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       fill_with_non_humongous_objects(bottom_address, fill_size);
 891       increase_used(fill_size * HeapWordSize);
 892     }
 893   }
 894 }
 895 
 896 void G1CollectedHeap::fill_with_non_humongous_objects(HeapWord* start, size_t words, bool zap)
 897 {
 898   size_t prev_filler_array_max_size = _filler_array_max_size;
 899   _filler_array_max_size = _humongous_object_threshold_in_words;
 900 
 901   CollectedHeap::fill_with_objects(start, words);
 902 
 903   _filler_array_max_size = prev_filler_array_max_size;
 904 }
 905 
 906 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
 907                                                      uint* gc_count_before_ret,
 908                                                      uint* gclocker_retry_count_ret) {
 909   assert_heap_not_locked_and_not_at_safepoint();
 910   assert(!is_humongous(word_size), "attempt_allocation() should not "
 911          "be called for humongous allocation requests");
 912 
 913   AllocationContext_t context = AllocationContext::current();
 914   HeapWord* result = _allocator->attempt_allocation(word_size, context);
 915 
 916   if (result == NULL) {
 917     result = attempt_allocation_slow(word_size,
 918                                      context,
 919                                      gc_count_before_ret,
 920                                      gclocker_retry_count_ret);
 921   }
 922   assert_heap_not_locked();
 923   if (result != NULL) {
 924     dirty_young_block(result, word_size);
 925   }
 926   return result;
 927 }
 928 
 929 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 930   assert(!is_init_completed(), "Expect to be called at JVM init time");
 931   assert(ranges != NULL, "MemRegion array NULL");
 932   assert(count != 0, "No MemRegions provided");
 933   MemRegion reserved = _hrm.reserved();
 934   HeapWord* prev_last_addr = NULL;
 935   HeapRegion* prev_last_region = NULL;
 936   size_t size_used = 0;
 937   size_t uncommitted_regions = 0;
 938 
 939   // For each Memregion, free the G1 regions that constitute it, and
 940   // notify mark-sweep that the range is no longer to be considered 'archive.'
 941   MutexLockerEx x(Heap_lock);
 942   for (size_t i = 0; i < count; i++) {
 943     HeapWord* start_address = ranges[i].start();
 944     HeapWord* last_address = ranges[i].last();
 945 
 946     assert(reserved.contains(start_address) && reserved.contains(last_address),
 947            "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
 948            p2i(start_address), p2i(last_address));
 949     assert(start_address > prev_last_addr,
 950            "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
 951            p2i(start_address), p2i(prev_last_addr));
 952     size_used += ranges[i].byte_size();
 953     prev_last_addr = last_address;
 954 
 955     HeapRegion* start_region = _hrm.addr_to_region(start_address);
 956     HeapRegion* last_region = _hrm.addr_to_region(last_address);
 957 
 958     // Check for ranges that start in the same G1 region in which the previous
 959     // range ended, and adjust the start address so we don't try to free
 960     // the same region again. If the current range is entirely within that
 961     // region, skip it.
 962     if (start_region == prev_last_region) {
 963       start_address = start_region->end();
 964       if (start_address > last_address) {
 965         continue;
 966       }
 967       start_region = _hrm.addr_to_region(start_address);
 968     }
 969     prev_last_region = last_region;
 970 
 971     // After verifying that each region was marked as an archive region by
 972     // alloc_archive_regions, set it free and empty and uncommit it.
 973     HeapRegion* curr_region = start_region;
 974     while (curr_region != NULL) {
 975       guarantee(curr_region->is_archive(),
 976                 "Expected archive region at index %u", curr_region->hrm_index());
 977       uint curr_index = curr_region->hrm_index();
 978       _old_set.remove(curr_region);
 979       curr_region->set_free();
 980       curr_region->set_top(curr_region->bottom());
 981       if (curr_region != last_region) {
 982         curr_region = _hrm.next_region_in_heap(curr_region);
 983       } else {
 984         curr_region = NULL;
 985       }
 986       _hrm.shrink_at(curr_index, 1);
 987       uncommitted_regions++;
 988     }
 989 
 990     // Notify mark-sweep that this is no longer an archive range.
 991     G1MarkSweep::set_range_archive(ranges[i], false);
 992   }
 993 
 994   if (uncommitted_regions != 0) {
 995     ergo_verbose1(ErgoHeapSizing,
 996                   "attempt heap shrinking",
 997                   ergo_format_reason("uncommitted archive regions")
 998                   ergo_format_byte("total size"),
 999                   HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
1000   }
1001   decrease_used(size_used);
1002 }
1003 
1004 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1005                                                         uint* gc_count_before_ret,
1006                                                         uint* gclocker_retry_count_ret) {
1007   // The structure of this method has a lot of similarities to
1008   // attempt_allocation_slow(). The reason these two were not merged
1009   // into a single one is that such a method would require several "if
1010   // allocation is not humongous do this, otherwise do that"
1011   // conditional paths which would obscure its flow. In fact, an early
1012   // version of this code did use a unified method which was harder to
1013   // follow and, as a result, it had subtle bugs that were hard to
1014   // track down. So keeping these two methods separate allows each to
1015   // be more readable. It will be good to keep these two in sync as
1016   // much as possible.
1017 
1018   assert_heap_not_locked_and_not_at_safepoint();
1019   assert(is_humongous(word_size), "attempt_allocation_humongous() "
1020          "should only be called for humongous allocations");
1021 
1022   // Humongous objects can exhaust the heap quickly, so we should check if we
1023   // need to start a marking cycle at each humongous object allocation. We do
1024   // the check before we do the actual allocation. The reason for doing it
1025   // before the allocation is that we avoid having to keep track of the newly
1026   // allocated memory while we do a GC.
1027   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1028                                            word_size)) {
1029     collect(GCCause::_g1_humongous_allocation);
1030   }
1031 
1032   // We will loop until a) we manage to successfully perform the
1033   // allocation or b) we successfully schedule a collection which
1034   // fails to perform the allocation. b) is the only case when we'll
1035   // return NULL.
1036   HeapWord* result = NULL;
1037   for (int try_count = 1; /* we'll return */; try_count += 1) {
1038     bool should_try_gc;
1039     uint gc_count_before;
1040 
1041     {
1042       MutexLockerEx x(Heap_lock);
1043 
1044       // Given that humongous objects are not allocated in young
1045       // regions, we'll first try to do the allocation without doing a
1046       // collection hoping that there's enough space in the heap.
1047       result = humongous_obj_allocate(word_size, AllocationContext::current());
1048       if (result != NULL) {
1049         return result;
1050       }
1051 
1052       if (GC_locker::is_active_and_needs_gc()) {
1053         should_try_gc = false;
1054       } else {
1055          // The GCLocker may not be active but the GCLocker initiated
1056         // GC may not yet have been performed (GCLocker::needs_gc()
1057         // returns true). In this case we do not try this GC and
1058         // wait until the GCLocker initiated GC is performed, and
1059         // then retry the allocation.
1060         if (GC_locker::needs_gc()) {
1061           should_try_gc = false;
1062         } else {
1063           // Read the GC count while still holding the Heap_lock.
1064           gc_count_before = total_collections();
1065           should_try_gc = true;
1066         }
1067       }
1068     }
1069 
1070     if (should_try_gc) {
1071       // If we failed to allocate the humongous object, we should try to
1072       // do a collection pause (if we're allowed) in case it reclaims
1073       // enough space for the allocation to succeed after the pause.
1074 
1075       bool succeeded;
1076       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1077                                    GCCause::_g1_humongous_allocation);
1078       if (result != NULL) {
1079         assert(succeeded, "only way to get back a non-NULL result");
1080         return result;
1081       }
1082 
1083       if (succeeded) {
1084         // If we get here we successfully scheduled a collection which
1085         // failed to allocate. No point in trying to allocate
1086         // further. We'll just return NULL.
1087         MutexLockerEx x(Heap_lock);
1088         *gc_count_before_ret = total_collections();
1089         return NULL;
1090       }
1091     } else {
1092       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1093         MutexLockerEx x(Heap_lock);
1094         *gc_count_before_ret = total_collections();
1095         return NULL;
1096       }
1097       // The GCLocker is either active or the GCLocker initiated
1098       // GC has not yet been performed. Stall until it is and
1099       // then retry the allocation.
1100       GC_locker::stall_until_clear();
1101       (*gclocker_retry_count_ret) += 1;
1102     }
1103 
1104     // We can reach here if we were unsuccessful in scheduling a
1105     // collection (because another thread beat us to it) or if we were
1106     // stalled due to the GC locker. In either can we should retry the
1107     // allocation attempt in case another thread successfully
1108     // performed a collection and reclaimed enough space.  Give a
1109     // warning if we seem to be looping forever.
1110 
1111     if ((QueuedAllocationWarningCount > 0) &&
1112         (try_count % QueuedAllocationWarningCount == 0)) {
1113       warning("G1CollectedHeap::attempt_allocation_humongous() "
1114               "retries %d times", try_count);
1115     }
1116   }
1117 
1118   ShouldNotReachHere();
1119   return NULL;
1120 }
1121 
1122 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1123                                                            AllocationContext_t context,
1124                                                            bool expect_null_mutator_alloc_region) {
1125   assert_at_safepoint(true /* should_be_vm_thread */);
1126   assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1127          "the current alloc region was unexpectedly found to be non-NULL");
1128 
1129   if (!is_humongous(word_size)) {
1130     return _allocator->attempt_allocation_locked(word_size, context);
1131   } else {
1132     HeapWord* result = humongous_obj_allocate(word_size, context);
1133     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1134       collector_state()->set_initiate_conc_mark_if_possible(true);
1135     }
1136     return result;
1137   }
1138 
1139   ShouldNotReachHere();
1140 }
1141 
1142 class PostMCRemSetClearClosure: public HeapRegionClosure {
1143   G1CollectedHeap* _g1h;
1144   ModRefBarrierSet* _mr_bs;
1145 public:
1146   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1147     _g1h(g1h), _mr_bs(mr_bs) {}
1148 
1149   bool doHeapRegion(HeapRegion* r) {
1150     HeapRegionRemSet* hrrs = r->rem_set();
1151 
1152     if (r->is_continues_humongous()) {
1153       // We'll assert that the strong code root list and RSet is empty
1154       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1155       assert(hrrs->occupied() == 0, "RSet should be empty");
1156       return false;
1157     }
1158 
1159     _g1h->reset_gc_time_stamps(r);
1160     hrrs->clear();
1161     // You might think here that we could clear just the cards
1162     // corresponding to the used region.  But no: if we leave a dirty card
1163     // in a region we might allocate into, then it would prevent that card
1164     // from being enqueued, and cause it to be missed.
1165     // Re: the performance cost: we shouldn't be doing full GC anyway!
1166     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1167 
1168     return false;
1169   }
1170 };
1171 
1172 void G1CollectedHeap::clear_rsets_post_compaction() {
1173   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1174   heap_region_iterate(&rs_clear);
1175 }
1176 
1177 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1178   G1CollectedHeap*   _g1h;
1179   UpdateRSOopClosure _cl;
1180 public:
1181   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1182     _cl(g1->g1_rem_set(), worker_i),
1183     _g1h(g1)
1184   { }
1185 
1186   bool doHeapRegion(HeapRegion* r) {
1187     if (!r->is_continues_humongous()) {
1188       _cl.set_from(r);
1189       r->oop_iterate(&_cl);
1190     }
1191     return false;
1192   }
1193 };
1194 
1195 class ParRebuildRSTask: public AbstractGangTask {
1196   G1CollectedHeap* _g1;
1197   HeapRegionClaimer _hrclaimer;
1198 
1199 public:
1200   ParRebuildRSTask(G1CollectedHeap* g1) :
1201       AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1202 
1203   void work(uint worker_id) {
1204     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1205     _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1206   }
1207 };
1208 
1209 class PostCompactionPrinterClosure: public HeapRegionClosure {
1210 private:
1211   G1HRPrinter* _hr_printer;
1212 public:
1213   bool doHeapRegion(HeapRegion* hr) {
1214     assert(!hr->is_young(), "not expecting to find young regions");
1215     if (hr->is_free()) {
1216       // We only generate output for non-empty regions.
1217     } else if (hr->is_starts_humongous()) {
1218       if (hr->region_num() == 1) {
1219         // single humongous region
1220         _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1221       } else {
1222         _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1223       }
1224     } else if (hr->is_continues_humongous()) {
1225       _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1226     } else if (hr->is_archive()) {
1227       _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1228     } else if (hr->is_old()) {
1229       _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1230     } else {
1231       ShouldNotReachHere();
1232     }
1233     return false;
1234   }
1235 
1236   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1237     : _hr_printer(hr_printer) { }
1238 };
1239 
1240 void G1CollectedHeap::print_hrm_post_compaction() {
1241   PostCompactionPrinterClosure cl(hr_printer());
1242   heap_region_iterate(&cl);
1243 }
1244 
1245 bool G1CollectedHeap::do_collection(bool explicit_gc,
1246                                     bool clear_all_soft_refs,
1247                                     size_t word_size) {
1248   assert_at_safepoint(true /* should_be_vm_thread */);
1249 
1250   if (GC_locker::check_active_before_gc()) {
1251     return false;
1252   }
1253 
1254   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1255   gc_timer->register_gc_start();
1256 
1257   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1258   GCIdMark gc_id_mark;
1259   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1260 
1261   SvcGCMarker sgcm(SvcGCMarker::FULL);
1262   ResourceMark rm;
1263 
1264   G1Log::update_level();
1265   print_heap_before_gc();
1266   trace_heap_before_gc(gc_tracer);
1267 
1268   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1269 
1270   verify_region_sets_optional();
1271 
1272   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1273                            collector_policy()->should_clear_all_soft_refs();
1274 
1275   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1276 
1277   {
1278     IsGCActiveMark x;
1279 
1280     // Timing
1281     assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1282     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1283 
1284     {
1285       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1286       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1287       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1288 
1289       g1_policy()->record_full_collection_start();
1290 
1291       // Note: When we have a more flexible GC logging framework that
1292       // allows us to add optional attributes to a GC log record we
1293       // could consider timing and reporting how long we wait in the
1294       // following two methods.
1295       wait_while_free_regions_coming();
1296       // If we start the compaction before the CM threads finish
1297       // scanning the root regions we might trip them over as we'll
1298       // be moving objects / updating references. So let's wait until
1299       // they are done. By telling them to abort, they should complete
1300       // early.
1301       _cm->root_regions()->abort();
1302       _cm->root_regions()->wait_until_scan_finished();
1303       append_secondary_free_list_if_not_empty_with_lock();
1304 
1305       gc_prologue(true);
1306       increment_total_collections(true /* full gc */);
1307       increment_old_marking_cycles_started();
1308 
1309       assert(used() == recalculate_used(), "Should be equal");
1310 
1311       verify_before_gc();
1312 
1313       check_bitmaps("Full GC Start");
1314       pre_full_gc_dump(gc_timer);
1315 
1316 #if defined(COMPILER2) || INCLUDE_JVMCI
1317       DerivedPointerTable::clear();
1318 #endif
1319 
1320       // Disable discovery and empty the discovered lists
1321       // for the CM ref processor.
1322       ref_processor_cm()->disable_discovery();
1323       ref_processor_cm()->abandon_partial_discovery();
1324       ref_processor_cm()->verify_no_references_recorded();
1325 
1326       // Abandon current iterations of concurrent marking and concurrent
1327       // refinement, if any are in progress. We have to do this before
1328       // wait_until_scan_finished() below.
1329       concurrent_mark()->abort();
1330 
1331       // Make sure we'll choose a new allocation region afterwards.
1332       _allocator->release_mutator_alloc_region();
1333       _allocator->abandon_gc_alloc_regions();
1334       g1_rem_set()->cleanupHRRS();
1335 
1336       // We should call this after we retire any currently active alloc
1337       // regions so that all the ALLOC / RETIRE events are generated
1338       // before the start GC event.
1339       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1340 
1341       // We may have added regions to the current incremental collection
1342       // set between the last GC or pause and now. We need to clear the
1343       // incremental collection set and then start rebuilding it afresh
1344       // after this full GC.
1345       abandon_collection_set(g1_policy()->inc_cset_head());
1346       g1_policy()->clear_incremental_cset();
1347       g1_policy()->stop_incremental_cset_building();
1348 
1349       tear_down_region_sets(false /* free_list_only */);
1350       collector_state()->set_gcs_are_young(true);
1351 
1352       // See the comments in g1CollectedHeap.hpp and
1353       // G1CollectedHeap::ref_processing_init() about
1354       // how reference processing currently works in G1.
1355 
1356       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1357       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1358 
1359       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1360       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1361 
1362       ref_processor_stw()->enable_discovery();
1363       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1364 
1365       // Do collection work
1366       {
1367         HandleMark hm;  // Discard invalid handles created during gc
1368         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1369       }
1370 
1371       assert(num_free_regions() == 0, "we should not have added any free regions");
1372       rebuild_region_sets(false /* free_list_only */);
1373 
1374       // Enqueue any discovered reference objects that have
1375       // not been removed from the discovered lists.
1376       ref_processor_stw()->enqueue_discovered_references();
1377 
1378 #if defined(COMPILER2) || INCLUDE_JVMCI
1379       DerivedPointerTable::update_pointers();
1380 #endif
1381 
1382       MemoryService::track_memory_usage();
1383 
1384       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1385       ref_processor_stw()->verify_no_references_recorded();
1386 
1387       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1388       ClassLoaderDataGraph::purge();
1389       MetaspaceAux::verify_metrics();
1390 
1391       // Note: since we've just done a full GC, concurrent
1392       // marking is no longer active. Therefore we need not
1393       // re-enable reference discovery for the CM ref processor.
1394       // That will be done at the start of the next marking cycle.
1395       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1396       ref_processor_cm()->verify_no_references_recorded();
1397 
1398       reset_gc_time_stamp();
1399       // Since everything potentially moved, we will clear all remembered
1400       // sets, and clear all cards.  Later we will rebuild remembered
1401       // sets. We will also reset the GC time stamps of the regions.
1402       clear_rsets_post_compaction();
1403       check_gc_time_stamps();
1404 
1405       // Resize the heap if necessary.
1406       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1407 
1408       if (_hr_printer.is_active()) {
1409         // We should do this after we potentially resize the heap so
1410         // that all the COMMIT / UNCOMMIT events are generated before
1411         // the end GC event.
1412 
1413         print_hrm_post_compaction();
1414         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1415       }
1416 
1417       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1418       if (hot_card_cache->use_cache()) {
1419         hot_card_cache->reset_card_counts();
1420         hot_card_cache->reset_hot_cache();
1421       }
1422 
1423       // Rebuild remembered sets of all regions.
1424       uint n_workers =
1425         AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1426                                                 workers()->active_workers(),
1427                                                 Threads::number_of_non_daemon_threads());
1428       workers()->set_active_workers(n_workers);
1429 
1430       ParRebuildRSTask rebuild_rs_task(this);
1431       workers()->run_task(&rebuild_rs_task);
1432 
1433       // Rebuild the strong code root lists for each region
1434       rebuild_strong_code_roots();
1435 
1436       if (true) { // FIXME
1437         MetaspaceGC::compute_new_size();
1438       }
1439 
1440 #ifdef TRACESPINNING
1441       ParallelTaskTerminator::print_termination_counts();
1442 #endif
1443 
1444       // Discard all rset updates
1445       JavaThread::dirty_card_queue_set().abandon_logs();
1446       assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1447 
1448       _young_list->reset_sampled_info();
1449       // At this point there should be no regions in the
1450       // entire heap tagged as young.
1451       assert(check_young_list_empty(true /* check_heap */),
1452              "young list should be empty at this point");
1453 
1454       // Update the number of full collections that have been completed.
1455       increment_old_marking_cycles_completed(false /* concurrent */);
1456 
1457       _hrm.verify_optional();
1458       verify_region_sets_optional();
1459 
1460       verify_after_gc();
1461 
1462       // Clear the previous marking bitmap, if needed for bitmap verification.
1463       // Note we cannot do this when we clear the next marking bitmap in
1464       // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1465       // objects marked during a full GC against the previous bitmap.
1466       // But we need to clear it before calling check_bitmaps below since
1467       // the full GC has compacted objects and updated TAMS but not updated
1468       // the prev bitmap.
1469       if (G1VerifyBitmaps) {
1470         ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1471       }
1472       check_bitmaps("Full GC End");
1473 
1474       // Start a new incremental collection set for the next pause
1475       assert(g1_policy()->collection_set() == NULL, "must be");
1476       g1_policy()->start_incremental_cset_building();
1477 
1478       clear_cset_fast_test();
1479 
1480       _allocator->init_mutator_alloc_region();
1481 
1482       g1_policy()->record_full_collection_end();
1483 
1484       if (G1Log::fine()) {
1485         g1_policy()->print_heap_transition();
1486       }
1487 
1488       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1489       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1490       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1491       // before any GC notifications are raised.
1492       g1mm()->update_sizes();
1493 
1494       gc_epilogue(true);
1495     }
1496 
1497     if (G1Log::finer()) {
1498       g1_policy()->print_detailed_heap_transition(true /* full */);
1499     }
1500 
1501     print_heap_after_gc();
1502     trace_heap_after_gc(gc_tracer);
1503 
1504     post_full_gc_dump(gc_timer);
1505 
1506     gc_timer->register_gc_end();
1507     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1508   }
1509 
1510   return true;
1511 }
1512 
1513 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1514   // do_collection() will return whether it succeeded in performing
1515   // the GC. Currently, there is no facility on the
1516   // do_full_collection() API to notify the caller than the collection
1517   // did not succeed (e.g., because it was locked out by the GC
1518   // locker). So, right now, we'll ignore the return value.
1519   bool dummy = do_collection(true,                /* explicit_gc */
1520                              clear_all_soft_refs,
1521                              0                    /* word_size */);
1522 }
1523 
1524 // This code is mostly copied from TenuredGeneration.
1525 void
1526 G1CollectedHeap::
1527 resize_if_necessary_after_full_collection(size_t word_size) {
1528   // Include the current allocation, if any, and bytes that will be
1529   // pre-allocated to support collections, as "used".
1530   const size_t used_after_gc = used();
1531   const size_t capacity_after_gc = capacity();
1532   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1533 
1534   // This is enforced in arguments.cpp.
1535   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1536          "otherwise the code below doesn't make sense");
1537 
1538   // We don't have floating point command-line arguments
1539   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1540   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1541   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1542   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1543 
1544   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1545   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1546 
1547   // We have to be careful here as these two calculations can overflow
1548   // 32-bit size_t's.
