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/g1GCPhaseTimes.hpp"
  41 #include "gc/g1/g1Log.hpp"
  42 #include "gc/g1/g1MarkSweep.hpp"
  43 #include "gc/g1/g1OopClosures.inline.hpp"
  44 #include "gc/g1/g1ParScanThreadState.inline.hpp"
  45 #include "gc/g1/g1RegionToSpaceMapper.hpp"
  46 #include "gc/g1/g1RemSet.inline.hpp"
  47 #include "gc/g1/g1RootClosures.hpp"
  48 #include "gc/g1/g1RootProcessor.hpp"
  49 #include "gc/g1/g1StringDedup.hpp"
  50 #include "gc/g1/g1YCTypes.hpp"
  51 #include "gc/g1/heapRegion.inline.hpp"
  52 #include "gc/g1/heapRegionRemSet.hpp"
  53 #include "gc/g1/heapRegionSet.inline.hpp"
  54 #include "gc/g1/suspendibleThreadSet.hpp"
  55 #include "gc/g1/vm_operations_g1.hpp"
  56 #include "gc/shared/gcHeapSummary.hpp"
  57 #include "gc/shared/gcId.hpp"
  58 #include "gc/shared/gcLocker.inline.hpp"
  59 #include "gc/shared/gcTimer.hpp"
  60 #include "gc/shared/gcTrace.hpp"
  61 #include "gc/shared/gcTraceTime.hpp"
  62 #include "gc/shared/generationSpec.hpp"
  63 #include "gc/shared/isGCActiveMark.hpp"
  64 #include "gc/shared/referenceProcessor.hpp"
  65 #include "gc/shared/taskqueue.inline.hpp"
  66 #include "memory/allocation.hpp"
  67 #include "memory/iterator.hpp"
  68 #include "oops/oop.inline.hpp"
  69 #include "runtime/atomic.inline.hpp"
  70 #include "runtime/init.hpp"
  71 #include "runtime/orderAccess.inline.hpp"
  72 #include "runtime/vmThread.hpp"
  73 #include "utilities/globalDefinitions.hpp"
  74 #include "utilities/stack.inline.hpp"
  75 
  76 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  77 
  78 // INVARIANTS/NOTES
  79 //
  80 // All allocation activity covered by the G1CollectedHeap interface is
  81 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  82 // and allocate_new_tlab, which are the "entry" points to the
  83 // allocation code from the rest of the JVM.  (Note that this does not
  84 // apply to TLAB allocation, which is not part of this interface: it
  85 // is done by clients of this interface.)
  86 
  87 // Local to this file.
  88 
  89 class RefineCardTableEntryClosure: public CardTableEntryClosure {
  90   bool _concurrent;
  91 public:
  92   RefineCardTableEntryClosure() : _concurrent(true) { }
  93 
  94   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
  95     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
  96     // This path is executed by the concurrent refine or mutator threads,
  97     // concurrently, and so we do not care if card_ptr contains references
  98     // that point into the collection set.
  99     assert(!oops_into_cset, "should be");
 100 
 101     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 102       // Caller will actually yield.
 103       return false;
 104     }
 105     // Otherwise, we finished successfully; return true.
 106     return true;
 107   }
 108 
 109   void set_concurrent(bool b) { _concurrent = b; }
 110 };
 111 
 112 
 113 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 114  private:
 115   size_t _num_processed;
 116 
 117  public:
 118   RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
 119 
 120   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 121     *card_ptr = CardTableModRefBS::dirty_card_val();
 122     _num_processed++;
 123     return true;
 124   }
 125 
 126   size_t num_processed() const { return _num_processed; }
 127 };
 128 
 129 
 130 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
 131   HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
 132 }
 133 
 134 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 135   // The from card cache is not the memory that is actually committed. So we cannot
 136   // take advantage of the zero_filled parameter.
 137   reset_from_card_cache(start_idx, num_regions);
 138 }
 139 
 140 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 141 {
 142   // Claim the right to put the region on the dirty cards region list
 143   // by installing a self pointer.
 144   HeapRegion* next = hr->get_next_dirty_cards_region();
 145   if (next == NULL) {
 146     HeapRegion* res = (HeapRegion*)
 147       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 148                           NULL);
 149     if (res == NULL) {
 150       HeapRegion* head;
 151       do {
 152         // Put the region to the dirty cards region list.
 153         head = _dirty_cards_region_list;
 154         next = (HeapRegion*)
 155           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 156         if (next == head) {
 157           assert(hr->get_next_dirty_cards_region() == hr,
 158                  "hr->get_next_dirty_cards_region() != hr");
 159           if (next == NULL) {
 160             // The last region in the list points to itself.
 161             hr->set_next_dirty_cards_region(hr);
 162           } else {
 163             hr->set_next_dirty_cards_region(next);
 164           }
 165         }
 166       } while (next != head);
 167     }
 168   }
 169 }
 170 
 171 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 172 {
 173   HeapRegion* head;
 174   HeapRegion* hr;
 175   do {
 176     head = _dirty_cards_region_list;
 177     if (head == NULL) {
 178       return NULL;
 179     }
 180     HeapRegion* new_head = head->get_next_dirty_cards_region();
 181     if (head == new_head) {
 182       // The last region.
 183       new_head = NULL;
 184     }
 185     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 186                                           head);
 187   } while (hr != head);
 188   assert(hr != NULL, "invariant");
 189   hr->set_next_dirty_cards_region(NULL);
 190   return hr;
 191 }
 192 
 193 // Returns true if the reference points to an object that
 194 // can move in an incremental collection.
 195 bool G1CollectedHeap::is_scavengable(const void* p) {
 196   HeapRegion* hr = heap_region_containing(p);
 197   return !hr->is_pinned();
 198 }
 199 
 200 // Private methods.
 201 
 202 HeapRegion*
 203 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 204   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 205   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 206     if (!_secondary_free_list.is_empty()) {
 207       if (G1ConcRegionFreeingVerbose) {
 208         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 209                                "secondary_free_list has %u entries",
 210                                _secondary_free_list.length());
 211       }
 212       // It looks as if there are free regions available on the
 213       // secondary_free_list. Let's move them to the free_list and try
 214       // again to allocate from it.
 215       append_secondary_free_list();
 216 
 217       assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
 218              "empty we should have moved at least one entry to the free_list");
 219       HeapRegion* res = _hrm.allocate_free_region(is_old);
 220       if (G1ConcRegionFreeingVerbose) {
 221         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 222                                "allocated " HR_FORMAT " from secondary_free_list",
 223                                HR_FORMAT_PARAMS(res));
 224       }
 225       return res;
 226     }
 227 
 228     // Wait here until we get notified either when (a) there are no
 229     // more free regions coming or (b) some regions have been moved on
 230     // the secondary_free_list.
 231     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 232   }
 233 
 234   if (G1ConcRegionFreeingVerbose) {
 235     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 236                            "could not allocate from secondary_free_list");
 237   }
 238   return NULL;
 239 }
 240 
 241 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 242   assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
 243          "the only time we use this to allocate a humongous region is "
 244          "when we are allocating a single humongous region");
 245 
 246   HeapRegion* res;
 247   if (G1StressConcRegionFreeing) {
 248     if (!_secondary_free_list.is_empty()) {
 249       if (G1ConcRegionFreeingVerbose) {
 250         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 251                                "forced to look at the secondary_free_list");
 252       }
 253       res = new_region_try_secondary_free_list(is_old);
 254       if (res != NULL) {
 255         return res;
 256       }
 257     }
 258   }
 259 
 260   res = _hrm.allocate_free_region(is_old);
 261 
 262   if (res == NULL) {
 263     if (G1ConcRegionFreeingVerbose) {
 264       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 265                              "res == NULL, trying the secondary_free_list");
 266     }
 267     res = new_region_try_secondary_free_list(is_old);
 268   }
 269   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 270     // Currently, only attempts to allocate GC alloc regions set
 271     // do_expand to true. So, we should only reach here during a
 272     // safepoint. If this assumption changes we might have to
 273     // reconsider the use of _expand_heap_after_alloc_failure.
 274     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 275 
 276     ergo_verbose1(ErgoHeapSizing,
 277                   "attempt heap expansion",
 278                   ergo_format_reason("region allocation request failed")
 279                   ergo_format_byte("allocation request"),
 280                   word_size * HeapWordSize);
 281     if (expand(word_size * HeapWordSize)) {
 282       // Given that expand() succeeded in expanding the heap, and we
 283       // always expand the heap by an amount aligned to the heap
 284       // region size, the free list should in theory not be empty.
 285       // In either case allocate_free_region() will check for NULL.
 286       res = _hrm.allocate_free_region(is_old);
 287     } else {
 288       _expand_heap_after_alloc_failure = false;
 289     }
 290   }
 291   return res;
 292 }
 293 
 294 HeapWord*
 295 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 296                                                            uint num_regions,
 297                                                            size_t word_size,
 298                                                            AllocationContext_t context) {
 299   assert(first != G1_NO_HRM_INDEX, "pre-condition");
 300   assert(is_humongous(word_size), "word_size should be humongous");
 301   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 302 
 303   // Index of last region in the series + 1.
 304   uint last = first + num_regions;
 305 
 306   // We need to initialize the region(s) we just discovered. This is
 307   // a bit tricky given that it can happen concurrently with
 308   // refinement threads refining cards on these regions and
 309   // potentially wanting to refine the BOT as they are scanning
 310   // those cards (this can happen shortly after a cleanup; see CR
 311   // 6991377). So we have to set up the region(s) carefully and in
 312   // a specific order.
 313 
 314   // The word size sum of all the regions we will allocate.
 315   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 316   assert(word_size <= word_size_sum, "sanity");
 317 
 318   // This will be the "starts humongous" region.
 319   HeapRegion* first_hr = region_at(first);
 320   // The header of the new object will be placed at the bottom of
 321   // the first region.
 322   HeapWord* new_obj = first_hr->bottom();
 323   // This will be the new end of the first region in the series that
 324   // should also match the end of the last region in the series.
 325   HeapWord* new_end = new_obj + word_size_sum;
 326   // This will be the new top of the first region that will reflect
 327   // this allocation.
 328   HeapWord* new_top = new_obj + word_size;
 329 
 330   // First, we need to zero the header of the space that we will be
 331   // allocating. When we update top further down, some refinement
 332   // threads might try to scan the region. By zeroing the header we
 333   // ensure that any thread that will try to scan the region will
 334   // come across the zero klass word and bail out.
 335   //
 336   // NOTE: It would not have been correct to have used
 337   // CollectedHeap::fill_with_object() and make the space look like
 338   // an int array. The thread that is doing the allocation will
 339   // later update the object header to a potentially different array
 340   // type and, for a very short period of time, the klass and length
 341   // fields will be inconsistent. This could cause a refinement
 342   // thread to calculate the object size incorrectly.
 343   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 344 
 345   // We will set up the first region as "starts humongous". This
 346   // will also update the BOT covering all the regions to reflect
 347   // that there is a single object that starts at the bottom of the
 348   // first region.
 349   first_hr->set_starts_humongous(new_top, new_end);
 350   first_hr->set_allocation_context(context);
 351   // Then, if there are any, we will set up the "continues
 352   // humongous" regions.
 353   HeapRegion* hr = NULL;
 354   for (uint i = first + 1; i < last; ++i) {
 355     hr = region_at(i);
 356     hr->set_continues_humongous(first_hr);
 357     hr->set_allocation_context(context);
 358   }
 359   // If we have "continues humongous" regions (hr != NULL), then the
 360   // end of the last one should match new_end.
 361   assert(hr == NULL || hr->end() == new_end, "sanity");
 362 
 363   // Up to this point no concurrent thread would have been able to
 364   // do any scanning on any region in this series. All the top
 365   // fields still point to bottom, so the intersection between
 366   // [bottom,top] and [card_start,card_end] will be empty. Before we
 367   // update the top fields, we'll do a storestore to make sure that
 368   // no thread sees the update to top before the zeroing of the
 369   // object header and the BOT initialization.
 370   OrderAccess::storestore();
 371 
 372   // Now that the BOT and the object header have been initialized,
 373   // we can update top of the "starts humongous" region.
 374   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 375          "new_top should be in this region");
 376   first_hr->set_top(new_top);
 377   if (_hr_printer.is_active()) {
 378     HeapWord* bottom = first_hr->bottom();
 379     HeapWord* end = first_hr->orig_end();
 380     if ((first + 1) == last) {
 381       // the series has a single humongous region
 382       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 383     } else {
 384       // the series has more than one humongous regions
 385       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 386     }
 387   }
 388 
 389   // Now, we will update the top fields of the "continues humongous"
 390   // regions. The reason we need to do this is that, otherwise,
 391   // these regions would look empty and this will confuse parts of
 392   // G1. For example, the code that looks for a consecutive number
 393   // of empty regions will consider them empty and try to
 394   // re-allocate them. We can extend is_empty() to also include
 395   // !is_continues_humongous(), but it is easier to just update the top
 396   // fields here. The way we set top for all regions (i.e., top ==
 397   // end for all regions but the last one, top == new_top for the
 398   // last one) is actually used when we will free up the humongous
 399   // region in free_humongous_region().
 400   hr = NULL;
 401   for (uint i = first + 1; i < last; ++i) {
 402     hr = region_at(i);
 403     if ((i + 1) == last) {
 404       // last continues humongous region
 405       assert(hr->bottom() < new_top && new_top <= hr->end(),
 406              "new_top should fall on this region");
 407       hr->set_top(new_top);
 408       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 409     } else {
 410       // not last one
 411       assert(new_top > hr->end(), "new_top should be above this region");
 412       hr->set_top(hr->end());
 413       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 414     }
 415   }
 416   // If we have continues humongous regions (hr != NULL), then the
 417   // end of the last one should match new_end and its top should
 418   // match new_top.
 419   assert(hr == NULL ||
 420          (hr->end() == new_end && hr->top() == new_top), "sanity");
 421   check_bitmaps("Humongous Region Allocation", first_hr);
 422 
 423   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 424   increase_used(first_hr->used());
 425   _humongous_set.add(first_hr);
 426 
 427   return new_obj;
 428 }
 429 
 430 // If could fit into free regions w/o expansion, try.
 431 // Otherwise, if can expand, do so.
 432 // Otherwise, if using ex regions might help, try with ex given back.
 433 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
 434   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 435 
 436   verify_region_sets_optional();
 437 
 438   uint first = G1_NO_HRM_INDEX;
 439   uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
 440 
 441   if (obj_regions == 1) {
 442     // Only one region to allocate, try to use a fast path by directly allocating
 443     // from the free lists. Do not try to expand here, we will potentially do that
 444     // later.
 445     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 446     if (hr != NULL) {
 447       first = hr->hrm_index();
 448     }
 449   } else {
 450     // We can't allocate humongous regions spanning more than one region while
 451     // cleanupComplete() is running, since some of the regions we find to be
 452     // empty might not yet be added to the free list. It is not straightforward
 453     // to know in which list they are on so that we can remove them. We only
 454     // need to do this if we need to allocate more than one region to satisfy the
 455     // current humongous allocation request. If we are only allocating one region
 456     // we use the one-region region allocation code (see above), that already
 457     // potentially waits for regions from the secondary free list.
 458     wait_while_free_regions_coming();
 459     append_secondary_free_list_if_not_empty_with_lock();
 460 
 461     // Policy: Try only empty regions (i.e. already committed first). Maybe we
 462     // are lucky enough to find some.
 463     first = _hrm.find_contiguous_only_empty(obj_regions);
 464     if (first != G1_NO_HRM_INDEX) {
 465       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 466     }
 467   }
 468 
 469   if (first == G1_NO_HRM_INDEX) {
 470     // Policy: We could not find enough regions for the humongous object in the
 471     // free list. Look through the heap to find a mix of free and uncommitted regions.
 472     // If so, try expansion.
 473     first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
 474     if (first != G1_NO_HRM_INDEX) {
 475       // We found something. Make sure these regions are committed, i.e. expand
 476       // the heap. Alternatively we could do a defragmentation GC.
 477       ergo_verbose1(ErgoHeapSizing,
 478                     "attempt heap expansion",
 479                     ergo_format_reason("humongous allocation request failed")
 480                     ergo_format_byte("allocation request"),
 481                     word_size * HeapWordSize);
 482 
 483       _hrm.expand_at(first, obj_regions);
 484       g1_policy()->record_new_heap_size(num_regions());
 485 
 486 #ifdef ASSERT
 487       for (uint i = first; i < first + obj_regions; ++i) {
 488         HeapRegion* hr = region_at(i);
 489         assert(hr->is_free(), "sanity");
 490         assert(hr->is_empty(), "sanity");
 491         assert(is_on_master_free_list(hr), "sanity");
 492       }
 493 #endif
 494       _hrm.allocate_free_regions_starting_at(first, obj_regions);
 495     } else {
 496       // Policy: Potentially trigger a defragmentation GC.
 497     }
 498   }
 499 
 500   HeapWord* result = NULL;
 501   if (first != G1_NO_HRM_INDEX) {
 502     result = humongous_obj_allocate_initialize_regions(first, obj_regions,
 503                                                        word_size, context);
 504     assert(result != NULL, "it should always return a valid result");
 505 
 506     // A successful humongous object allocation changes the used space
 507     // information of the old generation so we need to recalculate the
 508     // sizes and update the jstat counters here.
 509     g1mm()->update_sizes();
 510   }
 511 
 512   verify_region_sets_optional();
 513 
 514   return result;
 515 }
 516 
 517 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 518   assert_heap_not_locked_and_not_at_safepoint();
 519   assert(!is_humongous(word_size), "we do not allow humongous TLABs");
 520 
 521   uint dummy_gc_count_before;
 522   uint dummy_gclocker_retry_count = 0;
 523   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 524 }
 525 
 526 HeapWord*
 527 G1CollectedHeap::mem_allocate(size_t word_size,
 528                               bool*  gc_overhead_limit_was_exceeded) {
 529   assert_heap_not_locked_and_not_at_safepoint();
 530 
 531   // Loop until the allocation is satisfied, or unsatisfied after GC.
 532   for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 533     uint gc_count_before;
 534 
 535     HeapWord* result = NULL;
 536     if (!is_humongous(word_size)) {
 537       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 538     } else {
 539       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 540     }
 541     if (result != NULL) {
 542       return result;
 543     }
 544 
 545     // Create the garbage collection operation...
 546     VM_G1CollectForAllocation op(gc_count_before, word_size);
 547     op.set_allocation_context(AllocationContext::current());
 548 
 549     // ...and get the VM thread to execute it.
 550     VMThread::execute(&op);
 551 
 552     if (op.prologue_succeeded() && op.pause_succeeded()) {
 553       // If the operation was successful we'll return the result even
 554       // if it is NULL. If the allocation attempt failed immediately
 555       // after a Full GC, it's unlikely we'll be able to allocate now.
 556       HeapWord* result = op.result();
 557       if (result != NULL && !is_humongous(word_size)) {
 558         // Allocations that take place on VM operations do not do any
 559         // card dirtying and we have to do it here. We only have to do
 560         // this for non-humongous allocations, though.
 561         dirty_young_block(result, word_size);
 562       }
 563       return result;
 564     } else {
 565       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 566         return NULL;
 567       }
 568       assert(op.result() == NULL,
 569              "the result should be NULL if the VM op did not succeed");
 570     }
 571 
 572     // Give a warning if we seem to be looping forever.
 573     if ((QueuedAllocationWarningCount > 0) &&
 574         (try_count % QueuedAllocationWarningCount == 0)) {
 575       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 576     }
 577   }
 578 
 579   ShouldNotReachHere();
 580   return NULL;
 581 }
 582 
 583 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 584                                                    AllocationContext_t context,
 585                                                    uint* gc_count_before_ret,
 586                                                    uint* gclocker_retry_count_ret) {
 587   // Make sure you read the note in attempt_allocation_humongous().
 588 
 589   assert_heap_not_locked_and_not_at_safepoint();
 590   assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
 591          "be called for humongous allocation requests");
 592 
 593   // We should only get here after the first-level allocation attempt
 594   // (attempt_allocation()) failed to allocate.
 595 
 596   // We will loop until a) we manage to successfully perform the
 597   // allocation or b) we successfully schedule a collection which
 598   // fails to perform the allocation. b) is the only case when we'll
 599   // return NULL.
 600   HeapWord* result = NULL;
 601   for (int try_count = 1; /* we'll return */; try_count += 1) {
 602     bool should_try_gc;
 603     uint gc_count_before;
 604 
 605     {
 606       MutexLockerEx x(Heap_lock);
 607       result = _allocator->attempt_allocation_locked(word_size, context);
 608       if (result != NULL) {
 609         return result;
 610       }
 611 
 612       if (GC_locker::is_active_and_needs_gc()) {
 613         if (g1_policy()->can_expand_young_list()) {
 614           // No need for an ergo verbose message here,
 615           // can_expand_young_list() does this when it returns true.
 616           result = _allocator->attempt_allocation_force(word_size, context);
 617           if (result != NULL) {
 618             return result;
 619           }
 620         }
 621         should_try_gc = false;
 622       } else {
 623         // The GCLocker may not be active but the GCLocker initiated
 624         // GC may not yet have been performed (GCLocker::needs_gc()
 625         // returns true). In this case we do not try this GC and
 626         // wait until the GCLocker initiated GC is performed, and
 627         // then retry the allocation.
 628         if (GC_locker::needs_gc()) {
 629           should_try_gc = false;
 630         } else {
 631           // Read the GC count while still holding the Heap_lock.
 632           gc_count_before = total_collections();
 633           should_try_gc = true;
 634         }
 635       }
 636     }
 637 
 638     if (should_try_gc) {
 639       bool succeeded;
 640       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 641                                    GCCause::_g1_inc_collection_pause);
 642       if (result != NULL) {
 643         assert(succeeded, "only way to get back a non-NULL result");
 644         return result;
 645       }
 646 
 647       if (succeeded) {
 648         // If we get here we successfully scheduled a collection which
 649         // failed to allocate. No point in trying to allocate
 650         // further. We'll just return NULL.
 651         MutexLockerEx x(Heap_lock);
 652         *gc_count_before_ret = total_collections();
 653         return NULL;
 654       }
 655     } else {
 656       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 657         MutexLockerEx x(Heap_lock);
 658         *gc_count_before_ret = total_collections();
 659         return NULL;
 660       }
 661       // The GCLocker is either active or the GCLocker initiated
 662       // GC has not yet been performed. Stall until it is and
 663       // then retry the allocation.
 664       GC_locker::stall_until_clear();
 665       (*gclocker_retry_count_ret) += 1;
 666     }
 667 
 668     // We can reach here if we were unsuccessful in scheduling a
 669     // collection (because another thread beat us to it) or if we were
 670     // stalled due to the GC locker. In either can we should retry the
 671     // allocation attempt in case another thread successfully
 672     // performed a collection and reclaimed enough space. We do the
 673     // first attempt (without holding the Heap_lock) here and the
 674     // follow-on attempt will be at the start of the next loop
 675     // iteration (after taking the Heap_lock).
 676     result = _allocator->attempt_allocation(word_size, context);
 677     if (result != NULL) {
 678       return result;
 679     }
 680 
 681     // Give a warning if we seem to be looping forever.
 682     if ((QueuedAllocationWarningCount > 0) &&
 683         (try_count % QueuedAllocationWarningCount == 0)) {
 684       warning("G1CollectedHeap::attempt_allocation_slow() "
 685               "retries %d times", try_count);
 686     }
 687   }
 688 
 689   ShouldNotReachHere();
 690   return NULL;
 691 }
 692 
 693 void G1CollectedHeap::begin_archive_alloc_range() {
 694   assert_at_safepoint(true /* should_be_vm_thread */);
 695   if (_archive_allocator == NULL) {
 696     _archive_allocator = G1ArchiveAllocator::create_allocator(this);
 697   }
 698 }
 699 
 700 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
 701   // Allocations in archive regions cannot be of a size that would be considered
 702   // humongous even for a minimum-sized region, because G1 region sizes/boundaries
 703   // may be different at archive-restore time.
 704   return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
 705 }
 706 
 707 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
 708   assert_at_safepoint(true /* should_be_vm_thread */);
 709   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 710   if (is_archive_alloc_too_large(word_size)) {
 711     return NULL;
 712   }
 713   return _archive_allocator->archive_mem_allocate(word_size);
 714 }
 715 
 716 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 717                                               size_t end_alignment_in_bytes) {
 718   assert_at_safepoint(true /* should_be_vm_thread */);
 719   assert(_archive_allocator != NULL, "_archive_allocator not initialized");
 720 
 721   // Call complete_archive to do the real work, filling in the MemRegion
 722   // array with the archive regions.
 723   _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
 724   delete _archive_allocator;
 725   _archive_allocator = NULL;
 726 }
 727 
 728 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
 729   assert(ranges != NULL, "MemRegion array NULL");
 730   assert(count != 0, "No MemRegions provided");
 731   MemRegion reserved = _hrm.reserved();
 732   for (size_t i = 0; i < count; i++) {
 733     if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
 734       return false;
 735     }
 736   }
 737   return true;
 738 }
 739 
 740 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
 741   assert(!is_init_completed(), "Expect to be called at JVM init time");
 742   assert(ranges != NULL, "MemRegion array NULL");
 743   assert(count != 0, "No MemRegions provided");
 744   MutexLockerEx x(Heap_lock);
 745 
 746   MemRegion reserved = _hrm.reserved();
 747   HeapWord* prev_last_addr = NULL;
 748   HeapRegion* prev_last_region = NULL;
 749 
 750   // Temporarily disable pretouching of heap pages. This interface is used
 751   // when mmap'ing archived heap data in, so pre-touching is wasted.
 752   FlagSetting fs(AlwaysPreTouch, false);
 753 
 754   // Enable archive object checking in G1MarkSweep. We have to let it know
 755   // about each archive range, so that objects in those ranges aren't marked.
 756   G1MarkSweep::enable_archive_object_check();
 757 
 758   // For each specified MemRegion range, allocate the corresponding G1
 759   // regions and mark them as archive regions. We expect the ranges in
 760   // ascending starting address order, without overlap.
