rev 48000 : [mq]: open.patch

   1 /*
   2  * Copyright (c) 2001, 2017, 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   uint dummy_gc_count_before;
 449   uint dummy_gclocker_retry_count = 0;
 450   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 451 }
 452 
 453 HeapWord*
 454 G1CollectedHeap::mem_allocate(size_t word_size,
 455                               bool*  gc_overhead_limit_was_exceeded) {
 456   assert_heap_not_locked_and_not_at_safepoint();
 457 
 458   // Loop until the allocation is satisfied, or unsatisfied after GC.
 459   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 460     uint gc_count_before;
 461 
 462     HeapWord* result = NULL;
 463     if (!is_humongous(word_size)) {
 464       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 465     } else {
 466       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 467     }
 468     if (result != NULL) {
 469       return result;
 470     }
 471 
 472     // Create the garbage collection operation...
 473     VM_G1CollectForAllocation op(gc_count_before, word_size);
 474     op.set_allocation_context(AllocationContext::current());
 475 
 476     // ...and get the VM thread to execute it.
 477     VMThread::execute(&op);
 478 
 479     if (op.prologue_succeeded() && op.pause_succeeded()) {
 480       // If the operation was successful we'll return the result even
 481       // if it is NULL. If the allocation attempt failed immediately
 482       // after a Full GC, it's unlikely we'll be able to allocate now.
 483       HeapWord* result = op.result();
 484       if (result != NULL && !is_humongous(word_size)) {
 485         // Allocations that take place on VM operations do not do any
 486         // card dirtying and we have to do it here. We only have to do
 487         // this for non-humongous allocations, though.
 488         dirty_young_block(result, word_size);
 489       }
 490       return result;
 491     } else {
 492       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 493         return NULL;
 494       }
 495       assert(op.result() == NULL,
 496              "the result should be NULL if the VM op did not succeed");
 497     }
 498 
 499     // Give a warning if we seem to be looping forever.
 500     if ((QueuedAllocationWarningCount > 0) &&
 501         (try_count % QueuedAllocationWarningCount == 0)) {
 502       log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
 503     }
 504   }
 505 
 506   ShouldNotReachHere();
 507   return NULL;
 508 }
 509 
 510 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 511                                                    AllocationContext_t context,
 512                                                    uint* gc_count_before_ret,
 513                                                    uint* gclocker_retry_count_ret) {
 514   // Make sure you read the note in attempt_allocation_humongous().
 515 
 516   assert_heap_not_locked_and_not_at_safepoint();
 517   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 518          "be called for humongous allocation requests");
 519 
 520   // We should only get here after the first-level allocation attempt
 521   // (attempt_allocation()) failed to allocate.
 522 
 523   // We will loop until a) we manage to successfully perform the
 524   // allocation or b) we successfully schedule a collection which
 525   // fails to perform the allocation. b) is the only case when we'll
 526   // return NULL.
 527   HeapWord* result = NULL;
 528   for (int try_count = 1; /* we'll return */; try_count += 1) {
 529     bool should_try_gc;
 530     uint gc_count_before;
 531 
 532     {
 533       MutexLockerEx x(Heap_lock);
 534       result = _allocator->attempt_allocation_locked(word_size, context);
 535       if (result != NULL) {
 536         return result;
 537       }
 538 
 539       if (GCLocker::is_active_and_needs_gc()) {
 540         if (g1_policy()->can_expand_young_list()) {
 541           // No need for an ergo verbose message here,
 542           // can_expand_young_list() does this when it returns true.
 543           result = _allocator->attempt_allocation_force(word_size, context);
 544           if (result != NULL) {
 545             return result;
 546           }
 547         }
 548         should_try_gc = false;
 549       } else {
 550         // The GCLocker may not be active but the GCLocker initiated
 551         // GC may not yet have been performed (GCLocker::needs_gc()
 552         // returns true). In this case we do not try this GC and
 553         // wait until the GCLocker initiated GC is performed, and
 554         // then retry the allocation.
 555         if (GCLocker::needs_gc()) {
 556           should_try_gc = false;
 557         } else {
 558           // Read the GC count while still holding the Heap_lock.
 559           gc_count_before = total_collections();
 560           should_try_gc = true;
 561         }
 562       }
 563     }
 564 
 565     if (should_try_gc) {
 566       bool succeeded;
 567       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 568                                    GCCause::_g1_inc_collection_pause);
 569       if (result != NULL) {
 570         assert(succeeded, "only way to get back a non-NULL result");
 571         return result;
 572       }
 573 
 574       if (succeeded) {
 575         // If we get here we successfully scheduled a collection which
 576         // failed to allocate. No point in trying to allocate
 577         // further. We'll just return NULL.
 578         MutexLockerEx x(Heap_lock);
 579         *gc_count_before_ret = total_collections();
 580         return NULL;
 581       }
 582     } else {
 583       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 584         MutexLockerEx x(Heap_lock);
 585         *gc_count_before_ret = total_collections();
 586         return NULL;
 587       }
 588       // The GCLocker is either active or the GCLocker initiated
 589       // GC has not yet been performed. Stall until it is and
 590       // then retry the allocation.
 591       GCLocker::stall_until_clear();
 592       (*gclocker_retry_count_ret) += 1;
 593     }
 594 
 595     // We can reach here if we were unsuccessful in scheduling a
 596     // collection (because another thread beat us to it) or if we were
 597     // stalled due to the GC locker. In either can we should retry the
 598     // allocation attempt in case another thread successfully
 599     // performed a collection and reclaimed enough space. We do the
 600     // first attempt (without holding the Heap_lock) here and the
 601     // follow-on attempt will be at the start of the next loop
 602     // iteration (after taking the Heap_lock).
 603     result = _allocator->attempt_allocation(word_size, context);
 604     if (result != NULL) {
 605       return result;
 606     }
 607 
 608     // Give a warning if we seem to be looping forever.
 609     if ((QueuedAllocationWarningCount > 0) &&
 610         (try_count % QueuedAllocationWarningCount == 0)) {
 611       log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
 612                       "retries %d times", try_count);
 613     }
 614   }
 615 
 616   ShouldNotReachHere();
 617   return NULL;
 618 }
 619 
 620 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
 621   assert_at_safepoint(true /* should_be_vm_thread */);
 622   if (_archive_allocator == NULL) {
 623     _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
 624   }
 625 }
 626 
 627 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 628   // Allocations in archive regions cannot be of a size that would be considered
 629   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 630   // may be different at archive-restore time.
 631   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 632 }
 633 
 634 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 635   assert_at_safepoint(true /* should_be_vm_thread */);
 636   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 637   if (is_archive_alloc_too_large(word_size)) {
 638     return NULL;
 639   }
 640   return _archive_allocator->archive_mem_allocate(word_size);
 641 }
 642 
 643 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 644                                               size_t end_alignment_in_bytes) {
 645   assert_at_safepoint(true /* should_be_vm_thread */);
 646   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 647 
 648   // Call complete_archive to do the real work, filling in the MemRegion
 649   // array with the archive regions.
 650   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 651   delete _archive_allocator;
 652   _archive_allocator = NULL;
 653 }
 654 
 655 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 656   assert(ranges != NULL, "MemRegion array NULL");
 657   assert(count != 0, "No MemRegions provided");
 658   MemRegion reserved = _hrm.reserved();
 659   for (size_t i = 0; i < count; i++) {
 660     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 661       return false;
 662     }
 663   }
 664   return true;
 665 }
 666 
 667 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
 668                                             size_t count,
 669                                             bool open) {
 670   assert(!is_init_completed(), "Expect to be called at JVM init time");
 671   assert(ranges != NULL, "MemRegion array NULL");
 672   assert(count != 0, "No MemRegions provided");
 673   MutexLockerEx x(Heap_lock);
 674 
 675   MemRegion reserved = _hrm.reserved();
 676   HeapWord* prev_last_addr = NULL;
 677   HeapRegion* prev_last_region = NULL;
 678 
 679   // Temporarily disable pretouching of heap pages. This interface is used
 680   // when mmap'ing archived heap data in, so pre-touching is wasted.
 681   FlagSetting fs(AlwaysPreTouch, false);
 682 
 683   // Enable archive object checking used by G1MarkSweep. We have to let it know
 684   // about each archive range, so that objects in those ranges aren't marked.
 685   G1ArchiveAllocator::enable_archive_object_check();
 686 
 687   // For each specified MemRegion range, allocate the corresponding G1
 688   // regions and mark them as archive regions. We expect the ranges
 689   // in ascending starting address order, without overlap.
 690   for (size_t i = 0; i < count; i++) {
 691     MemRegion curr_range = ranges[i];
 692     HeapWord* start_address = curr_range.start();
 693     size_t word_size = curr_range.word_size();
 694     HeapWord* last_address = curr_range.last();
 695     size_t commits = 0;
 696 
 697     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 698               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 699               p2i(start_address), p2i(last_address));
 700     guarantee(start_address > prev_last_addr,
 701               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 702               p2i(start_address), p2i(prev_last_addr));
 703     prev_last_addr = last_address;
 704 
 705     // Check for ranges that start in the same G1 region in which the previous
 706     // range ended, and adjust the start address so we don't try to allocate
 707     // the same region again. If the current range is entirely within that
 708     // region, skip it, just adjusting the recorded top.
 709     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 710     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 711       start_address = start_region->end();
 712       if (start_address > last_address) {
 713         increase_used(word_size * HeapWordSize);
 714         start_region->set_top(last_address + 1);
 715         continue;
 716       }
 717       start_region->set_top(start_address);
 718       curr_range = MemRegion(start_address, last_address + 1);
 719       start_region = _hrm.addr_to_region(start_address);
 720     }
 721 
 722     // Perform the actual region allocation, exiting if it fails.
 723     // Then note how much new space we have allocated.
 724     if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
 725       return false;
 726     }
 727     increase_used(word_size * HeapWordSize);
 728     if (commits != 0) {
 729       log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
 730                                 HeapRegion::GrainWords * HeapWordSize * commits);
 731 
 732     }
 733 
 734     // Mark each G1 region touched by the range as archive, add it to
 735     // the old set, and set the allocation context and top.
 736     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 737     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 738     prev_last_region = last_region;
 739 
 740     while (curr_region != NULL) {
 741       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 742              "Region already in use (index %u)", curr_region->hrm_index());
 743       curr_region->set_allocation_context(AllocationContext::system());
 744       if (open) {
 745         curr_region->set_open_archive();
 746       } else {
 747         curr_region->set_closed_archive();
 748       }
 749       _hr_printer.alloc(curr_region);
 750       _old_set.add(curr_region);
 751       HeapWord* top;
 752       HeapRegion* next_region;
 753       if (curr_region != last_region) {
 754         top = curr_region->end();
 755         next_region = _hrm.next_region_in_heap(curr_region);
 756       } else {
 757         top = last_address + 1;
 758         next_region = NULL;
 759       }
 760       curr_region->set_top(top);
 761       curr_region->set_first_dead(top);
 762       curr_region->set_end_of_live(top);
 763       curr_region = next_region;
 764     }
 765 
 766     // Notify mark-sweep of the archive
 767     G1ArchiveAllocator::set_range_archive(curr_range, open);
 768   }
 769   return true;
 770 }
 771 
 772 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 773   assert(!is_init_completed(), "Expect to be called at JVM init time");
 774   assert(ranges != NULL, "MemRegion array NULL");
 775   assert(count != 0, "No MemRegions provided");
 776   MemRegion reserved = _hrm.reserved();
 777   HeapWord *prev_last_addr = NULL;
 778   HeapRegion* prev_last_region = NULL;
 779 
 780   // For each MemRegion, create filler objects, if needed, in the G1 regions
 781   // that contain the address range. The address range actually within the
 782   // MemRegion will not be modified. That is assumed to have been initialized
 783   // elsewhere, probably via an mmap of archived heap data.
 784   MutexLockerEx x(Heap_lock);
 785   for (size_t i = 0; i < count; i++) {
 786     HeapWord* start_address = ranges[i].start();
 787     HeapWord* last_address = ranges[i].last();
 788 
 789     assert(reserved.contains(start_address) && reserved.contains(last_address),
 790            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 791            p2i(start_address), p2i(last_address));
 792     assert(start_address > prev_last_addr,
 793            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 794            p2i(start_address), p2i(prev_last_addr));
 795 
 796     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 797     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 798     HeapWord* bottom_address = start_region->bottom();
 799 
 800     // Check for a range beginning in the same region in which the
 801     // previous one ended.
 802     if (start_region == prev_last_region) {
 803       bottom_address = prev_last_addr + 1;
 804     }
 805 
 806     // Verify that the regions were all marked as archive regions by
 807     // alloc_archive_regions.
 808     HeapRegion* curr_region = start_region;
 809     while (curr_region != NULL) {
 810       guarantee(curr_region->is_archive(),
 811                 "Expected archive region at index %u", curr_region->hrm_index());
 812       if (curr_region != last_region) {
 813         curr_region = _hrm.next_region_in_heap(curr_region);
 814       } else {
 815         curr_region = NULL;
 816       }
 817     }
 818 
 819     prev_last_addr = last_address;
 820     prev_last_region = last_region;
 821 
 822     // Fill the memory below the allocated range with dummy object(s),
 823     // if the region bottom does not match the range start, or if the previous
 824     // range ended within the same G1 region, and there is a gap.
 825     if (start_address != bottom_address) {
 826       size_t fill_size = pointer_delta(start_address, bottom_address);
 827       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 828       increase_used(fill_size * HeapWordSize);
 829     }
 830   }
 831 }
 832 
 833 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
 834                                                      uint* gc_count_before_ret,
 835                                                      uint* gclocker_retry_count_ret) {
 836   assert_heap_not_locked_and_not_at_safepoint();
 837   assert(!is_humongous(word_size), "attempt_allocation() should not "
 838          "be called for humongous allocation requests");
 839 
 840   AllocationContext_t context = AllocationContext::current();
 841   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 842 
 843   if (result == NULL) {
 844     result = attempt_allocation_slow(word_size,
 845                                      context,
 846                                      gc_count_before_ret,
 847                                      gclocker_retry_count_ret);
 848   }
 849   assert_heap_not_locked();
 850   if (result != NULL) {
 851     dirty_young_block(result, word_size);
 852   }
 853   return result;
 854 }
 855 
 856 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 857   assert(!is_init_completed(), "Expect to be called at JVM init time");
 858   assert(ranges != NULL, "MemRegion array NULL");
 859   assert(count != 0, "No MemRegions provided");
 860   MemRegion reserved = _hrm.reserved();
 861   HeapWord* prev_last_addr = NULL;
 862   HeapRegion* prev_last_region = NULL;
 863   size_t size_used = 0;
 864   size_t uncommitted_regions = 0;
 865 
 866   // For each Memregion, free the G1 regions that constitute it, and
 867   // notify mark-sweep that the range is no longer to be considered 'archive.'
 868   MutexLockerEx x(Heap_lock);
 869   for (size_t i = 0; i < count; i++) {
 870     HeapWord* start_address = ranges[i].start();
 871     HeapWord* last_address = ranges[i].last();
 872 
 873     assert(reserved.contains(start_address) && reserved.contains(last_address),
 874            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 875            p2i(start_address), p2i(last_address));
 876     assert(start_address > prev_last_addr,
 877            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 878            p2i(start_address), p2i(prev_last_addr));
 879     size_used += ranges[i].byte_size();
 880     prev_last_addr = last_address;
 881 
 882     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 883     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 884 
 885     // Check for ranges that start in the same G1 region in which the previous
 886     // range ended, and adjust the start address so we don't try to free
 887     // the same region again. If the current range is entirely within that
 888     // region, skip it.
 889     if (start_region == prev_last_region) {
 890       start_address = start_region->end();
 891       if (start_address > last_address) {
 892         continue;
 893       }
 894       start_region = _hrm.addr_to_region(start_address);
 895     }
 896     prev_last_region = last_region;
 897 
 898     // After verifying that each region was marked as an archive region by
 899     // alloc_archive_regions, set it free and empty and uncommit it.
 900     HeapRegion* curr_region = start_region;
 901     while (curr_region != NULL) {
 902       guarantee(curr_region->is_archive(),
 903                 "Expected archive region at index %u", curr_region->hrm_index());
 904       uint curr_index = curr_region->hrm_index();
 905       _old_set.remove(curr_region);
 906       curr_region->set_free();
 907       curr_region->set_top(curr_region->bottom());
 908       if (curr_region != last_region) {
 909         curr_region = _hrm.next_region_in_heap(curr_region);
 910       } else {
 911         curr_region = NULL;
 912       }
 913       _hrm.shrink_at(curr_index, 1);
 914       uncommitted_regions++;
 915     }
 916 
 917     // Notify mark-sweep that this is no longer an archive range.
 918     G1ArchiveAllocator::set_range_archive(ranges[i], false);
 919   }
 920 
 921   if (uncommitted_regions != 0) {
 922     log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
 923                               HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 924   }
 925   decrease_used(size_used);
 926 }
 927 
 928 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 929                                                         uint* gc_count_before_ret,
 930                                                         uint* gclocker_retry_count_ret) {
 931   // The structure of this method has a lot of similarities to
 932   // attempt_allocation_slow(). The reason these two were not merged
 933   // into a single one is that such a method would require several "if
 934   // allocation is not humongous do this, otherwise do that"
 935   // conditional paths which would obscure its flow. In fact, an early
 936   // version of this code did use a unified method which was harder to
 937   // follow and, as a result, it had subtle bugs that were hard to
 938   // track down. So keeping these two methods separate allows each to
 939   // be more readable. It will be good to keep these two in sync as
 940   // much as possible.
 941 
 942   assert_heap_not_locked_and_not_at_safepoint();
 943   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 944          "should only be called for humongous allocations");
 945 
 946   // Humongous objects can exhaust the heap quickly, so we should check if we
 947   // need to start a marking cycle at each humongous object allocation. We do
 948   // the check before we do the actual allocation. The reason for doing it
 949   // before the allocation is that we avoid having to keep track of the newly
 950   // allocated memory while we do a GC.
 951   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 952                                            word_size)) {
 953     collect(GCCause::_g1_humongous_allocation);
 954   }
 955 
 956   // We will loop until a) we manage to successfully perform the
 957   // allocation or b) we successfully schedule a collection which
 958   // fails to perform the allocation. b) is the only case when we'll
 959   // return NULL.
 960   HeapWord* result = NULL;
 961   for (int try_count = 1; /* we'll return */; try_count += 1) {
 962     bool should_try_gc;
 963     uint gc_count_before;
 964 
 965     {
 966       MutexLockerEx x(Heap_lock);
 967 
 968       // Given that humongous objects are not allocated in young
 969       // regions, we'll first try to do the allocation without doing a
 970       // collection hoping that there's enough space in the heap.
 971       result = humongous_obj_allocate(word_size, AllocationContext::current());
 972       if (result != NULL) {
 973         size_t size_in_regions = humongous_obj_size_in_regions(word_size);
 974         g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
 975         return result;
 976       }
 977 
 978       if (GCLocker::is_active_and_needs_gc()) {
 979         should_try_gc = false;
 980       } else {
 981          // The GCLocker may not be active but the GCLocker initiated
 982         // GC may not yet have been performed (GCLocker::needs_gc()
 983         // returns true). In this case we do not try this GC and
 984         // wait until the GCLocker initiated GC is performed, and
 985         // then retry the allocation.
 986         if (GCLocker::needs_gc()) {
 987           should_try_gc = false;
 988         } else {
 989           // Read the GC count while still holding the Heap_lock.
 990           gc_count_before = total_collections();
 991           should_try_gc = true;
 992         }
 993       }
 994     }
 995 
 996     if (should_try_gc) {
 997       // If we failed to allocate the humongous object, we should try to
 998       // do a collection pause (if we're allowed) in case it reclaims
 999       // enough space for the allocation to succeed after the pause.