1549   double used_after_gc_d = (double) used_after_gc;
1550   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1551   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1552 
1553   // Let's make sure that they are both under the max heap size, which
1554   // by default will make them fit into a size_t.
1555   double desired_capacity_upper_bound = (double) max_heap_size;
1556   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1557                                     desired_capacity_upper_bound);
1558   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1559                                     desired_capacity_upper_bound);
1560 
1561   // We can now safely turn them into size_t's.
1562   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1563   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1564 
1565   // This assert only makes sense here, before we adjust them
1566   // with respect to the min and max heap size.
1567   assert(minimum_desired_capacity <= maximum_desired_capacity,
1568          "minimum_desired_capacity = " SIZE_FORMAT ", "
1569          "maximum_desired_capacity = " SIZE_FORMAT,
1570          minimum_desired_capacity, maximum_desired_capacity);
1571 
1572   // Should not be greater than the heap max size. No need to adjust
1573   // it with respect to the heap min size as it's a lower bound (i.e.,
1574   // we'll try to make the capacity larger than it, not smaller).
1575   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1576   // Should not be less than the heap min size. No need to adjust it
1577   // with respect to the heap max size as it's an upper bound (i.e.,
1578   // we'll try to make the capacity smaller than it, not greater).
1579   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1580 
1581   if (capacity_after_gc < minimum_desired_capacity) {
1582     // Don't expand unless it's significant
1583     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1584     ergo_verbose4(ErgoHeapSizing,
1585                   "attempt heap expansion",
1586                   ergo_format_reason("capacity lower than "
1587                                      "min desired capacity after Full GC")
1588                   ergo_format_byte("capacity")
1589                   ergo_format_byte("occupancy")
1590                   ergo_format_byte_perc("min desired capacity"),
1591                   capacity_after_gc, used_after_gc,
1592                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1593     expand(expand_bytes);
1594 
1595     // No expansion, now see if we want to shrink
1596   } else if (capacity_after_gc > maximum_desired_capacity) {
1597     // Capacity too large, compute shrinking size
1598     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1599     ergo_verbose4(ErgoHeapSizing,
1600                   "attempt heap shrinking",
1601                   ergo_format_reason("capacity higher than "
1602                                      "max desired capacity after Full GC")
1603                   ergo_format_byte("capacity")
1604                   ergo_format_byte("occupancy")
1605                   ergo_format_byte_perc("max desired capacity"),
1606                   capacity_after_gc, used_after_gc,
1607                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1608     shrink(shrink_bytes);
1609   }
1610 }
1611 
1612 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1613                                                             AllocationContext_t context,
1614                                                             bool do_gc,
1615                                                             bool clear_all_soft_refs,
1616                                                             bool expect_null_mutator_alloc_region,
1617                                                             bool* gc_succeeded) {
1618   *gc_succeeded = true;
1619   // Let's attempt the allocation first.
1620   HeapWord* result =
1621     attempt_allocation_at_safepoint(word_size,
1622                                     context,
1623                                     expect_null_mutator_alloc_region);
1624   if (result != NULL) {
1625     assert(*gc_succeeded, "sanity");
1626     return result;
1627   }
1628 
1629   // In a G1 heap, we're supposed to keep allocation from failing by
1630   // incremental pauses.  Therefore, at least for now, we'll favor
1631   // expansion over collection.  (This might change in the future if we can
1632   // do something smarter than full collection to satisfy a failed alloc.)
1633   result = expand_and_allocate(word_size, context);
1634   if (result != NULL) {
1635     assert(*gc_succeeded, "sanity");
1636     return result;
1637   }
1638 
1639   if (do_gc) {
1640     // Expansion didn't work, we'll try to do a Full GC.
1641     *gc_succeeded = do_collection(false, /* explicit_gc */
1642                                   clear_all_soft_refs,
1643                                   word_size);
1644   }
1645 
1646   return NULL;
1647 }
1648 
1649 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1650                                                      AllocationContext_t context,
1651                                                      bool* succeeded) {
1652   assert_at_safepoint(true /* should_be_vm_thread */);
1653 
1654   // Attempts to allocate followed by Full GC.
1655   HeapWord* result =
1656     satisfy_failed_allocation_helper(word_size,
1657                                      context,
1658                                      true,  /* do_gc */
1659                                      false, /* clear_all_soft_refs */
1660                                      false, /* expect_null_mutator_alloc_region */
1661                                      succeeded);
1662 
1663   if (result != NULL || !*succeeded) {
1664     return result;
1665   }
1666 
1667   // Attempts to allocate followed by Full GC that will collect all soft references.
1668   result = satisfy_failed_allocation_helper(word_size,
1669                                             context,
1670                                             true, /* do_gc */
1671                                             true, /* clear_all_soft_refs */
1672                                             true, /* expect_null_mutator_alloc_region */
1673                                             succeeded);
1674 
1675   if (result != NULL || !*succeeded) {
1676     return result;
1677   }
1678 
1679   // Attempts to allocate, no GC
1680   result = satisfy_failed_allocation_helper(word_size,
1681                                             context,
1682                                             false, /* do_gc */
1683                                             false, /* clear_all_soft_refs */
1684                                             true,  /* expect_null_mutator_alloc_region */
1685                                             succeeded);
1686 
1687   if (result != NULL) {
1688     assert(*succeeded, "sanity");
1689     return result;
1690   }
1691 
1692   assert(!collector_policy()->should_clear_all_soft_refs(),
1693          "Flag should have been handled and cleared prior to this point");
1694 
1695   // What else?  We might try synchronous finalization later.  If the total
1696   // space available is large enough for the allocation, then a more
1697   // complete compaction phase than we've tried so far might be
1698   // appropriate.
1699   assert(*succeeded, "sanity");
1700   return NULL;
1701 }
1702 
1703 // Attempting to expand the heap sufficiently
1704 // to support an allocation of the given "word_size".  If
1705 // successful, perform the allocation and return the address of the
1706 // allocated block, or else "NULL".
1707 
1708 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1709   assert_at_safepoint(true /* should_be_vm_thread */);
1710 
1711   verify_region_sets_optional();
1712 
1713   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1714   ergo_verbose1(ErgoHeapSizing,
1715                 "attempt heap expansion",
1716                 ergo_format_reason("allocation request failed")
1717                 ergo_format_byte("allocation request"),
1718                 word_size * HeapWordSize);
1719   if (expand(expand_bytes)) {
1720     _hrm.verify_optional();
1721     verify_region_sets_optional();
1722     return attempt_allocation_at_safepoint(word_size,
1723                                            context,
1724                                            false /* expect_null_mutator_alloc_region */);
1725   }
1726   return NULL;
1727 }
1728 
1729 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1730   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1731   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1732                                        HeapRegion::GrainBytes);
1733   ergo_verbose2(ErgoHeapSizing,
1734                 "expand the heap",
1735                 ergo_format_byte("requested expansion amount")
1736                 ergo_format_byte("attempted expansion amount"),
1737                 expand_bytes, aligned_expand_bytes);
1738 
1739   if (is_maximal_no_gc()) {
1740     ergo_verbose0(ErgoHeapSizing,
1741                       "did not expand the heap",
1742                       ergo_format_reason("heap already fully expanded"));
1743     return false;
1744   }
1745 
1746   double expand_heap_start_time_sec = os::elapsedTime();
1747   uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1748   assert(regions_to_expand > 0, "Must expand by at least one region");
1749 
1750   uint expanded_by = _hrm.expand_by(regions_to_expand);
1751   if (expand_time_ms != NULL) {
1752     *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1753   }
1754 
1755   if (expanded_by > 0) {
1756     size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1757     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1758     g1_policy()->record_new_heap_size(num_regions());
1759   } else {
1760     ergo_verbose0(ErgoHeapSizing,
1761                   "did not expand the heap",
1762                   ergo_format_reason("heap expansion operation failed"));
1763     // The expansion of the virtual storage space was unsuccessful.
1764     // Let's see if it was because we ran out of swap.
1765     if (G1ExitOnExpansionFailure &&
1766         _hrm.available() >= regions_to_expand) {
1767       // We had head room...
1768       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1769     }
1770   }
1771   return regions_to_expand > 0;
1772 }
1773 
1774 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1775   size_t aligned_shrink_bytes =
1776     ReservedSpace::page_align_size_down(shrink_bytes);
1777   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1778                                          HeapRegion::GrainBytes);
1779   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1780 
1781   uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1782   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1783 
1784   ergo_verbose3(ErgoHeapSizing,
1785                 "shrink the heap",
1786                 ergo_format_byte("requested shrinking amount")
1787                 ergo_format_byte("aligned shrinking amount")
1788                 ergo_format_byte("attempted shrinking amount"),
1789                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1790   if (num_regions_removed > 0) {
1791     g1_policy()->record_new_heap_size(num_regions());
1792   } else {
1793     ergo_verbose0(ErgoHeapSizing,
1794                   "did not shrink the heap",
1795                   ergo_format_reason("heap shrinking operation failed"));
1796   }
1797 }
1798 
1799 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1800   verify_region_sets_optional();
1801 
1802   // We should only reach here at the end of a Full GC which means we
1803   // should not not be holding to any GC alloc regions. The method
1804   // below will make sure of that and do any remaining clean up.
1805   _allocator->abandon_gc_alloc_regions();
1806 
1807   // Instead of tearing down / rebuilding the free lists here, we
1808   // could instead use the remove_all_pending() method on free_list to
1809   // remove only the ones that we need to remove.
1810   tear_down_region_sets(true /* free_list_only */);
1811   shrink_helper(shrink_bytes);
1812   rebuild_region_sets(true /* free_list_only */);
1813 
1814   _hrm.verify_optional();
1815   verify_region_sets_optional();
1816 }
1817 
1818 // Public methods.
1819 
1820 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1821   CollectedHeap(),
1822   _g1_policy(policy_),
1823   _dirty_card_queue_set(false),
1824   _into_cset_dirty_card_queue_set(false),
1825   _is_alive_closure_cm(this),
1826   _is_alive_closure_stw(this),
1827   _ref_processor_cm(NULL),
1828   _ref_processor_stw(NULL),
1829   _bot_shared(NULL),
1830   _cg1r(NULL),
1831   _g1mm(NULL),
1832   _refine_cte_cl(NULL),
1833   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1834   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1835   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1836   _humongous_reclaim_candidates(),
1837   _has_humongous_reclaim_candidates(false),
1838   _archive_allocator(NULL),
1839   _free_regions_coming(false),
1840   _young_list(new YoungList(this)),
1841   _gc_time_stamp(0),
1842   _summary_bytes_used(0),
1843   _survivor_evac_stats(YoungPLABSize, PLABWeight),
1844   _old_evac_stats(OldPLABSize, PLABWeight),
1845   _expand_heap_after_alloc_failure(true),
1846   _old_marking_cycles_started(0),
1847   _old_marking_cycles_completed(0),
1848   _heap_summary_sent(false),
1849   _in_cset_fast_test(),
1850   _dirty_cards_region_list(NULL),
1851   _worker_cset_start_region(NULL),
1852   _worker_cset_start_region_time_stamp(NULL),
1853   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1854   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1855   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1856   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1857 
1858   _workers = new WorkGang("GC Thread", ParallelGCThreads,
1859                           /* are_GC_task_threads */true,
1860                           /* are_ConcurrentGC_threads */false);
1861   _workers->initialize_workers();
1862 
1863   _allocator = G1Allocator::create_allocator(this);
1864   _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);




1865 
1866   uint n_queues = ParallelGCThreads;
1867   _task_queues = new RefToScanQueueSet(n_queues);
1868 
1869   uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1870   assert(n_rem_sets > 0, "Invariant.");
1871 
1872   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1873   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1874   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1875 
1876   for (uint i = 0; i < n_queues; i++) {
1877     RefToScanQueue* q = new RefToScanQueue();
1878     q->initialize();
1879     _task_queues->register_queue(i, q);
1880     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1881   }
1882   clear_cset_start_regions();
1883 
1884   // Initialize the G1EvacuationFailureALot counters and flags.
1885   NOT_PRODUCT(reset_evacuation_should_fail();)
1886 
1887   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1888 }
1889 
1890 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1891                                                                  size_t size,
1892                                                                  size_t translation_factor) {
1893   size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1894   // Allocate a new reserved space, preferring to use large pages.
1895   ReservedSpace rs(size, preferred_page_size);
1896   G1RegionToSpaceMapper* result  =
1897     G1RegionToSpaceMapper::create_mapper(rs,
1898                                          size,
1899                                          rs.alignment(),
1900                                          HeapRegion::GrainBytes,
1901                                          translation_factor,
1902                                          mtGC);
1903   if (TracePageSizes) {
1904     gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1905                            description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1906   }
1907   return result;
1908 }
1909 
1910 jint G1CollectedHeap::initialize() {
1911   CollectedHeap::pre_initialize();
1912   os::enable_vtime();
1913 
1914   G1Log::init();
1915 
1916   // Necessary to satisfy locking discipline assertions.
1917 
1918   MutexLocker x(Heap_lock);
1919 
1920   // We have to initialize the printer before committing the heap, as
1921   // it will be used then.
1922   _hr_printer.set_active(G1PrintHeapRegions);
1923 
1924   // While there are no constraints in the GC code that HeapWordSize
1925   // be any particular value, there are multiple other areas in the
1926   // system which believe this to be true (e.g. oop->object_size in some
1927   // cases incorrectly returns the size in wordSize units rather than
1928   // HeapWordSize).
1929   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1930 
1931   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1932   size_t max_byte_size = collector_policy()->max_heap_byte_size();
1933   size_t heap_alignment = collector_policy()->heap_alignment();
1934 
1935   // Ensure that the sizes are properly aligned.
1936   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1937   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1938   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1939 
1940   _refine_cte_cl = new RefineCardTableEntryClosure();
1941 
1942   jint ecode = JNI_OK;
1943   _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1944   if (_cg1r == NULL) {
1945     return ecode;
1946   }
1947 
1948   // Reserve the maximum.
1949 
1950   // When compressed oops are enabled, the preferred heap base
1951   // is calculated by subtracting the requested size from the
1952   // 32Gb boundary and using the result as the base address for
1953   // heap reservation. If the requested size is not aligned to
1954   // HeapRegion::GrainBytes (i.e. the alignment that is passed
1955   // into the ReservedHeapSpace constructor) then the actual
1956   // base of the reserved heap may end up differing from the
1957   // address that was requested (i.e. the preferred heap base).
1958   // If this happens then we could end up using a non-optimal
1959   // compressed oops mode.
1960 
1961   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1962                                                  heap_alignment);
1963 
1964   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1965 
1966   // Create the barrier set for the entire reserved region.
1967   G1SATBCardTableLoggingModRefBS* bs
1968     = new G1SATBCardTableLoggingModRefBS(reserved_region());
1969   bs->initialize();
1970   assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1971   set_barrier_set(bs);
1972 
1973   // Also create a G1 rem set.
1974   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1975 
1976   // Carve out the G1 part of the heap.
1977 
1978   ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1979   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1980   G1RegionToSpaceMapper* heap_storage =
1981     G1RegionToSpaceMapper::create_mapper(g1_rs,
1982                                          g1_rs.size(),
1983                                          page_size,
1984                                          HeapRegion::GrainBytes,
1985                                          1,
1986                                          mtJavaHeap);
1987   os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1988                        max_byte_size, page_size,
1989                        heap_rs.base(),
1990                        heap_rs.size());
1991   heap_storage->set_mapping_changed_listener(&_listener);
1992 
1993   // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1994   G1RegionToSpaceMapper* bot_storage =
1995     create_aux_memory_mapper("Block offset table",
1996                              G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1997                              G1BlockOffsetSharedArray::heap_map_factor());
1998 
1999   ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2000   G1RegionToSpaceMapper* cardtable_storage =
2001     create_aux_memory_mapper("Card table",
2002                              G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2003                              G1SATBCardTableLoggingModRefBS::heap_map_factor());
2004 
2005   G1RegionToSpaceMapper* card_counts_storage =
2006     create_aux_memory_mapper("Card counts table",
2007                              G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2008                              G1CardCounts::heap_map_factor());
2009 
2010   size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2011   G1RegionToSpaceMapper* prev_bitmap_storage =
2012     create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2013   G1RegionToSpaceMapper* next_bitmap_storage =
2014     create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2015 
2016   _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2017   g1_barrier_set()->initialize(cardtable_storage);
2018    // Do later initialization work for concurrent refinement.
2019   _cg1r->init(card_counts_storage);
2020 
2021   // 6843694 - ensure that the maximum region index can fit
2022   // in the remembered set structures.
2023   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2024   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2025 
2026   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2027   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2028   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2029             "too many cards per region");
2030 
2031   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2032 
2033   _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2034 
2035   {
2036     HeapWord* start = _hrm.reserved().start();
2037     HeapWord* end = _hrm.reserved().end();
2038     size_t granularity = HeapRegion::GrainBytes;
2039 
2040     _in_cset_fast_test.initialize(start, end, granularity);
2041     _humongous_reclaim_candidates.initialize(start, end, granularity);
2042   }
2043 
2044   // Create the ConcurrentMark data structure and thread.
2045   // (Must do this late, so that "max_regions" is defined.)
2046   _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2047   if (_cm == NULL || !_cm->completed_initialization()) {
2048     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2049     return JNI_ENOMEM;
2050   }
2051   _cmThread = _cm->cmThread();
2052 
2053   // Initialize the from_card cache structure of HeapRegionRemSet.
2054   HeapRegionRemSet::init_heap(max_regions());
2055 
2056   // Now expand into the initial heap size.
2057   if (!expand(init_byte_size)) {
2058     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2059     return JNI_ENOMEM;
2060   }
2061 
2062   // Perform any initialization actions delegated to the policy.
2063   g1_policy()->init();
2064 
2065   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2066                                                SATB_Q_FL_lock,
2067                                                G1SATBProcessCompletedThreshold,
2068                                                Shared_SATB_Q_lock);
2069 
2070   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2071                                                 DirtyCardQ_CBL_mon,
2072                                                 DirtyCardQ_FL_lock,
2073                                                 concurrent_g1_refine()->yellow_zone(),
2074                                                 concurrent_g1_refine()->red_zone(),
2075                                                 Shared_DirtyCardQ_lock);
2076 
2077   dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2078                                     DirtyCardQ_CBL_mon,
2079                                     DirtyCardQ_FL_lock,
2080                                     -1, // never trigger processing
2081                                     -1, // no limit on length
2082                                     Shared_DirtyCardQ_lock,
2083                                     &JavaThread::dirty_card_queue_set());
2084 
2085   // Initialize the card queue set used to hold cards containing
2086   // references into the collection set.
2087   _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2088                                              DirtyCardQ_CBL_mon,
2089                                              DirtyCardQ_FL_lock,
2090                                              -1, // never trigger processing
2091                                              -1, // no limit on length
2092                                              Shared_DirtyCardQ_lock,
2093                                              &JavaThread::dirty_card_queue_set());
2094 
2095   // Here we allocate the dummy HeapRegion that is required by the
2096   // G1AllocRegion class.
2097   HeapRegion* dummy_region = _hrm.get_dummy_region();
2098 
2099   // We'll re-use the same region whether the alloc region will
2100   // require BOT updates or not and, if it doesn't, then a non-young
2101   // region will complain that it cannot support allocations without
2102   // BOT updates. So we'll tag the dummy region as eden to avoid that.
2103   dummy_region->set_eden();
2104   // Make sure it's full.
2105   dummy_region->set_top(dummy_region->end());
2106   G1AllocRegion::setup(this, dummy_region);
2107 
2108   _allocator->init_mutator_alloc_region();
2109 
2110   // Do create of the monitoring and management support so that
2111   // values in the heap have been properly initialized.
2112   _g1mm = new G1MonitoringSupport(this);
2113 
2114   G1StringDedup::initialize();
2115 
2116   _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2117   for (uint i = 0; i < ParallelGCThreads; i++) {
2118     new (&_preserved_objs[i]) OopAndMarkOopStack();
2119   }
2120 
2121   return JNI_OK;
2122 }
2123 
2124 void G1CollectedHeap::stop() {
2125   // Stop all concurrent threads. We do this to make sure these threads
2126   // do not continue to execute and access resources (e.g. gclog_or_tty)
2127   // that are destroyed during shutdown.
2128   _cg1r->stop();
2129   _cmThread->stop();
2130   if (G1StringDedup::is_enabled()) {
2131     G1StringDedup::stop();
2132   }
2133 }
2134 
2135 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2136   return HeapRegion::max_region_size();
2137 }
2138 
2139 void G1CollectedHeap::post_initialize() {
2140   CollectedHeap::post_initialize();
2141   ref_processing_init();
2142 }
2143 
2144 void G1CollectedHeap::ref_processing_init() {
2145   // Reference processing in G1 currently works as follows:
2146   //
2147   // * There are two reference processor instances. One is
2148   //   used to record and process discovered references
2149   //   during concurrent marking; the other is used to
2150   //   record and process references during STW pauses
2151   //   (both full and incremental).
2152   // * Both ref processors need to 'span' the entire heap as
2153   //   the regions in the collection set may be dotted around.
2154   //
2155   // * For the concurrent marking ref processor:
2156   //   * Reference discovery is enabled at initial marking.
2157   //   * Reference discovery is disabled and the discovered
2158   //     references processed etc during remarking.
2159   //   * Reference discovery is MT (see below).
2160   //   * Reference discovery requires a barrier (see below).
2161   //   * Reference processing may or may not be MT
2162   //     (depending on the value of ParallelRefProcEnabled
2163   //     and ParallelGCThreads).
2164   //   * A full GC disables reference discovery by the CM
2165   //     ref processor and abandons any entries on it's
2166   //     discovered lists.
2167   //
2168   // * For the STW processor:
2169   //   * Non MT discovery is enabled at the start of a full GC.
2170   //   * Processing and enqueueing during a full GC is non-MT.
2171   //   * During a full GC, references are processed after marking.
2172   //
2173   //   * Discovery (may or may not be MT) is enabled at the start
2174   //     of an incremental evacuation pause.
2175   //   * References are processed near the end of a STW evacuation pause.
2176   //   * For both types of GC:
2177   //     * Discovery is atomic - i.e. not concurrent.
2178   //     * Reference discovery will not need a barrier.
