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/bufferingOopClosure.hpp"
  32 #include "gc/g1/concurrentMarkThread.inline.hpp"
  33 #include "gc/g1/g1Allocator.inline.hpp"
  34 #include "gc/g1/g1CollectedHeap.inline.hpp"
  35 #include "gc/g1/g1CollectionSet.hpp"
  36 #include "gc/g1/g1CollectorPolicy.hpp"
  37 #include "gc/g1/g1CollectorState.hpp"
  38 #include "gc/g1/g1ConcurrentRefine.hpp"
  39 #include "gc/g1/g1ConcurrentRefineThread.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/g1YCTypes.hpp"
  57 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
  58 #include "gc/g1/heapRegion.inline.hpp"
  59 #include "gc/g1/heapRegionRemSet.hpp"
  60 #include "gc/g1/heapRegionSet.inline.hpp"
  61 #include "gc/g1/vm_operations_g1.hpp"
  62 #include "gc/shared/gcHeapSummary.hpp"
  63 #include "gc/shared/gcId.hpp"
  64 #include "gc/shared/gcLocker.inline.hpp"
  65 #include "gc/shared/gcTimer.hpp"
  66 #include "gc/shared/gcTrace.hpp"
  67 #include "gc/shared/gcTraceTime.inline.hpp"
  68 #include "gc/shared/generationSpec.hpp"
  69 #include "gc/shared/isGCActiveMark.hpp"
  70 #include "gc/shared/preservedMarks.inline.hpp"
  71 #include "gc/shared/suspendibleThreadSet.hpp"
  72 #include "gc/shared/referenceProcessor.inline.hpp"
  73 #include "gc/shared/taskqueue.inline.hpp"
  74 #include "gc/shared/weakProcessor.hpp"
  75 #include "logging/log.hpp"
  76 #include "memory/allocation.hpp"
  77 #include "memory/iterator.hpp"
  78 #include "memory/resourceArea.hpp"
  79 #include "oops/oop.inline.hpp"
  80 #include "prims/resolvedMethodTable.hpp"
  81 #include "runtime/atomic.hpp"
  82 #include "runtime/init.hpp"
  83 #include "runtime/orderAccess.inline.hpp"
  84 #include "runtime/threadSMR.hpp"
  85 #include "runtime/vmThread.hpp"
  86 #include "utilities/align.hpp"
  87 #include "utilities/globalDefinitions.hpp"
  88 #include "utilities/stack.inline.hpp"
  89 
  90 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  91 
  92 // INVARIANTS/NOTES
  93 //
  94 // All allocation activity covered by the G1CollectedHeap interface is
  95 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  96 // and allocate_new_tlab, which are the "entry" points to the
  97 // allocation code from the rest of the JVM.  (Note that this does not
  98 // apply to TLAB allocation, which is not part of this interface: it
  99 // is done by clients of this interface.)
 100 
 101 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 102  private:
 103   size_t _num_dirtied;
 104   G1CollectedHeap* _g1h;
 105   G1SATBCardTableLoggingModRefBS* _g1_bs;
 106 
 107   HeapRegion* region_for_card(jbyte* card_ptr) const {
 108     return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
 109   }
 110 
 111   bool will_become_free(HeapRegion* hr) const {
 112     // A region will be freed by free_collection_set if the region is in the
 113     // collection set and has not had an evacuation failure.
 114     return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
 115   }
 116 
 117  public:
 118   RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
 119     _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
 120 
 121   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 122     HeapRegion* hr = region_for_card(card_ptr);
 123 
 124     // Should only dirty cards in regions that won't be freed.
 125     if (!will_become_free(hr)) {
 126       *card_ptr = CardTableModRefBS::dirty_card_val();
 127       _num_dirtied++;
 128     }
 129 
 130     return true;
 131   }
 132 
 133   size_t num_dirtied()   const { return _num_dirtied; }
 134 };
 135 
 136 
 137 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 138   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 139 }
 140 
 141 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 142   // The from card cache is not the memory that is actually committed. So we cannot
 143   // take advantage of the zero_filled parameter.
 144   reset_from_card_cache(start_idx, num_regions);
 145 }
 146 
 147 
 148 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
 149                                              MemRegion mr) {
 150   return new HeapRegion(hrs_index, bot(), mr);
 151 }
 152 
 153 // Private methods.
 154 
 155 HeapRegion*
 156 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 157   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 158   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 159     if (!_secondary_free_list.is_empty()) {
 160       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 161                                       "secondary_free_list has %u entries",
 162                                       _secondary_free_list.length());
 163       // It looks as if there are free regions available on the
 164       // secondary_free_list. Let's move them to the free_list and try
 165       // again to allocate from it.
 166       append_secondary_free_list();
 167 
 168       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 169              "empty we should have moved at least one entry to the free_list");
 170       HeapRegion* res = _hrm.allocate_free_region(is_old);
 171       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 172                                       "allocated " HR_FORMAT " from secondary_free_list",
 173                                       HR_FORMAT_PARAMS(res));
 174       return res;
 175     }
 176 
 177     // Wait here until we get notified either when (a) there are no
 178     // more free regions coming or (b) some regions have been moved on
 179     // the secondary_free_list.
 180     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 181   }
 182 
 183   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 184                                   "could not allocate from secondary_free_list");
 185   return NULL;
 186 }
 187 
 188 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 189   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 190          "the only time we use this to allocate a humongous region is "
 191          "when we are allocating a single humongous region");
 192 
 193   HeapRegion* res;
 194   if (G1StressConcRegionFreeing) {
 195     if (!_secondary_free_list.is_empty()) {
 196       log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 197                                       "forced to look at the secondary_free_list");
 198       res = new_region_try_secondary_free_list(is_old);
 199       if (res != NULL) {
 200         return res;
 201       }
 202     }
 203   }
 204 
 205   res = _hrm.allocate_free_region(is_old);
 206 
 207   if (res == NULL) {
 208     log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
 209                                     "res == NULL, trying the secondary_free_list");
 210     res = new_region_try_secondary_free_list(is_old);
 211   }
 212   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 213     // Currently, only attempts to allocate GC alloc regions set
 214     // do_expand to true. So, we should only reach here during a
 215     // safepoint. If this assumption changes we might have to
 216     // reconsider the use of _expand_heap_after_alloc_failure.
 217     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 218 
 219     log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
 220                               word_size * HeapWordSize);
 221 
 222     if (expand(word_size * HeapWordSize)) {
 223       // Given that expand() succeeded in expanding the heap, and we
 224       // always expand the heap by an amount aligned to the heap
 225       // region size, the free list should in theory not be empty.
 226       // In either case allocate_free_region() will check for NULL.
 227       res = _hrm.allocate_free_region(is_old);
 228     } else {
 229       _expand_heap_after_alloc_failure = false;
 230     }
 231   }
 232   return res;
 233 }
 234 
 235 HeapWord*
 236 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 237                                                            uint num_regions,
 238                                                            size_t word_size,
 239                                                            AllocationContext_t context) {
 240   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 241   assert(is_humongous(word_size), "word_size should be humongous");
 242   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 243 
 244   // Index of last region in the series.
 245   uint last = first + num_regions - 1;
 246 
 247   // We need to initialize the region(s) we just discovered. This is
 248   // a bit tricky given that it can happen concurrently with
 249   // refinement threads refining cards on these regions and
 250   // potentially wanting to refine the BOT as they are scanning
 251   // those cards (this can happen shortly after a cleanup; see CR
 252   // 6991377). So we have to set up the region(s) carefully and in
 253   // a specific order.
 254 
 255   // The word size sum of all the regions we will allocate.
 256   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 257   assert(word_size <= word_size_sum, "sanity");
 258 
 259   // This will be the "starts humongous" region.
 260   HeapRegion* first_hr = region_at(first);
 261   // The header of the new object will be placed at the bottom of
 262   // the first region.
 263   HeapWord* new_obj = first_hr->bottom();
 264   // This will be the new top of the new object.
 265   HeapWord* obj_top = new_obj + word_size;
 266 
 267   // First, we need to zero the header of the space that we will be
 268   // allocating. When we update top further down, some refinement
 269   // threads might try to scan the region. By zeroing the header we
 270   // ensure that any thread that will try to scan the region will
 271   // come across the zero klass word and bail out.
 272   //
 273   // NOTE: It would not have been correct to have used
 274   // CollectedHeap::fill_with_object() and make the space look like
 275   // an int array. The thread that is doing the allocation will
 276   // later update the object header to a potentially different array
 277   // type and, for a very short period of time, the klass and length
 278   // fields will be inconsistent. This could cause a refinement
 279   // thread to calculate the object size incorrectly.
 280   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 281 
 282   // Next, pad out the unused tail of the last region with filler
 283   // objects, for improved usage accounting.
 284   // How many words we use for filler objects.
 285   size_t word_fill_size = word_size_sum - word_size;
 286 
 287   // How many words memory we "waste" which cannot hold a filler object.
 288   size_t words_not_fillable = 0;
 289 
 290   if (word_fill_size >= min_fill_size()) {
 291     fill_with_objects(obj_top, word_fill_size);
 292   } else if (word_fill_size > 0) {
 293     // We have space to fill, but we cannot fit an object there.
 294     words_not_fillable = word_fill_size;
 295     word_fill_size = 0;
 296   }
 297 
 298   // We will set up the first region as "starts humongous". This
 299   // will also update the BOT covering all the regions to reflect
 300   // that there is a single object that starts at the bottom of the
 301   // first region.
 302   first_hr->set_starts_humongous(obj_top, word_fill_size);
 303   first_hr->set_allocation_context(context);
 304   // Then, if there are any, we will set up the "continues
 305   // humongous" regions.
 306   HeapRegion* hr = NULL;
 307   for (uint i = first + 1; i <= last; ++i) {
 308     hr = region_at(i);
 309     hr->set_continues_humongous(first_hr);
 310     hr->set_allocation_context(context);
 311   }
 312 
 313   // Up to this point no concurrent thread would have been able to
 314   // do any scanning on any region in this series. All the top
 315   // fields still point to bottom, so the intersection between
 316   // [bottom,top] and [card_start,card_end] will be empty. Before we
 317   // update the top fields, we'll do a storestore to make sure that
 318   // no thread sees the update to top before the zeroing of the
 319   // object header and the BOT initialization.
 320   OrderAccess::storestore();
 321 
 322   // Now, we will update the top fields of the "continues humongous"
 323   // regions except the last one.
 324   for (uint i = first; i < last; ++i) {
 325     hr = region_at(i);
 326     hr->set_top(hr->end());
 327   }
 328 
 329   hr = region_at(last);
 330   // If we cannot fit a filler object, we must set top to the end
 331   // of the humongous object, otherwise we cannot iterate the heap
 332   // and the BOT will not be complete.
 333   hr->set_top(hr->end() - words_not_fillable);
 334 
 335   assert(hr->bottom() < obj_top && obj_top <= hr->end(),
 336          "obj_top should be in last region");
 337 
 338   _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
 339 
 340   assert(words_not_fillable == 0 ||
 341          first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
 342          "Miscalculation in humongous allocation");
 343 
 344   increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
 345 
 346   for (uint i = first; i <= last; ++i) {
 347     hr = region_at(i);
 348     _humongous_set.add(hr);
 349     _hr_printer.alloc(hr);
 350   }
 351 
 352   return new_obj;
 353 }
 354 
 355 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 356   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
 357   return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 358 }
 359 
 360 // If could fit into free regions w/o expansion, try.
 361 // Otherwise, if can expand, do so.
 362 // Otherwise, if using ex regions might help, try with ex given back.
 363 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 364   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 365 
 366   _verifier->verify_region_sets_optional();
 367 
 368   uint first = G1_NO_HRM_INDEX;
 369   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 370 
 371   if (obj_regions == 1) {
 372     // Only one region to allocate, try to use a fast path by directly allocating
 373     // from the free lists. Do not try to expand here, we will potentially do that
 374     // later.
 375     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 376     if (hr != NULL) {
 377       first = hr->hrm_index();
 378     }
 379   } else {
 380     // We can't allocate humongous regions spanning more than one region while
 381     // cleanupComplete() is running, since some of the regions we find to be
 382     // empty might not yet be added to the free list. It is not straightforward
 383     // to know in which list they are on so that we can remove them. We only
 384     // need to do this if we need to allocate more than one region to satisfy the
 385     // current humongous allocation request. If we are only allocating one region
 386     // we use the one-region region allocation code (see above), that already
 387     // potentially waits for regions from the secondary free list.
 388     wait_while_free_regions_coming();
 389     append_secondary_free_list_if_not_empty_with_lock();
 390 
 391     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 392     // are lucky enough to find some.
 393     first = _hrm.find_contiguous_only_empty(obj_regions);
 394     if (first != G1_NO_HRM_INDEX) {
 395       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 396     }
 397   }
 398 
 399   if (first == G1_NO_HRM_INDEX) {
 400     // Policy: We could not find enough regions for the humongous object in the
 401     // free list. Look through the heap to find a mix of free and uncommitted regions.
 402     // If so, try expansion.
 403     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 404     if (first != G1_NO_HRM_INDEX) {
 405       // We found something. Make sure these regions are committed, i.e. expand
 406       // the heap. Alternatively we could do a defragmentation GC.
 407       log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
 408                                     word_size * HeapWordSize);
 409 
 410       _hrm.expand_at(first, obj_regions, workers());
 411       g1_policy()->record_new_heap_size(num_regions());
 412 
 413 #ifdef ASSERT
 414       for (uint i = first; i < first + obj_regions; ++i) {
 415         HeapRegion* hr = region_at(i);
 416         assert(hr->is_free(), "sanity");
 417         assert(hr->is_empty(), "sanity");
 418         assert(is_on_master_free_list(hr), "sanity");
 419       }
 420 #endif
 421       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 422     } else {
 423       // Policy: Potentially trigger a defragmentation GC.
 424     }
 425   }
 426 
 427   HeapWord* result = NULL;
 428   if (first != G1_NO_HRM_INDEX) {
 429     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 430                                                        word_size, context);
 431     assert(result != NULL, "it should always return a valid result");
 432 
 433     // A successful humongous object allocation changes the used space
 434     // information of the old generation so we need to recalculate the
 435     // sizes and update the jstat counters here.
 436     g1mm()->update_sizes();
 437   }
 438 
 439   _verifier->verify_region_sets_optional();
 440 
 441   return result;
 442 }
 443 
 444 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 445   assert_heap_not_locked_and_not_at_safepoint();
 446   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 447 
 448   return attempt_allocation(word_size);
 449 }
 450 
 451 HeapWord*
 452 G1CollectedHeap::mem_allocate(size_t word_size,
 453                               bool*  gc_overhead_limit_was_exceeded) {
 454   assert_heap_not_locked_and_not_at_safepoint();
 455 
 456   if (is_humongous(word_size)) {
 457     return attempt_allocation_humongous(word_size);
 458   }
 459   return attempt_allocation(word_size);
 460 }
 461 
 462 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 463                                                    AllocationContext_t context) {
 464   ResourceMark rm; // For retrieving the thread names in log messages.
 465 
 466   // Make sure you read the note in attempt_allocation_humongous().
 467 
 468   assert_heap_not_locked_and_not_at_safepoint();
 469   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 470          "be called for humongous allocation requests");
 471 
 472   // We should only get here after the first-level allocation attempt
 473   // (attempt_allocation()) failed to allocate.
 474 
 475   // We will loop until a) we manage to successfully perform the
 476   // allocation or b) we successfully schedule a collection which
 477   // fails to perform the allocation. b) is the only case when we'll
 478   // return NULL.
 479   HeapWord* result = NULL;
 480   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 481     bool should_try_gc;
 482     uint gc_count_before;
 483 
 484     {
 485       MutexLockerEx x(Heap_lock);
 486       result = _allocator->attempt_allocation_locked(word_size, context);
 487       if (result != NULL) {
 488         return result;
 489       }
 490 
 491       // If the GCLocker is active and we are bound for a GC, try expanding young gen.
 492       // This is different to when only GCLocker::needs_gc() is set: try to avoid
 493       // waiting because the GCLocker is active to not wait too long.
 494       if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
 495         // No need for an ergo message here, can_expand_young_list() does this when
 496         // it returns true.
 497         result = _allocator->attempt_allocation_force(word_size, context);
 498         if (result != NULL) {
 499           return result;
 500         }
 501       }
 502       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 503       // the GCLocker initiated GC has been performed and then retry. This includes
 504       // the case when the GC Locker is not active but has not been performed.
 505       should_try_gc = !GCLocker::needs_gc();
 506       // Read the GC count while still holding the Heap_lock.
 507       gc_count_before = total_collections();
 508     }
 509 
 510     if (should_try_gc) {
 511       bool succeeded;
 512       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 513                                    GCCause::_g1_inc_collection_pause);
 514       if (result != NULL) {
 515         assert(succeeded, "only way to get back a non-NULL result");
 516         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 517                              Thread::current()->name(), p2i(result));
 518         return result;
 519       }
 520 
 521       if (succeeded) {
 522         // We successfully scheduled a collection which failed to allocate. No
 523         // point in trying to allocate further. We'll just return NULL.
 524         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 525                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 526         return NULL;
 527       }
 528       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
 529                            Thread::current()->name(), word_size);
 530     } else {
 531       // Failed to schedule a collection.
 532       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 533         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 534                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 535         return NULL;
 536       }
 537       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 538       // The GCLocker is either active or the GCLocker initiated
 539       // GC has not yet been performed. Stall until it is and
 540       // then retry the allocation.
 541       GCLocker::stall_until_clear();
 542       gclocker_retry_count += 1;
 543     }
 544 
 545     // We can reach here if we were unsuccessful in scheduling a
 546     // collection (because another thread beat us to it) or if we were
 547     // stalled due to the GC locker. In either can we should retry the
 548     // allocation attempt in case another thread successfully
 549     // performed a collection and reclaimed enough space. We do the
 550     // first attempt (without holding the Heap_lock) here and the
 551     // follow-on attempt will be at the start of the next loop
 552     // iteration (after taking the Heap_lock).
 553 
 554     result = _allocator->attempt_allocation(word_size, context);
 555     if (result != NULL) {
 556       return result;
 557     }
 558 
 559     // Give a warning if we seem to be looping forever.
 560     if ((QueuedAllocationWarningCount > 0) &&
 561         (try_count % QueuedAllocationWarningCount == 0)) {
 562       log_warning(gc, alloc)("%s:  Retried allocation %u times for " SIZE_FORMAT " words",
 563                              Thread::current()->name(), try_count, word_size);
 564     }
 565   }
 566 
 567   ShouldNotReachHere();
 568   return NULL;
 569 }
 570 
 571 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 572   assert_at_safepoint(true /* should_be_vm_thread */);
 573   if (_archive_allocator == NULL) {
 574     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 575   }
 576 }
 577 
 578 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 579   // Allocations in archive regions cannot be of a size that would be considered
 580   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 581   // may be different at archive-restore time.
 582   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 583 }
 584 
 585 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 586   assert_at_safepoint(true /* should_be_vm_thread */);
 587   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 588   if (is_archive_alloc_too_large(word_size)) {
 589     return NULL;
 590   }
 591   return _archive_allocator->archive_mem_allocate(word_size);
 592 }
 593 
 594 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 595                                               size_t end_alignment_in_bytes) {
 596   assert_at_safepoint(true /* should_be_vm_thread */);
 597   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 598 
 599   // Call complete_archive to do the real work, filling in the MemRegion
 600   // array with the archive regions.
 601   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 602   delete _archive_allocator;
 603   _archive_allocator = NULL;
 604 }
 605 
 606 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 607   assert(ranges != NULL, "MemRegion array NULL");
 608   assert(count != 0, "No MemRegions provided");
 609   MemRegion reserved = _hrm.reserved();
 610   for (size_t i = 0; i < count; i++) {
 611     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 612       return false;
 613     }
 614   }
 615   return true;
 616 }
 617 
 618 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 619                                             size_t count,
 620                                             bool open) {
 621   assert(!is_init_completed(), "Expect to be called at JVM init time");
 622   assert(ranges != NULL, "MemRegion array NULL");
 623   assert(count != 0, "No MemRegions provided");
 624   MutexLockerEx x(Heap_lock);
 625 
 626   MemRegion reserved = _hrm.reserved();
 627   HeapWord* prev_last_addr = NULL;
 628   HeapRegion* prev_last_region = NULL;
 629 
 630   // Temporarily disable pretouching of heap pages. This interface is used
 631   // when mmap'ing archived heap data in, so pre-touching is wasted.
 632   FlagSetting fs(AlwaysPreTouch, false);
 633 
 634   // Enable archive object checking used by G1MarkSweep. We have to let it know
 635   // about each archive range, so that objects in those ranges aren't marked.
 636   G1ArchiveAllocator::enable_archive_object_check();
 637 
 638   // For each specified MemRegion range, allocate the corresponding G1
 639   // regions and mark them as archive regions. We expect the ranges
 640   // in ascending starting address order, without overlap.
