1 /*
   2  * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/metadataOnStackMark.hpp"
  27 #include "classfile/stringTable.hpp"
  28 #include "code/codeCache.hpp"
  29 #include "code/icBuffer.hpp"
  30 #include "gc/g1/bufferingOopClosure.hpp"
  31 #include "gc/g1/concurrentG1Refine.hpp"
  32 #include "gc/g1/concurrentG1RefineThread.hpp"
  33 #include "gc/g1/concurrentMarkThread.inline.hpp"
  34 #include "gc/g1/g1Allocator.inline.hpp"
  35 #include "gc/g1/g1CollectedHeap.inline.hpp"
  36 #include "gc/g1/g1CollectorPolicy.hpp"
  37 #include "gc/g1/g1CollectorState.hpp"
  38 #include "gc/g1/g1ErgoVerbose.hpp"
  39 #include "gc/g1/g1EvacFailure.hpp"
  40 #include "gc/g1/g1EvacStats.inline.hpp"
  41 #include "gc/g1/g1GCPhaseTimes.hpp"
  42 #include "gc/g1/g1Log.hpp"
  43 #include "gc/g1/g1MarkSweep.hpp"
  44 #include "gc/g1/g1OopClosures.inline.hpp"
  45 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  46 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  47 #include "gc/g1/g1RemSet.inline.hpp"
  48 #include "gc/g1/g1RootClosures.hpp"
  49 #include "gc/g1/g1RootProcessor.hpp"
  50 #include "gc/g1/g1StringDedup.hpp"
  51 #include "gc/g1/g1YCTypes.hpp"
  52 #include "gc/g1/heapRegion.inline.hpp"
  53 #include "gc/g1/heapRegionRemSet.hpp"
  54 #include "gc/g1/heapRegionSet.inline.hpp"
  55 #include "gc/g1/suspendibleThreadSet.hpp"
  56 #include "gc/g1/vm_operations_g1.hpp"
  57 #include "gc/shared/gcHeapSummary.hpp"
  58 #include "gc/shared/gcId.hpp"
  59 #include "gc/shared/gcLocker.inline.hpp"
  60 #include "gc/shared/gcTimer.hpp"
  61 #include "gc/shared/gcTrace.hpp"
  62 #include "gc/shared/gcTraceTime.hpp"
  63 #include "gc/shared/generationSpec.hpp"
  64 #include "gc/shared/isGCActiveMark.hpp"
  65 #include "gc/shared/referenceProcessor.hpp"
  66 #include "gc/shared/taskqueue.inline.hpp"
  67 #include "memory/allocation.hpp"
  68 #include "memory/iterator.hpp"
  69 #include "oops/oop.inline.hpp"
  70 #include "runtime/atomic.inline.hpp"
  71 #include "runtime/init.hpp"
  72 #include "runtime/orderAccess.inline.hpp"
  73 #include "runtime/vmThread.hpp"
  74 #include "utilities/globalDefinitions.hpp"
  75 #include "utilities/stack.inline.hpp"
  76 
  77 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  78 
  79 // INVARIANTS/NOTES
  80 //
  81 // All allocation activity covered by the G1CollectedHeap interface is
  82 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  83 // and allocate_new_tlab, which are the "entry" points to the
  84 // allocation code from the rest of the JVM.  (Note that this does not
  85 // apply to TLAB allocation, which is not part of this interface: it
  86 // is done by clients of this interface.)
  87 
  88 // Local to this file.
  89 
  90 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  91   bool _concurrent;
  92 public:
  93   RefineCardTableEntryClosure() : _concurrent(true) { }
  94 
  95   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
  96     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
  97     // This path is executed by the concurrent refine or mutator threads,
  98     // concurrently, and so we do not care if card_ptr contains references
  99     // that point into the collection set.
 100     assert(!oops_into_cset, "should be");
 101 
 102     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 103       // Caller will actually yield.
 104       return false;
 105     }
 106     // Otherwise, we finished successfully; return true.
 107     return true;
 108   }
 109 
 110   void set_concurrent(bool b) { _concurrent = b; }
 111 };
 112 
 113 
 114 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 115  private:
 116   size_t _num_processed;
 117 
 118  public:
 119   RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
 120 
 121   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 122     *card_ptr = CardTableModRefBS::dirty_card_val();
 123     _num_processed++;
 124     return true;
 125   }
 126 
 127   size_t num_processed() const { return _num_processed; }
 128 };
 129 
 130 
 131 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 132   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 133 }
 134 
 135 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 136   // The from card cache is not the memory that is actually committed. So we cannot
 137   // take advantage of the zero_filled parameter.
 138   reset_from_card_cache(start_idx, num_regions);
 139 }
 140 
 141 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 142 {
 143   // Claim the right to put the region on the dirty cards region list
 144   // by installing a self pointer.
 145   HeapRegion* next = hr->get_next_dirty_cards_region();
 146   if (next == NULL) {
 147     HeapRegion* res = (HeapRegion*)
 148       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 149                           NULL);
 150     if (res == NULL) {
 151       HeapRegion* head;
 152       do {
 153         // Put the region to the dirty cards region list.
 154         head = _dirty_cards_region_list;
 155         next = (HeapRegion*)
 156           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 157         if (next == head) {
 158           assert(hr->get_next_dirty_cards_region() == hr,
 159                  "hr->get_next_dirty_cards_region() != hr");
 160           if (next == NULL) {
 161             // The last region in the list points to itself.
 162             hr->set_next_dirty_cards_region(hr);
 163           } else {
 164             hr->set_next_dirty_cards_region(next);
 165           }
 166         }
 167       } while (next != head);
 168     }
 169   }
 170 }
 171 
 172 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 173 {
 174   HeapRegion* head;
 175   HeapRegion* hr;
 176   do {
 177     head = _dirty_cards_region_list;
 178     if (head == NULL) {
 179       return NULL;
 180     }
 181     HeapRegion* new_head = head->get_next_dirty_cards_region();
 182     if (head == new_head) {
 183       // The last region.
 184       new_head = NULL;
 185     }
 186     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 187                                           head);
 188   } while (hr != head);
 189   assert(hr != NULL, "invariant");
 190   hr->set_next_dirty_cards_region(NULL);
 191   return hr;
 192 }
 193 
 194 // Returns true if the reference points to an object that
 195 // can move in an incremental collection.
 196 bool G1CollectedHeap::is_scavengable(const void* p) {
 197   HeapRegion* hr = heap_region_containing(p);
 198   return !hr->is_pinned();
 199 }
 200 
 201 // Private methods.
 202 
 203 HeapRegion*
 204 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 205   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 206   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 207     if (!_secondary_free_list.is_empty()) {
 208       if (G1ConcRegionFreeingVerbose) {
 209         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 210                                "secondary_free_list has %u entries",
 211                                _secondary_free_list.length());
 212       }
 213       // It looks as if there are free regions available on the
 214       // secondary_free_list. Let's move them to the free_list and try
 215       // again to allocate from it.
 216       append_secondary_free_list();
 217 
 218       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 219              "empty we should have moved at least one entry to the free_list");
 220       HeapRegion* res = _hrm.allocate_free_region(is_old);
 221       if (G1ConcRegionFreeingVerbose) {
 222         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 223                                "allocated " HR_FORMAT " from secondary_free_list",
 224                                HR_FORMAT_PARAMS(res));
 225       }
 226       return res;
 227     }
 228 
 229     // Wait here until we get notified either when (a) there are no
 230     // more free regions coming or (b) some regions have been moved on
 231     // the secondary_free_list.
 232     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 233   }
 234 
 235   if (G1ConcRegionFreeingVerbose) {
 236     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 237                            "could not allocate from secondary_free_list");
 238   }
 239   return NULL;
 240 }
 241 
 242 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 243   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 244          "the only time we use this to allocate a humongous region is "
 245          "when we are allocating a single humongous region");
 246 
 247   HeapRegion* res;
 248   if (G1StressConcRegionFreeing) {
 249     if (!_secondary_free_list.is_empty()) {
 250       if (G1ConcRegionFreeingVerbose) {
 251         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 252                                "forced to look at the secondary_free_list");
 253       }
 254       res = new_region_try_secondary_free_list(is_old);
 255       if (res != NULL) {
 256         return res;
 257       }
 258     }
 259   }
 260 
 261   res = _hrm.allocate_free_region(is_old);
 262 
 263   if (res == NULL) {
 264     if (G1ConcRegionFreeingVerbose) {
 265       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 266                              "res == NULL, trying the secondary_free_list");
 267     }
 268     res = new_region_try_secondary_free_list(is_old);
 269   }
 270   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 271     // Currently, only attempts to allocate GC alloc regions set
 272     // do_expand to true. So, we should only reach here during a
 273     // safepoint. If this assumption changes we might have to
 274     // reconsider the use of _expand_heap_after_alloc_failure.
 275     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 276 
 277     ergo_verbose1(ErgoHeapSizing,
 278                   "attempt heap expansion",
 279                   ergo_format_reason("region allocation request failed")
 280                   ergo_format_byte("allocation request"),
 281                   word_size * HeapWordSize);
 282     if (expand(word_size * HeapWordSize)) {
 283       // Given that expand() succeeded in expanding the heap, and we
 284       // always expand the heap by an amount aligned to the heap
 285       // region size, the free list should in theory not be empty.
 286       // In either case allocate_free_region() will check for NULL.
 287       res = _hrm.allocate_free_region(is_old);
 288     } else {
 289       _expand_heap_after_alloc_failure = false;
 290     }
 291   }
 292   return res;
 293 }
 294 
 295 HeapWord*
 296 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 297                                                            uint num_regions,
 298                                                            size_t word_size,
 299                                                            AllocationContext_t context) {
 300   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 301   assert(is_humongous(word_size), "word_size should be humongous");
 302   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 303 
 304   // Index of last region in the series + 1.
 305   uint last = first + num_regions;
 306 
 307   // We need to initialize the region(s) we just discovered. This is
 308   // a bit tricky given that it can happen concurrently with
 309   // refinement threads refining cards on these regions and
 310   // potentially wanting to refine the BOT as they are scanning
 311   // those cards (this can happen shortly after a cleanup; see CR
 312   // 6991377). So we have to set up the region(s) carefully and in
 313   // a specific order.
 314 
 315   // The word size sum of all the regions we will allocate.
 316   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 317   assert(word_size <= word_size_sum, "sanity");
 318 
 319   // This will be the "starts humongous" region.
 320   HeapRegion* first_hr = region_at(first);
 321   // The header of the new object will be placed at the bottom of
 322   // the first region.
 323   HeapWord* new_obj = first_hr->bottom();
 324   // This will be the new top of the new object.
 325   HeapWord* obj_top = new_obj + word_size;
 326 
 327   // First, we need to zero the header of the space that we will be
 328   // allocating. When we update top further down, some refinement
 329   // threads might try to scan the region. By zeroing the header we
 330   // ensure that any thread that will try to scan the region will
 331   // come across the zero klass word and bail out.
 332   //
 333   // NOTE: It would not have been correct to have used
 334   // CollectedHeap::fill_with_object() and make the space look like
 335   // an int array. The thread that is doing the allocation will
 336   // later update the object header to a potentially different array
 337   // type and, for a very short period of time, the klass and length
 338   // fields will be inconsistent. This could cause a refinement
 339   // thread to calculate the object size incorrectly.
 340   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 341 
 342   size_t fill_size = word_size_sum - word_size;
 343   if (fill_size >= min_fill_size()) {
 344     fill_with_objects(obj_top, fill_size);
 345   } else {
 346     fill_size = 0;







 347   }
 348 
 349   // We will set up the first region as "starts humongous". This
 350   // will also update the BOT covering all the regions to reflect
 351   // that there is a single object that starts at the bottom of the
 352   // first region.
 353   first_hr->set_starts_humongous(obj_top, fill_size);
 354   first_hr->set_allocation_context(context);
 355   // Then, if there are any, we will set up the "continues
 356   // humongous" regions.
 357   HeapRegion* hr = NULL;
 358   for (uint i = first + 1; i < last; ++i) {
 359     hr = region_at(i);
 360     hr->set_continues_humongous(first_hr);
 361     hr->set_allocation_context(context);
 362   }
 363 
 364   // Up to this point no concurrent thread would have been able to
 365   // do any scanning on any region in this series. All the top
 366   // fields still point to bottom, so the intersection between
 367   // [bottom,top] and [card_start,card_end] will be empty. Before we
 368   // update the top fields, we'll do a storestore to make sure that
 369   // no thread sees the update to top before the zeroing of the
 370   // object header and the BOT initialization.
 371   OrderAccess::storestore();
 372 
 373   // Now that the BOT and the object header have been initialized,
 374   // we can update top of the "starts humongous" region.
 375   first_hr->set_top(first_hr->end());
 376   if (_hr_printer.is_active()) {
 377     _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, first_hr->end());
 378   }
 379 
 380   // Now, we will update the top fields of the "continues humongous"
 381   // regions.
 382   hr = NULL;
 383   for (uint i = first + 1; i < last; ++i) {
 384     hr = region_at(i);
 385     hr->set_top(hr->end());
 386     if (_hr_printer.is_active()) {
 387       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 388     }
 389   }
 390 
 391   assert(hr == NULL || (hr->bottom() < obj_top && obj_top <= hr->end()),






 392          "obj_top should be in last region");
 393 
 394   check_bitmaps("Humongous Region Allocation", first_hr);
 395 
 396   increase_used(word_size_sum * HeapWordSize);


 397 
 398   for (uint i = first; i < last; ++i) {
 399     _humongous_set.add(region_at(i));








 400   }
 401 
 402   return new_obj;
 403 }
 404 
 405 // If could fit into free regions w/o expansion, try.
 406 // Otherwise, if can expand, do so.
 407 // Otherwise, if using ex regions might help, try with ex given back.
 408 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 409   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 410 
 411   verify_region_sets_optional();
 412 
 413   uint first = G1_NO_HRM_INDEX;
 414   uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
 415 
 416   if (obj_regions == 1) {
 417     // Only one region to allocate, try to use a fast path by directly allocating
 418     // from the free lists. Do not try to expand here, we will potentially do that
 419     // later.
 420     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 421     if (hr != NULL) {
 422       first = hr->hrm_index();
 423     }
 424   } else {
 425     // We can't allocate humongous regions spanning more than one region while
 426     // cleanupComplete() is running, since some of the regions we find to be
 427     // empty might not yet be added to the free list. It is not straightforward
 428     // to know in which list they are on so that we can remove them. We only
 429     // need to do this if we need to allocate more than one region to satisfy the
 430     // current humongous allocation request. If we are only allocating one region
 431     // we use the one-region region allocation code (see above), that already
 432     // potentially waits for regions from the secondary free list.
 433     wait_while_free_regions_coming();
 434     append_secondary_free_list_if_not_empty_with_lock();
 435 
 436     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 437     // are lucky enough to find some.
 438     first = _hrm.find_contiguous_only_empty(obj_regions);
 439     if (first != G1_NO_HRM_INDEX) {
 440       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 441     }
 442   }
 443 
 444   if (first == G1_NO_HRM_INDEX) {
 445     // Policy: We could not find enough regions for the humongous object in the
 446     // free list. Look through the heap to find a mix of free and uncommitted regions.
 447     // If so, try expansion.
 448     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 449     if (first != G1_NO_HRM_INDEX) {
 450       // We found something. Make sure these regions are committed, i.e. expand
 451       // the heap. Alternatively we could do a defragmentation GC.
 452       ergo_verbose1(ErgoHeapSizing,
 453                     "attempt heap expansion",
 454                     ergo_format_reason("humongous allocation request failed")
 455                     ergo_format_byte("allocation request"),
 456                     word_size * HeapWordSize);
 457 
 458       _hrm.expand_at(first, obj_regions);
 459       g1_policy()->record_new_heap_size(num_regions());
 460 
 461 #ifdef ASSERT
 462       for (uint i = first; i < first + obj_regions; ++i) {
 463         HeapRegion* hr = region_at(i);
 464         assert(hr->is_free(), "sanity");
 465         assert(hr->is_empty(), "sanity");
 466         assert(is_on_master_free_list(hr), "sanity");
 467       }
 468 #endif
 469       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 470     } else {
 471       // Policy: Potentially trigger a defragmentation GC.
 472     }
 473   }
 474 
 475   HeapWord* result = NULL;
 476   if (first != G1_NO_HRM_INDEX) {
 477     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 478                                                        word_size, context);
 479     assert(result != NULL, "it should always return a valid result");
 480 
 481     // A successful humongous object allocation changes the used space
 482     // information of the old generation so we need to recalculate the
 483     // sizes and update the jstat counters here.
 484     g1mm()->update_sizes();
 485   }
 486 
 487   verify_region_sets_optional();
 488 
 489   return result;
 490 }
 491 
 492 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 493   assert_heap_not_locked_and_not_at_safepoint();
 494   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 495 
 496   uint dummy_gc_count_before;
 497   uint dummy_gclocker_retry_count = 0;
 498   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 499 }
 500 
 501 HeapWord*
 502 G1CollectedHeap::mem_allocate(size_t word_size,
 503                               bool*  gc_overhead_limit_was_exceeded) {
 504   assert_heap_not_locked_and_not_at_safepoint();
 505 
 506   // Loop until the allocation is satisfied, or unsatisfied after GC.
 507   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 508     uint gc_count_before;
 509 
 510     HeapWord* result = NULL;
 511     if (!is_humongous(word_size)) {
 512       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 513     } else {
 514       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 515     }
 516     if (result != NULL) {
 517       return result;
 518     }
 519 
 520     // Create the garbage collection operation...
 521     VM_G1CollectForAllocation op(gc_count_before, word_size);
 522     op.set_allocation_context(AllocationContext::current());
 523 
 524     // ...and get the VM thread to execute it.
 525     VMThread::execute(&op);
 526 
 527     if (op.prologue_succeeded() && op.pause_succeeded()) {
 528       // If the operation was successful we'll return the result even
 529       // if it is NULL. If the allocation attempt failed immediately
 530       // after a Full GC, it's unlikely we'll be able to allocate now.
 531       HeapWord* result = op.result();
 532       if (result != NULL && !is_humongous(word_size)) {
 533         // Allocations that take place on VM operations do not do any
 534         // card dirtying and we have to do it here. We only have to do
 535         // this for non-humongous allocations, though.
 536         dirty_young_block(result, word_size);
 537       }
 538       return result;
 539     } else {
 540       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 541         return NULL;
 542       }
 543       assert(op.result() == NULL,
 544              "the result should be NULL if the VM op did not succeed");
 545     }
 546 
 547     // Give a warning if we seem to be looping forever.
 548     if ((QueuedAllocationWarningCount > 0) &&
 549         (try_count % QueuedAllocationWarningCount == 0)) {
 550       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 551     }
 552   }
 553 
 554   ShouldNotReachHere();
 555   return NULL;
 556 }
 557 
 558 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 559                                                    AllocationContext_t context,
 560                                                    uint* gc_count_before_ret,
 561                                                    uint* gclocker_retry_count_ret) {
 562   // Make sure you read the note in attempt_allocation_humongous().
 563 
 564   assert_heap_not_locked_and_not_at_safepoint();
 565   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 566          "be called for humongous allocation requests");
 567 
 568   // We should only get here after the first-level allocation attempt
 569   // (attempt_allocation()) failed to allocate.
 570 
 571   // We will loop until a) we manage to successfully perform the
 572   // allocation or b) we successfully schedule a collection which
 573   // fails to perform the allocation. b) is the only case when we'll
 574   // return NULL.
 575   HeapWord* result = NULL;
 576   for (int try_count = 1; /* we'll return */; try_count += 1) {
 577     bool should_try_gc;
 578     uint gc_count_before;
 579 
 580     {
 581       MutexLockerEx x(Heap_lock);
 582       result = _allocator->attempt_allocation_locked(word_size, context);
 583       if (result != NULL) {
 584         return result;
 585       }
 586 
 587       if (GC_locker::is_active_and_needs_gc()) {
 588         if (g1_policy()->can_expand_young_list()) {
 589           // No need for an ergo verbose message here,
 590           // can_expand_young_list() does this when it returns true.
 591           result = _allocator->attempt_allocation_force(word_size, context);
 592           if (result != NULL) {
 593             return result;
 594           }
 595         }
 596         should_try_gc = false;
 597       } else {
 598         // The GCLocker may not be active but the GCLocker initiated
 599         // GC may not yet have been performed (GCLocker::needs_gc()
 600         // returns true). In this case we do not try this GC and
 601         // wait until the GCLocker initiated GC is performed, and
 602         // then retry the allocation.
 603         if (GC_locker::needs_gc()) {
 604           should_try_gc = false;
 605         } else {
 606           // Read the GC count while still holding the Heap_lock.
 607           gc_count_before = total_collections();
 608           should_try_gc = true;
 609         }
 610       }
 611     }
 612 
 613     if (should_try_gc) {
 614       bool succeeded;
 615       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 616                                    GCCause::_g1_inc_collection_pause);
 617       if (result != NULL) {
 618         assert(succeeded, "only way to get back a non-NULL result");
 619         return result;
 620       }
 621 
 622       if (succeeded) {
 623         // If we get here we successfully scheduled a collection which
 624         // failed to allocate. No point in trying to allocate
 625         // further. We'll just return NULL.
 626         MutexLockerEx x(Heap_lock);
 627         *gc_count_before_ret = total_collections();
 628         return NULL;
 629       }
 630     } else {
 631       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 632         MutexLockerEx x(Heap_lock);
 633         *gc_count_before_ret = total_collections();
 634         return NULL;
 635       }
 636       // The GCLocker is either active or the GCLocker initiated
 637       // GC has not yet been performed. Stall until it is and
 638       // then retry the allocation.
 639       GC_locker::stall_until_clear();
 640       (*gclocker_retry_count_ret) += 1;
 641     }
 642 
 643     // We can reach here if we were unsuccessful in scheduling a
 644     // collection (because another thread beat us to it) or if we were
 645     // stalled due to the GC locker. In either can we should retry the
 646     // allocation attempt in case another thread successfully
 647     // performed a collection and reclaimed enough space. We do the
 648     // first attempt (without holding the Heap_lock) here and the
 649     // follow-on attempt will be at the start of the next loop
 650     // iteration (after taking the Heap_lock).
 651     result = _allocator->attempt_allocation(word_size, context);
 652     if (result != NULL) {
 653       return result;
 654     }
 655 
 656     // Give a warning if we seem to be looping forever.
 657     if ((QueuedAllocationWarningCount > 0) &&
 658         (try_count % QueuedAllocationWarningCount == 0)) {
 659       warning("G1CollectedHeap::attempt_allocation_slow() "
 660               "retries %d times", try_count);
 661     }
 662   }
 663 
 664   ShouldNotReachHere();
 665   return NULL;
 666 }
 667 
 668 void G1CollectedHeap::begin_archive_alloc_range() {
 669   assert_at_safepoint(true /* should_be_vm_thread */);
 670   if (_archive_allocator == NULL) {
 671     _archive_allocator = G1ArchiveAllocator::create_allocator(this);
 672   }
 673 }
 674 
 675 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 676   // Allocations in archive regions cannot be of a size that would be considered
 677   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 678   // may be different at archive-restore time.
 679   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 680 }
 681 
 682 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 683   assert_at_safepoint(true /* should_be_vm_thread */);
 684   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 685   if (is_archive_alloc_too_large(word_size)) {
 686     return NULL;
 687   }
 688   return _archive_allocator->archive_mem_allocate(word_size);
 689 }
 690 
 691 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 692                                               size_t end_alignment_in_bytes) {
 693   assert_at_safepoint(true /* should_be_vm_thread */);
 694   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 695 
 696   // Call complete_archive to do the real work, filling in the MemRegion
 697   // array with the archive regions.
 698   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 699   delete _archive_allocator;
 700   _archive_allocator = NULL;
 701 }
 702 
 703 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 704   assert(ranges != NULL, "MemRegion array NULL");
 705   assert(count != 0, "No MemRegions provided");
 706   MemRegion reserved = _hrm.reserved();
 707   for (size_t i = 0; i < count; i++) {
 708     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 709       return false;
 710     }
 711   }
 712   return true;
 713 }
 714 
 715 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
 716   assert(!is_init_completed(), "Expect to be called at JVM init time");
 717   assert(ranges != NULL, "MemRegion array NULL");
 718   assert(count != 0, "No MemRegions provided");
 719   MutexLockerEx x(Heap_lock);
 720 
 721   MemRegion reserved = _hrm.reserved();
 722   HeapWord* prev_last_addr = NULL;
 723   HeapRegion* prev_last_region = NULL;
 724 
 725   // Temporarily disable pretouching of heap pages. This interface is used
 726   // when mmap'ing archived heap data in, so pre-touching is wasted.
 727   FlagSetting fs(AlwaysPreTouch, false);
 728 
 729   // Enable archive object checking in G1MarkSweep. We have to let it know
 730   // about each archive range, so that objects in those ranges aren't marked.
 731   G1MarkSweep::enable_archive_object_check();
 732 
 733   // For each specified MemRegion range, allocate the corresponding G1
 734   // regions and mark them as archive regions. We expect the ranges in
 735   // ascending starting address order, without overlap.
 736   for (size_t i = 0; i < count; i++) {
 737     MemRegion curr_range = ranges[i];
 738     HeapWord* start_address = curr_range.start();
 739     size_t word_size = curr_range.word_size();
 740     HeapWord* last_address = curr_range.last();
 741     size_t commits = 0;
 742 
 743     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 744               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 745               p2i(start_address), p2i(last_address));
 746     guarantee(start_address > prev_last_addr,
 747               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 748               p2i(start_address), p2i(prev_last_addr));
 749     prev_last_addr = last_address;
 750 
 751     // Check for ranges that start in the same G1 region in which the previous
 752     // range ended, and adjust the start address so we don't try to allocate
 753     // the same region again. If the current range is entirely within that
 754     // region, skip it, just adjusting the recorded top.