2179 
2180   MemRegion mr = reserved_region();
2181 
2182   // Concurrent Mark ref processor
2183   _ref_processor_cm =
2184     new ReferenceProcessor(mr,    // span
2185                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2186                                 // mt processing
2187                            ParallelGCThreads,
2188                                 // degree of mt processing
2189                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2190                                 // mt discovery
2191                            MAX2(ParallelGCThreads, ConcGCThreads),
2192                                 // degree of mt discovery
2193                            false,
2194                                 // Reference discovery is not atomic
2195                            &_is_alive_closure_cm);
2196                                 // is alive closure
2197                                 // (for efficiency/performance)
2198 
2199   // STW ref processor
2200   _ref_processor_stw =
2201     new ReferenceProcessor(mr,    // span
2202                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2203                                 // mt processing
2204                            ParallelGCThreads,
2205                                 // degree of mt processing
2206                            (ParallelGCThreads > 1),
2207                                 // mt discovery
2208                            ParallelGCThreads,
2209                                 // degree of mt discovery
2210                            true,
2211                                 // Reference discovery is atomic
2212                            &_is_alive_closure_stw);
2213                                 // is alive closure
2214                                 // (for efficiency/performance)
2215 }
2216 
2217 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2218   return g1_policy();
2219 }
2220 
2221 size_t G1CollectedHeap::capacity() const {
2222   return _hrm.length() * HeapRegion::GrainBytes;
2223 }
2224 
2225 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2226   assert(!hr->is_continues_humongous(), "pre-condition");
2227   hr->reset_gc_time_stamp();
2228   if (hr->is_starts_humongous()) {
2229     uint first_index = hr->hrm_index() + 1;
2230     uint last_index = hr->last_hc_index();
2231     for (uint i = first_index; i < last_index; i += 1) {
2232       HeapRegion* chr = region_at(i);
2233       assert(chr->is_continues_humongous(), "sanity");
2234       chr->reset_gc_time_stamp();
2235     }
2236   }
2237 }
2238 
2239 #ifndef PRODUCT
2240 
2241 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2242 private:
2243   unsigned _gc_time_stamp;
2244   bool _failures;
2245 
2246 public:
2247   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2248     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2249 
2250   virtual bool doHeapRegion(HeapRegion* hr) {
2251     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2252     if (_gc_time_stamp != region_gc_time_stamp) {
2253       gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2254                              "expected %d", HR_FORMAT_PARAMS(hr),
2255                              region_gc_time_stamp, _gc_time_stamp);
2256       _failures = true;
2257     }
2258     return false;
2259   }
2260 
2261   bool failures() { return _failures; }
2262 };
2263 
2264 void G1CollectedHeap::check_gc_time_stamps() {
2265   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2266   heap_region_iterate(&cl);
2267   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2268 }
2269 #endif // PRODUCT
2270 
2271 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2272   _cg1r->hot_card_cache()->drain(cl, worker_i);
2273 }
2274 
2275 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2276   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2277   size_t n_completed_buffers = 0;
2278   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2279     n_completed_buffers++;
2280   }
2281   g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2282   dcqs.clear_n_completed_buffers();
2283   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2284 }
2285 
2286 // Computes the sum of the storage used by the various regions.
2287 size_t G1CollectedHeap::used() const {
2288   size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2289   if (_archive_allocator != NULL) {
2290     result += _archive_allocator->used();
2291   }
2292   return result;
2293 }
2294 
2295 size_t G1CollectedHeap::used_unlocked() const {
2296   return _summary_bytes_used;
2297 }
2298 
2299 class SumUsedClosure: public HeapRegionClosure {
2300   size_t _used;
2301 public:
2302   SumUsedClosure() : _used(0) {}
2303   bool doHeapRegion(HeapRegion* r) {
2304     if (!r->is_continues_humongous()) {
2305       _used += r->used();
2306     }
2307     return false;
2308   }
2309   size_t result() { return _used; }
2310 };
2311 
2312 size_t G1CollectedHeap::recalculate_used() const {
2313   double recalculate_used_start = os::elapsedTime();
2314 
2315   SumUsedClosure blk;
2316   heap_region_iterate(&blk);
2317 
2318   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2319   return blk.result();
2320 }
2321 
2322 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2323   switch (cause) {
2324     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2325     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2326     case GCCause::_dcmd_gc_run:             return ExplicitGCInvokesConcurrent;
2327     case GCCause::_g1_humongous_allocation: return true;
2328     case GCCause::_update_allocation_context_stats_inc: return true;
2329     case GCCause::_wb_conc_mark:            return true;
2330     default:                                return false;
2331   }
2332 }
2333 
2334 #ifndef PRODUCT
2335 void G1CollectedHeap::allocate_dummy_regions() {
2336   // Let's fill up most of the region
2337   size_t word_size = HeapRegion::GrainWords - 1024;
2338   // And as a result the region we'll allocate will be humongous.
2339   guarantee(is_humongous(word_size), "sanity");
2340 
2341   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2342     // Let's use the existing mechanism for the allocation
2343     HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2344                                                  AllocationContext::system());
2345     if (dummy_obj != NULL) {
2346       MemRegion mr(dummy_obj, word_size);
2347       CollectedHeap::fill_with_object(mr);
2348     } else {
2349       // If we can't allocate once, we probably cannot allocate
2350       // again. Let's get out of the loop.
2351       break;
2352     }
2353   }
2354 }
2355 #endif // !PRODUCT
2356 
2357 void G1CollectedHeap::increment_old_marking_cycles_started() {
2358   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2359          _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2360          "Wrong marking cycle count (started: %d, completed: %d)",
2361          _old_marking_cycles_started, _old_marking_cycles_completed);
2362 
2363   _old_marking_cycles_started++;
2364 }
2365 
2366 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2367   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2368 
2369   // We assume that if concurrent == true, then the caller is a
2370   // concurrent thread that was joined the Suspendible Thread
2371   // Set. If there's ever a cheap way to check this, we should add an
2372   // assert here.
2373 
2374   // Given that this method is called at the end of a Full GC or of a
2375   // concurrent cycle, and those can be nested (i.e., a Full GC can
2376   // interrupt a concurrent cycle), the number of full collections
2377   // completed should be either one (in the case where there was no
2378   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2379   // behind the number of full collections started.
2380 
2381   // This is the case for the inner caller, i.e. a Full GC.
2382   assert(concurrent ||
2383          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2384          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2385          "for inner caller (Full GC): _old_marking_cycles_started = %u "
2386          "is inconsistent with _old_marking_cycles_completed = %u",
2387          _old_marking_cycles_started, _old_marking_cycles_completed);
2388 
2389   // This is the case for the outer caller, i.e. the concurrent cycle.
2390   assert(!concurrent ||
2391          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2392          "for outer caller (concurrent cycle): "
2393          "_old_marking_cycles_started = %u "
2394          "is inconsistent with _old_marking_cycles_completed = %u",
2395          _old_marking_cycles_started, _old_marking_cycles_completed);
2396 
2397   _old_marking_cycles_completed += 1;
2398 
2399   // We need to clear the "in_progress" flag in the CM thread before
2400   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2401   // is set) so that if a waiter requests another System.gc() it doesn't
2402   // incorrectly see that a marking cycle is still in progress.
2403   if (concurrent) {
2404     _cmThread->set_idle();
2405   }
2406 
2407   // This notify_all() will ensure that a thread that called
2408   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2409   // and it's waiting for a full GC to finish will be woken up. It is
2410   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2411   FullGCCount_lock->notify_all();
2412 }
2413 
2414 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2415   GCIdMarkAndRestore conc_gc_id_mark;
2416   collector_state()->set_concurrent_cycle_started(true);
2417   _gc_timer_cm->register_gc_start(start_time);
2418 
2419   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2420   trace_heap_before_gc(_gc_tracer_cm);
2421   _cmThread->set_gc_id(GCId::current());
2422 }
2423 
2424 void G1CollectedHeap::register_concurrent_cycle_end() {
2425   if (collector_state()->concurrent_cycle_started()) {
2426     GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2427     if (_cm->has_aborted()) {
2428       _gc_tracer_cm->report_concurrent_mode_failure();
2429     }
2430 
2431     _gc_timer_cm->register_gc_end();
2432     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2433 
2434     // Clear state variables to prepare for the next concurrent cycle.
2435      collector_state()->set_concurrent_cycle_started(false);
2436     _heap_summary_sent = false;
2437   }
2438 }
2439 
2440 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2441   if (collector_state()->concurrent_cycle_started()) {
2442     // This function can be called when:
2443     //  the cleanup pause is run
2444     //  the concurrent cycle is aborted before the cleanup pause.
2445     //  the concurrent cycle is aborted after the cleanup pause,
2446     //   but before the concurrent cycle end has been registered.
2447     // Make sure that we only send the heap information once.
2448     if (!_heap_summary_sent) {
2449       GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2450       trace_heap_after_gc(_gc_tracer_cm);
2451       _heap_summary_sent = true;
2452     }
2453   }
2454 }
2455 
2456 void G1CollectedHeap::collect(GCCause::Cause cause) {
2457   assert_heap_not_locked();
2458 
2459   uint gc_count_before;
2460   uint old_marking_count_before;
2461   uint full_gc_count_before;
2462   bool retry_gc;
2463 
2464   do {
2465     retry_gc = false;
2466 
2467     {
2468       MutexLocker ml(Heap_lock);
2469 
2470       // Read the GC count while holding the Heap_lock
2471       gc_count_before = total_collections();
2472       full_gc_count_before = total_full_collections();
2473       old_marking_count_before = _old_marking_cycles_started;
2474     }
2475 
2476     if (should_do_concurrent_full_gc(cause)) {
2477       // Schedule an initial-mark evacuation pause that will start a
2478       // concurrent cycle. We're setting word_size to 0 which means that
2479       // we are not requesting a post-GC allocation.
2480       VM_G1IncCollectionPause op(gc_count_before,
2481                                  0,     /* word_size */
2482                                  true,  /* should_initiate_conc_mark */
2483                                  g1_policy()->max_pause_time_ms(),
2484                                  cause);
2485       op.set_allocation_context(AllocationContext::current());
2486 
2487       VMThread::execute(&op);
2488       if (!op.pause_succeeded()) {
2489         if (old_marking_count_before == _old_marking_cycles_started) {
2490           retry_gc = op.should_retry_gc();
2491         } else {
2492           // A Full GC happened while we were trying to schedule the
2493           // initial-mark GC. No point in starting a new cycle given
2494           // that the whole heap was collected anyway.
2495         }
2496 
2497         if (retry_gc) {
2498           if (GC_locker::is_active_and_needs_gc()) {
2499             GC_locker::stall_until_clear();
2500           }
2501         }
2502       }
2503     } else {
2504       if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2505           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2506 
2507         // Schedule a standard evacuation pause. We're setting word_size
2508         // to 0 which means that we are not requesting a post-GC allocation.
2509         VM_G1IncCollectionPause op(gc_count_before,
2510                                    0,     /* word_size */
2511                                    false, /* should_initiate_conc_mark */
2512                                    g1_policy()->max_pause_time_ms(),
2513                                    cause);
2514         VMThread::execute(&op);
2515       } else {
2516         // Schedule a Full GC.
2517         VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2518         VMThread::execute(&op);
2519       }
2520     }
2521   } while (retry_gc);
2522 }
2523 
2524 bool G1CollectedHeap::is_in(const void* p) const {
2525   if (_hrm.reserved().contains(p)) {
2526     // Given that we know that p is in the reserved space,
2527     // heap_region_containing_raw() should successfully
2528     // return the containing region.
2529     HeapRegion* hr = heap_region_containing_raw(p);
2530     return hr->is_in(p);
2531   } else {
2532     return false;
2533   }
2534 }
2535 
2536 #ifdef ASSERT
2537 bool G1CollectedHeap::is_in_exact(const void* p) const {
2538   bool contains = reserved_region().contains(p);
2539   bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2540   if (contains && available) {
2541     return true;
2542   } else {
2543     return false;
2544   }
2545 }
2546 #endif
2547 
2548 bool G1CollectedHeap::obj_in_cs(oop obj) {
2549   HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2550   return r != NULL && r->in_collection_set();
2551 }
2552 
2553 // Iteration functions.
2554 
2555 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2556 
2557 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2558   ExtendedOopClosure* _cl;
2559 public:
2560   IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2561   bool doHeapRegion(HeapRegion* r) {
2562     if (!r->is_continues_humongous()) {
2563       r->oop_iterate(_cl);
2564     }
2565     return false;
2566   }
2567 };
2568 
2569 // Iterates an ObjectClosure over all objects within a HeapRegion.
2570 
2571 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2572   ObjectClosure* _cl;
2573 public:
2574   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2575   bool doHeapRegion(HeapRegion* r) {
2576     if (!r->is_continues_humongous()) {
2577       r->object_iterate(_cl);
2578     }
2579     return false;
2580   }
2581 };
2582 
2583 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2584   IterateObjectClosureRegionClosure blk(cl);
2585   heap_region_iterate(&blk);
2586 }
2587 
2588 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2589   _hrm.iterate(cl);
2590 }
2591 
2592 void
2593 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2594                                          uint worker_id,
2595                                          HeapRegionClaimer *hrclaimer,
2596                                          bool concurrent) const {
2597   _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2598 }
2599 
2600 // Clear the cached CSet starting regions and (more importantly)
2601 // the time stamps. Called when we reset the GC time stamp.
2602 void G1CollectedHeap::clear_cset_start_regions() {
2603   assert(_worker_cset_start_region != NULL, "sanity");
2604   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2605 
2606   for (uint i = 0; i < ParallelGCThreads; i++) {
2607     _worker_cset_start_region[i] = NULL;
2608     _worker_cset_start_region_time_stamp[i] = 0;
2609   }
2610 }
2611 
2612 // Given the id of a worker, obtain or calculate a suitable
2613 // starting region for iterating over the current collection set.
2614 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2615   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2616 
2617   HeapRegion* result = NULL;
2618   unsigned gc_time_stamp = get_gc_time_stamp();
2619 
2620   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2621     // Cached starting region for current worker was set
2622     // during the current pause - so it's valid.
2623     // Note: the cached starting heap region may be NULL
2624     // (when the collection set is empty).
2625     result = _worker_cset_start_region[worker_i];
2626     assert(result == NULL || result->in_collection_set(), "sanity");
2627     return result;
2628   }
2629 
2630   // The cached entry was not valid so let's calculate
2631   // a suitable starting heap region for this worker.
2632 
2633   // We want the parallel threads to start their collection
2634   // set iteration at different collection set regions to
2635   // avoid contention.
2636   // If we have:
2637   //          n collection set regions
2638   //          p threads
2639   // Then thread t will start at region floor ((t * n) / p)
2640 
2641   result = g1_policy()->collection_set();
2642   uint cs_size = g1_policy()->cset_region_length();
2643   uint active_workers = workers()->active_workers();
2644 
2645   uint end_ind   = (cs_size * worker_i) / active_workers;
2646   uint start_ind = 0;
2647 
2648   if (worker_i > 0 &&
2649       _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2650     // Previous workers starting region is valid
2651     // so let's iterate from there
2652     start_ind = (cs_size * (worker_i - 1)) / active_workers;
2653     result = _worker_cset_start_region[worker_i - 1];
2654   }
2655 
2656   for (uint i = start_ind; i < end_ind; i++) {
2657     result = result->next_in_collection_set();
2658   }
2659 
2660   // Note: the calculated starting heap region may be NULL
2661   // (when the collection set is empty).
2662   assert(result == NULL || result->in_collection_set(), "sanity");
2663   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2664          "should be updated only once per pause");
2665   _worker_cset_start_region[worker_i] = result;
2666   OrderAccess::storestore();
2667   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2668   return result;
2669 }
2670 
2671 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2672   HeapRegion* r = g1_policy()->collection_set();
2673   while (r != NULL) {
2674     HeapRegion* next = r->next_in_collection_set();
2675     if (cl->doHeapRegion(r)) {
2676       cl->incomplete();
2677       return;
2678     }
2679     r = next;
2680   }
2681 }
2682 
2683 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2684                                                   HeapRegionClosure *cl) {
2685   if (r == NULL) {
2686     // The CSet is empty so there's nothing to do.
2687     return;
2688   }
2689 
2690   assert(r->in_collection_set(),
2691          "Start region must be a member of the collection set.");
2692   HeapRegion* cur = r;
2693   while (cur != NULL) {
2694     HeapRegion* next = cur->next_in_collection_set();
2695     if (cl->doHeapRegion(cur) && false) {
2696       cl->incomplete();
2697       return;
2698     }
2699     cur = next;
2700   }
2701   cur = g1_policy()->collection_set();
2702   while (cur != r) {
2703     HeapRegion* next = cur->next_in_collection_set();
2704     if (cl->doHeapRegion(cur) && false) {
2705       cl->incomplete();
2706       return;
2707     }
2708     cur = next;
2709   }
2710 }
2711 
2712 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2713   HeapRegion* result = _hrm.next_region_in_heap(from);
2714   while (result != NULL && result->is_pinned()) {
2715     result = _hrm.next_region_in_heap(result);
2716   }
2717   return result;
2718 }
2719 
2720 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2721   HeapRegion* hr = heap_region_containing(addr);
2722   return hr->block_start(addr);
2723 }
2724 
2725 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2726   HeapRegion* hr = heap_region_containing(addr);
2727   return hr->block_size(addr);
2728 }
2729 
2730 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2731   HeapRegion* hr = heap_region_containing(addr);
2732   return hr->block_is_obj(addr);
2733 }
2734 
2735 bool G1CollectedHeap::supports_tlab_allocation() const {
2736   return true;
2737 }
2738 
2739 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2740   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2741 }
2742 
2743 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2744   return young_list()->eden_used_bytes();
2745 }
2746 
2747 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2748 // must be equal to the humongous object limit.
2749 size_t G1CollectedHeap::max_tlab_size() const {
2750   return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2751 }
2752 
2753 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2754   AllocationContext_t context = AllocationContext::current();
2755   return _allocator->unsafe_max_tlab_alloc(context);
2756 }
2757 
2758 size_t G1CollectedHeap::max_capacity() const {
2759   return _hrm.reserved().byte_size();
2760 }
2761 
2762 jlong G1CollectedHeap::millis_since_last_gc() {
2763   // assert(false, "NYI");
2764   return 0;
2765 }
2766 
2767 void G1CollectedHeap::prepare_for_verify() {
2768   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2769     ensure_parsability(false);
2770   }
2771   g1_rem_set()->prepare_for_verify();
2772 }
2773 
2774 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2775                                               VerifyOption vo) {
2776   switch (vo) {
2777   case VerifyOption_G1UsePrevMarking:
2778     return hr->obj_allocated_since_prev_marking(obj);
2779   case VerifyOption_G1UseNextMarking:
2780     return hr->obj_allocated_since_next_marking(obj);
2781   case VerifyOption_G1UseMarkWord:
2782     return false;
2783   default:
2784     ShouldNotReachHere();
2785   }
2786   return false; // keep some compilers happy
2787 }
2788 
2789 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2790   switch (vo) {
2791   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2792   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2793   case VerifyOption_G1UseMarkWord:    return NULL;
2794   default:                            ShouldNotReachHere();
2795   }
2796   return NULL; // keep some compilers happy
2797 }
2798 
2799 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2800   switch (vo) {
2801   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2802   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2803   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
2804   default:                            ShouldNotReachHere();
2805   }
2806   return false; // keep some compilers happy
2807 }
2808 
2809 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2810   switch (vo) {
2811   case VerifyOption_G1UsePrevMarking: return "PTAMS";
2812   case VerifyOption_G1UseNextMarking: return "NTAMS";
2813   case VerifyOption_G1UseMarkWord:    return "NONE";
2814   default:                            ShouldNotReachHere();
2815   }
2816   return NULL; // keep some compilers happy
2817 }
2818 
2819 class VerifyRootsClosure: public OopClosure {
2820 private:
2821   G1CollectedHeap* _g1h;
2822   VerifyOption     _vo;
2823   bool             _failures;
2824 public:
2825   // _vo == UsePrevMarking -> use "prev" marking information,
2826   // _vo == UseNextMarking -> use "next" marking information,
2827   // _vo == UseMarkWord    -> use mark word from object header.
2828   VerifyRootsClosure(VerifyOption vo) :
2829     _g1h(G1CollectedHeap::heap()),
2830     _vo(vo),
2831     _failures(false) { }
2832 
2833   bool failures() { return _failures; }
2834 
2835   template <class T> void do_oop_nv(T* p) {
2836     T heap_oop = oopDesc::load_heap_oop(p);
2837     if (!oopDesc::is_null(heap_oop)) {
2838       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2839       if (_g1h->is_obj_dead_cond(obj, _vo)) {
2840         gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2841                                "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2842         if (_vo == VerifyOption_G1UseMarkWord) {
2843           gclog_or_tty->print_cr("  Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2844         }
2845         obj->print_on(gclog_or_tty);
2846         _failures = true;
2847       }
2848     }
2849   }
2850 
2851   void do_oop(oop* p)       { do_oop_nv(p); }
2852   void do_oop(narrowOop* p) { do_oop_nv(p); }
2853 };
2854 
2855 class G1VerifyCodeRootOopClosure: public OopClosure {
2856   G1CollectedHeap* _g1h;
2857   OopClosure* _root_cl;
2858   nmethod* _nm;
2859   VerifyOption _vo;
2860   bool _failures;
2861 
2862   template <class T> void do_oop_work(T* p) {
2863     // First verify that this root is live
2864     _root_cl->do_oop(p);
2865 
2866     if (!G1VerifyHeapRegionCodeRoots) {
2867       // We're not verifying the code roots attached to heap region.
2868       return;
2869     }
2870 
2871     // Don't check the code roots during marking verification in a full GC
2872     if (_vo == VerifyOption_G1UseMarkWord) {
2873       return;
2874     }
2875 
2876     // Now verify that the current nmethod (which contains p) is
2877     // in the code root list of the heap region containing the
2878     // object referenced by p.
