
3571       claim = _postponed_list;
3572       if (claim == NULL) {
3573         return NULL;
3574       }
3575 
3576       next = claim->unloading_next();
3577 
3578     } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3579 
3580     return claim;
3581   }
3582 
3583  public:
3584   // Mark that we're done with the first pass of nmethod cleaning.
3585   void barrier_mark(uint worker_id) {
3586     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3587     _num_entered_barrier++;
3588     if (_num_entered_barrier == _num_workers) {
3589       ml.notify_all();
3590     }
3591   }
3592 
3593   // See if we have to wait for the other workers to
3594   // finish their first-pass nmethod cleaning work.
3595   void barrier_wait(uint worker_id) {
3596     if (_num_entered_barrier < _num_workers) {
3597       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3598       while (_num_entered_barrier < _num_workers) {
3599           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3600       }
3601     }
3602   }
3603 
3604   // Cleaning and unloading of nmethods. Some work has to be postponed
3605   // to the second pass, when we know which nmethods survive.
3606   void work_first_pass(uint worker_id) {
3607     // The first nmethods is claimed by the first worker.
3608     if (worker_id == 0 && _first_nmethod != NULL) {
3609       clean_nmethod(_first_nmethod);
3610       _first_nmethod = NULL;
3611     }
3612 
3613     int num_claimed_nmethods;
3614     CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3615 
3616     while (true) {
3617       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3618 
3619       if (num_claimed_nmethods == 0) {
3620         break;
3621       }
3622 
3623       for (int i = 0; i < num_claimed_nmethods; i++) {
3624         clean_nmethod(claimed_nmethods[i]);
3625       }
3626     }
3627   }
3628 
3629   void work_second_pass(uint worker_id) {
3630     CompiledMethod* nm;
3631     // Take care of postponed nmethods.
3632     while ((nm = claim_postponed_nmethod()) != NULL) {
3633       clean_nmethod_postponed(nm);
3634     }
3635   }
3636 };
3637 
3638 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3639 
3640 class G1KlassCleaningTask : public StackObj {
3641   BoolObjectClosure*                      _is_alive;
3642   volatile int                            _clean_klass_tree_claimed;
3643   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3644 
3645  public:
3646   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3647       _is_alive(is_alive),
3648       _clean_klass_tree_claimed(0),
3649       _klass_iterator() {
3650   }
3651 
3652  private:
3653   bool claim_clean_klass_tree_task() {
3654     if (_clean_klass_tree_claimed) {
3655       return false;
3656     }
3657 
3658     return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3659   }
3660 
3661   InstanceKlass* claim_next_klass() {
3662     Klass* klass;
3663     do {
3664       klass =_klass_iterator.next_klass();
3665     } while (klass != NULL && !klass->is_instance_klass());
3666 
3667     // this can be null so don't call InstanceKlass::cast
3668     return static_cast<InstanceKlass*>(klass);
3669   }
3670 
3671 public:
3672 
3673   void clean_klass(InstanceKlass* ik) {
3674     ik->clean_weak_instanceklass_links(_is_alive);
3675   }
3676 
3677   void work() {
3678     ResourceMark rm;
3679 
3680     // One worker will clean the subklass/sibling klass tree.
3681     if (claim_clean_klass_tree_task()) {
3682       Klass::clean_subklass_tree(_is_alive);
3683     }
3684 
3685     // All workers will help cleaning the classes,
3686     InstanceKlass* klass;
3687     while ((klass = claim_next_klass()) != NULL) {
3688       clean_klass(klass);
3689     }
3690   }
3691 };
3692 
3693 class G1ResolvedMethodCleaningTask : public StackObj {
3694   BoolObjectClosure* _is_alive;
3695   volatile int       _resolved_method_task_claimed;
3696 public:
3697   G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3698       _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3699 
3700   bool claim_resolved_method_task() {
3701     if (_resolved_method_task_claimed) {
3702       return false;
3703     }
3704     return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3705   }
3706 
3707   // These aren't big, one thread can do it all.
3708   void work() {
3709     if (claim_resolved_method_task()) {
3710       ResolvedMethodTable::unlink(_is_alive);
3711     }
3712   }
3713 };
3714 
3715 
3716 // To minimize the remark pause times, the tasks below are done in parallel.
3717 class G1ParallelCleaningTask : public AbstractGangTask {
3718 private:
3719   G1StringAndSymbolCleaningTask _string_symbol_task;
3720   G1CodeCacheUnloadingTask      _code_cache_task;
3721   G1KlassCleaningTask           _klass_cleaning_task;
3722   G1ResolvedMethodCleaningTask  _resolved_method_cleaning_task;
3723 
3724 public:
3725   // The constructor is run in the VMThread.
3726   G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3727       AbstractGangTask("Parallel Cleaning"),
3728       _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3729       _code_cache_task(num_workers, is_alive, unloading_occurred),
3730       _klass_cleaning_task(is_alive),
3731       _resolved_method_cleaning_task(is_alive) {
3732   }
3733 
3734   // The parallel work done by all worker threads.
3735   void work(uint worker_id) {
3736     // Do first pass of code cache cleaning.
3737     _code_cache_task.work_first_pass(worker_id);
3738 
3739     // Let the threads mark that the first pass is done.
3740     _code_cache_task.barrier_mark(worker_id);
3741 
3742     // Clean the Strings and Symbols.
3743     _string_symbol_task.work(worker_id);
3744 
3745     // Clean unreferenced things in the ResolvedMethodTable
3746     _resolved_method_cleaning_task.work();
3747 
3748     // Wait for all workers to finish the first code cache cleaning pass.
3749     _code_cache_task.barrier_wait(worker_id);
3750 
3751     // Do the second code cache cleaning work, which realize on
3752     // the liveness information gathered during the first pass.
3753     _code_cache_task.work_second_pass(worker_id);
3754 
3755     // Clean all klasses that were not unloaded.
3756     _klass_cleaning_task.work();
3757   }
3758 };
3759 
3760 
3761 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3762                                         bool class_unloading_occurred) {
3763   uint n_workers = workers()->active_workers();
3764 
3765   G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3766   workers()->run_task(&g1_unlink_task);
3767 }
3768 
3769 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3770                                        bool process_strings,
3771                                        bool process_symbols,
3772                                        bool process_string_dedup) {
3773   if (!process_strings && !process_symbols && !process_string_dedup) {
3774     // Nothing to clean.
3775     return;
3776   }
3777 
3778   G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3779   workers()->run_task(&g1_unlink_task);
3780 
3781 }
3782 
3783 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3784  private:
3785   DirtyCardQueueSet* _queue;
3786   G1CollectedHeap* _g1h;
3787  public:
3788   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3789     _queue(queue), _g1h(g1h) { }
3790 
3791   virtual void work(uint worker_id) {
3792     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3793     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3794 
3795     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3796     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3797 
3798     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3799   }
3800 };
3801 
3802 void G1CollectedHeap::redirty_logged_cards() {
3803   double redirty_logged_cards_start = os::elapsedTime();
3804 
3805   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3806   dirty_card_queue_set().reset_for_par_iteration();
3807   workers()->run_task(&redirty_task);
3808 
3809   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3810   dcq.merge_bufferlists(&dirty_card_queue_set());
3811   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3812 
3813   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3814 }
3815 
3816 // Weak Reference Processing support
3817 
3818 // An always "is_alive" closure that is used to preserve referents.
