1 /*
   2  * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/metadataOnStackMark.hpp"
  27 #include "classfile/stringTable.hpp"
  28 #include "classfile/symbolTable.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "gc/g1/bufferingOopClosure.hpp"
  32 #include "gc/g1/concurrentMarkThread.inline.hpp"
  33 #include "gc/g1/g1Allocator.inline.hpp"
  34 #include "gc/g1/g1CollectedHeap.inline.hpp"
  35 #include "gc/g1/g1CollectionSet.hpp"
  36 #include "gc/g1/g1CollectorPolicy.hpp"
  37 #include "gc/g1/g1CollectorState.hpp"
  38 #include "gc/g1/g1ConcurrentRefine.hpp"
  39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
  40 #include "gc/g1/g1DefaultPolicy.hpp"
  41 #include "gc/g1/g1EvacStats.inline.hpp"
  42 #include "gc/g1/g1FullCollector.hpp"
  43 #include "gc/g1/g1GCPhaseTimes.hpp"
  44 #include "gc/g1/g1HeapSizingPolicy.hpp"
  45 #include "gc/g1/g1HeapTransition.hpp"
  46 #include "gc/g1/g1HeapVerifier.hpp"
  47 #include "gc/g1/g1HotCardCache.hpp"
  48 #include "gc/g1/g1MemoryPool.hpp"
  49 #include "gc/g1/g1OopClosures.inline.hpp"
  50 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  51 #include "gc/g1/g1Policy.hpp"
  52 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  53 #include "gc/g1/g1RemSet.hpp"
  54 #include "gc/g1/g1RootClosures.hpp"
  55 #include "gc/g1/g1RootProcessor.hpp"
  56 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
  57 #include "gc/g1/g1StringDedup.hpp"
  58 #include "gc/g1/g1YCTypes.hpp"
  59 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  60 #include "gc/g1/heapRegion.inline.hpp"
  61 #include "gc/g1/heapRegionRemSet.hpp"
  62 #include "gc/g1/heapRegionSet.inline.hpp"
  63 #include "gc/g1/vm_operations_g1.hpp"
  64 #include "gc/shared/adaptiveSizePolicy.hpp"
  65 #include "gc/shared/gcHeapSummary.hpp"
  66 #include "gc/shared/gcId.hpp"
  67 #include "gc/shared/gcLocker.inline.hpp"
  68 #include "gc/shared/gcTimer.hpp"
  69 #include "gc/shared/gcTrace.hpp"
  70 #include "gc/shared/gcTraceTime.inline.hpp"
  71 #include "gc/shared/generationSpec.hpp"
  72 #include "gc/shared/isGCActiveMark.hpp"
  73 #include "gc/shared/preservedMarks.inline.hpp"
  74 #include "gc/shared/suspendibleThreadSet.hpp"
  75 #include "gc/shared/referenceProcessor.inline.hpp"
  76 #include "gc/shared/taskqueue.inline.hpp"
  77 #include "gc/shared/weakProcessor.hpp"
  78 #include "logging/log.hpp"
  79 #include "memory/allocation.hpp"
  80 #include "memory/iterator.hpp"
  81 #include "memory/resourceArea.hpp"
  82 #include "oops/oop.inline.hpp"
  83 #include "prims/resolvedMethodTable.hpp"
  84 #include "runtime/atomic.hpp"
  85 #include "runtime/init.hpp"
  86 #include "runtime/orderAccess.inline.hpp"
  87 #include "runtime/threadSMR.hpp"
  88 #include "runtime/vmThread.hpp"
  89 #include "utilities/align.hpp"
  90 #include "utilities/globalDefinitions.hpp"
  91 #include "utilities/stack.inline.hpp"
  92 
  93 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  94 
  95 // INVARIANTS/NOTES
  96 //
  97 // All allocation activity covered by the G1CollectedHeap interface is
  98 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  99 // and allocate_new_tlab, which are the "entry" points to the
 100 // allocation code from the rest of the JVM.  (Note that this does not
 101 // apply to TLAB allocation, which is not part of this interface: it
 102 // is done by clients of this interface.)
 103 
 104 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 105  private:
 106   size_t _num_dirtied;
 107   G1CollectedHeap* _g1h;
 108   G1CardTable* _g1_ct;
 109 
 110   HeapRegion* region_for_card(jbyte* card_ptr) const {
 111     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
 112   }
 113 
 114   bool will_become_free(HeapRegion* hr) const {
 115     // A region will be freed by free_collection_set if the region is in the
 116     // collection set and has not had an evacuation failure.
 117     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 118   }
 119 
 120  public:
 121   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 122     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
 123 
 124   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 125     HeapRegion* hr = region_for_card(card_ptr);
 126 
 127     // Should only dirty cards in regions that won't be freed.
 128     if (!will_become_free(hr)) {
 129       *card_ptr = G1CardTable::dirty_card_val();
 130       _num_dirtied++;
 131     }
 132 
 133     return true;
 134   }
 135 
 136   size_t num_dirtied()   const { return _num_dirtied; }
 137 };
 138 
 139 
 140 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 141   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 142 }
 143 
 144 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 145   // The from card cache is not the memory that is actually committed. So we cannot
 146   // take advantage of the zero_filled parameter.
 147   reset_from_card_cache(start_idx, num_regions);
 148 }
 149 
 150 
 151 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 152                                              MemRegion mr) {
 153   return new HeapRegion(hrs_index, bot(), mr);
 154 }
 155 
 156 // Private methods.
 157 
 158 HeapRegion*
 159 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 160   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 161   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 162     if (!_secondary_free_list.is_empty()) {
 163       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 164                                       "secondary_free_list has %u entries",
 165                                       _secondary_free_list.length());
 166       // It looks as if there are free regions available on the
 167       // secondary_free_list. Let's move them to the free_list and try
 168       // again to allocate from it.
 169       append_secondary_free_list();
 170 
 171       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 172              "empty we should have moved at least one entry to the free_list");
 173       HeapRegion* res = _hrm.allocate_free_region(is_old);
 174       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 175                                       "allocated " HR_FORMAT " from secondary_free_list",
 176                                       HR_FORMAT_PARAMS(res));
 177       return res;
 178     }
 179 
 180     // Wait here until we get notified either when (a) there are no
 181     // more free regions coming or (b) some regions have been moved on
 182     // the secondary_free_list.
 183     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 184   }
 185 
 186   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 187                                   "could not allocate from secondary_free_list");
 188   return NULL;
 189 }
 190 
 191 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 192   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 193          "the only time we use this to allocate a humongous region is "
 194          "when we are allocating a single humongous region");
 195 
 196   HeapRegion* res;
 197   if (G1StressConcRegionFreeing) {
 198     if (!_secondary_free_list.is_empty()) {
 199       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 200                                       "forced to look at the secondary_free_list");
 201       res = new_region_try_secondary_free_list(is_old);
 202       if (res != NULL) {
 203         return res;
 204       }
 205     }
 206   }
 207 
 208   res = _hrm.allocate_free_region(is_old);
 209 
 210   if (res == NULL) {
 211     log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 212                                     "res == NULL, trying the secondary_free_list");
 213     res = new_region_try_secondary_free_list(is_old);
 214   }
 215   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 216     // Currently, only attempts to allocate GC alloc regions set
 217     // do_expand to true. So, we should only reach here during a
 218     // safepoint. If this assumption changes we might have to
 219     // reconsider the use of _expand_heap_after_alloc_failure.
 220     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 221 
 222     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 223                               word_size * HeapWordSize);
 224 
 225     if (expand(word_size * HeapWordSize)) {
 226       // Given that expand() succeeded in expanding the heap, and we
 227       // always expand the heap by an amount aligned to the heap
 228       // region size, the free list should in theory not be empty.
 229       // In either case allocate_free_region() will check for NULL.
 230       res = _hrm.allocate_free_region(is_old);
 231     } else {
 232       _expand_heap_after_alloc_failure = false;
 233     }
 234   }
 235   return res;
 236 }
 237 
 238 HeapWord*
 239 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 240                                                            uint num_regions,
 241                                                            size_t word_size) {
 242   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 243   assert(is_humongous(word_size), "word_size should be humongous");
 244   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 245 
 246   // Index of last region in the series.
 247   uint last = first + num_regions - 1;
 248 
 249   // We need to initialize the region(s) we just discovered. This is
 250   // a bit tricky given that it can happen concurrently with
 251   // refinement threads refining cards on these regions and
 252   // potentially wanting to refine the BOT as they are scanning
 253   // those cards (this can happen shortly after a cleanup; see CR
 254   // 6991377). So we have to set up the region(s) carefully and in
 255   // a specific order.
 256 
 257   // The word size sum of all the regions we will allocate.
 258   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 259   assert(word_size <= word_size_sum, "sanity");
 260 
 261   // This will be the "starts humongous" region.
 262   HeapRegion* first_hr = region_at(first);
 263   // The header of the new object will be placed at the bottom of
 264   // the first region.
 265   HeapWord* new_obj = first_hr->bottom();
 266   // This will be the new top of the new object.
 267   HeapWord* obj_top = new_obj + word_size;
 268 
 269   // First, we need to zero the header of the space that we will be
 270   // allocating. When we update top further down, some refinement
 271   // threads might try to scan the region. By zeroing the header we
 272   // ensure that any thread that will try to scan the region will
 273   // come across the zero klass word and bail out.
 274   //
 275   // NOTE: It would not have been correct to have used
 276   // CollectedHeap::fill_with_object() and make the space look like
 277   // an int array. The thread that is doing the allocation will
 278   // later update the object header to a potentially different array
 279   // type and, for a very short period of time, the klass and length
 280   // fields will be inconsistent. This could cause a refinement
 281   // thread to calculate the object size incorrectly.
 282   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 283 
 284   // Next, pad out the unused tail of the last region with filler
 285   // objects, for improved usage accounting.
 286   // How many words we use for filler objects.
 287   size_t word_fill_size = word_size_sum - word_size;
 288 
 289   // How many words memory we "waste" which cannot hold a filler object.
 290   size_t words_not_fillable = 0;
 291 
 292   if (word_fill_size >= min_fill_size()) {
 293     fill_with_objects(obj_top, word_fill_size);
 294   } else if (word_fill_size > 0) {
 295     // We have space to fill, but we cannot fit an object there.
 296     words_not_fillable = word_fill_size;
 297     word_fill_size = 0;
 298   }
 299 
 300   // We will set up the first region as "starts humongous". This
 301   // will also update the BOT covering all the regions to reflect
 302   // that there is a single object that starts at the bottom of the
 303   // first region.
 304   first_hr->set_starts_humongous(obj_top, word_fill_size);
 305   // Then, if there are any, we will set up the "continues
 306   // humongous" regions.
 307   HeapRegion* hr = NULL;
 308   for (uint i = first + 1; i <= last; ++i) {
 309     hr = region_at(i);
 310     hr->set_continues_humongous(first_hr);
 311   }
 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) {
 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, word_size);
 430     assert(result != NULL, "it should always return a valid result");
 431 
 432     // A successful humongous object allocation changes the used space
 433     // information of the old generation so we need to recalculate the
 434     // sizes and update the jstat counters here.
 435     g1mm()->update_sizes();
 436   }
 437 
 438   _verifier->verify_region_sets_optional();
 439 
 440   return result;
 441 }
 442 
 443 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 444   assert_heap_not_locked_and_not_at_safepoint();
 445   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 446 
 447   return attempt_allocation(word_size);
 448 }
 449 
 450 HeapWord*
 451 G1CollectedHeap::mem_allocate(size_t word_size,
 452                               bool*  gc_overhead_limit_was_exceeded) {
 453   assert_heap_not_locked_and_not_at_safepoint();
 454 
 455   if (is_humongous(word_size)) {
 456     return attempt_allocation_humongous(word_size);
 457   }
 458   return attempt_allocation(word_size);
 459 }
 460 
 461 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 462   ResourceMark rm; // For retrieving the thread names in log messages.
 463 
 464   // Make sure you read the note in attempt_allocation_humongous().
 465 
 466   assert_heap_not_locked_and_not_at_safepoint();
 467   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 468          "be called for humongous allocation requests");
 469 
 470   // We should only get here after the first-level allocation attempt
 471   // (attempt_allocation()) failed to allocate.
 472 
 473   // We will loop until a) we manage to successfully perform the
 474   // allocation or b) we successfully schedule a collection which
 475   // fails to perform the allocation. b) is the only case when we'll
 476   // return NULL.
 477   HeapWord* result = NULL;
 478   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 479     bool should_try_gc;
 480     uint gc_count_before;
 481 
 482     {
 483       MutexLockerEx x(Heap_lock);
 484       result = _allocator->attempt_allocation_locked(word_size);
 485       if (result != NULL) {
 486         return result;
 487       }
 488 
 489       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 490       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 491       // waiting because the GCLocker is active to not wait too long.
 492       if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
 493         // No need for an ergo message here, can_expand_young_list() does this when
 494         // it returns true.
 495         result = _allocator->attempt_allocation_force(word_size);
 496         if (result != NULL) {
 497           return result;
 498         }
 499       }
 500       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 501       // the GCLocker initiated GC has been performed and then retry. This includes
 502       // the case when the GC Locker is not active but has not been performed.
 503       should_try_gc = !GCLocker::needs_gc();
 504       // Read the GC count while still holding the Heap_lock.
 505       gc_count_before = total_collections();
 506     }
 507 
 508     if (should_try_gc) {
 509       bool succeeded;
 510       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 511                                    GCCause::_g1_inc_collection_pause);
 512       if (result != NULL) {
 513         assert(succeeded, "only way to get back a non-NULL result");
 514         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 515                              Thread::current()->name(), p2i(result));
 516         return result;
 517       }
 518 
 519       if (succeeded) {
 520         // We successfully scheduled a collection which failed to allocate. No
 521         // point in trying to allocate further. We'll just return NULL.
 522         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 523                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 524         return NULL;
 525       }
 526       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 527                            Thread::current()->name(), word_size);
 528     } else {
 529       // Failed to schedule a collection.
 530       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 531         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 532                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 533         return NULL;
 534       }
 535       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 536       // The GCLocker is either active or the GCLocker initiated
 537       // GC has not yet been performed. Stall until it is and
 538       // then retry the allocation.
 539       GCLocker::stall_until_clear();
 540       gclocker_retry_count += 1;
 541     }
 542 
 543     // We can reach here if we were unsuccessful in scheduling a
 544     // collection (because another thread beat us to it) or if we were
 545     // stalled due to the GC locker. In either can we should retry the
 546     // allocation attempt in case another thread successfully
 547     // performed a collection and reclaimed enough space. We do the
 548     // first attempt (without holding the Heap_lock) here and the
 549     // follow-on attempt will be at the start of the next loop
 550     // iteration (after taking the Heap_lock).
 551 
 552     result = _allocator->attempt_allocation(word_size);
 553     if (result != NULL) {
 554       return result;
 555     }
 556 
 557     // Give a warning if we seem to be looping forever.
 558     if ((QueuedAllocationWarningCount > 0) &&
 559         (try_count % QueuedAllocationWarningCount == 0)) {
 560       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 561                              Thread::current()->name(), try_count, word_size);
 562     }
 563   }
 564 
 565   ShouldNotReachHere();
 566   return NULL;
 567 }
 568 
 569 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 570   assert_at_safepoint_on_vm_thread();
 571   if (_archive_allocator == NULL) {
 572     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 573   }
 574 }
 575 
 576 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 577   // Allocations in archive regions cannot be of a size that would be considered
 578   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 579   // may be different at archive-restore time.
 580   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 581 }
 582 
 583 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 584   assert_at_safepoint_on_vm_thread();
 585   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 586   if (is_archive_alloc_too_large(word_size)) {
 587     return NULL;
 588   }
 589   return _archive_allocator->archive_mem_allocate(word_size);
 590 }
 591 
 592 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 593                                               size_t end_alignment_in_bytes) {
 594   assert_at_safepoint_on_vm_thread();
 595   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 596 
 597   // Call complete_archive to do the real work, filling in the MemRegion
 598   // array with the archive regions.
 599   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 600   delete _archive_allocator;
 601   _archive_allocator = NULL;
 602 }
 603 
 604 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 605   assert(ranges != NULL, "MemRegion array NULL");
 606   assert(count != 0, "No MemRegions provided");
 607   MemRegion reserved = _hrm.reserved();
 608   for (size_t i = 0; i < count; i++) {
 609     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 610       return false;
 611     }
 612   }
 613   return true;
 614 }
 615 
 616 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 617                                             size_t count,
 618                                             bool open) {
 619   assert(!is_init_completed(), "Expect to be called at JVM init time");
 620   assert(ranges != NULL, "MemRegion array NULL");
 621   assert(count != 0, "No MemRegions provided");
 622   MutexLockerEx x(Heap_lock);
 623 
 624   MemRegion reserved = _hrm.reserved();
 625   HeapWord* prev_last_addr = NULL;
 626   HeapRegion* prev_last_region = NULL;
 627 
 628   // Temporarily disable pretouching of heap pages. This interface is used
 629   // when mmap'ing archived heap data in, so pre-touching is wasted.
 630   FlagSetting fs(AlwaysPreTouch, false);
 631 
 632   // Enable archive object checking used by G1MarkSweep. We have to let it know
 633   // about each archive range, so that objects in those ranges aren't marked.
 634   G1ArchiveAllocator::enable_archive_object_check();
 635 
 636   // For each specified MemRegion range, allocate the corresponding G1
 637   // regions and mark them as archive regions. We expect the ranges
 638   // in ascending starting address order, without overlap.
 639   for (size_t i = 0; i < count; i++) {
 640     MemRegion curr_range = ranges[i];
 641     HeapWord* start_address = curr_range.start();
 642     size_t word_size = curr_range.word_size();
 643     HeapWord* last_address = curr_range.last();
 644     size_t commits = 0;
 645 
 646     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 647               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 648               p2i(start_address), p2i(last_address));
 649     guarantee(start_address > prev_last_addr,
 650               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 651               p2i(start_address), p2i(prev_last_addr));
 652     prev_last_addr = last_address;
 653 
 654     // Check for ranges that start in the same G1 region in which the previous
 655     // range ended, and adjust the start address so we don't try to allocate
 656     // the same region again. If the current range is entirely within that
 657     // region, skip it, just adjusting the recorded top.
 658     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 659     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 660       start_address = start_region->end();
 661       if (start_address > last_address) {
 662         increase_used(word_size * HeapWordSize);
 663         start_region->set_top(last_address + 1);
 664         continue;
 665       }
 666       start_region->set_top(start_address);
 667       curr_range = MemRegion(start_address, last_address + 1);
 668       start_region = _hrm.addr_to_region(start_address);
 669     }
 670 
 671     // Perform the actual region allocation, exiting if it fails.
 672     // Then note how much new space we have allocated.
 673     if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
 674       return false;
 675     }
 676     increase_used(word_size * HeapWordSize);
 677     if (commits != 0) {
 678       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 679                                 HeapRegion::GrainWords * HeapWordSize * commits);
 680 
 681     }
 682 
 683     // Mark each G1 region touched by the range as archive, add it to
 684     // the old set, and set top.
 685     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 686     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 687     prev_last_region = last_region;
 688 
 689     while (curr_region != NULL) {
 690       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 691              "Region already in use (index %u)", curr_region->hrm_index());
 692       if (open) {
 693         curr_region->set_open_archive();
 694       } else {
 695         curr_region->set_closed_archive();
 696       }
 697       _hr_printer.alloc(curr_region);
 698       _old_set.add(curr_region);
 699       HeapWord* top;
 700       HeapRegion* next_region;
 701       if (curr_region != last_region) {
 702         top = curr_region->end();
 703         next_region = _hrm.next_region_in_heap(curr_region);
 704       } else {
 705         top = last_address + 1;
 706         next_region = NULL;
 707       }
 708       curr_region->set_top(top);
 709       curr_region->set_first_dead(top);
 710       curr_region->set_end_of_live(top);
 711       curr_region = next_region;
 712     }
 713 
 714     // Notify mark-sweep of the archive
 715     G1ArchiveAllocator::set_range_archive(curr_range, open);
 716   }
 717   return true;
 718 }
 719 
 720 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 721   assert(!is_init_completed(), "Expect to be called at JVM init time");
 722   assert(ranges != NULL, "MemRegion array NULL");
 723   assert(count != 0, "No MemRegions provided");
 724   MemRegion reserved = _hrm.reserved();
 725   HeapWord *prev_last_addr = NULL;
 726   HeapRegion* prev_last_region = NULL;
 727 
 728   // For each MemRegion, create filler objects, if needed, in the G1 regions
 729   // that contain the address range. The address range actually within the
 730   // MemRegion will not be modified. That is assumed to have been initialized
 731   // elsewhere, probably via an mmap of archived heap data.