2879 
2880     T heap_oop = oopDesc::load_heap_oop(p);
2881     if (!oopDesc::is_null(heap_oop)) {
2882       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2883 
2884       // Now fetch the region containing the object
2885       HeapRegion* hr = _g1h->heap_region_containing(obj);
2886       HeapRegionRemSet* hrrs = hr->rem_set();
2887       // Verify that the strong code root list for this region
2888       // contains the nmethod
2889       if (!hrrs->strong_code_roots_list_contains(_nm)) {
2890         gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2891                                "from nmethod " PTR_FORMAT " not in strong "
2892                                "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2893                                p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2894         _failures = true;
2895       }
2896     }
2897   }
2898 
2899 public:
2900   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2901     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2902 
2903   void do_oop(oop* p) { do_oop_work(p); }
2904   void do_oop(narrowOop* p) { do_oop_work(p); }
2905 
2906   void set_nmethod(nmethod* nm) { _nm = nm; }
2907   bool failures() { return _failures; }
2908 };
2909 
2910 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2911   G1VerifyCodeRootOopClosure* _oop_cl;
2912 
2913 public:
2914   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2915     _oop_cl(oop_cl) {}
2916 
2917   void do_code_blob(CodeBlob* cb) {
2918     nmethod* nm = cb->as_nmethod_or_null();
2919     if (nm != NULL) {
2920       _oop_cl->set_nmethod(nm);
2921       nm->oops_do(_oop_cl);
2922     }
2923   }
2924 };
2925 
2926 class YoungRefCounterClosure : public OopClosure {
2927   G1CollectedHeap* _g1h;
2928   int              _count;
2929  public:
2930   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2931   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
2932   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2933 
2934   int count() { return _count; }
2935   void reset_count() { _count = 0; };
2936 };
2937 
2938 class VerifyKlassClosure: public KlassClosure {
2939   YoungRefCounterClosure _young_ref_counter_closure;
2940   OopClosure *_oop_closure;
2941  public:
2942   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2943   void do_klass(Klass* k) {
2944     k->oops_do(_oop_closure);
2945 
2946     _young_ref_counter_closure.reset_count();
2947     k->oops_do(&_young_ref_counter_closure);
2948     if (_young_ref_counter_closure.count() > 0) {
2949       guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2950     }
2951   }
2952 };
2953 
2954 class VerifyLivenessOopClosure: public OopClosure {
2955   G1CollectedHeap* _g1h;
2956   VerifyOption _vo;
2957 public:
2958   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2959     _g1h(g1h), _vo(vo)
2960   { }
2961   void do_oop(narrowOop *p) { do_oop_work(p); }
2962   void do_oop(      oop *p) { do_oop_work(p); }
2963 
2964   template <class T> void do_oop_work(T *p) {
2965     oop obj = oopDesc::load_decode_heap_oop(p);
2966     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2967               "Dead object referenced by a not dead object");
2968   }
2969 };
2970 
2971 class VerifyObjsInRegionClosure: public ObjectClosure {
2972 private:
2973   G1CollectedHeap* _g1h;
2974   size_t _live_bytes;
2975   HeapRegion *_hr;
2976   VerifyOption _vo;
2977 public:
2978   // _vo == UsePrevMarking -> use "prev" marking information,
2979   // _vo == UseNextMarking -> use "next" marking information,
2980   // _vo == UseMarkWord    -> use mark word from object header.
2981   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2982     : _live_bytes(0), _hr(hr), _vo(vo) {
2983     _g1h = G1CollectedHeap::heap();
2984   }
2985   void do_object(oop o) {
2986     VerifyLivenessOopClosure isLive(_g1h, _vo);
2987     assert(o != NULL, "Huh?");
2988     if (!_g1h->is_obj_dead_cond(o, _vo)) {
2989       // If the object is alive according to the mark word,
2990       // then verify that the marking information agrees.
2991       // Note we can't verify the contra-positive of the
2992       // above: if the object is dead (according to the mark
2993       // word), it may not be marked, or may have been marked
2994       // but has since became dead, or may have been allocated
2995       // since the last marking.
2996       if (_vo == VerifyOption_G1UseMarkWord) {
2997         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2998       }
2999 
3000       o->oop_iterate_no_header(&isLive);
3001       if (!_hr->obj_allocated_since_prev_marking(o)) {
3002         size_t obj_size = o->size();    // Make sure we don't overflow
3003         _live_bytes += (obj_size * HeapWordSize);
3004       }
3005     }
3006   }
3007   size_t live_bytes() { return _live_bytes; }
3008 };
3009 
3010 class VerifyArchiveOopClosure: public OopClosure {
3011 public:
3012   VerifyArchiveOopClosure(HeapRegion *hr) { }
3013   void do_oop(narrowOop *p) { do_oop_work(p); }
3014   void do_oop(      oop *p) { do_oop_work(p); }
3015 
3016   template <class T> void do_oop_work(T *p) {
3017     oop obj = oopDesc::load_decode_heap_oop(p);
3018     guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3019               "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3020               p2i(p), p2i(obj));
3021   }
3022 };
3023 
3024 class VerifyArchiveRegionClosure: public ObjectClosure {
3025 public:
3026   VerifyArchiveRegionClosure(HeapRegion *hr) { }
3027   // Verify that all object pointers are to archive regions.
3028   void do_object(oop o) {
3029     VerifyArchiveOopClosure checkOop(NULL);
3030     assert(o != NULL, "Should not be here for NULL oops");
3031     o->oop_iterate_no_header(&checkOop);
3032   }
3033 };
3034 
3035 class VerifyRegionClosure: public HeapRegionClosure {
3036 private:
3037   bool             _par;
3038   VerifyOption     _vo;
3039   bool             _failures;
3040 public:
3041   // _vo == UsePrevMarking -> use "prev" marking information,
3042   // _vo == UseNextMarking -> use "next" marking information,
3043   // _vo == UseMarkWord    -> use mark word from object header.
3044   VerifyRegionClosure(bool par, VerifyOption vo)
3045     : _par(par),
3046       _vo(vo),
3047       _failures(false) {}
3048 
3049   bool failures() {
3050     return _failures;
3051   }
3052 
3053   bool doHeapRegion(HeapRegion* r) {
3054     // For archive regions, verify there are no heap pointers to
3055     // non-pinned regions. For all others, verify liveness info.
3056     if (r->is_archive()) {
3057       VerifyArchiveRegionClosure verify_oop_pointers(r);
3058       r->object_iterate(&verify_oop_pointers);
3059       return true;
3060     }
3061     if (!r->is_continues_humongous()) {
3062       bool failures = false;
3063       r->verify(_vo, &failures);
3064       if (failures) {
3065         _failures = true;
3066       } else {
3067         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3068         r->object_iterate(&not_dead_yet_cl);
3069         if (_vo != VerifyOption_G1UseNextMarking) {
3070           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3071             gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3072                                    "max_live_bytes " SIZE_FORMAT " "
3073                                    "< calculated " SIZE_FORMAT,
3074                                    p2i(r->bottom()), p2i(r->end()),
3075                                    r->max_live_bytes(),
3076                                  not_dead_yet_cl.live_bytes());
3077             _failures = true;
3078           }
3079         } else {
3080           // When vo == UseNextMarking we cannot currently do a sanity
3081           // check on the live bytes as the calculation has not been
3082           // finalized yet.
3083         }
3084       }
3085     }
3086     return false; // stop the region iteration if we hit a failure
3087   }
3088 };
3089 
3090 // This is the task used for parallel verification of the heap regions
3091 
3092 class G1ParVerifyTask: public AbstractGangTask {
3093 private:
3094   G1CollectedHeap*  _g1h;
3095   VerifyOption      _vo;
3096   bool              _failures;
3097   HeapRegionClaimer _hrclaimer;
3098 
3099 public:
3100   // _vo == UsePrevMarking -> use "prev" marking information,
3101   // _vo == UseNextMarking -> use "next" marking information,
3102   // _vo == UseMarkWord    -> use mark word from object header.
3103   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3104       AbstractGangTask("Parallel verify task"),
3105       _g1h(g1h),
3106       _vo(vo),
3107       _failures(false),
3108       _hrclaimer(g1h->workers()->active_workers()) {}
3109 
3110   bool failures() {
3111     return _failures;
3112   }
3113 
3114   void work(uint worker_id) {
3115     HandleMark hm;
3116     VerifyRegionClosure blk(true, _vo);
3117     _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3118     if (blk.failures()) {
3119       _failures = true;
3120     }
3121   }
3122 };
3123 
3124 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3125   if (SafepointSynchronize::is_at_safepoint()) {
3126     assert(Thread::current()->is_VM_thread(),
3127            "Expected to be executed serially by the VM thread at this point");
3128 
3129     if (!silent) { gclog_or_tty->print("Roots "); }
3130     VerifyRootsClosure rootsCl(vo);
3131     VerifyKlassClosure klassCl(this, &rootsCl);
3132     CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3133 
3134     // We apply the relevant closures to all the oops in the
3135     // system dictionary, class loader data graph, the string table
3136     // and the nmethods in the code cache.
3137     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3138     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3139 
3140     {
3141       G1RootProcessor root_processor(this, 1);
3142       root_processor.process_all_roots(&rootsCl,
3143                                        &cldCl,
3144                                        &blobsCl);
3145     }
3146 
3147     bool failures = rootsCl.failures() || codeRootsCl.failures();
3148 
3149     if (vo != VerifyOption_G1UseMarkWord) {
3150       // If we're verifying during a full GC then the region sets
3151       // will have been torn down at the start of the GC. Therefore
3152       // verifying the region sets will fail. So we only verify
3153       // the region sets when not in a full GC.
3154       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3155       verify_region_sets();
3156     }
3157 
3158     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3159     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3160 
3161       G1ParVerifyTask task(this, vo);
3162       workers()->run_task(&task);
3163       if (task.failures()) {
3164         failures = true;
3165       }
3166 
3167     } else {
3168       VerifyRegionClosure blk(false, vo);
3169       heap_region_iterate(&blk);
3170       if (blk.failures()) {
3171         failures = true;
3172       }
3173     }
3174 
3175     if (G1StringDedup::is_enabled()) {
3176       if (!silent) gclog_or_tty->print("StrDedup ");
3177       G1StringDedup::verify();
3178     }
3179 
3180     if (failures) {
3181       gclog_or_tty->print_cr("Heap:");
3182       // It helps to have the per-region information in the output to
3183       // help us track down what went wrong. This is why we call
3184       // print_extended_on() instead of print_on().
3185       print_extended_on(gclog_or_tty);
3186       gclog_or_tty->cr();
3187       gclog_or_tty->flush();
3188     }
3189     guarantee(!failures, "there should not have been any failures");
3190   } else {
3191     if (!silent) {
3192       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3193       if (G1StringDedup::is_enabled()) {
3194         gclog_or_tty->print(", StrDedup");
3195       }
3196       gclog_or_tty->print(") ");
3197     }
3198   }
3199 }
3200 
3201 void G1CollectedHeap::verify(bool silent) {
3202   verify(silent, VerifyOption_G1UsePrevMarking);
3203 }
3204 
3205 double G1CollectedHeap::verify(bool guard, const char* msg) {
3206   double verify_time_ms = 0.0;
3207 
3208   if (guard && total_collections() >= VerifyGCStartAt) {
3209     double verify_start = os::elapsedTime();
3210     HandleMark hm;  // Discard invalid handles created during verification
3211     prepare_for_verify();
3212     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3213     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3214   }
3215 
3216   return verify_time_ms;
3217 }
3218 
3219 void G1CollectedHeap::verify_before_gc() {
3220   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3221   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3222 }
3223 
3224 void G1CollectedHeap::verify_after_gc() {
3225   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3226   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3227 }
3228 
3229 class PrintRegionClosure: public HeapRegionClosure {
3230   outputStream* _st;
3231 public:
3232   PrintRegionClosure(outputStream* st) : _st(st) {}
3233   bool doHeapRegion(HeapRegion* r) {
3234     r->print_on(_st);
3235     return false;
3236   }
3237 };
3238 
3239 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3240                                        const HeapRegion* hr,
3241                                        const VerifyOption vo) const {
3242   switch (vo) {
3243   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3244   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3245   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked() && !hr->is_archive();
3246   default:                            ShouldNotReachHere();
3247   }
3248   return false; // keep some compilers happy
3249 }
3250 
3251 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3252                                        const VerifyOption vo) const {
3253   switch (vo) {
3254   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3255   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3256   case VerifyOption_G1UseMarkWord: {
3257     HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3258     return !obj->is_gc_marked() && !hr->is_archive();
3259   }
3260   default:                            ShouldNotReachHere();
3261   }
3262   return false; // keep some compilers happy
3263 }
3264 
3265 void G1CollectedHeap::print_on(outputStream* st) const {
3266   st->print(" %-20s", "garbage-first heap");
3267   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3268             capacity()/K, used_unlocked()/K);
3269   st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3270             p2i(_hrm.reserved().start()),
3271             p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3272             p2i(_hrm.reserved().end()));
3273   st->cr();
3274   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3275   uint young_regions = _young_list->length();
3276   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3277             (size_t) young_regions * HeapRegion::GrainBytes / K);
3278   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3279   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3280             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3281   st->cr();
3282   MetaspaceAux::print_on(st);
3283 }
3284 
3285 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3286   print_on(st);
3287 
3288   // Print the per-region information.
3289   st->cr();
3290   st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3291                "HS=humongous(starts), HC=humongous(continues), "
3292                "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3293                "PTAMS=previous top-at-mark-start, "
3294                "NTAMS=next top-at-mark-start)");
3295   PrintRegionClosure blk(st);
3296   heap_region_iterate(&blk);
3297 }
3298 
3299 void G1CollectedHeap::print_on_error(outputStream* st) const {
3300   this->CollectedHeap::print_on_error(st);
3301 
3302   if (_cm != NULL) {
3303     st->cr();
3304     _cm->print_on_error(st);
3305   }
3306 }
3307 
3308 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3309   workers()->print_worker_threads_on(st);
3310   _cmThread->print_on(st);
3311   st->cr();
3312   _cm->print_worker_threads_on(st);
3313   _cg1r->print_worker_threads_on(st);
3314   if (G1StringDedup::is_enabled()) {
3315     G1StringDedup::print_worker_threads_on(st);
3316   }
3317 }
3318 
3319 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3320   workers()->threads_do(tc);
3321   tc->do_thread(_cmThread);
3322   _cg1r->threads_do(tc);
3323   if (G1StringDedup::is_enabled()) {
3324     G1StringDedup::threads_do(tc);
3325   }
3326 }
3327 
3328 void G1CollectedHeap::print_tracing_info() const {
3329   // We'll overload this to mean "trace GC pause statistics."
3330   if (TraceYoungGenTime || TraceOldGenTime) {
3331     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3332     // to that.
3333     g1_policy()->print_tracing_info();
3334   }
3335   if (G1SummarizeRSetStats) {
3336     g1_rem_set()->print_summary_info();
3337   }
3338   if (G1SummarizeConcMark) {
3339     concurrent_mark()->print_summary_info();
3340   }
3341   g1_policy()->print_yg_surv_rate_info();
3342 }
3343 
3344 #ifndef PRODUCT
3345 // Helpful for debugging RSet issues.
3346 
3347 class PrintRSetsClosure : public HeapRegionClosure {
3348 private:
3349   const char* _msg;
3350   size_t _occupied_sum;
3351 
3352 public:
3353   bool doHeapRegion(HeapRegion* r) {
3354     HeapRegionRemSet* hrrs = r->rem_set();
3355     size_t occupied = hrrs->occupied();
3356     _occupied_sum += occupied;
3357 
3358     gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3359                            HR_FORMAT_PARAMS(r));
3360     if (occupied == 0) {
3361       gclog_or_tty->print_cr("  RSet is empty");
3362     } else {
3363       hrrs->print();
3364     }
3365     gclog_or_tty->print_cr("----------");
3366     return false;
3367   }
3368 
3369   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3370     gclog_or_tty->cr();
3371     gclog_or_tty->print_cr("========================================");
3372     gclog_or_tty->print_cr("%s", msg);
3373     gclog_or_tty->cr();
3374   }
3375 
3376   ~PrintRSetsClosure() {
3377     gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3378     gclog_or_tty->print_cr("========================================");
3379     gclog_or_tty->cr();
3380   }
3381 };
3382 
3383 void G1CollectedHeap::print_cset_rsets() {
3384   PrintRSetsClosure cl("Printing CSet RSets");
3385   collection_set_iterate(&cl);
3386 }
3387 
3388 void G1CollectedHeap::print_all_rsets() {
3389   PrintRSetsClosure cl("Printing All RSets");;
3390   heap_region_iterate(&cl);
3391 }
3392 #endif // PRODUCT
3393 
3394 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3395   YoungList* young_list = heap()->young_list();
3396 
3397   size_t eden_used_bytes = young_list->eden_used_bytes();
3398   size_t survivor_used_bytes = young_list->survivor_used_bytes();
3399 
3400   size_t eden_capacity_bytes =
3401     (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3402 
3403   VirtualSpaceSummary heap_summary = create_heap_space_summary();
3404   return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3405 }
3406 
3407 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3408   return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3409                        stats->unused(), stats->used(), stats->region_end_waste(),
3410                        stats->regions_filled(), stats->direct_allocated(),
3411                        stats->failure_used(), stats->failure_waste());
3412 }
3413 
3414 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3415   const G1HeapSummary& heap_summary = create_g1_heap_summary();
3416   gc_tracer->report_gc_heap_summary(when, heap_summary);
3417 
3418   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3419   gc_tracer->report_metaspace_summary(when, metaspace_summary);
3420 }
3421 
3422 
3423 G1CollectedHeap* G1CollectedHeap::heap() {
3424   CollectedHeap* heap = Universe::heap();
3425   assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3426   assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3427   return (G1CollectedHeap*)heap;
3428 }
3429 
3430 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3431   // always_do_update_barrier = false;
3432   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3433   // Fill TLAB's and such
3434   accumulate_statistics_all_tlabs();
3435   ensure_parsability(true);
3436 
3437   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3438       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3439     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3440   }
3441 }
3442 
3443 void G1CollectedHeap::gc_epilogue(bool full) {
3444 
3445   if (G1SummarizeRSetStats &&
3446       (G1SummarizeRSetStatsPeriod > 0) &&
3447       // we are at the end of the GC. Total collections has already been increased.
3448       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3449     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3450   }
3451 
3452   // FIXME: what is this about?
3453   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3454   // is set.
3455 #if defined(COMPILER2) || INCLUDE_JVMCI
3456   assert(DerivedPointerTable::is_empty(), "derived pointer present");
3457 #endif
3458   // always_do_update_barrier = true;
3459 
3460   resize_all_tlabs();
3461   allocation_context_stats().update(full);
3462 
3463   // We have just completed a GC. Update the soft reference
3464   // policy with the new heap occupancy
3465   Universe::update_heap_info_at_gc();
3466 }
3467 
3468 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3469                                                uint gc_count_before,
3470                                                bool* succeeded,
3471                                                GCCause::Cause gc_cause) {
3472   assert_heap_not_locked_and_not_at_safepoint();
3473   g1_policy()->record_stop_world_start();
3474   VM_G1IncCollectionPause op(gc_count_before,
3475                              word_size,
3476                              false, /* should_initiate_conc_mark */
3477                              g1_policy()->max_pause_time_ms(),
3478                              gc_cause);
3479 
3480   op.set_allocation_context(AllocationContext::current());
3481   VMThread::execute(&op);
3482 
3483   HeapWord* result = op.result();
3484   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3485   assert(result == NULL || ret_succeeded,
3486          "the result should be NULL if the VM did not succeed");
3487   *succeeded = ret_succeeded;
3488 
3489   assert_heap_not_locked();
3490   return result;
3491 }
3492 
3493 void
3494 G1CollectedHeap::doConcurrentMark() {
3495   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3496   if (!_cmThread->in_progress()) {
3497     _cmThread->set_started();
3498     CGC_lock->notify();
3499   }
3500 }
3501 
3502 size_t G1CollectedHeap::pending_card_num() {
3503   size_t extra_cards = 0;
3504   JavaThread *curr = Threads::first();
3505   while (curr != NULL) {
3506     DirtyCardQueue& dcq = curr->dirty_card_queue();
3507     extra_cards += dcq.size();
3508     curr = curr->next();
3509   }
3510   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3511   size_t buffer_size = dcqs.buffer_size();
3512   size_t buffer_num = dcqs.completed_buffers_num();
3513 
3514   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3515   // in bytes - not the number of 'entries'. We need to convert
3516   // into a number of cards.
3517   return (buffer_size * buffer_num + extra_cards) / oopSize;
3518 }
3519 
3520 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3521  private:
3522   size_t _total_humongous;
3523   size_t _candidate_humongous;
3524 
3525   DirtyCardQueue _dcq;
3526 
3527   // We don't nominate objects with many remembered set entries, on
3528   // the assumption that such objects are likely still live.
3529   bool is_remset_small(HeapRegion* region) const {
3530     HeapRegionRemSet* const rset = region->rem_set();
3531     return G1EagerReclaimHumongousObjectsWithStaleRefs
3532       ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3533       : rset->is_empty();
3534   }
3535 
3536   bool is_typeArray_region(HeapRegion* region) const {
3537     return oop(region->bottom())->is_typeArray();
3538   }
3539 
3540   bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3541     assert(region->is_starts_humongous(), "Must start a humongous object");
3542 
3543     // Candidate selection must satisfy the following constraints
3544     // while concurrent marking is in progress:
3545     //
3546     // * In order to maintain SATB invariants, an object must not be
3547     // reclaimed if it was allocated before the start of marking and
3548     // has not had its references scanned.  Such an object must have
3549     // its references (including type metadata) scanned to ensure no
3550     // live objects are missed by the marking process.  Objects
3551     // allocated after the start of concurrent marking don't need to
3552     // be scanned.
3553     //
3554     // * An object must not be reclaimed if it is on the concurrent
3555     // mark stack.  Objects allocated after the start of concurrent
3556     // marking are never pushed on the mark stack.
3557     //
3558     // Nominating only objects allocated after the start of concurrent
3559     // marking is sufficient to meet both constraints.  This may miss
3560     // some objects that satisfy the constraints, but the marking data
3561     // structures don't support efficiently performing the needed
3562     // additional tests or scrubbing of the mark stack.
3563     //
3564     // However, we presently only nominate is_typeArray() objects.
3565     // A humongous object containing references induces remembered
3566     // set entries on other regions.  In order to reclaim such an
3567     // object, those remembered sets would need to be cleaned up.
3568     //
3569     // We also treat is_typeArray() objects specially, allowing them
3570     // to be reclaimed even if allocated before the start of
3571     // concurrent mark.  For this we rely on mark stack insertion to
3572     // exclude is_typeArray() objects, preventing reclaiming an object
3573     // that is in the mark stack.  We also rely on the metadata for
3574     // such objects to be built-in and so ensured to be kept live.
3575     // Frequent allocation and drop of large binary blobs is an
3576     // important use case for eager reclaim, and this special handling
3577     // may reduce needed headroom.