3819 // If the object is non-null then it's alive.  Used in the preservation
3820 // of referent objects that are pointed to by reference objects
3821 // discovered by the CM ref processor.
3822 class G1AlwaysAliveClosure: public BoolObjectClosure {
3823   G1CollectedHeap* _g1;
3824 public:
3825   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3826   bool do_object_b(oop p) {
3827     if (p != NULL) {
3828       return true;
3829     }
3830     return false;
3831   }
3832 };
3833 
3834 bool G1STWIsAliveClosure::do_object_b(oop p) {
3835   // An object is reachable if it is outside the collection set,
3836   // or is inside and copied.
3837   return !_g1->is_in_cset(p) || p->is_forwarded();
3838 }
3839 
3840 // Non Copying Keep Alive closure
3841 class G1KeepAliveClosure: public OopClosure {
3842   G1CollectedHeap* _g1;
3843 public:
3844   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3845   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3846   void do_oop(oop* p) {
3847     oop obj = *p;
3848     assert(obj != NULL, "the caller should have filtered out NULL values");
3849 
3850     const InCSetState cset_state = _g1->in_cset_state(obj);
3851     if (!cset_state.is_in_cset_or_humongous()) {
3852       return;
3853     }
3854     if (cset_state.is_in_cset()) {
3855       assert( obj->is_forwarded(), "invariant" );
3856       *p = obj->forwardee();
3857     } else {
3858       assert(!obj->is_forwarded(), "invariant" );
3859       assert(cset_state.is_humongous(),
3860              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3861       _g1->set_humongous_is_live(obj);
3862     }
3863   }
3864 };
3865 
3866 // Copying Keep Alive closure - can be called from both
3867 // serial and parallel code as long as different worker
3868 // threads utilize different G1ParScanThreadState instances
3869 // and different queues.
3870 
3871 class G1CopyingKeepAliveClosure: public OopClosure {
3872   G1CollectedHeap*         _g1h;
3873   OopClosure*              _copy_non_heap_obj_cl;
3874   G1ParScanThreadState*    _par_scan_state;
3875 
3876 public:
3877   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3878                             OopClosure* non_heap_obj_cl,
3879                             G1ParScanThreadState* pss):
3880     _g1h(g1h),
3881     _copy_non_heap_obj_cl(non_heap_obj_cl),
3882     _par_scan_state(pss)
3883   {}
3884 
3885   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3886   virtual void do_oop(      oop* p) { do_oop_work(p); }
3887 
3888   template <class T> void do_oop_work(T* p) {
3889     oop obj = oopDesc::load_decode_heap_oop(p);
3890 
3891     if (_g1h->is_in_cset_or_humongous(obj)) {
3892       // If the referent object has been forwarded (either copied
3893       // to a new location or to itself in the event of an
3894       // evacuation failure) then we need to update the reference
3895       // field and, if both reference and referent are in the G1
3896       // heap, update the RSet for the referent.
3897       //
3898       // If the referent has not been forwarded then we have to keep
3899       // it alive by policy. Therefore we have copy the referent.
3900       //
3901       // If the reference field is in the G1 heap then we can push
3902       // on the PSS queue. When the queue is drained (after each
3903       // phase of reference processing) the object and it's followers
3904       // will be copied, the reference field set to point to the
3905       // new location, and the RSet updated. Otherwise we need to
3906       // use the the non-heap or metadata closures directly to copy
3907       // the referent object and update the pointer, while avoiding
3908       // updating the RSet.
3909 
3910       if (_g1h->is_in_g1_reserved(p)) {
3911         _par_scan_state->push_on_queue(p);
3912       } else {
3913         assert(!Metaspace::contains((const void*)p),
3914                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3915         _copy_non_heap_obj_cl->do_oop(p);
3916       }
3917     }
3918   }
3919 };
3920 
3921 // Serial drain queue closure. Called as the 'complete_gc'
3922 // closure for each discovered list in some of the
3923 // reference processing phases.
3924 
3925 class G1STWDrainQueueClosure: public VoidClosure {
3926 protected:
3927   G1CollectedHeap* _g1h;
3928   G1ParScanThreadState* _par_scan_state;
3929 
3930   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3931 
3932 public:
3933   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3934     _g1h(g1h),
3935     _par_scan_state(pss)
3936   { }
3937 
3938   void do_void() {
3939     G1ParScanThreadState* const pss = par_scan_state();
3940     pss->trim_queue();
3941   }
3942 };
3943 
3944 // Parallel Reference Processing closures
3945 
3946 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3947 // processing during G1 evacuation pauses.
3948 
3949 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3950 private:
3951   G1CollectedHeap*          _g1h;
3952   G1ParScanThreadStateSet*  _pss;
3953   RefToScanQueueSet*        _queues;
3954   WorkGang*                 _workers;
3955   uint                      _active_workers;
3956 
3957 public:
3958   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3959                            G1ParScanThreadStateSet* per_thread_states,
3960                            WorkGang* workers,
3961                            RefToScanQueueSet *task_queues,
3962                            uint n_workers) :
3963     _g1h(g1h),
3964     _pss(per_thread_states),
3965     _queues(task_queues),
3966     _workers(workers),
3967     _active_workers(n_workers)
3968   {
3969     g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3970   }
3971 
3972   // Executes the given task using concurrent marking worker threads.
3973   virtual void execute(ProcessTask& task);
3974   virtual void execute(EnqueueTask& task);
3975 };
3976 
3977 // Gang task for possibly parallel reference processing
3978 
3979 class G1STWRefProcTaskProxy: public AbstractGangTask {
3980   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3981   ProcessTask&     _proc_task;
3982   G1CollectedHeap* _g1h;
3983   G1ParScanThreadStateSet* _pss;
3984   RefToScanQueueSet* _task_queues;
3985   ParallelTaskTerminator* _terminator;
3986 
3987 public:
3988   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3989                         G1CollectedHeap* g1h,
3990                         G1ParScanThreadStateSet* per_thread_states,
3991                         RefToScanQueueSet *task_queues,
3992                         ParallelTaskTerminator* terminator) :
3993     AbstractGangTask("Process reference objects in parallel"),
3994     _proc_task(proc_task),
3995     _g1h(g1h),
3996     _pss(per_thread_states),
3997     _task_queues(task_queues),
3998     _terminator(terminator)
3999   {}
4000 
4001   virtual void work(uint worker_id) {
4002     // The reference processing task executed by a single worker.
4003     ResourceMark rm;
4004     HandleMark   hm;
4005 
4006     G1STWIsAliveClosure is_alive(_g1h);
4007 
4008     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4009     pss->set_ref_processor(NULL);
4010 
4011     // Keep alive closure.
4012     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4013 
4014     // Complete GC closure
4015     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4016 
4017     // Call the reference processing task's work routine.
4018     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4019 
4020     // Note we cannot assert that the refs array is empty here as not all
4021     // of the processing tasks (specifically phase2 - pp2_work) execute
4022     // the complete_gc closure (which ordinarily would drain the queue) so
4023     // the queue may not be empty.