1000 
1001       bool succeeded;
1002       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1003                                    GCCause::_g1_humongous_allocation);
1004       if (result != NULL) {
1005         assert(succeeded, "only way to get back a non-NULL result");
1006         return result;
1007       }
1008 
1009       if (succeeded) {
1010         // If we get here we successfully scheduled a collection which
1011         // failed to allocate. No point in trying to allocate
1012         // further. We'll just return NULL.
1013         MutexLockerEx x(Heap_lock);
1014         *gc_count_before_ret = total_collections();
1015         return NULL;
1016       }
1017     } else {
1018       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1019         MutexLockerEx x(Heap_lock);
1020         *gc_count_before_ret = total_collections();
1021         return NULL;
1022       }
1023       // The GCLocker is either active or the GCLocker initiated
1024       // GC has not yet been performed. Stall until it is and
1025       // then retry the allocation.
1026       GCLocker::stall_until_clear();
1027       (*gclocker_retry_count_ret) += 1;
1028     }
1029 
1030     // We can reach here if we were unsuccessful in scheduling a
1031     // collection (because another thread beat us to it) or if we were
1032     // stalled due to the GC locker. In either can we should retry the
1033     // allocation attempt in case another thread successfully
1034     // performed a collection and reclaimed enough space.  Give a
1035     // warning if we seem to be looping forever.
1036 
1037     if ((QueuedAllocationWarningCount > 0) &&
1038         (try_count % QueuedAllocationWarningCount == 0)) {
1039       log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1040                       "retries %d times", try_count);
1041     }
1042   }
1043 
1044   ShouldNotReachHere();
1045   return NULL;
1046 }
1047 
1048 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1049                                                            AllocationContext_t context,
1050                                                            bool expect_null_mutator_alloc_region) {
1051   assert_at_safepoint(true /* should_be_vm_thread */);
1052   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1053          "the current alloc region was unexpectedly found to be non-NULL");
1054 
1055   if (!is_humongous(word_size)) {
1056     return _allocator->attempt_allocation_locked(word_size, context);
1057   } else {
1058     HeapWord* result = humongous_obj_allocate(word_size, context);
1059     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1060       collector_state()->set_initiate_conc_mark_if_possible(true);
1061     }
1062     return result;
1063   }
1064 
1065   ShouldNotReachHere();
1066 }
1067 
1068 class PostCompactionPrinterClosure: public HeapRegionClosure {
1069 private:
1070   G1HRPrinter* _hr_printer;
1071 public:
1072   bool doHeapRegion(HeapRegion* hr) {
1073     assert(!hr->is_young(), "not expecting to find young regions");
1074     _hr_printer->post_compaction(hr);
1075     return false;
1076   }
1077 
1078   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1079     : _hr_printer(hr_printer) { }
1080 };
1081 
1082 void G1CollectedHeap::print_hrm_post_compaction() {
1083   if (_hr_printer.is_active()) {
1084     PostCompactionPrinterClosure cl(hr_printer());
1085     heap_region_iterate(&cl);
1086   }
1087 
1088 }
1089 
1090 void G1CollectedHeap::abort_concurrent_cycle() {
1091   // Note: When we have a more flexible GC logging framework that
1092   // allows us to add optional attributes to a GC log record we
1093   // could consider timing and reporting how long we wait in the
1094   // following two methods.
1095   wait_while_free_regions_coming();
1096   // If we start the compaction before the CM threads finish
1097   // scanning the root regions we might trip them over as we'll
1098   // be moving objects / updating references. So let's wait until
1099   // they are done. By telling them to abort, they should complete
1100   // early.
1101   _cm->root_regions()->abort();
1102   _cm->root_regions()->wait_until_scan_finished();
1103   append_secondary_free_list_if_not_empty_with_lock();
1104 
1105   // Disable discovery and empty the discovered lists
1106   // for the CM ref processor.
1107   ref_processor_cm()->disable_discovery();
1108   ref_processor_cm()->abandon_partial_discovery();
1109   ref_processor_cm()->verify_no_references_recorded();
1110 
1111   // Abandon current iterations of concurrent marking and concurrent
1112   // refinement, if any are in progress.
1113   concurrent_mark()->abort();
1114 }
1115 
1116 void G1CollectedHeap::prepare_heap_for_full_collection() {
1117   // Make sure we'll choose a new allocation region afterwards.
1118   _allocator->release_mutator_alloc_region();
1119   _allocator->abandon_gc_alloc_regions();
1120   g1_rem_set()->cleanupHRRS();
1121 
1122   // We may have added regions to the current incremental collection
1123   // set between the last GC or pause and now. We need to clear the
1124   // incremental collection set and then start rebuilding it afresh
1125   // after this full GC.
1126   abandon_collection_set(collection_set());
1127 
1128   tear_down_region_sets(false /* free_list_only */);
1129   collector_state()->set_gcs_are_young(true);
1130 }
1131 
1132 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1133   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1134   assert(used() == recalculate_used(), "Should be equal");
1135   _verifier->verify_region_sets_optional();
1136   _verifier->verify_before_gc();
1137   _verifier->check_bitmaps("Full GC Start");
1138 }
1139 
1140 void G1CollectedHeap::prepare_heap_for_mutators() {
1141   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1142   ClassLoaderDataGraph::purge();
1143   MetaspaceAux::verify_metrics();
1144 
1145   // Prepare heap for normal collections.
1146   assert(num_free_regions() == 0, "we should not have added any free regions");
1147   rebuild_region_sets(false /* free_list_only */);
1148   abort_refinement();
1149   resize_if_necessary_after_full_collection();
1150 
1151   // Rebuild the strong code root lists for each region
1152   rebuild_strong_code_roots();
1153 
1154   // Start a new incremental collection set for the next pause
1155   start_new_collection_set();
1156 
1157   _allocator->init_mutator_alloc_region();
1158 
1159   // Post collection state updates.
1160   MetaspaceGC::compute_new_size();
1161 }
1162 
1163 void G1CollectedHeap::abort_refinement() {
1164   if (_hot_card_cache->use_cache()) {
1165     _hot_card_cache->reset_hot_cache();
1166   }
1167 
1168   // Discard all remembered set updates.
1169   JavaThread::dirty_card_queue_set().abandon_logs();
1170   assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1171 }
1172 
1173 void G1CollectedHeap::verify_after_full_collection() {
1174   check_gc_time_stamps();
1175   _hrm.verify_optional();
1176   _verifier->verify_region_sets_optional();
1177   _verifier->verify_after_gc();
1178   // Clear the previous marking bitmap, if needed for bitmap verification.
1179   // Note we cannot do this when we clear the next marking bitmap in
1180   // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1181   // objects marked during a full GC against the previous bitmap.
1182   // But we need to clear it before calling check_bitmaps below since
1183   // the full GC has compacted objects and updated TAMS but not updated
1184   // the prev bitmap.
1185   if (G1VerifyBitmaps) {
1186     GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1187     _cm->clear_prev_bitmap(workers());
1188   }
1189   _verifier->check_bitmaps("Full GC End");
1190 
1191   // At this point there should be no regions in the
1192   // entire heap tagged as young.
1193   assert(check_young_list_empty(), "young list should be empty at this point");
1194 
1195   // Note: since we've just done a full GC, concurrent
1196   // marking is no longer active. Therefore we need not
1197   // re-enable reference discovery for the CM ref processor.
1198   // That will be done at the start of the next marking cycle.
1199   // We also know that the STW processor should no longer
1200   // discover any new references.
1201   assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1202   assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1203   ref_processor_stw()->verify_no_references_recorded();
1204   ref_processor_cm()->verify_no_references_recorded();
1205 }
1206 
1207 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1208   // Post collection logging.
1209   // We should do this after we potentially resize the heap so
1210   // that all the COMMIT / UNCOMMIT events are generated before
1211   // the compaction events.
1212   print_hrm_post_compaction();
1213   heap_transition->print();
1214   print_heap_after_gc();
1215   print_heap_regions();
1216 #ifdef TRACESPINNING
1217   ParallelTaskTerminator::print_termination_counts();
1218 #endif
1219 }
1220 
1221 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1222                                          bool clear_all_soft_refs) {
1223   assert_at_safepoint(true /* should_be_vm_thread */);
1224 
1225   if (GCLocker::check_active_before_gc()) {
1226     // Full GC was not completed.
1227     return false;
1228   }
1229 
1230   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1231       collector_policy()->should_clear_all_soft_refs();
1232 
1233   G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1234   GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1235 
1236   collector.prepare_collection();
1237   collector.collect();
1238   collector.complete_collection();
1239 
1240   // Full collection was successfully completed.
1241   return true;
1242 }
1243 
1244 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1245   // Currently, there is no facility in the do_full_collection(bool) API to notify
1246   // the caller that the collection did not succeed (e.g., because it was locked
1247   // out by the GC locker). So, right now, we'll ignore the return value.
1248   bool dummy = do_full_collection(true,                /* explicit_gc */
1249                                   clear_all_soft_refs);
1250 }
1251 
1252 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1253   // Capacity, free and used after the GC counted as full regions to
1254   // include the waste in the following calculations.
1255   const size_t capacity_after_gc = capacity();
1256   const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1257 
1258   // This is enforced in arguments.cpp.
1259   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1260          "otherwise the code below doesn't make sense");
1261 
1262   // We don't have floating point command-line arguments
1263   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1264   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1265   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1266   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1267 
1268   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1269   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1270 
1271   // We have to be careful here as these two calculations can overflow
1272   // 32-bit size_t's.
1273   double used_after_gc_d = (double) used_after_gc;
1274   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1275   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1276 
1277   // Let's make sure that they are both under the max heap size, which
1278   // by default will make them fit into a size_t.
1279   double desired_capacity_upper_bound = (double) max_heap_size;
1280   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1281                                     desired_capacity_upper_bound);
1282   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1283                                     desired_capacity_upper_bound);
1284 
1285   // We can now safely turn them into size_t's.
1286   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1287   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1288 
1289   // This assert only makes sense here, before we adjust them
1290   // with respect to the min and max heap size.
1291   assert(minimum_desired_capacity <= maximum_desired_capacity,
1292          "minimum_desired_capacity = " SIZE_FORMAT ", "
1293          "maximum_desired_capacity = " SIZE_FORMAT,
1294          minimum_desired_capacity, maximum_desired_capacity);
1295 
1296   // Should not be greater than the heap max size. No need to adjust
1297   // it with respect to the heap min size as it's a lower bound (i.e.,
1298   // we'll try to make the capacity larger than it, not smaller).
1299   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1300   // Should not be less than the heap min size. No need to adjust it
1301   // with respect to the heap max size as it's an upper bound (i.e.,
1302   // we'll try to make the capacity smaller than it, not greater).
1303   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1304 
1305   if (capacity_after_gc < minimum_desired_capacity) {
1306     // Don't expand unless it's significant
1307     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1308 
1309     log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1310                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1311                               "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1312                               capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1313 
1314     expand(expand_bytes, _workers);
1315 
1316     // No expansion, now see if we want to shrink
1317   } else if (capacity_after_gc > maximum_desired_capacity) {
1318     // Capacity too large, compute shrinking size
1319     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1320 
1321     log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1322                               "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1323                               "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1324                               capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1325 
1326     shrink(shrink_bytes);
1327   }
1328 }
1329 
1330 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1331                                                             AllocationContext_t context,
1332                                                             bool do_gc,
1333                                                             bool clear_all_soft_refs,
1334                                                             bool expect_null_mutator_alloc_region,
1335                                                             bool* gc_succeeded) {
1336   *gc_succeeded = true;
1337   // Let's attempt the allocation first.
1338   HeapWord* result =
1339     attempt_allocation_at_safepoint(word_size,
1340                                     context,
1341                                     expect_null_mutator_alloc_region);
1342   if (result != NULL) {
1343     assert(*gc_succeeded, "sanity");
1344     return result;
1345   }
1346 
1347   // In a G1 heap, we're supposed to keep allocation from failing by
1348   // incremental pauses.  Therefore, at least for now, we'll favor
1349   // expansion over collection.  (This might change in the future if we can
1350   // do something smarter than full collection to satisfy a failed alloc.)
1351   result = expand_and_allocate(word_size, context);
1352   if (result != NULL) {
1353     assert(*gc_succeeded, "sanity");
1354     return result;
1355   }
1356 
1357   if (do_gc) {
1358     // Expansion didn't work, we'll try to do a Full GC.
1359     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1360                                        clear_all_soft_refs);
1361   }
1362 
1363   return NULL;
1364 }
1365 
1366 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1367                                                      AllocationContext_t context,
1368                                                      bool* succeeded) {
1369   assert_at_safepoint(true /* should_be_vm_thread */);
1370 
1371   // Attempts to allocate followed by Full GC.
1372   HeapWord* result =
1373     satisfy_failed_allocation_helper(word_size,
1374                                      context,
1375                                      true,  /* do_gc */
1376                                      false, /* clear_all_soft_refs */
1377                                      false, /* expect_null_mutator_alloc_region */
1378                                      succeeded);
1379 
1380   if (result != NULL || !*succeeded) {
1381     return result;
1382   }
1383 
1384   // Attempts to allocate followed by Full GC that will collect all soft references.
1385   result = satisfy_failed_allocation_helper(word_size,
1386                                             context,
1387                                             true, /* do_gc */
1388                                             true, /* clear_all_soft_refs */
1389                                             true, /* expect_null_mutator_alloc_region */
1390                                             succeeded);
1391 
1392   if (result != NULL || !*succeeded) {
1393     return result;
1394   }
1395 
1396   // Attempts to allocate, no GC
1397   result = satisfy_failed_allocation_helper(word_size,
1398                                             context,
1399                                             false, /* do_gc */
1400                                             false, /* clear_all_soft_refs */
1401                                             true,  /* expect_null_mutator_alloc_region */
1402                                             succeeded);
1403 
1404   if (result != NULL) {
1405     assert(*succeeded, "sanity");
1406     return result;
1407   }
1408 
1409   assert(!collector_policy()->should_clear_all_soft_refs(),
1410          "Flag should have been handled and cleared prior to this point");
1411 
1412   // What else?  We might try synchronous finalization later.  If the total
1413   // space available is large enough for the allocation, then a more
1414   // complete compaction phase than we've tried so far might be
1415   // appropriate.
1416   assert(*succeeded, "sanity");
1417   return NULL;
1418 }
1419 
1420 // Attempting to expand the heap sufficiently
1421 // to support an allocation of the given "word_size".  If
1422 // successful, perform the allocation and return the address of the
1423 // allocated block, or else "NULL".
1424 
1425 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1426   assert_at_safepoint(true /* should_be_vm_thread */);
1427 
1428   _verifier->verify_region_sets_optional();
1429 
1430   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1431   log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1432                             word_size * HeapWordSize);
1433 
1434 
1435   if (expand(expand_bytes, _workers)) {
1436     _hrm.verify_optional();
1437     _verifier->verify_region_sets_optional();
1438     return attempt_allocation_at_safepoint(word_size,
1439                                            context,
1440                                            false /* expect_null_mutator_alloc_region */);
1441   }
1442   return NULL;
1443 }
1444 
1445 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1446   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1447   aligned_expand_bytes = align_up(aligned_expand_bytes,
1448                                        HeapRegion::GrainBytes);
1449 
1450   log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1451                             expand_bytes, aligned_expand_bytes);
1452 
1453   if (is_maximal_no_gc()) {
1454     log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1455     return false;
1456   }
1457 
1458   double expand_heap_start_time_sec = os::elapsedTime();
1459   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1460   assert(regions_to_expand > 0, "Must expand by at least one region");
1461 
1462   uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1463   if (expand_time_ms != NULL) {
1464     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1465   }
1466 
1467   if (expanded_by > 0) {
1468     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1469     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1470     g1_policy()->record_new_heap_size(num_regions());
1471   } else {
1472     log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1473 
1474     // The expansion of the virtual storage space was unsuccessful.
1475     // Let's see if it was because we ran out of swap.
1476     if (G1ExitOnExpansionFailure &&
1477         _hrm.available() >= regions_to_expand) {
1478       // We had head room...
1479       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1480     }
1481   }
1482   return regions_to_expand > 0;
1483 }
1484 
1485 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1486   size_t aligned_shrink_bytes =
1487     ReservedSpace::page_align_size_down(shrink_bytes);
1488   aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1489                                          HeapRegion::GrainBytes);
1490   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1491 
1492   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1493   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1494 
1495 
1496   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",
1497                             shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1498   if (num_regions_removed > 0) {
1499     g1_policy()->record_new_heap_size(num_regions());
1500   } else {
1501     log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1502   }
1503 }
1504 
1505 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1506   _verifier->verify_region_sets_optional();
1507 
1508   // We should only reach here at the end of a Full GC which means we
1509   // should not not be holding to any GC alloc regions. The method
1510   // below will make sure of that and do any remaining clean up.
1511   _allocator->abandon_gc_alloc_regions();
1512 
1513   // Instead of tearing down / rebuilding the free lists here, we
1514   // could instead use the remove_all_pending() method on free_list to
1515   // remove only the ones that we need to remove.
1516   tear_down_region_sets(true /* free_list_only */);
1517   shrink_helper(shrink_bytes);
1518   rebuild_region_sets(true /* free_list_only */);
1519 
1520   _hrm.verify_optional();
1521   _verifier->verify_region_sets_optional();
1522 }
1523 
1524 // Public methods.
1525 
1526 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1527   CollectedHeap(),
1528   _young_gen_sampling_thread(NULL),
1529   _collector_policy(collector_policy),
1530   _memory_manager("G1 Young Generation", "end of minor GC"),
1531   _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1532   _eden_pool(NULL),
1533   _survivor_pool(NULL),
1534   _old_pool(NULL),
1535   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1536   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1537   _g1_policy(create_g1_policy(_gc_timer_stw)),
1538   _collection_set(this, _g1_policy),
1539   _dirty_card_queue_set(false),
1540   _is_alive_closure_cm(this),
1541   _is_alive_closure_stw(this),
1542   _ref_processor_cm(NULL),
1543   _ref_processor_stw(NULL),
1544   _bot(NULL),
1545   _hot_card_cache(NULL),
1546   _g1_rem_set(NULL),
1547   _cr(NULL),
1548   _g1mm(NULL),
1549   _preserved_marks_set(true /* in_c_heap */),
1550   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1551   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1552   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1553   _humongous_reclaim_candidates(),
1554   _has_humongous_reclaim_candidates(false),
1555   _archive_allocator(NULL),
1556   _free_regions_coming(false),
1557   _gc_time_stamp(0),
1558   _summary_bytes_used(0),
1559   _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1560   _old_evac_stats("Old", OldPLABSize, PLABWeight),
1561   _expand_heap_after_alloc_failure(true),
1562   _old_marking_cycles_started(0),
1563   _old_marking_cycles_completed(0),
1564   _in_cset_fast_test() {
1565 
1566   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1567                           /* are_GC_task_threads */true,
1568                           /* are_ConcurrentGC_threads */false);
1569   _workers->initialize_workers();
1570   _verifier = new G1HeapVerifier(this);
1571 
1572   _allocator = G1Allocator::create_allocator(this);
1573 
1574   _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1575 
1576   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1577 
1578   // Override the default _filler_array_max_size so that no humongous filler
1579   // objects are created.
1580   _filler_array_max_size = _humongous_object_threshold_in_words;
1581 
1582   uint n_queues = ParallelGCThreads;
1583   _task_queues = new RefToScanQueueSet(n_queues);
1584 
1585   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1586 
1587   for (uint i = 0; i < n_queues; i++) {
1588     RefToScanQueue* q = new RefToScanQueue();
1589     q->initialize();
1590     _task_queues->register_queue(i, q);
1591     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1592   }
1593 
1594   // Initialize the G1EvacuationFailureALot counters and flags.
1595   NOT_PRODUCT(reset_evacuation_should_fail();)
1596 
1597   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1598 }
1599 
1600 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1601                                                                  size_t size,
1602                                                                  size_t translation_factor) {
1603   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1604   // Allocate a new reserved space, preferring to use large pages.