 755     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 756     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 757       start_address = start_region->end();
 758       if (start_address > last_address) {
 759         increase_used(word_size * HeapWordSize);
 760         start_region->set_top(last_address + 1);
 761         continue;
 762       }
 763       start_region->set_top(start_address);
 764       curr_range = MemRegion(start_address, last_address + 1);
 765       start_region = _hrm.addr_to_region(start_address);
 766     }
 767 
 768     // Perform the actual region allocation, exiting if it fails.
 769     // Then note how much new space we have allocated.
 770     if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
 771       return false;
 772     }
 773     increase_used(word_size * HeapWordSize);
 774     if (commits != 0) {
 775       ergo_verbose1(ErgoHeapSizing,
 776                     "attempt heap expansion",
 777                     ergo_format_reason("allocate archive regions")
 778                     ergo_format_byte("total size"),
 779                     HeapRegion::GrainWords * HeapWordSize * commits);
 780     }
 781 
 782     // Mark each G1 region touched by the range as archive, add it to the old set,
 783     // and set the allocation context and top.
 784     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 785     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 786     prev_last_region = last_region;
 787 
 788     while (curr_region != NULL) {
 789       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 790              "Region already in use (index %u)", curr_region->hrm_index());
 791       _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
 792       curr_region->set_allocation_context(AllocationContext::system());
 793       curr_region->set_archive();
 794       _old_set.add(curr_region);
 795       if (curr_region != last_region) {
 796         curr_region->set_top(curr_region->end());
 797         curr_region = _hrm.next_region_in_heap(curr_region);
 798       } else {
 799         curr_region->set_top(last_address + 1);
 800         curr_region = NULL;
 801       }
 802     }
 803 
 804     // Notify mark-sweep of the archive range.
 805     G1MarkSweep::set_range_archive(curr_range, true);
 806   }
 807   return true;
 808 }
 809 
 810 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 811   assert(!is_init_completed(), "Expect to be called at JVM init time");
 812   assert(ranges != NULL, "MemRegion array NULL");
 813   assert(count != 0, "No MemRegions provided");
 814   MemRegion reserved = _hrm.reserved();
 815   HeapWord *prev_last_addr = NULL;
 816   HeapRegion* prev_last_region = NULL;
 817 
 818   // For each MemRegion, create filler objects, if needed, in the G1 regions
 819   // that contain the address range. The address range actually within the
 820   // MemRegion will not be modified. That is assumed to have been initialized
 821   // elsewhere, probably via an mmap of archived heap data.
 822   MutexLockerEx x(Heap_lock);
 823   for (size_t i = 0; i < count; i++) {
 824     HeapWord* start_address = ranges[i].start();
 825     HeapWord* last_address = ranges[i].last();
 826 
 827     assert(reserved.contains(start_address) && reserved.contains(last_address),
 828            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 829            p2i(start_address), p2i(last_address));
 830     assert(start_address > prev_last_addr,
 831            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 832            p2i(start_address), p2i(prev_last_addr));
 833 
 834     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 835     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 836     HeapWord* bottom_address = start_region->bottom();
 837 
 838     // Check for a range beginning in the same region in which the
 839     // previous one ended.
 840     if (start_region == prev_last_region) {
 841       bottom_address = prev_last_addr + 1;
 842     }
 843 
 844     // Verify that the regions were all marked as archive regions by
 845     // alloc_archive_regions.
 846     HeapRegion* curr_region = start_region;
 847     while (curr_region != NULL) {
 848       guarantee(curr_region->is_archive(),
 849                 "Expected archive region at index %u", curr_region->hrm_index());
 850       if (curr_region != last_region) {
 851         curr_region = _hrm.next_region_in_heap(curr_region);
 852       } else {
 853         curr_region = NULL;
 854       }
 855     }
 856 
 857     prev_last_addr = last_address;
 858     prev_last_region = last_region;
 859 
 860     // Fill the memory below the allocated range with dummy object(s),
 861     // if the region bottom does not match the range start, or if the previous
 862     // range ended within the same G1 region, and there is a gap.
 863     if (start_address != bottom_address) {
 864       size_t fill_size = pointer_delta(start_address, bottom_address);
 865       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 866       increase_used(fill_size * HeapWordSize);
 867     }
 868   }
 869 }
 870 
 871 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
 872                                                      uint* gc_count_before_ret,
 873                                                      uint* gclocker_retry_count_ret) {
 874   assert_heap_not_locked_and_not_at_safepoint();
 875   assert(!is_humongous(word_size), "attempt_allocation() should not "
 876          "be called for humongous allocation requests");
 877 
 878   AllocationContext_t context = AllocationContext::current();
 879   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 880 
 881   if (result == NULL) {
 882     result = attempt_allocation_slow(word_size,
 883                                      context,
 884                                      gc_count_before_ret,
 885                                      gclocker_retry_count_ret);
 886   }
 887   assert_heap_not_locked();
 888   if (result != NULL) {
 889     dirty_young_block(result, word_size);
 890   }
 891   return result;
 892 }
 893 
 894 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 895   assert(!is_init_completed(), "Expect to be called at JVM init time");
 896   assert(ranges != NULL, "MemRegion array NULL");
 897   assert(count != 0, "No MemRegions provided");
 898   MemRegion reserved = _hrm.reserved();
 899   HeapWord* prev_last_addr = NULL;
 900   HeapRegion* prev_last_region = NULL;
 901   size_t size_used = 0;
 902   size_t uncommitted_regions = 0;
 903 
 904   // For each Memregion, free the G1 regions that constitute it, and
 905   // notify mark-sweep that the range is no longer to be considered 'archive.'
 906   MutexLockerEx x(Heap_lock);
 907   for (size_t i = 0; i < count; i++) {
 908     HeapWord* start_address = ranges[i].start();
 909     HeapWord* last_address = ranges[i].last();
 910 
 911     assert(reserved.contains(start_address) && reserved.contains(last_address),
 912            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 913            p2i(start_address), p2i(last_address));
 914     assert(start_address > prev_last_addr,
 915            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 916            p2i(start_address), p2i(prev_last_addr));
 917     size_used += ranges[i].byte_size();
 918     prev_last_addr = last_address;
 919 
 920     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 921     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 922 
 923     // Check for ranges that start in the same G1 region in which the previous
 924     // range ended, and adjust the start address so we don't try to free
 925     // the same region again. If the current range is entirely within that
 926     // region, skip it.
 927     if (start_region == prev_last_region) {
 928       start_address = start_region->end();
 929       if (start_address > last_address) {
 930         continue;
 931       }
 932       start_region = _hrm.addr_to_region(start_address);
 933     }
 934     prev_last_region = last_region;
 935 
 936     // After verifying that each region was marked as an archive region by
 937     // alloc_archive_regions, set it free and empty and uncommit it.
 938     HeapRegion* curr_region = start_region;
 939     while (curr_region != NULL) {
 940       guarantee(curr_region->is_archive(),
 941                 "Expected archive region at index %u", curr_region->hrm_index());
 942       uint curr_index = curr_region->hrm_index();
 943       _old_set.remove(curr_region);
 944       curr_region->set_free();
 945       curr_region->set_top(curr_region->bottom());
 946       if (curr_region != last_region) {
 947         curr_region = _hrm.next_region_in_heap(curr_region);
 948       } else {
 949         curr_region = NULL;
 950       }
 951       _hrm.shrink_at(curr_index, 1);
 952       uncommitted_regions++;
 953     }
 954 
 955     // Notify mark-sweep that this is no longer an archive range.
 956     G1MarkSweep::set_range_archive(ranges[i], false);
 957   }
 958 
 959   if (uncommitted_regions != 0) {
 960     ergo_verbose1(ErgoHeapSizing,
 961                   "attempt heap shrinking",
 962                   ergo_format_reason("uncommitted archive regions")
 963                   ergo_format_byte("total size"),
 964                   HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 965   }
 966   decrease_used(size_used);
 967 }
 968 
 969 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 970                                                         uint* gc_count_before_ret,
 971                                                         uint* gclocker_retry_count_ret) {
 972   // The structure of this method has a lot of similarities to
 973   // attempt_allocation_slow(). The reason these two were not merged
 974   // into a single one is that such a method would require several "if
 975   // allocation is not humongous do this, otherwise do that"
 976   // conditional paths which would obscure its flow. In fact, an early
 977   // version of this code did use a unified method which was harder to
 978   // follow and, as a result, it had subtle bugs that were hard to
 979   // track down. So keeping these two methods separate allows each to
 980   // be more readable. It will be good to keep these two in sync as
 981   // much as possible.
 982 
 983   assert_heap_not_locked_and_not_at_safepoint();
 984   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 985          "should only be called for humongous allocations");
 986 
 987   // Humongous objects can exhaust the heap quickly, so we should check if we
 988   // need to start a marking cycle at each humongous object allocation. We do
 989   // the check before we do the actual allocation. The reason for doing it
 990   // before the allocation is that we avoid having to keep track of the newly
 991   // allocated memory while we do a GC.
 992   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 993                                            word_size)) {
 994     collect(GCCause::_g1_humongous_allocation);
 995   }
 996 
 997   // We will loop until a) we manage to successfully perform the
 998   // allocation or b) we successfully schedule a collection which
 999   // fails to perform the allocation. b) is the only case when we'll
1000   // return NULL.
1001   HeapWord* result = NULL;
1002   for (int try_count = 1; /* we'll return */; try_count += 1) {
1003     bool should_try_gc;
1004     uint gc_count_before;
1005 
1006     {
1007       MutexLockerEx x(Heap_lock);
1008 
1009       // Given that humongous objects are not allocated in young
1010       // regions, we'll first try to do the allocation without doing a
1011       // collection hoping that there's enough space in the heap.
1012       result = humongous_obj_allocate(word_size, AllocationContext::current());
1013       if (result != NULL) {
1014         return result;
1015       }
1016 
1017       if (GC_locker::is_active_and_needs_gc()) {
1018         should_try_gc = false;
1019       } else {
1020          // The GCLocker may not be active but the GCLocker initiated
1021         // GC may not yet have been performed (GCLocker::needs_gc()
1022         // returns true). In this case we do not try this GC and
1023         // wait until the GCLocker initiated GC is performed, and
1024         // then retry the allocation.
1025         if (GC_locker::needs_gc()) {
1026           should_try_gc = false;
1027         } else {
1028           // Read the GC count while still holding the Heap_lock.
1029           gc_count_before = total_collections();
1030           should_try_gc = true;
1031         }
1032       }
1033     }
1034 
1035     if (should_try_gc) {
1036       // If we failed to allocate the humongous object, we should try to
1037       // do a collection pause (if we're allowed) in case it reclaims
1038       // enough space for the allocation to succeed after the pause.
1039 
1040       bool succeeded;
1041       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1042                                    GCCause::_g1_humongous_allocation);
1043       if (result != NULL) {
1044         assert(succeeded, "only way to get back a non-NULL result");
1045         return result;
1046       }
1047 
1048       if (succeeded) {
1049         // If we get here we successfully scheduled a collection which
1050         // failed to allocate. No point in trying to allocate
1051         // further. We'll just return NULL.
1052         MutexLockerEx x(Heap_lock);
1053         *gc_count_before_ret = total_collections();
1054         return NULL;
1055       }
1056     } else {
1057       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1058         MutexLockerEx x(Heap_lock);
1059         *gc_count_before_ret = total_collections();
1060         return NULL;
1061       }
1062       // The GCLocker is either active or the GCLocker initiated
1063       // GC has not yet been performed. Stall until it is and
1064       // then retry the allocation.
1065       GC_locker::stall_until_clear();
1066       (*gclocker_retry_count_ret) += 1;
1067     }
1068 
1069     // We can reach here if we were unsuccessful in scheduling a
1070     // collection (because another thread beat us to it) or if we were
1071     // stalled due to the GC locker. In either can we should retry the
1072     // allocation attempt in case another thread successfully
1073     // performed a collection and reclaimed enough space.  Give a
1074     // warning if we seem to be looping forever.
1075 
1076     if ((QueuedAllocationWarningCount > 0) &&
1077         (try_count % QueuedAllocationWarningCount == 0)) {
1078       warning("G1CollectedHeap::attempt_allocation_humongous() "
1079               "retries %d times", try_count);
1080     }
1081   }
1082 
1083   ShouldNotReachHere();
1084   return NULL;
1085 }
1086 
1087 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1088                                                            AllocationContext_t context,
1089                                                            bool expect_null_mutator_alloc_region) {
1090   assert_at_safepoint(true /* should_be_vm_thread */);
1091   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1092          "the current alloc region was unexpectedly found to be non-NULL");
1093 
1094   if (!is_humongous(word_size)) {
1095     return _allocator->attempt_allocation_locked(word_size, context);
1096   } else {
1097     HeapWord* result = humongous_obj_allocate(word_size, context);
1098     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1099       collector_state()->set_initiate_conc_mark_if_possible(true);
1100     }
1101     return result;
1102   }
1103 
1104   ShouldNotReachHere();
1105 }
1106 
1107 class PostMCRemSetClearClosure: public HeapRegionClosure {
1108   G1CollectedHeap* _g1h;
1109   ModRefBarrierSet* _mr_bs;
1110 public:
1111   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1112     _g1h(g1h), _mr_bs(mr_bs) {}
1113 
1114   bool doHeapRegion(HeapRegion* r) {
1115     HeapRegionRemSet* hrrs = r->rem_set();
1116 
1117     _g1h->reset_gc_time_stamps(r);
1118 
1119     if (r->is_continues_humongous()) {
1120       // We'll assert that the strong code root list and RSet is empty
1121       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1122       assert(hrrs->occupied() == 0, "RSet should be empty");
1123     } else {
1124       hrrs->clear();
1125     }
1126     // You might think here that we could clear just the cards
1127     // corresponding to the used region.  But no: if we leave a dirty card
1128     // in a region we might allocate into, then it would prevent that card
1129     // from being enqueued, and cause it to be missed.
1130     // Re: the performance cost: we shouldn't be doing full GC anyway!
1131     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1132 
1133     return false;
1134   }
1135 };
1136 
1137 void G1CollectedHeap::clear_rsets_post_compaction() {
1138   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1139   heap_region_iterate(&rs_clear);
1140 }
1141 
1142 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1143   G1CollectedHeap*   _g1h;
1144   UpdateRSOopClosure _cl;
1145 public:
1146   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1147     _cl(g1->g1_rem_set(), worker_i),
1148     _g1h(g1)
1149   { }
1150 
1151   bool doHeapRegion(HeapRegion* r) {
1152     if (!r->is_continues_humongous()) {
1153       _cl.set_from(r);
1154       r->oop_iterate(&_cl);
1155     }
1156     return false;
1157   }
1158 };
1159 
1160 class ParRebuildRSTask: public AbstractGangTask {
1161   G1CollectedHeap* _g1;
1162   HeapRegionClaimer _hrclaimer;
1163 
1164 public:
1165   ParRebuildRSTask(G1CollectedHeap* g1) :
1166       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1167 
1168   void work(uint worker_id) {
1169     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1170     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1171   }
1172 };
1173 
1174 class PostCompactionPrinterClosure: public HeapRegionClosure {
1175 private:
1176   G1HRPrinter* _hr_printer;
1177 public:
1178   bool doHeapRegion(HeapRegion* hr) {
1179     assert(!hr->is_young(), "not expecting to find young regions");
1180     if (hr->is_free()) {
1181       // We only generate output for non-empty regions.
1182     } else if (hr->is_starts_humongous()) {
1183       _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1184     } else if (hr->is_continues_humongous()) {
1185       _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1186     } else if (hr->is_archive()) {
1187       _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1188     } else if (hr->is_old()) {
1189       _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1190     } else {
1191       ShouldNotReachHere();
1192     }
1193     return false;
1194   }
1195 
1196   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1197     : _hr_printer(hr_printer) { }
1198 };
1199 
1200 void G1CollectedHeap::print_hrm_post_compaction() {
1201   PostCompactionPrinterClosure cl(hr_printer());
1202   heap_region_iterate(&cl);
1203 }
1204 
1205 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1206                                          bool clear_all_soft_refs) {
1207   assert_at_safepoint(true /* should_be_vm_thread */);
1208 
1209   if (GC_locker::check_active_before_gc()) {
1210     return false;
1211   }
1212 
1213   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1214   gc_timer->register_gc_start();
1215 
1216   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1217   GCIdMark gc_id_mark;
1218   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1219 
1220   SvcGCMarker sgcm(SvcGCMarker::FULL);
1221   ResourceMark rm;
1222 
1223   G1Log::update_level();
1224   print_heap_before_gc();
1225   trace_heap_before_gc(gc_tracer);
1226 
1227   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1228 
1229   verify_region_sets_optional();
1230 
1231   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1232                            collector_policy()->should_clear_all_soft_refs();
1233 
1234   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1235 
1236   {
1237     IsGCActiveMark x;
1238 
1239     // Timing
1240     assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1241     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1242 
1243     {
1244       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1245       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1246       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1247 
1248       g1_policy()->record_full_collection_start();
1249 
1250       // Note: When we have a more flexible GC logging framework that
1251       // allows us to add optional attributes to a GC log record we
1252       // could consider timing and reporting how long we wait in the
1253       // following two methods.
1254       wait_while_free_regions_coming();
1255       // If we start the compaction before the CM threads finish
1256       // scanning the root regions we might trip them over as we'll
1257       // be moving objects / updating references. So let's wait until
1258       // they are done. By telling them to abort, they should complete
1259       // early.
1260       _cm->root_regions()->abort();
1261       _cm->root_regions()->wait_until_scan_finished();
1262       append_secondary_free_list_if_not_empty_with_lock();
1263 
1264       gc_prologue(true);
1265       increment_total_collections(true /* full gc */);
1266       increment_old_marking_cycles_started();
1267 
1268       assert(used() == recalculate_used(), "Should be equal");
1269 
1270       verify_before_gc();
1271 
1272       check_bitmaps("Full GC Start");
1273       pre_full_gc_dump(gc_timer);
1274 
1275 #if defined(COMPILER2) || INCLUDE_JVMCI
1276       DerivedPointerTable::clear();
1277 #endif
1278 
1279       // Disable discovery and empty the discovered lists
1280       // for the CM ref processor.
1281       ref_processor_cm()->disable_discovery();
1282       ref_processor_cm()->abandon_partial_discovery();
1283       ref_processor_cm()->verify_no_references_recorded();
1284 
1285       // Abandon current iterations of concurrent marking and concurrent
1286       // refinement, if any are in progress. We have to do this before
1287       // wait_until_scan_finished() below.
1288       concurrent_mark()->abort();
1289 
1290       // Make sure we'll choose a new allocation region afterwards.
1291       _allocator->release_mutator_alloc_region();
1292       _allocator->abandon_gc_alloc_regions();
1293       g1_rem_set()->cleanupHRRS();
1294 
1295       // We should call this after we retire any currently active alloc
1296       // regions so that all the ALLOC / RETIRE events are generated
1297       // before the start GC event.
1298       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1299 
1300       // We may have added regions to the current incremental collection
1301       // set between the last GC or pause and now. We need to clear the
1302       // incremental collection set and then start rebuilding it afresh
1303       // after this full GC.
1304       abandon_collection_set(g1_policy()->inc_cset_head());
1305       g1_policy()->clear_incremental_cset();
1306       g1_policy()->stop_incremental_cset_building();
1307 
1308       tear_down_region_sets(false /* free_list_only */);
1309       collector_state()->set_gcs_are_young(true);
1310 
1311       // See the comments in g1CollectedHeap.hpp and
1312       // G1CollectedHeap::ref_processing_init() about
1313       // how reference processing currently works in G1.
1314 
1315       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1316       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1317 
1318       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1319       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1320 
1321       ref_processor_stw()->enable_discovery();
1322       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1323 
1324       // Do collection work
1325       {
1326         HandleMark hm;  // Discard invalid handles created during gc
1327         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1328       }
1329 
1330       assert(num_free_regions() == 0, "we should not have added any free regions");
1331       rebuild_region_sets(false /* free_list_only */);
1332 
1333       // Enqueue any discovered reference objects that have
1334       // not been removed from the discovered lists.
1335       ref_processor_stw()->enqueue_discovered_references();
1336 
1337 #if defined(COMPILER2) || INCLUDE_JVMCI
1338       DerivedPointerTable::update_pointers();
1339 #endif
1340 
1341       MemoryService::track_memory_usage();
1342 
1343       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1344       ref_processor_stw()->verify_no_references_recorded();
1345 
1346       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1347       ClassLoaderDataGraph::purge();
1348       MetaspaceAux::verify_metrics();
1349 
1350       // Note: since we've just done a full GC, concurrent
1351       // marking is no longer active. Therefore we need not
1352       // re-enable reference discovery for the CM ref processor.
1353       // That will be done at the start of the next marking cycle.
1354       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1355       ref_processor_cm()->verify_no_references_recorded();
1356 
1357       reset_gc_time_stamp();
1358       // Since everything potentially moved, we will clear all remembered
1359       // sets, and clear all cards.  Later we will rebuild remembered
1360       // sets. We will also reset the GC time stamps of the regions.
1361       clear_rsets_post_compaction();
1362       check_gc_time_stamps();
1363 
1364       resize_if_necessary_after_full_collection();
1365 
1366       if (_hr_printer.is_active()) {
1367         // We should do this after we potentially resize the heap so
1368         // that all the COMMIT / UNCOMMIT events are generated before
1369         // the end GC event.
1370 
1371         print_hrm_post_compaction();
1372         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1373       }
1374 
1375       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1376       if (hot_card_cache->use_cache()) {
1377         hot_card_cache->reset_card_counts();
1378         hot_card_cache->reset_hot_cache();
1379       }
1380 
1381       // Rebuild remembered sets of all regions.
1382       uint n_workers =
1383         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1384                                                 workers()->active_workers(),
1385                                                 Threads::number_of_non_daemon_threads());
1386       workers()->set_active_workers(n_workers);
1387 
1388       ParRebuildRSTask rebuild_rs_task(this);
1389       workers()->run_task(&rebuild_rs_task);
1390 
1391       // Rebuild the strong code root lists for each region
1392       rebuild_strong_code_roots();
1393 
1394       if (true) { // FIXME
1395         MetaspaceGC::compute_new_size();
1396       }
1397 
1398 #ifdef TRACESPINNING
1399       ParallelTaskTerminator::print_termination_counts();
1400 #endif
1401 
1402       // Discard all rset updates
1403       JavaThread::dirty_card_queue_set().abandon_logs();
1404       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1405 
1406       _young_list->reset_sampled_info();
1407       // At this point there should be no regions in the
1408       // entire heap tagged as young.
1409       assert(check_young_list_empty(true /* check_heap */),
1410              "young list should be empty at this point");
1411 
1412       // Update the number of full collections that have been completed.
1413       increment_old_marking_cycles_completed(false /* concurrent */);
1414 
1415       _hrm.verify_optional();
1416       verify_region_sets_optional();
1417 
1418       verify_after_gc();
1419 
1420       // Clear the previous marking bitmap, if needed for bitmap verification.
1421       // Note we cannot do this when we clear the next marking bitmap in
1422       // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1423       // objects marked during a full GC against the previous bitmap.
1424       // But we need to clear it before calling check_bitmaps below since
1425       // the full GC has compacted objects and updated TAMS but not updated
1426       // the prev bitmap.
1427       if (G1VerifyBitmaps) {
1428         ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1429       }
1430       check_bitmaps("Full GC End");
1431 
1432       // Start a new incremental collection set for the next pause
1433       assert(g1_policy()->collection_set() == NULL, "must be");
1434       g1_policy()->start_incremental_cset_building();
1435 
1436       clear_cset_fast_test();
1437 
1438       _allocator->init_mutator_alloc_region();
1439 
1440       g1_policy()->record_full_collection_end();
1441 
1442       if (G1Log::fine()) {
1443         g1_policy()->print_heap_transition();
1444       }
1445 
1446       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1447       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1448       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1449       // before any GC notifications are raised.
1450       g1mm()->update_sizes();
1451 
1452       gc_epilogue(true);
1453     }
1454 
1455     if (G1Log::finer()) {
1456       g1_policy()->print_detailed_heap_transition(true /* full */);
1457     }
1458 
1459     print_heap_after_gc();
1460     trace_heap_after_gc(gc_tracer);
1461 
1462     post_full_gc_dump(gc_timer);
1463 
1464     gc_timer->register_gc_end();
1465     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1466   }
1467 
1468   return true;
1469 }
1470 
1471 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1472   // Currently, there is no facility in the do_full_collection(bool) API to notify
1473   // the caller that the collection did not succeed (e.g., because it was locked
1474   // out by the GC locker). So, right now, we'll ignore the return value.
1475   bool dummy = do_full_collection(true,                /* explicit_gc */
1476                                   clear_all_soft_refs);
1477 }
1478 
1479 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1480   // Include bytes that will be pre-allocated to support collections, as "used".
1481   const size_t used_after_gc = used();
1482   const size_t capacity_after_gc = capacity();
1483   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1484 
1485   // This is enforced in arguments.cpp.
1486   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1487          "otherwise the code below doesn't make sense");
1488 
1489   // We don't have floating point command-line arguments
1490   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1491   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1492   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1493   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1494 
1495   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1496   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1497 
1498   // We have to be careful here as these two calculations can overflow
1499   // 32-bit size_t's.
1500   double used_after_gc_d = (double) used_after_gc;
1501   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1502   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1503 
1504   // Let's make sure that they are both under the max heap size, which
1505   // by default will make them fit into a size_t.
