1 /*
   2  * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoaderDataGraph.hpp"
  27 #include "classfile/metadataOnStackMark.hpp"
  28 #include "classfile/stringTable.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "gc/g1/g1Allocator.inline.hpp"
  32 #include "gc/g1/g1BarrierSet.hpp"
  33 #include "gc/g1/g1CollectedHeap.inline.hpp"
  34 #include "gc/g1/g1CollectionSet.hpp"
  35 #include "gc/g1/g1CollectorPolicy.hpp"
  36 #include "gc/g1/g1CollectorState.hpp"
  37 #include "gc/g1/g1ConcurrentRefine.hpp"
  38 #include "gc/g1/g1ConcurrentRefineThread.hpp"
  39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
  40 #include "gc/g1/g1EvacStats.inline.hpp"
  41 #include "gc/g1/g1FullCollector.hpp"
  42 #include "gc/g1/g1GCPhaseTimes.hpp"
  43 #include "gc/g1/g1HeapSizingPolicy.hpp"
  44 #include "gc/g1/g1HeapTransition.hpp"
  45 #include "gc/g1/g1HeapVerifier.hpp"
  46 #include "gc/g1/g1HotCardCache.hpp"
  47 #include "gc/g1/g1MemoryPool.hpp"
  48 #include "gc/g1/g1OopClosures.inline.hpp"
  49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  50 #include "gc/g1/g1Policy.hpp"
  51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  52 #include "gc/g1/g1RemSet.hpp"
  53 #include "gc/g1/g1RootClosures.hpp"
  54 #include "gc/g1/g1RootProcessor.hpp"
  55 #include "gc/g1/g1SATBMarkQueueSet.hpp"
  56 #include "gc/g1/g1StringDedup.hpp"
  57 #include "gc/g1/g1ThreadLocalData.hpp"
  58 #include "gc/g1/g1YCTypes.hpp"
  59 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  60 #include "gc/g1/heapRegion.inline.hpp"
  61 #include "gc/g1/heapRegionRemSet.hpp"
  62 #include "gc/g1/heapRegionSet.inline.hpp"
  63 #include "gc/g1/vm_operations_g1.hpp"
  64 #include "gc/shared/adaptiveSizePolicy.hpp"
  65 #include "gc/shared/gcHeapSummary.hpp"
  66 #include "gc/shared/gcId.hpp"
  67 #include "gc/shared/gcLocker.hpp"
  68 #include "gc/shared/gcTimer.hpp"
  69 #include "gc/shared/gcTrace.hpp"
  70 #include "gc/shared/gcTraceTime.inline.hpp"
  71 #include "gc/shared/generationSpec.hpp"
  72 #include "gc/shared/isGCActiveMark.hpp"
  73 #include "gc/shared/oopStorageParState.hpp"
  74 #include "gc/shared/parallelCleaning.hpp"
  75 #include "gc/shared/preservedMarks.inline.hpp"
  76 #include "gc/shared/suspendibleThreadSet.hpp"
  77 #include "gc/shared/referenceProcessor.inline.hpp"
  78 #include "gc/shared/taskqueue.inline.hpp"
  79 #include "gc/shared/weakProcessor.inline.hpp"
  80 #include "logging/log.hpp"
  81 #include "memory/allocation.hpp"
  82 #include "memory/iterator.hpp"
  83 #include "memory/resourceArea.hpp"
  84 #include "oops/access.inline.hpp"
  85 #include "oops/compressedOops.inline.hpp"
  86 #include "oops/oop.inline.hpp"
  87 #include "runtime/atomic.hpp"
  88 #include "runtime/flags/flagSetting.hpp"
  89 #include "runtime/handles.inline.hpp"
  90 #include "runtime/init.hpp"
  91 #include "runtime/orderAccess.hpp"
  92 #include "runtime/threadSMR.hpp"
  93 #include "runtime/vmThread.hpp"
  94 #include "utilities/align.hpp"
  95 #include "utilities/globalDefinitions.hpp"
  96 #include "utilities/stack.inline.hpp"
  97 
  98 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  99 
 100 // INVARIANTS/NOTES
 101 //
 102 // All allocation activity covered by the G1CollectedHeap interface is
 103 // serialized by acquiring the HeapLock.  This happens in mem_allocate
 104 // and allocate_new_tlab, which are the "entry" points to the
 105 // allocation code from the rest of the JVM.  (Note that this does not
 106 // apply to TLAB allocation, which is not part of this interface: it
 107 // is done by clients of this interface.)
 108 
 109 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 110  private:
 111   size_t _num_dirtied;
 112   G1CollectedHeap* _g1h;
 113   G1CardTable* _g1_ct;
 114 
 115   HeapRegion* region_for_card(jbyte* card_ptr) const {
 116     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
 117   }
 118 
 119   bool will_become_free(HeapRegion* hr) const {
 120     // A region will be freed by free_collection_set if the region is in the
 121     // collection set and has not had an evacuation failure.
 122     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 123   }
 124 
 125  public:
 126   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 127     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
 128 
 129   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 130     HeapRegion* hr = region_for_card(card_ptr);
 131 
 132     // Should only dirty cards in regions that won't be freed.
 133     if (!will_become_free(hr)) {
 134       *card_ptr = G1CardTable::dirty_card_val();
 135       _num_dirtied++;
 136     }
 137 
 138     return true;
 139   }
 140 
 141   size_t num_dirtied()   const { return _num_dirtied; }
 142 };
 143 
 144 
 145 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 146   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 147 }
 148 
 149 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 150   // The from card cache is not the memory that is actually committed. So we cannot
 151   // take advantage of the zero_filled parameter.
 152   reset_from_card_cache(start_idx, num_regions);
 153 }
 154 
 155 
 156 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 157                                              MemRegion mr) {
 158   return new HeapRegion(hrs_index, bot(), mr);
 159 }
 160 
 161 // Private methods.
 162 
 163 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 164   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 165          "the only time we use this to allocate a humongous region is "
 166          "when we are allocating a single humongous region");
 167 
 168   HeapRegion* res = _hrm.allocate_free_region(is_old);
 169 
 170   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 171     // Currently, only attempts to allocate GC alloc regions set
 172     // do_expand to true. So, we should only reach here during a
 173     // safepoint. If this assumption changes we might have to
 174     // reconsider the use of _expand_heap_after_alloc_failure.
 175     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 176 
 177     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 178                               word_size * HeapWordSize);
 179 
 180     if (expand(word_size * HeapWordSize)) {
 181       // Given that expand() succeeded in expanding the heap, and we
 182       // always expand the heap by an amount aligned to the heap
 183       // region size, the free list should in theory not be empty.
 184       // In either case allocate_free_region() will check for NULL.
 185       res = _hrm.allocate_free_region(is_old);
 186     } else {
 187       _expand_heap_after_alloc_failure = false;
 188     }
 189   }
 190   return res;
 191 }
 192 
 193 HeapWord*
 194 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 195                                                            uint num_regions,
 196                                                            size_t word_size) {
 197   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 198   assert(is_humongous(word_size), "word_size should be humongous");
 199   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 200 
 201   // Index of last region in the series.
 202   uint last = first + num_regions - 1;
 203 
 204   // We need to initialize the region(s) we just discovered. This is
 205   // a bit tricky given that it can happen concurrently with
 206   // refinement threads refining cards on these regions and
 207   // potentially wanting to refine the BOT as they are scanning
 208   // those cards (this can happen shortly after a cleanup; see CR
 209   // 6991377). So we have to set up the region(s) carefully and in
 210   // a specific order.
 211 
 212   // The word size sum of all the regions we will allocate.
 213   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 214   assert(word_size <= word_size_sum, "sanity");
 215 
 216   // This will be the "starts humongous" region.
 217   HeapRegion* first_hr = region_at(first);
 218   // The header of the new object will be placed at the bottom of
 219   // the first region.
 220   HeapWord* new_obj = first_hr->bottom();
 221   // This will be the new top of the new object.
 222   HeapWord* obj_top = new_obj + word_size;
 223 
 224   // First, we need to zero the header of the space that we will be
 225   // allocating. When we update top further down, some refinement
 226   // threads might try to scan the region. By zeroing the header we
 227   // ensure that any thread that will try to scan the region will
 228   // come across the zero klass word and bail out.
 229   //
 230   // NOTE: It would not have been correct to have used
 231   // CollectedHeap::fill_with_object() and make the space look like
 232   // an int array. The thread that is doing the allocation will
 233   // later update the object header to a potentially different array
 234   // type and, for a very short period of time, the klass and length
 235   // fields will be inconsistent. This could cause a refinement
 236   // thread to calculate the object size incorrectly.
 237   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 238 
 239   // Next, pad out the unused tail of the last region with filler
 240   // objects, for improved usage accounting.
 241   // How many words we use for filler objects.
 242   size_t word_fill_size = word_size_sum - word_size;
 243 
 244   // How many words memory we "waste" which cannot hold a filler object.
 245   size_t words_not_fillable = 0;
 246 
 247   if (word_fill_size >= min_fill_size()) {
 248     fill_with_objects(obj_top, word_fill_size);
 249   } else if (word_fill_size > 0) {
 250     // We have space to fill, but we cannot fit an object there.
 251     words_not_fillable = word_fill_size;
 252     word_fill_size = 0;
 253   }
 254 
 255   // We will set up the first region as "starts humongous". This
 256   // will also update the BOT covering all the regions to reflect
 257   // that there is a single object that starts at the bottom of the
 258   // first region.
 259   first_hr->set_starts_humongous(obj_top, word_fill_size);
 260   _g1_policy->remset_tracker()->update_at_allocate(first_hr);
 261   // Then, if there are any, we will set up the "continues
 262   // humongous" regions.
 263   HeapRegion* hr = NULL;
 264   for (uint i = first + 1; i <= last; ++i) {
 265     hr = region_at(i);
 266     hr->set_continues_humongous(first_hr);
 267     _g1_policy->remset_tracker()->update_at_allocate(hr);
 268   }
 269 
 270   // Up to this point no concurrent thread would have been able to
 271   // do any scanning on any region in this series. All the top
 272   // fields still point to bottom, so the intersection between
 273   // [bottom,top] and [card_start,card_end] will be empty. Before we
 274   // update the top fields, we'll do a storestore to make sure that
 275   // no thread sees the update to top before the zeroing of the
 276   // object header and the BOT initialization.
 277   OrderAccess::storestore();
 278 
 279   // Now, we will update the top fields of the "continues humongous"
 280   // regions except the last one.
 281   for (uint i = first; i < last; ++i) {
 282     hr = region_at(i);
 283     hr->set_top(hr->end());
 284   }
 285 
 286   hr = region_at(last);
 287   // If we cannot fit a filler object, we must set top to the end
 288   // of the humongous object, otherwise we cannot iterate the heap
 289   // and the BOT will not be complete.
 290   hr->set_top(hr->end() - words_not_fillable);
 291 
 292   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 293          "obj_top should be in last region");
 294 
 295   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 296 
 297   assert(words_not_fillable == 0 ||
 298          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 299          "Miscalculation in humongous allocation");
 300 
 301   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 302 
 303   for (uint i = first; i <= last; ++i) {
 304     hr = region_at(i);
 305     _humongous_set.add(hr);
 306     _hr_printer.alloc(hr);
 307   }
 308 
 309   return new_obj;
 310 }
 311 
 312 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 313   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 314   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 315 }
 316 
 317 // If could fit into free regions w/o expansion, try.
 318 // Otherwise, if can expand, do so.
 319 // Otherwise, if using ex regions might help, try with ex given back.
 320 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 321   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 322 
 323   _verifier->verify_region_sets_optional();
 324 
 325   uint first = G1_NO_HRM_INDEX;
 326   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 327 
 328   if (obj_regions == 1) {
 329     // Only one region to allocate, try to use a fast path by directly allocating
 330     // from the free lists. Do not try to expand here, we will potentially do that
 331     // later.
 332     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 333     if (hr != NULL) {
 334       first = hr->hrm_index();
 335     }
 336   } else {
 337     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 338     // are lucky enough to find some.
 339     first = _hrm.find_contiguous_only_empty(obj_regions);
 340     if (first != G1_NO_HRM_INDEX) {
 341       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 342     }
 343   }
 344 
 345   if (first == G1_NO_HRM_INDEX) {
 346     // Policy: We could not find enough regions for the humongous object in the
 347     // free list. Look through the heap to find a mix of free and uncommitted regions.
 348     // If so, try expansion.
 349     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 350     if (first != G1_NO_HRM_INDEX) {
 351       // We found something. Make sure these regions are committed, i.e. expand
 352       // the heap. Alternatively we could do a defragmentation GC.
 353       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 354                                     word_size * HeapWordSize);
 355 
 356       _hrm.expand_at(first, obj_regions, workers());
 357       g1_policy()->record_new_heap_size(num_regions());
 358 
 359 #ifdef ASSERT
 360       for (uint i = first; i < first + obj_regions; ++i) {
 361         HeapRegion* hr = region_at(i);
 362         assert(hr->is_free(), "sanity");
 363         assert(hr->is_empty(), "sanity");
 364         assert(is_on_master_free_list(hr), "sanity");
 365       }
 366 #endif
 367       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 368     } else {
 369       // Policy: Potentially trigger a defragmentation GC.
 370     }
 371   }
 372 
 373   HeapWord* result = NULL;
 374   if (first != G1_NO_HRM_INDEX) {
 375     result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
 376     assert(result != NULL, "it should always return a valid result");
 377 
 378     // A successful humongous object allocation changes the used space
 379     // information of the old generation so we need to recalculate the
 380     // sizes and update the jstat counters here.
 381     g1mm()->update_sizes();
 382   }
 383 
 384   _verifier->verify_region_sets_optional();
 385 
 386   return result;
 387 }
 388 
 389 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
 390                                              size_t requested_size,
 391                                              size_t* actual_size) {
 392   assert_heap_not_locked_and_not_at_safepoint();
 393   assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
 394 
 395   return attempt_allocation(min_size, requested_size, actual_size);
 396 }
 397 
 398 HeapWord*
 399 G1CollectedHeap::mem_allocate(size_t word_size,
 400                               bool*  gc_overhead_limit_was_exceeded) {
 401   assert_heap_not_locked_and_not_at_safepoint();
 402 
 403   if (is_humongous(word_size)) {
 404     return attempt_allocation_humongous(word_size);
 405   }
 406   size_t dummy = 0;
 407   return attempt_allocation(word_size, word_size, &dummy);
 408 }
 409 
 410 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 411   ResourceMark rm; // For retrieving the thread names in log messages.
 412 
 413   // Make sure you read the note in attempt_allocation_humongous().
 414 
 415   assert_heap_not_locked_and_not_at_safepoint();
 416   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 417          "be called for humongous allocation requests");
 418 
 419   // We should only get here after the first-level allocation attempt
 420   // (attempt_allocation()) failed to allocate.
 421 
 422   // We will loop until a) we manage to successfully perform the
 423   // allocation or b) we successfully schedule a collection which
 424   // fails to perform the allocation. b) is the only case when we'll
 425   // return NULL.
 426   HeapWord* result = NULL;
 427   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 428     bool should_try_gc;
 429     uint gc_count_before;
 430 
 431     {
 432       MutexLockerEx x(Heap_lock);
 433       result = _allocator->attempt_allocation_locked(word_size);
 434       if (result != NULL) {
 435         return result;
 436       }
 437 
 438       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 439       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 440       // waiting because the GCLocker is active to not wait too long.
 441       if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
 442         // No need for an ergo message here, can_expand_young_list() does this when
 443         // it returns true.
 444         result = _allocator->attempt_allocation_force(word_size);
 445         if (result != NULL) {
 446           return result;
 447         }
 448       }
 449       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 450       // the GCLocker initiated GC has been performed and then retry. This includes
 451       // the case when the GC Locker is not active but has not been performed.
 452       should_try_gc = !GCLocker::needs_gc();
 453       // Read the GC count while still holding the Heap_lock.
 454       gc_count_before = total_collections();
 455     }
 456 
 457     if (should_try_gc) {
 458       bool succeeded;
 459       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 460                                    GCCause::_g1_inc_collection_pause);
 461       if (result != NULL) {
 462         assert(succeeded, "only way to get back a non-NULL result");
 463         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 464                              Thread::current()->name(), p2i(result));
 465         return result;
 466       }
 467 
 468       if (succeeded) {
 469         // We successfully scheduled a collection which failed to allocate. No
 470         // point in trying to allocate further. We'll just return NULL.
 471         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 472                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 473         return NULL;
 474       }
 475       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 476                            Thread::current()->name(), word_size);
 477     } else {
 478       // Failed to schedule a collection.
 479       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 480         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 481                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 482         return NULL;
 483       }
 484       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 485       // The GCLocker is either active or the GCLocker initiated
 486       // GC has not yet been performed. Stall until it is and
 487       // then retry the allocation.
 488       GCLocker::stall_until_clear();
 489       gclocker_retry_count += 1;
 490     }
 491 
 492     // We can reach here if we were unsuccessful in scheduling a
 493     // collection (because another thread beat us to it) or if we were
 494     // stalled due to the GC locker. In either can we should retry the
 495     // allocation attempt in case another thread successfully
 496     // performed a collection and reclaimed enough space. We do the
 497     // first attempt (without holding the Heap_lock) here and the
 498     // follow-on attempt will be at the start of the next loop
 499     // iteration (after taking the Heap_lock).
 500     size_t dummy = 0;
 501     result = _allocator->attempt_allocation(word_size, word_size, &dummy);
 502     if (result != NULL) {
 503       return result;
 504     }
 505 
 506     // Give a warning if we seem to be looping forever.
 507     if ((QueuedAllocationWarningCount > 0) &&
 508         (try_count % QueuedAllocationWarningCount == 0)) {
 509       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 510                              Thread::current()->name(), try_count, word_size);
 511     }
 512   }
 513 
 514   ShouldNotReachHere();
 515   return NULL;
 516 }
 517 
 518 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 519   assert_at_safepoint_on_vm_thread();
 520   if (_archive_allocator == NULL) {
 521     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 522   }
 523 }
 524 
 525 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 526   // Allocations in archive regions cannot be of a size that would be considered
 527   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 528   // may be different at archive-restore time.
 529   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 530 }
 531 
 532 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 533   assert_at_safepoint_on_vm_thread();
 534   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 535   if (is_archive_alloc_too_large(word_size)) {
 536     return NULL;
 537   }
 538   return _archive_allocator->archive_mem_allocate(word_size);
 539 }
 540 
 541 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 542                                               size_t end_alignment_in_bytes) {
 543   assert_at_safepoint_on_vm_thread();
 544   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 545 
 546   // Call complete_archive to do the real work, filling in the MemRegion
 547   // array with the archive regions.