 732   MutexLockerEx x(Heap_lock);
 733   for (size_t i = 0; i < count; i++) {
 734     HeapWord* start_address = ranges[i].start();
 735     HeapWord* last_address = ranges[i].last();
 736 
 737     assert(reserved.contains(start_address) && reserved.contains(last_address),
 738            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 739            p2i(start_address), p2i(last_address));
 740     assert(start_address > prev_last_addr,
 741            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 742            p2i(start_address), p2i(prev_last_addr));
 743 
 744     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 745     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 746     HeapWord* bottom_address = start_region->bottom();
 747 
 748     // Check for a range beginning in the same region in which the
 749     // previous one ended.
 750     if (start_region == prev_last_region) {
 751       bottom_address = prev_last_addr + 1;
 752     }
 753 
 754     // Verify that the regions were all marked as archive regions by
 755     // alloc_archive_regions.
 756     HeapRegion* curr_region = start_region;
 757     while (curr_region != NULL) {
 758       guarantee(curr_region->is_archive(),
 759                 "Expected archive region at index %u", curr_region->hrm_index());
 760       if (curr_region != last_region) {
 761         curr_region = _hrm.next_region_in_heap(curr_region);
 762       } else {
 763         curr_region = NULL;
 764       }
 765     }
 766 
 767     prev_last_addr = last_address;
 768     prev_last_region = last_region;
 769 
 770     // Fill the memory below the allocated range with dummy object(s),
 771     // if the region bottom does not match the range start, or if the previous
 772     // range ended within the same G1 region, and there is a gap.
 773     if (start_address != bottom_address) {
 774       size_t fill_size = pointer_delta(start_address, bottom_address);
 775       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 776       increase_used(fill_size * HeapWordSize);
 777     }
 778   }
 779 }
 780 
 781 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) {
 782   assert_heap_not_locked_and_not_at_safepoint();
 783   assert(!is_humongous(word_size), "attempt_allocation() should not "
 784          "be called for humongous allocation requests");
 785 
 786   HeapWord* result = _allocator->attempt_allocation(word_size);
 787 
 788   if (result == NULL) {
 789     result = attempt_allocation_slow(word_size);
 790   }
 791   assert_heap_not_locked();
 792   if (result != NULL) {
 793     dirty_young_block(result, word_size);
 794   }
 795   return result;
 796 }
 797 
 798 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 799   assert(!is_init_completed(), "Expect to be called at JVM init time");
 800   assert(ranges != NULL, "MemRegion array NULL");
 801   assert(count != 0, "No MemRegions provided");
 802   MemRegion reserved = _hrm.reserved();
 803   HeapWord* prev_last_addr = NULL;
 804   HeapRegion* prev_last_region = NULL;
 805   size_t size_used = 0;
 806   size_t uncommitted_regions = 0;
 807 
 808   // For each Memregion, free the G1 regions that constitute it, and
 809   // notify mark-sweep that the range is no longer to be considered 'archive.'
 810   MutexLockerEx x(Heap_lock);
 811   for (size_t i = 0; i < count; i++) {
 812     HeapWord* start_address = ranges[i].start();
 813     HeapWord* last_address = ranges[i].last();
 814 
 815     assert(reserved.contains(start_address) && reserved.contains(last_address),
 816            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 817            p2i(start_address), p2i(last_address));
 818     assert(start_address > prev_last_addr,
 819            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 820            p2i(start_address), p2i(prev_last_addr));
 821     size_used += ranges[i].byte_size();
 822     prev_last_addr = last_address;
 823 
 824     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 825     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 826 
 827     // Check for ranges that start in the same G1 region in which the previous
 828     // range ended, and adjust the start address so we don't try to free
 829     // the same region again. If the current range is entirely within that
 830     // region, skip it.
 831     if (start_region == prev_last_region) {
 832       start_address = start_region->end();
 833       if (start_address > last_address) {
 834         continue;
 835       }
 836       start_region = _hrm.addr_to_region(start_address);
 837     }
 838     prev_last_region = last_region;
 839 
 840     // After verifying that each region was marked as an archive region by
 841     // alloc_archive_regions, set it free and empty and uncommit it.
 842     HeapRegion* curr_region = start_region;
 843     while (curr_region != NULL) {
 844       guarantee(curr_region->is_archive(),
 845                 "Expected archive region at index %u", curr_region->hrm_index());
 846       uint curr_index = curr_region->hrm_index();
 847       _old_set.remove(curr_region);
 848       curr_region->set_free();
 849       curr_region->set_top(curr_region->bottom());
 850       if (curr_region != last_region) {
 851         curr_region = _hrm.next_region_in_heap(curr_region);
 852       } else {
 853         curr_region = NULL;
 854       }
 855       _hrm.shrink_at(curr_index, 1);
 856       uncommitted_regions++;
 857     }
 858 
 859     // Notify mark-sweep that this is no longer an archive range.
 860     G1ArchiveAllocator::set_range_archive(ranges[i], false);
 861   }
 862 
 863   if (uncommitted_regions != 0) {
 864     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 865                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 866   }
 867   decrease_used(size_used);
 868 }
 869 
 870 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 871   ResourceMark rm; // For retrieving the thread names in log messages.
 872 
 873   // The structure of this method has a lot of similarities to
 874   // attempt_allocation_slow(). The reason these two were not merged
 875   // into a single one is that such a method would require several "if
 876   // allocation is not humongous do this, otherwise do that"
 877   // conditional paths which would obscure its flow. In fact, an early
 878   // version of this code did use a unified method which was harder to
 879   // follow and, as a result, it had subtle bugs that were hard to
 880   // track down. So keeping these two methods separate allows each to
 881   // be more readable. It will be good to keep these two in sync as
 882   // much as possible.
 883 
 884   assert_heap_not_locked_and_not_at_safepoint();
 885   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 886          "should only be called for humongous allocations");
 887 
 888   // Humongous objects can exhaust the heap quickly, so we should check if we
 889   // need to start a marking cycle at each humongous object allocation. We do
 890   // the check before we do the actual allocation. The reason for doing it
 891   // before the allocation is that we avoid having to keep track of the newly
 892   // allocated memory while we do a GC.
 893   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 894                                            word_size)) {
 895     collect(GCCause::_g1_humongous_allocation);
 896   }
 897 
 898   // We will loop until a) we manage to successfully perform the
 899   // allocation or b) we successfully schedule a collection which
 900   // fails to perform the allocation. b) is the only case when we'll
 901   // return NULL.
 902   HeapWord* result = NULL;
 903   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 904     bool should_try_gc;
 905     uint gc_count_before;
 906 
 907 
 908     {
 909       MutexLockerEx x(Heap_lock);
 910 
 911       // Given that humongous objects are not allocated in young
 912       // regions, we'll first try to do the allocation without doing a
 913       // collection hoping that there's enough space in the heap.
 914       result = humongous_obj_allocate(word_size);
 915       if (result != NULL) {
 916         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 917         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 918         return result;
 919       }
 920 
 921       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 922       // the GCLocker initiated GC has been performed and then retry. This includes
 923       // the case when the GC Locker is not active but has not been performed.
 924       should_try_gc = !GCLocker::needs_gc();
 925       // Read the GC count while still holding the Heap_lock.
 926       gc_count_before = total_collections();
 927     }
 928 
 929     if (should_try_gc) {
 930       bool succeeded;
 931       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 932                                    GCCause::_g1_humongous_allocation);
 933       if (result != NULL) {
 934         assert(succeeded, "only way to get back a non-NULL result");
 935         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 936                              Thread::current()->name(), p2i(result));
 937         return result;
 938       }
 939 
 940       if (succeeded) {
 941         // We successfully scheduled a collection which failed to allocate. No
 942         // point in trying to allocate further. We'll just return NULL.
 943         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 944                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 945         return NULL;
 946       }
 947       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 948                            Thread::current()->name(), word_size);
 949     } else {
 950       // Failed to schedule a collection.
 951       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 952         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 953                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 954         return NULL;
 955       }
 956       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 957       // The GCLocker is either active or the GCLocker initiated
 958       // GC has not yet been performed. Stall until it is and
 959       // then retry the allocation.
 960       GCLocker::stall_until_clear();
 961       gclocker_retry_count += 1;
 962     }
 963 
 964 
 965     // We can reach here if we were unsuccessful in scheduling a
 966     // collection (because another thread beat us to it) or if we were
 967     // stalled due to the GC locker. In either can we should retry the
 968     // allocation attempt in case another thread successfully
 969     // performed a collection and reclaimed enough space.
 970     // Humongous object allocation always needs a lock, so we wait for the retry
 971     // in the next iteration of the loop, unlike for the regular iteration case.
 972     // Give a warning if we seem to be looping forever.
 973 
 974     if ((QueuedAllocationWarningCount > 0) &&
 975         (try_count % QueuedAllocationWarningCount == 0)) {
 976       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 977                              Thread::current()->name(), try_count, word_size);
 978     }
 979   }
 980 
 981   ShouldNotReachHere();
 982   return NULL;
 983 }
 984 
 985 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 986                                                            bool expect_null_mutator_alloc_region) {
 987   assert_at_safepoint_on_vm_thread();
 988   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 989          "the current alloc region was unexpectedly found to be non-NULL");
 990 
 991   if (!is_humongous(word_size)) {
 992     return _allocator->attempt_allocation_locked(word_size);
 993   } else {
 994     HeapWord* result = humongous_obj_allocate(word_size);
 995     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
 996       collector_state()->set_initiate_conc_mark_if_possible(true);
 997     }
 998     return result;
 999   }
1000 
1001   ShouldNotReachHere();
1002 }
1003 
1004 class PostCompactionPrinterClosure: public HeapRegionClosure {
1005 private:
1006   G1HRPrinter* _hr_printer;
1007 public:
1008   bool do_heap_region(HeapRegion* hr) {
1009     assert(!hr->is_young(), "not expecting to find young regions");
1010     _hr_printer->post_compaction(hr);
1011     return false;
1012   }
1013 
1014   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1015     : _hr_printer(hr_printer) { }
1016 };
1017 
1018 void G1CollectedHeap::print_hrm_post_compaction() {
1019   if (_hr_printer.is_active()) {
1020     PostCompactionPrinterClosure cl(hr_printer());
1021     heap_region_iterate(&cl);
1022   }
1023 }
1024 
1025 void G1CollectedHeap::abort_concurrent_cycle() {
1026   // Note: When we have a more flexible GC logging framework that
1027   // allows us to add optional attributes to a GC log record we
1028   // could consider timing and reporting how long we wait in the
1029   // following two methods.
1030   wait_while_free_regions_coming();
1031   // If we start the compaction before the CM threads finish
1032   // scanning the root regions we might trip them over as we'll
1033   // be moving objects / updating references. So let's wait until
1034   // they are done. By telling them to abort, they should complete
1035   // early.
1036   _cm->root_regions()->abort();
1037   _cm->root_regions()->wait_until_scan_finished();
1038   append_secondary_free_list_if_not_empty_with_lock();
1039 
1040   // Disable discovery and empty the discovered lists
1041   // for the CM ref processor.
1042   ref_processor_cm()->disable_discovery();
1043   ref_processor_cm()->abandon_partial_discovery();
1044   ref_processor_cm()->verify_no_references_recorded();
1045 
1046   // Abandon current iterations of concurrent marking and concurrent
1047   // refinement, if any are in progress.
1048   concurrent_mark()->abort();
1049 }
1050 
1051 void G1CollectedHeap::prepare_heap_for_full_collection() {
1052   // Make sure we'll choose a new allocation region afterwards.
1053   _allocator->release_mutator_alloc_region();
1054   _allocator->abandon_gc_alloc_regions();
1055   g1_rem_set()->cleanupHRRS();
1056 
1057   // We may have added regions to the current incremental collection
1058   // set between the last GC or pause and now. We need to clear the
1059   // incremental collection set and then start rebuilding it afresh
1060   // after this full GC.
1061   abandon_collection_set(collection_set());
1062 
1063   tear_down_region_sets(false /* free_list_only */);
1064   collector_state()->set_gcs_are_young(true);
1065 }
1066 
1067 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1068   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1069   assert(used() == recalculate_used(), "Should be equal");
1070   _verifier->verify_region_sets_optional();
1071   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1072   _verifier->check_bitmaps("Full GC Start");
1073 }
1074 
1075 void G1CollectedHeap::prepare_heap_for_mutators() {
1076   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1077   ClassLoaderDataGraph::purge();
1078   MetaspaceAux::verify_metrics();
1079 
1080   // Prepare heap for normal collections.
1081   assert(num_free_regions() == 0, "we should not have added any free regions");
1082   rebuild_region_sets(false /* free_list_only */);
1083   abort_refinement();
1084   resize_if_necessary_after_full_collection();
1085 
1086   // Rebuild the strong code root lists for each region
1087   rebuild_strong_code_roots();
1088 
1089   // Start a new incremental collection set for the next pause
1090   start_new_collection_set();
1091 
1092   _allocator->init_mutator_alloc_region();
1093 
1094   // Post collection state updates.
1095   MetaspaceGC::compute_new_size();
1096 }
1097 
1098 void G1CollectedHeap::abort_refinement() {
1099   if (_hot_card_cache->use_cache()) {
1100     _hot_card_cache->reset_hot_cache();
1101   }
1102 
1103   // Discard all remembered set updates.
1104   JavaThread::dirty_card_queue_set().abandon_logs();
1105   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1106 }
1107 
1108 void G1CollectedHeap::verify_after_full_collection() {
1109   check_gc_time_stamps();
1110   _hrm.verify_optional();
1111   _verifier->verify_region_sets_optional();
1112   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1113   // Clear the previous marking bitmap, if needed for bitmap verification.
1114   // Note we cannot do this when we clear the next marking bitmap in
1115   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1116   // objects marked during a full GC against the previous bitmap.
1117   // But we need to clear it before calling check_bitmaps below since
1118   // the full GC has compacted objects and updated TAMS but not updated
1119   // the prev bitmap.
1120   if (G1VerifyBitmaps) {
1121     GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1122     _cm->clear_prev_bitmap(workers());
1123   }
1124   _verifier->check_bitmaps("Full GC End");
1125 
1126   // At this point there should be no regions in the
1127   // entire heap tagged as young.
1128   assert(check_young_list_empty(), "young list should be empty at this point");
1129 
1130   // Note: since we've just done a full GC, concurrent
1131   // marking is no longer active. Therefore we need not
1132   // re-enable reference discovery for the CM ref processor.
1133   // That will be done at the start of the next marking cycle.
1134   // We also know that the STW processor should no longer
1135   // discover any new references.
1136   assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1137   assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1138   ref_processor_stw()->verify_no_references_recorded();
1139   ref_processor_cm()->verify_no_references_recorded();
1140 }
1141 
1142 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1143   // Post collection logging.
1144   // We should do this after we potentially resize the heap so
1145   // that all the COMMIT / UNCOMMIT events are generated before
1146   // the compaction events.
1147   print_hrm_post_compaction();
1148   heap_transition->print();
1149   print_heap_after_gc();
1150   print_heap_regions();
1151 #ifdef TRACESPINNING
1152   ParallelTaskTerminator::print_termination_counts();
1153 #endif
1154 }
1155 
1156 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1157                                          bool clear_all_soft_refs) {
1158   assert_at_safepoint_on_vm_thread();
1159 
1160   if (GCLocker::check_active_before_gc()) {
1161     // Full GC was not completed.
1162     return false;
1163   }
1164 
1165   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1166       soft_ref_policy()->should_clear_all_soft_refs();
1167 
1168   G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1169   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1170 
1171   collector.prepare_collection();
1172   collector.collect();
1173   collector.complete_collection();
1174 
1175   // Full collection was successfully completed.
1176   return true;
1177 }
1178 
1179 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1180   // Currently, there is no facility in the do_full_collection(bool) API to notify
1181   // the caller that the collection did not succeed (e.g., because it was locked
1182   // out by the GC locker). So, right now, we'll ignore the return value.
1183   bool dummy = do_full_collection(true,                /* explicit_gc */
1184                                   clear_all_soft_refs);
1185 }
1186 
1187 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1188   // Capacity, free and used after the GC counted as full regions to
1189   // include the waste in the following calculations.
1190   const size_t capacity_after_gc = capacity();
1191   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1192 
1193   // This is enforced in arguments.cpp.
1194   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1195          "otherwise the code below doesn't make sense");
1196 
1197   // We don't have floating point command-line arguments
1198   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1199   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1200   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1201   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1202 
1203   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1204   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1205 
1206   // We have to be careful here as these two calculations can overflow
1207   // 32-bit size_t's.
1208   double used_after_gc_d = (double) used_after_gc;
1209   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1210   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1211 
1212   // Let's make sure that they are both under the max heap size, which
1213   // by default will make them fit into a size_t.
1214   double desired_capacity_upper_bound = (double) max_heap_size;
1215   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1216                                     desired_capacity_upper_bound);
1217   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1218                                     desired_capacity_upper_bound);
1219 
1220   // We can now safely turn them into size_t's.
1221   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1222   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1223 
1224   // This assert only makes sense here, before we adjust them
1225   // with respect to the min and max heap size.
1226   assert(minimum_desired_capacity <= maximum_desired_capacity,
1227          "minimum_desired_capacity = " SIZE_FORMAT ", "
1228          "maximum_desired_capacity = " SIZE_FORMAT,
1229          minimum_desired_capacity, maximum_desired_capacity);
1230 
1231   // Should not be greater than the heap max size. No need to adjust
1232   // it with respect to the heap min size as it's a lower bound (i.e.,
1233   // we'll try to make the capacity larger than it, not smaller).
1234   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1235   // Should not be less than the heap min size. No need to adjust it
1236   // with respect to the heap max size as it's an upper bound (i.e.,
1237   // we'll try to make the capacity smaller than it, not greater).
1238   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1239 
1240   if (capacity_after_gc < minimum_desired_capacity) {
1241     // Don't expand unless it's significant
1242     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1243 
1244     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1245                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1246                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1247                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1248 
1249     expand(expand_bytes, _workers);
1250 
1251     // No expansion, now see if we want to shrink
1252   } else if (capacity_after_gc > maximum_desired_capacity) {
1253     // Capacity too large, compute shrinking size
1254     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1255 
1256     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1257                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1258                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1259                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1260 
1261     shrink(shrink_bytes);
1262   }
1263 }
1264 
1265 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1266                                                             bool do_gc,
1267                                                             bool clear_all_soft_refs,
1268                                                             bool expect_null_mutator_alloc_region,
1269                                                             bool* gc_succeeded) {
1270   *gc_succeeded = true;
1271   // Let's attempt the allocation first.
1272   HeapWord* result =
1273     attempt_allocation_at_safepoint(word_size,
1274                                     expect_null_mutator_alloc_region);
1275   if (result != NULL) {
1276     return result;
1277   }
1278 
1279   // In a G1 heap, we're supposed to keep allocation from failing by
1280   // incremental pauses.  Therefore, at least for now, we'll favor
1281   // expansion over collection.  (This might change in the future if we can
1282   // do something smarter than full collection to satisfy a failed alloc.)
1283   result = expand_and_allocate(word_size);
1284   if (result != NULL) {
1285     return result;
1286   }
1287 
1288   if (do_gc) {
1289     // Expansion didn't work, we'll try to do a Full GC.
1290     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1291                                        clear_all_soft_refs);
1292   }
1293 
1294   return NULL;
1295 }
1296 
1297 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1298                                                      bool* succeeded) {
1299   assert_at_safepoint_on_vm_thread();
1300 
1301   // Attempts to allocate followed by Full GC.
1302   HeapWord* result =
1303     satisfy_failed_allocation_helper(word_size,
1304                                      true,  /* do_gc */
1305                                      false, /* clear_all_soft_refs */
1306                                      false, /* expect_null_mutator_alloc_region */
1307                                      succeeded);
1308 
1309   if (result != NULL || !*succeeded) {
1310     return result;
1311   }
1312 
1313   // Attempts to allocate followed by Full GC that will collect all soft references.
1314   result = satisfy_failed_allocation_helper(word_size,
1315                                             true, /* do_gc */
1316                                             true, /* clear_all_soft_refs */
1317                                             true, /* expect_null_mutator_alloc_region */
1318                                             succeeded);
1319 
1320   if (result != NULL || !*succeeded) {
1321     return result;
1322   }
1323 
1324   // Attempts to allocate, no GC
1325   result = satisfy_failed_allocation_helper(word_size,
1326                                             false, /* do_gc */
1327                                             false, /* clear_all_soft_refs */
1328                                             true,  /* expect_null_mutator_alloc_region */
1329                                             succeeded);
1330 
1331   if (result != NULL) {
1332     return result;
1333   }
1334 
1335   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1336          "Flag should have been handled and cleared prior to this point");
1337 
1338   // What else?  We might try synchronous finalization later.  If the total
1339   // space available is large enough for the allocation, then a more
1340   // complete compaction phase than we've tried so far might be
1341   // appropriate.
