1 /*
   2  * Copyright (c) 2001, 2015, 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/concurrentG1Refine.hpp"
  33 #include "gc/g1/concurrentG1RefineThread.hpp"
  34 #include "gc/g1/concurrentMarkThread.inline.hpp"
  35 #include "gc/g1/g1Allocator.inline.hpp"
  36 #include "gc/g1/g1CollectedHeap.inline.hpp"
  37 #include "gc/g1/g1CollectorPolicy.hpp"
  38 #include "gc/g1/g1CollectorState.hpp"
  39 #include "gc/g1/g1EvacStats.inline.hpp"
  40 #include "gc/g1/g1GCPhaseTimes.hpp"
  41 #include "gc/g1/g1MarkSweep.hpp"
  42 #include "gc/g1/g1OopClosures.inline.hpp"
  43 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  44 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  45 #include "gc/g1/g1RemSet.inline.hpp"
  46 #include "gc/g1/g1RootClosures.hpp"
  47 #include "gc/g1/g1RootProcessor.hpp"
  48 #include "gc/g1/g1StringDedup.hpp"
  49 #include "gc/g1/g1YCTypes.hpp"
  50 #include "gc/g1/heapRegion.inline.hpp"
  51 #include "gc/g1/heapRegionRemSet.hpp"
  52 #include "gc/g1/heapRegionSet.inline.hpp"
  53 #include "gc/g1/suspendibleThreadSet.hpp"
  54 #include "gc/g1/vm_operations_g1.hpp"
  55 #include "gc/shared/gcHeapSummary.hpp"
  56 #include "gc/shared/gcId.hpp"
  57 #include "gc/shared/gcLocker.inline.hpp"
  58 #include "gc/shared/gcTimer.hpp"
  59 #include "gc/shared/gcTrace.hpp"
  60 #include "gc/shared/gcTraceTime.inline.hpp"
  61 #include "gc/shared/generationSpec.hpp"
  62 #include "gc/shared/isGCActiveMark.hpp"
  63 #include "gc/shared/referenceProcessor.hpp"
  64 #include "gc/shared/taskqueue.inline.hpp"
  65 #include "logging/log.hpp"
  66 #include "memory/allocation.hpp"
  67 #include "memory/iterator.hpp"
  68 #include "oops/oop.inline.hpp"
  69 #include "runtime/atomic.inline.hpp"
  70 #include "runtime/init.hpp"
  71 #include "runtime/orderAccess.inline.hpp"
  72 #include "runtime/vmThread.hpp"
  73 #include "utilities/globalDefinitions.hpp"
  74 #include "utilities/stack.inline.hpp"
  75 
  76 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  77 
  78 // INVARIANTS/NOTES
  79 //
  80 // All allocation activity covered by the G1CollectedHeap interface is
  81 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  82 // and allocate_new_tlab, which are the "entry" points to the
  83 // allocation code from the rest of the JVM.  (Note that this does not
  84 // apply to TLAB allocation, which is not part of this interface: it
  85 // is done by clients of this interface.)
  86 
  87 // Local to this file.
  88 
  89 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  90   bool _concurrent;
  91 public:
  92   RefineCardTableEntryClosure() : _concurrent(true) { }
  93 
  94   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
  95     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
  96     // This path is executed by the concurrent refine or mutator threads,
  97     // concurrently, and so we do not care if card_ptr contains references
  98     // that point into the collection set.
  99     assert(!oops_into_cset, "should be");
 100 
 101     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 102       // Caller will actually yield.
 103       return false;
 104     }
 105     // Otherwise, we finished successfully; return true.
 106     return true;
 107   }
 108 
 109   void set_concurrent(bool b) { _concurrent = b; }
 110 };
 111 
 112 
 113 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 114  private:
 115   size_t _num_dirtied;
 116   G1CollectedHeap* _g1h;
 117   G1SATBCardTableLoggingModRefBS* _g1_bs;
 118 
 119   HeapRegion* region_for_card(jbyte* card_ptr) const {
 120     return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
 121   }
 122 
 123   bool will_become_free(HeapRegion* hr) const {
 124     // A region will be freed by free_collection_set if the region is in the
 125     // collection set and has not had an evacuation failure.
 126     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 127   }
 128 
 129  public:
 130   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 131     _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
 132 
 133   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 134     HeapRegion* hr = region_for_card(card_ptr);
 135 
 136     // Should only dirty cards in regions that won't be freed.
 137     if (!will_become_free(hr)) {
 138       *card_ptr = CardTableModRefBS::dirty_card_val();
 139       _num_dirtied++;
 140     }
 141 
 142     return true;
 143   }
 144 
 145   size_t num_dirtied()   const { return _num_dirtied; }
 146 };
 147 
 148 
 149 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 150   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 151 }
 152 
 153 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 154   // The from card cache is not the memory that is actually committed. So we cannot
 155   // take advantage of the zero_filled parameter.
 156   reset_from_card_cache(start_idx, num_regions);
 157 }
 158 
 159 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 160 {
 161   // Claim the right to put the region on the dirty cards region list
 162   // by installing a self pointer.
 163   HeapRegion* next = hr->get_next_dirty_cards_region();
 164   if (next == NULL) {
 165     HeapRegion* res = (HeapRegion*)
 166       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 167                           NULL);
 168     if (res == NULL) {
 169       HeapRegion* head;
 170       do {
 171         // Put the region to the dirty cards region list.
 172         head = _dirty_cards_region_list;
 173         next = (HeapRegion*)
 174           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 175         if (next == head) {
 176           assert(hr->get_next_dirty_cards_region() == hr,
 177                  "hr->get_next_dirty_cards_region() != hr");
 178           if (next == NULL) {
 179             // The last region in the list points to itself.
 180             hr->set_next_dirty_cards_region(hr);
 181           } else {
 182             hr->set_next_dirty_cards_region(next);
 183           }
 184         }
 185       } while (next != head);
 186     }
 187   }
 188 }
 189 
 190 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 191 {
 192   HeapRegion* head;
 193   HeapRegion* hr;
 194   do {
 195     head = _dirty_cards_region_list;
 196     if (head == NULL) {
 197       return NULL;
 198     }
 199     HeapRegion* new_head = head->get_next_dirty_cards_region();
 200     if (head == new_head) {
 201       // The last region.
 202       new_head = NULL;
 203     }
 204     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 205                                           head);
 206   } while (hr != head);
 207   assert(hr != NULL, "invariant");
 208   hr->set_next_dirty_cards_region(NULL);
 209   return hr;
 210 }
 211 
 212 // Returns true if the reference points to an object that
 213 // can move in an incremental collection.
 214 bool G1CollectedHeap::is_scavengable(const void* p) {
 215   HeapRegion* hr = heap_region_containing(p);
 216   return !hr->is_pinned();
 217 }
 218 
 219 // Private methods.
 220 
 221 HeapRegion*
 222 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 223   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 224   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 225     if (!_secondary_free_list.is_empty()) {
 226       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 227                                       "secondary_free_list has %u entries",
 228                                       _secondary_free_list.length());
 229       // It looks as if there are free regions available on the
 230       // secondary_free_list. Let's move them to the free_list and try
 231       // again to allocate from it.
 232       append_secondary_free_list();
 233 
 234       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 235              "empty we should have moved at least one entry to the free_list");
 236       HeapRegion* res = _hrm.allocate_free_region(is_old);
 237       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 238                                       "allocated " HR_FORMAT " from secondary_free_list",
 239                                       HR_FORMAT_PARAMS(res));
 240       return res;
 241     }
 242 
 243     // Wait here until we get notified either when (a) there are no
 244     // more free regions coming or (b) some regions have been moved on
 245     // the secondary_free_list.
 246     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 247   }
 248 
 249   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 250                                   "could not allocate from secondary_free_list");
 251   return NULL;
 252 }
 253 
 254 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 255   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 256          "the only time we use this to allocate a humongous region is "
 257          "when we are allocating a single humongous region");
 258 
 259   HeapRegion* res;
 260   if (G1StressConcRegionFreeing) {
 261     if (!_secondary_free_list.is_empty()) {
 262       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 263                                       "forced to look at the secondary_free_list");
 264       res = new_region_try_secondary_free_list(is_old);
 265       if (res != NULL) {
 266         return res;
 267       }
 268     }
 269   }
 270 
 271   res = _hrm.allocate_free_region(is_old);
 272 
 273   if (res == NULL) {
 274     log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 275                                     "res == NULL, trying the secondary_free_list");
 276     res = new_region_try_secondary_free_list(is_old);
 277   }
 278   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 279     // Currently, only attempts to allocate GC alloc regions set
 280     // do_expand to true. So, we should only reach here during a
 281     // safepoint. If this assumption changes we might have to
 282     // reconsider the use of _expand_heap_after_alloc_failure.
 283     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 284 
 285     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 286                               word_size * HeapWordSize);
 287 
 288     if (expand(word_size * HeapWordSize)) {
 289       // Given that expand() succeeded in expanding the heap, and we
 290       // always expand the heap by an amount aligned to the heap
 291       // region size, the free list should in theory not be empty.
 292       // In either case allocate_free_region() will check for NULL.
 293       res = _hrm.allocate_free_region(is_old);
 294     } else {
 295       _expand_heap_after_alloc_failure = false;
 296     }
 297   }
 298   return res;
 299 }
 300 
 301 HeapWord*
 302 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 303                                                            uint num_regions,
 304                                                            size_t word_size,
 305                                                            AllocationContext_t context) {
 306   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 307   assert(is_humongous(word_size), "word_size should be humongous");
 308   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 309 
 310   // Index of last region in the series.
 311   uint last = first + num_regions - 1;
 312 
 313   // We need to initialize the region(s) we just discovered. This is
 314   // a bit tricky given that it can happen concurrently with
 315   // refinement threads refining cards on these regions and
 316   // potentially wanting to refine the BOT as they are scanning
 317   // those cards (this can happen shortly after a cleanup; see CR
 318   // 6991377). So we have to set up the region(s) carefully and in
 319   // a specific order.
 320 
 321   // The word size sum of all the regions we will allocate.
 322   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 323   assert(word_size <= word_size_sum, "sanity");
 324 
 325   // This will be the "starts humongous" region.
 326   HeapRegion* first_hr = region_at(first);
 327   // The header of the new object will be placed at the bottom of
 328   // the first region.
 329   HeapWord* new_obj = first_hr->bottom();
 330   // This will be the new top of the new object.
 331   HeapWord* obj_top = new_obj + word_size;
 332 
 333   // First, we need to zero the header of the space that we will be
 334   // allocating. When we update top further down, some refinement
 335   // threads might try to scan the region. By zeroing the header we
 336   // ensure that any thread that will try to scan the region will
 337   // come across the zero klass word and bail out.
 338   //
 339   // NOTE: It would not have been correct to have used
 340   // CollectedHeap::fill_with_object() and make the space look like
 341   // an int array. The thread that is doing the allocation will
 342   // later update the object header to a potentially different array
 343   // type and, for a very short period of time, the klass and length
 344   // fields will be inconsistent. This could cause a refinement
 345   // thread to calculate the object size incorrectly.
 346   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 347 
 348   // How many words we use for filler objects.
 349   size_t word_fill_size = word_size_sum - word_size;
 350 
 351   // How many words memory we "waste" which cannot hold a filler object.
 352   size_t words_not_fillable = 0;
 353 
 354   if (word_fill_size >= min_fill_size()) {
 355     fill_with_objects(obj_top, word_fill_size);
 356   } else if (word_fill_size > 0) {
 357     // We have space to fill, but we cannot fit an object there.
 358     words_not_fillable = word_fill_size;
 359     word_fill_size = 0;
 360   }
 361 
 362   // We will set up the first region as "starts humongous". This
 363   // will also update the BOT covering all the regions to reflect
 364   // that there is a single object that starts at the bottom of the
 365   // first region.
 366   first_hr->set_starts_humongous(obj_top, word_fill_size);
 367   first_hr->set_allocation_context(context);
 368   // Then, if there are any, we will set up the "continues
 369   // humongous" regions.
 370   HeapRegion* hr = NULL;
 371   for (uint i = first + 1; i <= last; ++i) {
 372     hr = region_at(i);
 373     hr->set_continues_humongous(first_hr);
 374     hr->set_allocation_context(context);
 375   }
 376 
 377   // Up to this point no concurrent thread would have been able to
 378   // do any scanning on any region in this series. All the top
 379   // fields still point to bottom, so the intersection between
 380   // [bottom,top] and [card_start,card_end] will be empty. Before we
 381   // update the top fields, we'll do a storestore to make sure that
 382   // no thread sees the update to top before the zeroing of the
 383   // object header and the BOT initialization.
 384   OrderAccess::storestore();
 385 
 386   // Now, we will update the top fields of the "continues humongous"
 387   // regions except the last one.
 388   for (uint i = first; i < last; ++i) {
 389     hr = region_at(i);
 390     hr->set_top(hr->end());
 391   }
 392 
 393   hr = region_at(last);
 394   // If we cannot fit a filler object, we must set top to the end
 395   // of the humongous object, otherwise we cannot iterate the heap
 396   // and the BOT will not be complete.
 397   hr->set_top(hr->end() - words_not_fillable);
 398 
 399   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 400          "obj_top should be in last region");
 401 
 402   check_bitmaps("Humongous Region Allocation", first_hr);
 403 
 404   assert(words_not_fillable == 0 ||
 405          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 406          "Miscalculation in humongous allocation");
 407 
 408   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 409 
 410   for (uint i = first; i <= last; ++i) {
 411     hr = region_at(i);
 412     _humongous_set.add(hr);
 413     _hr_printer.alloc(hr);
 414   }
 415 
 416   return new_obj;
 417 }
 418 
 419 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 420   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 421   return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 422 }
 423 
 424 // If could fit into free regions w/o expansion, try.
 425 // Otherwise, if can expand, do so.
 426 // Otherwise, if using ex regions might help, try with ex given back.
 427 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 428   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 429 
 430   verify_region_sets_optional();
 431 
 432   uint first = G1_NO_HRM_INDEX;
 433   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 434 
 435   if (obj_regions == 1) {
 436     // Only one region to allocate, try to use a fast path by directly allocating
 437     // from the free lists. Do not try to expand here, we will potentially do that
 438     // later.
 439     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 440     if (hr != NULL) {
 441       first = hr->hrm_index();
 442     }
 443   } else {
 444     // We can't allocate humongous regions spanning more than one region while
 445     // cleanupComplete() is running, since some of the regions we find to be
 446     // empty might not yet be added to the free list. It is not straightforward
 447     // to know in which list they are on so that we can remove them. We only
 448     // need to do this if we need to allocate more than one region to satisfy the
 449     // current humongous allocation request. If we are only allocating one region
 450     // we use the one-region region allocation code (see above), that already
 451     // potentially waits for regions from the secondary free list.
 452     wait_while_free_regions_coming();
 453     append_secondary_free_list_if_not_empty_with_lock();
 454 
 455     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 456     // are lucky enough to find some.
 457     first = _hrm.find_contiguous_only_empty(obj_regions);
 458     if (first != G1_NO_HRM_INDEX) {
 459       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 460     }
 461   }
 462 
 463   if (first == G1_NO_HRM_INDEX) {
 464     // Policy: We could not find enough regions for the humongous object in the
 465     // free list. Look through the heap to find a mix of free and uncommitted regions.
 466     // If so, try expansion.
 467     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 468     if (first != G1_NO_HRM_INDEX) {
 469       // We found something. Make sure these regions are committed, i.e. expand
 470       // the heap. Alternatively we could do a defragmentation GC.
 471       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 472                                     word_size * HeapWordSize);
 473 
 474 
 475       _hrm.expand_at(first, obj_regions);
 476       g1_policy()->record_new_heap_size(num_regions());
 477 
 478 #ifdef ASSERT
 479       for (uint i = first; i < first + obj_regions; ++i) {
 480         HeapRegion* hr = region_at(i);
 481         assert(hr->is_free(), "sanity");
 482         assert(hr->is_empty(), "sanity");
 483         assert(is_on_master_free_list(hr), "sanity");
 484       }
 485 #endif
 486       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 487     } else {
 488       // Policy: Potentially trigger a defragmentation GC.
 489     }
 490   }
 491 
 492   HeapWord* result = NULL;
 493   if (first != G1_NO_HRM_INDEX) {
 494     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 495                                                        word_size, context);
 496     assert(result != NULL, "it should always return a valid result");
 497 
 498     // A successful humongous object allocation changes the used space
 499     // information of the old generation so we need to recalculate the
 500     // sizes and update the jstat counters here.
 501     g1mm()->update_sizes();
 502   }
 503 
 504   verify_region_sets_optional();
 505 
 506   return result;
 507 }
 508 
 509 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 510   assert_heap_not_locked_and_not_at_safepoint();
 511   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 512 
 513   uint dummy_gc_count_before;
 514   uint dummy_gclocker_retry_count = 0;
 515   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 516 }
 517 
 518 HeapWord*
 519 G1CollectedHeap::mem_allocate(size_t word_size,
 520                               bool*  gc_overhead_limit_was_exceeded) {
 521   assert_heap_not_locked_and_not_at_safepoint();
 522 
 523   // Loop until the allocation is satisfied, or unsatisfied after GC.
 524   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 525     uint gc_count_before;
 526 
 527     HeapWord* result = NULL;
 528     if (!is_humongous(word_size)) {
 529       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 530     } else {
 531       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 532     }
 533     if (result != NULL) {
 534       return result;
 535     }
 536 
 537     // Create the garbage collection operation...
 538     VM_G1CollectForAllocation op(gc_count_before, word_size);
 539     op.set_allocation_context(AllocationContext::current());
 540 
 541     // ...and get the VM thread to execute it.
 542     VMThread::execute(&op);
 543 
 544     if (op.prologue_succeeded() && op.pause_succeeded()) {
 545       // If the operation was successful we'll return the result even
 546       // if it is NULL. If the allocation attempt failed immediately
 547       // after a Full GC, it's unlikely we'll be able to allocate now.
 548       HeapWord* result = op.result();
 549       if (result != NULL && !is_humongous(word_size)) {
 550         // Allocations that take place on VM operations do not do any
 551         // card dirtying and we have to do it here. We only have to do
 552         // this for non-humongous allocations, though.
 553         dirty_young_block(result, word_size);
 554       }
 555       return result;
 556     } else {
 557       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 558         return NULL;
 559       }
 560       assert(op.result() == NULL,
 561              "the result should be NULL if the VM op did not succeed");
 562     }
 563 
 564     // Give a warning if we seem to be looping forever.
 565     if ((QueuedAllocationWarningCount > 0) &&
 566         (try_count % QueuedAllocationWarningCount == 0)) {
 567       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 568     }
 569   }
 570 
 571   ShouldNotReachHere();
 572   return NULL;
 573 }
 574 
 575 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 576                                                    AllocationContext_t context,
 577                                                    uint* gc_count_before_ret,
 578                                                    uint* gclocker_retry_count_ret) {
 579   // Make sure you read the note in attempt_allocation_humongous().
 580 
 581   assert_heap_not_locked_and_not_at_safepoint();
 582   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 583          "be called for humongous allocation requests");
 584 
 585   // We should only get here after the first-level allocation attempt
 586   // (attempt_allocation()) failed to allocate.
 587 
 588   // We will loop until a) we manage to successfully perform the
 589   // allocation or b) we successfully schedule a collection which
 590   // fails to perform the allocation. b) is the only case when we'll
 591   // return NULL.
 592   HeapWord* result = NULL;
 593   for (int try_count = 1; /* we'll return */; try_count += 1) {
 594     bool should_try_gc;
 595     uint gc_count_before;
 596 
 597     {
 598       MutexLockerEx x(Heap_lock);
 599       result = _allocator->attempt_allocation_locked(word_size, context);
 600       if (result != NULL) {
 601         return result;
 602       }
 603 
 604       if (GCLocker::is_active_and_needs_gc()) {
 605         if (g1_policy()->can_expand_young_list()) {
 606           // No need for an ergo verbose message here,
 607           // can_expand_young_list() does this when it returns true.
 608           result = _allocator->attempt_allocation_force(word_size, context);
 609           if (result != NULL) {
 610             return result;
 611           }
 612         }
 613         should_try_gc = false;
 614       } else {
 615         // The GCLocker may not be active but the GCLocker initiated
 616         // GC may not yet have been performed (GCLocker::needs_gc()
 617         // returns true). In this case we do not try this GC and
 618         // wait until the GCLocker initiated GC is performed, and
 619         // then retry the allocation.
 620         if (GCLocker::needs_gc()) {
 621           should_try_gc = false;
 622         } else {
 623           // Read the GC count while still holding the Heap_lock.
 624           gc_count_before = total_collections();
 625           should_try_gc = true;
 626         }
 627       }
 628     }
 629 
 630     if (should_try_gc) {
 631       bool succeeded;
 632       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 633                                    GCCause::_g1_inc_collection_pause);
 634       if (result != NULL) {
 635         assert(succeeded, "only way to get back a non-NULL result");
 636         return result;
 637       }
 638 
 639       if (succeeded) {
 640         // If we get here we successfully scheduled a collection which
 641         // failed to allocate. No point in trying to allocate
 642         // further. We'll just return NULL.
 643         MutexLockerEx x(Heap_lock);
 644         *gc_count_before_ret = total_collections();
 645         return NULL;
 646       }
 647     } else {
 648       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 649         MutexLockerEx x(Heap_lock);
 650         *gc_count_before_ret = total_collections();
 651         return NULL;
 652       }
 653       // The GCLocker is either active or the GCLocker initiated
 654       // GC has not yet been performed. Stall until it is and
 655       // then retry the allocation.
 656       GCLocker::stall_until_clear();
 657       (*gclocker_retry_count_ret) += 1;
 658     }
 659 
 660     // We can reach here if we were unsuccessful in scheduling a
 661     // collection (because another thread beat us to it) or if we were
 662     // stalled due to the GC locker. In either can we should retry the
 663     // allocation attempt in case another thread successfully
 664     // performed a collection and reclaimed enough space. We do the
 665     // first attempt (without holding the Heap_lock) here and the
 666     // follow-on attempt will be at the start of the next loop
 667     // iteration (after taking the Heap_lock).
 668     result = _allocator->attempt_allocation(word_size, context);
 669     if (result != NULL) {
 670       return result;
 671     }
 672 
 673     // Give a warning if we seem to be looping forever.
 674     if ((QueuedAllocationWarningCount > 0) &&
 675         (try_count % QueuedAllocationWarningCount == 0)) {
 676       warning("G1CollectedHeap::attempt_allocation_slow() "
 677               "retries %d times", try_count);
 678     }
 679   }
 680 
 681   ShouldNotReachHere();
 682   return NULL;
 683 }
 684 
 685 void G1CollectedHeap::begin_archive_alloc_range() {
 686   assert_at_safepoint(true /* should_be_vm_thread */);
 687   if (_archive_allocator == NULL) {
 688     _archive_allocator = G1ArchiveAllocator::create_allocator(this);
 689   }
 690 }
 691 
 692 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 693   // Allocations in archive regions cannot be of a size that would be considered
 694   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 695   // may be different at archive-restore time.
 696   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 697 }
 698 
 699 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 700   assert_at_safepoint(true /* should_be_vm_thread */);
 701   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 702   if (is_archive_alloc_too_large(word_size)) {
 703     return NULL;
 704   }
 705   return _archive_allocator->archive_mem_allocate(word_size);
 706 }
 707 
 708 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 709                                               size_t end_alignment_in_bytes) {
 710   assert_at_safepoint(true /* should_be_vm_thread */);
 711   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 712 
 713   // Call complete_archive to do the real work, filling in the MemRegion
 714   // array with the archive regions.
 715   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 716   delete _archive_allocator;
 717   _archive_allocator = NULL;
 718 }
 719 
 720 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 721   assert(ranges != NULL, "MemRegion array NULL");
 722   assert(count != 0, "No MemRegions provided");
 723   MemRegion reserved = _hrm.reserved();
 724   for (size_t i = 0; i < count; i++) {
 725     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 726       return false;
 727     }
 728   }
 729   return true;
 730 }
 731 
 732 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
 733   assert(!is_init_completed(), "Expect to be called at JVM init time");
 734   assert(ranges != NULL, "MemRegion array NULL");
 735   assert(count != 0, "No MemRegions provided");
 736   MutexLockerEx x(Heap_lock);
 737 
 738   MemRegion reserved = _hrm.reserved();
 739   HeapWord* prev_last_addr = NULL;
 740   HeapRegion* prev_last_region = NULL;
 741 
 742   // Temporarily disable pretouching of heap pages. This interface is used
 743   // when mmap'ing archived heap data in, so pre-touching is wasted.
 744   FlagSetting fs(AlwaysPreTouch, false);
 745 
 746   // Enable archive object checking in G1MarkSweep. We have to let it know
 747   // about each archive range, so that objects in those ranges aren't marked.
 748   G1MarkSweep::enable_archive_object_check();
 749 
 750   // For each specified MemRegion range, allocate the corresponding G1
 751   // regions and mark them as archive regions. We expect the ranges in
 752   // ascending starting address order, without overlap.
 753   for (size_t i = 0; i < count; i++) {
 754     MemRegion curr_range = ranges[i];
 755     HeapWord* start_address = curr_range.start();
 756     size_t word_size = curr_range.word_size();
 757     HeapWord* last_address = curr_range.last();
 758     size_t commits = 0;
 759 
 760     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 761               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 762               p2i(start_address), p2i(last_address));
 763     guarantee(start_address > prev_last_addr,
 764               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 765               p2i(start_address), p2i(prev_last_addr));
 766     prev_last_addr = last_address;
 767 
 768     // Check for ranges that start in the same G1 region in which the previous
 769     // range ended, and adjust the start address so we don't try to allocate
 770     // the same region again. If the current range is entirely within that
 771     // region, skip it, just adjusting the recorded top.