 548   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 549   delete _archive_allocator;
 550   _archive_allocator = NULL;
 551 }
 552 
 553 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 554   assert(ranges != NULL, "MemRegion array NULL");
 555   assert(count != 0, "No MemRegions provided");
 556   MemRegion reserved = _hrm.reserved();
 557   for (size_t i = 0; i < count; i++) {
 558     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 559       return false;
 560     }
 561   }
 562   return true;
 563 }
 564 
 565 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 566                                             size_t count,
 567                                             bool open) {
 568   assert(!is_init_completed(), "Expect to be called at JVM init time");
 569   assert(ranges != NULL, "MemRegion array NULL");
 570   assert(count != 0, "No MemRegions provided");
 571   MutexLockerEx x(Heap_lock);
 572 
 573   MemRegion reserved = _hrm.reserved();
 574   HeapWord* prev_last_addr = NULL;
 575   HeapRegion* prev_last_region = NULL;
 576 
 577   // Temporarily disable pretouching of heap pages. This interface is used
 578   // when mmap'ing archived heap data in, so pre-touching is wasted.
 579   FlagSetting fs(AlwaysPreTouch, false);
 580 
 581   // Enable archive object checking used by G1MarkSweep. We have to let it know
 582   // about each archive range, so that objects in those ranges aren't marked.
 583   G1ArchiveAllocator::enable_archive_object_check();
 584 
 585   // For each specified MemRegion range, allocate the corresponding G1
 586   // regions and mark them as archive regions. We expect the ranges
 587   // in ascending starting address order, without overlap.
 588   for (size_t i = 0; i < count; i++) {
 589     MemRegion curr_range = ranges[i];
 590     HeapWord* start_address = curr_range.start();
 591     size_t word_size = curr_range.word_size();
 592     HeapWord* last_address = curr_range.last();
 593     size_t commits = 0;
 594 
 595     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 596               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 597               p2i(start_address), p2i(last_address));
 598     guarantee(start_address > prev_last_addr,
 599               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 600               p2i(start_address), p2i(prev_last_addr));
 601     prev_last_addr = last_address;
 602 
 603     // Check for ranges that start in the same G1 region in which the previous
 604     // range ended, and adjust the start address so we don't try to allocate
 605     // the same region again. If the current range is entirely within that
 606     // region, skip it, just adjusting the recorded top.
 607     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 608     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 609       start_address = start_region->end();
 610       if (start_address > last_address) {
 611         increase_used(word_size * HeapWordSize);
 612         start_region->set_top(last_address + 1);
 613         continue;
 614       }
 615       start_region->set_top(start_address);
 616       curr_range = MemRegion(start_address, last_address + 1);
 617       start_region = _hrm.addr_to_region(start_address);
 618     }
 619 
 620     // Perform the actual region allocation, exiting if it fails.
 621     // Then note how much new space we have allocated.
 622     if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
 623       return false;
 624     }
 625     increase_used(word_size * HeapWordSize);
 626     if (commits != 0) {
 627       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 628                                 HeapRegion::GrainWords * HeapWordSize * commits);
 629 
 630     }
 631 
 632     // Mark each G1 region touched by the range as archive, add it to
 633     // the old set, and set top.
 634     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 635     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 636     prev_last_region = last_region;
 637 
 638     while (curr_region != NULL) {
 639       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 640              "Region already in use (index %u)", curr_region->hrm_index());
 641       if (open) {
 642         curr_region->set_open_archive();
 643       } else {
 644         curr_region->set_closed_archive();
 645       }
 646       _hr_printer.alloc(curr_region);
 647       _archive_set.add(curr_region);
 648       HeapWord* top;
 649       HeapRegion* next_region;
 650       if (curr_region != last_region) {
 651         top = curr_region->end();
 652         next_region = _hrm.next_region_in_heap(curr_region);
 653       } else {
 654         top = last_address + 1;
 655         next_region = NULL;
 656       }
 657       curr_region->set_top(top);
 658       curr_region->set_first_dead(top);
 659       curr_region->set_end_of_live(top);
 660       curr_region = next_region;
 661     }
 662 
 663     // Notify mark-sweep of the archive
 664     G1ArchiveAllocator::set_range_archive(curr_range, open);
 665   }
 666   return true;
 667 }
 668 
 669 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 670   assert(!is_init_completed(), "Expect to be called at JVM init time");
 671   assert(ranges != NULL, "MemRegion array NULL");
 672   assert(count != 0, "No MemRegions provided");
 673   MemRegion reserved = _hrm.reserved();
 674   HeapWord *prev_last_addr = NULL;
 675   HeapRegion* prev_last_region = NULL;
 676 
 677   // For each MemRegion, create filler objects, if needed, in the G1 regions
 678   // that contain the address range. The address range actually within the
 679   // MemRegion will not be modified. That is assumed to have been initialized
 680   // elsewhere, probably via an mmap of archived heap data.
 681   MutexLockerEx x(Heap_lock);
 682   for (size_t i = 0; i < count; i++) {
 683     HeapWord* start_address = ranges[i].start();
 684     HeapWord* last_address = ranges[i].last();
 685 
 686     assert(reserved.contains(start_address) && reserved.contains(last_address),
 687            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 688            p2i(start_address), p2i(last_address));
 689     assert(start_address > prev_last_addr,
 690            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 691            p2i(start_address), p2i(prev_last_addr));
 692 
 693     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 694     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 695     HeapWord* bottom_address = start_region->bottom();
 696 
 697     // Check for a range beginning in the same region in which the
 698     // previous one ended.
 699     if (start_region == prev_last_region) {
 700       bottom_address = prev_last_addr + 1;
 701     }
 702 
 703     // Verify that the regions were all marked as archive regions by
 704     // alloc_archive_regions.
 705     HeapRegion* curr_region = start_region;
 706     while (curr_region != NULL) {
 707       guarantee(curr_region->is_archive(),
 708                 "Expected archive region at index %u", curr_region->hrm_index());
 709       if (curr_region != last_region) {
 710         curr_region = _hrm.next_region_in_heap(curr_region);
 711       } else {
 712         curr_region = NULL;
 713       }
 714     }
 715 
 716     prev_last_addr = last_address;
 717     prev_last_region = last_region;
 718 
 719     // Fill the memory below the allocated range with dummy object(s),
 720     // if the region bottom does not match the range start, or if the previous
 721     // range ended within the same G1 region, and there is a gap.
 722     if (start_address != bottom_address) {
 723       size_t fill_size = pointer_delta(start_address, bottom_address);
 724       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 725       increase_used(fill_size * HeapWordSize);
 726     }
 727   }
 728 }
 729 
 730 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
 731                                                      size_t desired_word_size,
 732                                                      size_t* actual_word_size) {
 733   assert_heap_not_locked_and_not_at_safepoint();
 734   assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
 735          "be called for humongous allocation requests");
 736 
 737   HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
 738 
 739   if (result == NULL) {
 740     *actual_word_size = desired_word_size;
 741     result = attempt_allocation_slow(desired_word_size);
 742   }
 743 
 744   assert_heap_not_locked();
 745   if (result != NULL) {
 746     assert(*actual_word_size != 0, "Actual size must have been set here");
 747     dirty_young_block(result, *actual_word_size);
 748   } else {
 749     *actual_word_size = 0;
 750   }
 751 
 752   return result;
 753 }
 754 
 755 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 756   assert(!is_init_completed(), "Expect to be called at JVM init time");
 757   assert(ranges != NULL, "MemRegion array NULL");
 758   assert(count != 0, "No MemRegions provided");
 759   MemRegion reserved = _hrm.reserved();
 760   HeapWord* prev_last_addr = NULL;
 761   HeapRegion* prev_last_region = NULL;
 762   size_t size_used = 0;
 763   size_t uncommitted_regions = 0;
 764 
 765   // For each Memregion, free the G1 regions that constitute it, and
 766   // notify mark-sweep that the range is no longer to be considered 'archive.'
 767   MutexLockerEx x(Heap_lock);
 768   for (size_t i = 0; i < count; i++) {
 769     HeapWord* start_address = ranges[i].start();
 770     HeapWord* last_address = ranges[i].last();
 771 
 772     assert(reserved.contains(start_address) && reserved.contains(last_address),
 773            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 774            p2i(start_address), p2i(last_address));
 775     assert(start_address > prev_last_addr,
 776            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 777            p2i(start_address), p2i(prev_last_addr));
 778     size_used += ranges[i].byte_size();
 779     prev_last_addr = last_address;
 780 
 781     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 782     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 783 
 784     // Check for ranges that start in the same G1 region in which the previous
 785     // range ended, and adjust the start address so we don't try to free
 786     // the same region again. If the current range is entirely within that
 787     // region, skip it.
 788     if (start_region == prev_last_region) {
 789       start_address = start_region->end();
 790       if (start_address > last_address) {
 791         continue;
 792       }
 793       start_region = _hrm.addr_to_region(start_address);
 794     }
 795     prev_last_region = last_region;
 796 
 797     // After verifying that each region was marked as an archive region by
 798     // alloc_archive_regions, set it free and empty and uncommit it.
 799     HeapRegion* curr_region = start_region;
 800     while (curr_region != NULL) {
 801       guarantee(curr_region->is_archive(),
 802                 "Expected archive region at index %u", curr_region->hrm_index());
 803       uint curr_index = curr_region->hrm_index();
 804       _archive_set.remove(curr_region);
 805       curr_region->set_free();
 806       curr_region->set_top(curr_region->bottom());
 807       if (curr_region != last_region) {
 808         curr_region = _hrm.next_region_in_heap(curr_region);
 809       } else {
 810         curr_region = NULL;
 811       }
 812       _hrm.shrink_at(curr_index, 1);
 813       uncommitted_regions++;
 814     }
 815 
 816     // Notify mark-sweep that this is no longer an archive range.
 817     G1ArchiveAllocator::set_range_archive(ranges[i], false);
 818   }
 819 
 820   if (uncommitted_regions != 0) {
 821     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 822                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 823   }
 824   decrease_used(size_used);
 825 }
 826 
 827 oop G1CollectedHeap::materialize_archived_object(oop obj) {
 828   assert(obj != NULL, "archived obj is NULL");
 829   assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
 830 
 831   // Loading an archived object makes it strongly reachable. If it is
 832   // loaded during concurrent marking, it must be enqueued to the SATB
 833   // queue, shading the previously white object gray.
 834   G1BarrierSet::enqueue(obj);
 835 
 836   return obj;
 837 }
 838 
 839 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 840   ResourceMark rm; // For retrieving the thread names in log messages.
 841 
 842   // The structure of this method has a lot of similarities to
 843   // attempt_allocation_slow(). The reason these two were not merged
 844   // into a single one is that such a method would require several "if
 845   // allocation is not humongous do this, otherwise do that"
 846   // conditional paths which would obscure its flow. In fact, an early
 847   // version of this code did use a unified method which was harder to
 848   // follow and, as a result, it had subtle bugs that were hard to
 849   // track down. So keeping these two methods separate allows each to
 850   // be more readable. It will be good to keep these two in sync as
 851   // much as possible.
 852 
 853   assert_heap_not_locked_and_not_at_safepoint();
 854   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 855          "should only be called for humongous allocations");
 856 
 857   // Humongous objects can exhaust the heap quickly, so we should check if we
 858   // need to start a marking cycle at each humongous object allocation. We do
 859   // the check before we do the actual allocation. The reason for doing it
 860   // before the allocation is that we avoid having to keep track of the newly
 861   // allocated memory while we do a GC.
 862   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 863                                            word_size)) {
 864     collect(GCCause::_g1_humongous_allocation);
 865   }
 866 
 867   // We will loop until a) we manage to successfully perform the
 868   // allocation or b) we successfully schedule a collection which
 869   // fails to perform the allocation. b) is the only case when we'll
 870   // return NULL.
 871   HeapWord* result = NULL;
 872   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 873     bool should_try_gc;
 874     uint gc_count_before;
 875 
 876 
 877     {
 878       MutexLockerEx x(Heap_lock);
 879 
 880       // Given that humongous objects are not allocated in young
 881       // regions, we'll first try to do the allocation without doing a
 882       // collection hoping that there's enough space in the heap.
 883       result = humongous_obj_allocate(word_size);
 884       if (result != NULL) {
 885         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 886         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 887         return result;
 888       }
 889 
 890       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 891       // the GCLocker initiated GC has been performed and then retry. This includes
 892       // the case when the GC Locker is not active but has not been performed.
 893       should_try_gc = !GCLocker::needs_gc();
 894       // Read the GC count while still holding the Heap_lock.
 895       gc_count_before = total_collections();
 896     }
 897 
 898     if (should_try_gc) {
 899       bool succeeded;
 900       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 901                                    GCCause::_g1_humongous_allocation);
 902       if (result != NULL) {
 903         assert(succeeded, "only way to get back a non-NULL result");
 904         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 905                              Thread::current()->name(), p2i(result));
 906         return result;
 907       }
 908 
 909       if (succeeded) {
 910         // We successfully scheduled a collection which failed to allocate. No
 911         // point in trying to allocate further. We'll just return NULL.
 912         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 913                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 914         return NULL;
 915       }
 916       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 917                            Thread::current()->name(), word_size);
 918     } else {
 919       // Failed to schedule a collection.
 920       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 921         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 922                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 923         return NULL;
 924       }
 925       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 926       // The GCLocker is either active or the GCLocker initiated
 927       // GC has not yet been performed. Stall until it is and
 928       // then retry the allocation.
 929       GCLocker::stall_until_clear();
 930       gclocker_retry_count += 1;
 931     }
 932 
 933 
 934     // We can reach here if we were unsuccessful in scheduling a
 935     // collection (because another thread beat us to it) or if we were
 936     // stalled due to the GC locker. In either can we should retry the
 937     // allocation attempt in case another thread successfully
 938     // performed a collection and reclaimed enough space.
 939     // Humongous object allocation always needs a lock, so we wait for the retry
 940     // in the next iteration of the loop, unlike for the regular iteration case.
 941     // Give a warning if we seem to be looping forever.
 942 
 943     if ((QueuedAllocationWarningCount > 0) &&
 944         (try_count % QueuedAllocationWarningCount == 0)) {
 945       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 946                              Thread::current()->name(), try_count, word_size);
 947     }
 948   }
 949 
 950   ShouldNotReachHere();
 951   return NULL;
 952 }
 953 
 954 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 955                                                            bool expect_null_mutator_alloc_region) {
 956   assert_at_safepoint_on_vm_thread();
 957   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 958          "the current alloc region was unexpectedly found to be non-NULL");
 959 
 960   if (!is_humongous(word_size)) {
 961     return _allocator->attempt_allocation_locked(word_size);
 962   } else {
 963     HeapWord* result = humongous_obj_allocate(word_size);
 964     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
 965       collector_state()->set_initiate_conc_mark_if_possible(true);
 966     }
 967     return result;
 968   }
 969 
 970   ShouldNotReachHere();
 971 }
 972 
 973 class PostCompactionPrinterClosure: public HeapRegionClosure {
 974 private:
 975   G1HRPrinter* _hr_printer;
 976 public:
 977   bool do_heap_region(HeapRegion* hr) {
 978     assert(!hr->is_young(), "not expecting to find young regions");
 979     _hr_printer->post_compaction(hr);
 980     return false;
 981   }
 982 
 983   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 984     : _hr_printer(hr_printer) { }
 985 };
 986 
 987 void G1CollectedHeap::print_hrm_post_compaction() {
 988   if (_hr_printer.is_active()) {
 989     PostCompactionPrinterClosure cl(hr_printer());
 990     heap_region_iterate(&cl);
 991   }
 992 }
 993 
 994 void G1CollectedHeap::abort_concurrent_cycle() {
 995   // If we start the compaction before the CM threads finish
 996   // scanning the root regions we might trip them over as we'll
 997   // be moving objects / updating references. So let's wait until
 998   // they are done. By telling them to abort, they should complete
 999   // early.
1000   _cm->root_regions()->abort();
1001   _cm->root_regions()->wait_until_scan_finished();
1002 
1003   // Disable discovery and empty the discovered lists
1004   // for the CM ref processor.
1005   _ref_processor_cm->disable_discovery();
1006   _ref_processor_cm->abandon_partial_discovery();
1007   _ref_processor_cm->verify_no_references_recorded();
1008 
1009   // Abandon current iterations of concurrent marking and concurrent
1010   // refinement, if any are in progress.
1011   concurrent_mark()->concurrent_cycle_abort();
1012 }
1013 
1014 void G1CollectedHeap::prepare_heap_for_full_collection() {
1015   // Make sure we'll choose a new allocation region afterwards.
1016   _allocator->release_mutator_alloc_region();
1017   _allocator->abandon_gc_alloc_regions();
1018   g1_rem_set()->cleanupHRRS();
1019 
1020   // We may have added regions to the current incremental collection
1021   // set between the last GC or pause and now. We need to clear the
1022   // incremental collection set and then start rebuilding it afresh
1023   // after this full GC.
1024   abandon_collection_set(collection_set());
1025 
1026   tear_down_region_sets(false /* free_list_only */);
1027 }
1028 
1029 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1030   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1031   assert(used() == recalculate_used(), "Should be equal");
1032   _verifier->verify_region_sets_optional();
1033   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1034   _verifier->check_bitmaps("Full GC Start");
1035 }
1036 
1037 void G1CollectedHeap::prepare_heap_for_mutators() {
1038   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1039   ClassLoaderDataGraph::purge();
1040   MetaspaceUtils::verify_metrics();
1041 
1042   // Prepare heap for normal collections.
1043   assert(num_free_regions() == 0, "we should not have added any free regions");
1044   rebuild_region_sets(false /* free_list_only */);
1045   abort_refinement();
1046   resize_heap_if_necessary();
1047 
1048   // Rebuild the strong code root lists for each region
1049   rebuild_strong_code_roots();
1050 
1051   // Purge code root memory
1052   purge_code_root_memory();
1053 
1054   // Start a new incremental collection set for the next pause
1055   start_new_collection_set();
1056 
1057   _allocator->init_mutator_alloc_region();
1058 
1059   // Post collection state updates.
1060   MetaspaceGC::compute_new_size();
1061 }
1062 
1063 void G1CollectedHeap::abort_refinement() {
1064   if (_hot_card_cache->use_cache()) {
1065     _hot_card_cache->reset_hot_cache();
1066   }
1067 
1068   // Discard all remembered set updates.
1069   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1070   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1071 }
1072 
1073 void G1CollectedHeap::verify_after_full_collection() {
1074   _hrm.verify_optional();
1075   _verifier->verify_region_sets_optional();
1076   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1077   // Clear the previous marking bitmap, if needed for bitmap verification.
1078   // Note we cannot do this when we clear the next marking bitmap in
1079   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1080   // objects marked during a full GC against the previous bitmap.
