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/g1HotCardCache.hpp"
  46 #include "gc/g1/g1MarkSweep.hpp"
  47 #include "gc/g1/g1OopClosures.inline.hpp"
  48 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  49 #include "gc/g1/g1Policy.hpp"
  50 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  51 #include "gc/g1/g1RemSet.inline.hpp"
  52 #include "gc/g1/g1RootClosures.hpp"
  53 #include "gc/g1/g1RootProcessor.hpp"
  54 #include "gc/g1/g1StringDedup.hpp"
  55 #include "gc/g1/g1YCTypes.hpp"
  56 #include "gc/g1/heapRegion.inline.hpp"
  57 #include "gc/g1/heapRegionRemSet.hpp"
  58 #include "gc/g1/heapRegionSet.inline.hpp"
  59 #include "gc/g1/suspendibleThreadSet.hpp"
  60 #include "gc/g1/vm_operations_g1.hpp"
  61 #include "gc/shared/gcHeapSummary.hpp"
  62 #include "gc/shared/gcId.hpp"
  63 #include "gc/shared/gcLocker.inline.hpp"
  64 #include "gc/shared/gcTimer.hpp"
  65 #include "gc/shared/gcTrace.hpp"
  66 #include "gc/shared/gcTraceTime.inline.hpp"
  67 #include "gc/shared/generationSpec.hpp"
  68 #include "gc/shared/isGCActiveMark.hpp"
  69 #include "gc/shared/preservedMarks.inline.hpp"
  70 #include "gc/shared/referenceProcessor.inline.hpp"
  71 #include "gc/shared/taskqueue.inline.hpp"
  72 #include "logging/log.hpp"
  73 #include "memory/allocation.hpp"
  74 #include "memory/iterator.hpp"
  75 #include "memory/resourceArea.hpp"
  76 #include "oops/oop.inline.hpp"
  77 #include "runtime/atomic.inline.hpp"
  78 #include "runtime/init.hpp"
  79 #include "runtime/orderAccess.inline.hpp"
  80 #include "runtime/vmThread.hpp"
  81 #include "utilities/globalDefinitions.hpp"
  82 #include "utilities/stack.inline.hpp"
  83 
  84 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  85 
  86 // INVARIANTS/NOTES
  87 //
  88 // All allocation activity covered by the G1CollectedHeap interface is
  89 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  90 // and allocate_new_tlab, which are the "entry" points to the
  91 // allocation code from the rest of the JVM.  (Note that this does not
  92 // apply to TLAB allocation, which is not part of this interface: it
  93 // is done by clients of this interface.)
  94 
  95 // Local to this file.
  96 
  97 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  98   bool _concurrent;
  99 public:
 100   RefineCardTableEntryClosure() : _concurrent(true) { }
 101 
 102   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 103     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, NULL);
 104     // This path is executed by the concurrent refine or mutator threads,
 105     // concurrently, and so we do not care if card_ptr contains references
 106     // that point into the collection set.
 107     assert(!oops_into_cset, "should be");
 108 
 109     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 110       // Caller will actually yield.
 111       return false;
 112     }
 113     // Otherwise, we finished successfully; return true.
 114     return true;
 115   }
 116 
 117   void set_concurrent(bool b) { _concurrent = b; }
 118 };
 119 
 120 
 121 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 122  private:
 123   size_t _num_dirtied;
 124   G1CollectedHeap* _g1h;
 125   G1SATBCardTableLoggingModRefBS* _g1_bs;
 126 
 127   HeapRegion* region_for_card(jbyte* card_ptr) const {
 128     return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
 129   }
 130 
 131   bool will_become_free(HeapRegion* hr) const {
 132     // A region will be freed by free_collection_set if the region is in the
 133     // collection set and has not had an evacuation failure.
 134     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 135   }
 136 
 137  public:
 138   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 139     _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
 140 
 141   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 142     HeapRegion* hr = region_for_card(card_ptr);
 143 
 144     // Should only dirty cards in regions that won't be freed.
 145     if (!will_become_free(hr)) {
 146       *card_ptr = CardTableModRefBS::dirty_card_val();
 147       _num_dirtied++;
 148     }
 149 
 150     return true;
 151   }
 152 
 153   size_t num_dirtied()   const { return _num_dirtied; }
 154 };
 155 
 156 
 157 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 158   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 159 }
 160 
 161 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 162   // The from card cache is not the memory that is actually committed. So we cannot
 163   // take advantage of the zero_filled parameter.
 164   reset_from_card_cache(start_idx, num_regions);
 165 }
 166 
 167 // Returns true if the reference points to an object that
 168 // can move in an incremental collection.
 169 bool G1CollectedHeap::is_scavengable(const void* p) {
 170   HeapRegion* hr = heap_region_containing(p);
 171   return !hr->is_pinned();
 172 }
 173 
 174 // Private methods.
 175 
 176 HeapRegion*
 177 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 178   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 179   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 180     if (!_secondary_free_list.is_empty()) {
 181       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 182                                       "secondary_free_list has %u entries",
 183                                       _secondary_free_list.length());
 184       // It looks as if there are free regions available on the
 185       // secondary_free_list. Let's move them to the free_list and try
 186       // again to allocate from it.
 187       append_secondary_free_list();
 188 
 189       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 190              "empty we should have moved at least one entry to the free_list");
 191       HeapRegion* res = _hrm.allocate_free_region(is_old);
 192       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 193                                       "allocated " HR_FORMAT " from secondary_free_list",
 194                                       HR_FORMAT_PARAMS(res));
 195       return res;
 196     }
 197 
 198     // Wait here until we get notified either when (a) there are no
 199     // more free regions coming or (b) some regions have been moved on
 200     // the secondary_free_list.
 201     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 202   }
 203 
 204   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 205                                   "could not allocate from secondary_free_list");
 206   return NULL;
 207 }
 208 
 209 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 210   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 211          "the only time we use this to allocate a humongous region is "
 212          "when we are allocating a single humongous region");
 213 
 214   HeapRegion* res;
 215   if (G1StressConcRegionFreeing) {
 216     if (!_secondary_free_list.is_empty()) {
 217       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 218                                       "forced to look at the secondary_free_list");
 219       res = new_region_try_secondary_free_list(is_old);
 220       if (res != NULL) {
 221         return res;
 222       }
 223     }
 224   }
 225 
 226   res = _hrm.allocate_free_region(is_old);
 227 
 228   if (res == NULL) {
 229     log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 230                                     "res == NULL, trying the secondary_free_list");
 231     res = new_region_try_secondary_free_list(is_old);
 232   }
 233   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 234     // Currently, only attempts to allocate GC alloc regions set
 235     // do_expand to true. So, we should only reach here during a
 236     // safepoint. If this assumption changes we might have to
 237     // reconsider the use of _expand_heap_after_alloc_failure.
 238     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 239 
 240     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 241                               word_size * HeapWordSize);
 242 
 243     if (expand(word_size * HeapWordSize)) {
 244       // Given that expand() succeeded in expanding the heap, and we
 245       // always expand the heap by an amount aligned to the heap
 246       // region size, the free list should in theory not be empty.
 247       // In either case allocate_free_region() will check for NULL.
 248       res = _hrm.allocate_free_region(is_old);
 249     } else {
 250       _expand_heap_after_alloc_failure = false;
 251     }
 252   }
 253   return res;
 254 }
 255 
 256 HeapWord*
 257 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 258                                                            uint num_regions,
 259                                                            size_t word_size,
 260                                                            AllocationContext_t context) {
 261   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 262   assert(is_humongous(word_size), "word_size should be humongous");
 263   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 264 
 265   // Index of last region in the series.
 266   uint last = first + num_regions - 1;
 267 
 268   // We need to initialize the region(s) we just discovered. This is
 269   // a bit tricky given that it can happen concurrently with
 270   // refinement threads refining cards on these regions and
 271   // potentially wanting to refine the BOT as they are scanning
 272   // those cards (this can happen shortly after a cleanup; see CR
 273   // 6991377). So we have to set up the region(s) carefully and in
 274   // a specific order.
 275 
 276   // The word size sum of all the regions we will allocate.
 277   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 278   assert(word_size <= word_size_sum, "sanity");
 279 
 280   // This will be the "starts humongous" region.
 281   HeapRegion* first_hr = region_at(first);
 282   // The header of the new object will be placed at the bottom of
 283   // the first region.
 284   HeapWord* new_obj = first_hr->bottom();
 285   // This will be the new top of the new object.
 286   HeapWord* obj_top = new_obj + word_size;
 287 
 288   // First, we need to zero the header of the space that we will be
 289   // allocating. When we update top further down, some refinement
 290   // threads might try to scan the region. By zeroing the header we
 291   // ensure that any thread that will try to scan the region will
 292   // come across the zero klass word and bail out.
 293   //
 294   // NOTE: It would not have been correct to have used
 295   // CollectedHeap::fill_with_object() and make the space look like
 296   // an int array. The thread that is doing the allocation will
 297   // later update the object header to a potentially different array
 298   // type and, for a very short period of time, the klass and length
 299   // fields will be inconsistent. This could cause a refinement
 300   // thread to calculate the object size incorrectly.
 301   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 302 
 303   // How many words we use for filler objects.
 304   size_t word_fill_size = word_size_sum - word_size;
 305 
 306   // How many words memory we "waste" which cannot hold a filler object.
 307   size_t words_not_fillable = 0;
 308 
 309   if (word_fill_size >= min_fill_size()) {
 310     fill_with_objects(obj_top, word_fill_size);
 311   } else if (word_fill_size > 0) {
 312     // We have space to fill, but we cannot fit an object there.
 313     words_not_fillable = word_fill_size;
 314     word_fill_size = 0;
 315   }
 316 
 317   // We will set up the first region as "starts humongous". This
 318   // will also update the BOT covering all the regions to reflect
 319   // that there is a single object that starts at the bottom of the
 320   // first region.
 321   first_hr->set_starts_humongous(obj_top, word_fill_size);
 322   first_hr->set_allocation_context(context);
 323   // Then, if there are any, we will set up the "continues
 324   // humongous" regions.
 325   HeapRegion* hr = NULL;
 326   for (uint i = first + 1; i <= last; ++i) {
 327     hr = region_at(i);
 328     hr->set_continues_humongous(first_hr);
 329     hr->set_allocation_context(context);
 330   }
 331 
 332   // Up to this point no concurrent thread would have been able to
 333   // do any scanning on any region in this series. All the top
 334   // fields still point to bottom, so the intersection between
 335   // [bottom,top] and [card_start,card_end] will be empty. Before we
 336   // update the top fields, we'll do a storestore to make sure that
 337   // no thread sees the update to top before the zeroing of the
 338   // object header and the BOT initialization.
 339   OrderAccess::storestore();
 340 
 341   // Now, we will update the top fields of the "continues humongous"
 342   // regions except the last one.
 343   for (uint i = first; i < last; ++i) {
 344     hr = region_at(i);
 345     hr->set_top(hr->end());
 346   }
 347 
 348   hr = region_at(last);
 349   // If we cannot fit a filler object, we must set top to the end
 350   // of the humongous object, otherwise we cannot iterate the heap
 351   // and the BOT will not be complete.
 352   hr->set_top(hr->end() - words_not_fillable);
 353 
 354   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 355          "obj_top should be in last region");
 356 
 357   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 358 
 359   assert(words_not_fillable == 0 ||
 360          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 361          "Miscalculation in humongous allocation");
 362 
 363   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 364 
 365   for (uint i = first; i <= last; ++i) {
 366     hr = region_at(i);
 367     _humongous_set.add(hr);
 368     _hr_printer.alloc(hr);
 369   }
 370 
 371   return new_obj;
 372 }
 373 
 374 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 375   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 376   return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 377 }
 378 
 379 // If could fit into free regions w/o expansion, try.
 380 // Otherwise, if can expand, do so.
 381 // Otherwise, if using ex regions might help, try with ex given back.
 382 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 383   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 384 
 385   _verifier->verify_region_sets_optional();
 386 
 387   uint first = G1_NO_HRM_INDEX;
 388   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 389 
 390   if (obj_regions == 1) {
 391     // Only one region to allocate, try to use a fast path by directly allocating
 392     // from the free lists. Do not try to expand here, we will potentially do that
 393     // later.
 394     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 395     if (hr != NULL) {
 396       first = hr->hrm_index();
 397     }
 398   } else {
 399     // We can't allocate humongous regions spanning more than one region while
 400     // cleanupComplete() is running, since some of the regions we find to be
 401     // empty might not yet be added to the free list. It is not straightforward
 402     // to know in which list they are on so that we can remove them. We only
 403     // need to do this if we need to allocate more than one region to satisfy the
 404     // current humongous allocation request. If we are only allocating one region
 405     // we use the one-region region allocation code (see above), that already
 406     // potentially waits for regions from the secondary free list.
 407     wait_while_free_regions_coming();
 408     append_secondary_free_list_if_not_empty_with_lock();
 409 
 410     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 411     // are lucky enough to find some.
 412     first = _hrm.find_contiguous_only_empty(obj_regions);
 413     if (first != G1_NO_HRM_INDEX) {
 414       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 415     }
 416   }
 417 
 418   if (first == G1_NO_HRM_INDEX) {
 419     // Policy: We could not find enough regions for the humongous object in the
 420     // free list. Look through the heap to find a mix of free and uncommitted regions.
 421     // If so, try expansion.
 422     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 423     if (first != G1_NO_HRM_INDEX) {
 424       // We found something. Make sure these regions are committed, i.e. expand
 425       // the heap. Alternatively we could do a defragmentation GC.
 426       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 427                                     word_size * HeapWordSize);
 428 
 429 
 430       _hrm.expand_at(first, obj_regions);
 431       g1_policy()->record_new_heap_size(num_regions());
 432 
 433 #ifdef ASSERT
 434       for (uint i = first; i < first + obj_regions; ++i) {
 435         HeapRegion* hr = region_at(i);
 436         assert(hr->is_free(), "sanity");
 437         assert(hr->is_empty(), "sanity");
 438         assert(is_on_master_free_list(hr), "sanity");
 439       }
 440 #endif
 441       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 442     } else {
 443       // Policy: Potentially trigger a defragmentation GC.
 444     }
 445   }
 446 
 447   HeapWord* result = NULL;
 448   if (first != G1_NO_HRM_INDEX) {
 449     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 450                                                        word_size, context);
 451     assert(result != NULL, "it should always return a valid result");
 452 
 453     // A successful humongous object allocation changes the used space
 454     // information of the old generation so we need to recalculate the
 455     // sizes and update the jstat counters here.
 456     g1mm()->update_sizes();
 457   }
 458 
 459   _verifier->verify_region_sets_optional();
 460 
 461   return result;
 462 }
 463 
 464 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 465   assert_heap_not_locked_and_not_at_safepoint();
 466   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 467 
 468   uint dummy_gc_count_before;
 469   uint dummy_gclocker_retry_count = 0;
 470   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 471 }
 472 
 473 HeapWord*
 474 G1CollectedHeap::mem_allocate(size_t word_size,
 475                               bool*  gc_overhead_limit_was_exceeded) {
 476   assert_heap_not_locked_and_not_at_safepoint();
 477 
 478   // Loop until the allocation is satisfied, or unsatisfied after GC.
 479   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 480     uint gc_count_before;
 481 
 482     HeapWord* result = NULL;
 483     if (!is_humongous(word_size)) {
 484       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 485     } else {
 486       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 487     }
 488     if (result != NULL) {
 489       return result;
 490     }
 491 
 492     // Create the garbage collection operation...
 493     VM_G1CollectForAllocation op(gc_count_before, word_size);
 494     op.set_allocation_context(AllocationContext::current());
 495 
 496     // ...and get the VM thread to execute it.
 497     VMThread::execute(&op);
 498 
 499     if (op.prologue_succeeded() && op.pause_succeeded()) {
 500       // If the operation was successful we'll return the result even
 501       // if it is NULL. If the allocation attempt failed immediately
 502       // after a Full GC, it's unlikely we'll be able to allocate now.
 503       HeapWord* result = op.result();
 504       if (result != NULL && !is_humongous(word_size)) {
 505         // Allocations that take place on VM operations do not do any
 506         // card dirtying and we have to do it here. We only have to do
 507         // this for non-humongous allocations, though.
 508         dirty_young_block(result, word_size);
 509       }
 510       return result;
 511     } else {
 512       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 513         return NULL;
 514       }
 515       assert(op.result() == NULL,
 516              "the result should be NULL if the VM op did not succeed");
 517     }
 518 
 519     // Give a warning if we seem to be looping forever.
 520     if ((QueuedAllocationWarningCount > 0) &&
 521         (try_count % QueuedAllocationWarningCount == 0)) {
 522       log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
 523     }
 524   }
 525 
 526   ShouldNotReachHere();
 527   return NULL;
 528 }
 529 
 530 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 531                                                    AllocationContext_t context,
 532                                                    uint* gc_count_before_ret,
 533                                                    uint* gclocker_retry_count_ret) {
 534   // Make sure you read the note in attempt_allocation_humongous().
 535 
 536   assert_heap_not_locked_and_not_at_safepoint();
 537   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 538          "be called for humongous allocation requests");
 539 
 540   // We should only get here after the first-level allocation attempt
 541   // (attempt_allocation()) failed to allocate.
 542 
 543   // We will loop until a) we manage to successfully perform the
 544   // allocation or b) we successfully schedule a collection which
 545   // fails to perform the allocation. b) is the only case when we'll
 546   // return NULL.
 547   HeapWord* result = NULL;
 548   for (int try_count = 1; /* we'll return */; try_count += 1) {
 549     bool should_try_gc;
 550     uint gc_count_before;
 551 
 552     {
 553       MutexLockerEx x(Heap_lock);
 554       result = _allocator->attempt_allocation_locked(word_size, context);
 555       if (result != NULL) {
 556         return result;
 557       }
 558 
 559       if (GCLocker::is_active_and_needs_gc()) {
 560         if (g1_policy()->can_expand_young_list()) {
 561           // No need for an ergo verbose message here,
 562           // can_expand_young_list() does this when it returns true.
 563           result = _allocator->attempt_allocation_force(word_size, context);
 564           if (result != NULL) {
 565             return result;
 566           }
 567         }
 568         should_try_gc = false;
 569       } else {
 570         // The GCLocker may not be active but the GCLocker initiated
 571         // GC may not yet have been performed (GCLocker::needs_gc()
 572         // returns true). In this case we do not try this GC and
 573         // wait until the GCLocker initiated GC is performed, and
 574         // then retry the allocation.
 575         if (GCLocker::needs_gc()) {
 576           should_try_gc = false;
 577         } else {
 578           // Read the GC count while still holding the Heap_lock.
 579           gc_count_before = total_collections();
 580           should_try_gc = true;
 581         }
 582       }
 583     }
 584 
 585     if (should_try_gc) {
 586       bool succeeded;
 587       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 588                                    GCCause::_g1_inc_collection_pause);
 589       if (result != NULL) {
 590         assert(succeeded, "only way to get back a non-NULL result");
 591         return result;
 592       }
 593 
 594       if (succeeded) {
 595         // If we get here we successfully scheduled a collection which
 596         // failed to allocate. No point in trying to allocate
 597         // further. We'll just return NULL.
 598         MutexLockerEx x(Heap_lock);
 599         *gc_count_before_ret = total_collections();
 600         return NULL;
 601       }
 602     } else {
 603       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 604         MutexLockerEx x(Heap_lock);
 605         *gc_count_before_ret = total_collections();
 606         return NULL;
 607       }
 608       // The GCLocker is either active or the GCLocker initiated
 609       // GC has not yet been performed. Stall until it is and
 610       // then retry the allocation.
 611       GCLocker::stall_until_clear();
 612       (*gclocker_retry_count_ret) += 1;
 613     }
 614 
 615     // We can reach here if we were unsuccessful in scheduling a
 616     // collection (because another thread beat us to it) or if we were
 617     // stalled due to the GC locker. In either can we should retry the
 618     // allocation attempt in case another thread successfully
 619     // performed a collection and reclaimed enough space. We do the
 620     // first attempt (without holding the Heap_lock) here and the
 621     // follow-on attempt will be at the start of the next loop
 622     // iteration (after taking the Heap_lock).
 623     result = _allocator->attempt_allocation(word_size, context);
 624     if (result != NULL) {
 625       return result;
 626     }
 627 
 628     // Give a warning if we seem to be looping forever.
 629     if ((QueuedAllocationWarningCount > 0) &&
 630         (try_count % QueuedAllocationWarningCount == 0)) {
 631       log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
 632                       "retries %d times", try_count);
 633     }
 634   }
 635 
 636   ShouldNotReachHere();
 637   return NULL;
 638 }
 639 
 640 void G1CollectedHeap::begin_archive_alloc_range() {
 641   assert_at_safepoint(true /* should_be_vm_thread */);
 642   if (_archive_allocator == NULL) {
 643     _archive_allocator = G1ArchiveAllocator::create_allocator(this);
 644   }
 645 }
 646 
 647 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 648   // Allocations in archive regions cannot be of a size that would be considered
 649   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 650   // may be different at archive-restore time.
 651   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 652 }
 653 
 654 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 655   assert_at_safepoint(true /* should_be_vm_thread */);
 656   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 657   if (is_archive_alloc_too_large(word_size)) {
 658     return NULL;
 659   }
 660   return _archive_allocator->archive_mem_allocate(word_size);
 661 }
 662 
 663 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 664                                               size_t end_alignment_in_bytes) {
 665   assert_at_safepoint(true /* should_be_vm_thread */);
 666   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 667 
 668   // Call complete_archive to do the real work, filling in the MemRegion
 669   // array with the archive regions.