4024   }
4025 };
4026 
4027 // Driver routine for parallel reference processing.
4028 // Creates an instance of the ref processing gang
4029 // task and has the worker threads execute it.
4030 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4031   assert(_workers != NULL, "Need parallel worker threads.");
4032 
4033   ParallelTaskTerminator terminator(_active_workers, _queues);
4034   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4035 
4036   _workers->run_task(&proc_task_proxy);
4037 }
4038 
4039 // Gang task for parallel reference enqueueing.
4040 
4041 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4042   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4043   EnqueueTask& _enq_task;
4044 
4045 public:
4046   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4047     AbstractGangTask("Enqueue reference objects in parallel"),
4048     _enq_task(enq_task)
4049   { }
4050 
4051   virtual void work(uint worker_id) {
4052     _enq_task.work(worker_id);
4053   }
4054 };
4055 
4056 // Driver routine for parallel reference enqueueing.
4057 // Creates an instance of the ref enqueueing gang
4058 // task and has the worker threads execute it.
4059 
4060 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4061   assert(_workers != NULL, "Need parallel worker threads.");
4062 
4063   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4064 
4065   _workers->run_task(&enq_task_proxy);
4066 }
4067 
4068 // End of weak reference support closures
4069 
4070 // Abstract task used to preserve (i.e. copy) any referent objects
4071 // that are in the collection set and are pointed to by reference
4072 // objects discovered by the CM ref processor.
4073 
4074 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4075 protected:
4076   G1CollectedHeap*         _g1h;
4077   G1ParScanThreadStateSet* _pss;
4078   RefToScanQueueSet*       _queues;
4079   ParallelTaskTerminator   _terminator;
4080   uint                     _n_workers;
4081 
4082 public:
4083   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4084     AbstractGangTask("ParPreserveCMReferents"),
4085     _g1h(g1h),
4086     _pss(per_thread_states),
4087     _queues(task_queues),
4088     _terminator(workers, _queues),
4089     _n_workers(workers)
4090   {
4091     g1h->ref_processor_cm()->set_active_mt_degree(workers);
4092   }
4093 
4094   void work(uint worker_id) {
4095     G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4096 
4097     ResourceMark rm;
4098     HandleMark   hm;
4099 
4100     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4101     pss->set_ref_processor(NULL);
4102     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4103 
4104     // Is alive closure
4105     G1AlwaysAliveClosure always_alive(_g1h);
4106 
4107     // Copying keep alive closure. Applied to referent objects that need
4108     // to be copied.
4109     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4110 
4111     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4112 
4113     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4114     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4115 
4116     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4117     // So this must be true - but assert just in case someone decides to
4118     // change the worker ids.
4119     assert(worker_id < limit, "sanity");
4120     assert(!rp->discovery_is_atomic(), "check this code");
4121 
4122     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4123     for (uint idx = worker_id; idx < limit; idx += stride) {
4124       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4125 
4126       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4127       while (iter.has_next()) {
4128         // Since discovery is not atomic for the CM ref processor, we
4129         // can see some null referent objects.
4130         iter.load_ptrs(DEBUG_ONLY(true));
4131         oop ref = iter.obj();
4132 
4133         // This will filter nulls.
4134         if (iter.is_referent_alive()) {
4135           iter.make_referent_alive();
4136         }
4137         iter.move_to_next();
4138       }
4139     }
4140 
4141     // Drain the queue - which may cause stealing
4142     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4143     drain_queue.do_void();
4144     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4145     assert(pss->queue_is_empty(), "should be");
4146   }
4147 };
4148 
4149 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4150   // Any reference objects, in the collection set, that were 'discovered'
4151   // by the CM ref processor should have already been copied (either by
4152   // applying the external root copy closure to the discovered lists, or
4153   // by following an RSet entry).
4154   //
4155   // But some of the referents, that are in the collection set, that these
4156   // reference objects point to may not have been copied: the STW ref
4157   // processor would have seen that the reference object had already
4158   // been 'discovered' and would have skipped discovering the reference,
4159   // but would not have treated the reference object as a regular oop.
4160   // As a result the copy closure would not have been applied to the
4161   // referent object.
4162   //
4163   // We need to explicitly copy these referent objects - the references
4164   // will be processed at the end of remarking.
4165   //
4166   // We also need to do this copying before we process the reference
4167   // objects discovered by the STW ref processor in case one of these
4168   // referents points to another object which is also referenced by an
4169   // object discovered by the STW ref processor.
4170   double preserve_cm_referents_time = 0.0;
4171 
4172   // To avoid spawning task when there is no work to do, check that
4173   // a concurrent cycle is active and that some references have been
4174   // discovered.
4175   if (concurrent_mark()->cm_thread()->during_cycle() &&
4176       ref_processor_cm()->has_discovered_references()) {
4177     double preserve_cm_referents_start = os::elapsedTime();
4178     uint no_of_gc_workers = workers()->active_workers();
4179     G1ParPreserveCMReferentsTask keep_cm_referents(this,
4180                                                    per_thread_states,
4181                                                    no_of_gc_workers,
4182                                                    _task_queues);
4183     workers()->run_task(&keep_cm_referents);
4184     preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4185   }
4186 
4187   g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4188 }
4189 
4190 // Weak Reference processing during an evacuation pause (part 1).
4191 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4192   double ref_proc_start = os::elapsedTime();
4193 
4194   ReferenceProcessor* rp = _ref_processor_stw;
4195   assert(rp->discovery_enabled(), "should have been enabled");
4196 
4197   // Closure to test whether a referent is alive.
4198   G1STWIsAliveClosure is_alive(this);
4199 
4200   // Even when parallel reference processing is enabled, the processing
4201   // of JNI refs is serial and performed serially by the current thread
4202   // rather than by a worker. The following PSS will be used for processing
4203   // JNI refs.
4204 
4205   // Use only a single queue for this PSS.
4206   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4207   pss->set_ref_processor(NULL);
4208   assert(pss->queue_is_empty(), "pre-condition");
4209 
4210   // Keep alive closure.
4211   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4212 
4213   // Serial Complete GC closure
4214   G1STWDrainQueueClosure drain_queue(this, pss);
4215 
4216   // Setup the soft refs policy...
4217   rp->setup_policy(false);
4218 
4219   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4220 
4221   ReferenceProcessorStats stats;
4222   if (!rp->processing_is_mt()) {
4223     // Serial reference processing...
4224     stats = rp->process_discovered_references(&is_alive,
4225                                               &keep_alive,
4226                                               &drain_queue,
4227                                               NULL,
4228                                               pt);
4229   } else {
4230     uint no_of_gc_workers = workers()->active_workers();
4231 
4232     // Parallel reference processing
4233     assert(no_of_gc_workers <= rp->max_num_q(),
4234            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4235            no_of_gc_workers,  rp->max_num_q());
4236 
4237     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4238     stats = rp->process_discovered_references(&is_alive,
4239                                               &keep_alive,
4240                                               &drain_queue,
4241                                               &par_task_executor,
4242                                               pt);
4243   }
4244 
4245   _gc_tracer_stw->report_gc_reference_stats(stats);
4246 
4247   // We have completed copying any necessary live referent objects.