1081   // But we need to clear it before calling check_bitmaps below since
1082   // the full GC has compacted objects and updated TAMS but not updated
1083   // the prev bitmap.
1084   if (G1VerifyBitmaps) {
1085     GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification");
1086     _cm->clear_prev_bitmap(workers());
1087   }
1088   // This call implicitly verifies that the next bitmap is clear after Full GC.
1089   _verifier->check_bitmaps("Full GC End");
1090 
1091   // At this point there should be no regions in the
1092   // entire heap tagged as young.
1093   assert(check_young_list_empty(), "young list should be empty at this point");
1094 
1095   // Note: since we've just done a full GC, concurrent
1096   // marking is no longer active. Therefore we need not
1097   // re-enable reference discovery for the CM ref processor.
1098   // That will be done at the start of the next marking cycle.
1099   // We also know that the STW processor should no longer
1100   // discover any new references.
1101   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1102   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1103   _ref_processor_stw->verify_no_references_recorded();
1104   _ref_processor_cm->verify_no_references_recorded();
1105 }
1106 
1107 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1108   // Post collection logging.
1109   // We should do this after we potentially resize the heap so
1110   // that all the COMMIT / UNCOMMIT events are generated before
1111   // the compaction events.
1112   print_hrm_post_compaction();
1113   heap_transition->print();
1114   print_heap_after_gc();
1115   print_heap_regions();
1116 #ifdef TRACESPINNING
1117   ParallelTaskTerminator::print_termination_counts();
1118 #endif
1119 }
1120 
1121 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1122                                          bool clear_all_soft_refs) {
1123   assert_at_safepoint_on_vm_thread();
1124 
1125   if (GCLocker::check_active_before_gc()) {
1126     // Full GC was not completed.
1127     return false;
1128   }
1129 
1130   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1131       soft_ref_policy()->should_clear_all_soft_refs();
1132 
1133   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1134   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1135 
1136   collector.prepare_collection();
1137   collector.collect();
1138   collector.complete_collection();
1139 
1140   // Full collection was successfully completed.
1141   return true;
1142 }
1143 
1144 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1145   // Currently, there is no facility in the do_full_collection(bool) API to notify
1146   // the caller that the collection did not succeed (e.g., because it was locked
1147   // out by the GC locker). So, right now, we'll ignore the return value.
1148   bool dummy = do_full_collection(true,                /* explicit_gc */
1149                                   clear_all_soft_refs);
1150 }
1151 
1152 void G1CollectedHeap::resize_heap_if_necessary() {
1153   // Capacity, free and used after the GC counted as full regions to
1154   // include the waste in the following calculations.
1155   const size_t capacity_after_gc = capacity();
1156   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1157 
1158   // This is enforced in arguments.cpp.
1159   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1160          "otherwise the code below doesn't make sense");
1161 
1162   // We don't have floating point command-line arguments
1163   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1164   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1165   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1166   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1167 
1168   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1169   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1170 
1171   // We have to be careful here as these two calculations can overflow
1172   // 32-bit size_t's.
1173   double used_after_gc_d = (double) used_after_gc;
1174   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1175   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1176 
1177   // Let's make sure that they are both under the max heap size, which
1178   // by default will make them fit into a size_t.
1179   double desired_capacity_upper_bound = (double) max_heap_size;
1180   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1181                                     desired_capacity_upper_bound);
1182   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1183                                     desired_capacity_upper_bound);
1184 
1185   // We can now safely turn them into size_t's.
1186   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1187   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1188 
1189   // This assert only makes sense here, before we adjust them
1190   // with respect to the min and max heap size.
1191   assert(minimum_desired_capacity <= maximum_desired_capacity,
1192          "minimum_desired_capacity = " SIZE_FORMAT ", "
1193          "maximum_desired_capacity = " SIZE_FORMAT,
1194          minimum_desired_capacity, maximum_desired_capacity);
1195 
1196   // Should not be greater than the heap max size. No need to adjust
1197   // it with respect to the heap min size as it's a lower bound (i.e.,
1198   // we'll try to make the capacity larger than it, not smaller).
1199   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1200   // Should not be less than the heap min size. No need to adjust it
1201   // with respect to the heap max size as it's an upper bound (i.e.,
1202   // we'll try to make the capacity smaller than it, not greater).
1203   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1204 
1205   if (capacity_after_gc < minimum_desired_capacity) {
1206     // Don't expand unless it's significant
1207     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1208 
1209     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1210                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1211                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1212                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1213 
1214     expand(expand_bytes, _workers);
1215 
1216     // No expansion, now see if we want to shrink
1217   } else if (capacity_after_gc > maximum_desired_capacity) {
1218     // Capacity too large, compute shrinking size
1219     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1220 
1221     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1222                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1223                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1224                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1225 
1226     shrink(shrink_bytes);
1227   }
1228 }
1229 
1230 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1231                                                             bool do_gc,
1232                                                             bool clear_all_soft_refs,
1233                                                             bool expect_null_mutator_alloc_region,
1234                                                             bool* gc_succeeded) {
1235   *gc_succeeded = true;
1236   // Let's attempt the allocation first.
1237   HeapWord* result =
1238     attempt_allocation_at_safepoint(word_size,
1239                                     expect_null_mutator_alloc_region);
1240   if (result != NULL) {
1241     return result;
1242   }
1243 
1244   // In a G1 heap, we're supposed to keep allocation from failing by
1245   // incremental pauses.  Therefore, at least for now, we'll favor
1246   // expansion over collection.  (This might change in the future if we can
1247   // do something smarter than full collection to satisfy a failed alloc.)
1248   result = expand_and_allocate(word_size);
1249   if (result != NULL) {
1250     return result;
1251   }
1252 
1253   if (do_gc) {
1254     // Expansion didn't work, we'll try to do a Full GC.
1255     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1256                                        clear_all_soft_refs);
1257   }
1258 
1259   return NULL;
1260 }
1261 
1262 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1263                                                      bool* succeeded) {
1264   assert_at_safepoint_on_vm_thread();
1265 
1266   // Attempts to allocate followed by Full GC.
1267   HeapWord* result =
1268     satisfy_failed_allocation_helper(word_size,
1269                                      true,  /* do_gc */
1270                                      false, /* clear_all_soft_refs */
1271                                      false, /* expect_null_mutator_alloc_region */
1272                                      succeeded);
1273 
1274   if (result != NULL || !*succeeded) {
1275     return result;
1276   }
1277 
1278   // Attempts to allocate followed by Full GC that will collect all soft references.
1279   result = satisfy_failed_allocation_helper(word_size,
1280                                             true, /* do_gc */
1281                                             true, /* clear_all_soft_refs */
1282                                             true, /* expect_null_mutator_alloc_region */
1283                                             succeeded);
1284 
1285   if (result != NULL || !*succeeded) {
1286     return result;
1287   }
1288 
1289   // Attempts to allocate, no GC
1290   result = satisfy_failed_allocation_helper(word_size,
1291                                             false, /* do_gc */
1292                                             false, /* clear_all_soft_refs */
1293                                             true,  /* expect_null_mutator_alloc_region */
1294                                             succeeded);
1295 
1296   if (result != NULL) {
1297     return result;
1298   }
1299 
1300   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1301          "Flag should have been handled and cleared prior to this point");
1302 
1303   // What else?  We might try synchronous finalization later.  If the total
1304   // space available is large enough for the allocation, then a more
1305   // complete compaction phase than we've tried so far might be
1306   // appropriate.
1307   return NULL;
1308 }
1309 
1310 // Attempting to expand the heap sufficiently
1311 // to support an allocation of the given "word_size".  If
1312 // successful, perform the allocation and return the address of the
1313 // allocated block, or else "NULL".
1314 
1315 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1316   assert_at_safepoint_on_vm_thread();
1317 
1318   _verifier->verify_region_sets_optional();
1319 
1320   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1321   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1322                             word_size * HeapWordSize);
1323 
1324 
1325   if (expand(expand_bytes, _workers)) {
1326     _hrm.verify_optional();
1327     _verifier->verify_region_sets_optional();
1328     return attempt_allocation_at_safepoint(word_size,
1329                                            false /* expect_null_mutator_alloc_region */);
1330   }
1331   return NULL;
1332 }
1333 
1334 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1335   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1336   aligned_expand_bytes = align_up(aligned_expand_bytes,
1337                                        HeapRegion::GrainBytes);
1338 
1339   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1340                             expand_bytes, aligned_expand_bytes);
1341 
1342   if (is_maximal_no_gc()) {
1343     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1344     return false;
1345   }
1346 
1347   double expand_heap_start_time_sec = os::elapsedTime();
1348   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1349   assert(regions_to_expand > 0, "Must expand by at least one region");
1350 
1351   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1352   if (expand_time_ms != NULL) {
1353     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1354   }
1355 
1356   if (expanded_by > 0) {
1357     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1358     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1359     g1_policy()->record_new_heap_size(num_regions());
1360   } else {
1361     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1362 
1363     // The expansion of the virtual storage space was unsuccessful.
1364     // Let's see if it was because we ran out of swap.
1365     if (G1ExitOnExpansionFailure &&
1366         _hrm.available() >= regions_to_expand) {
1367       // We had head room...
1368       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1369     }
1370   }
1371   return regions_to_expand > 0;
1372 }
1373 
1374 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1375   size_t aligned_shrink_bytes =
1376     ReservedSpace::page_align_size_down(shrink_bytes);
1377   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1378                                          HeapRegion::GrainBytes);
1379   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1380 
1381   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1382   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1383 
1384 
1385   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",
1386                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1387   if (num_regions_removed > 0) {
1388     g1_policy()->record_new_heap_size(num_regions());
1389   } else {
1390     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1391   }
1392 }
1393 
1394 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1395   _verifier->verify_region_sets_optional();
1396 
1397   // We should only reach here at the end of a Full GC or during Remark which
1398   // means we should not not be holding to any GC alloc regions. The method
1399   // below will make sure of that and do any remaining clean up.
1400   _allocator->abandon_gc_alloc_regions();
1401 
1402   // Instead of tearing down / rebuilding the free lists here, we
1403   // could instead use the remove_all_pending() method on free_list to
1404   // remove only the ones that we need to remove.
1405   tear_down_region_sets(true /* free_list_only */);
1406   shrink_helper(shrink_bytes);
1407   rebuild_region_sets(true /* free_list_only */);
1408 
1409   _hrm.verify_optional();
1410   _verifier->verify_region_sets_optional();
1411 }
1412 
1413 class OldRegionSetChecker : public HeapRegionSetChecker {
1414 public:
1415   void check_mt_safety() {
1416     // Master Old Set MT safety protocol:
1417     // (a) If we're at a safepoint, operations on the master old set
1418     // should be invoked:
1419     // - by the VM thread (which will serialize them), or
1420     // - by the GC workers while holding the FreeList_lock, if we're
1421     //   at a safepoint for an evacuation pause (this lock is taken
1422     //   anyway when an GC alloc region is retired so that a new one
1423     //   is allocated from the free list), or
1424     // - by the GC workers while holding the OldSets_lock, if we're at a
1425     //   safepoint for a cleanup pause.
1426     // (b) If we're not at a safepoint, operations on the master old set
1427     // should be invoked while holding the Heap_lock.
1428 
1429     if (SafepointSynchronize::is_at_safepoint()) {
1430       guarantee(Thread::current()->is_VM_thread() ||
1431                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1432                 "master old set MT safety protocol at a safepoint");
1433     } else {
1434       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1435     }
1436   }
1437   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1438   const char* get_description() { return "Old Regions"; }
1439 };
1440 
1441 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1442 public:
1443   void check_mt_safety() {
1444     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1445               "May only change archive regions during initialization or safepoint.");
1446   }
1447   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1448   const char* get_description() { return "Archive Regions"; }
1449 };
1450 
1451 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1452 public:
1453   void check_mt_safety() {
1454     // Humongous Set MT safety protocol:
1455     // (a) If we're at a safepoint, operations on the master humongous
1456     // set should be invoked by either the VM thread (which will
1457     // serialize them) or by the GC workers while holding the
1458     // OldSets_lock.
1459     // (b) If we're not at a safepoint, operations on the master
1460     // humongous set should be invoked while holding the Heap_lock.
1461 
1462     if (SafepointSynchronize::is_at_safepoint()) {
1463       guarantee(Thread::current()->is_VM_thread() ||
1464                 OldSets_lock->owned_by_self(),
1465                 "master humongous set MT safety protocol at a safepoint");
1466     } else {
1467       guarantee(Heap_lock->owned_by_self(),
1468                 "master humongous set MT safety protocol outside a safepoint");
1469     }
1470   }
1471   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1472   const char* get_description() { return "Humongous Regions"; }
1473 };
1474 
1475 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1476   CollectedHeap(),
1477   _young_gen_sampling_thread(NULL),
1478   _workers(NULL),
1479   _collector_policy(collector_policy),
1480   _card_table(NULL),
1481   _soft_ref_policy(),
1482   _old_set("Old Region Set", new OldRegionSetChecker()),
1483   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1484   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1485   _bot(NULL),
1486   _listener(),
1487   _hrm(),
1488   _allocator(NULL),
1489   _verifier(NULL),
1490   _summary_bytes_used(0),
1491   _archive_allocator(NULL),
1492   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1493   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1494   _expand_heap_after_alloc_failure(true),
1495   _g1mm(NULL),
1496   _humongous_reclaim_candidates(),
1497   _has_humongous_reclaim_candidates(false),
1498   _hr_printer(),
1499   _collector_state(),
1500   _old_marking_cycles_started(0),
1501   _old_marking_cycles_completed(0),
1502   _eden(),
1503   _survivor(),
1504   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1505   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1506   _g1_policy(new G1Policy(_gc_timer_stw)),
1507   _heap_sizing_policy(NULL),
1508   _collection_set(this, _g1_policy),
1509   _hot_card_cache(NULL),
1510   _g1_rem_set(NULL),
1511   _dirty_card_queue_set(false),
1512   _cm(NULL),
1513   _cm_thread(NULL),
1514   _cr(NULL),
1515   _task_queues(NULL),
1516   _evacuation_failed(false),
1517   _evacuation_failed_info_array(NULL),
1518   _preserved_marks_set(true /* in_c_heap */),
1519 #ifndef PRODUCT
1520   _evacuation_failure_alot_for_current_gc(false),
1521   _evacuation_failure_alot_gc_number(0),
1522   _evacuation_failure_alot_count(0),
1523 #endif
1524   _ref_processor_stw(NULL),
1525   _is_alive_closure_stw(this),
1526   _is_subject_to_discovery_stw(this),
1527   _ref_processor_cm(NULL),
1528   _is_alive_closure_cm(this),
1529   _is_subject_to_discovery_cm(this),
1530   _in_cset_fast_test() {
1531 
1532   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1533                           true /* are_GC_task_threads */,
1534                           false /* are_ConcurrentGC_threads */);
1535   _workers->initialize_workers();
1536   _verifier = new G1HeapVerifier(this);
1537 
1538   _allocator = new G1Allocator(this);
1539 
1540   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1541 
1542   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1543 
1544   // Override the default _filler_array_max_size so that no humongous filler
1545   // objects are created.
1546   _filler_array_max_size = _humongous_object_threshold_in_words;
1547 
1548   uint n_queues = ParallelGCThreads;
1549   _task_queues = new RefToScanQueueSet(n_queues);
1550 
1551   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1552 
1553   for (uint i = 0; i < n_queues; i++) {
1554     RefToScanQueue* q = new RefToScanQueue();
1555     q->initialize();
1556     _task_queues->register_queue(i, q);
1557     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1558   }
1559 
1560   // Initialize the G1EvacuationFailureALot counters and flags.
1561   NOT_PRODUCT(reset_evacuation_should_fail();)
1562 
1563   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1564 }
1565 
1566 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1567                                                                  size_t size,
1568                                                                  size_t translation_factor) {
1569   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1570   // Allocate a new reserved space, preferring to use large pages.
1571   ReservedSpace rs(size, preferred_page_size);
1572   G1RegionToSpaceMapper* result  =
1573     G1RegionToSpaceMapper::create_mapper(rs,
1574                                          size,
1575                                          rs.alignment(),
1576                                          HeapRegion::GrainBytes,
1577                                          translation_factor,
1578                                          mtGC);
1579 
1580   os::trace_page_sizes_for_requested_size(description,
1581                                           size,
1582                                           preferred_page_size,
1583                                           rs.alignment(),
1584                                           rs.base(),
1585                                           rs.size());
1586 
1587   return result;
1588 }
1589 
1590 jint G1CollectedHeap::initialize_concurrent_refinement() {
1591   jint ecode = JNI_OK;
1592   _cr = G1ConcurrentRefine::create(&ecode);
1593   return ecode;
1594 }
1595 
1596 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1597   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1598   if (_young_gen_sampling_thread->osthread() == NULL) {
1599     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1600     return JNI_ENOMEM;
1601   }
1602   return JNI_OK;
1603 }
1604 
1605 jint G1CollectedHeap::initialize() {
1606   os::enable_vtime();
1607 
1608   // Necessary to satisfy locking discipline assertions.
1609 
1610   MutexLocker x(Heap_lock);
1611 
1612   // While there are no constraints in the GC code that HeapWordSize
1613   // be any particular value, there are multiple other areas in the
1614   // system which believe this to be true (e.g. oop->object_size in some
1615   // cases incorrectly returns the size in wordSize units rather than
1616   // HeapWordSize).
1617   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1618 
1619   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1620   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1621   size_t heap_alignment = collector_policy()->heap_alignment();
1622 
1623   // Ensure that the sizes are properly aligned.
1624   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1625   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1626   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1627 
1628   // Reserve the maximum.
1629 
1630   // When compressed oops are enabled, the preferred heap base
1631   // is calculated by subtracting the requested size from the
1632   // 32Gb boundary and using the result as the base address for
1633   // heap reservation. If the requested size is not aligned to
1634   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1635   // into the ReservedHeapSpace constructor) then the actual
1636   // base of the reserved heap may end up differing from the
1637   // address that was requested (i.e. the preferred heap base).
1638   // If this happens then we could end up using a non-optimal
1639   // compressed oops mode.
1640 
1641   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1642                                                  heap_alignment);
1643 
1644   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1645 
1646   // Create the barrier set for the entire reserved region.
1647   G1CardTable* ct = new G1CardTable(reserved_region());
1648   ct->initialize();
1649   G1BarrierSet* bs = new G1BarrierSet(ct);
1650   bs->initialize();
1651   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1652   BarrierSet::set_barrier_set(bs);
1653   _card_table = ct;
1654 
1655   // Create the hot card cache.
1656   _hot_card_cache = new G1HotCardCache(this);
1657 
1658   // Carve out the G1 part of the heap.