 670   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 671   delete _archive_allocator;
 672   _archive_allocator = NULL;
 673 }
 674 
 675 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 676   assert(ranges != NULL, "MemRegion array NULL");
 677   assert(count != 0, "No MemRegions provided");
 678   MemRegion reserved = _hrm.reserved();
 679   for (size_t i = 0; i < count; i++) {
 680     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 681       return false;
 682     }
 683   }
 684   return true;
 685 }
 686 
 687 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
 688   assert(!is_init_completed(), "Expect to be called at JVM init time");
 689   assert(ranges != NULL, "MemRegion array NULL");
 690   assert(count != 0, "No MemRegions provided");
 691   MutexLockerEx x(Heap_lock);
 692 
 693   MemRegion reserved = _hrm.reserved();
 694   HeapWord* prev_last_addr = NULL;
 695   HeapRegion* prev_last_region = NULL;
 696 
 697   // Temporarily disable pretouching of heap pages. This interface is used
 698   // when mmap'ing archived heap data in, so pre-touching is wasted.
 699   FlagSetting fs(AlwaysPreTouch, false);
 700 
 701   // Enable archive object checking in G1MarkSweep. We have to let it know
 702   // about each archive range, so that objects in those ranges aren't marked.
 703   G1MarkSweep::enable_archive_object_check();
 704 
 705   // For each specified MemRegion range, allocate the corresponding G1
 706   // regions and mark them as archive regions. We expect the ranges in
 707   // ascending starting address order, without overlap.
 708   for (size_t i = 0; i < count; i++) {
 709     MemRegion curr_range = ranges[i];
 710     HeapWord* start_address = curr_range.start();
 711     size_t word_size = curr_range.word_size();
 712     HeapWord* last_address = curr_range.last();
 713     size_t commits = 0;
 714 
 715     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 716               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 717               p2i(start_address), p2i(last_address));
 718     guarantee(start_address > prev_last_addr,
 719               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 720               p2i(start_address), p2i(prev_last_addr));
 721     prev_last_addr = last_address;
 722 
 723     // Check for ranges that start in the same G1 region in which the previous
 724     // range ended, and adjust the start address so we don't try to allocate
 725     // the same region again. If the current range is entirely within that
 726     // region, skip it, just adjusting the recorded top.
 727     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 728     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 729       start_address = start_region->end();
 730       if (start_address > last_address) {
 731         increase_used(word_size * HeapWordSize);
 732         start_region->set_top(last_address + 1);
 733         continue;
 734       }
 735       start_region->set_top(start_address);
 736       curr_range = MemRegion(start_address, last_address + 1);
 737       start_region = _hrm.addr_to_region(start_address);
 738     }
 739 
 740     // Perform the actual region allocation, exiting if it fails.
 741     // Then note how much new space we have allocated.
 742     if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
 743       return false;
 744     }
 745     increase_used(word_size * HeapWordSize);
 746     if (commits != 0) {
 747       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 748                                 HeapRegion::GrainWords * HeapWordSize * commits);
 749 
 750     }
 751 
 752     // Mark each G1 region touched by the range as archive, add it to the old set,
 753     // and set the allocation context and top.
 754     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 755     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 756     prev_last_region = last_region;
 757 
 758     while (curr_region != NULL) {
 759       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 760              "Region already in use (index %u)", curr_region->hrm_index());
 761       curr_region->set_allocation_context(AllocationContext::system());
 762       curr_region->set_archive();
 763       _hr_printer.alloc(curr_region);
 764       _old_set.add(curr_region);
 765       if (curr_region != last_region) {
 766         curr_region->set_top(curr_region->end());
 767         curr_region = _hrm.next_region_in_heap(curr_region);
 768       } else {
 769         curr_region->set_top(last_address + 1);
 770         curr_region = NULL;
 771       }
 772     }
 773 
 774     // Notify mark-sweep of the archive range.
 775     G1MarkSweep::set_range_archive(curr_range, true);
 776   }
 777   return true;
 778 }
 779 
 780 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 781   assert(!is_init_completed(), "Expect to be called at JVM init time");
 782   assert(ranges != NULL, "MemRegion array NULL");
 783   assert(count != 0, "No MemRegions provided");
 784   MemRegion reserved = _hrm.reserved();
 785   HeapWord *prev_last_addr = NULL;
 786   HeapRegion* prev_last_region = NULL;
 787 
 788   // For each MemRegion, create filler objects, if needed, in the G1 regions
 789   // that contain the address range. The address range actually within the
 790   // MemRegion will not be modified. That is assumed to have been initialized
 791   // elsewhere, probably via an mmap of archived heap data.
 792   MutexLockerEx x(Heap_lock);
 793   for (size_t i = 0; i < count; i++) {
 794     HeapWord* start_address = ranges[i].start();
 795     HeapWord* last_address = ranges[i].last();
 796 
 797     assert(reserved.contains(start_address) && reserved.contains(last_address),
 798            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 799            p2i(start_address), p2i(last_address));
 800     assert(start_address > prev_last_addr,
 801            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 802            p2i(start_address), p2i(prev_last_addr));
 803 
 804     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 805     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 806     HeapWord* bottom_address = start_region->bottom();
 807 
 808     // Check for a range beginning in the same region in which the
 809     // previous one ended.
 810     if (start_region == prev_last_region) {
 811       bottom_address = prev_last_addr + 1;
 812     }
 813 
 814     // Verify that the regions were all marked as archive regions by
 815     // alloc_archive_regions.
 816     HeapRegion* curr_region = start_region;
 817     while (curr_region != NULL) {
 818       guarantee(curr_region->is_archive(),
 819                 "Expected archive region at index %u", curr_region->hrm_index());
 820       if (curr_region != last_region) {
 821         curr_region = _hrm.next_region_in_heap(curr_region);
 822       } else {
 823         curr_region = NULL;
 824       }
 825     }
 826 
 827     prev_last_addr = last_address;
 828     prev_last_region = last_region;
 829 
 830     // Fill the memory below the allocated range with dummy object(s),
 831     // if the region bottom does not match the range start, or if the previous
 832     // range ended within the same G1 region, and there is a gap.
 833     if (start_address != bottom_address) {
 834       size_t fill_size = pointer_delta(start_address, bottom_address);
 835       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 836       increase_used(fill_size * HeapWordSize);
 837     }
 838   }
 839 }
 840 
 841 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
 842                                                      uint* gc_count_before_ret,
 843                                                      uint* gclocker_retry_count_ret) {
 844   assert_heap_not_locked_and_not_at_safepoint();
 845   assert(!is_humongous(word_size), "attempt_allocation() should not "
 846          "be called for humongous allocation requests");
 847 
 848   AllocationContext_t context = AllocationContext::current();
 849   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 850 
 851   if (result == NULL) {
 852     result = attempt_allocation_slow(word_size,
 853                                      context,
 854                                      gc_count_before_ret,
 855                                      gclocker_retry_count_ret);
 856   }
 857   assert_heap_not_locked();
 858   if (result != NULL) {
 859     dirty_young_block(result, word_size);
 860   }
 861   return result;
 862 }
 863 
 864 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 865   assert(!is_init_completed(), "Expect to be called at JVM init time");
 866   assert(ranges != NULL, "MemRegion array NULL");
 867   assert(count != 0, "No MemRegions provided");
 868   MemRegion reserved = _hrm.reserved();
 869   HeapWord* prev_last_addr = NULL;
 870   HeapRegion* prev_last_region = NULL;
 871   size_t size_used = 0;
 872   size_t uncommitted_regions = 0;
 873 
 874   // For each Memregion, free the G1 regions that constitute it, and
 875   // notify mark-sweep that the range is no longer to be considered 'archive.'
 876   MutexLockerEx x(Heap_lock);
 877   for (size_t i = 0; i < count; i++) {
 878     HeapWord* start_address = ranges[i].start();
 879     HeapWord* last_address = ranges[i].last();
 880 
 881     assert(reserved.contains(start_address) && reserved.contains(last_address),
 882            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 883            p2i(start_address), p2i(last_address));
 884     assert(start_address > prev_last_addr,
 885            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 886            p2i(start_address), p2i(prev_last_addr));
 887     size_used += ranges[i].byte_size();
 888     prev_last_addr = last_address;
 889 
 890     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 891     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 892 
 893     // Check for ranges that start in the same G1 region in which the previous
 894     // range ended, and adjust the start address so we don't try to free
 895     // the same region again. If the current range is entirely within that
 896     // region, skip it.
 897     if (start_region == prev_last_region) {
 898       start_address = start_region->end();
 899       if (start_address > last_address) {
 900         continue;
 901       }
 902       start_region = _hrm.addr_to_region(start_address);
 903     }
 904     prev_last_region = last_region;
 905 
 906     // After verifying that each region was marked as an archive region by
 907     // alloc_archive_regions, set it free and empty and uncommit it.
 908     HeapRegion* curr_region = start_region;
 909     while (curr_region != NULL) {
 910       guarantee(curr_region->is_archive(),
 911                 "Expected archive region at index %u", curr_region->hrm_index());
 912       uint curr_index = curr_region->hrm_index();
 913       _old_set.remove(curr_region);
 914       curr_region->set_free();
 915       curr_region->set_top(curr_region->bottom());
 916       if (curr_region != last_region) {
 917         curr_region = _hrm.next_region_in_heap(curr_region);
 918       } else {
 919         curr_region = NULL;
 920       }
 921       _hrm.shrink_at(curr_index, 1);
 922       uncommitted_regions++;
 923     }
 924 
 925     // Notify mark-sweep that this is no longer an archive range.
 926     G1MarkSweep::set_range_archive(ranges[i], false);
 927   }
 928 
 929   if (uncommitted_regions != 0) {
 930     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 931                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 932   }
 933   decrease_used(size_used);
 934 }
 935 
 936 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 937                                                         uint* gc_count_before_ret,
 938                                                         uint* gclocker_retry_count_ret) {
 939   // The structure of this method has a lot of similarities to
 940   // attempt_allocation_slow(). The reason these two were not merged
 941   // into a single one is that such a method would require several "if
 942   // allocation is not humongous do this, otherwise do that"
 943   // conditional paths which would obscure its flow. In fact, an early
 944   // version of this code did use a unified method which was harder to
 945   // follow and, as a result, it had subtle bugs that were hard to
 946   // track down. So keeping these two methods separate allows each to
 947   // be more readable. It will be good to keep these two in sync as
 948   // much as possible.
 949 
 950   assert_heap_not_locked_and_not_at_safepoint();
 951   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 952          "should only be called for humongous allocations");
 953 
 954   // Humongous objects can exhaust the heap quickly, so we should check if we
 955   // need to start a marking cycle at each humongous object allocation. We do
 956   // the check before we do the actual allocation. The reason for doing it
 957   // before the allocation is that we avoid having to keep track of the newly
 958   // allocated memory while we do a GC.
 959   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 960                                            word_size)) {
 961     collect(GCCause::_g1_humongous_allocation);
 962   }
 963 
 964   // We will loop until a) we manage to successfully perform the
 965   // allocation or b) we successfully schedule a collection which
 966   // fails to perform the allocation. b) is the only case when we'll
 967   // return NULL.
 968   HeapWord* result = NULL;
 969   for (int try_count = 1; /* we'll return */; try_count += 1) {
 970     bool should_try_gc;
 971     uint gc_count_before;
 972 
 973     {
 974       MutexLockerEx x(Heap_lock);
 975 
 976       // Given that humongous objects are not allocated in young
 977       // regions, we'll first try to do the allocation without doing a
 978       // collection hoping that there's enough space in the heap.
 979       result = humongous_obj_allocate(word_size, AllocationContext::current());
 980       if (result != NULL) {
 981         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 982         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 983         return result;
 984       }
 985 
 986       if (GCLocker::is_active_and_needs_gc()) {
 987         should_try_gc = false;
 988       } else {
 989          // The GCLocker may not be active but the GCLocker initiated
 990         // GC may not yet have been performed (GCLocker::needs_gc()
 991         // returns true). In this case we do not try this GC and
 992         // wait until the GCLocker initiated GC is performed, and
 993         // then retry the allocation.
 994         if (GCLocker::needs_gc()) {
 995           should_try_gc = false;
 996         } else {
 997           // Read the GC count while still holding the Heap_lock.
 998           gc_count_before = total_collections();
 999           should_try_gc = true;
1000         }
1001       }
1002     }
1003 
1004     if (should_try_gc) {
1005       // If we failed to allocate the humongous object, we should try to
1006       // do a collection pause (if we're allowed) in case it reclaims
1007       // enough space for the allocation to succeed after the pause.
1008 
1009       bool succeeded;
1010       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1011                                    GCCause::_g1_humongous_allocation);
1012       if (result != NULL) {
1013         assert(succeeded, "only way to get back a non-NULL result");
1014         return result;
1015       }
1016 
1017       if (succeeded) {
1018         // If we get here we successfully scheduled a collection which
1019         // failed to allocate. No point in trying to allocate
1020         // further. We'll just return NULL.
1021         MutexLockerEx x(Heap_lock);
1022         *gc_count_before_ret = total_collections();
1023         return NULL;
1024       }
1025     } else {
1026       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1027         MutexLockerEx x(Heap_lock);
1028         *gc_count_before_ret = total_collections();
1029         return NULL;
1030       }
1031       // The GCLocker is either active or the GCLocker initiated
1032       // GC has not yet been performed. Stall until it is and
1033       // then retry the allocation.
1034       GCLocker::stall_until_clear();
1035       (*gclocker_retry_count_ret) += 1;
1036     }
1037 
1038     // We can reach here if we were unsuccessful in scheduling a
1039     // collection (because another thread beat us to it) or if we were
1040     // stalled due to the GC locker. In either can we should retry the
1041     // allocation attempt in case another thread successfully
1042     // performed a collection and reclaimed enough space.  Give a
1043     // warning if we seem to be looping forever.
1044 
1045     if ((QueuedAllocationWarningCount > 0) &&
1046         (try_count % QueuedAllocationWarningCount == 0)) {
1047       log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1048                       "retries %d times", try_count);
1049     }
1050   }
1051 
1052   ShouldNotReachHere();
1053   return NULL;
1054 }
1055 
1056 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1057                                                            AllocationContext_t context,
1058                                                            bool expect_null_mutator_alloc_region) {
1059   assert_at_safepoint(true /* should_be_vm_thread */);
1060   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1061          "the current alloc region was unexpectedly found to be non-NULL");
1062 
1063   if (!is_humongous(word_size)) {
1064     return _allocator->attempt_allocation_locked(word_size, context);
1065   } else {
1066     HeapWord* result = humongous_obj_allocate(word_size, context);
1067     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1068       collector_state()->set_initiate_conc_mark_if_possible(true);
1069     }
1070     return result;
1071   }
1072 
1073   ShouldNotReachHere();
1074 }
1075 
1076 class PostMCRemSetClearClosure: public HeapRegionClosure {
1077   G1CollectedHeap* _g1h;
1078   ModRefBarrierSet* _mr_bs;
1079 public:
1080   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1081     _g1h(g1h), _mr_bs(mr_bs) {}
1082 
1083   bool doHeapRegion(HeapRegion* r) {
1084     HeapRegionRemSet* hrrs = r->rem_set();
1085 
1086     _g1h->reset_gc_time_stamps(r);
1087 
1088     if (r->is_continues_humongous()) {
1089       // We'll assert that the strong code root list and RSet is empty
1090       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1091       assert(hrrs->occupied() == 0, "RSet should be empty");
1092     } else {
1093       hrrs->clear();
1094     }
1095     // You might think here that we could clear just the cards
1096     // corresponding to the used region.  But no: if we leave a dirty card
1097     // in a region we might allocate into, then it would prevent that card
1098     // from being enqueued, and cause it to be missed.
1099     // Re: the performance cost: we shouldn't be doing full GC anyway!
1100     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1101 
1102     return false;
1103   }
1104 };
1105 
1106 void G1CollectedHeap::clear_rsets_post_compaction() {
1107   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1108   heap_region_iterate(&rs_clear);
1109 }
1110 
1111 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1112   G1CollectedHeap*   _g1h;
1113   UpdateRSOopClosure _cl;
1114 public:
1115   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1116     _cl(g1->g1_rem_set(), worker_i),
1117     _g1h(g1)
1118   { }
1119 
1120   bool doHeapRegion(HeapRegion* r) {
1121     if (!r->is_continues_humongous()) {
1122       _cl.set_from(r);
1123       r->oop_iterate(&_cl);
1124     }
1125     return false;
1126   }
1127 };
1128 
1129 class ParRebuildRSTask: public AbstractGangTask {
1130   G1CollectedHeap* _g1;
1131   HeapRegionClaimer _hrclaimer;
1132 
1133 public:
1134   ParRebuildRSTask(G1CollectedHeap* g1) :
1135       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1136 
1137   void work(uint worker_id) {
1138     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1139     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1140   }
1141 };
1142 
1143 class PostCompactionPrinterClosure: public HeapRegionClosure {
1144 private:
1145   G1HRPrinter* _hr_printer;
1146 public:
1147   bool doHeapRegion(HeapRegion* hr) {
1148     assert(!hr->is_young(), "not expecting to find young regions");
1149     _hr_printer->post_compaction(hr);
1150     return false;
1151   }
1152 
1153   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1154     : _hr_printer(hr_printer) { }
1155 };
1156 
1157 void G1CollectedHeap::print_hrm_post_compaction() {
1158   if (_hr_printer.is_active()) {
1159     PostCompactionPrinterClosure cl(hr_printer());
1160     heap_region_iterate(&cl);
1161   }
1162 
1163 }
1164 
1165 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1166                                          bool clear_all_soft_refs) {
1167   assert_at_safepoint(true /* should_be_vm_thread */);
1168 
1169   if (GCLocker::check_active_before_gc()) {
1170     return false;
1171   }
1172 
1173   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1174   gc_timer->register_gc_start();
1175 
1176   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1177   GCIdMark gc_id_mark;
1178   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1179 
1180   SvcGCMarker sgcm(SvcGCMarker::FULL);
1181   ResourceMark rm;
1182 
1183   print_heap_before_gc();
1184   print_heap_regions();
1185   trace_heap_before_gc(gc_tracer);
1186 
1187   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1188 
1189   _verifier->verify_region_sets_optional();
1190 
1191   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1192                            collector_policy()->should_clear_all_soft_refs();
1193 
1194   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1195 
1196   {
1197     IsGCActiveMark x;
1198 
1199     // Timing
1200     assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1201     GCTraceCPUTime tcpu;
1202 
1203     {
1204       GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1205       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1206       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1207 
1208       G1HeapTransition heap_transition(this);
1209       g1_policy()->record_full_collection_start();
1210 
1211       // Note: When we have a more flexible GC logging framework that
1212       // allows us to add optional attributes to a GC log record we
1213       // could consider timing and reporting how long we wait in the
1214       // following two methods.
1215       wait_while_free_regions_coming();
1216       // If we start the compaction before the CM threads finish
1217       // scanning the root regions we might trip them over as we'll
1218       // be moving objects / updating references. So let's wait until
1219       // they are done. By telling them to abort, they should complete
1220       // early.
1221       _cm->root_regions()->abort();
1222       _cm->root_regions()->wait_until_scan_finished();
1223       append_secondary_free_list_if_not_empty_with_lock();
1224 
1225       gc_prologue(true);
1226       increment_total_collections(true /* full gc */);
1227       increment_old_marking_cycles_started();
1228 
1229       assert(used() == recalculate_used(), "Should be equal");
1230 
1231       _verifier->verify_before_gc();
1232 
1233       _verifier->check_bitmaps("Full GC Start");
1234       pre_full_gc_dump(gc_timer);
1235 
1236 #if defined(COMPILER2) || INCLUDE_JVMCI
1237       DerivedPointerTable::clear();
1238 #endif
1239 
1240       // Disable discovery and empty the discovered lists
1241       // for the CM ref processor.
1242       ref_processor_cm()->disable_discovery();
1243       ref_processor_cm()->abandon_partial_discovery();
1244       ref_processor_cm()->verify_no_references_recorded();
1245 
1246       // Abandon current iterations of concurrent marking and concurrent
1247       // refinement, if any are in progress.
1248       concurrent_mark()->abort();
1249 
1250       // Make sure we'll choose a new allocation region afterwards.
1251       _allocator->release_mutator_alloc_region();
1252       _allocator->abandon_gc_alloc_regions();
1253       g1_rem_set()->cleanupHRRS();
1254 
1255       // We may have added regions to the current incremental collection
1256       // set between the last GC or pause and now. We need to clear the
1257       // incremental collection set and then start rebuilding it afresh
1258       // after this full GC.
1259       abandon_collection_set(collection_set()->inc_head());
1260       collection_set()->clear_incremental();
1261       collection_set()->stop_incremental_building();
1262 
1263       tear_down_region_sets(false /* free_list_only */);
1264       collector_state()->set_gcs_are_young(true);
1265 
1266       // See the comments in g1CollectedHeap.hpp and
1267       // G1CollectedHeap::ref_processing_init() about
1268       // how reference processing currently works in G1.
1269 
1270       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1271       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1272 
1273       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1274       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1275 
1276       ref_processor_stw()->enable_discovery();
1277       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1278 
1279       // Do collection work
1280       {
1281         HandleMark hm;  // Discard invalid handles created during gc
1282         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1283       }
1284 
1285       assert(num_free_regions() == 0, "we should not have added any free regions");
1286       rebuild_region_sets(false /* free_list_only */);
1287 
1288       // Enqueue any discovered reference objects that have
1289       // not been removed from the discovered lists.