 641   for (size_t i = 0; i < count; i++) {
 642     MemRegion curr_range = ranges[i];
 643     HeapWord* start_address = curr_range.start();
 644     size_t word_size = curr_range.word_size();
 645     HeapWord* last_address = curr_range.last();
 646     size_t commits = 0;
 647 
 648     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 649               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 650               p2i(start_address), p2i(last_address));
 651     guarantee(start_address > prev_last_addr,
 652               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 653               p2i(start_address), p2i(prev_last_addr));
 654     prev_last_addr = last_address;
 655 
 656     // Check for ranges that start in the same G1 region in which the previous
 657     // range ended, and adjust the start address so we don't try to allocate
 658     // the same region again. If the current range is entirely within that
 659     // region, skip it, just adjusting the recorded top.
 660     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 661     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 662       start_address = start_region->end();
 663       if (start_address > last_address) {
 664         increase_used(word_size * HeapWordSize);
 665         start_region->set_top(last_address + 1);
 666         continue;
 667       }
 668       start_region->set_top(start_address);
 669       curr_range = MemRegion(start_address, last_address + 1);
 670       start_region = _hrm.addr_to_region(start_address);
 671     }
 672 
 673     // Perform the actual region allocation, exiting if it fails.
 674     // Then note how much new space we have allocated.
 675     if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
 676       return false;
 677     }
 678     increase_used(word_size * HeapWordSize);
 679     if (commits != 0) {
 680       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 681                                 HeapRegion::GrainWords * HeapWordSize * commits);
 682 
 683     }
 684 
 685     // Mark each G1 region touched by the range as archive, add it to
 686     // the old set, and set the allocation context and top.
 687     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 688     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 689     prev_last_region = last_region;
 690 
 691     while (curr_region != NULL) {
 692       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 693              "Region already in use (index %u)", curr_region->hrm_index());
 694       curr_region->set_allocation_context(AllocationContext::system());
 695       if (open) {
 696         curr_region->set_open_archive();
 697       } else {
 698         curr_region->set_closed_archive();
 699       }
 700       _hr_printer.alloc(curr_region);
 701       _old_set.add(curr_region);
 702       HeapWord* top;
 703       HeapRegion* next_region;
 704       if (curr_region != last_region) {
 705         top = curr_region->end();
 706         next_region = _hrm.next_region_in_heap(curr_region);
 707       } else {
 708         top = last_address + 1;
 709         next_region = NULL;
 710       }
 711       curr_region->set_top(top);
 712       curr_region->set_first_dead(top);
 713       curr_region->set_end_of_live(top);
 714       curr_region = next_region;
 715     }
 716 
 717     // Notify mark-sweep of the archive
 718     G1ArchiveAllocator::set_range_archive(curr_range, open);
 719   }
 720   return true;
 721 }
 722 
 723 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 724   assert(!is_init_completed(), "Expect to be called at JVM init time");
 725   assert(ranges != NULL, "MemRegion array NULL");
 726   assert(count != 0, "No MemRegions provided");
 727   MemRegion reserved = _hrm.reserved();
 728   HeapWord *prev_last_addr = NULL;
 729   HeapRegion* prev_last_region = NULL;
 730 
 731   // For each MemRegion, create filler objects, if needed, in the G1 regions
 732   // that contain the address range. The address range actually within the
 733   // MemRegion will not be modified. That is assumed to have been initialized
 734   // elsewhere, probably via an mmap of archived heap data.
 735   MutexLockerEx x(Heap_lock);
 736   for (size_t i = 0; i < count; i++) {
 737     HeapWord* start_address = ranges[i].start();
 738     HeapWord* last_address = ranges[i].last();
 739 
 740     assert(reserved.contains(start_address) && reserved.contains(last_address),
 741            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 742            p2i(start_address), p2i(last_address));
 743     assert(start_address > prev_last_addr,
 744            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 745            p2i(start_address), p2i(prev_last_addr));
 746 
 747     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 748     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 749     HeapWord* bottom_address = start_region->bottom();
 750 
 751     // Check for a range beginning in the same region in which the
 752     // previous one ended.
 753     if (start_region == prev_last_region) {
 754       bottom_address = prev_last_addr + 1;
 755     }
 756 
 757     // Verify that the regions were all marked as archive regions by
 758     // alloc_archive_regions.
 759     HeapRegion* curr_region = start_region;
 760     while (curr_region != NULL) {
 761       guarantee(curr_region->is_archive(),
 762                 "Expected archive region at index %u", curr_region->hrm_index());
 763       if (curr_region != last_region) {
 764         curr_region = _hrm.next_region_in_heap(curr_region);
 765       } else {
 766         curr_region = NULL;
 767       }
 768     }
 769 
 770     prev_last_addr = last_address;
 771     prev_last_region = last_region;
 772 
 773     // Fill the memory below the allocated range with dummy object(s),
 774     // if the region bottom does not match the range start, or if the previous
 775     // range ended within the same G1 region, and there is a gap.
 776     if (start_address != bottom_address) {
 777       size_t fill_size = pointer_delta(start_address, bottom_address);
 778       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 779       increase_used(fill_size * HeapWordSize);
 780     }
 781   }
 782 }
 783 
 784 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) {
 785   assert_heap_not_locked_and_not_at_safepoint();
 786   assert(!is_humongous(word_size), "attempt_allocation() should not "
 787          "be called for humongous allocation requests");
 788 
 789   AllocationContext_t context = AllocationContext::current();
 790   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 791 
 792   if (result == NULL) {
 793     result = attempt_allocation_slow(word_size, context);
 794   }
 795   assert_heap_not_locked();
 796   if (result != NULL) {
 797     dirty_young_block(result, word_size);
 798   }
 799   return result;
 800 }
 801 
 802 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 803   assert(!is_init_completed(), "Expect to be called at JVM init time");
 804   assert(ranges != NULL, "MemRegion array NULL");
 805   assert(count != 0, "No MemRegions provided");
 806   MemRegion reserved = _hrm.reserved();
 807   HeapWord* prev_last_addr = NULL;
 808   HeapRegion* prev_last_region = NULL;
 809   size_t size_used = 0;
 810   size_t uncommitted_regions = 0;
 811 
 812   // For each Memregion, free the G1 regions that constitute it, and
 813   // notify mark-sweep that the range is no longer to be considered 'archive.'
 814   MutexLockerEx x(Heap_lock);
 815   for (size_t i = 0; i < count; i++) {
 816     HeapWord* start_address = ranges[i].start();
 817     HeapWord* last_address = ranges[i].last();
 818 
 819     assert(reserved.contains(start_address) && reserved.contains(last_address),
 820            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 821            p2i(start_address), p2i(last_address));
 822     assert(start_address > prev_last_addr,
 823            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 824            p2i(start_address), p2i(prev_last_addr));
 825     size_used += ranges[i].byte_size();
 826     prev_last_addr = last_address;
 827 
 828     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 829     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 830 
 831     // Check for ranges that start in the same G1 region in which the previous
 832     // range ended, and adjust the start address so we don't try to free
 833     // the same region again. If the current range is entirely within that
 834     // region, skip it.
 835     if (start_region == prev_last_region) {
 836       start_address = start_region->end();
 837       if (start_address > last_address) {
 838         continue;
 839       }
 840       start_region = _hrm.addr_to_region(start_address);
 841     }
 842     prev_last_region = last_region;
 843 
 844     // After verifying that each region was marked as an archive region by
 845     // alloc_archive_regions, set it free and empty and uncommit it.
 846     HeapRegion* curr_region = start_region;
 847     while (curr_region != NULL) {
 848       guarantee(curr_region->is_archive(),
 849                 "Expected archive region at index %u", curr_region->hrm_index());
 850       uint curr_index = curr_region->hrm_index();
 851       _old_set.remove(curr_region);
 852       curr_region->set_free();
 853       curr_region->set_top(curr_region->bottom());
 854       if (curr_region != last_region) {
 855         curr_region = _hrm.next_region_in_heap(curr_region);
 856       } else {
 857         curr_region = NULL;
 858       }
 859       _hrm.shrink_at(curr_index, 1);
 860       uncommitted_regions++;
 861     }
 862 
 863     // Notify mark-sweep that this is no longer an archive range.
 864     G1ArchiveAllocator::set_range_archive(ranges[i], false);
 865   }
 866 
 867   if (uncommitted_regions != 0) {
 868     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 869                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 870   }
 871   decrease_used(size_used);
 872 }
 873 
 874 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
 875   ResourceMark rm; // For retrieving the thread names in log messages.
 876 
 877   // The structure of this method has a lot of similarities to
 878   // attempt_allocation_slow(). The reason these two were not merged
 879   // into a single one is that such a method would require several "if
 880   // allocation is not humongous do this, otherwise do that"
 881   // conditional paths which would obscure its flow. In fact, an early
 882   // version of this code did use a unified method which was harder to
 883   // follow and, as a result, it had subtle bugs that were hard to
 884   // track down. So keeping these two methods separate allows each to
 885   // be more readable. It will be good to keep these two in sync as
 886   // much as possible.
 887 
 888   assert_heap_not_locked_and_not_at_safepoint();
 889   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 890          "should only be called for humongous allocations");
 891 
 892   // Humongous objects can exhaust the heap quickly, so we should check if we
 893   // need to start a marking cycle at each humongous object allocation. We do
 894   // the check before we do the actual allocation. The reason for doing it
 895   // before the allocation is that we avoid having to keep track of the newly
 896   // allocated memory while we do a GC.
 897   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 898                                            word_size)) {
 899     collect(GCCause::_g1_humongous_allocation);
 900   }
 901 
 902   // We will loop until a) we manage to successfully perform the
 903   // allocation or b) we successfully schedule a collection which
 904   // fails to perform the allocation. b) is the only case when we'll
 905   // return NULL.
 906   HeapWord* result = NULL;
 907   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 908     bool should_try_gc;
 909     uint gc_count_before;
 910 
 911 
 912     {
 913       MutexLockerEx x(Heap_lock);
 914 
 915       // Given that humongous objects are not allocated in young
 916       // regions, we'll first try to do the allocation without doing a
 917       // collection hoping that there's enough space in the heap.
 918       result = humongous_obj_allocate(word_size, AllocationContext::current());
 919       if (result != NULL) {
 920         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 921         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 922         return result;
 923       }
 924 
 925       // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
 926       // the GCLocker initiated GC has been performed and then retry. This includes
 927       // the case when the GC Locker is not active but has not been performed.
 928       should_try_gc = !GCLocker::needs_gc();
 929       // Read the GC count while still holding the Heap_lock.
 930       gc_count_before = total_collections();
 931     }
 932 
 933     if (should_try_gc) {
 934       bool succeeded;
 935       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 936                                    GCCause::_g1_humongous_allocation);
 937       if (result != NULL) {
 938         assert(succeeded, "only way to get back a non-NULL result");
 939         log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
 940                              Thread::current()->name(), p2i(result));
 941         return result;
 942       }
 943 
 944       if (succeeded) {
 945         // We successfully scheduled a collection which failed to allocate. No
 946         // point in trying to allocate further. We'll just return NULL.
 947         log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
 948                              SIZE_FORMAT " words", Thread::current()->name(), word_size);
 949         return NULL;
 950       }
 951       log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
 952                            Thread::current()->name(), word_size);
 953     } else {
 954       // Failed to schedule a collection.
 955       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 956         log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
 957                                SIZE_FORMAT " words", Thread::current()->name(), word_size);
 958         return NULL;
 959       }
 960       log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
 961       // The GCLocker is either active or the GCLocker initiated
 962       // GC has not yet been performed. Stall until it is and
 963       // then retry the allocation.
 964       GCLocker::stall_until_clear();
 965       gclocker_retry_count += 1;
 966     }
 967 
 968 
 969     // We can reach here if we were unsuccessful in scheduling a
 970     // collection (because another thread beat us to it) or if we were
 971     // stalled due to the GC locker. In either can we should retry the
 972     // allocation attempt in case another thread successfully
 973     // performed a collection and reclaimed enough space.
 974     // Humongous object allocation always needs a lock, so we wait for the retry
 975     // in the next iteration of the loop, unlike for the regular iteration case.
 976     // Give a warning if we seem to be looping forever.
 977 
 978     if ((QueuedAllocationWarningCount > 0) &&
 979         (try_count % QueuedAllocationWarningCount == 0)) {
 980       log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
 981                              Thread::current()->name(), try_count, word_size);
 982     }
 983   }
 984 
 985   ShouldNotReachHere();
 986   return NULL;
 987 }
 988 
 989 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
 990                                                            AllocationContext_t context,
 991                                                            bool expect_null_mutator_alloc_region) {
 992   assert_at_safepoint(true /* should_be_vm_thread */);
 993   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
 994          "the current alloc region was unexpectedly found to be non-NULL");
 995 
 996   if (!is_humongous(word_size)) {
 997     return _allocator->attempt_allocation_locked(word_size, context);
 998   } else {
 999     HeapWord* result = humongous_obj_allocate(word_size, context);
1000     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1001       collector_state()->set_initiate_conc_mark_if_possible(true);
1002     }
1003     return result;
1004   }
1005 
1006   ShouldNotReachHere();
1007 }
1008 
1009 class PostCompactionPrinterClosure: public HeapRegionClosure {
1010 private:
1011   G1HRPrinter* _hr_printer;
1012 public:
1013   bool do_heap_region(HeapRegion* hr) {
1014     assert(!hr->is_young(), "not expecting to find young regions");
1015     _hr_printer->post_compaction(hr);
1016     return false;
1017   }
1018 
1019   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1020     : _hr_printer(hr_printer) { }
1021 };
1022 
1023 void G1CollectedHeap::print_hrm_post_compaction() {
1024   if (_hr_printer.is_active()) {
1025     PostCompactionPrinterClosure cl(hr_printer());
1026     heap_region_iterate(&cl);
1027   }
1028 }
1029 
1030 void G1CollectedHeap::abort_concurrent_cycle() {
1031   // Note: When we have a more flexible GC logging framework that
1032   // allows us to add optional attributes to a GC log record we
1033   // could consider timing and reporting how long we wait in the
1034   // following two methods.
1035   wait_while_free_regions_coming();
1036   // If we start the compaction before the CM threads finish
1037   // scanning the root regions we might trip them over as we'll
1038   // be moving objects / updating references. So let's wait until
1039   // they are done. By telling them to abort, they should complete
1040   // early.
1041   _cm->root_regions()->abort();
1042   _cm->root_regions()->wait_until_scan_finished();
1043   append_secondary_free_list_if_not_empty_with_lock();
1044 
1045   // Disable discovery and empty the discovered lists
1046   // for the CM ref processor.
1047   ref_processor_cm()->disable_discovery();
1048   ref_processor_cm()->abandon_partial_discovery();
1049   ref_processor_cm()->verify_no_references_recorded();
1050 
1051   // Abandon current iterations of concurrent marking and concurrent
1052   // refinement, if any are in progress.
1053   concurrent_mark()->abort();
1054 }
1055 
1056 void G1CollectedHeap::prepare_heap_for_full_collection() {
1057   // Make sure we'll choose a new allocation region afterwards.
1058   _allocator->release_mutator_alloc_region();
1059   _allocator->abandon_gc_alloc_regions();
1060   g1_rem_set()->cleanupHRRS();
1061 
1062   // We may have added regions to the current incremental collection
1063   // set between the last GC or pause and now. We need to clear the
1064   // incremental collection set and then start rebuilding it afresh
1065   // after this full GC.
1066   abandon_collection_set(collection_set());
1067 
1068   tear_down_region_sets(false /* free_list_only */);
1069   collector_state()->set_gcs_are_young(true);
1070 }
1071 
1072 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1073   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1074   assert(used() == recalculate_used(), "Should be equal");
1075   _verifier->verify_region_sets_optional();
1076   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1077   _verifier->check_bitmaps("Full GC Start");
1078 }
1079 
1080 void G1CollectedHeap::prepare_heap_for_mutators() {
1081   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1082   ClassLoaderDataGraph::purge();
1083   MetaspaceAux::verify_metrics();
1084 
1085   // Prepare heap for normal collections.
1086   assert(num_free_regions() == 0, "we should not have added any free regions");
1087   rebuild_region_sets(false /* free_list_only */);
1088   abort_refinement();
1089   resize_if_necessary_after_full_collection();
1090 
1091   // Rebuild the strong code root lists for each region
1092   rebuild_strong_code_roots();
1093 
1094   // Start a new incremental collection set for the next pause
1095   start_new_collection_set();
1096 
1097   _allocator->init_mutator_alloc_region();
1098 
1099   // Post collection state updates.
1100   MetaspaceGC::compute_new_size();
1101 }
1102 
1103 void G1CollectedHeap::abort_refinement() {
1104   if (_hot_card_cache->use_cache()) {
1105     _hot_card_cache->reset_hot_cache();
1106   }
1107 
1108   // Discard all remembered set updates.
1109   JavaThread::dirty_card_queue_set().abandon_logs();
1110   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1111 }
1112 
1113 void G1CollectedHeap::verify_after_full_collection() {
1114   check_gc_time_stamps();
1115   _hrm.verify_optional();
1116   _verifier->verify_region_sets_optional();
1117   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1118   // Clear the previous marking bitmap, if needed for bitmap verification.
1119   // Note we cannot do this when we clear the next marking bitmap in
1120   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1121   // objects marked during a full GC against the previous bitmap.
1122   // But we need to clear it before calling check_bitmaps below since
1123   // the full GC has compacted objects and updated TAMS but not updated
1124   // the prev bitmap.
1125   if (G1VerifyBitmaps) {
1126     GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1127     _cm->clear_prev_bitmap(workers());
1128   }
1129   _verifier->check_bitmaps("Full GC End");
1130 
1131   // At this point there should be no regions in the
1132   // entire heap tagged as young.
1133   assert(check_young_list_empty(), "young list should be empty at this point");
1134 
1135   // Note: since we've just done a full GC, concurrent
1136   // marking is no longer active. Therefore we need not
1137   // re-enable reference discovery for the CM ref processor.
1138   // That will be done at the start of the next marking cycle.
1139   // We also know that the STW processor should no longer
1140   // discover any new references.
1141   assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1142   assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1143   ref_processor_stw()->verify_no_references_recorded();
1144   ref_processor_cm()->verify_no_references_recorded();
1145 }
1146 
1147 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1148   // Post collection logging.
1149   // We should do this after we potentially resize the heap so
1150   // that all the COMMIT / UNCOMMIT events are generated before
1151   // the compaction events.
1152   print_hrm_post_compaction();
1153   heap_transition->print();
1154   print_heap_after_gc();
1155   print_heap_regions();
1156 #ifdef TRACESPINNING
1157   ParallelTaskTerminator::print_termination_counts();
1158 #endif
1159 }
1160 
1161 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1162                                          bool clear_all_soft_refs) {
1163   assert_at_safepoint(true /* should_be_vm_thread */);
1164 
1165   if (GCLocker::check_active_before_gc()) {
1166     // Full GC was not completed.
1167     return false;
1168   }
1169 
1170   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1171       collector_policy()->should_clear_all_soft_refs();
1172 
1173   G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1174   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1175 
1176   collector.prepare_collection();
1177   collector.collect();
1178   collector.complete_collection();
1179 
1180   // Full collection was successfully completed.
1181   return true;
1182 }
1183 
1184 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1185   // Currently, there is no facility in the do_full_collection(bool) API to notify
1186   // the caller that the collection did not succeed (e.g., because it was locked
1187   // out by the GC locker). So, right now, we'll ignore the return value.
1188   bool dummy = do_full_collection(true,                /* explicit_gc */
1189                                   clear_all_soft_refs);
1190 }
1191 
1192 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1193   // Capacity, free and used after the GC counted as full regions to
1194   // include the waste in the following calculations.
1195   const size_t capacity_after_gc = capacity();
1196   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1197 
1198   // This is enforced in arguments.cpp.
1199   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1200          "otherwise the code below doesn't make sense");
1201 
1202   // We don't have floating point command-line arguments
1203   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1204   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1205   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1206   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1207 
1208   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1209   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1210 
1211   // We have to be careful here as these two calculations can overflow
1212   // 32-bit size_t's.
1213   double used_after_gc_d = (double) used_after_gc;
1214   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1215   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1216 
1217   // Let's make sure that they are both under the max heap size, which
1218   // by default will make them fit into a size_t.
1219   double desired_capacity_upper_bound = (double) max_heap_size;
1220   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1221                                     desired_capacity_upper_bound);
1222   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1223                                     desired_capacity_upper_bound);
1224 
1225   // We can now safely turn them into size_t's.
1226   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1227   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1228 
1229   // This assert only makes sense here, before we adjust them
1230   // with respect to the min and max heap size.
1231   assert(minimum_desired_capacity <= maximum_desired_capacity,
1232          "minimum_desired_capacity = " SIZE_FORMAT ", "
1233          "maximum_desired_capacity = " SIZE_FORMAT,
1234          minimum_desired_capacity, maximum_desired_capacity);
1235 
1236   // Should not be greater than the heap max size. No need to adjust
1237   // it with respect to the heap min size as it's a lower bound (i.e.,
1238   // we'll try to make the capacity larger than it, not smaller).
1239   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1240   // Should not be less than the heap min size. No need to adjust it
1241   // with respect to the heap max size as it's an upper bound (i.e.,
1242   // we'll try to make the capacity smaller than it, not greater).
