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 "classfile/symbolTable.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "gc/g1/g1Allocator.inline.hpp"
  32 #include "gc/g1/g1BarrierSet.hpp"
  33 #include "gc/g1/g1CollectedHeap.inline.hpp"
  34 #include "gc/g1/g1CollectionSet.hpp"
  35 #include "gc/g1/g1CollectorPolicy.hpp"
  36 #include "gc/g1/g1CollectorState.hpp"
  37 #include "gc/g1/g1ConcurrentRefine.hpp"
  38 #include "gc/g1/g1ConcurrentRefineThread.hpp"
  39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
  40 #include "gc/g1/g1EvacStats.inline.hpp"
  41 #include "gc/g1/g1FullCollector.hpp"
  42 #include "gc/g1/g1GCPhaseTimes.hpp"
  43 #include "gc/g1/g1HeapSizingPolicy.hpp"
  44 #include "gc/g1/g1HeapTransition.hpp"
  45 #include "gc/g1/g1HeapVerifier.hpp"
  46 #include "gc/g1/g1HotCardCache.hpp"
  47 #include "gc/g1/g1MemoryPool.hpp"
  48 #include "gc/g1/g1OopClosures.inline.hpp"
  49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  50 #include "gc/g1/g1Policy.hpp"
  51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  52 #include "gc/g1/g1RemSet.hpp"
  53 #include "gc/g1/g1RootClosures.hpp"
  54 #include "gc/g1/g1RootProcessor.hpp"
  55 #include "gc/g1/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/preservedMarks.inline.hpp"
  73 #include "gc/shared/suspendibleThreadSet.hpp"
  74 #include "gc/shared/referenceProcessor.inline.hpp"
  75 #include "gc/shared/taskqueue.inline.hpp"
  76 #include "gc/shared/weakProcessor.hpp"
  77 #include "logging/log.hpp"
  78 #include "memory/allocation.hpp"
  79 #include "memory/iterator.hpp"
  80 #include "memory/resourceArea.hpp"
  81 #include "oops/access.inline.hpp"
  82 #include "oops/compressedOops.inline.hpp"
  83 #include "oops/oop.inline.hpp"
  84 #include "prims/resolvedMethodTable.hpp"
  85 #include "runtime/atomic.hpp"
  86 #include "runtime/handles.inline.hpp"
  87 #include "runtime/init.hpp"
  88 #include "runtime/orderAccess.inline.hpp"
  89 #include "runtime/threadSMR.hpp"
  90 #include "runtime/vmThread.hpp"
  91 #include "utilities/align.hpp"
  92 #include "utilities/globalDefinitions.hpp"
  93 #include "utilities/stack.inline.hpp"
  94 
  95 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  96 
  97 // INVARIANTS/NOTES
  98 //
  99 // All allocation activity covered by the G1CollectedHeap interface is
 100 // serialized by acquiring the HeapLock.  This happens in mem_allocate
 101 // and allocate_new_tlab, which are the "entry" points to the
 102 // allocation code from the rest of the JVM.  (Note that this does not
 103 // apply to TLAB allocation, which is not part of this interface: it
 104 // is done by clients of this interface.)
 105 
 106 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 107  private:
 108   size_t _num_dirtied;
 109   G1CollectedHeap* _g1h;
 110   G1CardTable* _g1_ct;
 111 
 112   HeapRegion* region_for_card(jbyte* card_ptr) const {
 113     return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
 114   }
 115 
 116   bool will_become_free(HeapRegion* hr) const {
 117     // A region will be freed by free_collection_set if the region is in the
 118     // collection set and has not had an evacuation failure.
 119     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 120   }
 121 
 122  public:
 123   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 124     _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
 125 
 126   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 127     HeapRegion* hr = region_for_card(card_ptr);
 128 
 129     // Should only dirty cards in regions that won't be freed.
 130     if (!will_become_free(hr)) {
 131       *card_ptr = G1CardTable::dirty_card_val();
 132       _num_dirtied++;
 133     }
 134 
 135     return true;
 136   }
 137 
 138   size_t num_dirtied()   const { return _num_dirtied; }
 139 };
 140 
 141 
 142 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 143   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 144 }
 145 
 146 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 147   // The from card cache is not the memory that is actually committed. So we cannot
 148   // take advantage of the zero_filled parameter.
 149   reset_from_card_cache(start_idx, num_regions);
 150 }
 151 
 152 
 153 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 154                                              MemRegion mr) {
 155   return new HeapRegion(hrs_index, bot(), mr);
 156 }
 157 
 158 // Private methods.
 159 
 160 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 161   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 162          "the only time we use this to allocate a humongous region is "
 163          "when we are allocating a single humongous region");
 164 
 165   HeapRegion* res = _hrm.allocate_free_region(is_old);
 166 
 167   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 168     // Currently, only attempts to allocate GC alloc regions set
 169     // do_expand to true. So, we should only reach here during a
 170     // safepoint. If this assumption changes we might have to
 171     // reconsider the use of _expand_heap_after_alloc_failure.
 172     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 173 
 174     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 175                               word_size * HeapWordSize);
 176 
 177     if (expand(word_size * HeapWordSize)) {
 178       // Given that expand() succeeded in expanding the heap, and we
 179       // always expand the heap by an amount aligned to the heap
 180       // region size, the free list should in theory not be empty.
 181       // In either case allocate_free_region() will check for NULL.
 182       res = _hrm.allocate_free_region(is_old);
 183     } else {
 184       _expand_heap_after_alloc_failure = false;
 185     }
 186   }
 187   return res;
 188 }
 189 
 190 HeapWord*
 191 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 192                                                            uint num_regions,
 193                                                            size_t word_size) {
 194   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 195   assert(is_humongous(word_size), "word_size should be humongous");
 196   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 197 
 198   // Index of last region in the series.
 199   uint last = first + num_regions - 1;
 200 
 201   // We need to initialize the region(s) we just discovered. This is
 202   // a bit tricky given that it can happen concurrently with
 203   // refinement threads refining cards on these regions and
 204   // potentially wanting to refine the BOT as they are scanning
 205   // those cards (this can happen shortly after a cleanup; see CR
 206   // 6991377). So we have to set up the region(s) carefully and in
 207   // a specific order.
 208 
 209   // The word size sum of all the regions we will allocate.
 210   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 211   assert(word_size <= word_size_sum, "sanity");
 212 
 213   // This will be the "starts humongous" region.
 214   HeapRegion* first_hr = region_at(first);
 215   // The header of the new object will be placed at the bottom of
 216   // the first region.
 217   HeapWord* new_obj = first_hr->bottom();
 218   // This will be the new top of the new object.
 219   HeapWord* obj_top = new_obj + word_size;
 220 
 221   // First, we need to zero the header of the space that we will be
 222   // allocating. When we update top further down, some refinement
 223   // threads might try to scan the region. By zeroing the header we
 224   // ensure that any thread that will try to scan the region will
 225   // come across the zero klass word and bail out.
 226   //
 227   // NOTE: It would not have been correct to have used
 228   // CollectedHeap::fill_with_object() and make the space look like
 229   // an int array. The thread that is doing the allocation will
 230   // later update the object header to a potentially different array
 231   // type and, for a very short period of time, the klass and length
 232   // fields will be inconsistent. This could cause a refinement
 233   // thread to calculate the object size incorrectly.
 234   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 235 
 236   // Next, pad out the unused tail of the last region with filler
 237   // objects, for improved usage accounting.
 238   // How many words we use for filler objects.
 239   size_t word_fill_size = word_size_sum - word_size;
 240 
 241   // How many words memory we "waste" which cannot hold a filler object.
 242   size_t words_not_fillable = 0;
 243 
 244   if (word_fill_size >= min_fill_size()) {
 245     fill_with_objects(obj_top, word_fill_size);
 246   } else if (word_fill_size > 0) {
 247     // We have space to fill, but we cannot fit an object there.
 248     words_not_fillable = word_fill_size;
 249     word_fill_size = 0;
 250   }
 251 
 252   // We will set up the first region as "starts humongous". This
 253   // will also update the BOT covering all the regions to reflect
 254   // that there is a single object that starts at the bottom of the
 255   // first region.
 256   first_hr->set_starts_humongous(obj_top, word_fill_size);
 257   _g1_policy->remset_tracker()->update_at_allocate(first_hr);
 258   // Then, if there are any, we will set up the "continues
 259   // humongous" regions.
 260   HeapRegion* hr = NULL;
 261   for (uint i = first + 1; i <= last; ++i) {
 262     hr = region_at(i);
 263     hr->set_continues_humongous(first_hr);
 264     _g1_policy->remset_tracker()->update_at_allocate(hr);
 265   }
 266 
 267   // Up to this point no concurrent thread would have been able to
 268   // do any scanning on any region in this series. All the top
 269   // fields still point to bottom, so the intersection between
 270   // [bottom,top] and [card_start,card_end] will be empty. Before we
 271   // update the top fields, we'll do a storestore to make sure that
 272   // no thread sees the update to top before the zeroing of the
 273   // object header and the BOT initialization.
 274   OrderAccess::storestore();
 275 
 276   // Now, we will update the top fields of the "continues humongous"
 277   // regions except the last one.
 278   for (uint i = first; i < last; ++i) {
 279     hr = region_at(i);
 280     hr->set_top(hr->end());
 281   }
 282 
 283   hr = region_at(last);
 284   // If we cannot fit a filler object, we must set top to the end
 285   // of the humongous object, otherwise we cannot iterate the heap
 286   // and the BOT will not be complete.
 287   hr->set_top(hr->end() - words_not_fillable);
 288 
 289   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 290          "obj_top should be in last region");
 291 
 292   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 293 
 294   assert(words_not_fillable == 0 ||
 295          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 296          "Miscalculation in humongous allocation");
 297 
 298   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 299 
 300   for (uint i = first; i <= last; ++i) {
 301     hr = region_at(i);
 302     _humongous_set.add(hr);
 303     _hr_printer.alloc(hr);
 304   }
 305 
 306   return new_obj;
 307 }
 308 
 309 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 310   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 311   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 312 }
 313 
 314 // If could fit into free regions w/o expansion, try.
 315 // Otherwise, if can expand, do so.
 316 // Otherwise, if using ex regions might help, try with ex given back.
 317 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 318   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 319 
 320   _verifier->verify_region_sets_optional();
 321 
 322   uint first = G1_NO_HRM_INDEX;
 323   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 324 
 325   if (obj_regions == 1) {
 326     // Only one region to allocate, try to use a fast path by directly allocating
 327     // from the free lists. Do not try to expand here, we will potentially do that
 328     // later.
 329     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 330     if (hr != NULL) {
 331       first = hr->hrm_index();
 332     }
 333   } else {
 334     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 335     // are lucky enough to find some.
 336     first = _hrm.find_contiguous_only_empty(obj_regions);
 337     if (first != G1_NO_HRM_INDEX) {
 338       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 339     }
 340   }
 341 
 342   if (first == G1_NO_HRM_INDEX) {
 343     // Policy: We could not find enough regions for the humongous object in the
 344     // free list. Look through the heap to find a mix of free and uncommitted regions.
 345     // If so, try expansion.
 346     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 347     if (first != G1_NO_HRM_INDEX) {
 348       // We found something. Make sure these regions are committed, i.e. expand
 349       // the heap. Alternatively we could do a defragmentation GC.
 350       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 351                                     word_size * HeapWordSize);
 352 
 353       _hrm.expand_at(first, obj_regions, workers());
 354       g1_policy()->record_new_heap_size(num_regions());
 355 
 356 #ifdef ASSERT
 357       for (uint i = first; i < first + obj_regions; ++i) {
 358         HeapRegion* hr = region_at(i);
 359         assert(hr->is_free(), "sanity");
 360         assert(hr->is_empty(), "sanity");
 361         assert(is_on_master_free_list(hr), "sanity");
 362       }
 363 #endif
 364       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 365     } else {
 366       // Policy: Potentially trigger a defragmentation GC.
 367     }
 368   }
 369 
 370   HeapWord* result = NULL;
 371   if (first != G1_NO_HRM_INDEX) {
 372     result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
 373     assert(result != NULL, "it should always return a valid result");
 374 
 375     // A successful humongous object allocation changes the used space
 376     // information of the old generation so we need to recalculate the
 377     // sizes and update the jstat counters here.
 378     g1mm()->update_sizes();
 379   }
 380 
 381   _verifier->verify_region_sets_optional();
 382 
 383   return result;
 384 }
 385 
 386 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 387   assert_heap_not_locked_and_not_at_safepoint();
 388   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 389 
 390   return attempt_allocation(word_size);
 391 }
 392 
 393 HeapWord*
 394 G1CollectedHeap::mem_allocate(size_t word_size,
 395                               bool*  gc_overhead_limit_was_exceeded) {
 396   assert_heap_not_locked_and_not_at_safepoint();
 397 
 398   if (is_humongous(word_size)) {
 399     return attempt_allocation_humongous(word_size);
 400   }
 401   return attempt_allocation(word_size);
 402 }
 403 
 404 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
 405   ResourceMark rm; // For retrieving the thread names in log messages.
 406 
 407   // Make sure you read the note in attempt_allocation_humongous().
 408 
 409   assert_heap_not_locked_and_not_at_safepoint();
 410   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 411          "be called for humongous allocation requests");
 412 
 413   // We should only get here after the first-level allocation attempt
 414   // (attempt_allocation()) failed to allocate.
 415 
 416   // We will loop until a) we manage to successfully perform the
 417   // allocation or b) we successfully schedule a collection which
 418   // fails to perform the allocation. b) is the only case when we'll
 419   // return NULL.
 420   HeapWord* result = NULL;
 421   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 422     bool should_try_gc;
 423     uint gc_count_before;
 424 
 425     {
 426       MutexLockerEx x(Heap_lock);
 427       result = _allocator->attempt_allocation_locked(word_size);
 428       if (result != NULL) {
 429         return result;
 430       }
 431 
 432       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 433       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 434       // waiting because the GCLocker is active to not wait too long.
 435       if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
 436         // No need for an ergo message here, can_expand_young_list() does this when
 437         // it returns true.
 438         result = _allocator->attempt_allocation_force(word_size);
 439         if (result != NULL) {
 440           return result;
 441         }
 442       }
 443       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 444       // the GCLocker initiated GC has been performed and then retry. This includes
 445       // the case when the GC Locker is not active but has not been performed.
 446       should_try_gc = !GCLocker::needs_gc();
 447       // Read the GC count while still holding the Heap_lock.
 448       gc_count_before = total_collections();
 449     }
 450 
 451     if (should_try_gc) {
 452       bool succeeded;
 453       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 454                                    GCCause::_g1_inc_collection_pause);
 455       if (result != NULL) {
 456         assert(succeeded, "only way to get back a non-NULL result");
 457         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 458                              Thread::current()->name(), p2i(result));
 459         return result;
 460       }
 461 
 462       if (succeeded) {
 463         // We successfully scheduled a collection which failed to allocate. No
 464         // point in trying to allocate further. We'll just return NULL.
 465         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 466                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 467         return NULL;
 468       }
 469       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 470                            Thread::current()->name(), word_size);
 471     } else {
 472       // Failed to schedule a collection.
 473       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 474         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 475                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 476         return NULL;
 477       }
 478       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 479       // The GCLocker is either active or the GCLocker initiated
 480       // GC has not yet been performed. Stall until it is and
 481       // then retry the allocation.
 482       GCLocker::stall_until_clear();
 483       gclocker_retry_count += 1;
 484     }
 485 
 486     // We can reach here if we were unsuccessful in scheduling a
 487     // collection (because another thread beat us to it) or if we were
 488     // stalled due to the GC locker. In either can we should retry the
 489     // allocation attempt in case another thread successfully
 490     // performed a collection and reclaimed enough space. We do the
 491     // first attempt (without holding the Heap_lock) here and the
 492     // follow-on attempt will be at the start of the next loop
 493     // iteration (after taking the Heap_lock).
 494 
 495     result = _allocator->attempt_allocation(word_size);
 496     if (result != NULL) {
 497       return result;
 498     }
 499 
 500     // Give a warning if we seem to be looping forever.
 501     if ((QueuedAllocationWarningCount > 0) &&
 502         (try_count % QueuedAllocationWarningCount == 0)) {
 503       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 504                              Thread::current()->name(), try_count, word_size);
 505     }
 506   }
 507 
 508   ShouldNotReachHere();
 509   return NULL;
 510 }
 511 
 512 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 513   assert_at_safepoint_on_vm_thread();
 514   if (_archive_allocator == NULL) {
 515     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 516   }
 517 }
 518 
 519 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 520   // Allocations in archive regions cannot be of a size that would be considered
 521   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 522   // may be different at archive-restore time.
 523   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 524 }
 525 
 526 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 527   assert_at_safepoint_on_vm_thread();
 528   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 529   if (is_archive_alloc_too_large(word_size)) {
 530     return NULL;
 531   }
 532   return _archive_allocator->archive_mem_allocate(word_size);
 533 }
 534 
 535 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 536                                               size_t end_alignment_in_bytes) {
 537   assert_at_safepoint_on_vm_thread();
 538   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 539 
 540   // Call complete_archive to do the real work, filling in the MemRegion
 541   // array with the archive regions.
 542   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 543   delete _archive_allocator;
 544   _archive_allocator = NULL;
 545 }
 546 
 547 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 548   assert(ranges != NULL, "MemRegion array NULL");
 549   assert(count != 0, "No MemRegions provided");
 550   MemRegion reserved = _hrm.reserved();
 551   for (size_t i = 0; i < count; i++) {
 552     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 553       return false;
 554     }
 555   }
 556   return true;
 557 }
 558 
 559 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 560                                             size_t count,
 561                                             bool open) {
 562   assert(!is_init_completed(), "Expect to be called at JVM init time");
 563   assert(ranges != NULL, "MemRegion array NULL");
 564   assert(count != 0, "No MemRegions provided");
 565   MutexLockerEx x(Heap_lock);
 566 
 567   MemRegion reserved = _hrm.reserved();
 568   HeapWord* prev_last_addr = NULL;
 569   HeapRegion* prev_last_region = NULL;
 570 
 571   // Temporarily disable pretouching of heap pages. This interface is used
 572   // when mmap'ing archived heap data in, so pre-touching is wasted.
 573   FlagSetting fs(AlwaysPreTouch, false);
 574 
 575   // Enable archive object checking used by G1MarkSweep. We have to let it know
 576   // about each archive range, so that objects in those ranges aren't marked.
 577   G1ArchiveAllocator::enable_archive_object_check();
 578 
 579   // For each specified MemRegion range, allocate the corresponding G1
 580   // regions and mark them as archive regions. We expect the ranges
 581   // in ascending starting address order, without overlap.
 582   for (size_t i = 0; i < count; i++) {
 583     MemRegion curr_range = ranges[i];
 584     HeapWord* start_address = curr_range.start();
 585     size_t word_size = curr_range.word_size();
 586     HeapWord* last_address = curr_range.last();
 587     size_t commits = 0;
 588 
 589     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 590               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 591               p2i(start_address), p2i(last_address));
 592     guarantee(start_address > prev_last_addr,
 593               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 594               p2i(start_address), p2i(prev_last_addr));
 595     prev_last_addr = last_address;
 596 
 597     // Check for ranges that start in the same G1 region in which the previous
 598     // range ended, and adjust the start address so we don't try to allocate
 599     // the same region again. If the current range is entirely within that
 600     // region, skip it, just adjusting the recorded top.
 601     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 602     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 603       start_address = start_region->end();
 604       if (start_address > last_address) {
 605         increase_used(word_size * HeapWordSize);
 606         start_region->set_top(last_address + 1);
 607         continue;
 608       }
 609       start_region->set_top(start_address);
 610       curr_range = MemRegion(start_address, last_address + 1);
 611       start_region = _hrm.addr_to_region(start_address);
 612     }
 613 
 614     // Perform the actual region allocation, exiting if it fails.