 761   for (size_t i = 0; i < count; i++) {
 762     MemRegion curr_range = ranges[i];
 763     HeapWord* start_address = curr_range.start();
 764     size_t word_size = curr_range.word_size();
 765     HeapWord* last_address = curr_range.last();
 766     size_t commits = 0;
 767 
 768     guarantee(reserved.contains(start_address) && reserved.contains(last_address),
 769               "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 770               p2i(start_address), p2i(last_address));
 771     guarantee(start_address > prev_last_addr,
 772               "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 773               p2i(start_address), p2i(prev_last_addr));
 774     prev_last_addr = last_address;
 775 
 776     // Check for ranges that start in the same G1 region in which the previous
 777     // range ended, and adjust the start address so we don't try to allocate
 778     // the same region again. If the current range is entirely within that
 779     // region, skip it, just adjusting the recorded top.
 780     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 781     if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
 782       start_address = start_region->end();
 783       if (start_address > last_address) {
 784         increase_used(word_size * HeapWordSize);
 785         start_region->set_top(last_address + 1);
 786         continue;
 787       }
 788       start_region->set_top(start_address);
 789       curr_range = MemRegion(start_address, last_address + 1);
 790       start_region = _hrm.addr_to_region(start_address);
 791     }
 792 
 793     // Perform the actual region allocation, exiting if it fails.
 794     // Then note how much new space we have allocated.
 795     if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
 796       return false;
 797     }
 798     increase_used(word_size * HeapWordSize);
 799     if (commits != 0) {
 800       ergo_verbose1(ErgoHeapSizing,
 801                     "attempt heap expansion",
 802                     ergo_format_reason("allocate archive regions")
 803                     ergo_format_byte("total size"),
 804                     HeapRegion::GrainWords * HeapWordSize * commits);
 805     }
 806 
 807     // Mark each G1 region touched by the range as archive, add it to the old set,
 808     // and set the allocation context and top.
 809     HeapRegion* curr_region = _hrm.addr_to_region(start_address);
 810     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 811     prev_last_region = last_region;
 812 
 813     while (curr_region != NULL) {
 814       assert(curr_region->is_empty() && !curr_region->is_pinned(),
 815              "Region already in use (index %u)", curr_region->hrm_index());
 816       _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
 817       curr_region->set_allocation_context(AllocationContext::system());
 818       curr_region->set_archive();
 819       _old_set.add(curr_region);
 820       if (curr_region != last_region) {
 821         curr_region->set_top(curr_region->end());
 822         curr_region = _hrm.next_region_in_heap(curr_region);
 823       } else {
 824         curr_region->set_top(last_address + 1);
 825         curr_region = NULL;
 826       }
 827     }
 828 
 829     // Notify mark-sweep of the archive range.
 830     G1MarkSweep::set_range_archive(curr_range, true);
 831   }
 832   return true;
 833 }
 834 
 835 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
 836   assert(!is_init_completed(), "Expect to be called at JVM init time");
 837   assert(ranges != NULL, "MemRegion array NULL");
 838   assert(count != 0, "No MemRegions provided");
 839   MemRegion reserved = _hrm.reserved();
 840   HeapWord *prev_last_addr = NULL;
 841   HeapRegion* prev_last_region = NULL;
 842 
 843   // For each MemRegion, create filler objects, if needed, in the G1 regions
 844   // that contain the address range. The address range actually within the
 845   // MemRegion will not be modified. That is assumed to have been initialized
 846   // elsewhere, probably via an mmap of archived heap data.
 847   MutexLockerEx x(Heap_lock);
 848   for (size_t i = 0; i < count; i++) {
 849     HeapWord* start_address = ranges[i].start();
 850     HeapWord* last_address = ranges[i].last();
 851 
 852     assert(reserved.contains(start_address) && reserved.contains(last_address),
 853            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 854            p2i(start_address), p2i(last_address));
 855     assert(start_address > prev_last_addr,
 856            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 857            p2i(start_address), p2i(prev_last_addr));
 858 
 859     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 860     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 861     HeapWord* bottom_address = start_region->bottom();
 862 
 863     // Check for a range beginning in the same region in which the
 864     // previous one ended.
 865     if (start_region == prev_last_region) {
 866       bottom_address = prev_last_addr + 1;
 867     }
 868 
 869     // Verify that the regions were all marked as archive regions by
 870     // alloc_archive_regions.
 871     HeapRegion* curr_region = start_region;
 872     while (curr_region != NULL) {
 873       guarantee(curr_region->is_archive(),
 874                 "Expected archive region at index %u", curr_region->hrm_index());
 875       if (curr_region != last_region) {
 876         curr_region = _hrm.next_region_in_heap(curr_region);
 877       } else {
 878         curr_region = NULL;
 879       }
 880     }
 881 
 882     prev_last_addr = last_address;
 883     prev_last_region = last_region;
 884 
 885     // Fill the memory below the allocated range with dummy object(s),
 886     // if the region bottom does not match the range start, or if the previous
 887     // range ended within the same G1 region, and there is a gap.
 888     if (start_address != bottom_address) {
 889       size_t fill_size = pointer_delta(start_address, bottom_address);
 890       G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
 891       increase_used(fill_size * HeapWordSize);
 892     }
 893   }
 894 }
 895 










 896 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
 897                                                      uint* gc_count_before_ret,
 898                                                      uint* gclocker_retry_count_ret) {
 899   assert_heap_not_locked_and_not_at_safepoint();
 900   assert(!is_humongous(word_size), "attempt_allocation() should not "
 901          "be called for humongous allocation requests");
 902 
 903   AllocationContext_t context = AllocationContext::current();
 904   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 905 
 906   if (result == NULL) {
 907     result = attempt_allocation_slow(word_size,
 908                                      context,
 909                                      gc_count_before_ret,
 910                                      gclocker_retry_count_ret);
 911   }
 912   assert_heap_not_locked();
 913   if (result != NULL) {
 914     dirty_young_block(result, word_size);
 915   }
 916   return result;
 917 }
 918 
 919 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 920   assert(!is_init_completed(), "Expect to be called at JVM init time");
 921   assert(ranges != NULL, "MemRegion array NULL");
 922   assert(count != 0, "No MemRegions provided");
 923   MemRegion reserved = _hrm.reserved();
 924   HeapWord* prev_last_addr = NULL;
 925   HeapRegion* prev_last_region = NULL;
 926   size_t size_used = 0;
 927   size_t uncommitted_regions = 0;
 928 
 929   // For each Memregion, free the G1 regions that constitute it, and
 930   // notify mark-sweep that the range is no longer to be considered 'archive.'
 931   MutexLockerEx x(Heap_lock);
 932   for (size_t i = 0; i < count; i++) {
 933     HeapWord* start_address = ranges[i].start();
 934     HeapWord* last_address = ranges[i].last();
 935 
 936     assert(reserved.contains(start_address) && reserved.contains(last_address),
 937            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 938            p2i(start_address), p2i(last_address));
 939     assert(start_address > prev_last_addr,
 940            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 941            p2i(start_address), p2i(prev_last_addr));
 942     size_used += ranges[i].byte_size();
 943     prev_last_addr = last_address;
 944 
 945     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 946     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 947 
 948     // Check for ranges that start in the same G1 region in which the previous
 949     // range ended, and adjust the start address so we don't try to free
 950     // the same region again. If the current range is entirely within that
 951     // region, skip it.
 952     if (start_region == prev_last_region) {
 953       start_address = start_region->end();
 954       if (start_address > last_address) {
 955         continue;
 956       }
 957       start_region = _hrm.addr_to_region(start_address);
 958     }
 959     prev_last_region = last_region;
 960 
 961     // After verifying that each region was marked as an archive region by
 962     // alloc_archive_regions, set it free and empty and uncommit it.
 963     HeapRegion* curr_region = start_region;
 964     while (curr_region != NULL) {
 965       guarantee(curr_region->is_archive(),
 966                 "Expected archive region at index %u", curr_region->hrm_index());
 967       uint curr_index = curr_region->hrm_index();
 968       _old_set.remove(curr_region);
 969       curr_region->set_free();
 970       curr_region->set_top(curr_region->bottom());
 971       if (curr_region != last_region) {
 972         curr_region = _hrm.next_region_in_heap(curr_region);
 973       } else {
 974         curr_region = NULL;
 975       }
 976       _hrm.shrink_at(curr_index, 1);
 977       uncommitted_regions++;
 978     }
 979 
 980     // Notify mark-sweep that this is no longer an archive range.
 981     G1MarkSweep::set_range_archive(ranges[i], false);
 982   }
 983 
 984   if (uncommitted_regions != 0) {
 985     ergo_verbose1(ErgoHeapSizing,
 986                   "attempt heap shrinking",
 987                   ergo_format_reason("uncommitted archive regions")
 988                   ergo_format_byte("total size"),
 989                   HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
 990   }
 991   decrease_used(size_used);
 992 }
 993 
 994 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
 995                                                         uint* gc_count_before_ret,
 996                                                         uint* gclocker_retry_count_ret) {
 997   // The structure of this method has a lot of similarities to
 998   // attempt_allocation_slow(). The reason these two were not merged
 999   // into a single one is that such a method would require several "if
1000   // allocation is not humongous do this, otherwise do that"
1001   // conditional paths which would obscure its flow. In fact, an early
1002   // version of this code did use a unified method which was harder to
1003   // follow and, as a result, it had subtle bugs that were hard to
1004   // track down. So keeping these two methods separate allows each to
1005   // be more readable. It will be good to keep these two in sync as
1006   // much as possible.
1007 
1008   assert_heap_not_locked_and_not_at_safepoint();
1009   assert(is_humongous(word_size), "attempt_allocation_humongous() "
1010          "should only be called for humongous allocations");
1011 
1012   // Humongous objects can exhaust the heap quickly, so we should check if we
1013   // need to start a marking cycle at each humongous object allocation. We do
1014   // the check before we do the actual allocation. The reason for doing it
1015   // before the allocation is that we avoid having to keep track of the newly
1016   // allocated memory while we do a GC.
1017   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1018                                            word_size)) {
1019     collect(GCCause::_g1_humongous_allocation);
1020   }
1021 
1022   // We will loop until a) we manage to successfully perform the
1023   // allocation or b) we successfully schedule a collection which
1024   // fails to perform the allocation. b) is the only case when we'll
1025   // return NULL.
1026   HeapWord* result = NULL;
1027   for (int try_count = 1; /* we'll return */; try_count += 1) {
1028     bool should_try_gc;
1029     uint gc_count_before;
1030 
1031     {
1032       MutexLockerEx x(Heap_lock);
1033 
1034       // Given that humongous objects are not allocated in young
1035       // regions, we'll first try to do the allocation without doing a
1036       // collection hoping that there's enough space in the heap.
1037       result = humongous_obj_allocate(word_size, AllocationContext::current());
1038       if (result != NULL) {
1039         return result;
1040       }
1041 
1042       if (GC_locker::is_active_and_needs_gc()) {
1043         should_try_gc = false;
1044       } else {
1045          // The GCLocker may not be active but the GCLocker initiated
1046         // GC may not yet have been performed (GCLocker::needs_gc()
1047         // returns true). In this case we do not try this GC and
1048         // wait until the GCLocker initiated GC is performed, and
1049         // then retry the allocation.
1050         if (GC_locker::needs_gc()) {
1051           should_try_gc = false;
1052         } else {
1053           // Read the GC count while still holding the Heap_lock.
1054           gc_count_before = total_collections();
1055           should_try_gc = true;
1056         }
1057       }
1058     }
1059 
1060     if (should_try_gc) {
1061       // If we failed to allocate the humongous object, we should try to
1062       // do a collection pause (if we're allowed) in case it reclaims
1063       // enough space for the allocation to succeed after the pause.
1064 
1065       bool succeeded;
1066       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1067                                    GCCause::_g1_humongous_allocation);
1068       if (result != NULL) {
1069         assert(succeeded, "only way to get back a non-NULL result");
1070         return result;
1071       }
1072 
1073       if (succeeded) {
1074         // If we get here we successfully scheduled a collection which
1075         // failed to allocate. No point in trying to allocate
1076         // further. We'll just return NULL.
1077         MutexLockerEx x(Heap_lock);
1078         *gc_count_before_ret = total_collections();
1079         return NULL;
1080       }
1081     } else {
1082       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1083         MutexLockerEx x(Heap_lock);
1084         *gc_count_before_ret = total_collections();
1085         return NULL;
1086       }
1087       // The GCLocker is either active or the GCLocker initiated
1088       // GC has not yet been performed. Stall until it is and
1089       // then retry the allocation.
1090       GC_locker::stall_until_clear();
1091       (*gclocker_retry_count_ret) += 1;
1092     }
1093 
1094     // We can reach here if we were unsuccessful in scheduling a
1095     // collection (because another thread beat us to it) or if we were
1096     // stalled due to the GC locker. In either can we should retry the
1097     // allocation attempt in case another thread successfully
1098     // performed a collection and reclaimed enough space.  Give a
1099     // warning if we seem to be looping forever.
1100 
1101     if ((QueuedAllocationWarningCount > 0) &&
1102         (try_count % QueuedAllocationWarningCount == 0)) {
1103       warning("G1CollectedHeap::attempt_allocation_humongous() "
1104               "retries %d times", try_count);
1105     }
1106   }
1107 
1108   ShouldNotReachHere();
1109   return NULL;
1110 }
1111 
1112 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1113                                                            AllocationContext_t context,
1114                                                            bool expect_null_mutator_alloc_region) {
1115   assert_at_safepoint(true /* should_be_vm_thread */);
1116   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1117          "the current alloc region was unexpectedly found to be non-NULL");
1118 
1119   if (!is_humongous(word_size)) {
1120     return _allocator->attempt_allocation_locked(word_size, context);
1121   } else {
1122     HeapWord* result = humongous_obj_allocate(word_size, context);
1123     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1124       collector_state()->set_initiate_conc_mark_if_possible(true);
1125     }
1126     return result;
1127   }
1128 
1129   ShouldNotReachHere();
1130 }
1131 
1132 class PostMCRemSetClearClosure: public HeapRegionClosure {
1133   G1CollectedHeap* _g1h;
1134   ModRefBarrierSet* _mr_bs;
1135 public:
1136   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1137     _g1h(g1h), _mr_bs(mr_bs) {}
1138 
1139   bool doHeapRegion(HeapRegion* r) {
1140     HeapRegionRemSet* hrrs = r->rem_set();
1141 
1142     if (r->is_continues_humongous()) {
1143       // We'll assert that the strong code root list and RSet is empty
1144       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1145       assert(hrrs->occupied() == 0, "RSet should be empty");
1146       return false;
1147     }
1148 
1149     _g1h->reset_gc_time_stamps(r);
1150     hrrs->clear();
1151     // You might think here that we could clear just the cards
1152     // corresponding to the used region.  But no: if we leave a dirty card
1153     // in a region we might allocate into, then it would prevent that card
1154     // from being enqueued, and cause it to be missed.
1155     // Re: the performance cost: we shouldn't be doing full GC anyway!
1156     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1157 
1158     return false;
1159   }
1160 };
1161 
1162 void G1CollectedHeap::clear_rsets_post_compaction() {
1163   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1164   heap_region_iterate(&rs_clear);
1165 }
1166 
1167 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1168   G1CollectedHeap*   _g1h;
1169   UpdateRSOopClosure _cl;
1170 public:
1171   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1172     _cl(g1->g1_rem_set(), worker_i),
1173     _g1h(g1)
1174   { }
1175 
1176   bool doHeapRegion(HeapRegion* r) {
1177     if (!r->is_continues_humongous()) {
1178       _cl.set_from(r);
1179       r->oop_iterate(&_cl);
1180     }
1181     return false;
1182   }
1183 };
1184 
1185 class ParRebuildRSTask: public AbstractGangTask {
1186   G1CollectedHeap* _g1;
1187   HeapRegionClaimer _hrclaimer;
1188 
1189 public:
1190   ParRebuildRSTask(G1CollectedHeap* g1) :
1191       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1192 
1193   void work(uint worker_id) {
1194     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1195     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1196   }
1197 };
1198 
1199 class PostCompactionPrinterClosure: public HeapRegionClosure {
1200 private:
1201   G1HRPrinter* _hr_printer;
1202 public:
1203   bool doHeapRegion(HeapRegion* hr) {
1204     assert(!hr->is_young(), "not expecting to find young regions");
1205     if (hr->is_free()) {
1206       // We only generate output for non-empty regions.
1207     } else if (hr->is_starts_humongous()) {
1208       if (hr->region_num() == 1) {
1209         // single humongous region
1210         _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1211       } else {
1212         _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1213       }
1214     } else if (hr->is_continues_humongous()) {
1215       _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1216     } else if (hr->is_archive()) {
1217       _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1218     } else if (hr->is_old()) {
1219       _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1220     } else {
1221       ShouldNotReachHere();
1222     }
1223     return false;
1224   }
1225 
1226   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1227     : _hr_printer(hr_printer) { }
1228 };
1229 
1230 void G1CollectedHeap::print_hrm_post_compaction() {
1231   PostCompactionPrinterClosure cl(hr_printer());
1232   heap_region_iterate(&cl);
1233 }
1234 
1235 bool G1CollectedHeap::do_collection(bool explicit_gc,
1236                                     bool clear_all_soft_refs,
1237                                     size_t word_size) {
1238   assert_at_safepoint(true /* should_be_vm_thread */);
1239 
1240   if (GC_locker::check_active_before_gc()) {
1241     return false;
1242   }
1243 
1244   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1245   gc_timer->register_gc_start();
1246 
1247   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1248   GCIdMark gc_id_mark;
1249   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1250 
1251   SvcGCMarker sgcm(SvcGCMarker::FULL);
1252   ResourceMark rm;
1253 
1254   G1Log::update_level();
1255   print_heap_before_gc();
1256   trace_heap_before_gc(gc_tracer);
1257 
1258   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1259 
1260   verify_region_sets_optional();
1261 
1262   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1263                            collector_policy()->should_clear_all_soft_refs();
1264 
1265   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1266 
1267   {
1268     IsGCActiveMark x;
1269 
1270     // Timing
1271     assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1272     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1273 
1274     {
1275       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1276       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1277       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1278 
1279       g1_policy()->record_full_collection_start();
1280 
1281       // Note: When we have a more flexible GC logging framework that
1282       // allows us to add optional attributes to a GC log record we
1283       // could consider timing and reporting how long we wait in the
1284       // following two methods.
1285       wait_while_free_regions_coming();
1286       // If we start the compaction before the CM threads finish
1287       // scanning the root regions we might trip them over as we'll
1288       // be moving objects / updating references. So let's wait until
1289       // they are done. By telling them to abort, they should complete
1290       // early.
1291       _cm->root_regions()->abort();
1292       _cm->root_regions()->wait_until_scan_finished();
1293       append_secondary_free_list_if_not_empty_with_lock();
1294 
1295       gc_prologue(true);
1296       increment_total_collections(true /* full gc */);
1297       increment_old_marking_cycles_started();
1298 
1299       assert(used() == recalculate_used(), "Should be equal");
1300 
1301       verify_before_gc();
1302 
1303       check_bitmaps("Full GC Start");
1304       pre_full_gc_dump(gc_timer);
1305 
1306 #if defined(COMPILER2) || INCLUDE_JVMCI
1307       DerivedPointerTable::clear();
1308 #endif
1309 
1310       // Disable discovery and empty the discovered lists
1311       // for the CM ref processor.
1312       ref_processor_cm()->disable_discovery();
1313       ref_processor_cm()->abandon_partial_discovery();
1314       ref_processor_cm()->verify_no_references_recorded();
1315 
1316       // Abandon current iterations of concurrent marking and concurrent
1317       // refinement, if any are in progress. We have to do this before
1318       // wait_until_scan_finished() below.
1319       concurrent_mark()->abort();
1320 
1321       // Make sure we'll choose a new allocation region afterwards.
1322       _allocator->release_mutator_alloc_region();
1323       _allocator->abandon_gc_alloc_regions();
1324       g1_rem_set()->cleanupHRRS();
1325 
1326       // We should call this after we retire any currently active alloc
1327       // regions so that all the ALLOC / RETIRE events are generated
1328       // before the start GC event.
1329       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1330 
1331       // We may have added regions to the current incremental collection
1332       // set between the last GC or pause and now. We need to clear the
1333       // incremental collection set and then start rebuilding it afresh
1334       // after this full GC.
1335       abandon_collection_set(g1_policy()->inc_cset_head());
1336       g1_policy()->clear_incremental_cset();
1337       g1_policy()->stop_incremental_cset_building();
1338 
1339       tear_down_region_sets(false /* free_list_only */);
1340       collector_state()->set_gcs_are_young(true);
1341 
1342       // See the comments in g1CollectedHeap.hpp and
1343       // G1CollectedHeap::ref_processing_init() about
1344       // how reference processing currently works in G1.
1345 
1346       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1347       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1348 
1349       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1350       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1351 
1352       ref_processor_stw()->enable_discovery();
1353       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1354 
1355       // Do collection work
1356       {
1357         HandleMark hm;  // Discard invalid handles created during gc
1358         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1359       }
1360 
1361       assert(num_free_regions() == 0, "we should not have added any free regions");
1362       rebuild_region_sets(false /* free_list_only */);
1363 
1364       // Enqueue any discovered reference objects that have
1365       // not been removed from the discovered lists.
1366       ref_processor_stw()->enqueue_discovered_references();
1367 
1368 #if defined(COMPILER2) || INCLUDE_JVMCI
1369       DerivedPointerTable::update_pointers();
1370 #endif
1371 
1372       MemoryService::track_memory_usage();
1373 
1374       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1375       ref_processor_stw()->verify_no_references_recorded();
1376 
1377       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1378       ClassLoaderDataGraph::purge();
1379       MetaspaceAux::verify_metrics();
1380 
1381       // Note: since we've just done a full GC, concurrent
1382       // marking is no longer active. Therefore we need not
1383       // re-enable reference discovery for the CM ref processor.
1384       // That will be done at the start of the next marking cycle.
1385       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1386       ref_processor_cm()->verify_no_references_recorded();
1387 
1388       reset_gc_time_stamp();
1389       // Since everything potentially moved, we will clear all remembered
1390       // sets, and clear all cards.  Later we will rebuild remembered
1391       // sets. We will also reset the GC time stamps of the regions.
1392       clear_rsets_post_compaction();
1393       check_gc_time_stamps();
1394 
1395       // Resize the heap if necessary.
1396       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1397 
1398       if (_hr_printer.is_active()) {
1399         // We should do this after we potentially resize the heap so
1400         // that all the COMMIT / UNCOMMIT events are generated before
1401         // the end GC event.
1402 
1403         print_hrm_post_compaction();
1404         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1405       }
1406 
1407       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1408       if (hot_card_cache->use_cache()) {
1409         hot_card_cache->reset_card_counts();
1410         hot_card_cache->reset_hot_cache();
1411       }
1412 
1413       // Rebuild remembered sets of all regions.
1414       uint n_workers =
1415         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1416                                                 workers()->active_workers(),
1417                                                 Threads::number_of_non_daemon_threads());
1418       workers()->set_active_workers(n_workers);
1419 
1420       ParRebuildRSTask rebuild_rs_task(this);
1421       workers()->run_task(&rebuild_rs_task);
1422 
1423       // Rebuild the strong code root lists for each region
1424       rebuild_strong_code_roots();
1425 
1426       if (true) { // FIXME
1427         MetaspaceGC::compute_new_size();
1428       }
1429 
1430 #ifdef TRACESPINNING
1431       ParallelTaskTerminator::print_termination_counts();
1432 #endif
1433 
1434       // Discard all rset updates
1435       JavaThread::dirty_card_queue_set().abandon_logs();
1436       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1437 
1438       _young_list->reset_sampled_info();
1439       // At this point there should be no regions in the
1440       // entire heap tagged as young.
1441       assert(check_young_list_empty(true /* check_heap */),
1442              "young list should be empty at this point");
1443 
1444       // Update the number of full collections that have been completed.
1445       increment_old_marking_cycles_completed(false /* concurrent */);
1446 
1447       _hrm.verify_optional();
1448       verify_region_sets_optional();
1449 
1450       verify_after_gc();
1451 
1452       // Clear the previous marking bitmap, if needed for bitmap verification.
1453       // Note we cannot do this when we clear the next marking bitmap in
1454       // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1455       // objects marked during a full GC against the previous bitmap.
1456       // But we need to clear it before calling check_bitmaps below since
1457       // the full GC has compacted objects and updated TAMS but not updated
1458       // the prev bitmap.
1459       if (G1VerifyBitmaps) {
1460         ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1461       }
1462       check_bitmaps("Full GC End");
1463 
1464       // Start a new incremental collection set for the next pause
1465       assert(g1_policy()->collection_set() == NULL, "must be");
1466       g1_policy()->start_incremental_cset_building();
1467 
1468       clear_cset_fast_test();
1469 
1470       _allocator->init_mutator_alloc_region();
1471 
1472       g1_policy()->record_full_collection_end();
1473 
1474       if (G1Log::fine()) {
1475         g1_policy()->print_heap_transition();
1476       }
1477 
1478       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1479       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1480       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1481       // before any GC notifications are raised.
1482       g1mm()->update_sizes();
1483 
1484       gc_epilogue(true);
1485     }
1486 
1487     if (G1Log::finer()) {
1488       g1_policy()->print_detailed_heap_transition(true /* full */);
1489     }
1490 
1491     print_heap_after_gc();
1492     trace_heap_after_gc(gc_tracer);
1493 
1494     post_full_gc_dump(gc_timer);
1495 
1496     gc_timer->register_gc_end();
1497     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1498   }
1499 
1500   return true;
1501 }
1502 
1503 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1504   // do_collection() will return whether it succeeded in performing
1505   // the GC. Currently, there is no facility on the
1506   // do_full_collection() API to notify the caller than the collection
1507   // did not succeed (e.g., because it was locked out by the GC
1508   // locker). So, right now, we'll ignore the return value.
1509   bool dummy = do_collection(true,                /* explicit_gc */
1510                              clear_all_soft_refs,
1511                              0                    /* word_size */);
1512 }
1513 
1514 // This code is mostly copied from TenuredGeneration.