1605   ReservedSpace rs(size, preferred_page_size);
1606   G1RegionToSpaceMapper* result  =
1607     G1RegionToSpaceMapper::create_mapper(rs,
1608                                          size,
1609                                          rs.alignment(),
1610                                          HeapRegion::GrainBytes,
1611                                          translation_factor,
1612                                          mtGC);
1613 
1614   os::trace_page_sizes_for_requested_size(description,
1615                                           size,
1616                                           preferred_page_size,
1617                                           rs.alignment(),
1618                                           rs.base(),
1619                                           rs.size());
1620 
1621   return result;
1622 }
1623 
1624 jint G1CollectedHeap::initialize_concurrent_refinement() {
1625   jint ecode = JNI_OK;
1626   _cr = G1ConcurrentRefine::create(&ecode);
1627   return ecode;
1628 }
1629 
1630 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1631   _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1632   if (_young_gen_sampling_thread->osthread() == NULL) {
1633     vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1634     return JNI_ENOMEM;
1635   }
1636   return JNI_OK;
1637 }
1638 
1639 jint G1CollectedHeap::initialize() {
1640   CollectedHeap::pre_initialize();
1641   os::enable_vtime();
1642 
1643   // Necessary to satisfy locking discipline assertions.
1644 
1645   MutexLocker x(Heap_lock);
1646 
1647   // While there are no constraints in the GC code that HeapWordSize
1648   // be any particular value, there are multiple other areas in the
1649   // system which believe this to be true (e.g. oop->object_size in some
1650   // cases incorrectly returns the size in wordSize units rather than
1651   // HeapWordSize).
1652   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1653 
1654   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1655   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1656   size_t heap_alignment = collector_policy()->heap_alignment();
1657 
1658   // Ensure that the sizes are properly aligned.
1659   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1660   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1661   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1662 
1663   // Reserve the maximum.
1664 
1665   // When compressed oops are enabled, the preferred heap base
1666   // is calculated by subtracting the requested size from the
1667   // 32Gb boundary and using the result as the base address for
1668   // heap reservation. If the requested size is not aligned to
1669   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1670   // into the ReservedHeapSpace constructor) then the actual
1671   // base of the reserved heap may end up differing from the
1672   // address that was requested (i.e. the preferred heap base).
1673   // If this happens then we could end up using a non-optimal
1674   // compressed oops mode.
1675 
1676   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1677                                                  heap_alignment);
1678 
1679   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1680 
1681   // Create the barrier set for the entire reserved region.
1682   G1SATBCardTableLoggingModRefBS* bs
1683     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1684   bs->initialize();
1685   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1686   set_barrier_set(bs);
1687 
1688   // Create the hot card cache.
1689   _hot_card_cache = new G1HotCardCache(this);
1690 
1691   // Carve out the G1 part of the heap.
1692   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1693   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1694   G1RegionToSpaceMapper* heap_storage =
1695     G1RegionToSpaceMapper::create_mapper(g1_rs,
1696                                          g1_rs.size(),
1697                                          page_size,
1698                                          HeapRegion::GrainBytes,
1699                                          1,
1700                                          mtJavaHeap);
1701   os::trace_page_sizes("Heap",
1702                        collector_policy()->min_heap_byte_size(),
1703                        max_byte_size,
1704                        page_size,
1705                        heap_rs.base(),
1706                        heap_rs.size());
1707   heap_storage->set_mapping_changed_listener(&_listener);
1708 
1709   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1710   G1RegionToSpaceMapper* bot_storage =
1711     create_aux_memory_mapper("Block Offset Table",
1712                              G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1713                              G1BlockOffsetTable::heap_map_factor());
1714 
1715   G1RegionToSpaceMapper* cardtable_storage =
1716     create_aux_memory_mapper("Card Table",
1717                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1718                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1719 
1720   G1RegionToSpaceMapper* card_counts_storage =
1721     create_aux_memory_mapper("Card Counts Table",
1722                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1723                              G1CardCounts::heap_map_factor());
1724 
1725   size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1726   G1RegionToSpaceMapper* prev_bitmap_storage =
1727     create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1728   G1RegionToSpaceMapper* next_bitmap_storage =
1729     create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1730 
1731   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1732   g1_barrier_set()->initialize(cardtable_storage);
1733   // Do later initialization work for concurrent refinement.
1734   _hot_card_cache->initialize(card_counts_storage);
1735 
1736   // 6843694 - ensure that the maximum region index can fit
1737   // in the remembered set structures.
1738   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1739   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1740 
1741   // Also create a G1 rem set.
1742   _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1743   _g1_rem_set->initialize(max_capacity(), max_regions());
1744 
1745   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1746   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1747   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1748             "too many cards per region");
1749 
1750   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1751 
1752   _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1753 
1754   {
1755     HeapWord* start = _hrm.reserved().start();
1756     HeapWord* end = _hrm.reserved().end();
1757     size_t granularity = HeapRegion::GrainBytes;
1758 
1759     _in_cset_fast_test.initialize(start, end, granularity);
1760     _humongous_reclaim_candidates.initialize(start, end, granularity);
1761   }
1762 
1763   // Create the G1ConcurrentMark data structure and thread.
1764   // (Must do this late, so that "max_regions" is defined.)
1765   _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1766   if (_cm == NULL || !_cm->completed_initialization()) {
1767     vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1768     return JNI_ENOMEM;
1769   }
1770   _cmThread = _cm->cm_thread();
1771 
1772   // Now expand into the initial heap size.
1773   if (!expand(init_byte_size, _workers)) {
1774     vm_shutdown_during_initialization("Failed to allocate initial heap.");
1775     return JNI_ENOMEM;
1776   }
1777 
1778   // Perform any initialization actions delegated to the policy.
1779   g1_policy()->init(this, &_collection_set);
1780 
1781   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1782                                                SATB_Q_FL_lock,
1783                                                G1SATBProcessCompletedThreshold,
1784                                                Shared_SATB_Q_lock);
1785 
1786   jint ecode = initialize_concurrent_refinement();
1787   if (ecode != JNI_OK) {
1788     return ecode;
1789   }
1790 
1791   ecode = initialize_young_gen_sampling_thread();
1792   if (ecode != JNI_OK) {
1793     return ecode;
1794   }
1795 
1796   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1797                                                 DirtyCardQ_FL_lock,
1798                                                 (int)concurrent_refine()->yellow_zone(),
1799                                                 (int)concurrent_refine()->red_zone(),
1800                                                 Shared_DirtyCardQ_lock,
1801                                                 NULL,  // fl_owner
1802                                                 true); // init_free_ids
1803 
1804   dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1805                                     DirtyCardQ_FL_lock,
1806                                     -1, // never trigger processing
1807                                     -1, // no limit on length
1808                                     Shared_DirtyCardQ_lock,
1809                                     &JavaThread::dirty_card_queue_set());
1810 
1811   // Here we allocate the dummy HeapRegion that is required by the
1812   // G1AllocRegion class.
1813   HeapRegion* dummy_region = _hrm.get_dummy_region();
1814 
1815   // We'll re-use the same region whether the alloc region will
1816   // require BOT updates or not and, if it doesn't, then a non-young
1817   // region will complain that it cannot support allocations without
1818   // BOT updates. So we'll tag the dummy region as eden to avoid that.
1819   dummy_region->set_eden();
1820   // Make sure it's full.
1821   dummy_region->set_top(dummy_region->end());
1822   G1AllocRegion::setup(this, dummy_region);
1823 
1824   _allocator->init_mutator_alloc_region();
1825 
1826   // Do create of the monitoring and management support so that
1827   // values in the heap have been properly initialized.
1828   _g1mm = new G1MonitoringSupport(this);
1829 
1830   _eden_pool = new G1EdenPool(this);
1831   _survivor_pool = new G1SurvivorPool(this);
1832   _old_pool = new G1OldGenPool(this);
1833 
1834   _full_gc_memory_manager.add_pool(_eden_pool);
1835   _full_gc_memory_manager.add_pool(_survivor_pool);
1836   _full_gc_memory_manager.add_pool(_old_pool);
1837 
1838   _memory_manager.add_pool(_eden_pool);
1839   _memory_manager.add_pool(_survivor_pool);
1840 
1841   G1StringDedup::initialize();
1842 
1843   _preserved_marks_set.init(ParallelGCThreads);
1844 
1845   _collection_set.initialize(max_regions());
1846 
1847   return JNI_OK;
1848 }
1849 
1850 void G1CollectedHeap::stop() {
1851   // Stop all concurrent threads. We do this to make sure these threads
1852   // do not continue to execute and access resources (e.g. logging)
1853   // that are destroyed during shutdown.
1854   _cr->stop();
1855   _young_gen_sampling_thread->stop();
1856   _cmThread->stop();
1857   if (G1StringDedup::is_enabled()) {
1858     G1StringDedup::stop();
1859   }
1860 }
1861 
1862 void G1CollectedHeap::safepoint_synchronize_begin() {
1863   SuspendibleThreadSet::synchronize();
1864 }
1865 
1866 void G1CollectedHeap::safepoint_synchronize_end() {
1867   SuspendibleThreadSet::desynchronize();
1868 }
1869 
1870 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1871   return HeapRegion::max_region_size();
1872 }
1873 
1874 void G1CollectedHeap::post_initialize() {
1875   ref_processing_init();
1876 }
1877 
1878 void G1CollectedHeap::ref_processing_init() {
1879   // Reference processing in G1 currently works as follows:
1880   //
1881   // * There are two reference processor instances. One is
1882   //   used to record and process discovered references
1883   //   during concurrent marking; the other is used to
1884   //   record and process references during STW pauses
1885   //   (both full and incremental).
1886   // * Both ref processors need to 'span' the entire heap as
1887   //   the regions in the collection set may be dotted around.
1888   //
1889   // * For the concurrent marking ref processor:
1890   //   * Reference discovery is enabled at initial marking.
1891   //   * Reference discovery is disabled and the discovered
1892   //     references processed etc during remarking.
1893   //   * Reference discovery is MT (see below).
1894   //   * Reference discovery requires a barrier (see below).
1895   //   * Reference processing may or may not be MT
1896   //     (depending on the value of ParallelRefProcEnabled
1897   //     and ParallelGCThreads).
1898   //   * A full GC disables reference discovery by the CM
1899   //     ref processor and abandons any entries on it's
1900   //     discovered lists.
1901   //
1902   // * For the STW processor:
1903   //   * Non MT discovery is enabled at the start of a full GC.
1904   //   * Processing and enqueueing during a full GC is non-MT.
1905   //   * During a full GC, references are processed after marking.
1906   //
1907   //   * Discovery (may or may not be MT) is enabled at the start
1908   //     of an incremental evacuation pause.
1909   //   * References are processed near the end of a STW evacuation pause.
1910   //   * For both types of GC:
1911   //     * Discovery is atomic - i.e. not concurrent.
1912   //     * Reference discovery will not need a barrier.
1913 
1914   MemRegion mr = reserved_region();
1915 
1916   bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1917 
1918   // Concurrent Mark ref processor
1919   _ref_processor_cm =
1920     new ReferenceProcessor(mr,    // span
1921                            mt_processing,
1922                                 // mt processing
1923                            ParallelGCThreads,
1924                                 // degree of mt processing
1925                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1926                                 // mt discovery
1927                            MAX2(ParallelGCThreads, ConcGCThreads),
1928                                 // degree of mt discovery
1929                            false,
1930                                 // Reference discovery is not atomic
1931                            &_is_alive_closure_cm);
1932                                 // is alive closure
1933                                 // (for efficiency/performance)
1934 
1935   // STW ref processor
1936   _ref_processor_stw =
1937     new ReferenceProcessor(mr,    // span
1938                            mt_processing,
1939                                 // mt processing
1940                            ParallelGCThreads,
1941                                 // degree of mt processing
1942                            (ParallelGCThreads > 1),
1943                                 // mt discovery
1944                            ParallelGCThreads,
1945                                 // degree of mt discovery
1946                            true,
1947                                 // Reference discovery is atomic
1948                            &_is_alive_closure_stw);
1949                                 // is alive closure
1950                                 // (for efficiency/performance)
1951 }
1952 
1953 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1954   return _collector_policy;
1955 }
1956 
1957 size_t G1CollectedHeap::capacity() const {
1958   return _hrm.length() * HeapRegion::GrainBytes;
1959 }
1960 
1961 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1962   return _hrm.total_free_bytes();
1963 }
1964 
1965 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1966   hr->reset_gc_time_stamp();
1967 }
1968 
1969 #ifndef PRODUCT
1970 
1971 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1972 private:
1973   unsigned _gc_time_stamp;
1974   bool _failures;
1975 
1976 public:
1977   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1978     _gc_time_stamp(gc_time_stamp), _failures(false) { }
1979 
1980   virtual bool doHeapRegion(HeapRegion* hr) {
1981     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1982     if (_gc_time_stamp != region_gc_time_stamp) {
1983       log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1984                             region_gc_time_stamp, _gc_time_stamp);
1985       _failures = true;
1986     }
1987     return false;
1988   }
1989 
1990   bool failures() { return _failures; }
1991 };
1992 
1993 void G1CollectedHeap::check_gc_time_stamps() {
1994   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1995   heap_region_iterate(&cl);
1996   guarantee(!cl.failures(), "all GC time stamps should have been reset");
1997 }
1998 #endif // PRODUCT
1999 
2000 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2001   _hot_card_cache->drain(cl, worker_i);
2002 }
2003 
2004 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2005   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2006   size_t n_completed_buffers = 0;
2007   while (dcqs.apply_closure_during_gc(cl, worker_i)) {
2008     n_completed_buffers++;
2009   }
2010   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2011   dcqs.clear_n_completed_buffers();
2012   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2013 }
2014 
2015 // Computes the sum of the storage used by the various regions.
2016 size_t G1CollectedHeap::used() const {
2017   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2018   if (_archive_allocator != NULL) {
2019     result += _archive_allocator->used();
2020   }
2021   return result;
2022 }
2023 
2024 size_t G1CollectedHeap::used_unlocked() const {
2025   return _summary_bytes_used;
2026 }
2027 
2028 class SumUsedClosure: public HeapRegionClosure {
2029   size_t _used;
2030 public:
2031   SumUsedClosure() : _used(0) {}
2032   bool doHeapRegion(HeapRegion* r) {
2033     _used += r->used();
2034     return false;
2035   }
2036   size_t result() { return _used; }
2037 };
2038 
2039 size_t G1CollectedHeap::recalculate_used() const {
2040   double recalculate_used_start = os::elapsedTime();
2041 
2042   SumUsedClosure blk;
2043   heap_region_iterate(&blk);
2044 
2045   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2046   return blk.result();
2047 }
2048 
2049 bool  G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2050   switch (cause) {
2051     case GCCause::_java_lang_system_gc:                 return ExplicitGCInvokesConcurrent;
2052     case GCCause::_dcmd_gc_run:                         return ExplicitGCInvokesConcurrent;
2053     case GCCause::_update_allocation_context_stats_inc: return true;
2054     case GCCause::_wb_conc_mark:                        return true;
2055     default :                                           return false;
2056   }
2057 }
2058 
2059 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2060   switch (cause) {
2061     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2062     case GCCause::_g1_humongous_allocation: return true;
2063     default:                                return is_user_requested_concurrent_full_gc(cause);
2064   }
2065 }
2066 
2067 #ifndef PRODUCT
2068 void G1CollectedHeap::allocate_dummy_regions() {
2069   // Let's fill up most of the region
2070   size_t word_size = HeapRegion::GrainWords - 1024;
2071   // And as a result the region we'll allocate will be humongous.
2072   guarantee(is_humongous(word_size), "sanity");
2073 
2074   // _filler_array_max_size is set to humongous object threshold
2075   // but temporarily change it to use CollectedHeap::fill_with_object().
2076   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2077 
2078   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2079     // Let's use the existing mechanism for the allocation
2080     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2081                                                  AllocationContext::system());
2082     if (dummy_obj != NULL) {
2083       MemRegion mr(dummy_obj, word_size);
2084       CollectedHeap::fill_with_object(mr);
2085     } else {
2086       // If we can't allocate once, we probably cannot allocate
2087       // again. Let's get out of the loop.
2088       break;
2089     }
2090   }
2091 }
2092 #endif // !PRODUCT
2093 
2094 void G1CollectedHeap::increment_old_marking_cycles_started() {
2095   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2096          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2097          "Wrong marking cycle count (started: %d, completed: %d)",
2098          _old_marking_cycles_started, _old_marking_cycles_completed);
2099 
2100   _old_marking_cycles_started++;
2101 }
2102 
2103 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2104   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2105 
2106   // We assume that if concurrent == true, then the caller is a
2107   // concurrent thread that was joined the Suspendible Thread
2108   // Set. If there's ever a cheap way to check this, we should add an
2109   // assert here.
2110 
2111   // Given that this method is called at the end of a Full GC or of a
2112   // concurrent cycle, and those can be nested (i.e., a Full GC can
2113   // interrupt a concurrent cycle), the number of full collections
2114   // completed should be either one (in the case where there was no
2115   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2116   // behind the number of full collections started.
2117 
2118   // This is the case for the inner caller, i.e. a Full GC.
2119   assert(concurrent ||
2120          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2121          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2122          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2123          "is inconsistent with _old_marking_cycles_completed = %u",
2124          _old_marking_cycles_started, _old_marking_cycles_completed);
2125 
2126   // This is the case for the outer caller, i.e. the concurrent cycle.
2127   assert(!concurrent ||
2128          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2129          "for outer caller (concurrent cycle): "
2130          "_old_marking_cycles_started = %u "
2131          "is inconsistent with _old_marking_cycles_completed = %u",
2132          _old_marking_cycles_started, _old_marking_cycles_completed);
2133 
2134   _old_marking_cycles_completed += 1;
2135 
2136   // We need to clear the "in_progress" flag in the CM thread before
2137   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2138   // is set) so that if a waiter requests another System.gc() it doesn't
2139   // incorrectly see that a marking cycle is still in progress.
2140   if (concurrent) {
2141     _cmThread->set_idle();
2142   }
2143 
2144   // This notify_all() will ensure that a thread that called
2145   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2146   // and it's waiting for a full GC to finish will be woken up. It is
2147   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2148   FullGCCount_lock->notify_all();
2149 }
2150 
2151 void G1CollectedHeap::collect(GCCause::Cause cause) {
2152   assert_heap_not_locked();
2153 
2154   uint gc_count_before;
2155   uint old_marking_count_before;
2156   uint full_gc_count_before;
2157   bool retry_gc;
2158 
2159   do {
2160     retry_gc = false;
2161 
2162     {
2163       MutexLocker ml(Heap_lock);
2164 
2165       // Read the GC count while holding the Heap_lock
2166       gc_count_before = total_collections();
2167       full_gc_count_before = total_full_collections();
2168       old_marking_count_before = _old_marking_cycles_started;
2169     }
2170 
2171     if (should_do_concurrent_full_gc(cause)) {
2172       // Schedule an initial-mark evacuation pause that will start a
2173       // concurrent cycle. We're setting word_size to 0 which means that
2174       // we are not requesting a post-GC allocation.
2175       VM_G1IncCollectionPause op(gc_count_before,
2176                                  0,     /* word_size */
2177                                  true,  /* should_initiate_conc_mark */
2178                                  g1_policy()->max_pause_time_ms(),
2179                                  cause);
2180       op.set_allocation_context(AllocationContext::current());
2181 
2182       VMThread::execute(&op);
2183       if (!op.pause_succeeded()) {
2184         if (old_marking_count_before == _old_marking_cycles_started) {
2185           retry_gc = op.should_retry_gc();
2186         } else {
2187           // A Full GC happened while we were trying to schedule the
2188           // initial-mark GC. No point in starting a new cycle given
2189           // that the whole heap was collected anyway.
2190         }
2191 
2192         if (retry_gc) {
2193           if (GCLocker::is_active_and_needs_gc()) {
2194             GCLocker::stall_until_clear();
2195           }
2196         }
2197       }
2198     } else {
2199       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2200           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2201 
2202         // Schedule a standard evacuation pause. We're setting word_size
2203         // to 0 which means that we are not requesting a post-GC allocation.