1659   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1660   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1661   G1RegionToSpaceMapper* heap_storage =
1662     G1RegionToSpaceMapper::create_mapper(g1_rs,
1663                                          g1_rs.size(),
1664                                          page_size,
1665                                          HeapRegion::GrainBytes,
1666                                          1,
1667                                          mtJavaHeap);
1668   os::trace_page_sizes("Heap",
1669                        collector_policy()->min_heap_byte_size(),
1670                        max_byte_size,
1671                        page_size,
1672                        heap_rs.base(),
1673                        heap_rs.size());
1674   heap_storage->set_mapping_changed_listener(&_listener);
1675 
1676   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1677   G1RegionToSpaceMapper* bot_storage =
1678     create_aux_memory_mapper("Block Offset Table",
1679                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1680                              G1BlockOffsetTable::heap_map_factor());
1681 
1682   G1RegionToSpaceMapper* cardtable_storage =
1683     create_aux_memory_mapper("Card Table",
1684                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1685                              G1CardTable::heap_map_factor());
1686 
1687   G1RegionToSpaceMapper* card_counts_storage =
1688     create_aux_memory_mapper("Card Counts Table",
1689                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1690                              G1CardCounts::heap_map_factor());
1691 
1692   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1693   G1RegionToSpaceMapper* prev_bitmap_storage =
1694     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1695   G1RegionToSpaceMapper* next_bitmap_storage =
1696     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1697 
1698   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1699   _card_table->initialize(cardtable_storage);
1700   // Do later initialization work for concurrent refinement.
1701   _hot_card_cache->initialize(card_counts_storage);
1702 
1703   // 6843694 - ensure that the maximum region index can fit
1704   // in the remembered set structures.
1705   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1706   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1707 
1708   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1709   // start within the first card.
1710   guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1711   // Also create a G1 rem set.
1712   _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1713   _g1_rem_set->initialize(max_capacity(), max_regions());
1714 
1715   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1716   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1717   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1718             "too many cards per region");
1719 
1720   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1721 
1722   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1723 
1724   {
1725     HeapWord* start = _hrm.reserved().start();
1726     HeapWord* end = _hrm.reserved().end();
1727     size_t granularity = HeapRegion::GrainBytes;
1728 
1729     _in_cset_fast_test.initialize(start, end, granularity);
1730     _humongous_reclaim_candidates.initialize(start, end, granularity);
1731   }
1732 
1733   // Create the G1ConcurrentMark data structure and thread.
1734   // (Must do this late, so that "max_regions" is defined.)
1735   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1736   if (_cm == NULL || !_cm->completed_initialization()) {
1737     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1738     return JNI_ENOMEM;
1739   }
1740   _cm_thread = _cm->cm_thread();
1741 
1742   // Now expand into the initial heap size.
1743   if (!expand(init_byte_size, _workers)) {
1744     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1745     return JNI_ENOMEM;
1746   }
1747 
1748   // Perform any initialization actions delegated to the policy.
1749   g1_policy()->init(this, &_collection_set);
1750 
1751   G1BarrierSet::satb_mark_queue_set().initialize(this,
1752                                                  SATB_Q_CBL_mon,
1753                                                  SATB_Q_FL_lock,
1754                                                  G1SATBProcessCompletedThreshold,
1755                                                  G1SATBBufferEnqueueingThresholdPercent,
1756                                                  Shared_SATB_Q_lock);
1757 
1758   jint ecode = initialize_concurrent_refinement();
1759   if (ecode != JNI_OK) {
1760     return ecode;
1761   }
1762 
1763   ecode = initialize_young_gen_sampling_thread();
1764   if (ecode != JNI_OK) {
1765     return ecode;
1766   }
1767 
1768   G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1769                                                   DirtyCardQ_FL_lock,
1770                                                   (int)concurrent_refine()->yellow_zone(),
1771                                                   (int)concurrent_refine()->red_zone(),
1772                                                   Shared_DirtyCardQ_lock,
1773                                                   NULL,  // fl_owner
1774                                                   true); // init_free_ids
1775 
1776   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1777                                     DirtyCardQ_FL_lock,
1778                                     -1, // never trigger processing
1779                                     -1, // no limit on length
1780                                     Shared_DirtyCardQ_lock,
1781                                     &G1BarrierSet::dirty_card_queue_set());
1782 
1783   // Here we allocate the dummy HeapRegion that is required by the
1784   // G1AllocRegion class.
1785   HeapRegion* dummy_region = _hrm.get_dummy_region();
1786 
1787   // We'll re-use the same region whether the alloc region will
1788   // require BOT updates or not and, if it doesn't, then a non-young
1789   // region will complain that it cannot support allocations without
1790   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1791   dummy_region->set_eden();
1792   // Make sure it's full.
1793   dummy_region->set_top(dummy_region->end());
1794   G1AllocRegion::setup(this, dummy_region);
1795 
1796   _allocator->init_mutator_alloc_region();
1797 
1798   // Do create of the monitoring and management support so that
1799   // values in the heap have been properly initialized.
1800   _g1mm = new G1MonitoringSupport(this);
1801 
1802   G1StringDedup::initialize();
1803 
1804   _preserved_marks_set.init(ParallelGCThreads);
1805 
1806   _collection_set.initialize(max_regions());
1807 
1808   return JNI_OK;
1809 }
1810 
1811 void G1CollectedHeap::stop() {
1812   // Stop all concurrent threads. We do this to make sure these threads
1813   // do not continue to execute and access resources (e.g. logging)
1814   // that are destroyed during shutdown.
1815   _cr->stop();
1816   _young_gen_sampling_thread->stop();
1817   _cm_thread->stop();
1818   if (G1StringDedup::is_enabled()) {
1819     G1StringDedup::stop();
1820   }
1821 }
1822 
1823 void G1CollectedHeap::safepoint_synchronize_begin() {
1824   SuspendibleThreadSet::synchronize();
1825 }
1826 
1827 void G1CollectedHeap::safepoint_synchronize_end() {
1828   SuspendibleThreadSet::desynchronize();
1829 }
1830 
1831 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1832   return HeapRegion::max_region_size();
1833 }
1834 
1835 void G1CollectedHeap::post_initialize() {
1836   CollectedHeap::post_initialize();
1837   ref_processing_init();
1838 }
1839 
1840 void G1CollectedHeap::ref_processing_init() {
1841   // Reference processing in G1 currently works as follows:
1842   //
1843   // * There are two reference processor instances. One is
1844   //   used to record and process discovered references
1845   //   during concurrent marking; the other is used to
1846   //   record and process references during STW pauses
1847   //   (both full and incremental).
1848   // * Both ref processors need to 'span' the entire heap as
1849   //   the regions in the collection set may be dotted around.
1850   //
1851   // * For the concurrent marking ref processor:
1852   //   * Reference discovery is enabled at initial marking.
1853   //   * Reference discovery is disabled and the discovered
1854   //     references processed etc during remarking.
1855   //   * Reference discovery is MT (see below).
1856   //   * Reference discovery requires a barrier (see below).
1857   //   * Reference processing may or may not be MT
1858   //     (depending on the value of ParallelRefProcEnabled
1859   //     and ParallelGCThreads).
1860   //   * A full GC disables reference discovery by the CM
1861   //     ref processor and abandons any entries on it's
1862   //     discovered lists.
1863   //
1864   // * For the STW processor:
1865   //   * Non MT discovery is enabled at the start of a full GC.
1866   //   * Processing and enqueueing during a full GC is non-MT.
1867   //   * During a full GC, references are processed after marking.
1868   //
1869   //   * Discovery (may or may not be MT) is enabled at the start
1870   //     of an incremental evacuation pause.
1871   //   * References are processed near the end of a STW evacuation pause.
1872   //   * For both types of GC:
1873   //     * Discovery is atomic - i.e. not concurrent.
1874   //     * Reference discovery will not need a barrier.
1875 
1876   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1877 
1878   // Concurrent Mark ref processor
1879   _ref_processor_cm =
1880     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1881                            mt_processing,                                  // mt processing
1882                            ParallelGCThreads,                              // degree of mt processing
1883                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1884                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1885                            false,                                          // Reference discovery is not atomic
1886                            &_is_alive_closure_cm,                          // is alive closure
1887                            true);                                          // allow changes to number of processing threads
1888 
1889   // STW ref processor
1890   _ref_processor_stw =
1891     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1892                            mt_processing,                        // mt processing
1893                            ParallelGCThreads,                    // degree of mt processing
1894                            (ParallelGCThreads > 1),              // mt discovery
1895                            ParallelGCThreads,                    // degree of mt discovery
1896                            true,                                 // Reference discovery is atomic
1897                            &_is_alive_closure_stw,               // is alive closure
1898                            true);                                // allow changes to number of processing threads
1899 }
1900 
1901 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1902   return _collector_policy;
1903 }
1904 
1905 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1906   return &_soft_ref_policy;
1907 }
1908 
1909 size_t G1CollectedHeap::capacity() const {
1910   return _hrm.length() * HeapRegion::GrainBytes;
1911 }
1912 
1913 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1914   return _hrm.total_free_bytes();
1915 }
1916 
1917 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1918   _hot_card_cache->drain(cl, worker_i);
1919 }
1920 
1921 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1922   DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1923   size_t n_completed_buffers = 0;
1924   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1925     n_completed_buffers++;
1926   }
1927   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1928   dcqs.clear_n_completed_buffers();
1929   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1930 }
1931 
1932 // Computes the sum of the storage used by the various regions.
1933 size_t G1CollectedHeap::used() const {
1934   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1935   if (_archive_allocator != NULL) {
1936     result += _archive_allocator->used();
1937   }
1938   return result;
1939 }
1940 
1941 size_t G1CollectedHeap::used_unlocked() const {
1942   return _summary_bytes_used;
1943 }
1944 
1945 class SumUsedClosure: public HeapRegionClosure {
1946   size_t _used;
1947 public:
1948   SumUsedClosure() : _used(0) {}
1949   bool do_heap_region(HeapRegion* r) {
1950     _used += r->used();
1951     return false;
1952   }
1953   size_t result() { return _used; }
1954 };
1955 
1956 size_t G1CollectedHeap::recalculate_used() const {
1957   SumUsedClosure blk;
1958   heap_region_iterate(&blk);
1959   return blk.result();
1960 }
1961 
1962 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1963   switch (cause) {
1964     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1965     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1966     case GCCause::_wb_conc_mark:                        return true;
1967     default :                                           return false;
1968   }
1969 }
1970 
1971 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1972   switch (cause) {
1973     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
1974     case GCCause::_g1_humongous_allocation: return true;
1975     default:                                return is_user_requested_concurrent_full_gc(cause);
1976   }
1977 }
1978 
1979 #ifndef PRODUCT
1980 void G1CollectedHeap::allocate_dummy_regions() {
1981   // Let's fill up most of the region
1982   size_t word_size = HeapRegion::GrainWords - 1024;
1983   // And as a result the region we'll allocate will be humongous.
1984   guarantee(is_humongous(word_size), "sanity");
1985 
1986   // _filler_array_max_size is set to humongous object threshold
1987   // but temporarily change it to use CollectedHeap::fill_with_object().
1988   SizeTFlagSetting fs(_filler_array_max_size, word_size);
1989 
1990   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1991     // Let's use the existing mechanism for the allocation
1992     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1993     if (dummy_obj != NULL) {
1994       MemRegion mr(dummy_obj, word_size);
1995       CollectedHeap::fill_with_object(mr);
1996     } else {
1997       // If we can't allocate once, we probably cannot allocate
1998       // again. Let's get out of the loop.
1999       break;
2000     }
2001   }
2002 }
2003 #endif // !PRODUCT
2004 
2005 void G1CollectedHeap::increment_old_marking_cycles_started() {
2006   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2007          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2008          "Wrong marking cycle count (started: %d, completed: %d)",
2009          _old_marking_cycles_started, _old_marking_cycles_completed);
2010 
2011   _old_marking_cycles_started++;
2012 }
2013 
2014 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2015   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2016 
2017   // We assume that if concurrent == true, then the caller is a
2018   // concurrent thread that was joined the Suspendible Thread
2019   // Set. If there's ever a cheap way to check this, we should add an
2020   // assert here.
2021 
2022   // Given that this method is called at the end of a Full GC or of a
2023   // concurrent cycle, and those can be nested (i.e., a Full GC can
2024   // interrupt a concurrent cycle), the number of full collections
2025   // completed should be either one (in the case where there was no
2026   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2027   // behind the number of full collections started.
2028 
2029   // This is the case for the inner caller, i.e. a Full GC.
2030   assert(concurrent ||
2031          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2032          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2033          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2034          "is inconsistent with _old_marking_cycles_completed = %u",
2035          _old_marking_cycles_started, _old_marking_cycles_completed);
2036 
2037   // This is the case for the outer caller, i.e. the concurrent cycle.
2038   assert(!concurrent ||
2039          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2040          "for outer caller (concurrent cycle): "
2041          "_old_marking_cycles_started = %u "
2042          "is inconsistent with _old_marking_cycles_completed = %u",
2043          _old_marking_cycles_started, _old_marking_cycles_completed);
2044 
2045   _old_marking_cycles_completed += 1;
2046 
2047   // We need to clear the "in_progress" flag in the CM thread before
2048   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2049   // is set) so that if a waiter requests another System.gc() it doesn't
2050   // incorrectly see that a marking cycle is still in progress.
2051   if (concurrent) {
2052     _cm_thread->set_idle();
2053   }
2054 
2055   // This notify_all() will ensure that a thread that called
2056   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2057   // and it's waiting for a full GC to finish will be woken up. It is
2058   // waiting in VM_G1CollectForAllocation::doit_epilogue().
2059   FullGCCount_lock->notify_all();
2060 }
2061 
2062 void G1CollectedHeap::collect(GCCause::Cause cause) {
2063   assert_heap_not_locked();
2064 
2065   uint gc_count_before;
2066   uint old_marking_count_before;
2067   uint full_gc_count_before;
2068   bool retry_gc;
2069 
2070   do {
2071     retry_gc = false;
2072 
2073     {
2074       MutexLocker ml(Heap_lock);
2075 
2076       // Read the GC count while holding the Heap_lock
2077       gc_count_before = total_collections();
2078       full_gc_count_before = total_full_collections();
2079       old_marking_count_before = _old_marking_cycles_started;
2080     }
2081 
2082     if (should_do_concurrent_full_gc(cause)) {
2083       // Schedule an initial-mark evacuation pause that will start a
2084       // concurrent cycle. We're setting word_size to 0 which means that
2085       // we are not requesting a post-GC allocation.
2086       VM_G1CollectForAllocation op(0,     /* word_size */
2087                                    gc_count_before,
2088                                    cause,
2089                                    true,  /* should_initiate_conc_mark */
2090                                    g1_policy()->max_pause_time_ms());
2091       VMThread::execute(&op);
2092       if (!op.pause_succeeded()) {
2093         if (old_marking_count_before == _old_marking_cycles_started) {
2094           retry_gc = op.should_retry_gc();
2095         } else {
2096           // A Full GC happened while we were trying to schedule the
2097           // initial-mark GC. No point in starting a new cycle given
2098           // that the whole heap was collected anyway.
2099         }
2100 
2101         if (retry_gc) {
2102           if (GCLocker::is_active_and_needs_gc()) {
2103             GCLocker::stall_until_clear();
2104           }
2105         }
2106       }
2107     } else {
2108       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2109           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2110 
2111         // Schedule a standard evacuation pause. We're setting word_size
2112         // to 0 which means that we are not requesting a post-GC allocation.
2113         VM_G1CollectForAllocation op(0,     /* word_size */
2114                                      gc_count_before,
2115                                      cause,
2116                                      false, /* should_initiate_conc_mark */
2117                                      g1_policy()->max_pause_time_ms());
2118         VMThread::execute(&op);
2119       } else {
2120         // Schedule a Full GC.
2121         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2122         VMThread::execute(&op);
2123       }
2124     }
2125   } while (retry_gc);
2126 }
2127 
2128 bool G1CollectedHeap::is_in(const void* p) const {
2129   if (_hrm.reserved().contains(p)) {
2130     // Given that we know that p is in the reserved space,
2131     // heap_region_containing() should successfully
2132     // return the containing region.
2133     HeapRegion* hr = heap_region_containing(p);
2134     return hr->is_in(p);
2135   } else {
2136     return false;
2137   }
2138 }
2139 
2140 #ifdef ASSERT
2141 bool G1CollectedHeap::is_in_exact(const void* p) const {
2142   bool contains = reserved_region().contains(p);
2143   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2144   if (contains && available) {
2145     return true;
2146   } else {
2147     return false;
2148   }
2149 }
2150 #endif
2151 
2152 // Iteration functions.
2153 
2154 // Iterates an ObjectClosure over all objects within a HeapRegion.
2155 
2156 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2157   ObjectClosure* _cl;
2158 public:
2159   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2160   bool do_heap_region(HeapRegion* r) {
2161     if (!r->is_continues_humongous()) {
2162       r->object_iterate(_cl);
2163     }
2164     return false;
2165   }
2166 };
2167 
2168 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2169   IterateObjectClosureRegionClosure blk(cl);
2170   heap_region_iterate(&blk);
2171 }
2172 
2173 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2174   _hrm.iterate(cl);
2175 }
2176 
2177 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2178                                                                  HeapRegionClaimer *hrclaimer,
2179                                                                  uint worker_id) const {
2180   _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2181 }
2182 
2183 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2184                                                          HeapRegionClaimer *hrclaimer) const {
2185   _hrm.par_iterate(cl, hrclaimer, 0);
2186 }
2187 
2188 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2189   _collection_set.iterate(cl);
2190 }
2191 
2192 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2193   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2194 }
2195 
2196 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2197   HeapRegion* hr = heap_region_containing(addr);
2198   return hr->block_start(addr);
2199 }
2200 
2201 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2202   HeapRegion* hr = heap_region_containing(addr);
2203   return hr->block_size(addr);
2204 }
2205 
2206 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2207   HeapRegion* hr = heap_region_containing(addr);
2208   return hr->block_is_obj(addr);
2209 }
2210 
2211 bool G1CollectedHeap::supports_tlab_allocation() const {
2212   return true;
2213 }
2214 
2215 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2216   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2217 }
2218 
2219 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2220   return _eden.length() * HeapRegion::GrainBytes;
2221 }
2222 
2223 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2224 // must be equal to the humongous object limit.
2225 size_t G1CollectedHeap::max_tlab_size() const {
2226   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2227 }
2228 
2229 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2230   return _allocator->unsafe_max_tlab_alloc();
2231 }
2232 
2233 size_t G1CollectedHeap::max_capacity() const {
2234   return _hrm.reserved().byte_size();
2235 }
2236 
2237 jlong G1CollectedHeap::millis_since_last_gc() {
2238   // See the notes in GenCollectedHeap::millis_since_last_gc()
2239   // for more information about the implementation.