1243   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1244 
1245   if (capacity_after_gc < minimum_desired_capacity) {
1246     // Don't expand unless it's significant
1247     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1248 
1249     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1250                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1251                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1252                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1253 
1254     expand(expand_bytes, _workers);
1255 
1256     // No expansion, now see if we want to shrink
1257   } else if (capacity_after_gc > maximum_desired_capacity) {
1258     // Capacity too large, compute shrinking size
1259     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1260 
1261     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1262                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1263                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1264                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1265 
1266     shrink(shrink_bytes);
1267   }
1268 }
1269 
1270 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1271                                                             AllocationContext_t context,
1272                                                             bool do_gc,
1273                                                             bool clear_all_soft_refs,
1274                                                             bool expect_null_mutator_alloc_region,
1275                                                             bool* gc_succeeded) {
1276   *gc_succeeded = true;
1277   // Let's attempt the allocation first.
1278   HeapWord* result =
1279     attempt_allocation_at_safepoint(word_size,
1280                                     context,
1281                                     expect_null_mutator_alloc_region);
1282   if (result != NULL) {
1283     return result;
1284   }
1285 
1286   // In a G1 heap, we're supposed to keep allocation from failing by
1287   // incremental pauses.  Therefore, at least for now, we'll favor
1288   // expansion over collection.  (This might change in the future if we can
1289   // do something smarter than full collection to satisfy a failed alloc.)
1290   result = expand_and_allocate(word_size, context);
1291   if (result != NULL) {
1292     return result;
1293   }
1294 
1295   if (do_gc) {
1296     // Expansion didn't work, we'll try to do a Full GC.
1297     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1298                                        clear_all_soft_refs);
1299   }
1300 
1301   return NULL;
1302 }
1303 
1304 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1305                                                      AllocationContext_t context,
1306                                                      bool* succeeded) {
1307   assert_at_safepoint(true /* should_be_vm_thread */);
1308 
1309   // Attempts to allocate followed by Full GC.
1310   HeapWord* result =
1311     satisfy_failed_allocation_helper(word_size,
1312                                      context,
1313                                      true,  /* do_gc */
1314                                      false, /* clear_all_soft_refs */
1315                                      false, /* expect_null_mutator_alloc_region */
1316                                      succeeded);
1317 
1318   if (result != NULL || !*succeeded) {
1319     return result;
1320   }
1321 
1322   // Attempts to allocate followed by Full GC that will collect all soft references.
1323   result = satisfy_failed_allocation_helper(word_size,
1324                                             context,
1325                                             true, /* do_gc */
1326                                             true, /* clear_all_soft_refs */
1327                                             true, /* expect_null_mutator_alloc_region */
1328                                             succeeded);
1329 
1330   if (result != NULL || !*succeeded) {
1331     return result;
1332   }
1333 
1334   // Attempts to allocate, no GC
1335   result = satisfy_failed_allocation_helper(word_size,
1336                                             context,
1337                                             false, /* do_gc */
1338                                             false, /* clear_all_soft_refs */
1339                                             true,  /* expect_null_mutator_alloc_region */
1340                                             succeeded);
1341 
1342   if (result != NULL) {
1343     return result;
1344   }
1345 
1346   assert(!collector_policy()->should_clear_all_soft_refs(),
1347          "Flag should have been handled and cleared prior to this point");
1348 
1349   // What else?  We might try synchronous finalization later.  If the total
1350   // space available is large enough for the allocation, then a more
1351   // complete compaction phase than we've tried so far might be
1352   // appropriate.
1353   return NULL;
1354 }
1355 
1356 // Attempting to expand the heap sufficiently
1357 // to support an allocation of the given "word_size".  If
1358 // successful, perform the allocation and return the address of the
1359 // allocated block, or else "NULL".
1360 
1361 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1362   assert_at_safepoint(true /* should_be_vm_thread */);
1363 
1364   _verifier->verify_region_sets_optional();
1365 
1366   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1367   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1368                             word_size * HeapWordSize);
1369 
1370 
1371   if (expand(expand_bytes, _workers)) {
1372     _hrm.verify_optional();
1373     _verifier->verify_region_sets_optional();
1374     return attempt_allocation_at_safepoint(word_size,
1375                                            context,
1376                                            false /* expect_null_mutator_alloc_region */);
1377   }
1378   return NULL;
1379 }
1380 
1381 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1382   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1383   aligned_expand_bytes = align_up(aligned_expand_bytes,
1384                                        HeapRegion::GrainBytes);
1385 
1386   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1387                             expand_bytes, aligned_expand_bytes);
1388 
1389   if (is_maximal_no_gc()) {
1390     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1391     return false;
1392   }
1393 
1394   double expand_heap_start_time_sec = os::elapsedTime();
1395   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1396   assert(regions_to_expand > 0, "Must expand by at least one region");
1397 
1398   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1399   if (expand_time_ms != NULL) {
1400     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1401   }
1402 
1403   if (expanded_by > 0) {
1404     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1405     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1406     g1_policy()->record_new_heap_size(num_regions());
1407   } else {
1408     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1409 
1410     // The expansion of the virtual storage space was unsuccessful.
1411     // Let's see if it was because we ran out of swap.
1412     if (G1ExitOnExpansionFailure &&
1413         _hrm.available() >= regions_to_expand) {
1414       // We had head room...
1415       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1416     }
1417   }
1418   return regions_to_expand > 0;
1419 }
1420 
1421 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1422   size_t aligned_shrink_bytes =
1423     ReservedSpace::page_align_size_down(shrink_bytes);
1424   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1425                                          HeapRegion::GrainBytes);
1426   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1427 
1428   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1429   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1430 
1431 
1432   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",
1433                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1434   if (num_regions_removed > 0) {
1435     g1_policy()->record_new_heap_size(num_regions());
1436   } else {
1437     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1438   }
1439 }
1440 
1441 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1442   _verifier->verify_region_sets_optional();
1443 
1444   // We should only reach here at the end of a Full GC which means we
1445   // should not not be holding to any GC alloc regions. The method
1446   // below will make sure of that and do any remaining clean up.
1447   _allocator->abandon_gc_alloc_regions();
1448 
1449   // Instead of tearing down / rebuilding the free lists here, we
1450   // could instead use the remove_all_pending() method on free_list to
1451   // remove only the ones that we need to remove.
1452   tear_down_region_sets(true /* free_list_only */);
1453   shrink_helper(shrink_bytes);
1454   rebuild_region_sets(true /* free_list_only */);
1455 
1456   _hrm.verify_optional();
1457   _verifier->verify_region_sets_optional();
1458 }
1459 
1460 // Public methods.
1461 
1462 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1463   CollectedHeap(),
1464   _young_gen_sampling_thread(NULL),
1465   _collector_policy(collector_policy),
1466   _memory_manager("G1 Young Generation", "end of minor GC"),
1467   _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1468   _eden_pool(NULL),
1469   _survivor_pool(NULL),
1470   _old_pool(NULL),
1471   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1472   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1473   _g1_policy(create_g1_policy(_gc_timer_stw)),
1474   _collection_set(this, _g1_policy),
1475   _dirty_card_queue_set(false),
1476   _is_alive_closure_cm(this),
1477   _is_alive_closure_stw(this),
1478   _ref_processor_cm(NULL),
1479   _ref_processor_stw(NULL),
1480   _bot(NULL),
1481   _hot_card_cache(NULL),
1482   _g1_rem_set(NULL),
1483   _cr(NULL),
1484   _g1mm(NULL),
1485   _preserved_marks_set(true /* in_c_heap */),
1486   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1487   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1488   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1489   _humongous_reclaim_candidates(),
1490   _has_humongous_reclaim_candidates(false),
1491   _archive_allocator(NULL),
1492   _free_regions_coming(false),
1493   _gc_time_stamp(0),
1494   _summary_bytes_used(0),
1495   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1496   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1497   _expand_heap_after_alloc_failure(true),
1498   _old_marking_cycles_started(0),
1499   _old_marking_cycles_completed(0),
1500   _in_cset_fast_test() {
1501 
1502   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1503                           /* are_GC_task_threads */true,
1504                           /* are_ConcurrentGC_threads */false);
1505   _workers->initialize_workers();
1506   _verifier = new G1HeapVerifier(this);
1507 
1508   _allocator = G1Allocator::create_allocator(this);
1509 
1510   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1511 
1512   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1513 
1514   // Override the default _filler_array_max_size so that no humongous filler
1515   // objects are created.
1516   _filler_array_max_size = _humongous_object_threshold_in_words;
1517 
1518   uint n_queues = ParallelGCThreads;
1519   _task_queues = new RefToScanQueueSet(n_queues);
1520 
1521   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1522 
1523   for (uint i = 0; i < n_queues; i++) {
1524     RefToScanQueue* q = new RefToScanQueue();
1525     q->initialize();
1526     _task_queues->register_queue(i, q);
1527     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1528   }
1529 
1530   // Initialize the G1EvacuationFailureALot counters and flags.
1531   NOT_PRODUCT(reset_evacuation_should_fail();)
1532 
1533   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1534 }
1535 
1536 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1537                                                                  size_t size,
1538                                                                  size_t translation_factor) {
1539   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1540   // Allocate a new reserved space, preferring to use large pages.
1541   ReservedSpace rs(size, preferred_page_size);
1542   G1RegionToSpaceMapper* result  =
1543     G1RegionToSpaceMapper::create_mapper(rs,
1544                                          size,
1545                                          rs.alignment(),
1546                                          HeapRegion::GrainBytes,
1547                                          translation_factor,
1548                                          mtGC);
1549 
1550   os::trace_page_sizes_for_requested_size(description,
1551                                           size,
1552                                           preferred_page_size,
1553                                           rs.alignment(),
1554                                           rs.base(),
1555                                           rs.size());
1556 
1557   return result;
1558 }
1559 
1560 jint G1CollectedHeap::initialize_concurrent_refinement() {
1561   jint ecode = JNI_OK;
1562   _cr = G1ConcurrentRefine::create(&ecode);
1563   return ecode;
1564 }
1565 
1566 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1567   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1568   if (_young_gen_sampling_thread->osthread() == NULL) {
1569     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1570     return JNI_ENOMEM;
1571   }
1572   return JNI_OK;
1573 }
1574 
1575 jint G1CollectedHeap::initialize() {
1576   os::enable_vtime();
1577 
1578   // Necessary to satisfy locking discipline assertions.
1579 
1580   MutexLocker x(Heap_lock);
1581 
1582   // While there are no constraints in the GC code that HeapWordSize
1583   // be any particular value, there are multiple other areas in the
1584   // system which believe this to be true (e.g. oop->object_size in some
1585   // cases incorrectly returns the size in wordSize units rather than
1586   // HeapWordSize).
1587   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1588 
1589   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1590   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1591   size_t heap_alignment = collector_policy()->heap_alignment();
1592 
1593   // Ensure that the sizes are properly aligned.
1594   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1595   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1596   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1597 
1598   // Reserve the maximum.
1599 
1600   // When compressed oops are enabled, the preferred heap base
1601   // is calculated by subtracting the requested size from the
1602   // 32Gb boundary and using the result as the base address for
1603   // heap reservation. If the requested size is not aligned to
1604   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1605   // into the ReservedHeapSpace constructor) then the actual
1606   // base of the reserved heap may end up differing from the
1607   // address that was requested (i.e. the preferred heap base).
1608   // If this happens then we could end up using a non-optimal
1609   // compressed oops mode.
1610 
1611   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1612                                                  heap_alignment);
1613 
1614   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1615 
1616   // Create the barrier set for the entire reserved region.
1617   G1SATBCardTableLoggingModRefBS* bs
1618     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1619   bs->initialize();
1620   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1621   set_barrier_set(bs);
1622 
1623   // Create the hot card cache.
1624   _hot_card_cache = new G1HotCardCache(this);
1625 
1626   // Carve out the G1 part of the heap.
1627   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1628   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1629   G1RegionToSpaceMapper* heap_storage =
1630     G1RegionToSpaceMapper::create_mapper(g1_rs,
1631                                          g1_rs.size(),
1632                                          page_size,
1633                                          HeapRegion::GrainBytes,
1634                                          1,
1635                                          mtJavaHeap);
1636   os::trace_page_sizes("Heap",
1637                        collector_policy()->min_heap_byte_size(),
1638                        max_byte_size,
1639                        page_size,
1640                        heap_rs.base(),
1641                        heap_rs.size());
1642   heap_storage->set_mapping_changed_listener(&_listener);
1643 
1644   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1645   G1RegionToSpaceMapper* bot_storage =
1646     create_aux_memory_mapper("Block Offset Table",
1647                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1648                              G1BlockOffsetTable::heap_map_factor());
1649 
1650   G1RegionToSpaceMapper* cardtable_storage =
1651     create_aux_memory_mapper("Card Table",
1652                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1653                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1654 
1655   G1RegionToSpaceMapper* card_counts_storage =
1656     create_aux_memory_mapper("Card Counts Table",
1657                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1658                              G1CardCounts::heap_map_factor());
1659 
1660   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1661   G1RegionToSpaceMapper* prev_bitmap_storage =
1662     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1663   G1RegionToSpaceMapper* next_bitmap_storage =
1664     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1665 
1666   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1667   g1_barrier_set()->initialize(cardtable_storage);
1668   // Do later initialization work for concurrent refinement.
1669   _hot_card_cache->initialize(card_counts_storage);
1670 
1671   // 6843694 - ensure that the maximum region index can fit
1672   // in the remembered set structures.
1673   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1674   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1675 
1676   // Also create a G1 rem set.
1677   _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1678   _g1_rem_set->initialize(max_capacity(), max_regions());
1679 
1680   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1681   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1682   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1683             "too many cards per region");
1684 
1685   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1686 
1687   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1688 
1689   {
1690     HeapWord* start = _hrm.reserved().start();
1691     HeapWord* end = _hrm.reserved().end();
1692     size_t granularity = HeapRegion::GrainBytes;
1693 
1694     _in_cset_fast_test.initialize(start, end, granularity);
1695     _humongous_reclaim_candidates.initialize(start, end, granularity);
1696   }
1697 
1698   // Create the G1ConcurrentMark data structure and thread.
1699   // (Must do this late, so that "max_regions" is defined.)
1700   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1701   if (_cm == NULL || !_cm->completed_initialization()) {
1702     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1703     return JNI_ENOMEM;
1704   }
1705   _cmThread = _cm->cm_thread();
1706 
1707   // Now expand into the initial heap size.
1708   if (!expand(init_byte_size, _workers)) {
1709     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1710     return JNI_ENOMEM;
1711   }
1712 
1713   // Perform any initialization actions delegated to the policy.
1714   g1_policy()->init(this, &_collection_set);
1715 
1716   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1717                                                SATB_Q_FL_lock,
1718                                                G1SATBProcessCompletedThreshold,
1719                                                Shared_SATB_Q_lock);
1720 
1721   jint ecode = initialize_concurrent_refinement();
1722   if (ecode != JNI_OK) {
1723     return ecode;
1724   }
1725 
1726   ecode = initialize_young_gen_sampling_thread();
1727   if (ecode != JNI_OK) {
1728     return ecode;
1729   }
1730 
1731   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1732                                                 DirtyCardQ_FL_lock,
1733                                                 (int)concurrent_refine()->yellow_zone(),
1734                                                 (int)concurrent_refine()->red_zone(),
1735                                                 Shared_DirtyCardQ_lock,
1736                                                 NULL,  // fl_owner
1737                                                 true); // init_free_ids
1738 
1739   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1740                                     DirtyCardQ_FL_lock,
1741                                     -1, // never trigger processing
1742                                     -1, // no limit on length
1743                                     Shared_DirtyCardQ_lock,
1744                                     &JavaThread::dirty_card_queue_set());
1745 
1746   // Here we allocate the dummy HeapRegion that is required by the
1747   // G1AllocRegion class.
1748   HeapRegion* dummy_region = _hrm.get_dummy_region();
1749 
1750   // We'll re-use the same region whether the alloc region will
1751   // require BOT updates or not and, if it doesn't, then a non-young
1752   // region will complain that it cannot support allocations without
1753   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1754   dummy_region->set_eden();
1755   // Make sure it's full.
1756   dummy_region->set_top(dummy_region->end());
1757   G1AllocRegion::setup(this, dummy_region);
1758 
1759   _allocator->init_mutator_alloc_region();
1760 
1761   // Do create of the monitoring and management support so that
1762   // values in the heap have been properly initialized.
1763   _g1mm = new G1MonitoringSupport(this);
1764 
1765   G1StringDedup::initialize();
1766 
1767   _preserved_marks_set.init(ParallelGCThreads);
1768 
1769   _collection_set.initialize(max_regions());
1770 
1771   return JNI_OK;
1772 }
1773 
1774 void G1CollectedHeap::initialize_serviceability() {
1775   _eden_pool = new G1EdenPool(this);
1776   _survivor_pool = new G1SurvivorPool(this);
1777   _old_pool = new G1OldGenPool(this);
1778 
1779   _full_gc_memory_manager.add_pool(_eden_pool);
1780   _full_gc_memory_manager.add_pool(_survivor_pool);
1781   _full_gc_memory_manager.add_pool(_old_pool);
1782 
1783   _memory_manager.add_pool(_eden_pool);
1784   _memory_manager.add_pool(_survivor_pool);
1785 
1786 }
1787 
1788 void G1CollectedHeap::stop() {
1789   // Stop all concurrent threads. We do this to make sure these threads
1790   // do not continue to execute and access resources (e.g. logging)
1791   // that are destroyed during shutdown.
1792   _cr->stop();
1793   _young_gen_sampling_thread->stop();
1794   _cmThread->stop();
1795   if (G1StringDedup::is_enabled()) {
1796     G1StringDedup::stop();
1797   }
1798 }
1799 
1800 void G1CollectedHeap::safepoint_synchronize_begin() {
1801   SuspendibleThreadSet::synchronize();
1802 }
1803 
1804 void G1CollectedHeap::safepoint_synchronize_end() {
1805   SuspendibleThreadSet::desynchronize();
1806 }
1807 
1808 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1809   return HeapRegion::max_region_size();
1810 }
1811 
1812 void G1CollectedHeap::post_initialize() {
1813   CollectedHeap::post_initialize();
1814   ref_processing_init();
1815 }
1816 
1817 void G1CollectedHeap::ref_processing_init() {
1818   // Reference processing in G1 currently works as follows:
1819   //
1820   // * There are two reference processor instances. One is
1821   //   used to record and process discovered references
1822   //   during concurrent marking; the other is used to
1823   //   record and process references during STW pauses
1824   //   (both full and incremental).
1825   // * Both ref processors need to 'span' the entire heap as
1826   //   the regions in the collection set may be dotted around.
1827   //
1828   // * For the concurrent marking ref processor:
1829   //   * Reference discovery is enabled at initial marking.
1830   //   * Reference discovery is disabled and the discovered
1831   //     references processed etc during remarking.
1832   //   * Reference discovery is MT (see below).
1833   //   * Reference discovery requires a barrier (see below).
1834   //   * Reference processing may or may not be MT
1835   //     (depending on the value of ParallelRefProcEnabled
1836   //     and ParallelGCThreads).
1837   //   * A full GC disables reference discovery by the CM
1838   //     ref processor and abandons any entries on it's
1839   //     discovered lists.
1840   //
1841   // * For the STW processor:
1842   //   * Non MT discovery is enabled at the start of a full GC.
1843   //   * Processing and enqueueing during a full GC is non-MT.
1844   //   * During a full GC, references are processed after marking.
1845   //
1846   //   * Discovery (may or may not be MT) is enabled at the start
1847   //     of an incremental evacuation pause.
1848   //   * References are processed near the end of a STW evacuation pause.
1849   //   * For both types of GC:
1850   //     * Discovery is atomic - i.e. not concurrent.
1851   //     * Reference discovery will not need a barrier.
