rev 9431 : dihop-changes
rev 9433 : imported patch erik-jmasa-review
rev 9435 : [mq]: mikael-erik-review

   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 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
 406   assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);  
 407   return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
 408 }
 409 
 410 // If could fit into free regions w/o expansion, try.
 411 // Otherwise, if can expand, do so.
 412 // Otherwise, if using ex regions might help, try with ex given back.
 413 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 414   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 415 
 416   verify_region_sets_optional();
 417 
 418   uint first = G1_NO_HRM_INDEX;
 419   uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
 420 
 421   if (obj_regions == 1) {
 422     // Only one region to allocate, try to use a fast path by directly allocating
 423     // from the free lists. Do not try to expand here, we will potentially do that
 424     // later.
 425     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 426     if (hr != NULL) {
 427       first = hr->hrm_index();
 428     }
 429   } else {
 430     // We can't allocate humongous regions spanning more than one region while
 431     // cleanupComplete() is running, since some of the regions we find to be
 432     // empty might not yet be added to the free list. It is not straightforward
 433     // to know in which list they are on so that we can remove them. We only
 434     // need to do this if we need to allocate more than one region to satisfy the
 435     // current humongous allocation request. If we are only allocating one region
 436     // we use the one-region region allocation code (see above), that already
 437     // potentially waits for regions from the secondary free list.
 438     wait_while_free_regions_coming();
 439     append_secondary_free_list_if_not_empty_with_lock();
 440 
 441     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 442     // are lucky enough to find some.
 443     first = _hrm.find_contiguous_only_empty(obj_regions);
 444     if (first != G1_NO_HRM_INDEX) {
 445       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 446     }
 447   }
 448 
 449   if (first == G1_NO_HRM_INDEX) {
 450     // Policy: We could not find enough regions for the humongous object in the
 451     // free list. Look through the heap to find a mix of free and uncommitted regions.
 452     // If so, try expansion.
 453     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 454     if (first != G1_NO_HRM_INDEX) {
 455       // We found something. Make sure these regions are committed, i.e. expand
 456       // the heap. Alternatively we could do a defragmentation GC.
 457       ergo_verbose1(ErgoHeapSizing,
 458                     "attempt heap expansion",
 459                     ergo_format_reason("humongous allocation request failed")
 460                     ergo_format_byte("allocation request"),
 461                     word_size * HeapWordSize);
 462 
 463       _hrm.expand_at(first, obj_regions);
 464       g1_policy()->record_new_heap_size(num_regions());
 465 
 466 #ifdef ASSERT
 467       for (uint i = first; i < first + obj_regions; ++i) {
 468         HeapRegion* hr = region_at(i);
 469         assert(hr->is_free(), "sanity");
 470         assert(hr->is_empty(), "sanity");
 471         assert(is_on_master_free_list(hr), "sanity");
 472       }
 473 #endif
 474       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 475     } else {
 476       // Policy: Potentially trigger a defragmentation GC.
 477     }
 478   }
 479 
 480   HeapWord* result = NULL;
 481   if (first != G1_NO_HRM_INDEX) {
 482     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 483                                                        word_size, context);
 484     assert(result != NULL, "it should always return a valid result");
 485 
 486     // A successful humongous object allocation changes the used space
 487     // information of the old generation so we need to recalculate the
 488     // sizes and update the jstat counters here.
 489     g1mm()->update_sizes();
 490   }
 491 
 492   verify_region_sets_optional();
 493 
 494   return result;
 495 }
 496 
 497 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 498   assert_heap_not_locked_and_not_at_safepoint();
 499   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 500 
 501   uint dummy_gc_count_before;
 502   uint dummy_gclocker_retry_count = 0;
 503   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 504 }
 505 
 506 HeapWord*
 507 G1CollectedHeap::mem_allocate(size_t word_size,
 508                               bool*  gc_overhead_limit_was_exceeded) {
 509   assert_heap_not_locked_and_not_at_safepoint();
 510 
 511   // Loop until the allocation is satisfied, or unsatisfied after GC.
 512   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 513     uint gc_count_before;
 514 
 515     HeapWord* result = NULL;
 516     if (!is_humongous(word_size)) {
 517       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 518     } else {
 519       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 520     }
 521     if (result != NULL) {
 522       return result;
 523     }
 524 
 525     // Create the garbage collection operation...
 526     VM_G1CollectForAllocation op(gc_count_before, word_size);
 527     op.set_allocation_context(AllocationContext::current());
 528 
 529     // ...and get the VM thread to execute it.
 530     VMThread::execute(&op);
 531 
 532     if (op.prologue_succeeded() && op.pause_succeeded()) {
 533       // If the operation was successful we'll return the result even
 534       // if it is NULL. If the allocation attempt failed immediately
 535       // after a Full GC, it's unlikely we'll be able to allocate now.
 536       HeapWord* result = op.result();
 537       if (result != NULL && !is_humongous(word_size)) {
 538         // Allocations that take place on VM operations do not do any
 539         // card dirtying and we have to do it here. We only have to do
 540         // this for non-humongous allocations, though.
 541         dirty_young_block(result, word_size);
 542       }
 543       return result;
 544     } else {
 545       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 546         return NULL;
 547       }
 548       assert(op.result() == NULL,
 549              "the result should be NULL if the VM op did not succeed");
 550     }
 551 
 552     // Give a warning if we seem to be looping forever.
 553     if ((QueuedAllocationWarningCount > 0) &&
 554         (try_count % QueuedAllocationWarningCount == 0)) {
 555       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 556     }
 557   }
 558 
 559   ShouldNotReachHere();
 560   return NULL;
 561 }
 562 
 563 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 564                                                    AllocationContext_t context,
 565                                                    uint* gc_count_before_ret,
 566                                                    uint* gclocker_retry_count_ret) {
 567   // Make sure you read the note in attempt_allocation_humongous().
 568 
 569   assert_heap_not_locked_and_not_at_safepoint();
 570   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 571          "be called for humongous allocation requests");
 572 
 573   // We should only get here after the first-level allocation attempt
 574   // (attempt_allocation()) failed to allocate.
 575 
 576   // We will loop until a) we manage to successfully perform the
 577   // allocation or b) we successfully schedule a collection which
 578   // fails to perform the allocation. b) is the only case when we'll
 579   // return NULL.
 580   HeapWord* result = NULL;
 581   for (int try_count = 1; /* we'll return */; try_count += 1) {
 582     bool should_try_gc;
 583     uint gc_count_before;
 584 
 585     {
 586       MutexLockerEx x(Heap_lock);
 587       result = _allocator->attempt_allocation_locked(word_size, context);
 588       if (result != NULL) {
 589         return result;
 590       }
 591 
 592       if (GC_locker::is_active_and_needs_gc()) {
 593         if (g1_policy()->can_expand_young_list()) {
 594           // No need for an ergo verbose message here,
 595           // can_expand_young_list() does this when it returns true.
 596           result = _allocator->attempt_allocation_force(word_size, context);
 597           if (result != NULL) {
 598             return result;
 599           }
 600         }
 601         should_try_gc = false;
 602       } else {
 603         // The GCLocker may not be active but the GCLocker initiated
 604         // GC may not yet have been performed (GCLocker::needs_gc()
 605         // returns true). In this case we do not try this GC and
 606         // wait until the GCLocker initiated GC is performed, and
 607         // then retry the allocation.
 608         if (GC_locker::needs_gc()) {
 609           should_try_gc = false;
 610         } else {
 611           // Read the GC count while still holding the Heap_lock.
 612           gc_count_before = total_collections();
 613           should_try_gc = true;
 614         }
 615       }
 616     }
 617 
 618     if (should_try_gc) {
 619       bool succeeded;
 620       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 621                                    GCCause::_g1_inc_collection_pause);
 622       if (result != NULL) {
 623         assert(succeeded, "only way to get back a non-NULL result");
 624         return result;
 625       }
 626 
 627       if (succeeded) {
 628         // If we get here we successfully scheduled a collection which
 629         // failed to allocate. No point in trying to allocate
 630         // further. We'll just return NULL.
 631         MutexLockerEx x(Heap_lock);
 632         *gc_count_before_ret = total_collections();
 633         return NULL;
 634       }
 635     } else {
 636       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 637         MutexLockerEx x(Heap_lock);
 638         *gc_count_before_ret = total_collections();
 639         return NULL;
 640       }
 641       // The GCLocker is either active or the GCLocker initiated
 642       // GC has not yet been performed. Stall until it is and
 643       // then retry the allocation.
 644       GC_locker::stall_until_clear();
 645       (*gclocker_retry_count_ret) += 1;
 646     }
 647 
 648     // We can reach here if we were unsuccessful in scheduling a
 649     // collection (because another thread beat us to it) or if we were
 650     // stalled due to the GC locker. In either can we should retry the
 651     // allocation attempt in case another thread successfully
 652     // performed a collection and reclaimed enough space. We do the
 653     // first attempt (without holding the Heap_lock) here and the
 654     // follow-on attempt will be at the start of the next loop
 655     // iteration (after taking the Heap_lock).
 656     result = _allocator->attempt_allocation(word_size, context);
 657     if (result != NULL) {
 658       return result;
 659     }
 660 
 661     // Give a warning if we seem to be looping forever.
 662     if ((QueuedAllocationWarningCount > 0) &&
 663         (try_count % QueuedAllocationWarningCount == 0)) {
 664       warning("G1CollectedHeap::attempt_allocation_slow() "
 665               "retries %d times", try_count);
 666     }
 667   }
 668 
 669   ShouldNotReachHere();
 670   return NULL;
 671 }
 672 
 673 void G1CollectedHeap::begin_archive_alloc_range() {
 674   assert_at_safepoint(true /* should_be_vm_thread */);
 675   if (_archive_allocator == NULL) {
 676     _archive_allocator = G1ArchiveAllocator::create_allocator(this);
 677   }
 678 }
 679 
 680 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 681   // Allocations in archive regions cannot be of a size that would be considered
 682   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 683   // may be different at archive-restore time.
 684   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 685 }
 686 
 687 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 688   assert_at_safepoint(true /* should_be_vm_thread */);
 689   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 690   if (is_archive_alloc_too_large(word_size)) {
 691     return NULL;
 692   }
 693   return _archive_allocator->archive_mem_allocate(word_size);
 694 }
 695 
 696 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 697                                               size_t end_alignment_in_bytes) {
 698   assert_at_safepoint(true /* should_be_vm_thread */);
 699   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 700 
 701   // Call complete_archive to do the real work, filling in the MemRegion
 702   // array with the archive regions.
 703   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 704   delete _archive_allocator;
 705   _archive_allocator = NULL;
 706 }
 707 
 708 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 709   assert(ranges != NULL, "MemRegion array NULL");
 710   assert(count != 0, "No MemRegions provided");
 711   MemRegion reserved = _hrm.reserved();
 712   for (size_t i = 0; i < count; i++) {
 713     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 714       return false;
 715     }
 716   }
 717   return true;
 718 }
 719 
 720 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
 721   assert(!is_init_completed(), "Expect to be called at JVM init time");
 722   assert(ranges != NULL, "MemRegion array NULL");
 723   assert(count != 0, "No MemRegions provided");
 724   MutexLockerEx x(Heap_lock);
 725 
 726   MemRegion reserved = _hrm.reserved();
 727   HeapWord* prev_last_addr = NULL;
 728   HeapRegion* prev_last_region = NULL;
 729 
 730   // Temporarily disable pretouching of heap pages. This interface is used
 731   // when mmap'ing archived heap data in, so pre-touching is wasted.
 732   FlagSetting fs(AlwaysPreTouch, false);
 733 
 734   // Enable archive object checking in G1MarkSweep. We have to let it know
 735   // about each archive range, so that objects in those ranges aren't marked.
 736   G1MarkSweep::enable_archive_object_check();
 737 
 738   // For each specified MemRegion range, allocate the corresponding G1
 739   // regions and mark them as archive regions. We expect the ranges in
 740   // ascending starting address order, without overlap.
 741   for (size_t i = 0; i < count; i++) {
 742     MemRegion curr_range = ranges[i];
 743     HeapWord* start_address = curr_range.start();
 744     size_t word_size = curr_range.word_size();
 745     HeapWord* last_address = curr_range.last();
 746     size_t commits = 0;
 747 
 748     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 749               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 750               p2i(start_address), p2i(last_address));
 751     guarantee(start_address > prev_last_addr,
 752               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 753               p2i(start_address), p2i(prev_last_addr));
 754     prev_last_addr = last_address;
 755 
 756     // Check for ranges that start in the same G1 region in which the previous
 757     // range ended, and adjust the start address so we don't try to allocate
 758     // the same region again. If the current range is entirely within that
 759     // region, skip it, just adjusting the recorded top.
 760     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 761     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 762       start_address = start_region->end();
 763       if (start_address > last_address) {
 764         increase_used(word_size * HeapWordSize);
 765         start_region->set_top(last_address + 1);
 766         continue;
 767       }
 768       start_region->set_top(start_address);
 769       curr_range = MemRegion(start_address, last_address + 1);
 770       start_region = _hrm.addr_to_region(start_address);
 771     }
 772 
 773     // Perform the actual region allocation, exiting if it fails.
 774     // Then note how much new space we have allocated.
 775     if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
 776       return false;
 777     }
 778     increase_used(word_size * HeapWordSize);
 779     if (commits != 0) {
 780       ergo_verbose1(ErgoHeapSizing,
 781                     "attempt heap expansion",
 782                     ergo_format_reason("allocate archive regions")
 783                     ergo_format_byte("total size"),
 784                     HeapRegion::GrainWords * HeapWordSize * commits);
 785     }
 786 
 787     // Mark each G1 region touched by the range as archive, add it to the old set,
 788     // and set the allocation context and top.
 789     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 790     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 791     prev_last_region = last_region;
 792 
 793     while (curr_region != NULL) {
 794       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 795              "Region already in use (index %u)", curr_region->hrm_index());
 796       _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
 797       curr_region->set_allocation_context(AllocationContext::system());
 798       curr_region->set_archive();
 799       _old_set.add(curr_region);
 800       if (curr_region != last_region) {
 801         curr_region->set_top(curr_region->end());
 802         curr_region = _hrm.next_region_in_heap(curr_region);
 803       } else {
 804         curr_region->set_top(last_address + 1);
 805         curr_region = NULL;
 806       }
 807     }
 808 
 809     // Notify mark-sweep of the archive range.
 810     G1MarkSweep::set_range_archive(curr_range, true);
 811   }
 812   return true;
 813 }
 814 
 815 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 816   assert(!is_init_completed(), "Expect to be called at JVM init time");
 817   assert(ranges != NULL, "MemRegion array NULL");
 818   assert(count != 0, "No MemRegions provided");
 819   MemRegion reserved = _hrm.reserved();
 820   HeapWord *prev_last_addr = NULL;
 821   HeapRegion* prev_last_region = NULL;
 822 
 823   // For each MemRegion, create filler objects, if needed, in the G1 regions
 824   // that contain the address range. The address range actually within the
 825   // MemRegion will not be modified. That is assumed to have been initialized
 826   // elsewhere, probably via an mmap of archived heap data.
 827   MutexLockerEx x(Heap_lock);
 828   for (size_t i = 0; i < count; i++) {
 829     HeapWord* start_address = ranges[i].start();
 830     HeapWord* last_address = ranges[i].last();
 831 
 832     assert(reserved.contains(start_address) && reserved.contains(last_address),
 833            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 834            p2i(start_address), p2i(last_address));
 835     assert(start_address > prev_last_addr,
 836            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 837            p2i(start_address), p2i(prev_last_addr));
 838 
 839     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 840     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 841     HeapWord* bottom_address = start_region->bottom();
 842 
 843     // Check for a range beginning in the same region in which the
 844     // previous one ended.
 845     if (start_region == prev_last_region) {
 846       bottom_address = prev_last_addr + 1;
 847     }
 848 
 849     // Verify that the regions were all marked as archive regions by
 850     // alloc_archive_regions.
 851     HeapRegion* curr_region = start_region;
 852     while (curr_region != NULL) {
 853       guarantee(curr_region->is_archive(),
 854                 "Expected archive region at index %u", curr_region->hrm_index());
 855       if (curr_region != last_region) {
 856         curr_region = _hrm.next_region_in_heap(curr_region);
 857       } else {
 858         curr_region = NULL;
 859       }
 860     }
 861 
 862     prev_last_addr = last_address;
 863     prev_last_region = last_region;
 864 
 865     // Fill the memory below the allocated range with dummy object(s),
 866     // if the region bottom does not match the range start, or if the previous
 867     // range ended within the same G1 region, and there is a gap.
 868     if (start_address != bottom_address) {
 869       size_t fill_size = pointer_delta(start_address, bottom_address);
 870       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 871       increase_used(fill_size * HeapWordSize);
 872     }
 873   }
 874 }
 875 
 876 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
 877                                                      uint* gc_count_before_ret,
 878                                                      uint* gclocker_retry_count_ret) {
 879   assert_heap_not_locked_and_not_at_safepoint();
 880   assert(!is_humongous(word_size), "attempt_allocation() should not "
 881          "be called for humongous allocation requests");
 882 
 883   AllocationContext_t context = AllocationContext::current();
 884   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 885 
 886   if (result == NULL) {
 887     result = attempt_allocation_slow(word_size,
 888                                      context,
 889                                      gc_count_before_ret,
 890                                      gclocker_retry_count_ret);
 891   }
 892   assert_heap_not_locked();
 893   if (result != NULL) {
 894     dirty_young_block(result, word_size);
 895   }
 896   return result;
 897 }
 898 
 899 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 900   assert(!is_init_completed(), "Expect to be called at JVM init time");
 901   assert(ranges != NULL, "MemRegion array NULL");
 902   assert(count != 0, "No MemRegions provided");
 903   MemRegion reserved = _hrm.reserved();
 904   HeapWord* prev_last_addr = NULL;
 905   HeapRegion* prev_last_region = NULL;
 906   size_t size_used = 0;
 907   size_t uncommitted_regions = 0;
 908 
 909   // For each Memregion, free the G1 regions that constitute it, and
 910   // notify mark-sweep that the range is no longer to be considered 'archive.'
 911   MutexLockerEx x(Heap_lock);
 912   for (size_t i = 0; i < count; i++) {
 913     HeapWord* start_address = ranges[i].start();
 914     HeapWord* last_address = ranges[i].last();
 915 
 916     assert(reserved.contains(start_address) && reserved.contains(last_address),
 917            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 918            p2i(start_address), p2i(last_address));
 919     assert(start_address > prev_last_addr,
 920            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 921            p2i(start_address), p2i(prev_last_addr));
 922     size_used += ranges[i].byte_size();
 923     prev_last_addr = last_address;
 924 
 925     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 926     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 927 
 928     // Check for ranges that start in the same G1 region in which the previous
 929     // range ended, and adjust the start address so we don't try to free
 930     // the same region again. If the current range is entirely within that
 931     // region, skip it.
 932     if (start_region == prev_last_region) {
 933       start_address = start_region->end();
 934       if (start_address > last_address) {
 935         continue;
 936       }
 937       start_region = _hrm.addr_to_region(start_address);
 938     }
 939     prev_last_region = last_region;
 940 
 941     // After verifying that each region was marked as an archive region by
 942     // alloc_archive_regions, set it free and empty and uncommit it.
 943     HeapRegion* curr_region = start_region;
 944     while (curr_region != NULL) {
 945       guarantee(curr_region->is_archive(),
 946                 "Expected archive region at index %u", curr_region->hrm_index());
 947       uint curr_index = curr_region->hrm_index();
 948       _old_set.remove(curr_region);
 949       curr_region->set_free();
 950       curr_region->set_top(curr_region->bottom());
 951       if (curr_region != last_region) {
 952         curr_region = _hrm.next_region_in_heap(curr_region);
 953       } else {
 954         curr_region = NULL;
 955       }
 956       _hrm.shrink_at(curr_index, 1);
 957       uncommitted_regions++;
 958     }
 959 
 960     // Notify mark-sweep that this is no longer an archive range.
 961     G1MarkSweep::set_range_archive(ranges[i], false);
 962   }
 963 
 964   if (uncommitted_regions != 0) {
 965     ergo_verbose1(ErgoHeapSizing,
 966                   "attempt heap shrinking",
 967                   ergo_format_reason("uncommitted archive regions")
 968                   ergo_format_byte("total size"),
 969                   HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 970   }
 971   decrease_used(size_used);
 972 }
 973 
 974 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 975                                                         uint* gc_count_before_ret,
 976                                                         uint* gclocker_retry_count_ret) {
 977   // The structure of this method has a lot of similarities to
 978   // attempt_allocation_slow(). The reason these two were not merged
 979   // into a single one is that such a method would require several "if
 980   // allocation is not humongous do this, otherwise do that"
 981   // conditional paths which would obscure its flow. In fact, an early
 982   // version of this code did use a unified method which was harder to
 983   // follow and, as a result, it had subtle bugs that were hard to
 984   // track down. So keeping these two methods separate allows each to
 985   // be more readable. It will be good to keep these two in sync as
 986   // much as possible.
 987 
 988   assert_heap_not_locked_and_not_at_safepoint();
 989   assert(is_humongous(word_size), "attempt_allocation_humongous() "
 990          "should only be called for humongous allocations");
 991 
 992   // Humongous objects can exhaust the heap quickly, so we should check if we
 993   // need to start a marking cycle at each humongous object allocation. We do
 994   // the check before we do the actual allocation. The reason for doing it
 995   // before the allocation is that we avoid having to keep track of the newly
 996   // allocated memory while we do a GC.
 997   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
 998                                            word_size)) {
 999     collect(GCCause::_g1_humongous_allocation);
1000   }
1001 
1002   // We will loop until a) we manage to successfully perform the
1003   // allocation or b) we successfully schedule a collection which
1004   // fails to perform the allocation. b) is the only case when we'll
1005   // return NULL.
1006   HeapWord* result = NULL;
1007   for (int try_count = 1; /* we'll return */; try_count += 1) {
1008     bool should_try_gc;
1009     uint gc_count_before;
1010 
1011     {
1012       MutexLockerEx x(Heap_lock);
1013 
1014       // Given that humongous objects are not allocated in young
1015       // regions, we'll first try to do the allocation without doing a
1016       // collection hoping that there's enough space in the heap.
1017       result = humongous_obj_allocate(word_size, AllocationContext::current());
1018       if (result != NULL) {
1019         g1_policy()->add_last_old_allocated_bytes(humongous_obj_size_in_regions(word_size) * HeapRegion::GrainBytes);

1020         return result;
1021       }
1022 
1023       if (GC_locker::is_active_and_needs_gc()) {
1024         should_try_gc = false;
1025       } else {
1026          // The GCLocker may not be active but the GCLocker initiated
1027         // GC may not yet have been performed (GCLocker::needs_gc()
1028         // returns true). In this case we do not try this GC and
1029         // wait until the GCLocker initiated GC is performed, and
1030         // then retry the allocation.
1031         if (GC_locker::needs_gc()) {
1032           should_try_gc = false;
1033         } else {
1034           // Read the GC count while still holding the Heap_lock.
1035           gc_count_before = total_collections();
1036           should_try_gc = true;
1037         }
1038       }
1039     }
1040 
1041     if (should_try_gc) {
1042       // If we failed to allocate the humongous object, we should try to
1043       // do a collection pause (if we're allowed) in case it reclaims
1044       // enough space for the allocation to succeed after the pause.
1045 
1046       bool succeeded;
1047       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1048                                    GCCause::_g1_humongous_allocation);
1049       if (result != NULL) {
1050         assert(succeeded, "only way to get back a non-NULL result");
1051         return result;
1052       }
1053 
1054       if (succeeded) {
1055         // If we get here we successfully scheduled a collection which
1056         // failed to allocate. No point in trying to allocate
1057         // further. We'll just return NULL.
1058         MutexLockerEx x(Heap_lock);
1059         *gc_count_before_ret = total_collections();
1060         return NULL;
1061       }
1062     } else {
1063       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1064         MutexLockerEx x(Heap_lock);
1065         *gc_count_before_ret = total_collections();
1066         return NULL;
1067       }
1068       // The GCLocker is either active or the GCLocker initiated
1069       // GC has not yet been performed. Stall until it is and
1070       // then retry the allocation.