2240   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2241     _g1_policy->collection_pause_end_millis();
2242   if (ret_val < 0) {
2243     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2244       ". returning zero instead.", ret_val);
2245     return 0;
2246   }
2247   return ret_val;
2248 }
2249 
2250 void G1CollectedHeap::deduplicate_string(oop str) {
2251   assert(java_lang_String::is_instance(str), "invariant");
2252 
2253   if (G1StringDedup::is_enabled()) {
2254     G1StringDedup::deduplicate(str);
2255   }
2256 }
2257 
2258 void G1CollectedHeap::prepare_for_verify() {
2259   _verifier->prepare_for_verify();
2260 }
2261 
2262 void G1CollectedHeap::verify(VerifyOption vo) {
2263   _verifier->verify(vo);
2264 }
2265 
2266 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2267   return true;
2268 }
2269 
2270 const char* const* G1CollectedHeap::concurrent_phases() const {
2271   return _cm_thread->concurrent_phases();
2272 }
2273 
2274 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2275   return _cm_thread->request_concurrent_phase(phase);
2276 }
2277 
2278 class PrintRegionClosure: public HeapRegionClosure {
2279   outputStream* _st;
2280 public:
2281   PrintRegionClosure(outputStream* st) : _st(st) {}
2282   bool do_heap_region(HeapRegion* r) {
2283     r->print_on(_st);
2284     return false;
2285   }
2286 };
2287 
2288 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2289                                        const HeapRegion* hr,
2290                                        const VerifyOption vo) const {
2291   switch (vo) {
2292   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2293   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2294   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2295   default:                            ShouldNotReachHere();
2296   }
2297   return false; // keep some compilers happy
2298 }
2299 
2300 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2301                                        const VerifyOption vo) const {
2302   switch (vo) {
2303   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2304   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2305   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2306   default:                            ShouldNotReachHere();
2307   }
2308   return false; // keep some compilers happy
2309 }
2310 
2311 void G1CollectedHeap::print_heap_regions() const {
2312   LogTarget(Trace, gc, heap, region) lt;
2313   if (lt.is_enabled()) {
2314     LogStream ls(lt);
2315     print_regions_on(&ls);
2316   }
2317 }
2318 
2319 void G1CollectedHeap::print_on(outputStream* st) const {
2320   st->print(" %-20s", "garbage-first heap");
2321   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2322             capacity()/K, used_unlocked()/K);
2323   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2324             p2i(_hrm.reserved().start()),
2325             p2i(_hrm.reserved().end()));
2326   st->cr();
2327   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2328   uint young_regions = young_regions_count();
2329   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2330             (size_t) young_regions * HeapRegion::GrainBytes / K);
2331   uint survivor_regions = survivor_regions_count();
2332   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2333             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2334   st->cr();
2335   MetaspaceUtils::print_on(st);
2336 }
2337 
2338 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2339   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2340                "HS=humongous(starts), HC=humongous(continues), "
2341                "CS=collection set, F=free, A=archive, "
2342                "TAMS=top-at-mark-start (previous, next)");
2343   PrintRegionClosure blk(st);
2344   heap_region_iterate(&blk);
2345 }
2346 
2347 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2348   print_on(st);
2349 
2350   // Print the per-region information.
2351   print_regions_on(st);
2352 }
2353 
2354 void G1CollectedHeap::print_on_error(outputStream* st) const {
2355   this->CollectedHeap::print_on_error(st);
2356 
2357   if (_cm != NULL) {
2358     st->cr();
2359     _cm->print_on_error(st);
2360   }
2361 }
2362 
2363 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2364   workers()->print_worker_threads_on(st);
2365   _cm_thread->print_on(st);
2366   st->cr();
2367   _cm->print_worker_threads_on(st);
2368   _cr->print_threads_on(st);
2369   _young_gen_sampling_thread->print_on(st);
2370   if (G1StringDedup::is_enabled()) {
2371     G1StringDedup::print_worker_threads_on(st);
2372   }
2373 }
2374 
2375 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2376   workers()->threads_do(tc);
2377   tc->do_thread(_cm_thread);
2378   _cm->threads_do(tc);
2379   _cr->threads_do(tc);
2380   tc->do_thread(_young_gen_sampling_thread);
2381   if (G1StringDedup::is_enabled()) {
2382     G1StringDedup::threads_do(tc);
2383   }
2384 }
2385 
2386 void G1CollectedHeap::print_tracing_info() const {
2387   g1_rem_set()->print_summary_info();
2388   concurrent_mark()->print_summary_info();
2389 }
2390 
2391 #ifndef PRODUCT
2392 // Helpful for debugging RSet issues.
2393 
2394 class PrintRSetsClosure : public HeapRegionClosure {
2395 private:
2396   const char* _msg;
2397   size_t _occupied_sum;
2398 
2399 public:
2400   bool do_heap_region(HeapRegion* r) {
2401     HeapRegionRemSet* hrrs = r->rem_set();
2402     size_t occupied = hrrs->occupied();
2403     _occupied_sum += occupied;
2404 
2405     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2406     if (occupied == 0) {
2407       tty->print_cr("  RSet is empty");
2408     } else {
2409       hrrs->print();
2410     }
2411     tty->print_cr("----------");
2412     return false;
2413   }
2414 
2415   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2416     tty->cr();
2417     tty->print_cr("========================================");
2418     tty->print_cr("%s", msg);
2419     tty->cr();
2420   }
2421 
2422   ~PrintRSetsClosure() {
2423     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2424     tty->print_cr("========================================");
2425     tty->cr();
2426   }
2427 };
2428 
2429 void G1CollectedHeap::print_cset_rsets() {
2430   PrintRSetsClosure cl("Printing CSet RSets");
2431   collection_set_iterate(&cl);
2432 }
2433 
2434 void G1CollectedHeap::print_all_rsets() {
2435   PrintRSetsClosure cl("Printing All RSets");;
2436   heap_region_iterate(&cl);
2437 }
2438 #endif // PRODUCT
2439 
2440 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2441 
2442   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2443   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2444   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2445 
2446   size_t eden_capacity_bytes =
2447     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2448 
2449   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2450   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2451                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2452 }
2453 
2454 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2455   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2456                        stats->unused(), stats->used(), stats->region_end_waste(),
2457                        stats->regions_filled(), stats->direct_allocated(),
2458                        stats->failure_used(), stats->failure_waste());
2459 }
2460 
2461 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2462   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2463   gc_tracer->report_gc_heap_summary(when, heap_summary);
2464 
2465   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2466   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2467 }
2468 
2469 G1CollectedHeap* G1CollectedHeap::heap() {
2470   CollectedHeap* heap = Universe::heap();
2471   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2472   assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2473   return (G1CollectedHeap*)heap;
2474 }
2475 
2476 void G1CollectedHeap::gc_prologue(bool full) {
2477   // always_do_update_barrier = false;
2478   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2479 
2480   // This summary needs to be printed before incrementing total collections.
2481   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2482 
2483   // Update common counters.
2484   increment_total_collections(full /* full gc */);
2485   if (full) {
2486     increment_old_marking_cycles_started();
2487   }
2488 
2489   // Fill TLAB's and such
2490   double start = os::elapsedTime();
2491   ensure_parsability(true);
2492   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2493 }
2494 
2495 void G1CollectedHeap::gc_epilogue(bool full) {
2496   // Update common counters.
2497   if (full) {
2498     // Update the number of full collections that have been completed.
2499     increment_old_marking_cycles_completed(false /* concurrent */);
2500   }
2501 
2502   // We are at the end of the GC. Total collections has already been increased.
2503   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2504 
2505   // FIXME: what is this about?
2506   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2507   // is set.
2508 #if COMPILER2_OR_JVMCI
2509   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2510 #endif
2511   // always_do_update_barrier = true;
2512 
2513   double start = os::elapsedTime();
2514   resize_all_tlabs();
2515   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2516 
2517   MemoryService::track_memory_usage();
2518   // We have just completed a GC. Update the soft reference
2519   // policy with the new heap occupancy
2520   Universe::update_heap_info_at_gc();
2521 }
2522 
2523 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2524                                                uint gc_count_before,
2525                                                bool* succeeded,
2526                                                GCCause::Cause gc_cause) {
2527   assert_heap_not_locked_and_not_at_safepoint();
2528   VM_G1CollectForAllocation op(word_size,
2529                                gc_count_before,
2530                                gc_cause,
2531                                false, /* should_initiate_conc_mark */
2532                                g1_policy()->max_pause_time_ms());
2533   VMThread::execute(&op);
2534 
2535   HeapWord* result = op.result();
2536   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2537   assert(result == NULL || ret_succeeded,
2538          "the result should be NULL if the VM did not succeed");
2539   *succeeded = ret_succeeded;
2540 
2541   assert_heap_not_locked();
2542   return result;
2543 }
2544 
2545 void G1CollectedHeap::do_concurrent_mark() {
2546   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2547   if (!_cm_thread->in_progress()) {
2548     _cm_thread->set_started();
2549     CGC_lock->notify();
2550   }
2551 }
2552 
2553 size_t G1CollectedHeap::pending_card_num() {
2554   size_t extra_cards = 0;
2555   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2556     DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2557     extra_cards += dcq.size();
2558   }
2559   DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2560   size_t buffer_size = dcqs.buffer_size();
2561   size_t buffer_num = dcqs.completed_buffers_num();
2562 
2563   return buffer_size * buffer_num + extra_cards;
2564 }
2565 
2566 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2567   // We don't nominate objects with many remembered set entries, on
2568   // the assumption that such objects are likely still live.
2569   HeapRegionRemSet* rem_set = r->rem_set();
2570 
2571   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2572          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2573          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2574 }
2575 
2576 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2577  private:
2578   size_t _total_humongous;
2579   size_t _candidate_humongous;
2580 
2581   DirtyCardQueue _dcq;
2582 
2583   bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2584     assert(region->is_starts_humongous(), "Must start a humongous object");
2585 
2586     oop obj = oop(region->bottom());
2587 
2588     // Dead objects cannot be eager reclaim candidates. Due to class
2589     // unloading it is unsafe to query their classes so we return early.
2590     if (g1h->is_obj_dead(obj, region)) {
2591       return false;
2592     }
2593 
2594     // If we do not have a complete remembered set for the region, then we can
2595     // not be sure that we have all references to it.
2596     if (!region->rem_set()->is_complete()) {
2597       return false;
2598     }
2599     // Candidate selection must satisfy the following constraints
2600     // while concurrent marking is in progress:
2601     //
2602     // * In order to maintain SATB invariants, an object must not be
2603     // reclaimed if it was allocated before the start of marking and
2604     // has not had its references scanned.  Such an object must have
2605     // its references (including type metadata) scanned to ensure no
2606     // live objects are missed by the marking process.  Objects
2607     // allocated after the start of concurrent marking don't need to
2608     // be scanned.
2609     //
2610     // * An object must not be reclaimed if it is on the concurrent
2611     // mark stack.  Objects allocated after the start of concurrent
2612     // marking are never pushed on the mark stack.
2613     //
2614     // Nominating only objects allocated after the start of concurrent
2615     // marking is sufficient to meet both constraints.  This may miss
2616     // some objects that satisfy the constraints, but the marking data
2617     // structures don't support efficiently performing the needed
2618     // additional tests or scrubbing of the mark stack.
2619     //
2620     // However, we presently only nominate is_typeArray() objects.
2621     // A humongous object containing references induces remembered
2622     // set entries on other regions.  In order to reclaim such an
2623     // object, those remembered sets would need to be cleaned up.
2624     //
2625     // We also treat is_typeArray() objects specially, allowing them
2626     // to be reclaimed even if allocated before the start of
2627     // concurrent mark.  For this we rely on mark stack insertion to
2628     // exclude is_typeArray() objects, preventing reclaiming an object
2629     // that is in the mark stack.  We also rely on the metadata for
2630     // such objects to be built-in and so ensured to be kept live.
2631     // Frequent allocation and drop of large binary blobs is an
2632     // important use case for eager reclaim, and this special handling
2633     // may reduce needed headroom.
2634 
2635     return obj->is_typeArray() &&
2636            g1h->is_potential_eager_reclaim_candidate(region);
2637   }
2638 
2639  public:
2640   RegisterHumongousWithInCSetFastTestClosure()
2641   : _total_humongous(0),
2642     _candidate_humongous(0),
2643     _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2644   }
2645 
2646   virtual bool do_heap_region(HeapRegion* r) {
2647     if (!r->is_starts_humongous()) {
2648       return false;
2649     }
2650     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2651 
2652     bool is_candidate = humongous_region_is_candidate(g1h, r);
2653     uint rindex = r->hrm_index();
2654     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2655     if (is_candidate) {
2656       _candidate_humongous++;
2657       g1h->register_humongous_region_with_cset(rindex);
2658       // Is_candidate already filters out humongous object with large remembered sets.
2659       // If we have a humongous object with a few remembered sets, we simply flush these
2660       // remembered set entries into the DCQS. That will result in automatic
2661       // re-evaluation of their remembered set entries during the following evacuation
2662       // phase.
2663       if (!r->rem_set()->is_empty()) {
2664         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2665                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2666         G1CardTable* ct = g1h->card_table();
2667         HeapRegionRemSetIterator hrrs(r->rem_set());
2668         size_t card_index;
2669         while (hrrs.has_next(card_index)) {
2670           jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2671           // The remembered set might contain references to already freed
2672           // regions. Filter out such entries to avoid failing card table
2673           // verification.
2674           if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2675             if (*card_ptr != G1CardTable::dirty_card_val()) {
2676               *card_ptr = G1CardTable::dirty_card_val();
2677               _dcq.enqueue(card_ptr);
2678             }
2679           }
2680         }
2681         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2682                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2683                hrrs.n_yielded(), r->rem_set()->occupied());
2684         // We should only clear the card based remembered set here as we will not
2685         // implicitly rebuild anything else during eager reclaim. Note that at the moment
2686         // (and probably never) we do not enter this path if there are other kind of
2687         // remembered sets for this region.
2688         r->rem_set()->clear_locked(true /* only_cardset */);
2689         // Clear_locked() above sets the state to Empty. However we want to continue
2690         // collecting remembered set entries for humongous regions that were not
2691         // reclaimed.
2692         r->rem_set()->set_state_complete();
2693       }
2694       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2695     }
2696     _total_humongous++;
2697 
2698     return false;
2699   }
2700 
2701   size_t total_humongous() const { return _total_humongous; }
2702   size_t candidate_humongous() const { return _candidate_humongous; }
2703 
2704   void flush_rem_set_entries() { _dcq.flush(); }
2705 };
2706 
2707 void G1CollectedHeap::register_humongous_regions_with_cset() {
2708   if (!G1EagerReclaimHumongousObjects) {
2709     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2710     return;
2711   }
2712   double time = os::elapsed_counter();
2713 
2714   // Collect reclaim candidate information and register candidates with cset.
2715   RegisterHumongousWithInCSetFastTestClosure cl;
2716   heap_region_iterate(&cl);
2717 
2718   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2719   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2720                                                                   cl.total_humongous(),
2721                                                                   cl.candidate_humongous());
2722   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2723 
2724   // Finally flush all remembered set entries to re-check into the global DCQS.
2725   cl.flush_rem_set_entries();
2726 }
2727 
2728 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2729   public:
2730     bool do_heap_region(HeapRegion* hr) {
2731       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2732         hr->verify_rem_set();
2733       }
2734       return false;
2735     }
2736 };
2737 
2738 uint G1CollectedHeap::num_task_queues() const {
2739   return _task_queues->size();
2740 }
2741 
2742 #if TASKQUEUE_STATS
2743 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2744   st->print_raw_cr("GC Task Stats");
2745   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2746   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2747 }
2748 
2749 void G1CollectedHeap::print_taskqueue_stats() const {
2750   if (!log_is_enabled(Trace, gc, task, stats)) {
2751     return;
2752   }
2753   Log(gc, task, stats) log;
2754   ResourceMark rm;
2755   LogStream ls(log.trace());
2756   outputStream* st = &ls;
2757 
2758   print_taskqueue_stats_hdr(st);
2759 
2760   TaskQueueStats totals;
2761   const uint n = num_task_queues();
2762   for (uint i = 0; i < n; ++i) {
2763     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2764     totals += task_queue(i)->stats;
2765   }
2766   st->print_raw("tot "); totals.print(st); st->cr();
2767 
2768   DEBUG_ONLY(totals.verify());
2769 }
2770 
2771 void G1CollectedHeap::reset_taskqueue_stats() {
2772   const uint n = num_task_queues();
2773   for (uint i = 0; i < n; ++i) {
2774     task_queue(i)->stats.reset();
2775   }
2776 }
2777 #endif // TASKQUEUE_STATS
2778 
2779 void G1CollectedHeap::wait_for_root_region_scanning() {
2780   double scan_wait_start = os::elapsedTime();
2781   // We have to wait until the CM threads finish scanning the
2782   // root regions as it's the only way to ensure that all the
2783   // objects on them have been correctly scanned before we start
2784   // moving them during the GC.
2785   bool waited = _cm->root_regions()->wait_until_scan_finished();
2786   double wait_time_ms = 0.0;
2787   if (waited) {
2788     double scan_wait_end = os::elapsedTime();
2789     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2790   }
2791   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2792 }
2793 
2794 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2795 private:
2796   G1HRPrinter* _hr_printer;
2797 public:
2798   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2799 
2800   virtual bool do_heap_region(HeapRegion* r) {
2801     _hr_printer->cset(r);
2802     return false;
2803   }
2804 };
2805 
2806 void G1CollectedHeap::start_new_collection_set() {
2807   collection_set()->start_incremental_building();
2808 
2809   clear_cset_fast_test();
2810 
2811   guarantee(_eden.length() == 0, "eden should have been cleared");
2812   g1_policy()->transfer_survivors_to_cset(survivor());
2813 }
2814 
2815 bool
2816 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2817   assert_at_safepoint_on_vm_thread();
2818   guarantee(!is_gc_active(), "collection is not reentrant");
2819 
2820   if (GCLocker::check_active_before_gc()) {
2821     return false;
2822   }
2823 
2824   _gc_timer_stw->register_gc_start();
2825 
2826   GCIdMark gc_id_mark;
2827   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2828 
2829   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2830   ResourceMark rm;
2831 
2832   g1_policy()->note_gc_start();
2833 
2834   wait_for_root_region_scanning();
2835 
2836   print_heap_before_gc();
2837   print_heap_regions();
2838   trace_heap_before_gc(_gc_tracer_stw);
2839 
2840   _verifier->verify_region_sets_optional();
2841   _verifier->verify_dirty_young_regions();
2842 
2843   // We should not be doing initial mark unless the conc mark thread is running
2844   if (!_cm_thread->should_terminate()) {
2845     // This call will decide whether this pause is an initial-mark
2846     // pause. If it is, in_initial_mark_gc() will return true
2847     // for the duration of this pause.