1342   return NULL;
1343 }
1344 
1345 // Attempting to expand the heap sufficiently
1346 // to support an allocation of the given "word_size".  If
1347 // successful, perform the allocation and return the address of the
1348 // allocated block, or else "NULL".
1349 
1350 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1351   assert_at_safepoint_on_vm_thread();
1352 
1353   _verifier->verify_region_sets_optional();
1354 
1355   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1356   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1357                             word_size * HeapWordSize);
1358 
1359 
1360   if (expand(expand_bytes, _workers)) {
1361     _hrm.verify_optional();
1362     _verifier->verify_region_sets_optional();
1363     return attempt_allocation_at_safepoint(word_size,
1364                                            false /* expect_null_mutator_alloc_region */);
1365   }
1366   return NULL;
1367 }
1368 
1369 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1370   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1371   aligned_expand_bytes = align_up(aligned_expand_bytes,
1372                                        HeapRegion::GrainBytes);
1373 
1374   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1375                             expand_bytes, aligned_expand_bytes);
1376 
1377   if (is_maximal_no_gc()) {
1378     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1379     return false;
1380   }
1381 
1382   double expand_heap_start_time_sec = os::elapsedTime();
1383   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1384   assert(regions_to_expand > 0, "Must expand by at least one region");
1385 
1386   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1387   if (expand_time_ms != NULL) {
1388     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1389   }
1390 
1391   if (expanded_by > 0) {
1392     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1393     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1394     g1_policy()->record_new_heap_size(num_regions());
1395   } else {
1396     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1397 
1398     // The expansion of the virtual storage space was unsuccessful.
1399     // Let's see if it was because we ran out of swap.
1400     if (G1ExitOnExpansionFailure &&
1401         _hrm.available() >= regions_to_expand) {
1402       // We had head room...
1403       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1404     }
1405   }
1406   return regions_to_expand > 0;
1407 }
1408 
1409 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1410   size_t aligned_shrink_bytes =
1411     ReservedSpace::page_align_size_down(shrink_bytes);
1412   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1413                                          HeapRegion::GrainBytes);
1414   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1415 
1416   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1417   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1418 
1419 
1420   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",
1421                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1422   if (num_regions_removed > 0) {
1423     g1_policy()->record_new_heap_size(num_regions());
1424   } else {
1425     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1426   }
1427 }
1428 
1429 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1430   _verifier->verify_region_sets_optional();
1431 
1432   // We should only reach here at the end of a Full GC which means we
1433   // should not not be holding to any GC alloc regions. The method
1434   // below will make sure of that and do any remaining clean up.
1435   _allocator->abandon_gc_alloc_regions();
1436 
1437   // Instead of tearing down / rebuilding the free lists here, we
1438   // could instead use the remove_all_pending() method on free_list to
1439   // remove only the ones that we need to remove.
1440   tear_down_region_sets(true /* free_list_only */);
1441   shrink_helper(shrink_bytes);
1442   rebuild_region_sets(true /* free_list_only */);
1443 
1444   _hrm.verify_optional();
1445   _verifier->verify_region_sets_optional();
1446 }
1447 
1448 // Public methods.
1449 
1450 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1451   CollectedHeap(),
1452   _young_gen_sampling_thread(NULL),
1453   _collector_policy(collector_policy),
1454   _soft_ref_policy(),
1455   _card_table(NULL),
1456   _memory_manager("G1 Young Generation", "end of minor GC"),
1457   _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1458   _eden_pool(NULL),
1459   _survivor_pool(NULL),
1460   _old_pool(NULL),
1461   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1462   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1463   _g1_policy(new G1DefaultPolicy(_gc_timer_stw)),
1464   _collection_set(this, _g1_policy),
1465   _dirty_card_queue_set(false),
1466   _is_alive_closure_cm(this),
1467   _is_alive_closure_stw(this),
1468   _ref_processor_cm(NULL),
1469   _ref_processor_stw(NULL),
1470   _bot(NULL),
1471   _hot_card_cache(NULL),
1472   _g1_rem_set(NULL),
1473   _cr(NULL),
1474   _g1mm(NULL),
1475   _preserved_marks_set(true /* in_c_heap */),
1476   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1477   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1478   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1479   _humongous_reclaim_candidates(),
1480   _has_humongous_reclaim_candidates(false),
1481   _archive_allocator(NULL),
1482   _free_regions_coming(false),
1483   _gc_time_stamp(0),
1484   _summary_bytes_used(0),
1485   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1486   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1487   _expand_heap_after_alloc_failure(true),
1488   _old_marking_cycles_started(0),
1489   _old_marking_cycles_completed(0),
1490   _in_cset_fast_test() {
1491 
1492   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1493                           /* are_GC_task_threads */true,
1494                           /* are_ConcurrentGC_threads */false);
1495   _workers->initialize_workers();
1496   _verifier = new G1HeapVerifier(this);
1497 
1498   _allocator = new G1DefaultAllocator(this);
1499 
1500   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1501 
1502   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1503 
1504   // Override the default _filler_array_max_size so that no humongous filler
1505   // objects are created.
1506   _filler_array_max_size = _humongous_object_threshold_in_words;
1507 
1508   uint n_queues = ParallelGCThreads;
1509   _task_queues = new RefToScanQueueSet(n_queues);
1510 
1511   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1512 
1513   for (uint i = 0; i < n_queues; i++) {
1514     RefToScanQueue* q = new RefToScanQueue();
1515     q->initialize();
1516     _task_queues->register_queue(i, q);
1517     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1518   }
1519 
1520   // Initialize the G1EvacuationFailureALot counters and flags.
1521   NOT_PRODUCT(reset_evacuation_should_fail();)
1522 
1523   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1524 }
1525 
1526 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1527                                                                  size_t size,
1528                                                                  size_t translation_factor) {
1529   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1530   // Allocate a new reserved space, preferring to use large pages.
1531   ReservedSpace rs(size, preferred_page_size);
1532   G1RegionToSpaceMapper* result  =
1533     G1RegionToSpaceMapper::create_mapper(rs,
1534                                          size,
1535                                          rs.alignment(),
1536                                          HeapRegion::GrainBytes,
1537                                          translation_factor,
1538                                          mtGC);
1539 
1540   os::trace_page_sizes_for_requested_size(description,
1541                                           size,
1542                                           preferred_page_size,
1543                                           rs.alignment(),
1544                                           rs.base(),
1545                                           rs.size());
1546 
1547   return result;
1548 }
1549 
1550 jint G1CollectedHeap::initialize_concurrent_refinement() {
1551   jint ecode = JNI_OK;
1552   _cr = G1ConcurrentRefine::create(&ecode);
1553   return ecode;
1554 }
1555 
1556 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1557   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1558   if (_young_gen_sampling_thread->osthread() == NULL) {
1559     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1560     return JNI_ENOMEM;
1561   }
1562   return JNI_OK;
1563 }
1564 
1565 jint G1CollectedHeap::initialize() {
1566   os::enable_vtime();
1567 
1568   // Necessary to satisfy locking discipline assertions.
1569 
1570   MutexLocker x(Heap_lock);
1571 
1572   // While there are no constraints in the GC code that HeapWordSize
1573   // be any particular value, there are multiple other areas in the
1574   // system which believe this to be true (e.g. oop->object_size in some
1575   // cases incorrectly returns the size in wordSize units rather than
1576   // HeapWordSize).
1577   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1578 
1579   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1580   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1581   size_t heap_alignment = collector_policy()->heap_alignment();
1582 
1583   // Ensure that the sizes are properly aligned.
1584   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1585   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1586   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1587 
1588   // Reserve the maximum.
1589 
1590   // When compressed oops are enabled, the preferred heap base
1591   // is calculated by subtracting the requested size from the
1592   // 32Gb boundary and using the result as the base address for
1593   // heap reservation. If the requested size is not aligned to
1594   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1595   // into the ReservedHeapSpace constructor) then the actual
1596   // base of the reserved heap may end up differing from the
1597   // address that was requested (i.e. the preferred heap base).
1598   // If this happens then we could end up using a non-optimal
1599   // compressed oops mode.
1600 
1601   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1602                                                  heap_alignment);
1603 
1604   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1605 
1606   // Create the barrier set for the entire reserved region.
1607   G1CardTable* ct = new G1CardTable(reserved_region());
1608   ct->initialize();
1609   G1SATBCardTableLoggingModRefBS* bs = new G1SATBCardTableLoggingModRefBS(ct);
1610   bs->initialize();
1611   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1612   set_barrier_set(bs);
1613   _card_table = ct;
1614 
1615   // Create the hot card cache.
1616   _hot_card_cache = new G1HotCardCache(this);
1617 
1618   // Carve out the G1 part of the heap.
1619   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1620   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1621   G1RegionToSpaceMapper* heap_storage =
1622     G1RegionToSpaceMapper::create_mapper(g1_rs,
1623                                          g1_rs.size(),
1624                                          page_size,
1625                                          HeapRegion::GrainBytes,
1626                                          1,
1627                                          mtJavaHeap);
1628   os::trace_page_sizes("Heap",
1629                        collector_policy()->min_heap_byte_size(),
1630                        max_byte_size,
1631                        page_size,
1632                        heap_rs.base(),
1633                        heap_rs.size());
1634   heap_storage->set_mapping_changed_listener(&_listener);
1635 
1636   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1637   G1RegionToSpaceMapper* bot_storage =
1638     create_aux_memory_mapper("Block Offset Table",
1639                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1640                              G1BlockOffsetTable::heap_map_factor());
1641 
1642   G1RegionToSpaceMapper* cardtable_storage =
1643     create_aux_memory_mapper("Card Table",
1644                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1645                              G1CardTable::heap_map_factor());
1646 
1647   G1RegionToSpaceMapper* card_counts_storage =
1648     create_aux_memory_mapper("Card Counts Table",
1649                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1650                              G1CardCounts::heap_map_factor());
1651 
1652   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1653   G1RegionToSpaceMapper* prev_bitmap_storage =
1654     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1655   G1RegionToSpaceMapper* next_bitmap_storage =
1656     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1657 
1658   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1659   _card_table->initialize(cardtable_storage);
1660   // Do later initialization work for concurrent refinement.
1661   _hot_card_cache->initialize(card_counts_storage);
1662 
1663   // 6843694 - ensure that the maximum region index can fit
1664   // in the remembered set structures.
1665   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1666   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1667 
1668   // Also create a G1 rem set.
1669   _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1670   _g1_rem_set->initialize(max_capacity(), max_regions());
1671 
1672   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1673   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1674   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1675             "too many cards per region");
1676 
1677   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1678 
1679   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1680 
1681   {
1682     HeapWord* start = _hrm.reserved().start();
1683     HeapWord* end = _hrm.reserved().end();
1684     size_t granularity = HeapRegion::GrainBytes;
1685 
1686     _in_cset_fast_test.initialize(start, end, granularity);
1687     _humongous_reclaim_candidates.initialize(start, end, granularity);
1688   }
1689 
1690   // Create the G1ConcurrentMark data structure and thread.
1691   // (Must do this late, so that "max_regions" is defined.)
1692   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1693   if (_cm == NULL || !_cm->completed_initialization()) {
1694     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1695     return JNI_ENOMEM;
1696   }
1697   _cmThread = _cm->cm_thread();
1698 
1699   // Now expand into the initial heap size.
1700   if (!expand(init_byte_size, _workers)) {
1701     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1702     return JNI_ENOMEM;
1703   }
1704 
1705   // Perform any initialization actions delegated to the policy.
1706   g1_policy()->init(this, &_collection_set);
1707 
1708   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1709                                                SATB_Q_FL_lock,
1710                                                G1SATBProcessCompletedThreshold,
1711                                                Shared_SATB_Q_lock);
1712 
1713   jint ecode = initialize_concurrent_refinement();
1714   if (ecode != JNI_OK) {
1715     return ecode;
1716   }
1717 
1718   ecode = initialize_young_gen_sampling_thread();
1719   if (ecode != JNI_OK) {
1720     return ecode;
1721   }
1722 
1723   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1724                                                 DirtyCardQ_FL_lock,
1725                                                 (int)concurrent_refine()->yellow_zone(),
1726                                                 (int)concurrent_refine()->red_zone(),
1727                                                 Shared_DirtyCardQ_lock,
1728                                                 NULL,  // fl_owner
1729                                                 true); // init_free_ids
1730 
1731   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1732                                     DirtyCardQ_FL_lock,
1733                                     -1, // never trigger processing
1734                                     -1, // no limit on length
1735                                     Shared_DirtyCardQ_lock,
1736                                     &JavaThread::dirty_card_queue_set());
1737 
1738   // Here we allocate the dummy HeapRegion that is required by the
1739   // G1AllocRegion class.
1740   HeapRegion* dummy_region = _hrm.get_dummy_region();
1741 
1742   // We'll re-use the same region whether the alloc region will
1743   // require BOT updates or not and, if it doesn't, then a non-young
1744   // region will complain that it cannot support allocations without
1745   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1746   dummy_region->set_eden();
1747   // Make sure it's full.
1748   dummy_region->set_top(dummy_region->end());
1749   G1AllocRegion::setup(this, dummy_region);
1750 
1751   _allocator->init_mutator_alloc_region();
1752 
1753   // Do create of the monitoring and management support so that
1754   // values in the heap have been properly initialized.
1755   _g1mm = new G1MonitoringSupport(this);
1756 
1757   G1StringDedup::initialize();
1758 
1759   _preserved_marks_set.init(ParallelGCThreads);
1760 
1761   _collection_set.initialize(max_regions());
1762 
1763   return JNI_OK;
1764 }
1765 
1766 void G1CollectedHeap::initialize_serviceability() {
1767   _eden_pool = new G1EdenPool(this);
1768   _survivor_pool = new G1SurvivorPool(this);
1769   _old_pool = new G1OldGenPool(this);
1770 
1771   _full_gc_memory_manager.add_pool(_eden_pool);
1772   _full_gc_memory_manager.add_pool(_survivor_pool);
1773   _full_gc_memory_manager.add_pool(_old_pool);
1774 
1775   _memory_manager.add_pool(_eden_pool);
1776   _memory_manager.add_pool(_survivor_pool);
1777 
1778 }
1779 
1780 void G1CollectedHeap::stop() {
1781   // Stop all concurrent threads. We do this to make sure these threads
1782   // do not continue to execute and access resources (e.g. logging)
1783   // that are destroyed during shutdown.
1784   _cr->stop();
1785   _young_gen_sampling_thread->stop();
1786   _cmThread->stop();
1787   if (G1StringDedup::is_enabled()) {
1788     G1StringDedup::stop();
1789   }
1790 }
1791 
1792 void G1CollectedHeap::safepoint_synchronize_begin() {
1793   SuspendibleThreadSet::synchronize();
1794 }
1795 
1796 void G1CollectedHeap::safepoint_synchronize_end() {
1797   SuspendibleThreadSet::desynchronize();
1798 }
1799 
1800 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1801   return HeapRegion::max_region_size();
1802 }
1803 
1804 void G1CollectedHeap::post_initialize() {
1805   CollectedHeap::post_initialize();
1806   ref_processing_init();
1807 }
1808 
1809 void G1CollectedHeap::ref_processing_init() {
1810   // Reference processing in G1 currently works as follows:
1811   //
1812   // * There are two reference processor instances. One is
1813   //   used to record and process discovered references
1814   //   during concurrent marking; the other is used to
1815   //   record and process references during STW pauses
1816   //   (both full and incremental).
1817   // * Both ref processors need to 'span' the entire heap as
1818   //   the regions in the collection set may be dotted around.
1819   //
1820   // * For the concurrent marking ref processor:
1821   //   * Reference discovery is enabled at initial marking.
1822   //   * Reference discovery is disabled and the discovered
1823   //     references processed etc during remarking.
1824   //   * Reference discovery is MT (see below).
1825   //   * Reference discovery requires a barrier (see below).
1826   //   * Reference processing may or may not be MT
1827   //     (depending on the value of ParallelRefProcEnabled
1828   //     and ParallelGCThreads).
1829   //   * A full GC disables reference discovery by the CM
1830   //     ref processor and abandons any entries on it's
1831   //     discovered lists.
1832   //
1833   // * For the STW processor:
1834   //   * Non MT discovery is enabled at the start of a full GC.
1835   //   * Processing and enqueueing during a full GC is non-MT.
1836   //   * During a full GC, references are processed after marking.
1837   //
1838   //   * Discovery (may or may not be MT) is enabled at the start
1839   //     of an incremental evacuation pause.
1840   //   * References are processed near the end of a STW evacuation pause.
1841   //   * For both types of GC:
1842   //     * Discovery is atomic - i.e. not concurrent.
1843   //     * Reference discovery will not need a barrier.
1844 
1845   MemRegion mr = reserved_region();
1846 
1847   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1848 
1849   // Concurrent Mark ref processor
1850   _ref_processor_cm =
1851     new ReferenceProcessor(mr,    // span
1852                            mt_processing,
1853                                 // mt processing
1854                            ParallelGCThreads,
1855                                 // degree of mt processing
1856                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1857                                 // mt discovery
1858                            MAX2(ParallelGCThreads, ConcGCThreads),
1859                                 // degree of mt discovery
1860                            false,
1861                                 // Reference discovery is not atomic
1862                            &_is_alive_closure_cm);
1863                                 // is alive closure
1864                                 // (for efficiency/performance)
1865 
1866   // STW ref processor
1867   _ref_processor_stw =
1868     new ReferenceProcessor(mr,    // span
1869                            mt_processing,
1870                                 // mt processing
1871                            ParallelGCThreads,
1872                                 // degree of mt processing
1873                            (ParallelGCThreads > 1),
1874                                 // mt discovery
1875                            ParallelGCThreads,
1876                                 // degree of mt discovery
1877                            true,
1878                                 // Reference discovery is atomic
1879                            &_is_alive_closure_stw);
1880                                 // is alive closure
1881                                 // (for efficiency/performance)
1882 }
1883 
1884 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1885   return _collector_policy;
1886 }
1887 
1888 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1889   return &_soft_ref_policy;
1890 }
1891 
1892 size_t G1CollectedHeap::capacity() const {
1893   return _hrm.length() * HeapRegion::GrainBytes;
1894 }
1895 
1896 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1897   return _hrm.total_free_bytes();
1898 }
1899 
1900 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1901   hr->reset_gc_time_stamp();
1902 }
1903 
1904 #ifndef PRODUCT
1905 
1906 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1907 private:
1908   unsigned _gc_time_stamp;
1909   bool _failures;
1910 
1911 public:
1912   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1913     _gc_time_stamp(gc_time_stamp), _failures(false) { }
1914 
1915   virtual bool do_heap_region(HeapRegion* hr) {
1916     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1917     if (_gc_time_stamp != region_gc_time_stamp) {
1918       log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1919                             region_gc_time_stamp, _gc_time_stamp);
1920       _failures = true;
1921     }
1922     return false;
1923   }
1924 
1925   bool failures() { return _failures; }
1926 };
1927 
1928 void G1CollectedHeap::check_gc_time_stamps() {
1929   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1930   heap_region_iterate(&cl);
1931   guarantee(!cl.failures(), "all GC time stamps should have been reset");
1932 }
1933 #endif // PRODUCT
1934 
1935 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1936   _hot_card_cache->drain(cl, worker_i);
1937 }
1938 
1939 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1940   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1941   size_t n_completed_buffers = 0;
1942   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1943     n_completed_buffers++;
1944   }
1945   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1946   dcqs.clear_n_completed_buffers();
1947   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1948 }
1949 
1950 // Computes the sum of the storage used by the various regions.