1071       GC_locker::stall_until_clear();
1072       (*gclocker_retry_count_ret) += 1;
1073     }
1074 
1075     // We can reach here if we were unsuccessful in scheduling a
1076     // collection (because another thread beat us to it) or if we were
1077     // stalled due to the GC locker. In either can we should retry the
1078     // allocation attempt in case another thread successfully
1079     // performed a collection and reclaimed enough space.  Give a
1080     // warning if we seem to be looping forever.
1081 
1082     if ((QueuedAllocationWarningCount > 0) &&
1083         (try_count % QueuedAllocationWarningCount == 0)) {
1084       warning("G1CollectedHeap::attempt_allocation_humongous() "
1085               "retries %d times", try_count);
1086     }
1087   }
1088 
1089   ShouldNotReachHere();
1090   return NULL;
1091 }
1092 
1093 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1094                                                            AllocationContext_t context,
1095                                                            bool expect_null_mutator_alloc_region) {
1096   assert_at_safepoint(true /* should_be_vm_thread */);
1097   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1098          "the current alloc region was unexpectedly found to be non-NULL");
1099 
1100   if (!is_humongous(word_size)) {
1101     return _allocator->attempt_allocation_locked(word_size, context);
1102   } else {
1103     HeapWord* result = humongous_obj_allocate(word_size, context);
1104     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1105       collector_state()->set_initiate_conc_mark_if_possible(true);
1106     }
1107     return result;
1108   }
1109 
1110   ShouldNotReachHere();
1111 }
1112 
1113 class PostMCRemSetClearClosure: public HeapRegionClosure {
1114   G1CollectedHeap* _g1h;
1115   ModRefBarrierSet* _mr_bs;
1116 public:
1117   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1118     _g1h(g1h), _mr_bs(mr_bs) {}
1119 
1120   bool doHeapRegion(HeapRegion* r) {
1121     HeapRegionRemSet* hrrs = r->rem_set();
1122 
1123     _g1h->reset_gc_time_stamps(r);
1124 
1125     if (r->is_continues_humongous()) {
1126       // We'll assert that the strong code root list and RSet is empty
1127       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1128       assert(hrrs->occupied() == 0, "RSet should be empty");
1129     } else {
1130       hrrs->clear();
1131     }
1132     // You might think here that we could clear just the cards
1133     // corresponding to the used region.  But no: if we leave a dirty card
1134     // in a region we might allocate into, then it would prevent that card
1135     // from being enqueued, and cause it to be missed.
1136     // Re: the performance cost: we shouldn't be doing full GC anyway!
1137     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1138 
1139     return false;
1140   }
1141 };
1142 
1143 void G1CollectedHeap::clear_rsets_post_compaction() {
1144   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1145   heap_region_iterate(&rs_clear);
1146 }
1147 
1148 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1149   G1CollectedHeap*   _g1h;
1150   UpdateRSOopClosure _cl;
1151 public:
1152   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1153     _cl(g1->g1_rem_set(), worker_i),
1154     _g1h(g1)
1155   { }
1156 
1157   bool doHeapRegion(HeapRegion* r) {
1158     if (!r->is_continues_humongous()) {
1159       _cl.set_from(r);
1160       r->oop_iterate(&_cl);
1161     }
1162     return false;
1163   }
1164 };
1165 
1166 class ParRebuildRSTask: public AbstractGangTask {
1167   G1CollectedHeap* _g1;
1168   HeapRegionClaimer _hrclaimer;
1169 
1170 public:
1171   ParRebuildRSTask(G1CollectedHeap* g1) :
1172       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1173 
1174   void work(uint worker_id) {
1175     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1176     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1177   }
1178 };
1179 
1180 class PostCompactionPrinterClosure: public HeapRegionClosure {
1181 private:
1182   G1HRPrinter* _hr_printer;
1183 public:
1184   bool doHeapRegion(HeapRegion* hr) {
1185     assert(!hr->is_young(), "not expecting to find young regions");
1186     if (hr->is_free()) {
1187       // We only generate output for non-empty regions.
1188     } else if (hr->is_starts_humongous()) {
1189       _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1190     } else if (hr->is_continues_humongous()) {
1191       _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1192     } else if (hr->is_archive()) {
1193       _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1194     } else if (hr->is_old()) {
1195       _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1196     } else {
1197       ShouldNotReachHere();
1198     }
1199     return false;
1200   }
1201 
1202   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1203     : _hr_printer(hr_printer) { }
1204 };
1205 
1206 void G1CollectedHeap::print_hrm_post_compaction() {
1207   PostCompactionPrinterClosure cl(hr_printer());
1208   heap_region_iterate(&cl);
1209 }
1210 
1211 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1212                                          bool clear_all_soft_refs) {
1213   assert_at_safepoint(true /* should_be_vm_thread */);
1214 
1215   if (GC_locker::check_active_before_gc()) {
1216     return false;
1217   }
1218 
1219   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1220   gc_timer->register_gc_start();
1221 
1222   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1223   GCIdMark gc_id_mark;
1224   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1225 
1226   SvcGCMarker sgcm(SvcGCMarker::FULL);
1227   ResourceMark rm;
1228 
1229   G1Log::update_level();
1230   print_heap_before_gc();
1231   trace_heap_before_gc(gc_tracer);
1232 
1233   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1234 
1235   verify_region_sets_optional();
1236 
1237   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1238                            collector_policy()->should_clear_all_soft_refs();
1239 
1240   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1241 
1242   {
1243     IsGCActiveMark x;
1244 
1245     // Timing
1246     assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1247     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1248 
1249     {
1250       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1251       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1252       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1253 
1254       g1_policy()->record_full_collection_start();
1255 
1256       // Note: When we have a more flexible GC logging framework that
1257       // allows us to add optional attributes to a GC log record we
1258       // could consider timing and reporting how long we wait in the
1259       // following two methods.
1260       wait_while_free_regions_coming();
1261       // If we start the compaction before the CM threads finish
1262       // scanning the root regions we might trip them over as we'll
1263       // be moving objects / updating references. So let's wait until
1264       // they are done. By telling them to abort, they should complete
1265       // early.
1266       _cm->root_regions()->abort();
1267       _cm->root_regions()->wait_until_scan_finished();
1268       append_secondary_free_list_if_not_empty_with_lock();
1269 
1270       gc_prologue(true);
1271       increment_total_collections(true /* full gc */);
1272       increment_old_marking_cycles_started();
1273 
1274       assert(used() == recalculate_used(), "Should be equal");
1275 
1276       verify_before_gc();
1277 
1278       check_bitmaps("Full GC Start");
1279       pre_full_gc_dump(gc_timer);
1280 
1281 #if defined(COMPILER2) || INCLUDE_JVMCI
1282       DerivedPointerTable::clear();
1283 #endif
1284 
1285       // Disable discovery and empty the discovered lists
1286       // for the CM ref processor.
1287       ref_processor_cm()->disable_discovery();
1288       ref_processor_cm()->abandon_partial_discovery();
1289       ref_processor_cm()->verify_no_references_recorded();
1290 
1291       // Abandon current iterations of concurrent marking and concurrent
1292       // refinement, if any are in progress. We have to do this before
1293       // wait_until_scan_finished() below.
1294       concurrent_mark()->abort();
1295 
1296       // Make sure we'll choose a new allocation region afterwards.
1297       _allocator->release_mutator_alloc_region();
1298       _allocator->abandon_gc_alloc_regions();
1299       g1_rem_set()->cleanupHRRS();
1300 
1301       // We should call this after we retire any currently active alloc
1302       // regions so that all the ALLOC / RETIRE events are generated
1303       // before the start GC event.
1304       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1305 
1306       // We may have added regions to the current incremental collection
1307       // set between the last GC or pause and now. We need to clear the
1308       // incremental collection set and then start rebuilding it afresh
1309       // after this full GC.
1310       abandon_collection_set(g1_policy()->inc_cset_head());
1311       g1_policy()->clear_incremental_cset();
1312       g1_policy()->stop_incremental_cset_building();
1313 
1314       tear_down_region_sets(false /* free_list_only */);
1315       collector_state()->set_gcs_are_young(true);
1316 
1317       // See the comments in g1CollectedHeap.hpp and
1318       // G1CollectedHeap::ref_processing_init() about
1319       // how reference processing currently works in G1.
1320 
1321       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1322       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1323 
1324       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1325       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1326 
1327       ref_processor_stw()->enable_discovery();
1328       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1329 
1330       // Do collection work
1331       {
1332         HandleMark hm;  // Discard invalid handles created during gc
1333         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1334       }
1335 
1336       assert(num_free_regions() == 0, "we should not have added any free regions");
1337       rebuild_region_sets(false /* free_list_only */);
1338 
1339       // Enqueue any discovered reference objects that have
1340       // not been removed from the discovered lists.
1341       ref_processor_stw()->enqueue_discovered_references();
1342 
1343 #if defined(COMPILER2) || INCLUDE_JVMCI
1344       DerivedPointerTable::update_pointers();
1345 #endif
1346 
1347       MemoryService::track_memory_usage();
1348 
1349       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1350       ref_processor_stw()->verify_no_references_recorded();
1351 
1352       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1353       ClassLoaderDataGraph::purge();
1354       MetaspaceAux::verify_metrics();
1355 
1356       // Note: since we've just done a full GC, concurrent
1357       // marking is no longer active. Therefore we need not
1358       // re-enable reference discovery for the CM ref processor.
1359       // That will be done at the start of the next marking cycle.
1360       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1361       ref_processor_cm()->verify_no_references_recorded();
1362 
1363       reset_gc_time_stamp();
1364       // Since everything potentially moved, we will clear all remembered
1365       // sets, and clear all cards.  Later we will rebuild remembered
1366       // sets. We will also reset the GC time stamps of the regions.
1367       clear_rsets_post_compaction();
1368       check_gc_time_stamps();
1369 
1370       resize_if_necessary_after_full_collection();
1371 
1372       if (_hr_printer.is_active()) {
1373         // We should do this after we potentially resize the heap so
1374         // that all the COMMIT / UNCOMMIT events are generated before
1375         // the end GC event.
1376 
1377         print_hrm_post_compaction();
1378         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1379       }
1380 
1381       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1382       if (hot_card_cache->use_cache()) {
1383         hot_card_cache->reset_card_counts();
1384         hot_card_cache->reset_hot_cache();
1385       }
1386 
1387       // Rebuild remembered sets of all regions.
1388       uint n_workers =
1389         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1390                                                 workers()->active_workers(),
1391                                                 Threads::number_of_non_daemon_threads());
1392       workers()->set_active_workers(n_workers);
1393 
1394       ParRebuildRSTask rebuild_rs_task(this);
1395       workers()->run_task(&rebuild_rs_task);
1396 
1397       // Rebuild the strong code root lists for each region
1398       rebuild_strong_code_roots();
1399 
1400       if (true) { // FIXME
1401         MetaspaceGC::compute_new_size();
1402       }
1403 
1404 #ifdef TRACESPINNING
1405       ParallelTaskTerminator::print_termination_counts();
1406 #endif
1407 
1408       // Discard all rset updates
1409       JavaThread::dirty_card_queue_set().abandon_logs();
1410       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1411 
1412       _young_list->reset_sampled_info();
1413       // At this point there should be no regions in the
1414       // entire heap tagged as young.
1415       assert(check_young_list_empty(true /* check_heap */),
1416              "young list should be empty at this point");
1417 
1418       // Update the number of full collections that have been completed.
1419       increment_old_marking_cycles_completed(false /* concurrent */);
1420 
1421       _hrm.verify_optional();
1422       verify_region_sets_optional();
1423 
1424       verify_after_gc();
1425 
1426       // Clear the previous marking bitmap, if needed for bitmap verification.
1427       // Note we cannot do this when we clear the next marking bitmap in
1428       // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1429       // objects marked during a full GC against the previous bitmap.
1430       // But we need to clear it before calling check_bitmaps below since
1431       // the full GC has compacted objects and updated TAMS but not updated
1432       // the prev bitmap.
1433       if (G1VerifyBitmaps) {
1434         ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1435       }
1436       check_bitmaps("Full GC End");
1437 
1438       // Start a new incremental collection set for the next pause
1439       assert(g1_policy()->collection_set() == NULL, "must be");
1440       g1_policy()->start_incremental_cset_building();
1441 
1442       clear_cset_fast_test();
1443 
1444       _allocator->init_mutator_alloc_region();
1445 
1446       g1_policy()->record_full_collection_end();
1447 
1448       if (G1Log::fine()) {
1449         g1_policy()->print_heap_transition();
1450       }
1451 
1452       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1453       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1454       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1455       // before any GC notifications are raised.
1456       g1mm()->update_sizes();
1457 
1458       gc_epilogue(true);
1459     }
1460 
1461     if (G1Log::finer()) {
1462       g1_policy()->print_detailed_heap_transition(true /* full */);
1463     }
1464 
1465     print_heap_after_gc();
1466     trace_heap_after_gc(gc_tracer);
1467 
1468     post_full_gc_dump(gc_timer);
1469 
1470     gc_timer->register_gc_end();
1471     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1472   }
1473 
1474   return true;
1475 }
1476 
1477 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1478   // Currently, there is no facility in the do_full_collection(bool) API to notify
1479   // the caller that the collection did not succeed (e.g., because it was locked
1480   // out by the GC locker). So, right now, we'll ignore the return value.
1481   bool dummy = do_full_collection(true,                /* explicit_gc */
1482                                   clear_all_soft_refs);
1483 }
1484 
1485 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1486   // Include bytes that will be pre-allocated to support collections, as "used".
1487   const size_t used_after_gc = used();
1488   const size_t capacity_after_gc = capacity();
1489   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1490 
1491   // This is enforced in arguments.cpp.
1492   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1493          "otherwise the code below doesn't make sense");
1494 
1495   // We don't have floating point command-line arguments
1496   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1497   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1498   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1499   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1500 
1501   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1502   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1503 
1504   // We have to be careful here as these two calculations can overflow
1505   // 32-bit size_t's.
1506   double used_after_gc_d = (double) used_after_gc;
1507   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1508   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1509 
1510   // Let's make sure that they are both under the max heap size, which
1511   // by default will make them fit into a size_t.
1512   double desired_capacity_upper_bound = (double) max_heap_size;
1513   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1514                                     desired_capacity_upper_bound);
1515   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1516                                     desired_capacity_upper_bound);
1517 
1518   // We can now safely turn them into size_t's.
1519   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1520   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1521 
1522   // This assert only makes sense here, before we adjust them
1523   // with respect to the min and max heap size.
1524   assert(minimum_desired_capacity <= maximum_desired_capacity,
1525          "minimum_desired_capacity = " SIZE_FORMAT ", "
1526          "maximum_desired_capacity = " SIZE_FORMAT,
1527          minimum_desired_capacity, maximum_desired_capacity);
1528 
1529   // Should not be greater than the heap max size. No need to adjust
1530   // it with respect to the heap min size as it's a lower bound (i.e.,
1531   // we'll try to make the capacity larger than it, not smaller).
1532   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1533   // Should not be less than the heap min size. No need to adjust it
1534   // with respect to the heap max size as it's an upper bound (i.e.,
1535   // we'll try to make the capacity smaller than it, not greater).
1536   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1537 
1538   if (capacity_after_gc < minimum_desired_capacity) {
1539     // Don't expand unless it's significant
1540     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1541     ergo_verbose4(ErgoHeapSizing,
1542                   "attempt heap expansion",
1543                   ergo_format_reason("capacity lower than "
1544                                      "min desired capacity after Full GC")
1545                   ergo_format_byte("capacity")
1546                   ergo_format_byte("occupancy")
1547                   ergo_format_byte_perc("min desired capacity"),
1548                   capacity_after_gc, used_after_gc,
1549                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1550     expand(expand_bytes);
1551 
1552     // No expansion, now see if we want to shrink
1553   } else if (capacity_after_gc > maximum_desired_capacity) {
1554     // Capacity too large, compute shrinking size
1555     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1556     ergo_verbose4(ErgoHeapSizing,
1557                   "attempt heap shrinking",
1558                   ergo_format_reason("capacity higher than "
1559                                      "max desired capacity after Full GC")
1560                   ergo_format_byte("capacity")
1561                   ergo_format_byte("occupancy")
1562                   ergo_format_byte_perc("max desired capacity"),
1563                   capacity_after_gc, used_after_gc,
1564                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1565     shrink(shrink_bytes);
1566   }
1567 }
1568 
1569 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1570                                                             AllocationContext_t context,
1571                                                             bool do_gc,
1572                                                             bool clear_all_soft_refs,
1573                                                             bool expect_null_mutator_alloc_region,
1574                                                             bool* gc_succeeded) {
1575   *gc_succeeded = true;
1576   // Let's attempt the allocation first.
1577   HeapWord* result =
1578     attempt_allocation_at_safepoint(word_size,
1579                                     context,
1580                                     expect_null_mutator_alloc_region);
1581   if (result != NULL) {
1582     assert(*gc_succeeded, "sanity");
1583     return result;
1584   }
1585 
1586   // In a G1 heap, we're supposed to keep allocation from failing by
1587   // incremental pauses.  Therefore, at least for now, we'll favor
1588   // expansion over collection.  (This might change in the future if we can
1589   // do something smarter than full collection to satisfy a failed alloc.)
1590   result = expand_and_allocate(word_size, context);
1591   if (result != NULL) {
1592     assert(*gc_succeeded, "sanity");
1593     return result;
1594   }
1595 
1596   if (do_gc) {
1597     // Expansion didn't work, we'll try to do a Full GC.
1598     *gc_succeeded = do_full_collection(false, /* explicit_gc */
1599                                        clear_all_soft_refs);
1600   }
1601 
1602   return NULL;
1603 }
1604 
1605 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1606                                                      AllocationContext_t context,
1607                                                      bool* succeeded) {
1608   assert_at_safepoint(true /* should_be_vm_thread */);
1609 
1610   // Attempts to allocate followed by Full GC.
1611   HeapWord* result =
1612     satisfy_failed_allocation_helper(word_size,
1613                                      context,
1614                                      true,  /* do_gc */
1615                                      false, /* clear_all_soft_refs */
1616                                      false, /* expect_null_mutator_alloc_region */
1617                                      succeeded);
1618 
1619   if (result != NULL || !*succeeded) {
1620     return result;
1621   }
1622 
1623   // Attempts to allocate followed by Full GC that will collect all soft references.
1624   result = satisfy_failed_allocation_helper(word_size,
1625                                             context,
1626                                             true, /* do_gc */
1627                                             true, /* clear_all_soft_refs */
1628                                             true, /* expect_null_mutator_alloc_region */
1629                                             succeeded);
1630 
1631   if (result != NULL || !*succeeded) {
1632     return result;
1633   }
1634 
1635   // Attempts to allocate, no GC
1636   result = satisfy_failed_allocation_helper(word_size,
1637                                             context,
1638                                             false, /* do_gc */
1639                                             false, /* clear_all_soft_refs */
1640                                             true,  /* expect_null_mutator_alloc_region */
1641                                             succeeded);
1642 
1643   if (result != NULL) {
1644     assert(*succeeded, "sanity");
1645     return result;
1646   }
1647 
1648   assert(!collector_policy()->should_clear_all_soft_refs(),
1649          "Flag should have been handled and cleared prior to this point");
1650 
1651   // What else?  We might try synchronous finalization later.  If the total
1652   // space available is large enough for the allocation, then a more
1653   // complete compaction phase than we've tried so far might be
1654   // appropriate.
1655   assert(*succeeded, "sanity");
1656   return NULL;
1657 }
1658 
1659 // Attempting to expand the heap sufficiently
1660 // to support an allocation of the given "word_size".  If
1661 // successful, perform the allocation and return the address of the
1662 // allocated block, or else "NULL".
1663 
1664 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1665   assert_at_safepoint(true /* should_be_vm_thread */);
1666 
1667   verify_region_sets_optional();
1668 
1669   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1670   ergo_verbose1(ErgoHeapSizing,
1671                 "attempt heap expansion",
1672                 ergo_format_reason("allocation request failed")
1673                 ergo_format_byte("allocation request"),
1674                 word_size * HeapWordSize);
1675   if (expand(expand_bytes)) {
1676     _hrm.verify_optional();
1677     verify_region_sets_optional();
1678     return attempt_allocation_at_safepoint(word_size,
1679                                            context,
1680                                            false /* expect_null_mutator_alloc_region */);
1681   }
1682   return NULL;
1683 }
1684 
1685 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1686   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1687   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1688                                        HeapRegion::GrainBytes);
1689   ergo_verbose2(ErgoHeapSizing,
1690                 "expand the heap",
1691                 ergo_format_byte("requested expansion amount")
1692                 ergo_format_byte("attempted expansion amount"),
1693                 expand_bytes, aligned_expand_bytes);
1694 
1695   if (is_maximal_no_gc()) {
1696     ergo_verbose0(ErgoHeapSizing,
1697                       "did not expand the heap",
1698                       ergo_format_reason("heap already fully expanded"));
1699     return false;
1700   }
1701 
1702   double expand_heap_start_time_sec = os::elapsedTime();
1703   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1704   assert(regions_to_expand > 0, "Must expand by at least one region");
1705 
1706   uint expanded_by = _hrm.expand_by(regions_to_expand);
1707   if (expand_time_ms != NULL) {
1708     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1709   }
1710 
1711   if (expanded_by > 0) {
1712     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1713     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1714     g1_policy()->record_new_heap_size(num_regions());
1715   } else {
1716     ergo_verbose0(ErgoHeapSizing,
1717                   "did not expand the heap",
1718                   ergo_format_reason("heap expansion operation failed"));
1719     // The expansion of the virtual storage space was unsuccessful.
1720     // Let's see if it was because we ran out of swap.
1721     if (G1ExitOnExpansionFailure &&
1722         _hrm.available() >= regions_to_expand) {
1723       // We had head room...
1724       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1725     }
1726   }
1727   return regions_to_expand > 0;
1728 }
1729 
1730 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1731   size_t aligned_shrink_bytes =
1732     ReservedSpace::page_align_size_down(shrink_bytes);
1733   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1734                                          HeapRegion::GrainBytes);
1735   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1736 
1737   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1738   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1739 
1740   ergo_verbose3(ErgoHeapSizing,
1741                 "shrink the heap",
1742                 ergo_format_byte("requested shrinking amount")
1743                 ergo_format_byte("aligned shrinking amount")
1744                 ergo_format_byte("attempted shrinking amount"),
1745                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1746   if (num_regions_removed > 0) {
1747     g1_policy()->record_new_heap_size(num_regions());
1748   } else {
1749     ergo_verbose0(ErgoHeapSizing,
1750                   "did not shrink the heap",
1751                   ergo_format_reason("heap shrinking operation failed"));
1752   }
1753 }
1754 
1755 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1756   verify_region_sets_optional();
1757 
1758   // We should only reach here at the end of a Full GC which means we
1759   // should not not be holding to any GC alloc regions. The method
1760   // below will make sure of that and do any remaining clean up.
1761   _allocator->abandon_gc_alloc_regions();
1762 
1763   // Instead of tearing down / rebuilding the free lists here, we
1764   // could instead use the remove_all_pending() method on free_list to
1765   // remove only the ones that we need to remove.
1766   tear_down_region_sets(true /* free_list_only */);
1767   shrink_helper(shrink_bytes);
1768   rebuild_region_sets(true /* free_list_only */);
1769 
1770   _hrm.verify_optional();
1771   verify_region_sets_optional();
1772 }
1773 
1774 // Public methods.