 772     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 773     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 774       start_address = start_region->end();
 775       if (start_address > last_address) {
 776         increase_used(word_size * HeapWordSize);
 777         start_region->set_top(last_address + 1);
 778         continue;
 779       }
 780       start_region->set_top(start_address);
 781       curr_range = MemRegion(start_address, last_address + 1);
 782       start_region = _hrm.addr_to_region(start_address);
 783     }
 784 
 785     // Perform the actual region allocation, exiting if it fails.
 786     // Then note how much new space we have allocated.
 787     if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
 788       return false;
 789     }
 790     increase_used(word_size * HeapWordSize);
 791     if (commits != 0) {
 792       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 793                                 HeapRegion::GrainWords * HeapWordSize * commits);
 794 
 795     }
 796 
 797     // Mark each G1 region touched by the range as archive, add it to the old set,
 798     // and set the allocation context and top.
 799     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 800     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 801     prev_last_region = last_region;
 802 
 803     while (curr_region != NULL) {
 804       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 805              "Region already in use (index %u)", curr_region->hrm_index());
 806       curr_region->set_allocation_context(AllocationContext::system());
 807       curr_region->set_archive();
 808       _hr_printer.alloc(curr_region);
 809       _old_set.add(curr_region);
 810       if (curr_region != last_region) {
 811         curr_region->set_top(curr_region->end());
 812         curr_region = _hrm.next_region_in_heap(curr_region);
 813       } else {
 814         curr_region->set_top(last_address + 1);
 815         curr_region = NULL;
 816       }
 817     }
 818 
 819     // Notify mark-sweep of the archive range.
 820     G1MarkSweep::set_range_archive(curr_range, true);
 821   }
 822   return true;
 823 }
 824 
 825 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 826   assert(!is_init_completed(), "Expect to be called at JVM init time");
 827   assert(ranges != NULL, "MemRegion array NULL");
 828   assert(count != 0, "No MemRegions provided");
 829   MemRegion reserved = _hrm.reserved();
 830   HeapWord *prev_last_addr = NULL;
 831   HeapRegion* prev_last_region = NULL;
 832 
 833   // For each MemRegion, create filler objects, if needed, in the G1 regions
 834   // that contain the address range. The address range actually within the
 835   // MemRegion will not be modified. That is assumed to have been initialized
 836   // elsewhere, probably via an mmap of archived heap data.
 837   MutexLockerEx x(Heap_lock);
 838   for (size_t i = 0; i < count; i++) {
 839     HeapWord* start_address = ranges[i].start();
 840     HeapWord* last_address = ranges[i].last();
 841 
 842     assert(reserved.contains(start_address) && reserved.contains(last_address),
 843            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 844            p2i(start_address), p2i(last_address));
 845     assert(start_address > prev_last_addr,
 846            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 847            p2i(start_address), p2i(prev_last_addr));
 848 
 849     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 850     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 851     HeapWord* bottom_address = start_region->bottom();
 852 
 853     // Check for a range beginning in the same region in which the
 854     // previous one ended.
 855     if (start_region == prev_last_region) {
 856       bottom_address = prev_last_addr + 1;
 857     }
 858 
 859     // Verify that the regions were all marked as archive regions by
 860     // alloc_archive_regions.
 861     HeapRegion* curr_region = start_region;
 862     while (curr_region != NULL) {
 863       guarantee(curr_region->is_archive(),
 864                 "Expected archive region at index %u", curr_region->hrm_index());
 865       if (curr_region != last_region) {
 866         curr_region = _hrm.next_region_in_heap(curr_region);
 867       } else {
 868         curr_region = NULL;
 869       }
 870     }
 871 
 872     prev_last_addr = last_address;
 873     prev_last_region = last_region;
 874 
 875     // Fill the memory below the allocated range with dummy object(s),
 876     // if the region bottom does not match the range start, or if the previous
 877     // range ended within the same G1 region, and there is a gap.
 878     if (start_address != bottom_address) {
 879       size_t fill_size = pointer_delta(start_address, bottom_address);
 880       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 881       increase_used(fill_size * HeapWordSize);
 882     }
 883   }
 884 }
 885 
 886 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
 887                                                      uint* gc_count_before_ret,
 888                                                      uint* gclocker_retry_count_ret) {
 889   assert_heap_not_locked_and_not_at_safepoint();
 890   assert(!is_humongous(word_size), "attempt_allocation() should not "
 891          "be called for humongous allocation requests");
 892 
 893   AllocationContext_t context = AllocationContext::current();
 894   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 895 
 896   if (result == NULL) {
 897     result = attempt_allocation_slow(word_size,
 898                                      context,
 899                                      gc_count_before_ret,
 900                                      gclocker_retry_count_ret);
 901   }
 902   assert_heap_not_locked();
 903   if (result != NULL) {
 904     dirty_young_block(result, word_size);
 905   }
 906   return result;
 907 }
 908 
 909 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 910   assert(!is_init_completed(), "Expect to be called at JVM init time");
 911   assert(ranges != NULL, "MemRegion array NULL");
 912   assert(count != 0, "No MemRegions provided");
 913   MemRegion reserved = _hrm.reserved();
 914   HeapWord* prev_last_addr = NULL;
 915   HeapRegion* prev_last_region = NULL;
 916   size_t size_used = 0;
 917   size_t uncommitted_regions = 0;
 918 
 919   // For each Memregion, free the G1 regions that constitute it, and
 920   // notify mark-sweep that the range is no longer to be considered 'archive.'
 921   MutexLockerEx x(Heap_lock);
 922   for (size_t i = 0; i < count; i++) {
 923     HeapWord* start_address = ranges[i].start();
 924     HeapWord* last_address = ranges[i].last();
 925 
 926     assert(reserved.contains(start_address) && reserved.contains(last_address),
 927            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 928            p2i(start_address), p2i(last_address));
 929     assert(start_address > prev_last_addr,
 930            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 931            p2i(start_address), p2i(prev_last_addr));
 932     size_used += ranges[i].byte_size();
 933     prev_last_addr = last_address;
 934 
 935     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 936     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 937 
 938     // Check for ranges that start in the same G1 region in which the previous
 939     // range ended, and adjust the start address so we don't try to free
 940     // the same region again. If the current range is entirely within that
 941     // region, skip it.
 942     if (start_region == prev_last_region) {
 943       start_address = start_region->end();
 944       if (start_address > last_address) {
 945         continue;
 946       }
 947       start_region = _hrm.addr_to_region(start_address);
 948     }
 949     prev_last_region = last_region;
 950 
 951     // After verifying that each region was marked as an archive region by
 952     // alloc_archive_regions, set it free and empty and uncommit it.
 953     HeapRegion* curr_region = start_region;
 954     while (curr_region != NULL) {
 955       guarantee(curr_region->is_archive(),
 956                 "Expected archive region at index %u", curr_region->hrm_index());
 957       uint curr_index = curr_region->hrm_index();
 958       _old_set.remove(curr_region);
 959       curr_region->set_free();
 960       curr_region->set_top(curr_region->bottom());
 961       if (curr_region != last_region) {
 962         curr_region = _hrm.next_region_in_heap(curr_region);
 963       } else {
 964         curr_region = NULL;
 965       }
 966       _hrm.shrink_at(curr_index, 1);
 967       uncommitted_regions++;
 968     }
 969 
 970     // Notify mark-sweep that this is no longer an archive range.
 971     G1MarkSweep::set_range_archive(ranges[i], false);
 972   }
 973 
 974   if (uncommitted_regions != 0) {
 975     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 976                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 977   }
 978   decrease_used(size_used);
 979 }
 980 
 981 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 982                                                         uint* gc_count_before_ret,
 983                                                         uint* gclocker_retry_count_ret) {
 984   // The structure of this method has a lot of similarities to
 985   // attempt_allocation_slow(). The reason these two were not merged
 986   // into a single one is that such a method would require several "if
 987   // allocation is not humongous do this, otherwise do that"
 988   // conditional paths which would obscure its flow. In fact, an early
 989   // version of this code did use a unified method which was harder to
 990   // follow and, as a result, it had subtle bugs that were hard to
 991   // track down. So keeping these two methods separate allows each to
 992   // be more readable. It will be good to keep these two in sync as
 993   // much as possible.
 994 
 995   assert_heap_not_locked_and_not_at_safepoint();
 996   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 997          "should only be called for humongous allocations");
 998 
 999   // Humongous objects can exhaust the heap quickly, so we should check if we
1000   // need to start a marking cycle at each humongous object allocation. We do
1001   // the check before we do the actual allocation. The reason for doing it
1002   // before the allocation is that we avoid having to keep track of the newly
1003   // allocated memory while we do a GC.
1004   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1005                                            word_size)) {
1006     collect(GCCause::_g1_humongous_allocation);
1007   }
1008 
1009   // We will loop until a) we manage to successfully perform the
1010   // allocation or b) we successfully schedule a collection which
1011   // fails to perform the allocation. b) is the only case when we'll
1012   // return NULL.
1013   HeapWord* result = NULL;
1014   for (int try_count = 1; /* we'll return */; try_count += 1) {
1015     bool should_try_gc;
1016     uint gc_count_before;
1017 
1018     {
1019       MutexLockerEx x(Heap_lock);
1020 
1021       // Given that humongous objects are not allocated in young
1022       // regions, we'll first try to do the allocation without doing a
1023       // collection hoping that there's enough space in the heap.
1024       result = humongous_obj_allocate(word_size, AllocationContext::current());
1025       if (result != NULL) {
1026         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1027         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1028         return result;
1029       }
1030 
1031       if (GCLocker::is_active_and_needs_gc()) {
1032         should_try_gc = false;
1033       } else {
1034          // The GCLocker may not be active but the GCLocker initiated
1035         // GC may not yet have been performed (GCLocker::needs_gc()
1036         // returns true). In this case we do not try this GC and
1037         // wait until the GCLocker initiated GC is performed, and
1038         // then retry the allocation.
1039         if (GCLocker::needs_gc()) {
1040           should_try_gc = false;
1041         } else {
1042           // Read the GC count while still holding the Heap_lock.
1043           gc_count_before = total_collections();
1044           should_try_gc = true;
1045         }
1046       }
1047     }
1048 
1049     if (should_try_gc) {
1050       // If we failed to allocate the humongous object, we should try to
1051       // do a collection pause (if we're allowed) in case it reclaims
1052       // enough space for the allocation to succeed after the pause.
1053 
1054       bool succeeded;
1055       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1056                                    GCCause::_g1_humongous_allocation);
1057       if (result != NULL) {
1058         assert(succeeded, "only way to get back a non-NULL result");
1059         return result;
1060       }
1061 
1062       if (succeeded) {
1063         // If we get here we successfully scheduled a collection which
1064         // failed to allocate. No point in trying to allocate
1065         // further. We'll just return NULL.
1066         MutexLockerEx x(Heap_lock);
1067         *gc_count_before_ret = total_collections();
1068         return NULL;
1069       }
1070     } else {
1071       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1072         MutexLockerEx x(Heap_lock);
1073         *gc_count_before_ret = total_collections();
1074         return NULL;
1075       }
1076       // The GCLocker is either active or the GCLocker initiated
1077       // GC has not yet been performed. Stall until it is and
1078       // then retry the allocation.
1079       GCLocker::stall_until_clear();
1080       (*gclocker_retry_count_ret) += 1;
1081     }
1082 
1083     // We can reach here if we were unsuccessful in scheduling a
1084     // collection (because another thread beat us to it) or if we were
1085     // stalled due to the GC locker. In either can we should retry the
1086     // allocation attempt in case another thread successfully
1087     // performed a collection and reclaimed enough space.  Give a
1088     // warning if we seem to be looping forever.
1089 
1090     if ((QueuedAllocationWarningCount > 0) &&
1091         (try_count % QueuedAllocationWarningCount == 0)) {
1092       warning("G1CollectedHeap::attempt_allocation_humongous() "
1093               "retries %d times", try_count);
1094     }
1095   }
1096 
1097   ShouldNotReachHere();
1098   return NULL;
1099 }
1100 
1101 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1102                                                            AllocationContext_t context,
1103                                                            bool expect_null_mutator_alloc_region) {
1104   assert_at_safepoint(true /* should_be_vm_thread */);
1105   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1106          "the current alloc region was unexpectedly found to be non-NULL");
1107 
1108   if (!is_humongous(word_size)) {
1109     return _allocator->attempt_allocation_locked(word_size, context);
1110   } else {
1111     HeapWord* result = humongous_obj_allocate(word_size, context);
1112     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1113       collector_state()->set_initiate_conc_mark_if_possible(true);
1114     }
1115     return result;
1116   }
1117 
1118   ShouldNotReachHere();
1119 }
1120 
1121 class PostMCRemSetClearClosure: public HeapRegionClosure {
1122   G1CollectedHeap* _g1h;
1123   ModRefBarrierSet* _mr_bs;
1124 public:
1125   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1126     _g1h(g1h), _mr_bs(mr_bs) {}
1127 
1128   bool doHeapRegion(HeapRegion* r) {
1129     HeapRegionRemSet* hrrs = r->rem_set();
1130 
1131     _g1h->reset_gc_time_stamps(r);
1132 
1133     if (r->is_continues_humongous()) {
1134       // We'll assert that the strong code root list and RSet is empty
1135       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1136       assert(hrrs->occupied() == 0, "RSet should be empty");
1137     } else {
1138       hrrs->clear();
1139     }
1140     // You might think here that we could clear just the cards
1141     // corresponding to the used region.  But no: if we leave a dirty card
1142     // in a region we might allocate into, then it would prevent that card
1143     // from being enqueued, and cause it to be missed.
1144     // Re: the performance cost: we shouldn't be doing full GC anyway!
1145     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1146 
1147     return false;
1148   }
1149 };
1150 
1151 void G1CollectedHeap::clear_rsets_post_compaction() {
1152   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1153   heap_region_iterate(&rs_clear);
1154 }
1155 
1156 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1157   G1CollectedHeap*   _g1h;
1158   UpdateRSOopClosure _cl;
1159 public:
1160   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1161     _cl(g1->g1_rem_set(), worker_i),
1162     _g1h(g1)
1163   { }
1164 
1165   bool doHeapRegion(HeapRegion* r) {
1166     if (!r->is_continues_humongous()) {
1167       _cl.set_from(r);
1168       r->oop_iterate(&_cl);
1169     }
1170     return false;
1171   }
1172 };
1173 
1174 class ParRebuildRSTask: public AbstractGangTask {
1175   G1CollectedHeap* _g1;
1176   HeapRegionClaimer _hrclaimer;
1177 
1178 public:
1179   ParRebuildRSTask(G1CollectedHeap* g1) :
1180       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1181 
1182   void work(uint worker_id) {
1183     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1184     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1185   }
1186 };
1187 
1188 class PostCompactionPrinterClosure: public HeapRegionClosure {
1189 private:
1190   G1HRPrinter* _hr_printer;
1191 public:
1192   bool doHeapRegion(HeapRegion* hr) {
1193     assert(!hr->is_young(), "not expecting to find young regions");
1194     _hr_printer->post_compaction(hr);
1195     return false;
1196   }
1197 
1198   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1199     : _hr_printer(hr_printer) { }
1200 };
1201 
1202 void G1CollectedHeap::print_hrm_post_compaction() {
1203   if (_hr_printer.is_active()) {
1204     PostCompactionPrinterClosure cl(hr_printer());
1205     heap_region_iterate(&cl);
1206   }
1207 
1208 }
1209 
1210 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1211                                          bool clear_all_soft_refs) {
1212   assert_at_safepoint(true /* should_be_vm_thread */);
1213 
1214   if (GCLocker::check_active_before_gc()) {
1215     return false;
1216   }
1217 
1218   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1219   gc_timer->register_gc_start();
1220 
1221   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1222   GCIdMark gc_id_mark;
1223   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1224 
1225   SvcGCMarker sgcm(SvcGCMarker::FULL);
1226   ResourceMark rm;
1227 
1228   print_heap_before_gc();
1229   trace_heap_before_gc(gc_tracer);
1230 
1231   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1232 
1233   verify_region_sets_optional();
1234 
1235   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1236                            collector_policy()->should_clear_all_soft_refs();
1237 
1238   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1239 
1240   {
1241     IsGCActiveMark x;
1242 
1243     // Timing
1244     assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1245     GCTraceCPUTime tcpu;
1246 
1247     {
1248       GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1249       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1250       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1251 
1252       g1_policy()->record_full_collection_start();
1253 
1254       // Note: When we have a more flexible GC logging framework that
1255       // allows us to add optional attributes to a GC log record we
1256       // could consider timing and reporting how long we wait in the
1257       // following two methods.
1258       wait_while_free_regions_coming();
1259       // If we start the compaction before the CM threads finish
1260       // scanning the root regions we might trip them over as we'll
1261       // be moving objects / updating references. So let's wait until
1262       // they are done. By telling them to abort, they should complete
1263       // early.
1264       _cm->root_regions()->abort();
1265       _cm->root_regions()->wait_until_scan_finished();
1266       append_secondary_free_list_if_not_empty_with_lock();
1267 
1268       gc_prologue(true);
1269       increment_total_collections(true /* full gc */);
1270       increment_old_marking_cycles_started();
1271 
1272       assert(used() == recalculate_used(), "Should be equal");
1273 
1274       verify_before_gc();
1275 
1276       check_bitmaps("Full GC Start");
1277       pre_full_gc_dump(gc_timer);
1278 
1279 #if defined(COMPILER2) || INCLUDE_JVMCI
1280       DerivedPointerTable::clear();
1281 #endif
1282 
1283       // Disable discovery and empty the discovered lists
1284       // for the CM ref processor.
1285       ref_processor_cm()->disable_discovery();
1286       ref_processor_cm()->abandon_partial_discovery();
1287       ref_processor_cm()->verify_no_references_recorded();
1288 
1289       // Abandon current iterations of concurrent marking and concurrent
1290       // refinement, if any are in progress. We have to do this before
1291       // wait_until_scan_finished() below.
1292       concurrent_mark()->abort();
1293 
1294       // Make sure we'll choose a new allocation region afterwards.
1295       _allocator->release_mutator_alloc_region();
1296       _allocator->abandon_gc_alloc_regions();
1297       g1_rem_set()->cleanupHRRS();
1298 
1299       // We may have added regions to the current incremental collection
1300       // set between the last GC or pause and now. We need to clear the
1301       // incremental collection set and then start rebuilding it afresh
1302       // after this full GC.
1303       abandon_collection_set(g1_policy()->inc_cset_head());
1304       g1_policy()->clear_incremental_cset();
1305       g1_policy()->stop_incremental_cset_building();
1306 
1307       tear_down_region_sets(false /* free_list_only */);
1308       collector_state()->set_gcs_are_young(true);
1309 
1310       // See the comments in g1CollectedHeap.hpp and
1311       // G1CollectedHeap::ref_processing_init() about
1312       // how reference processing currently works in G1.
1313 
1314       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1315       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1316 
1317       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1318       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1319 
1320       ref_processor_stw()->enable_discovery();
1321       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1322 
1323       // Do collection work
1324       {
1325         HandleMark hm;  // Discard invalid handles created during gc
1326         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1327       }
1328 
1329       assert(num_free_regions() == 0, "we should not have added any free regions");
1330       rebuild_region_sets(false /* free_list_only */);
1331 
1332       // Enqueue any discovered reference objects that have
1333       // not been removed from the discovered lists.
1334       ref_processor_stw()->enqueue_discovered_references();
1335 
1336 #if defined(COMPILER2) || INCLUDE_JVMCI
1337       DerivedPointerTable::update_pointers();
1338 #endif
1339 
1340       MemoryService::track_memory_usage();
1341 
1342       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1343       ref_processor_stw()->verify_no_references_recorded();
1344 
1345       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1346       ClassLoaderDataGraph::purge();
1347       MetaspaceAux::verify_metrics();
1348 
1349       // Note: since we've just done a full GC, concurrent
1350       // marking is no longer active. Therefore we need not
1351       // re-enable reference discovery for the CM ref processor.
1352       // That will be done at the start of the next marking cycle.
1353       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1354       ref_processor_cm()->verify_no_references_recorded();
1355 
1356       reset_gc_time_stamp();
1357       // Since everything potentially moved, we will clear all remembered
1358       // sets, and clear all cards.  Later we will rebuild remembered
1359       // sets. We will also reset the GC time stamps of the regions.
1360       clear_rsets_post_compaction();
1361       check_gc_time_stamps();
1362 
1363       resize_if_necessary_after_full_collection();
1364 
1365       // We should do this after we potentially resize the heap so
1366       // that all the COMMIT / UNCOMMIT events are generated before
1367       // the compaction events.
1368       print_hrm_post_compaction();
1369 
1370       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1371       if (hot_card_cache->use_cache()) {
1372         hot_card_cache->reset_card_counts();
1373         hot_card_cache->reset_hot_cache();
1374       }
1375 
1376       // Rebuild remembered sets of all regions.
1377       uint n_workers =
1378         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1379                                                 workers()->active_workers(),
1380                                                 Threads::number_of_non_daemon_threads());
1381       workers()->set_active_workers(n_workers);
1382 
1383       ParRebuildRSTask rebuild_rs_task(this);
1384       workers()->run_task(&rebuild_rs_task);
1385 
1386       // Rebuild the strong code root lists for each region
1387       rebuild_strong_code_roots();
1388 
1389       if (true) { // FIXME
1390         MetaspaceGC::compute_new_size();
1391       }
1392 
1393 #ifdef TRACESPINNING
1394       ParallelTaskTerminator::print_termination_counts();
1395 #endif
1396 
1397       // Discard all rset updates
1398       JavaThread::dirty_card_queue_set().abandon_logs();
1399       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1400 
1401       _young_list->reset_sampled_info();
1402       // At this point there should be no regions in the
1403       // entire heap tagged as young.
1404       assert(check_young_list_empty(true /* check_heap */),
1405              "young list should be empty at this point");
1406 
1407       // Update the number of full collections that have been completed.
1408       increment_old_marking_cycles_completed(false /* concurrent */);
1409 
1410       _hrm.verify_optional();
1411       verify_region_sets_optional();
1412 
1413       verify_after_gc();
1414 
1415       // Clear the previous marking bitmap, if needed for bitmap verification.
1416       // Note we cannot do this when we clear the next marking bitmap in
1417       // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1418       // objects marked during a full GC against the previous bitmap.
1419       // But we need to clear it before calling check_bitmaps below since
1420       // the full GC has compacted objects and updated TAMS but not updated
1421       // the prev bitmap.
1422       if (G1VerifyBitmaps) {
1423         ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1424       }
1425       check_bitmaps("Full GC End");
1426 
1427       // Start a new incremental collection set for the next pause
1428       assert(g1_policy()->collection_set() == NULL, "must be");
1429       g1_policy()->start_incremental_cset_building();
1430 
1431       clear_cset_fast_test();
1432 
1433       _allocator->init_mutator_alloc_region();
1434 
1435       g1_policy()->record_full_collection_end();
1436 
1437       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1438       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1439       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1440       // before any GC notifications are raised.
1441       g1mm()->update_sizes();
1442 
1443       gc_epilogue(true);
1444     }
1445 
1446     g1_policy()->print_detailed_heap_transition();
1447 
1448     print_heap_after_gc();
1449     trace_heap_after_gc(gc_tracer);
1450 
1451     post_full_gc_dump(gc_timer);
1452 
1453     gc_timer->register_gc_end();
1454     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1455   }
1456 
1457   return true;
1458 }
1459 
1460 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1461   // Currently, there is no facility in the do_full_collection(bool) API to notify
1462   // the caller that the collection did not succeed (e.g., because it was locked
1463   // out by the GC locker). So, right now, we'll ignore the return value.
1464   bool dummy = do_full_collection(true,                /* explicit_gc */
1465                                   clear_all_soft_refs);
1466 }
1467 
1468 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1469   // Include bytes that will be pre-allocated to support collections, as "used".
1470   const size_t used_after_gc = used();
1471   const size_t capacity_after_gc = capacity();
1472   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1473 
1474   // This is enforced in arguments.cpp.
1475   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1476          "otherwise the code below doesn't make sense");
1477 
1478   // We don't have floating point command-line arguments
1479   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1480   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1481   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1482   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1483 
1484   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1485   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1486 
1487   // We have to be careful here as these two calculations can overflow
1488   // 32-bit size_t's.
1489   double used_after_gc_d = (double) used_after_gc;
1490   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1491   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1492 
1493   // Let's make sure that they are both under the max heap size, which
1494   // by default will make them fit into a size_t.
1495   double desired_capacity_upper_bound = (double) max_heap_size;
1496   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1497                                     desired_capacity_upper_bound);
1498   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1499                                     desired_capacity_upper_bound);
1500 
1501   // We can now safely turn them into size_t's.
1502   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1503   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1504 
1505   // This assert only makes sense here, before we adjust them
1506   // with respect to the min and max heap size.
1507   assert(minimum_desired_capacity <= maximum_desired_capacity,
1508          "minimum_desired_capacity = " SIZE_FORMAT ", "
1509          "maximum_desired_capacity = " SIZE_FORMAT,
1510          minimum_desired_capacity, maximum_desired_capacity);
1511 
1512   // Should not be greater than the heap max size. No need to adjust
1513   // it with respect to the heap min size as it's a lower bound (i.e.,
1514   // we'll try to make the capacity larger than it, not smaller).