1506   double desired_capacity_upper_bound = (double) max_heap_size;
1507   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1508                                     desired_capacity_upper_bound);
1509   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1510                                     desired_capacity_upper_bound);
1511 
1512   // We can now safely turn them into size_t's.
1513   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1514   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1515 
1516   // This assert only makes sense here, before we adjust them
1517   // with respect to the min and max heap size.
1518   assert(minimum_desired_capacity <= maximum_desired_capacity,
1519          "minimum_desired_capacity = " SIZE_FORMAT ", "
1520          "maximum_desired_capacity = " SIZE_FORMAT,
1521          minimum_desired_capacity, maximum_desired_capacity);
1522 
1523   // Should not be greater than the heap max size. No need to adjust
1524   // it with respect to the heap min size as it's a lower bound (i.e.,
1525   // we'll try to make the capacity larger than it, not smaller).
1526   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1527   // Should not be less than the heap min size. No need to adjust it
1528   // with respect to the heap max size as it's an upper bound (i.e.,
1529   // we'll try to make the capacity smaller than it, not greater).
1530   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1531 
1532   if (capacity_after_gc < minimum_desired_capacity) {
1533     // Don't expand unless it's significant
1534     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1535     ergo_verbose4(ErgoHeapSizing,
1536                   "attempt heap expansion",
1537                   ergo_format_reason("capacity lower than "
1538                                      "min desired capacity after Full GC")
1539                   ergo_format_byte("capacity")
1540                   ergo_format_byte("occupancy")
1541                   ergo_format_byte_perc("min desired capacity"),
1542                   capacity_after_gc, used_after_gc,
1543                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1544     expand(expand_bytes);
1545 
1546     // No expansion, now see if we want to shrink
1547   } else if (capacity_after_gc > maximum_desired_capacity) {
1548     // Capacity too large, compute shrinking size
1549     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1550     ergo_verbose4(ErgoHeapSizing,
1551                   "attempt heap shrinking",
1552                   ergo_format_reason("capacity higher than "
1553                                      "max desired capacity after Full GC")
1554                   ergo_format_byte("capacity")
1555                   ergo_format_byte("occupancy")
1556                   ergo_format_byte_perc("max desired capacity"),
1557                   capacity_after_gc, used_after_gc,
1558                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1559     shrink(shrink_bytes);
1560   }
1561 }
1562 
1563 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1564                                                             AllocationContext_t context,
1565                                                             bool do_gc,
1566                                                             bool clear_all_soft_refs,
1567                                                             bool expect_null_mutator_alloc_region,
1568                                                             bool* gc_succeeded) {
1569   *gc_succeeded = true;
1570   // Let's attempt the allocation first.
1571   HeapWord* result =
1572     attempt_allocation_at_safepoint(word_size,
1573                                     context,
1574                                     expect_null_mutator_alloc_region);
1575   if (result != NULL) {
1576     assert(*gc_succeeded, "sanity");
1577     return result;
1578   }
1579 
1580   // In a G1 heap, we're supposed to keep allocation from failing by
1581   // incremental pauses.  Therefore, at least for now, we'll favor
1582   // expansion over collection.  (This might change in the future if we can
1583   // do something smarter than full collection to satisfy a failed alloc.)
1584   result = expand_and_allocate(word_size, context);
1585   if (result != NULL) {
1586     assert(*gc_succeeded, "sanity");
1587     return result;
1588   }
1589 
1590   if (do_gc) {
1591     // Expansion didn't work, we'll try to do a Full GC.
1592     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1593                                        clear_all_soft_refs);
1594   }
1595 
1596   return NULL;
1597 }
1598 
1599 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1600                                                      AllocationContext_t context,
1601                                                      bool* succeeded) {
1602   assert_at_safepoint(true /* should_be_vm_thread */);
1603 
1604   // Attempts to allocate followed by Full GC.
1605   HeapWord* result =
1606     satisfy_failed_allocation_helper(word_size,
1607                                      context,
1608                                      true,  /* do_gc */
1609                                      false, /* clear_all_soft_refs */
1610                                      false, /* expect_null_mutator_alloc_region */
1611                                      succeeded);
1612 
1613   if (result != NULL || !*succeeded) {
1614     return result;
1615   }
1616 
1617   // Attempts to allocate followed by Full GC that will collect all soft references.
1618   result = satisfy_failed_allocation_helper(word_size,
1619                                             context,
1620                                             true, /* do_gc */
1621                                             true, /* clear_all_soft_refs */
1622                                             true, /* expect_null_mutator_alloc_region */
1623                                             succeeded);
1624 
1625   if (result != NULL || !*succeeded) {
1626     return result;
1627   }
1628 
1629   // Attempts to allocate, no GC
1630   result = satisfy_failed_allocation_helper(word_size,
1631                                             context,
1632                                             false, /* do_gc */
1633                                             false, /* clear_all_soft_refs */
1634                                             true,  /* expect_null_mutator_alloc_region */
1635                                             succeeded);
1636 
1637   if (result != NULL) {
1638     assert(*succeeded, "sanity");
1639     return result;
1640   }
1641 
1642   assert(!collector_policy()->should_clear_all_soft_refs(),
1643          "Flag should have been handled and cleared prior to this point");
1644 
1645   // What else?  We might try synchronous finalization later.  If the total
1646   // space available is large enough for the allocation, then a more
1647   // complete compaction phase than we've tried so far might be
1648   // appropriate.
1649   assert(*succeeded, "sanity");
1650   return NULL;
1651 }
1652 
1653 // Attempting to expand the heap sufficiently
1654 // to support an allocation of the given "word_size".  If
1655 // successful, perform the allocation and return the address of the
1656 // allocated block, or else "NULL".
1657 
1658 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1659   assert_at_safepoint(true /* should_be_vm_thread */);
1660 
1661   verify_region_sets_optional();
1662 
1663   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1664   ergo_verbose1(ErgoHeapSizing,
1665                 "attempt heap expansion",
1666                 ergo_format_reason("allocation request failed")
1667                 ergo_format_byte("allocation request"),
1668                 word_size * HeapWordSize);
1669   if (expand(expand_bytes)) {
1670     _hrm.verify_optional();
1671     verify_region_sets_optional();
1672     return attempt_allocation_at_safepoint(word_size,
1673                                            context,
1674                                            false /* expect_null_mutator_alloc_region */);
1675   }
1676   return NULL;
1677 }
1678 
1679 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1680   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1681   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1682                                        HeapRegion::GrainBytes);
1683   ergo_verbose2(ErgoHeapSizing,
1684                 "expand the heap",
1685                 ergo_format_byte("requested expansion amount")
1686                 ergo_format_byte("attempted expansion amount"),
1687                 expand_bytes, aligned_expand_bytes);
1688 
1689   if (is_maximal_no_gc()) {
1690     ergo_verbose0(ErgoHeapSizing,
1691                       "did not expand the heap",
1692                       ergo_format_reason("heap already fully expanded"));
1693     return false;
1694   }
1695 
1696   double expand_heap_start_time_sec = os::elapsedTime();
1697   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1698   assert(regions_to_expand > 0, "Must expand by at least one region");
1699 
1700   uint expanded_by = _hrm.expand_by(regions_to_expand);
1701   if (expand_time_ms != NULL) {
1702     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1703   }
1704 
1705   if (expanded_by > 0) {
1706     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1707     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1708     g1_policy()->record_new_heap_size(num_regions());
1709   } else {
1710     ergo_verbose0(ErgoHeapSizing,
1711                   "did not expand the heap",
1712                   ergo_format_reason("heap expansion operation failed"));
1713     // The expansion of the virtual storage space was unsuccessful.
1714     // Let's see if it was because we ran out of swap.
1715     if (G1ExitOnExpansionFailure &&
1716         _hrm.available() >= regions_to_expand) {
1717       // We had head room...
1718       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1719     }
1720   }
1721   return regions_to_expand > 0;
1722 }
1723 
1724 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1725   size_t aligned_shrink_bytes =
1726     ReservedSpace::page_align_size_down(shrink_bytes);
1727   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1728                                          HeapRegion::GrainBytes);
1729   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1730 
1731   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1732   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1733 
1734   ergo_verbose3(ErgoHeapSizing,
1735                 "shrink the heap",
1736                 ergo_format_byte("requested shrinking amount")
1737                 ergo_format_byte("aligned shrinking amount")
1738                 ergo_format_byte("attempted shrinking amount"),
1739                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1740   if (num_regions_removed > 0) {
1741     g1_policy()->record_new_heap_size(num_regions());
1742   } else {
1743     ergo_verbose0(ErgoHeapSizing,
1744                   "did not shrink the heap",
1745                   ergo_format_reason("heap shrinking operation failed"));
1746   }
1747 }
1748 
1749 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1750   verify_region_sets_optional();
1751 
1752   // We should only reach here at the end of a Full GC which means we
1753   // should not not be holding to any GC alloc regions. The method
1754   // below will make sure of that and do any remaining clean up.
1755   _allocator->abandon_gc_alloc_regions();
1756 
1757   // Instead of tearing down / rebuilding the free lists here, we
1758   // could instead use the remove_all_pending() method on free_list to
1759   // remove only the ones that we need to remove.
1760   tear_down_region_sets(true /* free_list_only */);
1761   shrink_helper(shrink_bytes);
1762   rebuild_region_sets(true /* free_list_only */);
1763 
1764   _hrm.verify_optional();
1765   verify_region_sets_optional();
1766 }
1767 
1768 // Public methods.
1769 
1770 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1771   CollectedHeap(),
1772   _g1_policy(policy_),
1773   _dirty_card_queue_set(false),
1774   _is_alive_closure_cm(this),
1775   _is_alive_closure_stw(this),
1776   _ref_processor_cm(NULL),
1777   _ref_processor_stw(NULL),
1778   _bot_shared(NULL),
1779   _cg1r(NULL),
1780   _g1mm(NULL),
1781   _refine_cte_cl(NULL),
1782   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1783   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1784   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1785   _humongous_reclaim_candidates(),
1786   _has_humongous_reclaim_candidates(false),
1787   _archive_allocator(NULL),
1788   _free_regions_coming(false),
1789   _young_list(new YoungList(this)),
1790   _gc_time_stamp(0),
1791   _summary_bytes_used(0),
1792   _survivor_evac_stats(YoungPLABSize, PLABWeight),
1793   _old_evac_stats(OldPLABSize, PLABWeight),
1794   _expand_heap_after_alloc_failure(true),
1795   _old_marking_cycles_started(0),
1796   _old_marking_cycles_completed(0),
1797   _heap_summary_sent(false),
1798   _in_cset_fast_test(),
1799   _dirty_cards_region_list(NULL),
1800   _worker_cset_start_region(NULL),
1801   _worker_cset_start_region_time_stamp(NULL),
1802   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1803   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1804   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1805   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1806 
1807   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1808                           /* are_GC_task_threads */true,
1809                           /* are_ConcurrentGC_threads */false);
1810   _workers->initialize_workers();
1811 
1812   _allocator = G1Allocator::create_allocator(this);
1813   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1814 
1815   // Override the default _filler_array_max_size so that no humongous filler
1816   // objects are created.
1817   _filler_array_max_size = _humongous_object_threshold_in_words;
1818 
1819   uint n_queues = ParallelGCThreads;
1820   _task_queues = new RefToScanQueueSet(n_queues);
1821 
1822   uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1823   assert(n_rem_sets > 0, "Invariant.");
1824 
1825   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1826   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1827   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1828 
1829   for (uint i = 0; i < n_queues; i++) {
1830     RefToScanQueue* q = new RefToScanQueue();
1831     q->initialize();
1832     _task_queues->register_queue(i, q);
1833     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1834   }
1835   clear_cset_start_regions();
1836 
1837   // Initialize the G1EvacuationFailureALot counters and flags.
1838   NOT_PRODUCT(reset_evacuation_should_fail();)
1839 
1840   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1841 }
1842 
1843 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1844                                                                  size_t size,
1845                                                                  size_t translation_factor) {
1846   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1847   // Allocate a new reserved space, preferring to use large pages.
1848   ReservedSpace rs(size, preferred_page_size);
1849   G1RegionToSpaceMapper* result  =
1850     G1RegionToSpaceMapper::create_mapper(rs,
1851                                          size,
1852                                          rs.alignment(),
1853                                          HeapRegion::GrainBytes,
1854                                          translation_factor,
1855                                          mtGC);
1856   if (TracePageSizes) {
1857     gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1858                            description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1859   }
1860   return result;
1861 }
1862 
1863 jint G1CollectedHeap::initialize() {
1864   CollectedHeap::pre_initialize();
1865   os::enable_vtime();
1866 
1867   G1Log::init();
1868 
1869   // Necessary to satisfy locking discipline assertions.
1870 
1871   MutexLocker x(Heap_lock);
1872 
1873   // We have to initialize the printer before committing the heap, as
1874   // it will be used then.
1875   _hr_printer.set_active(G1PrintHeapRegions);
1876 
1877   // While there are no constraints in the GC code that HeapWordSize
1878   // be any particular value, there are multiple other areas in the
1879   // system which believe this to be true (e.g. oop->object_size in some
1880   // cases incorrectly returns the size in wordSize units rather than
1881   // HeapWordSize).
1882   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1883 
1884   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1885   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1886   size_t heap_alignment = collector_policy()->heap_alignment();
1887 
1888   // Ensure that the sizes are properly aligned.
1889   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1890   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1891   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1892 
1893   _refine_cte_cl = new RefineCardTableEntryClosure();
1894 
1895   jint ecode = JNI_OK;
1896   _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1897   if (_cg1r == NULL) {
1898     return ecode;
1899   }
1900 
1901   // Reserve the maximum.
1902 
1903   // When compressed oops are enabled, the preferred heap base
1904   // is calculated by subtracting the requested size from the
1905   // 32Gb boundary and using the result as the base address for
1906   // heap reservation. If the requested size is not aligned to
1907   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1908   // into the ReservedHeapSpace constructor) then the actual
1909   // base of the reserved heap may end up differing from the
1910   // address that was requested (i.e. the preferred heap base).
1911   // If this happens then we could end up using a non-optimal
1912   // compressed oops mode.
1913 
1914   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1915                                                  heap_alignment);
1916 
1917   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1918 
1919   // Create the barrier set for the entire reserved region.
1920   G1SATBCardTableLoggingModRefBS* bs
1921     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1922   bs->initialize();
1923   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1924   set_barrier_set(bs);
1925 
1926   // Also create a G1 rem set.
1927   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1928 
1929   // Carve out the G1 part of the heap.
1930 
1931   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1932   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1933   G1RegionToSpaceMapper* heap_storage =
1934     G1RegionToSpaceMapper::create_mapper(g1_rs,
1935                                          g1_rs.size(),
1936                                          page_size,
1937                                          HeapRegion::GrainBytes,
1938                                          1,
1939                                          mtJavaHeap);
1940   os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1941                        max_byte_size, page_size,
1942                        heap_rs.base(),
1943                        heap_rs.size());
1944   heap_storage->set_mapping_changed_listener(&_listener);
1945 
1946   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1947   G1RegionToSpaceMapper* bot_storage =
1948     create_aux_memory_mapper("Block offset table",
1949                              G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1950                              G1BlockOffsetSharedArray::heap_map_factor());
1951 
1952   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1953   G1RegionToSpaceMapper* cardtable_storage =
1954     create_aux_memory_mapper("Card table",
1955                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1956                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1957 
1958   G1RegionToSpaceMapper* card_counts_storage =
1959     create_aux_memory_mapper("Card counts table",
1960                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1961                              G1CardCounts::heap_map_factor());
1962 
1963   size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1964   G1RegionToSpaceMapper* prev_bitmap_storage =
1965     create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1966   G1RegionToSpaceMapper* next_bitmap_storage =
1967     create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1968 
1969   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1970   g1_barrier_set()->initialize(cardtable_storage);
1971    // Do later initialization work for concurrent refinement.
1972   _cg1r->init(card_counts_storage);
1973 
1974   // 6843694 - ensure that the maximum region index can fit
1975   // in the remembered set structures.
1976   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1977   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1978 
1979   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1980   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1981   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1982             "too many cards per region");
1983 
1984   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1985 
1986   _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1987 
1988   {
1989     HeapWord* start = _hrm.reserved().start();
1990     HeapWord* end = _hrm.reserved().end();
1991     size_t granularity = HeapRegion::GrainBytes;
1992 
1993     _in_cset_fast_test.initialize(start, end, granularity);
1994     _humongous_reclaim_candidates.initialize(start, end, granularity);
1995   }
1996 
1997   // Create the ConcurrentMark data structure and thread.
1998   // (Must do this late, so that "max_regions" is defined.)
1999   _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2000   if (_cm == NULL || !_cm->completed_initialization()) {
2001     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2002     return JNI_ENOMEM;
2003   }
2004   _cmThread = _cm->cmThread();
2005 
2006   // Initialize the from_card cache structure of HeapRegionRemSet.
2007   HeapRegionRemSet::init_heap(max_regions());
2008 
2009   // Now expand into the initial heap size.
2010   if (!expand(init_byte_size)) {
2011     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2012     return JNI_ENOMEM;
2013   }
2014 
2015   // Perform any initialization actions delegated to the policy.
2016   g1_policy()->init();
2017 
2018   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2019                                                SATB_Q_FL_lock,
2020                                                G1SATBProcessCompletedThreshold,
2021                                                Shared_SATB_Q_lock);
2022 
2023   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2024                                                 DirtyCardQ_CBL_mon,
2025                                                 DirtyCardQ_FL_lock,
2026                                                 concurrent_g1_refine()->yellow_zone(),
2027                                                 concurrent_g1_refine()->red_zone(),
2028                                                 Shared_DirtyCardQ_lock);
2029 
2030   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2031                                     DirtyCardQ_CBL_mon,
2032                                     DirtyCardQ_FL_lock,
2033                                     -1, // never trigger processing
2034                                     -1, // no limit on length
2035                                     Shared_DirtyCardQ_lock,
2036                                     &JavaThread::dirty_card_queue_set());
2037 
2038   // Here we allocate the dummy HeapRegion that is required by the
2039   // G1AllocRegion class.
2040   HeapRegion* dummy_region = _hrm.get_dummy_region();
2041 
2042   // We'll re-use the same region whether the alloc region will
2043   // require BOT updates or not and, if it doesn't, then a non-young
2044   // region will complain that it cannot support allocations without
2045   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2046   dummy_region->set_eden();
2047   // Make sure it's full.
2048   dummy_region->set_top(dummy_region->end());
2049   G1AllocRegion::setup(this, dummy_region);
2050 
2051   _allocator->init_mutator_alloc_region();
2052 
2053   // Do create of the monitoring and management support so that
2054   // values in the heap have been properly initialized.
2055   _g1mm = new G1MonitoringSupport(this);
2056 
2057   G1StringDedup::initialize();
2058 
2059   _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2060   for (uint i = 0; i < ParallelGCThreads; i++) {
2061     new (&_preserved_objs[i]) OopAndMarkOopStack();
2062   }
2063 
2064   return JNI_OK;
2065 }
2066 
2067 void G1CollectedHeap::stop() {
2068   // Stop all concurrent threads. We do this to make sure these threads
2069   // do not continue to execute and access resources (e.g. gclog_or_tty)
2070   // that are destroyed during shutdown.
2071   _cg1r->stop();
2072   _cmThread->stop();
2073   if (G1StringDedup::is_enabled()) {
2074     G1StringDedup::stop();
2075   }
2076 }
2077 
2078 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2079   return HeapRegion::max_region_size();
2080 }
2081 
2082 void G1CollectedHeap::post_initialize() {
2083   CollectedHeap::post_initialize();
2084   ref_processing_init();
2085 }
2086 
2087 void G1CollectedHeap::ref_processing_init() {
2088   // Reference processing in G1 currently works as follows:
2089   //
2090   // * There are two reference processor instances. One is
2091   //   used to record and process discovered references
2092   //   during concurrent marking; the other is used to
2093   //   record and process references during STW pauses
2094   //   (both full and incremental).
2095   // * Both ref processors need to 'span' the entire heap as
2096   //   the regions in the collection set may be dotted around.
2097   //
2098   // * For the concurrent marking ref processor:
2099   //   * Reference discovery is enabled at initial marking.
2100   //   * Reference discovery is disabled and the discovered
2101   //     references processed etc during remarking.
2102   //   * Reference discovery is MT (see below).
2103   //   * Reference discovery requires a barrier (see below).
2104   //   * Reference processing may or may not be MT
2105   //     (depending on the value of ParallelRefProcEnabled
2106   //     and ParallelGCThreads).
2107   //   * A full GC disables reference discovery by the CM
2108   //     ref processor and abandons any entries on it's
2109   //     discovered lists.
2110   //
2111   // * For the STW processor:
2112   //   * Non MT discovery is enabled at the start of a full GC.
2113   //   * Processing and enqueueing during a full GC is non-MT.
2114   //   * During a full GC, references are processed after marking.
2115   //
2116   //   * Discovery (may or may not be MT) is enabled at the start
2117   //     of an incremental evacuation pause.
2118   //   * References are processed near the end of a STW evacuation pause.
2119   //   * For both types of GC:
2120   //     * Discovery is atomic - i.e. not concurrent.
2121   //     * Reference discovery will not need a barrier.
2122 
2123   MemRegion mr = reserved_region();
2124 
2125   // Concurrent Mark ref processor
2126   _ref_processor_cm =
2127     new ReferenceProcessor(mr,    // span
2128                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2129                                 // mt processing
2130                            ParallelGCThreads,
2131                                 // degree of mt processing
2132                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2133                                 // mt discovery
2134                            MAX2(ParallelGCThreads, ConcGCThreads),
2135                                 // degree of mt discovery
2136                            false,
2137                                 // Reference discovery is not atomic
2138                            &_is_alive_closure_cm);
2139                                 // is alive closure
2140                                 // (for efficiency/performance)
2141 
2142   // STW ref processor
2143   _ref_processor_stw =
2144     new ReferenceProcessor(mr,    // span
2145                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2146                                 // mt processing
2147                            ParallelGCThreads,
2148                                 // degree of mt processing
2149                            (ParallelGCThreads > 1),
2150                                 // mt discovery
2151                            ParallelGCThreads,
2152                                 // degree of mt discovery
2153                            true,
2154                                 // Reference discovery is atomic
2155                            &_is_alive_closure_stw);
2156                                 // is alive closure
2157                                 // (for efficiency/performance)
2158 }
2159 
2160 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2161   return g1_policy();
2162 }
2163 
2164 size_t G1CollectedHeap::capacity() const {
2165   return _hrm.length() * HeapRegion::GrainBytes;
2166 }
2167 
2168 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2169   hr->reset_gc_time_stamp();
2170 }
2171 
2172 #ifndef PRODUCT
2173 
2174 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2175 private:
2176   unsigned _gc_time_stamp;
2177   bool _failures;
2178 
2179 public:
2180   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2181     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2182 
2183   virtual bool doHeapRegion(HeapRegion* hr) {
2184     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2185     if (_gc_time_stamp != region_gc_time_stamp) {
2186       gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2187                              "expected %d", HR_FORMAT_PARAMS(hr),
2188                              region_gc_time_stamp, _gc_time_stamp);
2189       _failures = true;
2190     }
2191     return false;
2192   }
2193 
2194   bool failures() { return _failures; }
2195 };
2196 
2197 void G1CollectedHeap::check_gc_time_stamps() {
2198   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2199   heap_region_iterate(&cl);
2200   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2201 }
2202 #endif // PRODUCT
2203 
2204 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2205   _cg1r->hot_card_cache()->drain(cl, worker_i);
2206 }
2207 
2208 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2209   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2210   size_t n_completed_buffers = 0;
2211   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2212     n_completed_buffers++;
2213   }
2214   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2215   dcqs.clear_n_completed_buffers();
2216   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2217 }
2218 
2219 // Computes the sum of the storage used by the various regions.
2220 size_t G1CollectedHeap::used() const {
2221   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2222   if (_archive_allocator != NULL) {
2223     result += _archive_allocator->used();
2224   }
2225   return result;
2226 }
2227 
2228 size_t G1CollectedHeap::used_unlocked() const {
2229   return _summary_bytes_used;
2230 }
2231 
2232 class SumUsedClosure: public HeapRegionClosure {
2233   size_t _used;
2234 public:
2235   SumUsedClosure() : _used(0) {}
2236   bool doHeapRegion(HeapRegion* r) {
2237     _used += r->used();
2238     return false;
2239   }
2240   size_t result() { return _used; }
2241 };
2242 
2243 size_t G1CollectedHeap::recalculate_used() const {
2244   double recalculate_used_start = os::elapsedTime();
2245 
2246   SumUsedClosure blk;
2247   heap_region_iterate(&blk);
2248 
2249   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2250   return blk.result();
2251 }
2252 
2253 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2254   switch (cause) {
2255     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2256     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2257     case GCCause::_dcmd_gc_run:             return ExplicitGCInvokesConcurrent;
2258     case GCCause::_g1_humongous_allocation: return true;
2259     case GCCause::_update_allocation_context_stats_inc: return true;
2260     case GCCause::_wb_conc_mark:            return true;
2261     default:                                return false;
2262   }
2263 }
2264 
2265 #ifndef PRODUCT
2266 void G1CollectedHeap::allocate_dummy_regions() {
2267   // Let's fill up most of the region
2268   size_t word_size = HeapRegion::GrainWords - 1024;
2269   // And as a result the region we'll allocate will be humongous.
2270   guarantee(is_humongous(word_size), "sanity");
2271 
2272   // _filler_array_max_size is set to humongous object threshold
2273   // but temporarily change it to use CollectedHeap::fill_with_object().
2274   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2275 
2276   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2277     // Let's use the existing mechanism for the allocation
2278     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2279                                                  AllocationContext::system());
2280     if (dummy_obj != NULL) {
2281       MemRegion mr(dummy_obj, word_size);
2282       CollectedHeap::fill_with_object(mr);
2283     } else {
2284       // If we can't allocate once, we probably cannot allocate
2285       // again. Let's get out of the loop.