3578 
3579     return is_typeArray_region(region) && is_remset_small(region);
3580   }
3581 
3582  public:
3583   RegisterHumongousWithInCSetFastTestClosure()
3584   : _total_humongous(0),
3585     _candidate_humongous(0),
3586     _dcq(&JavaThread::dirty_card_queue_set()) {
3587   }
3588 
3589   virtual bool doHeapRegion(HeapRegion* r) {
3590     if (!r->is_starts_humongous()) {
3591       return false;
3592     }
3593     G1CollectedHeap* g1h = G1CollectedHeap::heap();
3594 
3595     bool is_candidate = humongous_region_is_candidate(g1h, r);
3596     uint rindex = r->hrm_index();
3597     g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3598     if (is_candidate) {
3599       _candidate_humongous++;
3600       g1h->register_humongous_region_with_cset(rindex);
3601       // Is_candidate already filters out humongous object with large remembered sets.
3602       // If we have a humongous object with a few remembered sets, we simply flush these
3603       // remembered set entries into the DCQS. That will result in automatic
3604       // re-evaluation of their remembered set entries during the following evacuation
3605       // phase.
3606       if (!r->rem_set()->is_empty()) {
3607         guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3608                   "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3609         G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3610         HeapRegionRemSetIterator hrrs(r->rem_set());
3611         size_t card_index;
3612         while (hrrs.has_next(card_index)) {
3613           jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3614           // The remembered set might contain references to already freed
3615           // regions. Filter out such entries to avoid failing card table
3616           // verification.
3617           if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3618             if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3619               *card_ptr = CardTableModRefBS::dirty_card_val();
3620               _dcq.enqueue(card_ptr);
3621             }
3622           }
3623         }
3624         r->rem_set()->clear_locked();
3625       }
3626       assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3627     }
3628     _total_humongous++;
3629 
3630     return false;
3631   }
3632 
3633   size_t total_humongous() const { return _total_humongous; }
3634   size_t candidate_humongous() const { return _candidate_humongous; }
3635 
3636   void flush_rem_set_entries() { _dcq.flush(); }
3637 };
3638 
3639 void G1CollectedHeap::register_humongous_regions_with_cset() {
3640   if (!G1EagerReclaimHumongousObjects) {
3641     g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3642     return;
3643   }
3644   double time = os::elapsed_counter();
3645 
3646   // Collect reclaim candidate information and register candidates with cset.
3647   RegisterHumongousWithInCSetFastTestClosure cl;
3648   heap_region_iterate(&cl);
3649 
3650   time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3651   g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3652                                                                   cl.total_humongous(),
3653                                                                   cl.candidate_humongous());
3654   _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3655 
3656   // Finally flush all remembered set entries to re-check into the global DCQS.
3657   cl.flush_rem_set_entries();
3658 }
3659 
3660 #ifdef ASSERT
3661 class VerifyCSetClosure: public HeapRegionClosure {
3662 public:
3663   bool doHeapRegion(HeapRegion* hr) {
3664     // Here we check that the CSet region's RSet is ready for parallel
3665     // iteration. The fields that we'll verify are only manipulated
3666     // when the region is part of a CSet and is collected. Afterwards,
3667     // we reset these fields when we clear the region's RSet (when the
3668     // region is freed) so they are ready when the region is
3669     // re-allocated. The only exception to this is if there's an
3670     // evacuation failure and instead of freeing the region we leave
3671     // it in the heap. In that case, we reset these fields during
3672     // evacuation failure handling.
3673     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3674 
3675     // Here's a good place to add any other checks we'd like to
3676     // perform on CSet regions.
3677     return false;
3678   }
3679 };
3680 #endif // ASSERT
3681 
3682 uint G1CollectedHeap::num_task_queues() const {
3683   return _task_queues->size();
3684 }
3685 
3686 #if TASKQUEUE_STATS
3687 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3688   st->print_raw_cr("GC Task Stats");
3689   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3690   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3691 }
3692 
3693 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3694   print_taskqueue_stats_hdr(st);
3695 
3696   TaskQueueStats totals;
3697   const uint n = num_task_queues();
3698   for (uint i = 0; i < n; ++i) {
3699     st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3700     totals += task_queue(i)->stats;
3701   }
3702   st->print_raw("tot "); totals.print(st); st->cr();
3703 
3704   DEBUG_ONLY(totals.verify());
3705 }
3706 
3707 void G1CollectedHeap::reset_taskqueue_stats() {
3708   const uint n = num_task_queues();
3709   for (uint i = 0; i < n; ++i) {
3710     task_queue(i)->stats.reset();
3711   }
3712 }
3713 #endif // TASKQUEUE_STATS
3714 
3715 void G1CollectedHeap::log_gc_header() {
3716   if (!G1Log::fine()) {
3717     return;
3718   }
3719 
3720   gclog_or_tty->gclog_stamp();
3721 
3722   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3723     .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3724     .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3725 
3726   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3727 }
3728 
3729 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3730   if (!G1Log::fine()) {
3731     return;
3732   }
3733 
3734   if (G1Log::finer()) {
3735     if (evacuation_failed()) {
3736       gclog_or_tty->print(" (to-space exhausted)");
3737     }
3738     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3739     g1_policy()->print_phases(pause_time_sec);
3740     g1_policy()->print_detailed_heap_transition();
3741   } else {
3742     if (evacuation_failed()) {
3743       gclog_or_tty->print("--");
3744     }
3745     g1_policy()->print_heap_transition();
3746     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3747   }
3748   gclog_or_tty->flush();
3749 }
3750 
3751 void G1CollectedHeap::wait_for_root_region_scanning() {
3752   double scan_wait_start = os::elapsedTime();
3753   // We have to wait until the CM threads finish scanning the
3754   // root regions as it's the only way to ensure that all the
3755   // objects on them have been correctly scanned before we start
3756   // moving them during the GC.
3757   bool waited = _cm->root_regions()->wait_until_scan_finished();
3758   double wait_time_ms = 0.0;
3759   if (waited) {
3760     double scan_wait_end = os::elapsedTime();
3761     wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3762   }
3763   g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3764 }
3765 
3766 bool
3767 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3768   assert_at_safepoint(true /* should_be_vm_thread */);
3769   guarantee(!is_gc_active(), "collection is not reentrant");
3770 
3771   if (GC_locker::check_active_before_gc()) {
3772     return false;
3773   }
3774 
3775   _gc_timer_stw->register_gc_start();
3776 
3777   GCIdMark gc_id_mark;
3778   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3779 
3780   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3781   ResourceMark rm;
3782 
3783   wait_for_root_region_scanning();
3784 
3785   G1Log::update_level();
3786   print_heap_before_gc();
3787   trace_heap_before_gc(_gc_tracer_stw);
3788 
3789   verify_region_sets_optional();
3790   verify_dirty_young_regions();
3791 
3792   // This call will decide whether this pause is an initial-mark
3793   // pause. If it is, during_initial_mark_pause() will return true
3794   // for the duration of this pause.
3795   g1_policy()->decide_on_conc_mark_initiation();
3796 
3797   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3798   assert(!collector_state()->during_initial_mark_pause() ||
3799           collector_state()->gcs_are_young(), "sanity");
3800 
3801   // We also do not allow mixed GCs during marking.
3802   assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3803 
3804   // Record whether this pause is an initial mark. When the current
3805   // thread has completed its logging output and it's safe to signal
3806   // the CM thread, the flag's value in the policy has been reset.
3807   bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3808 
3809   // Inner scope for scope based logging, timers, and stats collection
3810   {
3811     EvacuationInfo evacuation_info;
3812 
3813     if (collector_state()->during_initial_mark_pause()) {
3814       // We are about to start a marking cycle, so we increment the
3815       // full collection counter.
3816       increment_old_marking_cycles_started();
3817       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3818     }
3819 
3820     _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3821 
3822     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3823 
3824     uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3825                                                                   workers()->active_workers(),
3826                                                                   Threads::number_of_non_daemon_threads());
3827     workers()->set_active_workers(active_workers);
3828 
3829     double pause_start_sec = os::elapsedTime();
3830     g1_policy()->note_gc_start(active_workers);
3831     log_gc_header();
3832 
3833     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3834     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3835 
3836     // If the secondary_free_list is not empty, append it to the
3837     // free_list. No need to wait for the cleanup operation to finish;
3838     // the region allocation code will check the secondary_free_list
3839     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3840     // set, skip this step so that the region allocation code has to
3841     // get entries from the secondary_free_list.
3842     if (!G1StressConcRegionFreeing) {
3843       append_secondary_free_list_if_not_empty_with_lock();
3844     }
3845 
3846     assert(check_young_list_well_formed(), "young list should be well formed");
3847 
3848     // Don't dynamically change the number of GC threads this early.  A value of
3849     // 0 is used to indicate serial work.  When parallel work is done,
3850     // it will be set.
3851 
3852     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3853       IsGCActiveMark x;
3854 
3855       gc_prologue(false);
3856       increment_total_collections(false /* full gc */);
3857       increment_gc_time_stamp();
3858 
3859       verify_before_gc();
3860 
3861       check_bitmaps("GC Start");
3862 
3863 #if defined(COMPILER2) || INCLUDE_JVMCI
3864       DerivedPointerTable::clear();
3865 #endif
3866 
3867       // Please see comment in g1CollectedHeap.hpp and
3868       // G1CollectedHeap::ref_processing_init() to see how
3869       // reference processing currently works in G1.
3870 
3871       // Enable discovery in the STW reference processor
3872       ref_processor_stw()->enable_discovery();
3873 
3874       {
3875         // We want to temporarily turn off discovery by the
3876         // CM ref processor, if necessary, and turn it back on
3877         // on again later if we do. Using a scoped
3878         // NoRefDiscovery object will do this.
3879         NoRefDiscovery no_cm_discovery(ref_processor_cm());
3880 
3881         // Forget the current alloc region (we might even choose it to be part
3882         // of the collection set!).
3883         _allocator->release_mutator_alloc_region();
3884 
3885         // We should call this after we retire the mutator alloc
3886         // region(s) so that all the ALLOC / RETIRE events are generated
3887         // before the start GC event.
3888         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3889 
3890         // This timing is only used by the ergonomics to handle our pause target.
3891         // It is unclear why this should not include the full pause. We will
3892         // investigate this in CR 7178365.
3893         //
3894         // Preserving the old comment here if that helps the investigation:
3895         //
3896         // The elapsed time induced by the start time below deliberately elides
3897         // the possible verification above.
3898         double sample_start_time_sec = os::elapsedTime();
3899 
3900         g1_policy()->record_collection_pause_start(sample_start_time_sec);
3901 
3902         if (collector_state()->during_initial_mark_pause()) {
3903           concurrent_mark()->checkpointRootsInitialPre();
3904         }
3905 
3906         double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3907         g1_policy()->finalize_old_cset_part(time_remaining_ms);
3908 
3909         evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3910 
3911         register_humongous_regions_with_cset();
3912 
3913         assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3914 
3915         _cm->note_start_of_gc();
3916         // We call this after finalize_cset() to
3917         // ensure that the CSet has been finalized.
3918         _cm->verify_no_cset_oops();
3919 
3920         if (_hr_printer.is_active()) {
3921           HeapRegion* hr = g1_policy()->collection_set();
3922           while (hr != NULL) {
3923             _hr_printer.cset(hr);
3924             hr = hr->next_in_collection_set();
3925           }
3926         }
3927 
3928 #ifdef ASSERT
3929         VerifyCSetClosure cl;
3930         collection_set_iterate(&cl);
3931 #endif // ASSERT
3932 
3933         // Initialize the GC alloc regions.
3934         _allocator->init_gc_alloc_regions(evacuation_info);
3935 
3936         G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3937         pre_evacuate_collection_set();
3938 
3939         // Actually do the work...
3940         evacuate_collection_set(evacuation_info, &per_thread_states);
3941 
3942         post_evacuate_collection_set(evacuation_info, &per_thread_states);
3943 
3944         const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3945         free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3946 
3947         eagerly_reclaim_humongous_regions();
3948 
3949         g1_policy()->clear_collection_set();
3950 
3951         // Start a new incremental collection set for the next pause.
3952         g1_policy()->start_incremental_cset_building();
3953 
3954         clear_cset_fast_test();
3955 
3956         _young_list->reset_sampled_info();
3957 
3958         // Don't check the whole heap at this point as the
3959         // GC alloc regions from this pause have been tagged
3960         // as survivors and moved on to the survivor list.
3961         // Survivor regions will fail the !is_young() check.
3962         assert(check_young_list_empty(false /* check_heap */),
3963           "young list should be empty");
3964 
3965         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3966                                              _young_list->first_survivor_region(),
3967                                              _young_list->last_survivor_region());
3968 
3969         _young_list->reset_auxilary_lists();
3970 
3971         if (evacuation_failed()) {
3972           set_used(recalculate_used());
3973           if (_archive_allocator != NULL) {
3974             _archive_allocator->clear_used();
3975           }
3976           for (uint i = 0; i < ParallelGCThreads; i++) {
3977             if (_evacuation_failed_info_array[i].has_failed()) {
3978               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3979             }
3980           }
3981         } else {
3982           // The "used" of the the collection set have already been subtracted
3983           // when they were freed.  Add in the bytes evacuated.
3984           increase_used(g1_policy()->bytes_copied_during_gc());
3985         }
3986 
3987         if (collector_state()->during_initial_mark_pause()) {
3988           // We have to do this before we notify the CM threads that
3989           // they can start working to make sure that all the
3990           // appropriate initialization is done on the CM object.
3991           concurrent_mark()->checkpointRootsInitialPost();
3992           collector_state()->set_mark_in_progress(true);
3993           // Note that we don't actually trigger the CM thread at
3994           // this point. We do that later when we're sure that
3995           // the current thread has completed its logging output.
3996         }
3997 
3998         allocate_dummy_regions();
3999 
4000         _allocator->init_mutator_alloc_region();
4001 
4002         {
4003           size_t expand_bytes = g1_policy()->expansion_amount();
4004           if (expand_bytes > 0) {
4005             size_t bytes_before = capacity();
4006             // No need for an ergo verbose message here,
4007             // expansion_amount() does this when it returns a value > 0.
4008             double expand_ms;
4009             if (!expand(expand_bytes, &expand_ms)) {
4010               // We failed to expand the heap. Cannot do anything about it.
4011             }
4012             g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
4013           }
4014         }
4015 
4016         // We redo the verification but now wrt to the new CSet which
4017         // has just got initialized after the previous CSet was freed.
4018         _cm->verify_no_cset_oops();
4019         _cm->note_end_of_gc();
4020 
4021         // This timing is only used by the ergonomics to handle our pause target.
4022         // It is unclear why this should not include the full pause. We will
4023         // investigate this in CR 7178365.
4024         double sample_end_time_sec = os::elapsedTime();
4025         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4026         size_t total_cards_scanned = per_thread_states.total_cards_scanned();
4027         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
4028 
4029         evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
4030         evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
4031 
4032         MemoryService::track_memory_usage();
4033 
4034         // In prepare_for_verify() below we'll need to scan the deferred
4035         // update buffers to bring the RSets up-to-date if
4036         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4037         // the update buffers we'll probably need to scan cards on the
4038         // regions we just allocated to (i.e., the GC alloc
4039         // regions). However, during the last GC we called
4040         // set_saved_mark() on all the GC alloc regions, so card
4041         // scanning might skip the [saved_mark_word()...top()] area of
4042         // those regions (i.e., the area we allocated objects into
4043         // during the last GC). But it shouldn't. Given that
4044         // saved_mark_word() is conditional on whether the GC time stamp
4045         // on the region is current or not, by incrementing the GC time
4046         // stamp here we invalidate all the GC time stamps on all the
4047         // regions and saved_mark_word() will simply return top() for
4048         // all the regions. This is a nicer way of ensuring this rather
4049         // than iterating over the regions and fixing them. In fact, the
4050         // GC time stamp increment here also ensures that
4051         // saved_mark_word() will return top() between pauses, i.e.,
4052         // during concurrent refinement. So we don't need the
4053         // is_gc_active() check to decided which top to use when
4054         // scanning cards (see CR 7039627).
4055         increment_gc_time_stamp();
4056 
4057         verify_after_gc();
4058         check_bitmaps("GC End");
4059 
4060         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4061         ref_processor_stw()->verify_no_references_recorded();
4062 
4063         // CM reference discovery will be re-enabled if necessary.
4064       }
4065 
4066       // We should do this after we potentially expand the heap so
4067       // that all the COMMIT events are generated before the end GC
4068       // event, and after we retire the GC alloc regions so that all
4069       // RETIRE events are generated before the end GC event.
4070       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4071 
4072 #ifdef TRACESPINNING
4073       ParallelTaskTerminator::print_termination_counts();
4074 #endif
4075 
4076       gc_epilogue(false);
4077     }
4078 
4079     // Print the remainder of the GC log output.
4080     log_gc_footer(os::elapsedTime() - pause_start_sec);
4081 
4082     // It is not yet to safe to tell the concurrent mark to
4083     // start as we have some optional output below. We don't want the
4084     // output from the concurrent mark thread interfering with this
4085     // logging output either.
4086 
4087     _hrm.verify_optional();
4088     verify_region_sets_optional();
4089 
4090     TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4091     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4092 
4093     print_heap_after_gc();
4094     trace_heap_after_gc(_gc_tracer_stw);
4095 
4096     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4097     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4098     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4099     // before any GC notifications are raised.
4100     g1mm()->update_sizes();
4101 
4102     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4103     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4104     _gc_timer_stw->register_gc_end();
4105     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4106   }
4107   // It should now be safe to tell the concurrent mark thread to start
4108   // without its logging output interfering with the logging output
4109   // that came from the pause.
4110 
4111   if (should_start_conc_mark) {
4112     // CAUTION: after the doConcurrentMark() call below,
4113     // the concurrent marking thread(s) could be running
4114     // concurrently with us. Make sure that anything after
4115     // this point does not assume that we are the only GC thread
4116     // running. Note: of course, the actual marking work will
4117     // not start until the safepoint itself is released in
4118     // SuspendibleThreadSet::desynchronize().
4119     doConcurrentMark();
4120   }
4121 
4122   return true;
4123 }
4124 
4125 void G1CollectedHeap::remove_self_forwarding_pointers() {
4126   double remove_self_forwards_start = os::elapsedTime();
4127 
4128   G1ParRemoveSelfForwardPtrsTask rsfp_task;
4129   workers()->run_task(&rsfp_task);
4130 
4131   // Now restore saved marks, if any.
4132   for (uint i = 0; i < ParallelGCThreads; i++) {
4133     OopAndMarkOopStack& cur = _preserved_objs[i];
4134     while (!cur.is_empty()) {
4135       OopAndMarkOop elem = cur.pop();
4136       elem.set_mark();
4137     }
4138     cur.clear(true);
4139   }
4140 
4141   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4142 }
4143 
4144 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4145   if (!_evacuation_failed) {
4146     _evacuation_failed = true;
4147   }
4148 
4149   _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4150 
4151   // We want to call the "for_promotion_failure" version only in the
4152   // case of a promotion failure.
4153   if (m->must_be_preserved_for_promotion_failure(obj)) {
4154     OopAndMarkOop elem(obj, m);
4155     _preserved_objs[worker_id].push(elem);
4156   }
4157 }
4158 
4159 class G1ParEvacuateFollowersClosure : public VoidClosure {
4160 private:
4161   double _start_term;
4162   double _term_time;
4163   size_t _term_attempts;
4164 
4165   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4166   void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4167 protected:
4168   G1CollectedHeap*              _g1h;
4169   G1ParScanThreadState*         _par_scan_state;
4170   RefToScanQueueSet*            _queues;
4171   ParallelTaskTerminator*       _terminator;
4172 
4173   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4174   RefToScanQueueSet*      queues()         { return _queues; }
4175   ParallelTaskTerminator* terminator()     { return _terminator; }
4176 
4177 public:
4178   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4179                                 G1ParScanThreadState* par_scan_state,
4180                                 RefToScanQueueSet* queues,
4181                                 ParallelTaskTerminator* terminator)
4182     : _g1h(g1h), _par_scan_state(par_scan_state),
4183       _queues(queues), _terminator(terminator),
4184       _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4185 
4186   void do_void();
4187 
4188   double term_time() const { return _term_time; }
4189   size_t term_attempts() const { return _term_attempts; }
4190 
4191 private:
4192   inline bool offer_termination();
4193 };
4194 
4195 bool G1ParEvacuateFollowersClosure::offer_termination() {
4196   G1ParScanThreadState* const pss = par_scan_state();
4197   start_term_time();
4198   const bool res = terminator()->offer_termination();
4199   end_term_time();
4200   return res;
4201 }
4202 
4203 void G1ParEvacuateFollowersClosure::do_void() {
4204   G1ParScanThreadState* const pss = par_scan_state();
4205   pss->trim_queue();
4206   do {
4207     pss->steal_and_trim_queue(queues());
4208   } while (!offer_termination());
4209 }
4210 
4211 class G1ParTask : public AbstractGangTask {
4212 protected:
4213   G1CollectedHeap*         _g1h;
4214   G1ParScanThreadStateSet* _pss;
4215   RefToScanQueueSet*       _queues;
4216   G1RootProcessor*         _root_processor;
4217   ParallelTaskTerminator   _terminator;
4218   uint                     _n_workers;
4219 
4220 public:
4221   G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4222     : AbstractGangTask("G1 collection"),
4223       _g1h(g1h),
4224       _pss(per_thread_states),
4225       _queues(task_queues),
4226       _root_processor(root_processor),
4227       _terminator(n_workers, _queues),
4228       _n_workers(n_workers)
4229   {}
4230 
4231   void work(uint worker_id) {
4232     if (worker_id >= _n_workers) return;  // no work needed this round
4233 
4234     double start_sec = os::elapsedTime();
4235     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4236 
4237     {
4238       ResourceMark rm;
4239       HandleMark   hm;
4240 
4241       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
4242 
4243       G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
4244       pss->set_ref_processor(rp);
4245 
4246       double start_strong_roots_sec = os::elapsedTime();
4247 
4248       _root_processor->evacuate_roots(pss->closures(), worker_id);
4249 
4250       G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4251 
4252       // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4253       // treating the nmethods visited to act as roots for concurrent marking.
4254       // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4255       // objects copied by the current evacuation.