1951 size_t G1CollectedHeap::used() const {
1952   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1953   if (_archive_allocator != NULL) {
1954     result += _archive_allocator->used();
1955   }
1956   return result;
1957 }
1958 
1959 size_t G1CollectedHeap::used_unlocked() const {
1960   return _summary_bytes_used;
1961 }
1962 
1963 class SumUsedClosure: public HeapRegionClosure {
1964   size_t _used;
1965 public:
1966   SumUsedClosure() : _used(0) {}
1967   bool do_heap_region(HeapRegion* r) {
1968     _used += r->used();
1969     return false;
1970   }
1971   size_t result() { return _used; }
1972 };
1973 
1974 size_t G1CollectedHeap::recalculate_used() const {
1975   double recalculate_used_start = os::elapsedTime();
1976 
1977   SumUsedClosure blk;
1978   heap_region_iterate(&blk);
1979 
1980   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1981   return blk.result();
1982 }
1983 
1984 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1985   switch (cause) {
1986     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1987     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1988     case GCCause::_wb_conc_mark:                        return true;
1989     default :                                           return false;
1990   }
1991 }
1992 
1993 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1994   switch (cause) {
1995     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
1996     case GCCause::_g1_humongous_allocation: return true;
1997     default:                                return is_user_requested_concurrent_full_gc(cause);
1998   }
1999 }
2000 
2001 #ifndef PRODUCT
2002 void G1CollectedHeap::allocate_dummy_regions() {
2003   // Let's fill up most of the region
2004   size_t word_size = HeapRegion::GrainWords - 1024;
2005   // And as a result the region we'll allocate will be humongous.
2006   guarantee(is_humongous(word_size), "sanity");
2007 
2008   // _filler_array_max_size is set to humongous object threshold
2009   // but temporarily change it to use CollectedHeap::fill_with_object().
2010   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2011 
2012   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2013     // Let's use the existing mechanism for the allocation
2014     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2015     if (dummy_obj != NULL) {
2016       MemRegion mr(dummy_obj, word_size);
2017       CollectedHeap::fill_with_object(mr);
2018     } else {
2019       // If we can't allocate once, we probably cannot allocate
2020       // again. Let's get out of the loop.
2021       break;
2022     }
2023   }
2024 }
2025 #endif // !PRODUCT
2026 
2027 void G1CollectedHeap::increment_old_marking_cycles_started() {
2028   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2029          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2030          "Wrong marking cycle count (started: %d, completed: %d)",
2031          _old_marking_cycles_started, _old_marking_cycles_completed);
2032 
2033   _old_marking_cycles_started++;
2034 }
2035 
2036 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2037   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2038 
2039   // We assume that if concurrent == true, then the caller is a
2040   // concurrent thread that was joined the Suspendible Thread
2041   // Set. If there's ever a cheap way to check this, we should add an
2042   // assert here.
2043 
2044   // Given that this method is called at the end of a Full GC or of a
2045   // concurrent cycle, and those can be nested (i.e., a Full GC can
2046   // interrupt a concurrent cycle), the number of full collections
2047   // completed should be either one (in the case where there was no
2048   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2049   // behind the number of full collections started.
2050 
2051   // This is the case for the inner caller, i.e. a Full GC.
2052   assert(concurrent ||
2053          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2054          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2055          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2056          "is inconsistent with _old_marking_cycles_completed = %u",
2057          _old_marking_cycles_started, _old_marking_cycles_completed);
2058 
2059   // This is the case for the outer caller, i.e. the concurrent cycle.
2060   assert(!concurrent ||
2061          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2062          "for outer caller (concurrent cycle): "
2063          "_old_marking_cycles_started = %u "
2064          "is inconsistent with _old_marking_cycles_completed = %u",
2065          _old_marking_cycles_started, _old_marking_cycles_completed);
2066 
2067   _old_marking_cycles_completed += 1;
2068 
2069   // We need to clear the "in_progress" flag in the CM thread before
2070   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2071   // is set) so that if a waiter requests another System.gc() it doesn't
2072   // incorrectly see that a marking cycle is still in progress.
2073   if (concurrent) {
2074     _cmThread->set_idle();
2075   }
2076 
2077   // This notify_all() will ensure that a thread that called
2078   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2079   // and it's waiting for a full GC to finish will be woken up. It is
2080   // waiting in VM_G1CollectForAllocation::doit_epilogue().
2081   FullGCCount_lock->notify_all();
2082 }
2083 
2084 void G1CollectedHeap::collect(GCCause::Cause cause) {
2085   assert_heap_not_locked();
2086 
2087   uint gc_count_before;
2088   uint old_marking_count_before;
2089   uint full_gc_count_before;
2090   bool retry_gc;
2091 
2092   do {
2093     retry_gc = false;
2094 
2095     {
2096       MutexLocker ml(Heap_lock);
2097 
2098       // Read the GC count while holding the Heap_lock
2099       gc_count_before = total_collections();
2100       full_gc_count_before = total_full_collections();
2101       old_marking_count_before = _old_marking_cycles_started;
2102     }
2103 
2104     if (should_do_concurrent_full_gc(cause)) {
2105       // Schedule an initial-mark evacuation pause that will start a
2106       // concurrent cycle. We're setting word_size to 0 which means that
2107       // we are not requesting a post-GC allocation.
2108       VM_G1CollectForAllocation op(0,     /* word_size */
2109                                    gc_count_before,
2110                                    cause,
2111                                    true,  /* should_initiate_conc_mark */
2112                                    g1_policy()->max_pause_time_ms());
2113       VMThread::execute(&op);
2114       if (!op.pause_succeeded()) {
2115         if (old_marking_count_before == _old_marking_cycles_started) {
2116           retry_gc = op.should_retry_gc();
2117         } else {
2118           // A Full GC happened while we were trying to schedule the
2119           // initial-mark GC. No point in starting a new cycle given
2120           // that the whole heap was collected anyway.
2121         }
2122 
2123         if (retry_gc) {
2124           if (GCLocker::is_active_and_needs_gc()) {
2125             GCLocker::stall_until_clear();
2126           }
2127         }
2128       }
2129     } else {
2130       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2131           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2132 
2133         // Schedule a standard evacuation pause. We're setting word_size
2134         // to 0 which means that we are not requesting a post-GC allocation.
2135         VM_G1CollectForAllocation op(0,     /* word_size */
2136                                      gc_count_before,
2137                                      cause,
2138                                      false, /* should_initiate_conc_mark */
2139                                      g1_policy()->max_pause_time_ms());
2140         VMThread::execute(&op);
2141       } else {
2142         // Schedule a Full GC.
2143         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2144         VMThread::execute(&op);
2145       }
2146     }
2147   } while (retry_gc);
2148 }
2149 
2150 bool G1CollectedHeap::is_in(const void* p) const {
2151   if (_hrm.reserved().contains(p)) {
2152     // Given that we know that p is in the reserved space,
2153     // heap_region_containing() should successfully
2154     // return the containing region.
2155     HeapRegion* hr = heap_region_containing(p);
2156     return hr->is_in(p);
2157   } else {
2158     return false;
2159   }
2160 }
2161 
2162 #ifdef ASSERT
2163 bool G1CollectedHeap::is_in_exact(const void* p) const {
2164   bool contains = reserved_region().contains(p);
2165   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2166   if (contains && available) {
2167     return true;
2168   } else {
2169     return false;
2170   }
2171 }
2172 #endif
2173 
2174 // Iteration functions.
2175 
2176 // Iterates an ObjectClosure over all objects within a HeapRegion.
2177 
2178 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2179   ObjectClosure* _cl;
2180 public:
2181   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2182   bool do_heap_region(HeapRegion* r) {
2183     if (!r->is_continues_humongous()) {
2184       r->object_iterate(_cl);
2185     }
2186     return false;
2187   }
2188 };
2189 
2190 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2191   IterateObjectClosureRegionClosure blk(cl);
2192   heap_region_iterate(&blk);
2193 }
2194 
2195 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2196   _hrm.iterate(cl);
2197 }
2198 
2199 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2200                                                                  HeapRegionClaimer *hrclaimer,
2201                                                                  uint worker_id) const {
2202   _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2203 }
2204 
2205 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2206                                                          HeapRegionClaimer *hrclaimer) const {
2207   _hrm.par_iterate(cl, hrclaimer, 0);
2208 }
2209 
2210 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2211   _collection_set.iterate(cl);
2212 }
2213 
2214 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2215   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2216 }
2217 
2218 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2219   HeapRegion* hr = heap_region_containing(addr);
2220   return hr->block_start(addr);
2221 }
2222 
2223 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2224   HeapRegion* hr = heap_region_containing(addr);
2225   return hr->block_size(addr);
2226 }
2227 
2228 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2229   HeapRegion* hr = heap_region_containing(addr);
2230   return hr->block_is_obj(addr);
2231 }
2232 
2233 bool G1CollectedHeap::supports_tlab_allocation() const {
2234   return true;
2235 }
2236 
2237 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2238   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2239 }
2240 
2241 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2242   return _eden.length() * HeapRegion::GrainBytes;
2243 }
2244 
2245 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2246 // must be equal to the humongous object limit.
2247 size_t G1CollectedHeap::max_tlab_size() const {
2248   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2249 }
2250 
2251 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2252   return _allocator->unsafe_max_tlab_alloc();
2253 }
2254 
2255 size_t G1CollectedHeap::max_capacity() const {
2256   return _hrm.reserved().byte_size();
2257 }
2258 
2259 jlong G1CollectedHeap::millis_since_last_gc() {
2260   // See the notes in GenCollectedHeap::millis_since_last_gc()
2261   // for more information about the implementation.
2262   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2263     _g1_policy->collection_pause_end_millis();
2264   if (ret_val < 0) {
2265     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2266       ". returning zero instead.", ret_val);
2267     return 0;
2268   }
2269   return ret_val;
2270 }
2271 
2272 void G1CollectedHeap::prepare_for_verify() {
2273   _verifier->prepare_for_verify();
2274 }
2275 
2276 void G1CollectedHeap::verify(VerifyOption vo) {
2277   _verifier->verify(vo);
2278 }
2279 
2280 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2281   return true;
2282 }
2283 
2284 const char* const* G1CollectedHeap::concurrent_phases() const {
2285   return _cmThread->concurrent_phases();
2286 }
2287 
2288 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2289   return _cmThread->request_concurrent_phase(phase);
2290 }
2291 
2292 class PrintRegionClosure: public HeapRegionClosure {
2293   outputStream* _st;
2294 public:
2295   PrintRegionClosure(outputStream* st) : _st(st) {}
2296   bool do_heap_region(HeapRegion* r) {
2297     r->print_on(_st);
2298     return false;
2299   }
2300 };
2301 
2302 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2303                                        const HeapRegion* hr,
2304                                        const VerifyOption vo) const {
2305   switch (vo) {
2306   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2307   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2308   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2309   default:                            ShouldNotReachHere();
2310   }
2311   return false; // keep some compilers happy
2312 }
2313 
2314 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2315                                        const VerifyOption vo) const {
2316   switch (vo) {
2317   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2318   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2319   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2320   default:                            ShouldNotReachHere();
2321   }
2322   return false; // keep some compilers happy
2323 }
2324 
2325 void G1CollectedHeap::print_heap_regions() const {
2326   LogTarget(Trace, gc, heap, region) lt;
2327   if (lt.is_enabled()) {
2328     LogStream ls(lt);
2329     print_regions_on(&ls);
2330   }
2331 }
2332 
2333 void G1CollectedHeap::print_on(outputStream* st) const {
2334   st->print(" %-20s", "garbage-first heap");
2335   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2336             capacity()/K, used_unlocked()/K);
2337   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2338             p2i(_hrm.reserved().start()),
2339             p2i(_hrm.reserved().end()));
2340   st->cr();
2341   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2342   uint young_regions = young_regions_count();
2343   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2344             (size_t) young_regions * HeapRegion::GrainBytes / K);
2345   uint survivor_regions = survivor_regions_count();
2346   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2347             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2348   st->cr();
2349   MetaspaceAux::print_on(st);
2350 }
2351 
2352 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2353   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2354                "HS=humongous(starts), HC=humongous(continues), "
2355                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2356                "TAMS=top-at-mark-start (previous, next)");
2357   PrintRegionClosure blk(st);
2358   heap_region_iterate(&blk);
2359 }
2360 
2361 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2362   print_on(st);
2363 
2364   // Print the per-region information.
2365   print_regions_on(st);
2366 }
2367 
2368 void G1CollectedHeap::print_on_error(outputStream* st) const {
2369   this->CollectedHeap::print_on_error(st);
2370 
2371   if (_cm != NULL) {
2372     st->cr();
2373     _cm->print_on_error(st);
2374   }
2375 }
2376 
2377 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2378   workers()->print_worker_threads_on(st);
2379   _cmThread->print_on(st);
2380   st->cr();
2381   _cm->print_worker_threads_on(st);
2382   _cr->print_threads_on(st);
2383   _young_gen_sampling_thread->print_on(st);
2384   if (G1StringDedup::is_enabled()) {
2385     G1StringDedup::print_worker_threads_on(st);
2386   }
2387 }
2388 
2389 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2390   workers()->threads_do(tc);
2391   tc->do_thread(_cmThread);
2392   _cm->threads_do(tc);
2393   _cr->threads_do(tc);
2394   tc->do_thread(_young_gen_sampling_thread);
2395   if (G1StringDedup::is_enabled()) {
2396     G1StringDedup::threads_do(tc);
2397   }
2398 }
2399 
2400 void G1CollectedHeap::print_tracing_info() const {
2401   g1_rem_set()->print_summary_info();
2402   concurrent_mark()->print_summary_info();
2403 }
2404 
2405 #ifndef PRODUCT
2406 // Helpful for debugging RSet issues.
2407 
2408 class PrintRSetsClosure : public HeapRegionClosure {
2409 private:
2410   const char* _msg;
2411   size_t _occupied_sum;
2412 
2413 public:
2414   bool do_heap_region(HeapRegion* r) {
2415     HeapRegionRemSet* hrrs = r->rem_set();
2416     size_t occupied = hrrs->occupied();
2417     _occupied_sum += occupied;
2418 
2419     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2420     if (occupied == 0) {
2421       tty->print_cr("  RSet is empty");
2422     } else {
2423       hrrs->print();
2424     }
2425     tty->print_cr("----------");
2426     return false;
2427   }
2428 
2429   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2430     tty->cr();
2431     tty->print_cr("========================================");
2432     tty->print_cr("%s", msg);
2433     tty->cr();
2434   }
2435 
2436   ~PrintRSetsClosure() {
2437     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2438     tty->print_cr("========================================");
2439     tty->cr();
2440   }
2441 };
2442 
2443 void G1CollectedHeap::print_cset_rsets() {
2444   PrintRSetsClosure cl("Printing CSet RSets");
2445   collection_set_iterate(&cl);
2446 }
2447 
2448 void G1CollectedHeap::print_all_rsets() {
2449   PrintRSetsClosure cl("Printing All RSets");;
2450   heap_region_iterate(&cl);
2451 }
2452 #endif // PRODUCT
2453 
2454 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2455 
2456   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2457   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2458   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2459 
2460   size_t eden_capacity_bytes =
2461     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2462 
2463   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2464   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2465                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2466 }
2467 
2468 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2469   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2470                        stats->unused(), stats->used(), stats->region_end_waste(),
2471                        stats->regions_filled(), stats->direct_allocated(),
2472                        stats->failure_used(), stats->failure_waste());
2473 }
2474 
2475 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2476   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2477   gc_tracer->report_gc_heap_summary(when, heap_summary);
2478 
2479   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2480   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2481 }
2482 
2483 G1CollectedHeap* G1CollectedHeap::heap() {
2484   CollectedHeap* heap = Universe::heap();
2485   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2486   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2487   return (G1CollectedHeap*)heap;
2488 }
2489 
2490 void G1CollectedHeap::gc_prologue(bool full) {
2491   // always_do_update_barrier = false;
2492   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2493 
2494   // This summary needs to be printed before incrementing total collections.
2495   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2496 
2497   // Update common counters.
2498   increment_total_collections(full /* full gc */);
2499   if (full) {
2500     increment_old_marking_cycles_started();
2501     reset_gc_time_stamp();
2502   } else {
2503     increment_gc_time_stamp();
2504   }
2505 
2506   // Fill TLAB's and such
2507   double start = os::elapsedTime();
2508   accumulate_statistics_all_tlabs();
2509   ensure_parsability(true);
2510   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2511 }
2512 
2513 void G1CollectedHeap::gc_epilogue(bool full) {
2514   // Update common counters.
2515   if (full) {
2516     // Update the number of full collections that have been completed.
2517     increment_old_marking_cycles_completed(false /* concurrent */);
2518   }
2519 
2520   // We are at the end of the GC. Total collections has already been increased.
2521   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2522 
2523   // FIXME: what is this about?
2524   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2525   // is set.
2526 #if COMPILER2_OR_JVMCI
2527   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2528 #endif
2529   // always_do_update_barrier = true;
2530 
2531   double start = os::elapsedTime();
2532   resize_all_tlabs();
2533   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2534 
2535   MemoryService::track_memory_usage();
2536   // We have just completed a GC. Update the soft reference
2537   // policy with the new heap occupancy
2538   Universe::update_heap_info_at_gc();
2539 }
2540 
2541 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2542                                                uint gc_count_before,
2543                                                bool* succeeded,
2544                                                GCCause::Cause gc_cause) {
2545   assert_heap_not_locked_and_not_at_safepoint();
2546   VM_G1CollectForAllocation op(word_size,
2547                                gc_count_before,
2548                                gc_cause,
2549                                false, /* should_initiate_conc_mark */
2550                                g1_policy()->max_pause_time_ms());
2551   VMThread::execute(&op);
2552 
2553   HeapWord* result = op.result();
2554   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2555   assert(result == NULL || ret_succeeded,
2556          "the result should be NULL if the VM did not succeed");
2557   *succeeded = ret_succeeded;
2558 
2559   assert_heap_not_locked();
2560   return result;
2561 }
2562 
2563 void
2564 G1CollectedHeap::doConcurrentMark() {
2565   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2566   if (!_cmThread->in_progress()) {
2567     _cmThread->set_started();
2568     CGC_lock->notify();
2569   }
2570 }
2571 
2572 size_t G1CollectedHeap::pending_card_num() {
2573   size_t extra_cards = 0;
2574   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2575     DirtyCardQueue& dcq = curr->dirty_card_queue();
2576     extra_cards += dcq.size();
2577   }
2578   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2579   size_t buffer_size = dcqs.buffer_size();
2580   size_t buffer_num = dcqs.completed_buffers_num();
2581 
2582   return buffer_size * buffer_num + extra_cards;
2583 }
2584 
2585 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2586   // We don't nominate objects with many remembered set entries, on
2587   // the assumption that such objects are likely still live.
2588   HeapRegionRemSet* rem_set = r->rem_set();
2589 
2590   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2591          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2592          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2593 }
2594 
2595 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2596  private:
2597   size_t _total_humongous;
2598   size_t _candidate_humongous;
2599 
2600   DirtyCardQueue _dcq;
2601 
2602   bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2603     assert(region->is_starts_humongous(), "Must start a humongous object");
2604 
2605     oop obj = oop(region->bottom());
2606 
2607     // Dead objects cannot be eager reclaim candidates. Due to class
2608     // unloading it is unsafe to query their classes so we return early.
2609     if (g1h->is_obj_dead(obj, region)) {
2610       return false;
2611     }
2612 
2613     // Candidate selection must satisfy the following constraints
2614     // while concurrent marking is in progress:
2615     //
2616     // * In order to maintain SATB invariants, an object must not be
2617     // reclaimed if it was allocated before the start of marking and
2618     // has not had its references scanned.  Such an object must have
2619     // its references (including type metadata) scanned to ensure no
2620     // live objects are missed by the marking process.  Objects
2621     // allocated after the start of concurrent marking don't need to
2622     // be scanned.
2623     //
2624     // * An object must not be reclaimed if it is on the concurrent
2625     // mark stack.  Objects allocated after the start of concurrent
2626     // marking are never pushed on the mark stack.
2627     //
2628     // Nominating only objects allocated after the start of concurrent
2629     // marking is sufficient to meet both constraints.  This may miss
2630     // some objects that satisfy the constraints, but the marking data
2631     // structures don't support efficiently performing the needed
2632     // additional tests or scrubbing of the mark stack.
2633     //
2634     // However, we presently only nominate is_typeArray() objects.
2635     // A humongous object containing references induces remembered
2636     // set entries on other regions.  In order to reclaim such an
2637     // object, those remembered sets would need to be cleaned up.
2638     //
2639     // We also treat is_typeArray() objects specially, allowing them
2640     // to be reclaimed even if allocated before the start of
2641     // concurrent mark.  For this we rely on mark stack insertion to
2642     // exclude is_typeArray() objects, preventing reclaiming an object
2643     // that is in the mark stack.  We also rely on the metadata for
2644     // such objects to be built-in and so ensured to be kept live.
2645     // Frequent allocation and drop of large binary blobs is an
2646     // important use case for eager reclaim, and this special handling
2647     // may reduce needed headroom.