1515   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1516   // Should not be less than the heap min size. No need to adjust it
1517   // with respect to the heap max size as it's an upper bound (i.e.,
1518   // we'll try to make the capacity smaller than it, not greater).
1519   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1520 
1521   if (capacity_after_gc < minimum_desired_capacity) {
1522     // Don't expand unless it's significant
1523     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1524 
1525     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1526                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1527                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1528 
1529     expand(expand_bytes);
1530 
1531     // No expansion, now see if we want to shrink
1532   } else if (capacity_after_gc > maximum_desired_capacity) {
1533     // Capacity too large, compute shrinking size
1534     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1535 
1536     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1537                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1538                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1539 
1540     shrink(shrink_bytes);
1541   }
1542 }
1543 
1544 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1545                                                             AllocationContext_t context,
1546                                                             bool do_gc,
1547                                                             bool clear_all_soft_refs,
1548                                                             bool expect_null_mutator_alloc_region,
1549                                                             bool* gc_succeeded) {
1550   *gc_succeeded = true;
1551   // Let's attempt the allocation first.
1552   HeapWord* result =
1553     attempt_allocation_at_safepoint(word_size,
1554                                     context,
1555                                     expect_null_mutator_alloc_region);
1556   if (result != NULL) {
1557     assert(*gc_succeeded, "sanity");
1558     return result;
1559   }
1560 
1561   // In a G1 heap, we're supposed to keep allocation from failing by
1562   // incremental pauses.  Therefore, at least for now, we'll favor
1563   // expansion over collection.  (This might change in the future if we can
1564   // do something smarter than full collection to satisfy a failed alloc.)
1565   result = expand_and_allocate(word_size, context);
1566   if (result != NULL) {
1567     assert(*gc_succeeded, "sanity");
1568     return result;
1569   }
1570 
1571   if (do_gc) {
1572     // Expansion didn't work, we'll try to do a Full GC.
1573     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1574                                        clear_all_soft_refs);
1575   }
1576 
1577   return NULL;
1578 }
1579 
1580 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1581                                                      AllocationContext_t context,
1582                                                      bool* succeeded) {
1583   assert_at_safepoint(true /* should_be_vm_thread */);
1584 
1585   // Attempts to allocate followed by Full GC.
1586   HeapWord* result =
1587     satisfy_failed_allocation_helper(word_size,
1588                                      context,
1589                                      true,  /* do_gc */
1590                                      false, /* clear_all_soft_refs */
1591                                      false, /* expect_null_mutator_alloc_region */
1592                                      succeeded);
1593 
1594   if (result != NULL || !*succeeded) {
1595     return result;
1596   }
1597 
1598   // Attempts to allocate followed by Full GC that will collect all soft references.
1599   result = satisfy_failed_allocation_helper(word_size,
1600                                             context,
1601                                             true, /* do_gc */
1602                                             true, /* clear_all_soft_refs */
1603                                             true, /* expect_null_mutator_alloc_region */
1604                                             succeeded);
1605 
1606   if (result != NULL || !*succeeded) {
1607     return result;
1608   }
1609 
1610   // Attempts to allocate, no GC
1611   result = satisfy_failed_allocation_helper(word_size,
1612                                             context,
1613                                             false, /* do_gc */
1614                                             false, /* clear_all_soft_refs */
1615                                             true,  /* expect_null_mutator_alloc_region */
1616                                             succeeded);
1617 
1618   if (result != NULL) {
1619     assert(*succeeded, "sanity");
1620     return result;
1621   }
1622 
1623   assert(!collector_policy()->should_clear_all_soft_refs(),
1624          "Flag should have been handled and cleared prior to this point");
1625 
1626   // What else?  We might try synchronous finalization later.  If the total
1627   // space available is large enough for the allocation, then a more
1628   // complete compaction phase than we've tried so far might be
1629   // appropriate.
1630   assert(*succeeded, "sanity");
1631   return NULL;
1632 }
1633 
1634 // Attempting to expand the heap sufficiently
1635 // to support an allocation of the given "word_size".  If
1636 // successful, perform the allocation and return the address of the
1637 // allocated block, or else "NULL".
1638 
1639 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1640   assert_at_safepoint(true /* should_be_vm_thread */);
1641 
1642   verify_region_sets_optional();
1643 
1644   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1645   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1646                             word_size * HeapWordSize);
1647 
1648 
1649   if (expand(expand_bytes)) {
1650     _hrm.verify_optional();
1651     verify_region_sets_optional();
1652     return attempt_allocation_at_safepoint(word_size,
1653                                            context,
1654                                            false /* expect_null_mutator_alloc_region */);
1655   }
1656   return NULL;
1657 }
1658 
1659 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1660   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1661   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1662                                        HeapRegion::GrainBytes);
1663 
1664   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1665                             expand_bytes, aligned_expand_bytes);
1666 
1667   if (is_maximal_no_gc()) {
1668     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1669     return false;
1670   }
1671 
1672   double expand_heap_start_time_sec = os::elapsedTime();
1673   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1674   assert(regions_to_expand > 0, "Must expand by at least one region");
1675 
1676   uint expanded_by = _hrm.expand_by(regions_to_expand);
1677   if (expand_time_ms != NULL) {
1678     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1679   }
1680 
1681   if (expanded_by > 0) {
1682     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1683     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1684     g1_policy()->record_new_heap_size(num_regions());
1685   } else {
1686     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1687 
1688     // The expansion of the virtual storage space was unsuccessful.
1689     // Let's see if it was because we ran out of swap.
1690     if (G1ExitOnExpansionFailure &&
1691         _hrm.available() >= regions_to_expand) {
1692       // We had head room...
1693       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1694     }
1695   }
1696   return regions_to_expand > 0;
1697 }
1698 
1699 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1700   size_t aligned_shrink_bytes =
1701     ReservedSpace::page_align_size_down(shrink_bytes);
1702   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1703                                          HeapRegion::GrainBytes);
1704   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1705 
1706   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1707   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1708 
1709 
1710   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",
1711                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1712   if (num_regions_removed > 0) {
1713     g1_policy()->record_new_heap_size(num_regions());
1714   } else {
1715     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1716   }
1717 }
1718 
1719 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1720   verify_region_sets_optional();
1721 
1722   // We should only reach here at the end of a Full GC which means we
1723   // should not not be holding to any GC alloc regions. The method
1724   // below will make sure of that and do any remaining clean up.
1725   _allocator->abandon_gc_alloc_regions();
1726 
1727   // Instead of tearing down / rebuilding the free lists here, we
1728   // could instead use the remove_all_pending() method on free_list to
1729   // remove only the ones that we need to remove.
1730   tear_down_region_sets(true /* free_list_only */);
1731   shrink_helper(shrink_bytes);
1732   rebuild_region_sets(true /* free_list_only */);
1733 
1734   _hrm.verify_optional();
1735   verify_region_sets_optional();
1736 }
1737 
1738 // Public methods.
1739 
1740 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1741   CollectedHeap(),
1742   _g1_policy(policy_),
1743   _dirty_card_queue_set(false),
1744   _is_alive_closure_cm(this),
1745   _is_alive_closure_stw(this),
1746   _ref_processor_cm(NULL),
1747   _ref_processor_stw(NULL),
1748   _bot(NULL),
1749   _cg1r(NULL),
1750   _g1mm(NULL),
1751   _refine_cte_cl(NULL),
1752   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1753   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1754   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1755   _humongous_reclaim_candidates(),
1756   _has_humongous_reclaim_candidates(false),
1757   _archive_allocator(NULL),
1758   _free_regions_coming(false),
1759   _young_list(new YoungList(this)),
1760   _gc_time_stamp(0),
1761   _summary_bytes_used(0),
1762   _survivor_evac_stats(YoungPLABSize, PLABWeight),
1763   _old_evac_stats(OldPLABSize, PLABWeight),
1764   _expand_heap_after_alloc_failure(true),
1765   _old_marking_cycles_started(0),
1766   _old_marking_cycles_completed(0),
1767   _heap_summary_sent(false),
1768   _in_cset_fast_test(),
1769   _dirty_cards_region_list(NULL),
1770   _worker_cset_start_region(NULL),
1771   _worker_cset_start_region_time_stamp(NULL),
1772   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1773   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1774   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1775   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1776 
1777   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1778                           /* are_GC_task_threads */true,
1779                           /* are_ConcurrentGC_threads */false);
1780   _workers->initialize_workers();
1781 
1782   _allocator = G1Allocator::create_allocator(this);
1783   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1784 
1785   // Override the default _filler_array_max_size so that no humongous filler
1786   // objects are created.
1787   _filler_array_max_size = _humongous_object_threshold_in_words;
1788 
1789   uint n_queues = ParallelGCThreads;
1790   _task_queues = new RefToScanQueueSet(n_queues);
1791 
1792   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1793   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1794   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1795 
1796   for (uint i = 0; i < n_queues; i++) {
1797     RefToScanQueue* q = new RefToScanQueue();
1798     q->initialize();
1799     _task_queues->register_queue(i, q);
1800     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1801   }
1802   clear_cset_start_regions();
1803 
1804   // Initialize the G1EvacuationFailureALot counters and flags.
1805   NOT_PRODUCT(reset_evacuation_should_fail();)
1806 
1807   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1808 }
1809 
1810 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1811                                                                  size_t size,
1812                                                                  size_t translation_factor) {
1813   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1814   // Allocate a new reserved space, preferring to use large pages.
1815   ReservedSpace rs(size, preferred_page_size);
1816   G1RegionToSpaceMapper* result  =
1817     G1RegionToSpaceMapper::create_mapper(rs,
1818                                          size,
1819                                          rs.alignment(),
1820                                          HeapRegion::GrainBytes,
1821                                          translation_factor,
1822                                          mtGC);
1823   if (TracePageSizes) {
1824     tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1825                   description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1826   }
1827   return result;
1828 }
1829 
1830 jint G1CollectedHeap::initialize() {
1831   CollectedHeap::pre_initialize();
1832   os::enable_vtime();
1833 
1834   // Necessary to satisfy locking discipline assertions.
1835 
1836   MutexLocker x(Heap_lock);
1837 
1838   // While there are no constraints in the GC code that HeapWordSize
1839   // be any particular value, there are multiple other areas in the
1840   // system which believe this to be true (e.g. oop->object_size in some
1841   // cases incorrectly returns the size in wordSize units rather than
1842   // HeapWordSize).
1843   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1844 
1845   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1846   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1847   size_t heap_alignment = collector_policy()->heap_alignment();
1848 
1849   // Ensure that the sizes are properly aligned.
1850   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1851   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1852   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1853 
1854   _refine_cte_cl = new RefineCardTableEntryClosure();
1855 
1856   jint ecode = JNI_OK;
1857   _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1858   if (_cg1r == NULL) {
1859     return ecode;
1860   }
1861 
1862   // Reserve the maximum.
1863 
1864   // When compressed oops are enabled, the preferred heap base
1865   // is calculated by subtracting the requested size from the
1866   // 32Gb boundary and using the result as the base address for
1867   // heap reservation. If the requested size is not aligned to
1868   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1869   // into the ReservedHeapSpace constructor) then the actual
1870   // base of the reserved heap may end up differing from the
1871   // address that was requested (i.e. the preferred heap base).
1872   // If this happens then we could end up using a non-optimal
1873   // compressed oops mode.
1874 
1875   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1876                                                  heap_alignment);
1877 
1878   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1879 
1880   // Create the barrier set for the entire reserved region.
1881   G1SATBCardTableLoggingModRefBS* bs
1882     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1883   bs->initialize();
1884   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1885   set_barrier_set(bs);
1886 
1887   // Also create a G1 rem set.
1888   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1889 
1890   // Carve out the G1 part of the heap.
1891   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1892   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1893   G1RegionToSpaceMapper* heap_storage =
1894     G1RegionToSpaceMapper::create_mapper(g1_rs,
1895                                          g1_rs.size(),
1896                                          page_size,
1897                                          HeapRegion::GrainBytes,
1898                                          1,
1899                                          mtJavaHeap);
1900   os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1901                        max_byte_size, page_size,
1902                        heap_rs.base(),
1903                        heap_rs.size());
1904   heap_storage->set_mapping_changed_listener(&_listener);
1905 
1906   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1907   G1RegionToSpaceMapper* bot_storage =
1908     create_aux_memory_mapper("Block offset table",
1909                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1910                              G1BlockOffsetTable::heap_map_factor());
1911 
1912   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1913   G1RegionToSpaceMapper* cardtable_storage =
1914     create_aux_memory_mapper("Card table",
1915                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1916                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1917 
1918   G1RegionToSpaceMapper* card_counts_storage =
1919     create_aux_memory_mapper("Card counts table",
1920                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1921                              G1CardCounts::heap_map_factor());
1922 
1923   size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1924   G1RegionToSpaceMapper* prev_bitmap_storage =
1925     create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1926   G1RegionToSpaceMapper* next_bitmap_storage =
1927     create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1928 
1929   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1930   g1_barrier_set()->initialize(cardtable_storage);
1931    // Do later initialization work for concurrent refinement.
1932   _cg1r->init(card_counts_storage);
1933 
1934   // 6843694 - ensure that the maximum region index can fit
1935   // in the remembered set structures.
1936   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1937   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1938 
1939   G1RemSet::initialize(max_regions());
1940 
1941   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1942   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1943   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1944             "too many cards per region");
1945 
1946   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1947 
1948   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1949 
1950   {
1951     HeapWord* start = _hrm.reserved().start();
1952     HeapWord* end = _hrm.reserved().end();
1953     size_t granularity = HeapRegion::GrainBytes;
1954 
1955     _in_cset_fast_test.initialize(start, end, granularity);
1956     _humongous_reclaim_candidates.initialize(start, end, granularity);
1957   }
1958 
1959   // Create the ConcurrentMark data structure and thread.
1960   // (Must do this late, so that "max_regions" is defined.)
1961   _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1962   if (_cm == NULL || !_cm->completed_initialization()) {
1963     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1964     return JNI_ENOMEM;
1965   }
1966   _cmThread = _cm->cmThread();
1967 
1968   // Now expand into the initial heap size.
1969   if (!expand(init_byte_size)) {
1970     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1971     return JNI_ENOMEM;
1972   }
1973 
1974   // Perform any initialization actions delegated to the policy.
1975   g1_policy()->init();
1976 
1977   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1978                                                SATB_Q_FL_lock,
1979                                                G1SATBProcessCompletedThreshold,
1980                                                Shared_SATB_Q_lock);
1981 
1982   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1983                                                 DirtyCardQ_CBL_mon,
1984                                                 DirtyCardQ_FL_lock,
1985                                                 concurrent_g1_refine()->yellow_zone(),
1986                                                 concurrent_g1_refine()->red_zone(),
1987                                                 Shared_DirtyCardQ_lock,
1988                                                 NULL,  // fl_owner
1989                                                 true); // init_free_ids
1990 
1991   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1992                                     DirtyCardQ_CBL_mon,
1993                                     DirtyCardQ_FL_lock,
1994                                     -1, // never trigger processing
1995                                     -1, // no limit on length
1996                                     Shared_DirtyCardQ_lock,
1997                                     &JavaThread::dirty_card_queue_set());
1998 
1999   // Here we allocate the dummy HeapRegion that is required by the
2000   // G1AllocRegion class.
2001   HeapRegion* dummy_region = _hrm.get_dummy_region();
2002 
2003   // We'll re-use the same region whether the alloc region will
2004   // require BOT updates or not and, if it doesn't, then a non-young
2005   // region will complain that it cannot support allocations without
2006   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2007   dummy_region->set_eden();
2008   // Make sure it's full.
2009   dummy_region->set_top(dummy_region->end());
2010   G1AllocRegion::setup(this, dummy_region);
2011 
2012   _allocator->init_mutator_alloc_region();
2013 
2014   // Do create of the monitoring and management support so that
2015   // values in the heap have been properly initialized.
2016   _g1mm = new G1MonitoringSupport(this);
2017 
2018   G1StringDedup::initialize();
2019 
2020   _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2021   for (uint i = 0; i < ParallelGCThreads; i++) {
2022     new (&_preserved_objs[i]) OopAndMarkOopStack();
2023   }
2024 
2025   return JNI_OK;
2026 }
2027 
2028 void G1CollectedHeap::stop() {
2029   // Stop all concurrent threads. We do this to make sure these threads
2030   // do not continue to execute and access resources (e.g. logging)
2031   // that are destroyed during shutdown.
2032   _cg1r->stop();
2033   _cmThread->stop();
2034   if (G1StringDedup::is_enabled()) {
2035     G1StringDedup::stop();
2036   }
2037 }
2038 
2039 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2040   return HeapRegion::max_region_size();
2041 }
2042 
2043 void G1CollectedHeap::post_initialize() {
2044   CollectedHeap::post_initialize();
2045   ref_processing_init();
2046 }
2047 
2048 void G1CollectedHeap::ref_processing_init() {
2049   // Reference processing in G1 currently works as follows:
2050   //
2051   // * There are two reference processor instances. One is
2052   //   used to record and process discovered references
2053   //   during concurrent marking; the other is used to
2054   //   record and process references during STW pauses
2055   //   (both full and incremental).
2056   // * Both ref processors need to 'span' the entire heap as
2057   //   the regions in the collection set may be dotted around.
2058   //
2059   // * For the concurrent marking ref processor:
2060   //   * Reference discovery is enabled at initial marking.
2061   //   * Reference discovery is disabled and the discovered
2062   //     references processed etc during remarking.
2063   //   * Reference discovery is MT (see below).
2064   //   * Reference discovery requires a barrier (see below).
2065   //   * Reference processing may or may not be MT
2066   //     (depending on the value of ParallelRefProcEnabled
2067   //     and ParallelGCThreads).
2068   //   * A full GC disables reference discovery by the CM
2069   //     ref processor and abandons any entries on it's
2070   //     discovered lists.
2071   //
2072   // * For the STW processor:
2073   //   * Non MT discovery is enabled at the start of a full GC.
2074   //   * Processing and enqueueing during a full GC is non-MT.
2075   //   * During a full GC, references are processed after marking.
2076   //
2077   //   * Discovery (may or may not be MT) is enabled at the start
2078   //     of an incremental evacuation pause.
2079   //   * References are processed near the end of a STW evacuation pause.
2080   //   * For both types of GC:
2081   //     * Discovery is atomic - i.e. not concurrent.
2082   //     * Reference discovery will not need a barrier.
2083 
2084   MemRegion mr = reserved_region();
2085 
2086   // Concurrent Mark ref processor
2087   _ref_processor_cm =
2088     new ReferenceProcessor(mr,    // span
2089                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2090                                 // mt processing
2091                            ParallelGCThreads,
2092                                 // degree of mt processing
2093                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2094                                 // mt discovery
2095                            MAX2(ParallelGCThreads, ConcGCThreads),
2096                                 // degree of mt discovery
2097                            false,
2098                                 // Reference discovery is not atomic
2099                            &_is_alive_closure_cm);
2100                                 // is alive closure
2101                                 // (for efficiency/performance)
2102 
2103   // STW ref processor
2104   _ref_processor_stw =
2105     new ReferenceProcessor(mr,    // span
2106                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2107                                 // mt processing
2108                            ParallelGCThreads,
2109                                 // degree of mt processing
2110                            (ParallelGCThreads > 1),
2111                                 // mt discovery
2112                            ParallelGCThreads,
2113                                 // degree of mt discovery
2114                            true,
2115                                 // Reference discovery is atomic
2116                            &_is_alive_closure_stw);
2117                                 // is alive closure
2118                                 // (for efficiency/performance)
2119 }
2120 
2121 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2122   return g1_policy();
2123 }
2124 
2125 size_t G1CollectedHeap::capacity() const {
2126   return _hrm.length() * HeapRegion::GrainBytes;
2127 }
2128 
2129 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2130   hr->reset_gc_time_stamp();
2131 }
2132 
2133 #ifndef PRODUCT
2134 
2135 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2136 private:
2137   unsigned _gc_time_stamp;
2138   bool _failures;
2139 
2140 public:
2141   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2142     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2143 
2144   virtual bool doHeapRegion(HeapRegion* hr) {
2145     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2146     if (_gc_time_stamp != region_gc_time_stamp) {
2147       log_info(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2148                            region_gc_time_stamp, _gc_time_stamp);
2149       _failures = true;
2150     }
2151     return false;
2152   }
2153 
2154   bool failures() { return _failures; }
2155 };
2156 
2157 void G1CollectedHeap::check_gc_time_stamps() {
2158   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2159   heap_region_iterate(&cl);
2160   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2161 }
2162 #endif // PRODUCT
2163 
2164 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2165   _cg1r->hot_card_cache()->drain(cl, worker_i);
2166 }
2167 
2168 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2169   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2170   size_t n_completed_buffers = 0;
2171   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2172     n_completed_buffers++;
2173   }
2174   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2175   dcqs.clear_n_completed_buffers();
2176   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2177 }
2178 
2179 // Computes the sum of the storage used by the various regions.
2180 size_t G1CollectedHeap::used() const {
2181   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2182   if (_archive_allocator != NULL) {
2183     result += _archive_allocator->used();
2184   }
2185   return result;
2186 }
2187 
2188 size_t G1CollectedHeap::used_unlocked() const {
2189   return _summary_bytes_used;
2190 }
2191 
2192 class SumUsedClosure: public HeapRegionClosure {
2193   size_t _used;
2194 public:
2195   SumUsedClosure() : _used(0) {}
2196   bool doHeapRegion(HeapRegion* r) {
2197     _used += r->used();
2198     return false;
2199   }
2200   size_t result() { return _used; }
2201 };
2202 
2203 size_t G1CollectedHeap::recalculate_used() const {
2204   double recalculate_used_start = os::elapsedTime();
2205 
2206   SumUsedClosure blk;
2207   heap_region_iterate(&blk);
2208 
2209   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2210   return blk.result();
2211 }
2212 
2213 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2214   switch (cause) {
2215     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2216     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2217     case GCCause::_update_allocation_context_stats_inc: return true;
2218     case GCCause::_wb_conc_mark:                        return true;
2219     default :                                           return false;
2220   }
2221 }
2222 
2223 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2224   switch (cause) {
2225     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2226     case GCCause::_g1_humongous_allocation: return true;
2227     default:                                return is_user_requested_concurrent_full_gc(cause);
2228   }
2229 }
2230 
2231 #ifndef PRODUCT
2232 void G1CollectedHeap::allocate_dummy_regions() {
2233   // Let's fill up most of the region
2234   size_t word_size = HeapRegion::GrainWords - 1024;
2235   // And as a result the region we'll allocate will be humongous.
2236   guarantee(is_humongous(word_size), "sanity");
2237 
2238   // _filler_array_max_size is set to humongous object threshold
2239   // but temporarily change it to use CollectedHeap::fill_with_object().
2240   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2241 
2242   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2243     // Let's use the existing mechanism for the allocation
2244     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2245                                                  AllocationContext::system());
2246     if (dummy_obj != NULL) {
2247       MemRegion mr(dummy_obj, word_size);
2248       CollectedHeap::fill_with_object(mr);
2249     } else {
2250       // If we can't allocate once, we probably cannot allocate
2251       // again. Let's get out of the loop.
2252       break;
2253     }
2254   }
2255 }
2256 #endif // !PRODUCT
2257 
2258 void G1CollectedHeap::increment_old_marking_cycles_started() {
2259   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2260          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2261          "Wrong marking cycle count (started: %d, completed: %d)",
2262          _old_marking_cycles_started, _old_marking_cycles_completed);
2263 
2264   _old_marking_cycles_started++;
2265 }
2266 
2267 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2268   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2269 
2270   // We assume that if concurrent == true, then the caller is a
2271   // concurrent thread that was joined the Suspendible Thread
2272   // Set. If there's ever a cheap way to check this, we should add an
2273   // assert here.
2274 
2275   // Given that this method is called at the end of a Full GC or of a
2276   // concurrent cycle, and those can be nested (i.e., a Full GC can
2277   // interrupt a concurrent cycle), the number of full collections
2278   // completed should be either one (in the case where there was no
2279   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2280   // behind the number of full collections started.
2281 
2282   // This is the case for the inner caller, i.e. a Full GC.
2283   assert(concurrent ||
2284          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2285          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2286          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2287          "is inconsistent with _old_marking_cycles_completed = %u",
2288          _old_marking_cycles_started, _old_marking_cycles_completed);
2289 
2290   // This is the case for the outer caller, i.e. the concurrent cycle.
2291   assert(!concurrent ||
2292          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2293          "for outer caller (concurrent cycle): "
2294          "_old_marking_cycles_started = %u "
2295          "is inconsistent with _old_marking_cycles_completed = %u",
2296          _old_marking_cycles_started, _old_marking_cycles_completed);
2297 
2298   _old_marking_cycles_completed += 1;
2299 
2300   // We need to clear the "in_progress" flag in the CM thread before
2301   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2302   // is set) so that if a waiter requests another System.gc() it doesn't
2303   // incorrectly see that a marking cycle is still in progress.