4256       size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4257                                                                              pss->closures()->weak_codeblobs(),
4258                                                                              worker_id);
4259 
4260       _pss->add_cards_scanned(worker_id, cards_scanned);
4261 
4262       double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4263 
4264       double term_sec = 0.0;
4265       size_t evac_term_attempts = 0;
4266       {
4267         double start = os::elapsedTime();
4268         G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4269         evac.do_void();
4270 
4271         evac_term_attempts = evac.term_attempts();
4272         term_sec = evac.term_time();
4273         double elapsed_sec = os::elapsedTime() - start;
4274         _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4275         _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4276         _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4277       }
4278 
4279       assert(pss->queue_is_empty(), "should be empty");
4280 
4281       if (PrintTerminationStats) {
4282         MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4283         size_t lab_waste;
4284         size_t lab_undo_waste;
4285         pss->waste(lab_waste, lab_undo_waste);
4286         _g1h->print_termination_stats(gclog_or_tty,
4287                                       worker_id,
4288                                       (os::elapsedTime() - start_sec) * 1000.0,   /* elapsed time */
4289                                       strong_roots_sec * 1000.0,                  /* strong roots time */
4290                                       term_sec * 1000.0,                          /* evac term time */
4291                                       evac_term_attempts,                         /* evac term attempts */
4292                                       lab_waste,                                  /* alloc buffer waste */
4293                                       lab_undo_waste                              /* undo waste */
4294                                       );
4295       }
4296 
4297       // Close the inner scope so that the ResourceMark and HandleMark
4298       // destructors are executed here and are included as part of the
4299       // "GC Worker Time".
4300     }
4301     _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4302   }
4303 };
4304 
4305 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4306   st->print_raw_cr("GC Termination Stats");
4307   st->print_raw_cr("     elapsed  --strong roots-- -------termination------- ------waste (KiB)------");
4308   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts  total   alloc    undo");
4309   st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4310 }
4311 
4312 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4313                                               uint worker_id,
4314                                               double elapsed_ms,
4315                                               double strong_roots_ms,
4316                                               double term_ms,
4317                                               size_t term_attempts,
4318                                               size_t alloc_buffer_waste,
4319                                               size_t undo_waste) const {
4320   st->print_cr("%3d %9.2f %9.2f %6.2f "
4321                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4322                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4323                worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4324                term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4325                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4326                alloc_buffer_waste * HeapWordSize / K,
4327                undo_waste * HeapWordSize / K);
4328 }
4329 
4330 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4331 private:
4332   BoolObjectClosure* _is_alive;
4333   int _initial_string_table_size;
4334   int _initial_symbol_table_size;
4335 
4336   bool  _process_strings;
4337   int _strings_processed;
4338   int _strings_removed;
4339 
4340   bool  _process_symbols;
4341   int _symbols_processed;
4342   int _symbols_removed;
4343 
4344 public:
4345   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4346     AbstractGangTask("String/Symbol Unlinking"),
4347     _is_alive(is_alive),
4348     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4349     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4350 
4351     _initial_string_table_size = StringTable::the_table()->table_size();
4352     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4353     if (process_strings) {
4354       StringTable::clear_parallel_claimed_index();
4355     }
4356     if (process_symbols) {
4357       SymbolTable::clear_parallel_claimed_index();
4358     }
4359   }
4360 
4361   ~G1StringSymbolTableUnlinkTask() {
4362     guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4363               "claim value %d after unlink less than initial string table size %d",
4364               StringTable::parallel_claimed_index(), _initial_string_table_size);
4365     guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4366               "claim value %d after unlink less than initial symbol table size %d",
4367               SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4368 
4369     if (G1TraceStringSymbolTableScrubbing) {
4370       gclog_or_tty->print_cr("Cleaned string and symbol table, "
4371                              "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4372                              "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4373                              strings_processed(), strings_removed(),
4374                              symbols_processed(), symbols_removed());
4375     }
4376   }
4377 
4378   void work(uint worker_id) {
4379     int strings_processed = 0;
4380     int strings_removed = 0;
4381     int symbols_processed = 0;
4382     int symbols_removed = 0;
4383     if (_process_strings) {
4384       StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4385       Atomic::add(strings_processed, &_strings_processed);
4386       Atomic::add(strings_removed, &_strings_removed);
4387     }
4388     if (_process_symbols) {
4389       SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4390       Atomic::add(symbols_processed, &_symbols_processed);
4391       Atomic::add(symbols_removed, &_symbols_removed);
4392     }
4393   }
4394 
4395   size_t strings_processed() const { return (size_t)_strings_processed; }
4396   size_t strings_removed()   const { return (size_t)_strings_removed; }
4397 
4398   size_t symbols_processed() const { return (size_t)_symbols_processed; }
4399   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
4400 };
4401 
4402 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4403 private:
4404   static Monitor* _lock;
4405 
4406   BoolObjectClosure* const _is_alive;
4407   const bool               _unloading_occurred;
4408   const uint               _num_workers;
4409 
4410   // Variables used to claim nmethods.
4411   nmethod* _first_nmethod;
4412   volatile nmethod* _claimed_nmethod;
4413 
4414   // The list of nmethods that need to be processed by the second pass.
4415   volatile nmethod* _postponed_list;
4416   volatile uint     _num_entered_barrier;
4417 
4418  public:
4419   G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4420       _is_alive(is_alive),
4421       _unloading_occurred(unloading_occurred),
4422       _num_workers(num_workers),
4423       _first_nmethod(NULL),
4424       _claimed_nmethod(NULL),
4425       _postponed_list(NULL),
4426       _num_entered_barrier(0)
4427   {
4428     nmethod::increase_unloading_clock();
4429     // Get first alive nmethod
4430     NMethodIterator iter = NMethodIterator();
4431     if(iter.next_alive()) {
4432       _first_nmethod = iter.method();
4433     }
4434     _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4435   }
4436 
4437   ~G1CodeCacheUnloadingTask() {
4438     CodeCache::verify_clean_inline_caches();
4439 
4440     CodeCache::set_needs_cache_clean(false);
4441     guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4442 
4443     CodeCache::verify_icholder_relocations();
4444   }
4445 
4446  private:
4447   void add_to_postponed_list(nmethod* nm) {
4448       nmethod* old;
4449       do {
4450         old = (nmethod*)_postponed_list;
4451         nm->set_unloading_next(old);
4452       } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4453   }
4454 
4455   void clean_nmethod(nmethod* nm) {
4456     bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4457 
4458     if (postponed) {
4459       // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4460       add_to_postponed_list(nm);
4461     }
4462 
4463     // Mark that this thread has been cleaned/unloaded.
4464     // After this call, it will be safe to ask if this nmethod was unloaded or not.
4465     nm->set_unloading_clock(nmethod::global_unloading_clock());
4466   }
4467 
4468   void clean_nmethod_postponed(nmethod* nm) {
4469     nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4470   }
4471 
4472   static const int MaxClaimNmethods = 16;
4473 
4474   void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4475     nmethod* first;
4476     NMethodIterator last;
4477 
4478     do {
4479       *num_claimed_nmethods = 0;
4480 
4481       first = (nmethod*)_claimed_nmethod;
4482       last = NMethodIterator(first);
4483 
4484       if (first != NULL) {
4485 
4486         for (int i = 0; i < MaxClaimNmethods; i++) {
4487           if (!last.next_alive()) {
4488             break;
4489           }
4490           claimed_nmethods[i] = last.method();
4491           (*num_claimed_nmethods)++;
4492         }
4493       }
4494 
4495     } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4496   }
4497 
4498   nmethod* claim_postponed_nmethod() {
4499     nmethod* claim;
4500     nmethod* next;
4501 
4502     do {
4503       claim = (nmethod*)_postponed_list;
4504       if (claim == NULL) {
4505         return NULL;
4506       }
4507 
4508       next = claim->unloading_next();
4509 
4510     } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4511 
4512     return claim;
4513   }
4514 
4515  public:
4516   // Mark that we're done with the first pass of nmethod cleaning.
4517   void barrier_mark(uint worker_id) {
4518     MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4519     _num_entered_barrier++;
4520     if (_num_entered_barrier == _num_workers) {
4521       ml.notify_all();
4522     }
4523   }
4524 
4525   // See if we have to wait for the other workers to
4526   // finish their first-pass nmethod cleaning work.
4527   void barrier_wait(uint worker_id) {
4528     if (_num_entered_barrier < _num_workers) {
4529       MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4530       while (_num_entered_barrier < _num_workers) {
4531           ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4532       }
4533     }
4534   }
4535 
4536   // Cleaning and unloading of nmethods. Some work has to be postponed
4537   // to the second pass, when we know which nmethods survive.
4538   void work_first_pass(uint worker_id) {
4539     // The first nmethods is claimed by the first worker.
4540     if (worker_id == 0 && _first_nmethod != NULL) {
4541       clean_nmethod(_first_nmethod);
4542       _first_nmethod = NULL;
4543     }
4544 
4545     int num_claimed_nmethods;
4546     nmethod* claimed_nmethods[MaxClaimNmethods];
4547 
4548     while (true) {
4549       claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4550 
4551       if (num_claimed_nmethods == 0) {
4552         break;
4553       }
4554 
4555       for (int i = 0; i < num_claimed_nmethods; i++) {
4556         clean_nmethod(claimed_nmethods[i]);
4557       }
4558     }
4559   }
4560 
4561   void work_second_pass(uint worker_id) {
4562     nmethod* nm;
4563     // Take care of postponed nmethods.
4564     while ((nm = claim_postponed_nmethod()) != NULL) {
4565       clean_nmethod_postponed(nm);
4566     }
4567   }
4568 };
4569 
4570 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4571 
4572 class G1KlassCleaningTask : public StackObj {
4573   BoolObjectClosure*                      _is_alive;
4574   volatile jint                           _clean_klass_tree_claimed;
4575   ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4576 
4577  public:
4578   G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4579       _is_alive(is_alive),
4580       _clean_klass_tree_claimed(0),
4581       _klass_iterator() {
4582   }
4583 
4584  private:
4585   bool claim_clean_klass_tree_task() {
4586     if (_clean_klass_tree_claimed) {
4587       return false;
4588     }
4589 
4590     return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4591   }
4592 
4593   InstanceKlass* claim_next_klass() {
4594     Klass* klass;
4595     do {
4596       klass =_klass_iterator.next_klass();
4597     } while (klass != NULL && !klass->is_instance_klass());
4598 
4599     // this can be null so don't call InstanceKlass::cast
4600     return static_cast<InstanceKlass*>(klass);
4601   }
4602 
4603 public:
4604 
4605   void clean_klass(InstanceKlass* ik) {
4606     ik->clean_weak_instanceklass_links(_is_alive);
4607   }
4608 
4609   void work() {
4610     ResourceMark rm;
4611 
4612     // One worker will clean the subklass/sibling klass tree.
4613     if (claim_clean_klass_tree_task()) {
4614       Klass::clean_subklass_tree(_is_alive);
4615     }
4616 
4617     // All workers will help cleaning the classes,
4618     InstanceKlass* klass;
4619     while ((klass = claim_next_klass()) != NULL) {
4620       clean_klass(klass);
4621     }
4622   }
4623 };
4624 
4625 // To minimize the remark pause times, the tasks below are done in parallel.
4626 class G1ParallelCleaningTask : public AbstractGangTask {
4627 private:
4628   G1StringSymbolTableUnlinkTask _string_symbol_task;
4629   G1CodeCacheUnloadingTask      _code_cache_task;
4630   G1KlassCleaningTask           _klass_cleaning_task;
4631 
4632 public:
4633   // The constructor is run in the VMThread.
4634   G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4635       AbstractGangTask("Parallel Cleaning"),
4636       _string_symbol_task(is_alive, process_strings, process_symbols),
4637       _code_cache_task(num_workers, is_alive, unloading_occurred),
4638       _klass_cleaning_task(is_alive) {
4639   }
4640 
4641   // The parallel work done by all worker threads.
4642   void work(uint worker_id) {
4643     // Do first pass of code cache cleaning.
4644     _code_cache_task.work_first_pass(worker_id);
4645 
4646     // Let the threads mark that the first pass is done.
4647     _code_cache_task.barrier_mark(worker_id);
4648 
4649     // Clean the Strings and Symbols.
4650     _string_symbol_task.work(worker_id);
4651 
4652     // Wait for all workers to finish the first code cache cleaning pass.
4653     _code_cache_task.barrier_wait(worker_id);
4654 
4655     // Do the second code cache cleaning work, which realize on
4656     // the liveness information gathered during the first pass.
4657     _code_cache_task.work_second_pass(worker_id);
4658 
4659     // Clean all klasses that were not unloaded.
4660     _klass_cleaning_task.work();
4661   }
4662 };
4663 
4664 
4665 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4666                                         bool process_strings,
4667                                         bool process_symbols,
4668                                         bool class_unloading_occurred) {
4669   uint n_workers = workers()->active_workers();
4670 
4671   G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4672                                         n_workers, class_unloading_occurred);
4673   workers()->run_task(&g1_unlink_task);
4674 }
4675 
4676 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4677                                                      bool process_strings, bool process_symbols) {
4678   {
4679     G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4680     workers()->run_task(&g1_unlink_task);
4681   }
4682 
4683   if (G1StringDedup::is_enabled()) {
4684     G1StringDedup::unlink(is_alive);
4685   }
4686 }
4687 
4688 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4689  private:
4690   DirtyCardQueueSet* _queue;
4691  public:
4692   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4693 
4694   virtual void work(uint worker_id) {
4695     G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4696     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4697 
4698     RedirtyLoggedCardTableEntryClosure cl;
4699     _queue->par_apply_closure_to_all_completed_buffers(&cl);
4700 
4701     phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4702   }
4703 };
4704 
4705 void G1CollectedHeap::redirty_logged_cards() {
4706   double redirty_logged_cards_start = os::elapsedTime();
4707 
4708   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4709   dirty_card_queue_set().reset_for_par_iteration();
4710   workers()->run_task(&redirty_task);
4711 
4712   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4713   dcq.merge_bufferlists(&dirty_card_queue_set());
4714   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4715 
4716   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4717 }
4718 
4719 // Weak Reference Processing support
4720 
4721 // An always "is_alive" closure that is used to preserve referents.
4722 // If the object is non-null then it's alive.  Used in the preservation
4723 // of referent objects that are pointed to by reference objects
4724 // discovered by the CM ref processor.
4725 class G1AlwaysAliveClosure: public BoolObjectClosure {
4726   G1CollectedHeap* _g1;
4727 public:
4728   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4729   bool do_object_b(oop p) {
4730     if (p != NULL) {
4731       return true;
4732     }
4733     return false;
4734   }
4735 };
4736 
4737 bool G1STWIsAliveClosure::do_object_b(oop p) {
4738   // An object is reachable if it is outside the collection set,
4739   // or is inside and copied.
4740   return !_g1->is_in_cset(p) || p->is_forwarded();
4741 }
4742 
4743 // Non Copying Keep Alive closure
4744 class G1KeepAliveClosure: public OopClosure {
4745   G1CollectedHeap* _g1;
4746 public:
4747   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4748   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4749   void do_oop(oop* p) {
4750     oop obj = *p;
4751     assert(obj != NULL, "the caller should have filtered out NULL values");
4752 
4753     const InCSetState cset_state = _g1->in_cset_state(obj);
4754     if (!cset_state.is_in_cset_or_humongous()) {
4755       return;
4756     }
4757     if (cset_state.is_in_cset()) {
4758       assert( obj->is_forwarded(), "invariant" );
4759       *p = obj->forwardee();
4760     } else {
4761       assert(!obj->is_forwarded(), "invariant" );
4762       assert(cset_state.is_humongous(),
4763              "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4764       _g1->set_humongous_is_live(obj);
4765     }
4766   }
4767 };
4768 
4769 // Copying Keep Alive closure - can be called from both
4770 // serial and parallel code as long as different worker
4771 // threads utilize different G1ParScanThreadState instances
4772 // and different queues.
4773 
4774 class G1CopyingKeepAliveClosure: public OopClosure {
4775   G1CollectedHeap*         _g1h;
4776   OopClosure*              _copy_non_heap_obj_cl;
4777   G1ParScanThreadState*    _par_scan_state;
4778 
4779 public:
4780   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4781                             OopClosure* non_heap_obj_cl,
4782                             G1ParScanThreadState* pss):
4783     _g1h(g1h),
4784     _copy_non_heap_obj_cl(non_heap_obj_cl),
4785     _par_scan_state(pss)
4786   {}
4787 
4788   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4789   virtual void do_oop(      oop* p) { do_oop_work(p); }
4790 
4791   template <class T> void do_oop_work(T* p) {
4792     oop obj = oopDesc::load_decode_heap_oop(p);
4793 
4794     if (_g1h->is_in_cset_or_humongous(obj)) {
4795       // If the referent object has been forwarded (either copied
4796       // to a new location or to itself in the event of an
4797       // evacuation failure) then we need to update the reference
4798       // field and, if both reference and referent are in the G1
4799       // heap, update the RSet for the referent.
4800       //
4801       // If the referent has not been forwarded then we have to keep
4802       // it alive by policy. Therefore we have copy the referent.
4803       //
4804       // If the reference field is in the G1 heap then we can push
4805       // on the PSS queue. When the queue is drained (after each
4806       // phase of reference processing) the object and it's followers
4807       // will be copied, the reference field set to point to the
4808       // new location, and the RSet updated. Otherwise we need to
4809       // use the the non-heap or metadata closures directly to copy
4810       // the referent object and update the pointer, while avoiding
4811       // updating the RSet.
4812 
4813       if (_g1h->is_in_g1_reserved(p)) {
4814         _par_scan_state->push_on_queue(p);
4815       } else {
4816         assert(!Metaspace::contains((const void*)p),
4817                "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4818         _copy_non_heap_obj_cl->do_oop(p);
4819       }
4820     }
4821   }
4822 };
4823 
4824 // Serial drain queue closure. Called as the 'complete_gc'
4825 // closure for each discovered list in some of the
4826 // reference processing phases.
4827 
4828 class G1STWDrainQueueClosure: public VoidClosure {
4829 protected:
4830   G1CollectedHeap* _g1h;
4831   G1ParScanThreadState* _par_scan_state;
4832 
4833   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4834 
4835 public:
4836   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4837     _g1h(g1h),
4838     _par_scan_state(pss)
4839   { }
4840 
4841   void do_void() {
4842     G1ParScanThreadState* const pss = par_scan_state();
4843     pss->trim_queue();
4844   }
4845 };
4846 
4847 // Parallel Reference Processing closures
4848 
4849 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4850 // processing during G1 evacuation pauses.
4851 
4852 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4853 private:
4854   G1CollectedHeap*          _g1h;
4855   G1ParScanThreadStateSet*  _pss;
4856   RefToScanQueueSet*        _queues;
4857   WorkGang*                 _workers;
4858   uint                      _active_workers;
4859 
4860 public:
4861   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4862                            G1ParScanThreadStateSet* per_thread_states,
4863                            WorkGang* workers,
4864                            RefToScanQueueSet *task_queues,
4865                            uint n_workers) :
4866     _g1h(g1h),
4867     _pss(per_thread_states),
4868     _queues(task_queues),
4869     _workers(workers),
4870     _active_workers(n_workers)
4871   {
4872     assert(n_workers > 0, "shouldn't call this otherwise");
4873   }
4874 
4875   // Executes the given task using concurrent marking worker threads.
4876   virtual void execute(ProcessTask& task);
4877   virtual void execute(EnqueueTask& task);
4878 };
4879 
4880 // Gang task for possibly parallel reference processing
4881 
4882 class G1STWRefProcTaskProxy: public AbstractGangTask {
4883   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4884   ProcessTask&     _proc_task;
4885   G1CollectedHeap* _g1h;
4886   G1ParScanThreadStateSet* _pss;
4887   RefToScanQueueSet* _task_queues;
4888   ParallelTaskTerminator* _terminator;
4889 
4890 public:
4891   G1STWRefProcTaskProxy(ProcessTask& proc_task,
4892                         G1CollectedHeap* g1h,
4893                         G1ParScanThreadStateSet* per_thread_states,
4894                         RefToScanQueueSet *task_queues,
4895                         ParallelTaskTerminator* terminator) :
4896     AbstractGangTask("Process reference objects in parallel"),
4897     _proc_task(proc_task),
4898     _g1h(g1h),
4899     _pss(per_thread_states),
4900     _task_queues(task_queues),
4901     _terminator(terminator)
4902   {}
4903 
4904   virtual void work(uint worker_id) {
4905     // The reference processing task executed by a single worker.
4906     ResourceMark rm;
4907     HandleMark   hm;
4908 
4909     G1STWIsAliveClosure is_alive(_g1h);
4910 
4911     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
4912     pss->set_ref_processor(NULL);
4913 
4914     // Keep alive closure.
4915     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4916 
4917     // Complete GC closure
4918     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4919 
4920     // Call the reference processing task's work routine.
4921     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4922 
4923     // Note we cannot assert that the refs array is empty here as not all
4924     // of the processing tasks (specifically phase2 - pp2_work) execute
4925     // the complete_gc closure (which ordinarily would drain the queue) so
4926     // the queue may not be empty.
4927   }
4928 };
4929 
4930 // Driver routine for parallel reference processing.
4931 // Creates an instance of the ref processing gang
4932 // task and has the worker threads execute it.
4933 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4934   assert(_workers != NULL, "Need parallel worker threads.");
4935 
4936   ParallelTaskTerminator terminator(_active_workers, _queues);
4937   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4938 
4939   _workers->run_task(&proc_task_proxy);
4940 }
4941 
4942 // Gang task for parallel reference enqueueing.
4943 
4944 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4945   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4946   EnqueueTask& _enq_task;
4947 
4948 public:
4949   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4950     AbstractGangTask("Enqueue reference objects in parallel"),
4951     _enq_task(enq_task)
4952   { }
4953 
4954   virtual void work(uint worker_id) {
4955     _enq_task.work(worker_id);
4956   }
4957 };
4958 
4959 // Driver routine for parallel reference enqueueing.
4960 // Creates an instance of the ref enqueueing gang
4961 // task and has the worker threads execute it.
4962 
4963 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4964   assert(_workers != NULL, "Need parallel worker threads.");
4965 
4966   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4967 
4968   _workers->run_task(&enq_task_proxy);
4969 }
4970 
4971 // End of weak reference support closures
4972 
4973 // Abstract task used to preserve (i.e. copy) any referent objects
4974 // that are in the collection set and are pointed to by reference
4975 // objects discovered by the CM ref processor.
4976 
4977 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4978 protected:
4979   G1CollectedHeap*         _g1h;
4980   G1ParScanThreadStateSet* _pss;
4981   RefToScanQueueSet*       _queues;
4982   ParallelTaskTerminator   _terminator;
4983   uint                     _n_workers;
4984 
4985 public:
4986   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4987     AbstractGangTask("ParPreserveCMReferents"),
4988     _g1h(g1h),
4989     _pss(per_thread_states),
4990     _queues(task_queues),
4991     _terminator(workers, _queues),
4992     _n_workers(workers)
4993   { }
4994 
4995   void work(uint worker_id) {
4996     ResourceMark rm;
4997     HandleMark   hm;
4998 
4999     G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
5000     pss->set_ref_processor(NULL);
5001     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5002 
5003     // Is alive closure
5004     G1AlwaysAliveClosure always_alive(_g1h);
5005 
5006     // Copying keep alive closure. Applied to referent objects that need
5007     // to be copied.