1852 
1853   MemRegion mr = reserved_region();
1854 
1855   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1856 
1857   // Concurrent Mark ref processor
1858   _ref_processor_cm =
1859     new ReferenceProcessor(mr,    // span
1860                            mt_processing,
1861                                 // mt processing
1862                            ParallelGCThreads,
1863                                 // degree of mt processing
1864                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1865                                 // mt discovery
1866                            MAX2(ParallelGCThreads, ConcGCThreads),
1867                                 // degree of mt discovery
1868                            false,
1869                                 // Reference discovery is not atomic
1870                            &_is_alive_closure_cm);
1871                                 // is alive closure
1872                                 // (for efficiency/performance)
1873 
1874   // STW ref processor
1875   _ref_processor_stw =
1876     new ReferenceProcessor(mr,    // span
1877                            mt_processing,
1878                                 // mt processing
1879                            ParallelGCThreads,
1880                                 // degree of mt processing
1881                            (ParallelGCThreads > 1),
1882                                 // mt discovery
1883                            ParallelGCThreads,
1884                                 // degree of mt discovery
1885                            true,
1886                                 // Reference discovery is atomic
1887                            &_is_alive_closure_stw);
1888                                 // is alive closure
1889                                 // (for efficiency/performance)
1890 }
1891 
1892 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1893   return _collector_policy;
1894 }
1895 
1896 size_t G1CollectedHeap::capacity() const {
1897   return _hrm.length() * HeapRegion::GrainBytes;
1898 }
1899 
1900 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1901   return _hrm.total_free_bytes();
1902 }
1903 
1904 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1905   hr->reset_gc_time_stamp();
1906 }
1907 
1908 #ifndef PRODUCT
1909 
1910 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1911 private:
1912   unsigned _gc_time_stamp;
1913   bool _failures;
1914 
1915 public:
1916   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1917     _gc_time_stamp(gc_time_stamp), _failures(false) { }
1918 
1919   virtual bool do_heap_region(HeapRegion* hr) {
1920     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1921     if (_gc_time_stamp != region_gc_time_stamp) {
1922       log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1923                             region_gc_time_stamp, _gc_time_stamp);
1924       _failures = true;
1925     }
1926     return false;
1927   }
1928 
1929   bool failures() { return _failures; }
1930 };
1931 
1932 void G1CollectedHeap::check_gc_time_stamps() {
1933   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1934   heap_region_iterate(&cl);
1935   guarantee(!cl.failures(), "all GC time stamps should have been reset");
1936 }
1937 #endif // PRODUCT
1938 
1939 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1940   _hot_card_cache->drain(cl, worker_i);
1941 }
1942 
1943 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1944   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1945   size_t n_completed_buffers = 0;
1946   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1947     n_completed_buffers++;
1948   }
1949   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1950   dcqs.clear_n_completed_buffers();
1951   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1952 }
1953 
1954 // Computes the sum of the storage used by the various regions.
1955 size_t G1CollectedHeap::used() const {
1956   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1957   if (_archive_allocator != NULL) {
1958     result += _archive_allocator->used();
1959   }
1960   return result;
1961 }
1962 
1963 size_t G1CollectedHeap::used_unlocked() const {
1964   return _summary_bytes_used;
1965 }
1966 
1967 class SumUsedClosure: public HeapRegionClosure {
1968   size_t _used;
1969 public:
1970   SumUsedClosure() : _used(0) {}
1971   bool do_heap_region(HeapRegion* r) {
1972     _used += r->used();
1973     return false;
1974   }
1975   size_t result() { return _used; }
1976 };
1977 
1978 size_t G1CollectedHeap::recalculate_used() const {
1979   double recalculate_used_start = os::elapsedTime();
1980 
1981   SumUsedClosure blk;
1982   heap_region_iterate(&blk);
1983 
1984   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1985   return blk.result();
1986 }
1987 
1988 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1989   switch (cause) {
1990     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
1991     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
1992     case GCCause::_update_allocation_context_stats_inc: return true;
1993     case GCCause::_wb_conc_mark:                        return true;
1994     default :                                           return false;
1995   }
1996 }
1997 
1998 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1999   switch (cause) {
2000     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2001     case GCCause::_g1_humongous_allocation: return true;
2002     default:                                return is_user_requested_concurrent_full_gc(cause);
2003   }
2004 }
2005 
2006 #ifndef PRODUCT
2007 void G1CollectedHeap::allocate_dummy_regions() {
2008   // Let's fill up most of the region
2009   size_t word_size = HeapRegion::GrainWords - 1024;
2010   // And as a result the region we'll allocate will be humongous.
2011   guarantee(is_humongous(word_size), "sanity");
2012 
2013   // _filler_array_max_size is set to humongous object threshold
2014   // but temporarily change it to use CollectedHeap::fill_with_object().
2015   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2016 
2017   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2018     // Let's use the existing mechanism for the allocation
2019     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2020                                                  AllocationContext::system());
2021     if (dummy_obj != NULL) {
2022       MemRegion mr(dummy_obj, word_size);
2023       CollectedHeap::fill_with_object(mr);
2024     } else {
2025       // If we can't allocate once, we probably cannot allocate
2026       // again. Let's get out of the loop.
2027       break;
2028     }
2029   }
2030 }
2031 #endif // !PRODUCT
2032 
2033 void G1CollectedHeap::increment_old_marking_cycles_started() {
2034   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2035          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2036          "Wrong marking cycle count (started: %d, completed: %d)",
2037          _old_marking_cycles_started, _old_marking_cycles_completed);
2038 
2039   _old_marking_cycles_started++;
2040 }
2041 
2042 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2043   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2044 
2045   // We assume that if concurrent == true, then the caller is a
2046   // concurrent thread that was joined the Suspendible Thread
2047   // Set. If there's ever a cheap way to check this, we should add an
2048   // assert here.
2049 
2050   // Given that this method is called at the end of a Full GC or of a
2051   // concurrent cycle, and those can be nested (i.e., a Full GC can
2052   // interrupt a concurrent cycle), the number of full collections
2053   // completed should be either one (in the case where there was no
2054   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2055   // behind the number of full collections started.
2056 
2057   // This is the case for the inner caller, i.e. a Full GC.
2058   assert(concurrent ||
2059          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2060          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2061          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2062          "is inconsistent with _old_marking_cycles_completed = %u",
2063          _old_marking_cycles_started, _old_marking_cycles_completed);
2064 
2065   // This is the case for the outer caller, i.e. the concurrent cycle.
2066   assert(!concurrent ||
2067          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2068          "for outer caller (concurrent cycle): "
2069          "_old_marking_cycles_started = %u "
2070          "is inconsistent with _old_marking_cycles_completed = %u",
2071          _old_marking_cycles_started, _old_marking_cycles_completed);
2072 
2073   _old_marking_cycles_completed += 1;
2074 
2075   // We need to clear the "in_progress" flag in the CM thread before
2076   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2077   // is set) so that if a waiter requests another System.gc() it doesn't
2078   // incorrectly see that a marking cycle is still in progress.
2079   if (concurrent) {
2080     _cmThread->set_idle();
2081   }
2082 
2083   // This notify_all() will ensure that a thread that called
2084   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2085   // and it's waiting for a full GC to finish will be woken up. It is
2086   // waiting in VM_G1CollectForAllocation::doit_epilogue().
2087   FullGCCount_lock->notify_all();
2088 }
2089 
2090 void G1CollectedHeap::collect(GCCause::Cause cause) {
2091   assert_heap_not_locked();
2092 
2093   uint gc_count_before;
2094   uint old_marking_count_before;
2095   uint full_gc_count_before;
2096   bool retry_gc;
2097 
2098   do {
2099     retry_gc = false;
2100 
2101     {
2102       MutexLocker ml(Heap_lock);
2103 
2104       // Read the GC count while holding the Heap_lock
2105       gc_count_before = total_collections();
2106       full_gc_count_before = total_full_collections();
2107       old_marking_count_before = _old_marking_cycles_started;
2108     }
2109 
2110     if (should_do_concurrent_full_gc(cause)) {
2111       // Schedule an initial-mark evacuation pause that will start a
2112       // concurrent cycle. We're setting word_size to 0 which means that
2113       // we are not requesting a post-GC allocation.
2114       VM_G1CollectForAllocation op(0,     /* word_size */
2115                                    gc_count_before,
2116                                    cause,
2117                                    true,  /* should_initiate_conc_mark */
2118                                    g1_policy()->max_pause_time_ms(),
2119                                    AllocationContext::current());
2120       VMThread::execute(&op);
2121       if (!op.pause_succeeded()) {
2122         if (old_marking_count_before == _old_marking_cycles_started) {
2123           retry_gc = op.should_retry_gc();
2124         } else {
2125           // A Full GC happened while we were trying to schedule the
2126           // initial-mark GC. No point in starting a new cycle given
2127           // that the whole heap was collected anyway.
2128         }
2129 
2130         if (retry_gc) {
2131           if (GCLocker::is_active_and_needs_gc()) {
2132             GCLocker::stall_until_clear();
2133           }
2134         }
2135       }
2136     } else {
2137       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2138           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2139 
2140         // Schedule a standard evacuation pause. We're setting word_size
2141         // to 0 which means that we are not requesting a post-GC allocation.
2142         VM_G1CollectForAllocation op(0,     /* word_size */
2143                                      gc_count_before,
2144                                      cause,
2145                                      false, /* should_initiate_conc_mark */
2146                                      g1_policy()->max_pause_time_ms(),
2147                                      AllocationContext::current());
2148         VMThread::execute(&op);
2149       } else {
2150         // Schedule a Full GC.
2151         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2152         VMThread::execute(&op);
2153       }
2154     }
2155   } while (retry_gc);
2156 }
2157 
2158 bool G1CollectedHeap::is_in(const void* p) const {
2159   if (_hrm.reserved().contains(p)) {
2160     // Given that we know that p is in the reserved space,
2161     // heap_region_containing() should successfully
2162     // return the containing region.
2163     HeapRegion* hr = heap_region_containing(p);
2164     return hr->is_in(p);
2165   } else {
2166     return false;
2167   }
2168 }
2169 
2170 #ifdef ASSERT
2171 bool G1CollectedHeap::is_in_exact(const void* p) const {
2172   bool contains = reserved_region().contains(p);
2173   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2174   if (contains && available) {
2175     return true;
2176   } else {
2177     return false;
2178   }
2179 }
2180 #endif
2181 
2182 // Iteration functions.
2183 
2184 // Iterates an ObjectClosure over all objects within a HeapRegion.
2185 
2186 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2187   ObjectClosure* _cl;
2188 public:
2189   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2190   bool do_heap_region(HeapRegion* r) {
2191     if (!r->is_continues_humongous()) {
2192       r->object_iterate(_cl);
2193     }
2194     return false;
2195   }
2196 };
2197 
2198 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2199   IterateObjectClosureRegionClosure blk(cl);
2200   heap_region_iterate(&blk);
2201 }
2202 
2203 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2204   _hrm.iterate(cl);
2205 }
2206 
2207 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2208                                                                  HeapRegionClaimer *hrclaimer,
2209                                                                  uint worker_id) const {
2210   _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2211 }
2212 
2213 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2214                                                          HeapRegionClaimer *hrclaimer) const {
2215   _hrm.par_iterate(cl, hrclaimer, 0);
2216 }
2217 
2218 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2219   _collection_set.iterate(cl);
2220 }
2221 
2222 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2223   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2224 }
2225 
2226 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2227   HeapRegion* hr = heap_region_containing(addr);
2228   return hr->block_start(addr);
2229 }
2230 
2231 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2232   HeapRegion* hr = heap_region_containing(addr);
2233   return hr->block_size(addr);
2234 }
2235 
2236 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2237   HeapRegion* hr = heap_region_containing(addr);
2238   return hr->block_is_obj(addr);
2239 }
2240 
2241 bool G1CollectedHeap::supports_tlab_allocation() const {
2242   return true;
2243 }
2244 
2245 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2246   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2247 }
2248 
2249 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2250   return _eden.length() * HeapRegion::GrainBytes;
2251 }
2252 
2253 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2254 // must be equal to the humongous object limit.
2255 size_t G1CollectedHeap::max_tlab_size() const {
2256   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2257 }
2258 
2259 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2260   AllocationContext_t context = AllocationContext::current();
2261   return _allocator->unsafe_max_tlab_alloc(context);
2262 }
2263 
2264 size_t G1CollectedHeap::max_capacity() const {
2265   return _hrm.reserved().byte_size();
2266 }
2267 
2268 jlong G1CollectedHeap::millis_since_last_gc() {
2269   // See the notes in GenCollectedHeap::millis_since_last_gc()
2270   // for more information about the implementation.
2271   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2272     _g1_policy->collection_pause_end_millis();
2273   if (ret_val < 0) {
2274     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2275       ". returning zero instead.", ret_val);
2276     return 0;
2277   }
2278   return ret_val;
2279 }
2280 
2281 void G1CollectedHeap::prepare_for_verify() {
2282   _verifier->prepare_for_verify();
2283 }
2284 
2285 void G1CollectedHeap::verify(VerifyOption vo) {
2286   _verifier->verify(vo);
2287 }
2288 
2289 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2290   return true;
2291 }
2292 
2293 const char* const* G1CollectedHeap::concurrent_phases() const {
2294   return _cmThread->concurrent_phases();
2295 }
2296 
2297 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2298   return _cmThread->request_concurrent_phase(phase);
2299 }
2300 
2301 class PrintRegionClosure: public HeapRegionClosure {
2302   outputStream* _st;
2303 public:
2304   PrintRegionClosure(outputStream* st) : _st(st) {}
2305   bool do_heap_region(HeapRegion* r) {
2306     r->print_on(_st);
2307     return false;
2308   }
2309 };
2310 
2311 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2312                                        const HeapRegion* hr,
2313                                        const VerifyOption vo) const {
2314   switch (vo) {
2315   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2316   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2317   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2318   default:                            ShouldNotReachHere();
2319   }
2320   return false; // keep some compilers happy
2321 }
2322 
2323 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2324                                        const VerifyOption vo) const {
2325   switch (vo) {
2326   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2327   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2328   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2329   default:                            ShouldNotReachHere();
2330   }
2331   return false; // keep some compilers happy
2332 }
2333 
2334 void G1CollectedHeap::print_heap_regions() const {
2335   LogTarget(Trace, gc, heap, region) lt;
2336   if (lt.is_enabled()) {
2337     LogStream ls(lt);
2338     print_regions_on(&ls);
2339   }
2340 }
2341 
2342 void G1CollectedHeap::print_on(outputStream* st) const {
2343   st->print(" %-20s", "garbage-first heap");
2344   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2345             capacity()/K, used_unlocked()/K);
2346   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2347             p2i(_hrm.reserved().start()),
2348             p2i(_hrm.reserved().end()));
2349   st->cr();
2350   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2351   uint young_regions = young_regions_count();
2352   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2353             (size_t) young_regions * HeapRegion::GrainBytes / K);
2354   uint survivor_regions = survivor_regions_count();
2355   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2356             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2357   st->cr();
2358   MetaspaceAux::print_on(st);
2359 }
2360 
2361 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2362   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2363                "HS=humongous(starts), HC=humongous(continues), "
2364                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2365                "AC=allocation context, "
2366                "TAMS=top-at-mark-start (previous, next)");
2367   PrintRegionClosure blk(st);
2368   heap_region_iterate(&blk);
2369 }
2370 
2371 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2372   print_on(st);
2373 
2374   // Print the per-region information.
2375   print_regions_on(st);
2376 }
2377 
2378 void G1CollectedHeap::print_on_error(outputStream* st) const {
2379   this->CollectedHeap::print_on_error(st);
2380 
2381   if (_cm != NULL) {
2382     st->cr();
2383     _cm->print_on_error(st);
2384   }
2385 }
2386 
2387 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2388   workers()->print_worker_threads_on(st);
2389   _cmThread->print_on(st);
2390   st->cr();
2391   _cm->print_worker_threads_on(st);
2392   _cr->print_threads_on(st);
2393   _young_gen_sampling_thread->print_on(st);
2394   if (G1StringDedup::is_enabled()) {
2395     G1StringDedup::print_worker_threads_on(st);
2396   }
2397 }
2398 
2399 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2400   workers()->threads_do(tc);
2401   tc->do_thread(_cmThread);
2402   _cm->threads_do(tc);
2403   _cr->threads_do(tc);
2404   tc->do_thread(_young_gen_sampling_thread);
2405   if (G1StringDedup::is_enabled()) {
2406     G1StringDedup::threads_do(tc);
2407   }
2408 }
2409 
2410 void G1CollectedHeap::print_tracing_info() const {
2411   g1_rem_set()->print_summary_info();
2412   concurrent_mark()->print_summary_info();
2413 }
2414 
2415 #ifndef PRODUCT
2416 // Helpful for debugging RSet issues.
2417 
2418 class PrintRSetsClosure : public HeapRegionClosure {
2419 private:
2420   const char* _msg;
2421   size_t _occupied_sum;
2422 
2423 public:
2424   bool do_heap_region(HeapRegion* r) {
2425     HeapRegionRemSet* hrrs = r->rem_set();
2426     size_t occupied = hrrs->occupied();
2427     _occupied_sum += occupied;
2428 
2429     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2430     if (occupied == 0) {
2431       tty->print_cr("  RSet is empty");
2432     } else {
2433       hrrs->print();
2434     }
2435     tty->print_cr("----------");
2436     return false;
2437   }
2438 
2439   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2440     tty->cr();
2441     tty->print_cr("========================================");
2442     tty->print_cr("%s", msg);
2443     tty->cr();
2444   }
2445 
2446   ~PrintRSetsClosure() {
2447     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2448     tty->print_cr("========================================");
2449     tty->cr();
2450   }
2451 };
2452 
2453 void G1CollectedHeap::print_cset_rsets() {
2454   PrintRSetsClosure cl("Printing CSet RSets");
2455   collection_set_iterate(&cl);
2456 }
2457 
2458 void G1CollectedHeap::print_all_rsets() {
2459   PrintRSetsClosure cl("Printing All RSets");;
2460   heap_region_iterate(&cl);
2461 }
2462 #endif // PRODUCT
2463 
2464 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2465 
2466   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2467   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2468   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2469 
2470   size_t eden_capacity_bytes =
2471     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2472 
2473   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2474   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2475                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2476 }
2477 
2478 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2479   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2480                        stats->unused(), stats->used(), stats->region_end_waste(),
2481                        stats->regions_filled(), stats->direct_allocated(),
2482                        stats->failure_used(), stats->failure_waste());
2483 }
2484 
2485 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2486   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2487   gc_tracer->report_gc_heap_summary(when, heap_summary);
2488 
2489   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2490   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2491 }
2492 
2493 G1CollectedHeap* G1CollectedHeap::heap() {
2494   CollectedHeap* heap = Universe::heap();
2495   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2496   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2497   return (G1CollectedHeap*)heap;
2498 }
2499 
2500 void G1CollectedHeap::gc_prologue(bool full) {
2501   // always_do_update_barrier = false;
2502   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2503 
2504   // This summary needs to be printed before incrementing total collections.
2505   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2506 
2507   // Update common counters.
2508   increment_total_collections(full /* full gc */);
2509   if (full) {
2510     increment_old_marking_cycles_started();
2511     reset_gc_time_stamp();
2512   } else {
2513     increment_gc_time_stamp();
2514   }
2515 
2516   // Fill TLAB's and such
2517   double start = os::elapsedTime();
2518   accumulate_statistics_all_tlabs();
2519   ensure_parsability(true);
2520   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2521 }
2522 
2523 void G1CollectedHeap::gc_epilogue(bool full) {
2524   // Update common counters.
2525   if (full) {
2526     // Update the number of full collections that have been completed.
2527     increment_old_marking_cycles_completed(false /* concurrent */);
2528   }
2529 
2530   // We are at the end of the GC. Total collections has already been increased.
2531   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2532 
2533   // FIXME: what is this about?
2534   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2535   // is set.
2536 #if COMPILER2_OR_JVMCI
2537   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2538 #endif
2539   // always_do_update_barrier = true;
2540 
2541   double start = os::elapsedTime();
2542   resize_all_tlabs();
2543   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2544 
2545   allocation_context_stats().update(full);
2546 
2547   MemoryService::track_memory_usage();
2548   // We have just completed a GC. Update the soft reference
2549   // policy with the new heap occupancy
2550   Universe::update_heap_info_at_gc();
2551 }
2552 
2553 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2554                                                uint gc_count_before,
2555                                                bool* succeeded,
2556                                                GCCause::Cause gc_cause) {
2557   assert_heap_not_locked_and_not_at_safepoint();
2558   VM_G1CollectForAllocation op(word_size,
2559                                gc_count_before,
2560                                gc_cause,
2561                                false, /* should_initiate_conc_mark */
2562                                g1_policy()->max_pause_time_ms(),
2563                                AllocationContext::current());
2564   VMThread::execute(&op);
2565 
2566   HeapWord* result = op.result();
2567   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2568   assert(result == NULL || ret_succeeded,
2569          "the result should be NULL if the VM did not succeed");
2570   *succeeded = ret_succeeded;
2571 
2572   assert_heap_not_locked();
2573   return result;
2574 }
2575 
2576 void
2577 G1CollectedHeap::doConcurrentMark() {
2578   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2579   if (!_cmThread->in_progress()) {
2580     _cmThread->set_started();
2581     CGC_lock->notify();
2582   }
2583 }
2584 
2585 size_t G1CollectedHeap::pending_card_num() {
2586   size_t extra_cards = 0;
2587   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2588     DirtyCardQueue& dcq = curr->dirty_card_queue();
2589     extra_cards += dcq.size();
2590   }
2591   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2592   size_t buffer_size = dcqs.buffer_size();
2593   size_t buffer_num = dcqs.completed_buffers_num();
2594 
2595   return buffer_size * buffer_num + extra_cards;
2596 }
2597 
2598 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2599  private:
2600   size_t _total_humongous;
2601   size_t _candidate_humongous;
2602 
2603   DirtyCardQueue _dcq;
2604 
2605   // We don't nominate objects with many remembered set entries, on
2606   // the assumption that such objects are likely still live.
2607   bool is_remset_small(HeapRegion* region) const {
2608     HeapRegionRemSet* const rset = region->rem_set();
2609     return G1EagerReclaimHumongousObjectsWithStaleRefs
2610       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2611       : rset->is_empty();
2612   }
2613 
2614   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2615     assert(region->is_starts_humongous(), "Must start a humongous object");
2616 
2617     oop obj = oop(region->bottom());
2618 
2619     // Dead objects cannot be eager reclaim candidates. Due to class
2620     // unloading it is unsafe to query their classes so we return early.