2848     g1_policy()->decide_on_conc_mark_initiation();
2849   }
2850 
2851   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2852   assert(!collector_state()->in_initial_mark_gc() ||
2853           collector_state()->in_young_only_phase(), "sanity");
2854 
2855   // We also do not allow mixed GCs during marking.
2856   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2857 
2858   // Record whether this pause is an initial mark. When the current
2859   // thread has completed its logging output and it's safe to signal
2860   // the CM thread, the flag's value in the policy has been reset.
2861   bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2862 
2863   // Inner scope for scope based logging, timers, and stats collection
2864   {
2865     EvacuationInfo evacuation_info;
2866 
2867     if (collector_state()->in_initial_mark_gc()) {
2868       // We are about to start a marking cycle, so we increment the
2869       // full collection counter.
2870       increment_old_marking_cycles_started();
2871       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2872     }
2873 
2874     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2875 
2876     GCTraceCPUTime tcpu;
2877 
2878     G1HeapVerifier::G1VerifyType verify_type;
2879     FormatBuffer<> gc_string("Pause Young ");
2880     if (collector_state()->in_initial_mark_gc()) {
2881       gc_string.append("(Concurrent Start)");
2882       verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2883     } else if (collector_state()->in_young_only_phase()) {
2884       if (collector_state()->in_young_gc_before_mixed()) {
2885         gc_string.append("(Prepare Mixed)");
2886       } else {
2887         gc_string.append("(Normal)");
2888       }
2889       verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2890     } else {
2891       gc_string.append("(Mixed)");
2892       verify_type = G1HeapVerifier::G1VerifyMixed;
2893     }
2894     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2895 
2896     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2897                                                                   workers()->active_workers(),
2898                                                                   Threads::number_of_non_daemon_threads());
2899     active_workers = workers()->update_active_workers(active_workers);
2900     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2901 
2902     G1MonitoringScope ms(g1mm(),
2903                          false /* full_gc */,
2904                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2905 
2906     G1HeapTransition heap_transition(this);
2907     size_t heap_used_bytes_before_gc = used();
2908 
2909     // Don't dynamically change the number of GC threads this early.  A value of
2910     // 0 is used to indicate serial work.  When parallel work is done,
2911     // it will be set.
2912 
2913     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2914       IsGCActiveMark x;
2915 
2916       gc_prologue(false);
2917 
2918       if (VerifyRememberedSets) {
2919         log_info(gc, verify)("[Verifying RemSets before GC]");
2920         VerifyRegionRemSetClosure v_cl;
2921         heap_region_iterate(&v_cl);
2922       }
2923 
2924       _verifier->verify_before_gc(verify_type);
2925 
2926       _verifier->check_bitmaps("GC Start");
2927 
2928 #if COMPILER2_OR_JVMCI
2929       DerivedPointerTable::clear();
2930 #endif
2931 
2932       // Please see comment in g1CollectedHeap.hpp and
2933       // G1CollectedHeap::ref_processing_init() to see how
2934       // reference processing currently works in G1.
2935 
2936       // Enable discovery in the STW reference processor
2937       _ref_processor_stw->enable_discovery();
2938 
2939       {
2940         // We want to temporarily turn off discovery by the
2941         // CM ref processor, if necessary, and turn it back on
2942         // on again later if we do. Using a scoped
2943         // NoRefDiscovery object will do this.
2944         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2945 
2946         // Forget the current alloc region (we might even choose it to be part
2947         // of the collection set!).
2948         _allocator->release_mutator_alloc_region();
2949 
2950         // This timing is only used by the ergonomics to handle our pause target.
2951         // It is unclear why this should not include the full pause. We will
2952         // investigate this in CR 7178365.
2953         //
2954         // Preserving the old comment here if that helps the investigation:
2955         //
2956         // The elapsed time induced by the start time below deliberately elides
2957         // the possible verification above.
2958         double sample_start_time_sec = os::elapsedTime();
2959 
2960         g1_policy()->record_collection_pause_start(sample_start_time_sec);
2961 
2962         if (collector_state()->in_initial_mark_gc()) {
2963           concurrent_mark()->pre_initial_mark();
2964         }
2965 
2966         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2967 
2968         evacuation_info.set_collectionset_regions(collection_set()->region_length());
2969 
2970         // Make sure the remembered sets are up to date. This needs to be
2971         // done before register_humongous_regions_with_cset(), because the
2972         // remembered sets are used there to choose eager reclaim candidates.
2973         // If the remembered sets are not up to date we might miss some
2974         // entries that need to be handled.
2975         g1_rem_set()->cleanupHRRS();
2976 
2977         register_humongous_regions_with_cset();
2978 
2979         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2980 
2981         // We call this after finalize_cset() to
2982         // ensure that the CSet has been finalized.
2983         _cm->verify_no_cset_oops();
2984 
2985         if (_hr_printer.is_active()) {
2986           G1PrintCollectionSetClosure cl(&_hr_printer);
2987           _collection_set.iterate(&cl);
2988         }
2989 
2990         // Initialize the GC alloc regions.
2991         _allocator->init_gc_alloc_regions(evacuation_info);
2992 
2993         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2994         pre_evacuate_collection_set();
2995 
2996         // Actually do the work...
2997         evacuate_collection_set(&per_thread_states);
2998 
2999         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3000 
3001         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3002         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3003 
3004         eagerly_reclaim_humongous_regions();
3005 
3006         record_obj_copy_mem_stats();
3007         _survivor_evac_stats.adjust_desired_plab_sz();
3008         _old_evac_stats.adjust_desired_plab_sz();
3009 
3010         double start = os::elapsedTime();
3011         start_new_collection_set();
3012         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3013 
3014         if (evacuation_failed()) {
3015           double recalculate_used_start = os::elapsedTime();
3016           set_used(recalculate_used());
3017           g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3018 
3019           if (_archive_allocator != NULL) {
3020             _archive_allocator->clear_used();
3021           }
3022           for (uint i = 0; i < ParallelGCThreads; i++) {
3023             if (_evacuation_failed_info_array[i].has_failed()) {
3024               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3025             }
3026           }
3027         } else {
3028           // The "used" of the the collection set have already been subtracted
3029           // when they were freed.  Add in the bytes evacuated.
3030           increase_used(g1_policy()->bytes_copied_during_gc());
3031         }
3032 
3033         if (collector_state()->in_initial_mark_gc()) {
3034           // We have to do this before we notify the CM threads that
3035           // they can start working to make sure that all the
3036           // appropriate initialization is done on the CM object.
3037           concurrent_mark()->post_initial_mark();
3038           // Note that we don't actually trigger the CM thread at
3039           // this point. We do that later when we're sure that
3040           // the current thread has completed its logging output.
3041         }
3042 
3043         allocate_dummy_regions();
3044 
3045         _allocator->init_mutator_alloc_region();
3046 
3047         {
3048           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3049           if (expand_bytes > 0) {
3050             size_t bytes_before = capacity();
3051             // No need for an ergo logging here,
3052             // expansion_amount() does this when it returns a value > 0.
3053             double expand_ms;
3054             if (!expand(expand_bytes, _workers, &expand_ms)) {
3055               // We failed to expand the heap. Cannot do anything about it.
3056             }
3057             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3058           }
3059         }
3060 
3061         // We redo the verification but now wrt to the new CSet which
3062         // has just got initialized after the previous CSet was freed.
3063         _cm->verify_no_cset_oops();
3064 
3065         // This timing is only used by the ergonomics to handle our pause target.
3066         // It is unclear why this should not include the full pause. We will
3067         // investigate this in CR 7178365.
3068         double sample_end_time_sec = os::elapsedTime();
3069         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3070         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3071         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3072 
3073         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3074         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3075 
3076         if (VerifyRememberedSets) {
3077           log_info(gc, verify)("[Verifying RemSets after GC]");
3078           VerifyRegionRemSetClosure v_cl;
3079           heap_region_iterate(&v_cl);
3080         }
3081 
3082         _verifier->verify_after_gc(verify_type);
3083         _verifier->check_bitmaps("GC End");
3084 
3085         assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3086         _ref_processor_stw->verify_no_references_recorded();
3087 
3088         // CM reference discovery will be re-enabled if necessary.
3089       }
3090 
3091 #ifdef TRACESPINNING
3092       ParallelTaskTerminator::print_termination_counts();
3093 #endif
3094 
3095       gc_epilogue(false);
3096     }
3097 
3098     // Print the remainder of the GC log output.
3099     if (evacuation_failed()) {
3100       log_info(gc)("To-space exhausted");
3101     }
3102 
3103     g1_policy()->print_phases();
3104     heap_transition.print();
3105 
3106     // It is not yet to safe to tell the concurrent mark to
3107     // start as we have some optional output below. We don't want the
3108     // output from the concurrent mark thread interfering with this
3109     // logging output either.
3110 
3111     _hrm.verify_optional();
3112     _verifier->verify_region_sets_optional();
3113 
3114     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3115     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3116 
3117     print_heap_after_gc();
3118     print_heap_regions();
3119     trace_heap_after_gc(_gc_tracer_stw);
3120 
3121     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3122     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3123     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3124     // before any GC notifications are raised.
3125     g1mm()->update_sizes();
3126 
3127     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3128     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3129     _gc_timer_stw->register_gc_end();
3130     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3131   }
3132   // It should now be safe to tell the concurrent mark thread to start
3133   // without its logging output interfering with the logging output
3134   // that came from the pause.
3135 
3136   if (should_start_conc_mark) {
3137     // CAUTION: after the doConcurrentMark() call below,
3138     // the concurrent marking thread(s) could be running
3139     // concurrently with us. Make sure that anything after
3140     // this point does not assume that we are the only GC thread
3141     // running. Note: of course, the actual marking work will
3142     // not start until the safepoint itself is released in
3143     // SuspendibleThreadSet::desynchronize().
3144     do_concurrent_mark();
3145   }
3146 
3147   return true;
3148 }
3149 
3150 void G1CollectedHeap::remove_self_forwarding_pointers() {
3151   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3152   workers()->run_task(&rsfp_task);
3153 }
3154 
3155 void G1CollectedHeap::restore_after_evac_failure() {
3156   double remove_self_forwards_start = os::elapsedTime();
3157 
3158   remove_self_forwarding_pointers();
3159   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3160   _preserved_marks_set.restore(&task_executor);
3161 
3162   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3163 }
3164 
3165 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3166   if (!_evacuation_failed) {
3167     _evacuation_failed = true;
3168   }
3169 
3170   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3171   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3172 }
3173 
3174 bool G1ParEvacuateFollowersClosure::offer_termination() {
3175   EventGCPhaseParallel event;
3176   G1ParScanThreadState* const pss = par_scan_state();
3177   start_term_time();
3178   const bool res = terminator()->offer_termination();
3179   end_term_time();
3180   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3181   return res;
3182 }
3183 
3184 void G1ParEvacuateFollowersClosure::do_void() {
3185   EventGCPhaseParallel event;
3186   G1ParScanThreadState* const pss = par_scan_state();
3187   pss->trim_queue();
3188   event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3189   do {
3190     EventGCPhaseParallel event;
3191     pss->steal_and_trim_queue(queues());
3192     event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3193   } while (!offer_termination());
3194 }
3195 
3196 class G1ParTask : public AbstractGangTask {
3197 protected:
3198   G1CollectedHeap*         _g1h;
3199   G1ParScanThreadStateSet* _pss;
3200   RefToScanQueueSet*       _queues;
3201   G1RootProcessor*         _root_processor;
3202   ParallelTaskTerminator   _terminator;
3203   uint                     _n_workers;
3204 
3205 public:
3206   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3207     : AbstractGangTask("G1 collection"),
3208       _g1h(g1h),
3209       _pss(per_thread_states),
3210       _queues(task_queues),
3211       _root_processor(root_processor),
3212       _terminator(n_workers, _queues),
3213       _n_workers(n_workers)
3214   {}
3215 
3216   void work(uint worker_id) {
3217     if (worker_id >= _n_workers) return;  // no work needed this round
3218 
3219     double start_sec = os::elapsedTime();
3220     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3221 
3222     {
3223       ResourceMark rm;
3224       HandleMark   hm;
3225 
3226       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3227 
3228       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3229       pss->set_ref_discoverer(rp);
3230 
3231       double start_strong_roots_sec = os::elapsedTime();
3232 
3233       _root_processor->evacuate_roots(pss, worker_id);
3234 
3235       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3236       // treating the nmethods visited to act as roots for concurrent marking.
3237       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3238       // objects copied by the current evacuation.
3239       _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3240 
3241       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3242 
3243       double term_sec = 0.0;
3244       size_t evac_term_attempts = 0;
3245       {
3246         double start = os::elapsedTime();
3247         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3248         evac.do_void();
3249 
3250         evac_term_attempts = evac.term_attempts();
3251         term_sec = evac.term_time();
3252         double elapsed_sec = os::elapsedTime() - start;
3253 
3254         G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3255         p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3256         p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3257         p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3258       }
3259 
3260       assert(pss->queue_is_empty(), "should be empty");
3261 
3262       if (log_is_enabled(Debug, gc, task, stats)) {
3263         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3264         size_t lab_waste;
3265         size_t lab_undo_waste;
3266         pss->waste(lab_waste, lab_undo_waste);
3267         _g1h->print_termination_stats(worker_id,
3268                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3269                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3270                                       term_sec * 1000.0,                          /* evac term time */
3271                                       evac_term_attempts,                         /* evac term attempts */
3272                                       lab_waste,                                  /* alloc buffer waste */
3273                                       lab_undo_waste                              /* undo waste */
3274                                       );
3275       }
3276 
3277       // Close the inner scope so that the ResourceMark and HandleMark
3278       // destructors are executed here and are included as part of the
3279       // "GC Worker Time".
3280     }
3281     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3282   }
3283 };
3284 
3285 void G1CollectedHeap::print_termination_stats_hdr() {
3286   log_debug(gc, task, stats)("GC Termination Stats");
3287   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3288   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3289   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3290 }
3291 
3292 void G1CollectedHeap::print_termination_stats(uint worker_id,
3293                                               double elapsed_ms,
3294                                               double strong_roots_ms,
3295                                               double term_ms,
3296                                               size_t term_attempts,
3297                                               size_t alloc_buffer_waste,
3298                                               size_t undo_waste) const {
3299   log_debug(gc, task, stats)
3300               ("%3d %9.2f %9.2f %6.2f "
3301                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3302                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3303                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3304                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3305                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3306                alloc_buffer_waste * HeapWordSize / K,
3307                undo_waste * HeapWordSize / K);
3308 }
3309 
3310 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3311                                         bool class_unloading_occurred) {
3312   uint n_workers = workers()->active_workers();
3313 
3314   G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3315   ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred);
3316   workers()->run_task(&g1_unlink_task);
3317 }
3318 
3319 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3320                                        bool process_strings,
3321                                        bool process_string_dedup) {
3322   if (!process_strings && !process_string_dedup) {
3323     // Nothing to clean.
3324     return;
3325   }
3326 
3327   G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3328   StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings);
3329   workers()->run_task(&g1_unlink_task);
3330 }
3331 
3332 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3333  private:
3334   DirtyCardQueueSet* _queue;
3335   G1CollectedHeap* _g1h;
3336  public:
3337   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3338     _queue(queue), _g1h(g1h) { }
3339 
3340   virtual void work(uint worker_id) {
3341     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3342     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3343 
3344     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3345     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3346 
3347     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3348   }
3349 };
3350 
3351 void G1CollectedHeap::redirty_logged_cards() {
3352   double redirty_logged_cards_start = os::elapsedTime();
3353 
3354   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3355   dirty_card_queue_set().reset_for_par_iteration();
3356   workers()->run_task(&redirty_task);
3357 
3358   DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3359   dcq.merge_bufferlists(&dirty_card_queue_set());
3360   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3361 
3362   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3363 }
3364 
3365 // Weak Reference Processing support
3366 
3367 bool G1STWIsAliveClosure::do_object_b(oop p) {
3368   // An object is reachable if it is outside the collection set,
3369   // or is inside and copied.
3370   return !_g1h->is_in_cset(p) || p->is_forwarded();
3371 }
3372 
3373 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3374   assert(obj != NULL, "must not be NULL");
3375   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3376   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3377   // may falsely indicate that this is not the case here: however the collection set only
3378   // contains old regions when concurrent mark is not running.
3379   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3380 }
3381 
3382 // Non Copying Keep Alive closure
3383 class G1KeepAliveClosure: public OopClosure {
3384   G1CollectedHeap*_g1h;
3385 public:
3386   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3387   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3388   void do_oop(oop* p) {
3389     oop obj = *p;
3390     assert(obj != NULL, "the caller should have filtered out NULL values");
3391 
3392     const InCSetState cset_state =_g1h->in_cset_state(obj);
3393     if (!cset_state.is_in_cset_or_humongous()) {
3394       return;
3395     }
3396     if (cset_state.is_in_cset()) {
3397       assert( obj->is_forwarded(), "invariant" );
3398       *p = obj->forwardee();
3399     } else {
3400       assert(!obj->is_forwarded(), "invariant" );
3401       assert(cset_state.is_humongous(),
3402              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3403      _g1h->set_humongous_is_live(obj);
3404     }
3405   }
3406 };
3407 
3408 // Copying Keep Alive closure - can be called from both
3409 // serial and parallel code as long as different worker
3410 // threads utilize different G1ParScanThreadState instances
3411 // and different queues.
3412 
3413 class G1CopyingKeepAliveClosure: public OopClosure {
3414   G1CollectedHeap*         _g1h;
3415   G1ParScanThreadState*    _par_scan_state;
3416 
3417 public:
3418   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3419                             G1ParScanThreadState* pss):
3420     _g1h(g1h),
3421     _par_scan_state(pss)
3422   {}
3423 
3424   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3425   virtual void do_oop(      oop* p) { do_oop_work(p); }
3426 
3427   template <class T> void do_oop_work(T* p) {
3428     oop obj = RawAccess<>::oop_load(p);
3429 
3430     if (_g1h->is_in_cset_or_humongous(obj)) {
3431       // If the referent object has been forwarded (either copied
3432       // to a new location or to itself in the event of an
3433       // evacuation failure) then we need to update the reference
3434       // field and, if both reference and referent are in the G1
3435       // heap, update the RSet for the referent.
3436       //
3437       // If the referent has not been forwarded then we have to keep
3438       // it alive by policy. Therefore we have copy the referent.
3439       //
3440       // When the queue is drained (after each phase of reference processing)
3441       // the object and it's followers will be copied, the reference field set
3442       // to point to the new location, and the RSet updated.