2648 
2649     return obj->is_typeArray() &&
2650            g1h->is_potential_eager_reclaim_candidate(region);
2651   }
2652 
2653  public:
2654   RegisterHumongousWithInCSetFastTestClosure()
2655   : _total_humongous(0),
2656     _candidate_humongous(0),
2657     _dcq(&JavaThread::dirty_card_queue_set()) {
2658   }
2659 
2660   virtual bool do_heap_region(HeapRegion* r) {
2661     if (!r->is_starts_humongous()) {
2662       return false;
2663     }
2664     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2665 
2666     bool is_candidate = humongous_region_is_candidate(g1h, r);
2667     uint rindex = r->hrm_index();
2668     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2669     if (is_candidate) {
2670       _candidate_humongous++;
2671       g1h->register_humongous_region_with_cset(rindex);
2672       // Is_candidate already filters out humongous object with large remembered sets.
2673       // If we have a humongous object with a few remembered sets, we simply flush these
2674       // remembered set entries into the DCQS. That will result in automatic
2675       // re-evaluation of their remembered set entries during the following evacuation
2676       // phase.
2677       if (!r->rem_set()->is_empty()) {
2678         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2679                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2680         G1CardTable* ct = g1h->card_table();
2681         HeapRegionRemSetIterator hrrs(r->rem_set());
2682         size_t card_index;
2683         while (hrrs.has_next(card_index)) {
2684           jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2685           // The remembered set might contain references to already freed
2686           // regions. Filter out such entries to avoid failing card table
2687           // verification.
2688           if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2689             if (*card_ptr != G1CardTable::dirty_card_val()) {
2690               *card_ptr = G1CardTable::dirty_card_val();
2691               _dcq.enqueue(card_ptr);
2692             }
2693           }
2694         }
2695         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2696                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2697                hrrs.n_yielded(), r->rem_set()->occupied());
2698         r->rem_set()->clear_locked();
2699       }
2700       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2701     }
2702     _total_humongous++;
2703 
2704     return false;
2705   }
2706 
2707   size_t total_humongous() const { return _total_humongous; }
2708   size_t candidate_humongous() const { return _candidate_humongous; }
2709 
2710   void flush_rem_set_entries() { _dcq.flush(); }
2711 };
2712 
2713 void G1CollectedHeap::register_humongous_regions_with_cset() {
2714   if (!G1EagerReclaimHumongousObjects) {
2715     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2716     return;
2717   }
2718   double time = os::elapsed_counter();
2719 
2720   // Collect reclaim candidate information and register candidates with cset.
2721   RegisterHumongousWithInCSetFastTestClosure cl;
2722   heap_region_iterate(&cl);
2723 
2724   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2725   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2726                                                                   cl.total_humongous(),
2727                                                                   cl.candidate_humongous());
2728   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2729 
2730   // Finally flush all remembered set entries to re-check into the global DCQS.
2731   cl.flush_rem_set_entries();
2732 }
2733 
2734 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2735   public:
2736     bool do_heap_region(HeapRegion* hr) {
2737       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2738         hr->verify_rem_set();
2739       }
2740       return false;
2741     }
2742 };
2743 
2744 uint G1CollectedHeap::num_task_queues() const {
2745   return _task_queues->size();
2746 }
2747 
2748 #if TASKQUEUE_STATS
2749 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2750   st->print_raw_cr("GC Task Stats");
2751   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2752   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2753 }
2754 
2755 void G1CollectedHeap::print_taskqueue_stats() const {
2756   if (!log_is_enabled(Trace, gc, task, stats)) {
2757     return;
2758   }
2759   Log(gc, task, stats) log;
2760   ResourceMark rm;
2761   LogStream ls(log.trace());
2762   outputStream* st = &ls;
2763 
2764   print_taskqueue_stats_hdr(st);
2765 
2766   TaskQueueStats totals;
2767   const uint n = num_task_queues();
2768   for (uint i = 0; i < n; ++i) {
2769     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2770     totals += task_queue(i)->stats;
2771   }
2772   st->print_raw("tot "); totals.print(st); st->cr();
2773 
2774   DEBUG_ONLY(totals.verify());
2775 }
2776 
2777 void G1CollectedHeap::reset_taskqueue_stats() {
2778   const uint n = num_task_queues();
2779   for (uint i = 0; i < n; ++i) {
2780     task_queue(i)->stats.reset();
2781   }
2782 }
2783 #endif // TASKQUEUE_STATS
2784 
2785 void G1CollectedHeap::wait_for_root_region_scanning() {
2786   double scan_wait_start = os::elapsedTime();
2787   // We have to wait until the CM threads finish scanning the
2788   // root regions as it's the only way to ensure that all the
2789   // objects on them have been correctly scanned before we start
2790   // moving them during the GC.
2791   bool waited = _cm->root_regions()->wait_until_scan_finished();
2792   double wait_time_ms = 0.0;
2793   if (waited) {
2794     double scan_wait_end = os::elapsedTime();
2795     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2796   }
2797   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2798 }
2799 
2800 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2801 private:
2802   G1HRPrinter* _hr_printer;
2803 public:
2804   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2805 
2806   virtual bool do_heap_region(HeapRegion* r) {
2807     _hr_printer->cset(r);
2808     return false;
2809   }
2810 };
2811 
2812 void G1CollectedHeap::start_new_collection_set() {
2813   collection_set()->start_incremental_building();
2814 
2815   clear_cset_fast_test();
2816 
2817   guarantee(_eden.length() == 0, "eden should have been cleared");
2818   g1_policy()->transfer_survivors_to_cset(survivor());
2819 }
2820 
2821 bool
2822 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2823   assert_at_safepoint_on_vm_thread();
2824   guarantee(!is_gc_active(), "collection is not reentrant");
2825 
2826   if (GCLocker::check_active_before_gc()) {
2827     return false;
2828   }
2829 
2830   _gc_timer_stw->register_gc_start();
2831 
2832   GCIdMark gc_id_mark;
2833   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2834 
2835   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2836   ResourceMark rm;
2837 
2838   g1_policy()->note_gc_start();
2839 
2840   wait_for_root_region_scanning();
2841 
2842   print_heap_before_gc();
2843   print_heap_regions();
2844   trace_heap_before_gc(_gc_tracer_stw);
2845 
2846   _verifier->verify_region_sets_optional();
2847   _verifier->verify_dirty_young_regions();
2848 
2849   // We should not be doing initial mark unless the conc mark thread is running
2850   if (!_cmThread->should_terminate()) {
2851     // This call will decide whether this pause is an initial-mark
2852     // pause. If it is, during_initial_mark_pause() will return true
2853     // for the duration of this pause.
2854     g1_policy()->decide_on_conc_mark_initiation();
2855   }
2856 
2857   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2858   assert(!collector_state()->during_initial_mark_pause() ||
2859           collector_state()->gcs_are_young(), "sanity");
2860 
2861   // We also do not allow mixed GCs during marking.
2862   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2863 
2864   // Record whether this pause is an initial mark. When the current
2865   // thread has completed its logging output and it's safe to signal
2866   // the CM thread, the flag's value in the policy has been reset.
2867   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2868 
2869   // Inner scope for scope based logging, timers, and stats collection
2870   {
2871     EvacuationInfo evacuation_info;
2872 
2873     if (collector_state()->during_initial_mark_pause()) {
2874       // We are about to start a marking cycle, so we increment the
2875       // full collection counter.
2876       increment_old_marking_cycles_started();
2877       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2878     }
2879 
2880     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2881 
2882     GCTraceCPUTime tcpu;
2883 
2884     G1HeapVerifier::G1VerifyType verify_type;
2885     FormatBuffer<> gc_string("Pause ");
2886     if (collector_state()->during_initial_mark_pause()) {
2887       gc_string.append("Initial Mark");
2888       verify_type = G1HeapVerifier::G1VerifyInitialMark;
2889     } else if (collector_state()->gcs_are_young()) {
2890       gc_string.append("Young");
2891       verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2892     } else {
2893       gc_string.append("Mixed");
2894       verify_type = G1HeapVerifier::G1VerifyMixed;
2895     }
2896     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2897 
2898     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2899                                                                   workers()->active_workers(),
2900                                                                   Threads::number_of_non_daemon_threads());
2901     workers()->update_active_workers(active_workers);
2902     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2903 
2904     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2905     TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2906 
2907     // If the secondary_free_list is not empty, append it to the
2908     // free_list. No need to wait for the cleanup operation to finish;
2909     // the region allocation code will check the secondary_free_list
2910     // and wait if necessary. If the G1StressConcRegionFreeing flag is
2911     // set, skip this step so that the region allocation code has to
2912     // get entries from the secondary_free_list.
2913     if (!G1StressConcRegionFreeing) {
2914       append_secondary_free_list_if_not_empty_with_lock();
2915     }
2916 
2917     G1HeapTransition heap_transition(this);
2918     size_t heap_used_bytes_before_gc = used();
2919 
2920     // Don't dynamically change the number of GC threads this early.  A value of
2921     // 0 is used to indicate serial work.  When parallel work is done,
2922     // it will be set.
2923 
2924     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2925       IsGCActiveMark x;
2926 
2927       gc_prologue(false);
2928 
2929       if (VerifyRememberedSets) {
2930         log_info(gc, verify)("[Verifying RemSets before GC]");
2931         VerifyRegionRemSetClosure v_cl;
2932         heap_region_iterate(&v_cl);
2933       }
2934 
2935       _verifier->verify_before_gc(verify_type);
2936 
2937       _verifier->check_bitmaps("GC Start");
2938 
2939 #if COMPILER2_OR_JVMCI
2940       DerivedPointerTable::clear();
2941 #endif
2942 
2943       // Please see comment in g1CollectedHeap.hpp and
2944       // G1CollectedHeap::ref_processing_init() to see how
2945       // reference processing currently works in G1.
2946 
2947       // Enable discovery in the STW reference processor
2948       if (g1_policy()->should_process_references()) {
2949         ref_processor_stw()->enable_discovery();
2950       } else {
2951         ref_processor_stw()->disable_discovery();
2952       }
2953 
2954       {
2955         // We want to temporarily turn off discovery by the
2956         // CM ref processor, if necessary, and turn it back on
2957         // on again later if we do. Using a scoped
2958         // NoRefDiscovery object will do this.
2959         NoRefDiscovery no_cm_discovery(ref_processor_cm());
2960 
2961         // Forget the current alloc region (we might even choose it to be part
2962         // of the collection set!).
2963         _allocator->release_mutator_alloc_region();
2964 
2965         // This timing is only used by the ergonomics to handle our pause target.
2966         // It is unclear why this should not include the full pause. We will
2967         // investigate this in CR 7178365.
2968         //
2969         // Preserving the old comment here if that helps the investigation:
2970         //
2971         // The elapsed time induced by the start time below deliberately elides
2972         // the possible verification above.
2973         double sample_start_time_sec = os::elapsedTime();
2974 
2975         g1_policy()->record_collection_pause_start(sample_start_time_sec);
2976 
2977         if (collector_state()->during_initial_mark_pause()) {
2978           concurrent_mark()->checkpoint_roots_initial_pre();
2979         }
2980 
2981         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2982 
2983         evacuation_info.set_collectionset_regions(collection_set()->region_length());
2984 
2985         // Make sure the remembered sets are up to date. This needs to be
2986         // done before register_humongous_regions_with_cset(), because the
2987         // remembered sets are used there to choose eager reclaim candidates.
2988         // If the remembered sets are not up to date we might miss some
2989         // entries that need to be handled.
2990         g1_rem_set()->cleanupHRRS();
2991 
2992         register_humongous_regions_with_cset();
2993 
2994         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2995 
2996         // We call this after finalize_cset() to
2997         // ensure that the CSet has been finalized.
2998         _cm->verify_no_cset_oops();
2999 
3000         if (_hr_printer.is_active()) {
3001           G1PrintCollectionSetClosure cl(&_hr_printer);
3002           _collection_set.iterate(&cl);
3003         }
3004 
3005         // Initialize the GC alloc regions.
3006         _allocator->init_gc_alloc_regions(evacuation_info);
3007 
3008         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3009         pre_evacuate_collection_set();
3010 
3011         // Actually do the work...
3012         evacuate_collection_set(&per_thread_states);
3013 
3014         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3015 
3016         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3017         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3018 
3019         eagerly_reclaim_humongous_regions();
3020 
3021         record_obj_copy_mem_stats();
3022         _survivor_evac_stats.adjust_desired_plab_sz();
3023         _old_evac_stats.adjust_desired_plab_sz();
3024 
3025         double start = os::elapsedTime();
3026         start_new_collection_set();
3027         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3028 
3029         if (evacuation_failed()) {
3030           set_used(recalculate_used());
3031           if (_archive_allocator != NULL) {
3032             _archive_allocator->clear_used();
3033           }
3034           for (uint i = 0; i < ParallelGCThreads; i++) {
3035             if (_evacuation_failed_info_array[i].has_failed()) {
3036               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3037             }
3038           }
3039         } else {
3040           // The "used" of the the collection set have already been subtracted
3041           // when they were freed.  Add in the bytes evacuated.
3042           increase_used(g1_policy()->bytes_copied_during_gc());
3043         }
3044 
3045         if (collector_state()->during_initial_mark_pause()) {
3046           // We have to do this before we notify the CM threads that
3047           // they can start working to make sure that all the
3048           // appropriate initialization is done on the CM object.
3049           concurrent_mark()->checkpoint_roots_initial_post();
3050           collector_state()->set_mark_in_progress(true);
3051           // Note that we don't actually trigger the CM thread at
3052           // this point. We do that later when we're sure that
3053           // the current thread has completed its logging output.
3054         }
3055 
3056         allocate_dummy_regions();
3057 
3058         _allocator->init_mutator_alloc_region();
3059 
3060         {
3061           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3062           if (expand_bytes > 0) {
3063             size_t bytes_before = capacity();
3064             // No need for an ergo logging here,
3065             // expansion_amount() does this when it returns a value > 0.
3066             double expand_ms;
3067             if (!expand(expand_bytes, _workers, &expand_ms)) {
3068               // We failed to expand the heap. Cannot do anything about it.
3069             }
3070             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3071           }
3072         }
3073 
3074         // We redo the verification but now wrt to the new CSet which
3075         // has just got initialized after the previous CSet was freed.
3076         _cm->verify_no_cset_oops();
3077 
3078         // This timing is only used by the ergonomics to handle our pause target.
3079         // It is unclear why this should not include the full pause. We will
3080         // investigate this in CR 7178365.
3081         double sample_end_time_sec = os::elapsedTime();
3082         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3083         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3084         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3085 
3086         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3087         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3088 
3089         if (VerifyRememberedSets) {
3090           log_info(gc, verify)("[Verifying RemSets after GC]");
3091           VerifyRegionRemSetClosure v_cl;
3092           heap_region_iterate(&v_cl);
3093         }
3094 
3095         _verifier->verify_after_gc(verify_type);
3096         _verifier->check_bitmaps("GC End");
3097 
3098         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3099         ref_processor_stw()->verify_no_references_recorded();
3100 
3101         // CM reference discovery will be re-enabled if necessary.
3102       }
3103 
3104 #ifdef TRACESPINNING
3105       ParallelTaskTerminator::print_termination_counts();
3106 #endif
3107 
3108       gc_epilogue(false);
3109     }
3110 
3111     // Print the remainder of the GC log output.
3112     if (evacuation_failed()) {
3113       log_info(gc)("To-space exhausted");
3114     }
3115 
3116     g1_policy()->print_phases();
3117     heap_transition.print();
3118 
3119     // It is not yet to safe to tell the concurrent mark to
3120     // start as we have some optional output below. We don't want the
3121     // output from the concurrent mark thread interfering with this
3122     // logging output either.
3123 
3124     _hrm.verify_optional();
3125     _verifier->verify_region_sets_optional();
3126 
3127     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3128     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3129 
3130     print_heap_after_gc();
3131     print_heap_regions();
3132     trace_heap_after_gc(_gc_tracer_stw);
3133 
3134     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3135     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3136     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3137     // before any GC notifications are raised.
3138     g1mm()->update_sizes();
3139 
3140     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3141     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3142     _gc_timer_stw->register_gc_end();
3143     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3144   }
3145   // It should now be safe to tell the concurrent mark thread to start
3146   // without its logging output interfering with the logging output
3147   // that came from the pause.
3148 
3149   if (should_start_conc_mark) {
3150     // CAUTION: after the doConcurrentMark() call below,
3151     // the concurrent marking thread(s) could be running
3152     // concurrently with us. Make sure that anything after
3153     // this point does not assume that we are the only GC thread
3154     // running. Note: of course, the actual marking work will
3155     // not start until the safepoint itself is released in
3156     // SuspendibleThreadSet::desynchronize().
3157     doConcurrentMark();
3158   }
3159 
3160   return true;
3161 }
3162 
3163 void G1CollectedHeap::remove_self_forwarding_pointers() {
3164   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3165   workers()->run_task(&rsfp_task);
3166 }
3167 
3168 void G1CollectedHeap::restore_after_evac_failure() {
3169   double remove_self_forwards_start = os::elapsedTime();
3170 
3171   remove_self_forwarding_pointers();
3172   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3173   _preserved_marks_set.restore(&task_executor);
3174 
3175   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3176 }
3177 
3178 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3179   if (!_evacuation_failed) {
3180     _evacuation_failed = true;
3181   }
3182 
3183   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3184   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3185 }
3186 
3187 bool G1ParEvacuateFollowersClosure::offer_termination() {
3188   G1ParScanThreadState* const pss = par_scan_state();
3189   start_term_time();
3190   const bool res = terminator()->offer_termination();
3191   end_term_time();
3192   return res;
3193 }
3194 
3195 void G1ParEvacuateFollowersClosure::do_void() {
3196   G1ParScanThreadState* const pss = par_scan_state();
3197   pss->trim_queue();
3198   do {
3199     pss->steal_and_trim_queue(queues());
3200   } while (!offer_termination());
3201 }
3202 
3203 class G1ParTask : public AbstractGangTask {
3204 protected:
3205   G1CollectedHeap*         _g1h;
3206   G1ParScanThreadStateSet* _pss;
3207   RefToScanQueueSet*       _queues;
3208   G1RootProcessor*         _root_processor;
3209   ParallelTaskTerminator   _terminator;
3210   uint                     _n_workers;
3211 
3212 public:
3213   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3214     : AbstractGangTask("G1 collection"),
3215       _g1h(g1h),
3216       _pss(per_thread_states),
3217       _queues(task_queues),
3218       _root_processor(root_processor),
3219       _terminator(n_workers, _queues),
3220       _n_workers(n_workers)
3221   {}
3222 
3223   void work(uint worker_id) {
3224     if (worker_id >= _n_workers) return;  // no work needed this round
3225 
3226     double start_sec = os::elapsedTime();
3227     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3228 
3229     {
3230       ResourceMark rm;
3231       HandleMark   hm;
3232 
3233       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3234 
3235       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3236       pss->set_ref_processor(rp);
3237 
3238       double start_strong_roots_sec = os::elapsedTime();
3239 
3240       _root_processor->evacuate_roots(pss->closures(), worker_id);
3241 
3242       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3243       // treating the nmethods visited to act as roots for concurrent marking.
3244       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3245       // objects copied by the current evacuation.
3246       _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3247                                                       pss->closures()->weak_codeblobs(),
3248                                                       worker_id);
3249 
3250       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3251 
3252       double term_sec = 0.0;
3253       size_t evac_term_attempts = 0;
3254       {
3255         double start = os::elapsedTime();
3256         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3257         evac.do_void();
3258 
3259         evac_term_attempts = evac.term_attempts();
3260         term_sec = evac.term_time();
3261         double elapsed_sec = os::elapsedTime() - start;
3262         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3263         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3264         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3265       }
3266 
3267       assert(pss->queue_is_empty(), "should be empty");
3268 
3269       if (log_is_enabled(Debug, gc, task, stats)) {
3270         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3271         size_t lab_waste;
3272         size_t lab_undo_waste;
3273         pss->waste(lab_waste, lab_undo_waste);
3274         _g1h->print_termination_stats(worker_id,
3275                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3276                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3277                                       term_sec * 1000.0,                          /* evac term time */
3278                                       evac_term_attempts,                         /* evac term attempts */
3279                                       lab_waste,                                  /* alloc buffer waste */
3280                                       lab_undo_waste                              /* undo waste */
3281                                       );
3282       }
3283 
3284       // Close the inner scope so that the ResourceMark and HandleMark
3285       // destructors are executed here and are included as part of the
3286       // "GC Worker Time".