2621     if (heap->is_obj_dead(obj, region)) {
2622       return false;
2623     }
2624 
2625     // Candidate selection must satisfy the following constraints
2626     // while concurrent marking is in progress:
2627     //
2628     // * In order to maintain SATB invariants, an object must not be
2629     // reclaimed if it was allocated before the start of marking and
2630     // has not had its references scanned.  Such an object must have
2631     // its references (including type metadata) scanned to ensure no
2632     // live objects are missed by the marking process.  Objects
2633     // allocated after the start of concurrent marking don't need to
2634     // be scanned.
2635     //
2636     // * An object must not be reclaimed if it is on the concurrent
2637     // mark stack.  Objects allocated after the start of concurrent
2638     // marking are never pushed on the mark stack.
2639     //
2640     // Nominating only objects allocated after the start of concurrent
2641     // marking is sufficient to meet both constraints.  This may miss
2642     // some objects that satisfy the constraints, but the marking data
2643     // structures don't support efficiently performing the needed
2644     // additional tests or scrubbing of the mark stack.
2645     //
2646     // However, we presently only nominate is_typeArray() objects.
2647     // A humongous object containing references induces remembered
2648     // set entries on other regions.  In order to reclaim such an
2649     // object, those remembered sets would need to be cleaned up.
2650     //
2651     // We also treat is_typeArray() objects specially, allowing them
2652     // to be reclaimed even if allocated before the start of
2653     // concurrent mark.  For this we rely on mark stack insertion to
2654     // exclude is_typeArray() objects, preventing reclaiming an object
2655     // that is in the mark stack.  We also rely on the metadata for
2656     // such objects to be built-in and so ensured to be kept live.
2657     // Frequent allocation and drop of large binary blobs is an
2658     // important use case for eager reclaim, and this special handling
2659     // may reduce needed headroom.
2660 
2661     return obj->is_typeArray() && is_remset_small(region);
2662   }
2663 
2664  public:
2665   RegisterHumongousWithInCSetFastTestClosure()
2666   : _total_humongous(0),
2667     _candidate_humongous(0),
2668     _dcq(&JavaThread::dirty_card_queue_set()) {
2669   }
2670 
2671   virtual bool do_heap_region(HeapRegion* r) {
2672     if (!r->is_starts_humongous()) {
2673       return false;
2674     }
2675     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2676 
2677     bool is_candidate = humongous_region_is_candidate(g1h, r);
2678     uint rindex = r->hrm_index();
2679     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2680     if (is_candidate) {
2681       _candidate_humongous++;
2682       g1h->register_humongous_region_with_cset(rindex);
2683       // Is_candidate already filters out humongous object with large remembered sets.
2684       // If we have a humongous object with a few remembered sets, we simply flush these
2685       // remembered set entries into the DCQS. That will result in automatic
2686       // re-evaluation of their remembered set entries during the following evacuation
2687       // phase.
2688       if (!r->rem_set()->is_empty()) {
2689         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2690                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2691         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2692         HeapRegionRemSetIterator hrrs(r->rem_set());
2693         size_t card_index;
2694         while (hrrs.has_next(card_index)) {
2695           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2696           // The remembered set might contain references to already freed
2697           // regions. Filter out such entries to avoid failing card table
2698           // verification.
2699           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2700             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2701               *card_ptr = CardTableModRefBS::dirty_card_val();
2702               _dcq.enqueue(card_ptr);
2703             }
2704           }
2705         }
2706         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2707                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2708                hrrs.n_yielded(), r->rem_set()->occupied());
2709         r->rem_set()->clear_locked();
2710       }
2711       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2712     }
2713     _total_humongous++;
2714 
2715     return false;
2716   }
2717 
2718   size_t total_humongous() const { return _total_humongous; }
2719   size_t candidate_humongous() const { return _candidate_humongous; }
2720 
2721   void flush_rem_set_entries() { _dcq.flush(); }
2722 };
2723 
2724 void G1CollectedHeap::register_humongous_regions_with_cset() {
2725   if (!G1EagerReclaimHumongousObjects) {
2726     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2727     return;
2728   }
2729   double time = os::elapsed_counter();
2730 
2731   // Collect reclaim candidate information and register candidates with cset.
2732   RegisterHumongousWithInCSetFastTestClosure cl;
2733   heap_region_iterate(&cl);
2734 
2735   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2736   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2737                                                                   cl.total_humongous(),
2738                                                                   cl.candidate_humongous());
2739   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2740 
2741   // Finally flush all remembered set entries to re-check into the global DCQS.
2742   cl.flush_rem_set_entries();
2743 }
2744 
2745 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2746   public:
2747     bool do_heap_region(HeapRegion* hr) {
2748       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2749         hr->verify_rem_set();
2750       }
2751       return false;
2752     }
2753 };
2754 
2755 uint G1CollectedHeap::num_task_queues() const {
2756   return _task_queues->size();
2757 }
2758 
2759 #if TASKQUEUE_STATS
2760 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2761   st->print_raw_cr("GC Task Stats");
2762   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2763   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2764 }
2765 
2766 void G1CollectedHeap::print_taskqueue_stats() const {
2767   if (!log_is_enabled(Trace, gc, task, stats)) {
2768     return;
2769   }
2770   Log(gc, task, stats) log;
2771   ResourceMark rm;
2772   LogStream ls(log.trace());
2773   outputStream* st = &ls;
2774 
2775   print_taskqueue_stats_hdr(st);
2776 
2777   TaskQueueStats totals;
2778   const uint n = num_task_queues();
2779   for (uint i = 0; i < n; ++i) {
2780     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2781     totals += task_queue(i)->stats;
2782   }
2783   st->print_raw("tot "); totals.print(st); st->cr();
2784 
2785   DEBUG_ONLY(totals.verify());
2786 }
2787 
2788 void G1CollectedHeap::reset_taskqueue_stats() {
2789   const uint n = num_task_queues();
2790   for (uint i = 0; i < n; ++i) {
2791     task_queue(i)->stats.reset();
2792   }
2793 }
2794 #endif // TASKQUEUE_STATS
2795 
2796 void G1CollectedHeap::wait_for_root_region_scanning() {
2797   double scan_wait_start = os::elapsedTime();
2798   // We have to wait until the CM threads finish scanning the
2799   // root regions as it's the only way to ensure that all the
2800   // objects on them have been correctly scanned before we start
2801   // moving them during the GC.
2802   bool waited = _cm->root_regions()->wait_until_scan_finished();
2803   double wait_time_ms = 0.0;
2804   if (waited) {
2805     double scan_wait_end = os::elapsedTime();
2806     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2807   }
2808   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2809 }
2810 
2811 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2812 private:
2813   G1HRPrinter* _hr_printer;
2814 public:
2815   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2816 
2817   virtual bool do_heap_region(HeapRegion* r) {
2818     _hr_printer->cset(r);
2819     return false;
2820   }
2821 };
2822 
2823 void G1CollectedHeap::start_new_collection_set() {
2824   collection_set()->start_incremental_building();
2825 
2826   clear_cset_fast_test();
2827 
2828   guarantee(_eden.length() == 0, "eden should have been cleared");
2829   g1_policy()->transfer_survivors_to_cset(survivor());
2830 }
2831 
2832 bool
2833 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2834   assert_at_safepoint(true /* should_be_vm_thread */);
2835   guarantee(!is_gc_active(), "collection is not reentrant");
2836 
2837   if (GCLocker::check_active_before_gc()) {
2838     return false;
2839   }
2840 
2841   _gc_timer_stw->register_gc_start();
2842 
2843   GCIdMark gc_id_mark;
2844   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2845 
2846   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2847   ResourceMark rm;
2848 
2849   g1_policy()->note_gc_start();
2850 
2851   wait_for_root_region_scanning();
2852 
2853   print_heap_before_gc();
2854   print_heap_regions();
2855   trace_heap_before_gc(_gc_tracer_stw);
2856 
2857   _verifier->verify_region_sets_optional();
2858   _verifier->verify_dirty_young_regions();
2859 
2860   // We should not be doing initial mark unless the conc mark thread is running
2861   if (!_cmThread->should_terminate()) {
2862     // This call will decide whether this pause is an initial-mark
2863     // pause. If it is, during_initial_mark_pause() will return true
2864     // for the duration of this pause.
2865     g1_policy()->decide_on_conc_mark_initiation();
2866   }
2867 
2868   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2869   assert(!collector_state()->during_initial_mark_pause() ||
2870           collector_state()->gcs_are_young(), "sanity");
2871 
2872   // We also do not allow mixed GCs during marking.
2873   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2874 
2875   // Record whether this pause is an initial mark. When the current
2876   // thread has completed its logging output and it's safe to signal
2877   // the CM thread, the flag's value in the policy has been reset.
2878   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2879 
2880   // Inner scope for scope based logging, timers, and stats collection
2881   {
2882     EvacuationInfo evacuation_info;
2883 
2884     if (collector_state()->during_initial_mark_pause()) {
2885       // We are about to start a marking cycle, so we increment the
2886       // full collection counter.
2887       increment_old_marking_cycles_started();
2888       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2889     }
2890 
2891     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2892 
2893     GCTraceCPUTime tcpu;
2894 
2895     G1HeapVerifier::G1VerifyType verify_type;
2896     FormatBuffer<> gc_string("Pause ");
2897     if (collector_state()->during_initial_mark_pause()) {
2898       gc_string.append("Initial Mark");
2899       verify_type = G1HeapVerifier::G1VerifyInitialMark;
2900     } else if (collector_state()->gcs_are_young()) {
2901       gc_string.append("Young");
2902       verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2903     } else {
2904       gc_string.append("Mixed");
2905       verify_type = G1HeapVerifier::G1VerifyMixed;
2906     }
2907     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2908 
2909     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2910                                                                   workers()->active_workers(),
2911                                                                   Threads::number_of_non_daemon_threads());
2912     workers()->update_active_workers(active_workers);
2913     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2914 
2915     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2916     TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2917 
2918     // If the secondary_free_list is not empty, append it to the
2919     // free_list. No need to wait for the cleanup operation to finish;
2920     // the region allocation code will check the secondary_free_list
2921     // and wait if necessary. If the G1StressConcRegionFreeing flag is
2922     // set, skip this step so that the region allocation code has to
2923     // get entries from the secondary_free_list.
2924     if (!G1StressConcRegionFreeing) {
2925       append_secondary_free_list_if_not_empty_with_lock();
2926     }
2927 
2928     G1HeapTransition heap_transition(this);
2929     size_t heap_used_bytes_before_gc = used();
2930 
2931     // Don't dynamically change the number of GC threads this early.  A value of
2932     // 0 is used to indicate serial work.  When parallel work is done,
2933     // it will be set.
2934 
2935     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2936       IsGCActiveMark x;
2937 
2938       gc_prologue(false);
2939 
2940       if (VerifyRememberedSets) {
2941         log_info(gc, verify)("[Verifying RemSets before GC]");
2942         VerifyRegionRemSetClosure v_cl;
2943         heap_region_iterate(&v_cl);
2944       }
2945 
2946       _verifier->verify_before_gc(verify_type);
2947 
2948       _verifier->check_bitmaps("GC Start");
2949 
2950 #if COMPILER2_OR_JVMCI
2951       DerivedPointerTable::clear();
2952 #endif
2953 
2954       // Please see comment in g1CollectedHeap.hpp and
2955       // G1CollectedHeap::ref_processing_init() to see how
2956       // reference processing currently works in G1.
2957 
2958       // Enable discovery in the STW reference processor
2959       if (g1_policy()->should_process_references()) {
2960         ref_processor_stw()->enable_discovery();
2961       } else {
2962         ref_processor_stw()->disable_discovery();
2963       }
2964 
2965       {
2966         // We want to temporarily turn off discovery by the
2967         // CM ref processor, if necessary, and turn it back on
2968         // on again later if we do. Using a scoped
2969         // NoRefDiscovery object will do this.
2970         NoRefDiscovery no_cm_discovery(ref_processor_cm());
2971 
2972         // Forget the current alloc region (we might even choose it to be part
2973         // of the collection set!).
2974         _allocator->release_mutator_alloc_region();
2975 
2976         // This timing is only used by the ergonomics to handle our pause target.
2977         // It is unclear why this should not include the full pause. We will
2978         // investigate this in CR 7178365.
2979         //
2980         // Preserving the old comment here if that helps the investigation:
2981         //
2982         // The elapsed time induced by the start time below deliberately elides
2983         // the possible verification above.
2984         double sample_start_time_sec = os::elapsedTime();
2985 
2986         g1_policy()->record_collection_pause_start(sample_start_time_sec);
2987 
2988         if (collector_state()->during_initial_mark_pause()) {
2989           concurrent_mark()->checkpoint_roots_initial_pre();
2990         }
2991 
2992         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2993 
2994         evacuation_info.set_collectionset_regions(collection_set()->region_length());
2995 
2996         // Make sure the remembered sets are up to date. This needs to be
2997         // done before register_humongous_regions_with_cset(), because the
2998         // remembered sets are used there to choose eager reclaim candidates.
2999         // If the remembered sets are not up to date we might miss some
3000         // entries that need to be handled.
3001         g1_rem_set()->cleanupHRRS();
3002 
3003         register_humongous_regions_with_cset();
3004 
3005         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3006 
3007         // We call this after finalize_cset() to
3008         // ensure that the CSet has been finalized.
3009         _cm->verify_no_cset_oops();
3010 
3011         if (_hr_printer.is_active()) {
3012           G1PrintCollectionSetClosure cl(&_hr_printer);
3013           _collection_set.iterate(&cl);
3014         }
3015 
3016         // Initialize the GC alloc regions.
3017         _allocator->init_gc_alloc_regions(evacuation_info);
3018 
3019         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3020         pre_evacuate_collection_set();
3021 
3022         // Actually do the work...
3023         evacuate_collection_set(evacuation_info, &per_thread_states);
3024 
3025         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3026 
3027         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3028         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3029 
3030         eagerly_reclaim_humongous_regions();
3031 
3032         record_obj_copy_mem_stats();
3033         _survivor_evac_stats.adjust_desired_plab_sz();
3034         _old_evac_stats.adjust_desired_plab_sz();
3035 
3036         double start = os::elapsedTime();
3037         start_new_collection_set();
3038         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3039 
3040         if (evacuation_failed()) {
3041           set_used(recalculate_used());
3042           if (_archive_allocator != NULL) {
3043             _archive_allocator->clear_used();
3044           }
3045           for (uint i = 0; i < ParallelGCThreads; i++) {
3046             if (_evacuation_failed_info_array[i].has_failed()) {
3047               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3048             }
3049           }
3050         } else {
3051           // The "used" of the the collection set have already been subtracted
3052           // when they were freed.  Add in the bytes evacuated.
3053           increase_used(g1_policy()->bytes_copied_during_gc());
3054         }
3055 
3056         if (collector_state()->during_initial_mark_pause()) {
3057           // We have to do this before we notify the CM threads that
3058           // they can start working to make sure that all the
3059           // appropriate initialization is done on the CM object.
3060           concurrent_mark()->checkpoint_roots_initial_post();
3061           collector_state()->set_mark_in_progress(true);
3062           // Note that we don't actually trigger the CM thread at
3063           // this point. We do that later when we're sure that
3064           // the current thread has completed its logging output.
3065         }
3066 
3067         allocate_dummy_regions();
3068 
3069         _allocator->init_mutator_alloc_region();
3070 
3071         {
3072           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3073           if (expand_bytes > 0) {
3074             size_t bytes_before = capacity();
3075             // No need for an ergo logging here,
3076             // expansion_amount() does this when it returns a value > 0.
3077             double expand_ms;
3078             if (!expand(expand_bytes, _workers, &expand_ms)) {
3079               // We failed to expand the heap. Cannot do anything about it.
3080             }
3081             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3082           }
3083         }
3084 
3085         // We redo the verification but now wrt to the new CSet which
3086         // has just got initialized after the previous CSet was freed.
3087         _cm->verify_no_cset_oops();
3088 
3089         // This timing is only used by the ergonomics to handle our pause target.
3090         // It is unclear why this should not include the full pause. We will
3091         // investigate this in CR 7178365.
3092         double sample_end_time_sec = os::elapsedTime();
3093         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3094         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3095         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3096 
3097         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3098         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3099 
3100         if (VerifyRememberedSets) {
3101           log_info(gc, verify)("[Verifying RemSets after GC]");
3102           VerifyRegionRemSetClosure v_cl;
3103           heap_region_iterate(&v_cl);
3104         }
3105 
3106         _verifier->verify_after_gc(verify_type);
3107         _verifier->check_bitmaps("GC End");
3108 
3109         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3110         ref_processor_stw()->verify_no_references_recorded();
3111 
3112         // CM reference discovery will be re-enabled if necessary.
3113       }
3114 
3115 #ifdef TRACESPINNING
3116       ParallelTaskTerminator::print_termination_counts();
3117 #endif
3118 
3119       gc_epilogue(false);
3120     }
3121 
3122     // Print the remainder of the GC log output.
3123     if (evacuation_failed()) {
3124       log_info(gc)("To-space exhausted");
3125     }
3126 
3127     g1_policy()->print_phases();
3128     heap_transition.print();
3129 
3130     // It is not yet to safe to tell the concurrent mark to
3131     // start as we have some optional output below. We don't want the
3132     // output from the concurrent mark thread interfering with this
3133     // logging output either.
3134 
3135     _hrm.verify_optional();
3136     _verifier->verify_region_sets_optional();
3137 
3138     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3139     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3140 
3141     print_heap_after_gc();
3142     print_heap_regions();
3143     trace_heap_after_gc(_gc_tracer_stw);
3144 
3145     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3146     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3147     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3148     // before any GC notifications are raised.
3149     g1mm()->update_sizes();
3150 
3151     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3152     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3153     _gc_timer_stw->register_gc_end();
3154     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3155   }
3156   // It should now be safe to tell the concurrent mark thread to start
3157   // without its logging output interfering with the logging output
3158   // that came from the pause.
3159 
3160   if (should_start_conc_mark) {
3161     // CAUTION: after the doConcurrentMark() call below,
3162     // the concurrent marking thread(s) could be running
3163     // concurrently with us. Make sure that anything after
3164     // this point does not assume that we are the only GC thread
3165     // running. Note: of course, the actual marking work will
3166     // not start until the safepoint itself is released in
3167     // SuspendibleThreadSet::desynchronize().
3168     doConcurrentMark();
3169   }
3170 
3171   return true;
3172 }
3173 
3174 void G1CollectedHeap::remove_self_forwarding_pointers() {
3175   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3176   workers()->run_task(&rsfp_task);
3177 }
3178 
3179 void G1CollectedHeap::restore_after_evac_failure() {
3180   double remove_self_forwards_start = os::elapsedTime();
3181 
3182   remove_self_forwarding_pointers();
3183   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3184   _preserved_marks_set.restore(&task_executor);
3185 
3186   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3187 }
3188 
3189 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3190   if (!_evacuation_failed) {
3191     _evacuation_failed = true;
3192   }
3193 
3194   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3195   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3196 }
3197 
3198 bool G1ParEvacuateFollowersClosure::offer_termination() {
3199   G1ParScanThreadState* const pss = par_scan_state();
3200   start_term_time();
3201   const bool res = terminator()->offer_termination();
3202   end_term_time();
3203   return res;
3204 }
3205 
3206 void G1ParEvacuateFollowersClosure::do_void() {
3207   G1ParScanThreadState* const pss = par_scan_state();
3208   pss->trim_queue();
3209   do {
3210     pss->steal_and_trim_queue(queues());
3211   } while (!offer_termination());
3212 }
3213 
3214 class G1ParTask : public AbstractGangTask {
3215 protected:
3216   G1CollectedHeap*         _g1h;
3217   G1ParScanThreadStateSet* _pss;
3218   RefToScanQueueSet*       _queues;
3219   G1RootProcessor*         _root_processor;
3220   ParallelTaskTerminator   _terminator;
3221   uint                     _n_workers;
3222 
3223 public:
3224   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3225     : AbstractGangTask("G1 collection"),
3226       _g1h(g1h),
3227       _pss(per_thread_states),
3228       _queues(task_queues),
3229       _root_processor(root_processor),
3230       _terminator(n_workers, _queues),
3231       _n_workers(n_workers)
3232   {}
3233 
3234   void work(uint worker_id) {
3235     if (worker_id >= _n_workers) return;  // no work needed this round
3236 
3237     double start_sec = os::elapsedTime();
3238     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3239 
3240     {
3241       ResourceMark rm;
3242       HandleMark   hm;
3243 
3244       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3245 
3246       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3247       pss->set_ref_processor(rp);
3248 
3249       double start_strong_roots_sec = os::elapsedTime();
3250 
3251       _root_processor->evacuate_roots(pss->closures(), worker_id);
3252 
3253       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3254       // treating the nmethods visited to act as roots for concurrent marking.
3255       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3256       // objects copied by the current evacuation.
