1 /*
   2  * Copyright (c) 2001, 2016, 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/g1CollectionSet.hpp"
  38 #include "gc/g1/g1CollectorPolicy.hpp"
  39 #include "gc/g1/g1CollectorState.hpp"
  40 #include "gc/g1/g1EvacStats.inline.hpp"
  41 #include "gc/g1/g1GCPhaseTimes.hpp"
  42 #include "gc/g1/g1HeapSizingPolicy.hpp"
  43 #include "gc/g1/g1HeapTransition.hpp"
  44 #include "gc/g1/g1HeapVerifier.hpp"
  45 #include "gc/g1/g1MarkSweep.hpp"
  46 #include "gc/g1/g1OopClosures.inline.hpp"
  47 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  48 #include "gc/g1/g1Policy.hpp"
  49 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  50 #include "gc/g1/g1RemSet.inline.hpp"
  51 #include "gc/g1/g1RootClosures.hpp"
  52 #include "gc/g1/g1RootProcessor.hpp"
  53 #include "gc/g1/g1StringDedup.hpp"
  54 #include "gc/g1/g1YCTypes.hpp"
  55 #include "gc/g1/heapRegion.inline.hpp"
  56 #include "gc/g1/heapRegionRemSet.hpp"
  57 #include "gc/g1/heapRegionSet.inline.hpp"
  58 #include "gc/g1/suspendibleThreadSet.hpp"
  59 #include "gc/g1/vm_operations_g1.hpp"
  60 #include "gc/shared/gcHeapSummary.hpp"
  61 #include "gc/shared/gcId.hpp"
  62 #include "gc/shared/gcLocker.inline.hpp"
  63 #include "gc/shared/gcTimer.hpp"
  64 #include "gc/shared/gcTrace.hpp"
  65 #include "gc/shared/gcTraceTime.inline.hpp"
  66 #include "gc/shared/generationSpec.hpp"
  67 #include "gc/shared/isGCActiveMark.hpp"
  68 #include "gc/shared/referenceProcessor.inline.hpp"
  69 #include "gc/shared/taskqueue.inline.hpp"
  70 #include "logging/log.hpp"
  71 #include "memory/allocation.hpp"
  72 #include "memory/iterator.hpp"
  73 #include "memory/resourceArea.hpp"
  74 #include "oops/oop.inline.hpp"
  75 #include "runtime/atomic.inline.hpp"
  76 #include "runtime/init.hpp"
  77 #include "runtime/orderAccess.inline.hpp"
  78 #include "runtime/vmThread.hpp"
  79 #include "utilities/globalDefinitions.hpp"
  80 #include "utilities/stack.inline.hpp"
  81 
  82 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  83 
  84 // INVARIANTS/NOTES
  85 //
  86 // All allocation activity covered by the G1CollectedHeap interface is
  87 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  88 // and allocate_new_tlab, which are the "entry" points to the
  89 // allocation code from the rest of the JVM.  (Note that this does not
  90 // apply to TLAB allocation, which is not part of this interface: it
  91 // is done by clients of this interface.)
  92 
  93 // Local to this file.
  94 
  95 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  96   bool _concurrent;
  97 public:
  98   RefineCardTableEntryClosure() : _concurrent(true) { }
  99 
 100   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 101     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, NULL);
 102     // This path is executed by the concurrent refine or mutator threads,
 103     // concurrently, and so we do not care if card_ptr contains references
 104     // that point into the collection set.
 105     assert(!oops_into_cset, "should be");
 106 
 107     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 108       // Caller will actually yield.
 109       return false;
 110     }
 111     // Otherwise, we finished successfully; return true.
 112     return true;
 113   }
 114 
 115   void set_concurrent(bool b) { _concurrent = b; }
 116 };
 117 
 118 
 119 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 120  private:
 121   size_t _num_dirtied;
 122   G1CollectedHeap* _g1h;
 123   G1SATBCardTableLoggingModRefBS* _g1_bs;
 124 
 125   HeapRegion* region_for_card(jbyte* card_ptr) const {
 126     return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
 127   }
 128 
 129   bool will_become_free(HeapRegion* hr) const {
 130     // A region will be freed by free_collection_set if the region is in the
 131     // collection set and has not had an evacuation failure.
 132     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 133   }
 134 
 135  public:
 136   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 137     _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
 138 
 139   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 140     HeapRegion* hr = region_for_card(card_ptr);
 141 
 142     // Should only dirty cards in regions that won't be freed.
 143     if (!will_become_free(hr)) {
 144       *card_ptr = CardTableModRefBS::dirty_card_val();
 145       _num_dirtied++;
 146     }
 147 
 148     return true;
 149   }
 150 
 151   size_t num_dirtied()   const { return _num_dirtied; }
 152 };
 153 
 154 
 155 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 156   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 157 }
 158 
 159 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 160   // The from card cache is not the memory that is actually committed. So we cannot
 161   // take advantage of the zero_filled parameter.
 162   reset_from_card_cache(start_idx, num_regions);
 163 }
 164 
 165 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 166 {
 167   // Claim the right to put the region on the dirty cards region list
 168   // by installing a self pointer.
 169   HeapRegion* next = hr->get_next_dirty_cards_region();
 170   if (next == NULL) {
 171     HeapRegion* res = (HeapRegion*)
 172       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 173                           NULL);
 174     if (res == NULL) {
 175       HeapRegion* head;
 176       do {
 177         // Put the region to the dirty cards region list.
 178         head = _dirty_cards_region_list;
 179         next = (HeapRegion*)
 180           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 181         if (next == head) {
 182           assert(hr->get_next_dirty_cards_region() == hr,
 183                  "hr->get_next_dirty_cards_region() != hr");
 184           if (next == NULL) {
 185             // The last region in the list points to itself.
 186             hr->set_next_dirty_cards_region(hr);
 187           } else {
 188             hr->set_next_dirty_cards_region(next);
 189           }
 190         }
 191       } while (next != head);
 192     }
 193   }
 194 }
 195 
 196 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 197 {
 198   HeapRegion* head;
 199   HeapRegion* hr;
 200   do {
 201     head = _dirty_cards_region_list;
 202     if (head == NULL) {
 203       return NULL;
 204     }
 205     HeapRegion* new_head = head->get_next_dirty_cards_region();
 206     if (head == new_head) {
 207       // The last region.
 208       new_head = NULL;
 209     }
 210     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 211                                           head);
 212   } while (hr != head);
 213   assert(hr != NULL, "invariant");
 214   hr->set_next_dirty_cards_region(NULL);
 215   return hr;
 216 }
 217 
 218 // Returns true if the reference points to an object that
 219 // can move in an incremental collection.
 220 bool G1CollectedHeap::is_scavengable(const void* p) {
 221   HeapRegion* hr = heap_region_containing(p);
 222   return !hr->is_pinned();
 223 }
 224 
 225 // Private methods.
 226 
 227 HeapRegion*
 228 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 229   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 230   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 231     if (!_secondary_free_list.is_empty()) {
 232       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 233                                       "secondary_free_list has %u entries",
 234                                       _secondary_free_list.length());
 235       // It looks as if there are free regions available on the
 236       // secondary_free_list. Let's move them to the free_list and try
 237       // again to allocate from it.
 238       append_secondary_free_list();
 239 
 240       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 241              "empty we should have moved at least one entry to the free_list");
 242       HeapRegion* res = _hrm.allocate_free_region(is_old);
 243       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 244                                       "allocated " HR_FORMAT " from secondary_free_list",
 245                                       HR_FORMAT_PARAMS(res));
 246       return res;
 247     }
 248 
 249     // Wait here until we get notified either when (a) there are no
 250     // more free regions coming or (b) some regions have been moved on
 251     // the secondary_free_list.
 252     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 253   }
 254 
 255   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 256                                   "could not allocate from secondary_free_list");
 257   return NULL;
 258 }
 259 
 260 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 261   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 262          "the only time we use this to allocate a humongous region is "
 263          "when we are allocating a single humongous region");
 264 
 265   HeapRegion* res;
 266   if (G1StressConcRegionFreeing) {
 267     if (!_secondary_free_list.is_empty()) {
 268       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 269                                       "forced to look at the secondary_free_list");
 270       res = new_region_try_secondary_free_list(is_old);
 271       if (res != NULL) {
 272         return res;
 273       }
 274     }
 275   }
 276 
 277   res = _hrm.allocate_free_region(is_old);
 278 
 279   if (res == NULL) {
 280     log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 281                                     "res == NULL, trying the secondary_free_list");
 282     res = new_region_try_secondary_free_list(is_old);
 283   }
 284   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 285     // Currently, only attempts to allocate GC alloc regions set
 286     // do_expand to true. So, we should only reach here during a
 287     // safepoint. If this assumption changes we might have to
 288     // reconsider the use of _expand_heap_after_alloc_failure.
 289     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 290 
 291     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 292                               word_size * HeapWordSize);
 293 
 294     if (expand(word_size * HeapWordSize)) {
 295       // Given that expand() succeeded in expanding the heap, and we
 296       // always expand the heap by an amount aligned to the heap
 297       // region size, the free list should in theory not be empty.
 298       // In either case allocate_free_region() will check for NULL.
 299       res = _hrm.allocate_free_region(is_old);
 300     } else {
 301       _expand_heap_after_alloc_failure = false;
 302     }
 303   }
 304   return res;
 305 }
 306 
 307 HeapWord*
 308 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 309                                                            uint num_regions,
 310                                                            size_t word_size,
 311                                                            AllocationContext_t context) {
 312   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 313   assert(is_humongous(word_size), "word_size should be humongous");
 314   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 315 
 316   // Index of last region in the series.
 317   uint last = first + num_regions - 1;
 318 
 319   // We need to initialize the region(s) we just discovered. This is
 320   // a bit tricky given that it can happen concurrently with
 321   // refinement threads refining cards on these regions and
 322   // potentially wanting to refine the BOT as they are scanning
 323   // those cards (this can happen shortly after a cleanup; see CR
 324   // 6991377). So we have to set up the region(s) carefully and in
 325   // a specific order.
 326 
 327   // The word size sum of all the regions we will allocate.
 328   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 329   assert(word_size <= word_size_sum, "sanity");
 330 
 331   // This will be the "starts humongous" region.
 332   HeapRegion* first_hr = region_at(first);
 333   // The header of the new object will be placed at the bottom of
 334   // the first region.
 335   HeapWord* new_obj = first_hr->bottom();
 336   // This will be the new top of the new object.
 337   HeapWord* obj_top = new_obj + word_size;
 338 
 339   // First, we need to zero the header of the space that we will be
 340   // allocating. When we update top further down, some refinement
 341   // threads might try to scan the region. By zeroing the header we
 342   // ensure that any thread that will try to scan the region will
 343   // come across the zero klass word and bail out.
 344   //
 345   // NOTE: It would not have been correct to have used
 346   // CollectedHeap::fill_with_object() and make the space look like
 347   // an int array. The thread that is doing the allocation will
 348   // later update the object header to a potentially different array
 349   // type and, for a very short period of time, the klass and length
 350   // fields will be inconsistent. This could cause a refinement
 351   // thread to calculate the object size incorrectly.
 352   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 353 
 354   // How many words we use for filler objects.
 355   size_t word_fill_size = word_size_sum - word_size;
 356 
 357   // How many words memory we "waste" which cannot hold a filler object.
 358   size_t words_not_fillable = 0;
 359 
 360   if (word_fill_size >= min_fill_size()) {
 361     fill_with_objects(obj_top, word_fill_size);
 362   } else if (word_fill_size > 0) {
 363     // We have space to fill, but we cannot fit an object there.
 364     words_not_fillable = word_fill_size;
 365     word_fill_size = 0;
 366   }
 367 
 368   // We will set up the first region as "starts humongous". This
 369   // will also update the BOT covering all the regions to reflect
 370   // that there is a single object that starts at the bottom of the
 371   // first region.
 372   first_hr->set_starts_humongous(obj_top, word_fill_size);
 373   first_hr->set_allocation_context(context);
 374   // Then, if there are any, we will set up the "continues
 375   // humongous" regions.
 376   HeapRegion* hr = NULL;
 377   for (uint i = first + 1; i <= last; ++i) {
 378     hr = region_at(i);
 379     hr->set_continues_humongous(first_hr);
 380     hr->set_allocation_context(context);
 381   }
 382 
 383   // Up to this point no concurrent thread would have been able to
 384   // do any scanning on any region in this series. All the top
 385   // fields still point to bottom, so the intersection between
 386   // [bottom,top] and [card_start,card_end] will be empty. Before we
 387   // update the top fields, we'll do a storestore to make sure that
 388   // no thread sees the update to top before the zeroing of the
 389   // object header and the BOT initialization.
 390   OrderAccess::storestore();
 391 
 392   // Now, we will update the top fields of the "continues humongous"
 393   // regions except the last one.
 394   for (uint i = first; i < last; ++i) {
 395     hr = region_at(i);
 396     hr->set_top(hr->end());
 397   }
 398 
 399   hr = region_at(last);
 400   // If we cannot fit a filler object, we must set top to the end
 401   // of the humongous object, otherwise we cannot iterate the heap
 402   // and the BOT will not be complete.
 403   hr->set_top(hr->end() - words_not_fillable);
 404 
 405   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 406          "obj_top should be in last region");
 407 
 408   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 409 
 410   assert(words_not_fillable == 0 ||
 411          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 412          "Miscalculation in humongous allocation");
 413 
 414   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 415 
 416   for (uint i = first; i <= last; ++i) {
 417     hr = region_at(i);
 418     _humongous_set.add(hr);
 419     _hr_printer.alloc(hr);
 420   }
 421 
 422   return new_obj;
 423 }
 424 
 425 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 426   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 427   return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 428 }
 429 
 430 // If could fit into free regions w/o expansion, try.
 431 // Otherwise, if can expand, do so.
 432 // Otherwise, if using ex regions might help, try with ex given back.
 433 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 434   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 435 
 436   _verifier->verify_region_sets_optional();
 437 
 438   uint first = G1_NO_HRM_INDEX;
 439   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 440 
 441   if (obj_regions == 1) {
 442     // Only one region to allocate, try to use a fast path by directly allocating
 443     // from the free lists. Do not try to expand here, we will potentially do that
 444     // later.
 445     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 446     if (hr != NULL) {
 447       first = hr->hrm_index();
 448     }
 449   } else {
 450     // We can't allocate humongous regions spanning more than one region while
 451     // cleanupComplete() is running, since some of the regions we find to be
 452     // empty might not yet be added to the free list. It is not straightforward
 453     // to know in which list they are on so that we can remove them. We only
 454     // need to do this if we need to allocate more than one region to satisfy the
 455     // current humongous allocation request. If we are only allocating one region
 456     // we use the one-region region allocation code (see above), that already
 457     // potentially waits for regions from the secondary free list.
 458     wait_while_free_regions_coming();
 459     append_secondary_free_list_if_not_empty_with_lock();
 460 
 461     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 462     // are lucky enough to find some.
 463     first = _hrm.find_contiguous_only_empty(obj_regions);
 464     if (first != G1_NO_HRM_INDEX) {
 465       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 466     }
 467   }
 468 
 469   if (first == G1_NO_HRM_INDEX) {
 470     // Policy: We could not find enough regions for the humongous object in the
 471     // free list. Look through the heap to find a mix of free and uncommitted regions.
 472     // If so, try expansion.
 473     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 474     if (first != G1_NO_HRM_INDEX) {
 475       // We found something. Make sure these regions are committed, i.e. expand
 476       // the heap. Alternatively we could do a defragmentation GC.
 477       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 478                                     word_size * HeapWordSize);
 479 
 480 
 481       _hrm.expand_at(first, obj_regions);
 482       g1_policy()->record_new_heap_size(num_regions());
 483 
 484 #ifdef ASSERT
 485       for (uint i = first; i < first + obj_regions; ++i) {
 486         HeapRegion* hr = region_at(i);
 487         assert(hr->is_free(), "sanity");
 488         assert(hr->is_empty(), "sanity");
 489         assert(is_on_master_free_list(hr), "sanity");
 490       }
 491 #endif
 492       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 493     } else {
 494       // Policy: Potentially trigger a defragmentation GC.
 495     }
 496   }
 497 
 498   HeapWord* result = NULL;
 499   if (first != G1_NO_HRM_INDEX) {
 500     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 501                                                        word_size, context);
 502     assert(result != NULL, "it should always return a valid result");
 503 
 504     // A successful humongous object allocation changes the used space
 505     // information of the old generation so we need to recalculate the
 506     // sizes and update the jstat counters here.
 507     g1mm()->update_sizes();
 508   }
 509 
 510   _verifier->verify_region_sets_optional();
 511 
 512   return result;
 513 }
 514 
 515 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 516   assert_heap_not_locked_and_not_at_safepoint();
 517   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 518 
 519   uint dummy_gc_count_before;
 520   uint dummy_gclocker_retry_count = 0;
 521   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 522 }
 523 
 524 HeapWord*
 525 G1CollectedHeap::mem_allocate(size_t word_size,
 526                               bool*  gc_overhead_limit_was_exceeded) {
 527   assert_heap_not_locked_and_not_at_safepoint();
 528 
 529   // Loop until the allocation is satisfied, or unsatisfied after GC.
 530   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 531     uint gc_count_before;
 532 
 533     HeapWord* result = NULL;
 534     if (!is_humongous(word_size)) {
 535       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 536     } else {
 537       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 538     }
 539     if (result != NULL) {
 540       return result;
 541     }
 542 
 543     // Create the garbage collection operation...
 544     VM_G1CollectForAllocation op(gc_count_before, word_size);
 545     op.set_allocation_context(AllocationContext::current());
 546 
 547     // ...and get the VM thread to execute it.
 548     VMThread::execute(&op);
 549 
 550     if (op.prologue_succeeded() && op.pause_succeeded()) {
 551       // If the operation was successful we'll return the result even
 552       // if it is NULL. If the allocation attempt failed immediately
 553       // after a Full GC, it's unlikely we'll be able to allocate now.
 554       HeapWord* result = op.result();
 555       if (result != NULL && !is_humongous(word_size)) {
 556         // Allocations that take place on VM operations do not do any
 557         // card dirtying and we have to do it here. We only have to do
 558         // this for non-humongous allocations, though.
 559         dirty_young_block(result, word_size);
 560       }
 561       return result;
 562     } else {
 563       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 564         return NULL;
 565       }
 566       assert(op.result() == NULL,
 567              "the result should be NULL if the VM op did not succeed");
 568     }
 569 
 570     // Give a warning if we seem to be looping forever.
 571     if ((QueuedAllocationWarningCount > 0) &&
 572         (try_count % QueuedAllocationWarningCount == 0)) {
 573       log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
 574     }
 575   }
 576 
 577   ShouldNotReachHere();
 578   return NULL;
 579 }
 580 
 581 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 582                                                    AllocationContext_t context,
 583                                                    uint* gc_count_before_ret,
 584                                                    uint* gclocker_retry_count_ret) {
 585   // Make sure you read the note in attempt_allocation_humongous().
 586 
 587   assert_heap_not_locked_and_not_at_safepoint();
 588   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 589          "be called for humongous allocation requests");
 590 
 591   // We should only get here after the first-level allocation attempt
 592   // (attempt_allocation()) failed to allocate.
 593 
 594   // We will loop until a) we manage to successfully perform the
 595   // allocation or b) we successfully schedule a collection which
 596   // fails to perform the allocation. b) is the only case when we'll
 597   // return NULL.
 598   HeapWord* result = NULL;
 599   for (int try_count = 1; /* we'll return */; try_count += 1) {
 600     bool should_try_gc;
 601     uint gc_count_before;
 602 
 603     {
 604       MutexLockerEx x(Heap_lock);
 605       result = _allocator->attempt_allocation_locked(word_size, context);
 606       if (result != NULL) {
 607         return result;
 608       }
 609 
 610       if (GCLocker::is_active_and_needs_gc()) {
 611         if (g1_policy()->can_expand_young_list()) {
 612           // No need for an ergo verbose message here,
 613           // can_expand_young_list() does this when it returns true.
 614           result = _allocator->attempt_allocation_force(word_size, context);
 615           if (result != NULL) {
 616             return result;
 617           }
 618         }
 619         should_try_gc = false;
 620       } else {
 621         // The GCLocker may not be active but the GCLocker initiated
 622         // GC may not yet have been performed (GCLocker::needs_gc()
 623         // returns true). In this case we do not try this GC and
 624         // wait until the GCLocker initiated GC is performed, and
 625         // then retry the allocation.
 626         if (GCLocker::needs_gc()) {
 627           should_try_gc = false;
 628         } else {
 629           // Read the GC count while still holding the Heap_lock.
 630           gc_count_before = total_collections();
 631           should_try_gc = true;
 632         }
 633       }
 634     }
 635 
 636     if (should_try_gc) {
 637       bool succeeded;
 638       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 639                                    GCCause::_g1_inc_collection_pause);
 640       if (result != NULL) {
 641         assert(succeeded, "only way to get back a non-NULL result");
 642         return result;
 643       }
 644 
 645       if (succeeded) {
 646         // If we get here we successfully scheduled a collection which
 647         // failed to allocate. No point in trying to allocate
 648         // further. We'll just return NULL.
 649         MutexLockerEx x(Heap_lock);
 650         *gc_count_before_ret = total_collections();
 651         return NULL;
 652       }
 653     } else {
 654       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 655         MutexLockerEx x(Heap_lock);
 656         *gc_count_before_ret = total_collections();
 657         return NULL;
 658       }
 659       // The GCLocker is either active or the GCLocker initiated
 660       // GC has not yet been performed. Stall until it is and
 661       // then retry the allocation.
 662       GCLocker::stall_until_clear();
 663       (*gclocker_retry_count_ret) += 1;
 664     }
 665 
 666     // We can reach here if we were unsuccessful in scheduling a
 667     // collection (because another thread beat us to it) or if we were
 668     // stalled due to the GC locker. In either can we should retry the
 669     // allocation attempt in case another thread successfully
 670     // performed a collection and reclaimed enough space. We do the
 671     // first attempt (without holding the Heap_lock) here and the
 672     // follow-on attempt will be at the start of the next loop
 673     // iteration (after taking the Heap_lock).
 674     result = _allocator->attempt_allocation(word_size, context);
 675     if (result != NULL) {
 676       return result;
 677     }
 678 
 679     // Give a warning if we seem to be looping forever.
