1 /*
   2  * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/metadataOnStackMark.hpp"
  27 #include "classfile/stringTable.hpp"
  28 #include "code/codeCache.hpp"
  29 #include "code/icBuffer.hpp"
  30 #include "gc/g1/g1Allocator.inline.hpp"
  31 #include "gc/g1/g1BarrierSet.hpp"
  32 #include "gc/g1/g1CollectedHeap.inline.hpp"
  33 #include "gc/g1/g1CollectionSet.hpp"
  34 #include "gc/g1/g1CollectorPolicy.hpp"
  35 #include "gc/g1/g1CollectorState.hpp"
  36 #include "gc/g1/g1ConcurrentRefine.hpp"
  37 #include "gc/g1/g1ConcurrentRefineThread.hpp"
  38 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
  39 #include "gc/g1/g1EvacStats.inline.hpp"
  40 #include "gc/g1/g1FullCollector.hpp"
  41 #include "gc/g1/g1GCPhaseTimes.hpp"
  42 #include "gc/g1/g1HeapSizingPolicy.hpp"
  43 #include "gc/g1/g1HeapTransition.hpp"
  44 #include "gc/g1/g1HeapVerifier.hpp"
  45 #include "gc/g1/g1HotCardCache.hpp"
  46 #include "gc/g1/g1MemoryPool.hpp"
  47 #include "gc/g1/g1OopClosures.inline.hpp"
  48 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  49 #include "gc/g1/g1Policy.hpp"
  50 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  51 #include "gc/g1/g1RemSet.hpp"
  52 #include "gc/g1/g1RootClosures.hpp"
  53 #include "gc/g1/g1RootProcessor.hpp"
  54 #include "gc/g1/g1SATBMarkQueueSet.hpp"
  55 #include "gc/g1/g1StringDedup.hpp"
  56 #include "gc/g1/g1ThreadLocalData.hpp"
  57 #include "gc/g1/g1YCTypes.hpp"
  58 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  59 #include "gc/g1/heapRegion.inline.hpp"
  60 #include "gc/g1/heapRegionRemSet.hpp"
  61 #include "gc/g1/heapRegionSet.inline.hpp"
  62 #include "gc/g1/vm_operations_g1.hpp"
  63 #include "gc/shared/adaptiveSizePolicy.hpp"
  64 #include "gc/shared/gcHeapSummary.hpp"
  65 #include "gc/shared/gcId.hpp"
  66 #include "gc/shared/gcLocker.hpp"
  67 #include "gc/shared/gcTimer.hpp"
  68 #include "gc/shared/gcTrace.hpp"
  69 #include "gc/shared/gcTraceTime.inline.hpp"
  70 #include "gc/shared/generationSpec.hpp"
  71 #include "gc/shared/isGCActiveMark.hpp"
  72 #include "gc/shared/oopStorageParState.hpp"
  73 #include "gc/shared/parallelCleaning.hpp"
  74 #include "gc/shared/preservedMarks.inline.hpp"
  75 #include "gc/shared/suspendibleThreadSet.hpp"
  76 #include "gc/shared/referenceProcessor.inline.hpp"
  77 #include "gc/shared/taskqueue.inline.hpp"
  78 #include "gc/shared/weakProcessor.inline.hpp"
  79 #include "logging/log.hpp"
  80 #include "memory/allocation.hpp"
  81 #include "memory/iterator.hpp"
  82 #include "memory/metaspaceShared.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(MetaspaceShared::is_archive_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_if_necessary_after_full_collection();
1047 
1048   // Rebuild the strong code root lists for each region
1049   rebuild_strong_code_roots();
1050 
1051   // Start a new incremental collection set for the next pause
1052   start_new_collection_set();
1053 
1054   _allocator->init_mutator_alloc_region();
1055 
1056   // Post collection state updates.
1057   MetaspaceGC::compute_new_size();
1058 }
1059 
1060 void G1CollectedHeap::abort_refinement() {
1061   if (_hot_card_cache->use_cache()) {
1062     _hot_card_cache->reset_hot_cache();
1063   }
1064 
1065   // Discard all remembered set updates.
1066   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1067   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1068 }
1069 
1070 void G1CollectedHeap::verify_after_full_collection() {
1071   _hrm.verify_optional();
1072   _verifier->verify_region_sets_optional();
1073   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1074   // Clear the previous marking bitmap, if needed for bitmap verification.
1075   // Note we cannot do this when we clear the next marking bitmap in
1076   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1077   // objects marked during a full GC against the previous bitmap.
1078   // But we need to clear it before calling check_bitmaps below since
1079   // the full GC has compacted objects and updated TAMS but not updated
1080   // the prev bitmap.
1081   if (G1VerifyBitmaps) {
1082     GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1083     _cm->clear_prev_bitmap(workers());
1084   }
1085   _verifier->check_bitmaps("Full GC End");
1086 
1087   // At this point there should be no regions in the
1088   // entire heap tagged as young.
1089   assert(check_young_list_empty(), "young list should be empty at this point");
1090 
1091   // Note: since we've just done a full GC, concurrent
1092   // marking is no longer active. Therefore we need not
1093   // re-enable reference discovery for the CM ref processor.
1094   // That will be done at the start of the next marking cycle.
1095   // We also know that the STW processor should no longer
1096   // discover any new references.
1097   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1098   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1099   _ref_processor_stw->verify_no_references_recorded();
1100   _ref_processor_cm->verify_no_references_recorded();
1101 }
1102 
1103 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1104   // Post collection logging.
1105   // We should do this after we potentially resize the heap so
1106   // that all the COMMIT / UNCOMMIT events are generated before
1107   // the compaction events.
1108   print_hrm_post_compaction();
1109   heap_transition->print();
1110   print_heap_after_gc();
1111   print_heap_regions();
1112 #ifdef TRACESPINNING
1113   ParallelTaskTerminator::print_termination_counts();
1114 #endif
1115 }
1116 
1117 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1118                                          bool clear_all_soft_refs) {
1119   assert_at_safepoint_on_vm_thread();
1120 
1121   if (GCLocker::check_active_before_gc()) {
1122     // Full GC was not completed.
1123     return false;
1124   }
1125 
1126   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1127       soft_ref_policy()->should_clear_all_soft_refs();
1128 
1129   G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1130   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1131 
1132   collector.prepare_collection();
1133   collector.collect();
1134   collector.complete_collection();
1135 
1136   // Full collection was successfully completed.
1137   return true;
1138 }
1139 
1140 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1141   // Currently, there is no facility in the do_full_collection(bool) API to notify
1142   // the caller that the collection did not succeed (e.g., because it was locked
1143   // out by the GC locker). So, right now, we'll ignore the return value.
1144   bool dummy = do_full_collection(true,                /* explicit_gc */
1145                                   clear_all_soft_refs);
1146 }
1147 
1148 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1149   // Capacity, free and used after the GC counted as full regions to
1150   // include the waste in the following calculations.
1151   const size_t capacity_after_gc = capacity();
1152   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1153 
1154   // This is enforced in arguments.cpp.
1155   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1156          "otherwise the code below doesn't make sense");
1157 
1158   // We don't have floating point command-line arguments
1159   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1160   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1161   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1162   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1163 
1164   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1165   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1166 
1167   // We have to be careful here as these two calculations can overflow
1168   // 32-bit size_t's.
1169   double used_after_gc_d = (double) used_after_gc;
1170   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1171   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1172 
1173   // Let's make sure that they are both under the max heap size, which
1174   // by default will make them fit into a size_t.
1175   double desired_capacity_upper_bound = (double) max_heap_size;
1176   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1177                                     desired_capacity_upper_bound);
1178   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1179                                     desired_capacity_upper_bound);
1180 
1181   // We can now safely turn them into size_t's.
1182   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1183   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1184 
1185   // This assert only makes sense here, before we adjust them
1186   // with respect to the min and max heap size.
1187   assert(minimum_desired_capacity <= maximum_desired_capacity,
1188          "minimum_desired_capacity = " SIZE_FORMAT ", "
1189          "maximum_desired_capacity = " SIZE_FORMAT,
1190          minimum_desired_capacity, maximum_desired_capacity);
1191 
1192   // Should not be greater than the heap max size. No need to adjust
1193   // it with respect to the heap min size as it's a lower bound (i.e.,
1194   // we'll try to make the capacity larger than it, not smaller).
1195   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1196   // Should not be less than the heap min size. No need to adjust it
1197   // with respect to the heap max size as it's an upper bound (i.e.,
1198   // we'll try to make the capacity smaller than it, not greater).
1199   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1200 
1201   if (capacity_after_gc < minimum_desired_capacity) {
1202     // Don't expand unless it's significant
1203     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1204 
1205     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1206                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1207                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1208                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1209 
1210     expand(expand_bytes, _workers);
1211 
1212     // No expansion, now see if we want to shrink
1213   } else if (capacity_after_gc > maximum_desired_capacity) {
1214     // Capacity too large, compute shrinking size
1215     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1216 
1217     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1218                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1219                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1220                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1221 
1222     shrink(shrink_bytes);
1223   }
1224 }
1225 
1226 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1227                                                             bool do_gc,
1228                                                             bool clear_all_soft_refs,
1229                                                             bool expect_null_mutator_alloc_region,
1230                                                             bool* gc_succeeded) {
1231   *gc_succeeded = true;
1232   // Let's attempt the allocation first.
1233   HeapWord* result =
1234     attempt_allocation_at_safepoint(word_size,
1235                                     expect_null_mutator_alloc_region);
1236   if (result != NULL) {
1237     return result;
1238   }
1239 
1240   // In a G1 heap, we're supposed to keep allocation from failing by
1241   // incremental pauses.  Therefore, at least for now, we'll favor
1242   // expansion over collection.  (This might change in the future if we can
1243   // do something smarter than full collection to satisfy a failed alloc.)
1244   result = expand_and_allocate(word_size);
1245   if (result != NULL) {
1246     return result;
1247   }
1248 
1249   if (do_gc) {
1250     // Expansion didn't work, we'll try to do a Full GC.
1251     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1252                                        clear_all_soft_refs);
1253   }
1254 
1255   return NULL;
1256 }
1257 
1258 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1259                                                      bool* succeeded) {
1260   assert_at_safepoint_on_vm_thread();
1261 
1262   // Attempts to allocate followed by Full GC.
1263   HeapWord* result =
1264     satisfy_failed_allocation_helper(word_size,
1265                                      true,  /* do_gc */
1266                                      false, /* clear_all_soft_refs */
1267                                      false, /* expect_null_mutator_alloc_region */
1268                                      succeeded);
1269 
1270   if (result != NULL || !*succeeded) {
1271     return result;
1272   }
1273 
1274   // Attempts to allocate followed by Full GC that will collect all soft references.
1275   result = satisfy_failed_allocation_helper(word_size,
1276                                             true, /* do_gc */
1277                                             true, /* clear_all_soft_refs */
1278                                             true, /* expect_null_mutator_alloc_region */
1279                                             succeeded);
1280 
1281   if (result != NULL || !*succeeded) {
1282     return result;
1283   }
1284 
1285   // Attempts to allocate, no GC
1286   result = satisfy_failed_allocation_helper(word_size,
1287                                             false, /* do_gc */
1288                                             false, /* clear_all_soft_refs */
1289                                             true,  /* expect_null_mutator_alloc_region */
1290                                             succeeded);
1291 
1292   if (result != NULL) {
1293     return result;
1294   }
1295 
1296   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1297          "Flag should have been handled and cleared prior to this point");
1298 
1299   // What else?  We might try synchronous finalization later.  If the total
1300   // space available is large enough for the allocation, then a more
1301   // complete compaction phase than we've tried so far might be
1302   // appropriate.
1303   return NULL;
1304 }
1305 
1306 // Attempting to expand the heap sufficiently
1307 // to support an allocation of the given "word_size".  If
1308 // successful, perform the allocation and return the address of the
1309 // allocated block, or else "NULL".
1310 
1311 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1312   assert_at_safepoint_on_vm_thread();
1313 
1314   _verifier->verify_region_sets_optional();
1315 
1316   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1317   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1318                             word_size * HeapWordSize);
1319 
1320 
1321   if (expand(expand_bytes, _workers)) {
1322     _hrm.verify_optional();
1323     _verifier->verify_region_sets_optional();
1324     return attempt_allocation_at_safepoint(word_size,
1325                                            false /* expect_null_mutator_alloc_region */);
1326   }
1327   return NULL;
1328 }
1329 
1330 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1331   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1332   aligned_expand_bytes = align_up(aligned_expand_bytes,
1333                                        HeapRegion::GrainBytes);
1334 
1335   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1336                             expand_bytes, aligned_expand_bytes);
1337 
1338   if (is_maximal_no_gc()) {
1339     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1340     return false;
1341   }
1342 
1343   double expand_heap_start_time_sec = os::elapsedTime();
1344   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1345   assert(regions_to_expand > 0, "Must expand by at least one region");
1346 
1347   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1348   if (expand_time_ms != NULL) {
1349     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1350   }
1351 
1352   if (expanded_by > 0) {
1353     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1354     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1355     g1_policy()->record_new_heap_size(num_regions());
1356   } else {
1357     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1358 
1359     // The expansion of the virtual storage space was unsuccessful.