1515 void
1516 G1CollectedHeap::
1517 resize_if_necessary_after_full_collection(size_t word_size) {
1518   // Include the current allocation, if any, and bytes that will be
1519   // pre-allocated to support collections, as "used".
1520   const size_t used_after_gc = used();
1521   const size_t capacity_after_gc = capacity();
1522   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1523 
1524   // This is enforced in arguments.cpp.
1525   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1526          "otherwise the code below doesn't make sense");
1527 
1528   // We don't have floating point command-line arguments
1529   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1530   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1531   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1532   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1533 
1534   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1535   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1536 
1537   // We have to be careful here as these two calculations can overflow
1538   // 32-bit size_t's.
1539   double used_after_gc_d = (double) used_after_gc;
1540   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1541   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1542 
1543   // Let's make sure that they are both under the max heap size, which
1544   // by default will make them fit into a size_t.
1545   double desired_capacity_upper_bound = (double) max_heap_size;
1546   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1547                                     desired_capacity_upper_bound);
1548   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1549                                     desired_capacity_upper_bound);
1550 
1551   // We can now safely turn them into size_t's.
1552   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1553   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1554 
1555   // This assert only makes sense here, before we adjust them
1556   // with respect to the min and max heap size.
1557   assert(minimum_desired_capacity <= maximum_desired_capacity,
1558          "minimum_desired_capacity = " SIZE_FORMAT ", "
1559          "maximum_desired_capacity = " SIZE_FORMAT,
1560          minimum_desired_capacity, maximum_desired_capacity);
1561 
1562   // Should not be greater than the heap max size. No need to adjust
1563   // it with respect to the heap min size as it's a lower bound (i.e.,
1564   // we'll try to make the capacity larger than it, not smaller).
1565   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1566   // Should not be less than the heap min size. No need to adjust it
1567   // with respect to the heap max size as it's an upper bound (i.e.,
1568   // we'll try to make the capacity smaller than it, not greater).
1569   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1570 
1571   if (capacity_after_gc < minimum_desired_capacity) {
1572     // Don't expand unless it's significant
1573     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1574     ergo_verbose4(ErgoHeapSizing,
1575                   "attempt heap expansion",
1576                   ergo_format_reason("capacity lower than "
1577                                      "min desired capacity after Full GC")
1578                   ergo_format_byte("capacity")
1579                   ergo_format_byte("occupancy")
1580                   ergo_format_byte_perc("min desired capacity"),
1581                   capacity_after_gc, used_after_gc,
1582                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1583     expand(expand_bytes);
1584 
1585     // No expansion, now see if we want to shrink
1586   } else if (capacity_after_gc > maximum_desired_capacity) {
1587     // Capacity too large, compute shrinking size
1588     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1589     ergo_verbose4(ErgoHeapSizing,
1590                   "attempt heap shrinking",
1591                   ergo_format_reason("capacity higher than "
1592                                      "max desired capacity after Full GC")
1593                   ergo_format_byte("capacity")
1594                   ergo_format_byte("occupancy")
1595                   ergo_format_byte_perc("max desired capacity"),
1596                   capacity_after_gc, used_after_gc,
1597                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1598     shrink(shrink_bytes);
1599   }
1600 }
1601 
1602 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1603                                                             AllocationContext_t context,
1604                                                             bool do_gc,
1605                                                             bool clear_all_soft_refs,
1606                                                             bool expect_null_mutator_alloc_region,
1607                                                             bool* gc_succeeded) {
1608   *gc_succeeded = true;
1609   // Let's attempt the allocation first.
1610   HeapWord* result =
1611     attempt_allocation_at_safepoint(word_size,
1612                                     context,
1613                                     expect_null_mutator_alloc_region);
1614   if (result != NULL) {
1615     assert(*gc_succeeded, "sanity");
1616     return result;
1617   }
1618 
1619   // In a G1 heap, we're supposed to keep allocation from failing by
1620   // incremental pauses.  Therefore, at least for now, we'll favor
1621   // expansion over collection.  (This might change in the future if we can
1622   // do something smarter than full collection to satisfy a failed alloc.)
1623   result = expand_and_allocate(word_size, context);
1624   if (result != NULL) {
1625     assert(*gc_succeeded, "sanity");
1626     return result;
1627   }
1628 
1629   if (do_gc) {
1630     // Expansion didn't work, we'll try to do a Full GC.
1631     *gc_succeeded = do_collection(false, /* explicit_gc */
1632                                   clear_all_soft_refs,
1633                                   word_size);
1634   }
1635 
1636   return NULL;
1637 }
1638 
1639 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1640                                                      AllocationContext_t context,
1641                                                      bool* succeeded) {
1642   assert_at_safepoint(true /* should_be_vm_thread */);
1643 
1644   // Attempts to allocate followed by Full GC.
1645   HeapWord* result =
1646     satisfy_failed_allocation_helper(word_size,
1647                                      context,
1648                                      true,  /* do_gc */
1649                                      false, /* clear_all_soft_refs */
1650                                      false, /* expect_null_mutator_alloc_region */
1651                                      succeeded);
1652 
1653   if (result != NULL || !*succeeded) {
1654     return result;
1655   }
1656 
1657   // Attempts to allocate followed by Full GC that will collect all soft references.
1658   result = satisfy_failed_allocation_helper(word_size,
1659                                             context,
1660                                             true, /* do_gc */
1661                                             true, /* clear_all_soft_refs */
1662                                             true, /* expect_null_mutator_alloc_region */
1663                                             succeeded);
1664 
1665   if (result != NULL || !*succeeded) {
1666     return result;
1667   }
1668 
1669   // Attempts to allocate, no GC
1670   result = satisfy_failed_allocation_helper(word_size,
1671                                             context,
1672                                             false, /* do_gc */
1673                                             false, /* clear_all_soft_refs */
1674                                             true,  /* expect_null_mutator_alloc_region */
1675                                             succeeded);
1676 
1677   if (result != NULL) {
1678     assert(*succeeded, "sanity");
1679     return result;
1680   }
1681 
1682   assert(!collector_policy()->should_clear_all_soft_refs(),
1683          "Flag should have been handled and cleared prior to this point");
1684 
1685   // What else?  We might try synchronous finalization later.  If the total
1686   // space available is large enough for the allocation, then a more
1687   // complete compaction phase than we've tried so far might be
1688   // appropriate.
1689   assert(*succeeded, "sanity");
1690   return NULL;
1691 }
1692 
1693 // Attempting to expand the heap sufficiently
1694 // to support an allocation of the given "word_size".  If
1695 // successful, perform the allocation and return the address of the
1696 // allocated block, or else "NULL".
1697 
1698 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1699   assert_at_safepoint(true /* should_be_vm_thread */);
1700 
1701   verify_region_sets_optional();
1702 
1703   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1704   ergo_verbose1(ErgoHeapSizing,
1705                 "attempt heap expansion",
1706                 ergo_format_reason("allocation request failed")
1707                 ergo_format_byte("allocation request"),
1708                 word_size * HeapWordSize);
1709   if (expand(expand_bytes)) {
1710     _hrm.verify_optional();
1711     verify_region_sets_optional();
1712     return attempt_allocation_at_safepoint(word_size,
1713                                            context,
1714                                            false /* expect_null_mutator_alloc_region */);
1715   }
1716   return NULL;
1717 }
1718 
1719 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1720   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1721   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1722                                        HeapRegion::GrainBytes);
1723   ergo_verbose2(ErgoHeapSizing,
1724                 "expand the heap",
1725                 ergo_format_byte("requested expansion amount")
1726                 ergo_format_byte("attempted expansion amount"),
1727                 expand_bytes, aligned_expand_bytes);
1728 
1729   if (is_maximal_no_gc()) {
1730     ergo_verbose0(ErgoHeapSizing,
1731                       "did not expand the heap",
1732                       ergo_format_reason("heap already fully expanded"));
1733     return false;
1734   }
1735 
1736   double expand_heap_start_time_sec = os::elapsedTime();
1737   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1738   assert(regions_to_expand > 0, "Must expand by at least one region");
1739 
1740   uint expanded_by = _hrm.expand_by(regions_to_expand);
1741   if (expand_time_ms != NULL) {
1742     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1743   }
1744 
1745   if (expanded_by > 0) {
1746     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1747     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1748     g1_policy()->record_new_heap_size(num_regions());
1749   } else {
1750     ergo_verbose0(ErgoHeapSizing,
1751                   "did not expand the heap",
1752                   ergo_format_reason("heap expansion operation failed"));
1753     // The expansion of the virtual storage space was unsuccessful.
1754     // Let's see if it was because we ran out of swap.
1755     if (G1ExitOnExpansionFailure &&
1756         _hrm.available() >= regions_to_expand) {
1757       // We had head room...
1758       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1759     }
1760   }
1761   return regions_to_expand > 0;
1762 }
1763 
1764 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1765   size_t aligned_shrink_bytes =
1766     ReservedSpace::page_align_size_down(shrink_bytes);
1767   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1768                                          HeapRegion::GrainBytes);
1769   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1770 
1771   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1772   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1773 
1774   ergo_verbose3(ErgoHeapSizing,
1775                 "shrink the heap",
1776                 ergo_format_byte("requested shrinking amount")
1777                 ergo_format_byte("aligned shrinking amount")
1778                 ergo_format_byte("attempted shrinking amount"),
1779                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1780   if (num_regions_removed > 0) {
1781     g1_policy()->record_new_heap_size(num_regions());
1782   } else {
1783     ergo_verbose0(ErgoHeapSizing,
1784                   "did not shrink the heap",
1785                   ergo_format_reason("heap shrinking operation failed"));
1786   }
1787 }
1788 
1789 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1790   verify_region_sets_optional();
1791 
1792   // We should only reach here at the end of a Full GC which means we
1793   // should not not be holding to any GC alloc regions. The method
1794   // below will make sure of that and do any remaining clean up.
1795   _allocator->abandon_gc_alloc_regions();
1796 
1797   // Instead of tearing down / rebuilding the free lists here, we
1798   // could instead use the remove_all_pending() method on free_list to
1799   // remove only the ones that we need to remove.
1800   tear_down_region_sets(true /* free_list_only */);
1801   shrink_helper(shrink_bytes);
1802   rebuild_region_sets(true /* free_list_only */);
1803 
1804   _hrm.verify_optional();
1805   verify_region_sets_optional();
1806 }
1807 
1808 // Public methods.
1809 
1810 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1811   CollectedHeap(),
1812   _g1_policy(policy_),
1813   _dirty_card_queue_set(false),
1814   _into_cset_dirty_card_queue_set(false),
1815   _is_alive_closure_cm(this),
1816   _is_alive_closure_stw(this),
1817   _ref_processor_cm(NULL),
1818   _ref_processor_stw(NULL),
1819   _bot_shared(NULL),
1820   _cg1r(NULL),
1821   _g1mm(NULL),
1822   _refine_cte_cl(NULL),
1823   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1824   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1825   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1826   _humongous_reclaim_candidates(),
1827   _has_humongous_reclaim_candidates(false),
1828   _archive_allocator(NULL),
1829   _free_regions_coming(false),
1830   _young_list(new YoungList(this)),
1831   _gc_time_stamp(0),
1832   _summary_bytes_used(0),
1833   _survivor_evac_stats(YoungPLABSize, PLABWeight),
1834   _old_evac_stats(OldPLABSize, PLABWeight),
1835   _expand_heap_after_alloc_failure(true),
1836   _old_marking_cycles_started(0),
1837   _old_marking_cycles_completed(0),
1838   _heap_summary_sent(false),
1839   _in_cset_fast_test(),
1840   _dirty_cards_region_list(NULL),
1841   _worker_cset_start_region(NULL),
1842   _worker_cset_start_region_time_stamp(NULL),
1843   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1844   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1845   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1846   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1847 
1848   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1849                           /* are_GC_task_threads */true,
1850                           /* are_ConcurrentGC_threads */false);
1851   _workers->initialize_workers();
1852 
1853   _allocator = G1Allocator::create_allocator(this);
1854   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1855 
1856   // Override the default _filler_array_max_size so that no humongous filler
1857   // objects are created.
1858   _filler_array_max_size = _humongous_object_threshold_in_words;
1859 
1860   uint n_queues = ParallelGCThreads;
1861   _task_queues = new RefToScanQueueSet(n_queues);
1862 
1863   uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1864   assert(n_rem_sets > 0, "Invariant.");
1865 
1866   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1867   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1868   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1869 
1870   for (uint i = 0; i < n_queues; i++) {
1871     RefToScanQueue* q = new RefToScanQueue();
1872     q->initialize();
1873     _task_queues->register_queue(i, q);
1874     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1875   }
1876   clear_cset_start_regions();
1877 
1878   // Initialize the G1EvacuationFailureALot counters and flags.
1879   NOT_PRODUCT(reset_evacuation_should_fail();)
1880 
1881   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1882 }
1883 
1884 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1885                                                                  size_t size,
1886                                                                  size_t translation_factor) {
1887   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1888   // Allocate a new reserved space, preferring to use large pages.
1889   ReservedSpace rs(size, preferred_page_size);
1890   G1RegionToSpaceMapper* result  =
1891     G1RegionToSpaceMapper::create_mapper(rs,
1892                                          size,
1893                                          rs.alignment(),
1894                                          HeapRegion::GrainBytes,
1895                                          translation_factor,
1896                                          mtGC);
1897   if (TracePageSizes) {
1898     gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1899                            description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1900   }
1901   return result;
1902 }
1903 
1904 jint G1CollectedHeap::initialize() {
1905   CollectedHeap::pre_initialize();
1906   os::enable_vtime();
1907 
1908   G1Log::init();
1909 
1910   // Necessary to satisfy locking discipline assertions.
1911 
1912   MutexLocker x(Heap_lock);
1913 
1914   // We have to initialize the printer before committing the heap, as
1915   // it will be used then.
1916   _hr_printer.set_active(G1PrintHeapRegions);
1917 
1918   // While there are no constraints in the GC code that HeapWordSize
1919   // be any particular value, there are multiple other areas in the
1920   // system which believe this to be true (e.g. oop->object_size in some
1921   // cases incorrectly returns the size in wordSize units rather than
1922   // HeapWordSize).
1923   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1924 
1925   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1926   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1927   size_t heap_alignment = collector_policy()->heap_alignment();
1928 
1929   // Ensure that the sizes are properly aligned.
1930   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1931   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1932   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1933 
1934   _refine_cte_cl = new RefineCardTableEntryClosure();
1935 
1936   jint ecode = JNI_OK;
1937   _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1938   if (_cg1r == NULL) {
1939     return ecode;
1940   }
1941 
1942   // Reserve the maximum.
1943 
1944   // When compressed oops are enabled, the preferred heap base
1945   // is calculated by subtracting the requested size from the
1946   // 32Gb boundary and using the result as the base address for
1947   // heap reservation. If the requested size is not aligned to
1948   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1949   // into the ReservedHeapSpace constructor) then the actual
1950   // base of the reserved heap may end up differing from the
1951   // address that was requested (i.e. the preferred heap base).
1952   // If this happens then we could end up using a non-optimal
1953   // compressed oops mode.
1954 
1955   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1956                                                  heap_alignment);
1957 
1958   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1959 
1960   // Create the barrier set for the entire reserved region.
1961   G1SATBCardTableLoggingModRefBS* bs
1962     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1963   bs->initialize();
1964   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1965   set_barrier_set(bs);
1966 
1967   // Also create a G1 rem set.
1968   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1969 
1970   // Carve out the G1 part of the heap.
1971 
1972   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1973   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1974   G1RegionToSpaceMapper* heap_storage =
1975     G1RegionToSpaceMapper::create_mapper(g1_rs,
1976                                          g1_rs.size(),
1977                                          page_size,
1978                                          HeapRegion::GrainBytes,
1979                                          1,
1980                                          mtJavaHeap);
1981   os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1982                        max_byte_size, page_size,
1983                        heap_rs.base(),
1984                        heap_rs.size());
1985   heap_storage->set_mapping_changed_listener(&_listener);
1986 
1987   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1988   G1RegionToSpaceMapper* bot_storage =
1989     create_aux_memory_mapper("Block offset table",
1990                              G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1991                              G1BlockOffsetSharedArray::heap_map_factor());
1992 
1993   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1994   G1RegionToSpaceMapper* cardtable_storage =
1995     create_aux_memory_mapper("Card table",
1996                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1997                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
1998 
1999   G1RegionToSpaceMapper* card_counts_storage =
2000     create_aux_memory_mapper("Card counts table",
2001                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2002                              G1CardCounts::heap_map_factor());
2003 
2004   size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2005   G1RegionToSpaceMapper* prev_bitmap_storage =
2006     create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2007   G1RegionToSpaceMapper* next_bitmap_storage =
2008     create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2009 
2010   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2011   g1_barrier_set()->initialize(cardtable_storage);
2012    // Do later initialization work for concurrent refinement.
2013   _cg1r->init(card_counts_storage);
2014 
2015   // 6843694 - ensure that the maximum region index can fit
2016   // in the remembered set structures.
2017   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2018   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2019 
2020   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2021   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2022   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2023             "too many cards per region");
2024 
2025   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2026 
2027   _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2028 
2029   {
2030     HeapWord* start = _hrm.reserved().start();
2031     HeapWord* end = _hrm.reserved().end();
2032     size_t granularity = HeapRegion::GrainBytes;
2033 
2034     _in_cset_fast_test.initialize(start, end, granularity);
2035     _humongous_reclaim_candidates.initialize(start, end, granularity);
2036   }
2037 
2038   // Create the ConcurrentMark data structure and thread.
2039   // (Must do this late, so that "max_regions" is defined.)
2040   _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2041   if (_cm == NULL || !_cm->completed_initialization()) {
2042     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2043     return JNI_ENOMEM;
2044   }
2045   _cmThread = _cm->cmThread();
2046 
2047   // Initialize the from_card cache structure of HeapRegionRemSet.
2048   HeapRegionRemSet::init_heap(max_regions());
2049 
2050   // Now expand into the initial heap size.
2051   if (!expand(init_byte_size)) {
2052     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2053     return JNI_ENOMEM;
2054   }
2055 
2056   // Perform any initialization actions delegated to the policy.
2057   g1_policy()->init();
2058 
2059   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2060                                                SATB_Q_FL_lock,
2061                                                G1SATBProcessCompletedThreshold,
2062                                                Shared_SATB_Q_lock);
2063 
2064   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2065                                                 DirtyCardQ_CBL_mon,
2066                                                 DirtyCardQ_FL_lock,
2067                                                 concurrent_g1_refine()->yellow_zone(),
2068                                                 concurrent_g1_refine()->red_zone(),
2069                                                 Shared_DirtyCardQ_lock);
2070 
2071   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2072                                     DirtyCardQ_CBL_mon,
2073                                     DirtyCardQ_FL_lock,
2074                                     -1, // never trigger processing
2075                                     -1, // no limit on length
2076                                     Shared_DirtyCardQ_lock,
2077                                     &JavaThread::dirty_card_queue_set());
2078 
2079   // Initialize the card queue set used to hold cards containing
2080   // references into the collection set.
2081   _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2082                                              DirtyCardQ_CBL_mon,
2083                                              DirtyCardQ_FL_lock,
2084                                              -1, // never trigger processing
2085                                              -1, // no limit on length
2086                                              Shared_DirtyCardQ_lock,
2087                                              &JavaThread::dirty_card_queue_set());
2088 
2089   // Here we allocate the dummy HeapRegion that is required by the
2090   // G1AllocRegion class.
2091   HeapRegion* dummy_region = _hrm.get_dummy_region();
2092 
2093   // We'll re-use the same region whether the alloc region will
2094   // require BOT updates or not and, if it doesn't, then a non-young
2095   // region will complain that it cannot support allocations without
2096   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2097   dummy_region->set_eden();
2098   // Make sure it's full.
2099   dummy_region->set_top(dummy_region->end());
2100   G1AllocRegion::setup(this, dummy_region);
2101 
2102   _allocator->init_mutator_alloc_region();
2103 
2104   // Do create of the monitoring and management support so that
2105   // values in the heap have been properly initialized.
2106   _g1mm = new G1MonitoringSupport(this);
2107 
2108   G1StringDedup::initialize();
2109 
2110   _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2111   for (uint i = 0; i < ParallelGCThreads; i++) {
2112     new (&_preserved_objs[i]) OopAndMarkOopStack();
2113   }
2114 
2115   return JNI_OK;
2116 }
2117 
2118 void G1CollectedHeap::stop() {
2119   // Stop all concurrent threads. We do this to make sure these threads
2120   // do not continue to execute and access resources (e.g. gclog_or_tty)
2121   // that are destroyed during shutdown.
2122   _cg1r->stop();
2123   _cmThread->stop();
2124   if (G1StringDedup::is_enabled()) {
2125     G1StringDedup::stop();
2126   }
2127 }
2128 
2129 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2130   return HeapRegion::max_region_size();
2131 }
2132 
2133 void G1CollectedHeap::post_initialize() {
2134   CollectedHeap::post_initialize();
2135   ref_processing_init();
2136 }
2137 
2138 void G1CollectedHeap::ref_processing_init() {
2139   // Reference processing in G1 currently works as follows:
2140   //
2141   // * There are two reference processor instances. One is
2142   //   used to record and process discovered references
2143   //   during concurrent marking; the other is used to
2144   //   record and process references during STW pauses
2145   //   (both full and incremental).
2146   // * Both ref processors need to 'span' the entire heap as
2147   //   the regions in the collection set may be dotted around.
2148   //
2149   // * For the concurrent marking ref processor:
2150   //   * Reference discovery is enabled at initial marking.
2151   //   * Reference discovery is disabled and the discovered
2152   //     references processed etc during remarking.
2153   //   * Reference discovery is MT (see below).
2154   //   * Reference discovery requires a barrier (see below).
2155   //   * Reference processing may or may not be MT
2156   //     (depending on the value of ParallelRefProcEnabled
2157   //     and ParallelGCThreads).
2158   //   * A full GC disables reference discovery by the CM
2159   //     ref processor and abandons any entries on it's
2160   //     discovered lists.
2161   //
2162   // * For the STW processor:
2163   //   * Non MT discovery is enabled at the start of a full GC.
2164   //   * Processing and enqueueing during a full GC is non-MT.
2165   //   * During a full GC, references are processed after marking.
2166   //
2167   //   * Discovery (may or may not be MT) is enabled at the start
2168   //     of an incremental evacuation pause.
2169   //   * References are processed near the end of a STW evacuation pause.
2170   //   * For both types of GC:
2171   //     * Discovery is atomic - i.e. not concurrent.
2172   //     * Reference discovery will not need a barrier.
2173 
2174   MemRegion mr = reserved_region();
2175 
2176   // Concurrent Mark ref processor
2177   _ref_processor_cm =
2178     new ReferenceProcessor(mr,    // span
2179                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2180                                 // mt processing
2181                            ParallelGCThreads,
2182                                 // degree of mt processing
2183                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2184                                 // mt discovery
2185                            MAX2(ParallelGCThreads, ConcGCThreads),
2186                                 // degree of mt discovery
2187                            false,
2188                                 // Reference discovery is not atomic
2189                            &_is_alive_closure_cm);
2190                                 // is alive closure
2191                                 // (for efficiency/performance)
2192 
2193   // STW ref processor
2194   _ref_processor_stw =
2195     new ReferenceProcessor(mr,    // span
2196                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2197                                 // mt processing
2198                            ParallelGCThreads,
2199                                 // degree of mt processing
2200                            (ParallelGCThreads > 1),
2201                                 // mt discovery
2202                            ParallelGCThreads,
2203                                 // degree of mt discovery
2204                            true,
2205                                 // Reference discovery is atomic
2206                            &_is_alive_closure_stw);
2207                                 // is alive closure
2208                                 // (for efficiency/performance)
2209 }
2210 
2211 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2212   return g1_policy();
2213 }
2214 
2215 size_t G1CollectedHeap::capacity() const {
2216   return _hrm.length() * HeapRegion::GrainBytes;
2217 }
2218 
2219 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2220   assert(!hr->is_continues_humongous(), "pre-condition");
2221   hr->reset_gc_time_stamp();
2222   if (hr->is_starts_humongous()) {
2223     uint first_index = hr->hrm_index() + 1;
2224     uint last_index = hr->last_hc_index();
2225     for (uint i = first_index; i < last_index; i += 1) {
2226       HeapRegion* chr = region_at(i);
2227       assert(chr->is_continues_humongous(), "sanity");
2228       chr->reset_gc_time_stamp();
2229     }
2230   }
2231 }
2232 
2233 #ifndef PRODUCT
2234 
2235 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2236 private:
2237   unsigned _gc_time_stamp;
2238   bool _failures;
2239 
2240 public:
2241   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2242     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2243 
2244   virtual bool doHeapRegion(HeapRegion* hr) {
2245     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2246     if (_gc_time_stamp != region_gc_time_stamp) {
2247       gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2248                              "expected %d", HR_FORMAT_PARAMS(hr),
2249                              region_gc_time_stamp, _gc_time_stamp);
2250       _failures = true;
2251     }
2252     return false;
2253   }
2254 
2255   bool failures() { return _failures; }
2256 };
2257 
2258 void G1CollectedHeap::check_gc_time_stamps() {
2259   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2260   heap_region_iterate(&cl);
2261   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2262 }
2263 #endif // PRODUCT
2264 
2265 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2266   _cg1r->hot_card_cache()->drain(cl, worker_i);
2267 }
2268 
2269 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2270   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2271   size_t n_completed_buffers = 0;
2272   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2273     n_completed_buffers++;
2274   }
2275   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2276   dcqs.clear_n_completed_buffers();
2277   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2278 }
2279 
2280 // Computes the sum of the storage used by the various regions.