 680     if ((QueuedAllocationWarningCount > 0) &&
 681         (try_count % QueuedAllocationWarningCount == 0)) {
 682       log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
 683                       "retries %d times", try_count);
 684     }
 685   }
 686 
 687   ShouldNotReachHere();
 688   return NULL;
 689 }
 690 
 691 void G1CollectedHeap::begin_archive_alloc_range() {
 692   assert_at_safepoint(true /* should_be_vm_thread */);
 693   if (_archive_allocator == NULL) {
 694     _archive_allocator = G1ArchiveAllocator::create_allocator(this);
 695   }
 696 }
 697 
 698 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 699   // Allocations in archive regions cannot be of a size that would be considered
 700   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 701   // may be different at archive-restore time.
 702   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 703 }
 704 
 705 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 706   assert_at_safepoint(true /* should_be_vm_thread */);
 707   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 708   if (is_archive_alloc_too_large(word_size)) {
 709     return NULL;
 710   }
 711   return _archive_allocator->archive_mem_allocate(word_size);
 712 }
 713 
 714 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 715                                               size_t end_alignment_in_bytes) {
 716   assert_at_safepoint(true /* should_be_vm_thread */);
 717   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 718 
 719   // Call complete_archive to do the real work, filling in the MemRegion
 720   // array with the archive regions.
 721   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 722   delete _archive_allocator;
 723   _archive_allocator = NULL;
 724 }
 725 
 726 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 727   assert(ranges != NULL, "MemRegion array NULL");
 728   assert(count != 0, "No MemRegions provided");
 729   MemRegion reserved = _hrm.reserved();
 730   for (size_t i = 0; i < count; i++) {
 731     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 732       return false;
 733     }
 734   }
 735   return true;
 736 }
 737 
 738 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
 739   assert(!is_init_completed(), "Expect to be called at JVM init time");
 740   assert(ranges != NULL, "MemRegion array NULL");
 741   assert(count != 0, "No MemRegions provided");
 742   MutexLockerEx x(Heap_lock);
 743 
 744   MemRegion reserved = _hrm.reserved();
 745   HeapWord* prev_last_addr = NULL;
 746   HeapRegion* prev_last_region = NULL;
 747 
 748   // Temporarily disable pretouching of heap pages. This interface is used
 749   // when mmap'ing archived heap data in, so pre-touching is wasted.
 750   FlagSetting fs(AlwaysPreTouch, false);
 751 
 752   // Enable archive object checking in G1MarkSweep. We have to let it know
 753   // about each archive range, so that objects in those ranges aren't marked.
 754   G1MarkSweep::enable_archive_object_check();
 755 
 756   // For each specified MemRegion range, allocate the corresponding G1
 757   // regions and mark them as archive regions. We expect the ranges in
 758   // ascending starting address order, without overlap.
 759   for (size_t i = 0; i < count; i++) {
 760     MemRegion curr_range = ranges[i];
 761     HeapWord* start_address = curr_range.start();
 762     size_t word_size = curr_range.word_size();
 763     HeapWord* last_address = curr_range.last();
 764     size_t commits = 0;
 765 
 766     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 767               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 768               p2i(start_address), p2i(last_address));
 769     guarantee(start_address > prev_last_addr,
 770               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 771               p2i(start_address), p2i(prev_last_addr));
 772     prev_last_addr = last_address;
 773 
 774     // Check for ranges that start in the same G1 region in which the previous
 775     // range ended, and adjust the start address so we don't try to allocate
 776     // the same region again. If the current range is entirely within that
 777     // region, skip it, just adjusting the recorded top.
 778     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 779     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 780       start_address = start_region->end();
 781       if (start_address > last_address) {
 782         increase_used(word_size * HeapWordSize);
 783         start_region->set_top(last_address + 1);
 784         continue;
 785       }
 786       start_region->set_top(start_address);
 787       curr_range = MemRegion(start_address, last_address + 1);
 788       start_region = _hrm.addr_to_region(start_address);
 789     }
 790 
 791     // Perform the actual region allocation, exiting if it fails.
 792     // Then note how much new space we have allocated.
 793     if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
 794       return false;
 795     }
 796     increase_used(word_size * HeapWordSize);
 797     if (commits != 0) {
 798       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 799                                 HeapRegion::GrainWords * HeapWordSize * commits);
 800 
 801     }
 802 
 803     // Mark each G1 region touched by the range as archive, add it to the old set,
 804     // and set the allocation context and top.
 805     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 806     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 807     prev_last_region = last_region;
 808 
 809     while (curr_region != NULL) {
 810       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 811              "Region already in use (index %u)", curr_region->hrm_index());
 812       curr_region->set_allocation_context(AllocationContext::system());
 813       curr_region->set_archive();
 814       _hr_printer.alloc(curr_region);
 815       _old_set.add(curr_region);
 816       if (curr_region != last_region) {
 817         curr_region->set_top(curr_region->end());
 818         curr_region = _hrm.next_region_in_heap(curr_region);
 819       } else {
 820         curr_region->set_top(last_address + 1);
 821         curr_region = NULL;
 822       }
 823     }
 824 
 825     // Notify mark-sweep of the archive range.
 826     G1MarkSweep::set_range_archive(curr_range, true);
 827   }
 828   return true;
 829 }
 830 
 831 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 832   assert(!is_init_completed(), "Expect to be called at JVM init time");
 833   assert(ranges != NULL, "MemRegion array NULL");
 834   assert(count != 0, "No MemRegions provided");
 835   MemRegion reserved = _hrm.reserved();
 836   HeapWord *prev_last_addr = NULL;
 837   HeapRegion* prev_last_region = NULL;
 838 
 839   // For each MemRegion, create filler objects, if needed, in the G1 regions
 840   // that contain the address range. The address range actually within the
 841   // MemRegion will not be modified. That is assumed to have been initialized
 842   // elsewhere, probably via an mmap of archived heap data.
 843   MutexLockerEx x(Heap_lock);
 844   for (size_t i = 0; i < count; i++) {
 845     HeapWord* start_address = ranges[i].start();
 846     HeapWord* last_address = ranges[i].last();
 847 
 848     assert(reserved.contains(start_address) && reserved.contains(last_address),
 849            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 850            p2i(start_address), p2i(last_address));
 851     assert(start_address > prev_last_addr,
 852            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 853            p2i(start_address), p2i(prev_last_addr));
 854 
 855     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 856     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 857     HeapWord* bottom_address = start_region->bottom();
 858 
 859     // Check for a range beginning in the same region in which the
 860     // previous one ended.
 861     if (start_region == prev_last_region) {
 862       bottom_address = prev_last_addr + 1;
 863     }
 864 
 865     // Verify that the regions were all marked as archive regions by
 866     // alloc_archive_regions.
 867     HeapRegion* curr_region = start_region;
 868     while (curr_region != NULL) {
 869       guarantee(curr_region->is_archive(),
 870                 "Expected archive region at index %u", curr_region->hrm_index());
 871       if (curr_region != last_region) {
 872         curr_region = _hrm.next_region_in_heap(curr_region);
 873       } else {
 874         curr_region = NULL;
 875       }
 876     }
 877 
 878     prev_last_addr = last_address;
 879     prev_last_region = last_region;
 880 
 881     // Fill the memory below the allocated range with dummy object(s),
 882     // if the region bottom does not match the range start, or if the previous
 883     // range ended within the same G1 region, and there is a gap.
 884     if (start_address != bottom_address) {
 885       size_t fill_size = pointer_delta(start_address, bottom_address);
 886       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 887       increase_used(fill_size * HeapWordSize);
 888     }
 889   }
 890 }
 891 
 892 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
 893                                                      uint* gc_count_before_ret,
 894                                                      uint* gclocker_retry_count_ret) {
 895   assert_heap_not_locked_and_not_at_safepoint();
 896   assert(!is_humongous(word_size), "attempt_allocation() should not "
 897          "be called for humongous allocation requests");
 898 
 899   AllocationContext_t context = AllocationContext::current();
 900   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 901 
 902   if (result == NULL) {
 903     result = attempt_allocation_slow(word_size,
 904                                      context,
 905                                      gc_count_before_ret,
 906                                      gclocker_retry_count_ret);
 907   }
 908   assert_heap_not_locked();
 909   if (result != NULL) {
 910     dirty_young_block(result, word_size);
 911   }
 912   return result;
 913 }
 914 
 915 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 916   assert(!is_init_completed(), "Expect to be called at JVM init time");
 917   assert(ranges != NULL, "MemRegion array NULL");
 918   assert(count != 0, "No MemRegions provided");
 919   MemRegion reserved = _hrm.reserved();
 920   HeapWord* prev_last_addr = NULL;
 921   HeapRegion* prev_last_region = NULL;
 922   size_t size_used = 0;
 923   size_t uncommitted_regions = 0;
 924 
 925   // For each Memregion, free the G1 regions that constitute it, and
 926   // notify mark-sweep that the range is no longer to be considered 'archive.'
 927   MutexLockerEx x(Heap_lock);
 928   for (size_t i = 0; i < count; i++) {
 929     HeapWord* start_address = ranges[i].start();
 930     HeapWord* last_address = ranges[i].last();
 931 
 932     assert(reserved.contains(start_address) && reserved.contains(last_address),
 933            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 934            p2i(start_address), p2i(last_address));
 935     assert(start_address > prev_last_addr,
 936            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 937            p2i(start_address), p2i(prev_last_addr));
 938     size_used += ranges[i].byte_size();
 939     prev_last_addr = last_address;
 940 
 941     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 942     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 943 
 944     // Check for ranges that start in the same G1 region in which the previous
 945     // range ended, and adjust the start address so we don't try to free
 946     // the same region again. If the current range is entirely within that
 947     // region, skip it.
 948     if (start_region == prev_last_region) {
 949       start_address = start_region->end();
 950       if (start_address > last_address) {
 951         continue;
 952       }
 953       start_region = _hrm.addr_to_region(start_address);
 954     }
 955     prev_last_region = last_region;
 956 
 957     // After verifying that each region was marked as an archive region by
 958     // alloc_archive_regions, set it free and empty and uncommit it.
 959     HeapRegion* curr_region = start_region;
 960     while (curr_region != NULL) {
 961       guarantee(curr_region->is_archive(),
 962                 "Expected archive region at index %u", curr_region->hrm_index());
 963       uint curr_index = curr_region->hrm_index();
 964       _old_set.remove(curr_region);
 965       curr_region->set_free();
 966       curr_region->set_top(curr_region->bottom());
 967       if (curr_region != last_region) {
 968         curr_region = _hrm.next_region_in_heap(curr_region);
 969       } else {
 970         curr_region = NULL;
 971       }
 972       _hrm.shrink_at(curr_index, 1);
 973       uncommitted_regions++;
 974     }
 975 
 976     // Notify mark-sweep that this is no longer an archive range.
 977     G1MarkSweep::set_range_archive(ranges[i], false);
 978   }
 979 
 980   if (uncommitted_regions != 0) {
 981     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 982                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 983   }
 984   decrease_used(size_used);
 985 }
 986 
 987 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 988                                                         uint* gc_count_before_ret,
 989                                                         uint* gclocker_retry_count_ret) {
 990   // The structure of this method has a lot of similarities to
 991   // attempt_allocation_slow(). The reason these two were not merged
 992   // into a single one is that such a method would require several "if
 993   // allocation is not humongous do this, otherwise do that"
 994   // conditional paths which would obscure its flow. In fact, an early
 995   // version of this code did use a unified method which was harder to
 996   // follow and, as a result, it had subtle bugs that were hard to
 997   // track down. So keeping these two methods separate allows each to
 998   // be more readable. It will be good to keep these two in sync as
 999   // much as possible.
1000 
1001   assert_heap_not_locked_and_not_at_safepoint();
1002   assert(is_humongous(word_size), "attempt_allocation_humongous() "
1003          "should only be called for humongous allocations");
1004 
1005   // Humongous objects can exhaust the heap quickly, so we should check if we
1006   // need to start a marking cycle at each humongous object allocation. We do
1007   // the check before we do the actual allocation. The reason for doing it
1008   // before the allocation is that we avoid having to keep track of the newly
1009   // allocated memory while we do a GC.
1010   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1011                                            word_size)) {
1012     collect(GCCause::_g1_humongous_allocation);
1013   }
1014 
1015   // We will loop until a) we manage to successfully perform the
1016   // allocation or b) we successfully schedule a collection which
1017   // fails to perform the allocation. b) is the only case when we'll
1018   // return NULL.
1019   HeapWord* result = NULL;
1020   for (int try_count = 1; /* we'll return */; try_count += 1) {
1021     bool should_try_gc;
1022     uint gc_count_before;
1023 
1024     {
1025       MutexLockerEx x(Heap_lock);
1026 
1027       // Given that humongous objects are not allocated in young
1028       // regions, we'll first try to do the allocation without doing a
1029       // collection hoping that there's enough space in the heap.
1030       result = humongous_obj_allocate(word_size, AllocationContext::current());
1031       if (result != NULL) {
1032         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1033         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1034         return result;
1035       }
1036 
1037       if (GCLocker::is_active_and_needs_gc()) {
1038         should_try_gc = false;
1039       } else {
1040          // The GCLocker may not be active but the GCLocker initiated
1041         // GC may not yet have been performed (GCLocker::needs_gc()
1042         // returns true). In this case we do not try this GC and
1043         // wait until the GCLocker initiated GC is performed, and
1044         // then retry the allocation.
1045         if (GCLocker::needs_gc()) {
1046           should_try_gc = false;
1047         } else {
1048           // Read the GC count while still holding the Heap_lock.
1049           gc_count_before = total_collections();
1050           should_try_gc = true;
1051         }
1052       }
1053     }
1054 
1055     if (should_try_gc) {
1056       // If we failed to allocate the humongous object, we should try to
1057       // do a collection pause (if we're allowed) in case it reclaims
1058       // enough space for the allocation to succeed after the pause.
1059 
1060       bool succeeded;
1061       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1062                                    GCCause::_g1_humongous_allocation);
1063       if (result != NULL) {
1064         assert(succeeded, "only way to get back a non-NULL result");
1065         return result;
1066       }
1067 
1068       if (succeeded) {
1069         // If we get here we successfully scheduled a collection which
1070         // failed to allocate. No point in trying to allocate
1071         // further. We'll just return NULL.
1072         MutexLockerEx x(Heap_lock);
1073         *gc_count_before_ret = total_collections();
1074         return NULL;
1075       }
1076     } else {
1077       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1078         MutexLockerEx x(Heap_lock);
1079         *gc_count_before_ret = total_collections();
1080         return NULL;
1081       }
1082       // The GCLocker is either active or the GCLocker initiated
1083       // GC has not yet been performed. Stall until it is and
1084       // then retry the allocation.
1085       GCLocker::stall_until_clear();
1086       (*gclocker_retry_count_ret) += 1;
1087     }
1088 
1089     // We can reach here if we were unsuccessful in scheduling a
1090     // collection (because another thread beat us to it) or if we were
1091     // stalled due to the GC locker. In either can we should retry the
1092     // allocation attempt in case another thread successfully
1093     // performed a collection and reclaimed enough space.  Give a
1094     // warning if we seem to be looping forever.
1095 
1096     if ((QueuedAllocationWarningCount > 0) &&
1097         (try_count % QueuedAllocationWarningCount == 0)) {
1098       log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1099                       "retries %d times", try_count);
1100     }
1101   }
1102 
1103   ShouldNotReachHere();
1104   return NULL;
1105 }
1106 
1107 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1108                                                            AllocationContext_t context,
1109                                                            bool expect_null_mutator_alloc_region) {
1110   assert_at_safepoint(true /* should_be_vm_thread */);
1111   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1112          "the current alloc region was unexpectedly found to be non-NULL");
1113 
1114   if (!is_humongous(word_size)) {
1115     return _allocator->attempt_allocation_locked(word_size, context);
1116   } else {
1117     HeapWord* result = humongous_obj_allocate(word_size, context);
1118     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1119       collector_state()->set_initiate_conc_mark_if_possible(true);
1120     }
1121     return result;
1122   }
1123 
1124   ShouldNotReachHere();
1125 }
1126 
1127 class PostMCRemSetClearClosure: public HeapRegionClosure {
1128   G1CollectedHeap* _g1h;
1129   ModRefBarrierSet* _mr_bs;
1130 public:
1131   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1132     _g1h(g1h), _mr_bs(mr_bs) {}
1133 
1134   bool doHeapRegion(HeapRegion* r) {
1135     HeapRegionRemSet* hrrs = r->rem_set();
1136 
1137     _g1h->reset_gc_time_stamps(r);
1138 
1139     if (r->is_continues_humongous()) {
1140       // We'll assert that the strong code root list and RSet is empty
1141       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1142       assert(hrrs->occupied() == 0, "RSet should be empty");
1143     } else {
1144       hrrs->clear();
1145     }
1146     // You might think here that we could clear just the cards
1147     // corresponding to the used region.  But no: if we leave a dirty card
1148     // in a region we might allocate into, then it would prevent that card
1149     // from being enqueued, and cause it to be missed.
1150     // Re: the performance cost: we shouldn't be doing full GC anyway!
1151     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1152 
1153     return false;
1154   }
1155 };
1156 
1157 void G1CollectedHeap::clear_rsets_post_compaction() {
1158   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1159   heap_region_iterate(&rs_clear);
1160 }
1161 
1162 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1163   G1CollectedHeap*   _g1h;
1164   UpdateRSOopClosure _cl;
1165 public:
1166   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1167     _cl(g1->g1_rem_set(), worker_i),
1168     _g1h(g1)
1169   { }
1170 
1171   bool doHeapRegion(HeapRegion* r) {
1172     if (!r->is_continues_humongous()) {
1173       _cl.set_from(r);
1174       r->oop_iterate(&_cl);
1175     }
1176     return false;
1177   }
1178 };
1179 
1180 class ParRebuildRSTask: public AbstractGangTask {
1181   G1CollectedHeap* _g1;
1182   HeapRegionClaimer _hrclaimer;
1183 
1184 public:
1185   ParRebuildRSTask(G1CollectedHeap* g1) :
1186       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1187 
1188   void work(uint worker_id) {
1189     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1190     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1191   }
1192 };
1193 
1194 class PostCompactionPrinterClosure: public HeapRegionClosure {
1195 private:
1196   G1HRPrinter* _hr_printer;
1197 public:
1198   bool doHeapRegion(HeapRegion* hr) {
1199     assert(!hr->is_young(), "not expecting to find young regions");
1200     _hr_printer->post_compaction(hr);
1201     return false;
1202   }
1203 
1204   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1205     : _hr_printer(hr_printer) { }
1206 };
1207 
1208 void G1CollectedHeap::print_hrm_post_compaction() {
1209   if (_hr_printer.is_active()) {
1210     PostCompactionPrinterClosure cl(hr_printer());
1211     heap_region_iterate(&cl);
1212   }
1213 
1214 }
1215 
1216 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1217                                          bool clear_all_soft_refs) {
1218   assert_at_safepoint(true /* should_be_vm_thread */);
1219 
1220   if (GCLocker::check_active_before_gc()) {
1221     return false;
1222   }
1223 
1224   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1225   gc_timer->register_gc_start();
1226 
1227   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1228   GCIdMark gc_id_mark;
1229   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1230 
1231   SvcGCMarker sgcm(SvcGCMarker::FULL);
1232   ResourceMark rm;
1233 
1234   print_heap_before_gc();
1235   print_heap_regions();
1236   trace_heap_before_gc(gc_tracer);
1237 
1238   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1239 
1240   _verifier->verify_region_sets_optional();
1241 
1242   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1243                            collector_policy()->should_clear_all_soft_refs();
1244 
1245   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1246 
1247   {
1248     IsGCActiveMark x;
1249 
1250     // Timing
1251     assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1252     GCTraceCPUTime tcpu;
1253 
1254     {
1255       GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1256       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1257       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1258 
1259       G1HeapTransition heap_transition(this);
1260       g1_policy()->record_full_collection_start();
1261 
1262       // Note: When we have a more flexible GC logging framework that
1263       // allows us to add optional attributes to a GC log record we
1264       // could consider timing and reporting how long we wait in the
1265       // following two methods.
1266       wait_while_free_regions_coming();
1267       // If we start the compaction before the CM threads finish
1268       // scanning the root regions we might trip them over as we'll
1269       // be moving objects / updating references. So let's wait until
1270       // they are done. By telling them to abort, they should complete
1271       // early.
1272       _cm->root_regions()->abort();
1273       _cm->root_regions()->wait_until_scan_finished();
1274       append_secondary_free_list_if_not_empty_with_lock();
1275 
1276       gc_prologue(true);
1277       increment_total_collections(true /* full gc */);
1278       increment_old_marking_cycles_started();
1279 
1280       assert(used() == recalculate_used(), "Should be equal");
1281 
1282       _verifier->verify_before_gc();
1283 
1284       _verifier->check_bitmaps("Full GC Start");
1285       pre_full_gc_dump(gc_timer);
1286 
1287 #if defined(COMPILER2) || INCLUDE_JVMCI
1288       DerivedPointerTable::clear();
1289 #endif
1290 
1291       // Disable discovery and empty the discovered lists
1292       // for the CM ref processor.
1293       ref_processor_cm()->disable_discovery();
1294       ref_processor_cm()->abandon_partial_discovery();
1295       ref_processor_cm()->verify_no_references_recorded();
1296 
1297       // Abandon current iterations of concurrent marking and concurrent
1298       // refinement, if any are in progress.
1299       concurrent_mark()->abort();
1300 
1301       // Make sure we'll choose a new allocation region afterwards.
1302       _allocator->release_mutator_alloc_region();
1303       _allocator->abandon_gc_alloc_regions();
1304       g1_rem_set()->cleanupHRRS();
1305 
1306       // We may have added regions to the current incremental collection
1307       // set between the last GC or pause and now. We need to clear the
1308       // incremental collection set and then start rebuilding it afresh
1309       // after this full GC.
1310       abandon_collection_set(collection_set()->inc_head());
1311       collection_set()->clear_incremental();
1312       collection_set()->stop_incremental_building();
1313 
1314       tear_down_region_sets(false /* free_list_only */);
1315       collector_state()->set_gcs_are_young(true);
1316 
1317       // See the comments in g1CollectedHeap.hpp and
1318       // G1CollectedHeap::ref_processing_init() about
1319       // how reference processing currently works in G1.