1360     // Let's see if it was because we ran out of swap.
1361     if (G1ExitOnExpansionFailure &&
1362         _hrm.available() >= regions_to_expand) {
1363       // We had head room...
1364       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1365     }
1366   }
1367   return regions_to_expand > 0;
1368 }
1369 
1370 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1371   size_t aligned_shrink_bytes =
1372     ReservedSpace::page_align_size_down(shrink_bytes);
1373   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1374                                          HeapRegion::GrainBytes);
1375   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1376 
1377   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1378   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1379 
1380 
1381   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",
1382                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1383   if (num_regions_removed > 0) {
1384     g1_policy()->record_new_heap_size(num_regions());
1385   } else {
1386     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1387   }
1388 }
1389 
1390 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1391   _verifier->verify_region_sets_optional();
1392 
1393   // We should only reach here at the end of a Full GC which means we
1394   // should not not be holding to any GC alloc regions. The method
1395   // below will make sure of that and do any remaining clean up.
1396   _allocator->abandon_gc_alloc_regions();
1397 
1398   // Instead of tearing down / rebuilding the free lists here, we
1399   // could instead use the remove_all_pending() method on free_list to
1400   // remove only the ones that we need to remove.
1401   tear_down_region_sets(true /* free_list_only */);
1402   shrink_helper(shrink_bytes);
1403   rebuild_region_sets(true /* free_list_only */);
1404 
1405   _hrm.verify_optional();
1406   _verifier->verify_region_sets_optional();
1407 }
1408 
1409 class OldRegionSetChecker : public HeapRegionSetChecker {
1410 public:
1411   void check_mt_safety() {
1412     // Master Old Set MT safety protocol:
1413     // (a) If we're at a safepoint, operations on the master old set
1414     // should be invoked:
1415     // - by the VM thread (which will serialize them), or
1416     // - by the GC workers while holding the FreeList_lock, if we're
1417     //   at a safepoint for an evacuation pause (this lock is taken
1418     //   anyway when an GC alloc region is retired so that a new one
1419     //   is allocated from the free list), or
1420     // - by the GC workers while holding the OldSets_lock, if we're at a
1421     //   safepoint for a cleanup pause.
1422     // (b) If we're not at a safepoint, operations on the master old set
1423     // should be invoked while holding the Heap_lock.
1424 
1425     if (SafepointSynchronize::is_at_safepoint()) {
1426       guarantee(Thread::current()->is_VM_thread() ||
1427                 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1428                 "master old set MT safety protocol at a safepoint");
1429     } else {
1430       guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1431     }
1432   }
1433   bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1434   const char* get_description() { return "Old Regions"; }
1435 };
1436 
1437 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1438 public:
1439   void check_mt_safety() {
1440     guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1441               "May only change archive regions during initialization or safepoint.");
1442   }
1443   bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1444   const char* get_description() { return "Archive Regions"; }
1445 };
1446 
1447 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1448 public:
1449   void check_mt_safety() {
1450     // Humongous Set MT safety protocol:
1451     // (a) If we're at a safepoint, operations on the master humongous
1452     // set should be invoked by either the VM thread (which will
1453     // serialize them) or by the GC workers while holding the
1454     // OldSets_lock.
1455     // (b) If we're not at a safepoint, operations on the master
1456     // humongous set should be invoked while holding the Heap_lock.
1457 
1458     if (SafepointSynchronize::is_at_safepoint()) {
1459       guarantee(Thread::current()->is_VM_thread() ||
1460                 OldSets_lock->owned_by_self(),
1461                 "master humongous set MT safety protocol at a safepoint");
1462     } else {
1463       guarantee(Heap_lock->owned_by_self(),
1464                 "master humongous set MT safety protocol outside a safepoint");
1465     }
1466   }
1467   bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1468   const char* get_description() { return "Humongous Regions"; }
1469 };
1470 
1471 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1472   CollectedHeap(),
1473   _young_gen_sampling_thread(NULL),
1474   _workers(NULL),
1475   _collector_policy(collector_policy),
1476   _card_table(NULL),
1477   _soft_ref_policy(),
1478   _old_set("Old Region Set", new OldRegionSetChecker()),
1479   _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1480   _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1481   _bot(NULL),
1482   _listener(),
1483   _hrm(),
1484   _allocator(NULL),
1485   _verifier(NULL),
1486   _summary_bytes_used(0),
1487   _archive_allocator(NULL),
1488   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1489   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1490   _expand_heap_after_alloc_failure(true),
1491   _g1mm(NULL),
1492   _humongous_reclaim_candidates(),
1493   _has_humongous_reclaim_candidates(false),
1494   _hr_printer(),
1495   _collector_state(),
1496   _old_marking_cycles_started(0),
1497   _old_marking_cycles_completed(0),
1498   _eden(),
1499   _survivor(),
1500   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1501   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1502   _g1_policy(new G1Policy(_gc_timer_stw)),
1503   _heap_sizing_policy(NULL),
1504   _collection_set(this, _g1_policy),
1505   _hot_card_cache(NULL),
1506   _g1_rem_set(NULL),
1507   _dirty_card_queue_set(false),
1508   _cm(NULL),
1509   _cm_thread(NULL),
1510   _cr(NULL),
1511   _task_queues(NULL),
1512   _evacuation_failed(false),
1513   _evacuation_failed_info_array(NULL),
1514   _preserved_marks_set(true /* in_c_heap */),
1515 #ifndef PRODUCT
1516   _evacuation_failure_alot_for_current_gc(false),
1517   _evacuation_failure_alot_gc_number(0),
1518   _evacuation_failure_alot_count(0),
1519 #endif
1520   _ref_processor_stw(NULL),
1521   _is_alive_closure_stw(this),
1522   _is_subject_to_discovery_stw(this),
1523   _ref_processor_cm(NULL),
1524   _is_alive_closure_cm(this),
1525   _is_subject_to_discovery_cm(this),
1526   _in_cset_fast_test() {
1527 
1528   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1529                           true /* are_GC_task_threads */,
1530                           false /* are_ConcurrentGC_threads */);
1531   _workers->initialize_workers();
1532   _verifier = new G1HeapVerifier(this);
1533 
1534   _allocator = new G1Allocator(this);
1535 
1536   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1537 
1538   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1539 
1540   // Override the default _filler_array_max_size so that no humongous filler
1541   // objects are created.
1542   _filler_array_max_size = _humongous_object_threshold_in_words;
1543 
1544   uint n_queues = ParallelGCThreads;
1545   _task_queues = new RefToScanQueueSet(n_queues);
1546 
1547   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1548 
1549   for (uint i = 0; i < n_queues; i++) {
1550     RefToScanQueue* q = new RefToScanQueue();
1551     q->initialize();
1552     _task_queues->register_queue(i, q);
1553     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1554   }
1555 
1556   // Initialize the G1EvacuationFailureALot counters and flags.
1557   NOT_PRODUCT(reset_evacuation_should_fail();)
1558 
1559   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1560 }
1561 
1562 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1563                                                                  size_t size,
1564                                                                  size_t translation_factor) {
1565   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1566   // Allocate a new reserved space, preferring to use large pages.
1567   ReservedSpace rs(size, preferred_page_size);
1568   G1RegionToSpaceMapper* result  =
1569     G1RegionToSpaceMapper::create_mapper(rs,
1570                                          size,
1571                                          rs.alignment(),
1572                                          HeapRegion::GrainBytes,
1573                                          translation_factor,
1574                                          mtGC);
1575 
1576   os::trace_page_sizes_for_requested_size(description,
1577                                           size,
1578                                           preferred_page_size,
1579                                           rs.alignment(),
1580                                           rs.base(),
1581                                           rs.size());
1582 
1583   return result;
1584 }
1585 
1586 jint G1CollectedHeap::initialize_concurrent_refinement() {
1587   jint ecode = JNI_OK;
1588   _cr = G1ConcurrentRefine::create(&ecode);
1589   return ecode;
1590 }
1591 
1592 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1593   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1594   if (_young_gen_sampling_thread->osthread() == NULL) {
1595     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1596     return JNI_ENOMEM;
1597   }
1598   return JNI_OK;
1599 }
1600 
1601 jint G1CollectedHeap::initialize() {
1602   os::enable_vtime();
1603 
1604   // Necessary to satisfy locking discipline assertions.
1605 
1606   MutexLocker x(Heap_lock);
1607 
1608   // While there are no constraints in the GC code that HeapWordSize
1609   // be any particular value, there are multiple other areas in the
1610   // system which believe this to be true (e.g. oop->object_size in some
1611   // cases incorrectly returns the size in wordSize units rather than
1612   // HeapWordSize).
1613   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1614 
1615   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1616   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1617   size_t heap_alignment = collector_policy()->heap_alignment();
1618 
1619   // Ensure that the sizes are properly aligned.
1620   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1621   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1622   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1623 
1624   // Reserve the maximum.
1625 
1626   // When compressed oops are enabled, the preferred heap base
1627   // is calculated by subtracting the requested size from the
1628   // 32Gb boundary and using the result as the base address for
1629   // heap reservation. If the requested size is not aligned to
1630   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1631   // into the ReservedHeapSpace constructor) then the actual
1632   // base of the reserved heap may end up differing from the
1633   // address that was requested (i.e. the preferred heap base).
1634   // If this happens then we could end up using a non-optimal
1635   // compressed oops mode.
1636 
1637   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1638                                                  heap_alignment);
1639 
1640   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1641 
1642   // Create the barrier set for the entire reserved region.
1643   G1CardTable* ct = new G1CardTable(reserved_region());
1644   ct->initialize();
1645   G1BarrierSet* bs = new G1BarrierSet(ct);
1646   bs->initialize();
1647   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1648   BarrierSet::set_barrier_set(bs);
1649   _card_table = ct;
1650 
1651   // Create the hot card cache.
1652   _hot_card_cache = new G1HotCardCache(this);
1653 
1654   // Carve out the G1 part of the heap.
1655   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1656   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1657   G1RegionToSpaceMapper* heap_storage =
1658     G1RegionToSpaceMapper::create_mapper(g1_rs,
1659                                          g1_rs.size(),
1660                                          page_size,
1661                                          HeapRegion::GrainBytes,
1662                                          1,
1663                                          mtJavaHeap);
1664   os::trace_page_sizes("Heap",
1665                        collector_policy()->min_heap_byte_size(),
1666                        max_byte_size,
1667                        page_size,
1668                        heap_rs.base(),
1669                        heap_rs.size());
1670   heap_storage->set_mapping_changed_listener(&_listener);
1671 
1672   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1673   G1RegionToSpaceMapper* bot_storage =
1674     create_aux_memory_mapper("Block Offset Table",
1675                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1676                              G1BlockOffsetTable::heap_map_factor());
1677 
1678   G1RegionToSpaceMapper* cardtable_storage =
1679     create_aux_memory_mapper("Card Table",
1680                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1681                              G1CardTable::heap_map_factor());
1682 
1683   G1RegionToSpaceMapper* card_counts_storage =
1684     create_aux_memory_mapper("Card Counts Table",
1685                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1686                              G1CardCounts::heap_map_factor());
1687 
1688   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1689   G1RegionToSpaceMapper* prev_bitmap_storage =
1690     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1691   G1RegionToSpaceMapper* next_bitmap_storage =
1692     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1693 
1694   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1695   _card_table->initialize(cardtable_storage);
1696   // Do later initialization work for concurrent refinement.
1697   _hot_card_cache->initialize(card_counts_storage);
1698 
1699   // 6843694 - ensure that the maximum region index can fit
1700   // in the remembered set structures.
1701   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1702   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1703 
1704   // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1705   // start within the first card.
1706   guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1707   // Also create a G1 rem set.
1708   _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1709   _g1_rem_set->initialize(max_capacity(), max_regions());
1710 
1711   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1712   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1713   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1714             "too many cards per region");
1715 
1716   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1717 
1718   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1719 
1720   {
1721     HeapWord* start = _hrm.reserved().start();
1722     HeapWord* end = _hrm.reserved().end();
1723     size_t granularity = HeapRegion::GrainBytes;
1724 
1725     _in_cset_fast_test.initialize(start, end, granularity);
1726     _humongous_reclaim_candidates.initialize(start, end, granularity);
1727   }
1728 
1729   // Create the G1ConcurrentMark data structure and thread.