1290       ref_processor_stw()->enqueue_discovered_references();
1291 
1292 #if defined(COMPILER2) || INCLUDE_JVMCI
1293       DerivedPointerTable::update_pointers();
1294 #endif
1295 
1296       MemoryService::track_memory_usage();
1297 
1298       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1299       ref_processor_stw()->verify_no_references_recorded();
1300 
1301       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1302       ClassLoaderDataGraph::purge();
1303       MetaspaceAux::verify_metrics();
1304 
1305       // Note: since we've just done a full GC, concurrent
1306       // marking is no longer active. Therefore we need not
1307       // re-enable reference discovery for the CM ref processor.
1308       // That will be done at the start of the next marking cycle.
1309       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1310       ref_processor_cm()->verify_no_references_recorded();
1311 
1312       reset_gc_time_stamp();
1313       // Since everything potentially moved, we will clear all remembered
1314       // sets, and clear all cards.  Later we will rebuild remembered
1315       // sets. We will also reset the GC time stamps of the regions.
1316       clear_rsets_post_compaction();
1317       check_gc_time_stamps();
1318 
1319       resize_if_necessary_after_full_collection();
1320 
1321       // We should do this after we potentially resize the heap so
1322       // that all the COMMIT / UNCOMMIT events are generated before
1323       // the compaction events.
1324       print_hrm_post_compaction();
1325 
1326       if (_hot_card_cache->use_cache()) {
1327         _hot_card_cache->reset_card_counts();
1328         _hot_card_cache->reset_hot_cache();
1329       }
1330 
1331       // Rebuild remembered sets of all regions.
1332       uint n_workers =
1333         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1334                                                 workers()->active_workers(),
1335                                                 Threads::number_of_non_daemon_threads());
1336       workers()->set_active_workers(n_workers);
1337 
1338       ParRebuildRSTask rebuild_rs_task(this);
1339       workers()->run_task(&rebuild_rs_task);
1340 
1341       // Rebuild the strong code root lists for each region
1342       rebuild_strong_code_roots();
1343 
1344       if (true) { // FIXME
1345         MetaspaceGC::compute_new_size();
1346       }
1347 
1348 #ifdef TRACESPINNING
1349       ParallelTaskTerminator::print_termination_counts();
1350 #endif
1351 
1352       // Discard all rset updates
1353       JavaThread::dirty_card_queue_set().abandon_logs();
1354       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1355 
1356       // At this point there should be no regions in the
1357       // entire heap tagged as young.
1358       assert(check_young_list_empty(), "young list should be empty at this point");
1359 
1360       // Update the number of full collections that have been completed.
1361       increment_old_marking_cycles_completed(false /* concurrent */);
1362 
1363       _hrm.verify_optional();
1364       _verifier->verify_region_sets_optional();
1365 
1366       _verifier->verify_after_gc();
1367 
1368       // Clear the previous marking bitmap, if needed for bitmap verification.
1369       // Note we cannot do this when we clear the next marking bitmap in
1370       // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1371       // objects marked during a full GC against the previous bitmap.
1372       // But we need to clear it before calling check_bitmaps below since
1373       // the full GC has compacted objects and updated TAMS but not updated
1374       // the prev bitmap.
1375       if (G1VerifyBitmaps) {
1376         GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1377         _cm->clear_prev_bitmap(workers());
1378       }
1379       _verifier->check_bitmaps("Full GC End");
1380 
1381       // Start a new incremental collection set for the next pause
1382       assert(collection_set()->head() == NULL, "must be");
1383       collection_set()->start_incremental_building();
1384 
1385       clear_cset_fast_test();
1386 
1387       _allocator->init_mutator_alloc_region();
1388 
1389       g1_policy()->record_full_collection_end();
1390 
1391       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1392       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1393       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1394       // before any GC notifications are raised.
1395       g1mm()->update_sizes();
1396 
1397       gc_epilogue(true);
1398 
1399       heap_transition.print();
1400 
1401       print_heap_after_gc();
1402       print_heap_regions();
1403       trace_heap_after_gc(gc_tracer);
1404 
1405       post_full_gc_dump(gc_timer);
1406     }
1407 
1408     gc_timer->register_gc_end();
1409     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1410   }
1411 
1412   return true;
1413 }
1414 
1415 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1416   // Currently, there is no facility in the do_full_collection(bool) API to notify
1417   // the caller that the collection did not succeed (e.g., because it was locked
1418   // out by the GC locker). So, right now, we'll ignore the return value.
1419   bool dummy = do_full_collection(true,                /* explicit_gc */
1420                                   clear_all_soft_refs);
1421 }
1422 
1423 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1424   // Include bytes that will be pre-allocated to support collections, as "used".
1425   const size_t used_after_gc = used();
1426   const size_t capacity_after_gc = capacity();
1427   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1428 
1429   // This is enforced in arguments.cpp.
1430   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1431          "otherwise the code below doesn't make sense");
1432 
1433   // We don't have floating point command-line arguments
1434   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1435   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1436   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1437   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1438 
1439   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1440   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1441 
1442   // We have to be careful here as these two calculations can overflow
1443   // 32-bit size_t's.
1444   double used_after_gc_d = (double) used_after_gc;
1445   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1446   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1447 
1448   // Let's make sure that they are both under the max heap size, which
1449   // by default will make them fit into a size_t.
1450   double desired_capacity_upper_bound = (double) max_heap_size;
1451   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1452                                     desired_capacity_upper_bound);
1453   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1454                                     desired_capacity_upper_bound);
1455 
1456   // We can now safely turn them into size_t's.
1457   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1458   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1459 
1460   // This assert only makes sense here, before we adjust them
1461   // with respect to the min and max heap size.
1462   assert(minimum_desired_capacity <= maximum_desired_capacity,
1463          "minimum_desired_capacity = " SIZE_FORMAT ", "
1464          "maximum_desired_capacity = " SIZE_FORMAT,
1465          minimum_desired_capacity, maximum_desired_capacity);
1466 
1467   // Should not be greater than the heap max size. No need to adjust
1468   // it with respect to the heap min size as it's a lower bound (i.e.,
1469   // we'll try to make the capacity larger than it, not smaller).
1470   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1471   // Should not be less than the heap min size. No need to adjust it
1472   // with respect to the heap max size as it's an upper bound (i.e.,
1473   // we'll try to make the capacity smaller than it, not greater).
1474   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1475 
1476   if (capacity_after_gc < minimum_desired_capacity) {
1477     // Don't expand unless it's significant
1478     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1479 
1480     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1481                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1482                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1483 
1484     expand(expand_bytes);
1485 
1486     // No expansion, now see if we want to shrink
1487   } else if (capacity_after_gc > maximum_desired_capacity) {
1488     // Capacity too large, compute shrinking size
1489     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1490 
1491     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1492                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1493                               capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1494 
1495     shrink(shrink_bytes);
1496   }
1497 }
1498 
1499 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1500                                                             AllocationContext_t context,
1501                                                             bool do_gc,
1502                                                             bool clear_all_soft_refs,
1503                                                             bool expect_null_mutator_alloc_region,
1504                                                             bool* gc_succeeded) {
1505   *gc_succeeded = true;
1506   // Let's attempt the allocation first.
1507   HeapWord* result =
1508     attempt_allocation_at_safepoint(word_size,
1509                                     context,
1510                                     expect_null_mutator_alloc_region);
1511   if (result != NULL) {
1512     assert(*gc_succeeded, "sanity");
1513     return result;
1514   }
1515 
1516   // In a G1 heap, we're supposed to keep allocation from failing by
1517   // incremental pauses.  Therefore, at least for now, we'll favor
1518   // expansion over collection.  (This might change in the future if we can
1519   // do something smarter than full collection to satisfy a failed alloc.)
1520   result = expand_and_allocate(word_size, context);
1521   if (result != NULL) {
1522     assert(*gc_succeeded, "sanity");
1523     return result;
1524   }
1525 
1526   if (do_gc) {
1527     // Expansion didn't work, we'll try to do a Full GC.
1528     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1529                                        clear_all_soft_refs);
1530   }
1531 
1532   return NULL;
1533 }
1534 
1535 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1536                                                      AllocationContext_t context,
1537                                                      bool* succeeded) {
1538   assert_at_safepoint(true /* should_be_vm_thread */);
1539 
1540   // Attempts to allocate followed by Full GC.
1541   HeapWord* result =
1542     satisfy_failed_allocation_helper(word_size,
1543                                      context,
1544                                      true,  /* do_gc */
1545                                      false, /* clear_all_soft_refs */
1546                                      false, /* expect_null_mutator_alloc_region */
1547                                      succeeded);
1548 
1549   if (result != NULL || !*succeeded) {
1550     return result;
1551   }
1552 
1553   // Attempts to allocate followed by Full GC that will collect all soft references.
1554   result = satisfy_failed_allocation_helper(word_size,
1555                                             context,
1556                                             true, /* do_gc */
1557                                             true, /* clear_all_soft_refs */
1558                                             true, /* expect_null_mutator_alloc_region */
1559                                             succeeded);
1560 
1561   if (result != NULL || !*succeeded) {
1562     return result;
1563   }
1564 
1565   // Attempts to allocate, no GC
1566   result = satisfy_failed_allocation_helper(word_size,
1567                                             context,
1568                                             false, /* do_gc */
1569                                             false, /* clear_all_soft_refs */
1570                                             true,  /* expect_null_mutator_alloc_region */
1571                                             succeeded);
1572 
1573   if (result != NULL) {
1574     assert(*succeeded, "sanity");
1575     return result;
1576   }
1577 
1578   assert(!collector_policy()->should_clear_all_soft_refs(),
1579          "Flag should have been handled and cleared prior to this point");
1580 
1581   // What else?  We might try synchronous finalization later.  If the total
1582   // space available is large enough for the allocation, then a more
1583   // complete compaction phase than we've tried so far might be
1584   // appropriate.
1585   assert(*succeeded, "sanity");
1586   return NULL;
1587 }
1588 
1589 // Attempting to expand the heap sufficiently
1590 // to support an allocation of the given "word_size".  If
1591 // successful, perform the allocation and return the address of the
1592 // allocated block, or else "NULL".
1593 
1594 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1595   assert_at_safepoint(true /* should_be_vm_thread */);
1596 
1597   _verifier->verify_region_sets_optional();
1598 
1599   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1600   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1601                             word_size * HeapWordSize);
1602 
1603 
1604   if (expand(expand_bytes)) {
1605     _hrm.verify_optional();
1606     _verifier->verify_region_sets_optional();
1607     return attempt_allocation_at_safepoint(word_size,
1608                                            context,
1609                                            false /* expect_null_mutator_alloc_region */);
1610   }
1611   return NULL;
1612 }
1613 
1614 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1615   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1616   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1617                                        HeapRegion::GrainBytes);
1618 
1619   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1620                             expand_bytes, aligned_expand_bytes);
1621 
1622   if (is_maximal_no_gc()) {
1623     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1624     return false;
1625   }
1626 
1627   double expand_heap_start_time_sec = os::elapsedTime();
1628   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1629   assert(regions_to_expand > 0, "Must expand by at least one region");
1630 
1631   uint expanded_by = _hrm.expand_by(regions_to_expand);
1632   if (expand_time_ms != NULL) {
1633     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1634   }
1635 
1636   if (expanded_by > 0) {
1637     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1638     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1639     g1_policy()->record_new_heap_size(num_regions());
1640   } else {
1641     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1642 
1643     // The expansion of the virtual storage space was unsuccessful.
1644     // Let's see if it was because we ran out of swap.
1645     if (G1ExitOnExpansionFailure &&
1646         _hrm.available() >= regions_to_expand) {
1647       // We had head room...
1648       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1649     }
1650   }
1651   return regions_to_expand > 0;
1652 }
1653 
1654 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1655   size_t aligned_shrink_bytes =
1656     ReservedSpace::page_align_size_down(shrink_bytes);
1657   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1658                                          HeapRegion::GrainBytes);
1659   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1660 
1661   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1662   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1663 
1664 
1665   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",
1666                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1667   if (num_regions_removed > 0) {
1668     g1_policy()->record_new_heap_size(num_regions());
1669   } else {
1670     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1671   }
1672 }
1673 
1674 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1675   _verifier->verify_region_sets_optional();
1676 
1677   // We should only reach here at the end of a Full GC which means we
1678   // should not not be holding to any GC alloc regions. The method
1679   // below will make sure of that and do any remaining clean up.
1680   _allocator->abandon_gc_alloc_regions();
1681 
1682   // Instead of tearing down / rebuilding the free lists here, we
1683   // could instead use the remove_all_pending() method on free_list to
1684   // remove only the ones that we need to remove.
1685   tear_down_region_sets(true /* free_list_only */);
1686   shrink_helper(shrink_bytes);
1687   rebuild_region_sets(true /* free_list_only */);
1688 
1689   _hrm.verify_optional();
1690   _verifier->verify_region_sets_optional();
1691 }
1692 
1693 // Public methods.
1694 
1695 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1696   CollectedHeap(),
1697   _collector_policy(collector_policy),
1698   _g1_policy(create_g1_policy()),
1699   _collection_set(this, _g1_policy),
1700   _dirty_card_queue_set(false),
1701   _is_alive_closure_cm(this),
1702   _is_alive_closure_stw(this),
1703   _ref_processor_cm(NULL),
1704   _ref_processor_stw(NULL),
1705   _bot(NULL),
1706   _hot_card_cache(NULL),
1707   _g1_rem_set(NULL),
1708   _cg1r(NULL),
1709   _g1mm(NULL),
1710   _refine_cte_cl(NULL),
1711   _preserved_marks_set(true /* in_c_heap */),
1712   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1713   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1714   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1715   _humongous_reclaim_candidates(),
1716   _has_humongous_reclaim_candidates(false),
1717   _archive_allocator(NULL),
1718   _free_regions_coming(false),
1719   _gc_time_stamp(0),
1720   _summary_bytes_used(0),
1721   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1722   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1723   _expand_heap_after_alloc_failure(true),
1724   _old_marking_cycles_started(0),
1725   _old_marking_cycles_completed(0),
1726   _in_cset_fast_test(),
1727   _worker_cset_start_region(NULL),
1728   _worker_cset_start_region_time_stamp(NULL),
1729   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1730   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1731 
1732   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1733                           /* are_GC_task_threads */true,
1734                           /* are_ConcurrentGC_threads */false);
1735   _workers->initialize_workers();
1736   _verifier = new G1HeapVerifier(this);
1737 
1738   _allocator = G1Allocator::create_allocator(this);
1739 
1740   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1741 
1742   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1743 
1744   // Override the default _filler_array_max_size so that no humongous filler
1745   // objects are created.
1746   _filler_array_max_size = _humongous_object_threshold_in_words;
1747 
1748   uint n_queues = ParallelGCThreads;
1749   _task_queues = new RefToScanQueueSet(n_queues);
1750 
1751   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1752   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1753   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1754 
1755   for (uint i = 0; i < n_queues; i++) {
1756     RefToScanQueue* q = new RefToScanQueue();
1757     q->initialize();
1758     _task_queues->register_queue(i, q);
1759     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1760   }
1761   clear_cset_start_regions();
1762 
1763   // Initialize the G1EvacuationFailureALot counters and flags.
1764   NOT_PRODUCT(reset_evacuation_should_fail();)
1765 
1766   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1767 }
1768 
1769 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1770                                                                  size_t size,
1771                                                                  size_t translation_factor) {
1772   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1773   // Allocate a new reserved space, preferring to use large pages.
1774   ReservedSpace rs(size, preferred_page_size);
1775   G1RegionToSpaceMapper* result  =
1776     G1RegionToSpaceMapper::create_mapper(rs,
1777                                          size,
1778                                          rs.alignment(),
1779                                          HeapRegion::GrainBytes,
1780                                          translation_factor,
1781                                          mtGC);
1782 
1783   os::trace_page_sizes_for_requested_size(description,
1784                                           size,
1785                                           preferred_page_size,
1786                                           rs.alignment(),
1787                                           rs.base(),
1788                                           rs.size());
1789 
1790   return result;
1791 }
1792 
1793 jint G1CollectedHeap::initialize() {
1794   CollectedHeap::pre_initialize();
1795   os::enable_vtime();
1796 
1797   // Necessary to satisfy locking discipline assertions.
1798 
1799   MutexLocker x(Heap_lock);
1800 
1801   // While there are no constraints in the GC code that HeapWordSize
1802   // be any particular value, there are multiple other areas in the
1803   // system which believe this to be true (e.g. oop->object_size in some
1804   // cases incorrectly returns the size in wordSize units rather than
1805   // HeapWordSize).
1806   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1807 
1808   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1809   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1810   size_t heap_alignment = collector_policy()->heap_alignment();
1811 
1812   // Ensure that the sizes are properly aligned.
1813   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1814   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1815   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1816 
1817   _refine_cte_cl = new RefineCardTableEntryClosure();
1818 
1819   jint ecode = JNI_OK;
1820   _cg1r = ConcurrentG1Refine::create(_refine_cte_cl, &ecode);
1821   if (_cg1r == NULL) {
1822     return ecode;
1823   }
1824 
1825   // Reserve the maximum.
1826 
1827   // When compressed oops are enabled, the preferred heap base
1828   // is calculated by subtracting the requested size from the
1829   // 32Gb boundary and using the result as the base address for
1830   // heap reservation. If the requested size is not aligned to
1831   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1832   // into the ReservedHeapSpace constructor) then the actual
1833   // base of the reserved heap may end up differing from the
1834   // address that was requested (i.e. the preferred heap base).
1835   // If this happens then we could end up using a non-optimal
1836   // compressed oops mode.
1837 
1838   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1839                                                  heap_alignment);
1840 
1841   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1842 
1843   // Create the barrier set for the entire reserved region.
1844   G1SATBCardTableLoggingModRefBS* bs
1845     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1846   bs->initialize();
1847   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1848   set_barrier_set(bs);
1849 
1850   // Create the hot card cache.
1851   _hot_card_cache = new G1HotCardCache(this);
1852 
1853   // Also create a G1 rem set.
1854   _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1855 
1856   // Carve out the G1 part of the heap.
1857   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1858   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1859   G1RegionToSpaceMapper* heap_storage =
1860     G1RegionToSpaceMapper::create_mapper(g1_rs,
1861                                          g1_rs.size(),
1862                                          page_size,
1863                                          HeapRegion::GrainBytes,
1864                                          1,
1865                                          mtJavaHeap);
1866   os::trace_page_sizes("Heap",
1867                        collector_policy()->min_heap_byte_size(),
1868                        max_byte_size,
1869                        page_size,
1870                        heap_rs.base(),
1871                        heap_rs.size());
1872   heap_storage->set_mapping_changed_listener(&_listener);
1873 
1874   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1875   G1RegionToSpaceMapper* bot_storage =
1876     create_aux_memory_mapper("Block Offset Table",
1877                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1878                              G1BlockOffsetTable::heap_map_factor());
1879 
1880   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1881   G1RegionToSpaceMapper* cardtable_storage =
1882     create_aux_memory_mapper("Card Table",
1883                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1884                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1885 
1886   G1RegionToSpaceMapper* card_counts_storage =
1887     create_aux_memory_mapper("Card Counts Table",
1888                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1889                              G1CardCounts::heap_map_factor());
1890 
1891   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1892   G1RegionToSpaceMapper* prev_bitmap_storage =
1893     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1894   G1RegionToSpaceMapper* next_bitmap_storage =
1895     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1896 
1897   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1898   g1_barrier_set()->initialize(cardtable_storage);
1899   // Do later initialization work for concurrent refinement.
1900   _hot_card_cache->initialize(card_counts_storage);
1901 
1902   // 6843694 - ensure that the maximum region index can fit
1903   // in the remembered set structures.
1904   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1905   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1906 
1907   g1_rem_set()->initialize(max_capacity(), max_regions());
1908 
1909   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1910   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1911   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1912             "too many cards per region");
1913 
1914   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1915 
1916   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1917 
1918   {
1919     HeapWord* start = _hrm.reserved().start();
1920     HeapWord* end = _hrm.reserved().end();
1921     size_t granularity = HeapRegion::GrainBytes;
1922 
1923     _in_cset_fast_test.initialize(start, end, granularity);
1924     _humongous_reclaim_candidates.initialize(start, end, granularity);
1925   }
1926 
1927   // Create the G1ConcurrentMark data structure and thread.
1928   // (Must do this late, so that "max_regions" is defined.)
1929   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1930   if (_cm == NULL || !_cm->completed_initialization()) {
1931     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1932     return JNI_ENOMEM;
1933   }
1934   _cmThread = _cm->cmThread();
1935 
1936   // Now expand into the initial heap size.
1937   if (!expand(init_byte_size)) {
1938     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1939     return JNI_ENOMEM;
1940   }
1941 
1942   // Perform any initialization actions delegated to the policy.
1943   g1_policy()->init(this, &_collection_set);
1944 
1945   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1946                                                SATB_Q_FL_lock,
1947                                                G1SATBProcessCompletedThreshold,
1948                                                Shared_SATB_Q_lock);
1949 
1950   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1951                                                 DirtyCardQ_CBL_mon,
1952                                                 DirtyCardQ_FL_lock,
1953                                                 (int)concurrent_g1_refine()->yellow_zone(),
1954                                                 (int)concurrent_g1_refine()->red_zone(),
1955                                                 Shared_DirtyCardQ_lock,
1956                                                 NULL,  // fl_owner
1957                                                 true); // init_free_ids
1958 
1959   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1960                                     DirtyCardQ_CBL_mon,
1961                                     DirtyCardQ_FL_lock,
1962                                     -1, // never trigger processing
1963                                     -1, // no limit on length
1964                                     Shared_DirtyCardQ_lock,
1965                                     &JavaThread::dirty_card_queue_set());
1966 
1967   // Here we allocate the dummy HeapRegion that is required by the
1968   // G1AllocRegion class.