 615     // Then note how much new space we have allocated.
 616     if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
 617       return false;
 618     }
 619     increase_used(word_size * HeapWordSize);
 620     if (commits != 0) {
 621       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 622                                 HeapRegion::GrainWords * HeapWordSize * commits);
 623 
 624     }
 625 
 626     // Mark each G1 region touched by the range as archive, add it to
 627     // the old set, and set top.
 628     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 629     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 630     prev_last_region = last_region;
 631 
 632     while (curr_region != NULL) {
 633       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 634              "Region already in use (index %u)", curr_region->hrm_index());
 635       if (open) {
 636         curr_region->set_open_archive();
 637       } else {
 638         curr_region->set_closed_archive();
 639       }
 640       _hr_printer.alloc(curr_region);
 641       _old_set.add(curr_region);
 642       HeapWord* top;
 643       HeapRegion* next_region;
 644       if (curr_region != last_region) {
 645         top = curr_region->end();
 646         next_region = _hrm.next_region_in_heap(curr_region);
 647       } else {
 648         top = last_address + 1;
 649         next_region = NULL;
 650       }
 651       curr_region->set_top(top);
 652       curr_region->set_first_dead(top);
 653       curr_region->set_end_of_live(top);
 654       curr_region = next_region;
 655     }
 656 
 657     // Notify mark-sweep of the archive
 658     G1ArchiveAllocator::set_range_archive(curr_range, open);
 659   }
 660   return true;
 661 }
 662 
 663 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 664   assert(!is_init_completed(), "Expect to be called at JVM init time");
 665   assert(ranges != NULL, "MemRegion array NULL");
 666   assert(count != 0, "No MemRegions provided");
 667   MemRegion reserved = _hrm.reserved();
 668   HeapWord *prev_last_addr = NULL;
 669   HeapRegion* prev_last_region = NULL;
 670 
 671   // For each MemRegion, create filler objects, if needed, in the G1 regions
 672   // that contain the address range. The address range actually within the
 673   // MemRegion will not be modified. That is assumed to have been initialized
 674   // elsewhere, probably via an mmap of archived heap data.
 675   MutexLockerEx x(Heap_lock);
 676   for (size_t i = 0; i < count; i++) {
 677     HeapWord* start_address = ranges[i].start();
 678     HeapWord* last_address = ranges[i].last();
 679 
 680     assert(reserved.contains(start_address) && reserved.contains(last_address),
 681            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 682            p2i(start_address), p2i(last_address));
 683     assert(start_address > prev_last_addr,
 684            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 685            p2i(start_address), p2i(prev_last_addr));
 686 
 687     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 688     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 689     HeapWord* bottom_address = start_region->bottom();
 690 
 691     // Check for a range beginning in the same region in which the
 692     // previous one ended.
 693     if (start_region == prev_last_region) {
 694       bottom_address = prev_last_addr + 1;
 695     }
 696 
 697     // Verify that the regions were all marked as archive regions by
 698     // alloc_archive_regions.
 699     HeapRegion* curr_region = start_region;
 700     while (curr_region != NULL) {
 701       guarantee(curr_region->is_archive(),
 702                 "Expected archive region at index %u", curr_region->hrm_index());
 703       if (curr_region != last_region) {
 704         curr_region = _hrm.next_region_in_heap(curr_region);
 705       } else {
 706         curr_region = NULL;
 707       }
 708     }
 709 
 710     prev_last_addr = last_address;
 711     prev_last_region = last_region;
 712 
 713     // Fill the memory below the allocated range with dummy object(s),
 714     // if the region bottom does not match the range start, or if the previous
 715     // range ended within the same G1 region, and there is a gap.
 716     if (start_address != bottom_address) {
 717       size_t fill_size = pointer_delta(start_address, bottom_address);
 718       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 719       increase_used(fill_size * HeapWordSize);
 720     }
 721   }
 722 }
 723 
 724 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) {
 725   assert_heap_not_locked_and_not_at_safepoint();
 726   assert(!is_humongous(word_size), "attempt_allocation() should not "
 727          "be called for humongous allocation requests");
 728 
 729   HeapWord* result = _allocator->attempt_allocation(word_size);
 730 
 731   if (result == NULL) {
 732     result = attempt_allocation_slow(word_size);
 733   }
 734   assert_heap_not_locked();
 735   if (result != NULL) {
 736     dirty_young_block(result, word_size);
 737   }
 738   return result;
 739 }
 740 
 741 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 742   assert(!is_init_completed(), "Expect to be called at JVM init time");
 743   assert(ranges != NULL, "MemRegion array NULL");
 744   assert(count != 0, "No MemRegions provided");
 745   MemRegion reserved = _hrm.reserved();
 746   HeapWord* prev_last_addr = NULL;
 747   HeapRegion* prev_last_region = NULL;
 748   size_t size_used = 0;
 749   size_t uncommitted_regions = 0;
 750 
 751   // For each Memregion, free the G1 regions that constitute it, and
 752   // notify mark-sweep that the range is no longer to be considered 'archive.'
 753   MutexLockerEx x(Heap_lock);
 754   for (size_t i = 0; i < count; i++) {
 755     HeapWord* start_address = ranges[i].start();
 756     HeapWord* last_address = ranges[i].last();
 757 
 758     assert(reserved.contains(start_address) && reserved.contains(last_address),
 759            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 760            p2i(start_address), p2i(last_address));
 761     assert(start_address > prev_last_addr,
 762            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 763            p2i(start_address), p2i(prev_last_addr));
 764     size_used += ranges[i].byte_size();
 765     prev_last_addr = last_address;
 766 
 767     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 768     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 769 
 770     // Check for ranges that start in the same G1 region in which the previous
 771     // range ended, and adjust the start address so we don't try to free
 772     // the same region again. If the current range is entirely within that
 773     // region, skip it.
 774     if (start_region == prev_last_region) {
 775       start_address = start_region->end();
 776       if (start_address > last_address) {
 777         continue;
 778       }
 779       start_region = _hrm.addr_to_region(start_address);
 780     }
 781     prev_last_region = last_region;
 782 
 783     // After verifying that each region was marked as an archive region by
 784     // alloc_archive_regions, set it free and empty and uncommit it.
 785     HeapRegion* curr_region = start_region;
 786     while (curr_region != NULL) {
 787       guarantee(curr_region->is_archive(),
 788                 "Expected archive region at index %u", curr_region->hrm_index());
 789       uint curr_index = curr_region->hrm_index();
 790       _old_set.remove(curr_region);
 791       curr_region->set_free();
 792       curr_region->set_top(curr_region->bottom());
 793       if (curr_region != last_region) {
 794         curr_region = _hrm.next_region_in_heap(curr_region);
 795       } else {
 796         curr_region = NULL;
 797       }
 798       _hrm.shrink_at(curr_index, 1);
 799       uncommitted_regions++;
 800     }
 801 
 802     // Notify mark-sweep that this is no longer an archive range.
 803     G1ArchiveAllocator::set_range_archive(ranges[i], false);
 804   }
 805 
 806   if (uncommitted_regions != 0) {
 807     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 808                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 809   }
 810   decrease_used(size_used);
 811 }
 812 
 813 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 814   ResourceMark rm; // For retrieving the thread names in log messages.
 815 
 816   // The structure of this method has a lot of similarities to
 817   // attempt_allocation_slow(). The reason these two were not merged
 818   // into a single one is that such a method would require several "if
 819   // allocation is not humongous do this, otherwise do that"
 820   // conditional paths which would obscure its flow. In fact, an early
 821   // version of this code did use a unified method which was harder to
 822   // follow and, as a result, it had subtle bugs that were hard to
 823   // track down. So keeping these two methods separate allows each to
 824   // be more readable. It will be good to keep these two in sync as
 825   // much as possible.
 826 
 827   assert_heap_not_locked_and_not_at_safepoint();
 828   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 829          "should only be called for humongous allocations");
 830 
 831   // Humongous objects can exhaust the heap quickly, so we should check if we
 832   // need to start a marking cycle at each humongous object allocation. We do
 833   // the check before we do the actual allocation. The reason for doing it
 834   // before the allocation is that we avoid having to keep track of the newly
 835   // allocated memory while we do a GC.
 836   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 837                                            word_size)) {
 838     collect(GCCause::_g1_humongous_allocation);
 839   }
 840 
 841   // We will loop until a) we manage to successfully perform the
 842   // allocation or b) we successfully schedule a collection which
 843   // fails to perform the allocation. b) is the only case when we'll
 844   // return NULL.
 845   HeapWord* result = NULL;
 846   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 847     bool should_try_gc;
 848     uint gc_count_before;
 849 
 850 
 851     {
 852       MutexLockerEx x(Heap_lock);
 853 
 854       // Given that humongous objects are not allocated in young
 855       // regions, we'll first try to do the allocation without doing a
 856       // collection hoping that there's enough space in the heap.
 857       result = humongous_obj_allocate(word_size);
 858       if (result != NULL) {
 859         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 860         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 861         return result;
 862       }
 863 
 864       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 865       // the GCLocker initiated GC has been performed and then retry. This includes
 866       // the case when the GC Locker is not active but has not been performed.
 867       should_try_gc = !GCLocker::needs_gc();
 868       // Read the GC count while still holding the Heap_lock.
 869       gc_count_before = total_collections();
 870     }
 871 
 872     if (should_try_gc) {
 873       bool succeeded;
 874       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 875                                    GCCause::_g1_humongous_allocation);
 876       if (result != NULL) {
 877         assert(succeeded, "only way to get back a non-NULL result");
 878         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 879                              Thread::current()->name(), p2i(result));
 880         return result;
 881       }
 882 
 883       if (succeeded) {
 884         // We successfully scheduled a collection which failed to allocate. No
 885         // point in trying to allocate further. We'll just return NULL.
 886         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 887                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 888         return NULL;
 889       }
 890       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 891                            Thread::current()->name(), word_size);
 892     } else {
 893       // Failed to schedule a collection.
 894       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 895         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 896                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 897         return NULL;
 898       }
 899       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 900       // The GCLocker is either active or the GCLocker initiated
 901       // GC has not yet been performed. Stall until it is and
 902       // then retry the allocation.
 903       GCLocker::stall_until_clear();
 904       gclocker_retry_count += 1;
 905     }
 906 
 907 
 908     // We can reach here if we were unsuccessful in scheduling a
 909     // collection (because another thread beat us to it) or if we were
 910     // stalled due to the GC locker. In either can we should retry the
 911     // allocation attempt in case another thread successfully
 912     // performed a collection and reclaimed enough space.
 913     // Humongous object allocation always needs a lock, so we wait for the retry
 914     // in the next iteration of the loop, unlike for the regular iteration case.
 915     // Give a warning if we seem to be looping forever.
 916 
 917     if ((QueuedAllocationWarningCount > 0) &&
 918         (try_count % QueuedAllocationWarningCount == 0)) {
 919       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 920                              Thread::current()->name(), try_count, word_size);
 921     }
 922   }
 923 
 924   ShouldNotReachHere();
 925   return NULL;
 926 }
 927 
 928 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 929                                                            bool expect_null_mutator_alloc_region) {
 930   assert_at_safepoint_on_vm_thread();
 931   assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
 932          "the current alloc region was unexpectedly found to be non-NULL");
 933 
 934   if (!is_humongous(word_size)) {
 935     return _allocator->attempt_allocation_locked(word_size);
 936   } else {
 937     HeapWord* result = humongous_obj_allocate(word_size);
 938     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
 939       collector_state()->set_initiate_conc_mark_if_possible(true);
 940     }
 941     return result;
 942   }
 943 
 944   ShouldNotReachHere();
 945 }
 946 
 947 class PostCompactionPrinterClosure: public HeapRegionClosure {
 948 private:
 949   G1HRPrinter* _hr_printer;
 950 public:
 951   bool do_heap_region(HeapRegion* hr) {
 952     assert(!hr->is_young(), "not expecting to find young regions");
 953     _hr_printer->post_compaction(hr);
 954     return false;
 955   }
 956 
 957   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
 958     : _hr_printer(hr_printer) { }
 959 };
 960 
 961 void G1CollectedHeap::print_hrm_post_compaction() {
 962   if (_hr_printer.is_active()) {
 963     PostCompactionPrinterClosure cl(hr_printer());
 964     heap_region_iterate(&cl);
 965   }
 966 }
 967 
 968 void G1CollectedHeap::abort_concurrent_cycle() {
 969   // If we start the compaction before the CM threads finish
 970   // scanning the root regions we might trip them over as we'll
 971   // be moving objects / updating references. So let's wait until
 972   // they are done. By telling them to abort, they should complete
 973   // early.
 974   _cm->root_regions()->abort();
 975   _cm->root_regions()->wait_until_scan_finished();
 976 
 977   // Disable discovery and empty the discovered lists
 978   // for the CM ref processor.
 979   _ref_processor_cm->disable_discovery();
 980   _ref_processor_cm->abandon_partial_discovery();
 981   _ref_processor_cm->verify_no_references_recorded();
 982 
 983   // Abandon current iterations of concurrent marking and concurrent
 984   // refinement, if any are in progress.
 985   concurrent_mark()->concurrent_cycle_abort();
 986 }
 987 
 988 void G1CollectedHeap::prepare_heap_for_full_collection() {
 989   // Make sure we'll choose a new allocation region afterwards.
 990   _allocator->release_mutator_alloc_region();
 991   _allocator->abandon_gc_alloc_regions();
 992   g1_rem_set()->cleanupHRRS();
 993 
 994   // We may have added regions to the current incremental collection
 995   // set between the last GC or pause and now. We need to clear the
 996   // incremental collection set and then start rebuilding it afresh
 997   // after this full GC.
 998   abandon_collection_set(collection_set());
 999 
1000   tear_down_region_sets(false /* free_list_only */);
1001 }
1002 
1003 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1004   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1005   assert(used() == recalculate_used(), "Should be equal");
1006   _verifier->verify_region_sets_optional();
1007   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1008   _verifier->check_bitmaps("Full GC Start");
1009 }
1010 
1011 void G1CollectedHeap::prepare_heap_for_mutators() {
1012   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1013   ClassLoaderDataGraph::purge();
1014   MetaspaceUtils::verify_metrics();
1015 
1016   // Prepare heap for normal collections.
1017   assert(num_free_regions() == 0, "we should not have added any free regions");
1018   rebuild_region_sets(false /* free_list_only */);
1019   abort_refinement();
1020   resize_if_necessary_after_full_collection();
1021 
1022   // Rebuild the strong code root lists for each region
1023   rebuild_strong_code_roots();
1024 
1025   // Start a new incremental collection set for the next pause
1026   start_new_collection_set();
1027 
1028   _allocator->init_mutator_alloc_region();
1029 
1030   // Post collection state updates.
1031   MetaspaceGC::compute_new_size();
1032 }
1033 
1034 void G1CollectedHeap::abort_refinement() {
1035   if (_hot_card_cache->use_cache()) {
1036     _hot_card_cache->reset_hot_cache();
1037   }
1038 
1039   // Discard all remembered set updates.
1040   G1BarrierSet::dirty_card_queue_set().abandon_logs();
1041   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1042 }
1043 
1044 void G1CollectedHeap::verify_after_full_collection() {
1045   _hrm.verify_optional();
1046   _verifier->verify_region_sets_optional();
1047   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1048   // Clear the previous marking bitmap, if needed for bitmap verification.
1049   // Note we cannot do this when we clear the next marking bitmap in
1050   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1051   // objects marked during a full GC against the previous bitmap.
1052   // But we need to clear it before calling check_bitmaps below since
1053   // the full GC has compacted objects and updated TAMS but not updated
1054   // the prev bitmap.
1055   if (G1VerifyBitmaps) {
1056     GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1057     _cm->clear_prev_bitmap(workers());
1058   }
1059   _verifier->check_bitmaps("Full GC End");
1060 
1061   // At this point there should be no regions in the
1062   // entire heap tagged as young.
1063   assert(check_young_list_empty(), "young list should be empty at this point");
1064 
1065   // Note: since we've just done a full GC, concurrent
1066   // marking is no longer active. Therefore we need not
1067   // re-enable reference discovery for the CM ref processor.
1068   // That will be done at the start of the next marking cycle.
1069   // We also know that the STW processor should no longer
1070   // discover any new references.
1071   assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1072   assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1073   _ref_processor_stw->verify_no_references_recorded();
1074   _ref_processor_cm->verify_no_references_recorded();
1075 }
1076 
1077 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1078   // Post collection logging.
1079   // We should do this after we potentially resize the heap so
1080   // that all the COMMIT / UNCOMMIT events are generated before
1081   // the compaction events.
1082   print_hrm_post_compaction();
1083   heap_transition->print();
1084   print_heap_after_gc();
1085   print_heap_regions();
1086 #ifdef TRACESPINNING
1087   ParallelTaskTerminator::print_termination_counts();
1088 #endif
1089 }
1090 
1091 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1092                                          bool clear_all_soft_refs) {
1093   assert_at_safepoint_on_vm_thread();
1094 
1095   if (GCLocker::check_active_before_gc()) {
1096     // Full GC was not completed.
1097     return false;
1098   }
1099 
1100   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1101       soft_ref_policy()->should_clear_all_soft_refs();
1102 
1103   G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1104   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1105 
1106   collector.prepare_collection();
1107   collector.collect();
1108   collector.complete_collection();
1109 
1110   // Full collection was successfully completed.
1111   return true;
1112 }
1113 
1114 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1115   // Currently, there is no facility in the do_full_collection(bool) API to notify
1116   // the caller that the collection did not succeed (e.g., because it was locked
1117   // out by the GC locker). So, right now, we'll ignore the return value.
1118   bool dummy = do_full_collection(true,                /* explicit_gc */
1119                                   clear_all_soft_refs);
1120 }
1121 
1122 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1123   // Capacity, free and used after the GC counted as full regions to
1124   // include the waste in the following calculations.
1125   const size_t capacity_after_gc = capacity();
1126   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1127 
1128   // This is enforced in arguments.cpp.
1129   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1130          "otherwise the code below doesn't make sense");
1131 
1132   // We don't have floating point command-line arguments
1133   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1134   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1135   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1136   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1137 
1138   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1139   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1140 
1141   // We have to be careful here as these two calculations can overflow
1142   // 32-bit size_t's.
1143   double used_after_gc_d = (double) used_after_gc;
1144   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1145   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1146 
1147   // Let's make sure that they are both under the max heap size, which
1148   // by default will make them fit into a size_t.
1149   double desired_capacity_upper_bound = (double) max_heap_size;
1150   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1151                                     desired_capacity_upper_bound);
1152   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1153                                     desired_capacity_upper_bound);
1154 
1155   // We can now safely turn them into size_t's.
1156   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1157   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1158 
1159   // This assert only makes sense here, before we adjust them
1160   // with respect to the min and max heap size.
1161   assert(minimum_desired_capacity <= maximum_desired_capacity,
1162          "minimum_desired_capacity = " SIZE_FORMAT ", "
1163          "maximum_desired_capacity = " SIZE_FORMAT,
1164          minimum_desired_capacity, maximum_desired_capacity);
1165 
1166   // Should not be greater than the heap max size. No need to adjust
1167   // it with respect to the heap min size as it's a lower bound (i.e.,
1168   // we'll try to make the capacity larger than it, not smaller).
1169   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1170   // Should not be less than the heap min size. No need to adjust it
1171   // with respect to the heap max size as it's an upper bound (i.e.,
1172   // we'll try to make the capacity smaller than it, not greater).