1730   // (Must do this late, so that "max_regions" is defined.)
1731   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1732   if (_cm == NULL || !_cm->completed_initialization()) {
1733     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1734     return JNI_ENOMEM;
1735   }
1736   _cm_thread = _cm->cm_thread();
1737 
1738   // Now expand into the initial heap size.
1739   if (!expand(init_byte_size, _workers)) {
1740     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1741     return JNI_ENOMEM;
1742   }
1743 
1744   // Perform any initialization actions delegated to the policy.
1745   g1_policy()->init(this, &_collection_set);
1746 
1747   G1BarrierSet::satb_mark_queue_set().initialize(this,
1748                                                  SATB_Q_CBL_mon,
1749                                                  SATB_Q_FL_lock,
1750                                                  G1SATBProcessCompletedThreshold,
1751                                                  G1SATBBufferEnqueueingThresholdPercent,
1752                                                  Shared_SATB_Q_lock);
1753 
1754   jint ecode = initialize_concurrent_refinement();
1755   if (ecode != JNI_OK) {
1756     return ecode;
1757   }
1758 
1759   ecode = initialize_young_gen_sampling_thread();
1760   if (ecode != JNI_OK) {
1761     return ecode;
1762   }
1763 
1764   G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1765                                                   DirtyCardQ_FL_lock,
1766                                                   (int)concurrent_refine()->yellow_zone(),
1767                                                   (int)concurrent_refine()->red_zone(),
1768                                                   Shared_DirtyCardQ_lock,
1769                                                   NULL,  // fl_owner
1770                                                   true); // init_free_ids
1771 
1772   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1773                                     DirtyCardQ_FL_lock,
1774                                     -1, // never trigger processing
1775                                     -1, // no limit on length
1776                                     Shared_DirtyCardQ_lock,
1777                                     &G1BarrierSet::dirty_card_queue_set());
1778 
1779   // Here we allocate the dummy HeapRegion that is required by the
1780   // G1AllocRegion class.
1781   HeapRegion* dummy_region = _hrm.get_dummy_region();
1782 
1783   // We'll re-use the same region whether the alloc region will
1784   // require BOT updates or not and, if it doesn't, then a non-young
1785   // region will complain that it cannot support allocations without
1786   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1787   dummy_region->set_eden();
1788   // Make sure it's full.
1789   dummy_region->set_top(dummy_region->end());
1790   G1AllocRegion::setup(this, dummy_region);
1791 
1792   _allocator->init_mutator_alloc_region();
1793 
1794   // Do create of the monitoring and management support so that
1795   // values in the heap have been properly initialized.
1796   _g1mm = new G1MonitoringSupport(this);
1797 
1798   G1StringDedup::initialize();
1799 
1800   _preserved_marks_set.init(ParallelGCThreads);
1801 
1802   _collection_set.initialize(max_regions());
1803 
1804   return JNI_OK;
1805 }
1806 
1807 void G1CollectedHeap::stop() {
1808   // Stop all concurrent threads. We do this to make sure these threads
1809   // do not continue to execute and access resources (e.g. logging)
1810   // that are destroyed during shutdown.
1811   _cr->stop();
1812   _young_gen_sampling_thread->stop();
1813   _cm_thread->stop();
1814   if (G1StringDedup::is_enabled()) {
1815     G1StringDedup::stop();
1816   }
1817 }
1818 
1819 void G1CollectedHeap::safepoint_synchronize_begin() {
1820   SuspendibleThreadSet::synchronize();
1821 }
1822 
1823 void G1CollectedHeap::safepoint_synchronize_end() {
1824   SuspendibleThreadSet::desynchronize();
1825 }
1826 
1827 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1828   return HeapRegion::max_region_size();
1829 }
1830 
1831 void G1CollectedHeap::post_initialize() {
1832   CollectedHeap::post_initialize();
1833   ref_processing_init();
1834 }
1835 
1836 void G1CollectedHeap::ref_processing_init() {
1837   // Reference processing in G1 currently works as follows:
1838   //
1839   // * There are two reference processor instances. One is
1840   //   used to record and process discovered references
1841   //   during concurrent marking; the other is used to
1842   //   record and process references during STW pauses
1843   //   (both full and incremental).
1844   // * Both ref processors need to 'span' the entire heap as
1845   //   the regions in the collection set may be dotted around.
1846   //
1847   // * For the concurrent marking ref processor:
1848   //   * Reference discovery is enabled at initial marking.
1849   //   * Reference discovery is disabled and the discovered
1850   //     references processed etc during remarking.
1851   //   * Reference discovery is MT (see below).
1852   //   * Reference discovery requires a barrier (see below).
1853   //   * Reference processing may or may not be MT
1854   //     (depending on the value of ParallelRefProcEnabled
1855   //     and ParallelGCThreads).
1856   //   * A full GC disables reference discovery by the CM
1857   //     ref processor and abandons any entries on it's
1858   //     discovered lists.
1859   //
1860   // * For the STW processor:
1861   //   * Non MT discovery is enabled at the start of a full GC.
1862   //   * Processing and enqueueing during a full GC is non-MT.
1863   //   * During a full GC, references are processed after marking.
1864   //
1865   //   * Discovery (may or may not be MT) is enabled at the start
1866   //     of an incremental evacuation pause.
1867   //   * References are processed near the end of a STW evacuation pause.
1868   //   * For both types of GC:
1869   //     * Discovery is atomic - i.e. not concurrent.
1870   //     * Reference discovery will not need a barrier.
1871 
1872   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1873 
1874   // Concurrent Mark ref processor
1875   _ref_processor_cm =
1876     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1877                            mt_processing,                                  // mt processing
1878                            ParallelGCThreads,                              // degree of mt processing
1879                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1880                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1881                            false,                                          // Reference discovery is not atomic
1882                            &_is_alive_closure_cm,                          // is alive closure
1883                            true);                                          // allow changes to number of processing threads
1884 
1885   // STW ref processor
1886   _ref_processor_stw =
1887     new ReferenceProcessor(&_is_subject_to_discovery_stw,
1888                            mt_processing,                        // mt processing
1889                            ParallelGCThreads,                    // degree of mt processing
1890                            (ParallelGCThreads > 1),              // mt discovery
1891                            ParallelGCThreads,                    // degree of mt discovery
1892                            true,                                 // Reference discovery is atomic
1893                            &_is_alive_closure_stw,               // is alive closure
1894                            true);                                // allow changes to number of processing threads
1895 }
1896 
1897 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1898   return _collector_policy;
1899 }
1900 
1901 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1902   return &_soft_ref_policy;
1903 }
1904 
1905 size_t G1CollectedHeap::capacity() const {
1906   return _hrm.length() * HeapRegion::GrainBytes;
1907 }
1908 
1909 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1910   return _hrm.total_free_bytes();
1911 }
1912 
1913 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1914   _hot_card_cache->drain(cl, worker_i);
1915 }
1916 
1917 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1918   DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1919   size_t n_completed_buffers = 0;
1920   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1921     n_completed_buffers++;
1922   }
1923   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1924   dcqs.clear_n_completed_buffers();
1925   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1926 }
1927 
1928 // Computes the sum of the storage used by the various regions.
1929 size_t G1CollectedHeap::used() const {
1930   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1931   if (_archive_allocator != NULL) {
1932     result += _archive_allocator->used();
1933   }
1934   return result;
1935 }
1936 
1937 size_t G1CollectedHeap::used_unlocked() const {
1938   return _summary_bytes_used;
1939 }
1940 
1941 class SumUsedClosure: public HeapRegionClosure {
1942   size_t _used;
1943 public:
1944   SumUsedClosure() : _used(0) {}
1945   bool do_heap_region(HeapRegion* r) {
1946     _used += r->used();
1947     return false;
1948   }
1949   size_t result() { return _used; }
1950 };
1951 
1952 size_t G1CollectedHeap::recalculate_used() const {
1953   double recalculate_used_start = os::elapsedTime();
1954 
1955   SumUsedClosure blk;
1956   heap_region_iterate(&blk);
1957 
1958   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
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   accumulate_statistics_all_tlabs();
2492   ensure_parsability(true);
2493   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2494 }
2495 
2496 void G1CollectedHeap::gc_epilogue(bool full) {
2497   // Update common counters.
2498   if (full) {
2499     // Update the number of full collections that have been completed.
2500     increment_old_marking_cycles_completed(false /* concurrent */);
2501   }
2502 
2503   // We are at the end of the GC. Total collections has already been increased.
2504   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2505 
2506   // FIXME: what is this about?
2507   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2508   // is set.
2509 #if COMPILER2_OR_JVMCI
2510   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2511 #endif
2512   // always_do_update_barrier = true;
2513 
2514   double start = os::elapsedTime();
2515   resize_all_tlabs();
2516   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2517 
2518   MemoryService::track_memory_usage();
2519   // We have just completed a GC. Update the soft reference
2520   // policy with the new heap occupancy
2521   Universe::update_heap_info_at_gc();
2522 }
2523 
2524 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2525                                                uint gc_count_before,
2526                                                bool* succeeded,
2527                                                GCCause::Cause gc_cause) {
2528   assert_heap_not_locked_and_not_at_safepoint();
2529   VM_G1CollectForAllocation op(word_size,
2530                                gc_count_before,
2531                                gc_cause,
2532                                false, /* should_initiate_conc_mark */
2533                                g1_policy()->max_pause_time_ms());
2534   VMThread::execute(&op);
2535 
2536   HeapWord* result = op.result();
2537   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2538   assert(result == NULL || ret_succeeded,
2539          "the result should be NULL if the VM did not succeed");
2540   *succeeded = ret_succeeded;
2541 
2542   assert_heap_not_locked();
2543   return result;
2544 }
2545 
2546 void G1CollectedHeap::do_concurrent_mark() {
2547   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2548   if (!_cm_thread->in_progress()) {
2549     _cm_thread->set_started();
2550     CGC_lock->notify();
2551   }
2552 }
2553 
2554 size_t G1CollectedHeap::pending_card_num() {
2555   size_t extra_cards = 0;
2556   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2557     DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2558     extra_cards += dcq.size();
2559   }
2560   DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2561   size_t buffer_size = dcqs.buffer_size();
2562   size_t buffer_num = dcqs.completed_buffers_num();
2563 
2564   return buffer_size * buffer_num + extra_cards;
2565 }
2566 
2567 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2568   // We don't nominate objects with many remembered set entries, on
2569   // the assumption that such objects are likely still live.
2570   HeapRegionRemSet* rem_set = r->rem_set();
2571 
2572   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2573          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2574          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2575 }
2576 
2577 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2578  private:
2579   size_t _total_humongous;
2580   size_t _candidate_humongous;
2581 
2582   DirtyCardQueue _dcq;
2583 
2584   bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2585     assert(region->is_starts_humongous(), "Must start a humongous object");
2586 
2587     oop obj = oop(region->bottom());
2588 
2589     // Dead objects cannot be eager reclaim candidates. Due to class
2590     // unloading it is unsafe to query their classes so we return early.
2591     if (g1h->is_obj_dead(obj, region)) {
2592       return false;
2593     }
2594 
2595     // If we do not have a complete remembered set for the region, then we can
2596     // not be sure that we have all references to it.
2597     if (!region->rem_set()->is_complete()) {
2598       return false;
2599     }
2600     // Candidate selection must satisfy the following constraints
2601     // while concurrent marking is in progress:
2602     //
2603     // * In order to maintain SATB invariants, an object must not be
2604     // reclaimed if it was allocated before the start of marking and
2605     // has not had its references scanned.  Such an object must have
2606     // its references (including type metadata) scanned to ensure no
2607     // live objects are missed by the marking process.  Objects
2608     // allocated after the start of concurrent marking don't need to
2609     // be scanned.
2610     //
2611     // * An object must not be reclaimed if it is on the concurrent
2612     // mark stack.  Objects allocated after the start of concurrent
2613     // marking are never pushed on the mark stack.
2614     //
2615     // Nominating only objects allocated after the start of concurrent
2616     // marking is sufficient to meet both constraints.  This may miss
2617     // some objects that satisfy the constraints, but the marking data
2618     // structures don't support efficiently performing the needed
2619     // additional tests or scrubbing of the mark stack.
2620     //
2621     // However, we presently only nominate is_typeArray() objects.
2622     // A humongous object containing references induces remembered
2623     // set entries on other regions.  In order to reclaim such an
2624     // object, those remembered sets would need to be cleaned up.
2625     //
2626     // We also treat is_typeArray() objects specially, allowing them
2627     // to be reclaimed even if allocated before the start of
2628     // concurrent mark.  For this we rely on mark stack insertion to
2629     // exclude is_typeArray() objects, preventing reclaiming an object
2630     // that is in the mark stack.  We also rely on the metadata for
2631     // such objects to be built-in and so ensured to be kept live.