2281 size_t G1CollectedHeap::used() const {
2282   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2283   if (_archive_allocator != NULL) {
2284     result += _archive_allocator->used();
2285   }
2286   return result;
2287 }
2288 
2289 size_t G1CollectedHeap::used_unlocked() const {
2290   return _summary_bytes_used;
2291 }
2292 
2293 class SumUsedClosure: public HeapRegionClosure {
2294   size_t _used;
2295 public:
2296   SumUsedClosure() : _used(0) {}
2297   bool doHeapRegion(HeapRegion* r) {
2298     if (!r->is_continues_humongous()) {
2299       _used += r->used();
2300     }
2301     return false;
2302   }
2303   size_t result() { return _used; }
2304 };
2305 
2306 size_t G1CollectedHeap::recalculate_used() const {
2307   double recalculate_used_start = os::elapsedTime();
2308 
2309   SumUsedClosure blk;
2310   heap_region_iterate(&blk);
2311 
2312   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2313   return blk.result();
2314 }
2315 
2316 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2317   switch (cause) {
2318     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2319     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2320     case GCCause::_dcmd_gc_run:             return ExplicitGCInvokesConcurrent;
2321     case GCCause::_g1_humongous_allocation: return true;
2322     case GCCause::_update_allocation_context_stats_inc: return true;
2323     case GCCause::_wb_conc_mark:            return true;
2324     default:                                return false;
2325   }
2326 }
2327 
2328 #ifndef PRODUCT
2329 void G1CollectedHeap::allocate_dummy_regions() {
2330   // Let's fill up most of the region
2331   size_t word_size = HeapRegion::GrainWords - 1024;
2332   // And as a result the region we'll allocate will be humongous.
2333   guarantee(is_humongous(word_size), "sanity");
2334 
2335   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2336     // Let's use the existing mechanism for the allocation
2337     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2338                                                  AllocationContext::system());
2339     if (dummy_obj != NULL) {
2340       MemRegion mr(dummy_obj, word_size);
2341       CollectedHeap::fill_with_object(mr);
2342     } else {
2343       // If we can't allocate once, we probably cannot allocate
2344       // again. Let's get out of the loop.
2345       break;
2346     }
2347   }
2348 }
2349 #endif // !PRODUCT
2350 
2351 void G1CollectedHeap::increment_old_marking_cycles_started() {
2352   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2353          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2354          "Wrong marking cycle count (started: %d, completed: %d)",
2355          _old_marking_cycles_started, _old_marking_cycles_completed);
2356 
2357   _old_marking_cycles_started++;
2358 }
2359 
2360 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2361   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2362 
2363   // We assume that if concurrent == true, then the caller is a
2364   // concurrent thread that was joined the Suspendible Thread
2365   // Set. If there's ever a cheap way to check this, we should add an
2366   // assert here.
2367 
2368   // Given that this method is called at the end of a Full GC or of a
2369   // concurrent cycle, and those can be nested (i.e., a Full GC can
2370   // interrupt a concurrent cycle), the number of full collections
2371   // completed should be either one (in the case where there was no
2372   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2373   // behind the number of full collections started.
2374 
2375   // This is the case for the inner caller, i.e. a Full GC.
2376   assert(concurrent ||
2377          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2378          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2379          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2380          "is inconsistent with _old_marking_cycles_completed = %u",
2381          _old_marking_cycles_started, _old_marking_cycles_completed);
2382 
2383   // This is the case for the outer caller, i.e. the concurrent cycle.
2384   assert(!concurrent ||
2385          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2386          "for outer caller (concurrent cycle): "
2387          "_old_marking_cycles_started = %u "
2388          "is inconsistent with _old_marking_cycles_completed = %u",
2389          _old_marking_cycles_started, _old_marking_cycles_completed);
2390 
2391   _old_marking_cycles_completed += 1;
2392 
2393   // We need to clear the "in_progress" flag in the CM thread before
2394   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2395   // is set) so that if a waiter requests another System.gc() it doesn't
2396   // incorrectly see that a marking cycle is still in progress.
2397   if (concurrent) {
2398     _cmThread->set_idle();
2399   }
2400 
2401   // This notify_all() will ensure that a thread that called
2402   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2403   // and it's waiting for a full GC to finish will be woken up. It is
2404   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2405   FullGCCount_lock->notify_all();
2406 }
2407 
2408 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2409   GCIdMarkAndRestore conc_gc_id_mark;
2410   collector_state()->set_concurrent_cycle_started(true);
2411   _gc_timer_cm->register_gc_start(start_time);
2412 
2413   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2414   trace_heap_before_gc(_gc_tracer_cm);
2415   _cmThread->set_gc_id(GCId::current());
2416 }
2417 
2418 void G1CollectedHeap::register_concurrent_cycle_end() {
2419   if (collector_state()->concurrent_cycle_started()) {
2420     GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2421     if (_cm->has_aborted()) {
2422       _gc_tracer_cm->report_concurrent_mode_failure();
2423     }
2424 
2425     _gc_timer_cm->register_gc_end();
2426     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2427 
2428     // Clear state variables to prepare for the next concurrent cycle.
2429      collector_state()->set_concurrent_cycle_started(false);
2430     _heap_summary_sent = false;
2431   }
2432 }
2433 
2434 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2435   if (collector_state()->concurrent_cycle_started()) {
2436     // This function can be called when:
2437     //  the cleanup pause is run
2438     //  the concurrent cycle is aborted before the cleanup pause.
2439     //  the concurrent cycle is aborted after the cleanup pause,
2440     //   but before the concurrent cycle end has been registered.
2441     // Make sure that we only send the heap information once.
2442     if (!_heap_summary_sent) {
2443       GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2444       trace_heap_after_gc(_gc_tracer_cm);
2445       _heap_summary_sent = true;
2446     }
2447   }
2448 }
2449 
2450 void G1CollectedHeap::collect(GCCause::Cause cause) {
2451   assert_heap_not_locked();
2452 
2453   uint gc_count_before;
2454   uint old_marking_count_before;
2455   uint full_gc_count_before;
2456   bool retry_gc;
2457 
2458   do {
2459     retry_gc = false;
2460 
2461     {
2462       MutexLocker ml(Heap_lock);
2463 
2464       // Read the GC count while holding the Heap_lock
2465       gc_count_before = total_collections();
2466       full_gc_count_before = total_full_collections();
2467       old_marking_count_before = _old_marking_cycles_started;
2468     }
2469 
2470     if (should_do_concurrent_full_gc(cause)) {
2471       // Schedule an initial-mark evacuation pause that will start a
2472       // concurrent cycle. We're setting word_size to 0 which means that
2473       // we are not requesting a post-GC allocation.
2474       VM_G1IncCollectionPause op(gc_count_before,
2475                                  0,     /* word_size */
2476                                  true,  /* should_initiate_conc_mark */
2477                                  g1_policy()->max_pause_time_ms(),
2478                                  cause);
2479       op.set_allocation_context(AllocationContext::current());
2480 
2481       VMThread::execute(&op);
2482       if (!op.pause_succeeded()) {
2483         if (old_marking_count_before == _old_marking_cycles_started) {
2484           retry_gc = op.should_retry_gc();
2485         } else {
2486           // A Full GC happened while we were trying to schedule the
2487           // initial-mark GC. No point in starting a new cycle given
2488           // that the whole heap was collected anyway.
2489         }
2490 
2491         if (retry_gc) {
2492           if (GC_locker::is_active_and_needs_gc()) {
2493             GC_locker::stall_until_clear();
2494           }
2495         }
2496       }
2497     } else {
2498       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2499           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2500 
2501         // Schedule a standard evacuation pause. We're setting word_size
2502         // to 0 which means that we are not requesting a post-GC allocation.
2503         VM_G1IncCollectionPause op(gc_count_before,
2504                                    0,     /* word_size */
2505                                    false, /* should_initiate_conc_mark */
2506                                    g1_policy()->max_pause_time_ms(),
2507                                    cause);
2508         VMThread::execute(&op);
2509       } else {
2510         // Schedule a Full GC.
2511         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2512         VMThread::execute(&op);
2513       }
2514     }
2515   } while (retry_gc);
2516 }
2517 
2518 bool G1CollectedHeap::is_in(const void* p) const {
2519   if (_hrm.reserved().contains(p)) {
2520     // Given that we know that p is in the reserved space,
2521     // heap_region_containing_raw() should successfully
2522     // return the containing region.
2523     HeapRegion* hr = heap_region_containing_raw(p);
2524     return hr->is_in(p);
2525   } else {
2526     return false;
2527   }
2528 }
2529 
2530 #ifdef ASSERT
2531 bool G1CollectedHeap::is_in_exact(const void* p) const {
2532   bool contains = reserved_region().contains(p);
2533   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2534   if (contains && available) {
2535     return true;
2536   } else {
2537     return false;
2538   }
2539 }
2540 #endif
2541 
2542 bool G1CollectedHeap::obj_in_cs(oop obj) {
2543   HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2544   return r != NULL && r->in_collection_set();
2545 }
2546 
2547 // Iteration functions.
2548 
2549 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2550 
2551 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2552   ExtendedOopClosure* _cl;
2553 public:
2554   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2555   bool doHeapRegion(HeapRegion* r) {
2556     if (!r->is_continues_humongous()) {
2557       r->oop_iterate(_cl);
2558     }
2559     return false;
2560   }
2561 };
2562 
2563 // Iterates an ObjectClosure over all objects within a HeapRegion.
2564 
2565 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2566   ObjectClosure* _cl;
2567 public:
2568   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2569   bool doHeapRegion(HeapRegion* r) {
2570     if (!r->is_continues_humongous()) {
2571       r->object_iterate(_cl);
2572     }
2573     return false;
2574   }
2575 };
2576 
2577 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2578   IterateObjectClosureRegionClosure blk(cl);
2579   heap_region_iterate(&blk);
2580 }
2581 
2582 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2583   _hrm.iterate(cl);
2584 }
2585 
2586 void
2587 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2588                                          uint worker_id,
2589                                          HeapRegionClaimer *hrclaimer,
2590                                          bool concurrent) const {
2591   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2592 }
2593 
2594 // Clear the cached CSet starting regions and (more importantly)
2595 // the time stamps. Called when we reset the GC time stamp.
2596 void G1CollectedHeap::clear_cset_start_regions() {
2597   assert(_worker_cset_start_region != NULL, "sanity");
2598   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2599 
2600   for (uint i = 0; i < ParallelGCThreads; i++) {
2601     _worker_cset_start_region[i] = NULL;
2602     _worker_cset_start_region_time_stamp[i] = 0;
2603   }
2604 }
2605 
2606 // Given the id of a worker, obtain or calculate a suitable
2607 // starting region for iterating over the current collection set.
2608 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2609   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2610 
2611   HeapRegion* result = NULL;
2612   unsigned gc_time_stamp = get_gc_time_stamp();
2613 
2614   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2615     // Cached starting region for current worker was set
2616     // during the current pause - so it's valid.
2617     // Note: the cached starting heap region may be NULL
2618     // (when the collection set is empty).
2619     result = _worker_cset_start_region[worker_i];
2620     assert(result == NULL || result->in_collection_set(), "sanity");
2621     return result;
2622   }
2623 
2624   // The cached entry was not valid so let's calculate
2625   // a suitable starting heap region for this worker.
2626 
2627   // We want the parallel threads to start their collection
2628   // set iteration at different collection set regions to
2629   // avoid contention.
2630   // If we have:
2631   //          n collection set regions
2632   //          p threads
2633   // Then thread t will start at region floor ((t * n) / p)
2634 
2635   result = g1_policy()->collection_set();
2636   uint cs_size = g1_policy()->cset_region_length();
2637   uint active_workers = workers()->active_workers();
2638 
2639   uint end_ind   = (cs_size * worker_i) / active_workers;
2640   uint start_ind = 0;
2641 
2642   if (worker_i > 0 &&
2643       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2644     // Previous workers starting region is valid
2645     // so let's iterate from there
2646     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2647     result = _worker_cset_start_region[worker_i - 1];
2648   }
2649 
2650   for (uint i = start_ind; i < end_ind; i++) {
2651     result = result->next_in_collection_set();
2652   }
2653 
2654   // Note: the calculated starting heap region may be NULL
2655   // (when the collection set is empty).
2656   assert(result == NULL || result->in_collection_set(), "sanity");
2657   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2658          "should be updated only once per pause");
2659   _worker_cset_start_region[worker_i] = result;
2660   OrderAccess::storestore();
2661   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2662   return result;
2663 }
2664 
2665 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2666   HeapRegion* r = g1_policy()->collection_set();
2667   while (r != NULL) {
2668     HeapRegion* next = r->next_in_collection_set();
2669     if (cl->doHeapRegion(r)) {
2670       cl->incomplete();
2671       return;
2672     }
2673     r = next;
2674   }
2675 }
2676 
2677 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2678                                                   HeapRegionClosure *cl) {
2679   if (r == NULL) {
2680     // The CSet is empty so there's nothing to do.
2681     return;
2682   }
2683 
2684   assert(r->in_collection_set(),
2685          "Start region must be a member of the collection set.");
2686   HeapRegion* cur = r;
2687   while (cur != NULL) {
2688     HeapRegion* next = cur->next_in_collection_set();
2689     if (cl->doHeapRegion(cur) && false) {
2690       cl->incomplete();
2691       return;
2692     }
2693     cur = next;
2694   }
2695   cur = g1_policy()->collection_set();
2696   while (cur != r) {
2697     HeapRegion* next = cur->next_in_collection_set();
2698     if (cl->doHeapRegion(cur) && false) {
2699       cl->incomplete();
2700       return;
2701     }
2702     cur = next;
2703   }
2704 }
2705 
2706 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2707   HeapRegion* result = _hrm.next_region_in_heap(from);
2708   while (result != NULL && result->is_pinned()) {
2709     result = _hrm.next_region_in_heap(result);
2710   }
2711   return result;
2712 }
2713 
2714 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2715   HeapRegion* hr = heap_region_containing(addr);
2716   return hr->block_start(addr);
2717 }
2718 
2719 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2720   HeapRegion* hr = heap_region_containing(addr);
2721   return hr->block_size(addr);
2722 }
2723 
2724 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2725   HeapRegion* hr = heap_region_containing(addr);
2726   return hr->block_is_obj(addr);
2727 }
2728 
2729 bool G1CollectedHeap::supports_tlab_allocation() const {
2730   return true;
2731 }
2732 
2733 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2734   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2735 }
2736 
2737 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2738   return young_list()->eden_used_bytes();
2739 }
2740 
2741 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2742 // must be equal to the humongous object limit.
2743 size_t G1CollectedHeap::max_tlab_size() const {
2744   return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2745 }
2746 
2747 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2748   AllocationContext_t context = AllocationContext::current();
2749   return _allocator->unsafe_max_tlab_alloc(context);
2750 }
2751 
2752 size_t G1CollectedHeap::max_capacity() const {
2753   return _hrm.reserved().byte_size();
2754 }
2755 
2756 jlong G1CollectedHeap::millis_since_last_gc() {
2757   // assert(false, "NYI");
2758   return 0;
2759 }
2760 
2761 void G1CollectedHeap::prepare_for_verify() {
2762   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2763     ensure_parsability(false);
2764   }
2765   g1_rem_set()->prepare_for_verify();
2766 }
2767 
2768 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2769                                               VerifyOption vo) {
2770   switch (vo) {
2771   case VerifyOption_G1UsePrevMarking:
2772     return hr->obj_allocated_since_prev_marking(obj);
2773   case VerifyOption_G1UseNextMarking:
2774     return hr->obj_allocated_since_next_marking(obj);
2775   case VerifyOption_G1UseMarkWord:
2776     return false;
2777   default:
2778     ShouldNotReachHere();
2779   }
2780   return false; // keep some compilers happy
2781 }
2782 
2783 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2784   switch (vo) {
2785   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2786   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2787   case VerifyOption_G1UseMarkWord:    return NULL;
2788   default:                            ShouldNotReachHere();
2789   }
2790   return NULL; // keep some compilers happy
2791 }
2792 
2793 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2794   switch (vo) {
2795   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2796   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2797   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
2798   default:                            ShouldNotReachHere();
2799   }
2800   return false; // keep some compilers happy
2801 }
2802 
2803 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2804   switch (vo) {
2805   case VerifyOption_G1UsePrevMarking: return "PTAMS";
2806   case VerifyOption_G1UseNextMarking: return "NTAMS";
2807   case VerifyOption_G1UseMarkWord:    return "NONE";
2808   default:                            ShouldNotReachHere();
2809   }
2810   return NULL; // keep some compilers happy
2811 }
2812 
2813 class VerifyRootsClosure: public OopClosure {
2814 private:
2815   G1CollectedHeap* _g1h;
2816   VerifyOption     _vo;
2817   bool             _failures;
2818 public:
2819   // _vo == UsePrevMarking -> use "prev" marking information,
2820   // _vo == UseNextMarking -> use "next" marking information,
2821   // _vo == UseMarkWord    -> use mark word from object header.
2822   VerifyRootsClosure(VerifyOption vo) :
2823     _g1h(G1CollectedHeap::heap()),
2824     _vo(vo),
2825     _failures(false) { }
2826 
2827   bool failures() { return _failures; }
2828 
2829   template <class T> void do_oop_nv(T* p) {
2830     T heap_oop = oopDesc::load_heap_oop(p);
2831     if (!oopDesc::is_null(heap_oop)) {
2832       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2833       if (_g1h->is_obj_dead_cond(obj, _vo)) {
2834         gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2835                                "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2836         if (_vo == VerifyOption_G1UseMarkWord) {
2837           gclog_or_tty->print_cr("  Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2838         }
2839         obj->print_on(gclog_or_tty);
2840         _failures = true;
2841       }
2842     }
2843   }
2844 
2845   void do_oop(oop* p)       { do_oop_nv(p); }
2846   void do_oop(narrowOop* p) { do_oop_nv(p); }
2847 };
2848 
2849 class G1VerifyCodeRootOopClosure: public OopClosure {
2850   G1CollectedHeap* _g1h;
2851   OopClosure* _root_cl;
2852   nmethod* _nm;
2853   VerifyOption _vo;
2854   bool _failures;
2855 
2856   template <class T> void do_oop_work(T* p) {
2857     // First verify that this root is live
2858     _root_cl->do_oop(p);
2859 
2860     if (!G1VerifyHeapRegionCodeRoots) {
2861       // We're not verifying the code roots attached to heap region.
2862       return;
2863     }
2864 
2865     // Don't check the code roots during marking verification in a full GC
2866     if (_vo == VerifyOption_G1UseMarkWord) {
2867       return;
2868     }
2869 
2870     // Now verify that the current nmethod (which contains p) is
2871     // in the code root list of the heap region containing the
2872     // object referenced by p.
2873 
2874     T heap_oop = oopDesc::load_heap_oop(p);
2875     if (!oopDesc::is_null(heap_oop)) {
2876       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2877 
2878       // Now fetch the region containing the object
2879       HeapRegion* hr = _g1h->heap_region_containing(obj);
2880       HeapRegionRemSet* hrrs = hr->rem_set();
2881       // Verify that the strong code root list for this region
2882       // contains the nmethod
2883       if (!hrrs->strong_code_roots_list_contains(_nm)) {
2884         gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2885                                "from nmethod " PTR_FORMAT " not in strong "
2886                                "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2887                                p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2888         _failures = true;
2889       }
2890     }
2891   }
2892 
2893 public:
2894   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2895     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2896 
2897   void do_oop(oop* p) { do_oop_work(p); }
2898   void do_oop(narrowOop* p) { do_oop_work(p); }
2899 
2900   void set_nmethod(nmethod* nm) { _nm = nm; }
2901   bool failures() { return _failures; }
2902 };
2903 
2904 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2905   G1VerifyCodeRootOopClosure* _oop_cl;
2906 
2907 public:
2908   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2909     _oop_cl(oop_cl) {}
2910 
2911   void do_code_blob(CodeBlob* cb) {
2912     nmethod* nm = cb->as_nmethod_or_null();
2913     if (nm != NULL) {
2914       _oop_cl->set_nmethod(nm);
2915       nm->oops_do(_oop_cl);
2916     }
2917   }
2918 };
2919 
2920 class YoungRefCounterClosure : public OopClosure {
2921   G1CollectedHeap* _g1h;
2922   int              _count;
2923  public:
2924   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2925   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
2926   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2927 
2928   int count() { return _count; }
2929   void reset_count() { _count = 0; };
2930 };
2931 
2932 class VerifyKlassClosure: public KlassClosure {
2933   YoungRefCounterClosure _young_ref_counter_closure;
2934   OopClosure *_oop_closure;
2935  public:
2936   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2937   void do_klass(Klass* k) {
2938     k->oops_do(_oop_closure);
2939 
2940     _young_ref_counter_closure.reset_count();
2941     k->oops_do(&_young_ref_counter_closure);
2942     if (_young_ref_counter_closure.count() > 0) {
2943       guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2944     }
2945   }
2946 };
2947 
2948 class VerifyLivenessOopClosure: public OopClosure {
2949   G1CollectedHeap* _g1h;
2950   VerifyOption _vo;
2951 public:
2952   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2953     _g1h(g1h), _vo(vo)
2954   { }
2955   void do_oop(narrowOop *p) { do_oop_work(p); }
2956   void do_oop(      oop *p) { do_oop_work(p); }
2957 
2958   template <class T> void do_oop_work(T *p) {
2959     oop obj = oopDesc::load_decode_heap_oop(p);
2960     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2961               "Dead object referenced by a not dead object");
2962   }
2963 };
2964 
2965 class VerifyObjsInRegionClosure: public ObjectClosure {
2966 private:
2967   G1CollectedHeap* _g1h;
2968   size_t _live_bytes;
2969   HeapRegion *_hr;
2970   VerifyOption _vo;
2971 public:
2972   // _vo == UsePrevMarking -> use "prev" marking information,
2973   // _vo == UseNextMarking -> use "next" marking information,
2974   // _vo == UseMarkWord    -> use mark word from object header.
2975   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2976     : _live_bytes(0), _hr(hr), _vo(vo) {
2977     _g1h = G1CollectedHeap::heap();
2978   }
2979   void do_object(oop o) {
2980     VerifyLivenessOopClosure isLive(_g1h, _vo);
2981     assert(o != NULL, "Huh?");
2982     if (!_g1h->is_obj_dead_cond(o, _vo)) {
2983       // If the object is alive according to the mark word,
2984       // then verify that the marking information agrees.
2985       // Note we can't verify the contra-positive of the
2986       // above: if the object is dead (according to the mark
2987       // word), it may not be marked, or may have been marked
2988       // but has since became dead, or may have been allocated
2989       // since the last marking.
2990       if (_vo == VerifyOption_G1UseMarkWord) {
2991         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2992       }
2993 
2994       o->oop_iterate_no_header(&isLive);
2995       if (!_hr->obj_allocated_since_prev_marking(o)) {
2996         size_t obj_size = o->size();    // Make sure we don't overflow
2997         _live_bytes += (obj_size * HeapWordSize);
2998       }
2999     }
3000   }
3001   size_t live_bytes() { return _live_bytes; }
3002 };
3003 
3004 class VerifyArchiveOopClosure: public OopClosure {
3005 public:
3006   VerifyArchiveOopClosure(HeapRegion *hr) { }
3007   void do_oop(narrowOop *p) { do_oop_work(p); }
3008   void do_oop(      oop *p) { do_oop_work(p); }
3009 
3010   template <class T> void do_oop_work(T *p) {
3011     oop obj = oopDesc::load_decode_heap_oop(p);
3012     guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3013               "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3014               p2i(p), p2i(obj));
3015   }
3016 };
3017 
3018 class VerifyArchiveRegionClosure: public ObjectClosure {
3019 public:
3020   VerifyArchiveRegionClosure(HeapRegion *hr) { }
3021   // Verify that all object pointers are to archive regions.
3022   void do_object(oop o) {
3023     VerifyArchiveOopClosure checkOop(NULL);
3024     assert(o != NULL, "Should not be here for NULL oops");
3025     o->oop_iterate_no_header(&checkOop);
3026   }
3027 };
3028 
3029 class VerifyRegionClosure: public HeapRegionClosure {
3030 private:
3031   bool             _par;
3032   VerifyOption     _vo;
3033   bool             _failures;
3034 public:
3035   // _vo == UsePrevMarking -> use "prev" marking information,
3036   // _vo == UseNextMarking -> use "next" marking information,
3037   // _vo == UseMarkWord    -> use mark word from object header.
3038   VerifyRegionClosure(bool par, VerifyOption vo)
3039     : _par(par),
3040       _vo(vo),
3041       _failures(false) {}
3042 
3043   bool failures() {
3044     return _failures;
3045   }
3046 
3047   bool doHeapRegion(HeapRegion* r) {
3048     // For archive regions, verify there are no heap pointers to
3049     // non-pinned regions. For all others, verify liveness info.
3050     if (r->is_archive()) {
3051       VerifyArchiveRegionClosure verify_oop_pointers(r);
3052       r->object_iterate(&verify_oop_pointers);
3053       return true;
3054     }
3055     if (!r->is_continues_humongous()) {
3056       bool failures = false;
3057       r->verify(_vo, &failures);
3058       if (failures) {
3059         _failures = true;
3060       } else {
3061         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3062         r->object_iterate(&not_dead_yet_cl);
3063         if (_vo != VerifyOption_G1UseNextMarking) {
3064           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3065             gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3066                                    "max_live_bytes " SIZE_FORMAT " "
3067                                    "< calculated " SIZE_FORMAT,
3068                                    p2i(r->bottom()), p2i(r->end()),
3069                                    r->max_live_bytes(),
3070                                  not_dead_yet_cl.live_bytes());
3071             _failures = true;
3072           }
3073         } else {
3074           // When vo == UseNextMarking we cannot currently do a sanity
3075           // check on the live bytes as the calculation has not been
3076           // finalized yet.
3077         }
3078       }
3079     }
3080     return false; // stop the region iteration if we hit a failure
3081   }
3082 };
3083 
3084 // This is the task used for parallel verification of the heap regions
3085 
3086 class G1ParVerifyTask: public AbstractGangTask {
3087 private:
3088   G1CollectedHeap*  _g1h;
3089   VerifyOption      _vo;
3090   bool              _failures;
3091   HeapRegionClaimer _hrclaimer;
3092 
3093 public:
3094   // _vo == UsePrevMarking -> use "prev" marking information,
3095   // _vo == UseNextMarking -> use "next" marking information,
3096   // _vo == UseMarkWord    -> use mark word from object header.