2304   if (concurrent) {
2305     _cmThread->set_idle();
2306   }
2307 
2308   // This notify_all() will ensure that a thread that called
2309   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2310   // and it's waiting for a full GC to finish will be woken up. It is
2311   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2312   FullGCCount_lock->notify_all();
2313 }
2314 
2315 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2316   GCIdMarkAndRestore conc_gc_id_mark;
2317   collector_state()->set_concurrent_cycle_started(true);
2318   _gc_timer_cm->register_gc_start(start_time);
2319 
2320   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2321   trace_heap_before_gc(_gc_tracer_cm);
2322   _cmThread->set_gc_id(GCId::current());
2323 }
2324 
2325 void G1CollectedHeap::register_concurrent_cycle_end() {
2326   if (collector_state()->concurrent_cycle_started()) {
2327     GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2328     if (_cm->has_aborted()) {
2329       _gc_tracer_cm->report_concurrent_mode_failure();
2330     }
2331 
2332     _gc_timer_cm->register_gc_end();
2333     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2334 
2335     // Clear state variables to prepare for the next concurrent cycle.
2336     collector_state()->set_concurrent_cycle_started(false);
2337     _heap_summary_sent = false;
2338   }
2339 }
2340 
2341 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2342   if (collector_state()->concurrent_cycle_started()) {
2343     // This function can be called when:
2344     //  the cleanup pause is run
2345     //  the concurrent cycle is aborted before the cleanup pause.
2346     //  the concurrent cycle is aborted after the cleanup pause,
2347     //   but before the concurrent cycle end has been registered.
2348     // Make sure that we only send the heap information once.
2349     if (!_heap_summary_sent) {
2350       GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2351       trace_heap_after_gc(_gc_tracer_cm);
2352       _heap_summary_sent = true;
2353     }
2354   }
2355 }
2356 
2357 void G1CollectedHeap::collect(GCCause::Cause cause) {
2358   assert_heap_not_locked();
2359 
2360   uint gc_count_before;
2361   uint old_marking_count_before;
2362   uint full_gc_count_before;
2363   bool retry_gc;
2364 
2365   do {
2366     retry_gc = false;
2367 
2368     {
2369       MutexLocker ml(Heap_lock);
2370 
2371       // Read the GC count while holding the Heap_lock
2372       gc_count_before = total_collections();
2373       full_gc_count_before = total_full_collections();
2374       old_marking_count_before = _old_marking_cycles_started;
2375     }
2376 
2377     if (should_do_concurrent_full_gc(cause)) {
2378       // Schedule an initial-mark evacuation pause that will start a
2379       // concurrent cycle. We're setting word_size to 0 which means that
2380       // we are not requesting a post-GC allocation.
2381       VM_G1IncCollectionPause op(gc_count_before,
2382                                  0,     /* word_size */
2383                                  true,  /* should_initiate_conc_mark */
2384                                  g1_policy()->max_pause_time_ms(),
2385                                  cause);
2386       op.set_allocation_context(AllocationContext::current());
2387 
2388       VMThread::execute(&op);
2389       if (!op.pause_succeeded()) {
2390         if (old_marking_count_before == _old_marking_cycles_started) {
2391           retry_gc = op.should_retry_gc();
2392         } else {
2393           // A Full GC happened while we were trying to schedule the
2394           // initial-mark GC. No point in starting a new cycle given
2395           // that the whole heap was collected anyway.
2396         }
2397 
2398         if (retry_gc) {
2399           if (GCLocker::is_active_and_needs_gc()) {
2400             GCLocker::stall_until_clear();
2401           }
2402         }
2403       }
2404     } else {
2405       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2406           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2407 
2408         // Schedule a standard evacuation pause. We're setting word_size
2409         // to 0 which means that we are not requesting a post-GC allocation.
2410         VM_G1IncCollectionPause op(gc_count_before,
2411                                    0,     /* word_size */
2412                                    false, /* should_initiate_conc_mark */
2413                                    g1_policy()->max_pause_time_ms(),
2414                                    cause);
2415         VMThread::execute(&op);
2416       } else {
2417         // Schedule a Full GC.
2418         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2419         VMThread::execute(&op);
2420       }
2421     }
2422   } while (retry_gc);
2423 }
2424 
2425 bool G1CollectedHeap::is_in(const void* p) const {
2426   if (_hrm.reserved().contains(p)) {
2427     // Given that we know that p is in the reserved space,
2428     // heap_region_containing() should successfully
2429     // return the containing region.
2430     HeapRegion* hr = heap_region_containing(p);
2431     return hr->is_in(p);
2432   } else {
2433     return false;
2434   }
2435 }
2436 
2437 #ifdef ASSERT
2438 bool G1CollectedHeap::is_in_exact(const void* p) const {
2439   bool contains = reserved_region().contains(p);
2440   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2441   if (contains && available) {
2442     return true;
2443   } else {
2444     return false;
2445   }
2446 }
2447 #endif
2448 
2449 bool G1CollectedHeap::obj_in_cs(oop obj) {
2450   HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2451   return r != NULL && r->in_collection_set();
2452 }
2453 
2454 // Iteration functions.
2455 
2456 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2457 
2458 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2459   ExtendedOopClosure* _cl;
2460 public:
2461   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2462   bool doHeapRegion(HeapRegion* r) {
2463     if (!r->is_continues_humongous()) {
2464       r->oop_iterate(_cl);
2465     }
2466     return false;
2467   }
2468 };
2469 
2470 // Iterates an ObjectClosure over all objects within a HeapRegion.
2471 
2472 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2473   ObjectClosure* _cl;
2474 public:
2475   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2476   bool doHeapRegion(HeapRegion* r) {
2477     if (!r->is_continues_humongous()) {
2478       r->object_iterate(_cl);
2479     }
2480     return false;
2481   }
2482 };
2483 
2484 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2485   IterateObjectClosureRegionClosure blk(cl);
2486   heap_region_iterate(&blk);
2487 }
2488 
2489 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2490   _hrm.iterate(cl);
2491 }
2492 
2493 void
2494 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2495                                          uint worker_id,
2496                                          HeapRegionClaimer *hrclaimer,
2497                                          bool concurrent) const {
2498   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2499 }
2500 
2501 // Clear the cached CSet starting regions and (more importantly)
2502 // the time stamps. Called when we reset the GC time stamp.
2503 void G1CollectedHeap::clear_cset_start_regions() {
2504   assert(_worker_cset_start_region != NULL, "sanity");
2505   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2506 
2507   for (uint i = 0; i < ParallelGCThreads; i++) {
2508     _worker_cset_start_region[i] = NULL;
2509     _worker_cset_start_region_time_stamp[i] = 0;
2510   }
2511 }
2512 
2513 // Given the id of a worker, obtain or calculate a suitable
2514 // starting region for iterating over the current collection set.
2515 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2516   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2517 
2518   HeapRegion* result = NULL;
2519   unsigned gc_time_stamp = get_gc_time_stamp();
2520 
2521   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2522     // Cached starting region for current worker was set
2523     // during the current pause - so it's valid.
2524     // Note: the cached starting heap region may be NULL
2525     // (when the collection set is empty).
2526     result = _worker_cset_start_region[worker_i];
2527     assert(result == NULL || result->in_collection_set(), "sanity");
2528     return result;
2529   }
2530 
2531   // The cached entry was not valid so let's calculate
2532   // a suitable starting heap region for this worker.
2533 
2534   // We want the parallel threads to start their collection
2535   // set iteration at different collection set regions to
2536   // avoid contention.
2537   // If we have:
2538   //          n collection set regions
2539   //          p threads
2540   // Then thread t will start at region floor ((t * n) / p)
2541 
2542   result = g1_policy()->collection_set();
2543   uint cs_size = g1_policy()->cset_region_length();
2544   uint active_workers = workers()->active_workers();
2545 
2546   uint end_ind   = (cs_size * worker_i) / active_workers;
2547   uint start_ind = 0;
2548 
2549   if (worker_i > 0 &&
2550       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2551     // Previous workers starting region is valid
2552     // so let's iterate from there
2553     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2554     OrderAccess::loadload();
2555     result = _worker_cset_start_region[worker_i - 1];
2556   }
2557 
2558   for (uint i = start_ind; i < end_ind; i++) {
2559     result = result->next_in_collection_set();
2560   }
2561 
2562   // Note: the calculated starting heap region may be NULL
2563   // (when the collection set is empty).
2564   assert(result == NULL || result->in_collection_set(), "sanity");
2565   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2566          "should be updated only once per pause");
2567   _worker_cset_start_region[worker_i] = result;
2568   OrderAccess::storestore();
2569   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2570   return result;
2571 }
2572 
2573 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2574   HeapRegion* r = g1_policy()->collection_set();
2575   while (r != NULL) {
2576     HeapRegion* next = r->next_in_collection_set();
2577     if (cl->doHeapRegion(r)) {
2578       cl->incomplete();
2579       return;
2580     }
2581     r = next;
2582   }
2583 }
2584 
2585 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2586                                                   HeapRegionClosure *cl) {
2587   if (r == NULL) {
2588     // The CSet is empty so there's nothing to do.
2589     return;
2590   }
2591 
2592   assert(r->in_collection_set(),
2593          "Start region must be a member of the collection set.");
2594   HeapRegion* cur = r;
2595   while (cur != NULL) {
2596     HeapRegion* next = cur->next_in_collection_set();
2597     if (cl->doHeapRegion(cur) && false) {
2598       cl->incomplete();
2599       return;
2600     }
2601     cur = next;
2602   }
2603   cur = g1_policy()->collection_set();
2604   while (cur != r) {
2605     HeapRegion* next = cur->next_in_collection_set();
2606     if (cl->doHeapRegion(cur) && false) {
2607       cl->incomplete();
2608       return;
2609     }
2610     cur = next;
2611   }
2612 }
2613 
2614 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2615   HeapRegion* result = _hrm.next_region_in_heap(from);
2616   while (result != NULL && result->is_pinned()) {
2617     result = _hrm.next_region_in_heap(result);
2618   }
2619   return result;
2620 }
2621 
2622 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2623   HeapRegion* hr = heap_region_containing(addr);
2624   return hr->block_start(addr);
2625 }
2626 
2627 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2628   HeapRegion* hr = heap_region_containing(addr);
2629   return hr->block_size(addr);
2630 }
2631 
2632 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2633   HeapRegion* hr = heap_region_containing(addr);
2634   return hr->block_is_obj(addr);
2635 }
2636 
2637 bool G1CollectedHeap::supports_tlab_allocation() const {
2638   return true;
2639 }
2640 
2641 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2642   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2643 }
2644 
2645 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2646   return young_list()->eden_used_bytes();
2647 }
2648 
2649 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2650 // must be equal to the humongous object limit.
2651 size_t G1CollectedHeap::max_tlab_size() const {
2652   return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2653 }
2654 
2655 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2656   AllocationContext_t context = AllocationContext::current();
2657   return _allocator->unsafe_max_tlab_alloc(context);
2658 }
2659 
2660 size_t G1CollectedHeap::max_capacity() const {
2661   return _hrm.reserved().byte_size();
2662 }
2663 
2664 jlong G1CollectedHeap::millis_since_last_gc() {
2665   // assert(false, "NYI");
2666   return 0;
2667 }
2668 
2669 void G1CollectedHeap::prepare_for_verify() {
2670   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2671     ensure_parsability(false);
2672   }
2673   g1_rem_set()->prepare_for_verify();
2674 }
2675 
2676 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2677                                               VerifyOption vo) {
2678   switch (vo) {
2679   case VerifyOption_G1UsePrevMarking:
2680     return hr->obj_allocated_since_prev_marking(obj);
2681   case VerifyOption_G1UseNextMarking:
2682     return hr->obj_allocated_since_next_marking(obj);
2683   case VerifyOption_G1UseMarkWord:
2684     return false;
2685   default:
2686     ShouldNotReachHere();
2687   }
2688   return false; // keep some compilers happy
2689 }
2690 
2691 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2692   switch (vo) {
2693   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2694   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2695   case VerifyOption_G1UseMarkWord:    return NULL;
2696   default:                            ShouldNotReachHere();
2697   }
2698   return NULL; // keep some compilers happy
2699 }
2700 
2701 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2702   switch (vo) {
2703   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2704   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2705   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
2706   default:                            ShouldNotReachHere();
2707   }
2708   return false; // keep some compilers happy
2709 }
2710 
2711 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2712   switch (vo) {
2713   case VerifyOption_G1UsePrevMarking: return "PTAMS";
2714   case VerifyOption_G1UseNextMarking: return "NTAMS";
2715   case VerifyOption_G1UseMarkWord:    return "NONE";
2716   default:                            ShouldNotReachHere();
2717   }
2718   return NULL; // keep some compilers happy
2719 }
2720 
2721 class VerifyRootsClosure: public OopClosure {
2722 private:
2723   G1CollectedHeap* _g1h;
2724   VerifyOption     _vo;
2725   bool             _failures;
2726 public:
2727   // _vo == UsePrevMarking -> use "prev" marking information,
2728   // _vo == UseNextMarking -> use "next" marking information,
2729   // _vo == UseMarkWord    -> use mark word from object header.
2730   VerifyRootsClosure(VerifyOption vo) :
2731     _g1h(G1CollectedHeap::heap()),
2732     _vo(vo),
2733     _failures(false) { }
2734 
2735   bool failures() { return _failures; }
2736 
2737   template <class T> void do_oop_nv(T* p) {
2738     T heap_oop = oopDesc::load_heap_oop(p);
2739     if (!oopDesc::is_null(heap_oop)) {
2740       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2741       if (_g1h->is_obj_dead_cond(obj, _vo)) {
2742         LogHandle(gc, verify) log;
2743         log.info("Root location " PTR_FORMAT " points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2744         if (_vo == VerifyOption_G1UseMarkWord) {
2745           log.info("  Mark word: " PTR_FORMAT, p2i(obj->mark()));
2746         }
2747         ResourceMark rm;
2748         obj->print_on(log.info_stream());
2749         _failures = true;
2750       }
2751     }
2752   }
2753 
2754   void do_oop(oop* p)       { do_oop_nv(p); }
2755   void do_oop(narrowOop* p) { do_oop_nv(p); }
2756 };
2757 
2758 class G1VerifyCodeRootOopClosure: public OopClosure {
2759   G1CollectedHeap* _g1h;
2760   OopClosure* _root_cl;
2761   nmethod* _nm;
2762   VerifyOption _vo;
2763   bool _failures;
2764 
2765   template <class T> void do_oop_work(T* p) {
2766     // First verify that this root is live
2767     _root_cl->do_oop(p);
2768 
2769     if (!G1VerifyHeapRegionCodeRoots) {
2770       // We're not verifying the code roots attached to heap region.
2771       return;
2772     }
2773 
2774     // Don't check the code roots during marking verification in a full GC
2775     if (_vo == VerifyOption_G1UseMarkWord) {
2776       return;
2777     }
2778 
2779     // Now verify that the current nmethod (which contains p) is
2780     // in the code root list of the heap region containing the
2781     // object referenced by p.
2782 
2783     T heap_oop = oopDesc::load_heap_oop(p);
2784     if (!oopDesc::is_null(heap_oop)) {
2785       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2786 
2787       // Now fetch the region containing the object
2788       HeapRegion* hr = _g1h->heap_region_containing(obj);
2789       HeapRegionRemSet* hrrs = hr->rem_set();
2790       // Verify that the strong code root list for this region
2791       // contains the nmethod
2792       if (!hrrs->strong_code_roots_list_contains(_nm)) {
2793         log_info(gc, verify)("Code root location " PTR_FORMAT " "
2794                              "from nmethod " PTR_FORMAT " not in strong "
2795                              "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2796                              p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2797         _failures = true;
2798       }
2799     }
2800   }
2801 
2802 public:
2803   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2804     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2805 
2806   void do_oop(oop* p) { do_oop_work(p); }
2807   void do_oop(narrowOop* p) { do_oop_work(p); }
2808 
2809   void set_nmethod(nmethod* nm) { _nm = nm; }
2810   bool failures() { return _failures; }
2811 };
2812 
2813 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2814   G1VerifyCodeRootOopClosure* _oop_cl;
2815 
2816 public:
2817   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2818     _oop_cl(oop_cl) {}
2819 
2820   void do_code_blob(CodeBlob* cb) {
2821     nmethod* nm = cb->as_nmethod_or_null();
2822     if (nm != NULL) {
2823       _oop_cl->set_nmethod(nm);
2824       nm->oops_do(_oop_cl);
2825     }
2826   }
2827 };
2828 
2829 class YoungRefCounterClosure : public OopClosure {
2830   G1CollectedHeap* _g1h;
2831   int              _count;
2832  public:
2833   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2834   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
2835   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2836 
2837   int count() { return _count; }
2838   void reset_count() { _count = 0; };
2839 };
2840 
2841 class VerifyKlassClosure: public KlassClosure {
2842   YoungRefCounterClosure _young_ref_counter_closure;
2843   OopClosure *_oop_closure;
2844  public:
2845   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2846   void do_klass(Klass* k) {
2847     k->oops_do(_oop_closure);
2848 
2849     _young_ref_counter_closure.reset_count();
2850     k->oops_do(&_young_ref_counter_closure);
2851     if (_young_ref_counter_closure.count() > 0) {
2852       guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2853     }
2854   }
2855 };
2856 
2857 class VerifyLivenessOopClosure: public OopClosure {
2858   G1CollectedHeap* _g1h;
2859   VerifyOption _vo;
2860 public:
2861   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2862     _g1h(g1h), _vo(vo)
2863   { }
2864   void do_oop(narrowOop *p) { do_oop_work(p); }
2865   void do_oop(      oop *p) { do_oop_work(p); }
2866 
2867   template <class T> void do_oop_work(T *p) {
2868     oop obj = oopDesc::load_decode_heap_oop(p);
2869     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2870               "Dead object referenced by a not dead object");
2871   }
2872 };
2873 
2874 class VerifyObjsInRegionClosure: public ObjectClosure {
2875 private:
2876   G1CollectedHeap* _g1h;
2877   size_t _live_bytes;
2878   HeapRegion *_hr;
2879   VerifyOption _vo;
2880 public:
2881   // _vo == UsePrevMarking -> use "prev" marking information,
2882   // _vo == UseNextMarking -> use "next" marking information,
2883   // _vo == UseMarkWord    -> use mark word from object header.
2884   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2885     : _live_bytes(0), _hr(hr), _vo(vo) {
2886     _g1h = G1CollectedHeap::heap();
2887   }
2888   void do_object(oop o) {
2889     VerifyLivenessOopClosure isLive(_g1h, _vo);
2890     assert(o != NULL, "Huh?");
2891     if (!_g1h->is_obj_dead_cond(o, _vo)) {
2892       // If the object is alive according to the mark word,
2893       // then verify that the marking information agrees.
2894       // Note we can't verify the contra-positive of the
2895       // above: if the object is dead (according to the mark
2896       // word), it may not be marked, or may have been marked
2897       // but has since became dead, or may have been allocated
2898       // since the last marking.
2899       if (_vo == VerifyOption_G1UseMarkWord) {
2900         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2901       }
2902 
2903       o->oop_iterate_no_header(&isLive);
2904       if (!_hr->obj_allocated_since_prev_marking(o)) {
2905         size_t obj_size = o->size();    // Make sure we don't overflow
2906         _live_bytes += (obj_size * HeapWordSize);
2907       }
2908     }
2909   }
2910   size_t live_bytes() { return _live_bytes; }
2911 };
2912 
2913 class VerifyArchiveOopClosure: public OopClosure {
2914 public:
2915   VerifyArchiveOopClosure(HeapRegion *hr) { }
2916   void do_oop(narrowOop *p) { do_oop_work(p); }
2917   void do_oop(      oop *p) { do_oop_work(p); }
2918 
2919   template <class T> void do_oop_work(T *p) {
2920     oop obj = oopDesc::load_decode_heap_oop(p);
2921     guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2922               "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2923               p2i(p), p2i(obj));
2924   }
2925 };
2926 
2927 class VerifyArchiveRegionClosure: public ObjectClosure {
2928 public:
2929   VerifyArchiveRegionClosure(HeapRegion *hr) { }
2930   // Verify that all object pointers are to archive regions.
2931   void do_object(oop o) {
2932     VerifyArchiveOopClosure checkOop(NULL);
2933     assert(o != NULL, "Should not be here for NULL oops");
2934     o->oop_iterate_no_header(&checkOop);
2935   }
2936 };
2937 
2938 class VerifyRegionClosure: public HeapRegionClosure {
2939 private:
2940   bool             _par;
2941   VerifyOption     _vo;
2942   bool             _failures;
2943 public:
2944   // _vo == UsePrevMarking -> use "prev" marking information,
2945   // _vo == UseNextMarking -> use "next" marking information,
2946   // _vo == UseMarkWord    -> use mark word from object header.
2947   VerifyRegionClosure(bool par, VerifyOption vo)
2948     : _par(par),
2949       _vo(vo),
2950       _failures(false) {}
2951 
2952   bool failures() {
2953     return _failures;
2954   }
2955 
2956   bool doHeapRegion(HeapRegion* r) {
2957     // For archive regions, verify there are no heap pointers to
2958     // non-pinned regions. For all others, verify liveness info.
2959     if (r->is_archive()) {
2960       VerifyArchiveRegionClosure verify_oop_pointers(r);
2961       r->object_iterate(&verify_oop_pointers);
2962       return true;
2963     }
2964     if (!r->is_continues_humongous()) {
2965       bool failures = false;
2966       r->verify(_vo, &failures);
2967       if (failures) {
2968         _failures = true;
2969       } else if (!r->is_starts_humongous()) {
2970         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2971         r->object_iterate(&not_dead_yet_cl);
2972         if (_vo != VerifyOption_G1UseNextMarking) {
2973           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2974             log_info(gc, verify)("[" PTR_FORMAT "," PTR_FORMAT "] max_live_bytes " SIZE_FORMAT " < calculated " SIZE_FORMAT,
2975                                  p2i(r->bottom()), p2i(r->end()), r->max_live_bytes(), not_dead_yet_cl.live_bytes());
2976             _failures = true;
2977           }
2978         } else {
2979           // When vo == UseNextMarking we cannot currently do a sanity
2980           // check on the live bytes as the calculation has not been
2981           // finalized yet.
2982         }
2983       }
2984     }
2985     return false; // stop the region iteration if we hit a failure
2986   }
2987 };
2988 
2989 // This is the task used for parallel verification of the heap regions
2990 
2991 class G1ParVerifyTask: public AbstractGangTask {
2992 private:
2993   G1CollectedHeap*  _g1h;
2994   VerifyOption      _vo;
2995   bool              _failures;
2996   HeapRegionClaimer _hrclaimer;
2997 
2998 public:
2999   // _vo == UsePrevMarking -> use "prev" marking information,
3000   // _vo == UseNextMarking -> use "next" marking information,
3001   // _vo == UseMarkWord    -> use mark word from object header.
3002   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3003       AbstractGangTask("Parallel verify task"),
3004       _g1h(g1h),
3005       _vo(vo),
3006       _failures(false),
3007       _hrclaimer(g1h->workers()->active_workers()) {}
3008 
3009   bool failures() {
3010     return _failures;
3011   }
3012 
3013   void work(uint worker_id) {
3014     HandleMark hm;
3015     VerifyRegionClosure blk(true, _vo);
3016     _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3017     if (blk.failures()) {
3018       _failures = true;
3019     }
3020   }
3021 };
3022 
3023 void G1CollectedHeap::verify(VerifyOption vo) {
3024   if (!SafepointSynchronize::is_at_safepoint()) {
3025     log_info(gc, verify)("Skipping verification. Not at safepoint.");
3026   }
3027 
3028   assert(Thread::current()->is_VM_thread(),
3029          "Expected to be executed serially by the VM thread at this point");
3030 
3031   log_debug(gc, verify)("Roots");
3032   VerifyRootsClosure rootsCl(vo);
3033   VerifyKlassClosure klassCl(this, &rootsCl);
3034   CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3035 
3036   // We apply the relevant closures to all the oops in the
3037   // system dictionary, class loader data graph, the string table
3038   // and the nmethods in the code cache.
3039   G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3040   G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3041 
3042   {
3043     G1RootProcessor root_processor(this, 1);
3044     root_processor.process_all_roots(&rootsCl,
3045                                      &cldCl,
3046                                      &blobsCl);
3047   }
3048 
3049   bool failures = rootsCl.failures() || codeRootsCl.failures();
3050 
3051   if (vo != VerifyOption_G1UseMarkWord) {
3052     // If we're verifying during a full GC then the region sets
3053     // will have been torn down at the start of the GC. Therefore
3054     // verifying the region sets will fail. So we only verify
3055     // the region sets when not in a full GC.
3056     log_debug(gc, verify)("HeapRegionSets");
3057     verify_region_sets();
3058   }
3059 
3060   log_debug(gc, verify)("HeapRegions");
3061   if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3062 
3063     G1ParVerifyTask task(this, vo);
3064     workers()->run_task(&task);
3065     if (task.failures()) {
3066       failures = true;
3067     }
3068 
3069   } else {
3070     VerifyRegionClosure blk(false, vo);
3071     heap_region_iterate(&blk);
3072     if (blk.failures()) {
3073       failures = true;
3074     }
3075   }
3076 
3077   if (G1StringDedup::is_enabled()) {
3078     log_debug(gc, verify)("StrDedup");
3079     G1StringDedup::verify();
3080   }
3081 
3082   if (failures) {
3083     log_info(gc, verify)("Heap after failed verification:");
3084     // It helps to have the per-region information in the output to
3085     // help us track down what went wrong. This is why we call
3086     // print_extended_on() instead of print_on().