3287     }
3288     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3289   }
3290 };
3291 
3292 void G1CollectedHeap::print_termination_stats_hdr() {
3293   log_debug(gc, task, stats)("GC Termination Stats");
3294   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3295   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3296   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3297 }
3298 
3299 void G1CollectedHeap::print_termination_stats(uint worker_id,
3300                                               double elapsed_ms,
3301                                               double strong_roots_ms,
3302                                               double term_ms,
3303                                               size_t term_attempts,
3304                                               size_t alloc_buffer_waste,
3305                                               size_t undo_waste) const {
3306   log_debug(gc, task, stats)
3307               ("%3d %9.2f %9.2f %6.2f "
3308                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3309                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3310                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3311                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3312                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3313                alloc_buffer_waste * HeapWordSize / K,
3314                undo_waste * HeapWordSize / K);
3315 }
3316 
3317 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3318 private:
3319   BoolObjectClosure* _is_alive;
3320   G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3321 
3322   int _initial_string_table_size;
3323   int _initial_symbol_table_size;
3324 
3325   bool  _process_strings;
3326   int _strings_processed;
3327   int _strings_removed;
3328 
3329   bool  _process_symbols;
3330   int _symbols_processed;
3331   int _symbols_removed;
3332 
3333   bool _process_string_dedup;
3334 
3335 public:
3336   G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3337     AbstractGangTask("String/Symbol Unlinking"),
3338     _is_alive(is_alive),
3339     _dedup_closure(is_alive, NULL, false),
3340     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3341     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3342     _process_string_dedup(process_string_dedup) {
3343 
3344     _initial_string_table_size = StringTable::the_table()->table_size();
3345     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3346     if (process_strings) {
3347       StringTable::clear_parallel_claimed_index();
3348     }
3349     if (process_symbols) {
3350       SymbolTable::clear_parallel_claimed_index();
3351     }
3352   }
3353 
3354   ~G1StringAndSymbolCleaningTask() {
3355     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3356               "claim value %d after unlink less than initial string table size %d",
3357               StringTable::parallel_claimed_index(), _initial_string_table_size);
3358     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3359               "claim value %d after unlink less than initial symbol table size %d",
3360               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3361 
3362     log_info(gc, stringtable)(
3363         "Cleaned string and symbol table, "
3364         "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3365         "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3366         strings_processed(), strings_removed(),
3367         symbols_processed(), symbols_removed());
3368   }
3369 
3370   void work(uint worker_id) {
3371     int strings_processed = 0;
3372     int strings_removed = 0;
3373     int symbols_processed = 0;
3374     int symbols_removed = 0;
3375     if (_process_strings) {
3376       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3377       Atomic::add(strings_processed, &_strings_processed);
3378       Atomic::add(strings_removed, &_strings_removed);
3379     }
3380     if (_process_symbols) {
3381       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3382       Atomic::add(symbols_processed, &_symbols_processed);
3383       Atomic::add(symbols_removed, &_symbols_removed);
3384     }
3385     if (_process_string_dedup) {
3386       G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3387     }
3388   }
3389 
3390   size_t strings_processed() const { return (size_t)_strings_processed; }
3391   size_t strings_removed()   const { return (size_t)_strings_removed; }
3392 
3393   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3394   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3395 };
3396 
3397 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3398 private:
3399   static Monitor* _lock;
3400 
3401   BoolObjectClosure* const _is_alive;
3402   const bool               _unloading_occurred;
3403   const uint               _num_workers;
3404 
3405   // Variables used to claim nmethods.
3406   CompiledMethod* _first_nmethod;
3407   CompiledMethod* volatile _claimed_nmethod;
3408 
3409   // The list of nmethods that need to be processed by the second pass.
3410   CompiledMethod* volatile _postponed_list;
3411   volatile uint            _num_entered_barrier;
3412 
3413  public:
3414   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3415       _is_alive(is_alive),
3416       _unloading_occurred(unloading_occurred),
3417       _num_workers(num_workers),
3418       _first_nmethod(NULL),
3419       _claimed_nmethod(NULL),
3420       _postponed_list(NULL),
3421       _num_entered_barrier(0)
3422   {
3423     CompiledMethod::increase_unloading_clock();
3424     // Get first alive nmethod
3425     CompiledMethodIterator iter = CompiledMethodIterator();
3426     if(iter.next_alive()) {
3427       _first_nmethod = iter.method();
3428     }
3429     _claimed_nmethod = _first_nmethod;
3430   }
3431 
3432   ~G1CodeCacheUnloadingTask() {
3433     CodeCache::verify_clean_inline_caches();
3434 
3435     CodeCache::set_needs_cache_clean(false);
3436     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3437 
3438     CodeCache::verify_icholder_relocations();
3439   }
3440 
3441  private:
3442   void add_to_postponed_list(CompiledMethod* nm) {
3443       CompiledMethod* old;
3444       do {
3445         old = _postponed_list;
3446         nm->set_unloading_next(old);
3447       } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3448   }
3449 
3450   void clean_nmethod(CompiledMethod* nm) {
3451     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3452 
3453     if (postponed) {
3454       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3455       add_to_postponed_list(nm);
3456     }
3457 
3458     // Mark that this thread has been cleaned/unloaded.
3459     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3460     nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3461   }
3462 
3463   void clean_nmethod_postponed(CompiledMethod* nm) {
3464     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3465   }
3466 
3467   static const int MaxClaimNmethods = 16;
3468 
3469   void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3470     CompiledMethod* first;
3471     CompiledMethodIterator last;
3472 
3473     do {
3474       *num_claimed_nmethods = 0;
3475 
3476       first = _claimed_nmethod;
3477       last = CompiledMethodIterator(first);
3478 
3479       if (first != NULL) {
3480 
3481         for (int i = 0; i < MaxClaimNmethods; i++) {
3482           if (!last.next_alive()) {
3483             break;
3484           }
3485           claimed_nmethods[i] = last.method();
3486           (*num_claimed_nmethods)++;
3487         }
3488       }
3489 
3490     } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3491   }
3492 
3493   CompiledMethod* claim_postponed_nmethod() {
3494     CompiledMethod* claim;
3495     CompiledMethod* next;
3496 
3497     do {
3498       claim = _postponed_list;
3499       if (claim == NULL) {
3500         return NULL;
3501       }
3502 
3503       next = claim->unloading_next();
3504 
3505     } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3506 
3507     return claim;
3508   }
3509 
3510  public:
3511   // Mark that we're done with the first pass of nmethod cleaning.
3512   void barrier_mark(uint worker_id) {
3513     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3514     _num_entered_barrier++;
3515     if (_num_entered_barrier == _num_workers) {
3516       ml.notify_all();
3517     }
3518   }
3519 
3520   // See if we have to wait for the other workers to
3521   // finish their first-pass nmethod cleaning work.
3522   void barrier_wait(uint worker_id) {
3523     if (_num_entered_barrier < _num_workers) {
3524       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3525       while (_num_entered_barrier < _num_workers) {
3526           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3527       }
3528     }
3529   }
3530 
3531   // Cleaning and unloading of nmethods. Some work has to be postponed
3532   // to the second pass, when we know which nmethods survive.
3533   void work_first_pass(uint worker_id) {
3534     // The first nmethods is claimed by the first worker.
3535     if (worker_id == 0 && _first_nmethod != NULL) {
3536       clean_nmethod(_first_nmethod);
3537       _first_nmethod = NULL;
3538     }
3539 
3540     int num_claimed_nmethods;
3541     CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3542 
3543     while (true) {
3544       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3545 
3546       if (num_claimed_nmethods == 0) {
3547         break;
3548       }
3549 
3550       for (int i = 0; i < num_claimed_nmethods; i++) {
3551         clean_nmethod(claimed_nmethods[i]);
3552       }
3553     }
3554   }
3555 
3556   void work_second_pass(uint worker_id) {
3557     CompiledMethod* nm;
3558     // Take care of postponed nmethods.
3559     while ((nm = claim_postponed_nmethod()) != NULL) {
3560       clean_nmethod_postponed(nm);
3561     }
3562   }
3563 };
3564 
3565 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3566 
3567 class G1KlassCleaningTask : public StackObj {
3568   BoolObjectClosure*                      _is_alive;
3569   volatile int                            _clean_klass_tree_claimed;
3570   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3571 
3572  public:
3573   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3574       _is_alive(is_alive),
3575       _clean_klass_tree_claimed(0),
3576       _klass_iterator() {
3577   }
3578 
3579  private:
3580   bool claim_clean_klass_tree_task() {
3581     if (_clean_klass_tree_claimed) {
3582       return false;
3583     }
3584 
3585     return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3586   }
3587 
3588   InstanceKlass* claim_next_klass() {
3589     Klass* klass;
3590     do {
3591       klass =_klass_iterator.next_klass();
3592     } while (klass != NULL && !klass->is_instance_klass());
3593 
3594     // this can be null so don't call InstanceKlass::cast
3595     return static_cast<InstanceKlass*>(klass);
3596   }
3597 
3598 public:
3599 
3600   void clean_klass(InstanceKlass* ik) {
3601     ik->clean_weak_instanceklass_links(_is_alive);
3602   }
3603 
3604   void work() {
3605     ResourceMark rm;
3606 
3607     // One worker will clean the subklass/sibling klass tree.
3608     if (claim_clean_klass_tree_task()) {
3609       Klass::clean_subklass_tree(_is_alive);
3610     }
3611 
3612     // All workers will help cleaning the classes,
3613     InstanceKlass* klass;
3614     while ((klass = claim_next_klass()) != NULL) {
3615       clean_klass(klass);
3616     }
3617   }
3618 };
3619 
3620 class G1ResolvedMethodCleaningTask : public StackObj {
3621   BoolObjectClosure* _is_alive;
3622   volatile int       _resolved_method_task_claimed;
3623 public:
3624   G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3625       _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3626 
3627   bool claim_resolved_method_task() {
3628     if (_resolved_method_task_claimed) {
3629       return false;
3630     }
3631     return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3632   }
3633 
3634   // These aren't big, one thread can do it all.
3635   void work() {
3636     if (claim_resolved_method_task()) {
3637       ResolvedMethodTable::unlink(_is_alive);
3638     }
3639   }
3640 };
3641 
3642 
3643 // To minimize the remark pause times, the tasks below are done in parallel.
3644 class G1ParallelCleaningTask : public AbstractGangTask {
3645 private:
3646   G1StringAndSymbolCleaningTask _string_symbol_task;
3647   G1CodeCacheUnloadingTask      _code_cache_task;
3648   G1KlassCleaningTask           _klass_cleaning_task;
3649   G1ResolvedMethodCleaningTask  _resolved_method_cleaning_task;
3650 
3651 public:
3652   // The constructor is run in the VMThread.
3653   G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3654       AbstractGangTask("Parallel Cleaning"),
3655       _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3656       _code_cache_task(num_workers, is_alive, unloading_occurred),
3657       _klass_cleaning_task(is_alive),
3658       _resolved_method_cleaning_task(is_alive) {
3659   }
3660 
3661   // The parallel work done by all worker threads.
3662   void work(uint worker_id) {
3663     // Do first pass of code cache cleaning.
3664     _code_cache_task.work_first_pass(worker_id);
3665 
3666     // Let the threads mark that the first pass is done.
3667     _code_cache_task.barrier_mark(worker_id);
3668 
3669     // Clean the Strings and Symbols.
3670     _string_symbol_task.work(worker_id);
3671 
3672     // Clean unreferenced things in the ResolvedMethodTable
3673     _resolved_method_cleaning_task.work();
3674 
3675     // Wait for all workers to finish the first code cache cleaning pass.
3676     _code_cache_task.barrier_wait(worker_id);
3677 
3678     // Do the second code cache cleaning work, which realize on
3679     // the liveness information gathered during the first pass.
3680     _code_cache_task.work_second_pass(worker_id);
3681 
3682     // Clean all klasses that were not unloaded.
3683     _klass_cleaning_task.work();
3684   }
3685 };
3686 
3687 
3688 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3689                                         bool class_unloading_occurred) {
3690   uint n_workers = workers()->active_workers();
3691 
3692   G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3693   workers()->run_task(&g1_unlink_task);
3694 }
3695 
3696 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3697                                        bool process_strings,
3698                                        bool process_symbols,
3699                                        bool process_string_dedup) {
3700   if (!process_strings && !process_symbols && !process_string_dedup) {
3701     // Nothing to clean.
3702     return;
3703   }
3704 
3705   G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3706   workers()->run_task(&g1_unlink_task);
3707 
3708 }
3709 
3710 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3711  private:
3712   DirtyCardQueueSet* _queue;
3713   G1CollectedHeap* _g1h;
3714  public:
3715   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3716     _queue(queue), _g1h(g1h) { }
3717 
3718   virtual void work(uint worker_id) {
3719     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3720     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3721 
3722     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3723     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3724 
3725     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3726   }
3727 };
3728 
3729 void G1CollectedHeap::redirty_logged_cards() {
3730   double redirty_logged_cards_start = os::elapsedTime();
3731 
3732   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3733   dirty_card_queue_set().reset_for_par_iteration();
3734   workers()->run_task(&redirty_task);
3735 
3736   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3737   dcq.merge_bufferlists(&dirty_card_queue_set());
3738   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3739 
3740   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3741 }
3742 
3743 // Weak Reference Processing support
3744 
3745 // An always "is_alive" closure that is used to preserve referents.
3746 // If the object is non-null then it's alive.  Used in the preservation
3747 // of referent objects that are pointed to by reference objects
3748 // discovered by the CM ref processor.
3749 class G1AlwaysAliveClosure: public BoolObjectClosure {
3750   G1CollectedHeap* _g1;
3751 public:
3752   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3753   bool do_object_b(oop p) {
3754     if (p != NULL) {
3755       return true;
3756     }
3757     return false;
3758   }
3759 };
3760 
3761 bool G1STWIsAliveClosure::do_object_b(oop p) {
3762   // An object is reachable if it is outside the collection set,
3763   // or is inside and copied.
3764   return !_g1->is_in_cset(p) || p->is_forwarded();
3765 }
3766 
3767 // Non Copying Keep Alive closure
3768 class G1KeepAliveClosure: public OopClosure {
3769   G1CollectedHeap* _g1;
3770 public:
3771   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3772   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3773   void do_oop(oop* p) {
3774     oop obj = *p;
3775     assert(obj != NULL, "the caller should have filtered out NULL values");
3776 
3777     const InCSetState cset_state = _g1->in_cset_state(obj);
3778     if (!cset_state.is_in_cset_or_humongous()) {
3779       return;
3780     }
3781     if (cset_state.is_in_cset()) {
3782       assert( obj->is_forwarded(), "invariant" );
3783       *p = obj->forwardee();
3784     } else {
3785       assert(!obj->is_forwarded(), "invariant" );
3786       assert(cset_state.is_humongous(),
3787              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3788       _g1->set_humongous_is_live(obj);
3789     }
3790   }
3791 };
3792 
3793 // Copying Keep Alive closure - can be called from both
3794 // serial and parallel code as long as different worker
3795 // threads utilize different G1ParScanThreadState instances
3796 // and different queues.
3797 
3798 class G1CopyingKeepAliveClosure: public OopClosure {
3799   G1CollectedHeap*         _g1h;
3800   OopClosure*              _copy_non_heap_obj_cl;
3801   G1ParScanThreadState*    _par_scan_state;
3802 
3803 public:
3804   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3805                             OopClosure* non_heap_obj_cl,
3806                             G1ParScanThreadState* pss):
3807     _g1h(g1h),
3808     _copy_non_heap_obj_cl(non_heap_obj_cl),
3809     _par_scan_state(pss)
3810   {}
3811 
3812   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3813   virtual void do_oop(      oop* p) { do_oop_work(p); }
3814 
3815   template <class T> void do_oop_work(T* p) {
3816     oop obj = oopDesc::load_decode_heap_oop(p);
3817 
3818     if (_g1h->is_in_cset_or_humongous(obj)) {
3819       // If the referent object has been forwarded (either copied
3820       // to a new location or to itself in the event of an
3821       // evacuation failure) then we need to update the reference
3822       // field and, if both reference and referent are in the G1
3823       // heap, update the RSet for the referent.
3824       //
3825       // If the referent has not been forwarded then we have to keep
3826       // it alive by policy. Therefore we have copy the referent.
3827       //
3828       // If the reference field is in the G1 heap then we can push
3829       // on the PSS queue. When the queue is drained (after each
3830       // phase of reference processing) the object and it's followers
3831       // will be copied, the reference field set to point to the
3832       // new location, and the RSet updated. Otherwise we need to
3833       // use the the non-heap or metadata closures directly to copy
3834       // the referent object and update the pointer, while avoiding
3835       // updating the RSet.
3836 
3837       if (_g1h->is_in_g1_reserved(p)) {
3838         _par_scan_state->push_on_queue(p);
3839       } else {
3840         assert(!Metaspace::contains((const void*)p),
3841                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3842         _copy_non_heap_obj_cl->do_oop(p);
3843       }
3844     }
3845   }
3846 };
3847 
3848 // Serial drain queue closure. Called as the 'complete_gc'
3849 // closure for each discovered list in some of the
3850 // reference processing phases.
3851 
3852 class G1STWDrainQueueClosure: public VoidClosure {
3853 protected:
3854   G1CollectedHeap* _g1h;
3855   G1ParScanThreadState* _par_scan_state;
3856 
3857   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3858 
3859 public:
3860   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3861     _g1h(g1h),
3862     _par_scan_state(pss)
3863   { }
3864 
3865   void do_void() {
3866     G1ParScanThreadState* const pss = par_scan_state();
3867     pss->trim_queue();
3868   }
3869 };
3870 
3871 // Parallel Reference Processing closures
3872 
3873 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3874 // processing during G1 evacuation pauses.
3875 
3876 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3877 private:
3878   G1CollectedHeap*          _g1h;
3879   G1ParScanThreadStateSet*  _pss;
3880   RefToScanQueueSet*        _queues;
3881   WorkGang*                 _workers;
3882   uint                      _active_workers;
3883 
3884 public:
3885   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3886                            G1ParScanThreadStateSet* per_thread_states,
3887                            WorkGang* workers,
3888                            RefToScanQueueSet *task_queues,
3889                            uint n_workers) :
3890     _g1h(g1h),
3891     _pss(per_thread_states),
3892     _queues(task_queues),
3893     _workers(workers),
3894     _active_workers(n_workers)
3895   {
3896     g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3897   }
3898 
3899   // Executes the given task using concurrent marking worker threads.
3900   virtual void execute(ProcessTask& task);
3901   virtual void execute(EnqueueTask& task);
3902 };
3903 
3904 // Gang task for possibly parallel reference processing
3905 
3906 class G1STWRefProcTaskProxy: public AbstractGangTask {
3907   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3908   ProcessTask&     _proc_task;
3909   G1CollectedHeap* _g1h;
3910   G1ParScanThreadStateSet* _pss;
3911   RefToScanQueueSet* _task_queues;
3912   ParallelTaskTerminator* _terminator;
3913 
3914 public:
3915   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3916                         G1CollectedHeap* g1h,
3917                         G1ParScanThreadStateSet* per_thread_states,
3918                         RefToScanQueueSet *task_queues,
3919                         ParallelTaskTerminator* terminator) :
3920     AbstractGangTask("Process reference objects in parallel"),
3921     _proc_task(proc_task),
3922     _g1h(g1h),
3923     _pss(per_thread_states),
3924     _task_queues(task_queues),
3925     _terminator(terminator)
3926   {}
3927 
3928   virtual void work(uint worker_id) {
3929     // The reference processing task executed by a single worker.
3930     ResourceMark rm;
3931     HandleMark   hm;
3932 
3933     G1STWIsAliveClosure is_alive(_g1h);
3934 
3935     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
3936     pss->set_ref_processor(NULL);
3937 
3938     // Keep alive closure.
3939     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3940 
3941     // Complete GC closure
3942     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3943 
3944     // Call the reference processing task's work routine.
3945     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3946 
3947     // Note we cannot assert that the refs array is empty here as not all
3948     // of the processing tasks (specifically phase2 - pp2_work) execute
3949     // the complete_gc closure (which ordinarily would drain the queue) so
3950     // the queue may not be empty.
3951   }
3952 };
3953 
3954 // Driver routine for parallel reference processing.
3955 // Creates an instance of the ref processing gang
3956 // task and has the worker threads execute it.
3957 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3958   assert(_workers != NULL, "Need parallel worker threads.");
3959 
3960   ParallelTaskTerminator terminator(_active_workers, _queues);
3961   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3962 
3963   _workers->run_task(&proc_task_proxy);
3964 }
3965 
3966 // Gang task for parallel reference enqueueing.