1320 
1321       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1322       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1323 
1324       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1325       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1326 
1327       ref_processor_stw()->enable_discovery();
1328       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1329 
1330       // Do collection work
1331       {
1332         HandleMark hm;  // Discard invalid handles created during gc
1333         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1334       }
1335 
1336       assert(num_free_regions() == 0, "we should not have added any free regions");
1337       rebuild_region_sets(false /* free_list_only */);
1338 
1339       // Enqueue any discovered reference objects that have
1340       // not been removed from the discovered lists.
1341       ref_processor_stw()->enqueue_discovered_references();
1342 
1343 #if defined(COMPILER2) || INCLUDE_JVMCI
1344       DerivedPointerTable::update_pointers();
1345 #endif
1346 
1347       MemoryService::track_memory_usage();
1348 
1349       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1350       ref_processor_stw()->verify_no_references_recorded();
1351 
1352       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1353       ClassLoaderDataGraph::purge();
1354       MetaspaceAux::verify_metrics();
1355 
1356       // Note: since we've just done a full GC, concurrent
1357       // marking is no longer active. Therefore we need not
1358       // re-enable reference discovery for the CM ref processor.
1359       // That will be done at the start of the next marking cycle.
1360       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1361       ref_processor_cm()->verify_no_references_recorded();
1362 
1363       reset_gc_time_stamp();
1364       // Since everything potentially moved, we will clear all remembered
1365       // sets, and clear all cards.  Later we will rebuild remembered
1366       // sets. We will also reset the GC time stamps of the regions.
1367       clear_rsets_post_compaction();
1368       check_gc_time_stamps();
1369 
1370       resize_if_necessary_after_full_collection();
1371 
1372       // We should do this after we potentially resize the heap so
1373       // that all the COMMIT / UNCOMMIT events are generated before
1374       // the compaction events.
1375       print_hrm_post_compaction();
1376 
1377       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1378       if (hot_card_cache->use_cache()) {
1379         hot_card_cache->reset_card_counts();
1380         hot_card_cache->reset_hot_cache();
1381       }
1382 
1383       // Rebuild remembered sets of all regions.
1384       uint n_workers =
1385         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1386                                                 workers()->active_workers(),
1387                                                 Threads::number_of_non_daemon_threads());
1388       workers()->set_active_workers(n_workers);
1389 
1390       ParRebuildRSTask rebuild_rs_task(this);
1391       workers()->run_task(&rebuild_rs_task);
1392 
1393       // Rebuild the strong code root lists for each region
1394       rebuild_strong_code_roots();
1395 
1396       if (true) { // FIXME
1397         MetaspaceGC::compute_new_size();
1398       }
1399 
1400 #ifdef TRACESPINNING
1401       ParallelTaskTerminator::print_termination_counts();
1402 #endif
1403 
1404       // Discard all rset updates
1405       JavaThread::dirty_card_queue_set().abandon_logs();
1406       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1407 
1408       // At this point there should be no regions in the
1409       // entire heap tagged as young.
1410       assert(check_young_list_empty(true /* check_heap */),
1411              "young list should be empty at this point");
1412 
1413       // Update the number of full collections that have been completed.
1414       increment_old_marking_cycles_completed(false /* concurrent */);
1415 
1416       _hrm.verify_optional();
1417       _verifier->verify_region_sets_optional();
1418 
1419       _verifier->verify_after_gc();
1420 
1421       // Clear the previous marking bitmap, if needed for bitmap verification.
1422       // Note we cannot do this when we clear the next marking bitmap in
1423       // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1424       // objects marked during a full GC against the previous bitmap.
1425       // But we need to clear it before calling check_bitmaps below since
1426       // the full GC has compacted objects and updated TAMS but not updated
1427       // the prev bitmap.
1428       if (G1VerifyBitmaps) {
1429         GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1430         _cm->clear_prev_bitmap(workers());
1431       }
1432       _verifier->check_bitmaps("Full GC End");
1433 
1434       // Start a new incremental collection set for the next pause
1435       assert(collection_set()->head() == NULL, "must be");
1436       collection_set()->start_incremental_building();
1437 
1438       clear_cset_fast_test();
1439 
1440       _allocator->init_mutator_alloc_region();
1441 
1442       g1_policy()->record_full_collection_end();
1443 
1444       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1445       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1446       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1447       // before any GC notifications are raised.
1448       g1mm()->update_sizes();
1449 
1450       gc_epilogue(true);
1451 
1452       heap_transition.print();
1453 
1454       print_heap_after_gc();
1455       print_heap_regions();
1456       trace_heap_after_gc(gc_tracer);
1457 
1458       post_full_gc_dump(gc_timer);
1459     }
1460 
1461     gc_timer->register_gc_end();
1462     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1463   }
1464 
1465   return true;
1466 }
1467 
1468 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1469   // Currently, there is no facility in the do_full_collection(bool) API to notify
1470   // the caller that the collection did not succeed (e.g., because it was locked
1471   // out by the GC locker). So, right now, we'll ignore the return value.
1472   bool dummy = do_full_collection(true,                /* explicit_gc */
1473                                   clear_all_soft_refs);
1474 }
1475 
1476 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1477   // Include bytes that will be pre-allocated to support collections, as "used".
1478   const size_t used_after_gc = used();
1479   const size_t capacity_after_gc = capacity();
1480   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1481 
1482   // This is enforced in arguments.cpp.
1483   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1484          "otherwise the code below doesn't make sense");
1485 
1486   // We don't have floating point command-line arguments
1487   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1488   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1489   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1490   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1491 
1492   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1493   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1494 
1495   // We have to be careful here as these two calculations can overflow
1496   // 32-bit size_t's.
1497   double used_after_gc_d = (double) used_after_gc;
1498   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1499   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1500 
1501   // Let's make sure that they are both under the max heap size, which
1502   // by default will make them fit into a size_t.
1503   double desired_capacity_upper_bound = (double) max_heap_size;
1504   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1505                                     desired_capacity_upper_bound);
1506   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1507                                     desired_capacity_upper_bound);
1508 
1509   // We can now safely turn them into size_t's.
1510   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1511   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1512 
1513   // This assert only makes sense here, before we adjust them
1514   // with respect to the min and max heap size.
1515   assert(minimum_desired_capacity <= maximum_desired_capacity,
1516          "minimum_desired_capacity = " SIZE_FORMAT ", "
1517          "maximum_desired_capacity = " SIZE_FORMAT,
1518          minimum_desired_capacity, maximum_desired_capacity);
1519 
1520   // Should not be greater than the heap max size. No need to adjust
1521   // it with respect to the heap min size as it's a lower bound (i.e.,
1522   // we'll try to make the capacity larger than it, not smaller).
1523   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1524   // Should not be less than the heap min size. No need to adjust it
1525   // with respect to the heap max size as it's an upper bound (i.e.,
1526   // we'll try to make the capacity smaller than it, not greater).
1527   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1528 
1529   if (capacity_after_gc < minimum_desired_capacity) {
1530     // Don't expand unless it's significant
1531     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1532 
1533     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1534                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1535                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1536 
1537     expand(expand_bytes);
1538 
1539     // No expansion, now see if we want to shrink
1540   } else if (capacity_after_gc > maximum_desired_capacity) {
1541     // Capacity too large, compute shrinking size
1542     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1543 
1544     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1545                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1546                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1547 
1548     shrink(shrink_bytes);
1549   }
1550 }
1551 
1552 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1553                                                             AllocationContext_t context,
1554                                                             bool do_gc,
1555                                                             bool clear_all_soft_refs,
1556                                                             bool expect_null_mutator_alloc_region,
1557                                                             bool* gc_succeeded) {
1558   *gc_succeeded = true;
1559   // Let's attempt the allocation first.
1560   HeapWord* result =
1561     attempt_allocation_at_safepoint(word_size,
1562                                     context,
1563                                     expect_null_mutator_alloc_region);
1564   if (result != NULL) {
1565     assert(*gc_succeeded, "sanity");
1566     return result;
1567   }
1568 
1569   // In a G1 heap, we're supposed to keep allocation from failing by
1570   // incremental pauses.  Therefore, at least for now, we'll favor
1571   // expansion over collection.  (This might change in the future if we can
1572   // do something smarter than full collection to satisfy a failed alloc.)
1573   result = expand_and_allocate(word_size, context);
1574   if (result != NULL) {
1575     assert(*gc_succeeded, "sanity");
1576     return result;
1577   }
1578 
1579   if (do_gc) {
1580     // Expansion didn't work, we'll try to do a Full GC.
1581     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1582                                        clear_all_soft_refs);
1583   }
1584 
1585   return NULL;
1586 }
1587 
1588 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1589                                                      AllocationContext_t context,
1590                                                      bool* succeeded) {
1591   assert_at_safepoint(true /* should_be_vm_thread */);
1592 
1593   // Attempts to allocate followed by Full GC.
1594   HeapWord* result =
1595     satisfy_failed_allocation_helper(word_size,
1596                                      context,
1597                                      true,  /* do_gc */
1598                                      false, /* clear_all_soft_refs */
1599                                      false, /* expect_null_mutator_alloc_region */
1600                                      succeeded);
1601 
1602   if (result != NULL || !*succeeded) {
1603     return result;
1604   }
1605 
1606   // Attempts to allocate followed by Full GC that will collect all soft references.
1607   result = satisfy_failed_allocation_helper(word_size,
1608                                             context,
1609                                             true, /* do_gc */
1610                                             true, /* clear_all_soft_refs */
1611                                             true, /* expect_null_mutator_alloc_region */
1612                                             succeeded);
1613 
1614   if (result != NULL || !*succeeded) {
1615     return result;
1616   }
1617 
1618   // Attempts to allocate, no GC
1619   result = satisfy_failed_allocation_helper(word_size,
1620                                             context,
1621                                             false, /* do_gc */
1622                                             false, /* clear_all_soft_refs */
1623                                             true,  /* expect_null_mutator_alloc_region */
1624                                             succeeded);
1625 
1626   if (result != NULL) {
1627     assert(*succeeded, "sanity");
1628     return result;
1629   }
1630 
1631   assert(!collector_policy()->should_clear_all_soft_refs(),
1632          "Flag should have been handled and cleared prior to this point");
1633 
1634   // What else?  We might try synchronous finalization later.  If the total
1635   // space available is large enough for the allocation, then a more
1636   // complete compaction phase than we've tried so far might be
1637   // appropriate.
1638   assert(*succeeded, "sanity");
1639   return NULL;
1640 }
1641 
1642 // Attempting to expand the heap sufficiently
1643 // to support an allocation of the given "word_size".  If
1644 // successful, perform the allocation and return the address of the
1645 // allocated block, or else "NULL".
1646 
1647 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1648   assert_at_safepoint(true /* should_be_vm_thread */);
1649 
1650   _verifier->verify_region_sets_optional();
1651 
1652   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1653   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1654                             word_size * HeapWordSize);
1655 
1656 
1657   if (expand(expand_bytes)) {
1658     _hrm.verify_optional();
1659     _verifier->verify_region_sets_optional();
1660     return attempt_allocation_at_safepoint(word_size,
1661                                            context,
1662                                            false /* expect_null_mutator_alloc_region */);
1663   }
1664   return NULL;
1665 }
1666 
1667 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1668   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1669   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1670                                        HeapRegion::GrainBytes);
1671 
1672   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1673                             expand_bytes, aligned_expand_bytes);
1674 
1675   if (is_maximal_no_gc()) {
1676     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1677     return false;
1678   }
1679 
1680   double expand_heap_start_time_sec = os::elapsedTime();
1681   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1682   assert(regions_to_expand > 0, "Must expand by at least one region");
1683 
1684   uint expanded_by = _hrm.expand_by(regions_to_expand);
1685   if (expand_time_ms != NULL) {
1686     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1687   }
1688 
1689   if (expanded_by > 0) {
1690     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1691     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1692     g1_policy()->record_new_heap_size(num_regions());
1693   } else {
1694     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1695 
1696     // The expansion of the virtual storage space was unsuccessful.
1697     // Let's see if it was because we ran out of swap.
1698     if (G1ExitOnExpansionFailure &&
1699         _hrm.available() >= regions_to_expand) {
1700       // We had head room...
1701       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1702     }
1703   }
1704   return regions_to_expand > 0;
1705 }
1706 
1707 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1708   size_t aligned_shrink_bytes =
1709     ReservedSpace::page_align_size_down(shrink_bytes);
1710   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1711                                          HeapRegion::GrainBytes);
1712   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1713 
1714   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1715   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1716 
1717 
1718   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",
1719                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1720   if (num_regions_removed > 0) {
1721     g1_policy()->record_new_heap_size(num_regions());
1722   } else {
1723     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1724   }
1725 }
1726 
1727 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1728   _verifier->verify_region_sets_optional();
1729 
1730   // We should only reach here at the end of a Full GC which means we
1731   // should not not be holding to any GC alloc regions. The method
1732   // below will make sure of that and do any remaining clean up.
1733   _allocator->abandon_gc_alloc_regions();
1734 
1735   // Instead of tearing down / rebuilding the free lists here, we
1736   // could instead use the remove_all_pending() method on free_list to
1737   // remove only the ones that we need to remove.
1738   tear_down_region_sets(true /* free_list_only */);
1739   shrink_helper(shrink_bytes);
1740   rebuild_region_sets(true /* free_list_only */);
1741 
1742   _hrm.verify_optional();
1743   _verifier->verify_region_sets_optional();
1744 }
1745 
1746 // Public methods.
1747 
1748 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1749   CollectedHeap(),
1750   _collector_policy(collector_policy),
1751   _g1_policy(create_g1_policy()),
1752   _collection_set(this, _g1_policy),
1753   _dirty_card_queue_set(false),
1754   _is_alive_closure_cm(this),
1755   _is_alive_closure_stw(this),
1756   _ref_processor_cm(NULL),
1757   _ref_processor_stw(NULL),
1758   _bot(NULL),
1759   _cg1r(NULL),
1760   _g1mm(NULL),
1761   _refine_cte_cl(NULL),
1762   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1763   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1764   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1765   _humongous_reclaim_candidates(),
1766   _has_humongous_reclaim_candidates(false),
1767   _archive_allocator(NULL),
1768   _free_regions_coming(false),
1769   _young_list(new YoungList(this)),
1770   _gc_time_stamp(0),
1771   _summary_bytes_used(0),
1772   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1773   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1774   _expand_heap_after_alloc_failure(true),
1775   _old_marking_cycles_started(0),
1776   _old_marking_cycles_completed(0),
1777   _in_cset_fast_test(),
1778   _dirty_cards_region_list(NULL),
1779   _worker_cset_start_region(NULL),
1780   _worker_cset_start_region_time_stamp(NULL),
1781   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1782   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1783 
1784   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1785                           /* are_GC_task_threads */true,
1786                           /* are_ConcurrentGC_threads */false);
1787   _workers->initialize_workers();
1788   _verifier = new G1HeapVerifier(this);
1789 
1790   _allocator = G1Allocator::create_allocator(this);
1791 
1792   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1793 
1794   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1795 
1796   // Override the default _filler_array_max_size so that no humongous filler
1797   // objects are created.
1798   _filler_array_max_size = _humongous_object_threshold_in_words;
1799 
1800   uint n_queues = ParallelGCThreads;
1801   _task_queues = new RefToScanQueueSet(n_queues);
1802 
1803   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1804   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1805   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1806 
1807   for (uint i = 0; i < n_queues; i++) {
1808     RefToScanQueue* q = new RefToScanQueue();
1809     q->initialize();
1810     _task_queues->register_queue(i, q);
1811     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1812   }
1813   clear_cset_start_regions();
1814 
1815   // Initialize the G1EvacuationFailureALot counters and flags.
1816   NOT_PRODUCT(reset_evacuation_should_fail();)
1817 
1818   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1819 }
1820 
1821 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1822                                                                  size_t size,
1823                                                                  size_t translation_factor) {
1824   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1825   // Allocate a new reserved space, preferring to use large pages.
1826   ReservedSpace rs(size, preferred_page_size);
1827   G1RegionToSpaceMapper* result  =
1828     G1RegionToSpaceMapper::create_mapper(rs,
1829                                          size,
1830                                          rs.alignment(),
1831                                          HeapRegion::GrainBytes,
1832                                          translation_factor,
1833                                          mtGC);
1834 
1835   os::trace_page_sizes_for_requested_size(description,
1836                                           size,
1837                                           preferred_page_size,
1838                                           rs.alignment(),
1839                                           rs.base(),
1840                                           rs.size());
1841 
1842   return result;
1843 }
1844 
1845 jint G1CollectedHeap::initialize() {
1846   CollectedHeap::pre_initialize();
1847   os::enable_vtime();
1848 
1849   // Necessary to satisfy locking discipline assertions.
1850 
1851   MutexLocker x(Heap_lock);
1852 
1853   // While there are no constraints in the GC code that HeapWordSize
1854   // be any particular value, there are multiple other areas in the
1855   // system which believe this to be true (e.g. oop->object_size in some
1856   // cases incorrectly returns the size in wordSize units rather than
1857   // HeapWordSize).
1858   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1859 
1860   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1861   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1862   size_t heap_alignment = collector_policy()->heap_alignment();
1863 
1864   // Ensure that the sizes are properly aligned.
1865   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1866   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1867   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1868 
1869   _refine_cte_cl = new RefineCardTableEntryClosure();
1870 
1871   jint ecode = JNI_OK;
1872   _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1873   if (_cg1r == NULL) {
1874     return ecode;
1875   }
1876 
1877   // Reserve the maximum.
1878 
1879   // When compressed oops are enabled, the preferred heap base
1880   // is calculated by subtracting the requested size from the
1881   // 32Gb boundary and using the result as the base address for
1882   // heap reservation. If the requested size is not aligned to
1883   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1884   // into the ReservedHeapSpace constructor) then the actual
1885   // base of the reserved heap may end up differing from the
1886   // address that was requested (i.e. the preferred heap base).
1887   // If this happens then we could end up using a non-optimal
1888   // compressed oops mode.
1889 
1890   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1891                                                  heap_alignment);
1892 
1893   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1894 
1895   // Create the barrier set for the entire reserved region.
1896   G1SATBCardTableLoggingModRefBS* bs
1897     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1898   bs->initialize();
1899   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1900   set_barrier_set(bs);
1901 
1902   // Also create a G1 rem set.
1903   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1904 
1905   // Carve out the G1 part of the heap.
1906   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1907   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1908   G1RegionToSpaceMapper* heap_storage =
1909     G1RegionToSpaceMapper::create_mapper(g1_rs,
1910                                          g1_rs.size(),
1911                                          page_size,
1912                                          HeapRegion::GrainBytes,
1913                                          1,
1914                                          mtJavaHeap);
1915   os::trace_page_sizes("Heap",
1916                        collector_policy()->min_heap_byte_size(),
1917                        max_byte_size,
1918                        page_size,
1919                        heap_rs.base(),
1920                        heap_rs.size());
1921   heap_storage->set_mapping_changed_listener(&_listener);
1922 
1923   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1924   G1RegionToSpaceMapper* bot_storage =
1925     create_aux_memory_mapper("Block Offset Table",
1926                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1927                              G1BlockOffsetTable::heap_map_factor());
1928 
1929   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1930   G1RegionToSpaceMapper* cardtable_storage =
1931     create_aux_memory_mapper("Card Table",
1932                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1933                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1934 
1935   G1RegionToSpaceMapper* card_counts_storage =
1936     create_aux_memory_mapper("Card Counts Table",
1937                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1938                              G1CardCounts::heap_map_factor());
1939 
1940   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1941   G1RegionToSpaceMapper* prev_bitmap_storage =
1942     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1943   G1RegionToSpaceMapper* next_bitmap_storage =
1944     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1945 
1946   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1947   g1_barrier_set()->initialize(cardtable_storage);
1948    // Do later initialization work for concurrent refinement.
1949   _cg1r->init(card_counts_storage);
1950 
1951   // 6843694 - ensure that the maximum region index can fit
1952   // in the remembered set structures.
1953   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1954   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1955 
1956   g1_rem_set()->initialize(max_capacity(), max_regions());
1957 
1958   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1959   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1960   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1961             "too many cards per region");
1962 
1963   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1964 
1965   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1966 
1967   {
1968     HeapWord* start = _hrm.reserved().start();
1969     HeapWord* end = _hrm.reserved().end();
1970     size_t granularity = HeapRegion::GrainBytes;
1971 
1972     _in_cset_fast_test.initialize(start, end, granularity);
1973     _humongous_reclaim_candidates.initialize(start, end, granularity);
1974   }
1975 
1976   // Create the G1ConcurrentMark data structure and thread.
1977   // (Must do this late, so that "max_regions" is defined.)
1978   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1979   if (_cm == NULL || !_cm->completed_initialization()) {
1980     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1981     return JNI_ENOMEM;
1982   }
1983   _cmThread = _cm->cmThread();
1984 
1985   // Now expand into the initial heap size.
1986   if (!expand(init_byte_size)) {
1987     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1988     return JNI_ENOMEM;
1989   }
1990 
1991   // Perform any initialization actions delegated to the policy.
1992   g1_policy()->init(this, &_collection_set);
1993 
1994   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1995                                                SATB_Q_FL_lock,
1996                                                G1SATBProcessCompletedThreshold,
1997                                                Shared_SATB_Q_lock);
1998 
1999   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2000                                                 DirtyCardQ_CBL_mon,
2001                                                 DirtyCardQ_FL_lock,
2002                                                 (int)concurrent_g1_refine()->yellow_zone(),
2003                                                 (int)concurrent_g1_refine()->red_zone(),
2004                                                 Shared_DirtyCardQ_lock,
2005                                                 NULL,  // fl_owner
2006                                                 true); // init_free_ids
2007 
2008   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2009                                     DirtyCardQ_CBL_mon,
2010                                     DirtyCardQ_FL_lock,
2011                                     -1, // never trigger processing
2012                                     -1, // no limit on length
2013                                     Shared_DirtyCardQ_lock,
2014                                     &JavaThread::dirty_card_queue_set());
2015 
2016   // Here we allocate the dummy HeapRegion that is required by the
2017   // G1AllocRegion class.