1969   HeapRegion* dummy_region = _hrm.get_dummy_region();
1970 
1971   // We'll re-use the same region whether the alloc region will
1972   // require BOT updates or not and, if it doesn't, then a non-young
1973   // region will complain that it cannot support allocations without
1974   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1975   dummy_region->set_eden();
1976   // Make sure it's full.
1977   dummy_region->set_top(dummy_region->end());
1978   G1AllocRegion::setup(this, dummy_region);
1979 
1980   _allocator->init_mutator_alloc_region();
1981 
1982   // Do create of the monitoring and management support so that
1983   // values in the heap have been properly initialized.
1984   _g1mm = new G1MonitoringSupport(this);
1985 
1986   G1StringDedup::initialize();
1987 
1988   _preserved_marks_set.init(ParallelGCThreads);
1989 
1990   return JNI_OK;
1991 }
1992 
1993 void G1CollectedHeap::stop() {
1994   // Stop all concurrent threads. We do this to make sure these threads
1995   // do not continue to execute and access resources (e.g. logging)
1996   // that are destroyed during shutdown.
1997   _cg1r->stop();
1998   _cmThread->stop();
1999   if (G1StringDedup::is_enabled()) {
2000     G1StringDedup::stop();
2001   }
2002 }
2003 
2004 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2005   return HeapRegion::max_region_size();
2006 }
2007 
2008 void G1CollectedHeap::post_initialize() {
2009   ref_processing_init();
2010 }
2011 
2012 void G1CollectedHeap::ref_processing_init() {
2013   // Reference processing in G1 currently works as follows:
2014   //
2015   // * There are two reference processor instances. One is
2016   //   used to record and process discovered references
2017   //   during concurrent marking; the other is used to
2018   //   record and process references during STW pauses
2019   //   (both full and incremental).
2020   // * Both ref processors need to 'span' the entire heap as
2021   //   the regions in the collection set may be dotted around.
2022   //
2023   // * For the concurrent marking ref processor:
2024   //   * Reference discovery is enabled at initial marking.
2025   //   * Reference discovery is disabled and the discovered
2026   //     references processed etc during remarking.
2027   //   * Reference discovery is MT (see below).
2028   //   * Reference discovery requires a barrier (see below).
2029   //   * Reference processing may or may not be MT
2030   //     (depending on the value of ParallelRefProcEnabled
2031   //     and ParallelGCThreads).
2032   //   * A full GC disables reference discovery by the CM
2033   //     ref processor and abandons any entries on it's
2034   //     discovered lists.
2035   //
2036   // * For the STW processor:
2037   //   * Non MT discovery is enabled at the start of a full GC.
2038   //   * Processing and enqueueing during a full GC is non-MT.
2039   //   * During a full GC, references are processed after marking.
2040   //
2041   //   * Discovery (may or may not be MT) is enabled at the start
2042   //     of an incremental evacuation pause.
2043   //   * References are processed near the end of a STW evacuation pause.
2044   //   * For both types of GC:
2045   //     * Discovery is atomic - i.e. not concurrent.
2046   //     * Reference discovery will not need a barrier.
2047 
2048   MemRegion mr = reserved_region();
2049 
2050   // Concurrent Mark ref processor
2051   _ref_processor_cm =
2052     new ReferenceProcessor(mr,    // span
2053                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2054                                 // mt processing
2055                            ParallelGCThreads,
2056                                 // degree of mt processing
2057                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2058                                 // mt discovery
2059                            MAX2(ParallelGCThreads, ConcGCThreads),
2060                                 // degree of mt discovery
2061                            false,
2062                                 // Reference discovery is not atomic
2063                            &_is_alive_closure_cm);
2064                                 // is alive closure
2065                                 // (for efficiency/performance)
2066 
2067   // STW ref processor
2068   _ref_processor_stw =
2069     new ReferenceProcessor(mr,    // span
2070                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2071                                 // mt processing
2072                            ParallelGCThreads,
2073                                 // degree of mt processing
2074                            (ParallelGCThreads > 1),
2075                                 // mt discovery
2076                            ParallelGCThreads,
2077                                 // degree of mt discovery
2078                            true,
2079                                 // Reference discovery is atomic
2080                            &_is_alive_closure_stw);
2081                                 // is alive closure
2082                                 // (for efficiency/performance)
2083 }
2084 
2085 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2086   return _collector_policy;
2087 }
2088 
2089 size_t G1CollectedHeap::capacity() const {
2090   return _hrm.length() * HeapRegion::GrainBytes;
2091 }
2092 
2093 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2094   hr->reset_gc_time_stamp();
2095 }
2096 
2097 #ifndef PRODUCT
2098 
2099 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2100 private:
2101   unsigned _gc_time_stamp;
2102   bool _failures;
2103 
2104 public:
2105   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2106     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2107 
2108   virtual bool doHeapRegion(HeapRegion* hr) {
2109     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2110     if (_gc_time_stamp != region_gc_time_stamp) {
2111       log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2112                             region_gc_time_stamp, _gc_time_stamp);
2113       _failures = true;
2114     }
2115     return false;
2116   }
2117 
2118   bool failures() { return _failures; }
2119 };
2120 
2121 void G1CollectedHeap::check_gc_time_stamps() {
2122   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2123   heap_region_iterate(&cl);
2124   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2125 }
2126 #endif // PRODUCT
2127 
2128 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2129   _hot_card_cache->drain(cl, worker_i);
2130 }
2131 
2132 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2133   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2134   size_t n_completed_buffers = 0;
2135   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2136     n_completed_buffers++;
2137   }
2138   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2139   dcqs.clear_n_completed_buffers();
2140   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2141 }
2142 
2143 // Computes the sum of the storage used by the various regions.
2144 size_t G1CollectedHeap::used() const {
2145   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2146   if (_archive_allocator != NULL) {
2147     result += _archive_allocator->used();
2148   }
2149   return result;
2150 }
2151 
2152 size_t G1CollectedHeap::used_unlocked() const {
2153   return _summary_bytes_used;
2154 }
2155 
2156 class SumUsedClosure: public HeapRegionClosure {
2157   size_t _used;
2158 public:
2159   SumUsedClosure() : _used(0) {}
2160   bool doHeapRegion(HeapRegion* r) {
2161     _used += r->used();
2162     return false;
2163   }
2164   size_t result() { return _used; }
2165 };
2166 
2167 size_t G1CollectedHeap::recalculate_used() const {
2168   double recalculate_used_start = os::elapsedTime();
2169 
2170   SumUsedClosure blk;
2171   heap_region_iterate(&blk);
2172 
2173   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2174   return blk.result();
2175 }
2176 
2177 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2178   switch (cause) {
2179     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2180     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2181     case GCCause::_update_allocation_context_stats_inc: return true;
2182     case GCCause::_wb_conc_mark:                        return true;
2183     default :                                           return false;
2184   }
2185 }
2186 
2187 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2188   switch (cause) {
2189     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2190     case GCCause::_g1_humongous_allocation: return true;
2191     default:                                return is_user_requested_concurrent_full_gc(cause);
2192   }
2193 }
2194 
2195 #ifndef PRODUCT
2196 void G1CollectedHeap::allocate_dummy_regions() {
2197   // Let's fill up most of the region
2198   size_t word_size = HeapRegion::GrainWords - 1024;
2199   // And as a result the region we'll allocate will be humongous.
2200   guarantee(is_humongous(word_size), "sanity");
2201 
2202   // _filler_array_max_size is set to humongous object threshold
2203   // but temporarily change it to use CollectedHeap::fill_with_object().
2204   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2205 
2206   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2207     // Let's use the existing mechanism for the allocation
2208     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2209                                                  AllocationContext::system());
2210     if (dummy_obj != NULL) {
2211       MemRegion mr(dummy_obj, word_size);
2212       CollectedHeap::fill_with_object(mr);
2213     } else {
2214       // If we can't allocate once, we probably cannot allocate
2215       // again. Let's get out of the loop.
2216       break;
2217     }
2218   }
2219 }
2220 #endif // !PRODUCT
2221 
2222 void G1CollectedHeap::increment_old_marking_cycles_started() {
2223   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2224          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2225          "Wrong marking cycle count (started: %d, completed: %d)",
2226          _old_marking_cycles_started, _old_marking_cycles_completed);
2227 
2228   _old_marking_cycles_started++;
2229 }
2230 
2231 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2232   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2233 
2234   // We assume that if concurrent == true, then the caller is a
2235   // concurrent thread that was joined the Suspendible Thread
2236   // Set. If there's ever a cheap way to check this, we should add an
2237   // assert here.
2238 
2239   // Given that this method is called at the end of a Full GC or of a
2240   // concurrent cycle, and those can be nested (i.e., a Full GC can
2241   // interrupt a concurrent cycle), the number of full collections
2242   // completed should be either one (in the case where there was no
2243   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2244   // behind the number of full collections started.
2245 
2246   // This is the case for the inner caller, i.e. a Full GC.
2247   assert(concurrent ||
2248          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2249          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2250          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2251          "is inconsistent with _old_marking_cycles_completed = %u",
2252          _old_marking_cycles_started, _old_marking_cycles_completed);
2253 
2254   // This is the case for the outer caller, i.e. the concurrent cycle.
2255   assert(!concurrent ||
2256          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2257          "for outer caller (concurrent cycle): "
2258          "_old_marking_cycles_started = %u "
2259          "is inconsistent with _old_marking_cycles_completed = %u",
2260          _old_marking_cycles_started, _old_marking_cycles_completed);
2261 
2262   _old_marking_cycles_completed += 1;
2263 
2264   // We need to clear the "in_progress" flag in the CM thread before
2265   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2266   // is set) so that if a waiter requests another System.gc() it doesn't
2267   // incorrectly see that a marking cycle is still in progress.
2268   if (concurrent) {
2269     _cmThread->set_idle();
2270   }
2271 
2272   // This notify_all() will ensure that a thread that called
2273   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2274   // and it's waiting for a full GC to finish will be woken up. It is
2275   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2276   FullGCCount_lock->notify_all();
2277 }
2278 
2279 void G1CollectedHeap::collect(GCCause::Cause cause) {
2280   assert_heap_not_locked();
2281 
2282   uint gc_count_before;
2283   uint old_marking_count_before;
2284   uint full_gc_count_before;
2285   bool retry_gc;
2286 
2287   do {
2288     retry_gc = false;
2289 
2290     {
2291       MutexLocker ml(Heap_lock);
2292 
2293       // Read the GC count while holding the Heap_lock
2294       gc_count_before = total_collections();
2295       full_gc_count_before = total_full_collections();
2296       old_marking_count_before = _old_marking_cycles_started;
2297     }
2298 
2299     if (should_do_concurrent_full_gc(cause)) {
2300       // Schedule an initial-mark evacuation pause that will start a
2301       // concurrent cycle. We're setting word_size to 0 which means that
2302       // we are not requesting a post-GC allocation.
2303       VM_G1IncCollectionPause op(gc_count_before,
2304                                  0,     /* word_size */
2305                                  true,  /* should_initiate_conc_mark */
2306                                  g1_policy()->max_pause_time_ms(),
2307                                  cause);
2308       op.set_allocation_context(AllocationContext::current());
2309 
2310       VMThread::execute(&op);
2311       if (!op.pause_succeeded()) {
2312         if (old_marking_count_before == _old_marking_cycles_started) {
2313           retry_gc = op.should_retry_gc();
2314         } else {
2315           // A Full GC happened while we were trying to schedule the
2316           // initial-mark GC. No point in starting a new cycle given
2317           // that the whole heap was collected anyway.
2318         }
2319 
2320         if (retry_gc) {
2321           if (GCLocker::is_active_and_needs_gc()) {
2322             GCLocker::stall_until_clear();
2323           }
2324         }
2325       }
2326     } else {
2327       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2328           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2329 
2330         // Schedule a standard evacuation pause. We're setting word_size
2331         // to 0 which means that we are not requesting a post-GC allocation.
2332         VM_G1IncCollectionPause op(gc_count_before,
2333                                    0,     /* word_size */
2334                                    false, /* should_initiate_conc_mark */
2335                                    g1_policy()->max_pause_time_ms(),
2336                                    cause);
2337         VMThread::execute(&op);
2338       } else {
2339         // Schedule a Full GC.
2340         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2341         VMThread::execute(&op);
2342       }
2343     }
2344   } while (retry_gc);
2345 }
2346 
2347 bool G1CollectedHeap::is_in(const void* p) const {
2348   if (_hrm.reserved().contains(p)) {
2349     // Given that we know that p is in the reserved space,
2350     // heap_region_containing() should successfully
2351     // return the containing region.
2352     HeapRegion* hr = heap_region_containing(p);
2353     return hr->is_in(p);
2354   } else {
2355     return false;
2356   }
2357 }
2358 
2359 #ifdef ASSERT
2360 bool G1CollectedHeap::is_in_exact(const void* p) const {
2361   bool contains = reserved_region().contains(p);
2362   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2363   if (contains && available) {
2364     return true;
2365   } else {
2366     return false;
2367   }
2368 }
2369 #endif
2370 
2371 bool G1CollectedHeap::obj_in_cs(oop obj) {
2372   HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2373   return r != NULL && r->in_collection_set();
2374 }
2375 
2376 // Iteration functions.
2377 
2378 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2379 
2380 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2381   ExtendedOopClosure* _cl;
2382 public:
2383   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2384   bool doHeapRegion(HeapRegion* r) {
2385     if (!r->is_continues_humongous()) {
2386       r->oop_iterate(_cl);
2387     }
2388     return false;
2389   }
2390 };
2391 
2392 // Iterates an ObjectClosure over all objects within a HeapRegion.
2393 
2394 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2395   ObjectClosure* _cl;
2396 public:
2397   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2398   bool doHeapRegion(HeapRegion* r) {
2399     if (!r->is_continues_humongous()) {
2400       r->object_iterate(_cl);
2401     }
2402     return false;
2403   }
2404 };
2405 
2406 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2407   IterateObjectClosureRegionClosure blk(cl);
2408   heap_region_iterate(&blk);
2409 }
2410 
2411 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2412   _hrm.iterate(cl);
2413 }
2414 
2415 void
2416 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2417                                          uint worker_id,
2418                                          HeapRegionClaimer *hrclaimer,
2419                                          bool concurrent) const {
2420   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2421 }
2422 
2423 // Clear the cached CSet starting regions and (more importantly)
2424 // the time stamps. Called when we reset the GC time stamp.
2425 void G1CollectedHeap::clear_cset_start_regions() {
2426   assert(_worker_cset_start_region != NULL, "sanity");
2427   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2428 
2429   for (uint i = 0; i < ParallelGCThreads; i++) {
2430     _worker_cset_start_region[i] = NULL;
2431     _worker_cset_start_region_time_stamp[i] = 0;
2432   }
2433 }
2434 
2435 // Given the id of a worker, obtain or calculate a suitable
2436 // starting region for iterating over the current collection set.
2437 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2438   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2439 
2440   HeapRegion* result = NULL;
2441   unsigned gc_time_stamp = get_gc_time_stamp();
2442 
2443   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2444     // Cached starting region for current worker was set
2445     // during the current pause - so it's valid.
2446     // Note: the cached starting heap region may be NULL
2447     // (when the collection set is empty).
2448     result = _worker_cset_start_region[worker_i];
2449     assert(result == NULL || result->in_collection_set(), "sanity");
2450     return result;
2451   }
2452 
2453   // The cached entry was not valid so let's calculate
2454   // a suitable starting heap region for this worker.
2455 
2456   // We want the parallel threads to start their collection
2457   // set iteration at different collection set regions to
2458   // avoid contention.
2459   // If we have:
2460   //          n collection set regions
2461   //          p threads
2462   // Then thread t will start at region floor ((t * n) / p)
2463 
2464   result = collection_set()->head();
2465   uint cs_size = collection_set()->region_length();
2466   uint active_workers = workers()->active_workers();
2467 
2468   uint end_ind   = (cs_size * worker_i) / active_workers;
2469   uint start_ind = 0;
2470 
2471   if (worker_i > 0 &&
2472       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2473     // Previous workers starting region is valid
2474     // so let's iterate from there
2475     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2476     OrderAccess::loadload();
2477     result = _worker_cset_start_region[worker_i - 1];
2478   }
2479 
2480   for (uint i = start_ind; i < end_ind; i++) {
2481     result = result->next_in_collection_set();
2482   }
2483 
2484   // Note: the calculated starting heap region may be NULL
2485   // (when the collection set is empty).
2486   assert(result == NULL || result->in_collection_set(), "sanity");
2487   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2488          "should be updated only once per pause");
2489   _worker_cset_start_region[worker_i] = result;
2490   OrderAccess::storestore();
2491   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2492   return result;
2493 }
2494 
2495 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2496   HeapRegion* r = collection_set()->head();
2497   while (r != NULL) {
2498     HeapRegion* next = r->next_in_collection_set();
2499     if (cl->doHeapRegion(r)) {
2500       cl->incomplete();
2501       return;
2502     }
2503     r = next;
2504   }
2505 }
2506 
2507 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2508                                                   HeapRegionClosure *cl) {
2509   if (r == NULL) {
2510     // The CSet is empty so there's nothing to do.
2511     return;
2512   }
2513 
2514   assert(r->in_collection_set(),
2515          "Start region must be a member of the collection set.");
2516   HeapRegion* cur = r;
2517   while (cur != NULL) {
2518     HeapRegion* next = cur->next_in_collection_set();
2519     if (cl->doHeapRegion(cur) && false) {
2520       cl->incomplete();
2521       return;
2522     }
2523     cur = next;
2524   }
2525   cur = collection_set()->head();
2526   while (cur != r) {
2527     HeapRegion* next = cur->next_in_collection_set();
2528     if (cl->doHeapRegion(cur) && false) {
2529       cl->incomplete();
2530       return;
2531     }
2532     cur = next;
2533   }
2534 }
2535 
2536 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2537   HeapRegion* result = _hrm.next_region_in_heap(from);
2538   while (result != NULL && result->is_pinned()) {
2539     result = _hrm.next_region_in_heap(result);
2540   }
2541   return result;
2542 }
2543 
2544 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2545   HeapRegion* hr = heap_region_containing(addr);
2546   return hr->block_start(addr);
2547 }
2548 
2549 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2550   HeapRegion* hr = heap_region_containing(addr);
2551   return hr->block_size(addr);
2552 }
2553 
2554 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2555   HeapRegion* hr = heap_region_containing(addr);
2556   return hr->block_is_obj(addr);
2557 }
2558 
2559 bool G1CollectedHeap::supports_tlab_allocation() const {
2560   return true;
2561 }
2562 
2563 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2564   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2565 }
2566 
2567 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2568   return _eden.length() * HeapRegion::GrainBytes;
2569 }
2570 
2571 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2572 // must be equal to the humongous object limit.
2573 size_t G1CollectedHeap::max_tlab_size() const {
2574   return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2575 }
2576 
2577 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2578   AllocationContext_t context = AllocationContext::current();
2579   return _allocator->unsafe_max_tlab_alloc(context);
2580 }
2581 
2582 size_t G1CollectedHeap::max_capacity() const {
2583   return _hrm.reserved().byte_size();
2584 }
2585 
2586 jlong G1CollectedHeap::millis_since_last_gc() {
2587   // assert(false, "NYI");
2588   return 0;
2589 }
2590 
2591 void G1CollectedHeap::prepare_for_verify() {
2592   _verifier->prepare_for_verify();
2593 }
2594 
2595 void G1CollectedHeap::verify(VerifyOption vo) {
2596   _verifier->verify(vo);
2597 }
2598 
2599 class PrintRegionClosure: public HeapRegionClosure {
2600   outputStream* _st;
2601 public:
2602   PrintRegionClosure(outputStream* st) : _st(st) {}
2603   bool doHeapRegion(HeapRegion* r) {
2604     r->print_on(_st);
2605     return false;
2606   }
2607 };
2608 
2609 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2610                                        const HeapRegion* hr,
2611                                        const VerifyOption vo) const {
2612   switch (vo) {
2613   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2614   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2615   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
2616   default:                            ShouldNotReachHere();
2617   }
2618   return false; // keep some compilers happy
2619 }
2620 
2621 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2622                                        const VerifyOption vo) const {
2623   switch (vo) {
2624   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2625   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2626   case VerifyOption_G1UseMarkWord: {
2627     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2628     return !obj->is_gc_marked() && !hr->is_archive();
2629   }
2630   default:                            ShouldNotReachHere();
2631   }
2632   return false; // keep some compilers happy
2633 }
2634 
2635 void G1CollectedHeap::print_heap_regions() const {
2636   Log(gc, heap, region) log;
2637   if (log.is_trace()) {
2638     ResourceMark rm;
2639     print_regions_on(log.trace_stream());
2640   }
2641 }
2642 
2643 void G1CollectedHeap::print_on(outputStream* st) const {
2644   st->print(" %-20s", "garbage-first heap");
2645   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2646             capacity()/K, used_unlocked()/K);
2647   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2648             p2i(_hrm.reserved().start()),
2649             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2650             p2i(_hrm.reserved().end()));
2651   st->cr();
2652   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2653   uint young_regions = young_regions_count();
2654   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2655             (size_t) young_regions * HeapRegion::GrainBytes / K);
2656   uint survivor_regions = survivor_regions_count();
2657   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2658             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2659   st->cr();
2660   MetaspaceAux::print_on(st);
2661 }
2662 
2663 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2664   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2665                "HS=humongous(starts), HC=humongous(continues), "
2666                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2667                "AC=allocation context, "
2668                "TAMS=top-at-mark-start (previous, next)");
2669   PrintRegionClosure blk(st);
2670   heap_region_iterate(&blk);
2671 }
2672 
2673 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2674   print_on(st);
2675 
2676   // Print the per-region information.