2286       break;
2287     }
2288   }
2289 }
2290 #endif // !PRODUCT
2291 
2292 void G1CollectedHeap::increment_old_marking_cycles_started() {
2293   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2294          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2295          "Wrong marking cycle count (started: %d, completed: %d)",
2296          _old_marking_cycles_started, _old_marking_cycles_completed);
2297 
2298   _old_marking_cycles_started++;
2299 }
2300 
2301 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2302   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2303 
2304   // We assume that if concurrent == true, then the caller is a
2305   // concurrent thread that was joined the Suspendible Thread
2306   // Set. If there's ever a cheap way to check this, we should add an
2307   // assert here.
2308 
2309   // Given that this method is called at the end of a Full GC or of a
2310   // concurrent cycle, and those can be nested (i.e., a Full GC can
2311   // interrupt a concurrent cycle), the number of full collections
2312   // completed should be either one (in the case where there was no
2313   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2314   // behind the number of full collections started.
2315 
2316   // This is the case for the inner caller, i.e. a Full GC.
2317   assert(concurrent ||
2318          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2319          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2320          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2321          "is inconsistent with _old_marking_cycles_completed = %u",
2322          _old_marking_cycles_started, _old_marking_cycles_completed);
2323 
2324   // This is the case for the outer caller, i.e. the concurrent cycle.
2325   assert(!concurrent ||
2326          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2327          "for outer caller (concurrent cycle): "
2328          "_old_marking_cycles_started = %u "
2329          "is inconsistent with _old_marking_cycles_completed = %u",
2330          _old_marking_cycles_started, _old_marking_cycles_completed);
2331 
2332   _old_marking_cycles_completed += 1;
2333 
2334   // We need to clear the "in_progress" flag in the CM thread before
2335   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2336   // is set) so that if a waiter requests another System.gc() it doesn't
2337   // incorrectly see that a marking cycle is still in progress.
2338   if (concurrent) {
2339     _cmThread->set_idle();
2340   }
2341 
2342   // This notify_all() will ensure that a thread that called
2343   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2344   // and it's waiting for a full GC to finish will be woken up. It is
2345   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2346   FullGCCount_lock->notify_all();
2347 }
2348 
2349 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2350   GCIdMarkAndRestore conc_gc_id_mark;
2351   collector_state()->set_concurrent_cycle_started(true);
2352   _gc_timer_cm->register_gc_start(start_time);
2353 
2354   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2355   trace_heap_before_gc(_gc_tracer_cm);
2356   _cmThread->set_gc_id(GCId::current());
2357 }
2358 
2359 void G1CollectedHeap::register_concurrent_cycle_end() {
2360   if (collector_state()->concurrent_cycle_started()) {
2361     GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2362     if (_cm->has_aborted()) {
2363       _gc_tracer_cm->report_concurrent_mode_failure();
2364     }
2365 
2366     _gc_timer_cm->register_gc_end();
2367     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2368 
2369     // Clear state variables to prepare for the next concurrent cycle.
2370      collector_state()->set_concurrent_cycle_started(false);
2371     _heap_summary_sent = false;
2372   }
2373 }
2374 
2375 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2376   if (collector_state()->concurrent_cycle_started()) {
2377     // This function can be called when:
2378     //  the cleanup pause is run
2379     //  the concurrent cycle is aborted before the cleanup pause.
2380     //  the concurrent cycle is aborted after the cleanup pause,
2381     //   but before the concurrent cycle end has been registered.
2382     // Make sure that we only send the heap information once.
2383     if (!_heap_summary_sent) {
2384       GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2385       trace_heap_after_gc(_gc_tracer_cm);
2386       _heap_summary_sent = true;
2387     }
2388   }
2389 }
2390 
2391 void G1CollectedHeap::collect(GCCause::Cause cause) {
2392   assert_heap_not_locked();
2393 
2394   uint gc_count_before;
2395   uint old_marking_count_before;
2396   uint full_gc_count_before;
2397   bool retry_gc;
2398 
2399   do {
2400     retry_gc = false;
2401 
2402     {
2403       MutexLocker ml(Heap_lock);
2404 
2405       // Read the GC count while holding the Heap_lock
2406       gc_count_before = total_collections();
2407       full_gc_count_before = total_full_collections();
2408       old_marking_count_before = _old_marking_cycles_started;
2409     }
2410 
2411     if (should_do_concurrent_full_gc(cause)) {
2412       // Schedule an initial-mark evacuation pause that will start a
2413       // concurrent cycle. We're setting word_size to 0 which means that
2414       // we are not requesting a post-GC allocation.
2415       VM_G1IncCollectionPause op(gc_count_before,
2416                                  0,     /* word_size */
2417                                  true,  /* should_initiate_conc_mark */
2418                                  g1_policy()->max_pause_time_ms(),
2419                                  cause);
2420       op.set_allocation_context(AllocationContext::current());
2421 
2422       VMThread::execute(&op);
2423       if (!op.pause_succeeded()) {
2424         if (old_marking_count_before == _old_marking_cycles_started) {
2425           retry_gc = op.should_retry_gc();
2426         } else {
2427           // A Full GC happened while we were trying to schedule the
2428           // initial-mark GC. No point in starting a new cycle given
2429           // that the whole heap was collected anyway.
2430         }
2431 
2432         if (retry_gc) {
2433           if (GC_locker::is_active_and_needs_gc()) {
2434             GC_locker::stall_until_clear();
2435           }
2436         }
2437       }
2438     } else {
2439       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2440           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2441 
2442         // Schedule a standard evacuation pause. We're setting word_size
2443         // to 0 which means that we are not requesting a post-GC allocation.
2444         VM_G1IncCollectionPause op(gc_count_before,
2445                                    0,     /* word_size */
2446                                    false, /* should_initiate_conc_mark */
2447                                    g1_policy()->max_pause_time_ms(),
2448                                    cause);
2449         VMThread::execute(&op);
2450       } else {
2451         // Schedule a Full GC.
2452         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2453         VMThread::execute(&op);
2454       }
2455     }
2456   } while (retry_gc);
2457 }
2458 
2459 bool G1CollectedHeap::is_in(const void* p) const {
2460   if (_hrm.reserved().contains(p)) {
2461     // Given that we know that p is in the reserved space,
2462     // heap_region_containing() should successfully
2463     // return the containing region.
2464     HeapRegion* hr = heap_region_containing(p);
2465     return hr->is_in(p);
2466   } else {
2467     return false;
2468   }
2469 }
2470 
2471 #ifdef ASSERT
2472 bool G1CollectedHeap::is_in_exact(const void* p) const {
2473   bool contains = reserved_region().contains(p);
2474   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2475   if (contains && available) {
2476     return true;
2477   } else {
2478     return false;
2479   }
2480 }
2481 #endif
2482 
2483 bool G1CollectedHeap::obj_in_cs(oop obj) {
2484   HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2485   return r != NULL && r->in_collection_set();
2486 }
2487 
2488 // Iteration functions.
2489 
2490 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2491 
2492 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2493   ExtendedOopClosure* _cl;
2494 public:
2495   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2496   bool doHeapRegion(HeapRegion* r) {
2497     if (!r->is_continues_humongous()) {
2498       r->oop_iterate(_cl);
2499     }
2500     return false;
2501   }
2502 };
2503 
2504 // Iterates an ObjectClosure over all objects within a HeapRegion.
2505 
2506 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2507   ObjectClosure* _cl;
2508 public:
2509   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2510   bool doHeapRegion(HeapRegion* r) {
2511     if (!r->is_continues_humongous()) {
2512       r->object_iterate(_cl);
2513     }
2514     return false;
2515   }
2516 };
2517 
2518 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2519   IterateObjectClosureRegionClosure blk(cl);
2520   heap_region_iterate(&blk);
2521 }
2522 
2523 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2524   _hrm.iterate(cl);
2525 }
2526 
2527 void
2528 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2529                                          uint worker_id,
2530                                          HeapRegionClaimer *hrclaimer,
2531                                          bool concurrent) const {
2532   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2533 }
2534 
2535 // Clear the cached CSet starting regions and (more importantly)
2536 // the time stamps. Called when we reset the GC time stamp.
2537 void G1CollectedHeap::clear_cset_start_regions() {
2538   assert(_worker_cset_start_region != NULL, "sanity");
2539   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2540 
2541   for (uint i = 0; i < ParallelGCThreads; i++) {
2542     _worker_cset_start_region[i] = NULL;
2543     _worker_cset_start_region_time_stamp[i] = 0;
2544   }
2545 }
2546 
2547 // Given the id of a worker, obtain or calculate a suitable
2548 // starting region for iterating over the current collection set.
2549 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2550   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2551 
2552   HeapRegion* result = NULL;
2553   unsigned gc_time_stamp = get_gc_time_stamp();
2554 
2555   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2556     // Cached starting region for current worker was set
2557     // during the current pause - so it's valid.
2558     // Note: the cached starting heap region may be NULL
2559     // (when the collection set is empty).
2560     result = _worker_cset_start_region[worker_i];
2561     assert(result == NULL || result->in_collection_set(), "sanity");
2562     return result;
2563   }
2564 
2565   // The cached entry was not valid so let's calculate
2566   // a suitable starting heap region for this worker.
2567 
2568   // We want the parallel threads to start their collection
2569   // set iteration at different collection set regions to
2570   // avoid contention.
2571   // If we have:
2572   //          n collection set regions
2573   //          p threads
2574   // Then thread t will start at region floor ((t * n) / p)
2575 
2576   result = g1_policy()->collection_set();
2577   uint cs_size = g1_policy()->cset_region_length();
2578   uint active_workers = workers()->active_workers();
2579 
2580   uint end_ind   = (cs_size * worker_i) / active_workers;
2581   uint start_ind = 0;
2582 
2583   if (worker_i > 0 &&
2584       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2585     // Previous workers starting region is valid
2586     // so let's iterate from there
2587     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2588     result = _worker_cset_start_region[worker_i - 1];
2589   }
2590 
2591   for (uint i = start_ind; i < end_ind; i++) {
2592     result = result->next_in_collection_set();
2593   }
2594 
2595   // Note: the calculated starting heap region may be NULL
2596   // (when the collection set is empty).
2597   assert(result == NULL || result->in_collection_set(), "sanity");
2598   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2599          "should be updated only once per pause");
2600   _worker_cset_start_region[worker_i] = result;
2601   OrderAccess::storestore();
2602   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2603   return result;
2604 }
2605 
2606 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2607   HeapRegion* r = g1_policy()->collection_set();
2608   while (r != NULL) {
2609     HeapRegion* next = r->next_in_collection_set();
2610     if (cl->doHeapRegion(r)) {
2611       cl->incomplete();
2612       return;
2613     }
2614     r = next;
2615   }
2616 }
2617 
2618 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2619                                                   HeapRegionClosure *cl) {
2620   if (r == NULL) {
2621     // The CSet is empty so there's nothing to do.
2622     return;
2623   }
2624 
2625   assert(r->in_collection_set(),
2626          "Start region must be a member of the collection set.");
2627   HeapRegion* cur = r;
2628   while (cur != NULL) {
2629     HeapRegion* next = cur->next_in_collection_set();
2630     if (cl->doHeapRegion(cur) && false) {
2631       cl->incomplete();
2632       return;
2633     }
2634     cur = next;
2635   }
2636   cur = g1_policy()->collection_set();
2637   while (cur != r) {
2638     HeapRegion* next = cur->next_in_collection_set();
2639     if (cl->doHeapRegion(cur) && false) {
2640       cl->incomplete();
2641       return;
2642     }
2643     cur = next;
2644   }
2645 }
2646 
2647 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2648   HeapRegion* result = _hrm.next_region_in_heap(from);
2649   while (result != NULL && result->is_pinned()) {
2650     result = _hrm.next_region_in_heap(result);
2651   }
2652   return result;
2653 }
2654 
2655 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2656   HeapRegion* hr = heap_region_containing(addr);
2657   return hr->block_start(addr);
2658 }
2659 
2660 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2661   HeapRegion* hr = heap_region_containing(addr);
2662   return hr->block_size(addr);
2663 }
2664 
2665 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2666   HeapRegion* hr = heap_region_containing(addr);
2667   return hr->block_is_obj(addr);
2668 }
2669 
2670 bool G1CollectedHeap::supports_tlab_allocation() const {
2671   return true;
2672 }
2673 
2674 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2675   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2676 }
2677 
2678 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2679   return young_list()->eden_used_bytes();
2680 }
2681 
2682 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2683 // must be equal to the humongous object limit.
2684 size_t G1CollectedHeap::max_tlab_size() const {
2685   return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2686 }
2687 
2688 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2689   AllocationContext_t context = AllocationContext::current();
2690   return _allocator->unsafe_max_tlab_alloc(context);
2691 }
2692 
2693 size_t G1CollectedHeap::max_capacity() const {
2694   return _hrm.reserved().byte_size();
2695 }
2696 
2697 jlong G1CollectedHeap::millis_since_last_gc() {
2698   // assert(false, "NYI");
2699   return 0;
2700 }
2701 
2702 void G1CollectedHeap::prepare_for_verify() {
2703   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2704     ensure_parsability(false);
2705   }
2706   g1_rem_set()->prepare_for_verify();
2707 }
2708 
2709 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2710                                               VerifyOption vo) {
2711   switch (vo) {
2712   case VerifyOption_G1UsePrevMarking:
2713     return hr->obj_allocated_since_prev_marking(obj);
2714   case VerifyOption_G1UseNextMarking:
2715     return hr->obj_allocated_since_next_marking(obj);
2716   case VerifyOption_G1UseMarkWord:
2717     return false;
2718   default:
2719     ShouldNotReachHere();
2720   }
2721   return false; // keep some compilers happy
2722 }
2723 
2724 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2725   switch (vo) {
2726   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2727   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2728   case VerifyOption_G1UseMarkWord:    return NULL;
2729   default:                            ShouldNotReachHere();
2730   }
2731   return NULL; // keep some compilers happy
2732 }
2733 
2734 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2735   switch (vo) {
2736   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2737   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2738   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
2739   default:                            ShouldNotReachHere();
2740   }
2741   return false; // keep some compilers happy
2742 }
2743 
2744 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2745   switch (vo) {
2746   case VerifyOption_G1UsePrevMarking: return "PTAMS";
2747   case VerifyOption_G1UseNextMarking: return "NTAMS";
2748   case VerifyOption_G1UseMarkWord:    return "NONE";
2749   default:                            ShouldNotReachHere();
2750   }
2751   return NULL; // keep some compilers happy
2752 }
2753 
2754 class VerifyRootsClosure: public OopClosure {
2755 private:
2756   G1CollectedHeap* _g1h;
2757   VerifyOption     _vo;
2758   bool             _failures;
2759 public:
2760   // _vo == UsePrevMarking -> use "prev" marking information,
2761   // _vo == UseNextMarking -> use "next" marking information,
2762   // _vo == UseMarkWord    -> use mark word from object header.
2763   VerifyRootsClosure(VerifyOption vo) :
2764     _g1h(G1CollectedHeap::heap()),
2765     _vo(vo),
2766     _failures(false) { }
2767 
2768   bool failures() { return _failures; }
2769 
2770   template <class T> void do_oop_nv(T* p) {
2771     T heap_oop = oopDesc::load_heap_oop(p);
2772     if (!oopDesc::is_null(heap_oop)) {
2773       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2774       if (_g1h->is_obj_dead_cond(obj, _vo)) {
2775         gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2776                                "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2777         if (_vo == VerifyOption_G1UseMarkWord) {
2778           gclog_or_tty->print_cr("  Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2779         }
2780         obj->print_on(gclog_or_tty);
2781         _failures = true;
2782       }
2783     }
2784   }
2785 
2786   void do_oop(oop* p)       { do_oop_nv(p); }
2787   void do_oop(narrowOop* p) { do_oop_nv(p); }
2788 };
2789 
2790 class G1VerifyCodeRootOopClosure: public OopClosure {
2791   G1CollectedHeap* _g1h;
2792   OopClosure* _root_cl;
2793   nmethod* _nm;
2794   VerifyOption _vo;
2795   bool _failures;
2796 
2797   template <class T> void do_oop_work(T* p) {
2798     // First verify that this root is live
2799     _root_cl->do_oop(p);
2800 
2801     if (!G1VerifyHeapRegionCodeRoots) {
2802       // We're not verifying the code roots attached to heap region.
2803       return;
2804     }
2805 
2806     // Don't check the code roots during marking verification in a full GC
2807     if (_vo == VerifyOption_G1UseMarkWord) {
2808       return;
2809     }
2810 
2811     // Now verify that the current nmethod (which contains p) is
2812     // in the code root list of the heap region containing the
2813     // object referenced by p.
2814 
2815     T heap_oop = oopDesc::load_heap_oop(p);
2816     if (!oopDesc::is_null(heap_oop)) {
2817       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2818 
2819       // Now fetch the region containing the object
2820       HeapRegion* hr = _g1h->heap_region_containing(obj);
2821       HeapRegionRemSet* hrrs = hr->rem_set();
2822       // Verify that the strong code root list for this region
2823       // contains the nmethod
2824       if (!hrrs->strong_code_roots_list_contains(_nm)) {
2825         gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2826                                "from nmethod " PTR_FORMAT " not in strong "
2827                                "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2828                                p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2829         _failures = true;
2830       }
2831     }
2832   }
2833 
2834 public:
2835   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2836     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2837 
2838   void do_oop(oop* p) { do_oop_work(p); }
2839   void do_oop(narrowOop* p) { do_oop_work(p); }
2840 
2841   void set_nmethod(nmethod* nm) { _nm = nm; }
2842   bool failures() { return _failures; }
2843 };
2844 
2845 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2846   G1VerifyCodeRootOopClosure* _oop_cl;
2847 
2848 public:
2849   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2850     _oop_cl(oop_cl) {}
2851 
2852   void do_code_blob(CodeBlob* cb) {
2853     nmethod* nm = cb->as_nmethod_or_null();
2854     if (nm != NULL) {
2855       _oop_cl->set_nmethod(nm);
2856       nm->oops_do(_oop_cl);
2857     }
2858   }
2859 };
2860 
2861 class YoungRefCounterClosure : public OopClosure {
2862   G1CollectedHeap* _g1h;
2863   int              _count;
2864  public:
2865   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2866   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
2867   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2868 
2869   int count() { return _count; }
2870   void reset_count() { _count = 0; };
2871 };
2872 
2873 class VerifyKlassClosure: public KlassClosure {
2874   YoungRefCounterClosure _young_ref_counter_closure;
2875   OopClosure *_oop_closure;
2876  public:
2877   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2878   void do_klass(Klass* k) {
2879     k->oops_do(_oop_closure);
2880 
2881     _young_ref_counter_closure.reset_count();
2882     k->oops_do(&_young_ref_counter_closure);
2883     if (_young_ref_counter_closure.count() > 0) {
2884       guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2885     }
2886   }
2887 };
2888 
2889 class VerifyLivenessOopClosure: public OopClosure {
2890   G1CollectedHeap* _g1h;
2891   VerifyOption _vo;
2892 public:
2893   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2894     _g1h(g1h), _vo(vo)
2895   { }
2896   void do_oop(narrowOop *p) { do_oop_work(p); }
2897   void do_oop(      oop *p) { do_oop_work(p); }
2898 
2899   template <class T> void do_oop_work(T *p) {
2900     oop obj = oopDesc::load_decode_heap_oop(p);
2901     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2902               "Dead object referenced by a not dead object");
2903   }
2904 };
2905 
2906 class VerifyObjsInRegionClosure: public ObjectClosure {
2907 private:
2908   G1CollectedHeap* _g1h;
2909   size_t _live_bytes;
2910   HeapRegion *_hr;
2911   VerifyOption _vo;
2912 public:
2913   // _vo == UsePrevMarking -> use "prev" marking information,
2914   // _vo == UseNextMarking -> use "next" marking information,
2915   // _vo == UseMarkWord    -> use mark word from object header.
2916   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2917     : _live_bytes(0), _hr(hr), _vo(vo) {
2918     _g1h = G1CollectedHeap::heap();
2919   }
2920   void do_object(oop o) {
2921     VerifyLivenessOopClosure isLive(_g1h, _vo);
2922     assert(o != NULL, "Huh?");
2923     if (!_g1h->is_obj_dead_cond(o, _vo)) {
2924       // If the object is alive according to the mark word,
2925       // then verify that the marking information agrees.
2926       // Note we can't verify the contra-positive of the
2927       // above: if the object is dead (according to the mark
2928       // word), it may not be marked, or may have been marked
2929       // but has since became dead, or may have been allocated
2930       // since the last marking.
2931       if (_vo == VerifyOption_G1UseMarkWord) {
2932         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2933       }
2934 
2935       o->oop_iterate_no_header(&isLive);
2936       if (!_hr->obj_allocated_since_prev_marking(o)) {
2937         size_t obj_size = o->size();    // Make sure we don't overflow
2938         _live_bytes += (obj_size * HeapWordSize);
2939       }
2940     }
2941   }
2942   size_t live_bytes() { return _live_bytes; }
2943 };
2944 
2945 class VerifyArchiveOopClosure: public OopClosure {
2946 public:
2947   VerifyArchiveOopClosure(HeapRegion *hr) { }
2948   void do_oop(narrowOop *p) { do_oop_work(p); }
2949   void do_oop(      oop *p) { do_oop_work(p); }
2950 
2951   template <class T> void do_oop_work(T *p) {
2952     oop obj = oopDesc::load_decode_heap_oop(p);
2953     guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2954               "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2955               p2i(p), p2i(obj));
2956   }
2957 };
2958 
2959 class VerifyArchiveRegionClosure: public ObjectClosure {
2960 public:
2961   VerifyArchiveRegionClosure(HeapRegion *hr) { }
2962   // Verify that all object pointers are to archive regions.
2963   void do_object(oop o) {
2964     VerifyArchiveOopClosure checkOop(NULL);
2965     assert(o != NULL, "Should not be here for NULL oops");
2966     o->oop_iterate_no_header(&checkOop);
2967   }
2968 };
2969 
2970 class VerifyRegionClosure: public HeapRegionClosure {
2971 private:
2972   bool             _par;
2973   VerifyOption     _vo;
2974   bool             _failures;
2975 public:
2976   // _vo == UsePrevMarking -> use "prev" marking information,
2977   // _vo == UseNextMarking -> use "next" marking information,
2978   // _vo == UseMarkWord    -> use mark word from object header.
2979   VerifyRegionClosure(bool par, VerifyOption vo)
2980     : _par(par),
2981       _vo(vo),
2982       _failures(false) {}
2983 
2984   bool failures() {
2985     return _failures;
2986   }
2987 
2988   bool doHeapRegion(HeapRegion* r) {
2989     // For archive regions, verify there are no heap pointers to
2990     // non-pinned regions. For all others, verify liveness info.
2991     if (r->is_archive()) {
2992       VerifyArchiveRegionClosure verify_oop_pointers(r);
2993       r->object_iterate(&verify_oop_pointers);
2994       return true;
2995     }
2996     if (!r->is_continues_humongous()) {
2997       bool failures = false;
2998       r->verify(_vo, &failures);
2999       if (failures) {
3000         _failures = true;
3001       } else if (!r->is_starts_humongous()) {
3002         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3003         r->object_iterate(&not_dead_yet_cl);
3004         if (_vo != VerifyOption_G1UseNextMarking) {
3005           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3006             gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3007                                    "max_live_bytes " SIZE_FORMAT " "
3008                                    "< calculated " SIZE_FORMAT,
3009                                    p2i(r->bottom()), p2i(r->end()),
3010                                    r->max_live_bytes(),
3011                                  not_dead_yet_cl.live_bytes());
3012             _failures = true;
3013           }
3014         } else {
3015           // When vo == UseNextMarking we cannot currently do a sanity
3016           // check on the live bytes as the calculation has not been
3017           // finalized yet.
3018         }
3019       }
3020     }
3021     return false; // stop the region iteration if we hit a failure
3022   }
3023 };
3024 
3025 // This is the task used for parallel verification of the heap regions
3026 
3027 class G1ParVerifyTask: public AbstractGangTask {
3028 private:
3029   G1CollectedHeap*  _g1h;
3030   VerifyOption      _vo;
3031   bool              _failures;
3032   HeapRegionClaimer _hrclaimer;
3033 
3034 public:
3035   // _vo == UsePrevMarking -> use "prev" marking information,
3036   // _vo == UseNextMarking -> use "next" marking information,
3037   // _vo == UseMarkWord    -> use mark word from object header.
3038   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3039       AbstractGangTask("Parallel verify task"),
3040       _g1h(g1h),
3041       _vo(vo),
3042       _failures(false),
3043       _hrclaimer(g1h->workers()->active_workers()) {}
3044 
3045   bool failures() {
3046     return _failures;
3047   }
3048 
3049   void work(uint worker_id) {
3050     HandleMark hm;
3051     VerifyRegionClosure blk(true, _vo);
3052     _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3053     if (blk.failures()) {
3054       _failures = true;
3055     }
3056   }
3057 };
3058 
3059 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3060   if (SafepointSynchronize::is_at_safepoint()) {
3061     assert(Thread::current()->is_VM_thread(),
3062            "Expected to be executed serially by the VM thread at this point");
3063 
3064     if (!silent) { gclog_or_tty->print("Roots "); }
3065     VerifyRootsClosure rootsCl(vo);
3066     VerifyKlassClosure klassCl(this, &rootsCl);
3067     CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3068 
3069     // We apply the relevant closures to all the oops in the
3070     // system dictionary, class loader data graph, the string table
3071     // and the nmethods in the code cache.