2018   HeapRegion* dummy_region = _hrm.get_dummy_region();
2019 
2020   // We'll re-use the same region whether the alloc region will
2021   // require BOT updates or not and, if it doesn't, then a non-young
2022   // region will complain that it cannot support allocations without
2023   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2024   dummy_region->set_eden();
2025   // Make sure it's full.
2026   dummy_region->set_top(dummy_region->end());
2027   G1AllocRegion::setup(this, dummy_region);
2028 
2029   _allocator->init_mutator_alloc_region();
2030 
2031   // Do create of the monitoring and management support so that
2032   // values in the heap have been properly initialized.
2033   _g1mm = new G1MonitoringSupport(this);
2034 
2035   G1StringDedup::initialize();
2036 
2037   _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2038   for (uint i = 0; i < ParallelGCThreads; i++) {
2039     new (&_preserved_objs[i]) OopAndMarkOopStack();
2040   }
2041 
2042   return JNI_OK;
2043 }
2044 
2045 void G1CollectedHeap::stop() {
2046   // Stop all concurrent threads. We do this to make sure these threads
2047   // do not continue to execute and access resources (e.g. logging)
2048   // that are destroyed during shutdown.
2049   _cg1r->stop();
2050   _cmThread->stop();
2051   if (G1StringDedup::is_enabled()) {
2052     G1StringDedup::stop();
2053   }
2054 }
2055 
2056 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2057   return HeapRegion::max_region_size();
2058 }
2059 
2060 void G1CollectedHeap::post_initialize() {
2061   ref_processing_init();
2062 }
2063 
2064 void G1CollectedHeap::ref_processing_init() {
2065   // Reference processing in G1 currently works as follows:
2066   //
2067   // * There are two reference processor instances. One is
2068   //   used to record and process discovered references
2069   //   during concurrent marking; the other is used to
2070   //   record and process references during STW pauses
2071   //   (both full and incremental).
2072   // * Both ref processors need to 'span' the entire heap as
2073   //   the regions in the collection set may be dotted around.
2074   //
2075   // * For the concurrent marking ref processor:
2076   //   * Reference discovery is enabled at initial marking.
2077   //   * Reference discovery is disabled and the discovered
2078   //     references processed etc during remarking.
2079   //   * Reference discovery is MT (see below).
2080   //   * Reference discovery requires a barrier (see below).
2081   //   * Reference processing may or may not be MT
2082   //     (depending on the value of ParallelRefProcEnabled
2083   //     and ParallelGCThreads).
2084   //   * A full GC disables reference discovery by the CM
2085   //     ref processor and abandons any entries on it's
2086   //     discovered lists.
2087   //
2088   // * For the STW processor:
2089   //   * Non MT discovery is enabled at the start of a full GC.
2090   //   * Processing and enqueueing during a full GC is non-MT.
2091   //   * During a full GC, references are processed after marking.
2092   //
2093   //   * Discovery (may or may not be MT) is enabled at the start
2094   //     of an incremental evacuation pause.
2095   //   * References are processed near the end of a STW evacuation pause.
2096   //   * For both types of GC:
2097   //     * Discovery is atomic - i.e. not concurrent.
2098   //     * Reference discovery will not need a barrier.
2099 
2100   MemRegion mr = reserved_region();
2101 
2102   // Concurrent Mark ref processor
2103   _ref_processor_cm =
2104     new ReferenceProcessor(mr,    // span
2105                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2106                                 // mt processing
2107                            ParallelGCThreads,
2108                                 // degree of mt processing
2109                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2110                                 // mt discovery
2111                            MAX2(ParallelGCThreads, ConcGCThreads),
2112                                 // degree of mt discovery
2113                            false,
2114                                 // Reference discovery is not atomic
2115                            &_is_alive_closure_cm);
2116                                 // is alive closure
2117                                 // (for efficiency/performance)
2118 
2119   // STW ref processor
2120   _ref_processor_stw =
2121     new ReferenceProcessor(mr,    // span
2122                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2123                                 // mt processing
2124                            ParallelGCThreads,
2125                                 // degree of mt processing
2126                            (ParallelGCThreads > 1),
2127                                 // mt discovery
2128                            ParallelGCThreads,
2129                                 // degree of mt discovery
2130                            true,
2131                                 // Reference discovery is atomic
2132                            &_is_alive_closure_stw);
2133                                 // is alive closure
2134                                 // (for efficiency/performance)
2135 }
2136 
2137 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2138   return _collector_policy;
2139 }
2140 
2141 size_t G1CollectedHeap::capacity() const {
2142   return _hrm.length() * HeapRegion::GrainBytes;
2143 }
2144 
2145 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2146   hr->reset_gc_time_stamp();
2147 }
2148 
2149 #ifndef PRODUCT
2150 
2151 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2152 private:
2153   unsigned _gc_time_stamp;
2154   bool _failures;
2155 
2156 public:
2157   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2158     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2159 
2160   virtual bool doHeapRegion(HeapRegion* hr) {
2161     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2162     if (_gc_time_stamp != region_gc_time_stamp) {
2163       log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2164                             region_gc_time_stamp, _gc_time_stamp);
2165       _failures = true;
2166     }
2167     return false;
2168   }
2169 
2170   bool failures() { return _failures; }
2171 };
2172 
2173 void G1CollectedHeap::check_gc_time_stamps() {
2174   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2175   heap_region_iterate(&cl);
2176   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2177 }
2178 #endif // PRODUCT
2179 
2180 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2181   _cg1r->hot_card_cache()->drain(cl, worker_i);
2182 }
2183 
2184 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2185   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2186   size_t n_completed_buffers = 0;
2187   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2188     n_completed_buffers++;
2189   }
2190   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2191   dcqs.clear_n_completed_buffers();
2192   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2193 }
2194 
2195 // Computes the sum of the storage used by the various regions.
2196 size_t G1CollectedHeap::used() const {
2197   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2198   if (_archive_allocator != NULL) {
2199     result += _archive_allocator->used();
2200   }
2201   return result;
2202 }
2203 
2204 size_t G1CollectedHeap::used_unlocked() const {
2205   return _summary_bytes_used;
2206 }
2207 
2208 class SumUsedClosure: public HeapRegionClosure {
2209   size_t _used;
2210 public:
2211   SumUsedClosure() : _used(0) {}
2212   bool doHeapRegion(HeapRegion* r) {
2213     _used += r->used();
2214     return false;
2215   }
2216   size_t result() { return _used; }
2217 };
2218 
2219 size_t G1CollectedHeap::recalculate_used() const {
2220   double recalculate_used_start = os::elapsedTime();
2221 
2222   SumUsedClosure blk;
2223   heap_region_iterate(&blk);
2224 
2225   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2226   return blk.result();
2227 }
2228 
2229 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2230   switch (cause) {
2231     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2232     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2233     case GCCause::_update_allocation_context_stats_inc: return true;
2234     case GCCause::_wb_conc_mark:                        return true;
2235     default :                                           return false;
2236   }
2237 }
2238 
2239 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2240   switch (cause) {
2241     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2242     case GCCause::_g1_humongous_allocation: return true;
2243     default:                                return is_user_requested_concurrent_full_gc(cause);
2244   }
2245 }
2246 
2247 #ifndef PRODUCT
2248 void G1CollectedHeap::allocate_dummy_regions() {
2249   // Let's fill up most of the region
2250   size_t word_size = HeapRegion::GrainWords - 1024;
2251   // And as a result the region we'll allocate will be humongous.
2252   guarantee(is_humongous(word_size), "sanity");
2253 
2254   // _filler_array_max_size is set to humongous object threshold
2255   // but temporarily change it to use CollectedHeap::fill_with_object().
2256   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2257 
2258   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2259     // Let's use the existing mechanism for the allocation
2260     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2261                                                  AllocationContext::system());
2262     if (dummy_obj != NULL) {
2263       MemRegion mr(dummy_obj, word_size);
2264       CollectedHeap::fill_with_object(mr);
2265     } else {
2266       // If we can't allocate once, we probably cannot allocate
2267       // again. Let's get out of the loop.
2268       break;
2269     }
2270   }
2271 }
2272 #endif // !PRODUCT
2273 
2274 void G1CollectedHeap::increment_old_marking_cycles_started() {
2275   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2276          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2277          "Wrong marking cycle count (started: %d, completed: %d)",
2278          _old_marking_cycles_started, _old_marking_cycles_completed);
2279 
2280   _old_marking_cycles_started++;
2281 }
2282 
2283 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2284   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2285 
2286   // We assume that if concurrent == true, then the caller is a
2287   // concurrent thread that was joined the Suspendible Thread
2288   // Set. If there's ever a cheap way to check this, we should add an
2289   // assert here.
2290 
2291   // Given that this method is called at the end of a Full GC or of a
2292   // concurrent cycle, and those can be nested (i.e., a Full GC can
2293   // interrupt a concurrent cycle), the number of full collections
2294   // completed should be either one (in the case where there was no
2295   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2296   // behind the number of full collections started.
2297 
2298   // This is the case for the inner caller, i.e. a Full GC.
2299   assert(concurrent ||
2300          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2301          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2302          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2303          "is inconsistent with _old_marking_cycles_completed = %u",
2304          _old_marking_cycles_started, _old_marking_cycles_completed);
2305 
2306   // This is the case for the outer caller, i.e. the concurrent cycle.
2307   assert(!concurrent ||
2308          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2309          "for outer caller (concurrent cycle): "
2310          "_old_marking_cycles_started = %u "
2311          "is inconsistent with _old_marking_cycles_completed = %u",
2312          _old_marking_cycles_started, _old_marking_cycles_completed);
2313 
2314   _old_marking_cycles_completed += 1;
2315 
2316   // We need to clear the "in_progress" flag in the CM thread before
2317   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2318   // is set) so that if a waiter requests another System.gc() it doesn't
2319   // incorrectly see that a marking cycle is still in progress.
2320   if (concurrent) {
2321     _cmThread->set_idle();
2322   }
2323 
2324   // This notify_all() will ensure that a thread that called
2325   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2326   // and it's waiting for a full GC to finish will be woken up. It is
2327   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2328   FullGCCount_lock->notify_all();
2329 }
2330 
2331 void G1CollectedHeap::collect(GCCause::Cause cause) {
2332   assert_heap_not_locked();
2333 
2334   uint gc_count_before;
2335   uint old_marking_count_before;
2336   uint full_gc_count_before;
2337   bool retry_gc;
2338 
2339   do {
2340     retry_gc = false;
2341 
2342     {
2343       MutexLocker ml(Heap_lock);
2344 
2345       // Read the GC count while holding the Heap_lock
2346       gc_count_before = total_collections();
2347       full_gc_count_before = total_full_collections();
2348       old_marking_count_before = _old_marking_cycles_started;
2349     }
2350 
2351     if (should_do_concurrent_full_gc(cause)) {
2352       // Schedule an initial-mark evacuation pause that will start a
2353       // concurrent cycle. We're setting word_size to 0 which means that
2354       // we are not requesting a post-GC allocation.
2355       VM_G1IncCollectionPause op(gc_count_before,
2356                                  0,     /* word_size */
2357                                  true,  /* should_initiate_conc_mark */
2358                                  g1_policy()->max_pause_time_ms(),
2359                                  cause);
2360       op.set_allocation_context(AllocationContext::current());
2361 
2362       VMThread::execute(&op);
2363       if (!op.pause_succeeded()) {
2364         if (old_marking_count_before == _old_marking_cycles_started) {
2365           retry_gc = op.should_retry_gc();
2366         } else {
2367           // A Full GC happened while we were trying to schedule the
2368           // initial-mark GC. No point in starting a new cycle given
2369           // that the whole heap was collected anyway.
2370         }
2371 
2372         if (retry_gc) {
2373           if (GCLocker::is_active_and_needs_gc()) {
2374             GCLocker::stall_until_clear();
2375           }
2376         }
2377       }
2378     } else {
2379       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2380           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2381 
2382         // Schedule a standard evacuation pause. We're setting word_size
2383         // to 0 which means that we are not requesting a post-GC allocation.
2384         VM_G1IncCollectionPause op(gc_count_before,
2385                                    0,     /* word_size */
2386                                    false, /* should_initiate_conc_mark */
2387                                    g1_policy()->max_pause_time_ms(),
2388                                    cause);
2389         VMThread::execute(&op);
2390       } else {
2391         // Schedule a Full GC.
2392         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2393         VMThread::execute(&op);
2394       }
2395     }
2396   } while (retry_gc);
2397 }
2398 
2399 bool G1CollectedHeap::is_in(const void* p) const {
2400   if (_hrm.reserved().contains(p)) {
2401     // Given that we know that p is in the reserved space,
2402     // heap_region_containing() should successfully
2403     // return the containing region.
2404     HeapRegion* hr = heap_region_containing(p);
2405     return hr->is_in(p);
2406   } else {
2407     return false;
2408   }
2409 }
2410 
2411 #ifdef ASSERT
2412 bool G1CollectedHeap::is_in_exact(const void* p) const {
2413   bool contains = reserved_region().contains(p);
2414   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2415   if (contains && available) {
2416     return true;
2417   } else {
2418     return false;
2419   }
2420 }
2421 #endif
2422 
2423 bool G1CollectedHeap::obj_in_cs(oop obj) {
2424   HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2425   return r != NULL && r->in_collection_set();
2426 }
2427 
2428 // Iteration functions.
2429 
2430 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2431 
2432 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2433   ExtendedOopClosure* _cl;
2434 public:
2435   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2436   bool doHeapRegion(HeapRegion* r) {
2437     if (!r->is_continues_humongous()) {
2438       r->oop_iterate(_cl);
2439     }
2440     return false;
2441   }
2442 };
2443 
2444 // Iterates an ObjectClosure over all objects within a HeapRegion.
2445 
2446 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2447   ObjectClosure* _cl;
2448 public:
2449   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2450   bool doHeapRegion(HeapRegion* r) {
2451     if (!r->is_continues_humongous()) {
2452       r->object_iterate(_cl);
2453     }
2454     return false;
2455   }
2456 };
2457 
2458 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2459   IterateObjectClosureRegionClosure blk(cl);
2460   heap_region_iterate(&blk);
2461 }
2462 
2463 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2464   _hrm.iterate(cl);
2465 }
2466 
2467 void
2468 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2469                                          uint worker_id,
2470                                          HeapRegionClaimer *hrclaimer,
2471                                          bool concurrent) const {
2472   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2473 }
2474 
2475 // Clear the cached CSet starting regions and (more importantly)
2476 // the time stamps. Called when we reset the GC time stamp.
2477 void G1CollectedHeap::clear_cset_start_regions() {
2478   assert(_worker_cset_start_region != NULL, "sanity");
2479   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2480 
2481   for (uint i = 0; i < ParallelGCThreads; i++) {
2482     _worker_cset_start_region[i] = NULL;
2483     _worker_cset_start_region_time_stamp[i] = 0;
2484   }
2485 }
2486 
2487 // Given the id of a worker, obtain or calculate a suitable
2488 // starting region for iterating over the current collection set.
2489 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2490   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2491 
2492   HeapRegion* result = NULL;
2493   unsigned gc_time_stamp = get_gc_time_stamp();
2494 
2495   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2496     // Cached starting region for current worker was set
2497     // during the current pause - so it's valid.
2498     // Note: the cached starting heap region may be NULL
2499     // (when the collection set is empty).
2500     result = _worker_cset_start_region[worker_i];
2501     assert(result == NULL || result->in_collection_set(), "sanity");
2502     return result;
2503   }
2504 
2505   // The cached entry was not valid so let's calculate
2506   // a suitable starting heap region for this worker.
2507 
2508   // We want the parallel threads to start their collection
2509   // set iteration at different collection set regions to
2510   // avoid contention.
2511   // If we have:
2512   //          n collection set regions
2513   //          p threads
2514   // Then thread t will start at region floor ((t * n) / p)
2515 
2516   result = collection_set()->head();
2517   uint cs_size = collection_set()->region_length();
2518   uint active_workers = workers()->active_workers();
2519 
2520   uint end_ind   = (cs_size * worker_i) / active_workers;
2521   uint start_ind = 0;
2522 
2523   if (worker_i > 0 &&
2524       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2525     // Previous workers starting region is valid
2526     // so let's iterate from there
2527     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2528     OrderAccess::loadload();
2529     result = _worker_cset_start_region[worker_i - 1];
2530   }
2531 
2532   for (uint i = start_ind; i < end_ind; i++) {
2533     result = result->next_in_collection_set();
2534   }
2535 
2536   // Note: the calculated starting heap region may be NULL
2537   // (when the collection set is empty).
2538   assert(result == NULL || result->in_collection_set(), "sanity");
2539   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2540          "should be updated only once per pause");
2541   _worker_cset_start_region[worker_i] = result;
2542   OrderAccess::storestore();
2543   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2544   return result;
2545 }
2546 
2547 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2548   HeapRegion* r = collection_set()->head();
2549   while (r != NULL) {
2550     HeapRegion* next = r->next_in_collection_set();
2551     if (cl->doHeapRegion(r)) {
2552       cl->incomplete();
2553       return;
2554     }
2555     r = next;
2556   }
2557 }
2558 
2559 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2560                                                   HeapRegionClosure *cl) {
2561   if (r == NULL) {
2562     // The CSet is empty so there's nothing to do.
2563     return;
2564   }
2565 
2566   assert(r->in_collection_set(),
2567          "Start region must be a member of the collection set.");
2568   HeapRegion* cur = r;
2569   while (cur != NULL) {
2570     HeapRegion* next = cur->next_in_collection_set();
2571     if (cl->doHeapRegion(cur) && false) {
2572       cl->incomplete();
2573       return;
2574     }
2575     cur = next;
2576   }
2577   cur = collection_set()->head();
2578   while (cur != r) {
2579     HeapRegion* next = cur->next_in_collection_set();
2580     if (cl->doHeapRegion(cur) && false) {
2581       cl->incomplete();
2582       return;
2583     }
2584     cur = next;
2585   }
2586 }
2587 
2588 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2589   HeapRegion* result = _hrm.next_region_in_heap(from);
2590   while (result != NULL && result->is_pinned()) {
2591     result = _hrm.next_region_in_heap(result);
2592   }
2593   return result;
2594 }
2595 
2596 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2597   HeapRegion* hr = heap_region_containing(addr);
2598   return hr->block_start(addr);
2599 }
2600 
2601 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2602   HeapRegion* hr = heap_region_containing(addr);
2603   return hr->block_size(addr);
2604 }
2605 
2606 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2607   HeapRegion* hr = heap_region_containing(addr);
2608   return hr->block_is_obj(addr);
2609 }
2610 
2611 bool G1CollectedHeap::supports_tlab_allocation() const {
2612   return true;
2613 }
2614 
2615 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2616   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2617 }
2618 
2619 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2620   return young_list()->eden_used_bytes();
2621 }
2622 
2623 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2624 // must be equal to the humongous object limit.
2625 size_t G1CollectedHeap::max_tlab_size() const {
2626   return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2627 }
2628 
2629 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2630   AllocationContext_t context = AllocationContext::current();
2631   return _allocator->unsafe_max_tlab_alloc(context);
2632 }
2633 
2634 size_t G1CollectedHeap::max_capacity() const {
2635   return _hrm.reserved().byte_size();
2636 }
2637 
2638 jlong G1CollectedHeap::millis_since_last_gc() {
2639   // assert(false, "NYI");
2640   return 0;
2641 }
2642 
2643 void G1CollectedHeap::prepare_for_verify() {
2644   _verifier->prepare_for_verify();
2645 }
2646 
2647 void G1CollectedHeap::verify(VerifyOption vo) {
2648   _verifier->verify(vo);
2649 }
2650 
2651 class PrintRegionClosure: public HeapRegionClosure {
2652   outputStream* _st;
2653 public:
2654   PrintRegionClosure(outputStream* st) : _st(st) {}
2655   bool doHeapRegion(HeapRegion* r) {
2656     r->print_on(_st);
2657     return false;
2658   }
2659 };
2660 
2661 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2662                                        const HeapRegion* hr,
2663                                        const VerifyOption vo) const {
2664   switch (vo) {
2665   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2666   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2667   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
2668   default:                            ShouldNotReachHere();
2669   }
2670   return false; // keep some compilers happy
2671 }
2672 
2673 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2674                                        const VerifyOption vo) const {
2675   switch (vo) {
2676   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2677   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2678   case VerifyOption_G1UseMarkWord: {
2679     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2680     return !obj->is_gc_marked() && !hr->is_archive();
2681   }
2682   default:                            ShouldNotReachHere();
2683   }
2684   return false; // keep some compilers happy
2685 }
2686 
2687 void G1CollectedHeap::print_heap_regions() const {
2688   Log(gc, heap, region) log;
2689   if (log.is_trace()) {
2690     ResourceMark rm;
2691     print_regions_on(log.trace_stream());
2692   }
2693 }
2694 
2695 void G1CollectedHeap::print_on(outputStream* st) const {
2696   st->print(" %-20s", "garbage-first heap");
2697   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2698             capacity()/K, used_unlocked()/K);
2699   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2700             p2i(_hrm.reserved().start()),
2701             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2702             p2i(_hrm.reserved().end()));
2703   st->cr();
2704   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2705   uint young_regions = _young_list->length();
2706   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2707             (size_t) young_regions * HeapRegion::GrainBytes / K);
2708   uint survivor_regions = _young_list->survivor_length();
2709   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2710             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2711   st->cr();
2712   MetaspaceAux::print_on(st);
2713 }
2714 
2715 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2716   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2717                "HS=humongous(starts), HC=humongous(continues), "
2718                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2719                "AC=allocation context, "
2720                "TAMS=top-at-mark-start (previous, next)");
2721   PrintRegionClosure blk(st);
2722   heap_region_iterate(&blk);
2723 }
2724 
2725 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2726   print_on(st);
2727 
2728   // Print the per-region information.