4248   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4249 
4250   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4251   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4252 }
4253 
4254 // Weak Reference processing during an evacuation pause (part 2).
4255 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4256   double ref_enq_start = os::elapsedTime();
4257 
4258   ReferenceProcessor* rp = _ref_processor_stw;
4259   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4260 
4261   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4262 
4263   // Now enqueue any remaining on the discovered lists on to
4264   // the pending list.
4265   if (!rp->processing_is_mt()) {
4266     // Serial reference processing...
4267     rp->enqueue_discovered_references(NULL, pt);
4268   } else {
4269     // Parallel reference enqueueing
4270 
4271     uint n_workers = workers()->active_workers();
4272 
4273     assert(n_workers <= rp->max_num_q(),
4274            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4275            n_workers,  rp->max_num_q());
4276 
4277     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4278     rp->enqueue_discovered_references(&par_task_executor, pt);
4279   }
4280 
4281   rp->verify_no_references_recorded();
4282   assert(!rp->discovery_enabled(), "should have been disabled");
4283 
4284   // If during an initial mark pause we install a pending list head which is not otherwise reachable
4285   // ensure that it is marked in the bitmap for concurrent marking to discover.
4286   if (collector_state()->during_initial_mark_pause()) {
4287     oop pll_head = Universe::reference_pending_list();
4288     if (pll_head != NULL) {
4289       _cm->mark_in_next_bitmap(pll_head);
4290     }
4291   }
4292 
4293   // FIXME
4294   // CM's reference processing also cleans up the string and symbol tables.
4295   // Should we do that here also? We could, but it is a serial operation
4296   // and could significantly increase the pause time.
4297 
4298   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4299   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4300 }
4301 
4302 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4303   double merge_pss_time_start = os::elapsedTime();
4304   per_thread_states->flush();
4305   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4306 }
4307 
4308 void G1CollectedHeap::pre_evacuate_collection_set() {
4309   _expand_heap_after_alloc_failure = true;
4310   _evacuation_failed = false;
4311 
4312   // Disable the hot card cache.
4313   _hot_card_cache->reset_hot_cache_claimed_index();
4314   _hot_card_cache->set_use_cache(false);
4315 
4316   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4317   _preserved_marks_set.assert_empty();
4318 
4319   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4320 
4321   // InitialMark needs claim bits to keep track of the marked-through CLDs.
4322   if (collector_state()->during_initial_mark_pause()) {
4323     double start_clear_claimed_marks = os::elapsedTime();
4324 
4325     ClassLoaderDataGraph::clear_claimed_marks();
4326 
4327     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4328     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4329   }
4330 }
4331 
4332 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4333   // Should G1EvacuationFailureALot be in effect for this GC?
4334   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4335 
4336   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4337 
4338   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4339 
4340   double start_par_time_sec = os::elapsedTime();
4341   double end_par_time_sec;
4342 
4343   {
4344     const uint n_workers = workers()->active_workers();
4345     G1RootProcessor root_processor(this, n_workers);
4346     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4347 
4348     print_termination_stats_hdr();
4349 
4350     workers()->run_task(&g1_par_task);
4351     end_par_time_sec = os::elapsedTime();
4352 
4353     // Closing the inner scope will execute the destructor
4354     // for the G1RootProcessor object. We record the current
4355     // elapsed time before closing the scope so that time
4356     // taken for the destructor is NOT included in the
4357     // reported parallel time.
4358   }
4359 
4360   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4361   phase_times->record_par_time(par_time_ms);
4362 
4363   double code_root_fixup_time_ms =
4364         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4365   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4366 }
4367 
4368 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4369   // Process any discovered reference objects - we have
4370   // to do this _before_ we retire the GC alloc regions
4371   // as we may have to copy some 'reachable' referent
4372   // objects (and their reachable sub-graphs) that were
4373   // not copied during the pause.
4374   if (g1_policy()->should_process_references()) {
4375     preserve_cm_referents(per_thread_states);
4376     process_discovered_references(per_thread_states);
4377   } else {
4378     ref_processor_stw()->verify_no_references_recorded();
4379   }
4380 
4381   G1STWIsAliveClosure is_alive(this);
4382   G1KeepAliveClosure keep_alive(this);
4383 
4384   {
4385     double start = os::elapsedTime();
4386 
4387     WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4388 
4389     double time_ms = (os::elapsedTime() - start) * 1000.0;
4390     g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4391   }
4392 
4393   if (G1StringDedup::is_enabled()) {
4394     double fixup_start = os::elapsedTime();
4395 
4396     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4397 
4398     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4399     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4400   }
4401 
4402   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4403 
4404   if (evacuation_failed()) {
4405     restore_after_evac_failure();
4406 
4407     // Reset the G1EvacuationFailureALot counters and flags
4408     // Note: the values are reset only when an actual
4409     // evacuation failure occurs.
4410     NOT_PRODUCT(reset_evacuation_should_fail();)
4411   }
4412 
4413   _preserved_marks_set.assert_empty();
4414 
4415   // Enqueue any remaining references remaining on the STW
4416   // reference processor's discovered lists. We need to do
4417   // this after the card table is cleaned (and verified) as
4418   // the act of enqueueing entries on to the pending list
4419   // will log these updates (and dirty their associated
4420   // cards). We need these updates logged to update any
4421   // RSets.
4422   if (g1_policy()->should_process_references()) {
4423     enqueue_discovered_references(per_thread_states);
4424   } else {
4425     g1_policy()->phase_times()->record_ref_enq_time(0);
4426   }
4427 
4428   _allocator->release_gc_alloc_regions(evacuation_info);
4429 
4430   merge_per_thread_state_info(per_thread_states);
4431 
4432   // Reset and re-enable the hot card cache.
4433   // Note the counts for the cards in the regions in the
4434   // collection set are reset when the collection set is freed.
4435   _hot_card_cache->reset_hot_cache();
4436   _hot_card_cache->set_use_cache(true);
4437 
4438   purge_code_root_memory();
4439 
4440   redirty_logged_cards();
4441 #if COMPILER2_OR_JVMCI
4442   double start = os::elapsedTime();
4443   DerivedPointerTable::update_pointers();
4444   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4445 #endif
4446   g1_policy()->print_age_table();
4447 }
4448 
4449 void G1CollectedHeap::record_obj_copy_mem_stats() {
4450   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4451 
4452   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4453                                                create_g1_evac_summary(&_old_evac_stats));
4454 }
4455 
4456 void G1CollectedHeap::free_region(HeapRegion* hr,
4457                                   FreeRegionList* free_list,
4458                                   bool skip_remset,
4459                                   bool skip_hot_card_cache,
4460                                   bool locked) {
4461   assert(!hr->is_free(), "the region should not be free");
4462   assert(!hr->is_empty(), "the region should not be empty");
4463   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4464   assert(free_list != NULL, "pre-condition");
4465 
4466   if (G1VerifyBitmaps) {
4467     MemRegion mr(hr->bottom(), hr->end());
4468     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4469   }
4470 
4471   // Clear the card counts for this region.