1173   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1174 
1175   if (capacity_after_gc < minimum_desired_capacity) {
1176     // Don't expand unless it's significant
1177     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1178 
1179     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1180                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1181                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1182                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1183 
1184     expand(expand_bytes, _workers);
1185 
1186     // No expansion, now see if we want to shrink
1187   } else if (capacity_after_gc > maximum_desired_capacity) {
1188     // Capacity too large, compute shrinking size
1189     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1190 
1191     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1192                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1193                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1194                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1195 
1196     shrink(shrink_bytes);
1197   }
1198 }
1199 
1200 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1201                                                             bool do_gc,
1202                                                             bool clear_all_soft_refs,
1203                                                             bool expect_null_mutator_alloc_region,
1204                                                             bool* gc_succeeded) {
1205   *gc_succeeded = true;
1206   // Let's attempt the allocation first.
1207   HeapWord* result =
1208     attempt_allocation_at_safepoint(word_size,
1209                                     expect_null_mutator_alloc_region);
1210   if (result != NULL) {
1211     return result;
1212   }
1213 
1214   // In a G1 heap, we're supposed to keep allocation from failing by
1215   // incremental pauses.  Therefore, at least for now, we'll favor
1216   // expansion over collection.  (This might change in the future if we can
1217   // do something smarter than full collection to satisfy a failed alloc.)
1218   result = expand_and_allocate(word_size);
1219   if (result != NULL) {
1220     return result;
1221   }
1222 
1223   if (do_gc) {
1224     // Expansion didn't work, we'll try to do a Full GC.
1225     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1226                                        clear_all_soft_refs);
1227   }
1228 
1229   return NULL;
1230 }
1231 
1232 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1233                                                      bool* succeeded) {
1234   assert_at_safepoint_on_vm_thread();
1235 
1236   // Attempts to allocate followed by Full GC.
1237   HeapWord* result =
1238     satisfy_failed_allocation_helper(word_size,
1239                                      true,  /* do_gc */
1240                                      false, /* clear_all_soft_refs */
1241                                      false, /* expect_null_mutator_alloc_region */
1242                                      succeeded);
1243 
1244   if (result != NULL || !*succeeded) {
1245     return result;
1246   }
1247 
1248   // Attempts to allocate followed by Full GC that will collect all soft references.
1249   result = satisfy_failed_allocation_helper(word_size,
1250                                             true, /* do_gc */
1251                                             true, /* clear_all_soft_refs */
1252                                             true, /* expect_null_mutator_alloc_region */
1253                                             succeeded);
1254 
1255   if (result != NULL || !*succeeded) {
1256     return result;
1257   }
1258 
1259   // Attempts to allocate, no GC
1260   result = satisfy_failed_allocation_helper(word_size,
1261                                             false, /* do_gc */
1262                                             false, /* clear_all_soft_refs */
1263                                             true,  /* expect_null_mutator_alloc_region */
1264                                             succeeded);
1265 
1266   if (result != NULL) {
1267     return result;
1268   }
1269 
1270   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1271          "Flag should have been handled and cleared prior to this point");
1272 
1273   // What else?  We might try synchronous finalization later.  If the total
1274   // space available is large enough for the allocation, then a more
1275   // complete compaction phase than we've tried so far might be
1276   // appropriate.
1277   return NULL;
1278 }
1279 
1280 // Attempting to expand the heap sufficiently
1281 // to support an allocation of the given "word_size".  If
1282 // successful, perform the allocation and return the address of the
1283 // allocated block, or else "NULL".
1284 
1285 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1286   assert_at_safepoint_on_vm_thread();
1287 
1288   _verifier->verify_region_sets_optional();
1289 
1290   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1291   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1292                             word_size * HeapWordSize);
1293 
1294 
1295   if (expand(expand_bytes, _workers)) {
1296     _hrm.verify_optional();
1297     _verifier->verify_region_sets_optional();
1298     return attempt_allocation_at_safepoint(word_size,
1299                                            false /* expect_null_mutator_alloc_region */);
1300   }
1301   return NULL;
1302 }
1303 
1304 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1305   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1306   aligned_expand_bytes = align_up(aligned_expand_bytes,
1307                                        HeapRegion::GrainBytes);
1308 
1309   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1310                             expand_bytes, aligned_expand_bytes);
1311 
1312   if (is_maximal_no_gc()) {
1313     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1314     return false;
1315   }
1316 
1317   double expand_heap_start_time_sec = os::elapsedTime();
1318   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1319   assert(regions_to_expand > 0, "Must expand by at least one region");
1320 
1321   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1322   if (expand_time_ms != NULL) {
1323     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1324   }
1325 
1326   if (expanded_by > 0) {
1327     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1328     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1329     g1_policy()->record_new_heap_size(num_regions());
1330   } else {
1331     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1332 
1333     // The expansion of the virtual storage space was unsuccessful.
1334     // Let's see if it was because we ran out of swap.
1335     if (G1ExitOnExpansionFailure &&
1336         _hrm.available() >= regions_to_expand) {
1337       // We had head room...
1338       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1339     }
1340   }
1341   return regions_to_expand > 0;
1342 }
1343 
1344 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1345   size_t aligned_shrink_bytes =
1346     ReservedSpace::page_align_size_down(shrink_bytes);
1347   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1348                                          HeapRegion::GrainBytes);
1349   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1350 
1351   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1352   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1353 
1354 
1355   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",
1356                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1357   if (num_regions_removed > 0) {
1358     g1_policy()->record_new_heap_size(num_regions());
1359   } else {
1360     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1361   }
1362 }
1363 
1364 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1365   _verifier->verify_region_sets_optional();
1366 
1367   // We should only reach here at the end of a Full GC which means we
1368   // should not not be holding to any GC alloc regions. The method
1369   // below will make sure of that and do any remaining clean up.
1370   _allocator->abandon_gc_alloc_regions();
1371 
1372   // Instead of tearing down / rebuilding the free lists here, we
1373   // could instead use the remove_all_pending() method on free_list to
1374   // remove only the ones that we need to remove.
1375   tear_down_region_sets(true /* free_list_only */);
1376   shrink_helper(shrink_bytes);
1377   rebuild_region_sets(true /* free_list_only */);
1378 
1379   _hrm.verify_optional();
1380   _verifier->verify_region_sets_optional();
1381 }
1382 
1383 // Public methods.
1384 
1385 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1386   CollectedHeap(),
1387   _young_gen_sampling_thread(NULL),
1388   _collector_policy(collector_policy),
1389   _soft_ref_policy(),
1390   _card_table(NULL),
1391   _memory_manager("G1 Young Generation", "end of minor GC"),
1392   _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1393   _eden_pool(NULL),
1394   _survivor_pool(NULL),
1395   _old_pool(NULL),
1396   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1397   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1398   _g1_policy(new G1Policy(_gc_timer_stw)),
1399   _collection_set(this, _g1_policy),
1400   _dirty_card_queue_set(false),
1401   _ref_processor_stw(NULL),
1402   _is_alive_closure_stw(this),
1403   _is_subject_to_discovery_stw(this),
1404   _ref_processor_cm(NULL),
1405   _is_alive_closure_cm(this),
1406   _is_subject_to_discovery_cm(this),
1407   _bot(NULL),
1408   _hot_card_cache(NULL),
1409   _g1_rem_set(NULL),
1410   _cr(NULL),
1411   _g1mm(NULL),
1412   _preserved_marks_set(true /* in_c_heap */),
1413   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1414   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1415   _humongous_reclaim_candidates(),
1416   _has_humongous_reclaim_candidates(false),
1417   _archive_allocator(NULL),
1418   _summary_bytes_used(0),
1419   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1420   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1421   _expand_heap_after_alloc_failure(true),
1422   _old_marking_cycles_started(0),
1423   _old_marking_cycles_completed(0),
1424   _in_cset_fast_test() {
1425 
1426   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1427                           /* are_GC_task_threads */true,
1428                           /* are_ConcurrentGC_threads */false);
1429   _workers->initialize_workers();
1430   _verifier = new G1HeapVerifier(this);
1431 
1432   _allocator = new G1Allocator(this);
1433 
1434   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1435 
1436   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1437 
1438   // Override the default _filler_array_max_size so that no humongous filler
1439   // objects are created.
1440   _filler_array_max_size = _humongous_object_threshold_in_words;
1441 
1442   uint n_queues = ParallelGCThreads;
1443   _task_queues = new RefToScanQueueSet(n_queues);
1444 
1445   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1446 
1447   for (uint i = 0; i < n_queues; i++) {
1448     RefToScanQueue* q = new RefToScanQueue();
1449     q->initialize();
1450     _task_queues->register_queue(i, q);
1451     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1452   }
1453 
1454   // Initialize the G1EvacuationFailureALot counters and flags.
1455   NOT_PRODUCT(reset_evacuation_should_fail();)
1456 
1457   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1458 }
1459 
1460 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1461                                                                  size_t size,
1462                                                                  size_t translation_factor) {
1463   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1464   // Allocate a new reserved space, preferring to use large pages.
1465   ReservedSpace rs(size, preferred_page_size);
1466   G1RegionToSpaceMapper* result  =
1467     G1RegionToSpaceMapper::create_mapper(rs,
1468                                          size,
1469                                          rs.alignment(),
1470                                          HeapRegion::GrainBytes,
1471                                          translation_factor,
1472                                          mtGC);
1473 
1474   os::trace_page_sizes_for_requested_size(description,
1475                                           size,
1476                                           preferred_page_size,
1477                                           rs.alignment(),
1478                                           rs.base(),
1479                                           rs.size());
1480 
1481   return result;
1482 }
1483 
1484 jint G1CollectedHeap::initialize_concurrent_refinement() {
1485   jint ecode = JNI_OK;
1486   _cr = G1ConcurrentRefine::create(&ecode);
1487   return ecode;
1488 }
1489 
1490 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1491   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1492   if (_young_gen_sampling_thread->osthread() == NULL) {
1493     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1494     return JNI_ENOMEM;
1495   }
1496   return JNI_OK;
1497 }
1498 
1499 jint G1CollectedHeap::initialize() {
1500   os::enable_vtime();
1501 
1502   // Necessary to satisfy locking discipline assertions.
1503 
1504   MutexLocker x(Heap_lock);
1505 
1506   // While there are no constraints in the GC code that HeapWordSize
1507   // be any particular value, there are multiple other areas in the
1508   // system which believe this to be true (e.g. oop->object_size in some
1509   // cases incorrectly returns the size in wordSize units rather than
1510   // HeapWordSize).
1511   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1512 
1513   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1514   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1515   size_t heap_alignment = collector_policy()->heap_alignment();
1516 
1517   // Ensure that the sizes are properly aligned.
1518   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1519   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1520   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1521 
1522   // Reserve the maximum.
1523 
1524   // When compressed oops are enabled, the preferred heap base
1525   // is calculated by subtracting the requested size from the
1526   // 32Gb boundary and using the result as the base address for
1527   // heap reservation. If the requested size is not aligned to
1528   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1529   // into the ReservedHeapSpace constructor) then the actual
1530   // base of the reserved heap may end up differing from the
1531   // address that was requested (i.e. the preferred heap base).
1532   // If this happens then we could end up using a non-optimal
1533   // compressed oops mode.
1534 
1535   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1536                                                  heap_alignment);
1537 
1538   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1539 
1540   // Create the barrier set for the entire reserved region.
1541   G1CardTable* ct = new G1CardTable(reserved_region());
1542   ct->initialize();
1543   G1BarrierSet* bs = new G1BarrierSet(ct);
1544   bs->initialize();
1545   assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1546   BarrierSet::set_barrier_set(bs);
1547   _card_table = ct;
1548 
1549   // Create the hot card cache.
1550   _hot_card_cache = new G1HotCardCache(this);
1551 
1552   // Carve out the G1 part of the heap.
1553   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1554   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1555   G1RegionToSpaceMapper* heap_storage =
1556     G1RegionToSpaceMapper::create_mapper(g1_rs,
1557                                          g1_rs.size(),
1558                                          page_size,
1559                                          HeapRegion::GrainBytes,
1560                                          1,
1561                                          mtJavaHeap);
1562   os::trace_page_sizes("Heap",
1563                        collector_policy()->min_heap_byte_size(),
1564                        max_byte_size,
1565                        page_size,
1566                        heap_rs.base(),
1567                        heap_rs.size());
1568   heap_storage->set_mapping_changed_listener(&_listener);
1569 
1570   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1571   G1RegionToSpaceMapper* bot_storage =
1572     create_aux_memory_mapper("Block Offset Table",
1573                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1574                              G1BlockOffsetTable::heap_map_factor());
1575 
1576   G1RegionToSpaceMapper* cardtable_storage =
1577     create_aux_memory_mapper("Card Table",
1578                              G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1579                              G1CardTable::heap_map_factor());
1580 
1581   G1RegionToSpaceMapper* card_counts_storage =
1582     create_aux_memory_mapper("Card Counts Table",
1583                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1584                              G1CardCounts::heap_map_factor());
1585 
1586   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1587   G1RegionToSpaceMapper* prev_bitmap_storage =
1588     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1589   G1RegionToSpaceMapper* next_bitmap_storage =
1590     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1591 
1592   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1593   _card_table->initialize(cardtable_storage);
1594   // Do later initialization work for concurrent refinement.
1595   _hot_card_cache->initialize(card_counts_storage);
1596 
1597   // 6843694 - ensure that the maximum region index can fit
1598   // in the remembered set structures.
1599   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1600   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1601 
1602   // Also create a G1 rem set.
1603   _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1604   _g1_rem_set->initialize(max_capacity(), max_regions());
1605 
1606   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1607   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1608   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1609             "too many cards per region");
1610 
1611   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1612 
1613   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1614 
1615   {
1616     HeapWord* start = _hrm.reserved().start();
1617     HeapWord* end = _hrm.reserved().end();
1618     size_t granularity = HeapRegion::GrainBytes;
1619 
1620     _in_cset_fast_test.initialize(start, end, granularity);
1621     _humongous_reclaim_candidates.initialize(start, end, granularity);
1622   }
1623 
1624   // Create the G1ConcurrentMark data structure and thread.
1625   // (Must do this late, so that "max_regions" is defined.)
1626   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1627   if (_cm == NULL || !_cm->completed_initialization()) {
1628     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1629     return JNI_ENOMEM;
1630   }
1631   _cm_thread = _cm->cm_thread();
1632 
1633   // Now expand into the initial heap size.
1634   if (!expand(init_byte_size, _workers)) {
1635     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1636     return JNI_ENOMEM;
1637   }
1638 
1639   // Perform any initialization actions delegated to the policy.
1640   g1_policy()->init(this, &_collection_set);
1641 
1642   G1BarrierSet::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1643                                                  SATB_Q_FL_lock,
1644                                                  G1SATBProcessCompletedThreshold,
1645                                                  Shared_SATB_Q_lock);
1646 
1647   jint ecode = initialize_concurrent_refinement();
1648   if (ecode != JNI_OK) {
1649     return ecode;
1650   }
1651 
1652   ecode = initialize_young_gen_sampling_thread();
1653   if (ecode != JNI_OK) {
1654     return ecode;
1655   }
1656 
1657   G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1658                                                   DirtyCardQ_FL_lock,
1659                                                   (int)concurrent_refine()->yellow_zone(),
1660                                                   (int)concurrent_refine()->red_zone(),
1661                                                   Shared_DirtyCardQ_lock,
1662                                                   NULL,  // fl_owner
1663                                                   true); // init_free_ids
1664 
1665   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1666                                     DirtyCardQ_FL_lock,
1667                                     -1, // never trigger processing
1668                                     -1, // no limit on length
1669                                     Shared_DirtyCardQ_lock,
1670                                     &G1BarrierSet::dirty_card_queue_set());
1671 
1672   // Here we allocate the dummy HeapRegion that is required by the
1673   // G1AllocRegion class.
1674   HeapRegion* dummy_region = _hrm.get_dummy_region();
1675 
1676   // We'll re-use the same region whether the alloc region will
1677   // require BOT updates or not and, if it doesn't, then a non-young
1678   // region will complain that it cannot support allocations without
1679   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1680   dummy_region->set_eden();
1681   // Make sure it's full.
1682   dummy_region->set_top(dummy_region->end());
1683   G1AllocRegion::setup(this, dummy_region);
1684 
1685   _allocator->init_mutator_alloc_region();
1686 
1687   // Do create of the monitoring and management support so that
1688   // values in the heap have been properly initialized.
1689   _g1mm = new G1MonitoringSupport(this);
1690 
1691   G1StringDedup::initialize();
1692 
1693   _preserved_marks_set.init(ParallelGCThreads);
1694 
1695   _collection_set.initialize(max_regions());
1696 
1697   return JNI_OK;
1698 }
1699 
1700 void G1CollectedHeap::initialize_serviceability() {
1701   _eden_pool = new G1EdenPool(this);
1702   _survivor_pool = new G1SurvivorPool(this);
1703   _old_pool = new G1OldGenPool(this);
1704 
1705   _full_gc_memory_manager.add_pool(_eden_pool);
1706   _full_gc_memory_manager.add_pool(_survivor_pool);
1707   _full_gc_memory_manager.add_pool(_old_pool);
1708 
1709   _memory_manager.add_pool(_eden_pool);
1710   _memory_manager.add_pool(_survivor_pool);
1711 
1712 }
1713 
1714 void G1CollectedHeap::stop() {
1715   // Stop all concurrent threads. We do this to make sure these threads
1716   // do not continue to execute and access resources (e.g. logging)
1717   // that are destroyed during shutdown.
1718   _cr->stop();
1719   _young_gen_sampling_thread->stop();
1720   _cm_thread->stop();
1721   if (G1StringDedup::is_enabled()) {
1722     G1StringDedup::stop();
1723   }
1724 }
1725 
1726 void G1CollectedHeap::safepoint_synchronize_begin() {
1727   SuspendibleThreadSet::synchronize();
1728 }
1729 
1730 void G1CollectedHeap::safepoint_synchronize_end() {
1731   SuspendibleThreadSet::desynchronize();
1732 }
1733 
1734 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1735   return HeapRegion::max_region_size();
1736 }
1737 
1738 void G1CollectedHeap::post_initialize() {
1739   CollectedHeap::post_initialize();
1740   ref_processing_init();
1741 }
1742 
1743 void G1CollectedHeap::ref_processing_init() {
1744   // Reference processing in G1 currently works as follows:
1745   //
1746   // * There are two reference processor instances. One is
1747   //   used to record and process discovered references
1748   //   during concurrent marking; the other is used to
1749   //   record and process references during STW pauses
1750   //   (both full and incremental).
1751   // * Both ref processors need to 'span' the entire heap as
1752   //   the regions in the collection set may be dotted around.
1753   //
1754   // * For the concurrent marking ref processor:
1755   //   * Reference discovery is enabled at initial marking.
1756   //   * Reference discovery is disabled and the discovered
1757   //     references processed etc during remarking.
1758   //   * Reference discovery is MT (see below).
1759   //   * Reference discovery requires a barrier (see below).
1760   //   * Reference processing may or may not be MT
1761   //     (depending on the value of ParallelRefProcEnabled
1762   //     and ParallelGCThreads).
1763   //   * A full GC disables reference discovery by the CM
1764   //     ref processor and abandons any entries on it's
1765   //     discovered lists.
1766   //
1767   // * For the STW processor:
1768   //   * Non MT discovery is enabled at the start of a full GC.
1769   //   * Processing and enqueueing during a full GC is non-MT.
1770   //   * During a full GC, references are processed after marking.
1771   //
1772   //   * Discovery (may or may not be MT) is enabled at the start
1773   //     of an incremental evacuation pause.
1774   //   * References are processed near the end of a STW evacuation pause.
1775   //   * For both types of GC:
1776   //     * Discovery is atomic - i.e. not concurrent.
1777   //     * Reference discovery will not need a barrier.