2729   print_regions_on(st);
2730 }
2731 
2732 void G1CollectedHeap::print_on_error(outputStream* st) const {
2733   this->CollectedHeap::print_on_error(st);
2734 
2735   if (_cm != NULL) {
2736     st->cr();
2737     _cm->print_on_error(st);
2738   }
2739 }
2740 
2741 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2742   workers()->print_worker_threads_on(st);
2743   _cmThread->print_on(st);
2744   st->cr();
2745   _cm->print_worker_threads_on(st);
2746   _cg1r->print_worker_threads_on(st); // also prints the sample thread
2747   if (G1StringDedup::is_enabled()) {
2748     G1StringDedup::print_worker_threads_on(st);
2749   }
2750 }
2751 
2752 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2753   workers()->threads_do(tc);
2754   tc->do_thread(_cmThread);
2755   _cm->threads_do(tc);
2756   _cg1r->threads_do(tc); // also iterates over the sample thread
2757   if (G1StringDedup::is_enabled()) {
2758     G1StringDedup::threads_do(tc);
2759   }
2760 }
2761 
2762 void G1CollectedHeap::print_tracing_info() const {
2763   g1_rem_set()->print_summary_info();
2764   concurrent_mark()->print_summary_info();
2765   g1_policy()->print_yg_surv_rate_info();
2766 }
2767 
2768 #ifndef PRODUCT
2769 // Helpful for debugging RSet issues.
2770 
2771 class PrintRSetsClosure : public HeapRegionClosure {
2772 private:
2773   const char* _msg;
2774   size_t _occupied_sum;
2775 
2776 public:
2777   bool doHeapRegion(HeapRegion* r) {
2778     HeapRegionRemSet* hrrs = r->rem_set();
2779     size_t occupied = hrrs->occupied();
2780     _occupied_sum += occupied;
2781 
2782     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2783     if (occupied == 0) {
2784       tty->print_cr("  RSet is empty");
2785     } else {
2786       hrrs->print();
2787     }
2788     tty->print_cr("----------");
2789     return false;
2790   }
2791 
2792   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2793     tty->cr();
2794     tty->print_cr("========================================");
2795     tty->print_cr("%s", msg);
2796     tty->cr();
2797   }
2798 
2799   ~PrintRSetsClosure() {
2800     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2801     tty->print_cr("========================================");
2802     tty->cr();
2803   }
2804 };
2805 
2806 void G1CollectedHeap::print_cset_rsets() {
2807   PrintRSetsClosure cl("Printing CSet RSets");
2808   collection_set_iterate(&cl);
2809 }
2810 
2811 void G1CollectedHeap::print_all_rsets() {
2812   PrintRSetsClosure cl("Printing All RSets");;
2813   heap_region_iterate(&cl);
2814 }
2815 #endif // PRODUCT
2816 
2817 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2818   YoungList* young_list = heap()->young_list();
2819 
2820   size_t eden_used_bytes = young_list->eden_used_bytes();
2821   size_t survivor_used_bytes = young_list->survivor_used_bytes();
2822   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2823 
2824   size_t eden_capacity_bytes =
2825     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2826 
2827   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2828   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2829                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2830 }
2831 
2832 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2833   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2834                        stats->unused(), stats->used(), stats->region_end_waste(),
2835                        stats->regions_filled(), stats->direct_allocated(),
2836                        stats->failure_used(), stats->failure_waste());
2837 }
2838 
2839 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2840   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2841   gc_tracer->report_gc_heap_summary(when, heap_summary);
2842 
2843   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2844   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2845 }
2846 
2847 G1CollectedHeap* G1CollectedHeap::heap() {
2848   CollectedHeap* heap = Universe::heap();
2849   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2850   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2851   return (G1CollectedHeap*)heap;
2852 }
2853 
2854 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2855   // always_do_update_barrier = false;
2856   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2857   // Fill TLAB's and such
2858   accumulate_statistics_all_tlabs();
2859   ensure_parsability(true);
2860 
2861   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2862 }
2863 
2864 void G1CollectedHeap::gc_epilogue(bool full) {
2865   // we are at the end of the GC. Total collections has already been increased.
2866   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2867 
2868   // FIXME: what is this about?
2869   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2870   // is set.
2871 #if defined(COMPILER2) || INCLUDE_JVMCI
2872   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2873 #endif
2874   // always_do_update_barrier = true;
2875 
2876   resize_all_tlabs();
2877   allocation_context_stats().update(full);
2878 
2879   // We have just completed a GC. Update the soft reference
2880   // policy with the new heap occupancy
2881   Universe::update_heap_info_at_gc();
2882 }
2883 
2884 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2885                                                uint gc_count_before,
2886                                                bool* succeeded,
2887                                                GCCause::Cause gc_cause) {
2888   assert_heap_not_locked_and_not_at_safepoint();
2889   VM_G1IncCollectionPause op(gc_count_before,
2890                              word_size,
2891                              false, /* should_initiate_conc_mark */
2892                              g1_policy()->max_pause_time_ms(),
2893                              gc_cause);
2894 
2895   op.set_allocation_context(AllocationContext::current());
2896   VMThread::execute(&op);
2897 
2898   HeapWord* result = op.result();
2899   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2900   assert(result == NULL || ret_succeeded,
2901          "the result should be NULL if the VM did not succeed");
2902   *succeeded = ret_succeeded;
2903 
2904   assert_heap_not_locked();
2905   return result;
2906 }
2907 
2908 void
2909 G1CollectedHeap::doConcurrentMark() {
2910   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2911   if (!_cmThread->in_progress()) {
2912     _cmThread->set_started();
2913     CGC_lock->notify();
2914   }
2915 }
2916 
2917 size_t G1CollectedHeap::pending_card_num() {
2918   size_t extra_cards = 0;
2919   JavaThread *curr = Threads::first();
2920   while (curr != NULL) {
2921     DirtyCardQueue& dcq = curr->dirty_card_queue();
2922     extra_cards += dcq.size();
2923     curr = curr->next();
2924   }
2925   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2926   size_t buffer_size = dcqs.buffer_size();
2927   size_t buffer_num = dcqs.completed_buffers_num();
2928 
2929   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2930   // in bytes - not the number of 'entries'. We need to convert
2931   // into a number of cards.
2932   return (buffer_size * buffer_num + extra_cards) / oopSize;
2933 }
2934 
2935 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2936  private:
2937   size_t _total_humongous;
2938   size_t _candidate_humongous;
2939 
2940   DirtyCardQueue _dcq;
2941 
2942   // We don't nominate objects with many remembered set entries, on
2943   // the assumption that such objects are likely still live.
2944   bool is_remset_small(HeapRegion* region) const {
2945     HeapRegionRemSet* const rset = region->rem_set();
2946     return G1EagerReclaimHumongousObjectsWithStaleRefs
2947       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2948       : rset->is_empty();
2949   }
2950 
2951   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2952     assert(region->is_starts_humongous(), "Must start a humongous object");
2953 
2954     oop obj = oop(region->bottom());
2955 
2956     // Dead objects cannot be eager reclaim candidates. Due to class
2957     // unloading it is unsafe to query their classes so we return early.
2958     if (heap->is_obj_dead(obj, region)) {
2959       return false;
2960     }
2961 
2962     // Candidate selection must satisfy the following constraints
2963     // while concurrent marking is in progress:
2964     //
2965     // * In order to maintain SATB invariants, an object must not be
2966     // reclaimed if it was allocated before the start of marking and
2967     // has not had its references scanned.  Such an object must have
2968     // its references (including type metadata) scanned to ensure no
2969     // live objects are missed by the marking process.  Objects
2970     // allocated after the start of concurrent marking don't need to
2971     // be scanned.
2972     //
2973     // * An object must not be reclaimed if it is on the concurrent
2974     // mark stack.  Objects allocated after the start of concurrent
2975     // marking are never pushed on the mark stack.
2976     //
2977     // Nominating only objects allocated after the start of concurrent
2978     // marking is sufficient to meet both constraints.  This may miss
2979     // some objects that satisfy the constraints, but the marking data
2980     // structures don't support efficiently performing the needed
2981     // additional tests or scrubbing of the mark stack.
2982     //
2983     // However, we presently only nominate is_typeArray() objects.
2984     // A humongous object containing references induces remembered
2985     // set entries on other regions.  In order to reclaim such an
2986     // object, those remembered sets would need to be cleaned up.
2987     //
2988     // We also treat is_typeArray() objects specially, allowing them
2989     // to be reclaimed even if allocated before the start of
2990     // concurrent mark.  For this we rely on mark stack insertion to
2991     // exclude is_typeArray() objects, preventing reclaiming an object
2992     // that is in the mark stack.  We also rely on the metadata for
2993     // such objects to be built-in and so ensured to be kept live.
2994     // Frequent allocation and drop of large binary blobs is an
2995     // important use case for eager reclaim, and this special handling
2996     // may reduce needed headroom.
2997 
2998     return obj->is_typeArray() && is_remset_small(region);
2999   }
3000 
3001  public:
3002   RegisterHumongousWithInCSetFastTestClosure()
3003   : _total_humongous(0),
3004     _candidate_humongous(0),
3005     _dcq(&JavaThread::dirty_card_queue_set()) {
3006   }
3007 
3008   virtual bool doHeapRegion(HeapRegion* r) {
3009     if (!r->is_starts_humongous()) {
3010       return false;
3011     }
3012     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3013 
3014     bool is_candidate = humongous_region_is_candidate(g1h, r);
3015     uint rindex = r->hrm_index();
3016     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3017     if (is_candidate) {
3018       _candidate_humongous++;
3019       g1h->register_humongous_region_with_cset(rindex);
3020       // Is_candidate already filters out humongous object with large remembered sets.
3021       // If we have a humongous object with a few remembered sets, we simply flush these
3022       // remembered set entries into the DCQS. That will result in automatic
3023       // re-evaluation of their remembered set entries during the following evacuation
3024       // phase.
3025       if (!r->rem_set()->is_empty()) {
3026         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3027                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3028         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3029         HeapRegionRemSetIterator hrrs(r->rem_set());
3030         size_t card_index;
3031         while (hrrs.has_next(card_index)) {
3032           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3033           // The remembered set might contain references to already freed
3034           // regions. Filter out such entries to avoid failing card table
3035           // verification.
3036           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3037             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3038               *card_ptr = CardTableModRefBS::dirty_card_val();
3039               _dcq.enqueue(card_ptr);
3040             }
3041           }
3042         }
3043         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3044                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3045                hrrs.n_yielded(), r->rem_set()->occupied());
3046         r->rem_set()->clear_locked();
3047       }
3048       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3049     }
3050     _total_humongous++;
3051 
3052     return false;
3053   }
3054 
3055   size_t total_humongous() const { return _total_humongous; }
3056   size_t candidate_humongous() const { return _candidate_humongous; }
3057 
3058   void flush_rem_set_entries() { _dcq.flush(); }
3059 };
3060 
3061 void G1CollectedHeap::register_humongous_regions_with_cset() {
3062   if (!G1EagerReclaimHumongousObjects) {
3063     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3064     return;
3065   }
3066   double time = os::elapsed_counter();
3067 
3068   // Collect reclaim candidate information and register candidates with cset.
3069   RegisterHumongousWithInCSetFastTestClosure cl;
3070   heap_region_iterate(&cl);
3071 
3072   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3073   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3074                                                                   cl.total_humongous(),
3075                                                                   cl.candidate_humongous());
3076   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3077 
3078   // Finally flush all remembered set entries to re-check into the global DCQS.
3079   cl.flush_rem_set_entries();
3080 }
3081 
3082 class VerifyRegionRemSetClosure : public HeapRegionClosure {
3083   public:
3084     bool doHeapRegion(HeapRegion* hr) {
3085       if (!hr->is_archive() && !hr->is_continues_humongous()) {
3086         hr->verify_rem_set();
3087       }
3088       return false;
3089     }
3090 };
3091 
3092 uint G1CollectedHeap::num_task_queues() const {
3093   return _task_queues->size();
3094 }
3095 
3096 #if TASKQUEUE_STATS
3097 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3098   st->print_raw_cr("GC Task Stats");
3099   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3100   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3101 }
3102 
3103 void G1CollectedHeap::print_taskqueue_stats() const {
3104   if (!log_is_enabled(Trace, gc, task, stats)) {
3105     return;
3106   }
3107   Log(gc, task, stats) log;
3108   ResourceMark rm;
3109   outputStream* st = log.trace_stream();
3110 
3111   print_taskqueue_stats_hdr(st);
3112 
3113   TaskQueueStats totals;
3114   const uint n = num_task_queues();
3115   for (uint i = 0; i < n; ++i) {
3116     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3117     totals += task_queue(i)->stats;
3118   }
3119   st->print_raw("tot "); totals.print(st); st->cr();
3120 
3121   DEBUG_ONLY(totals.verify());
3122 }
3123 
3124 void G1CollectedHeap::reset_taskqueue_stats() {
3125   const uint n = num_task_queues();
3126   for (uint i = 0; i < n; ++i) {
3127     task_queue(i)->stats.reset();
3128   }
3129 }
3130 #endif // TASKQUEUE_STATS
3131 
3132 void G1CollectedHeap::wait_for_root_region_scanning() {
3133   double scan_wait_start = os::elapsedTime();
3134   // We have to wait until the CM threads finish scanning the
3135   // root regions as it's the only way to ensure that all the
3136   // objects on them have been correctly scanned before we start
3137   // moving them during the GC.
3138   bool waited = _cm->root_regions()->wait_until_scan_finished();
3139   double wait_time_ms = 0.0;
3140   if (waited) {
3141     double scan_wait_end = os::elapsedTime();
3142     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3143   }
3144   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3145 }
3146 
3147 bool
3148 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3149   assert_at_safepoint(true /* should_be_vm_thread */);
3150   guarantee(!is_gc_active(), "collection is not reentrant");
3151 
3152   if (GCLocker::check_active_before_gc()) {
3153     return false;
3154   }
3155 
3156   _gc_timer_stw->register_gc_start();
3157 
3158   GCIdMark gc_id_mark;
3159   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3160 
3161   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3162   ResourceMark rm;
3163 
3164   wait_for_root_region_scanning();
3165 
3166   print_heap_before_gc();
3167   print_heap_regions();
3168   trace_heap_before_gc(_gc_tracer_stw);
3169 
3170   _verifier->verify_region_sets_optional();
3171   _verifier->verify_dirty_young_regions();
3172 
3173   // We should not be doing initial mark unless the conc mark thread is running
3174   if (!_cmThread->should_terminate()) {
3175     // This call will decide whether this pause is an initial-mark
3176     // pause. If it is, during_initial_mark_pause() will return true
3177     // for the duration of this pause.
3178     g1_policy()->decide_on_conc_mark_initiation();
3179   }
3180 
3181   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3182   assert(!collector_state()->during_initial_mark_pause() ||
3183           collector_state()->gcs_are_young(), "sanity");
3184 
3185   // We also do not allow mixed GCs during marking.
3186   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3187 
3188   // Record whether this pause is an initial mark. When the current
3189   // thread has completed its logging output and it's safe to signal
3190   // the CM thread, the flag's value in the policy has been reset.
3191   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3192 
3193   // Inner scope for scope based logging, timers, and stats collection
3194   {
3195     EvacuationInfo evacuation_info;
3196 
3197     if (collector_state()->during_initial_mark_pause()) {
3198       // We are about to start a marking cycle, so we increment the
3199       // full collection counter.
3200       increment_old_marking_cycles_started();
3201       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3202     }
3203 
3204     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3205 
3206     GCTraceCPUTime tcpu;
3207 
3208     FormatBuffer<> gc_string("Pause ");
3209     if (collector_state()->during_initial_mark_pause()) {
3210       gc_string.append("Initial Mark");
3211     } else if (collector_state()->gcs_are_young()) {
3212       gc_string.append("Young");
3213     } else {
3214       gc_string.append("Mixed");
3215     }
3216     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3217 
3218     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3219                                                                   workers()->active_workers(),
3220                                                                   Threads::number_of_non_daemon_threads());
3221     workers()->set_active_workers(active_workers);
3222 
3223     g1_policy()->note_gc_start();
3224 
3225     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3226     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3227 
3228     // If the secondary_free_list is not empty, append it to the
3229     // free_list. No need to wait for the cleanup operation to finish;
3230     // the region allocation code will check the secondary_free_list
3231     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3232     // set, skip this step so that the region allocation code has to
3233     // get entries from the secondary_free_list.
3234     if (!G1StressConcRegionFreeing) {
3235       append_secondary_free_list_if_not_empty_with_lock();
3236     }
3237 
3238     G1HeapTransition heap_transition(this);
3239     size_t heap_used_bytes_before_gc = used();
3240 
3241     assert(check_young_list_well_formed(), "young list should be well formed");
3242 
3243     // Don't dynamically change the number of GC threads this early.  A value of
3244     // 0 is used to indicate serial work.  When parallel work is done,
3245     // it will be set.
3246 
3247     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3248       IsGCActiveMark x;
3249 
3250       gc_prologue(false);
3251       increment_total_collections(false /* full gc */);
3252       increment_gc_time_stamp();
3253 
3254       if (VerifyRememberedSets) {
3255         log_info(gc, verify)("[Verifying RemSets before GC]");
3256         VerifyRegionRemSetClosure v_cl;
3257         heap_region_iterate(&v_cl);
3258       }
3259 
3260       _verifier->verify_before_gc();
3261 
3262       _verifier->check_bitmaps("GC Start");
3263 
3264 #if defined(COMPILER2) || INCLUDE_JVMCI
3265       DerivedPointerTable::clear();
3266 #endif
3267 
3268       // Please see comment in g1CollectedHeap.hpp and
3269       // G1CollectedHeap::ref_processing_init() to see how
3270       // reference processing currently works in G1.
3271 
3272       // Enable discovery in the STW reference processor
3273       if (g1_policy()->should_process_references()) {
3274         ref_processor_stw()->enable_discovery();
3275       } else {
3276         ref_processor_stw()->disable_discovery();
3277       }
3278 
3279       {
3280         // We want to temporarily turn off discovery by the
3281         // CM ref processor, if necessary, and turn it back on
3282         // on again later if we do. Using a scoped
3283         // NoRefDiscovery object will do this.
3284         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3285 
3286         // Forget the current alloc region (we might even choose it to be part
3287         // of the collection set!).
3288         _allocator->release_mutator_alloc_region();
3289 
3290         // This timing is only used by the ergonomics to handle our pause target.
3291         // It is unclear why this should not include the full pause. We will
3292         // investigate this in CR 7178365.
3293         //
3294         // Preserving the old comment here if that helps the investigation:
3295         //
3296         // The elapsed time induced by the start time below deliberately elides
3297         // the possible verification above.
3298         double sample_start_time_sec = os::elapsedTime();
3299 
3300         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3301 
3302         if (collector_state()->during_initial_mark_pause()) {
3303           concurrent_mark()->checkpointRootsInitialPre();
3304         }
3305 
3306         g1_policy()->finalize_collection_set(target_pause_time_ms);
3307 
3308         evacuation_info.set_collectionset_regions(collection_set()->region_length());
3309 
3310         // Make sure the remembered sets are up to date. This needs to be
3311         // done before register_humongous_regions_with_cset(), because the
3312         // remembered sets are used there to choose eager reclaim candidates.
3313         // If the remembered sets are not up to date we might miss some
3314         // entries that need to be handled.
3315         g1_rem_set()->cleanupHRRS();
3316 
3317         register_humongous_regions_with_cset();
3318 
3319         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3320 
3321         _cm->note_start_of_gc();
3322         // We call this after finalize_cset() to
3323         // ensure that the CSet has been finalized.
3324         _cm->verify_no_cset_oops();
3325 
3326         if (_hr_printer.is_active()) {
3327           HeapRegion* hr = collection_set()->head();
3328           while (hr != NULL) {
3329             _hr_printer.cset(hr);
3330             hr = hr->next_in_collection_set();
3331           }
3332         }
3333 
3334         // Initialize the GC alloc regions.
3335         _allocator->init_gc_alloc_regions(evacuation_info);
3336 
3337         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3338         pre_evacuate_collection_set();
3339 
3340         // Actually do the work...
3341         evacuate_collection_set(evacuation_info, &per_thread_states);
3342 
3343         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3344 
3345         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3346         free_collection_set(collection_set()->head(), evacuation_info, surviving_young_words);
3347 
3348         eagerly_reclaim_humongous_regions();
3349 
3350         collection_set()->clear_head();
3351 
3352         record_obj_copy_mem_stats();
3353         _survivor_evac_stats.adjust_desired_plab_sz();
3354         _old_evac_stats.adjust_desired_plab_sz();
3355 
3356         // Start a new incremental collection set for the next pause.
3357         collection_set()->start_incremental_building();
3358 
3359         clear_cset_fast_test();
3360 
3361         // Don't check the whole heap at this point as the
3362         // GC alloc regions from this pause have been tagged
3363         // as survivors and moved on to the survivor list.
3364         // Survivor regions will fail the !is_young() check.
3365         assert(check_young_list_empty(false /* check_heap */),
3366           "young list should be empty");
3367 
3368         _young_list->reset_auxilary_lists();
3369 
3370         if (evacuation_failed()) {
3371           set_used(recalculate_used());
3372           if (_archive_allocator != NULL) {
3373             _archive_allocator->clear_used();
3374           }
3375           for (uint i = 0; i < ParallelGCThreads; i++) {
3376             if (_evacuation_failed_info_array[i].has_failed()) {
3377               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3378             }
3379           }
3380         } else {
3381           // The "used" of the the collection set have already been subtracted
3382           // when they were freed.  Add in the bytes evacuated.
3383           increase_used(g1_policy()->bytes_copied_during_gc());
3384         }
3385 
3386         if (collector_state()->during_initial_mark_pause()) {
3387           // We have to do this before we notify the CM threads that
3388           // they can start working to make sure that all the
3389           // appropriate initialization is done on the CM object.
3390           concurrent_mark()->checkpointRootsInitialPost();
3391           collector_state()->set_mark_in_progress(true);
3392           // Note that we don't actually trigger the CM thread at
3393           // this point. We do that later when we're sure that
3394           // the current thread has completed its logging output.
3395         }
3396 
3397         allocate_dummy_regions();
3398 
3399         _allocator->init_mutator_alloc_region();
3400 
3401         {
3402           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3403           if (expand_bytes > 0) {
3404             size_t bytes_before = capacity();
3405             // No need for an ergo logging here,
3406             // expansion_amount() does this when it returns a value > 0.
3407             double expand_ms;
3408             if (!expand(expand_bytes, &expand_ms)) {
3409               // We failed to expand the heap. Cannot do anything about it.