1775 
1776 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1777   CollectedHeap(),
1778   _g1_policy(policy_),
1779   _dirty_card_queue_set(false),
1780   _is_alive_closure_cm(this),
1781   _is_alive_closure_stw(this),
1782   _ref_processor_cm(NULL),
1783   _ref_processor_stw(NULL),
1784   _bot_shared(NULL),
1785   _cg1r(NULL),
1786   _g1mm(NULL),
1787   _refine_cte_cl(NULL),
1788   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1789   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1790   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1791   _humongous_reclaim_candidates(),
1792   _has_humongous_reclaim_candidates(false),
1793   _archive_allocator(NULL),
1794   _free_regions_coming(false),
1795   _young_list(new YoungList(this)),
1796   _gc_time_stamp(0),
1797   _summary_bytes_used(0),
1798   _survivor_evac_stats(YoungPLABSize, PLABWeight),
1799   _old_evac_stats(OldPLABSize, PLABWeight),
1800   _expand_heap_after_alloc_failure(true),
1801   _old_marking_cycles_started(0),
1802   _old_marking_cycles_completed(0),
1803   _heap_summary_sent(false),
1804   _in_cset_fast_test(),
1805   _dirty_cards_region_list(NULL),
1806   _worker_cset_start_region(NULL),
1807   _worker_cset_start_region_time_stamp(NULL),
1808   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1809   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1810   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1811   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1812 
1813   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1814                           /* are_GC_task_threads */true,
1815                           /* are_ConcurrentGC_threads */false);
1816   _workers->initialize_workers();
1817 
1818   _allocator = G1Allocator::create_allocator(this);
1819   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1820 
1821   // Override the default _filler_array_max_size so that no humongous filler
1822   // objects are created.
1823   _filler_array_max_size = _humongous_object_threshold_in_words;
1824 
1825   uint n_queues = ParallelGCThreads;
1826   _task_queues = new RefToScanQueueSet(n_queues);
1827 
1828   uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1829   assert(n_rem_sets > 0, "Invariant.");
1830 
1831   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1832   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1833   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1834 
1835   for (uint i = 0; i < n_queues; i++) {
1836     RefToScanQueue* q = new RefToScanQueue();
1837     q->initialize();
1838     _task_queues->register_queue(i, q);
1839     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1840   }
1841   clear_cset_start_regions();
1842 
1843   // Initialize the G1EvacuationFailureALot counters and flags.
1844   NOT_PRODUCT(reset_evacuation_should_fail();)
1845 
1846   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1847 }
1848 
1849 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1850                                                                  size_t size,
1851                                                                  size_t translation_factor) {
1852   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1853   // Allocate a new reserved space, preferring to use large pages.
1854   ReservedSpace rs(size, preferred_page_size);
1855   G1RegionToSpaceMapper* result  =
1856     G1RegionToSpaceMapper::create_mapper(rs,
1857                                          size,
1858                                          rs.alignment(),
1859                                          HeapRegion::GrainBytes,
1860                                          translation_factor,
1861                                          mtGC);
1862   if (TracePageSizes) {
1863     gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1864                            description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1865   }
1866   return result;
1867 }
1868 
1869 jint G1CollectedHeap::initialize() {
1870   CollectedHeap::pre_initialize();
1871   os::enable_vtime();
1872 
1873   G1Log::init();
1874 
1875   // Necessary to satisfy locking discipline assertions.
1876 
1877   MutexLocker x(Heap_lock);
1878 
1879   // We have to initialize the printer before committing the heap, as
1880   // it will be used then.
1881   _hr_printer.set_active(G1PrintHeapRegions);
1882 
1883   // While there are no constraints in the GC code that HeapWordSize
1884   // be any particular value, there are multiple other areas in the
1885   // system which believe this to be true (e.g. oop->object_size in some
1886   // cases incorrectly returns the size in wordSize units rather than
1887   // HeapWordSize).
1888   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1889 
1890   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1891   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1892   size_t heap_alignment = collector_policy()->heap_alignment();
1893 
1894   // Ensure that the sizes are properly aligned.
1895   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1896   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1897   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1898 
1899   _refine_cte_cl = new RefineCardTableEntryClosure();
1900 
1901   jint ecode = JNI_OK;
1902   _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1903   if (_cg1r == NULL) {
1904     return ecode;
1905   }
1906 
1907   // Reserve the maximum.
1908 
1909   // When compressed oops are enabled, the preferred heap base
1910   // is calculated by subtracting the requested size from the
1911   // 32Gb boundary and using the result as the base address for
1912   // heap reservation. If the requested size is not aligned to
1913   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1914   // into the ReservedHeapSpace constructor) then the actual
1915   // base of the reserved heap may end up differing from the
1916   // address that was requested (i.e. the preferred heap base).
1917   // If this happens then we could end up using a non-optimal
1918   // compressed oops mode.
1919 
1920   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1921                                                  heap_alignment);
1922 
1923   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1924 
1925   // Create the barrier set for the entire reserved region.
1926   G1SATBCardTableLoggingModRefBS* bs
1927     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1928   bs->initialize();
1929   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1930   set_barrier_set(bs);
1931 
1932   // Also create a G1 rem set.
1933   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1934 
1935   // Carve out the G1 part of the heap.
1936 
1937   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1938   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1939   G1RegionToSpaceMapper* heap_storage =
1940     G1RegionToSpaceMapper::create_mapper(g1_rs,
1941                                          g1_rs.size(),
1942                                          page_size,
1943                                          HeapRegion::GrainBytes,
1944                                          1,
1945                                          mtJavaHeap);
1946   os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1947                        max_byte_size, page_size,
1948                        heap_rs.base(),
1949                        heap_rs.size());
1950   heap_storage->set_mapping_changed_listener(&_listener);
1951 
1952   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1953   G1RegionToSpaceMapper* bot_storage =
1954     create_aux_memory_mapper("Block offset table",
1955                              G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1956                              G1BlockOffsetSharedArray::heap_map_factor());
1957 
1958   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1959   G1RegionToSpaceMapper* cardtable_storage =
1960     create_aux_memory_mapper("Card table",
1961                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1962                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1963 
1964   G1RegionToSpaceMapper* card_counts_storage =
1965     create_aux_memory_mapper("Card counts table",
1966                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1967                              G1CardCounts::heap_map_factor());
1968 
1969   size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1970   G1RegionToSpaceMapper* prev_bitmap_storage =
1971     create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1972   G1RegionToSpaceMapper* next_bitmap_storage =
1973     create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1974 
1975   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1976   g1_barrier_set()->initialize(cardtable_storage);
1977    // Do later initialization work for concurrent refinement.
1978   _cg1r->init(card_counts_storage);
1979 
1980   // 6843694 - ensure that the maximum region index can fit
1981   // in the remembered set structures.
1982   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1983   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1984 
1985   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1986   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1987   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1988             "too many cards per region");
1989 
1990   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1991 
1992   _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1993 
1994   {
1995     HeapWord* start = _hrm.reserved().start();
1996     HeapWord* end = _hrm.reserved().end();
1997     size_t granularity = HeapRegion::GrainBytes;
1998 
1999     _in_cset_fast_test.initialize(start, end, granularity);
2000     _humongous_reclaim_candidates.initialize(start, end, granularity);
2001   }
2002 
2003   // Create the ConcurrentMark data structure and thread.
2004   // (Must do this late, so that "max_regions" is defined.)
2005   _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2006   if (_cm == NULL || !_cm->completed_initialization()) {
2007     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2008     return JNI_ENOMEM;
2009   }
2010   _cmThread = _cm->cmThread();
2011 
2012   // Initialize the from_card cache structure of HeapRegionRemSet.
2013   HeapRegionRemSet::init_heap(max_regions());
2014 
2015   // Now expand into the initial heap size.
2016   if (!expand(init_byte_size)) {
2017     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2018     return JNI_ENOMEM;
2019   }
2020 
2021   // Perform any initialization actions delegated to the policy.
2022   g1_policy()->init();
2023 
2024   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2025                                                SATB_Q_FL_lock,
2026                                                G1SATBProcessCompletedThreshold,
2027                                                Shared_SATB_Q_lock);
2028 
2029   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2030                                                 DirtyCardQ_CBL_mon,
2031                                                 DirtyCardQ_FL_lock,
2032                                                 concurrent_g1_refine()->yellow_zone(),
2033                                                 concurrent_g1_refine()->red_zone(),
2034                                                 Shared_DirtyCardQ_lock);
2035 
2036   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2037                                     DirtyCardQ_CBL_mon,
2038                                     DirtyCardQ_FL_lock,
2039                                     -1, // never trigger processing
2040                                     -1, // no limit on length
2041                                     Shared_DirtyCardQ_lock,
2042                                     &JavaThread::dirty_card_queue_set());
2043 
2044   // Here we allocate the dummy HeapRegion that is required by the
2045   // G1AllocRegion class.
2046   HeapRegion* dummy_region = _hrm.get_dummy_region();
2047 
2048   // We'll re-use the same region whether the alloc region will
2049   // require BOT updates or not and, if it doesn't, then a non-young
2050   // region will complain that it cannot support allocations without
2051   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2052   dummy_region->set_eden();
2053   // Make sure it's full.
2054   dummy_region->set_top(dummy_region->end());
2055   G1AllocRegion::setup(this, dummy_region);
2056 
2057   _allocator->init_mutator_alloc_region();
2058 
2059   // Do create of the monitoring and management support so that
2060   // values in the heap have been properly initialized.
2061   _g1mm = new G1MonitoringSupport(this);
2062 
2063   G1StringDedup::initialize();
2064 
2065   _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2066   for (uint i = 0; i < ParallelGCThreads; i++) {
2067     new (&_preserved_objs[i]) OopAndMarkOopStack();
2068   }
2069 
2070   return JNI_OK;
2071 }
2072 
2073 void G1CollectedHeap::stop() {
2074   // Stop all concurrent threads. We do this to make sure these threads
2075   // do not continue to execute and access resources (e.g. gclog_or_tty)
2076   // that are destroyed during shutdown.
2077   _cg1r->stop();
2078   _cmThread->stop();
2079   if (G1StringDedup::is_enabled()) {
2080     G1StringDedup::stop();
2081   }
2082 }
2083 
2084 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2085   return HeapRegion::max_region_size();
2086 }
2087 
2088 void G1CollectedHeap::post_initialize() {
2089   CollectedHeap::post_initialize();
2090   ref_processing_init();
2091 }
2092 
2093 void G1CollectedHeap::ref_processing_init() {
2094   // Reference processing in G1 currently works as follows:
2095   //
2096   // * There are two reference processor instances. One is
2097   //   used to record and process discovered references
2098   //   during concurrent marking; the other is used to
2099   //   record and process references during STW pauses
2100   //   (both full and incremental).
2101   // * Both ref processors need to 'span' the entire heap as
2102   //   the regions in the collection set may be dotted around.
2103   //
2104   // * For the concurrent marking ref processor:
2105   //   * Reference discovery is enabled at initial marking.
2106   //   * Reference discovery is disabled and the discovered
2107   //     references processed etc during remarking.
2108   //   * Reference discovery is MT (see below).
2109   //   * Reference discovery requires a barrier (see below).
2110   //   * Reference processing may or may not be MT
2111   //     (depending on the value of ParallelRefProcEnabled
2112   //     and ParallelGCThreads).
2113   //   * A full GC disables reference discovery by the CM
2114   //     ref processor and abandons any entries on it's
2115   //     discovered lists.
2116   //
2117   // * For the STW processor:
2118   //   * Non MT discovery is enabled at the start of a full GC.
2119   //   * Processing and enqueueing during a full GC is non-MT.
2120   //   * During a full GC, references are processed after marking.
2121   //
2122   //   * Discovery (may or may not be MT) is enabled at the start
2123   //     of an incremental evacuation pause.
2124   //   * References are processed near the end of a STW evacuation pause.
2125   //   * For both types of GC:
2126   //     * Discovery is atomic - i.e. not concurrent.
2127   //     * Reference discovery will not need a barrier.
2128 
2129   MemRegion mr = reserved_region();
2130 
2131   // Concurrent Mark ref processor
2132   _ref_processor_cm =
2133     new ReferenceProcessor(mr,    // span
2134                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2135                                 // mt processing
2136                            ParallelGCThreads,
2137                                 // degree of mt processing
2138                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2139                                 // mt discovery
2140                            MAX2(ParallelGCThreads, ConcGCThreads),
2141                                 // degree of mt discovery
2142                            false,
2143                                 // Reference discovery is not atomic
2144                            &_is_alive_closure_cm);
2145                                 // is alive closure
2146                                 // (for efficiency/performance)
2147 
2148   // STW ref processor
2149   _ref_processor_stw =
2150     new ReferenceProcessor(mr,    // span
2151                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2152                                 // mt processing
2153                            ParallelGCThreads,
2154                                 // degree of mt processing
2155                            (ParallelGCThreads > 1),
2156                                 // mt discovery
2157                            ParallelGCThreads,
2158                                 // degree of mt discovery
2159                            true,
2160                                 // Reference discovery is atomic
2161                            &_is_alive_closure_stw);
2162                                 // is alive closure
2163                                 // (for efficiency/performance)
2164 }
2165 
2166 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2167   return g1_policy();
2168 }
2169 
2170 size_t G1CollectedHeap::capacity() const {
2171   return _hrm.length() * HeapRegion::GrainBytes;
2172 }
2173 
2174 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2175   hr->reset_gc_time_stamp();
2176 }
2177 
2178 #ifndef PRODUCT
2179 
2180 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2181 private:
2182   unsigned _gc_time_stamp;
2183   bool _failures;
2184 
2185 public:
2186   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2187     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2188 
2189   virtual bool doHeapRegion(HeapRegion* hr) {
2190     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2191     if (_gc_time_stamp != region_gc_time_stamp) {
2192       gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2193                              "expected %d", HR_FORMAT_PARAMS(hr),
2194                              region_gc_time_stamp, _gc_time_stamp);
2195       _failures = true;
2196     }
2197     return false;
2198   }
2199 
2200   bool failures() { return _failures; }
2201 };
2202 
2203 void G1CollectedHeap::check_gc_time_stamps() {
2204   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2205   heap_region_iterate(&cl);
2206   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2207 }
2208 #endif // PRODUCT
2209 
2210 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2211   _cg1r->hot_card_cache()->drain(cl, worker_i);
2212 }
2213 
2214 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2215   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2216   size_t n_completed_buffers = 0;
2217   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2218     n_completed_buffers++;
2219   }
2220   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2221   dcqs.clear_n_completed_buffers();
2222   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2223 }
2224 
2225 // Computes the sum of the storage used by the various regions.
2226 size_t G1CollectedHeap::used() const {
2227   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2228   if (_archive_allocator != NULL) {
2229     result += _archive_allocator->used();
2230   }
2231   return result;
2232 }
2233 
2234 size_t G1CollectedHeap::used_unlocked() const {
2235   return _summary_bytes_used;
2236 }
2237 
2238 class SumUsedClosure: public HeapRegionClosure {
2239   size_t _used;
2240 public:
2241   SumUsedClosure() : _used(0) {}
2242   bool doHeapRegion(HeapRegion* r) {
2243     _used += r->used();
2244     return false;
2245   }
2246   size_t result() { return _used; }
2247 };
2248 
2249 size_t G1CollectedHeap::recalculate_used() const {
2250   double recalculate_used_start = os::elapsedTime();
2251 
2252   SumUsedClosure blk;
2253   heap_region_iterate(&blk);
2254 
2255   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2256   return blk.result();
2257 }
2258 
2259 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2260   switch (cause) {
2261     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2262     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2263     case GCCause::_dcmd_gc_run:             return ExplicitGCInvokesConcurrent;
2264     case GCCause::_g1_humongous_allocation: return true;
2265     case GCCause::_update_allocation_context_stats_inc: return true;
2266     case GCCause::_wb_conc_mark:            return true;
2267     default:                                return false;
2268   }
2269 }
2270 
2271 #ifndef PRODUCT
2272 void G1CollectedHeap::allocate_dummy_regions() {
2273   // Let's fill up most of the region
2274   size_t word_size = HeapRegion::GrainWords - 1024;
2275   // And as a result the region we'll allocate will be humongous.
2276   guarantee(is_humongous(word_size), "sanity");
2277 
2278   // _filler_array_max_size is set to humongous object threshold
2279   // but temporarily change it to use CollectedHeap::fill_with_object().
2280   SizeTFlagSetting fs(_filler_array_max_size, word_size);
2281 
2282   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2283     // Let's use the existing mechanism for the allocation
2284     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2285                                                  AllocationContext::system());
2286     if (dummy_obj != NULL) {
2287       MemRegion mr(dummy_obj, word_size);
2288       CollectedHeap::fill_with_object(mr);
2289     } else {
2290       // If we can't allocate once, we probably cannot allocate
2291       // again. Let's get out of the loop.
2292       break;
2293     }
2294   }
2295 }
2296 #endif // !PRODUCT
2297 
2298 void G1CollectedHeap::increment_old_marking_cycles_started() {
2299   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2300          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2301          "Wrong marking cycle count (started: %d, completed: %d)",
2302          _old_marking_cycles_started, _old_marking_cycles_completed);
2303 
2304   _old_marking_cycles_started++;
2305 }
2306 
2307 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2308   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2309 
2310   // We assume that if concurrent == true, then the caller is a
2311   // concurrent thread that was joined the Suspendible Thread
2312   // Set. If there's ever a cheap way to check this, we should add an
2313   // assert here.
2314 
2315   // Given that this method is called at the end of a Full GC or of a
2316   // concurrent cycle, and those can be nested (i.e., a Full GC can
2317   // interrupt a concurrent cycle), the number of full collections
2318   // completed should be either one (in the case where there was no
2319   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2320   // behind the number of full collections started.
2321 
2322   // This is the case for the inner caller, i.e. a Full GC.
2323   assert(concurrent ||
2324          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2325          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2326          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2327          "is inconsistent with _old_marking_cycles_completed = %u",
2328          _old_marking_cycles_started, _old_marking_cycles_completed);
2329 
2330   // This is the case for the outer caller, i.e. the concurrent cycle.
2331   assert(!concurrent ||
2332          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2333          "for outer caller (concurrent cycle): "
2334          "_old_marking_cycles_started = %u "
2335          "is inconsistent with _old_marking_cycles_completed = %u",
2336          _old_marking_cycles_started, _old_marking_cycles_completed);
2337 
2338   _old_marking_cycles_completed += 1;
2339 
2340   // We need to clear the "in_progress" flag in the CM thread before
2341   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2342   // is set) so that if a waiter requests another System.gc() it doesn't
2343   // incorrectly see that a marking cycle is still in progress.
2344   if (concurrent) {
2345     _cmThread->set_idle();
2346   }
2347 
2348   // This notify_all() will ensure that a thread that called
2349   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2350   // and it's waiting for a full GC to finish will be woken up. It is
2351   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2352   FullGCCount_lock->notify_all();
2353 }
2354 
2355 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2356   GCIdMarkAndRestore conc_gc_id_mark;
2357   collector_state()->set_concurrent_cycle_started(true);
2358   _gc_timer_cm->register_gc_start(start_time);
2359 
2360   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2361   trace_heap_before_gc(_gc_tracer_cm);
2362   _cmThread->set_gc_id(GCId::current());
2363 }
2364 
2365 void G1CollectedHeap::register_concurrent_cycle_end() {
2366   if (collector_state()->concurrent_cycle_started()) {
2367     GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2368     if (_cm->has_aborted()) {
2369       _gc_tracer_cm->report_concurrent_mode_failure();
2370     }
2371 
2372     _gc_timer_cm->register_gc_end();
2373     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2374 
2375     // Clear state variables to prepare for the next concurrent cycle.
2376      collector_state()->set_concurrent_cycle_started(false);
2377     _heap_summary_sent = false;
2378   }
2379 }
2380 
2381 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2382   if (collector_state()->concurrent_cycle_started()) {
2383     // This function can be called when:
2384     //  the cleanup pause is run
2385     //  the concurrent cycle is aborted before the cleanup pause.
2386     //  the concurrent cycle is aborted after the cleanup pause,
2387     //   but before the concurrent cycle end has been registered.
2388     // Make sure that we only send the heap information once.
2389     if (!_heap_summary_sent) {
2390       GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2391       trace_heap_after_gc(_gc_tracer_cm);
2392       _heap_summary_sent = true;
2393     }
2394   }
2395 }
2396 
2397 void G1CollectedHeap::collect(GCCause::Cause cause) {
2398   assert_heap_not_locked();
2399 
2400   uint gc_count_before;
2401   uint old_marking_count_before;
2402   uint full_gc_count_before;
2403   bool retry_gc;
2404 
2405   do {
2406     retry_gc = false;
2407 
2408     {
2409       MutexLocker ml(Heap_lock);
2410 
2411       // Read the GC count while holding the Heap_lock
2412       gc_count_before = total_collections();
2413       full_gc_count_before = total_full_collections();
2414       old_marking_count_before = _old_marking_cycles_started;
2415     }
2416 
2417     if (should_do_concurrent_full_gc(cause)) {
2418       // Schedule an initial-mark evacuation pause that will start a
2419       // concurrent cycle. We're setting word_size to 0 which means that
2420       // we are not requesting a post-GC allocation.
2421       VM_G1IncCollectionPause op(gc_count_before,
2422                                  0,     /* word_size */
2423                                  true,  /* should_initiate_conc_mark */
2424                                  g1_policy()->max_pause_time_ms(),
2425                                  cause);
2426       op.set_allocation_context(AllocationContext::current());
2427 
2428       VMThread::execute(&op);
2429       if (!op.pause_succeeded()) {
2430         if (old_marking_count_before == _old_marking_cycles_started) {
2431           retry_gc = op.should_retry_gc();
2432         } else {
2433           // A Full GC happened while we were trying to schedule the
2434           // initial-mark GC. No point in starting a new cycle given
2435           // that the whole heap was collected anyway.
2436         }
2437 
2438         if (retry_gc) {
2439           if (GC_locker::is_active_and_needs_gc()) {
2440             GC_locker::stall_until_clear();
2441           }
2442         }
2443       }
2444     } else {
2445       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2446           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2447 
2448         // Schedule a standard evacuation pause. We're setting word_size
2449         // to 0 which means that we are not requesting a post-GC allocation.
2450         VM_G1IncCollectionPause op(gc_count_before,
2451                                    0,     /* word_size */
2452                                    false, /* should_initiate_conc_mark */
2453                                    g1_policy()->max_pause_time_ms(),
2454                                    cause);
2455         VMThread::execute(&op);
2456       } else {
2457         // Schedule a Full GC.
2458         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2459         VMThread::execute(&op);
2460       }
2461     }
2462   } while (retry_gc);
2463 }
2464 
2465 bool G1CollectedHeap::is_in(const void* p) const {
2466   if (_hrm.reserved().contains(p)) {
2467     // Given that we know that p is in the reserved space,
2468     // heap_region_containing() should successfully
2469     // return the containing region.
2470     HeapRegion* hr = heap_region_containing(p);
2471     return hr->is_in(p);
2472   } else {
2473     return false;
2474   }
2475 }
2476 
2477 #ifdef ASSERT
2478 bool G1CollectedHeap::is_in_exact(const void* p) const {
2479   bool contains = reserved_region().contains(p);
2480   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2481   if (contains && available) {
2482     return true;
2483   } else {
2484     return false;
2485   }
2486 }
2487 #endif
2488 
2489 bool G1CollectedHeap::obj_in_cs(oop obj) {
2490   HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2491   return r != NULL && r->in_collection_set();
2492 }
2493 
2494 // Iteration functions.
2495 
2496 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2497 
2498 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2499   ExtendedOopClosure* _cl;
2500 public:
2501   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2502   bool doHeapRegion(HeapRegion* r) {
2503     if (!r->is_continues_humongous()) {
2504       r->oop_iterate(_cl);
2505     }
2506     return false;
2507   }
2508 };
2509 
2510 // Iterates an ObjectClosure over all objects within a HeapRegion.
2511 
2512 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2513   ObjectClosure* _cl;
2514 public:
2515   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2516   bool doHeapRegion(HeapRegion* r) {
2517     if (!r->is_continues_humongous()) {
2518       r->object_iterate(_cl);
2519     }
2520     return false;
2521   }
2522 };
2523 
2524 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2525   IterateObjectClosureRegionClosure blk(cl);
2526   heap_region_iterate(&blk);
2527 }
2528 
2529 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2530   _hrm.iterate(cl);
2531 }
2532 
2533 void
2534 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2535                                          uint worker_id,
2536                                          HeapRegionClaimer *hrclaimer,
2537                                          bool concurrent) const {
2538   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2539 }
2540 
2541 // Clear the cached CSet starting regions and (more importantly)
2542 // the time stamps. Called when we reset the GC time stamp.