1778 
1779   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1780 
1781   // Concurrent Mark ref processor
1782   _ref_processor_cm =
1783     new ReferenceProcessor(&_is_subject_to_discovery_cm,
1784                            mt_processing,                                  // mt processing
1785                            ParallelGCThreads,                              // degree of mt processing
1786                            (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1787                            MAX2(ParallelGCThreads, ConcGCThreads),         // degree of mt discovery
1788                            false,                                          // Reference discovery is not atomic
1789                            &_is_alive_closure_cm);                         // is alive closure
1790 
1791   // STW ref processor
1792   _ref_processor_stw =
1793     new ReferenceProcessor(&_is_subject_to_discovery_stw,                 
1794                            mt_processing,                        // mt processing
1795                            ParallelGCThreads,                    // degree of mt processing
1796                            (ParallelGCThreads > 1),              // mt discovery
1797                            ParallelGCThreads,                    // degree of mt discovery
1798                            true,                                 // Reference discovery is atomic
1799                            &_is_alive_closure_stw);              // is alive closure
1800 }
1801 
1802 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1803   return _collector_policy;
1804 }
1805 
1806 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1807   return &_soft_ref_policy;
1808 }
1809 
1810 size_t G1CollectedHeap::capacity() const {
1811   return _hrm.length() * HeapRegion::GrainBytes;
1812 }
1813 
1814 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1815   return _hrm.total_free_bytes();
1816 }
1817 
1818 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1819   _hot_card_cache->drain(cl, worker_i);
1820 }
1821 
1822 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1823   DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1824   size_t n_completed_buffers = 0;
1825   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1826     n_completed_buffers++;
1827   }
1828   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1829   dcqs.clear_n_completed_buffers();
1830   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1831 }
1832 
1833 // Computes the sum of the storage used by the various regions.
1834 size_t G1CollectedHeap::used() const {
1835   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1836   if (_archive_allocator != NULL) {
1837     result += _archive_allocator->used();
1838   }
1839   return result;
1840 }
1841 
1842 size_t G1CollectedHeap::used_unlocked() const {
1843   return _summary_bytes_used;
1844 }
1845 
1846 class SumUsedClosure: public HeapRegionClosure {
1847   size_t _used;
1848 public:
1849   SumUsedClosure() : _used(0) {}
1850   bool do_heap_region(HeapRegion* r) {
1851     _used += r->used();
1852     return false;
1853   }
1854   size_t result() { return _used; }
1855 };
1856 
1857 size_t G1CollectedHeap::recalculate_used() const {
1858   double recalculate_used_start = os::elapsedTime();
1859 
1860   SumUsedClosure blk;
1861   heap_region_iterate(&blk);
1862 
1863   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1864   return blk.result();
1865 }
1866 
1867 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1868   switch (cause) {
1869     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1870     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1871     case GCCause::_wb_conc_mark:                        return true;
1872     default :                                           return false;
1873   }
1874 }
1875 
1876 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1877   switch (cause) {
1878     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
1879     case GCCause::_g1_humongous_allocation: return true;
1880     default:                                return is_user_requested_concurrent_full_gc(cause);
1881   }
1882 }
1883 
1884 #ifndef PRODUCT
1885 void G1CollectedHeap::allocate_dummy_regions() {
1886   // Let's fill up most of the region
1887   size_t word_size = HeapRegion::GrainWords - 1024;
1888   // And as a result the region we'll allocate will be humongous.
1889   guarantee(is_humongous(word_size), "sanity");
1890 
1891   // _filler_array_max_size is set to humongous object threshold
1892   // but temporarily change it to use CollectedHeap::fill_with_object().
1893   SizeTFlagSetting fs(_filler_array_max_size, word_size);
1894 
1895   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1896     // Let's use the existing mechanism for the allocation
1897     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1898     if (dummy_obj != NULL) {
1899       MemRegion mr(dummy_obj, word_size);
1900       CollectedHeap::fill_with_object(mr);
1901     } else {
1902       // If we can't allocate once, we probably cannot allocate
1903       // again. Let's get out of the loop.
1904       break;
1905     }
1906   }
1907 }
1908 #endif // !PRODUCT
1909 
1910 void G1CollectedHeap::increment_old_marking_cycles_started() {
1911   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1912          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1913          "Wrong marking cycle count (started: %d, completed: %d)",
1914          _old_marking_cycles_started, _old_marking_cycles_completed);
1915 
1916   _old_marking_cycles_started++;
1917 }
1918 
1919 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
1920   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
1921 
1922   // We assume that if concurrent == true, then the caller is a
1923   // concurrent thread that was joined the Suspendible Thread
1924   // Set. If there's ever a cheap way to check this, we should add an
1925   // assert here.
1926 
1927   // Given that this method is called at the end of a Full GC or of a
1928   // concurrent cycle, and those can be nested (i.e., a Full GC can
1929   // interrupt a concurrent cycle), the number of full collections
1930   // completed should be either one (in the case where there was no
1931   // nesting) or two (when a Full GC interrupted a concurrent cycle)
1932   // behind the number of full collections started.
1933 
1934   // This is the case for the inner caller, i.e. a Full GC.
1935   assert(concurrent ||
1936          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1937          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1938          "for inner caller (Full GC): _old_marking_cycles_started = %u "
1939          "is inconsistent with _old_marking_cycles_completed = %u",
1940          _old_marking_cycles_started, _old_marking_cycles_completed);
1941 
1942   // This is the case for the outer caller, i.e. the concurrent cycle.
1943   assert(!concurrent ||
1944          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1945          "for outer caller (concurrent cycle): "
1946          "_old_marking_cycles_started = %u "
1947          "is inconsistent with _old_marking_cycles_completed = %u",
1948          _old_marking_cycles_started, _old_marking_cycles_completed);
1949 
1950   _old_marking_cycles_completed += 1;
1951 
1952   // We need to clear the "in_progress" flag in the CM thread before
1953   // we wake up any waiters (especially when ExplicitInvokesConcurrent
1954   // is set) so that if a waiter requests another System.gc() it doesn't
1955   // incorrectly see that a marking cycle is still in progress.
1956   if (concurrent) {
1957     _cm_thread->set_idle();
1958   }
1959 
1960   // This notify_all() will ensure that a thread that called
1961   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
1962   // and it's waiting for a full GC to finish will be woken up. It is
1963   // waiting in VM_G1CollectForAllocation::doit_epilogue().
1964   FullGCCount_lock->notify_all();
1965 }
1966 
1967 void G1CollectedHeap::collect(GCCause::Cause cause) {
1968   assert_heap_not_locked();
1969 
1970   uint gc_count_before;
1971   uint old_marking_count_before;
1972   uint full_gc_count_before;
1973   bool retry_gc;
1974 
1975   do {
1976     retry_gc = false;
1977 
1978     {
1979       MutexLocker ml(Heap_lock);
1980 
1981       // Read the GC count while holding the Heap_lock
1982       gc_count_before = total_collections();
1983       full_gc_count_before = total_full_collections();
1984       old_marking_count_before = _old_marking_cycles_started;
1985     }
1986 
1987     if (should_do_concurrent_full_gc(cause)) {
1988       // Schedule an initial-mark evacuation pause that will start a
1989       // concurrent cycle. We're setting word_size to 0 which means that
1990       // we are not requesting a post-GC allocation.
1991       VM_G1CollectForAllocation op(0,     /* word_size */
1992                                    gc_count_before,
1993                                    cause,
1994                                    true,  /* should_initiate_conc_mark */
1995                                    g1_policy()->max_pause_time_ms());
1996       VMThread::execute(&op);
1997       if (!op.pause_succeeded()) {
1998         if (old_marking_count_before == _old_marking_cycles_started) {
1999           retry_gc = op.should_retry_gc();
2000         } else {
2001           // A Full GC happened while we were trying to schedule the
2002           // initial-mark GC. No point in starting a new cycle given
2003           // that the whole heap was collected anyway.
2004         }
2005 
2006         if (retry_gc) {
2007           if (GCLocker::is_active_and_needs_gc()) {
2008             GCLocker::stall_until_clear();
2009           }
2010         }
2011       }
2012     } else {
2013       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2014           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2015 
2016         // Schedule a standard evacuation pause. We're setting word_size
2017         // to 0 which means that we are not requesting a post-GC allocation.
2018         VM_G1CollectForAllocation op(0,     /* word_size */
2019                                      gc_count_before,
2020                                      cause,
2021                                      false, /* should_initiate_conc_mark */
2022                                      g1_policy()->max_pause_time_ms());
2023         VMThread::execute(&op);
2024       } else {
2025         // Schedule a Full GC.
2026         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2027         VMThread::execute(&op);
2028       }
2029     }
2030   } while (retry_gc);
2031 }
2032 
2033 bool G1CollectedHeap::is_in(const void* p) const {
2034   if (_hrm.reserved().contains(p)) {
2035     // Given that we know that p is in the reserved space,
2036     // heap_region_containing() should successfully
2037     // return the containing region.
2038     HeapRegion* hr = heap_region_containing(p);
2039     return hr->is_in(p);
2040   } else {
2041     return false;
2042   }
2043 }
2044 
2045 #ifdef ASSERT
2046 bool G1CollectedHeap::is_in_exact(const void* p) const {
2047   bool contains = reserved_region().contains(p);
2048   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2049   if (contains && available) {
2050     return true;
2051   } else {
2052     return false;
2053   }
2054 }
2055 #endif
2056 
2057 // Iteration functions.
2058 
2059 // Iterates an ObjectClosure over all objects within a HeapRegion.
2060 
2061 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2062   ObjectClosure* _cl;
2063 public:
2064   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2065   bool do_heap_region(HeapRegion* r) {
2066     if (!r->is_continues_humongous()) {
2067       r->object_iterate(_cl);
2068     }
2069     return false;
2070   }
2071 };
2072 
2073 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2074   IterateObjectClosureRegionClosure blk(cl);
2075   heap_region_iterate(&blk);
2076 }
2077 
2078 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2079   _hrm.iterate(cl);
2080 }
2081 
2082 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2083                                                                  HeapRegionClaimer *hrclaimer,
2084                                                                  uint worker_id) const {
2085   _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2086 }
2087 
2088 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2089                                                          HeapRegionClaimer *hrclaimer) const {
2090   _hrm.par_iterate(cl, hrclaimer, 0);
2091 }
2092 
2093 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2094   _collection_set.iterate(cl);
2095 }
2096 
2097 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2098   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2099 }
2100 
2101 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2102   HeapRegion* hr = heap_region_containing(addr);
2103   return hr->block_start(addr);
2104 }
2105 
2106 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2107   HeapRegion* hr = heap_region_containing(addr);
2108   return hr->block_size(addr);
2109 }
2110 
2111 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2112   HeapRegion* hr = heap_region_containing(addr);
2113   return hr->block_is_obj(addr);
2114 }
2115 
2116 bool G1CollectedHeap::supports_tlab_allocation() const {
2117   return true;
2118 }
2119 
2120 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2121   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2122 }
2123 
2124 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2125   return _eden.length() * HeapRegion::GrainBytes;
2126 }
2127 
2128 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2129 // must be equal to the humongous object limit.
2130 size_t G1CollectedHeap::max_tlab_size() const {
2131   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2132 }
2133 
2134 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2135   return _allocator->unsafe_max_tlab_alloc();
2136 }
2137 
2138 size_t G1CollectedHeap::max_capacity() const {
2139   return _hrm.reserved().byte_size();
2140 }
2141 
2142 jlong G1CollectedHeap::millis_since_last_gc() {
2143   // See the notes in GenCollectedHeap::millis_since_last_gc()
2144   // for more information about the implementation.
2145   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2146     _g1_policy->collection_pause_end_millis();
2147   if (ret_val < 0) {
2148     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2149       ". returning zero instead.", ret_val);
2150     return 0;
2151   }
2152   return ret_val;
2153 }
2154 
2155 void G1CollectedHeap::prepare_for_verify() {
2156   _verifier->prepare_for_verify();
2157 }
2158 
2159 void G1CollectedHeap::verify(VerifyOption vo) {
2160   _verifier->verify(vo);
2161 }
2162 
2163 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2164   return true;
2165 }
2166 
2167 const char* const* G1CollectedHeap::concurrent_phases() const {
2168   return _cm_thread->concurrent_phases();
2169 }
2170 
2171 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2172   return _cm_thread->request_concurrent_phase(phase);
2173 }
2174 
2175 class PrintRegionClosure: public HeapRegionClosure {
2176   outputStream* _st;
2177 public:
2178   PrintRegionClosure(outputStream* st) : _st(st) {}
2179   bool do_heap_region(HeapRegion* r) {
2180     r->print_on(_st);
2181     return false;
2182   }
2183 };
2184 
2185 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2186                                        const HeapRegion* hr,
2187                                        const VerifyOption vo) const {
2188   switch (vo) {
2189   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2190   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2191   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2192   default:                            ShouldNotReachHere();
2193   }
2194   return false; // keep some compilers happy
2195 }
2196 
2197 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2198                                        const VerifyOption vo) const {
2199   switch (vo) {
2200   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2201   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2202   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2203   default:                            ShouldNotReachHere();
2204   }
2205   return false; // keep some compilers happy
2206 }
2207 
2208 void G1CollectedHeap::print_heap_regions() const {
2209   LogTarget(Trace, gc, heap, region) lt;
2210   if (lt.is_enabled()) {
2211     LogStream ls(lt);
2212     print_regions_on(&ls);
2213   }
2214 }
2215 
2216 void G1CollectedHeap::print_on(outputStream* st) const {
2217   st->print(" %-20s", "garbage-first heap");
2218   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2219             capacity()/K, used_unlocked()/K);
2220   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2221             p2i(_hrm.reserved().start()),
2222             p2i(_hrm.reserved().end()));
2223   st->cr();
2224   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2225   uint young_regions = young_regions_count();
2226   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2227             (size_t) young_regions * HeapRegion::GrainBytes / K);
2228   uint survivor_regions = survivor_regions_count();
2229   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2230             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2231   st->cr();
2232   MetaspaceUtils::print_on(st);
2233 }
2234 
2235 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2236   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2237                "HS=humongous(starts), HC=humongous(continues), "
2238                "CS=collection set, F=free, A=archive, "
2239                "TAMS=top-at-mark-start (previous, next)");
2240   PrintRegionClosure blk(st);
2241   heap_region_iterate(&blk);
2242 }
2243 
2244 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2245   print_on(st);
2246 
2247   // Print the per-region information.
2248   print_regions_on(st);
2249 }
2250 
2251 void G1CollectedHeap::print_on_error(outputStream* st) const {
2252   this->CollectedHeap::print_on_error(st);
2253 
2254   if (_cm != NULL) {
2255     st->cr();
2256     _cm->print_on_error(st);
2257   }
2258 }
2259 
2260 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2261   workers()->print_worker_threads_on(st);
2262   _cm_thread->print_on(st);
2263   st->cr();
2264   _cm->print_worker_threads_on(st);
2265   _cr->print_threads_on(st);
2266   _young_gen_sampling_thread->print_on(st);
2267   if (G1StringDedup::is_enabled()) {
2268     G1StringDedup::print_worker_threads_on(st);
2269   }
2270 }
2271 
2272 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2273   workers()->threads_do(tc);
2274   tc->do_thread(_cm_thread);
2275   _cm->threads_do(tc);
2276   _cr->threads_do(tc);
2277   tc->do_thread(_young_gen_sampling_thread);
2278   if (G1StringDedup::is_enabled()) {
2279     G1StringDedup::threads_do(tc);
2280   }
2281 }
2282 
2283 void G1CollectedHeap::print_tracing_info() const {
2284   g1_rem_set()->print_summary_info();
2285   concurrent_mark()->print_summary_info();
2286 }
2287 
2288 #ifndef PRODUCT
2289 // Helpful for debugging RSet issues.
2290 
2291 class PrintRSetsClosure : public HeapRegionClosure {
2292 private:
2293   const char* _msg;
2294   size_t _occupied_sum;
2295 
2296 public:
2297   bool do_heap_region(HeapRegion* r) {
2298     HeapRegionRemSet* hrrs = r->rem_set();
2299     size_t occupied = hrrs->occupied();
2300     _occupied_sum += occupied;
2301 
2302     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2303     if (occupied == 0) {
2304       tty->print_cr("  RSet is empty");
2305     } else {
2306       hrrs->print();
2307     }
2308     tty->print_cr("----------");
2309     return false;
2310   }
2311 
2312   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2313     tty->cr();
2314     tty->print_cr("========================================");
2315     tty->print_cr("%s", msg);
2316     tty->cr();
2317   }
2318 
2319   ~PrintRSetsClosure() {
2320     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2321     tty->print_cr("========================================");
2322     tty->cr();
2323   }
2324 };
2325 
2326 void G1CollectedHeap::print_cset_rsets() {
2327   PrintRSetsClosure cl("Printing CSet RSets");
2328   collection_set_iterate(&cl);
2329 }
2330 
2331 void G1CollectedHeap::print_all_rsets() {
2332   PrintRSetsClosure cl("Printing All RSets");;
2333   heap_region_iterate(&cl);
2334 }
2335 #endif // PRODUCT
2336 
2337 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2338 
2339   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2340   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2341   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2342 
2343   size_t eden_capacity_bytes =
2344     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2345 
2346   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2347   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2348                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2349 }
2350 
2351 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2352   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2353                        stats->unused(), stats->used(), stats->region_end_waste(),
2354                        stats->regions_filled(), stats->direct_allocated(),
2355                        stats->failure_used(), stats->failure_waste());
2356 }
2357 
2358 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2359   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2360   gc_tracer->report_gc_heap_summary(when, heap_summary);
2361 
2362   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2363   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2364 }
2365 
2366 G1CollectedHeap* G1CollectedHeap::heap() {
2367   CollectedHeap* heap = Universe::heap();
2368   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2369   assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2370   return (G1CollectedHeap*)heap;
2371 }
2372 
2373 void G1CollectedHeap::gc_prologue(bool full) {
2374   // always_do_update_barrier = false;
2375   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2376 
2377   // This summary needs to be printed before incrementing total collections.
2378   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2379 
2380   // Update common counters.
2381   increment_total_collections(full /* full gc */);
2382   if (full) {
2383     increment_old_marking_cycles_started();
2384   }
2385 
2386   // Fill TLAB's and such
2387   double start = os::elapsedTime();
2388   accumulate_statistics_all_tlabs();
2389   ensure_parsability(true);
2390   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2391 }
2392 
2393 void G1CollectedHeap::gc_epilogue(bool full) {
2394   // Update common counters.
2395   if (full) {
2396     // Update the number of full collections that have been completed.
2397     increment_old_marking_cycles_completed(false /* concurrent */);
2398   }
2399 
2400   // We are at the end of the GC. Total collections has already been increased.
2401   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2402 
2403   // FIXME: what is this about?
2404   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2405   // is set.
2406 #if COMPILER2_OR_JVMCI
2407   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2408 #endif
2409   // always_do_update_barrier = true;
2410 
2411   double start = os::elapsedTime();
2412   resize_all_tlabs();
2413   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2414 
2415   MemoryService::track_memory_usage();
2416   // We have just completed a GC. Update the soft reference
2417   // policy with the new heap occupancy
2418   Universe::update_heap_info_at_gc();
2419 }
2420 
2421 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2422                                                uint gc_count_before,
2423                                                bool* succeeded,
2424                                                GCCause::Cause gc_cause) {
2425   assert_heap_not_locked_and_not_at_safepoint();
2426   VM_G1CollectForAllocation op(word_size,
2427                                gc_count_before,
2428                                gc_cause,
2429                                false, /* should_initiate_conc_mark */
2430                                g1_policy()->max_pause_time_ms());
2431   VMThread::execute(&op);
2432 
2433   HeapWord* result = op.result();
2434   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2435   assert(result == NULL || ret_succeeded,
2436          "the result should be NULL if the VM did not succeed");
2437   *succeeded = ret_succeeded;
2438 
2439   assert_heap_not_locked();
2440   return result;
2441 }
2442 
2443 void G1CollectedHeap::do_concurrent_mark() {
2444   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2445   if (!_cm_thread->in_progress()) {
2446     _cm_thread->set_started();
2447     CGC_lock->notify();
2448   }
2449 }
2450 
2451 size_t G1CollectedHeap::pending_card_num() {
2452   size_t extra_cards = 0;
2453   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2454     DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2455     extra_cards += dcq.size();
2456   }
2457   DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2458   size_t buffer_size = dcqs.buffer_size();
2459   size_t buffer_num = dcqs.completed_buffers_num();
2460 
2461   return buffer_size * buffer_num + extra_cards;
2462 }
2463 
2464 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2465   // We don't nominate objects with many remembered set entries, on
2466   // the assumption that such objects are likely still live.