2677   print_regions_on(st);
2678 }
2679 
2680 void G1CollectedHeap::print_on_error(outputStream* st) const {
2681   this->CollectedHeap::print_on_error(st);
2682 
2683   if (_cm != NULL) {
2684     st->cr();
2685     _cm->print_on_error(st);
2686   }
2687 }
2688 
2689 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2690   workers()->print_worker_threads_on(st);
2691   _cmThread->print_on(st);
2692   st->cr();
2693   _cm->print_worker_threads_on(st);
2694   _cg1r->print_worker_threads_on(st); // also prints the sample thread
2695   if (G1StringDedup::is_enabled()) {
2696     G1StringDedup::print_worker_threads_on(st);
2697   }
2698 }
2699 
2700 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2701   workers()->threads_do(tc);
2702   tc->do_thread(_cmThread);
2703   _cm->threads_do(tc);
2704   _cg1r->threads_do(tc); // also iterates over the sample thread
2705   if (G1StringDedup::is_enabled()) {
2706     G1StringDedup::threads_do(tc);
2707   }
2708 }
2709 
2710 void G1CollectedHeap::print_tracing_info() const {
2711   g1_rem_set()->print_summary_info();
2712   concurrent_mark()->print_summary_info();
2713 }
2714 
2715 #ifndef PRODUCT
2716 // Helpful for debugging RSet issues.
2717 
2718 class PrintRSetsClosure : public HeapRegionClosure {
2719 private:
2720   const char* _msg;
2721   size_t _occupied_sum;
2722 
2723 public:
2724   bool doHeapRegion(HeapRegion* r) {
2725     HeapRegionRemSet* hrrs = r->rem_set();
2726     size_t occupied = hrrs->occupied();
2727     _occupied_sum += occupied;
2728 
2729     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2730     if (occupied == 0) {
2731       tty->print_cr("  RSet is empty");
2732     } else {
2733       hrrs->print();
2734     }
2735     tty->print_cr("----------");
2736     return false;
2737   }
2738 
2739   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2740     tty->cr();
2741     tty->print_cr("========================================");
2742     tty->print_cr("%s", msg);
2743     tty->cr();
2744   }
2745 
2746   ~PrintRSetsClosure() {
2747     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2748     tty->print_cr("========================================");
2749     tty->cr();
2750   }
2751 };
2752 
2753 void G1CollectedHeap::print_cset_rsets() {
2754   PrintRSetsClosure cl("Printing CSet RSets");
2755   collection_set_iterate(&cl);
2756 }
2757 
2758 void G1CollectedHeap::print_all_rsets() {
2759   PrintRSetsClosure cl("Printing All RSets");;
2760   heap_region_iterate(&cl);
2761 }
2762 #endif // PRODUCT
2763 
2764 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2765 
2766   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2767   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2768   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2769 
2770   size_t eden_capacity_bytes =
2771     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2772 
2773   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2774   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2775                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2776 }
2777 
2778 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2779   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2780                        stats->unused(), stats->used(), stats->region_end_waste(),
2781                        stats->regions_filled(), stats->direct_allocated(),
2782                        stats->failure_used(), stats->failure_waste());
2783 }
2784 
2785 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2786   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2787   gc_tracer->report_gc_heap_summary(when, heap_summary);
2788 
2789   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2790   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2791 }
2792 
2793 G1CollectedHeap* G1CollectedHeap::heap() {
2794   CollectedHeap* heap = Universe::heap();
2795   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2796   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2797   return (G1CollectedHeap*)heap;
2798 }
2799 
2800 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2801   // always_do_update_barrier = false;
2802   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2803   // Fill TLAB's and such
2804   accumulate_statistics_all_tlabs();
2805   ensure_parsability(true);
2806 
2807   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2808 }
2809 
2810 void G1CollectedHeap::gc_epilogue(bool full) {
2811   // we are at the end of the GC. Total collections has already been increased.
2812   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2813 
2814   // FIXME: what is this about?
2815   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2816   // is set.
2817 #if defined(COMPILER2) || INCLUDE_JVMCI
2818   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2819 #endif
2820   // always_do_update_barrier = true;
2821 
2822   resize_all_tlabs();
2823   allocation_context_stats().update(full);
2824 
2825   // We have just completed a GC. Update the soft reference
2826   // policy with the new heap occupancy
2827   Universe::update_heap_info_at_gc();
2828 }
2829 
2830 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2831                                                uint gc_count_before,
2832                                                bool* succeeded,
2833                                                GCCause::Cause gc_cause) {
2834   assert_heap_not_locked_and_not_at_safepoint();
2835   VM_G1IncCollectionPause op(gc_count_before,
2836                              word_size,
2837                              false, /* should_initiate_conc_mark */
2838                              g1_policy()->max_pause_time_ms(),
2839                              gc_cause);
2840 
2841   op.set_allocation_context(AllocationContext::current());
2842   VMThread::execute(&op);
2843 
2844   HeapWord* result = op.result();
2845   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2846   assert(result == NULL || ret_succeeded,
2847          "the result should be NULL if the VM did not succeed");
2848   *succeeded = ret_succeeded;
2849 
2850   assert_heap_not_locked();
2851   return result;
2852 }
2853 
2854 void
2855 G1CollectedHeap::doConcurrentMark() {
2856   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2857   if (!_cmThread->in_progress()) {
2858     _cmThread->set_started();
2859     CGC_lock->notify();
2860   }
2861 }
2862 
2863 size_t G1CollectedHeap::pending_card_num() {
2864   size_t extra_cards = 0;
2865   JavaThread *curr = Threads::first();
2866   while (curr != NULL) {
2867     DirtyCardQueue& dcq = curr->dirty_card_queue();
2868     extra_cards += dcq.size();
2869     curr = curr->next();
2870   }
2871   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2872   size_t buffer_size = dcqs.buffer_size();
2873   size_t buffer_num = dcqs.completed_buffers_num();
2874 
2875   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2876   // in bytes - not the number of 'entries'. We need to convert
2877   // into a number of cards.
2878   return (buffer_size * buffer_num + extra_cards) / oopSize;
2879 }
2880 
2881 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2882  private:
2883   size_t _total_humongous;
2884   size_t _candidate_humongous;
2885 
2886   DirtyCardQueue _dcq;
2887 
2888   // We don't nominate objects with many remembered set entries, on
2889   // the assumption that such objects are likely still live.
2890   bool is_remset_small(HeapRegion* region) const {
2891     HeapRegionRemSet* const rset = region->rem_set();
2892     return G1EagerReclaimHumongousObjectsWithStaleRefs
2893       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2894       : rset->is_empty();
2895   }
2896 
2897   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2898     assert(region->is_starts_humongous(), "Must start a humongous object");
2899 
2900     oop obj = oop(region->bottom());
2901 
2902     // Dead objects cannot be eager reclaim candidates. Due to class
2903     // unloading it is unsafe to query their classes so we return early.
2904     if (heap->is_obj_dead(obj, region)) {
2905       return false;
2906     }
2907 
2908     // Candidate selection must satisfy the following constraints
2909     // while concurrent marking is in progress:
2910     //
2911     // * In order to maintain SATB invariants, an object must not be
2912     // reclaimed if it was allocated before the start of marking and
2913     // has not had its references scanned.  Such an object must have
2914     // its references (including type metadata) scanned to ensure no
2915     // live objects are missed by the marking process.  Objects
2916     // allocated after the start of concurrent marking don't need to
2917     // be scanned.
2918     //
2919     // * An object must not be reclaimed if it is on the concurrent
2920     // mark stack.  Objects allocated after the start of concurrent
2921     // marking are never pushed on the mark stack.
2922     //
2923     // Nominating only objects allocated after the start of concurrent
2924     // marking is sufficient to meet both constraints.  This may miss
2925     // some objects that satisfy the constraints, but the marking data
2926     // structures don't support efficiently performing the needed
2927     // additional tests or scrubbing of the mark stack.
2928     //
2929     // However, we presently only nominate is_typeArray() objects.
2930     // A humongous object containing references induces remembered
2931     // set entries on other regions.  In order to reclaim such an
2932     // object, those remembered sets would need to be cleaned up.
2933     //
2934     // We also treat is_typeArray() objects specially, allowing them
2935     // to be reclaimed even if allocated before the start of
2936     // concurrent mark.  For this we rely on mark stack insertion to
2937     // exclude is_typeArray() objects, preventing reclaiming an object
2938     // that is in the mark stack.  We also rely on the metadata for
2939     // such objects to be built-in and so ensured to be kept live.
2940     // Frequent allocation and drop of large binary blobs is an
2941     // important use case for eager reclaim, and this special handling
2942     // may reduce needed headroom.
2943 
2944     return obj->is_typeArray() && is_remset_small(region);
2945   }
2946 
2947  public:
2948   RegisterHumongousWithInCSetFastTestClosure()
2949   : _total_humongous(0),
2950     _candidate_humongous(0),
2951     _dcq(&JavaThread::dirty_card_queue_set()) {
2952   }
2953 
2954   virtual bool doHeapRegion(HeapRegion* r) {
2955     if (!r->is_starts_humongous()) {
2956       return false;
2957     }
2958     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2959 
2960     bool is_candidate = humongous_region_is_candidate(g1h, r);
2961     uint rindex = r->hrm_index();
2962     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2963     if (is_candidate) {
2964       _candidate_humongous++;
2965       g1h->register_humongous_region_with_cset(rindex);
2966       // Is_candidate already filters out humongous object with large remembered sets.
2967       // If we have a humongous object with a few remembered sets, we simply flush these
2968       // remembered set entries into the DCQS. That will result in automatic
2969       // re-evaluation of their remembered set entries during the following evacuation
2970       // phase.
2971       if (!r->rem_set()->is_empty()) {
2972         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2973                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2974         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2975         HeapRegionRemSetIterator hrrs(r->rem_set());
2976         size_t card_index;
2977         while (hrrs.has_next(card_index)) {
2978           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2979           // The remembered set might contain references to already freed
2980           // regions. Filter out such entries to avoid failing card table
2981           // verification.
2982           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2983             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2984               *card_ptr = CardTableModRefBS::dirty_card_val();
2985               _dcq.enqueue(card_ptr);
2986             }
2987           }
2988         }
2989         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2990                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2991                hrrs.n_yielded(), r->rem_set()->occupied());
2992         r->rem_set()->clear_locked();
2993       }
2994       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2995     }
2996     _total_humongous++;
2997 
2998     return false;
2999   }
3000 
3001   size_t total_humongous() const { return _total_humongous; }
3002   size_t candidate_humongous() const { return _candidate_humongous; }
3003 
3004   void flush_rem_set_entries() { _dcq.flush(); }
3005 };
3006 
3007 void G1CollectedHeap::register_humongous_regions_with_cset() {
3008   if (!G1EagerReclaimHumongousObjects) {
3009     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3010     return;
3011   }
3012   double time = os::elapsed_counter();
3013 
3014   // Collect reclaim candidate information and register candidates with cset.
3015   RegisterHumongousWithInCSetFastTestClosure cl;
3016   heap_region_iterate(&cl);
3017 
3018   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3019   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3020                                                                   cl.total_humongous(),
3021                                                                   cl.candidate_humongous());
3022   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3023 
3024   // Finally flush all remembered set entries to re-check into the global DCQS.
3025   cl.flush_rem_set_entries();
3026 }
3027 
3028 class VerifyRegionRemSetClosure : public HeapRegionClosure {
3029   public:
3030     bool doHeapRegion(HeapRegion* hr) {
3031       if (!hr->is_archive() && !hr->is_continues_humongous()) {
3032         hr->verify_rem_set();
3033       }
3034       return false;
3035     }
3036 };
3037 
3038 uint G1CollectedHeap::num_task_queues() const {
3039   return _task_queues->size();
3040 }
3041 
3042 #if TASKQUEUE_STATS
3043 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3044   st->print_raw_cr("GC Task Stats");
3045   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3046   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3047 }
3048 
3049 void G1CollectedHeap::print_taskqueue_stats() const {
3050   if (!log_is_enabled(Trace, gc, task, stats)) {
3051     return;
3052   }
3053   Log(gc, task, stats) log;
3054   ResourceMark rm;
3055   outputStream* st = log.trace_stream();
3056 
3057   print_taskqueue_stats_hdr(st);
3058 
3059   TaskQueueStats totals;
3060   const uint n = num_task_queues();
3061   for (uint i = 0; i < n; ++i) {
3062     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3063     totals += task_queue(i)->stats;
3064   }
3065   st->print_raw("tot "); totals.print(st); st->cr();
3066 
3067   DEBUG_ONLY(totals.verify());
3068 }
3069 
3070 void G1CollectedHeap::reset_taskqueue_stats() {
3071   const uint n = num_task_queues();
3072   for (uint i = 0; i < n; ++i) {
3073     task_queue(i)->stats.reset();
3074   }
3075 }
3076 #endif // TASKQUEUE_STATS
3077 
3078 void G1CollectedHeap::wait_for_root_region_scanning() {
3079   double scan_wait_start = os::elapsedTime();
3080   // We have to wait until the CM threads finish scanning the
3081   // root regions as it's the only way to ensure that all the
3082   // objects on them have been correctly scanned before we start
3083   // moving them during the GC.
3084   bool waited = _cm->root_regions()->wait_until_scan_finished();
3085   double wait_time_ms = 0.0;
3086   if (waited) {
3087     double scan_wait_end = os::elapsedTime();
3088     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3089   }
3090   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3091 }
3092 
3093 bool
3094 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3095   assert_at_safepoint(true /* should_be_vm_thread */);
3096   guarantee(!is_gc_active(), "collection is not reentrant");
3097 
3098   if (GCLocker::check_active_before_gc()) {
3099     return false;
3100   }
3101 
3102   _gc_timer_stw->register_gc_start();
3103 
3104   GCIdMark gc_id_mark;
3105   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3106 
3107   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3108   ResourceMark rm;
3109 
3110   g1_policy()->note_gc_start();
3111 
3112   wait_for_root_region_scanning();
3113 
3114   print_heap_before_gc();
3115   print_heap_regions();
3116   trace_heap_before_gc(_gc_tracer_stw);
3117 
3118   _verifier->verify_region_sets_optional();
3119   _verifier->verify_dirty_young_regions();
3120 
3121   // We should not be doing initial mark unless the conc mark thread is running
3122   if (!_cmThread->should_terminate()) {
3123     // This call will decide whether this pause is an initial-mark
3124     // pause. If it is, during_initial_mark_pause() will return true
3125     // for the duration of this pause.
3126     g1_policy()->decide_on_conc_mark_initiation();
3127   }
3128 
3129   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3130   assert(!collector_state()->during_initial_mark_pause() ||
3131           collector_state()->gcs_are_young(), "sanity");
3132 
3133   // We also do not allow mixed GCs during marking.
3134   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3135 
3136   // Record whether this pause is an initial mark. When the current
3137   // thread has completed its logging output and it's safe to signal
3138   // the CM thread, the flag's value in the policy has been reset.
3139   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3140 
3141   // Inner scope for scope based logging, timers, and stats collection
3142   {
3143     EvacuationInfo evacuation_info;
3144 
3145     if (collector_state()->during_initial_mark_pause()) {
3146       // We are about to start a marking cycle, so we increment the
3147       // full collection counter.
3148       increment_old_marking_cycles_started();
3149       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3150     }
3151 
3152     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3153 
3154     GCTraceCPUTime tcpu;
3155 
3156     FormatBuffer<> gc_string("Pause ");
3157     if (collector_state()->during_initial_mark_pause()) {
3158       gc_string.append("Initial Mark");
3159     } else if (collector_state()->gcs_are_young()) {
3160       gc_string.append("Young");
3161     } else {
3162       gc_string.append("Mixed");
3163     }
3164     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3165 
3166     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3167                                                                   workers()->active_workers(),
3168                                                                   Threads::number_of_non_daemon_threads());
3169     workers()->set_active_workers(active_workers);
3170 
3171     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3172     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3173 
3174     // If the secondary_free_list is not empty, append it to the
3175     // free_list. No need to wait for the cleanup operation to finish;
3176     // the region allocation code will check the secondary_free_list
3177     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3178     // set, skip this step so that the region allocation code has to
3179     // get entries from the secondary_free_list.
3180     if (!G1StressConcRegionFreeing) {
3181       append_secondary_free_list_if_not_empty_with_lock();
3182     }
3183 
3184     G1HeapTransition heap_transition(this);
3185     size_t heap_used_bytes_before_gc = used();
3186 
3187     // Don't dynamically change the number of GC threads this early.  A value of
3188     // 0 is used to indicate serial work.  When parallel work is done,
3189     // it will be set.
3190 
3191     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3192       IsGCActiveMark x;
3193 
3194       gc_prologue(false);
3195       increment_total_collections(false /* full gc */);
3196       increment_gc_time_stamp();
3197 
3198       if (VerifyRememberedSets) {
3199         log_info(gc, verify)("[Verifying RemSets before GC]");
3200         VerifyRegionRemSetClosure v_cl;
3201         heap_region_iterate(&v_cl);
3202       }
3203 
3204       _verifier->verify_before_gc();
3205 
3206       _verifier->check_bitmaps("GC Start");
3207 
3208 #if defined(COMPILER2) || INCLUDE_JVMCI
3209       DerivedPointerTable::clear();
3210 #endif
3211 
3212       // Please see comment in g1CollectedHeap.hpp and
3213       // G1CollectedHeap::ref_processing_init() to see how
3214       // reference processing currently works in G1.
3215 
3216       // Enable discovery in the STW reference processor
3217       if (g1_policy()->should_process_references()) {
3218         ref_processor_stw()->enable_discovery();
3219       } else {
3220         ref_processor_stw()->disable_discovery();
3221       }
3222 
3223       {
3224         // We want to temporarily turn off discovery by the
3225         // CM ref processor, if necessary, and turn it back on
3226         // on again later if we do. Using a scoped
3227         // NoRefDiscovery object will do this.
3228         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3229 
3230         // Forget the current alloc region (we might even choose it to be part
3231         // of the collection set!).
3232         _allocator->release_mutator_alloc_region();
3233 
3234         // This timing is only used by the ergonomics to handle our pause target.
3235         // It is unclear why this should not include the full pause. We will
3236         // investigate this in CR 7178365.
3237         //
3238         // Preserving the old comment here if that helps the investigation:
3239         //
3240         // The elapsed time induced by the start time below deliberately elides
3241         // the possible verification above.
3242         double sample_start_time_sec = os::elapsedTime();
3243 
3244         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3245 
3246         if (collector_state()->during_initial_mark_pause()) {
3247           concurrent_mark()->checkpointRootsInitialPre();
3248         }
3249 
3250         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3251 
3252         evacuation_info.set_collectionset_regions(collection_set()->region_length());
3253 
3254         // Make sure the remembered sets are up to date. This needs to be
3255         // done before register_humongous_regions_with_cset(), because the
3256         // remembered sets are used there to choose eager reclaim candidates.
3257         // If the remembered sets are not up to date we might miss some
3258         // entries that need to be handled.
3259         g1_rem_set()->cleanupHRRS();
3260 
3261         register_humongous_regions_with_cset();
3262 
3263         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3264 
3265         _cm->note_start_of_gc();
3266         // We call this after finalize_cset() to
3267         // ensure that the CSet has been finalized.
3268         _cm->verify_no_cset_oops();
3269 
3270         if (_hr_printer.is_active()) {
3271           HeapRegion* hr = collection_set()->head();
3272           while (hr != NULL) {
3273             _hr_printer.cset(hr);
3274             hr = hr->next_in_collection_set();
3275           }
3276         }
3277 
3278         // Initialize the GC alloc regions.
3279         _allocator->init_gc_alloc_regions(evacuation_info);
3280 
3281         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3282         pre_evacuate_collection_set();
3283 
3284         // Actually do the work...
3285         evacuate_collection_set(evacuation_info, &per_thread_states);
3286 
3287         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3288 
3289         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3290         free_collection_set(collection_set()->head(), evacuation_info, surviving_young_words);
3291 
3292         eagerly_reclaim_humongous_regions();
3293 
3294         collection_set()->clear_head();
3295 
3296         record_obj_copy_mem_stats();
3297         _survivor_evac_stats.adjust_desired_plab_sz();
3298         _old_evac_stats.adjust_desired_plab_sz();
3299 
3300         // Start a new incremental collection set for the next pause.
3301         collection_set()->start_incremental_building();
3302 
3303         clear_cset_fast_test();
3304 
3305         guarantee(_eden.length() == 0, "eden should have been cleared");
3306         g1_policy()->transfer_survivors_to_cset(survivor());
3307 
3308         if (evacuation_failed()) {
3309           set_used(recalculate_used());
3310           if (_archive_allocator != NULL) {
3311             _archive_allocator->clear_used();
3312           }
3313           for (uint i = 0; i < ParallelGCThreads; i++) {
3314             if (_evacuation_failed_info_array[i].has_failed()) {
3315               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3316             }
3317           }
3318         } else {
3319           // The "used" of the the collection set have already been subtracted
3320           // when they were freed.  Add in the bytes evacuated.
3321           increase_used(g1_policy()->bytes_copied_during_gc());
3322         }
3323 
3324         if (collector_state()->during_initial_mark_pause()) {
3325           // We have to do this before we notify the CM threads that
3326           // they can start working to make sure that all the
3327           // appropriate initialization is done on the CM object.
3328           concurrent_mark()->checkpointRootsInitialPost();
3329           collector_state()->set_mark_in_progress(true);
3330           // Note that we don't actually trigger the CM thread at
3331           // this point. We do that later when we're sure that
3332           // the current thread has completed its logging output.