4472   // Note: we only need to do this if the region is not young
4473   // (since we don't refine cards in young regions).
4474   if (!skip_hot_card_cache && !hr->is_young()) {
4475     _hot_card_cache->reset_card_counts(hr);
4476   }
4477   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4478   free_list->add_ordered(hr);
4479 }
4480 
4481 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4482                                             FreeRegionList* free_list,
4483                                             bool skip_remset) {
4484   assert(hr->is_humongous(), "this is only for humongous regions");
4485   assert(free_list != NULL, "pre-condition");
4486   hr->clear_humongous();
4487   free_region(hr, free_list, skip_remset);
4488 }
4489 
4490 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4491                                            const uint humongous_regions_removed) {
4492   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4493     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4494     _old_set.bulk_remove(old_regions_removed);
4495     _humongous_set.bulk_remove(humongous_regions_removed);
4496   }
4497 
4498 }
4499 
4500 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4501   assert(list != NULL, "list can't be null");
4502   if (!list->is_empty()) {
4503     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4504     _hrm.insert_list_into_free_list(list);
4505   }
4506 }
4507 
4508 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4509   decrease_used(bytes);
4510 }
4511 
4512 class G1ParScrubRemSetTask: public AbstractGangTask {
4513 protected:
4514   G1RemSet* _g1rs;
4515   HeapRegionClaimer _hrclaimer;
4516 
4517 public:
4518   G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4519     AbstractGangTask("G1 ScrubRS"),
4520     _g1rs(g1_rs),
4521     _hrclaimer(num_workers) {
4522   }
4523 
4524   void work(uint worker_id) {
4525     _g1rs->scrub(worker_id, &_hrclaimer);
4526   }
4527 };
4528 
4529 void G1CollectedHeap::scrub_rem_set() {
4530   uint num_workers = workers()->active_workers();
4531   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4532   workers()->run_task(&g1_par_scrub_rs_task);
4533 }
4534 
4535 class G1FreeCollectionSetTask : public AbstractGangTask {
4536 private:
4537 
4538   // Closure applied to all regions in the collection set to do work that needs to
4539   // be done serially in a single thread.
4540   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4541   private:
4542     EvacuationInfo* _evacuation_info;
4543     const size_t* _surviving_young_words;
4544 
4545     // Bytes used in successfully evacuated regions before the evacuation.
4546     size_t _before_used_bytes;
4547     // Bytes used in unsucessfully evacuated regions before the evacuation
4548     size_t _after_used_bytes;
4549 
4550     size_t _bytes_allocated_in_old_since_last_gc;
4551 
4552     size_t _failure_used_words;
4553     size_t _failure_waste_words;
4554 
4555     FreeRegionList _local_free_list;
4556   public:
4557     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4558       HeapRegionClosure(),
4559       _evacuation_info(evacuation_info),
4560       _surviving_young_words(surviving_young_words),
4561       _before_used_bytes(0),
4562       _after_used_bytes(0),
4563       _bytes_allocated_in_old_since_last_gc(0),
4564       _failure_used_words(0),
4565       _failure_waste_words(0),
4566       _local_free_list("Local Region List for CSet Freeing") {
4567     }
4568 
4569     virtual bool doHeapRegion(HeapRegion* r) {
4570       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4571 
4572       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4573       g1h->clear_in_cset(r);
4574 
4575       if (r->is_young()) {
4576         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4577                "Young index %d is wrong for region %u of type %s with %u young regions",
4578                r->young_index_in_cset(),
4579                r->hrm_index(),
4580                r->get_type_str(),
4581                g1h->collection_set()->young_region_length());
4582         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4583         r->record_surv_words_in_group(words_survived);
4584       }
4585 
4586       if (!r->evacuation_failed()) {
4587         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4588         _before_used_bytes += r->used();
4589         g1h->free_region(r,
4590                          &_local_free_list,
4591                          true, /* skip_remset */
4592                          true, /* skip_hot_card_cache */
4593                          true  /* locked */);
4594       } else {
4595         r->uninstall_surv_rate_group();
4596         r->set_young_index_in_cset(-1);
4597         r->set_evacuation_failed(false);
4598         // When moving a young gen region to old gen, we "allocate" that whole region
4599         // there. This is in addition to any already evacuated objects. Notify the
4600         // policy about that.
4601         // Old gen regions do not cause an additional allocation: both the objects
4602         // still in the region and the ones already moved are accounted for elsewhere.
4603         if (r->is_young()) {
4604           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4605         }
4606         // The region is now considered to be old.
4607         r->set_old();
4608         // Do some allocation statistics accounting. Regions that failed evacuation
4609         // are always made old, so there is no need to update anything in the young
4610         // gen statistics, but we need to update old gen statistics.
4611         size_t used_words = r->marked_bytes() / HeapWordSize;
4612 
4613         _failure_used_words += used_words;
4614         _failure_waste_words += HeapRegion::GrainWords - used_words;
4615 
4616         g1h->old_set_add(r);
4617         _after_used_bytes += r->used();
4618       }
4619       return false;
4620     }
4621 
4622     void complete_work() {
4623       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4624 
4625       _evacuation_info->set_regions_freed(_local_free_list.length());
4626       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4627 
4628       g1h->prepend_to_freelist(&_local_free_list);
4629       g1h->decrement_summary_bytes(_before_used_bytes);
4630 
4631       G1Policy* policy = g1h->g1_policy();
4632       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4633 
4634       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4635     }
4636   };
4637 
4638   G1CollectionSet* _collection_set;
4639   G1SerialFreeCollectionSetClosure _cl;
4640   const size_t* _surviving_young_words;
4641 
4642   size_t _rs_lengths;
4643 
4644   volatile jint _serial_work_claim;
4645 
4646   struct WorkItem {
4647     uint region_idx;
4648     bool is_young;
4649     bool evacuation_failed;
4650 
4651     WorkItem(HeapRegion* r) {
4652       region_idx = r->hrm_index();
4653       is_young = r->is_young();
4654       evacuation_failed = r->evacuation_failed();
4655     }
4656   };
4657 
4658   volatile size_t _parallel_work_claim;
4659   size_t _num_work_items;
4660   WorkItem* _work_items;
4661 
4662   void do_serial_work() {
4663     // Need to grab the lock to be allowed to modify the old region list.