2467   HeapRegionRemSet* rem_set = r->rem_set();
2468 
2469   return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2470          rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2471          G1EagerReclaimHumongousObjects && rem_set->is_empty();
2472 }
2473 
2474 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2475  private:
2476   size_t _total_humongous;
2477   size_t _candidate_humongous;
2478 
2479   DirtyCardQueue _dcq;
2480 
2481   bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2482     assert(region->is_starts_humongous(), "Must start a humongous object");
2483 
2484     oop obj = oop(region->bottom());
2485 
2486     // Dead objects cannot be eager reclaim candidates. Due to class
2487     // unloading it is unsafe to query their classes so we return early.
2488     if (g1h->is_obj_dead(obj, region)) {
2489       return false;
2490     }
2491 
2492     // If we do not have a complete remembered set for the region, then we can
2493     // not be sure that we have all references to it.
2494     if (!region->rem_set()->is_complete()) {
2495       return false;
2496     }
2497     // Candidate selection must satisfy the following constraints
2498     // while concurrent marking is in progress:
2499     //
2500     // * In order to maintain SATB invariants, an object must not be
2501     // reclaimed if it was allocated before the start of marking and
2502     // has not had its references scanned.  Such an object must have
2503     // its references (including type metadata) scanned to ensure no
2504     // live objects are missed by the marking process.  Objects
2505     // allocated after the start of concurrent marking don't need to
2506     // be scanned.
2507     //
2508     // * An object must not be reclaimed if it is on the concurrent
2509     // mark stack.  Objects allocated after the start of concurrent
2510     // marking are never pushed on the mark stack.
2511     //
2512     // Nominating only objects allocated after the start of concurrent
2513     // marking is sufficient to meet both constraints.  This may miss
2514     // some objects that satisfy the constraints, but the marking data
2515     // structures don't support efficiently performing the needed
2516     // additional tests or scrubbing of the mark stack.
2517     //
2518     // However, we presently only nominate is_typeArray() objects.
2519     // A humongous object containing references induces remembered
2520     // set entries on other regions.  In order to reclaim such an
2521     // object, those remembered sets would need to be cleaned up.
2522     //
2523     // We also treat is_typeArray() objects specially, allowing them
2524     // to be reclaimed even if allocated before the start of
2525     // concurrent mark.  For this we rely on mark stack insertion to
2526     // exclude is_typeArray() objects, preventing reclaiming an object
2527     // that is in the mark stack.  We also rely on the metadata for
2528     // such objects to be built-in and so ensured to be kept live.
2529     // Frequent allocation and drop of large binary blobs is an
2530     // important use case for eager reclaim, and this special handling
2531     // may reduce needed headroom.
2532 
2533     return obj->is_typeArray() &&
2534            g1h->is_potential_eager_reclaim_candidate(region);
2535   }
2536 
2537  public:
2538   RegisterHumongousWithInCSetFastTestClosure()
2539   : _total_humongous(0),
2540     _candidate_humongous(0),
2541     _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2542   }
2543 
2544   virtual bool do_heap_region(HeapRegion* r) {
2545     if (!r->is_starts_humongous()) {
2546       return false;
2547     }
2548     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2549 
2550     bool is_candidate = humongous_region_is_candidate(g1h, r);
2551     uint rindex = r->hrm_index();
2552     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2553     if (is_candidate) {
2554       _candidate_humongous++;
2555       g1h->register_humongous_region_with_cset(rindex);
2556       // Is_candidate already filters out humongous object with large remembered sets.
2557       // If we have a humongous object with a few remembered sets, we simply flush these
2558       // remembered set entries into the DCQS. That will result in automatic
2559       // re-evaluation of their remembered set entries during the following evacuation
2560       // phase.
2561       if (!r->rem_set()->is_empty()) {
2562         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2563                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2564         G1CardTable* ct = g1h->card_table();
2565         HeapRegionRemSetIterator hrrs(r->rem_set());
2566         size_t card_index;
2567         while (hrrs.has_next(card_index)) {
2568           jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2569           // The remembered set might contain references to already freed
2570           // regions. Filter out such entries to avoid failing card table
2571           // verification.
2572           if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2573             if (*card_ptr != G1CardTable::dirty_card_val()) {
2574               *card_ptr = G1CardTable::dirty_card_val();
2575               _dcq.enqueue(card_ptr);
2576             }
2577           }
2578         }
2579         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2580                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2581                hrrs.n_yielded(), r->rem_set()->occupied());
2582         // We should only clear the card based remembered set here as we will not
2583         // implicitly rebuild anything else during eager reclaim. Note that at the moment
2584         // (and probably never) we do not enter this path if there are other kind of
2585         // remembered sets for this region.
2586         r->rem_set()->clear_locked(true /* only_cardset */);
2587         // Clear_locked() above sets the state to Empty. However we want to continue
2588         // collecting remembered set entries for humongous regions that were not
2589         // reclaimed.
2590         r->rem_set()->set_state_complete();
2591       }
2592       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2593     }
2594     _total_humongous++;
2595 
2596     return false;
2597   }
2598 
2599   size_t total_humongous() const { return _total_humongous; }
2600   size_t candidate_humongous() const { return _candidate_humongous; }
2601 
2602   void flush_rem_set_entries() { _dcq.flush(); }
2603 };
2604 
2605 void G1CollectedHeap::register_humongous_regions_with_cset() {
2606   if (!G1EagerReclaimHumongousObjects) {
2607     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2608     return;
2609   }
2610   double time = os::elapsed_counter();
2611 
2612   // Collect reclaim candidate information and register candidates with cset.
2613   RegisterHumongousWithInCSetFastTestClosure cl;
2614   heap_region_iterate(&cl);
2615 
2616   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2617   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2618                                                                   cl.total_humongous(),
2619                                                                   cl.candidate_humongous());
2620   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2621 
2622   // Finally flush all remembered set entries to re-check into the global DCQS.
2623   cl.flush_rem_set_entries();
2624 }
2625 
2626 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2627   public:
2628     bool do_heap_region(HeapRegion* hr) {
2629       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2630         hr->verify_rem_set();
2631       }
2632       return false;
2633     }
2634 };
2635 
2636 uint G1CollectedHeap::num_task_queues() const {
2637   return _task_queues->size();
2638 }
2639 
2640 #if TASKQUEUE_STATS
2641 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2642   st->print_raw_cr("GC Task Stats");
2643   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2644   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2645 }
2646 
2647 void G1CollectedHeap::print_taskqueue_stats() const {
2648   if (!log_is_enabled(Trace, gc, task, stats)) {
2649     return;
2650   }
2651   Log(gc, task, stats) log;
2652   ResourceMark rm;
2653   LogStream ls(log.trace());
2654   outputStream* st = &ls;
2655 
2656   print_taskqueue_stats_hdr(st);
2657 
2658   TaskQueueStats totals;
2659   const uint n = num_task_queues();
2660   for (uint i = 0; i < n; ++i) {
2661     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2662     totals += task_queue(i)->stats;
2663   }
2664   st->print_raw("tot "); totals.print(st); st->cr();
2665 
2666   DEBUG_ONLY(totals.verify());
2667 }
2668 
2669 void G1CollectedHeap::reset_taskqueue_stats() {
2670   const uint n = num_task_queues();
2671   for (uint i = 0; i < n; ++i) {
2672     task_queue(i)->stats.reset();
2673   }
2674 }
2675 #endif // TASKQUEUE_STATS
2676 
2677 void G1CollectedHeap::wait_for_root_region_scanning() {
2678   double scan_wait_start = os::elapsedTime();
2679   // We have to wait until the CM threads finish scanning the
2680   // root regions as it's the only way to ensure that all the
2681   // objects on them have been correctly scanned before we start
2682   // moving them during the GC.
2683   bool waited = _cm->root_regions()->wait_until_scan_finished();
2684   double wait_time_ms = 0.0;
2685   if (waited) {
2686     double scan_wait_end = os::elapsedTime();
2687     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2688   }
2689   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2690 }
2691 
2692 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2693 private:
2694   G1HRPrinter* _hr_printer;
2695 public:
2696   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2697 
2698   virtual bool do_heap_region(HeapRegion* r) {
2699     _hr_printer->cset(r);
2700     return false;
2701   }
2702 };
2703 
2704 void G1CollectedHeap::start_new_collection_set() {
2705   collection_set()->start_incremental_building();
2706 
2707   clear_cset_fast_test();
2708 
2709   guarantee(_eden.length() == 0, "eden should have been cleared");
2710   g1_policy()->transfer_survivors_to_cset(survivor());
2711 }
2712 
2713 bool
2714 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2715   assert_at_safepoint_on_vm_thread();
2716   guarantee(!is_gc_active(), "collection is not reentrant");
2717 
2718   if (GCLocker::check_active_before_gc()) {
2719     return false;
2720   }
2721 
2722   _gc_timer_stw->register_gc_start();
2723 
2724   GCIdMark gc_id_mark;
2725   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2726 
2727   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2728   ResourceMark rm;
2729 
2730   g1_policy()->note_gc_start();
2731 
2732   wait_for_root_region_scanning();
2733 
2734   print_heap_before_gc();
2735   print_heap_regions();
2736   trace_heap_before_gc(_gc_tracer_stw);
2737 
2738   _verifier->verify_region_sets_optional();
2739   _verifier->verify_dirty_young_regions();
2740 
2741   // We should not be doing initial mark unless the conc mark thread is running
2742   if (!_cm_thread->should_terminate()) {
2743     // This call will decide whether this pause is an initial-mark
2744     // pause. If it is, in_initial_mark_gc() will return true
2745     // for the duration of this pause.
2746     g1_policy()->decide_on_conc_mark_initiation();
2747   }
2748 
2749   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2750   assert(!collector_state()->in_initial_mark_gc() ||
2751           collector_state()->in_young_only_phase(), "sanity");
2752 
2753   // We also do not allow mixed GCs during marking.
2754   assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2755 
2756   // Record whether this pause is an initial mark. When the current
2757   // thread has completed its logging output and it's safe to signal
2758   // the CM thread, the flag's value in the policy has been reset.
2759   bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2760 
2761   // Inner scope for scope based logging, timers, and stats collection
2762   {
2763     EvacuationInfo evacuation_info;
2764 
2765     if (collector_state()->in_initial_mark_gc()) {
2766       // We are about to start a marking cycle, so we increment the
2767       // full collection counter.
2768       increment_old_marking_cycles_started();
2769       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2770     }
2771 
2772     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2773 
2774     GCTraceCPUTime tcpu;
2775 
2776     G1HeapVerifier::G1VerifyType verify_type;
2777     FormatBuffer<> gc_string("Pause ");
2778     if (collector_state()->in_initial_mark_gc()) {
2779       gc_string.append("Initial Mark");
2780       verify_type = G1HeapVerifier::G1VerifyInitialMark;
2781     } else if (collector_state()->in_young_only_phase()) {
2782       gc_string.append("Young");
2783       verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2784     } else {
2785       gc_string.append("Mixed");
2786       verify_type = G1HeapVerifier::G1VerifyMixed;
2787     }
2788     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2789 
2790     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2791                                                                   workers()->active_workers(),
2792                                                                   Threads::number_of_non_daemon_threads());
2793     active_workers = workers()->update_active_workers(active_workers);
2794     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2795 
2796     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2797     TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2798 
2799     G1HeapTransition heap_transition(this);
2800     size_t heap_used_bytes_before_gc = used();
2801 
2802     // Don't dynamically change the number of GC threads this early.  A value of
2803     // 0 is used to indicate serial work.  When parallel work is done,
2804     // it will be set.
2805 
2806     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2807       IsGCActiveMark x;
2808 
2809       gc_prologue(false);
2810 
2811       if (VerifyRememberedSets) {
2812         log_info(gc, verify)("[Verifying RemSets before GC]");
2813         VerifyRegionRemSetClosure v_cl;
2814         heap_region_iterate(&v_cl);
2815       }
2816 
2817       _verifier->verify_before_gc(verify_type);
2818 
2819       _verifier->check_bitmaps("GC Start");
2820 
2821 #if COMPILER2_OR_JVMCI
2822       DerivedPointerTable::clear();
2823 #endif
2824 
2825       // Please see comment in g1CollectedHeap.hpp and
2826       // G1CollectedHeap::ref_processing_init() to see how
2827       // reference processing currently works in G1.
2828 
2829       // Enable discovery in the STW reference processor
2830       _ref_processor_stw->enable_discovery();
2831 
2832       {
2833         // We want to temporarily turn off discovery by the
2834         // CM ref processor, if necessary, and turn it back on
2835         // on again later if we do. Using a scoped
2836         // NoRefDiscovery object will do this.
2837         NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2838 
2839         // Forget the current alloc region (we might even choose it to be part
2840         // of the collection set!).
2841         _allocator->release_mutator_alloc_region();
2842 
2843         // This timing is only used by the ergonomics to handle our pause target.
2844         // It is unclear why this should not include the full pause. We will
2845         // investigate this in CR 7178365.
2846         //
2847         // Preserving the old comment here if that helps the investigation:
2848         //
2849         // The elapsed time induced by the start time below deliberately elides
2850         // the possible verification above.
2851         double sample_start_time_sec = os::elapsedTime();
2852 
2853         g1_policy()->record_collection_pause_start(sample_start_time_sec);
2854 
2855         if (collector_state()->in_initial_mark_gc()) {
2856           concurrent_mark()->pre_initial_mark();
2857         }
2858 
2859         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2860 
2861         evacuation_info.set_collectionset_regions(collection_set()->region_length());
2862 
2863         // Make sure the remembered sets are up to date. This needs to be
2864         // done before register_humongous_regions_with_cset(), because the
2865         // remembered sets are used there to choose eager reclaim candidates.
2866         // If the remembered sets are not up to date we might miss some
2867         // entries that need to be handled.
2868         g1_rem_set()->cleanupHRRS();
2869 
2870         register_humongous_regions_with_cset();
2871 
2872         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2873 
2874         // We call this after finalize_cset() to
2875         // ensure that the CSet has been finalized.
2876         _cm->verify_no_cset_oops();
2877 
2878         if (_hr_printer.is_active()) {
2879           G1PrintCollectionSetClosure cl(&_hr_printer);
2880           _collection_set.iterate(&cl);
2881         }
2882 
2883         // Initialize the GC alloc regions.
2884         _allocator->init_gc_alloc_regions(evacuation_info);
2885 
2886         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2887         pre_evacuate_collection_set();
2888 
2889         // Actually do the work...
2890         evacuate_collection_set(&per_thread_states);
2891 
2892         post_evacuate_collection_set(evacuation_info, &per_thread_states);
2893 
2894         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
2895         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
2896 
2897         eagerly_reclaim_humongous_regions();
2898 
2899         record_obj_copy_mem_stats();
2900         _survivor_evac_stats.adjust_desired_plab_sz();
2901         _old_evac_stats.adjust_desired_plab_sz();
2902 
2903         double start = os::elapsedTime();
2904         start_new_collection_set();
2905         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2906 
2907         if (evacuation_failed()) {
2908           set_used(recalculate_used());
2909           if (_archive_allocator != NULL) {
2910             _archive_allocator->clear_used();
2911           }
2912           for (uint i = 0; i < ParallelGCThreads; i++) {
2913             if (_evacuation_failed_info_array[i].has_failed()) {
2914               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
2915             }
2916           }
2917         } else {
2918           // The "used" of the the collection set have already been subtracted
2919           // when they were freed.  Add in the bytes evacuated.
2920           increase_used(g1_policy()->bytes_copied_during_gc());
2921         }
2922 
2923         if (collector_state()->in_initial_mark_gc()) {
2924           // We have to do this before we notify the CM threads that
2925           // they can start working to make sure that all the
2926           // appropriate initialization is done on the CM object.
2927           concurrent_mark()->post_initial_mark();
2928           // Note that we don't actually trigger the CM thread at
2929           // this point. We do that later when we're sure that
2930           // the current thread has completed its logging output.
2931         }
2932 
2933         allocate_dummy_regions();
2934 
2935         _allocator->init_mutator_alloc_region();
2936 
2937         {
2938           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2939           if (expand_bytes > 0) {
2940             size_t bytes_before = capacity();
2941             // No need for an ergo logging here,
2942             // expansion_amount() does this when it returns a value > 0.
2943             double expand_ms;
2944             if (!expand(expand_bytes, _workers, &expand_ms)) {
2945               // We failed to expand the heap. Cannot do anything about it.
2946             }
2947             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
2948           }
2949         }
2950 
2951         // We redo the verification but now wrt to the new CSet which
2952         // has just got initialized after the previous CSet was freed.
2953         _cm->verify_no_cset_oops();
2954 
2955         // This timing is only used by the ergonomics to handle our pause target.
2956         // It is unclear why this should not include the full pause. We will
2957         // investigate this in CR 7178365.
2958         double sample_end_time_sec = os::elapsedTime();
2959         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
2960         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
2961         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
2962 
2963         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
2964         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
2965 
2966         if (VerifyRememberedSets) {
2967           log_info(gc, verify)("[Verifying RemSets after GC]");
2968           VerifyRegionRemSetClosure v_cl;
2969           heap_region_iterate(&v_cl);
2970         }
2971 
2972         _verifier->verify_after_gc(verify_type);
2973         _verifier->check_bitmaps("GC End");
2974 
2975         assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
2976         _ref_processor_stw->verify_no_references_recorded();
2977 
2978         // CM reference discovery will be re-enabled if necessary.
2979       }
2980 
2981 #ifdef TRACESPINNING
2982       ParallelTaskTerminator::print_termination_counts();
2983 #endif
2984 
2985       gc_epilogue(false);
2986     }
2987 
2988     // Print the remainder of the GC log output.
2989     if (evacuation_failed()) {
2990       log_info(gc)("To-space exhausted");
2991     }
2992 
2993     g1_policy()->print_phases();
2994     heap_transition.print();
2995 
2996     // It is not yet to safe to tell the concurrent mark to
2997     // start as we have some optional output below. We don't want the
2998     // output from the concurrent mark thread interfering with this
2999     // logging output either.
3000 
3001     _hrm.verify_optional();
3002     _verifier->verify_region_sets_optional();
3003 
3004     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3005     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3006 
3007     print_heap_after_gc();
3008     print_heap_regions();
3009     trace_heap_after_gc(_gc_tracer_stw);
3010 
3011     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3012     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3013     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3014     // before any GC notifications are raised.
3015     g1mm()->update_sizes();
3016 
3017     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3018     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3019     _gc_timer_stw->register_gc_end();
3020     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3021   }
3022   // It should now be safe to tell the concurrent mark thread to start
3023   // without its logging output interfering with the logging output
3024   // that came from the pause.
3025 
3026   if (should_start_conc_mark) {
3027     // CAUTION: after the doConcurrentMark() call below,
3028     // the concurrent marking thread(s) could be running
3029     // concurrently with us. Make sure that anything after
3030     // this point does not assume that we are the only GC thread
3031     // running. Note: of course, the actual marking work will
3032     // not start until the safepoint itself is released in
3033     // SuspendibleThreadSet::desynchronize().