2632     // Frequent allocation and drop of large binary blobs is an
2633     // important use case for eager reclaim, and this special handling
2634     // may reduce needed headroom.
2635 
2636     return obj->is_typeArray() &&
2637            g1h->is_potential_eager_reclaim_candidate(region);
2638   }
2639 
2640  public:
2641   RegisterHumongousWithInCSetFastTestClosure()
2642   : _total_humongous(0),
2643     _candidate_humongous(0),
2644     _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2645   }
2646 
2647   virtual bool do_heap_region(HeapRegion* r) {
2648     if (!r->is_starts_humongous()) {
2649       return false;
2650     }
2651     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2652 
2653     bool is_candidate = humongous_region_is_candidate(g1h, r);
2654     uint rindex = r->hrm_index();
2655     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2656     if (is_candidate) {
2657       _candidate_humongous++;
2658       g1h->register_humongous_region_with_cset(rindex);
2659       // Is_candidate already filters out humongous object with large remembered sets.
2660       // If we have a humongous object with a few remembered sets, we simply flush these
2661       // remembered set entries into the DCQS. That will result in automatic
2662       // re-evaluation of their remembered set entries during the following evacuation
2663       // phase.
2664       if (!r->rem_set()->is_empty()) {
2665         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2666                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2667         G1CardTable* ct = g1h->card_table();
2668         HeapRegionRemSetIterator hrrs(r->rem_set());
2669         size_t card_index;
2670         while (hrrs.has_next(card_index)) {
2671           jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2672           // The remembered set might contain references to already freed
2673           // regions. Filter out such entries to avoid failing card table
2674           // verification.
2675           if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2676             if (*card_ptr != G1CardTable::dirty_card_val()) {
2677               *card_ptr = G1CardTable::dirty_card_val();
2678               _dcq.enqueue(card_ptr);
2679             }
2680           }
2681         }
2682         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2683                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2684                hrrs.n_yielded(), r->rem_set()->occupied());
2685         // We should only clear the card based remembered set here as we will not
2686         // implicitly rebuild anything else during eager reclaim. Note that at the moment
2687         // (and probably never) we do not enter this path if there are other kind of
2688         // remembered sets for this region.
2689         r->rem_set()->clear_locked(true /* only_cardset */);
2690         // Clear_locked() above sets the state to Empty. However we want to continue
2691         // collecting remembered set entries for humongous regions that were not
2692         // reclaimed.
2693         r->rem_set()->set_state_complete();
2694       }
2695       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2696     }
2697     _total_humongous++;
2698 
2699     return false;
2700   }
2701 
2702   size_t total_humongous() const { return _total_humongous; }
2703   size_t candidate_humongous() const { return _candidate_humongous; }
2704 
2705   void flush_rem_set_entries() { _dcq.flush(); }
2706 };
2707 
2708 void G1CollectedHeap::register_humongous_regions_with_cset() {
2709   if (!G1EagerReclaimHumongousObjects) {
2710     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2711     return;
2712   }
2713   double time = os::elapsed_counter();
2714 
2715   // Collect reclaim candidate information and register candidates with cset.
2716   RegisterHumongousWithInCSetFastTestClosure cl;
2717   heap_region_iterate(&cl);
2718 
2719   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2720   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2721                                                                   cl.total_humongous(),
2722                                                                   cl.candidate_humongous());
2723   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2724 
2725   // Finally flush all remembered set entries to re-check into the global DCQS.
2726   cl.flush_rem_set_entries();
2727 }
2728 
2729 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2730   public:
2731     bool do_heap_region(HeapRegion* hr) {
2732       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2733         hr->verify_rem_set();
2734       }
2735       return false;
2736     }
2737 };
2738 
2739 uint G1CollectedHeap::num_task_queues() const {
2740   return _task_queues->size();
2741 }
2742 
2743 #if TASKQUEUE_STATS
2744 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2745   st->print_raw_cr("GC Task Stats");
2746   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2747   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2748 }
2749 
2750 void G1CollectedHeap::print_taskqueue_stats() const {
2751   if (!log_is_enabled(Trace, gc, task, stats)) {
2752     return;
2753   }
2754   Log(gc, task, stats) log;
2755   ResourceMark rm;
2756   LogStream ls(log.trace());
2757   outputStream* st = &ls;
2758 
2759   print_taskqueue_stats_hdr(st);
2760 
2761   TaskQueueStats totals;
2762   const uint n = num_task_queues();
2763   for (uint i = 0; i < n; ++i) {
2764     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2765     totals += task_queue(i)->stats;
2766   }
2767   st->print_raw("tot "); totals.print(st); st->cr();
2768 
2769   DEBUG_ONLY(totals.verify());
2770 }
2771 
2772 void G1CollectedHeap::reset_taskqueue_stats() {
2773   const uint n = num_task_queues();
2774   for (uint i = 0; i < n; ++i) {
2775     task_queue(i)->stats.reset();
2776   }
2777 }
2778 #endif // TASKQUEUE_STATS
2779 
2780 void G1CollectedHeap::wait_for_root_region_scanning() {
2781   double scan_wait_start = os::elapsedTime();
2782   // We have to wait until the CM threads finish scanning the
2783   // root regions as it's the only way to ensure that all the
2784   // objects on them have been correctly scanned before we start
2785   // moving them during the GC.
2786   bool waited = _cm->root_regions()->wait_until_scan_finished();
2787   double wait_time_ms = 0.0;
2788   if (waited) {
2789     double scan_wait_end = os::elapsedTime();
2790     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2791   }
2792   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2793 }
2794 
2795 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2796 private:
2797   G1HRPrinter* _hr_printer;
2798 public:
2799   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2800 
2801   virtual bool do_heap_region(HeapRegion* r) {
2802     _hr_printer->cset(r);
2803     return false;
2804   }
2805 };
2806 
2807 void G1CollectedHeap::start_new_collection_set() {
2808   collection_set()->start_incremental_building();
2809 
2810   clear_cset_fast_test();
2811 
2812   guarantee(_eden.length() == 0, "eden should have been cleared");
2813   g1_policy()->transfer_survivors_to_cset(survivor());
2814 }
2815 
2816 bool
2817 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2818   assert_at_safepoint_on_vm_thread();
2819   guarantee(!is_gc_active(), "collection is not reentrant");
2820 
2821   if (GCLocker::check_active_before_gc()) {
2822     return false;
2823   }
2824 
2825   _gc_timer_stw->register_gc_start();
2826 
2827   GCIdMark gc_id_mark;
2828   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2829 
2830   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2831   ResourceMark rm;
2832 
2833   g1_policy()->note_gc_start();
2834 
2835   wait_for_root_region_scanning();
2836 
2837   print_heap_before_gc();
2838   print_heap_regions();
2839   trace_heap_before_gc(_gc_tracer_stw);
2840 
2841   _verifier->verify_region_sets_optional();
2842   _verifier->verify_dirty_young_regions();
2843 
2844   // We should not be doing initial mark unless the conc mark thread is running
2845   if (!_cm_thread->should_terminate()) {
2846     // This call will decide whether this pause is an initial-mark
2847     // pause. If it is, in_initial_mark_gc() will return true
2848     // for the duration of this pause.
2849     g1_policy()->decide_on_conc_mark_initiation();
2850   }
2851 
2852   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2853   assert(!collector_state()->in_initial_mark_gc() ||
2854           collector_state()->in_young_only_phase(), "sanity");
2855 
2856   // We also do not allow mixed GCs during marking.
2857   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2858 
2859   // Record whether this pause is an initial mark. When the current
2860   // thread has completed its logging output and it's safe to signal
2861   // the CM thread, the flag's value in the policy has been reset.
2862   bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2863 
2864   // Inner scope for scope based logging, timers, and stats collection
2865   {
2866     EvacuationInfo evacuation_info;
2867 
2868     if (collector_state()->in_initial_mark_gc()) {
2869       // We are about to start a marking cycle, so we increment the
2870       // full collection counter.
2871       increment_old_marking_cycles_started();
2872       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2873     }
2874 
2875     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2876 
2877     GCTraceCPUTime tcpu;
2878 
2879     G1HeapVerifier::G1VerifyType verify_type;
2880     FormatBuffer<> gc_string("Pause Young ");
2881     if (collector_state()->in_initial_mark_gc()) {
2882       gc_string.append("(Concurrent Start)");
2883       verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2884     } else if (collector_state()->in_young_only_phase()) {
2885       if (collector_state()->in_young_gc_before_mixed()) {
2886         gc_string.append("(Prepare Mixed)");
2887       } else {
2888         gc_string.append("(Normal)");
2889       }
2890       verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2891     } else {
2892       gc_string.append("(Mixed)");
2893       verify_type = G1HeapVerifier::G1VerifyMixed;
2894     }
2895     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2896 
2897     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2898                                                                   workers()->active_workers(),
2899                                                                   Threads::number_of_non_daemon_threads());
2900     active_workers = workers()->update_active_workers(active_workers);
2901     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2902 
2903     G1MonitoringScope ms(g1mm(),
2904                          false /* full_gc */,
2905                          collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2906 
2907     G1HeapTransition heap_transition(this);
2908     size_t heap_used_bytes_before_gc = used();
2909 
2910     // Don't dynamically change the number of GC threads this early.  A value of
2911     // 0 is used to indicate serial work.  When parallel work is done,
2912     // it will be set.
2913 
2914     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2915       IsGCActiveMark x;
2916 
2917       gc_prologue(false);
2918 
2919       if (VerifyRememberedSets) {
2920         log_info(gc, verify)("[Verifying RemSets before GC]");
2921         VerifyRegionRemSetClosure v_cl;
2922         heap_region_iterate(&v_cl);
2923       }
2924 
2925       _verifier->verify_before_gc(verify_type);
2926 
2927       _verifier->check_bitmaps("GC Start");
2928 
2929 #if COMPILER2_OR_JVMCI
2930       DerivedPointerTable::clear();
2931 #endif
2932 
2933       // Please see comment in g1CollectedHeap.hpp and
2934       // G1CollectedHeap::ref_processing_init() to see how
2935       // reference processing currently works in G1.
2936 
2937       // Enable discovery in the STW reference processor
2938       _ref_processor_stw->enable_discovery();
2939 
2940       {
2941         // We want to temporarily turn off discovery by the
2942         // CM ref processor, if necessary, and turn it back on
2943         // on again later if we do. Using a scoped
2944         // NoRefDiscovery object will do this.
2945         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2946 
2947         // Forget the current alloc region (we might even choose it to be part
2948         // of the collection set!).
2949         _allocator->release_mutator_alloc_region();
2950 
2951         // This timing is only used by the ergonomics to handle our pause target.
2952         // It is unclear why this should not include the full pause. We will
2953         // investigate this in CR 7178365.
2954         //
2955         // Preserving the old comment here if that helps the investigation:
2956         //
2957         // The elapsed time induced by the start time below deliberately elides
2958         // the possible verification above.
2959         double sample_start_time_sec = os::elapsedTime();
2960 
2961         g1_policy()->record_collection_pause_start(sample_start_time_sec);
2962 
2963         if (collector_state()->in_initial_mark_gc()) {
2964           concurrent_mark()->pre_initial_mark();
2965         }
2966 
2967         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2968 
2969         evacuation_info.set_collectionset_regions(collection_set()->region_length());
2970 
2971         // Make sure the remembered sets are up to date. This needs to be
2972         // done before register_humongous_regions_with_cset(), because the
2973         // remembered sets are used there to choose eager reclaim candidates.
2974         // If the remembered sets are not up to date we might miss some
2975         // entries that need to be handled.
2976         g1_rem_set()->cleanupHRRS();
2977 
2978         register_humongous_regions_with_cset();
2979 
2980         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2981 
2982         // We call this after finalize_cset() to
2983         // ensure that the CSet has been finalized.
2984         _cm->verify_no_cset_oops();
2985 
2986         if (_hr_printer.is_active()) {
2987           G1PrintCollectionSetClosure cl(&_hr_printer);
2988           _collection_set.iterate(&cl);
2989         }
2990 
2991         // Initialize the GC alloc regions.
2992         _allocator->init_gc_alloc_regions(evacuation_info);
2993 
2994         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2995         pre_evacuate_collection_set();
2996 
2997         // Actually do the work...