3443       _par_scan_state->push_on_queue(p);
3444     }
3445   }
3446 };
3447 
3448 // Serial drain queue closure. Called as the 'complete_gc'
3449 // closure for each discovered list in some of the
3450 // reference processing phases.
3451 
3452 class G1STWDrainQueueClosure: public VoidClosure {
3453 protected:
3454   G1CollectedHeap* _g1h;
3455   G1ParScanThreadState* _par_scan_state;
3456 
3457   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3458 
3459 public:
3460   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3461     _g1h(g1h),
3462     _par_scan_state(pss)
3463   { }
3464 
3465   void do_void() {
3466     G1ParScanThreadState* const pss = par_scan_state();
3467     pss->trim_queue();
3468   }
3469 };
3470 
3471 // Parallel Reference Processing closures
3472 
3473 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3474 // processing during G1 evacuation pauses.
3475 
3476 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3477 private:
3478   G1CollectedHeap*          _g1h;
3479   G1ParScanThreadStateSet*  _pss;
3480   RefToScanQueueSet*        _queues;
3481   WorkGang*                 _workers;
3482 
3483 public:
3484   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3485                            G1ParScanThreadStateSet* per_thread_states,
3486                            WorkGang* workers,
3487                            RefToScanQueueSet *task_queues) :
3488     _g1h(g1h),
3489     _pss(per_thread_states),
3490     _queues(task_queues),
3491     _workers(workers)
3492   {
3493     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3494   }
3495 
3496   // Executes the given task using concurrent marking worker threads.
3497   virtual void execute(ProcessTask& task, uint ergo_workers);
3498 };
3499 
3500 // Gang task for possibly parallel reference processing
3501 
3502 class G1STWRefProcTaskProxy: public AbstractGangTask {
3503   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3504   ProcessTask&     _proc_task;
3505   G1CollectedHeap* _g1h;
3506   G1ParScanThreadStateSet* _pss;
3507   RefToScanQueueSet* _task_queues;
3508   ParallelTaskTerminator* _terminator;
3509 
3510 public:
3511   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3512                         G1CollectedHeap* g1h,
3513                         G1ParScanThreadStateSet* per_thread_states,
3514                         RefToScanQueueSet *task_queues,
3515                         ParallelTaskTerminator* terminator) :
3516     AbstractGangTask("Process reference objects in parallel"),
3517     _proc_task(proc_task),
3518     _g1h(g1h),
3519     _pss(per_thread_states),
3520     _task_queues(task_queues),
3521     _terminator(terminator)
3522   {}
3523 
3524   virtual void work(uint worker_id) {
3525     // The reference processing task executed by a single worker.
3526     ResourceMark rm;
3527     HandleMark   hm;
3528 
3529     G1STWIsAliveClosure is_alive(_g1h);
3530 
3531     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3532     pss->set_ref_discoverer(NULL);
3533 
3534     // Keep alive closure.
3535     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3536 
3537     // Complete GC closure
3538     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3539 
3540     // Call the reference processing task's work routine.
3541     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3542 
3543     // Note we cannot assert that the refs array is empty here as not all
3544     // of the processing tasks (specifically phase2 - pp2_work) execute
3545     // the complete_gc closure (which ordinarily would drain the queue) so
3546     // the queue may not be empty.
3547   }
3548 };
3549 
3550 // Driver routine for parallel reference processing.
3551 // Creates an instance of the ref processing gang
3552 // task and has the worker threads execute it.
3553 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3554   assert(_workers != NULL, "Need parallel worker threads.");
3555 
3556   assert(_workers->active_workers() >= ergo_workers,
3557          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3558          ergo_workers, _workers->active_workers());
3559   ParallelTaskTerminator terminator(ergo_workers, _queues);
3560   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3561 
3562   _workers->run_task(&proc_task_proxy, ergo_workers);
3563 }
3564 
3565 // End of weak reference support closures
3566 
3567 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3568   double ref_proc_start = os::elapsedTime();
3569 
3570   ReferenceProcessor* rp = _ref_processor_stw;
3571   assert(rp->discovery_enabled(), "should have been enabled");
3572 
3573   // Closure to test whether a referent is alive.
3574   G1STWIsAliveClosure is_alive(this);
3575 
3576   // Even when parallel reference processing is enabled, the processing
3577   // of JNI refs is serial and performed serially by the current thread
3578   // rather than by a worker. The following PSS will be used for processing
3579   // JNI refs.
3580 
3581   // Use only a single queue for this PSS.
3582   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3583   pss->set_ref_discoverer(NULL);
3584   assert(pss->queue_is_empty(), "pre-condition");
3585 
3586   // Keep alive closure.
3587   G1CopyingKeepAliveClosure keep_alive(this, pss);
3588 
3589   // Serial Complete GC closure
3590   G1STWDrainQueueClosure drain_queue(this, pss);
3591 
3592   // Setup the soft refs policy...
3593   rp->setup_policy(false);
3594 
3595   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3596 
3597   ReferenceProcessorStats stats;
3598   if (!rp->processing_is_mt()) {
3599     // Serial reference processing...
3600     stats = rp->process_discovered_references(&is_alive,
3601                                               &keep_alive,
3602                                               &drain_queue,
3603                                               NULL,
3604                                               pt);
3605   } else {
3606     uint no_of_gc_workers = workers()->active_workers();
3607 
3608     // Parallel reference processing
3609     assert(no_of_gc_workers <= rp->max_num_queues(),
3610            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3611            no_of_gc_workers,  rp->max_num_queues());
3612 
3613     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3614     stats = rp->process_discovered_references(&is_alive,
3615                                               &keep_alive,
3616                                               &drain_queue,
3617                                               &par_task_executor,
3618                                               pt);
3619   }
3620 
3621   _gc_tracer_stw->report_gc_reference_stats(stats);
3622 
3623   // We have completed copying any necessary live referent objects.
3624   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3625 
3626   make_pending_list_reachable();
3627 
3628   rp->verify_no_references_recorded();
3629 
3630   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3631   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3632 }
3633 
3634 void G1CollectedHeap::make_pending_list_reachable() {
3635   if (collector_state()->in_initial_mark_gc()) {
3636     oop pll_head = Universe::reference_pending_list();
3637     if (pll_head != NULL) {
3638       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3639       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3640     }
3641   }
3642 }
3643 
3644 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3645   double merge_pss_time_start = os::elapsedTime();
3646   per_thread_states->flush();
3647   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3648 }
3649 
3650 void G1CollectedHeap::pre_evacuate_collection_set() {
3651   _expand_heap_after_alloc_failure = true;
3652   _evacuation_failed = false;
3653 
3654   // Disable the hot card cache.
3655   _hot_card_cache->reset_hot_cache_claimed_index();
3656   _hot_card_cache->set_use_cache(false);
3657 
3658   g1_rem_set()->prepare_for_oops_into_collection_set_do();
3659   _preserved_marks_set.assert_empty();
3660 
3661   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3662 
3663   // InitialMark needs claim bits to keep track of the marked-through CLDs.
3664   if (collector_state()->in_initial_mark_gc()) {
3665     double start_clear_claimed_marks = os::elapsedTime();
3666 
3667     ClassLoaderDataGraph::clear_claimed_marks();
3668 
3669     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3670     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3671   }
3672 }
3673 
3674 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3675   // Should G1EvacuationFailureALot be in effect for this GC?
3676   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3677 
3678   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3679 
3680   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3681 
3682   double start_par_time_sec = os::elapsedTime();
3683   double end_par_time_sec;
3684 
3685   {
3686     const uint n_workers = workers()->active_workers();
3687     G1RootProcessor root_processor(this, n_workers);
3688     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3689 
3690     print_termination_stats_hdr();
3691 
3692     workers()->run_task(&g1_par_task);
3693     end_par_time_sec = os::elapsedTime();
3694 
3695     // Closing the inner scope will execute the destructor
3696     // for the G1RootProcessor object. We record the current
3697     // elapsed time before closing the scope so that time
3698     // taken for the destructor is NOT included in the
3699     // reported parallel time.
3700   }
3701 
3702   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3703   phase_times->record_par_time(par_time_ms);
3704 
3705   double code_root_fixup_time_ms =
3706         (os::elapsedTime() - end_par_time_sec) * 1000.0;
3707   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
3708 }
3709 
3710 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3711   // Also cleans the card table from temporary duplicate detection information used
3712   // during UpdateRS/ScanRS.
3713   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
3714 
3715   // Process any discovered reference objects - we have
3716   // to do this _before_ we retire the GC alloc regions
3717   // as we may have to copy some 'reachable' referent
3718   // objects (and their reachable sub-graphs) that were
3719   // not copied during the pause.
3720   process_discovered_references(per_thread_states);
3721 
3722   // FIXME
3723   // CM's reference processing also cleans up the string table.
3724   // Should we do that here also? We could, but it is a serial operation
3725   // and could significantly increase the pause time.
3726 
3727   G1STWIsAliveClosure is_alive(this);
3728   G1KeepAliveClosure keep_alive(this);
3729 
3730   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3731                               g1_policy()->phase_times()->weak_phase_times());
3732 
3733   if (G1StringDedup::is_enabled()) {
3734     double fixup_start = os::elapsedTime();
3735 
3736     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
3737 
3738     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
3739     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
3740   }
3741 
3742   if (evacuation_failed()) {
3743     restore_after_evac_failure();
3744 
3745     // Reset the G1EvacuationFailureALot counters and flags
3746     // Note: the values are reset only when an actual
3747     // evacuation failure occurs.
3748     NOT_PRODUCT(reset_evacuation_should_fail();)
3749   }
3750 
3751   _preserved_marks_set.assert_empty();
3752 
3753   _allocator->release_gc_alloc_regions(evacuation_info);
3754 
3755   merge_per_thread_state_info(per_thread_states);
3756 
3757   // Reset and re-enable the hot card cache.
3758   // Note the counts for the cards in the regions in the
3759   // collection set are reset when the collection set is freed.
3760   _hot_card_cache->reset_hot_cache();
3761   _hot_card_cache->set_use_cache(true);
3762 
3763   purge_code_root_memory();
3764 
3765   redirty_logged_cards();
3766 #if COMPILER2_OR_JVMCI
3767   double start = os::elapsedTime();
3768   DerivedPointerTable::update_pointers();
3769   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3770 #endif
3771   g1_policy()->print_age_table();
3772 }
3773 
3774 void G1CollectedHeap::record_obj_copy_mem_stats() {
3775   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3776 
3777   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3778                                                create_g1_evac_summary(&_old_evac_stats));
3779 }
3780 
3781 void G1CollectedHeap::free_region(HeapRegion* hr,
3782                                   FreeRegionList* free_list,
3783                                   bool skip_remset,
3784                                   bool skip_hot_card_cache,
3785                                   bool locked) {
3786   assert(!hr->is_free(), "the region should not be free");
3787   assert(!hr->is_empty(), "the region should not be empty");
3788   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
3789   assert(free_list != NULL, "pre-condition");
3790 
3791   if (G1VerifyBitmaps) {
3792     MemRegion mr(hr->bottom(), hr->end());
3793     concurrent_mark()->clear_range_in_prev_bitmap(mr);
3794   }
3795 
3796   // Clear the card counts for this region.
3797   // Note: we only need to do this if the region is not young
3798   // (since we don't refine cards in young regions).
3799   if (!skip_hot_card_cache && !hr->is_young()) {
3800     _hot_card_cache->reset_card_counts(hr);
3801   }
3802   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3803   _g1_policy->remset_tracker()->update_at_free(hr);
3804   free_list->add_ordered(hr);
3805 }
3806 
3807 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3808                                             FreeRegionList* free_list) {
3809   assert(hr->is_humongous(), "this is only for humongous regions");
3810   assert(free_list != NULL, "pre-condition");
3811   hr->clear_humongous();
3812   free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3813 }
3814 
3815 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3816                                            const uint humongous_regions_removed) {
3817   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3818     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3819     _old_set.bulk_remove(old_regions_removed);
3820     _humongous_set.bulk_remove(humongous_regions_removed);
3821   }
3822 
3823 }
3824 
3825 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3826   assert(list != NULL, "list can't be null");
3827   if (!list->is_empty()) {
3828     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3829     _hrm.insert_list_into_free_list(list);
3830   }
3831 }
3832 
3833 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3834   decrease_used(bytes);
3835 }
3836 
3837 class G1FreeCollectionSetTask : public AbstractGangTask {
3838 private:
3839 
3840   // Closure applied to all regions in the collection set to do work that needs to
3841   // be done serially in a single thread.
3842   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3843   private:
3844     EvacuationInfo* _evacuation_info;
3845     const size_t* _surviving_young_words;
3846 
3847     // Bytes used in successfully evacuated regions before the evacuation.
3848     size_t _before_used_bytes;
3849     // Bytes used in unsucessfully evacuated regions before the evacuation
3850     size_t _after_used_bytes;
3851 
3852     size_t _bytes_allocated_in_old_since_last_gc;
3853 
3854     size_t _failure_used_words;
3855     size_t _failure_waste_words;
3856 
3857     FreeRegionList _local_free_list;
3858   public:
3859     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3860       HeapRegionClosure(),
3861       _evacuation_info(evacuation_info),
3862       _surviving_young_words(surviving_young_words),
3863       _before_used_bytes(0),
3864       _after_used_bytes(0),
3865       _bytes_allocated_in_old_since_last_gc(0),
3866       _failure_used_words(0),
3867       _failure_waste_words(0),
3868       _local_free_list("Local Region List for CSet Freeing") {
3869     }
3870 
3871     virtual bool do_heap_region(HeapRegion* r) {
3872       G1CollectedHeap* g1h = G1CollectedHeap::heap();
3873 
3874       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3875       g1h->clear_in_cset(r);
3876 
3877       if (r->is_young()) {
3878         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
3879                "Young index %d is wrong for region %u of type %s with %u young regions",
3880                r->young_index_in_cset(),
3881                r->hrm_index(),
3882                r->get_type_str(),
3883                g1h->collection_set()->young_region_length());
3884         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
3885         r->record_surv_words_in_group(words_survived);
3886       }
3887 
3888       if (!r->evacuation_failed()) {
3889         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
3890         _before_used_bytes += r->used();
3891         g1h->free_region(r,
3892                          &_local_free_list,
3893                          true, /* skip_remset */
3894                          true, /* skip_hot_card_cache */
3895                          true  /* locked */);
3896       } else {
3897         r->uninstall_surv_rate_group();
3898         r->set_young_index_in_cset(-1);
3899         r->set_evacuation_failed(false);
3900         // When moving a young gen region to old gen, we "allocate" that whole region
3901         // there. This is in addition to any already evacuated objects. Notify the
3902         // policy about that.
3903         // Old gen regions do not cause an additional allocation: both the objects
3904         // still in the region and the ones already moved are accounted for elsewhere.
3905         if (r->is_young()) {
3906           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
3907         }
3908         // The region is now considered to be old.
3909         r->set_old();
3910         // Do some allocation statistics accounting. Regions that failed evacuation
3911         // are always made old, so there is no need to update anything in the young
3912         // gen statistics, but we need to update old gen statistics.
3913         size_t used_words = r->marked_bytes() / HeapWordSize;
3914 
3915         _failure_used_words += used_words;
3916         _failure_waste_words += HeapRegion::GrainWords - used_words;
3917 
3918         g1h->old_set_add(r);
3919         _after_used_bytes += r->used();
3920       }
3921       return false;
3922     }
3923 
3924     void complete_work() {
3925       G1CollectedHeap* g1h = G1CollectedHeap::heap();
3926 
3927       _evacuation_info->set_regions_freed(_local_free_list.length());
3928       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
3929 
3930       g1h->prepend_to_freelist(&_local_free_list);
3931       g1h->decrement_summary_bytes(_before_used_bytes);
3932 
3933       G1Policy* policy = g1h->g1_policy();
3934       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
3935 
3936       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
3937     }
3938   };
3939 
3940   G1CollectionSet* _collection_set;
3941   G1SerialFreeCollectionSetClosure _cl;
3942   const size_t* _surviving_young_words;
3943 
3944   size_t _rs_lengths;
3945 
3946   volatile jint _serial_work_claim;
3947 
3948   struct WorkItem {
3949     uint region_idx;
3950     bool is_young;
3951     bool evacuation_failed;
3952 
3953     WorkItem(HeapRegion* r) {
3954       region_idx = r->hrm_index();
3955       is_young = r->is_young();
3956       evacuation_failed = r->evacuation_failed();
3957     }
3958   };
3959 
3960   volatile size_t _parallel_work_claim;
3961   size_t _num_work_items;
3962   WorkItem* _work_items;
3963 
3964   void do_serial_work() {
3965     // Need to grab the lock to be allowed to modify the old region list.
3966     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3967     _collection_set->iterate(&_cl);
3968   }
3969 
3970   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
3971     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3972 
3973     HeapRegion* r = g1h->region_at(region_idx);
3974     assert(!g1h->is_on_master_free_list(r), "sanity");
3975 
3976     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
3977 
3978     if (!is_young) {
3979       g1h->_hot_card_cache->reset_card_counts(r);
3980     }
3981 
3982     if (!evacuation_failed) {
3983       r->rem_set()->clear_locked();
3984     }
3985   }
3986 
3987   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
3988   private:
3989     size_t _cur_idx;
3990     WorkItem* _work_items;
3991   public:
3992     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
3993 
3994     virtual bool do_heap_region(HeapRegion* r) {
3995       _work_items[_cur_idx++] = WorkItem(r);
3996       return false;
3997     }
3998   };
3999 
4000   void prepare_work() {
4001     G1PrepareFreeCollectionSetClosure cl(_work_items);
4002     _collection_set->iterate(&cl);
4003   }
4004 
4005   void complete_work() {
4006     _cl.complete_work();
4007 
4008     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4009     policy->record_max_rs_lengths(_rs_lengths);
4010     policy->cset_regions_freed();
4011   }
4012 public:
4013   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4014     AbstractGangTask("G1 Free Collection Set"),
4015     _collection_set(collection_set),
4016     _cl(evacuation_info, surviving_young_words),
4017     _surviving_young_words(surviving_young_words),
4018     _rs_lengths(0),
4019     _serial_work_claim(0),
4020     _parallel_work_claim(0),
4021     _num_work_items(collection_set->region_length()),
4022     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4023     prepare_work();
4024   }
4025 
4026   ~G1FreeCollectionSetTask() {
4027     complete_work();
4028     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4029   }
4030 
4031   // Chunk size for work distribution. The chosen value has been determined experimentally
4032   // to be a good tradeoff between overhead and achievable parallelism.
4033   static uint chunk_size() { return 32; }
4034 
4035   virtual void work(uint worker_id) {
4036     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4037 
4038     // Claim serial work.
4039     if (_serial_work_claim == 0) {
4040       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4041       if (value == 0) {
4042         double serial_time = os::elapsedTime();
4043         do_serial_work();
4044         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4045       }
4046     }
4047 
4048     // Start parallel work.