3072     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3073     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3074 
3075     {
3076       G1RootProcessor root_processor(this, 1);
3077       root_processor.process_all_roots(&rootsCl,
3078                                        &cldCl,
3079                                        &blobsCl);
3080     }
3081 
3082     bool failures = rootsCl.failures() || codeRootsCl.failures();
3083 
3084     if (vo != VerifyOption_G1UseMarkWord) {
3085       // If we're verifying during a full GC then the region sets
3086       // will have been torn down at the start of the GC. Therefore
3087       // verifying the region sets will fail. So we only verify
3088       // the region sets when not in a full GC.
3089       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3090       verify_region_sets();
3091     }
3092 
3093     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3094     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3095 
3096       G1ParVerifyTask task(this, vo);
3097       workers()->run_task(&task);
3098       if (task.failures()) {
3099         failures = true;
3100       }
3101 
3102     } else {
3103       VerifyRegionClosure blk(false, vo);
3104       heap_region_iterate(&blk);
3105       if (blk.failures()) {
3106         failures = true;
3107       }
3108     }
3109 
3110     if (G1StringDedup::is_enabled()) {
3111       if (!silent) gclog_or_tty->print("StrDedup ");
3112       G1StringDedup::verify();
3113     }
3114 
3115     if (failures) {
3116       gclog_or_tty->print_cr("Heap:");
3117       // It helps to have the per-region information in the output to
3118       // help us track down what went wrong. This is why we call
3119       // print_extended_on() instead of print_on().
3120       print_extended_on(gclog_or_tty);
3121       gclog_or_tty->cr();
3122       gclog_or_tty->flush();
3123     }
3124     guarantee(!failures, "there should not have been any failures");
3125   } else {
3126     if (!silent) {
3127       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3128       if (G1StringDedup::is_enabled()) {
3129         gclog_or_tty->print(", StrDedup");
3130       }
3131       gclog_or_tty->print(") ");
3132     }
3133   }
3134 }
3135 
3136 void G1CollectedHeap::verify(bool silent) {
3137   verify(silent, VerifyOption_G1UsePrevMarking);
3138 }
3139 
3140 double G1CollectedHeap::verify(bool guard, const char* msg) {
3141   double verify_time_ms = 0.0;
3142 
3143   if (guard && total_collections() >= VerifyGCStartAt) {
3144     double verify_start = os::elapsedTime();
3145     HandleMark hm;  // Discard invalid handles created during verification
3146     prepare_for_verify();
3147     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3148     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3149   }
3150 
3151   return verify_time_ms;
3152 }
3153 
3154 void G1CollectedHeap::verify_before_gc() {
3155   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3156   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3157 }
3158 
3159 void G1CollectedHeap::verify_after_gc() {
3160   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3161   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3162 }
3163 
3164 class PrintRegionClosure: public HeapRegionClosure {
3165   outputStream* _st;
3166 public:
3167   PrintRegionClosure(outputStream* st) : _st(st) {}
3168   bool doHeapRegion(HeapRegion* r) {
3169     r->print_on(_st);
3170     return false;
3171   }
3172 };
3173 
3174 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3175                                        const HeapRegion* hr,
3176                                        const VerifyOption vo) const {
3177   switch (vo) {
3178   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3179   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3180   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
3181   default:                            ShouldNotReachHere();
3182   }
3183   return false; // keep some compilers happy
3184 }
3185 
3186 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3187                                        const VerifyOption vo) const {
3188   switch (vo) {
3189   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3190   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3191   case VerifyOption_G1UseMarkWord: {
3192     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3193     return !obj->is_gc_marked() && !hr->is_archive();
3194   }
3195   default:                            ShouldNotReachHere();
3196   }
3197   return false; // keep some compilers happy
3198 }
3199 
3200 void G1CollectedHeap::print_on(outputStream* st) const {
3201   st->print(" %-20s", "garbage-first heap");
3202   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3203             capacity()/K, used_unlocked()/K);
3204   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3205             p2i(_hrm.reserved().start()),
3206             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3207             p2i(_hrm.reserved().end()));
3208   st->cr();
3209   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3210   uint young_regions = _young_list->length();
3211   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3212             (size_t) young_regions * HeapRegion::GrainBytes / K);
3213   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3214   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3215             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3216   st->cr();
3217   MetaspaceAux::print_on(st);
3218 }
3219 
3220 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3221   print_on(st);
3222 
3223   // Print the per-region information.
3224   st->cr();
3225   st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3226                "HS=humongous(starts), HC=humongous(continues), "
3227                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3228                "PTAMS=previous top-at-mark-start, "
3229                "NTAMS=next top-at-mark-start)");
3230   PrintRegionClosure blk(st);
3231   heap_region_iterate(&blk);
3232 }
3233 
3234 void G1CollectedHeap::print_on_error(outputStream* st) const {
3235   this->CollectedHeap::print_on_error(st);
3236 
3237   if (_cm != NULL) {
3238     st->cr();
3239     _cm->print_on_error(st);
3240   }
3241 }
3242 
3243 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3244   workers()->print_worker_threads_on(st);
3245   _cmThread->print_on(st);
3246   st->cr();
3247   _cm->print_worker_threads_on(st);
3248   _cg1r->print_worker_threads_on(st);
3249   if (G1StringDedup::is_enabled()) {
3250     G1StringDedup::print_worker_threads_on(st);
3251   }
3252 }
3253 
3254 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3255   workers()->threads_do(tc);
3256   tc->do_thread(_cmThread);
3257   _cg1r->threads_do(tc);
3258   if (G1StringDedup::is_enabled()) {
3259     G1StringDedup::threads_do(tc);
3260   }
3261 }
3262 
3263 void G1CollectedHeap::print_tracing_info() const {
3264   // We'll overload this to mean "trace GC pause statistics."
3265   if (TraceYoungGenTime || TraceOldGenTime) {
3266     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3267     // to that.
3268     g1_policy()->print_tracing_info();
3269   }
3270   if (G1SummarizeRSetStats) {
3271     g1_rem_set()->print_summary_info();
3272   }
3273   if (G1SummarizeConcMark) {
3274     concurrent_mark()->print_summary_info();
3275   }
3276   g1_policy()->print_yg_surv_rate_info();
3277 }
3278 
3279 #ifndef PRODUCT
3280 // Helpful for debugging RSet issues.
3281 
3282 class PrintRSetsClosure : public HeapRegionClosure {
3283 private:
3284   const char* _msg;
3285   size_t _occupied_sum;
3286 
3287 public:
3288   bool doHeapRegion(HeapRegion* r) {
3289     HeapRegionRemSet* hrrs = r->rem_set();
3290     size_t occupied = hrrs->occupied();
3291     _occupied_sum += occupied;
3292 
3293     gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3294                            HR_FORMAT_PARAMS(r));
3295     if (occupied == 0) {
3296       gclog_or_tty->print_cr("  RSet is empty");
3297     } else {
3298       hrrs->print();
3299     }
3300     gclog_or_tty->print_cr("----------");
3301     return false;
3302   }
3303 
3304   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3305     gclog_or_tty->cr();
3306     gclog_or_tty->print_cr("========================================");
3307     gclog_or_tty->print_cr("%s", msg);
3308     gclog_or_tty->cr();
3309   }
3310 
3311   ~PrintRSetsClosure() {
3312     gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3313     gclog_or_tty->print_cr("========================================");
3314     gclog_or_tty->cr();
3315   }
3316 };
3317 
3318 void G1CollectedHeap::print_cset_rsets() {
3319   PrintRSetsClosure cl("Printing CSet RSets");
3320   collection_set_iterate(&cl);
3321 }
3322 
3323 void G1CollectedHeap::print_all_rsets() {
3324   PrintRSetsClosure cl("Printing All RSets");;
3325   heap_region_iterate(&cl);
3326 }
3327 #endif // PRODUCT
3328 
3329 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3330   YoungList* young_list = heap()->young_list();
3331 
3332   size_t eden_used_bytes = young_list->eden_used_bytes();
3333   size_t survivor_used_bytes = young_list->survivor_used_bytes();
3334 
3335   size_t eden_capacity_bytes =
3336     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3337 
3338   VirtualSpaceSummary heap_summary = create_heap_space_summary();
3339   return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3340 }
3341 
3342 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3343   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3344                        stats->unused(), stats->used(), stats->region_end_waste(),
3345                        stats->regions_filled(), stats->direct_allocated(),
3346                        stats->failure_used(), stats->failure_waste());
3347 }
3348 
3349 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3350   const G1HeapSummary& heap_summary = create_g1_heap_summary();
3351   gc_tracer->report_gc_heap_summary(when, heap_summary);
3352 
3353   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3354   gc_tracer->report_metaspace_summary(when, metaspace_summary);
3355 }
3356 
3357 
3358 G1CollectedHeap* G1CollectedHeap::heap() {
3359   CollectedHeap* heap = Universe::heap();
3360   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3361   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3362   return (G1CollectedHeap*)heap;
3363 }
3364 
3365 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3366   // always_do_update_barrier = false;
3367   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3368   // Fill TLAB's and such
3369   accumulate_statistics_all_tlabs();
3370   ensure_parsability(true);
3371 
3372   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3373       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3374     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3375   }
3376 }
3377 
3378 void G1CollectedHeap::gc_epilogue(bool full) {
3379 
3380   if (G1SummarizeRSetStats &&
3381       (G1SummarizeRSetStatsPeriod > 0) &&
3382       // we are at the end of the GC. Total collections has already been increased.
3383       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3384     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3385   }
3386 
3387   // FIXME: what is this about?
3388   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3389   // is set.
3390 #if defined(COMPILER2) || INCLUDE_JVMCI
3391   assert(DerivedPointerTable::is_empty(), "derived pointer present");
3392 #endif
3393   // always_do_update_barrier = true;
3394 
3395   resize_all_tlabs();
3396   allocation_context_stats().update(full);
3397 
3398   // We have just completed a GC. Update the soft reference
3399   // policy with the new heap occupancy
3400   Universe::update_heap_info_at_gc();
3401 }
3402 
3403 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3404                                                uint gc_count_before,
3405                                                bool* succeeded,
3406                                                GCCause::Cause gc_cause) {
3407   assert_heap_not_locked_and_not_at_safepoint();
3408   g1_policy()->record_stop_world_start();
3409   VM_G1IncCollectionPause op(gc_count_before,
3410                              word_size,
3411                              false, /* should_initiate_conc_mark */
3412                              g1_policy()->max_pause_time_ms(),
3413                              gc_cause);
3414 
3415   op.set_allocation_context(AllocationContext::current());
3416   VMThread::execute(&op);
3417 
3418   HeapWord* result = op.result();
3419   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3420   assert(result == NULL || ret_succeeded,
3421          "the result should be NULL if the VM did not succeed");
3422   *succeeded = ret_succeeded;
3423 
3424   assert_heap_not_locked();
3425   return result;
3426 }
3427 
3428 void
3429 G1CollectedHeap::doConcurrentMark() {
3430   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3431   if (!_cmThread->in_progress()) {
3432     _cmThread->set_started();
3433     CGC_lock->notify();
3434   }
3435 }
3436 
3437 size_t G1CollectedHeap::pending_card_num() {
3438   size_t extra_cards = 0;
3439   JavaThread *curr = Threads::first();
3440   while (curr != NULL) {
3441     DirtyCardQueue& dcq = curr->dirty_card_queue();
3442     extra_cards += dcq.size();
3443     curr = curr->next();
3444   }
3445   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3446   size_t buffer_size = dcqs.buffer_size();
3447   size_t buffer_num = dcqs.completed_buffers_num();
3448 
3449   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3450   // in bytes - not the number of 'entries'. We need to convert
3451   // into a number of cards.
3452   return (buffer_size * buffer_num + extra_cards) / oopSize;
3453 }
3454 
3455 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3456  private:
3457   size_t _total_humongous;
3458   size_t _candidate_humongous;
3459 
3460   DirtyCardQueue _dcq;
3461 
3462   // We don't nominate objects with many remembered set entries, on
3463   // the assumption that such objects are likely still live.
3464   bool is_remset_small(HeapRegion* region) const {
3465     HeapRegionRemSet* const rset = region->rem_set();
3466     return G1EagerReclaimHumongousObjectsWithStaleRefs
3467       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3468       : rset->is_empty();
3469   }
3470 
3471   bool is_typeArray_region(HeapRegion* region) const {
3472     return oop(region->bottom())->is_typeArray();
3473   }
3474 
3475   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3476     assert(region->is_starts_humongous(), "Must start a humongous object");
3477 
3478     // Candidate selection must satisfy the following constraints
3479     // while concurrent marking is in progress:
3480     //
3481     // * In order to maintain SATB invariants, an object must not be
3482     // reclaimed if it was allocated before the start of marking and
3483     // has not had its references scanned.  Such an object must have
3484     // its references (including type metadata) scanned to ensure no
3485     // live objects are missed by the marking process.  Objects
3486     // allocated after the start of concurrent marking don't need to
3487     // be scanned.
3488     //
3489     // * An object must not be reclaimed if it is on the concurrent
3490     // mark stack.  Objects allocated after the start of concurrent
3491     // marking are never pushed on the mark stack.
3492     //
3493     // Nominating only objects allocated after the start of concurrent
3494     // marking is sufficient to meet both constraints.  This may miss
3495     // some objects that satisfy the constraints, but the marking data
3496     // structures don't support efficiently performing the needed
3497     // additional tests or scrubbing of the mark stack.
3498     //
3499     // However, we presently only nominate is_typeArray() objects.
3500     // A humongous object containing references induces remembered
3501     // set entries on other regions.  In order to reclaim such an
3502     // object, those remembered sets would need to be cleaned up.
3503     //
3504     // We also treat is_typeArray() objects specially, allowing them
3505     // to be reclaimed even if allocated before the start of
3506     // concurrent mark.  For this we rely on mark stack insertion to
3507     // exclude is_typeArray() objects, preventing reclaiming an object
3508     // that is in the mark stack.  We also rely on the metadata for
3509     // such objects to be built-in and so ensured to be kept live.
3510     // Frequent allocation and drop of large binary blobs is an
3511     // important use case for eager reclaim, and this special handling
3512     // may reduce needed headroom.
3513 
3514     return is_typeArray_region(region) && is_remset_small(region);
3515   }
3516 
3517  public:
3518   RegisterHumongousWithInCSetFastTestClosure()
3519   : _total_humongous(0),
3520     _candidate_humongous(0),
3521     _dcq(&JavaThread::dirty_card_queue_set()) {
3522   }
3523 
3524   virtual bool doHeapRegion(HeapRegion* r) {
3525     if (!r->is_starts_humongous()) {
3526       return false;
3527     }
3528     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3529 
3530     bool is_candidate = humongous_region_is_candidate(g1h, r);
3531     uint rindex = r->hrm_index();
3532     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3533     if (is_candidate) {
3534       _candidate_humongous++;
3535       g1h->register_humongous_region_with_cset(rindex);
3536       // Is_candidate already filters out humongous object with large remembered sets.
3537       // If we have a humongous object with a few remembered sets, we simply flush these
3538       // remembered set entries into the DCQS. That will result in automatic
3539       // re-evaluation of their remembered set entries during the following evacuation
3540       // phase.
3541       if (!r->rem_set()->is_empty()) {
3542         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3543                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3544         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3545         HeapRegionRemSetIterator hrrs(r->rem_set());
3546         size_t card_index;
3547         while (hrrs.has_next(card_index)) {
3548           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3549           // The remembered set might contain references to already freed
3550           // regions. Filter out such entries to avoid failing card table
3551           // verification.
3552           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3553             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3554               *card_ptr = CardTableModRefBS::dirty_card_val();
3555               _dcq.enqueue(card_ptr);
3556             }
3557           }
3558         }
3559         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3560                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3561                hrrs.n_yielded(), r->rem_set()->occupied());
3562         r->rem_set()->clear_locked();
3563       }
3564       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3565     }
3566     _total_humongous++;
3567 
3568     return false;
3569   }
3570 
3571   size_t total_humongous() const { return _total_humongous; }
3572   size_t candidate_humongous() const { return _candidate_humongous; }
3573 
3574   void flush_rem_set_entries() { _dcq.flush(); }
3575 };
3576 
3577 void G1CollectedHeap::register_humongous_regions_with_cset() {
3578   if (!G1EagerReclaimHumongousObjects) {
3579     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3580     return;
3581   }
3582   double time = os::elapsed_counter();
3583 
3584   // Collect reclaim candidate information and register candidates with cset.
3585   RegisterHumongousWithInCSetFastTestClosure cl;
3586   heap_region_iterate(&cl);
3587 
3588   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3589   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3590                                                                   cl.total_humongous(),
3591                                                                   cl.candidate_humongous());
3592   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3593 
3594   // Finally flush all remembered set entries to re-check into the global DCQS.
3595   cl.flush_rem_set_entries();
3596 }
3597 
3598 #ifdef ASSERT
3599 class VerifyCSetClosure: public HeapRegionClosure {
3600 public:
3601   bool doHeapRegion(HeapRegion* hr) {
3602     // Here we check that the CSet region's RSet is ready for parallel
3603     // iteration. The fields that we'll verify are only manipulated
3604     // when the region is part of a CSet and is collected. Afterwards,
3605     // we reset these fields when we clear the region's RSet (when the
3606     // region is freed) so they are ready when the region is
3607     // re-allocated. The only exception to this is if there's an
3608     // evacuation failure and instead of freeing the region we leave
3609     // it in the heap. In that case, we reset these fields during
3610     // evacuation failure handling.
3611     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3612 
3613     // Here's a good place to add any other checks we'd like to
3614     // perform on CSet regions.
3615     return false;
3616   }
3617 };
3618 #endif // ASSERT
3619 
3620 uint G1CollectedHeap::num_task_queues() const {
3621   return _task_queues->size();
3622 }
3623 
3624 #if TASKQUEUE_STATS
3625 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3626   st->print_raw_cr("GC Task Stats");
3627   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3628   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3629 }
3630 
3631 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3632   print_taskqueue_stats_hdr(st);
3633 
3634   TaskQueueStats totals;
3635   const uint n = num_task_queues();
3636   for (uint i = 0; i < n; ++i) {
3637     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3638     totals += task_queue(i)->stats;
3639   }
3640   st->print_raw("tot "); totals.print(st); st->cr();
3641 
3642   DEBUG_ONLY(totals.verify());
3643 }
3644 
3645 void G1CollectedHeap::reset_taskqueue_stats() {
3646   const uint n = num_task_queues();
3647   for (uint i = 0; i < n; ++i) {
3648     task_queue(i)->stats.reset();
3649   }
3650 }
3651 #endif // TASKQUEUE_STATS
3652 
3653 void G1CollectedHeap::log_gc_header() {
3654   if (!G1Log::fine()) {
3655     return;
3656   }
3657 
3658   gclog_or_tty->gclog_stamp();
3659 
3660   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3661     .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3662     .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3663 
3664   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3665 }
3666 
3667 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3668   if (!G1Log::fine()) {
3669     return;
3670   }
3671 
3672   if (G1Log::finer()) {
3673     if (evacuation_failed()) {
3674       gclog_or_tty->print(" (to-space exhausted)");
3675     }
3676     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3677     g1_policy()->print_phases(pause_time_sec);
3678     g1_policy()->print_detailed_heap_transition();
3679   } else {
3680     if (evacuation_failed()) {
3681       gclog_or_tty->print("--");
3682     }
3683     g1_policy()->print_heap_transition();
3684     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3685   }
3686   gclog_or_tty->flush();
3687 }
3688 
3689 void G1CollectedHeap::wait_for_root_region_scanning() {
3690   double scan_wait_start = os::elapsedTime();
3691   // We have to wait until the CM threads finish scanning the
3692   // root regions as it's the only way to ensure that all the
3693   // objects on them have been correctly scanned before we start
3694   // moving them during the GC.
3695   bool waited = _cm->root_regions()->wait_until_scan_finished();
3696   double wait_time_ms = 0.0;
3697   if (waited) {
3698     double scan_wait_end = os::elapsedTime();
3699     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3700   }
3701   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3702 }
3703 
3704 bool
3705 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3706   assert_at_safepoint(true /* should_be_vm_thread */);
3707   guarantee(!is_gc_active(), "collection is not reentrant");
3708 
3709   if (GC_locker::check_active_before_gc()) {
3710     return false;
3711   }
3712 
3713   _gc_timer_stw->register_gc_start();
3714 
3715   GCIdMark gc_id_mark;
3716   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3717 
3718   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3719   ResourceMark rm;
3720 
3721   wait_for_root_region_scanning();
3722 
3723   G1Log::update_level();
3724   print_heap_before_gc();
3725   trace_heap_before_gc(_gc_tracer_stw);
3726 
3727   verify_region_sets_optional();
3728   verify_dirty_young_regions();
3729 
3730   // This call will decide whether this pause is an initial-mark
3731   // pause. If it is, during_initial_mark_pause() will return true
3732   // for the duration of this pause.
3733   g1_policy()->decide_on_conc_mark_initiation();
3734 
3735   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3736   assert(!collector_state()->during_initial_mark_pause() ||
3737           collector_state()->gcs_are_young(), "sanity");
3738 
3739   // We also do not allow mixed GCs during marking.
3740   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3741 
3742   // Record whether this pause is an initial mark. When the current
3743   // thread has completed its logging output and it's safe to signal
3744   // the CM thread, the flag's value in the policy has been reset.
3745   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3746 
3747   // Inner scope for scope based logging, timers, and stats collection
3748   {
3749     EvacuationInfo evacuation_info;
3750 
3751     if (collector_state()->during_initial_mark_pause()) {
3752       // We are about to start a marking cycle, so we increment the
3753       // full collection counter.
3754       increment_old_marking_cycles_started();
3755       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3756     }
3757 
3758     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3759 
3760     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3761 
3762     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3763                                                                   workers()->active_workers(),
3764                                                                   Threads::number_of_non_daemon_threads());
3765     workers()->set_active_workers(active_workers);
3766 
3767     double pause_start_sec = os::elapsedTime();
3768     g1_policy()->note_gc_start(active_workers);
3769     log_gc_header();
3770 
3771     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3772     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3773 
3774     // If the secondary_free_list is not empty, append it to the
3775     // free_list. No need to wait for the cleanup operation to finish;
3776     // the region allocation code will check the secondary_free_list
3777     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3778     // set, skip this step so that the region allocation code has to
3779     // get entries from the secondary_free_list.
3780     if (!G1StressConcRegionFreeing) {
3781       append_secondary_free_list_if_not_empty_with_lock();
3782     }
3783 
3784     assert(check_young_list_well_formed(), "young list should be well formed");
3785 
3786     // Don't dynamically change the number of GC threads this early.  A value of
3787     // 0 is used to indicate serial work.  When parallel work is done,
3788     // it will be set.
3789 
3790     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3791       IsGCActiveMark x;
3792 
3793       gc_prologue(false);
3794       increment_total_collections(false /* full gc */);
3795       increment_gc_time_stamp();
3796 
3797       verify_before_gc();
3798 
3799       check_bitmaps("GC Start");
3800 
3801 #if defined(COMPILER2) || INCLUDE_JVMCI
3802       DerivedPointerTable::clear();
3803 #endif
3804 
3805       // Please see comment in g1CollectedHeap.hpp and
3806       // G1CollectedHeap::ref_processing_init() to see how
3807       // reference processing currently works in G1.
3808 
3809       // Enable discovery in the STW reference processor
3810       ref_processor_stw()->enable_discovery();
3811 
3812       {
3813         // We want to temporarily turn off discovery by the
3814         // CM ref processor, if necessary, and turn it back on
3815         // on again later if we do. Using a scoped
3816         // NoRefDiscovery object will do this.
3817         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3818 
3819         // Forget the current alloc region (we might even choose it to be part
3820         // of the collection set!).
3821         _allocator->release_mutator_alloc_region();
3822 
3823         // We should call this after we retire the mutator alloc
3824         // region(s) so that all the ALLOC / RETIRE events are generated
3825         // before the start GC event.
3826         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3827 
3828         // This timing is only used by the ergonomics to handle our pause target.
3829         // It is unclear why this should not include the full pause. We will
3830         // investigate this in CR 7178365.
3831         //
3832         // Preserving the old comment here if that helps the investigation:
3833         //
3834         // The elapsed time induced by the start time below deliberately elides
3835         // the possible verification above.
3836         double sample_start_time_sec = os::elapsedTime();
3837 
3838         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3839 
3840         if (collector_state()->during_initial_mark_pause()) {
3841           concurrent_mark()->checkpointRootsInitialPre();
3842         }
3843 
3844         double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3845         g1_policy()->finalize_old_cset_part(time_remaining_ms);
3846 
3847         evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3848 
3849         // Make sure the remembered sets are up to date. This needs to be
3850         // done before register_humongous_regions_with_cset(), because the
3851         // remembered sets are used there to choose eager reclaim candidates.
3852         // If the remembered sets are not up to date we might miss some
3853         // entries that need to be handled.
3854         g1_rem_set()->cleanupHRRS();
3855 
3856         register_humongous_regions_with_cset();
3857 
3858         assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3859 
3860         _cm->note_start_of_gc();
3861         // We call this after finalize_cset() to
3862         // ensure that the CSet has been finalized.
3863         _cm->verify_no_cset_oops();
3864 
3865         if (_hr_printer.is_active()) {
3866           HeapRegion* hr = g1_policy()->collection_set();
3867           while (hr != NULL) {
3868             _hr_printer.cset(hr);
3869             hr = hr->next_in_collection_set();
3870           }
3871         }
3872 
3873 #ifdef ASSERT
3874         VerifyCSetClosure cl;
3875         collection_set_iterate(&cl);
3876 #endif // ASSERT
3877 
3878         // Initialize the GC alloc regions.
3879         _allocator->init_gc_alloc_regions(evacuation_info);
3880 
3881         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3882         pre_evacuate_collection_set();
3883 
3884         // Actually do the work...