3087     LogHandle(gc, verify) log;
3088     ResourceMark rm;
3089     print_extended_on(log.info_stream());
3090   }
3091   guarantee(!failures, "there should not have been any failures");
3092 }
3093 
3094 double G1CollectedHeap::verify(bool guard, const char* msg) {
3095   double verify_time_ms = 0.0;
3096 
3097   if (guard && total_collections() >= VerifyGCStartAt) {
3098     double verify_start = os::elapsedTime();
3099     HandleMark hm;  // Discard invalid handles created during verification
3100     prepare_for_verify();
3101     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3102     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3103   }
3104 
3105   return verify_time_ms;
3106 }
3107 
3108 void G1CollectedHeap::verify_before_gc() {
3109   double verify_time_ms = verify(VerifyBeforeGC, "Before GC");
3110   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3111 }
3112 
3113 void G1CollectedHeap::verify_after_gc() {
3114   double verify_time_ms = verify(VerifyAfterGC, "After GC");
3115   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3116 }
3117 
3118 class PrintRegionClosure: public HeapRegionClosure {
3119   outputStream* _st;
3120 public:
3121   PrintRegionClosure(outputStream* st) : _st(st) {}
3122   bool doHeapRegion(HeapRegion* r) {
3123     r->print_on(_st);
3124     return false;
3125   }
3126 };
3127 
3128 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3129                                        const HeapRegion* hr,
3130                                        const VerifyOption vo) const {
3131   switch (vo) {
3132   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3133   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3134   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
3135   default:                            ShouldNotReachHere();
3136   }
3137   return false; // keep some compilers happy
3138 }
3139 
3140 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3141                                        const VerifyOption vo) const {
3142   switch (vo) {
3143   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3144   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3145   case VerifyOption_G1UseMarkWord: {
3146     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3147     return !obj->is_gc_marked() && !hr->is_archive();
3148   }
3149   default:                            ShouldNotReachHere();
3150   }
3151   return false; // keep some compilers happy
3152 }
3153 
3154 void G1CollectedHeap::print_on(outputStream* st) const {
3155   st->print(" %-20s", "garbage-first heap");
3156   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3157             capacity()/K, used_unlocked()/K);
3158   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3159             p2i(_hrm.reserved().start()),
3160             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3161             p2i(_hrm.reserved().end()));
3162   st->cr();
3163   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3164   uint young_regions = _young_list->length();
3165   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3166             (size_t) young_regions * HeapRegion::GrainBytes / K);
3167   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3168   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3169             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3170   st->cr();
3171   MetaspaceAux::print_on(st);
3172 }
3173 
3174 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3175   print_on(st);
3176 
3177   // Print the per-region information.
3178   st->cr();
3179   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
3180                "HS=humongous(starts), HC=humongous(continues), "
3181                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3182                "AC=allocation context, "
3183                "TAMS=top-at-mark-start (previous, next)");
3184   PrintRegionClosure blk(st);
3185   heap_region_iterate(&blk);
3186 }
3187 
3188 void G1CollectedHeap::print_on_error(outputStream* st) const {
3189   this->CollectedHeap::print_on_error(st);
3190 
3191   if (_cm != NULL) {
3192     st->cr();
3193     _cm->print_on_error(st);
3194   }
3195 }
3196 
3197 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3198   workers()->print_worker_threads_on(st);
3199   _cmThread->print_on(st);
3200   st->cr();
3201   _cm->print_worker_threads_on(st);
3202   _cg1r->print_worker_threads_on(st);
3203   if (G1StringDedup::is_enabled()) {
3204     G1StringDedup::print_worker_threads_on(st);
3205   }
3206 }
3207 
3208 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3209   workers()->threads_do(tc);
3210   tc->do_thread(_cmThread);
3211   _cg1r->threads_do(tc);
3212   if (G1StringDedup::is_enabled()) {
3213     G1StringDedup::threads_do(tc);
3214   }
3215 }
3216 
3217 void G1CollectedHeap::print_tracing_info() const {
3218   // We'll overload this to mean "trace GC pause statistics."
3219   if (TraceYoungGenTime || TraceOldGenTime) {
3220     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3221     // to that.
3222     g1_policy()->print_tracing_info();
3223   }
3224   g1_rem_set()->print_summary_info();
3225   concurrent_mark()->print_summary_info();
3226   g1_policy()->print_yg_surv_rate_info();
3227 }
3228 
3229 #ifndef PRODUCT
3230 // Helpful for debugging RSet issues.
3231 
3232 class PrintRSetsClosure : public HeapRegionClosure {
3233 private:
3234   const char* _msg;
3235   size_t _occupied_sum;
3236 
3237 public:
3238   bool doHeapRegion(HeapRegion* r) {
3239     HeapRegionRemSet* hrrs = r->rem_set();
3240     size_t occupied = hrrs->occupied();
3241     _occupied_sum += occupied;
3242 
3243     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
3244     if (occupied == 0) {
3245       tty->print_cr("  RSet is empty");
3246     } else {
3247       hrrs->print();
3248     }
3249     tty->print_cr("----------");
3250     return false;
3251   }
3252 
3253   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3254     tty->cr();
3255     tty->print_cr("========================================");
3256     tty->print_cr("%s", msg);
3257     tty->cr();
3258   }
3259 
3260   ~PrintRSetsClosure() {
3261     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3262     tty->print_cr("========================================");
3263     tty->cr();
3264   }
3265 };
3266 
3267 void G1CollectedHeap::print_cset_rsets() {
3268   PrintRSetsClosure cl("Printing CSet RSets");
3269   collection_set_iterate(&cl);
3270 }
3271 
3272 void G1CollectedHeap::print_all_rsets() {
3273   PrintRSetsClosure cl("Printing All RSets");;
3274   heap_region_iterate(&cl);
3275 }
3276 #endif // PRODUCT
3277 
3278 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3279   YoungList* young_list = heap()->young_list();
3280 
3281   size_t eden_used_bytes = young_list->eden_used_bytes();
3282   size_t survivor_used_bytes = young_list->survivor_used_bytes();
3283 
3284   size_t eden_capacity_bytes =
3285     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3286 
3287   VirtualSpaceSummary heap_summary = create_heap_space_summary();
3288   return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3289 }
3290 
3291 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3292   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3293                        stats->unused(), stats->used(), stats->region_end_waste(),
3294                        stats->regions_filled(), stats->direct_allocated(),
3295                        stats->failure_used(), stats->failure_waste());
3296 }
3297 
3298 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3299   const G1HeapSummary& heap_summary = create_g1_heap_summary();
3300   gc_tracer->report_gc_heap_summary(when, heap_summary);
3301 
3302   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3303   gc_tracer->report_metaspace_summary(when, metaspace_summary);
3304 }
3305 
3306 
3307 G1CollectedHeap* G1CollectedHeap::heap() {
3308   CollectedHeap* heap = Universe::heap();
3309   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3310   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3311   return (G1CollectedHeap*)heap;
3312 }
3313 
3314 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3315   // always_do_update_barrier = false;
3316   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3317   // Fill TLAB's and such
3318   accumulate_statistics_all_tlabs();
3319   ensure_parsability(true);
3320 
3321   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
3322 }
3323 
3324 void G1CollectedHeap::gc_epilogue(bool full) {
3325   // we are at the end of the GC. Total collections has already been increased.
3326   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
3327 
3328   // FIXME: what is this about?
3329   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3330   // is set.
3331 #if defined(COMPILER2) || INCLUDE_JVMCI
3332   assert(DerivedPointerTable::is_empty(), "derived pointer present");
3333 #endif
3334   // always_do_update_barrier = true;
3335 
3336   resize_all_tlabs();
3337   allocation_context_stats().update(full);
3338 
3339   // We have just completed a GC. Update the soft reference
3340   // policy with the new heap occupancy
3341   Universe::update_heap_info_at_gc();
3342 }
3343 
3344 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3345                                                uint gc_count_before,
3346                                                bool* succeeded,
3347                                                GCCause::Cause gc_cause) {
3348   assert_heap_not_locked_and_not_at_safepoint();
3349   g1_policy()->record_stop_world_start();
3350   VM_G1IncCollectionPause op(gc_count_before,
3351                              word_size,
3352                              false, /* should_initiate_conc_mark */
3353                              g1_policy()->max_pause_time_ms(),
3354                              gc_cause);
3355 
3356   op.set_allocation_context(AllocationContext::current());
3357   VMThread::execute(&op);
3358 
3359   HeapWord* result = op.result();
3360   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3361   assert(result == NULL || ret_succeeded,
3362          "the result should be NULL if the VM did not succeed");
3363   *succeeded = ret_succeeded;
3364 
3365   assert_heap_not_locked();
3366   return result;
3367 }
3368 
3369 void
3370 G1CollectedHeap::doConcurrentMark() {
3371   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3372   if (!_cmThread->in_progress()) {
3373     _cmThread->set_started();
3374     CGC_lock->notify();
3375   }
3376 }
3377 
3378 size_t G1CollectedHeap::pending_card_num() {
3379   size_t extra_cards = 0;
3380   JavaThread *curr = Threads::first();
3381   while (curr != NULL) {
3382     DirtyCardQueue& dcq = curr->dirty_card_queue();
3383     extra_cards += dcq.size();
3384     curr = curr->next();
3385   }
3386   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3387   size_t buffer_size = dcqs.buffer_size();
3388   size_t buffer_num = dcqs.completed_buffers_num();
3389 
3390   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3391   // in bytes - not the number of 'entries'. We need to convert
3392   // into a number of cards.
3393   return (buffer_size * buffer_num + extra_cards) / oopSize;
3394 }
3395 
3396 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3397  private:
3398   size_t _total_humongous;
3399   size_t _candidate_humongous;
3400 
3401   DirtyCardQueue _dcq;
3402 
3403   // We don't nominate objects with many remembered set entries, on
3404   // the assumption that such objects are likely still live.
3405   bool is_remset_small(HeapRegion* region) const {
3406     HeapRegionRemSet* const rset = region->rem_set();
3407     return G1EagerReclaimHumongousObjectsWithStaleRefs
3408       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3409       : rset->is_empty();
3410   }
3411 
3412   bool is_typeArray_region(HeapRegion* region) const {
3413     return oop(region->bottom())->is_typeArray();
3414   }
3415 
3416   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3417     assert(region->is_starts_humongous(), "Must start a humongous object");
3418 
3419     // Candidate selection must satisfy the following constraints
3420     // while concurrent marking is in progress:
3421     //
3422     // * In order to maintain SATB invariants, an object must not be
3423     // reclaimed if it was allocated before the start of marking and
3424     // has not had its references scanned.  Such an object must have
3425     // its references (including type metadata) scanned to ensure no
3426     // live objects are missed by the marking process.  Objects
3427     // allocated after the start of concurrent marking don't need to
3428     // be scanned.
3429     //
3430     // * An object must not be reclaimed if it is on the concurrent
3431     // mark stack.  Objects allocated after the start of concurrent
3432     // marking are never pushed on the mark stack.
3433     //
3434     // Nominating only objects allocated after the start of concurrent
3435     // marking is sufficient to meet both constraints.  This may miss
3436     // some objects that satisfy the constraints, but the marking data
3437     // structures don't support efficiently performing the needed
3438     // additional tests or scrubbing of the mark stack.
3439     //
3440     // However, we presently only nominate is_typeArray() objects.
3441     // A humongous object containing references induces remembered
3442     // set entries on other regions.  In order to reclaim such an
3443     // object, those remembered sets would need to be cleaned up.
3444     //
3445     // We also treat is_typeArray() objects specially, allowing them
3446     // to be reclaimed even if allocated before the start of
3447     // concurrent mark.  For this we rely on mark stack insertion to
3448     // exclude is_typeArray() objects, preventing reclaiming an object
3449     // that is in the mark stack.  We also rely on the metadata for
3450     // such objects to be built-in and so ensured to be kept live.
3451     // Frequent allocation and drop of large binary blobs is an
3452     // important use case for eager reclaim, and this special handling
3453     // may reduce needed headroom.
3454 
3455     return is_typeArray_region(region) && is_remset_small(region);
3456   }
3457 
3458  public:
3459   RegisterHumongousWithInCSetFastTestClosure()
3460   : _total_humongous(0),
3461     _candidate_humongous(0),
3462     _dcq(&JavaThread::dirty_card_queue_set()) {
3463   }
3464 
3465   virtual bool doHeapRegion(HeapRegion* r) {
3466     if (!r->is_starts_humongous()) {
3467       return false;
3468     }
3469     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3470 
3471     bool is_candidate = humongous_region_is_candidate(g1h, r);
3472     uint rindex = r->hrm_index();
3473     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3474     if (is_candidate) {
3475       _candidate_humongous++;
3476       g1h->register_humongous_region_with_cset(rindex);
3477       // Is_candidate already filters out humongous object with large remembered sets.
3478       // If we have a humongous object with a few remembered sets, we simply flush these
3479       // remembered set entries into the DCQS. That will result in automatic
3480       // re-evaluation of their remembered set entries during the following evacuation
3481       // phase.
3482       if (!r->rem_set()->is_empty()) {
3483         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3484                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3485         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3486         HeapRegionRemSetIterator hrrs(r->rem_set());
3487         size_t card_index;
3488         while (hrrs.has_next(card_index)) {
3489           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3490           // The remembered set might contain references to already freed
3491           // regions. Filter out such entries to avoid failing card table
3492           // verification.
3493           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3494             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3495               *card_ptr = CardTableModRefBS::dirty_card_val();
3496               _dcq.enqueue(card_ptr);
3497             }
3498           }
3499         }
3500         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3501                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3502                hrrs.n_yielded(), r->rem_set()->occupied());
3503         r->rem_set()->clear_locked();
3504       }
3505       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3506     }
3507     _total_humongous++;
3508 
3509     return false;
3510   }
3511 
3512   size_t total_humongous() const { return _total_humongous; }
3513   size_t candidate_humongous() const { return _candidate_humongous; }
3514 
3515   void flush_rem_set_entries() { _dcq.flush(); }
3516 };
3517 
3518 void G1CollectedHeap::register_humongous_regions_with_cset() {
3519   if (!G1EagerReclaimHumongousObjects) {
3520     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3521     return;
3522   }
3523   double time = os::elapsed_counter();
3524 
3525   // Collect reclaim candidate information and register candidates with cset.
3526   RegisterHumongousWithInCSetFastTestClosure cl;
3527   heap_region_iterate(&cl);
3528 
3529   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3530   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3531                                                                   cl.total_humongous(),
3532                                                                   cl.candidate_humongous());
3533   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3534 
3535   // Finally flush all remembered set entries to re-check into the global DCQS.
3536   cl.flush_rem_set_entries();
3537 }
3538 
3539 class VerifyRegionRemSetClosure : public HeapRegionClosure {
3540   public:
3541     bool doHeapRegion(HeapRegion* hr) {
3542       if (!hr->is_archive() && !hr->is_continues_humongous()) {
3543         hr->verify_rem_set();
3544       }
3545       return false;
3546     }
3547 };
3548 
3549 #ifdef ASSERT
3550 class VerifyCSetClosure: public HeapRegionClosure {
3551 public:
3552   bool doHeapRegion(HeapRegion* hr) {
3553     // Here we check that the CSet region's RSet is ready for parallel
3554     // iteration. The fields that we'll verify are only manipulated
3555     // when the region is part of a CSet and is collected. Afterwards,
3556     // we reset these fields when we clear the region's RSet (when the
3557     // region is freed) so they are ready when the region is
3558     // re-allocated. The only exception to this is if there's an
3559     // evacuation failure and instead of freeing the region we leave
3560     // it in the heap. In that case, we reset these fields during
3561     // evacuation failure handling.
3562     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3563 
3564     // Here's a good place to add any other checks we'd like to
3565     // perform on CSet regions.
3566     return false;
3567   }
3568 };
3569 #endif // ASSERT
3570 
3571 uint G1CollectedHeap::num_task_queues() const {
3572   return _task_queues->size();
3573 }
3574 
3575 #if TASKQUEUE_STATS
3576 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3577   st->print_raw_cr("GC Task Stats");
3578   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3579   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3580 }
3581 
3582 void G1CollectedHeap::print_taskqueue_stats() const {
3583   if (!develop_log_is_enabled(Trace, gc, task, stats)) {
3584     return;
3585   }
3586   LogHandle(gc, task, stats) log;
3587   ResourceMark rm;
3588   outputStream* st = log.trace_stream();
3589 
3590   print_taskqueue_stats_hdr(st);
3591 
3592   TaskQueueStats totals;
3593   const uint n = num_task_queues();
3594   for (uint i = 0; i < n; ++i) {
3595     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3596     totals += task_queue(i)->stats;
3597   }
3598   st->print_raw("tot "); totals.print(st); st->cr();
3599 
3600   DEBUG_ONLY(totals.verify());
3601 }
3602 
3603 void G1CollectedHeap::reset_taskqueue_stats() {
3604   const uint n = num_task_queues();
3605   for (uint i = 0; i < n; ++i) {
3606     task_queue(i)->stats.reset();
3607   }
3608 }
3609 #endif // TASKQUEUE_STATS
3610 
3611 void G1CollectedHeap::log_gc_footer(jlong pause_time_counter) {
3612   if (evacuation_failed()) {
3613     log_info(gc)("To-space exhausted");
3614   }
3615 
3616   double pause_time_ms = TimeHelper::counter_to_millis(pause_time_counter);
3617   g1_policy()->print_phases(pause_time_ms);
3618 
3619   g1_policy()->print_detailed_heap_transition();
3620 }
3621 
3622 
3623 void G1CollectedHeap::wait_for_root_region_scanning() {
3624   double scan_wait_start = os::elapsedTime();
3625   // We have to wait until the CM threads finish scanning the
3626   // root regions as it's the only way to ensure that all the
3627   // objects on them have been correctly scanned before we start
3628   // moving them during the GC.
3629   bool waited = _cm->root_regions()->wait_until_scan_finished();
3630   double wait_time_ms = 0.0;
3631   if (waited) {
3632     double scan_wait_end = os::elapsedTime();
3633     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3634   }
3635   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3636 }
3637 
3638 bool
3639 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3640   assert_at_safepoint(true /* should_be_vm_thread */);
3641   guarantee(!is_gc_active(), "collection is not reentrant");
3642 
3643   if (GCLocker::check_active_before_gc()) {
3644     return false;
3645   }
3646 
3647   _gc_timer_stw->register_gc_start();
3648 
3649   GCIdMark gc_id_mark;
3650   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3651 
3652   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3653   ResourceMark rm;
3654 
3655   wait_for_root_region_scanning();
3656 
3657   print_heap_before_gc();
3658   trace_heap_before_gc(_gc_tracer_stw);
3659 
3660   verify_region_sets_optional();
3661   verify_dirty_young_regions();
3662 
3663   // This call will decide whether this pause is an initial-mark
3664   // pause. If it is, during_initial_mark_pause() will return true
3665   // for the duration of this pause.
3666   g1_policy()->decide_on_conc_mark_initiation();
3667 
3668   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3669   assert(!collector_state()->during_initial_mark_pause() ||
3670           collector_state()->gcs_are_young(), "sanity");
3671 
3672   // We also do not allow mixed GCs during marking.
3673   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3674 
3675   // Record whether this pause is an initial mark. When the current
3676   // thread has completed its logging output and it's safe to signal
3677   // the CM thread, the flag's value in the policy has been reset.
3678   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3679 
3680   // Inner scope for scope based logging, timers, and stats collection
3681   {
3682     EvacuationInfo evacuation_info;
3683 
3684     if (collector_state()->during_initial_mark_pause()) {
3685       // We are about to start a marking cycle, so we increment the
3686       // full collection counter.
3687       increment_old_marking_cycles_started();
3688       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3689     }
3690 
3691     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3692 
3693     GCTraceCPUTime tcpu;
3694 
3695     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3696                                                                   workers()->active_workers(),
3697                                                                   Threads::number_of_non_daemon_threads());
3698     workers()->set_active_workers(active_workers);
3699     FormatBuffer<> gc_string("Pause ");
3700     if (collector_state()->during_initial_mark_pause()) {
3701       gc_string.append("Initial Mark");
3702     } else if (collector_state()->gcs_are_young()) {
3703       gc_string.append("Young");
3704     } else {
3705       gc_string.append("Mixed");
3706     }
3707     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3708 
3709     jlong pause_start_counter = os::elapsed_counter();
3710     g1_policy()->note_gc_start(active_workers);
3711 
3712     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3713     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3714 
3715     // If the secondary_free_list is not empty, append it to the
3716     // free_list. No need to wait for the cleanup operation to finish;
3717     // the region allocation code will check the secondary_free_list
3718     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3719     // set, skip this step so that the region allocation code has to
3720     // get entries from the secondary_free_list.
3721     if (!G1StressConcRegionFreeing) {
3722       append_secondary_free_list_if_not_empty_with_lock();
3723     }
3724 
3725     assert(check_young_list_well_formed(), "young list should be well formed");
3726 
3727     // Don't dynamically change the number of GC threads this early.  A value of
3728     // 0 is used to indicate serial work.  When parallel work is done,
3729     // it will be set.
3730 
3731     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3732       IsGCActiveMark x;
3733 
3734       gc_prologue(false);
3735       increment_total_collections(false /* full gc */);
3736       increment_gc_time_stamp();
3737 
3738       if (VerifyRememberedSets) {
3739         log_info(gc, verify)("[Verifying RemSets before GC]");
3740         VerifyRegionRemSetClosure v_cl;
3741         heap_region_iterate(&v_cl);
3742       }
3743 
3744       verify_before_gc();
3745 
3746       check_bitmaps("GC Start");
3747 
3748 #if defined(COMPILER2) || INCLUDE_JVMCI
3749       DerivedPointerTable::clear();
3750 #endif
3751 
3752       // Please see comment in g1CollectedHeap.hpp and
3753       // G1CollectedHeap::ref_processing_init() to see how
3754       // reference processing currently works in G1.
3755 
3756       // Enable discovery in the STW reference processor
3757       if (g1_policy()->should_process_references()) {
3758         ref_processor_stw()->enable_discovery();
3759       } else {
3760         ref_processor_stw()->disable_discovery();
3761       }
3762 
3763       {
3764         // We want to temporarily turn off discovery by the
3765         // CM ref processor, if necessary, and turn it back on
3766         // on again later if we do. Using a scoped
3767         // NoRefDiscovery object will do this.
3768         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3769 
3770         // Forget the current alloc region (we might even choose it to be part
3771         // of the collection set!).
3772         _allocator->release_mutator_alloc_region();
3773 
3774         // This timing is only used by the ergonomics to handle our pause target.
3775         // It is unclear why this should not include the full pause. We will
3776         // investigate this in CR 7178365.
3777         //
3778         // Preserving the old comment here if that helps the investigation:
3779         //
3780         // The elapsed time induced by the start time below deliberately elides
3781         // the possible verification above.
3782         double sample_start_time_sec = os::elapsedTime();
3783 
3784         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3785 
3786         if (collector_state()->during_initial_mark_pause()) {
3787           concurrent_mark()->checkpointRootsInitialPre();
3788         }
3789 
3790         double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3791         g1_policy()->finalize_old_cset_part(time_remaining_ms);
3792 
3793         evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3794 
3795         // Make sure the remembered sets are up to date. This needs to be
3796         // done before register_humongous_regions_with_cset(), because the
3797         // remembered sets are used there to choose eager reclaim candidates.
3798         // If the remembered sets are not up to date we might miss some
3799         // entries that need to be handled.
3800         g1_rem_set()->cleanupHRRS();
3801 
3802         register_humongous_regions_with_cset();
3803 
3804         assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3805 
3806         _cm->note_start_of_gc();
3807         // We call this after finalize_cset() to
3808         // ensure that the CSet has been finalized.
3809         _cm->verify_no_cset_oops();
3810 
3811         if (_hr_printer.is_active()) {
3812           HeapRegion* hr = g1_policy()->collection_set();
3813           while (hr != NULL) {
3814             _hr_printer.cset(hr);
3815             hr = hr->next_in_collection_set();
3816           }
3817         }
3818 
3819 #ifdef ASSERT
3820         VerifyCSetClosure cl;
3821         collection_set_iterate(&cl);
3822 #endif // ASSERT
3823 
3824         // Initialize the GC alloc regions.
3825         _allocator->init_gc_alloc_regions(evacuation_info);
3826 
3827         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3828         pre_evacuate_collection_set();
3829 
3830         // Actually do the work...
3831         evacuate_collection_set(evacuation_info, &per_thread_states);
3832 
3833         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3834 
3835         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3836         free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3837 
3838         eagerly_reclaim_humongous_regions();
3839 
3840         g1_policy()->clear_collection_set();
3841 
3842         // Start a new incremental collection set for the next pause.
3843         g1_policy()->start_incremental_cset_building();
3844 
3845         clear_cset_fast_test();
3846 
3847         _young_list->reset_sampled_info();
3848 
3849         // Don't check the whole heap at this point as the
3850         // GC alloc regions from this pause have been tagged
3851         // as survivors and moved on to the survivor list.
3852         // Survivor regions will fail the !is_young() check.
3853         assert(check_young_list_empty(false /* check_heap */),
3854           "young list should be empty");
3855 
3856         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3857                                              _young_list->first_survivor_region(),
3858                                              _young_list->last_survivor_region());
3859 
3860         _young_list->reset_auxilary_lists();
3861 
3862         if (evacuation_failed()) {
3863           set_used(recalculate_used());
3864           if (_archive_allocator != NULL) {
3865             _archive_allocator->clear_used();
3866           }
3867           for (uint i = 0; i < ParallelGCThreads; i++) {
3868             if (_evacuation_failed_info_array[i].has_failed()) {
3869               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3870             }
3871           }
3872         } else {
3873           // The "used" of the the collection set have already been subtracted
3874           // when they were freed.  Add in the bytes evacuated.