2204         VM_G1IncCollectionPause op(gc_count_before,
2205                                    0,     /* word_size */
2206                                    false, /* should_initiate_conc_mark */
2207                                    g1_policy()->max_pause_time_ms(),
2208                                    cause);
2209         VMThread::execute(&op);
2210       } else {
2211         // Schedule a Full GC.
2212         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2213         VMThread::execute(&op);
2214       }
2215     }
2216   } while (retry_gc);
2217 }
2218 
2219 bool G1CollectedHeap::is_in(const void* p) const {
2220   if (_hrm.reserved().contains(p)) {
2221     // Given that we know that p is in the reserved space,
2222     // heap_region_containing() should successfully
2223     // return the containing region.
2224     HeapRegion* hr = heap_region_containing(p);
2225     return hr->is_in(p);
2226   } else {
2227     return false;
2228   }
2229 }
2230 
2231 #ifdef ASSERT
2232 bool G1CollectedHeap::is_in_exact(const void* p) const {
2233   bool contains = reserved_region().contains(p);
2234   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2235   if (contains && available) {
2236     return true;
2237   } else {
2238     return false;
2239   }
2240 }
2241 #endif
2242 
2243 // Iteration functions.
2244 
2245 // Iterates an ObjectClosure over all objects within a HeapRegion.
2246 
2247 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2248   ObjectClosure* _cl;
2249 public:
2250   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2251   bool doHeapRegion(HeapRegion* r) {
2252     if (!r->is_continues_humongous()) {
2253       r->object_iterate(_cl);
2254     }
2255     return false;
2256   }
2257 };
2258 
2259 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2260   IterateObjectClosureRegionClosure blk(cl);
2261   heap_region_iterate(&blk);
2262 }
2263 
2264 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2265   _hrm.iterate(cl);
2266 }
2267 
2268 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2269                                                                  HeapRegionClaimer *hrclaimer,
2270                                                                  uint worker_id) const {
2271   _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2272 }
2273 
2274 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2275                                                          HeapRegionClaimer *hrclaimer) const {
2276   _hrm.par_iterate(cl, hrclaimer, 0);
2277 }
2278 
2279 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2280   _collection_set.iterate(cl);
2281 }
2282 
2283 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2284   _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2285 }
2286 
2287 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2288   HeapRegion* hr = heap_region_containing(addr);
2289   return hr->block_start(addr);
2290 }
2291 
2292 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2293   HeapRegion* hr = heap_region_containing(addr);
2294   return hr->block_size(addr);
2295 }
2296 
2297 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2298   HeapRegion* hr = heap_region_containing(addr);
2299   return hr->block_is_obj(addr);
2300 }
2301 
2302 bool G1CollectedHeap::supports_tlab_allocation() const {
2303   return true;
2304 }
2305 
2306 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2307   return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2308 }
2309 
2310 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2311   return _eden.length() * HeapRegion::GrainBytes;
2312 }
2313 
2314 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2315 // must be equal to the humongous object limit.
2316 size_t G1CollectedHeap::max_tlab_size() const {
2317   return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2318 }
2319 
2320 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2321   AllocationContext_t context = AllocationContext::current();
2322   return _allocator->unsafe_max_tlab_alloc(context);
2323 }
2324 
2325 size_t G1CollectedHeap::max_capacity() const {
2326   return _hrm.reserved().byte_size();
2327 }
2328 
2329 jlong G1CollectedHeap::millis_since_last_gc() {
2330   // See the notes in GenCollectedHeap::millis_since_last_gc()
2331   // for more information about the implementation.
2332   jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2333     _g1_policy->collection_pause_end_millis();
2334   if (ret_val < 0) {
2335     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2336       ". returning zero instead.", ret_val);
2337     return 0;
2338   }
2339   return ret_val;
2340 }
2341 
2342 void G1CollectedHeap::prepare_for_verify() {
2343   _verifier->prepare_for_verify();
2344 }
2345 
2346 void G1CollectedHeap::verify(VerifyOption vo) {
2347   _verifier->verify(vo);
2348 }
2349 
2350 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2351   return true;
2352 }
2353 
2354 const char* const* G1CollectedHeap::concurrent_phases() const {
2355   return _cmThread->concurrent_phases();
2356 }
2357 
2358 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2359   return _cmThread->request_concurrent_phase(phase);
2360 }
2361 
2362 class PrintRegionClosure: public HeapRegionClosure {
2363   outputStream* _st;
2364 public:
2365   PrintRegionClosure(outputStream* st) : _st(st) {}
2366   bool doHeapRegion(HeapRegion* r) {
2367     r->print_on(_st);
2368     return false;
2369   }
2370 };
2371 
2372 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2373                                        const HeapRegion* hr,
2374                                        const VerifyOption vo) const {
2375   switch (vo) {
2376   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2377   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2378   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2379   default:                            ShouldNotReachHere();
2380   }
2381   return false; // keep some compilers happy
2382 }
2383 
2384 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2385                                        const VerifyOption vo) const {
2386   switch (vo) {
2387   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2388   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2389   case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2390   default:                            ShouldNotReachHere();
2391   }
2392   return false; // keep some compilers happy
2393 }
2394 
2395 void G1CollectedHeap::print_heap_regions() const {
2396   LogTarget(Trace, gc, heap, region) lt;
2397   if (lt.is_enabled()) {
2398     LogStream ls(lt);
2399     print_regions_on(&ls);
2400   }
2401 }
2402 
2403 void G1CollectedHeap::print_on(outputStream* st) const {
2404   st->print(" %-20s", "garbage-first heap");
2405   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2406             capacity()/K, used_unlocked()/K);
2407   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2408             p2i(_hrm.reserved().start()),
2409             p2i(_hrm.reserved().end()));
2410   st->cr();
2411   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2412   uint young_regions = young_regions_count();
2413   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2414             (size_t) young_regions * HeapRegion::GrainBytes / K);
2415   uint survivor_regions = survivor_regions_count();
2416   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2417             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2418   st->cr();
2419   MetaspaceAux::print_on(st);
2420 }
2421 
2422 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2423   st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2424                "HS=humongous(starts), HC=humongous(continues), "
2425                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2426                "AC=allocation context, "
2427                "TAMS=top-at-mark-start (previous, next)");
2428   PrintRegionClosure blk(st);
2429   heap_region_iterate(&blk);
2430 }
2431 
2432 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2433   print_on(st);
2434 
2435   // Print the per-region information.
2436   print_regions_on(st);
2437 }
2438 
2439 void G1CollectedHeap::print_on_error(outputStream* st) const {
2440   this->CollectedHeap::print_on_error(st);
2441 
2442   if (_cm != NULL) {
2443     st->cr();
2444     _cm->print_on_error(st);
2445   }
2446 }
2447 
2448 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2449   workers()->print_worker_threads_on(st);
2450   _cmThread->print_on(st);
2451   st->cr();
2452   _cm->print_worker_threads_on(st);
2453   _cr->print_threads_on(st);
2454   _young_gen_sampling_thread->print_on(st);
2455   if (G1StringDedup::is_enabled()) {
2456     G1StringDedup::print_worker_threads_on(st);
2457   }
2458 }
2459 
2460 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2461   workers()->threads_do(tc);
2462   tc->do_thread(_cmThread);
2463   _cm->threads_do(tc);
2464   _cr->threads_do(tc);
2465   tc->do_thread(_young_gen_sampling_thread);
2466   if (G1StringDedup::is_enabled()) {
2467     G1StringDedup::threads_do(tc);
2468   }
2469 }
2470 
2471 void G1CollectedHeap::print_tracing_info() const {
2472   g1_rem_set()->print_summary_info();
2473   concurrent_mark()->print_summary_info();
2474 }
2475 
2476 #ifndef PRODUCT
2477 // Helpful for debugging RSet issues.
2478 
2479 class PrintRSetsClosure : public HeapRegionClosure {
2480 private:
2481   const char* _msg;
2482   size_t _occupied_sum;
2483 
2484 public:
2485   bool doHeapRegion(HeapRegion* r) {
2486     HeapRegionRemSet* hrrs = r->rem_set();
2487     size_t occupied = hrrs->occupied();
2488     _occupied_sum += occupied;
2489 
2490     tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2491     if (occupied == 0) {
2492       tty->print_cr("  RSet is empty");
2493     } else {
2494       hrrs->print();
2495     }
2496     tty->print_cr("----------");
2497     return false;
2498   }
2499 
2500   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2501     tty->cr();
2502     tty->print_cr("========================================");
2503     tty->print_cr("%s", msg);
2504     tty->cr();
2505   }
2506 
2507   ~PrintRSetsClosure() {
2508     tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2509     tty->print_cr("========================================");
2510     tty->cr();
2511   }
2512 };
2513 
2514 void G1CollectedHeap::print_cset_rsets() {
2515   PrintRSetsClosure cl("Printing CSet RSets");
2516   collection_set_iterate(&cl);
2517 }
2518 
2519 void G1CollectedHeap::print_all_rsets() {
2520   PrintRSetsClosure cl("Printing All RSets");;
2521   heap_region_iterate(&cl);
2522 }
2523 #endif // PRODUCT
2524 
2525 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2526 
2527   size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2528   size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2529   size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2530 
2531   size_t eden_capacity_bytes =
2532     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2533 
2534   VirtualSpaceSummary heap_summary = create_heap_space_summary();
2535   return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2536                        eden_capacity_bytes, survivor_used_bytes, num_regions());
2537 }
2538 
2539 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2540   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2541                        stats->unused(), stats->used(), stats->region_end_waste(),
2542                        stats->regions_filled(), stats->direct_allocated(),
2543                        stats->failure_used(), stats->failure_waste());
2544 }
2545 
2546 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2547   const G1HeapSummary& heap_summary = create_g1_heap_summary();
2548   gc_tracer->report_gc_heap_summary(when, heap_summary);
2549 
2550   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2551   gc_tracer->report_metaspace_summary(when, metaspace_summary);
2552 }
2553 
2554 G1CollectedHeap* G1CollectedHeap::heap() {
2555   CollectedHeap* heap = Universe::heap();
2556   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2557   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2558   return (G1CollectedHeap*)heap;
2559 }
2560 
2561 void G1CollectedHeap::gc_prologue(bool full) {
2562   // always_do_update_barrier = false;
2563   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2564 
2565   // This summary needs to be printed before incrementing total collections.
2566   g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2567 
2568   // Update common counters.
2569   increment_total_collections(full /* full gc */);
2570   if (full) {
2571     increment_old_marking_cycles_started();
2572     reset_gc_time_stamp();
2573   } else {
2574     increment_gc_time_stamp();
2575   }
2576 
2577   // Fill TLAB's and such
2578   double start = os::elapsedTime();
2579   accumulate_statistics_all_tlabs();
2580   ensure_parsability(true);
2581   g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2582 }
2583 
2584 void G1CollectedHeap::gc_epilogue(bool full) {
2585   // Update common counters.
2586   if (full) {
2587     // Update the number of full collections that have been completed.
2588     increment_old_marking_cycles_completed(false /* concurrent */);
2589   }
2590 
2591   // We are at the end of the GC. Total collections has already been increased.
2592   g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2593 
2594   // FIXME: what is this about?
2595   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2596   // is set.
2597 #if COMPILER2_OR_JVMCI
2598   assert(DerivedPointerTable::is_empty(), "derived pointer present");
2599 #endif
2600   // always_do_update_barrier = true;
2601 
2602   double start = os::elapsedTime();
2603   resize_all_tlabs();
2604   g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2605 
2606   allocation_context_stats().update(full);
2607 
2608   MemoryService::track_memory_usage();
2609   // We have just completed a GC. Update the soft reference
2610   // policy with the new heap occupancy
2611   Universe::update_heap_info_at_gc();
2612 }
2613 
2614 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2615                                                uint gc_count_before,
2616                                                bool* succeeded,
2617                                                GCCause::Cause gc_cause) {
2618   assert_heap_not_locked_and_not_at_safepoint();
2619   VM_G1IncCollectionPause op(gc_count_before,
2620                              word_size,
2621                              false, /* should_initiate_conc_mark */
2622                              g1_policy()->max_pause_time_ms(),
2623                              gc_cause);
2624 
2625   op.set_allocation_context(AllocationContext::current());
2626   VMThread::execute(&op);
2627 
2628   HeapWord* result = op.result();
2629   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2630   assert(result == NULL || ret_succeeded,
2631          "the result should be NULL if the VM did not succeed");
2632   *succeeded = ret_succeeded;
2633 
2634   assert_heap_not_locked();
2635   return result;
2636 }
2637 
2638 void
2639 G1CollectedHeap::doConcurrentMark() {
2640   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2641   if (!_cmThread->in_progress()) {
2642     _cmThread->set_started();
2643     CGC_lock->notify();
2644   }
2645 }
2646 
2647 size_t G1CollectedHeap::pending_card_num() {
2648   size_t extra_cards = 0;
2649   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2650     DirtyCardQueue& dcq = curr->dirty_card_queue();
2651     extra_cards += dcq.size();
2652   }
2653   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2654   size_t buffer_size = dcqs.buffer_size();
2655   size_t buffer_num = dcqs.completed_buffers_num();
2656 
2657   return buffer_size * buffer_num + extra_cards;
2658 }
2659 
2660 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2661  private:
2662   size_t _total_humongous;
2663   size_t _candidate_humongous;
2664 
2665   DirtyCardQueue _dcq;
2666 
2667   // We don't nominate objects with many remembered set entries, on
2668   // the assumption that such objects are likely still live.
2669   bool is_remset_small(HeapRegion* region) const {
2670     HeapRegionRemSet* const rset = region->rem_set();
2671     return G1EagerReclaimHumongousObjectsWithStaleRefs
2672       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2673       : rset->is_empty();
2674   }
2675 
2676   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2677     assert(region->is_starts_humongous(), "Must start a humongous object");
2678 
2679     oop obj = oop(region->bottom());
2680 
2681     // Dead objects cannot be eager reclaim candidates. Due to class
2682     // unloading it is unsafe to query their classes so we return early.
2683     if (heap->is_obj_dead(obj, region)) {
2684       return false;
2685     }
2686 
2687     // Candidate selection must satisfy the following constraints
2688     // while concurrent marking is in progress:
2689     //
2690     // * In order to maintain SATB invariants, an object must not be
2691     // reclaimed if it was allocated before the start of marking and
2692     // has not had its references scanned.  Such an object must have
2693     // its references (including type metadata) scanned to ensure no
2694     // live objects are missed by the marking process.  Objects
2695     // allocated after the start of concurrent marking don't need to
2696     // be scanned.
2697     //
2698     // * An object must not be reclaimed if it is on the concurrent
2699     // mark stack.  Objects allocated after the start of concurrent
2700     // marking are never pushed on the mark stack.
2701     //
2702     // Nominating only objects allocated after the start of concurrent
2703     // marking is sufficient to meet both constraints.  This may miss
2704     // some objects that satisfy the constraints, but the marking data
2705     // structures don't support efficiently performing the needed
2706     // additional tests or scrubbing of the mark stack.
2707     //
2708     // However, we presently only nominate is_typeArray() objects.
2709     // A humongous object containing references induces remembered
2710     // set entries on other regions.  In order to reclaim such an
2711     // object, those remembered sets would need to be cleaned up.
2712     //
2713     // We also treat is_typeArray() objects specially, allowing them
2714     // to be reclaimed even if allocated before the start of
2715     // concurrent mark.  For this we rely on mark stack insertion to
2716     // exclude is_typeArray() objects, preventing reclaiming an object
2717     // that is in the mark stack.  We also rely on the metadata for
2718     // such objects to be built-in and so ensured to be kept live.
2719     // Frequent allocation and drop of large binary blobs is an
2720     // important use case for eager reclaim, and this special handling
2721     // may reduce needed headroom.
2722 
2723     return obj->is_typeArray() && is_remset_small(region);
2724   }
2725 
2726  public:
2727   RegisterHumongousWithInCSetFastTestClosure()
2728   : _total_humongous(0),
2729     _candidate_humongous(0),
2730     _dcq(&JavaThread::dirty_card_queue_set()) {
2731   }
2732 
2733   virtual bool doHeapRegion(HeapRegion* r) {
2734     if (!r->is_starts_humongous()) {
2735       return false;
2736     }
2737     G1CollectedHeap* g1h = G1CollectedHeap::heap();
2738 
2739     bool is_candidate = humongous_region_is_candidate(g1h, r);
2740     uint rindex = r->hrm_index();
2741     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2742     if (is_candidate) {
2743       _candidate_humongous++;
2744       g1h->register_humongous_region_with_cset(rindex);
2745       // Is_candidate already filters out humongous object with large remembered sets.
2746       // If we have a humongous object with a few remembered sets, we simply flush these
2747       // remembered set entries into the DCQS. That will result in automatic
2748       // re-evaluation of their remembered set entries during the following evacuation
2749       // phase.
2750       if (!r->rem_set()->is_empty()) {
2751         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2752                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2753         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2754         HeapRegionRemSetIterator hrrs(r->rem_set());
2755         size_t card_index;
2756         while (hrrs.has_next(card_index)) {
2757           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2758           // The remembered set might contain references to already freed
2759           // regions. Filter out such entries to avoid failing card table
2760           // verification.
2761           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2762             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2763               *card_ptr = CardTableModRefBS::dirty_card_val();
2764               _dcq.enqueue(card_ptr);
2765             }
2766           }
2767         }
2768         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2769                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2770                hrrs.n_yielded(), r->rem_set()->occupied());
2771         r->rem_set()->clear_locked();
2772       }
2773       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2774     }
2775     _total_humongous++;
2776 
2777     return false;
2778   }
2779 
2780   size_t total_humongous() const { return _total_humongous; }
2781   size_t candidate_humongous() const { return _candidate_humongous; }
2782 
2783   void flush_rem_set_entries() { _dcq.flush(); }
2784 };
2785 
2786 void G1CollectedHeap::register_humongous_regions_with_cset() {
2787   if (!G1EagerReclaimHumongousObjects) {
2788     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2789     return;
2790   }
2791   double time = os::elapsed_counter();
2792 
2793   // Collect reclaim candidate information and register candidates with cset.
2794   RegisterHumongousWithInCSetFastTestClosure cl;
2795   heap_region_iterate(&cl);
2796 
2797   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2798   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2799                                                                   cl.total_humongous(),
2800                                                                   cl.candidate_humongous());
2801   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2802 
2803   // Finally flush all remembered set entries to re-check into the global DCQS.
2804   cl.flush_rem_set_entries();
2805 }
2806 
2807 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2808   public:
2809     bool doHeapRegion(HeapRegion* hr) {
2810       if (!hr->is_archive() && !hr->is_continues_humongous()) {
2811         hr->verify_rem_set();
2812       }
2813       return false;
2814     }
2815 };
2816 
2817 uint G1CollectedHeap::num_task_queues() const {
2818   return _task_queues->size();
2819 }
2820 
2821 #if TASKQUEUE_STATS
2822 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2823   st->print_raw_cr("GC Task Stats");
2824   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2825   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2826 }
2827 
2828 void G1CollectedHeap::print_taskqueue_stats() const {
2829   if (!log_is_enabled(Trace, gc, task, stats)) {
2830     return;
2831   }
2832   Log(gc, task, stats) log;
2833   ResourceMark rm;
2834   LogStream ls(log.trace());
2835   outputStream* st = &ls;
2836 
2837   print_taskqueue_stats_hdr(st);
2838 
2839   TaskQueueStats totals;
2840   const uint n = num_task_queues();
2841   for (uint i = 0; i < n; ++i) {
2842     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2843     totals += task_queue(i)->stats;
2844   }
2845   st->print_raw("tot "); totals.print(st); st->cr();
2846 
2847   DEBUG_ONLY(totals.verify());
2848 }
2849 
2850 void G1CollectedHeap::reset_taskqueue_stats() {
2851   const uint n = num_task_queues();
2852   for (uint i = 0; i < n; ++i) {
2853     task_queue(i)->stats.reset();
2854   }
2855 }
2856 #endif // TASKQUEUE_STATS
2857 
2858 void G1CollectedHeap::wait_for_root_region_scanning() {
2859   double scan_wait_start = os::elapsedTime();
2860   // We have to wait until the CM threads finish scanning the
2861   // root regions as it's the only way to ensure that all the
2862   // objects on them have been correctly scanned before we start
2863   // moving them during the GC.