3333         }
3334 
3335         allocate_dummy_regions();
3336 
3337         _allocator->init_mutator_alloc_region();
3338 
3339         {
3340           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3341           if (expand_bytes > 0) {
3342             size_t bytes_before = capacity();
3343             // No need for an ergo logging here,
3344             // expansion_amount() does this when it returns a value > 0.
3345             double expand_ms;
3346             if (!expand(expand_bytes, &expand_ms)) {
3347               // We failed to expand the heap. Cannot do anything about it.
3348             }
3349             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3350           }
3351         }
3352 
3353         // We redo the verification but now wrt to the new CSet which
3354         // has just got initialized after the previous CSet was freed.
3355         _cm->verify_no_cset_oops();
3356         _cm->note_end_of_gc();
3357 
3358         // This timing is only used by the ergonomics to handle our pause target.
3359         // It is unclear why this should not include the full pause. We will
3360         // investigate this in CR 7178365.
3361         double sample_end_time_sec = os::elapsedTime();
3362         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3363         size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3364         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3365 
3366         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3367         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3368 
3369         MemoryService::track_memory_usage();
3370 
3371         // In prepare_for_verify() below we'll need to scan the deferred
3372         // update buffers to bring the RSets up-to-date if
3373         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3374         // the update buffers we'll probably need to scan cards on the
3375         // regions we just allocated to (i.e., the GC alloc
3376         // regions). However, during the last GC we called
3377         // set_saved_mark() on all the GC alloc regions, so card
3378         // scanning might skip the [saved_mark_word()...top()] area of
3379         // those regions (i.e., the area we allocated objects into
3380         // during the last GC). But it shouldn't. Given that
3381         // saved_mark_word() is conditional on whether the GC time stamp
3382         // on the region is current or not, by incrementing the GC time
3383         // stamp here we invalidate all the GC time stamps on all the
3384         // regions and saved_mark_word() will simply return top() for
3385         // all the regions. This is a nicer way of ensuring this rather
3386         // than iterating over the regions and fixing them. In fact, the
3387         // GC time stamp increment here also ensures that
3388         // saved_mark_word() will return top() between pauses, i.e.,
3389         // during concurrent refinement. So we don't need the
3390         // is_gc_active() check to decided which top to use when
3391         // scanning cards (see CR 7039627).
3392         increment_gc_time_stamp();
3393 
3394         if (VerifyRememberedSets) {
3395           log_info(gc, verify)("[Verifying RemSets after GC]");
3396           VerifyRegionRemSetClosure v_cl;
3397           heap_region_iterate(&v_cl);
3398         }
3399 
3400         _verifier->verify_after_gc();
3401         _verifier->check_bitmaps("GC End");
3402 
3403         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3404         ref_processor_stw()->verify_no_references_recorded();
3405 
3406         // CM reference discovery will be re-enabled if necessary.
3407       }
3408 
3409 #ifdef TRACESPINNING
3410       ParallelTaskTerminator::print_termination_counts();
3411 #endif
3412 
3413       gc_epilogue(false);
3414     }
3415 
3416     // Print the remainder of the GC log output.
3417     if (evacuation_failed()) {
3418       log_info(gc)("To-space exhausted");
3419     }
3420 
3421     g1_policy()->print_phases();
3422     heap_transition.print();
3423 
3424     // It is not yet to safe to tell the concurrent mark to
3425     // start as we have some optional output below. We don't want the
3426     // output from the concurrent mark thread interfering with this
3427     // logging output either.
3428 
3429     _hrm.verify_optional();
3430     _verifier->verify_region_sets_optional();
3431 
3432     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3433     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3434 
3435     print_heap_after_gc();
3436     print_heap_regions();
3437     trace_heap_after_gc(_gc_tracer_stw);
3438 
3439     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3440     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3441     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3442     // before any GC notifications are raised.
3443     g1mm()->update_sizes();
3444 
3445     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3446     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3447     _gc_timer_stw->register_gc_end();
3448     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3449   }
3450   // It should now be safe to tell the concurrent mark thread to start
3451   // without its logging output interfering with the logging output
3452   // that came from the pause.
3453 
3454   if (should_start_conc_mark) {
3455     // CAUTION: after the doConcurrentMark() call below,
3456     // the concurrent marking thread(s) could be running
3457     // concurrently with us. Make sure that anything after
3458     // this point does not assume that we are the only GC thread
3459     // running. Note: of course, the actual marking work will
3460     // not start until the safepoint itself is released in
3461     // SuspendibleThreadSet::desynchronize().
3462     doConcurrentMark();
3463   }
3464 
3465   return true;
3466 }
3467 
3468 void G1CollectedHeap::remove_self_forwarding_pointers() {
3469   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3470   workers()->run_task(&rsfp_task);
3471 }
3472 
3473 void G1CollectedHeap::restore_after_evac_failure() {
3474   double remove_self_forwards_start = os::elapsedTime();
3475 
3476   remove_self_forwarding_pointers();
3477   _preserved_marks_set.restore(workers());
3478 
3479   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3480 }
3481 
3482 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3483   if (!_evacuation_failed) {
3484     _evacuation_failed = true;
3485   }
3486 
3487   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3488   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3489 }
3490 
3491 bool G1ParEvacuateFollowersClosure::offer_termination() {
3492   G1ParScanThreadState* const pss = par_scan_state();
3493   start_term_time();
3494   const bool res = terminator()->offer_termination();
3495   end_term_time();
3496   return res;
3497 }
3498 
3499 void G1ParEvacuateFollowersClosure::do_void() {
3500   G1ParScanThreadState* const pss = par_scan_state();
3501   pss->trim_queue();
3502   do {
3503     pss->steal_and_trim_queue(queues());
3504   } while (!offer_termination());
3505 }
3506 
3507 class G1ParTask : public AbstractGangTask {
3508 protected:
3509   G1CollectedHeap*         _g1h;
3510   G1ParScanThreadStateSet* _pss;
3511   RefToScanQueueSet*       _queues;
3512   G1RootProcessor*         _root_processor;
3513   ParallelTaskTerminator   _terminator;
3514   uint                     _n_workers;
3515 
3516 public:
3517   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3518     : AbstractGangTask("G1 collection"),
3519       _g1h(g1h),
3520       _pss(per_thread_states),
3521       _queues(task_queues),
3522       _root_processor(root_processor),
3523       _terminator(n_workers, _queues),
3524       _n_workers(n_workers)
3525   {}
3526 
3527   void work(uint worker_id) {
3528     if (worker_id >= _n_workers) return;  // no work needed this round
3529 
3530     double start_sec = os::elapsedTime();
3531     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3532 
3533     {
3534       ResourceMark rm;
3535       HandleMark   hm;
3536 
3537       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3538 
3539       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3540       pss->set_ref_processor(rp);
3541 
3542       double start_strong_roots_sec = os::elapsedTime();
3543 
3544       _root_processor->evacuate_roots(pss->closures(), worker_id);
3545 
3546       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3547 
3548       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3549       // treating the nmethods visited to act as roots for concurrent marking.
3550       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3551       // objects copied by the current evacuation.
3552       size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3553                                                                              pss->closures()->weak_codeblobs(),
3554                                                                              worker_id);
3555 
3556       _pss->add_cards_scanned(worker_id, cards_scanned);
3557 
3558       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3559 
3560       double term_sec = 0.0;
3561       size_t evac_term_attempts = 0;
3562       {
3563         double start = os::elapsedTime();
3564         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3565         evac.do_void();
3566 
3567         evac_term_attempts = evac.term_attempts();
3568         term_sec = evac.term_time();
3569         double elapsed_sec = os::elapsedTime() - start;
3570         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3571         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3572         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3573       }
3574 
3575       assert(pss->queue_is_empty(), "should be empty");
3576 
3577       if (log_is_enabled(Debug, gc, task, stats)) {
3578         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3579         size_t lab_waste;
3580         size_t lab_undo_waste;
3581         pss->waste(lab_waste, lab_undo_waste);
3582         _g1h->print_termination_stats(worker_id,
3583                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3584                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3585                                       term_sec * 1000.0,                          /* evac term time */
3586                                       evac_term_attempts,                         /* evac term attempts */
3587                                       lab_waste,                                  /* alloc buffer waste */
3588                                       lab_undo_waste                              /* undo waste */
3589                                       );
3590       }
3591 
3592       // Close the inner scope so that the ResourceMark and HandleMark
3593       // destructors are executed here and are included as part of the
3594       // "GC Worker Time".
3595     }
3596     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3597   }
3598 };
3599 
3600 void G1CollectedHeap::print_termination_stats_hdr() {
3601   log_debug(gc, task, stats)("GC Termination Stats");
3602   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3603   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3604   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3605 }
3606 
3607 void G1CollectedHeap::print_termination_stats(uint worker_id,
3608                                               double elapsed_ms,
3609                                               double strong_roots_ms,
3610                                               double term_ms,
3611                                               size_t term_attempts,
3612                                               size_t alloc_buffer_waste,
3613                                               size_t undo_waste) const {
3614   log_debug(gc, task, stats)
3615               ("%3d %9.2f %9.2f %6.2f "
3616                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3617                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3618                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3619                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3620                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3621                alloc_buffer_waste * HeapWordSize / K,
3622                undo_waste * HeapWordSize / K);
3623 }
3624 
3625 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3626 private:
3627   BoolObjectClosure* _is_alive;
3628   int _initial_string_table_size;
3629   int _initial_symbol_table_size;
3630 
3631   bool  _process_strings;
3632   int _strings_processed;
3633   int _strings_removed;
3634 
3635   bool  _process_symbols;
3636   int _symbols_processed;
3637   int _symbols_removed;
3638 
3639 public:
3640   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3641     AbstractGangTask("String/Symbol Unlinking"),
3642     _is_alive(is_alive),
3643     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3644     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3645 
3646     _initial_string_table_size = StringTable::the_table()->table_size();
3647     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3648     if (process_strings) {
3649       StringTable::clear_parallel_claimed_index();
3650     }
3651     if (process_symbols) {
3652       SymbolTable::clear_parallel_claimed_index();
3653     }
3654   }
3655 
3656   ~G1StringSymbolTableUnlinkTask() {
3657     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3658               "claim value %d after unlink less than initial string table size %d",
3659               StringTable::parallel_claimed_index(), _initial_string_table_size);
3660     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3661               "claim value %d after unlink less than initial symbol table size %d",
3662               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3663 
3664     log_info(gc, stringtable)(
3665         "Cleaned string and symbol table, "
3666         "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3667         "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3668         strings_processed(), strings_removed(),
3669         symbols_processed(), symbols_removed());
3670   }
3671 
3672   void work(uint worker_id) {
3673     int strings_processed = 0;
3674     int strings_removed = 0;
3675     int symbols_processed = 0;
3676     int symbols_removed = 0;
3677     if (_process_strings) {
3678       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3679       Atomic::add(strings_processed, &_strings_processed);
3680       Atomic::add(strings_removed, &_strings_removed);
3681     }
3682     if (_process_symbols) {
3683       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3684       Atomic::add(symbols_processed, &_symbols_processed);
3685       Atomic::add(symbols_removed, &_symbols_removed);
3686     }
3687   }
3688 
3689   size_t strings_processed() const { return (size_t)_strings_processed; }
3690   size_t strings_removed()   const { return (size_t)_strings_removed; }
3691 
3692   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3693   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3694 };
3695 
3696 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3697 private:
3698   static Monitor* _lock;
3699 
3700   BoolObjectClosure* const _is_alive;
3701   const bool               _unloading_occurred;
3702   const uint               _num_workers;
3703 
3704   // Variables used to claim nmethods.
3705   CompiledMethod* _first_nmethod;
3706   volatile CompiledMethod* _claimed_nmethod;
3707 
3708   // The list of nmethods that need to be processed by the second pass.
3709   volatile CompiledMethod* _postponed_list;
3710   volatile uint            _num_entered_barrier;
3711 
3712  public:
3713   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3714       _is_alive(is_alive),
3715       _unloading_occurred(unloading_occurred),
3716       _num_workers(num_workers),
3717       _first_nmethod(NULL),
3718       _claimed_nmethod(NULL),
3719       _postponed_list(NULL),
3720       _num_entered_barrier(0)
3721   {
3722     CompiledMethod::increase_unloading_clock();
3723     // Get first alive nmethod
3724     CompiledMethodIterator iter = CompiledMethodIterator();
3725     if(iter.next_alive()) {
3726       _first_nmethod = iter.method();
3727     }
3728     _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3729   }
3730 
3731   ~G1CodeCacheUnloadingTask() {
3732     CodeCache::verify_clean_inline_caches();
3733 
3734     CodeCache::set_needs_cache_clean(false);
3735     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3736 
3737     CodeCache::verify_icholder_relocations();
3738   }
3739 
3740  private:
3741   void add_to_postponed_list(CompiledMethod* nm) {
3742       CompiledMethod* old;
3743       do {
3744         old = (CompiledMethod*)_postponed_list;
3745         nm->set_unloading_next(old);
3746       } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3747   }
3748 
3749   void clean_nmethod(CompiledMethod* nm) {
3750     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3751 
3752     if (postponed) {
3753       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3754       add_to_postponed_list(nm);
3755     }
3756 
3757     // Mark that this thread has been cleaned/unloaded.
3758     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3759     nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3760   }
3761 
3762   void clean_nmethod_postponed(CompiledMethod* nm) {
3763     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3764   }
3765 
3766   static const int MaxClaimNmethods = 16;
3767 
3768   void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3769     CompiledMethod* first;
3770     CompiledMethodIterator last;
3771 
3772     do {
3773       *num_claimed_nmethods = 0;
3774 
3775       first = (CompiledMethod*)_claimed_nmethod;
3776       last = CompiledMethodIterator(first);
3777 
3778       if (first != NULL) {
3779 
3780         for (int i = 0; i < MaxClaimNmethods; i++) {
3781           if (!last.next_alive()) {
3782             break;
3783           }
3784           claimed_nmethods[i] = last.method();
3785           (*num_claimed_nmethods)++;
3786         }
3787       }
3788 
3789     } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3790   }
3791 
3792   CompiledMethod* claim_postponed_nmethod() {
3793     CompiledMethod* claim;
3794     CompiledMethod* next;
3795 
3796     do {
3797       claim = (CompiledMethod*)_postponed_list;
3798       if (claim == NULL) {
3799         return NULL;
3800       }
3801 
3802       next = claim->unloading_next();
3803 
3804     } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3805 
3806     return claim;
3807   }
3808 
3809  public:
3810   // Mark that we're done with the first pass of nmethod cleaning.
3811   void barrier_mark(uint worker_id) {
3812     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3813     _num_entered_barrier++;
3814     if (_num_entered_barrier == _num_workers) {
3815       ml.notify_all();
3816     }
3817   }
3818 
3819   // See if we have to wait for the other workers to
3820   // finish their first-pass nmethod cleaning work.
3821   void barrier_wait(uint worker_id) {
3822     if (_num_entered_barrier < _num_workers) {
3823       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3824       while (_num_entered_barrier < _num_workers) {
3825           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3826       }
3827     }
3828   }
3829 
3830   // Cleaning and unloading of nmethods. Some work has to be postponed
3831   // to the second pass, when we know which nmethods survive.
3832   void work_first_pass(uint worker_id) {
3833     // The first nmethods is claimed by the first worker.
3834     if (worker_id == 0 && _first_nmethod != NULL) {
3835       clean_nmethod(_first_nmethod);
3836       _first_nmethod = NULL;
3837     }
3838 
3839     int num_claimed_nmethods;
3840     CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3841 
3842     while (true) {
3843       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3844 
3845       if (num_claimed_nmethods == 0) {
3846         break;
3847       }
3848 
3849       for (int i = 0; i < num_claimed_nmethods; i++) {
3850         clean_nmethod(claimed_nmethods[i]);
3851       }
3852     }
3853   }
3854 
3855   void work_second_pass(uint worker_id) {
3856     CompiledMethod* nm;
3857     // Take care of postponed nmethods.
3858     while ((nm = claim_postponed_nmethod()) != NULL) {
3859       clean_nmethod_postponed(nm);
3860     }
3861   }
3862 };
3863 
3864 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3865 
3866 class G1KlassCleaningTask : public StackObj {
3867   BoolObjectClosure*                      _is_alive;
3868   volatile jint                           _clean_klass_tree_claimed;
3869   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3870 
3871  public:
3872   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3873       _is_alive(is_alive),
3874       _clean_klass_tree_claimed(0),
3875       _klass_iterator() {
3876   }
3877 
3878  private:
3879   bool claim_clean_klass_tree_task() {
3880     if (_clean_klass_tree_claimed) {
3881       return false;
3882     }
3883 
3884     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3885   }
3886 
3887   InstanceKlass* claim_next_klass() {
3888     Klass* klass;
3889     do {
3890       klass =_klass_iterator.next_klass();
3891     } while (klass != NULL && !klass->is_instance_klass());
3892 
3893     // this can be null so don't call InstanceKlass::cast
3894     return static_cast<InstanceKlass*>(klass);
3895   }
3896 
3897 public:
3898 
3899   void clean_klass(InstanceKlass* ik) {
3900     ik->clean_weak_instanceklass_links(_is_alive);
3901   }
3902 
3903   void work() {
3904     ResourceMark rm;
3905 
3906     // One worker will clean the subklass/sibling klass tree.
3907     if (claim_clean_klass_tree_task()) {
3908       Klass::clean_subklass_tree(_is_alive);
3909     }
3910 
3911     // All workers will help cleaning the classes,
3912     InstanceKlass* klass;
3913     while ((klass = claim_next_klass()) != NULL) {
3914       clean_klass(klass);
3915     }
3916   }
3917 };
3918 
3919 // To minimize the remark pause times, the tasks below are done in parallel.
3920 class G1ParallelCleaningTask : public AbstractGangTask {
3921 private:
3922   G1StringSymbolTableUnlinkTask _string_symbol_task;
3923   G1CodeCacheUnloadingTask      _code_cache_task;
3924   G1KlassCleaningTask           _klass_cleaning_task;
3925 
3926 public:
3927   // The constructor is run in the VMThread.
3928   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
3929       AbstractGangTask("Parallel Cleaning"),
3930       _string_symbol_task(is_alive, process_strings, process_symbols),
3931       _code_cache_task(num_workers, is_alive, unloading_occurred),
3932       _klass_cleaning_task(is_alive) {
3933   }
3934 
3935   // The parallel work done by all worker threads.
3936   void work(uint worker_id) {
3937     // Do first pass of code cache cleaning.
3938     _code_cache_task.work_first_pass(worker_id);
3939 
3940     // Let the threads mark that the first pass is done.
3941     _code_cache_task.barrier_mark(worker_id);
3942 
3943     // Clean the Strings and Symbols.
3944     _string_symbol_task.work(worker_id);
3945 
3946     // Wait for all workers to finish the first code cache cleaning pass.
3947     _code_cache_task.barrier_wait(worker_id);
3948 
3949     // Do the second code cache cleaning work, which realize on
3950     // the liveness information gathered during the first pass.
3951     _code_cache_task.work_second_pass(worker_id);
3952 
3953     // Clean all klasses that were not unloaded.
3954     _klass_cleaning_task.work();
3955   }
3956 };
3957 
3958 
3959 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
3960                                         bool process_strings,
3961                                         bool process_symbols,
3962                                         bool class_unloading_occurred) {
3963   uint n_workers = workers()->active_workers();
3964 
3965   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
3966                                         n_workers, class_unloading_occurred);
3967   workers()->run_task(&g1_unlink_task);
3968 }
3969 
3970 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
3971                                                      bool process_strings, bool process_symbols) {
3972   { // Timing scope
3973     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
3974     workers()->run_task(&g1_unlink_task);
3975   }
3976 }
3977 
3978 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3979  private:
3980   DirtyCardQueueSet* _queue;
3981   G1CollectedHeap* _g1h;
3982  public:
3983   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3984     _queue(queue), _g1h(g1h) { }
3985 
3986   virtual void work(uint worker_id) {
3987     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3988     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3989 
3990     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3991     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3992 
3993     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3994   }
3995 };
3996 
3997 void G1CollectedHeap::redirty_logged_cards() {
3998   double redirty_logged_cards_start = os::elapsedTime();
3999 
4000   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4001   dirty_card_queue_set().reset_for_par_iteration();
4002   workers()->run_task(&redirty_task);
4003 
4004   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4005   dcq.merge_bufferlists(&dirty_card_queue_set());
4006   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4007 
4008   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4009 }
4010 
4011 // Weak Reference Processing support
4012 
4013 // An always "is_alive" closure that is used to preserve referents.
4014 // If the object is non-null then it's alive.  Used in the preservation
4015 // of referent objects that are pointed to by reference objects
4016 // discovered by the CM ref processor.
4017 class G1AlwaysAliveClosure: public BoolObjectClosure {
4018   G1CollectedHeap* _g1;
4019 public:
4020   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4021   bool do_object_b(oop p) {
4022     if (p != NULL) {
4023       return true;
4024     }
4025     return false;
4026   }
4027 };
4028 
4029 bool G1STWIsAliveClosure::do_object_b(oop p) {
4030   // An object is reachable if it is outside the collection set,
4031   // or is inside and copied.