3034     do_concurrent_mark();
3035   }
3036 
3037   return true;
3038 }
3039 
3040 void G1CollectedHeap::remove_self_forwarding_pointers() {
3041   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3042   workers()->run_task(&rsfp_task);
3043 }
3044 
3045 void G1CollectedHeap::restore_after_evac_failure() {
3046   double remove_self_forwards_start = os::elapsedTime();
3047 
3048   remove_self_forwarding_pointers();
3049   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3050   _preserved_marks_set.restore(&task_executor);
3051 
3052   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3053 }
3054 
3055 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3056   if (!_evacuation_failed) {
3057     _evacuation_failed = true;
3058   }
3059 
3060   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3061   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3062 }
3063 
3064 bool G1ParEvacuateFollowersClosure::offer_termination() {
3065   G1ParScanThreadState* const pss = par_scan_state();
3066   start_term_time();
3067   const bool res = terminator()->offer_termination();
3068   end_term_time();
3069   return res;
3070 }
3071 
3072 void G1ParEvacuateFollowersClosure::do_void() {
3073   G1ParScanThreadState* const pss = par_scan_state();
3074   pss->trim_queue();
3075   do {
3076     pss->steal_and_trim_queue(queues());
3077   } while (!offer_termination());
3078 }
3079 
3080 class G1ParTask : public AbstractGangTask {
3081 protected:
3082   G1CollectedHeap*         _g1h;
3083   G1ParScanThreadStateSet* _pss;
3084   RefToScanQueueSet*       _queues;
3085   G1RootProcessor*         _root_processor;
3086   ParallelTaskTerminator   _terminator;
3087   uint                     _n_workers;
3088 
3089 public:
3090   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3091     : AbstractGangTask("G1 collection"),
3092       _g1h(g1h),
3093       _pss(per_thread_states),
3094       _queues(task_queues),
3095       _root_processor(root_processor),
3096       _terminator(n_workers, _queues),
3097       _n_workers(n_workers)
3098   {}
3099 
3100   void work(uint worker_id) {
3101     if (worker_id >= _n_workers) return;  // no work needed this round
3102 
3103     double start_sec = os::elapsedTime();
3104     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3105 
3106     {
3107       ResourceMark rm;
3108       HandleMark   hm;
3109 
3110       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3111 
3112       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3113       pss->set_ref_processor(rp);
3114 
3115       double start_strong_roots_sec = os::elapsedTime();
3116 
3117       _root_processor->evacuate_roots(pss, worker_id);
3118 
3119       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3120       // treating the nmethods visited to act as roots for concurrent marking.
3121       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3122       // objects copied by the current evacuation.
3123       _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3124 
3125       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3126 
3127       double term_sec = 0.0;
3128       size_t evac_term_attempts = 0;
3129       {
3130         double start = os::elapsedTime();
3131         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3132         evac.do_void();
3133 
3134         evac_term_attempts = evac.term_attempts();
3135         term_sec = evac.term_time();
3136         double elapsed_sec = os::elapsedTime() - start;
3137 
3138         G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3139         p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3140         p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3141         p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3142       }
3143 
3144       assert(pss->queue_is_empty(), "should be empty");
3145 
3146       if (log_is_enabled(Debug, gc, task, stats)) {
3147         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3148         size_t lab_waste;
3149         size_t lab_undo_waste;
3150         pss->waste(lab_waste, lab_undo_waste);
3151         _g1h->print_termination_stats(worker_id,
3152                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3153                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3154                                       term_sec * 1000.0,                          /* evac term time */
3155                                       evac_term_attempts,                         /* evac term attempts */
3156                                       lab_waste,                                  /* alloc buffer waste */
3157                                       lab_undo_waste                              /* undo waste */
3158                                       );
3159       }
3160 
3161       // Close the inner scope so that the ResourceMark and HandleMark
3162       // destructors are executed here and are included as part of the
3163       // "GC Worker Time".
3164     }
3165     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3166   }
3167 };
3168 
3169 void G1CollectedHeap::print_termination_stats_hdr() {
3170   log_debug(gc, task, stats)("GC Termination Stats");
3171   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3172   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3173   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3174 }
3175 
3176 void G1CollectedHeap::print_termination_stats(uint worker_id,
3177                                               double elapsed_ms,
3178                                               double strong_roots_ms,
3179                                               double term_ms,
3180                                               size_t term_attempts,
3181                                               size_t alloc_buffer_waste,
3182                                               size_t undo_waste) const {
3183   log_debug(gc, task, stats)
3184               ("%3d %9.2f %9.2f %6.2f "
3185                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3186                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3187                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3188                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3189                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3190                alloc_buffer_waste * HeapWordSize / K,
3191                undo_waste * HeapWordSize / K);
3192 }
3193 
3194 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3195 private:
3196   BoolObjectClosure* _is_alive;
3197   G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3198 
3199   int _initial_string_table_size;
3200   int _initial_symbol_table_size;
3201 
3202   bool  _process_strings;
3203   int _strings_processed;
3204   int _strings_removed;
3205 
3206   bool  _process_symbols;
3207   int _symbols_processed;
3208   int _symbols_removed;
3209 
3210   bool _process_string_dedup;
3211 
3212 public:
3213   G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3214     AbstractGangTask("String/Symbol Unlinking"),
3215     _is_alive(is_alive),
3216     _dedup_closure(is_alive, NULL, false),
3217     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3218     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3219     _process_string_dedup(process_string_dedup) {
3220 
3221     _initial_string_table_size = StringTable::the_table()->table_size();
3222     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3223     if (process_strings) {
3224       StringTable::clear_parallel_claimed_index();
3225     }
3226     if (process_symbols) {
3227       SymbolTable::clear_parallel_claimed_index();
3228     }
3229   }
3230 
3231   ~G1StringAndSymbolCleaningTask() {
3232     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3233               "claim value %d after unlink less than initial string table size %d",
3234               StringTable::parallel_claimed_index(), _initial_string_table_size);
3235     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3236               "claim value %d after unlink less than initial symbol table size %d",
3237               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3238 
3239     log_info(gc, stringtable)(
3240         "Cleaned string and symbol table, "
3241         "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3242         "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3243         strings_processed(), strings_removed(),
3244         symbols_processed(), symbols_removed());
3245   }
3246 
3247   void work(uint worker_id) {
3248     int strings_processed = 0;
3249     int strings_removed = 0;
3250     int symbols_processed = 0;
3251     int symbols_removed = 0;
3252     if (_process_strings) {
3253       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3254       Atomic::add(strings_processed, &_strings_processed);
3255       Atomic::add(strings_removed, &_strings_removed);
3256     }
3257     if (_process_symbols) {
3258       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3259       Atomic::add(symbols_processed, &_symbols_processed);
3260       Atomic::add(symbols_removed, &_symbols_removed);
3261     }
3262     if (_process_string_dedup) {
3263       G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3264     }
3265   }
3266 
3267   size_t strings_processed() const { return (size_t)_strings_processed; }
3268   size_t strings_removed()   const { return (size_t)_strings_removed; }
3269 
3270   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3271   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3272 };
3273 
3274 class G1CodeCacheUnloadingTask {
3275 private:
3276   static Monitor* _lock;
3277 
3278   BoolObjectClosure* const _is_alive;
3279   const bool               _unloading_occurred;
3280   const uint               _num_workers;
3281 
3282   // Variables used to claim nmethods.
3283   CompiledMethod* _first_nmethod;
3284   CompiledMethod* volatile _claimed_nmethod;
3285 
3286   // The list of nmethods that need to be processed by the second pass.
3287   CompiledMethod* volatile _postponed_list;
3288   volatile uint            _num_entered_barrier;
3289 
3290  public:
3291   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3292       _is_alive(is_alive),
3293       _unloading_occurred(unloading_occurred),
3294       _num_workers(num_workers),
3295       _first_nmethod(NULL),
3296       _claimed_nmethod(NULL),
3297       _postponed_list(NULL),
3298       _num_entered_barrier(0)
3299   {
3300     CompiledMethod::increase_unloading_clock();
3301     // Get first alive nmethod
3302     CompiledMethodIterator iter = CompiledMethodIterator();
3303     if(iter.next_alive()) {
3304       _first_nmethod = iter.method();
3305     }
3306     _claimed_nmethod = _first_nmethod;
3307   }
3308 
3309   ~G1CodeCacheUnloadingTask() {
3310     CodeCache::verify_clean_inline_caches();
3311 
3312     CodeCache::set_needs_cache_clean(false);
3313     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3314 
3315     CodeCache::verify_icholder_relocations();
3316   }
3317 
3318  private:
3319   void add_to_postponed_list(CompiledMethod* nm) {
3320       CompiledMethod* old;
3321       do {
3322         old = _postponed_list;
3323         nm->set_unloading_next(old);
3324       } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3325   }
3326 
3327   void clean_nmethod(CompiledMethod* nm) {
3328     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3329 
3330     if (postponed) {
3331       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3332       add_to_postponed_list(nm);
3333     }
3334 
3335     // Mark that this thread has been cleaned/unloaded.
3336     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3337     nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3338   }
3339 
3340   void clean_nmethod_postponed(CompiledMethod* nm) {
3341     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3342   }
3343 
3344   static const int MaxClaimNmethods = 16;
3345 
3346   void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3347     CompiledMethod* first;
3348     CompiledMethodIterator last;
3349 
3350     do {
3351       *num_claimed_nmethods = 0;
3352 
3353       first = _claimed_nmethod;
3354       last = CompiledMethodIterator(first);
3355 
3356       if (first != NULL) {
3357 
3358         for (int i = 0; i < MaxClaimNmethods; i++) {
3359           if (!last.next_alive()) {
3360             break;
3361           }
3362           claimed_nmethods[i] = last.method();
3363           (*num_claimed_nmethods)++;
3364         }
3365       }
3366 
3367     } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3368   }
3369 
3370   CompiledMethod* claim_postponed_nmethod() {
3371     CompiledMethod* claim;
3372     CompiledMethod* next;
3373 
3374     do {
3375       claim = _postponed_list;
3376       if (claim == NULL) {
3377         return NULL;
3378       }
3379 
3380       next = claim->unloading_next();
3381 
3382     } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3383 
3384     return claim;
3385   }
3386 
3387  public:
3388   // Mark that we're done with the first pass of nmethod cleaning.
3389   void barrier_mark(uint worker_id) {
3390     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3391     _num_entered_barrier++;
3392     if (_num_entered_barrier == _num_workers) {
3393       ml.notify_all();
3394     }
3395   }
3396 
3397   // See if we have to wait for the other workers to
3398   // finish their first-pass nmethod cleaning work.
3399   void barrier_wait(uint worker_id) {
3400     if (_num_entered_barrier < _num_workers) {
3401       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3402       while (_num_entered_barrier < _num_workers) {
3403           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3404       }
3405     }
3406   }
3407 
3408   // Cleaning and unloading of nmethods. Some work has to be postponed
3409   // to the second pass, when we know which nmethods survive.
3410   void work_first_pass(uint worker_id) {
3411     // The first nmethods is claimed by the first worker.
3412     if (worker_id == 0 && _first_nmethod != NULL) {
3413       clean_nmethod(_first_nmethod);
3414       _first_nmethod = NULL;
3415     }
3416 
3417     int num_claimed_nmethods;
3418     CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3419 
3420     while (true) {
3421       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3422 
3423       if (num_claimed_nmethods == 0) {
3424         break;
3425       }
3426 
3427       for (int i = 0; i < num_claimed_nmethods; i++) {
3428         clean_nmethod(claimed_nmethods[i]);
3429       }
3430     }
3431   }
3432 
3433   void work_second_pass(uint worker_id) {
3434     CompiledMethod* nm;
3435     // Take care of postponed nmethods.
3436     while ((nm = claim_postponed_nmethod()) != NULL) {
3437       clean_nmethod_postponed(nm);
3438     }
3439   }
3440 };
3441 
3442 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3443 
3444 class G1KlassCleaningTask : public StackObj {
3445   volatile int                            _clean_klass_tree_claimed;
3446   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3447 
3448  public:
3449   G1KlassCleaningTask() :
3450       _clean_klass_tree_claimed(0),
3451       _klass_iterator() {
3452   }
3453 
3454  private:
3455   bool claim_clean_klass_tree_task() {
3456     if (_clean_klass_tree_claimed) {
3457       return false;
3458     }
3459 
3460     return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3461   }
3462 
3463   InstanceKlass* claim_next_klass() {
3464     Klass* klass;
3465     do {
3466       klass =_klass_iterator.next_klass();
3467     } while (klass != NULL && !klass->is_instance_klass());
3468 
3469     // this can be null so don't call InstanceKlass::cast
3470     return static_cast<InstanceKlass*>(klass);
3471   }
3472 
3473 public:
3474 
3475   void clean_klass(InstanceKlass* ik) {
3476     ik->clean_weak_instanceklass_links();
3477   }
3478 
3479   void work() {
3480     ResourceMark rm;
3481 
3482     // One worker will clean the subklass/sibling klass tree.
3483     if (claim_clean_klass_tree_task()) {
3484       Klass::clean_subklass_tree();
3485     }
3486 
3487     // All workers will help cleaning the classes,
3488     InstanceKlass* klass;
3489     while ((klass = claim_next_klass()) != NULL) {
3490       clean_klass(klass);
3491     }
3492   }
3493 };
3494 
3495 class G1ResolvedMethodCleaningTask : public StackObj {
3496   volatile int       _resolved_method_task_claimed;
3497 public:
3498   G1ResolvedMethodCleaningTask() :
3499       _resolved_method_task_claimed(0) {}
3500 
3501   bool claim_resolved_method_task() {
3502     if (_resolved_method_task_claimed) {
3503       return false;
3504     }
3505     return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3506   }
3507 
3508   // These aren't big, one thread can do it all.
3509   void work() {
3510     if (claim_resolved_method_task()) {
3511       ResolvedMethodTable::unlink();
3512     }
3513   }
3514 };
3515 
3516 
3517 // To minimize the remark pause times, the tasks below are done in parallel.
3518 class G1ParallelCleaningTask : public AbstractGangTask {
3519 private:
3520   G1StringAndSymbolCleaningTask _string_symbol_task;
3521   G1CodeCacheUnloadingTask      _code_cache_task;
3522   G1KlassCleaningTask           _klass_cleaning_task;
3523   G1ResolvedMethodCleaningTask  _resolved_method_cleaning_task;
3524 
3525 public:
3526   // The constructor is run in the VMThread.
3527   G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3528       AbstractGangTask("Parallel Cleaning"),
3529       _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3530       _code_cache_task(num_workers, is_alive, unloading_occurred),
3531       _klass_cleaning_task(),
3532       _resolved_method_cleaning_task() {
3533   }
3534 
3535   // The parallel work done by all worker threads.
3536   void work(uint worker_id) {
3537     // Do first pass of code cache cleaning.
3538     _code_cache_task.work_first_pass(worker_id);
3539 
3540     // Let the threads mark that the first pass is done.
3541     _code_cache_task.barrier_mark(worker_id);
3542 
3543     // Clean the Strings and Symbols.
3544     _string_symbol_task.work(worker_id);
3545 
3546     // Clean unreferenced things in the ResolvedMethodTable
3547     _resolved_method_cleaning_task.work();
3548 
3549     // Wait for all workers to finish the first code cache cleaning pass.
3550     _code_cache_task.barrier_wait(worker_id);
3551 
3552     // Do the second code cache cleaning work, which realize on
3553     // the liveness information gathered during the first pass.
3554     _code_cache_task.work_second_pass(worker_id);
3555 
3556     // Clean all klasses that were not unloaded.
3557     _klass_cleaning_task.work();
3558   }
3559 };
3560 
3561 
3562 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3563                                         bool class_unloading_occurred) {
3564   uint n_workers = workers()->active_workers();
3565 
3566   G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3567   workers()->run_task(&g1_unlink_task);
3568 }
3569 
3570 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3571                                        bool process_strings,
3572                                        bool process_symbols,
3573                                        bool process_string_dedup) {
3574   if (!process_strings && !process_symbols && !process_string_dedup) {
3575     // Nothing to clean.
3576     return;
3577   }
3578 
3579   G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3580   workers()->run_task(&g1_unlink_task);
3581 
3582 }
3583 
3584 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3585  private:
3586   DirtyCardQueueSet* _queue;
3587   G1CollectedHeap* _g1h;
3588  public:
3589   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3590     _queue(queue), _g1h(g1h) { }
3591 
3592   virtual void work(uint worker_id) {
3593     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3594     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3595 
3596     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3597     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3598 
3599     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3600   }
3601 };
3602 
3603 void G1CollectedHeap::redirty_logged_cards() {
3604   double redirty_logged_cards_start = os::elapsedTime();
3605 
3606   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3607   dirty_card_queue_set().reset_for_par_iteration();
3608   workers()->run_task(&redirty_task);
3609 
3610   DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3611   dcq.merge_bufferlists(&dirty_card_queue_set());
3612   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3613 
3614   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3615 }
3616 
3617 // Weak Reference Processing support
3618 
3619 bool G1STWIsAliveClosure::do_object_b(oop p) {
3620   // An object is reachable if it is outside the collection set,
3621   // or is inside and copied.
3622   return !_g1h->is_in_cset(p) || p->is_forwarded();
3623 }
3624 
3625 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3626   assert(obj != NULL, "must not be NULL");
3627   assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3628   // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3629   // may falsely indicate that this is not the case here: however the collection set only
3630   // contains old regions when concurrent mark is not running.
3631   return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3632 }
3633 
3634 // Non Copying Keep Alive closure
3635 class G1KeepAliveClosure: public OopClosure {
3636   G1CollectedHeap*_g1h;
3637 public:
3638   G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3639   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3640   void do_oop(oop* p) {
3641     oop obj = *p;
3642     assert(obj != NULL, "the caller should have filtered out NULL values");
3643 
3644     const InCSetState cset_state =_g1h->in_cset_state(obj);
3645     if (!cset_state.is_in_cset_or_humongous()) {
3646       return;
3647     }
3648     if (cset_state.is_in_cset()) {
3649       assert( obj->is_forwarded(), "invariant" );
3650       *p = obj->forwardee();
3651     } else {
3652       assert(!obj->is_forwarded(), "invariant" );
3653       assert(cset_state.is_humongous(),
3654              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3655      _g1h->set_humongous_is_live(obj);
3656     }
3657   }
3658 };
3659 
3660 // Copying Keep Alive closure - can be called from both
3661 // serial and parallel code as long as different worker
3662 // threads utilize different G1ParScanThreadState instances
3663 // and different queues.
3664 
3665 class G1CopyingKeepAliveClosure: public OopClosure {
3666   G1CollectedHeap*         _g1h;
3667   OopClosure*              _copy_non_heap_obj_cl;
3668   G1ParScanThreadState*    _par_scan_state;
3669 
3670 public:
3671   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3672                             OopClosure* non_heap_obj_cl,
3673                             G1ParScanThreadState* pss):
3674     _g1h(g1h),
3675     _copy_non_heap_obj_cl(non_heap_obj_cl),
3676     _par_scan_state(pss)
3677   {}
3678 
3679   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3680   virtual void do_oop(      oop* p) { do_oop_work(p); }
3681 
3682   template <class T> void do_oop_work(T* p) {
3683     oop obj = RawAccess<>::oop_load(p);
3684 
3685     if (_g1h->is_in_cset_or_humongous(obj)) {
3686       // If the referent object has been forwarded (either copied
3687       // to a new location or to itself in the event of an
3688       // evacuation failure) then we need to update the reference
3689       // field and, if both reference and referent are in the G1
3690       // heap, update the RSet for the referent.
3691       //
3692       // If the referent has not been forwarded then we have to keep
3693       // it alive by policy. Therefore we have copy the referent.
3694       //
3695       // If the reference field is in the G1 heap then we can push
3696       // on the PSS queue. When the queue is drained (after each
3697       // phase of reference processing) the object and it's followers
3698       // will be copied, the reference field set to point to the
3699       // new location, and the RSet updated. Otherwise we need to
3700       // use the the non-heap or metadata closures directly to copy
3701       // the referent object and update the pointer, while avoiding
3702       // updating the RSet.