3885         evacuate_collection_set(evacuation_info, &per_thread_states);
3886 
3887         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3888 
3889         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3890         free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3891 
3892         eagerly_reclaim_humongous_regions();
3893 
3894         g1_policy()->clear_collection_set();
3895 
3896         // Start a new incremental collection set for the next pause.
3897         g1_policy()->start_incremental_cset_building();
3898 
3899         clear_cset_fast_test();
3900 
3901         _young_list->reset_sampled_info();
3902 
3903         // Don't check the whole heap at this point as the
3904         // GC alloc regions from this pause have been tagged
3905         // as survivors and moved on to the survivor list.
3906         // Survivor regions will fail the !is_young() check.
3907         assert(check_young_list_empty(false /* check_heap */),
3908           "young list should be empty");
3909 
3910         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3911                                              _young_list->first_survivor_region(),
3912                                              _young_list->last_survivor_region());
3913 
3914         _young_list->reset_auxilary_lists();
3915 
3916         if (evacuation_failed()) {
3917           set_used(recalculate_used());
3918           if (_archive_allocator != NULL) {
3919             _archive_allocator->clear_used();
3920           }
3921           for (uint i = 0; i < ParallelGCThreads; i++) {
3922             if (_evacuation_failed_info_array[i].has_failed()) {
3923               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3924             }
3925           }
3926         } else {
3927           // The "used" of the the collection set have already been subtracted
3928           // when they were freed.  Add in the bytes evacuated.
3929           increase_used(g1_policy()->bytes_copied_during_gc());
3930         }
3931 
3932         if (collector_state()->during_initial_mark_pause()) {
3933           // We have to do this before we notify the CM threads that
3934           // they can start working to make sure that all the
3935           // appropriate initialization is done on the CM object.
3936           concurrent_mark()->checkpointRootsInitialPost();
3937           collector_state()->set_mark_in_progress(true);
3938           // Note that we don't actually trigger the CM thread at
3939           // this point. We do that later when we're sure that
3940           // the current thread has completed its logging output.
3941         }
3942 
3943         allocate_dummy_regions();
3944 
3945         _allocator->init_mutator_alloc_region();
3946 
3947         {
3948           size_t expand_bytes = g1_policy()->expansion_amount();
3949           if (expand_bytes > 0) {
3950             size_t bytes_before = capacity();
3951             // No need for an ergo verbose message here,
3952             // expansion_amount() does this when it returns a value > 0.
3953             double expand_ms;
3954             if (!expand(expand_bytes, &expand_ms)) {
3955               // We failed to expand the heap. Cannot do anything about it.
3956             }
3957             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3958           }
3959         }
3960 
3961         // We redo the verification but now wrt to the new CSet which
3962         // has just got initialized after the previous CSet was freed.
3963         _cm->verify_no_cset_oops();
3964         _cm->note_end_of_gc();
3965 
3966         // This timing is only used by the ergonomics to handle our pause target.
3967         // It is unclear why this should not include the full pause. We will
3968         // investigate this in CR 7178365.
3969         double sample_end_time_sec = os::elapsedTime();
3970         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3971         size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3972         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3973 
3974         evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3975         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3976 
3977         MemoryService::track_memory_usage();
3978 
3979         // In prepare_for_verify() below we'll need to scan the deferred
3980         // update buffers to bring the RSets up-to-date if
3981         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3982         // the update buffers we'll probably need to scan cards on the
3983         // regions we just allocated to (i.e., the GC alloc
3984         // regions). However, during the last GC we called
3985         // set_saved_mark() on all the GC alloc regions, so card
3986         // scanning might skip the [saved_mark_word()...top()] area of
3987         // those regions (i.e., the area we allocated objects into
3988         // during the last GC). But it shouldn't. Given that
3989         // saved_mark_word() is conditional on whether the GC time stamp
3990         // on the region is current or not, by incrementing the GC time
3991         // stamp here we invalidate all the GC time stamps on all the
3992         // regions and saved_mark_word() will simply return top() for
3993         // all the regions. This is a nicer way of ensuring this rather
3994         // than iterating over the regions and fixing them. In fact, the
3995         // GC time stamp increment here also ensures that
3996         // saved_mark_word() will return top() between pauses, i.e.,
3997         // during concurrent refinement. So we don't need the
3998         // is_gc_active() check to decided which top to use when
3999         // scanning cards (see CR 7039627).
4000         increment_gc_time_stamp();
4001 
4002         verify_after_gc();
4003         check_bitmaps("GC End");
4004 
4005         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4006         ref_processor_stw()->verify_no_references_recorded();
4007 
4008         // CM reference discovery will be re-enabled if necessary.
4009       }
4010 
4011       // We should do this after we potentially expand the heap so
4012       // that all the COMMIT events are generated before the end GC
4013       // event, and after we retire the GC alloc regions so that all
4014       // RETIRE events are generated before the end GC event.
4015       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4016 
4017 #ifdef TRACESPINNING
4018       ParallelTaskTerminator::print_termination_counts();
4019 #endif
4020 
4021       gc_epilogue(false);
4022     }
4023 
4024     // Print the remainder of the GC log output.
4025     log_gc_footer(os::elapsedTime() - pause_start_sec);
4026 
4027     // It is not yet to safe to tell the concurrent mark to
4028     // start as we have some optional output below. We don't want the
4029     // output from the concurrent mark thread interfering with this
4030     // logging output either.
4031 
4032     _hrm.verify_optional();
4033     verify_region_sets_optional();
4034 
4035     TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4036     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4037 
4038     print_heap_after_gc();
4039     trace_heap_after_gc(_gc_tracer_stw);
4040 
4041     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4042     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4043     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4044     // before any GC notifications are raised.
4045     g1mm()->update_sizes();
4046 
4047     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4048     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4049     _gc_timer_stw->register_gc_end();
4050     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4051   }
4052   // It should now be safe to tell the concurrent mark thread to start
4053   // without its logging output interfering with the logging output
4054   // that came from the pause.
4055 
4056   if (should_start_conc_mark) {
4057     // CAUTION: after the doConcurrentMark() call below,
4058     // the concurrent marking thread(s) could be running
4059     // concurrently with us. Make sure that anything after
4060     // this point does not assume that we are the only GC thread
4061     // running. Note: of course, the actual marking work will
4062     // not start until the safepoint itself is released in
4063     // SuspendibleThreadSet::desynchronize().
4064     doConcurrentMark();
4065   }
4066 
4067   return true;
4068 }
4069 
4070 void G1CollectedHeap::remove_self_forwarding_pointers() {
4071   double remove_self_forwards_start = os::elapsedTime();
4072 
4073   G1ParRemoveSelfForwardPtrsTask rsfp_task;
4074   workers()->run_task(&rsfp_task);
4075 
4076   // Now restore saved marks, if any.
4077   for (uint i = 0; i < ParallelGCThreads; i++) {
4078     OopAndMarkOopStack& cur = _preserved_objs[i];
4079     while (!cur.is_empty()) {
4080       OopAndMarkOop elem = cur.pop();
4081       elem.set_mark();
4082     }
4083     cur.clear(true);
4084   }
4085 
4086   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4087 }
4088 
4089 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4090   if (!_evacuation_failed) {
4091     _evacuation_failed = true;
4092   }
4093 
4094   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4095 
4096   // We want to call the "for_promotion_failure" version only in the
4097   // case of a promotion failure.
4098   if (m->must_be_preserved_for_promotion_failure(obj)) {
4099     OopAndMarkOop elem(obj, m);
4100     _preserved_objs[worker_id].push(elem);
4101   }
4102 }
4103 
4104 class G1ParEvacuateFollowersClosure : public VoidClosure {
4105 private:
4106   double _start_term;
4107   double _term_time;
4108   size_t _term_attempts;
4109 
4110   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4111   void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4112 protected:
4113   G1CollectedHeap*              _g1h;
4114   G1ParScanThreadState*         _par_scan_state;
4115   RefToScanQueueSet*            _queues;
4116   ParallelTaskTerminator*       _terminator;
4117 
4118   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4119   RefToScanQueueSet*      queues()         { return _queues; }
4120   ParallelTaskTerminator* terminator()     { return _terminator; }
4121 
4122 public:
4123   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4124                                 G1ParScanThreadState* par_scan_state,
4125                                 RefToScanQueueSet* queues,
4126                                 ParallelTaskTerminator* terminator)
4127     : _g1h(g1h), _par_scan_state(par_scan_state),
4128       _queues(queues), _terminator(terminator),
4129       _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4130 
4131   void do_void();
4132 
4133   double term_time() const { return _term_time; }
4134   size_t term_attempts() const { return _term_attempts; }
4135 
4136 private:
4137   inline bool offer_termination();
4138 };
4139 
4140 bool G1ParEvacuateFollowersClosure::offer_termination() {
4141   G1ParScanThreadState* const pss = par_scan_state();
4142   start_term_time();
4143   const bool res = terminator()->offer_termination();
4144   end_term_time();
4145   return res;
4146 }
4147 
4148 void G1ParEvacuateFollowersClosure::do_void() {
4149   G1ParScanThreadState* const pss = par_scan_state();
4150   pss->trim_queue();
4151   do {
4152     pss->steal_and_trim_queue(queues());
4153   } while (!offer_termination());
4154 }
4155 
4156 class G1ParTask : public AbstractGangTask {
4157 protected:
4158   G1CollectedHeap*         _g1h;
4159   G1ParScanThreadStateSet* _pss;
4160   RefToScanQueueSet*       _queues;
4161   G1RootProcessor*         _root_processor;
4162   ParallelTaskTerminator   _terminator;
4163   uint                     _n_workers;
4164 
4165 public:
4166   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4167     : AbstractGangTask("G1 collection"),
4168       _g1h(g1h),
4169       _pss(per_thread_states),
4170       _queues(task_queues),
4171       _root_processor(root_processor),
4172       _terminator(n_workers, _queues),
4173       _n_workers(n_workers)
4174   {}
4175 
4176   void work(uint worker_id) {
4177     if (worker_id >= _n_workers) return;  // no work needed this round
4178 
4179     double start_sec = os::elapsedTime();
4180     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4181 
4182     {
4183       ResourceMark rm;
4184       HandleMark   hm;
4185 
4186       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4187 
4188       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
4189       pss->set_ref_processor(rp);
4190 
4191       double start_strong_roots_sec = os::elapsedTime();
4192 
4193       _root_processor->evacuate_roots(pss->closures(), worker_id);
4194 
4195       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4196 
4197       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4198       // treating the nmethods visited to act as roots for concurrent marking.
4199       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4200       // objects copied by the current evacuation.
4201       size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4202                                                                              pss->closures()->weak_codeblobs(),
4203                                                                              worker_id);
4204 
4205       _pss->add_cards_scanned(worker_id, cards_scanned);
4206 
4207       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4208 
4209       double term_sec = 0.0;
4210       size_t evac_term_attempts = 0;
4211       {
4212         double start = os::elapsedTime();
4213         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4214         evac.do_void();
4215 
4216         evac_term_attempts = evac.term_attempts();
4217         term_sec = evac.term_time();
4218         double elapsed_sec = os::elapsedTime() - start;
4219         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4220         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4221         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4222       }
4223 
4224       assert(pss->queue_is_empty(), "should be empty");
4225 
4226       if (PrintTerminationStats) {
4227         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4228         size_t lab_waste;
4229         size_t lab_undo_waste;
4230         pss->waste(lab_waste, lab_undo_waste);
4231         _g1h->print_termination_stats(gclog_or_tty,
4232                                       worker_id,
4233                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
4234                                       strong_roots_sec * 1000.0,                  /* strong roots time */
4235                                       term_sec * 1000.0,                          /* evac term time */
4236                                       evac_term_attempts,                         /* evac term attempts */
4237                                       lab_waste,                                  /* alloc buffer waste */
4238                                       lab_undo_waste                              /* undo waste */
4239                                       );
4240       }
4241 
4242       // Close the inner scope so that the ResourceMark and HandleMark
4243       // destructors are executed here and are included as part of the
4244       // "GC Worker Time".
4245     }
4246     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4247   }
4248 };
4249 
4250 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4251   st->print_raw_cr("GC Termination Stats");
4252   st->print_raw_cr("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
4253   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts  total   alloc    undo");
4254   st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4255 }
4256 
4257 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4258                                               uint worker_id,
4259                                               double elapsed_ms,
4260                                               double strong_roots_ms,
4261                                               double term_ms,
4262                                               size_t term_attempts,
4263                                               size_t alloc_buffer_waste,
4264                                               size_t undo_waste) const {
4265   st->print_cr("%3d %9.2f %9.2f %6.2f "
4266                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4267                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4268                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4269                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4270                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4271                alloc_buffer_waste * HeapWordSize / K,
4272                undo_waste * HeapWordSize / K);
4273 }
4274 
4275 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4276 private:
4277   BoolObjectClosure* _is_alive;
4278   int _initial_string_table_size;
4279   int _initial_symbol_table_size;
4280 
4281   bool  _process_strings;
4282   int _strings_processed;
4283   int _strings_removed;
4284 
4285   bool  _process_symbols;
4286   int _symbols_processed;
4287   int _symbols_removed;
4288 
4289 public:
4290   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4291     AbstractGangTask("String/Symbol Unlinking"),
4292     _is_alive(is_alive),
4293     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4294     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4295 
4296     _initial_string_table_size = StringTable::the_table()->table_size();
4297     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4298     if (process_strings) {
4299       StringTable::clear_parallel_claimed_index();
4300     }
4301     if (process_symbols) {
4302       SymbolTable::clear_parallel_claimed_index();
4303     }
4304   }
4305 
4306   ~G1StringSymbolTableUnlinkTask() {
4307     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4308               "claim value %d after unlink less than initial string table size %d",
4309               StringTable::parallel_claimed_index(), _initial_string_table_size);
4310     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4311               "claim value %d after unlink less than initial symbol table size %d",
4312               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4313 
4314     if (G1TraceStringSymbolTableScrubbing) {
4315       gclog_or_tty->print_cr("Cleaned string and symbol table, "
4316                              "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4317                              "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4318                              strings_processed(), strings_removed(),
4319                              symbols_processed(), symbols_removed());
4320     }
4321   }
4322 
4323   void work(uint worker_id) {
4324     int strings_processed = 0;
4325     int strings_removed = 0;
4326     int symbols_processed = 0;
4327     int symbols_removed = 0;
4328     if (_process_strings) {
4329       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4330       Atomic::add(strings_processed, &_strings_processed);
4331       Atomic::add(strings_removed, &_strings_removed);
4332     }
4333     if (_process_symbols) {
4334       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4335       Atomic::add(symbols_processed, &_symbols_processed);
4336       Atomic::add(symbols_removed, &_symbols_removed);
4337     }
4338   }
4339 
4340   size_t strings_processed() const { return (size_t)_strings_processed; }
4341   size_t strings_removed()   const { return (size_t)_strings_removed; }
4342 
4343   size_t symbols_processed() const { return (size_t)_symbols_processed; }
4344   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
4345 };
4346 
4347 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4348 private:
4349   static Monitor* _lock;
4350 
4351   BoolObjectClosure* const _is_alive;
4352   const bool               _unloading_occurred;
4353   const uint               _num_workers;
4354 
4355   // Variables used to claim nmethods.
4356   nmethod* _first_nmethod;
4357   volatile nmethod* _claimed_nmethod;
4358 
4359   // The list of nmethods that need to be processed by the second pass.
4360   volatile nmethod* _postponed_list;
4361   volatile uint     _num_entered_barrier;
4362 
4363  public:
4364   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4365       _is_alive(is_alive),
4366       _unloading_occurred(unloading_occurred),
4367       _num_workers(num_workers),
4368       _first_nmethod(NULL),
4369       _claimed_nmethod(NULL),
4370       _postponed_list(NULL),
4371       _num_entered_barrier(0)
4372   {
4373     nmethod::increase_unloading_clock();
4374     // Get first alive nmethod
4375     NMethodIterator iter = NMethodIterator();
4376     if(iter.next_alive()) {
4377       _first_nmethod = iter.method();
4378     }
4379     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4380   }
4381 
4382   ~G1CodeCacheUnloadingTask() {
4383     CodeCache::verify_clean_inline_caches();
4384 
4385     CodeCache::set_needs_cache_clean(false);
4386     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4387 
4388     CodeCache::verify_icholder_relocations();
4389   }
4390 
4391  private:
4392   void add_to_postponed_list(nmethod* nm) {
4393       nmethod* old;
4394       do {
4395         old = (nmethod*)_postponed_list;
4396         nm->set_unloading_next(old);
4397       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4398   }
4399 
4400   void clean_nmethod(nmethod* nm) {
4401     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4402 
4403     if (postponed) {
4404       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4405       add_to_postponed_list(nm);
4406     }
4407 
4408     // Mark that this thread has been cleaned/unloaded.
4409     // After this call, it will be safe to ask if this nmethod was unloaded or not.
4410     nm->set_unloading_clock(nmethod::global_unloading_clock());
4411   }
4412 
4413   void clean_nmethod_postponed(nmethod* nm) {
4414     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4415   }
4416 
4417   static const int MaxClaimNmethods = 16;
4418 
4419   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4420     nmethod* first;
4421     NMethodIterator last;
4422 
4423     do {
4424       *num_claimed_nmethods = 0;
4425 
4426       first = (nmethod*)_claimed_nmethod;
4427       last = NMethodIterator(first);
4428 
4429       if (first != NULL) {
4430 
4431         for (int i = 0; i < MaxClaimNmethods; i++) {
4432           if (!last.next_alive()) {
4433             break;
4434           }
4435           claimed_nmethods[i] = last.method();
4436           (*num_claimed_nmethods)++;
4437         }
4438       }
4439 
4440     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4441   }
4442 
4443   nmethod* claim_postponed_nmethod() {
4444     nmethod* claim;
4445     nmethod* next;
4446 
4447     do {
4448       claim = (nmethod*)_postponed_list;
4449       if (claim == NULL) {
4450         return NULL;
4451       }
4452 
4453       next = claim->unloading_next();
4454 
4455     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4456 
4457     return claim;
4458   }
4459 
4460  public:
4461   // Mark that we're done with the first pass of nmethod cleaning.
4462   void barrier_mark(uint worker_id) {
4463     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4464     _num_entered_barrier++;
4465     if (_num_entered_barrier == _num_workers) {
4466       ml.notify_all();
4467     }
4468   }
4469 
4470   // See if we have to wait for the other workers to
4471   // finish their first-pass nmethod cleaning work.
4472   void barrier_wait(uint worker_id) {
4473     if (_num_entered_barrier < _num_workers) {
4474       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4475       while (_num_entered_barrier < _num_workers) {
4476           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4477       }
4478     }
4479   }
4480 
4481   // Cleaning and unloading of nmethods. Some work has to be postponed
4482   // to the second pass, when we know which nmethods survive.
4483   void work_first_pass(uint worker_id) {
4484     // The first nmethods is claimed by the first worker.
4485     if (worker_id == 0 && _first_nmethod != NULL) {
4486       clean_nmethod(_first_nmethod);
4487       _first_nmethod = NULL;
4488     }
4489 
4490     int num_claimed_nmethods;
4491     nmethod* claimed_nmethods[MaxClaimNmethods];
4492 
4493     while (true) {
4494       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4495 
4496       if (num_claimed_nmethods == 0) {
4497         break;
4498       }
4499 
4500       for (int i = 0; i < num_claimed_nmethods; i++) {
4501         clean_nmethod(claimed_nmethods[i]);
4502       }
4503     }
4504   }
4505 
4506   void work_second_pass(uint worker_id) {
4507     nmethod* nm;
4508     // Take care of postponed nmethods.
4509     while ((nm = claim_postponed_nmethod()) != NULL) {
4510       clean_nmethod_postponed(nm);
4511     }
4512   }
4513 };
4514 
4515 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4516 
4517 class G1KlassCleaningTask : public StackObj {
4518   BoolObjectClosure*                      _is_alive;
4519   volatile jint                           _clean_klass_tree_claimed;
4520   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4521 
4522  public:
4523   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4524       _is_alive(is_alive),
4525       _clean_klass_tree_claimed(0),
4526       _klass_iterator() {
4527   }
4528 
4529  private:
4530   bool claim_clean_klass_tree_task() {
4531     if (_clean_klass_tree_claimed) {
4532       return false;
4533     }
4534 
4535     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4536   }
4537 
4538   InstanceKlass* claim_next_klass() {
4539     Klass* klass;
4540     do {
4541       klass =_klass_iterator.next_klass();
4542     } while (klass != NULL && !klass->is_instance_klass());
4543 
4544     // this can be null so don't call InstanceKlass::cast
4545     return static_cast<InstanceKlass*>(klass);
4546   }
4547 
4548 public:
4549 
4550   void clean_klass(InstanceKlass* ik) {
4551     ik->clean_weak_instanceklass_links(_is_alive);
4552   }
4553 
4554   void work() {
4555     ResourceMark rm;
4556 
4557     // One worker will clean the subklass/sibling klass tree.
4558     if (claim_clean_klass_tree_task()) {
4559       Klass::clean_subklass_tree(_is_alive);
4560     }
4561 
4562     // All workers will help cleaning the classes,
4563     InstanceKlass* klass;
4564     while ((klass = claim_next_klass()) != NULL) {
4565       clean_klass(klass);
4566     }
4567   }
4568 };
4569 
4570 // To minimize the remark pause times, the tasks below are done in parallel.
4571 class G1ParallelCleaningTask : public AbstractGangTask {
4572 private:
4573   G1StringSymbolTableUnlinkTask _string_symbol_task;
4574   G1CodeCacheUnloadingTask      _code_cache_task;
4575   G1KlassCleaningTask           _klass_cleaning_task;
4576 
4577 public:
4578   // The constructor is run in the VMThread.
4579   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4580       AbstractGangTask("Parallel Cleaning"),
4581       _string_symbol_task(is_alive, process_strings, process_symbols),
4582       _code_cache_task(num_workers, is_alive, unloading_occurred),
4583       _klass_cleaning_task(is_alive) {
4584   }
4585 
4586   // The parallel work done by all worker threads.
4587   void work(uint worker_id) {
4588     // Do first pass of code cache cleaning.
4589     _code_cache_task.work_first_pass(worker_id);
4590 
4591     // Let the threads mark that the first pass is done.
4592     _code_cache_task.barrier_mark(worker_id);
4593 
4594     // Clean the Strings and Symbols.
4595     _string_symbol_task.work(worker_id);
4596 
4597     // Wait for all workers to finish the first code cache cleaning pass.
4598     _code_cache_task.barrier_wait(worker_id);
4599 
4600     // Do the second code cache cleaning work, which realize on
4601     // the liveness information gathered during the first pass.
4602     _code_cache_task.work_second_pass(worker_id);
4603 
4604     // Clean all klasses that were not unloaded.
4605     _klass_cleaning_task.work();
4606   }
4607 };
4608 
4609 
4610 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4611                                         bool process_strings,
4612                                         bool process_symbols,
4613                                         bool class_unloading_occurred) {
4614   uint n_workers = workers()->active_workers();
4615 
4616   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4617                                         n_workers, class_unloading_occurred);
4618   workers()->run_task(&g1_unlink_task);
4619 }
4620 
4621 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4622                                                      bool process_strings, bool process_symbols) {
4623   {
4624     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4625     workers()->run_task(&g1_unlink_task);
4626   }
4627 
4628   if (G1StringDedup::is_enabled()) {
4629     G1StringDedup::unlink(is_alive);
4630   }
4631 }
4632 
4633 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4634  private:
4635   DirtyCardQueueSet* _queue;
4636  public:
4637   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4638 
4639   virtual void work(uint worker_id) {
4640     G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4641     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4642 
4643     RedirtyLoggedCardTableEntryClosure cl;
4644     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4645 
4646     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4647   }
4648 };
4649 
4650 void G1CollectedHeap::redirty_logged_cards() {
4651   double redirty_logged_cards_start = os::elapsedTime();
4652 
4653   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4654   dirty_card_queue_set().reset_for_par_iteration();
4655   workers()->run_task(&redirty_task);
4656 
4657   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4658   dcq.merge_bufferlists(&dirty_card_queue_set());
4659   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4660 
4661   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4662 }
4663 
4664 // Weak Reference Processing support
4665 
4666 // An always "is_alive" closure that is used to preserve referents.
4667 // If the object is non-null then it's alive.  Used in the preservation
4668 // of referent objects that are pointed to by reference objects
4669 // discovered by the CM ref processor.
4670 class G1AlwaysAliveClosure: public BoolObjectClosure {
4671   G1CollectedHeap* _g1;
4672 public:
4673   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4674   bool do_object_b(oop p) {
4675     if (p != NULL) {
4676       return true;
4677     }
4678     return false;
4679   }
4680 };
4681 
4682 bool G1STWIsAliveClosure::do_object_b(oop p) {
4683   // An object is reachable if it is outside the collection set,
4684   // or is inside and copied.
4685   return !_g1->is_in_cset(p) || p->is_forwarded();
4686 }
4687 
4688 // Non Copying Keep Alive closure
4689 class G1KeepAliveClosure: public OopClosure {
4690   G1CollectedHeap* _g1;
4691 public:
4692   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4693   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4694   void do_oop(oop* p) {
4695     oop obj = *p;
4696     assert(obj != NULL, "the caller should have filtered out NULL values");
4697 
4698     const InCSetState cset_state = _g1->in_cset_state(obj);
4699     if (!cset_state.is_in_cset_or_humongous()) {
4700       return;
4701     }
4702     if (cset_state.is_in_cset()) {
4703       assert( obj->is_forwarded(), "invariant" );
4704       *p = obj->forwardee();
4705     } else {
4706       assert(!obj->is_forwarded(), "invariant" );
4707       assert(cset_state.is_humongous(),
4708              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4709       _g1->set_humongous_is_live(obj);
4710     }
4711   }
4712 };
4713 
4714 // Copying Keep Alive closure - can be called from both
4715 // serial and parallel code as long as different worker
4716 // threads utilize different G1ParScanThreadState instances
4717 // and different queues.