2864   bool waited = _cm->root_regions()->wait_until_scan_finished();
2865   double wait_time_ms = 0.0;
2866   if (waited) {
2867     double scan_wait_end = os::elapsedTime();
2868     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2869   }
2870   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2871 }
2872 
2873 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2874 private:
2875   G1HRPrinter* _hr_printer;
2876 public:
2877   G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2878 
2879   virtual bool doHeapRegion(HeapRegion* r) {
2880     _hr_printer->cset(r);
2881     return false;
2882   }
2883 };
2884 
2885 void G1CollectedHeap::start_new_collection_set() {
2886   collection_set()->start_incremental_building();
2887 
2888   clear_cset_fast_test();
2889 
2890   guarantee(_eden.length() == 0, "eden should have been cleared");
2891   g1_policy()->transfer_survivors_to_cset(survivor());
2892 }
2893 
2894 bool
2895 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2896   assert_at_safepoint(true /* should_be_vm_thread */);
2897   guarantee(!is_gc_active(), "collection is not reentrant");
2898 
2899   if (GCLocker::check_active_before_gc()) {
2900     return false;
2901   }
2902 
2903   _gc_timer_stw->register_gc_start();
2904 
2905   GCIdMark gc_id_mark;
2906   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2907 
2908   SvcGCMarker sgcm(SvcGCMarker::MINOR);
2909   ResourceMark rm;
2910 
2911   g1_policy()->note_gc_start();
2912 
2913   wait_for_root_region_scanning();
2914 
2915   print_heap_before_gc();
2916   print_heap_regions();
2917   trace_heap_before_gc(_gc_tracer_stw);
2918 
2919   _verifier->verify_region_sets_optional();
2920   _verifier->verify_dirty_young_regions();
2921 
2922   // We should not be doing initial mark unless the conc mark thread is running
2923   if (!_cmThread->should_terminate()) {
2924     // This call will decide whether this pause is an initial-mark
2925     // pause. If it is, during_initial_mark_pause() will return true
2926     // for the duration of this pause.
2927     g1_policy()->decide_on_conc_mark_initiation();
2928   }
2929 
2930   // We do not allow initial-mark to be piggy-backed on a mixed GC.
2931   assert(!collector_state()->during_initial_mark_pause() ||
2932           collector_state()->gcs_are_young(), "sanity");
2933 
2934   // We also do not allow mixed GCs during marking.
2935   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2936 
2937   // Record whether this pause is an initial mark. When the current
2938   // thread has completed its logging output and it's safe to signal
2939   // the CM thread, the flag's value in the policy has been reset.
2940   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2941 
2942   // Inner scope for scope based logging, timers, and stats collection
2943   {
2944     EvacuationInfo evacuation_info;
2945 
2946     if (collector_state()->during_initial_mark_pause()) {
2947       // We are about to start a marking cycle, so we increment the
2948       // full collection counter.
2949       increment_old_marking_cycles_started();
2950       _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2951     }
2952 
2953     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2954 
2955     GCTraceCPUTime tcpu;
2956 
2957     FormatBuffer<> gc_string("Pause ");
2958     if (collector_state()->during_initial_mark_pause()) {
2959       gc_string.append("Initial Mark");
2960     } else if (collector_state()->gcs_are_young()) {
2961       gc_string.append("Young");
2962     } else {
2963       gc_string.append("Mixed");
2964     }
2965     GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2966 
2967     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2968                                                                   workers()->active_workers(),
2969                                                                   Threads::number_of_non_daemon_threads());
2970     workers()->update_active_workers(active_workers);
2971     log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2972 
2973     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2974     TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2975 
2976     // If the secondary_free_list is not empty, append it to the
2977     // free_list. No need to wait for the cleanup operation to finish;
2978     // the region allocation code will check the secondary_free_list
2979     // and wait if necessary. If the G1StressConcRegionFreeing flag is
2980     // set, skip this step so that the region allocation code has to
2981     // get entries from the secondary_free_list.
2982     if (!G1StressConcRegionFreeing) {
2983       append_secondary_free_list_if_not_empty_with_lock();
2984     }
2985 
2986     G1HeapTransition heap_transition(this);
2987     size_t heap_used_bytes_before_gc = used();
2988 
2989     // Don't dynamically change the number of GC threads this early.  A value of
2990     // 0 is used to indicate serial work.  When parallel work is done,
2991     // it will be set.
2992 
2993     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2994       IsGCActiveMark x;
2995 
2996       gc_prologue(false);
2997 
2998       if (VerifyRememberedSets) {
2999         log_info(gc, verify)("[Verifying RemSets before GC]");
3000         VerifyRegionRemSetClosure v_cl;
3001         heap_region_iterate(&v_cl);
3002       }
3003 
3004       _verifier->verify_before_gc();
3005 
3006       _verifier->check_bitmaps("GC Start");
3007 
3008 #if COMPILER2_OR_JVMCI
3009       DerivedPointerTable::clear();
3010 #endif
3011 
3012       // Please see comment in g1CollectedHeap.hpp and
3013       // G1CollectedHeap::ref_processing_init() to see how
3014       // reference processing currently works in G1.
3015 
3016       // Enable discovery in the STW reference processor
3017       if (g1_policy()->should_process_references()) {
3018         ref_processor_stw()->enable_discovery();
3019       } else {
3020         ref_processor_stw()->disable_discovery();
3021       }
3022 
3023       {
3024         // We want to temporarily turn off discovery by the
3025         // CM ref processor, if necessary, and turn it back on
3026         // on again later if we do. Using a scoped
3027         // NoRefDiscovery object will do this.
3028         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3029 
3030         // Forget the current alloc region (we might even choose it to be part
3031         // of the collection set!).
3032         _allocator->release_mutator_alloc_region();
3033 
3034         // This timing is only used by the ergonomics to handle our pause target.
3035         // It is unclear why this should not include the full pause. We will
3036         // investigate this in CR 7178365.
3037         //
3038         // Preserving the old comment here if that helps the investigation:
3039         //
3040         // The elapsed time induced by the start time below deliberately elides
3041         // the possible verification above.
3042         double sample_start_time_sec = os::elapsedTime();
3043 
3044         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3045 
3046         if (collector_state()->during_initial_mark_pause()) {
3047           concurrent_mark()->checkpoint_roots_initial_pre();
3048         }
3049 
3050         g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3051 
3052         evacuation_info.set_collectionset_regions(collection_set()->region_length());
3053 
3054         // Make sure the remembered sets are up to date. This needs to be
3055         // done before register_humongous_regions_with_cset(), because the
3056         // remembered sets are used there to choose eager reclaim candidates.
3057         // If the remembered sets are not up to date we might miss some
3058         // entries that need to be handled.
3059         g1_rem_set()->cleanupHRRS();
3060 
3061         register_humongous_regions_with_cset();
3062 
3063         assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3064 
3065         // We call this after finalize_cset() to
3066         // ensure that the CSet has been finalized.
3067         _cm->verify_no_cset_oops();
3068 
3069         if (_hr_printer.is_active()) {
3070           G1PrintCollectionSetClosure cl(&_hr_printer);
3071           _collection_set.iterate(&cl);
3072         }
3073 
3074         // Initialize the GC alloc regions.
3075         _allocator->init_gc_alloc_regions(evacuation_info);
3076 
3077         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3078         pre_evacuate_collection_set();
3079 
3080         // Actually do the work...
3081         evacuate_collection_set(evacuation_info, &per_thread_states);
3082 
3083         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3084 
3085         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3086         free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3087 
3088         eagerly_reclaim_humongous_regions();
3089 
3090         record_obj_copy_mem_stats();
3091         _survivor_evac_stats.adjust_desired_plab_sz();
3092         _old_evac_stats.adjust_desired_plab_sz();
3093 
3094         double start = os::elapsedTime();
3095         start_new_collection_set();
3096         g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3097 
3098         if (evacuation_failed()) {
3099           set_used(recalculate_used());
3100           if (_archive_allocator != NULL) {
3101             _archive_allocator->clear_used();
3102           }
3103           for (uint i = 0; i < ParallelGCThreads; i++) {
3104             if (_evacuation_failed_info_array[i].has_failed()) {
3105               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3106             }
3107           }
3108         } else {
3109           // The "used" of the the collection set have already been subtracted
3110           // when they were freed.  Add in the bytes evacuated.
3111           increase_used(g1_policy()->bytes_copied_during_gc());
3112         }
3113 
3114         if (collector_state()->during_initial_mark_pause()) {
3115           // We have to do this before we notify the CM threads that
3116           // they can start working to make sure that all the
3117           // appropriate initialization is done on the CM object.
3118           concurrent_mark()->checkpoint_roots_initial_post();
3119           collector_state()->set_mark_in_progress(true);
3120           // Note that we don't actually trigger the CM thread at
3121           // this point. We do that later when we're sure that
3122           // the current thread has completed its logging output.
3123         }
3124 
3125         allocate_dummy_regions();
3126 
3127         _allocator->init_mutator_alloc_region();
3128 
3129         {
3130           size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3131           if (expand_bytes > 0) {
3132             size_t bytes_before = capacity();
3133             // No need for an ergo logging here,
3134             // expansion_amount() does this when it returns a value > 0.
3135             double expand_ms;
3136             if (!expand(expand_bytes, _workers, &expand_ms)) {
3137               // We failed to expand the heap. Cannot do anything about it.
3138             }
3139             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3140           }
3141         }
3142 
3143         // We redo the verification but now wrt to the new CSet which
3144         // has just got initialized after the previous CSet was freed.
3145         _cm->verify_no_cset_oops();
3146 
3147         // This timing is only used by the ergonomics to handle our pause target.
3148         // It is unclear why this should not include the full pause. We will
3149         // investigate this in CR 7178365.
3150         double sample_end_time_sec = os::elapsedTime();
3151         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3152         size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3153         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3154 
3155         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3156         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3157 
3158         if (VerifyRememberedSets) {
3159           log_info(gc, verify)("[Verifying RemSets after GC]");
3160           VerifyRegionRemSetClosure v_cl;
3161           heap_region_iterate(&v_cl);
3162         }
3163 
3164         _verifier->verify_after_gc();
3165         _verifier->check_bitmaps("GC End");
3166 
3167         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3168         ref_processor_stw()->verify_no_references_recorded();
3169 
3170         // CM reference discovery will be re-enabled if necessary.
3171       }
3172 
3173 #ifdef TRACESPINNING
3174       ParallelTaskTerminator::print_termination_counts();
3175 #endif
3176 
3177       gc_epilogue(false);
3178     }
3179 
3180     // Print the remainder of the GC log output.
3181     if (evacuation_failed()) {
3182       log_info(gc)("To-space exhausted");
3183     }
3184 
3185     g1_policy()->print_phases();
3186     heap_transition.print();
3187 
3188     // It is not yet to safe to tell the concurrent mark to
3189     // start as we have some optional output below. We don't want the
3190     // output from the concurrent mark thread interfering with this
3191     // logging output either.
3192 
3193     _hrm.verify_optional();
3194     _verifier->verify_region_sets_optional();
3195 
3196     TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3197     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3198 
3199     print_heap_after_gc();
3200     print_heap_regions();
3201     trace_heap_after_gc(_gc_tracer_stw);
3202 
3203     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3204     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3205     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3206     // before any GC notifications are raised.
3207     g1mm()->update_sizes();
3208 
3209     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3210     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3211     _gc_timer_stw->register_gc_end();
3212     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3213   }
3214   // It should now be safe to tell the concurrent mark thread to start
3215   // without its logging output interfering with the logging output
3216   // that came from the pause.
3217 
3218   if (should_start_conc_mark) {
3219     // CAUTION: after the doConcurrentMark() call below,
3220     // the concurrent marking thread(s) could be running
3221     // concurrently with us. Make sure that anything after
3222     // this point does not assume that we are the only GC thread
3223     // running. Note: of course, the actual marking work will
3224     // not start until the safepoint itself is released in
3225     // SuspendibleThreadSet::desynchronize().
3226     doConcurrentMark();
3227   }
3228 
3229   return true;
3230 }
3231 
3232 void G1CollectedHeap::remove_self_forwarding_pointers() {
3233   G1ParRemoveSelfForwardPtrsTask rsfp_task;
3234   workers()->run_task(&rsfp_task);
3235 }
3236 
3237 void G1CollectedHeap::restore_after_evac_failure() {
3238   double remove_self_forwards_start = os::elapsedTime();
3239 
3240   remove_self_forwarding_pointers();
3241   SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3242   _preserved_marks_set.restore(&task_executor);
3243 
3244   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3245 }
3246 
3247 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3248   if (!_evacuation_failed) {
3249     _evacuation_failed = true;
3250   }
3251 
3252   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3253   _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3254 }
3255 
3256 bool G1ParEvacuateFollowersClosure::offer_termination() {
3257   G1ParScanThreadState* const pss = par_scan_state();
3258   start_term_time();
3259   const bool res = terminator()->offer_termination();
3260   end_term_time();
3261   return res;
3262 }
3263 
3264 void G1ParEvacuateFollowersClosure::do_void() {
3265   G1ParScanThreadState* const pss = par_scan_state();
3266   pss->trim_queue();
3267   do {
3268     pss->steal_and_trim_queue(queues());
3269   } while (!offer_termination());
3270 }
3271 
3272 class G1ParTask : public AbstractGangTask {
3273 protected:
3274   G1CollectedHeap*         _g1h;
3275   G1ParScanThreadStateSet* _pss;
3276   RefToScanQueueSet*       _queues;
3277   G1RootProcessor*         _root_processor;
3278   ParallelTaskTerminator   _terminator;
3279   uint                     _n_workers;
3280 
3281 public:
3282   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3283     : AbstractGangTask("G1 collection"),
3284       _g1h(g1h),
3285       _pss(per_thread_states),
3286       _queues(task_queues),
3287       _root_processor(root_processor),
3288       _terminator(n_workers, _queues),
3289       _n_workers(n_workers)
3290   {}
3291 
3292   void work(uint worker_id) {
3293     if (worker_id >= _n_workers) return;  // no work needed this round
3294 
3295     double start_sec = os::elapsedTime();
3296     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3297 
3298     {
3299       ResourceMark rm;
3300       HandleMark   hm;
3301 
3302       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
3303 
3304       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
3305       pss->set_ref_processor(rp);
3306 
3307       double start_strong_roots_sec = os::elapsedTime();
3308 
3309       _root_processor->evacuate_roots(pss->closures(), worker_id);
3310 
3311       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3312       // treating the nmethods visited to act as roots for concurrent marking.
3313       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3314       // objects copied by the current evacuation.
3315       _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3316                                                       pss->closures()->weak_codeblobs(),
3317                                                       worker_id);
3318 
3319       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3320 
3321       double term_sec = 0.0;
3322       size_t evac_term_attempts = 0;
3323       {
3324         double start = os::elapsedTime();
3325         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3326         evac.do_void();
3327 
3328         evac_term_attempts = evac.term_attempts();
3329         term_sec = evac.term_time();
3330         double elapsed_sec = os::elapsedTime() - start;
3331         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3332         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3333         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3334       }
3335 
3336       assert(pss->queue_is_empty(), "should be empty");
3337 
3338       if (log_is_enabled(Debug, gc, task, stats)) {
3339         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3340         size_t lab_waste;
3341         size_t lab_undo_waste;
3342         pss->waste(lab_waste, lab_undo_waste);
3343         _g1h->print_termination_stats(worker_id,
3344                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
3345                                       strong_roots_sec * 1000.0,                  /* strong roots time */
3346                                       term_sec * 1000.0,                          /* evac term time */
3347                                       evac_term_attempts,                         /* evac term attempts */
3348                                       lab_waste,                                  /* alloc buffer waste */
3349                                       lab_undo_waste                              /* undo waste */
3350                                       );
3351       }
3352 
3353       // Close the inner scope so that the ResourceMark and HandleMark
3354       // destructors are executed here and are included as part of the
3355       // "GC Worker Time".
3356     }
3357     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3358   }
3359 };
3360 
3361 void G1CollectedHeap::print_termination_stats_hdr() {
3362   log_debug(gc, task, stats)("GC Termination Stats");
3363   log_debug(gc, task, stats)("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
3364   log_debug(gc, task, stats)("thr     ms        ms      %%        ms      %%    attempts  total   alloc    undo");
3365   log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3366 }
3367 
3368 void G1CollectedHeap::print_termination_stats(uint worker_id,
3369                                               double elapsed_ms,
3370                                               double strong_roots_ms,
3371                                               double term_ms,
3372                                               size_t term_attempts,
3373                                               size_t alloc_buffer_waste,
3374                                               size_t undo_waste) const {
3375   log_debug(gc, task, stats)
3376               ("%3d %9.2f %9.2f %6.2f "
3377                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3378                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3379                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3380                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3381                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3382                alloc_buffer_waste * HeapWordSize / K,
3383                undo_waste * HeapWordSize / K);
3384 }
3385 
3386 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3387 private:
3388   BoolObjectClosure* _is_alive;
3389   G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3390 
3391   int _initial_string_table_size;
3392   int _initial_symbol_table_size;
3393 
3394   bool  _process_strings;
3395   int _strings_processed;
3396   int _strings_removed;
3397 
3398   bool  _process_symbols;
3399   int _symbols_processed;
3400   int _symbols_removed;
3401 
3402   bool _process_string_dedup;
3403 
3404 public:
3405   G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3406     AbstractGangTask("String/Symbol Unlinking"),
3407     _is_alive(is_alive),
3408     _dedup_closure(is_alive, NULL, false),
3409     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3410     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3411     _process_string_dedup(process_string_dedup) {
3412 
3413     _initial_string_table_size = StringTable::the_table()->table_size();
3414     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3415     if (process_strings) {
3416       StringTable::clear_parallel_claimed_index();
3417     }
3418     if (process_symbols) {
3419       SymbolTable::clear_parallel_claimed_index();
3420     }
3421   }
3422 
3423   ~G1StringAndSymbolCleaningTask() {
3424     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3425               "claim value %d after unlink less than initial string table size %d",
3426               StringTable::parallel_claimed_index(), _initial_string_table_size);
3427     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3428               "claim value %d after unlink less than initial symbol table size %d",
3429               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3430 
3431     log_info(gc, stringtable)(
3432         "Cleaned string and symbol table, "
3433         "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3434         "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3435         strings_processed(), strings_removed(),
3436         symbols_processed(), symbols_removed());
3437   }
3438 
3439   void work(uint worker_id) {
3440     int strings_processed = 0;
3441     int strings_removed = 0;
3442     int symbols_processed = 0;
3443     int symbols_removed = 0;
3444     if (_process_strings) {
3445       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3446       Atomic::add(strings_processed, &_strings_processed);
3447       Atomic::add(strings_removed, &_strings_removed);
3448     }
3449     if (_process_symbols) {
3450       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3451       Atomic::add(symbols_processed, &_symbols_processed);
3452       Atomic::add(symbols_removed, &_symbols_removed);
3453     }
3454     if (_process_string_dedup) {
3455       G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3456     }
3457   }
3458 
3459   size_t strings_processed() const { return (size_t)_strings_processed; }
3460   size_t strings_removed()   const { return (size_t)_strings_removed; }
3461 
3462   size_t symbols_processed() const { return (size_t)_symbols_processed; }
3463   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
3464 };
3465 
3466 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3467 private:
3468   static Monitor* _lock;
3469 
3470   BoolObjectClosure* const _is_alive;
3471   const bool               _unloading_occurred;
3472   const uint               _num_workers;
3473 
3474   // Variables used to claim nmethods.