3703 
3704       if (_g1h->is_in_g1_reserved(p)) {
3705         _par_scan_state->push_on_queue(p);
3706       } else {
3707         assert(!Metaspace::contains((const void*)p),
3708                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3709         _copy_non_heap_obj_cl->do_oop(p);
3710       }
3711     }
3712   }
3713 };
3714 
3715 // Serial drain queue closure. Called as the 'complete_gc'
3716 // closure for each discovered list in some of the
3717 // reference processing phases.
3718 
3719 class G1STWDrainQueueClosure: public VoidClosure {
3720 protected:
3721   G1CollectedHeap* _g1h;
3722   G1ParScanThreadState* _par_scan_state;
3723 
3724   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3725 
3726 public:
3727   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3728     _g1h(g1h),
3729     _par_scan_state(pss)
3730   { }
3731 
3732   void do_void() {
3733     G1ParScanThreadState* const pss = par_scan_state();
3734     pss->trim_queue();
3735   }
3736 };
3737 
3738 // Parallel Reference Processing closures
3739 
3740 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3741 // processing during G1 evacuation pauses.
3742 
3743 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3744 private:
3745   G1CollectedHeap*          _g1h;
3746   G1ParScanThreadStateSet*  _pss;
3747   RefToScanQueueSet*        _queues;
3748   WorkGang*                 _workers;
3749   uint                      _active_workers;
3750 
3751 public:
3752   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3753                            G1ParScanThreadStateSet* per_thread_states,
3754                            WorkGang* workers,
3755                            RefToScanQueueSet *task_queues,
3756                            uint n_workers) :
3757     _g1h(g1h),
3758     _pss(per_thread_states),
3759     _queues(task_queues),
3760     _workers(workers),
3761     _active_workers(n_workers)
3762   {
3763     g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3764   }
3765 
3766   // Executes the given task using concurrent marking worker threads.
3767   virtual void execute(ProcessTask& task);
3768   virtual void execute(EnqueueTask& task);
3769 };
3770 
3771 // Gang task for possibly parallel reference processing
3772 
3773 class G1STWRefProcTaskProxy: public AbstractGangTask {
3774   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3775   ProcessTask&     _proc_task;
3776   G1CollectedHeap* _g1h;
3777   G1ParScanThreadStateSet* _pss;
3778   RefToScanQueueSet* _task_queues;
3779   ParallelTaskTerminator* _terminator;
3780 
3781 public:
3782   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3783                         G1CollectedHeap* g1h,
3784                         G1ParScanThreadStateSet* per_thread_states,
3785                         RefToScanQueueSet *task_queues,
3786                         ParallelTaskTerminator* terminator) :
3787     AbstractGangTask("Process reference objects in parallel"),
3788     _proc_task(proc_task),
3789     _g1h(g1h),
3790     _pss(per_thread_states),
3791     _task_queues(task_queues),
3792     _terminator(terminator)
3793   {}
3794 
3795   virtual void work(uint worker_id) {
3796     // The reference processing task executed by a single worker.
3797     ResourceMark rm;
3798     HandleMark   hm;
3799 
3800     G1STWIsAliveClosure is_alive(_g1h);
3801 
3802     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
3803     pss->set_ref_processor(NULL);
3804 
3805     // Keep alive closure.
3806     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3807 
3808     // Complete GC closure
3809     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3810 
3811     // Call the reference processing task's work routine.
3812     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3813 
3814     // Note we cannot assert that the refs array is empty here as not all
3815     // of the processing tasks (specifically phase2 - pp2_work) execute
3816     // the complete_gc closure (which ordinarily would drain the queue) so
3817     // the queue may not be empty.
3818   }
3819 };
3820 
3821 // Driver routine for parallel reference processing.
3822 // Creates an instance of the ref processing gang
3823 // task and has the worker threads execute it.
3824 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3825   assert(_workers != NULL, "Need parallel worker threads.");
3826 
3827   ParallelTaskTerminator terminator(_active_workers, _queues);
3828   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3829 
3830   _workers->run_task(&proc_task_proxy);
3831 }
3832 
3833 // Gang task for parallel reference enqueueing.
3834 
3835 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
3836   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
3837   EnqueueTask& _enq_task;
3838 
3839 public:
3840   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
3841     AbstractGangTask("Enqueue reference objects in parallel"),
3842     _enq_task(enq_task)
3843   { }
3844 
3845   virtual void work(uint worker_id) {
3846     _enq_task.work(worker_id);
3847   }
3848 };
3849 
3850 // Driver routine for parallel reference enqueueing.
3851 // Creates an instance of the ref enqueueing gang
3852 // task and has the worker threads execute it.
3853 
3854 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
3855   assert(_workers != NULL, "Need parallel worker threads.");
3856 
3857   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
3858 
3859   _workers->run_task(&enq_task_proxy);
3860 }
3861 
3862 // End of weak reference support closures
3863 
3864 // Weak Reference processing during an evacuation pause (part 1).
3865 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3866   double ref_proc_start = os::elapsedTime();
3867 
3868   ReferenceProcessor* rp = _ref_processor_stw;
3869   assert(rp->discovery_enabled(), "should have been enabled");
3870 
3871   // Closure to test whether a referent is alive.
3872   G1STWIsAliveClosure is_alive(this);
3873 
3874   // Even when parallel reference processing is enabled, the processing
3875   // of JNI refs is serial and performed serially by the current thread
3876   // rather than by a worker. The following PSS will be used for processing
3877   // JNI refs.
3878 
3879   // Use only a single queue for this PSS.
3880   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
3881   pss->set_ref_processor(NULL);
3882   assert(pss->queue_is_empty(), "pre-condition");
3883 
3884   // Keep alive closure.
3885   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
3886 
3887   // Serial Complete GC closure
3888   G1STWDrainQueueClosure drain_queue(this, pss);
3889 
3890   // Setup the soft refs policy...
3891   rp->setup_policy(false);
3892 
3893   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3894 
3895   ReferenceProcessorStats stats;
3896   if (!rp->processing_is_mt()) {
3897     // Serial reference processing...
3898     stats = rp->process_discovered_references(&is_alive,
3899                                               &keep_alive,
3900                                               &drain_queue,
3901                                               NULL,
3902                                               pt);
3903   } else {
3904     uint no_of_gc_workers = workers()->active_workers();
3905 
3906     // Parallel reference processing
3907     assert(no_of_gc_workers <= rp->max_num_q(),
3908            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3909            no_of_gc_workers,  rp->max_num_q());
3910 
3911     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
3912     stats = rp->process_discovered_references(&is_alive,
3913                                               &keep_alive,
3914                                               &drain_queue,
3915                                               &par_task_executor,
3916                                               pt);
3917   }
3918 
3919   _gc_tracer_stw->report_gc_reference_stats(stats);
3920 
3921   // We have completed copying any necessary live referent objects.
3922   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3923 
3924   double ref_proc_time = os::elapsedTime() - ref_proc_start;
3925   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3926 }
3927 
3928 // Weak Reference processing during an evacuation pause (part 2).
3929 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3930   double ref_enq_start = os::elapsedTime();
3931 
3932   ReferenceProcessor* rp = _ref_processor_stw;
3933   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
3934 
3935   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3936 
3937   // Now enqueue any remaining on the discovered lists on to
3938   // the pending list.
3939   if (!rp->processing_is_mt()) {
3940     // Serial reference processing...
3941     rp->enqueue_discovered_references(NULL, pt);
3942   } else {
3943     // Parallel reference enqueueing
3944 
3945     uint n_workers = workers()->active_workers();
3946 
3947     assert(n_workers <= rp->max_num_q(),
3948            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3949            n_workers,  rp->max_num_q());
3950 
3951     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
3952     rp->enqueue_discovered_references(&par_task_executor, pt);
3953   }
3954 
3955   rp->verify_no_references_recorded();
3956   assert(!rp->discovery_enabled(), "should have been disabled");
3957 
3958   // If during an initial mark pause we install a pending list head which is not otherwise reachable
3959   // ensure that it is marked in the bitmap for concurrent marking to discover.
3960   if (collector_state()->in_initial_mark_gc()) {
3961     oop pll_head = Universe::reference_pending_list();
3962     if (pll_head != NULL) {
3963       // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3964       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3965     }
3966   }
3967 
3968   // FIXME
3969   // CM's reference processing also cleans up the string and symbol tables.
3970   // Should we do that here also? We could, but it is a serial operation
3971   // and could significantly increase the pause time.
3972 
3973   double ref_enq_time = os::elapsedTime() - ref_enq_start;
3974   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
3975 }
3976 
3977 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3978   double merge_pss_time_start = os::elapsedTime();
3979   per_thread_states->flush();
3980   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3981 }
3982 
3983 void G1CollectedHeap::pre_evacuate_collection_set() {
3984   _expand_heap_after_alloc_failure = true;
3985   _evacuation_failed = false;
3986 
3987   // Disable the hot card cache.
3988   _hot_card_cache->reset_hot_cache_claimed_index();
3989   _hot_card_cache->set_use_cache(false);
3990 
3991   g1_rem_set()->prepare_for_oops_into_collection_set_do();
3992   _preserved_marks_set.assert_empty();
3993 
3994   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3995 
3996   // InitialMark needs claim bits to keep track of the marked-through CLDs.
3997   if (collector_state()->in_initial_mark_gc()) {
3998     double start_clear_claimed_marks = os::elapsedTime();
3999 
4000     ClassLoaderDataGraph::clear_claimed_marks();
4001 
4002     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4003     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4004   }
4005 }
4006 
4007 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
4008   // Should G1EvacuationFailureALot be in effect for this GC?
4009   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4010 
4011   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4012 
4013   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4014 
4015   double start_par_time_sec = os::elapsedTime();
4016   double end_par_time_sec;
4017 
4018   {
4019     const uint n_workers = workers()->active_workers();
4020     G1RootProcessor root_processor(this, n_workers);
4021     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4022 
4023     print_termination_stats_hdr();
4024 
4025     workers()->run_task(&g1_par_task);
4026     end_par_time_sec = os::elapsedTime();
4027 
4028     // Closing the inner scope will execute the destructor
4029     // for the G1RootProcessor object. We record the current
4030     // elapsed time before closing the scope so that time
4031     // taken for the destructor is NOT included in the
4032     // reported parallel time.
4033   }
4034 
4035   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4036   phase_times->record_par_time(par_time_ms);
4037 
4038   double code_root_fixup_time_ms =
4039         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4040   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4041 }
4042 
4043 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4044   // Also cleans the card table from temporary duplicate detection information used
4045   // during UpdateRS/ScanRS.
4046   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4047 
4048   // Process any discovered reference objects - we have
4049   // to do this _before_ we retire the GC alloc regions
4050   // as we may have to copy some 'reachable' referent
4051   // objects (and their reachable sub-graphs) that were
4052   // not copied during the pause.
4053   process_discovered_references(per_thread_states);
4054   enqueue_discovered_references(per_thread_states);
4055 
4056   G1STWIsAliveClosure is_alive(this);
4057   G1KeepAliveClosure keep_alive(this);
4058 
4059   {
4060     double start = os::elapsedTime();
4061 
4062     WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4063 
4064     double time_ms = (os::elapsedTime() - start) * 1000.0;
4065     g1_policy()->phase_times()->record_weak_ref_proc_time(time_ms);
4066   }
4067 
4068   if (G1StringDedup::is_enabled()) {
4069     double fixup_start = os::elapsedTime();
4070 
4071     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4072 
4073     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4074     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4075   }
4076 
4077   if (evacuation_failed()) {
4078     restore_after_evac_failure();
4079 
4080     // Reset the G1EvacuationFailureALot counters and flags
4081     // Note: the values are reset only when an actual
4082     // evacuation failure occurs.
4083     NOT_PRODUCT(reset_evacuation_should_fail();)
4084   }
4085 
4086   _preserved_marks_set.assert_empty();
4087 
4088   _allocator->release_gc_alloc_regions(evacuation_info);
4089 
4090   merge_per_thread_state_info(per_thread_states);
4091 
4092   // Reset and re-enable the hot card cache.
4093   // Note the counts for the cards in the regions in the
4094   // collection set are reset when the collection set is freed.
4095   _hot_card_cache->reset_hot_cache();
4096   _hot_card_cache->set_use_cache(true);
4097 
4098   purge_code_root_memory();
4099 
4100   redirty_logged_cards();
4101 #if COMPILER2_OR_JVMCI
4102   double start = os::elapsedTime();
4103   DerivedPointerTable::update_pointers();
4104   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4105 #endif
4106   g1_policy()->print_age_table();
4107 }
4108 
4109 void G1CollectedHeap::record_obj_copy_mem_stats() {
4110   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4111 
4112   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4113                                                create_g1_evac_summary(&_old_evac_stats));
4114 }
4115 
4116 void G1CollectedHeap::free_region(HeapRegion* hr,
4117                                   FreeRegionList* free_list,
4118                                   bool skip_remset,
4119                                   bool skip_hot_card_cache,
4120                                   bool locked) {
4121   assert(!hr->is_free(), "the region should not be free");
4122   assert(!hr->is_empty(), "the region should not be empty");
4123   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4124   assert(free_list != NULL, "pre-condition");
4125 
4126   if (G1VerifyBitmaps) {
4127     MemRegion mr(hr->bottom(), hr->end());
4128     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4129   }
4130 
4131   // Clear the card counts for this region.
4132   // Note: we only need to do this if the region is not young
4133   // (since we don't refine cards in young regions).
4134   if (!skip_hot_card_cache && !hr->is_young()) {
4135     _hot_card_cache->reset_card_counts(hr);
4136   }
4137   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4138   _g1_policy->remset_tracker()->update_at_free(hr);
4139   free_list->add_ordered(hr);
4140 }
4141 
4142 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4143                                             FreeRegionList* free_list) {
4144   assert(hr->is_humongous(), "this is only for humongous regions");
4145   assert(free_list != NULL, "pre-condition");
4146   hr->clear_humongous();
4147   free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4148 }
4149 
4150 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4151                                            const uint humongous_regions_removed) {
4152   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4153     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4154     _old_set.bulk_remove(old_regions_removed);
4155     _humongous_set.bulk_remove(humongous_regions_removed);
4156   }
4157 
4158 }
4159 
4160 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4161   assert(list != NULL, "list can't be null");
4162   if (!list->is_empty()) {
4163     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4164     _hrm.insert_list_into_free_list(list);
4165   }
4166 }
4167 
4168 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4169   decrease_used(bytes);
4170 }
4171 
4172 class G1FreeCollectionSetTask : public AbstractGangTask {
4173 private:
4174 
4175   // Closure applied to all regions in the collection set to do work that needs to
4176   // be done serially in a single thread.
4177   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4178   private:
4179     EvacuationInfo* _evacuation_info;
4180     const size_t* _surviving_young_words;
4181 
4182     // Bytes used in successfully evacuated regions before the evacuation.
4183     size_t _before_used_bytes;
4184     // Bytes used in unsucessfully evacuated regions before the evacuation
4185     size_t _after_used_bytes;
4186 
4187     size_t _bytes_allocated_in_old_since_last_gc;
4188 
4189     size_t _failure_used_words;
4190     size_t _failure_waste_words;
4191 
4192     FreeRegionList _local_free_list;
4193   public:
4194     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4195       HeapRegionClosure(),
4196       _evacuation_info(evacuation_info),
4197       _surviving_young_words(surviving_young_words),
4198       _before_used_bytes(0),
4199       _after_used_bytes(0),
4200       _bytes_allocated_in_old_since_last_gc(0),
4201       _failure_used_words(0),
4202       _failure_waste_words(0),
4203       _local_free_list("Local Region List for CSet Freeing") {
4204     }
4205 
4206     virtual bool do_heap_region(HeapRegion* r) {
4207       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4208 
4209       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4210       g1h->clear_in_cset(r);
4211 
4212       if (r->is_young()) {
4213         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4214                "Young index %d is wrong for region %u of type %s with %u young regions",
4215                r->young_index_in_cset(),
4216                r->hrm_index(),
4217                r->get_type_str(),
4218                g1h->collection_set()->young_region_length());
4219         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4220         r->record_surv_words_in_group(words_survived);
4221       }
4222 
4223       if (!r->evacuation_failed()) {
4224         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4225         _before_used_bytes += r->used();
4226         g1h->free_region(r,
4227                          &_local_free_list,
4228                          true, /* skip_remset */
4229                          true, /* skip_hot_card_cache */
4230                          true  /* locked */);
4231       } else {
4232         r->uninstall_surv_rate_group();
4233         r->set_young_index_in_cset(-1);
4234         r->set_evacuation_failed(false);
4235         // When moving a young gen region to old gen, we "allocate" that whole region
4236         // there. This is in addition to any already evacuated objects. Notify the
4237         // policy about that.
4238         // Old gen regions do not cause an additional allocation: both the objects
4239         // still in the region and the ones already moved are accounted for elsewhere.
4240         if (r->is_young()) {
4241           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4242         }
4243         // The region is now considered to be old.
4244         r->set_old();
4245         // Do some allocation statistics accounting. Regions that failed evacuation
4246         // are always made old, so there is no need to update anything in the young
4247         // gen statistics, but we need to update old gen statistics.
4248         size_t used_words = r->marked_bytes() / HeapWordSize;
4249 
4250         _failure_used_words += used_words;
4251         _failure_waste_words += HeapRegion::GrainWords - used_words;
4252 
4253         g1h->old_set_add(r);
4254         _after_used_bytes += r->used();
4255       }
4256       return false;
4257     }
4258 
4259     void complete_work() {
4260       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4261 
4262       _evacuation_info->set_regions_freed(_local_free_list.length());
4263       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4264 
4265       g1h->prepend_to_freelist(&_local_free_list);
4266       g1h->decrement_summary_bytes(_before_used_bytes);
4267 
4268       G1Policy* policy = g1h->g1_policy();
4269       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4270 
4271       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4272     }
4273   };
4274 
4275   G1CollectionSet* _collection_set;
4276   G1SerialFreeCollectionSetClosure _cl;
4277   const size_t* _surviving_young_words;
4278 
4279   size_t _rs_lengths;
4280 
4281   volatile jint _serial_work_claim;
4282 
4283   struct WorkItem {
4284     uint region_idx;
4285     bool is_young;
4286     bool evacuation_failed;
4287 
4288     WorkItem(HeapRegion* r) {
4289       region_idx = r->hrm_index();
4290       is_young = r->is_young();
4291       evacuation_failed = r->evacuation_failed();
4292     }
4293   };
4294 
4295   volatile size_t _parallel_work_claim;
4296   size_t _num_work_items;
4297   WorkItem* _work_items;
4298 
4299   void do_serial_work() {
4300     // Need to grab the lock to be allowed to modify the old region list.
4301     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4302     _collection_set->iterate(&_cl);
4303   }
4304 
4305   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4306     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4307 
4308     HeapRegion* r = g1h->region_at(region_idx);
4309     assert(!g1h->is_on_master_free_list(r), "sanity");
4310 
4311     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4312 
4313     if (!is_young) {
4314       g1h->_hot_card_cache->reset_card_counts(r);
4315     }
4316 
4317     if (!evacuation_failed) {
4318       r->rem_set()->clear_locked();
4319     }
4320   }
4321 
4322   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4323   private:
4324     size_t _cur_idx;
4325     WorkItem* _work_items;
4326   public:
4327     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4328 
4329     virtual bool do_heap_region(HeapRegion* r) {
4330       _work_items[_cur_idx++] = WorkItem(r);
4331       return false;
4332     }
4333   };
4334 
4335   void prepare_work() {
4336     G1PrepareFreeCollectionSetClosure cl(_work_items);
4337     _collection_set->iterate(&cl);
4338   }
4339 
4340   void complete_work() {
4341     _cl.complete_work();
4342 
4343     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4344     policy->record_max_rs_lengths(_rs_lengths);
4345     policy->cset_regions_freed();
4346   }
4347 public:
4348   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4349     AbstractGangTask("G1 Free Collection Set"),
4350     _cl(evacuation_info, surviving_young_words),
4351     _collection_set(collection_set),
4352     _surviving_young_words(surviving_young_words),
4353     _serial_work_claim(0),
4354     _rs_lengths(0),
4355     _parallel_work_claim(0),
4356     _num_work_items(collection_set->region_length()),
4357     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4358     prepare_work();
4359   }
4360 
4361   ~G1FreeCollectionSetTask() {
4362     complete_work();
4363     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4364   }
4365 
4366   // Chunk size for work distribution. The chosen value has been determined experimentally
4367   // to be a good tradeoff between overhead and achievable parallelism.