2543 void G1CollectedHeap::clear_cset_start_regions() {
2544   assert(_worker_cset_start_region != NULL, "sanity");
2545   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2546 
2547   for (uint i = 0; i < ParallelGCThreads; i++) {
2548     _worker_cset_start_region[i] = NULL;
2549     _worker_cset_start_region_time_stamp[i] = 0;
2550   }
2551 }
2552 
2553 // Given the id of a worker, obtain or calculate a suitable
2554 // starting region for iterating over the current collection set.
2555 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2556   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2557 
2558   HeapRegion* result = NULL;
2559   unsigned gc_time_stamp = get_gc_time_stamp();
2560 
2561   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2562     // Cached starting region for current worker was set
2563     // during the current pause - so it's valid.
2564     // Note: the cached starting heap region may be NULL
2565     // (when the collection set is empty).
2566     result = _worker_cset_start_region[worker_i];
2567     assert(result == NULL || result->in_collection_set(), "sanity");
2568     return result;
2569   }
2570 
2571   // The cached entry was not valid so let's calculate
2572   // a suitable starting heap region for this worker.
2573 
2574   // We want the parallel threads to start their collection
2575   // set iteration at different collection set regions to
2576   // avoid contention.
2577   // If we have:
2578   //          n collection set regions
2579   //          p threads
2580   // Then thread t will start at region floor ((t * n) / p)
2581 
2582   result = g1_policy()->collection_set();
2583   uint cs_size = g1_policy()->cset_region_length();
2584   uint active_workers = workers()->active_workers();
2585 
2586   uint end_ind   = (cs_size * worker_i) / active_workers;
2587   uint start_ind = 0;
2588 
2589   if (worker_i > 0 &&
2590       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2591     // Previous workers starting region is valid
2592     // so let's iterate from there
2593     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2594     result = _worker_cset_start_region[worker_i - 1];
2595   }
2596 
2597   for (uint i = start_ind; i < end_ind; i++) {
2598     result = result->next_in_collection_set();
2599   }
2600 
2601   // Note: the calculated starting heap region may be NULL
2602   // (when the collection set is empty).
2603   assert(result == NULL || result->in_collection_set(), "sanity");
2604   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2605          "should be updated only once per pause");
2606   _worker_cset_start_region[worker_i] = result;
2607   OrderAccess::storestore();
2608   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2609   return result;
2610 }
2611 
2612 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2613   HeapRegion* r = g1_policy()->collection_set();
2614   while (r != NULL) {
2615     HeapRegion* next = r->next_in_collection_set();
2616     if (cl->doHeapRegion(r)) {
2617       cl->incomplete();
2618       return;
2619     }
2620     r = next;
2621   }
2622 }
2623 
2624 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2625                                                   HeapRegionClosure *cl) {
2626   if (r == NULL) {
2627     // The CSet is empty so there's nothing to do.
2628     return;
2629   }
2630 
2631   assert(r->in_collection_set(),
2632          "Start region must be a member of the collection set.");
2633   HeapRegion* cur = r;
2634   while (cur != NULL) {
2635     HeapRegion* next = cur->next_in_collection_set();
2636     if (cl->doHeapRegion(cur) && false) {
2637       cl->incomplete();
2638       return;
2639     }
2640     cur = next;
2641   }
2642   cur = g1_policy()->collection_set();
2643   while (cur != r) {
2644     HeapRegion* next = cur->next_in_collection_set();
2645     if (cl->doHeapRegion(cur) && false) {
2646       cl->incomplete();
2647       return;
2648     }
2649     cur = next;
2650   }
2651 }
2652 
2653 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2654   HeapRegion* result = _hrm.next_region_in_heap(from);
2655   while (result != NULL && result->is_pinned()) {
2656     result = _hrm.next_region_in_heap(result);
2657   }
2658   return result;
2659 }
2660 
2661 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2662   HeapRegion* hr = heap_region_containing(addr);
2663   return hr->block_start(addr);
2664 }
2665 
2666 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2667   HeapRegion* hr = heap_region_containing(addr);
2668   return hr->block_size(addr);
2669 }
2670 
2671 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2672   HeapRegion* hr = heap_region_containing(addr);
2673   return hr->block_is_obj(addr);
2674 }
2675 
2676 bool G1CollectedHeap::supports_tlab_allocation() const {
2677   return true;
2678 }
2679 
2680 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2681   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2682 }
2683 
2684 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2685   return young_list()->eden_used_bytes();
2686 }
2687 
2688 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2689 // must be equal to the humongous object limit.
2690 size_t G1CollectedHeap::max_tlab_size() const {
2691   return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2692 }
2693 
2694 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2695   AllocationContext_t context = AllocationContext::current();
2696   return _allocator->unsafe_max_tlab_alloc(context);
2697 }
2698 
2699 size_t G1CollectedHeap::max_capacity() const {
2700   return _hrm.reserved().byte_size();
2701 }
2702 
2703 jlong G1CollectedHeap::millis_since_last_gc() {
2704   // assert(false, "NYI");
2705   return 0;
2706 }
2707 
2708 void G1CollectedHeap::prepare_for_verify() {
2709   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2710     ensure_parsability(false);
2711   }
2712   g1_rem_set()->prepare_for_verify();
2713 }
2714 
2715 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2716                                               VerifyOption vo) {
2717   switch (vo) {
2718   case VerifyOption_G1UsePrevMarking:
2719     return hr->obj_allocated_since_prev_marking(obj);
2720   case VerifyOption_G1UseNextMarking:
2721     return hr->obj_allocated_since_next_marking(obj);
2722   case VerifyOption_G1UseMarkWord:
2723     return false;
2724   default:
2725     ShouldNotReachHere();
2726   }
2727   return false; // keep some compilers happy
2728 }
2729 
2730 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2731   switch (vo) {
2732   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2733   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2734   case VerifyOption_G1UseMarkWord:    return NULL;
2735   default:                            ShouldNotReachHere();
2736   }
2737   return NULL; // keep some compilers happy
2738 }
2739 
2740 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2741   switch (vo) {
2742   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2743   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2744   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
2745   default:                            ShouldNotReachHere();
2746   }
2747   return false; // keep some compilers happy
2748 }
2749 
2750 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2751   switch (vo) {
2752   case VerifyOption_G1UsePrevMarking: return "PTAMS";
2753   case VerifyOption_G1UseNextMarking: return "NTAMS";
2754   case VerifyOption_G1UseMarkWord:    return "NONE";
2755   default:                            ShouldNotReachHere();
2756   }
2757   return NULL; // keep some compilers happy
2758 }
2759 
2760 class VerifyRootsClosure: public OopClosure {
2761 private:
2762   G1CollectedHeap* _g1h;
2763   VerifyOption     _vo;
2764   bool             _failures;
2765 public:
2766   // _vo == UsePrevMarking -> use "prev" marking information,
2767   // _vo == UseNextMarking -> use "next" marking information,
2768   // _vo == UseMarkWord    -> use mark word from object header.
2769   VerifyRootsClosure(VerifyOption vo) :
2770     _g1h(G1CollectedHeap::heap()),
2771     _vo(vo),
2772     _failures(false) { }
2773 
2774   bool failures() { return _failures; }
2775 
2776   template <class T> void do_oop_nv(T* p) {
2777     T heap_oop = oopDesc::load_heap_oop(p);
2778     if (!oopDesc::is_null(heap_oop)) {
2779       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2780       if (_g1h->is_obj_dead_cond(obj, _vo)) {
2781         gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2782                                "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2783         if (_vo == VerifyOption_G1UseMarkWord) {
2784           gclog_or_tty->print_cr("  Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2785         }
2786         obj->print_on(gclog_or_tty);
2787         _failures = true;
2788       }
2789     }
2790   }
2791 
2792   void do_oop(oop* p)       { do_oop_nv(p); }
2793   void do_oop(narrowOop* p) { do_oop_nv(p); }
2794 };
2795 
2796 class G1VerifyCodeRootOopClosure: public OopClosure {
2797   G1CollectedHeap* _g1h;
2798   OopClosure* _root_cl;
2799   nmethod* _nm;
2800   VerifyOption _vo;
2801   bool _failures;
2802 
2803   template <class T> void do_oop_work(T* p) {
2804     // First verify that this root is live
2805     _root_cl->do_oop(p);
2806 
2807     if (!G1VerifyHeapRegionCodeRoots) {
2808       // We're not verifying the code roots attached to heap region.
2809       return;
2810     }
2811 
2812     // Don't check the code roots during marking verification in a full GC
2813     if (_vo == VerifyOption_G1UseMarkWord) {
2814       return;
2815     }
2816 
2817     // Now verify that the current nmethod (which contains p) is
2818     // in the code root list of the heap region containing the
2819     // object referenced by p.
2820 
2821     T heap_oop = oopDesc::load_heap_oop(p);
2822     if (!oopDesc::is_null(heap_oop)) {
2823       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2824 
2825       // Now fetch the region containing the object
2826       HeapRegion* hr = _g1h->heap_region_containing(obj);
2827       HeapRegionRemSet* hrrs = hr->rem_set();
2828       // Verify that the strong code root list for this region
2829       // contains the nmethod
2830       if (!hrrs->strong_code_roots_list_contains(_nm)) {
2831         gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2832                                "from nmethod " PTR_FORMAT " not in strong "
2833                                "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2834                                p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2835         _failures = true;
2836       }
2837     }
2838   }
2839 
2840 public:
2841   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2842     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2843 
2844   void do_oop(oop* p) { do_oop_work(p); }
2845   void do_oop(narrowOop* p) { do_oop_work(p); }
2846 
2847   void set_nmethod(nmethod* nm) { _nm = nm; }
2848   bool failures() { return _failures; }
2849 };
2850 
2851 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2852   G1VerifyCodeRootOopClosure* _oop_cl;
2853 
2854 public:
2855   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2856     _oop_cl(oop_cl) {}
2857 
2858   void do_code_blob(CodeBlob* cb) {
2859     nmethod* nm = cb->as_nmethod_or_null();
2860     if (nm != NULL) {
2861       _oop_cl->set_nmethod(nm);
2862       nm->oops_do(_oop_cl);
2863     }
2864   }
2865 };
2866 
2867 class YoungRefCounterClosure : public OopClosure {
2868   G1CollectedHeap* _g1h;
2869   int              _count;
2870  public:
2871   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2872   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
2873   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2874 
2875   int count() { return _count; }
2876   void reset_count() { _count = 0; };
2877 };
2878 
2879 class VerifyKlassClosure: public KlassClosure {
2880   YoungRefCounterClosure _young_ref_counter_closure;
2881   OopClosure *_oop_closure;
2882  public:
2883   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2884   void do_klass(Klass* k) {
2885     k->oops_do(_oop_closure);
2886 
2887     _young_ref_counter_closure.reset_count();
2888     k->oops_do(&_young_ref_counter_closure);
2889     if (_young_ref_counter_closure.count() > 0) {
2890       guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2891     }
2892   }
2893 };
2894 
2895 class VerifyLivenessOopClosure: public OopClosure {
2896   G1CollectedHeap* _g1h;
2897   VerifyOption _vo;
2898 public:
2899   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2900     _g1h(g1h), _vo(vo)
2901   { }
2902   void do_oop(narrowOop *p) { do_oop_work(p); }
2903   void do_oop(      oop *p) { do_oop_work(p); }
2904 
2905   template <class T> void do_oop_work(T *p) {
2906     oop obj = oopDesc::load_decode_heap_oop(p);
2907     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2908               "Dead object referenced by a not dead object");
2909   }
2910 };
2911 
2912 class VerifyObjsInRegionClosure: public ObjectClosure {
2913 private:
2914   G1CollectedHeap* _g1h;
2915   size_t _live_bytes;
2916   HeapRegion *_hr;
2917   VerifyOption _vo;
2918 public:
2919   // _vo == UsePrevMarking -> use "prev" marking information,
2920   // _vo == UseNextMarking -> use "next" marking information,
2921   // _vo == UseMarkWord    -> use mark word from object header.
2922   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2923     : _live_bytes(0), _hr(hr), _vo(vo) {
2924     _g1h = G1CollectedHeap::heap();
2925   }
2926   void do_object(oop o) {
2927     VerifyLivenessOopClosure isLive(_g1h, _vo);
2928     assert(o != NULL, "Huh?");
2929     if (!_g1h->is_obj_dead_cond(o, _vo)) {
2930       // If the object is alive according to the mark word,
2931       // then verify that the marking information agrees.
2932       // Note we can't verify the contra-positive of the
2933       // above: if the object is dead (according to the mark
2934       // word), it may not be marked, or may have been marked
2935       // but has since became dead, or may have been allocated
2936       // since the last marking.
2937       if (_vo == VerifyOption_G1UseMarkWord) {
2938         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2939       }
2940 
2941       o->oop_iterate_no_header(&isLive);
2942       if (!_hr->obj_allocated_since_prev_marking(o)) {
2943         size_t obj_size = o->size();    // Make sure we don't overflow
2944         _live_bytes += (obj_size * HeapWordSize);
2945       }
2946     }
2947   }
2948   size_t live_bytes() { return _live_bytes; }
2949 };
2950 
2951 class VerifyArchiveOopClosure: public OopClosure {
2952 public:
2953   VerifyArchiveOopClosure(HeapRegion *hr) { }
2954   void do_oop(narrowOop *p) { do_oop_work(p); }
2955   void do_oop(      oop *p) { do_oop_work(p); }
2956 
2957   template <class T> void do_oop_work(T *p) {
2958     oop obj = oopDesc::load_decode_heap_oop(p);
2959     guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2960               "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2961               p2i(p), p2i(obj));
2962   }
2963 };
2964 
2965 class VerifyArchiveRegionClosure: public ObjectClosure {
2966 public:
2967   VerifyArchiveRegionClosure(HeapRegion *hr) { }
2968   // Verify that all object pointers are to archive regions.
2969   void do_object(oop o) {
2970     VerifyArchiveOopClosure checkOop(NULL);
2971     assert(o != NULL, "Should not be here for NULL oops");
2972     o->oop_iterate_no_header(&checkOop);
2973   }
2974 };
2975 
2976 class VerifyRegionClosure: public HeapRegionClosure {
2977 private:
2978   bool             _par;
2979   VerifyOption     _vo;
2980   bool             _failures;
2981 public:
2982   // _vo == UsePrevMarking -> use "prev" marking information,
2983   // _vo == UseNextMarking -> use "next" marking information,
2984   // _vo == UseMarkWord    -> use mark word from object header.
2985   VerifyRegionClosure(bool par, VerifyOption vo)
2986     : _par(par),
2987       _vo(vo),
2988       _failures(false) {}
2989 
2990   bool failures() {
2991     return _failures;
2992   }
2993 
2994   bool doHeapRegion(HeapRegion* r) {
2995     // For archive regions, verify there are no heap pointers to
2996     // non-pinned regions. For all others, verify liveness info.
2997     if (r->is_archive()) {
2998       VerifyArchiveRegionClosure verify_oop_pointers(r);
2999       r->object_iterate(&verify_oop_pointers);
3000       return true;
3001     }
3002     if (!r->is_continues_humongous()) {
3003       bool failures = false;
3004       r->verify(_vo, &failures);
3005       if (failures) {
3006         _failures = true;
3007       } else if (!r->is_starts_humongous()) {
3008         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3009         r->object_iterate(&not_dead_yet_cl);
3010         if (_vo != VerifyOption_G1UseNextMarking) {
3011           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3012             gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3013                                    "max_live_bytes " SIZE_FORMAT " "
3014                                    "< calculated " SIZE_FORMAT,
3015                                    p2i(r->bottom()), p2i(r->end()),
3016                                    r->max_live_bytes(),
3017                                  not_dead_yet_cl.live_bytes());
3018             _failures = true;
3019           }
3020         } else {
3021           // When vo == UseNextMarking we cannot currently do a sanity
3022           // check on the live bytes as the calculation has not been
3023           // finalized yet.
3024         }
3025       }
3026     }
3027     return false; // stop the region iteration if we hit a failure
3028   }
3029 };
3030 
3031 // This is the task used for parallel verification of the heap regions
3032 
3033 class G1ParVerifyTask: public AbstractGangTask {
3034 private:
3035   G1CollectedHeap*  _g1h;
3036   VerifyOption      _vo;
3037   bool              _failures;
3038   HeapRegionClaimer _hrclaimer;
3039 
3040 public:
3041   // _vo == UsePrevMarking -> use "prev" marking information,
3042   // _vo == UseNextMarking -> use "next" marking information,
3043   // _vo == UseMarkWord    -> use mark word from object header.
3044   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3045       AbstractGangTask("Parallel verify task"),
3046       _g1h(g1h),
3047       _vo(vo),
3048       _failures(false),
3049       _hrclaimer(g1h->workers()->active_workers()) {}
3050 
3051   bool failures() {
3052     return _failures;
3053   }
3054 
3055   void work(uint worker_id) {
3056     HandleMark hm;
3057     VerifyRegionClosure blk(true, _vo);
3058     _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3059     if (blk.failures()) {
3060       _failures = true;
3061     }
3062   }
3063 };
3064 
3065 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3066   if (SafepointSynchronize::is_at_safepoint()) {
3067     assert(Thread::current()->is_VM_thread(),
3068            "Expected to be executed serially by the VM thread at this point");
3069 
3070     if (!silent) { gclog_or_tty->print("Roots "); }
3071     VerifyRootsClosure rootsCl(vo);
3072     VerifyKlassClosure klassCl(this, &rootsCl);
3073     CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3074 
3075     // We apply the relevant closures to all the oops in the
3076     // system dictionary, class loader data graph, the string table
3077     // and the nmethods in the code cache.
3078     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3079     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3080 
3081     {
3082       G1RootProcessor root_processor(this, 1);
3083       root_processor.process_all_roots(&rootsCl,
3084                                        &cldCl,
3085                                        &blobsCl);
3086     }
3087 
3088     bool failures = rootsCl.failures() || codeRootsCl.failures();
3089 
3090     if (vo != VerifyOption_G1UseMarkWord) {
3091       // If we're verifying during a full GC then the region sets
3092       // will have been torn down at the start of the GC. Therefore
3093       // verifying the region sets will fail. So we only verify
3094       // the region sets when not in a full GC.
3095       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3096       verify_region_sets();
3097     }
3098 
3099     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3100     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3101 
3102       G1ParVerifyTask task(this, vo);
3103       workers()->run_task(&task);
3104       if (task.failures()) {
3105         failures = true;
3106       }
3107 
3108     } else {
3109       VerifyRegionClosure blk(false, vo);
3110       heap_region_iterate(&blk);
3111       if (blk.failures()) {
3112         failures = true;
3113       }
3114     }
3115 
3116     if (G1StringDedup::is_enabled()) {
3117       if (!silent) gclog_or_tty->print("StrDedup ");
3118       G1StringDedup::verify();
3119     }
3120 
3121     if (failures) {
3122       gclog_or_tty->print_cr("Heap:");
3123       // It helps to have the per-region information in the output to
3124       // help us track down what went wrong. This is why we call
3125       // print_extended_on() instead of print_on().
3126       print_extended_on(gclog_or_tty);
3127       gclog_or_tty->cr();
3128       gclog_or_tty->flush();
3129     }
3130     guarantee(!failures, "there should not have been any failures");
3131   } else {
3132     if (!silent) {
3133       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3134       if (G1StringDedup::is_enabled()) {
3135         gclog_or_tty->print(", StrDedup");
3136       }
3137       gclog_or_tty->print(") ");
3138     }
3139   }
3140 }
3141 
3142 void G1CollectedHeap::verify(bool silent) {
3143   verify(silent, VerifyOption_G1UsePrevMarking);
3144 }
3145 
3146 double G1CollectedHeap::verify(bool guard, const char* msg) {
3147   double verify_time_ms = 0.0;
3148 
3149   if (guard && total_collections() >= VerifyGCStartAt) {
3150     double verify_start = os::elapsedTime();
3151     HandleMark hm;  // Discard invalid handles created during verification
3152     prepare_for_verify();
3153     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3154     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3155   }
3156 
3157   return verify_time_ms;
3158 }
3159 
3160 void G1CollectedHeap::verify_before_gc() {
3161   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3162   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3163 }
3164 
3165 void G1CollectedHeap::verify_after_gc() {
3166   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3167   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3168 }
3169 
3170 class PrintRegionClosure: public HeapRegionClosure {
3171   outputStream* _st;
3172 public:
3173   PrintRegionClosure(outputStream* st) : _st(st) {}
3174   bool doHeapRegion(HeapRegion* r) {
3175     r->print_on(_st);
3176     return false;
3177   }
3178 };
3179 
3180 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3181                                        const HeapRegion* hr,
3182                                        const VerifyOption vo) const {
3183   switch (vo) {
3184   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3185   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3186   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
3187   default:                            ShouldNotReachHere();
3188   }
3189   return false; // keep some compilers happy
3190 }
3191 
3192 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3193                                        const VerifyOption vo) const {
3194   switch (vo) {
3195   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3196   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3197   case VerifyOption_G1UseMarkWord: {
3198     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3199     return !obj->is_gc_marked() && !hr->is_archive();
3200   }
3201   default:                            ShouldNotReachHere();
3202   }
3203   return false; // keep some compilers happy
3204 }
3205 
3206 void G1CollectedHeap::print_on(outputStream* st) const {
3207   st->print(" %-20s", "garbage-first heap");
3208   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3209             capacity()/K, used_unlocked()/K);
3210   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3211             p2i(_hrm.reserved().start()),
3212             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3213             p2i(_hrm.reserved().end()));
3214   st->cr();
3215   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3216   uint young_regions = _young_list->length();
3217   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3218             (size_t) young_regions * HeapRegion::GrainBytes / K);
3219   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3220   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3221             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3222   st->cr();
3223   MetaspaceAux::print_on(st);
3224 }
3225 
3226 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3227   print_on(st);
3228 
3229   // Print the per-region information.
3230   st->cr();
3231   st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3232                "HS=humongous(starts), HC=humongous(continues), "
3233                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3234                "PTAMS=previous top-at-mark-start, "
3235                "NTAMS=next top-at-mark-start)");
3236   PrintRegionClosure blk(st);
3237   heap_region_iterate(&blk);
3238 }
3239 
3240 void G1CollectedHeap::print_on_error(outputStream* st) const {
3241   this->CollectedHeap::print_on_error(st);
3242 
3243   if (_cm != NULL) {
3244     st->cr();
3245     _cm->print_on_error(st);
3246   }
3247 }
3248 
3249 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3250   workers()->print_worker_threads_on(st);
3251   _cmThread->print_on(st);
3252   st->cr();
3253   _cm->print_worker_threads_on(st);
3254   _cg1r->print_worker_threads_on(st);
3255   if (G1StringDedup::is_enabled()) {
3256     G1StringDedup::print_worker_threads_on(st);
3257   }
3258 }
3259 
3260 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3261   workers()->threads_do(tc);
3262   tc->do_thread(_cmThread);
3263   _cg1r->threads_do(tc);
3264   if (G1StringDedup::is_enabled()) {
3265     G1StringDedup::threads_do(tc);
3266   }
3267 }
3268 
3269 void G1CollectedHeap::print_tracing_info() const {
3270   // We'll overload this to mean "trace GC pause statistics."
3271   if (TraceYoungGenTime || TraceOldGenTime) {
3272     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3273     // to that.
3274     g1_policy()->print_tracing_info();
3275   }
3276   if (G1SummarizeRSetStats) {
3277     g1_rem_set()->print_summary_info();
3278   }
3279   if (G1SummarizeConcMark) {
3280     concurrent_mark()->print_summary_info();
3281   }
3282   g1_policy()->print_yg_surv_rate_info();
3283 }
3284 
3285 #ifndef PRODUCT
3286 // Helpful for debugging RSet issues.