3475   CompiledMethod* _first_nmethod;
3476   CompiledMethod* volatile _claimed_nmethod;
3477 
3478   // The list of nmethods that need to be processed by the second pass.
3479   CompiledMethod* volatile _postponed_list;
3480   volatile uint            _num_entered_barrier;
3481 
3482  public:
3483   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3484       _is_alive(is_alive),
3485       _unloading_occurred(unloading_occurred),
3486       _num_workers(num_workers),
3487       _first_nmethod(NULL),
3488       _claimed_nmethod(NULL),
3489       _postponed_list(NULL),
3490       _num_entered_barrier(0)
3491   {
3492     CompiledMethod::increase_unloading_clock();
3493     // Get first alive nmethod
3494     CompiledMethodIterator iter = CompiledMethodIterator();
3495     if(iter.next_alive()) {
3496       _first_nmethod = iter.method();
3497     }
3498     _claimed_nmethod = _first_nmethod;
3499   }
3500 
3501   ~G1CodeCacheUnloadingTask() {
3502     CodeCache::verify_clean_inline_caches();
3503 
3504     CodeCache::set_needs_cache_clean(false);
3505     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3506 
3507     CodeCache::verify_icholder_relocations();
3508   }
3509 
3510  private:
3511   void add_to_postponed_list(CompiledMethod* nm) {
3512       CompiledMethod* old;
3513       do {
3514         old = _postponed_list;
3515         nm->set_unloading_next(old);
3516       } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3517   }
3518 
3519   void clean_nmethod(CompiledMethod* nm) {
3520     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3521 
3522     if (postponed) {
3523       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3524       add_to_postponed_list(nm);
3525     }
3526 
3527     // Mark that this thread has been cleaned/unloaded.
3528     // After this call, it will be safe to ask if this nmethod was unloaded or not.
3529     nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3530   }
3531 
3532   void clean_nmethod_postponed(CompiledMethod* nm) {
3533     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3534   }
3535 
3536   static const int MaxClaimNmethods = 16;
3537 
3538   void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3539     CompiledMethod* first;
3540     CompiledMethodIterator last;
3541 
3542     do {
3543       *num_claimed_nmethods = 0;
3544 
3545       first = _claimed_nmethod;
3546       last = CompiledMethodIterator(first);
3547 
3548       if (first != NULL) {
3549 
3550         for (int i = 0; i < MaxClaimNmethods; i++) {
3551           if (!last.next_alive()) {
3552             break;
3553           }
3554           claimed_nmethods[i] = last.method();
3555           (*num_claimed_nmethods)++;
3556         }
3557       }
3558 
3559     } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3560   }
3561 
3562   CompiledMethod* claim_postponed_nmethod() {
3563     CompiledMethod* claim;
3564     CompiledMethod* next;
3565 
3566     do {
3567       claim = _postponed_list;
3568       if (claim == NULL) {
3569         return NULL;
3570       }
3571 
3572       next = claim->unloading_next();
3573 
3574     } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3575 
3576     return claim;
3577   }
3578 
3579  public:
3580   // Mark that we're done with the first pass of nmethod cleaning.
3581   void barrier_mark(uint worker_id) {
3582     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3583     _num_entered_barrier++;
3584     if (_num_entered_barrier == _num_workers) {
3585       ml.notify_all();
3586     }
3587   }
3588 
3589   // See if we have to wait for the other workers to
3590   // finish their first-pass nmethod cleaning work.
3591   void barrier_wait(uint worker_id) {
3592     if (_num_entered_barrier < _num_workers) {
3593       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3594       while (_num_entered_barrier < _num_workers) {
3595           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3596       }
3597     }
3598   }
3599 
3600   // Cleaning and unloading of nmethods. Some work has to be postponed
3601   // to the second pass, when we know which nmethods survive.
3602   void work_first_pass(uint worker_id) {
3603     // The first nmethods is claimed by the first worker.
3604     if (worker_id == 0 && _first_nmethod != NULL) {
3605       clean_nmethod(_first_nmethod);
3606       _first_nmethod = NULL;
3607     }
3608 
3609     int num_claimed_nmethods;
3610     CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3611 
3612     while (true) {
3613       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3614 
3615       if (num_claimed_nmethods == 0) {
3616         break;
3617       }
3618 
3619       for (int i = 0; i < num_claimed_nmethods; i++) {
3620         clean_nmethod(claimed_nmethods[i]);
3621       }
3622     }
3623   }
3624 
3625   void work_second_pass(uint worker_id) {
3626     CompiledMethod* nm;
3627     // Take care of postponed nmethods.
3628     while ((nm = claim_postponed_nmethod()) != NULL) {
3629       clean_nmethod_postponed(nm);
3630     }
3631   }
3632 };
3633 
3634 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3635 
3636 class G1KlassCleaningTask : public StackObj {
3637   BoolObjectClosure*                      _is_alive;
3638   volatile int                            _clean_klass_tree_claimed;
3639   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3640 
3641  public:
3642   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3643       _is_alive(is_alive),
3644       _clean_klass_tree_claimed(0),
3645       _klass_iterator() {
3646   }
3647 
3648  private:
3649   bool claim_clean_klass_tree_task() {
3650     if (_clean_klass_tree_claimed) {
3651       return false;
3652     }
3653 
3654     return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3655   }
3656 
3657   InstanceKlass* claim_next_klass() {
3658     Klass* klass;
3659     do {
3660       klass =_klass_iterator.next_klass();
3661     } while (klass != NULL && !klass->is_instance_klass());
3662 
3663     // this can be null so don't call InstanceKlass::cast
3664     return static_cast<InstanceKlass*>(klass);
3665   }
3666 
3667 public:
3668 
3669   void clean_klass(InstanceKlass* ik) {
3670     ik->clean_weak_instanceklass_links(_is_alive);
3671   }
3672 
3673   void work() {
3674     ResourceMark rm;
3675 
3676     // One worker will clean the subklass/sibling klass tree.
3677     if (claim_clean_klass_tree_task()) {
3678       Klass::clean_subklass_tree(_is_alive);
3679     }
3680 
3681     // All workers will help cleaning the classes,
3682     InstanceKlass* klass;
3683     while ((klass = claim_next_klass()) != NULL) {
3684       clean_klass(klass);
3685     }
3686   }
3687 };
3688 
3689 class G1ResolvedMethodCleaningTask : public StackObj {
3690   BoolObjectClosure* _is_alive;
3691   volatile int       _resolved_method_task_claimed;
3692 public:
3693   G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3694       _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3695 
3696   bool claim_resolved_method_task() {
3697     if (_resolved_method_task_claimed) {
3698       return false;
3699     }
3700     return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3701   }
3702 
3703   // These aren't big, one thread can do it all.
3704   void work() {
3705     if (claim_resolved_method_task()) {
3706       ResolvedMethodTable::unlink(_is_alive);
3707     }
3708   }
3709 };
3710 
3711 
3712 // To minimize the remark pause times, the tasks below are done in parallel.
3713 class G1ParallelCleaningTask : public AbstractGangTask {
3714 private:
3715   G1StringAndSymbolCleaningTask _string_symbol_task;
3716   G1CodeCacheUnloadingTask      _code_cache_task;
3717   G1KlassCleaningTask           _klass_cleaning_task;
3718   G1ResolvedMethodCleaningTask  _resolved_method_cleaning_task;
3719 
3720 public:
3721   // The constructor is run in the VMThread.
3722   G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3723       AbstractGangTask("Parallel Cleaning"),
3724       _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3725       _code_cache_task(num_workers, is_alive, unloading_occurred),
3726       _klass_cleaning_task(is_alive),
3727       _resolved_method_cleaning_task(is_alive) {
3728   }
3729 
3730   // The parallel work done by all worker threads.
3731   void work(uint worker_id) {
3732     // Do first pass of code cache cleaning.
3733     _code_cache_task.work_first_pass(worker_id);
3734 
3735     // Let the threads mark that the first pass is done.
3736     _code_cache_task.barrier_mark(worker_id);
3737 
3738     // Clean the Strings and Symbols.
3739     _string_symbol_task.work(worker_id);
3740 
3741     // Clean unreferenced things in the ResolvedMethodTable
3742     _resolved_method_cleaning_task.work();
3743 
3744     // Wait for all workers to finish the first code cache cleaning pass.
3745     _code_cache_task.barrier_wait(worker_id);
3746 
3747     // Do the second code cache cleaning work, which realize on
3748     // the liveness information gathered during the first pass.
3749     _code_cache_task.work_second_pass(worker_id);
3750 
3751     // Clean all klasses that were not unloaded.
3752     _klass_cleaning_task.work();
3753   }
3754 };
3755 
3756 
3757 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3758                                         bool class_unloading_occurred) {
3759   uint n_workers = workers()->active_workers();
3760 
3761   G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3762   workers()->run_task(&g1_unlink_task);
3763 }
3764 
3765 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3766                                        bool process_strings,
3767                                        bool process_symbols,
3768                                        bool process_string_dedup) {
3769   if (!process_strings && !process_symbols && !process_string_dedup) {
3770     // Nothing to clean.
3771     return;
3772   }
3773 
3774   G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3775   workers()->run_task(&g1_unlink_task);
3776 
3777 }
3778 
3779 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3780  private:
3781   DirtyCardQueueSet* _queue;
3782   G1CollectedHeap* _g1h;
3783  public:
3784   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3785     _queue(queue), _g1h(g1h) { }
3786 
3787   virtual void work(uint worker_id) {
3788     G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3789     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3790 
3791     RedirtyLoggedCardTableEntryClosure cl(_g1h);
3792     _queue->par_apply_closure_to_all_completed_buffers(&cl);
3793 
3794     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3795   }
3796 };
3797 
3798 void G1CollectedHeap::redirty_logged_cards() {
3799   double redirty_logged_cards_start = os::elapsedTime();
3800 
3801   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3802   dirty_card_queue_set().reset_for_par_iteration();
3803   workers()->run_task(&redirty_task);
3804 
3805   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3806   dcq.merge_bufferlists(&dirty_card_queue_set());
3807   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3808 
3809   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3810 }
3811 
3812 // Weak Reference Processing support
3813 
3814 // An always "is_alive" closure that is used to preserve referents.
3815 // If the object is non-null then it's alive.  Used in the preservation
3816 // of referent objects that are pointed to by reference objects
3817 // discovered by the CM ref processor.
3818 class G1AlwaysAliveClosure: public BoolObjectClosure {
3819   G1CollectedHeap* _g1;
3820 public:
3821   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3822   bool do_object_b(oop p) {
3823     if (p != NULL) {
3824       return true;
3825     }
3826     return false;
3827   }
3828 };
3829 
3830 bool G1STWIsAliveClosure::do_object_b(oop p) {
3831   // An object is reachable if it is outside the collection set,
3832   // or is inside and copied.
3833   return !_g1->is_in_cset(p) || p->is_forwarded();
3834 }
3835 
3836 // Non Copying Keep Alive closure
3837 class G1KeepAliveClosure: public OopClosure {
3838   G1CollectedHeap* _g1;
3839 public:
3840   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3841   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3842   void do_oop(oop* p) {
3843     oop obj = *p;
3844     assert(obj != NULL, "the caller should have filtered out NULL values");
3845 
3846     const InCSetState cset_state = _g1->in_cset_state(obj);
3847     if (!cset_state.is_in_cset_or_humongous()) {
3848       return;
3849     }
3850     if (cset_state.is_in_cset()) {
3851       assert( obj->is_forwarded(), "invariant" );
3852       *p = obj->forwardee();
3853     } else {
3854       assert(!obj->is_forwarded(), "invariant" );
3855       assert(cset_state.is_humongous(),
3856              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3857       _g1->set_humongous_is_live(obj);
3858     }
3859   }
3860 };
3861 
3862 // Copying Keep Alive closure - can be called from both
3863 // serial and parallel code as long as different worker
3864 // threads utilize different G1ParScanThreadState instances
3865 // and different queues.
3866 
3867 class G1CopyingKeepAliveClosure: public OopClosure {
3868   G1CollectedHeap*         _g1h;
3869   OopClosure*              _copy_non_heap_obj_cl;
3870   G1ParScanThreadState*    _par_scan_state;
3871 
3872 public:
3873   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3874                             OopClosure* non_heap_obj_cl,
3875                             G1ParScanThreadState* pss):
3876     _g1h(g1h),
3877     _copy_non_heap_obj_cl(non_heap_obj_cl),
3878     _par_scan_state(pss)
3879   {}
3880 
3881   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3882   virtual void do_oop(      oop* p) { do_oop_work(p); }
3883 
3884   template <class T> void do_oop_work(T* p) {
3885     oop obj = oopDesc::load_decode_heap_oop(p);
3886 
3887     if (_g1h->is_in_cset_or_humongous(obj)) {
3888       // If the referent object has been forwarded (either copied
3889       // to a new location or to itself in the event of an
3890       // evacuation failure) then we need to update the reference
3891       // field and, if both reference and referent are in the G1
3892       // heap, update the RSet for the referent.
3893       //
3894       // If the referent has not been forwarded then we have to keep
3895       // it alive by policy. Therefore we have copy the referent.
3896       //
3897       // If the reference field is in the G1 heap then we can push
3898       // on the PSS queue. When the queue is drained (after each
3899       // phase of reference processing) the object and it's followers
3900       // will be copied, the reference field set to point to the
3901       // new location, and the RSet updated. Otherwise we need to
3902       // use the the non-heap or metadata closures directly to copy
3903       // the referent object and update the pointer, while avoiding
3904       // updating the RSet.
3905 
3906       if (_g1h->is_in_g1_reserved(p)) {
3907         _par_scan_state->push_on_queue(p);
3908       } else {
3909         assert(!Metaspace::contains((const void*)p),
3910                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3911         _copy_non_heap_obj_cl->do_oop(p);
3912       }
3913     }
3914   }
3915 };
3916 
3917 // Serial drain queue closure. Called as the 'complete_gc'
3918 // closure for each discovered list in some of the
3919 // reference processing phases.
3920 
3921 class G1STWDrainQueueClosure: public VoidClosure {
3922 protected:
3923   G1CollectedHeap* _g1h;
3924   G1ParScanThreadState* _par_scan_state;
3925 
3926   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
3927 
3928 public:
3929   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3930     _g1h(g1h),
3931     _par_scan_state(pss)
3932   { }
3933 
3934   void do_void() {
3935     G1ParScanThreadState* const pss = par_scan_state();
3936     pss->trim_queue();
3937   }
3938 };
3939 
3940 // Parallel Reference Processing closures
3941 
3942 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3943 // processing during G1 evacuation pauses.
3944 
3945 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3946 private:
3947   G1CollectedHeap*          _g1h;
3948   G1ParScanThreadStateSet*  _pss;
3949   RefToScanQueueSet*        _queues;
3950   WorkGang*                 _workers;
3951   uint                      _active_workers;
3952 
3953 public:
3954   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3955                            G1ParScanThreadStateSet* per_thread_states,
3956                            WorkGang* workers,
3957                            RefToScanQueueSet *task_queues,
3958                            uint n_workers) :
3959     _g1h(g1h),
3960     _pss(per_thread_states),
3961     _queues(task_queues),
3962     _workers(workers),
3963     _active_workers(n_workers)
3964   {
3965     g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3966   }
3967 
3968   // Executes the given task using concurrent marking worker threads.
3969   virtual void execute(ProcessTask& task);
3970   virtual void execute(EnqueueTask& task);
3971 };
3972 
3973 // Gang task for possibly parallel reference processing
3974 
3975 class G1STWRefProcTaskProxy: public AbstractGangTask {
3976   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3977   ProcessTask&     _proc_task;
3978   G1CollectedHeap* _g1h;
3979   G1ParScanThreadStateSet* _pss;
3980   RefToScanQueueSet* _task_queues;
3981   ParallelTaskTerminator* _terminator;
3982 
3983 public:
3984   G1STWRefProcTaskProxy(ProcessTask& proc_task,
3985                         G1CollectedHeap* g1h,
3986                         G1ParScanThreadStateSet* per_thread_states,
3987                         RefToScanQueueSet *task_queues,
3988                         ParallelTaskTerminator* terminator) :
3989     AbstractGangTask("Process reference objects in parallel"),
3990     _proc_task(proc_task),
3991     _g1h(g1h),
3992     _pss(per_thread_states),
3993     _task_queues(task_queues),
3994     _terminator(terminator)
3995   {}
3996 
3997   virtual void work(uint worker_id) {
3998     // The reference processing task executed by a single worker.
3999     ResourceMark rm;
4000     HandleMark   hm;
4001 
4002     G1STWIsAliveClosure is_alive(_g1h);
4003 
4004     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4005     pss->set_ref_processor(NULL);
4006 
4007     // Keep alive closure.
4008     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4009 
4010     // Complete GC closure
4011     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4012 
4013     // Call the reference processing task's work routine.
4014     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4015 
4016     // Note we cannot assert that the refs array is empty here as not all
4017     // of the processing tasks (specifically phase2 - pp2_work) execute
4018     // the complete_gc closure (which ordinarily would drain the queue) so
4019     // the queue may not be empty.
4020   }
4021 };
4022 
4023 // Driver routine for parallel reference processing.
4024 // Creates an instance of the ref processing gang
4025 // task and has the worker threads execute it.
4026 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4027   assert(_workers != NULL, "Need parallel worker threads.");
4028 
4029   ParallelTaskTerminator terminator(_active_workers, _queues);
4030   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4031 
4032   _workers->run_task(&proc_task_proxy);
4033 }
4034 
4035 // Gang task for parallel reference enqueueing.
4036 
4037 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4038   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4039   EnqueueTask& _enq_task;
4040 
4041 public:
4042   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4043     AbstractGangTask("Enqueue reference objects in parallel"),
4044     _enq_task(enq_task)
4045   { }
4046 
4047   virtual void work(uint worker_id) {
4048     _enq_task.work(worker_id);
4049   }
4050 };
4051 
4052 // Driver routine for parallel reference enqueueing.
4053 // Creates an instance of the ref enqueueing gang
4054 // task and has the worker threads execute it.
4055 
4056 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4057   assert(_workers != NULL, "Need parallel worker threads.");
4058 
4059   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4060 
4061   _workers->run_task(&enq_task_proxy);
4062 }
4063 
4064 // End of weak reference support closures
4065 
4066 // Abstract task used to preserve (i.e. copy) any referent objects
4067 // that are in the collection set and are pointed to by reference
4068 // objects discovered by the CM ref processor.
4069 
4070 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4071 protected:
4072   G1CollectedHeap*         _g1h;
4073   G1ParScanThreadStateSet* _pss;
4074   RefToScanQueueSet*       _queues;
4075   ParallelTaskTerminator   _terminator;
4076   uint                     _n_workers;
4077 
4078 public:
4079   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4080     AbstractGangTask("ParPreserveCMReferents"),
4081     _g1h(g1h),
4082     _pss(per_thread_states),
4083     _queues(task_queues),
4084     _terminator(workers, _queues),
4085     _n_workers(workers)
4086   {
4087     g1h->ref_processor_cm()->set_active_mt_degree(workers);
4088   }
4089 
4090   void work(uint worker_id) {
4091     G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4092 
4093     ResourceMark rm;
4094     HandleMark   hm;
4095 
4096     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4097     pss->set_ref_processor(NULL);
4098     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4099 
4100     // Is alive closure
4101     G1AlwaysAliveClosure always_alive(_g1h);
4102 
4103     // Copying keep alive closure. Applied to referent objects that need
4104     // to be copied.
4105     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4106 
4107     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4108 
4109     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4110     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4111 
4112     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4113     // So this must be true - but assert just in case someone decides to
4114     // change the worker ids.
4115     assert(worker_id < limit, "sanity");
4116     assert(!rp->discovery_is_atomic(), "check this code");
4117 
4118     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4119     for (uint idx = worker_id; idx < limit; idx += stride) {
4120       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4121 
4122       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4123       while (iter.has_next()) {
4124         // Since discovery is not atomic for the CM ref processor, we
4125         // can see some null referent objects.