4032   return !_g1->is_in_cset(p) || p->is_forwarded();
4033 }
4034 
4035 // Non Copying Keep Alive closure
4036 class G1KeepAliveClosure: public OopClosure {
4037   G1CollectedHeap* _g1;
4038 public:
4039   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4040   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4041   void do_oop(oop* p) {
4042     oop obj = *p;
4043     assert(obj != NULL, "the caller should have filtered out NULL values");
4044 
4045     const InCSetState cset_state = _g1->in_cset_state(obj);
4046     if (!cset_state.is_in_cset_or_humongous()) {
4047       return;
4048     }
4049     if (cset_state.is_in_cset()) {
4050       assert( obj->is_forwarded(), "invariant" );
4051       *p = obj->forwardee();
4052     } else {
4053       assert(!obj->is_forwarded(), "invariant" );
4054       assert(cset_state.is_humongous(),
4055              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4056       _g1->set_humongous_is_live(obj);
4057     }
4058   }
4059 };
4060 
4061 // Copying Keep Alive closure - can be called from both
4062 // serial and parallel code as long as different worker
4063 // threads utilize different G1ParScanThreadState instances
4064 // and different queues.
4065 
4066 class G1CopyingKeepAliveClosure: public OopClosure {
4067   G1CollectedHeap*         _g1h;
4068   OopClosure*              _copy_non_heap_obj_cl;
4069   G1ParScanThreadState*    _par_scan_state;
4070 
4071 public:
4072   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4073                             OopClosure* non_heap_obj_cl,
4074                             G1ParScanThreadState* pss):
4075     _g1h(g1h),
4076     _copy_non_heap_obj_cl(non_heap_obj_cl),
4077     _par_scan_state(pss)
4078   {}
4079 
4080   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4081   virtual void do_oop(      oop* p) { do_oop_work(p); }
4082 
4083   template <class T> void do_oop_work(T* p) {
4084     oop obj = oopDesc::load_decode_heap_oop(p);
4085 
4086     if (_g1h->is_in_cset_or_humongous(obj)) {
4087       // If the referent object has been forwarded (either copied
4088       // to a new location or to itself in the event of an
4089       // evacuation failure) then we need to update the reference
4090       // field and, if both reference and referent are in the G1
4091       // heap, update the RSet for the referent.
4092       //
4093       // If the referent has not been forwarded then we have to keep
4094       // it alive by policy. Therefore we have copy the referent.
4095       //
4096       // If the reference field is in the G1 heap then we can push
4097       // on the PSS queue. When the queue is drained (after each
4098       // phase of reference processing) the object and it's followers
4099       // will be copied, the reference field set to point to the
4100       // new location, and the RSet updated. Otherwise we need to
4101       // use the the non-heap or metadata closures directly to copy
4102       // the referent object and update the pointer, while avoiding
4103       // updating the RSet.
4104 
4105       if (_g1h->is_in_g1_reserved(p)) {
4106         _par_scan_state->push_on_queue(p);
4107       } else {
4108         assert(!Metaspace::contains((const void*)p),
4109                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4110         _copy_non_heap_obj_cl->do_oop(p);
4111       }
4112     }
4113   }
4114 };
4115 
4116 // Serial drain queue closure. Called as the 'complete_gc'
4117 // closure for each discovered list in some of the
4118 // reference processing phases.
4119 
4120 class G1STWDrainQueueClosure: public VoidClosure {
4121 protected:
4122   G1CollectedHeap* _g1h;
4123   G1ParScanThreadState* _par_scan_state;
4124 
4125   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4126 
4127 public:
4128   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4129     _g1h(g1h),
4130     _par_scan_state(pss)
4131   { }
4132 
4133   void do_void() {
4134     G1ParScanThreadState* const pss = par_scan_state();
4135     pss->trim_queue();
4136   }
4137 };
4138 
4139 // Parallel Reference Processing closures
4140 
4141 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4142 // processing during G1 evacuation pauses.
4143 
4144 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4145 private:
4146   G1CollectedHeap*          _g1h;
4147   G1ParScanThreadStateSet*  _pss;
4148   RefToScanQueueSet*        _queues;
4149   WorkGang*                 _workers;
4150   uint                      _active_workers;
4151 
4152 public:
4153   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4154                            G1ParScanThreadStateSet* per_thread_states,
4155                            WorkGang* workers,
4156                            RefToScanQueueSet *task_queues,
4157                            uint n_workers) :
4158     _g1h(g1h),
4159     _pss(per_thread_states),
4160     _queues(task_queues),
4161     _workers(workers),
4162     _active_workers(n_workers)
4163   {
4164     g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4165   }
4166 
4167   // Executes the given task using concurrent marking worker threads.
4168   virtual void execute(ProcessTask& task);
4169   virtual void execute(EnqueueTask& task);
4170 };
4171 
4172 // Gang task for possibly parallel reference processing
4173 
4174 class G1STWRefProcTaskProxy: public AbstractGangTask {
4175   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4176   ProcessTask&     _proc_task;
4177   G1CollectedHeap* _g1h;
4178   G1ParScanThreadStateSet* _pss;
4179   RefToScanQueueSet* _task_queues;
4180   ParallelTaskTerminator* _terminator;
4181 
4182 public:
4183   G1STWRefProcTaskProxy(ProcessTask& proc_task,
4184                         G1CollectedHeap* g1h,
4185                         G1ParScanThreadStateSet* per_thread_states,
4186                         RefToScanQueueSet *task_queues,
4187                         ParallelTaskTerminator* terminator) :
4188     AbstractGangTask("Process reference objects in parallel"),
4189     _proc_task(proc_task),
4190     _g1h(g1h),
4191     _pss(per_thread_states),
4192     _task_queues(task_queues),
4193     _terminator(terminator)
4194   {}
4195 
4196   virtual void work(uint worker_id) {
4197     // The reference processing task executed by a single worker.
4198     ResourceMark rm;
4199     HandleMark   hm;
4200 
4201     G1STWIsAliveClosure is_alive(_g1h);
4202 
4203     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4204     pss->set_ref_processor(NULL);
4205 
4206     // Keep alive closure.
4207     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4208 
4209     // Complete GC closure
4210     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4211 
4212     // Call the reference processing task's work routine.
4213     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4214 
4215     // Note we cannot assert that the refs array is empty here as not all
4216     // of the processing tasks (specifically phase2 - pp2_work) execute
4217     // the complete_gc closure (which ordinarily would drain the queue) so
4218     // the queue may not be empty.
4219   }
4220 };
4221 
4222 // Driver routine for parallel reference processing.
4223 // Creates an instance of the ref processing gang
4224 // task and has the worker threads execute it.
4225 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4226   assert(_workers != NULL, "Need parallel worker threads.");
4227 
4228   ParallelTaskTerminator terminator(_active_workers, _queues);
4229   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4230 
4231   _workers->run_task(&proc_task_proxy);
4232 }
4233 
4234 // Gang task for parallel reference enqueueing.
4235 
4236 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4237   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4238   EnqueueTask& _enq_task;
4239 
4240 public:
4241   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4242     AbstractGangTask("Enqueue reference objects in parallel"),
4243     _enq_task(enq_task)
4244   { }
4245 
4246   virtual void work(uint worker_id) {
4247     _enq_task.work(worker_id);
4248   }
4249 };
4250 
4251 // Driver routine for parallel reference enqueueing.
4252 // Creates an instance of the ref enqueueing gang
4253 // task and has the worker threads execute it.
4254 
4255 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4256   assert(_workers != NULL, "Need parallel worker threads.");
4257 
4258   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4259 
4260   _workers->run_task(&enq_task_proxy);
4261 }
4262 
4263 // End of weak reference support closures
4264 
4265 // Abstract task used to preserve (i.e. copy) any referent objects
4266 // that are in the collection set and are pointed to by reference
4267 // objects discovered by the CM ref processor.
4268 
4269 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4270 protected:
4271   G1CollectedHeap*         _g1h;
4272   G1ParScanThreadStateSet* _pss;
4273   RefToScanQueueSet*       _queues;
4274   ParallelTaskTerminator   _terminator;
4275   uint                     _n_workers;
4276 
4277 public:
4278   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4279     AbstractGangTask("ParPreserveCMReferents"),
4280     _g1h(g1h),
4281     _pss(per_thread_states),
4282     _queues(task_queues),
4283     _terminator(workers, _queues),
4284     _n_workers(workers)
4285   {
4286     g1h->ref_processor_cm()->set_active_mt_degree(workers);
4287   }
4288 
4289   void work(uint worker_id) {
4290     G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4291 
4292     ResourceMark rm;
4293     HandleMark   hm;
4294 
4295     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4296     pss->set_ref_processor(NULL);
4297     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4298 
4299     // Is alive closure
4300     G1AlwaysAliveClosure always_alive(_g1h);
4301 
4302     // Copying keep alive closure. Applied to referent objects that need
4303     // to be copied.
4304     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4305 
4306     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4307 
4308     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4309     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4310 
4311     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4312     // So this must be true - but assert just in case someone decides to
4313     // change the worker ids.
4314     assert(worker_id < limit, "sanity");
4315     assert(!rp->discovery_is_atomic(), "check this code");
4316 
4317     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4318     for (uint idx = worker_id; idx < limit; idx += stride) {
4319       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4320 
4321       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4322       while (iter.has_next()) {
4323         // Since discovery is not atomic for the CM ref processor, we
4324         // can see some null referent objects.
4325         iter.load_ptrs(DEBUG_ONLY(true));
4326         oop ref = iter.obj();
4327 
4328         // This will filter nulls.
4329         if (iter.is_referent_alive()) {
4330           iter.make_referent_alive();
4331         }
4332         iter.move_to_next();
4333       }
4334     }
4335 
4336     // Drain the queue - which may cause stealing
4337     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4338     drain_queue.do_void();
4339     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4340     assert(pss->queue_is_empty(), "should be");
4341   }
4342 };
4343 
4344 void G1CollectedHeap::process_weak_jni_handles() {
4345   double ref_proc_start = os::elapsedTime();
4346 
4347   G1STWIsAliveClosure is_alive(this);
4348   G1KeepAliveClosure keep_alive(this);
4349   JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4350 
4351   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4352   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4353 }
4354 
4355 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4356   // Any reference objects, in the collection set, that were 'discovered'
4357   // by the CM ref processor should have already been copied (either by
4358   // applying the external root copy closure to the discovered lists, or
4359   // by following an RSet entry).
4360   //
4361   // But some of the referents, that are in the collection set, that these
4362   // reference objects point to may not have been copied: the STW ref
4363   // processor would have seen that the reference object had already
4364   // been 'discovered' and would have skipped discovering the reference,
4365   // but would not have treated the reference object as a regular oop.
4366   // As a result the copy closure would not have been applied to the
4367   // referent object.
4368   //
4369   // We need to explicitly copy these referent objects - the references
4370   // will be processed at the end of remarking.
4371   //
4372   // We also need to do this copying before we process the reference
4373   // objects discovered by the STW ref processor in case one of these
4374   // referents points to another object which is also referenced by an
4375   // object discovered by the STW ref processor.
4376   double preserve_cm_referents_time = 0.0;
4377 
4378   // To avoid spawning task when there is no work to do, check that
4379   // a concurrent cycle is active and that some references have been
4380   // discovered.
4381   if (concurrent_mark()->cmThread()->during_cycle() &&
4382       ref_processor_cm()->has_discovered_references()) {
4383     double preserve_cm_referents_start = os::elapsedTime();
4384     uint no_of_gc_workers = workers()->active_workers();
4385     G1ParPreserveCMReferentsTask keep_cm_referents(this,
4386                                                    per_thread_states,
4387                                                    no_of_gc_workers,
4388                                                    _task_queues);
4389     workers()->run_task(&keep_cm_referents);
4390     preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4391   }
4392 
4393   g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4394 }
4395 
4396 // Weak Reference processing during an evacuation pause (part 1).
4397 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4398   double ref_proc_start = os::elapsedTime();
4399 
4400   ReferenceProcessor* rp = _ref_processor_stw;
4401   assert(rp->discovery_enabled(), "should have been enabled");
4402 
4403   // Closure to test whether a referent is alive.
4404   G1STWIsAliveClosure is_alive(this);
4405 
4406   // Even when parallel reference processing is enabled, the processing
4407   // of JNI refs is serial and performed serially by the current thread
4408   // rather than by a worker. The following PSS will be used for processing
4409   // JNI refs.
4410 
4411   // Use only a single queue for this PSS.
4412   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4413   pss->set_ref_processor(NULL);
4414   assert(pss->queue_is_empty(), "pre-condition");
4415 
4416   // Keep alive closure.
4417   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4418 
4419   // Serial Complete GC closure
4420   G1STWDrainQueueClosure drain_queue(this, pss);
4421 
4422   // Setup the soft refs policy...
4423   rp->setup_policy(false);
4424 
4425   ReferenceProcessorStats stats;
4426   if (!rp->processing_is_mt()) {
4427     // Serial reference processing...
4428     stats = rp->process_discovered_references(&is_alive,
4429                                               &keep_alive,
4430                                               &drain_queue,
4431                                               NULL,
4432                                               _gc_timer_stw);
4433   } else {
4434     uint no_of_gc_workers = workers()->active_workers();
4435 
4436     // Parallel reference processing
4437     assert(no_of_gc_workers <= rp->max_num_q(),
4438            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4439            no_of_gc_workers,  rp->max_num_q());
4440 
4441     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4442     stats = rp->process_discovered_references(&is_alive,
4443                                               &keep_alive,
4444                                               &drain_queue,
4445                                               &par_task_executor,
4446                                               _gc_timer_stw);
4447   }
4448 
4449   _gc_tracer_stw->report_gc_reference_stats(stats);
4450 
4451   // We have completed copying any necessary live referent objects.
4452   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4453 
4454   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4455   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4456 }
4457 
4458 // Weak Reference processing during an evacuation pause (part 2).
4459 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4460   double ref_enq_start = os::elapsedTime();
4461 
4462   ReferenceProcessor* rp = _ref_processor_stw;
4463   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4464 
4465   // Now enqueue any remaining on the discovered lists on to
4466   // the pending list.
4467   if (!rp->processing_is_mt()) {
4468     // Serial reference processing...
4469     rp->enqueue_discovered_references();
4470   } else {
4471     // Parallel reference enqueueing
4472 
4473     uint n_workers = workers()->active_workers();
4474 
4475     assert(n_workers <= rp->max_num_q(),
4476            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4477            n_workers,  rp->max_num_q());
4478 
4479     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4480     rp->enqueue_discovered_references(&par_task_executor);
4481   }
4482 
4483   rp->verify_no_references_recorded();
4484   assert(!rp->discovery_enabled(), "should have been disabled");
4485 
4486   // FIXME
4487   // CM's reference processing also cleans up the string and symbol tables.
4488   // Should we do that here also? We could, but it is a serial operation
4489   // and could significantly increase the pause time.
4490 
4491   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4492   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4493 }
4494 
4495 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4496   double merge_pss_time_start = os::elapsedTime();
4497   per_thread_states->flush();
4498   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4499 }
4500 
4501 void G1CollectedHeap::pre_evacuate_collection_set() {
4502   _expand_heap_after_alloc_failure = true;
4503   _evacuation_failed = false;
4504 
4505   // Disable the hot card cache.
4506   _hot_card_cache->reset_hot_cache_claimed_index();
4507   _hot_card_cache->set_use_cache(false);
4508 
4509   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4510   _preserved_marks_set.assert_empty();
4511 }
4512 
4513 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4514   // Should G1EvacuationFailureALot be in effect for this GC?
4515   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4516 
4517   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4518   double start_par_time_sec = os::elapsedTime();
4519   double end_par_time_sec;
4520 
4521   {
4522     const uint n_workers = workers()->active_workers();
4523     G1RootProcessor root_processor(this, n_workers);
4524     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4525     // InitialMark needs claim bits to keep track of the marked-through CLDs.
4526     if (collector_state()->during_initial_mark_pause()) {
4527       ClassLoaderDataGraph::clear_claimed_marks();
4528     }
4529 
4530     print_termination_stats_hdr();
4531 
4532     workers()->run_task(&g1_par_task);
4533     end_par_time_sec = os::elapsedTime();
4534 
4535     // Closing the inner scope will execute the destructor
4536     // for the G1RootProcessor object. We record the current
4537     // elapsed time before closing the scope so that time
4538     // taken for the destructor is NOT included in the
4539     // reported parallel time.
4540   }
4541 
4542   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4543 
4544   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4545   phase_times->record_par_time(par_time_ms);
4546 
4547   double code_root_fixup_time_ms =
4548         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4549   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4550 }
4551 
4552 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4553   // Process any discovered reference objects - we have
4554   // to do this _before_ we retire the GC alloc regions
4555   // as we may have to copy some 'reachable' referent
4556   // objects (and their reachable sub-graphs) that were
4557   // not copied during the pause.
4558   if (g1_policy()->should_process_references()) {
4559     preserve_cm_referents(per_thread_states);
4560     process_discovered_references(per_thread_states);
4561   } else {
4562     ref_processor_stw()->verify_no_references_recorded();
4563     process_weak_jni_handles();
4564   }
4565 
4566   if (G1StringDedup::is_enabled()) {
4567     double fixup_start = os::elapsedTime();
4568 
4569     G1STWIsAliveClosure is_alive(this);
4570     G1KeepAliveClosure keep_alive(this);
4571     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4572 
4573     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4574     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4575   }
4576 
4577   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4578 
4579   if (evacuation_failed()) {
4580     restore_after_evac_failure();
4581 
4582     // Reset the G1EvacuationFailureALot counters and flags
4583     // Note: the values are reset only when an actual
4584     // evacuation failure occurs.
4585     NOT_PRODUCT(reset_evacuation_should_fail();)
4586   }
4587 
4588   _preserved_marks_set.assert_empty();
4589 
4590   // Enqueue any remaining references remaining on the STW
4591   // reference processor's discovered lists. We need to do
4592   // this after the card table is cleaned (and verified) as
4593   // the act of enqueueing entries on to the pending list
4594   // will log these updates (and dirty their associated
4595   // cards). We need these updates logged to update any
4596   // RSets.
4597   if (g1_policy()->should_process_references()) {
4598     enqueue_discovered_references(per_thread_states);
4599   } else {
4600     g1_policy()->phase_times()->record_ref_enq_time(0);
4601   }
4602 
4603   _allocator->release_gc_alloc_regions(evacuation_info);
4604 
4605   merge_per_thread_state_info(per_thread_states);
4606 
4607   // Reset and re-enable the hot card cache.
4608   // Note the counts for the cards in the regions in the
4609   // collection set are reset when the collection set is freed.
4610   _hot_card_cache->reset_hot_cache();
4611   _hot_card_cache->set_use_cache(true);
4612 
4613   purge_code_root_memory();
4614 
4615   redirty_logged_cards();
4616 #if defined(COMPILER2) || INCLUDE_JVMCI
4617   DerivedPointerTable::update_pointers();
4618 #endif
4619 }
4620 
4621 void G1CollectedHeap::record_obj_copy_mem_stats() {
4622   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4623 
4624   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4625                                                create_g1_evac_summary(&_old_evac_stats));
4626 }
4627 
4628 void G1CollectedHeap::free_region(HeapRegion* hr,
4629                                   FreeRegionList* free_list,
4630                                   bool par,
4631                                   bool locked) {
4632   assert(!hr->is_free(), "the region should not be free");
4633   assert(!hr->is_empty(), "the region should not be empty");
4634   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4635   assert(free_list != NULL, "pre-condition");
4636 
4637   if (G1VerifyBitmaps) {
4638     MemRegion mr(hr->bottom(), hr->end());
4639     concurrent_mark()->clearRangePrevBitmap(mr);
4640   }
4641 
4642   // Clear the card counts for this region.
4643   // Note: we only need to do this if the region is not young
4644   // (since we don't refine cards in young regions).
4645   if (!hr->is_young()) {
4646     _hot_card_cache->reset_card_counts(hr);
4647   }
4648   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
4649   free_list->add_ordered(hr);
4650 }
4651 
4652 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4653                                             FreeRegionList* free_list,
4654                                             bool par) {
4655   assert(hr->is_humongous(), "this is only for humongous regions");
4656   assert(free_list != NULL, "pre-condition");
4657   hr->clear_humongous();
4658   free_region(hr, free_list, par);
4659 }
4660 
4661 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4662                                            const uint humongous_regions_removed) {
4663   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4664     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4665     _old_set.bulk_remove(old_regions_removed);
4666     _humongous_set.bulk_remove(humongous_regions_removed);
4667   }
4668 
4669 }
4670 
4671 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4672   assert(list != NULL, "list can't be null");
4673   if (!list->is_empty()) {
4674     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4675     _hrm.insert_list_into_free_list(list);
4676   }
4677 }
4678 
4679 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4680   decrease_used(bytes);
4681 }
4682 
4683 class G1ParScrubRemSetTask: public AbstractGangTask {
4684 protected:
4685   G1RemSet* _g1rs;
4686   HeapRegionClaimer _hrclaimer;
4687 
4688 public:
4689   G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4690     AbstractGangTask("G1 ScrubRS"),
4691     _g1rs(g1_rs),
4692     _hrclaimer(num_workers) {
4693   }
4694 
4695   void work(uint worker_id) {
4696     _g1rs->scrub(worker_id, &_hrclaimer);
4697   }
4698 };
4699 
4700 void G1CollectedHeap::scrub_rem_set() {
4701   uint num_workers = workers()->active_workers();
4702   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4703   workers()->run_task(&g1_par_scrub_rs_task);
4704 }
4705 
4706 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4707   size_t pre_used = 0;
4708   FreeRegionList local_free_list("Local List for CSet Freeing");
4709 
4710   double young_time_ms     = 0.0;
4711   double non_young_time_ms = 0.0;
4712 
4713   _eden.clear();
4714 
4715   G1Policy* policy = g1_policy();
4716 
4717   double start_sec = os::elapsedTime();
4718   bool non_young = true;
4719 
4720   HeapRegion* cur = cs_head;
4721   int age_bound = -1;
4722   size_t rs_lengths = 0;
4723 
4724   while (cur != NULL) {
4725     assert(!is_on_master_free_list(cur), "sanity");
4726     if (non_young) {
4727       if (cur->is_young()) {
4728         double end_sec = os::elapsedTime();
4729         double elapsed_ms = (end_sec - start_sec) * 1000.0;
4730         non_young_time_ms += elapsed_ms;
4731 
4732         start_sec = os::elapsedTime();
4733         non_young = false;
4734       }
4735     } else {
4736       if (!cur->is_young()) {
4737         double end_sec = os::elapsedTime();
4738         double elapsed_ms = (end_sec - start_sec) * 1000.0;
4739         young_time_ms += elapsed_ms;
4740 
4741         start_sec = os::elapsedTime();
4742         non_young = true;
4743       }
4744     }
4745 
4746     rs_lengths += cur->rem_set()->occupied_locked();
4747 
4748     HeapRegion* next = cur->next_in_collection_set();
4749     assert(cur->in_collection_set(), "bad CS");
4750     cur->set_next_in_collection_set(NULL);
4751     clear_in_cset(cur);
4752 
4753     if (cur->is_young()) {
4754       int index = cur->young_index_in_cset();
4755       assert(index != -1, "invariant");
4756       assert((uint) index < collection_set()->young_region_length(), "invariant");
4757       size_t words_survived = surviving_young_words[index];
4758       cur->record_surv_words_in_group(words_survived);
4759 
4760     } else {
4761       int index = cur->young_index_in_cset();
4762       assert(index == -1, "invariant");
4763     }
4764 
4765     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4766             (!cur->is_young() && cur->young_index_in_cset() == -1),
4767             "invariant" );
4768 
4769     if (!cur->evacuation_failed()) {
4770       MemRegion used_mr = cur->used_region();
4771 
4772       // And the region is empty.