3097   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3098       AbstractGangTask("Parallel verify task"),
3099       _g1h(g1h),
3100       _vo(vo),
3101       _failures(false),
3102       _hrclaimer(g1h->workers()->active_workers()) {}
3103 
3104   bool failures() {
3105     return _failures;
3106   }
3107 
3108   void work(uint worker_id) {
3109     HandleMark hm;
3110     VerifyRegionClosure blk(true, _vo);
3111     _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3112     if (blk.failures()) {
3113       _failures = true;
3114     }
3115   }
3116 };
3117 
3118 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3119   if (SafepointSynchronize::is_at_safepoint()) {
3120     assert(Thread::current()->is_VM_thread(),
3121            "Expected to be executed serially by the VM thread at this point");
3122 
3123     if (!silent) { gclog_or_tty->print("Roots "); }
3124     VerifyRootsClosure rootsCl(vo);
3125     VerifyKlassClosure klassCl(this, &rootsCl);
3126     CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3127 
3128     // We apply the relevant closures to all the oops in the
3129     // system dictionary, class loader data graph, the string table
3130     // and the nmethods in the code cache.
3131     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3132     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3133 
3134     {
3135       G1RootProcessor root_processor(this, 1);
3136       root_processor.process_all_roots(&rootsCl,
3137                                        &cldCl,
3138                                        &blobsCl);
3139     }
3140 
3141     bool failures = rootsCl.failures() || codeRootsCl.failures();
3142 
3143     if (vo != VerifyOption_G1UseMarkWord) {
3144       // If we're verifying during a full GC then the region sets
3145       // will have been torn down at the start of the GC. Therefore
3146       // verifying the region sets will fail. So we only verify
3147       // the region sets when not in a full GC.
3148       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3149       verify_region_sets();
3150     }
3151 
3152     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3153     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3154 
3155       G1ParVerifyTask task(this, vo);
3156       workers()->run_task(&task);
3157       if (task.failures()) {
3158         failures = true;
3159       }
3160 
3161     } else {
3162       VerifyRegionClosure blk(false, vo);
3163       heap_region_iterate(&blk);
3164       if (blk.failures()) {
3165         failures = true;
3166       }
3167     }
3168 
3169     if (G1StringDedup::is_enabled()) {
3170       if (!silent) gclog_or_tty->print("StrDedup ");
3171       G1StringDedup::verify();
3172     }
3173 
3174     if (failures) {
3175       gclog_or_tty->print_cr("Heap:");
3176       // It helps to have the per-region information in the output to
3177       // help us track down what went wrong. This is why we call
3178       // print_extended_on() instead of print_on().
3179       print_extended_on(gclog_or_tty);
3180       gclog_or_tty->cr();
3181       gclog_or_tty->flush();
3182     }
3183     guarantee(!failures, "there should not have been any failures");
3184   } else {
3185     if (!silent) {
3186       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3187       if (G1StringDedup::is_enabled()) {
3188         gclog_or_tty->print(", StrDedup");
3189       }
3190       gclog_or_tty->print(") ");
3191     }
3192   }
3193 }
3194 
3195 void G1CollectedHeap::verify(bool silent) {
3196   verify(silent, VerifyOption_G1UsePrevMarking);
3197 }
3198 
3199 double G1CollectedHeap::verify(bool guard, const char* msg) {
3200   double verify_time_ms = 0.0;
3201 
3202   if (guard && total_collections() >= VerifyGCStartAt) {
3203     double verify_start = os::elapsedTime();
3204     HandleMark hm;  // Discard invalid handles created during verification
3205     prepare_for_verify();
3206     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3207     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3208   }
3209 
3210   return verify_time_ms;
3211 }
3212 
3213 void G1CollectedHeap::verify_before_gc() {
3214   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3215   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3216 }
3217 
3218 void G1CollectedHeap::verify_after_gc() {
3219   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3220   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3221 }
3222 
3223 class PrintRegionClosure: public HeapRegionClosure {
3224   outputStream* _st;
3225 public:
3226   PrintRegionClosure(outputStream* st) : _st(st) {}
3227   bool doHeapRegion(HeapRegion* r) {
3228     r->print_on(_st);
3229     return false;
3230   }
3231 };
3232 
3233 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3234                                        const HeapRegion* hr,
3235                                        const VerifyOption vo) const {
3236   switch (vo) {
3237   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3238   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3239   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
3240   default:                            ShouldNotReachHere();
3241   }
3242   return false; // keep some compilers happy
3243 }
3244 
3245 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3246                                        const VerifyOption vo) const {
3247   switch (vo) {
3248   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3249   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3250   case VerifyOption_G1UseMarkWord: {
3251     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3252     return !obj->is_gc_marked() && !hr->is_archive();
3253   }
3254   default:                            ShouldNotReachHere();
3255   }
3256   return false; // keep some compilers happy
3257 }
3258 
3259 void G1CollectedHeap::print_on(outputStream* st) const {
3260   st->print(" %-20s", "garbage-first heap");
3261   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3262             capacity()/K, used_unlocked()/K);
3263   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3264             p2i(_hrm.reserved().start()),
3265             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3266             p2i(_hrm.reserved().end()));
3267   st->cr();
3268   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3269   uint young_regions = _young_list->length();
3270   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3271             (size_t) young_regions * HeapRegion::GrainBytes / K);
3272   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3273   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3274             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3275   st->cr();
3276   MetaspaceAux::print_on(st);
3277 }
3278 
3279 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3280   print_on(st);
3281 
3282   // Print the per-region information.
3283   st->cr();
3284   st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3285                "HS=humongous(starts), HC=humongous(continues), "
3286                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3287                "PTAMS=previous top-at-mark-start, "
3288                "NTAMS=next top-at-mark-start)");
3289   PrintRegionClosure blk(st);
3290   heap_region_iterate(&blk);
3291 }
3292 
3293 void G1CollectedHeap::print_on_error(outputStream* st) const {
3294   this->CollectedHeap::print_on_error(st);
3295 
3296   if (_cm != NULL) {
3297     st->cr();
3298     _cm->print_on_error(st);
3299   }
3300 }
3301 
3302 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3303   workers()->print_worker_threads_on(st);
3304   _cmThread->print_on(st);
3305   st->cr();
3306   _cm->print_worker_threads_on(st);
3307   _cg1r->print_worker_threads_on(st);
3308   if (G1StringDedup::is_enabled()) {
3309     G1StringDedup::print_worker_threads_on(st);
3310   }
3311 }
3312 
3313 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3314   workers()->threads_do(tc);
3315   tc->do_thread(_cmThread);
3316   _cg1r->threads_do(tc);
3317   if (G1StringDedup::is_enabled()) {
3318     G1StringDedup::threads_do(tc);
3319   }
3320 }
3321 
3322 void G1CollectedHeap::print_tracing_info() const {
3323   // We'll overload this to mean "trace GC pause statistics."
3324   if (TraceYoungGenTime || TraceOldGenTime) {
3325     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3326     // to that.
3327     g1_policy()->print_tracing_info();
3328   }
3329   if (G1SummarizeRSetStats) {
3330     g1_rem_set()->print_summary_info();
3331   }
3332   if (G1SummarizeConcMark) {
3333     concurrent_mark()->print_summary_info();
3334   }
3335   g1_policy()->print_yg_surv_rate_info();
3336 }
3337 
3338 #ifndef PRODUCT
3339 // Helpful for debugging RSet issues.
3340 
3341 class PrintRSetsClosure : public HeapRegionClosure {
3342 private:
3343   const char* _msg;
3344   size_t _occupied_sum;
3345 
3346 public:
3347   bool doHeapRegion(HeapRegion* r) {
3348     HeapRegionRemSet* hrrs = r->rem_set();
3349     size_t occupied = hrrs->occupied();
3350     _occupied_sum += occupied;
3351 
3352     gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3353                            HR_FORMAT_PARAMS(r));
3354     if (occupied == 0) {
3355       gclog_or_tty->print_cr("  RSet is empty");
3356     } else {
3357       hrrs->print();
3358     }
3359     gclog_or_tty->print_cr("----------");
3360     return false;
3361   }
3362 
3363   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3364     gclog_or_tty->cr();
3365     gclog_or_tty->print_cr("========================================");
3366     gclog_or_tty->print_cr("%s", msg);
3367     gclog_or_tty->cr();
3368   }
3369 
3370   ~PrintRSetsClosure() {
3371     gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3372     gclog_or_tty->print_cr("========================================");
3373     gclog_or_tty->cr();
3374   }
3375 };
3376 
3377 void G1CollectedHeap::print_cset_rsets() {
3378   PrintRSetsClosure cl("Printing CSet RSets");
3379   collection_set_iterate(&cl);
3380 }
3381 
3382 void G1CollectedHeap::print_all_rsets() {
3383   PrintRSetsClosure cl("Printing All RSets");;
3384   heap_region_iterate(&cl);
3385 }
3386 #endif // PRODUCT
3387 
3388 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3389   YoungList* young_list = heap()->young_list();
3390 
3391   size_t eden_used_bytes = young_list->eden_used_bytes();
3392   size_t survivor_used_bytes = young_list->survivor_used_bytes();
3393 
3394   size_t eden_capacity_bytes =
3395     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3396 
3397   VirtualSpaceSummary heap_summary = create_heap_space_summary();
3398   return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3399 }
3400 
3401 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3402   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3403                        stats->unused(), stats->used(), stats->region_end_waste(),
3404                        stats->regions_filled(), stats->direct_allocated(),
3405                        stats->failure_used(), stats->failure_waste());
3406 }
3407 
3408 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3409   const G1HeapSummary& heap_summary = create_g1_heap_summary();
3410   gc_tracer->report_gc_heap_summary(when, heap_summary);
3411 
3412   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3413   gc_tracer->report_metaspace_summary(when, metaspace_summary);
3414 }
3415 
3416 
3417 G1CollectedHeap* G1CollectedHeap::heap() {
3418   CollectedHeap* heap = Universe::heap();
3419   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3420   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3421   return (G1CollectedHeap*)heap;
3422 }
3423 
3424 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3425   // always_do_update_barrier = false;
3426   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3427   // Fill TLAB's and such
3428   accumulate_statistics_all_tlabs();
3429   ensure_parsability(true);
3430 
3431   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3432       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3433     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3434   }
3435 }
3436 
3437 void G1CollectedHeap::gc_epilogue(bool full) {
3438 
3439   if (G1SummarizeRSetStats &&
3440       (G1SummarizeRSetStatsPeriod > 0) &&
3441       // we are at the end of the GC. Total collections has already been increased.
3442       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3443     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3444   }
3445 
3446   // FIXME: what is this about?
3447   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3448   // is set.
3449 #if defined(COMPILER2) || INCLUDE_JVMCI
3450   assert(DerivedPointerTable::is_empty(), "derived pointer present");
3451 #endif
3452   // always_do_update_barrier = true;
3453 
3454   resize_all_tlabs();
3455   allocation_context_stats().update(full);
3456 
3457   // We have just completed a GC. Update the soft reference
3458   // policy with the new heap occupancy
3459   Universe::update_heap_info_at_gc();
3460 }
3461 
3462 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3463                                                uint gc_count_before,
3464                                                bool* succeeded,
3465                                                GCCause::Cause gc_cause) {
3466   assert_heap_not_locked_and_not_at_safepoint();
3467   g1_policy()->record_stop_world_start();
3468   VM_G1IncCollectionPause op(gc_count_before,
3469                              word_size,
3470                              false, /* should_initiate_conc_mark */
3471                              g1_policy()->max_pause_time_ms(),
3472                              gc_cause);
3473 
3474   op.set_allocation_context(AllocationContext::current());
3475   VMThread::execute(&op);
3476 
3477   HeapWord* result = op.result();
3478   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3479   assert(result == NULL || ret_succeeded,
3480          "the result should be NULL if the VM did not succeed");
3481   *succeeded = ret_succeeded;
3482 
3483   assert_heap_not_locked();
3484   return result;
3485 }
3486 
3487 void
3488 G1CollectedHeap::doConcurrentMark() {
3489   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3490   if (!_cmThread->in_progress()) {
3491     _cmThread->set_started();
3492     CGC_lock->notify();
3493   }
3494 }
3495 
3496 size_t G1CollectedHeap::pending_card_num() {
3497   size_t extra_cards = 0;
3498   JavaThread *curr = Threads::first();
3499   while (curr != NULL) {
3500     DirtyCardQueue& dcq = curr->dirty_card_queue();
3501     extra_cards += dcq.size();
3502     curr = curr->next();
3503   }
3504   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3505   size_t buffer_size = dcqs.buffer_size();
3506   size_t buffer_num = dcqs.completed_buffers_num();
3507 
3508   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3509   // in bytes - not the number of 'entries'. We need to convert
3510   // into a number of cards.
3511   return (buffer_size * buffer_num + extra_cards) / oopSize;
3512 }
3513 
3514 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3515  private:
3516   size_t _total_humongous;
3517   size_t _candidate_humongous;
3518 
3519   DirtyCardQueue _dcq;
3520 
3521   // We don't nominate objects with many remembered set entries, on
3522   // the assumption that such objects are likely still live.
3523   bool is_remset_small(HeapRegion* region) const {
3524     HeapRegionRemSet* const rset = region->rem_set();
3525     return G1EagerReclaimHumongousObjectsWithStaleRefs
3526       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3527       : rset->is_empty();
3528   }
3529 
3530   bool is_typeArray_region(HeapRegion* region) const {
3531     return oop(region->bottom())->is_typeArray();
3532   }
3533 
3534   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3535     assert(region->is_starts_humongous(), "Must start a humongous object");
3536 
3537     // Candidate selection must satisfy the following constraints
3538     // while concurrent marking is in progress:
3539     //
3540     // * In order to maintain SATB invariants, an object must not be
3541     // reclaimed if it was allocated before the start of marking and
3542     // has not had its references scanned.  Such an object must have
3543     // its references (including type metadata) scanned to ensure no
3544     // live objects are missed by the marking process.  Objects
3545     // allocated after the start of concurrent marking don't need to
3546     // be scanned.
3547     //
3548     // * An object must not be reclaimed if it is on the concurrent
3549     // mark stack.  Objects allocated after the start of concurrent
3550     // marking are never pushed on the mark stack.
3551     //
3552     // Nominating only objects allocated after the start of concurrent
3553     // marking is sufficient to meet both constraints.  This may miss
3554     // some objects that satisfy the constraints, but the marking data
3555     // structures don't support efficiently performing the needed
3556     // additional tests or scrubbing of the mark stack.
3557     //
3558     // However, we presently only nominate is_typeArray() objects.
3559     // A humongous object containing references induces remembered
3560     // set entries on other regions.  In order to reclaim such an
3561     // object, those remembered sets would need to be cleaned up.
3562     //
3563     // We also treat is_typeArray() objects specially, allowing them
3564     // to be reclaimed even if allocated before the start of
3565     // concurrent mark.  For this we rely on mark stack insertion to
3566     // exclude is_typeArray() objects, preventing reclaiming an object
3567     // that is in the mark stack.  We also rely on the metadata for
3568     // such objects to be built-in and so ensured to be kept live.
3569     // Frequent allocation and drop of large binary blobs is an
3570     // important use case for eager reclaim, and this special handling
3571     // may reduce needed headroom.
3572 
3573     return is_typeArray_region(region) && is_remset_small(region);
3574   }
3575 
3576  public:
3577   RegisterHumongousWithInCSetFastTestClosure()
3578   : _total_humongous(0),
3579     _candidate_humongous(0),
3580     _dcq(&JavaThread::dirty_card_queue_set()) {
3581   }
3582 
3583   virtual bool doHeapRegion(HeapRegion* r) {
3584     if (!r->is_starts_humongous()) {
3585       return false;
3586     }
3587     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3588 
3589     bool is_candidate = humongous_region_is_candidate(g1h, r);
3590     uint rindex = r->hrm_index();
3591     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3592     if (is_candidate) {
3593       _candidate_humongous++;
3594       g1h->register_humongous_region_with_cset(rindex);
3595       // Is_candidate already filters out humongous object with large remembered sets.
3596       // If we have a humongous object with a few remembered sets, we simply flush these
3597       // remembered set entries into the DCQS. That will result in automatic
3598       // re-evaluation of their remembered set entries during the following evacuation
3599       // phase.
3600       if (!r->rem_set()->is_empty()) {
3601         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3602                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3603         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3604         HeapRegionRemSetIterator hrrs(r->rem_set());
3605         size_t card_index;
3606         while (hrrs.has_next(card_index)) {
3607           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3608           // The remembered set might contain references to already freed
3609           // regions. Filter out such entries to avoid failing card table
3610           // verification.
3611           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3612             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3613               *card_ptr = CardTableModRefBS::dirty_card_val();
3614               _dcq.enqueue(card_ptr);
3615             }
3616           }
3617         }
3618         r->rem_set()->clear_locked();
3619       }
3620       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3621     }
3622     _total_humongous++;
3623 
3624     return false;
3625   }
3626 
3627   size_t total_humongous() const { return _total_humongous; }
3628   size_t candidate_humongous() const { return _candidate_humongous; }
3629 
3630   void flush_rem_set_entries() { _dcq.flush(); }
3631 };
3632 
3633 void G1CollectedHeap::register_humongous_regions_with_cset() {
3634   if (!G1EagerReclaimHumongousObjects) {
3635     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3636     return;
3637   }
3638   double time = os::elapsed_counter();
3639 
3640   // Collect reclaim candidate information and register candidates with cset.
3641   RegisterHumongousWithInCSetFastTestClosure cl;
3642   heap_region_iterate(&cl);
3643 
3644   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3645   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3646                                                                   cl.total_humongous(),
3647                                                                   cl.candidate_humongous());
3648   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3649 
3650   // Finally flush all remembered set entries to re-check into the global DCQS.
3651   cl.flush_rem_set_entries();
3652 }
3653 
3654 #ifdef ASSERT
3655 class VerifyCSetClosure: public HeapRegionClosure {
3656 public:
3657   bool doHeapRegion(HeapRegion* hr) {
3658     // Here we check that the CSet region's RSet is ready for parallel
3659     // iteration. The fields that we'll verify are only manipulated
3660     // when the region is part of a CSet and is collected. Afterwards,
3661     // we reset these fields when we clear the region's RSet (when the
3662     // region is freed) so they are ready when the region is
3663     // re-allocated. The only exception to this is if there's an
3664     // evacuation failure and instead of freeing the region we leave
3665     // it in the heap. In that case, we reset these fields during
3666     // evacuation failure handling.
3667     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3668 
3669     // Here's a good place to add any other checks we'd like to
3670     // perform on CSet regions.
3671     return false;
3672   }
3673 };
3674 #endif // ASSERT
3675 
3676 uint G1CollectedHeap::num_task_queues() const {
3677   return _task_queues->size();
3678 }
3679 
3680 #if TASKQUEUE_STATS
3681 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3682   st->print_raw_cr("GC Task Stats");
3683   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3684   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3685 }
3686 
3687 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3688   print_taskqueue_stats_hdr(st);
3689 
3690   TaskQueueStats totals;
3691   const uint n = num_task_queues();
3692   for (uint i = 0; i < n; ++i) {
3693     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3694     totals += task_queue(i)->stats;
3695   }
3696   st->print_raw("tot "); totals.print(st); st->cr();
3697 
3698   DEBUG_ONLY(totals.verify());
3699 }
3700 
3701 void G1CollectedHeap::reset_taskqueue_stats() {
3702   const uint n = num_task_queues();
3703   for (uint i = 0; i < n; ++i) {
3704     task_queue(i)->stats.reset();
3705   }
3706 }
3707 #endif // TASKQUEUE_STATS
3708 
3709 void G1CollectedHeap::log_gc_header() {
3710   if (!G1Log::fine()) {
3711     return;
3712   }
3713 
3714   gclog_or_tty->gclog_stamp();
3715 
3716   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3717     .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3718     .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3719 
3720   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3721 }
3722 
3723 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3724   if (!G1Log::fine()) {
3725     return;
3726   }
3727 
3728   if (G1Log::finer()) {
3729     if (evacuation_failed()) {
3730       gclog_or_tty->print(" (to-space exhausted)");
3731     }
3732     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3733     g1_policy()->print_phases(pause_time_sec);
3734     g1_policy()->print_detailed_heap_transition();
3735   } else {
3736     if (evacuation_failed()) {
3737       gclog_or_tty->print("--");
3738     }
3739     g1_policy()->print_heap_transition();
3740     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3741   }
3742   gclog_or_tty->flush();
3743 }
3744 
3745 void G1CollectedHeap::wait_for_root_region_scanning() {
3746   double scan_wait_start = os::elapsedTime();
3747   // We have to wait until the CM threads finish scanning the
3748   // root regions as it's the only way to ensure that all the
3749   // objects on them have been correctly scanned before we start
3750   // moving them during the GC.
3751   bool waited = _cm->root_regions()->wait_until_scan_finished();
3752   double wait_time_ms = 0.0;
3753   if (waited) {
3754     double scan_wait_end = os::elapsedTime();
3755     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3756   }
3757   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3758 }
3759 
3760 bool
3761 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3762   assert_at_safepoint(true /* should_be_vm_thread */);
3763   guarantee(!is_gc_active(), "collection is not reentrant");
3764 
3765   if (GC_locker::check_active_before_gc()) {
3766     return false;
3767   }
3768 
3769   _gc_timer_stw->register_gc_start();
3770 
3771   GCIdMark gc_id_mark;
3772   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3773 
3774   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3775   ResourceMark rm;
3776 
3777   wait_for_root_region_scanning();
3778 
3779   G1Log::update_level();
3780   print_heap_before_gc();
3781   trace_heap_before_gc(_gc_tracer_stw);
3782 
3783   verify_region_sets_optional();
3784   verify_dirty_young_regions();
3785 
3786   // This call will decide whether this pause is an initial-mark
3787   // pause. If it is, during_initial_mark_pause() will return true
3788   // for the duration of this pause.
3789   g1_policy()->decide_on_conc_mark_initiation();
3790 
3791   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3792   assert(!collector_state()->during_initial_mark_pause() ||
3793           collector_state()->gcs_are_young(), "sanity");
3794 
3795   // We also do not allow mixed GCs during marking.
3796   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3797 
3798   // Record whether this pause is an initial mark. When the current
3799   // thread has completed its logging output and it's safe to signal
3800   // the CM thread, the flag's value in the policy has been reset.
3801   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3802 
3803   // Inner scope for scope based logging, timers, and stats collection
3804   {
3805     EvacuationInfo evacuation_info;
3806 
3807     if (collector_state()->during_initial_mark_pause()) {
3808       // We are about to start a marking cycle, so we increment the
3809       // full collection counter.
3810       increment_old_marking_cycles_started();
3811       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3812     }
3813 
3814     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3815 
3816     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3817 
3818     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3819                                                                   workers()->active_workers(),
3820                                                                   Threads::number_of_non_daemon_threads());
3821     workers()->set_active_workers(active_workers);
3822 
3823     double pause_start_sec = os::elapsedTime();
3824     g1_policy()->note_gc_start(active_workers);
3825     log_gc_header();
3826 
3827     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3828     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3829 
3830     // If the secondary_free_list is not empty, append it to the
3831     // free_list. No need to wait for the cleanup operation to finish;
3832     // the region allocation code will check the secondary_free_list
3833     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3834     // set, skip this step so that the region allocation code has to
3835     // get entries from the secondary_free_list.
3836     if (!G1StressConcRegionFreeing) {
3837       append_secondary_free_list_if_not_empty_with_lock();
3838     }
3839 
3840     assert(check_young_list_well_formed(), "young list should be well formed");
3841 
3842     // Don't dynamically change the number of GC threads this early.  A value of
3843     // 0 is used to indicate serial work.  When parallel work is done,
3844     // it will be set.
3845 
3846     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3847       IsGCActiveMark x;
3848 
3849       gc_prologue(false);
3850       increment_total_collections(false /* full gc */);
3851       increment_gc_time_stamp();
3852 
3853       verify_before_gc();
3854 
3855       check_bitmaps("GC Start");
3856 
3857 #if defined(COMPILER2) || INCLUDE_JVMCI
3858       DerivedPointerTable::clear();
3859 #endif
3860 
3861       // Please see comment in g1CollectedHeap.hpp and
3862       // G1CollectedHeap::ref_processing_init() to see how
3863       // reference processing currently works in G1.
3864 
3865       // Enable discovery in the STW reference processor
3866       ref_processor_stw()->enable_discovery();
3867 
3868       {
3869         // We want to temporarily turn off discovery by the
3870         // CM ref processor, if necessary, and turn it back on
3871         // on again later if we do. Using a scoped
3872         // NoRefDiscovery object will do this.
3873         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3874 
3875         // Forget the current alloc region (we might even choose it to be part
3876         // of the collection set!).
3877         _allocator->release_mutator_alloc_region();
3878 
3879         // We should call this after we retire the mutator alloc
3880         // region(s) so that all the ALLOC / RETIRE events are generated
3881         // before the start GC event.
3882         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3883 
3884         // This timing is only used by the ergonomics to handle our pause target.
3885         // It is unclear why this should not include the full pause. We will
3886         // investigate this in CR 7178365.
3887         //
3888         // Preserving the old comment here if that helps the investigation:
3889         //
3890         // The elapsed time induced by the start time below deliberately elides
3891         // the possible verification above.
3892         double sample_start_time_sec = os::elapsedTime();
3893 
3894         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3895 
3896         if (collector_state()->during_initial_mark_pause()) {
3897           concurrent_mark()->checkpointRootsInitialPre();
3898         }
3899 
3900         double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3901         g1_policy()->finalize_old_cset_part(time_remaining_ms);
3902 
3903         evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3904 
3905         register_humongous_regions_with_cset();
3906 
3907         assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3908 
3909         _cm->note_start_of_gc();
3910         // We call this after finalize_cset() to
3911         // ensure that the CSet has been finalized.
3912         _cm->verify_no_cset_oops();
3913 
3914         if (_hr_printer.is_active()) {
3915           HeapRegion* hr = g1_policy()->collection_set();
3916           while (hr != NULL) {
3917             _hr_printer.cset(hr);
3918             hr = hr->next_in_collection_set();
3919           }
3920         }
3921 
3922 #ifdef ASSERT
3923         VerifyCSetClosure cl;
3924         collection_set_iterate(&cl);
3925 #endif // ASSERT
3926 
3927         // Initialize the GC alloc regions.