4718 
4719 class G1CopyingKeepAliveClosure: public OopClosure {
4720   G1CollectedHeap*         _g1h;
4721   OopClosure*              _copy_non_heap_obj_cl;
4722   G1ParScanThreadState*    _par_scan_state;
4723 
4724 public:
4725   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4726                             OopClosure* non_heap_obj_cl,
4727                             G1ParScanThreadState* pss):
4728     _g1h(g1h),
4729     _copy_non_heap_obj_cl(non_heap_obj_cl),
4730     _par_scan_state(pss)
4731   {}
4732 
4733   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4734   virtual void do_oop(      oop* p) { do_oop_work(p); }
4735 
4736   template <class T> void do_oop_work(T* p) {
4737     oop obj = oopDesc::load_decode_heap_oop(p);
4738 
4739     if (_g1h->is_in_cset_or_humongous(obj)) {
4740       // If the referent object has been forwarded (either copied
4741       // to a new location or to itself in the event of an
4742       // evacuation failure) then we need to update the reference
4743       // field and, if both reference and referent are in the G1
4744       // heap, update the RSet for the referent.
4745       //
4746       // If the referent has not been forwarded then we have to keep
4747       // it alive by policy. Therefore we have copy the referent.
4748       //
4749       // If the reference field is in the G1 heap then we can push
4750       // on the PSS queue. When the queue is drained (after each
4751       // phase of reference processing) the object and it's followers
4752       // will be copied, the reference field set to point to the
4753       // new location, and the RSet updated. Otherwise we need to
4754       // use the the non-heap or metadata closures directly to copy
4755       // the referent object and update the pointer, while avoiding
4756       // updating the RSet.
4757 
4758       if (_g1h->is_in_g1_reserved(p)) {
4759         _par_scan_state->push_on_queue(p);
4760       } else {
4761         assert(!Metaspace::contains((const void*)p),
4762                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4763         _copy_non_heap_obj_cl->do_oop(p);
4764       }
4765     }
4766   }
4767 };
4768 
4769 // Serial drain queue closure. Called as the 'complete_gc'
4770 // closure for each discovered list in some of the
4771 // reference processing phases.
4772 
4773 class G1STWDrainQueueClosure: public VoidClosure {
4774 protected:
4775   G1CollectedHeap* _g1h;
4776   G1ParScanThreadState* _par_scan_state;
4777 
4778   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4779 
4780 public:
4781   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4782     _g1h(g1h),
4783     _par_scan_state(pss)
4784   { }
4785 
4786   void do_void() {
4787     G1ParScanThreadState* const pss = par_scan_state();
4788     pss->trim_queue();
4789   }
4790 };
4791 
4792 // Parallel Reference Processing closures
4793 
4794 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4795 // processing during G1 evacuation pauses.
4796 
4797 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4798 private:
4799   G1CollectedHeap*          _g1h;
4800   G1ParScanThreadStateSet*  _pss;
4801   RefToScanQueueSet*        _queues;
4802   WorkGang*                 _workers;
4803   uint                      _active_workers;
4804 
4805 public:
4806   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4807                            G1ParScanThreadStateSet* per_thread_states,
4808                            WorkGang* workers,
4809                            RefToScanQueueSet *task_queues,
4810                            uint n_workers) :
4811     _g1h(g1h),
4812     _pss(per_thread_states),
4813     _queues(task_queues),
4814     _workers(workers),
4815     _active_workers(n_workers)
4816   {
4817     assert(n_workers > 0, "shouldn't call this otherwise");
4818   }
4819 
4820   // Executes the given task using concurrent marking worker threads.
4821   virtual void execute(ProcessTask& task);
4822   virtual void execute(EnqueueTask& task);
4823 };
4824 
4825 // Gang task for possibly parallel reference processing
4826 
4827 class G1STWRefProcTaskProxy: public AbstractGangTask {
4828   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4829   ProcessTask&     _proc_task;
4830   G1CollectedHeap* _g1h;
4831   G1ParScanThreadStateSet* _pss;
4832   RefToScanQueueSet* _task_queues;
4833   ParallelTaskTerminator* _terminator;
4834 
4835 public:
4836   G1STWRefProcTaskProxy(ProcessTask& proc_task,
4837                         G1CollectedHeap* g1h,
4838                         G1ParScanThreadStateSet* per_thread_states,
4839                         RefToScanQueueSet *task_queues,
4840                         ParallelTaskTerminator* terminator) :
4841     AbstractGangTask("Process reference objects in parallel"),
4842     _proc_task(proc_task),
4843     _g1h(g1h),
4844     _pss(per_thread_states),
4845     _task_queues(task_queues),
4846     _terminator(terminator)
4847   {}
4848 
4849   virtual void work(uint worker_id) {
4850     // The reference processing task executed by a single worker.
4851     ResourceMark rm;
4852     HandleMark   hm;
4853 
4854     G1STWIsAliveClosure is_alive(_g1h);
4855 
4856     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4857     pss->set_ref_processor(NULL);
4858 
4859     // Keep alive closure.
4860     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4861 
4862     // Complete GC closure
4863     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4864 
4865     // Call the reference processing task's work routine.
4866     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4867 
4868     // Note we cannot assert that the refs array is empty here as not all
4869     // of the processing tasks (specifically phase2 - pp2_work) execute
4870     // the complete_gc closure (which ordinarily would drain the queue) so
4871     // the queue may not be empty.
4872   }
4873 };
4874 
4875 // Driver routine for parallel reference processing.
4876 // Creates an instance of the ref processing gang
4877 // task and has the worker threads execute it.
4878 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4879   assert(_workers != NULL, "Need parallel worker threads.");
4880 
4881   ParallelTaskTerminator terminator(_active_workers, _queues);
4882   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4883 
4884   _workers->run_task(&proc_task_proxy);
4885 }
4886 
4887 // Gang task for parallel reference enqueueing.
4888 
4889 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4890   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4891   EnqueueTask& _enq_task;
4892 
4893 public:
4894   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4895     AbstractGangTask("Enqueue reference objects in parallel"),
4896     _enq_task(enq_task)
4897   { }
4898 
4899   virtual void work(uint worker_id) {
4900     _enq_task.work(worker_id);
4901   }
4902 };
4903 
4904 // Driver routine for parallel reference enqueueing.
4905 // Creates an instance of the ref enqueueing gang
4906 // task and has the worker threads execute it.
4907 
4908 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4909   assert(_workers != NULL, "Need parallel worker threads.");
4910 
4911   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4912 
4913   _workers->run_task(&enq_task_proxy);
4914 }
4915 
4916 // End of weak reference support closures
4917 
4918 // Abstract task used to preserve (i.e. copy) any referent objects
4919 // that are in the collection set and are pointed to by reference
4920 // objects discovered by the CM ref processor.
4921 
4922 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4923 protected:
4924   G1CollectedHeap*         _g1h;
4925   G1ParScanThreadStateSet* _pss;
4926   RefToScanQueueSet*       _queues;
4927   ParallelTaskTerminator   _terminator;
4928   uint                     _n_workers;
4929 
4930 public:
4931   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4932     AbstractGangTask("ParPreserveCMReferents"),
4933     _g1h(g1h),
4934     _pss(per_thread_states),
4935     _queues(task_queues),
4936     _terminator(workers, _queues),
4937     _n_workers(workers)
4938   { }
4939 
4940   void work(uint worker_id) {
4941     ResourceMark rm;
4942     HandleMark   hm;
4943 
4944     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4945     pss->set_ref_processor(NULL);
4946     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4947 
4948     // Is alive closure
4949     G1AlwaysAliveClosure always_alive(_g1h);
4950 
4951     // Copying keep alive closure. Applied to referent objects that need
4952     // to be copied.
4953     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4954 
4955     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4956 
4957     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4958     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4959 
4960     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4961     // So this must be true - but assert just in case someone decides to
4962     // change the worker ids.
4963     assert(worker_id < limit, "sanity");
4964     assert(!rp->discovery_is_atomic(), "check this code");
4965 
4966     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4967     for (uint idx = worker_id; idx < limit; idx += stride) {
4968       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4969 
4970       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4971       while (iter.has_next()) {
4972         // Since discovery is not atomic for the CM ref processor, we
4973         // can see some null referent objects.
4974         iter.load_ptrs(DEBUG_ONLY(true));
4975         oop ref = iter.obj();
4976 
4977         // This will filter nulls.
4978         if (iter.is_referent_alive()) {
4979           iter.make_referent_alive();
4980         }
4981         iter.move_to_next();
4982       }
4983     }
4984 
4985     // Drain the queue - which may cause stealing
4986     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4987     drain_queue.do_void();
4988     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4989     assert(pss->queue_is_empty(), "should be");
4990   }
4991 };
4992 
4993 // Weak Reference processing during an evacuation pause (part 1).
4994 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4995   double ref_proc_start = os::elapsedTime();
4996 
4997   ReferenceProcessor* rp = _ref_processor_stw;
4998   assert(rp->discovery_enabled(), "should have been enabled");
4999 
5000   // Any reference objects, in the collection set, that were 'discovered'
5001   // by the CM ref processor should have already been copied (either by
5002   // applying the external root copy closure to the discovered lists, or
5003   // by following an RSet entry).
5004   //
5005   // But some of the referents, that are in the collection set, that these
5006   // reference objects point to may not have been copied: the STW ref
5007   // processor would have seen that the reference object had already
5008   // been 'discovered' and would have skipped discovering the reference,
5009   // but would not have treated the reference object as a regular oop.
5010   // As a result the copy closure would not have been applied to the
5011   // referent object.
5012   //
5013   // We need to explicitly copy these referent objects - the references
5014   // will be processed at the end of remarking.
5015   //
5016   // We also need to do this copying before we process the reference
5017   // objects discovered by the STW ref processor in case one of these
5018   // referents points to another object which is also referenced by an
5019   // object discovered by the STW ref processor.
5020 
5021   uint no_of_gc_workers = workers()->active_workers();
5022 
5023   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5024                                                  per_thread_states,
5025                                                  no_of_gc_workers,
5026                                                  _task_queues);
5027 
5028   workers()->run_task(&keep_cm_referents);
5029 
5030   // Closure to test whether a referent is alive.
5031   G1STWIsAliveClosure is_alive(this);
5032 
5033   // Even when parallel reference processing is enabled, the processing
5034   // of JNI refs is serial and performed serially by the current thread
5035   // rather than by a worker. The following PSS will be used for processing
5036   // JNI refs.
5037 
5038   // Use only a single queue for this PSS.
5039   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
5040   pss->set_ref_processor(NULL);
5041   assert(pss->queue_is_empty(), "pre-condition");
5042 
5043   // Keep alive closure.
5044   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5045 
5046   // Serial Complete GC closure
5047   G1STWDrainQueueClosure drain_queue(this, pss);
5048 
5049   // Setup the soft refs policy...
5050   rp->setup_policy(false);
5051 
5052   ReferenceProcessorStats stats;
5053   if (!rp->processing_is_mt()) {
5054     // Serial reference processing...
5055     stats = rp->process_discovered_references(&is_alive,
5056                                               &keep_alive,
5057                                               &drain_queue,
5058                                               NULL,
5059                                               _gc_timer_stw);
5060   } else {
5061     // Parallel reference processing
5062     assert(rp->num_q() == no_of_gc_workers, "sanity");
5063     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5064 
5065     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5066     stats = rp->process_discovered_references(&is_alive,
5067                                               &keep_alive,
5068                                               &drain_queue,
5069                                               &par_task_executor,
5070                                               _gc_timer_stw);
5071   }
5072 
5073   _gc_tracer_stw->report_gc_reference_stats(stats);
5074 
5075   // We have completed copying any necessary live referent objects.
5076   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5077 
5078   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5079   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5080 }
5081 
5082 // Weak Reference processing during an evacuation pause (part 2).
5083 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5084   double ref_enq_start = os::elapsedTime();
5085 
5086   ReferenceProcessor* rp = _ref_processor_stw;
5087   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5088 
5089   // Now enqueue any remaining on the discovered lists on to
5090   // the pending list.
5091   if (!rp->processing_is_mt()) {
5092     // Serial reference processing...
5093     rp->enqueue_discovered_references();
5094   } else {
5095     // Parallel reference enqueueing
5096 
5097     uint n_workers = workers()->active_workers();
5098 
5099     assert(rp->num_q() == n_workers, "sanity");
5100     assert(n_workers <= rp->max_num_q(), "sanity");
5101 
5102     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5103     rp->enqueue_discovered_references(&par_task_executor);
5104   }
5105 
5106   rp->verify_no_references_recorded();
5107   assert(!rp->discovery_enabled(), "should have been disabled");
5108 
5109   // FIXME
5110   // CM's reference processing also cleans up the string and symbol tables.
5111   // Should we do that here also? We could, but it is a serial operation
5112   // and could significantly increase the pause time.
5113 
5114   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5115   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5116 }
5117 
5118 void G1CollectedHeap::pre_evacuate_collection_set() {
5119   _expand_heap_after_alloc_failure = true;
5120   _evacuation_failed = false;
5121 
5122   // Disable the hot card cache.
5123   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5124   hot_card_cache->reset_hot_cache_claimed_index();
5125   hot_card_cache->set_use_cache(false);
5126 
5127 }
5128 
5129 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5130   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5131 
5132   // Should G1EvacuationFailureALot be in effect for this GC?
5133   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5134 
5135   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5136   double start_par_time_sec = os::elapsedTime();
5137   double end_par_time_sec;
5138 
5139   {
5140     const uint n_workers = workers()->active_workers();
5141     G1RootProcessor root_processor(this, n_workers);
5142     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5143     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5144     if (collector_state()->during_initial_mark_pause()) {
5145       ClassLoaderDataGraph::clear_claimed_marks();
5146     }
5147 
5148     // The individual threads will set their evac-failure closures.
5149     if (PrintTerminationStats) {
5150       print_termination_stats_hdr(gclog_or_tty);
5151     }
5152 
5153     workers()->run_task(&g1_par_task);
5154     end_par_time_sec = os::elapsedTime();
5155 
5156     // Closing the inner scope will execute the destructor
5157     // for the G1RootProcessor object. We record the current
5158     // elapsed time before closing the scope so that time
5159     // taken for the destructor is NOT included in the
5160     // reported parallel time.
5161   }
5162 
5163   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5164 
5165   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5166   phase_times->record_par_time(par_time_ms);
5167 
5168   double code_root_fixup_time_ms =
5169         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5170   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5171 
5172   // Process any discovered reference objects - we have
5173   // to do this _before_ we retire the GC alloc regions
5174   // as we may have to copy some 'reachable' referent
5175   // objects (and their reachable sub-graphs) that were
5176   // not copied during the pause.
5177   process_discovered_references(per_thread_states);
5178 
5179   if (G1StringDedup::is_enabled()) {
5180     double fixup_start = os::elapsedTime();
5181 
5182     G1STWIsAliveClosure is_alive(this);
5183     G1KeepAliveClosure keep_alive(this);
5184     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5185 
5186     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5187     phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5188   }
5189 
5190   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5191 
5192   if (evacuation_failed()) {
5193     remove_self_forwarding_pointers();
5194 
5195     // Reset the G1EvacuationFailureALot counters and flags
5196     // Note: the values are reset only when an actual
5197     // evacuation failure occurs.
5198     NOT_PRODUCT(reset_evacuation_should_fail();)
5199   }
5200 
5201   // Enqueue any remaining references remaining on the STW
5202   // reference processor's discovered lists. We need to do
5203   // this after the card table is cleaned (and verified) as
5204   // the act of enqueueing entries on to the pending list
5205   // will log these updates (and dirty their associated
5206   // cards). We need these updates logged to update any
5207   // RSets.
5208   enqueue_discovered_references(per_thread_states);
5209 }
5210 
5211 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5212   _allocator->release_gc_alloc_regions(evacuation_info);
5213 
5214   per_thread_states->flush();
5215 
5216   record_obj_copy_mem_stats();
5217 
5218   _survivor_evac_stats.adjust_desired_plab_sz();
5219   _old_evac_stats.adjust_desired_plab_sz();
5220 
5221   // Reset and re-enable the hot card cache.
5222   // Note the counts for the cards in the regions in the
5223   // collection set are reset when the collection set is freed.
5224   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5225   hot_card_cache->reset_hot_cache();
5226   hot_card_cache->set_use_cache(true);
5227 
5228   purge_code_root_memory();
5229 
5230   redirty_logged_cards();
5231 #if defined(COMPILER2) || INCLUDE_JVMCI
5232   DerivedPointerTable::update_pointers();
5233 #endif
5234 }
5235 
5236 void G1CollectedHeap::record_obj_copy_mem_stats() {
5237   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5238                                                create_g1_evac_summary(&_old_evac_stats));
5239 }
5240 
5241 void G1CollectedHeap::free_region(HeapRegion* hr,
5242                                   FreeRegionList* free_list,
5243                                   bool par,
5244                                   bool locked) {
5245   assert(!hr->is_free(), "the region should not be free");
5246   assert(!hr->is_empty(), "the region should not be empty");
5247   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5248   assert(free_list != NULL, "pre-condition");
5249 
5250   if (G1VerifyBitmaps) {
5251     MemRegion mr(hr->bottom(), hr->end());
5252     concurrent_mark()->clearRangePrevBitmap(mr);
5253   }
5254 
5255   // Clear the card counts for this region.
5256   // Note: we only need to do this if the region is not young
5257   // (since we don't refine cards in young regions).
5258   if (!hr->is_young()) {
5259     _cg1r->hot_card_cache()->reset_card_counts(hr);
5260   }
5261   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5262   free_list->add_ordered(hr);
5263 }
5264 
5265 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5266                                             FreeRegionList* free_list,
5267                                             bool par) {
5268   assert(hr->is_humongous(), "this is only for humongous regions");
5269   assert(free_list != NULL, "pre-condition");
5270   hr->clear_humongous();
5271   free_region(hr, free_list, par);
5272 }
5273 
5274 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5275                                            const HeapRegionSetCount& humongous_regions_removed) {
5276   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5277     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5278     _old_set.bulk_remove(old_regions_removed);
5279     _humongous_set.bulk_remove(humongous_regions_removed);
5280   }
5281 
5282 }
5283 
5284 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5285   assert(list != NULL, "list can't be null");
5286   if (!list->is_empty()) {
5287     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5288     _hrm.insert_list_into_free_list(list);
5289   }
5290 }
5291 
5292 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5293   decrease_used(bytes);
5294 }
5295 
5296 class G1ParCleanupCTTask : public AbstractGangTask {
5297   G1SATBCardTableModRefBS* _ct_bs;
5298   G1CollectedHeap* _g1h;
5299   HeapRegion* volatile _su_head;
5300 public:
5301   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5302                      G1CollectedHeap* g1h) :
5303     AbstractGangTask("G1 Par Cleanup CT Task"),
5304     _ct_bs(ct_bs), _g1h(g1h) { }
5305 
5306   void work(uint worker_id) {
5307     HeapRegion* r;
5308     while (r = _g1h->pop_dirty_cards_region()) {
5309       clear_cards(r);
5310     }
5311   }
5312 
5313   void clear_cards(HeapRegion* r) {
5314     // Cards of the survivors should have already been dirtied.
5315     if (!r->is_survivor()) {
5316       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5317     }
5318   }
5319 };
5320 
5321 #ifndef PRODUCT
5322 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5323   G1CollectedHeap* _g1h;
5324   G1SATBCardTableModRefBS* _ct_bs;
5325 public:
5326   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5327     : _g1h(g1h), _ct_bs(ct_bs) { }
5328   virtual bool doHeapRegion(HeapRegion* r) {
5329     if (r->is_survivor()) {
5330       _g1h->verify_dirty_region(r);
5331     } else {
5332       _g1h->verify_not_dirty_region(r);
5333     }
5334     return false;
5335   }
5336 };
5337 
5338 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5339   // All of the region should be clean.
5340   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5341   MemRegion mr(hr->bottom(), hr->end());
5342   ct_bs->verify_not_dirty_region(mr);
5343 }
5344 
5345 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5346   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5347   // dirty allocated blocks as they allocate them. The thread that
5348   // retires each region and replaces it with a new one will do a
5349   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5350   // not dirty that area (one less thing to have to do while holding
5351   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5352   // is dirty.
5353   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5354   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5355   if (hr->is_young()) {
5356     ct_bs->verify_g1_young_region(mr);
5357   } else {
5358     ct_bs->verify_dirty_region(mr);
5359   }
5360 }
5361 
5362 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5363   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5364   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5365     verify_dirty_region(hr);
5366   }
5367 }
5368 
5369 void G1CollectedHeap::verify_dirty_young_regions() {
5370   verify_dirty_young_list(_young_list->first_region());
5371 }
5372 
5373 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5374                                                HeapWord* tams, HeapWord* end) {
5375   guarantee(tams <= end,
5376             "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5377   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5378   if (result < end) {
5379     gclog_or_tty->cr();
5380     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5381                            bitmap_name, p2i(result));
5382     gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5383                            bitmap_name, p2i(tams), p2i(end));
5384     return false;
5385   }
5386   return true;
5387 }
5388 
5389 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5390   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5391   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5392 
5393   HeapWord* bottom = hr->bottom();
5394   HeapWord* ptams  = hr->prev_top_at_mark_start();
5395   HeapWord* ntams  = hr->next_top_at_mark_start();
5396   HeapWord* end    = hr->end();
5397 
5398   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5399 
5400   bool res_n = true;
5401   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5402   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5403   // if we happen to be in that state.
5404   if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5405     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5406   }
5407   if (!res_p || !res_n) {
5408     gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5409                            HR_FORMAT_PARAMS(hr));
5410     gclog_or_tty->print_cr("#### Caller: %s", caller);
5411     return false;
5412   }
5413   return true;
5414 }
5415 
5416 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5417   if (!G1VerifyBitmaps) return;
5418 
5419   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5420 }
5421 
5422 class G1VerifyBitmapClosure : public HeapRegionClosure {
5423 private:
5424   const char* _caller;
5425   G1CollectedHeap* _g1h;
5426   bool _failures;
5427 
5428 public:
5429   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5430     _caller(caller), _g1h(g1h), _failures(false) { }
5431 
5432   bool failures() { return _failures; }
5433 
5434   virtual bool doHeapRegion(HeapRegion* hr) {
5435     bool result = _g1h->verify_bitmaps(_caller, hr);
5436     if (!result) {
5437       _failures = true;
5438     }
5439     return false;
5440   }
5441 };
5442 
5443 void G1CollectedHeap::check_bitmaps(const char* caller) {
5444   if (!G1VerifyBitmaps) return;
5445 
5446   G1VerifyBitmapClosure cl(caller, this);
5447   heap_region_iterate(&cl);
5448   guarantee(!cl.failures(), "bitmap verification");
5449 }
5450 
5451 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5452  private:
5453   bool _failures;
5454  public:
5455   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5456 
5457   virtual bool doHeapRegion(HeapRegion* hr) {
5458     uint i = hr->hrm_index();
5459     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5460     if (hr->is_humongous()) {
5461       if (hr->in_collection_set()) {
5462         gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5463         _failures = true;
5464         return true;
5465       }
5466       if (cset_state.is_in_cset()) {
5467         gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5468         _failures = true;
5469         return true;
5470       }
5471       if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5472         gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5473         _failures = true;
5474         return true;
5475       }
5476     } else {
5477       if (cset_state.is_humongous()) {
5478         gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5479         _failures = true;
5480         return true;
5481       }
5482       if (hr->in_collection_set() != cset_state.is_in_cset()) {
5483         gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5484                                hr->in_collection_set(), cset_state.value(), i);
5485         _failures = true;
5486         return true;
5487       }
5488       if (cset_state.is_in_cset()) {
5489         if (hr->is_young() != (cset_state.is_young())) {
5490           gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5491                                  hr->is_young(), cset_state.value(), i);
5492           _failures = true;
5493           return true;
5494         }
5495         if (hr->is_old() != (cset_state.is_old())) {
5496           gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5497                                  hr->is_old(), cset_state.value(), i);
5498           _failures = true;
5499           return true;
5500         }
5501       }
5502     }
5503     return false;
5504   }
5505 
5506   bool failures() const { return _failures; }
5507 };
5508 
5509 bool G1CollectedHeap::check_cset_fast_test() {
5510   G1CheckCSetFastTableClosure cl;
5511   _hrm.iterate(&cl);
5512   return !cl.failures();
5513 }
5514 #endif // PRODUCT
5515 
5516 void G1CollectedHeap::cleanUpCardTable() {
5517   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5518   double start = os::elapsedTime();
5519 
5520   {
5521     // Iterate over the dirty cards region list.