3287 
3288 class PrintRSetsClosure : public HeapRegionClosure {
3289 private:
3290   const char* _msg;
3291   size_t _occupied_sum;
3292 
3293 public:
3294   bool doHeapRegion(HeapRegion* r) {
3295     HeapRegionRemSet* hrrs = r->rem_set();
3296     size_t occupied = hrrs->occupied();
3297     _occupied_sum += occupied;
3298 
3299     gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3300                            HR_FORMAT_PARAMS(r));
3301     if (occupied == 0) {
3302       gclog_or_tty->print_cr("  RSet is empty");
3303     } else {
3304       hrrs->print();
3305     }
3306     gclog_or_tty->print_cr("----------");
3307     return false;
3308   }
3309 
3310   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3311     gclog_or_tty->cr();
3312     gclog_or_tty->print_cr("========================================");
3313     gclog_or_tty->print_cr("%s", msg);
3314     gclog_or_tty->cr();
3315   }
3316 
3317   ~PrintRSetsClosure() {
3318     gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3319     gclog_or_tty->print_cr("========================================");
3320     gclog_or_tty->cr();
3321   }
3322 };
3323 
3324 void G1CollectedHeap::print_cset_rsets() {
3325   PrintRSetsClosure cl("Printing CSet RSets");
3326   collection_set_iterate(&cl);
3327 }
3328 
3329 void G1CollectedHeap::print_all_rsets() {
3330   PrintRSetsClosure cl("Printing All RSets");;
3331   heap_region_iterate(&cl);
3332 }
3333 #endif // PRODUCT
3334 
3335 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3336   YoungList* young_list = heap()->young_list();
3337 
3338   size_t eden_used_bytes = young_list->eden_used_bytes();
3339   size_t survivor_used_bytes = young_list->survivor_used_bytes();
3340 
3341   size_t eden_capacity_bytes =
3342     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3343 
3344   VirtualSpaceSummary heap_summary = create_heap_space_summary();
3345   return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3346 }
3347 
3348 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3349   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3350                        stats->unused(), stats->used(), stats->region_end_waste(),
3351                        stats->regions_filled(), stats->direct_allocated(),
3352                        stats->failure_used(), stats->failure_waste());
3353 }
3354 
3355 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3356   const G1HeapSummary& heap_summary = create_g1_heap_summary();
3357   gc_tracer->report_gc_heap_summary(when, heap_summary);
3358 
3359   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3360   gc_tracer->report_metaspace_summary(when, metaspace_summary);
3361 }
3362 
3363 
3364 G1CollectedHeap* G1CollectedHeap::heap() {
3365   CollectedHeap* heap = Universe::heap();
3366   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3367   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3368   return (G1CollectedHeap*)heap;
3369 }
3370 
3371 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3372   // always_do_update_barrier = false;
3373   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3374   // Fill TLAB's and such
3375   accumulate_statistics_all_tlabs();
3376   ensure_parsability(true);
3377 
3378   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3379       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3380     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3381   }
3382 }
3383 
3384 void G1CollectedHeap::gc_epilogue(bool full) {
3385 
3386   if (G1SummarizeRSetStats &&
3387       (G1SummarizeRSetStatsPeriod > 0) &&
3388       // we are at the end of the GC. Total collections has already been increased.
3389       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3390     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3391   }
3392 
3393   // FIXME: what is this about?
3394   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3395   // is set.
3396 #if defined(COMPILER2) || INCLUDE_JVMCI
3397   assert(DerivedPointerTable::is_empty(), "derived pointer present");
3398 #endif
3399   // always_do_update_barrier = true;
3400 
3401   resize_all_tlabs();
3402   allocation_context_stats().update(full);
3403 
3404   // We have just completed a GC. Update the soft reference
3405   // policy with the new heap occupancy
3406   Universe::update_heap_info_at_gc();
3407 }
3408 
3409 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3410                                                uint gc_count_before,
3411                                                bool* succeeded,
3412                                                GCCause::Cause gc_cause) {
3413   assert_heap_not_locked_and_not_at_safepoint();
3414   g1_policy()->record_stop_world_start();
3415   VM_G1IncCollectionPause op(gc_count_before,
3416                              word_size,
3417                              false, /* should_initiate_conc_mark */
3418                              g1_policy()->max_pause_time_ms(),
3419                              gc_cause);
3420 
3421   op.set_allocation_context(AllocationContext::current());
3422   VMThread::execute(&op);
3423 
3424   HeapWord* result = op.result();
3425   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3426   assert(result == NULL || ret_succeeded,
3427          "the result should be NULL if the VM did not succeed");
3428   *succeeded = ret_succeeded;
3429 
3430   assert_heap_not_locked();
3431   return result;
3432 }
3433 
3434 void
3435 G1CollectedHeap::doConcurrentMark() {
3436   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3437   if (!_cmThread->in_progress()) {
3438     _cmThread->set_started();
3439     CGC_lock->notify();
3440   }
3441 }
3442 
3443 size_t G1CollectedHeap::pending_card_num() {
3444   size_t extra_cards = 0;
3445   JavaThread *curr = Threads::first();
3446   while (curr != NULL) {
3447     DirtyCardQueue& dcq = curr->dirty_card_queue();
3448     extra_cards += dcq.size();
3449     curr = curr->next();
3450   }
3451   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3452   size_t buffer_size = dcqs.buffer_size();
3453   size_t buffer_num = dcqs.completed_buffers_num();
3454 
3455   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3456   // in bytes - not the number of 'entries'. We need to convert
3457   // into a number of cards.
3458   return (buffer_size * buffer_num + extra_cards) / oopSize;
3459 }
3460 
3461 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3462  private:
3463   size_t _total_humongous;
3464   size_t _candidate_humongous;
3465 
3466   DirtyCardQueue _dcq;
3467 
3468   // We don't nominate objects with many remembered set entries, on
3469   // the assumption that such objects are likely still live.
3470   bool is_remset_small(HeapRegion* region) const {
3471     HeapRegionRemSet* const rset = region->rem_set();
3472     return G1EagerReclaimHumongousObjectsWithStaleRefs
3473       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3474       : rset->is_empty();
3475   }
3476 
3477   bool is_typeArray_region(HeapRegion* region) const {
3478     return oop(region->bottom())->is_typeArray();
3479   }
3480 
3481   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3482     assert(region->is_starts_humongous(), "Must start a humongous object");
3483 
3484     // Candidate selection must satisfy the following constraints
3485     // while concurrent marking is in progress:
3486     //
3487     // * In order to maintain SATB invariants, an object must not be
3488     // reclaimed if it was allocated before the start of marking and
3489     // has not had its references scanned.  Such an object must have
3490     // its references (including type metadata) scanned to ensure no
3491     // live objects are missed by the marking process.  Objects
3492     // allocated after the start of concurrent marking don't need to
3493     // be scanned.
3494     //
3495     // * An object must not be reclaimed if it is on the concurrent
3496     // mark stack.  Objects allocated after the start of concurrent
3497     // marking are never pushed on the mark stack.
3498     //
3499     // Nominating only objects allocated after the start of concurrent
3500     // marking is sufficient to meet both constraints.  This may miss
3501     // some objects that satisfy the constraints, but the marking data
3502     // structures don't support efficiently performing the needed
3503     // additional tests or scrubbing of the mark stack.
3504     //
3505     // However, we presently only nominate is_typeArray() objects.
3506     // A humongous object containing references induces remembered
3507     // set entries on other regions.  In order to reclaim such an
3508     // object, those remembered sets would need to be cleaned up.
3509     //
3510     // We also treat is_typeArray() objects specially, allowing them
3511     // to be reclaimed even if allocated before the start of
3512     // concurrent mark.  For this we rely on mark stack insertion to
3513     // exclude is_typeArray() objects, preventing reclaiming an object
3514     // that is in the mark stack.  We also rely on the metadata for
3515     // such objects to be built-in and so ensured to be kept live.
3516     // Frequent allocation and drop of large binary blobs is an
3517     // important use case for eager reclaim, and this special handling
3518     // may reduce needed headroom.
3519 
3520     return is_typeArray_region(region) && is_remset_small(region);
3521   }
3522 
3523  public:
3524   RegisterHumongousWithInCSetFastTestClosure()
3525   : _total_humongous(0),
3526     _candidate_humongous(0),
3527     _dcq(&JavaThread::dirty_card_queue_set()) {
3528   }
3529 
3530   virtual bool doHeapRegion(HeapRegion* r) {
3531     if (!r->is_starts_humongous()) {
3532       return false;
3533     }
3534     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3535 
3536     bool is_candidate = humongous_region_is_candidate(g1h, r);
3537     uint rindex = r->hrm_index();
3538     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3539     if (is_candidate) {
3540       _candidate_humongous++;
3541       g1h->register_humongous_region_with_cset(rindex);
3542       // Is_candidate already filters out humongous object with large remembered sets.
3543       // If we have a humongous object with a few remembered sets, we simply flush these
3544       // remembered set entries into the DCQS. That will result in automatic
3545       // re-evaluation of their remembered set entries during the following evacuation
3546       // phase.
3547       if (!r->rem_set()->is_empty()) {
3548         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3549                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3550         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3551         HeapRegionRemSetIterator hrrs(r->rem_set());
3552         size_t card_index;
3553         while (hrrs.has_next(card_index)) {
3554           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3555           // The remembered set might contain references to already freed
3556           // regions. Filter out such entries to avoid failing card table
3557           // verification.
3558           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3559             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3560               *card_ptr = CardTableModRefBS::dirty_card_val();
3561               _dcq.enqueue(card_ptr);
3562             }
3563           }
3564         }
3565         assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3566                "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3567                hrrs.n_yielded(), r->rem_set()->occupied());
3568         r->rem_set()->clear_locked();
3569       }
3570       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3571     }
3572     _total_humongous++;
3573 
3574     return false;
3575   }
3576 
3577   size_t total_humongous() const { return _total_humongous; }
3578   size_t candidate_humongous() const { return _candidate_humongous; }
3579 
3580   void flush_rem_set_entries() { _dcq.flush(); }
3581 };
3582 
3583 void G1CollectedHeap::register_humongous_regions_with_cset() {
3584   if (!G1EagerReclaimHumongousObjects) {
3585     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3586     return;
3587   }
3588   double time = os::elapsed_counter();
3589 
3590   // Collect reclaim candidate information and register candidates with cset.
3591   RegisterHumongousWithInCSetFastTestClosure cl;
3592   heap_region_iterate(&cl);
3593 
3594   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3595   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3596                                                                   cl.total_humongous(),
3597                                                                   cl.candidate_humongous());
3598   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3599 
3600   // Finally flush all remembered set entries to re-check into the global DCQS.
3601   cl.flush_rem_set_entries();
3602 }
3603 
3604 #ifdef ASSERT
3605 class VerifyCSetClosure: public HeapRegionClosure {
3606 public:
3607   bool doHeapRegion(HeapRegion* hr) {
3608     // Here we check that the CSet region's RSet is ready for parallel
3609     // iteration. The fields that we'll verify are only manipulated
3610     // when the region is part of a CSet and is collected. Afterwards,
3611     // we reset these fields when we clear the region's RSet (when the
3612     // region is freed) so they are ready when the region is
3613     // re-allocated. The only exception to this is if there's an
3614     // evacuation failure and instead of freeing the region we leave
3615     // it in the heap. In that case, we reset these fields during
3616     // evacuation failure handling.
3617     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3618 
3619     // Here's a good place to add any other checks we'd like to
3620     // perform on CSet regions.
3621     return false;
3622   }
3623 };
3624 #endif // ASSERT
3625 
3626 uint G1CollectedHeap::num_task_queues() const {
3627   return _task_queues->size();
3628 }
3629 
3630 #if TASKQUEUE_STATS
3631 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3632   st->print_raw_cr("GC Task Stats");
3633   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3634   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3635 }
3636 
3637 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3638   print_taskqueue_stats_hdr(st);
3639 
3640   TaskQueueStats totals;
3641   const uint n = num_task_queues();
3642   for (uint i = 0; i < n; ++i) {
3643     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3644     totals += task_queue(i)->stats;
3645   }
3646   st->print_raw("tot "); totals.print(st); st->cr();
3647 
3648   DEBUG_ONLY(totals.verify());
3649 }
3650 
3651 void G1CollectedHeap::reset_taskqueue_stats() {
3652   const uint n = num_task_queues();
3653   for (uint i = 0; i < n; ++i) {
3654     task_queue(i)->stats.reset();
3655   }
3656 }
3657 #endif // TASKQUEUE_STATS
3658 
3659 void G1CollectedHeap::log_gc_header() {
3660   if (!G1Log::fine()) {
3661     return;
3662   }
3663 
3664   gclog_or_tty->gclog_stamp();
3665 
3666   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3667     .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3668     .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3669 
3670   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3671 }
3672 
3673 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3674   if (!G1Log::fine()) {
3675     return;
3676   }
3677 
3678   if (G1Log::finer()) {
3679     if (evacuation_failed()) {
3680       gclog_or_tty->print(" (to-space exhausted)");
3681     }
3682     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3683     g1_policy()->print_phases(pause_time_sec);
3684     g1_policy()->print_detailed_heap_transition();
3685   } else {
3686     if (evacuation_failed()) {
3687       gclog_or_tty->print("--");
3688     }
3689     g1_policy()->print_heap_transition();
3690     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3691   }
3692   gclog_or_tty->flush();
3693 }
3694 
3695 void G1CollectedHeap::wait_for_root_region_scanning() {
3696   double scan_wait_start = os::elapsedTime();
3697   // We have to wait until the CM threads finish scanning the
3698   // root regions as it's the only way to ensure that all the
3699   // objects on them have been correctly scanned before we start
3700   // moving them during the GC.
3701   bool waited = _cm->root_regions()->wait_until_scan_finished();
3702   double wait_time_ms = 0.0;
3703   if (waited) {
3704     double scan_wait_end = os::elapsedTime();
3705     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3706   }
3707   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3708 }
3709 
3710 bool
3711 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3712   assert_at_safepoint(true /* should_be_vm_thread */);
3713   guarantee(!is_gc_active(), "collection is not reentrant");
3714 
3715   if (GC_locker::check_active_before_gc()) {
3716     return false;
3717   }
3718 
3719   _gc_timer_stw->register_gc_start();
3720 
3721   GCIdMark gc_id_mark;
3722   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3723 
3724   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3725   ResourceMark rm;
3726 
3727   wait_for_root_region_scanning();
3728 
3729   G1Log::update_level();
3730   print_heap_before_gc();
3731   trace_heap_before_gc(_gc_tracer_stw);
3732 
3733   verify_region_sets_optional();
3734   verify_dirty_young_regions();
3735 
3736   // This call will decide whether this pause is an initial-mark
3737   // pause. If it is, during_initial_mark_pause() will return true
3738   // for the duration of this pause.
3739   g1_policy()->decide_on_conc_mark_initiation();
3740 
3741   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3742   assert(!collector_state()->during_initial_mark_pause() ||
3743           collector_state()->gcs_are_young(), "sanity");
3744 
3745   // We also do not allow mixed GCs during marking.
3746   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3747 
3748   // Record whether this pause is an initial mark. When the current
3749   // thread has completed its logging output and it's safe to signal
3750   // the CM thread, the flag's value in the policy has been reset.
3751   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3752 
3753   // Inner scope for scope based logging, timers, and stats collection
3754   {
3755     EvacuationInfo evacuation_info;
3756 
3757     if (collector_state()->during_initial_mark_pause()) {
3758       // We are about to start a marking cycle, so we increment the
3759       // full collection counter.
3760       increment_old_marking_cycles_started();
3761       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3762     }
3763 
3764     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3765 
3766     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3767 
3768     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3769                                                                   workers()->active_workers(),
3770                                                                   Threads::number_of_non_daemon_threads());
3771     workers()->set_active_workers(active_workers);
3772 
3773     double pause_start_sec = os::elapsedTime();
3774     g1_policy()->note_gc_start(active_workers);
3775     log_gc_header();
3776 
3777     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3778     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3779 
3780     // If the secondary_free_list is not empty, append it to the
3781     // free_list. No need to wait for the cleanup operation to finish;
3782     // the region allocation code will check the secondary_free_list
3783     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3784     // set, skip this step so that the region allocation code has to
3785     // get entries from the secondary_free_list.
3786     if (!G1StressConcRegionFreeing) {
3787       append_secondary_free_list_if_not_empty_with_lock();
3788     }
3789 
3790     assert(check_young_list_well_formed(), "young list should be well formed");
3791 
3792     // Don't dynamically change the number of GC threads this early.  A value of
3793     // 0 is used to indicate serial work.  When parallel work is done,
3794     // it will be set.
3795 
3796     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3797       IsGCActiveMark x;
3798 
3799       gc_prologue(false);
3800       increment_total_collections(false /* full gc */);
3801       increment_gc_time_stamp();
3802 
3803       verify_before_gc();
3804 
3805       check_bitmaps("GC Start");
3806 
3807 #if defined(COMPILER2) || INCLUDE_JVMCI
3808       DerivedPointerTable::clear();
3809 #endif
3810 
3811       // Please see comment in g1CollectedHeap.hpp and
3812       // G1CollectedHeap::ref_processing_init() to see how
3813       // reference processing currently works in G1.
3814 
3815       // Enable discovery in the STW reference processor
3816       ref_processor_stw()->enable_discovery();
3817 
3818       {
3819         // We want to temporarily turn off discovery by the
3820         // CM ref processor, if necessary, and turn it back on
3821         // on again later if we do. Using a scoped
3822         // NoRefDiscovery object will do this.
3823         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3824 
3825         // Forget the current alloc region (we might even choose it to be part
3826         // of the collection set!).
3827         _allocator->release_mutator_alloc_region();
3828 
3829         // We should call this after we retire the mutator alloc
3830         // region(s) so that all the ALLOC / RETIRE events are generated
3831         // before the start GC event.
3832         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3833 
3834         // This timing is only used by the ergonomics to handle our pause target.
3835         // It is unclear why this should not include the full pause. We will
3836         // investigate this in CR 7178365.
3837         //
3838         // Preserving the old comment here if that helps the investigation:
3839         //
3840         // The elapsed time induced by the start time below deliberately elides
3841         // the possible verification above.
3842         double sample_start_time_sec = os::elapsedTime();
3843 
3844         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3845 
3846         if (collector_state()->during_initial_mark_pause()) {
3847           concurrent_mark()->checkpointRootsInitialPre();
3848         }
3849 
3850         double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3851         g1_policy()->finalize_old_cset_part(time_remaining_ms);
3852 
3853         evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3854 
3855         // Make sure the remembered sets are up to date. This needs to be
3856         // done before register_humongous_regions_with_cset(), because the
3857         // remembered sets are used there to choose eager reclaim candidates.
3858         // If the remembered sets are not up to date we might miss some
3859         // entries that need to be handled.
3860         g1_rem_set()->cleanupHRRS();
3861 
3862         register_humongous_regions_with_cset();
3863 
3864         assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3865 
3866         _cm->note_start_of_gc();
3867         // We call this after finalize_cset() to
3868         // ensure that the CSet has been finalized.
3869         _cm->verify_no_cset_oops();
3870 
3871         if (_hr_printer.is_active()) {
3872           HeapRegion* hr = g1_policy()->collection_set();
3873           while (hr != NULL) {
3874             _hr_printer.cset(hr);
3875             hr = hr->next_in_collection_set();
3876           }
3877         }
3878 
3879 #ifdef ASSERT
3880         VerifyCSetClosure cl;
3881         collection_set_iterate(&cl);
3882 #endif // ASSERT
3883 
3884         // Initialize the GC alloc regions.
3885         _allocator->init_gc_alloc_regions(evacuation_info);
3886 
3887         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3888         pre_evacuate_collection_set();
3889 
3890         // Actually do the work...
3891         evacuate_collection_set(evacuation_info, &per_thread_states);
3892 
3893         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3894 
3895         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3896         free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3897 
3898         eagerly_reclaim_humongous_regions();
3899 
3900         g1_policy()->clear_collection_set();
3901 
3902         // Start a new incremental collection set for the next pause.
3903         g1_policy()->start_incremental_cset_building();
3904 
3905         clear_cset_fast_test();
3906 
3907         _young_list->reset_sampled_info();
3908 
3909         // Don't check the whole heap at this point as the
3910         // GC alloc regions from this pause have been tagged
3911         // as survivors and moved on to the survivor list.
3912         // Survivor regions will fail the !is_young() check.
3913         assert(check_young_list_empty(false /* check_heap */),
3914           "young list should be empty");
3915 
3916         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3917                                              _young_list->first_survivor_region(),
3918                                              _young_list->last_survivor_region());
3919 
3920         _young_list->reset_auxilary_lists();
3921 
3922         if (evacuation_failed()) {
3923           set_used(recalculate_used());
3924           if (_archive_allocator != NULL) {
3925             _archive_allocator->clear_used();
3926           }
3927           for (uint i = 0; i < ParallelGCThreads; i++) {
3928             if (_evacuation_failed_info_array[i].has_failed()) {
3929               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3930             }
3931           }
3932         } else {
3933           // The "used" of the the collection set have already been subtracted
3934           // when they were freed.  Add in the bytes evacuated.
3935           increase_used(g1_policy()->bytes_copied_during_gc());
3936         }
3937 
3938         if (collector_state()->during_initial_mark_pause()) {
3939           // We have to do this before we notify the CM threads that
3940           // they can start working to make sure that all the
3941           // appropriate initialization is done on the CM object.
3942           concurrent_mark()->checkpointRootsInitialPost();
3943           collector_state()->set_mark_in_progress(true);
3944           // Note that we don't actually trigger the CM thread at
3945           // this point. We do that later when we're sure that
3946           // the current thread has completed its logging output.
3947         }
3948 
3949         allocate_dummy_regions();
3950 
3951         _allocator->init_mutator_alloc_region();
3952 
3953         {
3954           size_t expand_bytes = g1_policy()->expansion_amount();
3955           if (expand_bytes > 0) {
3956             size_t bytes_before = capacity();
3957             // No need for an ergo verbose message here,
3958             // expansion_amount() does this when it returns a value > 0.
3959             double expand_ms;
3960             if (!expand(expand_bytes, &expand_ms)) {
3961               // We failed to expand the heap. Cannot do anything about it.
3962             }
3963             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3964           }
3965         }
3966 
3967         // We redo the verification but now wrt to the new CSet which
3968         // has just got initialized after the previous CSet was freed.
3969         _cm->verify_no_cset_oops();
3970         _cm->note_end_of_gc();
3971 
3972         // This timing is only used by the ergonomics to handle our pause target.
3973         // It is unclear why this should not include the full pause. We will
3974         // investigate this in CR 7178365.
3975         double sample_end_time_sec = os::elapsedTime();
3976         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3977         size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3978         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3979 
3980         evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3981         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3982 
3983         MemoryService::track_memory_usage();
3984 
3985         // In prepare_for_verify() below we'll need to scan the deferred
3986         // update buffers to bring the RSets up-to-date if
3987         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3988         // the update buffers we'll probably need to scan cards on the
3989         // regions we just allocated to (i.e., the GC alloc
3990         // regions). However, during the last GC we called
3991         // set_saved_mark() on all the GC alloc regions, so card
3992         // scanning might skip the [saved_mark_word()...top()] area of
3993         // those regions (i.e., the area we allocated objects into
3994         // during the last GC). But it shouldn't. Given that
3995         // saved_mark_word() is conditional on whether the GC time stamp
3996         // on the region is current or not, by incrementing the GC time
3997         // stamp here we invalidate all the GC time stamps on all the
3998         // regions and saved_mark_word() will simply return top() for
3999         // all the regions. This is a nicer way of ensuring this rather
4000         // than iterating over the regions and fixing them. In fact, the
4001         // GC time stamp increment here also ensures that
4002         // saved_mark_word() will return top() between pauses, i.e.,
4003         // during concurrent refinement. So we don't need the
4004         // is_gc_active() check to decided which top to use when
4005         // scanning cards (see CR 7039627).
4006         increment_gc_time_stamp();
4007 
4008         verify_after_gc();
4009         check_bitmaps("GC End");
4010 
4011         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4012         ref_processor_stw()->verify_no_references_recorded();
4013 
4014         // CM reference discovery will be re-enabled if necessary.
4015       }
4016 
4017       // We should do this after we potentially expand the heap so
4018       // that all the COMMIT events are generated before the end GC
4019       // event, and after we retire the GC alloc regions so that all
4020       // RETIRE events are generated before the end GC event.
4021       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4022 
4023 #ifdef TRACESPINNING
4024       ParallelTaskTerminator::print_termination_counts();
4025 #endif
4026 
4027       gc_epilogue(false);
4028     }
4029 
4030     // Print the remainder of the GC log output.
4031     log_gc_footer(os::elapsedTime() - pause_start_sec);
4032 
4033     // It is not yet to safe to tell the concurrent mark to
4034     // start as we have some optional output below. We don't want the
4035     // output from the concurrent mark thread interfering with this
4036     // logging output either.