3928         _allocator->init_gc_alloc_regions(evacuation_info);
3929 
3930         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3931         pre_evacuate_collection_set();
3932 
3933         // Actually do the work...
3934         evacuate_collection_set(evacuation_info, &per_thread_states);
3935 
3936         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3937 
3938         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3939         free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3940 
3941         eagerly_reclaim_humongous_regions();
3942 
3943         g1_policy()->clear_collection_set();
3944 
3945         // Start a new incremental collection set for the next pause.
3946         g1_policy()->start_incremental_cset_building();
3947 
3948         clear_cset_fast_test();
3949 
3950         _young_list->reset_sampled_info();
3951 
3952         // Don't check the whole heap at this point as the
3953         // GC alloc regions from this pause have been tagged
3954         // as survivors and moved on to the survivor list.
3955         // Survivor regions will fail the !is_young() check.
3956         assert(check_young_list_empty(false /* check_heap */),
3957           "young list should be empty");
3958 
3959         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3960                                              _young_list->first_survivor_region(),
3961                                              _young_list->last_survivor_region());
3962 
3963         _young_list->reset_auxilary_lists();
3964 
3965         if (evacuation_failed()) {
3966           set_used(recalculate_used());
3967           if (_archive_allocator != NULL) {
3968             _archive_allocator->clear_used();
3969           }
3970           for (uint i = 0; i < ParallelGCThreads; i++) {
3971             if (_evacuation_failed_info_array[i].has_failed()) {
3972               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3973             }
3974           }
3975         } else {
3976           // The "used" of the the collection set have already been subtracted
3977           // when they were freed.  Add in the bytes evacuated.
3978           increase_used(g1_policy()->bytes_copied_during_gc());
3979         }
3980 
3981         if (collector_state()->during_initial_mark_pause()) {
3982           // We have to do this before we notify the CM threads that
3983           // they can start working to make sure that all the
3984           // appropriate initialization is done on the CM object.
3985           concurrent_mark()->checkpointRootsInitialPost();
3986           collector_state()->set_mark_in_progress(true);
3987           // Note that we don't actually trigger the CM thread at
3988           // this point. We do that later when we're sure that
3989           // the current thread has completed its logging output.
3990         }
3991 
3992         allocate_dummy_regions();
3993 
3994         _allocator->init_mutator_alloc_region();
3995 
3996         {
3997           size_t expand_bytes = g1_policy()->expansion_amount();
3998           if (expand_bytes > 0) {
3999             size_t bytes_before = capacity();
4000             // No need for an ergo verbose message here,
4001             // expansion_amount() does this when it returns a value > 0.
4002             double expand_ms;
4003             if (!expand(expand_bytes, &expand_ms)) {
4004               // We failed to expand the heap. Cannot do anything about it.
4005             }
4006             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
4007           }
4008         }
4009 
4010         // We redo the verification but now wrt to the new CSet which
4011         // has just got initialized after the previous CSet was freed.
4012         _cm->verify_no_cset_oops();
4013         _cm->note_end_of_gc();
4014 
4015         // This timing is only used by the ergonomics to handle our pause target.
4016         // It is unclear why this should not include the full pause. We will
4017         // investigate this in CR 7178365.
4018         double sample_end_time_sec = os::elapsedTime();
4019         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4020         size_t total_cards_scanned = per_thread_states.total_cards_scanned();
4021         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
4022 
4023         evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
4024         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
4025 
4026         MemoryService::track_memory_usage();
4027 
4028         // In prepare_for_verify() below we'll need to scan the deferred
4029         // update buffers to bring the RSets up-to-date if
4030         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4031         // the update buffers we'll probably need to scan cards on the
4032         // regions we just allocated to (i.e., the GC alloc
4033         // regions). However, during the last GC we called
4034         // set_saved_mark() on all the GC alloc regions, so card
4035         // scanning might skip the [saved_mark_word()...top()] area of
4036         // those regions (i.e., the area we allocated objects into
4037         // during the last GC). But it shouldn't. Given that
4038         // saved_mark_word() is conditional on whether the GC time stamp
4039         // on the region is current or not, by incrementing the GC time
4040         // stamp here we invalidate all the GC time stamps on all the
4041         // regions and saved_mark_word() will simply return top() for
4042         // all the regions. This is a nicer way of ensuring this rather
4043         // than iterating over the regions and fixing them. In fact, the
4044         // GC time stamp increment here also ensures that
4045         // saved_mark_word() will return top() between pauses, i.e.,
4046         // during concurrent refinement. So we don't need the
4047         // is_gc_active() check to decided which top to use when
4048         // scanning cards (see CR 7039627).
4049         increment_gc_time_stamp();
4050 
4051         verify_after_gc();
4052         check_bitmaps("GC End");
4053 
4054         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4055         ref_processor_stw()->verify_no_references_recorded();
4056 
4057         // CM reference discovery will be re-enabled if necessary.
4058       }
4059 
4060       // We should do this after we potentially expand the heap so
4061       // that all the COMMIT events are generated before the end GC
4062       // event, and after we retire the GC alloc regions so that all
4063       // RETIRE events are generated before the end GC event.
4064       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4065 
4066 #ifdef TRACESPINNING
4067       ParallelTaskTerminator::print_termination_counts();
4068 #endif
4069 
4070       gc_epilogue(false);
4071     }
4072 
4073     // Print the remainder of the GC log output.
4074     log_gc_footer(os::elapsedTime() - pause_start_sec);
4075 
4076     // It is not yet to safe to tell the concurrent mark to
4077     // start as we have some optional output below. We don't want the
4078     // output from the concurrent mark thread interfering with this
4079     // logging output either.
4080 
4081     _hrm.verify_optional();
4082     verify_region_sets_optional();
4083 
4084     TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4085     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4086 
4087     print_heap_after_gc();
4088     trace_heap_after_gc(_gc_tracer_stw);
4089 
4090     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4091     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4092     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4093     // before any GC notifications are raised.
4094     g1mm()->update_sizes();
4095 
4096     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4097     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4098     _gc_timer_stw->register_gc_end();
4099     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4100   }
4101   // It should now be safe to tell the concurrent mark thread to start
4102   // without its logging output interfering with the logging output
4103   // that came from the pause.
4104 
4105   if (should_start_conc_mark) {
4106     // CAUTION: after the doConcurrentMark() call below,
4107     // the concurrent marking thread(s) could be running
4108     // concurrently with us. Make sure that anything after
4109     // this point does not assume that we are the only GC thread
4110     // running. Note: of course, the actual marking work will
4111     // not start until the safepoint itself is released in
4112     // SuspendibleThreadSet::desynchronize().
4113     doConcurrentMark();
4114   }
4115 
4116   return true;
4117 }
4118 
4119 void G1CollectedHeap::remove_self_forwarding_pointers() {
4120   double remove_self_forwards_start = os::elapsedTime();
4121 
4122   G1ParRemoveSelfForwardPtrsTask rsfp_task;
4123   workers()->run_task(&rsfp_task);
4124 
4125   // Now restore saved marks, if any.
4126   for (uint i = 0; i < ParallelGCThreads; i++) {
4127     OopAndMarkOopStack& cur = _preserved_objs[i];
4128     while (!cur.is_empty()) {
4129       OopAndMarkOop elem = cur.pop();
4130       elem.set_mark();
4131     }
4132     cur.clear(true);
4133   }
4134 
4135   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4136 }
4137 
4138 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4139   if (!_evacuation_failed) {
4140     _evacuation_failed = true;
4141   }
4142 
4143   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4144 
4145   // We want to call the "for_promotion_failure" version only in the
4146   // case of a promotion failure.
4147   if (m->must_be_preserved_for_promotion_failure(obj)) {
4148     OopAndMarkOop elem(obj, m);
4149     _preserved_objs[worker_id].push(elem);
4150   }
4151 }
4152 
4153 class G1ParEvacuateFollowersClosure : public VoidClosure {
4154 private:
4155   double _start_term;
4156   double _term_time;
4157   size_t _term_attempts;
4158 
4159   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4160   void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4161 protected:
4162   G1CollectedHeap*              _g1h;
4163   G1ParScanThreadState*         _par_scan_state;
4164   RefToScanQueueSet*            _queues;
4165   ParallelTaskTerminator*       _terminator;
4166 
4167   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4168   RefToScanQueueSet*      queues()         { return _queues; }
4169   ParallelTaskTerminator* terminator()     { return _terminator; }
4170 
4171 public:
4172   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4173                                 G1ParScanThreadState* par_scan_state,
4174                                 RefToScanQueueSet* queues,
4175                                 ParallelTaskTerminator* terminator)
4176     : _g1h(g1h), _par_scan_state(par_scan_state),
4177       _queues(queues), _terminator(terminator),
4178       _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4179 
4180   void do_void();
4181 
4182   double term_time() const { return _term_time; }
4183   size_t term_attempts() const { return _term_attempts; }
4184 
4185 private:
4186   inline bool offer_termination();
4187 };
4188 
4189 bool G1ParEvacuateFollowersClosure::offer_termination() {
4190   G1ParScanThreadState* const pss = par_scan_state();
4191   start_term_time();
4192   const bool res = terminator()->offer_termination();
4193   end_term_time();
4194   return res;
4195 }
4196 
4197 void G1ParEvacuateFollowersClosure::do_void() {
4198   G1ParScanThreadState* const pss = par_scan_state();
4199   pss->trim_queue();
4200   do {
4201     pss->steal_and_trim_queue(queues());
4202   } while (!offer_termination());
4203 }
4204 
4205 class G1ParTask : public AbstractGangTask {
4206 protected:
4207   G1CollectedHeap*         _g1h;
4208   G1ParScanThreadStateSet* _pss;
4209   RefToScanQueueSet*       _queues;
4210   G1RootProcessor*         _root_processor;
4211   ParallelTaskTerminator   _terminator;
4212   uint                     _n_workers;
4213 
4214 public:
4215   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4216     : AbstractGangTask("G1 collection"),
4217       _g1h(g1h),
4218       _pss(per_thread_states),
4219       _queues(task_queues),
4220       _root_processor(root_processor),
4221       _terminator(n_workers, _queues),
4222       _n_workers(n_workers)
4223   {}
4224 
4225   void work(uint worker_id) {
4226     if (worker_id >= _n_workers) return;  // no work needed this round
4227 
4228     double start_sec = os::elapsedTime();
4229     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4230 
4231     {
4232       ResourceMark rm;
4233       HandleMark   hm;
4234 
4235       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4236 
4237       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
4238       pss->set_ref_processor(rp);
4239 
4240       double start_strong_roots_sec = os::elapsedTime();
4241 
4242       _root_processor->evacuate_roots(pss->closures(), worker_id);
4243 
4244       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4245 
4246       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4247       // treating the nmethods visited to act as roots for concurrent marking.
4248       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4249       // objects copied by the current evacuation.
4250       size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4251                                                                              pss->closures()->weak_codeblobs(),
4252                                                                              worker_id);
4253 
4254       _pss->add_cards_scanned(worker_id, cards_scanned);
4255 
4256       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4257 
4258       double term_sec = 0.0;
4259       size_t evac_term_attempts = 0;
4260       {
4261         double start = os::elapsedTime();
4262         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4263         evac.do_void();
4264 
4265         evac_term_attempts = evac.term_attempts();
4266         term_sec = evac.term_time();
4267         double elapsed_sec = os::elapsedTime() - start;
4268         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4269         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4270         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4271       }
4272 
4273       assert(pss->queue_is_empty(), "should be empty");
4274 
4275       if (PrintTerminationStats) {
4276         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4277         size_t lab_waste;
4278         size_t lab_undo_waste;
4279         pss->waste(lab_waste, lab_undo_waste);
4280         _g1h->print_termination_stats(gclog_or_tty,
4281                                       worker_id,
4282                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
4283                                       strong_roots_sec * 1000.0,                  /* strong roots time */
4284                                       term_sec * 1000.0,                          /* evac term time */
4285                                       evac_term_attempts,                         /* evac term attempts */
4286                                       lab_waste,                                  /* alloc buffer waste */
4287                                       lab_undo_waste                              /* undo waste */
4288                                       );
4289       }
4290 
4291       // Close the inner scope so that the ResourceMark and HandleMark
4292       // destructors are executed here and are included as part of the
4293       // "GC Worker Time".
4294     }
4295     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4296   }
4297 };
4298 
4299 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4300   st->print_raw_cr("GC Termination Stats");
4301   st->print_raw_cr("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
4302   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts  total   alloc    undo");
4303   st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4304 }
4305 
4306 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4307                                               uint worker_id,
4308                                               double elapsed_ms,
4309                                               double strong_roots_ms,
4310                                               double term_ms,
4311                                               size_t term_attempts,
4312                                               size_t alloc_buffer_waste,
4313                                               size_t undo_waste) const {
4314   st->print_cr("%3d %9.2f %9.2f %6.2f "
4315                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4316                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4317                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4318                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4319                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4320                alloc_buffer_waste * HeapWordSize / K,
4321                undo_waste * HeapWordSize / K);
4322 }
4323 
4324 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4325 private:
4326   BoolObjectClosure* _is_alive;
4327   int _initial_string_table_size;
4328   int _initial_symbol_table_size;
4329 
4330   bool  _process_strings;
4331   int _strings_processed;
4332   int _strings_removed;
4333 
4334   bool  _process_symbols;
4335   int _symbols_processed;
4336   int _symbols_removed;
4337 
4338 public:
4339   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4340     AbstractGangTask("String/Symbol Unlinking"),
4341     _is_alive(is_alive),
4342     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4343     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4344 
4345     _initial_string_table_size = StringTable::the_table()->table_size();
4346     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4347     if (process_strings) {
4348       StringTable::clear_parallel_claimed_index();
4349     }
4350     if (process_symbols) {
4351       SymbolTable::clear_parallel_claimed_index();
4352     }
4353   }
4354 
4355   ~G1StringSymbolTableUnlinkTask() {
4356     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4357               "claim value %d after unlink less than initial string table size %d",
4358               StringTable::parallel_claimed_index(), _initial_string_table_size);
4359     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4360               "claim value %d after unlink less than initial symbol table size %d",
4361               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4362 
4363     if (G1TraceStringSymbolTableScrubbing) {
4364       gclog_or_tty->print_cr("Cleaned string and symbol table, "
4365                              "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4366                              "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4367                              strings_processed(), strings_removed(),
4368                              symbols_processed(), symbols_removed());
4369     }
4370   }
4371 
4372   void work(uint worker_id) {
4373     int strings_processed = 0;
4374     int strings_removed = 0;
4375     int symbols_processed = 0;
4376     int symbols_removed = 0;
4377     if (_process_strings) {
4378       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4379       Atomic::add(strings_processed, &_strings_processed);
4380       Atomic::add(strings_removed, &_strings_removed);
4381     }
4382     if (_process_symbols) {
4383       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4384       Atomic::add(symbols_processed, &_symbols_processed);
4385       Atomic::add(symbols_removed, &_symbols_removed);
4386     }
4387   }
4388 
4389   size_t strings_processed() const { return (size_t)_strings_processed; }
4390   size_t strings_removed()   const { return (size_t)_strings_removed; }
4391 
4392   size_t symbols_processed() const { return (size_t)_symbols_processed; }
4393   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
4394 };
4395 
4396 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4397 private:
4398   static Monitor* _lock;
4399 
4400   BoolObjectClosure* const _is_alive;
4401   const bool               _unloading_occurred;
4402   const uint               _num_workers;
4403 
4404   // Variables used to claim nmethods.
4405   nmethod* _first_nmethod;
4406   volatile nmethod* _claimed_nmethod;
4407 
4408   // The list of nmethods that need to be processed by the second pass.
4409   volatile nmethod* _postponed_list;
4410   volatile uint     _num_entered_barrier;
4411 
4412  public:
4413   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4414       _is_alive(is_alive),
4415       _unloading_occurred(unloading_occurred),
4416       _num_workers(num_workers),
4417       _first_nmethod(NULL),
4418       _claimed_nmethod(NULL),
4419       _postponed_list(NULL),
4420       _num_entered_barrier(0)
4421   {
4422     nmethod::increase_unloading_clock();
4423     // Get first alive nmethod
4424     NMethodIterator iter = NMethodIterator();
4425     if(iter.next_alive()) {
4426       _first_nmethod = iter.method();
4427     }
4428     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4429   }
4430 
4431   ~G1CodeCacheUnloadingTask() {
4432     CodeCache::verify_clean_inline_caches();
4433 
4434     CodeCache::set_needs_cache_clean(false);
4435     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4436 
4437     CodeCache::verify_icholder_relocations();
4438   }
4439 
4440  private:
4441   void add_to_postponed_list(nmethod* nm) {
4442       nmethod* old;
4443       do {
4444         old = (nmethod*)_postponed_list;
4445         nm->set_unloading_next(old);
4446       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4447   }
4448 
4449   void clean_nmethod(nmethod* nm) {
4450     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4451 
4452     if (postponed) {
4453       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4454       add_to_postponed_list(nm);
4455     }
4456 
4457     // Mark that this thread has been cleaned/unloaded.
4458     // After this call, it will be safe to ask if this nmethod was unloaded or not.
4459     nm->set_unloading_clock(nmethod::global_unloading_clock());
4460   }
4461 
4462   void clean_nmethod_postponed(nmethod* nm) {
4463     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4464   }
4465 
4466   static const int MaxClaimNmethods = 16;
4467 
4468   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4469     nmethod* first;
4470     NMethodIterator last;
4471 
4472     do {
4473       *num_claimed_nmethods = 0;
4474 
4475       first = (nmethod*)_claimed_nmethod;
4476       last = NMethodIterator(first);
4477 
4478       if (first != NULL) {
4479 
4480         for (int i = 0; i < MaxClaimNmethods; i++) {
4481           if (!last.next_alive()) {
4482             break;
4483           }
4484           claimed_nmethods[i] = last.method();
4485           (*num_claimed_nmethods)++;
4486         }
4487       }
4488 
4489     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4490   }
4491 
4492   nmethod* claim_postponed_nmethod() {
4493     nmethod* claim;
4494     nmethod* next;
4495 
4496     do {
4497       claim = (nmethod*)_postponed_list;
4498       if (claim == NULL) {
4499         return NULL;
4500       }
4501 
4502       next = claim->unloading_next();
4503 
4504     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4505 
4506     return claim;
4507   }
4508 
4509  public:
4510   // Mark that we're done with the first pass of nmethod cleaning.
4511   void barrier_mark(uint worker_id) {
4512     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4513     _num_entered_barrier++;
4514     if (_num_entered_barrier == _num_workers) {
4515       ml.notify_all();
4516     }
4517   }
4518 
4519   // See if we have to wait for the other workers to
4520   // finish their first-pass nmethod cleaning work.
4521   void barrier_wait(uint worker_id) {
4522     if (_num_entered_barrier < _num_workers) {
4523       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4524       while (_num_entered_barrier < _num_workers) {
4525           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4526       }
4527     }
4528   }
4529 
4530   // Cleaning and unloading of nmethods. Some work has to be postponed
4531   // to the second pass, when we know which nmethods survive.
4532   void work_first_pass(uint worker_id) {
4533     // The first nmethods is claimed by the first worker.
4534     if (worker_id == 0 && _first_nmethod != NULL) {
4535       clean_nmethod(_first_nmethod);
4536       _first_nmethod = NULL;
4537     }
4538 
4539     int num_claimed_nmethods;
4540     nmethod* claimed_nmethods[MaxClaimNmethods];
4541 
4542     while (true) {
4543       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4544 
4545       if (num_claimed_nmethods == 0) {
4546         break;
4547       }
4548 
4549       for (int i = 0; i < num_claimed_nmethods; i++) {
4550         clean_nmethod(claimed_nmethods[i]);
4551       }
4552     }
4553   }
4554 
4555   void work_second_pass(uint worker_id) {
4556     nmethod* nm;
4557     // Take care of postponed nmethods.
4558     while ((nm = claim_postponed_nmethod()) != NULL) {
4559       clean_nmethod_postponed(nm);
4560     }
4561   }
4562 };
4563 
4564 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4565 
4566 class G1KlassCleaningTask : public StackObj {
4567   BoolObjectClosure*                      _is_alive;
4568   volatile jint                           _clean_klass_tree_claimed;
4569   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4570 
4571  public:
4572   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4573       _is_alive(is_alive),
4574       _clean_klass_tree_claimed(0),
4575       _klass_iterator() {
4576   }
4577 
4578  private:
4579   bool claim_clean_klass_tree_task() {
4580     if (_clean_klass_tree_claimed) {
4581       return false;
4582     }
4583 
4584     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4585   }
4586 
4587   InstanceKlass* claim_next_klass() {
4588     Klass* klass;
4589     do {
4590       klass =_klass_iterator.next_klass();
4591     } while (klass != NULL && !klass->is_instance_klass());
4592 
4593     // this can be null so don't call InstanceKlass::cast
4594     return static_cast<InstanceKlass*>(klass);
4595   }
4596 
4597 public:
4598 
4599   void clean_klass(InstanceKlass* ik) {
4600     ik->clean_weak_instanceklass_links(_is_alive);
4601   }
4602 
4603   void work() {
4604     ResourceMark rm;
4605 
4606     // One worker will clean the subklass/sibling klass tree.
4607     if (claim_clean_klass_tree_task()) {
4608       Klass::clean_subklass_tree(_is_alive);
4609     }
4610 
4611     // All workers will help cleaning the classes,
4612     InstanceKlass* klass;
4613     while ((klass = claim_next_klass()) != NULL) {
4614       clean_klass(klass);
4615     }
4616   }
4617 };
4618 
4619 // To minimize the remark pause times, the tasks below are done in parallel.
4620 class G1ParallelCleaningTask : public AbstractGangTask {
4621 private:
4622   G1StringSymbolTableUnlinkTask _string_symbol_task;
4623   G1CodeCacheUnloadingTask      _code_cache_task;
4624   G1KlassCleaningTask           _klass_cleaning_task;
4625 
4626 public:
4627   // The constructor is run in the VMThread.
4628   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4629       AbstractGangTask("Parallel Cleaning"),
4630       _string_symbol_task(is_alive, process_strings, process_symbols),
4631       _code_cache_task(num_workers, is_alive, unloading_occurred),
4632       _klass_cleaning_task(is_alive) {
4633   }
4634 
4635   // The parallel work done by all worker threads.
4636   void work(uint worker_id) {
4637     // Do first pass of code cache cleaning.
4638     _code_cache_task.work_first_pass(worker_id);
4639 
4640     // Let the threads mark that the first pass is done.
4641     _code_cache_task.barrier_mark(worker_id);
4642 
4643     // Clean the Strings and Symbols.
4644     _string_symbol_task.work(worker_id);
4645 
4646     // Wait for all workers to finish the first code cache cleaning pass.
4647     _code_cache_task.barrier_wait(worker_id);
4648 
4649     // Do the second code cache cleaning work, which realize on
4650     // the liveness information gathered during the first pass.
4651     _code_cache_task.work_second_pass(worker_id);
4652 
4653     // Clean all klasses that were not unloaded.
4654     _klass_cleaning_task.work();
4655   }
4656 };
4657 
4658 
4659 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4660                                         bool process_strings,
4661                                         bool process_symbols,
4662                                         bool class_unloading_occurred) {
4663   uint n_workers = workers()->active_workers();
4664 
4665   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4666                                         n_workers, class_unloading_occurred);
4667   workers()->run_task(&g1_unlink_task);
4668 }
4669 
4670 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4671                                                      bool process_strings, bool process_symbols) {
4672   {
4673     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4674     workers()->run_task(&g1_unlink_task);
4675   }
4676 
4677   if (G1StringDedup::is_enabled()) {
4678     G1StringDedup::unlink(is_alive);
4679   }
4680 }
4681 
4682 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4683  private:
4684   DirtyCardQueueSet* _queue;
4685  public:
4686   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4687 
4688   virtual void work(uint worker_id) {
4689     G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4690     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4691 
4692     RedirtyLoggedCardTableEntryClosure cl;
4693     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4694 
4695     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4696   }
4697 };
4698 
4699 void G1CollectedHeap::redirty_logged_cards() {
4700   double redirty_logged_cards_start = os::elapsedTime();
4701 
4702   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4703   dirty_card_queue_set().reset_for_par_iteration();
4704   workers()->run_task(&redirty_task);
4705 
4706   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4707   dcq.merge_bufferlists(&dirty_card_queue_set());
4708   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4709 
4710   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4711 }
4712 
4713 // Weak Reference Processing support
4714 
4715 // An always "is_alive" closure that is used to preserve referents.
4716 // If the object is non-null then it's alive.  Used in the preservation
4717 // of referent objects that are pointed to by reference objects
4718 // discovered by the CM ref processor.
4719 class G1AlwaysAliveClosure: public BoolObjectClosure {
4720   G1CollectedHeap* _g1;
4721 public:
4722   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4723   bool do_object_b(oop p) {
4724     if (p != NULL) {
4725       return true;
4726     }
4727     return false;
4728   }
4729 };
4730 
4731 bool G1STWIsAliveClosure::do_object_b(oop p) {
4732   // An object is reachable if it is outside the collection set,
4733   // or is inside and copied.
4734   return !_g1->is_in_cset(p) || p->is_forwarded();
4735 }
4736 
4737 // Non Copying Keep Alive closure
4738 class G1KeepAliveClosure: public OopClosure {
4739   G1CollectedHeap* _g1;
4740 public:
4741   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4742   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4743   void do_oop(oop* p) {
4744     oop obj = *p;
4745     assert(obj != NULL, "the caller should have filtered out NULL values");
4746 
4747     const InCSetState cset_state = _g1->in_cset_state(obj);
4748     if (!cset_state.is_in_cset_or_humongous()) {
4749       return;
4750     }
4751     if (cset_state.is_in_cset()) {
4752       assert( obj->is_forwarded(), "invariant" );
4753       *p = obj->forwardee();
4754     } else {
4755       assert(!obj->is_forwarded(), "invariant" );
4756       assert(cset_state.is_humongous(),
4757              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4758       _g1->set_humongous_is_live(obj);
4759     }
4760   }
4761 };
4762 
4763 // Copying Keep Alive closure - can be called from both
4764 // serial and parallel code as long as different worker
4765 // threads utilize different G1ParScanThreadState instances
4766 // and different queues.