3410             }
3411             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3412           }
3413         }
3414 
3415         // We redo the verification but now wrt to the new CSet which
3416         // has just got initialized after the previous CSet was freed.
3417         _cm->verify_no_cset_oops();
3418         _cm->note_end_of_gc();
3419 
3420         // This timing is only used by the ergonomics to handle our pause target.
3421         // It is unclear why this should not include the full pause. We will
3422         // investigate this in CR 7178365.
3423         double sample_end_time_sec = os::elapsedTime();
3424         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3425         size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3426         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3427 
3428         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3429         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3430 
3431         MemoryService::track_memory_usage();
3432 
3433         // In prepare_for_verify() below we'll need to scan the deferred
3434         // update buffers to bring the RSets up-to-date if
3435         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3436         // the update buffers we'll probably need to scan cards on the
3437         // regions we just allocated to (i.e., the GC alloc
3438         // regions). However, during the last GC we called
3439         // set_saved_mark() on all the GC alloc regions, so card
3440         // scanning might skip the [saved_mark_word()...top()] area of
3441         // those regions (i.e., the area we allocated objects into
3442         // during the last GC). But it shouldn't. Given that
3443         // saved_mark_word() is conditional on whether the GC time stamp
3444         // on the region is current or not, by incrementing the GC time
3445         // stamp here we invalidate all the GC time stamps on all the
3446         // regions and saved_mark_word() will simply return top() for
3447         // all the regions. This is a nicer way of ensuring this rather
3448         // than iterating over the regions and fixing them. In fact, the
3449         // GC time stamp increment here also ensures that
3450         // saved_mark_word() will return top() between pauses, i.e.,
3451         // during concurrent refinement. So we don't need the
3452         // is_gc_active() check to decided which top to use when
3453         // scanning cards (see CR 7039627).
3454         increment_gc_time_stamp();
3455 
3456         if (VerifyRememberedSets) {
3457           log_info(gc, verify)("[Verifying RemSets after GC]");
3458           VerifyRegionRemSetClosure v_cl;
3459           heap_region_iterate(&v_cl);
3460         }
3461 
3462         _verifier->verify_after_gc();
3463         _verifier->check_bitmaps("GC End");
3464 
3465         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3466         ref_processor_stw()->verify_no_references_recorded();
3467 
3468         // CM reference discovery will be re-enabled if necessary.
3469       }
3470 
3471 #ifdef TRACESPINNING
3472       ParallelTaskTerminator::print_termination_counts();
3473 #endif
3474 
3475       gc_epilogue(false);
3476     }
3477 
3478     // Print the remainder of the GC log output.
3479     if (evacuation_failed()) {
3480       log_info(gc)("To-space exhausted");
3481     }
3482 
3483     g1_policy()->print_phases();
3484     heap_transition.print();
3485 
3486     // It is not yet to safe to tell the concurrent mark to
3487     // start as we have some optional output below. We don't want the
3488     // output from the concurrent mark thread interfering with this
3489     // logging output either.
3490 
3491     _hrm.verify_optional();
3492     _verifier->verify_region_sets_optional();
3493 
3494     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3495     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3496 
3497     print_heap_after_gc();
3498     print_heap_regions();
3499     trace_heap_after_gc(_gc_tracer_stw);
3500 
3501     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3502     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3503     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3504     // before any GC notifications are raised.
3505     g1mm()->update_sizes();
3506 
3507     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3508     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3509     _gc_timer_stw->register_gc_end();
3510     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3511   }
3512   // It should now be safe to tell the concurrent mark thread to start
3513   // without its logging output interfering with the logging output
3514   // that came from the pause.
3515 
3516   if (should_start_conc_mark) {
3517     // CAUTION: after the doConcurrentMark() call below,
3518     // the concurrent marking thread(s) could be running
3519     // concurrently with us. Make sure that anything after
3520     // this point does not assume that we are the only GC thread
3521     // running. Note: of course, the actual marking work will
3522     // not start until the safepoint itself is released in
3523     // SuspendibleThreadSet::desynchronize().
3524     doConcurrentMark();
3525   }
3526 
3527   return true;
3528 }
3529 
3530 void G1CollectedHeap::restore_preserved_marks() {
3531   G1RestorePreservedMarksTask rpm_task(_preserved_objs);
3532   workers()->run_task(&rpm_task);
3533 }
3534 
3535 void G1CollectedHeap::remove_self_forwarding_pointers() {
3536   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3537   workers()->run_task(&rsfp_task);
3538 }
3539 
3540 void G1CollectedHeap::restore_after_evac_failure() {
3541   double remove_self_forwards_start = os::elapsedTime();
3542 
3543   remove_self_forwarding_pointers();
3544   restore_preserved_marks();
3545 
3546   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3547 }
3548 
3549 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3550   if (!_evacuation_failed) {
3551     _evacuation_failed = true;
3552   }
3553 
3554   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3555 
3556   // We want to call the "for_promotion_failure" version only in the
3557   // case of a promotion failure.
3558   if (m->must_be_preserved_for_promotion_failure(obj)) {
3559     OopAndMarkOop elem(obj, m);
3560     _preserved_objs[worker_id].push(elem);
3561   }
3562 }
3563 
3564 bool G1ParEvacuateFollowersClosure::offer_termination() {
3565   G1ParScanThreadState* const pss = par_scan_state();
3566   start_term_time();
3567   const bool res = terminator()->offer_termination();
3568   end_term_time();
3569   return res;
3570 }
3571 
3572 void G1ParEvacuateFollowersClosure::do_void() {
3573   G1ParScanThreadState* const pss = par_scan_state();
3574   pss->trim_queue();
3575   do {
3576     pss->steal_and_trim_queue(queues());
3577   } while (!offer_termination());
3578 }
3579 
3580 class G1ParTask : public AbstractGangTask {
3581 protected:
3582   G1CollectedHeap*         _g1h;
3583   G1ParScanThreadStateSet* _pss;
3584   RefToScanQueueSet*       _queues;
3585   G1RootProcessor*         _root_processor;
3586   ParallelTaskTerminator   _terminator;
3587   uint                     _n_workers;
3588 
3589 public:
3590   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3591     : AbstractGangTask("G1 collection"),
3592       _g1h(g1h),
3593       _pss(per_thread_states),
3594       _queues(task_queues),
3595       _root_processor(root_processor),
3596       _terminator(n_workers, _queues),
3597       _n_workers(n_workers)
3598   {}
3599 
3600   void work(uint worker_id) {
3601     if (worker_id >= _n_workers) return;  // no work needed this round
3602 
3603     double start_sec = os::elapsedTime();
3604     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3605 
3606     {
3607       ResourceMark rm;
3608       HandleMark   hm;
3609 
3610       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3611 
3612       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3613       pss->set_ref_processor(rp);
3614 
3615       double start_strong_roots_sec = os::elapsedTime();
3616 
3617       _root_processor->evacuate_roots(pss->closures(), worker_id);
3618 
3619       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3620 
3621       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3622       // treating the nmethods visited to act as roots for concurrent marking.
3623       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3624       // objects copied by the current evacuation.
3625       size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3626                                                                              pss->closures()->weak_codeblobs(),
3627                                                                              worker_id);
3628 
3629       _pss->add_cards_scanned(worker_id, cards_scanned);
3630 
3631       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3632 
3633       double term_sec = 0.0;
3634       size_t evac_term_attempts = 0;
3635       {
3636         double start = os::elapsedTime();
3637         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3638         evac.do_void();
3639 
3640         evac_term_attempts = evac.term_attempts();
3641         term_sec = evac.term_time();
3642         double elapsed_sec = os::elapsedTime() - start;
3643         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3644         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3645         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3646       }
3647 
3648       assert(pss->queue_is_empty(), "should be empty");
3649 
3650       if (log_is_enabled(Debug, gc, task, stats)) {
3651         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3652         size_t lab_waste;
3653         size_t lab_undo_waste;
3654         pss->waste(lab_waste, lab_undo_waste);
3655         _g1h->print_termination_stats(worker_id,
3656                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3657                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3658                                       term_sec * 1000.0,                          /* evac term time */
3659                                       evac_term_attempts,                         /* evac term attempts */
3660                                       lab_waste,                                  /* alloc buffer waste */
3661                                       lab_undo_waste                              /* undo waste */
3662                                       );
3663       }
3664 
3665       // Close the inner scope so that the ResourceMark and HandleMark
3666       // destructors are executed here and are included as part of the
3667       // "GC Worker Time".
3668     }
3669     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3670   }
3671 };
3672 
3673 void G1CollectedHeap::print_termination_stats_hdr() {
3674   log_debug(gc, task, stats)("GC Termination Stats");
3675   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3676   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3677   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3678 }
3679 
3680 void G1CollectedHeap::print_termination_stats(uint worker_id,
3681                                               double elapsed_ms,
3682                                               double strong_roots_ms,
3683                                               double term_ms,
3684                                               size_t term_attempts,
3685                                               size_t alloc_buffer_waste,
3686                                               size_t undo_waste) const {
3687   log_debug(gc, task, stats)
3688               ("%3d %9.2f %9.2f %6.2f "
3689                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3690                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3691                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3692                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3693                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3694                alloc_buffer_waste * HeapWordSize / K,
3695                undo_waste * HeapWordSize / K);
3696 }
3697 
3698 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3699 private:
3700   BoolObjectClosure* _is_alive;
3701   int _initial_string_table_size;
3702   int _initial_symbol_table_size;
3703 
3704   bool  _process_strings;
3705   int _strings_processed;
3706   int _strings_removed;
3707 
3708   bool  _process_symbols;
3709   int _symbols_processed;
3710   int _symbols_removed;
3711 
3712 public:
3713   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3714     AbstractGangTask("String/Symbol Unlinking"),
3715     _is_alive(is_alive),
3716     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3717     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3718 
3719     _initial_string_table_size = StringTable::the_table()->table_size();
3720     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3721     if (process_strings) {
3722       StringTable::clear_parallel_claimed_index();
3723     }
3724     if (process_symbols) {
3725       SymbolTable::clear_parallel_claimed_index();
3726     }
3727   }
3728 
3729   ~G1StringSymbolTableUnlinkTask() {
3730     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3731               "claim value %d after unlink less than initial string table size %d",
3732               StringTable::parallel_claimed_index(), _initial_string_table_size);
3733     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3734               "claim value %d after unlink less than initial symbol table size %d",
3735               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3736 
3737     log_info(gc, stringtable)(
3738         "Cleaned string and symbol table, "
3739         "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3740         "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3741         strings_processed(), strings_removed(),
3742         symbols_processed(), symbols_removed());
3743   }
3744 
3745   void work(uint worker_id) {
3746     int strings_processed = 0;
3747     int strings_removed = 0;
3748     int symbols_processed = 0;
3749     int symbols_removed = 0;
3750     if (_process_strings) {
3751       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3752       Atomic::add(strings_processed, &_strings_processed);
3753       Atomic::add(strings_removed, &_strings_removed);
3754     }
3755     if (_process_symbols) {
3756       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3757       Atomic::add(symbols_processed, &_symbols_processed);
3758       Atomic::add(symbols_removed, &_symbols_removed);
3759     }
3760   }
3761 
3762   size_t strings_processed() const { return (size_t)_strings_processed; }
3763   size_t strings_removed()   const { return (size_t)_strings_removed; }
3764 
3765   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3766   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3767 };
3768 
3769 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3770 private:
3771   static Monitor* _lock;
3772 
3773   BoolObjectClosure* const _is_alive;
3774   const bool               _unloading_occurred;
3775   const uint               _num_workers;
3776 
3777   // Variables used to claim nmethods.
3778   nmethod* _first_nmethod;
3779   volatile nmethod* _claimed_nmethod;
3780 
3781   // The list of nmethods that need to be processed by the second pass.
3782   volatile nmethod* _postponed_list;
3783   volatile uint     _num_entered_barrier;
3784 
3785  public:
3786   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3787       _is_alive(is_alive),
3788       _unloading_occurred(unloading_occurred),
3789       _num_workers(num_workers),
3790       _first_nmethod(NULL),
3791       _claimed_nmethod(NULL),
3792       _postponed_list(NULL),
3793       _num_entered_barrier(0)
3794   {
3795     nmethod::increase_unloading_clock();
3796     // Get first alive nmethod
3797     NMethodIterator iter = NMethodIterator();
3798     if(iter.next_alive()) {
3799       _first_nmethod = iter.method();
3800     }
3801     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
3802   }
3803 
3804   ~G1CodeCacheUnloadingTask() {
3805     CodeCache::verify_clean_inline_caches();
3806 
3807     CodeCache::set_needs_cache_clean(false);
3808     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3809 
3810     CodeCache::verify_icholder_relocations();
3811   }
3812 
3813  private:
3814   void add_to_postponed_list(nmethod* nm) {
3815       nmethod* old;
3816       do {
3817         old = (nmethod*)_postponed_list;
3818         nm->set_unloading_next(old);
3819       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3820   }
3821 
3822   void clean_nmethod(nmethod* nm) {
3823     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3824 
3825     if (postponed) {
3826       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3827       add_to_postponed_list(nm);
3828     }
3829 
3830     // Mark that this thread has been cleaned/unloaded.
3831     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3832     nm->set_unloading_clock(nmethod::global_unloading_clock());
3833   }
3834 
3835   void clean_nmethod_postponed(nmethod* nm) {
3836     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3837   }
3838 
3839   static const int MaxClaimNmethods = 16;
3840 
3841   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
3842     nmethod* first;
3843     NMethodIterator last;
3844 
3845     do {
3846       *num_claimed_nmethods = 0;
3847 
3848       first = (nmethod*)_claimed_nmethod;
3849       last = NMethodIterator(first);
3850 
3851       if (first != NULL) {
3852 
3853         for (int i = 0; i < MaxClaimNmethods; i++) {
3854           if (!last.next_alive()) {
3855             break;
3856           }
3857           claimed_nmethods[i] = last.method();
3858           (*num_claimed_nmethods)++;
3859         }
3860       }
3861 
3862     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3863   }
3864 
3865   nmethod* claim_postponed_nmethod() {
3866     nmethod* claim;
3867     nmethod* next;
3868 
3869     do {
3870       claim = (nmethod*)_postponed_list;
3871       if (claim == NULL) {
3872         return NULL;
3873       }
3874 
3875       next = claim->unloading_next();
3876 
3877     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3878 
3879     return claim;
3880   }
3881 
3882  public:
3883   // Mark that we're done with the first pass of nmethod cleaning.
3884   void barrier_mark(uint worker_id) {
3885     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3886     _num_entered_barrier++;
3887     if (_num_entered_barrier == _num_workers) {
3888       ml.notify_all();
3889     }
3890   }
3891 
3892   // See if we have to wait for the other workers to
3893   // finish their first-pass nmethod cleaning work.
3894   void barrier_wait(uint worker_id) {
3895     if (_num_entered_barrier < _num_workers) {
3896       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3897       while (_num_entered_barrier < _num_workers) {
3898           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3899       }
3900     }
3901   }
3902 
3903   // Cleaning and unloading of nmethods. Some work has to be postponed
3904   // to the second pass, when we know which nmethods survive.
3905   void work_first_pass(uint worker_id) {
3906     // The first nmethods is claimed by the first worker.
3907     if (worker_id == 0 && _first_nmethod != NULL) {
3908       clean_nmethod(_first_nmethod);
3909       _first_nmethod = NULL;
3910     }
3911 
3912     int num_claimed_nmethods;
3913     nmethod* claimed_nmethods[MaxClaimNmethods];
3914 
3915     while (true) {
3916       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3917 
3918       if (num_claimed_nmethods == 0) {
3919         break;
3920       }
3921 
3922       for (int i = 0; i < num_claimed_nmethods; i++) {
3923         clean_nmethod(claimed_nmethods[i]);
3924       }
3925     }
3926   }
3927 
3928   void work_second_pass(uint worker_id) {
3929     nmethod* nm;
3930     // Take care of postponed nmethods.
3931     while ((nm = claim_postponed_nmethod()) != NULL) {
3932       clean_nmethod_postponed(nm);
3933     }
3934   }
3935 };
3936 
3937 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3938 
3939 class G1KlassCleaningTask : public StackObj {
3940   BoolObjectClosure*                      _is_alive;
3941   volatile jint                           _clean_klass_tree_claimed;
3942   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3943 
3944  public:
3945   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3946       _is_alive(is_alive),
3947       _clean_klass_tree_claimed(0),
3948       _klass_iterator() {
3949   }
3950 
3951  private:
3952   bool claim_clean_klass_tree_task() {
3953     if (_clean_klass_tree_claimed) {
3954       return false;
3955     }
3956 
3957     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3958   }
3959 
3960   InstanceKlass* claim_next_klass() {
3961     Klass* klass;
3962     do {
3963       klass =_klass_iterator.next_klass();
3964     } while (klass != NULL && !klass->is_instance_klass());
3965 
3966     // this can be null so don't call InstanceKlass::cast
3967     return static_cast<InstanceKlass*>(klass);
3968   }
3969 
3970 public:
3971 
3972   void clean_klass(InstanceKlass* ik) {
3973     ik->clean_weak_instanceklass_links(_is_alive);
3974   }
3975 
3976   void work() {
3977     ResourceMark rm;
3978 
3979     // One worker will clean the subklass/sibling klass tree.
3980     if (claim_clean_klass_tree_task()) {
3981       Klass::clean_subklass_tree(_is_alive);
3982     }
3983 
3984     // All workers will help cleaning the classes,
3985     InstanceKlass* klass;
3986     while ((klass = claim_next_klass()) != NULL) {
3987       clean_klass(klass);
3988     }
3989   }
3990 };
3991 
3992 // To minimize the remark pause times, the tasks below are done in parallel.
3993 class G1ParallelCleaningTask : public AbstractGangTask {
3994 private:
3995   G1StringSymbolTableUnlinkTask _string_symbol_task;
3996   G1CodeCacheUnloadingTask      _code_cache_task;
3997   G1KlassCleaningTask           _klass_cleaning_task;
3998 
3999 public:
4000   // The constructor is run in the VMThread.
4001   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4002       AbstractGangTask("Parallel Cleaning"),
4003       _string_symbol_task(is_alive, process_strings, process_symbols),
4004       _code_cache_task(num_workers, is_alive, unloading_occurred),
4005       _klass_cleaning_task(is_alive) {
4006   }
4007 
4008   // The parallel work done by all worker threads.
4009   void work(uint worker_id) {
4010     // Do first pass of code cache cleaning.
4011     _code_cache_task.work_first_pass(worker_id);
4012 
4013     // Let the threads mark that the first pass is done.
4014     _code_cache_task.barrier_mark(worker_id);
4015 
4016     // Clean the Strings and Symbols.
4017     _string_symbol_task.work(worker_id);
4018 
4019     // Wait for all workers to finish the first code cache cleaning pass.
4020     _code_cache_task.barrier_wait(worker_id);
4021 
4022     // Do the second code cache cleaning work, which realize on
4023     // the liveness information gathered during the first pass.
4024     _code_cache_task.work_second_pass(worker_id);
4025 
4026     // Clean all klasses that were not unloaded.
4027     _klass_cleaning_task.work();
4028   }
4029 };
4030 
4031 
4032 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4033                                         bool process_strings,
4034                                         bool process_symbols,
4035                                         bool class_unloading_occurred) {
4036   uint n_workers = workers()->active_workers();
4037 
4038   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4039                                         n_workers, class_unloading_occurred);
4040   workers()->run_task(&g1_unlink_task);
4041 }
4042 
4043 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4044                                                      bool process_strings, bool process_symbols) {
4045   { // Timing scope
4046     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4047     workers()->run_task(&g1_unlink_task);
4048   }
4049 }
4050 
4051 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4052  private:
4053   DirtyCardQueueSet* _queue;
4054   G1CollectedHeap* _g1h;
4055  public:
4056   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4057     _queue(queue), _g1h(g1h) { }
4058 
4059   virtual void work(uint worker_id) {
4060     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4061     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4062 
4063     RedirtyLoggedCardTableEntryClosure cl(_g1h);
4064     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4065 
4066     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4067   }
4068 };
4069 
4070 void G1CollectedHeap::redirty_logged_cards() {
4071   double redirty_logged_cards_start = os::elapsedTime();
4072 
4073   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4074   dirty_card_queue_set().reset_for_par_iteration();
4075   workers()->run_task(&redirty_task);
4076 
4077   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4078   dcq.merge_bufferlists(&dirty_card_queue_set());
4079   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4080 
4081   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4082 }
4083 
4084 // Weak Reference Processing support
4085 
4086 // An always "is_alive" closure that is used to preserve referents.
4087 // If the object is non-null then it's alive.  Used in the preservation
4088 // of referent objects that are pointed to by reference objects
4089 // discovered by the CM ref processor.
4090 class G1AlwaysAliveClosure: public BoolObjectClosure {
4091   G1CollectedHeap* _g1;
4092 public:
4093   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4094   bool do_object_b(oop p) {
4095     if (p != NULL) {
4096       return true;
4097     }
4098     return false;
4099   }
4100 };
4101 
4102 bool G1STWIsAliveClosure::do_object_b(oop p) {
4103   // An object is reachable if it is outside the collection set,
4104   // or is inside and copied.
4105   return !_g1->is_in_cset(p) || p->is_forwarded();
4106 }
4107 
4108 // Non Copying Keep Alive closure
4109 class G1KeepAliveClosure: public OopClosure {
4110   G1CollectedHeap* _g1;
4111 public:
4112   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4113   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4114   void do_oop(oop* p) {
4115     oop obj = *p;
4116     assert(obj != NULL, "the caller should have filtered out NULL values");
4117 
4118     const InCSetState cset_state = _g1->in_cset_state(obj);
4119     if (!cset_state.is_in_cset_or_humongous()) {
4120       return;
4121     }
4122     if (cset_state.is_in_cset()) {
4123       assert( obj->is_forwarded(), "invariant" );
4124       *p = obj->forwardee();
4125     } else {
4126       assert(!obj->is_forwarded(), "invariant" );
4127       assert(cset_state.is_humongous(),
4128              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4129       _g1->set_humongous_is_live(obj);
4130     }
4131   }
4132 };
4133 
4134 // Copying Keep Alive closure - can be called from both
4135 // serial and parallel code as long as different worker
4136 // threads utilize different G1ParScanThreadState instances
4137 // and different queues.