4664     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4665     _collection_set->iterate(&_cl);
4666   }
4667 
4668   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4669     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4670 
4671     HeapRegion* r = g1h->region_at(region_idx);
4672     assert(!g1h->is_on_master_free_list(r), "sanity");
4673 
4674     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4675 
4676     if (!is_young) {
4677       g1h->_hot_card_cache->reset_card_counts(r);
4678     }
4679 
4680     if (!evacuation_failed) {
4681       r->rem_set()->clear_locked();
4682     }
4683   }
4684 
4685   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4686   private:
4687     size_t _cur_idx;
4688     WorkItem* _work_items;
4689   public:
4690     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4691 
4692     virtual bool doHeapRegion(HeapRegion* r) {
4693       _work_items[_cur_idx++] = WorkItem(r);
4694       return false;
4695     }
4696   };
4697 
4698   void prepare_work() {
4699     G1PrepareFreeCollectionSetClosure cl(_work_items);
4700     _collection_set->iterate(&cl);
4701   }
4702 
4703   void complete_work() {
4704     _cl.complete_work();
4705 
4706     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4707     policy->record_max_rs_lengths(_rs_lengths);
4708     policy->cset_regions_freed();
4709   }
4710 public:
4711   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4712     AbstractGangTask("G1 Free Collection Set"),
4713     _cl(evacuation_info, surviving_young_words),
4714     _collection_set(collection_set),
4715     _surviving_young_words(surviving_young_words),
4716     _serial_work_claim(0),
4717     _rs_lengths(0),
4718     _parallel_work_claim(0),
4719     _num_work_items(collection_set->region_length()),
4720     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4721     prepare_work();
4722   }
4723 
4724   ~G1FreeCollectionSetTask() {
4725     complete_work();
4726     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4727   }
4728 
4729   // Chunk size for work distribution. The chosen value has been determined experimentally
4730   // to be a good tradeoff between overhead and achievable parallelism.
4731   static uint chunk_size() { return 32; }
4732 
4733   virtual void work(uint worker_id) {
4734     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4735 
4736     // Claim serial work.
4737     if (_serial_work_claim == 0) {
4738       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4739       if (value == 0) {
4740         double serial_time = os::elapsedTime();
4741         do_serial_work();
4742         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4743       }
4744     }
4745 
4746     // Start parallel work.
4747     double young_time = 0.0;
4748     bool has_young_time = false;
4749     double non_young_time = 0.0;
4750     bool has_non_young_time = false;
4751 
4752     while (true) {
4753       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4754       size_t cur = end - chunk_size();
4755 
4756       if (cur >= _num_work_items) {
4757         break;
4758       }
4759 
4760       double start_time = os::elapsedTime();
4761 
4762       end = MIN2(end, _num_work_items);
4763 
4764       for (; cur < end; cur++) {
4765         bool is_young = _work_items[cur].is_young;
4766 
4767         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4768 
4769         double end_time = os::elapsedTime();
4770         double time_taken = end_time - start_time;
4771         if (is_young) {
4772           young_time += time_taken;
4773           has_young_time = true;
4774         } else {
4775           non_young_time += time_taken;
4776           has_non_young_time = true;
4777         }
4778         start_time = end_time;
4779       }
4780     }
4781 
4782     if (has_young_time) {
4783       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4784     }
4785     if (has_non_young_time) {
4786       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4787     }
4788   }
4789 };
4790 
4791 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4792   _eden.clear();
4793 
4794   double free_cset_start_time = os::elapsedTime();
4795 
4796   {
4797     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4798     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4799 
4800     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4801 
4802     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4803                         cl.name(),
4804                         num_workers,
4805                         _collection_set.region_length());
4806     workers()->run_task(&cl, num_workers);
4807   }
4808   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4809 
4810   collection_set->clear();
4811 }
4812 
4813 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4814  private:
4815   FreeRegionList* _free_region_list;
4816   HeapRegionSet* _proxy_set;
4817   uint _humongous_objects_reclaimed;
4818   uint _humongous_regions_reclaimed;
4819   size_t _freed_bytes;
4820  public:
4821 
4822   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4823     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4824   }
4825 
4826   virtual bool doHeapRegion(HeapRegion* r) {
4827     if (!r->is_starts_humongous()) {
4828       return false;
4829     }
4830 
4831     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4832 
4833     oop obj = (oop)r->bottom();
4834     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4835 
4836     // The following checks whether the humongous object is live are sufficient.
4837     // The main additional check (in addition to having a reference from the roots
4838     // or the young gen) is whether the humongous object has a remembered set entry.
4839     //
4840     // A humongous object cannot be live if there is no remembered set for it
4841     // because:
4842     // - there can be no references from within humongous starts regions referencing
4843     // the object because we never allocate other objects into them.
4844     // (I.e. there are no intra-region references that may be missed by the
4845     // remembered set)
4846     // - as soon there is a remembered set entry to the humongous starts region
4847     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4848     // until the end of a concurrent mark.
4849     //
4850     // It is not required to check whether the object has been found dead by marking
4851     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4852     // all objects allocated during that time are considered live.
4853     // SATB marking is even more conservative than the remembered set.
4854     // So if at this point in the collection there is no remembered set entry,
4855     // nobody has a reference to it.
4856     // At the start of collection we flush all refinement logs, and remembered sets
4857     // are completely up-to-date wrt to references to the humongous object.
4858     //
4859     // Other implementation considerations:
4860     // - never consider object arrays at this time because they would pose
4861     // considerable effort for cleaning up the the remembered sets. This is
4862     // required because stale remembered sets might reference locations that
4863     // are currently allocated into.
4864     uint region_idx = r->hrm_index();
4865     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4866         !r->rem_set()->is_empty()) {
4867       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",
4868                                region_idx,
4869                                (size_t)obj->size() * HeapWordSize,
4870                                p2i(r->bottom()),
4871                                r->rem_set()->occupied(),
4872                                r->rem_set()->strong_code_roots_list_length(),
4873                                next_bitmap->is_marked(r->bottom()),
4874                                g1h->is_humongous_reclaim_candidate(region_idx),
4875                                obj->is_typeArray()
4876                               );
4877       return false;
4878     }
4879 
4880     guarantee(obj->is_typeArray(),
4881               "Only eagerly reclaiming type arrays is supported, but the object "
4882               PTR_FORMAT " is not.", p2i(r->bottom()));
4883 
4884     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",
4885                              region_idx,
4886                              (size_t)obj->size() * HeapWordSize,
4887                              p2i(r->bottom()),
4888                              r->rem_set()->occupied(),
4889                              r->rem_set()->strong_code_roots_list_length(),
4890                              next_bitmap->is_marked(r->bottom()),
4891                              g1h->is_humongous_reclaim_candidate(region_idx),
4892                              obj->is_typeArray()
4893                             );
4894 
4895     // Need to clear mark bit of the humongous object if already set.