4037 
4038     _hrm.verify_optional();
4039     verify_region_sets_optional();
4040 
4041     TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4042     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4043 
4044     print_heap_after_gc();
4045     trace_heap_after_gc(_gc_tracer_stw);
4046 
4047     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4048     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4049     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4050     // before any GC notifications are raised.
4051     g1mm()->update_sizes();
4052 
4053     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4054     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4055     _gc_timer_stw->register_gc_end();
4056     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4057   }
4058   // It should now be safe to tell the concurrent mark thread to start
4059   // without its logging output interfering with the logging output
4060   // that came from the pause.
4061 
4062   if (should_start_conc_mark) {
4063     // CAUTION: after the doConcurrentMark() call below,
4064     // the concurrent marking thread(s) could be running
4065     // concurrently with us. Make sure that anything after
4066     // this point does not assume that we are the only GC thread
4067     // running. Note: of course, the actual marking work will
4068     // not start until the safepoint itself is released in
4069     // SuspendibleThreadSet::desynchronize().
4070     doConcurrentMark();
4071   }
4072 
4073   return true;
4074 }
4075 
4076 void G1CollectedHeap::remove_self_forwarding_pointers() {
4077   double remove_self_forwards_start = os::elapsedTime();
4078 
4079   G1ParRemoveSelfForwardPtrsTask rsfp_task;
4080   workers()->run_task(&rsfp_task);
4081 
4082   // Now restore saved marks, if any.
4083   for (uint i = 0; i < ParallelGCThreads; i++) {
4084     OopAndMarkOopStack& cur = _preserved_objs[i];
4085     while (!cur.is_empty()) {
4086       OopAndMarkOop elem = cur.pop();
4087       elem.set_mark();
4088     }
4089     cur.clear(true);
4090   }
4091 
4092   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4093 }
4094 
4095 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4096   if (!_evacuation_failed) {
4097     _evacuation_failed = true;
4098   }
4099 
4100   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4101 
4102   // We want to call the "for_promotion_failure" version only in the
4103   // case of a promotion failure.
4104   if (m->must_be_preserved_for_promotion_failure(obj)) {
4105     OopAndMarkOop elem(obj, m);
4106     _preserved_objs[worker_id].push(elem);
4107   }
4108 }
4109 
4110 class G1ParEvacuateFollowersClosure : public VoidClosure {
4111 private:
4112   double _start_term;
4113   double _term_time;
4114   size_t _term_attempts;
4115 
4116   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4117   void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4118 protected:
4119   G1CollectedHeap*              _g1h;
4120   G1ParScanThreadState*         _par_scan_state;
4121   RefToScanQueueSet*            _queues;
4122   ParallelTaskTerminator*       _terminator;
4123 
4124   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4125   RefToScanQueueSet*      queues()         { return _queues; }
4126   ParallelTaskTerminator* terminator()     { return _terminator; }
4127 
4128 public:
4129   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4130                                 G1ParScanThreadState* par_scan_state,
4131                                 RefToScanQueueSet* queues,
4132                                 ParallelTaskTerminator* terminator)
4133     : _g1h(g1h), _par_scan_state(par_scan_state),
4134       _queues(queues), _terminator(terminator),
4135       _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4136 
4137   void do_void();
4138 
4139   double term_time() const { return _term_time; }
4140   size_t term_attempts() const { return _term_attempts; }
4141 
4142 private:
4143   inline bool offer_termination();
4144 };
4145 
4146 bool G1ParEvacuateFollowersClosure::offer_termination() {
4147   G1ParScanThreadState* const pss = par_scan_state();
4148   start_term_time();
4149   const bool res = terminator()->offer_termination();
4150   end_term_time();
4151   return res;
4152 }
4153 
4154 void G1ParEvacuateFollowersClosure::do_void() {
4155   G1ParScanThreadState* const pss = par_scan_state();
4156   pss->trim_queue();
4157   do {
4158     pss->steal_and_trim_queue(queues());
4159   } while (!offer_termination());
4160 }
4161 
4162 class G1ParTask : public AbstractGangTask {
4163 protected:
4164   G1CollectedHeap*         _g1h;
4165   G1ParScanThreadStateSet* _pss;
4166   RefToScanQueueSet*       _queues;
4167   G1RootProcessor*         _root_processor;
4168   ParallelTaskTerminator   _terminator;
4169   uint                     _n_workers;
4170 
4171 public:
4172   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4173     : AbstractGangTask("G1 collection"),
4174       _g1h(g1h),
4175       _pss(per_thread_states),
4176       _queues(task_queues),
4177       _root_processor(root_processor),
4178       _terminator(n_workers, _queues),
4179       _n_workers(n_workers)
4180   {}
4181 
4182   void work(uint worker_id) {
4183     if (worker_id >= _n_workers) return;  // no work needed this round
4184 
4185     double start_sec = os::elapsedTime();
4186     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4187 
4188     {
4189       ResourceMark rm;
4190       HandleMark   hm;
4191 
4192       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4193 
4194       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
4195       pss->set_ref_processor(rp);
4196 
4197       double start_strong_roots_sec = os::elapsedTime();
4198 
4199       _root_processor->evacuate_roots(pss->closures(), worker_id);
4200 
4201       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4202 
4203       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4204       // treating the nmethods visited to act as roots for concurrent marking.
4205       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4206       // objects copied by the current evacuation.
4207       size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4208                                                                              pss->closures()->weak_codeblobs(),
4209                                                                              worker_id);
4210 
4211       _pss->add_cards_scanned(worker_id, cards_scanned);
4212 
4213       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4214 
4215       double term_sec = 0.0;
4216       size_t evac_term_attempts = 0;
4217       {
4218         double start = os::elapsedTime();
4219         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4220         evac.do_void();
4221 
4222         evac_term_attempts = evac.term_attempts();
4223         term_sec = evac.term_time();
4224         double elapsed_sec = os::elapsedTime() - start;
4225         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4226         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4227         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4228       }
4229 
4230       assert(pss->queue_is_empty(), "should be empty");
4231 
4232       if (PrintTerminationStats) {
4233         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4234         size_t lab_waste;
4235         size_t lab_undo_waste;
4236         pss->waste(lab_waste, lab_undo_waste);
4237         _g1h->print_termination_stats(gclog_or_tty,
4238                                       worker_id,
4239                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
4240                                       strong_roots_sec * 1000.0,                  /* strong roots time */
4241                                       term_sec * 1000.0,                          /* evac term time */
4242                                       evac_term_attempts,                         /* evac term attempts */
4243                                       lab_waste,                                  /* alloc buffer waste */
4244                                       lab_undo_waste                              /* undo waste */
4245                                       );
4246       }
4247 
4248       // Close the inner scope so that the ResourceMark and HandleMark
4249       // destructors are executed here and are included as part of the
4250       // "GC Worker Time".
4251     }
4252     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4253   }
4254 };
4255 
4256 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4257   st->print_raw_cr("GC Termination Stats");
4258   st->print_raw_cr("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
4259   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts  total   alloc    undo");
4260   st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4261 }
4262 
4263 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4264                                               uint worker_id,
4265                                               double elapsed_ms,
4266                                               double strong_roots_ms,
4267                                               double term_ms,
4268                                               size_t term_attempts,
4269                                               size_t alloc_buffer_waste,
4270                                               size_t undo_waste) const {
4271   st->print_cr("%3d %9.2f %9.2f %6.2f "
4272                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4273                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4274                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4275                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4276                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4277                alloc_buffer_waste * HeapWordSize / K,
4278                undo_waste * HeapWordSize / K);
4279 }
4280 
4281 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4282 private:
4283   BoolObjectClosure* _is_alive;
4284   int _initial_string_table_size;
4285   int _initial_symbol_table_size;
4286 
4287   bool  _process_strings;
4288   int _strings_processed;
4289   int _strings_removed;
4290 
4291   bool  _process_symbols;
4292   int _symbols_processed;
4293   int _symbols_removed;
4294 
4295 public:
4296   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4297     AbstractGangTask("String/Symbol Unlinking"),
4298     _is_alive(is_alive),
4299     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4300     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4301 
4302     _initial_string_table_size = StringTable::the_table()->table_size();
4303     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4304     if (process_strings) {
4305       StringTable::clear_parallel_claimed_index();
4306     }
4307     if (process_symbols) {
4308       SymbolTable::clear_parallel_claimed_index();
4309     }
4310   }
4311 
4312   ~G1StringSymbolTableUnlinkTask() {
4313     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4314               "claim value %d after unlink less than initial string table size %d",
4315               StringTable::parallel_claimed_index(), _initial_string_table_size);
4316     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4317               "claim value %d after unlink less than initial symbol table size %d",
4318               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4319 
4320     if (G1TraceStringSymbolTableScrubbing) {
4321       gclog_or_tty->print_cr("Cleaned string and symbol table, "
4322                              "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4323                              "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4324                              strings_processed(), strings_removed(),
4325                              symbols_processed(), symbols_removed());
4326     }
4327   }
4328 
4329   void work(uint worker_id) {
4330     int strings_processed = 0;
4331     int strings_removed = 0;
4332     int symbols_processed = 0;
4333     int symbols_removed = 0;
4334     if (_process_strings) {
4335       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4336       Atomic::add(strings_processed, &_strings_processed);
4337       Atomic::add(strings_removed, &_strings_removed);
4338     }
4339     if (_process_symbols) {
4340       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4341       Atomic::add(symbols_processed, &_symbols_processed);
4342       Atomic::add(symbols_removed, &_symbols_removed);
4343     }
4344   }
4345 
4346   size_t strings_processed() const { return (size_t)_strings_processed; }
4347   size_t strings_removed()   const { return (size_t)_strings_removed; }
4348 
4349   size_t symbols_processed() const { return (size_t)_symbols_processed; }
4350   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
4351 };
4352 
4353 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4354 private:
4355   static Monitor* _lock;
4356 
4357   BoolObjectClosure* const _is_alive;
4358   const bool               _unloading_occurred;
4359   const uint               _num_workers;
4360 
4361   // Variables used to claim nmethods.
4362   nmethod* _first_nmethod;
4363   volatile nmethod* _claimed_nmethod;
4364 
4365   // The list of nmethods that need to be processed by the second pass.
4366   volatile nmethod* _postponed_list;
4367   volatile uint     _num_entered_barrier;
4368 
4369  public:
4370   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4371       _is_alive(is_alive),
4372       _unloading_occurred(unloading_occurred),
4373       _num_workers(num_workers),
4374       _first_nmethod(NULL),
4375       _claimed_nmethod(NULL),
4376       _postponed_list(NULL),
4377       _num_entered_barrier(0)
4378   {
4379     nmethod::increase_unloading_clock();
4380     // Get first alive nmethod
4381     NMethodIterator iter = NMethodIterator();
4382     if(iter.next_alive()) {
4383       _first_nmethod = iter.method();
4384     }
4385     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4386   }
4387 
4388   ~G1CodeCacheUnloadingTask() {
4389     CodeCache::verify_clean_inline_caches();
4390 
4391     CodeCache::set_needs_cache_clean(false);
4392     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4393 
4394     CodeCache::verify_icholder_relocations();
4395   }
4396 
4397  private:
4398   void add_to_postponed_list(nmethod* nm) {
4399       nmethod* old;
4400       do {
4401         old = (nmethod*)_postponed_list;
4402         nm->set_unloading_next(old);
4403       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4404   }
4405 
4406   void clean_nmethod(nmethod* nm) {
4407     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4408 
4409     if (postponed) {
4410       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4411       add_to_postponed_list(nm);
4412     }
4413 
4414     // Mark that this thread has been cleaned/unloaded.
4415     // After this call, it will be safe to ask if this nmethod was unloaded or not.
4416     nm->set_unloading_clock(nmethod::global_unloading_clock());
4417   }
4418 
4419   void clean_nmethod_postponed(nmethod* nm) {
4420     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4421   }
4422 
4423   static const int MaxClaimNmethods = 16;
4424 
4425   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4426     nmethod* first;
4427     NMethodIterator last;
4428 
4429     do {
4430       *num_claimed_nmethods = 0;
4431 
4432       first = (nmethod*)_claimed_nmethod;
4433       last = NMethodIterator(first);
4434 
4435       if (first != NULL) {
4436 
4437         for (int i = 0; i < MaxClaimNmethods; i++) {
4438           if (!last.next_alive()) {
4439             break;
4440           }
4441           claimed_nmethods[i] = last.method();
4442           (*num_claimed_nmethods)++;
4443         }
4444       }
4445 
4446     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4447   }
4448 
4449   nmethod* claim_postponed_nmethod() {
4450     nmethod* claim;
4451     nmethod* next;
4452 
4453     do {
4454       claim = (nmethod*)_postponed_list;
4455       if (claim == NULL) {
4456         return NULL;
4457       }
4458 
4459       next = claim->unloading_next();
4460 
4461     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4462 
4463     return claim;
4464   }
4465 
4466  public:
4467   // Mark that we're done with the first pass of nmethod cleaning.
4468   void barrier_mark(uint worker_id) {
4469     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4470     _num_entered_barrier++;
4471     if (_num_entered_barrier == _num_workers) {
4472       ml.notify_all();
4473     }
4474   }
4475 
4476   // See if we have to wait for the other workers to
4477   // finish their first-pass nmethod cleaning work.
4478   void barrier_wait(uint worker_id) {
4479     if (_num_entered_barrier < _num_workers) {
4480       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4481       while (_num_entered_barrier < _num_workers) {
4482           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4483       }
4484     }
4485   }
4486 
4487   // Cleaning and unloading of nmethods. Some work has to be postponed
4488   // to the second pass, when we know which nmethods survive.
4489   void work_first_pass(uint worker_id) {
4490     // The first nmethods is claimed by the first worker.
4491     if (worker_id == 0 && _first_nmethod != NULL) {
4492       clean_nmethod(_first_nmethod);
4493       _first_nmethod = NULL;
4494     }
4495 
4496     int num_claimed_nmethods;
4497     nmethod* claimed_nmethods[MaxClaimNmethods];
4498 
4499     while (true) {
4500       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4501 
4502       if (num_claimed_nmethods == 0) {
4503         break;
4504       }
4505 
4506       for (int i = 0; i < num_claimed_nmethods; i++) {
4507         clean_nmethod(claimed_nmethods[i]);
4508       }
4509     }
4510   }
4511 
4512   void work_second_pass(uint worker_id) {
4513     nmethod* nm;
4514     // Take care of postponed nmethods.
4515     while ((nm = claim_postponed_nmethod()) != NULL) {
4516       clean_nmethod_postponed(nm);
4517     }
4518   }
4519 };
4520 
4521 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4522 
4523 class G1KlassCleaningTask : public StackObj {
4524   BoolObjectClosure*                      _is_alive;
4525   volatile jint                           _clean_klass_tree_claimed;
4526   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4527 
4528  public:
4529   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4530       _is_alive(is_alive),
4531       _clean_klass_tree_claimed(0),
4532       _klass_iterator() {
4533   }
4534 
4535  private:
4536   bool claim_clean_klass_tree_task() {
4537     if (_clean_klass_tree_claimed) {
4538       return false;
4539     }
4540 
4541     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4542   }
4543 
4544   InstanceKlass* claim_next_klass() {
4545     Klass* klass;
4546     do {
4547       klass =_klass_iterator.next_klass();
4548     } while (klass != NULL && !klass->is_instance_klass());
4549 
4550     // this can be null so don't call InstanceKlass::cast
4551     return static_cast<InstanceKlass*>(klass);
4552   }
4553 
4554 public:
4555 
4556   void clean_klass(InstanceKlass* ik) {
4557     ik->clean_weak_instanceklass_links(_is_alive);
4558   }
4559 
4560   void work() {
4561     ResourceMark rm;
4562 
4563     // One worker will clean the subklass/sibling klass tree.
4564     if (claim_clean_klass_tree_task()) {
4565       Klass::clean_subklass_tree(_is_alive);
4566     }
4567 
4568     // All workers will help cleaning the classes,
4569     InstanceKlass* klass;
4570     while ((klass = claim_next_klass()) != NULL) {
4571       clean_klass(klass);
4572     }
4573   }
4574 };
4575 
4576 // To minimize the remark pause times, the tasks below are done in parallel.
4577 class G1ParallelCleaningTask : public AbstractGangTask {
4578 private:
4579   G1StringSymbolTableUnlinkTask _string_symbol_task;
4580   G1CodeCacheUnloadingTask      _code_cache_task;
4581   G1KlassCleaningTask           _klass_cleaning_task;
4582 
4583 public:
4584   // The constructor is run in the VMThread.
4585   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4586       AbstractGangTask("Parallel Cleaning"),
4587       _string_symbol_task(is_alive, process_strings, process_symbols),
4588       _code_cache_task(num_workers, is_alive, unloading_occurred),
4589       _klass_cleaning_task(is_alive) {
4590   }
4591 
4592   // The parallel work done by all worker threads.
4593   void work(uint worker_id) {
4594     // Do first pass of code cache cleaning.
4595     _code_cache_task.work_first_pass(worker_id);
4596 
4597     // Let the threads mark that the first pass is done.
4598     _code_cache_task.barrier_mark(worker_id);
4599 
4600     // Clean the Strings and Symbols.
4601     _string_symbol_task.work(worker_id);
4602 
4603     // Wait for all workers to finish the first code cache cleaning pass.
4604     _code_cache_task.barrier_wait(worker_id);
4605 
4606     // Do the second code cache cleaning work, which realize on
4607     // the liveness information gathered during the first pass.
4608     _code_cache_task.work_second_pass(worker_id);
4609 
4610     // Clean all klasses that were not unloaded.
4611     _klass_cleaning_task.work();
4612   }
4613 };
4614 
4615 
4616 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4617                                         bool process_strings,
4618                                         bool process_symbols,
4619                                         bool class_unloading_occurred) {
4620   uint n_workers = workers()->active_workers();
4621 
4622   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4623                                         n_workers, class_unloading_occurred);
4624   workers()->run_task(&g1_unlink_task);
4625 }
4626 
4627 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4628                                                      bool process_strings, bool process_symbols) {
4629   {
4630     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4631     workers()->run_task(&g1_unlink_task);
4632   }
4633 
4634   if (G1StringDedup::is_enabled()) {
4635     G1StringDedup::unlink(is_alive);
4636   }
4637 }
4638 
4639 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4640  private:
4641   DirtyCardQueueSet* _queue;
4642  public:
4643   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4644 
4645   virtual void work(uint worker_id) {
4646     G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4647     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4648 
4649     RedirtyLoggedCardTableEntryClosure cl;
4650     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4651 
4652     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4653   }
4654 };
4655 
4656 void G1CollectedHeap::redirty_logged_cards() {
4657   double redirty_logged_cards_start = os::elapsedTime();
4658 
4659   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4660   dirty_card_queue_set().reset_for_par_iteration();
4661   workers()->run_task(&redirty_task);
4662 
4663   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4664   dcq.merge_bufferlists(&dirty_card_queue_set());
4665   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4666 
4667   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4668 }
4669 
4670 // Weak Reference Processing support
4671 
4672 // An always "is_alive" closure that is used to preserve referents.
4673 // If the object is non-null then it's alive.  Used in the preservation
4674 // of referent objects that are pointed to by reference objects
4675 // discovered by the CM ref processor.
4676 class G1AlwaysAliveClosure: public BoolObjectClosure {
4677   G1CollectedHeap* _g1;
4678 public:
4679   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4680   bool do_object_b(oop p) {
4681     if (p != NULL) {
4682       return true;
4683     }
4684     return false;
4685   }
4686 };
4687 
4688 bool G1STWIsAliveClosure::do_object_b(oop p) {
4689   // An object is reachable if it is outside the collection set,
4690   // or is inside and copied.
4691   return !_g1->is_in_cset(p) || p->is_forwarded();
4692 }
4693 
4694 // Non Copying Keep Alive closure
4695 class G1KeepAliveClosure: public OopClosure {
4696   G1CollectedHeap* _g1;
4697 public:
4698   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4699   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4700   void do_oop(oop* p) {
4701     oop obj = *p;
4702     assert(obj != NULL, "the caller should have filtered out NULL values");
4703 
4704     const InCSetState cset_state = _g1->in_cset_state(obj);
4705     if (!cset_state.is_in_cset_or_humongous()) {
4706       return;
4707     }
4708     if (cset_state.is_in_cset()) {
4709       assert( obj->is_forwarded(), "invariant" );
4710       *p = obj->forwardee();
4711     } else {
4712       assert(!obj->is_forwarded(), "invariant" );
4713       assert(cset_state.is_humongous(),
4714              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4715       _g1->set_humongous_is_live(obj);
4716     }
4717   }
4718 };
4719 
4720 // Copying Keep Alive closure - can be called from both
4721 // serial and parallel code as long as different worker
4722 // threads utilize different G1ParScanThreadState instances
4723 // and different queues.
4724 
4725 class G1CopyingKeepAliveClosure: public OopClosure {
4726   G1CollectedHeap*         _g1h;
4727   OopClosure*              _copy_non_heap_obj_cl;
4728   G1ParScanThreadState*    _par_scan_state;
4729 
4730 public:
4731   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4732                             OopClosure* non_heap_obj_cl,
4733                             G1ParScanThreadState* pss):
4734     _g1h(g1h),
4735     _copy_non_heap_obj_cl(non_heap_obj_cl),
4736     _par_scan_state(pss)
4737   {}
4738 
4739   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4740   virtual void do_oop(      oop* p) { do_oop_work(p); }
4741 
4742   template <class T> void do_oop_work(T* p) {
4743     oop obj = oopDesc::load_decode_heap_oop(p);
4744 
4745     if (_g1h->is_in_cset_or_humongous(obj)) {
4746       // If the referent object has been forwarded (either copied
4747       // to a new location or to itself in the event of an
4748       // evacuation failure) then we need to update the reference
4749       // field and, if both reference and referent are in the G1
4750       // heap, update the RSet for the referent.
4751       //
4752       // If the referent has not been forwarded then we have to keep
4753       // it alive by policy. Therefore we have copy the referent.
4754       //
4755       // If the reference field is in the G1 heap then we can push
4756       // on the PSS queue. When the queue is drained (after each
4757       // phase of reference processing) the object and it's followers
4758       // will be copied, the reference field set to point to the
4759       // new location, and the RSet updated. Otherwise we need to
4760       // use the the non-heap or metadata closures directly to copy
4761       // the referent object and update the pointer, while avoiding
4762       // updating the RSet.
4763 
4764       if (_g1h->is_in_g1_reserved(p)) {
4765         _par_scan_state->push_on_queue(p);
4766       } else {
4767         assert(!Metaspace::contains((const void*)p),
4768                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4769         _copy_non_heap_obj_cl->do_oop(p);
4770       }
4771     }
4772   }
4773 };
4774 
4775 // Serial drain queue closure. Called as the 'complete_gc'
4776 // closure for each discovered list in some of the
4777 // reference processing phases.
4778 
4779 class G1STWDrainQueueClosure: public VoidClosure {
4780 protected:
4781   G1CollectedHeap* _g1h;
4782   G1ParScanThreadState* _par_scan_state;
4783 
4784   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4785 
4786 public:
4787   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4788     _g1h(g1h),
4789     _par_scan_state(pss)
4790   { }
4791 
4792   void do_void() {
4793     G1ParScanThreadState* const pss = par_scan_state();
4794     pss->trim_queue();
4795   }
4796 };
4797 
4798 // Parallel Reference Processing closures
4799 
4800 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4801 // processing during G1 evacuation pauses.
4802 
4803 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4804 private:
4805   G1CollectedHeap*          _g1h;
4806   G1ParScanThreadStateSet*  _pss;
4807   RefToScanQueueSet*        _queues;
4808   WorkGang*                 _workers;
4809   uint                      _active_workers;
4810 
4811 public:
4812   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4813                            G1ParScanThreadStateSet* per_thread_states,
4814                            WorkGang* workers,
4815                            RefToScanQueueSet *task_queues,
4816                            uint n_workers) :
4817     _g1h(g1h),
4818     _pss(per_thread_states),
4819     _queues(task_queues),
4820     _workers(workers),
4821     _active_workers(n_workers)
4822   {
4823     assert(n_workers > 0, "shouldn't call this otherwise");
4824   }
4825 
4826   // Executes the given task using concurrent marking worker threads.