3257       _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3258                                                       pss->closures()->weak_codeblobs(),
3259                                                       worker_id);
3260 
3261       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3262 
3263       double term_sec = 0.0;
3264       size_t evac_term_attempts = 0;
3265       {
3266         double start = os::elapsedTime();
3267         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3268         evac.do_void();
3269 
3270         evac_term_attempts = evac.term_attempts();
3271         term_sec = evac.term_time();
3272         double elapsed_sec = os::elapsedTime() - start;
3273         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3274         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3275         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3276       }
3277 
3278       assert(pss->queue_is_empty(), "should be empty");
3279 
3280       if (log_is_enabled(Debug, gc, task, stats)) {
3281         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3282         size_t lab_waste;
3283         size_t lab_undo_waste;
3284         pss->waste(lab_waste, lab_undo_waste);
3285         _g1h->print_termination_stats(worker_id,
3286                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3287                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3288                                       term_sec * 1000.0,                          /* evac term time */
3289                                       evac_term_attempts,                         /* evac term attempts */
3290                                       lab_waste,                                  /* alloc buffer waste */
3291                                       lab_undo_waste                              /* undo waste */
3292                                       );
3293       }
3294 
3295       // Close the inner scope so that the ResourceMark and HandleMark
3296       // destructors are executed here and are included as part of the
3297       // "GC Worker Time".
3298     }
3299     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3300   }
3301 };
3302 
3303 void G1CollectedHeap::print_termination_stats_hdr() {
3304   log_debug(gc, task, stats)("GC Termination Stats");
3305   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3306   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3307   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3308 }
3309 
3310 void G1CollectedHeap::print_termination_stats(uint worker_id,
3311                                               double elapsed_ms,
3312                                               double strong_roots_ms,
3313                                               double term_ms,
3314                                               size_t term_attempts,
3315                                               size_t alloc_buffer_waste,
3316                                               size_t undo_waste) const {
3317   log_debug(gc, task, stats)
3318               ("%3d %9.2f %9.2f %6.2f "
3319                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3320                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3321                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3322                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3323                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3324                alloc_buffer_waste * HeapWordSize / K,
3325                undo_waste * HeapWordSize / K);
3326 }
3327 
3328 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3329 private:
3330   BoolObjectClosure* _is_alive;
3331   G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3332 
3333   int _initial_string_table_size;
3334   int _initial_symbol_table_size;
3335 
3336   bool  _process_strings;
3337   int _strings_processed;
3338   int _strings_removed;
3339 
3340   bool  _process_symbols;
3341   int _symbols_processed;
3342   int _symbols_removed;
3343 
3344   bool _process_string_dedup;
3345 
3346 public:
3347   G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3348     AbstractGangTask("String/Symbol Unlinking"),
3349     _is_alive(is_alive),
3350     _dedup_closure(is_alive, NULL, false),
3351     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3352     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3353     _process_string_dedup(process_string_dedup) {
3354 
3355     _initial_string_table_size = StringTable::the_table()->table_size();
3356     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3357     if (process_strings) {
3358       StringTable::clear_parallel_claimed_index();
3359     }
3360     if (process_symbols) {
3361       SymbolTable::clear_parallel_claimed_index();
3362     }
3363   }
3364 
3365   ~G1StringAndSymbolCleaningTask() {
3366     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3367               "claim value %d after unlink less than initial string table size %d",
3368               StringTable::parallel_claimed_index(), _initial_string_table_size);
3369     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3370               "claim value %d after unlink less than initial symbol table size %d",
3371               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3372 
3373     log_info(gc, stringtable)(
3374         "Cleaned string and symbol table, "
3375         "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3376         "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3377         strings_processed(), strings_removed(),
3378         symbols_processed(), symbols_removed());
3379   }
3380 
3381   void work(uint worker_id) {
3382     int strings_processed = 0;
3383     int strings_removed = 0;
3384     int symbols_processed = 0;
3385     int symbols_removed = 0;
3386     if (_process_strings) {
3387       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3388       Atomic::add(strings_processed, &_strings_processed);
3389       Atomic::add(strings_removed, &_strings_removed);
3390     }
3391     if (_process_symbols) {
3392       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3393       Atomic::add(symbols_processed, &_symbols_processed);
3394       Atomic::add(symbols_removed, &_symbols_removed);
3395     }
3396     if (_process_string_dedup) {
3397       G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3398     }
3399   }
3400 
3401   size_t strings_processed() const { return (size_t)_strings_processed; }
3402   size_t strings_removed()   const { return (size_t)_strings_removed; }
3403 
3404   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3405   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3406 };
3407 
3408 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3409 private:
3410   static Monitor* _lock;
3411 
3412   BoolObjectClosure* const _is_alive;
3413   const bool               _unloading_occurred;
3414   const uint               _num_workers;
3415 
3416   // Variables used to claim nmethods.
3417   CompiledMethod* _first_nmethod;
3418   CompiledMethod* volatile _claimed_nmethod;
3419 
3420   // The list of nmethods that need to be processed by the second pass.
3421   CompiledMethod* volatile _postponed_list;
3422   volatile uint            _num_entered_barrier;
3423 
3424  public:
3425   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3426       _is_alive(is_alive),
3427       _unloading_occurred(unloading_occurred),
3428       _num_workers(num_workers),
3429       _first_nmethod(NULL),
3430       _claimed_nmethod(NULL),
3431       _postponed_list(NULL),
3432       _num_entered_barrier(0)
3433   {
3434     CompiledMethod::increase_unloading_clock();
3435     // Get first alive nmethod
3436     CompiledMethodIterator iter = CompiledMethodIterator();
3437     if(iter.next_alive()) {
3438       _first_nmethod = iter.method();
3439     }
3440     _claimed_nmethod = _first_nmethod;
3441   }
3442 
3443   ~G1CodeCacheUnloadingTask() {
3444     CodeCache::verify_clean_inline_caches();
3445 
3446     CodeCache::set_needs_cache_clean(false);
3447     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3448 
3449     CodeCache::verify_icholder_relocations();
3450   }
3451 
3452  private:
3453   void add_to_postponed_list(CompiledMethod* nm) {
3454       CompiledMethod* old;
3455       do {
3456         old = _postponed_list;
3457         nm->set_unloading_next(old);
3458       } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3459   }
3460 
3461   void clean_nmethod(CompiledMethod* nm) {
3462     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3463 
3464     if (postponed) {
3465       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3466       add_to_postponed_list(nm);
3467     }
3468 
3469     // Mark that this thread has been cleaned/unloaded.
3470     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3471     nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3472   }
3473 
3474   void clean_nmethod_postponed(CompiledMethod* nm) {
3475     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3476   }
3477 
3478   static const int MaxClaimNmethods = 16;
3479 
3480   void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3481     CompiledMethod* first;
3482     CompiledMethodIterator last;
3483 
3484     do {
3485       *num_claimed_nmethods = 0;
3486 
3487       first = _claimed_nmethod;
3488       last = CompiledMethodIterator(first);
3489 
3490       if (first != NULL) {
3491 
3492         for (int i = 0; i < MaxClaimNmethods; i++) {
3493           if (!last.next_alive()) {
3494             break;
3495           }
3496           claimed_nmethods[i] = last.method();
3497           (*num_claimed_nmethods)++;
3498         }
3499       }
3500 
3501     } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3502   }
3503 
3504   CompiledMethod* claim_postponed_nmethod() {
3505     CompiledMethod* claim;
3506     CompiledMethod* next;
3507 
3508     do {
3509       claim = _postponed_list;
3510       if (claim == NULL) {
3511         return NULL;
3512       }
3513 
3514       next = claim->unloading_next();
3515 
3516     } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3517 
3518     return claim;
3519   }
3520 
3521  public:
3522   // Mark that we're done with the first pass of nmethod cleaning.
3523   void barrier_mark(uint worker_id) {
3524     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3525     _num_entered_barrier++;
3526     if (_num_entered_barrier == _num_workers) {
3527       ml.notify_all();
3528     }
3529   }
3530 
3531   // See if we have to wait for the other workers to
3532   // finish their first-pass nmethod cleaning work.
3533   void barrier_wait(uint worker_id) {
3534     if (_num_entered_barrier < _num_workers) {
3535       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3536       while (_num_entered_barrier < _num_workers) {
3537           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3538       }
3539     }
3540   }
3541 
3542   // Cleaning and unloading of nmethods. Some work has to be postponed
3543   // to the second pass, when we know which nmethods survive.
3544   void work_first_pass(uint worker_id) {
3545     // The first nmethods is claimed by the first worker.
3546     if (worker_id == 0 && _first_nmethod != NULL) {
3547       clean_nmethod(_first_nmethod);
3548       _first_nmethod = NULL;
3549     }
3550 
3551     int num_claimed_nmethods;
3552     CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3553 
3554     while (true) {
3555       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3556 
3557       if (num_claimed_nmethods == 0) {
3558         break;
3559       }
3560 
3561       for (int i = 0; i < num_claimed_nmethods; i++) {
3562         clean_nmethod(claimed_nmethods[i]);
3563       }
3564     }
3565   }
3566 
3567   void work_second_pass(uint worker_id) {
3568     CompiledMethod* nm;
3569     // Take care of postponed nmethods.
3570     while ((nm = claim_postponed_nmethod()) != NULL) {
3571       clean_nmethod_postponed(nm);
3572     }
3573   }
3574 };
3575 
3576 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3577 
3578 class G1KlassCleaningTask : public StackObj {
3579   BoolObjectClosure*                      _is_alive;
3580   volatile int                            _clean_klass_tree_claimed;
3581   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3582 
3583  public:
3584   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3585       _is_alive(is_alive),
3586       _clean_klass_tree_claimed(0),
3587       _klass_iterator() {
3588   }
3589 
3590  private:
3591   bool claim_clean_klass_tree_task() {
3592     if (_clean_klass_tree_claimed) {
3593       return false;
3594     }
3595 
3596     return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3597   }
3598 
3599   InstanceKlass* claim_next_klass() {
3600     Klass* klass;
3601     do {
3602       klass =_klass_iterator.next_klass();
3603     } while (klass != NULL && !klass->is_instance_klass());
3604 
3605     // this can be null so don't call InstanceKlass::cast
3606     return static_cast<InstanceKlass*>(klass);
3607   }
3608 
3609 public:
3610 
3611   void clean_klass(InstanceKlass* ik) {
3612     ik->clean_weak_instanceklass_links(_is_alive);
3613   }
3614 
3615   void work() {
3616     ResourceMark rm;
3617 
3618     // One worker will clean the subklass/sibling klass tree.
3619     if (claim_clean_klass_tree_task()) {
3620       Klass::clean_subklass_tree(_is_alive);
3621     }
3622 
3623     // All workers will help cleaning the classes,
3624     InstanceKlass* klass;
3625     while ((klass = claim_next_klass()) != NULL) {
3626       clean_klass(klass);
3627     }
3628   }
3629 };
3630 
3631 class G1ResolvedMethodCleaningTask : public StackObj {
3632   BoolObjectClosure* _is_alive;
3633   volatile int       _resolved_method_task_claimed;
3634 public:
3635   G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3636       _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3637 
3638   bool claim_resolved_method_task() {
3639     if (_resolved_method_task_claimed) {
3640       return false;
3641     }
3642     return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3643   }
3644 
3645   // These aren't big, one thread can do it all.
3646   void work() {
3647     if (claim_resolved_method_task()) {
3648       ResolvedMethodTable::unlink(_is_alive);
3649     }
3650   }
3651 };
3652 
3653 
3654 // To minimize the remark pause times, the tasks below are done in parallel.
3655 class G1ParallelCleaningTask : public AbstractGangTask {
3656 private:
3657   G1StringAndSymbolCleaningTask _string_symbol_task;
3658   G1CodeCacheUnloadingTask      _code_cache_task;
3659   G1KlassCleaningTask           _klass_cleaning_task;
3660   G1ResolvedMethodCleaningTask  _resolved_method_cleaning_task;
3661 
3662 public:
3663   // The constructor is run in the VMThread.
3664   G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3665       AbstractGangTask("Parallel Cleaning"),
3666       _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3667       _code_cache_task(num_workers, is_alive, unloading_occurred),
3668       _klass_cleaning_task(is_alive),
3669       _resolved_method_cleaning_task(is_alive) {
3670   }
3671 
3672   // The parallel work done by all worker threads.
3673   void work(uint worker_id) {
3674     // Do first pass of code cache cleaning.
3675     _code_cache_task.work_first_pass(worker_id);
3676 
3677     // Let the threads mark that the first pass is done.
3678     _code_cache_task.barrier_mark(worker_id);
3679 
3680     // Clean the Strings and Symbols.
3681     _string_symbol_task.work(worker_id);
3682 
3683     // Clean unreferenced things in the ResolvedMethodTable
3684     _resolved_method_cleaning_task.work();
3685 
3686     // Wait for all workers to finish the first code cache cleaning pass.
3687     _code_cache_task.barrier_wait(worker_id);
3688 
3689     // Do the second code cache cleaning work, which realize on
3690     // the liveness information gathered during the first pass.
3691     _code_cache_task.work_second_pass(worker_id);
3692 
3693     // Clean all klasses that were not unloaded.
3694     _klass_cleaning_task.work();
3695   }
3696 };
3697 
3698 
3699 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3700                                         bool class_unloading_occurred) {
3701   uint n_workers = workers()->active_workers();
3702 
3703   G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3704   workers()->run_task(&g1_unlink_task);
3705 }
3706 
3707 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3708                                        bool process_strings,
3709                                        bool process_symbols,
3710                                        bool process_string_dedup) {
3711   if (!process_strings && !process_symbols && !process_string_dedup) {
3712     // Nothing to clean.
3713     return;
3714   }
3715 
3716   G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3717   workers()->run_task(&g1_unlink_task);
3718 
3719 }
3720 
3721 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3722  private:
3723   DirtyCardQueueSet* _queue;
3724   G1CollectedHeap* _g1h;
3725  public:
3726   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3727     _queue(queue), _g1h(g1h) { }
3728 
3729   virtual void work(uint worker_id) {
3730     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3731     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3732 
3733     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3734     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3735 
3736     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3737   }
3738 };
3739 
3740 void G1CollectedHeap::redirty_logged_cards() {
3741   double redirty_logged_cards_start = os::elapsedTime();
3742 
3743   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3744   dirty_card_queue_set().reset_for_par_iteration();
3745   workers()->run_task(&redirty_task);
3746 
3747   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3748   dcq.merge_bufferlists(&dirty_card_queue_set());
3749   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3750 
3751   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3752 }
3753 
3754 // Weak Reference Processing support
3755 
3756 // An always "is_alive" closure that is used to preserve referents.
3757 // If the object is non-null then it's alive.  Used in the preservation
3758 // of referent objects that are pointed to by reference objects
3759 // discovered by the CM ref processor.
3760 class G1AlwaysAliveClosure: public BoolObjectClosure {
3761   G1CollectedHeap* _g1;
3762 public:
3763   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3764   bool do_object_b(oop p) {
3765     if (p != NULL) {
3766       return true;
3767     }
3768     return false;
3769   }
3770 };
3771 
3772 bool G1STWIsAliveClosure::do_object_b(oop p) {
3773   // An object is reachable if it is outside the collection set,
3774   // or is inside and copied.
3775   return !_g1->is_in_cset(p) || p->is_forwarded();
3776 }
3777 
3778 // Non Copying Keep Alive closure
3779 class G1KeepAliveClosure: public OopClosure {
3780   G1CollectedHeap* _g1;
3781 public:
3782   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3783   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3784   void do_oop(oop* p) {
3785     oop obj = *p;
3786     assert(obj != NULL, "the caller should have filtered out NULL values");
3787 
3788     const InCSetState cset_state = _g1->in_cset_state(obj);
3789     if (!cset_state.is_in_cset_or_humongous()) {
3790       return;
3791     }
3792     if (cset_state.is_in_cset()) {
3793       assert( obj->is_forwarded(), "invariant" );
3794       *p = obj->forwardee();
3795     } else {
3796       assert(!obj->is_forwarded(), "invariant" );
3797       assert(cset_state.is_humongous(),
3798              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3799       _g1->set_humongous_is_live(obj);
3800     }
3801   }
3802 };
3803 
3804 // Copying Keep Alive closure - can be called from both
3805 // serial and parallel code as long as different worker
3806 // threads utilize different G1ParScanThreadState instances
3807 // and different queues.
3808 
3809 class G1CopyingKeepAliveClosure: public OopClosure {
3810   G1CollectedHeap*         _g1h;
3811   OopClosure*              _copy_non_heap_obj_cl;
3812   G1ParScanThreadState*    _par_scan_state;
3813 
3814 public:
3815   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3816                             OopClosure* non_heap_obj_cl,
3817                             G1ParScanThreadState* pss):
3818     _g1h(g1h),
3819     _copy_non_heap_obj_cl(non_heap_obj_cl),
3820     _par_scan_state(pss)
3821   {}
3822 
3823   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3824   virtual void do_oop(      oop* p) { do_oop_work(p); }
3825 
3826   template <class T> void do_oop_work(T* p) {
3827     oop obj = oopDesc::load_decode_heap_oop(p);
3828 
3829     if (_g1h->is_in_cset_or_humongous(obj)) {
3830       // If the referent object has been forwarded (either copied
3831       // to a new location or to itself in the event of an
3832       // evacuation failure) then we need to update the reference
3833       // field and, if both reference and referent are in the G1
3834       // heap, update the RSet for the referent.
3835       //
3836       // If the referent has not been forwarded then we have to keep
3837       // it alive by policy. Therefore we have copy the referent.
3838       //
3839       // If the reference field is in the G1 heap then we can push
3840       // on the PSS queue. When the queue is drained (after each
3841       // phase of reference processing) the object and it's followers
3842       // will be copied, the reference field set to point to the
3843       // new location, and the RSet updated. Otherwise we need to
3844       // use the the non-heap or metadata closures directly to copy
3845       // the referent object and update the pointer, while avoiding
3846       // updating the RSet.
3847 
3848       if (_g1h->is_in_g1_reserved(p)) {
3849         _par_scan_state->push_on_queue(p);
3850       } else {
3851         assert(!Metaspace::contains((const void*)p),
3852                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3853         _copy_non_heap_obj_cl->do_oop(p);
3854       }
3855     }
3856   }
3857 };
3858 
3859 // Serial drain queue closure. Called as the 'complete_gc'
3860 // closure for each discovered list in some of the
3861 // reference processing phases.
3862 
3863 class G1STWDrainQueueClosure: public VoidClosure {
3864 protected:
3865   G1CollectedHeap* _g1h;
3866   G1ParScanThreadState* _par_scan_state;
3867 
3868   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3869 
3870 public:
3871   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3872     _g1h(g1h),
3873     _par_scan_state(pss)
3874   { }
3875 
3876   void do_void() {
3877     G1ParScanThreadState* const pss = par_scan_state();
3878     pss->trim_queue();
3879   }
3880 };
3881 
3882 // Parallel Reference Processing closures
3883 
3884 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3885 // processing during G1 evacuation pauses.
3886 
3887 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3888 private:
3889   G1CollectedHeap*          _g1h;
3890   G1ParScanThreadStateSet*  _pss;
3891   RefToScanQueueSet*        _queues;
3892   WorkGang*                 _workers;
3893   uint                      _active_workers;
3894 
3895 public:
3896   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3897                            G1ParScanThreadStateSet* per_thread_states,
3898                            WorkGang* workers,
3899                            RefToScanQueueSet *task_queues,
3900                            uint n_workers) :
3901     _g1h(g1h),
3902     _pss(per_thread_states),
3903     _queues(task_queues),
3904     _workers(workers),
3905     _active_workers(n_workers)
3906   {
3907     g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3908   }
3909 
3910   // Executes the given task using concurrent marking worker threads.
3911   virtual void execute(ProcessTask& task);
3912   virtual void execute(EnqueueTask& task);
3913 };
3914 
3915 // Gang task for possibly parallel reference processing
3916 
3917 class G1STWRefProcTaskProxy: public AbstractGangTask {
3918   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3919   ProcessTask&     _proc_task;
3920   G1CollectedHeap* _g1h;
3921   G1ParScanThreadStateSet* _pss;
3922   RefToScanQueueSet* _task_queues;
3923   ParallelTaskTerminator* _terminator;
3924 
3925 public:
3926   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3927                         G1CollectedHeap* g1h,
3928                         G1ParScanThreadStateSet* per_thread_states,
3929                         RefToScanQueueSet *task_queues,
3930                         ParallelTaskTerminator* terminator) :
3931     AbstractGangTask("Process reference objects in parallel"),
3932     _proc_task(proc_task),
3933     _g1h(g1h),
3934     _pss(per_thread_states),
3935     _task_queues(task_queues),
3936     _terminator(terminator)
3937   {}
3938 
3939   virtual void work(uint worker_id) {
3940     // The reference processing task executed by a single worker.
3941     ResourceMark rm;
3942     HandleMark   hm;
3943 
3944     G1STWIsAliveClosure is_alive(_g1h);
3945 
3946     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
3947     pss->set_ref_processor(NULL);
3948 
3949     // Keep alive closure.