3967 
3968 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
3969   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
3970   EnqueueTask& _enq_task;
3971 
3972 public:
3973   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
3974     AbstractGangTask("Enqueue reference objects in parallel"),
3975     _enq_task(enq_task)
3976   { }
3977 
3978   virtual void work(uint worker_id) {
3979     _enq_task.work(worker_id);
3980   }
3981 };
3982 
3983 // Driver routine for parallel reference enqueueing.
3984 // Creates an instance of the ref enqueueing gang
3985 // task and has the worker threads execute it.
3986 
3987 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
3988   assert(_workers != NULL, "Need parallel worker threads.");
3989 
3990   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
3991 
3992   _workers->run_task(&enq_task_proxy);
3993 }
3994 
3995 // End of weak reference support closures
3996 
3997 // Abstract task used to preserve (i.e. copy) any referent objects
3998 // that are in the collection set and are pointed to by reference
3999 // objects discovered by the CM ref processor.
4000 
4001 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4002 protected:
4003   G1CollectedHeap*         _g1h;
4004   G1ParScanThreadStateSet* _pss;
4005   RefToScanQueueSet*       _queues;
4006   ParallelTaskTerminator   _terminator;
4007   uint                     _n_workers;
4008 
4009 public:
4010   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4011     AbstractGangTask("ParPreserveCMReferents"),
4012     _g1h(g1h),
4013     _pss(per_thread_states),
4014     _queues(task_queues),
4015     _terminator(workers, _queues),
4016     _n_workers(workers)
4017   {
4018     g1h->ref_processor_cm()->set_active_mt_degree(workers);
4019   }
4020 
4021   void work(uint worker_id) {
4022     G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4023 
4024     ResourceMark rm;
4025     HandleMark   hm;
4026 
4027     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4028     pss->set_ref_processor(NULL);
4029     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4030 
4031     // Is alive closure
4032     G1AlwaysAliveClosure always_alive(_g1h);
4033 
4034     // Copying keep alive closure. Applied to referent objects that need
4035     // to be copied.
4036     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4037 
4038     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4039 
4040     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4041     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4042 
4043     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4044     // So this must be true - but assert just in case someone decides to
4045     // change the worker ids.
4046     assert(worker_id < limit, "sanity");
4047     assert(!rp->discovery_is_atomic(), "check this code");
4048 
4049     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4050     for (uint idx = worker_id; idx < limit; idx += stride) {
4051       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4052 
4053       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4054       while (iter.has_next()) {
4055         // Since discovery is not atomic for the CM ref processor, we
4056         // can see some null referent objects.
4057         iter.load_ptrs(DEBUG_ONLY(true));
4058         oop ref = iter.obj();
4059 
4060         // This will filter nulls.
4061         if (iter.is_referent_alive()) {
4062           iter.make_referent_alive();
4063         }
4064         iter.move_to_next();
4065       }
4066     }
4067 
4068     // Drain the queue - which may cause stealing
4069     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4070     drain_queue.do_void();
4071     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4072     assert(pss->queue_is_empty(), "should be");
4073   }
4074 };
4075 
4076 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4077   // Any reference objects, in the collection set, that were 'discovered'
4078   // by the CM ref processor should have already been copied (either by
4079   // applying the external root copy closure to the discovered lists, or
4080   // by following an RSet entry).
4081   //
4082   // But some of the referents, that are in the collection set, that these
4083   // reference objects point to may not have been copied: the STW ref
4084   // processor would have seen that the reference object had already
4085   // been 'discovered' and would have skipped discovering the reference,
4086   // but would not have treated the reference object as a regular oop.
4087   // As a result the copy closure would not have been applied to the
4088   // referent object.
4089   //
4090   // We need to explicitly copy these referent objects - the references
4091   // will be processed at the end of remarking.
4092   //
4093   // We also need to do this copying before we process the reference
4094   // objects discovered by the STW ref processor in case one of these
4095   // referents points to another object which is also referenced by an
4096   // object discovered by the STW ref processor.
4097   double preserve_cm_referents_time = 0.0;
4098 
4099   // To avoid spawning task when there is no work to do, check that
4100   // a concurrent cycle is active and that some references have been
4101   // discovered.
4102   if (concurrent_mark()->cm_thread()->during_cycle() &&
4103       ref_processor_cm()->has_discovered_references()) {
4104     double preserve_cm_referents_start = os::elapsedTime();
4105     uint no_of_gc_workers = workers()->active_workers();
4106     G1ParPreserveCMReferentsTask keep_cm_referents(this,
4107                                                    per_thread_states,
4108                                                    no_of_gc_workers,
4109                                                    _task_queues);
4110     workers()->run_task(&keep_cm_referents);
4111     preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4112   }
4113 
4114   g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4115 }
4116 
4117 // Weak Reference processing during an evacuation pause (part 1).
4118 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4119   double ref_proc_start = os::elapsedTime();
4120 
4121   ReferenceProcessor* rp = _ref_processor_stw;
4122   assert(rp->discovery_enabled(), "should have been enabled");
4123 
4124   // Closure to test whether a referent is alive.
4125   G1STWIsAliveClosure is_alive(this);
4126 
4127   // Even when parallel reference processing is enabled, the processing
4128   // of JNI refs is serial and performed serially by the current thread
4129   // rather than by a worker. The following PSS will be used for processing
4130   // JNI refs.
4131 
4132   // Use only a single queue for this PSS.
4133   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4134   pss->set_ref_processor(NULL);
4135   assert(pss->queue_is_empty(), "pre-condition");
4136 
4137   // Keep alive closure.
4138   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4139 
4140   // Serial Complete GC closure
4141   G1STWDrainQueueClosure drain_queue(this, pss);
4142 
4143   // Setup the soft refs policy...
4144   rp->setup_policy(false);
4145 
4146   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4147 
4148   ReferenceProcessorStats stats;
4149   if (!rp->processing_is_mt()) {
4150     // Serial reference processing...
4151     stats = rp->process_discovered_references(&is_alive,
4152                                               &keep_alive,
4153                                               &drain_queue,
4154                                               NULL,
4155                                               pt);
4156   } else {
4157     uint no_of_gc_workers = workers()->active_workers();
4158 
4159     // Parallel reference processing
4160     assert(no_of_gc_workers <= rp->max_num_q(),
4161            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4162            no_of_gc_workers,  rp->max_num_q());
4163 
4164     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4165     stats = rp->process_discovered_references(&is_alive,
4166                                               &keep_alive,
4167                                               &drain_queue,
4168                                               &par_task_executor,
4169                                               pt);
4170   }
4171 
4172   _gc_tracer_stw->report_gc_reference_stats(stats);
4173 
4174   // We have completed copying any necessary live referent objects.
4175   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4176 
4177   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4178   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4179 }
4180 
4181 // Weak Reference processing during an evacuation pause (part 2).
4182 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4183   double ref_enq_start = os::elapsedTime();
4184 
4185   ReferenceProcessor* rp = _ref_processor_stw;
4186   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4187 
4188   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4189 
4190   // Now enqueue any remaining on the discovered lists on to
4191   // the pending list.
4192   if (!rp->processing_is_mt()) {
4193     // Serial reference processing...
4194     rp->enqueue_discovered_references(NULL, pt);
4195   } else {
4196     // Parallel reference enqueueing
4197 
4198     uint n_workers = workers()->active_workers();
4199 
4200     assert(n_workers <= rp->max_num_q(),
4201            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4202            n_workers,  rp->max_num_q());
4203 
4204     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4205     rp->enqueue_discovered_references(&par_task_executor, pt);
4206   }
4207 
4208   rp->verify_no_references_recorded();
4209   assert(!rp->discovery_enabled(), "should have been disabled");
4210 
4211   // If during an initial mark pause we install a pending list head which is not otherwise reachable
4212   // ensure that it is marked in the bitmap for concurrent marking to discover.
4213   if (collector_state()->during_initial_mark_pause()) {
4214     oop pll_head = Universe::reference_pending_list();
4215     if (pll_head != NULL) {
4216       _cm->mark_in_next_bitmap(pll_head);
4217     }
4218   }
4219 
4220   // FIXME
4221   // CM's reference processing also cleans up the string and symbol tables.
4222   // Should we do that here also? We could, but it is a serial operation
4223   // and could significantly increase the pause time.
4224 
4225   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4226   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4227 }
4228 
4229 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4230   double merge_pss_time_start = os::elapsedTime();
4231   per_thread_states->flush();
4232   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4233 }
4234 
4235 void G1CollectedHeap::pre_evacuate_collection_set() {
4236   _expand_heap_after_alloc_failure = true;
4237   _evacuation_failed = false;
4238 
4239   // Disable the hot card cache.
4240   _hot_card_cache->reset_hot_cache_claimed_index();
4241   _hot_card_cache->set_use_cache(false);
4242 
4243   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4244   _preserved_marks_set.assert_empty();
4245 
4246   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4247 
4248   // InitialMark needs claim bits to keep track of the marked-through CLDs.
4249   if (collector_state()->during_initial_mark_pause()) {
4250     double start_clear_claimed_marks = os::elapsedTime();
4251 
4252     ClassLoaderDataGraph::clear_claimed_marks();
4253 
4254     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4255     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4256   }
4257 }
4258 
4259 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
4260   // Should G1EvacuationFailureALot be in effect for this GC?
4261   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4262 
4263   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4264 
4265   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4266 
4267   double start_par_time_sec = os::elapsedTime();
4268   double end_par_time_sec;
4269 
4270   {
4271     const uint n_workers = workers()->active_workers();
4272     G1RootProcessor root_processor(this, n_workers);
4273     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4274 
4275     print_termination_stats_hdr();
4276 
4277     workers()->run_task(&g1_par_task);
4278     end_par_time_sec = os::elapsedTime();
4279 
4280     // Closing the inner scope will execute the destructor
4281     // for the G1RootProcessor object. We record the current
4282     // elapsed time before closing the scope so that time
4283     // taken for the destructor is NOT included in the
4284     // reported parallel time.
4285   }
4286 
4287   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4288   phase_times->record_par_time(par_time_ms);
4289 
4290   double code_root_fixup_time_ms =
4291         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4292   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4293 }
4294 
4295 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4296   // Process any discovered reference objects - we have
4297   // to do this _before_ we retire the GC alloc regions
4298   // as we may have to copy some 'reachable' referent
4299   // objects (and their reachable sub-graphs) that were
4300   // not copied during the pause.
4301   if (g1_policy()->should_process_references()) {
4302     preserve_cm_referents(per_thread_states);
4303     process_discovered_references(per_thread_states);
4304   } else {
4305     ref_processor_stw()->verify_no_references_recorded();
4306   }
4307 
4308   G1STWIsAliveClosure is_alive(this);
4309   G1KeepAliveClosure keep_alive(this);
4310 
4311   {
4312     double start = os::elapsedTime();
4313 
4314     WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4315 
4316     double time_ms = (os::elapsedTime() - start) * 1000.0;
4317     g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4318   }
4319 
4320   if (G1StringDedup::is_enabled()) {
4321     double fixup_start = os::elapsedTime();
4322 
4323     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4324 
4325     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4326     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4327   }
4328 
4329   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4330 
4331   if (evacuation_failed()) {
4332     restore_after_evac_failure();
4333 
4334     // Reset the G1EvacuationFailureALot counters and flags
4335     // Note: the values are reset only when an actual
4336     // evacuation failure occurs.
4337     NOT_PRODUCT(reset_evacuation_should_fail();)
4338   }
4339 
4340   _preserved_marks_set.assert_empty();
4341 
4342   // Enqueue any remaining references remaining on the STW
4343   // reference processor's discovered lists. We need to do
4344   // this after the card table is cleaned (and verified) as
4345   // the act of enqueueing entries on to the pending list
4346   // will log these updates (and dirty their associated
4347   // cards). We need these updates logged to update any
4348   // RSets.
4349   if (g1_policy()->should_process_references()) {
4350     enqueue_discovered_references(per_thread_states);
4351   } else {
4352     g1_policy()->phase_times()->record_ref_enq_time(0);
4353   }
4354 
4355   _allocator->release_gc_alloc_regions(evacuation_info);
4356 
4357   merge_per_thread_state_info(per_thread_states);
4358 
4359   // Reset and re-enable the hot card cache.
4360   // Note the counts for the cards in the regions in the
4361   // collection set are reset when the collection set is freed.
4362   _hot_card_cache->reset_hot_cache();
4363   _hot_card_cache->set_use_cache(true);
4364 
4365   purge_code_root_memory();
4366 
4367   redirty_logged_cards();
4368 #if COMPILER2_OR_JVMCI
4369   double start = os::elapsedTime();
4370   DerivedPointerTable::update_pointers();
4371   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4372 #endif
4373   g1_policy()->print_age_table();
4374 }
4375 
4376 void G1CollectedHeap::record_obj_copy_mem_stats() {
4377   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4378 
4379   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4380                                                create_g1_evac_summary(&_old_evac_stats));
4381 }
4382 
4383 void G1CollectedHeap::free_region(HeapRegion* hr,
4384                                   FreeRegionList* free_list,
4385                                   bool skip_remset,
4386                                   bool skip_hot_card_cache,
4387                                   bool locked) {
4388   assert(!hr->is_free(), "the region should not be free");
4389   assert(!hr->is_empty(), "the region should not be empty");
4390   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4391   assert(free_list != NULL, "pre-condition");
4392 
4393   if (G1VerifyBitmaps) {
4394     MemRegion mr(hr->bottom(), hr->end());
4395     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4396   }
4397 
4398   // Clear the card counts for this region.
4399   // Note: we only need to do this if the region is not young
4400   // (since we don't refine cards in young regions).
4401   if (!skip_hot_card_cache && !hr->is_young()) {
4402     _hot_card_cache->reset_card_counts(hr);
4403   }
4404   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4405   free_list->add_ordered(hr);
4406 }
4407 
4408 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4409                                             FreeRegionList* free_list,
4410                                             bool skip_remset) {
4411   assert(hr->is_humongous(), "this is only for humongous regions");
4412   assert(free_list != NULL, "pre-condition");
4413   hr->clear_humongous();
4414   free_region(hr, free_list, skip_remset);
4415 }
4416 
4417 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4418                                            const uint humongous_regions_removed) {
4419   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4420     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4421     _old_set.bulk_remove(old_regions_removed);
4422     _humongous_set.bulk_remove(humongous_regions_removed);
4423   }
4424 
4425 }
4426 
4427 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4428   assert(list != NULL, "list can't be null");
4429   if (!list->is_empty()) {
4430     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4431     _hrm.insert_list_into_free_list(list);
4432   }
4433 }
4434 
4435 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4436   decrease_used(bytes);
4437 }
4438 
4439 class G1ParScrubRemSetTask: public AbstractGangTask {
4440 protected:
4441   G1RemSet* _g1rs;
4442   HeapRegionClaimer _hrclaimer;
4443 
4444 public:
4445   G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4446     AbstractGangTask("G1 ScrubRS"),
4447     _g1rs(g1_rs),
4448     _hrclaimer(num_workers) {
4449   }
4450 
4451   void work(uint worker_id) {
4452     _g1rs->scrub(worker_id, &_hrclaimer);
4453   }
4454 };
4455 
4456 void G1CollectedHeap::scrub_rem_set() {
4457   uint num_workers = workers()->active_workers();
4458   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4459   workers()->run_task(&g1_par_scrub_rs_task);
4460 }
4461 
4462 class G1FreeCollectionSetTask : public AbstractGangTask {
4463 private:
4464 
4465   // Closure applied to all regions in the collection set to do work that needs to
4466   // be done serially in a single thread.
4467   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4468   private:
4469     EvacuationInfo* _evacuation_info;
4470     const size_t* _surviving_young_words;
4471 
4472     // Bytes used in successfully evacuated regions before the evacuation.
4473     size_t _before_used_bytes;
4474     // Bytes used in unsucessfully evacuated regions before the evacuation
4475     size_t _after_used_bytes;
4476 
4477     size_t _bytes_allocated_in_old_since_last_gc;
4478 
4479     size_t _failure_used_words;
4480     size_t _failure_waste_words;
4481 
4482     FreeRegionList _local_free_list;
4483   public:
4484     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4485       HeapRegionClosure(),
4486       _evacuation_info(evacuation_info),
4487       _surviving_young_words(surviving_young_words),
4488       _before_used_bytes(0),
4489       _after_used_bytes(0),
4490       _bytes_allocated_in_old_since_last_gc(0),
4491       _failure_used_words(0),
4492       _failure_waste_words(0),
4493       _local_free_list("Local Region List for CSet Freeing") {
4494     }
4495 
4496     virtual bool do_heap_region(HeapRegion* r) {
4497       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4498 
4499       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4500       g1h->clear_in_cset(r);
4501 
4502       if (r->is_young()) {
4503         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4504                "Young index %d is wrong for region %u of type %s with %u young regions",
4505                r->young_index_in_cset(),
4506                r->hrm_index(),
4507                r->get_type_str(),
4508                g1h->collection_set()->young_region_length());
4509         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4510         r->record_surv_words_in_group(words_survived);
4511       }
4512 
4513       if (!r->evacuation_failed()) {
4514         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4515         _before_used_bytes += r->used();
4516         g1h->free_region(r,
4517                          &_local_free_list,
4518                          true, /* skip_remset */
4519                          true, /* skip_hot_card_cache */
4520                          true  /* locked */);
4521       } else {
4522         r->uninstall_surv_rate_group();
4523         r->set_young_index_in_cset(-1);
4524         r->set_evacuation_failed(false);
4525         // When moving a young gen region to old gen, we "allocate" that whole region
4526         // there. This is in addition to any already evacuated objects. Notify the
4527         // policy about that.
4528         // Old gen regions do not cause an additional allocation: both the objects
4529         // still in the region and the ones already moved are accounted for elsewhere.
4530         if (r->is_young()) {
4531           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4532         }
4533         // The region is now considered to be old.
4534         r->set_old();
4535         // Do some allocation statistics accounting. Regions that failed evacuation
4536         // are always made old, so there is no need to update anything in the young
4537         // gen statistics, but we need to update old gen statistics.
4538         size_t used_words = r->marked_bytes() / HeapWordSize;
4539 
4540         _failure_used_words += used_words;
4541         _failure_waste_words += HeapRegion::GrainWords - used_words;
4542 
4543         g1h->old_set_add(r);
4544         _after_used_bytes += r->used();
4545       }
4546       return false;
4547     }
4548 
4549     void complete_work() {
4550       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4551 
4552       _evacuation_info->set_regions_freed(_local_free_list.length());
4553       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4554 
4555       g1h->prepend_to_freelist(&_local_free_list);
4556       g1h->decrement_summary_bytes(_before_used_bytes);
4557 
4558       G1Policy* policy = g1h->g1_policy();
4559       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4560 
4561       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4562     }
4563   };
4564 
4565   G1CollectionSet* _collection_set;
4566   G1SerialFreeCollectionSetClosure _cl;
4567   const size_t* _surviving_young_words;
4568 
4569   size_t _rs_lengths;
4570 
4571   volatile jint _serial_work_claim;
4572 
4573   struct WorkItem {
4574     uint region_idx;
4575     bool is_young;
4576     bool evacuation_failed;
4577 
4578     WorkItem(HeapRegion* r) {
4579       region_idx = r->hrm_index();
4580       is_young = r->is_young();
4581       evacuation_failed = r->evacuation_failed();
4582     }
4583   };
4584 
4585   volatile size_t _parallel_work_claim;
4586   size_t _num_work_items;
4587   WorkItem* _work_items;
4588 
4589   void do_serial_work() {
4590     // Need to grab the lock to be allowed to modify the old region list.
4591     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4592     _collection_set->iterate(&_cl);
4593   }
4594 
4595   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4596     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4597 
4598     HeapRegion* r = g1h->region_at(region_idx);
4599     assert(!g1h->is_on_master_free_list(r), "sanity");
4600 
4601     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4602 
4603     if (!is_young) {
4604       g1h->_hot_card_cache->reset_card_counts(r);
4605     }
4606 
4607     if (!evacuation_failed) {
4608       r->rem_set()->clear_locked();
4609     }
4610   }
4611 
4612   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4613   private:
4614     size_t _cur_idx;
4615     WorkItem* _work_items;
4616   public:
4617     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4618 
4619     virtual bool do_heap_region(HeapRegion* r) {
4620       _work_items[_cur_idx++] = WorkItem(r);
4621       return false;
4622     }
4623   };
4624 
4625   void prepare_work() {
4626     G1PrepareFreeCollectionSetClosure cl(_work_items);
4627     _collection_set->iterate(&cl);
4628   }
4629 
4630   void complete_work() {
4631     _cl.complete_work();
4632 
4633     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4634     policy->record_max_rs_lengths(_rs_lengths);
4635     policy->cset_regions_freed();
4636   }
4637 public:
4638   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4639     AbstractGangTask("G1 Free Collection Set"),
4640     _cl(evacuation_info, surviving_young_words),
4641     _collection_set(collection_set),
4642     _surviving_young_words(surviving_young_words),
4643     _serial_work_claim(0),
4644     _rs_lengths(0),
4645     _parallel_work_claim(0),
4646     _num_work_items(collection_set->region_length()),
4647     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4648     prepare_work();
4649   }
4650 
4651   ~G1FreeCollectionSetTask() {
4652     complete_work();
4653     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4654   }
4655 
4656   // Chunk size for work distribution. The chosen value has been determined experimentally
4657   // to be a good tradeoff between overhead and achievable parallelism.