5522     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5523 
5524     workers()->run_task(&cleanup_task);
5525 #ifndef PRODUCT
5526     if (G1VerifyCTCleanup || VerifyAfterGC) {
5527       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5528       heap_region_iterate(&cleanup_verifier);
5529     }
5530 #endif
5531   }
5532 
5533   double elapsed = os::elapsedTime() - start;
5534   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5535 }
5536 
5537 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5538   size_t pre_used = 0;
5539   FreeRegionList local_free_list("Local List for CSet Freeing");
5540 
5541   double young_time_ms     = 0.0;
5542   double non_young_time_ms = 0.0;
5543 
5544   // Since the collection set is a superset of the the young list,
5545   // all we need to do to clear the young list is clear its
5546   // head and length, and unlink any young regions in the code below
5547   _young_list->clear();
5548 
5549   G1CollectorPolicy* policy = g1_policy();
5550 
5551   double start_sec = os::elapsedTime();
5552   bool non_young = true;
5553 
5554   HeapRegion* cur = cs_head;
5555   int age_bound = -1;
5556   size_t rs_lengths = 0;
5557 
5558   while (cur != NULL) {
5559     assert(!is_on_master_free_list(cur), "sanity");
5560     if (non_young) {
5561       if (cur->is_young()) {
5562         double end_sec = os::elapsedTime();
5563         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5564         non_young_time_ms += elapsed_ms;
5565 
5566         start_sec = os::elapsedTime();
5567         non_young = false;
5568       }
5569     } else {
5570       if (!cur->is_young()) {
5571         double end_sec = os::elapsedTime();
5572         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5573         young_time_ms += elapsed_ms;
5574 
5575         start_sec = os::elapsedTime();
5576         non_young = true;
5577       }
5578     }
5579 
5580     rs_lengths += cur->rem_set()->occupied_locked();
5581 
5582     HeapRegion* next = cur->next_in_collection_set();
5583     assert(cur->in_collection_set(), "bad CS");
5584     cur->set_next_in_collection_set(NULL);
5585     clear_in_cset(cur);
5586 
5587     if (cur->is_young()) {
5588       int index = cur->young_index_in_cset();
5589       assert(index != -1, "invariant");
5590       assert((uint) index < policy->young_cset_region_length(), "invariant");
5591       size_t words_survived = surviving_young_words[index];
5592       cur->record_surv_words_in_group(words_survived);
5593 
5594       // At this point the we have 'popped' cur from the collection set
5595       // (linked via next_in_collection_set()) but it is still in the
5596       // young list (linked via next_young_region()). Clear the
5597       // _next_young_region field.
5598       cur->set_next_young_region(NULL);
5599     } else {
5600       int index = cur->young_index_in_cset();
5601       assert(index == -1, "invariant");
5602     }
5603 
5604     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5605             (!cur->is_young() && cur->young_index_in_cset() == -1),
5606             "invariant" );
5607 
5608     if (!cur->evacuation_failed()) {
5609       MemRegion used_mr = cur->used_region();
5610 
5611       // And the region is empty.
5612       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5613       pre_used += cur->used();
5614       free_region(cur, &local_free_list, false /* par */, true /* locked */);
5615     } else {
5616       cur->uninstall_surv_rate_group();
5617       if (cur->is_young()) {
5618         cur->set_young_index_in_cset(-1);
5619       }
5620       cur->set_evacuation_failed(false);
5621       // The region is now considered to be old.
5622       cur->set_old();
5623       // Do some allocation statistics accounting. Regions that failed evacuation
5624       // are always made old, so there is no need to update anything in the young
5625       // gen statistics, but we need to update old gen statistics.
5626       size_t used_words = cur->marked_bytes() / HeapWordSize;
5627       _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5628       _old_set.add(cur);
5629       evacuation_info.increment_collectionset_used_after(cur->used());
5630     }
5631     cur = next;
5632   }
5633 
5634   evacuation_info.set_regions_freed(local_free_list.length());
5635   policy->record_max_rs_lengths(rs_lengths);
5636   policy->cset_regions_freed();
5637 
5638   double end_sec = os::elapsedTime();
5639   double elapsed_ms = (end_sec - start_sec) * 1000.0;
5640 
5641   if (non_young) {
5642     non_young_time_ms += elapsed_ms;
5643   } else {
5644     young_time_ms += elapsed_ms;
5645   }
5646 
5647   prepend_to_freelist(&local_free_list);
5648   decrement_summary_bytes(pre_used);
5649   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5650   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5651 }
5652 
5653 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5654  private:
5655   FreeRegionList* _free_region_list;
5656   HeapRegionSet* _proxy_set;
5657   HeapRegionSetCount _humongous_regions_removed;
5658   size_t _freed_bytes;
5659  public:
5660 
5661   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5662     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5663   }
5664 
5665   virtual bool doHeapRegion(HeapRegion* r) {
5666     if (!r->is_starts_humongous()) {
5667       return false;
5668     }
5669 
5670     G1CollectedHeap* g1h = G1CollectedHeap::heap();
5671 
5672     oop obj = (oop)r->bottom();
5673     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5674 
5675     // The following checks whether the humongous object is live are sufficient.
5676     // The main additional check (in addition to having a reference from the roots
5677     // or the young gen) is whether the humongous object has a remembered set entry.
5678     //
5679     // A humongous object cannot be live if there is no remembered set for it
5680     // because:
5681     // - there can be no references from within humongous starts regions referencing
5682     // the object because we never allocate other objects into them.
5683     // (I.e. there are no intra-region references that may be missed by the
5684     // remembered set)
5685     // - as soon there is a remembered set entry to the humongous starts region
5686     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5687     // until the end of a concurrent mark.
5688     //
5689     // It is not required to check whether the object has been found dead by marking
5690     // or not, in fact it would prevent reclamation within a concurrent cycle, as
5691     // all objects allocated during that time are considered live.
5692     // SATB marking is even more conservative than the remembered set.
5693     // So if at this point in the collection there is no remembered set entry,
5694     // nobody has a reference to it.
5695     // At the start of collection we flush all refinement logs, and remembered sets
5696     // are completely up-to-date wrt to references to the humongous object.
5697     //
5698     // Other implementation considerations:
5699     // - never consider object arrays at this time because they would pose
5700     // considerable effort for cleaning up the the remembered sets. This is
5701     // required because stale remembered sets might reference locations that
5702     // are currently allocated into.
5703     uint region_idx = r->hrm_index();
5704     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5705         !r->rem_set()->is_empty()) {
5706 
5707       if (G1TraceEagerReclaimHumongousObjects) {
5708         gclog_or_tty->print_cr("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",
5709                                region_idx,
5710                                (size_t)obj->size() * HeapWordSize,
5711                                p2i(r->bottom()),
5712                                r->rem_set()->occupied(),
5713                                r->rem_set()->strong_code_roots_list_length(),
5714                                next_bitmap->isMarked(r->bottom()),
5715                                g1h->is_humongous_reclaim_candidate(region_idx),
5716                                obj->is_typeArray()
5717                               );
5718       }
5719 
5720       return false;
5721     }
5722 
5723     guarantee(obj->is_typeArray(),
5724               "Only eagerly reclaiming type arrays is supported, but the object "
5725               PTR_FORMAT " is not.", p2i(r->bottom()));
5726 
5727     if (G1TraceEagerReclaimHumongousObjects) {
5728       gclog_or_tty->print_cr("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",
5729                              region_idx,
5730                              (size_t)obj->size() * HeapWordSize,
5731                              p2i(r->bottom()),
5732                              r->rem_set()->occupied(),
5733                              r->rem_set()->strong_code_roots_list_length(),
5734                              next_bitmap->isMarked(r->bottom()),
5735                              g1h->is_humongous_reclaim_candidate(region_idx),
5736                              obj->is_typeArray()
5737                             );
5738     }
5739     // Need to clear mark bit of the humongous object if already set.
5740     if (next_bitmap->isMarked(r->bottom())) {
5741       next_bitmap->clear(r->bottom());
5742     }
5743     do {
5744       HeapRegion* next = g1h->next_region_in_humongous(r);
5745       _freed_bytes += r->used();
5746       r->set_containing_set(NULL);
5747       _humongous_regions_removed.increment(1u, r->capacity());
5748       g1h->free_humongous_region(r, _free_region_list, false);
5749       r = next;
5750     } while (r != NULL);
5751 
5752     return false;
5753   }
5754 
5755   HeapRegionSetCount& humongous_free_count() {
5756     return _humongous_regions_removed;
5757   }
5758 
5759   size_t bytes_freed() const {
5760     return _freed_bytes;
5761   }
5762 
5763   size_t humongous_reclaimed() const {
5764     return _humongous_regions_removed.length();
5765   }
5766 };
5767 
5768 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5769   assert_at_safepoint(true);
5770 
5771   if (!G1EagerReclaimHumongousObjects ||
5772       (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5773     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5774     return;
5775   }
5776 
5777   double start_time = os::elapsedTime();
5778 
5779   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5780 
5781   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5782   heap_region_iterate(&cl);
5783 
5784   HeapRegionSetCount empty_set;
5785   remove_from_old_sets(empty_set, cl.humongous_free_count());
5786 
5787   G1HRPrinter* hrp = hr_printer();
5788   if (hrp->is_active()) {
5789     FreeRegionListIterator iter(&local_cleanup_list);
5790     while (iter.more_available()) {
5791       HeapRegion* hr = iter.get_next();
5792       hrp->cleanup(hr);
5793     }
5794   }
5795 
5796   prepend_to_freelist(&local_cleanup_list);
5797   decrement_summary_bytes(cl.bytes_freed());
5798 
5799   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5800                                                                     cl.humongous_reclaimed());
5801 }
5802 
5803 // This routine is similar to the above but does not record
5804 // any policy statistics or update free lists; we are abandoning
5805 // the current incremental collection set in preparation of a
5806 // full collection. After the full GC we will start to build up
5807 // the incremental collection set again.
5808 // This is only called when we're doing a full collection
5809 // and is immediately followed by the tearing down of the young list.
5810 
5811 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5812   HeapRegion* cur = cs_head;
5813 
5814   while (cur != NULL) {
5815     HeapRegion* next = cur->next_in_collection_set();
5816     assert(cur->in_collection_set(), "bad CS");
5817     cur->set_next_in_collection_set(NULL);
5818     clear_in_cset(cur);
5819     cur->set_young_index_in_cset(-1);
5820     cur = next;
5821   }
5822 }
5823 
5824 void G1CollectedHeap::set_free_regions_coming() {
5825   if (G1ConcRegionFreeingVerbose) {
5826     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5827                            "setting free regions coming");
5828   }
5829 
5830   assert(!free_regions_coming(), "pre-condition");
5831   _free_regions_coming = true;
5832 }
5833 
5834 void G1CollectedHeap::reset_free_regions_coming() {
5835   assert(free_regions_coming(), "pre-condition");
5836 
5837   {
5838     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5839     _free_regions_coming = false;
5840     SecondaryFreeList_lock->notify_all();
5841   }
5842 
5843   if (G1ConcRegionFreeingVerbose) {
5844     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5845                            "reset free regions coming");
5846   }
5847 }
5848 
5849 void G1CollectedHeap::wait_while_free_regions_coming() {
5850   // Most of the time we won't have to wait, so let's do a quick test
5851   // first before we take the lock.
5852   if (!free_regions_coming()) {
5853     return;
5854   }
5855 
5856   if (G1ConcRegionFreeingVerbose) {
5857     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5858                            "waiting for free regions");
5859   }
5860 
5861   {
5862     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5863     while (free_regions_coming()) {
5864       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5865     }
5866   }
5867 
5868   if (G1ConcRegionFreeingVerbose) {
5869     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5870                            "done waiting for free regions");
5871   }
5872 }
5873 
5874 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5875   return _allocator->is_retained_old_region(hr);
5876 }
5877 
5878 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5879   _young_list->push_region(hr);
5880 }
5881 
5882 class NoYoungRegionsClosure: public HeapRegionClosure {
5883 private:
5884   bool _success;
5885 public:
5886   NoYoungRegionsClosure() : _success(true) { }
5887   bool doHeapRegion(HeapRegion* r) {
5888     if (r->is_young()) {
5889       gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5890                              p2i(r->bottom()), p2i(r->end()));
5891       _success = false;
5892     }
5893     return false;
5894   }
5895   bool success() { return _success; }
5896 };
5897 
5898 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5899   bool ret = _young_list->check_list_empty(check_sample);
5900 
5901   if (check_heap) {
5902     NoYoungRegionsClosure closure;
5903     heap_region_iterate(&closure);
5904     ret = ret && closure.success();
5905   }
5906 
5907   return ret;
5908 }
5909 
5910 class TearDownRegionSetsClosure : public HeapRegionClosure {
5911 private:
5912   HeapRegionSet *_old_set;
5913 
5914 public:
5915   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5916 
5917   bool doHeapRegion(HeapRegion* r) {
5918     if (r->is_old()) {
5919       _old_set->remove(r);
5920     } else {
5921       // We ignore free regions, we'll empty the free list afterwards.
5922       // We ignore young regions, we'll empty the young list afterwards.
5923       // We ignore humongous regions, we're not tearing down the
5924       // humongous regions set.
5925       assert(r->is_free() || r->is_young() || r->is_humongous(),
5926              "it cannot be another type");
5927     }
5928     return false;
5929   }
5930 
5931   ~TearDownRegionSetsClosure() {
5932     assert(_old_set->is_empty(), "post-condition");
5933   }
5934 };
5935 
5936 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5937   assert_at_safepoint(true /* should_be_vm_thread */);
5938 
5939   if (!free_list_only) {
5940     TearDownRegionSetsClosure cl(&_old_set);
5941     heap_region_iterate(&cl);
5942 
5943     // Note that emptying the _young_list is postponed and instead done as
5944     // the first step when rebuilding the regions sets again. The reason for
5945     // this is that during a full GC string deduplication needs to know if
5946     // a collected region was young or old when the full GC was initiated.
5947   }
5948   _hrm.remove_all_free_regions();
5949 }
5950 
5951 void G1CollectedHeap::increase_used(size_t bytes) {
5952   _summary_bytes_used += bytes;
5953 }
5954 
5955 void G1CollectedHeap::decrease_used(size_t bytes) {
5956   assert(_summary_bytes_used >= bytes,
5957          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5958          _summary_bytes_used, bytes);
5959   _summary_bytes_used -= bytes;
5960 }
5961 
5962 void G1CollectedHeap::set_used(size_t bytes) {
5963   _summary_bytes_used = bytes;
5964 }
5965 
5966 class RebuildRegionSetsClosure : public HeapRegionClosure {
5967 private:
5968   bool            _free_list_only;
5969   HeapRegionSet*   _old_set;
5970   HeapRegionManager*   _hrm;
5971   size_t          _total_used;
5972 
5973 public:
5974   RebuildRegionSetsClosure(bool free_list_only,
5975                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5976     _free_list_only(free_list_only),
5977     _old_set(old_set), _hrm(hrm), _total_used(0) {
5978     assert(_hrm->num_free_regions() == 0, "pre-condition");
5979     if (!free_list_only) {
5980       assert(_old_set->is_empty(), "pre-condition");
5981     }
5982   }
5983 
5984   bool doHeapRegion(HeapRegion* r) {
5985     if (r->is_empty()) {
5986       // Add free regions to the free list
5987       r->set_free();
5988       r->set_allocation_context(AllocationContext::system());
5989       _hrm->insert_into_free_list(r);
5990     } else if (!_free_list_only) {
5991       assert(!r->is_young(), "we should not come across young regions");
5992 
5993       if (r->is_humongous()) {
5994         // We ignore humongous regions. We left the humongous set unchanged.
5995       } else {
5996         // Objects that were compacted would have ended up on regions
5997         // that were previously old or free.  Archive regions (which are
5998         // old) will not have been touched.
5999         assert(r->is_free() || r->is_old(), "invariant");
6000         // We now consider them old, so register as such. Leave
6001         // archive regions set that way, however, while still adding
6002         // them to the old set.
6003         if (!r->is_archive()) {
6004           r->set_old();
6005         }
6006         _old_set->add(r);
6007       }
6008       _total_used += r->used();
6009     }
6010 
6011     return false;
6012   }
6013 
6014   size_t total_used() {
6015     return _total_used;
6016   }
6017 };
6018 
6019 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6020   assert_at_safepoint(true /* should_be_vm_thread */);
6021 
6022   if (!free_list_only) {
6023     _young_list->empty_list();
6024   }
6025 
6026   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6027   heap_region_iterate(&cl);
6028 
6029   if (!free_list_only) {
6030     set_used(cl.total_used());
6031     if (_archive_allocator != NULL) {
6032       _archive_allocator->clear_used();
6033     }
6034   }
6035   assert(used_unlocked() == recalculate_used(),
6036          "inconsistent used_unlocked(), "
6037          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6038          used_unlocked(), recalculate_used());
6039 }
6040 
6041 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6042   _refine_cte_cl->set_concurrent(concurrent);
6043 }
6044 
6045 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6046   HeapRegion* hr = heap_region_containing(p);
6047   return hr->is_in(p);
6048 }
6049 
6050 // Methods for the mutator alloc region
6051 
6052 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6053                                                       bool force) {
6054   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6055   assert(!force || g1_policy()->can_expand_young_list(),
6056          "if force is true we should be able to expand the young list");
6057   bool young_list_full = g1_policy()->is_young_list_full();
6058   if (force || !young_list_full) {
6059     HeapRegion* new_alloc_region = new_region(word_size,
6060                                               false /* is_old */,
6061                                               false /* do_expand */);
6062     if (new_alloc_region != NULL) {
6063       set_region_short_lived_locked(new_alloc_region);
6064       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6065       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6066       return new_alloc_region;
6067     }
6068   }
6069   return NULL;
6070 }
6071 
6072 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6073                                                   size_t allocated_bytes) {
6074   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6075   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6076 
6077   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6078   increase_used(allocated_bytes);
6079   _hr_printer.retire(alloc_region);
6080   // We update the eden sizes here, when the region is retired,
6081   // instead of when it's allocated, since this is the point that its
6082   // used space has been recored in _summary_bytes_used.
6083   g1mm()->update_eden_size();
6084 }
6085 
6086 // Methods for the GC alloc regions
6087 
6088 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6089                                                  uint count,
6090                                                  InCSetState dest) {
6091   assert(FreeList_lock->owned_by_self(), "pre-condition");
6092 
6093   if (count < g1_policy()->max_regions(dest)) {
6094     const bool is_survivor = (dest.is_young());
6095     HeapRegion* new_alloc_region = new_region(word_size,
6096                                               !is_survivor,
6097                                               true /* do_expand */);
6098     if (new_alloc_region != NULL) {
6099       // We really only need to do this for old regions given that we
6100       // should never scan survivors. But it doesn't hurt to do it
6101       // for survivors too.
6102       new_alloc_region->record_timestamp();
6103       if (is_survivor) {
6104         new_alloc_region->set_survivor();
6105         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6106         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6107       } else {
6108         new_alloc_region->set_old();
6109         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6110         check_bitmaps("Old Region Allocation", new_alloc_region);
6111       }
6112       bool during_im = collector_state()->during_initial_mark_pause();
6113       new_alloc_region->note_start_of_copying(during_im);
6114       return new_alloc_region;
6115     }
6116   }
6117   return NULL;
6118 }
6119 
6120 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6121                                              size_t allocated_bytes,
6122                                              InCSetState dest) {
6123   bool during_im = collector_state()->during_initial_mark_pause();
6124   alloc_region->note_end_of_copying(during_im);
6125   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6126   if (dest.is_young()) {
6127     young_list()->add_survivor_region(alloc_region);
6128   } else {
6129     _old_set.add(alloc_region);
6130   }
6131   _hr_printer.retire(alloc_region);
6132 }
6133 
6134 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6135   bool expanded = false;
6136   uint index = _hrm.find_highest_free(&expanded);
6137 
6138   if (index != G1_NO_HRM_INDEX) {
6139     if (expanded) {
6140       ergo_verbose1(ErgoHeapSizing,
6141                     "attempt heap expansion",
6142                     ergo_format_reason("requested address range outside heap bounds")
6143                     ergo_format_byte("region size"),
6144                     HeapRegion::GrainWords * HeapWordSize);
6145     }
6146     _hrm.allocate_free_regions_starting_at(index, 1);
6147     return region_at(index);
6148   }
6149   return NULL;
6150 }
6151 
6152 // Heap region set verification
6153 
6154 class VerifyRegionListsClosure : public HeapRegionClosure {
6155 private:
6156   HeapRegionSet*   _old_set;
6157   HeapRegionSet*   _humongous_set;
6158   HeapRegionManager*   _hrm;
6159 
6160 public:
6161   HeapRegionSetCount _old_count;
6162   HeapRegionSetCount _humongous_count;
6163   HeapRegionSetCount _free_count;
6164 
6165   VerifyRegionListsClosure(HeapRegionSet* old_set,
6166                            HeapRegionSet* humongous_set,
6167                            HeapRegionManager* hrm) :
6168     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6169     _old_count(), _humongous_count(), _free_count(){ }
6170 
6171   bool doHeapRegion(HeapRegion* hr) {
6172     if (hr->is_young()) {
6173       // TODO
6174     } else if (hr->is_humongous()) {
6175       assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6176       _humongous_count.increment(1u, hr->capacity());
6177     } else if (hr->is_empty()) {
6178       assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6179       _free_count.increment(1u, hr->capacity());
6180     } else if (hr->is_old()) {
6181       assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6182       _old_count.increment(1u, hr->capacity());
6183     } else {
6184       // There are no other valid region types. Check for one invalid
6185       // one we can identify: pinned without old or humongous set.
6186       assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6187       ShouldNotReachHere();
6188     }
6189     return false;
6190   }
6191 
6192   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6193     guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6194     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6195               old_set->total_capacity_bytes(), _old_count.capacity());
6196 
6197     guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6198     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6199               humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6200 
6201     guarantee(free_list->num_free_regions() == _free_count.length(), "Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length());
6202     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6203               free_list->total_capacity_bytes(), _free_count.capacity());
6204   }
6205 };
6206 
6207 void G1CollectedHeap::verify_region_sets() {
6208   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6209 
6210   // First, check the explicit lists.
6211   _hrm.verify();
6212   {
6213     // Given that a concurrent operation might be adding regions to
6214     // the secondary free list we have to take the lock before
6215     // verifying it.
6216     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6217     _secondary_free_list.verify_list();
6218   }
6219 
6220   // If a concurrent region freeing operation is in progress it will
6221   // be difficult to correctly attributed any free regions we come
6222   // across to the correct free list given that they might belong to
6223   // one of several (free_list, secondary_free_list, any local lists,
6224   // etc.). So, if that's the case we will skip the rest of the
6225   // verification operation. Alternatively, waiting for the concurrent
6226   // operation to complete will have a non-trivial effect on the GC's
6227   // operation (no concurrent operation will last longer than the
6228   // interval between two calls to verification) and it might hide
6229   // any issues that we would like to catch during testing.
6230   if (free_regions_coming()) {
6231     return;
6232   }
6233 
6234   // Make sure we append the secondary_free_list on the free_list so
6235   // that all free regions we will come across can be safely
6236   // attributed to the free_list.
6237   append_secondary_free_list_if_not_empty_with_lock();
6238 
6239   // Finally, make sure that the region accounting in the lists is
6240   // consistent with what we see in the heap.
6241 
6242   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6243   heap_region_iterate(&cl);
6244   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6245 }
6246 
6247 // Optimized nmethod scanning
6248 
6249 class RegisterNMethodOopClosure: public OopClosure {
6250   G1CollectedHeap* _g1h;
6251   nmethod* _nm;
6252 
6253   template <class T> void do_oop_work(T* p) {
6254     T heap_oop = oopDesc::load_heap_oop(p);
6255     if (!oopDesc::is_null(heap_oop)) {
6256       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6257       HeapRegion* hr = _g1h->heap_region_containing(obj);
6258       assert(!hr->is_continues_humongous(),
6259              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6260              " starting at " HR_FORMAT,
6261              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6262 
6263       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6264       hr->add_strong_code_root_locked(_nm);
6265     }
6266   }
6267 
6268 public:
6269   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6270     _g1h(g1h), _nm(nm) {}
6271 
6272   void do_oop(oop* p)       { do_oop_work(p); }
6273   void do_oop(narrowOop* p) { do_oop_work(p); }
6274 };
6275 
6276 class UnregisterNMethodOopClosure: public OopClosure {
6277   G1CollectedHeap* _g1h;
6278   nmethod* _nm;
6279 
6280   template <class T> void do_oop_work(T* p) {
6281     T heap_oop = oopDesc::load_heap_oop(p);
6282     if (!oopDesc::is_null(heap_oop)) {
6283       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6284       HeapRegion* hr = _g1h->heap_region_containing(obj);
6285       assert(!hr->is_continues_humongous(),
6286              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6287              " starting at " HR_FORMAT,
6288              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6289 
6290       hr->remove_strong_code_root(_nm);
6291     }
6292   }
6293 
6294 public:
6295   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6296     _g1h(g1h), _nm(nm) {}
6297 
6298   void do_oop(oop* p)       { do_oop_work(p); }
6299   void do_oop(narrowOop* p) { do_oop_work(p); }
6300 };
6301 
6302 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6303   CollectedHeap::register_nmethod(nm);
6304 
6305   guarantee(nm != NULL, "sanity");
6306   RegisterNMethodOopClosure reg_cl(this, nm);
6307   nm->oops_do(&reg_cl);
6308 }
6309 
6310 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6311   CollectedHeap::unregister_nmethod(nm);
6312 
6313   guarantee(nm != NULL, "sanity");
6314   UnregisterNMethodOopClosure reg_cl(this, nm);
6315   nm->oops_do(&reg_cl, true);
6316 }
6317 
6318 void G1CollectedHeap::purge_code_root_memory() {
6319   double purge_start = os::elapsedTime();
6320   G1CodeRootSet::purge();
6321   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6322   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6323 }
6324 
6325 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6326   G1CollectedHeap* _g1h;
6327 
6328 public:
6329   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6330     _g1h(g1h) {}
6331 
6332   void do_code_blob(CodeBlob* cb) {
6333     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6334     if (nm == NULL) {
6335       return;
6336     }
6337 
6338     if (ScavengeRootsInCode) {
6339       _g1h->register_nmethod(nm);
6340     }
6341   }
6342 };
6343 
6344 void G1CollectedHeap::rebuild_strong_code_roots() {
6345   RebuildStrongCodeRootClosure blob_cl(this);
6346   CodeCache::blobs_do(&blob_cl);
6347 }
--- EOF ---