3950     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3951 
3952     // Complete GC closure
3953     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3954 
3955     // Call the reference processing task's work routine.
3956     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3957 
3958     // Note we cannot assert that the refs array is empty here as not all
3959     // of the processing tasks (specifically phase2 - pp2_work) execute
3960     // the complete_gc closure (which ordinarily would drain the queue) so
3961     // the queue may not be empty.
3962   }
3963 };
3964 
3965 // Driver routine for parallel reference processing.
3966 // Creates an instance of the ref processing gang
3967 // task and has the worker threads execute it.
3968 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3969   assert(_workers != NULL, "Need parallel worker threads.");
3970 
3971   ParallelTaskTerminator terminator(_active_workers, _queues);
3972   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3973 
3974   _workers->run_task(&proc_task_proxy);
3975 }
3976 
3977 // Gang task for parallel reference enqueueing.
3978 
3979 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
3980   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
3981   EnqueueTask& _enq_task;
3982 
3983 public:
3984   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
3985     AbstractGangTask("Enqueue reference objects in parallel"),
3986     _enq_task(enq_task)
3987   { }
3988 
3989   virtual void work(uint worker_id) {
3990     _enq_task.work(worker_id);
3991   }
3992 };
3993 
3994 // Driver routine for parallel reference enqueueing.
3995 // Creates an instance of the ref enqueueing gang
3996 // task and has the worker threads execute it.
3997 
3998 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
3999   assert(_workers != NULL, "Need parallel worker threads.");
4000 
4001   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4002 
4003   _workers->run_task(&enq_task_proxy);
4004 }
4005 
4006 // End of weak reference support closures
4007 
4008 // Abstract task used to preserve (i.e. copy) any referent objects
4009 // that are in the collection set and are pointed to by reference
4010 // objects discovered by the CM ref processor.
4011 
4012 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4013 protected:
4014   G1CollectedHeap*         _g1h;
4015   G1ParScanThreadStateSet* _pss;
4016   RefToScanQueueSet*       _queues;
4017   ParallelTaskTerminator   _terminator;
4018   uint                     _n_workers;
4019 
4020 public:
4021   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4022     AbstractGangTask("ParPreserveCMReferents"),
4023     _g1h(g1h),
4024     _pss(per_thread_states),
4025     _queues(task_queues),
4026     _terminator(workers, _queues),
4027     _n_workers(workers)
4028   {
4029     g1h->ref_processor_cm()->set_active_mt_degree(workers);
4030   }
4031 
4032   void work(uint worker_id) {
4033     G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4034 
4035     ResourceMark rm;
4036     HandleMark   hm;
4037 
4038     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4039     pss->set_ref_processor(NULL);
4040     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4041 
4042     // Is alive closure
4043     G1AlwaysAliveClosure always_alive(_g1h);
4044 
4045     // Copying keep alive closure. Applied to referent objects that need
4046     // to be copied.
4047     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4048 
4049     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4050 
4051     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4052     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4053 
4054     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4055     // So this must be true - but assert just in case someone decides to
4056     // change the worker ids.
4057     assert(worker_id < limit, "sanity");
4058     assert(!rp->discovery_is_atomic(), "check this code");
4059 
4060     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4061     for (uint idx = worker_id; idx < limit; idx += stride) {
4062       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4063 
4064       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4065       while (iter.has_next()) {
4066         // Since discovery is not atomic for the CM ref processor, we
4067         // can see some null referent objects.
4068         iter.load_ptrs(DEBUG_ONLY(true));
4069         oop ref = iter.obj();
4070 
4071         // This will filter nulls.
4072         if (iter.is_referent_alive()) {
4073           iter.make_referent_alive();
4074         }
4075         iter.move_to_next();
4076       }
4077     }
4078 
4079     // Drain the queue - which may cause stealing
4080     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4081     drain_queue.do_void();
4082     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4083     assert(pss->queue_is_empty(), "should be");
4084   }
4085 };
4086 
4087 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4088   // Any reference objects, in the collection set, that were 'discovered'
4089   // by the CM ref processor should have already been copied (either by
4090   // applying the external root copy closure to the discovered lists, or
4091   // by following an RSet entry).
4092   //
4093   // But some of the referents, that are in the collection set, that these
4094   // reference objects point to may not have been copied: the STW ref
4095   // processor would have seen that the reference object had already
4096   // been 'discovered' and would have skipped discovering the reference,
4097   // but would not have treated the reference object as a regular oop.
4098   // As a result the copy closure would not have been applied to the
4099   // referent object.
4100   //
4101   // We need to explicitly copy these referent objects - the references
4102   // will be processed at the end of remarking.
4103   //
4104   // We also need to do this copying before we process the reference
4105   // objects discovered by the STW ref processor in case one of these
4106   // referents points to another object which is also referenced by an
4107   // object discovered by the STW ref processor.
4108   double preserve_cm_referents_time = 0.0;
4109 
4110   // To avoid spawning task when there is no work to do, check that
4111   // a concurrent cycle is active and that some references have been
4112   // discovered.
4113   if (concurrent_mark()->cm_thread()->during_cycle() &&
4114       ref_processor_cm()->has_discovered_references()) {
4115     double preserve_cm_referents_start = os::elapsedTime();
4116     uint no_of_gc_workers = workers()->active_workers();
4117     G1ParPreserveCMReferentsTask keep_cm_referents(this,
4118                                                    per_thread_states,
4119                                                    no_of_gc_workers,
4120                                                    _task_queues);
4121     workers()->run_task(&keep_cm_referents);
4122     preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4123   }
4124 
4125   g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4126 }
4127 
4128 // Weak Reference processing during an evacuation pause (part 1).
4129 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4130   double ref_proc_start = os::elapsedTime();
4131 
4132   ReferenceProcessor* rp = _ref_processor_stw;
4133   assert(rp->discovery_enabled(), "should have been enabled");
4134 
4135   // Closure to test whether a referent is alive.
4136   G1STWIsAliveClosure is_alive(this);
4137 
4138   // Even when parallel reference processing is enabled, the processing
4139   // of JNI refs is serial and performed serially by the current thread
4140   // rather than by a worker. The following PSS will be used for processing
4141   // JNI refs.
4142 
4143   // Use only a single queue for this PSS.
4144   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4145   pss->set_ref_processor(NULL);
4146   assert(pss->queue_is_empty(), "pre-condition");
4147 
4148   // Keep alive closure.
4149   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4150 
4151   // Serial Complete GC closure
4152   G1STWDrainQueueClosure drain_queue(this, pss);
4153 
4154   // Setup the soft refs policy...
4155   rp->setup_policy(false);
4156 
4157   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4158 
4159   ReferenceProcessorStats stats;
4160   if (!rp->processing_is_mt()) {
4161     // Serial reference processing...
4162     stats = rp->process_discovered_references(&is_alive,
4163                                               &keep_alive,
4164                                               &drain_queue,
4165                                               NULL,
4166                                               pt);
4167   } else {
4168     uint no_of_gc_workers = workers()->active_workers();
4169 
4170     // Parallel reference processing
4171     assert(no_of_gc_workers <= rp->max_num_q(),
4172            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4173            no_of_gc_workers,  rp->max_num_q());
4174 
4175     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4176     stats = rp->process_discovered_references(&is_alive,
4177                                               &keep_alive,
4178                                               &drain_queue,
4179                                               &par_task_executor,
4180                                               pt);
4181   }
4182 
4183   _gc_tracer_stw->report_gc_reference_stats(stats);
4184 
4185   // We have completed copying any necessary live referent objects.
4186   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4187 
4188   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4189   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4190 }
4191 
4192 // Weak Reference processing during an evacuation pause (part 2).
4193 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4194   double ref_enq_start = os::elapsedTime();
4195 
4196   ReferenceProcessor* rp = _ref_processor_stw;
4197   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4198 
4199   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4200 
4201   // Now enqueue any remaining on the discovered lists on to
4202   // the pending list.
4203   if (!rp->processing_is_mt()) {
4204     // Serial reference processing...
4205     rp->enqueue_discovered_references(NULL, pt);
4206   } else {
4207     // Parallel reference enqueueing
4208 
4209     uint n_workers = workers()->active_workers();
4210 
4211     assert(n_workers <= rp->max_num_q(),
4212            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4213            n_workers,  rp->max_num_q());
4214 
4215     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4216     rp->enqueue_discovered_references(&par_task_executor, pt);
4217   }
4218 
4219   rp->verify_no_references_recorded();
4220   assert(!rp->discovery_enabled(), "should have been disabled");
4221 
4222   // If during an initial mark pause we install a pending list head which is not otherwise reachable
4223   // ensure that it is marked in the bitmap for concurrent marking to discover.
4224   if (collector_state()->during_initial_mark_pause()) {
4225     oop pll_head = Universe::reference_pending_list();
4226     if (pll_head != NULL) {
4227       _cm->mark_in_next_bitmap(pll_head);
4228     }
4229   }
4230 
4231   // FIXME
4232   // CM's reference processing also cleans up the string and symbol tables.
4233   // Should we do that here also? We could, but it is a serial operation
4234   // and could significantly increase the pause time.
4235 
4236   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4237   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4238 }
4239 
4240 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4241   double merge_pss_time_start = os::elapsedTime();
4242   per_thread_states->flush();
4243   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4244 }
4245 
4246 void G1CollectedHeap::pre_evacuate_collection_set() {
4247   _expand_heap_after_alloc_failure = true;
4248   _evacuation_failed = false;
4249 
4250   // Disable the hot card cache.
4251   _hot_card_cache->reset_hot_cache_claimed_index();
4252   _hot_card_cache->set_use_cache(false);
4253 
4254   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4255   _preserved_marks_set.assert_empty();
4256 
4257   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4258 
4259   // InitialMark needs claim bits to keep track of the marked-through CLDs.
4260   if (collector_state()->during_initial_mark_pause()) {
4261     double start_clear_claimed_marks = os::elapsedTime();
4262 
4263     ClassLoaderDataGraph::clear_claimed_marks();
4264 
4265     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4266     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4267   }
4268 }
4269 
4270 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4271   // Should G1EvacuationFailureALot be in effect for this GC?
4272   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4273 
4274   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4275 
4276   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4277 
4278   double start_par_time_sec = os::elapsedTime();
4279   double end_par_time_sec;
4280 
4281   {
4282     const uint n_workers = workers()->active_workers();
4283     G1RootProcessor root_processor(this, n_workers);
4284     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4285 
4286     print_termination_stats_hdr();
4287 
4288     workers()->run_task(&g1_par_task);
4289     end_par_time_sec = os::elapsedTime();
4290 
4291     // Closing the inner scope will execute the destructor
4292     // for the G1RootProcessor object. We record the current
4293     // elapsed time before closing the scope so that time
4294     // taken for the destructor is NOT included in the
4295     // reported parallel time.
4296   }
4297 
4298   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4299   phase_times->record_par_time(par_time_ms);
4300 
4301   double code_root_fixup_time_ms =
4302         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4303   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4304 }
4305 
4306 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4307   // Process any discovered reference objects - we have
4308   // to do this _before_ we retire the GC alloc regions
4309   // as we may have to copy some 'reachable' referent
4310   // objects (and their reachable sub-graphs) that were
4311   // not copied during the pause.
4312   if (g1_policy()->should_process_references()) {
4313     preserve_cm_referents(per_thread_states);
4314     process_discovered_references(per_thread_states);
4315   } else {
4316     ref_processor_stw()->verify_no_references_recorded();
4317   }
4318 
4319   G1STWIsAliveClosure is_alive(this);
4320   G1KeepAliveClosure keep_alive(this);
4321 
4322   {
4323     double start = os::elapsedTime();
4324 
4325     WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4326 
4327     double time_ms = (os::elapsedTime() - start) * 1000.0;
4328     g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4329   }
4330 
4331   if (G1StringDedup::is_enabled()) {
4332     double fixup_start = os::elapsedTime();
4333 
4334     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4335 
4336     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4337     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4338   }
4339 
4340   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4341 
4342   if (evacuation_failed()) {
4343     restore_after_evac_failure();
4344 
4345     // Reset the G1EvacuationFailureALot counters and flags
4346     // Note: the values are reset only when an actual
4347     // evacuation failure occurs.
4348     NOT_PRODUCT(reset_evacuation_should_fail();)
4349   }
4350 
4351   _preserved_marks_set.assert_empty();
4352 
4353   // Enqueue any remaining references remaining on the STW
4354   // reference processor's discovered lists. We need to do
4355   // this after the card table is cleaned (and verified) as
4356   // the act of enqueueing entries on to the pending list
4357   // will log these updates (and dirty their associated
4358   // cards). We need these updates logged to update any
4359   // RSets.
4360   if (g1_policy()->should_process_references()) {
4361     enqueue_discovered_references(per_thread_states);
4362   } else {
4363     g1_policy()->phase_times()->record_ref_enq_time(0);
4364   }
4365 
4366   _allocator->release_gc_alloc_regions(evacuation_info);
4367 
4368   merge_per_thread_state_info(per_thread_states);
4369 
4370   // Reset and re-enable the hot card cache.
4371   // Note the counts for the cards in the regions in the
4372   // collection set are reset when the collection set is freed.
4373   _hot_card_cache->reset_hot_cache();
4374   _hot_card_cache->set_use_cache(true);
4375 
4376   purge_code_root_memory();
4377 
4378   redirty_logged_cards();
4379 #if COMPILER2_OR_JVMCI
4380   double start = os::elapsedTime();
4381   DerivedPointerTable::update_pointers();
4382   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4383 #endif
4384   g1_policy()->print_age_table();
4385 }
4386 
4387 void G1CollectedHeap::record_obj_copy_mem_stats() {
4388   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4389 
4390   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4391                                                create_g1_evac_summary(&_old_evac_stats));
4392 }
4393 
4394 void G1CollectedHeap::free_region(HeapRegion* hr,
4395                                   FreeRegionList* free_list,
4396                                   bool skip_remset,
4397                                   bool skip_hot_card_cache,
4398                                   bool locked) {
4399   assert(!hr->is_free(), "the region should not be free");
4400   assert(!hr->is_empty(), "the region should not be empty");
4401   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4402   assert(free_list != NULL, "pre-condition");
4403 
4404   if (G1VerifyBitmaps) {
4405     MemRegion mr(hr->bottom(), hr->end());
4406     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4407   }
4408 
4409   // Clear the card counts for this region.
4410   // Note: we only need to do this if the region is not young
4411   // (since we don't refine cards in young regions).
4412   if (!skip_hot_card_cache && !hr->is_young()) {
4413     _hot_card_cache->reset_card_counts(hr);
4414   }
4415   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4416   free_list->add_ordered(hr);
4417 }
4418 
4419 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4420                                             FreeRegionList* free_list,
4421                                             bool skip_remset) {
4422   assert(hr->is_humongous(), "this is only for humongous regions");
4423   assert(free_list != NULL, "pre-condition");
4424   hr->clear_humongous();
4425   free_region(hr, free_list, skip_remset);
4426 }
4427 
4428 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4429                                            const uint humongous_regions_removed) {
4430   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4431     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4432     _old_set.bulk_remove(old_regions_removed);
4433     _humongous_set.bulk_remove(humongous_regions_removed);
4434   }
4435 
4436 }
4437 
4438 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4439   assert(list != NULL, "list can't be null");
4440   if (!list->is_empty()) {
4441     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4442     _hrm.insert_list_into_free_list(list);
4443   }
4444 }
4445 
4446 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4447   decrease_used(bytes);
4448 }
4449 
4450 class G1ParScrubRemSetTask: public AbstractGangTask {
4451 protected:
4452   G1RemSet* _g1rs;
4453   HeapRegionClaimer _hrclaimer;
4454 
4455 public:
4456   G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4457     AbstractGangTask("G1 ScrubRS"),
4458     _g1rs(g1_rs),
4459     _hrclaimer(num_workers) {
4460   }
4461 
4462   void work(uint worker_id) {
4463     _g1rs->scrub(worker_id, &_hrclaimer);
4464   }
4465 };
4466 
4467 void G1CollectedHeap::scrub_rem_set() {
4468   uint num_workers = workers()->active_workers();
4469   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4470   workers()->run_task(&g1_par_scrub_rs_task);
4471 }
4472 
4473 class G1FreeCollectionSetTask : public AbstractGangTask {
4474 private:
4475 
4476   // Closure applied to all regions in the collection set to do work that needs to
4477   // be done serially in a single thread.
4478   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4479   private:
4480     EvacuationInfo* _evacuation_info;
4481     const size_t* _surviving_young_words;
4482 
4483     // Bytes used in successfully evacuated regions before the evacuation.
4484     size_t _before_used_bytes;
4485     // Bytes used in unsucessfully evacuated regions before the evacuation
4486     size_t _after_used_bytes;
4487 
4488     size_t _bytes_allocated_in_old_since_last_gc;
4489 
4490     size_t _failure_used_words;
4491     size_t _failure_waste_words;
4492 
4493     FreeRegionList _local_free_list;
4494   public:
4495     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4496       HeapRegionClosure(),
4497       _evacuation_info(evacuation_info),
4498       _surviving_young_words(surviving_young_words),
4499       _before_used_bytes(0),
4500       _after_used_bytes(0),
4501       _bytes_allocated_in_old_since_last_gc(0),
4502       _failure_used_words(0),
4503       _failure_waste_words(0),
4504       _local_free_list("Local Region List for CSet Freeing") {
4505     }
4506 
4507     virtual bool do_heap_region(HeapRegion* r) {
4508       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4509 
4510       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4511       g1h->clear_in_cset(r);
4512 
4513       if (r->is_young()) {
4514         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4515                "Young index %d is wrong for region %u of type %s with %u young regions",
4516                r->young_index_in_cset(),
4517                r->hrm_index(),
4518                r->get_type_str(),
4519                g1h->collection_set()->young_region_length());
4520         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4521         r->record_surv_words_in_group(words_survived);
4522       }
4523 
4524       if (!r->evacuation_failed()) {
4525         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4526         _before_used_bytes += r->used();
4527         g1h->free_region(r,
4528                          &_local_free_list,
4529                          true, /* skip_remset */
4530                          true, /* skip_hot_card_cache */
4531                          true  /* locked */);
4532       } else {
4533         r->uninstall_surv_rate_group();
4534         r->set_young_index_in_cset(-1);
4535         r->set_evacuation_failed(false);
4536         // When moving a young gen region to old gen, we "allocate" that whole region
4537         // there. This is in addition to any already evacuated objects. Notify the
4538         // policy about that.
4539         // Old gen regions do not cause an additional allocation: both the objects
4540         // still in the region and the ones already moved are accounted for elsewhere.
4541         if (r->is_young()) {
4542           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4543         }
4544         // The region is now considered to be old.
4545         r->set_old();
4546         // Do some allocation statistics accounting. Regions that failed evacuation
4547         // are always made old, so there is no need to update anything in the young
4548         // gen statistics, but we need to update old gen statistics.
4549         size_t used_words = r->marked_bytes() / HeapWordSize;
4550 
4551         _failure_used_words += used_words;
4552         _failure_waste_words += HeapRegion::GrainWords - used_words;
4553 
4554         g1h->old_set_add(r);
4555         _after_used_bytes += r->used();
4556       }
4557       return false;
4558     }
4559 
4560     void complete_work() {
4561       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4562 
4563       _evacuation_info->set_regions_freed(_local_free_list.length());
4564       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4565 
4566       g1h->prepend_to_freelist(&_local_free_list);
4567       g1h->decrement_summary_bytes(_before_used_bytes);
4568 
4569       G1Policy* policy = g1h->g1_policy();
4570       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4571 
4572       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4573     }
4574   };
4575 
4576   G1CollectionSet* _collection_set;
4577   G1SerialFreeCollectionSetClosure _cl;
4578   const size_t* _surviving_young_words;
4579 
4580   size_t _rs_lengths;
4581 
4582   volatile jint _serial_work_claim;
4583 
4584   struct WorkItem {
4585     uint region_idx;
4586     bool is_young;
4587     bool evacuation_failed;
4588 
4589     WorkItem(HeapRegion* r) {
4590       region_idx = r->hrm_index();
4591       is_young = r->is_young();
4592       evacuation_failed = r->evacuation_failed();
4593     }
4594   };
4595 
4596   volatile size_t _parallel_work_claim;
4597   size_t _num_work_items;
4598   WorkItem* _work_items;
4599 
4600   void do_serial_work() {
4601     // Need to grab the lock to be allowed to modify the old region list.