3875           increase_used(g1_policy()->bytes_copied_during_gc());
3876         }
3877 
3878         if (collector_state()->during_initial_mark_pause()) {
3879           // We have to do this before we notify the CM threads that
3880           // they can start working to make sure that all the
3881           // appropriate initialization is done on the CM object.
3882           concurrent_mark()->checkpointRootsInitialPost();
3883           collector_state()->set_mark_in_progress(true);
3884           // Note that we don't actually trigger the CM thread at
3885           // this point. We do that later when we're sure that
3886           // the current thread has completed its logging output.
3887         }
3888 
3889         allocate_dummy_regions();
3890 
3891         _allocator->init_mutator_alloc_region();
3892 
3893         {
3894           size_t expand_bytes = g1_policy()->expansion_amount();
3895           if (expand_bytes > 0) {
3896             size_t bytes_before = capacity();
3897             // No need for an ergo logging here,
3898             // expansion_amount() does this when it returns a value > 0.
3899             double expand_ms;
3900             if (!expand(expand_bytes, &expand_ms)) {
3901               // We failed to expand the heap. Cannot do anything about it.
3902             }
3903             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3904           }
3905         }
3906 
3907         // We redo the verification but now wrt to the new CSet which
3908         // has just got initialized after the previous CSet was freed.
3909         _cm->verify_no_cset_oops();
3910         _cm->note_end_of_gc();
3911 
3912         // This timing is only used by the ergonomics to handle our pause target.
3913         // It is unclear why this should not include the full pause. We will
3914         // investigate this in CR 7178365.
3915         double sample_end_time_sec = os::elapsedTime();
3916         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3917         size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3918         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3919 
3920         evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3921         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3922 
3923         MemoryService::track_memory_usage();
3924 
3925         // In prepare_for_verify() below we'll need to scan the deferred
3926         // update buffers to bring the RSets up-to-date if
3927         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3928         // the update buffers we'll probably need to scan cards on the
3929         // regions we just allocated to (i.e., the GC alloc
3930         // regions). However, during the last GC we called
3931         // set_saved_mark() on all the GC alloc regions, so card
3932         // scanning might skip the [saved_mark_word()...top()] area of
3933         // those regions (i.e., the area we allocated objects into
3934         // during the last GC). But it shouldn't. Given that
3935         // saved_mark_word() is conditional on whether the GC time stamp
3936         // on the region is current or not, by incrementing the GC time
3937         // stamp here we invalidate all the GC time stamps on all the
3938         // regions and saved_mark_word() will simply return top() for
3939         // all the regions. This is a nicer way of ensuring this rather
3940         // than iterating over the regions and fixing them. In fact, the
3941         // GC time stamp increment here also ensures that
3942         // saved_mark_word() will return top() between pauses, i.e.,
3943         // during concurrent refinement. So we don't need the
3944         // is_gc_active() check to decided which top to use when
3945         // scanning cards (see CR 7039627).
3946         increment_gc_time_stamp();
3947 
3948         if (VerifyRememberedSets) {
3949           log_info(gc, verify)("[Verifying RemSets after GC]");
3950           VerifyRegionRemSetClosure v_cl;
3951           heap_region_iterate(&v_cl);
3952         }
3953 
3954         verify_after_gc();
3955         check_bitmaps("GC End");
3956 
3957         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3958         ref_processor_stw()->verify_no_references_recorded();
3959 
3960         // CM reference discovery will be re-enabled if necessary.
3961       }
3962 
3963 #ifdef TRACESPINNING
3964       ParallelTaskTerminator::print_termination_counts();
3965 #endif
3966 
3967       gc_epilogue(false);
3968     }
3969 
3970     // Print the remainder of the GC log output.
3971     log_gc_footer(os::elapsed_counter() - pause_start_counter);
3972 
3973     // It is not yet to safe to tell the concurrent mark to
3974     // start as we have some optional output below. We don't want the
3975     // output from the concurrent mark thread interfering with this
3976     // logging output either.
3977 
3978     _hrm.verify_optional();
3979     verify_region_sets_optional();
3980 
3981     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3982     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3983 
3984     print_heap_after_gc();
3985     trace_heap_after_gc(_gc_tracer_stw);
3986 
3987     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3988     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3989     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3990     // before any GC notifications are raised.
3991     g1mm()->update_sizes();
3992 
3993     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3994     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3995     _gc_timer_stw->register_gc_end();
3996     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3997   }
3998   // It should now be safe to tell the concurrent mark thread to start
3999   // without its logging output interfering with the logging output
4000   // that came from the pause.
4001 
4002   if (should_start_conc_mark) {
4003     // CAUTION: after the doConcurrentMark() call below,
4004     // the concurrent marking thread(s) could be running
4005     // concurrently with us. Make sure that anything after
4006     // this point does not assume that we are the only GC thread
4007     // running. Note: of course, the actual marking work will
4008     // not start until the safepoint itself is released in
4009     // SuspendibleThreadSet::desynchronize().
4010     doConcurrentMark();
4011   }
4012 
4013   return true;
4014 }
4015 
4016 void G1CollectedHeap::restore_preserved_marks() {
4017   G1RestorePreservedMarksTask rpm_task(_preserved_objs);
4018   workers()->run_task(&rpm_task);
4019 }
4020 
4021 void G1CollectedHeap::remove_self_forwarding_pointers() {
4022   G1ParRemoveSelfForwardPtrsTask rsfp_task;
4023   workers()->run_task(&rsfp_task);
4024 }
4025 
4026 void G1CollectedHeap::restore_after_evac_failure() {
4027   double remove_self_forwards_start = os::elapsedTime();
4028 
4029   remove_self_forwarding_pointers();
4030   restore_preserved_marks();
4031 
4032   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4033 }
4034 
4035 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4036   if (!_evacuation_failed) {
4037     _evacuation_failed = true;
4038   }
4039 
4040   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4041 
4042   // We want to call the "for_promotion_failure" version only in the
4043   // case of a promotion failure.
4044   if (m->must_be_preserved_for_promotion_failure(obj)) {
4045     OopAndMarkOop elem(obj, m);
4046     _preserved_objs[worker_id].push(elem);
4047   }
4048 }
4049 
4050 bool G1ParEvacuateFollowersClosure::offer_termination() {
4051   G1ParScanThreadState* const pss = par_scan_state();
4052   start_term_time();
4053   const bool res = terminator()->offer_termination();
4054   end_term_time();
4055   return res;
4056 }
4057 
4058 void G1ParEvacuateFollowersClosure::do_void() {
4059   G1ParScanThreadState* const pss = par_scan_state();
4060   pss->trim_queue();
4061   do {
4062     pss->steal_and_trim_queue(queues());
4063   } while (!offer_termination());
4064 }
4065 
4066 class G1ParTask : public AbstractGangTask {
4067 protected:
4068   G1CollectedHeap*         _g1h;
4069   G1ParScanThreadStateSet* _pss;
4070   RefToScanQueueSet*       _queues;
4071   G1RootProcessor*         _root_processor;
4072   ParallelTaskTerminator   _terminator;
4073   uint                     _n_workers;
4074 
4075 public:
4076   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4077     : AbstractGangTask("G1 collection"),
4078       _g1h(g1h),
4079       _pss(per_thread_states),
4080       _queues(task_queues),
4081       _root_processor(root_processor),
4082       _terminator(n_workers, _queues),
4083       _n_workers(n_workers)
4084   {}
4085 
4086   void work(uint worker_id) {
4087     if (worker_id >= _n_workers) return;  // no work needed this round
4088 
4089     double start_sec = os::elapsedTime();
4090     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4091 
4092     {
4093       ResourceMark rm;
4094       HandleMark   hm;
4095 
4096       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4097 
4098       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
4099       pss->set_ref_processor(rp);
4100 
4101       double start_strong_roots_sec = os::elapsedTime();
4102 
4103       _root_processor->evacuate_roots(pss->closures(), worker_id);
4104 
4105       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4106 
4107       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4108       // treating the nmethods visited to act as roots for concurrent marking.
4109       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4110       // objects copied by the current evacuation.
4111       size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4112                                                                              pss->closures()->weak_codeblobs(),
4113                                                                              worker_id);
4114 
4115       _pss->add_cards_scanned(worker_id, cards_scanned);
4116 
4117       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4118 
4119       double term_sec = 0.0;
4120       size_t evac_term_attempts = 0;
4121       {
4122         double start = os::elapsedTime();
4123         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4124         evac.do_void();
4125 
4126         evac_term_attempts = evac.term_attempts();
4127         term_sec = evac.term_time();
4128         double elapsed_sec = os::elapsedTime() - start;
4129         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4130         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4131         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4132       }
4133 
4134       assert(pss->queue_is_empty(), "should be empty");
4135 
4136       if (log_is_enabled(Debug, gc, task, stats)) {
4137         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4138         size_t lab_waste;
4139         size_t lab_undo_waste;
4140         pss->waste(lab_waste, lab_undo_waste);
4141         _g1h->print_termination_stats(worker_id,
4142                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
4143                                       strong_roots_sec * 1000.0,                  /* strong roots time */
4144                                       term_sec * 1000.0,                          /* evac term time */
4145                                       evac_term_attempts,                         /* evac term attempts */
4146                                       lab_waste,                                  /* alloc buffer waste */
4147                                       lab_undo_waste                              /* undo waste */
4148                                       );
4149       }
4150 
4151       // Close the inner scope so that the ResourceMark and HandleMark
4152       // destructors are executed here and are included as part of the
4153       // "GC Worker Time".
4154     }
4155     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4156   }
4157 };
4158 
4159 void G1CollectedHeap::print_termination_stats_hdr() {
4160   log_debug(gc, task, stats)("GC Termination Stats");
4161   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
4162   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
4163   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4164 }
4165 
4166 void G1CollectedHeap::print_termination_stats(uint worker_id,
4167                                               double elapsed_ms,
4168                                               double strong_roots_ms,
4169                                               double term_ms,
4170                                               size_t term_attempts,
4171                                               size_t alloc_buffer_waste,
4172                                               size_t undo_waste) const {
4173   log_debug(gc, task, stats)
4174               ("%3d %9.2f %9.2f %6.2f "
4175                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4176                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4177                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4178                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4179                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4180                alloc_buffer_waste * HeapWordSize / K,
4181                undo_waste * HeapWordSize / K);
4182 }
4183 
4184 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4185 private:
4186   BoolObjectClosure* _is_alive;
4187   int _initial_string_table_size;
4188   int _initial_symbol_table_size;
4189 
4190   bool  _process_strings;
4191   int _strings_processed;
4192   int _strings_removed;
4193 
4194   bool  _process_symbols;
4195   int _symbols_processed;
4196   int _symbols_removed;
4197 
4198 public:
4199   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4200     AbstractGangTask("String/Symbol Unlinking"),
4201     _is_alive(is_alive),
4202     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4203     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4204 
4205     _initial_string_table_size = StringTable::the_table()->table_size();
4206     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4207     if (process_strings) {
4208       StringTable::clear_parallel_claimed_index();
4209     }
4210     if (process_symbols) {
4211       SymbolTable::clear_parallel_claimed_index();
4212     }
4213   }
4214 
4215   ~G1StringSymbolTableUnlinkTask() {
4216     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4217               "claim value %d after unlink less than initial string table size %d",
4218               StringTable::parallel_claimed_index(), _initial_string_table_size);
4219     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4220               "claim value %d after unlink less than initial symbol table size %d",
4221               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4222 
4223     log_debug(gc, stringdedup)("Cleaned string and symbol table, "
4224                                "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4225                                "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4226                                strings_processed(), strings_removed(),
4227                                symbols_processed(), symbols_removed());
4228   }
4229 
4230   void work(uint worker_id) {
4231     int strings_processed = 0;
4232     int strings_removed = 0;
4233     int symbols_processed = 0;
4234     int symbols_removed = 0;
4235     if (_process_strings) {
4236       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4237       Atomic::add(strings_processed, &_strings_processed);
4238       Atomic::add(strings_removed, &_strings_removed);
4239     }
4240     if (_process_symbols) {
4241       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4242       Atomic::add(symbols_processed, &_symbols_processed);
4243       Atomic::add(symbols_removed, &_symbols_removed);
4244     }
4245   }
4246 
4247   size_t strings_processed() const { return (size_t)_strings_processed; }
4248   size_t strings_removed()   const { return (size_t)_strings_removed; }
4249 
4250   size_t symbols_processed() const { return (size_t)_symbols_processed; }
4251   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
4252 };
4253 
4254 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4255 private:
4256   static Monitor* _lock;
4257 
4258   BoolObjectClosure* const _is_alive;
4259   const bool               _unloading_occurred;
4260   const uint               _num_workers;
4261 
4262   // Variables used to claim nmethods.
4263   nmethod* _first_nmethod;
4264   volatile nmethod* _claimed_nmethod;
4265 
4266   // The list of nmethods that need to be processed by the second pass.
4267   volatile nmethod* _postponed_list;
4268   volatile uint     _num_entered_barrier;
4269 
4270  public:
4271   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4272       _is_alive(is_alive),
4273       _unloading_occurred(unloading_occurred),
4274       _num_workers(num_workers),
4275       _first_nmethod(NULL),
4276       _claimed_nmethod(NULL),
4277       _postponed_list(NULL),
4278       _num_entered_barrier(0)
4279   {
4280     nmethod::increase_unloading_clock();
4281     // Get first alive nmethod
4282     NMethodIterator iter = NMethodIterator();
4283     if(iter.next_alive()) {
4284       _first_nmethod = iter.method();
4285     }
4286     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4287   }
4288 
4289   ~G1CodeCacheUnloadingTask() {
4290     CodeCache::verify_clean_inline_caches();
4291 
4292     CodeCache::set_needs_cache_clean(false);
4293     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4294 
4295     CodeCache::verify_icholder_relocations();
4296   }
4297 
4298  private:
4299   void add_to_postponed_list(nmethod* nm) {
4300       nmethod* old;
4301       do {
4302         old = (nmethod*)_postponed_list;
4303         nm->set_unloading_next(old);
4304       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4305   }
4306 
4307   void clean_nmethod(nmethod* nm) {
4308     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4309 
4310     if (postponed) {
4311       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4312       add_to_postponed_list(nm);
4313     }
4314 
4315     // Mark that this thread has been cleaned/unloaded.
4316     // After this call, it will be safe to ask if this nmethod was unloaded or not.
4317     nm->set_unloading_clock(nmethod::global_unloading_clock());
4318   }
4319 
4320   void clean_nmethod_postponed(nmethod* nm) {
4321     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4322   }
4323 
4324   static const int MaxClaimNmethods = 16;
4325 
4326   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4327     nmethod* first;
4328     NMethodIterator last;
4329 
4330     do {
4331       *num_claimed_nmethods = 0;
4332 
4333       first = (nmethod*)_claimed_nmethod;
4334       last = NMethodIterator(first);
4335 
4336       if (first != NULL) {
4337 
4338         for (int i = 0; i < MaxClaimNmethods; i++) {
4339           if (!last.next_alive()) {
4340             break;
4341           }
4342           claimed_nmethods[i] = last.method();
4343           (*num_claimed_nmethods)++;
4344         }
4345       }
4346 
4347     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4348   }
4349 
4350   nmethod* claim_postponed_nmethod() {
4351     nmethod* claim;
4352     nmethod* next;
4353 
4354     do {
4355       claim = (nmethod*)_postponed_list;
4356       if (claim == NULL) {
4357         return NULL;
4358       }
4359 
4360       next = claim->unloading_next();
4361 
4362     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4363 
4364     return claim;
4365   }
4366 
4367  public:
4368   // Mark that we're done with the first pass of nmethod cleaning.
4369   void barrier_mark(uint worker_id) {
4370     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4371     _num_entered_barrier++;
4372     if (_num_entered_barrier == _num_workers) {
4373       ml.notify_all();
4374     }
4375   }
4376 
4377   // See if we have to wait for the other workers to
4378   // finish their first-pass nmethod cleaning work.
4379   void barrier_wait(uint worker_id) {
4380     if (_num_entered_barrier < _num_workers) {
4381       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4382       while (_num_entered_barrier < _num_workers) {
4383           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4384       }
4385     }
4386   }
4387 
4388   // Cleaning and unloading of nmethods. Some work has to be postponed
4389   // to the second pass, when we know which nmethods survive.
4390   void work_first_pass(uint worker_id) {
4391     // The first nmethods is claimed by the first worker.
4392     if (worker_id == 0 && _first_nmethod != NULL) {
4393       clean_nmethod(_first_nmethod);
4394       _first_nmethod = NULL;
4395     }
4396 
4397     int num_claimed_nmethods;
4398     nmethod* claimed_nmethods[MaxClaimNmethods];
4399 
4400     while (true) {
4401       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4402 
4403       if (num_claimed_nmethods == 0) {
4404         break;
4405       }
4406 
4407       for (int i = 0; i < num_claimed_nmethods; i++) {
4408         clean_nmethod(claimed_nmethods[i]);
4409       }
4410     }
4411   }
4412 
4413   void work_second_pass(uint worker_id) {
4414     nmethod* nm;
4415     // Take care of postponed nmethods.
4416     while ((nm = claim_postponed_nmethod()) != NULL) {
4417       clean_nmethod_postponed(nm);
4418     }
4419   }
4420 };
4421 
4422 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4423 
4424 class G1KlassCleaningTask : public StackObj {
4425   BoolObjectClosure*                      _is_alive;
4426   volatile jint                           _clean_klass_tree_claimed;
4427   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4428 
4429  public:
4430   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4431       _is_alive(is_alive),
4432       _clean_klass_tree_claimed(0),
4433       _klass_iterator() {
4434   }
4435 
4436  private:
4437   bool claim_clean_klass_tree_task() {
4438     if (_clean_klass_tree_claimed) {
4439       return false;
4440     }
4441 
4442     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4443   }
4444 
4445   InstanceKlass* claim_next_klass() {
4446     Klass* klass;
4447     do {
4448       klass =_klass_iterator.next_klass();
4449     } while (klass != NULL && !klass->is_instance_klass());
4450 
4451     // this can be null so don't call InstanceKlass::cast
4452     return static_cast<InstanceKlass*>(klass);
4453   }
4454 
4455 public:
4456 
4457   void clean_klass(InstanceKlass* ik) {
4458     ik->clean_weak_instanceklass_links(_is_alive);
4459   }
4460 
4461   void work() {
4462     ResourceMark rm;
4463 
4464     // One worker will clean the subklass/sibling klass tree.
4465     if (claim_clean_klass_tree_task()) {
4466       Klass::clean_subklass_tree(_is_alive);
4467     }
4468 
4469     // All workers will help cleaning the classes,
4470     InstanceKlass* klass;
4471     while ((klass = claim_next_klass()) != NULL) {
4472       clean_klass(klass);
4473     }
4474   }
4475 };
4476 
4477 // To minimize the remark pause times, the tasks below are done in parallel.
4478 class G1ParallelCleaningTask : public AbstractGangTask {
4479 private:
4480   G1StringSymbolTableUnlinkTask _string_symbol_task;
4481   G1CodeCacheUnloadingTask      _code_cache_task;
4482   G1KlassCleaningTask           _klass_cleaning_task;
4483 
4484 public:
4485   // The constructor is run in the VMThread.
4486   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4487       AbstractGangTask("Parallel Cleaning"),
4488       _string_symbol_task(is_alive, process_strings, process_symbols),
4489       _code_cache_task(num_workers, is_alive, unloading_occurred),
4490       _klass_cleaning_task(is_alive) {
4491   }
4492 
4493   // The parallel work done by all worker threads.
4494   void work(uint worker_id) {
4495     // Do first pass of code cache cleaning.
4496     _code_cache_task.work_first_pass(worker_id);
4497 
4498     // Let the threads mark that the first pass is done.
4499     _code_cache_task.barrier_mark(worker_id);
4500 
4501     // Clean the Strings and Symbols.
4502     _string_symbol_task.work(worker_id);
4503 
4504     // Wait for all workers to finish the first code cache cleaning pass.
4505     _code_cache_task.barrier_wait(worker_id);
4506 
4507     // Do the second code cache cleaning work, which realize on
4508     // the liveness information gathered during the first pass.
4509     _code_cache_task.work_second_pass(worker_id);
4510 
4511     // Clean all klasses that were not unloaded.
4512     _klass_cleaning_task.work();
4513   }
4514 };
4515 
4516 
4517 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4518                                         bool process_strings,
4519                                         bool process_symbols,
4520                                         bool class_unloading_occurred) {
4521   uint n_workers = workers()->active_workers();
4522 
4523   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4524                                         n_workers, class_unloading_occurred);
4525   workers()->run_task(&g1_unlink_task);
4526 }
4527 
4528 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4529                                                      bool process_strings, bool process_symbols) {
4530   {
4531     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4532     workers()->run_task(&g1_unlink_task);
4533   }
4534 
4535   if (G1StringDedup::is_enabled()) {
4536     G1StringDedup::unlink(is_alive);
4537   }
4538 }
4539 
4540 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4541  private:
4542   DirtyCardQueueSet* _queue;
4543   G1CollectedHeap* _g1h;
4544  public:
4545   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4546     _queue(queue), _g1h(g1h) { }
4547 
4548   virtual void work(uint worker_id) {
4549     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4550     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4551 
4552     RedirtyLoggedCardTableEntryClosure cl(_g1h);
4553     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4554 
4555     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4556   }
4557 };
4558 
4559 void G1CollectedHeap::redirty_logged_cards() {
4560   double redirty_logged_cards_start = os::elapsedTime();
4561 
4562   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4563   dirty_card_queue_set().reset_for_par_iteration();
4564   workers()->run_task(&redirty_task);
4565 
4566   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4567   dcq.merge_bufferlists(&dirty_card_queue_set());
4568   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4569 
4570   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4571 }
4572 
4573 // Weak Reference Processing support
4574 
4575 // An always "is_alive" closure that is used to preserve referents.
4576 // If the object is non-null then it's alive.  Used in the preservation
4577 // of referent objects that are pointed to by reference objects
4578 // discovered by the CM ref processor.
4579 class G1AlwaysAliveClosure: public BoolObjectClosure {
4580   G1CollectedHeap* _g1;
4581 public:
4582   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4583   bool do_object_b(oop p) {
4584     if (p != NULL) {
4585       return true;
4586     }
4587     return false;
4588   }
4589 };
4590 
4591 bool G1STWIsAliveClosure::do_object_b(oop p) {
4592   // An object is reachable if it is outside the collection set,
4593   // or is inside and copied.
4594   return !_g1->is_in_cset(p) || p->is_forwarded();
4595 }
4596 
4597 // Non Copying Keep Alive closure
4598 class G1KeepAliveClosure: public OopClosure {
4599   G1CollectedHeap* _g1;
4600 public:
4601   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4602   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4603   void do_oop(oop* p) {
4604     oop obj = *p;
4605     assert(obj != NULL, "the caller should have filtered out NULL values");
4606 
4607     const InCSetState cset_state = _g1->in_cset_state(obj);
4608     if (!cset_state.is_in_cset_or_humongous()) {
4609       return;
4610     }
4611     if (cset_state.is_in_cset()) {
4612       assert( obj->is_forwarded(), "invariant" );
4613       *p = obj->forwardee();
4614     } else {
4615       assert(!obj->is_forwarded(), "invariant" );
4616       assert(cset_state.is_humongous(),
4617              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4618       _g1->set_humongous_is_live(obj);
4619     }
4620   }
4621 };
4622 
4623 // Copying Keep Alive closure - can be called from both
4624 // serial and parallel code as long as different worker
4625 // threads utilize different G1ParScanThreadState instances
4626 // and different queues.
4627 
4628 class G1CopyingKeepAliveClosure: public OopClosure {
4629   G1CollectedHeap*         _g1h;
4630   OopClosure*              _copy_non_heap_obj_cl;
4631   G1ParScanThreadState*    _par_scan_state;
4632 
4633 public:
4634   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4635                             OopClosure* non_heap_obj_cl,
4636                             G1ParScanThreadState* pss):
4637     _g1h(g1h),
4638     _copy_non_heap_obj_cl(non_heap_obj_cl),
4639     _par_scan_state(pss)
4640   {}
4641 
4642   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4643   virtual void do_oop(      oop* p) { do_oop_work(p); }
4644 
4645   template <class T> void do_oop_work(T* p) {
4646     oop obj = oopDesc::load_decode_heap_oop(p);
4647 
4648     if (_g1h->is_in_cset_or_humongous(obj)) {
4649       // If the referent object has been forwarded (either copied
4650       // to a new location or to itself in the event of an
4651       // evacuation failure) then we need to update the reference
4652       // field and, if both reference and referent are in the G1
4653       // heap, update the RSet for the referent.
4654       //
4655       // If the referent has not been forwarded then we have to keep
4656       // it alive by policy. Therefore we have copy the referent.
4657       //
4658       // If the reference field is in the G1 heap then we can push
4659       // on the PSS queue. When the queue is drained (after each
4660       // phase of reference processing) the object and it's followers
4661       // will be copied, the reference field set to point to the
4662       // new location, and the RSet updated. Otherwise we need to
4663       // use the the non-heap or metadata closures directly to copy
4664       // the referent object and update the pointer, while avoiding
4665       // updating the RSet.