4896     if (next_bitmap->is_marked(r->bottom())) {
4897       next_bitmap->clear(r->bottom());
4898     }
4899     _humongous_objects_reclaimed++;
4900     do {
4901       HeapRegion* next = g1h->next_region_in_humongous(r);
4902       _freed_bytes += r->used();
4903       r->set_containing_set(NULL);
4904       _humongous_regions_reclaimed++;
4905       g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4906       r = next;
4907     } while (r != NULL);
4908 
4909     return false;
4910   }
4911 
4912   uint humongous_objects_reclaimed() {
4913     return _humongous_objects_reclaimed;
4914   }
4915 
4916   uint humongous_regions_reclaimed() {
4917     return _humongous_regions_reclaimed;
4918   }
4919 
4920   size_t bytes_freed() const {
4921     return _freed_bytes;
4922   }
4923 };
4924 
4925 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4926   assert_at_safepoint(true);
4927 
4928   if (!G1EagerReclaimHumongousObjects ||
4929       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4930     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4931     return;
4932   }
4933 
4934   double start_time = os::elapsedTime();
4935 
4936   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4937 
4938   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4939   heap_region_iterate(&cl);
4940 
4941   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4942 
4943   G1HRPrinter* hrp = hr_printer();
4944   if (hrp->is_active()) {
4945     FreeRegionListIterator iter(&local_cleanup_list);
4946     while (iter.more_available()) {
4947       HeapRegion* hr = iter.get_next();
4948       hrp->cleanup(hr);
4949     }
4950   }
4951 
4952   prepend_to_freelist(&local_cleanup_list);
4953   decrement_summary_bytes(cl.bytes_freed());
4954 
4955   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4956                                                                     cl.humongous_objects_reclaimed());
4957 }
4958 
4959 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4960 public:
4961   virtual bool doHeapRegion(HeapRegion* r) {
4962     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4963     G1CollectedHeap::heap()->clear_in_cset(r);
4964     r->set_young_index_in_cset(-1);
4965     return false;
4966   }
4967 };
4968 
4969 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4970   G1AbandonCollectionSetClosure cl;
4971   collection_set->iterate(&cl);
4972 
4973   collection_set->clear();
4974   collection_set->stop_incremental_building();
4975 }
4976 
4977 void G1CollectedHeap::set_free_regions_coming() {
4978   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4979 
4980   assert(!free_regions_coming(), "pre-condition");
4981   _free_regions_coming = true;
4982 }
4983 
4984 void G1CollectedHeap::reset_free_regions_coming() {
4985   assert(free_regions_coming(), "pre-condition");
4986 
4987   {
4988     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4989     _free_regions_coming = false;
4990     SecondaryFreeList_lock->notify_all();
4991   }
4992 
4993   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4994 }
4995 
4996 void G1CollectedHeap::wait_while_free_regions_coming() {
4997   // Most of the time we won't have to wait, so let's do a quick test
4998   // first before we take the lock.
4999   if (!free_regions_coming()) {
5000     return;
5001   }
5002 
5003   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5004 
5005   {
5006     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5007     while (free_regions_coming()) {
5008       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5009     }
5010   }
5011 
5012   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5013 }
5014 
5015 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5016   return _allocator->is_retained_old_region(hr);
5017 }
5018 
5019 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5020   _eden.add(hr);
5021   _g1_policy->set_region_eden(hr);
5022 }
5023 
5024 #ifdef ASSERT
5025 
5026 class NoYoungRegionsClosure: public HeapRegionClosure {
5027 private:
5028   bool _success;
5029 public:
5030   NoYoungRegionsClosure() : _success(true) { }
5031   bool doHeapRegion(HeapRegion* r) {
5032     if (r->is_young()) {
5033       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5034                             p2i(r->bottom()), p2i(r->end()));
5035       _success = false;
5036     }
5037     return false;
5038   }
5039   bool success() { return _success; }
5040 };
5041 
5042 bool G1CollectedHeap::check_young_list_empty() {
5043   bool ret = (young_regions_count() == 0);
5044 
5045   NoYoungRegionsClosure closure;
5046   heap_region_iterate(&closure);
5047   ret = ret && closure.success();
5048 
5049   return ret;
5050 }
5051 
5052 #endif // ASSERT
5053 
5054 class TearDownRegionSetsClosure : public HeapRegionClosure {
5055 private:
5056   HeapRegionSet *_old_set;
5057 
5058 public:
5059   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5060 
5061   bool doHeapRegion(HeapRegion* r) {
5062     if (r->is_old()) {
5063       _old_set->remove(r);
5064     } else if(r->is_young()) {
5065       r->uninstall_surv_rate_group();
5066     } else {
5067       // We ignore free regions, we'll empty the free list afterwards.
5068       // We ignore humongous regions, we're not tearing down the
5069       // humongous regions set.
5070       assert(r->is_free() || r->is_humongous(),
5071              "it cannot be another type");
5072     }
5073     return false;
5074   }
5075 
5076   ~TearDownRegionSetsClosure() {
5077     assert(_old_set->is_empty(), "post-condition");
5078   }
5079 };
5080 
5081 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5082   assert_at_safepoint(true /* should_be_vm_thread */);
5083 
5084   if (!free_list_only) {
5085     TearDownRegionSetsClosure cl(&_old_set);
5086     heap_region_iterate(&cl);
5087 
5088     // Note that emptying the _young_list is postponed and instead done as
5089     // the first step when rebuilding the regions sets again. The reason for
5090     // this is that during a full GC string deduplication needs to know if
5091     // a collected region was young or old when the full GC was initiated.
5092   }
5093   _hrm.remove_all_free_regions();
5094 }
5095 
5096 void G1CollectedHeap::increase_used(size_t bytes) {
5097   _summary_bytes_used += bytes;
5098 }
5099 
5100 void G1CollectedHeap::decrease_used(size_t bytes) {
5101   assert(_summary_bytes_used >= bytes,
5102          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5103          _summary_bytes_used, bytes);
5104   _summary_bytes_used -= bytes;
5105 }
5106 
5107 void G1CollectedHeap::set_used(size_t bytes) {
5108   _summary_bytes_used = bytes;
5109 }
5110 
5111 class RebuildRegionSetsClosure : public HeapRegionClosure {
5112 private:
5113   bool            _free_list_only;
5114   HeapRegionSet*   _old_set;
5115   HeapRegionManager*   _hrm;
5116   size_t          _total_used;
5117 
5118 public:
5119   RebuildRegionSetsClosure(bool free_list_only,
5120                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5121     _free_list_only(free_list_only),
5122     _old_set(old_set), _hrm(hrm), _total_used(0) {
5123     assert(_hrm->num_free_regions() == 0, "pre-condition");
5124     if (!free_list_only) {
5125       assert(_old_set->is_empty(), "pre-condition");
5126     }
5127   }
5128 
5129   bool doHeapRegion(HeapRegion* r) {
5130     if (r->is_empty()) {
5131       // Add free regions to the free list
5132       r->set_free();
5133       r->set_allocation_context(AllocationContext::system());
5134       _hrm->insert_into_free_list(r);
5135     } else if (!_free_list_only) {
5136 
5137       if (r->is_humongous()) {
5138         // We ignore humongous regions. We left the humongous set unchanged.
5139       } else {
5140         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5141         // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5142         r->move_to_old();
5143         _old_set->add(r);
5144       }
5145       _total_used += r->used();
5146     }
5147 
5148     return false;
5149   }
5150 
5151   size_t total_used() {
5152     return _total_used;
5153   }
5154 };
5155 
5156 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5157   assert_at_safepoint(true /* should_be_vm_thread */);
5158 
5159   if (!free_list_only) {
5160     _eden.clear();
5161     _survivor.clear();
5162   }
5163 
5164   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5165   heap_region_iterate(&cl);
5166 
5167   if (!free_list_only) {
5168     set_used(cl.total_used());
5169     if (_archive_allocator != NULL) {
5170       _archive_allocator->clear_used();
5171     }
5172   }
5173   assert(used_unlocked() == recalculate_used(),
5174          "inconsistent used_unlocked(), "
5175          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5176          used_unlocked(), recalculate_used());
5177 }
5178 
5179 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5180   HeapRegion* hr = heap_region_containing(p);
5181   return hr->is_in(p);
5182 }
5183 
5184 // Methods for the mutator alloc region
5185 
5186 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5187                                                       bool force) {
5188   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5189   bool should_allocate = g1_policy()->should_allocate_mutator_region();
5190   if (force || should_allocate) {
5191     HeapRegion* new_alloc_region = new_region(word_size,
5192                                               false /* is_old */,
5193                                               false /* do_expand */);
5194     if (new_alloc_region != NULL) {
5195       set_region_short_lived_locked(new_alloc_region);
5196       _hr_printer.alloc(new_alloc_region, !should_allocate);
5197       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5198       return new_alloc_region;
5199     }
5200   }
5201   return NULL;
5202 }
5203 
5204 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5205                                                   size_t allocated_bytes) {
5206   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5207   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5208 
5209   collection_set()->add_eden_region(alloc_region);
5210   increase_used(allocated_bytes);
5211   _hr_printer.retire(alloc_region);
5212   // We update the eden sizes here, when the region is retired,
5213   // instead of when it's allocated, since this is the point that its
5214   // used space has been recored in _summary_bytes_used.