2998         evacuate_collection_set(&per_thread_states);
2999 
3000         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3001 
3002         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3003         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3004 
3005         eagerly_reclaim_humongous_regions();
3006 
3007         record_obj_copy_mem_stats();
3008         _survivor_evac_stats.adjust_desired_plab_sz();
3009         _old_evac_stats.adjust_desired_plab_sz();
3010 
3011         double start = os::elapsedTime();
3012         start_new_collection_set();
3013         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3014 
3015         if (evacuation_failed()) {
3016           set_used(recalculate_used());
3017           if (_archive_allocator != NULL) {
3018             _archive_allocator->clear_used();
3019           }
3020           for (uint i = 0; i < ParallelGCThreads; i++) {
3021             if (_evacuation_failed_info_array[i].has_failed()) {
3022               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3023             }
3024           }
3025         } else {
3026           // The "used" of the the collection set have already been subtracted
3027           // when they were freed.  Add in the bytes evacuated.
3028           increase_used(g1_policy()->bytes_copied_during_gc());
3029         }
3030 
3031         if (collector_state()->in_initial_mark_gc()) {
3032           // We have to do this before we notify the CM threads that
3033           // they can start working to make sure that all the
3034           // appropriate initialization is done on the CM object.
3035           concurrent_mark()->post_initial_mark();
3036           // Note that we don't actually trigger the CM thread at
3037           // this point. We do that later when we're sure that
3038           // the current thread has completed its logging output.
3039         }
3040 
3041         allocate_dummy_regions();
3042 
3043         _allocator->init_mutator_alloc_region();
3044 
3045         {
3046           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3047           if (expand_bytes > 0) {
3048             size_t bytes_before = capacity();
3049             // No need for an ergo logging here,
3050             // expansion_amount() does this when it returns a value > 0.
3051             double expand_ms;
3052             if (!expand(expand_bytes, _workers, &expand_ms)) {
3053               // We failed to expand the heap. Cannot do anything about it.
3054             }
3055             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3056           }
3057         }
3058 
3059         // We redo the verification but now wrt to the new CSet which
3060         // has just got initialized after the previous CSet was freed.
3061         _cm->verify_no_cset_oops();
3062 
3063         // This timing is only used by the ergonomics to handle our pause target.
3064         // It is unclear why this should not include the full pause. We will
3065         // investigate this in CR 7178365.
3066         double sample_end_time_sec = os::elapsedTime();
3067         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3068         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3069         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3070 
3071         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3072         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3073 
3074         if (VerifyRememberedSets) {
3075           log_info(gc, verify)("[Verifying RemSets after GC]");
3076           VerifyRegionRemSetClosure v_cl;
3077           heap_region_iterate(&v_cl);
3078         }
3079 
3080         _verifier->verify_after_gc(verify_type);
3081         _verifier->check_bitmaps("GC End");
3082 
3083         assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3084         _ref_processor_stw->verify_no_references_recorded();
3085 
3086         // CM reference discovery will be re-enabled if necessary.
3087       }
3088 
3089 #ifdef TRACESPINNING
3090       ParallelTaskTerminator::print_termination_counts();
3091 #endif
3092 
3093       gc_epilogue(false);
3094     }
3095 
3096     // Print the remainder of the GC log output.
3097     if (evacuation_failed()) {
3098       log_info(gc)("To-space exhausted");
3099     }
3100 
3101     g1_policy()->print_phases();
3102     heap_transition.print();
3103 
3104     // It is not yet to safe to tell the concurrent mark to
3105     // start as we have some optional output below. We don't want the
3106     // output from the concurrent mark thread interfering with this
3107     // logging output either.
3108 
3109     _hrm.verify_optional();
3110     _verifier->verify_region_sets_optional();
3111 
3112     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3113     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3114 
3115     print_heap_after_gc();
3116     print_heap_regions();
3117     trace_heap_after_gc(_gc_tracer_stw);
3118 
3119     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3120     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3121     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3122     // before any GC notifications are raised.
3123     g1mm()->update_sizes();
3124 
3125     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3126     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3127     _gc_timer_stw->register_gc_end();
3128     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3129   }
3130   // It should now be safe to tell the concurrent mark thread to start
3131   // without its logging output interfering with the logging output
3132   // that came from the pause.
3133 
3134   if (should_start_conc_mark) {
3135     // CAUTION: after the doConcurrentMark() call below,
3136     // the concurrent marking thread(s) could be running
3137     // concurrently with us. Make sure that anything after
3138     // this point does not assume that we are the only GC thread
3139     // running. Note: of course, the actual marking work will
3140     // not start until the safepoint itself is released in
3141     // SuspendibleThreadSet::desynchronize().
3142     do_concurrent_mark();
3143   }
3144 
3145   return true;
3146 }
3147 
3148 void G1CollectedHeap::remove_self_forwarding_pointers() {
3149   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3150   workers()->run_task(&rsfp_task);
3151 }
3152 
3153 void G1CollectedHeap::restore_after_evac_failure() {
3154   double remove_self_forwards_start = os::elapsedTime();
3155 
3156   remove_self_forwarding_pointers();
3157   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3158   _preserved_marks_set.restore(&task_executor);
3159 
3160   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3161 }
3162 
3163 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3164   if (!_evacuation_failed) {
3165     _evacuation_failed = true;
3166   }
3167 
3168   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3169   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3170 }
3171 
3172 bool G1ParEvacuateFollowersClosure::offer_termination() {
3173   G1ParScanThreadState* const pss = par_scan_state();
3174   start_term_time();
3175   const bool res = terminator()->offer_termination();
3176   end_term_time();
3177   return res;
3178 }
3179 
3180 void G1ParEvacuateFollowersClosure::do_void() {
3181   G1ParScanThreadState* const pss = par_scan_state();
3182   pss->trim_queue();
3183   do {
3184     pss->steal_and_trim_queue(queues());
3185   } while (!offer_termination());
3186 }
3187 
3188 class G1ParTask : public AbstractGangTask {
3189 protected:
3190   G1CollectedHeap*         _g1h;
3191   G1ParScanThreadStateSet* _pss;
3192   RefToScanQueueSet*       _queues;
3193   G1RootProcessor*         _root_processor;
3194   ParallelTaskTerminator   _terminator;
3195   uint                     _n_workers;
3196 
3197 public:
3198   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3199     : AbstractGangTask("G1 collection"),
3200       _g1h(g1h),
3201       _pss(per_thread_states),
3202       _queues(task_queues),
3203       _root_processor(root_processor),
3204       _terminator(n_workers, _queues),
3205       _n_workers(n_workers)
3206   {}
3207 
3208   void work(uint worker_id) {
3209     if (worker_id >= _n_workers) return;  // no work needed this round
3210 
3211     double start_sec = os::elapsedTime();
3212     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3213 
3214     {
3215       ResourceMark rm;
3216       HandleMark   hm;
3217 
3218       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3219 
3220       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3221       pss->set_ref_discoverer(rp);
3222 
3223       double start_strong_roots_sec = os::elapsedTime();
3224 
3225       _root_processor->evacuate_roots(pss, worker_id);
3226 
3227       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3228       // treating the nmethods visited to act as roots for concurrent marking.
3229       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3230       // objects copied by the current evacuation.
3231       _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3232 
3233       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3234 
3235       double term_sec = 0.0;
3236       size_t evac_term_attempts = 0;
3237       {
3238         double start = os::elapsedTime();
3239         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3240         evac.do_void();
3241 
3242         evac_term_attempts = evac.term_attempts();
3243         term_sec = evac.term_time();
3244         double elapsed_sec = os::elapsedTime() - start;
3245 
3246         G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3247         p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3248         p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3249         p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3250       }
3251 
3252       assert(pss->queue_is_empty(), "should be empty");
3253 
3254       if (log_is_enabled(Debug, gc, task, stats)) {
3255         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3256         size_t lab_waste;
3257         size_t lab_undo_waste;
3258         pss->waste(lab_waste, lab_undo_waste);
3259         _g1h->print_termination_stats(worker_id,
3260                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3261                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3262                                       term_sec * 1000.0,                          /* evac term time */
3263                                       evac_term_attempts,                         /* evac term attempts */
3264                                       lab_waste,                                  /* alloc buffer waste */
3265                                       lab_undo_waste                              /* undo waste */
3266                                       );
3267       }
3268 
3269       // Close the inner scope so that the ResourceMark and HandleMark
3270       // destructors are executed here and are included as part of the
3271       // "GC Worker Time".
3272     }
3273     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3274   }
3275 };
3276 
3277 void G1CollectedHeap::print_termination_stats_hdr() {
3278   log_debug(gc, task, stats)("GC Termination Stats");
3279   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3280   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3281   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3282 }
3283 
3284 void G1CollectedHeap::print_termination_stats(uint worker_id,
3285                                               double elapsed_ms,
3286                                               double strong_roots_ms,
3287                                               double term_ms,
3288                                               size_t term_attempts,
3289                                               size_t alloc_buffer_waste,
3290                                               size_t undo_waste) const {
3291   log_debug(gc, task, stats)
3292               ("%3d %9.2f %9.2f %6.2f "
3293                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3294                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3295                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3296                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3297                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3298                alloc_buffer_waste * HeapWordSize / K,
3299                undo_waste * HeapWordSize / K);
3300 }
3301 
3302 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3303                                         bool class_unloading_occurred) {
3304   uint n_workers = workers()->active_workers();
3305 
3306   G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3307   ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred);
3308   workers()->run_task(&g1_unlink_task);
3309 }
3310 
3311 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3312                                        bool process_strings,
3313                                        bool process_string_dedup) {
3314   if (!process_strings && !process_string_dedup) {
3315     // Nothing to clean.
3316     return;
3317   }
3318 
3319   G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3320   StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings);
3321   workers()->run_task(&g1_unlink_task);
3322 }
3323 
3324 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3325  private:
3326   DirtyCardQueueSet* _queue;
3327   G1CollectedHeap* _g1h;
3328  public:
3329   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3330     _queue(queue), _g1h(g1h) { }
3331 
3332   virtual void work(uint worker_id) {
3333     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3334     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3335 
3336     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3337     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3338 
3339     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3340   }
3341 };
3342 
3343 void G1CollectedHeap::redirty_logged_cards() {
3344   double redirty_logged_cards_start = os::elapsedTime();
3345 
3346   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3347   dirty_card_queue_set().reset_for_par_iteration();
3348   workers()->run_task(&redirty_task);
3349 
3350   DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3351   dcq.merge_bufferlists(&dirty_card_queue_set());
3352   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3353 
3354   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3355 }
3356 
3357 // Weak Reference Processing support
3358 
3359 bool G1STWIsAliveClosure::do_object_b(oop p) {
3360   // An object is reachable if it is outside the collection set,
3361   // or is inside and copied.
3362   return !_g1h->is_in_cset(p) || p->is_forwarded();
3363 }
3364 
3365 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3366   assert(obj != NULL, "must not be NULL");
3367   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3368   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3369   // may falsely indicate that this is not the case here: however the collection set only
3370   // contains old regions when concurrent mark is not running.
3371   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3372 }
3373 
3374 // Non Copying Keep Alive closure
3375 class G1KeepAliveClosure: public OopClosure {
3376   G1CollectedHeap*_g1h;
3377 public:
3378   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3379   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3380   void do_oop(oop* p) {
3381     oop obj = *p;
3382     assert(obj != NULL, "the caller should have filtered out NULL values");
3383 
3384     const InCSetState cset_state =_g1h->in_cset_state(obj);
3385     if (!cset_state.is_in_cset_or_humongous()) {
3386       return;
3387     }
3388     if (cset_state.is_in_cset()) {
3389       assert( obj->is_forwarded(), "invariant" );
3390       *p = obj->forwardee();
3391     } else {
3392       assert(!obj->is_forwarded(), "invariant" );
3393       assert(cset_state.is_humongous(),
3394              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3395      _g1h->set_humongous_is_live(obj);
3396     }
3397   }
3398 };
3399 
3400 // Copying Keep Alive closure - can be called from both
3401 // serial and parallel code as long as different worker
3402 // threads utilize different G1ParScanThreadState instances
3403 // and different queues.
3404 
3405 class G1CopyingKeepAliveClosure: public OopClosure {
3406   G1CollectedHeap*         _g1h;
3407   G1ParScanThreadState*    _par_scan_state;
3408 
3409 public:
3410   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3411                             G1ParScanThreadState* pss):
3412     _g1h(g1h),
3413     _par_scan_state(pss)
3414   {}
3415 
3416   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3417   virtual void do_oop(      oop* p) { do_oop_work(p); }
3418 
3419   template <class T> void do_oop_work(T* p) {
3420     oop obj = RawAccess<>::oop_load(p);
3421 
3422     if (_g1h->is_in_cset_or_humongous(obj)) {
3423       // If the referent object has been forwarded (either copied
3424       // to a new location or to itself in the event of an
3425       // evacuation failure) then we need to update the reference
3426       // field and, if both reference and referent are in the G1
3427       // heap, update the RSet for the referent.
3428       //
3429       // If the referent has not been forwarded then we have to keep
3430       // it alive by policy. Therefore we have copy the referent.