4368   static uint chunk_size() { return 32; }
4369 
4370   virtual void work(uint worker_id) {
4371     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4372 
4373     // Claim serial work.
4374     if (_serial_work_claim == 0) {
4375       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4376       if (value == 0) {
4377         double serial_time = os::elapsedTime();
4378         do_serial_work();
4379         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4380       }
4381     }
4382 
4383     // Start parallel work.
4384     double young_time = 0.0;
4385     bool has_young_time = false;
4386     double non_young_time = 0.0;
4387     bool has_non_young_time = false;
4388 
4389     while (true) {
4390       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4391       size_t cur = end - chunk_size();
4392 
4393       if (cur >= _num_work_items) {
4394         break;
4395       }
4396 
4397       double start_time = os::elapsedTime();
4398 
4399       end = MIN2(end, _num_work_items);
4400 
4401       for (; cur < end; cur++) {
4402         bool is_young = _work_items[cur].is_young;
4403 
4404         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4405 
4406         double end_time = os::elapsedTime();
4407         double time_taken = end_time - start_time;
4408         if (is_young) {
4409           young_time += time_taken;
4410           has_young_time = true;
4411         } else {
4412           non_young_time += time_taken;
4413           has_non_young_time = true;
4414         }
4415         start_time = end_time;
4416       }
4417     }
4418 
4419     if (has_young_time) {
4420       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4421     }
4422     if (has_non_young_time) {
4423       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4424     }
4425   }
4426 };
4427 
4428 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4429   _eden.clear();
4430 
4431   double free_cset_start_time = os::elapsedTime();
4432 
4433   {
4434     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4435     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4436 
4437     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4438 
4439     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4440                         cl.name(),
4441                         num_workers,
4442                         _collection_set.region_length());
4443     workers()->run_task(&cl, num_workers);
4444   }
4445   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4446 
4447   collection_set->clear();
4448 }
4449 
4450 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4451  private:
4452   FreeRegionList* _free_region_list;
4453   HeapRegionSet* _proxy_set;
4454   uint _humongous_objects_reclaimed;
4455   uint _humongous_regions_reclaimed;
4456   size_t _freed_bytes;
4457  public:
4458 
4459   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4460     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4461   }
4462 
4463   virtual bool do_heap_region(HeapRegion* r) {
4464     if (!r->is_starts_humongous()) {
4465       return false;
4466     }
4467 
4468     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4469 
4470     oop obj = (oop)r->bottom();
4471     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4472 
4473     // The following checks whether the humongous object is live are sufficient.
4474     // The main additional check (in addition to having a reference from the roots
4475     // or the young gen) is whether the humongous object has a remembered set entry.
4476     //
4477     // A humongous object cannot be live if there is no remembered set for it
4478     // because:
4479     // - there can be no references from within humongous starts regions referencing
4480     // the object because we never allocate other objects into them.
4481     // (I.e. there are no intra-region references that may be missed by the
4482     // remembered set)
4483     // - as soon there is a remembered set entry to the humongous starts region
4484     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4485     // until the end of a concurrent mark.
4486     //
4487     // It is not required to check whether the object has been found dead by marking
4488     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4489     // all objects allocated during that time are considered live.
4490     // SATB marking is even more conservative than the remembered set.
4491     // So if at this point in the collection there is no remembered set entry,
4492     // nobody has a reference to it.
4493     // At the start of collection we flush all refinement logs, and remembered sets
4494     // are completely up-to-date wrt to references to the humongous object.
4495     //
4496     // Other implementation considerations:
4497     // - never consider object arrays at this time because they would pose
4498     // considerable effort for cleaning up the the remembered sets. This is
4499     // required because stale remembered sets might reference locations that
4500     // are currently allocated into.
4501     uint region_idx = r->hrm_index();
4502     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4503         !r->rem_set()->is_empty()) {
4504       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",
4505                                region_idx,
4506                                (size_t)obj->size() * HeapWordSize,
4507                                p2i(r->bottom()),
4508                                r->rem_set()->occupied(),
4509                                r->rem_set()->strong_code_roots_list_length(),
4510                                next_bitmap->is_marked(r->bottom()),
4511                                g1h->is_humongous_reclaim_candidate(region_idx),
4512                                obj->is_typeArray()
4513                               );
4514       return false;
4515     }
4516 
4517     guarantee(obj->is_typeArray(),
4518               "Only eagerly reclaiming type arrays is supported, but the object "
4519               PTR_FORMAT " is not.", p2i(r->bottom()));
4520 
4521     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",
4522                              region_idx,
4523                              (size_t)obj->size() * HeapWordSize,
4524                              p2i(r->bottom()),
4525                              r->rem_set()->occupied(),
4526                              r->rem_set()->strong_code_roots_list_length(),
4527                              next_bitmap->is_marked(r->bottom()),
4528                              g1h->is_humongous_reclaim_candidate(region_idx),
4529                              obj->is_typeArray()
4530                             );
4531 
4532     G1ConcurrentMark* const cm = g1h->concurrent_mark();
4533     cm->humongous_object_eagerly_reclaimed(r);
4534     assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4535            "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4536            region_idx,
4537            BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4538            BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4539     _humongous_objects_reclaimed++;
4540     do {
4541       HeapRegion* next = g1h->next_region_in_humongous(r);
4542       _freed_bytes += r->used();
4543       r->set_containing_set(NULL);
4544       _humongous_regions_reclaimed++;
4545       g1h->free_humongous_region(r, _free_region_list);
4546       r = next;
4547     } while (r != NULL);
4548 
4549     return false;
4550   }
4551 
4552   uint humongous_objects_reclaimed() {
4553     return _humongous_objects_reclaimed;
4554   }
4555 
4556   uint humongous_regions_reclaimed() {
4557     return _humongous_regions_reclaimed;
4558   }
4559 
4560   size_t bytes_freed() const {
4561     return _freed_bytes;
4562   }
4563 };
4564 
4565 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4566   assert_at_safepoint_on_vm_thread();
4567 
4568   if (!G1EagerReclaimHumongousObjects ||
4569       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4570     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4571     return;
4572   }
4573 
4574   double start_time = os::elapsedTime();
4575 
4576   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4577 
4578   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4579   heap_region_iterate(&cl);
4580 
4581   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4582 
4583   G1HRPrinter* hrp = hr_printer();
4584   if (hrp->is_active()) {
4585     FreeRegionListIterator iter(&local_cleanup_list);
4586     while (iter.more_available()) {
4587       HeapRegion* hr = iter.get_next();
4588       hrp->cleanup(hr);
4589     }
4590   }
4591 
4592   prepend_to_freelist(&local_cleanup_list);
4593   decrement_summary_bytes(cl.bytes_freed());
4594 
4595   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4596                                                                     cl.humongous_objects_reclaimed());
4597 }
4598 
4599 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4600 public:
4601   virtual bool do_heap_region(HeapRegion* r) {
4602     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4603     G1CollectedHeap::heap()->clear_in_cset(r);
4604     r->set_young_index_in_cset(-1);
4605     return false;
4606   }
4607 };
4608 
4609 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4610   G1AbandonCollectionSetClosure cl;
4611   collection_set->iterate(&cl);
4612 
4613   collection_set->clear();
4614   collection_set->stop_incremental_building();
4615 }
4616 
4617 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4618   return _allocator->is_retained_old_region(hr);
4619 }
4620 
4621 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4622   _eden.add(hr);
4623   _g1_policy->set_region_eden(hr);
4624 }
4625 
4626 #ifdef ASSERT
4627 
4628 class NoYoungRegionsClosure: public HeapRegionClosure {
4629 private:
4630   bool _success;
4631 public:
4632   NoYoungRegionsClosure() : _success(true) { }
4633   bool do_heap_region(HeapRegion* r) {
4634     if (r->is_young()) {
4635       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4636                             p2i(r->bottom()), p2i(r->end()));
4637       _success = false;
4638     }
4639     return false;
4640   }
4641   bool success() { return _success; }
4642 };
4643 
4644 bool G1CollectedHeap::check_young_list_empty() {
4645   bool ret = (young_regions_count() == 0);
4646 
4647   NoYoungRegionsClosure closure;
4648   heap_region_iterate(&closure);
4649   ret = ret && closure.success();
4650 
4651   return ret;
4652 }
4653 
4654 #endif // ASSERT
4655 
4656 class TearDownRegionSetsClosure : public HeapRegionClosure {
4657 private:
4658   HeapRegionSet *_old_set;
4659 
4660 public:
4661   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4662 
4663   bool do_heap_region(HeapRegion* r) {
4664     if (r->is_old()) {
4665       _old_set->remove(r);
4666     } else if(r->is_young()) {
4667       r->uninstall_surv_rate_group();
4668     } else {
4669       // We ignore free regions, we'll empty the free list afterwards.
4670       // We ignore humongous regions, we're not tearing down the
4671       // humongous regions set.
4672       assert(r->is_free() || r->is_humongous(),
4673              "it cannot be another type");
4674     }
4675     return false;
4676   }
4677 
4678   ~TearDownRegionSetsClosure() {
4679     assert(_old_set->is_empty(), "post-condition");
4680   }
4681 };
4682 
4683 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4684   assert_at_safepoint_on_vm_thread();
4685 
4686   if (!free_list_only) {
4687     TearDownRegionSetsClosure cl(&_old_set);
4688     heap_region_iterate(&cl);
4689 
4690     // Note that emptying the _young_list is postponed and instead done as
4691     // the first step when rebuilding the regions sets again. The reason for
4692     // this is that during a full GC string deduplication needs to know if
4693     // a collected region was young or old when the full GC was initiated.
4694   }
4695   _hrm.remove_all_free_regions();
4696 }
4697 
4698 void G1CollectedHeap::increase_used(size_t bytes) {
4699   _summary_bytes_used += bytes;
4700 }
4701 
4702 void G1CollectedHeap::decrease_used(size_t bytes) {
4703   assert(_summary_bytes_used >= bytes,
4704          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4705          _summary_bytes_used, bytes);
4706   _summary_bytes_used -= bytes;
4707 }
4708 
4709 void G1CollectedHeap::set_used(size_t bytes) {
4710   _summary_bytes_used = bytes;
4711 }
4712 
4713 class RebuildRegionSetsClosure : public HeapRegionClosure {
4714 private:
4715   bool            _free_list_only;
4716   HeapRegionSet*   _old_set;
4717   HeapRegionManager*   _hrm;
4718   size_t          _total_used;
4719 
4720 public:
4721   RebuildRegionSetsClosure(bool free_list_only,
4722                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
4723     _free_list_only(free_list_only),
4724     _old_set(old_set), _hrm(hrm), _total_used(0) {
4725     assert(_hrm->num_free_regions() == 0, "pre-condition");
4726     if (!free_list_only) {
4727       assert(_old_set->is_empty(), "pre-condition");
4728     }
4729   }
4730 
4731   bool do_heap_region(HeapRegion* r) {
4732     // After full GC, no region should have a remembered set.
4733     r->rem_set()->clear(true);
4734     if (r->is_empty()) {
4735       // Add free regions to the free list
4736       r->set_free();
4737       _hrm->insert_into_free_list(r);
4738     } else if (!_free_list_only) {
4739 
4740       if (r->is_humongous()) {
4741         // We ignore humongous regions. We left the humongous set unchanged.
4742       } else {
4743         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4744         // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
4745         r->move_to_old();
4746         _old_set->add(r);
4747       }
4748       _total_used += r->used();
4749     }
4750 
4751     return false;
4752   }
4753 
4754   size_t total_used() {
4755     return _total_used;
4756   }
4757 };
4758 
4759 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4760   assert_at_safepoint_on_vm_thread();
4761 
4762   if (!free_list_only) {
4763     _eden.clear();
4764     _survivor.clear();
4765   }
4766 
4767   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4768   heap_region_iterate(&cl);
4769 
4770   if (!free_list_only) {
4771     set_used(cl.total_used());
4772     if (_archive_allocator != NULL) {
4773       _archive_allocator->clear_used();
4774     }
4775   }
4776   assert(used_unlocked() == recalculate_used(),
4777          "inconsistent used_unlocked(), "
4778          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4779          used_unlocked(), recalculate_used());
4780 }
4781 
4782 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4783   HeapRegion* hr = heap_region_containing(p);
4784   return hr->is_in(p);
4785 }
4786 
4787 // Methods for the mutator alloc region
4788 
4789 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4790                                                       bool force) {
4791   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4792   bool should_allocate = g1_policy()->should_allocate_mutator_region();
4793   if (force || should_allocate) {
4794     HeapRegion* new_alloc_region = new_region(word_size,
4795                                               false /* is_old */,
4796                                               false /* do_expand */);
4797     if (new_alloc_region != NULL) {
4798       set_region_short_lived_locked(new_alloc_region);
4799       _hr_printer.alloc(new_alloc_region, !should_allocate);
4800       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4801       _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4802       return new_alloc_region;
4803     }
4804   }
4805   return NULL;
4806 }
4807 
4808 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4809                                                   size_t allocated_bytes) {
4810   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4811   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4812 
4813   collection_set()->add_eden_region(alloc_region);
4814   increase_used(allocated_bytes);
4815   _hr_printer.retire(alloc_region);
4816   // We update the eden sizes here, when the region is retired,
4817   // instead of when it's allocated, since this is the point that its
4818   // used space has been recored in _summary_bytes_used.
4819   g1mm()->update_eden_size();
4820 }
4821 
4822 // Methods for the GC alloc regions
4823 
4824 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4825   if (dest.is_old()) {
4826     return true;
4827   } else {
4828     return survivor_regions_count() < g1_policy()->max_survivor_regions();
4829   }
4830 }
4831 
4832 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4833   assert(FreeList_lock->owned_by_self(), "pre-condition");
4834 
4835   if (!has_more_regions(dest)) {
4836     return NULL;
4837   }
4838 
4839   const bool is_survivor = dest.is_young();
4840 
4841   HeapRegion* new_alloc_region = new_region(word_size,
4842                                             !is_survivor,
4843                                             true /* do_expand */);
4844   if (new_alloc_region != NULL) {
4845     if (is_survivor) {
4846       new_alloc_region->set_survivor();
4847       _survivor.add(new_alloc_region);
4848       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4849     } else {
4850       new_alloc_region->set_old();
4851       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4852     }
4853     _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4854     _hr_printer.alloc(new_alloc_region);
4855     bool during_im = collector_state()->in_initial_mark_gc();
4856     new_alloc_region->note_start_of_copying(during_im);
4857     return new_alloc_region;
4858   }
4859   return NULL;
4860 }
4861 
4862 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4863                                              size_t allocated_bytes,
4864                                              InCSetState dest) {
4865   bool during_im = collector_state()->in_initial_mark_gc();
4866   alloc_region->note_end_of_copying(during_im);
4867   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4868   if (dest.is_old()) {
4869     _old_set.add(alloc_region);
4870   }
4871   _hr_printer.retire(alloc_region);
4872 }
4873 
4874 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4875   bool expanded = false;
4876   uint index = _hrm.find_highest_free(&expanded);
4877 
4878   if (index != G1_NO_HRM_INDEX) {
4879     if (expanded) {
4880       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4881                                 HeapRegion::GrainWords * HeapWordSize);
4882     }
4883     _hrm.allocate_free_regions_starting_at(index, 1);
4884     return region_at(index);
4885   }
4886   return NULL;
4887 }
4888 
4889 // Optimized nmethod scanning
4890 
4891 class RegisterNMethodOopClosure: public OopClosure {
4892   G1CollectedHeap* _g1h;
4893   nmethod* _nm;
4894 
4895   template <class T> void do_oop_work(T* p) {
4896     T heap_oop = RawAccess<>::oop_load(p);
4897     if (!CompressedOops::is_null(heap_oop)) {
4898       oop obj = CompressedOops::decode_not_null(heap_oop);
4899       HeapRegion* hr = _g1h->heap_region_containing(obj);
4900       assert(!hr->is_continues_humongous(),
4901              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4902              " starting at " HR_FORMAT,
4903              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4904 
4905       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4906       hr->add_strong_code_root_locked(_nm);
4907     }
4908   }
4909 
4910 public:
4911   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4912     _g1h(g1h), _nm(nm) {}
4913 
4914   void do_oop(oop* p)       { do_oop_work(p); }
4915   void do_oop(narrowOop* p) { do_oop_work(p); }
4916 };
4917 
4918 class UnregisterNMethodOopClosure: public OopClosure {
4919   G1CollectedHeap* _g1h;
4920   nmethod* _nm;
4921 
4922   template <class T> void do_oop_work(T* p) {
4923     T heap_oop = RawAccess<>::oop_load(p);
4924     if (!CompressedOops::is_null(heap_oop)) {
4925       oop obj = CompressedOops::decode_not_null(heap_oop);
4926       HeapRegion* hr = _g1h->heap_region_containing(obj);
4927       assert(!hr->is_continues_humongous(),
4928              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4929              " starting at " HR_FORMAT,
4930              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4931 
4932       hr->remove_strong_code_root(_nm);
4933     }
4934   }
4935 
4936 public:
4937   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4938     _g1h(g1h), _nm(nm) {}
4939 
4940   void do_oop(oop* p)       { do_oop_work(p); }
4941   void do_oop(narrowOop* p) { do_oop_work(p); }
4942 };
4943 
4944 // Returns true if the reference points to an object that
4945 // can move in an incremental collection.
4946 bool G1CollectedHeap::is_scavengable(oop obj) {
4947   HeapRegion* hr = heap_region_containing(obj);
4948   return !hr->is_pinned();
4949 }
4950 
4951 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4952   guarantee(nm != NULL, "sanity");
4953   RegisterNMethodOopClosure reg_cl(this, nm);
4954   nm->oops_do(&reg_cl);
4955 }
4956 
4957 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4958   guarantee(nm != NULL, "sanity");
4959   UnregisterNMethodOopClosure reg_cl(this, nm);
4960   nm->oops_do(&reg_cl, true);
4961 }
4962 
4963 void G1CollectedHeap::purge_code_root_memory() {
4964   double purge_start = os::elapsedTime();
4965   G1CodeRootSet::purge();
4966   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4967   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4968 }
4969 
4970 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4971   G1CollectedHeap* _g1h;
4972 
4973 public:
4974   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4975     _g1h(g1h) {}
4976 
4977   void do_code_blob(CodeBlob* cb) {
4978     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4979     if (nm == NULL) {
4980       return;
4981     }
4982 
4983     if (ScavengeRootsInCode) {
4984       _g1h->register_nmethod(nm);
4985     }
4986   }
4987 };
4988 
4989 void G1CollectedHeap::rebuild_strong_code_roots() {
4990   RebuildStrongCodeRootClosure blob_cl(this);
4991   CodeCache::blobs_do(&blob_cl);
4992 }
4993 
4994 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4995   GrowableArray<GCMemoryManager*> memory_managers(2);
4996   memory_managers.append(&_memory_manager);
4997   memory_managers.append(&_full_gc_memory_manager);
4998   return memory_managers;
4999 }
5000 
5001 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5002   GrowableArray<MemoryPool*> memory_pools(3);
5003   memory_pools.append(_eden_pool);
5004   memory_pools.append(_survivor_pool);
5005   memory_pools.append(_old_pool);
5006   return memory_pools;
5007 }