4767 
4768 class G1CopyingKeepAliveClosure: public OopClosure {
4769   G1CollectedHeap*         _g1h;
4770   OopClosure*              _copy_non_heap_obj_cl;
4771   G1ParScanThreadState*    _par_scan_state;
4772 
4773 public:
4774   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4775                             OopClosure* non_heap_obj_cl,
4776                             G1ParScanThreadState* pss):
4777     _g1h(g1h),
4778     _copy_non_heap_obj_cl(non_heap_obj_cl),
4779     _par_scan_state(pss)
4780   {}
4781 
4782   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4783   virtual void do_oop(      oop* p) { do_oop_work(p); }
4784 
4785   template <class T> void do_oop_work(T* p) {
4786     oop obj = oopDesc::load_decode_heap_oop(p);
4787 
4788     if (_g1h->is_in_cset_or_humongous(obj)) {
4789       // If the referent object has been forwarded (either copied
4790       // to a new location or to itself in the event of an
4791       // evacuation failure) then we need to update the reference
4792       // field and, if both reference and referent are in the G1
4793       // heap, update the RSet for the referent.
4794       //
4795       // If the referent has not been forwarded then we have to keep
4796       // it alive by policy. Therefore we have copy the referent.
4797       //
4798       // If the reference field is in the G1 heap then we can push
4799       // on the PSS queue. When the queue is drained (after each
4800       // phase of reference processing) the object and it's followers
4801       // will be copied, the reference field set to point to the
4802       // new location, and the RSet updated. Otherwise we need to
4803       // use the the non-heap or metadata closures directly to copy
4804       // the referent object and update the pointer, while avoiding
4805       // updating the RSet.
4806 
4807       if (_g1h->is_in_g1_reserved(p)) {
4808         _par_scan_state->push_on_queue(p);
4809       } else {
4810         assert(!Metaspace::contains((const void*)p),
4811                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4812         _copy_non_heap_obj_cl->do_oop(p);
4813       }
4814     }
4815   }
4816 };
4817 
4818 // Serial drain queue closure. Called as the 'complete_gc'
4819 // closure for each discovered list in some of the
4820 // reference processing phases.
4821 
4822 class G1STWDrainQueueClosure: public VoidClosure {
4823 protected:
4824   G1CollectedHeap* _g1h;
4825   G1ParScanThreadState* _par_scan_state;
4826 
4827   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4828 
4829 public:
4830   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4831     _g1h(g1h),
4832     _par_scan_state(pss)
4833   { }
4834 
4835   void do_void() {
4836     G1ParScanThreadState* const pss = par_scan_state();
4837     pss->trim_queue();
4838   }
4839 };
4840 
4841 // Parallel Reference Processing closures
4842 
4843 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4844 // processing during G1 evacuation pauses.
4845 
4846 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4847 private:
4848   G1CollectedHeap*          _g1h;
4849   G1ParScanThreadStateSet*  _pss;
4850   RefToScanQueueSet*        _queues;
4851   WorkGang*                 _workers;
4852   uint                      _active_workers;
4853 
4854 public:
4855   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4856                            G1ParScanThreadStateSet* per_thread_states,
4857                            WorkGang* workers,
4858                            RefToScanQueueSet *task_queues,
4859                            uint n_workers) :
4860     _g1h(g1h),
4861     _pss(per_thread_states),
4862     _queues(task_queues),
4863     _workers(workers),
4864     _active_workers(n_workers)
4865   {
4866     assert(n_workers > 0, "shouldn't call this otherwise");
4867   }
4868 
4869   // Executes the given task using concurrent marking worker threads.
4870   virtual void execute(ProcessTask& task);
4871   virtual void execute(EnqueueTask& task);
4872 };
4873 
4874 // Gang task for possibly parallel reference processing
4875 
4876 class G1STWRefProcTaskProxy: public AbstractGangTask {
4877   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4878   ProcessTask&     _proc_task;
4879   G1CollectedHeap* _g1h;
4880   G1ParScanThreadStateSet* _pss;
4881   RefToScanQueueSet* _task_queues;
4882   ParallelTaskTerminator* _terminator;
4883 
4884 public:
4885   G1STWRefProcTaskProxy(ProcessTask& proc_task,
4886                         G1CollectedHeap* g1h,
4887                         G1ParScanThreadStateSet* per_thread_states,
4888                         RefToScanQueueSet *task_queues,
4889                         ParallelTaskTerminator* terminator) :
4890     AbstractGangTask("Process reference objects in parallel"),
4891     _proc_task(proc_task),
4892     _g1h(g1h),
4893     _pss(per_thread_states),
4894     _task_queues(task_queues),
4895     _terminator(terminator)
4896   {}
4897 
4898   virtual void work(uint worker_id) {
4899     // The reference processing task executed by a single worker.
4900     ResourceMark rm;
4901     HandleMark   hm;
4902 
4903     G1STWIsAliveClosure is_alive(_g1h);
4904 
4905     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4906     pss->set_ref_processor(NULL);
4907 
4908     // Keep alive closure.
4909     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4910 
4911     // Complete GC closure
4912     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4913 
4914     // Call the reference processing task's work routine.
4915     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4916 
4917     // Note we cannot assert that the refs array is empty here as not all
4918     // of the processing tasks (specifically phase2 - pp2_work) execute
4919     // the complete_gc closure (which ordinarily would drain the queue) so
4920     // the queue may not be empty.
4921   }
4922 };
4923 
4924 // Driver routine for parallel reference processing.
4925 // Creates an instance of the ref processing gang
4926 // task and has the worker threads execute it.
4927 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4928   assert(_workers != NULL, "Need parallel worker threads.");
4929 
4930   ParallelTaskTerminator terminator(_active_workers, _queues);
4931   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4932 
4933   _workers->run_task(&proc_task_proxy);
4934 }
4935 
4936 // Gang task for parallel reference enqueueing.
4937 
4938 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4939   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4940   EnqueueTask& _enq_task;
4941 
4942 public:
4943   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4944     AbstractGangTask("Enqueue reference objects in parallel"),
4945     _enq_task(enq_task)
4946   { }
4947 
4948   virtual void work(uint worker_id) {
4949     _enq_task.work(worker_id);
4950   }
4951 };
4952 
4953 // Driver routine for parallel reference enqueueing.
4954 // Creates an instance of the ref enqueueing gang
4955 // task and has the worker threads execute it.
4956 
4957 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4958   assert(_workers != NULL, "Need parallel worker threads.");
4959 
4960   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4961 
4962   _workers->run_task(&enq_task_proxy);
4963 }
4964 
4965 // End of weak reference support closures
4966 
4967 // Abstract task used to preserve (i.e. copy) any referent objects
4968 // that are in the collection set and are pointed to by reference
4969 // objects discovered by the CM ref processor.
4970 
4971 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4972 protected:
4973   G1CollectedHeap*         _g1h;
4974   G1ParScanThreadStateSet* _pss;
4975   RefToScanQueueSet*       _queues;
4976   ParallelTaskTerminator   _terminator;
4977   uint                     _n_workers;
4978 
4979 public:
4980   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4981     AbstractGangTask("ParPreserveCMReferents"),
4982     _g1h(g1h),
4983     _pss(per_thread_states),
4984     _queues(task_queues),
4985     _terminator(workers, _queues),
4986     _n_workers(workers)
4987   { }
4988 
4989   void work(uint worker_id) {
4990     ResourceMark rm;
4991     HandleMark   hm;
4992 
4993     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4994     pss->set_ref_processor(NULL);
4995     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4996 
4997     // Is alive closure
4998     G1AlwaysAliveClosure always_alive(_g1h);
4999 
5000     // Copying keep alive closure. Applied to referent objects that need
5001     // to be copied.
5002     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
5003 
5004     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5005 
5006     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5007     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5008 
5009     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5010     // So this must be true - but assert just in case someone decides to
5011     // change the worker ids.
5012     assert(worker_id < limit, "sanity");
5013     assert(!rp->discovery_is_atomic(), "check this code");
5014 
5015     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5016     for (uint idx = worker_id; idx < limit; idx += stride) {
5017       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5018 
5019       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5020       while (iter.has_next()) {
5021         // Since discovery is not atomic for the CM ref processor, we
5022         // can see some null referent objects.
5023         iter.load_ptrs(DEBUG_ONLY(true));
5024         oop ref = iter.obj();
5025 
5026         // This will filter nulls.
5027         if (iter.is_referent_alive()) {
5028           iter.make_referent_alive();
5029         }
5030         iter.move_to_next();
5031       }
5032     }
5033 
5034     // Drain the queue - which may cause stealing
5035     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5036     drain_queue.do_void();
5037     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5038     assert(pss->queue_is_empty(), "should be");
5039   }
5040 };
5041 
5042 // Weak Reference processing during an evacuation pause (part 1).
5043 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5044   double ref_proc_start = os::elapsedTime();
5045 
5046   ReferenceProcessor* rp = _ref_processor_stw;
5047   assert(rp->discovery_enabled(), "should have been enabled");
5048 
5049   // Any reference objects, in the collection set, that were 'discovered'
5050   // by the CM ref processor should have already been copied (either by
5051   // applying the external root copy closure to the discovered lists, or
5052   // by following an RSet entry).
5053   //
5054   // But some of the referents, that are in the collection set, that these
5055   // reference objects point to may not have been copied: the STW ref
5056   // processor would have seen that the reference object had already
5057   // been 'discovered' and would have skipped discovering the reference,
5058   // but would not have treated the reference object as a regular oop.
5059   // As a result the copy closure would not have been applied to the
5060   // referent object.
5061   //
5062   // We need to explicitly copy these referent objects - the references
5063   // will be processed at the end of remarking.
5064   //
5065   // We also need to do this copying before we process the reference
5066   // objects discovered by the STW ref processor in case one of these
5067   // referents points to another object which is also referenced by an
5068   // object discovered by the STW ref processor.
5069 
5070   uint no_of_gc_workers = workers()->active_workers();
5071 
5072   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5073                                                  per_thread_states,
5074                                                  no_of_gc_workers,
5075                                                  _task_queues);
5076 
5077   workers()->run_task(&keep_cm_referents);
5078 
5079   // Closure to test whether a referent is alive.
5080   G1STWIsAliveClosure is_alive(this);
5081 
5082   // Even when parallel reference processing is enabled, the processing
5083   // of JNI refs is serial and performed serially by the current thread
5084   // rather than by a worker. The following PSS will be used for processing
5085   // JNI refs.
5086 
5087   // Use only a single queue for this PSS.
5088   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
5089   pss->set_ref_processor(NULL);
5090   assert(pss->queue_is_empty(), "pre-condition");
5091 
5092   // Keep alive closure.
5093   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5094 
5095   // Serial Complete GC closure
5096   G1STWDrainQueueClosure drain_queue(this, pss);
5097 
5098   // Setup the soft refs policy...
5099   rp->setup_policy(false);
5100 
5101   ReferenceProcessorStats stats;
5102   if (!rp->processing_is_mt()) {
5103     // Serial reference processing...
5104     stats = rp->process_discovered_references(&is_alive,
5105                                               &keep_alive,
5106                                               &drain_queue,
5107                                               NULL,
5108                                               _gc_timer_stw);
5109   } else {
5110     // Parallel reference processing
5111     assert(rp->num_q() == no_of_gc_workers, "sanity");
5112     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5113 
5114     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5115     stats = rp->process_discovered_references(&is_alive,
5116                                               &keep_alive,
5117                                               &drain_queue,
5118                                               &par_task_executor,
5119                                               _gc_timer_stw);
5120   }
5121 
5122   _gc_tracer_stw->report_gc_reference_stats(stats);
5123 
5124   // We have completed copying any necessary live referent objects.
5125   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5126 
5127   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5128   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5129 }
5130 
5131 // Weak Reference processing during an evacuation pause (part 2).
5132 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5133   double ref_enq_start = os::elapsedTime();
5134 
5135   ReferenceProcessor* rp = _ref_processor_stw;
5136   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5137 
5138   // Now enqueue any remaining on the discovered lists on to
5139   // the pending list.
5140   if (!rp->processing_is_mt()) {
5141     // Serial reference processing...
5142     rp->enqueue_discovered_references();
5143   } else {
5144     // Parallel reference enqueueing
5145 
5146     uint n_workers = workers()->active_workers();
5147 
5148     assert(rp->num_q() == n_workers, "sanity");
5149     assert(n_workers <= rp->max_num_q(), "sanity");
5150 
5151     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5152     rp->enqueue_discovered_references(&par_task_executor);
5153   }
5154 
5155   rp->verify_no_references_recorded();
5156   assert(!rp->discovery_enabled(), "should have been disabled");
5157 
5158   // FIXME
5159   // CM's reference processing also cleans up the string and symbol tables.
5160   // Should we do that here also? We could, but it is a serial operation
5161   // and could significantly increase the pause time.
5162 
5163   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5164   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5165 }
5166 
5167 void G1CollectedHeap::pre_evacuate_collection_set() {
5168   _expand_heap_after_alloc_failure = true;
5169   _evacuation_failed = false;
5170 
5171   // Disable the hot card cache.
5172   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5173   hot_card_cache->reset_hot_cache_claimed_index();
5174   hot_card_cache->set_use_cache(false);
5175 
5176 }
5177 
5178 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5179   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5180 
5181   // Should G1EvacuationFailureALot be in effect for this GC?
5182   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5183 
5184   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5185   double start_par_time_sec = os::elapsedTime();
5186   double end_par_time_sec;
5187 
5188   {
5189     const uint n_workers = workers()->active_workers();
5190     G1RootProcessor root_processor(this, n_workers);
5191     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5192     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5193     if (collector_state()->during_initial_mark_pause()) {
5194       ClassLoaderDataGraph::clear_claimed_marks();
5195     }
5196 
5197     // The individual threads will set their evac-failure closures.
5198     if (PrintTerminationStats) {
5199       print_termination_stats_hdr(gclog_or_tty);
5200     }
5201 
5202     workers()->run_task(&g1_par_task);
5203     end_par_time_sec = os::elapsedTime();
5204 
5205     // Closing the inner scope will execute the destructor
5206     // for the G1RootProcessor object. We record the current
5207     // elapsed time before closing the scope so that time
5208     // taken for the destructor is NOT included in the
5209     // reported parallel time.
5210   }
5211 
5212   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5213 
5214   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5215   phase_times->record_par_time(par_time_ms);
5216 
5217   double code_root_fixup_time_ms =
5218         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5219   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5220 
5221   // Process any discovered reference objects - we have
5222   // to do this _before_ we retire the GC alloc regions
5223   // as we may have to copy some 'reachable' referent
5224   // objects (and their reachable sub-graphs) that were
5225   // not copied during the pause.
5226   process_discovered_references(per_thread_states);
5227 
5228   if (G1StringDedup::is_enabled()) {
5229     double fixup_start = os::elapsedTime();
5230 
5231     G1STWIsAliveClosure is_alive(this);
5232     G1KeepAliveClosure keep_alive(this);
5233     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5234 
5235     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5236     phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5237   }
5238 
5239   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5240 
5241   if (evacuation_failed()) {
5242     remove_self_forwarding_pointers();
5243 
5244     // Reset the G1EvacuationFailureALot counters and flags
5245     // Note: the values are reset only when an actual
5246     // evacuation failure occurs.
5247     NOT_PRODUCT(reset_evacuation_should_fail();)
5248   }
5249 
5250   // Enqueue any remaining references remaining on the STW
5251   // reference processor's discovered lists. We need to do
5252   // this after the card table is cleaned (and verified) as
5253   // the act of enqueueing entries on to the pending list
5254   // will log these updates (and dirty their associated
5255   // cards). We need these updates logged to update any
5256   // RSets.
5257   enqueue_discovered_references(per_thread_states);
5258 }
5259 
5260 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5261   _allocator->release_gc_alloc_regions(evacuation_info);
5262 
5263   per_thread_states->flush();
5264 
5265   record_obj_copy_mem_stats();
5266 
5267   // Reset and re-enable the hot card cache.
5268   // Note the counts for the cards in the regions in the
5269   // collection set are reset when the collection set is freed.
5270   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5271   hot_card_cache->reset_hot_cache();
5272   hot_card_cache->set_use_cache(true);
5273 
5274   purge_code_root_memory();
5275 
5276   redirty_logged_cards();
5277 #if defined(COMPILER2) || INCLUDE_JVMCI
5278   DerivedPointerTable::update_pointers();
5279 #endif
5280 }
5281 
5282 void G1CollectedHeap::record_obj_copy_mem_stats() {
5283   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5284                                                create_g1_evac_summary(&_old_evac_stats));
5285 }
5286 
5287 void G1CollectedHeap::free_region(HeapRegion* hr,
5288                                   FreeRegionList* free_list,
5289                                   bool par,
5290                                   bool locked) {
5291   assert(!hr->is_free(), "the region should not be free");
5292   assert(!hr->is_empty(), "the region should not be empty");
5293   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5294   assert(free_list != NULL, "pre-condition");
5295 
5296   if (G1VerifyBitmaps) {
5297     MemRegion mr(hr->bottom(), hr->end());
5298     concurrent_mark()->clearRangePrevBitmap(mr);
5299   }
5300 
5301   // Clear the card counts for this region.
5302   // Note: we only need to do this if the region is not young
5303   // (since we don't refine cards in young regions).
5304   if (!hr->is_young()) {
5305     _cg1r->hot_card_cache()->reset_card_counts(hr);
5306   }
5307   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5308   free_list->add_ordered(hr);
5309 }
5310 
5311 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5312                                      FreeRegionList* free_list,
5313                                      bool par) {
5314   assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5315   assert(free_list != NULL, "pre-condition");
5316 
5317   size_t hr_capacity = hr->capacity();
5318   // We need to read this before we make the region non-humongous,
5319   // otherwise the information will be gone.
5320   uint last_index = hr->last_hc_index();
5321   hr->clear_humongous();
5322   free_region(hr, free_list, par);
5323 
5324   uint i = hr->hrm_index() + 1;
5325   while (i < last_index) {
5326     HeapRegion* curr_hr = region_at(i);
5327     assert(curr_hr->is_continues_humongous(), "invariant");
5328     curr_hr->clear_humongous();
5329     free_region(curr_hr, free_list, par);
5330     i += 1;
5331   }
5332 }
5333 
5334 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5335                                        const HeapRegionSetCount& humongous_regions_removed) {
5336   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5337     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5338     _old_set.bulk_remove(old_regions_removed);
5339     _humongous_set.bulk_remove(humongous_regions_removed);
5340   }
5341 
5342 }
5343 
5344 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5345   assert(list != NULL, "list can't be null");
5346   if (!list->is_empty()) {
5347     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5348     _hrm.insert_list_into_free_list(list);
5349   }
5350 }
5351 
5352 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5353   decrease_used(bytes);
5354 }
5355 
5356 class G1ParCleanupCTTask : public AbstractGangTask {
5357   G1SATBCardTableModRefBS* _ct_bs;
5358   G1CollectedHeap* _g1h;
5359   HeapRegion* volatile _su_head;
5360 public:
5361   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5362                      G1CollectedHeap* g1h) :
5363     AbstractGangTask("G1 Par Cleanup CT Task"),
5364     _ct_bs(ct_bs), _g1h(g1h) { }
5365 
5366   void work(uint worker_id) {
5367     HeapRegion* r;
5368     while (r = _g1h->pop_dirty_cards_region()) {
5369       clear_cards(r);
5370     }
5371   }
5372 
5373   void clear_cards(HeapRegion* r) {
5374     // Cards of the survivors should have already been dirtied.
5375     if (!r->is_survivor()) {
5376       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5377     }
5378   }
5379 };
5380 
5381 #ifndef PRODUCT
5382 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5383   G1CollectedHeap* _g1h;
5384   G1SATBCardTableModRefBS* _ct_bs;
5385 public:
5386   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5387     : _g1h(g1h), _ct_bs(ct_bs) { }
5388   virtual bool doHeapRegion(HeapRegion* r) {
5389     if (r->is_survivor()) {
5390       _g1h->verify_dirty_region(r);
5391     } else {
5392       _g1h->verify_not_dirty_region(r);
5393     }
5394     return false;
5395   }
5396 };
5397 
5398 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5399   // All of the region should be clean.
5400   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5401   MemRegion mr(hr->bottom(), hr->end());
5402   ct_bs->verify_not_dirty_region(mr);
5403 }
5404 
5405 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5406   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5407   // dirty allocated blocks as they allocate them. The thread that
5408   // retires each region and replaces it with a new one will do a
5409   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5410   // not dirty that area (one less thing to have to do while holding
5411   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5412   // is dirty.
5413   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5414   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5415   if (hr->is_young()) {
5416     ct_bs->verify_g1_young_region(mr);
5417   } else {
5418     ct_bs->verify_dirty_region(mr);
5419   }
5420 }
5421 
5422 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5423   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5424   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5425     verify_dirty_region(hr);
5426   }
5427 }
5428 
5429 void G1CollectedHeap::verify_dirty_young_regions() {
5430   verify_dirty_young_list(_young_list->first_region());
5431 }
5432 
5433 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5434                                                HeapWord* tams, HeapWord* end) {
5435   guarantee(tams <= end,
5436             "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5437   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5438   if (result < end) {
5439     gclog_or_tty->cr();
5440     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5441                            bitmap_name, p2i(result));
5442     gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5443                            bitmap_name, p2i(tams), p2i(end));
5444     return false;
5445   }
5446   return true;
5447 }
5448 
5449 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5450   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5451   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5452 
5453   HeapWord* bottom = hr->bottom();
5454   HeapWord* ptams  = hr->prev_top_at_mark_start();
5455   HeapWord* ntams  = hr->next_top_at_mark_start();
5456   HeapWord* end    = hr->end();
5457 
5458   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5459 
5460   bool res_n = true;
5461   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5462   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5463   // if we happen to be in that state.
5464   if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5465     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5466   }
5467   if (!res_p || !res_n) {
5468     gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5469                            HR_FORMAT_PARAMS(hr));
5470     gclog_or_tty->print_cr("#### Caller: %s", caller);
5471     return false;
5472   }
5473   return true;
5474 }
5475 
5476 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5477   if (!G1VerifyBitmaps) return;
5478 
5479   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5480 }
5481 
5482 class G1VerifyBitmapClosure : public HeapRegionClosure {
5483 private:
5484   const char* _caller;
5485   G1CollectedHeap* _g1h;
5486   bool _failures;
5487 
5488 public:
5489   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5490     _caller(caller), _g1h(g1h), _failures(false) { }
5491 
5492   bool failures() { return _failures; }
5493 
5494   virtual bool doHeapRegion(HeapRegion* hr) {
5495     if (hr->is_continues_humongous()) return false;
5496 
5497     bool result = _g1h->verify_bitmaps(_caller, hr);
5498     if (!result) {
5499       _failures = true;
5500     }
5501     return false;
5502   }
5503 };
5504 
5505 void G1CollectedHeap::check_bitmaps(const char* caller) {
5506   if (!G1VerifyBitmaps) return;
5507 
5508   G1VerifyBitmapClosure cl(caller, this);
5509   heap_region_iterate(&cl);
5510   guarantee(!cl.failures(), "bitmap verification");
5511 }
5512 
5513 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5514  private:
5515   bool _failures;
5516  public:
5517   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5518 
5519   virtual bool doHeapRegion(HeapRegion* hr) {
5520     uint i = hr->hrm_index();
5521     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5522     if (hr->is_humongous()) {
5523       if (hr->in_collection_set()) {
5524         gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5525         _failures = true;
5526         return true;
5527       }
5528       if (cset_state.is_in_cset()) {
5529         gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5530         _failures = true;
5531         return true;
5532       }
5533       if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5534         gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5535         _failures = true;
5536         return true;
5537       }
5538     } else {
5539       if (cset_state.is_humongous()) {
5540         gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5541         _failures = true;
5542         return true;
5543       }
5544       if (hr->in_collection_set() != cset_state.is_in_cset()) {
5545         gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5546                                hr->in_collection_set(), cset_state.value(), i);
5547         _failures = true;
5548         return true;
5549       }
5550       if (cset_state.is_in_cset()) {
5551         if (hr->is_young() != (cset_state.is_young())) {
5552           gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5553                                  hr->is_young(), cset_state.value(), i);
5554           _failures = true;
5555           return true;
5556         }
5557         if (hr->is_old() != (cset_state.is_old())) {
5558           gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5559                                  hr->is_old(), cset_state.value(), i);
5560           _failures = true;
5561           return true;
5562         }
5563       }
5564     }
5565     return false;
5566   }
5567 
5568   bool failures() const { return _failures; }
5569 };
5570 
5571 bool G1CollectedHeap::check_cset_fast_test() {
5572   G1CheckCSetFastTableClosure cl;
5573   _hrm.iterate(&cl);
5574   return !cl.failures();
5575 }
5576 #endif // PRODUCT
5577 
5578 void G1CollectedHeap::cleanUpCardTable() {
5579   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5580   double start = os::elapsedTime();
5581 
5582   {
5583     // Iterate over the dirty cards region list.