3431       //
3432       // When the queue is drained (after each phase of reference processing)
3433       // the object and it's followers will be copied, the reference field set
3434       // to point to the new location, and the RSet updated.
3435       _par_scan_state->push_on_queue(p);
3436     }
3437   }
3438 };
3439 
3440 // Serial drain queue closure. Called as the 'complete_gc'
3441 // closure for each discovered list in some of the
3442 // reference processing phases.
3443 
3444 class G1STWDrainQueueClosure: public VoidClosure {
3445 protected:
3446   G1CollectedHeap* _g1h;
3447   G1ParScanThreadState* _par_scan_state;
3448 
3449   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3450 
3451 public:
3452   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3453     _g1h(g1h),
3454     _par_scan_state(pss)
3455   { }
3456 
3457   void do_void() {
3458     G1ParScanThreadState* const pss = par_scan_state();
3459     pss->trim_queue();
3460   }
3461 };
3462 
3463 // Parallel Reference Processing closures
3464 
3465 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3466 // processing during G1 evacuation pauses.
3467 
3468 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3469 private:
3470   G1CollectedHeap*          _g1h;
3471   G1ParScanThreadStateSet*  _pss;
3472   RefToScanQueueSet*        _queues;
3473   WorkGang*                 _workers;
3474 
3475 public:
3476   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3477                            G1ParScanThreadStateSet* per_thread_states,
3478                            WorkGang* workers,
3479                            RefToScanQueueSet *task_queues) :
3480     _g1h(g1h),
3481     _pss(per_thread_states),
3482     _queues(task_queues),
3483     _workers(workers)
3484   {
3485     g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3486   }
3487 
3488   // Executes the given task using concurrent marking worker threads.
3489   virtual void execute(ProcessTask& task, uint ergo_workers);
3490 };
3491 
3492 // Gang task for possibly parallel reference processing
3493 
3494 class G1STWRefProcTaskProxy: public AbstractGangTask {
3495   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3496   ProcessTask&     _proc_task;
3497   G1CollectedHeap* _g1h;
3498   G1ParScanThreadStateSet* _pss;
3499   RefToScanQueueSet* _task_queues;
3500   ParallelTaskTerminator* _terminator;
3501 
3502 public:
3503   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3504                         G1CollectedHeap* g1h,
3505                         G1ParScanThreadStateSet* per_thread_states,
3506                         RefToScanQueueSet *task_queues,
3507                         ParallelTaskTerminator* terminator) :
3508     AbstractGangTask("Process reference objects in parallel"),
3509     _proc_task(proc_task),
3510     _g1h(g1h),
3511     _pss(per_thread_states),
3512     _task_queues(task_queues),
3513     _terminator(terminator)
3514   {}
3515 
3516   virtual void work(uint worker_id) {
3517     // The reference processing task executed by a single worker.
3518     ResourceMark rm;
3519     HandleMark   hm;
3520 
3521     G1STWIsAliveClosure is_alive(_g1h);
3522 
3523     G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3524     pss->set_ref_discoverer(NULL);
3525 
3526     // Keep alive closure.
3527     G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3528 
3529     // Complete GC closure
3530     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3531 
3532     // Call the reference processing task's work routine.
3533     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3534 
3535     // Note we cannot assert that the refs array is empty here as not all
3536     // of the processing tasks (specifically phase2 - pp2_work) execute
3537     // the complete_gc closure (which ordinarily would drain the queue) so
3538     // the queue may not be empty.
3539   }
3540 };
3541 
3542 // Driver routine for parallel reference processing.
3543 // Creates an instance of the ref processing gang
3544 // task and has the worker threads execute it.
3545 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3546   assert(_workers != NULL, "Need parallel worker threads.");
3547 
3548   assert(_workers->active_workers() >= ergo_workers,
3549          "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3550          ergo_workers, _workers->active_workers());
3551   ParallelTaskTerminator terminator(ergo_workers, _queues);
3552   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3553 
3554   _workers->run_task(&proc_task_proxy, ergo_workers);
3555 }
3556 
3557 // End of weak reference support closures
3558 
3559 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3560   double ref_proc_start = os::elapsedTime();
3561 
3562   ReferenceProcessor* rp = _ref_processor_stw;
3563   assert(rp->discovery_enabled(), "should have been enabled");
3564 
3565   // Closure to test whether a referent is alive.
3566   G1STWIsAliveClosure is_alive(this);
3567 
3568   // Even when parallel reference processing is enabled, the processing
3569   // of JNI refs is serial and performed serially by the current thread
3570   // rather than by a worker. The following PSS will be used for processing
3571   // JNI refs.
3572 
3573   // Use only a single queue for this PSS.
3574   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3575   pss->set_ref_discoverer(NULL);
3576   assert(pss->queue_is_empty(), "pre-condition");
3577 
3578   // Keep alive closure.
3579   G1CopyingKeepAliveClosure keep_alive(this, pss);
3580 
3581   // Serial Complete GC closure
3582   G1STWDrainQueueClosure drain_queue(this, pss);
3583 
3584   // Setup the soft refs policy...
3585   rp->setup_policy(false);
3586 
3587   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3588 
3589   ReferenceProcessorStats stats;
3590   if (!rp->processing_is_mt()) {
3591     // Serial reference processing...
3592     stats = rp->process_discovered_references(&is_alive,
3593                                               &keep_alive,
3594                                               &drain_queue,
3595                                               NULL,
3596                                               pt);
3597   } else {
3598     uint no_of_gc_workers = workers()->active_workers();
3599 
3600     // Parallel reference processing
3601     assert(no_of_gc_workers <= rp->max_num_queues(),
3602            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3603            no_of_gc_workers,  rp->max_num_queues());
3604 
3605     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3606     stats = rp->process_discovered_references(&is_alive,
3607                                               &keep_alive,
3608                                               &drain_queue,
3609                                               &par_task_executor,
3610                                               pt);
3611   }
3612 
3613   _gc_tracer_stw->report_gc_reference_stats(stats);
3614 
3615   // We have completed copying any necessary live referent objects.
3616   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3617 
3618   make_pending_list_reachable();
3619 
3620   rp->verify_no_references_recorded();
3621 
3622   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3623   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3624 }
3625 
3626 void G1CollectedHeap::make_pending_list_reachable() {
3627   if (collector_state()->in_initial_mark_gc()) {
3628     oop pll_head = Universe::reference_pending_list();
3629     if (pll_head != NULL) {
3630       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3631       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3632     }
3633   }
3634 }
3635 
3636 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3637   double merge_pss_time_start = os::elapsedTime();
3638   per_thread_states->flush();
3639   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3640 }
3641 
3642 void G1CollectedHeap::pre_evacuate_collection_set() {
3643   _expand_heap_after_alloc_failure = true;
3644   _evacuation_failed = false;
3645 
3646   // Disable the hot card cache.
3647   _hot_card_cache->reset_hot_cache_claimed_index();
3648   _hot_card_cache->set_use_cache(false);
3649 
3650   g1_rem_set()->prepare_for_oops_into_collection_set_do();
3651   _preserved_marks_set.assert_empty();
3652 
3653   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3654 
3655   // InitialMark needs claim bits to keep track of the marked-through CLDs.
3656   if (collector_state()->in_initial_mark_gc()) {
3657     double start_clear_claimed_marks = os::elapsedTime();
3658 
3659     ClassLoaderDataGraph::clear_claimed_marks();
3660 
3661     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3662     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3663   }
3664 }
3665 
3666 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3667   // Should G1EvacuationFailureALot be in effect for this GC?
3668   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3669 
3670   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3671 
3672   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3673 
3674   double start_par_time_sec = os::elapsedTime();
3675   double end_par_time_sec;
3676 
3677   {
3678     const uint n_workers = workers()->active_workers();
3679     G1RootProcessor root_processor(this, n_workers);
3680     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3681 
3682     print_termination_stats_hdr();
3683 
3684     workers()->run_task(&g1_par_task);
3685     end_par_time_sec = os::elapsedTime();
3686 
3687     // Closing the inner scope will execute the destructor
3688     // for the G1RootProcessor object. We record the current
3689     // elapsed time before closing the scope so that time
3690     // taken for the destructor is NOT included in the
3691     // reported parallel time.
3692   }
3693 
3694   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3695   phase_times->record_par_time(par_time_ms);
3696 
3697   double code_root_fixup_time_ms =
3698         (os::elapsedTime() - end_par_time_sec) * 1000.0;
3699   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
3700 }
3701 
3702 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3703   // Also cleans the card table from temporary duplicate detection information used
3704   // during UpdateRS/ScanRS.
3705   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
3706 
3707   // Process any discovered reference objects - we have
3708   // to do this _before_ we retire the GC alloc regions
3709   // as we may have to copy some 'reachable' referent
3710   // objects (and their reachable sub-graphs) that were
3711   // not copied during the pause.
3712   process_discovered_references(per_thread_states);
3713 
3714   // FIXME
3715   // CM's reference processing also cleans up the string table.
3716   // Should we do that here also? We could, but it is a serial operation
3717   // and could significantly increase the pause time.
3718 
3719   G1STWIsAliveClosure is_alive(this);
3720   G1KeepAliveClosure keep_alive(this);
3721 
3722   WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3723                               g1_policy()->phase_times()->weak_phase_times());
3724 
3725   if (G1StringDedup::is_enabled()) {
3726     double fixup_start = os::elapsedTime();
3727 
3728     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
3729 
3730     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
3731     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
3732   }
3733 
3734   if (evacuation_failed()) {
3735     restore_after_evac_failure();
3736 
3737     // Reset the G1EvacuationFailureALot counters and flags
3738     // Note: the values are reset only when an actual
3739     // evacuation failure occurs.
3740     NOT_PRODUCT(reset_evacuation_should_fail();)
3741   }
3742 
3743   _preserved_marks_set.assert_empty();
3744 
3745   _allocator->release_gc_alloc_regions(evacuation_info);
3746 
3747   merge_per_thread_state_info(per_thread_states);
3748 
3749   // Reset and re-enable the hot card cache.
3750   // Note the counts for the cards in the regions in the
3751   // collection set are reset when the collection set is freed.
3752   _hot_card_cache->reset_hot_cache();
3753   _hot_card_cache->set_use_cache(true);
3754 
3755   purge_code_root_memory();
3756 
3757   redirty_logged_cards();
3758 #if COMPILER2_OR_JVMCI
3759   double start = os::elapsedTime();
3760   DerivedPointerTable::update_pointers();
3761   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3762 #endif
3763   g1_policy()->print_age_table();
3764 }
3765 
3766 void G1CollectedHeap::record_obj_copy_mem_stats() {
3767   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3768 
3769   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3770                                                create_g1_evac_summary(&_old_evac_stats));
3771 }
3772 
3773 void G1CollectedHeap::free_region(HeapRegion* hr,
3774                                   FreeRegionList* free_list,
3775                                   bool skip_remset,
3776                                   bool skip_hot_card_cache,
3777                                   bool locked) {
3778   assert(!hr->is_free(), "the region should not be free");
3779   assert(!hr->is_empty(), "the region should not be empty");
3780   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
3781   assert(free_list != NULL, "pre-condition");
3782 
3783   if (G1VerifyBitmaps) {
3784     MemRegion mr(hr->bottom(), hr->end());
3785     concurrent_mark()->clear_range_in_prev_bitmap(mr);
3786   }
3787 
3788   // Clear the card counts for this region.
3789   // Note: we only need to do this if the region is not young
3790   // (since we don't refine cards in young regions).
3791   if (!skip_hot_card_cache && !hr->is_young()) {
3792     _hot_card_cache->reset_card_counts(hr);
3793   }
3794   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3795   _g1_policy->remset_tracker()->update_at_free(hr);
3796   free_list->add_ordered(hr);
3797 }
3798 
3799 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3800                                             FreeRegionList* free_list) {
3801   assert(hr->is_humongous(), "this is only for humongous regions");
3802   assert(free_list != NULL, "pre-condition");
3803   hr->clear_humongous();
3804   free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3805 }
3806 
3807 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3808                                            const uint humongous_regions_removed) {
3809   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3810     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3811     _old_set.bulk_remove(old_regions_removed);
3812     _humongous_set.bulk_remove(humongous_regions_removed);
3813   }
3814 
3815 }
3816 
3817 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3818   assert(list != NULL, "list can't be null");
3819   if (!list->is_empty()) {
3820     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3821     _hrm.insert_list_into_free_list(list);
3822   }
3823 }
3824 
3825 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3826   decrease_used(bytes);
3827 }
3828 
3829 class G1FreeCollectionSetTask : public AbstractGangTask {
3830 private:
3831 
3832   // Closure applied to all regions in the collection set to do work that needs to
3833   // be done serially in a single thread.