4666 
4667       if (_g1h->is_in_g1_reserved(p)) {
4668         _par_scan_state->push_on_queue(p);
4669       } else {
4670         assert(!Metaspace::contains((const void*)p),
4671                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4672         _copy_non_heap_obj_cl->do_oop(p);
4673       }
4674     }
4675   }
4676 };
4677 
4678 // Serial drain queue closure. Called as the 'complete_gc'
4679 // closure for each discovered list in some of the
4680 // reference processing phases.
4681 
4682 class G1STWDrainQueueClosure: public VoidClosure {
4683 protected:
4684   G1CollectedHeap* _g1h;
4685   G1ParScanThreadState* _par_scan_state;
4686 
4687   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4688 
4689 public:
4690   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4691     _g1h(g1h),
4692     _par_scan_state(pss)
4693   { }
4694 
4695   void do_void() {
4696     G1ParScanThreadState* const pss = par_scan_state();
4697     pss->trim_queue();
4698   }
4699 };
4700 
4701 // Parallel Reference Processing closures
4702 
4703 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4704 // processing during G1 evacuation pauses.
4705 
4706 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4707 private:
4708   G1CollectedHeap*          _g1h;
4709   G1ParScanThreadStateSet*  _pss;
4710   RefToScanQueueSet*        _queues;
4711   WorkGang*                 _workers;
4712   uint                      _active_workers;
4713 
4714 public:
4715   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4716                            G1ParScanThreadStateSet* per_thread_states,
4717                            WorkGang* workers,
4718                            RefToScanQueueSet *task_queues,
4719                            uint n_workers) :
4720     _g1h(g1h),
4721     _pss(per_thread_states),
4722     _queues(task_queues),
4723     _workers(workers),
4724     _active_workers(n_workers)
4725   {
4726     assert(n_workers > 0, "shouldn't call this otherwise");
4727   }
4728 
4729   // Executes the given task using concurrent marking worker threads.
4730   virtual void execute(ProcessTask& task);
4731   virtual void execute(EnqueueTask& task);
4732 };
4733 
4734 // Gang task for possibly parallel reference processing
4735 
4736 class G1STWRefProcTaskProxy: public AbstractGangTask {
4737   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4738   ProcessTask&     _proc_task;
4739   G1CollectedHeap* _g1h;
4740   G1ParScanThreadStateSet* _pss;
4741   RefToScanQueueSet* _task_queues;
4742   ParallelTaskTerminator* _terminator;
4743 
4744 public:
4745   G1STWRefProcTaskProxy(ProcessTask& proc_task,
4746                         G1CollectedHeap* g1h,
4747                         G1ParScanThreadStateSet* per_thread_states,
4748                         RefToScanQueueSet *task_queues,
4749                         ParallelTaskTerminator* terminator) :
4750     AbstractGangTask("Process reference objects in parallel"),
4751     _proc_task(proc_task),
4752     _g1h(g1h),
4753     _pss(per_thread_states),
4754     _task_queues(task_queues),
4755     _terminator(terminator)
4756   {}
4757 
4758   virtual void work(uint worker_id) {
4759     // The reference processing task executed by a single worker.
4760     ResourceMark rm;
4761     HandleMark   hm;
4762 
4763     G1STWIsAliveClosure is_alive(_g1h);
4764 
4765     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4766     pss->set_ref_processor(NULL);
4767 
4768     // Keep alive closure.
4769     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4770 
4771     // Complete GC closure
4772     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4773 
4774     // Call the reference processing task's work routine.
4775     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4776 
4777     // Note we cannot assert that the refs array is empty here as not all
4778     // of the processing tasks (specifically phase2 - pp2_work) execute
4779     // the complete_gc closure (which ordinarily would drain the queue) so
4780     // the queue may not be empty.
4781   }
4782 };
4783 
4784 // Driver routine for parallel reference processing.
4785 // Creates an instance of the ref processing gang
4786 // task and has the worker threads execute it.
4787 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4788   assert(_workers != NULL, "Need parallel worker threads.");
4789 
4790   ParallelTaskTerminator terminator(_active_workers, _queues);
4791   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4792 
4793   _workers->run_task(&proc_task_proxy);
4794 }
4795 
4796 // Gang task for parallel reference enqueueing.
4797 
4798 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4799   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4800   EnqueueTask& _enq_task;
4801 
4802 public:
4803   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4804     AbstractGangTask("Enqueue reference objects in parallel"),
4805     _enq_task(enq_task)
4806   { }
4807 
4808   virtual void work(uint worker_id) {
4809     _enq_task.work(worker_id);
4810   }
4811 };
4812 
4813 // Driver routine for parallel reference enqueueing.
4814 // Creates an instance of the ref enqueueing gang
4815 // task and has the worker threads execute it.
4816 
4817 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4818   assert(_workers != NULL, "Need parallel worker threads.");
4819 
4820   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4821 
4822   _workers->run_task(&enq_task_proxy);
4823 }
4824 
4825 // End of weak reference support closures
4826 
4827 // Abstract task used to preserve (i.e. copy) any referent objects
4828 // that are in the collection set and are pointed to by reference
4829 // objects discovered by the CM ref processor.
4830 
4831 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4832 protected:
4833   G1CollectedHeap*         _g1h;
4834   G1ParScanThreadStateSet* _pss;
4835   RefToScanQueueSet*       _queues;
4836   ParallelTaskTerminator   _terminator;
4837   uint                     _n_workers;
4838 
4839 public:
4840   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4841     AbstractGangTask("ParPreserveCMReferents"),
4842     _g1h(g1h),
4843     _pss(per_thread_states),
4844     _queues(task_queues),
4845     _terminator(workers, _queues),
4846     _n_workers(workers)
4847   { }
4848 
4849   void work(uint worker_id) {
4850     ResourceMark rm;
4851     HandleMark   hm;
4852 
4853     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4854     pss->set_ref_processor(NULL);
4855     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4856 
4857     // Is alive closure
4858     G1AlwaysAliveClosure always_alive(_g1h);
4859 
4860     // Copying keep alive closure. Applied to referent objects that need
4861     // to be copied.
4862     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4863 
4864     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4865 
4866     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4867     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4868 
4869     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4870     // So this must be true - but assert just in case someone decides to
4871     // change the worker ids.
4872     assert(worker_id < limit, "sanity");
4873     assert(!rp->discovery_is_atomic(), "check this code");
4874 
4875     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4876     for (uint idx = worker_id; idx < limit; idx += stride) {
4877       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4878 
4879       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4880       while (iter.has_next()) {
4881         // Since discovery is not atomic for the CM ref processor, we
4882         // can see some null referent objects.
4883         iter.load_ptrs(DEBUG_ONLY(true));
4884         oop ref = iter.obj();
4885 
4886         // This will filter nulls.
4887         if (iter.is_referent_alive()) {
4888           iter.make_referent_alive();
4889         }
4890         iter.move_to_next();
4891       }
4892     }
4893 
4894     // Drain the queue - which may cause stealing
4895     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4896     drain_queue.do_void();
4897     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4898     assert(pss->queue_is_empty(), "should be");
4899   }
4900 };
4901 
4902 void G1CollectedHeap::process_weak_jni_handles() {
4903   double ref_proc_start = os::elapsedTime();
4904 
4905   G1STWIsAliveClosure is_alive(this);
4906   G1KeepAliveClosure keep_alive(this);
4907   JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4908 
4909   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4910   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4911 }
4912 
4913 // Weak Reference processing during an evacuation pause (part 1).
4914 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4915   double ref_proc_start = os::elapsedTime();
4916 
4917   ReferenceProcessor* rp = _ref_processor_stw;
4918   assert(rp->discovery_enabled(), "should have been enabled");
4919 
4920   // Any reference objects, in the collection set, that were 'discovered'
4921   // by the CM ref processor should have already been copied (either by
4922   // applying the external root copy closure to the discovered lists, or
4923   // by following an RSet entry).
4924   //
4925   // But some of the referents, that are in the collection set, that these
4926   // reference objects point to may not have been copied: the STW ref
4927   // processor would have seen that the reference object had already
4928   // been 'discovered' and would have skipped discovering the reference,
4929   // but would not have treated the reference object as a regular oop.
4930   // As a result the copy closure would not have been applied to the
4931   // referent object.
4932   //
4933   // We need to explicitly copy these referent objects - the references
4934   // will be processed at the end of remarking.
4935   //
4936   // We also need to do this copying before we process the reference
4937   // objects discovered by the STW ref processor in case one of these
4938   // referents points to another object which is also referenced by an
4939   // object discovered by the STW ref processor.
4940 
4941   uint no_of_gc_workers = workers()->active_workers();
4942 
4943   G1ParPreserveCMReferentsTask keep_cm_referents(this,
4944                                                  per_thread_states,
4945                                                  no_of_gc_workers,
4946                                                  _task_queues);
4947 
4948   workers()->run_task(&keep_cm_referents);
4949 
4950   // Closure to test whether a referent is alive.
4951   G1STWIsAliveClosure is_alive(this);
4952 
4953   // Even when parallel reference processing is enabled, the processing
4954   // of JNI refs is serial and performed serially by the current thread
4955   // rather than by a worker. The following PSS will be used for processing
4956   // JNI refs.
4957 
4958   // Use only a single queue for this PSS.
4959   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4960   pss->set_ref_processor(NULL);
4961   assert(pss->queue_is_empty(), "pre-condition");
4962 
4963   // Keep alive closure.
4964   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4965 
4966   // Serial Complete GC closure
4967   G1STWDrainQueueClosure drain_queue(this, pss);
4968 
4969   // Setup the soft refs policy...
4970   rp->setup_policy(false);
4971 
4972   ReferenceProcessorStats stats;
4973   if (!rp->processing_is_mt()) {
4974     // Serial reference processing...
4975     stats = rp->process_discovered_references(&is_alive,
4976                                               &keep_alive,
4977                                               &drain_queue,
4978                                               NULL,
4979                                               _gc_timer_stw);
4980   } else {
4981     // Parallel reference processing
4982     assert(rp->num_q() == no_of_gc_workers, "sanity");
4983     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
4984 
4985     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4986     stats = rp->process_discovered_references(&is_alive,
4987                                               &keep_alive,
4988                                               &drain_queue,
4989                                               &par_task_executor,
4990                                               _gc_timer_stw);
4991   }
4992 
4993   _gc_tracer_stw->report_gc_reference_stats(stats);
4994 
4995   // We have completed copying any necessary live referent objects.
4996   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4997 
4998   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4999   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5000 }
5001 
5002 // Weak Reference processing during an evacuation pause (part 2).
5003 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5004   double ref_enq_start = os::elapsedTime();
5005 
5006   ReferenceProcessor* rp = _ref_processor_stw;
5007   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5008 
5009   // Now enqueue any remaining on the discovered lists on to
5010   // the pending list.
5011   if (!rp->processing_is_mt()) {
5012     // Serial reference processing...
5013     rp->enqueue_discovered_references();
5014   } else {
5015     // Parallel reference enqueueing
5016 
5017     uint n_workers = workers()->active_workers();
5018 
5019     assert(rp->num_q() == n_workers, "sanity");
5020     assert(n_workers <= rp->max_num_q(), "sanity");
5021 
5022     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5023     rp->enqueue_discovered_references(&par_task_executor);
5024   }
5025 
5026   rp->verify_no_references_recorded();
5027   assert(!rp->discovery_enabled(), "should have been disabled");
5028 
5029   // FIXME
5030   // CM's reference processing also cleans up the string and symbol tables.
5031   // Should we do that here also? We could, but it is a serial operation
5032   // and could significantly increase the pause time.
5033 
5034   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5035   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5036 }
5037 
5038 void G1CollectedHeap::pre_evacuate_collection_set() {
5039   _expand_heap_after_alloc_failure = true;
5040   _evacuation_failed = false;
5041 
5042   // Disable the hot card cache.
5043   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5044   hot_card_cache->reset_hot_cache_claimed_index();
5045   hot_card_cache->set_use_cache(false);
5046 
5047   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5048 }
5049 
5050 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5051   // Should G1EvacuationFailureALot be in effect for this GC?
5052   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5053 
5054   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5055   double start_par_time_sec = os::elapsedTime();
5056   double end_par_time_sec;
5057 
5058   {
5059     const uint n_workers = workers()->active_workers();
5060     G1RootProcessor root_processor(this, n_workers);
5061     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5062     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5063     if (collector_state()->during_initial_mark_pause()) {
5064       ClassLoaderDataGraph::clear_claimed_marks();
5065     }
5066 
5067     print_termination_stats_hdr();
5068 
5069     workers()->run_task(&g1_par_task);
5070     end_par_time_sec = os::elapsedTime();
5071 
5072     // Closing the inner scope will execute the destructor
5073     // for the G1RootProcessor object. We record the current
5074     // elapsed time before closing the scope so that time
5075     // taken for the destructor is NOT included in the
5076     // reported parallel time.
5077   }
5078 
5079   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5080 
5081   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5082   phase_times->record_par_time(par_time_ms);
5083 
5084   double code_root_fixup_time_ms =
5085         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5086   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5087 }
5088 
5089 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5090   // Process any discovered reference objects - we have
5091   // to do this _before_ we retire the GC alloc regions
5092   // as we may have to copy some 'reachable' referent
5093   // objects (and their reachable sub-graphs) that were
5094   // not copied during the pause.
5095   if (g1_policy()->should_process_references()) {
5096     process_discovered_references(per_thread_states);
5097   } else {
5098     ref_processor_stw()->verify_no_references_recorded();
5099     process_weak_jni_handles();
5100   }
5101 
5102   if (G1StringDedup::is_enabled()) {
5103     double fixup_start = os::elapsedTime();
5104 
5105     G1STWIsAliveClosure is_alive(this);
5106     G1KeepAliveClosure keep_alive(this);
5107     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
5108 
5109     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5110     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
5111   }
5112 
5113   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5114 
5115   if (evacuation_failed()) {
5116     restore_after_evac_failure();
5117 
5118     // Reset the G1EvacuationFailureALot counters and flags
5119     // Note: the values are reset only when an actual
5120     // evacuation failure occurs.
5121     NOT_PRODUCT(reset_evacuation_should_fail();)
5122   }
5123 
5124   // Enqueue any remaining references remaining on the STW
5125   // reference processor's discovered lists. We need to do
5126   // this after the card table is cleaned (and verified) as
5127   // the act of enqueueing entries on to the pending list
5128   // will log these updates (and dirty their associated
5129   // cards). We need these updates logged to update any
5130   // RSets.
5131   if (g1_policy()->should_process_references()) {
5132     enqueue_discovered_references(per_thread_states);
5133   } else {
5134     g1_policy()->phase_times()->record_ref_enq_time(0);
5135   }
5136 
5137   _allocator->release_gc_alloc_regions(evacuation_info);
5138 
5139   per_thread_states->flush();
5140 
5141   record_obj_copy_mem_stats();
5142 
5143   _survivor_evac_stats.adjust_desired_plab_sz();
5144   _old_evac_stats.adjust_desired_plab_sz();
5145 
5146   // Reset and re-enable the hot card cache.
5147   // Note the counts for the cards in the regions in the
5148   // collection set are reset when the collection set is freed.
5149   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5150   hot_card_cache->reset_hot_cache();
5151   hot_card_cache->set_use_cache(true);
5152 
5153   purge_code_root_memory();
5154 
5155   redirty_logged_cards();
5156 #if defined(COMPILER2) || INCLUDE_JVMCI
5157   DerivedPointerTable::update_pointers();
5158 #endif
5159 }
5160 
5161 void G1CollectedHeap::record_obj_copy_mem_stats() {
5162   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
5163 
5164   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5165                                                create_g1_evac_summary(&_old_evac_stats));
5166 }
5167 
5168 void G1CollectedHeap::free_region(HeapRegion* hr,
5169                                   FreeRegionList* free_list,
5170                                   bool par,
5171                                   bool locked) {
5172   assert(!hr->is_free(), "the region should not be free");
5173   assert(!hr->is_empty(), "the region should not be empty");
5174   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5175   assert(free_list != NULL, "pre-condition");
5176 
5177   if (G1VerifyBitmaps) {
5178     MemRegion mr(hr->bottom(), hr->end());
5179     concurrent_mark()->clearRangePrevBitmap(mr);
5180   }
5181 
5182   // Clear the card counts for this region.
5183   // Note: we only need to do this if the region is not young
5184   // (since we don't refine cards in young regions).
5185   if (!hr->is_young()) {
5186     _cg1r->hot_card_cache()->reset_card_counts(hr);
5187   }
5188   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5189   free_list->add_ordered(hr);
5190 }
5191 
5192 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5193                                             FreeRegionList* free_list,
5194                                             bool par) {
5195   assert(hr->is_humongous(), "this is only for humongous regions");
5196   assert(free_list != NULL, "pre-condition");
5197   hr->clear_humongous();
5198   free_region(hr, free_list, par);
5199 }
5200 
5201 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
5202                                            const uint humongous_regions_removed) {
5203   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
5204     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5205     _old_set.bulk_remove(old_regions_removed);
5206     _humongous_set.bulk_remove(humongous_regions_removed);
5207   }
5208 
5209 }
5210 
5211 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5212   assert(list != NULL, "list can't be null");
5213   if (!list->is_empty()) {
5214     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5215     _hrm.insert_list_into_free_list(list);
5216   }
5217 }
5218 
5219 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5220   decrease_used(bytes);
5221 }
5222 
5223 class G1ParCleanupCTTask : public AbstractGangTask {
5224   G1SATBCardTableModRefBS* _ct_bs;
5225   G1CollectedHeap* _g1h;
5226   HeapRegion* volatile _su_head;
5227 public:
5228   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5229                      G1CollectedHeap* g1h) :
5230     AbstractGangTask("G1 Par Cleanup CT Task"),
5231     _ct_bs(ct_bs), _g1h(g1h) { }
5232 
5233   void work(uint worker_id) {
5234     HeapRegion* r;
5235     while (r = _g1h->pop_dirty_cards_region()) {
5236       clear_cards(r);
5237     }
5238   }
5239 
5240   void clear_cards(HeapRegion* r) {
5241     // Cards of the survivors should have already been dirtied.
5242     if (!r->is_survivor()) {
5243       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5244     }
5245   }
5246 };
5247 
5248 #ifndef PRODUCT
5249 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5250   G1CollectedHeap* _g1h;
5251   G1SATBCardTableModRefBS* _ct_bs;
5252 public:
5253   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5254     : _g1h(g1h), _ct_bs(ct_bs) { }
5255   virtual bool doHeapRegion(HeapRegion* r) {
5256     if (r->is_survivor()) {
5257       _g1h->verify_dirty_region(r);
5258     } else {
5259       _g1h->verify_not_dirty_region(r);
5260     }
5261     return false;
5262   }
5263 };
5264 
5265 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5266   // All of the region should be clean.
5267   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5268   MemRegion mr(hr->bottom(), hr->end());
5269   ct_bs->verify_not_dirty_region(mr);
5270 }
5271 
5272 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5273   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5274   // dirty allocated blocks as they allocate them. The thread that
5275   // retires each region and replaces it with a new one will do a
5276   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5277   // not dirty that area (one less thing to have to do while holding
5278   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5279   // is dirty.
5280   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5281   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5282   if (hr->is_young()) {
5283     ct_bs->verify_g1_young_region(mr);
5284   } else {
5285     ct_bs->verify_dirty_region(mr);
5286   }
5287 }
5288 
5289 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5290   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5291   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5292     verify_dirty_region(hr);
5293   }
5294 }
5295 
5296 void G1CollectedHeap::verify_dirty_young_regions() {
5297   verify_dirty_young_list(_young_list->first_region());
5298 }
5299 
5300 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5301                                                HeapWord* tams, HeapWord* end) {
5302   guarantee(tams <= end,
5303             "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5304   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5305   if (result < end) {
5306     log_info(gc, verify)("## wrong marked address on %s bitmap: " PTR_FORMAT, bitmap_name, p2i(result));
5307     log_info(gc, verify)("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, bitmap_name, p2i(tams), p2i(end));
5308     return false;
5309   }
5310   return true;
5311 }
5312 
5313 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5314   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5315   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5316 
5317   HeapWord* bottom = hr->bottom();
5318   HeapWord* ptams  = hr->prev_top_at_mark_start();
5319   HeapWord* ntams  = hr->next_top_at_mark_start();
5320   HeapWord* end    = hr->end();
5321 
5322   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5323 
5324   bool res_n = true;
5325   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5326   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5327   // if we happen to be in that state.
5328   if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5329     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5330   }
5331   if (!res_p || !res_n) {
5332     log_info(gc, verify)("#### Bitmap verification failed for " HR_FORMAT, HR_FORMAT_PARAMS(hr));
5333     log_info(gc, verify)("#### Caller: %s", caller);
5334     return false;
5335   }
5336   return true;
5337 }
5338 
5339 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5340   if (!G1VerifyBitmaps) return;
5341 
5342   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5343 }
5344 
5345 class G1VerifyBitmapClosure : public HeapRegionClosure {
5346 private:
5347   const char* _caller;
5348   G1CollectedHeap* _g1h;
5349   bool _failures;
5350 
5351 public:
5352   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5353     _caller(caller), _g1h(g1h), _failures(false) { }
5354 
5355   bool failures() { return _failures; }
5356 
5357   virtual bool doHeapRegion(HeapRegion* hr) {
5358     bool result = _g1h->verify_bitmaps(_caller, hr);
5359     if (!result) {
5360       _failures = true;
5361     }
5362     return false;
5363   }
5364 };
5365 
5366 void G1CollectedHeap::check_bitmaps(const char* caller) {
5367   if (!G1VerifyBitmaps) return;
5368 
5369   G1VerifyBitmapClosure cl(caller, this);
5370   heap_region_iterate(&cl);
5371   guarantee(!cl.failures(), "bitmap verification");
5372 }
5373 
5374 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5375  private:
5376   bool _failures;
5377  public:
5378   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5379 
5380   virtual bool doHeapRegion(HeapRegion* hr) {
5381     uint i = hr->hrm_index();
5382     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5383     if (hr->is_humongous()) {
5384       if (hr->in_collection_set()) {
5385         log_info(gc, verify)("## humongous region %u in CSet", i);
5386         _failures = true;
5387         return true;
5388       }
5389       if (cset_state.is_in_cset()) {
5390         log_info(gc, verify)("## inconsistent cset state " CSETSTATE_FORMAT " for humongous region %u", cset_state.value(), i);
5391         _failures = true;
5392         return true;
5393       }
5394       if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5395         log_info(gc, verify)("## inconsistent cset state " CSETSTATE_FORMAT " for continues humongous region %u", cset_state.value(), i);
5396         _failures = true;
5397         return true;
5398       }
5399     } else {
5400       if (cset_state.is_humongous()) {
5401         log_info(gc, verify)("## inconsistent cset state " CSETSTATE_FORMAT " for non-humongous region %u", cset_state.value(), i);
5402         _failures = true;
5403         return true;
5404       }
5405       if (hr->in_collection_set() != cset_state.is_in_cset()) {
5406         log_info(gc, verify)("## in CSet %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
5407                              hr->in_collection_set(), cset_state.value(), i);
5408         _failures = true;
5409         return true;
5410       }
5411       if (cset_state.is_in_cset()) {
5412         if (hr->is_young() != (cset_state.is_young())) {
5413           log_info(gc, verify)("## is_young %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
5414                                hr->is_young(), cset_state.value(), i);
5415           _failures = true;
5416           return true;
5417         }
5418         if (hr->is_old() != (cset_state.is_old())) {
5419           log_info(gc, verify)("## is_old %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
5420                                hr->is_old(), cset_state.value(), i);
5421           _failures = true;
5422           return true;
5423         }
5424       }
5425     }
5426     return false;
5427   }
5428 
5429   bool failures() const { return _failures; }
5430 };
5431 
5432 bool G1CollectedHeap::check_cset_fast_test() {
5433   G1CheckCSetFastTableClosure cl;
5434   _hrm.iterate(&cl);
5435   return !cl.failures();
5436 }
5437 #endif // PRODUCT
5438 
5439 class G1ParScrubRemSetTask: public AbstractGangTask {
5440 protected:
5441   G1RemSet* _g1rs;
5442   BitMap* _region_bm;
5443   BitMap* _card_bm;
5444   HeapRegionClaimer _hrclaimer;
5445 
5446 public:
5447   G1ParScrubRemSetTask(G1RemSet* g1_rs, BitMap* region_bm, BitMap* card_bm, uint num_workers) :
5448     AbstractGangTask("G1 ScrubRS"),
5449     _g1rs(g1_rs),
5450     _region_bm(region_bm),
5451     _card_bm(card_bm),
5452     _hrclaimer(num_workers) {
5453   }
5454 
5455   void work(uint worker_id) {
5456     _g1rs->scrub(_region_bm, _card_bm, worker_id, &_hrclaimer);
5457   }
5458 };
5459 
5460 void G1CollectedHeap::scrub_rem_set(BitMap* region_bm, BitMap* card_bm) {
5461   uint num_workers = workers()->active_workers();
5462   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), region_bm, card_bm, num_workers);
5463   workers()->run_task(&g1_par_scrub_rs_task);
5464 }
5465 
5466 void G1CollectedHeap::cleanUpCardTable() {
5467   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5468   double start = os::elapsedTime();
5469 
5470   {
5471     // Iterate over the dirty cards region list.