4126         iter.load_ptrs(DEBUG_ONLY(true));
4127         oop ref = iter.obj();
4128 
4129         // This will filter nulls.
4130         if (iter.is_referent_alive()) {
4131           iter.make_referent_alive();
4132         }
4133         iter.move_to_next();
4134       }
4135     }
4136 
4137     // Drain the queue - which may cause stealing
4138     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4139     drain_queue.do_void();
4140     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4141     assert(pss->queue_is_empty(), "should be");
4142   }
4143 };
4144 
4145 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4146   // Any reference objects, in the collection set, that were 'discovered'
4147   // by the CM ref processor should have already been copied (either by
4148   // applying the external root copy closure to the discovered lists, or
4149   // by following an RSet entry).
4150   //
4151   // But some of the referents, that are in the collection set, that these
4152   // reference objects point to may not have been copied: the STW ref
4153   // processor would have seen that the reference object had already
4154   // been 'discovered' and would have skipped discovering the reference,
4155   // but would not have treated the reference object as a regular oop.
4156   // As a result the copy closure would not have been applied to the
4157   // referent object.
4158   //
4159   // We need to explicitly copy these referent objects - the references
4160   // will be processed at the end of remarking.
4161   //
4162   // We also need to do this copying before we process the reference
4163   // objects discovered by the STW ref processor in case one of these
4164   // referents points to another object which is also referenced by an
4165   // object discovered by the STW ref processor.
4166   double preserve_cm_referents_time = 0.0;
4167 
4168   // To avoid spawning task when there is no work to do, check that
4169   // a concurrent cycle is active and that some references have been
4170   // discovered.
4171   if (concurrent_mark()->cm_thread()->during_cycle() &&
4172       ref_processor_cm()->has_discovered_references()) {
4173     double preserve_cm_referents_start = os::elapsedTime();
4174     uint no_of_gc_workers = workers()->active_workers();
4175     G1ParPreserveCMReferentsTask keep_cm_referents(this,
4176                                                    per_thread_states,
4177                                                    no_of_gc_workers,
4178                                                    _task_queues);
4179     workers()->run_task(&keep_cm_referents);
4180     preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4181   }
4182 
4183   g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4184 }
4185 
4186 // Weak Reference processing during an evacuation pause (part 1).
4187 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4188   double ref_proc_start = os::elapsedTime();
4189 
4190   ReferenceProcessor* rp = _ref_processor_stw;
4191   assert(rp->discovery_enabled(), "should have been enabled");
4192 
4193   // Closure to test whether a referent is alive.
4194   G1STWIsAliveClosure is_alive(this);
4195 
4196   // Even when parallel reference processing is enabled, the processing
4197   // of JNI refs is serial and performed serially by the current thread
4198   // rather than by a worker. The following PSS will be used for processing
4199   // JNI refs.
4200 
4201   // Use only a single queue for this PSS.
4202   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
4203   pss->set_ref_processor(NULL);
4204   assert(pss->queue_is_empty(), "pre-condition");
4205 
4206   // Keep alive closure.
4207   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4208 
4209   // Serial Complete GC closure
4210   G1STWDrainQueueClosure drain_queue(this, pss);
4211 
4212   // Setup the soft refs policy...
4213   rp->setup_policy(false);
4214 
4215   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4216 
4217   ReferenceProcessorStats stats;
4218   if (!rp->processing_is_mt()) {
4219     // Serial reference processing...
4220     stats = rp->process_discovered_references(&is_alive,
4221                                               &keep_alive,
4222                                               &drain_queue,
4223                                               NULL,
4224                                               pt);
4225   } else {
4226     uint no_of_gc_workers = workers()->active_workers();
4227 
4228     // Parallel reference processing
4229     assert(no_of_gc_workers <= rp->max_num_q(),
4230            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4231            no_of_gc_workers,  rp->max_num_q());
4232 
4233     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4234     stats = rp->process_discovered_references(&is_alive,
4235                                               &keep_alive,
4236                                               &drain_queue,
4237                                               &par_task_executor,
4238                                               pt);
4239   }
4240 
4241   _gc_tracer_stw->report_gc_reference_stats(stats);
4242 
4243   // We have completed copying any necessary live referent objects.
4244   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4245 
4246   double ref_proc_time = os::elapsedTime() - ref_proc_start;
4247   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4248 }
4249 
4250 // Weak Reference processing during an evacuation pause (part 2).
4251 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4252   double ref_enq_start = os::elapsedTime();
4253 
4254   ReferenceProcessor* rp = _ref_processor_stw;
4255   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4256 
4257   ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4258 
4259   // Now enqueue any remaining on the discovered lists on to
4260   // the pending list.
4261   if (!rp->processing_is_mt()) {
4262     // Serial reference processing...
4263     rp->enqueue_discovered_references(NULL, pt);
4264   } else {
4265     // Parallel reference enqueueing
4266 
4267     uint n_workers = workers()->active_workers();
4268 
4269     assert(n_workers <= rp->max_num_q(),
4270            "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4271            n_workers,  rp->max_num_q());
4272 
4273     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4274     rp->enqueue_discovered_references(&par_task_executor, pt);
4275   }
4276 
4277   rp->verify_no_references_recorded();
4278   assert(!rp->discovery_enabled(), "should have been disabled");
4279 
4280   // If during an initial mark pause we install a pending list head which is not otherwise reachable
4281   // ensure that it is marked in the bitmap for concurrent marking to discover.
4282   if (collector_state()->during_initial_mark_pause()) {
4283     oop pll_head = Universe::reference_pending_list();
4284     if (pll_head != NULL) {
4285       _cm->mark_in_next_bitmap(pll_head);
4286     }
4287   }
4288 
4289   // FIXME
4290   // CM's reference processing also cleans up the string and symbol tables.
4291   // Should we do that here also? We could, but it is a serial operation
4292   // and could significantly increase the pause time.
4293 
4294   double ref_enq_time = os::elapsedTime() - ref_enq_start;
4295   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4296 }
4297 
4298 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4299   double merge_pss_time_start = os::elapsedTime();
4300   per_thread_states->flush();
4301   g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4302 }
4303 
4304 void G1CollectedHeap::pre_evacuate_collection_set() {
4305   _expand_heap_after_alloc_failure = true;
4306   _evacuation_failed = false;
4307 
4308   // Disable the hot card cache.
4309   _hot_card_cache->reset_hot_cache_claimed_index();
4310   _hot_card_cache->set_use_cache(false);
4311 
4312   g1_rem_set()->prepare_for_oops_into_collection_set_do();
4313   _preserved_marks_set.assert_empty();
4314 
4315   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4316 
4317   // InitialMark needs claim bits to keep track of the marked-through CLDs.
4318   if (collector_state()->during_initial_mark_pause()) {
4319     double start_clear_claimed_marks = os::elapsedTime();
4320 
4321     ClassLoaderDataGraph::clear_claimed_marks();
4322 
4323     double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4324     phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4325   }
4326 }
4327 
4328 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4329   // Should G1EvacuationFailureALot be in effect for this GC?
4330   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4331 
4332   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4333 
4334   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4335 
4336   double start_par_time_sec = os::elapsedTime();
4337   double end_par_time_sec;
4338 
4339   {
4340     const uint n_workers = workers()->active_workers();
4341     G1RootProcessor root_processor(this, n_workers);
4342     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4343 
4344     print_termination_stats_hdr();
4345 
4346     workers()->run_task(&g1_par_task);
4347     end_par_time_sec = os::elapsedTime();
4348 
4349     // Closing the inner scope will execute the destructor
4350     // for the G1RootProcessor object. We record the current
4351     // elapsed time before closing the scope so that time
4352     // taken for the destructor is NOT included in the
4353     // reported parallel time.
4354   }
4355 
4356   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4357   phase_times->record_par_time(par_time_ms);
4358 
4359   double code_root_fixup_time_ms =
4360         (os::elapsedTime() - end_par_time_sec) * 1000.0;
4361   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4362 }
4363 
4364 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4365   // Process any discovered reference objects - we have
4366   // to do this _before_ we retire the GC alloc regions
4367   // as we may have to copy some 'reachable' referent
4368   // objects (and their reachable sub-graphs) that were
4369   // not copied during the pause.
4370   if (g1_policy()->should_process_references()) {
4371     preserve_cm_referents(per_thread_states);
4372     process_discovered_references(per_thread_states);
4373   } else {
4374     ref_processor_stw()->verify_no_references_recorded();
4375   }
4376 
4377   G1STWIsAliveClosure is_alive(this);
4378   G1KeepAliveClosure keep_alive(this);
4379 
4380   {
4381     double start = os::elapsedTime();
4382 
4383     WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4384 
4385     double time_ms = (os::elapsedTime() - start) * 1000.0;
4386     g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4387   }
4388 
4389   if (G1StringDedup::is_enabled()) {
4390     double fixup_start = os::elapsedTime();
4391 
4392     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4393 
4394     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4395     g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4396   }
4397 
4398   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4399 
4400   if (evacuation_failed()) {
4401     restore_after_evac_failure();
4402 
4403     // Reset the G1EvacuationFailureALot counters and flags
4404     // Note: the values are reset only when an actual
4405     // evacuation failure occurs.
4406     NOT_PRODUCT(reset_evacuation_should_fail();)
4407   }
4408 
4409   _preserved_marks_set.assert_empty();
4410 
4411   // Enqueue any remaining references remaining on the STW
4412   // reference processor's discovered lists. We need to do
4413   // this after the card table is cleaned (and verified) as
4414   // the act of enqueueing entries on to the pending list
4415   // will log these updates (and dirty their associated
4416   // cards). We need these updates logged to update any
4417   // RSets.
4418   if (g1_policy()->should_process_references()) {
4419     enqueue_discovered_references(per_thread_states);
4420   } else {
4421     g1_policy()->phase_times()->record_ref_enq_time(0);
4422   }
4423 
4424   _allocator->release_gc_alloc_regions(evacuation_info);
4425 
4426   merge_per_thread_state_info(per_thread_states);
4427 
4428   // Reset and re-enable the hot card cache.
4429   // Note the counts for the cards in the regions in the
4430   // collection set are reset when the collection set is freed.
4431   _hot_card_cache->reset_hot_cache();
4432   _hot_card_cache->set_use_cache(true);
4433 
4434   purge_code_root_memory();
4435 
4436   redirty_logged_cards();
4437 #if COMPILER2_OR_JVMCI
4438   double start = os::elapsedTime();
4439   DerivedPointerTable::update_pointers();
4440   g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4441 #endif
4442   g1_policy()->print_age_table();
4443 }
4444 
4445 void G1CollectedHeap::record_obj_copy_mem_stats() {
4446   g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4447 
4448   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4449                                                create_g1_evac_summary(&_old_evac_stats));
4450 }
4451 
4452 void G1CollectedHeap::free_region(HeapRegion* hr,
4453                                   FreeRegionList* free_list,
4454                                   bool skip_remset,
4455                                   bool skip_hot_card_cache,
4456                                   bool locked) {
4457   assert(!hr->is_free(), "the region should not be free");
4458   assert(!hr->is_empty(), "the region should not be empty");
4459   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4460   assert(free_list != NULL, "pre-condition");
4461 
4462   if (G1VerifyBitmaps) {
4463     MemRegion mr(hr->bottom(), hr->end());
4464     concurrent_mark()->clear_range_in_prev_bitmap(mr);
4465   }
4466 
4467   // Clear the card counts for this region.
4468   // Note: we only need to do this if the region is not young
4469   // (since we don't refine cards in young regions).
4470   if (!skip_hot_card_cache && !hr->is_young()) {
4471     _hot_card_cache->reset_card_counts(hr);
4472   }
4473   hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4474   free_list->add_ordered(hr);
4475 }
4476 
4477 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4478                                             FreeRegionList* free_list,
4479                                             bool skip_remset) {
4480   assert(hr->is_humongous(), "this is only for humongous regions");
4481   assert(free_list != NULL, "pre-condition");
4482   hr->clear_humongous();
4483   free_region(hr, free_list, skip_remset);
4484 }
4485 
4486 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4487                                            const uint humongous_regions_removed) {
4488   if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4489     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4490     _old_set.bulk_remove(old_regions_removed);
4491     _humongous_set.bulk_remove(humongous_regions_removed);
4492   }
4493 
4494 }
4495 
4496 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4497   assert(list != NULL, "list can't be null");
4498   if (!list->is_empty()) {
4499     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4500     _hrm.insert_list_into_free_list(list);
4501   }
4502 }
4503 
4504 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4505   decrease_used(bytes);
4506 }
4507 
4508 class G1ParScrubRemSetTask: public AbstractGangTask {
4509 protected:
4510   G1RemSet* _g1rs;
4511   HeapRegionClaimer _hrclaimer;
4512 
4513 public:
4514   G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4515     AbstractGangTask("G1 ScrubRS"),
4516     _g1rs(g1_rs),
4517     _hrclaimer(num_workers) {
4518   }
4519 
4520   void work(uint worker_id) {
4521     _g1rs->scrub(worker_id, &_hrclaimer);
4522   }
4523 };
4524 
4525 void G1CollectedHeap::scrub_rem_set() {
4526   uint num_workers = workers()->active_workers();
4527   G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4528   workers()->run_task(&g1_par_scrub_rs_task);
4529 }
4530 
4531 class G1FreeCollectionSetTask : public AbstractGangTask {
4532 private:
4533 
4534   // Closure applied to all regions in the collection set to do work that needs to
4535   // be done serially in a single thread.
4536   class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4537   private:
4538     EvacuationInfo* _evacuation_info;
4539     const size_t* _surviving_young_words;
4540 
4541     // Bytes used in successfully evacuated regions before the evacuation.
4542     size_t _before_used_bytes;
4543     // Bytes used in unsucessfully evacuated regions before the evacuation
4544     size_t _after_used_bytes;
4545 
4546     size_t _bytes_allocated_in_old_since_last_gc;
4547 
4548     size_t _failure_used_words;
4549     size_t _failure_waste_words;
4550 
4551     FreeRegionList _local_free_list;
4552   public:
4553     G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4554       HeapRegionClosure(),
4555       _evacuation_info(evacuation_info),
4556       _surviving_young_words(surviving_young_words),
4557       _before_used_bytes(0),
4558       _after_used_bytes(0),
4559       _bytes_allocated_in_old_since_last_gc(0),
4560       _failure_used_words(0),
4561       _failure_waste_words(0),
4562       _local_free_list("Local Region List for CSet Freeing") {
4563     }
4564 
4565     virtual bool doHeapRegion(HeapRegion* r) {
4566       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4567 
4568       assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4569       g1h->clear_in_cset(r);
4570 
4571       if (r->is_young()) {
4572         assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4573                "Young index %d is wrong for region %u of type %s with %u young regions",
4574                r->young_index_in_cset(),
4575                r->hrm_index(),
4576                r->get_type_str(),
4577                g1h->collection_set()->young_region_length());
4578         size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4579         r->record_surv_words_in_group(words_survived);
4580       }
4581 
4582       if (!r->evacuation_failed()) {
4583         assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4584         _before_used_bytes += r->used();
4585         g1h->free_region(r,
4586                          &_local_free_list,
4587                          true, /* skip_remset */
4588                          true, /* skip_hot_card_cache */
4589                          true  /* locked */);
4590       } else {
4591         r->uninstall_surv_rate_group();
4592         r->set_young_index_in_cset(-1);
4593         r->set_evacuation_failed(false);
4594         // When moving a young gen region to old gen, we "allocate" that whole region
4595         // there. This is in addition to any already evacuated objects. Notify the
4596         // policy about that.
4597         // Old gen regions do not cause an additional allocation: both the objects
4598         // still in the region and the ones already moved are accounted for elsewhere.
4599         if (r->is_young()) {
4600           _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4601         }
4602         // The region is now considered to be old.
4603         r->set_old();
4604         // Do some allocation statistics accounting. Regions that failed evacuation
4605         // are always made old, so there is no need to update anything in the young
4606         // gen statistics, but we need to update old gen statistics.
4607         size_t used_words = r->marked_bytes() / HeapWordSize;
4608 
4609         _failure_used_words += used_words;
4610         _failure_waste_words += HeapRegion::GrainWords - used_words;
4611 
4612         g1h->old_set_add(r);
4613         _after_used_bytes += r->used();
4614       }
4615       return false;
4616     }
4617 
4618     void complete_work() {
4619       G1CollectedHeap* g1h = G1CollectedHeap::heap();
4620 
4621       _evacuation_info->set_regions_freed(_local_free_list.length());
4622       _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4623 
4624       g1h->prepend_to_freelist(&_local_free_list);
4625       g1h->decrement_summary_bytes(_before_used_bytes);
4626 
4627       G1Policy* policy = g1h->g1_policy();
4628       policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4629 
4630       g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4631     }
4632   };
4633 
4634   G1CollectionSet* _collection_set;
4635   G1SerialFreeCollectionSetClosure _cl;
4636   const size_t* _surviving_young_words;
4637 
4638   size_t _rs_lengths;
4639 
4640   volatile jint _serial_work_claim;
4641 
4642   struct WorkItem {
4643     uint region_idx;
4644     bool is_young;
4645     bool evacuation_failed;
4646 
4647     WorkItem(HeapRegion* r) {
4648       region_idx = r->hrm_index();
4649       is_young = r->is_young();
4650       evacuation_failed = r->evacuation_failed();
4651     }
4652   };
4653 
4654   volatile size_t _parallel_work_claim;
4655   size_t _num_work_items;
4656   WorkItem* _work_items;
4657 
4658   void do_serial_work() {
4659     // Need to grab the lock to be allowed to modify the old region list.
4660     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4661     _collection_set->iterate(&_cl);
4662   }
4663 
4664   void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4665     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4666 
4667     HeapRegion* r = g1h->region_at(region_idx);
4668     assert(!g1h->is_on_master_free_list(r), "sanity");
4669 
4670     Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4671 
4672     if (!is_young) {
4673       g1h->_hot_card_cache->reset_card_counts(r);
4674     }
4675 
4676     if (!evacuation_failed) {
4677       r->rem_set()->clear_locked();
4678     }
4679   }
4680 
4681   class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4682   private:
4683     size_t _cur_idx;
4684     WorkItem* _work_items;
4685   public:
4686     G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4687 
4688     virtual bool doHeapRegion(HeapRegion* r) {
4689       _work_items[_cur_idx++] = WorkItem(r);
4690       return false;
4691     }
4692   };
4693 
4694   void prepare_work() {
4695     G1PrepareFreeCollectionSetClosure cl(_work_items);
4696     _collection_set->iterate(&cl);
4697   }
4698 
4699   void complete_work() {
4700     _cl.complete_work();
4701 
4702     G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4703     policy->record_max_rs_lengths(_rs_lengths);
4704     policy->cset_regions_freed();
4705   }
4706 public:
4707   G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4708     AbstractGangTask("G1 Free Collection Set"),
4709     _cl(evacuation_info, surviving_young_words),
4710     _collection_set(collection_set),
4711     _surviving_young_words(surviving_young_words),
4712     _serial_work_claim(0),
4713     _rs_lengths(0),
4714     _parallel_work_claim(0),
4715     _num_work_items(collection_set->region_length()),
4716     _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4717     prepare_work();
4718   }
4719 
4720   ~G1FreeCollectionSetTask() {
4721     complete_work();
4722     FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4723   }
4724 
4725   // Chunk size for work distribution. The chosen value has been determined experimentally
4726   // to be a good tradeoff between overhead and achievable parallelism.
4727   static uint chunk_size() { return 32; }
4728 
4729   virtual void work(uint worker_id) {
4730     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4731 
4732     // Claim serial work.
4733     if (_serial_work_claim == 0) {
4734       jint value = Atomic::add(1, &_serial_work_claim) - 1;
4735       if (value == 0) {
4736         double serial_time = os::elapsedTime();
4737         do_serial_work();
4738         timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4739       }
4740     }
4741 
4742     // Start parallel work.