3834   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3835   private:
3836     EvacuationInfo* _evacuation_info;
3837     const size_t* _surviving_young_words;
3838 
3839     // Bytes used in successfully evacuated regions before the evacuation.
3840     size_t _before_used_bytes;
3841     // Bytes used in unsucessfully evacuated regions before the evacuation
3842     size_t _after_used_bytes;
3843 
3844     size_t _bytes_allocated_in_old_since_last_gc;
3845 
3846     size_t _failure_used_words;
3847     size_t _failure_waste_words;
3848 
3849     FreeRegionList _local_free_list;
3850   public:
3851     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3852       HeapRegionClosure(),
3853       _evacuation_info(evacuation_info),
3854       _surviving_young_words(surviving_young_words),
3855       _before_used_bytes(0),
3856       _after_used_bytes(0),
3857       _bytes_allocated_in_old_since_last_gc(0),
3858       _failure_used_words(0),
3859       _failure_waste_words(0),
3860       _local_free_list("Local Region List for CSet Freeing") {
3861     }
3862 
3863     virtual bool do_heap_region(HeapRegion* r) {
3864       G1CollectedHeap* g1h = G1CollectedHeap::heap();
3865 
3866       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3867       g1h->clear_in_cset(r);
3868 
3869       if (r->is_young()) {
3870         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
3871                "Young index %d is wrong for region %u of type %s with %u young regions",
3872                r->young_index_in_cset(),
3873                r->hrm_index(),
3874                r->get_type_str(),
3875                g1h->collection_set()->young_region_length());
3876         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
3877         r->record_surv_words_in_group(words_survived);
3878       }
3879 
3880       if (!r->evacuation_failed()) {
3881         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
3882         _before_used_bytes += r->used();
3883         g1h->free_region(r,
3884                          &_local_free_list,
3885                          true, /* skip_remset */
3886                          true, /* skip_hot_card_cache */
3887                          true  /* locked */);
3888       } else {
3889         r->uninstall_surv_rate_group();
3890         r->set_young_index_in_cset(-1);
3891         r->set_evacuation_failed(false);
3892         // When moving a young gen region to old gen, we "allocate" that whole region
3893         // there. This is in addition to any already evacuated objects. Notify the
3894         // policy about that.
3895         // Old gen regions do not cause an additional allocation: both the objects
3896         // still in the region and the ones already moved are accounted for elsewhere.
3897         if (r->is_young()) {
3898           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
3899         }
3900         // The region is now considered to be old.
3901         r->set_old();
3902         // Do some allocation statistics accounting. Regions that failed evacuation
3903         // are always made old, so there is no need to update anything in the young
3904         // gen statistics, but we need to update old gen statistics.
3905         size_t used_words = r->marked_bytes() / HeapWordSize;
3906 
3907         _failure_used_words += used_words;
3908         _failure_waste_words += HeapRegion::GrainWords - used_words;
3909 
3910         g1h->old_set_add(r);
3911         _after_used_bytes += r->used();
3912       }
3913       return false;
3914     }
3915 
3916     void complete_work() {
3917       G1CollectedHeap* g1h = G1CollectedHeap::heap();
3918 
3919       _evacuation_info->set_regions_freed(_local_free_list.length());
3920       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
3921 
3922       g1h->prepend_to_freelist(&_local_free_list);
3923       g1h->decrement_summary_bytes(_before_used_bytes);
3924 
3925       G1Policy* policy = g1h->g1_policy();
3926       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
3927 
3928       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
3929     }
3930   };
3931 
3932   G1CollectionSet* _collection_set;
3933   G1SerialFreeCollectionSetClosure _cl;
3934   const size_t* _surviving_young_words;
3935 
3936   size_t _rs_lengths;
3937 
3938   volatile jint _serial_work_claim;
3939 
3940   struct WorkItem {
3941     uint region_idx;
3942     bool is_young;
3943     bool evacuation_failed;
3944 
3945     WorkItem(HeapRegion* r) {
3946       region_idx = r->hrm_index();
3947       is_young = r->is_young();
3948       evacuation_failed = r->evacuation_failed();
3949     }
3950   };
3951 
3952   volatile size_t _parallel_work_claim;
3953   size_t _num_work_items;
3954   WorkItem* _work_items;
3955 
3956   void do_serial_work() {
3957     // Need to grab the lock to be allowed to modify the old region list.
3958     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3959     _collection_set->iterate(&_cl);
3960   }
3961 
3962   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
3963     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3964 
3965     HeapRegion* r = g1h->region_at(region_idx);
3966     assert(!g1h->is_on_master_free_list(r), "sanity");
3967 
3968     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
3969 
3970     if (!is_young) {
3971       g1h->_hot_card_cache->reset_card_counts(r);
3972     }
3973 
3974     if (!evacuation_failed) {
3975       r->rem_set()->clear_locked();
3976     }
3977   }
3978 
3979   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
3980   private:
3981     size_t _cur_idx;
3982     WorkItem* _work_items;
3983   public:
3984     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
3985 
3986     virtual bool do_heap_region(HeapRegion* r) {
3987       _work_items[_cur_idx++] = WorkItem(r);
3988       return false;
3989     }
3990   };
3991 
3992   void prepare_work() {
3993     G1PrepareFreeCollectionSetClosure cl(_work_items);
3994     _collection_set->iterate(&cl);
3995   }
3996 
3997   void complete_work() {
3998     _cl.complete_work();
3999 
4000     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4001     policy->record_max_rs_lengths(_rs_lengths);
4002     policy->cset_regions_freed();
4003   }
4004 public:
4005   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4006     AbstractGangTask("G1 Free Collection Set"),
4007     _collection_set(collection_set),
4008     _cl(evacuation_info, surviving_young_words),
4009     _surviving_young_words(surviving_young_words),
4010     _rs_lengths(0),
4011     _serial_work_claim(0),
4012     _parallel_work_claim(0),
4013     _num_work_items(collection_set->region_length()),
4014     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4015     prepare_work();
4016   }
4017 
4018   ~G1FreeCollectionSetTask() {
4019     complete_work();
4020     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4021   }
4022 
4023   // Chunk size for work distribution. The chosen value has been determined experimentally
4024   // to be a good tradeoff between overhead and achievable parallelism.
4025   static uint chunk_size() { return 32; }
4026 
4027   virtual void work(uint worker_id) {
4028     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4029 
4030     // Claim serial work.
4031     if (_serial_work_claim == 0) {
4032       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4033       if (value == 0) {
4034         double serial_time = os::elapsedTime();
4035         do_serial_work();
4036         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4037       }
4038     }
4039 
4040     // Start parallel work.
4041     double young_time = 0.0;
4042     bool has_young_time = false;
4043     double non_young_time = 0.0;
4044     bool has_non_young_time = false;
4045 
4046     while (true) {
4047       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4048       size_t cur = end - chunk_size();
4049 
4050       if (cur >= _num_work_items) {
4051         break;
4052       }
4053 
4054       double start_time = os::elapsedTime();
4055 
4056       end = MIN2(end, _num_work_items);
4057 
4058       for (; cur < end; cur++) {
4059         bool is_young = _work_items[cur].is_young;
4060 
4061         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4062 
4063         double end_time = os::elapsedTime();
4064         double time_taken = end_time - start_time;
4065         if (is_young) {
4066           young_time += time_taken;
4067           has_young_time = true;
4068         } else {
4069           non_young_time += time_taken;
4070           has_non_young_time = true;
4071         }
4072         start_time = end_time;
4073       }
4074     }
4075 
4076     if (has_young_time) {
4077       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4078     }
4079     if (has_non_young_time) {
4080       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4081     }
4082   }
4083 };
4084 
4085 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4086   _eden.clear();
4087 
4088   double free_cset_start_time = os::elapsedTime();
4089 
4090   {
4091     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4092     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4093 
4094     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4095 
4096     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4097                         cl.name(),
4098                         num_workers,
4099                         _collection_set.region_length());
4100     workers()->run_task(&cl, num_workers);
4101   }
4102   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4103 
4104   collection_set->clear();
4105 }
4106 
4107 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4108  private:
4109   FreeRegionList* _free_region_list;
4110   HeapRegionSet* _proxy_set;
4111   uint _humongous_objects_reclaimed;
4112   uint _humongous_regions_reclaimed;
4113   size_t _freed_bytes;
4114  public:
4115 
4116   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4117     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4118   }
4119 
4120   virtual bool do_heap_region(HeapRegion* r) {
4121     if (!r->is_starts_humongous()) {
4122       return false;
4123     }
4124 
4125     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4126 
4127     oop obj = (oop)r->bottom();
4128     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4129 
4130     // The following checks whether the humongous object is live are sufficient.
4131     // The main additional check (in addition to having a reference from the roots
4132     // or the young gen) is whether the humongous object has a remembered set entry.
4133     //
4134     // A humongous object cannot be live if there is no remembered set for it
4135     // because:
4136     // - there can be no references from within humongous starts regions referencing
4137     // the object because we never allocate other objects into them.
4138     // (I.e. there are no intra-region references that may be missed by the
4139     // remembered set)
4140     // - as soon there is a remembered set entry to the humongous starts region
4141     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4142     // until the end of a concurrent mark.
4143     //
4144     // It is not required to check whether the object has been found dead by marking
4145     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4146     // all objects allocated during that time are considered live.
4147     // SATB marking is even more conservative than the remembered set.
4148     // So if at this point in the collection there is no remembered set entry,
4149     // nobody has a reference to it.
4150     // At the start of collection we flush all refinement logs, and remembered sets
4151     // are completely up-to-date wrt to references to the humongous object.
4152     //
4153     // Other implementation considerations:
4154     // - never consider object arrays at this time because they would pose
4155     // considerable effort for cleaning up the the remembered sets. This is
4156     // required because stale remembered sets might reference locations that
4157     // are currently allocated into.
4158     uint region_idx = r->hrm_index();
4159     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4160         !r->rem_set()->is_empty()) {
4161       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",
4162                                region_idx,
4163                                (size_t)obj->size() * HeapWordSize,
4164                                p2i(r->bottom()),
4165                                r->rem_set()->occupied(),
4166                                r->rem_set()->strong_code_roots_list_length(),
4167                                next_bitmap->is_marked(r->bottom()),
4168                                g1h->is_humongous_reclaim_candidate(region_idx),
4169                                obj->is_typeArray()
4170                               );
4171       return false;
4172     }
4173 
4174     guarantee(obj->is_typeArray(),
4175               "Only eagerly reclaiming type arrays is supported, but the object "
4176               PTR_FORMAT " is not.", p2i(r->bottom()));
4177 
4178     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",
4179                              region_idx,
4180                              (size_t)obj->size() * HeapWordSize,
4181                              p2i(r->bottom()),
4182                              r->rem_set()->occupied(),
4183                              r->rem_set()->strong_code_roots_list_length(),
4184                              next_bitmap->is_marked(r->bottom()),
4185                              g1h->is_humongous_reclaim_candidate(region_idx),
4186                              obj->is_typeArray()
4187                             );
4188 
4189     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4190     cm->humongous_object_eagerly_reclaimed(r);
4191     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4192            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4193            region_idx,
4194            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4195            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4196     _humongous_objects_reclaimed++;
4197     do {
4198       HeapRegion* next = g1h->next_region_in_humongous(r);
4199       _freed_bytes += r->used();
4200       r->set_containing_set(NULL);
4201       _humongous_regions_reclaimed++;
4202       g1h->free_humongous_region(r, _free_region_list);
4203       r = next;
4204     } while (r != NULL);
4205 
4206     return false;
4207   }
4208 
4209   uint humongous_objects_reclaimed() {
4210     return _humongous_objects_reclaimed;
4211   }
4212 
4213   uint humongous_regions_reclaimed() {
4214     return _humongous_regions_reclaimed;
4215   }
4216 
4217   size_t bytes_freed() const {
4218     return _freed_bytes;
4219   }
4220 };
4221 
4222 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4223   assert_at_safepoint_on_vm_thread();
4224 
4225   if (!G1EagerReclaimHumongousObjects ||
4226       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4227     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4228     return;
4229   }
4230 
4231   double start_time = os::elapsedTime();
4232 
4233   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4234 
4235   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4236   heap_region_iterate(&cl);
4237 
4238   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4239 
4240   G1HRPrinter* hrp = hr_printer();
4241   if (hrp->is_active()) {
4242     FreeRegionListIterator iter(&local_cleanup_list);
4243     while (iter.more_available()) {
4244       HeapRegion* hr = iter.get_next();
4245       hrp->cleanup(hr);
4246     }
4247   }
4248 
4249   prepend_to_freelist(&local_cleanup_list);
4250   decrement_summary_bytes(cl.bytes_freed());
4251 
4252   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4253                                                                     cl.humongous_objects_reclaimed());
4254 }
4255 
4256 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4257 public:
4258   virtual bool do_heap_region(HeapRegion* r) {
4259     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4260     G1CollectedHeap::heap()->clear_in_cset(r);
4261     r->set_young_index_in_cset(-1);
4262     return false;
4263   }
4264 };
4265 
4266 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4267   G1AbandonCollectionSetClosure cl;
4268   collection_set->iterate(&cl);
4269 
4270   collection_set->clear();
4271   collection_set->stop_incremental_building();
4272 }
4273 
4274 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4275   return _allocator->is_retained_old_region(hr);
4276 }
4277 
4278 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4279   _eden.add(hr);
4280   _g1_policy->set_region_eden(hr);
4281 }
4282 
4283 #ifdef ASSERT
4284 
4285 class NoYoungRegionsClosure: public HeapRegionClosure {
4286 private:
4287   bool _success;
4288 public:
4289   NoYoungRegionsClosure() : _success(true) { }
4290   bool do_heap_region(HeapRegion* r) {
4291     if (r->is_young()) {
4292       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4293                             p2i(r->bottom()), p2i(r->end()));
4294       _success = false;
4295     }
4296     return false;
4297   }
4298   bool success() { return _success; }
4299 };
4300 
4301 bool G1CollectedHeap::check_young_list_empty() {
4302   bool ret = (young_regions_count() == 0);
4303 
4304   NoYoungRegionsClosure closure;
4305   heap_region_iterate(&closure);
4306   ret = ret && closure.success();
4307 
4308   return ret;
4309 }
4310 
4311 #endif // ASSERT
4312 
4313 class TearDownRegionSetsClosure : public HeapRegionClosure {
4314   HeapRegionSet *_old_set;
4315 
4316 public:
4317   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4318 
4319   bool do_heap_region(HeapRegion* r) {
4320     if (r->is_old()) {
4321       _old_set->remove(r);
4322     } else if(r->is_young()) {
4323       r->uninstall_surv_rate_group();
4324     } else {
4325       // We ignore free regions, we'll empty the free list afterwards.