4138 
4139 class G1CopyingKeepAliveClosure: public OopClosure {
4140   G1CollectedHeap*         _g1h;
4141   OopClosure*              _copy_non_heap_obj_cl;
4142   G1ParScanThreadState*    _par_scan_state;
4143 
4144 public:
4145   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4146                             OopClosure* non_heap_obj_cl,
4147                             G1ParScanThreadState* pss):
4148     _g1h(g1h),
4149     _copy_non_heap_obj_cl(non_heap_obj_cl),
4150     _par_scan_state(pss)
4151   {}
4152 
4153   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4154   virtual void do_oop(      oop* p) { do_oop_work(p); }
4155 
4156   template <class T> void do_oop_work(T* p) {
4157     oop obj = oopDesc::load_decode_heap_oop(p);
4158 
4159     if (_g1h->is_in_cset_or_humongous(obj)) {
4160       // If the referent object has been forwarded (either copied
4161       // to a new location or to itself in the event of an
4162       // evacuation failure) then we need to update the reference
4163       // field and, if both reference and referent are in the G1
4164       // heap, update the RSet for the referent.
4165       //
4166       // If the referent has not been forwarded then we have to keep
4167       // it alive by policy. Therefore we have copy the referent.
4168       //
4169       // If the reference field is in the G1 heap then we can push
4170       // on the PSS queue. When the queue is drained (after each
4171       // phase of reference processing) the object and it's followers
4172       // will be copied, the reference field set to point to the
4173       // new location, and the RSet updated. Otherwise we need to
4174       // use the the non-heap or metadata closures directly to copy
4175       // the referent object and update the pointer, while avoiding
4176       // updating the RSet.
4177 
4178       if (_g1h->is_in_g1_reserved(p)) {
4179         _par_scan_state->push_on_queue(p);
4180       } else {
4181         assert(!Metaspace::contains((const void*)p),
4182                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4183         _copy_non_heap_obj_cl->do_oop(p);
4184       }
4185     }
4186   }
4187 };
4188 
4189 // Serial drain queue closure. Called as the 'complete_gc'
4190 // closure for each discovered list in some of the
4191 // reference processing phases.
4192 
4193 class G1STWDrainQueueClosure: public VoidClosure {
4194 protected:
4195   G1CollectedHeap* _g1h;
4196   G1ParScanThreadState* _par_scan_state;
4197 
4198   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4199 
4200 public:
4201   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4202     _g1h(g1h),
4203     _par_scan_state(pss)
4204   { }
4205 
4206   void do_void() {
4207     G1ParScanThreadState* const pss = par_scan_state();
4208     pss->trim_queue();
4209   }
4210 };
4211 
4212 // Parallel Reference Processing closures
4213 
4214 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4215 // processing during G1 evacuation pauses.
4216 
4217 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4218 private:
4219   G1CollectedHeap*          _g1h;
4220   G1ParScanThreadStateSet*  _pss;
4221   RefToScanQueueSet*        _queues;
4222   WorkGang*                 _workers;
4223   uint                      _active_workers;
4224 
4225 public:
4226   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4227                            G1ParScanThreadStateSet* per_thread_states,
4228                            WorkGang* workers,
4229                            RefToScanQueueSet *task_queues,
4230                            uint n_workers) :
4231     _g1h(g1h),
4232     _pss(per_thread_states),
4233     _queues(task_queues),
4234     _workers(workers),
4235     _active_workers(n_workers)
4236   {
4237     g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4238   }
4239 
4240   // Executes the given task using concurrent marking worker threads.
4241   virtual void execute(ProcessTask& task);
4242   virtual void execute(EnqueueTask& task);
4243 };
4244 
4245 // Gang task for possibly parallel reference processing
4246 
4247 class G1STWRefProcTaskProxy: public AbstractGangTask {
4248   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4249   ProcessTask&     _proc_task;
4250   G1CollectedHeap* _g1h;
4251   G1ParScanThreadStateSet* _pss;
4252   RefToScanQueueSet* _task_queues;
4253   ParallelTaskTerminator* _terminator;
4254 
4255 public:
4256   G1STWRefProcTaskProxy(ProcessTask& proc_task,
4257                         G1CollectedHeap* g1h,
4258                         G1ParScanThreadStateSet* per_thread_states,
4259                         RefToScanQueueSet *task_queues,
4260                         ParallelTaskTerminator* terminator) :
4261     AbstractGangTask("Process reference objects in parallel"),
4262     _proc_task(proc_task),
4263     _g1h(g1h),
4264     _pss(per_thread_states),
4265     _task_queues(task_queues),
4266     _terminator(terminator)
4267   {}
4268 
4269   virtual void work(uint worker_id) {
4270     // The reference processing task executed by a single worker.
4271     ResourceMark rm;
4272     HandleMark   hm;
4273 
4274     G1STWIsAliveClosure is_alive(_g1h);
4275 
4276     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4277     pss->set_ref_processor(NULL);
4278 
4279     // Keep alive closure.
4280     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4281 
4282     // Complete GC closure
4283     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4284 
4285     // Call the reference processing task's work routine.
4286     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4287 
4288     // Note we cannot assert that the refs array is empty here as not all
4289     // of the processing tasks (specifically phase2 - pp2_work) execute
4290     // the complete_gc closure (which ordinarily would drain the queue) so
4291     // the queue may not be empty.
4292   }
4293 };
4294 
4295 // Driver routine for parallel reference processing.
4296 // Creates an instance of the ref processing gang
4297 // task and has the worker threads execute it.
4298 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4299   assert(_workers != NULL, "Need parallel worker threads.");
4300 
4301   ParallelTaskTerminator terminator(_active_workers, _queues);
4302   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4303 
4304   _workers->run_task(&proc_task_proxy);
4305 }
4306 
4307 // Gang task for parallel reference enqueueing.
4308 
4309 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4310   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4311   EnqueueTask& _enq_task;
4312 
4313 public:
4314   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4315     AbstractGangTask("Enqueue reference objects in parallel"),
4316     _enq_task(enq_task)
4317   { }
4318 
4319   virtual void work(uint worker_id) {
4320     _enq_task.work(worker_id);
4321   }
4322 };
4323 
4324 // Driver routine for parallel reference enqueueing.
4325 // Creates an instance of the ref enqueueing gang
4326 // task and has the worker threads execute it.
4327 
4328 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4329   assert(_workers != NULL, "Need parallel worker threads.");
4330 
4331   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4332 
4333   _workers->run_task(&enq_task_proxy);
4334 }
4335 
4336 // End of weak reference support closures
4337 
4338 // Abstract task used to preserve (i.e. copy) any referent objects
4339 // that are in the collection set and are pointed to by reference
4340 // objects discovered by the CM ref processor.
4341 
4342 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4343 protected:
4344   G1CollectedHeap*         _g1h;
4345   G1ParScanThreadStateSet* _pss;
4346   RefToScanQueueSet*       _queues;
4347   ParallelTaskTerminator   _terminator;
4348   uint                     _n_workers;
4349 
4350 public:
4351   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4352     AbstractGangTask("ParPreserveCMReferents"),
4353     _g1h(g1h),
4354     _pss(per_thread_states),
4355     _queues(task_queues),
4356     _terminator(workers, _queues),
4357     _n_workers(workers)
4358   {
4359     g1h->ref_processor_cm()->set_active_mt_degree(workers);
4360   }
4361 
4362   void work(uint worker_id) {
4363     G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4364 
4365     ResourceMark rm;
4366     HandleMark   hm;
4367 
4368     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4369     pss->set_ref_processor(NULL);
4370     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4371 
4372     // Is alive closure
4373     G1AlwaysAliveClosure always_alive(_g1h);
4374 
4375     // Copying keep alive closure. Applied to referent objects that need
4376     // to be copied.
4377     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4378 
4379     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4380 
4381     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4382     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4383 
4384     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4385     // So this must be true - but assert just in case someone decides to
4386     // change the worker ids.
4387     assert(worker_id < limit, "sanity");
4388     assert(!rp->discovery_is_atomic(), "check this code");
4389 
4390     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4391     for (uint idx = worker_id; idx < limit; idx += stride) {
4392       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4393 
4394       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4395       while (iter.has_next()) {
4396         // Since discovery is not atomic for the CM ref processor, we
4397         // can see some null referent objects.
4398         iter.load_ptrs(DEBUG_ONLY(true));
4399         oop ref = iter.obj();
4400 
4401         // This will filter nulls.
4402         if (iter.is_referent_alive()) {
4403           iter.make_referent_alive();
4404         }
4405         iter.move_to_next();
4406       }
4407     }
4408 
4409     // Drain the queue - which may cause stealing
4410     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4411     drain_queue.do_void();
4412     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4413     assert(pss->queue_is_empty(), "should be");
4414   }
4415 };
4416 
4417 void G1CollectedHeap::process_weak_jni_handles() {
4418   double ref_proc_start = os::elapsedTime();
4419 
4420   G1STWIsAliveClosure is_alive(this);
4421   G1KeepAliveClosure keep_alive(this);
4422   JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4423 
4424   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4425   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4426 }
4427 
4428 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4429   // Any reference objects, in the collection set, that were 'discovered'
4430   // by the CM ref processor should have already been copied (either by
4431   // applying the external root copy closure to the discovered lists, or
4432   // by following an RSet entry).
4433   //
4434   // But some of the referents, that are in the collection set, that these
4435   // reference objects point to may not have been copied: the STW ref
4436   // processor would have seen that the reference object had already
4437   // been 'discovered' and would have skipped discovering the reference,
4438   // but would not have treated the reference object as a regular oop.
4439   // As a result the copy closure would not have been applied to the
4440   // referent object.
4441   //
4442   // We need to explicitly copy these referent objects - the references
4443   // will be processed at the end of remarking.
4444   //
4445   // We also need to do this copying before we process the reference
4446   // objects discovered by the STW ref processor in case one of these
4447   // referents points to another object which is also referenced by an
4448   // object discovered by the STW ref processor.
4449   double preserve_cm_referents_time = 0.0;
4450 
4451   // To avoid spawning task when there is no work to do, check that
4452   // a concurrent cycle is active and that some references have been
4453   // discovered.
4454   if (concurrent_mark()->cmThread()->during_cycle() &&
4455       ref_processor_cm()->has_discovered_references()) {
4456     double preserve_cm_referents_start = os::elapsedTime();
4457     uint no_of_gc_workers = workers()->active_workers();
4458     G1ParPreserveCMReferentsTask keep_cm_referents(this,
4459                                                    per_thread_states,
4460                                                    no_of_gc_workers,
4461                                                    _task_queues);
4462     workers()->run_task(&keep_cm_referents);
4463     preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4464   }
4465 
4466   g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4467 }
4468 
4469 // Weak Reference processing during an evacuation pause (part 1).
4470 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4471   double ref_proc_start = os::elapsedTime();
4472 
4473   ReferenceProcessor* rp = _ref_processor_stw;
4474   assert(rp->discovery_enabled(), "should have been enabled");
4475 
4476   // Closure to test whether a referent is alive.
4477   G1STWIsAliveClosure is_alive(this);
4478 
4479   // Even when parallel reference processing is enabled, the processing
4480   // of JNI refs is serial and performed serially by the current thread
4481   // rather than by a worker. The following PSS will be used for processing
4482   // JNI refs.
4483 
4484   // Use only a single queue for this PSS.
4485   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4486   pss->set_ref_processor(NULL);
4487   assert(pss->queue_is_empty(), "pre-condition");
4488 
4489   // Keep alive closure.
4490   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4491 
4492   // Serial Complete GC closure
4493   G1STWDrainQueueClosure drain_queue(this, pss);
4494 
4495   // Setup the soft refs policy...
4496   rp->setup_policy(false);
4497 
4498   ReferenceProcessorStats stats;
4499   if (!rp->processing_is_mt()) {
4500     // Serial reference processing...
4501     stats = rp->process_discovered_references(&is_alive,
4502                                               &keep_alive,
4503                                               &drain_queue,
4504                                               NULL,
4505                                               _gc_timer_stw);
4506   } else {
4507     uint no_of_gc_workers = workers()->active_workers();
4508 
4509     // Parallel reference processing
4510     assert(no_of_gc_workers <= rp->max_num_q(),
4511            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4512            no_of_gc_workers,  rp->max_num_q());
4513 
4514     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4515     stats = rp->process_discovered_references(&is_alive,
4516                                               &keep_alive,
4517                                               &drain_queue,
4518                                               &par_task_executor,
4519                                               _gc_timer_stw);
4520   }
4521 
4522   _gc_tracer_stw->report_gc_reference_stats(stats);
4523 
4524   // We have completed copying any necessary live referent objects.
4525   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4526 
4527   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4528   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4529 }
4530 
4531 // Weak Reference processing during an evacuation pause (part 2).
4532 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4533   double ref_enq_start = os::elapsedTime();
4534 
4535   ReferenceProcessor* rp = _ref_processor_stw;
4536   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4537 
4538   // Now enqueue any remaining on the discovered lists on to
4539   // the pending list.
4540   if (!rp->processing_is_mt()) {
4541     // Serial reference processing...
4542     rp->enqueue_discovered_references();
4543   } else {
4544     // Parallel reference enqueueing
4545 
4546     uint n_workers = workers()->active_workers();
4547 
4548     assert(n_workers <= rp->max_num_q(),
4549            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4550            n_workers,  rp->max_num_q());
4551 
4552     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4553     rp->enqueue_discovered_references(&par_task_executor);
4554   }
4555 
4556   rp->verify_no_references_recorded();
4557   assert(!rp->discovery_enabled(), "should have been disabled");
4558 
4559   // FIXME
4560   // CM's reference processing also cleans up the string and symbol tables.
4561   // Should we do that here also? We could, but it is a serial operation
4562   // and could significantly increase the pause time.
4563 
4564   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4565   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4566 }
4567 
4568 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4569   double merge_pss_time_start = os::elapsedTime();
4570   per_thread_states->flush();
4571   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4572 }
4573 
4574 void G1CollectedHeap::pre_evacuate_collection_set() {
4575   _expand_heap_after_alloc_failure = true;
4576   _evacuation_failed = false;
4577 
4578   // Disable the hot card cache.
4579   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4580   hot_card_cache->reset_hot_cache_claimed_index();
4581   hot_card_cache->set_use_cache(false);
4582 
4583   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4584 }
4585 
4586 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4587   // Should G1EvacuationFailureALot be in effect for this GC?
4588   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4589 
4590   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4591   double start_par_time_sec = os::elapsedTime();
4592   double end_par_time_sec;
4593 
4594   {
4595     const uint n_workers = workers()->active_workers();
4596     G1RootProcessor root_processor(this, n_workers);
4597     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4598     // InitialMark needs claim bits to keep track of the marked-through CLDs.
4599     if (collector_state()->during_initial_mark_pause()) {
4600       ClassLoaderDataGraph::clear_claimed_marks();
4601     }
4602 
4603     print_termination_stats_hdr();
4604 
4605     workers()->run_task(&g1_par_task);
4606     end_par_time_sec = os::elapsedTime();
4607 
4608     // Closing the inner scope will execute the destructor
4609     // for the G1RootProcessor object. We record the current
4610     // elapsed time before closing the scope so that time
4611     // taken for the destructor is NOT included in the
4612     // reported parallel time.
4613   }
4614 
4615   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4616 
4617   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4618   phase_times->record_par_time(par_time_ms);
4619 
4620   double code_root_fixup_time_ms =
4621         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4622   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4623 }
4624 
4625 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4626   // Process any discovered reference objects - we have
4627   // to do this _before_ we retire the GC alloc regions
4628   // as we may have to copy some 'reachable' referent
4629   // objects (and their reachable sub-graphs) that were
4630   // not copied during the pause.
4631   if (g1_policy()->should_process_references()) {
4632     preserve_cm_referents(per_thread_states);
4633     process_discovered_references(per_thread_states);
4634   } else {
4635     ref_processor_stw()->verify_no_references_recorded();
4636     process_weak_jni_handles();
4637   }
4638 
4639   if (G1StringDedup::is_enabled()) {
4640     double fixup_start = os::elapsedTime();
4641 
4642     G1STWIsAliveClosure is_alive(this);
4643     G1KeepAliveClosure keep_alive(this);
4644     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4645 
4646     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4647     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4648   }
4649 
4650   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4651 
4652   if (evacuation_failed()) {
4653     restore_after_evac_failure();
4654 
4655     // Reset the G1EvacuationFailureALot counters and flags
4656     // Note: the values are reset only when an actual
4657     // evacuation failure occurs.
4658     NOT_PRODUCT(reset_evacuation_should_fail();)
4659   }
4660 
4661   // Enqueue any remaining references remaining on the STW
4662   // reference processor's discovered lists. We need to do
4663   // this after the card table is cleaned (and verified) as
4664   // the act of enqueueing entries on to the pending list
4665   // will log these updates (and dirty their associated
4666   // cards). We need these updates logged to update any
4667   // RSets.
4668   if (g1_policy()->should_process_references()) {
4669     enqueue_discovered_references(per_thread_states);
4670   } else {
4671     g1_policy()->phase_times()->record_ref_enq_time(0);
4672   }
4673 
4674   _allocator->release_gc_alloc_regions(evacuation_info);
4675 
4676   merge_per_thread_state_info(per_thread_states);
4677 
4678   // Reset and re-enable the hot card cache.
4679   // Note the counts for the cards in the regions in the
4680   // collection set are reset when the collection set is freed.
4681   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4682   hot_card_cache->reset_hot_cache();
4683   hot_card_cache->set_use_cache(true);
4684 
4685   purge_code_root_memory();
4686 
4687   redirty_logged_cards();
4688 #if defined(COMPILER2) || INCLUDE_JVMCI
4689   DerivedPointerTable::update_pointers();
4690 #endif
4691 }
4692 
4693 void G1CollectedHeap::record_obj_copy_mem_stats() {
4694   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4695 
4696   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4697                                                create_g1_evac_summary(&_old_evac_stats));
4698 }
4699 
4700 void G1CollectedHeap::free_region(HeapRegion* hr,
4701                                   FreeRegionList* free_list,
4702                                   bool par,
4703                                   bool locked) {
4704   assert(!hr->is_free(), "the region should not be free");
4705   assert(!hr->is_empty(), "the region should not be empty");
4706   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4707   assert(free_list != NULL, "pre-condition");
4708 
4709   if (G1VerifyBitmaps) {
4710     MemRegion mr(hr->bottom(), hr->end());
4711     concurrent_mark()->clearRangePrevBitmap(mr);
4712   }
4713 
4714   // Clear the card counts for this region.
4715   // Note: we only need to do this if the region is not young
4716   // (since we don't refine cards in young regions).
4717   if (!hr->is_young()) {
4718     _cg1r->hot_card_cache()->reset_card_counts(hr);
4719   }
4720   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
4721   free_list->add_ordered(hr);
4722 }
4723 
4724 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4725                                             FreeRegionList* free_list,
4726                                             bool par) {
4727   assert(hr->is_humongous(), "this is only for humongous regions");
4728   assert(free_list != NULL, "pre-condition");
4729   hr->clear_humongous();
4730   free_region(hr, free_list, par);
4731 }
4732 
4733 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4734                                            const uint humongous_regions_removed) {
4735   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4736     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4737     _old_set.bulk_remove(old_regions_removed);
4738     _humongous_set.bulk_remove(humongous_regions_removed);
4739   }
4740 
4741 }
4742 
4743 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4744   assert(list != NULL, "list can't be null");
4745   if (!list->is_empty()) {
4746     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4747     _hrm.insert_list_into_free_list(list);
4748   }
4749 }
4750 
4751 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4752   decrease_used(bytes);
4753 }
4754 
4755 class G1ParCleanupCTTask : public AbstractGangTask {
4756   G1SATBCardTableModRefBS* _ct_bs;
4757   G1CollectedHeap* _g1h;
4758   HeapRegion* volatile _su_head;
4759 public:
4760   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
4761                      G1CollectedHeap* g1h) :
4762     AbstractGangTask("G1 Par Cleanup CT Task"),
4763     _ct_bs(ct_bs), _g1h(g1h) { }
4764 
4765   void work(uint worker_id) {
4766     HeapRegion* r;
4767     while (r = _g1h->pop_dirty_cards_region()) {
4768       clear_cards(r);
4769     }
4770   }
4771 
4772   void clear_cards(HeapRegion* r) {
4773     // Cards of the survivors should have already been dirtied.
4774     if (!r->is_survivor()) {
4775       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4776     }
4777   }
4778 };
4779 
4780 class G1ParScrubRemSetTask: public AbstractGangTask {
4781 protected:
4782   G1RemSet* _g1rs;
4783   HeapRegionClaimer _hrclaimer;
4784 
4785 public:
4786   G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4787     AbstractGangTask("G1 ScrubRS"),
4788     _g1rs(g1_rs),
4789     _hrclaimer(num_workers) {
4790   }
4791 
4792   void work(uint worker_id) {
4793     _g1rs->scrub(worker_id, &_hrclaimer);
4794   }
4795 };
4796 
4797 void G1CollectedHeap::scrub_rem_set() {
4798   uint num_workers = workers()->active_workers();
4799   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4800   workers()->run_task(&g1_par_scrub_rs_task);
4801 }
4802 
4803 void G1CollectedHeap::cleanUpCardTable() {
4804   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
4805   double start = os::elapsedTime();
4806 
4807   {
4808     // Iterate over the dirty cards region list.
4809     G1ParCleanupCTTask cleanup_task(ct_bs, this);
4810 
4811     workers()->run_task(&cleanup_task);
4812 #ifndef PRODUCT
4813     // Need to synchronize with concurrent cleanup since it needs to
4814     // finish its card table clearing before we can verify.