5472     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5473 
5474     workers()->run_task(&cleanup_task);
5475 #ifndef PRODUCT
5476     if (G1VerifyCTCleanup || VerifyAfterGC) {
5477       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5478       heap_region_iterate(&cleanup_verifier);
5479     }
5480 #endif
5481   }
5482 
5483   double elapsed = os::elapsedTime() - start;
5484   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5485 }
5486 
5487 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5488   size_t pre_used = 0;
5489   FreeRegionList local_free_list("Local List for CSet Freeing");
5490 
5491   double young_time_ms     = 0.0;
5492   double non_young_time_ms = 0.0;
5493 
5494   // Since the collection set is a superset of the the young list,
5495   // all we need to do to clear the young list is clear its
5496   // head and length, and unlink any young regions in the code below
5497   _young_list->clear();
5498 
5499   G1CollectorPolicy* policy = g1_policy();
5500 
5501   double start_sec = os::elapsedTime();
5502   bool non_young = true;
5503 
5504   HeapRegion* cur = cs_head;
5505   int age_bound = -1;
5506   size_t rs_lengths = 0;
5507 
5508   while (cur != NULL) {
5509     assert(!is_on_master_free_list(cur), "sanity");
5510     if (non_young) {
5511       if (cur->is_young()) {
5512         double end_sec = os::elapsedTime();
5513         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5514         non_young_time_ms += elapsed_ms;
5515 
5516         start_sec = os::elapsedTime();
5517         non_young = false;
5518       }
5519     } else {
5520       if (!cur->is_young()) {
5521         double end_sec = os::elapsedTime();
5522         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5523         young_time_ms += elapsed_ms;
5524 
5525         start_sec = os::elapsedTime();
5526         non_young = true;
5527       }
5528     }
5529 
5530     rs_lengths += cur->rem_set()->occupied_locked();
5531 
5532     HeapRegion* next = cur->next_in_collection_set();
5533     assert(cur->in_collection_set(), "bad CS");
5534     cur->set_next_in_collection_set(NULL);
5535     clear_in_cset(cur);
5536 
5537     if (cur->is_young()) {
5538       int index = cur->young_index_in_cset();
5539       assert(index != -1, "invariant");
5540       assert((uint) index < policy->young_cset_region_length(), "invariant");
5541       size_t words_survived = surviving_young_words[index];
5542       cur->record_surv_words_in_group(words_survived);
5543 
5544       // At this point the we have 'popped' cur from the collection set
5545       // (linked via next_in_collection_set()) but it is still in the
5546       // young list (linked via next_young_region()). Clear the
5547       // _next_young_region field.
5548       cur->set_next_young_region(NULL);
5549     } else {
5550       int index = cur->young_index_in_cset();
5551       assert(index == -1, "invariant");
5552     }
5553 
5554     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5555             (!cur->is_young() && cur->young_index_in_cset() == -1),
5556             "invariant" );
5557 
5558     if (!cur->evacuation_failed()) {
5559       MemRegion used_mr = cur->used_region();
5560 
5561       // And the region is empty.
5562       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5563       pre_used += cur->used();
5564       free_region(cur, &local_free_list, false /* par */, true /* locked */);
5565     } else {
5566       cur->uninstall_surv_rate_group();
5567       if (cur->is_young()) {
5568         cur->set_young_index_in_cset(-1);
5569       }
5570       cur->set_evacuation_failed(false);
5571       // When moving a young gen region to old gen, we "allocate" that whole region
5572       // there. This is in addition to any already evacuated objects. Notify the
5573       // policy about that.
5574       // Old gen regions do not cause an additional allocation: both the objects
5575       // still in the region and the ones already moved are accounted for elsewhere.
5576       if (cur->is_young()) {
5577         policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
5578       }
5579       // The region is now considered to be old.
5580       cur->set_old();
5581       // Do some allocation statistics accounting. Regions that failed evacuation
5582       // are always made old, so there is no need to update anything in the young
5583       // gen statistics, but we need to update old gen statistics.
5584       size_t used_words = cur->marked_bytes() / HeapWordSize;
5585       _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5586       _old_set.add(cur);
5587       evacuation_info.increment_collectionset_used_after(cur->used());
5588     }
5589     cur = next;
5590   }
5591 
5592   evacuation_info.set_regions_freed(local_free_list.length());
5593   policy->record_max_rs_lengths(rs_lengths);
5594   policy->cset_regions_freed();
5595 
5596   double end_sec = os::elapsedTime();
5597   double elapsed_ms = (end_sec - start_sec) * 1000.0;
5598 
5599   if (non_young) {
5600     non_young_time_ms += elapsed_ms;
5601   } else {
5602     young_time_ms += elapsed_ms;
5603   }
5604 
5605   prepend_to_freelist(&local_free_list);
5606   decrement_summary_bytes(pre_used);
5607   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5608   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5609 }
5610 
5611 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5612  private:
5613   FreeRegionList* _free_region_list;
5614   HeapRegionSet* _proxy_set;
5615   uint _humongous_regions_removed;
5616   size_t _freed_bytes;
5617  public:
5618 
5619   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5620     _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
5621   }
5622 
5623   virtual bool doHeapRegion(HeapRegion* r) {
5624     if (!r->is_starts_humongous()) {
5625       return false;
5626     }
5627 
5628     G1CollectedHeap* g1h = G1CollectedHeap::heap();
5629 
5630     oop obj = (oop)r->bottom();
5631     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5632 
5633     // The following checks whether the humongous object is live are sufficient.
5634     // The main additional check (in addition to having a reference from the roots
5635     // or the young gen) is whether the humongous object has a remembered set entry.
5636     //
5637     // A humongous object cannot be live if there is no remembered set for it
5638     // because:
5639     // - there can be no references from within humongous starts regions referencing
5640     // the object because we never allocate other objects into them.
5641     // (I.e. there are no intra-region references that may be missed by the
5642     // remembered set)
5643     // - as soon there is a remembered set entry to the humongous starts region
5644     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5645     // until the end of a concurrent mark.
5646     //
5647     // It is not required to check whether the object has been found dead by marking
5648     // or not, in fact it would prevent reclamation within a concurrent cycle, as
5649     // all objects allocated during that time are considered live.
5650     // SATB marking is even more conservative than the remembered set.
5651     // So if at this point in the collection there is no remembered set entry,
5652     // nobody has a reference to it.
5653     // At the start of collection we flush all refinement logs, and remembered sets
5654     // are completely up-to-date wrt to references to the humongous object.
5655     //
5656     // Other implementation considerations:
5657     // - never consider object arrays at this time because they would pose
5658     // considerable effort for cleaning up the the remembered sets. This is
5659     // required because stale remembered sets might reference locations that
5660     // are currently allocated into.
5661     uint region_idx = r->hrm_index();
5662     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5663         !r->rem_set()->is_empty()) {
5664       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",
5665                                region_idx,
5666                                (size_t)obj->size() * HeapWordSize,
5667                                p2i(r->bottom()),
5668                                r->rem_set()->occupied(),
5669                                r->rem_set()->strong_code_roots_list_length(),
5670                                next_bitmap->isMarked(r->bottom()),
5671                                g1h->is_humongous_reclaim_candidate(region_idx),
5672                                obj->is_typeArray()
5673                               );
5674       return false;
5675     }
5676 
5677     guarantee(obj->is_typeArray(),
5678               "Only eagerly reclaiming type arrays is supported, but the object "
5679               PTR_FORMAT " is not.", p2i(r->bottom()));
5680 
5681     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",
5682                              region_idx,
5683                              (size_t)obj->size() * HeapWordSize,
5684                              p2i(r->bottom()),
5685                              r->rem_set()->occupied(),
5686                              r->rem_set()->strong_code_roots_list_length(),
5687                              next_bitmap->isMarked(r->bottom()),
5688                              g1h->is_humongous_reclaim_candidate(region_idx),
5689                              obj->is_typeArray()
5690                             );
5691 
5692     // Need to clear mark bit of the humongous object if already set.
5693     if (next_bitmap->isMarked(r->bottom())) {
5694       next_bitmap->clear(r->bottom());
5695     }
5696     do {
5697       HeapRegion* next = g1h->next_region_in_humongous(r);
5698       _freed_bytes += r->used();
5699       r->set_containing_set(NULL);
5700       _humongous_regions_removed++;
5701       g1h->free_humongous_region(r, _free_region_list, false);
5702       r = next;
5703     } while (r != NULL);
5704 
5705     return false;
5706   }
5707 
5708   uint humongous_free_count() {
5709     return _humongous_regions_removed;
5710   }
5711 
5712   size_t bytes_freed() const {
5713     return _freed_bytes;
5714   }
5715 };
5716 
5717 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5718   assert_at_safepoint(true);
5719 
5720   if (!G1EagerReclaimHumongousObjects ||
5721       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5722     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5723     return;
5724   }
5725 
5726   double start_time = os::elapsedTime();
5727 
5728   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5729 
5730   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5731   heap_region_iterate(&cl);
5732 
5733   remove_from_old_sets(0, cl.humongous_free_count());
5734 
5735   G1HRPrinter* hrp = hr_printer();
5736   if (hrp->is_active()) {
5737     FreeRegionListIterator iter(&local_cleanup_list);
5738     while (iter.more_available()) {
5739       HeapRegion* hr = iter.get_next();
5740       hrp->cleanup(hr);
5741     }
5742   }
5743 
5744   prepend_to_freelist(&local_cleanup_list);
5745   decrement_summary_bytes(cl.bytes_freed());
5746 
5747   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5748                                                                     cl.humongous_free_count());
5749 }
5750 
5751 // This routine is similar to the above but does not record
5752 // any policy statistics or update free lists; we are abandoning
5753 // the current incremental collection set in preparation of a
5754 // full collection. After the full GC we will start to build up
5755 // the incremental collection set again.
5756 // This is only called when we're doing a full collection
5757 // and is immediately followed by the tearing down of the young list.
5758 
5759 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5760   HeapRegion* cur = cs_head;
5761 
5762   while (cur != NULL) {
5763     HeapRegion* next = cur->next_in_collection_set();
5764     assert(cur->in_collection_set(), "bad CS");
5765     cur->set_next_in_collection_set(NULL);
5766     clear_in_cset(cur);
5767     cur->set_young_index_in_cset(-1);
5768     cur = next;
5769   }
5770 }
5771 
5772 void G1CollectedHeap::set_free_regions_coming() {
5773   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5774 
5775   assert(!free_regions_coming(), "pre-condition");
5776   _free_regions_coming = true;
5777 }
5778 
5779 void G1CollectedHeap::reset_free_regions_coming() {
5780   assert(free_regions_coming(), "pre-condition");
5781 
5782   {
5783     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5784     _free_regions_coming = false;
5785     SecondaryFreeList_lock->notify_all();
5786   }
5787 
5788   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5789 }
5790 
5791 void G1CollectedHeap::wait_while_free_regions_coming() {
5792   // Most of the time we won't have to wait, so let's do a quick test
5793   // first before we take the lock.
5794   if (!free_regions_coming()) {
5795     return;
5796   }
5797 
5798   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5799 
5800   {
5801     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5802     while (free_regions_coming()) {
5803       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5804     }
5805   }
5806 
5807   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5808 }
5809 
5810 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5811   return _allocator->is_retained_old_region(hr);
5812 }
5813 
5814 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5815   _young_list->push_region(hr);
5816 }
5817 
5818 class NoYoungRegionsClosure: public HeapRegionClosure {
5819 private:
5820   bool _success;
5821 public:
5822   NoYoungRegionsClosure() : _success(true) { }
5823   bool doHeapRegion(HeapRegion* r) {
5824     if (r->is_young()) {
5825       log_info(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5826                            p2i(r->bottom()), p2i(r->end()));
5827       _success = false;
5828     }
5829     return false;
5830   }
5831   bool success() { return _success; }
5832 };
5833 
5834 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5835   bool ret = _young_list->check_list_empty(check_sample);
5836 
5837   if (check_heap) {
5838     NoYoungRegionsClosure closure;
5839     heap_region_iterate(&closure);
5840     ret = ret && closure.success();
5841   }
5842 
5843   return ret;
5844 }
5845 
5846 class TearDownRegionSetsClosure : public HeapRegionClosure {
5847 private:
5848   HeapRegionSet *_old_set;
5849 
5850 public:
5851   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5852 
5853   bool doHeapRegion(HeapRegion* r) {
5854     if (r->is_old()) {
5855       _old_set->remove(r);
5856     } else {
5857       // We ignore free regions, we'll empty the free list afterwards.
5858       // We ignore young regions, we'll empty the young list afterwards.
5859       // We ignore humongous regions, we're not tearing down the
5860       // humongous regions set.
5861       assert(r->is_free() || r->is_young() || r->is_humongous(),
5862              "it cannot be another type");
5863     }
5864     return false;
5865   }
5866 
5867   ~TearDownRegionSetsClosure() {
5868     assert(_old_set->is_empty(), "post-condition");
5869   }
5870 };
5871 
5872 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5873   assert_at_safepoint(true /* should_be_vm_thread */);
5874 
5875   if (!free_list_only) {
5876     TearDownRegionSetsClosure cl(&_old_set);
5877     heap_region_iterate(&cl);
5878 
5879     // Note that emptying the _young_list is postponed and instead done as
5880     // the first step when rebuilding the regions sets again. The reason for
5881     // this is that during a full GC string deduplication needs to know if
5882     // a collected region was young or old when the full GC was initiated.
5883   }
5884   _hrm.remove_all_free_regions();
5885 }
5886 
5887 void G1CollectedHeap::increase_used(size_t bytes) {
5888   _summary_bytes_used += bytes;
5889 }
5890 
5891 void G1CollectedHeap::decrease_used(size_t bytes) {
5892   assert(_summary_bytes_used >= bytes,
5893          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5894          _summary_bytes_used, bytes);
5895   _summary_bytes_used -= bytes;
5896 }
5897 
5898 void G1CollectedHeap::set_used(size_t bytes) {
5899   _summary_bytes_used = bytes;
5900 }
5901 
5902 class RebuildRegionSetsClosure : public HeapRegionClosure {
5903 private:
5904   bool            _free_list_only;
5905   HeapRegionSet*   _old_set;
5906   HeapRegionManager*   _hrm;
5907   size_t          _total_used;
5908 
5909 public:
5910   RebuildRegionSetsClosure(bool free_list_only,
5911                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5912     _free_list_only(free_list_only),
5913     _old_set(old_set), _hrm(hrm), _total_used(0) {
5914     assert(_hrm->num_free_regions() == 0, "pre-condition");
5915     if (!free_list_only) {
5916       assert(_old_set->is_empty(), "pre-condition");
5917     }
5918   }
5919 
5920   bool doHeapRegion(HeapRegion* r) {
5921     if (r->is_empty()) {
5922       // Add free regions to the free list
5923       r->set_free();
5924       r->set_allocation_context(AllocationContext::system());
5925       _hrm->insert_into_free_list(r);
5926     } else if (!_free_list_only) {
5927       assert(!r->is_young(), "we should not come across young regions");
5928 
5929       if (r->is_humongous()) {
5930         // We ignore humongous regions. We left the humongous set unchanged.
5931       } else {
5932         // Objects that were compacted would have ended up on regions
5933         // that were previously old or free.  Archive regions (which are
5934         // old) will not have been touched.
5935         assert(r->is_free() || r->is_old(), "invariant");
5936         // We now consider them old, so register as such. Leave
5937         // archive regions set that way, however, while still adding
5938         // them to the old set.
5939         if (!r->is_archive()) {
5940           r->set_old();
5941         }
5942         _old_set->add(r);
5943       }
5944       _total_used += r->used();
5945     }
5946 
5947     return false;
5948   }
5949 
5950   size_t total_used() {
5951     return _total_used;
5952   }
5953 };
5954 
5955 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5956   assert_at_safepoint(true /* should_be_vm_thread */);
5957 
5958   if (!free_list_only) {
5959     _young_list->empty_list();
5960   }
5961 
5962   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5963   heap_region_iterate(&cl);
5964 
5965   if (!free_list_only) {
5966     set_used(cl.total_used());
5967     if (_archive_allocator != NULL) {
5968       _archive_allocator->clear_used();
5969     }
5970   }
5971   assert(used_unlocked() == recalculate_used(),
5972          "inconsistent used_unlocked(), "
5973          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5974          used_unlocked(), recalculate_used());
5975 }
5976 
5977 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5978   _refine_cte_cl->set_concurrent(concurrent);
5979 }
5980 
5981 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5982   HeapRegion* hr = heap_region_containing(p);
5983   return hr->is_in(p);
5984 }
5985 
5986 // Methods for the mutator alloc region
5987 
5988 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5989                                                       bool force) {
5990   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5991   assert(!force || g1_policy()->can_expand_young_list(),
5992          "if force is true we should be able to expand the young list");
5993   bool young_list_full = g1_policy()->is_young_list_full();
5994   if (force || !young_list_full) {
5995     HeapRegion* new_alloc_region = new_region(word_size,
5996                                               false /* is_old */,
5997                                               false /* do_expand */);
5998     if (new_alloc_region != NULL) {
5999       set_region_short_lived_locked(new_alloc_region);
6000       _hr_printer.alloc(new_alloc_region, young_list_full);
6001       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6002       return new_alloc_region;
6003     }
6004   }
6005   return NULL;
6006 }
6007 
6008 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6009                                                   size_t allocated_bytes) {
6010   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6011   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6012 
6013   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6014   increase_used(allocated_bytes);
6015   _hr_printer.retire(alloc_region);
6016   // We update the eden sizes here, when the region is retired,
6017   // instead of when it's allocated, since this is the point that its
6018   // used space has been recored in _summary_bytes_used.
6019   g1mm()->update_eden_size();
6020 }
6021 
6022 // Methods for the GC alloc regions
6023 
6024 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6025                                                  uint count,
6026                                                  InCSetState dest) {
6027   assert(FreeList_lock->owned_by_self(), "pre-condition");
6028 
6029   if (count < g1_policy()->max_regions(dest)) {
6030     const bool is_survivor = (dest.is_young());
6031     HeapRegion* new_alloc_region = new_region(word_size,
6032                                               !is_survivor,
6033                                               true /* do_expand */);
6034     if (new_alloc_region != NULL) {
6035       // We really only need to do this for old regions given that we
6036       // should never scan survivors. But it doesn't hurt to do it
6037       // for survivors too.
6038       new_alloc_region->record_timestamp();
6039       if (is_survivor) {
6040         new_alloc_region->set_survivor();
6041         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6042       } else {
6043         new_alloc_region->set_old();
6044         check_bitmaps("Old Region Allocation", new_alloc_region);
6045       }
6046       _hr_printer.alloc(new_alloc_region);
6047       bool during_im = collector_state()->during_initial_mark_pause();
6048       new_alloc_region->note_start_of_copying(during_im);
6049       return new_alloc_region;
6050     }
6051   }
6052   return NULL;
6053 }
6054 
6055 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6056                                              size_t allocated_bytes,
6057                                              InCSetState dest) {
6058   bool during_im = collector_state()->during_initial_mark_pause();
6059   alloc_region->note_end_of_copying(during_im);
6060   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6061   if (dest.is_young()) {
6062     young_list()->add_survivor_region(alloc_region);
6063   } else {
6064     _old_set.add(alloc_region);
6065   }
6066   _hr_printer.retire(alloc_region);
6067 }
6068 
6069 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6070   bool expanded = false;
6071   uint index = _hrm.find_highest_free(&expanded);
6072 
6073   if (index != G1_NO_HRM_INDEX) {
6074     if (expanded) {
6075       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
6076                                 HeapRegion::GrainWords * HeapWordSize);
6077     }
6078     _hrm.allocate_free_regions_starting_at(index, 1);
6079     return region_at(index);
6080   }
6081   return NULL;
6082 }
6083 
6084 // Heap region set verification
6085 
6086 class VerifyRegionListsClosure : public HeapRegionClosure {
6087 private:
6088   HeapRegionSet*   _old_set;
6089   HeapRegionSet*   _humongous_set;
6090   HeapRegionManager*   _hrm;
6091 
6092 public:
6093   uint _old_count;
6094   uint _humongous_count;
6095   uint _free_count;
6096 
6097   VerifyRegionListsClosure(HeapRegionSet* old_set,
6098                            HeapRegionSet* humongous_set,
6099                            HeapRegionManager* hrm) :
6100     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6101     _old_count(), _humongous_count(), _free_count(){ }
6102 
6103   bool doHeapRegion(HeapRegion* hr) {
6104     if (hr->is_young()) {
6105       // TODO
6106     } else if (hr->is_humongous()) {
6107       assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6108       _humongous_count++;
6109     } else if (hr->is_empty()) {
6110       assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6111       _free_count++;
6112     } else if (hr->is_old()) {
6113       assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6114       _old_count++;
6115     } else {
6116       // There are no other valid region types. Check for one invalid
6117       // one we can identify: pinned without old or humongous set.
6118       assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6119       ShouldNotReachHere();
6120     }
6121     return false;
6122   }
6123 
6124   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6125     guarantee(old_set->length() == _old_count, "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count);
6126     guarantee(humongous_set->length() == _humongous_count, "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count);
6127     guarantee(free_list->num_free_regions() == _free_count, "Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count);
6128   }
6129 };
6130 
6131 void G1CollectedHeap::verify_region_sets() {
6132   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6133 
6134   // First, check the explicit lists.
6135   _hrm.verify();
6136   {
6137     // Given that a concurrent operation might be adding regions to
6138     // the secondary free list we have to take the lock before
6139     // verifying it.
6140     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6141     _secondary_free_list.verify_list();
6142   }
6143 
6144   // If a concurrent region freeing operation is in progress it will
6145   // be difficult to correctly attributed any free regions we come
6146   // across to the correct free list given that they might belong to
6147   // one of several (free_list, secondary_free_list, any local lists,
6148   // etc.). So, if that's the case we will skip the rest of the
6149   // verification operation. Alternatively, waiting for the concurrent
6150   // operation to complete will have a non-trivial effect on the GC's
6151   // operation (no concurrent operation will last longer than the
6152   // interval between two calls to verification) and it might hide
6153   // any issues that we would like to catch during testing.
6154   if (free_regions_coming()) {
6155     return;
6156   }
6157 
6158   // Make sure we append the secondary_free_list on the free_list so
6159   // that all free regions we will come across can be safely
6160   // attributed to the free_list.
6161   append_secondary_free_list_if_not_empty_with_lock();
6162 
6163   // Finally, make sure that the region accounting in the lists is
6164   // consistent with what we see in the heap.
6165 
6166   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6167   heap_region_iterate(&cl);
6168   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6169 }
6170 
6171 // Optimized nmethod scanning
6172 
6173 class RegisterNMethodOopClosure: public OopClosure {
6174   G1CollectedHeap* _g1h;
6175   nmethod* _nm;
6176 
6177   template <class T> void do_oop_work(T* p) {
6178     T heap_oop = oopDesc::load_heap_oop(p);
6179     if (!oopDesc::is_null(heap_oop)) {
6180       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6181       HeapRegion* hr = _g1h->heap_region_containing(obj);
6182       assert(!hr->is_continues_humongous(),
6183              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6184              " starting at " HR_FORMAT,
6185              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6186 
6187       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6188       hr->add_strong_code_root_locked(_nm);
6189     }
6190   }
6191 
6192 public:
6193   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6194     _g1h(g1h), _nm(nm) {}
6195 
6196   void do_oop(oop* p)       { do_oop_work(p); }
6197   void do_oop(narrowOop* p) { do_oop_work(p); }
6198 };
6199 
6200 class UnregisterNMethodOopClosure: public OopClosure {
6201   G1CollectedHeap* _g1h;
6202   nmethod* _nm;
6203 
6204   template <class T> void do_oop_work(T* p) {
6205     T heap_oop = oopDesc::load_heap_oop(p);
6206     if (!oopDesc::is_null(heap_oop)) {
6207       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6208       HeapRegion* hr = _g1h->heap_region_containing(obj);
6209       assert(!hr->is_continues_humongous(),
6210              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6211              " starting at " HR_FORMAT,
6212              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6213 
6214       hr->remove_strong_code_root(_nm);
6215     }
6216   }
6217 
6218 public:
6219   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6220     _g1h(g1h), _nm(nm) {}
6221 
6222   void do_oop(oop* p)       { do_oop_work(p); }
6223   void do_oop(narrowOop* p) { do_oop_work(p); }
6224 };
6225 
6226 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6227   CollectedHeap::register_nmethod(nm);
6228 
6229   guarantee(nm != NULL, "sanity");
6230   RegisterNMethodOopClosure reg_cl(this, nm);
6231   nm->oops_do(&reg_cl);
6232 }
6233 
6234 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6235   CollectedHeap::unregister_nmethod(nm);
6236 
6237   guarantee(nm != NULL, "sanity");
6238   UnregisterNMethodOopClosure reg_cl(this, nm);
6239   nm->oops_do(&reg_cl, true);
6240 }
6241 
6242 void G1CollectedHeap::purge_code_root_memory() {
6243   double purge_start = os::elapsedTime();
6244   G1CodeRootSet::purge();
6245   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6246   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6247 }
6248 
6249 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6250   G1CollectedHeap* _g1h;
6251 
6252 public:
6253   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6254     _g1h(g1h) {}
6255 
6256   void do_code_blob(CodeBlob* cb) {
6257     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6258     if (nm == NULL) {
6259       return;
6260     }
6261 
6262     if (ScavengeRootsInCode) {
6263       _g1h->register_nmethod(nm);
6264     }
6265   }
6266 };
6267 
6268 void G1CollectedHeap::rebuild_strong_code_roots() {
6269   RebuildStrongCodeRootClosure blob_cl(this);
6270   CodeCache::blobs_do(&blob_cl);
6271 }