4326       // We ignore humongous and archive regions, we're not tearing down these
4327       // sets.
4328       assert(r->is_archive() || r->is_free() || r->is_humongous(),
4329              "it cannot be another type");
4330     }
4331     return false;
4332   }
4333 
4334   ~TearDownRegionSetsClosure() {
4335     assert(_old_set->is_empty(), "post-condition");
4336   }
4337 };
4338 
4339 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4340   assert_at_safepoint_on_vm_thread();
4341 
4342   if (!free_list_only) {
4343     TearDownRegionSetsClosure cl(&_old_set);
4344     heap_region_iterate(&cl);
4345 
4346     // Note that emptying the _young_list is postponed and instead done as
4347     // the first step when rebuilding the regions sets again. The reason for
4348     // this is that during a full GC string deduplication needs to know if
4349     // a collected region was young or old when the full GC was initiated.
4350   }
4351   _hrm.remove_all_free_regions();
4352 }
4353 
4354 void G1CollectedHeap::increase_used(size_t bytes) {
4355   _summary_bytes_used += bytes;
4356 }
4357 
4358 void G1CollectedHeap::decrease_used(size_t bytes) {
4359   assert(_summary_bytes_used >= bytes,
4360          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4361          _summary_bytes_used, bytes);
4362   _summary_bytes_used -= bytes;
4363 }
4364 
4365 void G1CollectedHeap::set_used(size_t bytes) {
4366   _summary_bytes_used = bytes;
4367 }
4368 
4369 class RebuildRegionSetsClosure : public HeapRegionClosure {
4370 private:
4371   bool _free_list_only;
4372 
4373   HeapRegionSet* _old_set;
4374   HeapRegionManager* _hrm;
4375 
4376   size_t _total_used;
4377 
4378 public:
4379   RebuildRegionSetsClosure(bool free_list_only,
4380                            HeapRegionSet* old_set,
4381                            HeapRegionManager* hrm) :
4382     _free_list_only(free_list_only),
4383     _old_set(old_set), _hrm(hrm), _total_used(0) {
4384     assert(_hrm->num_free_regions() == 0, "pre-condition");
4385     if (!free_list_only) {
4386       assert(_old_set->is_empty(), "pre-condition");
4387     }
4388   }
4389 
4390   bool do_heap_region(HeapRegion* r) {
4391     // After full GC, no region should have a remembered set.
4392     r->rem_set()->clear(true);
4393     if (r->is_empty()) {
4394       // Add free regions to the free list
4395       r->set_free();
4396       _hrm->insert_into_free_list(r);
4397     } else if (!_free_list_only) {
4398 
4399       if (r->is_archive() || r->is_humongous()) {
4400         // We ignore archive and humongous regions. We left these sets unchanged.
4401       } else {
4402         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4403         // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4404         r->move_to_old();
4405         _old_set->add(r);
4406       }
4407       _total_used += r->used();
4408     }
4409 
4410     return false;
4411   }
4412 
4413   size_t total_used() {
4414     return _total_used;
4415   }
4416 };
4417 
4418 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4419   assert_at_safepoint_on_vm_thread();
4420 
4421   if (!free_list_only) {
4422     _eden.clear();
4423     _survivor.clear();
4424   }
4425 
4426   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4427   heap_region_iterate(&cl);
4428 
4429   if (!free_list_only) {
4430     set_used(cl.total_used());
4431     if (_archive_allocator != NULL) {
4432       _archive_allocator->clear_used();
4433     }
4434   }
4435   assert(used_unlocked() == recalculate_used(),
4436          "inconsistent used_unlocked(), "
4437          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4438          used_unlocked(), recalculate_used());
4439 }
4440 
4441 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4442   HeapRegion* hr = heap_region_containing(p);
4443   return hr->is_in(p);
4444 }
4445 
4446 // Methods for the mutator alloc region
4447 
4448 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4449                                                       bool force) {
4450   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4451   bool should_allocate = g1_policy()->should_allocate_mutator_region();
4452   if (force || should_allocate) {
4453     HeapRegion* new_alloc_region = new_region(word_size,
4454                                               false /* is_old */,
4455                                               false /* do_expand */);
4456     if (new_alloc_region != NULL) {
4457       set_region_short_lived_locked(new_alloc_region);
4458       _hr_printer.alloc(new_alloc_region, !should_allocate);
4459       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4460       _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4461       return new_alloc_region;
4462     }
4463   }
4464   return NULL;
4465 }
4466 
4467 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4468                                                   size_t allocated_bytes) {
4469   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4470   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4471 
4472   collection_set()->add_eden_region(alloc_region);
4473   increase_used(allocated_bytes);
4474   _hr_printer.retire(alloc_region);
4475   // We update the eden sizes here, when the region is retired,
4476   // instead of when it's allocated, since this is the point that its
4477   // used space has been recorded in _summary_bytes_used.
4478   g1mm()->update_eden_size();
4479 }
4480 
4481 // Methods for the GC alloc regions
4482 
4483 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4484   if (dest.is_old()) {
4485     return true;
4486   } else {
4487     return survivor_regions_count() < g1_policy()->max_survivor_regions();
4488   }
4489 }
4490 
4491 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4492   assert(FreeList_lock->owned_by_self(), "pre-condition");
4493 
4494   if (!has_more_regions(dest)) {
4495     return NULL;
4496   }
4497 
4498   const bool is_survivor = dest.is_young();
4499 
4500   HeapRegion* new_alloc_region = new_region(word_size,
4501                                             !is_survivor,
4502                                             true /* do_expand */);
4503   if (new_alloc_region != NULL) {
4504     if (is_survivor) {
4505       new_alloc_region->set_survivor();
4506       _survivor.add(new_alloc_region);
4507       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4508     } else {
4509       new_alloc_region->set_old();
4510       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4511     }
4512     _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4513     _hr_printer.alloc(new_alloc_region);
4514     bool during_im = collector_state()->in_initial_mark_gc();
4515     new_alloc_region->note_start_of_copying(during_im);
4516     return new_alloc_region;
4517   }
4518   return NULL;
4519 }
4520 
4521 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4522                                              size_t allocated_bytes,
4523                                              InCSetState dest) {
4524   bool during_im = collector_state()->in_initial_mark_gc();
4525   alloc_region->note_end_of_copying(during_im);
4526   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4527   if (dest.is_old()) {
4528     old_set_add(alloc_region);
4529   }
4530   _hr_printer.retire(alloc_region);
4531 }
4532 
4533 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4534   bool expanded = false;
4535   uint index = _hrm.find_highest_free(&expanded);
4536 
4537   if (index != G1_NO_HRM_INDEX) {
4538     if (expanded) {
4539       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4540                                 HeapRegion::GrainWords * HeapWordSize);
4541     }
4542     _hrm.allocate_free_regions_starting_at(index, 1);
4543     return region_at(index);
4544   }
4545   return NULL;
4546 }
4547 
4548 // Optimized nmethod scanning
4549 
4550 class RegisterNMethodOopClosure: public OopClosure {
4551   G1CollectedHeap* _g1h;
4552   nmethod* _nm;
4553 
4554   template <class T> void do_oop_work(T* p) {
4555     T heap_oop = RawAccess<>::oop_load(p);
4556     if (!CompressedOops::is_null(heap_oop)) {
4557       oop obj = CompressedOops::decode_not_null(heap_oop);
4558       HeapRegion* hr = _g1h->heap_region_containing(obj);
4559       assert(!hr->is_continues_humongous(),
4560              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4561              " starting at " HR_FORMAT,
4562              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4563 
4564       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4565       hr->add_strong_code_root_locked(_nm);
4566     }
4567   }
4568 
4569 public:
4570   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4571     _g1h(g1h), _nm(nm) {}
4572 
4573   void do_oop(oop* p)       { do_oop_work(p); }
4574   void do_oop(narrowOop* p) { do_oop_work(p); }
4575 };
4576 
4577 class UnregisterNMethodOopClosure: public OopClosure {
4578   G1CollectedHeap* _g1h;
4579   nmethod* _nm;
4580 
4581   template <class T> void do_oop_work(T* p) {
4582     T heap_oop = RawAccess<>::oop_load(p);
4583     if (!CompressedOops::is_null(heap_oop)) {
4584       oop obj = CompressedOops::decode_not_null(heap_oop);
4585       HeapRegion* hr = _g1h->heap_region_containing(obj);
4586       assert(!hr->is_continues_humongous(),
4587              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4588              " starting at " HR_FORMAT,
4589              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4590 
4591       hr->remove_strong_code_root(_nm);
4592     }
4593   }
4594 
4595 public:
4596   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4597     _g1h(g1h), _nm(nm) {}
4598 
4599   void do_oop(oop* p)       { do_oop_work(p); }
4600   void do_oop(narrowOop* p) { do_oop_work(p); }
4601 };
4602 
4603 // Returns true if the reference points to an object that
4604 // can move in an incremental collection.
4605 bool G1CollectedHeap::is_scavengable(oop obj) {
4606   HeapRegion* hr = heap_region_containing(obj);
4607   return !hr->is_pinned();
4608 }
4609 
4610 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4611   guarantee(nm != NULL, "sanity");
4612   RegisterNMethodOopClosure reg_cl(this, nm);
4613   nm->oops_do(&reg_cl);
4614 }
4615 
4616 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4617   guarantee(nm != NULL, "sanity");
4618   UnregisterNMethodOopClosure reg_cl(this, nm);
4619   nm->oops_do(&reg_cl, true);
4620 }
4621 
4622 void G1CollectedHeap::purge_code_root_memory() {
4623   double purge_start = os::elapsedTime();
4624   G1CodeRootSet::purge();
4625   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4626   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4627 }
4628 
4629 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4630   G1CollectedHeap* _g1h;
4631 
4632 public:
4633   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4634     _g1h(g1h) {}
4635 
4636   void do_code_blob(CodeBlob* cb) {
4637     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4638     if (nm == NULL) {
4639       return;
4640     }
4641 
4642     if (ScavengeRootsInCode) {
4643       _g1h->register_nmethod(nm);
4644     }
4645   }
4646 };
4647 
4648 void G1CollectedHeap::rebuild_strong_code_roots() {
4649   RebuildStrongCodeRootClosure blob_cl(this);
4650   CodeCache::blobs_do(&blob_cl);
4651 }
4652 
4653 void G1CollectedHeap::initialize_serviceability() {
4654   _g1mm->initialize_serviceability();
4655 }
4656 
4657 MemoryUsage G1CollectedHeap::memory_usage() {
4658   return _g1mm->memory_usage();
4659 }
4660 
4661 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4662   return _g1mm->memory_managers();
4663 }
4664 
4665 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4666   return _g1mm->memory_pools();
4667 }