5584     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5585 
5586     workers()->run_task(&cleanup_task);
5587 #ifndef PRODUCT
5588     if (G1VerifyCTCleanup || VerifyAfterGC) {
5589       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5590       heap_region_iterate(&cleanup_verifier);
5591     }
5592 #endif
5593   }
5594 
5595   double elapsed = os::elapsedTime() - start;
5596   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5597 }
5598 
5599 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5600   size_t pre_used = 0;
5601   FreeRegionList local_free_list("Local List for CSet Freeing");
5602 
5603   double young_time_ms     = 0.0;
5604   double non_young_time_ms = 0.0;
5605 
5606   // Since the collection set is a superset of the the young list,
5607   // all we need to do to clear the young list is clear its
5608   // head and length, and unlink any young regions in the code below
5609   _young_list->clear();
5610 
5611   G1CollectorPolicy* policy = g1_policy();
5612 
5613   double start_sec = os::elapsedTime();
5614   bool non_young = true;
5615 
5616   HeapRegion* cur = cs_head;
5617   int age_bound = -1;
5618   size_t rs_lengths = 0;
5619 
5620   while (cur != NULL) {
5621     assert(!is_on_master_free_list(cur), "sanity");
5622     if (non_young) {
5623       if (cur->is_young()) {
5624         double end_sec = os::elapsedTime();
5625         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5626         non_young_time_ms += elapsed_ms;
5627 
5628         start_sec = os::elapsedTime();
5629         non_young = false;
5630       }
5631     } else {
5632       if (!cur->is_young()) {
5633         double end_sec = os::elapsedTime();
5634         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5635         young_time_ms += elapsed_ms;
5636 
5637         start_sec = os::elapsedTime();
5638         non_young = true;
5639       }
5640     }
5641 
5642     rs_lengths += cur->rem_set()->occupied_locked();
5643 
5644     HeapRegion* next = cur->next_in_collection_set();
5645     assert(cur->in_collection_set(), "bad CS");
5646     cur->set_next_in_collection_set(NULL);
5647     clear_in_cset(cur);
5648 
5649     if (cur->is_young()) {
5650       int index = cur->young_index_in_cset();
5651       assert(index != -1, "invariant");
5652       assert((uint) index < policy->young_cset_region_length(), "invariant");
5653       size_t words_survived = surviving_young_words[index];
5654       cur->record_surv_words_in_group(words_survived);
5655 
5656       // At this point the we have 'popped' cur from the collection set
5657       // (linked via next_in_collection_set()) but it is still in the
5658       // young list (linked via next_young_region()). Clear the
5659       // _next_young_region field.
5660       cur->set_next_young_region(NULL);
5661     } else {
5662       int index = cur->young_index_in_cset();
5663       assert(index == -1, "invariant");
5664     }
5665 
5666     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5667             (!cur->is_young() && cur->young_index_in_cset() == -1),
5668             "invariant" );
5669 
5670     if (!cur->evacuation_failed()) {
5671       MemRegion used_mr = cur->used_region();
5672 
5673       // And the region is empty.
5674       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5675       pre_used += cur->used();
5676       free_region(cur, &local_free_list, false /* par */, true /* locked */);
5677     } else {
5678       cur->uninstall_surv_rate_group();
5679       if (cur->is_young()) {
5680         cur->set_young_index_in_cset(-1);
5681       }
5682       cur->set_evacuation_failed(false);
5683       // The region is now considered to be old.
5684       cur->set_old();
5685       // Do some allocation statistics accounting. Regions that failed evacuation
5686       // are always made old, so there is no need to update anything in the young
5687       // gen statistics, but we need to update old gen statistics.
5688       size_t used_words = cur->marked_bytes() / HeapWordSize;
5689       _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5690       _old_set.add(cur);
5691       evacuation_info.increment_collectionset_used_after(cur->used());
5692     }
5693     cur = next;
5694   }
5695 
5696   evacuation_info.set_regions_freed(local_free_list.length());
5697   policy->record_max_rs_lengths(rs_lengths);
5698   policy->cset_regions_freed();
5699 
5700   double end_sec = os::elapsedTime();
5701   double elapsed_ms = (end_sec - start_sec) * 1000.0;
5702 
5703   if (non_young) {
5704     non_young_time_ms += elapsed_ms;
5705   } else {
5706     young_time_ms += elapsed_ms;
5707   }
5708 
5709   prepend_to_freelist(&local_free_list);
5710   decrement_summary_bytes(pre_used);
5711   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5712   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5713 }
5714 
5715 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5716  private:
5717   FreeRegionList* _free_region_list;
5718   HeapRegionSet* _proxy_set;
5719   HeapRegionSetCount _humongous_regions_removed;
5720   size_t _freed_bytes;
5721  public:
5722 
5723   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5724     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5725   }
5726 
5727   virtual bool doHeapRegion(HeapRegion* r) {
5728     if (!r->is_starts_humongous()) {
5729       return false;
5730     }
5731 
5732     G1CollectedHeap* g1h = G1CollectedHeap::heap();
5733 
5734     oop obj = (oop)r->bottom();
5735     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5736 
5737     // The following checks whether the humongous object is live are sufficient.
5738     // The main additional check (in addition to having a reference from the roots
5739     // or the young gen) is whether the humongous object has a remembered set entry.
5740     //
5741     // A humongous object cannot be live if there is no remembered set for it
5742     // because:
5743     // - there can be no references from within humongous starts regions referencing
5744     // the object because we never allocate other objects into them.
5745     // (I.e. there are no intra-region references that may be missed by the
5746     // remembered set)
5747     // - as soon there is a remembered set entry to the humongous starts region
5748     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5749     // until the end of a concurrent mark.
5750     //
5751     // It is not required to check whether the object has been found dead by marking
5752     // or not, in fact it would prevent reclamation within a concurrent cycle, as
5753     // all objects allocated during that time are considered live.
5754     // SATB marking is even more conservative than the remembered set.
5755     // So if at this point in the collection there is no remembered set entry,
5756     // nobody has a reference to it.
5757     // At the start of collection we flush all refinement logs, and remembered sets
5758     // are completely up-to-date wrt to references to the humongous object.
5759     //
5760     // Other implementation considerations:
5761     // - never consider object arrays at this time because they would pose
5762     // considerable effort for cleaning up the the remembered sets. This is
5763     // required because stale remembered sets might reference locations that
5764     // are currently allocated into.
5765     uint region_idx = r->hrm_index();
5766     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5767         !r->rem_set()->is_empty()) {
5768 
5769       if (G1TraceEagerReclaimHumongousObjects) {
5770         gclog_or_tty->print_cr("Live humongous region %u size " SIZE_FORMAT " start " PTR_FORMAT " length %u with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
5771                                region_idx,
5772                                (size_t)obj->size() * HeapWordSize,
5773                                p2i(r->bottom()),
5774                                r->region_num(),
5775                                r->rem_set()->occupied(),
5776                                r->rem_set()->strong_code_roots_list_length(),
5777                                next_bitmap->isMarked(r->bottom()),
5778                                g1h->is_humongous_reclaim_candidate(region_idx),
5779                                obj->is_typeArray()
5780                               );
5781       }
5782 
5783       return false;
5784     }
5785 
5786     guarantee(obj->is_typeArray(),
5787               "Only eagerly reclaiming type arrays is supported, but the object "
5788               PTR_FORMAT " is not.", p2i(r->bottom()));
5789 
5790     if (G1TraceEagerReclaimHumongousObjects) {
5791       gclog_or_tty->print_cr("Dead humongous region %u size " SIZE_FORMAT " start " PTR_FORMAT " length %u with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
5792                              region_idx,
5793                              (size_t)obj->size() * HeapWordSize,
5794                              p2i(r->bottom()),
5795                              r->region_num(),
5796                              r->rem_set()->occupied(),
5797                              r->rem_set()->strong_code_roots_list_length(),
5798                              next_bitmap->isMarked(r->bottom()),
5799                              g1h->is_humongous_reclaim_candidate(region_idx),
5800                              obj->is_typeArray()
5801                             );
5802     }
5803     // Need to clear mark bit of the humongous object if already set.
5804     if (next_bitmap->isMarked(r->bottom())) {
5805       next_bitmap->clear(r->bottom());
5806     }
5807     _freed_bytes += r->used();
5808     r->set_containing_set(NULL);
5809     _humongous_regions_removed.increment(1u, r->capacity());
5810     g1h->free_humongous_region(r, _free_region_list, false);
5811 
5812     return false;
5813   }
5814 
5815   HeapRegionSetCount& humongous_free_count() {
5816     return _humongous_regions_removed;
5817   }
5818 
5819   size_t bytes_freed() const {
5820     return _freed_bytes;
5821   }
5822 
5823   size_t humongous_reclaimed() const {
5824     return _humongous_regions_removed.length();
5825   }
5826 };
5827 
5828 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5829   assert_at_safepoint(true);
5830 
5831   if (!G1EagerReclaimHumongousObjects ||
5832       (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5833     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5834     return;
5835   }
5836 
5837   double start_time = os::elapsedTime();
5838 
5839   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5840 
5841   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5842   heap_region_iterate(&cl);
5843 
5844   HeapRegionSetCount empty_set;
5845   remove_from_old_sets(empty_set, cl.humongous_free_count());
5846 
5847   G1HRPrinter* hrp = hr_printer();
5848   if (hrp->is_active()) {
5849     FreeRegionListIterator iter(&local_cleanup_list);
5850     while (iter.more_available()) {
5851       HeapRegion* hr = iter.get_next();
5852       hrp->cleanup(hr);
5853     }
5854   }
5855 
5856   prepend_to_freelist(&local_cleanup_list);
5857   decrement_summary_bytes(cl.bytes_freed());
5858 
5859   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5860                                                                     cl.humongous_reclaimed());
5861 }
5862 
5863 // This routine is similar to the above but does not record
5864 // any policy statistics or update free lists; we are abandoning
5865 // the current incremental collection set in preparation of a
5866 // full collection. After the full GC we will start to build up
5867 // the incremental collection set again.
5868 // This is only called when we're doing a full collection
5869 // and is immediately followed by the tearing down of the young list.
5870 
5871 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5872   HeapRegion* cur = cs_head;
5873 
5874   while (cur != NULL) {
5875     HeapRegion* next = cur->next_in_collection_set();
5876     assert(cur->in_collection_set(), "bad CS");
5877     cur->set_next_in_collection_set(NULL);
5878     clear_in_cset(cur);
5879     cur->set_young_index_in_cset(-1);
5880     cur = next;
5881   }
5882 }
5883 
5884 void G1CollectedHeap::set_free_regions_coming() {
5885   if (G1ConcRegionFreeingVerbose) {
5886     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5887                            "setting free regions coming");
5888   }
5889 
5890   assert(!free_regions_coming(), "pre-condition");
5891   _free_regions_coming = true;
5892 }
5893 
5894 void G1CollectedHeap::reset_free_regions_coming() {
5895   assert(free_regions_coming(), "pre-condition");
5896 
5897   {
5898     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5899     _free_regions_coming = false;
5900     SecondaryFreeList_lock->notify_all();
5901   }
5902 
5903   if (G1ConcRegionFreeingVerbose) {
5904     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5905                            "reset free regions coming");
5906   }
5907 }
5908 
5909 void G1CollectedHeap::wait_while_free_regions_coming() {
5910   // Most of the time we won't have to wait, so let's do a quick test
5911   // first before we take the lock.
5912   if (!free_regions_coming()) {
5913     return;
5914   }
5915 
5916   if (G1ConcRegionFreeingVerbose) {
5917     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5918                            "waiting for free regions");
5919   }
5920 
5921   {
5922     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5923     while (free_regions_coming()) {
5924       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5925     }
5926   }
5927 
5928   if (G1ConcRegionFreeingVerbose) {
5929     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5930                            "done waiting for free regions");
5931   }
5932 }
5933 
5934 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5935   return _allocator->is_retained_old_region(hr);
5936 }
5937 
5938 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5939   _young_list->push_region(hr);
5940 }
5941 
5942 class NoYoungRegionsClosure: public HeapRegionClosure {
5943 private:
5944   bool _success;
5945 public:
5946   NoYoungRegionsClosure() : _success(true) { }
5947   bool doHeapRegion(HeapRegion* r) {
5948     if (r->is_young()) {
5949       gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5950                              p2i(r->bottom()), p2i(r->end()));
5951       _success = false;
5952     }
5953     return false;
5954   }
5955   bool success() { return _success; }
5956 };
5957 
5958 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5959   bool ret = _young_list->check_list_empty(check_sample);
5960 
5961   if (check_heap) {
5962     NoYoungRegionsClosure closure;
5963     heap_region_iterate(&closure);
5964     ret = ret && closure.success();
5965   }
5966 
5967   return ret;
5968 }
5969 
5970 class TearDownRegionSetsClosure : public HeapRegionClosure {
5971 private:
5972   HeapRegionSet *_old_set;
5973 
5974 public:
5975   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5976 
5977   bool doHeapRegion(HeapRegion* r) {
5978     if (r->is_old()) {
5979       _old_set->remove(r);
5980     } else {
5981       // We ignore free regions, we'll empty the free list afterwards.
5982       // We ignore young regions, we'll empty the young list afterwards.
5983       // We ignore humongous regions, we're not tearing down the
5984       // humongous regions set.
5985       assert(r->is_free() || r->is_young() || r->is_humongous(),
5986              "it cannot be another type");
5987     }
5988     return false;
5989   }
5990 
5991   ~TearDownRegionSetsClosure() {
5992     assert(_old_set->is_empty(), "post-condition");
5993   }
5994 };
5995 
5996 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5997   assert_at_safepoint(true /* should_be_vm_thread */);
5998 
5999   if (!free_list_only) {
6000     TearDownRegionSetsClosure cl(&_old_set);
6001     heap_region_iterate(&cl);
6002 
6003     // Note that emptying the _young_list is postponed and instead done as
6004     // the first step when rebuilding the regions sets again. The reason for
6005     // this is that during a full GC string deduplication needs to know if
6006     // a collected region was young or old when the full GC was initiated.
6007   }
6008   _hrm.remove_all_free_regions();
6009 }
6010 
6011 void G1CollectedHeap::increase_used(size_t bytes) {
6012   _summary_bytes_used += bytes;
6013 }
6014 
6015 void G1CollectedHeap::decrease_used(size_t bytes) {
6016   assert(_summary_bytes_used >= bytes,
6017          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6018          _summary_bytes_used, bytes);
6019   _summary_bytes_used -= bytes;
6020 }
6021 
6022 void G1CollectedHeap::set_used(size_t bytes) {
6023   _summary_bytes_used = bytes;
6024 }
6025 
6026 class RebuildRegionSetsClosure : public HeapRegionClosure {
6027 private:
6028   bool            _free_list_only;
6029   HeapRegionSet*   _old_set;
6030   HeapRegionManager*   _hrm;
6031   size_t          _total_used;
6032 
6033 public:
6034   RebuildRegionSetsClosure(bool free_list_only,
6035                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
6036     _free_list_only(free_list_only),
6037     _old_set(old_set), _hrm(hrm), _total_used(0) {
6038     assert(_hrm->num_free_regions() == 0, "pre-condition");
6039     if (!free_list_only) {
6040       assert(_old_set->is_empty(), "pre-condition");
6041     }
6042   }
6043 
6044   bool doHeapRegion(HeapRegion* r) {
6045     if (r->is_continues_humongous()) {
6046       return false;
6047     }
6048 
6049     if (r->is_empty()) {
6050       // Add free regions to the free list
6051       r->set_free();
6052       r->set_allocation_context(AllocationContext::system());
6053       _hrm->insert_into_free_list(r);
6054     } else if (!_free_list_only) {
6055       assert(!r->is_young(), "we should not come across young regions");
6056 
6057       if (r->is_humongous()) {
6058         // We ignore humongous regions. We left the humongous set unchanged.
6059       } else {
6060         // Objects that were compacted would have ended up on regions
6061         // that were previously old or free.  Archive regions (which are
6062         // old) will not have been touched.
6063         assert(r->is_free() || r->is_old(), "invariant");
6064         // We now consider them old, so register as such. Leave
6065         // archive regions set that way, however, while still adding
6066         // them to the old set.
6067         if (!r->is_archive()) {
6068           r->set_old();
6069         }
6070         _old_set->add(r);
6071       }
6072       _total_used += r->used();
6073     }
6074 
6075     return false;
6076   }
6077 
6078   size_t total_used() {
6079     return _total_used;
6080   }
6081 };
6082 
6083 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6084   assert_at_safepoint(true /* should_be_vm_thread */);
6085 
6086   if (!free_list_only) {
6087     _young_list->empty_list();
6088   }
6089 
6090   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6091   heap_region_iterate(&cl);
6092 
6093   if (!free_list_only) {
6094     set_used(cl.total_used());
6095     if (_archive_allocator != NULL) {
6096       _archive_allocator->clear_used();
6097     }
6098   }
6099   assert(used_unlocked() == recalculate_used(),
6100          "inconsistent used_unlocked(), "
6101          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6102          used_unlocked(), recalculate_used());
6103 }
6104 
6105 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6106   _refine_cte_cl->set_concurrent(concurrent);
6107 }
6108 
6109 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6110   HeapRegion* hr = heap_region_containing(p);
6111   return hr->is_in(p);
6112 }
6113 
6114 // Methods for the mutator alloc region
6115 
6116 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6117                                                       bool force) {
6118   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6119   assert(!force || g1_policy()->can_expand_young_list(),
6120          "if force is true we should be able to expand the young list");
6121   bool young_list_full = g1_policy()->is_young_list_full();
6122   if (force || !young_list_full) {
6123     HeapRegion* new_alloc_region = new_region(word_size,
6124                                               false /* is_old */,
6125                                               false /* do_expand */);
6126     if (new_alloc_region != NULL) {
6127       set_region_short_lived_locked(new_alloc_region);
6128       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6129       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6130       return new_alloc_region;
6131     }
6132   }
6133   return NULL;
6134 }
6135 
6136 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6137                                                   size_t allocated_bytes) {
6138   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6139   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6140 
6141   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6142   increase_used(allocated_bytes);
6143   _hr_printer.retire(alloc_region);
6144   // We update the eden sizes here, when the region is retired,
6145   // instead of when it's allocated, since this is the point that its
6146   // used space has been recored in _summary_bytes_used.
6147   g1mm()->update_eden_size();
6148 }
6149 
6150 // Methods for the GC alloc regions
6151 
6152 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6153                                                  uint count,
6154                                                  InCSetState dest) {
6155   assert(FreeList_lock->owned_by_self(), "pre-condition");
6156 
6157   if (count < g1_policy()->max_regions(dest)) {
6158     const bool is_survivor = (dest.is_young());
6159     HeapRegion* new_alloc_region = new_region(word_size,
6160                                               !is_survivor,
6161                                               true /* do_expand */);
6162     if (new_alloc_region != NULL) {
6163       // We really only need to do this for old regions given that we
6164       // should never scan survivors. But it doesn't hurt to do it
6165       // for survivors too.
6166       new_alloc_region->record_timestamp();
6167       if (is_survivor) {
6168         new_alloc_region->set_survivor();
6169         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6170         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6171       } else {
6172         new_alloc_region->set_old();
6173         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6174         check_bitmaps("Old Region Allocation", new_alloc_region);
6175       }
6176       bool during_im = collector_state()->during_initial_mark_pause();
6177       new_alloc_region->note_start_of_copying(during_im);
6178       return new_alloc_region;
6179     }
6180   }
6181   return NULL;
6182 }
6183 
6184 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6185                                              size_t allocated_bytes,
6186                                              InCSetState dest) {
6187   bool during_im = collector_state()->during_initial_mark_pause();
6188   alloc_region->note_end_of_copying(during_im);
6189   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6190   if (dest.is_young()) {
6191     young_list()->add_survivor_region(alloc_region);
6192   } else {
6193     _old_set.add(alloc_region);
6194   }
6195   _hr_printer.retire(alloc_region);
6196 }
6197 
6198 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6199   bool expanded = false;
6200   uint index = _hrm.find_highest_free(&expanded);
6201 
6202   if (index != G1_NO_HRM_INDEX) {
6203     if (expanded) {
6204       ergo_verbose1(ErgoHeapSizing,
6205                     "attempt heap expansion",
6206                     ergo_format_reason("requested address range outside heap bounds")
6207                     ergo_format_byte("region size"),
6208                     HeapRegion::GrainWords * HeapWordSize);
6209     }
6210     _hrm.allocate_free_regions_starting_at(index, 1);
6211     return region_at(index);
6212   }
6213   return NULL;
6214 }
6215 
6216 // Heap region set verification
6217 
6218 class VerifyRegionListsClosure : public HeapRegionClosure {
6219 private:
6220   HeapRegionSet*   _old_set;
6221   HeapRegionSet*   _humongous_set;
6222   HeapRegionManager*   _hrm;
6223 
6224 public:
6225   HeapRegionSetCount _old_count;
6226   HeapRegionSetCount _humongous_count;
6227   HeapRegionSetCount _free_count;
6228 
6229   VerifyRegionListsClosure(HeapRegionSet* old_set,
6230                            HeapRegionSet* humongous_set,
6231                            HeapRegionManager* hrm) :
6232     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6233     _old_count(), _humongous_count(), _free_count(){ }
6234 
6235   bool doHeapRegion(HeapRegion* hr) {
6236     if (hr->is_continues_humongous()) {
6237       return false;
6238     }
6239 
6240     if (hr->is_young()) {
6241       // TODO
6242     } else if (hr->is_starts_humongous()) {
6243       assert(hr->containing_set() == _humongous_set, "Heap region %u is starts humongous but not in humongous set.", hr->hrm_index());
6244       _humongous_count.increment(1u, hr->capacity());
6245     } else if (hr->is_empty()) {
6246       assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6247       _free_count.increment(1u, hr->capacity());
6248     } else if (hr->is_old()) {
6249       assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6250       _old_count.increment(1u, hr->capacity());
6251     } else {
6252       // There are no other valid region types. Check for one invalid
6253       // one we can identify: pinned without old or humongous set.
6254       assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6255       ShouldNotReachHere();
6256     }
6257     return false;
6258   }
6259 
6260   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6261     guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6262     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6263               old_set->total_capacity_bytes(), _old_count.capacity());
6264 
6265     guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6266     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6267               humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6268 
6269     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());
6270     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6271               free_list->total_capacity_bytes(), _free_count.capacity());
6272   }
6273 };
6274 
6275 void G1CollectedHeap::verify_region_sets() {
6276   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6277 
6278   // First, check the explicit lists.
6279   _hrm.verify();
6280   {
6281     // Given that a concurrent operation might be adding regions to
6282     // the secondary free list we have to take the lock before
6283     // verifying it.
6284     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6285     _secondary_free_list.verify_list();
6286   }
6287 
6288   // If a concurrent region freeing operation is in progress it will
6289   // be difficult to correctly attributed any free regions we come
6290   // across to the correct free list given that they might belong to
6291   // one of several (free_list, secondary_free_list, any local lists,
6292   // etc.). So, if that's the case we will skip the rest of the
6293   // verification operation. Alternatively, waiting for the concurrent
6294   // operation to complete will have a non-trivial effect on the GC's
6295   // operation (no concurrent operation will last longer than the
6296   // interval between two calls to verification) and it might hide
6297   // any issues that we would like to catch during testing.
6298   if (free_regions_coming()) {
6299     return;
6300   }
6301 
6302   // Make sure we append the secondary_free_list on the free_list so
6303   // that all free regions we will come across can be safely
6304   // attributed to the free_list.
6305   append_secondary_free_list_if_not_empty_with_lock();
6306 
6307   // Finally, make sure that the region accounting in the lists is
6308   // consistent with what we see in the heap.
6309 
6310   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6311   heap_region_iterate(&cl);
6312   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6313 }
6314 
6315 // Optimized nmethod scanning
6316 
6317 class RegisterNMethodOopClosure: public OopClosure {
6318   G1CollectedHeap* _g1h;
6319   nmethod* _nm;
6320 
6321   template <class T> void do_oop_work(T* p) {
6322     T heap_oop = oopDesc::load_heap_oop(p);
6323     if (!oopDesc::is_null(heap_oop)) {
6324       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6325       HeapRegion* hr = _g1h->heap_region_containing(obj);
6326       assert(!hr->is_continues_humongous(),
6327              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6328              " starting at " HR_FORMAT,
6329              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6330 
6331       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6332       hr->add_strong_code_root_locked(_nm);
6333     }
6334   }
6335 
6336 public:
6337   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6338     _g1h(g1h), _nm(nm) {}
6339 
6340   void do_oop(oop* p)       { do_oop_work(p); }
6341   void do_oop(narrowOop* p) { do_oop_work(p); }
6342 };
6343 
6344 class UnregisterNMethodOopClosure: public OopClosure {
6345   G1CollectedHeap* _g1h;
6346   nmethod* _nm;
6347 
6348   template <class T> void do_oop_work(T* p) {
6349     T heap_oop = oopDesc::load_heap_oop(p);
6350     if (!oopDesc::is_null(heap_oop)) {
6351       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6352       HeapRegion* hr = _g1h->heap_region_containing(obj);
6353       assert(!hr->is_continues_humongous(),
6354              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6355              " starting at " HR_FORMAT,
6356              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6357 
6358       hr->remove_strong_code_root(_nm);
6359     }
6360   }
6361 
6362 public:
6363   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6364     _g1h(g1h), _nm(nm) {}
6365 
6366   void do_oop(oop* p)       { do_oop_work(p); }
6367   void do_oop(narrowOop* p) { do_oop_work(p); }
6368 };
6369 
6370 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6371   CollectedHeap::register_nmethod(nm);
6372 
6373   guarantee(nm != NULL, "sanity");
6374   RegisterNMethodOopClosure reg_cl(this, nm);
6375   nm->oops_do(&reg_cl);
6376 }
6377 
6378 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6379   CollectedHeap::unregister_nmethod(nm);
6380 
6381   guarantee(nm != NULL, "sanity");
6382   UnregisterNMethodOopClosure reg_cl(this, nm);
6383   nm->oops_do(&reg_cl, true);
6384 }
6385 
6386 void G1CollectedHeap::purge_code_root_memory() {
6387   double purge_start = os::elapsedTime();
6388   G1CodeRootSet::purge();
6389   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6390   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6391 }
6392 
6393 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6394   G1CollectedHeap* _g1h;
6395 
6396 public:
6397   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6398     _g1h(g1h) {}
6399 
6400   void do_code_blob(CodeBlob* cb) {
6401     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6402     if (nm == NULL) {
6403       return;
6404     }
6405 
6406     if (ScavengeRootsInCode) {
6407       _g1h->register_nmethod(nm);
6408     }
6409   }
6410 };
6411 
6412 void G1CollectedHeap::rebuild_strong_code_roots() {
6413   RebuildStrongCodeRootClosure blob_cl(this);
6414   CodeCache::blobs_do(&blob_cl);
6415 }
--- EOF ---