5008     G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
5009 
5010     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5011 
5012     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5013     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5014 
5015     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5016     // So this must be true - but assert just in case someone decides to
5017     // change the worker ids.
5018     assert(worker_id < limit, "sanity");
5019     assert(!rp->discovery_is_atomic(), "check this code");
5020 
5021     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5022     for (uint idx = worker_id; idx < limit; idx += stride) {
5023       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5024 
5025       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5026       while (iter.has_next()) {
5027         // Since discovery is not atomic for the CM ref processor, we
5028         // can see some null referent objects.
5029         iter.load_ptrs(DEBUG_ONLY(true));
5030         oop ref = iter.obj();
5031 
5032         // This will filter nulls.
5033         if (iter.is_referent_alive()) {
5034           iter.make_referent_alive();
5035         }
5036         iter.move_to_next();
5037       }
5038     }
5039 
5040     // Drain the queue - which may cause stealing
5041     G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5042     drain_queue.do_void();
5043     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5044     assert(pss->queue_is_empty(), "should be");
5045   }
5046 };
5047 
5048 // Weak Reference processing during an evacuation pause (part 1).
5049 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5050   double ref_proc_start = os::elapsedTime();
5051 
5052   ReferenceProcessor* rp = _ref_processor_stw;
5053   assert(rp->discovery_enabled(), "should have been enabled");
5054 
5055   // Any reference objects, in the collection set, that were 'discovered'
5056   // by the CM ref processor should have already been copied (either by
5057   // applying the external root copy closure to the discovered lists, or
5058   // by following an RSet entry).
5059   //
5060   // But some of the referents, that are in the collection set, that these
5061   // reference objects point to may not have been copied: the STW ref
5062   // processor would have seen that the reference object had already
5063   // been 'discovered' and would have skipped discovering the reference,
5064   // but would not have treated the reference object as a regular oop.
5065   // As a result the copy closure would not have been applied to the
5066   // referent object.
5067   //
5068   // We need to explicitly copy these referent objects - the references
5069   // will be processed at the end of remarking.
5070   //
5071   // We also need to do this copying before we process the reference
5072   // objects discovered by the STW ref processor in case one of these
5073   // referents points to another object which is also referenced by an
5074   // object discovered by the STW ref processor.
5075 
5076   uint no_of_gc_workers = workers()->active_workers();
5077 
5078   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5079                                                  per_thread_states,
5080                                                  no_of_gc_workers,
5081                                                  _task_queues);
5082 
5083   workers()->run_task(&keep_cm_referents);
5084 
5085   // Closure to test whether a referent is alive.
5086   G1STWIsAliveClosure is_alive(this);
5087 
5088   // Even when parallel reference processing is enabled, the processing
5089   // of JNI refs is serial and performed serially by the current thread
5090   // rather than by a worker. The following PSS will be used for processing
5091   // JNI refs.
5092 
5093   // Use only a single queue for this PSS.
5094   G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
5095   pss->set_ref_processor(NULL);
5096   assert(pss->queue_is_empty(), "pre-condition");
5097 
5098   // Keep alive closure.
5099   G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5100 
5101   // Serial Complete GC closure
5102   G1STWDrainQueueClosure drain_queue(this, pss);
5103 
5104   // Setup the soft refs policy...
5105   rp->setup_policy(false);
5106 
5107   ReferenceProcessorStats stats;
5108   if (!rp->processing_is_mt()) {
5109     // Serial reference processing...
5110     stats = rp->process_discovered_references(&is_alive,
5111                                               &keep_alive,
5112                                               &drain_queue,
5113                                               NULL,
5114                                               _gc_timer_stw);
5115   } else {
5116     // Parallel reference processing
5117     assert(rp->num_q() == no_of_gc_workers, "sanity");
5118     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5119 
5120     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5121     stats = rp->process_discovered_references(&is_alive,
5122                                               &keep_alive,
5123                                               &drain_queue,
5124                                               &par_task_executor,
5125                                               _gc_timer_stw);
5126   }
5127 
5128   _gc_tracer_stw->report_gc_reference_stats(stats);
5129 
5130   // We have completed copying any necessary live referent objects.
5131   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5132 
5133   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5134   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5135 }
5136 
5137 // Weak Reference processing during an evacuation pause (part 2).
5138 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5139   double ref_enq_start = os::elapsedTime();
5140 
5141   ReferenceProcessor* rp = _ref_processor_stw;
5142   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5143 
5144   // Now enqueue any remaining on the discovered lists on to
5145   // the pending list.
5146   if (!rp->processing_is_mt()) {
5147     // Serial reference processing...
5148     rp->enqueue_discovered_references();
5149   } else {
5150     // Parallel reference enqueueing
5151 
5152     uint n_workers = workers()->active_workers();
5153 
5154     assert(rp->num_q() == n_workers, "sanity");
5155     assert(n_workers <= rp->max_num_q(), "sanity");
5156 
5157     G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5158     rp->enqueue_discovered_references(&par_task_executor);
5159   }
5160 
5161   rp->verify_no_references_recorded();
5162   assert(!rp->discovery_enabled(), "should have been disabled");
5163 
5164   // FIXME
5165   // CM's reference processing also cleans up the string and symbol tables.
5166   // Should we do that here also? We could, but it is a serial operation
5167   // and could significantly increase the pause time.
5168 
5169   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5170   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5171 }
5172 
5173 void G1CollectedHeap::pre_evacuate_collection_set() {
5174   _expand_heap_after_alloc_failure = true;
5175   _evacuation_failed = false;
5176 
5177   // Disable the hot card cache.
5178   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5179   hot_card_cache->reset_hot_cache_claimed_index();
5180   hot_card_cache->set_use_cache(false);
5181 
5182 }
5183 
5184 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5185   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5186 
5187   // Should G1EvacuationFailureALot be in effect for this GC?
5188   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5189 
5190   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5191   double start_par_time_sec = os::elapsedTime();
5192   double end_par_time_sec;
5193 
5194   {
5195     const uint n_workers = workers()->active_workers();
5196     G1RootProcessor root_processor(this, n_workers);
5197     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5198     // InitialMark needs claim bits to keep track of the marked-through CLDs.
5199     if (collector_state()->during_initial_mark_pause()) {
5200       ClassLoaderDataGraph::clear_claimed_marks();
5201     }
5202 
5203     // The individual threads will set their evac-failure closures.
5204     if (PrintTerminationStats) {
5205       print_termination_stats_hdr(gclog_or_tty);
5206     }
5207 
5208     workers()->run_task(&g1_par_task);
5209     end_par_time_sec = os::elapsedTime();
5210 
5211     // Closing the inner scope will execute the destructor
5212     // for the G1RootProcessor object. We record the current
5213     // elapsed time before closing the scope so that time
5214     // taken for the destructor is NOT included in the
5215     // reported parallel time.
5216   }
5217 
5218   G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5219 
5220   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5221   phase_times->record_par_time(par_time_ms);
5222 
5223   double code_root_fixup_time_ms =
5224         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5225   phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5226 
5227   // Process any discovered reference objects - we have
5228   // to do this _before_ we retire the GC alloc regions
5229   // as we may have to copy some 'reachable' referent
5230   // objects (and their reachable sub-graphs) that were
5231   // not copied during the pause.
5232   process_discovered_references(per_thread_states);
5233 
5234   if (G1StringDedup::is_enabled()) {
5235     double fixup_start = os::elapsedTime();
5236 
5237     G1STWIsAliveClosure is_alive(this);
5238     G1KeepAliveClosure keep_alive(this);
5239     G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5240 
5241     double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5242     phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5243   }
5244 
5245   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5246 
5247   if (evacuation_failed()) {
5248     remove_self_forwarding_pointers();
5249 
5250     // Reset the G1EvacuationFailureALot counters and flags
5251     // Note: the values are reset only when an actual
5252     // evacuation failure occurs.
5253     NOT_PRODUCT(reset_evacuation_should_fail();)
5254   }
5255 
5256   // Enqueue any remaining references remaining on the STW
5257   // reference processor's discovered lists. We need to do
5258   // this after the card table is cleaned (and verified) as
5259   // the act of enqueueing entries on to the pending list
5260   // will log these updates (and dirty their associated
5261   // cards). We need these updates logged to update any
5262   // RSets.
5263   enqueue_discovered_references(per_thread_states);
5264 }
5265 
5266 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5267   _allocator->release_gc_alloc_regions(evacuation_info);
5268 
5269   per_thread_states->flush();
5270 
5271   record_obj_copy_mem_stats();
5272 
5273   // Reset and re-enable the hot card cache.
5274   // Note the counts for the cards in the regions in the
5275   // collection set are reset when the collection set is freed.
5276   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5277   hot_card_cache->reset_hot_cache();
5278   hot_card_cache->set_use_cache(true);
5279 
5280   purge_code_root_memory();
5281 
5282   redirty_logged_cards();
5283 #if defined(COMPILER2) || INCLUDE_JVMCI
5284   DerivedPointerTable::update_pointers();
5285 #endif
5286 }
5287 
5288 void G1CollectedHeap::record_obj_copy_mem_stats() {
5289   _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5290                                                create_g1_evac_summary(&_old_evac_stats));
5291 }
5292 
5293 void G1CollectedHeap::free_region(HeapRegion* hr,
5294                                   FreeRegionList* free_list,
5295                                   bool par,
5296                                   bool locked) {
5297   assert(!hr->is_free(), "the region should not be free");
5298   assert(!hr->is_empty(), "the region should not be empty");
5299   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5300   assert(free_list != NULL, "pre-condition");
5301 
5302   if (G1VerifyBitmaps) {
5303     MemRegion mr(hr->bottom(), hr->end());
5304     concurrent_mark()->clearRangePrevBitmap(mr);
5305   }
5306 
5307   // Clear the card counts for this region.
5308   // Note: we only need to do this if the region is not young
5309   // (since we don't refine cards in young regions).
5310   if (!hr->is_young()) {
5311     _cg1r->hot_card_cache()->reset_card_counts(hr);
5312   }
5313   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5314   free_list->add_ordered(hr);
5315 }
5316 
5317 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5318                                      FreeRegionList* free_list,
5319                                      bool par) {
5320   assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5321   assert(free_list != NULL, "pre-condition");
5322 
5323   size_t hr_capacity = hr->capacity();
5324   // We need to read this before we make the region non-humongous,
5325   // otherwise the information will be gone.
5326   uint last_index = hr->last_hc_index();
5327   hr->clear_humongous();
5328   free_region(hr, free_list, par);
5329 
5330   uint i = hr->hrm_index() + 1;
5331   while (i < last_index) {
5332     HeapRegion* curr_hr = region_at(i);
5333     assert(curr_hr->is_continues_humongous(), "invariant");
5334     curr_hr->clear_humongous();
5335     free_region(curr_hr, free_list, par);
5336     i += 1;
5337   }
5338 }
5339 
5340 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5341                                        const HeapRegionSetCount& humongous_regions_removed) {
5342   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5343     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5344     _old_set.bulk_remove(old_regions_removed);
5345     _humongous_set.bulk_remove(humongous_regions_removed);
5346   }
5347 
5348 }
5349 
5350 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5351   assert(list != NULL, "list can't be null");
5352   if (!list->is_empty()) {
5353     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5354     _hrm.insert_list_into_free_list(list);
5355   }
5356 }
5357 
5358 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5359   decrease_used(bytes);
5360 }
5361 
5362 class G1ParCleanupCTTask : public AbstractGangTask {
5363   G1SATBCardTableModRefBS* _ct_bs;
5364   G1CollectedHeap* _g1h;
5365   HeapRegion* volatile _su_head;
5366 public:
5367   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5368                      G1CollectedHeap* g1h) :
5369     AbstractGangTask("G1 Par Cleanup CT Task"),
5370     _ct_bs(ct_bs), _g1h(g1h) { }
5371 
5372   void work(uint worker_id) {
5373     HeapRegion* r;
5374     while (r = _g1h->pop_dirty_cards_region()) {
5375       clear_cards(r);
5376     }
5377   }
5378 
5379   void clear_cards(HeapRegion* r) {
5380     // Cards of the survivors should have already been dirtied.
5381     if (!r->is_survivor()) {
5382       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5383     }
5384   }
5385 };
5386 
5387 #ifndef PRODUCT
5388 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5389   G1CollectedHeap* _g1h;
5390   G1SATBCardTableModRefBS* _ct_bs;
5391 public:
5392   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5393     : _g1h(g1h), _ct_bs(ct_bs) { }
5394   virtual bool doHeapRegion(HeapRegion* r) {
5395     if (r->is_survivor()) {
5396       _g1h->verify_dirty_region(r);
5397     } else {
5398       _g1h->verify_not_dirty_region(r);
5399     }
5400     return false;
5401   }
5402 };
5403 
5404 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5405   // All of the region should be clean.
5406   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5407   MemRegion mr(hr->bottom(), hr->end());
5408   ct_bs->verify_not_dirty_region(mr);
5409 }
5410 
5411 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5412   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
5413   // dirty allocated blocks as they allocate them. The thread that
5414   // retires each region and replaces it with a new one will do a
5415   // maximal allocation to fill in [pre_dummy_top(),end()] but will
5416   // not dirty that area (one less thing to have to do while holding
5417   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5418   // is dirty.
5419   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5420   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5421   if (hr->is_young()) {
5422     ct_bs->verify_g1_young_region(mr);
5423   } else {
5424     ct_bs->verify_dirty_region(mr);
5425   }
5426 }
5427 
5428 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5429   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5430   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5431     verify_dirty_region(hr);
5432   }
5433 }
5434 
5435 void G1CollectedHeap::verify_dirty_young_regions() {
5436   verify_dirty_young_list(_young_list->first_region());
5437 }
5438 
5439 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5440                                                HeapWord* tams, HeapWord* end) {
5441   guarantee(tams <= end,
5442             "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5443   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5444   if (result < end) {
5445     gclog_or_tty->cr();
5446     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5447                            bitmap_name, p2i(result));
5448     gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5449                            bitmap_name, p2i(tams), p2i(end));
5450     return false;
5451   }
5452   return true;
5453 }
5454 
5455 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5456   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5457   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5458 
5459   HeapWord* bottom = hr->bottom();
5460   HeapWord* ptams  = hr->prev_top_at_mark_start();
5461   HeapWord* ntams  = hr->next_top_at_mark_start();
5462   HeapWord* end    = hr->end();
5463 
5464   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5465 
5466   bool res_n = true;
5467   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5468   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5469   // if we happen to be in that state.
5470   if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5471     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5472   }
5473   if (!res_p || !res_n) {
5474     gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5475                            HR_FORMAT_PARAMS(hr));
5476     gclog_or_tty->print_cr("#### Caller: %s", caller);
5477     return false;
5478   }
5479   return true;
5480 }
5481 
5482 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5483   if (!G1VerifyBitmaps) return;
5484 
5485   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5486 }
5487 
5488 class G1VerifyBitmapClosure : public HeapRegionClosure {
5489 private:
5490   const char* _caller;
5491   G1CollectedHeap* _g1h;
5492   bool _failures;
5493 
5494 public:
5495   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5496     _caller(caller), _g1h(g1h), _failures(false) { }
5497 
5498   bool failures() { return _failures; }
5499 
5500   virtual bool doHeapRegion(HeapRegion* hr) {
5501     if (hr->is_continues_humongous()) return false;
5502 
5503     bool result = _g1h->verify_bitmaps(_caller, hr);
5504     if (!result) {
5505       _failures = true;
5506     }
5507     return false;
5508   }
5509 };
5510 
5511 void G1CollectedHeap::check_bitmaps(const char* caller) {
5512   if (!G1VerifyBitmaps) return;
5513 
5514   G1VerifyBitmapClosure cl(caller, this);
5515   heap_region_iterate(&cl);
5516   guarantee(!cl.failures(), "bitmap verification");
5517 }
5518 
5519 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5520  private:
5521   bool _failures;
5522  public:
5523   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5524 
5525   virtual bool doHeapRegion(HeapRegion* hr) {
5526     uint i = hr->hrm_index();
5527     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5528     if (hr->is_humongous()) {
5529       if (hr->in_collection_set()) {
5530         gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5531         _failures = true;
5532         return true;
5533       }
5534       if (cset_state.is_in_cset()) {
5535         gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5536         _failures = true;
5537         return true;
5538       }
5539       if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5540         gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5541         _failures = true;
5542         return true;
5543       }
5544     } else {
5545       if (cset_state.is_humongous()) {
5546         gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5547         _failures = true;
5548         return true;
5549       }
5550       if (hr->in_collection_set() != cset_state.is_in_cset()) {
5551         gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5552                                hr->in_collection_set(), cset_state.value(), i);
5553         _failures = true;
5554         return true;
5555       }
5556       if (cset_state.is_in_cset()) {
5557         if (hr->is_young() != (cset_state.is_young())) {
5558           gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5559                                  hr->is_young(), cset_state.value(), i);
5560           _failures = true;
5561           return true;
5562         }
5563         if (hr->is_old() != (cset_state.is_old())) {
5564           gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5565                                  hr->is_old(), cset_state.value(), i);
5566           _failures = true;
5567           return true;
5568         }
5569       }
5570     }
5571     return false;
5572   }
5573 
5574   bool failures() const { return _failures; }
5575 };
5576 
5577 bool G1CollectedHeap::check_cset_fast_test() {
5578   G1CheckCSetFastTableClosure cl;
5579   _hrm.iterate(&cl);
5580   return !cl.failures();
5581 }
5582 #endif // PRODUCT
5583 
5584 void G1CollectedHeap::cleanUpCardTable() {
5585   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5586   double start = os::elapsedTime();
5587 
5588   {
5589     // Iterate over the dirty cards region list.
5590     G1ParCleanupCTTask cleanup_task(ct_bs, this);
5591 
5592     workers()->run_task(&cleanup_task);
5593 #ifndef PRODUCT
5594     if (G1VerifyCTCleanup || VerifyAfterGC) {
5595       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5596       heap_region_iterate(&cleanup_verifier);
5597     }
5598 #endif
5599   }
5600 
5601   double elapsed = os::elapsedTime() - start;
5602   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5603 }
5604 
5605 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5606   size_t pre_used = 0;
5607   FreeRegionList local_free_list("Local List for CSet Freeing");
5608 
5609   double young_time_ms     = 0.0;
5610   double non_young_time_ms = 0.0;
5611 
5612   // Since the collection set is a superset of the the young list,
5613   // all we need to do to clear the young list is clear its
5614   // head and length, and unlink any young regions in the code below
5615   _young_list->clear();
5616 
5617   G1CollectorPolicy* policy = g1_policy();
5618 
5619   double start_sec = os::elapsedTime();
5620   bool non_young = true;
5621 
5622   HeapRegion* cur = cs_head;
5623   int age_bound = -1;
5624   size_t rs_lengths = 0;
5625 
5626   while (cur != NULL) {
5627     assert(!is_on_master_free_list(cur), "sanity");
5628     if (non_young) {
5629       if (cur->is_young()) {
5630         double end_sec = os::elapsedTime();
5631         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5632         non_young_time_ms += elapsed_ms;
5633 
5634         start_sec = os::elapsedTime();
5635         non_young = false;
5636       }
5637     } else {
5638       if (!cur->is_young()) {
5639         double end_sec = os::elapsedTime();
5640         double elapsed_ms = (end_sec - start_sec) * 1000.0;
5641         young_time_ms += elapsed_ms;
5642 
5643         start_sec = os::elapsedTime();
5644         non_young = true;
5645       }
5646     }
5647 
5648     rs_lengths += cur->rem_set()->occupied_locked();
5649 
5650     HeapRegion* next = cur->next_in_collection_set();
5651     assert(cur->in_collection_set(), "bad CS");
5652     cur->set_next_in_collection_set(NULL);
5653     clear_in_cset(cur);
5654 
5655     if (cur->is_young()) {
5656       int index = cur->young_index_in_cset();
5657       assert(index != -1, "invariant");
5658       assert((uint) index < policy->young_cset_region_length(), "invariant");
5659       size_t words_survived = surviving_young_words[index];
5660       cur->record_surv_words_in_group(words_survived);
5661 
5662       // At this point the we have 'popped' cur from the collection set
5663       // (linked via next_in_collection_set()) but it is still in the
5664       // young list (linked via next_young_region()). Clear the
5665       // _next_young_region field.
5666       cur->set_next_young_region(NULL);
5667     } else {
5668       int index = cur->young_index_in_cset();
5669       assert(index == -1, "invariant");
5670     }
5671 
5672     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5673             (!cur->is_young() && cur->young_index_in_cset() == -1),
5674             "invariant" );
5675 
5676     if (!cur->evacuation_failed()) {
5677       MemRegion used_mr = cur->used_region();
5678 
5679       // And the region is empty.
5680       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5681       pre_used += cur->used();
5682       free_region(cur, &local_free_list, false /* par */, true /* locked */);
5683     } else {
5684       cur->uninstall_surv_rate_group();
5685       if (cur->is_young()) {
5686         cur->set_young_index_in_cset(-1);
5687       }
5688       cur->set_evacuation_failed(false);
5689       // The region is now considered to be old.
5690       cur->set_old();
5691       // Do some allocation statistics accounting. Regions that failed evacuation
5692       // are always made old, so there is no need to update anything in the young
5693       // gen statistics, but we need to update old gen statistics.
5694       size_t used_words = cur->marked_bytes() / HeapWordSize;
5695       _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5696       _old_set.add(cur);
5697       evacuation_info.increment_collectionset_used_after(cur->used());
5698     }
5699     cur = next;
5700   }
5701 
5702   evacuation_info.set_regions_freed(local_free_list.length());
5703   policy->record_max_rs_lengths(rs_lengths);
5704   policy->cset_regions_freed();
5705 
5706   double end_sec = os::elapsedTime();
5707   double elapsed_ms = (end_sec - start_sec) * 1000.0;
5708 
5709   if (non_young) {
5710     non_young_time_ms += elapsed_ms;
5711   } else {
5712     young_time_ms += elapsed_ms;
5713   }
5714 
5715   prepend_to_freelist(&local_free_list);
5716   decrement_summary_bytes(pre_used);
5717   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5718   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5719 }
5720 
5721 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5722  private:
5723   FreeRegionList* _free_region_list;
5724   HeapRegionSet* _proxy_set;
5725   HeapRegionSetCount _humongous_regions_removed;
5726   size_t _freed_bytes;
5727  public:
5728 
5729   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5730     _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5731   }
5732 
5733   virtual bool doHeapRegion(HeapRegion* r) {
5734     if (!r->is_starts_humongous()) {
5735       return false;
5736     }
5737 
5738     G1CollectedHeap* g1h = G1CollectedHeap::heap();
5739 
5740     oop obj = (oop)r->bottom();
5741     CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5742 
5743     // The following checks whether the humongous object is live are sufficient.