4827   virtual void execute(ProcessTask& task);
4828   virtual void execute(EnqueueTask& task);
4829 };
4830 
4831 // Gang task for possibly parallel reference processing
4832 
4833 class G1STWRefProcTaskProxy: public AbstractGangTask {
4834   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4835   ProcessTask&     _proc_task;
4836   G1CollectedHeap* _g1h;
4837   G1ParScanThreadStateSet* _pss;
4838   RefToScanQueueSet* _task_queues;
4839   ParallelTaskTerminator* _terminator;
4840 
4841 public:
4842   G1STWRefProcTaskProxy(ProcessTask& proc_task,
4843                         G1CollectedHeap* g1h,
4844                         G1ParScanThreadStateSet* per_thread_states,
4845                         RefToScanQueueSet *task_queues,
4846                         ParallelTaskTerminator* terminator) :
4847     AbstractGangTask("Process reference objects in parallel"),
4848     _proc_task(proc_task),
4849     _g1h(g1h),
4850     _pss(per_thread_states),
4851     _task_queues(task_queues),
4852     _terminator(terminator)
4853   {}
4854 
4855   virtual void work(uint worker_id) {
4856     // The reference processing task executed by a single worker.
4857     ResourceMark rm;
4858     HandleMark   hm;
4859 
4860     G1STWIsAliveClosure is_alive(_g1h);
4861 
4862     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4863     pss->set_ref_processor(NULL);
4864 
4865     // Keep alive closure.
4866     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4867 
4868     // Complete GC closure
4869     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4870 
4871     // Call the reference processing task's work routine.
4872     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4873 
4874     // Note we cannot assert that the refs array is empty here as not all
4875     // of the processing tasks (specifically phase2 - pp2_work) execute
4876     // the complete_gc closure (which ordinarily would drain the queue) so
4877     // the queue may not be empty.
4878   }
4879 };
4880 
4881 // Driver routine for parallel reference processing.
4882 // Creates an instance of the ref processing gang
4883 // task and has the worker threads execute it.
4884 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4885   assert(_workers != NULL, "Need parallel worker threads.");
4886 
4887   ParallelTaskTerminator terminator(_active_workers, _queues);
4888   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4889 
4890   _workers->run_task(&proc_task_proxy);
4891 }
4892 
4893 // Gang task for parallel reference enqueueing.
4894 
4895 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4896   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4897   EnqueueTask& _enq_task;
4898 
4899 public:
4900   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4901     AbstractGangTask("Enqueue reference objects in parallel"),
4902     _enq_task(enq_task)
4903   { }
4904 
4905   virtual void work(uint worker_id) {
4906     _enq_task.work(worker_id);
4907   }
4908 };
4909 
4910 // Driver routine for parallel reference enqueueing.
4911 // Creates an instance of the ref enqueueing gang
4912 // task and has the worker threads execute it.
4913 
4914 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4915   assert(_workers != NULL, "Need parallel worker threads.");
4916 
4917   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4918 
4919   _workers->run_task(&enq_task_proxy);
4920 }
4921 
4922 // End of weak reference support closures
4923 
4924 // Abstract task used to preserve (i.e. copy) any referent objects
4925 // that are in the collection set and are pointed to by reference
4926 // objects discovered by the CM ref processor.
4927 
4928 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4929 protected:
4930   G1CollectedHeap*         _g1h;
4931   G1ParScanThreadStateSet* _pss;
4932   RefToScanQueueSet*       _queues;
4933   ParallelTaskTerminator   _terminator;
4934   uint                     _n_workers;
4935 
4936 public:
4937   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4938     AbstractGangTask("ParPreserveCMReferents"),
4939     _g1h(g1h),
4940     _pss(per_thread_states),
4941     _queues(task_queues),
4942     _terminator(workers, _queues),
4943     _n_workers(workers)
4944   { }
4945 
4946   void work(uint worker_id) {
4947     ResourceMark rm;
4948     HandleMark   hm;
4949 
4950     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4951     pss->set_ref_processor(NULL);
4952     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4953 
4954     // Is alive closure
4955     G1AlwaysAliveClosure always_alive(_g1h);
4956 
4957     // Copying keep alive closure. Applied to referent objects that need
4958     // to be copied.
4959     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4960 
4961     ReferenceProcessor* rp = _g1h->ref_processor_cm();
4962 
4963     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4964     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4965 
4966     // limit is set using max_num_q() - which was set using ParallelGCThreads.
4967     // So this must be true - but assert just in case someone decides to
4968     // change the worker ids.
4969     assert(worker_id < limit, "sanity");
4970     assert(!rp->discovery_is_atomic(), "check this code");
4971 
4972     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4973     for (uint idx = worker_id; idx < limit; idx += stride) {
4974       DiscoveredList& ref_list = rp->discovered_refs()[idx];
4975 
4976       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4977       while (iter.has_next()) {
4978         // Since discovery is not atomic for the CM ref processor, we
4979         // can see some null referent objects.
4980         iter.load_ptrs(DEBUG_ONLY(true));
4981         oop ref = iter.obj();
4982 
4983         // This will filter nulls.
4984         if (iter.is_referent_alive()) {
4985           iter.make_referent_alive();
4986         }
4987         iter.move_to_next();
4988       }
4989     }
4990 
4991     // Drain the queue - which may cause stealing
4992     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4993     drain_queue.do_void();
4994     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4995     assert(pss->queue_is_empty(), "should be");
4996   }
4997 };
4998 
4999 // Weak Reference processing during an evacuation pause (part 1).
5000 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5001   double ref_proc_start = os::elapsedTime();
5002 
5003   ReferenceProcessor* rp = _ref_processor_stw;
5004   assert(rp->discovery_enabled(), "should have been enabled");
5005 
5006   // Any reference objects, in the collection set, that were 'discovered'
5007   // by the CM ref processor should have already been copied (either by
5008   // applying the external root copy closure to the discovered lists, or
5009   // by following an RSet entry).
5010   //
5011   // But some of the referents, that are in the collection set, that these
5012   // reference objects point to may not have been copied: the STW ref
5013   // processor would have seen that the reference object had already
5014   // been 'discovered' and would have skipped discovering the reference,
5015   // but would not have treated the reference object as a regular oop.
5016   // As a result the copy closure would not have been applied to the
5017   // referent object.
5018   //
5019   // We need to explicitly copy these referent objects - the references
5020   // will be processed at the end of remarking.
5021   //
5022   // We also need to do this copying before we process the reference
5023   // objects discovered by the STW ref processor in case one of these
5024   // referents points to another object which is also referenced by an
5025   // object discovered by the STW ref processor.
5026 
5027   uint no_of_gc_workers = workers()->active_workers();
5028 
5029   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5030                                                  per_thread_states,
5031                                                  no_of_gc_workers,
5032                                                  _task_queues);
5033 
5034   workers()->run_task(&keep_cm_referents);
5035 
5036   // Closure to test whether a referent is alive.
5037   G1STWIsAliveClosure is_alive(this);
5038 
5039   // Even when parallel reference processing is enabled, the processing
5040   // of JNI refs is serial and performed serially by the current thread
5041   // rather than by a worker. The following PSS will be used for processing
5042   // JNI refs.
5043 
5044   // Use only a single queue for this PSS.
5045   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
5046   pss->set_ref_processor(NULL);
5047   assert(pss->queue_is_empty(), "pre-condition");
5048 
5049   // Keep alive closure.
5050   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5051 
5052   // Serial Complete GC closure
5053   G1STWDrainQueueClosure drain_queue(this, pss);
5054 
5055   // Setup the soft refs policy...
5056   rp->setup_policy(false);
5057 
5058   ReferenceProcessorStats stats;
5059   if (!rp->processing_is_mt()) {
5060     // Serial reference processing...
5061     stats = rp->process_discovered_references(&is_alive,
5062                                               &keep_alive,
5063                                               &drain_queue,
5064                                               NULL,
5065                                               _gc_timer_stw);
5066   } else {
5067     // Parallel reference processing
5068     assert(rp->num_q() == no_of_gc_workers, "sanity");
5069     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5070 
5071     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5072     stats = rp->process_discovered_references(&is_alive,
5073                                               &keep_alive,
5074                                               &drain_queue,
5075                                               &par_task_executor,
5076                                               _gc_timer_stw);
5077   }
5078 
5079   _gc_tracer_stw->report_gc_reference_stats(stats);
5080 
5081   // We have completed copying any necessary live referent objects.
5082   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5083 
5084   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5085   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5086 }
5087 
5088 // Weak Reference processing during an evacuation pause (part 2).
5089 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5090   double ref_enq_start = os::elapsedTime();
5091 
5092   ReferenceProcessor* rp = _ref_processor_stw;
5093   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5094 
5095   // Now enqueue any remaining on the discovered lists on to
5096   // the pending list.
5097   if (!rp->processing_is_mt()) {
5098     // Serial reference processing...
5099     rp->enqueue_discovered_references();
5100   } else {
5101     // Parallel reference enqueueing
5102 
5103     uint n_workers = workers()->active_workers();
5104 
5105     assert(rp->num_q() == n_workers, "sanity");
5106     assert(n_workers <= rp->max_num_q(), "sanity");
5107 
5108     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5109     rp->enqueue_discovered_references(&par_task_executor);
5110   }
5111 
5112   rp->verify_no_references_recorded();
5113   assert(!rp->discovery_enabled(), "should have been disabled");
5114 
5115   // FIXME
5116   // CM's reference processing also cleans up the string and symbol tables.
5117   // Should we do that here also? We could, but it is a serial operation
5118   // and could significantly increase the pause time.
5119 
5120   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5121   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5122 }
5123 
5124 void G1CollectedHeap::pre_evacuate_collection_set() {
5125   _expand_heap_after_alloc_failure = true;
5126   _evacuation_failed = false;
5127 
5128   // Disable the hot card cache.
5129   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5130   hot_card_cache->reset_hot_cache_claimed_index();
5131   hot_card_cache->set_use_cache(false);
5132 
5133 }
5134 
5135 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5136   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5137 
5138   // Should G1EvacuationFailureALot be in effect for this GC?
5139   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5140 
5141   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5142   double start_par_time_sec = os::elapsedTime();
5143   double end_par_time_sec;
5144 
5145   {
5146     const uint n_workers = workers()->active_workers();
5147     G1RootProcessor root_processor(this, n_workers);
5148     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5149     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5150     if (collector_state()->during_initial_mark_pause()) {
5151       ClassLoaderDataGraph::clear_claimed_marks();
5152     }
5153 
5154     // The individual threads will set their evac-failure closures.
5155     if (PrintTerminationStats) {
5156       print_termination_stats_hdr(gclog_or_tty);
5157     }
5158 
5159     workers()->run_task(&g1_par_task);
5160     end_par_time_sec = os::elapsedTime();
5161 
5162     // Closing the inner scope will execute the destructor
5163     // for the G1RootProcessor object. We record the current
5164     // elapsed time before closing the scope so that time
5165     // taken for the destructor is NOT included in the
5166     // reported parallel time.
5167   }
5168 
5169   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5170 
5171   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5172   phase_times->record_par_time(par_time_ms);
5173 
5174   double code_root_fixup_time_ms =
5175         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5176   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5177 
5178   // Process any discovered reference objects - we have
5179   // to do this _before_ we retire the GC alloc regions
5180   // as we may have to copy some 'reachable' referent
5181   // objects (and their reachable sub-graphs) that were
5182   // not copied during the pause.
5183   process_discovered_references(per_thread_states);
5184 
5185   if (G1StringDedup::is_enabled()) {
5186     double fixup_start = os::elapsedTime();
5187 
5188     G1STWIsAliveClosure is_alive(this);
5189     G1KeepAliveClosure keep_alive(this);
5190     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5191 
5192     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5193     phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5194   }
5195 
5196   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5197 
5198   if (evacuation_failed()) {
5199     remove_self_forwarding_pointers();
5200 
5201     // Reset the G1EvacuationFailureALot counters and flags
5202     // Note: the values are reset only when an actual
5203     // evacuation failure occurs.
5204     NOT_PRODUCT(reset_evacuation_should_fail();)
5205   }
5206 
5207   // Enqueue any remaining references remaining on the STW
5208   // reference processor's discovered lists. We need to do
5209   // this after the card table is cleaned (and verified) as
5210   // the act of enqueueing entries on to the pending list
5211   // will log these updates (and dirty their associated
5212   // cards). We need these updates logged to update any
5213   // RSets.
5214   enqueue_discovered_references(per_thread_states);
5215 }
5216 
5217 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5218   _allocator->release_gc_alloc_regions(evacuation_info);
5219 
5220   per_thread_states->flush();
5221 
5222   record_obj_copy_mem_stats();
5223 
5224   _survivor_evac_stats.adjust_desired_plab_sz();
5225   _old_evac_stats.adjust_desired_plab_sz();
5226 
5227   // Reset and re-enable the hot card cache.
5228   // Note the counts for the cards in the regions in the
5229   // collection set are reset when the collection set is freed.
5230   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5231   hot_card_cache->reset_hot_cache();
5232   hot_card_cache->set_use_cache(true);
5233 
5234   purge_code_root_memory();
5235 
5236   redirty_logged_cards();
5237 #if defined(COMPILER2) || INCLUDE_JVMCI
5238   DerivedPointerTable::update_pointers();
5239 #endif
5240 }
5241 
5242 void G1CollectedHeap::record_obj_copy_mem_stats() {
5243   g1_policy()->add_last_old_allocated_bytes(_old_evac_stats.allocated() * HeapWordSize);
5244 
5245   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5246                                                create_g1_evac_summary(&_old_evac_stats));
5247 }
5248 
5249 void G1CollectedHeap::free_region(HeapRegion* hr,
5250                                   FreeRegionList* free_list,
5251                                   bool par,
5252                                   bool locked) {
5253   assert(!hr->is_free(), "the region should not be free");
5254   assert(!hr->is_empty(), "the region should not be empty");
5255   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5256   assert(free_list != NULL, "pre-condition");
5257 
5258   if (G1VerifyBitmaps) {
5259     MemRegion mr(hr->bottom(), hr->end());
5260     concurrent_mark()->clearRangePrevBitmap(mr);
5261   }
5262 
5263   // Clear the card counts for this region.
5264   // Note: we only need to do this if the region is not young
5265   // (since we don't refine cards in young regions).
5266   if (!hr->is_young()) {
5267     _cg1r->hot_card_cache()->reset_card_counts(hr);
5268   }
5269   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5270   free_list->add_ordered(hr);
5271 }
5272 
5273 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5274                                             FreeRegionList* free_list,
5275                                             bool par) {
5276   assert(hr->is_humongous(), "this is only for humongous regions");
5277   assert(free_list != NULL, "pre-condition");
5278   hr->clear_humongous();
5279   free_region(hr, free_list, par);
5280 }
5281 
5282 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5283                                            const HeapRegionSetCount& humongous_regions_removed) {
5284   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5285     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5286     _old_set.bulk_remove(old_regions_removed);
5287     _humongous_set.bulk_remove(humongous_regions_removed);
5288   }
5289 
5290 }
5291 
5292 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5293   assert(list != NULL, "list can't be null");
5294   if (!list->is_empty()) {
5295     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5296     _hrm.insert_list_into_free_list(list);
5297   }
5298 }
5299 
5300 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5301   decrease_used(bytes);
5302 }
5303 
5304 class G1ParCleanupCTTask : public AbstractGangTask {
5305   G1SATBCardTableModRefBS* _ct_bs;
5306   G1CollectedHeap* _g1h;
5307   HeapRegion* volatile _su_head;
5308 public:
5309   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5310                      G1CollectedHeap* g1h) :
5311     AbstractGangTask("G1 Par Cleanup CT Task"),
5312     _ct_bs(ct_bs), _g1h(g1h) { }
5313 
5314   void work(uint worker_id) {
5315     HeapRegion* r;
5316     while (r = _g1h->pop_dirty_cards_region()) {
5317       clear_cards(r);
5318     }
5319   }
5320 
5321   void clear_cards(HeapRegion* r) {
5322     // Cards of the survivors should have already been dirtied.
5323     if (!r->is_survivor()) {
5324       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5325     }
5326   }
5327 };
5328 
5329 #ifndef PRODUCT
5330 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5331   G1CollectedHeap* _g1h;
5332   G1SATBCardTableModRefBS* _ct_bs;
5333 public:
5334   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5335     : _g1h(g1h), _ct_bs(ct_bs) { }
5336   virtual bool doHeapRegion(HeapRegion* r) {
5337     if (r->is_survivor()) {
5338       _g1h->verify_dirty_region(r);
5339     } else {
5340       _g1h->verify_not_dirty_region(r);
5341     }
5342     return false;
5343   }
5344 };
5345 
5346 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5347   // All of the region should be clean.
5348   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5349   MemRegion mr(hr->bottom(), hr->end());
5350   ct_bs->verify_not_dirty_region(mr);
5351 }
5352 
5353 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5354   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5355   // dirty allocated blocks as they allocate them. The thread that
5356   // retires each region and replaces it with a new one will do a
5357   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5358   // not dirty that area (one less thing to have to do while holding
5359   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5360   // is dirty.
5361   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5362   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5363   if (hr->is_young()) {
5364     ct_bs->verify_g1_young_region(mr);
5365   } else {
5366     ct_bs->verify_dirty_region(mr);
5367   }
5368 }
5369 
5370 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5371   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5372   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5373     verify_dirty_region(hr);
5374   }
5375 }
5376 
5377 void G1CollectedHeap::verify_dirty_young_regions() {
5378   verify_dirty_young_list(_young_list->first_region());
5379 }
5380 
5381 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5382                                                HeapWord* tams, HeapWord* end) {
5383   guarantee(tams <= end,
5384             "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5385   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5386   if (result < end) {
5387     gclog_or_tty->cr();
5388     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5389                            bitmap_name, p2i(result));
5390     gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5391                            bitmap_name, p2i(tams), p2i(end));
5392     return false;
5393   }
5394   return true;
5395 }
5396 
5397 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5398   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5399   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5400 
5401   HeapWord* bottom = hr->bottom();
5402   HeapWord* ptams  = hr->prev_top_at_mark_start();
5403   HeapWord* ntams  = hr->next_top_at_mark_start();
5404   HeapWord* end    = hr->end();
5405 
5406   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5407 
5408   bool res_n = true;
5409   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5410   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5411   // if we happen to be in that state.
5412   if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5413     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5414   }
5415   if (!res_p || !res_n) {
5416     gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5417                            HR_FORMAT_PARAMS(hr));
5418     gclog_or_tty->print_cr("#### Caller: %s", caller);
5419     return false;
5420   }
5421   return true;
5422 }
5423 
5424 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5425   if (!G1VerifyBitmaps) return;
5426 
5427   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5428 }
5429 
5430 class G1VerifyBitmapClosure : public HeapRegionClosure {
5431 private:
5432   const char* _caller;
5433   G1CollectedHeap* _g1h;
5434   bool _failures;
5435 
5436 public:
5437   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5438     _caller(caller), _g1h(g1h), _failures(false) { }
5439 
5440   bool failures() { return _failures; }
5441 
5442   virtual bool doHeapRegion(HeapRegion* hr) {
5443     bool result = _g1h->verify_bitmaps(_caller, hr);
5444     if (!result) {
5445       _failures = true;
5446     }
5447     return false;
5448   }
5449 };
5450 
5451 void G1CollectedHeap::check_bitmaps(const char* caller) {
5452   if (!G1VerifyBitmaps) return;
5453 
5454   G1VerifyBitmapClosure cl(caller, this);
5455   heap_region_iterate(&cl);
5456   guarantee(!cl.failures(), "bitmap verification");
5457 }
5458 
5459 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5460  private:
5461   bool _failures;
5462  public:
5463   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5464 
5465   virtual bool doHeapRegion(HeapRegion* hr) {
5466     uint i = hr->hrm_index();
5467     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5468     if (hr->is_humongous()) {
5469       if (hr->in_collection_set()) {
5470         gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5471         _failures = true;
5472         return true;
5473       }
5474       if (cset_state.is_in_cset()) {
5475         gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5476         _failures = true;
5477         return true;
5478       }
5479       if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5480         gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5481         _failures = true;
5482         return true;
5483       }
5484     } else {
5485       if (cset_state.is_humongous()) {
5486         gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5487         _failures = true;
5488         return true;
5489       }
5490       if (hr->in_collection_set() != cset_state.is_in_cset()) {
5491         gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5492                                hr->in_collection_set(), cset_state.value(), i);
5493         _failures = true;
5494         return true;
5495       }
5496       if (cset_state.is_in_cset()) {
5497         if (hr->is_young() != (cset_state.is_young())) {
5498           gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5499                                  hr->is_young(), cset_state.value(), i);
5500           _failures = true;
5501           return true;
5502         }
5503         if (hr->is_old() != (cset_state.is_old())) {
5504           gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5505                                  hr->is_old(), cset_state.value(), i);
5506           _failures = true;
5507           return true;
5508         }
5509       }
5510     }
5511     return false;
5512   }
5513 
5514   bool failures() const { return _failures; }
5515 };
5516 
5517 bool G1CollectedHeap::check_cset_fast_test() {
5518   G1CheckCSetFastTableClosure cl;
5519   _hrm.iterate(&cl);
5520   return !cl.failures();
5521 }
5522 #endif // PRODUCT
5523 
5524 void G1CollectedHeap::cleanUpCardTable() {
5525   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5526   double start = os::elapsedTime();
5527 
5528   {
5529     // Iterate over the dirty cards region list.
5530     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5531 
5532     workers()->run_task(&cleanup_task);
5533 #ifndef PRODUCT
5534     if (G1VerifyCTCleanup || VerifyAfterGC) {
5535       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5536       heap_region_iterate(&cleanup_verifier);
5537     }
5538 #endif
5539   }
5540 
5541   double elapsed = os::elapsedTime() - start;
5542   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5543 }
5544 
5545 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5546   size_t pre_used = 0;
5547   FreeRegionList local_free_list("Local List for CSet Freeing");
5548 
5549   double young_time_ms     = 0.0;
5550   double non_young_time_ms = 0.0;
5551 
5552   // Since the collection set is a superset of the the young list,
5553   // all we need to do to clear the young list is clear its
5554   // head and length, and unlink any young regions in the code below
5555   _young_list->clear();
5556 
5557   G1CollectorPolicy* policy = g1_policy();
5558 
5559   double start_sec = os::elapsedTime();
5560   bool non_young = true;
5561 
5562   HeapRegion* cur = cs_head;
5563   int age_bound = -1;
5564   size_t rs_lengths = 0;
5565 
5566   while (cur != NULL) {
5567     assert(!is_on_master_free_list(cur), "sanity");
5568     if (non_young) {
5569       if (cur->is_young()) {
5570         double end_sec = os::elapsedTime();
5571         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5572         non_young_time_ms += elapsed_ms;
5573 
5574         start_sec = os::elapsedTime();
5575         non_young = false;
5576       }
5577     } else {
5578       if (!cur->is_young()) {
5579         double end_sec = os::elapsedTime();
5580         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5581         young_time_ms += elapsed_ms;
5582 
5583         start_sec = os::elapsedTime();
5584         non_young = true;
5585       }
5586     }
5587 
5588     rs_lengths += cur->rem_set()->occupied_locked();
5589 
5590     HeapRegion* next = cur->next_in_collection_set();
5591     assert(cur->in_collection_set(), "bad CS");
5592     cur->set_next_in_collection_set(NULL);
5593     clear_in_cset(cur);
5594 
5595     if (cur->is_young()) {
5596       int index = cur->young_index_in_cset();
5597       assert(index != -1, "invariant");
5598       assert((uint) index < policy->young_cset_region_length(), "invariant");
5599       size_t words_survived = surviving_young_words[index];
5600       cur->record_surv_words_in_group(words_survived);
5601 
5602       // At this point the we have 'popped' cur from the collection set
5603       // (linked via next_in_collection_set()) but it is still in the
5604       // young list (linked via next_young_region()). Clear the
5605       // _next_young_region field.