4815     wait_while_free_regions_coming();
4816     _verifier->verify_card_table_cleanup();
4817 #endif
4818   }
4819 
4820   double elapsed = os::elapsedTime() - start;
4821   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
4822 }
4823 
4824 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4825   size_t pre_used = 0;
4826   FreeRegionList local_free_list("Local List for CSet Freeing");
4827 
4828   double young_time_ms     = 0.0;
4829   double non_young_time_ms = 0.0;
4830 
4831   // Since the collection set is a superset of the the young list,
4832   // all we need to do to clear the young list is clear its
4833   // head and length, and unlink any young regions in the code below
4834   _young_list->clear();
4835 
4836   G1Policy* policy = g1_policy();
4837 
4838   double start_sec = os::elapsedTime();
4839   bool non_young = true;
4840 
4841   HeapRegion* cur = cs_head;
4842   int age_bound = -1;
4843   size_t rs_lengths = 0;
4844 
4845   while (cur != NULL) {
4846     assert(!is_on_master_free_list(cur), "sanity");
4847     if (non_young) {
4848       if (cur->is_young()) {
4849         double end_sec = os::elapsedTime();
4850         double elapsed_ms = (end_sec - start_sec) * 1000.0;
4851         non_young_time_ms += elapsed_ms;
4852 
4853         start_sec = os::elapsedTime();
4854         non_young = false;
4855       }
4856     } else {
4857       if (!cur->is_young()) {
4858         double end_sec = os::elapsedTime();
4859         double elapsed_ms = (end_sec - start_sec) * 1000.0;
4860         young_time_ms += elapsed_ms;
4861 
4862         start_sec = os::elapsedTime();
4863         non_young = true;
4864       }
4865     }
4866 
4867     rs_lengths += cur->rem_set()->occupied_locked();
4868 
4869     HeapRegion* next = cur->next_in_collection_set();
4870     assert(cur->in_collection_set(), "bad CS");
4871     cur->set_next_in_collection_set(NULL);
4872     clear_in_cset(cur);
4873 
4874     if (cur->is_young()) {
4875       int index = cur->young_index_in_cset();
4876       assert(index != -1, "invariant");
4877       assert((uint) index < collection_set()->young_region_length(), "invariant");
4878       size_t words_survived = surviving_young_words[index];
4879       cur->record_surv_words_in_group(words_survived);
4880 
4881       // At this point the we have 'popped' cur from the collection set
4882       // (linked via next_in_collection_set()) but it is still in the
4883       // young list (linked via next_young_region()). Clear the
4884       // _next_young_region field.
4885       cur->set_next_young_region(NULL);
4886     } else {
4887       int index = cur->young_index_in_cset();
4888       assert(index == -1, "invariant");
4889     }
4890 
4891     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4892             (!cur->is_young() && cur->young_index_in_cset() == -1),
4893             "invariant" );
4894 
4895     if (!cur->evacuation_failed()) {
4896       MemRegion used_mr = cur->used_region();
4897 
4898       // And the region is empty.
4899       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
4900       pre_used += cur->used();
4901       free_region(cur, &local_free_list, false /* par */, true /* locked */);
4902     } else {
4903       cur->uninstall_surv_rate_group();
4904       if (cur->is_young()) {
4905         cur->set_young_index_in_cset(-1);
4906       }
4907       cur->set_evacuation_failed(false);
4908       // When moving a young gen region to old gen, we "allocate" that whole region
4909       // there. This is in addition to any already evacuated objects. Notify the
4910       // policy about that.
4911       // Old gen regions do not cause an additional allocation: both the objects
4912       // still in the region and the ones already moved are accounted for elsewhere.
4913       if (cur->is_young()) {
4914         policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
4915       }
4916       // The region is now considered to be old.
4917       cur->set_old();
4918       // Do some allocation statistics accounting. Regions that failed evacuation
4919       // are always made old, so there is no need to update anything in the young
4920       // gen statistics, but we need to update old gen statistics.
4921       size_t used_words = cur->marked_bytes() / HeapWordSize;
4922       _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
4923       _old_set.add(cur);
4924       evacuation_info.increment_collectionset_used_after(cur->used());
4925     }
4926     cur = next;
4927   }
4928 
4929   evacuation_info.set_regions_freed(local_free_list.length());
4930   policy->record_max_rs_lengths(rs_lengths);
4931   policy->cset_regions_freed();
4932 
4933   double end_sec = os::elapsedTime();
4934   double elapsed_ms = (end_sec - start_sec) * 1000.0;
4935 
4936   if (non_young) {
4937     non_young_time_ms += elapsed_ms;
4938   } else {
4939     young_time_ms += elapsed_ms;
4940   }
4941 
4942   prepend_to_freelist(&local_free_list);
4943   decrement_summary_bytes(pre_used);
4944   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
4945   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
4946 }
4947 
4948 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4949  private:
4950   FreeRegionList* _free_region_list;
4951   HeapRegionSet* _proxy_set;
4952   uint _humongous_regions_removed;
4953   size_t _freed_bytes;
4954  public:
4955 
4956   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4957     _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4958   }
4959 
4960   virtual bool doHeapRegion(HeapRegion* r) {
4961     if (!r->is_starts_humongous()) {
4962       return false;
4963     }
4964 
4965     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4966 
4967     oop obj = (oop)r->bottom();
4968     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4969 
4970     // The following checks whether the humongous object is live are sufficient.
4971     // The main additional check (in addition to having a reference from the roots
4972     // or the young gen) is whether the humongous object has a remembered set entry.
4973     //
4974     // A humongous object cannot be live if there is no remembered set for it
4975     // because:
4976     // - there can be no references from within humongous starts regions referencing
4977     // the object because we never allocate other objects into them.
4978     // (I.e. there are no intra-region references that may be missed by the
4979     // remembered set)
4980     // - as soon there is a remembered set entry to the humongous starts region
4981     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4982     // until the end of a concurrent mark.
4983     //
4984     // It is not required to check whether the object has been found dead by marking
4985     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4986     // all objects allocated during that time are considered live.
4987     // SATB marking is even more conservative than the remembered set.
4988     // So if at this point in the collection there is no remembered set entry,
4989     // nobody has a reference to it.
4990     // At the start of collection we flush all refinement logs, and remembered sets
4991     // are completely up-to-date wrt to references to the humongous object.
4992     //
4993     // Other implementation considerations:
4994     // - never consider object arrays at this time because they would pose
4995     // considerable effort for cleaning up the the remembered sets. This is
4996     // required because stale remembered sets might reference locations that
4997     // are currently allocated into.
4998     uint region_idx = r->hrm_index();
4999     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5000         !r->rem_set()->is_empty()) {
5001       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",
5002                                region_idx,
5003                                (size_t)obj->size() * HeapWordSize,
5004                                p2i(r->bottom()),
5005                                r->rem_set()->occupied(),
5006                                r->rem_set()->strong_code_roots_list_length(),
5007                                next_bitmap->isMarked(r->bottom()),
5008                                g1h->is_humongous_reclaim_candidate(region_idx),
5009                                obj->is_typeArray()
5010                               );
5011       return false;
5012     }
5013 
5014     guarantee(obj->is_typeArray(),
5015               "Only eagerly reclaiming type arrays is supported, but the object "
5016               PTR_FORMAT " is not.", p2i(r->bottom()));
5017 
5018     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",
5019                              region_idx,
5020                              (size_t)obj->size() * HeapWordSize,
5021                              p2i(r->bottom()),
5022                              r->rem_set()->occupied(),
5023                              r->rem_set()->strong_code_roots_list_length(),
5024                              next_bitmap->isMarked(r->bottom()),
5025                              g1h->is_humongous_reclaim_candidate(region_idx),
5026                              obj->is_typeArray()
5027                             );
5028 
5029     // Need to clear mark bit of the humongous object if already set.
5030     if (next_bitmap->isMarked(r->bottom())) {
5031       next_bitmap->clear(r->bottom());
5032     }
5033     do {
5034       HeapRegion* next = g1h->next_region_in_humongous(r);
5035       _freed_bytes += r->used();
5036       r->set_containing_set(NULL);
5037       _humongous_regions_removed++;
5038       g1h->free_humongous_region(r, _free_region_list, false);
5039       r = next;
5040     } while (r != NULL);
5041 
5042     return false;
5043   }
5044 
5045   uint humongous_free_count() {
5046     return _humongous_regions_removed;
5047   }
5048 
5049   size_t bytes_freed() const {
5050     return _freed_bytes;
5051   }
5052 };
5053 
5054 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5055   assert_at_safepoint(true);
5056 
5057   if (!G1EagerReclaimHumongousObjects ||
5058       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5059     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5060     return;
5061   }
5062 
5063   double start_time = os::elapsedTime();
5064 
5065   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5066 
5067   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5068   heap_region_iterate(&cl);
5069 
5070   remove_from_old_sets(0, cl.humongous_free_count());
5071 
5072   G1HRPrinter* hrp = hr_printer();
5073   if (hrp->is_active()) {
5074     FreeRegionListIterator iter(&local_cleanup_list);
5075     while (iter.more_available()) {
5076       HeapRegion* hr = iter.get_next();
5077       hrp->cleanup(hr);
5078     }
5079   }
5080 
5081   prepend_to_freelist(&local_cleanup_list);
5082   decrement_summary_bytes(cl.bytes_freed());
5083 
5084   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5085                                                                     cl.humongous_free_count());
5086 }
5087 
5088 // This routine is similar to the above but does not record
5089 // any policy statistics or update free lists; we are abandoning
5090 // the current incremental collection set in preparation of a
5091 // full collection. After the full GC we will start to build up
5092 // the incremental collection set again.
5093 // This is only called when we're doing a full collection
5094 // and is immediately followed by the tearing down of the young list.
5095 
5096 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5097   HeapRegion* cur = cs_head;
5098 
5099   while (cur != NULL) {
5100     HeapRegion* next = cur->next_in_collection_set();
5101     assert(cur->in_collection_set(), "bad CS");
5102     cur->set_next_in_collection_set(NULL);
5103     clear_in_cset(cur);
5104     cur->set_young_index_in_cset(-1);
5105     cur = next;
5106   }
5107 }
5108 
5109 void G1CollectedHeap::set_free_regions_coming() {
5110   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5111 
5112   assert(!free_regions_coming(), "pre-condition");
5113   _free_regions_coming = true;
5114 }
5115 
5116 void G1CollectedHeap::reset_free_regions_coming() {
5117   assert(free_regions_coming(), "pre-condition");
5118 
5119   {
5120     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5121     _free_regions_coming = false;
5122     SecondaryFreeList_lock->notify_all();
5123   }
5124 
5125   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5126 }
5127 
5128 void G1CollectedHeap::wait_while_free_regions_coming() {
5129   // Most of the time we won't have to wait, so let's do a quick test
5130   // first before we take the lock.
5131   if (!free_regions_coming()) {
5132     return;
5133   }
5134 
5135   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5136 
5137   {
5138     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5139     while (free_regions_coming()) {
5140       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5141     }
5142   }
5143 
5144   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5145 }
5146 
5147 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5148   return _allocator->is_retained_old_region(hr);
5149 }
5150 
5151 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5152   _young_list->push_region(hr);
5153 }
5154 
5155 class NoYoungRegionsClosure: public HeapRegionClosure {
5156 private:
5157   bool _success;
5158 public:
5159   NoYoungRegionsClosure() : _success(true) { }
5160   bool doHeapRegion(HeapRegion* r) {
5161     if (r->is_young()) {
5162       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5163                             p2i(r->bottom()), p2i(r->end()));
5164       _success = false;
5165     }
5166     return false;
5167   }
5168   bool success() { return _success; }
5169 };
5170 
5171 bool G1CollectedHeap::check_young_list_empty(bool check_heap) {
5172   bool ret = _young_list->check_list_empty();
5173 
5174   if (check_heap) {
5175     NoYoungRegionsClosure closure;
5176     heap_region_iterate(&closure);
5177     ret = ret && closure.success();
5178   }
5179 
5180   return ret;
5181 }
5182 
5183 class TearDownRegionSetsClosure : public HeapRegionClosure {
5184 private:
5185   HeapRegionSet *_old_set;
5186 
5187 public:
5188   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5189 
5190   bool doHeapRegion(HeapRegion* r) {
5191     if (r->is_old()) {
5192       _old_set->remove(r);
5193     } else {
5194       // We ignore free regions, we'll empty the free list afterwards.
5195       // We ignore young regions, we'll empty the young list afterwards.
5196       // We ignore humongous regions, we're not tearing down the
5197       // humongous regions set.
5198       assert(r->is_free() || r->is_young() || r->is_humongous(),
5199              "it cannot be another type");
5200     }
5201     return false;
5202   }
5203 
5204   ~TearDownRegionSetsClosure() {
5205     assert(_old_set->is_empty(), "post-condition");
5206   }
5207 };
5208 
5209 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5210   assert_at_safepoint(true /* should_be_vm_thread */);
5211 
5212   if (!free_list_only) {
5213     TearDownRegionSetsClosure cl(&_old_set);
5214     heap_region_iterate(&cl);
5215 
5216     // Note that emptying the _young_list is postponed and instead done as
5217     // the first step when rebuilding the regions sets again. The reason for
5218     // this is that during a full GC string deduplication needs to know if
5219     // a collected region was young or old when the full GC was initiated.
5220   }
5221   _hrm.remove_all_free_regions();
5222 }
5223 
5224 void G1CollectedHeap::increase_used(size_t bytes) {
5225   _summary_bytes_used += bytes;
5226 }
5227 
5228 void G1CollectedHeap::decrease_used(size_t bytes) {
5229   assert(_summary_bytes_used >= bytes,
5230          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5231          _summary_bytes_used, bytes);
5232   _summary_bytes_used -= bytes;
5233 }
5234 
5235 void G1CollectedHeap::set_used(size_t bytes) {
5236   _summary_bytes_used = bytes;
5237 }
5238 
5239 class RebuildRegionSetsClosure : public HeapRegionClosure {
5240 private:
5241   bool            _free_list_only;
5242   HeapRegionSet*   _old_set;
5243   HeapRegionManager*   _hrm;
5244   size_t          _total_used;
5245 
5246 public:
5247   RebuildRegionSetsClosure(bool free_list_only,
5248                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5249     _free_list_only(free_list_only),
5250     _old_set(old_set), _hrm(hrm), _total_used(0) {
5251     assert(_hrm->num_free_regions() == 0, "pre-condition");
5252     if (!free_list_only) {
5253       assert(_old_set->is_empty(), "pre-condition");
5254     }
5255   }
5256 
5257   bool doHeapRegion(HeapRegion* r) {
5258     if (r->is_empty()) {
5259       // Add free regions to the free list
5260       r->set_free();
5261       r->set_allocation_context(AllocationContext::system());
5262       _hrm->insert_into_free_list(r);
5263     } else if (!_free_list_only) {
5264       assert(!r->is_young(), "we should not come across young regions");
5265 
5266       if (r->is_humongous()) {
5267         // We ignore humongous regions. We left the humongous set unchanged.
5268       } else {
5269         // Objects that were compacted would have ended up on regions
5270         // that were previously old or free.  Archive regions (which are
5271         // old) will not have been touched.
5272         assert(r->is_free() || r->is_old(), "invariant");
5273         // We now consider them old, so register as such. Leave
5274         // archive regions set that way, however, while still adding
5275         // them to the old set.
5276         if (!r->is_archive()) {
5277           r->set_old();
5278         }
5279         _old_set->add(r);
5280       }
5281       _total_used += r->used();
5282     }
5283 
5284     return false;
5285   }
5286 
5287   size_t total_used() {
5288     return _total_used;
5289   }
5290 };
5291 
5292 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5293   assert_at_safepoint(true /* should_be_vm_thread */);
5294 
5295   if (!free_list_only) {
5296     _young_list->empty_list();
5297   }
5298 
5299   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5300   heap_region_iterate(&cl);
5301 
5302   if (!free_list_only) {
5303     set_used(cl.total_used());
5304     if (_archive_allocator != NULL) {
5305       _archive_allocator->clear_used();
5306     }
5307   }
5308   assert(used_unlocked() == recalculate_used(),
5309          "inconsistent used_unlocked(), "
5310          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5311          used_unlocked(), recalculate_used());
5312 }
5313 
5314 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5315   _refine_cte_cl->set_concurrent(concurrent);
5316 }
5317 
5318 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5319   HeapRegion* hr = heap_region_containing(p);
5320   return hr->is_in(p);
5321 }
5322 
5323 // Methods for the mutator alloc region
5324 
5325 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5326                                                       bool force) {
5327   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5328   assert(!force || g1_policy()->can_expand_young_list(),
5329          "if force is true we should be able to expand the young list");
5330   bool young_list_full = g1_policy()->is_young_list_full();
5331   if (force || !young_list_full) {
5332     HeapRegion* new_alloc_region = new_region(word_size,
5333                                               false /* is_old */,
5334                                               false /* do_expand */);
5335     if (new_alloc_region != NULL) {
5336       set_region_short_lived_locked(new_alloc_region);
5337       _hr_printer.alloc(new_alloc_region, young_list_full);
5338       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5339       return new_alloc_region;
5340     }
5341   }
5342   return NULL;
5343 }
5344 
5345 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5346                                                   size_t allocated_bytes) {
5347   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5348   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5349 
5350   collection_set()->add_eden_region(alloc_region);
5351   increase_used(allocated_bytes);
5352   _hr_printer.retire(alloc_region);
5353   // We update the eden sizes here, when the region is retired,
5354   // instead of when it's allocated, since this is the point that its
5355   // used space has been recored in _summary_bytes_used.
5356   g1mm()->update_eden_size();
5357 }
5358 
5359 // Methods for the GC alloc regions
5360 
5361 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5362   if (dest.is_old()) {
5363     return true;
5364   } else {
5365     return young_list()->survivor_length() < g1_policy()->max_survivor_regions();
5366   }
5367 }
5368 
5369 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5370   assert(FreeList_lock->owned_by_self(), "pre-condition");
5371 
5372   if (!has_more_regions(dest)) {
5373     return NULL;
5374   }
5375 
5376   const bool is_survivor = dest.is_young();
5377 
5378   HeapRegion* new_alloc_region = new_region(word_size,
5379                                             !is_survivor,
5380                                             true /* do_expand */);
5381   if (new_alloc_region != NULL) {
5382     // We really only need to do this for old regions given that we
5383     // should never scan survivors. But it doesn't hurt to do it
5384     // for survivors too.
5385     new_alloc_region->record_timestamp();
5386     if (is_survivor) {
5387       new_alloc_region->set_survivor();
5388       young_list()->add_survivor_region(new_alloc_region);
5389       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5390     } else {
5391       new_alloc_region->set_old();
5392       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5393     }
5394     _hr_printer.alloc(new_alloc_region);
5395     bool during_im = collector_state()->during_initial_mark_pause();
5396     new_alloc_region->note_start_of_copying(during_im);
5397     return new_alloc_region;
5398   }
5399   return NULL;
5400 }
5401 
5402 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5403                                              size_t allocated_bytes,
5404                                              InCSetState dest) {
5405   bool during_im = collector_state()->during_initial_mark_pause();
5406   alloc_region->note_end_of_copying(during_im);
5407   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5408   if (dest.is_old()) {
5409     _old_set.add(alloc_region);
5410   }
5411   _hr_printer.retire(alloc_region);
5412 }
5413 
5414 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5415   bool expanded = false;
5416   uint index = _hrm.find_highest_free(&expanded);
5417 
5418   if (index != G1_NO_HRM_INDEX) {
5419     if (expanded) {
5420       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5421                                 HeapRegion::GrainWords * HeapWordSize);
5422     }
5423     _hrm.allocate_free_regions_starting_at(index, 1);
5424     return region_at(index);
5425   }
5426   return NULL;
5427 }
5428 
5429 // Optimized nmethod scanning
5430 
5431 class RegisterNMethodOopClosure: public OopClosure {
5432   G1CollectedHeap* _g1h;
5433   nmethod* _nm;
5434 
5435   template <class T> void do_oop_work(T* p) {
5436     T heap_oop = oopDesc::load_heap_oop(p);
5437     if (!oopDesc::is_null(heap_oop)) {
5438       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5439       HeapRegion* hr = _g1h->heap_region_containing(obj);
5440       assert(!hr->is_continues_humongous(),
5441              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5442              " starting at " HR_FORMAT,
5443              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5444 
5445       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5446       hr->add_strong_code_root_locked(_nm);
5447     }
5448   }
5449 
5450 public:
5451   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5452     _g1h(g1h), _nm(nm) {}
5453 
5454   void do_oop(oop* p)       { do_oop_work(p); }
5455   void do_oop(narrowOop* p) { do_oop_work(p); }
5456 };
5457 
5458 class UnregisterNMethodOopClosure: public OopClosure {
5459   G1CollectedHeap* _g1h;
5460   nmethod* _nm;
5461 
5462   template <class T> void do_oop_work(T* p) {
5463     T heap_oop = oopDesc::load_heap_oop(p);
5464     if (!oopDesc::is_null(heap_oop)) {
5465       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5466       HeapRegion* hr = _g1h->heap_region_containing(obj);
5467       assert(!hr->is_continues_humongous(),
5468              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5469              " starting at " HR_FORMAT,
5470              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5471 
5472       hr->remove_strong_code_root(_nm);
5473     }
5474   }
5475 
5476 public:
5477   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5478     _g1h(g1h), _nm(nm) {}
5479 
5480   void do_oop(oop* p)       { do_oop_work(p); }
5481   void do_oop(narrowOop* p) { do_oop_work(p); }
5482 };
5483 
5484 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5485   CollectedHeap::register_nmethod(nm);
5486 
5487   guarantee(nm != NULL, "sanity");
5488   RegisterNMethodOopClosure reg_cl(this, nm);
5489   nm->oops_do(&reg_cl);
5490 }
5491 
5492 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5493   CollectedHeap::unregister_nmethod(nm);
5494 
5495   guarantee(nm != NULL, "sanity");
5496   UnregisterNMethodOopClosure reg_cl(this, nm);
5497   nm->oops_do(&reg_cl, true);
5498 }
5499 
5500 void G1CollectedHeap::purge_code_root_memory() {
5501   double purge_start = os::elapsedTime();
5502   G1CodeRootSet::purge();
5503   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5504   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5505 }
5506 
5507 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5508   G1CollectedHeap* _g1h;
5509 
5510 public:
5511   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5512     _g1h(g1h) {}
5513 
5514   void do_code_blob(CodeBlob* cb) {
5515     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5516     if (nm == NULL) {
5517       return;
5518     }
5519 
5520     if (ScavengeRootsInCode) {
5521       _g1h->register_nmethod(nm);
5522     }
5523   }
5524 };
5525 
5526 void G1CollectedHeap::rebuild_strong_code_roots() {
5527   RebuildStrongCodeRootClosure blob_cl(this);
5528   CodeCache::blobs_do(&blob_cl);
5529 }