4743     double young_time = 0.0;
4744     bool has_young_time = false;
4745     double non_young_time = 0.0;
4746     bool has_non_young_time = false;
4747 
4748     while (true) {
4749       size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4750       size_t cur = end - chunk_size();
4751 
4752       if (cur >= _num_work_items) {
4753         break;
4754       }
4755 
4756       double start_time = os::elapsedTime();
4757 
4758       end = MIN2(end, _num_work_items);
4759 
4760       for (; cur < end; cur++) {
4761         bool is_young = _work_items[cur].is_young;
4762 
4763         do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4764 
4765         double end_time = os::elapsedTime();
4766         double time_taken = end_time - start_time;
4767         if (is_young) {
4768           young_time += time_taken;
4769           has_young_time = true;
4770         } else {
4771           non_young_time += time_taken;
4772           has_non_young_time = true;
4773         }
4774         start_time = end_time;
4775       }
4776     }
4777 
4778     if (has_young_time) {
4779       timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4780     }
4781     if (has_non_young_time) {
4782       timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4783     }
4784   }
4785 };
4786 
4787 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4788   _eden.clear();
4789 
4790   double free_cset_start_time = os::elapsedTime();
4791 
4792   {
4793     uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4794     uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4795 
4796     G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4797 
4798     log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4799                         cl.name(),
4800                         num_workers,
4801                         _collection_set.region_length());
4802     workers()->run_task(&cl, num_workers);
4803   }
4804   g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4805 
4806   collection_set->clear();
4807 }
4808 
4809 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4810  private:
4811   FreeRegionList* _free_region_list;
4812   HeapRegionSet* _proxy_set;
4813   uint _humongous_objects_reclaimed;
4814   uint _humongous_regions_reclaimed;
4815   size_t _freed_bytes;
4816  public:
4817 
4818   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4819     _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4820   }
4821 
4822   virtual bool doHeapRegion(HeapRegion* r) {
4823     if (!r->is_starts_humongous()) {
4824       return false;
4825     }
4826 
4827     G1CollectedHeap* g1h = G1CollectedHeap::heap();
4828 
4829     oop obj = (oop)r->bottom();
4830     G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4831 
4832     // The following checks whether the humongous object is live are sufficient.
4833     // The main additional check (in addition to having a reference from the roots
4834     // or the young gen) is whether the humongous object has a remembered set entry.
4835     //
4836     // A humongous object cannot be live if there is no remembered set for it
4837     // because:
4838     // - there can be no references from within humongous starts regions referencing
4839     // the object because we never allocate other objects into them.
4840     // (I.e. there are no intra-region references that may be missed by the
4841     // remembered set)
4842     // - as soon there is a remembered set entry to the humongous starts region
4843     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4844     // until the end of a concurrent mark.
4845     //
4846     // It is not required to check whether the object has been found dead by marking
4847     // or not, in fact it would prevent reclamation within a concurrent cycle, as
4848     // all objects allocated during that time are considered live.
4849     // SATB marking is even more conservative than the remembered set.
4850     // So if at this point in the collection there is no remembered set entry,
4851     // nobody has a reference to it.
4852     // At the start of collection we flush all refinement logs, and remembered sets
4853     // are completely up-to-date wrt to references to the humongous object.
4854     //
4855     // Other implementation considerations:
4856     // - never consider object arrays at this time because they would pose
4857     // considerable effort for cleaning up the the remembered sets. This is
4858     // required because stale remembered sets might reference locations that
4859     // are currently allocated into.
4860     uint region_idx = r->hrm_index();
4861     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4862         !r->rem_set()->is_empty()) {
4863       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",
4864                                region_idx,
4865                                (size_t)obj->size() * HeapWordSize,
4866                                p2i(r->bottom()),
4867                                r->rem_set()->occupied(),
4868                                r->rem_set()->strong_code_roots_list_length(),
4869                                next_bitmap->is_marked(r->bottom()),
4870                                g1h->is_humongous_reclaim_candidate(region_idx),
4871                                obj->is_typeArray()
4872                               );
4873       return false;
4874     }
4875 
4876     guarantee(obj->is_typeArray(),
4877               "Only eagerly reclaiming type arrays is supported, but the object "
4878               PTR_FORMAT " is not.", p2i(r->bottom()));
4879 
4880     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",
4881                              region_idx,
4882                              (size_t)obj->size() * HeapWordSize,
4883                              p2i(r->bottom()),
4884                              r->rem_set()->occupied(),
4885                              r->rem_set()->strong_code_roots_list_length(),
4886                              next_bitmap->is_marked(r->bottom()),
4887                              g1h->is_humongous_reclaim_candidate(region_idx),
4888                              obj->is_typeArray()
4889                             );
4890 
4891     // Need to clear mark bit of the humongous object if already set.
4892     if (next_bitmap->is_marked(r->bottom())) {
4893       next_bitmap->clear(r->bottom());
4894     }
4895     _humongous_objects_reclaimed++;
4896     do {
4897       HeapRegion* next = g1h->next_region_in_humongous(r);
4898       _freed_bytes += r->used();
4899       r->set_containing_set(NULL);
4900       _humongous_regions_reclaimed++;
4901       g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4902       r = next;
4903     } while (r != NULL);
4904 
4905     return false;
4906   }
4907 
4908   uint humongous_objects_reclaimed() {
4909     return _humongous_objects_reclaimed;
4910   }
4911 
4912   uint humongous_regions_reclaimed() {
4913     return _humongous_regions_reclaimed;
4914   }
4915 
4916   size_t bytes_freed() const {
4917     return _freed_bytes;
4918   }
4919 };
4920 
4921 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4922   assert_at_safepoint(true);
4923 
4924   if (!G1EagerReclaimHumongousObjects ||
4925       (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4926     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4927     return;
4928   }
4929 
4930   double start_time = os::elapsedTime();
4931 
4932   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4933 
4934   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4935   heap_region_iterate(&cl);
4936 
4937   remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4938 
4939   G1HRPrinter* hrp = hr_printer();
4940   if (hrp->is_active()) {
4941     FreeRegionListIterator iter(&local_cleanup_list);
4942     while (iter.more_available()) {
4943       HeapRegion* hr = iter.get_next();
4944       hrp->cleanup(hr);
4945     }
4946   }
4947 
4948   prepend_to_freelist(&local_cleanup_list);
4949   decrement_summary_bytes(cl.bytes_freed());
4950 
4951   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4952                                                                     cl.humongous_objects_reclaimed());
4953 }
4954 
4955 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4956 public:
4957   virtual bool doHeapRegion(HeapRegion* r) {
4958     assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4959     G1CollectedHeap::heap()->clear_in_cset(r);
4960     r->set_young_index_in_cset(-1);
4961     return false;
4962   }
4963 };
4964 
4965 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4966   G1AbandonCollectionSetClosure cl;
4967   collection_set->iterate(&cl);
4968 
4969   collection_set->clear();
4970   collection_set->stop_incremental_building();
4971 }
4972 
4973 void G1CollectedHeap::set_free_regions_coming() {
4974   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4975 
4976   assert(!free_regions_coming(), "pre-condition");
4977   _free_regions_coming = true;
4978 }
4979 
4980 void G1CollectedHeap::reset_free_regions_coming() {
4981   assert(free_regions_coming(), "pre-condition");
4982 
4983   {
4984     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4985     _free_regions_coming = false;
4986     SecondaryFreeList_lock->notify_all();
4987   }
4988 
4989   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4990 }
4991 
4992 void G1CollectedHeap::wait_while_free_regions_coming() {
4993   // Most of the time we won't have to wait, so let's do a quick test
4994   // first before we take the lock.
4995   if (!free_regions_coming()) {
4996     return;
4997   }
4998 
4999   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5000 
5001   {
5002     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5003     while (free_regions_coming()) {
5004       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5005     }
5006   }
5007 
5008   log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5009 }
5010 
5011 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5012   return _allocator->is_retained_old_region(hr);
5013 }
5014 
5015 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5016   _eden.add(hr);
5017   _g1_policy->set_region_eden(hr);
5018 }
5019 
5020 #ifdef ASSERT
5021 
5022 class NoYoungRegionsClosure: public HeapRegionClosure {
5023 private:
5024   bool _success;
5025 public:
5026   NoYoungRegionsClosure() : _success(true) { }
5027   bool doHeapRegion(HeapRegion* r) {
5028     if (r->is_young()) {
5029       log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5030                             p2i(r->bottom()), p2i(r->end()));
5031       _success = false;
5032     }
5033     return false;
5034   }
5035   bool success() { return _success; }
5036 };
5037 
5038 bool G1CollectedHeap::check_young_list_empty() {
5039   bool ret = (young_regions_count() == 0);
5040 
5041   NoYoungRegionsClosure closure;
5042   heap_region_iterate(&closure);
5043   ret = ret && closure.success();
5044 
5045   return ret;
5046 }
5047 
5048 #endif // ASSERT
5049 
5050 class TearDownRegionSetsClosure : public HeapRegionClosure {
5051 private:
5052   HeapRegionSet *_old_set;
5053 
5054 public:
5055   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5056 
5057   bool doHeapRegion(HeapRegion* r) {
5058     if (r->is_old()) {
5059       _old_set->remove(r);
5060     } else if(r->is_young()) {
5061       r->uninstall_surv_rate_group();
5062     } else {
5063       // We ignore free regions, we'll empty the free list afterwards.
5064       // We ignore humongous regions, we're not tearing down the
5065       // humongous regions set.
5066       assert(r->is_free() || r->is_humongous(),
5067              "it cannot be another type");
5068     }
5069     return false;
5070   }
5071 
5072   ~TearDownRegionSetsClosure() {
5073     assert(_old_set->is_empty(), "post-condition");
5074   }
5075 };
5076 
5077 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5078   assert_at_safepoint(true /* should_be_vm_thread */);
5079 
5080   if (!free_list_only) {
5081     TearDownRegionSetsClosure cl(&_old_set);
5082     heap_region_iterate(&cl);
5083 
5084     // Note that emptying the _young_list is postponed and instead done as
5085     // the first step when rebuilding the regions sets again. The reason for
5086     // this is that during a full GC string deduplication needs to know if
5087     // a collected region was young or old when the full GC was initiated.
5088   }
5089   _hrm.remove_all_free_regions();
5090 }
5091 
5092 void G1CollectedHeap::increase_used(size_t bytes) {
5093   _summary_bytes_used += bytes;
5094 }
5095 
5096 void G1CollectedHeap::decrease_used(size_t bytes) {
5097   assert(_summary_bytes_used >= bytes,
5098          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5099          _summary_bytes_used, bytes);
5100   _summary_bytes_used -= bytes;
5101 }
5102 
5103 void G1CollectedHeap::set_used(size_t bytes) {
5104   _summary_bytes_used = bytes;
5105 }
5106 
5107 class RebuildRegionSetsClosure : public HeapRegionClosure {
5108 private:
5109   bool            _free_list_only;
5110   HeapRegionSet*   _old_set;
5111   HeapRegionManager*   _hrm;
5112   size_t          _total_used;
5113 
5114 public:
5115   RebuildRegionSetsClosure(bool free_list_only,
5116                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5117     _free_list_only(free_list_only),
5118     _old_set(old_set), _hrm(hrm), _total_used(0) {
5119     assert(_hrm->num_free_regions() == 0, "pre-condition");
5120     if (!free_list_only) {
5121       assert(_old_set->is_empty(), "pre-condition");
5122     }
5123   }
5124 
5125   bool doHeapRegion(HeapRegion* r) {
5126     if (r->is_empty()) {
5127       // Add free regions to the free list
5128       r->set_free();
5129       r->set_allocation_context(AllocationContext::system());
5130       _hrm->insert_into_free_list(r);
5131     } else if (!_free_list_only) {
5132 
5133       if (r->is_humongous()) {
5134         // We ignore humongous regions. We left the humongous set unchanged.
5135       } else {
5136         assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5137         // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5138         r->move_to_old();
5139         _old_set->add(r);
5140       }
5141       _total_used += r->used();
5142     }
5143 
5144     return false;
5145   }
5146 
5147   size_t total_used() {
5148     return _total_used;
5149   }
5150 };
5151 
5152 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5153   assert_at_safepoint(true /* should_be_vm_thread */);
5154 
5155   if (!free_list_only) {
5156     _eden.clear();
5157     _survivor.clear();
5158   }
5159 
5160   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5161   heap_region_iterate(&cl);
5162 
5163   if (!free_list_only) {
5164     set_used(cl.total_used());
5165     if (_archive_allocator != NULL) {
5166       _archive_allocator->clear_used();
5167     }
5168   }
5169   assert(used_unlocked() == recalculate_used(),
5170          "inconsistent used_unlocked(), "
5171          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5172          used_unlocked(), recalculate_used());
5173 }
5174 
5175 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5176   HeapRegion* hr = heap_region_containing(p);
5177   return hr->is_in(p);
5178 }
5179 
5180 // Methods for the mutator alloc region
5181 
5182 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5183                                                       bool force) {
5184   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5185   bool should_allocate = g1_policy()->should_allocate_mutator_region();
5186   if (force || should_allocate) {
5187     HeapRegion* new_alloc_region = new_region(word_size,
5188                                               false /* is_old */,
5189                                               false /* do_expand */);
5190     if (new_alloc_region != NULL) {
5191       set_region_short_lived_locked(new_alloc_region);
5192       _hr_printer.alloc(new_alloc_region, !should_allocate);
5193       _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5194       return new_alloc_region;
5195     }
5196   }
5197   return NULL;
5198 }
5199 
5200 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5201                                                   size_t allocated_bytes) {
5202   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5203   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5204 
5205   collection_set()->add_eden_region(alloc_region);
5206   increase_used(allocated_bytes);
5207   _hr_printer.retire(alloc_region);
5208   // We update the eden sizes here, when the region is retired,
5209   // instead of when it's allocated, since this is the point that its
5210   // used space has been recored in _summary_bytes_used.
5211   g1mm()->update_eden_size();
5212 }
5213 
5214 // Methods for the GC alloc regions
5215 
5216 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5217   if (dest.is_old()) {
5218     return true;
5219   } else {
5220     return survivor_regions_count() < g1_policy()->max_survivor_regions();
5221   }
5222 }
5223 
5224 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5225   assert(FreeList_lock->owned_by_self(), "pre-condition");
5226 
5227   if (!has_more_regions(dest)) {
5228     return NULL;
5229   }
5230 
5231   const bool is_survivor = dest.is_young();
5232 
5233   HeapRegion* new_alloc_region = new_region(word_size,
5234                                             !is_survivor,
5235                                             true /* do_expand */);
5236   if (new_alloc_region != NULL) {
5237     // We really only need to do this for old regions given that we
5238     // should never scan survivors. But it doesn't hurt to do it
5239     // for survivors too.
5240     new_alloc_region->record_timestamp();
5241     if (is_survivor) {
5242       new_alloc_region->set_survivor();
5243       _survivor.add(new_alloc_region);
5244       _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5245     } else {
5246       new_alloc_region->set_old();
5247       _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5248     }
5249     _hr_printer.alloc(new_alloc_region);
5250     bool during_im = collector_state()->during_initial_mark_pause();
5251     new_alloc_region->note_start_of_copying(during_im);
5252     return new_alloc_region;
5253   }
5254   return NULL;
5255 }
5256 
5257 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5258                                              size_t allocated_bytes,
5259                                              InCSetState dest) {
5260   bool during_im = collector_state()->during_initial_mark_pause();
5261   alloc_region->note_end_of_copying(during_im);
5262   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5263   if (dest.is_old()) {
5264     _old_set.add(alloc_region);
5265   }
5266   _hr_printer.retire(alloc_region);
5267 }
5268 
5269 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5270   bool expanded = false;
5271   uint index = _hrm.find_highest_free(&expanded);
5272 
5273   if (index != G1_NO_HRM_INDEX) {
5274     if (expanded) {
5275       log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5276                                 HeapRegion::GrainWords * HeapWordSize);
5277     }
5278     _hrm.allocate_free_regions_starting_at(index, 1);
5279     return region_at(index);
5280   }
5281   return NULL;
5282 }
5283 
5284 // Optimized nmethod scanning
5285 
5286 class RegisterNMethodOopClosure: public OopClosure {
5287   G1CollectedHeap* _g1h;
5288   nmethod* _nm;
5289 
5290   template <class T> void do_oop_work(T* p) {
5291     T heap_oop = oopDesc::load_heap_oop(p);
5292     if (!oopDesc::is_null(heap_oop)) {
5293       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5294       HeapRegion* hr = _g1h->heap_region_containing(obj);
5295       assert(!hr->is_continues_humongous(),
5296              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5297              " starting at " HR_FORMAT,
5298              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5299 
5300       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5301       hr->add_strong_code_root_locked(_nm);
5302     }
5303   }
5304 
5305 public:
5306   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5307     _g1h(g1h), _nm(nm) {}
5308 
5309   void do_oop(oop* p)       { do_oop_work(p); }
5310   void do_oop(narrowOop* p) { do_oop_work(p); }
5311 };
5312 
5313 class UnregisterNMethodOopClosure: public OopClosure {
5314   G1CollectedHeap* _g1h;
5315   nmethod* _nm;
5316 
5317   template <class T> void do_oop_work(T* p) {
5318     T heap_oop = oopDesc::load_heap_oop(p);
5319     if (!oopDesc::is_null(heap_oop)) {
5320       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5321       HeapRegion* hr = _g1h->heap_region_containing(obj);
5322       assert(!hr->is_continues_humongous(),
5323              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5324              " starting at " HR_FORMAT,
5325              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5326 
5327       hr->remove_strong_code_root(_nm);
5328     }
5329   }
5330 
5331 public:
5332   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5333     _g1h(g1h), _nm(nm) {}
5334 
5335   void do_oop(oop* p)       { do_oop_work(p); }
5336   void do_oop(narrowOop* p) { do_oop_work(p); }
5337 };
5338 
5339 // Returns true if the reference points to an object that
5340 // can move in an incremental collection.
5341 bool G1CollectedHeap::is_scavengable(oop obj) {
5342   HeapRegion* hr = heap_region_containing(obj);
5343   return !hr->is_pinned();
5344 }
5345 
5346 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5347   guarantee(nm != NULL, "sanity");
5348   RegisterNMethodOopClosure reg_cl(this, nm);
5349   nm->oops_do(&reg_cl);
5350 }
5351 
5352 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5353   guarantee(nm != NULL, "sanity");
5354   UnregisterNMethodOopClosure reg_cl(this, nm);
5355   nm->oops_do(&reg_cl, true);
5356 }
5357 
5358 void G1CollectedHeap::purge_code_root_memory() {
5359   double purge_start = os::elapsedTime();
5360   G1CodeRootSet::purge();
5361   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5362   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5363 }
5364 
5365 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5366   G1CollectedHeap* _g1h;
5367 
5368 public:
5369   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5370     _g1h(g1h) {}
5371 
5372   void do_code_blob(CodeBlob* cb) {
5373     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5374     if (nm == NULL) {
5375       return;
5376     }
5377 
5378     if (ScavengeRootsInCode) {
5379       _g1h->register_nmethod(nm);
5380     }
5381   }
5382 };
5383 
5384 void G1CollectedHeap::rebuild_strong_code_roots() {
5385   RebuildStrongCodeRootClosure blob_cl(this);
5386   CodeCache::blobs_do(&blob_cl);
5387 }
5388 
5389 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5390   GrowableArray<GCMemoryManager*> memory_managers(2);
5391   memory_managers.append(&_memory_manager);
5392   memory_managers.append(&_full_gc_memory_manager);
5393   return memory_managers;
5394 }
5395 
5396 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5397   GrowableArray<MemoryPool*> memory_pools(3);
5398   memory_pools.append(_eden_pool);
5399   memory_pools.append(_survivor_pool);
5400   memory_pools.append(_old_pool);
5401   return memory_pools;
5402 }
--- EOF ---