5215   g1mm()->update_eden_size();
5216 }
5217 
5218 // Methods for the GC alloc regions
5219 
5220 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5221   if (dest.is_old()) {
5222     return true;
5223   } else {
5224     return survivor_regions_count() < g1_policy()->max_survivor_regions();
5225   }
5226 }
5227 
5228 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5229   assert(FreeList_lock->owned_by_self(), "pre-condition");
5230 
5231   if (!has_more_regions(dest)) {
5232     return NULL;
5233   }
5234 
5235   const bool is_survivor = dest.is_young();
5236 
5237   HeapRegion* new_alloc_region = new_region(word_size,
5238                                             !is_survivor,
5239                                             true /* do_expand */);
5240   if (new_alloc_region != NULL) {
5241     // We really only need to do this for old regions given that we
5242     // should never scan survivors. But it doesn't hurt to do it
5243     // for survivors too.
5244     new_alloc_region->record_timestamp();
5245     if (is_survivor) {
5246       new_alloc_region->set_survivor();
5247       _survivor.add(new_alloc_region);
5248       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5249     } else {
5250       new_alloc_region->set_old();
5251       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5252     }
5253     _hr_printer.alloc(new_alloc_region);
5254     bool during_im = collector_state()->during_initial_mark_pause();
5255     new_alloc_region->note_start_of_copying(during_im);
5256     return new_alloc_region;
5257   }
5258   return NULL;
5259 }
5260 
5261 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5262                                              size_t allocated_bytes,
5263                                              InCSetState dest) {
5264   bool during_im = collector_state()->during_initial_mark_pause();
5265   alloc_region->note_end_of_copying(during_im);
5266   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5267   if (dest.is_old()) {
5268     _old_set.add(alloc_region);
5269   }
5270   _hr_printer.retire(alloc_region);
5271 }
5272 
5273 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5274   bool expanded = false;
5275   uint index = _hrm.find_highest_free(&expanded);
5276 
5277   if (index != G1_NO_HRM_INDEX) {
5278     if (expanded) {
5279       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5280                                 HeapRegion::GrainWords * HeapWordSize);
5281     }
5282     _hrm.allocate_free_regions_starting_at(index, 1);
5283     return region_at(index);
5284   }
5285   return NULL;
5286 }
5287 
5288 // Optimized nmethod scanning
5289 
5290 class RegisterNMethodOopClosure: public OopClosure {
5291   G1CollectedHeap* _g1h;
5292   nmethod* _nm;
5293 
5294   template <class T> void do_oop_work(T* p) {
5295     T heap_oop = oopDesc::load_heap_oop(p);
5296     if (!oopDesc::is_null(heap_oop)) {
5297       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5298       HeapRegion* hr = _g1h->heap_region_containing(obj);
5299       assert(!hr->is_continues_humongous(),
5300              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5301              " starting at " HR_FORMAT,
5302              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5303 
5304       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5305       hr->add_strong_code_root_locked(_nm);
5306     }
5307   }
5308 
5309 public:
5310   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5311     _g1h(g1h), _nm(nm) {}
5312 
5313   void do_oop(oop* p)       { do_oop_work(p); }
5314   void do_oop(narrowOop* p) { do_oop_work(p); }
5315 };
5316 
5317 class UnregisterNMethodOopClosure: public OopClosure {
5318   G1CollectedHeap* _g1h;
5319   nmethod* _nm;
5320 
5321   template <class T> void do_oop_work(T* p) {
5322     T heap_oop = oopDesc::load_heap_oop(p);
5323     if (!oopDesc::is_null(heap_oop)) {
5324       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5325       HeapRegion* hr = _g1h->heap_region_containing(obj);
5326       assert(!hr->is_continues_humongous(),
5327              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5328              " starting at " HR_FORMAT,
5329              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5330 
5331       hr->remove_strong_code_root(_nm);
5332     }
5333   }
5334 
5335 public:
5336   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5337     _g1h(g1h), _nm(nm) {}
5338 
5339   void do_oop(oop* p)       { do_oop_work(p); }
5340   void do_oop(narrowOop* p) { do_oop_work(p); }
5341 };
5342 
5343 // Returns true if the reference points to an object that
5344 // can move in an incremental collection.
5345 bool G1CollectedHeap::is_scavengable(oop obj) {
5346   HeapRegion* hr = heap_region_containing(obj);
5347   return !hr->is_pinned();
5348 }
5349 
5350 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5351   guarantee(nm != NULL, "sanity");
5352   RegisterNMethodOopClosure reg_cl(this, nm);
5353   nm->oops_do(&reg_cl);
5354 }
5355 
5356 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5357   guarantee(nm != NULL, "sanity");
5358   UnregisterNMethodOopClosure reg_cl(this, nm);
5359   nm->oops_do(&reg_cl, true);
5360 }
5361 
5362 void G1CollectedHeap::purge_code_root_memory() {
5363   double purge_start = os::elapsedTime();
5364   G1CodeRootSet::purge();
5365   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5366   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5367 }
5368 
5369 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5370   G1CollectedHeap* _g1h;
5371 
5372 public:
5373   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5374     _g1h(g1h) {}
5375 
5376   void do_code_blob(CodeBlob* cb) {
5377     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5378     if (nm == NULL) {
5379       return;
5380     }
5381 
5382     if (ScavengeRootsInCode) {
5383       _g1h->register_nmethod(nm);
5384     }
5385   }
5386 };
5387 
5388 void G1CollectedHeap::rebuild_strong_code_roots() {
5389   RebuildStrongCodeRootClosure blob_cl(this);
5390   CodeCache::blobs_do(&blob_cl);
5391 }
5392 
5393 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5394   GrowableArray<GCMemoryManager*> memory_managers(2);
5395   memory_managers.append(&_memory_manager);
5396   memory_managers.append(&_full_gc_memory_manager);
5397   return memory_managers;
5398 }
5399 
5400 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5401   GrowableArray<MemoryPool*> memory_pools(3);
5402   memory_pools.append(_eden_pool);
5403   memory_pools.append(_survivor_pool);
5404   memory_pools.append(_old_pool);
5405   return memory_pools;
5406 }