4049     double young_time = 0.0;
4050     bool has_young_time = false;
4051     double non_young_time = 0.0;
4052     bool has_non_young_time = false;
4053 
4054     while (true) {
4055       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4056       size_t cur = end - chunk_size();
4057 
4058       if (cur >= _num_work_items) {
4059         break;
4060       }
4061 
4062       EventGCPhaseParallel event;
4063       double start_time = os::elapsedTime();
4064 
4065       end = MIN2(end, _num_work_items);
4066 
4067       for (; cur < end; cur++) {
4068         bool is_young = _work_items[cur].is_young;
4069 
4070         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4071 
4072         double end_time = os::elapsedTime();
4073         double time_taken = end_time - start_time;
4074         if (is_young) {
4075           young_time += time_taken;
4076           has_young_time = true;
4077           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4078         } else {
4079           non_young_time += time_taken;
4080           has_non_young_time = true;
4081           event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4082         }
4083         start_time = end_time;
4084       }
4085     }
4086 
4087     if (has_young_time) {
4088       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4089     }
4090     if (has_non_young_time) {
4091       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4092     }
4093   }
4094 };
4095 
4096 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4097   _eden.clear();
4098 
4099   double free_cset_start_time = os::elapsedTime();
4100 
4101   {
4102     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4103     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4104 
4105     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4106 
4107     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4108                         cl.name(),
4109                         num_workers,
4110                         _collection_set.region_length());
4111     workers()->run_task(&cl, num_workers);
4112   }
4113   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4114 
4115   collection_set->clear();
4116 }
4117 
4118 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4119  private:
4120   FreeRegionList* _free_region_list;
4121   HeapRegionSet* _proxy_set;
4122   uint _humongous_objects_reclaimed;
4123   uint _humongous_regions_reclaimed;
4124   size_t _freed_bytes;
4125  public:
4126 
4127   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4128     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4129   }
4130 
4131   virtual bool do_heap_region(HeapRegion* r) {
4132     if (!r->is_starts_humongous()) {
4133       return false;
4134     }
4135 
4136     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4137 
4138     oop obj = (oop)r->bottom();
4139     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4140 
4141     // The following checks whether the humongous object is live are sufficient.
4142     // The main additional check (in addition to having a reference from the roots
4143     // or the young gen) is whether the humongous object has a remembered set entry.
4144     //
4145     // A humongous object cannot be live if there is no remembered set for it
4146     // because:
4147     // - there can be no references from within humongous starts regions referencing
4148     // the object because we never allocate other objects into them.
4149     // (I.e. there are no intra-region references that may be missed by the
4150     // remembered set)
4151     // - as soon there is a remembered set entry to the humongous starts region
4152     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4153     // until the end of a concurrent mark.
4154     //
4155     // It is not required to check whether the object has been found dead by marking
4156     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4157     // all objects allocated during that time are considered live.
4158     // SATB marking is even more conservative than the remembered set.
4159     // So if at this point in the collection there is no remembered set entry,
4160     // nobody has a reference to it.
4161     // At the start of collection we flush all refinement logs, and remembered sets
4162     // are completely up-to-date wrt to references to the humongous object.
4163     //
4164     // Other implementation considerations:
4165     // - never consider object arrays at this time because they would pose
4166     // considerable effort for cleaning up the the remembered sets. This is
4167     // required because stale remembered sets might reference locations that
4168     // are currently allocated into.
4169     uint region_idx = r->hrm_index();
4170     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4171         !r->rem_set()->is_empty()) {
4172       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",
4173                                region_idx,
4174                                (size_t)obj->size() * HeapWordSize,
4175                                p2i(r->bottom()),
4176                                r->rem_set()->occupied(),
4177                                r->rem_set()->strong_code_roots_list_length(),
4178                                next_bitmap->is_marked(r->bottom()),
4179                                g1h->is_humongous_reclaim_candidate(region_idx),
4180                                obj->is_typeArray()
4181                               );
4182       return false;
4183     }
4184 
4185     guarantee(obj->is_typeArray(),
4186               "Only eagerly reclaiming type arrays is supported, but the object "
4187               PTR_FORMAT " is not.", p2i(r->bottom()));
4188 
4189     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",
4190                              region_idx,
4191                              (size_t)obj->size() * HeapWordSize,
4192                              p2i(r->bottom()),
4193                              r->rem_set()->occupied(),
4194                              r->rem_set()->strong_code_roots_list_length(),
4195                              next_bitmap->is_marked(r->bottom()),
4196                              g1h->is_humongous_reclaim_candidate(region_idx),
4197                              obj->is_typeArray()
4198                             );
4199 
4200     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4201     cm->humongous_object_eagerly_reclaimed(r);
4202     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4203            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4204            region_idx,
4205            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4206            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4207     _humongous_objects_reclaimed++;
4208     do {
4209       HeapRegion* next = g1h->next_region_in_humongous(r);
4210       _freed_bytes += r->used();
4211       r->set_containing_set(NULL);
4212       _humongous_regions_reclaimed++;
4213       g1h->free_humongous_region(r, _free_region_list);
4214       r = next;
4215     } while (r != NULL);
4216 
4217     return false;
4218   }
4219 
4220   uint humongous_objects_reclaimed() {
4221     return _humongous_objects_reclaimed;
4222   }
4223 
4224   uint humongous_regions_reclaimed() {
4225     return _humongous_regions_reclaimed;
4226   }
4227 
4228   size_t bytes_freed() const {
4229     return _freed_bytes;
4230   }
4231 };
4232 
4233 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4234   assert_at_safepoint_on_vm_thread();
4235 
4236   if (!G1EagerReclaimHumongousObjects ||
4237       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4238     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4239     return;
4240   }
4241 
4242   double start_time = os::elapsedTime();
4243 
4244   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4245 
4246   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4247   heap_region_iterate(&cl);
4248 
4249   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4250 
4251   G1HRPrinter* hrp = hr_printer();
4252   if (hrp->is_active()) {
4253     FreeRegionListIterator iter(&local_cleanup_list);
4254     while (iter.more_available()) {
4255       HeapRegion* hr = iter.get_next();
4256       hrp->cleanup(hr);
4257     }
4258   }
4259 
4260   prepend_to_freelist(&local_cleanup_list);
4261   decrement_summary_bytes(cl.bytes_freed());
4262 
4263   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4264                                                                     cl.humongous_objects_reclaimed());
4265 }
4266 
4267 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4268 public:
4269   virtual bool do_heap_region(HeapRegion* r) {
4270     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4271     G1CollectedHeap::heap()->clear_in_cset(r);
4272     r->set_young_index_in_cset(-1);
4273     return false;
4274   }
4275 };
4276 
4277 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4278   G1AbandonCollectionSetClosure cl;
4279   collection_set->iterate(&cl);
4280 
4281   collection_set->clear();
4282   collection_set->stop_incremental_building();
4283 }
4284 
4285 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4286   return _allocator->is_retained_old_region(hr);
4287 }
4288 
4289 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4290   _eden.add(hr);
4291   _g1_policy->set_region_eden(hr);
4292 }
4293 
4294 #ifdef ASSERT
4295 
4296 class NoYoungRegionsClosure: public HeapRegionClosure {
4297 private:
4298   bool _success;
4299 public:
4300   NoYoungRegionsClosure() : _success(true) { }
4301   bool do_heap_region(HeapRegion* r) {
4302     if (r->is_young()) {
4303       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4304                             p2i(r->bottom()), p2i(r->end()));
4305       _success = false;
4306     }
4307     return false;
4308   }
4309   bool success() { return _success; }
4310 };
4311 
4312 bool G1CollectedHeap::check_young_list_empty() {
4313   bool ret = (young_regions_count() == 0);
4314 
4315   NoYoungRegionsClosure closure;
4316   heap_region_iterate(&closure);
4317   ret = ret && closure.success();
4318 
4319   return ret;
4320 }
4321 
4322 #endif // ASSERT
4323 
4324 class TearDownRegionSetsClosure : public HeapRegionClosure {
4325   HeapRegionSet *_old_set;
4326 
4327 public:
4328   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4329 
4330   bool do_heap_region(HeapRegion* r) {
4331     if (r->is_old()) {
4332       _old_set->remove(r);
4333     } else if(r->is_young()) {
4334       r->uninstall_surv_rate_group();
4335     } else {
4336       // We ignore free regions, we'll empty the free list afterwards.
4337       // We ignore humongous and archive regions, we're not tearing down these
4338       // sets.
4339       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4340              "it cannot be another type");
4341     }
4342     return false;
4343   }
4344 
4345   ~TearDownRegionSetsClosure() {
4346     assert(_old_set->is_empty(), "post-condition");
4347   }
4348 };
4349 
4350 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4351   assert_at_safepoint_on_vm_thread();
4352 
4353   if (!free_list_only) {
4354     TearDownRegionSetsClosure cl(&_old_set);
4355     heap_region_iterate(&cl);
4356 
4357     // Note that emptying the _young_list is postponed and instead done as
4358     // the first step when rebuilding the regions sets again. The reason for
4359     // this is that during a full GC string deduplication needs to know if
4360     // a collected region was young or old when the full GC was initiated.
4361   }
4362   _hrm.remove_all_free_regions();
4363 }
4364 
4365 void G1CollectedHeap::increase_used(size_t bytes) {
4366   _summary_bytes_used += bytes;
4367 }
4368 
4369 void G1CollectedHeap::decrease_used(size_t bytes) {
4370   assert(_summary_bytes_used >= bytes,
4371          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4372          _summary_bytes_used, bytes);
4373   _summary_bytes_used -= bytes;
4374 }
4375 
4376 void G1CollectedHeap::set_used(size_t bytes) {
4377   _summary_bytes_used = bytes;
4378 }
4379 
4380 class RebuildRegionSetsClosure : public HeapRegionClosure {
4381 private:
4382   bool _free_list_only;
4383 
4384   HeapRegionSet* _old_set;
4385   HeapRegionManager* _hrm;
4386 
4387   size_t _total_used;
4388 
4389 public:
4390   RebuildRegionSetsClosure(bool free_list_only,
4391                            HeapRegionSet* old_set,
4392                            HeapRegionManager* hrm) :
4393     _free_list_only(free_list_only),
4394     _old_set(old_set), _hrm(hrm), _total_used(0) {
4395     assert(_hrm->num_free_regions() == 0, "pre-condition");
4396     if (!free_list_only) {
4397       assert(_old_set->is_empty(), "pre-condition");
4398     }
4399   }
4400 
4401   bool do_heap_region(HeapRegion* r) {
4402     if (r->is_empty()) {
4403       assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4404       // Add free regions to the free list
4405       r->set_free();
4406       _hrm->insert_into_free_list(r);
4407     } else if (!_free_list_only) {
4408       assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4409 
4410       if (r->is_archive() || r->is_humongous()) {
4411         // We ignore archive and humongous regions. We left these sets unchanged.
4412       } else {
4413         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4414         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4415         r->move_to_old();
4416         _old_set->add(r);
4417       }
4418       _total_used += r->used();
4419     }
4420 
4421     return false;
4422   }
4423 
4424   size_t total_used() {
4425     return _total_used;
4426   }
4427 };
4428 
4429 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4430   assert_at_safepoint_on_vm_thread();
4431 
4432   if (!free_list_only) {
4433     _eden.clear();
4434     _survivor.clear();
4435   }
4436 
4437   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4438   heap_region_iterate(&cl);
4439 
4440   if (!free_list_only) {
4441     set_used(cl.total_used());
4442     if (_archive_allocator != NULL) {
4443       _archive_allocator->clear_used();
4444     }
4445   }
4446   assert(used() == recalculate_used(),
4447          "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4448          used(), recalculate_used());
4449 }
4450 
4451 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4452   HeapRegion* hr = heap_region_containing(p);
4453   return hr->is_in(p);
4454 }
4455 
4456 // Methods for the mutator alloc region
4457 
4458 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4459                                                       bool force) {
4460   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4461   bool should_allocate = g1_policy()->should_allocate_mutator_region();
4462   if (force || should_allocate) {
4463     HeapRegion* new_alloc_region = new_region(word_size,
4464                                               false /* is_old */,
4465                                               false /* do_expand */);
4466     if (new_alloc_region != NULL) {
4467       set_region_short_lived_locked(new_alloc_region);
4468       _hr_printer.alloc(new_alloc_region, !should_allocate);
4469       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4470       _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4471       return new_alloc_region;
4472     }
4473   }
4474   return NULL;
4475 }
4476 
4477 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4478                                                   size_t allocated_bytes) {
4479   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4480   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4481 
4482   collection_set()->add_eden_region(alloc_region);
4483   increase_used(allocated_bytes);
4484   _hr_printer.retire(alloc_region);
4485   // We update the eden sizes here, when the region is retired,
4486   // instead of when it's allocated, since this is the point that its
4487   // used space has been recorded in _summary_bytes_used.
4488   g1mm()->update_eden_size();
4489 }
4490 
4491 // Methods for the GC alloc regions
4492 
4493 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4494   if (dest.is_old()) {
4495     return true;
4496   } else {
4497     return survivor_regions_count() < g1_policy()->max_survivor_regions();
4498   }
4499 }
4500 
4501 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4502   assert(FreeList_lock->owned_by_self(), "pre-condition");
4503 
4504   if (!has_more_regions(dest)) {
4505     return NULL;
4506   }
4507 
4508   const bool is_survivor = dest.is_young();
4509 
4510   HeapRegion* new_alloc_region = new_region(word_size,
4511                                             !is_survivor,
4512                                             true /* do_expand */);
4513   if (new_alloc_region != NULL) {
4514     if (is_survivor) {
4515       new_alloc_region->set_survivor();
4516       _survivor.add(new_alloc_region);
4517       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4518     } else {
4519       new_alloc_region->set_old();
4520       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4521     }
4522     _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4523     _hr_printer.alloc(new_alloc_region);
4524     bool during_im = collector_state()->in_initial_mark_gc();
4525     new_alloc_region->note_start_of_copying(during_im);
4526     return new_alloc_region;
4527   }
4528   return NULL;
4529 }
4530 
4531 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4532                                              size_t allocated_bytes,
4533                                              InCSetState dest) {
4534   bool during_im = collector_state()->in_initial_mark_gc();
4535   alloc_region->note_end_of_copying(during_im);
4536   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4537   if (dest.is_old()) {
4538     old_set_add(alloc_region);
4539   }
4540   _hr_printer.retire(alloc_region);
4541 }
4542 
4543 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4544   bool expanded = false;
4545   uint index = _hrm.find_highest_free(&expanded);
4546 
4547   if (index != G1_NO_HRM_INDEX) {
4548     if (expanded) {
4549       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4550                                 HeapRegion::GrainWords * HeapWordSize);
4551     }
4552     _hrm.allocate_free_regions_starting_at(index, 1);
4553     return region_at(index);
4554   }
4555   return NULL;
4556 }
4557 
4558 // Optimized nmethod scanning
4559 
4560 class RegisterNMethodOopClosure: public OopClosure {
4561   G1CollectedHeap* _g1h;
4562   nmethod* _nm;
4563 
4564   template <class T> void do_oop_work(T* p) {
4565     T heap_oop = RawAccess<>::oop_load(p);
4566     if (!CompressedOops::is_null(heap_oop)) {
4567       oop obj = CompressedOops::decode_not_null(heap_oop);
4568       HeapRegion* hr = _g1h->heap_region_containing(obj);
4569       assert(!hr->is_continues_humongous(),
4570              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4571              " starting at " HR_FORMAT,
4572              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4573 
4574       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4575       hr->add_strong_code_root_locked(_nm);
4576     }
4577   }
4578 
4579 public:
4580   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4581     _g1h(g1h), _nm(nm) {}
4582 
4583   void do_oop(oop* p)       { do_oop_work(p); }
4584   void do_oop(narrowOop* p) { do_oop_work(p); }
4585 };
4586 
4587 class UnregisterNMethodOopClosure: public OopClosure {
4588   G1CollectedHeap* _g1h;
4589   nmethod* _nm;
4590 
4591   template <class T> void do_oop_work(T* p) {
4592     T heap_oop = RawAccess<>::oop_load(p);
4593     if (!CompressedOops::is_null(heap_oop)) {
4594       oop obj = CompressedOops::decode_not_null(heap_oop);
4595       HeapRegion* hr = _g1h->heap_region_containing(obj);
4596       assert(!hr->is_continues_humongous(),
4597              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4598              " starting at " HR_FORMAT,
4599              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4600 
4601       hr->remove_strong_code_root(_nm);
4602     }
4603   }
4604 
4605 public:
4606   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4607     _g1h(g1h), _nm(nm) {}
4608 
4609   void do_oop(oop* p)       { do_oop_work(p); }
4610   void do_oop(narrowOop* p) { do_oop_work(p); }
4611 };
4612 
4613 // Returns true if the reference points to an object that
4614 // can move in an incremental collection.
4615 bool G1CollectedHeap::is_scavengable(oop obj) {
4616   HeapRegion* hr = heap_region_containing(obj);
4617   return !hr->is_pinned();
4618 }
4619 
4620 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4621   guarantee(nm != NULL, "sanity");
4622   RegisterNMethodOopClosure reg_cl(this, nm);
4623   nm->oops_do(&reg_cl);
4624 }
4625 
4626 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4627   guarantee(nm != NULL, "sanity");
4628   UnregisterNMethodOopClosure reg_cl(this, nm);
4629   nm->oops_do(&reg_cl, true);
4630 }
4631 
4632 void G1CollectedHeap::purge_code_root_memory() {
4633   double purge_start = os::elapsedTime();
4634   G1CodeRootSet::purge();
4635   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4636   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4637 }
4638 
4639 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4640   G1CollectedHeap* _g1h;
4641 
4642 public:
4643   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4644     _g1h(g1h) {}
4645 
4646   void do_code_blob(CodeBlob* cb) {
4647     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4648     if (nm == NULL) {
4649       return;
4650     }
4651 
4652     if (ScavengeRootsInCode) {
4653       _g1h->register_nmethod(nm);
4654     }
4655   }
4656 };
4657 
4658 void G1CollectedHeap::rebuild_strong_code_roots() {
4659   RebuildStrongCodeRootClosure blob_cl(this);
4660   CodeCache::blobs_do(&blob_cl);
4661 }
4662 
4663 void G1CollectedHeap::initialize_serviceability() {
4664   _g1mm->initialize_serviceability();
4665 }
4666 
4667 MemoryUsage G1CollectedHeap::memory_usage() {
4668   return _g1mm->memory_usage();
4669 }
4670 
4671 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4672   return _g1mm->memory_managers();
4673 }
4674 
4675 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4676   return _g1mm->memory_pools();
4677 }