4773       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
4774       pre_used += cur->used();
4775       free_region(cur, &local_free_list, false /* par */, true /* locked */);
4776     } else {
4777       cur->uninstall_surv_rate_group();
4778       if (cur->is_young()) {
4779         cur->set_young_index_in_cset(-1);
4780       }
4781       cur->set_evacuation_failed(false);
4782       // When moving a young gen region to old gen, we "allocate" that whole region
4783       // there. This is in addition to any already evacuated objects. Notify the
4784       // policy about that.
4785       // Old gen regions do not cause an additional allocation: both the objects
4786       // still in the region and the ones already moved are accounted for elsewhere.
4787       if (cur->is_young()) {
4788         policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
4789       }
4790       // The region is now considered to be old.
4791       cur->set_old();
4792       // Do some allocation statistics accounting. Regions that failed evacuation
4793       // are always made old, so there is no need to update anything in the young
4794       // gen statistics, but we need to update old gen statistics.
4795       size_t used_words = cur->marked_bytes() / HeapWordSize;
4796       _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
4797       _old_set.add(cur);
4798       evacuation_info.increment_collectionset_used_after(cur->used());
4799     }
4800     cur = next;
4801   }
4802 
4803   evacuation_info.set_regions_freed(local_free_list.length());
4804   policy->record_max_rs_lengths(rs_lengths);
4805   policy->cset_regions_freed();
4806 
4807   double end_sec = os::elapsedTime();
4808   double elapsed_ms = (end_sec - start_sec) * 1000.0;
4809 
4810   if (non_young) {
4811     non_young_time_ms += elapsed_ms;
4812   } else {
4813     young_time_ms += elapsed_ms;
4814   }
4815 
4816   prepend_to_freelist(&local_free_list);
4817   decrement_summary_bytes(pre_used);
4818   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
4819   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
4820 }
4821 
4822 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4823  private:
4824   FreeRegionList* _free_region_list;
4825   HeapRegionSet* _proxy_set;
4826   uint _humongous_regions_removed;
4827   size_t _freed_bytes;
4828  public:
4829 
4830   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4831     _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4832   }
4833 
4834   virtual bool doHeapRegion(HeapRegion* r) {
4835     if (!r->is_starts_humongous()) {
4836       return false;
4837     }
4838 
4839     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4840 
4841     oop obj = (oop)r->bottom();
4842     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4843 
4844     // The following checks whether the humongous object is live are sufficient.
4845     // The main additional check (in addition to having a reference from the roots
4846     // or the young gen) is whether the humongous object has a remembered set entry.
4847     //
4848     // A humongous object cannot be live if there is no remembered set for it
4849     // because:
4850     // - there can be no references from within humongous starts regions referencing
4851     // the object because we never allocate other objects into them.
4852     // (I.e. there are no intra-region references that may be missed by the
4853     // remembered set)
4854     // - as soon there is a remembered set entry to the humongous starts region
4855     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4856     // until the end of a concurrent mark.
4857     //
4858     // It is not required to check whether the object has been found dead by marking
4859     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4860     // all objects allocated during that time are considered live.
4861     // SATB marking is even more conservative than the remembered set.
4862     // So if at this point in the collection there is no remembered set entry,
4863     // nobody has a reference to it.
4864     // At the start of collection we flush all refinement logs, and remembered sets
4865     // are completely up-to-date wrt to references to the humongous object.
4866     //
4867     // Other implementation considerations:
4868     // - never consider object arrays at this time because they would pose
4869     // considerable effort for cleaning up the the remembered sets. This is
4870     // required because stale remembered sets might reference locations that
4871     // are currently allocated into.
4872     uint region_idx = r->hrm_index();
4873     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4874         !r->rem_set()->is_empty()) {
4875       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",
4876                                region_idx,
4877                                (size_t)obj->size() * HeapWordSize,
4878                                p2i(r->bottom()),
4879                                r->rem_set()->occupied(),
4880                                r->rem_set()->strong_code_roots_list_length(),
4881                                next_bitmap->isMarked(r->bottom()),
4882                                g1h->is_humongous_reclaim_candidate(region_idx),
4883                                obj->is_typeArray()
4884                               );
4885       return false;
4886     }
4887 
4888     guarantee(obj->is_typeArray(),
4889               "Only eagerly reclaiming type arrays is supported, but the object "
4890               PTR_FORMAT " is not.", p2i(r->bottom()));
4891 
4892     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",
4893                              region_idx,
4894                              (size_t)obj->size() * HeapWordSize,
4895                              p2i(r->bottom()),
4896                              r->rem_set()->occupied(),
4897                              r->rem_set()->strong_code_roots_list_length(),
4898                              next_bitmap->isMarked(r->bottom()),
4899                              g1h->is_humongous_reclaim_candidate(region_idx),
4900                              obj->is_typeArray()
4901                             );
4902 
4903     // Need to clear mark bit of the humongous object if already set.
4904     if (next_bitmap->isMarked(r->bottom())) {
4905       next_bitmap->clear(r->bottom());
4906     }
4907     do {
4908       HeapRegion* next = g1h->next_region_in_humongous(r);
4909       _freed_bytes += r->used();
4910       r->set_containing_set(NULL);
4911       _humongous_regions_removed++;
4912       g1h->free_humongous_region(r, _free_region_list, false);
4913       r = next;
4914     } while (r != NULL);
4915 
4916     return false;
4917   }
4918 
4919   uint humongous_free_count() {
4920     return _humongous_regions_removed;
4921   }
4922 
4923   size_t bytes_freed() const {
4924     return _freed_bytes;
4925   }
4926 };
4927 
4928 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4929   assert_at_safepoint(true);
4930 
4931   if (!G1EagerReclaimHumongousObjects ||
4932       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4933     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4934     return;
4935   }
4936 
4937   double start_time = os::elapsedTime();
4938 
4939   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4940 
4941   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4942   heap_region_iterate(&cl);
4943 
4944   remove_from_old_sets(0, cl.humongous_free_count());
4945 
4946   G1HRPrinter* hrp = hr_printer();
4947   if (hrp->is_active()) {
4948     FreeRegionListIterator iter(&local_cleanup_list);
4949     while (iter.more_available()) {
4950       HeapRegion* hr = iter.get_next();
4951       hrp->cleanup(hr);
4952     }
4953   }
4954 
4955   prepend_to_freelist(&local_cleanup_list);
4956   decrement_summary_bytes(cl.bytes_freed());
4957 
4958   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4959                                                                     cl.humongous_free_count());
4960 }
4961 
4962 // This routine is similar to the above but does not record
4963 // any policy statistics or update free lists; we are abandoning
4964 // the current incremental collection set in preparation of a
4965 // full collection. After the full GC we will start to build up
4966 // the incremental collection set again.
4967 // This is only called when we're doing a full collection
4968 // and is immediately followed by the tearing down of the young list.
4969 
4970 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
4971   HeapRegion* cur = cs_head;
4972 
4973   while (cur != NULL) {
4974     HeapRegion* next = cur->next_in_collection_set();
4975     assert(cur->in_collection_set(), "bad CS");
4976     cur->set_next_in_collection_set(NULL);
4977     clear_in_cset(cur);
4978     cur->set_young_index_in_cset(-1);
4979     cur = next;
4980   }
4981 }
4982 
4983 void G1CollectedHeap::set_free_regions_coming() {
4984   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4985 
4986   assert(!free_regions_coming(), "pre-condition");
4987   _free_regions_coming = true;
4988 }
4989 
4990 void G1CollectedHeap::reset_free_regions_coming() {
4991   assert(free_regions_coming(), "pre-condition");
4992 
4993   {
4994     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4995     _free_regions_coming = false;
4996     SecondaryFreeList_lock->notify_all();
4997   }
4998 
4999   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5000 }
5001 
5002 void G1CollectedHeap::wait_while_free_regions_coming() {
5003   // Most of the time we won't have to wait, so let's do a quick test
5004   // first before we take the lock.
5005   if (!free_regions_coming()) {
5006     return;
5007   }
5008 
5009   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5010 
5011   {
5012     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5013     while (free_regions_coming()) {
5014       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5015     }
5016   }
5017 
5018   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5019 }
5020 
5021 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5022   return _allocator->is_retained_old_region(hr);
5023 }
5024 
5025 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5026   _eden.add(hr);
5027   _g1_policy->set_region_eden(hr);
5028 }
5029 
5030 #ifdef ASSERT
5031 
5032 class NoYoungRegionsClosure: public HeapRegionClosure {
5033 private:
5034   bool _success;
5035 public:
5036   NoYoungRegionsClosure() : _success(true) { }
5037   bool doHeapRegion(HeapRegion* r) {
5038     if (r->is_young()) {
5039       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5040                             p2i(r->bottom()), p2i(r->end()));
5041       _success = false;
5042     }
5043     return false;
5044   }
5045   bool success() { return _success; }
5046 };
5047 
5048 bool G1CollectedHeap::check_young_list_empty() {
5049   bool ret = (young_regions_count() == 0);
5050 
5051   NoYoungRegionsClosure closure;
5052   heap_region_iterate(&closure);
5053   ret = ret && closure.success();
5054 
5055   return ret;
5056 }
5057 
5058 #endif // ASSERT
5059 
5060 class TearDownRegionSetsClosure : public HeapRegionClosure {
5061 private:
5062   HeapRegionSet *_old_set;
5063 
5064 public:
5065   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5066 
5067   bool doHeapRegion(HeapRegion* r) {
5068     if (r->is_old()) {
5069       _old_set->remove(r);
5070     } else if(r->is_young()) {
5071       r->uninstall_surv_rate_group();
5072     } else {
5073       // We ignore free regions, we'll empty the free list afterwards.
5074       // We ignore humongous regions, we're not tearing down the
5075       // humongous regions set.
5076       assert(r->is_free() || r->is_humongous(),
5077              "it cannot be another type");
5078     }
5079     return false;
5080   }
5081 
5082   ~TearDownRegionSetsClosure() {
5083     assert(_old_set->is_empty(), "post-condition");
5084   }
5085 };
5086 
5087 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5088   assert_at_safepoint(true /* should_be_vm_thread */);
5089 
5090   if (!free_list_only) {
5091     TearDownRegionSetsClosure cl(&_old_set);
5092     heap_region_iterate(&cl);
5093 
5094     // Note that emptying the _young_list is postponed and instead done as
5095     // the first step when rebuilding the regions sets again. The reason for
5096     // this is that during a full GC string deduplication needs to know if
5097     // a collected region was young or old when the full GC was initiated.
5098   }
5099   _hrm.remove_all_free_regions();
5100 }
5101 
5102 void G1CollectedHeap::increase_used(size_t bytes) {
5103   _summary_bytes_used += bytes;
5104 }
5105 
5106 void G1CollectedHeap::decrease_used(size_t bytes) {
5107   assert(_summary_bytes_used >= bytes,
5108          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5109          _summary_bytes_used, bytes);
5110   _summary_bytes_used -= bytes;
5111 }
5112 
5113 void G1CollectedHeap::set_used(size_t bytes) {
5114   _summary_bytes_used = bytes;
5115 }
5116 
5117 class RebuildRegionSetsClosure : public HeapRegionClosure {
5118 private:
5119   bool            _free_list_only;
5120   HeapRegionSet*   _old_set;
5121   HeapRegionManager*   _hrm;
5122   size_t          _total_used;
5123 
5124 public:
5125   RebuildRegionSetsClosure(bool free_list_only,
5126                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5127     _free_list_only(free_list_only),
5128     _old_set(old_set), _hrm(hrm), _total_used(0) {
5129     assert(_hrm->num_free_regions() == 0, "pre-condition");
5130     if (!free_list_only) {
5131       assert(_old_set->is_empty(), "pre-condition");
5132     }
5133   }
5134 
5135   bool doHeapRegion(HeapRegion* r) {
5136     if (r->is_empty()) {
5137       // Add free regions to the free list
5138       r->set_free();
5139       r->set_allocation_context(AllocationContext::system());
5140       _hrm->insert_into_free_list(r);
5141     } else if (!_free_list_only) {
5142 
5143       if (r->is_humongous()) {
5144         // We ignore humongous regions. We left the humongous set unchanged.
5145       } else {
5146         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5147         // We now consider all regions old, so register as such. Leave
5148         // archive regions set that way, however, while still adding
5149         // them to the old set.
5150         if (!r->is_archive()) {
5151           r->set_old();
5152         }
5153         _old_set->add(r);
5154       }
5155       _total_used += r->used();
5156     }
5157 
5158     return false;
5159   }
5160 
5161   size_t total_used() {
5162     return _total_used;
5163   }
5164 };
5165 
5166 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5167   assert_at_safepoint(true /* should_be_vm_thread */);
5168 
5169   if (!free_list_only) {
5170     _eden.clear();
5171     _survivor.clear();
5172   }
5173 
5174   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5175   heap_region_iterate(&cl);
5176 
5177   if (!free_list_only) {
5178     set_used(cl.total_used());
5179     if (_archive_allocator != NULL) {
5180       _archive_allocator->clear_used();
5181     }
5182   }
5183   assert(used_unlocked() == recalculate_used(),
5184          "inconsistent used_unlocked(), "
5185          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5186          used_unlocked(), recalculate_used());
5187 }
5188 
5189 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5190   _refine_cte_cl->set_concurrent(concurrent);
5191 }
5192 
5193 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5194   HeapRegion* hr = heap_region_containing(p);
5195   return hr->is_in(p);
5196 }
5197 
5198 // Methods for the mutator alloc region
5199 
5200 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5201                                                       bool force) {
5202   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5203   assert(!force || g1_policy()->can_expand_young_list(),
5204          "if force is true we should be able to expand the young list");
5205   bool should_allocate = g1_policy()->should_allocate_mutator_region();
5206   if (force || should_allocate) {
5207     HeapRegion* new_alloc_region = new_region(word_size,
5208                                               false /* is_old */,
5209                                               false /* do_expand */);
5210     if (new_alloc_region != NULL) {
5211       set_region_short_lived_locked(new_alloc_region);
5212       _hr_printer.alloc(new_alloc_region, !should_allocate);
5213       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5214       return new_alloc_region;
5215     }
5216   }
5217   return NULL;
5218 }
5219 
5220 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5221                                                   size_t allocated_bytes) {
5222   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5223   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5224 
5225   collection_set()->add_eden_region(alloc_region);
5226   increase_used(allocated_bytes);
5227   _hr_printer.retire(alloc_region);
5228   // We update the eden sizes here, when the region is retired,
5229   // instead of when it's allocated, since this is the point that its
5230   // used space has been recored in _summary_bytes_used.
5231   g1mm()->update_eden_size();
5232 }
5233 
5234 // Methods for the GC alloc regions
5235 
5236 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5237   if (dest.is_old()) {
5238     return true;
5239   } else {
5240     return survivor_regions_count() < g1_policy()->max_survivor_regions();
5241   }
5242 }
5243 
5244 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5245   assert(FreeList_lock->owned_by_self(), "pre-condition");
5246 
5247   if (!has_more_regions(dest)) {
5248     return NULL;
5249   }
5250 
5251   const bool is_survivor = dest.is_young();
5252 
5253   HeapRegion* new_alloc_region = new_region(word_size,
5254                                             !is_survivor,
5255                                             true /* do_expand */);
5256   if (new_alloc_region != NULL) {
5257     // We really only need to do this for old regions given that we
5258     // should never scan survivors. But it doesn't hurt to do it
5259     // for survivors too.
5260     new_alloc_region->record_timestamp();
5261     if (is_survivor) {
5262       new_alloc_region->set_survivor();
5263       _survivor.add(new_alloc_region);
5264       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5265     } else {
5266       new_alloc_region->set_old();
5267       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5268     }
5269     _hr_printer.alloc(new_alloc_region);
5270     bool during_im = collector_state()->during_initial_mark_pause();
5271     new_alloc_region->note_start_of_copying(during_im);
5272     return new_alloc_region;
5273   }
5274   return NULL;
5275 }
5276 
5277 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5278                                              size_t allocated_bytes,
5279                                              InCSetState dest) {
5280   bool during_im = collector_state()->during_initial_mark_pause();
5281   alloc_region->note_end_of_copying(during_im);
5282   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5283   if (dest.is_old()) {
5284     _old_set.add(alloc_region);
5285   }
5286   _hr_printer.retire(alloc_region);
5287 }
5288 
5289 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5290   bool expanded = false;
5291   uint index = _hrm.find_highest_free(&expanded);
5292 
5293   if (index != G1_NO_HRM_INDEX) {
5294     if (expanded) {
5295       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5296                                 HeapRegion::GrainWords * HeapWordSize);
5297     }
5298     _hrm.allocate_free_regions_starting_at(index, 1);
5299     return region_at(index);
5300   }
5301   return NULL;
5302 }
5303 
5304 // Optimized nmethod scanning
5305 
5306 class RegisterNMethodOopClosure: public OopClosure {
5307   G1CollectedHeap* _g1h;
5308   nmethod* _nm;
5309 
5310   template <class T> void do_oop_work(T* p) {
5311     T heap_oop = oopDesc::load_heap_oop(p);
5312     if (!oopDesc::is_null(heap_oop)) {
5313       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5314       HeapRegion* hr = _g1h->heap_region_containing(obj);
5315       assert(!hr->is_continues_humongous(),
5316              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5317              " starting at " HR_FORMAT,
5318              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5319 
5320       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5321       hr->add_strong_code_root_locked(_nm);
5322     }
5323   }
5324 
5325 public:
5326   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5327     _g1h(g1h), _nm(nm) {}
5328 
5329   void do_oop(oop* p)       { do_oop_work(p); }
5330   void do_oop(narrowOop* p) { do_oop_work(p); }
5331 };
5332 
5333 class UnregisterNMethodOopClosure: public OopClosure {
5334   G1CollectedHeap* _g1h;
5335   nmethod* _nm;
5336 
5337   template <class T> void do_oop_work(T* p) {
5338     T heap_oop = oopDesc::load_heap_oop(p);
5339     if (!oopDesc::is_null(heap_oop)) {
5340       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5341       HeapRegion* hr = _g1h->heap_region_containing(obj);
5342       assert(!hr->is_continues_humongous(),
5343              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5344              " starting at " HR_FORMAT,
5345              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5346 
5347       hr->remove_strong_code_root(_nm);
5348     }
5349   }
5350 
5351 public:
5352   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5353     _g1h(g1h), _nm(nm) {}
5354 
5355   void do_oop(oop* p)       { do_oop_work(p); }
5356   void do_oop(narrowOop* p) { do_oop_work(p); }
5357 };
5358 
5359 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5360   CollectedHeap::register_nmethod(nm);
5361 
5362   guarantee(nm != NULL, "sanity");
5363   RegisterNMethodOopClosure reg_cl(this, nm);
5364   nm->oops_do(&reg_cl);
5365 }
5366 
5367 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5368   CollectedHeap::unregister_nmethod(nm);
5369 
5370   guarantee(nm != NULL, "sanity");
5371   UnregisterNMethodOopClosure reg_cl(this, nm);
5372   nm->oops_do(&reg_cl, true);
5373 }
5374 
5375 void G1CollectedHeap::purge_code_root_memory() {
5376   double purge_start = os::elapsedTime();
5377   G1CodeRootSet::purge();
5378   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5379   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5380 }
5381 
5382 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5383   G1CollectedHeap* _g1h;
5384 
5385 public:
5386   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5387     _g1h(g1h) {}
5388 
5389   void do_code_blob(CodeBlob* cb) {
5390     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5391     if (nm == NULL) {
5392       return;
5393     }
5394 
5395     if (ScavengeRootsInCode) {
5396       _g1h->register_nmethod(nm);
5397     }
5398   }
5399 };
5400 
5401 void G1CollectedHeap::rebuild_strong_code_roots() {
5402   RebuildStrongCodeRootClosure blob_cl(this);
5403   CodeCache::blobs_do(&blob_cl);
5404 }