5606       cur->set_next_young_region(NULL);
5607     } else {
5608       int index = cur->young_index_in_cset();
5609       assert(index == -1, "invariant");
5610     }
5611 
5612     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5613             (!cur->is_young() && cur->young_index_in_cset() == -1),
5614             "invariant" );
5615 
5616     if (!cur->evacuation_failed()) {
5617       MemRegion used_mr = cur->used_region();
5618 
5619       // And the region is empty.
5620       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5621       pre_used += cur->used();
5622       free_region(cur, &local_free_list, false /* par */, true /* locked */);
5623     } else {
5624       cur->uninstall_surv_rate_group();
5625       if (cur->is_young()) {
5626         cur->set_young_index_in_cset(-1);
5627       }
5628       cur->set_evacuation_failed(false);
5629       // When moving a young gen region to old gen, we "allocate" that whole region
5630       // there. This is in addition to any already evacuated objects. Notify the
5631       // policy about that.
5632       // Old gen regions do not cause an additional allocation: both the objects
5633       // still in the region and the ones already moved are accounted for elsewhere.
5634       if (cur->is_young()) {
5635         policy->add_last_old_allocated_bytes(HeapRegion::GrainBytes);
5636       }
5637       // The region is now considered to be old.
5638       cur->set_old();
5639       // Do some allocation statistics accounting. Regions that failed evacuation
5640       // are always made old, so there is no need to update anything in the young
5641       // gen statistics, but we need to update old gen statistics.
5642       size_t used_words = cur->marked_bytes() / HeapWordSize;
5643       _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5644       _old_set.add(cur);
5645       evacuation_info.increment_collectionset_used_after(cur->used());
5646     }
5647     cur = next;
5648   }
5649 
5650   evacuation_info.set_regions_freed(local_free_list.length());
5651   policy->record_max_rs_lengths(rs_lengths);
5652   policy->cset_regions_freed();
5653 
5654   double end_sec = os::elapsedTime();
5655   double elapsed_ms = (end_sec - start_sec) * 1000.0;
5656 
5657   if (non_young) {
5658     non_young_time_ms += elapsed_ms;
5659   } else {
5660     young_time_ms += elapsed_ms;
5661   }
5662 
5663   prepend_to_freelist(&local_free_list);
5664   decrement_summary_bytes(pre_used);
5665   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5666   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5667 }
5668 
5669 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5670  private:
5671   FreeRegionList* _free_region_list;
5672   HeapRegionSet* _proxy_set;
5673   HeapRegionSetCount _humongous_regions_removed;
5674   size_t _freed_bytes;
5675  public:
5676 
5677   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5678     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5679   }
5680 
5681   virtual bool doHeapRegion(HeapRegion* r) {
5682     if (!r->is_starts_humongous()) {
5683       return false;
5684     }
5685 
5686     G1CollectedHeap* g1h = G1CollectedHeap::heap();
5687 
5688     oop obj = (oop)r->bottom();
5689     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5690 
5691     // The following checks whether the humongous object is live are sufficient.
5692     // The main additional check (in addition to having a reference from the roots
5693     // or the young gen) is whether the humongous object has a remembered set entry.
5694     //
5695     // A humongous object cannot be live if there is no remembered set for it
5696     // because:
5697     // - there can be no references from within humongous starts regions referencing
5698     // the object because we never allocate other objects into them.
5699     // (I.e. there are no intra-region references that may be missed by the
5700     // remembered set)
5701     // - as soon there is a remembered set entry to the humongous starts region
5702     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5703     // until the end of a concurrent mark.
5704     //
5705     // It is not required to check whether the object has been found dead by marking
5706     // or not, in fact it would prevent reclamation within a concurrent cycle, as
5707     // all objects allocated during that time are considered live.
5708     // SATB marking is even more conservative than the remembered set.
5709     // So if at this point in the collection there is no remembered set entry,
5710     // nobody has a reference to it.
5711     // At the start of collection we flush all refinement logs, and remembered sets
5712     // are completely up-to-date wrt to references to the humongous object.
5713     //
5714     // Other implementation considerations:
5715     // - never consider object arrays at this time because they would pose
5716     // considerable effort for cleaning up the the remembered sets. This is
5717     // required because stale remembered sets might reference locations that
5718     // are currently allocated into.
5719     uint region_idx = r->hrm_index();
5720     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5721         !r->rem_set()->is_empty()) {
5722 
5723       if (G1TraceEagerReclaimHumongousObjects) {
5724         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",
5725                                region_idx,
5726                                (size_t)obj->size() * HeapWordSize,
5727                                p2i(r->bottom()),
5728                                r->rem_set()->occupied(),
5729                                r->rem_set()->strong_code_roots_list_length(),
5730                                next_bitmap->isMarked(r->bottom()),
5731                                g1h->is_humongous_reclaim_candidate(region_idx),
5732                                obj->is_typeArray()
5733                               );
5734       }
5735 
5736       return false;
5737     }
5738 
5739     guarantee(obj->is_typeArray(),
5740               "Only eagerly reclaiming type arrays is supported, but the object "
5741               PTR_FORMAT " is not.", p2i(r->bottom()));
5742 
5743     if (G1TraceEagerReclaimHumongousObjects) {
5744       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",
5745                              region_idx,
5746                              (size_t)obj->size() * HeapWordSize,
5747                              p2i(r->bottom()),
5748                              r->rem_set()->occupied(),
5749                              r->rem_set()->strong_code_roots_list_length(),
5750                              next_bitmap->isMarked(r->bottom()),
5751                              g1h->is_humongous_reclaim_candidate(region_idx),
5752                              obj->is_typeArray()
5753                             );
5754     }
5755     // Need to clear mark bit of the humongous object if already set.
5756     if (next_bitmap->isMarked(r->bottom())) {
5757       next_bitmap->clear(r->bottom());
5758     }
5759     do {
5760       HeapRegion* next = g1h->next_region_in_humongous(r);
5761       _freed_bytes += r->used();
5762       r->set_containing_set(NULL);
5763       _humongous_regions_removed.increment(1u, r->capacity());
5764       g1h->free_humongous_region(r, _free_region_list, false);
5765       r = next;
5766     } while (r != NULL);
5767 
5768     return false;
5769   }
5770 
5771   HeapRegionSetCount& humongous_free_count() {
5772     return _humongous_regions_removed;
5773   }
5774 
5775   size_t bytes_freed() const {
5776     return _freed_bytes;
5777   }
5778 
5779   size_t humongous_reclaimed() const {
5780     return _humongous_regions_removed.length();
5781   }
5782 };
5783 
5784 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5785   assert_at_safepoint(true);
5786 
5787   if (!G1EagerReclaimHumongousObjects ||
5788       (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5789     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5790     return;
5791   }
5792 
5793   double start_time = os::elapsedTime();
5794 
5795   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5796 
5797   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5798   heap_region_iterate(&cl);
5799 
5800   HeapRegionSetCount empty_set;
5801   remove_from_old_sets(empty_set, cl.humongous_free_count());
5802 
5803   G1HRPrinter* hrp = hr_printer();
5804   if (hrp->is_active()) {
5805     FreeRegionListIterator iter(&local_cleanup_list);
5806     while (iter.more_available()) {
5807       HeapRegion* hr = iter.get_next();
5808       hrp->cleanup(hr);
5809     }
5810   }
5811 
5812   prepend_to_freelist(&local_cleanup_list);
5813   decrement_summary_bytes(cl.bytes_freed());
5814 
5815   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5816                                                                     cl.humongous_reclaimed());
5817 }
5818 
5819 // This routine is similar to the above but does not record
5820 // any policy statistics or update free lists; we are abandoning
5821 // the current incremental collection set in preparation of a
5822 // full collection. After the full GC we will start to build up
5823 // the incremental collection set again.
5824 // This is only called when we're doing a full collection
5825 // and is immediately followed by the tearing down of the young list.
5826 
5827 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5828   HeapRegion* cur = cs_head;
5829 
5830   while (cur != NULL) {
5831     HeapRegion* next = cur->next_in_collection_set();
5832     assert(cur->in_collection_set(), "bad CS");
5833     cur->set_next_in_collection_set(NULL);
5834     clear_in_cset(cur);
5835     cur->set_young_index_in_cset(-1);
5836     cur = next;
5837   }
5838 }
5839 
5840 void G1CollectedHeap::set_free_regions_coming() {
5841   if (G1ConcRegionFreeingVerbose) {
5842     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5843                            "setting free regions coming");
5844   }
5845 
5846   assert(!free_regions_coming(), "pre-condition");
5847   _free_regions_coming = true;
5848 }
5849 
5850 void G1CollectedHeap::reset_free_regions_coming() {
5851   assert(free_regions_coming(), "pre-condition");
5852 
5853   {
5854     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5855     _free_regions_coming = false;
5856     SecondaryFreeList_lock->notify_all();
5857   }
5858 
5859   if (G1ConcRegionFreeingVerbose) {
5860     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5861                            "reset free regions coming");
5862   }
5863 }
5864 
5865 void G1CollectedHeap::wait_while_free_regions_coming() {
5866   // Most of the time we won't have to wait, so let's do a quick test
5867   // first before we take the lock.
5868   if (!free_regions_coming()) {
5869     return;
5870   }
5871 
5872   if (G1ConcRegionFreeingVerbose) {
5873     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5874                            "waiting for free regions");
5875   }
5876 
5877   {
5878     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5879     while (free_regions_coming()) {
5880       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5881     }
5882   }
5883 
5884   if (G1ConcRegionFreeingVerbose) {
5885     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5886                            "done waiting for free regions");
5887   }
5888 }
5889 
5890 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5891   return _allocator->is_retained_old_region(hr);
5892 }
5893 
5894 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5895   _young_list->push_region(hr);
5896 }
5897 
5898 class NoYoungRegionsClosure: public HeapRegionClosure {
5899 private:
5900   bool _success;
5901 public:
5902   NoYoungRegionsClosure() : _success(true) { }
5903   bool doHeapRegion(HeapRegion* r) {
5904     if (r->is_young()) {
5905       gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5906                              p2i(r->bottom()), p2i(r->end()));
5907       _success = false;
5908     }
5909     return false;
5910   }
5911   bool success() { return _success; }
5912 };
5913 
5914 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5915   bool ret = _young_list->check_list_empty(check_sample);
5916 
5917   if (check_heap) {
5918     NoYoungRegionsClosure closure;
5919     heap_region_iterate(&closure);
5920     ret = ret && closure.success();
5921   }
5922 
5923   return ret;
5924 }
5925 
5926 class TearDownRegionSetsClosure : public HeapRegionClosure {
5927 private:
5928   HeapRegionSet *_old_set;
5929 
5930 public:
5931   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5932 
5933   bool doHeapRegion(HeapRegion* r) {
5934     if (r->is_old()) {
5935       _old_set->remove(r);
5936     } else {
5937       // We ignore free regions, we'll empty the free list afterwards.
5938       // We ignore young regions, we'll empty the young list afterwards.
5939       // We ignore humongous regions, we're not tearing down the
5940       // humongous regions set.
5941       assert(r->is_free() || r->is_young() || r->is_humongous(),
5942              "it cannot be another type");
5943     }
5944     return false;
5945   }
5946 
5947   ~TearDownRegionSetsClosure() {
5948     assert(_old_set->is_empty(), "post-condition");
5949   }
5950 };
5951 
5952 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5953   assert_at_safepoint(true /* should_be_vm_thread */);
5954 
5955   if (!free_list_only) {
5956     TearDownRegionSetsClosure cl(&_old_set);
5957     heap_region_iterate(&cl);
5958 
5959     // Note that emptying the _young_list is postponed and instead done as
5960     // the first step when rebuilding the regions sets again. The reason for
5961     // this is that during a full GC string deduplication needs to know if
5962     // a collected region was young or old when the full GC was initiated.
5963   }
5964   _hrm.remove_all_free_regions();
5965 }
5966 
5967 void G1CollectedHeap::increase_used(size_t bytes) {
5968   _summary_bytes_used += bytes;
5969 }
5970 
5971 void G1CollectedHeap::decrease_used(size_t bytes) {
5972   assert(_summary_bytes_used >= bytes,
5973          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5974          _summary_bytes_used, bytes);
5975   _summary_bytes_used -= bytes;
5976 }
5977 
5978 void G1CollectedHeap::set_used(size_t bytes) {
5979   _summary_bytes_used = bytes;
5980 }
5981 
5982 class RebuildRegionSetsClosure : public HeapRegionClosure {
5983 private:
5984   bool            _free_list_only;
5985   HeapRegionSet*   _old_set;
5986   HeapRegionManager*   _hrm;
5987   size_t          _total_used;
5988 
5989 public:
5990   RebuildRegionSetsClosure(bool free_list_only,
5991                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
5992     _free_list_only(free_list_only),
5993     _old_set(old_set), _hrm(hrm), _total_used(0) {
5994     assert(_hrm->num_free_regions() == 0, "pre-condition");
5995     if (!free_list_only) {
5996       assert(_old_set->is_empty(), "pre-condition");
5997     }
5998   }
5999 
6000   bool doHeapRegion(HeapRegion* r) {
6001     if (r->is_empty()) {
6002       // Add free regions to the free list
6003       r->set_free();
6004       r->set_allocation_context(AllocationContext::system());
6005       _hrm->insert_into_free_list(r);
6006     } else if (!_free_list_only) {
6007       assert(!r->is_young(), "we should not come across young regions");
6008 
6009       if (r->is_humongous()) {
6010         // We ignore humongous regions. We left the humongous set unchanged.
6011       } else {
6012         // Objects that were compacted would have ended up on regions
6013         // that were previously old or free.  Archive regions (which are
6014         // old) will not have been touched.
6015         assert(r->is_free() || r->is_old(), "invariant");
6016         // We now consider them old, so register as such. Leave
6017         // archive regions set that way, however, while still adding
6018         // them to the old set.
6019         if (!r->is_archive()) {
6020           r->set_old();
6021         }
6022         _old_set->add(r);
6023       }
6024       _total_used += r->used();
6025     }
6026 
6027     return false;
6028   }
6029 
6030   size_t total_used() {
6031     return _total_used;
6032   }
6033 };
6034 
6035 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6036   assert_at_safepoint(true /* should_be_vm_thread */);
6037 
6038   if (!free_list_only) {
6039     _young_list->empty_list();
6040   }
6041 
6042   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6043   heap_region_iterate(&cl);
6044 
6045   if (!free_list_only) {
6046     set_used(cl.total_used());
6047     if (_archive_allocator != NULL) {
6048       _archive_allocator->clear_used();
6049     }
6050   }
6051   assert(used_unlocked() == recalculate_used(),
6052          "inconsistent used_unlocked(), "
6053          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6054          used_unlocked(), recalculate_used());
6055 }
6056 
6057 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6058   _refine_cte_cl->set_concurrent(concurrent);
6059 }
6060 
6061 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6062   HeapRegion* hr = heap_region_containing(p);
6063   return hr->is_in(p);
6064 }
6065 
6066 // Methods for the mutator alloc region
6067 
6068 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6069                                                       bool force) {
6070   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6071   assert(!force || g1_policy()->can_expand_young_list(),
6072          "if force is true we should be able to expand the young list");
6073   bool young_list_full = g1_policy()->is_young_list_full();
6074   if (force || !young_list_full) {
6075     HeapRegion* new_alloc_region = new_region(word_size,
6076                                               false /* is_old */,
6077                                               false /* do_expand */);
6078     if (new_alloc_region != NULL) {
6079       set_region_short_lived_locked(new_alloc_region);
6080       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6081       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6082       return new_alloc_region;
6083     }
6084   }
6085   return NULL;
6086 }
6087 
6088 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6089                                                   size_t allocated_bytes) {
6090   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6091   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6092 
6093   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6094   increase_used(allocated_bytes);
6095   _hr_printer.retire(alloc_region);
6096   // We update the eden sizes here, when the region is retired,
6097   // instead of when it's allocated, since this is the point that its
6098   // used space has been recored in _summary_bytes_used.
6099   g1mm()->update_eden_size();
6100 }
6101 
6102 // Methods for the GC alloc regions
6103 
6104 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6105                                                  uint count,
6106                                                  InCSetState dest) {
6107   assert(FreeList_lock->owned_by_self(), "pre-condition");
6108 
6109   if (count < g1_policy()->max_regions(dest)) {
6110     const bool is_survivor = (dest.is_young());
6111     HeapRegion* new_alloc_region = new_region(word_size,
6112                                               !is_survivor,
6113                                               true /* do_expand */);
6114     if (new_alloc_region != NULL) {
6115       // We really only need to do this for old regions given that we
6116       // should never scan survivors. But it doesn't hurt to do it
6117       // for survivors too.
6118       new_alloc_region->record_timestamp();
6119       if (is_survivor) {
6120         new_alloc_region->set_survivor();
6121         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6122         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6123       } else {
6124         new_alloc_region->set_old();
6125         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6126         check_bitmaps("Old Region Allocation", new_alloc_region);
6127       }
6128       bool during_im = collector_state()->during_initial_mark_pause();
6129       new_alloc_region->note_start_of_copying(during_im);
6130       return new_alloc_region;
6131     }
6132   }
6133   return NULL;
6134 }
6135 
6136 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6137                                              size_t allocated_bytes,
6138                                              InCSetState dest) {
6139   bool during_im = collector_state()->during_initial_mark_pause();
6140   alloc_region->note_end_of_copying(during_im);
6141   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6142   if (dest.is_young()) {
6143     young_list()->add_survivor_region(alloc_region);
6144   } else {
6145     _old_set.add(alloc_region);
6146   }
6147   _hr_printer.retire(alloc_region);
6148 }
6149 
6150 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6151   bool expanded = false;
6152   uint index = _hrm.find_highest_free(&expanded);
6153 
6154   if (index != G1_NO_HRM_INDEX) {
6155     if (expanded) {
6156       ergo_verbose1(ErgoHeapSizing,
6157                     "attempt heap expansion",
6158                     ergo_format_reason("requested address range outside heap bounds")
6159                     ergo_format_byte("region size"),
6160                     HeapRegion::GrainWords * HeapWordSize);
6161     }
6162     _hrm.allocate_free_regions_starting_at(index, 1);
6163     return region_at(index);
6164   }
6165   return NULL;
6166 }
6167 
6168 // Heap region set verification
6169 
6170 class VerifyRegionListsClosure : public HeapRegionClosure {
6171 private:
6172   HeapRegionSet*   _old_set;
6173   HeapRegionSet*   _humongous_set;
6174   HeapRegionManager*   _hrm;
6175 
6176 public:
6177   HeapRegionSetCount _old_count;
6178   HeapRegionSetCount _humongous_count;
6179   HeapRegionSetCount _free_count;
6180 
6181   VerifyRegionListsClosure(HeapRegionSet* old_set,
6182                            HeapRegionSet* humongous_set,
6183                            HeapRegionManager* hrm) :
6184     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6185     _old_count(), _humongous_count(), _free_count(){ }
6186 
6187   bool doHeapRegion(HeapRegion* hr) {
6188     if (hr->is_young()) {
6189       // TODO
6190     } else if (hr->is_humongous()) {
6191       assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6192       _humongous_count.increment(1u, hr->capacity());
6193     } else if (hr->is_empty()) {
6194       assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6195       _free_count.increment(1u, hr->capacity());
6196     } else if (hr->is_old()) {
6197       assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6198       _old_count.increment(1u, hr->capacity());
6199     } else {
6200       // There are no other valid region types. Check for one invalid
6201       // one we can identify: pinned without old or humongous set.
6202       assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6203       ShouldNotReachHere();
6204     }
6205     return false;
6206   }
6207 
6208   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6209     guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6210     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6211               old_set->total_capacity_bytes(), _old_count.capacity());
6212 
6213     guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6214     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6215               humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6216 
6217     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());
6218     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6219               free_list->total_capacity_bytes(), _free_count.capacity());
6220   }
6221 };
6222 
6223 void G1CollectedHeap::verify_region_sets() {
6224   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6225 
6226   // First, check the explicit lists.
6227   _hrm.verify();
6228   {
6229     // Given that a concurrent operation might be adding regions to
6230     // the secondary free list we have to take the lock before
6231     // verifying it.
6232     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6233     _secondary_free_list.verify_list();
6234   }
6235 
6236   // If a concurrent region freeing operation is in progress it will
6237   // be difficult to correctly attributed any free regions we come
6238   // across to the correct free list given that they might belong to
6239   // one of several (free_list, secondary_free_list, any local lists,
6240   // etc.). So, if that's the case we will skip the rest of the
6241   // verification operation. Alternatively, waiting for the concurrent
6242   // operation to complete will have a non-trivial effect on the GC's
6243   // operation (no concurrent operation will last longer than the
6244   // interval between two calls to verification) and it might hide
6245   // any issues that we would like to catch during testing.
6246   if (free_regions_coming()) {
6247     return;
6248   }
6249 
6250   // Make sure we append the secondary_free_list on the free_list so
6251   // that all free regions we will come across can be safely
6252   // attributed to the free_list.
6253   append_secondary_free_list_if_not_empty_with_lock();
6254 
6255   // Finally, make sure that the region accounting in the lists is
6256   // consistent with what we see in the heap.
6257 
6258   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6259   heap_region_iterate(&cl);
6260   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6261 }
6262 
6263 // Optimized nmethod scanning
6264 
6265 class RegisterNMethodOopClosure: public OopClosure {
6266   G1CollectedHeap* _g1h;
6267   nmethod* _nm;
6268 
6269   template <class T> void do_oop_work(T* p) {
6270     T heap_oop = oopDesc::load_heap_oop(p);
6271     if (!oopDesc::is_null(heap_oop)) {
6272       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6273       HeapRegion* hr = _g1h->heap_region_containing(obj);
6274       assert(!hr->is_continues_humongous(),
6275              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6276              " starting at " HR_FORMAT,
6277              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6278 
6279       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6280       hr->add_strong_code_root_locked(_nm);
6281     }
6282   }
6283 
6284 public:
6285   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6286     _g1h(g1h), _nm(nm) {}
6287 
6288   void do_oop(oop* p)       { do_oop_work(p); }
6289   void do_oop(narrowOop* p) { do_oop_work(p); }
6290 };
6291 
6292 class UnregisterNMethodOopClosure: public OopClosure {
6293   G1CollectedHeap* _g1h;
6294   nmethod* _nm;
6295 
6296   template <class T> void do_oop_work(T* p) {
6297     T heap_oop = oopDesc::load_heap_oop(p);
6298     if (!oopDesc::is_null(heap_oop)) {
6299       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6300       HeapRegion* hr = _g1h->heap_region_containing(obj);
6301       assert(!hr->is_continues_humongous(),
6302              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6303              " starting at " HR_FORMAT,
6304              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6305 
6306       hr->remove_strong_code_root(_nm);
6307     }
6308   }
6309 
6310 public:
6311   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6312     _g1h(g1h), _nm(nm) {}
6313 
6314   void do_oop(oop* p)       { do_oop_work(p); }
6315   void do_oop(narrowOop* p) { do_oop_work(p); }
6316 };
6317 
6318 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6319   CollectedHeap::register_nmethod(nm);
6320 
6321   guarantee(nm != NULL, "sanity");
6322   RegisterNMethodOopClosure reg_cl(this, nm);
6323   nm->oops_do(&reg_cl);
6324 }
6325 
6326 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6327   CollectedHeap::unregister_nmethod(nm);
6328 
6329   guarantee(nm != NULL, "sanity");
6330   UnregisterNMethodOopClosure reg_cl(this, nm);
6331   nm->oops_do(&reg_cl, true);
6332 }
6333 
6334 void G1CollectedHeap::purge_code_root_memory() {
6335   double purge_start = os::elapsedTime();
6336   G1CodeRootSet::purge();
6337   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6338   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6339 }
6340 
6341 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6342   G1CollectedHeap* _g1h;
6343 
6344 public:
6345   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6346     _g1h(g1h) {}
6347 
6348   void do_code_blob(CodeBlob* cb) {
6349     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6350     if (nm == NULL) {
6351       return;
6352     }
6353 
6354     if (ScavengeRootsInCode) {
6355       _g1h->register_nmethod(nm);
6356     }
6357   }
6358 };
6359 
6360 void G1CollectedHeap::rebuild_strong_code_roots() {
6361   RebuildStrongCodeRootClosure blob_cl(this);
6362   CodeCache::blobs_do(&blob_cl);
6363 }
--- EOF ---