4602     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4603     _collection_set->iterate(&_cl);
4604   }
4605 
4606   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4607     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4608 
4609     HeapRegion* r = g1h->region_at(region_idx);
4610     assert(!g1h->is_on_master_free_list(r), "sanity");
4611 
4612     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4613 
4614     if (!is_young) {
4615       g1h->_hot_card_cache->reset_card_counts(r);
4616     }
4617 
4618     if (!evacuation_failed) {
4619       r->rem_set()->clear_locked();
4620     }
4621   }
4622 
4623   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4624   private:
4625     size_t _cur_idx;
4626     WorkItem* _work_items;
4627   public:
4628     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4629 
4630     virtual bool do_heap_region(HeapRegion* r) {
4631       _work_items[_cur_idx++] = WorkItem(r);
4632       return false;
4633     }
4634   };
4635 
4636   void prepare_work() {
4637     G1PrepareFreeCollectionSetClosure cl(_work_items);
4638     _collection_set->iterate(&cl);
4639   }
4640 
4641   void complete_work() {
4642     _cl.complete_work();
4643 
4644     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4645     policy->record_max_rs_lengths(_rs_lengths);
4646     policy->cset_regions_freed();
4647   }
4648 public:
4649   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4650     AbstractGangTask("G1 Free Collection Set"),
4651     _cl(evacuation_info, surviving_young_words),
4652     _collection_set(collection_set),
4653     _surviving_young_words(surviving_young_words),
4654     _serial_work_claim(0),
4655     _rs_lengths(0),
4656     _parallel_work_claim(0),
4657     _num_work_items(collection_set->region_length()),
4658     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4659     prepare_work();
4660   }
4661 
4662   ~G1FreeCollectionSetTask() {
4663     complete_work();
4664     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4665   }
4666 
4667   // Chunk size for work distribution. The chosen value has been determined experimentally
4668   // to be a good tradeoff between overhead and achievable parallelism.
4669   static uint chunk_size() { return 32; }
4670 
4671   virtual void work(uint worker_id) {
4672     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4673 
4674     // Claim serial work.
4675     if (_serial_work_claim == 0) {
4676       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4677       if (value == 0) {
4678         double serial_time = os::elapsedTime();
4679         do_serial_work();
4680         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4681       }
4682     }
4683 
4684     // Start parallel work.
4685     double young_time = 0.0;
4686     bool has_young_time = false;
4687     double non_young_time = 0.0;
4688     bool has_non_young_time = false;
4689 
4690     while (true) {
4691       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4692       size_t cur = end - chunk_size();
4693 
4694       if (cur >= _num_work_items) {
4695         break;
4696       }
4697 
4698       double start_time = os::elapsedTime();
4699 
4700       end = MIN2(end, _num_work_items);
4701 
4702       for (; cur < end; cur++) {
4703         bool is_young = _work_items[cur].is_young;
4704 
4705         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4706 
4707         double end_time = os::elapsedTime();
4708         double time_taken = end_time - start_time;
4709         if (is_young) {
4710           young_time += time_taken;
4711           has_young_time = true;
4712         } else {
4713           non_young_time += time_taken;
4714           has_non_young_time = true;
4715         }
4716         start_time = end_time;
4717       }
4718     }
4719 
4720     if (has_young_time) {
4721       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4722     }
4723     if (has_non_young_time) {
4724       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4725     }
4726   }
4727 };
4728 
4729 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4730   _eden.clear();
4731 
4732   double free_cset_start_time = os::elapsedTime();
4733 
4734   {
4735     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4736     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4737 
4738     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4739 
4740     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4741                         cl.name(),
4742                         num_workers,
4743                         _collection_set.region_length());
4744     workers()->run_task(&cl, num_workers);
4745   }
4746   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4747 
4748   collection_set->clear();
4749 }
4750 
4751 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4752  private:
4753   FreeRegionList* _free_region_list;
4754   HeapRegionSet* _proxy_set;
4755   uint _humongous_objects_reclaimed;
4756   uint _humongous_regions_reclaimed;
4757   size_t _freed_bytes;
4758  public:
4759 
4760   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4761     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4762   }
4763 
4764   virtual bool do_heap_region(HeapRegion* r) {
4765     if (!r->is_starts_humongous()) {
4766       return false;
4767     }
4768 
4769     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4770 
4771     oop obj = (oop)r->bottom();
4772     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4773 
4774     // The following checks whether the humongous object is live are sufficient.
4775     // The main additional check (in addition to having a reference from the roots
4776     // or the young gen) is whether the humongous object has a remembered set entry.
4777     //
4778     // A humongous object cannot be live if there is no remembered set for it
4779     // because:
4780     // - there can be no references from within humongous starts regions referencing
4781     // the object because we never allocate other objects into them.
4782     // (I.e. there are no intra-region references that may be missed by the
4783     // remembered set)
4784     // - as soon there is a remembered set entry to the humongous starts region
4785     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4786     // until the end of a concurrent mark.
4787     //
4788     // It is not required to check whether the object has been found dead by marking
4789     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4790     // all objects allocated during that time are considered live.
4791     // SATB marking is even more conservative than the remembered set.
4792     // So if at this point in the collection there is no remembered set entry,
4793     // nobody has a reference to it.
4794     // At the start of collection we flush all refinement logs, and remembered sets
4795     // are completely up-to-date wrt to references to the humongous object.
4796     //
4797     // Other implementation considerations:
4798     // - never consider object arrays at this time because they would pose
4799     // considerable effort for cleaning up the the remembered sets. This is
4800     // required because stale remembered sets might reference locations that
4801     // are currently allocated into.
4802     uint region_idx = r->hrm_index();
4803     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4804         !r->rem_set()->is_empty()) {
4805       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",
4806                                region_idx,
4807                                (size_t)obj->size() * HeapWordSize,
4808                                p2i(r->bottom()),
4809                                r->rem_set()->occupied(),
4810                                r->rem_set()->strong_code_roots_list_length(),
4811                                next_bitmap->is_marked(r->bottom()),
4812                                g1h->is_humongous_reclaim_candidate(region_idx),
4813                                obj->is_typeArray()
4814                               );
4815       return false;
4816     }
4817 
4818     guarantee(obj->is_typeArray(),
4819               "Only eagerly reclaiming type arrays is supported, but the object "
4820               PTR_FORMAT " is not.", p2i(r->bottom()));
4821 
4822     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",
4823                              region_idx,
4824                              (size_t)obj->size() * HeapWordSize,
4825                              p2i(r->bottom()),
4826                              r->rem_set()->occupied(),
4827                              r->rem_set()->strong_code_roots_list_length(),
4828                              next_bitmap->is_marked(r->bottom()),
4829                              g1h->is_humongous_reclaim_candidate(region_idx),
4830                              obj->is_typeArray()
4831                             );
4832 
4833     // Need to clear mark bit of the humongous object if already set.
4834     if (next_bitmap->is_marked(r->bottom())) {
4835       next_bitmap->clear(r->bottom());
4836     }
4837     _humongous_objects_reclaimed++;
4838     do {
4839       HeapRegion* next = g1h->next_region_in_humongous(r);
4840       _freed_bytes += r->used();
4841       r->set_containing_set(NULL);
4842       _humongous_regions_reclaimed++;
4843       g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4844       r = next;
4845     } while (r != NULL);
4846 
4847     return false;
4848   }
4849 
4850   uint humongous_objects_reclaimed() {
4851     return _humongous_objects_reclaimed;
4852   }
4853 
4854   uint humongous_regions_reclaimed() {
4855     return _humongous_regions_reclaimed;
4856   }
4857 
4858   size_t bytes_freed() const {
4859     return _freed_bytes;
4860   }
4861 };
4862 
4863 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4864   assert_at_safepoint(true);
4865 
4866   if (!G1EagerReclaimHumongousObjects ||
4867       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4868     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4869     return;
4870   }
4871 
4872   double start_time = os::elapsedTime();
4873 
4874   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4875 
4876   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4877   heap_region_iterate(&cl);
4878 
4879   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4880 
4881   G1HRPrinter* hrp = hr_printer();
4882   if (hrp->is_active()) {
4883     FreeRegionListIterator iter(&local_cleanup_list);
4884     while (iter.more_available()) {
4885       HeapRegion* hr = iter.get_next();
4886       hrp->cleanup(hr);
4887     }
4888   }
4889 
4890   prepend_to_freelist(&local_cleanup_list);
4891   decrement_summary_bytes(cl.bytes_freed());
4892 
4893   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4894                                                                     cl.humongous_objects_reclaimed());
4895 }
4896 
4897 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4898 public:
4899   virtual bool do_heap_region(HeapRegion* r) {
4900     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4901     G1CollectedHeap::heap()->clear_in_cset(r);
4902     r->set_young_index_in_cset(-1);
4903     return false;
4904   }
4905 };
4906 
4907 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4908   G1AbandonCollectionSetClosure cl;
4909   collection_set->iterate(&cl);
4910 
4911   collection_set->clear();
4912   collection_set->stop_incremental_building();
4913 }
4914 
4915 void G1CollectedHeap::set_free_regions_coming() {
4916   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4917 
4918   assert(!free_regions_coming(), "pre-condition");
4919   _free_regions_coming = true;
4920 }
4921 
4922 void G1CollectedHeap::reset_free_regions_coming() {
4923   assert(free_regions_coming(), "pre-condition");
4924 
4925   {
4926     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4927     _free_regions_coming = false;
4928     SecondaryFreeList_lock->notify_all();
4929   }
4930 
4931   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4932 }
4933 
4934 void G1CollectedHeap::wait_while_free_regions_coming() {
4935   // Most of the time we won't have to wait, so let's do a quick test
4936   // first before we take the lock.
4937   if (!free_regions_coming()) {
4938     return;
4939   }
4940 
4941   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4942 
4943   {
4944     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4945     while (free_regions_coming()) {
4946       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4947     }
4948   }
4949 
4950   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
4951 }
4952 
4953 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4954   return _allocator->is_retained_old_region(hr);
4955 }
4956 
4957 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4958   _eden.add(hr);
4959   _g1_policy->set_region_eden(hr);
4960 }
4961 
4962 #ifdef ASSERT
4963 
4964 class NoYoungRegionsClosure: public HeapRegionClosure {
4965 private:
4966   bool _success;
4967 public:
4968   NoYoungRegionsClosure() : _success(true) { }
4969   bool do_heap_region(HeapRegion* r) {
4970     if (r->is_young()) {
4971       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4972                             p2i(r->bottom()), p2i(r->end()));
4973       _success = false;
4974     }
4975     return false;
4976   }
4977   bool success() { return _success; }
4978 };
4979 
4980 bool G1CollectedHeap::check_young_list_empty() {
4981   bool ret = (young_regions_count() == 0);
4982 
4983   NoYoungRegionsClosure closure;
4984   heap_region_iterate(&closure);
4985   ret = ret && closure.success();
4986 
4987   return ret;
4988 }
4989 
4990 #endif // ASSERT
4991 
4992 class TearDownRegionSetsClosure : public HeapRegionClosure {
4993 private:
4994   HeapRegionSet *_old_set;
4995 
4996 public:
4997   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4998 
4999   bool do_heap_region(HeapRegion* r) {
5000     if (r->is_old()) {
5001       _old_set->remove(r);
5002     } else if(r->is_young()) {
5003       r->uninstall_surv_rate_group();
5004     } else {
5005       // We ignore free regions, we'll empty the free list afterwards.
5006       // We ignore humongous regions, we're not tearing down the
5007       // humongous regions set.
5008       assert(r->is_free() || r->is_humongous(),
5009              "it cannot be another type");
5010     }
5011     return false;
5012   }
5013 
5014   ~TearDownRegionSetsClosure() {
5015     assert(_old_set->is_empty(), "post-condition");
5016   }
5017 };
5018 
5019 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5020   assert_at_safepoint(true /* should_be_vm_thread */);
5021 
5022   if (!free_list_only) {
5023     TearDownRegionSetsClosure cl(&_old_set);
5024     heap_region_iterate(&cl);
5025 
5026     // Note that emptying the _young_list is postponed and instead done as
5027     // the first step when rebuilding the regions sets again. The reason for
5028     // this is that during a full GC string deduplication needs to know if
5029     // a collected region was young or old when the full GC was initiated.
5030   }
5031   _hrm.remove_all_free_regions();
5032 }
5033 
5034 void G1CollectedHeap::increase_used(size_t bytes) {
5035   _summary_bytes_used += bytes;
5036 }
5037 
5038 void G1CollectedHeap::decrease_used(size_t bytes) {
5039   assert(_summary_bytes_used >= bytes,
5040          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5041          _summary_bytes_used, bytes);
5042   _summary_bytes_used -= bytes;
5043 }
5044 
5045 void G1CollectedHeap::set_used(size_t bytes) {
5046   _summary_bytes_used = bytes;
5047 }
5048 
5049 class RebuildRegionSetsClosure : public HeapRegionClosure {
5050 private:
5051   bool            _free_list_only;
5052   HeapRegionSet*   _old_set;
5053   HeapRegionManager*   _hrm;
5054   size_t          _total_used;
5055 
5056 public:
5057   RebuildRegionSetsClosure(bool free_list_only,
5058                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5059     _free_list_only(free_list_only),
5060     _old_set(old_set), _hrm(hrm), _total_used(0) {
5061     assert(_hrm->num_free_regions() == 0, "pre-condition");
5062     if (!free_list_only) {
5063       assert(_old_set->is_empty(), "pre-condition");
5064     }
5065   }
5066 
5067   bool do_heap_region(HeapRegion* r) {
5068     if (r->is_empty()) {
5069       // Add free regions to the free list
5070       r->set_free();
5071       r->set_allocation_context(AllocationContext::system());
5072       _hrm->insert_into_free_list(r);
5073     } else if (!_free_list_only) {
5074 
5075       if (r->is_humongous()) {
5076         // We ignore humongous regions. We left the humongous set unchanged.
5077       } else {
5078         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5079         // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5080         r->move_to_old();
5081         _old_set->add(r);
5082       }
5083       _total_used += r->used();
5084     }
5085 
5086     return false;
5087   }
5088 
5089   size_t total_used() {
5090     return _total_used;
5091   }
5092 };
5093 
5094 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5095   assert_at_safepoint(true /* should_be_vm_thread */);
5096 
5097   if (!free_list_only) {
5098     _eden.clear();
5099     _survivor.clear();
5100   }
5101 
5102   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5103   heap_region_iterate(&cl);
5104 
5105   if (!free_list_only) {
5106     set_used(cl.total_used());
5107     if (_archive_allocator != NULL) {
5108       _archive_allocator->clear_used();
5109     }
5110   }
5111   assert(used_unlocked() == recalculate_used(),
5112          "inconsistent used_unlocked(), "
5113          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5114          used_unlocked(), recalculate_used());
5115 }
5116 
5117 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5118   HeapRegion* hr = heap_region_containing(p);
5119   return hr->is_in(p);
5120 }
5121 
5122 // Methods for the mutator alloc region
5123 
5124 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5125                                                       bool force) {
5126   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5127   bool should_allocate = g1_policy()->should_allocate_mutator_region();
5128   if (force || should_allocate) {
5129     HeapRegion* new_alloc_region = new_region(word_size,
5130                                               false /* is_old */,
5131                                               false /* do_expand */);
5132     if (new_alloc_region != NULL) {
5133       set_region_short_lived_locked(new_alloc_region);
5134       _hr_printer.alloc(new_alloc_region, !should_allocate);
5135       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5136       return new_alloc_region;
5137     }
5138   }
5139   return NULL;
5140 }
5141 
5142 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5143                                                   size_t allocated_bytes) {
5144   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5145   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5146 
5147   collection_set()->add_eden_region(alloc_region);
5148   increase_used(allocated_bytes);
5149   _hr_printer.retire(alloc_region);
5150   // We update the eden sizes here, when the region is retired,
5151   // instead of when it's allocated, since this is the point that its
5152   // used space has been recored in _summary_bytes_used.
5153   g1mm()->update_eden_size();
5154 }
5155 
5156 // Methods for the GC alloc regions
5157 
5158 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5159   if (dest.is_old()) {
5160     return true;
5161   } else {
5162     return survivor_regions_count() < g1_policy()->max_survivor_regions();
5163   }
5164 }
5165 
5166 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5167   assert(FreeList_lock->owned_by_self(), "pre-condition");
5168 
5169   if (!has_more_regions(dest)) {
5170     return NULL;
5171   }
5172 
5173   const bool is_survivor = dest.is_young();
5174 
5175   HeapRegion* new_alloc_region = new_region(word_size,
5176                                             !is_survivor,
5177                                             true /* do_expand */);
5178   if (new_alloc_region != NULL) {
5179     // We really only need to do this for old regions given that we
5180     // should never scan survivors. But it doesn't hurt to do it
5181     // for survivors too.
5182     new_alloc_region->record_timestamp();
5183     if (is_survivor) {
5184       new_alloc_region->set_survivor();
5185       _survivor.add(new_alloc_region);
5186       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5187     } else {
5188       new_alloc_region->set_old();
5189       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5190     }
5191     _hr_printer.alloc(new_alloc_region);
5192     bool during_im = collector_state()->during_initial_mark_pause();
5193     new_alloc_region->note_start_of_copying(during_im);
5194     return new_alloc_region;
5195   }
5196   return NULL;
5197 }
5198 
5199 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5200                                              size_t allocated_bytes,
5201                                              InCSetState dest) {
5202   bool during_im = collector_state()->during_initial_mark_pause();
5203   alloc_region->note_end_of_copying(during_im);
5204   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5205   if (dest.is_old()) {
5206     _old_set.add(alloc_region);
5207   }
5208   _hr_printer.retire(alloc_region);
5209 }
5210 
5211 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5212   bool expanded = false;
5213   uint index = _hrm.find_highest_free(&expanded);
5214 
5215   if (index != G1_NO_HRM_INDEX) {
5216     if (expanded) {
5217       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5218                                 HeapRegion::GrainWords * HeapWordSize);
5219     }
5220     _hrm.allocate_free_regions_starting_at(index, 1);
5221     return region_at(index);
5222   }
5223   return NULL;
5224 }
5225 
5226 // Optimized nmethod scanning
5227 
5228 class RegisterNMethodOopClosure: public OopClosure {
5229   G1CollectedHeap* _g1h;
5230   nmethod* _nm;
5231 
5232   template <class T> void do_oop_work(T* p) {
5233     T heap_oop = oopDesc::load_heap_oop(p);
5234     if (!oopDesc::is_null(heap_oop)) {
5235       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5236       HeapRegion* hr = _g1h->heap_region_containing(obj);
5237       assert(!hr->is_continues_humongous(),
5238              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5239              " starting at " HR_FORMAT,
5240              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5241 
5242       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5243       hr->add_strong_code_root_locked(_nm);
5244     }
5245   }
5246 
5247 public:
5248   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5249     _g1h(g1h), _nm(nm) {}
5250 
5251   void do_oop(oop* p)       { do_oop_work(p); }
5252   void do_oop(narrowOop* p) { do_oop_work(p); }
5253 };
5254 
5255 class UnregisterNMethodOopClosure: public OopClosure {
5256   G1CollectedHeap* _g1h;
5257   nmethod* _nm;
5258 
5259   template <class T> void do_oop_work(T* p) {
5260     T heap_oop = oopDesc::load_heap_oop(p);
5261     if (!oopDesc::is_null(heap_oop)) {
5262       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5263       HeapRegion* hr = _g1h->heap_region_containing(obj);
5264       assert(!hr->is_continues_humongous(),
5265              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5266              " starting at " HR_FORMAT,
5267              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5268 
5269       hr->remove_strong_code_root(_nm);
5270     }
5271   }
5272 
5273 public:
5274   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5275     _g1h(g1h), _nm(nm) {}
5276 
5277   void do_oop(oop* p)       { do_oop_work(p); }
5278   void do_oop(narrowOop* p) { do_oop_work(p); }
5279 };
5280 
5281 // Returns true if the reference points to an object that
5282 // can move in an incremental collection.
5283 bool G1CollectedHeap::is_scavengable(oop obj) {
5284   HeapRegion* hr = heap_region_containing(obj);
5285   return !hr->is_pinned();
5286 }
5287 
5288 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5289   guarantee(nm != NULL, "sanity");
5290   RegisterNMethodOopClosure reg_cl(this, nm);
5291   nm->oops_do(&reg_cl);
5292 }
5293 
5294 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5295   guarantee(nm != NULL, "sanity");
5296   UnregisterNMethodOopClosure reg_cl(this, nm);
5297   nm->oops_do(&reg_cl, true);
5298 }
5299 
5300 void G1CollectedHeap::purge_code_root_memory() {
5301   double purge_start = os::elapsedTime();
5302   G1CodeRootSet::purge();
5303   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5304   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5305 }
5306 
5307 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5308   G1CollectedHeap* _g1h;
5309 
5310 public:
5311   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5312     _g1h(g1h) {}
5313 
5314   void do_code_blob(CodeBlob* cb) {
5315     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5316     if (nm == NULL) {
5317       return;
5318     }
5319 
5320     if (ScavengeRootsInCode) {
5321       _g1h->register_nmethod(nm);
5322     }
5323   }
5324 };
5325 
5326 void G1CollectedHeap::rebuild_strong_code_roots() {
5327   RebuildStrongCodeRootClosure blob_cl(this);
5328   CodeCache::blobs_do(&blob_cl);
5329 }
5330 
5331 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5332   GrowableArray<GCMemoryManager*> memory_managers(2);
5333   memory_managers.append(&_memory_manager);
5334   memory_managers.append(&_full_gc_memory_manager);
5335   return memory_managers;
5336 }
5337 
5338 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5339   GrowableArray<MemoryPool*> memory_pools(3);
5340   memory_pools.append(_eden_pool);
5341   memory_pools.append(_survivor_pool);
5342   memory_pools.append(_old_pool);
5343   return memory_pools;
5344 }