4658   static uint chunk_size() { return 32; }
4659 
4660   virtual void work(uint worker_id) {
4661     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4662 
4663     // Claim serial work.
4664     if (_serial_work_claim == 0) {
4665       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4666       if (value == 0) {
4667         double serial_time = os::elapsedTime();
4668         do_serial_work();
4669         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4670       }
4671     }
4672 
4673     // Start parallel work.
4674     double young_time = 0.0;
4675     bool has_young_time = false;
4676     double non_young_time = 0.0;
4677     bool has_non_young_time = false;
4678 
4679     while (true) {
4680       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4681       size_t cur = end - chunk_size();
4682 
4683       if (cur >= _num_work_items) {
4684         break;
4685       }
4686 
4687       double start_time = os::elapsedTime();
4688 
4689       end = MIN2(end, _num_work_items);
4690 
4691       for (; cur < end; cur++) {
4692         bool is_young = _work_items[cur].is_young;
4693 
4694         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4695 
4696         double end_time = os::elapsedTime();
4697         double time_taken = end_time - start_time;
4698         if (is_young) {
4699           young_time += time_taken;
4700           has_young_time = true;
4701         } else {
4702           non_young_time += time_taken;
4703           has_non_young_time = true;
4704         }
4705         start_time = end_time;
4706       }
4707     }
4708 
4709     if (has_young_time) {
4710       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4711     }
4712     if (has_non_young_time) {
4713       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4714     }
4715   }
4716 };
4717 
4718 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4719   _eden.clear();
4720 
4721   double free_cset_start_time = os::elapsedTime();
4722 
4723   {
4724     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4725     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4726 
4727     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4728 
4729     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4730                         cl.name(),
4731                         num_workers,
4732                         _collection_set.region_length());
4733     workers()->run_task(&cl, num_workers);
4734   }
4735   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4736 
4737   collection_set->clear();
4738 }
4739 
4740 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4741  private:
4742   FreeRegionList* _free_region_list;
4743   HeapRegionSet* _proxy_set;
4744   uint _humongous_objects_reclaimed;
4745   uint _humongous_regions_reclaimed;
4746   size_t _freed_bytes;
4747  public:
4748 
4749   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4750     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4751   }
4752 
4753   virtual bool do_heap_region(HeapRegion* r) {
4754     if (!r->is_starts_humongous()) {
4755       return false;
4756     }
4757 
4758     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4759 
4760     oop obj = (oop)r->bottom();
4761     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4762 
4763     // The following checks whether the humongous object is live are sufficient.
4764     // The main additional check (in addition to having a reference from the roots
4765     // or the young gen) is whether the humongous object has a remembered set entry.
4766     //
4767     // A humongous object cannot be live if there is no remembered set for it
4768     // because:
4769     // - there can be no references from within humongous starts regions referencing
4770     // the object because we never allocate other objects into them.
4771     // (I.e. there are no intra-region references that may be missed by the
4772     // remembered set)
4773     // - as soon there is a remembered set entry to the humongous starts region
4774     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4775     // until the end of a concurrent mark.
4776     //
4777     // It is not required to check whether the object has been found dead by marking
4778     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4779     // all objects allocated during that time are considered live.
4780     // SATB marking is even more conservative than the remembered set.
4781     // So if at this point in the collection there is no remembered set entry,
4782     // nobody has a reference to it.
4783     // At the start of collection we flush all refinement logs, and remembered sets
4784     // are completely up-to-date wrt to references to the humongous object.
4785     //
4786     // Other implementation considerations:
4787     // - never consider object arrays at this time because they would pose
4788     // considerable effort for cleaning up the the remembered sets. This is
4789     // required because stale remembered sets might reference locations that
4790     // are currently allocated into.
4791     uint region_idx = r->hrm_index();
4792     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4793         !r->rem_set()->is_empty()) {
4794       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",
4795                                region_idx,
4796                                (size_t)obj->size() * HeapWordSize,
4797                                p2i(r->bottom()),
4798                                r->rem_set()->occupied(),
4799                                r->rem_set()->strong_code_roots_list_length(),
4800                                next_bitmap->is_marked(r->bottom()),
4801                                g1h->is_humongous_reclaim_candidate(region_idx),
4802                                obj->is_typeArray()
4803                               );
4804       return false;
4805     }
4806 
4807     guarantee(obj->is_typeArray(),
4808               "Only eagerly reclaiming type arrays is supported, but the object "
4809               PTR_FORMAT " is not.", p2i(r->bottom()));
4810 
4811     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",
4812                              region_idx,
4813                              (size_t)obj->size() * HeapWordSize,
4814                              p2i(r->bottom()),
4815                              r->rem_set()->occupied(),
4816                              r->rem_set()->strong_code_roots_list_length(),
4817                              next_bitmap->is_marked(r->bottom()),
4818                              g1h->is_humongous_reclaim_candidate(region_idx),
4819                              obj->is_typeArray()
4820                             );
4821 
4822     g1h->concurrent_mark()->humongous_object_eagerly_reclaimed(r);
4823     _humongous_objects_reclaimed++;
4824     do {
4825       HeapRegion* next = g1h->next_region_in_humongous(r);
4826       _freed_bytes += r->used();
4827       r->set_containing_set(NULL);
4828       _humongous_regions_reclaimed++;
4829       g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4830       r = next;
4831     } while (r != NULL);
4832 
4833     return false;
4834   }
4835 
4836   uint humongous_objects_reclaimed() {
4837     return _humongous_objects_reclaimed;
4838   }
4839 
4840   uint humongous_regions_reclaimed() {
4841     return _humongous_regions_reclaimed;
4842   }
4843 
4844   size_t bytes_freed() const {
4845     return _freed_bytes;
4846   }
4847 };
4848 
4849 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4850   assert_at_safepoint_on_vm_thread();
4851 
4852   if (!G1EagerReclaimHumongousObjects ||
4853       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4854     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4855     return;
4856   }
4857 
4858   double start_time = os::elapsedTime();
4859 
4860   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4861 
4862   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4863   heap_region_iterate(&cl);
4864 
4865   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4866 
4867   G1HRPrinter* hrp = hr_printer();
4868   if (hrp->is_active()) {
4869     FreeRegionListIterator iter(&local_cleanup_list);
4870     while (iter.more_available()) {
4871       HeapRegion* hr = iter.get_next();
4872       hrp->cleanup(hr);
4873     }
4874   }
4875 
4876   prepend_to_freelist(&local_cleanup_list);
4877   decrement_summary_bytes(cl.bytes_freed());
4878 
4879   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4880                                                                     cl.humongous_objects_reclaimed());
4881 }
4882 
4883 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4884 public:
4885   virtual bool do_heap_region(HeapRegion* r) {
4886     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4887     G1CollectedHeap::heap()->clear_in_cset(r);
4888     r->set_young_index_in_cset(-1);
4889     return false;
4890   }
4891 };
4892 
4893 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4894   G1AbandonCollectionSetClosure cl;
4895   collection_set->iterate(&cl);
4896 
4897   collection_set->clear();
4898   collection_set->stop_incremental_building();
4899 }
4900 
4901 void G1CollectedHeap::set_free_regions_coming() {
4902   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4903 
4904   assert(!free_regions_coming(), "pre-condition");
4905   _free_regions_coming = true;
4906 }
4907 
4908 void G1CollectedHeap::reset_free_regions_coming() {
4909   assert(free_regions_coming(), "pre-condition");
4910 
4911   {
4912     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4913     _free_regions_coming = false;
4914     SecondaryFreeList_lock->notify_all();
4915   }
4916 
4917   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4918 }
4919 
4920 void G1CollectedHeap::wait_while_free_regions_coming() {
4921   // Most of the time we won't have to wait, so let's do a quick test
4922   // first before we take the lock.
4923   if (!free_regions_coming()) {
4924     return;
4925   }
4926 
4927   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4928 
4929   {
4930     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4931     while (free_regions_coming()) {
4932       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4933     }
4934   }
4935 
4936   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
4937 }
4938 
4939 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4940   return _allocator->is_retained_old_region(hr);
4941 }
4942 
4943 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4944   _eden.add(hr);
4945   _g1_policy->set_region_eden(hr);
4946 }
4947 
4948 #ifdef ASSERT
4949 
4950 class NoYoungRegionsClosure: public HeapRegionClosure {
4951 private:
4952   bool _success;
4953 public:
4954   NoYoungRegionsClosure() : _success(true) { }
4955   bool do_heap_region(HeapRegion* r) {
4956     if (r->is_young()) {
4957       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4958                             p2i(r->bottom()), p2i(r->end()));
4959       _success = false;
4960     }
4961     return false;
4962   }
4963   bool success() { return _success; }
4964 };
4965 
4966 bool G1CollectedHeap::check_young_list_empty() {
4967   bool ret = (young_regions_count() == 0);
4968 
4969   NoYoungRegionsClosure closure;
4970   heap_region_iterate(&closure);
4971   ret = ret && closure.success();
4972 
4973   return ret;
4974 }
4975 
4976 #endif // ASSERT
4977 
4978 class TearDownRegionSetsClosure : public HeapRegionClosure {
4979 private:
4980   HeapRegionSet *_old_set;
4981 
4982 public:
4983   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4984 
4985   bool do_heap_region(HeapRegion* r) {
4986     if (r->is_old()) {
4987       _old_set->remove(r);
4988     } else if(r->is_young()) {
4989       r->uninstall_surv_rate_group();
4990     } else {
4991       // We ignore free regions, we'll empty the free list afterwards.
4992       // We ignore humongous regions, we're not tearing down the
4993       // humongous regions set.
4994       assert(r->is_free() || r->is_humongous(),
4995              "it cannot be another type");
4996     }
4997     return false;
4998   }
4999 
5000   ~TearDownRegionSetsClosure() {
5001     assert(_old_set->is_empty(), "post-condition");
5002   }
5003 };
5004 
5005 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5006   assert_at_safepoint_on_vm_thread();
5007 
5008   if (!free_list_only) {
5009     TearDownRegionSetsClosure cl(&_old_set);
5010     heap_region_iterate(&cl);
5011 
5012     // Note that emptying the _young_list is postponed and instead done as
5013     // the first step when rebuilding the regions sets again. The reason for
5014     // this is that during a full GC string deduplication needs to know if
5015     // a collected region was young or old when the full GC was initiated.
5016   }
5017   _hrm.remove_all_free_regions();
5018 }
5019 
5020 void G1CollectedHeap::increase_used(size_t bytes) {
5021   _summary_bytes_used += bytes;
5022 }
5023 
5024 void G1CollectedHeap::decrease_used(size_t bytes) {
5025   assert(_summary_bytes_used >= bytes,
5026          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5027          _summary_bytes_used, bytes);
5028   _summary_bytes_used -= bytes;
5029 }
5030 
5031 void G1CollectedHeap::set_used(size_t bytes) {
5032   _summary_bytes_used = bytes;
5033 }
5034 
5035 class RebuildRegionSetsClosure : public HeapRegionClosure {
5036 private:
5037   bool            _free_list_only;
5038   HeapRegionSet*   _old_set;
5039   HeapRegionManager*   _hrm;
5040   size_t          _total_used;
5041 
5042 public:
5043   RebuildRegionSetsClosure(bool free_list_only,
5044                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5045     _free_list_only(free_list_only),
5046     _old_set(old_set), _hrm(hrm), _total_used(0) {
5047     assert(_hrm->num_free_regions() == 0, "pre-condition");
5048     if (!free_list_only) {
5049       assert(_old_set->is_empty(), "pre-condition");
5050     }
5051   }
5052 
5053   bool do_heap_region(HeapRegion* r) {
5054     if (r->is_empty()) {
5055       // Add free regions to the free list
5056       r->set_free();
5057       _hrm->insert_into_free_list(r);
5058     } else if (!_free_list_only) {
5059 
5060       if (r->is_humongous()) {
5061         // We ignore humongous regions. We left the humongous set unchanged.
5062       } else {
5063         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5064         // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5065         r->move_to_old();
5066         _old_set->add(r);
5067       }
5068       _total_used += r->used();
5069     }
5070 
5071     return false;
5072   }
5073 
5074   size_t total_used() {
5075     return _total_used;
5076   }
5077 };
5078 
5079 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5080   assert_at_safepoint_on_vm_thread();
5081 
5082   if (!free_list_only) {
5083     _eden.clear();
5084     _survivor.clear();
5085   }
5086 
5087   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5088   heap_region_iterate(&cl);
5089 
5090   if (!free_list_only) {
5091     set_used(cl.total_used());
5092     if (_archive_allocator != NULL) {
5093       _archive_allocator->clear_used();
5094     }
5095   }
5096   assert(used_unlocked() == recalculate_used(),
5097          "inconsistent used_unlocked(), "
5098          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5099          used_unlocked(), recalculate_used());
5100 }
5101 
5102 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5103   HeapRegion* hr = heap_region_containing(p);
5104   return hr->is_in(p);
5105 }
5106 
5107 // Methods for the mutator alloc region
5108 
5109 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5110                                                       bool force) {
5111   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5112   bool should_allocate = g1_policy()->should_allocate_mutator_region();
5113   if (force || should_allocate) {
5114     HeapRegion* new_alloc_region = new_region(word_size,
5115                                               false /* is_old */,
5116                                               false /* do_expand */);
5117     if (new_alloc_region != NULL) {
5118       set_region_short_lived_locked(new_alloc_region);
5119       _hr_printer.alloc(new_alloc_region, !should_allocate);
5120       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5121       return new_alloc_region;
5122     }
5123   }
5124   return NULL;
5125 }
5126 
5127 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5128                                                   size_t allocated_bytes) {
5129   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5130   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5131 
5132   collection_set()->add_eden_region(alloc_region);
5133   increase_used(allocated_bytes);
5134   _hr_printer.retire(alloc_region);
5135   // We update the eden sizes here, when the region is retired,
5136   // instead of when it's allocated, since this is the point that its
5137   // used space has been recored in _summary_bytes_used.
5138   g1mm()->update_eden_size();
5139 }
5140 
5141 // Methods for the GC alloc regions
5142 
5143 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5144   if (dest.is_old()) {
5145     return true;
5146   } else {
5147     return survivor_regions_count() < g1_policy()->max_survivor_regions();
5148   }
5149 }
5150 
5151 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5152   assert(FreeList_lock->owned_by_self(), "pre-condition");
5153 
5154   if (!has_more_regions(dest)) {
5155     return NULL;
5156   }
5157 
5158   const bool is_survivor = dest.is_young();
5159 
5160   HeapRegion* new_alloc_region = new_region(word_size,
5161                                             !is_survivor,
5162                                             true /* do_expand */);
5163   if (new_alloc_region != NULL) {
5164     // We really only need to do this for old regions given that we
5165     // should never scan survivors. But it doesn't hurt to do it
5166     // for survivors too.
5167     new_alloc_region->record_timestamp();
5168     if (is_survivor) {
5169       new_alloc_region->set_survivor();
5170       _survivor.add(new_alloc_region);
5171       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5172     } else {
5173       new_alloc_region->set_old();
5174       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5175     }
5176     _hr_printer.alloc(new_alloc_region);
5177     bool during_im = collector_state()->during_initial_mark_pause();
5178     new_alloc_region->note_start_of_copying(during_im);
5179     return new_alloc_region;
5180   }
5181   return NULL;
5182 }
5183 
5184 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5185                                              size_t allocated_bytes,
5186                                              InCSetState dest) {
5187   bool during_im = collector_state()->during_initial_mark_pause();
5188   alloc_region->note_end_of_copying(during_im);
5189   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5190   if (dest.is_old()) {
5191     _old_set.add(alloc_region);
5192   }
5193   _hr_printer.retire(alloc_region);
5194 }
5195 
5196 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5197   bool expanded = false;
5198   uint index = _hrm.find_highest_free(&expanded);
5199 
5200   if (index != G1_NO_HRM_INDEX) {
5201     if (expanded) {
5202       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5203                                 HeapRegion::GrainWords * HeapWordSize);
5204     }
5205     _hrm.allocate_free_regions_starting_at(index, 1);
5206     return region_at(index);
5207   }
5208   return NULL;
5209 }
5210 
5211 // Optimized nmethod scanning
5212 
5213 class RegisterNMethodOopClosure: public OopClosure {
5214   G1CollectedHeap* _g1h;
5215   nmethod* _nm;
5216 
5217   template <class T> void do_oop_work(T* p) {
5218     T heap_oop = oopDesc::load_heap_oop(p);
5219     if (!oopDesc::is_null(heap_oop)) {
5220       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5221       HeapRegion* hr = _g1h->heap_region_containing(obj);
5222       assert(!hr->is_continues_humongous(),
5223              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5224              " starting at " HR_FORMAT,
5225              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5226 
5227       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5228       hr->add_strong_code_root_locked(_nm);
5229     }
5230   }
5231 
5232 public:
5233   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5234     _g1h(g1h), _nm(nm) {}
5235 
5236   void do_oop(oop* p)       { do_oop_work(p); }
5237   void do_oop(narrowOop* p) { do_oop_work(p); }
5238 };
5239 
5240 class UnregisterNMethodOopClosure: public OopClosure {
5241   G1CollectedHeap* _g1h;
5242   nmethod* _nm;
5243 
5244   template <class T> void do_oop_work(T* p) {
5245     T heap_oop = oopDesc::load_heap_oop(p);
5246     if (!oopDesc::is_null(heap_oop)) {
5247       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5248       HeapRegion* hr = _g1h->heap_region_containing(obj);
5249       assert(!hr->is_continues_humongous(),
5250              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5251              " starting at " HR_FORMAT,
5252              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5253 
5254       hr->remove_strong_code_root(_nm);
5255     }
5256   }
5257 
5258 public:
5259   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5260     _g1h(g1h), _nm(nm) {}
5261 
5262   void do_oop(oop* p)       { do_oop_work(p); }
5263   void do_oop(narrowOop* p) { do_oop_work(p); }
5264 };
5265 
5266 // Returns true if the reference points to an object that
5267 // can move in an incremental collection.
5268 bool G1CollectedHeap::is_scavengable(oop obj) {
5269   HeapRegion* hr = heap_region_containing(obj);
5270   return !hr->is_pinned();
5271 }
5272 
5273 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5274   guarantee(nm != NULL, "sanity");
5275   RegisterNMethodOopClosure reg_cl(this, nm);
5276   nm->oops_do(&reg_cl);
5277 }
5278 
5279 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5280   guarantee(nm != NULL, "sanity");
5281   UnregisterNMethodOopClosure reg_cl(this, nm);
5282   nm->oops_do(&reg_cl, true);
5283 }
5284 
5285 void G1CollectedHeap::purge_code_root_memory() {
5286   double purge_start = os::elapsedTime();
5287   G1CodeRootSet::purge();
5288   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5289   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5290 }
5291 
5292 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5293   G1CollectedHeap* _g1h;
5294 
5295 public:
5296   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5297     _g1h(g1h) {}
5298 
5299   void do_code_blob(CodeBlob* cb) {
5300     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5301     if (nm == NULL) {
5302       return;
5303     }
5304 
5305     if (ScavengeRootsInCode) {
5306       _g1h->register_nmethod(nm);
5307     }
5308   }
5309 };
5310 
5311 void G1CollectedHeap::rebuild_strong_code_roots() {
5312   RebuildStrongCodeRootClosure blob_cl(this);
5313   CodeCache::blobs_do(&blob_cl);
5314 }
5315 
5316 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5317   GrowableArray<GCMemoryManager*> memory_managers(2);
5318   memory_managers.append(&_memory_manager);
5319   memory_managers.append(&_full_gc_memory_manager);
5320   return memory_managers;
5321 }
5322 
5323 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5324   GrowableArray<MemoryPool*> memory_pools(3);
5325   memory_pools.append(_eden_pool);
5326   memory_pools.append(_survivor_pool);
5327   memory_pools.append(_old_pool);
5328   return memory_pools;
5329 }