5744     // The main additional check (in addition to having a reference from the roots
5745     // or the young gen) is whether the humongous object has a remembered set entry.
5746     //
5747     // A humongous object cannot be live if there is no remembered set for it
5748     // because:
5749     // - there can be no references from within humongous starts regions referencing
5750     // the object because we never allocate other objects into them.
5751     // (I.e. there are no intra-region references that may be missed by the
5752     // remembered set)
5753     // - as soon there is a remembered set entry to the humongous starts region
5754     // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5755     // until the end of a concurrent mark.
5756     //
5757     // It is not required to check whether the object has been found dead by marking
5758     // or not, in fact it would prevent reclamation within a concurrent cycle, as
5759     // all objects allocated during that time are considered live.
5760     // SATB marking is even more conservative than the remembered set.
5761     // So if at this point in the collection there is no remembered set entry,
5762     // nobody has a reference to it.
5763     // At the start of collection we flush all refinement logs, and remembered sets
5764     // are completely up-to-date wrt to references to the humongous object.
5765     //
5766     // Other implementation considerations:
5767     // - never consider object arrays at this time because they would pose
5768     // considerable effort for cleaning up the the remembered sets. This is
5769     // required because stale remembered sets might reference locations that
5770     // are currently allocated into.
5771     uint region_idx = r->hrm_index();
5772     if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5773         !r->rem_set()->is_empty()) {
5774 
5775       if (G1TraceEagerReclaimHumongousObjects) {
5776         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",
5777                                region_idx,
5778                                (size_t)obj->size() * HeapWordSize,
5779                                p2i(r->bottom()),
5780                                r->region_num(),
5781                                r->rem_set()->occupied(),
5782                                r->rem_set()->strong_code_roots_list_length(),
5783                                next_bitmap->isMarked(r->bottom()),
5784                                g1h->is_humongous_reclaim_candidate(region_idx),
5785                                obj->is_typeArray()
5786                               );
5787       }
5788 
5789       return false;
5790     }
5791 
5792     guarantee(obj->is_typeArray(),
5793               "Only eagerly reclaiming type arrays is supported, but the object "
5794               PTR_FORMAT " is not.", p2i(r->bottom()));
5795 
5796     if (G1TraceEagerReclaimHumongousObjects) {
5797       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",
5798                              region_idx,
5799                              (size_t)obj->size() * HeapWordSize,
5800                              p2i(r->bottom()),
5801                              r->region_num(),
5802                              r->rem_set()->occupied(),
5803                              r->rem_set()->strong_code_roots_list_length(),
5804                              next_bitmap->isMarked(r->bottom()),
5805                              g1h->is_humongous_reclaim_candidate(region_idx),
5806                              obj->is_typeArray()
5807                             );
5808     }
5809     // Need to clear mark bit of the humongous object if already set.
5810     if (next_bitmap->isMarked(r->bottom())) {
5811       next_bitmap->clear(r->bottom());
5812     }
5813     _freed_bytes += r->used();
5814     r->set_containing_set(NULL);
5815     _humongous_regions_removed.increment(1u, r->capacity());
5816     g1h->free_humongous_region(r, _free_region_list, false);
5817 
5818     return false;
5819   }
5820 
5821   HeapRegionSetCount& humongous_free_count() {
5822     return _humongous_regions_removed;
5823   }
5824 
5825   size_t bytes_freed() const {
5826     return _freed_bytes;
5827   }
5828 
5829   size_t humongous_reclaimed() const {
5830     return _humongous_regions_removed.length();
5831   }
5832 };
5833 
5834 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5835   assert_at_safepoint(true);
5836 
5837   if (!G1EagerReclaimHumongousObjects ||
5838       (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5839     g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5840     return;
5841   }
5842 
5843   double start_time = os::elapsedTime();
5844 
5845   FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5846 
5847   G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5848   heap_region_iterate(&cl);
5849 
5850   HeapRegionSetCount empty_set;
5851   remove_from_old_sets(empty_set, cl.humongous_free_count());
5852 
5853   G1HRPrinter* hrp = hr_printer();
5854   if (hrp->is_active()) {
5855     FreeRegionListIterator iter(&local_cleanup_list);
5856     while (iter.more_available()) {
5857       HeapRegion* hr = iter.get_next();
5858       hrp->cleanup(hr);
5859     }
5860   }
5861 
5862   prepend_to_freelist(&local_cleanup_list);
5863   decrement_summary_bytes(cl.bytes_freed());
5864 
5865   g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5866                                                                     cl.humongous_reclaimed());
5867 }
5868 
5869 // This routine is similar to the above but does not record
5870 // any policy statistics or update free lists; we are abandoning
5871 // the current incremental collection set in preparation of a
5872 // full collection. After the full GC we will start to build up
5873 // the incremental collection set again.
5874 // This is only called when we're doing a full collection
5875 // and is immediately followed by the tearing down of the young list.
5876 
5877 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5878   HeapRegion* cur = cs_head;
5879 
5880   while (cur != NULL) {
5881     HeapRegion* next = cur->next_in_collection_set();
5882     assert(cur->in_collection_set(), "bad CS");
5883     cur->set_next_in_collection_set(NULL);
5884     clear_in_cset(cur);
5885     cur->set_young_index_in_cset(-1);
5886     cur = next;
5887   }
5888 }
5889 
5890 void G1CollectedHeap::set_free_regions_coming() {
5891   if (G1ConcRegionFreeingVerbose) {
5892     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5893                            "setting free regions coming");
5894   }
5895 
5896   assert(!free_regions_coming(), "pre-condition");
5897   _free_regions_coming = true;
5898 }
5899 
5900 void G1CollectedHeap::reset_free_regions_coming() {
5901   assert(free_regions_coming(), "pre-condition");
5902 
5903   {
5904     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5905     _free_regions_coming = false;
5906     SecondaryFreeList_lock->notify_all();
5907   }
5908 
5909   if (G1ConcRegionFreeingVerbose) {
5910     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5911                            "reset free regions coming");
5912   }
5913 }
5914 
5915 void G1CollectedHeap::wait_while_free_regions_coming() {
5916   // Most of the time we won't have to wait, so let's do a quick test
5917   // first before we take the lock.
5918   if (!free_regions_coming()) {
5919     return;
5920   }
5921 
5922   if (G1ConcRegionFreeingVerbose) {
5923     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5924                            "waiting for free regions");
5925   }
5926 
5927   {
5928     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5929     while (free_regions_coming()) {
5930       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5931     }
5932   }
5933 
5934   if (G1ConcRegionFreeingVerbose) {
5935     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5936                            "done waiting for free regions");
5937   }
5938 }
5939 
5940 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5941   return _allocator->is_retained_old_region(hr);
5942 }
5943 
5944 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5945   _young_list->push_region(hr);
5946 }
5947 
5948 class NoYoungRegionsClosure: public HeapRegionClosure {
5949 private:
5950   bool _success;
5951 public:
5952   NoYoungRegionsClosure() : _success(true) { }
5953   bool doHeapRegion(HeapRegion* r) {
5954     if (r->is_young()) {
5955       gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5956                              p2i(r->bottom()), p2i(r->end()));
5957       _success = false;
5958     }
5959     return false;
5960   }
5961   bool success() { return _success; }
5962 };
5963 
5964 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5965   bool ret = _young_list->check_list_empty(check_sample);
5966 
5967   if (check_heap) {
5968     NoYoungRegionsClosure closure;
5969     heap_region_iterate(&closure);
5970     ret = ret && closure.success();
5971   }
5972 
5973   return ret;
5974 }
5975 
5976 class TearDownRegionSetsClosure : public HeapRegionClosure {
5977 private:
5978   HeapRegionSet *_old_set;
5979 
5980 public:
5981   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5982 
5983   bool doHeapRegion(HeapRegion* r) {
5984     if (r->is_old()) {
5985       _old_set->remove(r);
5986     } else {
5987       // We ignore free regions, we'll empty the free list afterwards.
5988       // We ignore young regions, we'll empty the young list afterwards.
5989       // We ignore humongous regions, we're not tearing down the
5990       // humongous regions set.
5991       assert(r->is_free() || r->is_young() || r->is_humongous(),
5992              "it cannot be another type");
5993     }
5994     return false;
5995   }
5996 
5997   ~TearDownRegionSetsClosure() {
5998     assert(_old_set->is_empty(), "post-condition");
5999   }
6000 };
6001 
6002 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6003   assert_at_safepoint(true /* should_be_vm_thread */);
6004 
6005   if (!free_list_only) {
6006     TearDownRegionSetsClosure cl(&_old_set);
6007     heap_region_iterate(&cl);
6008 
6009     // Note that emptying the _young_list is postponed and instead done as
6010     // the first step when rebuilding the regions sets again. The reason for
6011     // this is that during a full GC string deduplication needs to know if
6012     // a collected region was young or old when the full GC was initiated.
6013   }
6014   _hrm.remove_all_free_regions();
6015 }
6016 
6017 void G1CollectedHeap::increase_used(size_t bytes) {
6018   _summary_bytes_used += bytes;
6019 }
6020 
6021 void G1CollectedHeap::decrease_used(size_t bytes) {
6022   assert(_summary_bytes_used >= bytes,
6023          "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6024          _summary_bytes_used, bytes);
6025   _summary_bytes_used -= bytes;
6026 }
6027 
6028 void G1CollectedHeap::set_used(size_t bytes) {
6029   _summary_bytes_used = bytes;
6030 }
6031 
6032 class RebuildRegionSetsClosure : public HeapRegionClosure {
6033 private:
6034   bool            _free_list_only;
6035   HeapRegionSet*   _old_set;
6036   HeapRegionManager*   _hrm;
6037   size_t          _total_used;
6038 
6039 public:
6040   RebuildRegionSetsClosure(bool free_list_only,
6041                            HeapRegionSet* old_set, HeapRegionManager* hrm) :
6042     _free_list_only(free_list_only),
6043     _old_set(old_set), _hrm(hrm), _total_used(0) {
6044     assert(_hrm->num_free_regions() == 0, "pre-condition");
6045     if (!free_list_only) {
6046       assert(_old_set->is_empty(), "pre-condition");
6047     }
6048   }
6049 
6050   bool doHeapRegion(HeapRegion* r) {
6051     if (r->is_continues_humongous()) {
6052       return false;
6053     }
6054 
6055     if (r->is_empty()) {
6056       // Add free regions to the free list
6057       r->set_free();
6058       r->set_allocation_context(AllocationContext::system());
6059       _hrm->insert_into_free_list(r);
6060     } else if (!_free_list_only) {
6061       assert(!r->is_young(), "we should not come across young regions");
6062 
6063       if (r->is_humongous()) {
6064         // We ignore humongous regions. We left the humongous set unchanged.
6065       } else {
6066         // Objects that were compacted would have ended up on regions
6067         // that were previously old or free.  Archive regions (which are
6068         // old) will not have been touched.
6069         assert(r->is_free() || r->is_old(), "invariant");
6070         // We now consider them old, so register as such. Leave
6071         // archive regions set that way, however, while still adding
6072         // them to the old set.
6073         if (!r->is_archive()) {
6074           r->set_old();
6075         }
6076         _old_set->add(r);
6077       }
6078       _total_used += r->used();
6079     }
6080 
6081     return false;
6082   }
6083 
6084   size_t total_used() {
6085     return _total_used;
6086   }
6087 };
6088 
6089 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6090   assert_at_safepoint(true /* should_be_vm_thread */);
6091 
6092   if (!free_list_only) {
6093     _young_list->empty_list();
6094   }
6095 
6096   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6097   heap_region_iterate(&cl);
6098 
6099   if (!free_list_only) {
6100     set_used(cl.total_used());
6101     if (_archive_allocator != NULL) {
6102       _archive_allocator->clear_used();
6103     }
6104   }
6105   assert(used_unlocked() == recalculate_used(),
6106          "inconsistent used_unlocked(), "
6107          "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6108          used_unlocked(), recalculate_used());
6109 }
6110 
6111 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6112   _refine_cte_cl->set_concurrent(concurrent);
6113 }
6114 
6115 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6116   HeapRegion* hr = heap_region_containing(p);
6117   return hr->is_in(p);
6118 }
6119 
6120 // Methods for the mutator alloc region
6121 
6122 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6123                                                       bool force) {
6124   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6125   assert(!force || g1_policy()->can_expand_young_list(),
6126          "if force is true we should be able to expand the young list");
6127   bool young_list_full = g1_policy()->is_young_list_full();
6128   if (force || !young_list_full) {
6129     HeapRegion* new_alloc_region = new_region(word_size,
6130                                               false /* is_old */,
6131                                               false /* do_expand */);
6132     if (new_alloc_region != NULL) {
6133       set_region_short_lived_locked(new_alloc_region);
6134       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6135       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6136       return new_alloc_region;
6137     }
6138   }
6139   return NULL;
6140 }
6141 
6142 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6143                                                   size_t allocated_bytes) {
6144   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6145   assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6146 
6147   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6148   increase_used(allocated_bytes);
6149   _hr_printer.retire(alloc_region);
6150   // We update the eden sizes here, when the region is retired,
6151   // instead of when it's allocated, since this is the point that its
6152   // used space has been recored in _summary_bytes_used.
6153   g1mm()->update_eden_size();
6154 }
6155 
6156 // Methods for the GC alloc regions
6157 
6158 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6159                                                  uint count,
6160                                                  InCSetState dest) {
6161   assert(FreeList_lock->owned_by_self(), "pre-condition");
6162 
6163   if (count < g1_policy()->max_regions(dest)) {
6164     const bool is_survivor = (dest.is_young());
6165     HeapRegion* new_alloc_region = new_region(word_size,
6166                                               !is_survivor,
6167                                               true /* do_expand */);
6168     if (new_alloc_region != NULL) {
6169       // We really only need to do this for old regions given that we
6170       // should never scan survivors. But it doesn't hurt to do it
6171       // for survivors too.
6172       new_alloc_region->record_timestamp();
6173       if (is_survivor) {
6174         new_alloc_region->set_survivor();
6175         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6176         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6177       } else {
6178         new_alloc_region->set_old();
6179         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6180         check_bitmaps("Old Region Allocation", new_alloc_region);
6181       }
6182       bool during_im = collector_state()->during_initial_mark_pause();
6183       new_alloc_region->note_start_of_copying(during_im);
6184       return new_alloc_region;
6185     }
6186   }
6187   return NULL;
6188 }
6189 
6190 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6191                                              size_t allocated_bytes,
6192                                              InCSetState dest) {
6193   bool during_im = collector_state()->during_initial_mark_pause();
6194   alloc_region->note_end_of_copying(during_im);
6195   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6196   if (dest.is_young()) {
6197     young_list()->add_survivor_region(alloc_region);
6198   } else {
6199     _old_set.add(alloc_region);
6200   }
6201   _hr_printer.retire(alloc_region);
6202 }
6203 
6204 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6205   bool expanded = false;
6206   uint index = _hrm.find_highest_free(&expanded);
6207 
6208   if (index != G1_NO_HRM_INDEX) {
6209     if (expanded) {
6210       ergo_verbose1(ErgoHeapSizing,
6211                     "attempt heap expansion",
6212                     ergo_format_reason("requested address range outside heap bounds")
6213                     ergo_format_byte("region size"),
6214                     HeapRegion::GrainWords * HeapWordSize);
6215     }
6216     _hrm.allocate_free_regions_starting_at(index, 1);
6217     return region_at(index);
6218   }
6219   return NULL;
6220 }
6221 
6222 // Heap region set verification
6223 
6224 class VerifyRegionListsClosure : public HeapRegionClosure {
6225 private:
6226   HeapRegionSet*   _old_set;
6227   HeapRegionSet*   _humongous_set;
6228   HeapRegionManager*   _hrm;
6229 
6230 public:
6231   HeapRegionSetCount _old_count;
6232   HeapRegionSetCount _humongous_count;
6233   HeapRegionSetCount _free_count;
6234 
6235   VerifyRegionListsClosure(HeapRegionSet* old_set,
6236                            HeapRegionSet* humongous_set,
6237                            HeapRegionManager* hrm) :
6238     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6239     _old_count(), _humongous_count(), _free_count(){ }
6240 
6241   bool doHeapRegion(HeapRegion* hr) {
6242     if (hr->is_continues_humongous()) {
6243       return false;
6244     }
6245 
6246     if (hr->is_young()) {
6247       // TODO
6248     } else if (hr->is_starts_humongous()) {
6249       assert(hr->containing_set() == _humongous_set, "Heap region %u is starts humongous but not in humongous set.", hr->hrm_index());
6250       _humongous_count.increment(1u, hr->capacity());
6251     } else if (hr->is_empty()) {
6252       assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6253       _free_count.increment(1u, hr->capacity());
6254     } else if (hr->is_old()) {
6255       assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6256       _old_count.increment(1u, hr->capacity());
6257     } else {
6258       // There are no other valid region types. Check for one invalid
6259       // one we can identify: pinned without old or humongous set.
6260       assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6261       ShouldNotReachHere();
6262     }
6263     return false;
6264   }
6265 
6266   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6267     guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6268     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6269               old_set->total_capacity_bytes(), _old_count.capacity());
6270 
6271     guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6272     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6273               humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6274 
6275     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());
6276     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6277               free_list->total_capacity_bytes(), _free_count.capacity());
6278   }
6279 };
6280 
6281 void G1CollectedHeap::verify_region_sets() {
6282   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6283 
6284   // First, check the explicit lists.
6285   _hrm.verify();
6286   {
6287     // Given that a concurrent operation might be adding regions to
6288     // the secondary free list we have to take the lock before
6289     // verifying it.
6290     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6291     _secondary_free_list.verify_list();
6292   }
6293 
6294   // If a concurrent region freeing operation is in progress it will
6295   // be difficult to correctly attributed any free regions we come
6296   // across to the correct free list given that they might belong to
6297   // one of several (free_list, secondary_free_list, any local lists,
6298   // etc.). So, if that's the case we will skip the rest of the
6299   // verification operation. Alternatively, waiting for the concurrent
6300   // operation to complete will have a non-trivial effect on the GC's
6301   // operation (no concurrent operation will last longer than the
6302   // interval between two calls to verification) and it might hide
6303   // any issues that we would like to catch during testing.
6304   if (free_regions_coming()) {
6305     return;
6306   }
6307 
6308   // Make sure we append the secondary_free_list on the free_list so
6309   // that all free regions we will come across can be safely
6310   // attributed to the free_list.
6311   append_secondary_free_list_if_not_empty_with_lock();
6312 
6313   // Finally, make sure that the region accounting in the lists is
6314   // consistent with what we see in the heap.
6315 
6316   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6317   heap_region_iterate(&cl);
6318   cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6319 }
6320 
6321 // Optimized nmethod scanning
6322 
6323 class RegisterNMethodOopClosure: public OopClosure {
6324   G1CollectedHeap* _g1h;
6325   nmethod* _nm;
6326 
6327   template <class T> void do_oop_work(T* p) {
6328     T heap_oop = oopDesc::load_heap_oop(p);
6329     if (!oopDesc::is_null(heap_oop)) {
6330       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6331       HeapRegion* hr = _g1h->heap_region_containing(obj);
6332       assert(!hr->is_continues_humongous(),
6333              "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6334              " starting at " HR_FORMAT,
6335              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6336 
6337       // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6338       hr->add_strong_code_root_locked(_nm);
6339     }
6340   }
6341 
6342 public:
6343   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6344     _g1h(g1h), _nm(nm) {}
6345 
6346   void do_oop(oop* p)       { do_oop_work(p); }
6347   void do_oop(narrowOop* p) { do_oop_work(p); }
6348 };
6349 
6350 class UnregisterNMethodOopClosure: public OopClosure {
6351   G1CollectedHeap* _g1h;
6352   nmethod* _nm;
6353 
6354   template <class T> void do_oop_work(T* p) {
6355     T heap_oop = oopDesc::load_heap_oop(p);
6356     if (!oopDesc::is_null(heap_oop)) {
6357       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6358       HeapRegion* hr = _g1h->heap_region_containing(obj);
6359       assert(!hr->is_continues_humongous(),
6360              "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6361              " starting at " HR_FORMAT,
6362              p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6363 
6364       hr->remove_strong_code_root(_nm);
6365     }
6366   }
6367 
6368 public:
6369   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6370     _g1h(g1h), _nm(nm) {}
6371 
6372   void do_oop(oop* p)       { do_oop_work(p); }
6373   void do_oop(narrowOop* p) { do_oop_work(p); }
6374 };
6375 
6376 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6377   CollectedHeap::register_nmethod(nm);
6378 
6379   guarantee(nm != NULL, "sanity");
6380   RegisterNMethodOopClosure reg_cl(this, nm);
6381   nm->oops_do(&reg_cl);
6382 }
6383 
6384 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6385   CollectedHeap::unregister_nmethod(nm);
6386 
6387   guarantee(nm != NULL, "sanity");
6388   UnregisterNMethodOopClosure reg_cl(this, nm);
6389   nm->oops_do(&reg_cl, true);
6390 }
6391 
6392 void G1CollectedHeap::purge_code_root_memory() {
6393   double purge_start = os::elapsedTime();
6394   G1CodeRootSet::purge();
6395   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6396   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6397 }
6398 
6399 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6400   G1CollectedHeap* _g1h;
6401 
6402 public:
6403   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6404     _g1h(g1h) {}
6405 
6406   void do_code_blob(CodeBlob* cb) {
6407     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6408     if (nm == NULL) {
6409       return;
6410     }
6411 
6412     if (ScavengeRootsInCode) {
6413       _g1h->register_nmethod(nm);
6414     }
6415   }
6416 };
6417 
6418 void G1CollectedHeap::rebuild_strong_code_roots() {
6419   RebuildStrongCodeRootClosure blob_cl(this);
6420   CodeCache::blobs_do(&blob_cl);
6421 }
--- EOF ---